JP2006001174A - Droplet ejection apparatus, ejection abnormality detection method and program for droplet ejection head - Google Patents

Abstract

PROBLEM TO BE SOLVED To accurately identify a cause of abnormal discharge of a droplet of a nozzle.
In the present invention, when an actuator 22 is driven and a droplet discharge operation is performed, residual vibration of a diaphragm displaced by the actuator is detected, and based on a residual vibration pattern of the diaphragm. Detecting whether or not the droplets were ejected normally, and in the case of abnormal ejection, the cause of abnormal ejection of the droplets is based on the pulse width measurement value measured from the residual vibration waveform of the residual vibration of the diaphragm When it is determined whether or not it is due to mixing, and it is determined that the cause of the droplet ejection abnormality is other than bubble mixing, the initial pulse width measurement value measured from the residual vibration waveform of the residual vibration of the diaphragm in the initial state The measured value is compared with the sequential measurement value of the pulse width measurement value every time the droplet discharge operation is driven a predetermined number of times after the initial state, and the initial measurement value is sequentially measured according to the increase in the number of times of droplet discharge operation driving. Large value Determines that paper dust abnormal if and to determine the drying abnormal if smaller reversed.
[Selection] Figure 10

Description

  The present invention relates to a droplet discharge apparatus such as an ink jet printer, a discharge abnormality detection method for the droplet discharge head, and a program.

  An ink jet printer, which is one of the droplet discharge devices, forms an image on a predetermined sheet by discharging ink droplets (droplets) from a plurality of nozzles. An ink jet head (print head) of an ink jet printer is provided with a number of nozzles. However, some nozzles may become visible due to an increase in ink viscosity, air bubbles, dust or paper dust. There are cases where clogged and ink droplets cannot be ejected. When the nozzles are clogged, missing dots occur in the image, which causes the image quality to deteriorate.

Conventionally, in order to solve such problems, as a device for inspecting whether or not ink droplets are ejected, an ink droplet passes between the light emitting element and the light receiving element that are provided with an ink ejecting nozzle interposed therebetween. It is known to detect changes in the intensity of light due to light and check the operation of each nozzle (see, for example, Patent Document 1).
In this optical detection method, a space for installing an optical sensor is required, and in order to detect minute ink droplets with high sensitivity, the accuracy of the detection position and detection timing at which the ink droplets pass through the light receiving region is increased. There is an unresolved issue that must be solved.

In order to solve this unsolved problem, as a device for inspecting the presence or absence of ejection of ink droplets, a diaphragm, an electrostatic actuator for displacing the diaphragm, and a liquid are filled therein. A droplet discharge head having a cavity in which the internal pressure is increased and decreased, a nozzle that communicates with the cavity and discharges liquid as droplets by increasing and decreasing the pressure in the cavity, and a drive circuit that drives the electrostatic actuator; , A residual vibration detecting means for detecting the residual vibration of the diaphragm, and a technique for detecting the abnormal discharge of the droplets based on the residual vibration of the diaphragm detected by the residual vibration detecting means and confirming the operation of each nozzle There is.
JP 2002-192740 A

  However, in the technique described above, although abnormality of the nozzle can be detected, changes in the residual vibration waveform appear in the same tendency with respect to nozzle drying and paper dust adhesion, so it is difficult to distinguish between them. The problem remained. In these recovery processes, the ink thickened by pump suction is sucked in the case of drying, and the wiping process is performed in the case of paper dust adhesion. For this reason, since it is impossible to determine whether the cause of abnormal discharge of nozzle droplets is due to nozzle drying or paper dust adhesion, both the pump suction and wiping processes were executed, and the recovery process took time. In addition, since the pump suction is performed even if paper dust adheres, ink drops are wasted.

  Therefore, the present invention has been made paying attention to such an unsolved problem, and is a droplet discharge device and a droplet discharge head that can accurately identify the cause of abnormal discharge of a droplet from a nozzle. It is an object of the present invention to provide a discharge abnormality detection method and program.

In order to solve the above problems and achieve the object of the present invention, each invention is configured as follows. That is, the first invention is
A diaphragm, an actuator for displacing the diaphragm, a cavity filled with liquid droplets, and an internal pressure increased or decreased by the displacement of the diaphragm, and a liquid communicating with the cavity by increasing or decreasing the pressure inside the cavity A droplet discharge head having a nozzle for discharging the droplet as a droplet;
Drive means for outputting a predetermined drive signal for driving the actuator;
Residual vibration detecting means for detecting residual vibration of the diaphragm;
An abnormal discharge detecting means for detecting an abnormal discharge of a droplet based on the residual vibration pattern of the diaphragm detected by the residual vibration detecting means;
The residual vibration pattern detected by the residual vibration detection means after the drive signal is output a predetermined number of times so that the acoustic impedance around the nozzle is changed by the drive means when the discharge abnormality detection means detects the discharge abnormality. And a sorting means for sorting out the cause of abnormal discharge of the nozzles.

According to the present invention having such a configuration, it is possible to accurately identify the cause of abnormal discharge of nozzle droplets.
The second invention is
A diaphragm, an actuator for displacing the diaphragm, a cavity filled with liquid droplets, and an internal pressure increased or decreased by the displacement of the diaphragm, and a liquid communicating with the cavity by increasing or decreasing the pressure inside the cavity A droplet discharge head having a nozzle for discharging the droplet as a droplet;
Drive means for outputting a predetermined drive signal for driving the actuator;
Residual vibration detecting means for detecting residual vibration of the diaphragm;
An abnormal discharge detecting means for detecting an abnormal discharge of a droplet based on the residual vibration pattern of the diaphragm detected by the residual vibration detecting means;
The residual vibration pattern detected by the residual vibration detection means after the drive signal is output a predetermined number of times so that the acoustic impedance around the nozzle is changed by the drive means when the discharge abnormality detection means detects the discharge abnormality. Sorting means for sorting the cause of abnormal discharge of the nozzle based on
The discharge abnormality detecting means, and a recovery processing means for performing a recovery process according to the sorting result of the sorting means.

According to the present invention having such a configuration, it is possible to accurately specify the cause of abnormal discharge of nozzle droplets, and it is possible to perform optimal recovery processing according to the cause.
According to a third invention, in the first or second invention,
The ejection abnormality detection means indicates a pulse width measurement unit that measures the pulse width of the residual vibration waveform of the diaphragm, a measurement value of the pulse width measurement unit, and a normal range of the pulse width in the residual vibration waveform of the diaphragm Comparison means for comparing with a normal discharge reference value, first determination means for determining whether or not a droplet discharged from a nozzle is normal based on a comparison result of the comparison means, and the first determination A second determination unit that determines whether or not the cause of the droplet discharge abnormality from the nozzle is a mixture of bubbles when the droplet discharged from the nozzle is abnormal, When the determination result of the determination means is not mixed with bubbles, a classification signal indicating this and the measurement value of the pulse width measurement unit are output to the classification means.

According to the present invention having such a configuration, when an abnormal discharge of a nozzle droplet occurs, it is determined based on the pulse width of the residual vibration waveform whether the cause of the abnormality is due to bubble mixing. When the bubbles are not mixed, the cause analysis by the sorting means can be performed, and the cause of the ejection abnormality can be specified accurately.
According to a fourth invention, in the third invention,
The second determination unit determines that there is a bubble mixing abnormality when the measurement value of the pulse width measurement unit is less than a normal discharge reference value indicating a lower limit value of a normal range, and the measurement value of the pulse width measurement unit When the value exceeds the normal discharge reference value indicating the upper limit value of the normal range, it is determined that there is an abnormality other than air bubble mixing.

According to the present invention having such a configuration, it is possible to accurately determine that the cause of the abnormal discharge of the nozzle droplet is an abnormality due to bubble mixing when the pulse width of the residual vibration waveform is less than the normal range. Can do.
According to a fifth invention, in the third or fourth invention,
The classification unit includes a first storage unit that stores an initial measurement value of the pulse width measurement unit in an initial state based on a classification signal input from the ejection abnormality detection unit, and the drive unit after the initial state. A storage unit including a second storage unit that sequentially stores measurement values of the pulse width measurement unit every time it is driven a predetermined number of times, and an initial measurement value stored in the first storage unit of the storage unit, Sequential comparison means for comparing the sequential measurement values stored in the second storage unit, and the comparison result of the comparison means indicates that the initial measurement value is less than the sequential measurement value in accordance with an increase in the number of times of driving of the drive means. And an abnormality determining means for determining that the paper dust is abnormal.

According to the present invention having such a configuration, the initial measurement value of the pulse width of the residual vibration waveform is compared with the sequential measurement value measured thereafter, and the initial measurement value is determined by the change in the acoustic impedance due to the liquid seepage. When it becomes less than the measured value sequentially, it can be identified that the cause of the abnormal discharge of the nozzle droplets is the abnormal paper dust.
A sixth invention is the third or fourth invention, wherein
The classification unit includes a first storage unit that stores an initial measurement value of the pulse width measurement unit in an initial state based on a classification signal input from the ejection abnormality detection unit, and the drive unit after the initial state. A storage unit including a second storage unit that sequentially stores measurement values of the pulse width measurement unit every time it is driven a predetermined number of times, and an initial measurement value stored in the first storage unit of the storage unit, Sequential comparison means for comparing the sequential measurement values stored in the second storage unit, and the comparison result of the comparison means indicates that the initial measurement value becomes the sequential measurement value in accordance with an increase in the number of driving times of the drive means. And an abnormality determining means for determining that it is dry abnormality when exceeding.

According to the present invention having such a configuration, the initial measurement value of the pulse width of the residual vibration waveform is compared with the sequentially measured value measured thereafter, and the change in the acoustic impedance due to the increase in the viscosity of the ink near the nozzle Thus, when the initial measurement value sequentially exceeds the measurement value, it is possible to specify that the cause of the abnormal discharge of the nozzle droplets is the dry abnormality.
A seventh invention is the third or fourth invention, wherein
The classification unit includes a first storage unit that stores an initial measurement value of the pulse width measurement unit in an initial state based on a classification signal input from the ejection abnormality detection unit, and the drive unit after the initial state. A storage unit including a second storage unit that sequentially stores measurement values of the pulse width measurement unit every time it is driven a predetermined number of times, and an initial measurement value stored in the first storage unit of the storage unit, Sequential comparison means for comparing the sequential measurement values stored in the second storage unit, and the comparison result of the comparison means indicates that the initial measurement value is less than the sequential measurement value in accordance with an increase in the number of times of driving of the drive means. It is determined that there is a paper dust abnormality when the value becomes, and when the comparison result of the comparison means exceeds the sequential measurement value in response to an increase in the number of times the drive means is driven, a dry abnormality is detected. An abnormality judging means for judging That.

  According to the present invention having such a configuration, the initial measurement value of the pulse width of the residual vibration waveform is compared with the sequential measurement value measured thereafter, and the initial measurement value is determined by the change in the acoustic impedance due to the liquid seepage. When the measured value is successively less than the measured value, it is possible to identify that the cause of abnormal discharge of paper droplets from the nozzle is paper powder abnormality, and the initial state is due to the change in acoustic impedance due to the increased viscosity of the ink near the nozzle. When the measured value sequentially exceeds the measured value, it is possible to specify that the cause of the abnormal discharge of the nozzle droplets is the dry abnormality.

An eighth invention is the first or second invention, wherein
The number of times of output of the drive signal by the drive means is set to the number of times that the sorting means can specify whether the cause of abnormal discharge of droplets from the nozzle is due to abnormal drying or abnormal paper dust. Yes.
According to the present invention having such a configuration, the number of times required to detect the cause of the abnormal discharge of the droplets from the nozzles can be determined in advance by experiments or the like, so the initial measurement of the pulse width of the residual vibration waveform By comparing the measured value and the sequentially measured value measured thereafter, it is possible to specify whether it is due to abnormal drying or due to abnormal paper dust.

A ninth invention is the fifth to eighth invention,
The classification unit includes a drive stop unit that stops driving the drive unit and the residual vibration detection unit when an abnormality determination is made by the abnormality determination unit.
According to the present invention having such a configuration, when the abnormality can be determined, the driving of the driving unit and the residual vibration detecting unit can be stopped quickly, so that the detection of abnormal discharge of the nozzle droplets can be performed. For this reason, it is possible to eliminate a useless droplet discharge operation.

A tenth invention is the fifth to eighth invention,
The separation means is a drive stop means for stopping the drive of the drive means and the residual vibration detection means when an abnormality determination result by the abnormality determination means is not obtained before the number of times of driving reaches a predetermined number of times. It has.
According to the present invention having such a configuration, when the abnormality determination cannot be made, the driving of the driving unit and the residual vibration detecting unit can be stopped quickly. It is possible to eliminate a useless droplet discharge operation for detection.

The eleventh invention is
The actuator including the diaphragm is driven by a drive signal to vibrate the diaphragm, and after the operation of discharging the liquid in the cavity as a droplet from the nozzle, the residual vibration of the diaphragm is detected and detected. A normal determination step for determining whether or not a droplet ejected from a nozzle is normal from the initial pattern of the residual vibration waveform, and when it is determined abnormal in the normal determination step, the cause of abnormal discharge is a bubble A bubble determination step for determining whether or not it is mixed, and when the determination result of the bubble determination step is not bubble mixing, the operation of discharging the liquid from the nozzle is performed a predetermined number of times, and then the initial residual vibration of the diaphragm and thereafter A separation step is provided to detect whether the droplet discharge abnormality from the nozzle is a drying abnormality or a paper dust abnormality by detecting the residual vibration pattern of the nozzle and comparing the two. To have.

Thereby, the same effect as the droplet discharge device of the first invention can be obtained.
The twelfth invention
The actuator including the diaphragm is driven by a drive signal to vibrate the diaphragm, and after the operation of discharging the liquid in the cavity as a droplet from the nozzle, the residual vibration of the diaphragm is detected and detected. A normal determination step for determining whether or not a droplet ejected from a nozzle is normal from the initial pattern of the residual vibration waveform, and when it is determined abnormal in the normal determination step, the cause of abnormal discharge is a bubble A bubble determination step for determining whether or not it is mixed, and when the determination result of the bubble determination step is not bubble mixing, the operation of discharging the liquid from the nozzle is performed a predetermined number of times, and then the initial residual vibration of the diaphragm and thereafter Detecting a residual vibration pattern of the nozzle and comparing the two to determine whether a droplet discharge abnormality from the nozzle is a drying abnormality or a paper dust abnormality; Is a program to be executed by a computer.

  With such a configuration, when the program is read by the computer and the computer executes processing according to the read program, the same operation and effect as those of the droplet discharge device of the first invention can be obtained.

Hereinafter, embodiments of a droplet discharge device and a discharge abnormality detection method for a droplet discharge head according to the present invention will be described with reference to the drawings.
FIG. 1 is a plan view showing a schematic configuration of an ink jet printer 1 which is a kind of droplet discharge device according to an embodiment of the present invention.
As shown in FIG. 1, the ink jet printer 1 includes a carriage 4 on which a head unit 2 and an ink cartridge 3 are mounted. The carriage 4 is guided by a set of carriage shafts 5 and can move in the main scanning direction. It has become. A part of the carriage 4 is fixed to a toothed belt 9, and the toothed belt 9 is stretched between a driving pulley 7 and a driven pulley 8 fixed to a rotating shaft of the motor 6.

Furthermore, an encoder 10 is attached to the carriage 4, and a linear scale 11 is provided along the moving direction of the carriage 4. Thereby, the position of the head unit 2 on the carriage 4 is detected by the encoder 10.
In FIG. 1, reference numeral 12 denotes a cable for electrical connection between the head unit 2 and the system controller. Reference numeral 13 denotes a wiper for cleaning the surface of an ink jet head described later. Reference numeral 14 denotes a cap for capping the nozzle substrate (see FIG. 3) of the inkjet head.

In the inkjet printer 1 having such a configuration, when the detection signal of the encoder 10 is input to a motor control circuit (not shown), the rotation operation of the motor 6 is controlled by the motor control circuit as follows. That is, acceleration, constant speed, deceleration, inversion, acceleration, constant speed, deceleration, inversion, and so on are controlled.
Along with the operation of the motor 6, the carriage 4 repeats reciprocating movement in the main scanning direction, and the constant speed section corresponds to the printing area. Therefore, the head unit 2 mounted on the carriage 4 at the constant speed. Ink droplets are ejected from the nozzles onto the recording paper a. As a result, predetermined characters and images are recorded on the recording paper a by the ink droplets.

Next, a specific configuration of the head unit 2 shown in FIG. 1 will be described with reference to FIGS.
As shown in FIG. 2, the head unit 2 includes a large number of ink jet heads (droplet discharge heads) 20, and each ink jet head 20 uses an electrostatic actuator.

  As shown in FIG. 2, the inkjet head 20 includes a vibration plate 21, an electrostatic actuator 22 that includes the vibration plate 21 and displaces the vibration plate 21, and a displacement of the vibration plate 21 that is filled with liquid ink. At least a cavity (pressure chamber) 23 in which the internal pressure is increased and decreased, and a nozzle 24 that communicates with the cavity 23 and discharges ink as droplets by increasing and decreasing the pressure in the cavity 23.

  More specifically, the head unit 2 has a three-layer structure in which a silicon nozzle substrate 26 is stacked on the upper side and a glass substrate 27 is stacked on the lower side with a central silicon substrate 25 interposed therebetween. A cavity 23 and a reservoir 28 communicating therewith are defined between the central silicon substrate 25 and the upper nozzle substrate 26. The reservoir 28 communicates with an ink intake port 29 provided on the glass substrate 27.

Further, a gap 31 is formed between the diaphragm 21 formed by the central silicon substrate 25 and functioning as the bottom plate of the cavity 23 and the individual electrode 30 provided on the glass substrate 27. The diaphragm 21 is connected to the common electrode 32.
Accordingly, the main part of the electrostatic actuator 22 is formed by the diaphragm 21, the individual electrode 30, and the gap 31 formed therebetween, and is applied between the individual electrode 30 and the common electrode 32. It is driven by a drive signal.

The nozzles 24 for each inkjet head 20 formed on the nozzle substrate 26 shown in FIG. 2 are arranged, for example, as shown in FIG. In the example of FIG. 3, an arrangement pattern of the nozzles 24 when applied to four colors of ink (Y, M, C, K) is shown.
In the ink jet printer 1 having such an ink jet head 20, ink is discharged from the nozzle 24 due to causes such as out of ink, generation of air bubbles (abnormality of air bubbles), clogging (abnormality of drying), adhesion of paper dust (abnormality of paper dust) and the like. Ink droplet ejection abnormalities (non-ejection), that is, ejection of droplets when they should be ejected, a so-called dot dropout phenomenon may occur.

Here, the paper dust is easily generated when a recording paper made of wood pulp as a raw material is brought into frictional contact with a paper feed roller or the like, and means a part of the recording paper that is fibrous or an aggregate thereof.
Next, the principle of detection of ink droplet ejection abnormality according to the present invention will be described with reference to FIGS. 2, 4, and 5.
When a driving signal is supplied to the electrostatic actuator 22 shown in FIG. 2 from a driving circuit, which will be described later, the diaphragm 21 is attracted to the individual electrode 30 side by electrostatic attraction force, elastic energy is accumulated, and driving signal is supplied. When is stopped, elastic energy is released. At this time, the diaphragm 21 is returned to the side opposite to the individual electrode 30 side, and the pressure in the cavity 23 increases and further decreases. As a result, a part of the ink filling the cavity 23 is ejected as an ink droplet from the nozzle 24 communicating with the cavity 23.

By a series of operations of the vibration plate 21, it is determined by the acoustic resistance r due to the viscosity of the nozzle 24, the ink intake port 29, or the ink, the inertance m due to the ink weight in the ink flow path, and the compliance c of the vibration plate 21. The diaphragm 21 generates free vibration at the natural vibration frequency. Hereinafter, the free vibration caused by the diaphragm 21 is referred to as residual vibration.
FIG. 4 shows a calculation model of simple vibration assuming residual vibration of the diaphragm 21. When the step response when the sound pressure P is applied to this calculation model is calculated for the volume velocity u, the following equation can be obtained.

Here, if the ink jet head 20 shown in FIG. 2 normally ejects ink and the acoustic resistance r, inertance m, and compliance c do not change, the residual vibration of the diaphragm 21 always has a constant waveform.
However, when ink ejection is defective and dot missing occurs, the residual vibration waveform of the vibration plate 21 is different from that in the normal state. FIG. 5 shows an example of the experimental result of the residual vibration detection waveform. From the results of this experiment and the calculation model of simple vibrations, we found the following.

(1) In the case of an abnormal air bubble mixture where air bubbles are clogged in the ink flow path or the tip of the nozzle, the ink weight is reduced by the amount of air bubbles mixed in, the inertance m is reduced, and the nozzle diameter is increased by the air bubbles. It can be detected as a characteristic residual vibration waveform that is equivalent to the state and the acoustic resistance r decreases and the frequency increases (see “Bubble mixing” in FIG. 5).
(2) In the case of a drying abnormality in which the ink in the nozzle portion is dried and no longer ejects, the viscosity of the ink near the nozzle increases due to the drying, the acoustic resistance r increases, and overdamping occurs (the frequency is low). It can be detected as a characteristic residual vibration waveform (see “Drying” in FIG. 5).

  (3) In the case of an abnormal paper dust in which paper dust or dust adheres to the nozzle surface, the ink oozes out from the nozzle by the paper dust, so that the ink weight viewed from the diaphragm increases and the inertance m increases. Further, the acoustic resistance r is increased by the paper dust fibers adhering to the nozzle, and it can be detected as a characteristic residual vibration waveform in which the period becomes larger (frequency becomes lower) than the period of normal ejection (see FIG. 5 “Paper dust”).

The present invention detects the ink droplet ejection abnormality (nozzle ejection abnormality) of the inkjet head 20 by detecting such residual vibration of the vibration plate 21, and the principle of detection of the residual vibration is described. Will be described with reference to FIG.
As shown in FIG. 6, when the electrostatic actuator 22 shown in FIG. 2 is considered as a capacitor in which the individual electrode 30 and the diaphragm 21 are parallel plates, the gap (gap) of the capacitor is caused by the residual vibration of the diaphragm 21. ) Changes, and the capacitance C (x) of the capacitor changes as shown in equation (4).

  On the other hand, the charge Q remains in the capacitor immediately after the electrostatic actuator 22 is disconnected from the drive circuit described later, that is, immediately after the supply of the drive signal is stopped. Therefore, the charging voltage Vc of the capacitor changes according to the change of the capacitance C of the capacitor as shown in the equation (5), and the mechanical residual vibration of the diaphragm 21 can be detected as the voltage change. it can.

Here, S is the area of each of the diaphragm 21 and the individual electrode 30, g is the distance between them (initial gap), ε is the dielectric constant of the air gap 31, and x is the diaphragm generated by the residual vibration of the diaphragm 21. 21 is a displacement amount from the reference position.
From the above, it is possible to detect the non-ejection of ink droplets by the change in the residual vibration of the vibration plate 21 and to identify the cause of clogging. In the case of (2) dry abnormality and (3) paper dust abnormality Since the change of the residual vibration waveform tends to attenuate the waveform, it is difficult to distinguish them.

In the present invention, a dry abnormality and a paper dust abnormality are separated as follows.
In the case of nozzle drying, which is recovered by preliminary ejection that preliminarily ejects droplets from the nozzle by driving the actuator, the ink that has been thickened around the nozzle by the ejection operation is gradually mixed with the new ink so that it is gradually appropriate. Ink viscosity becomes high, the acoustic resistance r changes to a normal value, and the nozzle tends to recover. On the other hand, in the case of paper dust adhesion, the acoustic resistance r and the inertance m increase as the ink oozes out of the paper dust adhered to the nozzle. In this case, the acoustic resistance r and the inertance m tend to further increase due to the preliminary ejection. Therefore, paper powder and drying can be separated by performing the discharge operation a plurality of times, changing the acoustic impedance around the nozzle, and knowing the tendency of the residual vibration to change.

As for nozzle drying and paper dust adhesion, after performing preliminary discharge by changing the number of droplet discharge (hereinafter referred to as Shot number), the experimental result of detecting the residual vibration waveform and the calculated waveform are consistent with each other as before. The tendency was observed by adjusting the acoustic resistance r and inertance m in the calculation model.
FIG. 7 shows a change in the residual vibration waveform depending on the Shot number in the case of abnormal drying. As shown in FIG. 7A, the residual vibration waveform after the 4shot discharge is a greatly attenuated waveform. At this time, the acoustic resistance r was about twice that during normal ejection. Further, in the residual vibration waveform after 10 Shot discharge, FIG. 7B, the attenuation of the waveform is reduced (the frequency is increased), and the acoustic resistance r is about 1.4 times that during normal discharge. Subsequently, in the residual vibration waveform after 32 Shot discharge, FIG. 7C, the waveform attenuation was further reduced, and the acoustic resistance r was about 1.25 times that during normal discharge. A state close to a normal residual vibration waveform was obtained by preliminary discharge of 32 shots or more.

Therefore, in the case of nozzle drying, the residual vibration waveform tends to approach the normal waveform (the frequency becomes higher) with an increase in the number of shots for preliminary ejection, and can be classified.
FIG. 8 shows a photograph of the shot number and the appearance of paper dust adhesion, and a schematic cross-sectional view. FIG. 9 shows changes in the residual vibration waveform depending on the number of shots when paper dust is abnormal.
FIG. 8A is a photograph of a nozzle before paper dust adheres, and a schematic cross-sectional view. The nozzle used in the experiment is indicated by a white circle in the left-hand photo of FIG. 8A and indicated by an arrow.

  FIG. 8B is a photograph and a cross-sectional schematic diagram of the nozzle after 2 Shot discharge in a state where paper dust adheres to the nozzle of FIG. As can be seen in the photograph on the left side of FIG. 8B and the schematic cross-sectional view on the right side, the ink spreads from the nozzles through the paper dust and forms an ink reservoir. In this case, since the amount of ink oozing out in contact with the nozzle is small, the change in acoustic impedance is small.

FIG. 8C is a photograph and a cross-sectional schematic diagram of the nozzle after 10 Shot discharge. As shown in the left photograph and the schematic cross-sectional view on the right side of FIG. 8 (c), although the amount of ink spilled from the nozzle along the paper powder increases in the lateral direction, the ink pool increases, The amount of ink oozing out is still small.
FIG. 9A shows a waveform based on a calculated value of residual vibration after 10 Shot discharge, a waveform of a measurement result, and a waveform of a measurement result in the case of normal discharge. As shown in FIG. 9A, the waveform of the measurement result of the residual vibration after 10 Shot discharge is slightly delayed from the normal residual vibration waveform. At this time, the acoustic resistance r was about 1.3 times that during normal ejection, and the inertance m was about 1.2 times.

FIG. 9B shows a waveform based on the calculated value of the residual vibration after the 32shot discharge and a waveform of the measurement result. As can be seen in FIG. 9B, the attenuation of the waveform is increased, the acoustic resistance r is about 1.7 times that during normal ejection, and the inertance m is about 1.7 times.
FIG. 8D is a photograph and a cross-sectional schematic diagram of the nozzle after 256 Shot discharge. As can be seen in the photograph on the left side of FIG. 8D and the schematic cross-sectional view on the right side, the paper dust adhering to the nozzle and the horizontal ink reservoir are combined to form a large ink reservoir around the nozzle.

FIG. 9C shows a waveform based on a calculated value of residual vibration after 256 Shot discharge and a waveform of a measurement result. As shown in FIG. 9C, the waveform attenuation is further increased (frequency is lowered), the acoustic resistance r is about 2.0 times that of normal ejection, and the inertance m is about 2.0 times. .
Therefore, in the case of paper dust adhesion, it can be distinguished by showing a change opposite to that of drying, and showing a tendency that the attenuation of the residual vibration waveform increases (frequency decreases) as the number of shots of preliminary ejection increases.

Next, based on the detection principle and the classification principle of the residual vibration, when it is necessary to detect the ink droplet ejection abnormality (nozzle missing from the nozzle) of the inkjet head 20, the residual vibration is detected and the cause is classified. Embodiments of the present invention that are performed will be described with reference to FIGS. 2, 10 to 16, and 18.
In this embodiment, as shown in FIG. 10, a control unit 102 that controls the entire system, a drive circuit 104 as a drive unit that drives the actuator 22 by a drive instruction signal output from the control unit 102, and an actuator 22 Residual vibration detection unit 106 as residual vibration detection means for detecting residual vibration of the ink, and discharge abnormality detection circuit as discharge abnormality detection means for detecting discharge abnormality based on the pulse width measurement value output from residual vibration detection unit 106 110 and a sorting circuit 112 as a sorting unit that sorts a drying abnormality and a paper dust abnormality based on a pulse width measurement value when an ejection abnormality is detected by the ejection abnormality detection circuit 110.

  The electrostatic actuator which is one embodiment of the actuator 22 is provided for each inkjet head 20 as shown in FIG. 2, and as described above, the main part is the diaphragm 21, the individual electrode 30, and the space between them. 6 and is equivalently expressed by a capacitor as shown in FIG. The diaphragm 21 is connected to a terminal of a changeover switch 116 described later.

The drive circuit 104 is a circuit that outputs a drive signal (drive voltage) for driving the actuator 22 based on a drive instruction signal output from the control unit 102 that is a system controller, and outputs a normal drive signal when an image is formed with ink droplets. When a discharge abnormality of ink droplets is detected, a drive signal (see FIG. 18A) described later is output.
Further, the drive circuit 104 outputs a pause signal (see FIG. 18B) to the detection timing generation circuit 114 described later for a predetermined time from the timing when the drive signal is turned off.

  The residual vibration detection unit 106 detects the residual vibration of the actuator 22 based on the drive signal output from the drive circuit 104 and the detection timing setting value output from the control unit 102, and the residual vibration waveform is converted into the residual vibration pulse. The pulse width measurement value obtained by measuring the time corresponding to the pulse width of the residual vibration pulse is output. In addition, a reset signal and a load signal L1 are also output.

  The discharge abnormality detection circuit 110 is a normal determination signal based on the pulse width measurement value output from the residual vibration detection unit 106, the Load signal L1, and a normal discharge reference value (TR ± α) described later output from the control unit 102. And a bubble determination signal and a classification signal (see FIG. 18J). These output signals include a reset signal output from the residual vibration detection unit 106 and a classification circuit 112 described later. Is reset to "L level" by the sorting end signal output from the.

Based on the pulse width measurement value output from the residual vibration detection unit 106, the load signal L1, and the classification signal output from the ejection abnormality detection circuit 110, the classification circuit 112 generates a dry determination signal (see FIG. 18 (P)). A paper dust determination signal (see FIG. 18 (O)) and a sorting end signal (see FIG. 18 (Q)) are output.
Further, the residual vibration detection unit 106 includes a detection timing generation circuit 114, a changeover switch 116, a residual vibration detection circuit 118, and a pulse width measurement circuit 120 as a pulse width measurement unit.

The detection timing generation circuit 114 generates a drive / detection switching signal (see FIG. 18C) and a load signal L1 (see FIG. 18C) based on the pause signal output from the drive circuit 104 and the detection timing setting value output from the control unit 102. 18H) and a reset signal (see FIG. 18G) are output.
The changeover switch 116 has a movable contact, a normally closed contact, and a normally open contact. The movable contact is in the actuator 22, the normally closed contact is in the drive circuit 104, and the normally open contact is in the residual vibration detection circuit 118. It is connected. Normally, as shown in FIG. 10, when the contact is in a state where a movable contact and a normally closed contact are connected, and when an ink droplet ejection abnormality is detected, a drive / detection switching signal is output from the detection timing generation circuit 114. This is a switch for switching the contact from the normally closed contact to the normally open contact.

The residual vibration detection circuit 118 detects the change in the charging voltage Vc of the capacitor forming the actuator 22 by switching the switching contact of the changeover switch 116 to the normally open contact side when detecting an ink droplet ejection abnormality. Residual vibration of the diaphragm 21 is detected and a residual vibration pulse (see FIG. 18E) is output.
That is, in this embodiment, a change in the charging voltage of the actuator 22 is induced from the electric charge remaining in the actuator 22 and the capacitance of the actuator 22 that changes due to the displacement of the diaphragm 21. Therefore, the residual vibration detection circuit 118 detects the residual vibration of the diaphragm 21 from the induced change in the charging voltage of the actuator 22.

The pulse width measurement circuit 120 measures a time corresponding to the pulse width of the first pulse in the residual vibration pulse output from the residual vibration detection circuit 118, and outputs a pulse width measurement value (see FIG. 18F). It has become. The pulse width measurement value is reset to 0 by a reset signal output from the detection timing generation circuit 114.
Next, a specific configuration of the detection timing generation circuit 114 shown in FIG. 10 will be described with reference to FIG.

As shown in FIG. 11, the detection timing generation circuit 114 includes a counter 130, a coincidence comparator 131, a latch circuit 132 composed of, for example, an RS flip-flop circuit, a two-input AND 133, and an edge detector (falling edge). ) 134 and a delay circuit 135.
The counter 130 counts the timing at which the pause signal output from the drive circuit 104 rises from “L level” to “H level”, and outputs the count value to the coincidence comparator 131. Further, the count value of the counter 130 is reset to 0 by a reset signal output from a delay circuit 135 described later.

The coincidence comparator 131 compares the count value output from the counter 130 with the detection timing setting value output from the control unit 102. If they match, the “H” level signal is detected. An “L” level signal is output to the latch circuit 132.
The latch circuit 132 is set when the signal output from the coincidence comparator 131 is supplied as a set signal and becomes “H level”, and outputs an “H level” latch signal to the 2-input AND 133. Further, the latch signal of the latch circuit 132 is reset to “L level” by a reset signal output from the delay circuit 135 described later.

  The 2-input AND 133 receives the pause signal output from the drive circuit 104 and the latch signal output from the latch circuit 132, and when both are at the “H level”, the drive / detection of “H level”. In other cases, the switching signal is output to the changeover switch 116 and the edge detector (falling) 134 of the residual vibration detection unit 106 in the other cases.

The edge detector (falling edge) 134 detects the timing at which the drive / detection switching signal output from the 2-input AND 133 falls from “H level” to “L level”. L1 is output to the ejection abnormality detection circuit 110 and the sorting circuit 112.
The delay circuit 135 delays the pulse signal of the load signal L1 output from the edge detector (falling) 134 by a predetermined time and uses it as a reset signal as a counter 130, a latch circuit 132, a pulse width measurement circuit 120, and an ejection abnormality detection circuit. To 110.

Next, a specific configuration of the residual vibration detection circuit 118 shown in FIG. 10 will be described with reference to FIG.
When the actuator 22 is an electrostatic actuator, the residual vibration detection circuit 118 includes an oscillation circuit 140 including a capacitor such as a CR transmitter and an LC transmitter, and an F / V converter 141 as shown in FIG. And an AC amplifier 145 including a capacitor 142 and an amplifier 143, and a waveform shaping circuit 144.

  As shown in FIG. 6, the electrostatic actuator is considered as a capacitor in which the diaphragm 21 and the individual electrode 30 are parallel plates, and the electrostatic capacity changes due to the residual vibration of the diaphragm 21. By incorporating the electrostatic capacity of this electrostatic actuator into the oscillation circuit 140 and oscillating it, the oscillation output is converted into a voltage value by the F / V converter 141, and the AC component of this voltage value is amplified by the AC amplifier 145. A residual vibration waveform is output, and this residual vibration waveform is shaped into a residual vibration pulse by a waveform shaping circuit 144 including a Schmitt trigger circuit and the like, and is output to the pulse width measurement circuit 120.

The residual vibration detection circuit 118 when the actuator 22 is a piezoelectric actuator is a combination of an AC amplifier 145 including a capacitor 142 and an amplifier 143 and a waveform shaping circuit 144 as shown in FIG. Consists of.
In the piezoelectric actuator, an electromotive voltage is generated in the piezoelectric element due to a mechanical change of the diaphragm. The AC component of this electromotive voltage is amplified by an AC amplifier 145 to output a residual vibration waveform, which is shaped into a residual vibration pulse by a waveform shaping circuit 144 and output to the pulse width measurement circuit 120.

Next, a specific configuration of the pulse width measurement circuit 120 shown in FIG. 10 will be described with reference to FIG.
The pulse width measurement circuit 120 is the first of the residual vibration pulses output from the residual vibration detection circuit 118 which is a basis for performing the ejection abnormality (non-ejection) classification based on the classification principle described with reference to FIGS. Is configured as shown in FIG.

  This pulse width measuring circuit 120 includes a two-input AND 162 to which a residual vibration pulse output from the residual vibration detection circuit 118 and a clock pulse of a predetermined frequency output from the clock signal generation circuit 161 are input, and the residual vibration pulse is an inverter. An RS type flip-flop 164 to which a reset signal output from the detection timing generation circuit 114 is input to the reset terminal R is provided in the set terminal S via the H.163. The pulse width measurement circuit 120 counts the two-input AND 165 to which the output signal obtained from the negative output terminal QB of the RS flip-flop 164 and the output signal of the two-input AND 162 are input, and the output signal of the two-input AND 165. And a counter 166 whose count value is reset by a reset signal.

  In the pulse width measurement circuit 120, when the residual vibration pulse shown in FIG. 14A is input from the residual vibration detection circuit 118, when the residual vibration pulse becomes “H” level, the 2-input AND 162 changes to FIG. The clock signal is output as shown in FIG. On the other hand, since the pulse obtained by inverting the residual vibration pulse by the inverter 163 as shown in FIG. 14C is supplied to the RS flip-flop 164, the negative output terminal QB of the RS flip-flop 164 receives the pulse shown in FIG. ), When the inversion pulse becomes “H level”, a negative output that becomes “L level” is output and supplied to the two-input AND 165, so that this two-input AND 165 shows the result shown in FIG. Thus, since the clock signal corresponding to the first “H level” section of the residual vibration pulse is output and supplied to the counter 166, the count value of the counter 166 is the residual vibration as shown in FIG. It becomes a value corresponding to the first pulse width of the pulse, and this count value is the pulse width measurement value as the discharge abnormality detection circuit 110 and the classification circuit 112. Is output.

Next, a specific configuration of the ejection abnormality detection circuit 110 shown in FIG. 10 will be described with reference to FIG.
As shown in FIG. 15, the discharge abnormality detection circuit 110 is a latch composed of comparators 150 and 151, inverters 152 and 153, three-input AND 154, two-input AND 155 and 156, and an RS flip-flop circuit, for example. The circuit 157, 158 and 159 are combined.

The comparator 150 compares a pulse width measurement value T output from the pulse width measurement circuit 120 of the residual vibration detection unit 106 with a normal discharge reference value (TR + α) described later output from the control unit 102, and T> In the case of (TR + α), “H level” is output to the inverter 152 and the 2-input AND 156 in other cases.
The comparator 151 compares a pulse width measurement value T output from the pulse width measurement circuit 120 of the residual vibration detection unit 106 with a normal discharge reference value (TR-α) described later output from the control unit 102, When T <(TR−α), “H level” is output to inverter 153 and 2-input AND 155 otherwise.

  The three-input AND 154 is when both the signal obtained by inverting the output signal output from the comparator 150 by the inverter 152 and the signal obtained by inverting the output signal output from the comparator 151 by the inverter 153 are “H level”. When the “H level” pulse signal of the load signal L 1 output from the detection timing generation circuit 114 is input, “H level” is output to the latch circuit 157.

  The latch circuit 157 is supplied when the signal output from the 3-input AND 154 is supplied as a set signal, and is set to “H level”, and outputs the “H level” latch signal to the control unit 102 as a normal determination signal. To do. This means that the pulse width measurement value T is in the range of the normal ejection reference value (TR ± α), and ejection is normal. The latch signal of the latch circuit 157 is reset to “L level” by the reset signal output from the detection timing generation circuit 114.

When the output signal output from the comparator 151 is “H level”, the 2-input AND 155 is “when the pulse signal of“ H level ”of the load signal L1 output from the detection timing generation circuit 114 is input. "H level" is output to the latch circuit 158.
The latch circuit 158 is supplied when the signal output from the 2-input AND 155 is supplied as a set signal, and is set to “H level”, and outputs the “H level” latch signal to the control unit 102 as a bubble determination signal. To do. This means that the pulse width measurement value T is less than the lower limit (TR-α) of the normal ejection reference value, and the cause of ejection abnormality is due to air bubble mixing. The latch signal of the latch circuit 158 is reset to “L level” by the reset signal output from the detection timing generation circuit 114.

When the output signal output from the comparator 150 is “H level”, the 2-input AND 156 is “when the pulse signal of“ H level ”of the load signal L1 output from the detection timing generation circuit 114 is input. “H level” is output to the latch circuit 159.
The latch circuit 159 is set when the signal output from the two-input AND 156 is supplied as a set signal and becomes “H level”, and outputs the “H level” latch signal to the classification circuit 112 as a classification signal. . This is because the pulse width measurement value T exceeds the upper limit (TR + α) of the normal discharge reference value, the cause of the discharge abnormality is due to something other than air bubbles mixing, and it is determined that it is necessary to distinguish whether paper dust is abnormal or drying is abnormal It means to do. Further, the latch signal of the latch circuit 158 is reset to “L level” by the sorting end signal output from the sorting circuit 112.

Next, a specific configuration of the classification circuit 112 illustrated in FIG. 10 will be described with reference to FIG.
As shown in FIG. 16, the classification circuit 112 includes a storage circuit unit 190 that is a storage unit that stores the initial measurement value and the sequential measurement value measured by the pulse width measurement circuit 120 of the residual vibration detection unit 106, the initial measurement value, A comparison circuit unit 191 that is a comparison unit that sequentially compares measured values, a determination circuit unit 192 that is an abnormality determination unit that determines whether there is a paper dust abnormality or a drying abnormality from the comparison result in the comparison circuit unit 191, and a determination circuit unit 192 When the abnormality determination is performed, the drive circuit 104 and a drive stop circuit unit 193 that is a drive stop unit that stops driving the residual vibration detection unit 106 are configured.

Further, the memory circuit unit 190 includes an edge detector (rising edge) 170, a register (T) 171, a register (Tn) 172, a delay circuit 173, and a two-input AND 174.
Further, the comparison circuit unit 191 includes a comparator 175 and a comparator 176.
Further, the determination circuit unit 192 includes two-input ANDs 177 and 178 and latch circuits 179 and 180 formed of, for example, RS flip-flop circuits.

Further, the drive stop circuit unit 193 includes a two-input OR 181 and a delay circuit 182.
The edge detector (rising edge) 170 detects the timing at which the classification signal output from the ejection abnormality detection circuit 110 rises from “L level” to “H level”, and at this time of detection, a load signal L 0 (pulse signal L 0 ( 18K) is output to the register (T) 171.

The register (T) 171 stores the initial measurement value T of the pulse width measurement value output from the pulse width measurement circuit 120 of the residual vibration detection unit 106, and the load signal L0 output from the edge detector (rising) 170 as a set signal. Is set as “H”, and the initial measurement value T is output to the comparator 175 and the comparator 176.
The two-input AND 174 outputs a pulse signal of the load signal L1 output from the detection timing generation circuit 114 to the register (Tn) 172 and the delay circuit 173 when the classification signal output from the ejection abnormality detection circuit 110 is “H level”. Output to.

The register (Tn) 172 is supplied with the sequential measurement value Tn of the pulse width measurement value output from the pulse width measurement circuit 120 of the residual vibration detection unit 106, and the pulse signal output from the 2-input AND 174 is supplied as a set signal. It is set when it becomes “H level”, and the measurement value Tn is sequentially output to the comparator 175 and the comparator 176.
The delay circuit 173 delays the pulse signal output from the 2-input AND 174 for a predetermined time and outputs it to the 2-input ANDs 177 and 178 as a classification determination signal.

The comparator 175 compares the initial measurement value T output from the register (T) 171 with the sequential measurement value Tn output from the register (Tn) 172. If T <Tn, the comparator 175 sets “H level”. In other cases, “L level” is output to the 2-input AND 177.
The comparator 176 compares the initial measurement value T output from the register (T) 171 with the sequential measurement value Tn output from the register (Tn) 172. If T> Tn, the comparator 176 sets “H level”. In other cases, “L level” is output to the 2-input AND 178.

When the signal output from the comparator 175 is “H level”, the 2-input AND 177 is “H level” when the “H level” pulse signal of the classification determination signal output from the delay circuit 173 is input. Is output to the latch circuit 179.
The latch circuit 179 is set when the signal output from the two-input AND 177 is supplied as a set signal and becomes “H level”, and the control unit 102 sets the “H level” latch signal as a paper dust determination signal. Output to 2-input OR181. Further, the latch signal of the latch circuit 179 is reset to “L level” by the classification end signal output from the drive stop circuit unit 193.

When the signal output from the comparator 176 is “H level”, the 2-input AND 178 is “H level” when the “H level” pulse signal of the classification determination signal output from the delay circuit 173 is input. Is output to the latch circuit 180.
The latch circuit 180 is supplied when a signal output from the two-input AND 178 is supplied as a set signal and becomes “H level”, and the control circuit 102, 2 receives the “H level” latch signal as a drying determination signal. Output to the input OR 181. In addition, the latch signal of the latch circuit 180 is reset to “L level” by the classification end signal output from the drive stop circuit unit 193.

The 2-input OR 181 outputs “H level” when either the paper dust determination signal output from the latch circuit 179 or the drying determination signal output from the latch circuit 180 becomes “H level”. When both the determination signal and the drying determination signal are “L level”, “L level” is output to the delay circuit 182.
The delay circuit 182 delays the output signal of the 2-input OR 181 for a predetermined time and outputs it as a separation end signal to the latch circuits 179 and 180, the ejection abnormality detection circuit 110, and the control unit 102.

Next, the ejection abnormality detection process executed by the control unit 102 will be described based on the flowchart shown in FIG.
This discharge abnormality detection process is performed whenever necessary, such as when the power is turned on or when a large amount of images are formed on a recording sheet and each time a predetermined number of pages are formed.

First, in step S100, after selecting a nozzle for detecting a discharge abnormality, the process proceeds to step S102.
In step S102, the detection timing setting value (the number of shots) is set to “1”, and the process proceeds to step S104.
In step S104, the drive instruction signal is output to the drive circuit 104, and the process proceeds to step S106.

In step S106, it is determined whether or not any of the normality determination signal, the bubble determination signal, and the separation signal has become “H level” from the ejection abnormality detection circuit 110, and when it is not “H level” (No ) Waits until it becomes “H level”, and when it becomes “H level” (Yes), the process proceeds to step S108.
In step S108, it is determined whether or not the normality determination signal output from the ejection abnormality detection circuit 110 is “H level”. When it is determined that it is “H level” (Yes), the process proceeds to step S138. When it is determined that the level is not “H level” (No), the process proceeds to step S110.

In step S138, it is determined whether or not all nozzles have been detected. When it is determined that the nozzles have ended (Yes), the ejection abnormality detection process ends, and when it is determined that they have not ended (No). The process proceeds to step S100.
In step S110, it is determined whether or not the bubble determination signal output from the ejection abnormality detection circuit 110 is “H level”. When it is determined that the bubble determination signal is “H level” (Yes), the process proceeds to step S112. When it is determined that the level is not “H level” (No), the process proceeds to step S114.

In step S112, bubble recovery processing is performed, and the process proceeds to step S138.
In step S114, the detection timing setting value (the number of shots) is set to n, the maximum number of times for setting the number of times the process is repeated is set to m, the number of times M for counting the number of processes is set to “1”, The process proceeds to step S115.
In step S115, the number of shots S for counting the number of shots is set to “0”, and the process proceeds to step S116.

In step S116, the drive instruction signal is output to the drive circuit 104, and the process proceeds to step S118.
In Step S118, “1” is added to the Shot number S for counting the Shot number, and the process proceeds to Step S120.
In step S120, after outputting the drive instruction signal, it is determined whether or not a time period equal to or longer than the sum of the period in which the pause signal is “H” and the period in which the drive signal is on has elapsed. ) Goes to step S122, and when it is determined that it has not elapsed (No), it waits until it elapses.

In step S122, it is determined whether or not the number of shots S = n. When it is determined that the number of shots S = n (Yes), the process proceeds to step S124, and when it is determined that the number of shots S = n is not satisfied (No) ) Proceeds to step S116.
In step S124, it is determined whether or not either the paper dust determination signal or the drying determination signal from the separation circuit 112 has become "H level". If the signal has not become "H level" (No). When the process proceeds to step S125 and becomes “H level” (Yes), the process proceeds to step S126.

In step S125, it is determined whether or not a predetermined time has elapsed. When it is determined that the predetermined time has elapsed (Yes), the process proceeds to step S134, and when it is determined that the predetermined time has not elapsed (No), The process proceeds to S124.
In step S126, it is determined whether or not the paper dust determination signal output from the sorting circuit 112 is “H level”. When it is determined that it is “H level” (Yes), the process proceeds to step S128. When it is determined that the level is not “H level” (No), the process proceeds to step S130.

In step S128, paper dust recovery processing is performed, and the process proceeds to step S138.
In step S130, it is determined whether or not the drying determination signal output from the separation circuit 112 is “H level”. When it is determined that the drying determination signal is “H level” (Yes), the process proceeds to step S132, and “ When it is determined that the level is not “H” (No), the process proceeds to step S134.
In step S132, a drying recovery process is performed, and the process proceeds to step S138.

In step S134, it is determined whether or not the processing count M = m. If it is determined that the processing count M = m (Yes), the process proceeds to step S136, and if it is determined that the processing count M = m is not satisfied (No) ) Proceeds to step S140.
In step S136, a process is performed when the cause of the ejection abnormality cannot be separated, and the process proceeds to step S138.

In step S140, “1” is added to the number of processes M for counting the number of processes, and the process proceeds to step S115.
The operation when an electrostatic actuator is applied as the actuator of the above embodiment will be described with reference to a timing chart shown in FIG.
In FIG. 18, the case where paper dust adheres to a certain nozzle and it is determined that paper dust is abnormal is roughly dried. To simplify the description, the detection timing setting value (Shot number) set by the control unit 102 is shown. Is set to n = 3, and the maximum number of times is set to m = 5.

Now, the discharge abnormality detection process shown in FIG. 17 is executed at a predetermined timing, that is, when the printer is turned on by the control unit 102, when a print start command is input, or when a predetermined number of prints are completed during printing.
In this ejection abnormality detection process, first, a nozzle to be detected is selected (step S100), and then a detection timing set value n is set to “1”, and then a drive instruction signal is output to the drive circuit 104.

Therefore, as shown in FIG. 18A, the drive circuit 104 outputs a drive signal at time t1. Since the pause signal shown in FIG. 18B is “L” during the period when the drive signal is on, the counter 130 does not count and the drive / detection switching signal output from the 2-input AND 133 is also shown in FIG. The "L level" is maintained as shown in FIG.
Therefore, since the changeover switch 116 of the residual vibration detection unit 106 is switched to the drive circuit 104 side and the drive circuit 104 and the actuator 22 are connected, the drive signal output from the drive circuit 104 is an electrostatic actuator. The ink droplets are ejected by being applied to 22 and vibrating the diaphragm 21.

  After that, when the drive signal is turned off at time t2, the pause signal becomes “H level” accordingly, and this is supplied to the counter 130 and the two-input AND 133. For this reason, the counter 130 is counted up and the count value becomes “1”, and the detection timing set value in which the count value is set to “1” is supplied to the input match comparator 131. The comparator 131 outputs an “H level” coincidence signal, which is latched by the latch circuit 132 and supplied to the two-input AND 133. For this reason, as shown in FIG. 18C, the drive / detection switching signal output from the two-input AND 133 becomes “H level” at the time point t 2 and is supplied to the changeover switch 116. Is switched to the residual vibration detection circuit 118 side, and a capacitor constituted by the individual electrode 30 of the electrostatic actuator 22 and the diaphragm 21 is incorporated in the oscillation circuit 140 of the residual vibration detection circuit 118.

Therefore, an oscillation signal corresponding to the residual vibration waveform is output from the oscillation circuit 140, which is converted into a voltage signal by the F / V converter 141, and then amplified by an AC amplifier, and the residual vibration waveform shown in FIG. It becomes.
By supplying this residual vibration waveform to the waveform shaping circuit 144, the residual vibration that becomes “H level” at the time t3 when the residual vibration waveform shown in FIG. 18E from the waveform shaping circuit 144 exceeds a predetermined threshold value. A pulse is formed and output to the pulse width measuring circuit 120.

For this reason, in the pulse width measurement circuit 120, as described above, the counter 166 counts the clock signal corresponding to the first pulse width of the residual vibration pulse, so that the first of the residual vibration pulses shown in FIG. A pulse width measurement value T that increases in the pulse width section is output.
At this time, assuming that a paper dust abnormality has occurred in the nozzle that is an abnormality detection target, the pulse width of the first pulse in the residual vibration pulse is longer than the normal value, so the pulse width measurement value T is the normal discharge range. Of the normal discharge range exceeds the upper limit value TR + α at time t5, and reaches the maximum value at time t6 when the residual vibration pulse becomes “L level”.

  Since this pulse width measurement value T is supplied to the discharge abnormality detection circuit 110, when the pulse width measurement value T is less than the lower limit value TR-α of the normal discharge range in the discharge abnormality detection circuit 110, the comparator 150 The comparator 151 becomes “H level”, the comparator 151 becomes “H level”, and thereafter the comparators 150 and 151 both become “L level” between time t4 and time t5 where TR−α ≦ T ≦ TR + α, and the pulse width measurement value T At time t5 when the value exceeds the upper limit value TR + α of the normal discharge range, the output of the comparator 150 becomes “H level” as shown in FIG. 18I, and the comparator 151 maintains “L level”.

  Thereafter, when the pause signal output from the drive circuit 104 at the time t7 after the lapse of a predetermined time from the time t2 becomes “L” level as shown in FIG. 18B, the detection timing generation circuit 114 2 The drive / detection switching signal output from the input AND 133 becomes “L” level as shown in FIG. 18C, whereby the changeover switch 116 is switched to the drive circuit 104 side. At the same time, the load signal L 1 shown in FIG. 18H is output from the edge detector 134 of the detection timing generation circuit 114 to the ejection abnormality detection circuit 110 and the classification circuit 112.

  For this reason, in the discharge abnormality detection circuit 110, the load signal L1 is supplied to the three-input AND 154 and the two-input ANDs 155 and 156. At this time t7, the output of the comparator 150 is “H level” as described above. Since the output of the comparator 151 is “L level” and “H level” is input only to the 2-input AND 156, only the output of this 2-input AND 156 becomes “H level”, which is latched by the latch circuit 159. Then, the latch circuit 159 outputs a classification signal that becomes “H level” shown in FIG. 18 (J), and supplies this to the classification circuit 112.

  Therefore, since the classification signal is supplied to the edge detector 170 and the two-input AND 174 in the classification circuit 112, it becomes “H level” at the rising edge of the classification signal shown in FIG. A Load signal L 0 that is subsequently set to “L level” is output to the register 171. Therefore, the register 171 stores the pulse width measurement value T as the initial pulse width measurement value T0 as shown in FIG. 18 (L) at the time t7 when the load signal L0 is input. At this time, since the classification signal and the load signal L1 are supplied to the two-input AND 174, the output of the two-input AND 174 becomes “H level”, and this is supplied to the register 172. The value T is stored.

  However, since the same pulse width measurement value T is stored in the registers 171 and 172, both the comparators 175 and 176 maintain "L level", so that the outputs of the two-input ANDs 177 and 178 are "L level". Accordingly, the paper dust determination signal and the drying determination signal, which are latch outputs of the latch circuits 179 and 180, also maintain the “L level” as shown in FIGS. Thereafter, a reset signal obtained by delaying the load signal L1 for a predetermined time is output from the delay circuit 135 of the detection timing generation circuit 114 at time t8, and the counter 130 and the latch circuit 132 of the detection timing generation circuit 114 are reset by this reset signal. At the same time, the latch circuits 157 and 158 except for the latch circuit 159 of the ejection abnormality circuit 110 are reset, and further, the RS flip-flop 164 of the pulse width measurement circuit 120 is reset.

On the other hand, at the time t7, the control unit 102 outputs a classification signal from the ejection abnormality detection circuit 110 and inputs this, so that the abnormality detection target nozzle is not normal and is in an abnormal state, and is not a bubble abnormality but a drying abnormality and It is determined that any paper dust abnormality has occurred, and the process proceeds from step S108 to step S114 through step S110.
For this reason, the detection timing setting value is set to n = 3, and the maximum number of times is set to m = 5. Then, the process proceeds to step S116 through step S115, and the drive instruction signal is output to the drive circuit 104.

For this reason, a drive signal is output from the drive circuit 104 as shown in FIG. 18A, and this is supplied to the electrostatic actuator 22 via the changeover switch 116, and an ink droplet discharge operation is performed. When the drive signal is turned off at time t9 which is later than time t8 when the signal is output, the pause signal becomes “H level”.
At this time, in the detection timing generation circuit 114, the counter 130 counts up and the count value becomes “1” when the pause signal becomes “H level”, but the coincidence comparator 131 receives “3” from the control unit 102. Since the detection timing set value set to "" is input, the output of the coincidence comparator 131 is maintained at "L level", and the latch circuit 132 is set to "L level" by the reset signal output at time t8. Since it has been reset, the drive / detection switching signal output from the 2-input AND 133 also maintains the “L level” as shown in FIG.

For this reason, the operations of the residual vibration detection circuit 118, the pulse width measurement circuit 120, the ejection abnormality detection circuit 110, and the classification circuit 112 are stopped, and only the classification signal of the ejection abnormality detection circuit 110 continues to be “H level”.
Thereafter, the driving instruction signal is output again from the control unit 102 at a time t10 when a predetermined time set equal to the time when the pause signal returns from “H level” to “L level” from the time t7. In this case as well, at time t7, a drive signal is supplied from the drive circuit 104 to the electrostatic actuator 22, whereby ink droplets are ejected. Thereafter, when the pause signal becomes “H level”. The counter 130 of the detection timing generation circuit 114 is counted up and the count value becomes “2”, but does not coincide with the detection timing setting value, so that the drive / detection switching signal maintains “L level” and remains. The vibration detection circuit 118, the pulse width measurement circuit 120, the ejection abnormality detection circuit 110, and the classification circuit 112 are not in operation, and only the determination signal of the classification circuit 112 continues to be “H level”.

  Thereafter, the drive instruction signal is output again from the control unit 102 at time t11 when the above-described predetermined time has elapsed from time t10. In this case as well, the ink droplets are ejected by supplying the drive signal from the drive circuit 104 to the electrostatic actuator 22 in the same manner as at time t7, but then the pause signal becomes “H level” at time t12. When the counter 130 of the detection timing generation circuit 114 is counted up, the count value becomes “3”. For this reason, the output signal of the coincidence comparator 131 becomes “H level”, and the drive / detection switching signal becomes “H level” from the two-input AND 133 as shown in FIG. Similarly, the ejection abnormality detection circuit 110, the pulse width measurement circuit 120, and the classification circuit 112 are driven to detect residual vibration of the electrostatic actuator 22.

  At this time, the ink droplet ejection operation has been performed three times since the previous pulse width measurement, and the ink droplets ejected from the nozzles propagated through the paper dust and oozed out in the lateral direction, forming an ink reservoir. However, if the amount of ink seepage contacting the nozzle is extremely small, there is almost no change in the acoustic impedance of the nozzle, and a pulse width measurement value T1 equal to the previous measurement is obtained.

For this reason, when the load signal L1 output from the detection timing generation circuit 114 at time t13 becomes “H level” as shown in FIG. 18H, the output of the 2-input AND 174 of the classification circuit 112 becomes “H level”. Thus, the pulse width measurement value T1 is sequentially stored in the register 172 as the pulse width measurement value Tn.
Also in this case, since the initial pulse width measurement value T0 stored in the register 171 is equal to the sequential pulse width measurement value Tn stored in the current register 172, the comparison outputs of the comparators 175 and 176 are “L level”. The paper dust determination signal and the drying determination signal output from the latch circuits 179 and 180 are also maintained at the “L level”.

For this reason, when the processing unit 102 outputs the drive signal three times, the process proceeds from step S122 to step S124, and when the paper dust determination signal and the drying determination signal are read, both are at the “L level”. Therefore, the process proceeds to step S125, and step S124 is repeated until a predetermined time elapses.
After that, both the paper dust determination signal and the drying determination signal continue to be at “L level” even after the predetermined time has elapsed. Therefore, the process proceeds to step S134, and the process number M = 1, so the process proceeds to step S140 and the process number M Becomes "2", returns to step S116 via step S115, and outputs a drive instruction signal in the same manner as at time t7 described above. The counter 130 is reset to zero.

  After the drive instruction signal is output three times from time t13, the count value of the counter 130 becomes “3” at time t14, the output signal of the coincidence comparator 131 becomes “H level”, and the 2-input AND 133 As shown in FIG. 18C, the drive / detection switching signal output from the “H” level is driven, and the ejection abnormality detection circuit 110, the pulse width measurement circuit 120, and the classification circuit 112 are driven in the same manner as at the time point t2. Then, the residual vibration of the electrostatic actuator 22 is detected.

At this time, the ink droplet ejection operation has been performed three times since the previous pulse width measurement, and the ink droplets ejected from the nozzles propagated through the paper dust and oozed out in the lateral direction, forming an ink reservoir. If the amount of ink oozing out in contact with the nozzles increases, the acoustic impedance of the nozzles changes, and a pulse width measurement value T2 larger than that at the previous measurement is obtained.
Therefore, when the load signal L1 output from the detection timing generation circuit 114 at time t15 becomes “H level” as shown in FIG. 18H, the output of the 2-input AND 174 of the classification circuit 112 becomes “H level”. Thus, the pulse width measurement value T2 is sequentially stored in the register 172 as the pulse width measurement value Tn.

  In this case, since the sequential pulse width measurement value Tn stored in the register 172 is larger than the initial pulse width measurement value T0 stored in the register 171, the output of the comparator 175 is shown in FIG. It becomes “H level”. When the classification determination signal becomes “H level” at time t16 as shown in FIG. 18N, the output of the 2-input AND 177 becomes “H level”, which is latched by the latch circuit 179, and the paper dust determination signal becomes “H”. Level ". Further, the comparison output of the comparator 176 maintains “L level”, the output of the two-input AND 178 also maintains “L level”, and the drying determination signal output from the latch 180 also maintains “L level”.

For this reason, the processing unit 102 shifts from step S122 to step S124 when the drive signal is output three times, determines that there is a determination input, shifts to step S126, and the paper dust determination signal is “H”. It is determined that there is “level”, the process proceeds to step 128, and paper dust recovery processing is executed.
Here, a specific configuration and method of the wiping process, which is an appropriate process as the recovery process in the paper dust adhesion state, will be described with reference to FIG.

Here, the wiping process refers to a process of wiping off foreign matters such as paper dust attached to the nozzle substrate 26 (nozzle surface) of the inkjet head 20 with the wiper 13.
FIG. 22 is a diagram showing a positional relationship between the wiper 13 and the head unit 2 shown in FIG. In FIG. 22, the head unit 2 and the wiper 13 are shown as a part of a side view when the upper side is viewed from the lower side of the inkjet printer 1 shown in FIG. As shown in FIG. 22A, the wiper 13 is arranged so as to be movable up and down so as to be in contact with the nozzle surface of the head unit 2, that is, the nozzle substrate 26 of the inkjet head 20.

  Here, a wiping process that is a recovery process using the wiper 13 will be described. When performing the wiping process, as shown in FIG. 22A, the wiper 13 is moved upward by a driving device (not shown) so that the tip of the wiper 13 is positioned above the nozzle surface (nozzle substrate 26). In this case, when the motor 6 is driven to move the head unit 2 in the left direction (the direction of the arrow) in the drawing, the wiping member 35 comes into contact with the nozzle substrate 26 (nozzle surface).

  Since the wiping member 35 is composed of a flexible rubber member or the like, as shown in FIG. 22B, the tip portion of the wiping member 35 that comes into contact with the nozzle substrate 26 bends, and the nozzle substrate is bent by the tip portion. Clean the surface of 26 (nozzle surface). This makes it possible to remove foreign matters such as paper dust (for example, paper dust, dust floating in the air, rubber scraps, etc.) adhering to the nozzle substrate 26 (nozzle surface). Further, depending on the state of foreign matter attachment (when many foreign matters are attached), the head unit 2 can be reciprocated above the wiper 13 to perform the wiping process a plurality of times. .

  At time t16, the 2-input OR circuit 181 of the sorting circuit 112 outputs “H level” in response to the “H level” signal of the paper dust determination signal, and after a predetermined time has elapsed by the delay circuit 182, FIG. Thus, the separation end signal is output at “H level”, the values of the latch circuits 179 and 180 are set to “L level”, the value of the latch circuit 159 of the ejection abnormality detection circuit 110 is set to “L level”, and the control unit 102, the discharge abnormality detection process for this nozzle is terminated, and the process proceeds to step 138. It is determined whether the detection of all the nozzles is completed. If it is determined that the nozzles have not been completed, the process proceeds to step S100. The same processing is repeated for another nozzle.

  As described above, in the case of paper dust abnormality, the pulse width measurement value T0 of the residual vibration waveform output from the electrostatic actuator 22 at time t6 of the drive / detection switching signal in FIG. Since the value exceeds the upper limit value TR + α, it is determined by the discharge abnormality detection circuit 110 that it is a cause other than air bubble mixing, and the pulse width measurement value T1 for the period of time t10 measured every three discharge operations. Then, the pulse width measurement value T2 at the next time t13 tends to increase as T0 <T2, and the sorting circuit 112 determines that paper dust is abnormal.

Next, the operation in the case where it is determined that the abnormality is dry will be briefly described with reference to FIG. As in the case of the paper dust abnormality described above, it is assumed that the detection timing setting value (Shot number) is set to n = 3 and the maximum number of times is set to m = 5.
At the time point t1, the drive signal in FIG. 19A is output, and at the time point t2, the drive signal is turned off. At the same time, the pause signal in FIG. 19B becomes “H level”, and the drive signal in FIG. The detection switching signal becomes “H level”, and the residual vibration waveform in FIG. 19D is detected. The residual vibration pulse of FIG. 19E is output by the residual vibration detection circuit 118, and the pulse width measurement value of FIG. 19F is output by the pulse width measurement circuit 120. The measured pulse width starts at time t3, exceeds the lower limit value TR-α of the normal discharge reference value at time t4, exceeds the upper limit value TR + α at time t5, and residual vibration of FIG. 19 (E) at time t6. Since the pulse became “L level”, the measurement was completed, and the measured pulse width was measured as T0. Since the output of the comparator 150 in FIG. 19 (I) becomes “H level” and the output of the comparator 151 is “L level” at time t5, the time t7 when the pause signal in FIG. 19 (B) becomes “L level”. Thus, the load signal L1 in FIG. 19H outputs a signal of “H level”, and the classification signal of FIG. 19J becomes “H level”. The Load signal L0 in FIG. 19K also becomes “H level”, and T0 is set as the initial measurement value T in the register 171.

  Since the classification signal has become “H level”, the process proceeds to step S114, and the three drive signals in FIG. 19A are output from time t7. At time t12, the drive / detection switching signal in FIG. Becomes “H level”, the residual vibration waveform in FIG. 19D is measured, the measured pulse width value in FIG. 19F is measured as T1, and T1 is sequentially set in the register 172 as the measured value Tn. Since the initial measurement value T0 and the sequential measurement value T1 are equal, and the comparators 175 and 176 are both “L level”, both the paper dust determination signal and the drying determination signal are maintained at “L level”, and steps S134 and S140 are performed. Then, the process proceeds to step S115.

  19A is output from time t13, and the drive / detection switching signal in FIG. 19C becomes “H” level at time t14, and the residual vibration waveform in FIG. 19D is measured. Then, the measured pulse width value in FIG. 19F is measured as T2, and T2 is sequentially set in the register 172 as the measured value Tn. Since the droplet discharge operation has been performed with the drive signal six times from time t7, the viscosity of the ink near the nozzles decreases, and the measured value T2 tends to decrease sequentially with respect to the initial measured value T0. ) Of the comparator 176 at time t15 becomes “H level”. At time t16, the classification determination signal in FIG. 19 (N) becomes “H level”, and the drying determination signal in FIG. 19 (Q) becomes “H level”.

For this reason, in the process part 102, when driving signal is output 3 times, it transfers to step S124 from step S122, it determines with having received the determination input, it transfers to step 130 through step S126, and a dry determination signal Is determined to be at the “H level”, the process proceeds to step 132, and the drying recovery process is executed.
Here, a specific configuration and method of the pumping process (pump suction process), which is an appropriate process for recovering the ejection abnormality due to the drying of the nozzles, will be described with reference to FIGS.

  FIG. 23 and FIG. 24A are diagrams showing the relationship between the head unit 2, the cap 14, and the tube pump 40 during the pump suction process. The tube 42 forms an ink discharge path in the pumping process (pump suction process), and one end thereof is connected to the bottom of the cap 14 as described above, and the other end is discharged via the tube pump 40. The ink cartridge 47 is connected.

  An ink absorber 41 is disposed on the inner bottom surface of the cap 14. The ink absorber 41 absorbs the ink discharged from the nozzles 24 of the inkjet head 20 in the pump suction process and the flushing process, and temporarily stores the ink. The ink absorber 41 can prevent the ejected droplets from splashing and soiling the nozzle substrate 26 during the flushing operation into the cap 14.

  FIG. 24B is a schematic diagram showing the configuration of the tube pump 40 shown in FIG. As shown in FIG. 24B, the tube pump 40 is a rotary pump, and includes a rotating body 43, four rollers 44 disposed on a circumferential portion of the rotating body 43, and a guide member 45. I have. The roller 44 is supported by the rotating body 43 and presses the flexible tube 42 placed in an arc along the guide 46 of the guide member 45.

  In this tube pump 40, one or two rollers 44 in contact with the tube 42 are moved in the Y direction by rotating the rotating body 43 about the shaft 43a in the direction of the arrow X shown in FIG. The tube 42 placed on the arcuate guide 46 of the guide member 45 is sequentially pressurized while rotating. As a result, the tube 42 is deformed, and the ink (liquid material) in the cavity 23 of each inkjet head 20 is sucked through the cap 14 due to the negative pressure generated in the tube 42, and bubbles are mixed in or dried. Unnecessary ink thickened due to the ink is discharged to the ink absorber 41 via the nozzle 24, and the waste ink absorbed by the ink absorber 41 is discharged to the waste ink cartridge 47 (see FIG. 23) via the tube pump 40. Discharged.

  The tube pump 40 is driven by a motor such as a pulse motor (not shown). The pulse motor is controlled by the control unit 102. Drive information for the rotation control of the tube pump 40, for example, a look-up table in which the rotation speed and the number of rotations are described, a control program in which sequence control is described, and the like are stored in the ROM 126 of the control unit 102. The tube pump 40 is controlled by the CPU 124 of the control unit 102 based on the drive information.

Next, an operation for a case where it is determined to be normal will be briefly described with reference to FIG.
At time t1, the drive signal in FIG. 20A is output, and at time t2, the drive signal is turned off. At the same time, the pause signal in FIG. 20B becomes “H level”, and the drive / signal in FIG. The detection switching signal becomes “H level”, and the residual vibration waveform in FIG. 20D is detected. The residual vibration pulse of FIG. 20E is output by the residual vibration detection circuit 118, and the pulse width measurement value of FIG. 20F is output by the pulse width measurement circuit 120. The pulse width measurement value starts from time t3, exceeds the value of the lower limit value TR-α of the normal discharge reference value at time t4, and the residual vibration pulse in FIG. 20 (E) becomes “L level” at time t5. The measurement was completed, and the pulse width measurement value was measured as T0. At time t5, the output of the comparator 150 in FIG. 20I becomes “L level” and the output of the comparator 151 in FIG. 20J is “L level”. Therefore, the pause signal in FIG. The load signal L1 of FIG. 20 (H) outputs a signal of “H level” at time t7 when “L level” is reached, and the normality determination signal of FIG. 20 (R) becomes “H level”.

The control unit 102 determines that the normal determination signal is “H level” (step S108), and proceeds to step 138.
Next, the operation when it is determined that the bubble is abnormal will be briefly described with reference to FIG.
At time t1, the drive signal in FIG. 21A is output, and at time t2, the drive signal is turned off. At the same time, the pause signal in FIG. 21B becomes “H level”, and the drive / signal in FIG. The detection switching signal becomes “H level”, and the residual vibration waveform of FIG. The residual vibration pulse of FIG. 21E is output by the residual vibration detection circuit 118, and the pulse width measurement value of FIG. 21F is output by the pulse width measurement circuit 120. The measurement of the pulse width measurement value starts from time t3, and the residual vibration pulse in FIG. 21E becomes “L” level at time t4. Therefore, the measurement is completed, and the pulse width measurement value is measured as T0. As shown in FIG. 21F, the pulse width measurement value T0 is lower than the lower limit value TR-α of the normal ejection reference value. Since the output of the comparator 150 in FIG. 21I is “L level” and the output of the comparator 151 in FIG. 21J is “H level” at the time t4, the pause signal in FIG. The load signal L1 in FIG. 21 (H) outputs a signal at “H level” at time t7 when “L level” is reached, and the bubble determination signal in FIG. 21 (S) becomes “H level”.

The control unit 102 determines that the bubble determination signal is “H level” (step S110), and performs bubble recovery processing (step S112). In the bubble recovery process, a pumping process (pump suction process) is performed.
Next, the operation for the case where it is determined that separation is not possible will be briefly described with reference to FIG. As in the case of the paper dust abnormality described above, it is assumed that the detection timing setting value (Shot number) is set to n = 3 and the maximum number of times is set to m = 5.

  It is determined that classification is not possible after the classification signal of FIG. 18 (J) becomes “H level” at time t7 with respect to the pulse width measurement value T0 of FIG. 18 (F) measured at time t7. The state in which the pulse width measurement value Tn at the time t13 measured after the drive signal is output three times does not change, and both the paper dust determination signal and the drying determination signal maintain “L level” is processed five times. Even if it does not change, the control part 102 determines with the process frequency M = 5 (step S134), and a classification impossibility process is performed (step S136).

In the non-separable process, a wiping process and a pumping process (pump suction process) are performed, and if it still does not recover, it is treated as a head unit failure.
In the present invention, when the changeover switch 116 switches from the drive circuit 104 to the residual vibration detection circuit 118 in order to detect residual vibration, and separation processing for paper powder abnormality or drying abnormality is performed, the separation is performed. Therefore, it is better to set a larger detection timing setting value (number of shots) in consideration of the number of times of switching.

Also, if paper dust abnormality is detected with one nozzle, the wiping process described later is performed, so even if paper dust abnormality occurs with other nozzles, it can be wiped off at the same time, so other paper dust abnormality is judged normal The probability of being done is high. Even in the case of drying, all the nozzles are sucked by the suction processing described later, so the same can be said, and the entire processing time is shortened.
In the description of the present embodiment, the detection timing setting value (Shot number) is set to 3. However, for example, if the detection timing setting value (Shot number) is set to 1, discharge abnormality detection is performed after each discharge operation. When the ejection abnormality can be determined, the ejection abnormality detection operation can be completed. Therefore, ink droplet ejection is not performed wastefully, and ink consumption can be suppressed. In addition, since the processing time for one nozzle can be saved, the processing time for the discharge abnormality detection work for all the nozzles can be shortened.

Next, an embodiment in which the CPU 124 performs processing based on a program stored in a predetermined area of the ROM 126 of the control unit 102 will be described with reference to FIGS. 29 to 33.
In this embodiment, as shown in FIG. 29, a control unit 102 that controls the entire system, a drive circuit 104 as a drive unit that drives the actuator 22 by a drive instruction signal output from the control unit 102, and an actuator 22 And a residual vibration detecting unit 106 as residual vibration detecting means for detecting the residual vibration.

The residual vibration detection unit 106 includes a changeover switch 116 and a residual vibration detection circuit 118.
In addition, the control unit 102 includes a CPU 124 that controls computation and the entire system based on a control program, a ROM 126 that stores a CPU control program and the like in a predetermined area, data read from the ROM, and a CPU computation process. The RAM 128 is used to store necessary calculation results.

The CPU 124 includes a microprocessing unit (MPU) or the like, starts a predetermined program stored in a predetermined area of the ROM 126, and executes the ejection abnormality detection process shown in the flowchart of FIG. 30 according to the program. ing.
Next, the ejection abnormality detection process executed by the control unit 102 will be described based on the flowchart shown in FIG.

First, in step S200, after selecting a nozzle for detecting a discharge abnormality, the process proceeds to step S202.
In step S202, the drive instruction signal is output to the drive circuit 104, and the process proceeds to step S204.
In step S204, the pause signal output from the drive circuit 104 is checked to determine whether or not the pause signal has risen from "L level" to "H level". Waits until it rises, and when it falls (Yes), the process proceeds to step S206.

In step S206, the pulse width measurement process shown in FIG. 31 is executed, and then the process proceeds to step S208.
In step S208, after performing the discharge abnormality determination process shown in FIG. 32, the process proceeds to step S210.
In step S210, it is determined whether or not the value of the normality determination flag held in the RAM 128 by the ejection abnormality determination process is set to “1”, and when it is determined that it is set to “1” (Yes). The process proceeds to step S212, and when it is determined that “1” is not set (No), the process proceeds to step S214.

In step S212, it is determined whether or not the detection of all the nozzles has been completed. When it is determined that the detection has been completed (Yes), the ejection abnormality detection process is ended, and when it is determined that the detection has not been completed (No). The process proceeds to step S200.
In step S214, it is determined whether or not the value of the bubble determination flag held in the RAM 128 by the discharge abnormality determination process is set to “1”, and when it is determined that it is set to “1” (Yes). The process proceeds to step S216, and when it is determined that “1” is not set (No), the process proceeds to step S218.

In step S216, bubble recovery processing is performed, and the process proceeds to step S212.
In step S218, the paper dust / dry separation process shown in FIG. 33 is executed, and then the process proceeds to step S212.
Next, as shown in FIG. 31, in the pulse width measurement process in step 206, first, in step S230, the drive / detection switching signal is switched to “H level”, output to the changeover switch 116, and the process proceeds to step S232. .

In step S232, the value of the pulse width measurement value T is set to “0”, and the process proceeds to step S234.
In step S234, the residual vibration pulse output from the residual vibration detection circuit 118 is checked to determine whether or not the residual vibration pulse has risen from "L level" to "H level". If (No), it waits until it falls, and if it rises (Yes), it proceeds to step S236.

In step S236, the current time is set as Ts as the start time, and the process proceeds to step S238.
In step S238, the residual vibration pulse output from the residual vibration detection circuit 118 is checked to determine whether or not the residual vibration pulse has fallen from "H level" to "L level". In step S240, the process proceeds to step S239 when the process does not fall (No).

In step S239, the pause signal output from the drive circuit 104 is checked to determine whether or not the pause signal has fallen from "H level" to "L level". The process proceeds to S240, and when it does not fall (No), the process proceeds to Step S238.
In step S240, the current time is set as Te as the end time, and the process proceeds to step S242.

In step S242, a value of (Te−Ts) is set in the pulse width measurement value T, the value is held in the RAM 128, and the process proceeds to step S244.
In step S244, the drive / detection switching signal is switched to “L level” and output to the changeover switch 116, and the pulse width measurement process is terminated.
Next, as shown in FIG. 32, in the discharge abnormality determination process in step 208, first, in step S250, the values of the normal determination flag, the bubble determination flag, and the classification determination flag are reset to “0”, and the process proceeds to step S252. To do.

In step S252, the value of the pulse width measurement value T held in the RAM 128 is compared with the upper limit value TR + α of the normal ejection reference value stored in the ROM 126, and when it is determined that T> TR + α (Yes ), The process proceeds to step S254. If it is determined that T> TR + α is not satisfied (No), the process proceeds to step S256.
In step S254, the value of the classification determination flag is set to “1”, held in the RAM 128, and the ejection abnormality determination process ends.

In step S256, the value of the pulse width measurement value T held in the RAM 128 is compared with the lower limit value TR-α of the normal discharge reference value stored in the ROM 126, and when it is determined that T <TR-α (Yes ), The process proceeds to step S258, and when it is determined that T <TR-α is not satisfied (No), the process proceeds to step S260.
In step S258, the value of the bubble determination flag is set to “1”, held in the RAM 128, and the ejection abnormality determination process ends.

In step S260, the value of the normality determination flag is set to “1”, held in the RAM 128, and the ejection abnormality determination process ends.
Next, the paper dust / dry separation process of step S218 will be described based on the flowchart shown in FIG.
In the following description, the value of ΔT is stored in the ROM 126 as the allowable width of the difference between the initial measurement value of the pulse width measurement value and the sequential measurement value.

First, in step S270, the detection timing setting value (Shot number) stored in the ROM 126 is set in n, the maximum number of processing times stored in the ROM 126 is set in m, and the process proceeds to step S272.
In step S272, the initial measurement value T0 is set to the pulse width measurement value T measured by the pulse width measurement process and stored in the RAM 128, and the process proceeds to step S274.

In step S274, “1” is set in M for counting the current number of processes, and the process proceeds to step S276.
In step S276, “0” is set in S for counting the current number of shots, and the process proceeds to step S278.
In step S278, “1” is added to the current value of the number of shots S, and the process proceeds to step S280.

In step S280, the drive instruction signal is output to the drive circuit 104, and the process proceeds to step S282.
In step S282, the current value of the number of shots S is compared with the value of the detection timing setting value (number of shots) n. When it is determined that S = n (Yes), the process proceeds to step S286. When it is determined that S is not n (No), the process proceeds to step S284.

In step S284, the process waits until a predetermined time has passed (more than the time obtained by adding the period in which the pause signal is “H level” and the period in which the drive signal is on), and the process proceeds to step S278.
In step S286, the pause signal output from the drive circuit 104 is checked to determine whether or not the pause signal has risen from “L level” to “H level”. Waits until it rises, and when it rises (Yes), it proceeds to step S288.

In step S288, a pulse width measurement process is executed, and the process proceeds to step S290.
In step S290, the value of the pulse width measurement value T that is sequentially measured and stored in the RAM 128 is set as the measurement value Tn, and the process proceeds to step S292.
In step S292, the value of the initial measurement value T0 and the value of the measurement value Tn are sequentially compared. When it is determined that ΔT <Tn−T0 (Yes), the process proceeds to step S294, and ΔT <Tn−. When it is determined that it is not T0 (No), the process proceeds to step S296.

In step S294, a paper dust recovery process is performed, and the paper powder / dry separation process ends.
In step S296, the value of the initial measurement value T0 and the value of the measurement value Tn are compared sequentially. If it is determined that ΔT <T0−Tn (Yes), the process proceeds to step S298, and ΔT <T0− When it is determined that it is not Tn (No), the process proceeds to step S300.
In step S298, a drying recovery process is performed, and the paper dust / dry sorting process is terminated.

In step S300, the value of the maximum number of processes m is compared with the value of the current number of processes M, and when it is determined that M = m (Yes), the process proceeds to step S302, and M = m is not satisfied. (No), the process proceeds to step S304.
In step S302, a classification impossible process is performed, and the paper dust / dry classification process is terminated.
In step S304, “1” is added to the value of the current processing count M, and the process proceeds to step S276.

In this embodiment, the drive circuit 104 corresponds to the drive means, the residual vibration detection unit 106 corresponds to the residual vibration detection means, the discharge abnormality determination process in FIG. 32 corresponds to the discharge abnormality detection means, and FIG. The paper dust / dry separation process corresponds to the separation means.
Further, the bubble recovery process in step S216, the paper dust recovery process in step S294, the drying recovery process in step S298, and the non-separable process in step S302 correspond to the recovery processing means.

In addition, the pulse width measurement process in FIG. 31 corresponds to the pulse width measurement unit, and the processes in steps S252 and S256 correspond to the comparison unit.
A series of determinations determined as (No) in step S252 and (No) in step S256 correspond to the first determination unit.
A series of determinations determined as (No) in step S252 and (Yes) in step S256 correspond to the second determination unit.

Further, the process in step S272 corresponds to the first storage unit, the process in step S290 corresponds to the second storage unit, and the RAM 128 corresponds to the storage unit.
Further, the processing of step S292 and step S296 corresponds to the abnormality determination means.
Next, the operation of the program when it is determined that paper dust is abnormal in the present embodiment will be briefly described with reference to FIG. 18 and FIGS. 29 to 33.

In FIG. 18, the case where paper dust adheres to a certain nozzle and it is determined that paper dust is abnormal is roughly dried. To simplify the description, the detection timing setting value (Shot number) set by the control unit 102 is shown. Is set to n = 3, and the maximum number of times is set to m = 5.
Now, the discharge abnormality detection process shown in FIG. 30 is executed at a predetermined timing, that is, when the printer is turned on by the control unit 102, when a print start command is input, or when a predetermined number of prints are completed during printing.

  First, a nozzle to be detected is selected (step S200), and a drive instruction signal is output to the drive circuit 104 at time t1 (step S202). The drive signal shown in FIG. 18A is output from the drive circuit to the actuator 22, and the drive signal is turned off at time t12. The “H level” pause signal shown in FIG. 18B is sent from the drive circuit 104 to the control unit 102. When output, the process proceeds to a pulse width measurement process (step S206).

At time t2, the drive / detection switching signal shown in FIG. 18C is output to the changeover switch 116 at “H level” (step S230), and switched to the residual vibration detection circuit 118 side. The residual vibration waveform shown in FIG. 18D of the actuator 22 is detected by the residual vibration detection circuit 118, and the residual vibration pulse shown in FIG. 18E is output to the control unit 102.
When this residual vibration pulse becomes “H” level at time t3, the time at time t3 is set to Ts from the timepiece built in the control unit 102. (Step S236)
Thereafter, since the residual vibration pulse becomes “L” level at time t6, the time at time t6 is set to Te (step S240), the value of (Te−Ts) is set to the pulse width measurement value T, and the RAM 128 is set. (Step S242), the drive / detection switching signal is set to “L level”, and is output to the changeover switch 116 (step S244).

Next, the process proceeds to a discharge abnormality determination process (step S208), and the values of the normal determination flag, the bubble determination flag, and the classification determination flag are reset to “0” (step S250).
Then, the value of the pulse width measurement value T held in the RAM 128 is compared with the upper limit value TR + α of the normal discharge reference value stored in the ROM 126 (step S252). As shown in FIG. 18F, since the pulse width measurement value T at time t6 exceeds TR + α, it is determined that T> TR + α and “1” is set in the classification determination flag ( Step S254), the data is held in the RAM 128, and the process proceeds to Step S210.

Here, since the normal determination flag is “0”, it is determined that it is not normal (step 210), and since the bubble determination flag is also “0”, it is determined that it is not normal (step S214), and in the paper dust / dry separation process of step S218. Transition.
In the paper dust / dry separation process, first, the shot number n is set to “3”, and the maximum processing number m is set to “5” (step 270). The pulse width measurement value T measured in the pulse width measurement process and held in the RAM 128 is set. Is set to T0 as an initial measurement value (step S272), and “1” is set to the processing count M.

Next, the Shot number S is reset to “0” (step S276).
Next, the drive instruction signal is output a number of times set to the number of shots. First, “1” is added to the Shot number S (step S278), the value of the Shot number S becomes “1”, and a drive instruction signal is output to the drive circuit 104 at time t7 (step S280). Is “1” (step S282), after waiting for a predetermined time (step S284), the process returns to step S278.

At time t10 and time t11, the drive instruction signal is output to the drive circuit 104 (step S280). Since the value of the number of shots S becomes “3”, the output of the drive instruction signal is terminated.
At time t12, as shown in FIG. 18B, the pause signal becomes “H level”, the process proceeds to the pulse width measurement process (step S288), and the pulse width measurement measured in the pulse width measurement process and held in the RAM 128 is performed. The value T is sequentially set to Tn as a measured value (step S290). Since the pulse width measurement value T1 at time t13 is equal to the initial measurement value T0, it is determined that there is no paper dust abnormality (step S292), further, it is determined that there is no drying abnormality (step S296), and the process returns to step S276.

Similarly, since the drive instruction signal is output three times and the pause signal becomes “H” level at time t14 (step S286), the process proceeds to the pulse width measurement process (step S288), and is measured by the pulse width measurement process. Then, the value of the pulse width measurement value T held in the RAM 128 is sequentially set to Tn as the measurement value (step S290).
The pulse width measurement value T2 at time t15 exceeds the initial measurement value T0, and it is determined that paper dust is abnormal (step S292), and paper dust recovery processing is performed (step S294).

As described above, paper dust abnormality is determined based on the pulse width of the residual vibration waveform, and paper dust abnormality processing is performed.
If it is determined that there is an abnormality in drying, as shown in FIG. 19, since the pulse width measurement value T2 at time t15 is less than the initial measurement value T0, it is determined that there is an abnormality in drying (step S296), and the drying recovery process is performed. (Step S298).

When it is determined to be normal, as shown in FIG. 20, the pulse width measurement value T0 at time t5 is above TR-α (step S256) and below TR + α (step S252). “1” is set (step S260), and it is determined that it is normal (step S210).
When it is determined that the bubble is abnormal, as shown in FIG. 21, since the pulse width measurement value T0 at time t4 is below TR-α (step S256), “1” is set in the bubble determination flag ( In step S258, it is determined that the bubble is abnormal (step S214), and bubble recovery processing (step S216) is performed.

If it is determined that separation is not possible, even if the maximum number of times of processing is executed (step S300), the difference between the initial measurement value T0 and the sequential measurement value Tn is less than the allowable value ΔT. The determination is not made, and a separation impossible process (step S302) is performed.
Next, another configuration example of the ink jet head in the present invention will be described. 25 to 28 are cross-sectional views each showing an outline of another configuration example of the inkjet head 20. The following description will be made based on these drawings. However, the description will focus on the points different from the above-described embodiment, and the description of the same matters will be omitted.

  In the ink jet head 20 </ b> A shown in FIG. 25, the vibration plate 21 vibrates by driving the piezoelectric element 200, and ink (liquid) in the cavity 23 is ejected from the nozzle 24. A stainless steel metal substrate 204 is bonded to a stainless steel nozzle substrate 26 in which a nozzle (hole) 24 is formed via an adhesive film 205, and a similar stainless steel metal substrate is further formed thereon. 204 is joined via an adhesive film 205. Further, a communication port forming substrate 206 and a cavity substrate 207 are sequentially bonded thereon.

  The nozzle substrate 26, the metal substrate 204, the adhesive film 205, the communication port forming substrate 206, and the cavity substrate 207 are each formed into a predetermined shape (a shape in which a concave portion is formed). A reservoir 28 is formed. The cavity 23 and the reservoir 28 communicate with each other via the ink supply port 210. The reservoir 28 communicates with the ink intake port 29.

  A diaphragm 21 is installed in the opening on the upper surface of the cavity substrate 207, and a piezoelectric element (piezo element) 200 is bonded to the diaphragm 21 via a lower electrode 213. An upper electrode 214 is bonded to the opposite side of the piezoelectric element 200 from the lower electrode 213. The head drive 215 includes a drive circuit that generates a drive voltage waveform. When the drive voltage waveform is applied (supplied) between the upper electrode 214 and the lower electrode 213, the piezoelectric element 200 vibrates and is bonded thereto. The diaphragm 21 vibrates. The volume of the cavity 23 (pressure in the cavity) is changed by the vibration of the vibration plate 21, and the ink (liquid) filled in the cavity 23 is ejected as droplets from the nozzle 24.

The amount of liquid reduced in the cavity 23 due to the discharge of the droplets is replenished by supplying ink from the reservoir 28. Ink is supplied to the reservoir 28 from the ink intake port 29.
26, the ink (liquid) in the cavity 23 is ejected from the nozzles by driving the piezoelectric element 200 as described above. The inkjet head 20 </ b> B has a pair of opposing substrates 220, and a plurality of piezoelectric elements 200 are intermittently installed between the substrates 220 at a predetermined interval.

A cavity 23 is formed between adjacent piezoelectric elements 200. A plate (not shown) is provided in front of the cavity 23 in FIG. 26, and a nozzle substrate 26 is provided in the rear. A nozzle (hole) 24 is formed at a position corresponding to each cavity 23 of the nozzle substrate 26. .
A pair of electrodes 224 are respectively provided on one surface and the other surface of each piezoelectric element 200. That is, four electrodes 224 are bonded to one piezoelectric element 200. By applying a predetermined drive voltage waveform between predetermined electrodes among these electrodes 224, the piezoelectric element 200 is deformed and vibrated in the shear mode (indicated by an arrow in FIG. 26), and the volume of the cavity 23 (shown by an arrow in FIG. 26) The pressure in the cavity) changes, and the ink (liquid) filled in the cavity 23 is ejected as droplets from the nozzle 24. That is, in the inkjet head 20B, the piezoelectric element 200 itself functions as a diaphragm.

  Similarly to the above, the ink jet head 20 </ b> C shown in FIG. 27 ejects ink (liquid) in the cavity 23 from the nozzle 24 by driving the piezoelectric element 200. The inkjet head 20 </ b> C includes a nozzle substrate 26 on which nozzles 24 are formed, a spacer 232, and a piezoelectric element 200. The piezoelectric element 200 is installed at a predetermined distance from the nozzle substrate 26 via a spacer 232, and a cavity 23 is formed in a space surrounded by the nozzle substrate 26, the piezoelectric element 200, and the spacer 232.

  A plurality of electrodes are joined to the upper surface of the piezoelectric element 200 in FIG. That is, the first electrode 234 is joined to the substantially central portion of the piezoelectric element 200, and the second electrodes 235 are joined to both sides thereof. When a predetermined drive voltage waveform is applied between the first electrode 234 and the second electrode 235, the piezoelectric element 200 is deformed and vibrated in the shear mode (indicated by an arrow in FIG. 27). The volume (pressure in the cavity) changes, and the ink (liquid) filled in the cavity 23 is ejected as droplets from the nozzle 24. That is, in the inkjet head 20C, the piezoelectric element 200 itself functions as a diaphragm.

  Similarly to the inkjet head 20D shown in FIG. 28, the ink (liquid) in the cavity 23 is ejected from the nozzle 24 by driving the piezoelectric element 200. The inkjet head 20D includes a nozzle substrate 26 on which nozzles 24 are formed, a cavity substrate 242, a vibration plate 21, and a laminated piezoelectric element 201 formed by laminating a plurality of piezoelectric elements 200.

The cavity substrate 242 is formed into a predetermined shape (a shape in which a recess is formed), whereby the cavity 23 and the reservoir 28 are formed. The cavity 23 and the reservoir 28 communicate with each other via an ink supply port 247. The reservoir 28 communicates with the ink cartridge 3 via the ink supply tube 311.
The lower end in FIG. 28 of the laminated piezoelectric element 201 is joined to the diaphragm 21 through the intermediate layer 244. A plurality of external electrodes 248 and internal electrodes 249 are joined to the laminated piezoelectric element 201. That is, the external electrode 248 is bonded to the outer surface of the laminated piezoelectric element 201, and the internal electrode 249 is installed between the piezoelectric elements 200 constituting the laminated piezoelectric element 201 (or inside each piezoelectric element). ing. In this case, the external electrode 248 and a part of the internal electrode 249 are alternately arranged so as to overlap in the thickness direction of the piezoelectric element 200.

  Then, by applying a drive voltage waveform from the head drive 215 between the external electrode 248 and the internal electrode 249, the laminated piezoelectric element 201 is deformed as indicated by the arrows in FIG. 28 (in the vertical direction in FIG. 28). The diaphragm 21 vibrates by expansion and contraction, and the vibration plate 21 vibrates due to this vibration. The volume of the cavity 23 (pressure in the cavity) is changed by the vibration of the vibration plate 21, and the ink (liquid) filled in the cavity 23 is ejected as droplets from the nozzle 24.

The amount of liquid reduced in the cavity 23 due to the discharge of the droplets is replenished by supplying ink from the reservoir 28. Ink is supplied from the ink cartridge 3 to the reservoir 28 via the ink supply tube 311.
In the ink jet heads 20A to 20D including the piezoelectric elements as described above, droplet ejection is performed based on the vibration plate or the residual vibration of the piezoelectric element functioning as the vibration plate in the same manner as the electrostatic capacity type ink jet head 20 described above. It is possible to detect the abnormality or to identify the cause of the abnormality. The ink jet heads 20B and 20C may be configured such that a vibration plate (vibration plate for residual vibration detection) as a sensor is provided at a position facing the cavity and the residual vibration of the vibration plate is detected. .

  As described above, the droplet ejection apparatus, the droplet ejection head ejection abnormality detection method, and the program according to the present invention perform the operation of ejecting liquid from the droplet ejection head as droplets by driving the electrostatic actuator or the piezoelectric actuator. When the residual vibration of the diaphragm displaced by this actuator was detected, the droplet was ejected normally or not based on the residual vibration pattern of the diaphragm (ejection abnormality) It was decided to detect.

  Further, according to the present invention, when it is determined that the ejection is abnormal, whether or not the cause of the abnormal ejection of the droplet is due to bubble mixing based on the pulse width measurement value measured from the residual vibration waveform of the residual vibration of the diaphragm. Was decided. Further, when it is determined that the cause of the droplet ejection abnormality is other than air bubble mixing, the initial measurement value in the initial state of the pulse width measurement value measured from the residual vibration waveform of the residual vibration of the diaphragm, and the initial state Each time the droplet discharge operation is driven a predetermined number of times, the sequential measurement values of the pulse width measurement value are compared, and if the initial measurement value sequentially increases as the number of droplet discharge operation drives increases, It was determined that the paper dust was abnormal, and on the contrary, when it was small, it was determined that the paper was abnormal.

Therefore, according to the present invention, it is possible to accurately identify the cause of the ejection failure of the droplets of the nozzle and realize the optimum recovery process according to the cause, as compared with the droplet ejection device having the conventional ejection abnormality detection method. . As a result, the recovery process time can be shortened without discharging useless ink for the recovery process.
As described above, the droplet discharge device and the discharge abnormality detection method of the droplet discharge head of the present invention have been described based on the illustrated embodiments. However, the present invention is not limited to this, and the droplet discharge Each unit constituting the head or the droplet discharge device can be replaced with any component that can exhibit the same function. In addition, any other component may be added to the droplet discharge head or the droplet discharge apparatus of the present invention.

  The discharge target liquid (droplet) discharged from the droplet discharge head (in the above-described embodiment, the inkjet head 20) of the droplet discharge apparatus of the present invention is not particularly limited. It can be a liquid containing a material (including a dispersion such as a suspension or an emulsion). That is, an ink containing a filter material for a color filter, a light emitting material for forming an EL light emitting layer in an organic EL (Electro Luminescence) device, a fluorescent material for forming a phosphor on an electrode in an electron emitting device, PDP (Plasma Fluorescent material for forming phosphors in display panel devices, migrating material for forming electrophores in electrophoretic display devices, bank materials for forming banks on the surface of the substrate W, various coating materials, and electrodes Liquid electrode material to form, a particle material to form a spacer for forming a minute cell gap between two substrates, a liquid metal material to form a metal wiring, a lens material to form a microlens, A resist material, a light diffusion material for forming a light diffuser, and the like.

  Further, in the present invention, the droplet receiver to which droplets are to be ejected is not limited to paper such as recording paper, but to other media such as films, woven fabrics, nonwoven fabrics, glass substrates, silicon substrates, etc. It may be a workpiece such as various substrates.

1 is a plan view showing a schematic configuration of an ink jet printer which is a kind of droplet discharge device in an embodiment of the present invention. It is sectional drawing which shows the structure of the head unit of the inkjet printer shown in FIG. It is a top view which shows the structure of the nozzle substrate of the head unit shown in FIG. FIG. 3 is a circuit diagram showing a calculation model of simple vibration assuming residual vibration of the diaphragm shown in FIG. 2. It is a figure which shows an example of the experimental result of the detection waveform of the residual vibration of the diaphragm shown in FIG. 2, and each shows the case of normal and abnormal. It is a figure explaining the detection principle of the residual vibration of the diaphragm which concerns on this invention. It is a graph which shows the change of the residual vibration waveform by the Shot number in the case of dry abnormality. It is the photograph which image | photographed the shot number in the case of paper dust abnormality, and the state of paper dust adhesion, and a cross-sectional schematic diagram. It is a graph which shows the change of the residual vibration waveform by Shot number in the case of paper dust abnormality. It is a block diagram for performing discharge abnormality detection of the present invention. It is a block diagram of the detection timing generation circuit of this invention. It is a circuit diagram of the residual vibration detection circuit of the present invention. It is a block diagram of the pulse width measuring circuit of this invention. It is a timing chart of the pulse width measuring circuit of the present invention. It is a block diagram of the discharge abnormality detection circuit of this invention. It is a block diagram of the classification circuit of this invention. It is a flowchart of the control part of this invention. It is a timing chart in the case of the paper dust abnormality of the classification process of this invention. It is a timing chart in the case of the dry abnormality of the classification process of this invention. It is a timing chart in the case of normal discharge abnormality detection processing of the present invention. It is a timing chart in the case of bubble abnormality of the discharge abnormality detection process of this invention. It is a figure which shows the positional relationship of the wiper shown in FIG. 1, and a head unit. It is a figure which shows the relationship between an inkjet head, a cap, and a pump at the time of a pump suction process. It is the schematic which shows the structure of the tube pump shown in FIG. It is sectional drawing which shows the outline of the other structural example of the inkjet head in this invention. It is sectional drawing which shows the outline of the other structural example of the inkjet head in this invention. It is sectional drawing which shows the outline of the other structural example of the inkjet head in this invention. It is sectional drawing which shows the outline of the other structural example of the inkjet head in this invention. It is a block diagram in case discharge abnormality detection of this invention is performed by a program. It is a flowchart in the case of performing discharge abnormality detection of this invention by a program. It is a flowchart of the pulse width measurement process of this invention. It is a flowchart of the discharge abnormality determination process of this invention. It is a flowchart of the paper dust and dry separation processing of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Inkjet printer, 2 ... Head unit, 3 ... Ink cartridge, 4 ... Carriage, 5 ... Carriage shaft, 6 ... Motor, 20 ... Inkjet head, 13 ... -Wiper, 14 ... Cap, 21 ... Diaphragm, 22 ... Electrostatic actuator, 23 ... Cavity (pressure chamber), 24 ... Nozzle, 26 ... Nozzle substrate, 28 ..Reservoir, 29 ... Ink intake, 30 ... Individual electrode, 31 ... Gap, 32 ... Common electrode, 102 ... Control unit, 104 ... Drive circuit, 106 ... Residual vibration detection unit 110 ... Discharge abnormality detection circuit 112 ... Sorting circuit 114 ... Detection timing generation circuit 116 ... Drive / detection changeover switch 118 ... Residual vibration detection Circuit, 120 ... pulse width measurement circuit

Claims (12)

A diaphragm, an actuator for displacing the diaphragm, a cavity filled with liquid droplets, and an internal pressure increased or decreased by the displacement of the diaphragm, and a liquid communicating with the cavity by increasing or decreasing the pressure inside the cavity A droplet discharge head having a nozzle for discharging the droplet as a droplet;
Drive means for outputting a predetermined drive signal for driving the actuator;
Residual vibration detecting means for detecting residual vibration of the diaphragm;
An abnormal discharge detecting means for detecting an abnormal discharge of a droplet based on the residual vibration pattern of the diaphragm detected by the residual vibration detecting means;
The residual vibration pattern detected by the residual vibration detection means after the drive signal is output a predetermined number of times so that the acoustic impedance around the nozzle is changed by the drive means when the discharge abnormality detection means detects the discharge abnormality. And a separation means for separating a cause of abnormal discharge of the nozzle based on the above. A diaphragm, an actuator for displacing the diaphragm, a cavity filled with liquid droplets, and an internal pressure increased or decreased by the displacement of the diaphragm, and a liquid communicating with the cavity by increasing or decreasing the pressure inside the cavity A droplet discharge head having a nozzle for discharging the droplet as a droplet;
Drive means for outputting a predetermined drive signal for driving the actuator;
Residual vibration detecting means for detecting residual vibration of the diaphragm;
An abnormal discharge detecting means for detecting an abnormal discharge of a droplet based on the residual vibration pattern of the diaphragm detected by the residual vibration detecting means;
The residual vibration pattern detected by the residual vibration detection means after the drive signal is output a predetermined number of times so that the acoustic impedance around the nozzle is changed by the drive means when the discharge abnormality detection means detects the discharge abnormality. Sorting means for sorting the cause of abnormal discharge of the nozzle based on
A droplet discharge apparatus comprising: the discharge abnormality detection unit; and a recovery processing unit that performs a recovery process according to a sorting result of the sorting unit.   The ejection abnormality detection means indicates a pulse width measurement unit that measures the pulse width of the residual vibration waveform of the diaphragm, a measurement value of the pulse width measurement unit, and a normal range of the pulse width in the residual vibration waveform of the diaphragm Comparison means for comparing with a normal discharge reference value, first determination means for determining whether or not a droplet discharged from a nozzle is normal based on a comparison result of the comparison means, and the first determination A second determination unit that determines whether or not the cause of the droplet discharge abnormality from the nozzle is a mixture of bubbles when the droplet discharged from the nozzle is abnormal, 2. The apparatus according to claim 1, wherein when the determination result of the determination means is not a bubble mixture, a classification signal indicating this and a measurement value of the pulse width measurement section are output to the classification means. Or the droplet discharge device of 2.   The second determination unit determines that there is a bubble mixing abnormality when the measurement value of the pulse width measurement unit is less than a normal discharge reference value indicating a lower limit value of a normal range, and the measurement value of the pulse width measurement unit The droplet discharge device according to claim 3, wherein when the value exceeds a normal discharge reference value indicating an upper limit value of a normal range, it is determined that there is an abnormality other than mixing of bubbles.   The classification unit includes a first storage unit that stores an initial measurement value of the pulse width measurement unit in an initial state based on a classification signal input from the ejection abnormality detection unit, and the drive unit after the initial state. A storage unit including a second storage unit that sequentially stores measurement values of the pulse width measurement unit every time it is driven a predetermined number of times, and an initial measurement value stored in the first storage unit of the storage unit, Sequential comparison means for comparing the sequential measurement values stored in the second storage unit, and the comparison result of the comparison means indicates that the initial measurement value is less than the sequential measurement value in accordance with an increase in the number of times of driving of the drive means. 5. The droplet discharge device according to claim 3, further comprising an abnormality determination unit that determines that the paper dust is abnormal when the error occurs.   The classification unit includes a first storage unit that stores an initial measurement value of the pulse width measurement unit in an initial state based on a classification signal input from the ejection abnormality detection unit, and the drive unit after the initial state. A storage unit including a second storage unit that sequentially stores measurement values of the pulse width measurement unit every time it is driven a predetermined number of times, and an initial measurement value stored in the first storage unit of the storage unit, Sequential comparison means for comparing the sequential measurement values stored in the second storage unit, and the comparison result of the comparison means indicates that the initial measurement value becomes the sequential measurement value in accordance with an increase in the number of driving times of the drive means. The liquid droplet ejection apparatus according to claim 3, further comprising an abnormality determination unit that determines that a drying abnormality occurs when the temperature exceeds the upper limit.   The classification unit includes a first storage unit that stores an initial measurement value of the pulse width measurement unit in an initial state based on a classification signal input from the ejection abnormality detection unit, and the drive unit after the initial state. A storage unit including a second storage unit that sequentially stores measurement values of the pulse width measurement unit every time it is driven a predetermined number of times, and an initial measurement value stored in the first storage unit of the storage unit, Sequential comparison means for comparing the sequential measurement values stored in the second storage unit, and the comparison result of the comparison means indicates that the initial measurement value is less than the sequential measurement value in accordance with an increase in the number of times the driving means is driven. It is determined that there is a paper dust abnormality when the value becomes, and when the comparison result of the comparison unit exceeds the sequential measurement value in accordance with an increase in the number of times of driving of the driving unit, it is a drying abnormality. An abnormality judging means for judging The apparatus according to claim 3 or 4, characterized in Rukoto.   The number of times of output of the drive signal by the drive means is set to the number of times that the sorting means can specify whether the cause of abnormal discharge of droplets from the nozzle is due to abnormal drying or abnormal paper dust. The droplet discharge device according to claim 1, wherein the droplet discharge device is a droplet discharge device.   The said classification | category means is provided with the drive stop means which stops the drive of the said drive means and the said residual vibration detection means, when abnormality determination is performed by the said abnormality determination means. The droplet discharge device according to any one of the above.   The separation means is a drive stop means for stopping the drive of the drive means and the residual vibration detection means when an abnormality determination result by the abnormality determination means is not obtained before the number of times of driving reaches a predetermined number of times. The liquid droplet ejection apparatus according to claim 5, further comprising:   The actuator including the diaphragm is driven by a drive signal to vibrate the diaphragm, and after the operation of discharging the liquid in the cavity as a droplet from the nozzle, the residual vibration of the diaphragm is detected and detected. A normal determination step for determining whether or not a droplet ejected from a nozzle is normal from the initial pattern of the residual vibration waveform, and when it is determined abnormal in the normal determination step, the cause of abnormal discharge is a bubble A bubble determination step for determining whether or not it is mixed, and when the determination result of the bubble determination step is not bubble mixing, the operation of discharging the liquid from the nozzle is performed a predetermined number of times, and then the initial residual vibration of the diaphragm and thereafter A separation step is provided to detect whether the droplet discharge abnormality from the nozzle is a drying abnormality or a paper dust abnormality by detecting the residual vibration pattern of the nozzle and comparing the two. Ejection failure detecting method of the droplet discharge head is characterized in that is. The actuator including the diaphragm is driven by a drive signal to vibrate the diaphragm, and after the operation of discharging the liquid in the cavity as a droplet from the nozzle, the residual vibration of the diaphragm is detected and detected. A normal determination step for determining whether or not a droplet discharged from the nozzle is normal from the initial pattern of the residual vibration waveform, and when it is determined abnormal in the normal determination step, the cause of abnormal discharge is a bubble A bubble determination step for determining whether or not it is mixed, and when the determination result of the bubble determination step is not bubble mixing, the operation of discharging the liquid from the nozzle is performed a predetermined number of times, and then the initial residual vibration of the diaphragm and thereafter A separation step of separating whether the droplet discharge abnormality from the nozzle is a drying abnormality or a paper dust abnormality by detecting the residual vibration pattern of
An abnormal discharge detection program for a droplet discharge head, which causes a computer to execute

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