JPH09267488A - Ink jet recording device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect exactly a residual quantity of ink by a method wherein an actuator is displaced by impression of driving voltage to spray ink liquid in an ink chamber, and existence of the ink is detected based on variation of a signal generated by mechanical resonance of the actuator. SOLUTION: A head driving part 19 impresses driving voltage to an electrode 77 of a channel corresponding to a printed data to shear deform a piezoelectric side wall 76 thereby, and a volume of a pressure chamber 75 is decreased. When ink exists in the pressure chamber 75, ink is sprayed from a nozzle 73a of a nozzle plate 73. Thereafter, ink in an ink cartridge is fed to the pressure chamber 75, and the piezoelectric side wall 76 is buffered by the ink. However, when ink does not exist in the pressure chamber 75, though back electromotive force is generated, running out of the ink is detected from a voltage state including this back electromotive force with a judging part 60.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ink jet recording apparatus for spraying ink on a sheet for printing.

[0002]

2. Description of the Related Art In a communication device such as a facsimile device or an information processing device such as a personal computer, data such as characters and figures is usually recorded as visual information.
A recording device capable of printing these data on paper is connected. Various recording methods such as an impact method, a heat-sensitive method, and an ink-jet method are adopted for this recording apparatus. In recent years, an ink-jet method which is excellent in quietness and can print on paper of various materials is adopted. Ink-jet recording apparatuses are frequently used.

In the above ink jet recording apparatus, while the main scanning of the print head is carried out, the ink supplied from the ink cartridge to the print head is sprayed onto the paper to perform printing for one band, and then the paper is printed for one band width. By repeating the printing process of sub-scanning, printing is performed on the entire surface of the paper. Therefore, the ink jet recording apparatus that prints by such an operation is configured so that the ink is contained by loading the foam in the ink cartridge so that the ink supply to the print head can be stabilized and good printing quality can be obtained. At the same time, the presence or absence of ink is detected by an ink detection mechanism so that it is possible to detect ink shortage in advance and prevent defective printing.

That is, the ink shortage detection mechanism of the conventional ink jet recording apparatus is constructed by paying attention to the fact that the ink has conductivity, and it is provided on the bottom of the bottom wall or the side wall of the ink cartridge. It is possible to determine the presence or absence of ink by providing a pair of electrodes in contact with ink and comparing the current value when one electrode is energized with the other with a predetermined value in the printer controller of the recording apparatus main body. It has become.

[0005]

However, in the configuration in which a current is passed through the ink to detect the ink shortage as in the above-mentioned conventional technique, the current deteriorates the ink. Therefore, if the ink is used for a long period of time, the print quality may deteriorate due to the deteriorated ink. There is a problem that

When the ink cartridge is detachably attached to the main body of the recording apparatus so that the ink can be exchanged in the unit of cartridge, the ink cartridge and the main body of the recording apparatus have their electrical contacts in contact with each other. In this way, the printer controller detects the value of the current that is passed between the electrodes. Therefore, with such a configuration, the number of electrical contacts and the number of connecting cables are increased in order to realize detection of ink shortage, and as a result, there is a problem that the head unit becomes larger and the cost increases.

Therefore, according to the present invention, in order to solve the above-mentioned problems, it is possible to prevent deterioration of ink due to energization, to accurately detect the remaining amount of ink, and to simplify the structure and reduce the cost. It is intended to provide an ink jet recording apparatus that can be realized.

[0008]

In order to solve the above-mentioned problems, the invention of claim 1 has an ink chamber filled with ink and an actuator composed of a piezoelectric element member, and the actuator is formed by applying a drive voltage. The presence or absence of ink is detected based on the change in the signal generated by the mechanical resonance of the print head and the actuator that causes the ink droplets to be ejected onto the recording medium by displacing the ink. And a means for detecting ink shortage. As a result, the presence or absence of ink is detected based on the state of mechanical resonance of the actuator of the print head, so there is no need to install electrodes in the ink cartridge or the like as in the past, and the ink is not energized. Therefore, it is possible to prevent the deterioration of the ink due to the energization. Further, as described above, it is not necessary to install an electrode in the ink cartridge, and the ink is detected by the print head and the ink depletion detection means. There is no need to install a new cable or connection cable. Therefore, it is possible to reduce the size of the head unit and reduce the cost. Further, for example, in the case of an ink jet recording apparatus in which ink is replenished by exchanging the ink cartridge, accurate detection of the remaining amount is conventionally required without paying attention to the connection state with the electric contact or the connection cable connected to the electrode when the ink cartridge is exchanged. Although not done, in the configuration of the present invention, since the electrodes and the electrical contacts are not provided as described above, the handling of the ink cartridge at the time of replacement can be facilitated.

According to a second aspect of the present invention, there is provided the ink jet recording apparatus according to the first aspect, wherein the ink depletion detecting means monitors a signal generated by mechanical resonance of the actuator generated when the print head is driven. It is characterized by being. As a result, ink shortage is detected by monitoring a signal generated by mechanical resonance of the actuator when the print head is driven during a printing operation or a maintenance operation such as flushing. Therefore, it is not necessary to install a special mechanism that causes mechanical resonance in the actuator or a signal input circuit that inputs a special signal to the actuator in order to detect the ink exhaustion, and the device configuration can be simplified. At the same time, since the ink shortage is detected when the print head is driven, it is possible to detect the ink shortage before the misprint or the like due to the ink shortage occurs, and prevent these problems.

According to a third aspect of the present invention, there is provided the ink jet recording apparatus according to the first aspect, wherein the ink depletion detecting means detects the presence / absence of ink based on a change in amplitude of a counter electromotive voltage generated by mechanical resonance of the actuator. The feature is that it detects As a result, it becomes possible to monitor the amplitude change of the back electromotive voltage using a simple circuit using a comparator such as a comparator, and it is possible to easily realize the ink shortage detection means and to reliably discharge the ink. Can be detected.

According to a fourth aspect of the present invention, in the ink jet recording apparatus according to the first aspect, the ink shortage detecting means detects ink based on a change in a natural resonance frequency of a signal generated by mechanical resonance of the actuator. The feature is that the presence or absence is detected. This allows
At the natural resonance frequency, the signal generated by the mechanical resonance of the actuator is output at a large level (amplitude). The natural resonance frequency differs depending on the presence or absence of ink. Therefore, if the signal is detected by focusing on the natural resonance frequency, it is possible to highly reliably detect the ink exhaustion. Furthermore, for example, when a detection point is set at the resonance frequency of the signal generated by the mechanical resonance of the actuator when ink runs out, and a detection mechanism that can detect only the output level at that time is adopted, reliable ink runout detection can be performed. realizable. Also, as mentioned above,
Since the level of the signal output at the natural resonance frequency is large and the signal can be detected without the need for an output amplifier circuit such as an amplifier, the detection mechanism can have a simple circuit configuration.

According to a fifth aspect of the present invention, there is provided the ink jet recording apparatus according to the fourth aspect, wherein the ink out detection means has a self-excited oscillation circuit connected to the actuator. With this configuration, a circuit configuration in which the ink shortage detection and the self-excited oscillation circuit are integrated is made smaller than a case where the oscillation circuit is separately provided, so that the circuit is small and simple, and the manufacturing cost can be reduced.

According to a sixth aspect of the present invention, there is provided the ink jet recording apparatus according to the first aspect, wherein the actuator forms at least a part of a partition wall forming the ink chamber. This makes it easier for the actuator to be affected by the presence or absence of ink in the ink chamber, so the change in the signal caused by the mechanical resonance of the actuator becomes noticeable, and the accuracy of ink shortage detection can be significantly improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. The inkjet recording apparatus according to the present embodiment is connected to an information processing apparatus 1 such as a personal computer as shown in FIG. The information processing device 1 is used for inputting and instructing data, a processing device main body 2 having a built-in auxiliary storage device such as a magnetic disk device and a central processing unit, a CRT (cathode-ray tube) 3 for displaying data and the like on a screen. It has a keyboard 4 and a mouse 5 and is connected to a printer 7 which is an ink jet recording apparatus via a printer cable 6 of Centronics specification, for example.

As shown in FIG. 6, the processing apparatus main body 2 is equipped with, for example, a window system 8 as an operating system (OS). The window system 8 includes an application 9 such as a document creation program, a font driver 10 for managing fonts, a CRT driver 11 for managing the CRT 3, a keyboard driver 12 for managing the keyboard 4, and a mouse driver 13 for managing the mouse 5. , One or a plurality of applications 9 can be simultaneously executed in cooperation with various functional groups such as the printer driver 14 that manages the printer 7.

The printer driver 14 is capable of forming dot image data when a "print execution" menu is specified for data displayed on the screen of the CRT 3, for example. Dot data (pixel data arranged in a dot matrix in the horizontal and vertical directions) is formed based on the font data of the text to be displayed, and these dot image data are set in the horizontal direction (raster direction) for each raster. )
Further, the interface (I / F) unit 15 sequentially outputs the print data in units of 8 bits.

The print data output in the raster scan format as described above is input to the I / F (interface) unit 16 of the printer 7, which is an ink jet recording apparatus. The printer 7 is an RA in which a printer controller 17 (ink shortage detection means) and various data areas such as a print buffer area are formed.
M18, ROM 36 in which various control programs such as a printing routine and an out-of-ink determination routine are stored, a head drive unit 19, a CR motor drive unit 20, an LF motor drive unit 33, and various processing operations are instructed. Operation panel 4
6 and a determination unit 60 (ink shortage detection unit) that outputs a high-level determination signal when the ink runs out.

The above-mentioned head drive unit 19 is used for the print head 4
4 is connected. As shown in FIG. 1, the print head 44 is provided with a piezoelectric substrate 71 made of piezoelectric ceramics, which is a piezoelectric element, an upper cover 72 attached to the upper surface of the piezoelectric substrate 71, and a front surface of the piezoelectric substrate 71. It has a nozzle plate 73 and a printed circuit board 74 attached to the lower surface of the piezoelectric substrate 71. The piezoelectric substrate 71 alternately has a plurality of piezoelectric side walls 76 (piezoelectric element members) and grooves formed so as to be parallel to each other by a cutting process such as dicing process. These piezoelectric side walls 76 ... And The grooves are formed by attaching the upper cover 72 to the upper surface of the piezoelectric substrate 71, so that the pressure chambers 75 corresponding to the channels are ...
Are formed. A plurality of nozzles 73a are formed on the nozzle plate 73 so as to correspond to the pressure chambers 75, and these nozzles 73a are formed.
a is adapted to pressurize and eject the ink in the pressure chambers 75 when the volume of the pressure chambers 75 decreases. Further, a through hole 78 is formed in the upper cover 72, and the through hole 78 restores the volume of the pressure chamber 75 by communicating the pressure chamber 75 with the inside of the ink cartridge 30 of FIG. 7. The ink in the ink cartridge 30 is supplied to the pressure chambers 75 ... still,
The piezoelectric substrate 71 corresponds to the actuator of the present invention,
The pressure chamber 75 corresponds to the ink chamber of the present invention.

The piezoelectric side wall 76 forming the pressure chamber 75 is polarized in the arrow B direction. Piezoelectric side wall 7
As shown in FIG. 2, electrodes 77 are formed on the upper portions of both side surfaces of the electrode 6, respectively, by plating, for example. As shown in FIG. 1, the electrodes 77 are respectively connected to the electrode terminals 79 ... Formed on the printed board 74 via wires 80. The electrode terminals 79 are connected to the head drive section 19, and the head drive section 19 applies a drive voltage to the electrodes 77 based on the print data to shear (deform) the piezoelectric side walls 76. The volume of the pressure chamber 75 is increased / decreased.

The determination section 60 is connected to a specific electrode terminal 79 formed on the printed board 74 via a signal line. As shown in FIG. 4, the determination unit 60 includes a band-pass filter (B) in which a normal band is set so that only a counter electromotive voltage component due to mechanical resonance of the piezoelectric sidewall 76 is passed.
PF) 61, an amplifier 62 that amplifies the voltage component that has passed through the bandpass filter 61, a rectifier circuit 63 that rectifies the amplified voltage component, and a rectified voltage from the rectifier circuit 63 that is compared with a reference voltage to obtain a rectified voltage. Has a value larger than the reference voltage, the comparator circuit 64 outputs a high-level determination signal.

The judgment signal of the comparator circuit 64 is shown in FIG.
As shown in (4), the data is output to the printer controller 17. The printer controller 17
The RAM 18 and the ROM 36 described above are connected to be accessible. Then, the printer controller 17 executes the program stored in the ROM 36, and the RAM 1
The print operation is performed by executing print data write processing and read processing for the print buffer area of No. 8. In addition to the printing operation, an ink depletion detection routine is interrupted during printing, and ink depletion is detected based on the determination signal from the determination unit 60. The printer controller 17 is also connected to the CR motor drive unit 20 and the LF motor drive unit 33. CR motor drive unit 20 and LF motor drive unit 33
Is connected to the CR motor 22 used for main scanning and the LF motor 34 used for sub scanning, respectively.
The rotation directions and speeds of the motors 22 and 34 are controlled.

The print head 44 controlled by the printer controller 17 is included in the print head mechanism 21 as shown in FIG. Print head mechanism 21
Has a cartridge holding member 31, an ink supply member 37 provided in the cartridge holding member 31, and an ink cartridge 30 detachably provided in the cartridge holding member 31. Then, the ink supply member 37
The print head 44 described above is provided in the front part of the.
The print head 44 and the ink cartridge 30 are detachable via the cartridge holding member 31.

Inside the ink cartridge 30 described above, a foam 35 having open cells to contain ink is formed.
Is loaded. An ink supply port 30a is formed in the lower part of the front wall (left side wall in the figure) of the ink cartridge 30, and the above-described ink supply member 37 is connected to the ink supply port 30a via a seal member 39. It is fitted tightly. The ink supply member 37 is formed with an ink guide path 37a for communicating the print head 44 with the inside of the ink cartridge 30, and the ink guide path 37a transfers the ink of the ink supply member 37 to the entire print head 44. It is designed to feed channels.

The print head mechanism 2 constructed as described above
As shown in FIG. 8, the units 1 are arranged in the main scanning direction X, and are fixed to the carriage 23 so that the ink ejection direction with respect to the paper 25 (recording medium) forms a predetermined angle. The carriage 23 has a guide shaft 2 horizontally provided in the main scanning direction X.
4 is movably supported and is connected to a scanning belt 26 driven by a CR motor 22. The CR motor 22 driving the scanning belt 26 causes the carriage 23 to move along the guide shaft 24 in the main scanning direction. The print head mechanism 21 is moved to the paper 2 by reciprocating in X direction.
The main scanning is performed while keeping the distance from 5 constant.

The sheet 25 facing the print head mechanism 21 is supported by a platen roller 28.
The platen roller 28 is provided parallel to the guide shaft 24, and both ends thereof are rotatably supported. A roller gear 29 is fixed to one end of the platen roller 28. A motor gear of the LF motor 34 is meshed with the roller gear 29 via an intermediate gear 40,
The LF motor 34 includes an intermediate gear 40 and a roller gear 29.
The sheet 25 is moved in the sub-scanning direction Y by rotating the platen roller 28 via the above. The movement of the paper 25 in the sub-scanning direction Y is repeated each time the print head mechanism 21 is main-scanned to print one band.

The platen roller 28 sets a printing operation area for printing on the paper 25. Also,
A retracted position of the print head mechanism 21 when printing is stopped is set on one side of the platen roller 28, and a capping mechanism 51 is provided at this retracted position. The capping mechanism 51 includes a cap member 52 having a fitting portion 52a for fitting the print head 44, and a fitting member for moving and fitting the cap member 52 to the print head 44 when the carriage 23 is moved to the retracted position. The capping member 52 caps the print head 44 at the retracted position to prevent the print head 44 from drying.

On the lower surface of the carriage 23 on which the print head mechanism 21 is mounted, an encoder element (not shown) which is a non-contact sensor such as an optical or magnetic sensor is provided. A timing slit 43 having a large number of slits at equal intervals is provided in parallel with the guide shaft 24 in the detection direction of the encoder element. When the encoder element moves in the main scanning direction together with the carriage 23, The timing slit 43 is detected and output as an encoder signal. And
As shown in FIG. 6, the encoder signal is input to the printer controller 17, and the printer controller 17 executes the position data read processing from the print buffer area based on the encoder signal. It is supposed to do.

In the above arrangement, the printer controller 17 executes the ink shortage detection routine during printing. That is, first, as shown in FIG.
When the printer controller 17 outputs the pulsed print data to the head drive unit 19 so as to eject the ink from the channel of the signal line connected to the determination unit 60, the ink shortage detection routine is executed by interruption. The head drive unit 19 temporarily stores the print data,
When a print timing signal is input from the printer controller 17, a square wave drive voltage is applied to the electrode 77 of the channel corresponding to the print data. As shown in FIG. 3, for example, the pressure chamber 75
When ink is ejected from a, the voltage V is applied to the electrode 77a.
Further, the GND potential is applied to the electrode 77b. Then, an electric field indicated by an arrow C is generated on the piezoelectric side wall, and as a result, the piezoelectric side wall 76 is sheared and deformed, and the volume of the pressure chamber 75 is reduced.

At this time, if ink is present in the pressure chamber 75a, the ink in the pressure chamber 75a is pressurized, so that the nozzle 73a of the nozzle plate 73 arranged in front of the pressure chamber 75 is pressed. Ink will be ejected from. Then, when the application of the drive voltage is completed, the deformed state of the piezoelectric side wall 76 is released and the volume of the pressure chambers 75a ...
Will be supplied. Therefore, the piezoelectric side wall 76 is in a state in which the shock at the time of deformation is always buffered by the ink, so that the generation of the counter electromotive voltage to the electrode 77a due to the physical resonance at the time of deformation is suppressed. There is. As a result, the drive voltage applied from the head drive unit 19 to the electrode 77a is in a voltage state that does not include the counter electromotive voltage component generated when the piezoelectric sidewall 76 is deformed, as shown in FIG. 9A.

After that, as shown in FIG. 4, when the drive voltage is taken into the judging section 60, the band-pass filter 61 does not pass any other than the set physical resonance frequency width, so that the counter electromotive voltage component is passed. The drive voltage not including the output signal is a constant low-voltage output signal by the bandpass filter 61 (FIG. 9B). When this output signal is amplified (FIG. 9C) and rectified (FIG. 9D) in the amplifier 62 and the rectifier circuit 63, respectively, the value becomes less than the reference voltage.
A low-level judgment signal will be output (see FIG. 9).
(E)).

The above-mentioned judgment signal is taken in by the printer controller 17, as shown in FIG.
Then, the printer controller 17 ends the ink shortage detection routine by detecting the presence of ink based on the determination signal.

On the other hand, when ink is not present in the pressure chamber 75a when the drive voltage is applied to the electrode 77, the shock when the piezoelectric side wall 76 is deformed is not buffered by the ink, so that physical resonance occurs. Will generate a back electromotive force. As a result, the drive voltage applied from the head drive unit 19 to the electrode 77a is in a voltage state including the counter electromotive voltage component generated when the piezoelectric sidewall 76 is deformed, as shown in FIG.

After that, as shown in FIG. 4, when the driving voltage is taken into the judging section 60, it is converted into an output signal consisting of only the back electromotive voltage component in the band pass filter 61 (FIG. 10 (b)). ), Amplifier 62 and rectifier circuit 63
, The back electromotive force components are amplified (see FIG. 10).
(C)) and rectification (FIG. 10 (d)). Since the rectified signal has a voltage value equal to or higher than the reference voltage, the comparator circuit 64 outputs a high level determination signal (FIG. 10 (e)).
This determination signal is fetched by the printer controller 17, as shown in FIG. Then, the printer controller 17 detects the ink shortage based on the determination signal, thereby displaying or notifying that the ink is out on the operation panel 46, and then ends the ink shortage detection routine. .

In this embodiment, the ink shortage detection routine is executed during printing, but prior to printing,
In a state where the carriage 23 is on standby at the retracted position, a pseudo recording signal having a waveform that does not eject ink may be applied to the predetermined electrode 77 of the print head 44 to execute the ink shortage detection routine. Further, according to the above configuration, since it is not necessary to eject ink from the print head, if the drive voltage applied to the electrode 77 is set to a physical resonance frequency for driving, the counter electromotive voltage at a higher level is obtained. Therefore, it is possible to detect the remaining amount of ink more accurately.

In this embodiment, the piezoelectric side wall 76 is provided.
The presence or absence of ink is detected based on the counter electromotive voltage component when the ink is displaced by application of a drive voltage, but the invention is not limited to this. That is, focusing on the existence of the impedance component of the piezoelectric side wall 76 which is the capacitance component sandwiched between the electrodes 77, the presence or absence of ink may be detected based on this impedance component. Specifically, the switch circuits 66 and 66 and the capacitors 68 and 68 are respectively connected in series to the output sides of the driver circuits 65 and 65 for the specific two channels of the head drive unit 19, and the output signals are input to one driver circuit 65. The first inverting circuit 67a for inverting the print timing signal is connected to the switch circuits 66, 66. Then, the input side and the output side of the second inverting circuit 67b are respectively connected between the switch circuits 66, 66 and the capacitors 68, 68,
An oscillation output system may be configured in which the output side of the inverting circuit 67 is externally output via the buffer circuit 69.

According to the above configuration, the frequency characteristic of the piezoelectric element 76 represented by the equivalent circuit of FIG. 12 changes depending on the presence or absence of ink as shown in FIG. 13, and as a result, the natural natural resonance frequency (f ₁ , F ₂ ), the self-excited oscillation output is output from the output terminal of the buffer circuit 69. Therefore, it becomes possible to detect the presence or absence of ink based on the frequency of this oscillation output. Therefore, a large-amplitude oscillation output can be obtained without constructing an electric circuit that handles a delicate voltage, which simplifies the configuration, reduces cost, and enables high-performance residual amount detection. Become. Further, the detection circuit can be built in the head drive unit 19.

[0037]

According to the first aspect of the present invention, there is provided an ink chamber filled with ink and an actuator composed of a piezoelectric element member, and by displacing the actuator by applying a driving voltage, pressure fluctuations in the ink chamber can be achieved. The print head is configured to eject ink droplets onto a recording medium, and an ink shortage detection unit for detecting the presence or absence of ink based on a change in a signal generated by mechanical resonance of the actuator. As a result, the presence or absence of ink is detected based on the state of mechanical resonance of the actuator of the print head, so there is no need to install electrodes in the ink cartridge or the like as in the past, and the ink is not energized. Therefore, it is possible to prevent the deterioration of the ink due to the energization. Further, as described above, it is not necessary to install an electrode in the ink cartridge, and the ink is detected by the print head and the ink depletion detection means. Therefore, an electrical contact connected to the electrode at a portion of the head unit that receives the ink cartridge. There is no need to install a new cable or connection cable. Therefore, it is possible to reduce the size of the head unit and reduce the cost. Further, for example, in the case of an ink jet recording apparatus in which ink is replenished by exchanging the ink cartridge, accurate detection of the remaining amount is conventionally required without paying attention to the connection state with the electric contact or the connection cable connected to the electrode when the ink cartridge is exchanged. Although not done, in the configuration of the present invention, since the electrodes and the electrical contacts are not provided as described above, it is possible to easily handle the ink cartridge at the time of replacement.

According to a second aspect of the invention, there is provided the ink jet recording apparatus according to the first aspect, wherein the ink out detection means monitors a signal generated by mechanical resonance of the actuator generated when the print head is driven. It is a structure that is. As a result, ink shortage is detected by monitoring a signal generated by mechanical resonance of the actuator when the print head is driven during a printing operation or a maintenance operation such as flushing. Therefore, it is not necessary to install a special mechanism that causes mechanical resonance in the actuator or a signal input circuit that inputs a special signal to the actuator in order to detect the ink exhaustion, and the device configuration can be simplified. At the same time, since the ink shortage is detected when the print head is driven, it is possible to detect the ink shortage before the misprint or the like due to the ink shortage occurs and prevent these problems from occurring.

According to a third aspect of the present invention, there is provided the ink jet recording apparatus according to the first aspect, wherein the ink depletion detecting means detects the presence / absence of ink based on a change in amplitude of a counter electromotive voltage generated by mechanical resonance of the actuator. Is a configuration for detecting the. As a result, it becomes possible to monitor the amplitude change of the back electromotive voltage using a simple circuit using a comparator such as a comparator, and it is possible to easily realize the ink shortage detection means and to reliably discharge the ink. There is an effect that the detection of can be performed.

According to a fourth aspect of the present invention, there is provided the ink jet recording apparatus according to the first aspect, wherein the ink-out detecting means detects ink based on a change in a natural resonance frequency of a signal generated by mechanical resonance of the actuator. This is a configuration for detecting the presence or absence. As a result, at the natural resonance frequency, the signal generated by the mechanical resonance of the actuator is output at a large level (amplitude).
The natural resonance frequency differs depending on the presence or absence of ink. Therefore, if the signal is detected by focusing on the natural resonance frequency, it is possible to highly reliably detect the ink exhaustion. Furthermore, for example, when a detection point is set at the resonance frequency of the signal generated by the mechanical resonance of the actuator when ink runs out, and a detection mechanism that can detect only the output level at that time is adopted, reliable ink runout detection can be performed. realizable. Further, as described above, since the level of the signal output at the natural resonance frequency is large and the signal can be detected without the need for an output amplifier circuit such as an amplifier, the detection mechanism can have a simple circuit configuration. Play.

According to a fifth aspect of the present invention, there is provided the ink jet recording apparatus according to the fourth aspect, wherein the ink out detection means has a self-excited oscillation circuit connected to the actuator. As a result, the circuit configuration in which the ink out detection and the self-excited oscillation circuit are integrated is made smaller than the case where the oscillation circuit is separately provided, so that the circuit is small and simple, and the manufacturing cost can be reduced. Play.

According to a sixth aspect of the present invention, there is provided the ink jet recording apparatus according to the first aspect, wherein the actuator forms at least a part of a partition wall forming the ink chamber. As a result, since the actuator is easily affected by the presence or absence of ink in the ink chamber, the change in the signal generated by the mechanical resonance of the actuator becomes remarkable, and the accuracy of ink shortage detection can be significantly improved. Play.

[Brief description of drawings]

FIG. 1 is an explanatory diagram illustrating a connection state between a print head and a determination unit.

FIG. 2 is an explanatory diagram showing a state of a print head before application of a drive voltage.

FIG. 3 is an explanatory diagram showing a state of the print head after application of a drive voltage.

FIG. 4 is a block diagram of a determination unit.

FIG. 5 is a perspective view of an inkjet recording apparatus connected to an information processing apparatus.

FIG. 6 is a block diagram of a control system of the inkjet recording apparatus.

FIG. 7 is a cross-sectional view of an ink cartridge.

FIG. 8 is a perspective view of a main part of the inkjet recording apparatus.

FIG. 9 is an explanatory diagram showing signal states in a determination unit.

FIG. 10 is an explanatory diagram showing signal states in a determination unit.

FIG. 11 is a circuit diagram of a head drive unit.

FIG. 12 is an equivalent circuit diagram of an oscillation output system.

FIG. 13 is a graph showing the relationship between impedance and frequency with and without ink.

[Explanation of symbols]

 17 Printer Controller 19 Head Drive Unit 44 Print Head 60 Judgment Unit 61 Band Pass Filter 62 Amplifier 63 Rectifier Circuit 64 Comparator Circuit 65 Driver Circuit 66 Switch Circuit 67a First Inversion Circuit 67b Second Inversion Circuit 63 Rectification Circuit 68 Capacitor 69 Buffer Circuit 71 Piezoelectric Substrate 72 Top Cover 73 Nozzle Plate 74 Printed Circuit Board 75 Pressure Chamber 76 Piezoelectric Sidewall 77 Electrode 78 Through Port 79 Electrode Terminal

Claims (6)

[Claims] 1. An ink chamber filled with ink, and an actuator composed of a piezoelectric element member, wherein the actuator is displaced by applying a drive voltage,
A print head that applies a pressure fluctuation in the ink chamber and ejects ink droplets onto a recording medium; and an ink out detection unit that detects the presence or absence of ink based on a change in a signal generated by mechanical resonance of the actuator. An inkjet recording apparatus comprising: 2. The ink jet recording apparatus according to claim 1, wherein the ink depletion detection means monitors a signal generated by mechanical resonance of the actuator generated when the print head is driven. 3. The ink jet recording apparatus according to claim 1, wherein the ink depletion detection unit detects the presence or absence of ink based on a change in the amplitude of the counter electromotive voltage generated by mechanical resonance of the actuator. Recording device. 4. The ink shortage detection means is for detecting the presence or absence of ink based on a change in a natural resonance frequency of a signal generated by mechanical resonance of the actuator. Inkjet recording device. 5. The ink jet recording apparatus according to claim 4, wherein the ink depletion detection unit has a self-excited oscillation circuit connected to the actuator. 6. The ink jet recording apparatus according to claim 1, wherein the actuator forms at least a part of a partition wall forming the ink chamber.