Head unit and liquid ejection device

Abstract

A head unit and a liquid ejecting apparatus are provided. In the head unit, a first print head that ejects a liquid has a first piezoelectric element that receives a drive signal and is driven, a first vibration plate that is deformed by the drive of the first piezoelectric element, a first pressure chamber whose volume changes according to the deformation of the first vibration plate, a first nozzle that ejects the liquid according to the change in the volume of the first pressure chamber, and a first temperature detection portion that detects first temperature information corresponding to the temperature of the first pressure chamber and outputs the first temperature information as a first temperature signal. A temperature information output circuit that outputs a temperature information signal indicating the temperature of the first print head has a first amplification circuit that amplifies the difference between a first reference potential signal and the first temperature signal, an output control circuit that outputs a temperature information signal corresponding to the output of the first amplification circuit, and a reference voltage control circuit that controls the voltage value of the first reference potential signal.

Description

Technical Field

[0001] This invention relates to a head unit and a liquid ejection device. Background Technology

[0002] A known liquid ejection device comprises a printhead having a piezoelectric element, a pressure chamber, and a nozzle communicating with the pressure chamber. The printhead ejects liquid supplied to the pressure chamber from the nozzle by changing the volume of the pressure chamber through actuation of the piezoelectric element. In liquid ejection devices with such printheads, techniques are known for achieving ejection control at a temperature suitable for the ink by actuating the piezoelectric element based on the temperature of the ink stored in the printhead.

[0003] For example, Patent Document 1 discloses the following technology: by providing a temperature detection unit inside a printhead having a piezoelectric element, a pressure chamber and a nozzle to detect the temperature of the pressure chamber storing ink, the temperature difference between the temperature detected by the temperature detection unit and the temperature inside the pressure chamber can be reduced, thereby improving the detection accuracy of the temperature of the ink stored in the pressure chamber.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2022-124599

[0005] However, in a configuration where a temperature detection unit is provided inside the printhead, as in the liquid ejection device described in Patent Document 1, the technology described in Patent Document 1 is insufficient from the viewpoint of improving the accuracy of temperature acquisition of the printhead, and there is room for improvement. Summary of the Invention

[0006] One aspect of the head unit involved in this invention is a head unit that ejects liquid by receiving a drive signal corrected based on a temperature information signal, comprising:

[0007] A first printhead receives the drive signal and ejects liquid; and

[0008] The temperature information output circuit outputs a temperature information signal representing the temperature of the first printhead.

[0009] The first print head has:

[0010] The first piezoelectric element includes a first electrode, a second electrode, and a first piezoelectric body. In a first stacking direction in which the first electrode, the second electrode, and the first piezoelectric body are stacked, the first piezoelectric body is located between the first electrode and the second electrode and receives the driving signal to be driven.

[0011] The first vibrating plate is located on one side of the first piezoelectric element in the first stacking direction and is deformed by the drive of the first piezoelectric element;

[0012] The first pressure chamber substrate, located on one side of the first vibrating plate in the first stacking direction, is provided with a first pressure chamber whose volume varies according to the deformation of the first vibrating plate.

[0013] A first nozzle ejects liquid according to changes in the volume of the first pressure chamber; and

[0014] The first temperature detection unit, located on the opposite side of the first vibrating plate in the first stacking direction, detects first temperature information corresponding to the temperature of the first pressure chamber and outputs it as a first temperature signal.

[0015] The temperature information output circuit has the following features:

[0016] The first amplifier circuit amplifies the difference between the first reference potential signal and the first temperature signal;

[0017] The output control circuit outputs the temperature information signal corresponding to the output of the first amplifier circuit; and

[0018] The reference voltage control circuit controls the voltage value of the first reference potential signal.

[0019] One aspect of the liquid ejection device according to the present invention comprises:

[0020] The drive signal output circuit outputs a drive signal corrected based on temperature information; and

[0021] The head unit receives the drive signal and ejects liquid.

[0022] The head unit has:

[0023] A first printhead receives the drive signal and ejects liquid; and

[0024] The temperature information output circuit outputs a temperature information signal representing the temperature of the first printhead.

[0025] The first print head includes:

[0026] The first piezoelectric element includes a first electrode, a second electrode, and a first piezoelectric body. In a first stacking direction in which the first electrode, the second electrode, and the first piezoelectric body are stacked, the first piezoelectric body is located between the first electrode and the second electrode and receives the driving signal to be driven.

[0027] The first vibrating plate is located on one side of the first piezoelectric element in the first stacking direction and is deformed by the drive of the first piezoelectric element;

[0028] The first pressure chamber substrate, located on one side of the first vibrating plate in the first stacking direction, is provided with a first pressure chamber whose volume varies according to the deformation of the first vibrating plate.

[0029] A first nozzle ejects liquid according to changes in the volume of the first pressure chamber; and

[0030] The first temperature detection unit, located on the opposite side of the first vibrating plate in the first stacking direction, detects first temperature information corresponding to the temperature of the first pressure chamber and outputs it as a first temperature signal.

[0031] The temperature information output circuit includes:

[0032] The first amplifier circuit amplifies the difference between the first reference potential signal and the first temperature signal;

[0033] The output control circuit outputs the output of the first amplifier circuit as the temperature information signal; and

[0034] The reference voltage control circuit controls the voltage value of the first reference potential signal. Attached Figure Description

[0035] Figure 1 This is a diagram showing a simplified configuration of a liquid ejection device.

[0036] Figure 2 This is an exploded perspective view showing the structure of the print head.

[0037] Figure 3 This is a top view of the printhead when viewed along the Z-axis.

[0038] Figure 4 It is shown Figure 3 The cross-sectional view of section Aa is shown.

[0039] Figure 5 It is shown Figure 4 Details of the main parts, including the main part detail diagram.

[0040] Figure 6 It is shown Figure 3 The cross-sectional view of section Bb is shown.

[0041] Figure 7 This is a diagram showing the functional configuration of a liquid ejection device.

[0042] Figure 8 This is a diagram showing an example of the signal waveform of the drive signal COM.

[0043] Figure 9 This is a diagram showing the configuration of the drive signal selection circuit.

[0044] Figure 10 This is a diagram illustrating an example of the decoded content in the decoder.

[0045] Figure 11 This is a diagram showing the configuration of the selection circuit.

[0046] Figure 12 This is a diagram used to illustrate the operation of the drive signal selection circuit.

[0047] Figure 13 This diagram illustrates an example of the functional configuration of a temperature information output circuit.

[0048] Figure 14 This is a diagram showing a specific example of the configuration of an amplifier circuit.

[0049] Figure 15 This is a diagram illustrating an example of the relationship between the voltage value of the head temperature signal TC and the voltage value of the head temperature amplification signal ATC when an ideal head temperature signal TC is input to the amplifier circuit.

[0050] Figure 16 This is a diagram illustrating an example of a method for adjusting the voltage value of the reference potential signal Vref.

[0051] Figure 17 This is a diagram illustrating an example of the temperature control mechanism of a printhead.

[0052] Figure 18 This is a diagram showing an example of the head temperature amplification signal ATC output by the amplifier circuit before and after adjustment of the reference potential signal Vref.

[0053] Figure 19 This is another example of the head temperature amplification signal ATC output by the amplifier circuit before and after adjustment of the reference potential signal Vref.

[0054] Explanation of reference numerals in the attached figures

[0055] 1: Liquid ejection device; 10: Control unit; 20: Head unit; 21: Carriage; 22: Printhead; 24: Temperature detection circuit; 26: Temperature information output circuit; 28: Temperature detection circuit; 30: Moving unit; 31: Carriage motor; 32: Circular belt; 40: Conveying unit; 41: Conveying motor; 42: Conveying roller; 50: Drive circuit; 52: Reference voltage output circuit; 60: Piezoelectric element; 90: Ink container; 92: Linear encoder; 100: Control circuit; 200: Drive signal selection circuit; 210: Selection control circuit; 212: Shifting Register; 214: Latch circuit; 216: Decoder; 230: Selection circuit; 232: Inverter; 234: Transmission gate; 310: Pressure chamber substrate; 311: Partition plate; 312: Pressure chamber; 312a, 312b: Ends; 315: Connecting plate; 316: Nozzle connecting path; 317: First manifold section; 318: Second manifold section; 319: Supply connecting path; 320: Nozzle plate; 321: Nozzle; 330: Protective substrate; 331: Holding part; 332: Through hole; 340: Housing component; 341: Receiving part; 342: Third manifold section; 3 43: Connection port; 344: Supply port; 345: Flexible substrate; 346: Sealing film; 347: Fixed substrate; 348: Opening; 349: Flexible part; 350: Vibrating plate; 351: Elastic film; 352: Insulating film; 360: Electrode; 360a, 360b: End; 370: Piezoelectric element; 370a, 370b: End; 371: Groove; 380: Electrode; 380a, 380b: End; 385: Wiring part; 391: Single lead electrode; 392: Common lead electrode; 392a, 392b: Extension setting part; 393. 393a, 393b: Measurement lead electrodes; 400: Manifold; 401: Resistor wiring; 410: Active part; 415: Inactive part; 420: Wiring substrate; 421: Integrated circuit; 500: Control circuit; 502: Request parsing unit; 504: Temperature information output unit; 506: Memory control unit; 510: Amplifier circuit; 511-514: Resistors; 515: Operational amplifier; 520: Amplifier circuit; 530: Multiplexer; 540, 550: AD conversion circuit; 560: DA conversion circuit; 570: Storage circuit; P: Medium. Detailed Implementation

[0056] The preferred embodiments of the present invention will now be described using the accompanying drawings. The drawings are provided for ease of explanation. It should be noted that the embodiments described below do not unduly limit the scope of the invention as defined in the claims. Furthermore, not all elements described below are essential components of the present invention.

[0057] 1. Structure of the liquid ejection device

[0058] Structure of the liquid ejection device

[0059] Figure 1 This diagram shows a simplified configuration of the liquid ejection device 1. The liquid ejection device 1 of this embodiment is a serial printing inkjet printer in which a carriage 21 carrying a printhead 22 that ejects ink (an example of liquid) reciprocates along the scanning axis and ejects ink onto a medium P conveyed in the transport direction, thereby forming a desired image on the medium P. Furthermore, the medium P in the liquid ejection device 1 can be any printing material such as printing paper, resin film, or fabric. It should be noted that the liquid ejection device 1 is not limited to a serial printing inkjet printer; it can also be a line printing inkjet printer. Furthermore, the liquid ejection device 1 is not limited to an inkjet printer; it can also be a pigment ejection device used in the manufacture of color filters for liquid crystal displays, an electrode material ejection device used in the electrode formation of organic EL displays, FED (surface emission display), etc., a biological organic matter ejection device used in the manufacture of biochips, a three-dimensional modeling device, and a printing and dyeing device, etc.

[0060] Here, in the following explanation, three mutually orthogonal spatial axes, namely the X-axis, Y-axis, and Z-axis, will be used. Furthermore, in the following explanation, when determining the orientation along the X-axis, Y-axis, and Z-axis respectively, the tip of the arrow representing the direction along the X-axis in the illustration will be called the +X side, and the starting point side will be called the -X side; the tip of the arrow representing the direction along the Y-axis in the illustration will be called the +Y side, and the starting point side will be called the -Y side; the tip of the arrow representing the direction along the Z-axis in the illustration will be called the +Z side, and the starting point side will be called the -Z side.

[0061] Figure 1 The liquid ejection device 1 shown includes a control unit 10, a head unit 20, a moving unit 30, a conveying unit 40, and an ink container 90.

[0062] The ink container 90 stores various inks that are sprayed onto the medium P. The ink container 90 containing such inks can be an ink cartridge, a bag-shaped ink pouch formed of a flexible membrane, or an ink canister for refilling ink, etc.

[0063] The control unit 10 includes processing circuits such as a CPU (Central Processing Unit), an FPGA (Field Programmable Gate Array), and storage circuits such as a semiconductor memory, and controls the various elements of the liquid ejection device 1, including the head unit 20.

[0064] The print head unit 20 includes a carriage 21 and a plurality of print heads 22. The carriage 21 is fixed to an annular belt 32 included in the moving unit 30 (described later). The plurality of print heads 22 are mounted on the carriage 21. Furthermore, control signals Ctrl-H and drive signals COM, output by the control unit 10, are input to each of the plurality of print heads 22. Ink stored in the ink container 90 is then supplied to the plurality of print heads 22 via tubes (not shown). Based on the input control signals Ctrl-H and drive signals COM, the print heads 22 eject the ink supplied from the ink container 90. In this case, the direction in which the print heads 22 eject ink along the Z-axis, i.e., the direction along the Z-axis from the -Z side to the +Z side, is sometimes referred to as the ejection direction.

[0065] The moving unit 30 includes a carriage motor 31 and an annular belt 32. The carriage motor 31 operates based on a control signal Ctrl-C input from the control unit 10. The annular belt 32 extends along the X-axis and rotates with the operation of the carriage motor 31. As a result, the carriage 21, fixed to the annular belt 32, moves along the X-axis. That is, the moving unit 30 causes the plurality of printheads 22 mounted on the carriage 21 to reciprocate along the X-axis. Here, in the following description, the direction along the X-axis in which the plurality of printheads 22 mounted on the carriage 21 move is sometimes referred to as the scanning direction.

[0066] The conveying unit 40 includes a conveying motor 41 and a conveying roller 42. The conveying motor 41 operates based on a control signal Ctrl-T input from the control unit 10. The conveying roller 42 rotates along with the operation of the conveying motor 41 while holding the medium P. As a result, the medium P held by the conveying roller 42 is conveyed along the Y-axis from the -Y side to the +Y side. That is, the conveying unit 40 conveys the medium P along the Y-axis from the -Y side to the +Y side. Here, in the following description, the direction of conveying the medium P from the -Y side to the +Y side is sometimes referred to as the conveying direction.

[0067] In the liquid ejection device 1 configured as described above, the moving unit 30 controls the reciprocating movement of the carriage 21 along the scanning direction, and the conveying unit 40 controls the conveying of the medium P along the conveying direction. Furthermore, in conjunction with the reciprocating movement of the carriage 21 along the scanning direction and the conveying of the medium P in the conveying direction, the printhead 22 mounted on the carriage 21 ejects ink. As a result, the ink ejected by the printhead 22 can land on any surface of the medium P, forming a desired image on the medium P.

[0068] Printhead Structure

[0069] Next, an example of the structure of the print head 22 of the head unit 20 will be described. Figure 2 This is an exploded perspective view showing the structure of the print head 22. Figure 3 This is a top view of the print head 22 viewed along the Z-axis. Figure 4It is shown Figure 3 The cross-sectional view of section Aa shown. Figure 5 It is shown Figure 4 Details of the main parts, including the main part detail diagram. Figure 6 It is shown Figure 3 The cross-sectional view of section Bb is shown.

[0070] like Figure 2 As shown, the printhead 22 has a pressure chamber substrate 310, a connecting plate 315, a nozzle plate 320, a flexible substrate 345, a vibrating plate 350 (described later), a piezoelectric element 60 (described later), a protective substrate 330, a housing component 340, and a wiring substrate 420.

[0071] The pressure chamber substrate 310 is composed of, for example, a silicon substrate, a glass substrate, an SOI substrate, or various ceramic substrates. Figure 3 As shown, on the pressure chamber substrate 310, two rows of pressure chambers 312 arranged along the Y-axis are configured along the X-axis. Here, the pressure chamber row located on the +X side is sometimes referred to as the first pressure chamber row, and the pressure chamber row located on the -X side of the first pressure chamber row is referred to as the second pressure chamber row. It should be noted that... Figure 3 This is a top view of the printhead 22 viewed along the Z-axis, showing the peripheral structure of the pressure chamber substrate 310, while omitting the illustrations of the protective substrate 330, housing component 340, etc.

[0072] Furthermore, the multiple pressure chambers 312 constituting each pressure chamber row are arranged on a straight line along the Y-axis such that their positions along the X-axis are the same. Additionally, the pressure chambers 312 adjacent to each other along the Y-axis are... Figure 6 The partition 311 is shown as dividing the space. Of course, the arrangement of the pressure chambers 312 is not particularly limited; for example, the arrangement of multiple pressure chambers 312 along the Y-axis can also be a so-called staggered arrangement where the pressure chambers 312 are staggered every other one along the X-axis.

[0073] Furthermore, the pressure chamber 312 in this embodiment is formed as a rectangle, meaning its length along the X-axis is longer than its length along the Y-axis when viewed from the +Z side. Of course, the shape of the pressure chamber 312 when viewed from the +Z side is not limited to a rectangle; it can also be a parallelogram, a polygon, a circle, an ellipse, etc. Here, an ellipse refers to a shape based on a rectangle with semicircular ends along the long side, including rounded rectangular shapes, elliptical shapes, and egg shapes.

[0074] like Figure 2 As shown, a connecting plate 315, a nozzle plate 320, and a flexible substrate 345 are stacked on the +Z side of the pressure chamber substrate 310.

[0075] like Figure 2 , Figure 4 and Figure 5 As shown, a nozzle connection passage 316 connecting the pressure chamber 312 and the nozzle 321 is provided on the connecting plate 315. Additionally, a first manifold portion 317 and a second manifold portion 318, forming part of a manifold 400, are provided on the connecting plate 315. This manifold 400 serves as a common liquid chamber connected to the plurality of pressure chambers 312. The first manifold portion 317 extends through the connecting plate 315 in the Z-axis direction. The second manifold portion 318 does not extend through the connecting plate 315 in the Z-axis direction, but instead opens towards the +Z side.

[0076] Furthermore, on the connecting plate 315, a supply connecting passage 319, which connects to one end of the pressure chamber 312 in the X-axis direction, is provided independently of each pressure chamber 312. The supply connecting passage 319 connects the second manifold section 318 to each pressure chamber 312 and supplies ink from the manifold 400 to each pressure chamber 312.

[0077] The connecting plate 315 can be made of silicon substrate, glass substrate, SOI substrate, various ceramic substrates, metal substrates, etc. For example, stainless steel substrate can be used as a metal substrate. It should be noted that the connecting plate 315 is preferably made of a material with a thermal expansion coefficient approximately the same as that of the pressure chamber substrate 310. Therefore, even if the temperature of the pressure chamber substrate 310 and the connecting plate 315 changes, the possibility of warping of the pressure chamber substrate 310 and the connecting plate 315 due to differences in thermal expansion coefficients can be reduced.

[0078] The nozzle plate 320 is disposed on the opposite side of the pressure chamber base plate 310 of the connecting plate 315, i.e., the +Z side. Nozzles 321 are formed on the nozzle plate 320 and communicate with each pressure chamber 312 via nozzle connecting passages 316.

[0079] In this embodiment, the printhead 22 has a plurality of nozzles 321 arranged along the Y-axis. Specifically, on the nozzle plate 320, two rows of nozzles 321 arranged side-by-side are separated along the X-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 in each row are arranged in the same position along the X-axis. It should be noted that the arrangement of the nozzles 321 is not particularly limited; for example, the nozzles 321 arranged along the Y-axis may be arranged at positions offset along the X-axis, with every other nozzle being arranged at a position staggered.

[0080] The material of the nozzle plate 320 is not particularly limited; for example, silicon substrates, glass substrates, SOI substrates, various ceramic substrates, and metal substrates can be used. Furthermore, stainless steel substrates are an example of metal substrates. Additionally, organic materials such as polyimide resin can also be used as the material of the nozzle plate 320. Preferably, the nozzle plate 320 is made of a material with approximately the same coefficient of thermal expansion as the connecting plate 315. This reduces the possibility of warping of the nozzle plate 320 and the connecting plate 315 due to differences in their coefficients of thermal expansion, even when the temperatures of the nozzle plate 320 and the connecting plate 315 change.

[0081] The flexible substrate 345, together with the nozzle plate 320, is disposed on the opposite side of the pressure chamber substrate 310 of the connecting plate 315, i.e., the +Z side. The flexible substrate 345, disposed around the nozzle plate 320, seals the openings of the first manifold portion 317 and the second manifold portion 318 disposed on the connecting plate 315. The flexible substrate 345 includes a sealing film 346 made of a flexible thin film and a fixing substrate 347 made of a rigid material such as metal. Furthermore, the area of ​​the fixing substrate 347 opposite the manifold 400 becomes an opening 348 that is completely removed in the thickness direction. Therefore, one side of the manifold 400 becomes a flexible portion 349 sealed only by the flexible sealing film 346.

[0082] On the other hand, on the surface opposite to the nozzle plate 320, i.e., the -Z side, of the pressure chamber substrate 310, a vibrating plate 350 and a piezoelectric element 60 are stacked, which causes pressure changes in the ink within the pressure chamber 312 by flexing and deforming the vibrating plate 350. In other words, the vibrating plate 350 is disposed on the +Z side relative to the piezoelectric element 60 in the Z-axis direction, and the pressure chamber substrate 310 is disposed on the +Z side relative to the vibrating plate 350 in the Z-axis direction. It should be noted that... Figure 4 This diagram illustrates the overall structure of the printhead 22, simplifying the structure of the piezoelectric element 60.

[0083] Furthermore, a protective substrate 330 having approximately the same size as the pressure chamber substrate 310 is bonded to the -Z side surface of the pressure chamber substrate 310 using an adhesive or the like. The protective substrate 330 has a holding portion 331 that serves as a space for protecting the piezoelectric elements 60. The holding portion 331 is a space independently provided for each row of piezoelectric elements 60 arranged in the Y-axis direction, and two are formed in the X-axis direction. Additionally, a through hole 332 extending in the Z-axis direction is provided between the two holding portions 331 arranged in the X-axis direction on the protective substrate 330.

[0084] Additionally, a housing component 340 is fixed on the protective substrate 330, which, together with the pressure chamber substrate 310, divides the manifold 400 communicating with the plurality of pressure chambers 312. The housing component 340 has a shape substantially the same as the aforementioned connecting plate 315 when viewed from the -Z side, and is engaged with both the protective substrate 330 and the aforementioned connecting plate 315.

[0085] Such a housing component 340 has a receiving portion 341 on the protective substrate 330 side. This receiving portion 341 is a space with a depth capable of accommodating the pressure chamber substrate 310 and the protective substrate 330. The receiving portion 341 has an opening area larger than the surface of the protective substrate 330 that engages with the pressure chamber substrate 310. Furthermore, when the pressure chamber substrate 310 and the protective substrate 330 are accommodated in the receiving portion 341, the opening surface on the nozzle plate 320 side of the receiving portion 341 is sealed by the connecting plate 315.

[0086] Furthermore, third manifold sections 342 are respectively divided on both outer sides of the receiving portion 341 along the X-axis by the housing component 340. Additionally, the manifold 400 is formed by the first manifold section 317, the second manifold section 318, and the third manifold section 342 provided on the connecting plate 315. The manifold 400 is continuously arranged along the Y-axis, and the supply connecting passages 319 connecting each pressure chamber 312 to the manifold 400 are arranged along the Y-axis.

[0087] Additionally, a supply port 344 is provided on the housing component 340 for communicating with the manifold 400 and supplying ink to each manifold 400. Furthermore, a connection port 343 is provided on the housing component 340 for communicating with the through hole 332 of the protective substrate 330 and for inserting the wiring substrate 420.

[0088] The printhead 22 receives ink stored in the ink container 90 from the supply port 344. After the manifold 400 is filled with this ink to the nozzle 321, a signal based on the drive signal COM is supplied from the integrated circuit 421 to each piezoelectric element 60 corresponding to the pressure chamber 312. As a result, the vibrating plate 350 flexes and deforms together with the piezoelectric elements 60, increasing the pressure within each pressure chamber 312 and ejecting ink from each nozzle 321.

[0089] Next, the configuration including the aforementioned vibrating plate 350 and piezoelectric element 60, which is stacked on the -Z side of the pressure chamber substrate 310, will be described. As a configuration stacked on the -Z side of the pressure chamber substrate 310, in addition to the vibrating plate 350 and piezoelectric element 60, the printhead 22 also has a single lead electrode 391, a common lead electrode 392, a measurement lead electrode 393, and a resistor wiring 401.

[0090] like Figures 4-6As shown, the vibrating plate 350 comprises an elastic film 351 made of silicon oxide disposed on the pressure chamber substrate 310 side, and an insulating film 352 made of zirconium oxide disposed on the elastic film 351. The liquid flow channels of the pressure chamber 312, etc., are formed by anisotropic etching from the +Z side surface of the pressure chamber substrate 310, and the -Z side surface of the liquid flow channels of the pressure chamber 312, etc., is composed of the elastic film 351. It should be noted that the composition of the vibrating plate 350 is not particularly limited; for example, it can be composed of either the elastic film 351 or the insulating film 352, and may also include other films besides the elastic film 351 and the insulating film 352. Examples of materials for other films constituting the vibrating plate 350 include silicon and silicon nitride.

[0091] The piezoelectric element 60 functions as a piezoelectric actuator that causes pressure changes in the ink within the pressure chamber 312. This piezoelectric element 60 has electrodes 360, a piezoelectric body 370, and an electrode 380 stacked sequentially from the vibrating plate 350 side (+Z side) to the -Z side. In other words, the piezoelectric element 60 includes electrodes 360, 380, and a piezoelectric body 370, with the piezoelectric body 370 disposed between electrodes 360 and 380 in the Z-axis direction where the electrodes 360, 380, and 370 are stacked.

[0092] Electrodes 360 and 380 are both electrically connected to the wiring substrate 420. Furthermore, a signal supplied from the integrated circuit 421 mounted on the wiring substrate 420 is supplied to electrode 360, and a reference potential signal propagating in the wiring substrate 420 is supplied to electrode 380. Thus, the signal supplied from the integrated circuit 421 and the reference potential signal are supplied to the piezoelectric element 370. Additionally, the piezoelectric element 370 deforms due to the potential difference generated between electrodes 360 and 380. This deformation of the piezoelectric element 370 causes the vibrating plate 350 to deform or vibrate, resulting in a change in the volume of the pressure chamber 312. Furthermore, the pressure change caused by the change in the volume of the pressure chamber 312 is applied to the ink contained in the pressure chamber 312, causing the ink contained in the pressure chamber 312 to be ejected from the nozzle 321 via the nozzle connection 316. At this time, the amount of ink ejected from the nozzle 321 is equal to the change in the volume of the pressure chamber 312.

[0093] In the following description, the portion of the piezoelectric element 60 that generates piezoelectric strain in the piezoelectric body 370 when a voltage is applied between electrodes 360 and 380 is referred to as the active portion 410, and the portion of the piezoelectric body 370 that does not generate piezoelectric strain is referred to as the inactive portion 415. That is, the portion of the piezoelectric element 60 where 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, when the piezoelectric element 60 is driven, the portion that displaces in the Z-axis direction is referred to as the flexible portion, and the portion that does not displace in the Z-axis direction is referred to as the non-flexible portion. That is, the portion of the piezoelectric element 60 opposite the pressure chamber 312 in the Z-axis direction corresponds to the flexible portion, and the outer portion of the pressure chamber 312 corresponds to the non-flexible portion. It should be noted that the active part 410 is sometimes referred to as the active part, and the inactive part 415 is sometimes referred to as the passive part.

[0094] Generally, each electrode of the active part 410 is configured as a single electrode independent for each active part 410, and the other electrode is configured as a common electrode shared by multiple active parts 410. In this embodiment, the electrode 360, which supplies the signal output by the integrated circuit 421, is configured as a single electrode, and the electrode 380, which supplies the signal of the reference potential propagating in the wiring substrate 420, is configured as a common electrode.

[0095] Specifically, the electrode 360 ​​is disposed on the +Z side relative to the piezoelectric element 370, forming a single electrode that is divided for each pressure chamber 312 and independent for each active part 410. That is, the electrode 360 ​​is disposed individually relative to the plurality of pressure chambers 312. In the direction along the Y-axis, the electrode 360 ​​is formed with a width narrower than the width of the pressure chamber 312. That is, in the direction along the Y-axis, the end of the electrode 360 ​​is located inside the region opposite to the pressure chamber 312.

[0096] Furthermore, the +X side end 360a and the -X side end 360b of the electrode 360 ​​are respectively disposed on the outside of the pressure chamber 312. For example, in the first pressure chamber row, such as Figure 5 As shown, end 360a of electrode 360 ​​is positioned further to the +X side than end 312a on the +X side of pressure chamber 312. End 360b of electrode 360 ​​is positioned further to the -X side than end 312b on the -X side of pressure chamber 312.

[0097] The material of 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) can be used. Alternatively, multiple materials such as platinum (Pt), iridium (Ir), gold (Au), and titanium (Ti) can be layered to form the electrode. In this embodiment, platinum (Pt) is used as electrode 360.

[0098] like Figure 3 As shown, the piezoelectric element 370 has a predetermined length along the X-axis and is continuously arranged along the Y-axis. That is, the piezoelectric element 370 is continuously arranged with a predetermined thickness along the side-by-side arrangement direction of the pressure chamber 312. The thickness of the piezoelectric element 370 is not particularly limited and is formed with a thickness of about 1000 nanometers to 4000 nanometers.

[0099] In addition, such as Figure 5 As shown, 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 its longer side. Therefore, the piezoelectric element 370 extends to the outside of the pressure chamber 312 on both sides along the X-axis. By extending the piezoelectric element 370 to the outside of the pressure chamber 312 along the X-axis, the strength of the vibrating plate 350 is increased. Therefore, when the piezoelectric element 60 is displaced by driving the active part 410, the possibility of cracks or other defects in the vibrating plate 350 or the piezoelectric element 60 can be reduced.

[0100] Additionally, for example, in the first pressure chamber row, such as Figure 5 As shown, the +X side end 370a of the piezoelectric body 370 is located on the +X side further outward than the end 360a of the electrode 360. That is, the end 360a of the electrode 360 ​​is covered by the piezoelectric body 370. On the other hand, the -X side end 370b of the piezoelectric body 370 is located on the +X side further inward than the end 360b of the electrode 360, and the end 360b of the electrode 360 ​​is not covered by the piezoelectric body 370.

[0101] It should be noted that, as Figure 3 and Figure 6 As shown, grooves 371, which are thinner than other regions, are formed on the piezoelectric body 370 corresponding to each partition 311. In this embodiment, the grooves 371 are formed by completely removing the piezoelectric body 370 in the Z-axis direction. That is, the piezoelectric body 370 having a thinner thickness than other regions means that the piezoelectric body 370 is completely removed in the Z-axis direction. Of course, the piezoelectric body 370 can also be formed thinner than other regions on the bottom surface of the grooves 371.

[0102] Furthermore, the length of the groove 371 along the Y-axis, i.e., the width of the groove 371, is the same as or wider than the width of the partition 311. In this embodiment, the width of the groove 371 is wider than the width of the partition 311. When viewed from the -Z side, such a groove 371 is rectangular. Of course, the shape of the groove 371 when viewed from the -Z side is not limited to a rectangular shape; it can also be a polygon with more than one pentagon, or a circular or elliptical shape, etc.

[0103] By providing a groove 371 on the piezoelectric element 370, the rigidity of the portion of the vibrating plate 350 that is opposite to the end of the pressure chamber 312 in the Y-axis direction, i.e., the arm portion of the vibrating plate 350, can be suppressed, thus enabling the piezoelectric element 60 to be displaced more effectively.

[0104] Examples of piezoelectric materials 370 include perovskite-structured crystal films formed on electrodes 360, which are composed of ferroelectric ceramic materials representing electromechanical conversion. Materials used for the piezoelectric material 370 include, for example, ferroelectric piezoelectric materials such as lead zirconate titanate (PZT), and materials to which metal oxides such as niobium oxide, nickel oxide, or magnesium oxide have been added. Specifically, lead titanate (PbTiO3), lead zirconate titanate (Pb(Zr,Ti)O3), lead zirconate (PbZrO3), lanthanum lead titanate ((Pb,La),TiO3), lanthanum lead zirconate titanate ((Pb,La)(Zr,Ti)O3), or lead magnesium zirconate titanate (Pb(Zr,Ti)(Mg,Nb)O3) can be used. In this embodiment, lead zirconate titanate (PZT) is used as the piezoelectric material 370.

[0105] Furthermore, the material used for the piezoelectric element 370 is not limited to lead-based piezoelectric materials containing lead; lead-free non-lead piezoelectric materials can also be used. Examples of lead-free piezoelectric materials include bismuth ferrite ((BiFeO3, abbreviated as "BFO")), barium titanate ((BaTiO3, abbreviated as "BT")), potassium sodium niobate ((K,Na)(NbO3, abbreviated as "KNN")), lithium potassium sodium niobate ((K,Na,Li)(NbO3)), lithium potassium sodium niobate ((K,Na,Li)(Nb,Ta)O3), potassium bismuth potassium titanate ((Bi1 / 2K1 / 2)TiO3, abbreviated as "BKT"), sodium bismuth titanate ((Bi1 / 2Na1 / 2)TiO3, abbreviated as "BNT"), and bismuth manganate (…). BiMnO3 (abbreviated as "BM"), composite oxides containing bismuth, potassium, titanium and iron with a perovskite structure (x[(BixK1-x)TiO3]-(1-x)[BiFeO3], abbreviated as "BKT-BF"), composite oxides containing bismuth, iron, barium and titanium with a perovskite structure ((1-x)[BiFeO3]-x[BaTiO3], abbreviated as "BFO-BT"), and materials with added manganese, cobalt, chromium and other metals ((1-x)[Bi(Fe1-yMy)O3]-x[BaTiO3] (M is Mn, Co or Cr)), etc.

[0106] like Figure 3 , Figure 5 and Figure 6 As shown, electrode 380 is disposed on the -Z side opposite to electrode 360, relative to piezoelectric body 370, forming a common electrode shared by multiple active parts 410. That is, electrode 380 is disposed for multiple pressure chambers 312. Electrode 380 is disposed with a predetermined length along the X-axis and is continuously disposed along the Y-axis. Electrode 380 is also disposed on the inner surface of groove 371, i.e., on the side surface of groove 371 of piezoelectric body 370 and on insulating film 352 which is the bottom surface of groove 371. It should be noted that, regarding the groove 371, electrode 380 may be disposed only on a portion of the inner surface of groove 371, or may not be disposed on the entire inner surface of groove 371.

[0107] Additionally, for example, in the first pressure chamber row, such as Figure 5As shown, the +X side end 380a of electrode 380 is positioned further outward than the end 360a of electrode 360 ​​covered by piezoelectric body 370. That is, the end 380a of electrode 380 is located on the +X side further outward than the end 312a of pressure chamber 312, and also on the +X side further outward than the end 360a of electrode 360. In this embodiment, the end 380a of electrode 380 substantially coincides with the end 370a of piezoelectric body 370 in the X-axis direction. Therefore, the +X side end of active portion 410, i.e., the boundary between active portion 410 and inactive portion 415, is defined by the end 360a of electrode 360.

[0108] On the other hand, the -X side end 380b of electrode 380 is disposed on the -X side, which is further outward than the -X side end 312b of pressure chamber 312, and further inward than the end 370b of piezoelectric body 370. As described above, the end 370b of piezoelectric body 370 is located on the inner side, which is further inward than the end 360b of electrode 360. Therefore, the end 380b of electrode 380 is located on piezoelectric body 370, which is further inward than the end 360b of electrode 360. Therefore, on the -X side of end 380b of electrode 380, there is a portion of the surface of piezoelectric body 370 exposed.

[0109] In this way, the end 380b of electrode 380 is positioned further towards the +X side than the end 370b of piezoelectric body 370 and the end 360b of electrode 360. Therefore, the end of active part 410 on the -X side, that is, the boundary between active part 410 and inactive part 415, is defined by the end 380b of electrode 380.

[0110] The material of electrode 380 is not particularly limited, but similar to electrode 360, it can be a conductive material such as metals like platinum (Pt), iridium (Ir), gold (Au), and titanium (Ti), or conductive metal oxides such as indium tin oxide (ITO). Alternatively, it can be formed by layering multiple materials such as platinum (Pt), iridium (Ir), gold (Au), and titanium (Ti). In this embodiment, iridium (Ir) is used as electrode 380.

[0111] Furthermore, a wiring portion 385, which is on the outer side of the end 380b of the electrode 380, that is, further towards the -X side than the end 380b of the electrode 380, is provided. This wiring portion 385 is formed from the piezoelectric body 370 to the electrode 360, which extends further towards the -X side than the piezoelectric body 370, with a gap between it and the end 380b of the electrode 380. This wiring portion 385 is provided independently for each active portion 410. That is, multiple wiring portions 385 are arranged at predetermined intervals along the Y-axis. It should be noted that the wiring portion 385 may also be formed from a different layer than the electrode 380, but it is preferable that it is formed from the same layer as the electrode 380. This simplifies the manufacturing process of the wiring portion 385 and reduces costs.

[0112] Furthermore, on the electrodes 360 and 380 constituting the piezoelectric element 60, a single lead electrode 391 is connected to the electrode 360, and a common lead electrode 392 serving as a common driving electrode is electrically connected to the electrode 380. A flexible wiring substrate 420 is electrically connected to the ends of the single lead electrode 391 and the common lead electrode 392 opposite to the ends connected to the piezoelectric element 60. Multiple wirings for connecting to the control unit 10, the temperature information output circuit 26, and multiple circuits (not shown) are formed on the wiring substrate 420. In this embodiment, the wiring substrate 420 is, for example, constructed from an FPC (Flexible Printed Circuit). It should be noted that an FPC can be used instead of an FPC, and any flexible substrate such as an FFC (Flexible Flat Cable) can be used.

[0113] In this embodiment, the individual lead electrode 391 and the common lead electrode 392 extend and are exposed within a through-hole 332 formed in the protective substrate 330, and are electrically connected to the wiring substrate 420 within the through-hole 332. Additionally, an integrated circuit 421 for outputting signals for driving the piezoelectric element 60 is mounted on the wiring substrate 420.

[0114] In this embodiment, the individual lead electrode 391 and the common lead electrode 392 are formed from the same layer, but are electrically discontinuous. Therefore, compared to forming the individual lead electrode 391 and the common lead electrode 392 separately, the manufacturing process can be simplified and costs reduced. Of course, the individual lead electrode 391 and the common lead electrode 392 can also be formed from different layers.

[0115] The materials used for the individual lead electrode 391 and the common lead electrode 392 are not particularly limited, as long as they are conductive. For example, gold (Au), copper (Cu), titanium (Ti), tungsten (W), nickel (Ni), chromium (Cr), platinum (Pt), and aluminum (Al) can be used. In this embodiment, gold (Au) is used as both the individual lead electrode 391 and the common lead electrode 392. Furthermore, the individual lead electrode 391 and the common lead electrode 392 may also have an adhesive layer that improves adhesion to the electrode 360, the electrode 380, or the vibrating plate 350.

[0116] Each lead electrode 391 is provided for each active part 410, i.e., each electrode 360. For example... Figure 5 As shown, for example, in the first pressure chamber array, a single lead electrode 391 is connected via a wiring portion 385 to the vicinity of the end 360b of the electrode 360 ​​disposed on the outside of the piezoelectric body 370, and is led out in the -X direction to the pressure chamber substrate 310, which is actually the vibrating plate 350.

[0117] On the other hand, such as Figure 3 As shown, for example, in the first pressure chamber array, at both ends along the Y-axis, a common lead electrode 392 extends from the electrode 380 constituting the common electrode on the piezoelectric body 370 toward the -X side to the vibrating plate 350. Furthermore, the common lead electrode 392 has an extension portion 392a and an extension portion 392b. (As shown...) Figure 3 , Figure 5 As shown, for example, in the first pressure chamber row, the extension portion 392a extends along the Y-axis in the region corresponding to the end 312a of the pressure chamber 312, and the extension portion 392b extends along the Y-axis in the region corresponding to the end 312b of the pressure chamber 312. These extension portions 392a and 392b are continuously arranged relative to the plurality of active portions 410 in the Y-axis direction.

[0118] Furthermore, the extension portions 392a and 392b extend from the inside of the pressure chamber 312 to the outside of the pressure chamber 312 in the X-axis direction. 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 X-axis direction, and the extension portions 392a and 392b extend from the active portion 410 to the outside of the pressure chamber 312.

[0119] like Figure 5As shown, a resistance wire 401 is provided on the -Z side surface of the vibrating plate 350. The resistance wire 401 detects the temperature of the pressure chamber 312 by utilizing the characteristic that the resistance value changes with temperature. As a material for such a resistance wire 401, materials with temperature-dependent resistance values ​​can be used, such as gold (Au), platinum (Pt), iridium (Ir), aluminum (Al), copper (Cu), titanium (Ti), tungsten (W), nickel (Ni), chromium (Cr), etc. Among them, platinum (Pt) has a large resistance value change with temperature, and also has high stability and accuracy. Furthermore, platinum (Pt) has a high linearity in the change of resistance value with temperature. From this point of view, platinum (Pt) is preferably used as the material for the resistance wire 401. That is, it is preferable that the resistance wire 401 is composed of platinum (Pt). In addition, in this embodiment, the resistance wire 401 is formed on the -Z side surface of the vibrating plate 350 in a manner that is co-layered with the electrode 360 ​​and electrically discontinuous with the electrode 360. That is, the resistive wiring 401 includes a wiring pattern on the -Z side of the vibrating plate 350 along the Z-axis direction, the wiring pattern containing platinum (Pt).

[0120] like Figure 3 As shown, 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 substrate 420. Thus, a voltage signal corresponding to the resistance value is output from the printhead 22, and this resistance value varies according to the temperature of the pressure chamber 312 detected by the resistance wiring 401. In this embodiment, the resistance wiring 401 is covered by a piezoelectric element 370 and is located between the vibrating plate 350 and the piezoelectric element 370 in the Z-axis direction.

[0121] The resistor wiring 401 includes a first pressure chamber row side serpentine pattern located on the +X side along the X-axis and a second pressure chamber row side serpentine pattern located on the -X side along the X-axis. Viewed from the -Z side, the first pressure chamber row side serpentine pattern is located at a position overlapping with the supply connection path 319, serpentine in the Y-axis direction, and the supply connection path 319 communicates with each pressure chamber 312 constituting the first pressure chamber row. Viewed from the -Z side, the second pressure chamber row side serpentine pattern is located at a position overlapping with the supply connection path 319, serpentine in the Y-axis direction, and the supply connection path 319 communicates with each pressure chamber 312 constituting the second pressure chamber row. That is, the resistor wiring 401 includes a first pressure chamber row side serpentine pattern corresponding to the first pressure chamber row formed by the plurality of pressure chambers 312, and a second pressure chamber row side serpentine pattern corresponding to the second pressure chamber row formed by the plurality of pressure chambers 312.

[0122] In addition, such as Figure 4 , Figure 5 As shown, the distance between the -Z side end of pressure chamber 312 and the resistor wiring 401 along the Z-axis is shorter than the dimension of pressure chamber 312 along the Z-axis. Furthermore, for example, in the first pressure chamber row, the longest distance between the +X side end 312a of pressure chamber 312 and the resistor wiring 401 along the X-axis is shorter than the dimension of pressure chamber 312 along the X-axis. Therefore, the resistance value of resistor wiring 401 easily changes in response to temperature changes in pressure chamber 312.

[0123] In this embodiment, the measuring lead electrode 393, including measuring lead electrode 393a and measuring lead electrode 393b, is formed in the same layer as the individual lead electrode 391 and the common lead electrode 392, but is electrically discontinuous. Therefore, compared to forming the measuring lead electrode 393, the individual lead electrode 391, and the common lead electrode 392 individually, the manufacturing process can be simplified and costs reduced. Of course, the measuring lead electrode 393 can also be formed from a different layer than the individual lead electrode 391 and the common lead electrode 392.

[0124] The material of the measuring lead electrode 393 is not particularly limited, as long as it is a conductive material. For example, gold (Au), copper (Cu), titanium (Ti), tungsten (W), nickel (Ni), chromium (Cr), platinum (Pt), and aluminum (Al) can be used. In this embodiment, gold (Au) is used as the measuring lead electrode 393. Therefore, the material of the measuring lead electrode 393 is the same as that of the individual lead electrode 391 and the common lead electrode 392. In addition, the measuring lead electrode 393 may also have an adhesive layer to improve adhesion to the resistance wiring 401 or the oscillating plate 350.

[0125] As described above, in this embodiment, the measuring lead electrode 393 extends and protrudes into the through-hole 332 formed in the protective substrate 330, and is electrically connected to the wiring substrate 420 within the through-hole 332. Thus, the resistance value of the resistive wiring 401, which varies according to the temperature of the pressure chamber 312, is output from the printhead 22 via the wiring substrate 420.

[0126] That is, the printhead 22 of the printhead unit 20 in this embodiment includes: a piezoelectric element 60, including electrodes 360, 380 and piezoelectric body 370, with the piezoelectric body 370 located between electrodes 360 and 380 in the Z-axis direction where electrodes 360, 380 and piezoelectric body 370 are stacked, and is driven by receiving a drive signal COM; a vibrating plate 350, located on the +Z side of the Z-axis direction relative to the piezoelectric element 60, and deformed by the drive of the piezoelectric element 60; a pressure chamber substrate 310, located on the +Z side of the Z-axis direction relative to the vibrating plate 350, and provided with a pressure chamber 312 whose volume changes according to the deformation of the vibrating plate 350; a nozzle 321, which ejects ink according to the change in volume of the pressure chamber 312; and a resistor wiring 401, located on the -Z side of the Z-axis direction relative to the vibrating plate 350, and obtaining a temperature corresponding to the temperature of the pressure chamber 312.

[0127] 2. Functional Composition of Liquid Ejection Device

[0128] Functional components of a liquid ejection device

[0129] Next, the functional configuration of the liquid ejection device 1 will be explained. Figure 7 This is a diagram showing the functional configuration of the liquid ejection device 1. (See diagram below.) Figure 7 As shown, the liquid ejection device 1 includes a control unit 10, a head unit 20, a carriage motor 31, a conveyor motor 41, and a linear encoder 92.

[0130] 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, processing circuits such as a CPU or FPGA, and storage circuits such as semiconductor memory. Image information signals, including image data, are input to the control circuit 100 from external devices such as a host computer that are communicatively connected to the liquid ejection device 1. Based on the input image information signals, the control circuit 100 generates various signals for controlling the liquid ejection device 1 and outputs them to the corresponding components.

[0131] As a specific example, in the control circuit 100, in addition to the aforementioned image information signal, a detection signal based on the scanning position of the carriage 21 included in the head unit 20 is also input from the linear encoder 92. Thus, the control circuit 100 determines the scanning position of the carriage 21, that is, the scanning position of the head unit 20 including the print head 22. Furthermore, the control circuit 100 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 components.

[0132] In detail, the control circuit 100 generates a control signal Ctrl-C for controlling the movement of the head unit 20 along the scanning axis based on the scanning position of the head unit 20, and outputs it to the carriage motor 31. As a result, the carriage motor 31 operates, controlling the movement and scanning position of the head unit 20 mounted on the carriage 21 along the scanning axis. Additionally, the control circuit 100 generates a control signal Ctrl-T for controlling the transport of the medium P, and outputs it to the transport motor 41. As a result, the transport motor 41 operates, controlling the movement of the medium P along the transport direction. It should be noted that the control signal Ctrl-C can also be input to the carriage motor 31 after signal conversion via a driver circuit (not shown), and the control signal Ctrl-T can also be input to the transport motor 41 after signal conversion via a driver circuit (not shown).

[0133] Furthermore, the control circuit 100 generates printing data signals SI1 to SIn, a change signal CH, a latch signal LAT, and a clock signal SCK as a control signal Ctrl-H for controlling the print head 20 based on the image information signal input from an external device and the scanning position of the print head 20, and outputs them to the print head 20. Next, the control circuit 100 generates a temperature acquisition request signal TD at a predetermined timing to acquire the temperature of the print head 20, and outputs it to the print head 20. At this time, a temperature information signal TI, including the temperature of the print head 20 corresponding to the temperature acquisition request signal TD, is input to the control circuit 100. Based on the input temperature information signal TI, the control circuit 100 grasps the state of the print head 20, corrects the control signals Ctrl-H, Ctrl-C, and Ctrl-T, and outputs them to the corresponding components. Thus, the operation of the liquid ejection device 1 and the print head 20 is controlled according to the temperature of the print head 22, i.e., the temperature information signal TI. As a result, the ink ejection accuracy from the liquid ejection device 1 and the print head 20 is improved.

[0134] Additionally, the control circuit 100 generates a base drive signal dA1 as a digital signal, which is then used as the control signal Ctrl-H and output to the drive circuit 50. The drive circuit 50 generates a drive signal COM with a signal waveform defined by the base drive signal dA1, which is then used as the drive signal COM and output to the head unit 20.

[0135] Specifically, the base drive signal dA1 output by the control circuit 100 is input to the drive circuit 50. After converting the input base drive signal dA1 into a digital-to-analog signal, the drive circuit 50 generates a drive signal COM by performing Class D amplification on the converted analog signal and outputs it to the head unit 20. That is, the control circuit 100 outputs the base drive signal dA1 as the control signal Ctrl-H corrected based on the temperature information signal TI, and the drive circuit 50 outputs the corrected drive signal COM corresponding to the base drive signal dA1 corrected based on the temperature information signal TI. Here, the base drive signal dA1 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 dA1 can be an analog signal as long as it can define the signal waveform of the drive signal COM. In addition, the drive circuit 50 can also generate the drive signal COM by performing Class A amplification, Class B amplification, or Class AB amplification on the signal waveform defined by the base drive signal dA1.

[0136] 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 constant voltage value that serves as a reference for driving the piezoelectric element 60 and is supplied to the electrode 380, which serves as a common electrode. The voltage value of such a reference voltage signal VBS can be, for example, a constant signal at ground potential, or a constant potential such as 5.5V or 6V.

[0137] The head unit 20 includes printheads 22-1 to 22-n, which are multiple printheads 22, a temperature information output circuit 26, and a temperature detection circuit 28. In addition, printheads 22-1 to 22-n each include a drive signal selection circuit 200, a temperature detection circuit 24, and multiple piezoelectric elements 60.

[0138] 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 output from 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. Based on the input clock signal SCK, latch signal LAT, change signal CH, and print data signal SI1, the drive signal selection circuit 200 generates drive signals VOUT corresponding to the multiple piezoelectric elements 60 by selecting or not selecting the signal waveforms included in the drive signal COM. Furthermore, the drive signal selection circuit 200 outputs the generated drive signals VOUT to one end of each corresponding piezoelectric element 60, i.e., electrode 360, which serves as a single electrode. Additionally, the reference voltage signal VBS is input to the other end of the multiple piezoelectric elements 60, i.e., electrode 380, which serves as a common electrode. Furthermore, the multiple piezoelectric elements 60 are displaced by the potential difference between the drive signal VOUT input to the electrode 360 ​​and the reference voltage signal VBS input to the electrode 380. Consequently, an amount of ink corresponding to the displacement of the piezoelectric elements 60 is ejected from the corresponding nozzles 321 of the printhead 22-1. Here, at least a portion of the drive signal selection circuit 200 of the printhead 22-1 is mounted as the aforementioned integrated circuit 421 on the wiring substrate 420 of the printhead 22-1.

[0139] Furthermore, the temperature detection circuit 24 of the printhead 22-1 detects the temperature of the printhead 22-1. The temperature detection circuit 24 also acquires printhead temperature information tc1, which is a voltage value corresponding to the detected temperature of the printhead 22-1, and outputs a printhead temperature signal TC1, including the acquired printhead temperature information tc1, to the temperature information output circuit 26. Here, at least a portion of the temperature detection circuit 24 of the printhead 22-1 is provided in the printhead 22-1 as the aforementioned resistor wiring 401. That is, the printhead temperature information tc1, which is a voltage value corresponding to the temperature of the printhead 22-1, output by the temperature detection circuit 24, includes information about the voltage value that changes according to the resistance value of the resistor wiring 401, which changes with temperature.

[0140] Furthermore, printheads 22-2 to 22-n differ only in the input and output signals, performing the same operations as printhead 22-1. Specifically, a clock signal SCK, a latch signal LAT, a change signal CH, a print data signal SIi, a drive signal COM, and a reference voltage signal VBS are input to printhead 22-i (i being any one of 2 to n). Additionally, the drive signal selection circuit 200 of printhead 22-i, based on the input clock signal SCK, latch signal LAT, change signal CH, and print data signal SIi, generates drive signals VOUT corresponding to the plurality of piezoelectric elements 60 by selecting or not selecting the signal waveform of the drive signal COM, and outputs these signals to the electrodes 360 of the corresponding piezoelectric elements 60. Furthermore, the reference voltage signal VBS is input to the electrodes 380 of the plurality of piezoelectric elements 60 in printhead 22-i. Therefore, the multiple piezoelectric elements 60 of the printhead 22-i are driven, and an amount of ink corresponding to the driving of the piezoelectric elements 60 is ejected from the nozzle 321 of the printhead 22-i. Additionally, the temperature detection circuit 24 of the printhead 22-i acquires printhead temperature information tci, which is a voltage value corresponding to the temperature of the printhead 22-i, and outputs a printhead temperature signal TCi, including the acquired printhead temperature information tci, to the temperature information output circuit 26. Here, at least a portion of the drive signal selection circuit 200 of the printhead 22-i is mounted as the aforementioned integrated circuit 421 on the wiring substrate 420 of the printhead 22-i, and at least a portion of the temperature detection circuit 24 of the printhead 22-i is provided as the aforementioned resistive wiring 401 on the printhead 22-i.

[0141] In the following description, we will explain the process of inputting 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 to the print head 22 when there is no need to distinguish between print heads 22-1 to 22-n. Furthermore, we will explain the process of the print head 22's temperature detection circuit 24 acquiring print head temperature information tc (as voltage values ​​corresponding to the temperature of the print head 22), and the print head 22 outputting print head temperature signals TC (as print head temperature signals TC1 to TCn) that include the acquired print head temperature information tc.

[0142] Temperature detection circuit 28 detects the temperature of the printhead units 20, including printheads 22-1 to 22-n. Furthermore, temperature detection circuit 28 generates a unit temperature signal TH, which includes unit temperature information th including a voltage value corresponding to the detected temperature. Temperature detection circuit 28 outputs the generated unit temperature signal TH to temperature information output circuit 26 and control circuit 100. This temperature detection circuit 28 is configured including a thermistor element, the resistance of which changes according to the temperature change of the printhead units 20.

[0143] The temperature information output circuit 26 receives the head temperature signals TC1 to TCn output by the print heads 22-1 to 22-n respectively, the unit temperature signal TH output by the temperature detection circuit 28, and the temperature acquisition request signal TD output by the control circuit 100.

[0144] The temperature information output circuit 26 corrects and amplifies the head temperature signals TC1 to TCn based on the unit temperature information th included in the unit temperature signal TH. Then, the temperature information output circuit 26 outputs the signals based on the head temperature information tc1 to tcn corresponding to the temperature acquisition request signal TD input from the control circuit 100 as temperature information signals TI to the control circuit 100. It should be noted that a specific example of the structure and operation of the temperature information output circuit 26 will be described later.

[0145] As described above, in the liquid ejection device 1 of this embodiment, the control circuit 100 outputs a control signal Ctrl-H including a clock signal SCK corrected based on the temperature information signal TI, a latch signal LAT, a change signal CH, and a print data signal SI. The drive circuit 50 outputs a drive signal COM corrected based on the temperature information signal TI. The head unit 20 receives the control signal Ctrl-H and the drive signal COM and ejects ink. Furthermore, the head unit 20 includes printheads 22-1 to 22-n that receive the drive signal COM and eject ink, and a temperature information output circuit 26 that outputs a temperature information signal TI representing the temperature of the printheads 22-1 to 22-n.

[0146] The signal waveform of the drive signal COM and the functional composition of the drive signal selection circuit

[0147] Next, the configuration and operation of the drive signal selection circuit 200 of the printhead 22 will be explained. As described above, the drive signal selection circuit 200 of the printhead 22 generates a drive signal VOUT by selecting or not selecting 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. Therefore, when explaining the configuration and operation of the drive signal selection circuit 200, an example of the waveform of the drive signal COM input to the drive signal selection circuit 200 will be explained first.

[0148] Figure 8 This is a diagram illustrating an example of the signal waveform of the drive signal COM. (As shown...) Figure 8As shown, the drive signal COM includes: a trapezoidal waveform Adp, configured during the period t1 from the rise of the latch signal LAT to the rise of the change signal CH; a trapezoidal waveform Bdp, configured during the period t2 from the rise of the change signal CH to the next rise of the change signal CH; and a trapezoidal waveform Cdp, configured during the period t3 from the rise of the change signal CH to the rise of the latch signal LAT. The trapezoidal waveform Adp is a signal waveform that drives the piezoelectric element 60 to eject a predetermined amount of ink, the trapezoidal waveform Bdp is a signal waveform that drives the piezoelectric element 60 to eject a smaller amount of ink than the predetermined amount, and the trapezoidal waveform Cdp is a signal waveform that drives the piezoelectric element 60 to achieve a level where no ink is ejected. Here, when the trapezoidal waveform Cdp is supplied to the piezoelectric element 60, the piezoelectric element 60 is a signal waveform used to reduce the possibility of increased ink viscosity near the nozzle orifice by causing vibration of the ink near the corresponding nozzle orifice.

[0149] Furthermore, the trapezoidal waveforms Adp, Bdp, and Cdp are signal waveforms whose voltage values ​​are identical at both the start and end of their respective timing intervals. That is, the trapezoidal waveforms Adp, Bdp, and Cdp begin and end with voltage Vc, respectively.

[0150] In the following description, the amount of ink ejected in accordance with a predetermined quantity when a trapezoidal waveform Adp is supplied to the piezoelectric element 60 is sometimes referred to as a medium quantity, and the amount of ink ejected less than the predetermined quantity when a trapezoidal waveform Bdp is supplied to the piezoelectric element 60 is sometimes referred to as a small quantity. Furthermore, the action used to vibrate the ink near the nozzle opening corresponding to the piezoelectric element 60 to prevent an increase in ink viscosity when a trapezoidal waveform Cdp is supplied to the piezoelectric element 60 is sometimes referred to as micro-vibration. It should be noted that... Figure 8 The waveform of the drive signal COM shown is just one example and is not limited to it. The waveform of the drive signal COM can also be varied by different combinations of waveforms depending on the properties of the ink being sprayed and the material of the medium P on which the ink lands.

[0151] Furthermore, the drive signal selection circuit 200 selects or deselects the trapezoidal waveforms Adp, Bdp, and Cdp included in the drive signal COM during the period tp, which includes periods t1, t2, and t3. Thus, the drive signal selection circuit 200 controls the amount of ink ejected from the multiple nozzles 321 during the period tp. That is, the drive signal selection circuit 200 controls the size of the dots formed on the medium P during the period tp. During the period tp, which includes periods t1, t2, and t3, dots of a predetermined size are formed on the medium P. The period tp in which the dots of this predetermined size are formed corresponds to the dot formation period.

[0152] Next, the configuration and operation of the drive signal selection circuit 200, which generates the drive signal VOUT by selecting or not selecting the signal waveform included in the drive signal COM, will be explained. Figure 9 This is a diagram showing the configuration of the drive signal selection circuit 200. (As shown) Figure 9 As shown, the drive signal selection circuit 200 includes a selection control circuit 210 and a plurality of selection circuits 230, the same number as the plurality of piezoelectric elements 60. It should be noted that in the following description, the printhead 22 is described as having p piezoelectric elements 60. That is, the drive signal selection circuit 200 has p selection circuits 230.

[0153] The selection control circuit 210 receives a clock signal SCK, a printed data signal SI, a latch signal LAT, and a change signal CH. Furthermore, within the selection control circuit 210, groups of shift registers (S / R) 212, latch circuits 214, and decoders 216 are respectively provided for 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.

[0154] The print data signal SI is input to the selection control circuit 210 synchronously with the clock signal SCK. Furthermore, the print data signal SI and each of the p piezoelectric elements 60 serially includes 2-bit print data [SIH, SIL] for selecting any one of "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 stored in p shift registers 212 corresponding to the p p piezoelectric elements 60. Specifically, the p shift registers 212 corresponding to the p piezoelectric elements 60 are cascaded together, and the serially input print data signal SI is sequentially transmitted to the subsequent shift register 212 according to the clock signal SCK. Furthermore, the clock signal SCK stops when the print data [SIH, SIL] is stored in the corresponding shift register 212. Thus, the print data [SIH, SIL] included in the print data signal SI is stored in the corresponding shift register 212. It should be noted that... Figure 9 In order to distinguish the p shift registers 212, they are sequentially labeled as level 1, level 2, ..., level p, starting from the upstream side of the input printed data signal SI.

[0155] Each of the p latch circuits 214 latches the printed data [SIH, SIL] held in its corresponding shift register 212 simultaneously when the latch signal LAT rises. Furthermore, the printed data [SIH, SIL] latched by the latch circuits 214 is input to the corresponding decoder 216. Figure 10This diagram illustrates an example of the decoded content in decoder 216. Decoder 216 outputs selection signals S at logic levels specified by the input printed data [SIH,SIL] during periods t1, t2, and t3, respectively. For example, when printed data [SIH,SIL] = [1,0] is input to decoder 216, decoder 216 outputs the logic level of selection signal S as H, L, and L levels during periods t1, t2, and t3.

[0156] The selection signal S output by the decoder 216 is input to the selection circuit 230. The selection circuit 230 is configured 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 p p piezoelectric elements 60. Figure 11 This is a diagram showing the configuration of the selection circuit 230. (As shown) Figure 11 As shown, the selection circuit 230 includes an inverter 232 and a transmission gate 234, which are NOT circuits.

[0157] The selection signal S is input to the positive control terminal (not marked with a circle) of transmission gate 234, and after its logic level is inverted by inverter 232, it is also input to the negative control terminal (marked with a circle) of transmission gate 234. Additionally, a drive signal COM is supplied to the input terminal of transmission gate 234. Furthermore, when the selection signal S is input at a high level, transmission gate 234 sets the input terminal to conduct between the input and output terminals; when the selection signal S is input at a low level, it sets the input terminal to de-conduct between the input and output terminals. That is, when the logic level of the selection signal S is high, transmission 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 low, it does not output the signal waveform included in the drive signal COM from its output terminal. Furthermore, the drive signal selection circuit 200 outputs the signal output to the output terminal of transmission gate 234 of the selection circuit 230 as the drive signal VOUT.

[0158] Here, using Figure 12 The operation of the drive signal selection circuit 200 is explained. Figure 12 This diagram illustrates 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. Furthermore, the print data signal SI is sequentially transmitted in p shift registers 212 corresponding to p p piezoelectric elements 60, synchronized with the clock signal SCK. Then, when the input of the clock signal SCK stops, the print data [SIH, SIL] corresponding to each of the p piezoelectric elements 60 is held in the shift registers 212. It should be noted that the print data signal SI is input in the order corresponding to the p-th, ..., 2-th, and 1-th stages of the shift registers 212.

[0159] Additionally, when the latch signal LAT rises, the latch circuit 214 simultaneously latches the printed data [SIH, SIL] held in the shift register 212. It should be noted that... Figure 12 The LT1, LT2, ..., LTp shown represent the printed data [SIH, SIL] latched by the latch circuit 214 corresponding to the shift registers 212 of level 1, level 2, ..., level p.

[0160] Decoder 216, based on the size of the dots specified by the latched print data [SIH, SIL], respectively, during periods t1, t2, and t3, respectively... Figure 12 The output select signal S is shown to be at a logic level. Additionally, the selection circuit 230 generates a drive signal VOUT by selecting or not selecting the signal waveform included in the drive signal COM, based on the logic level of the select signal S output by the decoder 216.

[0161] Specifically, when printed data [SIH,SIL] = [1,1] is input to decoder 216, decoder 216 sets the logic level of selection signal S to H, H, L levels during periods t1, t2, and t3. Therefore, selection circuit 230 selects trapezoidal waveform Adp during period t1, trapezoidal waveform Bdp during period t2, and does not select trapezoidal waveform Cdp during period t3. As a result, drive signal selection circuit 200 outputs drive signal VOUT corresponding to "large point LD".

[0162] 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. In addition, the moderate and small amounts of ink ejected fall onto and bind to the medium P, thereby forming a "large dot LD" on the medium P.

[0163] Furthermore, when printed data [SIH,SIL] = [1,0] is input to decoder 216, decoder 216 sets the logic level of selection signal S to H, L, L levels during periods t1, t2, and t3. Consequently, selection circuit 230 selects trapezoidal waveform Adp during period t1, does not select trapezoidal waveform Bdp during period t2, and does not select trapezoidal waveform Cdp during period t3. As a result, drive signal selection circuit 200 outputs drive signal VOUT corresponding to the "midpoint MD".

[0164] When the drive signal VOUT corresponding to the "midpoint 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. In addition, the moderate amount of ink ejected falls onto the medium P, thereby forming the "midpoint MD" on the medium P.

[0165] Furthermore, when printed data [SIH,SIL] = [0,1] is input to decoder 216, decoder 216 sets the logic level of selection signal S to L, H, and L levels during periods t1, t2, and t3. Consequently, selection circuit 230 does not select trapezoidal waveform Adp during period t1, selects trapezoidal waveform Bdp during period t2, and does not select trapezoidal waveform Cdp during period t3. As a result, drive signal selection circuit 200 outputs drive signal VOUT corresponding to "small dot SD".

[0166] When the drive signal VOUT corresponding to the "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. In addition, the small amount of ink ejected falls onto the medium P, thereby forming the "small dot SD" on the medium P.

[0167] Furthermore, when printed data [SIH,SIL] = [0,0] is input to decoder 216, decoder 216 sets the logic level of selection signal S to L, L, H levels during periods t1, t2, and t3. Consequently, selection circuit 230 does not select trapezoidal waveform Adp during period t1, does not select trapezoidal waveform Bdp during period t2, and selects trapezoidal waveform Cdp during period t3. As a result, drive signal selection circuit 200 outputs drive signal VOUT corresponding to "Do not record ND".

[0168] When the drive signal VOUT corresponding to "No ND Recording" 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, it becomes "No ND Recording" where no dot is formed on the medium P. At this time, the drive signal VOUT including the trapezoidal waveform Cdp is input to the corresponding piezoelectric element 60. Therefore, micro-vibration is performed. As a result, the possibility of increased ink viscosity near the opening of the corresponding nozzle 321 is reduced.

[0169] As described above, the drive signal selection circuit 200 generates a drive signal VOUT by selecting or not selecting the signal waveform of the drive signal COM output by the drive circuit 50, and outputs it to the corresponding piezoelectric element 60. Therefore, the drive signal VOUT includes any one of the trapezoidal waveforms Adp, Bdp, and Cdp included in the drive signal COM output by the drive circuit 50. In this way, the printhead 22 that ejects ink based on the drive signal VOUT can also be regarded as ejecting ink based on the drive signal COM.

[0170] Functional structure and operation of temperature information output circuit

[0171] Next, the functional structure and operation of the temperature information output circuit 26 will be explained. Figure 13 This diagram illustrates an example of the functional configuration of the temperature information output circuit 26. The temperature information output circuit 26 acquires head temperature signals TC1 to TCn, which respectively include head temperature information tc1 to tcn input from printheads 22-1 to 22-n, and a unit temperature signal TH, which includes unit temperature information th input from the temperature detection circuit 28. It then generates a temperature information signal TI representing the temperature of the printhead 22 corresponding to the temperature acquisition request signal TD input from the control circuit 100. Furthermore, the temperature information output circuit 26 outputs the generated temperature information signal TI to the control circuit 100.

[0172] like Figure 13 As shown, the temperature information output circuit 26 includes a control circuit 500, amplifier circuits 510-1 to 510-n and 520, a multiplexer 530, an AD conversion circuit 540 and 550, a DA conversion circuit 560, and a storage circuit 570.

[0173] Amplifier circuits 510-1 to 510-n are configured for printheads 22-1 to 22-n. The printhead temperature signals TC1 to TCn and the reference potential signal Vref output by the corresponding printheads 22-1 to 22-n are input to amplifier circuits 510-1 to 510-n, respectively. Furthermore, amplifier circuits 510-1 to 510-n amplify the corresponding printhead temperature signals TC1 to TCn using the voltage value of the reference potential signal Vref as a reference potential, thereby outputting amplified printhead temperature signals ATC1 to ATCn.

[0174] Specifically, the printhead temperature signal TC1 and the reference potential signal Vref output by the printhead 22-1 are input to amplifier circuit 510-1. Amplifier circuit 510-1 outputs an amplified printhead temperature signal ATC1, which is the result of amplifying the difference between the voltage value of the input printhead temperature signal TC1 and the voltage value of the reference potential signal Vref. Additionally, the printhead temperature signal TCj and the reference potential signal Vref output by the printhead 22-j are input to amplifier circuit 510-j (j being any one of 1 to n). Amplifier circuit 510-j outputs an amplified printhead temperature signal ATCj, which is the result of amplifying the difference between the voltage value of the input printhead temperature signal TCj and the voltage value of the reference potential signal Vref. Here, amplifier circuits 510-1 to 510-n all have the same configuration, and unless otherwise specified in the following description, they are sometimes referred to as amplifier circuit 510. In this case, the head temperature signal TC, which is the head temperature signal TC1 to TCn, and the reference potential signal Vref are input to the amplifier circuit 510, and the head temperature amplification signal ATC, which is the head temperature amplification signal ATC1 to ATCn, is output for explanation.

[0175] The head temperature amplification signals ATC1 to ATCn output by amplifier circuits 510-1 to 510-n are input to multiplexer 530. Additionally, a selection signal Sel output by control circuit 500 is input to multiplexer 530. Multiplexer 530 selects any one of the head temperature amplification signals ATC1 to ATCn input from amplifier circuits 510-1 to 510-n according to the input selection signal Sel, and outputs it as the selected temperature signal STC.

[0176] The AD conversion circuit 540 receives the selected temperature signal STC output by the multiplexer 530 and the enable signal EN1 output by the control circuit 500. The AD conversion circuit 540 converts the selected temperature signal STC input during the active period of the enable signal EN1 into a digital signal and outputs it to the control circuit 500. That is, the AD conversion circuit 540 generates a digital signal and outputs it to the control circuit 500. This digital signal corresponds to the voltage value amplified by the amplifier circuit 510 of the voltage values ​​of the head temperature signals TC1 to TCn input to the temperature information output circuit 26, specifically the voltage value of the head temperature information tc included in the head temperature signal TC selected by the multiplexer 530 during the active period of the enable signal EN1. It is also a digital signal corresponding to the voltage value of the head temperature signal TC selected by the multiplexer 530 during the active period of the enable signal EN1, and corresponding to the temperature of the printhead 22. In the following description, the digital signal output by the AD conversion circuit 540 is referred to as the digital temperature information dtc.

[0177] The unit temperature signal TH is input to the amplifier circuit 520. Furthermore, the amplifier circuit 520 amplifies the input unit temperature signal TH to output the amplified unit temperature signal ATH.

[0178] The AD conversion circuit 550 receives the amplified temperature signal ATH output by the amplifier circuit 520 and the enable signal EN2 output by the control circuit 500. The AD conversion circuit 550 converts the amplified temperature signal ATH input during the active period of the enable signal EN2 into a digital signal and outputs it to the control circuit 500. That is, the AD conversion circuit 550 generates a digital signal and outputs it to the control circuit 500. This digital signal corresponds to the voltage value obtained by amplifying the voltage value of the unit temperature information th included in the unit temperature signal TH input during the active period of the enable signal EN2 by the amplifier circuit 520, including the voltage value corresponding to the temperature of the head unit 20 during the active period of the enable signal EN2. In the following description, the digital signal output by the AD conversion circuit 550 is sometimes referred to as the digital temperature information dth.

[0179] The digital reference potential signal dvref, output by the control circuit 500, is input to the DA conversion circuit 560. The DA conversion circuit 560 generates a reference potential signal Vref by converting the digital reference potential signal dvref into an analog signal. Furthermore, the DA conversion circuit 560 outputs the generated reference potential signal Vref to the amplifier circuits 510-1 to 510-n. That is, the voltage value of the reference potential signal Vref input to the amplifier circuits 510-1 to 510-n is controlled by the control circuit 500 and the DA conversion circuit 560.

[0180] The control circuit 500 includes a request parsing unit 502, a temperature information output unit 504, and a memory control unit 506. A temperature acquisition request signal TD is input to the control circuit 500. Furthermore, the control circuit 500 generates a selection signal Sel, enable signals EN1 and EN2, and a digital reference potential signal dvref corresponding to the input temperature acquisition request signal TD, and controls various configurations included in the temperature information output circuit 26. Additionally, the selection signal Sel and digital temperature information dtc corresponding to the enable signal EN1 are input to the control circuit 500. Based on the input digital temperature information dtc, the control circuit 500 generates a temperature information signal TI and outputs it from the temperature information output circuit 26.

[0181] Specifically, a temperature acquisition request signal TD is input to the request parsing unit 502. The request parsing unit 502 parses the input temperature acquisition request signal TD. In addition, the request parsing unit 502 outputs the digital reference potential signal dvref, the selection signal Sel, and the enable signals EN1 and EN2 corresponding to the parsing result to the corresponding configuration.

[0182] Digital temperature information dtc is input to the temperature information output unit 504. Based on the input digital temperature information dtc, the temperature information output unit 504 generates a temperature information signal TI corresponding to the temperature of the printheads 22-1 to 22-n, and outputs it to the control circuit 100. It should be noted that, in addition to digital temperature information dtc, digital temperature information dth can also be input to the temperature information output unit 504. In this case, the temperature information output unit 504 can also output a temperature information signal TI corrected based on the input digital temperature information dtc and digital temperature information dth.

[0183] The memory control unit 506 generates a memory control signal MA for accessing the memory circuit 570 and outputs it to the memory circuit 570. It also acquires a memory read signal MR output by the memory circuit 570 based on the memory control signal MA. For example, the memory control unit 506 generates a memory control signal MA for reading the voltage value of a reference potential signal Vref corresponding to the parsing result of the request parsing unit 502 from the memory circuit 570 and outputs it to the memory circuit 570. Thus, the memory read signal MR, which includes information about the voltage value read from the memory circuit 570, is input to the memory control unit 506. Additionally, the control circuit 500 generates a digital reference potential signal dvref corresponding to the voltage value read from the memory circuit 570 and outputs it to the DA conversion circuit 560.

[0184] Here, any one of the control circuit 500, amplifier circuits 510-1 to 510-n, 520, multiplexer 530, AD conversion circuit 540, 550, DA conversion circuit 560 and storage circuit 570 included in the temperature information output circuit 26 can also be configured as one or more integrated circuits.

[0185] Next, an example of the configuration of the amplifier circuit 510 in the temperature information output circuit 26 will be described. Figure 14 This is a diagram illustrating a specific example of the configuration of amplifier circuit 510. For example... Figure 14 As shown, the amplifier circuit 510 includes resistors 511 to 514 and operational amplifier 515.

[0186] An arbitrary voltage Vdd is input to the high-voltage side input terminal of operational amplifier 515, while a ground potential GND is supplied to the low-voltage side input terminal. That is, operational amplifier 515 operates based on the potential difference between voltage Vdd and ground potential GND.

[0187] The positive input terminal of operational amplifier 515 is electrically connected to one end of resistor 511 and one end of resistor 512, and the negative input terminal of operational amplifier 515 is electrically connected to one end of resistor 513 and one end of resistor 514. Additionally, a head temperature signal TC is input to the other end of resistor 511, a ground potential GND is supplied to the other end of resistor 512, a reference potential signal Vref is supplied to the other end of resistor 513, and the other end of resistor 514 is electrically connected to the output terminal of operational amplifier 515.

[0188] The amplifier circuit 510 configured as described above constitutes a so-called differential amplifier circuit. This differential amplifier circuit generates and outputs a head temperature amplified signal ATC by amplifying the signal corresponding to the difference between the voltage value of the head temperature signal TC and the voltage value of the reference potential signal Vref with an amplification rate specified by resistors 511 to 514.

[0189] Figure 15 This is a diagram illustrating an example of the relationship between the voltage value of the head temperature signal TC and the voltage value of the head temperature amplification signal ATC when an ideal head temperature signal TC is input to the amplifier circuit 510.

[0190] exist Figure 15 In this circuit, when the temperature of the printhead 22 or the liquid ejection device 1 is any temperature below the minimum temperature specified based on product specifications, the voltage value of the printhead temperature signal TC input to the amplifier circuit 510 is plotted as voltage Vtmin. When the temperature of the printhead 22 or the liquid ejection device 1 is any temperature above the maximum temperature specified based on product specifications, the voltage value of the printhead temperature signal TC input to the amplifier circuit 510 is plotted as voltage Vtmax. That is, voltage Vtmin corresponds to the voltage value of the printhead temperature information tc output by the temperature detection circuit 24 when the temperature of the printhead 22 or the liquid ejection device 1 is any temperature below the minimum temperature specified based on product specifications, and voltage Vtmax corresponds to the voltage value of the printhead temperature information tc output by the temperature detection circuit 24 when the temperature of the printhead 22 or the liquid ejection device 1 is any temperature above the maximum temperature specified based on product specifications.

[0191] In addition, Figure 15In the diagram, the voltage value of the head temperature signal TC at any given time is illustrated as voltage Vt[q], and the voltage value of the amplified head temperature signal ATC output by the amplifier circuit 510 when voltage Vt[q] is input to the amplifier circuit 510 is illustrated as voltage Va[q]. That is, voltage Vt[q] corresponds to the voltage value of the head temperature information tc acquired by the arbitrary timing temperature detection circuit 24, and voltage Va[q] corresponds to the voltage value after amplifying the head temperature information tc acquired by the arbitrary timing temperature detection circuit 24. It should be noted that in the following description, unless a specific timing is specified, the voltage value of the head temperature signal TC is sometimes referred to as voltage Vt, and the voltage value of the amplified head temperature signal ATC output by the amplifier circuit 510 when voltage Vt is input to the amplifier circuit 510 is referred to as voltage Va.

[0192] like Figure 15 As shown, the output voltage of amplifier circuit 510 has a linear relationship with the input head temperature signal TC, which is a head temperature amplification signal ATC. At this time, when the voltage value of reference potential signal Vref is set to voltage Vref, and the resistance values ​​of resistors 511 to 514 are set to resistance values ​​r511 to r514 respectively, the voltage Vt[q] input to amplifier circuit 510 and the voltage Va[q] output by amplifier circuit 510 are related as shown in equation (1).

[0193] [Mathematical Expression 1]

[0194]

[0195] In this case, the ratio of the resistance value of resistor 511 to the resistance value of resistor 512 is the same as the ratio of the resistance value of resistor 513 to the resistance value of resistor 514. Preferably, the resistance values ​​of resistors 511 to 514 are set such that the resistance values ​​of resistor 511 and resistor 513 are equal, and the resistance values ​​of resistor 512 and resistor 514 are equal. Thus, the above equation (1) can be expressed as shown in the following equation (2).

[0196] [Mathematical Expression 2]

[0197]

[0198] Here, "equal resistance values" is not limited to the actual measured resistance values ​​being the same, but also includes the range considered equal after taking into account deviations in resistance values. That is, "resistance values ​​of resistor 511 and resistor 513 are equal" means that the rated resistance values ​​of resistor 511 and resistor 513 are the same, and "resistance values ​​of resistor 512 and resistor 514 are equal" means that the rated resistance values ​​of resistor 512 and resistor 514 are the same.

[0199] As described above, the amplifier circuit 510 of this embodiment outputs a voltage Va[q] obtained by multiplying the voltage difference between voltage Vt[q] and voltage vref by an amplification factor defined by the ratio of the resistance values ​​of resistors 513 and 514. In other words, the amplifier circuit 510 of this embodiment constitutes a differential amplifier circuit that amplifies the difference between the reference potential signal Vref and the head temperature signal TC.

[0200] In addition, such as Figure 15 As shown, in this embodiment, the amplifier circuit 510 sets the resistance values ​​of resistors 511 to 514 to a predetermined amplification factor such that the voltage value of the amplified printhead temperature signal ATC is approximately 0V when the voltage value of the printhead temperature signal TC is Vtmin, and the voltage value of the amplified printhead temperature signal ATC is approximately Vdd when the voltage value of the printhead temperature signal TC is Vtmax. That is, the amplification factor of the amplifier circuit 510, i.e., the resistance values ​​of resistors 511 to 514, is set such that the dynamic range of the amplifier circuit 510 is from the ground potential GND input to the low-potential side input terminal of the operational amplifier 515 to the voltage Vdd input to the high-potential side input terminal of the operational amplifier 515. As a result, the detection accuracy of the printhead temperature signal TC in the amplifier circuit 510 is improved, and the output accuracy of the amplified printhead temperature signal ATC output by the amplifier circuit 510 is improved. Consequently, the temperature detection accuracy of the printhead 22 based on the amplified printhead temperature signal ATC output by the amplifier circuit 510 can be improved.

[0201] Here, any temperature where the voltage value of the printhead temperature signal TC is Vtmin refers to, for example, the lowest design temperature at which the printhead 22 or the liquid ejection device 1 can operate without failure. Any temperature where the voltage value of the printhead temperature signal TC is Vtmax refers to, for example, the highest design temperature at which the printhead 22 or the liquid ejection device 1 can operate without failure. It should be noted that any temperature where the voltage value of the printhead temperature signal TC is Vtmin, and any temperature where the voltage value of the printhead temperature signal TC is Vtmax, is not limited to the temperatures mentioned above, and can also be any temperature corresponding to the intended use or operating environment of the liquid ejection device 1.

[0202] Furthermore, setting the dynamic range of amplifier circuit 510 to be from the ground potential GND of the low-potential input terminal of operational amplifier 515 to the voltage Vdd of the high-potential input terminal of operational amplifier 515 means that, after considering the deviation of the resistance values ​​of resistors 511 to 514, the bias voltage of operational amplifier 515, etc., the dynamic range of amplifier circuit 510 is set to be from the ground potential GND of the low-potential input terminal of operational amplifier 515 to the voltage Vdd of the high-potential input terminal of operational amplifier 515. That is, the resistance values ​​of resistors 511 to 514 are not limited to being set to be from the ground potential GND of the low-potential input terminal of operational amplifier 515 to the voltage Vdd of the high-potential input terminal of operational amplifier 515, as long as the low-potential voltage value of the dynamic range of amplifier circuit 510 is as close as possible to the ground potential GND, and the high-potential voltage value of the dynamic range of amplifier circuit 510 is as close as possible to the voltage Vdd.

[0203] However, in the case where a temperature detection circuit 24 including a resistive wiring 401 is provided inside the printhead 22 as shown in this embodiment, since the resistive wiring 401 included in the temperature detection circuit 24 is formed into a thin wiring pattern, the resistance value of the resistive wiring 401 may deviate significantly due to manufacturing deviations, etc. That is, there is a possibility that the voltage value of the printhead temperature information tc output by the printhead 22 may deviate significantly.

[0204] The deviation in the voltage value of the head temperature signal TC, which includes head temperature information tc, is directly related to the deviation in the voltage value of the head temperature amplified signal ATC output by the amplifier circuit 510. In particular, in situations such as... Figure 15 While ensuring a large dynamic range for the amplifier circuit 510, the voltage value of the output head temperature amplified signal ATC is limited by the voltage Vdd or the ground potential GND due to the deviation in the voltage value of the head temperature signal TC, which includes head temperature information tc. As a result, the reliability of the head temperature amplified signal ATC output by the amplifier circuit 510 may be reduced.

[0205] To address this problem, for example, by adjusting the resistance values ​​of resistors 511 to 514 included in amplifier circuit 510, the dynamic range of amplifier circuit 510 can be reduced, thereby reducing the possibility that the voltage value of the head temperature amplified signal ATC will be limited due to deviations in the voltage value of the head temperature signal TC, which includes head temperature information tc. However, in this case, because the dynamic range of amplifier circuit 510 is reduced, the acquisition accuracy of the head temperature signal TC in amplifier circuit 510 is reduced, and the reliability of the head temperature amplified signal ATC output by amplifier circuit 510 is reduced.

[0206] That is, when a temperature detection circuit 24, which includes resistive wiring 401 and is used inside the printhead 22 to detect the temperature of the printhead 22, a new problem arises where the reliability of the printhead temperature amplification signal ATC output by the amplifier circuit 510 may be reduced.

[0207] To address this issue, in the liquid ejection device 1 and head unit 20 of this embodiment, the voltage value deviation of the head temperature information tc, which may be caused by the deviation of the resistance value of the resistive wiring 401 included in the temperature detection circuit 24, is corrected by adjusting the voltage value of the reference potential signal Vref. This reduces the possibility that the voltage value of the head temperature amplification signal ATC may be limited while ensuring a large dynamic range of the amplifier circuit 510. As a result, even when a configuration using a temperature detection circuit 24 including resistive wiring 401 internally configured in the printhead 22 to detect the temperature of the printhead 22 is employed, the possibility of reduced reliability of the head temperature amplification signal ATC output by the amplifier circuit 510 is reduced. Consequently, the accuracy of the temperature information of the printhead 22 included in the temperature information signal TI output by the temperature information output circuit 26 is improved. In other words, the accuracy of temperature acquisition of the printhead 22 is improved in configurations where the temperature detection circuit 24 is internally provided in the printhead 22.

[0208] That is, in the liquid ejection device 1 and the head unit 20 of this embodiment, the temperature information output circuit 26 has an amplifier circuit 510 that amplifies the difference between the reference potential signal Vref and the head temperature signal TC, a temperature information output unit 504 that outputs the output of the amplifier circuit 510 as a temperature information signal TI, a control circuit 500 that outputs the reference potential signal Vref corresponding to the voltage value of the head temperature signal TC to the amplifier circuit 510, and a DA conversion circuit 560. This improves the reliability of the head temperature amplified signal ATC output by the amplifier circuit 510 and the accuracy of the temperature of the print head 22 included in the temperature information signal TI output by the temperature information output circuit 26.

[0209] Here, a specific example of the method for adjusting the voltage value of the reference potential signal Vref input to the amplifier circuit 510 will be explained. Figure 16 This is a diagram illustrating an example of a method for adjusting the voltage value of the reference potential signal Vref.

[0210] First, when adjusting the voltage value of the reference potential signal Vref, the temperature information output circuit 26 calculates the voltage value of the head temperature amplified signal ATC output by the amplifier circuit 510 when an ideal voltage value is input to the amplifier circuit 510, based on the resistance values ​​r511 to r514 of the resistors 511 to 514 in the amplifier circuit 510 and the above equation (2). Furthermore, the temperature information output circuit 26 stores the calculated ideal voltage Var in the storage circuit 570 corresponding to the voltage value of the head temperature signal TC. This ideal voltage Var can be calculated based on the known resistance values ​​r511 to r514 of the resistors 511 to 514 and the known design information of the temperature detection circuit 24 including the resistor wiring 401. Therefore, the ideal voltage Var corresponding to the voltage value of the head temperature signal TC can, for example, be stored in the storage circuit 570 during the manufacturing stage of the liquid ejection device 1.

[0211] By inputting a temperature acquisition request signal TD from the control circuit 100, the temperature information output circuit 26 begins adjusting the voltage vref corresponding to the amplifier circuits 510-1 to 510-n respectively (step S100). This temperature acquisition request signal TD requests adjustment of the voltage value of the reference potential signal Vref input to the amplifier circuits 510-1 to 510-n respectively corresponding to the printheads 22-1 to 22-n, i.e., voltage vref. Here, in this embodiment, the temperature information output circuit 26 calculates the voltage value of the reference potential signal Vref corresponding to the amplifier circuits 510-1 to 510-n respectively. Therefore, in the following description, the voltage value of the reference potential signal Vref corresponding to the amplifier circuit 510-1 will be referred to as voltage vref1, and the voltage value of the reference potential signal Vref corresponding to the amplifier circuit 510-n will be referred to as voltage vrefn.

[0212] The temperature information output circuit 26 initializes variable j to j = 1 by acquiring the temperature request signal TD, which is the input request signal to adjust the voltage value of the reference potential signal Vref (step S110). Then, since variable j is "1", the control circuit 500 reads the voltage value information of voltage vref1 from the storage circuit 570 (step S120). In addition, the control circuit 500 generates a digital reference potential signal dvref corresponding to the read voltage value of voltage vref1 and outputs it to the DA conversion circuit 560. That is, the control circuit 500 outputs the digital reference potential signal dvref corresponding to the read voltage value of voltage vref1 (step S130). As a result, the DA conversion circuit 560 outputs the reference potential signal Vref corresponding to the amplifier circuit 510-1, that is, the reference potential signal Vref with a voltage value of voltage vref1, to the amplifier circuit 510-1.

[0213] Additionally, the temperature information output circuit 26 generates a selection signal Sel for selecting the head temperature amplified signal ATC1 amplified by the amplifier circuit 510-1, and outputs it to the multiplexer 530. Thus, the multiplexer 530 selects the head temperature amplified signal ATC1 as the head temperature amplified signal ATCj (step S140) and outputs it as the selected temperature signal STC.

[0214] Then, the control circuit 500 included in the temperature information output circuit 26 outputs an enable signal EN2 to enable the analog-to-digital conversion in the AD conversion circuit 550. As a result, the AD conversion circuit 550 outputs digital temperature information dth, which is obtained by amplifying the voltage value of the unit temperature information th included in the unit temperature signal TH output by the temperature detection circuit 28 through the amplifier circuit 520. The control circuit 500 acquires the digital temperature information dth output by the AD conversion circuit 550 (step S150).

[0215] The control circuit 500 calculates the voltage value of the ideal printhead temperature signal TC, which corresponds to the temperature specified by the acquired digital temperature information dth. Here, the temperature specified by the digital temperature information dth is the temperature of the printhead units 20, including printheads 22-1 to 22-n, which is approximately the same as the ambient temperature of printheads 22-1 to 22-n when printheads 22-1 to 22-n are not driven. In other words, the control circuit 500 estimates the temperature of printhead 22-1 based on the temperature specified by the digital temperature information dth, and calculates the voltage value of the ideal printhead temperature signal TC based on the estimated temperature.

[0216] Additionally, the control circuit 500 reads the ideal voltage Var corresponding to the voltage value of the head temperature signal TC in the calculated ideal state from the storage circuit 570. That is, the control circuit 500 reads the ideal voltage Var corresponding to the temperature specified by the digital temperature information dth from the storage circuit 570 (step S160).

[0217] Then, the control circuit 500 included in the temperature information output circuit 26 outputs an enable signal EN1 to enable the analog-to-digital conversion in the AD conversion circuit 540. Consequently, the AD conversion circuit 540 outputs digital temperature information dtc to the control circuit 500. This digital temperature information dtc is obtained by converting the selected temperature signal STC output by the multiplexer 530, i.e., the selected temperature signal STC corresponding to the head temperature amplification signal ATC1, into a digital signal. That is, the control circuit 500 acquires the digital temperature information dtc output by the AD conversion circuit 540 (step S170).

[0218] The control circuit 500 compares the voltage value corresponding to the acquired digital temperature information dtc with the voltage value of the ideal voltage Var read from the storage circuit 570. Furthermore, the control circuit 500 determines whether the voltage value corresponding to the digital temperature information dtc is within a specified range based on the voltage value of the ideal voltage Var.

[0219] Specifically, the control circuit 500 compares the voltage value specified by the acquired digital temperature information dtc with the value of the ideal voltage Var read from the storage circuit 570 minus a predetermined value α1 (step S180). Furthermore, if the voltage value specified by the acquired digital temperature information dtc is less than or equal to the value of the ideal voltage Var read from the storage circuit 570 minus the predetermined value α1 (step S180 is "Yes"), the control circuit 500 calculates the voltage value of the reference potential signal Vref corresponding to the amplifier circuit 510-1, i.e., the voltage vref1 minus a predetermined value β, as the new voltage vref1 (step S185).

[0220] On the other hand, if the voltage value specified by the acquired digital temperature information dtc is greater than the value of the ideal voltage Var read from the storage circuit 570 minus the specified value α1 (step S180 is "No"), the control circuit 500 compares the voltage value specified by the acquired digital temperature information dtc with the value of the ideal voltage Var read from the storage circuit 570 plus the specified value α2 (step S190). Furthermore, if the voltage value specified by the acquired digital temperature information dtc is greater than or equal to the value of the ideal voltage Var read from the storage circuit 570 plus the specified value α2 (step S190 is "Yes"), the control circuit 500 calculates the voltage value of the reference potential signal Vref corresponding to the amplifier circuit 510-1, i.e., the voltage vref1 plus the specified value β, as the new voltage vref1 (step S195).

[0221] Additionally, in step S185 or S195, after calculating the new voltage vref1, the control circuit 500 generates and outputs a digital reference potential signal dvref corresponding to the calculated voltage vref1 (step S200). Consequently, the DA conversion circuit 560 outputs the reference potential signal Vref corresponding to the amplifier circuit 510-1, i.e., the reference potential signal Vref with a voltage value of the newly calculated voltage vref1, to the amplifier circuit 510.

[0222] Then, the control circuit 500 acquires the digital temperature information dtc output by the AD conversion circuit 540 again (step S160). That is, the control circuit 500 acquires the digital temperature information dtc after converting the selected temperature signal STC corresponding to the head temperature amplification signal ATC1 into a digital signal. The head temperature amplification signal ATC1 is obtained by amplifying the difference between the voltage value of the head temperature signal TC and the reference potential signal Vref of the newly calculated voltage vref1 by the amplification circuit 510-1. In addition, the control circuit 500 compares the voltage value specified by the acquired digital temperature information dtc with the voltage value of the ideal voltage Var read from the storage circuit 570, and adjusts the voltage value of voltage vref1 according to the comparison result. The control circuit 500 repeatedly performs the adjustment of the voltage value of voltage vref1 until the voltage value specified by the input digital temperature information dtc is within the specified range based on the voltage value of the ideal voltage Var. Specifically, the control circuit 500 repeatedly adjusts the voltage value of voltage vref1 until the voltage value specified by the acquired digital temperature information dtc is greater than the value of the ideal voltage Var read from the storage circuit 570 minus the specified value α1 (step S180 is "No"), and less than the value of the ideal voltage Var read from the storage circuit 570 plus the specified value α2 (step S190 is "No").

[0223] Furthermore, the control circuit 500 stores the voltage vref1 corresponding to the amplification circuit 510-1 in the storage circuit 570 when the voltage value specified by the acquired digital temperature information dtc is greater than the value obtained by subtracting the specified value α1 from the ideal voltage Var read from the storage circuit 570 (step S180 is "No"), and less than the value obtained by adding the specified value α2 to the ideal voltage Var read from the storage circuit 570 (step S190 is "No") (step S210). It should be noted that the execution in... Figure 16 The order of the processes performed in steps S180 and S185 shown can also be reversed compared to the order of the processes performed in steps S190 and S195.

[0224] Then, the temperature information output circuit 26 adds "1" to variable j (step S220) and determines whether the added variable j is less than or equal to the total number of printheads 22 included in the head unit 20, i.e., "n" (step S230). Furthermore, if variable j is less than or equal to the total number of printheads 22 included in the head unit 20, i.e., "n" (step S230 is "Yes"), the temperature information output circuit 26 repeatedly executes the processing steps S120 to S230. Thus, the temperature information output circuit 26 calculates the voltage values ​​of the reference potential signals Vref, i.e., voltages vref1 to vrefn, corresponding to the amplifier circuits 510-1 to 510-n respectively set for printheads 22-1 to 22-n, and stores them in the storage circuit 570. Then, if variable j exceeds the total number of printheads 22 included in the head unit 20, i.e., "n" (step S230 is "No"), the temperature information output circuit 26 ends the adjustment of the voltage value of the reference potential signal Vref.

[0225] Here, the aforementioned specified values ​​α1 and α2 are, for example, values ​​obtained by multiplying the potential difference between voltage Vdd and ground potential GND by a specified ratio, such as 1% of the potential difference. Additionally, the specified value β is any voltage value that specifies the adjustment range of the adjusted voltage vref.

[0226] Next, the acquisition of the temperature of the printhead 22 using voltages vref1 to vrefn stored in the storage circuit 570 in the temperature information output circuit 26 will be explained. Figure 17 This is a diagram illustrating an example of the temperature control operation of printhead 22. (For example...) Figure 17 As shown, by inputting a temperature acquisition request signal TD (step S510) from the control circuit 100 to the temperature information output circuit 26 to request the temperature of any one of the multiple printheads 22, the temperature information output circuit 26 starts temperature information output processing.

[0227] When a temperature acquisition request signal TD is input to the temperature information output circuit 26, requesting the temperature of any one of the multiple printheads 22, the request parsing unit 502 included in the control circuit 500 of the temperature information output circuit 26 parses the temperature acquisition request signal TD and determines the printhead 22-k (k is any one from 1 to n) among the multiple printheads 22 to acquire the temperature (step S520). Then, the temperature information output circuit 26 reads the voltage vrefk corresponding to the printhead 22-k from the storage circuit 570 and outputs a digital reference potential signal dvref corresponding to the read voltage vrefk (step S530). As a result, a reference potential signal Vref of voltage vrefk with adjusted voltage value is input to the amplifier circuit 510-k.

[0228] Additionally, the temperature information output circuit 26 generates a selection signal Sel for the selected head temperature amplification signal ATCk and outputs it to the multiplexer 530 (step S540). This head temperature amplification signal ATCk is obtained by amplifying the potential difference between the head temperature signal TC output by the printhead 22-k and the reference potential signal Vref by the amplifier circuit 510-k. Thus, the multiplexer 530 selects the head temperature amplification signal ATCk and outputs it as the selected temperature signal STC. This head temperature amplification signal ATCk is obtained by amplifying the difference between the head temperature signal TC output by the printhead 22-k and the reference potential signal Vref (with adjusted voltage vrefk) by the amplifier circuit 510-k.

[0229] Then, the control circuit 500 included in the temperature information output circuit 26 outputs an enable signal EN1 to enable the analog-to-digital conversion in the AD conversion circuit 540. As a result, the AD conversion circuit 540 converts the selected temperature signal STC, i.e., the printhead temperature amplification signal ATCk, into digital temperature information dtc and outputs it to the control circuit 500. This printhead temperature amplification signal ATCk is obtained by amplifying the difference between the printhead temperature signal TC output by the printhead 22-k and the reference potential signal Vref, which is a voltage vrefk with an adjusted voltage value, using the amplification circuit 510-k. That is, the control circuit 500 acquires the digital temperature information dtc output by the AD conversion circuit 540 (step S550).

[0230] Additionally, the temperature information output unit 504 included in the control circuit 500 outputs a temperature information signal TI corresponding to the input digital temperature information dtc, that is, a temperature information signal TI after converting the input digital temperature information dtc into a specified format (step S560). Specifically, the temperature information output unit 504 outputs the digital temperature information dtc corresponding to the head temperature information tck representing the temperature of the print head 22-k as the temperature information signal TI. Therefore, the temperature information output circuit 26 terminates the output of the temperature information signal TI.

[0231] That is, the temperature information output circuit 26 of the liquid ejection device 1 and the head unit 20 in this embodiment includes an amplification circuit 510 that amplifies the difference between the reference potential signal Vref and the head temperature signal TC, a temperature information output unit 504 that outputs a temperature information signal TI corresponding to the output of the amplification circuit 510, a DA conversion circuit 560 and a control circuit 500 that control the voltage value of the reference potential signal Vref, and a storage circuit 570 that stores voltages vref1 to vrefn corresponding to the head temperature signal TC and the ambient temperature of the print head 22. The DA conversion circuit 560 and the control circuit 500 output a reference potential signal Vref corresponding to the voltage values ​​of voltages vref1 to vrefn.

[0232] Here, using Figure 18 and Figure 19 The method for adjusting the voltage value of the aforementioned reference potential signal Vref is illustrated. Figure 18 This diagram illustrates an example of the head temperature amplified signal ATC output by amplifier circuit 510 before and after adjustment of the reference potential signal Vref. It should be noted that... Figure 18 In the diagram, the relationship between the voltage value of the head temperature signal TC and the voltage value of the head temperature amplification signal ATC when the ideal head temperature signal TC is input is plotted as a straight line A. Before adjusting the voltage value of the reference potential signal Vref, i.e., the voltage vref, the relationship between the voltage value of the input head temperature signal TC and the voltage value of the head temperature amplification signal ATC is plotted as a straight line B. During the adjustment of the voltage value of the reference potential signal Vref, i.e., the voltage vref, the relationship between the voltage value of the input head temperature signal TC and the voltage value of the head temperature amplification signal ATC is plotted as a straight line C.

[0233] like Figure 18 As shown in (a), before the voltage value of the reference potential signal Vref, i.e., voltage vref, is adjusted, when the voltage value of the head temperature signal TC is voltage Vt[q], and the voltage value of the head temperature amplified signal ATC output by the amplifier circuit 510, i.e., voltage Va[q], is smaller than the ideal voltage Var, as described above, the control circuit 500 subtracts a predetermined value β from the voltage value of the reference potential signal Vref, i.e., voltage vref1, and outputs a new voltage vref corresponding to the head temperature signal TC and the amplifier circuit 510. Therefore, when the voltage value of the head temperature signal TC is voltage Vt[q], as... Figure 18 As shown in (b), the voltage value of the head temperature amplified signal ATC output by amplifier circuit 510, i.e., voltage Va[q], increases. In other words, when the voltage value of the head temperature signal TC is voltage Vt[q], the voltage value of the head temperature amplified signal ATC output by amplifier circuit 510, i.e., voltage Va[q], is close to the ideal voltage Var.

[0234] Furthermore, the control circuit 500 repeatedly adjusts the voltage vref based on the comparison result between the voltage value of the head temperature amplified signal ATC (i.e., voltage Va[q]) and the ideal voltage Var. When the voltage value of the head temperature signal TC is voltage Vt[q], the voltage value of the head temperature amplified signal ATC (i.e., voltage Va[q]) output by the amplification circuit 510 is within a specified range relative to the ideal voltage Var, thereby achieving the desired effect. Figure 18 As shown in (c), the voltage value of the head temperature amplification signal ATC output by the amplifier circuit 510 is approximately equal to the voltage value of the head temperature amplification signal ATC output by the amplifier circuit 510 when an ideal head temperature signal TC is input to the amplifier circuit 510.

[0235] Figure 19 This is another example of the head temperature amplified signal ATC output by amplifier circuit 510 before and after adjustment of the reference potential signal Vref. It should be noted that... Figure 19 In, with Figure 18 Similarly, the relationship between the voltage value of the head temperature signal TC and the voltage value of the head temperature amplification signal ATC when the ideal head temperature signal TC is input is plotted as a straight line A. Before the voltage value of the reference potential signal Vref (i.e., voltage vref) is adjusted, the relationship between the voltage value of the input head temperature signal TC and the voltage value of the head temperature amplification signal ATC is plotted as a straight line B. During the adjustment of the voltage value of the reference potential signal Vref (i.e., voltage vref), the relationship between the voltage value of the input head temperature signal TC and the voltage value of the head temperature amplification signal ATC is plotted as a straight line C.

[0236] like Figure 19 As shown in (a), before the voltage value of the reference potential signal Vref, i.e., voltage vref, is adjusted, when the voltage value of the head temperature signal TC is voltage Vt[q], and the voltage value of the head temperature amplified signal ATC output by the amplifier circuit 510, i.e., voltage Va[q], is greater than the ideal voltage Var, as described above, the control circuit 500 adds a predetermined value β to the voltage value of the reference potential signal Vref, i.e., voltage vref1, and outputs it as a new voltage vref corresponding to the head temperature signal TC and the amplifier circuit 510. Therefore, when the voltage value of the head temperature signal TC is voltage Vt[q], as... Figure 19 As shown in (b), the voltage value of the head temperature amplified signal ATC output by amplifier circuit 510, i.e., voltage Va[q], decreases. In other words, when the voltage value of the head temperature signal TC is voltage Vt[q], the voltage value of the head temperature amplified signal ATC output by amplifier circuit 510, i.e., voltage Va[q], is close to the ideal voltage Var.

[0237] Furthermore, the control circuit 500 repeatedly adjusts the voltage vref based on the comparison result between the voltage value of the head temperature amplified signal ATC (i.e., voltage Va[q]) and the ideal voltage Var. When the voltage value of the head temperature signal TC is voltage Vt[q], the voltage value of the head temperature amplified signal ATC (i.e., voltage Va[q]) output by the amplification circuit 510 is within a specified range relative to the ideal voltage Var, thereby achieving the desired effect. Figure 19 As shown in (c), the voltage value of the head temperature amplification signal ATC output by the amplifier circuit 510 is approximately equal to the voltage value of the head temperature amplification signal ATC output by the amplifier circuit 510 when an ideal head temperature signal TC is input to the amplifier circuit 510.

[0238] As described above, in the liquid ejection device 1 and printhead unit 20 of this embodiment, the deviation in the voltage value of the printhead temperature information tc, which may be caused by the deviation in the resistance value of the resistive wiring 401 included in the temperature detection circuit 24, is corrected by adjusting the voltage value of the reference potential signal Vref. Therefore, even when ensuring a large dynamic range of the amplifier circuit 510, the possibility of the voltage value of the printhead temperature amplification signal ATC being limited is reduced, and consequently, the possibility of reduced reliability of the printhead temperature amplification signal ATC output by the amplifier circuit 510 is reduced. Thus, the accuracy of the temperature information of the printhead 22 included in the temperature information signal TI output by the temperature information output circuit 26 is improved.

[0239] Here, the drive signal COM is an example of a drive signal, and given that the drive signal VOUT is generated by selecting or not selecting the signal waveform included in the drive signal COM, the drive signal VOUT is also an example of a drive signal.

[0240] In addition, the temperature information output circuit 26 is an example of a temperature information output circuit, the temperature information signal TI output by the temperature information output circuit 26 is an example of a temperature information signal, the amplifier circuit 510-1 included in the temperature information output circuit 26 is an example of a first amplifier circuit, the amplifier circuit 510-2 included in the temperature information output circuit 26 is an example of a second amplifier circuit, the temperature information output section 504 included in the temperature information output circuit 26 is an example of an output control circuit, the control circuit 500 and the DA conversion circuit 560 included in the temperature information output circuit 26 are an example of a reference voltage control circuit, and the storage circuit 570 included in the temperature information output circuit 26 is an example of a storage section.

[0241] In addition, head temperature information tc1 is an example of first temperature information, head temperature information tc2 is an example of second temperature information, head temperature signal TC1 including head temperature information tc1 is an example of first temperature signal, head temperature signal TC2 including head temperature information tc2 is an example of second temperature signal, voltage vref1 is an example of first reference voltage value, voltage vref2 is an example of second reference voltage value, reference potential signal Vref with voltage value vref1 is an example of first reference potential signal, and reference potential signal Vref with voltage value vref2 is an example of second reference potential signal.

[0242] Furthermore, printhead 22-1 is an example of a first printhead, electrode 360 ​​included in printhead 22-1 is an example of a first electrode, electrode 380 included in printhead 22-1 is an example of a second electrode, piezoelectric element 370 included in printhead 22-1 is an example of a first piezoelectric element, piezoelectric element 60 included in printhead 22-1 is an example of a first piezoelectric element, vibrating plate 350 included in printhead 22-1 is an example of a first vibrating plate, pressure chamber 312 included in printhead 22-1 is an example of a first pressure chamber, pressure chamber substrate 310 included in printhead 22-1 is an example of a first pressure chamber substrate, nozzle 321 included in printhead 22-1 is an example of a first nozzle, and resistor wiring 401 and temperature detection circuit 24 included in printhead 22-1 are an example of a first temperature detection unit.

[0243] Furthermore, printhead 22-2 is an example of a second printhead; electrode 360 ​​included in printhead 22-2 is an example of a third electrode; electrode 380 included in printhead 22-2 is an example of a fourth electrode; piezoelectric element 370 included in printhead 22-2 is an example of a second piezoelectric element; piezoelectric element 60 included in printhead 22-2 is an example of a second piezoelectric element; vibrating plate 350 included in printhead 22-2 is an example of a second vibrating plate; pressure chamber 312 included in printhead 22-2 is an example of a second pressure chamber; pressure chamber substrate 310 included in printhead 22-2 is an example of a second pressure chamber substrate; nozzle 321 included in printhead 22-2 is an example of a second nozzle; and resistor wiring 401 and temperature detection circuit 24 included in printhead 22-2 are examples of a second temperature detection unit.

[0244] Additionally, the direction along the Z-axis is an example of both the first and second stacking directions; the +Z side along the Z-axis is an example of one side of both the first and second stacking directions; and the -Z side along the Z-axis is an example of the other side of both the first and second stacking directions.

[0245] 3. Effects

[0246] As described above, the print head 22 of the head unit 20 of the liquid ejection device 1 in this embodiment includes: a piezoelectric element 60, comprising an electrode 360, an electrode 380, and a piezoelectric body 370. In the stacking direction of the electrodes 360, 380, and 370, i.e., along the Z-axis, the piezoelectric body 370 is located between the electrodes 360 and 380 and is driven by a drive signal VOUT based on a drive signal COM; and a vibrating plate 350, located on one side of the piezoelectric element 60 in the stacking direction, which, through... The piezoelectric element 60 is deformed by driving; the pressure chamber substrate 310, located on one side of the vibrating plate 350 in the stacking direction, is provided with a pressure chamber 312 whose volume changes according to the deformation of the vibrating plate 350; the nozzle 321 ejects ink according to the change in volume of the pressure chamber 312; and the temperature detection circuit 24 includes a resistor wiring 401 located on the other side of the vibrating plate 350 in the stacking direction, which detects the head temperature information tc corresponding to the temperature of the pressure chamber 312 and outputs it as a head temperature signal TC. That is, in the printhead 22 of this embodiment, the temperature detection circuit 24, which detects the temperature of the ink stored in the pressure chamber 312, is located near the pressure chamber 312. As a result, the temperature detection circuit 24 improves the detection accuracy of the temperature of the ink stored in the pressure chamber 312.

[0247] Furthermore, the temperature information output circuit 26 of the head unit 20 of the liquid ejection device 1 in this embodiment includes an amplifier circuit 510 that amplifies the difference between the reference potential signal Vref and the head temperature signal TC, a temperature information output unit 504 that outputs a temperature information signal TI corresponding to the output of the amplifier circuit 510, a control circuit 500 that controls the voltage value of the reference potential signal Vref, and a DA conversion circuit 560. Therefore, the voltage range of the head temperature amplified signal ATC output by the amplifier circuit 510 can be adjusted without changing the amplification rate of the amplifier circuit 510. As a result, the detection accuracy of the head temperature signal TC by the temperature detection circuit 24 is improved, and the output accuracy of the head temperature amplified signal ATC output by the amplifier circuit 510 is improved. Consequently, the temperature detection accuracy of the printhead 22 based on the head temperature amplified signal ATC output by the amplifier circuit 510 can be improved.

[0248] 4. Variations

[0249] In the above embodiment, the ideal voltage Var was calculated based on the temperature of the head unit 20 detected by the temperature detection circuit 28, and the calculated ideal voltage Var was used to adjust the voltage value of the reference potential signal Vref, i.e., voltage vref. However, when adjusting the voltage value of the reference potential signal Vref, i.e., voltage vref, the liquid ejection device 1 or the head unit 20 can also be placed in an environment with a constant temperature, the ideal voltage Var can be calculated based on that temperature, and the calculated ideal voltage Var can be used to adjust the voltage value of the reference potential signal Vref, i.e., voltage vref. Even with this configuration, the same effect as the above embodiment can be achieved.

[0250] The embodiments and variations have been described above, but the present invention is not limited to these embodiments and can be implemented in various ways without departing from its spirit. For example, the above embodiments can also be appropriately combined.

[0251] This invention includes configurations that are substantially the same as those described in the embodiments (e.g., configurations with the same function, method, and result, or configurations with the same purpose and effect). Additionally, this invention includes configurations that replace non-essential parts of the configurations described in the embodiments. Furthermore, this invention includes configurations that achieve the same effect as those described in the embodiments or that can achieve the same purpose. Additionally, this invention includes configurations that incorporate known techniques into the configurations described in the embodiments.

[0252] The following content is derived from the above implementation method.

[0253] One type of head unit is a head unit that ejects liquid by receiving a drive signal corrected based on temperature information signals, and has the following features:

[0254] A first printhead receives the drive signal and ejects liquid; and

[0255] The temperature information output circuit outputs a temperature information signal representing the temperature of the first printhead.

[0256] The first print head has:

[0257] The first piezoelectric element includes a first electrode, a second electrode, and a first piezoelectric body. In a first stacking direction in which the first electrode, the second electrode, and the first piezoelectric body are stacked, the first piezoelectric body is located between the first electrode and the second electrode and receives the driving signal to be driven.

[0258] The first vibrating plate is located on one side of the first piezoelectric element in the first stacking direction and is deformed by the drive of the first piezoelectric element;

[0259] The first pressure chamber substrate, located on one side of the first vibrating plate in the first stacking direction, is provided with a first pressure chamber whose volume varies according to the deformation of the first vibrating plate.

[0260] A first nozzle ejects liquid according to changes in the volume of the first pressure chamber; and

[0261] The first temperature detection unit, located on the opposite side of the first vibrating plate in the first stacking direction, detects first temperature information corresponding to the temperature of the first pressure chamber and outputs it as a first temperature signal.

[0262] The temperature information output circuit has the following features:

[0263] The first amplifier circuit amplifies the difference between the first reference potential signal and the first temperature signal;

[0264] The output control circuit outputs the temperature information signal corresponding to the output of the first amplifier circuit; and

[0265] The reference voltage control circuit controls the voltage value of the first reference potential signal.

[0266] According to this head unit, by controlling the voltage value of the first reference potential signal amplified by the first amplifier circuit through the reference voltage control circuit, even if the voltage value of the first temperature signal output by the first temperature detection unit, i.e., the voltage value of the first temperature information, deviates, the first amplifier circuit can still acquire the first temperature signal while ensuring the dynamic range. Therefore, the acquisition accuracy of the first temperature signal in the first amplifier circuit is improved. As a result, the output accuracy of the first amplifier circuit is improved, and the accuracy of the temperature information signal output by the temperature information output circuit based on the output of the first amplifier circuit is improved. That is, the temperature acquisition accuracy of the printhead in the temperature information output circuit is improved.

[0267] In one embodiment of the aforementioned header unit,

[0268] The temperature information output circuit has a storage unit.

[0269] The storage unit stores a first reference voltage value corresponding to the first temperature information and the ambient temperature of the first printhead.

[0270] The reference voltage control circuit can also output the first reference potential signal with a voltage value corresponding to the first reference voltage value.

[0271] According to this printhead unit, a first reference voltage value is calculated based on the voltage value of the first temperature signal output by the first temperature detection unit (i.e., the voltage value of the first temperature information) and the ambient temperature of the printhead. The calculated first reference voltage value is stored in a storage unit. The reference voltage control circuit controls the voltage value of the first reference potential signal based on the first reference voltage value. That is, the reference voltage control circuit outputs a first reference potential signal with a voltage value calculated based on the ambient temperature of the printhead. Therefore, the accuracy of the voltage value of the first reference potential signal output by the reference voltage control circuit is further improved.

[0272] In one embodiment of the aforementioned header unit,

[0273] It has a second printhead that receives the drive signal and ejects liquid.

[0274] The second print head has:

[0275] The second piezoelectric element includes a third electrode, a fourth electrode, and a second piezoelectric body. In a second stacking direction in which the third electrode, the fourth electrode, and the second piezoelectric body are stacked, the second piezoelectric body is located between the third electrode and the fourth electrode and receives the driving signal to be driven.

[0276] The second vibrating plate is located on one side of the second piezoelectric element in the second stacking direction and is deformed by the drive of the second piezoelectric element;

[0277] The second pressure chamber substrate, located on one side of the second vibrating plate in the second stacking direction, is provided with a second pressure chamber whose volume varies according to the deformation of the second vibrating plate;

[0278] The second nozzle ejects liquid according to the change in volume of the second pressure chamber; and

[0279] The second temperature detection unit, located on the opposite side of the second vibrating plate in the second stacking direction, detects second temperature information corresponding to the temperature of the second pressure chamber and outputs it as a second temperature signal.

[0280] The temperature information output circuit has a second amplification circuit that amplifies the difference between the second reference potential signal and the second temperature signal.

[0281] The reference voltage control circuit outputs a second reference potential signal, which corresponds to the voltage value of the second temperature signal, to the second amplifier circuit.

[0282] The output control circuit can also output the temperature information signal corresponding to at least one of the outputs of the first amplifier circuit and the second amplifier circuit.

[0283] Even when the head unit has a second amplification circuit for acquiring a second temperature signal in addition to the first amplification circuit for acquiring the first temperature signal, according to this head unit, by controlling the voltage value of the second reference potential signal amplified by the second amplification circuit through the reference voltage control circuit, the second amplification circuit can acquire the second temperature signal while ensuring the dynamic range even if the voltage value of the second temperature signal output by the second temperature detection unit, i.e., the voltage value of the second temperature information, deviates. Therefore, the acquisition accuracy of the second temperature signal in the second amplification circuit is improved. As a result, the output accuracy of the second amplification circuit is also improved, and the accuracy of the temperature information signal output by the temperature information output circuit based on the output of the second amplification circuit is also improved. That is, even when the head unit has multiple amplification circuits and multiple amplification circuits acquire corresponding temperature signals, the temperature acquisition accuracy of the printhead in the temperature information output circuit is improved.

[0284] In one embodiment of the aforementioned header unit,

[0285] Equipped with a storage unit,

[0286] The storage unit stores a first reference voltage value corresponding to the first temperature information and the ambient temperature of the first printhead, and a second reference voltage value corresponding to the second temperature information and the ambient temperature of the second printhead.

[0287] The reference voltage control circuit can also output a first reference potential signal with a voltage value corresponding to the first reference voltage value, and a second reference potential signal with a voltage value corresponding to the second reference voltage value.

[0288] According to this printhead unit, a first reference voltage value is calculated based on the voltage value of the first temperature signal output by the first temperature detection unit (i.e., the voltage value of the first temperature information) and the ambient temperature of the printhead. A second reference voltage value is calculated based on the voltage value of the second temperature signal output by the second temperature detection unit (i.e., the voltage value of the second temperature information) and the ambient temperature of the printhead. The calculated first and second reference voltage values ​​are stored in the storage unit. Furthermore, the reference voltage control circuit controls the voltage value of the first reference potential signal based on the first reference voltage value and controls the voltage value of the second reference potential signal based on the second reference voltage value. That is, the reference voltage control circuit outputs a first reference potential signal and a second reference potential signal with voltage values ​​calculated based on the ambient temperature of the printhead. Therefore, the accuracy of the voltage values ​​of the first and second reference potential signals output by the reference voltage control circuit is further improved.

[0289] In one embodiment of the aforementioned header unit,

[0290] The first temperature detection unit includes a wiring pattern stacked on the surface of the other side of the first vibrating plate.

[0291] The wiring pattern may also contain platinum.

[0292] According to the head unit, the first temperature detection unit includes a wiring pattern containing platinum, which has excellent linearity with respect to temperature. By stacking the wiring pattern on the first vibrating plate, the first temperature detection unit can be positioned near the first pressure chamber, thereby further improving the detection accuracy of the first temperature information corresponding to the temperature of the first pressure chamber.

[0293] One method of liquid ejection device includes:

[0294] The drive signal output circuit outputs a drive signal corrected based on temperature information; and

[0295] The head unit receives the drive signal and ejects liquid.

[0296] The head unit has:

[0297] A first printhead receives the drive signal and ejects liquid; and

[0298] The temperature information output circuit outputs a temperature information signal representing the temperature of the first printhead.

[0299] The first print head includes:

[0300] The first piezoelectric element includes a first electrode, a second electrode, and a first piezoelectric body. In a first stacking direction in which the first electrode, the second electrode, and the first piezoelectric body are stacked, the first piezoelectric body is located between the first electrode and the second electrode and receives the driving signal to be driven.

[0301] The first vibrating plate is located on one side of the first piezoelectric element in the first stacking direction and is deformed by the drive of the first piezoelectric element;

[0302] The first pressure chamber substrate, located on one side of the first vibrating plate in the first stacking direction, is provided with a first pressure chamber whose volume varies according to the deformation of the first vibrating plate.

[0303] A first nozzle ejects liquid according to changes in the volume of the first pressure chamber; and

[0304] The first temperature detection unit, located on the opposite side of the first vibrating plate in the first stacking direction, detects first temperature information corresponding to the temperature of the first pressure chamber and outputs it as a first temperature signal.

[0305] The temperature information output circuit includes:

[0306] The first amplifier circuit amplifies the difference between the first reference potential signal and the first temperature signal;

[0307] The output control circuit outputs the output of the first amplifier circuit as the temperature information signal; and

[0308] The reference voltage control circuit controls the voltage value of the first reference potential signal.

[0309] According to this liquid ejection device, by controlling the voltage value of the first reference potential signal amplified by the first amplification circuit of the head unit through the reference voltage control circuit, even if the voltage value of the first temperature signal output by the first temperature detection unit, i.e., the voltage value of the first temperature information, deviates, the first amplification circuit can still acquire the first temperature signal while ensuring the dynamic range. Therefore, the acquisition accuracy of the first temperature signal in the first amplification circuit is improved. As a result, the output accuracy of the first amplification circuit is improved, and the accuracy of the temperature information signal output by the temperature information output circuit based on the output of the first amplification circuit is improved. That is, the temperature acquisition accuracy of the printhead in the temperature information output circuit is improved.

[0310] In one embodiment of the aforementioned liquid ejection device,

[0311] The temperature information output circuit has a storage unit.

[0312] The storage unit stores a first reference voltage value corresponding to the first temperature information and the ambient temperature of the first printhead.

[0313] The reference voltage control circuit can also output the first reference potential signal with a voltage value corresponding to the first reference voltage value.

[0314] According to this liquid ejection device, a first reference voltage value is calculated based on the voltage value of the first temperature signal output by the first temperature detection unit of the printhead unit (i.e., the voltage value of the first temperature information) and the ambient temperature of the printhead. The calculated first reference voltage value is stored in a storage unit. The reference voltage control circuit controls the voltage value of the first reference potential signal based on the first reference voltage value. That is, the reference voltage control circuit outputs a first reference potential signal with a voltage value calculated based on the ambient temperature of the printhead. Therefore, the accuracy of the voltage value of the first reference potential signal output by the reference voltage control circuit is further improved.

[0315] In one embodiment of the aforementioned liquid ejection device,

[0316] The head unit has a second print head that receives the drive signal and ejects liquid.

[0317] The second print head has:

[0318] The second piezoelectric element includes a third electrode, a fourth electrode, and a second piezoelectric body. In a second stacking direction in which the third electrode, the fourth electrode, and the second piezoelectric body are stacked, the second piezoelectric body is located between the third electrode and the fourth electrode and receives the driving signal to be driven.

[0319] The second vibrating plate is located on one side of the second piezoelectric element in the second stacking direction and is deformed by the drive of the second piezoelectric element;

[0320] The second pressure chamber substrate, located on one side of the second vibrating plate in the second stacking direction, is provided with a second pressure chamber whose volume varies according to the deformation of the second vibrating plate;

[0321] The second nozzle ejects liquid according to the change in volume of the second pressure chamber; and

[0322] The second temperature detection unit, located on the opposite side of the second vibrating plate in the second stacking direction, detects second temperature information corresponding to the temperature of the second pressure chamber and outputs it as a second temperature signal.

[0323] The temperature information output circuit has a second amplification circuit that amplifies the difference between the second reference potential signal and the second temperature signal.

[0324] The reference voltage control circuit outputs a second reference potential signal, which corresponds to the voltage value of the second temperature signal, to the second amplifier circuit.

[0325] The output control circuit can also output the temperature information signal corresponding to at least one of the outputs of the first amplifier circuit and the second amplifier circuit.

[0326] Even when the head unit has a second amplification circuit for acquiring a second temperature signal in addition to the first amplification circuit for acquiring the first temperature signal, according to this liquid ejection device, in the head unit, the voltage value of the second reference potential signal amplified by the second amplification circuit is controlled by the reference voltage control circuit. Therefore, even if the voltage value of the second temperature signal output by the second temperature detection unit, i.e., the voltage value of the second temperature information, deviates, the second amplification circuit can still acquire the second temperature signal while ensuring its dynamic range. This improves the acquisition accuracy of the second temperature signal in the second amplification circuit. Consequently, the output accuracy of the second amplification circuit is also improved, and the accuracy of the temperature information signal output by the temperature information output circuit based on the output of the second amplification circuit is also improved. In other words, even when the head unit has multiple amplification circuits, and multiple amplification circuits acquire corresponding temperature signals, the temperature acquisition accuracy of the printhead in the temperature information output circuit is improved.

[0327] In one embodiment of the aforementioned liquid ejection device

[0328] Equipped with a storage unit,

[0329] The storage unit stores a first reference voltage value corresponding to the first temperature information and the ambient temperature of the first printhead, and a second reference voltage value corresponding to the second temperature information and the ambient temperature of the second printhead.

[0330] The reference voltage control circuit can also output a first reference potential signal with a voltage value corresponding to the first reference voltage value, and a second reference potential signal with a voltage value corresponding to the second reference voltage value.

[0331] According to this liquid ejection device, in the printhead unit, a first reference voltage value is calculated based on the voltage value of the first temperature signal output by the first temperature detection unit (i.e., the voltage value of the first temperature information) and the ambient temperature of the printhead. A second reference voltage value is calculated based on the voltage value of the second temperature signal output by the second temperature detection unit (i.e., the voltage value of the second temperature information) and the ambient temperature of the printhead. The calculated first and second reference voltage values ​​are stored in the storage unit. Furthermore, the reference voltage control circuit controls the voltage value of the first reference potential signal based on the first reference voltage value and controls the voltage value of the second reference potential signal based on the second reference voltage value. That is, the reference voltage control circuit outputs a first reference potential signal and a second reference potential signal with voltage values ​​calculated based on the ambient temperature of the printhead. Therefore, the accuracy of the voltage values ​​of the first and second reference potential signals output by the reference voltage control circuit is further improved.

[0332] In one embodiment of the aforementioned liquid ejection device

[0333] The first temperature detection unit includes a wiring pattern stacked on the surface of the other side of the first vibrating plate.

[0334] The wiring pattern may also contain platinum.

[0335] According to the liquid ejection device, the first temperature detection unit includes a wiring pattern containing platinum, which has excellent linearity with respect to temperature. By stacking the wiring pattern on the first vibrating plate, the first temperature detection unit can be positioned near the first pressure chamber, thereby further improving the detection accuracy of the first temperature information corresponding to the temperature of the first pressure chamber.

Claims

1. A head unit, characterized in that, It ejects liquid by receiving a drive signal corrected based on temperature information signal, and has the following characteristics: A first printhead receives the drive signal and ejects liquid; and The temperature information output circuit outputs a temperature information signal representing the temperature of the first printhead. The first print head has: The first piezoelectric element includes a first electrode, a second electrode, and a first piezoelectric body. In a first stacking direction in which the first electrode, the second electrode, and the first piezoelectric body are stacked, the first piezoelectric body is located between the first electrode and the second electrode and receives the driving signal to be driven. The first vibrating plate is located on one side of the first piezoelectric element in the first stacking direction and is deformed by the drive of the first piezoelectric element; The first pressure chamber substrate, located on one side of the first vibrating plate in the first stacking direction, is provided with a first pressure chamber whose volume varies according to the deformation of the first vibrating plate. The first nozzle ejects liquid according to the change in volume of the first pressure chamber; as well as The first temperature detection unit, located on the opposite side of the first vibrating plate in the first stacking direction, detects first temperature information corresponding to the temperature of the first pressure chamber and outputs it as a first temperature signal. The temperature information output circuit has the following features: The first amplifier circuit amplifies the difference between the first reference potential signal and the first temperature signal; The output control circuit outputs the temperature information signal corresponding to the output of the first amplifier circuit. as well as The reference voltage control circuit controls the voltage value of the first reference potential signal.

2. The head unit according to claim 1, characterized in that, The temperature information output circuit has a storage unit. The storage unit stores a first reference voltage value corresponding to the first temperature information and the ambient temperature of the first printhead. The reference voltage control circuit outputs a first reference potential signal with a voltage value corresponding to the first reference voltage value.

3. The head unit according to claim 1, characterized in that, The head unit includes a second printhead that receives the drive signal and ejects liquid. The second print head has: The second piezoelectric element includes a third electrode, a fourth electrode, and a second piezoelectric body. In a second stacking direction in which the third electrode, the fourth electrode, and the second piezoelectric body are stacked, the second piezoelectric body is located between the third electrode and the fourth electrode and receives the driving signal to be driven. The second vibrating plate is located on one side of the second piezoelectric element in the second stacking direction and is deformed by the drive of the second piezoelectric element; The second pressure chamber substrate, located on one side of the second vibrating plate in the second stacking direction, is provided with a second pressure chamber whose volume varies according to the deformation of the second vibrating plate; The second nozzle ejects liquid according to the change in volume of the second pressure chamber; as well as The second temperature detection unit, located on the opposite side of the second vibrating plate in the second stacking direction, detects second temperature information corresponding to the temperature of the second pressure chamber and outputs it as a second temperature signal. The temperature information output circuit has a second amplification circuit that amplifies the difference between the second reference potential signal and the second temperature signal. The reference voltage control circuit outputs a second reference potential signal, which corresponds to the voltage value of the second temperature signal, to the second amplifier circuit. The output control circuit outputs a temperature information signal corresponding to at least one of the outputs of the first amplifier circuit and the second amplifier circuit.

4. The head unit according to claim 3, characterized in that, The head unit includes a storage unit. The storage unit stores a first reference voltage value corresponding to the first temperature information and the ambient temperature of the first printhead, and a second reference voltage value corresponding to the second temperature information and the ambient temperature of the second printhead. The reference voltage control circuit outputs a first reference potential signal with a voltage value corresponding to the first reference voltage value, and a second reference potential signal with a voltage value corresponding to the second reference voltage value.

5. The head unit according to any one of claims 1 to 4, characterized in that, The first temperature detection unit includes a wiring pattern stacked on the surface of the other side of the first vibrating plate. The wiring pattern contains platinum.

6. A liquid ejection device, characterized in that, have: The drive signal output circuit outputs a drive signal corrected based on temperature information; and The head unit receives the drive signal and ejects liquid. The head unit has: The first print head receives the drive signal and ejects liquid; as well as The temperature information output circuit outputs a temperature information signal representing the temperature of the first printhead. The first print head includes: The first piezoelectric element includes a first electrode, a second electrode, and a first piezoelectric body. In a first stacking direction in which the first electrode, the second electrode, and the first piezoelectric body are stacked, the first piezoelectric body is located between the first electrode and the second electrode and receives the driving signal to be driven. The first vibrating plate is located on one side of the first piezoelectric element in the first stacking direction and is deformed by the drive of the first piezoelectric element; The first pressure chamber substrate, located on one side of the first vibrating plate in the first stacking direction, is provided with a first pressure chamber whose volume varies according to the deformation of the first vibrating plate. A first nozzle ejects liquid according to changes in the volume of the first pressure chamber; and The first temperature detection unit, located on the opposite side of the first vibrating plate in the first stacking direction, detects first temperature information corresponding to the temperature of the first pressure chamber and outputs it as a first temperature signal. The temperature information output circuit includes: The first amplifier circuit amplifies the difference between the first reference potential signal and the first temperature signal; The output control circuit outputs the output of the first amplifier circuit as the temperature information signal; and The reference voltage control circuit controls the voltage value of the first reference potential signal.

7. The liquid ejection device according to claim 6, characterized in that, The temperature information output circuit has a storage unit. The storage unit stores a first reference voltage value corresponding to the first temperature information and the ambient temperature of the first printhead. The reference voltage control circuit outputs a first reference potential signal with a voltage value corresponding to the first reference voltage value.

8. The liquid ejection device according to claim 6, characterized in that, The head unit has a second print head that receives the drive signal and ejects liquid. The second print head has: The second piezoelectric element includes a third electrode, a fourth electrode, and a second piezoelectric body. In a second stacking direction in which the third electrode, the fourth electrode, and the second piezoelectric body are stacked, the second piezoelectric body is located between the third electrode and the fourth electrode and receives the driving signal to be driven. The second vibrating plate is located on one side of the second piezoelectric element in the second stacking direction and is deformed by the drive of the second piezoelectric element; The second pressure chamber substrate, located on one side of the second vibrating plate in the second stacking direction, is provided with a second pressure chamber whose volume varies according to the deformation of the second vibrating plate; The second nozzle ejects liquid according to the change in volume of the second pressure chamber; as well as The second temperature detection unit, located on the opposite side of the second vibrating plate in the second stacking direction, detects second temperature information corresponding to the temperature of the second pressure chamber and outputs it as a second temperature signal. The temperature information output circuit has a second amplification circuit that amplifies the difference between the second reference potential signal and the second temperature signal. The reference voltage control circuit outputs a second reference potential signal, which corresponds to the voltage value of the second temperature signal, to the second amplifier circuit. The output control circuit outputs a temperature information signal corresponding to at least one of the outputs of the first amplifier circuit and the second amplifier circuit.

9. The liquid ejection device according to claim 8, characterized in that, The liquid ejection device includes a storage section. The storage unit stores a first reference voltage value corresponding to the first temperature information and the ambient temperature of the first printhead, and a second reference voltage value corresponding to the second temperature information and the ambient temperature of the second printhead. The reference voltage control circuit outputs a first reference potential signal with a voltage value corresponding to the first reference voltage value, and a second reference potential signal with a voltage value corresponding to the second reference voltage value.

10. The liquid ejection device according to any one of claims 6 to 9, characterized in that, The first temperature detection unit includes a wiring pattern stacked on the surface of the other side of the first vibrating plate. The wiring pattern contains platinum.

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