Liquid ejection device

Abstract

To provide a liquid ejection device capable of suppressing, with a simple configuration, fixation of an ink within nozzles.SOLUTION: The liquid ejection device includes: an ejection head including a nozzle plate and a liquid supply path, wherein the nozzle plate has a first surface and a second surface on a side opposite the first surface, the first surface being provided with a plurality of nozzles and having ejection openings through which liquid is ejected from the nozzles, and the liquid supply path is arranged on the second surface side of the nozzle plate and configured to supply liquid to the nozzle; a storage case capable of storing the ejection head, on the first surface of the nozzle plate; and an ultrasonic generator that is provided in the storage case and configured to generate ultrasonic waves, wherein the ultrasonic generator is configured to, by the ultrasonic waves propagated to the nozzle plate through the storage case, generate standing waves inside the plurality of nozzles.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a liquid ejection device. [Background technology]

[0002] Conventionally, liquid ejection devices that eject liquid are known (see, for example, Patent Document 1). The liquid ejection device described in Patent Document 1 is an inkjet printer that ejects ink as a liquid from a nozzle. In the liquid ejection device of Patent Document 1, a heating element, a pressure detection element, and an ultrasonic vibrator are provided in the nozzle. The pressure detection element detects clogging of the nozzle, and cleaning liquid is supplied to the nozzle, the heating element heats the cleaning liquid, and the ultrasonic vibrator applies ultrasonic vibrations to clean the nozzle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2003-145782 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the liquid ejection device of Patent Document 1 requires an ultrasonic vibrator, a heating element, and a pressure detection element to be arranged for each nozzle, which results in a problem that the configuration of the nozzles and the liquid ejection head on which the nozzles are mounted becomes complicated, and the liquid ejection head becomes large. [Means for solving the problem]

[0005] A liquid ejection device according to one aspect of the present disclosure comprises a nozzle plate having a first surface on which a plurality of nozzles are provided and on which openings through which liquid is ejected from the nozzles are provided, an ejection head having a liquid supply path that supplies liquid to the nozzles, a storage case facing the first surface of the nozzle plate, and an ultrasonic generating mechanism provided in the storage case that generates ultrasonic waves, wherein the ultrasonic generating mechanism generates standing waves inside the plurality of nozzles by the ultrasonic waves that propagate to the nozzle plate via the storage case. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a schematic diagram showing the overall configuration of a liquid ejection device according to a first embodiment. [Figure 2] FIG. 1 is a block diagram showing a schematic configuration of a printer according to a first embodiment. [Figure 3] FIG. 2 is a schematic cross-sectional view showing a discharge mechanism in the discharge head of the first embodiment. [Figure 4] FIG. 2 is a diagram showing a schematic configuration of a part of the ejection head and the storage case in a state where the ejection head is stored in the storage case in the first embodiment. [Figure 5] FIG. 4 is a diagram showing an example of a standing wave formed in a nozzle in the first embodiment. [Figure 6] FIG. 10 is a diagram showing the relationship between the ultrasonic frequency and the sound pressure at the nozzle opening (+Z side end). [Figure 7] 10 is a flowchart illustrating a cleaning method in the printer according to the first embodiment. [Figure 8] FIG. 10 is a diagram showing a schematic configuration of a part of the ejection head and the storage case in a state where the ejection head is stored in the storage case in a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] [First embodiment] A liquid ejection device according to a first embodiment of the present disclosure will be described below. [General configuration of the printer 10] Fig. 1 is a diagram showing an example of the external configuration of a printer 10 according to this embodiment. Fig. 2 is a block diagram showing a schematic configuration of the printer 10 according to this embodiment. The printer 10 of this embodiment is an example of a liquid ejection device of the present disclosure, and is a device that ejects ink containing a coloring material as a liquid onto a medium A to form an image. 1, the printer 10 includes a supply unit 11, a transport unit 12, a discharge head 20, a head movement unit 13, a storage case 30, and a control unit 40 (see FIG. 2). The printer 10 controls the units 11, 12, and 13 and the discharge head 20 based on print data input from an external device (not shown), such as a personal computer, to print an image on the medium A. Each component of the printer 10 will be described in detail below.

[0008] The supply unit 11 is a unit that supplies medium A, on which an image is to be formed, to an image formation position. This supply unit 11 includes, for example, a roll body 111 on which medium A is wound, a roll drive motor (not shown), and a roll drive gear train (not shown). Based on a command from the control unit 40, the roll drive motor is driven to rotate, and the rotational force of the roll drive motor is transmitted to the roll body 111 via the roll drive gear train. This causes the roll body 111 to rotate, and the medium A wound on the roll body 111 is supplied to the +Y side. In this embodiment, an example in which paper surfaces wound on a roll body 111 are supplied is shown, but the present invention is not limited to this. For example, medium A such as paper surfaces loaded on a tray or the like may be supplied one sheet at a time using a roller or the like, or any other supply method may be used to supply medium A. Furthermore, the medium A of this embodiment may be paper such as printing paper, or may be film, cloth, or the like.

[0009] The transport unit 12 sends out the medium A supplied from the supply unit 11 to the +Y side. The transport unit 12 includes a transport roller 121, a driven roller (not shown) that is disposed with the medium A sandwiched between the transport roller 121 and the transport roller 121 and that follows the transport roller 121, and a platen 122. When a driving force is transmitted from a transport motor (not shown) and the transport motor is driven under the control of the control unit 40, the transport roller 121 is driven to rotate by the rotational force thereof, and transports the medium A along the Y direction with the medium A sandwiched between the transport roller 121 and the driven roller. In addition, a platen 122 facing the ejection head 20 is provided on the +Y side of the transport roller 121.

[0010] The head moving unit 13 moves the ejection head 20 back and forth along the X direction based on a command from the control unit 40 . The head moving unit 13 includes, for example, a carriage guide shaft 131 , a carriage motor 132 , and a timing belt 133 . The carriage guide shaft 131 is disposed along the X direction, and both ends are fixed to the housing of the printer 10. The carriage motor 132 drives a timing belt 133. The timing belt 133 is supported substantially parallel to the carriage guide shaft 131, and a portion of the ejection head 20 is fixed to the timing belt 133. When the carriage motor 132 is driven based on a command from the control unit 40, the timing belt 133 runs forward and reverse, and the ejection head 20 fixed to the timing belt 133 moves back and forth while being guided by the carriage guide shaft 131.

[0011] [Configuration of the ejection head 20] The ejection head 20 includes an ejection mechanism 21 and a liquid container 201. The liquid container 201 is, for example, an ink cartridge, which is detachably provided on the ejection head 20 and stores ink to be supplied to the ejection mechanism 21. In this embodiment, an ink cartridge is used as an example of the liquid container 201, but it may also be a bag-shaped ink pack made of a flexible film, an ink tank that can be refilled with ink, or the like.

[0012] Fig. 3 is a schematic cross-sectional view showing the ejection mechanism 21 in the ejection head 20. Fig. 4 is a diagram showing a part of the ejection head 20 and a schematic configuration of the storage case 30 when the ejection head 20 is stored in the storage case 30 in this embodiment. The direction of the dashed arrow in Fig. 3 indicates the direction in which ink, which is a liquid, flows. The ejection head 20 has a plurality of ejection mechanisms 21, as shown in Fig. 3, arranged in the X direction. The ejection mechanism 21 includes a nozzle plate 22 , a communication plate 23 , a common liquid chamber forming substrate 24 , a pressure chamber substrate 25 , a pressure applying plate 26 , and a sealing sheet 27 . In this embodiment, the liquid ejection direction in the ejection head 20 is defined as the Z direction, the direction perpendicular to the Z direction is defined as the X direction, and the direction perpendicular to the X and Z directions is defined as the Y direction. In this embodiment, a plurality of ejection mechanisms 21 shown in FIG. 3 are arranged in the X direction as shown in FIG.

[0013] The nozzle plate 22 is a plate-like member that is arranged so as to be approximately parallel to the XY plane when the medium A is transported to the printing position. Nozzles 221 that function as ejection ports for the ink liquid are formed in the nozzle plate 22. The nozzles 221 are through-holes provided in the nozzle plate 22. The nozzles 221 may be formed in the shape of a cylinder with an inner circumference that is parallel to the ink ejection direction, or may be formed so that the opening diameter narrows along the ink ejection direction. The +Z side surface of the nozzle plate 22 is the first surface of the present disclosure, and faces the storage case 30 when the ejection head 20 moves to the home position. The -Z side surface of the nozzle plate 22 is the second surface of the present disclosure, and the provision of the communication plate 23, the common liquid chamber forming substrate 24, the pressure chamber substrate 25, the pressure applying plate 26, and the sealing sheet 27 constitutes a liquid supply path through which ink flows. The nozzle plate 22 is common to the plurality of ejection mechanisms 21, and as shown in FIG. 4, the nozzle plate 22 is provided with a plurality of nozzles 221 aligned in the X direction.

[0014] The communication plate 23 is provided on the -Z side surface of the nozzle plate 22. The communication plate 23 is a plate-shaped member arranged to be approximately parallel to the XY plane. The communication plate 23 has a plurality of through holes formed therein, which form part of the in-head flow path F, which will be described later.

[0015] The common liquid chamber forming substrate 24 is provided on the -Z side surface of the communication plate 23. A first common liquid chamber F1 and a second common liquid chamber F2 are formed by the area surrounded by the common liquid chamber forming substrate 24 and the communication plate 23. A first through-hole 241 that penetrates the common liquid chamber forming substrate 24 is formed on the -Z side of the first common liquid chamber F1. The first common liquid chamber F1 is connected to the first flow path 281 via the first through-hole 241. Furthermore, a second through-hole 242 is formed on the -Z side of the second common liquid chamber F2. The second common liquid chamber F2 is connected to the second flow path 282 via the second through-hole 242.

[0016] The pressure chamber substrate 25 is a plate-like member provided on the -Z side surface of the communication plate 23. The pressure chamber substrate 25 is disposed so as to be approximately parallel to the XY plane. The pressure-applying plate 26 is a plate-like member provided on the -Z side surface of the pressure chamber substrate 25. The pressure-applying plate 26 is also an elastically vibrating member. The communicating plate 23, the pressure chamber substrate 25, and the pressure-applying plate 26 form pressure chambers F3 and F4. The pressure chambers F3 and F4 are spaces extending in the Y-axis direction. The pressure-applying plate 26 is disposed substantially parallel to the XY plane. Head-side piezoelectric elements PZ1 and PZ2 corresponding to the pressure chambers F3 and F4, respectively, are provided on the -Z side surface of the pressure-applying plate 26. The head-side piezoelectric elements PZ1 and PZ2 are energy conversion elements that convert electrical energy transmitted from the control unit 40 into kinetic energy. Displacement of the head-side piezoelectric elements PZ1 and PZ2 causes the pressure-applying plate 26 to bend, thereby applying pressure to the ink in the pressure chambers F3 and F4. The applied pressure causes ink to be ejected from the nozzles 221.

[0017] The sealing sheet 27 is provided on the +Z side surface of the communicating plate 23. For example, an elastic material is used for the sealing sheet 27. The sealing sheet 27 absorbs pressure fluctuations of the ink inside the in-head flow path F, which will be described later.

[0018] Within the ejection mechanism 21 of the ejection head 20, an in-head flow path F is formed by the aforementioned communicating plate 23, pressure chamber substrate 25, pressure applying plate 26, common liquid chamber forming substrate 24, and sealing sheet 27. The in-head flow path F is a flow path in the ejection head 20 through which ink supplied from the first flow path 281 is discharged to the second flow path 282. One end of the in-head flow path F is connected to the first flow path 281, and the other end is connected to the second flow path 282. Specifically, the in-head flow path F includes a first common liquid chamber F1, a second common liquid chamber F2, pressure chambers F3 and F4, a nozzle flow path F5, a first connection flow path F6, a second connection flow path F7, a third connection flow path F8, and a fourth connection flow path F9. The first connection flow path F6 is a flow path connecting the first common liquid chamber F1 and the pressure chamber F3. The second connection flow path F7 connects the pressure chamber F4 and the second common liquid chamber F2. The third connection flow path F8 connects the pressure chamber F3 and the nozzle flow path F5. The fourth connection flow path F9 connects the nozzle flow path F5 and the pressure chamber F4. The nozzle flow path F5 is a flow path that extends in the X-axis direction and is connected to the nozzle 221 near the center in the X-axis direction.

[0019] In this embodiment, the pump 283 supplies ink stored in the liquid container 201 from the first flow path 281 to the first common liquid chamber F1. The pump 283 also returns ink that has flowed out from the second common liquid chamber F2 to the second flow path 282 to the first flow path 281 and circulates the ink. Under the control of the control unit 40, the pump 283 can select one of the multiple types of ink stored in the liquid container and supply it to one ejection head 20. In other words, the ejection head 20 of this embodiment can be supplied with each of the multiple types of liquid individually by the control unit 40 switching the type of liquid. The first flow path 281, the second flow path 282, the pump 283, and the liquid container may be provided in the ejection head 20. Alternatively, the liquid container and the pump 283 may be separate from the ejection head 20, and the first flow path 281 and the second flow path 282 may be connected to the ejection head 20.

[0020] [Storage Case 30 Configuration] The storage case 30 is a member that faces the nozzle plate 22 of the ejection head 20 when the head moving unit 13 moves the ejection head 20 to the home position at the −X side end. 4, the storage case 30 includes a plurality of caps 31 facing the nozzle plate 22. Each cap 31 is provided facing a corresponding nozzle 221 of the nozzle plate 22. Each cap 31 includes a guide portion 311, an advancing / retreating portion 312 held by the guide portion 311 so as to be able to advance and retreat, a lid portion 313 arranged on the -Z side of the advancing / retreating portion 312, a sealing portion 314 arranged on the -Z side of the lid portion 313, and an advancing / retreating mechanism 315 that moves the advancing / retreating portion 312 forward and backward in the Z direction.

[0021] The guide portion 311 includes, for example, a side wall portion 311A ​​extending in the Z direction to guide the advance / retract movement of the advance / retract portion 312, a bottom surface portion 311B provided on the +Z side of the side wall portion 311A, and a top surface portion 311C provided on the -Z side of the side wall portion 311A. The top surface portion 311C faces the nozzle plate 22 when the ejection head 20 is moved to the home position. An opening 311D is provided in the top surface portion 311C, and the advance / retract portion 312 advances / retracts through the opening 311D into and out of the guide portion 311. An advance / retract mechanism 315 is provided between the advance / retract portion 312 inserted into the guide portion 311 and the bottom surface portion 311B.

[0022] The advancing / retreating part 312 is a member that holds the lid part 313 and the sealing part 314, and is moved forward and backward in the Z direction by an advancing / retreating mechanism 315. The lid portion 313 is a plate-like member that faces the nozzle 221 on the −Z side of the advancing / retreating portion 312, and is formed in the shape of a flat plate parallel to the XY plane. The sealing portion 314 is an annular member provided on the -Z side of the lid portion 313. When the ejection head 20 is moved to the home position and the advancing / retracting portion 312 is moved on the -Z side, the sealing portion 314 abuts against the nozzle plate 22 with the nozzle 221 positioned on the annular inner periphery of the sealing portion 314. As a result, as shown in FIG. 4 , the nozzle 221 is sealed by being surrounded by the lid portion 313 and the sealing portion 314. The sealing portion 314 is preferably made of an elastic material such as silicone rubber, and when the advancing / retracting portion 312 is moved on the -Z side and the sealing portion 314 is pressed against the nozzle plate 22, it elastically deforms and abuts against the nozzle plate 22 without any gaps.

[0023] The advancing / retreating mechanism 315 is a mechanism for moving the advancing / retreating unit 312 forward and backward in the Z direction. The specific configuration of the advancing / retreating mechanism 315 is not particularly limited. For example, the advancing / retreating mechanism 315 may be configured to include an engagement unit that restricts the movement of the advancing / retreating unit 312 and a biasing member such as a spring, and when the discharge head 20 moves to the home position, the restriction on movement by the engagement unit is released and the biasing member moves the advancing / retreating unit 312 to the -Z side. Alternatively, the advancing / retreating mechanism 315 may be configured by a motor or actuator that moves the advancing / retreating unit 312 in the Z direction by applying a voltage.

[0024] Furthermore, an ultrasonic wave generating mechanism 32 is provided in the storage case 30. The ultrasonic wave generating mechanism 32 includes an ultrasonic element 321 and a control circuit 322. The ultrasonic element 321 is provided on a part of the cap 31, for example, on the outer circumferential surface on the +Z side. For example, a bulk type piezoelectric element can be used as the ultrasonic element 321. When a drive voltage is applied to such a bulk type piezoelectric element, it vibrates, thereby propagating ultrasonic waves to the cap 31 of the storage case 30, and the ultrasonic waves are propagated from the cap 31 to the nozzle plate 22. The control circuit 322 is a control unit of the present disclosure, and generates a drive voltage to be output to the ultrasonic element 321 to drive the ultrasonic element 321. The control circuit 322 can also change the frequency of the drive voltage within a predetermined band, which makes it possible to change the frequency of the ultrasonic waves output from the ultrasonic element 321 within a predetermined frequency range. The ultrasonic waves generated by the ultrasonic element 321 are propagated to the nozzle plate 22 of the ejection head 20 and the ink in the in-head flow path F via the guide portion 311, the advance / retreat portion 312, the lid portion 313, and the sealing portion 314 of the cap 31. The ultrasonic waves form standing waves in the nozzles 221, making it possible to prevent foreign matter from adhering to the nozzles 221 and to remove any adhering foreign matter.

[0025] [Configuration of control unit 40] As shown in FIG. 2, the control unit 40 includes an I / F 41, a unit control circuit 42, a storage unit 43, and a processor 44. The I / F 41 inputs print data input from an external device to the processor 44 . The unit control circuit 42 includes control circuits that respectively control the supply unit 11, the transport unit 12, the head moving unit 13, the ejection head 20, and the storage case 30, and controls the operation of each unit based on command signals from the processor 44. Note that the control circuit for each unit may be provided separately from the control unit 40 and connected to the control unit 40. The storage unit 43 is an information storage device such as a semiconductor memory or a hard disk, and stores various programs and data that control the operation of the printer 10. The processor 44 reads out and executes various programs stored in the storage unit 43, thereby functioning as a scanning control unit 441, a printing control unit 442, a cleaning control unit 443, and the like.

[0026] The scanning control unit 441 outputs a command signal to the unit control circuit 42 to drive the supply unit 11, the transport unit 12, and the head moving unit 13. As a result, the unit control circuit 42 drives the roll drive motor of the supply unit 11 to supply the medium A to the transport unit 12. The unit control circuit 42 also drives the transport motor of the transport unit 12 to transport a predetermined area of ​​the medium A along the Y direction to a position facing the ejection head 20 on the platen 122. The unit control circuit 42 also drives the carriage motor 132 of the head moving unit 13 to move the ejection head 20 along the X direction.

[0027] The print control unit 442 controls printing by the ejection head 20 based on print data input from, for example, an external device. When a command signal is output from the print control unit 442 to the unit control circuit 42, the unit control circuit 42 outputs a print control signal including the position of the ejection mechanism 21 that causes the ejection head 20 to eject ink. This causes the ejection head 20 to drive the head-side piezoelectric elements PZ1, PZ2 of the corresponding ejection mechanism 21 to eject ink onto the medium A. Note that when printing is performed, the ejection head 20 is moved along the X direction, and during this movement, a dot formation operation in which ink is ejected from the nozzles 221 to form dots and a transport operation in which the medium A is transported in the Y direction are alternately repeated to print an image made up of a plurality of dots on the medium A.

[0028] The cleaning control unit 443 performs a cleaning process for the ejection head 20. For example, in the printer 10 of this embodiment, when print control is not being performed, the ejection head 20 is moved to the home position. When the ejection head 20 is moved to the home position, the cleaning control unit 443 moves the advance / retract unit 312 of the storage case 30 to the -Z side, brings the sealing unit 314 into contact with the nozzle plate 22, and seals the nozzles 221. Then, the cleaning control unit 443 outputs a command to the ultrasonic generation mechanism 32 to drive it at a preset frequency. This frequency is a frequency for forming standing waves in the ink in the nozzles 221 along the Z direction.

[0029] Fig. 5 is a diagram showing an example of a standing wave formed in nozzle 221. In Fig. 5, shading indicates the sound pressure of the standing wave, with dark areas indicating areas of high sound pressure centered around the position of the antinode, and light areas indicating areas of low sound pressure centered around the position of the node. 5 is formed inside the nozzle 221, and foreign matter floating in the ink is captured at the node position. This makes it possible to prevent foreign matter such as coloring material from solidifying inside the nozzle 221 and adhering to the wall surface of the nozzle 221. Even if foreign matter has already adhered to the nozzle 221, the ultrasonic waves will peel the foreign matter off from the nozzle 221 and move it to the node position.

[0030] Furthermore, in this embodiment, the cleaning control unit 443 outputs a command signal that commands the frequency of the ultrasonic waves to the control circuit 322. As a result, the control circuit 322 controls the frequency of the drive voltage output to the ultrasonic element 321 based on the command signal, and the frequency of the ultrasonic waves output from the ultrasonic element 321 changes periodically. FIG. 6 is a diagram showing the relationship between the frequency of the ultrasonic waves and the sound pressure at the opening (+Z side end) of the nozzle 221. In Fig. 6, the frequency at which the sound pressure reaches its maximum value means the frequency at which a standing wave is formed inside the nozzle 221. As shown in Fig. 6, there are multiple frequencies (f1 to f6 in Fig. 6) at which a standing wave can be formed, and each frequency has a different mode order. In other words, by switching the frequency at which a standing wave can be formed, the positions of the nodes and antinodes in the standing wave in the Z direction can be changed. The control of the ultrasonic frequency by cleaning control unit 443 may involve sweeping the ultrasonic frequency within a preset frequency band, or may involve sequentially switching frequencies that form standing waves (for example, f1 to f6 in FIG. 6).

[0031] [Nozzle cleaning method] Next, a cleaning method for the printer 10 of this embodiment will be described. FIG. 7 is a flowchart showing a cleaning method for the printer 10. In the printer 10 of this embodiment, after the printing process for the medium A is completed, the control unit 40 controls the head moving unit 13 to move the ejection head 20 to the home position (-X side end) (step S1). Next, the control unit 40 controls the advancing / retracting mechanism 315 of the storage case 30 to move the advancing / retracting part 312 to the -Z side, and brings the sealing part 314 of the cap 31 into contact with the nozzle plate 22 of the ejection head 20 (step S2).

[0032] Thereafter, the control unit 40 controls the ultrasonic wave generating mechanism 32 of the storage case 30 to continuously generate ultrasonic waves from the ultrasonic element 321 (step S3). The ultrasonic waves may be generated for a predetermined period of time. Alternatively, if the ejection head 20 has not moved from the home position, ultrasonic waves may be generated repeatedly at a constant interval. As described above, the ultrasonic waves generated by the ultrasonic element 321 are ultrasonic waves with a frequency that forms a standing wave in the Z direction in the ink in the nozzle 221, and are sequentially switched among multiple frequencies that can form a standing wave. Alternatively, the ultrasonic frequency may be swept within a predetermined frequency range. When the frequency of the standing wave is sequentially switched, the positions of the nodes and antinodes of the standing wave are periodically changed, and foreign matter floating in the ink moves in the Z direction accordingly. Furthermore, when the ultrasonic waves are swept within a predetermined frequency range, the ultrasonic waves are sequentially switched between a standing wave state in which a standing wave is formed and a non-standing wave state in which a standing wave is not formed. In each standing wave state, the positions of the nodes and antinodes differ depending on the mode order, as in the case of sequentially switching the ultrasonic frequency. Therefore, in this case as well, foreign matter floating in the ink moves in the Z direction. Therefore, foreign matter in the ink does not remain in one place (for example, the open end of the nozzle 221), and it is possible to prevent the foreign matter from solidifying and clogging the nozzle 221. Furthermore, even if foreign matter has already adhered to the nozzle 221, the sound pressure of the ultrasonic waves can peel the foreign matter off from the nozzle 221, thereby preventing clogging.

[0033] [Effects of this embodiment] The printer 10 of this embodiment includes an ejection head 20, a storage case 30, and a control unit 40. The ejection head 20 is provided with a plurality of nozzles 221, and includes a nozzle plate 22 having a first surface (+Z side surface) on which openings for ejecting ink from the nozzles 221 are provided, and a liquid supply path that supplies ink to the nozzles 221. The storage case 30 faces the +Z side surface of the nozzle plate 22. The ultrasonic wave generating mechanism 32 is provided in the storage case 30 and generates ultrasonic waves. The ultrasonic waves propagate to the nozzle plate 22 via the storage case 30, generating standing waves inside the plurality of nozzles 221. As a result, standing waves formed within the nozzle 221 capture foreign matter floating in the ink, preventing it from accumulating on the open end of the nozzle 221, thereby suppressing clogging due to foreign matter. Furthermore, the ultrasonic waves also peel off foreign matter adhering to the nozzle 221, further suppressing clogging. In addition, in this embodiment, the head-side piezoelectric elements PZ1 and PZ2 are not provided on the +Z side (coaxially) of the nozzle 221, so damage to the head-side piezoelectric elements PZ1 and PZ2 due to standing waves is also suppressed. Furthermore, although an ink meniscus forms at the open end (+Z side end) of the nozzle 221, this cannot follow the frequency of the ultrasonic waves, which suppresses the problem of ink dripping from the nozzle 221 due to the ultrasonic waves. In this embodiment, the ultrasonic wave generating mechanism 32 is provided in the storage case, which simplifies the configuration of the ejection head 20 compared to a configuration in which the ultrasonic wave generating mechanism 32 is provided in the ejection head 20.

[0034] In the printer 10 of this embodiment, at least a portion of the first surface of the nozzle plate 22 abuts against the storage case 30. This allows the ultrasonic waves generated by the ultrasonic generating mechanism 32 to be transmitted effectively from the storage case 30 to the nozzle plate 22, and allows standing waves to be generated within the nozzle 221.

[0035] In the printer 10 of this embodiment, the ultrasonic wave generating mechanism 32 includes an ultrasonic element 321 that transmits ultrasonic waves, and a control circuit 322 that controls the frequency of the ultrasonic waves generated from the ultrasonic element 321. This allows the frequency of the ultrasonic waves output from the ultrasonic element 321 to be controlled by the control circuit 322, and allows a standing wave to be formed in the nozzle 221.

[0036] In the printer 10 of this embodiment, the control circuit 322 drives the ultrasonic elements 321 at a plurality of different frequencies. This changes the mode order of the standing wave formed in nozzle 221, and the position of the node that captures the foreign matter can be moved in the Z direction. Therefore, the position where the foreign matter is captured in nozzle 221 changes, which reduces the inconvenience of the foreign matter being held and fixed at a specific position.

[0037] In the printer 10 of this embodiment, the ultrasonic element 321 is disposed on the outer surface of the storage case 30. In this case, a bulk type piezoelectric element can be used as the ultrasonic element 321, and the ultrasonic element 321 can be easily arranged in the storage case 30, thereby simplifying the configuration.

[0038] [Second embodiment] Next, a second embodiment will be described. In the first embodiment described above, a configuration example was shown in which the ultrasonic element 321 was arranged on the outer surface of the cap 31 in the storage case 30. In contrast, in the second embodiment, the arrangement position of the ultrasonic element 321 differs from that of the first embodiment. In the following description, the same components will be denoted by the same reference numerals, and their description will be omitted or simplified.

[0039] FIG. 8 is a diagram showing a schematic configuration of a part of the ejection head 20 and the storage case 30A in a state in which the ejection head 20 is stored in the storage case 30A in the second embodiment. As shown in Figure 8, the storage case 30A of this embodiment, like the first embodiment, has multiple caps 31A, and each cap 31A has a guide portion 311, an advancing / retreating portion 312A, a sealing portion 314, and an advancing / retreating mechanism 315. In this embodiment, an ultrasonic element 321A is provided at the -Z side end of the advancing / retreating portion 312A of each cap 31. Furthermore, the sealing portion 314 is provided on the -Z side surface of the ultrasonic element 321A. Therefore, in this embodiment, the distance from the ultrasonic element 321A to the nozzle plate 22 is shorter than in the first embodiment, and stronger ultrasonic waves can be propagated to the nozzle plate 22.

[0040] Furthermore, a control circuit 322 may be provided for each ultrasonic element 321A, or the same drive signal may be output to each ultrasonic element 321A from one control circuit 322. When the frequencies that form standing waves in each nozzle 221 are different and the frequencies of the ultrasonic waves that form the standing waves are switched sequentially, it is preferable to provide a control circuit 322 for each ultrasonic element 321A. On the other hand, when the frequency of the ultrasonic waves output from the ultrasonic element 321A is swept within a predetermined frequency range, the frequency of the ultrasonic waves output from each ultrasonic element 321A may be the same, and in this case, a driving voltage generated by one control circuit 322 may be output to each of the multiple ultrasonic elements 321A.

[0041] [Effects of this embodiment] In the printer of this embodiment, the storage case 30A has a plurality of caps 31A corresponding to the plurality of nozzles 221. The ultrasonic generating mechanism 32 has a plurality of ultrasonic elements 321A that transmit ultrasonic waves, and the plurality of ultrasonic elements 321A are arranged corresponding to the plurality of caps 31A, respectively. This allows ultrasonic waves corresponding to each nozzle 221 to be output from the corresponding ultrasonic element 321A.

[0042] [Variations] The present invention is not limited to the above-described embodiments, and includes modifications, improvements, and configurations obtained by appropriately combining the embodiments within the scope of achieving the object of the present invention.

[0043] [Variation 1] In the above embodiment, an example was shown in which ultrasonic waves generated by the ultrasonic generating mechanism 32 are propagated from the cap 31 to the ejection head 20 to form standing waves in the nozzle 221, but the present invention is not limited to this. For example, the open end of the nozzle 221 may be blocked by an ultrasonic transmission surface, and ultrasonic waves may be transmitted directly to the ink in the nozzle 221 from the ultrasonic transmission surface. In this case, in the storage case 30A of the second embodiment, a thin ultrasonic element that transmits ultrasonic waves by vibrating a vibration plate driven by a piezoelectric element is used as the ultrasonic element 321A provided in each cap 31A. Furthermore, the sealing portion 314 is not provided on the -Z side of the ultrasonic element 321A. When the advancing / retracting mechanism 315 moves the advancing / retracting portion 312A to the -Z side, the vibration plate of the ultrasonic element 321A is brought into contact with the nozzle plate 22. Furthermore, the ultrasonic element 321A is configured such that the piezoelectric element is disposed in an area facing the position of the open end of the nozzle 221. As a result, when the piezoelectric element is driven, the area of ​​the vibration plate surrounded by the open end of the nozzle 221 vibrates, and ultrasonic waves can be transmitted into the ink in the nozzle 221.

[0044] [Variation 2] In the above embodiment, a printer 10 was used as an example of a liquid ejection device, but this is not limiting. The liquid ejection device of the present disclosure can be applied to any device that ejects liquid from nozzles provided in an ejection head. For example, it can be applied to a configuration in which an ejection head for spraying pesticides or the like is stored in a storage case when the pesticide is not being sprayed. In this case, by providing an ultrasonic generating mechanism in the storage case, it is possible to prevent foreign matter from adhering to the nozzles in the ejection head and to prevent clogging.

[0045] Summary of this disclosure A liquid ejection device according to one aspect of the present disclosure comprises a nozzle plate having a first surface on which a plurality of nozzles are provided and on which openings are provided through which liquid is ejected from the plurality of nozzles, an ejection head having a liquid supply path that supplies liquid to the plurality of nozzles, a storage case facing the first surface of the nozzle plate, and an ultrasonic generating mechanism provided in the storage case that generates ultrasonic waves, wherein the ultrasonic generating mechanism generates standing waves inside the plurality of nozzles by the ultrasonic waves that propagate to the nozzle plate via the storage case. As a result, the standing waves generated inside the nozzle move foreign matter present in the liquid inside the nozzle to the node or antinode positions, thereby preventing the problem of foreign matter adhering to the open end of the nozzle, etc. Furthermore, foreign matter adhering to the nozzle can be peeled off by ultrasonic waves. This prevents nozzle clogging due to adhering foreign matter. Furthermore, since an ultrasonic wave generating mechanism is provided in the storage case, the configuration of the ejection head can be kept from becoming too complicated.

[0046] In the liquid ejection device of the present disclosure, it is preferable that at least a portion of the first surface of the nozzle plate abuts against the storage case. This allows ultrasonic waves to propagate from the storage case to the ejection head, generating standing waves in the nozzle.

[0047] In the liquid ejection device of the present disclosure, the ultrasonic wave generating mechanism preferably includes an ultrasonic element that transmits the ultrasonic waves, and a control unit that controls the frequency of the ultrasonic waves generated by the ultrasonic element. This allows the control unit to control the frequency of the ultrasonic waves output from the ultrasonic element, and allows standing waves to be formed in the nozzle.

[0048] In the liquid ejection device of the present disclosure, it is preferable that the control unit drives the ultrasonic element at a plurality of different frequencies. This allows a plurality of standing waves with different node and antinode positions to be generated sequentially within the nozzle, preventing foreign matter from remaining in one place within the nozzle and suppressing adhesion of the foreign matter.

[0049] In the liquid ejection device of the present disclosure, the ultrasonic element is preferably disposed on the outer surface of the storage case. By providing the ultrasonic element on the outer surface of the storage case, it is possible to prevent the storage case from becoming too complicated.

[0050] In the liquid ejection device of the present disclosure, the storage case may have a plurality of caps corresponding to each of the plurality of nozzles, the ultrasonic generating mechanism may include a plurality of ultrasonic elements that transmit ultrasonic waves, and the plurality of ultrasonic elements may be arranged to correspond to each of the plurality of caps. This allows ultrasonic waves corresponding to each nozzle to be output from the corresponding ultrasonic element. [Explanation of symbols]

[0051] 10...printer (liquid ejection device), 20...ejection head, 21...ejection mechanism, 22...nozzle plate, 23...communicating plate, 24...common liquid chamber forming substrate, 25...pressure chamber substrate, 26...pressure application plate, 27...sealing sheet, 30, 30A...storage case, 31, 31A...cap, 32...ultrasonic generating mechanism, 40...control unit, 221...nozzle, 311...guide portion, 311A...side wall portion, 311B...bottom portion, 311C...top portion, 311D...opening, 312...advance / retraction portion, 312A...advance / retraction portion, 313...lid portion, 314...sealing portion, 315...advance / retraction mechanism, 321, 321A...ultrasonic element, 322...control circuit (control unit), 443...cleaning control unit.

Claims

1. a nozzle plate having a first surface in which a plurality of nozzles are provided and openings through which liquid is ejected from the plurality of nozzles are provided, and a discharge head including a liquid supply channel for supplying liquid to the plurality of nozzles; a storage case facing the first surface of the nozzle plate; an ultrasonic generating mechanism provided in the storage case for generating ultrasonic waves; the ultrasonic wave generating mechanism generates standing waves inside the plurality of nozzles by the ultrasonic waves propagated to the nozzle plate through the storage case; Liquid discharge device.

2. At least a portion of the first surface of the nozzle plate abuts against the storage case. The liquid ejection device according to claim 1 .

3. The ultrasonic wave generating mechanism includes an ultrasonic element that transmits the ultrasonic waves, and a control unit that controls the frequency of the ultrasonic waves generated by the ultrasonic element. The liquid ejection device according to claim 1 .

4. The control unit drives the ultrasonic elements at a plurality of different frequencies. The liquid ejection device according to claim 3 .

5. The ultrasonic element is disposed on the outer surface of the housing. The liquid ejection device according to claim 3 .

6. the storage case has a plurality of caps corresponding to the plurality of nozzles, the ultrasonic generating mechanism includes a plurality of ultrasonic elements that transmit ultrasonic waves; The plurality of ultrasonic elements are arranged corresponding to the plurality of caps, respectively. The liquid ejection device according to claim 1 .

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