LIQUID EJECTION HEAD AND LIQUID EJECTION APPARATUS

Abstract

To detect an electrical connection failure when wiring for common voltage is included.SOLUTION: A liquid ejection head that ejects liquid includes: a connection unit that connects each wiring of a control source that controls liquid ejection; a first switch that cuts off electric connection of each wiring from the control source; a second switch selectively switches between application of a detection voltage from a detection power source and connection to the ground for each wiring for which the electric connection is cut off by the first switch; a control unit that executes control, in detection order of the wiring, of switching the second switch to apply a detection voltage to one piece of the wiring and to connect the ground to the remaining wiring; and a detection unit that detects an electric connection failure based on the potential of each wiring to which the inspection voltage is applied.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a liquid ejection head and a liquid ejection apparatus. [Background technology]

[0002] Conventionally, an inkjet head ejects ink droplets from a nozzle by driving a piezoelectric actuator. The inkjet head connects a connector portion of the inkjet head to a driving circuit, and the driving circuit drives the piezoelectric actuator.

[0003] When connecting the drive circuit and the inkjet head with a cable, the connector terminals may short-circuit and the circuit may be damaged due to ink adhering to the cable connector or improper fitting of the cable connector, etc. As a technology to prevent this, a technology for detecting short-circuits on the drive voltage side has been disclosed (see Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0004] However, some recent inkjet heads are driven by applying a common voltage to the negative electrode of the piezoelectric actuator, without connecting it to GND. In this case, the conventional method cannot detect a connection failure in the wiring for the common voltage, and there is a problem that the circuit may be damaged if there is a poor electrical connection there.

[0005] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a liquid ejection head and a liquid ejection device that are capable of detecting poor electrical connections when wiring for a common voltage is included. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems and achieve the object, a liquid ejection head that ejects liquid is characterized by having a connection unit that connects each wiring of a control source that controls the ejection of the liquid, a first switch that cuts off the electrical connection of each of the wirings from the control source, a second switch that selectively switches between applying an inspection voltage from an inspection power supply to each of the wirings whose electrical connection is cut off by the first switch and connecting the wiring to ground, a control unit that controls the second switch to apply the inspection voltage to one of the wirings and connect the remaining wirings to the ground in the order in which the wirings are inspected, and a detection unit that detects poor electrical connection based on the potential of each of the wirings to which the inspection voltage is applied. Effect of the Invention

[0007] According to the present invention, it is possible to effectively detect poor electrical connection when wiring for a common voltage is included. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view of an example of a liquid ejection head according to a first embodiment, taken along a longitudinal direction of a pressure chamber. [Diagram 2] FIG. 2 is a cross-sectional view taken along the line AA of FIG. 1, illustrating a cross section along the nozzle arrangement direction. [Diagram 3] FIG. 3 is a block diagram of an electric system of an example of a liquid ejection head. [Figure 4] FIG. 4 is a diagram showing an example of a configuration in which a test circuit is provided in a drive circuit. [Diagram 5] FIG. 5 is a diagram illustrating the operation of the drive circuit during inspection. [Figure 6] FIG. 6 is a diagram illustrating the operation of the drive circuit during normal operation after inspection. [Figure 7] FIG. 7 is a diagram showing an example of an operation flow of an inspection sequence. [Figure 8] FIG. 8 is an external view of a liquid ejection head as an example of a liquid ejection apparatus according to the second embodiment. [Figure 9]FIG. 9 is a cross-sectional view showing the internal configuration of the liquid ejection head of FIG. [Figure 10] FIG. 10 is a schematic explanatory diagram of a printing apparatus as an example of a liquid ejection apparatus. [Figure 11] FIG. 11 is a diagram showing an example of the configuration of a head provided with a plurality of sub-modules. [Figure 12] FIG. 12 is an explanatory diagram of a liquid circulating device that circulates liquid. [Figure 13] FIG. 13 is a plan view of a main part of a printing device according to a first modified example of the second embodiment. [Figure 14] FIG. 14 is a side view of the main part of FIG. [Figure 15] FIG. 15 is a front view illustrating a liquid ejection head according to the second modification. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of a liquid ejection head and a liquid ejection apparatus will be described in detail with reference to the accompanying drawings.

[0010] (First embodiment) (Liquid ejection head) 1 and 2 are diagrams showing an example of the ejection structure of a liquid ejection head according to a first embodiment. Fig. 1 is a cross-sectional view in the longitudinal direction of a pressure chamber of the liquid ejection head (a direction perpendicular to the nozzle arrangement direction). Fig. 2 is an AA cross-sectional view illustrating a cross section along the nozzle arrangement direction.

[0011] A liquid ejection head 100, which is an example of a liquid ejection head according to the first embodiment, is formed by laminating and bonding a nozzle plate 1, a flow path plate 2 which is an individual flow path member, and a vibration plate member 3 which serves as a wall member. The liquid ejection head 100 is provided with a piezoelectric actuator 11 which displaces a vibration region (vibration plate) 30 of the vibration plate member 3, and a common flow path member 20 which also serves as a frame member of the head.

[0012] The nozzle plate 1 has a plurality of nozzles 4 for ejecting liquid.

[0013] The flow path plate 2 has a plurality of pressure chambers 6 communicating with a plurality of nozzles 4, individual supply flow paths 7 which are individual flow paths communicating with each of the pressure chambers 6, and an intermediate supply flow path 8 which serves as a liquid introduction section communicating with one or a plurality (one in this embodiment) of individual supply flow paths 7. Here, the flow path plate 2 has a two-layer structure of a first flow path plate 2A and a second flow path plate 2B as an example, but is not limited to a two-layer structure.

[0014] The diaphragm member 3 has a plurality of displaceable diaphragms (vibration regions) 30 that form the wall surfaces of the pressure chambers 6 of the flow path plate 2. Here, as an example, the diaphragm member 3 has a two-layer structure made up of a first layer 3A that forms a thin portion from the flow path plate 2 side and a second layer 3B that forms a thick portion, but is not limited to a two-layer structure.

[0015] A deformable vibration region 30 is formed in the first layer 3A, which is a thin portion, in a portion corresponding to the pressure chamber 6. Within the vibration region 30, a convex portion 30a, which is a thick portion that is bonded to the piezoelectric actuator 11, is formed in the second layer 3B.

[0016] A piezoelectric actuator 11 including an electromechanical conversion element is disposed on the opposite side of the diaphragm member 3 to the pressure chamber 6 as a driving means (actuator means, pressure generating means) for deforming the vibration area 30 of the diaphragm member 3.

[0017] This piezoelectric actuator 11 is formed by forming grooves by half-cut dicing in a piezoelectric member bonded onto a base member 13, and forming a required number of columnar piezoelectric elements 12 in a comb shape at specified intervals in the nozzle arrangement direction. The piezoelectric elements 12 are bonded to protruding portions 30a, which are thick portions formed in the vibration region 30 of the vibration plate member 3.

[0018] This piezoelectric element 12 is formed by alternately laminating piezoelectric layers and internal electrodes, with the internal electrodes being drawn out to the end faces and connected to external electrodes (end face electrodes), and flexible wiring member 15 being connected to the external electrodes.

[0019] The common flow path member 20 forms a common supply flow path 10 that communicates with the multiple pressure chambers 6. The common supply flow path 10 communicates with an intermediate supply flow path 8 that serves as a liquid introduction section via an opening 9 provided in the vibration plate member 3, and communicates with the individual supply flow paths 7 via the intermediate supply flow path 8.

[0020] In this liquid ejection head 100, for example, by lowering the voltage applied to the piezoelectric element 12 from a reference potential (intermediate potential), the piezoelectric element 12 contracts, the vibration area 30 of the vibration plate member 3 is pulled, and the volume of the pressure chamber 6 expands, causing liquid to flow into the pressure chamber 6.

[0021] Thereafter, the voltage applied to the piezoelectric element 12 is increased to expand the piezoelectric element 12 in the stacking direction, and the vibration region 30 of the vibration plate member 3 is deformed in the direction toward the nozzle 4, thereby contracting the volume of the pressure chamber 6, whereby the liquid in the pressure chamber 6 is pressurized and the liquid is ejected from the nozzle 4.

[0022] (Drive circuit configuration) Fig. 3 is a block diagram of the electrical system of the liquid ejection head 100. As shown in Fig. 3, the liquid ejection head 100 has a drive circuit 200, and a flexible cable K of the liquid ejection head 100 is connected to a connector 250 of the drive circuit 200 to drive the liquid ejection head 100. Here, the flexible cable K is, for example, an FPC (Flexible Printed Circuits) cable, and is connected to various terminals on the liquid ejection head 100 side. The connector 250 corresponds to a "connection section." The IC 150 is a logic circuit that selectively switches a piezoelectric element to be driven from among the multiple piezoelectric elements 12.

[0023] For example, a main body control unit of a printing device or the like selects a waveform for large droplets, a waveform for medium droplets, or a waveform for small droplets for each nozzle of the liquid ejection head 100 based on image information and a print start command, and one of the drive waveforms is supplied to each piezoelectric element. In this example, the IC 150 selectively applies the drive waveform to each of the piezoelectric elements.

[0024] The flexible cable K includes a power supply wiring for supplying power to the IC 150, a wiring for outputting a drive voltage waveform to the piezoelectric element 12, and a wiring for outputting a common voltage to the piezoelectric element 12. When these electrical connections are normal, the corresponding wiring on the drive circuit 200 side and the liquid ejection head 100 side are connected, and the liquid ejection head 100 operates normally due to the drive circuit 200. The drive circuit 200 is provided with an inspection circuit that inspects each terminal in advance to ensure that the connections are normal when the liquid ejection head 100 is driven.

[0025] Fig. 4 is a diagram showing an example of a configuration in which a test circuit is provided in the drive circuit 200. The test circuit is a circuit for testing poor electrical connection of each terminal of the connector 250. The drive circuit 200 shown in Fig. 4 has a first drive voltage amplifier 211, a second drive voltage amplifier 212, a common voltage generator 213, and a power source 214 as a power supply unit 210 that controls the discharge of liquid from the liquid discharge head 100.

[0026] The first drive voltage amplifier 211 generates a first drive voltage by amplifying a first waveform signal input to the first drive voltage original waveform 201. The second drive voltage amplifier 212 generates a second drive voltage by amplifying a second waveform signal input to the second drive voltage original waveform 202. The common voltage generator 213 generates a common voltage.

[0027] 4 shows a typical configuration in which there is one liquid ejection head 100, for ease of explanation. In this example, two systems, a first driving voltage generated by a first driving voltage amplifier 211 and a second driving voltage generated by a second driving voltage amplifier 212, are output as voltages to be applied to the first electrodes of the piezoelectric elements 12 of the liquid ejection head 100. A common voltage is output as voltage to be applied to the second electrodes of the piezoelectric elements 12. A power source 214 supplies a power supply voltage to the IC 150. These output lines are respectively wired to two systems of driving voltage terminals, one system of common voltage terminal, and a power supply voltage terminal provided on the connector 250. In addition, the GND of the driving circuit 200 is wired to the ground (GND) terminal of the connector 250.

[0028] 4, the drive circuit 200 is provided with a first switch 221 that turns off the output from the power supply unit 210 to the subsequent stage. The first switch 221 is an electronic switch constituted by, for example, a transistor or a MOSFET, and the electrical connection between the power supply unit 210 and the subsequent stage is cut off by controlling the electronic switch. That is, when the first switch 221 is turned on, the power supply unit 210 and each wiring are electrically connected, and when the first switch 221 is turned off, each wiring is electrically cut off. Note that, as the first switch 221, an electronic switch is provided individually for each wiring of the power supply unit 210, but both of them perform the same switching operation.

[0029] Further, the driving circuit 200 is provided with an inspection circuit 300. The inspection circuit 300 mainly corresponds to a control unit 301, an inspection power supply unit 311, a second switch 321, an output line unit 331, an output potential measurement unit 341, a comparison unit 351, and a switch changeover generation unit 361. Of these, the output potential measurement unit 341, the comparison unit 351, and the switch changeover generation unit 361 mainly correspond to a "detection unit."

[0030] The control unit 301 executes an inspection sequence in the drive circuit 200. For example, when the liquid ejection head 100 is connected to the connector 250 via the bent cable K, the control unit 301 executes the inspection sequence to inspect for poor electrical connection of each terminal of the connector 250. If a poor electrical connection is found by executing the inspection sequence, the control unit 301 notifies the worker and has the worker check for adhesion of liquid to the terminal of the connector 250, poor fitting between the connector 250 and the bent cable K, etc.

[0031] When the output from power supply unit 210 is cut off, inspection power supply unit 311 applies an inspection voltage to each wiring of power supply unit 210. In this example, wiring for applying an inspection voltage from inspection power supply unit 311 is provided in correspondence with each wiring of power supply unit 210.

[0032] Corresponding lines of the wiring from power supply unit 210 and the wiring from inspection power supply unit 311 are connected to each other by output line unit 331. From output line unit 331 to connector 250, the output lines of power supply unit 210 to which the wiring from inspection power supply unit 311 is connected are wired.

[0033] The inspection power supply unit 311 applies a DC voltage generated from, for example, a secondary battery as the inspection voltage. The drive circuit 200 may be equipped with a secondary battery, or may receive power from an external source.

[0034] The second switch 321 is an individual switch that selectively switches between a test voltage applied by the test power supply unit 311 to each wiring of the output line unit 331 and a GND connection when the first switch 221 is turned off. This individual switch is an electronic switch that applies a test voltage from the test power supply unit 311 to the corresponding wiring when turned on, and connects the corresponding wiring to GND when turned off.

[0035] The output potential measuring unit 341 measures the potential of each wiring connected from the output line unit 331 to the connector 250, and outputs the measured potential to the comparing unit 351. The comparing unit 351 compares the potential measured by the output potential measuring unit 341 with a preset set potential, and outputs the comparison result to the switch changeover generating unit 361.

[0036] (Drive circuit operation) FIG. 5 is a diagram illustrating the operation of the drive circuit 200 during inspection, and FIG. 6 is a diagram illustrating the operation of the drive circuit 200 during normal operation after inspection.

[0037] (During inspection) The first switch 221 is initially off. When the first switch 221 of the drive circuit 200 is off as shown in FIG. 5, the output from the power supply unit 210 to the output line unit 331 is stopped. The control unit 301 uses the second switch 321 to inspect the electrical connection of each terminal of the connector 250. For example, the control unit 301 turns on one of the second switches 321 and turns off the remaining second switches 321, repeating this switching for all four of the second switches 321 in the order of wiring inspection. The order of wiring inspection may be set arbitrarily. Then, when the control unit 301 has finished switching all four of the second switches 321, it stops the supply from the inspection power supply unit 311 and disconnects all of them from each wiring. The timing at which the control unit 301 switches from one of the second switches 321 to another can be triggered by a switching signal output by the switch switching generation unit 361 on the condition that a comparison result is input to the switch switching generation unit 361.

[0038] The control unit 301 can obtain a comparison result indicating whether the wiring is within or outside the normal range together with the switching signal from the switch changeover generating unit 361, and can notify the operator when the wiring is outside the normal range. Here, when the wiring connection is normal, the potential of the output potential measuring unit 341 measured from the wiring to be inspected by application of the inspection voltage rises, so that the comparison unit 351 can determine that the wiring is normal because it exceeds the set potential of the normal threshold. When the wiring connection is faulty, the potential of the output potential measuring unit 341 measured from the wiring to be inspected by application of the inspection voltage falls below the set potential of the comparison unit 351, so that it can be determined that the electrical connection is faulty. For example, when the wiring to be inspected is short-circuited with another wiring due to adhesion of ink or poor fitting with a connector terminal, the potential of the output potential measuring unit 341 measured from the wiring to be inspected by application of the inspection voltage does not rise and remains at the GND level, so that it falls below the set potential of the comparison unit 351 and can be determined that the electrical connection is faulty. If the comparison result of the potential for each inspected terminal is within a normal range, the worker determines that the connection of the terminal is normal, and if it is outside the normal range, the worker determines that the connection of that terminal is defective.

[0039] (After the inspection) After the inspection, in response to an instruction from the main body control unit of, for example, a printing device, the control unit 301 turns on the first switch 221 as shown in FIG. 6, thereby starting output to the output line unit 331 by the power supply unit 210, and the liquid ejection head 100 performs normal liquid ejection operation.

[0040] Since poor electrical connections have been eliminated in advance by inspecting each terminal of connector 250, it is possible to prevent circuit damage caused by a short circuit between terminals when power supply unit 210 is turned on.

[0041] 7 is a diagram showing an example of an operation flow of an inspection sequence. When the liquid ejection head 100 is connected to the connector 250 via the flexible cable K during initial assembly or maintenance, the control unit 301 executes the inspection sequence at a predetermined timing. Note that the control unit 301 may execute the inspection sequence at other timings, such as at a timing instructed by the main body control unit.

[0042] 7(a), during testing, the control unit 301 first checks whether the first switch 221 is off (S1). In the initial state, the first switch 221 is off, but if the first switch 221 is not off, the control unit 301 turns off the first switch 221 and then performs the test.

[0043] Next, the control unit 301 turns on the switch 2-1 of the second switches 321, turns off the other switches 2-2 to 2-4 of the second switches 321, and inspects the wiring for short circuits with an inspection voltage (S2).

[0044] Next, the control unit 301 turns on the switch 2-2 of the second switch 321, turns off the other switches 2-1, 2-3, and 2-4 of the second switch 321, and inspects the wiring for short circuits with an inspection voltage (S3).

[0045] Next, the control unit 301 turns on the switch 2-3 of the second switch 321, turns off the other switches 2-1, 2-2, and 2-4 of the second switch 321, and inspects the wiring for short circuits with the inspection voltage (S4).

[0046] Next, the control unit 301 turns on the switch 2-4 of the second switch 321, turns off the other switches 2-1, 2-2, and 2-3 of the second switch 321, and inspects the wiring for short circuits with the inspection voltage (S5).

[0047] If there is a defective part such as a short circuit, the control unit 301 notifies that this is a poor electrical connection (S6), and ends this inspection sequence. In each of the inspections S2 to S5, the potential of the wiring is outside the normal range, for example, if there is a short circuit, it will be GND, which is outside the normal range, and in that case the control unit 301 notifies that connection is unnecessary. The notification means by which the control unit 301 notifies of a poor electrical connection may be, for example, a notification lamp that is provided and turned on, or the poor electrical connection and the terminal number of the defective part are displayed on the operation screen, or any other method that allows the operator to recognize the poor electrical connection may be appropriately set.

[0048] Fig. 7(b) is a diagram showing an example of a detailed sequence of each test of S2, S3, S4, and S5. As shown in Fig. 7(b), the control unit 301 turns on the switch 2-n of the second switches 321, turns off the switches of the second switches 321 other than the switch 2-n, and applies a test voltage to the wiring (S11). That is, the test voltage is applied to the wiring corresponding to the switch 2-n of the second switches 321, and the wiring corresponding to the remaining switches of the second switches 321 is connected to GND.

[0049] Next, the output potential measurement unit measures the potential of the wiring under test (S12), and the comparison unit compares the set voltage with the measured potential of the wiring and outputs the comparison result (S13).

[0050] Next, the switch changeover generating unit generates a switch changeover signal and outputs it to the control unit 301 (S14).

[0051] The first embodiment is also applicable to a case where a plurality of liquid ejection heads 100 are mounted as submodules. For example, there is a head array in which the liquid ejection heads 100 are arranged as submodules on a base member. If eight submodules are provided in the head array, the number of driving voltage systems x the number of submodules is 2 x 8, so there are 16 wirings for the driving voltage, and the number of wirings for the common voltage is 8, which is the number of submodules. In other words, an increase in the number of submodules increases the number of wirings connected to the driving circuit 200 via the bent cable K. The driving circuit 200 is provided with a number of second switches corresponding to the respective wirings, and each second switch is switched in sequence.

[0052] As described above, even when a common voltage is used, the inspection circuit can check that the wiring is not short-circuited before using the liquid ejection head, thereby preventing overcurrent caused by a short circuit in the wiring from flowing through the drive circuit and the liquid ejection head, thereby protecting the drive circuit and the liquid ejection head.

[0053] (Second embodiment) Next, a liquid ejection apparatus will be described using a printing apparatus as an example of a second embodiment. Note that a circulation type liquid ejection head is used as the liquid ejection head 100 of the printing apparatus as an example.

[0054] Figures 8 and 9 are diagrams showing the configuration of a liquid ejection head 100 of a liquid ejection device according to a second embodiment. Figure 8 is an external view of the liquid ejection head 100, and Figure 9 is a cross-sectional view showing the internal configuration of the liquid ejection head 100. In Figures 8 and 9, the same elements as in Figure 1 are given the same numbers, and only the differences from the first embodiment will be described.

[0055] The liquid ejection head 100 is formed by laminating and joining a nozzle plate 1, a flow path plate 2, and a vibration plate member 3 serving as a wall member. It also includes a piezoelectric actuator 11 that displaces a vibration region (vibration plate) 30 of the vibration plate member 3, and a common flow path member 20 that also serves as a frame member of the head.

[0056] The flow path plate 2 forms a plurality of pressure chambers 6 each connected to a plurality of nozzles 4 via a nozzle connecting passage 5, a plurality of individual supply flow paths 7 each connected to the plurality of pressure chambers 6 and also serving as fluid resistance sections, and one or more intermediate supply flow paths 8 serving as liquid introduction sections connected to two or more individual supply flow paths 7.

[0057] The individual supply flow path 7 includes two flow path sections, a first flow path section 7A and a second flow path section 7B, which have a higher fluid resistance than the pressure chamber 6, and a third flow path section 7C, which is arranged between the first flow path section 7A and the second flow path section 7B and has a lower fluid resistance than the first flow path section 7A and the second flow path section 7B.

[0058] The flow path plate 2 is formed by stacking a plurality of plate-like members 2A to 2E, but is not limited to this.

[0059] In addition, the flow path plate 2 forms a plurality of individual recovery flow paths 57 along the surface direction of the flow path plate 2, each of which is connected to a plurality of pressure chambers 6 via a nozzle connecting passage 5, and an intermediate recovery flow path 58 which serves as one or more liquid discharge portions connected to two or more individual recovery flow paths 57.

[0060] The individual recovery flow path 57 includes two flow path sections, a first flow path section 57A and a second flow path section 57B, which have a higher fluid resistance than the pressure chamber 6, and a third flow path section 57C, which is disposed between the first flow path section 57A and the second flow path section 57B and has a lower fluid resistance than the first flow path section 57A and the second flow path section 57B. In the individual recovery flow path 57, a flow path section 57D, which is downstream of the second flow path section 57B in the circulation direction, has the same flow path width as the third flow path section 57C.

[0061] The common flow path member 20 forms a common supply flow path 10 and a common recovery flow path 50. In this embodiment, the common supply flow path 10 is composed of a flow path portion 10A that is aligned with the common recovery flow path 50 in the nozzle arrangement direction, and a flow path portion 10B that is not aligned with the common recovery flow path 50.

[0062] The common supply flow path 10 communicates with an intermediate supply flow path 8 serving as a liquid introduction portion through an opening 9 provided in the vibration plate member 3, and communicates with the individual supply flow paths 7 through the intermediate supply flow path 8. The common recovery flow path 50 communicates with an intermediate recovery flow path 58 serving as a liquid outlet portion through an opening 59 provided in the vibration plate member 3, and communicates with an individual recovery flow path 57 through the intermediate recovery flow path 58.

[0063] In addition, the common supply flow path 10 communicates with a supply port 71 , and the common recovery flow path 50 communicates with a recovery port 72 .

[0064] Other aspects such as the layer configuration of the diaphragm member 3 and the configuration of the piezoelectric actuator 11 are similar to those in the first embodiment.

[0065] In this liquid ejection head 100, as in the first embodiment, the piezoelectric element 12 is stretched in the stacking direction, and the vibration area 30 of the vibration plate member 3 is deformed in a direction toward the nozzle 4 to contract the volume of the pressure chamber 6, thereby pressurizing the liquid in the pressure chamber 6 and ejecting the liquid from the nozzle 4.

[0066] Furthermore, liquid that is not ejected from the nozzles 4 passes through the nozzles 4, is recovered from the individual recovery flow paths 57 to the common recovery flow path 50, and is then re-supplied from the common recovery flow path 50 to the common supply flow path 10 via an external circulation path. Even when liquid is not being ejected from the nozzles 4, liquid circulates from the common supply flow path 10 to the common recovery flow path 50 via the pressure chambers 6, and is then re-supplied to the common supply flow path 10 via an external circulation path.

[0067] In this embodiment as well, the pressure fluctuations caused by liquid ejection can be attenuated and propagation to the common supply flow path 10 and the common recovery flow path 50 can be suppressed with a simple configuration.

[0068] Figures 10 to 12 are explanatory diagrams of the overall configuration of a liquid ejection device. Figure 10 shows a schematic explanatory diagram of a printing device as an example of a liquid ejection device. Figure 11 shows an example of the configuration of a head provided with multiple sub-modules. Figure 12 is an explanatory diagram of a liquid circulation device that circulates liquid.

[0069] The printing device 500 includes a carry-in means 501 for carrying in a continuous web 510, a guide / conveyance means 503 for guiding and conveying the continuous web 510, such as continuous paper or a sheet material, carried in from the carry-in means 501 to a printing means 505, the printing means 505 for printing the continuous web 510 by ejecting liquid onto the continuous web 510 to form an image, a drying means 507 for drying the continuous web 510, and a conveyance means 509 for conveying the continuous web 510. Here, the continuous web 510 is an example of "something to which liquid can adhere". The carry-in means 501, the guide / conveyance means 503, and the conveyance means 509 are examples of a "conveyance control unit".

[0070] The continuous body 510 is sent out from the original winding roller 511 of the carrying-in means 501 , guided and transported by the rollers of the carrying-in means 501 , the guiding and transporting means 503 , the drying means 507 , and the carrying-out means 509 , and taken up by the take-up roller 591 of the carrying-out means 509 .

[0071] This continuous body 510 is transported in the printing means 505 on a transport guide member opposite the head unit 550 and head unit 555, an image is formed by liquid ejected from the head unit 550, and post-processing is performed with processing liquid ejected from the head unit 555.

[0072] Here, in the head unit 550, for example, full line type head arrays 551A, 551B, 551C, and 551D for four colors (hereinafter, referred to as "head array 551" when no distinction is made between colors) are arranged from the upstream side in the transport direction.

[0073] Each head array 551 ejects liquid of black K, cyan C, magenta M, or yellow Y onto the transported continuum 510. Note that the types and number of colors are not limited to these.

[0074] The head array 551 is, for example, a configuration in which the liquid ejection heads 100, which are sub-modules, are arranged in a staggered pattern on a base member 552, but is not limited to this.

[0075] Next, an example of a liquid circulation device will be described. Although only one liquid ejection head 100 is shown in Fig. 12, when multiple sub-modules are arranged, the supply side liquid path and the recovery side liquid path will be connected to the supply side and recovery side of the multiple sub-modules, respectively, via a manifold or the like.

[0076] The liquid circulation device 600 is composed of a supply tank 601, a recovery tank 602, a main tank 603, a first liquid feed pump 604, a second liquid feed pump 605, a compressor 611, a regulator 612, a vacuum pump 621, a regulator 622, a supply side pressure sensor 631, and a recovery side pressure sensor 632.

[0077] Here, the compressor 611 and the vacuum pump 621 constitute a means for generating a pressure difference between the pressure in the supply tank 601 and the pressure in the recovery tank 602 .

[0078] The supply-side pressure sensor 631 is located between the supply tank 601 and the liquid ejection head 100, and is connected to a supply-side liquid path connected to the supply port 71 of the liquid ejection head 100. The recovery-side pressure sensor 632 is located between the liquid ejection head 100 and the recovery tank 602, and is connected to a recovery-side liquid path connected to the recovery port 72 of the liquid ejection head 100.

[0079] One side of the recovery tank 602 is connected to the supply tank 601 via a first liquid feed pump 604 , and the other side of the recovery tank 602 is connected to the main tank 603 via a second liquid feed pump 605 .

[0080] As a result, liquid flows into the liquid ejection head 100 from the supply tank 601 through the supply port 71, is recovered into the recovery tank 602 through the recovery port 72, and the liquid is sent from the recovery tank 602 to the supply tank 601 by the first liquid delivery pump 604, thereby forming a circulation path through which the liquid circulates.

[0081] Here, a compressor 611 is connected to the supply tank 601 and is controlled so that a supply side pressure sensor 631 detects a predetermined positive pressure. On the other hand, a vacuum pump 621 is connected to the recovery tank 602 and is controlled so that a recovery side pressure sensor 632 detects a predetermined negative pressure.

[0082] This makes it possible to circulate the liquid through the liquid ejection head 100 while maintaining a constant negative pressure at the meniscus.

[0083] Furthermore, when liquid is ejected from the nozzles 4 of the liquid ejection head 100, the amount of liquid in the supply tank 601 and the recovery tank 602 decreases. Therefore, the second liquid feed pump 605 is used to replenish the recovery tank 602 with liquid from the main tank 603 as appropriate.

[0084] The timing of refilling the liquid from the main tank 603 to the recovery tank 602 can be controlled based on the detection results of a liquid level sensor installed in the recovery tank 602, such as refilling the liquid when the liquid level in the recovery tank 602 falls below a predetermined level.

[0085] In the liquid ejection device according to the second embodiment, the driving circuit for driving the liquid ejection head 100 can be provided in the same manner as in the first embodiment. The control unit 301 may be provided in the control unit of the liquid ejection device main body. The description of the other driving circuits is a repetition of the description of the first embodiment, so the description here will be omitted.

[0086] (Modification 1 of the second embodiment) As a first variation of the printing device 500, a serial type device will be described. FIG. 13 is a plan view of the main parts of a printing device 500 according to the first modified example, and FIG. 14 is a side view of the main parts.

[0087] This printing device 500 is a serial type device, and a carriage 403 is reciprocated in the main scanning direction by a main scanning movement mechanism 493, which is an example of a "transport control unit". The main scanning movement mechanism 493 includes a guide member 401, a main scanning motor 405, a timing belt 408, etc. The guide member 401 is hung between left and right side plates 491A and 491B to movably hold the carriage 403. The carriage 403 is reciprocated in the main scanning direction by the main scanning motor 405 via a timing belt 408 hung between a drive pulley 406 and a driven pulley 407.

[0088] A liquid ejection unit 440, which integrates a liquid ejection head 100 and a head tank 441, is mounted on this carriage 403. The liquid ejection head 100 of the liquid ejection unit 440 ejects liquid of each color, for example, yellow (Y), cyan (C), magenta (M), and black (K). The liquid ejection head 100 is mounted with a nozzle row made up of a plurality of nozzles arranged in a sub-scanning direction perpendicular to the main scanning direction, and the ejection direction facing downward.

[0089] The liquid ejection head 100 is connected to a liquid circulation device 600 (see FIG. 12), and liquid of a desired color is circulated and supplied.

[0090] The printing apparatus 500 includes a transport mechanism 495 for transporting the paper 410. The transport mechanism 495 includes a transport belt 412, which is a transport means, and a sub-scanning motor 416 for driving the transport belt 412.

[0091] The conveyor belt 412 attracts the paper 410 and conveys it to a position facing the liquid ejection head 100. The conveyor belt 412 is an endless belt, and is stretched between a conveyor roller 413 and a tension roller 414. The paper can be attracted by electrostatic attraction or air suction.

[0092] The conveyor belt 412 moves in a circular motion in the sub-scanning direction as the conveyor rollers 413 are rotated by a sub-scanning motor 416 via a timing belt 417 and a timing pulley 418 .

[0093] Furthermore, a maintenance and recovery mechanism 420 for performing maintenance and recovery of the liquid ejection head 100 is disposed on one side of the conveyor belt 412 on one side of the carriage 403 in the main scanning direction.

[0094] The maintenance and recovery mechanism 420 is composed of, for example, a cap member 421 that caps the nozzle surface (surface on which nozzles are formed) of the liquid ejection head 100, a wiper member 422 that wipes the nozzle surface, and the like.

[0095] The main scanning movement mechanism 493, the maintenance and recovery mechanism 420, and the transport mechanism 495 are attached to a housing including side plates 491A and 491B and a back plate 491C.

[0096] In the printing device 500 configured in this manner, the paper 410 is fed onto the conveyor belt 412 and adsorbed thereon, and the paper 410 is conveyed in the sub-scanning direction by the circular movement of the conveyor belt 412.

[0097] Therefore, by driving the liquid ejection head 100 in response to an image signal while moving the carriage 403 in the main scanning direction, liquid is ejected onto the stationary paper 410 to form an image.

[0098] (Variation 2) The liquid ejection head 100 may be provided in combination with various accessory parts. FIG. 15 is a front view of a liquid ejection head provided as a liquid ejection head according to the second modification.

[0099] The liquid ejection unit 440 is composed of a liquid ejection head 100 to which a flow path part 444 is attached, and a tube 456 connected to the flow path part 444 .

[0100] The flow path part 444 is disposed inside the cover 442. A head tank 441 may be included instead of the flow path part 444. Furthermore, a connector 443 for electrically connecting with the liquid ejection head 100 is provided on the upper part of the flow path part 444.

[0101] Although not shown in the figure, all of the flexible cables K of the drive circuit 200 are connected to the connector 443 .

[0102] In the present application, the liquid to be ejected may have a viscosity and surface tension that allows it to be ejected from the head, and is not particularly limited, but it is preferable that the viscosity of the liquid is 30 mPa·s or less at room temperature and pressure, or by heating or cooling. More specifically, the liquid may be a solution, suspension, emulsion, etc., containing a solvent such as water or an organic solvent, a colorant such as a dye or pigment, a functionalizing material such as a polymerizable compound, a resin, or a surfactant, a biocompatible material such as DNA, amino acids, proteins, or calcium, an edible material such as a natural colorant, etc., and these can be used for applications such as inkjet ink, surface treatment liquid, liquid for forming components of electronic elements or light-emitting elements, electronic circuit resist patterns, material liquid for three-dimensional modeling, etc.

[0103] Energy sources for ejecting liquid include piezoelectric actuators (laminated piezoelectric elements and thin-film piezoelectric elements), thermal actuators that use electrothermal conversion elements such as heating resistors, and electrostatic actuators consisting of a vibration plate and an opposing electrode.

[0104] A "liquid ejection unit" is one form of a liquid ejection head. A liquid ejection unit is a liquid ejection head integrated with functional parts and mechanisms, and includes a collection of parts related to ejecting liquid. For example, a "liquid ejection unit" includes a combination of a liquid ejection head with at least one of the following components: a head tank, a carriage, a supply mechanism, a maintenance and recovery mechanism, a main scanning movement mechanism, and a liquid circulation device.

[0105] Here, integration includes, for example, a liquid ejection head, a functional part, and a mechanism that are fixed to each other by fastening, bonding, engaging, etc., and one is held movably relative to the other. Also, the liquid ejection head, the functional part, and the mechanism may be configured to be detachable from each other.

[0106] For example, there are liquid ejection units in which the liquid ejection head and the head tank are integrated together, and there are also liquid ejection units in which the liquid ejection head and the head tank are integrated together by being connected to each other by a tube, etc. Here, a unit including a filter can be added between the head tank and the liquid ejection head of these liquid ejection units.

[0107] Furthermore, there is a liquid ejection unit in which the liquid ejection head and the carriage are integrated.

[0108] In some liquid ejection units, the liquid ejection head is movably supported by a guide member that constitutes a part of the scanning movement mechanism, and the liquid ejection head and the scanning movement mechanism are integrated together, and in some liquid ejection units, the liquid ejection head, the carriage, and the main scanning movement mechanism are integrated together.

[0109] Furthermore, there is a liquid ejection unit in which a cap member, which is part of the maintenance and recovery mechanism, is fixed to a carriage on which the liquid ejection head is attached, thereby integrating the liquid ejection head, carriage, and maintenance and recovery mechanism.

[0110] In addition, some liquid ejection units have a head tank or a liquid ejection head to which a flow path component is attached, and a tube is connected to the liquid ejection head, integrating the liquid ejection head with a supply mechanism. Liquid is supplied from a liquid storage source to the liquid ejection head via this tube.

[0111] The main scanning movement mechanism includes the guide member alone, and the supply mechanism includes the tube alone and the loading unit alone.

[0112] The term "liquid ejection device" includes devices that have a liquid ejection head (also called a liquid ejection unit) and eject liquid by driving the liquid ejection head. Devices that eject liquid include not only devices that can eject liquid onto objects to which the liquid can adhere, but also devices that eject liquid into air or liquid.

[0113] This "liquid ejection device" can also include a transport control means related to the feeding, transport, and discharge of objects onto which liquid can be attached, as well as other pre-processing devices and post-processing devices.

[0114] For example, examples of "liquid ejection devices" include image forming devices that eject ink to form an image on paper, and three-dimensional modeling devices that eject modeling liquid onto a powder layer formed by layering powder in order to create a three-dimensional object (a three-dimensional model).

[0115] Furthermore, the term "liquid ejection device" is not limited to devices that visualize meaningful images such as characters and figures by ejecting liquid. For example, the term also includes devices that form patterns that have no meaning in themselves and devices that create three-dimensional images.

[0116] The above-mentioned "object to which liquid can adhere" means an object to which liquid can adhere at least temporarily, and to which the liquid adheres and sticks, or to which the liquid adheres and penetrates, etc. Specific examples include media such as paper, recording paper, film, cloth, and other recording media, electronic boards, electronic components such as piezoelectric elements, powder layers, organ models, and test cells, and unless otherwise specified, includes all objects to which liquid can adhere.

[0117] The material of the above-mentioned "object to which liquid can adhere" may be any material to which liquid can adhere even temporarily, such as paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, and ceramics.

[0118] Furthermore, the term "liquid ejection device" includes devices in which a liquid ejection head and an object to which liquid can be attached move relatively, but is not limited to this. Specific examples include serial type devices in which a liquid ejection head moves, and line type devices in which a liquid ejection head does not move.

[0119] Other examples of "liquid ejection devices" include a treatment liquid application device that ejects a treatment liquid onto paper to apply the treatment liquid to the surface of the paper for purposes such as modifying the surface of the paper, and an injection granulation device that ejects a composition liquid in which raw materials are dispersed through a nozzle to granulate fine particles of the raw materials.

[0120] In the present application, the terms image formation, recording, printing, imprinting, printing, modeling, and the like are all synonymous.

[0121] Although several embodiments and modifications of the present invention have been described above, these embodiments and modifications are presented as examples and are not intended to limit the scope of the invention. These novel embodiments and modifications can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. Each of these embodiments and modifications is included in the scope and gist of the invention, and is included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0122] 11 Piezoelectric Actuator 12 Piezoelectric element 100 Liquid ejection head 150 IC 200 Drive circuit 201 First driving voltage original waveform 202 Second driving voltage original waveform 210 Power supply section 211 First driving voltage amplifier 212 Second driving voltage amplifier 213 Common voltage generator 214 Power supply 221 First Switch 250 Connector 300 Inspection Circuit 301 Control Unit 311 Inspection power supply unit 321 Second Switch 331 Output line section 341 Output potential measurement section 351 Comparison Section 361 Switch Changeover Generation Unit 500 printing equipment 501 Means of transport 503 Guide and conveying means 505 Printing means 507 Drying means 509 Export means 510 Continuum K bent cable [Prior art documents] [Patent documents]

[0123] [Patent Document 1] JP 2010-69787 A

Claims

1. A liquid ejection head that ejects liquid, a connection section for connecting each wiring of a control source that controls the ejection of the liquid; A first switch that cuts off an electrical connection of each of the wirings from the control source; a second switch that selectively switches between application of a test voltage from a test power supply and connection to a ground for each of the wirings that are electrically disconnected by the first switch; a control unit that performs control to switch the second switch in an order in which the wirings are to be inspected, so as to apply the inspection voltage to one of the wirings and connect the remaining wirings to the ground; a detection unit that detects an electrical connection failure based on a potential of each of the wirings to which the inspection voltage is applied; A liquid ejection head comprising:

2. Each of the control source wirings includes wiring for driving a piezoelectric actuator for discharging the liquid, The wiring for driving the piezoelectric actuator includes a wiring for a drive voltage applied to a first electrode of the piezoelectric actuator and a wiring for a common voltage applied to a second electrode of the piezoelectric actuator. The liquid ejection head according to claim 1 .

3. Wiring for a driving voltage applied to the first electrode of the piezoelectric actuator includes a wiring for a first driving voltage and a wiring for a second driving voltage. The liquid ejection head according to claim 2 .

4. The wiring for driving the piezoelectric actuator includes a power supply wiring to an IC that selects a piezoelectric actuator to be driven from among the plurality of piezoelectric actuators.

4. The liquid ejection head according to claim 2.

5. A liquid ejection head according to any one of claims 1 to 4, a conveyance control unit that performs conveyance control for discharging the liquid from the liquid discharge head onto an object onto which the liquid can be adhered; A liquid ejection device comprising:

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