Head unit

Abstract

To provide a head unit capable of detecting abnormality of a plurality of print heads.SOLUTION: A head unit includes: a plurality of temperature detection circuits which include a first temperature detection circuit for detecting the presence / absence of temperature abnormality of a first drive control circuit for controlling the drive of a first driver element to which liquid is discharged from a first discharge part, and a second temperature detection circuit for detecting the presence / absence of temperature abnormality of a second drive control circuit for controlling the drive of a second driver element to which liquid is discharged from a second discharge part; an integrated information output circuit for outputting a first temperature abnormality information signal according to a plurality of detection results detected by the plurality of temperature detection circuits; an individual information output circuit for outputting a second temperature abnormality information signal according to one selected detection result from the plurality of detection results according to a section signal; a temperature information output circuit for outputting a first temperature abnormality information signal, a second temperature abnormality information signal and a temperature abnormality information signal according to the selection signal; and one temperature information output terminal for outputting a temperature information signal based on the temperature abnormality information signal.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to a head unit. [Background technology]

[0002] In order to ensure quality and safety, many print heads that eject ink in liquid ejection devices are configured to detect whether an abnormality such as temperature has occurred in the print head and output the detection result to the outside of the print head. For example, Patent Document 1 discloses a technology for detecting whether an abnormal temperature has occurred in a semiconductor element that operates a drive element in the print head. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-090501 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, liquid ejection devices have been widely used in commercial and industrial fields. In order to improve productivity, the number of nozzles ejecting liquid in such liquid ejection devices has been increasing, resulting in a rapid increase in the number of printheads included in the liquid ejection devices. When the technology described in Patent Document 1 is applied to such liquid ejection devices to detect the presence or absence of abnormalities, such as temperature abnormalities, in each of the multiple printheads, the number of signal lines transmitting the information on the presence or absence of the abnormalities increases. However, when the technology described in Patent Document 1 is used to integrate the abnormality information output by each of the multiple printheads and transmit it using a single signal, it becomes difficult to identify the printhead in which the abnormality has occurred.

[0005] That is, in terms of detecting abnormalities in a plurality of print heads in a head unit having a plurality of print heads, the technology described in Patent Document 1 alone is not sufficient, and there is room for improvement. [Means for solving the problem]

[0006] One aspect of the head unit according to the present invention is a plurality of ejection units including a first ejection unit that includes a first drive element and ejects liquid by driving the first drive element, and a second ejection unit that includes a second drive element and ejects liquid by driving the second drive element; a plurality of drive control circuits including a first drive control circuit that controls driving of the first drive element and a second drive control circuit that controls driving of the second drive element; a plurality of temperature detection circuits including a first temperature detection circuit that detects whether or not there is a temperature abnormality in the first drive control circuit and a second temperature detection circuit that detects whether or not there is a temperature abnormality in the second drive control circuit; an integrated information output circuit that outputs a first temperature abnormality information signal according to the plurality of detection results detected by the plurality of temperature detection circuits; an individual information output circuit that selects one of the plurality of detection results in response to a selection signal and outputs a second temperature abnormality information signal corresponding to the selected detection result; a temperature information output circuit that outputs the first temperature abnormality information signal, the second temperature abnormality information signal, and a temperature abnormality information signal in accordance with the selection signal; one temperature information output terminal for outputting a temperature information signal based on the temperature abnormality information signal; It has. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating a schematic configuration of a liquid ejection device. [Figure 2] FIG. 2 is a diagram illustrating a functional configuration of the liquid ejection device. [Figure 3] FIG. 2 is a diagram showing a schematic configuration of a discharge unit. [Figure 4] 10 is a diagram showing an example of a signal waveform of a drive signal COM. FIG. [Figure 5] FIG. 2 is a diagram illustrating a configuration of a drive signal selection circuit. [Figure 6] FIG. 10 is a diagram showing an example of the decoded content in the decoder. [Figure 7] FIG. 2 is a diagram illustrating a configuration of a selection circuit. [Figure 8] 10A and 10B are diagrams for explaining the operation of a drive signal selection circuit. [Figure 9] FIG. 2 is a diagram illustrating an example of the configuration of a temperature abnormality detection circuit. [Figure 10] FIG. 10 is a diagram illustrating an example of the configuration of an acquired information selection circuit. [Figure 11] FIG. 10 is a diagram illustrating an example of an information selection signal. [Figure 12] FIG. 10 is a diagram showing an example of a method for determining whether or not there is a temperature abnormality in the drive signal selection circuit 200 included in each of the print heads 22-1 to 22-6. [Figure 13] FIG. 10 is a diagram illustrating an example of the configuration of an acquired information selection circuit according to the second embodiment. [Figure 14] FIG. 10 is a diagram illustrating an example of the configuration of a temperature abnormality detection circuit according to a second embodiment. [Figure 15] FIG. 11 is a diagram illustrating an example of the configuration of an acquired information selection circuit according to a third embodiment. [Figure 16] FIG. 13 is a diagram illustrating an example of the configuration of an acquired information selection circuit according to a fourth embodiment. [Figure 17] 10 is a diagram for explaining the relationship between a temperature abnormality information signal CS output by a temperature information output circuit according to the fourth embodiment and an information selection signal SEL. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] Preferred embodiments of the present invention will be described below with reference to the drawings. The drawings used are for the convenience of explanation. Note that the embodiments described below do not unduly limit the content of the present invention as defined in the claims. Furthermore, not all of the configurations described below are necessarily essential components of the present invention.

[0009] 1. First embodiment 1.1 Structure of the liquid ejection device FIG. 1 is a diagram showing a schematic configuration of a liquid ejection device 1. The liquid ejection device 1 of the first embodiment is a serial printing inkjet printer in which a carriage 21 mounted with a head unit 20 that ejects ink, as an example of a liquid, reciprocates along a scanning axis, ejecting ink onto a medium P transported along a transport direction, thereby forming a desired image on the medium P. Note that the liquid ejection device 1 is not limited to a serial printing inkjet printer, and may also be a line printing inkjet printer. The medium P used in such a liquid ejection device 1 can be any printing target, such as printing paper, resin film, or fabric.

[0010] As shown in FIG. 1, the liquid ejection device 1 includes an ink container 2, a control unit 10, a head unit 20, a moving unit 30, and a transport unit 40.

[0011] The ink container 2 stores multiple types of ink to be ejected onto the medium P. Colors of ink stored in the ink container 2 include black, cyan, magenta, yellow, red, gray, etc. The ink container 2 that stores such ink may be an ink cartridge, a bag-shaped ink pack made of flexible film, or an ink tank that can be refilled with ink.

[0012] The control unit 10 includes a processing circuit such as a CPU (Central Processing Unit) or FPGA (Field Programmable Gate Array) and a storage circuit such as a semiconductor memory, and controls each element of the liquid ejection device 1 including the head unit 20.

[0013] The head unit 20 is mounted on a carriage 21. The carriage 21 is fixed to an endless belt 32 included in a moving unit 30. In addition to the head unit 20, an ink container 2 may be mounted on the carriage 21.

[0014] A control signal Ctrl-H for controlling the head unit 20, which is output by the control unit 10, and a drive signal COM and reference voltage signal VBS for driving the head unit 20 are input to the head unit 20 mounted on the carriage 21. Ink stored in the ink container 2 is supplied to the head unit 20 via a tube (not shown). The head unit 20 then ejects the ink supplied from the ink container 2 based on the input control signal Ctrl-H, drive signal COM, and reference voltage signal VBS.

[0015] The moving unit 30 includes a carriage motor 31 and an endless belt 32. The carriage motor 31 is driven based on a control signal Ctrl-C input from the control unit 10. The endless belt 32 rotates in accordance with the drive of the carriage motor 31. This causes the carriage 21 fixed to the endless belt 32 to reciprocate along the scanning axis. In other words, the head unit 20 mounted on the carriage 21 reciprocates along the scanning axis that intersects with the transport direction in which the medium P is transported.

[0016] The transport unit 40 includes a transport motor 41 and a transport roller 42. The transport motor 41 is driven based on a control signal Ctrl-T input from the control unit 10. The transport roller 42 rotates in accordance with the driving of the transport motor 41. As the transport roller 42 rotates, the medium P is transported in the transport direction.

[0017] As described above, the liquid ejection device 1 is linked to the transport of the medium P by the transport unit 40 and the reciprocating movement of the carriage 21 by the moving unit 30, and the head unit 20 mounted on the carriage 21 ejects ink onto the medium P. As a result, the ink ejected from the head unit 20 lands at any position on the surface of the medium P. As a result, a desired image is formed on the medium P.

[0018] 1.2 Functional configuration of the liquid ejection device Next, we will explain the functional configuration of the liquid ejection device 1. Figure 2 is a diagram showing the functional configuration of the liquid ejection device 1. As shown in Figure 2, the liquid ejection device 1 includes a control unit 10, a head unit 20, a carriage motor 31, a transport motor 41, and a cable 15.

[0019] The cable 15 electrically connects the control unit 10 and the head unit 20. Such a cable 15 preferably has flexibility that allows it to follow the movement of the carriage 21, and for example, a flexible flat cable (FFC) can be used.

[0020] The control unit 10 has a drive circuit 50, a reference voltage output circuit 52, and a control circuit 100. The control circuit 100 includes, for example, a processing circuit such as a CPU or FPGA, and a storage circuit such as a semiconductor memory. An image information signal including image data and the like is input to the control circuit 100 from an external device such as a host computer that is connected to the outside of the liquid ejection device 1 so as to be able to communicate with the outside. The control circuit 100 generates various signals for controlling the liquid ejection device 1 based on the input image information signal, and outputs the signals to corresponding components.

[0021] Specifically, the control circuit 100 determines the scanning position of the head unit 20 mounted on the carriage 21 based on a signal corresponding to the scanning position of the carriage 21 input from a linear encoder (not shown) or the like. The image forming apparatus generates and outputs various signals according to the scanning position and the input image information signal.

[0022] 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 in accordance with the scanning position of the head unit 20, and outputs this signal to the carriage motor 31. This drives the carriage motor 31, controlling the movement of the head unit 20 mounted on the carriage 21 along the scanning axis and the scanning position. The control circuit 100 also generates a control signal Ctrl-T for controlling the transport of the medium P, and outputs this signal to the transport motor 41. This drives the transport motor 41, controlling the movement of the medium P along the transport direction. Note that the control signal Ctrl-C may be converted via a driver circuit (not shown) before being input to the carriage motor 31, and the control signal Ctrl-T may be converted via a driver circuit (not shown) before being input to the transport motor 41.

[0023] In addition, the control circuit 100 generates drive data signals DI1 to DI6, a change signal CH, a latch signal LAT, and a clock signal SCK as control signals Ctrl-H for controlling the head unit 20 based on an image information signal input from an external device and the scanning position of the head unit 20 input from a linear encoder not shown, and outputs them to the head unit 20.

[0024] Furthermore, the control circuit 100 outputs a basic drive signal dO, which is a digital signal, to the drive circuit 50 as a control signal Ctrl-H. The drive circuit 50 converts the input basic drive signal dO into a digital / analog signal, and then generates a drive signal COM by class D amplifying the converted analog signal, and outputs it to the head unit 20. In other words, the basic drive signal dO output by the control circuit 100 is a digital signal that defines the waveform of the drive signal COM. Note that the basic drive signal dO may be an analog signal as long as it can define the waveform of the drive signal COM output by the drive circuit 50.

[0025] The reference voltage output circuit 52 generates a reference voltage signal VBS and outputs it to the head unit 20. The reference voltage signal VBS output by the reference voltage output circuit 52 is a signal of a potential that serves as a reference for driving the piezoelectric element 60, which will be described later, and may be, for example, a constant signal at ground potential, or a DC voltage signal of a constant potential such as 5.5V or 6V.

[0026] Here, the drive circuit 50 that outputs the drive signal COM and the reference voltage output circuit 52 that outputs the reference voltage signal VBS may be provided in the head unit 20.

[0027] The head unit 20 has an acquired information selection circuit 300 and print heads 22-1 to 22-6. Each of the print heads 22-1 to 22-6 has a temperature abnormality detection circuit 400, a drive signal selection circuit 200, and multiple discharge units 600, each of which includes a piezoelectric element 60. The head unit 20 also has terminals TMcs, TMck, TMlt, TMch, and TMd1 to TMd6 to which a cable 15 is connected. The head unit 20 receives a clock signal SCK via terminal TMck, a latch signal LAT via terminal TMlt, a change signal CH via terminal TMch, drive data signals DI1 to DI6 via terminals TMd1 to TMd6, a drive signal COM via terminal TMcm, and a reference voltage signal VBS via terminal TMvb. The head unit 20 also outputs a temperature abnormality information signal CS (described later) via terminal TMcs.

[0028] The print head 22-1 receives a drive data signal DI1, a change signal CH, a latch signal LAT, and a clock signal SCK output by the control circuit 100, a drive signal COM output by the drive circuit 50, and a reference voltage signal VBS output by the reference voltage output circuit 52. do.

[0029] The clock signal SCK, latch signal LAT, change signal CH, drive data signal DI1, and drive signal COM input to the print head 22-1 are input to the drive signal selection circuit 200. The drive signal selection circuit 200 selects or deselects the signal waveform of the drive signal COM based on the input clock signal SCK, latch signal LAT, change signal CH, and drive data signal DI1, thereby generating a drive signal VOUT corresponding to each of the multiple piezoelectric elements 60. The drive signal selection circuit 200 then outputs the generated drive signal VOUT to one end of the corresponding piezoelectric element 60. A reference voltage signal VBS is commonly supplied to the other ends of the multiple piezoelectric elements 60. Each of the multiple piezoelectric elements 60 is driven by the potential difference between the drive signal VOUT supplied individually to one end and the reference voltage signal VBS supplied commonly to the other end. An amount of ink corresponding to the drive of this piezoelectric element 60 is ejected from the print head 22-1.

[0030] The temperature abnormality detection circuit 400 is located near the drive signal selection circuit 200 and detects whether a temperature abnormality has occurred in the drive signal selection circuit 200. The temperature abnormality detection circuit 400 then generates a temperature status signal XHOT1 corresponding to the temperature of the drive signal selection circuit 200 and outputs it from the print head 22-1.

[0031] Here, print heads 22-2 to 22-6 have the same configuration and perform the same operation as print head 22-1, except for the input and output signals. That is, print head 22-i (where i is 1 to 6) receives a clock signal SCK, a latch signal LAT, a change signal CH, a drive data signal DIi, a drive signal COM, and a reference voltage signal VBS. The drive signal selection circuit 200 of print head 22-i selects or deselects the signal waveform of the drive signal COM based on the input clock signal SCK, latch signal LAT, change signal CH, and drive data signal DIi, thereby generating drive signals VOUT corresponding to each of the multiple piezoelectric elements 60.

[0032] The drive signals VOUT generated by the drive signal selection circuit 200 are individually supplied to one end of the corresponding piezoelectric elements 60. A reference voltage signal VBS is commonly supplied to the other ends of the multiple piezoelectric elements 60 of the print head 22-i. This drives each of the multiple piezoelectric elements 60 of the print head 22-i, and an amount of ink corresponding to the drive of the piezoelectric element 60 is ejected from the print head 22-i.

[0033] The temperature abnormality detection circuit 400 of the print head 22-i is located near the drive signal selection circuit 200 of the print head 22-i, and detects whether a temperature abnormality has occurred in the drive signal selection circuit 200. The temperature abnormality detection circuit 400 then generates a temperature status signal XHOTi according to the temperature of the drive signal selection circuit 200, and outputs it from the print head 22-i.

[0034] In the following description, when there is no need to distinguish between print heads 22-1 to 22-6, they may be simply referred to as print head 22. In this case, the description will be given assuming that print head 22 receives a clock signal SCK, a latch signal LAT, a change signal CH, a drive data signal DI, a drive signal COM, and a reference voltage signal VBS as inputs, and outputs a temperature status signal XHOT.

[0035] The acquired information selection circuit 300 receives the temperature status signals XHOT1 to XHOT6 output by the print heads 22-1 to 22-6, the drive data signal DI1, and the clock signal SCK.

[0036] The acquired information selection circuit 300 acquires the drive data signal DI1 based on the clock signal SCK and analyzes the command included in the acquired drive data signal DI1. The acquired information selection circuit 300 then generates a temperature abnormality information signal CS according to the analysis result of the drive data signal DI1 and the temperature state signals XHOT1 to XHOT6, and outputs it from the head unit 20 via the terminal TMcs.

[0037] As described above, the drive data signal DI1 is input to the drive signal selection circuit 200 of the print head 22-1 and also to the acquired information selection circuit 300. This drive data signal DI1 includes information for controlling the ejection of ink from the print head 22-1 and information for controlling the operation of the acquired information selection circuit 300. That is, the control circuit 100 outputs a drive data signal DI1 including information for controlling the ejection of ink from the print head 22-1 and a drive data signal DI1 including information for controlling the operation of the acquired information selection circuit 300. Depending on whether the input drive data signal DI1 includes a specific code, the acquired information selection circuit 300 determines whether the drive data signal DI1 is a signal for controlling the ejection of ink from the print head 22-1 or a signal for controlling the operation of the acquired information selection circuit 300. If the acquired information selection circuit 300 determines that the input drive data signal DI1 is a signal for controlling the operation of the acquired information selection circuit 300, it executes processing according to the drive data signal DI1. This eliminates the need to provide a dedicated signal line in the cable 15 electrically connecting the control unit 10 and the head unit 20 for transmitting commands to control the operation of the acquired information selection circuit 300, thereby reducing the number of signal lines included in the cable 15.

[0038] In addition, the acquired information selection circuit 300 may determine, based on the timing at which the drive data signal DI1 is input, whether the drive data signal DI1 is a signal for controlling the ejection of ink from the print head 22-1 or a signal for controlling the operation of the acquired information selection circuit 300.

[0039] The temperature abnormality information signal CS output by the acquired information selection circuit 300 is input to the control circuit 100 via the terminal TMcs. The control circuit 100 determines whether or not there is a temperature abnormality in the head unit 20 based on the input temperature abnormality information signal CS. The head unit 20 then corrects or stops output of various signals depending on whether or not there is a temperature abnormality in the head unit 20. This improves the reliability of the liquid ejection device 1.

[0040] 1.3 Configuration of the discharge section Next, we will explain the configuration of the ejection unit 600 of the print head 22. Figure 3 is a diagram showing the schematic configuration of one of the multiple ejection units 600 of the print head 22. As shown in Figure 3, the ejection unit 600 includes a piezoelectric element 60, a vibration plate 621, a cavity 631, and a nozzle 651.

[0041] The cavity 631 is filled with ink supplied from a reservoir 641. The reservoir 641 is provided in common to the multiple ejection units 600 of the print head 22. Ink is introduced into the reservoir 641 from the ink container 2 via an ink flow path (not shown) and an ink supply port 661. In other words, the cavity 631 is filled with ink stored in the ink container 2.

[0042] 3, the vibration plate 621 is displaced by driving the piezoelectric element 60 provided on the upper surface. The internal volume of the cavity 631 filled with ink expands or contracts in accordance with the displacement of the vibration plate 621. In other words, the vibration plate 621 functions as a diaphragm that changes the internal volume of the cavity 631.

[0043] The nozzle 651 is provided in the nozzle plate 632 and is an opening that communicates with the cavity 631. When the internal volume of the cavity 631 changes, an amount of ink corresponding to the change in internal volume is ejected from the nozzle 651.

[0044] The piezoelectric element 60 has a structure in which a piezoelectric body 601 is sandwiched between a pair of electrodes 611 and 612. In the piezoelectric body 601 having such a structure, the central portions of the electrodes 611 and 612 bend up and down together with the diaphragm 621 in accordance with the potential difference of the voltages supplied by the electrodes 611 and 612. Specifically, a drive signal VOUT is supplied to one of the electrodes 611 and 612 of the piezoelectric element 60. A reference voltage signal VBS, which serves as a reference for the displacement of the piezoelectric element 60, is supplied to the other of the electrodes 611 and 612 of the piezoelectric element 60. Then, for example, when the voltage level of the drive signal VOUT increases, the central portion of the piezoelectric element 60 bends upward, and when the voltage level of the drive signal VOUT decreases, the central portion bends downward.

[0045] In the ejection section 600 configured as described above, when the piezoelectric element 60 is driven to bend upward, the center of the vibration plate 621 is displaced upward, and the internal volume of the cavity 631 is expanded. As a result, ink is drawn in from the reservoir 641. On the other hand, when the piezoelectric element 60 is driven to bend downward, the center of the vibration plate 621 is displaced downward, and the internal volume of the cavity 631 is reduced. As a result, an amount of ink corresponding to the degree of reduction is ejected from the nozzle 651. In other words, the head unit 20 has a plurality of ejection sections 600 that include the piezoelectric element 60 and eject ink when the piezoelectric element 60 is driven.

[0046] 3, the piezoelectric element 60 included in the ejection unit 600 may have any structure as long as it can eject ink from the ejection unit 600. Therefore, the piezoelectric element 60 is not limited to the bending vibration structure described above, and may have a longitudinal vibration structure. Furthermore, the piezoelectric element 60 may have a structure in which the central portion bends upward when the voltage level of the drive signal VOUT decreases, and bends downward when the voltage level of the drive signal VOUT increases.

[0047] 1.4 Functional configuration of the drive signal selection circuit Next, we will explain the configuration and operation of the drive signal selection circuit 200 of the print head 22. As described above, the drive signal selection circuit 200 of the print head 22 selects or deselects a signal waveform included in the drive signal COM based on the clock signal SCK, drive data signal DI, latch signal LAT, and change signal CH, thereby generating a drive signal VOUT and outputting it to the piezoelectric element 60 included in the corresponding ejection section 600. Such a drive signal selection circuit 200 is configured as, for example, an integrated circuit device.

[0048] Before describing the configuration and operation of the drive signal selection circuit 200, we will first describe an example of the waveform of the drive signal COM input to the drive signal selection circuit 200. Fig. 4 is a diagram showing an example of the signal waveform of the drive signal COM. As shown in Fig. 4, the drive signal COM includes a trapezoidal waveform Adp that is placed during a period td1 from when the latch signal LAT rises until when the change signal CH rises, a trapezoidal waveform Bdp that is placed during a period td2 from when the change signal CH rises until when the next change signal CH rises, and a trapezoidal waveform Cdp that is placed during a period td3 from when the change signal CH rises until when the latch signal LAT rises.

[0049] The trapezoidal waveform Adp is a signal waveform that drives the piezoelectric element 60 so that a predetermined amount of ink is ejected, and the trapezoidal waveform Bdp is a signal waveform that drives the piezoelectric element 60 so that an amount of ink smaller than the predetermined amount is ejected. The trapezoidal waveform Cdp is a signal waveform that drives the piezoelectric element 60 to such an extent that ink is not ejected, and is used to vibrate the ink near the nozzle opening corresponding to the piezoelectric element 60, thereby reducing the risk of an increase in ink viscosity near the nozzle opening. The trapezoidal waveforms Adp, Bdp, and Cdp are signal waveforms that have a common voltage Vc at their start and end times. That is, each of the trapezoidal waveforms Adp, Bdp, and Cdp starts and ends at voltage Vc.

[0050] In the following description, a predetermined amount of ink ejected when a trapezoidal waveform Adp is supplied to the piezoelectric element 60 may be referred to as a medium amount, and an amount of ink smaller than the predetermined amount ejected when a trapezoidal waveform Bdp is supplied to the piezoelectric element 60 may be referred to as a small amount. Also, when a trapezoidal waveform Cdp is supplied to the piezoelectric element 60, the operation of vibrating the ink near the nozzle opening corresponding to that piezoelectric element 60 to prevent an increase in ink viscosity may be referred to as micro-vibration. Note that the signal waveform of the drive signal COM shown in Figure 4 is an example and is not limited to this; various combinations of waveforms may be used depending on the properties of the ink being ejected, the material of the medium P on which the ink lands, etc.

[0051] The drive signal selection circuit 200 selects or deselects trapezoidal waveforms Adp, Bdp, and Cdp included in the drive signal COM during periods td1, td2, and td3, respectively, based on the clock signal SCK, the drive data signal DI, the latch signal LAT, and the change signal CH. This controls the size of the dots formed on the medium P during period tp, which is the signal waveform of the drive signal VOUT supplied to the ejection unit 600.

[0052] The configuration and operation of a drive signal selection circuit 200 that generates a drive signal VOUT by selecting or deselecting a signal waveform included in such a drive signal COM will be described below. Figure 5 is a diagram showing the configuration of the drive signal selection circuit 200. As shown in Figure 5, the drive signal selection circuit 200 has a selection control circuit 210 and a number of selection circuits 230 equal to the number of ejection units 600. In the following description, the print head 22 will be described as having m ejection units 600.

[0053] A clock signal SCK, a drive data signal DI, a latch signal LAT, and a change signal CH are input to the selection control circuit 210. Furthermore, the selection control circuit 210 is provided with a set of a shift register (S / R) 212, a latch circuit 214, and a decoder 216 corresponding to each of the m discharge units 600. That is, the drive signal selection circuit 200 includes m shift registers 212, m latch circuits 214, and m decoders 216.

[0054] The drive data signal DI is input to the selection control circuit 210 in synchronization with the clock signal SCK. The drive data signal DI also includes 2-bit drive data [DIH, DIL] for selecting one of large dots LDt, medium dots MDt, small dots SDt, and non-printing dots NDt, serially connected to each of the m discharge sections 600. The drive data [DIH, DIL] included in the drive data signal DI is held in m shift registers 212 corresponding to the m discharge sections 600. Specifically, the m shift registers 212 corresponding to the piezoelectric elements 60 are cascade-connected, and the serially input drive data signal DI is sequentially transferred to the subsequent shift register 212 in accordance with the clock signal SCK. The clock signal SCK stops when the drive data [DIH, DIL] is held in the corresponding shift register 212. As a result, the drive data [DIH, DIL] included in the drive data signal DI is held in the corresponding shift register 212. In FIG. 5, in order to distinguish the m shift registers 212, they are denoted as 1st stage, 2nd stage, . . . , mth stage in order from the upstream side to which the drive data signal DI is input.

[0055] Each of the m latch circuits 214 simultaneously latches the drive data [DIH, DIL] held in the corresponding shift register 212 at the rising edge of the latch signal LAT. The drive data [DIH, DIL] latched by the latch circuit 214 is input to the corresponding decoder 216. FIG. 6 is a diagram showing an example of the decoded content in the decoder 216. The decoder 216 outputs a waveform selection signal S of a logic level defined by the input drive data [DIH, DIL] during each of periods td1, td2, and td3. For example, when drive data [DIH, DIL]=[1, 0] is input to the decoder 216, the decoder 216 outputs the waveform selection signal S as logic levels of H, L, L during periods td1, td2, and td3.

[0056] The waveform selection signal S output by the decoder 216 is input to a selection circuit 230. A selection circuit 230 is provided corresponding to each of the m discharge sections 600. That is, the drive signal selection circuit 200 has m selection circuits 230, the same number as the m discharge sections 600. FIG. 7 is a diagram showing the configuration of the selection circuit 230. As shown in FIG. 7, the selection circuit 230 includes an inverter 232, which is a NOT circuit, and a transfer gate 234.

[0057] The waveform selection signal S is input to a positive control terminal (not marked with a circle) of the transfer gate 234, and after its logical level is inverted by the inverter 232, is also input to a negative control terminal (marked with a circle) of the transfer gate 234. The drive signal COM is also supplied to the input terminal of the transfer gate 234. When a high-level waveform selection signal S is input, the transfer gate 234 establishes conduction between its input terminal and output terminal, and when a low-level waveform selection signal S is input, the transfer gate 234 establishes non-conduction between its input terminal and output terminal. That is, when the logical level of the waveform selection signal S is high, the transfer gate 234 outputs the signal waveform included in the drive signal COM from its output terminal, and when the logical level of the waveform selection signal S is low, the transfer gate 234 does not output the signal waveform included in the drive signal COM from its output terminal. The drive signal selection circuit 200 outputs the signal output to the output terminal of the transfer gate 234 of the selection circuit 230 as the drive signal VOUT.

[0058] Here, the operation of the drive signal selection circuit 200 will be described. FIG. 8 is a diagram for explaining the operation of the drive signal selection circuit 200. The drive data signal DI is input to the selection control circuit 210 as a serial signal synchronized with the clock signal SCK. The drive data signal DI is then transferred sequentially in m shift registers 212 corresponding to m discharge units 600, synchronized with the clock signal SCK. Thereafter, when the input of the clock signal SCK stops, the shift register 212 holds the drive data [DIH, DIL] corresponding to each of the m discharge units 600. The drive data signal DI is input in the order corresponding to the mth, ..., second, and first discharge units 600 of the shift register 212.

[0059] When the latch signal LAT rises, the latch circuits 214 simultaneously latch the drive data [DIH, DIL] held in the shift registers 212. Note that LT1, LT2, ..., LTm shown in Fig. 8 indicate the drive data [DIH, DIL] latched by the latch circuits 214 corresponding to the 1st, 2nd, ..., mth stages of the shift registers 212.

[0060] 6 during each of periods td1, td2, and td3 in accordance with the dot size defined by the latched drive data [DIH, DIL]. Then, the selection circuit 230 selects or deselects a signal waveform included in the drive signal COM in accordance with the logic level of the waveform selection signal S output by the decoder 216, thereby generating the drive signal VOUT.

[0061] Specifically, when the drive data [DIH, DIL]=[1, 1] is input to the decoder 216, the decoder 216 sets the logic level of the waveform selection signal S to 0 during periods td1, td2, td3, td4, td5, td6, td7, td8, td9, td10, td11, td12, td13, td14, The drive signal selection circuit 200 outputs the drive signal VOUT corresponding to the large dot LDt.

[0062] When a drive signal VOUT corresponding to a large dot LDt is supplied to the piezoelectric element 60 included in the corresponding ejection section 600, a medium amount of ink is ejected in period td1, a small amount of ink is ejected in period td2, and no ink is ejected in period td3. The ejected medium amount of ink and the small amount of ink then land on the medium P and combine to form a large dot LDt on the medium P.

[0063] Furthermore, when drive data [DIH, DIL] = [1, 0] is input to the decoder 216, the decoder 216 sets the logic levels of the waveform selection signal S to H, L, L levels during periods td1, td2, and td3. This causes the selection circuit 230 to select the trapezoidal waveform Adp during period td1, not select the trapezoidal waveform Bdp during period td2, and not select the trapezoidal waveform Cdp during period td3. As a result, the drive signal selection circuit 200 outputs a drive signal VOUT corresponding to a medium dot MDt.

[0064] When a drive signal VOUT corresponding to a medium dot MDt is supplied to the piezoelectric element 60 included in the corresponding ejection section 600, a medium amount of ink is ejected in period td1, no ink is ejected in period td2, and no ink is ejected in period td3. Then, the ejected medium amount of ink lands on the medium P, forming a medium dot MDt on the medium P.

[0065] Furthermore, when drive data [DIH, DIL] = [0, 1] is input to the decoder 216, the decoder 216 sets the logic levels of the waveform selection signal S to L, H, L levels during periods td1, td2, and td3. As a result, the selection circuit 230 does not select the trapezoidal waveform Adp during period td1, selects the trapezoidal waveform Bdp during period td2, and does not select the trapezoidal waveform Cdp during period td3. As a result, the drive signal selection circuit 200 outputs a drive signal VOUT corresponding to a small dot SDt.

[0066] When a drive signal VOUT corresponding to a small dot SDt is supplied to the piezoelectric element 60 included in the corresponding ejection section 600, no ink is ejected during period td1, a small amount of ink is ejected during period td2, and no ink is ejected during period td3. Then, the small amount of ink that is ejected lands on the medium P, forming a small dot SDt on the medium P.

[0067] Furthermore, when drive data [DIH, DIL]=[0, 0] is input to the decoder 216, the decoder 216 sets the logic levels of the waveform selection signal S to L, L, H levels during periods td1, td2, and td3. As a result, the selection circuit 230 does not select the trapezoidal waveform Adp during period td1, does not select the trapezoidal waveform Bdp during period td2, and selects the trapezoidal waveform Cdp during period td3. As a result, the drive signal selection circuit 200 outputs a drive signal VOUT corresponding to non-recording NDt.

[0068] When a drive signal VOUT corresponding to the non-printing NDt is supplied to the piezoelectric element 60 included in the corresponding ejection section 600, no ink is ejected in period td1, no ink is ejected in period td2, and no ink is ejected in period td3. Therefore, ink is not ejected from the ejection section 600, and a non-printing NDt occurs in which no dots are formed on the medium P. At this time, a drive signal VOUT including a trapezoidal waveform Cdp is input to the corresponding piezoelectric element 60. Therefore, a micro-vibration is performed. As a result, the vicinity of the nozzle opening of the corresponding ejection section 600 This reduces the risk of the ink viscosity increasing.

[0069] As described above, in the liquid ejection device 1 of the first embodiment, the print head 22 has a piezoelectric element 60 that is driven by the supply of a drive signal COM, and ejects ink, which is an example of a liquid, by driving the piezoelectric element 60. That is, the head unit 20 has a plurality of drive signal selection circuits 200 corresponding to each of the print heads 22-1 to 22-6, and the plurality of drive signal selection circuits 200 control the driving of the piezoelectric element 60 included in the ejection section 600 of the corresponding print head 22.

[0070] 1.5 Temperature detection circuit configuration Next, a specific example of the configuration and operation of the temperature abnormality detection circuit 400 will be described. FIG. 9 is a diagram showing an example of the configuration of the temperature abnormality detection circuit 400. As shown in FIG. 9, the temperature abnormality detection circuit 400 includes diodes 420-1 to 420-k, a reference voltage generation circuit 430, a comparator 440, a transistor 460, and resistors 410 and 450. Such a temperature abnormality detection circuit 400 is configured, for example, as an integrated circuit device and is arranged near the drive signal selection circuit 200. In this case, the integrated circuit device that configures the temperature abnormality detection circuit 400 and the integrated circuit device that configures the drive signal selection circuit 200 may be the same integrated circuit device. In other words, the temperature abnormality detection circuit 400 and the drive signal selection circuit 200 may be implemented in a single integrated circuit device.

[0071] A voltage signal VDD having a constant voltage value is supplied to the temperature abnormality detection circuit 400. The voltage signal VDD supplied to the temperature abnormality detection circuit 400 may be generated based on a bandgap reference of an integrated circuit device including the temperature abnormality detection circuit 400, or may be generated by a power supply circuit (not shown) provided outside the temperature abnormality detection circuit 400.

[0072] The voltage signal VDD supplied to the temperature abnormality detection circuit 400 is input to a reference voltage generation circuit 430, one end of a resistor 410, and one end of a resistor 450. The reference voltage generation circuit 430 transforms the voltage value of the input voltage signal VDD to generate a voltage signal Vref with a constant voltage value. The voltage signal Vref generated by the reference voltage generation circuit 430 is then input to the positive input terminal of a comparator 440. The other end of the resistor 410 is electrically connected to the anode terminal of a diode 420-1. The cathode terminal of the diode 420-1 is electrically connected to the anode terminal of a diode 420-2, the cathode terminal of the diode 420-2 is electrically connected to the anode terminal of a diode 420-3, and the cathode terminal of a diode 420-j (j is any one of 1 to k-1) is electrically connected to the anode terminal of a diode 420-(j+1). That is, diodes 420-1 to 420-k are connected in series. At this time, the anode terminal of diode 420-1 provided at one end of diodes 420-1 to 420-k connected in series is electrically connected to the other end of resistor 410, and the ground potential is supplied to the cathode terminal of diode 420-k provided at the other end of diodes 420-1 to 420-k connected in series.

[0073] Then, a signal at the connection point where the other end of resistor 410 and the anode terminal of diode 420-1 are electrically connected, and whose voltage value is the sum of the forward voltages of diodes 420-1 to 420-k connected in series, is input to the negative input terminal of comparator 440 as voltage signal Vdet.

[0074] The comparator 440 operates using the potential difference between the voltage signal VDD supplied to the high-potential power supply terminal and the ground potential signal supplied to the low-potential power supply terminal as a driving source. The output terminal of the comparator 440 is electrically connected to the gate terminal of the transistor 460. The drain terminal of the transistor 460 is electrically connected to the other end of the resistor 450, and the ground potential is supplied to the source terminal of the transistor 460. The signal at the drain terminal of the transistor 460 is output from the temperature abnormality detection circuit 400 as the temperature status signal XHOT.

[0075] In temperature abnormality detection circuit 400 configured as described above, the forward voltage values ​​of diodes 420-1 to 420-k decrease when the temperature of diodes 420-1 to 420-k increases. That is, the voltage value of voltage signal Vdet changes depending on the temperature of diodes 420-1 to 420-k, that is, the temperature of drive signal selection circuit 200 located near diodes 420-1 to 420-k. Voltage signal Vdet, whose voltage value changes depending on the temperature, is input to the negative input terminal of comparator 440.

[0076] The comparator 440 compares the voltage value of the voltage signal Vref input to the + input terminal with the voltage value of the voltage signal Vdet input to the - input terminal. The comparator 440 then outputs a signal whose voltage value becomes the L level of the ground potential when the voltage value of the voltage signal Vdet is greater than the voltage value of the voltage signal Vref, and whose voltage value becomes the H level of the voltage signal VDD when the voltage value of the voltage signal Vdet is smaller than the voltage value of the voltage signal Vref.

[0077] Here, the voltage value of the voltage signal Vref output by the reference voltage generation circuit 430 is set to the voltage value of the voltage signal Vdet input to the comparator 440 when the temperature of the drive signal selection circuit 200 is at the highest temperature within the temperature range in which the drive signal selection circuit 200 can operate stably. That is, the comparator 440 outputs a signal that is at L level when the temperature of the drive signal selection circuit 200 is within the temperature range in which the drive signal selection circuit 200 can operate stably, and is at H level when the temperature of the drive signal selection circuit 200 exceeds the temperature range in which the drive signal selection circuit 200 can operate stably. Note that the voltage value of the voltage signal Vref input to the comparator 440 is not determined solely based on the temperature of the drive signal selection circuit 200, but may also be determined by comprehensively taking into account the temperatures of other components of the print head 22.

[0078] The signal output by the comparator 440 is input to the gate terminal of the transistor 460. When an H-level signal is input to the gate terminal of the transistor 460, the transistor 460 establishes conduction between the drain terminal and the source terminal. At this time, the temperature abnormality detection circuit 400 outputs an L-level temperature status signal XHOT. On the other hand, when an L-level signal is input to the gate terminal of the transistor 460, the transistor 460 establishes non-conduction between the drain terminal and the source terminal. At this time, the temperature abnormality detection circuit 400 outputs an H-level temperature status signal XHOT.

[0079] That is, the temperature abnormality detection circuit 400 outputs an L-level temperature status signal XHOT when the temperature of the drive signal selection circuit 200 is outside the temperature range in which the drive signal selection circuit 200 can operate stably, and outputs an H-level temperature status signal XHOT when the temperature of the drive signal selection circuit 200 is within the temperature range in which the drive signal selection circuit 200 can operate stably. In other words, the temperature abnormality detection circuit 400 outputs an L-level temperature status signal XHOT when the temperature of the corresponding drive signal selection circuit 200 is abnormal, and outputs an H-level temperature status signal XHOT when the temperature of the corresponding drive signal selection circuit 200 is normal.

[0080] As described above, the head unit 20 has a plurality of temperature abnormality detection circuits 400, and each of the plurality of temperature abnormality detection circuits 400 detects whether or not a temperature abnormality has occurred in the corresponding drive signal selection circuit 200.

[0081] 1.6 Configuration of the acquisition information selection circuit Next, a description will be given of the configuration and operation of the acquired information selection circuit 300. Fig. 10 is a diagram showing an example of the configuration of the acquired information selection circuit 300. As shown in Fig. 10, the acquired information selection circuit The device 300 includes an integrated information output circuit 310, an individual information output circuit 320, a temperature information output circuit 330, and an acquired information selection control circuit 340.

[0082] A clock signal SCK and a drive data signal DI1 are input to the acquired information selection control circuit 340. The acquired information selection control circuit 340 acquires the drive data signal DI1 at a timing based on the clock signal SCK and analyzes the command included in the acquired drive data signal DI1. The acquired information selection control circuit 340 then generates and outputs an information selection signal SEL according to the analysis result.

[0083] The integrated information output circuit 310 outputs a temperature abnormality information signal CS1 corresponding to the temperature status signals XHOT1 to XHOT6, which is the detection result of the presence or absence of temperature abnormalities in the multiple drive signal selection circuits 200 detected by each of the multiple temperature abnormality detection circuits 400 possessed by the head unit 20.

[0084] Specifically, the integrated information output circuit 310 includes an AND circuit 312. The AND circuit 312 receives the temperature status signals XHOT1 to XHOT6 output by the print heads 22-1 to 22-6, respectively. The AND circuit 312 then outputs a signal corresponding to the logic levels of the input temperature status signals XHOT1 to XHOT6. The signal output by the AND circuit 312 is output from the integrated information output circuit 310 as the temperature abnormality information signal CS1.

[0085] As described above, in the liquid ejection device 1 of the first embodiment, the temperature status signals XHOT1 to XHOT6 output by each of the print heads 22-1 to 22-6 are H level when the temperature of the corresponding drive signal selection circuit 200 is normal, and are L level when the temperature of the corresponding drive signal selection circuit 200 is abnormal. When these temperature status signals XHOT1 to XHOT6 are input to the AND circuit 312, the integrated information output circuit 310 outputs a temperature abnormality information signal CS1 that is H level when the temperatures of all of the drive signal selection circuits 200 included in each of the print heads 22-1 to 22-6 are normal, and is L level when an abnormality has occurred in the temperature of at least one of the drive signal selection circuits 200 included in each of the print heads 22-1 to 22-6.

[0086] That is, in the liquid ejection device 1 of the first embodiment, the temperature abnormality detection circuit 400 of each print head 22-i detects a temperature abnormality in the drive signal selection circuit 200 of each print head 22-i, and outputs a temperature status signal XHOTi that goes low if a temperature abnormality is detected in the drive signal selection circuit 200 of each print head 22-i, and goes high if a temperature abnormality in the drive signal selection circuit 200 of each print head 22-i is not detected. The integrated information output circuit 310 includes an AND circuit 312. Thus, when all of the temperature status signals XHOT1 to XHOT6 indicate normality, the integrated information output circuit 310 outputs a high-level temperature abnormality information signal CS1 that contains information indicating normality. When at least one of the temperature status signals XHOT1 to XHOT6 indicates an abnormality, the integrated information output circuit 310 outputs a low-level temperature abnormality information signal CS1 that contains information indicating abnormality.

[0087] In other words, the integrated information output circuit 310 integrates information on whether the temperatures of the drive signal selection circuits 200 included in each of the print heads 22-1 to 22-6 of the head unit 20 are normal, and outputs a temperature abnormality information signal CS1 whose logic level changes depending on whether the temperatures of all of the drive signal selection circuits 200 included in each of the print heads 22-1 to 22-6 of the head unit 20 are normal. Note that the integrated information output circuit 310 may be configured to include a circuit equivalent to an AND circuit instead of the AND circuit 312.

[0088] The individual information output circuit 320 outputs the information of the head unit 20 in response to the information selection signal SEL. The temperature abnormality detection circuits 400 respectively detect whether or not there is a temperature abnormality in the plurality of drive signal selection circuits 200, and output a temperature abnormality information signal CS2 according to the detection result by selecting one from the temperature state signals XHOT1 to XHOT6.

[0089] Specifically, the individual information output circuit 320 includes a multiplexer 322. The multiplexer 322 receives the temperature status signals XHOT1 to XHOT6 output by the print heads 22-1 to 22-6, respectively, and the information selection signal SEL output by the acquired information selection control circuit 340. The multiplexer 322 selects and outputs one of the input temperature status signals XHOT1 to XHOT6 in response to the input information selection signal SEL. The signal output by the multiplexer 322 is output from the individual information output circuit 320 as the temperature abnormality information signal CS2.

[0090] That is, the individual information output circuit 320 of the first embodiment includes a multiplexer 322 that selects one of the temperature state signals XHOT1 to XHOT6 in response to the information selection signal SEL. In such individual information output circuit 320, the multiplexer 322 includes a plurality of input terminals including an input terminal for inputting the temperature state signal XHOT1, an input terminal for inputting the temperature state signal XHOT2, an input terminal for inputting the temperature state signal XHOT3, an input terminal for inputting the temperature state signal XHOT4, an input terminal for inputting the temperature state signal XHOT5, and an input terminal for inputting the temperature state signal XHOT6, and an output terminal for outputting the temperature abnormality information signal CS2. When the temperature state signal XHOTi is selected in response to the information selection signal SEL, the multiplexer 322 electrically connects the input terminal for inputting the temperature state signal XHOTi to the output terminal for outputting the temperature abnormality information signal CS2, and electrically disconnects the other input terminals except the input terminal for inputting the temperature state signal XHOTi from the output terminal for outputting the temperature abnormality information signal CS2. As a result, the individual information output circuit 320 selects the temperature state signal XHOTi from the temperature state signals XHOT1 to XHOT6 in response to the information selection signal SEL, and outputs it as the temperature abnormality information signal CS2.

[0091] In addition, instead of the multiplexer 322, the individual information output circuit 320 may be configured to have a switch element that switches the electrical connection between the terminal to which the temperature state signal XHOT1 is input and the output terminal that outputs the temperature abnormality information signal CS2, a switch element that switches the electrical connection between the terminal to which the temperature state signal XHOT2 is input and the output terminal that outputs the temperature abnormality information signal CS2, a switch element that switches the electrical connection between the terminal to which the temperature state signal XHOT3 is input and the output terminal that outputs the temperature abnormality information signal CS2, a switch element that switches the electrical connection between the terminal to which the temperature state signal XHOT4 is input and the output terminal that outputs the temperature abnormality information signal CS2, a switch element that switches the electrical connection between the terminal to which the temperature state signal XHOT5 is input and the output terminal that outputs the temperature abnormality information signal CS2, and a switch element that switches the electrical connection between the terminal to which the temperature state signal XHOT6 is input and the output terminal that outputs the temperature abnormality information signal CS2.

[0092] Even in such a configuration, the conduction state of each switch element is controlled by the information selection signal SEL or a signal obtained by decoding the information selection signal SEL under predetermined conditions, so that the temperature state signal XHOTi can be selected from the temperature state signals XHOT1 to XHOT6 and output as the temperature anomaly information signal CS2. Note that, as the switch element in such a configuration, for example, a FET (Field Effect Transistor) or a transmission gate can be used.

[0093] As described above, the individual information output circuit 320 selects one of the temperature status signals XHOT1 to XHOT6 output by each of the print heads 22-1 to 22-6 in response to the information selection signal SEL output by the acquired information selection control circuit 340, and outputs the temperature status signal XHOTi output by the selected print head 22-i as the temperature abnormality information signal CS2.

[0094] That is, the individual information output circuit 320 selects a temperature state signal XHOTi from the temperature state signals XHOT1 to XHOT6 in response to the information selection signal SEL, and when the selected temperature state signal XHOTi indicates that the temperature of the corresponding drive signal selection circuit 200 is normal and the logic level of the temperature state signal XHOTi is H level, outputs an H level temperature abnormality information signal CS2 containing normal information regardless of the logic level of the temperature state signal XHOT not selected from the temperature state signals XHOT1 to XHOT6 in response to the information selection signal SEL; when the selected temperature state signal XHOTi indicates that the temperature of the corresponding drive signal selection circuit 200 is abnormal and the logic level of the temperature state signal XHOTi is L level, outputs an L level temperature abnormality information signal CS2 containing abnormality information regardless of the logic level of the temperature state signal XHOT not selected from the temperature state signals XHOT1 to XHOT6 in response to the information selection signal SEL.

[0095] In other words, the individual information output circuit 320 individually acquires information on whether the temperature of each of the drive signal selection circuits 200 included in each of the print heads 22-1 to 22-6 of the head unit 20 is normal or not in accordance with the information selection signal SEL, and outputs the information as a temperature abnormality information signal CS2.

[0096] The temperature information output circuit 330 outputs a temperature abnormality information signal CS1, a temperature abnormality information signal CS2, and a temperature abnormality information signal CS according to the information selection signal SEL.

[0097] Specifically, the temperature information output circuit 330 includes a multiplexer 332. The multiplexer 332 receives as input the temperature anomaly information signal CS1 output by the integrated information output circuit 310, the temperature anomaly information signal CS2 output by the individual information output circuit 320, and the information selection signal SEL output by the acquired information selection control circuit 340. The multiplexer 332 selects and outputs either the temperature anomaly information signal CS1 or the temperature anomaly information signal CS2 in accordance with the input information selection signal SEL. The signal output by the multiplexer 332 is output from the temperature information output circuit 330 as the temperature anomaly information signal CS.

[0098] That is, in response to the information selection signal SEL, the temperature information output circuit 330 switches between outputting a temperature abnormality information signal CS1 that corresponds to whether or not all of the temperatures of the drive signal selection circuits 200 included in each of the print heads 22-1 to 22-6 of the head unit 20 are normal, and outputting a temperature abnormality information signal CS2 that corresponds to whether or not each of the drive signal selection circuits 200 included in each of the print heads 22-1 to 22-6 of the head unit 20 is normal.

[0099] The temperature abnormality information signal CS output by the temperature information output circuit 330 is then output from the acquired information selection circuit 300. That is, the temperature information output circuit 330 selects the temperature abnormality information signal CS1 or the temperature abnormality information signal CS2 in accordance with the information selection signal SEL and outputs it as the temperature abnormality information signal CS. The temperature abnormality information signal CS output by the temperature information output circuit 330 is output from the acquired information selection circuit 300 and is also output from the head unit 20 via one terminal TMcs. In other words, the one terminal TMcs that the head unit 20 has outputs the temperature abnormality information signal CS from the head unit 20.

[0100] Here, an example of the information selection signal SEL generated by the acquired information selection control circuit 340 based on the drive data signal DI1 will be described. FIG. 11 is a diagram showing an example of the information selection signal SEL. The acquired information selection control circuit 340 analyzes the input drive data signal DI1 to identify signals that the control circuit 100 requests to be output from the individual information output circuit 320 and the temperature information output circuit 330. Then, the acquired information selection control circuit 340 determines whether the control circuit 100 requests to output the signals from the individual information output circuit 320 and the temperature information output circuit 330. In response to a request from 100, an information selection signal SEL including 3-bit selection data SD [SD1, SD2, SD3] for controlling the multiplexer 322 of the individual information output circuit 320 and the multiplexer 332 of the temperature information output circuit 330 is generated.

[0101] When the acquired information selection circuit 300 receives a drive data signal DI1 requesting acquisition of information indicating whether the temperature of the drive signal selection circuit 200 included in the print head 22-1 is normal, the acquired information selection control circuit 340 generates selection data SD[SD1, SD2, SD3]=[0,0,1] as the information selection signal SEL and outputs it to the individual information output circuit 320 and the temperature information output circuit 330. When the selection data SD[SD1, SD2, SD3]=[0,0,1] is received, the multiplexer 332 included in the temperature information output circuit 330 selects the temperature abnormality information signal CS2 output by the individual information output circuit 320 and outputs it as the temperature abnormality information signal CS, as shown in FIG. 11 . At this time, the multiplexer 322 included in the individual information output circuit 320 receives the same selection data SD[SD1, SD2, SD3]=[0,0,1] as the multiplexer 332. 11, the multiplexer 322 selects the temperature status signal XHOT1 corresponding to the temperature of the drive signal selection circuit 200 of the print head 22-1 and outputs it as the temperature abnormality information signal CS2. As a result, the acquired information selection circuit 300 outputs the temperature status signal XHOT1 corresponding to the temperature of the drive signal selection circuit 200 of the print head 22-1 as the temperature abnormality information signal CS.

[0102] Furthermore, when the acquired information selection circuit 300 receives a drive data signal DI1 requesting acquisition of information on whether the temperature of the drive signal selection circuit 200 included in print head 22-2 is normal, the acquired information selection control circuit 340 generates selection data SD[SD1, SD2, SD3]=[0,1,0] as the information selection signal SEL and outputs it to the individual information output circuit 320 and the temperature information output circuit 330. When the selection data SD[SD1, SD2, SD3]=[0,1,0] is received, the multiplexer 332 included in the temperature information output circuit 330 selects the temperature abnormality information signal CS2 output by the individual information output circuit 320 and outputs it as the temperature abnormality information signal CS, as shown in FIG. 11 . At this time, the multiplexer 322 included in the individual information output circuit 320 receives the same selection data SD[SD1, SD2, SD3]=[0,1,0] as the multiplexer 332. 11, the multiplexer 322 selects the temperature status signal XHOT2 corresponding to the temperature of the drive signal selection circuit 200 of the print head 22-2 and outputs it as the temperature abnormality information signal CS2. As a result, the acquired information selection circuit 300 outputs the temperature status signal XHOT2 corresponding to the temperature of the drive signal selection circuit 200 of the print head 22-2 as the temperature abnormality information signal CS.

[0103] Furthermore, when the acquired information selection circuit 300 receives a drive data signal DI1 requesting acquisition of information indicating whether the temperature of the drive signal selection circuit 200 included in the print head 22-3 is normal, the acquired information selection control circuit 340 generates selection data SD[SD1, SD2, SD3]=[0, 1, 1] as the information selection signal SEL and outputs it to the individual information output circuit 320 and the temperature information output circuit 330. When the selection data SD[SD1, SD2, SD3]=[0, 1, 1] is received, the multiplexer 332 included in the temperature information output circuit 330 selects the temperature abnormality information signal CS2 output by the individual information output circuit 320 and outputs it as the temperature abnormality information signal CS, as shown in FIG. 11 . At this time, the multiplexer 322 included in the individual information output circuit 320 receives the same selection data SD[SD1, SD2, SD3]=[0, 1, 1] as the multiplexer 332. 11, the multiplexer 322 selects the temperature status signal XHOT3 corresponding to the temperature of the drive signal selection circuit 200 of the print head 22-3 and outputs it as the temperature abnormality information signal CS2. As a result, the acquired information selection circuit 300 outputs the temperature status signal XHOT3 corresponding to the temperature of the drive signal selection circuit 200 of the print head 22-3 as the temperature abnormality information signal CS. and output it.

[0104] Furthermore, when the drive data signal DI1 requesting acquisition of information on whether the temperature of the drive signal selection circuit 200 included in the print head 22-4 is normal is input to the acquired information selection circuit 300, the acquired information selection control circuit 340 generates selection data SD[SD1, SD2, SD3]=[1, 0, 0] as the information selection signal SEL and outputs it to the individual information output circuit 320 and the temperature information output circuit 330. When the selection data SD[SD1, SD2, SD3]=[1, 0, 0] is input, the multiplexer 332 included in the temperature information output circuit 330 selects the temperature abnormality information signal CS2 output by the individual information output circuit 320 and outputs it as the temperature abnormality information signal CS, as shown in FIG. 11. At this time, the multiplexer 322 included in the individual information output circuit 320 has input thereto the same selection data SD[SD1, SD2, SD3]=[1, 0, 0] as the multiplexer 332. 11, the multiplexer 322 selects the temperature status signal XHOT4 corresponding to the temperature of the drive signal selection circuit 200 of the print head 22-4 and outputs it as the temperature abnormality information signal CS2. As a result, the acquired information selection circuit 300 outputs the temperature status signal XHOT4 corresponding to the temperature of the drive signal selection circuit 200 of the print head 22-4 as the temperature abnormality information signal CS.

[0105] Furthermore, when the acquired information selection circuit 300 receives a drive data signal DI1 requesting acquisition of information on whether the temperature of the drive signal selection circuit 200 included in the print head 22-5 is normal, the acquired information selection control circuit 340 generates selection data SD[SD1, SD2, SD3]=[1, 0, 1] as the information selection signal SEL and outputs it to the individual information output circuit 320 and the temperature information output circuit 330. When the selection data SD[SD1, SD2, SD3]=[1, 0, 1] is received, the multiplexer 332 included in the temperature information output circuit 330 selects the temperature abnormality information signal CS2 output by the individual information output circuit 320 and outputs it as the temperature abnormality information signal CS, as shown in FIG. 11 . At this time, the multiplexer 322 included in the individual information output circuit 320 receives the same selection data SD[SD1, SD2, SD3]=[1, 0, 1] as the multiplexer 332. 11, the multiplexer 322 selects the temperature status signal XHOT5 corresponding to the temperature of the drive signal selection circuit 200 of the print head 22-5 and outputs it as the temperature abnormality information signal CS2. As a result, the acquired information selection circuit 300 outputs the temperature status signal XHOT5 corresponding to the temperature of the drive signal selection circuit 200 of the print head 22-5 as the temperature abnormality information signal CS.

[0106] Furthermore, when the drive data signal DI1 requesting acquisition of information on whether the temperature of the drive signal selection circuit 200 included in the print head 22-6 is normal is input to the acquired information selection circuit 300, the acquired information selection control circuit 340 generates selection data SD[SD1, SD2, SD3]=[1,1,0] as the information selection signal SEL and outputs it to the individual information output circuit 320 and the temperature information output circuit 330. When the selection data SD[SD1, SD2, SD3]=[1,1,0] is input, the multiplexer 332 included in the temperature information output circuit 330 selects the temperature abnormality information signal CS2 output by the individual information output circuit 320 and outputs it as the temperature abnormality information signal CS, as shown in FIG. 11 . At this time, the multiplexer 322 included in the individual information output circuit 320 has input thereto the same selection data SD[SD1, SD2, SD3]=[1,1,0] as the multiplexer 332. 11, the multiplexer 322 selects the temperature status signal XHOT6 corresponding to the temperature of the drive signal selection circuit 200 of the print head 22-6 and outputs it as the temperature abnormality information signal CS2. As a result, the acquired information selection circuit 300 outputs the temperature status signal XHOT6 corresponding to the temperature of the drive signal selection circuit 200 of the print head 22-6 as the temperature abnormality information signal CS.

[0107] As described above, when the temperature information output circuit 330 outputs the temperature abnormality information signal CS2 as the temperature abnormality information signal CS, the information selection signal SEL output by the acquired information selection control circuit 340 selects one of the temperature state signals XHOT1 to XHOT6.

[0108] Furthermore, when the acquired information selection circuit 300 receives a drive data signal DI1 requesting acquisition of information on whether all temperatures of the drive signal selection circuits 200 included in each of the print heads 22-1 to 22-6 are normal, the acquired information selection control circuit 340 generates selection data SD[SD1, SD2, SD3]=[1,1,1] as the information selection signal SEL and outputs it to the individual information output circuit 320 and the temperature information output circuit 330. When the selection data SD[SD1, SD2, SD3]=[1,1,1] is received, the multiplexer 332 included in the temperature information output circuit 330 selects the temperature abnormality information signal CS1 output by the integrated information output circuit 310 and outputs it as the temperature abnormality information signal CS, as shown in FIG. 11. At this time, the integrated information output circuit 310 outputs the temperature abnormality information signal CS1 indicating whether all temperatures of the drive signal selection circuits 200 included in each of the print heads 22-1 to 22-6 of the head unit 20 are normal. As a result, the acquired information selection circuit 300 outputs a temperature abnormality information signal CS1 according to information on whether or not all of the temperatures of the drive signal selection circuits 200 included in each of the print heads 22-1 to 22-6 are normal as the temperature abnormality information signal CS.

[0109] Furthermore, the multiplexer 322 included in the individual information output circuit 320 receives the same selection data SD[SD1, SD2, SD3]=[1,1,1] as the multiplexer 332. Therefore, as shown in Fig. 11, the multiplexer 322 does not select any of the temperature status signals XHOT1 to XHOT6 output by the print heads 22-1 to 22-6. In other words, when the temperature information output circuit 330 outputs the temperature abnormality information signal CS1 as the temperature abnormality information signal CS, the information selection signal SEL output by the acquired information selection control circuit 340 does not select any of the temperature status signals XHOT1 to XHOT6.

[0110] As shown in FIG. 11 , when the acquired information selection control circuit 340 outputs the selection data SD[SD1, SD2, SD3]=[0,0,0] or the selection data SD[SD1, SD2, SD3]=[1,1,1] as the information selection signal SEL to the individual information output circuit 320, the multiplexer 322 of the individual information output circuit 320 selects none of the temperature status signals XHOT1 to XHOT6. In this case, the multiplexer 322 electrically disconnects the input terminals to which the temperature status signals XHOT1 to XHOT6 are input from the output terminal that outputs the temperature anomaly information signal CS2, thereby placing the output terminal that outputs the temperature anomaly information signal CS2 in a high-impedance state. In this case, the multiplexer 322 may output a constant temperature anomaly information signal CS2 at a predetermined voltage. Here, the predetermined voltage may be, for example, the power supply voltage of the multiplexer 322 or the ground potential.

[0111] Similarly, as shown in FIG. 11 , when the acquired information selection control circuit 340 outputs selection data SD[SD1, SD2, SD3]=[0,0,0] as the information selection signal SEL to the temperature information output circuit 330, the multiplexer 332 included in the temperature information output circuit 330 does not select the temperature anomaly information signal CS1 or the temperature anomaly information signal CS2. In this case, the multiplexer 332 electrically disconnects the input terminal to which the temperature anomaly information signal CS1 is input and the input terminal to which the temperature anomaly information signal CS2 is input from the output terminal that outputs the temperature anomaly information signal CS, thereby placing the output terminal that outputs the temperature anomaly information signal CS2 in a high-impedance state. In this case, the multiplexer 332 may output a constant temperature anomaly information signal CS at a predetermined voltage value. Here, the predetermined voltage value may be, for example, the voltage value of the power supply voltage of the multiplexer 332 or the ground potential.

[0112] As described above, in the acquired information selection circuit 300 of the first embodiment, the acquired information selection control circuit 340 generates the information selection signal SEL based on the drive data signal DI1, and based on the information selection signal SEL, acquires information on whether all of the temperatures of the drive signal selection circuits 200 included in each of the print heads 22-1 to 22-6 are normal, or information on whether the temperature of each of the drive signal selection circuits 200 included in each of the print heads 22-1 to 22-6 is normal, and outputs this as a temperature abnormality information signal CS. The temperature abnormality information signal CS output by the acquired information selection circuit 300 is then output from the head unit 20 via one terminal TMcs that the head unit 20 has.

[0113] Here, an optimum example of a method for determining whether or not there is a temperature abnormality in the drive signal selection circuit 200 included in each of the print heads 22-1 to 22-6 using the acquired information selection circuit 300 configured as described above will be described.

[0114] FIG. 12 is a diagram showing an example of a method for determining whether or not there is a temperature abnormality in the drive signal selection circuit 200 included in each of the print heads 22-1 to 22-6.

[0115] In the liquid ejector 1, when the process of determining whether or not there is a temperature abnormality in the drive signal selection circuit 200 included in each of the print heads 22-1 to 22-6 is performed, the control circuit 100 assigns "1" to the variable i as an initial setting (step S100). Thereafter, the control circuit 100 executes an integrated determination step of comprehensively determining whether or not there is an abnormality in the print heads 22-1 to 22-6. Note that the process of determining whether or not there is a temperature abnormality in the drive signal selection circuit 200 included in each of the print heads 22-1 to 22-6 may be performed at any timing, such as based on a user request, or may be performed at any timing that includes the entire period during which the liquid ejector 1 is operating.

[0116] Specifically, the control circuit 100 generates and outputs a drive data signal DI1 for selecting the temperature abnormality information signal CS1 output by the integrated information output circuit 310 and outputting it as the temperature abnormality information signal CS, the drive data signal DI1 being for causing the acquired information selection control circuit 340 to output selection data SD[SD1, SD2, SD3]=[1, 1, 1] as the information selection signal SEL (step S110). As a result, the acquired information selection circuit 300 outputs the temperature abnormality information signal CS1, the logic level of which changes depending on whether all of the temperatures of the drive signal selection circuits 200 included in each of the print heads 22-1 to 22-6 of the head unit 20 are normal, to the control circuit 100 as the temperature abnormality information signal CS.

[0117] The control circuit 100 determines whether all of the temperatures of the drive signal selection circuits 200 included in each of the print heads 22-1 to 22-6 of the head unit 20 are normal, and whether a temperature abnormality has occurred in the head unit 20, based on the logic level of the input temperature abnormality information signal CS. Specifically, the control circuit 100 determines whether the logic level of the input temperature abnormality information signal CS is H level (step S120). If the control circuit 100 determines that the logic level of the input temperature abnormality information signal CS is H level (Y in step S120), the control circuit 100 determines that all of the temperatures of the drive signal selection circuits 200 included in each of the print heads 22-1 to 22-6 of the head unit 20 are normal (step S130), and ends the process of determining whether or not a temperature abnormality has occurred in the drive signal selection circuits 200 included in each of the print heads 22-1 to 22-6. At this time, the control circuit 100 may notify the user via a notifying unit (not shown) that the temperatures of all of the drive signal selection circuits 200 included in each of the print heads 22-1 to 22-6 of the head unit 20 are normal.

[0118] On the other hand, if the control circuit 100 determines that the logic level of the temperature abnormality information signal CS is not H level (N in step S120), that is, if the control circuit 100 determines that the logic level of the temperature abnormality information signal CS is not H level (N in step S120), If the control circuit 100 determines that the logical level of the temperature abnormality information signal CS is at L level, it determines that a temperature abnormality has occurred in the drive signal selection circuit 200 included in any of the print heads 22-1 to 22-6 of the head unit 20, and executes an individual determination process to individually determine whether or not there is an abnormality in the print heads 22-1 to 22-6.

[0119] In executing the individual determination step, the control circuit 100 generates and outputs a drive data signal DI1 that causes the individual information output circuit 320 to select the temperature state signal XHOT1 and the temperature information output circuit 330 to select the temperature abnormality information signal CS1 and output it as the temperature abnormality information signal CS, and that causes the acquired information selection control circuit 340 to output selection data SD[SD1, SD2, SD3]=[0,0,1] as the information selection signal SEL (step S140). As a result, the acquired information selection circuit 300 outputs the temperature state signal XHOT1 corresponding to the temperature of the drive signal selection circuit 200 included in the print head 22-1 of the head unit 20 to the control circuit 100 as the temperature abnormality information signal CS.

[0120] Based on the logic level of the input temperature abnormality information signal CS, the control circuit 100 determines whether a temperature abnormality has occurred in the drive signal selection circuit 200 of the print head 22-1 corresponding to the temperature status signal XHOT1 (step S150). Specifically, if the input temperature abnormality information signal CS is at H level, the control circuit 100 determines that the temperature of the drive signal selection circuit 200 of the print head 22-1 corresponding to the temperature status signal XHOT1 is normal, and if the input temperature abnormality information signal CS is at L level, the control circuit 100 determines that the temperature of the drive signal selection circuit 200 of the print head 22-1 corresponding to the temperature status signal XHOT1 is abnormal. The control circuit 100 then retains the determination result (step S160).

[0121] Thereafter, the control circuit 100 determines whether the variable i is less than 6 (step S170), and if the control circuit 100 determines that the variable i is less than 6 (Y in step S170), the control circuit 100 adds 1 to the variable i (step S180) and repeatedly executes steps S140 to S170 described above. That is, the control circuit 100 causes the acquired information selection circuit 300 to output, in order, temperature status signals XHOT2 to XHOT6 corresponding to the temperatures of the drive signal selection circuits 200 included in the print heads 22-2 to 22-6 of the head unit 20 as temperature abnormality information signals CS, and sequentially determines whether the temperatures of the drive signal selection circuits 200 included in the print heads 22-2 to 22-6 corresponding to the temperature status signals XHOT2 to XHOT6 are normal based on the logic levels of the input temperature abnormality information signals CS, and stores the determination results. That is, in the individual determination step, the control circuit 100 determines whether the temperature of the drive signal selection circuit 200 of each of the print heads 22-1 to 22-6 is normal or not, and stores the determination results.

[0122] Then, the control circuit 100 completes the process of determining whether or not the temperature of the drive signal selection circuit 200 included in each of the print heads 22-1 to 22-6 in the head unit 20 is normal, upon which the control circuit 100 completes the process of determining whether or not the temperature of the drive signal selection circuit 200 included in each of the print heads 22-1 to 22-6 is abnormal. At this time, the control circuit 100 may notify the user of the retained determination result via a notifying unit (not shown).

[0123] That is, in the liquid ejection device 1 of the first embodiment, when the temperature abnormality information signal CS1 input as the temperature abnormality information signal CS contains abnormality information and is at H level, the control circuit 100 acquires the temperature abnormality information signal CS2 as the temperature abnormality information signal CS, and identifies the location of the temperature abnormality among the print heads 22-1 to 22-6 based on the temperature abnormality information signal CS2 as the temperature abnormality information signal CS. That is, when the temperature abnormality information signal CS1 contains abnormality information, the control circuit 100 identifies the abnormal location from the multiple drive signal selection circuits 200 that the print heads 22-1 to 22-6 have based on the temperature abnormality information signal CS2. In other words, the head unit 20 acquires the temperature abnormality information signal CS2 as the temperature abnormality information signal CS. When the temperature abnormality information signal CS1 to be output contains abnormality information and is at H level, the temperature abnormality information signal CS2 is output as the temperature abnormality information signal CS, thereby identifying the location where the temperature abnormality has occurred in the print heads 22-1 to 22-6 of the head unit 20.

[0124] Here, the ejection section 600 of print head 22-1 is an example of a first ejection section, the piezoelectric element 60 included in the ejection section 600 of print head 22-1 is an example of a first drive element, the drive signal selection circuit 200 of print head 22-1 is an example of a first drive control circuit, and the temperature abnormality detection circuit 400 of print head 22-1 is an example of a first temperature detection circuit. Also, the ejection section 600 of print head 22-2 is an example of a second ejection section, the piezoelectric element 60 included in the ejection section 600 of print head 22-2 is an example of a second drive element, the drive signal selection circuit 200 of print head 22-2 is an example of a second drive control circuit, and the temperature abnormality detection circuit 400 of print head 22-2 is an example of a second temperature detection circuit. Furthermore, the multiple ejection sections 600 of the head unit 20 including the print heads 22-1 and 22-2 are an example of multiple ejection sections, the multiple drive signal selection circuits 200 of the head unit 20 including the print heads 22-1 and 22-2 are an example of multiple drive control circuits, and the multiple temperature abnormality detection circuits 400 of the head unit 20 including the print heads 22-1 and 22-2 are an example of multiple temperature detection circuits. Furthermore, in the multiplexer 322 of the individual information output circuit 320, the terminal to which the temperature state signal XHOT1 is input is an example of a first input terminal, the terminal to which the temperature state signal XHOT2 is input is an example of a second input terminal, the terminal to which the temperature state signals XHOT1 to XHOT6 are input are an example of multiple input terminals, and the terminal that outputs the temperature abnormality information signal CS2 is an example of a selected information output terminal.

[0125] Furthermore, the temperature state signal XHOT1 is an example of a first state signal, the temperature state signal XHOT2 is an example of a second state signal, the temperature state signals XHOT1 to XHOT6 are examples of multiple detection results, the information selection signal SEL is an example of a selection signal, and among the temperature state signals XHOT1 to XHOT6, a signal selected by the information selection signal SEL in the individual information output circuit 320 is an example of a selected detection result, and among the temperature state signals XHOT1 to XHOT6, a signal not selected by the information selection signal SEL in the individual information output circuit 320 is an example of a non-selected detection result. Furthermore, the temperature abnormality information signal CS1 output by the integrated information output circuit 310 is an example of a first temperature abnormality information signal, the temperature abnormality information signal CS2 output by the individual information output circuit 320 is an example of a second temperature abnormality information signal, and the temperature abnormality information signal CS output by the temperature information output circuit 330 is an example of a temperature abnormality information signal and a temperature information signal. Furthermore, the terminal TMcs that outputs the temperature abnormality information signal CS from the head unit 20 is an example of a temperature information output terminal.

[0126] 1.7 Effects As described above, the head unit 20 of the liquid ejection device 1 of the first embodiment has an integrated information output circuit 310 that outputs a temperature abnormality information signal CS1 in response to the temperature state signals XHOT1 to XHOT6 detected by the multiple temperature abnormality detection circuits 400, an individual information output circuit 320 that outputs a temperature abnormality information signal CS2 in response to a signal selected from the temperature state signals XHOT1 to XHOT6 in response to the information selection signal SEL, and a temperature information output circuit 330 that outputs the temperature abnormality information signal CS1, the temperature abnormality information signal CS2, and the temperature abnormality information signal CS in response to the information selection signal SEL. As a result, the temperature information output circuit 330 selects, in accordance with the information selection signal SEL, a temperature abnormality information signal CS1 corresponding to the temperature state signals XHOT1 to XHOT6 detected by the plurality of temperature abnormality detection circuits 400, and a temperature abnormality information signal CS2 corresponding to one of the temperature state signals XHOT1 to XHOT6, and outputs the selected signal as a single signal, the temperature abnormality information signal CS, and the head unit 20 can output the single signal, the temperature abnormality information signal CS, via a single terminal TMcs. In one embodiment, even when head unit 20 has multiple print heads 22-1 to 22-6, it is possible to output an integrated detection result of the presence or absence of temperature abnormalities for each of the multiple print heads 22-1 to 22-6 and an individual detection result of the presence or absence of temperature abnormalities for each of the multiple print heads 22-1 to 22-6, without increasing the number of terminals and signal lines that output the detection result of the presence or absence of temperature abnormalities for each of the multiple print heads 22-1 to 22-6.

[0127] Furthermore, in the head unit 20 of the first embodiment, when the temperature status signal XHOTi is selected in response to the information selection signal SEL, the individual information output circuit 320 electrically connects the input terminal to which the temperature status signal XHOTi is input and the output terminal to which the temperature abnormality information signal CS2 is output, and electrically disconnects the input terminals other than the input terminal to which the temperature status signal XHOTi is input from the output terminal to which the temperature abnormality information signal CS2 is output. This reduces the risk that a signal not selected in response to the information selection signal SEL will affect the output temperature abnormality information signal CS2, improving the accuracy of the detection results output by the temperature information output circuit 330, which individually detect the presence or absence of a temperature abnormality for each of the multiple print heads 22-1 to 22-6. In this case, by configuring the individual information output circuit 320 to include a multiplexer 322, as shown in the head unit 20 of the first embodiment, the circuit configuration of the individual information output circuit 320 is less likely to become complicated, and the individual information output circuit 320 can be made more compact.

[0128] Furthermore, in the head unit 20 of the first embodiment, when the information selection signal SEL does not select any of the temperature state signals XHOT1 to XHOT6, the individual information output circuit 320 electrically disconnects the terminal to which the temperature state signals XHOT1 to XHOT6 are input to the individual information output circuit 320 from the terminal to which the temperature abnormality information signal CS2 is output from the individual information output circuit 320. In this case, when the information selection signal SEL does not select any of the temperature state signals XHOT1 to XHOT6, the individual information output circuit 320 may output a constant signal at a predetermined voltage value as the temperature abnormality information signal CS2. This reduces the risk of unintended malfunction of the head unit 20 in accordance with the output of the individual information output circuit 320, even if the signal quality of the information selection signal SEL input to the individual information output circuit 320 is reduced due to the influence of external noise or the like.

[0129] Furthermore, in the head unit 20 of the first embodiment, when the temperature abnormality detection circuit 400 of the print head 22-i outputs a temperature status signal XHOTi that goes to L level when it detects a temperature abnormality in the drive signal selection circuit 200 of the print head 22-i and goes to H level when it does not detect a temperature abnormality in the drive signal selection circuit 200 of the print head 22-i, the integrated information output circuit 310 is configured to include an AND circuit 312. This reduces the risk that the circuit configuration of the integrated information output circuit 310 will become complicated, and the integrated information output circuit 310 can be made smaller.

[0130] 2. Second embodiment Next, a description will be given of a liquid ejection device 1 and a head unit 20 according to a second embodiment. In describing the liquid ejection device 1 and the head unit 20 according to the second embodiment, the same components as those in the liquid ejection device 1 and the head unit 20 according to the first embodiment will be given the same reference numerals, and the description thereof will be omitted or simplified.

[0131] 13 is a diagram showing an example of the configuration of an acquired information selection circuit 300 of the second embodiment. As shown in FIG. 13, the liquid ejection device 1 and head unit 20 of the second embodiment differ from the liquid ejection device 1 and head unit 20 of the first embodiment in that the temperature abnormality information signal CS output by the temperature information output circuit 330 is input to an acquired information selection control circuit 340. At this time, the acquired information selection control circuit 340 generates an information selection signal SEL based on the analysis result of the command included in the drive data signal DI1 and the input temperature abnormality information signal CS, and selects individual information The temperature information output circuit 320 and the temperature information output circuit 330 are output, and a temperature information signal ICS is generated based on the temperature abnormality information signal CS, and the generated temperature information signal ICS is output from the head unit 20 via the terminal TMcs in place of the temperature abnormality information signal CS. In this respect as well, the liquid ejection device 1 and head unit 20 differ from the liquid ejection device 1 and head unit 20 of the first embodiment.

[0132] Specifically, in the liquid ejection device 1 and head unit 20 of the second embodiment, when a drive data signal DI1 requesting acquisition of information on whether all temperatures of the drive signal selection circuits 200 included in each of the print heads 22-1 to 22-6 are normal is input to the acquired information selection control circuit 340, the acquired information selection control circuit 340 generates an information selection signal SEL including selection data SD[SD1, SD2, SD3] according to the content shown in FIG. 11 and outputs it to the individual information output circuit 320 and the temperature information output circuit 330. As a result, a temperature abnormality information signal CS indicating whether all temperatures of the drive signal selection circuits 200 included in each of the print heads 22-1 to 22-6 of the head unit 20 are normal is input to the acquired information selection control circuit 340. The acquired information selection control circuit 340 determines whether all temperatures of the drive signal selection circuits 200 included in each of the print heads 22-1 to 22-6 are normal according to the logic level of the input temperature abnormality information signal CS, and generates a temperature information signal ICS according to the determination result. The acquired information selection control circuit 340 then outputs the generated temperature information signal ICS from the head unit 20 via the terminal TMcs.

[0133] Furthermore, in the liquid ejection device 1 and head unit 20 of the second embodiment, when a drive data signal DI1 requesting acquisition of information on whether the temperature of the drive signal selection circuit 200 included in the print head 22-i is normal is input to the acquired information selection control circuit 340, the acquired information selection control circuit 340 generates an information selection signal SEL including selection data SD[SD1, SD2, SD3] according to the content shown in FIG. 11 and outputs it to the individual information output circuit 320 and the temperature information output circuit 330. As a result, a temperature abnormality information signal CS indicating whether the temperature of the drive signal selection circuit 200 included in the print head 22-i of the head unit 20 is normal is input to the acquired information selection control circuit 340. The acquired information selection control circuit 340 determines whether the temperature of the drive signal selection circuit 200 included in the print head 22-i is normal based on the logic level of the input temperature abnormality information signal CS, and generates a temperature information signal ICS according to the determination result. The acquired information selection control circuit 340 then outputs the generated temperature information signal ICS from the head unit 20 via the terminal TMcs.

[0134] That is, in the liquid ejection device 1 and head unit 20 of the second embodiment, the acquired information selection control circuit 340 generates an information selection signal SEL in response to the input drive data signal DI1, and acquires the temperature abnormality information signal CS output by the temperature information output circuit 330. Then, in response to the acquired temperature abnormality information signal CS, the acquired information selection control circuit 340 determines whether the temperatures of the drive signal selection circuits 200 included in each of the print heads 22-1 to 22-6 of the head unit 20 specified by the drive data signal DI1 are normal or not, and outputs a temperature information signal ICS in response to the determination result from the head unit 20 via the terminal TMcs. At this time, the temperature information signal ICS output by the acquired information selection control circuit 340 may be a signal of the same logical level as the temperature abnormality information signal CS, or may be a predetermined command indicating whether the temperatures of the drive signal selection circuits 200 included in each of the print heads 22-1 to 22-6 are normal or not.

[0135] Furthermore, in the liquid ejection device 1 and head unit 20 of the second embodiment, when a drive data signal DI1 requesting a process for determining whether or not there is a temperature abnormality in the drive signal selection circuit 200 included in each of the print heads 22-1 to 22-6 is input to the acquired information selection control circuit 340, the acquired information selection control circuit 340 executes the process for determining whether or not there is a temperature abnormality in the drive signal selection circuit 200 included in each of the print heads 22-1 to 22-6 shown in Figure 12 in place of the control circuit 100.

[0136] Specifically, when a drive data signal DI1 requesting a determination process for the presence or absence of a temperature abnormality in the drive signal selection circuits 200 included in each of print heads 22-1 to 22-6 is input to the acquired information selection control circuit 340, the acquired information selection control circuit 340 executes an integrated determination process for comprehensively determining the presence or absence of an abnormality in the print heads 22-1 to 22-6 described above, in place of the control circuit 100. Then, if the acquired information selection control circuit 340 determines in the integrated determination process that the temperatures of all of the drive signal selection circuits 200 included in each of print heads 22-1 to 22-6 of the head unit 20 are normal, it generates a temperature information signal ICS including information that the temperatures of all of the drive signal selection circuits 200 included in each of print heads 22-1 to 22-6 of the head unit 20 are normal, and outputs the generated temperature information signal ICS from the head unit 20 via the terminal TMcs.

[0137] On the other hand, if, in the integrated determination step, the acquired information selection control circuit 340 determines that a temperature abnormality has occurred in the drive signal selection circuit 200 included in any of the print heads 22-1 to 22-6 of the head unit 20, the acquired information selection control circuit 340 determines that a temperature abnormality has occurred in the drive signal selection circuit 200 included in any of the print heads 22-1 to 22-6 of the head unit 20, and executes an individual determination step to individually determine whether or not there is an abnormality in the print heads 22-1 to 22-6. In this individual determination step, the acquired information selection control circuit 340 individually determines whether or not the temperature of the drive signal selection circuit 200 included in the print heads 22-1 to 22-6 is normal, and retains the determination result. Then, when the acquired information selection control circuit 340 has completed determining whether the temperature of the drive signal selection circuit 200 in each of the print heads 22-1 to 22-6 in the head unit 20 is normal, it generates a temperature information signal ICS including information on the determination result as to whether or not there is a temperature abnormality in the drive signal selection circuit 200 included in each of the print heads 22-1 to 22-6 it holds, and outputs the generated temperature information signal ICS from the head unit 20 via the terminal TMcs.

[0138] That is, in the liquid ejection device 1 and head unit 20 of the second embodiment, when the temperature abnormality information signal CS1 input as the temperature abnormality information signal CS contains abnormality information and is at an H level, the acquired information selection control circuit 340 acquires a temperature abnormality information signal CS2 as the temperature abnormality information signal CS and identifies the location of the temperature abnormality among the print heads 22-1 to 22-6 based on the temperature abnormality information signal CS2. The acquired information selection control circuit 340 then generates a temperature information signal ICS containing information about the location of the temperature abnormality among the identified print heads 22-1 to 22-6, and outputs the generated temperature information signal ICS from the head unit 20 via the terminal TMcs. In other words, when the temperature abnormality information signal CS1 contains abnormality information, the acquired information selection control circuit 340 identifies the location of the abnormality from the multiple drive signal selection circuits 200 of the print heads 22-1 to 22-6 based on the temperature abnormality information signal CS2.

[0139] In the liquid ejection device 1 and head unit 20 of the second embodiment, in addition to the effects of the liquid ejection device 1 and head unit 20 of the first embodiment described above, the processing load on the control circuit 100 can be reduced.

[0140] Here, in the liquid ejection device 1 and head unit 20 of the second embodiment, the acquired information selection control circuit 340 is an example of an abnormality location identification circuit, and the temperature information signal ICS output by the acquired information selection control circuit 340 is an example of a temperature information signal.

[0141] 3. Third embodiment Next, a liquid ejection device 1 and a head unit 20 according to a third embodiment will be described. In describing the liquid ejection device 1 and the head unit 20 according to the third embodiment, the same configurations as those of the liquid ejection device 1 and the head unit 20 according to the first and second embodiments will be described. In the liquid ejection device 1 of the third embodiment, the logical levels of the temperature status signals XHOT1 to XHOT6 output by the temperature abnormality detection circuits 400 included in each of the print heads 22-1 to 22-6 are different from those of the liquid ejection device 1 and head unit 20 of the first embodiment.

[0142] 14 is a diagram showing an example of the configuration of a temperature abnormality detection circuit 400 according to the second embodiment. As shown in Fig. 14, in the temperature abnormality detection circuit 400 according to the second embodiment, a voltage signal Vdet whose voltage value changes with temperature is input to a positive input terminal of a comparator 440, and a voltage signal Vref output by a reference voltage generation circuit 430 is input to a negative input terminal of the comparator 440. Therefore, in the temperature abnormality detection circuit 400 according to the second embodiment, the comparator 440 outputs a signal whose voltage value is the L level of the ground potential when the voltage signal Vdet is smaller than the voltage value of the voltage signal Vref, and whose voltage value is the H level of the voltage signal VDD when the voltage signal Vdet is greater than the voltage value of the voltage signal Vref.

[0143] The signal output by the comparator 440 is input to the gate terminal of the transistor 460, causing the temperature abnormality detection circuit 400 to output an H-level temperature status signal XHOT if the temperature of the drive signal selection circuit 200 is outside the temperature range in which the drive signal selection circuit 200 can stably operate, and to output an L-level temperature status signal XHOT if the temperature of the drive signal selection circuit 200 is within the temperature range in which the drive signal selection circuit 200 can stably operate. In other words, the temperature abnormality detection circuit 400 of the third embodiment outputs an H-level temperature status signal XHOT if the temperature of the corresponding drive signal selection circuit 200 is abnormal, and outputs an L-level temperature status signal XHOT if the temperature of the corresponding drive signal selection circuit 200 is normal.

[0144] Fig. 15 is a diagram showing an example of the configuration of an acquired information selection circuit 300 of the third embodiment. As shown in Fig. 15, in the liquid ejection device 1 and head unit 20 of the third embodiment, the integrated information output circuit 310 outputs a temperature abnormality information signal CS1 that is the detection result of the presence or absence of temperature abnormalities in the multiple drive signal selection circuits 200 detected by each of the multiple temperature abnormality detection circuits 400 that the head unit 20 has, and that corresponds to the temperature state signals XHOT1 to XHOT6.

[0145] Specifically, the integrated information output circuit 310 includes an OR circuit 314. The OR circuit 314 receives the temperature status signals XHOT1 to XHOT6 output by the print heads 22-1 to 22-6, respectively. The OR circuit 314 then outputs a signal corresponding to the logic levels of the input temperature status signals XHOT1 to XHOT6. The signal output by the OR circuit 314 is output from the integrated information output circuit 310 as the temperature abnormality information signal CS1.

[0146] As described above, in the liquid ejection device 1 of the third embodiment, the temperature status signals XHOT1 to XHOT6 output by each of the print heads 22-1 to 22-6 are L level when the temperature of the corresponding drive signal selection circuit 200 is normal, and are H level when the temperature of the corresponding drive signal selection circuit 200 is abnormal. By inputting these temperature status signals XHOT1 to XHOT6 to the OR circuit 314, the integrated information output circuit 310 outputs a temperature abnormality information signal CS1 that is L level when the temperatures of all of the drive signal selection circuits 200 included in each of the print heads 22-1 to 22-6 are normal, and is H level when an abnormality has occurred in the temperature of at least one of the drive signal selection circuits 200 included in each of the print heads 22-1 to 22-6.

[0147] That is, in the liquid ejection device 1 of the third embodiment, the temperature abnormality detection circuit 400 of the print head 22-i detects whether or not there is a temperature abnormality in the drive signal selection circuit 200 of the print head 22-i, and outputs a temperature status signal XHOTi that goes to H level when it detects a temperature abnormality in the drive signal selection circuit 200 of the print head 22-i, and goes to L level when it does not detect a temperature abnormality in the drive signal selection circuit 200 of the print head 22-i. At this time, the integrated information output circuit 310 is configured to include an OR circuit 314. As a result, when all of the temperature state signals XHOT1 to XHOT6 indicate normality, the integrated information output circuit 310 outputs a temperature abnormality information signal CS1 of L level, which is a temperature abnormality information signal CS1 containing normality information, and when at least one of the temperature state signals XHOT1 to XHOT6 indicates abnormality, the integrated information output circuit 310 outputs a temperature abnormality information signal CS1 of H level, which is a temperature abnormality information signal CS1 containing abnormality information.

[0148] In other words, the integrated information output circuit 310 of the third embodiment also integrates information on whether the temperatures of the drive signal selection circuits 200 included in each of the print heads 22-1 to 22-6 of the head unit 20 are normal, and outputs a temperature abnormality information signal CS1 whose logic level changes depending on whether the temperatures of all of the drive signal selection circuits 200 included in each of the print heads 22-1 to 22-6 of the head unit 20 are normal. Note that the integrated information output circuit 310 of the third embodiment may be configured to include a circuit equivalent to an OR circuit instead of the OR circuit 314.

[0149] The liquid ejection device 1 of the third embodiment configured as above also achieves the same effects as the liquid ejection device 1 and head unit 20 of the first embodiment described above.

[0150] 4. Fourth embodiment Next, a liquid ejection device 1 and a head unit 20 of a fourth embodiment will be described. In describing the liquid ejection device 1 and the head unit 20 of the fourth embodiment, the same components as those of the liquid ejection device 1 and the head unit 20 of the first, second, and third embodiments will be assigned the same reference numerals, and their description will be omitted or simplified. In the liquid ejection device 1 of the fourth embodiment, the configuration of the temperature information output circuit 330 included in the acquired information selection circuit 300 differs from that of the liquid ejection device 1 and the head unit 20 of the first, second, and third embodiments.

[0151] 16 is a diagram showing an example of the configuration of the acquired information selection circuit 300 of the fourth embodiment. The temperature information output circuit 330 in the liquid ejection device 1 and head unit 20 of the fourth embodiment outputs a temperature abnormality information signal CS1, a temperature abnormality information signal CS2, and a temperature abnormality information signal CS corresponding to the information selection signal SEL.

[0152] Specifically, the temperature information output circuit 330 includes an AND circuit 334 and a resistor 336. The AND circuit 334 receives the temperature anomaly information signal CS1 output by the integrated information output circuit 310 and the information selection signal SEL output by the acquired information selection control circuit 340. When the logic levels of the selection data SD[SD1, SD2, SD3] input as the information selection signal SEL are all H level and the selection data SD[SD1, SD2, SD3]=[1,1,1], the AND circuit 334 outputs a signal corresponding to the logic level of the temperature anomaly information signal CS1. When at least one of the logic levels of the selection data SD[SD1, SD2, SD3] input as the information selection signal SEL is L level, the AND circuit 334 does not output a signal corresponding to the logic level of the temperature anomaly information signal CS1 and sets the output terminal to high impedance. The AND circuit 334 also receives the temperature anomaly information signal CS2 output by the individual information output circuit 320 and is connected to one end of the resistor 336 at its output terminal. The other end of the resistor 336 is supplied with the ground potential.

[0153] The temperature information output circuit 330 in the liquid ejection device 1 and head unit 20 of the fourth embodiment configured as above outputs the signal from the output terminal of the AND circuit 334, which is the signal from one end of the resistor 336, as the temperature abnormality information signal CS.

[0154] Here, the temperature information output of the liquid ejection device 1 and the head unit 20 of the fourth embodiment is The following describes the relationship between the temperature abnormality information signal CS output by the circuit 330 and the information selection signal SEL output by the acquired information selection control circuit 340. Fig. 17 is a diagram for explaining the relationship between the temperature abnormality information signal CS output by the temperature information output circuit 330 of the fourth embodiment and the information selection signal SEL.

[0155] When the drive data signal DI1 requesting acquisition of information indicating whether the temperature of the drive signal selection circuit 200 included in print head 22-1 is normal is input to the acquired information selection circuit 300, the acquired information selection control circuit 340 generates selection data SD[SD1, SD2, SD3]=[0,0,1] as the information selection signal SEL and outputs it to the individual information output circuit 320 and the temperature information output circuit 330. When the selection data SD[SD1, SD2, SD3]=[0,0,1] is input, the AND circuit 334 in the temperature information output circuit 330 controls its output terminal to high impedance. At this time, the multiplexer 322 in the individual information output circuit 320 receives the same selection data SD[SD1, SD2, SD3]=[0,0,1] as the AND circuit 334. 17, the multiplexer 322 selects the temperature status signal XHOT1 corresponding to the temperature of the drive signal selection circuit 200 of the print head 22-1 and outputs it as the temperature abnormality information signal CS2. The temperature status signal XHOT1 output by the multiplexer 322 is supplied to the output terminal of the AND circuit 334 of the temperature information output circuit 330, causing the acquired information selection circuit 300 to output the temperature status signal XHOT1 corresponding to the temperature of the drive signal selection circuit 200 of the print head 22-1 as the temperature abnormality information signal CS.

[0156] Furthermore, when the acquired information selection circuit 300 receives a drive data signal DI1 requesting acquisition of information indicating whether the temperature of the drive signal selection circuit 200 included in print head 22-2 is normal, the acquired information selection control circuit 340 generates selection data SD[SD1, SD2, SD3]=[0,1,0] as the information selection signal SEL and outputs it to the individual information output circuit 320 and the temperature information output circuit 330. When the selection data SD[SD1, SD2, SD3]=[0,1,0] is received, the AND circuit 334 in the temperature information output circuit 330 controls its output terminal to high impedance. At this time, the multiplexer 322 in the individual information output circuit 320 receives the same selection data SD[SD1, SD2, SD3]=[0,1,0] as the AND circuit 334. 17, the multiplexer 322 selects the temperature status signal XHOT2 corresponding to the temperature of the drive signal selection circuit 200 of the print head 22-2 and outputs it as the temperature abnormality information signal CS2. The temperature status signal XHOT2 output by the multiplexer 322 is supplied to the output terminal of the AND circuit 334 of the temperature information output circuit 330, causing the acquired information selection circuit 300 to output the temperature status signal XHOT2 corresponding to the temperature of the drive signal selection circuit 200 of the print head 22-2 as the temperature abnormality information signal CS.

[0157] Furthermore, when the acquired information selection circuit 300 receives a drive data signal DI1 requesting acquisition of information indicating whether the temperature of the drive signal selection circuit 200 included in print head 22-3 is normal, the acquired information selection control circuit 340 generates selection data SD[SD1, SD2, SD3]=[0, 1, 1] as the information selection signal SEL and outputs it to the individual information output circuit 320 and the temperature information output circuit 330. When the selection data SD[SD1, SD2, SD3]=[0, 1, 1] is received, the AND circuit 334 in the temperature information output circuit 330 controls its output terminal to high impedance. At this time, the multiplexer 322 in the individual information output circuit 320 receives the same selection data SD[SD1, SD2, SD3]=[0, 1, 1] as the AND circuit 334. 17, the multiplexer 322 selects the temperature status signal XHOT3 corresponding to the temperature of the drive signal selection circuit 200 of the print head 22-3 and outputs it as the temperature abnormality information signal CS2. The temperature status signal XHOT3 output by the multiplexer 322 is supplied to the output terminal of the AND circuit 334 of the temperature information output circuit 330, and the acquired information selection circuit 300 , and outputs a temperature status signal XHOT3 corresponding to the temperature of the drive signal selection circuit 200 of the print head 22-3 as a temperature abnormality information signal CS.

[0158] Furthermore, when the acquired information selection circuit 300 receives a drive data signal DI1 requesting acquisition of information on whether the temperature of the drive signal selection circuit 200 included in print head 22-4 is normal, the acquired information selection control circuit 340 generates selection data SD[SD1, SD2, SD3]=[1, 0, 0] as the information selection signal SEL and outputs it to the individual information output circuit 320 and the temperature information output circuit 330. When the selection data SD[SD1, SD2, SD3]=[1, 0, 0] is input, the AND circuit 334 in the temperature information output circuit 330 controls its output terminal to high impedance. At this time, the multiplexer 322 in the individual information output circuit 320 receives the same selection data SD[SD1, SD2, SD3]=[1, 0, 0] as the AND circuit 334. 17, the multiplexer 322 selects the temperature status signal XHOT4 corresponding to the temperature of the drive signal selection circuit 200 of the print head 22-4 and outputs it as the temperature abnormality information signal CS2. The temperature status signal XHOT4 output by the multiplexer 322 is supplied to the output terminal of the AND circuit 334 of the temperature information output circuit 330, causing the acquired information selection circuit 300 to output the temperature status signal XHOT4 corresponding to the temperature of the drive signal selection circuit 200 of the print head 22-4 as the temperature abnormality information signal CS.

[0159] Furthermore, when the acquired information selection circuit 300 receives a drive data signal DI1 requesting acquisition of information indicating whether the temperature of the drive signal selection circuit 200 included in the print head 22-5 is normal, the acquired information selection control circuit 340 generates selection data SD[SD1, SD2, SD3]=[1, 0, 1] as the information selection signal SEL and outputs it to the individual information output circuit 320 and the temperature information output circuit 330. When the selection data SD[SD1, SD2, SD3]=[1, 0, 1] is input, the AND circuit 334 in the temperature information output circuit 330 controls its output terminal to high impedance. At this time, the multiplexer 322 in the individual information output circuit 320 receives the same selection data SD[SD1, SD2, SD3]=[1, 0, 1] as the AND circuit 334. 17, the multiplexer 322 selects the temperature status signal XHOT5 corresponding to the temperature of the drive signal selection circuit 200 of the print head 22-5 and outputs it as the temperature abnormality information signal CS2. The temperature status signal XHOT5 output by the multiplexer 322 is supplied to the output terminal of the AND circuit 334 of the temperature information output circuit 330, causing the acquired information selection circuit 300 to output the temperature status signal XHOT5 corresponding to the temperature of the drive signal selection circuit 200 of the print head 22-5 as the temperature abnormality information signal CS.

[0160] Furthermore, when the acquired information selection circuit 300 receives a drive data signal DI1 requesting acquisition of information on whether the temperature of the drive signal selection circuit 200 included in the print head 22-6 is normal, the acquired information selection control circuit 340 generates selection data SD[SD1, SD2, SD3]=[1,1,0] as the information selection signal SEL and outputs it to the individual information output circuit 320 and the temperature information output circuit 330. When the selection data SD[SD1, SD2, SD3]=[1,1,0] is input, the AND circuit 334 in the temperature information output circuit 330 controls its output terminal to high impedance. At this time, the multiplexer 322 in the individual information output circuit 320 receives the same selection data SD[SD1, SD2, SD3]=[1,1,0] as the AND circuit 334. 17, the multiplexer 322 selects the temperature status signal XHOT6 corresponding to the temperature of the drive signal selection circuit 200 of the print head 22-6 and outputs it as the temperature abnormality information signal CS2. The temperature status signal XHOT6 output by the multiplexer 322 is supplied to the output terminal of the AND circuit 334 of the temperature information output circuit 330, causing the acquired information selection circuit 300 to output the temperature status signal XHOT6 corresponding to the temperature of the drive signal selection circuit 200 of the print head 22-6 as the temperature abnormality information signal CS.

[0161] As described above, when the temperature information output circuit 330 outputs the temperature abnormality information signal CS2 as the temperature abnormality information signal CS, the information selection signal SEL output by the acquired information selection control circuit 340 selects one of the temperature state signals XHOT1 to XHOT6.

[0162] Furthermore, when a drive data signal DI1 requesting acquisition of information on whether all temperatures of the drive signal selection circuits 200 included in each of the print heads 22-1 to 22-6 are normal is input to the acquired information selection circuit 300, the acquired information selection control circuit 340 generates selection data SD[SD1, SD2, SD3]=[1,1,1] as the information selection signal SEL and outputs it to the individual information output circuit 320 and the temperature information output circuit 330. When selection data SD[SD1, SD2, SD3]=[1,1,1] is input, the AND circuit 334 of the temperature information output circuit 330 outputs a signal whose logic level changes in accordance with the temperature abnormality information signal CS1 output by the integrated information output circuit 310, and which is equivalent to the temperature abnormality information signal CS1. At this time, the integrated information output circuit 310 outputs a temperature abnormality information signal CS1 indicating whether or not all of the temperatures of the drive signal selection circuits 200 included in each of the print heads 22-1 to 22-6 of the head unit 20 are normal. As a result, the acquired information selection circuit 300 outputs the temperature abnormality information signal CS1 corresponding to the information indicating whether all of the temperatures of the drive signal selection circuits 200 included in each of the print heads 22-1 to 22-6 are normal as the temperature abnormality information signal CS.

[0163] Furthermore, the multiplexer 322 of the individual information output circuit 320 receives the same selection data SD[SD1, SD2, SD3]=[1,1,1] as the AND circuit 334. Therefore, as shown in FIG. 17, the multiplexer 322 does not select any of the temperature status signals XHOT1 to XHOT6 output by the print heads 22-1 to 22-6. At this time, the output terminal of the multiplexer 322 is controlled to a high impedance. That is, in the liquid ejection device 1 and head unit 20 of the fourth embodiment, the temperature information output circuit 330 outputs the temperature abnormality information signal CS1 as the temperature abnormality information signal CS when the information selection signal SEL does not select any of the temperature status signals XHOT1 to XHOT6.

[0164] The liquid ejection device 1 of the fourth embodiment configured as above also achieves the same effects as the liquid ejection device 1 and head unit 20 of the first embodiment described above.

[0165] Although the embodiments and modifications have been described above, the present invention is not limited to these embodiments and can be embodied in various forms without departing from the spirit of the present invention. For example, the above embodiments can be combined as appropriate.

[0166] The present invention includes configurations that are substantially the same as the configurations described in the embodiments (for example, configurations with the same function, method, and result, or configurations with the same purpose and effect). The present invention also includes configurations in which non-essential parts of the configurations described in the embodiments are replaced. The present invention also includes configurations that have the same effects as the configurations described in the embodiments or that can achieve the same purpose. The present invention also includes configurations in which publicly known technology is added to the configurations described in the embodiments.

[0167] The following can be derived from the above-described embodiment.

[0168] One aspect of the head unit is a plurality of ejection units including a first ejection unit that includes a first drive element and ejects liquid by driving the first drive element, and a second ejection unit that includes a second drive element and ejects liquid by driving the second drive element; a plurality of drive control circuits including a first drive control circuit that controls driving of the first drive element and a second drive control circuit that controls driving of the second drive element; a plurality of temperature detection circuits including a first temperature detection circuit that detects whether or not there is a temperature abnormality in the first drive control circuit and a second temperature detection circuit that detects whether or not there is a temperature abnormality in the second drive control circuit; an integrated information output circuit that outputs a first temperature abnormality information signal according to the plurality of detection results detected by the plurality of temperature detection circuits; an individual information output circuit that selects one of the plurality of detection results in response to a selection signal and outputs a second temperature abnormality information signal corresponding to the selected detection result; a temperature information output circuit that outputs the first temperature abnormality information signal, the second temperature abnormality information signal, and a temperature abnormality information signal in accordance with the selection signal; one temperature information output terminal for outputting a temperature information signal based on the temperature abnormality information signal; It has.

[0169] This head unit has an integrated information output circuit that outputs a first temperature abnormality information signal in accordance with multiple detection results detected by multiple temperature detection circuits, a temperature information output circuit that outputs a temperature abnormality information signal in accordance with the first temperature abnormality information signal, the second temperature abnormality information signal, and a selection signal, and a temperature information output circuit that outputs a temperature abnormality information signal in accordance with the first temperature abnormality information signal, the second temperature abnormality information signal, and the selection signal.Therefore, even when the head unit has multiple ejection units including a first ejection unit that includes a first drive element and ejects liquid by driving the first drive element, and a second ejection unit that includes a second drive element and ejects liquid by driving the second drive element, multiple drive control circuits including a first drive control circuit that controls driving of the first drive element, and a second drive control circuit that controls driving of the second drive element, and multiple temperature detection circuits including a first temperature detection circuit that detects whether or not there is a temperature abnormality in the first drive control circuit, and a second temperature detection circuit that detects whether or not there is a temperature abnormality in the second drive control circuit, a temperature information signal based on the temperature abnormality information signal can be output from a single temperature information output terminal. This makes it possible to individually acquire temperature abnormalities for multiple print heads without increasing the number of wiring and terminals, even if the head unit has multiple ejection sections provided in different print heads.

[0170] In one aspect of the head unit, The integrated information output circuit If all of the plurality of detection results indicate normal, outputting the first temperature abnormality information signal including normal information; When at least one of the plurality of detection results indicates an abnormality, the first temperature abnormality information signal including information about the abnormality may be output.

[0171] In this head unit, the integrated information output circuit can integrate and obtain and determine in a short time the presence or absence of temperature abnormalities detected by multiple temperature detection circuits, including a first temperature detection circuit that detects the presence or absence of temperature abnormalities in the first drive control circuit and a second temperature detection circuit that detects the presence or absence of temperature abnormalities in the second drive control circuit.

[0172] In one aspect of the head unit, The individual information output circuit If the selected detection result indicates normal, outputting the second temperature abnormality information signal including normal information regardless of the non-selected detection result that was not selected from the plurality of detection results in response to the selection signal; If the selected detection result indicates an abnormality, the second temperature abnormality information signal including information about the abnormality may be output regardless of the non-selected detection result.

[0173] In this head unit, the individual information output circuit can individually acquire and determine the presence or absence of temperature abnormalities detected by a plurality of temperature detection circuits, including a first temperature detection circuit that detects the presence or absence of temperature abnormalities in the first drive control circuit and a second temperature detection circuit that detects the presence or absence of temperature abnormalities in the second drive control circuit. The presence or absence of a temperature abnormality in each of the plurality of drive control circuits can be individually acquired, including the presence or absence of a temperature abnormality in the second drive control circuit that controls the driving of the second drive element.

[0174] In one aspect of the head unit, the individual information output circuit includes a plurality of input terminals including a first input terminal to which the detection result of the first temperature detection circuit is input and a second input terminal to which the detection result of the second temperature detection circuit is input, and a selection information output terminal that outputs the second temperature abnormality information signal; When the detection result of the first temperature detection circuit is selected as the selected detection result, the first input terminal and the selected information output terminal may be electrically connected, and the input terminals of the plurality of input terminals other than the first input terminal may be electrically disconnected from the selected information output terminal.

[0175] In this head unit, the risk that a signal input to an input terminal that is not selected as a selective detection result will contribute to the detection result of the first temperature detection circuit that is selected as a selective detection result is reduced.

[0176] In one aspect of the head unit, The individual information output circuit may be a multiplexer that selects one of the plurality of detection results in response to the selection signal.

[0177] This head unit does not require complicated circuits and can be made smaller.

[0178] In one aspect of the head unit, The individual information output circuit may electrically disconnect the input terminals from the selected information output terminal when the selection signal does not select any of the plurality of detection results.

[0179] In this head unit, the risk of malfunction occurring when disturbance noise or the like is superimposed on the selection signal is reduced.

[0180] In one aspect of the head unit, The individual information output circuit may output a signal of a predetermined voltage value as the second temperature abnormality information signal when the selection signal does not select any of the plurality of detection results.

[0181] In this head unit, the risk of malfunction occurring when disturbance noise or the like is superimposed on the selection signal is reduced.

[0182] In one aspect of the head unit, The first temperature detection circuit outputs a first state signal that goes to a low level when it detects a temperature abnormality of the first drive control circuit as a result of detecting whether or not there is a temperature abnormality in the first drive control circuit, and goes to a high level when it does not detect a temperature abnormality in the first drive control circuit, and the second temperature detection circuit outputs a second state signal that goes to a low level when it detects a temperature abnormality of the second drive control circuit as a result of detecting whether or not there is a temperature abnormality in the second drive control circuit, and goes to a high level when it does not detect a temperature abnormality in the second drive control circuit, The integrated information output circuit may include an AND circuit or a circuit equivalent to an AND circuit to which the first status signal and the second status signal are input.

[0183] This head unit does not require complicated circuits and can be made smaller.

[0184] In one aspect of the head unit, The first temperature detection circuit outputs a first state signal that goes to a high level when it detects a temperature abnormality of the first drive control circuit as a result of detecting whether or not there is a temperature abnormality in the first drive control circuit, and goes to a low level when it does not detect a temperature abnormality in the first drive control circuit, and the second temperature detection circuit outputs a second state signal that goes to a high level when it detects a temperature abnormality in the second drive control circuit as a result of detecting whether or not there is a temperature abnormality in the second drive control circuit, and goes to a low level when it does not detect a temperature abnormality in the second drive control circuit, The integrated information output circuit may include an OR circuit or a circuit equivalent to an OR circuit to which the first status signal and the second status signal are input.

[0185] This head unit does not require complicated circuits and can be made smaller.

[0186] In one aspect of the head unit, The temperature information output circuit may output the first temperature abnormality information signal as the temperature abnormality information signal when the selection signal does not select any of the plurality of detection results.

[0187] In one aspect of the head unit, The temperature information output circuit may select the first temperature abnormality information signal or the second temperature abnormality information signal in response to the selection signal, and output the selected signal as the temperature abnormality information signal.

[0188] In one aspect of the head unit, When the temperature information output circuit outputs the second temperature abnormality information signal as the temperature abnormality information signal, the selection signal selects one of the plurality of detection results, When the temperature information output circuit outputs the first temperature abnormality information signal as the temperature abnormality information signal, the selection signal may not select any of the plurality of detection results.

[0189] In one aspect of the head unit, When the first temperature abnormality information signal includes information about an abnormality, the device may further include an abnormality location identifying circuit that identifies an abnormal location from among the plurality of drive control circuits based on the second temperature abnormality information signal.

[0190] In this head unit, it is possible to efficiently identify a plurality of drive control circuits in which an abnormality has occurred. [Explanation of symbols]

[0191] 1...liquid ejection device, 2...ink container, 10...control unit, 15...cable, 20...head unit, 21...carriage, 22...print head, 30...movement unit, 31...carriage motor, 32...endless belt, 40...transport unit, 41...transport motor, 42...transport roller, 50...drive circuit, 52...reference voltage output circuit, 60...piezoelectric element, 100...control circuit, 200...drive signal selection circuit, 210...selection control circuit, 212...shift register, 214...latch circuit, 216...decoder, 230...selection circuit, 232...inverter, 234...transfer gate, 300...acquired information selection circuit, 310...integration Combined information output circuit, 312...AND circuit, 314...OR circuit, 320...individual information output circuit, 322...multiplexer, 330...temperature information output circuit, 332...multiplexer, 334...AND circuit, 336...resistor, 340...acquired information selection control circuit, 400...temperature abnormality detection circuit, 410...resistor, 420...diode, 430...reference voltage generation circuit, 440...comparator, 450...resistor, 460...transistor, 600...ejection portion, 601...piezoelectric element, 611, 612...electrodes, 621...diaphragm, 631...cavity, 632...nozzle plate, 641...reservoir, 651...nozzle, 661...ink supply port, P...medium

Claims

1. a plurality of ejection units including a first ejection unit including a first drive element and ejecting liquid by driving the first drive element, and a second ejection unit including a second drive element and ejecting liquid by driving the second drive element; a plurality of drive control circuits including a first drive control circuit that controls driving of the first drive element and a second drive control circuit that controls driving of the second drive element; a plurality of temperature detection circuits including a first temperature detection circuit that detects whether or not there is a temperature abnormality in the first drive control circuit and a second temperature detection circuit that detects whether or not there is a temperature abnormality in the second drive control circuit; an integrated information output circuit that outputs a first temperature abnormality information signal in accordance with a plurality of detection results detected by the plurality of temperature detection circuits; an individual information output circuit that selects one of the plurality of detection results in response to a selection signal and outputs a second temperature abnormality information signal corresponding to the selected detection result; a temperature information output circuit that outputs the first temperature abnormality information signal, the second temperature abnormality information signal, and a temperature abnormality information signal in accordance with the selection signal; one temperature information output terminal for outputting a temperature information signal based on the temperature abnormality information signal; having A head unit characterized by:

2. The integrated information output circuit If all of the plurality of detection results indicate normal, outputting the first temperature abnormality information signal including normal information; When at least one of the plurality of detection results indicates an abnormality, the first temperature abnormality information signal including information on the abnormality is output.

2. The head unit according to claim 1.

3. The individual information output circuit If the selected detection result indicates normal, outputting the second temperature abnormality information signal including normal information regardless of the non-selected detection result that was not selected from the plurality of detection results in response to the selection signal; When the selected detection result indicates an abnormality, the second temperature abnormality information signal including information on the abnormality is output regardless of the non-selected detection result.

2. The head unit according to claim 1.

4. the individual information output circuit includes a plurality of input terminals including a first input terminal to which the detection result of the first temperature detection circuit is input and a second input terminal to which the detection result of the second temperature detection circuit is input, and a selection information output terminal that outputs the second temperature abnormality information signal, when the detection result of the first temperature detection circuit is selected as the selected detection result, the first input terminal is electrically connected to the selected information output terminal, and the input terminals of the plurality of input terminals other than the first input terminal are electrically disconnected from the selected information output terminal.

2. The head unit according to claim 1.

5. the individual information output circuit is a multiplexer that selects one of the plurality of detection results in response to the selection signal.

5. The head unit according to claim 4.

6. the individual information output circuit electrically disconnects the plurality of input terminals from the selection information output terminal when the selection signal does not select any of the plurality of detection results; 6. The head unit according to claim 4 or 5.

7. the individual information output circuit outputs a signal of a predetermined voltage value as the second temperature abnormality information signal when the selection signal does not select any of the plurality of detection results.

7. The head unit according to claim 6.

8. The first temperature detection circuit outputs a first state signal that goes to a low level when it detects a temperature abnormality of the first drive control circuit as a result of detecting whether or not there is a temperature abnormality in the first drive control circuit, and goes to a high level when it does not detect a temperature abnormality in the first drive control circuit, and the second temperature detection circuit outputs a second state signal that goes to a low level when it detects a temperature abnormality in the second drive control circuit as a result of detecting whether or not there is a temperature abnormality in the second drive control circuit, and goes to a high level when it does not detect a temperature abnormality in the second drive control circuit, the integrated information output circuit includes an AND circuit or a circuit equivalent to an AND circuit to which the first status signal and the second status signal are input.

2. The head unit according to claim 1.

9. The first temperature detection circuit outputs a first state signal that goes to a high level when it detects a temperature abnormality in the first drive control circuit as a result of detecting whether or not there is a temperature abnormality in the first drive control circuit, and goes to a low level when it does not detect a temperature abnormality in the first drive control circuit, and the second temperature detection circuit outputs a second state signal that goes to a high level when it detects a temperature abnormality in the second drive control circuit as a result of detecting whether or not there is a temperature abnormality in the second drive control circuit, and goes to a low level when it does not detect a temperature abnormality in the second drive control circuit, the integrated information output circuit is configured to include an OR circuit or a circuit equivalent to an OR circuit to which the first status signal and the second status signal are input.

2. The head unit according to claim 1.

10. the temperature information output circuit outputs the first temperature abnormality information signal as the temperature abnormality information signal when the selection signal does not select any of the plurality of detection results.

2. The head unit according to claim 1.

11. the temperature information output circuit selects the first temperature abnormality information signal or the second temperature abnormality information signal in response to the selection signal, and outputs the selected signal as the temperature abnormality information signal.

2. The head unit according to claim 1.

12. When the temperature information output circuit outputs the second temperature abnormality information signal as the temperature abnormality information signal, the selection signal selects one of the plurality of detection results, When the temperature information output circuit outputs the first temperature abnormality information signal as the temperature abnormality information signal, the selection signal does not select any of the plurality of detection results.

12. The head unit according to claim 11.

13. an abnormality location identifying circuit that identifies an abnormal location from among the plurality of drive control circuits based on the second temperature abnormality information signal when the first temperature abnormality information signal includes information of an abnormality; 13. The head unit according to claim 1, wherein the first and second electrodes are arranged parallel to each other.

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