Liquid dispensing device and head unit

Abstract

The present invention provides a liquid ejection device and a head unit capable of improving the accuracy of printhead temperature detection. [Solution] In a liquid ejection device and a head unit, a temperature information output circuit 26 that acquires head temperature signals TC1 to TCn according to the temperature of the print head includes a control circuit 500 that acquires digital temperature information dtc according to the temperature of the print head from the head temperature signals TC1 to TCn, and a timing control circuit 590 that controls the timing at which the control circuit 500 acquires the digital temperature information dtc. The timing control circuit 590 outputs a timing control signal Tgi that controls the control circuit 500 to acquire the digital temperature information dtc when the voltage value of the drive signal COM is within a predetermined range for a predetermined time or longer.

Description

Technical Field

[0001] The present invention relates to a liquid ejection device and a head unit.

Background Art

[0002] A liquid ejection device having a configuration including a piezoelectric element, a pressure chamber, and a nozzle communicating with the pressure chamber is known. Then, the print head ejects the liquid supplied to the pressure chamber from the nozzle by changing the volume of the pressure chamber by driving the piezoelectric element. In such a liquid ejection device provided with a print head, a technique for realizing ejection control suitable for the temperature of the ink by driving and controlling the piezoelectric element based on the temperature of the ink stored in the print head is known.

[0003] For example, Patent Document 1 discloses a technique for detecting the temperature of a print head by a temperature detection unit provided inside the print head and controlling the driving of the piezoelectric element based on the detected temperature of the print head.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the technique described in Patent Document 1, there is room for improvement in terms of accurately detecting the temperature of the print head.

Means for Solving the Problems

[0006] The liquid ejection device comprises a drive circuit that outputs a drive signal, a print head that ejects liquid in response to the drive signal, and a temperature information output circuit that acquires a head temperature signal corresponding to the temperature of the print head. The temperature information output circuit includes a temperature information acquisition circuit that acquires temperature information corresponding to the temperature of the print head from the head temperature signal, and a timing control circuit that controls the timing at which the temperature information acquisition circuit acquires the temperature information. The timing control circuit outputs a timing control signal that controls the temperature information acquisition circuit to acquire the temperature information when the voltage value of the drive signal is within a predetermined range for a predetermined time or longer.

[0007] The head unit comprises a print head that receives a drive signal and ejects liquid, and a temperature information output circuit that acquires a head temperature signal corresponding to the temperature of the print head. The temperature information output circuit includes a temperature information acquisition circuit that acquires temperature information corresponding to the temperature of the print head from the head temperature signal, and a timing control circuit that controls the timing at which the temperature information acquisition circuit acquires the temperature information. The timing control circuit outputs a timing control signal that controls the temperature information acquisition circuit to acquire the temperature information when the voltage value of the drive signal is within a predetermined range for a predetermined time or longer. [Brief explanation of the drawing]

[0008] [Figure 1] This is a diagram showing the schematic configuration of a liquid dispensing device. [Figure 2] This is an exploded perspective view showing the structure of the printhead. [Figure 3] This is a plan view of the print head as seen along the Z-axis. [Figure 4] Figure 3 shows a cross-sectional view of the print head in section Aa. [Figure 5] This is a detailed view of the main parts, showing the details of the main parts of Figure 4. [Figure 6] Figure 3 shows a cross-sectional view of the print head at the Bb section. [Figure 7]It is a diagram showing the functional configuration of a liquid ejection device. [Figure 8] It is a diagram showing an example of the signal waveform of a drive signal. [Figure 9] It is a diagram showing the configuration of a drive signal selection circuit. [Figure 10] It is a diagram showing an example of the decoding content in a decoder. [Figure 11] It is a diagram showing the configuration of a selection circuit. [Figure 12] It is a diagram for explaining the operation of a drive signal selection circuit. [Figure 13] It is a diagram showing an example of the configuration of a temperature detection circuit. [Figure 14] It is a diagram showing an example of the configuration of a temperature information output circuit. [Figure 15] It is a diagram showing an example of the configuration of a comparison circuit and a timing control circuit. [Figure 16] It is a diagram showing an example of the operation of a liquid ejection device. [Figure 17] It is a diagram showing an example of the operation of a temperature information output circuit. [Figure 18] It is a diagram showing an example of the waveform of a drive signal. [Figure 19] It is a diagram showing an example of the timing between a drive signal and a clock signal. [Figure 20] It is a diagram showing an example of the timing between a drive signal and a clock signal. [Figure 21] It is a diagram showing an example of the timing between a drive signal and a clock signal. [Figure 22] It is a diagram showing the functional configuration of the liquid ejection device of the second embodiment. [Figure 23] It is a diagram showing an example of the configuration of the temperature information output circuit in the second embodiment. [Figure 24] It is a diagram showing an example of the configuration of the comparison circuit and the timing control circuit in the second embodiment. [Figure 25] It is a diagram showing an example of the waveform of the drive signal in the second embodiment. [Figure 26] It is a diagram showing an example of the operation of the temperature information output circuit in the second embodiment.

Best Mode for Carrying Out the Invention

[0009] Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. The drawings used are for convenience of explanation. Note that the embodiments described below do not unduly limit the content of the present invention described in the claims. Also, not all of the configurations described below are essential constituent elements of the present invention.

[0010] 1. First Embodiment 1-1. Schematic Configuration of Liquid Discharge Device FIG. 1 is a diagram showing a schematic configuration of a liquid discharge device 1. In the liquid discharge device 1 of the present embodiment, a carriage 21 equipped with a print head 22 for discharging ink as an example of a liquid reciprocates along a scanning axis, and discharges ink onto a medium P conveyed along a conveyance direction, thereby forming a desired image on the medium P. It is a so-called serial printing type inkjet printer. Also, as the medium P in the liquid discharge device 1, any printing target such as printing paper, resin film, cloth, etc. can be used. Note that the liquid discharge device 1 is not limited to a serial printing type inkjet printer, and may be a line printing type inkjet printer. Also, the liquid discharge device 1 is not limited to an inkjet printer, and may be a color material discharge device used for manufacturing color filters such as liquid crystal displays, an electrode material discharge device used for forming electrodes such as organic EL displays and FEDs (surface emission displays), a biological organic matter discharge device used for manufacturing biochips, a three-dimensional modeling device, and a resist printing device, etc.

[0011] Here, in the following description, the explanation will be made using three spatial axes X, Y, and Z that are orthogonal to each other. Also, in the following description, when specifying the direction along each of the X-axis, Y-axis, and Z-axis, the tip side of the arrow indicating the direction along the illustrated X-axis is referred to as the +X side, and the starting side is referred to as the -X side. The tip side of the arrow indicating the direction along the illustrated Y-axis is referred to as the +Y side, and the starting side is referred to as the -Y side. The tip side of the arrow indicating the direction along the illustrated Z-axis is referred to as the +Z side, and the starting side is referred to as the -Z side.

[0012] As shown in Figure 1, the liquid dispensing device 1 comprises a control unit 10, a head unit 20, a moving unit 30, a transport unit 40, and an ink container 90.

[0013] The ink container 90 stores multiple types of ink that are dispensed onto the medium P. Such an ink container 90 can include an ink cartridge, a bag-shaped ink pack made of a flexible film, and an ink tank that allows for ink replenishment.

[0014] The control unit 10 includes processing circuits such as a CPU (Central Processing Unit) and an FPGA (Field Programmable Gate Array), as well as storage circuits such as semiconductor memory, and controls each element of the liquid dispensing device 1, including the head unit 20.

[0015] The head unit 20 includes a carriage 21 and a plurality of print heads 22. The carriage 21 is fixed to an endless belt 32 included in a moving unit 30, which will be described later. The plurality of print heads 22 are mounted on the carriage 21. Each of the plurality of print heads 22 receives a control signal Ctrl-H and a drive signal COM output by the control unit 10. Furthermore, ink stored in an ink container 90 is supplied to each of the plurality of print heads 22 via a tube or the like (not shown). The print heads 22 eject ink supplied from the ink container 90 based on the input control signal Ctrl-H and drive signal COM. At this time, the direction along the Z axis in which the print head 22 ejects ink, from the -Z side to the +Z side along the Z axis, is sometimes referred to as the ejection direction.

[0016] The moving unit 30 includes a carriage motor 31 and an endless belt 32. The carriage motor 31 operates based on a control signal Ctrl-C input from the control unit 10. The endless belt 32 extends along the X-axis and rotates in accordance with the operation of the carriage motor 31. This causes the carriage 21, which is fixed to the endless belt 32, to move along the X-axis. In other words, the moving unit 30 causes the multiple print heads 22 mounted on the carriage 21 to reciprocate along the X-axis. Hereinafter, in the following description, the direction along the X-axis in which the multiple print heads 22 mounted on the carriage 21 move may be referred to as the scanning direction.

[0017] The transport unit 40 includes a transport motor 41 and transport rollers 42. The transport motor 41 operates based on a control signal Ctrl-T input from the control unit 10. The transport rollers 42 rotate in accordance with the operation of the transport motor 41 while gripping the medium P. As a result, the medium P gripped by the transport rollers 42 is transported along the Y axis from the -Y side to the +Y side. In other words, the transport unit 40 transports the medium P along the Y axis from the -Y side to the +Y side. Here, in the following description, the direction in which the medium P is transported from the -Y side to the +Y side may be referred to as the transport direction.

[0018] In the liquid ejection device 1 configured as described above, the moving unit 30 controls the reciprocating motion of the carriage 21 along the scanning direction, and the transport unit 40 controls the transport of the medium P along the transport direction. The print head 22 mounted on the carriage 21 ejects ink in conjunction with the reciprocating motion of the carriage 21 along the scanning direction and the transport of the medium P in the transport direction. As a result, the ink ejected by the print head 22 can be landed on any surface of the medium P, and a desired image is formed on the medium P.

[0019] 1-2. Schematic structure of the print head Next, an example of the structure of the print head 22 of the head unit 20 will be described. Figure 2 is an exploded perspective view showing the structure of the print head 22, Figure 3 is a plan view of the print head 22 as seen along the Z axis, Figure 4 is a cross-sectional view of the print head 22 in the Aa section shown in Figure 3, Figure 5 is a detailed view of the main parts of Figure 4, and Figure 6 is a cross-sectional view of the print head 22 in the Bb section shown in Figure 3. Note that in Figure 3, the peripheral configuration of the pressure chamber substrate 310 is mainly shown, and the protective substrate 330 and case members 340 are omitted from the illustration, and in Figure 4, the configuration of the piezoelectric element 60 is shown in a simplified manner.

[0020] As shown in Figure 2, the print head 22 includes a pressure chamber substrate 310, a communication plate 315, a nozzle plate 320, a compliance substrate 345, a protective substrate 330, a case member 340, and a wiring substrate 420, as well as a diaphragm 350 and a piezoelectric element 60, which will be described later.

[0021] The pressure chamber substrate 310 is made of, for example, a silicon substrate, a glass substrate, an SOI substrate, or various ceramic substrates. As shown in Figure 3, the pressure chamber substrate 310 has two rows of pressure chambers, each row of pressure chambers 312 arranged side by side along the Y-axis, and these rows are arranged along the X-axis. In this case, the multiple pressure chambers 312 are arranged on a straight line along the Y-axis such that the positions of the pressure chambers 312 forming each row of pressure chambers are the same along the X-axis. The pressure chambers 312 adjacent to each other along the Y-axis are separated by a partition wall 311, as shown in Figure 6. Note that the arrangement of the pressure chambers 312 on the pressure chamber substrate 310 is not limited to the arrangement described above. For example, the multiple pressure chambers 312 may be arranged on a straight line along the Y-axis such that the positions of the pressure chambers 312 forming each row of pressure chambers are different along the X-axis. In the following explanation, of the two rows of pressure chambers formed on the pressure chamber substrate 310, the row of pressure chambers located on the +X side may be referred to as the first row of pressure chambers, and the row of pressure chambers located on the -X side of the first row of pressure chambers may be referred to as the second row of pressure chambers.

[0022] Furthermore, the pressure chamber 312 is formed in a so-called rectangle shape, where the length along the X-axis is longer than the length along the Y-axis when viewed from the +Z side in a plan view. Of course, the shape of the pressure chamber 312 in a plan view from the +Z side is not limited to a rectangle, but may be a parallelogram, polygon, circle, oval, etc. Here, an oval shape refers to a shape based on a rectangle with semicircular ends along its longitudinal direction, and includes rounded rectangles, ellipses, egg shapes, etc.

[0023] As shown in Figure 2, a communication plate 315, a nozzle plate 320, and a compliance substrate 345 are stacked on the +Z side of the pressure chamber substrate 310.

[0024] As shown in Figures 2, 4, and 5, the communication plate 315 has a nozzle communication passage 316, a first manifold section 317, a second manifold section 318, and a supply communication passage 319. The first manifold section 317 penetrates the communication plate 315 in the direction along the Z axis. The second manifold section 318 communicates with the first manifold section 317 and opens to the +Z side surface without penetrating the communication plate 315 in the direction along the Z axis. The first manifold section 317 and the second manifold section 318 constitute a part of the manifold 400, which is a common liquid chamber through which multiple pressure chambers 312 communicate. The supply communication passage 319 is provided independently corresponding to each of the multiple pressure chambers 312 and connects one end of the corresponding pressure chamber 312 in the direction along the X axis to the second manifold section 318. As a result, ink stored in the manifold 400 is supplied to each pressure chamber 312. Furthermore, the nozzle communication passage 316 connects the pressure chamber 312 and the nozzle 321.

[0025] Such a connecting plate 315 can be a silicon substrate, glass substrate, SOI substrate, various ceramic substrates, metal substrate, etc. Examples of metal substrates include stainless steel substrates. It is preferable that the connecting plate 315 be made of a material with approximately the same thermal expansion coefficient as the pressure chamber substrate 310. This reduces the risk of warping occurring in the pressure chamber substrate 310 and the connecting plate 315 due to differences in thermal expansion coefficients, even when the temperatures of the pressure chamber substrate 310 and the connecting plate 315 change.

[0026] The nozzle plate 320 is located on the opposite side of the communication plate 315 from the pressure chamber substrate 310, that is, on the +Z side of the communication plate 315. The nozzle plate 320 has a plurality of nozzles 321 that communicate with each pressure chamber 312 via a nozzle communication passage 316. Specifically, the nozzle plate 320 has two rows of nozzles arranged along the X axis, with a plurality of nozzles 321 arranged side by side along the Y axis. These two rows of nozzles correspond to the first pressure chamber row and the second pressure chamber row, respectively. Furthermore, the plurality of nozzles 321 are arranged on a straight line along the Y axis such that the positions of the nozzles 321 forming each nozzle row are the same along the X axis. Note that the arrangement of the nozzles 321 on the nozzle plate 320 is not limited to the arrangement described above; for example, the plurality of nozzles 321 may be arranged on a straight line along the Y axis such that the positions of the nozzles 321 forming each nozzle row are different along the X axis. In other words, the print head 22 of this embodiment has a plurality of nozzles 321, and the plurality of nozzles 321 are arranged in a line along the Y axis on the nozzle plate 320.

[0027] The material of the nozzle plate 320 is not particularly limited, and for example, a silicon substrate, glass substrate, SOI substrate, various ceramic substrates, or metal substrate may be used, or an organic material such as polyimide resin may be used. Examples of metal substrates used for the nozzle plate 320 include stainless steel substrates. However, it is preferable to use a material for the nozzle plate 320 that has approximately the same thermal expansion coefficient as the communication plate 315. This reduces the risk of warping of the nozzle plate 320 and the communication plate 315 due to differences in thermal expansion coefficients when the temperature of the nozzle plate 320 and the communication plate 315 changes.

[0028] The compliance substrate 345 is located together with the nozzle plate 320 on the opposite side of the communication plate 315 from the pressure chamber substrate 310, i.e., on the +Z side of the communication plate 315. The compliance substrate 345 is located around the nozzle plate 320 and seals the +Z side openings of the first manifold portion 317 and the second manifold portion 318 formed in the communication plate 315. The compliance substrate 345 includes a sealing film 346 made of a flexible thin film and a fixed substrate 347 made of a hard material such as metal. Furthermore, an opening 348 is formed in the region of the fixed substrate 347 facing the manifold 400, with the thickness direction completely removed. That is, one side of the manifold 400 is a compliance portion 349 sealed only by the flexible sealing film 346.

[0029] On the other hand, on the opposite side of the pressure chamber substrate 310 from the nozzle plate 320, that is, on the -Z side of the pressure chamber substrate 310, the diaphragm 350 and the piezoelectric element 60 are stacked. In other words, the diaphragm 350 is located on the +Z side in the direction along the Z axis relative to the piezoelectric element 60, and the pressure chamber substrate 310 is located on the +Z side in the direction along the Z axis relative to the diaphragm 350.

[0030] Furthermore, a protective substrate 330, which is approximately the same size as the pressure chamber substrate 310, is located on the -Z side of the pressure chamber substrate 310 and is joined to it by adhesive or the like. The protective substrate 330 has a holding portion 331 which is a space for protecting the piezoelectric element 60. This holding portion 331 is provided independently for each row of piezoelectric elements 60 arranged in parallel along the Y axis. In other words, the protective substrate 330 has two holding portions 331 arranged along the X axis. The protective substrate 330 also has a through hole 332 located between the two holding portions 331 arranged along the X axis, which penetrates in the direction along the Z axis.

[0031] Furthermore, a case member 340 is fixed to the protective substrate 330, which together defines a manifold 400 communicating with multiple pressure chambers 312, along with the pressure chamber substrate 310. The case member 340 has substantially the same shape as the communication plate 315 described above when viewed from the -Z side in plan view, and is joined to the protective substrate 330 as well as to the communication plate 315 described above.

[0032] A housing section 341 is formed in the case member 340. The housing section 341 is a space with a depth capable of housing the pressure chamber substrate 310 and the protective substrate 330, and has an opening on the protective substrate 330 side of the case member 340 that is wider than the surface of the protective substrate 330 that is joined to the pressure chamber substrate 310. The opening surface of the housing section 341 on the nozzle plate 320 side is sealed by a communication plate 315 when the pressure chamber substrate 310 and the protective substrate 330 are housed in the housing section 341.

[0033] Furthermore, the case member 340 has third manifold sections 342 formed on both outer sides of the housing section 341 in the direction along the X axis. The manifold 400 is composed of the third manifold sections 342 provided on the case member 340 and the first manifold section 317 and second manifold section 318 provided on the aforementioned communication plate 315. Such manifolds 400 are provided continuously along the Y axis, and the supply passages 319 that connect each pressure chamber 312 to the manifold 400 are arranged in a line along the Y axis.

[0034] Furthermore, the case member 340 has supply ports 344 that communicate with the manifold 400 and supply ink to each manifold 400. In addition, the case member 340 has connection ports 343 that communicate with the through holes 332 of the protective substrate 330 and through which the wiring substrate 420 is inserted.

[0035] Such a print head 22 draws ink stored in an ink container 90 through an ink tube (not shown) or the like from a supply port 344. As a result, the path from the manifold 400 of the print head 22 to the nozzle 321 is filled with ink. Subsequently, an integrated circuit 421 mounted on the wiring board 420 supplies a signal based on a drive signal COM to each piezoelectric element 60 corresponding to the pressure chamber 312. This causes the piezoelectric element 60 to bend and deform, and the deformation of the piezoelectric element 60 causes the diaphragm 350 to bend and deform. This deformation of the diaphragm 350 changes the internal pressure of each pressure chamber 312, and ink is ejected from each nozzle 321 in accordance with this change in internal pressure.

[0036] Next, the details of the configuration including the diaphragm 350 and piezoelectric element 60 described above, which are laminated on the -Z side of the pressure chamber substrate 310, will be explained. The print head 22, as a configuration laminated on the -Z side of the pressure chamber substrate 310, has individual lead electrodes 391, a common lead electrode 392, a measuring lead electrode 393, and resistance wiring 401 in addition to the diaphragm 350 and piezoelectric element 60 described above.

[0037] As shown in Figures 4 to 6, the diaphragm 350 has an elastic film 351 made of silicon oxide provided on the pressure chamber substrate 310 side, and an insulating film 352 made of zirconium oxide provided on the elastic film 351. Furthermore, the liquid flow path including the pressure chamber 312 formed in the pressure chamber substrate 310 is formed by anisotropic etching of the pressure chamber substrate 310 from the +Z side. The diaphragm 350 is positioned to seal the opening on the -Z side of the pressure chamber substrate 310. That is, the -Z side of the liquid flow path such as the pressure chamber 312 formed in the pressure chamber substrate 310 is composed of the diaphragm 350 including the elastic film 351. The composition of the diaphragm 350 is not particularly limited, and for example, it may be composed of only one of the elastic film 351 and the insulating film 352, or it may be composed of other films other than the elastic film 351 and the insulating film 352. Here, other films that constitute the diaphragm 350 include, for example, films such as silicon and silicon nitride.

[0038] The piezoelectric element 60 has electrodes 360, a piezoelectric body 370, and an electrode 380 that are sequentially stacked from the +Z side (which is the diaphragm 350 side) toward the -Z side. That is, the piezoelectric element 60 includes electrodes 360, 380, and 370, and in the direction along the Z axis in which electrodes 360, 380, and 370 are stacked, the piezoelectric body 370 is provided between electrodes 360 and 380. Such a piezoelectric element 60 functions as a piezoelectric actuator that generates a pressure change in the pressure chamber 312.

[0039] Specifically, electrodes 360 and 380 are both electrically connected to the wiring board 420. A signal based on the drive signal COM output by the integrated circuit 421 mounted on the wiring board 420 is supplied to one of electrodes 360 and 380, and a reference potential signal propagating through the wiring board 420 is supplied to the other electrode 360 ​​and 380. As a result, a potential difference is created in the piezoelectric element 370 between the signal based on the drive signal COM supplied from the integrated circuit 421 and the reference potential signal. This potential difference between electrodes 360 and 380 causes the piezoelectric element 370 to deform. In response to the deformation of the piezoelectric element 370, the diaphragm 350 deforms or vibrates, and the volume of the pressure chamber 312 changes due to the deformation or vibration of the diaphragm 350. The change in internal pressure caused by this change in the volume of the pressure chamber 312 is applied to the ink contained in the pressure chamber 312, causing the ink to be ejected from the nozzle 321 via the nozzle communication passage 316. In the following explanation, it will be assumed that a signal based on the drive signal COM output by the integrated circuit 421 mounted on the wiring board 420 is supplied to the electrode 360, and a reference potential signal propagating through the wiring board 420 is supplied to the electrode 380.

[0040] In the following explanation, the portion of the piezoelectric element 60 in which piezoelectric strain occurs in the piezoelectric body 370 when a potential difference is generated between electrodes 360 and 380 may be referred to as the active portion 410, and the portion in which piezoelectric strain does not occur in the piezoelectric body 370 may be referred to as the inactive portion 415. That is, the portion of the piezoelectric element 60 in which the piezoelectric body 370 is sandwiched between electrodes 360 and 380 corresponds to the active portion 410, and the portion of the piezoelectric body 370 not sandwiched between electrodes 360 and 380 corresponds to the inactive portion 415. Furthermore, in the following explanation, the portion of the piezoelectric element 60 that displaces in the direction along the Z axis when driven may be referred to as the flexible portion, and the portion that does not displace in the direction along the Z axis may be referred to as the inflexible portion. That is, the portion of the piezoelectric element 60 that faces the pressure chamber 312 in the direction along the Z axis corresponds to the flexible portion, and the portion outside the pressure chamber 312 corresponds to the inflexible portion. The active part 410 may also be referred to as the active component, and the inactive part 415 as the inactive component.

[0041] Here, generally, one of the electrodes 360 and 380 located in the active section 410 is configured as an individual electrode independent of each active section 410, and the other is configured as a common electrode common to the active sections 410. In the following explanation, it will be assumed that the electrode 360 ​​to which a signal based on the drive signal COM output by the integrated circuit 421 is supplied is an individual electrode, and the electrode 380 to which a reference potential signal propagating through the wiring board 420 is supplied is a common electrode.

[0042] Specifically, the electrode 360 ​​is located on the +Z side relative to the piezoelectric element 370 and is divided for each pressure chamber 312, forming an independent individual electrode for each active section 410. That is, the electrode 360 ​​is individually provided corresponding to multiple pressure chambers 312. Furthermore, the electrode 360 ​​is formed with a width narrower than the width of the pressure chamber 312 in the direction along the Y axis. That is, the end of the electrode 360 ​​is located inside the region facing the pressure chamber 312 in the direction along the Y axis. In addition, the +X side end 360a and the -X side end 360b of the electrode 360 ​​are located outside the pressure chamber 312, respectively. For example, as shown in Figure 5, in the first row of pressure chambers, end 360a is located on the +X side of the pressure chamber 312 than the +X side end 312a, and end 360b is located on the -X side of the pressure chamber 312 than the -X side end 312b.

[0043] The material of such an electrode 360 ​​is not particularly limited. For example, conductive materials such as metals like platinum (Pt), iridium (Ir), gold (Au), and titanium (Ti), or conductive metal oxides such as indium tin oxide (ITO), may be used. Alternatively, a material consisting of multiple materials such as platinum (Pt), iridium (Ir), gold (Au), and titanium (Ti) stacked together may be used. In this embodiment, the electrode 360 ​​will be described assuming it is made of platinum (Pt).

[0044] Furthermore, as shown in Figure 3, the piezoelectric element 370 is provided continuously along the Y-axis with a predetermined length along the X-axis. That is, the piezoelectric element 370 is provided continuously with a predetermined thickness along the direction in which the pressure chambers 312 are arranged side by side. The thickness of such piezoelectric element 370 is not particularly limited and can be formed with a thickness of, for example, 1,000 nanometers to 4,000 nanometers.

[0045] Furthermore, as shown in Figure 5, the length of the piezoelectric element 370 along the X-axis is longer than the length of the pressure chamber 312 along the X-axis, which is the longitudinal direction of the pressure chamber 312. Therefore, on both sides of the pressure chamber 312 along the X-axis, the piezoelectric element 370 extends to the outside of the pressure chamber 312. In this way, the extension of the piezoelectric element 370 to the outside of the pressure chamber 312 along the X-axis improves the strength of the diaphragm 350. Consequently, the risk of cracks or other damage occurring in the diaphragm 350 or piezoelectric element 60 when the active part 410 is driven is reduced.

[0046] Furthermore, as shown in Figure 5, for example, in the first pressure chamber row, the +X side end 370a of the piezoelectric element 370 is located on the +X side, outside of the end 360a of the electrode 360. That is, the end 360a of the electrode 360 ​​is covered by the piezoelectric element 370. On the other hand, the -X side end 370b of the piezoelectric element 370 is located on the +X side, inside of the end 360b of the electrode 360. That is, the end 360b of the electrode 360 ​​is not covered by the piezoelectric element 370.

[0047] Furthermore, as shown in Figures 3 and 6, the piezoelectric element 370 has grooves 371 formed in each partition wall 311, which are thinner than other areas. In this embodiment, the grooves 371 are formed by completely removing the piezoelectric element 370 in the direction along the Z-axis. That is, having a portion of the piezoelectric element 370 that is thinner than other areas is not limited to cases where the piezoelectric element 370 is formed thinner than other parts on the bottom surface of the groove 371, but also includes cases where the piezoelectric element 370 is completely removed in the direction along the Z-axis. Also, the length of the groove 371 in the direction along the Y-axis, i.e., the width of the groove 371, is the same as or wider than the width of the partition wall 311. In this embodiment, the width of the groove 371 is wider than the width of the partition wall 311. Such grooves 371 are formed to be rectangular in shape when viewed from the -Z side in plan view. Of course, the shape of the groove 371 when viewed from the -Z side in plan view is not limited to a rectangle, but may be a polygon with five or more sides, or it may be circular or elliptical, etc.

[0048] By providing grooves 371 in the piezoelectric body 370, the rigidity of the portion of the diaphragm 350 facing the end of the pressure chamber 312 in the direction along the Y axis, the so-called arm portion of the diaphragm 350, is suppressed, thereby allowing the piezoelectric element 60 to be displaced more effectively.

[0049] Examples of such piezoelectric materials 370 include perovskite crystal films made of ferroelectric ceramic material exhibiting electromechanical conversion properties formed on the electrode 360, so-called perovskite crystals. Examples of materials for such piezoelectric materials 370 include ferroelectric piezoelectric materials such as lead zirconate titanate (PZT), or materials to which metal oxides such as niobium oxide, nickel oxide, or magnesium oxide are added. Specifically, lead titanate (PbTiO3), lead zirconate titanate (Pb(Zr,Ti)O3), lead zirconate (PbZrO3), lead lanthanum titanate ((Pb,La),TiO3), lead zirconate titanate lanthanum ((Pb,La)(Zr,Ti)O3), or magnesium zirconium titanate lead (Pb(Zr,Ti)(Mg,Nb)O3). In this embodiment, the piezoelectric element 370 is assumed to be lead zirconate titanate (PZT).

[0050] Furthermore, the material for the piezoelectric element 370 is not limited to lead-based piezoelectric materials containing lead; lead-free piezoelectric materials can also be used. Examples of such lead-free piezoelectric materials include bismuth ironate ((BiFeO3), abbreviated as "BFO"), barium titanate ((BaTiO3), abbreviated as "BT"), potassium sodium niobate ((K,Na)(NbO3), abbreviated as "KNN"), potassium sodium lithium niobate ((K,Na,Li)(NbO3)), potassium sodium lithium tantalate niobate ((K,Na,Li)(Nb,Ta)O3), potassium bismuth titanate ((Bi1 / 2K1 / 2)TiO3, abbreviated as "BKT"), sodium bismuth titanate ((Bi1 / 2Na1 / 2)TiO3, abbreviated as "BNT"), Examples include bismuth manganate (BiMnO3, abbreviated as "BM"), a composite oxide containing bismuth, potassium, titanium, and iron and having a perovskite structure (x[(BixK1-x)TiO3]-(1-x)[BiFeO3], abbreviated as "BKT-BF"), a composite oxide containing bismuth, iron, barium, and titanium and having a perovskite structure ((1-x)[BiFeO3]-x[BaTiO3], abbreviated as "BFO-BT"), and those to which metals such as manganese, cobalt, and chromium are added ((1-x)[Bi(Fe1-yMy)O3]-x[BaTiO3] (where M is Mn, Co, or Cr)).

[0051] As shown in Figures 3, 5, and 6, the electrode 380 is located on the opposite side of the piezoelectric body 370 from the electrode 360, on the -Z side of the piezoelectric body 370, and constitutes a common electrode common to multiple active parts 410. That is, the electrode 380 is provided in common to multiple pressure chambers 312. The electrode 380 is provided continuously along the Y-axis with a predetermined length along the X-axis. This electrode 380 is also provided on the inner surface of the groove 371, that is, on the side surface of the groove 371 of the piezoelectric body 370 and on the insulating film 352 which is the bottom surface of the groove 371. Regarding the inside of the groove 371, the electrode 380 may be provided only on a part of the inner surface of the groove 371, or it may not be provided over the entire inner surface of the groove 371.

[0052] Furthermore, as shown in Figure 5, for example, in the first pressure chamber row, the +X side end 380a of electrode 380 is positioned on the +X side such that it is outside the end 360a of electrode 360, which is covered by the piezoelectric element 370. That is, the end 380a of electrode 380 is on the +X side, outside the end 312a of pressure chamber 312, and outside the +X side, outside the end 360a of electrode 360. In this embodiment, the end 380a of electrode 380 substantially coincides with the end 370a of piezoelectric element 370 in the direction along the X axis. Therefore, the +X side end of the active part 410, i.e., the boundary between the active part 410 and the inactive part 415, is defined by the end 360a of electrode 360.

[0053] On the other hand, the -X end 380b of electrode 380 is located on the -X side, outside the end 312b of pressure chamber 312, and on the +X side, inside the end 370b of piezoelectric body 370. As described above, the end 370b of piezoelectric body 370 is located inside the end 360b of electrode 360, on the +X side. Therefore, the end 380b of electrode 380 is located on the piezoelectric body 370, on the +X side, beyond the end 360b of electrode 360. As a result, there is an exposed surface portion of the piezoelectric body 370 on the -X side of the end 380b of electrode 380. Thus, the end 380b of electrode 380 is located on the +X side, beyond the end 370b of piezoelectric body 370 and beyond the end 360b of electrode 360. Therefore, the -X end of the active part 410, i.e., the boundary between the active part 410 and the inactive part 415, is defined by the end 380b of electrode 380.

[0054] The material of such electrode 380 is not particularly limited. For example, similar to electrode 360, conductive materials such as metals like platinum (Pt), iridium (Ir), gold (Au), and titanium (Ti), or conductive metal oxides such as indium tin oxide (ITO) may be used. Alternatively, multiple materials such as platinum (Pt), iridium (Ir), gold (Au), and titanium (Ti) may be laminated together to form the electrode. In this embodiment, electrode 380 will be described assuming it is made of iridium (Ir).

[0055] Furthermore, outside the end 380b of electrode 380, that is, further to the -X side of the end 380b of electrode 380, there is a wiring section 385 which is on the same layer as electrode 380 but is electrically discontinuous from electrode 380. The wiring section 385 is formed on electrode 360 ​​which extends from above piezoelectric body 370 to the -X side of piezoelectric body 370, with a gap so as not to contact the end 380b of electrode 380. This wiring section 385 is provided independently for each active section 410. In other words, multiple wiring sections 385 are arranged at predetermined intervals in the direction along the Y axis. Note that the wiring section 385 may be formed in a different layer from electrode 380, but it is preferable that it be formed in the same layer as electrode 380. This simplifies the manufacturing process of the wiring section 385 and reduces costs.

[0056] Furthermore, individual lead electrodes 391 are connected to the electrodes 360 that constitute the piezoelectric element 60, and a common lead electrode 392, which is a common drive electrode, is electrically connected to electrode 380. In both the individual lead electrodes 391 and the common lead electrode 392, one end along the X-axis is connected to the piezoelectric element 60, and the other end is connected to the wiring board 420. Multiple wirings for connecting to the control unit 10, the temperature information output circuit 26 (described later), and multiple circuits (not shown) are formed on the wiring board 420. Such a wiring board 420 is made of, for example, an FPC (Flexible Printed Circuit).

[0057] In this embodiment, the individual lead electrodes 391 and the common lead electrode 392 extend to be exposed within through holes 332 formed in the protective substrate 330, and are electrically connected to the wiring board 420 within these through holes 332. Furthermore, an integrated circuit 421 that outputs signals for driving the piezoelectric element 60 is mounted on the wiring board 420.

[0058] The material of the individual lead electrodes 391 and common lead electrode 392 is not particularly limited as long as it is an conductive material, and for example, gold (Au), copper (Cu), titanium (Ti), tungsten (W), nickel (Ni), chromium (Cr), platinum (Pt), aluminum (Al), etc. can be used. In this embodiment, the individual lead electrodes 391 and common lead electrode 392 will be described assuming that they are made of gold (Au). The individual lead electrodes 391 and common lead electrode 392 may also have an adhesion layer to improve adhesion with electrodes 360 and 380 and the diaphragm 350.

[0059] Individual lead electrodes 391 are provided for each active section 410, that is, for each electrode 360. For example, as shown in Figure 5, in the first pressure chamber row, the individual lead electrodes 391 are connected via the wiring section 385 to the vicinity of the end 360b of the electrode 360 ​​provided on the outside of the piezoelectric element 370, and are led out in the -X direction onto the pressure chamber substrate 310, and actually onto the diaphragm 350.

[0060] On the other hand, as shown in Figure 3, in the first pressure chamber row, the common lead electrode 392 is drawn out to the -X side from the electrode 380 constituting the common electrode on the piezoelectric body 370 to the diaphragm 350 at both ends in the direction along the Y axis. The common lead electrode 392 also has extension portions 392a and 392b. As shown in Figures 3 and 5, for example, in the first pressure chamber row, the extension portion 392a extends along the Y axis to the region corresponding to the end 312a of the pressure chamber 312, and the extension portion 392b extends along the Y axis to the region corresponding to the end 312b of the pressure chamber 312. These extension portions 392a and 392b are continuously provided across the Y axis for a plurality of active parts 410.

[0061] Furthermore, the extensions 392a and 392b extend from the inside of the pressure chamber 312 to the outside of the pressure chamber 312 in the direction along the X axis. In this embodiment, the active portion 410 of the piezoelectric element 60 extends to the outside of the pressure chamber 312 at both ends in the direction along the X axis of the pressure chamber 312, and the extensions 392a and 392b extend on this active portion 410 to the outside of the pressure chamber 312.

[0062] As shown in Figure 5, a resistive wiring 401 is provided on the -Z side surface of the diaphragm 350. The resistive wiring 401 detects the temperature of the pressure chamber 312 by utilizing the characteristic that its electrical resistance changes with temperature. As the material for such resistive wiring 401, a material whose electrical resistance is temperature-dependent can be used, such as gold (Au), platinum (Pt), iridium (Ir), aluminum (Al), copper (Cu), titanium (Ti), tungsten (W), nickel (Ni), chromium (Cr), etc.

[0063] Of these, platinum (Pt) exhibits a large change in resistance with temperature, as well as high stability and accuracy. Furthermore, platinum (Pt) also exhibits high linearity in the change in resistance with respect to temperature changes. From this viewpoint, platinum (Pt) is preferably used as the material for the resistive wiring 401. That is, it is preferable that the resistive wiring 401 is composed of platinum (Pt). In this embodiment, the resistive wiring 401 is in the same layer as the electrode 360, and is laminated on the -Z side surface of the diaphragm 350 so as to be electrically discontinuous with the electrode 360. That is, the resistive wiring 401 includes a wiring pattern laminated on the -Z side surface in the direction along the Z axis of the diaphragm 350, and this wiring pattern includes platinum (Pt).

[0064] As shown in Figure 3, one end of the resistance wiring 401 is connected to the measuring lead electrode 393a, and the other end of the resistance wiring 401 is connected to the measuring lead electrode 393b. Furthermore, the measuring lead electrodes 393a and 393b are electrically connected to the wiring board 420. As a result, the print head 22 outputs a signal of voltage corresponding to the temperature of the pressure chamber 312 detected by the resistance wiring 401, and the electrical resistance value that changes with the temperature of the pressure chamber 312.

[0065] In this embodiment, the resistance wiring 401 is covered by the piezoelectric element 370 and is located between the diaphragm 350 and the piezoelectric element 370 in the direction along the Z axis. The resistance wiring 401 includes a first pressure chamber row-side meandering pattern located on the +X side in the direction along the X axis, and a second pressure chamber row-side meandering pattern located on the -X side in the direction along the X axis. The first pressure chamber row-side meandering pattern is located so as to overlap with the supply passage 319 communicating with each pressure chamber 312 constituting the first pressure chamber row when viewed from the -Z side, and meanders in the direction along the Y axis. The second pressure chamber row-side meandering pattern is located so as to overlap with the supply passage 319 communicating with each pressure chamber 312 constituting the second pressure chamber row when viewed from the -Z side, and meanders in the direction along the Y axis. In other words, the resistance wiring 401 includes a first pressure chamber row-side meandering pattern corresponding to a first pressure chamber row formed by a plurality of pressure chambers 312, and a second pressure chamber row-side meandering pattern corresponding to a second pressure chamber row formed by a plurality of pressure chambers 312.

[0066] Furthermore, as shown in Figures 4 and 5, the distance along the Z-axis between the -Z end of the pressure chamber 312 and the resistance wiring 401 is shorter than the dimension of the pressure chamber 312 along the Z-axis. Also, for example, in the first pressure chamber row, the longest distance along the X-axis between the +X end 312a of the pressure chamber 312 and the resistance wiring 401 is shorter than the dimension of the pressure chamber 312 along the X-axis. For this reason, the electrical resistance value of the resistance wiring 401 is prone to changing in response to temperature changes in the pressure chamber 312.

[0067] In this embodiment, the measuring lead electrode 393, including measuring lead electrodes 393a and 393b, is made of the same single layer as the individual lead electrodes 391 and the common lead electrode 392, but is formed to be electrically discontinuous. This simplifies the manufacturing process and reduces costs compared to forming the measuring lead electrode 393 separately from the individual lead electrodes 391 and the common lead electrode 392. Of course, the measuring lead electrode 393 may also be formed from a different layer than the individual lead electrodes 391 and the common lead electrode 392.

[0068] The material of such measuring lead electrodes 393 is not particularly limited as long as it is a conductive material, and for example, gold (Au), copper (Cu), titanium (Ti), tungsten (W), nickel (Ni), chromium (Cr), platinum (Pt), aluminum (Al), etc. can be used. In this embodiment, the measuring lead electrodes 393 will be described assuming that they are made of gold (Au). That is, the material of the measuring lead electrodes 393 in this embodiment is the same as that of the individual lead electrodes 391 and the common lead electrode 392. In addition, the measuring lead electrodes 393 may have an adhesion layer to improve adhesion with the resistance wiring 401 and the diaphragm 350.

[0069] As described above, in this embodiment, the measuring lead electrode 393 extends so as to be exposed within a through hole 332 formed in the protective substrate 330, and is electrically connected to the wiring board 420 within the through hole 332. As a result, the electrical resistance value of the resistance wiring 401, which changes with the temperature of the pressure chamber 312, is output from the print head 22 via the wiring board 420.

[0070] In other words, the print head 22 of the head unit 20 of this embodiment includes an electrode 360, an electrode 380, and a piezoelectric element 370, wherein the piezoelectric element 60 is located between the electrode 360 ​​and the electrode 380 in the direction along the Z-axis in which the electrode 360, electrode 380, and piezoelectric element 370 are stacked, and is driven by receiving a drive signal COM; a diaphragm 350 located on the +Z side, which is one side along the Z-axis with respect to the piezoelectric element 60, and deforms when driven by the piezoelectric element 60; a pressure chamber substrate 310 located on the +Z side, which is one side along the Z-axis with respect to the diaphragm 350, and is provided with a pressure chamber 312 in which ink is stored and whose volume changes when the diaphragm 350 deforms; a nozzle 321 that ejects ink in accordance with the change in volume of the pressure chamber 312; and a resistance wiring 401 located on the -Z side, which is the other side along the Z-axis with respect to the diaphragm 350, and acquires a temperature corresponding to the temperature of the pressure chamber 312.

[0071] 1-3. Configuration of the liquid dispensing device Next, the functional configuration of the liquid dispensing device 1 will be described. Figure 7 is a diagram showing the functional configuration of the liquid dispensing device 1. As shown in Figure 7, the liquid dispensing device 1 comprises a control unit 10, a head unit 20, a carriage motor 31, a transport motor 41, an encoder sensor 92, and a notification circuit 94.

[0072] The control unit 10 includes a drive circuit 50, a reference voltage output circuit 52, and a control circuit 100. The control circuit 100 includes, for example, a processing circuit such as a CPU or FPGA and a storage circuit such as a semiconductor memory. The control circuit 100 receives image information signals, including image data, from an external device such as a host computer that is communicatively connected to the liquid dispensing device 1. Based on the input image information signals, the control circuit 100 generates various signals for controlling the liquid dispensing device 1 and outputs them to the corresponding configurations.

[0073] In a specific example, in addition to the image information signal described above, the control circuit 100 receives a position detection signal PS from the encoder sensor 92, which is based on the scanning position of the carriage 21 included in the head unit 20. Based on the input position detection signal PS, the control circuit 100 determines the scanning position of the carriage 21, which is the scanning position of the head unit 20 including the print head 22 mounted on the carriage 21. The control circuit 100 then generates various signals corresponding to the input image information signal and the determined scanning position of the head unit 20, and outputs them to the corresponding configuration.

[0074] In detail, the control circuit 100 generates a control signal Ctrl-C to control the movement of the head unit 20 along the scanning axis according to the scanning position of the head unit 20, and outputs it to the carriage motor 31. This causes the carriage motor 31 to operate, controlling the movement of the head unit 20 mounted on the carriage 21 along the scanning axis and its scanning position. The control circuit 100 also generates a control signal Ctrl-T to control the transport of the medium P, and outputs it to the transport motor 41. This causes the transport motor 41 to operate, controlling the movement of the medium P along the transport direction. Note that the control signal Ctrl-C may be input to the carriage motor 31 after signal conversion via a driver circuit (not shown), and the control signal Ctrl-T may be input to the transport motor 41 after signal conversion via a driver circuit (not shown).

[0075] Furthermore, based on the image information signals input from the external device and the scanning position of the head unit 20, the control circuit 100 generates print data signals SI1~SIn, a change signal CH, a latch signal LAT, and a clock signal SCK as control signals Ctrl-H for controlling the head unit 20, and outputs them to the head unit 20.

[0076] Furthermore, the control circuit 100 generates a temperature acquisition request signal TD to obtain temperature information of the head unit 20 and outputs it to the head unit 20. As a result, the control circuit 100 receives a temperature information signal TI containing the temperature information of the head unit 20 corresponding to the temperature acquisition request signal TD. Based on the input temperature information signal TI, the control circuit 100 determines the temperature of the head unit 20 and corrects the control signals Ctrl-H, Ctrl-C, and Ctrl-T based on the determined temperature, and outputs them to the corresponding configuration. In this way, the operation of the liquid ejection device 1 and the head unit 20 is controlled according to the temperature information signal TI based on the temperature of the print head 22. As a result, the ejection accuracy of the ink ejected from the liquid ejection device 1 and the head unit 20 is improved.

[0077] Furthermore, the control circuit 100 generates a base drive signal dA, which is a digital signal, as the control signal Ctrl-H, and outputs it to the drive circuit 50. The drive circuit 50 generates a drive signal COM, which has a signal waveform defined by the base drive signal dA, and outputs it to the head unit 20.

[0078] Specifically, the base drive signal dA output by the control circuit 100 is input to the drive circuit 50. The drive circuit 50 converts the input base drive signal dA from a digital to an analog signal, then generates a drive signal COM by class D amplification of the converted analog signal, and outputs it to the head unit 20. That is, the control circuit 100 outputs the base drive signal dA as a control signal Ctrl-H corrected based on the temperature information signal TI, and the drive circuit 50 outputs a drive signal COM with a signal waveform corrected according to the base drive signal dA corrected based on the temperature information signal TI. Here, the base drive signal dA output by the control circuit 100 is described as a digital signal that defines the signal waveform of the drive signal COM, but the base drive signal dA only needs to define the signal waveform of the drive signal COM, and may be an analog signal. Also, the drive circuit 50 may generate the drive signal COM by class A amplification, class B amplification, or class AB amplification of the signal waveform defined by the base drive signal dA.

[0079] As described above, the drive circuit 50 generates and outputs a drive signal COM based on the base drive signal dA. At this time, the base drive signal dA input to the drive circuit 50, which is output by the control circuit 100, is also corrected based on the temperature of the head unit 20 as determined by the temperature information signal TI. Therefore, the drive circuit 50 outputs a drive signal COM that has been corrected based on the temperature of the head unit 20.

[0080] The reference voltage output circuit 52 generates a reference voltage signal VBS and outputs it to the head unit 20. This reference voltage signal VBS is a signal with a constant voltage value that serves as a reference for driving the piezoelectric element 60, and is supplied to the electrode 380, which is a common electrode. The voltage value of such a reference voltage signal VBS may be a signal that is constant at ground potential, or a signal that is constant at a potential such as 5.5V or 6V.

[0081] Furthermore, the control circuit 100 generates a control signal Ctrl-M to inform the user of the operating status of the drive circuit 50, the reference voltage output circuit 52, and the head unit 20, and outputs it to the notification circuit 94. The notification circuit 94 informs the user of information corresponding to the control signal Ctrl-M. In this way, the operating status of the liquid dispensing device 1 is informed to the user. Such a notification circuit 94 may be a display that informs the user of the information using characters or images, or it may be a speaker that informs the user of the information using sound.

[0082] The head unit 20 includes a plurality of print heads 22-1 to 22-n, a temperature information output circuit 26, and a temperature detection circuit 28. Each of the print heads 22-1 to 22-n also includes a drive signal selection circuit 200, a temperature detection circuit 250, and a plurality of piezoelectric elements 60.

[0083] The print head 22-1 receives the print data signal SI1, change signal CH, latch signal LAT, clock signal SCK, drive signal COM, and reference voltage signal VBS, which are output by the control circuit 100. The clock signal SCK, latch signal LAT, change signal CH, print data signal SI1, and drive signal COM input to the print head 22-1 are then input to the drive signal selection circuit 200.

[0084] The drive signal selection circuit 200 generates a drive signal VOUT corresponding to each of the multiple piezoelectric elements 60 by selecting or deselecting the signal waveform included in the drive signal COM based on the input clock signal SCK, latch signal LAT, change signal CH, and print data signal SI1. The drive signal selection circuit 200 then outputs the generated drive signal VOUT to each of the individual electrodes 360 at one end of each corresponding piezoelectric element 60. At this time, a reference voltage signal VBS is commonly input to the common electrode 380 at the other end of the multiple piezoelectric elements 60. As a result, each of the multiple piezoelectric elements 60 is displaced by the potential difference between the drive signal VOUT input to electrode 360 ​​and the reference voltage signal VBS input to electrode 380. Consequently, an amount of ink corresponding to the displacement of the piezoelectric element 60 is ejected from the corresponding nozzle 321 of the print head 22-1.

[0085] In other words, the print head 22-1 ejects ink upon receiving the drive signal COM. Here, at least a portion of the drive signal selection circuit 200 may be mounted on the wiring board 420 of the print head 22-1 as the integrated circuit 421 described above.

[0086] Furthermore, the temperature detection circuit 250 of the print head 22-1 detects the temperature of the print head 22-1. The temperature detection circuit 250 then outputs a head temperature signal TC1 corresponding to the detected temperature of the print head 22-1 to the temperature information output circuit 26. Here, part of the temperature detection circuit 250 may be provided on the print head 22-1, and a different part may be provided outside the print head 22-1. In this case, the part of the temperature detection circuit 250 provided on the print head 22-1 corresponds to the resistor wiring 401 described above. That is, the voltage value of the head temperature signal TC1 output by the temperature detection circuit 250, which corresponds to the temperature of the print head 22-1, changes according to the resistance value of the resistor wiring 401, which changes with temperature. In other words, the voltage value of the head temperature signal TC1 output by the temperature detection circuit 250 is the temperature of the print head 22-1, and changes according to the temperature of the pressure chamber 312 of the print head 22-1.

[0087] Print heads 22-2 to 22-n have the same configuration as print head 22-1 and perform the same operation, differing only in the input and output signals. Specifically, print head 22-i (where i is one of 2 to n) receives the clock signal SCK, latch signal LAT, change signal CH, print data signal SIi, drive signal COM, and reference voltage signal VBS. The drive signal selection circuit 200 in print head 22-i selects or deselects the signal waveform of the drive signal COM based on the input clock signal SCK, latch signal LAT, change signal CH, and print data signal SIi, thereby generating a drive signal VOUT corresponding to each of the multiple piezoelectric elements 60, and outputting it to the electrode 360 ​​of the corresponding piezoelectric element 60. In addition, the electrode 380 of the multiple piezoelectric elements 60 in print head 22-i is commonly input to the reference voltage signal VBS. As a result, multiple piezoelectric elements 60 on the print head 22-i are driven, and an amount of ink corresponding to the drive of the piezoelectric elements 60 is ejected from the nozzles 321 on the print head 22-i. In other words, print heads 22-2 to 22-n also eject ink upon receiving the drive signal COM.

[0088] Furthermore, the temperature detection circuit 250 of the print head 22-i outputs a head temperature signal TCi, which is a voltage value corresponding to the temperature of the print head 22-i, to the temperature information output circuit 26. Here, at least a portion of the drive signal selection circuit 200 of the print head 22-i is mounted on the wiring board 420 of the print head 22-i as the integrated circuit 421 described above, and at least a portion of the temperature detection circuit 250 of the print head 22-i is provided on the print head 22-i as the resistor wiring 401 described above.

[0089] In the following explanation, it will be assumed that when print heads 22-1 to 22-n are not distinguished, the print head 22 receives the following inputs: a clock signal SCK, a latch signal LAT, a change signal CH, print data signals SI (as print data signals SI1 to SIn), a drive signal COM, and a reference voltage signal VBS. Furthermore, it will be assumed that the temperature detection circuit 250 of the print head 22 outputs a head temperature signal TC (as head temperature signals TC1 to TCn) with a voltage value corresponding to the temperature of the print head 22.

[0090] The temperature detection circuit 28 detects the temperature of the head unit 20, including the print heads 22-1 to 22-n. The temperature detection circuit 28 then generates a unit temperature signal TH with a voltage value corresponding to the detected temperature. The temperature detection circuit 28 outputs the generated unit temperature signal TH to the temperature information output circuit 26 and the control circuit 100. Such a temperature detection circuit 28 is configured to include a thermistor element or the like, whose resistance value changes in response to temperature changes in the head unit 20.

[0091] The temperature information output circuit 26 generates a temperature information signal TI in accordance with the head temperature signals TC1 to TCn output by each of the print heads 22-1 to 22-n, the unit temperature signal TH output by the temperature detection circuit 28, the temperature acquisition request signal TD output by the control circuit 100, and the drive signal COM output by the drive circuit 50, and outputs it to the control circuit 100.

[0092] Specifically, the temperature information output circuit 26 selects a head temperature signal TC from the head temperature signals TC1 to TCn in response to a temperature acquisition request signal TD input from the control circuit 100, and acquires a digital signal corresponding to the selected head temperature signal TC at a timing corresponding to the voltage value of the drive signal COM output by the drive circuit 50. Then, it corrects the acquired digital signal based on the unit temperature signal TH and outputs a temperature information signal TI corresponding to the corrected signal to the control circuit 100. In other words, the temperature information output circuit 26 acquires head temperature signals TC1 to TCn corresponding to the temperatures of the print heads 22-1 to 22-n. Then, it generates a temperature information signal TI corresponding to the acquired head temperature signals TC1 to TCn and outputs it to the control circuit 100. Details of the configuration and operation of this temperature information output circuit 26 will be described later.

[0093] 1-4. Signal waveform of drive signal COM and configuration of drive signal selection circuit Next, the configuration and operation of the drive signal selection circuit 200 of the print head 22 will be described. As mentioned above, the drive signal selection circuit 200 of the print head 22 generates a drive signal VOUT by selecting or deselecting the signal waveform included in the drive signal COM based on the clock signal SCK, the print data signal SI, the latch signal LAT, and the change signal CH, and outputs it to the corresponding piezoelectric element 60. In order to describe the configuration and operation of the drive signal selection circuit 200, first, an example of the waveform of the drive signal COM input to the drive signal selection circuit 200 during the period in which ink is ejected onto the medium P will be described. Here, in the following description, the period in which ink is ejected onto the medium P may be referred to as the ejection period.

[0094] Figure 8 shows an example of the signal waveform of the drive signal COM during the ejection period. As shown in Figure 8, during the ejection period, the drive signal COM includes a trapezoidal waveform Adp positioned during period t1 from when the latch signal LAT rises until when the change signal CH rises, a trapezoidal waveform Bdp positioned during period t2 from when the change signal CH rises until the next change signal CH rises, and a trapezoidal waveform Cdp positioned during period t3 from when the change signal CH rises until the latch signal LAT rises. The trapezoidal waveform Adp is a signal waveform that drives the piezoelectric element 60 so that a predetermined amount of ink is ejected, the trapezoidal waveform Bdp is a signal waveform that drives the piezoelectric element 60 so that a smaller amount of ink than the predetermined amount is ejected, and the trapezoidal waveform Cdp is a signal waveform that drives the piezoelectric element 60 to the extent that no ink is ejected. Here, the trapezoidal waveform Cdp is a signal waveform that, when supplied to the corresponding piezoelectric element 60, vibrates the ink near the corresponding nozzle opening, thereby reducing the risk of an increase in ink viscosity near the nozzle opening.

[0095] Furthermore, the trapezoidal waveforms Adp, Bdp, and Cdp are signal waveforms that share a common voltage value Vc at their respective start and end timings. In other words, each of the trapezoidal waveforms Adp, Bdp, and Cdp starts and ends at voltage Vc.

[0096] In the following description, when a trapezoidal waveform Adp is supplied to the piezoelectric element 60, the predetermined amount of ink ejected is sometimes referred to as a medium amount, and when a trapezoidal waveform Bdp is supplied to the piezoelectric element 60, the amount of ink ejected less than the predetermined amount is sometimes referred to as a small amount. Furthermore, when a trapezoidal waveform Cdp is supplied to the piezoelectric element 60, the operation to vibrate the ink near the nozzle opening corresponding to the piezoelectric element 60 to prevent an increase in ink viscosity is sometimes referred to as micro-vibration. Note that the signal waveform of the drive signal COM shown in Figure 8 is just an example and is not limited to this; various combinations of waveforms may be used depending on the properties of the ejected ink and the material of the medium P to which the ink lands.

[0097] The drive signal selection circuit 200 then selects or deselects the trapezoidal waveforms Adp, Bdp, and Cdp included in the drive signal COM during a period tp that includes periods t1, t2, and t3. This allows the drive signal selection circuit 200 to control the amount of ink ejected from each of the nozzles 321 during period tp. In other words, the drive signal selection circuit 200 controls the dot size formed on the medium P during period tp. During this period tp, which includes periods t1, t2, and t3, dots of a predetermined size are formed on the medium P. This period tp, during which dots of a predetermined size are formed, corresponds to the dot formation period.

[0098] Next, the configuration and operation of the drive signal selection circuit 200, which generates the drive signal VOUT by selecting or deselecting the signal waveform included in the drive signal COM, will be described. Figure 9 is a diagram showing the configuration of the drive signal selection circuit 200. As shown in Figure 9, the drive signal selection circuit 200 has a selection control circuit 210 and a number of selection circuits 230 equal to the number of piezoelectric elements 60. In the following description, it will be assumed that the print head 22 has p piezoelectric elements 60. That is, the drive signal selection circuit 200 has p selection circuits 230.

[0099] The selection control circuit 210 receives the clock signal SCK, the print data signal SI, the latch signal LAT, and the change signal CH. Furthermore, the selection control circuit 210 is provided with a set of shift register (S / R) 212, latch circuit 214, and decoder 216, corresponding to each of the p piezoelectric elements 60. That is, the drive signal selection circuit 200 includes p shift registers 212, p latch circuits 214, and p decoders 216.

[0100] The print data signal SI is input to the selection control circuit 210 in synchronization with the clock signal SCK. The print data signal SI also serially includes 2 bits of print data [SIH,SIL] corresponding to each of the p piezoelectric elements 60 for selecting one of the following: "large dot LD", "medium dot MD", "small dot SD", and "no recording ND". The print data [SIH,SIL] included in the print data signal SI is held in p shift registers 212 corresponding to the p piezoelectric elements 60. Specifically, the p shift registers 212 corresponding to the piezoelectric elements 60 are connected in cascaded order, and the serially input print data signal SI is sequentially transferred to the subsequent shift registers 212 according to the clock signal SCK. When the print data [SIH,SIL] is held in the corresponding shift register 212, the clock signal SCK stops. As a result, the print data [SIH,SIL] included in the print data signal SI is held in the corresponding shift register 212. In Figure 9, the p shift registers 212 are labeled as stage 1, stage 2, ..., p in order from the upstream side where the print data signal SI is input, in order to distinguish them.

[0101] Each of the p latch circuits 214 simultaneously latches the print data [SIH,SIL] held in the corresponding shift register 212 on the rising edge of the latch signal LAT. The print data [SIH,SIL] latched by the latch circuits 214 is then input to the corresponding decoder 216. Figure 10 shows an example of the decoding content in the decoder 216. The decoder 216 outputs a selection signal S of a logic level defined by the input print data [SIH,SIL] for each of the periods t1, t2, and t3. For example, if print data [SIH,SIL]=[1,0] is input to the decoder 216, the decoder 216 outputs the logic level of the selection signal S as H, L, L levels for periods t1, t2, and t3.

[0102] The selection signal S output by the decoder 216 is input to the selection circuit 230. The selection circuit 230 is provided corresponding to each of the p piezoelectric elements 60. That is, the drive signal selection circuit 200 has the same number of selection circuits 230 as the number of p piezoelectric elements 60. Figure 11 is a diagram showing the configuration of the selection circuit 230. As shown in Figure 11, the selection circuit 230 includes an inverter 232 which is a NOT gate and a transfer gate 234.

[0103] The selection signal S is input to the positive control terminal of the transfer gate 234 that is not marked with a circle, and after its logic level is inverted by the inverter 232, it is also input to the negative control terminal of the transfer gate 234 that is marked with a circle. In addition, the drive signal COM is supplied to the input terminal of the transfer gate 234. The transfer gate 234 conducts between its input terminal and output terminal when a high-level selection signal S is input, and does not conduct between its input terminal and output terminal when a low-level selection signal S is input. That is, the transfer gate 234 outputs the signal waveform included in the drive signal COM from its output terminal when the logic level of the selection signal S is high, and does not output the signal waveform included in the drive signal COM from its output terminal when the logic level of the selection signal S is low. The drive signal selection circuit 200 outputs the signal output to the output terminal of the transfer gate 234, which is located in the selection circuit 230, as the drive signal VOUT.

[0104] Here, the operation of the drive signal selection circuit 200 will be explained using Figure 12. Figure 12 is a diagram illustrating the operation of the drive signal selection circuit 200. The print data signal SI is input to the selection control circuit 210 as a serial signal synchronized with the clock signal SCK. The print data signal SI is then sequentially transferred in p shift registers 212 corresponding to the p piezoelectric elements 60, in synchronization with the clock signal SCK. After the input of the clock signal SCK stops, the shift registers 212 hold the print data [SIH, SIL] corresponding to each of the p piezoelectric elements 60. The print data signal SI is input in the order corresponding to the p, ..., 2, and 1 stages of the piezoelectric elements 60 in the shift registers 212.

[0105] Then, when the latch signal LAT rises, each of the latch circuits 214 simultaneously latches the print data [SIH,SIL] held in the shift register 212. Note that LT1, LT2, ..., LTp shown in Figure 12 represent the print data [SIH,SIL] latched by the latch circuits 214 corresponding to the 1st, 2nd, ..., pth stage shift register 212.

[0106] The decoder 216 outputs the logic level of the selection signal S in each of the periods t1, t2, and t3, according to the size of the dots defined in the latched print data [SIH, SIL], as shown in Figure 12. The selection circuit 230 then generates the drive signal VOUT by selecting or deselecting the signal waveform included in the drive signal COM according to the logic level of the selection signal S output by the decoder 216.

[0107] Specifically, when the decoder 216 receives the print data [SIH,SIL]=[1,1], the decoder 216 sets the logic level of the selection signal S to H,H,L levels during periods t1, t2, and t3. As a result, the selection circuit 230 selects the trapezoidal waveform Adp during period t1, the trapezoidal waveform Bdp during period t2, and does not select the trapezoidal waveform Cdp during period t3. Consequently, the drive signal selection circuit 200 outputs the drive signal VOUT corresponding to the "large dot LD".

[0108] When the drive signal VOUT corresponding to the "large dot LD" is supplied to the piezoelectric element 60, a moderate amount of ink is ejected during period t1, a small amount of ink is ejected during period t2, and no ink is ejected during period t3. The ejected moderate and small amounts of ink then land on the medium P and combine, forming the "large dot LD" on the medium P.

[0109] Furthermore, when the print data [SIH,SIL]=[1,0] is input to the decoder 216, the decoder 216 sets the logic level of the selection signal S to H, L, L levels during periods t1, t2, and t3. As a result, the selection circuit 230 selects the trapezoidal waveform Adp during period t1, does not select the trapezoidal waveform Bdp during period t2, and does not select the trapezoidal waveform Cdp during period t3. Consequently, the drive signal selection circuit 200 outputs the drive signal VOUT corresponding to "Middle Dot MD".

[0110] When the drive signal VOUT corresponding to "medium dot MD" is supplied to the piezoelectric element 60, a moderate amount of ink is ejected during period t1, no ink is ejected during period t2, and no ink is ejected during period t3. The ejected moderate amount of ink then lands on the medium P, forming "medium dot MD" on the medium P.

[0111] Furthermore, when the decoder 216 receives the print data [SIH,SIL]=[0,1], the decoder 216 sets the logic level of the selection signal S to L, H, L levels during periods t1, t2, and t3. As a result, the selection circuit 230 does not select the trapezoidal waveform Adp during period t1, selects the trapezoidal waveform Bdp during period t2, and does not select the trapezoidal waveform Cdp during period t3. Consequently, the drive signal selection circuit 200 outputs the drive signal VOUT corresponding to "small dot SD".

[0112] When the drive signal VOUT corresponding to "small dot SD" is supplied to the piezoelectric element 60, no ink is ejected during period t1, a small amount of ink is ejected during period t2, and no ink is ejected during period t3. The ejected small amount of ink then lands on the medium P, forming "small dot SD" on the medium P.

[0113] Furthermore, when the decoder 216 receives the print data [SIH,SIL]=[0,0], the decoder 216 sets the logic level of the selection signal S to L,L,H levels during periods t1, t2, and t3. As a result, the selection circuit 230 does not select the trapezoidal waveform Adp during period t1, does not select the trapezoidal waveform Bdp during period t2, and selects the trapezoidal waveform Cdp during period t3. Consequently, the drive signal selection circuit 200 outputs the drive signal VOUT corresponding to "non-recorded ND".

[0114] When the drive signal VOUT corresponding to "non-recording ND" is supplied to the piezoelectric element 60, no ink is ejected during period t1, no ink is ejected during period t2, and no ink is ejected during period t3. Therefore, "non-recording ND" occurs, in which no dots are formed on the medium P. At this time, the corresponding piezoelectric element 60 receives the drive signal VOUT, which includes a trapezoidal waveform Cdp. Therefore, micro-vibrations are performed. As a result, the risk of increased ink viscosity near the opening of the corresponding nozzle 321 is reduced.

[0115] As described above, the drive signal selection circuit 200 generates the drive signal VOUT by selecting or deselecting the signal waveform of the drive signal COM output by the drive circuit 50, and outputs it to the corresponding piezoelectric element 60. In this case, the print head 22, which ejects ink based on the drive signal VOUT, can also be considered to eject ink based on the drive signal COM.

[0116] 1-5. Configuration of the temperature detection circuit Next, the configuration of the temperature detection circuit 250 will be described. Figure 13 shows an example of the configuration of the temperature detection circuit 250. As shown in Figure 13, the temperature detection circuit 250 has resistors 252 and 254. Resistor 254 also includes the aforementioned resistor wiring 401 and measuring lead electrodes 393a and 393b. That is, at least resistor 254 of the temperature detection circuit 250 is provided on the print head 22. Note that the entirety of the temperature detection circuit 250 may also be provided on the print head 22.

[0117] A constant voltage signal VDD is supplied to one end of resistor 252. The other end of resistor 252 is electrically connected to one end of resistor 254, which contains a measuring lead electrode 393a. The other end of resistor 254, which contains a measuring lead electrode 393b, is supplied with ground potential. The temperature detection circuit 250 outputs the voltage value generated at the connection point between the other end of resistor 252 and one end of resistor 254 as the head temperature signal TC. In other words, the temperature detection circuit 250 outputs a signal as the head temperature signal TC that is obtained by dividing the voltage signal VDD by the resistance value of resistor 252 and the resistance value of resistor wiring 401.

[0118] As described above, the resistance value of the resistor wiring 401 is the temperature of the print head 22, and changes according to the temperature of the pressure chamber 312. In other words, the resistor 254, including the resistor wiring 401, functions as a thermistor element whose resistance value changes with temperature. And because the resistance value of the resistor wiring 401 is the temperature of the print head 22, and changes according to the temperature of the pressure chamber 312, the voltage value of the head temperature signal TC output by the temperature detection circuit 250 is also the temperature of the print head 22, and changes according to the temperature of the pressure chamber 312. In other words, the temperature detection circuit 250 outputs a head temperature signal TC, which is the temperature of the print head 22, and whose voltage value changes according to the temperature of the pressure chamber 312.

[0119] In this embodiment, the temperature detection circuit 250 has been described as including a resistor wiring 401 and measuring lead electrodes 393a and 393b among the resistors 252 and 254 that divide the voltage signal VDD. However, the resistor 252 on the high-potential side may also be configured to include a resistor wiring 401 and measuring lead electrodes 393a and 393b. Furthermore, the temperature detection circuit 250 may be configured to include multiple resistor elements in addition to resistors 252 and 254.

[0120] 1-6. Configuration of the Temperature Information Output Circuit Next, the configuration and operation of the temperature information output circuit 26 will be described. Figure 14 shows an example of the configuration of the temperature information output circuit 26. Based on the temperature acquisition request signal TD input from the control circuit 100, the temperature information output circuit 26 selects at least one of the head temperature signals TC1 to TCn input from each of the print heads 22-1 to 22-n, and acquires the selected head temperature signal TC at the timing specified by the drive signal COM. Then, based on the acquired head temperature signal TC and the unit temperature signal TH input from the temperature detection circuit 28, the temperature information output circuit 26 generates a temperature information signal TI corresponding to the temperature of the print head 22 and outputs it to the control circuit 100.

[0121] As shown in Figure 14, the temperature information output circuit 26 includes a control circuit 500, a multiplexer 510, amplification circuits 520, 550, A / D converters 530, 560, a memory circuit 570, a comparator circuit 580, and a timing control circuit 590.

[0122] The multiplexer 510 receives the head temperature signals TC1 to TCn output by each of the print heads 22-1 to 22-n. The multiplexer 510 also receives the select signal Sel output by the control circuit 500. Based on the input select signal Sel, the multiplexer 510 selects one of the head temperature signals TC1 to TCn and outputs it as the selected temperature signal STC.

[0123] The amplification circuit 520 receives the selected temperature signal STC output by the multiplexer 510. The amplification circuit 520 generates and outputs the amplification head temperature signal ATC by amplifying the voltage value of the input selected temperature signal STC.

[0124] The A / D converter 530 receives the amplified head temperature signal ATC output by the amplification circuit 520 and the enable signal EN1 output by the control circuit 500. When the enable signal EN1, which enables operation, is input to the A / D converter 530, it acquires the voltage value of the amplified head temperature signal ATC, generates a digital signal corresponding to the acquired voltage value, and outputs it to the control circuit 500 as digital temperature information dtc. In other words, when the enable signal EN1, which enables operation, is input to the A / D converter 530, it generates digital temperature information dtc corresponding to the voltage value of the amplified head temperature signal ATC, which is amplified by the amplification circuit 520 from the head temperature signal TC selected by the multiplexer 510, and outputs it to the control circuit 500. To put it another way, when the enable signal EN1, which enables operation, is input to the A / D converter 530, it generates digital temperature information dtc corresponding to the temperature of the print head 22 corresponding to the head temperature signal TC selected by the multiplexer 510, and outputs it to the control circuit 500.

[0125] In the following explanation, it is assumed that the A / D converter 530 becomes operational on the rising edge of the enable signal EN1. That is, the A / D converter 530 generates digital temperature information dtc by converting the input amplifier head temperature signal ATC into a digital signal at the rising edge of the enable signal EN1, and outputs this to the control circuit 500. Alternatively, the A / D converter 530 may become operational on the falling edge of the enable signal EN1. In this case, the A / D converter 530 outputs digital temperature information dtc, which is obtained by converting the input amplifier head temperature signal ATC into a digital signal at the falling edge of the enable signal EN1, to the control circuit 500.

[0126] The unit temperature signal TH output by the temperature detection circuit 28 is input to the amplification circuit 550. The amplification circuit 520 amplifies the voltage value of the input unit temperature signal TH to generate and output the amplified unit temperature signal ATH.

[0127] The A / D converter 560 receives the amplification unit temperature signal ATH output by the amplification circuit 520 and the enable signal EN2 output by the control circuit 500. When the enable signal EN2, which enables operation, is input to the A / D converter 560, it acquires the voltage value of the amplification unit temperature signal ATH, generates a digital signal corresponding to the acquired voltage value, and outputs it to the control circuit 500 as digital temperature information dth. In other words, when the enable signal EN2, which enables operation, is input to the A / D converter 560, it generates digital temperature information dth corresponding to the temperature detected by the temperature detection circuit 28 and outputs it to the control circuit 500.

[0128] In the following explanation, it is assumed that the A / D converter 560 becomes operational on the rising edge of the enable signal EN2. That is, the A / D converter 560 generates digital temperature information dth by converting the input amplification unit temperature signal ATH into a digital signal at the rising edge of the enable signal EN2, and outputs this to the control circuit 500. Alternatively, the A / D converter 560 may become operational on the falling edge of the enable signal EN2. In this case, the A / D converter 560 outputs digital temperature information dth, which is obtained by converting the input amplification unit temperature signal ATH into a digital signal at the falling edge of the enable signal EN2, to the control circuit 500.

[0129] The comparator circuit 580 receives the drive signal COM as input. The comparator circuit 580 compares the voltage value of the input drive signal COM with a predetermined voltage value and outputs a logical OR signal Vcr whose logic level changes according to the comparison result.

[0130] The timing control circuit 590 receives the OR signal Vcr output by the comparator circuit 580 and the clock signal CK output by the control circuit 500. The timing control circuit 590 acquires the logic level of the OR signal Vcr in synchronization with the clock signal CK and generates a timing control signal Tgi with a logic level corresponding to the acquired OR signal Vcr. The timing control circuit 590 then outputs the generated timing control signal Tgi to the control circuit 500.

[0131] Here, we will describe the details of the comparator circuit 580 and the timing control circuit 590. Figure 15 shows an example of the configuration of the comparator circuit 580 and the timing control circuit 590.

[0132] The comparator circuit 580 includes comparators 581 and 582, resistors 584 and 586, and an OR circuit 583. A drive signal COM is input to one end of resistor 584. The other end of resistor 584 is electrically connected to one end of resistor 586. The other end of resistor 586 is supplied with ground potential. The connection point between the other end of resistor 584 and one end of resistor 586 is electrically connected to the + input terminal of comparator 581 and the - input terminal of comparator 582.

[0133] Furthermore, a threshold voltage signal Vth_Hi is input to the negative input terminal of comparator 581. Comparator 581 generates a comparison result signal Co1, which is high level when the voltage value at the positive input terminal is greater than or equal to the voltage value at the negative input terminal, and low level when the voltage value at the positive input terminal is less than the voltage value at the negative input terminal, and outputs this signal from its output terminal. Similarly, a threshold voltage signal Vth_Low is input to the positive input terminal of comparator 582. Comparator 582 generates a comparison result signal Co2, which is high level when the voltage value at the positive input terminal is greater than or equal to the voltage value at the negative input terminal, and low level when the voltage value at the positive input terminal is less than the voltage value at the negative input terminal, and outputs this signal from its output terminal. Although not shown in the figure, the threshold voltage signals Vth_Hi and Vth_Low are generated, for example, by a threshold voltage signal generator in the liquid discharge device 1 and supplied to comparators 581 and 582.

[0134] The OR circuit 583 is electrically connected to comparators 581 and 582, and receives comparison result signals Co1 and Co2 as inputs. Depending on the logic levels of comparison result signals Co1 and Co2, it outputs a logical OR signal Vcr. Specifically, if both comparison result signals Co1 and Co2 are at a high level, it outputs a logical OR signal Vcr at a high level. If both comparison result signals Co1 and Co2 are at a low level, it outputs a logical OR signal Vcr at a low level. If comparison result signal Co1 is at a high level and comparison result signal Co2 is at a low level, it outputs a logical OR signal Vcr at a high level.

[0135] In the comparator circuit 580 configured as described above, resistors 584 and 586 attenuate the drive signal COM by dividing its voltage. Comparator 581 compares the voltage value of the attenuated drive signal COM with the voltage value of the threshold voltage signal Vth_Hi and outputs a comparison result signal Co1 according to the comparison result. Comparator 582 compares the voltage value of the attenuated drive signal COM with the voltage value of the threshold voltage signal Vth_Low and outputs a comparison result signal Co2 according to the comparison result. In other words, resistors 584 and 586 define the attenuation rate of the drive signal COM. This sets the voltage value of the drive signal COM at which the logic levels of the comparison result signals Co1 and Co2 output by comparators 581 and 582 are switched. Here, in the following explanation, the predetermined voltage values ​​of the drive signal COM at which the logic level of the logical OR signal Vcr output by the comparator circuit 580 is switched are referred to as switching voltages Vch1 and Vch2. It is assumed that switching voltage Vch1 is a voltage value greater than switching voltage Vch2.

[0136] In other words, the comparator circuit 580 compares the voltage value of the drive signal COM with the switching voltages Vch1 and Vch2, and outputs a logical OR signal Vcr at a high level if the voltage value of the drive signal COM is greater than or equal to the voltage values ​​of the switching voltages Vch1 and Vch2. Also, if the voltage value of the drive signal COM is less than the switching voltage Vch1 and greater than or equal to the voltage value of the switching voltage Vch2, it outputs a logical OR signal Vcr at a low level. Furthermore, if the voltage value of the drive signal COM is less than the voltage values ​​of the switching voltages Vch1 and Vch2, it outputs a logical OR signal Vcr at a high level. Note that the comparator circuit 580 may include multiple resistor elements that divide the threshold voltage signals Vth_Hi and Vth_Low in addition to resistors 584 and 586. Also, if comparators 581 and 582 can operate without attenuating the voltage value of the drive signal COM, the comparator circuit 580 does not need to include resistors 584 and 586. Furthermore, the comparison circuit 580 is not limited to comparators 581 and 582, but may also be composed of operational amplifiers.

[0137] The timing control circuit 590 includes D-type flip-flops 592 and 594 and an OR circuit 596. The data input terminal D1 of the D-type flip-flop 592 is input to the OR signal Vcr output by the comparator circuit 580. The clock input terminal CLK1 of the D-type flip-flop 592 is input to the clock signal CK output by the control circuit 500. Then, at the rising edge of the clock signal CK input to the clock input terminal CLK1, the D-type flip-flop 592 generates a data signal Do1 corresponding to the logic level of the OR signal Vcr input to the data input terminal D1 and outputs it from the data output terminal Q1.

[0138] The data input terminal D2 of the D-type flip-flop 594 receives the OR signal Vcr output by the comparator circuit 580. The clock input terminal CLK2 of the D-type flip-flop 594 receives a signal with the logic level of the clock signal CK output by the control circuit 500 inverted. The D-type flip-flop 594 then generates a data signal Do2 corresponding to the logic level of the OR signal Vcr input to the data input terminal D2 at the rising edge of the inverted logic level of the clock signal CK input to the clock input terminal CLK2, that is, at the falling edge of the logic level of the clock signal CK output by the control circuit 500, and outputs it from the data output terminal Q2.

[0139] The OR circuit 596 receives data signal Do1 output by D-type flip-flop 592 and data signal Do2 output by D-type flip-flop 594. The OR circuit 596 outputs a timing control signal Tgi that is low level when the logic levels of both input data signals Do1 and Do2 are low, and high level when the logic level of at least one of the input data signals Do1 and Do2 is high. This timing control signal Tgi output by the OR circuit 596 is output from the timing control circuit 590 and input to the control circuit 500.

[0140] As described above, in the timing control circuit 590 of this embodiment, the D-type flip-flop 592 outputs a high-level data signal Do1 when the OR signal Vcr input to the data input terminal D1 is at a high level on the rising edge of the clock signal CK, and outputs a low-level data signal Do1 when the OR signal Vcr input to the data input terminal D1 is at a low level on the rising edge of the clock signal CK. On the other hand, the D-type flip-flop 594 outputs a high-level data signal Do2 when the OR signal Vcr input to the data input terminal D2 is at a high level on the falling edge of the clock signal CK, and outputs a low-level data signal Do2 when the OR signal Vcr input to the data input terminal D2 is at a low level on the falling edge of the clock signal CK.

[0141] Therefore, the OR circuit 596 generates and outputs an L-level timing control signal Tgi when an L-level OR signal Vcr is input to the timing control circuit 590 on the rising edge of the clock signal CK, and when an L-level OR signal Vcr is input to the timing control circuit 590 immediately afterward on the falling edge of the clock signal CK. Alternatively, the OR circuit 596 generates and outputs an L-level timing control signal Tgi when an L-level OR signal Vcr is input to the timing control circuit 590 on the falling edge of the clock signal CK, and when an L-level OR signal Vcr is input to the timing control circuit 590 immediately afterward on the rising edge of the clock signal CK. In other words, if an L-level OR signal Vcr is input to both the rising edge and the falling edge of the clock signal CK, the timing control circuit 590 determines that an L-level OR signal Vcr has been continuously input to the timing control circuit 590 for the period from the falling edge to the rising edge of the clock signal CK, or for the period from the rising edge to the falling edge of the clock signal CK, and outputs an L-level timing control signal Tgi.

[0142] As described above, the timing control circuit 590 of this embodiment includes a D-type flip-flop 592 and a D-type flip-flop 594 to which a logical OR signal Vcr is input, and an OR circuit 596 to which a data signal Do1 output by the D-type flip-flop 592 and a data signal Do2 output by the D-type flip-flop 594 are input. The D-type flip-flop 592 outputs a data signal Do1 corresponding to the logic level of the logical OR signal Vcr at the rising edge of the clock signal CK, the D-type flip-flop 594 outputs a data signal Do2 corresponding to the logic level of the logical OR signal Vcr at the falling edge of the clock signal CK, and the OR circuit 596 outputs a timing control signal Tgi corresponding to the logic levels of the data signal Do1 and the data signal Do2.

[0143] Returning to Figure 14, the control circuit 500 outputs a select signal Sel and a clock signal CK in response to the temperature acquisition request signal TD input from the control circuit 100, and also outputs enable signals EN1 and EN2 in response to the temperature acquisition request signal TD input from the control circuit 100 and the timing control signal Tgi input from the timing control circuit 590. In this way, the control circuit 500 controls the operation of the various components included in the temperature information output circuit 26. The control circuit 500 also acquires the input digital temperature information dtc and generates a temperature information signal TI corresponding to the acquired digital temperature information dtc. The control circuit 500 then outputs the generated temperature information signal TI from the temperature information output circuit 26. This temperature information signal TI is input to the control circuit 100.

[0144] Specifically, the control circuit 500 includes a request analysis unit 501, a clock signal output unit 502, a temperature information output unit 503, a correction value calculation unit 504, and a memory control unit 505.

[0145] The request analysis unit 501 acquires and analyzes the temperature acquisition request signal TD input to the control circuit 500. The control circuit 500 generates a select signal Sel according to the analysis result of the request analysis unit 501 and outputs it to the multiplexer 510. As a result, the multiplexer 510 selects the head temperature signal TC that is selected by the select signal Sel and is specified by the temperature acquisition request signal TD. Therefore, the amplification circuit 520 generates an amplified head temperature signal ATC by amplifying the head temperature signal TC specified by the temperature acquisition request signal TD and outputs it to the A / D converter 530.

[0146] The clock signal output unit 502 generates a clock signal CK by dividing or multiplying the oscillation signal output by an oscillation circuit (not shown). The control circuit 500 outputs the generated clock signal CK. At this time, the clock signal output unit 502 may be controlled to generate the clock signal CK or not depending on the analysis result of the temperature acquisition request signal TD in the request analysis unit 501, and the period and frequency of the generated clock signal CK may also be controlled. Of course, the clock signal output unit 502 may generate a clock signal CK with a predetermined period and frequency regardless of the analysis result of the temperature acquisition request signal TD in the request analysis unit 501.

[0147] In this embodiment, at a timing defined by the timing control signal Tgi after a temperature acquisition request signal TD requesting the acquisition of the temperature of the print head 22 is input to the control circuit 500, and at a timing where the logic level of the timing control signal Tgi becomes L level, the temperature information output unit 503 outputs an enable signal EN1 to effectively control the operation of the A / D converter 530. As a result, the A / D converter 530 acquires the amplified head temperature signal ATC output by the amplified circuit 520, converts it into a digital signal, and outputs it to the control circuit 500 as digital temperature information dtc. At this time, the temperature information output unit 503 acquires the digital temperature information dtc output by the A / D converter 530 and generates a temperature information signal TI based on the acquired digital temperature information dtc. The control circuit 500 outputs the temperature information signal TI generated by the temperature information output unit 503 to the control circuit 100.

[0148] In other words, the temperature information output unit 503 generates a temperature information signal TI based on digital temperature information dtc corresponding to the voltage value of the head temperature signal TC output by the print head 22, at the timing when the logic level of the timing control signal Tgi becomes L level, and the temperature information signal TI corresponds to the temperature of the print head 22 corresponding to the head temperature signal TC specified by the temperature acquisition request signal TD. The control circuit 500 then outputs the temperature information signal TI generated by the temperature information output unit 503 to the control circuit 100.

[0149] The correction value calculation unit 504 calculates a correction value to correct the temperature information signal TI output by the control circuit 500. For example, at a predetermined timing after the temperature acquisition request signal TD, which includes a request for calculation of the correction value, is input from the control circuit 100, the correction value calculation unit 504 outputs an enable signal EN1 that effectively controls the operation of the A / D converter 530 and an enable signal EN2 that effectively controls the operation of the A / D converter 560. As a result, the A / D converter 530 acquires the amplification head temperature signal ATC output by the amplification circuit 520, converts it into a digital signal, and outputs it as digital temperature information dtc. The A / D converter 560 acquires the amplification unit temperature signal ATH output by the amplification circuit 550, converts it into a digital signal, and outputs it as digital temperature information dth. The correction value calculation unit 504 then acquires the input digital temperature information dtc and digital temperature information dth, and calculates a correction value based on the acquired digital temperature information dtc and digital temperature information dth.

[0150] Specifically, when the control circuit 500 receives a temperature acquisition request signal TD from the control circuit 100, which includes a request to calculate a correction value corresponding to the print head 22, the request analysis unit 501 outputs a select signal Sel to select the corresponding print head 22. Subsequently, the correction value calculation unit 504 outputs an enable signal EN1 to effectively control the operation of the A / D converter 530 and an enable signal EN2 to effectively control the operation of the A / D converter 560 almost simultaneously. As a result, the correction value calculation unit 504 acquires digital temperature information dtc and digital temperature information dth at the same time. Based on the difference between the acquired digital temperature information dtc and digital temperature information dth, the correction value calculation unit 504 calculates a correction value corresponding to the print head 22. At this time, the correction value calculation unit 504 may individually calculate n correction values ​​corresponding to each of the print heads 22-1 to 22-n. The temperature information output unit 503 corrects the acquired digital temperature information dtc using the correction value calculated by the correction value calculation unit 504, and generates a temperature information signal TI based on the corrected digital temperature information dtc. This improves the accuracy of the temperature information signal TI output by the control circuit 500.

[0151] The memory control unit 505 generates a memory control signal MA for accessing the memory circuit 570 and outputs it to the memory circuit 570, and also acquires a memory read signal MR output by the memory circuit 570 in response to the memory control signal MA. Specifically, the memory control unit 505 generates a memory control signal MA for storing information such as correction values ​​and outputs it to the memory circuit 570. Then, the memory control unit 505 generates a memory control signal MA for reading the information such as correction values ​​stored in the memory circuit 570 and outputs it to the memory circuit 570.

[0152] The memory circuit 570 stores various information, including correction values, in response to the input memory control signal MA, reads out the correction values ​​and other information, and outputs a memory read signal MR containing the read information to the control circuit 500. Such a memory circuit 570 is configured to include non-volatile memory such as ROM or flash memory.

[0153] As described above, the temperature information output circuit 26 includes a control circuit 500 that acquires digital temperature information dtc corresponding to the temperature of the print head 22 from the head temperature signal TC, and a timing control circuit 590 that controls the timing at which the control circuit 500 acquires the digital temperature information dtc. Such a temperature information output circuit 26 is preferably configured as an integrated circuit, for example. This makes it possible to reduce the mounting area of ​​the temperature information output circuit 26 in the head unit 20, and as a result, the head unit 20 can be miniaturized. In this case, the integrated circuit constituting the temperature information output circuit 26 is not limited to one but may be multiple. Of course, the temperature information output circuit 26 may be configured to include multiple circuit elements in addition to the integrated circuit.

[0154] 1-7. Temperature detection timing in the temperature information output circuit In the liquid ejection device 1 and head unit 20, the physical properties of the ink ejected from the nozzle 321 change with temperature, such as viscosity. Such changes in the physical properties of the ink significantly contribute to the ink ejection accuracy. Therefore, the liquid ejection device 1 and head unit 20 acquire the temperature of the ink ejected from the nozzle 321, which is the temperature of the ink stored in the pressure chamber 312 communicating with the nozzle 321, and correct various signals that control the operation of the liquid ejection device 1 and head unit 20 according to the acquired ink temperature. This reduces the risk of a decrease in ink ejection accuracy even when the ink temperature changes.

[0155] In particular, in the liquid ejection device 1 and head unit 20 of this embodiment, the temperature detection circuit 250 for detecting the temperature of the print head 22 includes a resistance wiring 401 whose resistance value changes with temperature. The resistance wiring 401 is located near the pressure chamber 312 and is formed on a diaphragm 350 that seals the opening on the -Z side surface of the pressure chamber substrate 310 in which the pressure chamber 312 is formed. As a result, the temperature detection circuit 250 can detect the temperature of the ink stored in the pressure chamber 312 in the vicinity of the pressure chamber 312, and can detect the temperature of the ink stored in the pressure chamber 312 with greater accuracy. Consequently, in the liquid ejection device 1 and head unit 20 of this embodiment, it is possible to more appropriately correct various signals that control the operation of the liquid ejection device 1 and head unit 20 according to the temperature of the ink stored in the pressure chamber 312, and the risk of a decrease in ink ejection accuracy can be further reduced even when the ink temperature changes.

[0156] On the other hand, because the resistor wiring 401 included in the temperature detection circuit 250 is located near the pressure chamber 312 where the ink is stored, the following problems may become significantly more pronounced.

[0157] From the viewpoint of improving the quality of the image formed on the medium P, the print head 22 has several hundred or more nozzles 321 arranged at high density. Therefore, the print head 22 has several hundred or more piezoelectric elements 60 corresponding to several hundred or more nozzles 321, and these several hundred or more piezoelectric elements 60 are arranged at high density on the diaphragm 350. Consequently, the signal wiring through which the drive signal VOUT supplied to each piezoelectric element 60 in the print head 22 propagates is densely arranged on the diaphragm 350. If a resistor wiring 401 is placed on such a diaphragm 350, the resistor wiring 401 will be placed near the signal wiring through which the drive signal VOUT propagates, increasing the likelihood that noise generated due to changes in the voltage value of the drive signal VOUT will contribute to the resistor wiring 401. Furthermore, if noise generated due to changes in the voltage of the drive signal VOUT contributes to the resistor wiring 401, the accuracy of the head temperature signal TC output by the temperature detection circuit 250 including the resistor wiring 401 will decrease, and the accuracy of temperature detection in the pressure chamber 312 will decrease.

[0158] Furthermore, when the piezoelectric element 60 is driven by the drive signal VOUT, the diaphragm 350 on which the resistor wiring 401 is located is displaced as the piezoelectric element 60 is driven. This displacement of the diaphragm 350 may cause the impedance of the resistor wiring 401 located on the diaphragm 350 to change. If the impedance of the resistor wiring 401 located on the diaphragm 350 changes, the accuracy of the head temperature signal TC output by the temperature detection circuit 250, which includes the resistor wiring 401, will decrease, and the accuracy of detecting the temperature of the pressure chamber 312 will decrease.

[0159] Furthermore, as described above, the print head 22 applies pressure to the ink contained in the pressure chamber 312 by changing the volume of the pressure chamber 312, and ejects the ink from the nozzle 321. In a print head 22 with such a structure, the temperature of the ink stored in the pressure chamber 312 may change instantaneously due to the pressure change in the pressure chamber 312 that occurs when the ink is ejected. When the temperature detection circuit 250, which includes the resistor wiring 401, detects this instantaneous temperature change, it may detect a temperature different from the temperature that should be detected, and this may be superimposed as noise on the head temperature signal TC output by the temperature detection circuit 250. If the instantaneous temperature change of the ink stored in the pressure chamber 312 is superimposed as noise on the head temperature signal TC, the accuracy of the head temperature signal TC output by the temperature detection circuit 250 will decrease, and the accuracy of detecting the temperature of the pressure chamber 312 will decrease.

[0160] To address this problem, in the liquid dispensing device 1 of this embodiment, the timing control circuit 590 of the temperature information output circuit 26 controls the optimal acquisition timing of the head temperature signal TC, thereby improving the accuracy of the digital temperature information dtc based on the head temperature signal TC acquired by the control circuit 500, and improving the reliability of the temperature information signal TI based on the digital temperature information dtc. As a result, the risk of a decrease in the detection accuracy of the temperature of the pressure chamber 312 detected by the temperature detection circuit 250 is reduced.

[0161] To explain the timing for acquiring the temperature of the print head 22, we will first describe an example of the operation of the liquid ejection device 1 in this embodiment, and then describe an example of the timing for acquiring the temperature of the print head 22 in the operation of the liquid ejection device 1. Figure 16 is a diagram showing an example of the operation of the liquid ejection device 1 in this embodiment.

[0162] As described above, the liquid ejection device 1 of this embodiment is a serial printing inkjet printer, and immediately before time t10, the carriage 21, which moves back and forth along the scanning direction, is in the home position and stopped. At this time, the control circuit 100 outputs a control signal Ctrl-C to stop the carriage 21 on which the print head 22 is mounted, and also performs an inversion process to reverse the scanning direction of the carriage 21, and the drive circuit 50 outputs a drive signal COM with a constant voltage value of voltage Vb.

[0163] Then, at time t10, once the reversal process of the scanning direction of the carriage 21 is complete, the drive circuit 50 starts outputting a drive signal COM whose voltage value is constant at voltage Vc. Also, at time t10, when the drive circuit 50 starts outputting the drive signal COM whose voltage value is constant at voltage Vc, the control circuit 100 outputs a print data signal SI that controls the logic level of the selection signal S to H level in order to control all selection circuits 230 to conduct. As a result, each electrode 360 ​​of the multiple piezoelectric elements 60 of the print head 22 is supplied with a drive signal VOUT based on the drive signal COM output by the drive circuit 50, and the drive signal VOUT whose voltage value changes toward voltage Vc.

[0164] Subsequently, when the voltage value of the drive signal COM output by the drive circuit 50 becomes constant at voltage Vc, a drive signal VOUT with a voltage value of voltage Vc is supplied to the electrode 360 ​​of the piezoelectric element 60. Then, after the drive signal VOUT with a voltage value of voltage Vc is supplied to the electrode 360 ​​of the piezoelectric element 60, the control circuit 100 outputs a print data signal SI that controls the logic level of the selection signal S to L level in order to control all selection circuits 230 to non-conductive state. As a result, the selection circuits 230 are controlled to non-conductive state. At this time, the voltage value of the electrode 360 ​​of the piezoelectric element 60 is maintained at voltage Vc by the capacitive component of the piezoelectric element 60.

[0165] Then, at time t20, after the voltage value of the drive signal COM output by the drive circuit 50 has become constant at voltage Vc, the control circuit 100 outputs a control signal Ctrl-C to move the carriage 21 on which the print head 22 is mounted along the forward direction Fw from the home position side to the non-home position side. This initiates the movement of the carriage 21 along the scanning axis in the forward direction Fw.

[0166] At time t30, after the carriage 21 has started moving forward Fw along the scanning axis, the drive circuit 50 starts outputting a drive signal COM consisting of consecutive trapezoidal waveforms Adp, Bdp, and Cdp as shown in Figure 8. Then, at time t40, when the scanning position of the carriage 21 reaches the printing area on the medium P where an image is formed, the control circuit 100 outputs a print data signal SI and a clock signal SCK corresponding to the image information signal input from an external device, and a change signal CH and a latch signal LAT corresponding to the scanning position of the carriage 21. Consequently, the selection control circuit 210 outputs a logic level selection signal S corresponding to each of the multiple piezoelectric elements 60, and the selection circuit 230 outputs a drive signal VOUT based on the drive signal COM. As a result, an image corresponding to the image information signal is formed on the medium P. That is, a printing process is performed in which ink is ejected onto the medium P. Here, the printing area is an area in which the print head 22 can eject ink onto the medium P, and includes an area in which at least a portion of the print head 22 is positioned facing the medium P along the ink ejection direction.

[0167] At time t50, when the printing process in the forward direction Fw along the scanning axis is completed, the control circuit 100 outputs a print data signal SI that controls the logic level of the selection signal S to L level in order to control all selection circuits 230 to deconduct. As a result, the selection circuits 230 are controlled to deconduct. At this time, the voltage value of the electrode 360 ​​of the piezoelectric element 60 is held at voltage Vc by the capacitive component of the piezoelectric element 60. Subsequently, at time t60, the drive circuit 50 stops outputting a drive signal COM consisting of consecutive trapezoidal waveforms Adp, Bdp, and Cdp, and starts outputting a drive signal COM with a constant voltage value of voltage Vc.

[0168] Then, at time t70, after the voltage value of the drive signal COM output by the drive circuit 50 has become constant at voltage Vc, when the scanning position of the carriage 21 reaches the stop area on the opposite side of the home position, the control circuit 100 outputs a control signal Ctrl-C to stop the carriage 21 equipped with the print head 22. As a result, the carriage 21 stops.

[0169] At time t80, after the carriage 21 has stopped, the drive circuit 50 begins outputting a drive signal COM with a constant voltage value of voltage Vb. Also at time t80, when the drive circuit 50 begins outputting the drive signal COM with a constant voltage value of voltage Vb, the control circuit 100 outputs a print data signal SI that controls the logic level of the selection signal S to H level in order to control all selection circuits 230 to conduct. As a result, each electrode 360 ​​of the multiple piezoelectric elements 60 of the print head 22 is supplied with a drive signal VOUT based on the drive signal COM output by the drive circuit 50, where the voltage value of the drive signal VOUT changes toward voltage Vb.

[0170] After the voltage value of the drive signal VOUT supplied to the electrode 360 ​​of the piezoelectric element 60 becomes constant at voltage Vb, the control circuit 100 outputs a print data signal SI that controls the logic level of the selection signal S to L level in order to control all selection circuits 230 to non-conductive. As a result, the selection circuits 230 are controlled to non-conductive. At this time, the voltage value of the electrode 360 ​​of the piezoelectric element 60 is maintained at voltage Vb by the capacitive component of the piezoelectric element 60. Subsequently, the liquid dispensing device 1 waits for a period of time until the reversal process is completed in which the scanning direction of the carriage 21 is reversed from the non-home position side to the home position side Rv, while the drive circuit 50 continues to output a drive signal COM with a constant voltage value of voltage Vb.

[0171] Furthermore, at a predetermined timing within the waiting period until the reversal process of the scanning direction of the carriage 21 is completed, the drive circuit 50 outputs a drive signal COM including a micro-vibration waveform obs. At this time, the control circuit 100 outputs a print data signal SI that controls the logic level of the selection signal S to an H level in order to control all selection circuits 230 to conduct. As a result, the drive signal VOUT including the micro-vibration waveform obs is supplied to the electrodes 360 of the piezoelectric element 60. Consequently, the risk of ink adhering near the nozzle 321 during the waiting period is reduced, and the risk of the ink viscosity near the nozzle 321 increasing is also reduced. Note that the drive signal VOUT including the micro-vibration waveform obs is not limited to being supplied to all piezoelectric elements 60 of the print head 22, but may be supplied to only some of the piezoelectric elements 60 of the print head 22. Also, the micro-vibration caused by the drive signal VOUT including the micro-vibration waveform obs may be performed multiple times during the waiting period.

[0172] At time t90, once the reversal process of the scanning direction of the carriage 21 is complete, the drive circuit 50 starts outputting a drive signal COM whose voltage value is constant at voltage Vc. Also at time t90, when the drive circuit 50 starts outputting the drive signal COM whose voltage value is constant at voltage Vc, the control circuit 100 outputs a print data signal SI that controls the logic level of the selection signal S to H level in order to control all selection circuits 230 to conduct. As a result, each electrode 360 ​​of the multiple piezoelectric elements 60 of the print head 22 is supplied with a drive signal VOUT based on the drive signal COM output by the drive circuit 50, where the voltage value changes toward voltage Vc.

[0173] Subsequently, when the voltage value of the drive signal COM output by the drive circuit 50 becomes constant at voltage Vc, a drive signal VOUT with a voltage value of voltage Vc is supplied to the electrode 360 ​​of the piezoelectric element 60. Then, after the drive signal VOUT with a voltage value of voltage Vc is supplied to the electrode 360 ​​of the piezoelectric element 60, the control circuit 100 outputs a print data signal SI that controls the logic level of the selection signal S to L level in order to control all selection circuits 230 to non-conductive state. As a result, the selection circuits 230 are controlled to non-conductive state. At this time, the voltage value of the electrode 360 ​​of the piezoelectric element 60 is maintained at voltage Vc by the capacitive component of the piezoelectric element 60.

[0174] Then, at time t100, after the voltage value of the drive signal COM output by the drive circuit 50 has become constant at voltage Vc, the control circuit 100 outputs a control signal Ctrl-C to move the carriage 21 on which the print head 22 is mounted along the reverse direction Rv from the non-home position side to the home position side. This initiates the movement of the carriage 21 along the scan axis in the reverse direction Rv.

[0175] At time t110, after the carriage 21 has started moving in the reverse direction Rv along the scanning axis, the drive circuit 50 starts outputting a drive signal COM consisting of consecutive trapezoidal waveforms Adp, Bdp, and Cdp. Then, at time t120, when the scanning position of the carriage 21 reaches the printing area on the medium P where an image is formed, the control circuit 100 outputs a print data signal SI and a clock signal SCK corresponding to the image information signal input from an external device, and a change signal CH and a latch signal LAT corresponding to the scanning position of the carriage 21. As a result, the selection control circuit 210 outputs a logic level selection signal S corresponding to each of the multiple piezoelectric elements 60, and the selection circuit 230 outputs a drive signal VOUT based on the drive signal COM. As a result, an image corresponding to the image information signal is formed on the medium P, that is, the printing process is executed.

[0176] At time t130, when the printing process in the reverse direction Rv along the scanning axis is completed, the control circuit 100 outputs a print data signal SI that controls the logic level of the selection signal S to L level in order to control all selection circuits 230 to deconduct. As a result, the selection circuits 230 are controlled to deconduct. At this time, the voltage value of the electrode 360 ​​of the piezoelectric element 60 is held at voltage Vc by the capacitive component of the piezoelectric element 60. Subsequently, at time t140, the drive circuit 50 stops outputting a drive signal COM consisting of consecutive trapezoidal waveforms Adp, Bdp, and Cdp, and starts outputting a drive signal COM with a constant voltage value of voltage Vc.

[0177] Then, at time t150, after the voltage value of the drive signal COM output by the drive circuit 50 has become constant at voltage Vc, when the scanning position of the carriage 21 reaches the stop area on the home position side, the control circuit 100 outputs a control signal Ctrl-C to stop the carriage 21 equipped with the print head 22. As a result, the carriage 21 stops.

[0178] At time t160, after the carriage 21 has stopped, the drive circuit 50 begins outputting a drive signal COM with a constant voltage value of voltage Vb. Also at time t160, when the drive circuit 50 begins outputting the drive signal COM with a constant voltage value of voltage Vb, the control circuit 100 outputs a print data signal SI that controls the logic level of the selection signal S to H level in order to control all selection circuits 230 to conduct. As a result, each electrode 360 ​​of the multiple piezoelectric elements 60 of the print head 22 is supplied with a drive signal VOUT based on the drive signal COM output by the drive circuit 50, where the voltage value of the drive signal VOUT changes toward voltage Vb.

[0179] After the voltage value of the drive signal VOUT supplied to the electrode 360 ​​of the piezoelectric element 60 becomes constant at voltage Vb, the control circuit 100 outputs a print data signal SI that controls the logic level of the selection signal S to L level in order to control all selection circuits 230 to non-conductive. As a result, the selection circuits 230 are controlled to non-conductive. At this time, the voltage value of the electrode 360 ​​of the piezoelectric element 60 is maintained at voltage Vb by the capacitive component of the piezoelectric element 60. Subsequently, the liquid dispensing device 1 waits for a period of time until the reversal process is completed in which the scanning direction of the carriage 21 is reversed from the home position to the forward direction Fw, while the drive circuit 50 continues to output a drive signal COM with a constant voltage value of voltage Vb.

[0180] Furthermore, at a predetermined timing within the waiting period until the reversal process of the scanning direction of the carriage 21 is completed, the drive circuit 50 outputs a drive signal COM including a micro-vibration waveform obs. At this time, the control circuit 100 outputs a print data signal SI that controls the logic level of the selection signal S to an H level in order to control all selection circuits 230 to conduct. As a result, the drive signal VOUT including the micro-vibration waveform obs is supplied to the electrodes 360 of the piezoelectric element 60. Consequently, the risk of ink adhering near the nozzle 321 during the waiting period is reduced, and the risk of the ink viscosity near the nozzle 321 increasing is also reduced. Note that the drive signal VOUT including the micro-vibration waveform obs is not limited to being supplied to all piezoelectric elements 60 of the print head 22, but may be supplied to only some of the piezoelectric elements 60 of the print head 22. Also, the micro-vibration caused by the drive signal VOUT including the micro-vibration waveform obs may be performed multiple times during the waiting period.

[0181] At the time t170, once the reversal process of the scanning direction of the carriage 21 is completed, the drive circuit 50 starts outputting a signal as the drive signal COM, the voltage value of which is constant at voltage Vc. That is, it starts the same operation as at time t10 described above. In other words, the liquid dispensing device 1 of this embodiment repeatedly performs the operations from time t10 to time t160 described above, and conveys the medium P along the conveying direction, thereby forming an image on the medium P corresponding to the image information signal.

[0182] In the liquid ejection device 1 of this embodiment, which operates as described above, the temperature information output circuit 26 acquires digital temperature information dtc based on the head temperature signal TC corresponding to the temperature of the print head 22 during the period when the drive circuit 50 is outputting a drive signal COM with a constant voltage value, and the piezoelectric element 60 is not supplied with a drive signal VOUT with a fluctuating voltage value. Then, the temperature information output circuit 26 generates a temperature information signal TI corresponding to the temperature of the print head 22 based on the acquired digital temperature information dtc and outputs it to the control circuit 100. In other words, the temperature information output circuit 26 generates a temperature information signal TI corresponding to the digital temperature information dtc based on the head temperature signal TC corresponding to the temperature of the print head 22 during the period when the drive signal VOUT with a changing voltage value is not supplied to the piezoelectric element 60, and the piezoelectric element 60 is not driven by the drive signal VOUT, and therefore the diaphragm 350 is not displaced, and outputs it to the control circuit 100.

[0183] This reduces the risk of noise caused by the propagation of the drive signal VOUT, the displacement of the diaphragm 350, and instantaneous temperature changes in the ink stored in the pressure chamber 312 superimposing on the head temperature signal TC acquired by the temperature information output circuit 26. As a result, the accuracy of the head temperature signal TC acquired by the temperature information output circuit 26, specifically the detection accuracy of the temperature of the pressure chamber 312, is improved, and the reliability of the temperature information signal TI output by the temperature information output circuit 26 is enhanced.

[0184] Specifically, in the liquid dispensing device 1 of this embodiment, the temperature information output circuit 26 has the configuration shown in Figures 14 and 15. In the detection period Tdet shown in Figure 16, which is a period during which the drive signal VOUT, whose voltage value changes, is not supplied to the piezoelectric element 60, and the piezoelectric element 60 is not driven by the drive signal VOUT, and therefore the diaphragm 350 is not displaced, the temperature information output circuit 26 acquires digital temperature information dtc based on the head temperature signal TC corresponding to the temperature of the print head 22, and outputs a temperature information signal TI corresponding to the acquired digital temperature information dtc.

[0185] Figure 17 shows an example of the operation of the temperature information output circuit 26 when acquiring digital temperature information dtc during the detection period Tdet. Note that the time t80 shown in Figure 17 is the same time as the time t80 shown in Figure 16. Here, as shown in Figure 17, the voltage value of the switching voltage Vch1, which switches whether the comparison circuit 580 outputs a high-level OR signal Vcr or a low-level OR signal Vcr, is set to be between the voltage Vc, which is the voltage value at the start and end timings of the trapezoidal waveform Adp, Bdp, Cdp output as the drive signal COM during the period in which the printing process is being executed, and the voltage Vb, which is output as the drive signal COM during the detection period Tdet. The switching voltage Vch2 is set to be a voltage value smaller than the voltage Vb.

[0186] As shown in Figure 17, the half-period of the clock signal CK output by the control circuit 500, Pck, is set to be longer than the period Δt from when the voltage value of the drive signal COM starts to decrease from voltage Vc to voltage Vb at time t80. Furthermore, the half-period of the clock signal CK, Pck, is set to be longer than the time it takes for the A / D converter 530 to acquire the voltage value of the amplifier head temperature signal ATC, generate a digital signal corresponding to the acquired voltage value, and output it to the control circuit 500 as digital temperature information dtc.

[0187] As shown in Figure 17, immediately before time t80, the drive circuit 50 outputs a constant drive signal COM with a voltage Vc greater than the switching voltages Vch1 and Vch2. Therefore, immediately before time t80, the comparator circuit 580 outputs a high-level OR signal Vcr. That is, immediately before time t80, the data input terminal D1 of the D-type flip-flop 592 and the data input terminal D2 of the D-type flip-flop 594 are input with a high-level OR signal Vcr. Consequently, immediately before time t80, the D-type flip-flop 592 outputs a high-level data signal Do1, and the D-type flip-flop 594 outputs a high-level data signal Do2. Therefore, immediately before time t80, the timing control circuit 590 outputs a high-level timing control signal Tgi to the control circuit 500. In this case, the control circuit 500 does not output the enable signal EN1 that enables the operation of the A / D converter 530 because it has received a high-level timing control signal Tgi. Therefore, the A / D converter 530 does not output digital temperature information dtc corresponding to the head temperature signal TC, and the control circuit 500 does not generate a temperature information signal TI corresponding to the digital temperature information dtc.

[0188] At time t80, when the carriage 21 stops moving, the drive circuit 50 starts outputting a drive signal COM with a constant voltage value of voltage Vb. That is, the voltage value of the drive signal COM output by the drive circuit 50 decreases from voltage Vc to voltage Vb. Then, at time t81, when the voltage value of the drive signal COM output by the drive circuit 50 falls below the switching voltage Vch1, the logic level of the OR signal Vcr output by the comparator circuit 580 switches from H level to L level. That is, at time t81, an L-level OR signal Vcr is input to the data input terminal D1 of the D-type flip-flop 592 and the data input terminal D2 of the D-type flip-flop 594.

[0189] Then, after time t81, at time t82 when the clock signal CK rises, the D-type flip-flop 592 outputs an L-level data signal Do1 corresponding to the L-level OR signal Vcr input to data input terminal D1. Then, after time t81, at time t83 when the clock signal CK falls, the D-type flip-flop 594 outputs an L-level data signal Do2 corresponding to the L-level OR signal Vcr input to data input terminal D2. Therefore, at time t83, the OR circuit 596 receives both the L-level data signal Do1 and the L-level data signal Do2. As a result, the OR circuit 596 generates an L-level timing control signal Tgi, and the timing control circuit 590 outputs the L-level timing control signal Tgi to the control circuit 500.

[0190] When the control circuit 500 receives a low-level timing control signal Tgi, it outputs an enable signal EN1 to activate the A / D converter 530. When the A / D converter 530 receives the enable signal EN1, it outputs digital temperature information dtc corresponding to the head temperature signal TC, and the control circuit 500 acquires the digital temperature information dtc output by the A / D converter 530. The control circuit 500 then generates a temperature information signal TI corresponding to the acquired digital temperature information dtc. That is, the temperature information output circuit 26 acquires digital temperature information dtc based on the head temperature signal TC corresponding to the temperature of the print head 22, and outputs a temperature information signal TI corresponding to the acquired digital temperature information dtc to the control circuit 100.

[0191] At this time, the half-period of the clock signal CK output by the control circuit 500 is set to be longer than the period Δt during which the voltage value of the drive signal COM decreases from voltage Vc to voltage Vb. Therefore, at the timing t83 when the timing control circuit 590 outputs an L-level timing control signal Tgi to the control circuit 500 and the control circuit 500 acquires digital temperature information dtc, the voltage value of the drive signal COM output by the drive circuit 50 is constant at voltage Vb. Consequently, the drive signal VOUT, which has a fluctuating voltage value, is not supplied to the piezoelectric element 60. Thus, at time t83, the risk of noise caused by the propagation of the drive signal VOUT, the displacement of the diaphragm 350, and instantaneous temperature changes in the ink temperature stored in the pressure chamber 312 superimposing on the head temperature signal TC acquired by the temperature information output circuit 26 is reduced. As a result, the accuracy of the head temperature signal TC acquired by the temperature information output circuit 26 is improved, and the accuracy of detecting the temperature of the pressure chamber 312 is enhanced, improving the reliability of the temperature information signal TI output by the temperature information output circuit 26.

[0192] As described above, in the liquid dispensing device 1 of this embodiment, the timing control circuit 590 of the temperature information output circuit 26 determines whether the voltage value of the drive signal COM is within a predetermined range for a predetermined time or longer, and controls the timing at which the control circuit 500 acquires the digital temperature information dtc based on the determination result. Specifically, the timing control circuit 590 of this embodiment determines that the voltage value of the drive signal COM is constant when the voltage value of the drive signal COM is below the switching voltage Vch1 and above the switching voltage Vch2 for a predetermined time or longer, and outputs an L-level timing control signal Tgi, thereby controlling the control circuit 500 to acquire the digital temperature information dtc. Here, the time of half a cycle of the period Pck of the clock signal CK corresponds to the predetermined time in this embodiment. As a result, the temperature information output circuit 26 does not have a complex configuration, and the risk of noise caused by the propagation of the drive signal VOUT, the displacement of the diaphragm 350, and instantaneous temperature changes of the ink stored in the pressure chamber 312 being superimposed on the head temperature signal TC acquired by the temperature information output circuit 26 is reduced. As a result, the accuracy of the head temperature signal TC acquired by the temperature information output circuit 26 is improved, and the accuracy of detecting the temperature of the pressure chamber 312 is enhanced, improving the reliability of the temperature information signal TI output by the temperature information output circuit 26.

[0193] In Figure 17, the explanation assumes that the clock signal CK rises at time t82 and falls at time t83. However, the clock signal CK may fall at time t82 and rise at time t83. In that case, at time t82 when the clock signal CK falls, the D-type flip-flop 594 outputs an L-level data signal Do2 corresponding to the L-level OR signal Vcr input to data input terminal D2. Also, at time t83 when the clock signal CK rises, the D-type flip-flop 592 outputs an L-level data signal Do1 corresponding to the L-level OR signal Vcr input to data input terminal D1. Subsequently, the operation shown in Figure 17 is executed.

[0194] The drive signal COM, which consists of consecutive trapezoidal waveforms Adp, Bdp, and Cdp, is a waveform whose voltage value fluctuates over time. In Figure 17, as in the case when the drive signal COM transitions from voltage Vc to voltage Vb, the voltage value of the drive signal COM may fall below a predetermined voltage value, i.e., below the switching voltage Vch1 and above the switching voltage Vch2, even as the voltage value transitions. In other words, determining that the voltage value has become constant simply because it has reached a predetermined voltage value may lead to misjudgment, potentially reducing the accuracy of acquiring digital temperature information dtc based on the head temperature signal TC in the temperature information output circuit 26.

[0195] To address this problem, in the liquid dispensing device 1 of this embodiment, by optimally setting the period of the clock signal CK that acquires the logical OR signal Vcr in the D-type flip-flops 592 and 594, the risk of the temperature information output circuit 26 mistakenly determining that the voltage value of the drive signal COM is constant when the voltage value of the drive signal COM reaches a predetermined voltage value is reduced. As a result, the risk of a decrease in the acquisition accuracy of the digital temperature information dtc based on the head temperature signal TC in the temperature information output circuit 26 is reduced.

[0196] Next, we will explain the period of the clock signal CK. Figure 18 shows an example of the waveform of the drive signal COM during a period when the drive circuit 50 outputs a drive signal COM consisting of consecutive trapezoidal waveforms Adp, Bdp, and Cdp, for example, during a part of the period from time t30 to time t60 as shown in Figure 16.

[0197] Figure 18 shows periods Ph1, Ph2, and Ph3 where the voltage value of the drive signal COM, which consists of consecutive trapezoidal waveforms Adp, Bdp, and Cdp, is equal to or greater than the switching voltage Vch1, and periods Pq1 and Pq2 where the voltage value of the drive signal COM, which consists of consecutive trapezoidal waveforms Adp, Bdp, and Cdp, is less than the switching voltage Vch1 and equal to or greater than the switching voltage Vch2. Here, period Ph1 shown in Figure 18 is continuous with period Ph3 in the immediately preceding period tp. Therefore, periods Ph1 and Ph3 can be considered as one continuous period. In the following explanation, the period in which periods Ph1 and Ph3 are continuous will be referred to as period Ph4.

[0198] Figures 19, 20, and 21 show an example of the relationship between the drive signal COM and the clock signal during period Pq1. In Figures 19, 20, and 21, period TL1 is defined as the period during which the drive signal COM falls below the switching voltage Vch1 and transitions to a constant voltage, and period TL2 is defined as the period during which the constant voltage is maintained.

[0199] In Figure 19, during period TL2, the clock signal CK rises and then falls. That is, the rising and falling edges of this clock signal CK cause the D-type flip-flop 594 to output an L-level data signal Do2 corresponding to the L-level OR signal Vcr input to data input terminal D2, and the D-type flip-flop 592 outputs an L-level data signal Do1 corresponding to the L-level OR signal Vcr input to data input terminal D1. Therefore, the timing control circuit 590 detects the period TL2 in which the voltage value is constant, determines that the voltage value of the drive signal COM has remained constant for a predetermined time or longer, and outputs an L-level timing control signal Tgi, thereby controlling the control circuit 500 to acquire digital temperature information dtc.

[0200] In Figure 20, the clock signal CK rises during period TL1, and falls during period TL2. That is, the rising and falling edges of the clock signal CK cause the D-type flip-flop 594 to output an L-level data signal Do2 corresponding to the L-level OR signal Vcr input to data input terminal D2, and the D-type flip-flop 592 to output an L-level data signal Do1 corresponding to the L-level OR signal Vcr input to data input terminal D1. However, because the clock signal CK rises during period TL1, there is a risk of misjudging the drive signal COM as constant during periods when the drive signal COM is not constant. In other words, there is a risk that noise caused by the propagation of the drive signal VOUT may be superimposed on the head temperature signal TC acquired by the temperature information output circuit 26.

[0201] In Figure 21, during period TL2, the clock signal CK rises, then falls after exceeding period Pq1. Specifically, the rising edge of the clock signal CK causes the D-type flip-flop 592 to output an L-level data signal Do1 corresponding to the L-level OR signal Vcr input to data input terminal D1, and the falling edge of the clock signal CK causes the D-type flip-flop 594 to output an H-level data signal Do2 corresponding to the H-level OR signal Vcr input to data input terminal D2. Consequently, the timing control circuit 590 cannot detect the period TL2 in which the voltage value is constant, and therefore does not control the control circuit 500 to acquire the digital temperature information dtc by outputting an H-level timing control signal Tgi.

[0202] As shown in the examples in Figures 19, 20, and 21, the length of the half-period of the clock signal CK must be defined in order to accurately detect and determine the period during which the voltage value of the drive signal COM is constant. As shown in the examples in Figures 19 and 21, the length of the half-period of the clock signal CK must be shorter than the period during which the voltage of the drive signal COM is constant within one cycle of the drive signal COM. Furthermore, as shown in the example in Figure 20, the length of the half-period of the clock signal CK must be longer than the period during which the drive signal COM transitions from a first voltage to a second voltage and maintains the second voltage for a certain period within one cycle of the drive signal COM.

[0203] Furthermore, the half-period length of the clock signal CK must be set to be longer than the time it takes for the A / D converter 530 to acquire the voltage value of the amplification head temperature signal ATC, generate a digital signal corresponding to the acquired voltage value, and output it to the control circuit 500 as digital temperature information dtc. Also, the half-period length of the clock signal CK must be set to be longer than the time it takes for the A / D converter 560 to acquire the voltage value of the amplification unit temperature signal ATH, generate a digital signal corresponding to the acquired voltage value, and output it to the control circuit 500 as digital temperature information dth. This is to prevent the clock signal CK from rising or falling before the digital temperature information dtc and dth are output, thus preventing the temperature information output circuit 26 from moving on to the next operation.

[0204] As described above, by defining the length of half a cycle of the clock signal CK, the timing control circuit 590 accurately detects the period during which the drive signal COM maintains a constant voltage value without misdetection. This reduces the risk of noise caused by the propagation of the drive signal COM, the displacement of the diaphragm 350, and instantaneous temperature changes in the ink stored in the pressure chamber 312 superimposing on the head temperature signal TC acquired by the temperature information output circuit 26. As a result, the accuracy of the head temperature signal TC acquired by the temperature information output circuit 26 is improved, and the accuracy of detecting the temperature of the pressure chamber 312 is improved, thereby improving the reliability of the temperature information signal TI output by the temperature information output circuit 26.

[0205] Here, control circuit 500 is an example of a temperature information acquisition circuit, and the digital temperature information dtc acquired by control circuit 500 is an example of temperature information. Also, D-type flip-flop 592 is an example of a first D-type flip-flop circuit, and the data signal Do1 output by D-type flip-flop 592 is an example of a first data signal. D-type flip-flop 594 is an example of a second D-type flip-flop circuit, and the data signal Do2 output by D-type flip-flop 594 is an example of a second data signal. Also, OR circuit 596 is an example of a second logic element. Also, in comparison circuit 580, comparator 582 is an example of a first comparator, and comparator 581 is an example of a second comparator. Also, OR circuit 583 is an example of a first logic element. Also, among the logic levels, L level is an example of a first logic level, and H level is an example of a second logic level. Furthermore, the voltage value of the switching voltage Vch1 is an example of the first threshold, and the voltage value of the switching voltage Vch2 is an example of the second threshold. Also, the clock signal CK is an example of the clock signal. And electrode 360 ​​is an example of the first electrode, electrode 380 is an example of the second electrode, the direction along the Z axis of the print head 22 is an example of the stacking direction, the +Z side of the print head 22 is an example of one side, the -Z side of the print head 22 is an example of the other side, and the resistor wiring 401 is an example of the temperature detection unit.

[0206] 1-8. Effects In the liquid ejection device 1 and head unit 20 of this embodiment configured as described above, the temperature information output circuit 26 that acquires a head temperature signal TC corresponding to the temperature of the print head 22 includes a control circuit 500 that acquires digital temperature information dtc corresponding to the temperature of the print head 22 from the head temperature signal TC, and a timing control circuit 590 that controls the timing at which the control circuit 500 acquires the digital temperature information dtc. The timing control circuit 590 outputs a timing control signal Tgi that controls the control circuit 500 to acquire the digital temperature information dtc when the voltage value of the drive signal COM is within a predetermined range for a predetermined time or longer. This reduces the risk of noise caused by the propagation of the drive signal VOUT, the displacement of the diaphragm 350, and instantaneous temperature changes in the ink stored in the pressure chamber 312 superimposing on the head temperature signal TC acquired by the control circuit 500. As a result, the accuracy of the head temperature signal TC acquired by the temperature information output circuit 26 is improved, and the accuracy of detecting the temperature of the pressure chamber 312 is improved, and the reliability of the temperature information signal TI output by the temperature information output circuit 26 is improved. In other words, the accuracy of temperature detection for the print head 22 is improved.

[0207] Furthermore, in the liquid ejection device 1 and head unit 20 of this embodiment, the print head 22 of the head unit 20 includes an electrode 360, an electrode 380, and a piezoelectric element 370, and in the direction along the Z-axis in which the electrodes 360, 380, and 370 are stacked, the piezoelectric element 60 is located between the electrodes 360 and 380 and is driven by a drive signal COM, a diaphragm 350 is located on the +Z side, which is one side along the Z-axis with respect to the piezoelectric element 60, and is deformed by the driving of the piezoelectric element 60, and a pressure chamber 312 is located on the +Z side, which is one side along the Z-axis with respect to the diaphragm 350, and is provided in which ink is stored and the volume changes due to the deformation of the diaphragm 350. Even if the head temperature signal TC acquired by the control circuit 500 includes a pressure chamber substrate 310, a nozzle 321 that ejects ink in accordance with changes in the volume of the pressure chamber 312, and a resistor wiring 401 located on the -Z side, which is the other side of the Z-axis relative to the diaphragm 350, and which acquires a temperature corresponding to the temperature of the pressure chamber 312, the timing control circuit 590 determines whether the voltage value of the drive signal COM is constant, and controls the timing of acquisition of digital temperature information dtc in the control circuit 500 based on the determination result. This reduces the risk of noise caused by the propagation of the drive signal VOUT, the displacement of the diaphragm 350, and instantaneous temperature changes in the ink stored in the pressure chamber 312 being superimposed on the head temperature signal TC acquired by the control circuit 500. Therefore, the accuracy of temperature detection of the print head 22 is further improved.

[0208] Furthermore, in the liquid ejection device 1 and head unit 20 of this embodiment, the accuracy of detecting the temperature of the print head 22 is improved. Therefore, by correcting the drive signal COM output by the drive circuit 50 based on the temperature of the print head 22, the accuracy of ink ejection from the print head 22 can be improved.

[0209] 2. Second Embodiment In the first embodiment, a configuration was described in which it is determined whether the voltage of only one drive signal COM is constant. In the second embodiment, an example is described in which it is determined whether multiple drive signals COMA and COMB are constant. In the liquid ejection device 1 of the first embodiment, the piezoelectric element 370 deforms based on the drive signal COM and ejects ink. On the other hand, in the liquid ejection device 1 of the second embodiment, by applying multiple drive signals COMA and COMB to the piezoelectric element 370, it becomes possible to eject ink droplets of different sizes, and a higher-resolution image can be formed.

[0210] The explanation will be omitted for those components that have the same configuration as the liquid dispensing device 1 of the first embodiment. Figure 22 is a diagram showing the functional configuration of the liquid dispensing device 1 of the second embodiment. As shown in Figure 22, the control circuit 100 of the liquid dispensing device 1 in the second embodiment generates digital base drive signals dAA and dAB and outputs them to drive circuits 50A and 50B, respectively. Drive circuit 50A generates a drive signal COMA, which has a signal waveform defined by the base drive signal dAA, and outputs it to the head unit 20. Drive circuit 50B generates a drive signal COMB, which has a signal waveform defined by the base drive signal dAB, and outputs it to the head unit 20.

[0211] Specifically, the base drive signal dAA output by the control circuit 100 is input to the drive circuit 50A, and the base drive signal dAB is input to the drive circuit 50B. The drive circuit 50A converts the input base drive signal dAA from digital to analog, then generates a drive signal COMA by class D amplification of the converted analog signal and outputs it to the head unit 20. The drive circuit 50B converts the input base drive signal dAB from digital to analog, then generates a drive signal COMB by class D amplification of the converted analog signal and outputs it to the head unit 20. In other words, the control circuit 100 outputs base drive signals dAA and dAB corrected based on the temperature information signal TI, and the drive circuits 50A and 50B output drive signals COMA and COMB with signal waveforms corrected according to the base drive signals dAA and dAB corrected based on the temperature information signal TI. Here, we will explain that the base drive signals dAA and dAB output by the control circuit 100 are digital signals that define the signal waveforms of the drive signals COMA and COMB. However, the base drive signals dAA and dAB only need to define the signal waveforms of the drive signals COMA and COMB, and may be analog signals. Furthermore, the drive circuits 50A and 50B may generate the drive signals COMA and COMB by performing Class A amplification, Class B amplification, and Class AB amplification on the signal waveforms defined by the base drive signals dAA and dAB.

[0212] As described above, the drive circuits 50A and 50B generate and output drive signals COMA and COMB based on the base drive signals dAA and dAB. At this time, the base drive signals dAA and dAB input to the drive circuits 50A and 50B, and the base drive signals dAA and dAB output by the control circuit 100, are also corrected based on the temperature of the head unit 20, which is determined based on the temperature information signal TI. Therefore, the drive circuits 50A and 50B output drive signals COMA and COMB that have been corrected based on the temperature of the head unit 20. The drive signals COMA and COMB are then input to the temperature information output circuit 26 provided in the head unit 20 and to the respective drive signal selection circuits 200 of the print heads 22-1 to 22-n, which are multiple print heads 22 provided in the head unit 20.

[0213] Next, the configuration and operation of the temperature information output circuit 26 will be described. Figure 23 shows an example of the configuration of the temperature information output circuit 26. In this embodiment, the drive signal COMA and the drive signal COMB are input to the comparison circuit 580. The comparison circuit 580 compares the voltage values ​​of the input drive signals COMA and COMB with predetermined voltage values ​​and outputs a logical OR signal Vcr whose logic level changes according to the comparison result.

[0214] Next, the details of the comparison circuit 580 and the timing control circuit 590 will be described. Figure 24 is a diagram showing an example of the configuration of the comparison circuit 580 and the timing control circuit 590 in the second embodiment. The comparator circuit 580 includes comparators 581A, 582A, 581B, 582B, resistors 584A, 586A, 584B, 586B, and an OR circuit 583. One end of resistor 584A is input to the drive signal COMA. The other end of resistor 584A is electrically connected to one end of resistor 586A. The other end of resistor 586A is supplied with ground potential. The connection point between the other end of resistor 584A and one end of resistor 586A is electrically connected to the + input terminal of comparator 581A and the - input terminal of comparator 582A.

[0215] Furthermore, the threshold voltage signal VthA_Hi is input to the negative input terminal of comparator 581A. Comparator 581A generates a comparison result signal Co1A, which is high level when the voltage value at the positive input terminal is greater than or equal to the voltage value at the negative input terminal, and low level when the voltage value at the positive input terminal is less than the voltage value at the negative input terminal, and outputs this signal from its output terminal. Similarly, the threshold voltage signal VthA_Low is input to the positive input terminal of comparator 582A. Comparator 582A generates a comparison result signal Co2A, which is high level when the voltage value at the positive input terminal is greater than or equal to the voltage value at the negative input terminal, and low level when the voltage value at the positive input terminal is less than the voltage value at the negative input terminal, and outputs this signal from its output terminal. Although not shown in the figure, the threshold voltage signals VthA_Hi and VthA_Low are generated, for example, by a threshold voltage signal generator in the liquid discharge device 1 and supplied to comparators 581A and 582A.

[0216] Furthermore, the drive signal COMB is input to one end of resistor 584B. The other end of resistor 584B is electrically connected to one end of resistor 586B. Ground potential is supplied to the other end of resistor 586B. The connection point between the other end of resistor 584B and one end of resistor 586B is electrically connected to the + side input terminal of comparator 581B and the - side input terminal of comparator 582B.

[0217] Furthermore, the threshold voltage signal VthB_Hi is input to the negative input terminal of comparator 581B. Comparator 581B then generates a comparison result signal Co1B, which is high level when the voltage value at the positive input terminal is greater than or equal to the voltage value at the negative input terminal, and low level when the voltage value at the positive input terminal is less than the voltage value at the negative input terminal, and outputs this signal from its output terminal. Similarly, the threshold voltage signal VthB_Low is input to the positive input terminal of comparator 582B. Comparator 582B then generates a comparison result signal Co2B, which is high level when the voltage value at the positive input terminal is greater than or equal to the voltage value at the negative input terminal, and low level when the voltage value at the positive input terminal is less than the voltage value at the negative input terminal, and outputs this signal from its output terminal. Although not shown in the figure, the threshold voltage signals VthB_Hi and VthB_Low are generated, for example, by a threshold voltage signal generator in the liquid discharge device 1 and supplied to comparators 581B and 582B.

[0218] The OR circuit 583 is electrically connected to comparators 581A, 582A, 581B, and 582B, and receives the comparison result signals Co1A, Co2A, Co1B, and Co2B as input. It outputs a logical OR signal Vcr according to the logic level of each of the comparison result signals Co1A, Co2A, Co1B, and Co2B. Specifically, if all of the comparison result signals Co1A, Co2A, Co1B, and Co2B are at the L level, it outputs a logical OR signal Vcr at the L level. If any one of the comparison result signals Co1A, Co2A, Co1B, and Co2B is at the H level, it outputs a logical OR signal Vcr at the H level.

[0219] Hereinafter, in the following explanation, the predetermined voltage values ​​of the drive signal COMA that switches the logic level of the OR signal Vcr output by the comparator circuit 580, which are the predetermined voltage values ​​mentioned above, will be referred to as switching voltages Vch1A and Vch2A. Similarly, the predetermined voltage values ​​of the drive signal COMB that switches the logic level of the OR signal Vcr output by the comparator circuit 580, which are referred to as switching voltages Vch1B and Vch2B. Switching voltage Vch1A is assumed to be a voltage value greater than switching voltage Vch2A, and switching voltage Vch1B is assumed to be a voltage value greater than Vch2B.

[0220] In other words, the comparator circuit 580 compares the voltage value of the drive signal COMA with the switching voltages Vch1A and Vch2A. If the voltage value of the drive signal COMA is less than the switching voltage Vch1A and greater than or equal to the voltage value of the switching voltage Vch2A, AND the voltage value of the drive signal COMB is compared with the switching voltages Vch1B and Vch2B, and the voltage value of the drive signal COMB is less than the switching voltage Vch1B and greater than or equal to the voltage value of the switching voltage Vch2B, it outputs a logical OR signal Vcr at a low level. In other cases, for example, if the voltage value of the drive signal COMA is greater than or equal to the voltage value of the switching voltage Vch1A, or if the voltage value of the drive signal COMB is greater than or equal to the voltage value of the switching voltage Vch1B, it outputs a logical OR signal Vcr at a high level. Also, if the voltage value of the drive signal COMA is less than the voltage value of the switching voltage Vch2A, or if the voltage value of the drive signal COMB is less than the voltage value of the switching voltage Vch2B, it outputs a logical OR signal Vcr at a high level.

[0221] The timing control circuit 590 includes D-type flip-flops 592 and 594 and an OR circuit 596, and operates in the same manner as in the first embodiment, so a detailed explanation is omitted.

[0222] Figure 25 shows an example of the waveforms of drive signals COMA and COMB. Drive signal COMA starts at voltage Vc_A and ends at voltage Vc_A in period tp. Drive signal COMB starts at voltage Vc_B and ends at voltage Vc_B in period tp. Furthermore, the period in which the voltage value of drive signal COMA is less than the switching voltage Vch1A and greater than or equal to the switching voltage Vch2A, and the voltage value of drive signal COMB is less than the switching voltage Vch1B and greater than or equal to the switching voltage Vch2B, is defined as period Pu.

[0223] Figure 26 shows an example of the operation of the temperature information output circuit 26 when acquiring digital temperature information dtc during period Pu. As shown in Figure 26, immediately before period Pu, the drive signal COMA output by the drive circuit 50A has a voltage value greater than the switching voltage Vch1A. Therefore, immediately before period Pu, the comparator circuit 580 outputs a high-level OR signal Vcr. That is, immediately before period Pu, the data input terminal D1 of the D-type flip-flop 592 and the data input terminal D2 of the D-type flip-flop 594 are input with a high-level OR signal Vcr. Consequently, immediately before period Pu, the D-type flip-flop 592 outputs a high-level data signal Do1, and the D-type flip-flop 594 outputs a high-level data signal Do2. Therefore, immediately before period Pu, the timing control circuit 590 outputs a high-level timing control signal Tgi to the control circuit 500. In this case, the control circuit 500 does not output the enable signal EN1 that enables the operation of the A / D converter 530 because it has received a high-level timing control signal Tgi. Therefore, the A / D converter 530 does not output digital temperature information dtc corresponding to the head temperature signal TC, and the control circuit 500 does not generate a temperature information signal TI corresponding to the digital temperature information dtc.

[0224] Subsequently, during period Pu, the voltage value of the drive signal COMA becomes less than the switching voltage Vch1A and greater than or equal to the switching voltage Vch2A, and the voltage value of the drive signal COMB becomes less than the switching voltage Vch1B and greater than or equal to the switching voltage Vch2B. Then, the logic level of the OR signal Vcr output by the comparator circuit 580 switches from H level to L level. That is, at the timing of entering period Pu, an L-level OR signal Vcr is input to the data input terminal D1 of the D-type flip-flop 592 and the data input terminal D2 of the D-type flip-flop 594.

[0225] Then, during period Pu, at the time when the clock signal CK first rises, the D-type flip-flop 592 outputs an L-level data signal Do1 corresponding to the L-level OR signal Vcr input to data input terminal D1. Subsequently, at the time when the clock signal CK falls, the D-type flip-flop 594 outputs an L-level data signal Do2 corresponding to the L-level OR signal Vcr input to data input terminal D2. Therefore, the OR circuit 596 receives both the L-level data signal Do1 and the L-level data signal Do2. As a result, the OR circuit 596 generates an L-level timing control signal Tgi, and the timing control circuit 590 outputs the L-level timing control signal Tgi to the control circuit 500.

[0226] When the control circuit 500 receives a low-level timing control signal Tgi, it outputs an enable signal EN1 to activate the A / D converter 530. When the A / D converter 530 receives the enable signal EN1, it outputs digital temperature information dtc corresponding to the head temperature signal TC, and the control circuit 500 acquires the digital temperature information dtc output by the A / D converter 530. The control circuit 500 then generates a temperature information signal TI corresponding to the acquired digital temperature information dtc. That is, the temperature information output circuit 26 acquires digital temperature information dtc based on the head temperature signal TC corresponding to the temperature of the print head 22, and outputs a temperature information signal TI corresponding to the acquired digital temperature information dtc to the control circuit 100.

[0227] At this time, when the voltage values ​​of the drive signals COMA and COMB output by the drive circuits 50A and 50B during period Pu are constant, the A / D converter 530 receives an enable signal EN1 to activate its operation. Therefore, at that timing, the piezoelectric element 60 is not supplied with a drive signal VOUT whose voltage value fluctuates. Thus, the risk of noise caused by the propagation of the drive signal VOUT, the displacement of the diaphragm 350, and instantaneous temperature changes in the ink stored in the pressure chamber 312 being superimposed on the head temperature signal TC acquired by the temperature information output circuit 26 is reduced.

[0228] As described above, even when multiple drive signals COMA and COMB are supplied to the piezoelectric element 60, the timing control circuit 590 of the temperature information output circuit 26 outputs a timing control signal Tgi that controls the control circuit 500 to acquire digital temperature information dtc when the voltage values ​​of the drive signals COMA and COMB are within a predetermined range for a predetermined time or longer. This reduces the risk of noise caused by the propagation of the drive signal VOUT, the displacement of the diaphragm 350, and instantaneous temperature changes of the ink stored in the pressure chamber 312 superimposing on the head temperature signal TC acquired by the temperature information output circuit 26, without requiring the temperature information output circuit 26 to have a complex configuration. As a result, the accuracy of the head temperature signal TC acquired by the temperature information output circuit 26 is improved, and the accuracy of detecting the temperature of the pressure chamber 312 is improved, and the reliability of the temperature information signal TI output by the temperature information output circuit 26 is improved.

[0229] 3. Variant In the liquid dispensing device 1 of the first embodiment described above, the comparison circuit 580 compares the voltage value of the drive signal COM with the switching voltages Vch1 and Vch2. Specifically, the comparison circuit 580 compares the voltage value of the drive signal COM with the switching voltages Vch1 and Vch2, and outputs a logical OR signal Vcr at an H level if the voltage value of the drive signal COM is greater than or equal to the voltage values ​​of the switching voltages Vch1 and Vch2. Furthermore, if the voltage value of the drive signal COM is less than the voltage value of the switching voltage Vch1 and greater than or equal to the voltage value of Vch2, it outputs a logical OR signal Vcr at an L level. In addition, if the voltage value of the drive signal COM is less than the voltage values ​​of the switching voltages Vch1 and Vch2, it outputs a logical OR signal Vcr at an H level. As explained above, the comparison circuit 580 compares the voltage value of the drive signal COM with the switching voltages Vch1 and Vch2. If the voltage value of the drive signal COM is greater than or equal to the voltage values ​​of the switching voltages Vch1 and Vch2, it outputs a logical OR signal Vcr at an L level. If the voltage value of the drive signal COM is less than the switching voltage Vch1 and greater than or equal to the voltage value of the switching voltage Vch2, it outputs a logical OR signal Vcr at an H level. Furthermore, if the voltage value of the drive signal COM is less than the voltage values ​​of the switching voltages Vch1 and Vch2, it may output a logical OR signal Vcr at an L level. In this case, the timing control circuit 590 has an AND circuit instead of the OR circuit 596, and the control circuit 500 outputs an enable signal EN1 to activate the A / D converter 530 when the input timing control signal Tgi changes from an L level to an H level, thereby achieving the same effects as in the embodiment described above. In this case, the AND circuit provided in place of the OR circuit 596 corresponds to another example of a logic element.

[0230] Furthermore, in the liquid ejection device 1 described above, the example given was that the resistor wiring 401, which constitutes part of the temperature detection circuit 250, is formed on the diaphragm 350. However, the temperature detection circuit 250 is not limited to this configuration; it only needs to be able to detect the temperature of the print head 22 and the temperature of the ink stored in the print head 22.

[0231] Although embodiments and modified examples have been described above, the present invention is not limited to these embodiments and can be implemented in various forms without departing from its spirit. For example, the above embodiments can be combined as appropriate.

[0232] The present invention includes configurations that are substantially identical to those described in the embodiments (for example, configurations with the same function, method, and result, or configurations with the same purpose and effect). Furthermore, the present invention includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. Furthermore, the present invention includes configurations that produce the same effects or achieve the same purpose as those described in the embodiments. Furthermore, the present invention includes configurations that add known technology to the configurations described in the embodiments. [Explanation of symbols]

[0233] 1…Liquid dispensing device, 10…Control unit, 20…Head unit, 21…Carriage, 22…Print head, 26…Temperature information output circuit, 28…Temperature detection circuit, 30…Movement unit, 31…Carriage motor, 32…Endless belt, 40…Conveyor unit, 41…Conveyor motor, 42…Conveyor roller, 50…Drive circuit, 52…Reference voltage output circuit, 60…Piezoelectric element, 90…Ink container, 92…Encoder sensor, 94…Notification circuit, 100…Control circuit, 200…Drive signal selection circuit, 210…Selection control circuit, 212…Shift register, 214…Latch circuit, 216…Decoder, 230…Selection circuit, 232…Inverter, 234…Transfer gate, 250…Temperature detection circuit, 252,254…Resistors, 310…Pressure chamber substrate, 311…Partition wall, 312…Pressure chamber, 312a,312b…End section, 315…Communication plate, 316…Nozzle communication passage, 317…First manifold section, 318…Second manifold section, 319…Supply communication passage, 320…Nozzle plate, 321…Nozzle, 330…Protective substrate, 331…Holding section, 332…Through hole, 340…Case member, 341…Housing section, 342… Third manifold section, 343...connection port, 344...supply port, 345...compliance substrate, 346...sealing film, 347...fixing substrate, 348...opening, 349...compliance section, 350...diaphragm, 351...elastic film, 352...insulating film, 360, 380...electrodes, 360a, 360b...ends, 370...piezoelectric material, 370a, 370b...ends, 371...groove section, 380a, 380b...ends, 385...wiring section, 391...individual lead electrodes, 392...common lead electrodes, 392a, 392b...extension section, 393, 393a, 393b...measuring lead electrodes, 400...Manifold, 401...Resistor wiring, 410...Active part, 415...Inactive part, 420...Wiring board, 421...Integrated circuit, 500...Control circuit, 501...Requirement analysis part, 502...Clock signal output part, 503...Temperature information output part, 504...Correction value calculation part, 505...Memory control part, 510...Multiplexer, 520,550...Amplification circuit, 530,560...A / D converter, 570...Memory circuit, 580...Comparator circuit, 581,582...Comparator, 583...OR circuit, 584,586...Resistor, 590...Timing control circuit, 592,594…D-type flip-flop, 596…OR circuit, ATC…Amplifier head temperature signal, ATH…Amplifier unit temperature signal, Adp, Bdp, Cdp…Trapezoidal waveform, CH…Change signal, CK…Clock signal, CLK1, CLK2…Clock input terminals, COM…Drive signal, Co1, Co2…Comparison result signals, Ctrl-C, Ctrl-H, Ctrl-M, Ctrl-T…Control signals, D1, D2…Data input terminals, Do1, Do2…Data signals, EN1, EN2…Enable signals, LAT…Latch signal, MA…Memory control signal, MR…Memory read signal, P…Media, PS…Position detection signals, Q1, Q 2…Data output terminal, S…Selection signal, SCK…Clock signal, SI…Print data signal, STC…Selection temperature signal, Sel…Selection signal, TC…Head temperature signal, TD…Temperature acquisition request signal, TH…Unit temperature signal, TI…Temperature information signal, TL1,TL2…Period, Tdet…Detection period, Tgi…Timing control signal, VBS…Reference voltage signal, VDD…Voltage signal, VOUT…Drive signal, Vb,Vc…Voltage, Vch1,Vch2…Switching voltage, Vcr…Logical OR signal, Vth_Hi,Vth_Low…Threshold voltage signal, dA…Base drive signal, dtc,dth…Digital temperature information, obs…Micro-vibration waveform.

Claims

1. A drive circuit that outputs a drive signal, A print head that receives the aforementioned drive signal and ejects liquid, A temperature information output circuit that acquires a head temperature signal corresponding to the temperature of the print head, Equipped with, The aforementioned temperature information output circuit is A temperature information acquisition circuit that acquires temperature information corresponding to the temperature of the print head from the head temperature signal, The temperature information acquisition circuit includes a timing control circuit that controls the timing for acquiring the temperature information, It has, The timing control circuit outputs a timing control signal that controls the temperature information acquisition circuit to acquire the temperature information when the voltage value of the drive signal is within a predetermined range for a predetermined time or longer. A liquid dispensing device characterized by the following features.

2. The temperature information output circuit includes a comparison circuit. The comparison circuit comprises a first comparator, a second comparator, and a first logic element. The first comparator compares the voltage value of the drive signal with a first threshold, outputs a first logic level if the voltage value of the drive signal is greater than or equal to the first threshold, and outputs a second logic level if the voltage value of the drive signal is less than the first threshold. The second comparator compares the voltage value of the drive signal with a second threshold, outputs the first logic level if the voltage value of the drive signal is less than the second threshold, and outputs the second logic level if the voltage value of the drive signal is greater than or equal to the second threshold. The outputs of the first comparator and the second comparator are input to the first logic element, and when both the outputs of the first comparator and the second comparator are at the first logic level, the first logic element outputs the first logic level. The aforementioned timing control circuit is The output of the first logic element and the clock signal are input to a first type D flip-flop circuit and a second type D flip-flop circuit, The device comprises a first data signal output by the first type D flip-flop circuit and a second logic element to which the second data signal output by the second type D flip-flop circuit is input, The first type D flip-flop circuit outputs the first data signal at the first logic level if the output of the first logic element at the rising edge of the clock signal is at the first logic level. The second type D flip-flop circuit outputs the second data signal at the first logic level if the output of the first logic element at the falling edge of the clock signal is at the first logic level. The second logic element outputs the logic level of the first data signal and the timing control signal corresponding to the logic level of the second data signal. The liquid dispensing device according to feature 1.

3. The length of half a cycle of the clock signal is shorter than the period during which the voltage of the drive signal remains constant. The liquid dispensing device according to feature 2.

4. The length of half a cycle of the clock signal is longer than the time required for the temperature information acquisition circuit to acquire the temperature information, and within the period of one cycle of the drive signal, when the drive signal transitions from the first voltage to the second voltage and maintains the second voltage for a certain period of time, the length of half a cycle of the clock signal is longer than the period of transition from the first voltage to the second voltage. The liquid dispensing device according to feature 2.

5. The first comparator and the second comparator are composed of operational amplifiers or comparators. The liquid dispensing device according to feature 2.

6. The aforementioned print head is A piezoelectric element comprising a first electrode, a second electrode, and a piezoelectric body, wherein in the stacking direction in which the first electrode, the second electrode, and the piezoelectric body are stacked, the piezoelectric body is positioned between the first electrode and the second electrode, and the piezoelectric element is driven by receiving the drive signal, A diaphragm is located on one side of the stacking direction relative to the piezoelectric element and deforms when the piezoelectric element is driven, A pressure chamber substrate is provided, located on one side of the diaphragm in the stacking direction, in which a liquid is stored and a pressure chamber whose volume changes due to the deformation of the diaphragm. A nozzle that discharges liquid in accordance with the change in volume of the pressure chamber, A temperature detection unit located on the other side of the stacking direction relative to the diaphragm, which outputs the head temperature signal corresponding to the temperature of the pressure chamber, Having, A liquid dispensing device according to any one of claims 1 to 5.

7. A print head that receives a drive signal and ejects liquid, A temperature information output circuit that acquires a head temperature signal corresponding to the temperature of the print head, Equipped with, The aforementioned temperature information output circuit is A temperature information acquisition circuit that acquires temperature information corresponding to the temperature of the print head from the head temperature signal, The temperature information acquisition circuit includes a timing control circuit that controls the timing for acquiring the temperature information, It has, The timing control circuit outputs a timing control signal that controls the temperature information acquisition circuit to acquire the temperature information when the voltage value of the drive signal is within a predetermined range for a predetermined time or longer. A head unit characterized by the following features.

8. The temperature information output circuit includes a comparison circuit. The comparison circuit comprises a first comparator, a second comparator, and a first logic element. The first comparator compares the voltage value of the drive signal with a first threshold, outputs a first logic level if the voltage value of the drive signal is greater than or equal to the first threshold, and outputs a second logic level if the voltage value of the drive signal is less than the first threshold. The second comparator compares the voltage value of the drive signal with a second threshold, outputs the first logic level if the voltage value of the drive signal is less than the second threshold, and outputs the second logic level if the voltage value of the drive signal is greater than or equal to the second threshold. The outputs of the first comparator and the second comparator are input to the first logic element, and when both the outputs of the first comparator and the second comparator are at the first logic level, the first logic element outputs the first logic level. The aforementioned timing control circuit is The output of the first logic element and the clock signal are input to a first type D flip-flop circuit and a second type D flip-flop circuit, The device comprises a first data signal output by the first type D flip-flop circuit and a second logic element to which the second data signal output by the second type D flip-flop circuit is input, The first type D flip-flop circuit outputs the first data signal at the first logic level if the output of the first logic element at the rising edge of the clock signal is at the first logic level. The second type D flip-flop circuit outputs the second data signal at the first logic level if the output of the first logic element at the falling edge of the clock signal is at the first logic level. The second logic element outputs the logic level of the first data signal and the timing control signal corresponding to the logic level of the second data signal. The head unit according to feature 7.

9. The length of half a cycle of the clock signal is shorter than the period during which the voltage of the drive signal remains constant. The head unit according to feature 8.

10. The length of half a cycle of the clock signal is longer than the time required for the temperature information acquisition circuit to acquire the temperature information, and within the period of one cycle of the drive signal, when the drive signal transitions from the first voltage to the second voltage and maintains the second voltage for a certain period of time, the length of half a cycle of the clock signal is longer than the period of transition from the first voltage to the second voltage. The head unit according to feature 8.

11. The first comparator and the second comparator are composed of operational amplifiers or comparators. The head unit according to feature 8.

12. The aforementioned print head is A piezoelectric element comprising a first electrode, a second electrode, and a piezoelectric body, wherein in the stacking direction in which the first electrode, the second electrode, and the piezoelectric body are stacked, the piezoelectric body is positioned between the first electrode and the second electrode, and the piezoelectric element is driven by receiving the drive signal, A diaphragm is located on one side of the stacking direction relative to the piezoelectric element and deforms when the piezoelectric element is driven, A pressure chamber substrate is provided, located on one side of the diaphragm in the stacking direction, in which a liquid is stored and a pressure chamber whose volume changes due to the deformation of the diaphragm. A nozzle that discharges liquid in accordance with the change in volume of the pressure chamber, A temperature detection unit located on the other side of the stacking direction relative to the diaphragm, which outputs the head temperature signal corresponding to the temperature of the pressure chamber, Having, The head unit according to any one of claims 7 to 11.

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