JP2013248800A - Inspection device, inspection method and program - Google Patents

Abstract

An object of the present invention is to appropriately obtain a reference range for determining an injection abnormality.
The ejecting unit is based on a result of comparing a plurality of ejecting units that drive a driving element to eject a liquid, an inspection value obtained by driving the driving element, and a reference range for inspection. And a plurality of the inspection values are obtained by driving the drive elements of the plurality of injection units, and the reference range for the inspection is in a region that is greater than or equal to the provisional reference range. An inspection apparatus that is obtained based on the appearance frequency of the plurality of inspection values and the appearance frequency of the plurality of inspection values in an area that is less than or equal to the provisional reference range.
[Selection] Figure 14

Description

  The present invention relates to an inspection apparatus, an inspection method, and a program.

A liquid ejecting apparatus that ejects a liquid such as ink from an ejecting unit such as a nozzle has been developed. In such a liquid ejecting apparatus, an inspection is performed as to whether or not the liquid is appropriately ejected from the ejecting unit.
Patent Document 1 discloses that a nozzle driving actuator is also used as a sensor to detect a nozzle state such as thickening and bubbles from the waveform phase, period, and amplitude.

Japanese Patent No. 4114638

  The inspection of the injection unit as described above is performed based on whether or not the vibration period of the injection unit is within a predetermined range. In order to perform such an inspection, it is necessary to appropriately obtain a reference range in advance. That is, it is desirable to appropriately obtain a reference range for determining an injection abnormality.

  The present invention has been made in view of such circumstances, and an object thereof is to appropriately obtain a reference range for determining an injection abnormality.

The main invention for achieving the above object is:
A plurality of ejecting units that drive the drive elements to eject the liquid;
An inspection unit that inspects the ejection unit based on a result of comparing an inspection value obtained by driving the drive element and a reference range for inspection;
With
A plurality of the inspection values are obtained by driving the driving elements of the plurality of ejection units,
The inspection reference range is obtained based on the appearance frequency of the plurality of inspection values in an area equal to or greater than the provisional reference range and the appearance frequency of the plurality of inspection values in an area equal to or less than the provisional reference range. It is an inspection device.

  Other features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

1 is a block diagram of an overall configuration of a printer 1 according to an embodiment. FIG. 2A is a perspective view of the printer 1, and FIG. 2B is a cross-sectional view of the printer 1. 4 is a diagram illustrating an example of a nozzle arrangement on a temporary surface (nozzle surface) of a head 41. FIG. 4 is a cross-sectional view of the periphery of a nozzle of a head 41. FIG. FIG. 10 is a diagram illustrating another example of a piezoelectric actuator 422. It is a figure which shows the calculation model of the single vibration which assumed the residual vibration of the diaphragm 421. FIG. 3 is a circuit diagram showing an example of a configuration of a residual vibration detection circuit 55. FIG. 6 is a diagram illustrating an example of a relationship between an input and an output of a comparator 57 of the residual vibration detection circuit 55. FIG. It is explanatory drawing of the vibration period regarding a nozzle. 3 is an explanatory diagram illustrating an example of a configuration of a head control unit HC of the head unit 40. FIG. It is explanatory drawing of the timing of each signal. It is a figure explaining the input and output with respect to ASIC60. It is a flowchart of the reference | standard range determination process for a test | inspection in this embodiment. It is explanatory drawing of the method of determining the reference | standard range for a test | inspection. It is explanatory drawing of the random variable in each area | region of a temporary reference | standard range. It is explanatory drawing of the movement of a temporary reference | standard range. It is explanatory drawing of the change of a temporary reference range.

At least the following matters will become clear from the description of the present specification and the accompanying drawings. That is,
A plurality of ejecting units that drive the drive elements to eject the liquid;
An inspection unit that inspects the ejection unit based on a result of comparing an inspection value obtained by driving the drive element and a reference range for inspection;
With
A plurality of the inspection values are obtained by driving the driving elements of the plurality of ejection units,
The inspection reference range is obtained based on the appearance frequency of the plurality of inspection values in an area equal to or greater than the provisional reference range and the appearance frequency of the plurality of inspection values in an area equal to or less than the provisional reference range. It is an inspection device.
By doing in this way, the reference | standard range for a test | inspection can be calculated | required using a temporary reference | standard range. At this time, a reference range for inspection can be statistically obtained based on the appearance frequency of inspection values above the provisional reference range and the appearance frequency of inspection values below the provisional reference range. And the reference | standard range for determining injection abnormality can be calculated | required appropriately.

In this inspection apparatus, the provisional reference range includes a plurality of inspection values that are greater than or equal to the provisional reference range, regions within the provisional reference range, and less than or equal to the provisional reference range. It is desirable to be specified in a range that appears in any region.
By doing in this way, since inspection values in a plurality of injection units appear in any region of the provisional reference half or more and the provisional reference range or less, it is statistically inspected based on the appearance frequency. The reference range can be obtained.

The provisional reference range is preferably narrowed when all of the plurality of inspection values appear in an area within the provisional reference range.
In this way, inspection values within the tentative reference range can appear in areas below the tentative reference range and above the tentative reference range, so statistically based on their appearance frequency. A reference range for inspection can be obtained.

In addition, when the inspection value is input, it is classified into an area that is greater than the provisional reference range, an area that is within the provisional reference range, and an area that is less than or equal to the provisional reference range. It is desirable to provide an arithmetic unit that outputs the information.
In this way, even in a situation where only simple information such as the frequency of appearance of three states above the tentative reference range, within the tentative reference range and below the tentative reference range can be obtained properly, A reference range for inspection can be obtained.

The reference range for inspection is preferably specified based on a distribution center of the plurality of inspection values.
By doing so, a reference range for inspection can be obtained statistically.

In addition, the distribution center includes a first random variable obtained based on an appearance frequency of the plurality of inspection values in a region equal to or greater than the provisional reference range, and the plurality of inspection values in a region equal to or less than the provisional reference range. It is desirable to be obtained based on the ratio of the second random variable obtained from the appearance frequency of.
By doing so, it is possible to statistically obtain a reference range for inspection using a random variable.

In addition, at least the following matters will become clear from the description of the present specification and the accompanying drawings. That is,
A step of obtaining a test value by driving a drive element of the ejection unit;
Comparing the inspection value with a reference range for inspection and inspecting the injection unit;
Including
A plurality of the inspection values are obtained by driving the driving elements of the plurality of ejection units,
The inspection reference range is obtained based on the appearance frequency of the plurality of inspection values in an area equal to or greater than the provisional reference range and the appearance frequency of the plurality of inspection values in an area equal to or less than the provisional reference range. The inspection method.
By doing in this way, the reference | standard range for a test | inspection can be calculated | required using a temporary reference | standard range. At this time, a reference range for inspection can be statistically obtained based on the appearance frequency of inspection values above the provisional reference range and the appearance frequency of inspection values below the provisional reference range. And the reference | standard range for determining injection abnormality can be calculated | required appropriately.

In addition, at least the following matters will become clear from the description of the present specification and the accompanying drawings. That is,
A step of obtaining a test value by driving a drive element of the ejection unit;
Comparing the inspection value with a reference range for inspection and inspecting the injection unit;
A program for causing an inspection apparatus to
A plurality of the inspection values are obtained by driving the driving elements of the plurality of ejection units,
The inspection reference range is obtained based on the appearance frequency of the plurality of inspection values in an area equal to or greater than the provisional reference range and the appearance frequency of the plurality of inspection values in an area equal to or less than the provisional reference range. Is a program.
By doing in this way, the reference | standard range for a test | inspection can be calculated | required using a temporary reference | standard range. At this time, a reference range for inspection can be statistically obtained based on the appearance frequency of inspection values above the provisional reference range and the appearance frequency of inspection values below the provisional reference range. And the reference | standard range for determining injection abnormality can be calculated | required appropriately.

=== Embodiment ===
FIG. 1 is a block diagram of the overall configuration of the printer 1 of the present embodiment. 2A is a perspective view of the printer 1, and FIG. 2B is a cross-sectional view of the printer 1. Hereinafter, a basic configuration of the printer 1 of the present embodiment will be described.

  The printer 1 according to the present embodiment includes a transport unit 20, a carriage unit 30, a head unit 40, a detector group 50, and an ASIC (Application Specific Integrated Circuit) 60 (detector group residual vibration detection circuit 55 and ASIC 60 include an inspection unit. Corresponding to). The printer 1 that has received print data from the computer 110 that is an external device controls each unit (the conveyance unit 20, the carriage unit 30, and the head unit 40) by the ASIC 60. The ASIC 60 controls each unit based on the print data received from the computer 110 and prints an image on paper. The situation in the printer 1 is monitored by the detector group 50, and the detector group 50 outputs the detection result to the ASIC 60. The ASIC 60 controls each unit based on the detection result output from the detector group 50.

  The transport unit 20 is for transporting a medium (for example, paper S) in a first direction (hereinafter referred to as a transport direction). The transport unit 20 includes a paper feed roller 21, a transport motor 22 (also referred to as a PF motor), a transport roller 23, a platen 24, and a paper discharge roller 25. The paper feed roller 21 is a roller for feeding the paper S inserted into the paper insertion slot into the printer. The transport roller 23 is a roller that transports the paper S fed by the paper feed roller 21 to a printable region, and is driven by the transport motor 22. The platen 24 supports the paper S being printed. The paper discharge roller 25 is a roller for discharging the paper S to the outside of the printer, and is provided on the downstream side in the transport direction with respect to the printable area.

  The carriage unit 30 is for moving (also referred to as “scanning”) the head in a second direction (hereinafter referred to as a moving direction). The carriage unit 30 includes a carriage 31 and a carriage motor 32 (also referred to as a CR motor). The carriage 31 can reciprocate in the moving direction and is driven by a carriage motor 32. Further, the carriage 31 detachably holds an ink cartridge that stores ink.

  The head unit 40 is for ejecting ink onto the paper S. The head unit 40 includes a head 41 having a plurality of nozzles and a head controller HC. Since the head 41 is provided on the carriage 31, when the carriage 31 moves in the movement direction, the head 41 also moves in the movement direction. Then, dot heads (raster lines) along the moving direction are formed on the paper S by intermittently ejecting ink while the head 41 is moving in the moving direction.

The head controller HC is for controlling the driving of the head 41 and the like. The head controller HC selectively drives the piezoelectric actuator corresponding to each nozzle of the head 41 in accordance with the head control signal from the ASIC 60. Thereby, ink is ejected from the nozzles of the head 41.
Details of the head unit 40 will be described later.

  The detector group 50 includes a residual vibration detection circuit 55 for performing nozzle injection inspection (hereinafter, also referred to as nozzle inspection, which corresponds to inspection of an injection unit). Although the details of the residual vibration detection circuit 55 will be described later, it is assumed that the inspection by the ink viscosity variation detection in the ejection unit inspection is included in the ejection unit inspection.

  The ASIC 60 is a control unit for controlling the printer. The ASIC 60 includes an interface (not shown), a CPU, a memory, and a drive signal generation circuit in addition to a circuit for performing a specific function. The interface unit transmits and receives data between the computer 110 which is an external device and the printer 1. The CPU is an arithmetic processing unit for controlling the entire printer, and also executes a program. The memory is for securing an area for storing a program of the CPU, a work area, and the like, and includes a storage element such as a RAM or an EEPROM. The drive signal generation circuit generates a drive signal COM that drives the head 41.

  Further, the ASIC 60 of the present embodiment also performs processing for determining whether each nozzle is normal or abnormal based on the detection result of the residual vibration detection circuit 55.

FIG. 3 is a diagram illustrating an example of the nozzle arrangement on the lower surface (nozzle surface) of the head 41.
In the head 41, a plurality of nozzles are arranged as shown in FIG. The example of FIG. 3 shows an arrangement pattern of nozzles when four colors of ink (Y: yellow, M: magenta, C: cyan, K: black) are used, and full color printing is possible by combining these colors. It becomes possible.

  There are n (for example, 180) nozzles for each color. In the figure, numbers (Y (1) to Y (n)) are assigned to the nozzles of the Y (yellow) nozzle row.

  The head 41 of this embodiment uses a piezoelectric actuator (so-called piezo method), and a piezoelectric actuator is provided for each nozzle.

  FIG. 4 is a cross-sectional view around the nozzles of the head 41. As shown in FIG. 4, the head 41 includes a vibration plate 421, a piezoelectric actuator 422 that displaces the vibration plate 421, and ink inside that is liquid inside, and the internal pressure increases or decreases due to the displacement of the vibration plate 421. A cavity (pressure chamber) 423, and a nozzle 424 that communicates with the cavity 423 and ejects ink as droplets by increasing or decreasing the pressure in the cavity 423. The piezoelectric actuator 422, the cavity 423, and the nozzle 424 correspond to an injection unit. Further, the injection unit can include a diaphragm 421. As will be described later, the ejecting unit is not limited to ejecting ink droplets by the piezoelectric element 427, and may eject ink droplets by a heating element, and may be driven without including the piezoelectric actuator 422. What is necessary is just to include an element.

  More specifically, the head 41 includes a nozzle substrate 425 on which a nozzle 424 is formed, a cavity substrate 426, a vibration plate 421, and a laminated piezoelectric actuator 422 in which a plurality of piezoelectric elements 427 are laminated. . The cavity substrate 426 is formed in a predetermined shape as shown in the figure, whereby a cavity 423 and a reservoir 428 communicating with the cavity 423 are formed. The reservoir 428 is connected to the ink cartridge CT via the ink supply tube 429. The piezoelectric actuator 422 is alternately arranged with comb-shaped first electrodes 431 and second electrodes 432 arranged in opposition to each other and each comb tooth of the electrodes (first electrode 431 and second electrode 432). And a piezoelectric element 427. In addition, the piezoelectric actuator 422 has one end joined to the diaphragm 421 via an intermediate layer 430 as shown in FIG.

  In the piezoelectric actuator 422 having such a configuration, a mode in which the drive signal COM is applied between the first electrode 431 and the second electrode 432 so as to expand and contract vertically as indicated by arrows in FIG. Is used. Therefore, in the piezoelectric actuator 422, when the drive signal COM is applied, the diaphragm 421 is displaced by the expansion and contraction of the piezoelectric actuator 422, the pressure in the cavity 423 is changed, and an ink droplet is ejected from the nozzle 424. It has become so. Specifically, as described later, the volume of the cavity 423 is enlarged to draw ink, and then the volume of the cavity 423 is reduced to eject ink droplets.

  FIG. 5 is a diagram illustrating another example of the piezoelectric actuator 422. In addition, the code | symbol in a figure has diverted the thing of FIG. The piezoelectric actuator shown in FIG. 5 is generally called a unimorph actuator and has a simple structure in which a piezoelectric element 427 is sandwiched between two electrodes (first electrode 431 and second electrode 432). In the case of the configuration of FIG. 5, the piezoelectric element 427 bends in the vertical direction in the drawing when a drive signal is applied. As a result, similarly to the stacked actuator of FIG. 4, the vibration plate 421 is displaced and ejects ink droplets. Also in this case, the volume of the cavity 423 is enlarged to draw ink, and then the volume of the cavity 423 is reduced to eject ink droplets from the nozzle 424.

  In the printer 1 having such a head 41, ink droplets are not ejected from the nozzles 424 (non-ejection) due to causes such as running out of ink, thickening of ink, generation of bubbles, clogging (drying), and the like. ) Ink droplet ejection abnormality (so-called dot dropout phenomenon) may occur. In order to detect such an abnormality, it is necessary to perform a nozzle inspection.

<About nozzle inspection>
When a drive signal COM is applied to the piezoelectric actuator 422 corresponding to each nozzle 424, after the pressure fluctuation at that time, residual vibration (more precisely, free vibration of the vibration plate 421 in FIG. 4) occurs. The state of each nozzle 424 (including the state in the cavity 423) can be detected from this residual vibration state.

  FIG. 6 is a diagram showing a simple vibration calculation model assuming residual vibration of the diaphragm 421. When the drive signal COM (drive pulse) is applied from the drive signal generation circuit 65 to the piezoelectric actuator 422, the piezoelectric actuator 422 expands and contracts according to the voltage of the drive signal COM. The vibration plate 421 bends in accordance with the expansion and contraction of the piezoelectric actuator 422, whereby the volume of the cavity 423 is expanded and then contracted. At this time, a part of the ink filling the cavity 423 is ejected as an ink droplet from the nozzle 424 by the pressure generated in the ink chamber. During the operation of the series of vibration plates 421, the natural vibration determined by the flow path resistance r due to the shape of the ink supply port, ink viscosity, etc., the inertance m due to the ink weight in the flow path, and the compliance c of the vibration plate 421. The diaphragm 421 causes free vibration at a frequency (residual vibration).

A calculation model of the residual vibration of the diaphragm 421 can be expressed by the pressure P, the inertance m, the compliance C, and the flow path resistance r described above. When the step response when the pressure P is applied to the circuit of FIG. 6 is calculated for the volume velocity u, the following equation is obtained.

<Residual vibration detection circuit>
FIG. 7 is a circuit diagram showing an example of the configuration of the residual vibration detection circuit 55. The residual vibration detection circuit 55 of this embodiment is provided in common for each nozzle of the head 41.

  The residual vibration detection circuit 55 of the present embodiment detects that the pressure change in the cavity 423 is transmitted to the piezoelectric actuator 422. Specifically, the residual vibration detection circuit 55 is based on the mechanical displacement of the piezoelectric actuator 422. A change in the electromotive force (electromotive voltage) generated is detected. This residual vibration detection circuit 55 is configured to open or close the ground end (transistor Q) that grounds or opens the ground end (HGND application side) of the piezoelectric actuator 422 and the drive terminal COM after applying the drive signal COM pulse to the piezoelectric actuator 422. Thus, an AC amplifier 56 that amplifies the AC component of the residual vibration generated by this, and a comparator (comparator) 57 that compares the amplified residual vibration VaOUT and the reference voltage Vref are configured. Among these, the AC amplifier 56 includes a capacitor C that removes a DC component, and an arithmetic unit AMP that inverts and amplifies at a gain determined by the resistors R1 and R2 with the potential of the reference voltage Vref as a reference. The resistor R3 is provided to suppress a rapid voltage change when the transistor Q is switched on and off.

  With the above configuration, when the gate voltage (gate signal DSEL) of the transistor Q in the residual vibration detection circuit 55 becomes high level (hereinafter also referred to as H level), the transistor Q is turned on, and the ground end of the piezoelectric actuator 422 is grounded. Then, the drive signal COM is supplied to the piezoelectric actuator 422. On the contrary, when the gate voltage (gate signal DSEL) of the transistor Q in each residual vibration detection circuit 55 becomes low level (hereinafter also referred to as L level), the transistor Q is turned off, and the electromotive force of the piezoelectric actuator 422 becomes residual vibration. It is taken out by the detection circuit 55. Then, residual vibration is detected by the residual vibration detection circuit 55, and the detection result is output as a pulse POUT. In addition, the code | symbol HGND in a figure is a signal line (grounding line) to the ground end of the piezoelectric actuator 422.

  Here, the pressure change in the cavity is detected via the piezoelectric actuator 422, but a separate element for detecting vibration may be provided for each nozzle of the head 41. In this case, the element for detecting vibration and the ASIC 60 correspond to the inspection unit.

  FIG. 8 is a diagram illustrating an example of the relationship between the input and output of the comparator 57 of the residual vibration detection circuit 55. The reference voltage Vref is applied to the non-inverting input terminal (+ terminal) of the comparator 57, and the residual vibration VaOUT is applied to the inverting input terminal (−terminal). The comparator 57 outputs an H level if the voltage (Vref) at the + terminal is larger than the voltage (VaOUT) at the − terminal, and becomes L when the voltage (Vref) at the + terminal is smaller than the voltage (VaOUT) at the − terminal. Output level. Therefore, a pulse (COMP output) corresponding to the vibration of the residual vibration VaOUT is output as shown in the figure. In the present embodiment, the nozzle 424 is inspected based on the pulse period (vibration period Tt) of this pulse output (COMP output).

  FIG. 9 is an explanatory diagram of the vibration period related to the nozzle. FIG. 9 shows the vibration period after the piezoelectric actuator 422 is driven. The horizontal axis is time, and the vertical axis is amplitude.

  In FIG. 9, the vibration period Tt of the piezoelectric actuator 422 in a normal nozzle is shown by a solid line. On the other hand, the vibration period Tt when the bubble enters the cavity 423 is indicated by a one-dot chain line. The vibration period Tt when bubbles enter the cavity 423 is shorter than that of a normal one. When bubbles are generated in the ink in the cavity 423, the ink in the cavity 423 is reduced, so that the inertance m mainly decreases. When the inertance m is decreased, the angular velocity ω is increased as shown in the above formula. Therefore, as shown in FIG. 9, the vibration period Tt is shortened.

  In FIG. 9, the vibration period Tt when the ink is thickened is indicated by a broken line. As the ink in the cavity 423 thickens, the flow path resistance r increases. As the flow path resistance r increases, the angular velocity ω decreases as shown in the above formula. Therefore, as shown in FIG. 9, the vibration period Tt becomes long.

  Therefore, a nozzle that is within a predetermined vibration cycle range with respect to the vibration cycle Tt can be considered as a normal nozzle. On the other hand, nozzles that are less than or equal to a predetermined vibration cycle range can be considered as nozzles that are bubbled and do not normally eject, and nozzles that are greater than or equal to the predetermined vibration cycle range are not normally ejected due to thickening. Can be considered.

<About the configuration of the head controller>
FIG. 10 is an explanatory diagram of an example of the configuration of the head controller HC of the head unit 40, and FIG. 11 is an explanatory diagram of the timing of each signal.

  The head controller HC shown in FIG. 10 includes a first shift register 81A, a second shift register 81B, a first latch circuit 82A, a second latch circuit 82B, a decoder 83, a control logic 84, and a switch 86 ( Corresponding to the first switch). Each part excluding the control logic 84 (that is, the first shift register 81A, the second shift register 81B, the first latch circuit 82A, the second latch circuit 82B, the decoder 83, and the switch 86) is provided for each piezoelectric actuator 422. (For each nozzle 424).

  The residual vibration detection circuit 55 of the present embodiment is provided in common for each nozzle 424, and the residual vibration detection circuit 55 includes a signal line (ground line HGND) to the ground end side of each piezoelectric actuator 422. ) Is entered.

  In the present embodiment, the transmission lines in the flexible cable 71 include the transmission lines of the drive signal COM, the latch signal LAT, the channel signal CH, the pixel data SI, the transfer clock SCK, and the ground line HGND. Then, the drive signal COM, the latch signal LAT, the channel signal CH, the pixel data SI, and the transfer clock SCK are transmitted from the ASIC 60 to the head controller HC via the transmission lines of the flexible cable 71. Hereinafter, these signals will be described.

  The latch signal LAT is a signal indicating a repetition period T (a period in which the head 41 moves in a section of one pixel). The latch signal LAT is generated by the ASIC 60 based on the signal of the linear encoder 51, and is input to the control logic 84 and the latch circuit (first latch circuit 82A, second latch circuit 82B).

  The channel signal CH is a signal indicating a section in which the drive pulse included in the drive signal COM is applied to the piezoelectric actuator 422. The channel signal CH is generated by the ASIC 60 based on the signal from the linear encoder 51 and input to the control logic 84.

  The pixel data SI is a signal indicating whether or not dots are formed in each pixel (that is, whether or not ink is ejected from the nozzles 424). In the present embodiment, the pixel data SI also indicates the inspection period of the nozzle 424. This pixel data is composed of 2 bits for each nozzle 424. For example, when the number of nozzles is 64, pixel data SI of 2 bits × 64 is sent from the ASIC 60 every repetition period T. The pixel data SI is input to the first shift register 81A and the second shift register 81B in synchronization with the transfer clock SCK.

  The transfer clock SCK is a signal used when the pixel data SI and the channel signal CH sent from the ASIC 60 are set in the control logic 84 and each shift register (first shift register 81A, second shift register 81B).

  As shown in FIG. 11, the drive signal COM of the present embodiment is provided with four periods of a drive period 1, an inspection period 1, a drive period 2, and an inspection period 2 during the repetition period T. Among these, the driving period 1 includes a waveform 1 (hereinafter also referred to as a waveform for fine vibration) that does not eject ink droplets but gives fine vibration to the ink in the pressure chamber 423 of the head 41. The driving period 2 includes a waveform 2 (hereinafter also referred to as an ejection waveform) that is applied to the piezoelectric actuator 422 when dots are formed (ink ejection). An inspection period 1 and an inspection period 2 indicate periods during which nozzle inspection is performed, and are provided immediately after the driving period 1 and the driving period 2, respectively. Note that the drive signal COM is constant during each inspection period.

  The drive signal COM is input to each switch 86 provided for each piezoelectric actuator 422. The switch 86 performs on / off control as to whether or not to apply the drive signal COM to the piezoelectric actuator 422 based on the pixel data SI. With this on / off control, a part of the drive signal COM can be selectively applied to the piezoelectric actuator 422.

  Next, signals generated by the head controller HC will be described. In the head controller HC, selection signals q0 to q3, a switch control signal SW, and an application signal are generated. The selection signals q0 to q3 are generated by the control logic 64 based on the latch signal LAT and the channel signal CH. Then, the generated selection signals q0 to q3 are respectively input to the decoders 83 provided for each piezoelectric actuator 422.

  As for the switch control signal SW, any one of the selection signals q0 to q3 is selected by the decoder 83 based on the pixel data (2 bits) latched in each latch circuit (first latch circuit 82A, second latch circuit 82B). It is a thing. The switch control signal SW generated by each decoder 83 is input to the corresponding switch 86. The application signal is output from the switch 86 based on the drive signal COM and the switch control signal SW. This application signal is applied to each piezoelectric actuator 422 corresponding to each switch 86.

<Operation of the head controller HC>
The head controller HC performs control for ejecting ink based on the pixel data SI from the ASIC 60. That is, the head controller HC controls the on / off of the switch 86 based on the print data, and selectively applies a necessary portion (period) of the drive signal COM to the piezoelectric actuator 422. In other words, the head controller HC controls the driving of each piezoelectric actuator 422. In the present embodiment, the pixel data SI is composed of 2 bits. The pixel data SI is sent to the head 41 in synchronization with the transfer clock SCK. Further, the upper bit group of the pixel data SI is set in each first shift register 81A, and the lower bit group is set in each second shift register 81B. A first latch circuit 82A is electrically connected to the first shift register 81A, and a second latch circuit 82B is electrically connected to the second shift register 81B.

  When the latch signal LAT from the ASIC 60 becomes H level, each first latch circuit 82A latches the upper bit (SIH) of the corresponding pixel data SI, and each second latch circuit 82B receives the lower bit ( SIL) is latched. Pixel data SI (a set of upper bits and lower bits) latched by the first latch circuit 82A and the second latch circuit 82B is input to the decoder 83, respectively. The decoder 83 selects one of the selection signals q0 to q3 output from the control logic 84 (for example, the selection signal q1) according to the pixel data SI latched by the first latch circuit 82A and the second latch circuit 82B. ) And outputs the selected selection signal as the switch control signal SW. Each switch 86 is turned on / off according to the switch control signal SW, and selectively applies a necessary portion (period) of the drive signal COM to the piezoelectric actuator 422.

  FIG. 12 is a diagram for explaining input and output to the ASIC 60. As shown in FIG. 1 described above, the residual vibration detection circuit 55 of the detector group 50 is connected to the ASIC 60. The ASIC 60 controls various connected units. For the residual vibration detection circuit 55, the vibration period is (1) within the reference range with respect to the vibration period Tt input from the residual vibration detection circuit 55. , (2) It has a function of outputting whether it is below the reference range or (3) above the reference range. Therefore, the ASIC 60 corresponds to a calculation unit.

  The ASIC 60 outputs which of the above three types is input with respect to the input of the residual vibration detection circuit 55 because the nozzle of the vibration period with respect to the input vibration period Tt is (1) no abnormality, (2 This is because it has a function of determining whether (1) bubbles are mixed into the cavity, and (3) the ink in the cavity is thickened.

  Therefore, an upper limit and a lower limit of the reference range can be set in the ASIC 60. These upper and lower limits can be rewritten. The present embodiment can be realized even under a simple configuration in which the ASIC 60 can determine the three states based on the reference range related to the vibration period.

  By the way, when detecting an abnormal injection of a nozzle using such an ASIC 60, it is necessary to appropriately determine a reference range for inspection of an abnormal injection. Further, since the head 41 that ejects ink has a manufacturing error, the reference range is different for each individual. Therefore, it is necessary to determine an appropriate reference range according to each head (or each nozzle row).

  FIG. 13 is a flowchart of the reference range determination process for inspection in the present embodiment. Here, it is assumed that a reference range determination process for inspection is performed for each nozzle row. It is assumed that normal or abnormal nozzles are determined for each nozzle row.

  First, the vibration period Tt of each nozzle is acquired for a nozzle row from the residual vibration detection circuit 55 (S102). The method for obtaining the vibration period Tt is based on the above-described method described with reference to FIGS. Therefore, the description is omitted.

  Next, the appearance frequency of each vibration period Tt within the temporary reference range, below the temporary reference range, and above the temporary reference range is obtained (S104). The provisional reference range (corresponding to the provisional reference range) is a reference range that is provisionally obtained in the previous stage of obtaining the inspection reference range. The upper limit value and the lower limit value of the temporary reference range are set in advance in the ASIC as arbitrary values. Note that the processing when the preset lower limit and upper limit are not appropriate will be described later (FIGS. 16 and 17).

  In calculating the appearance frequency, the vibration period Tt of each nozzle is input to the ASIC 60. Then, it is determined whether the vibration period Tt of each nozzle corresponds to a region within the temporary reference range, a region below the temporary reference range, or a region above the temporary reference range. Then, by counting the number of nozzles corresponding to each region, the vibration period for a certain nozzle row, the region within the provisional reference range, the region below the provisional reference range, and the region above the provisional reference range. The appearance frequency of the area is obtained.

  FIG. 14 is an explanatory diagram of a method for determining a reference range for inspection. FIG. 14 shows a graph in which the horizontal axis represents the vibration period, and the vertical axis represents the frequency of appearance (indicated by “frequency” in the figure). And the appearance frequency of the vibration period Tt about a certain nozzle row is shown as a graph of normal distribution. Note that here, a normal distribution graph is shown assuming that the number of nozzles is sufficiently large, but the frequency of occurrence is not necessarily such.

  Further, FIG. 14 shows a temporary reference range. That is, the provisional lower limit Ltm and provisional upper limit Htm that define the provisional reference range are shown. And the temporary median value Ctm is shown as these centers. Therefore, the width from the provisional lower limit value Ltm to the provisional median value Ctm is the same as the width from the provisional median value Ctm to the provisional upper limit value Htm.

  FIG. 14 also shows a reference range for inspection to be obtained. That is, the lower limit value Lts for inspection and the upper limit value Hts for inspection that define the reference range for inspection are shown. And the center value Cts for a test | inspection is shown as these centers. Therefore, the width Wt from the inspection lower limit value Lts to the inspection median value Cts is the same as the width Wt from the inspection median value Cts to the inspection upper limit value Hts.

  In step S104, the number of appearances not more than the provisional lower limit value Ltm (that is, the provisional reference range or less) and the number of appearances not more than the provisional upper limit value Htm (that is, the provisional reference range or more) are obtained. When these numbers are divided by the number of all nozzles, it can be expressed by a random variable whose total value is “1”.

  FIG. 15 is an explanatory diagram of random variables in the respective regions of the temporary reference range. The random variable obtained as described above becomes Z1 below the provisional lower limit Ltm and becomes Z2 above the provisional upper limit Htm. The random variable in the temporary reference range is 1- (Z1 + Z2).

Next, the distribution center is calculated based on the random variable (appearance frequency) of each region obtained in this way (S106). This distribution center is the median value Cts of the reference range for inspection.
The calculation of the distribution center is obtained by dividing the temporary reference range by the ratio of the random variables. That is, the median value Cts of the reference range for inspection is

Cts = Ltm + (Htm−Ltm) × Z2 / (Z1 + Z2)

It becomes.
In this way, the center of distribution, that is, the median value Cts of the reference range for inspection is obtained.

  Next, reference ranges Lts to Hts for inspection are obtained (S108). The reference range for inspection is obtained by applying ± Wt to the median value Cts of the obtained reference range. That is, the lower limit value Lts of the reference range for inspection is (Cts−Wt). The upper limit value Hts of the reference range for inspection is (Cts + Wt).

  In this way, the reference ranges Lts to Hts for inspection can be obtained. The lower limit value Lts and the upper limit value Hts of the reference range for inspection thus obtained are set in the ASIC 60 shown in FIG. Thus, when the vibration cycle Tt is input from the residual vibration detection circuit 55 to the ASIC 60, it is determined that the nozzles in the inspection reference range Lts to Hts are nozzles that appropriately eject ink. become able to. Further, it is possible to determine that nozzles having a reference range lower limit value Lts or less are nozzles that are mixed with bubbles and cannot be appropriately ejected. Further, it is possible to determine that the nozzles that are equal to or higher than the upper limit value Hts of the reference range are nozzles that cannot be properly ejected due to thickening of ink.

  Here, the inspection reference range is obtained by executing steps S102 to S108 of FIG. 13 only once. However, after step S108 is completed, the process returns to step S104, and steps S104 to S108 are repeated a plurality of times. It is good as well. At this time, the reference range for inspection determined in step S108 is used as a temporary reference range in step S104.

  In step S102, the vibration period Tt for each nozzle is acquired only once, and these vibration periods can be stored in a memory or the like in the ASIC 60. By doing so, it is not necessary to drive the piezo element again to acquire the vibration period again, so that the inspection speed can be improved. On the other hand, these vibration periods may not be stored in a memory or the like, and the vibration periods may be acquired again when the nozzle is actually inspected. In this case, it is possible not to occupy the memory with vibration cycle data.

  FIG. 16 is an explanatory diagram of the movement of the temporary reference range. By the way, when the provisional reference range and the acquired vibration period Tt are completely different values in step S104 of FIG. 13 described above, the acquired vibration period Tt is within the above three regions, that is, within the reference range. There may be a case where all the areas below the reference range and above the reference range are not included. In such a case, the above-mentioned distribution center cannot be calculated.

  For example, as shown in FIG. 16, there is a case where the provisional reference range is too lower than the vibration period group from which the temporary reference range is obtained. In such a case, all the vibration cycles enter beyond the upper limit of the temporary reference range. In such a case, the temporary reference range is gradually moved to the side where the vibration period becomes higher (both the lower limit value Ltm and the upper limit value Htm set in the ASIC 60 are both set slightly larger), and again the ASIC 60 The vibration period Tt is input to to obtain an output. By repeating such an operation, it is possible to find a lower limit value and an upper limit value of the temporary reference range in which the vibration period is included in any region within the temporary reference range, below the reference range, and above the reference range.

  FIG. 17 is an explanatory diagram of changes in the provisional reference range. As shown in FIG. 16 described above, even when the reference range is moved, if the reference range is too wide, the obtained vibration period group may fall within the reference range. Even in such a case, the above-mentioned distribution center cannot be calculated.

  Therefore, as shown in FIG. 17, when all of the obtained vibration periods Tt are within the reference range, the temporary reference range is moved so as to be gradually reduced (the lower limit value set in the ASIC 60). (Ltm is set to a larger value and upper limit value Htm is set to a smaller value), and vibration period Tt is input to ASIC 60 again to obtain an output. By repeating such an operation, it is possible to find a lower limit value and an upper limit value of the temporary reference range in which the vibration period is included in any region within the temporary reference range, below the reference range, and above the reference range.

  In general, it is considered that the majority of nozzles that can normally eject ink among a plurality of nozzles. Therefore, the frequency of occurrence of the vibration cycle of the nozzle that can normally eject ink is the highest, and the frequency of occurrence of the vibration cycle of the nozzle that cannot normally eject ink is low. Therefore, by searching for the center of the vibration period group by the above-described method and determining that the nozzle having the vibration period within the predetermined range from the center value is a nozzle that can normally eject ink, it is possible to properly perform normal operation. A nozzle can be distinguished from an abnormal nozzle.

  In the above embodiment, a so-called serial type printer that discharges ink while moving the head in a direction intersecting the conveyance direction of the paper S has been described as an example. However, a head that is long in the paper width direction of the paper S is fixed to the printer. Needless to say, the above-described method can be performed even for a so-called line head type printer that forms an image by ejecting ink onto the conveyed paper S.

=== Other Embodiments ===
In the above-described embodiment, the printer 1 including the inspection device has been described. However, the present invention is not limited to this, and fluid other than ink (liquid, liquid, in which particles of functional material are dispersed, gel) Such a fluid can also be embodied in a liquid ejection device that ejects or ejects the fluid. For example, color filter manufacturing apparatus, dyeing apparatus, fine processing apparatus, semiconductor manufacturing apparatus, surface processing apparatus, three-dimensional modeling machine, gas vaporizer, organic EL manufacturing apparatus (especially polymer EL manufacturing apparatus), display manufacturing apparatus, film formation You may apply the technique similar to the above-mentioned embodiment to the various apparatuses which applied inkjet technology, such as an apparatus and a DNA chip manufacturing apparatus. These methods and manufacturing methods are also within the scope of application.

  The above-described embodiments are for facilitating the understanding of the present invention, and are not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof.

<About the head>
In the above-described embodiment, ink is ejected using a piezoelectric element. However, the method of ejecting the liquid is not limited to this. For example, other methods such as a method of generating bubbles in the nozzle by heat may be used.

  In this case, in a printer that discharges ink by bubbles generated by generating heat from the heat generating element, the pressure fluctuation may be detected as described above, or the ink in the nozzle is not discharged and the temperature of the heat generating element is increased along with the temperature. An inspection may be performed depending on whether or not the drive voltage changes by utilizing the increase in the resistance value.

1 printer,
20 transport units, 21 paper feed rollers, 22 transport motors,
23 transport roller, 24 platen, 25 discharge roller,
30 Carriage unit, 31 Carriage,
40 head units,
50 detector groups, 55 residual vibration detection circuit,
60 ASIC,
81A first shift register, 81B second shift register,
82A first latch circuit, 82B second latch circuit,
83 Decoder, 84 Control logic, 86 Switch,
421 diaphragm, 422 piezoelectric actuator, 423 cavity,
424 nozzle, 425 nozzle substrate, 426 cavity substrate,
427 Piezoelectric element, 428 reservoir, 429 ink supply tube,
430 Intermediate layer, 431 first electrode, 432 second electrode

Claims (8)

A plurality of ejecting units that drive the drive elements to eject the liquid;
An inspection unit that inspects the ejection unit based on a result of comparing an inspection value obtained by driving the drive element and a reference range for inspection;
With
A plurality of the inspection values are obtained by driving the driving elements of the plurality of ejection units,
The inspection reference range is obtained based on the appearance frequency of the plurality of inspection values in an area equal to or greater than the provisional reference range and the appearance frequency of the plurality of inspection values in an area equal to or less than the provisional reference range. , Inspection equipment.   The provisional reference range is a region where the plurality of inspection values are an area that is greater than or equal to the provisional reference range, an area that is within the provisional reference range, and an area that is less than or equal to the provisional reference range. The inspection apparatus according to claim 1, wherein the inspection apparatus is specified in a range in which also appears.   The inspection apparatus according to claim 2, wherein the temporary reference range is narrowed when all of the plurality of inspection values appear in a region within the temporary reference range.   When the inspection value is input, information on which area is classified into the area above the provisional reference range, the area within the provisional reference range, and the area below the provisional reference range The inspection apparatus according to any one of claims 1 to 3, further comprising an arithmetic unit that outputs the output.   The inspection apparatus according to claim 1, wherein the reference range for inspection is specified based on a distribution center of the plurality of inspection values.   The distribution center includes a first random variable obtained by an appearance frequency of the plurality of inspection values in a region that is equal to or greater than the provisional reference range, and an appearance of the plurality of inspection values in a region that is equal to or less than the provisional reference range. The inspection apparatus according to claim 5, wherein the inspection apparatus is obtained based on a ratio of the second random variable obtained from the frequency. A step of obtaining a test value by driving a drive element of the ejection unit;
Comparing the inspection value with a reference range for inspection and inspecting the injection unit;
Including
A plurality of the inspection values are obtained by driving the driving elements of the plurality of ejection units,
The inspection reference range is obtained based on the appearance frequency of the plurality of inspection values in an area equal to or greater than the provisional reference range and the appearance frequency of the plurality of inspection values in an area equal to or less than the provisional reference range. ,Inspection method. A step of obtaining a test value by driving a drive element of the ejection unit;
Comparing the inspection value with a reference range for inspection and inspecting the injection unit;
A program for causing an inspection apparatus to
A plurality of the inspection values are obtained by driving the driving elements of the plurality of ejection units,
The inspection reference range is obtained based on the appearance frequency of the plurality of inspection values in an area equal to or greater than the provisional reference range and the appearance frequency of the plurality of inspection values in an area equal to or less than the provisional reference range. ,program.

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