Cleaning device

Abstract

The present invention relates to a cleaning device that improves the removal force for removing adhering matter. The cleaning device is used for cleaning a nozzle plate that has a jet surface and is formed with a plurality of nozzles that jet a liquid, and includes a cover that is disposed so as to oppose the jet surface and has a recess, the cover being capable of storing the liquid in a space surrounded by the recess and the jet surface; an ultrasonic device that is provided to the cover, the ultrasonic device radiating ultrasonic waves toward the jet surface; and a control section, the ultrasonic device having a plurality of first ultrasonic transducers that radiate ultrasonic waves of a first frequency, i.e., first ultrasonic waves, and a plurality of second ultrasonic transducers that radiate ultrasonic waves of a second frequency that is lower than the first frequency, i.e., second ultrasonic waves, the control section causing the ultrasonic device to radiate the second ultrasonic waves after causing the ultrasonic device to radiate the first ultrasonic waves in a state in which the space is storing the liquid.

Description

Technical Field

[0001] This disclosure relates to cleaning apparatus. Background Technology

[0002] Conventional techniques include using ultrasound to remove deposits adhering to the nozzle of a sprayed liquid (e.g., Patent Document 1). In the apparatus of Patent Document 1, an ultrasonic transducer is installed in a cover covering the spray nozzle, and ultrasonic waves are emitted from the transducer when the space between the spray nozzle and the ultrasonic transducer is filled with liquid. This removes the deposits through the effect of cavitation.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2006-347000

[0004] The requirement is to improve the removal power of adhering substances. Summary of the Invention

[0005] According to one aspect of this disclosure, a cleaning apparatus is provided for cleaning a nozzle plate having a spray surface and forming a plurality of nozzles for spraying liquid. The cleaning apparatus comprises: a cover configured to face the spray surface and having a recess, the cover being capable of storing liquid in a space surrounded by the recess and the spray surface; an ultrasonic device disposed on the cover, the ultrasonic device emitting ultrasonic waves toward the spray surface; and a control unit, the ultrasonic device having a plurality of first ultrasonic transducers and a plurality of second ultrasonic transducers, the plurality of first ultrasonic transducers emitting first ultrasonic waves of a first frequency, the plurality of second ultrasonic transducers emitting second ultrasonic waves of a second frequency lower than the first frequency, the control unit, while the space contains liquid, emitting the first ultrasonic waves by the ultrasonic device, and then emitting the second ultrasonic waves by the ultrasonic device. Attached Figure Description

[0006] Figure 1 This is a schematic diagram showing a simplified structure of a liquid injection device.

[0007] Figure 2 This is an exploded 3D view of the liquid jet nozzle.

[0008] Figure 3 This is a schematic diagram of a portion of the liquid spray head and a cross-section of the cleaning device.

[0009] Figure 4 This is a diagram illustrating an acoustic lens.

[0010] Figure 5 This is a top view showing the overall structure of the ultrasonic device.

[0011] Figure 6 This is a top view showing the detailed structure of the ultrasonic device.

[0012] Figure 7 yes Figure 6 Sectional view along line VII-VII.

[0013] Figure 8 yes Figure 6 Sectional view along line VIII-VIII.

[0014] Figure 9 It is a three-dimensional diagram showing the relationship between the channel and the nozzle.

[0015] Figure 10 It is a waveform diagram of a sudden signal.

[0016] Figure 11 This is a diagram illustrating the relationship between sudden signals and ultrasound.

[0017] Figure 12 This is a flowchart illustrating the cleaning process.

[0018] Figure 13 This is a diagram illustrating the cleaning method.

[0019] Figure 14 This is a top view showing the overall structure of the ultrasonic device according to the second embodiment.

[0020] Figure 15 This is a top view showing the overall structure of the ultrasonic device according to the third embodiment.

[0021] Figure 16 This is a top view showing the detailed structure of the ultrasonic device according to the fourth embodiment.

[0022] Figure 17 yes Figure 16 Sectional view along line XVII-XVII.

[0023] Explanation of reference numerals in the attached figures

[0024] 8…ultrasonic transducer, 8A…first ultrasonic transducer, 8B…second ultrasonic transducer, 12…medium, 14…liquid container, 16…conveying mechanism, 20…head moving mechanism, 21…conveyor belt, 22…carriage, 26…liquid jet head, 32…connecting substrate, 33…connecting part, 33a…first opening, 33b…second opening, 33c…third opening, 34…pressure chamber substrate, 35…opening, 36…vibrating plate, 44…piezoelectric element, 46…sealing body, 46a…sealing body opening, 48…housing part, 48a…through hole, 50…circuit board, 51…electrical wiring, 62…nozzle plate, 62a…jet surface, 64…vibration absorber, 70…cleaning material Washing device, 71… cover, 71a… recess, 72… gasket, 73… acoustic lens, 80… ultrasonic device, 81… first substrate, 81a… opening, 81b… wall, 82… first electrode, 83… piezoelectric element, 84… second electrode, 85… vibrating plate, 86… second substrate, 87… column, 90… control unit, 100… liquid jetting device, 441… lower electrode, 442… piezoelectric layer, 443… upper electrode, Atg… object range, C… pressure chamber, CH… channel, DC… ultrasonic transducer array, DE… attachment, FP… supply flow path, G1… first interval, G2… second interval, GP1… first group, GP2… second group, LQ… liquid. Detailed Implementation

[0025] A. First implementation method: A1. Overall structure of the liquid injection device: Figure 1 This is a schematic diagram showing a simplified structure of the liquid jetting device 100 in the embodiment. The liquid jetting device 100 is an inkjet printing device that performs printing by jetting droplets of liquid ink onto a medium 12. The medium 12 can be any material such as resin film or cloth, in addition to printing paper. In the following description, the X, Y, and Z directions, which are orthogonal to each other, are used. Furthermore, when the orientation is determined, the positive direction is designated as "+", and the negative direction as "-", and the directions are marked with positive and negative symbols. In this embodiment, the X direction is the movement direction of the liquid jetting head 26, i.e., the main scanning direction. The Y direction is the media transport direction orthogonal to the main scanning direction, i.e., the sub-scanning direction. The -Z direction is the ink jetting direction. In the following description, the +Z direction is sometimes referred to as "up" and the -Z direction as "down".

[0026] The liquid jetting device 100 includes a liquid jetting head 26, a head moving mechanism 20, a liquid receiving section 14, a conveying mechanism 16, a cleaning device 70, and a control section 90.

[0027] The liquid container 14 contains the ink supplied to the liquid jet head 26. The liquid container 14 can be a bag-shaped liquid bag formed of a flexible membrane, an ink can that can be replenished, or an ink cartridge that can be loaded and unloaded.

[0028] The liquid ejector head 26 has multiple nozzles N for ejecting ink. The multiple nozzles N are arranged along the Y direction. The liquid ejector head 26 ejects ink supplied from the liquid container 14 from the multiple nozzles N toward the medium 12.

[0029] The head moving mechanism 20 includes a conveyor belt 21 and a carriage 22 that houses the liquid injection head 26. The carriage 22 is connected to the conveyor belt 21 and reciprocates in the X direction as the conveyor belt 21 is driven. The conveying mechanism 16 conveys the medium 12 in the +Y direction.

[0030] The cleaning device 70 removes and cleans the residue DE adhering to the liquid nozzle 26. Residue DE typically refers to the solidified residue of pigments or other colorants remaining after the solvent in the ink has evaporated. The presence of residue DE can cause the nozzle N to become clogged, resulting in ink blockage and ink being ejected off-track. Therefore, it is necessary to remove the residue DE from the liquid nozzle 26.

[0031] The control unit 90 includes one or more processing circuits such as a CPU (Central Processing Unit), an FPGA (Field Programmable Gate Array), and storage circuits such as semiconductor memory. The control unit 90 controls the overall operation of the liquid jetting device 100. The control unit 90 is electrically connected to the conveying mechanism 16, the head moving mechanism 20, the liquid jetting head 26, and the cleaning device 70, and controls each of these components. Liquid from the nozzle N is jetted onto the medium 12 conveyed by the conveying mechanism 16, thereby printing an image onto the medium 12.

[0032] A2. Structure of the liquid injection head: Figure 2 This is an exploded perspective view of the liquid injection head 26 according to the embodiment, as shown below. Figure 2As shown, the liquid injection head 26 includes a nozzle plate 62, two vibration absorbers 64, a connecting substrate 32, a pressure chamber substrate 34, a sealing body 46, a housing portion 48, and a circuit board 50. The nozzle plate 62, vibration absorbers 64, connecting substrate 32, pressure chamber substrate 34, and sealing body 46 are elongated plate-shaped components in the Y direction. The nozzle plate 62, connecting substrate 32, pressure chamber substrate 34, and sealing body 46 each have a substantially linearly symmetrical structure with respect to their centerline in the X direction. The top view dimensions of the pressure chamber substrate 34 and sealing body 46 are smaller than the top view dimensions of the connecting substrate 32 and housing portion 48. During assembly, the nozzle plate 62, the two vibration absorbers 64, the connecting substrate 32, the pressure chamber substrate 34, the sealing body 46, and the housing portion 48 are stacked in this order and bonded together, for example, by adhesive.

[0033] Nozzle plate 62 is a plate-shaped component having a plurality of nozzles N. Each nozzle N is a through-hole with a generally circular shape when viewed from above. The plurality of nozzles N are arranged along the Y direction. Two rows of nozzles N are arranged side-by-side along the X direction. Two vibration absorbers 64 are flexible membranes configured to clamp nozzle plate 62 in the X direction.

[0034] The connecting substrate 32 has a connecting portion 33. The connecting portion 33 includes two first openings 33a, a plurality of second openings 33b, and a plurality of third openings 33c. The top view of the first opening 33a is a long quadrilateral in the Y direction. The first opening 33a is formed along the edge of the connecting substrate 32 parallel to the Y direction. The plurality of second openings 33b are arranged in the Y direction. Similarly, the plurality of third openings 33c are arranged in the Y direction. There are two columns of second openings 33b and two columns of third openings 33c. In the X direction, the first openings 33a, a column of one second opening 33b, a column of one third opening 33c, a column of one second opening 33b, and the first opening 33a are formed side by side in this order. In addition, adjacent second openings 33b and third openings 33c in the X direction are formed in a manner that is substantially the same in position in the Y direction.

[0035] A plurality of openings 35 are formed on the surface of the pressure chamber substrate 34 opposite to the connecting substrate 32. The top view of each opening 35 is that of a long, rectangular quadrilateral in the X direction. The plurality of openings 35 are arranged in the Y direction. Two rows of openings 35 are arranged side-by-side in the X direction. It should be noted that the openings 35 are formed at positions that overlap with the adjacent second opening 33b and third opening 33c formed on the connecting substrate 32 when viewed from the Z direction.

[0036] A piezoelectric element 44 is formed on the surface of the pressure chamber substrate 34 opposite to the sealing body 46. The sealing body 46 strengthens the pressure chamber substrate 34 and protects the piezoelectric element 44. The sealing body 46 has a sealing body opening 46a and a sealing body recess. The top view of the sealing body opening 46a is a long quadrilateral in the Y direction. The sealing body recess is formed to be recessed from the surface of the sealing body 46 opposite to the piezoelectric element 44.

[0037] A drive circuit (not shown) for driving the piezoelectric element 44 is mounted on the circuit board 50. The drive circuit is implemented by an IC (Integrated Circuit) chip that outputs a drive signal for driving the piezoelectric element 44 and a reference voltage. The drive circuit and the piezoelectric element 44 are electrically connected via electrical wiring (not shown).

[0038] The housing portion 48 is a shell for storing ink and has a frame shape. When stacked, a pressure chamber substrate 34, a vibrating plate 36, and a sealing body 46 are arranged in the internal space of the housing portion 48. Through holes 48a are formed at both ends of the housing portion 48 in the X direction.

[0039] A3. Structure of the cleaning device: Figure 3 This is a schematic diagram of a portion of the liquid spray head 26 and a cross-section of the cleaning device 70. It should be noted that... Figure 3 The image shows the state in which a cover 71 for cleaning device 70 is fitted onto the liquid spray head 26 for cleaning purposes. Figure 3 It is a cross-sectional view with the plane passing through the center of nozzle N and parallel to the YZ plane as the cutting plane.

[0040] It should be noted that a cover 71 is provided relative to one nozzle row formed by multiple nozzles N arranged in the Y direction. In the following description, the cover 71 corresponding to one of the two nozzle rows of the liquid injection head 26 will be described.

[0041] like Figure 3 As shown, nozzle N has an opening on one side of nozzle plate 62, namely the spray surface 62a. A connecting substrate 32, a pressure chamber substrate 34, and a vibrating plate 36 are stacked on the side of nozzle plate 62 opposite to the spray surface 62a. A pressure chamber C and a supply flow path FP from pressure chamber C to nozzle N are formed through the pressure chamber substrate 34 and the connecting substrate 32. The vibrating plate 36 defines the pressure chamber C. Specifically, the pressure chamber C is defined by the sealing recess of the pressure chamber substrate 34, and the vibrating plate 36 is part of the pressure chamber substrate 34. Furthermore, the supply flow path FP is defined by the connecting portion 33 of the connecting substrate 32. A piezoelectric element 44 is formed on the side of vibrating plate 36 opposite to the side defining the pressure chamber substrate 34.

[0042] The piezoelectric element 44 has a lower electrode 441, a piezoelectric layer 442, and an upper electrode 443. The lower electrode 441, piezoelectric layer 442, and upper electrode 443 are stacked in this order. The lower electrode 441 and upper electrode 443 are configured to contain metal. For example, the piezoelectric layer 442 is configured to contain lead zirconate titanate (PZT). In this embodiment, when viewed from above along the Z-direction from the top of the vibrating plate 36, the upper electrode 443 is not separated for each piezoelectric element 44, but is formed in a manner covering the plurality of nozzles N arranged side-by-side in the Y-direction. Furthermore, the lower electrode 441 is separated for each piezoelectric element 44. When a voltage is applied between the lower electrode 441 and the upper electrode 443, the piezoelectric layer 442 deforms. Accompanying the deformation of the piezoelectric layer 442, the vibrating plate 36 vibrates.

[0043] Ink is supplied to pressure chamber C via a flow path not shown. Ink is ejected from nozzle N by pressure changes in pressure chamber C caused by the vibration of vibrating plate 36.

[0044] The cleaning device 70 includes a cover 71, an ultrasonic device 80, and a control unit 90. It should be noted that the control unit 90 does not only control the cleaning device 70, but controls the entire liquid spraying device 100. For example, in the cleaning process described later, the control unit 90 controls the head movement mechanism 20 and the cleaning device 70, etc. Strictly speaking, the control unit of the cleaning device 70 refers to the functional unit within the control unit 90 that performs the cleaning process described later; however, in this application's description, this distinction is not made in detail, and "control unit 90" is used. As mentioned above, for example, the functional unit within the control unit 90 that performs the cleaning process described later can be implemented by a CPU executing a program stored in a storage circuit, that is, using software; it can also be implemented using dedicated hardware such as an FPGA; or both.

[0045] The cover 71 is configured to move to a position where it abuts against the nozzle plate 62 via a moving mechanism (not shown). Figure 3 The assembly position and the release position of the cover 71 away from the nozzle plate 62 are shown. During cleaning, the liquid injection head 26 moves to the position where the cover 71 is positioned. If the liquid injection head 26 moves to the position where the cover 71 is positioned, the cover 71 moves to abut against the nozzle plate 62.

[0046] The cover 71 is configured to face the spray surface 62a. The cover 71 has a recess 71a. The cover 71 is configured to store liquid LQ in the space surrounded by the recess 71a and the spray surface 62a. The material of the cover 71 is, for example, stainless steel, synthetic resin, etc.

[0047] A gasket 72 made of an elastic material is provided at the periphery of the cover 71. The material of the cover 71 is, for example, rubber. By providing the gasket 72, leakage of liquid LQ stored in the recess 71a can be suppressed. It should be noted that the cover 71 is provided with a discharge path (not shown) for discharging the stored liquid LQ.

[0048] An acoustic lens 73 and an ultrasonic device 80 are stacked on the bottom surface of the defined recess 71a of the cover 71, opposite to the jet surface 62a.

[0049] Figure 4 This is a diagram illustrating the acoustic lens 73. Figure 4 This is a cross-sectional view with a plane passing through the center of nozzle N and parallel to the XZ plane as the cutting plane. The acoustic lens 73 focuses the ultrasonic waves onto the jet surface 62a within a lens focusing range (not shown). The lens focusing range is preset to include multiple nozzles N. Furthermore, the length of the lens focusing range in the X direction, which is the second direction, is predetermined. Specifically, as... Figure 4 As shown, the surface of the acoustic lens 73 opposite to the nozzle N is a curved surface that convexes toward the nozzle N. The acoustic lens 73 is manufactured such that, when ultrasonic waves emitted from the ultrasonic device 80 are incident, it forms a transmission path that concentrates the ultrasonic waves emitted from the ultrasonic device 80 into the lens focusing range.

[0050] Figure 5 This is a top view showing the overall structure of the ultrasonic device 80. (As shown) Figure 5 As shown, the ultrasonic device 80 has a plurality of ultrasonic transducers 8. The plurality of ultrasonic transducers 8 includes a plurality of first ultrasonic transducers 8A and a plurality of second ultrasonic transducers 8B. The first ultrasonic transducers 8A emit a first ultrasonic wave of a first frequency. The second ultrasonic transducers 8B emit a second ultrasonic wave of a second frequency. The frequency of the second ultrasonic wave is lower than the frequency of the first ultrasonic wave. In this embodiment, the frequency of the first ultrasonic wave is approximately 1 MHz or more and approximately 10 MHz or less. Furthermore, the frequency of the second ultrasonic wave is approximately 100 kHz or more and approximately 1 MHz less.

[0051] An ultrasonic transducer 8 is formed on the first substrate 81, which will be described later. In this embodiment, the ultrasonic transducers 8 are arranged in a matrix. Furthermore, the plurality of ultrasonic transducers 8 are divided into a first group GP1 consisting of a plurality of first ultrasonic transducers 8A and a second group GP2 consisting of a plurality of second ultrasonic transducers 8B. The first group GP1 and the second group GP2 are adjacent to each other in the Y direction.

[0052] As described later, a channel CH is formed by multiple ultrasonic transducers 8 arranged side by side in the X direction. The channel CH formed by the first ultrasonic transducer 8A is also called the first channel CHA. The channel CH formed by the second ultrasonic transducer 8B is also called the second channel CHB.

[0053] Figure 6 This is a top view showing the detailed structure of the ultrasonic device 80. The ultrasonic device 80 has a first substrate 81, a plurality of first electrodes 82, a plurality of piezoelectric elements 83, and a plurality of second electrodes 84. The first electrodes 82, piezoelectric elements 83, and second electrodes 84 are sequentially stacked on the first substrate 81. The first electrodes 82 and second electrodes 84 are configured to contain metal. The piezoelectric elements 83 are configured, for example, to contain lead zirconate titanate.

[0054] In this embodiment, the top view of each first electrode 82, when viewed along the Z direction, is a rectangle that is longer in the X direction. Similarly, the top view of each second electrode 84 is a rectangle that is longer in the Y direction. The first electrode 82 and the second electrode 84 are respectively wound around an end of the first substrate 81. Furthermore, the first electrode 82 and the second electrode 84 are electrically connected to terminals formed at the ends of the first substrate 81, which are used for electrical connection to a drive circuit for the ultrasonic device 80 included in the control unit 90.

[0055] Although not in Figure 6 As shown in the diagram, in this embodiment, multiple second electrodes 84 are electrically connected to each other at the ends of the first substrate 81. Furthermore, when the ultrasonic device 80 is controlled, a common voltage is applied to the multiple second electrodes 84. On the other hand, independent individual voltages are applied to the multiple first electrodes 82. Therefore, the first electrodes 82 are also referred to as individual electrodes, and the second electrodes 84 are also referred to as common electrodes. A piezoelectric element 83 is formed in the area where the first electrodes 82 and the second electrodes 84 overlap. The overlapping portion of the first electrodes 82, the piezoelectric element 83, and the second electrodes 84 is referred to as an ultrasonic transducer 8. The piezoelectric element 83 corresponding to the first ultrasonic transducer 8A is also referred to as a first piezoelectric element, and the piezoelectric element 83 corresponding to the second ultrasonic transducer 8B is also referred to as a second piezoelectric element.

[0056] Figure 7 yes Figure 6 Sectional view along line VII-VII. Figure 8 yes Figure 6 A sectional view along line VIII-VIII. (See example.) Figure 8As shown, the ultrasonic device 80, based on the above structure, further includes a vibrating plate 85, a second substrate 86, and multiple pillars 87. An opening 81a is formed in the first substrate 81. The vibrating plate 85 is disposed between the first substrate 81 and the first electrode 82. The second substrate 86 is disposed above the ultrasonic transducer 8 in a manner that covers the ultrasonic transducer 8.

[0057] In this embodiment, the first substrate 81 is a silicon substrate. In this embodiment, the vibrating plate 85 is a laminated film of silicon oxide film and zirconium oxide film. In this embodiment, as... Figure 6 As shown, when viewed from above along the Z direction, the vibrating plate 85 has an opening 81a formed on the first substrate 81 in such a way that it includes one ultrasonic transducer 8 in the Y direction and three ultrasonic transducers 8 in the X direction.

[0058] like Figure 7 as well as Figure 8 As shown, the opening 81a is defined by the wall portion 81b. (As indicated...) Figure 7 As shown, a wall portion 81b is formed between two adjacent ultrasonic transducers 8 in the Y direction. Additionally, as... Figure 8 As shown, for every three ultrasonic transducers 8 arranged side by side in the X direction, a wall portion 81b is formed between adjacent ultrasonic transducers 8.

[0059] In this embodiment, such as Figure 8 As shown, a pillar 87 is formed between two adjacent ultrasonic transducers 8 in the X direction. The pillar 87 is respectively joined to the vibrating plate 85 and the second substrate 86. In this embodiment, the pillar 87 is formed of photosensitive resin, also known as a permanent resist, which remains as a structural component after development. The second substrate 86 functions as a sealing substrate. A joint portion (not shown) protruding towards the first substrate 81 is formed on the outer edge of the second substrate 86. The second substrate 86 is joined to the first substrate 81 through the joint portion, thereby bonding the second substrate 86 to the first substrate 81.

[0060] By applying a voltage between the first electrode 82 and the second electrode 84, the piezoelectric element 83 deforms, causing the vibrating plate 85 to vibrate and emit ultrasonic waves. The vibration of the vibrating plate 85 is suppressed by the wall portion 81b and the column portion 87, respectively. The wall portion 81b and the column portion 87 function as fixed ends for vibration.

[0061] like Figure 7As shown, the first interval G1 is narrower than the second interval G2. The first interval G1 is the interval between two adjacent wall portions 81b in the Y direction that sandwich the first ultrasonic transducer 8A, and the second interval G2 is the interval between two adjacent wall portions 81b in the Y direction that sandwich the second ultrasonic transducer 8B. As described above, the two adjacent wall portions 81b function as fixed ends for vibration. Therefore, the resonant frequency of the ultrasonic transducer 8 changes according to the interval between the two wall portions 81b. In this embodiment, by making the first interval G1 narrower than the second interval G2, the resonant frequency of the first ultrasonic transducer 8A is configured to be higher than the resonant frequency of the second ultrasonic transducer 8B. As a result, the first ultrasonic transducer 8A can emit ultrasonic waves with a higher frequency than the ultrasonic waves emitted from the second ultrasonic transducer 8B.

[0062] Although Figure 8 The second interval G2 is not shown, but the first interval G1 is narrower than the second interval G2. The first interval G1 is the interval between two adjacent columns 87 in the X direction that sandwich the first ultrasonic transducer 8A, and the second interval G2 is the interval between two adjacent columns 87 in the Y direction that sandwich the second ultrasonic transducer 8B.

[0063] The two wall portions 81b adjacent to each other in the Y direction are also referred to as a pair of fixed portions. The two column portions 87 adjacent to each other in the X direction are also referred to as a pair of fixed portions. The pair of fixed portions function as fixed ends of vibration by fixing the vibrating plate 85, which vibrates according to the vibration of the corresponding piezoelectric element 83, to the substrate opposite to the vibrating plate 85, namely the first substrate 81 or the second substrate 86.

[0064] As described above, in this embodiment, the first electrode 82 is a separate electrode, and the second electrode 84 is a common electrode. Figure 6 As shown, the group of ultrasonic transducers 8 that share the same first electrode 82 is called "channel CH".

[0065] It should be noted that, in Figure 7 as well as Figure 8 The ultrasonic device 80 is shown in the diagram with the following configuration: the distance between the first substrate 81 and the acoustic lens 73 is shorter than the distance between the second substrate 86 and the acoustic lens 73. However, the configuration of the ultrasonic device 80 is not limited to this. Alternatively, the ultrasonic device 80 can be configured on the cover 71 in the following manner: the distance between the second substrate 86 and the acoustic lens 73 is shorter than the distance between the first substrate 81 and the acoustic lens 73, that is, with... Figure 7 as well as Figure 8 The configuration method of flipping vertically.

[0066] Figure 9 This is a three-dimensional diagram showing the relationship between channel CH and nozzle N. (Example) Figure 9As shown, multiple channels CH are arranged side-by-side in the Y direction, which is the first direction. The arrangement direction of the multiple channels CH is the same as the arrangement direction of the nozzles N. Therefore, by staggering the emission timing of the burst waves of ultrasonic waves emitted from the multiple channels CH, ultrasonic waves can be concentrated into the nozzle N of the object in the multiple nozzles N.

[0067] Figure 10 This is a waveform diagram of the burst signal Sigd applied to a single electrode. For example... Figure 10 As shown, the burst signal Sigd is a burst signal that repeats periodically with a period TD, consisting of a first period TD1 emitting a sine wave and a second period TD2 emitting a DC voltage. The sine wave in the first period TD1 is a sine wave with an amplitude of A, using the center voltage of the amplitude as the reference voltage Vs. The voltage in the second period TD2 is the reference voltage Vs. The first period TD1 is also referred to as the signal emission period.

[0068] The control unit 90 inputs a burst signal Sigd to the ultrasonic transducer 8 to control the ultrasonic device 80. By applying a reference voltage Vs to the second electrode 84 of the ultrasonic transducer 8 and inputting the burst signal Sigd to the first electrode 82 of the ultrasonic transducer 8, the ultrasonic transducer 8 emits a burst wave of ultrasound. It should be noted that a burst wave of ultrasound refers to an ultrasound wave that repeats with a period TD between the period of ultrasound emission and the period of ultrasound emission pause.

[0069] The control unit 90 inputs a burst signal Sigd of the waveform during the first period TD1 to the first ultrasonic transducer 8A. Therefore, if the first ultrasonic transducer 8A is input with the burst signal Sigd, the frequency of the emitted ultrasonic wave is the burst wave of the first frequency. The control unit 90 inputs a burst signal Sigd of the waveform during the first period TD1 to the second ultrasonic transducer 8B. Therefore, if the second ultrasonic transducer 8B is input with the burst signal Sigd, the frequency of the emitted ultrasonic wave is the burst wave of the second frequency.

[0070] Figure 11 This is a graph illustrating the relationship between the burst signal Sigd input to multiple channel CHs and the ultrasonic waves emitted from multiple channel CHs. Figure 11 The example illustrates the scenario where the target area Atg for focusing ultrasound waves is located above channel CH5 (channel 5). It should be noted that, for ease of understanding, the following explanation illustrates the scenario where nine channels CH1 through CH9 (channels 1 through 9) are controlled to focus ultrasound waves onto the target area Atg.

[0071] The control unit 90 controls the timing of ultrasonic wave emission from the ultrasonic transducer 8 to be staggered according to the distance between the target area Atg and the ultrasonic transducer 8. It should be noted that the distance between the target area Atg and the ultrasonic transducer 8 refers to the distance between the center of the target area Atg and the center of the ultrasonic transducer 8.

[0072] like Figure 11 As shown, the control unit 90 controls multiple ultrasonic transducers 8 in such a way that the emission timing of the burst waves is staggered according to the arrangement direction of the multiple channels CH, so that the emission timing of the burst wave emitted from channel CH5 is the latest among the multiple channels CH. Specifically, the control unit 90 sets the start time of the first period TD1 of each burst signal Sigd to be later in the order of channel CH1, channel CH2, channel CH3, channel CH4, and channel CH5, and earlier in the order of channel CH5, channel CH6, channel CH7, channel CH8, and channel CH9. As a result, the ultrasonic waves emitted from each channel CH overlap within the target range Atg, becoming large-amplitude ultrasonic waves. In this way, the control unit 90 controls the emission timing of the burst waves emitted by each of the multiple ultrasonic transducers 8 in such a way that it staggers according to a first direction, causing the ultrasonic waves to converge within the target range Atg.

[0073] Generally, when the diameter of the range of emitted ultrasonic waves is defined as the aperture D [m], the diameter of the range of ultrasonic wave convergence is defined as the beam diameter d [m], the distance from the range of emitted ultrasonic waves to the range of ultrasonic wave convergence is defined as the distance L [m], and the frequency of ultrasonic waves is defined as the frequency f [Hz], the beam diameter d is expressed by the following equation (1). It should be noted that in equation (1), "c" is the speed of sound [m / s].

[0074] d=(1.02×L×c) / (D×f) (1)

[0075] As shown in equation (1), the higher the frequency of the ultrasonic wave, the smaller the beam diameter d can be. In this embodiment, by setting the first frequency to 1 MHz or higher, the beam diameter d can be made smaller. In this embodiment, the diameter of the nozzle N is about 20 μm.

[0076] A4. Cleaning process: Figure 12 This is a flowchart illustrating the cleaning process. For example, when observing printed materials, a user of the liquid jet device 100 may instruct the device to clean via an interface (not shown) if the print quality is poor. If the control unit 90 receives the cleaning instruction, it performs the cleaning process.

[0077] exist Figure 12 In step S10, the control unit 90 assembles the cover 71 onto the liquid spray head 26 by moving the liquid spray head 26 to the position of the cleaning device 70 and moving the cover 71 so that the cover 71 is in close contact with the spray surface 62a.

[0078] In step S12, the control unit 90 stores liquid LQ in the recess 71a of the cover 71. In this embodiment, the control unit 90 fills the space surrounded by the spray surface 62a and the recess 71a with ink by spraying ink from the liquid spray head 26. It should be noted that, as another embodiment, the liquid LQ stored in the cover 71 may not be printing ink, but pure water or a cleaning liquid.

[0079] In step S14, the control unit 90 identifies a malfunctioning nozzle among the plurality of nozzles N that is not performing normal spraying. The malfunctioning spraying can occur in the following ways: the amount of ink sprayed is not predetermined by the control unit 90; the ink is not sprayed at the desired speed; or the ink falls off the medium 12 at a misaligned location when it does not follow the desired flight path.

[0080] In this embodiment, the control unit 90 determines the abnormal nozzle by detecting residual vibrations when ink is ejected in step S12 and comparing the detected residual vibrations with a predetermined reference vibration. Residual vibrations refer to the vibrations of the piezoelectric element 44 after a driving voltage for ejection is applied to the piezoelectric element 44 of the liquid ejection head 26.

[0081] In detail, at the upper electrode 443, a detection wiring for detecting residual vibration is electrically connected separately from the drive wiring for applying the drive voltage. The residual vibration is converted into voltage by the piezoelectric layer 442. Therefore, the control unit 90 detects the residual vibration by detecting the change in voltage of the detection wiring after the drive voltage is applied.

[0082] The residual vibration varies depending on the volume of the pressure chamber C, the weight of the ink, etc. Therefore, when the adhering material DE is attached to the inside of the nozzle N or the periphery of the nozzle N on the spray surface 62a, for example, the period of the residual vibration deviates from the period of the reference vibration. In this embodiment, the control unit 90 determines that the nozzle N is abnormal when the period of the residual vibration of the target nozzle N is outside the predetermined range of the reference period.

[0083] In step S16, the control unit 90 acquires the abnormal nozzle determined in step S14 as the attachment range where the adhering substance DE is attached. In step S18, the control unit 90 sets the target range Atg using the attachment range. Specifically, the control unit 90 sets the range including the abnormal nozzle and at least one of the areas surrounding the nozzle as the target range Atg, where the area surrounding the nozzle is the range on the spray surface 62a surrounding the abnormal nozzle. It should be noted that, as Figure 9 As shown, when the range including nozzle N is set as the object range Atg, when viewed from above from a direction perpendicular to nozzle plate 62, the object range Atg is set in such a way that it includes the range of nozzle N on the same plane as the spray surface 62a.

[0084] It should be noted that, for ease of understanding, Figure 9 The target range Atg shown indicates the range of the ultrasonic waves emitted by the ultrasonic transducer 8 after being further focused by the acoustic lens 73. In this embodiment, assuming the absence of the acoustic lens 73, the ultrasonic waves emitted from the ultrasonic device 80 do not converge in the X direction. Therefore, specifically, in step S18, the control unit 90 sets the position range in the Y direction on the jet surface 62a as the target range Atg.

[0085] exist Figure 12 In step S20, the control unit 90 causes the first ultrasonic wave to be emitted from the first ultrasonic transducer 8A included in the first channel CHA, such that the first ultrasonic wave is focused on the target area Atg. Specifically, the control unit 90 inputs a burst signal Sigd to the first ultrasonic transducer 8A, causing a burst wave to be emitted from the first ultrasonic transducer 8A. As described above, the burst signal Sigd input to each of the first ultrasonic transducers 8A in channels CH1 to CH9 is adjusted so that the emission time of the burst wave is staggered according to the first direction. After the ultrasonic wave emitted from the ultrasonic device 80 is transmitted within the acoustic lens 73, it is transmitted in the liquid LQ stored in the cover 71 and focused on the target area Atg. As a result, numerous tiny bubbles are generated near the target area Atg.

[0086] Figure 13 This is a diagram illustrating the method for removing the deposit DE in this application. In the method of this application, after emitting an ultrasonic wave of a first frequency in step S20, an ultrasonic wave of a second frequency is emitted in step S22, the second frequency being lower than the first frequency.

[0087] Generally speaking, the higher the frequency of the emitted ultrasound, the smaller the diameter of the bubbles produced by cavitation. Therefore, as... Figure 13As shown in "A", if a high-frequency first ultrasonic wave is focused on the target area Atg, numerous tiny bubbles will be generated near the target area Atg due to cavitation. These numerous bubbles are roughly generated in a semi-ellipsoidal area, also known as a cloud.

[0088] Next, as Figure 13 As shown by "B", if a low-frequency second ultrasonic wave is radiated onto the target area Atg, numerous bubbles are forced to vibrate. Thus, as... Figure 13 As shown by the "C", numerous bubbles eventually collapse, generating a shock wave.

[0089] If low-frequency ultrasonic waves are emitted into a cloud, the volume of the bubbles decreases. In particular, the collapse of numerous bubbles near the center of the cloud can be considered to create very high pressure in the surrounding area. Thus, by emitting a low-frequency second ultrasonic wave after emitting a high-frequency first ultrasonic wave, it is possible to generate high pressure caused by shock waves within the target area Atg.

[0090] exist Figure 12 In step S22, the control unit 90, within a predetermined time period starting from the end of the first ultrasonic wave emission, causes the second ultrasonic wave to be concentrated on the target area Atg, thereby emitting a second ultrasonic wave from the second ultrasonic transducer 8B included in the second channel CHB. Specifically, the control unit 90 inputs a burst signal Sigd to the second ultrasonic transducer 8B, emitting a burst wave from the second ultrasonic transducer 8B. As described above, numerous bubbles collapse, generating a shock wave. The high pressure caused by the shock wave and the acoustic radiation force of the ultrasonic wave remove the deposit DE from the nozzle plate 62. It should be noted that the predetermined time from the end of the first ultrasonic wave emission to the start of the second ultrasonic wave emission is, for example, about 1 microsecond to 100 microseconds.

[0091] Unlike this embodiment, when a continuous wave is emitted from the ultrasonic device 80, a standing wave of ultrasound is generated in the liquid LQ between the ultrasonic device 80 and the spray surface 62a. Although the sound pressure at the antinodes of the standing wave is high, the sound pressure at the nodes is low. Therefore, in the liquid LQ as a whole, areas where cavitation is prone to occur and areas where cavitation is difficult to occur are generated, which can easily lead to uneven cleaning. In this embodiment, since ultrasound is selectively focused towards the target area Atg, numerous tiny bubbles are generated near the target area Atg, and a second ultrasound is emitted, causing the numerous tiny bubbles to collapse and generate shock waves, thereby efficiently cleaning the areas with attached deposits DE.

[0092] In this embodiment, the plurality of first ultrasonic transducers 8A are closely arranged in the Y direction. Therefore, compared with the case where the plurality of first ultrasonic transducers 8A are loosely arranged, the sound pressure of the first ultrasonic wave emitted toward the target range Atg can be increased.

[0093] It should be noted that in step S22 of this embodiment, the second ultrasonic wave is focused on the target area Atg. In other embodiments, the second ultrasonic wave may not be focused on the target area Atg. Specifically, in step S22, the control unit 90 may, for example, control the simultaneous emission of ultrasonic waves from all the second ultrasonic transducers 8B.

[0094] In step S24, the control unit 90 checks whether the spraying abnormality of the abnormal nozzle has been eliminated. In this embodiment, after temporarily moving the cover 71 to the release position, the control unit 90 performs the check using residual vibration when ink is sprayed from the nozzle N, similar to step S14.

[0095] In step S26, the control unit 90 determines whether the jetting abnormality of the abnormal nozzle has been eliminated. If, in step S26, the control unit 90 determines that the jetting abnormality of the abnormal nozzle has not been eliminated, in step S28, the control unit 90 moves the cover 71 to the assembly position. In step S30, similarly to step S20, the control unit 90 emits the first ultrasonic wave from the ultrasonic device 80 in a manner that focuses the first ultrasonic wave onto the target area Atg. It should be noted that, in step S28, after the cover 71 is assembled, ink can also be sprayed from the liquid spray head 26 to fill the space surrounded by the spray surface 62a and the recess 71a with ink.

[0096] In step S32, the control unit 90, similar to step S22, causes the second ultrasonic wave to be emitted from the ultrasonic device 80 in such a way that the second ultrasonic wave is focused on the target range Atg.

[0097] After performing step S32, the control unit 90 returns to step S24 to confirm whether the jetting abnormality of the abnormal nozzle has been eliminated. In step S26, if it is determined that the jetting abnormality of the abnormal nozzle has been eliminated, in step S34, the control unit 90 moves the cover 71 to the release position and removes the cover 71, using a drainage flow path (not shown) to drain the liquid LQ stored in the recess 71a of the cover 71, thus ending the processing flow.

[0098] According to the first embodiment described above, the cleaning apparatus 70 includes a cover 71, an ultrasonic device 80, and a control unit 90. The ultrasonic device 80 has a plurality of first ultrasonic transducers 8A and a plurality of second ultrasonic transducers 8B. The plurality of first ultrasonic transducers 8A emit first ultrasonic waves, and the plurality of second ultrasonic transducers 8B emit second ultrasonic waves at a second frequency, which is lower than the first frequency. After the control unit 90 emits the first ultrasonic waves in step S20, it emits the second ultrasonic waves in step S22. Due to the cavitation phenomenon caused by the emission of the first ultrasonic waves, numerous tiny bubbles are generated in the liquid LQ near the target area Atg. Subsequently, by emitting the second ultrasonic waves, the numerous bubbles collapse, generating shock waves and instantaneously generating high pressure. In this way, high pressure can be generated efficiently, thus improving the removal force of the deposits DE adhering to the spray surface 62a. Compared to the case of emitting ultrasonic waves of a single frequency, the cleaning efficiency can be improved.

[0099] Furthermore, in step S16, the control unit 90 sets a portion of the area including the spray surface 62a and the plurality of nozzles N, i.e., the area including the abnormal nozzles, as the target area Atg. Then, in step S20, the control unit 90 controls the ultrasonic device 80 to focus the first ultrasonic wave onto the target area Atg. As a result, numerous tiny bubbles can be selectively generated near the target area Atg. This allows for the efficient removal of the deposited material DE.

[0100] Furthermore, the cleaning apparatus 70 includes a vibrating plate 85, a plurality of piezoelectric elements 83, and a first substrate 81, which is configured to face the vibrating plate 85. The first interval G1 of a pair of wall portions 81b corresponding to the first ultrasonic transducer 8A is formed to be narrower than the second interval G2 of a pair of wall portions 81b corresponding to the second ultrasonic transducer 8B. Similarly, the first interval G1 of a pair of pillar portions 87 corresponding to the first ultrasonic transducer 8A is formed to be narrower than the second interval G2 of a pair of pillar portions 87 corresponding to the second ultrasonic transducer 8B. Thus, the resonant frequency of the first ultrasonic transducer 8A is configured to be higher than the resonant frequency of the second ultrasonic transducer 8B. In this way, by changing the patterns of the wall portions 81b and the pillar portions 87, it is easy to fabricate first ultrasonic transducers 8A and second ultrasonic transducers 8B that emit ultrasonic waves of different frequencies on the same first substrate 81.

[0101] B. Second implementation method: In the ultrasonic device 80 of the second embodiment, the configuration of the ultrasonic device 80, the first ultrasonic transducer 8A, and the second ultrasonic transducer 8B of the first embodiment differs. The differences from the first embodiment will be described, and other descriptions will be omitted. Furthermore, structures and processing steps identical to those in the first embodiment will be labeled with the same reference numerals, and detailed descriptions will be appropriately omitted.

[0102] Figure 14 This is a top view showing the overall structure of the ultrasonic device 80 according to this embodiment. In this embodiment, a first channel CHA is formed with a plurality of first ultrasonic transducers 8A arranged side by side in the X direction, and a second channel CHB is formed with a plurality of second ultrasonic transducers 8B arranged side by side in the X direction.

[0103] In this embodiment, the first channel CHA and the second channel CHB are arranged alternately in the Y direction. This allows the first ultrasonic wave with a higher sound pressure level to be focused onto the target area Atg, covering the entire area of ​​the plurality of nozzles N. In the ultrasonic device 80 of the first embodiment, the first ultrasonic transducer 8A is arranged closely in the Y direction. Therefore, the sound pressure of the ultrasonic wave emitted towards the nozzle plate 62 portion above the first ultrasonic transducer 8A in the first embodiment can be increased. On the other hand, the sound pressure of the first ultrasonic wave emitted towards the portion of the nozzle plate 62 away from the first ultrasonic transducer 8A is lower than the sound pressure of the ultrasonic wave emitted towards the nozzle plate 62 portion above the first ultrasonic transducer 8A. In this respect, the ultrasonic device 80 of this embodiment, viewed from above, has the first channel CHA arranged covering the entire area of ​​the nozzle plate 62. This allows the longest distance between the first ultrasonic transducer 8A and the nozzle N to be shorter than the longest distance between the first ultrasonic transducer 8A and the nozzle N in the first embodiment. Therefore, the first ultrasonic wave with a higher sound pressure level can be emitted across the entire area of ​​the plurality of nozzles N.

[0104] According to the second embodiment described above, the first channel CHA and the second channel CHB are arranged alternately in the Y direction. This allows for the emission of a first ultrasonic wave with a high sound pressure throughout the entire area of ​​the plurality of nozzles N.

[0105] C. Third implementation method: In the ultrasonic device 80 of the third embodiment, the configuration of the ultrasonic device 80, the first ultrasonic transducer 8A, and the second ultrasonic transducer 8B of the first embodiment is different. The differences from the first embodiment will be described, and other descriptions will be omitted. Furthermore, structures and processing steps identical to those in the first embodiment will be labeled with the same reference numerals, and detailed descriptions will be appropriately omitted.

[0106] Figure 15 This is a top view showing the overall structure of the ultrasonic device 80 of this embodiment. The ultrasonic device 80 of the first embodiment described above has a structure in which groups of independently controllable ultrasonic transducers 8, i.e., channels CH, are arranged side-by-side in only one direction. In contrast, the channels CH of this embodiment are arranged in a matrix. In this embodiment, the ultrasonic device 80 does not include an acoustic lens 73.

[0107] like Figure 15As shown, the ultrasonic device 80 of this embodiment includes a plurality of ultrasonic transducer arrays DC, in which first ultrasonic transducers 8A and second ultrasonic transducers 8B are alternately arranged side by side in the Y direction, which is a first direction. The ultrasonic transducer arrays DC are arranged side by side in the X direction, which is a second direction, intersecting the first direction, but not intersecting the jet surface 62a at a right angle.

[0108] In this embodiment, a channel CH is configured to include an ultrasonic transducer 8. In the first embodiment, a channel CH is formed by interconnecting a plurality of second electrodes 84. In contrast, in this embodiment, the second electrodes 84 are not interconnected, but are configured to be independently controllable.

[0109] The control unit 90 synchronizes the emission timing of the ultrasonic transducers 8 arranged in parallel in the first direction with the emission timing of the ultrasonic transducers 8 arranged in parallel in the second direction, thereby concentrating the ultrasonic waves on the target area Atg.

[0110] Typically, the control unit 90 controls the ultrasonic transducer 8 in a manner that ensures the emission timing is the same as that of the ultrasonic transducer 8 at a distance equal to that of the target range Atg. Therefore, in addition to the direction in which the nozzles N are arranged on the jet surface 62a, the target range Atg can also be set at a desired position for directions intersecting the direction of the nozzles N arrangement.

[0111] According to the third embodiment described above, a plurality of ultrasonic transducer arrays DC, in which the first ultrasonic transducer 8A and the second ultrasonic transducer 8B are alternately arranged side by side, are arranged side by side in the X direction. The first ultrasonic transducer 8A and the second ultrasonic transducer 8B can be controlled independently. Therefore, in addition to the Y direction, ultrasonic waves can be concentrated at any position in the X direction.

[0112] D. Fourth Implementation Method: The ultrasonic device 80 of the fourth embodiment differs in construction from that of the ultrasonic device 80 of the first embodiment. The differences from the first embodiment will be described, and other descriptions will be omitted. Furthermore, structures and processing steps identical to those in the first embodiment will be labeled with the same reference numerals, and detailed descriptions will be appropriately omitted.

[0113] Figure 16 This is a top view showing the detailed structure of the ultrasonic device 80 according to the fourth embodiment. Figure 17 yes Figure 16 A cross-sectional view along line XVII-XVII. The opening 81a formed on the first substrate 81 in the first embodiment is formed such that it includes one ultrasonic transducer 8 in the Y direction and three ultrasonic transducers 8 in the X direction. In contrast, the opening 81a in this embodiment is as follows: Figure 16As shown, it is formed in the following manner: it includes four ultrasonic transducers 8 in the Y direction and three ultrasonic transducers 8 in the X direction.

[0114] like Figure 17 As shown, a column portion 87 is formed between two adjacent ultrasonic transducers 8 in the Y direction. A first gap G1 is narrower than a second gap G2. The first gap G1 is the gap between two adjacent column portions 87 in the Y direction, sandwiching the first ultrasonic transducer 8A, and the second gap G2 is the gap between two adjacent column portions 87 in the Y direction, sandwiching the second ultrasonic transducer 8B. Therefore, the first ultrasonic transducer 8A can emit ultrasonic waves with a higher frequency than the ultrasonic waves emitted from the second ultrasonic transducer 8B.

[0115] In the first embodiment described above, a wall portion 81b is used as the fixed end for vibration of the vibrating plate 85 in the Y direction. In this respect, as in this embodiment, a pillar portion 87 can also be used as the fixed end for vibration of the vibrating plate 85. When the opening portion 81a is formed by etching in semiconductor manufacturing processes, if the opening area of ​​the opening portion 81a is small, it becomes difficult to control the etching. In this respect, according to this embodiment, by setting the opening area of ​​the opening portion 81a to be large, the opening portion 81a can be formed with good precision through etching. Furthermore, in this case, a pillar portion 87 can also be used to form the fixed end for vibration. Moreover, in this embodiment, since a permanent resist is used in the pillar portion 87, it is easier to form the pillar portion 87 that functions as the fixed end for vibration.

[0116] E. Other implementation methods: (E1) In the first embodiment described above, the control unit 90 controls the focusing of the first ultrasonic wave onto the target area Atg. In other embodiments, the control unit 90 may not focus the first ultrasonic wave onto the target area Atg. Specifically, for example, the control unit 90 may control the emission of the first ultrasonic wave from multiple first ultrasonic transducers 8A without synchronizing the emission timing of the first ultrasonic wave. Even without focusing the first ultrasonic wave onto the target area Atg, a high pressure can be instantaneously generated by emitting a second ultrasonic wave after the first ultrasonic wave is emitted, thus improving the removal force.

[0117] (E2) In the first embodiment described above, the waveform of the first period TD1 of the burst signal Sigd is a sine wave, but the waveform is not limited to a sine wave. For example, the waveform of the first period TD1 of the burst signal Sigd can also be a rectangular wave.

[0118] (E3) In the first embodiment described above, in order to concentrate ultrasonic waves into the target area Atg, the multiple ultrasonic transducers 8 are controlled in such a way that the emission timings are staggered according to the first direction. As another embodiment, for example, at least two ultrasonic transducers 8 may be controlled in such a way that the emission timings of at least two of the multiple ultrasonic transducers 8 are staggered from each other. Specifically, for example, the same burst signal Sigd may be input to two adjacent ultrasonic transducers 8. By controlling at least two of the multiple ultrasonic transducers 8 in such a way that the emission timings of the burst waves are staggered from each other, ultrasonic waves can be concentrated into the target area Atg.

[0119] (E4) In the first embodiment described above, the control unit 90 determines the abnormal nozzle and obtains the adhesion range as the determined abnormal nozzle. In the first embodiment described above, residual vibration after ink spraying is used to determine the abnormal nozzle. As another embodiment for determining the abnormal nozzle, the control unit 90 may also use an image obtained by photographing the printed material with a camera to determine the abnormal nozzle. In addition, for example, if the adhesion position of the adhesive DE can be determined using an image of the printed material, the control unit 90 may obtain the adhesion position as the adhesion range instead of the abnormal nozzle. In addition, the control unit 90 may also obtain the adhesion position of the adhesive DE determined by photographing the nozzle plate 62 with a camera as the adhesion range. In addition, for example, if the position where the adhesive DE is likely to adhere can be statistically determined based on the position of the nozzle plate 62, the control unit 90 may also obtain that position as the adhesion range. Specifically, for example, the adhesion range may be pre-stored in the storage circuit of the control unit 90, and the control unit 90 may obtain the adhesion range by referring to the storage circuit.

[0120] (E5) In the first embodiment described above, in step S18, the control unit 90 as follows: Figure 9 As shown, the range including nozzle N is set as the object range Atg. In the event of a jetting abnormality, the deposit DE may not necessarily be attached inside the nozzle N of the abnormal nozzle. For example, there may be cases where the deposit DE is attached around the nozzle of the abnormal nozzle. Therefore, as another implementation, steps S20 and S22 after changing the object range Atg may be performed multiple times, focusing the ultrasonic waves on the range including nozzle N and the area around the nozzle excluding nozzle N.

[0121] (E6) In the first embodiment described above, liquid LQ ejected from nozzle N is stored in the recess 71a of cover 71. Alternatively, the recess 71a may have a supply path through which liquid LQ is supplied. Furthermore, in the first embodiment described above, the cleaning apparatus 70 includes an acoustic lens 73, but it may not. Without the acoustic lens 73, at least the ultrasonic waves can be focused in the alignment direction of the channel CH. Additionally, in the fourth embodiment described above, the cleaning apparatus 70 does not include the acoustic lens 73, but it may also include it.

[0122] (E7) In the first embodiment described above, the frequency of the first ultrasonic wave is approximately 1 MHz or more and about 10 MHz or less. Furthermore, the frequency of the second ultrasonic wave is approximately 100 kHz or more and about 1 MHz less. Alternatively, the frequency of the first ultrasonic wave may be approximately 1 MHz or more and about 10 MHz or less, and the frequency of the second ultrasonic wave may be even lower than the frequency of the first ultrasonic wave. For example, the lower limit of the frequency of the first ultrasonic wave may be approximately 10 kHz.

[0123] (E8) In the second embodiment described above, the first ultrasonic transducer 8A and the second ultrasonic transducer 8B are arranged alternately in the Y direction. Alternatively, the first ultrasonic transducer 8A and the second ultrasonic transducer 8B may be arranged alternately every few units in the Y direction. In the fourth embodiment described above, the plurality of ultrasonic transducer columns DC are configured such that the positions of the ultrasonic transducers 8 in the Y direction are consistent with each other. Alternatively, the positions of the ultrasonic transducers 8 in the Y direction may be configured to be staggered, i.e., an alternating arrangement. Furthermore, as another embodiment, the first ultrasonic transducer 8A and the second ultrasonic transducer 8B may be arranged alternately in the X direction.

[0124] (E9) In the first embodiment described above, the lower electrode of the piezoelectric element 83 is a separate electrode, and the upper electrode of the piezoelectric element 83 is a common electrode. In other embodiments, the lower electrode of the piezoelectric element 83 may be a common electrode, and the upper electrode of the piezoelectric element 83 may be a separate electrode.

[0125] F. Other methods: This disclosure is not limited to the embodiments described above, and can be implemented in various ways without departing from its spirit. For example, this disclosure can also be implemented in the following ways. In order to solve part or all of the technical problems of this disclosure, or to achieve part or all of the effects of this disclosure, the technical features in the above embodiments corresponding to the technical features in the various methods described below can be appropriately replaced or combined. In addition, if a technical feature is not described as an essential technical feature in this specification, it can be appropriately deleted.

[0126] (1) According to a first aspect of this disclosure, a cleaning apparatus is provided for cleaning a nozzle plate having a spray surface and forming a plurality of nozzles for spraying liquid. The cleaning apparatus comprises: a cover configured to face the spray surface and having a recess, the cover being capable of storing liquid in a space surrounded by the recess and the spray surface; an ultrasonic device disposed on the cover, the ultrasonic device emitting ultrasonic waves toward the spray surface; and a control unit, the ultrasonic device having a plurality of first ultrasonic transducers and a plurality of second ultrasonic transducers, the plurality of first ultrasonic transducers emitting first ultrasonic waves of a first frequency, the plurality of second ultrasonic transducers emitting second ultrasonic waves of a second frequency lower than the first frequency, and the control unit, while the space is filled with liquid, emitting the first ultrasonic waves by the ultrasonic device, and then emitting the second ultrasonic waves. According to this method, while the space surrounded by the recess and the spray surface is filled with liquid, numerous bubbles are generated in the liquid due to cavitation caused by the emission of the first ultrasonic waves. Subsequently, by emitting a second ultrasonic wave, numerous bubbles collapse, generating high pressure. This efficient generation of high pressure enhances the removal of deposits.

[0127] (2) In the above-described manner, the control unit may also define a portion of the range including the jet surface and the plurality of nozzles as the target range, and when the ultrasonic device emits the first ultrasonic wave, the control unit controls the ultrasonic device to concentrate the first ultrasonic wave onto the target range. According to this method, ultrasonic waves can be selectively concentrated onto the target range.

[0128] (3) In the above method, the control unit may also identify an abnormal nozzle among the plurality of nozzles, the abnormal nozzle being a nozzle exhibiting a jetting abnormality, and the control unit may set the target range as a range including the abnormal nozzle and at least one of the surrounding areas, where the surrounding area is the range on the jetting surface surrounding the abnormal nozzle. According to this method, ultrasonic waves can be selectively focused onto the deposit that has generated a jetting abnormality.

[0129] (4) In the above method, the control unit may input a burst signal with the frequency of the first frequency during the signal transmission period to the plurality of first ultrasonic transducers. If the burst signal is input to each of the plurality of first ultrasonic transducers, the burst wave of the first ultrasonic wave with the frequency of the first frequency during the ultrasonic wave transmission period will be emitted. In order to concentrate the first ultrasonic wave within the target area, the control unit controls the first ultrasonic transducer that inputs the burst signal among the plurality of first ultrasonic transducers, so that the emission timing of the burst wave is staggered according to the distance between the target area and each of the first ultrasonic transducers.

[0130] (5) In the above manner, the plurality of first ultrasonic transducers and the plurality of second ultrasonic transducers may also be arranged in a first direction.

[0131] (6) In the above-described manner, the first ultrasonic transducers of the plurality of first ultrasonic transducers and the second ultrasonic transducers of the plurality of second ultrasonic transducers may be arranged alternately in the first direction. According to this manner, ultrasonic waves with higher sound pressure can be emitted throughout the entire area of ​​the nozzle plate.

[0132] (7) In the above-described manner, the cleaning device may also include multiple ultrasonic transducer columns, in which each first ultrasonic transducer and each second ultrasonic transducer are arranged alternately in the first direction, and the multiple ultrasonic transducer columns are arranged side by side in the second direction, which intersects the first direction and does not intersect the spray surface at a right angle.

[0133] (8) In the above-described manner, the cleaning apparatus may also include: a vibrating plate; a plurality of piezoelectric elements formed on the vibrating plate; a substrate configured to face the vibrating plate; and a pair of fixing portions corresponding to each of the plurality of piezoelectric elements and fixing the vibrating plate to the substrate. The plurality of first ultrasonic transducers and the plurality of second ultrasonic transducers are arranged in a first direction. When the vibrating plate is viewed in a direction perpendicular to the vibrating plate, each piezoelectric element is disposed between the pair of fixing portions. The plurality of piezoelectric elements includes first piezoelectric elements and second piezoelectric elements. The first piezoelectric element corresponds to each of the first ultrasonic transducers of the plurality of first ultrasonic transducers, and the second piezoelectric element corresponds to each of the second ultrasonic transducers of the plurality of second ultrasonic transducers. The spacing between the pair of fixing portions corresponding to the first piezoelectric element in the first direction is narrower than the spacing between the pair of fixing portions corresponding to the second piezoelectric element in the first direction. According to this method, by adjusting the spacing of the pair of fixing portions, first ultrasonic transducers and second ultrasonic transducers having different resonant frequencies can be easily fabricated on the same substrate.

[0134] This disclosure can also be implemented in various ways other than by a cleaning apparatus. For example, it can be implemented by a cleaning method using a nozzle plate, a computer program that implements the cleaning method, or a non-transitory recording medium that records the computer program.

Claims

1. A cleaning device, characterized in that, The cleaning device is used to clean a nozzle plate, the nozzle plate having a spray surface and forming a plurality of nozzles for spraying liquid, and the cleaning device comprises: A cover, configured to face the spray surface and having a recess, the cover being able to store liquid in the space surrounded by the recess and the spray surface; An ultrasonic device is disposed on the cover, and the ultrasonic device radiates ultrasonic waves toward the jetting surface; as well as Control Department The ultrasonic device has multiple first ultrasonic transducers and multiple second ultrasonic transducers. The multiple first ultrasonic transducers emit first ultrasonic waves at a first frequency, and the multiple second ultrasonic transducers emit second ultrasonic waves at a second frequency, which is lower than the first frequency. When the liquid is stored in the space, the control unit, after emitting the first ultrasonic wave, causes the ultrasonic device to emit the second ultrasonic wave.

2. The cleaning device according to claim 1, characterized in that, The control unit defines a portion of the range including the injection surface and the plurality of nozzles as the target range. When the ultrasonic device emits the first ultrasonic wave, the control unit controls the ultrasonic device to focus the first ultrasonic wave onto the target area.

3. The cleaning device according to claim 2, characterized in that, The control unit identifies an abnormal nozzle among the plurality of nozzles; the abnormal nozzle is one that exhibits jetting abnormalities. The control unit defines the target range as the range including the abnormal nozzle and at least one of the areas surrounding the nozzle, wherein the area surrounding the nozzle is the range on the spray surface that surrounds the abnormal nozzle.

4. The cleaning device according to claim 3, characterized in that, The control unit sends burst signals at a frequency of the first frequency to the plurality of first ultrasonic transducers. If the burst signal is input to each of the plurality of first ultrasonic transducers, the burst wave of the first ultrasonic wave emitted during the period of ultrasonic wave emission is at the first frequency. In order to concentrate the first ultrasonic wave onto the target area, the control unit controls the first ultrasonic transducer that inputs the burst signal among the plurality of first ultrasonic transducers, so that the timing of the emission of the burst wave is staggered according to the distance between the target area and each of the first ultrasonic transducers.

5. The cleaning device according to claim 1, characterized in that, The plurality of first ultrasonic transducers and the plurality of second ultrasonic transducers are arranged in a first direction.

6. The cleaning apparatus according to claim 5, characterized in that, The first ultrasonic transducers of the plurality of first ultrasonic transducers and the second ultrasonic transducers of the plurality of second ultrasonic transducers are arranged alternately in the first direction.

7. The cleaning apparatus according to claim 5, characterized in that, The cleaning device includes multiple rows of ultrasonic transducers, in which the first ultrasonic transducers and the second ultrasonic transducers are arranged alternately in the first direction. The plurality of ultrasonic transducers are arranged side by side in a second direction, which intersects the first direction but does not intersect the jet surface at a right angle.

8. The cleaning apparatus according to claim 1, characterized in that, The cleaning device includes: Vibrating plate; Multiple piezoelectric elements are formed on the vibrating plate; A substrate, configured to face the vibrating plate; and A pair of fixing parts, corresponding to each of the plurality of piezoelectric elements, fix the vibrating plate to the substrate. The plurality of first ultrasonic transducers and the plurality of second ultrasonic transducers are arranged in a first direction. When the vibrating plate is viewed in a direction perpendicular to it, the piezoelectric elements are arranged between the pair of fixed portions. The plurality of piezoelectric elements includes a first piezoelectric element and a second piezoelectric element, wherein the first piezoelectric element corresponds to each of the first ultrasonic transducers of the plurality of first ultrasonic transducers, and the second piezoelectric element corresponds to each of the second ultrasonic transducers of the plurality of second ultrasonic transducers. The spacing between the pair of fixing portions corresponding to the first piezoelectric element in the first direction is narrower than the spacing between the pair of fixing portions corresponding to the second piezoelectric element in the first direction.

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