JP2019098608A - Liquid discharge device - Google Patents

Abstract

To provide a liquid discharge device capable of reducing application of an unintended voltage to a piezoelectric element due to superposition of disturbance noise and the like.SOLUTION: A liquid discharge device includes: a piezoelectric element being input with a driving signal VBS and a reference voltage signal and having a thickness of at least a part thereof of 1 μm or less; a cavity of which an internal volume changes by displacement of the piezoelectric element; and a nozzle discharging liquid in the cavity according to a change of the internal volume of the cavity. The reference voltage signal is monitored by a first monitoring signal VBSmon.SELECTED DRAWING: Figure 11

Description

  The present invention relates to a liquid discharge device.

  As an ink jet printer (liquid discharge apparatus) which discharges a liquid such as ink to print an image or a document, a printer using a piezoelectric element such as a piezoelectric element is known. The piezoelectric element is provided corresponding to each of the plurality of nozzles in the print head, and each of the plurality of nozzles is driven according to the drive signal to eject a predetermined amount of liquid from the nozzles at a predetermined timing to dot the medium. Form

  In such an inkjet printer, as in Patent Document 1, a control signal (drive signal) corresponding to the amount of ink to be discharged is applied to one electrode of the piezoelectric element, and a holding signal (constant voltage signal) is applied to the other electrode. And discharge the ink by driving the piezoelectric element with the potential difference between the drive signal and the constant voltage signal.

  In the ink jet printer as described in Patent Document 1, the amount of ink ejected from the nozzles depends not only on the drive signal but also on the constant voltage signal. Therefore, it is necessary to accurately apply both the drive signal and the constant voltage signal to the piezoelectric element, and a technology for correcting the drive signal applied to the piezoelectric element by taking into account errors such as external factors in advance. Is used.

Patent No. 6119347 gazette

  However, in the ink jet printer described in Patent Document 1, although the correction of the drive signal is possible if the error of the drive signal is within the allowable range, the allowable range of the error is determined by an irregular factor such as a disturbance noise. If it exceeds, there is a possibility that sufficient correction can not be made.

  Furthermore, in response to the demand for downsizing and densification of a print head provided with a nozzle for discharging a liquid, the demand for downsizing and thinning of a piezoelectric element is increasing, and a piezoelectric formed of a thin film piezoelectric material of 1 μm or less It is desirable to use an element.

  In an ink jet printer using a piezoelectric element composed of such a thin film piezoelectric material, an unintended voltage is generated by superimposing disturbance noise and the like on a drive signal and a constant voltage signal applied to the piezoelectric element. And the piezoelectric element may break down.

  The present invention has been made in view of the problems as described above, and according to some aspects of the present invention, an unintended voltage caused by superposition of disturbance noise is applied to a piezoelectric element. It is possible to provide a liquid discharge device capable of reducing the

  The present invention has been made to solve at least a part of the above-described problems, and can be realized as the following aspects or application examples.

Application Example 1
The liquid discharge apparatus according to this application example receives a drive signal and a reference voltage signal, and a piezoelectric element having a thickness of at least a part of 1 μm or less and a cavitation whose internal volume changes due to displacement of the piezoelectric element. And a nozzle for discharging the liquid in the cavity in response to a change in the internal volume of the cavity, wherein the reference voltage signal is monitored by a first monitoring signal.

  In the liquid discharge apparatus according to this application example, a voltage not intended for the piezoelectric element is monitored by monitoring at least the reference voltage signal of the drive signal for causing the piezoelectric element to discharge and discharging the liquid and the reference voltage signal. Can be detected in advance. This reduces the application of an unintended voltage to the piezoelectric element.

  In addition, in the liquid discharge apparatus according to this application example, since it is possible to detect in advance that an unintended voltage is applied to the piezoelectric element, even if the film thickness of the piezoelectric element is a thin film of 1 μm or less It is possible to reduce the possibility of failure of the piezoelectric element due to an unintended voltage. Therefore, it is possible to miniaturize and increase the density of a print head using a piezoelectric element composed of a thin film piezoelectric material of 1 μm or less.

Application Example 2
The liquid ejection apparatus according to the application example further includes a first power supply generation circuit that generates a first power supply voltage for generating at least one of the drive signal and the reference voltage signal, the first power supply voltage Is monitored by a second monitoring signal, and the supply of the first power supply voltage is stopped based on the second monitoring signal when the value of the first power supply voltage becomes a value different from a predetermined range. Good.

  In the liquid ejection apparatus according to this application example, the drive signal and reference applied to the piezoelectric element are monitored by monitoring the first power supply voltage for generating at least one of the drive signal and the reference voltage signal using the second monitoring signal. It is possible to detect that an unintended voltage is superimposed on the voltage signal in the upstream configuration of the signal generation. This makes it possible to further reduce the superposition of unintended voltages on the drive signal and the reference voltage signal. Therefore, application of an unintended voltage to the piezoelectric element can be further reduced.

  Further, in the liquid discharge device according to the application example, when the value of the first power supply voltage is a value different from the predetermined range, the voltage not intended for the first power supply voltage is stopped by stopping the supply of the first power supply voltage. Can reduce the possibility of failure in the configuration for generating the drive signal and the reference voltage signal.

Application Example 3
In the liquid ejection apparatus according to the application example, the supply of the first power supply voltage may be stopped based on the first monitoring signal when the value of the reference voltage signal becomes a value different from a predetermined range. .

  In the liquid ejection apparatus according to the application example, when the value of the reference voltage signal becomes a value different from the predetermined range, the supply of the first power supply voltage contributing to the generation of the drive signal and the reference voltage signal is stopped. The continuous application of an unintended voltage to the piezoelectric element is reduced. Therefore, by continuously applying an unintended voltage to the piezoelectric element, it is possible to reduce the possibility of the piezoelectric element being broken.

Application Example 4
In the liquid ejection apparatus according to the application example, when the value of the reference voltage signal has a difference of 5% or more from the predetermined range, the supply of the first power supply voltage is stopped based on the first monitoring signal. May be

  In the liquid ejection apparatus according to the application example, when the value of the reference voltage dynamic signal has a difference of 5% or more from the predetermined value, the supply of the first power supply voltage for generating the drive signal and the reference voltage signal is stopped. Thus, continuous application of unintended voltage to the piezoelectric element is reduced. Therefore, by continuously applying an unintended voltage to the piezoelectric element, it is possible to reduce the possibility of the piezoelectric element being broken.

Application Example 5
The liquid ejection apparatus according to the application example includes a detection circuit that detects the reference voltage signal or the first power supply voltage, and the detection circuit includes a first input terminal, a second input terminal, and a first output terminal. The reference voltage signal or the first power supply voltage includes a first comparator, and a second comparator including a third input terminal, a fourth input terminal, and a second output terminal, and the first input terminal includes And a reference voltage is input to the second input terminal, the first comparator compares the first detection voltage with the reference voltage, and A signal indicating a comparison result is output from the output terminal, and the reference voltage signal or the first power supply voltage is divided and the second detection voltage smaller than the first detection voltage is input to the third input terminal. The reference voltage is input to the fourth input terminal. (2) The comparator compares the second detection voltage with the reference voltage, and outputs a signal indicating the comparison result from the second output terminal, and the detection circuit outputs the signal output from the first output terminal And the first monitoring signal may be generated based on the signal output from the second output terminal.

  In the liquid discharge device according to the application example, the first monitoring signal is a reference voltage signal or a result of comparing a first detection voltage obtained by dividing the first power supply voltage with a reference voltage, and a reference voltage. A signal or a second detection voltage smaller than a first detection voltage obtained by dividing the first power supply voltage is generated based on a result of comparison of a reference voltage with a reference voltage. That is, the first monitoring signal uses two comparators for each of the first detection voltage and the second detection voltage which are the reference voltage signal or the two detection voltages obtained by dividing the first power supply voltage. And it is generated based on a common reference voltage. For this reason, it becomes possible to monitor the voltage value of the reference voltage signal with high accuracy, and it becomes possible to improve the detection accuracy for detecting in advance the application of an unintended voltage to the piezoelectric element. Thereby, the application of an unintended voltage to the piezoelectric element can be further reduced.

Application Example 6
In the liquid discharge apparatus according to the application example, a discharge control circuit that receives a discharge control signal and controls application of the drive signal to the piezoelectric element, and a second power supply voltage that operates the discharge control circuit The second power supply voltage may be monitored by a third monitoring signal.

  In the liquid discharge apparatus according to this application example, the second power supply voltage that operates the discharge control circuit that controls the application of the drive signal to the piezoelectric element is monitored by the third monitoring signal, and is not intended for the second power supply voltage. By superimposing the voltage, it is possible to reduce the risk of malfunction of the discharge control circuit.

  Further, in the liquid discharge apparatus according to this application example, since it is possible to reduce the possibility of malfunction of the discharge control circuit, it becomes possible to improve the application accuracy of the drive signal to the piezoelectric element.

Application Example 7
The liquid discharge apparatus according to this application example receives a drive signal and a reference voltage signal, and a piezoelectric element having a thickness of at least a part of 1 μm or less and a cavitation whose internal volume changes due to displacement of the piezoelectric element. A first power supply voltage for generating at least one of the driving signal and the reference voltage signal, a nozzle for discharging the liquid in the cavity according to a change in the internal volume of the cavity, and A first power generation circuit to be generated, a switch circuit positioned between the piezoelectric element and the first power generation circuit, and the reference voltage signal or the first power supply voltage are input through a first resistor. A first comparator including a first input terminal, a second input terminal to which a reference voltage is input, and a first output terminal electrically connected to the switch circuit, the reference voltage signal or the first A third input terminal to which a source voltage is input through the first resistor and the second resistor, a fourth input terminal to which the reference voltage is input, the first output terminal, and the switch circuit. A detection circuit having a second comparator including a connected second output terminal.

  The phrase "electrically connected" means that the first output terminal and the second output terminal may be directly electrically connected to the switch circuit, and the first output terminal and the second output terminal may be connected to the switch circuit. And determines whether to control the switch circuit based on voltage signals output from the first output terminal and the second output terminal, and electrically via a circuit that outputs a signal for controlling the switch circuit. It may be connected. Also, “to be located between” means that the switch circuit should be located on the signal propagation path between the first power supply generation circuit and the piezoelectric element, and physically between the piezoelectric element and the first power supply generation circuit. It does not have to exist.

  In the liquid ejection apparatus according to the application example, the detection circuit detects (monitors) the first power supply voltage generating at least one of the drive signal for displacing the piezoelectric element and ejecting the liquid and the reference voltage signal. . This makes it possible to detect in advance that an unintended voltage is applied to the piezoelectric element, and reduces the unintended application of an unintended voltage to the piezoelectric element.

  Further, in the liquid discharge device according to the application example, the detection circuit monitors the first power supply voltage or the reference voltage signal using two comparators of the first comparator and the second comparator. At this time, the first comparator receives the reference voltage signal or the first power supply voltage via the first resistor to monitor a voltage signal, and the second comparator detects the reference voltage signal or the first voltage. A power supply voltage is input via the first resistor and the second resistor to monitor the voltage signal. That is, the detection circuit monitors whether an unintended voltage is applied to the piezoelectric element by the reference voltage signal or two voltage signals based on the first power supply voltage. Therefore, the detection accuracy of the application of the unintended voltage to the piezoelectric element is improved, and the application of the unintended voltage to the piezoelectric element is reduced.

  In addition, the liquid discharge device according to the application example includes the switch circuit located between the piezoelectric element and the first power supply generation circuit. By including the switch circuit in this manner, when an unintended voltage is applied to the reference voltage signal or the first power supply voltage in the detection circuit, it becomes possible to stop the supply of the first power supply voltage, and the unintended voltage Can be reduced to be continuously applied to the piezoelectric element. Therefore, by continuously applying an unintended voltage to the piezoelectric element, it is possible to reduce the possibility of the piezoelectric element being broken.

  Further, in the liquid discharge apparatus according to this application example, since it is possible to accurately detect in advance an application of an unintended voltage to the piezoelectric element, the film thickness of the piezoelectric element is a thin film of 1 μm or less. Even in this case, it is possible to reduce the possibility of failure of the piezoelectric element due to an unintended voltage. Therefore, it is possible to miniaturize and increase the density of a print head using a piezoelectric element composed of a thin film piezoelectric material of 1 μm or less.

It is a side view which shows the structure of a liquid discharge apparatus. FIG. 6 is a side view showing a peripheral configuration of a printing unit of the liquid discharge device. FIG. 6 is a front view showing a peripheral configuration of a printing unit of the liquid discharge device. FIG. 6 is a perspective view showing a peripheral configuration of a printing unit of the liquid discharge device. It is a perspective view which shows the structure of a discharge head. It is an exploded perspective view showing composition which looked at a discharge head from the lower part of the perpendicular direction. It is a figure which shows the nozzle formation surface in which the nozzle of a discharge head is formed. It is a figure which shows schematic structure of the discharge part containing a nozzle. It is a figure which shows the electric constitution of a liquid discharge apparatus. FIG. 2 is a circuit diagram showing a circuit configuration of a constant voltage monitoring circuit. It is a timing chart which shows monitoring operation of voltage VBS. It is a timing chart which shows the monitoring operation of voltage HVH. It is a timing chart which shows the monitoring operation of voltage VDD.

  Hereinafter, preferred embodiments of the present invention will be described using the drawings. The drawings used are for convenience of illustration. Note that the embodiments described below do not unduly limit the contents of the present invention described in the claims. In addition, not all of the configurations described below are necessarily essential configuration requirements of the present invention.

  Hereinafter, the liquid ejection apparatus according to the present invention will be described by taking an inkjet printer, which is a printing apparatus, as an example.

1. Outline of Liquid Ejection Device The configuration of the liquid ejection device 1 in the present embodiment will be described using FIGS. 1 to 4.

  FIG. 1 is a side view showing the configuration of the liquid ejection device 1. FIG. 2 is a side view showing the peripheral configuration of the printing unit 6 of the liquid discharge device 1. FIG. 3 is a front view showing the peripheral configuration of the printing unit 6 of the liquid ejection device 1. FIG. 4 is a perspective view showing the peripheral configuration of the printing unit 6 of the liquid discharge device 1.

  As shown in FIG. 1, the liquid discharge apparatus 1 includes a delivery unit 3 for delivering the medium M, a support unit 4 for supporting the medium M, a transport unit 5 for transporting the medium M, and a printing unit for printing on the medium M 6 and a control unit 2 that controls these configurations.

  In the following description, the width direction of the liquid ejection device 1 is "scanning direction X", the depth direction of the liquid ejection device 1 is "longitudinal direction Y", and the height direction of the liquid ejection device 1 is "vertical direction Z". The direction in which the medium M is transported is referred to as “transport direction F”. The scanning direction X, the longitudinal direction Y, and the vertical direction Z are directions intersecting each other (perpendicularly), and the transport direction F is a direction intersecting the scanning direction X (perpendicularly).

  The feeding unit 3 has a holding member 31 which rotatably holds a roll R on which the medium M is wound and stacked. The holding member 31 holds different types of media M and roll bodies R having different dimensions in the scanning direction X. In the feeding unit 3, the medium M unwound from the roll body R is fed out toward the support portion 4 by rotating the roll body R in one direction (clockwise direction in FIG. 1).

  The support portion 4 includes a first support portion 41, a second support portion 42, and a third support portion 43 that constitute the transport path of the medium M, from the upstream toward the downstream in the transport direction F. The first support portion 41 guides the medium M delivered from the delivery portion 3 toward the second support portion 42, and the second support portion 42 supports the medium M on which printing is performed, and a third support portion 43 Guides the printed medium M downstream in the transport direction F.

The transport unit 5 includes a transport roller 52 that applies a transport force to the medium M, a driven roller 53 that presses the medium M against the transport roller 52, and a rotation mechanism 51 that drives the transport roller 52. The transport roller 52 and the driven roller 53 are rollers having the scanning direction X as an axial direction.

  The transport roller 52 is disposed below the vertical direction Z of the transport path of the medium M, and the driven roller 53 is disposed above the vertical direction Z of the transport path of the medium M. The rotation mechanism 51 is configured by, for example, a motor and a reduction gear. Then, in the conveyance unit 5, the medium M is conveyed in the conveyance direction F by rotating the conveyance roller 52 in a state where the medium M is nipped by the conveyance roller 52 and the driven roller 53.

  As shown in FIGS. 2 and 3, the printing unit 6 includes a guide member 62 extending along the scanning direction X, a carriage 71 supported by the guide member 62 movably along the scanning direction X, and a carriage 71. A plurality of (five in the present embodiment) discharge heads 40 that are supported and discharge ink (liquid) onto the medium M, and a moving mechanism 61 that moves the carriage 71 in the scanning direction X are provided.

  Furthermore, the printing unit 6 includes a plurality of (five in the present embodiment, see FIG. 4) drive circuit boards 30, a control circuit board 20, and a heat radiation case 81 accommodating the drive circuit boards 30 and the control circuit board 20. And a maintenance unit 91 for performing maintenance on the ejection head 40.

  The carriage 71 is a carriage cover 73 which forms a closed space by a carriage body 72 having an L-shaped cross section when viewed in the scanning direction X, and the carriage body 72 detachably attached to the carriage body 72. And A plurality of discharge heads 40 are supported at the lower part of the carriage 71 in a state of being arranged at equal intervals in the scanning direction X, and the lower end of each discharge head 40 protrudes from the lower surface of the carriage 71 to the outside. On the lower surface of each discharge head 40, a plurality of nozzles 651 from which the ink is discharged is opened in an arrayed state.

  Each ejection head 40 is a so-called inkjet head having pressure generating means (piezoelectric element) for ejecting ink for each nozzle 651, and the opening of each nozzle 651 is supported by the second support portion 42 in a state supported by the carriage 71. It is aimed at. The moving mechanism 61 includes a motor and a reduction gear, and converts the rotational force of the motor into a moving force in the scanning direction X of the carriage 71. Therefore, the carriage 71 reciprocates in the scanning direction X while supporting the plurality of ejection heads 40, the plurality of drive circuit boards 30, and the control circuit board 20 by driving the moving mechanism 61.

  As shown in FIG. 2 and FIG. 4, the front end portion of a rectangular parallelepiped heat dissipation case 81 accommodating each drive circuit board 30 and control circuit board 20 is fixed to the upper end portion of the rear portion of the carriage 71.

  The control circuit board 20 is supported by the carriage 71 via the heat dissipation case 81. A connector 29 is provided on the control circuit board 20.

  The connector 29 is connected to the control unit 2 via a cable 65. That is, the cable 65 electrically connects the control circuit board 20 supported by the carriage 71 reciprocatingly moving in the scanning direction X, and the control unit 2 fixed to the liquid discharge device 1. Therefore, the cable 65 is preferably configured by an FFC (Flexible Flat Cable) that deforms following the reciprocating movement of the carriage 71.

  Further, a plurality of drive circuit boards 30 are provided upright and arranged above the control circuit board 20 in the vertical direction Z. The control circuit board 20 and each drive circuit board 30 are connected by a B to B (Board to Board) connector 83.

The plurality of drive circuit boards 30 are supported by the carriage 71 via the heat dissipation case 81. In detail, the plurality of drive circuit boards 30 are supported by the heat dissipation case 81 in a state of being arranged at equal intervals in the scanning direction X. At this time, the arrangement direction of the plurality of drive circuit boards 30 and the arrangement direction of the plurality of ejection heads 40 are the same. That is, the drive circuit substrate 30 and the ejection head 40 correspond to each other, and a plurality of the ejection circuit 40 are arranged in parallel while being supported by the carriage 71.

  Each drive circuit board 30 is provided with FFC connectors 84 and 85 at its front end. Each of the FFC connectors 84 and 85 is exposed to the carriage 71 from the front surface of the heat dissipation case 81.

  One end of a cable 86 composed of an FFC or the like is detachably connected (retractable) to the FFC connector 84, and one end of a cable 87 composed of an FFC or the like is detachably connected to the FFC connector 85 Be done.

  The connection substrate 74 is connected to the top surface of the discharge head 40 via the B-to-B connector 75. Further, the connection substrate 74 is provided with FFC connectors 76 and 77. The other end of the cable 86 is detachably connected to the FFC connector 76, and the other end of the cable 87 is detachably connected to the FFC connector 77. Therefore, each drive circuit board 30 and each discharge head 40 are electrically connected via the cables 86 and 87 and the connection board 74.

  At this time, the plurality of drive circuit boards 30 are provided in parallel in the heat dissipation case 81, and the plurality of ejection heads 40 are provided in parallel in the carriage main body 72 corresponding to the plurality of drive circuit boards 30. Multiple are provided.

  As shown in FIGS. 2 and 4, the guide member 62 has a guide rail portion 63 extending in the scanning direction X at its lower front surface. The carriage 71 is supported movably in the scanning direction X by a guide rail portion 63 at a carriage support portion 64 provided at the lower part of the rear surface. That is, the carriage support portion 64 is slidably coupled to the guide rail portion 63 in the scanning direction X. That is, the carriage 71 reciprocates along the scanning direction X while being guided by the guide rail portion 63 of the guide member 62 in the carriage support portion 64 by the drive of the moving mechanism 61.

  As shown in FIG. 3, the maintenance unit 91 is provided adjacent to the second support unit 42 in the scanning direction X. The maintenance unit 91 includes a cap 92 for capping the space where each nozzle 651 is opened as a closed space by contacting the discharge head 40. Capping is performed to suppress drying of the ink in each nozzle 651 of the ejection head 40. Capping is an example of maintenance and is not limited to this.

2. Configuration of Discharge Head Here, the configuration of the discharge head 40 in the present embodiment will be described with reference to FIGS. 5 to 7.

  FIG. 5 is a perspective view of the discharge head 40. FIG. As shown in FIG. 5, the discharge head 40 includes a holder 21 and a cover member 27.

  On both sides of the holder 21 in the front-rear direction Y, flange portions 22 are provided integrally with the holder 21. The flange portion 22 is fixed to the carriage body 72 (see FIG. 2) by a screw or the like.

The cover member 27 is provided on the upper side (upper side in FIG. 5) of the holder 21 in the vertical direction Z. The cover member 27 covers an ink flow path (not shown) provided inside for introducing ink to the nozzles 651. Further, above the cover member 27 in the vertical direction Z, an opening 28 is provided through which a BtoB connector 75 (see FIG. 2) connected to the connection substrate 74 (see FIG. 2) is inserted.

  FIG. 6 is an exploded perspective view of the discharge head 40 as viewed from the lower side in the vertical direction Z (the surface on which the nozzles 651 are formed).

  As shown in FIG. 6, the holder 21 of the discharge head 40 is provided with a fixing plate 23, a reinforcing plate 24, and a plurality of (four in the present embodiment) discharge modules 500.

  The holder 21 is made of a conductive material, such as metal, having a strength greater than that of the fixing plate 23. A storage portion 25 for storing the plurality of discharge modules 500 is provided on the surface of the holder 21 at the lower side (upper side in FIG. 6) in the vertical direction Z.

  The accommodation portion 25 has a concave shape that opens downward in the vertical direction Z, and accommodates the plurality of ejection modules 500 fixed by the fixing plate 23. At this time, the opening of the housing portion 25 is sealed by the fixing plate 23. That is, the discharge module 500 is accommodated in the space formed by the accommodation portion 25 and the fixing plate 23. Note that the storage unit 25 may be provided for each discharge module 500, or may be provided continuously across the plurality of discharge modules 500.

  A recess 26 having a concave shape to which the reinforcing plate 24 and the fixing plate 23 are fixed is provided on the surface of the holder 21 on which the housing portion 25 is provided. The reinforcing plate 24 and the fixing plate 23 are sequentially stacked on the bottom of the recess 26.

  The fixing plate 23 is formed of a plate-like member formed of a conductive material such as metal. Further, the fixing plate 23 is provided with an opening 23a penetrating in the vertical direction Z, which exposes the nozzle surface 651a on which the nozzle 651 of each ejection module 500 is provided. The openings 23 a are provided independently for each of the ejection modules 500. The fixing plate 23 is fixed to the side of the nozzle surface 651 a of the ejection module 500 at the periphery of the opening 23 a.

  The reinforcing plate 24 is preferably made of a material having a strength higher than that of the fixing plate 23. In the reinforcing plate 24, an opening 24 a having an inner diameter larger than the outer periphery of the discharge module 500 corresponding to the discharge module 500 joined to the fixing plate 23 is provided to penetrate in the vertical direction Z. The discharge module 500 inserted into the opening 24 a of the reinforcing plate 24 is joined to the fixing plate 23.

  The fixed plate 23 and the holder 21 are mutually pressed by a predetermined pressure and joined while being supported by a support (not shown).

  FIG. 7 is a view showing a nozzle formation surface on which the nozzles 651 of the ejection head 40 are formed.

As shown in FIG. 7, the ejection modules 500 are arranged in a staggered manner on the lower surface of the holder 21 in the vertical direction Z. In the ejection module 500, nozzles 651 for ejecting ink are arranged in parallel along the front-rear direction Y. Further, in the ejection module 500, two rows in the scanning direction X in which the nozzles 651 are arranged in parallel in the front-rear direction Y are provided. The ejection module 500 is provided with 300 or more nozzles 651 per inch in parallel along the scanning direction X, and one ejection module 500 is provided with 600 or more nozzles 651. That is, the discharge head 40 in the present embodiment has 2400 nozzles or more.
1 is provided.

  Further, in the inside of the ejection module 500, a flow path communicating with the nozzle 651 and pressure generation means for causing pressure change in the ink in the flow path are provided.

3. Configuration of Ejection Unit Here, the configuration of the flow path communicating with the nozzle 651 provided in the ejection module 500 and the configuration of the pressure generation unit for causing pressure change in the ink in the flow path will be described with reference to FIG. FIG. 8 is a view showing a schematic configuration corresponding to one of the plurality of ejection units 600 including the plurality of nozzles 651 provided in the ejection module 500. As shown in FIG. As shown in FIG. 8, the discharge module 500 includes a discharge part 600 and a reservoir 641.

  Ink is introduced into the reservoir 641 from an ink cartridge (not shown) via the ink tube and the supply port 661. Such reservoirs 641 are provided for each ink color.

  The discharge unit 600 includes a piezoelectric element 60, a diaphragm 621, a cavity 631, and a nozzle 651. Among these, the diaphragm 621 is displaced by the piezoelectric element 60 provided on the upper surface in FIG. 8, and functions as a diaphragm that enlarges / reduces the internal volume of the cavity 631 filled with the ink. The nozzle 651 is an opening provided in the nozzle plate 632 and in communication with the cavity 631. The inside of the cavity 631 is filled with ink, and the displacement of the piezoelectric element 60 changes the internal volume. The nozzle 651 is in communication with the cavity 631 and discharges the ink in the cavity 631 as droplets in accordance with the change of the internal volume of the cavity 631.

  The piezoelectric element 60 shown in FIG. 8 functions as a pressure generating means, and has a structure in which the piezoelectric body 601 is sandwiched between a pair of electrodes 611 and 612. In the piezoelectric body 601 having this structure, the central portion bends in the vertical direction with respect to both end portions in FIG. 8 together with the electrode 611, the electrode 612, and the diaphragm 621 according to the voltage applied by the electrode 611 and the electrode 612. Well. The piezoelectric body 601 of the piezoelectric element 60 in the present embodiment has a film thickness of 1 μm or less.

  Specifically, a drive voltage Vout (an example of a "drive signal"), which is a voltage signal to be described later, is supplied to an electrode 611 (an example of a "first electrode") of the piezoelectric element 60, and an electrode 612 (a "second electrode"). 1) is supplied with a voltage VBS (an example of a “reference voltage signal”) which is a constant voltage signal described later. The piezoelectric element 60 is configured to bend upward as the potential difference between the drive voltage Vout and the voltage VBS increases, and to deflect downward as the potential difference between the drive voltage Vout and the voltage VBS decreases. That is, the piezoelectric element 60 is displaced by the potential difference between the drive voltage Vout and the voltage VBS.

  Then, when the piezoelectric element 60 bends upward, the internal volume of the cavity 631 is expanded, and the ink is drawn from the reservoir 641. On the other hand, when it is bent downward, the internal volume of the cavity 631 is reduced. Thus, the internal volume of the cavity 631 changes as the piezoelectric element 60 is displaced. Ink is ejected from the nozzle 651 according to the change in the internal volume.

  The piezoelectric element 60 is not limited to the illustrated structure, and may be any type that can deform the piezoelectric element 60 and eject ink such as ink. Further, the piezoelectric element 60 is not limited to bending vibration, and may be configured to use so-called longitudinal vibration.

The piezoelectric element 60 is provided corresponding to the cavity 631 and the nozzle 651 in the ejection module 500.

4. Electrical Configuration of Liquid Ejection Device The electrical configuration of the liquid ejection device 1 in the present embodiment will be described with reference to FIG. FIG. 9 is a block diagram showing the electrical configuration of the liquid ejection device 1. As shown in FIG. 9, the liquid discharge apparatus 1 includes a power supply circuit board 10, a control circuit board 20, a plurality of drive circuit boards 30-1 to 30-n, and a plurality of discharge heads 40-1 to 40-n. . Here, in the liquid discharge apparatus 1 according to the present embodiment, as described above, the control circuit board 20, the plurality of drive circuit boards 30-1 to 30-n, and the plurality of discharge heads 40-1 to 40-n Provided in

  The plurality of drive circuit boards 30-1 to 30-n are all referred to as the drive circuit board 30 when the same configuration is provided and it is not necessary to distinguish them. The plurality of ejection heads 40-1 to 40-n are all referred to as the ejection head 40 if they have the same configuration and need not be distinguished. Further, in the present embodiment, the drive circuit boards 30-i (i = 1 to n) and the ejection heads 40-i are provided correspondingly.

  The power supply circuit board 10 is provided with a high voltage generation circuit 110. Also, the power supply circuit board 10 is electrically connected to the control circuit board 20 via the cable 65.

  The high voltage generation circuit 110 (an example of the “first power supply generation circuit”) is used in the liquid discharge device 1 based on a power supply voltage (for example, AC 100 V which is a commercial power supply) input from the outside of the liquid discharge device 1. The voltage oHVH (for example, DC 42 V) which is a voltage signal is generated and output to the control circuit board 20.

  Further, the power supply circuit board 10 transmits a signal input from a host computer outside the liquid discharge device 1 to the control circuit board 20.

  The power supply circuit board 10 is fixed to the liquid discharge device 1 together with the control unit 2 (see FIG. 1).

  The control circuit board 20 is provided with a control circuit 210 and a switch circuit 220, and is electrically connected to the drive circuit board 30 via the B to B connector 83.

  The control circuit 210 includes an ejection data generation circuit 211 and a drive data generation circuit 212, and is provided on the drive circuit board 30 when various signals such as image data are supplied from the host computer via the power supply circuit board 10. The circuit and various control signals for controlling the discharge head 40 are output.

  Specifically, part of the signal input to the control circuit 210 is input to the ejection data generation circuit 211. Then, the ejection data generation circuit 211 generates plural types of control signals for controlling the ejection of the ink from the ejection unit 600 based on the input signal.

  More specifically, the ejection data generation circuit 211 selects a plurality (n) of print data signals SI1 to SIn for controlling which of the drive voltages COM-A and COM-B described later is selected, and the ejection unit 600. A plurality of (n) latch signals LAT1 to LATn for controlling the cycle of ink ejection are generated and output to the plurality (n) of drive circuit boards 30-1 to 30-n. At this time, the print data signal SIi and the latch signal LATi are input to the drive circuit substrate 30-i. A signal for controlling the discharge input to the drive circuit substrate 30 is referred to as a print data signal SI (an example of a “discharge control signal”) and a latch signal LAT.

  Furthermore, the ejection data generation circuit 211 outputs the clock signal Sck in common to the plurality of drive circuit boards 30-1 to 30-n.

  In addition, part of the signal input to the control circuit 210 is input to the drive data generation circuit 212. The drive data generation circuit 212 generates 2n pieces of drive data dA1 to dAn and dB1 to dBn, which are digital data that is the source of the drive voltage for driving the ejection unit 600, based on the input signal. It outputs to each of the drive circuit boards 30-1 to 30-n. At this time, drive data dAi and dBi are input to the drive circuit board 30-i. The digital data that is the source of the drive voltage input to the drive circuit board 30 is referred to as drive data dA and dB.

  Here, the drive data dA1 to dAn, dB1 to dBn may be digital data obtained by analog / digital converting the waveform (drive waveform) of the drive voltage, and even if it is digital data indicating a difference with respect to the latest drive data. It may be digital data defining the correspondence between the length of each section having a constant slope in the drive waveform and the slope.

  Furthermore, the control circuit 210 includes a monitoring signal determination circuit 213.

  The monitoring signal determination circuit 213 determines the monitoring signal output from each of the high voltage monitoring circuit 331, the constant voltage monitoring circuit 332, and the low voltage monitoring circuit 333 described later, and controls the switch circuit 220 according to the determination result. Output switch control signal Ctrl.

  The switch circuit 220 is located between the high voltage generation circuit 110 and the electrical connection of the piezoelectric element 60 described later. Then, whether switch circuit 220 supplies input voltage oHVH to drive circuit board 30 as voltage HVH (an example of “first power supply voltage”) by switching conduction or non-conduction based on switch control signal Ctrl. Switch whether or not. The voltage oHVH and the voltage HVH are the same voltage signal. As described above, the switch circuit 220 is positioned between the high voltage generation circuit 110 and the piezoelectric element 60 to supply the voltage HVH to the drive circuit substrate 30 that generates various signals applied to the piezoelectric element 60. Can be controlled.

  The drive circuit board 30 is provided with drive circuits 311 and 312, a constant voltage generation circuit 322, a low voltage generation circuit 323, a high voltage monitoring circuit 331, a constant voltage monitoring circuit 332, and a low voltage monitoring circuit 333; And is electrically connected to the discharge head 40.

  The drive data dA and the voltage HVH are input to the drive circuit 311. The drive circuit 311 generates a drive voltage COM-A based on the input drive data dA and the voltage HVH, and outputs the drive voltage COM-A to the discharge head 40.

  The drive data dB and the voltage HVH are input to the drive circuit 312. The drive circuit 312 generates a drive voltage COM-B based on the input drive data dB and the voltage HVH, and outputs the drive voltage COM-B to the discharge head 40.

  Here, the drive circuits 311 and 312 may differ only in the input data and the output drive voltage, and may have the same circuit configuration.

  For example, if the drive data dA and dB are digital data obtained by analog / digital converting the waveforms of the drive voltages COM-A and COM-B, the drive circuits 311 and 312 perform digital / analog conversion on the drive data dA and dB, respectively. After that, class D amplification is performed to a voltage level based on the voltage HVH to generate drive voltages COM-A and COM-B.

  Further, for example, if the drive data dA and dB are digital data defining the correspondence between the length of each section having a constant slope and the slope in the waveform of the drive voltages COM-A and COM-B, respectively, the drive circuit No. 311 and 312 respectively generate an analog signal satisfying the correspondence relationship between the length of each section defined by drive data dA and dB and the slope, and after D level amplification to a voltage level based on voltage HVH, drive voltage COM-A , COM-B.

  The constant voltage generation circuit 322 receives the voltage HVH, steps down the voltage HVH to generate a voltage VBS (for example, DC 6 V) which is a voltage signal of a constant potential, and outputs the voltage VBS to the discharge head 40.

  The voltage HVH is input to the low voltage generation circuit 323 (an example of the “second power supply generation circuit”), and a voltage VDD (eg, DC 3.3 V) which is a voltage signal of a fixed potential is obtained by stepping down the voltage HVH An example of “2 power supply voltage” is generated and output to the discharge head 40.

  It is preferable that the constant voltage generation circuit 322 and the low voltage generation circuit 323 be configured by, for example, a switching regulator, a linear regulator, or the like. This makes it possible to supply stable voltages VBS and VDD with respect to fluctuations in current caused by fluctuations in the number of driving of the discharge section 600 (piezoelectric element 60).

  The high voltage monitoring circuit 331 detects the voltage value of the voltage HVH input to the drive circuit board 30. Then, a monitoring signal HVHmon (an example of a “second monitoring signal”) corresponding to the detection result of the voltage HVH is output to the monitoring signal determination circuit 213.

  The constant voltage monitoring circuit 332 detects the voltage value of the voltage VBS output from the constant voltage generation circuit 322. Then, a monitoring signal VBSmon (an example of a “first monitoring signal”) according to the detection result of the voltage VBS is output to the monitoring signal determination circuit 213.

  The low voltage monitoring circuit 333 detects the voltage value of the voltage VDD output from the low voltage generation circuit 323. Then, a monitoring signal VDDmon (an example of a “third monitoring signal”) corresponding to the detection result of the voltage VDD is output to the monitoring signal determination circuit 213.

  The aforementioned monitoring signal determination circuit 213 determines each of the monitoring signals HVHmon, VBSmon, and VDDmon, and outputs a switch control signal Ctrl according to the determination result.

  The configurations and operations of the high voltage monitoring circuit 331, the constant voltage monitoring circuit 332, and the low voltage monitoring circuit 333 will be described later.

  Further, the drive circuit substrate 30 transfers the print data signal SI, the latch signal LAT, and the clock signal Sck input from the discharge data generation circuit 211 to the discharge head 40.

  Here, as described above, the drive circuit board 30 and the ejection head 40 are electrically connected by the cable 86 and the cable 87. Among them, the cable 86 transfers the drive voltages COM-A and COM-B and the voltages VDD and VBS from the drive circuit substrate 30 to the ejection head 40, and the cable 86 transmits the print data signal SI, the latch signal LAT and the clock signal Sck. Transfer

  As described above, the cable 87 for transferring the print data signal SI, the latch signal LAT and the clock signal Sck, which controls the discharge based on the voltage of several mV, and the drive voltages COM-A and COM-B which are voltage signals of several V or more. By providing the cables 86 for transferring the voltages VDD and VBS, it is possible to reduce interference between the signals of each other.

  The ejection head 40 includes a plurality (m) of ejection modules 500.

  Each of the plurality of ejection modules 500 includes a drive signal selection circuit 510 and a plurality of ejection units 600.

  The drive signal selection circuit 510 (an example of “ejection control circuit”) includes a selection control circuit 520 and a plurality of selection circuits 530. The drive signal selection circuit 510 is formed of, for example, an IC (Integrated Circuit), and operates by being supplied with the voltage VDD.

  The print data signal SI, the latch signal LAT, and the clock signal Sck are input to the selection control circuit 520.

  Selection control circuit 520 is a selection signal for controlling which of drive voltages COM-A and COM-B should be selected (or not selected at all) for each of a plurality of selection circuits 530. Is generated based on the print data signal SI, and is output based on the printing cycle determined by the latch signal LAT.

  The drive voltages COM-A and COM-B generated by the drive circuits 311 and 312 are input to the selection circuits 530, respectively. Then, in accordance with the selection signal output from the selection control circuit 520, one of the drive voltages COM-A and COM-B is selected, and is output to the corresponding discharge unit 600 as the drive voltage Vout. The drive voltage Vout is applied to one end of the piezoelectric element 60 as described above.

  Further, the voltage HVH is input to the selection circuit 530. The selection circuit 530 selects the high-voltage drive voltages COM-A and COM-B amplified based on the voltage HVH in the drive circuits 311 and 312, and outputs the selected drive voltages as the drive voltage Vout. Therefore, it is preferable that the signal used by the selection circuit 530 to control which of the drive voltages COM-A and COM-B is selected is a high voltage signal. In the present embodiment, a high voltage HVH is supplied to the selection circuit 530, and the selection circuit 530 controls which of the drive voltages COM-A and COM-B is selected using the voltage HVH. The selection control of the drive voltages COM-A and COM-B can be performed more reliably.

  As described above, drive signal selection circuit 510 receives print data signal SI, latch signal LAT and clock signal Sck, and selects input drive voltages COM-A and COM-B based on the received signals. The voltage is supplied to the piezoelectric element 60 as the drive voltage Vout. In other words, the drive signal selection circuit 510 controls the supply of the drive voltages COM-A and COM-B to the piezoelectric element 60.

  Each of the plurality of ejection units 600 includes a piezoelectric element 60 and is provided in each of the selection circuits 530 at the other center. The drive voltage Vout output from the selection circuit 530 is applied to one end of the piezoelectric element 60, and the voltage VBS is applied to the other end. Then, the piezoelectric element 60 is displaced by the potential difference between the drive voltage Vout and the voltage VBS, and the ink is ejected from the ejection unit 600 (nozzle 651) based on the displacement.

5. Configuration and Operation of Constant Voltage Monitoring Circuit Here, the configuration of the constant voltage monitoring circuit 332 and the operation of the constant voltage monitoring circuit 332 generating the monitoring signal VBSmon will be described with reference to FIG.

  FIG. 10 is a circuit diagram showing a circuit configuration of the constant voltage monitoring circuit 332. As shown in FIG.

  The constant voltage monitoring circuit 332 (an example of “detection circuit”) includes resistors 351, 352, 353, 354 and comparators 361, 362.

  The voltage VBS is input to one end of the resistor 351, and the other end is connected to one end of the resistor 352. The other end of the resistor 352 is connected to one end of the resistor 353. Further, the other end of the resistor 353 is connected to a reference potential (for example, a ground potential). That is, the resistors 351, 352, 353 are connected in series between the voltage VBS and the reference potential.

  The comparator 361 (an example of “first comparator”) includes a non-inverted input terminal (+) (an example of “first input terminal”) and an inverted input terminal (−) (an example of “second input terminal”) And an output terminal (an example of a "first output terminal").

  The non-inverting input terminal (+) of the comparator 361 is connected to the other end of the resistor 351 (an example of the “first resistor”) and one end of the resistor 352 (an example of the “second resistor”). Therefore, at the non-inversion input terminal (+) of the comparator 361, the voltage value of the voltage VBS is divided by the resistance value of the resistor 351 and the resistance value of the sum of the resistance value of the resistor 352 and the resistance value of the resistor 353. The compressed voltage V1 (an example of the "first detection voltage") is input. In other words, the voltage VBS is input to the non-inverting input terminal (+) of the comparator 361 via the resistor 351. Further, the reference voltage Vref (an example of “reference voltage”) is input to the inverting input terminal (−) of the comparator 361.

  The comparator 362 (an example of “second comparator”) includes a non-inverted input terminal (+) (an example of “fourth input terminal”) and an inverted input terminal (−) (an example of “third input terminal”) And an output terminal (an example of the “second output terminal”), for example, a comparator.

  The reference voltage Vref is input to the non-inverting input terminal (+) of the comparator 362. The inverting input terminal (−) of the comparator 361 is connected to the other end of the resistor 352 and one end of the resistor 353. Therefore, at the inverting input terminal (-) of comparator 362, the voltage value of voltage VBS is divided by the resistance value of the sum of the resistance value of resistor 351 and the resistance value of resistor 352 and the resistance value of resistor 353 A voltage V2 (an example of a "second detection voltage") smaller than the output voltage V1 is input. In other words, the voltage VBS is input to the non-inverted input terminal (+) of the comparator 361 via the resistor 351 and the resistor 352.

  The output terminal of the comparator 361 and the output terminal of the comparator 362 are connected in common, and are output from the constant voltage monitoring circuit 332 as the monitoring signal VBSmon.

  Here, when the voltage input to the non-inverting input terminal (+) is larger than the voltage input to the inverting input terminal (-), the comparators constituting the comparator 361 and the comparator 362 compare The output terminal of the unit 362 becomes high impedance. On the other hand, when the voltage input to the non-inverting input terminal (+) is smaller than the voltage input to the inverting input terminal (-), the comparators constituting the comparator 361 and the comparator 362 are the comparator 361 and the comparator A reference potential voltage signal (L level signal) is output from the output terminal 362.

  The voltage Vdd is input to one end of the resistor 354, and the other end is connected to the output terminal of the comparator 361 and the output terminal of the comparator 362. That is, the resistor 354 functions as a pull-up resistor for stabilizing the output signal of the constant voltage monitoring circuit 332. For example, the voltage VDD may be input as the voltage Vdd.

In the constant voltage monitoring circuit 332 as described above, when the voltage value of the voltage VBS is in the normal voltage range (hereinafter referred to as a normal voltage), the monitoring signal V of the voltage signal of the voltage Vdd (signal of H level)
When BSmon is output and the voltage value of the voltage VBS is different from the normal voltage range (hereinafter referred to as an abnormal voltage), the monitoring signal VBSmon of the voltage signal of the reference potential (L level signal) is output as a comparison result.

  Specifically, when the voltage value of the voltage VBS is a normal voltage, the resistance values of the resistors 351, 352, 353 are set such that the voltage V1 is larger than the reference voltage Vref and the voltage V2 is smaller than the reference voltage Vref. It is done.

  When the voltage V1 is larger than the reference voltage Vref, the voltage (voltage V1) of the non-inverting input terminal (+) of the comparator 361 is larger than the voltage (reference voltage Vref) of the inversion dominant terminal (−). The output terminal of is high impedance. Further, when the voltage V2 is smaller than the reference voltage Vref, the voltage (reference voltage Vref) of the non-inverting input terminal (+) of the comparator 362 is larger than the voltage (voltage V2) of the inversion dominant terminal (-). The output terminal of the unit 362 is high impedance.

  Thus, when the voltage value of the voltage VBS is a normal voltage, both the output terminal of the comparator 361 and the output terminal of the comparator 362 have high impedance. Therefore, the constant voltage monitoring circuit 332 outputs the monitoring signal VBSmon at the H level corresponding to the voltage Vdd input through the resistor 354.

  Further, resistance values of the resistors 351, 352, 353 are set such that the voltage V2 becomes larger than the reference voltage Vref when the voltage value of the voltage VBS is an abnormal voltage larger than the normal voltage.

  When the voltage V2 is larger than the reference voltage Vref, the voltage (reference voltage Vref) of the non-inversion input terminal (+) of the comparator 362 is smaller than the voltage (voltage V2) of the inversion dominant terminal (-). Thus, the comparator 362 outputs an L level signal from the output terminal. In other words, when the voltage V2 is larger than the reference voltage Vref, the comparator 362 outputs an L level signal from the output terminal.

  Thus, when the voltage value of the voltage VBS is an abnormal voltage larger than the normal voltage, the comparator 362 outputs an L level signal from the output terminal. Therefore, the constant voltage monitoring circuit 332 outputs the L level monitoring signal VBSmon corresponding to the reference potential.

  When the voltage value of the voltage VBS rises and the voltage V2 and the reference voltage Vref become equal, the voltage value of the voltage VBS becomes a voltage VHth1 which is the upper limit voltage value of the normal voltage of the voltage VBS.

  The resistance values of the resistors 351, 352, and 353 are set such that the voltage V1 is smaller than the reference voltage Vref when the voltage VBS is an abnormal voltage smaller than the normal voltage range.

  When the voltage V1 is smaller than the reference voltage Vref, the voltage (voltage V1) of the non-inversion input terminal (+) of the comparator 361 becomes smaller than the voltage (reference voltage Vref) of the inversion dominant terminal (−). Therefore, the comparator 361 outputs an L level signal from the output terminal. In other words, when the voltage V1 is smaller than the reference voltage Vref, the comparator 361 outputs an L level signal from the output terminal.

As described above, when the voltage VBS is an abnormal voltage smaller than the normal voltage, the comparator 361 outputs an L level signal from the output terminal. Therefore, the constant voltage monitoring circuit 332 outputs the L level monitoring signal VBSmon corresponding to the reference potential.

  When the voltage value of the voltage VBS decreases and the voltage V1 becomes equal to the reference voltage Vref, the voltage value of the voltage VBS becomes the voltage VLth1, which is the lower limit voltage value of the normal voltage of the voltage VBS.

  As described above, in the constant voltage monitoring circuit 332, when at least one of the comparator 361 and the comparator 362 outputs an L level signal from the output terminal, the voltage value of the voltage VBS is a normal voltage (voltage in a predetermined range) And a signal of L level is output as the monitoring signal VBSmon.

  At this time, in a range (predetermined range) in which the voltage value of voltage VBS set based on resistors 351, 352, 353 is a normal voltage, the voltage value of voltage VBS is ±± of a predetermined value (for example, target voltage value). It is preferably in the range of 5%. In other words, if the voltage VBS has a difference of ± 5% or more from the predetermined value, the constant voltage monitoring circuit 332 determines that the voltage VBS is not the normal voltage, and the L level Output the monitoring signal VBSmon of This makes it possible to further improve the accuracy of monitoring of the voltage VBS.

  The configuration of high voltage monitoring circuit 331 and the operation of generating monitoring signal HVHmon, and the configuration of low voltage monitoring circuit 333 and the operation of generating monitoring signal VDDmon generate the configuration of constant voltage monitoring circuit 332 and monitoring signal VBSmon. The operation is the same as that of the voltage signal to be input and the voltage signal to be output.

  The upper limit voltage value in the normal range of the voltage value of voltage HVH is referred to as voltage VHth2 and the lower limit voltage value is referred to as voltage VLth2. Similarly, the upper limit voltage value in the normal range of voltage value of voltage VDD is voltage VHth3 and lower limit voltage The value is referred to as voltage VLth3.

6. Monitoring of Constant Voltage, High Voltage, and Low Voltage Here, the monitoring operation of the voltage values of the voltages VBS, HVH, and VDD will be described with reference to FIGS. 11 to 13. In FIGS. 11 to 13, although the monitoring operation in the case where the voltage values of the voltages VBS, HVH, and VDD rise and exceed the normal voltage range will be described, each of the voltages VBS, HVH, and VDD is described. The monitoring operation is also the same when the voltage value of V falls and falls below the normal voltage range.

6.1 Monitoring Operation of Voltage VBS FIG. 11 is a timing chart showing a monitoring operation of the voltage VBS.

  In the present embodiment, the voltage VBS is monitored by the monitoring signal VBSmon to determine whether the voltage value is in the normal range.

  As shown in FIG. 11, before time t1a, the voltage VBS is output at a constant voltage value. At this time, the monitoring signal VBSmon is an H level signal indicating that the voltage value of the voltage VBS is a normal voltage. Then, at time t1a, the voltage value of the voltage VBS rises due to, for example, noise.

  At time t2a, when the voltage value of the voltage VBS exceeds the voltage VHth1 to become an abnormal voltage, the monitoring signal VBSmon becomes L level. As described above, the monitor signal VBSmon is input to the monitor signal determination circuit 213 (see FIG. 9). The monitoring signal determination circuit 213 determines whether to make the switch circuit 220 nonconductive by the switch control signal Ctrl based on the input monitoring signal VBSmon.

  Then, at time t3a, the monitoring signal determination circuit 213 changes the switch control signal Ctrl to the L level based on the monitoring signal VBSmon. Thereby, the switch circuit 220 becomes nonconductive. That is, the period from time t2a to time t3a corresponds to the time when the monitoring signal determination circuit 213 determines the monitoring signal VBSmon.

  In the present embodiment, the monitoring signal determination circuit 213 changes the switch control signal Ctrl to L level when the monitoring signal VBSmon is continuously at L level in a predetermined period (period from time t2a to t3a). However, the monitoring signal determination circuit 213 may change the switch control signal Ctrl to the L level based on the number of times the monitoring signal VBSmon has the L level within the predetermined period. Further, the monitoring signal determination circuit 213 may change the switch control signal Ctrl to the L level based on both the L level time and the number of times of the monitoring signal VBSmon. Furthermore, when the monitoring signal VBSmon is at the L level, the monitoring signal determination circuit 213 may notify the host computer or the like that the voltage value of the voltage VBS is an abnormal voltage.

  Further, at time t3a, the switch control signal Ctrl becomes L level and the switch circuit 220 becomes nonconductive, whereby the switch circuit 220 stops the output of the voltage HVH. That is, the monitoring signal VBSmon stops the supply of the voltage HVH when the value of the voltage VBS becomes a value different from the predetermined range.

  When the switch circuit 220 stops the output of the voltage HVH, the constant voltage generation circuit 322 operating based on the voltage HVH stops its operation. Thus, the voltage value of the voltage VBS gradually decreases. Similarly, the low voltage generation circuit 323 generating the voltage VDD also stops its operation, and the voltage value of the voltage VDD gradually decreases.

  As the voltage value of the voltage VBS gradually decreases, at time t4a, the voltage value of the voltage VBS falls below the voltage VHth1, and the voltage value of the voltage VBS assumes the normal voltage, and the monitoring signal VBSmon becomes H level. However, in the present embodiment, the monitoring signal determination circuit 213 continues the switch control signal Ctrl at the L level. Therefore, switch circuit 220 continues to stop the output of voltage HVH. As a result, the voltage HVH which is stopped because the voltage VBS is an abnormal voltage is prevented from being repeatedly detected as an abnormal voltage by starting the output again.

  When the voltage VBS changes from the abnormal voltage to the normal voltage, the switch control signal Ctrl may be set to the H level to resume the output of the voltage HVH. At this time, when the monitoring signal determination circuit 213 determines that the voltage VBS is an abnormal voltage a predetermined number of times within a predetermined period, the switch control signal Ctrl may continue to be at the L level.

  Then, at time t5a, assuming that the voltage value of the voltage VBS falls below the voltage VLth1 and the voltage VBS is an abnormal voltage, the monitoring signal VBSmon becomes L level, and then the operation is stopped.

  In the present embodiment, by constantly monitoring the voltage VBS applied to the electrode 612 of the piezoelectric element 60 by the constant voltage monitoring circuit 332, the piezoelectric element 60 resulting from the application of an abnormal potential difference across the piezoelectric element 60. It is possible to prevent the failure of the In particular, since the piezoelectric element 60 shown in this embodiment is configured such that the film thickness of the piezoelectric body 601 is 1 μm or less, the constant voltage monitoring circuit 332 constantly monitors the voltage VBS to prevent the failure of the piezoelectric element 60. It is possible to obtain more remarkable effects for

  Furthermore, since the voltage VBS is a signal of a constant voltage value in the normal voltage, it is possible to detect the voltage of the piezoelectric element 60 more accurately by detecting this voltage VBS, and the failure of the piezoelectric element 60 Can be prevented more efficiently.

6.2 HVH Voltage Abnormality Detection FIG. 12 is a timing chart showing a monitoring operation of the voltage HVH.

  In the present embodiment, the high voltage generation circuit 110 generates the voltage HVH. The generation of the voltage HVH is a voltage signal that contributes to the generation of the drive voltage Vout (drive voltages COM-A and COM-B) or the voltage VBS. The voltage HVH is monitored by the monitoring signal HVHmon, and the monitoring signal HVHmon stops the supply of the voltage HVH when the value of the voltage HVH becomes a value different from a predetermined range.

  As shown in FIG. 12, voltage HVH is output at a constant voltage value before time t1b. At this time, the monitoring signal HVHmon is an H level signal indicating that the voltage value of the voltage HVH is a normal voltage. Then, at time t1b, the voltage value of the voltage HVH rises due to, for example, noise.

  At time t2b, when the voltage value of the voltage HVH exceeds the voltage VHth2 and becomes an abnormal voltage, the monitoring signal HVHmon becomes L level. As described above, the monitoring signal HVHmon is input to the monitoring signal determination circuit 213 (see FIG. 9). The monitoring signal determination circuit 213 determines whether to make the switch circuit 220 nonconductive by the switch control signal Ctrl based on the input monitoring signal HVHmon.

  Then, at time t3b, the monitor signal determination circuit 213 changes the switch control signal Ctrl to L level based on the monitor signal HVHmon. Thereby, the switch circuit 220 becomes nonconductive. That is, the period from time t2b to time t3b corresponds to the time when the supervisory signal determination circuit 213 determines the supervisory signal HVHmon. It is preferable that the time when the monitoring signal determination circuit 213 determines the monitoring signal HVHmon is shorter than the time when the monitoring signal determination circuit 213 determines the monitoring signal VBSmon and the time when determining the monitoring signal VDDmon described later.

  The voltage value of voltage HVH has a large voltage value with respect to the voltage values of voltage VBS and voltage VDD. Therefore, when an abnormality occurs in the voltage HVH, there is a high possibility that various configurations of the liquid discharge device 1 may be broken compared to when an abnormality occurs in the voltage values of the voltage VBS and the voltage VDD. An abnormality caused by noise or the like in the liquid ejection device 1 by shortening the time for which the monitoring signal determination circuit 213 determines the monitoring signal HVHmon to the time for determining the monitoring signal VBSmon and the time for determining the monitoring signal VDDmon described later. It becomes possible to further reduce the possibility of occurrence of failure or the like when a voltage is generated.

  In the present embodiment, the monitoring signal determination circuit 213 changes the switch control signal Ctrl to L level when the monitoring signal HVHmon is continuously at L level in a predetermined period (period from time t2 b to t3 b). However, the monitoring signal determination circuit 213 may change the switch control signal Ctrl to the L level based on the number of times the monitoring signal HVHmon has the L level within the predetermined period. Also, the monitoring signal determination circuit 213 may change the switch control signal Ctrl to L level based on both the L level time and the number of times of the monitoring signal HVHmon. Furthermore, when the monitoring signal HVHmon is at the L level, the monitoring signal determination circuit 213 may notify the host computer or the like that the voltage value of the voltage HVH is an abnormal voltage.

  Further, at time t3b, the switch control signal Ctrl becomes L level and the switch circuit 220 becomes nonconductive, whereby the switch circuit 220 stops the output of the voltage HVH and the voltage value of the voltage HVH gradually decreases.

  As the voltage value of the voltage HVH gradually decreases, the voltage value of the voltage HVH falls below the voltage VHth2 at time t4 b, and the voltage value of the voltage HVH is the normal voltage, and the monitoring signal HVHmon becomes H level. However, in the present embodiment, the monitoring signal determination circuit 213 continues the switch control signal Ctrl at the L level. Therefore, switch circuit 220 continues to stop the output of voltage HVH.

  Then, at time t5b, assuming that the voltage value of the voltage HVH falls below the voltage VLth2 and the voltage HVH is an abnormal voltage, the monitoring signal HVHmon becomes L level and then the operation is stopped.

  The drive voltage Vout applied to the electrode 611 of the piezoelectric element 60 includes the drive voltages COM-A and COM-B amplified to the voltage level based on the voltage HVH. Therefore, when an abnormal voltage occurs in the voltage HVH, the abnormal voltage may be superimposed on the drive voltages COM-A and COM-B and the drive voltage Vout, and an abnormal potential difference may occur at both ends of the piezoelectric element 60.

  In the present embodiment, a piezoelectric element resulting from application of an abnormal potential difference across the piezoelectric element 60 by constantly monitoring the drive voltage COM-A, COM-B and the voltage HVH that is the basis of the drive voltage Vout. It becomes possible to prevent 60 failures.

  Furthermore, the voltage HVH is a signal having a voltage larger than the voltages VBS and VDD, and when an abnormal voltage occurs in the voltage HVH, the switch circuit 220 stops the supply thereof to eject the liquid due to the abnormal voltage. It is possible to reduce the possibility of the device 1 failing.

6.3 VDD Abnormality Detection FIG. 13 is a timing chart showing a monitoring operation of the voltage VDD.

  In the present embodiment, the voltage VDD for operating the drive signal selection circuit 510 generated by the low voltage generation circuit 323 is monitored by the monitoring signal VDDmon.

  As shown in FIG. 13, before time t1c, the voltage VDD is output at a constant voltage value. At this time, the monitoring signal VDDmon is an H level signal indicating that the voltage value of the voltage VDD is a normal voltage. Then, at time t1c, the voltage value of the voltage VDD rises due to, for example, noise.

  At time t2c, when the voltage value of the voltage VDD exceeds the voltage VHth3 and becomes an abnormal voltage, the monitoring signal VDDmon becomes L level. As described above, the monitoring signal VDDmon is input to the monitoring signal determination circuit 213 (see FIG. 9). Then, based on the input monitoring signal VDDmon, the monitoring signal determination circuit 213 determines whether or not the switch circuit 220 is to be nonconductive by the switch control signal Ctrl.

  Then, at time t3c, the monitoring signal determination circuit 213 changes the switch control signal Ctrl to the L level based on the monitoring signal VDDmon. Thereby, the switch circuit 220 becomes nonconductive. That is, the period from time t2c to time t3c corresponds to the time when the monitoring signal determination circuit 213 determines the monitoring signal VDDmon.

In the present embodiment, the supervisory signal determination circuit 213 performs a predetermined period (from time t2c to time t3).
In the period up to c), when the monitoring signal VDDmon is continuously at L level, the switch control signal Ctrl is changed to L level, but the monitoring signal determination circuit 213 monitors the monitoring signal VDDmon within a predetermined period. The switch control signal Ctrl may be changed to L level based on the number of times the signal VDDmon becomes L level. Also, the monitoring signal determination circuit 213 may change the switch control signal Ctrl to L level based on both the L level time and the number of times of the monitoring signal VDDmon. Furthermore, when the monitoring signal VDDmon is at the L level, the monitoring signal determination circuit 213 may notify the host computer or the like that the voltage value of the voltage VBS is an abnormal voltage.

  Further, at time t3c, the switch control signal Ctrl becomes L level and the switch circuit 220 becomes nonconductive, whereby the switch circuit 220 stops the output of the voltage HVH.

  When the switch circuit 220 stops the output of the voltage HVH, the constant voltage generation circuit 322 operating based on the voltage HVH stops its operation. Thus, the voltage value of the voltage VBS gradually decreases. Similarly, the low voltage generation circuit 323 generating the voltage VDD also stops its operation, and accordingly, the voltage value of the voltage VDD also gradually decreases.

  As the voltage value of the voltage VDD gradually decreases, the voltage value of the voltage VDD falls below the voltage VHth3 at time t4 c, and the monitoring signal VDDmon becomes H level assuming that the voltage value of the voltage VDD is a normal voltage. However, in the present embodiment, the monitoring signal determination circuit 213 continues the switch control signal Ctrl at the L level. Therefore, switch circuit 220 continues to stop the output of voltage HVH. As a result, the voltage HVH which is stopped because the voltage VDD is an abnormal voltage is prevented from being repeatedly detected as an abnormal voltage by starting the output again.

  When the voltage VDD changes from the abnormal voltage to the normal voltage, the switch control signal Ctrl may be set to the H level to resume the output of the voltage HVH. At this time, when the monitoring signal determination circuit 213 determines that the voltage VDD is an abnormal voltage a predetermined number of times within a predetermined period, the switch control signal Ctrl may continue to be at the L level.

  Then, at time t5a, assuming that the voltage value of the voltage VDD falls below the voltage VLth3 and the voltage VDD is an abnormal voltage, the monitoring signal VDDmon becomes L level, and then the operation is stopped.

7. Operation and Effect As described above, in the liquid ejection apparatus 1 according to the present embodiment, the constant voltage monitoring circuit 332 detects the voltage value of the voltage VBS, which is a voltage signal of a constant voltage value applied to the piezoelectric element 60. By monitoring with the monitoring signal VBSmon, application of an unintended voltage to the piezoelectric element 60 can be detected in advance and accurately. Thereby, application of an unintended voltage to the piezoelectric element 60 can be reduced.

  Moreover, in the liquid discharge device 1 according to the present embodiment, since it is possible to detect in advance that an unintended voltage is applied to the piezoelectric element 60, the piezoelectric element 60 has a thickness of 1 μm or less. Even with the body 601, an abnormal voltage is applied to the piezoelectric element 60, and the possibility of failure can be reduced.

Further, in the liquid ejection apparatus 1 according to the present embodiment, the high voltage monitoring circuit 331 detects the voltage HVH and monitors the voltage HVHmon with the monitoring signal HVHmon to thereby drive the driving voltages COM-A, COM-B (drive voltage Vout) and The possibility that the abnormal voltage is superimposed on the voltage VBS is reduced, and the abnormal voltage is applied to the piezoelectric element 60, thereby further reducing the possibility of occurrence of failure.

  Further, in the liquid discharge device 1 according to the present embodiment, when an abnormality occurs in the voltage HVH, the supply of the voltage HVH is stopped, so when the unintended voltage is superimposed on the voltage HVH, the drive circuits 311 and 312, The possibility of failure of the constant voltage generation circuit 322 and the low voltage generation circuit 323 is reduced.

  Further, in the liquid discharge apparatus 1 according to the present embodiment, the low voltage monitoring circuit 333 detects the voltage VDD for operating the drive signal selection circuit 510 that controls the application of the drive voltage Vout to the piezoelectric element 60, and the monitoring signal VDDmon. By monitoring with the above, an unintended voltage is superimposed on the voltage VDD, and the possibility of the drive signal selection circuit 510 malfunctioning is reduced. Therefore, the application accuracy of the drive voltage Vout to the piezoelectric element 60 can be improved.

8. Modification Example In the present embodiment, when the monitoring signal determination circuit 213 determines that the voltages VBS, HVH, and VDD are abnormal voltages, the drive circuit board is made nonconductive by the switch control signal Ctrl, and thus the drive circuit board Although the power supply to the ejection head 30 and the discharge head 40 is stopped, the sharing of the voltage HVH may be stopped by stopping the operation of the high voltage generation circuit 110. Thereby, even if abnormality occurs in the voltage oHVH input to the switch circuit 220, there is a possibility that the respective components provided on each of the control circuit board 20 and the drive circuit board 30 and the ejection head 40 may break down. It is possible to reduce.

  As mentioned above, although an embodiment and a modification were described, the present invention is not limited to these embodiments, and can be carried out in various modes in the range which does not deviate from the gist. For example, the above embodiments can be combined as appropriate.

  The invention includes configurations substantially the same as the configurations described in the embodiments (for example, configurations having the same function, method and result, or configurations having the same purpose and effect). The present invention also includes configurations in which nonessential parts of the configurations described in the embodiments are replaced. The present invention also includes configurations that can achieve the same effects or the same objects as the configurations described in the embodiments. Further, the present invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

DESCRIPTION OF SYMBOLS 1 ... Liquid discharge apparatus, 2 ... control part, 3 ... delivery part, 4 ... support part, 5 ... conveyance part, 6 ... printing part, 10 ... power supply circuit board, 20 ... control circuit board, 21 ... holder, 22 ... flange Parts, 23: fixed plate, 24: reinforcing plate, 23a, 24a: opening, 25: housing portion, 26: recess, 27: cover member, 28: opening, 29: connector, 30: drive circuit board, 31: holding member , 40: discharge head, 41: first support portion, 42: second support portion, 43: third support portion, 51: rotation mechanism, 52: conveyance roller, 53: driven roller, 60: piezoelectric element, 61: movement Mechanism 62, Guide member 63, Guide rail portion 64, Carriage support portion 65, 86, 87 Cable, 71 Carriage 72 Carriage body 73 Carriage cover 74 Connection board 75, 83 BtoB co KR, 76, 77, 84, 85: FFC connector, 81: heat dissipation case, 82: heat dissipation plate, 91: maintenance section, 92: cap, 110: high voltage generation circuit, 210: control circuit, 211: discharge data generation circuit 212: drive data generation circuit 213: supervisory signal determination circuit 220: switch circuit 311: drive circuit 312: drive circuit 322: constant voltage generation circuit 323: low voltage generation circuit 331: high voltage monitor circuit , 332: constant voltage monitoring circuit, 333: low voltage monitoring circuit, 351, 352, 353, 354: resistance, 361, 362: comparator, 500: ejection module, 510: driving signal selection circuit, 520: selection control circuit, 530 ... selection circuit, 600 ... ejection part, 601 ... piezoelectric body, 6
11, 612 Electrodes 621 Vibrators 631 Cavities 632 Nozzles Plates 641 Reservoirs 651 Nozzles 651a Nozzle Surfaces 661 Supply Port M Medium R, Roll Body

Claims (7)

A piezoelectric element to which a drive signal and a reference voltage signal are input and at least a part of which has a thickness of 1 μm or less;
A cavity whose internal volume is changed by displacement of the piezoelectric element;
A nozzle for discharging the liquid in the cavity according to a change in the internal volume of the cavity;
Have
The reference voltage signal is monitored by a first monitoring signal.
Liquid discharge device characterized by. A first power supply generation circuit generating a first power supply voltage for generating at least one of the drive signal and the reference voltage signal;
The first power supply voltage is monitored by a second monitoring signal,
When the value of the first power supply voltage is different from a predetermined range, the supply of the first power supply voltage is stopped based on the second monitoring signal.
The liquid discharge device according to claim 1, When the value of the reference voltage signal becomes different from a predetermined range, the supply of the first power supply voltage is stopped based on the first monitoring signal.
The liquid discharge device according to claim 2, When the value of the reference voltage signal is different from the predetermined range by 5% or more, the supply of the first power supply voltage is stopped based on the first monitoring signal.
The liquid discharge apparatus according to claim 2 or 3, wherein A detection circuit that detects the reference voltage signal or the first power supply voltage;
The detection circuit
A first comparator including a first input terminal, a second input terminal, and a first output terminal;
A second comparator including a third input terminal, a fourth input terminal, and a second output terminal;
Including
The reference voltage signal or a first detection voltage obtained by dividing the first power supply voltage is input to the first input terminal,
A reference voltage is input to the second input terminal,
The first comparator compares the first detection voltage with the reference voltage, and outputs a signal indicating a comparison result from the first output terminal.
The second detection voltage smaller than the first detection voltage is input to the third input terminal by dividing the reference voltage signal or the first power supply voltage.
The reference voltage is input to the fourth input terminal.
The second comparator compares the second detection voltage with the reference voltage, and outputs a signal indicating a comparison result from the second output terminal.
The detection circuit generates the first monitoring signal based on the signal output from the first output terminal and the signal output from the second output terminal.
The liquid discharge device according to any one of claims 2 to 4, characterized in that: A discharge control circuit that receives a discharge control signal and controls application of the drive signal to the piezoelectric element;
A second power supply generation circuit generating a second power supply voltage for operating the discharge control circuit;
The second power supply voltage is monitored by a third monitoring signal.
The liquid discharge device according to any one of claims 1 to 5, characterized in that: A piezoelectric element to which a drive signal and a reference voltage signal are input and at least a part of which has a thickness of 1 μm or less;
A cavity whose internal volume is changed by displacement of the piezoelectric element;
A nozzle for discharging the liquid in the cavity according to a change in the internal volume of the cavity;
A first power supply generation circuit for generating a first power supply voltage for generating at least one of the drive signal and the reference voltage signal;
A switch circuit located between the piezoelectric element and the first power generation circuit;
A first input terminal to which the reference voltage signal or the first power supply voltage is input via a first resistor;
A second input terminal to which a reference voltage is input;
A first output terminal electrically connected to the switch circuit;
A first comparator including
A third input terminal to which the reference voltage signal or the first power supply voltage is input via the first resistor and the second resistor;
A fourth input terminal to which the reference voltage is input;
A second output terminal electrically connected to the first output terminal and the switch circuit;
A second comparator including
A detection circuit having
A liquid discharge apparatus characterized by comprising:

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