Element substrate and recording device

Abstract

To reduce an influence of noise on a temperature detection element.SOLUTION: An element substrate comprises: a first heat generation element for generating thermal energy, by supply of power, which discharges liquid; a first temperature detection element for detecting a temperature of the first heat generation element; a second temperature detection element for detecting a temperature of the first heat generation element; a first output circuit for electrifying the first temperature detection element and outputting, as temperature information, a voltage of one terminal of the first temperature detection element; and a second output circuit for electrifying the second temperature detection element and outputting, as temperature information, a voltage of one terminal of the second temperature detection element. The other terminal of the first temperature detection element and the other terminal of the second temperature detection element are connected to a common wiring that is maintained at a predetermined potential.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an element substrate and a recording apparatus. [Background technology]

[0002] Mechanisms using heating elements are known as ejection mechanisms for liquids such as ink. The heating elements are arranged on an element substrate and form nozzles that eject liquid. Droplets of ink or other liquid are ejected from the nozzles toward a recording medium by thermal energy generated by passing an electric current through the heating elements. By applying such an ejection mechanism to a recording device, an image can be formed on the recording medium. Patent Document 1 discloses a technique for determining the state (normal, defective) of a nozzle by monitoring the temperature of the heating elements. In monitoring the temperature, two temperature detection elements are used for one heating element, and the state of the nozzle is determined from the detection results of these. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6388372 Summary of the Invention [Problem to be solved by the invention]

[0004] The temperature detection element may be affected by noise from surrounding circuits and wiring.

[0005] The present invention provides a technique capable of reducing the effect of noise on a temperature detection element. [Means for solving the problem]

[0006] According to the present invention, a first heating element that generates thermal energy for discharging liquid when power is supplied thereto; a first temperature detection element for detecting a temperature of the first heating element; a second temperature detection element for detecting a temperature of the first heating element; a first output circuit that energizes the first temperature detection element to output a voltage at one terminal of the first temperature detection element as temperature information; and a second output circuit that energizes the second temperature detection element to output a voltage at one terminal of the second temperature detection element as temperature information, the other terminal of the first temperature detection element and the other terminal of the second temperature detection element are connected to a common wiring that is maintained at a predetermined potential. The present invention provides a device substrate comprising: Effect of the Invention

[0007] According to the present invention, it is possible to provide a technique capable of reducing the effect of noise on a temperature detection element. [Brief description of the drawings]

[0008] [Figure 1] 1 is an external view of a recording apparatus according to an embodiment of the present invention. [Diagram 2] FIG. [Diagram 3] FIG. 2 is a plan view showing the arrangement of main components of an element substrate according to an embodiment of the present invention. [Figure 4] 3. (A) is a cross-sectional view taken along line AA in FIG. 3, and (B) is a cross-sectional view taken along line BB in FIG. [Diagram 5] FIG. [Figure 6] 4A to 4C are explanatory diagrams of a part of the circuit of the element substrate. [Figure 7] 4 is a timing chart of signals input to an element substrate. [Figure 8] 13A and 13B are diagrams showing other examples of the arrangement of temperature detection elements. [Figure 9] FIG. 13 is a diagram showing another example of the arrangement of temperature detection elements. [Figure 10] FIG. 10 is a circuit diagram of an element substrate in the example of FIG. 9 . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, the embodiments will be described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe a number of features, not all of these features are essential to the invention, and the features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0010] First Embodiment FIG. 1 is an external view of a recording device 10 according to an embodiment of the present invention. The recording device 10 is an inkjet recording device that ejects ink to record on a recording medium. Note that "recording" does not only include forming meaningful information such as characters and figures, but also includes forming an image, design, pattern, etc. on a recording medium, regardless of whether it is meaningful or not, or processing the medium, regardless of whether it is manifested in a way that can be visually perceived by humans. In addition, although a sheet of paper is assumed as the "recording medium" in this embodiment, it may also be cloth, plastic film, etc.

[0011] In addition, the recording device to which the present invention can be applied is not limited to an inkjet recording device, and can also be applied to, for example, a thermal transfer type recording device such as a melting type or a dye sublimation type. The recording device may also be, for example, a manufacturing device for manufacturing a color filter, an electronic device, an optical device, a microstructure, etc. by a predetermined recording method. The recording device may also be a device that forms a three-dimensional image from 3D data.

[0012] The recording device 10 includes an ink tank 11 and a recording head 12, which are assembled into one unit and are mounted on a carriage 14. The recording head 12 ejects liquid (ink) contained in the ink tank 11 onto a recording medium P to perform recording. The carriage 14 can be reciprocated in the direction of the arrow by a drive unit 15. The drive unit 15 includes a lead screw 15a and a guide shaft 15b that extend in the moving direction of the carriage 14. The lead screw 15a engages with a screw hole (not shown) of the carriage 14, and the carriage 14 moves due to its rotation. A motor 15c and a gear train 15d are a rotation mechanism for the lead screw 15a. The guide shaft 15b guides the movement of the carriage 14. An optical sensor 14b that detects the detected piece 14a of the carriage 14 is disposed at one end of the moving range of the carriage 14, and the detection result is used to control the movement of the carriage 14.

[0013] The transport unit 13 transports the recording medium P. The transport unit 13 includes a motor (not shown) that is a drive source, and a transport roller (not shown) that rotates by the driving force of the motor, and the recording medium P is transported by the rotation of the transport roller.

[0014] The recording device 10 includes an internal power source 16 that supplies power consumed by the recording device 10, and a control circuit 17 that controls the recording device 10. The control circuit 17 records an image on the recording medium P by alternately moving the recording head 12 and ejecting ink by moving the carriage 14, and transporting the recording medium P.

[0015] 2 is a perspective view of the ink tank 11 and the recording head 12 which are made into one unit. The ink tank 11 and the recording head 12 can be separated at the position indicated by the dashed line. The recording head 12 has a plurality of ejection ports 116 which form nozzles for ejecting ink. The recording head 12 has a laminate of an element substrate and a nozzle member.

[0016] <Element substrate and nozzle member> Fig. 3 is a plan view (viewed in the normal direction of the substrate) showing the main components of the element substrate 1 that constitutes the recording head 12, and shows the structure related to one ejection port 116. Fig. 4(A) and Fig. 4(B) are cross-sectional views taken along lines AA and BB in Fig. 3, and also show a nozzle member 118 laminated on the element substrate 1.

[0017] The element substrate 1 includes a substrate 100 made of, for example, single crystal silicon, and an insulating layer 101 is formed on the substrate 100. The insulating layer 101 is made of an inorganic material, for example, silicon oxide, and has electrical insulation properties, electrically isolating each of the wirings formed in the insulating layer 101. Note that transistors and multi-layer wiring (not shown) are disposed on the substrate 100.

[0018] A heating element (heating resistor element) 103 is disposed on the insulating layer 101, and a protective film 106 is laminated on the insulating layer 101 and the heating element 103. Furthermore, an anti-cavitation layer 107 is laminated on the protective film 106. The anti-cavitation layer 107 serves to provide resistance to cavitation, which cushions the impact of pressure waves generated when bubbles disappear after liquid is discharged from the discharge port 116, and to provide resistance to electrochemical corrosion caused by the liquid.

[0019] The heating element 103 is an electro-thermal conversion element that generates thermal energy for ejecting liquid (ink) from the ejection port 116 when power is supplied to the heating element 103. The heating element 103 is made of a resistance material such as tantalum silicon nitride or tungsten silicon nitride. The protective film 106 is made of an inorganic material such as silicon nitride. The cavitation-resistant layer 107 is made of a metal material such as tantalum or iridium.

[0020] The heating element 103 of this embodiment is a thin-film resistor formed in a strip shape and has a rectangular shape in a plan view. One end of the heating element 103 in the longitudinal direction is connected to a signal wiring 108 in a lower layer via a conductive plug 104, and the other end of the heating element 103 in the longitudinal direction is connected to a signal wiring 109 in a lower layer via a conductive plug 105. As shown in FIG. 5 described later, the signal wiring 108 is a power line connected to a power supply (VH), and the signal wiring 109 is a ground line grounded (GNDH) via a switch element 216 (see FIG. 5) described later.

[0021] In the insulating layer 101, the temperature detection element 110 and the temperature detection element 113 are disposed below the heating element 103. In other words, an insulating material is interposed between the heating element 103 and the temperature detection elements 110 and 113. In the case of this embodiment, the temperature detection elements 110 and 113 are both thin-film resistors whose resistance value is temperature dependent. The temperature detection elements 110 and 113 may be formed of a material with a large resistance temperature coefficient. For example, the temperature detection elements 110 and 113 are formed of a single layer or a multilayer of metal materials or alloys such as iridium, tantalum, titanium, tungsten, silicon, tantalum silicon nitride, and tungsten silicon nitride.

[0022] In this embodiment, the temperature detection elements 110 and 113 are designed to have the same room temperature resistance value. In order to increase the output voltage of the temperature detection elements 110 and 113, the temperature detection elements 110 and 113 may be made of a material with a high temperature resistance coefficient and have a resistivity equivalent to that of the heating element 103.

[0023] In this embodiment, the configurations of the temperature detection elements 110 and 113 are designed so that the thermal sensitivity of the temperature detection element 110 and the thermal sensitivity of the temperature detection element 113 differ with respect to the heating element 103. Thermal sensitivity is the ease with which temperature is transmitted from the heating element 103 to the temperature detection elements 110 and 113. This results in a difference in the magnitude of the signals output from the temperature detection elements 110 and 113 for the same heat source (heating element 103). By taking the difference in the magnitude of these signals, the nozzle condition can be determined with greater accuracy.

[0024] As a specific embodiment of the temperature detection elements 110 and 113, the arrangement and shape are different. The temperature detection elements 110 and 113 are arranged so as to be asymmetrical with respect to the heating element 103 in a plan view. In this embodiment, the temperature detection element 110 and the temperature detection element 113 have different shortest distances to the center part CT of the heating element 103. The temperature detection element 110 crosses the heating element 103 in the width direction, and the temperature detection element 113 does not cross the heating element 103 in the width direction. The temperature detection element 110 overlaps with the center part CT in a plan view, and the shortest distance is 0. The temperature detection element 113 is arranged at a position where it does not overlap with the heating element 103 in a plan view, and the shortest distance to the center part CT is longer than that of the temperature detection element 110. The temperature detection element 113 is arranged at a position farther away from the heating element 103 than the temperature detection element 110. With such an embodiment, the temperature detection element 110 and the temperature detection element 113 can obtain different thermal sensitivities.

[0025] The temperature detection element 110 is connected to a predetermined wiring via conductive plugs 111 and 112, and the temperature detection element 113 is connected to a predetermined wiring via conductive plugs 114 and 115. Specifically, the temperature detection element 110 is connected to a lower layer pad 120 via conductive plug 112, and is further connected to a lower layer signal wiring 124 via conductive plug 122. The temperature detection element 113 is connected to a lower layer pad 119 via conductive plug 114, and is further connected to a lower layer signal wiring 123 via conductive plug 121.

[0026] Heat dissipation wiring 127 is arranged below heat generating element 103, and heat dissipation wiring 127 is connected to heat dissipation wiring 128 in a lower layer via plug 125, and heat dissipation wiring 128 is connected to substrate 100 via plug 126. With this configuration, heat generated by heat generating element 103 is dissipated to substrate 100 via the plug.

[0027] The conductive plugs 104, 105, 112, 114, 121, 122, 125, and 126 are made of a metal material mainly composed of, for example, tungsten or copper. The signal wirings 108, 109, 123, and 124 and the heat dissipation wirings 127 and 128 are made of a metal material mainly composed of, for example, aluminum or copper.

[0028] The nozzle member 118 forms an ejection port 116 and a bubbling chamber 117. The bubbling chamber 117 is an area that contributes to ejecting ink, and has an area larger than that of the heat generating element 103 in a plan view. An ink supply port 118 and an ink discharge port 119 are formed in the bubbling chamber 117.

[0029] <Circuit on element substrate> Fig. 5 shows an example of the configuration of a circuit mounted on the element substrate 1. The element substrate 1 includes a nozzle array circuit 201 and a determination circuit 219. In the example of Fig. 5, for ease of explanation, a configuration in which the nozzle array circuit 201 includes four heat elements 103 (an example in which there are four nozzles) is illustrated. Therefore, the circuit of Fig. 5 includes control circuits 202a to 202d (collectively referred to as control circuits 202) provided for each of the four heat elements 103.

[0030] Each control circuit 202 includes drive circuits 214a-214d that drive the four heat elements 103 individually, and output circuits 213a-213d that control the temperature detection operation of the four sets of temperature detection elements 110 and 113. The drive circuits 214a-214d are collectively referred to as drive circuits 214. The output circuits 213a-213d are collectively referred to as drive circuits 213. Each output circuit 213 selects the temperature detection elements 110 and 113 that perform the detection operation (energizing the temperature detection elements) and outputs temperature information (voltage generated by the temperature detection elements) that is the detection result. The nozzle array circuit 201 also includes a constant current circuit 204, and buffer circuits (voltage followers) 217 ​​and 218.

[0031] The element substrate 1 has an input section to which a signal is input from the outside (internal power supply 16 and control circuit 17) and an output section to which a signal is output to the outside (collectively referred to as an input / output section). The input / output section is composed of pads or terminals. As part of the input / output section, VHTA receives a voltage (driving power for the temperature detection elements 110 and 113) supplied to the constant current circuit 204. VSS is the reference potential (ground) of the element substrate 1. VH is the voltage used to drive the heating resistor element 103, and GNDH is the reference potential (ground) of the element substrate 1.

[0032] The drive circuit 214 that drives the heating element 103 includes a switch element (MOS transistor) 216 and an AND gate circuit 215. The AND gate 215 has two input terminals, one of which receives the HE signal and the other of which receives the mask signals Seg_sel1 to Seg_sel4. The output of the AND gate 215 is connected to the gate terminal of the switch element (MOS transistor) 216. One terminal of the heating element 103 is connected to the wiring 108 that is connected to VH, and the other terminal is connected to the GNDH wiring via the switch element 216.

[0033] The HE signal is a signal that determines the ON or OFF state of the switch element 216. The mask signals Seg_sel1 to 4 are signals that mask the HE signal. When driving the heating element 103 of the control circuit 202a, the mask signal Seg_sel1 is selected and set to H level. This unmasks the HE signal, and the AND gate 215 outputs a signal H1 to the gate terminal of the switch element 216. When an H level signal is input as the H1 signal to the gate terminal of the switch element 216, the heating element 103 has a VH (e.g., 24 V) voltage applied to one terminal and a GNDH voltage applied to the other terminal, and this power supply generates thermal energy that ejects liquid (ink).

[0034] Similarly, when driving the heating element 103 of the control circuit 202b, the mask signal Seg_sel2 is selected and set to H level. When a high-level signal is input as the H2 signal to the gate terminal of the switch element 216, the heating element 103 generates thermal energy for discharging liquid. When driving the heating element 103 of the control circuit 202c, the mask signal Seg_sel3 is selected and set to H level. When a high-level signal is input as the H3 signal to the gate terminal of the switch element 216, the heating element 103 generates thermal energy for discharging liquid. When driving the heating element 103 of the control circuit 202d, the mask signal Seg_sel4 is selected and set to H level. When a high-level signal is input as the H4 signal to the gate terminal of the switch element 216, the heating element 103 generates thermal energy for discharging liquid.

[0035] Although it is possible to select multiple signals Seg_sel1 to 4 at the same time, only one of them is selected when inspecting the state of the nozzles using the temperature detection elements 110 and 113. This makes it possible to reduce the influence of noise from the circuits of other nozzles.

[0036] The output circuit 213 includes switch elements (MOS transistors) 209 to 212. The switch element 209 and the switch 210 are connected in series. A terminal of the switch element 210 is connected to the + side of the buffer circuit 217, and temperature information is input to the buffer circuit 217. One terminal of the temperature detection element 110 is connected to a wiring that connects the switch elements 209 and 210, and the other terminal is connected to a wiring 124 connected to VSS. The switch element 211 and the switch 212 are connected in series. A terminal of the switch 212 is connected to the + side of the buffer circuit 218, and temperature information is input to the buffer circuit 218. One terminal of the temperature detection element 113 is connected to a wiring that connects the switch elements 211 and 212, and the other terminal is connected to a wiring 124 connected to VSS.

[0037] The constant current circuit 204 includes two current supply circuits 207 and 208, a current type DA converter (DAC) 205, and a mirroring circuit 206. One terminal of the mirroring circuit 206 is connected to VHTA, and the other terminal is connected in series to the DAC 205. The other terminal of the DAC 205 is connected to VSS. One terminal of the current supply circuit 207 is connected to the VHTA wiring, and the other terminal is connected to a switch element 209. One terminal of the current supply circuit 208 is connected to VHTA, and the other terminal is connected to a switch element 211. The mirroring circuit 206 and the current supply circuits 207 and 208 are connected at their gates.

[0038] The current supply circuits 207 and 208 form a current mirror circuit. The constant current circuit 204 mirrors the current Iref to the current supply circuits 207 and 208 with a current type DAC 205 as a reference current source and a mirroring circuit 206 at an n-fold amplification factor (n=real number). As a power supply source to the constant current circuit 204, a VHTA voltage (for example, 5V) is applied to one terminal of the constant current circuit 204 from the outside, and a VSS voltage is applied to the other terminal. The switch element 209 controls the current supply of the current supply circuit 207 to the temperature detection element 110. The switch element 210 controls the output of the voltage generated in the temperature detection element 110 to the buffer circuit 217. Similarly, the switch element 211 controls the current supply of the current supply circuit 208 to the temperature detection element 113. The switch element 212 controls the output of the voltage generated in the temperature detection element 113 to the buffer circuit 218.

[0039] The selection signals S1 to S4 are input to the gate terminals of the switch elements 209 to 212. The selection signals S1 to S4 are signals for selecting a pair of temperature detection elements 110 and 113 that are to be subjected to a temperature detection operation.

[0040] Signal S1 is a signal for selecting a pair of temperature detection elements 110 and 113 in output circuit 213a. By setting signal S1 to H level, switch elements 209 to 212 in output circuit 213a are simultaneously turned on, and temperature detection elements 110 and 113 in output circuit 213a are selected. Currents are applied to temperature detection elements 110 and 113 from current supply circuits 207 and 208, and temperature information V1 and V2 are output from switch elements 210 and 212 to buffer circuits 217 and 218.

[0041] Similarly, signal S2 is a signal for selecting a pair of temperature detection elements 110 and 113 in output circuit 213b. By setting signal S2 to H level, switch elements 209 to 212 in output circuit 213b are simultaneously turned on. Currents are applied from current supply circuits 207 and 208 to temperature detection elements 110 and 113 in output circuit 213b, and temperature information V1 and V2 are output from switch elements 210 and 212 to buffer circuits 217 and 218. Signal S3 is a signal for selecting a pair of temperature detection elements 110 and 113 in output circuit 213c. By setting signal S3 to H level, switch elements 209 to 212 in output circuit 213c are simultaneously turned on. A current is applied from the current supply circuits 207 and 208 to the temperature detection elements 110 and 113 of the output circuit 213c, and temperature information V1 and V2 are output from the switch elements 210 and 212 to the buffer circuits 217 and 218. A signal S4 is a signal for selecting a pair of the temperature detection elements 110 and 113 of the output circuit 213d. By setting the signal S4 to H level, the switch elements 209 to 212 of the output circuit 213d are simultaneously turned on. A current is applied from the current supply circuits 207 and 208 to the temperature detection elements 110 and 113 of the output circuit 213d, and temperature information V1 and V2 are output from the switch elements 210 and 212 to the buffer circuits 217 and 218.

[0042] When inspecting the state of the nozzles, the signals S1 to S4 are sequentially set to H level so that multiple signals do not become H level at the same time.

[0043] In the temperature detection elements 110 and 113, when the room temperature is T0, the resistance at that time is Rs0, and the temperature coefficient of resistance of the temperature detection element 110 is TCR, the resistance Rs1 of the temperature detection element 110 at temperature T1 is expressed by the following equation (1).

[0044] Rs1 = Rs0 {1 + TCR (T1 - T0)} (1) The voltage (temperature information) V1 generated at the constant current supply side terminal of the temperature detection element 110 is expressed by the following equation (2).

[0045] V1=Iref·Rs1=Iref·Rs0·{1+TCR·(T1-T0)} (2) The temperature information V 1 expressed by the above equation (2) is output to the buffer circuit 217 .

[0046] The resistance Rs2 of the temperature detection element 113 at the temperature T2 is expressed by the following equation (3).

[0047] Rs2 = Rs0 {1 + TCR (T2 - T0)} (3) The voltage (temperature information) V2 generated at the constant current supply side terminal of the temperature detection element 113 is expressed by the following equation (4).

[0048] V2=Iref·Rs2=Iref·Rs0·{1+TCR·(T2-T0)} (4) The temperature information V2 expressed by the above formula (4) is output to the buffer circuit 218 through the wiring V2.

[0049] In this embodiment, the temperature detection elements 110 and 113 are configured to have the same room temperature resistance Rs0, but the room temperature resistances may be different. In that case, the constant current value supplied to the temperature detection elements 110 and 113 may be adjusted by the current supply circuits 207 and 208 so that the temperature information V1 and V2 at room temperature T0 are equal.

[0050] Next, in this embodiment, the temperature information V1, V2 is input to the judgment circuit 219 via the buffer circuits 217, 218. If the temperature information is input to the differential amplifier 220 in the judgment circuit 219 without passing through the buffer circuits 217 and 218, the resistance of the switch element may affect the input impedance of the differential amplifier 220. As a result, the temperature information V1, V2 is input to the differential amplifier 220 with a voltage drop. For this reason, in this embodiment, the temperature information V1, V2 is input to the differential amplifier 220 as temperature information Vs1, Vs2 via the buffer circuits 217, 218.

[0051] The determination circuit 219 includes a differential amplifier 220, a low-pass filter 221, a voltage output type DA converter (DAC) 222, and a comparator 223. The differential amplifier 220 has two input terminals, one of which is connected to the output terminal of the buffer circuit 217, and the other of which is connected to the output terminal of the buffer circuit 218.

[0052] The output terminal of the differential amplifier 220 is connected to the input terminal of the low-pass filter 221. An external threshold signal Dth is input to the input terminal of the voltage output type DAC 222. The comparator 223 has two input terminals, one of which is connected to the output terminal of the low-pass filter 221 and the other of which is connected to the output terminal of the voltage output type DAC 222. The output of the comparator 223 is output to the outside (for example, the control circuit 17) via RSLT.

[0053] 6A is a circuit diagram showing a detailed circuit configuration of the differential amplifier 220. The differential amplifier 220 includes an operational amplifier 301, a constant voltage source 302, and resistors 303 to 306. The operational amplifier 301 has two input terminals, one of which is connected to one terminal of a resistor 303 and a resistor 305, and the other of which is connected to one terminal of a resistor 304 and a resistor 306. The other terminal of the resistor 305 is connected to the output terminal of the operational amplifier 301. The other terminal of the resistor 306 is connected to VSS via the constant voltage source 302.

[0054] The differential amplifier 220 amplifies the signal obtained by subtracting the temperature information Vs1 from the temperature information Vs2 with an amplification factor Gdif, and outputs a signal Vdif that is offset by the voltage Vofs of the constant voltage source 302 and is expressed by the following equation (5).

[0055] Vdif = Gdif (Vs2 - Vs1) + Vofs =Vofs-Gdif·Iref·Rs0·TCR·(T2-T1) (5) Here, if the resistance value of each of the resistors 303 and 304 is RD1, and the resistance value of each of the resistors 305 and 306 is RD2, the amplification factor Gdif is Gdif=RD2 / RD1 (6) It is expressed as:

[0056] Please refer to FIG. 5. When Vs1 and Vs2 are viewed individually, there is an effect of noise. By subtracting Vs1 from Vs2, the above noise can be reduced. This is also an advantage of associating two temperature detection elements 110 and 113 with one heating element 103. Furthermore, noise remaining in the signal Vdif is suppressed by the low-pass filter 221 and is output as the signal VF.

[0057] The voltage output type DAC 222 converts the input threshold signal Dth into a threshold voltage Vdth and outputs it. For example, Vdth can be set in 256 ranks from 0.5V to 2.54V in increments of 8mV. A comparator 223 judges the state of the nozzle by comparing the signal VF with a threshold voltage Vdth based on the threshold signal Dth. If VF>Vdth, the comparator 223 outputs a signal CMP that is high level (non-ejection state), and if VF≦Vdth, it outputs a low level (normal ejection state). The signal CMP is output to the outside from RSLT.

[0058] The nozzle status inspection is performed by sequentially selecting one heating element 103 and a corresponding pair of temperature detection elements 110 and 113. In other words, it is performed by sequentially selecting one of the control circuits 202a to 202d. For example, when the control circuit 202a is selected, the mask signal Seg_sel1 and the selection signal S1 are set to H level, and the heating element 103 and the temperature detection elements 110 and 113 of the control circuit 202a are selected. Then, the status of the nozzle corresponding to the heating element 103 is determined.

[0059] FIG. 7 is a diagram showing an example of time changes of the HE signal, the signals seg_sel1, the H1 signal, and the s1 signal, where the horizontal axis is time and the vertical axis is the logic level (H or L). The HE signal changes from L level to H level at time t1, changes from H level to L level at time t2, changes from L level to H level at time t4, and changes from H level to L level at time t5. The signal seg_sel1 changes from L level to H level at time t4. The H1 signal changes to H level only when both the HE signal and the signal seg_sel1 are at H level, so it is at H level from time t4 to time t5. The S1 signal is at H level from time t4 to time t5. During the H level, it is the status inspection time. The status inspection is performed from time t4 to time t6.

[0060] 7 shows the relationship between the HE signal, the signal seg_sel1, the H1 signal, and the s1 signal. However, the relationship between the HE signal, the signal seg_sel2, the H2 signal, and the s2 signal, the HE signal, the signal seg_sel3, the H3 signal, and the s3 signal, or the HE signal, the signal seg_sel4, the H4 signal, and the s4 signal is similar.

[0061] FIG. 6B is a simplified diagram of the heating element 103 and its drive circuit 214. FIG. 6C is a simplified diagram of the temperature detection elements 110 and 113 and their output circuit 213. One terminal of the temperature detection elements 110 and 113 is connected to a common potential of a contact PA. The other terminal of the temperature detection element 110 is connected to a connection wiring of the switch elements 209 and 210 connected in series at a contact PJ. The other terminal of the temperature detection element 110 is connected to a contact PB via the switch element 209, and is also connected to a contact PC via the switch element 210. The other terminal of the temperature detection element 113 is connected to a connection wiring of the switch elements 211 and 212 connected in series at a contact PK. The other terminal of the temperature detection element 113 is connected to a connection wiring of the switch elements 211 and 212 connected in series at a contact PD, and is also connected to a contact PE via the switch element 212.

[0062] The gate terminals of the switch elements 209 to 212 are connected to a contact PF, and a control signal (S1-S4) that connects or disconnects the drain terminals and source terminals of the switch elements 209 to 212 is input to the contact PF.

[0063] One terminal of the heating element 103 is connected to a contact PG, and the other terminal is connected to a contact PH via a switch element 216. A gate terminal of the switch element 216 is connected to a contact PI, and a control signal (Seg_sel1-Seg_sel4) that connects or disconnects the drain terminal and source terminal of the switch element 216 is input to the contact PI.

[0064] A current supply circuit 207 is connected to the contact PB, and a current supply circuit 208 is connected to the contact PD (FIG. 5). The switch element 210 is connected to one contact PC of the differential amplifier 220 via a buffer circuit 217, and the switch element 212 is connected to the other contact PE of the differential amplifier 220 via a buffer circuit 218.

[0065] In this embodiment, one terminal of each of the temperature detection elements 110 and 113 is connected to a common wiring 124 that is maintained at a predetermined potential. The potential of one terminal of each of the temperature detection elements 110 and 113 is stabilized, and it is possible to suppress individual fluctuations in potential due to external noise. Therefore, it is possible to reduce the influence of noise on the temperature detection elements 110 and 113. In addition, the voltage extraction wiring of each of the temperature detection elements 110 and 113 is reduced to only one current supply side terminal, and it is expected to reduce the circuit area. Furthermore, in this embodiment, the wiring 124 is connected to VSS, and VSS is the reference potential (ground) of the element substrate 1. It is possible to more reliably stabilize the potential of one terminal of each of the temperature detection elements 110 and 113.

[0066] In this embodiment, the determination circuit 219 is configured to be provided on the element substrate 1, but it may be provided outside the element substrate 1 in a control chip provided in the printhead 12. The determination circuit 219 may be provided outside the printhead 12 in a control chip (for example, the control circuit 17) provided in the printing device 10.

[0067] Second Embodiment Another example of the arrangement of the temperature detection elements 110 and 113 will be described with reference to FIGS. 8(A) and 8(B).

[0068] 8(A) is an example in which, in a plan view of the element substrate 1, a part of the temperature detection element 113 overlaps with the heating element 103. In this manner, at least a part of the temperature detection element 113 may overlap with the heating element 103. According to this configuration example, the space between the nozzles can be reduced, making it possible to arrange a higher density and larger number of nozzles in the element substrate 1.

[0069] The example of Fig. 8(B) shows an example in which the temperature detection element 113 is arranged on the short side of the heating element 103. This configuration example also makes it possible to reduce the space between the nozzles, and to arrange a higher density and a larger number of nozzles in the element substrate 1. Note that in the example of Fig. 8(B) as well, the temperature detection element 113 may be arranged so as to overlap the heating element 103, as in the example of Fig. 8(A). Furthermore, it becomes possible to arrange a higher density and a larger number of nozzles in the element substrate 1.

[0070] <Third embodiment> Two adjacent heat generating elements 103 may share one of a pair of temperature detecting elements 110 and 113. Fig. 9 is a plan view of the element substrate 1 showing one such example. In the example shown, each of the two adjacent heat generating elements 103 is provided with its own temperature detecting element 110. Meanwhile, a single temperature detecting element 113 is disposed between the two adjacent heat generating elements 103 to be shared by these elements. The temperature detecting element 113 is formed so as to have equal thermal sensitivity to the two heat generating elements 103, and in this embodiment, the temperature detecting element 113 is disposed at a position equidistant from the central portion CT of each heat generating element 103.

[0071] Fig. 10 is a circuit diagram of the element substrate 1 in this embodiment. As an example, a configuration in which the nozzle array circuit 201 includes four heat elements 103 (an example in which there are four nozzles) similar to the example in Fig. 5 will be illustrated, and a configuration different from the example in Fig. 5 will be described.

[0072] The output circuits 213b and 213d of this embodiment do not have switch elements 211 and 212 corresponding to the temperature detection element 113. That is, the temperature detection element 113 of the output circuit 213a is shared between the heat elements 103 of the drive circuits 214a and 214b. Also, the temperature detection element 113 of the output circuit 213c is shared between the heat elements 103 of the drive circuits 214c and 214d.

[0073] For this purpose, an OR gate 601A to which the selection signals S1 and S2 are inputted is provided, and an OR gate 601B to which the selection signals S3 and S4 are inputted is also provided. The output of the OR gate 601A is inputted to each gate terminal of the switch elements 211 and 212. When the selection signal S1 becomes H level, the temperature detection elements 110 and 113 of the output circuit 213a are energized, and each piece of temperature information is outputted from the switch elements 210 and 212. When the selection signal S2 becomes H level, the temperature detection elements 110 of the output circuit 213b and the temperature detection elements 113 of the output circuit 213a are energized, and temperature information is outputted from the switch element 210 of the output circuit 213b and the switch element 212 of the output circuit 213a, respectively.

[0074] Similarly, when the selection signal S3 goes to H level, the temperature detection elements 110 and 113 of the output circuit 213c are energized, and each piece of temperature information is output from the switch elements 210 and 212. When the selection signal S4 goes to H level, the temperature detection elements 110 and 113 of the output circuit 213d and the output circuit 213c are energized, and temperature information is output from the switch element 210 of the output circuit 213d and the switch element 212 of the output circuit 213c, respectively.

[0075] In this way, by sharing the temperature detection element 113 between two adjacent heat generating elements 103, the number of temperature detection elements can be reduced. Also, the distance between the nozzles can be reduced, making it possible to arrange a higher density and a larger number of nozzles within the element substrate 1. Furthermore, the number of circuit elements related to the temperature detection element 113 can also be reduced, resulting in a reduced circuit area.

[0076] <Other embodiments> The present invention is not limited to the above embodiment. For example, in the examples of Fig. 5 and Fig. 10, the number of nozzles in the element substrate 1 is 4 for convenience, but the number of nozzles may be, for example, 512. The nozzle array circuit 201 may have multiple rows instead of one row. The shape of the temperature detection element 110 is exemplified as a Z-shape, but is not limited to this. The temperature detection element 110 may have any shape that straddles the heating element 103 in the width direction near the center of the heating element 103.

[0077] <Summary of the embodiment> The above embodiment discloses at least the following element substrate and recording apparatus.

[0078] Item 1. a first heating element that generates thermal energy for discharging liquid when power is supplied thereto; a first temperature detection element for detecting a temperature of the first heating element; a second temperature detection element for detecting a temperature of the first heating element; a first output circuit that energizes the first temperature detection element to output a voltage at one terminal of the first temperature detection element as temperature information; and a second output circuit that energizes the second temperature detection element to output a voltage at one terminal of the second temperature detection element as temperature information, the other terminal of the first temperature detection element and the other terminal of the second temperature detection element are connected to a common wiring that is maintained at a predetermined potential. 1. An element substrate comprising:

[0079] Item 2. Item 1. An element substrate according to item 1, The predetermined potential is a reference potential of the element substrate. 1. An element substrate comprising:

[0080] Item 3. The element substrate according to item 1 or 2, a first current supply circuit that supplies a current to the first temperature detection element via the first output circuit; a second current supply circuit that supplies a current to the second temperature detection element via the second output circuit; a current source that supplies current to the first current supply circuit and the second current supply circuit; the first current supply circuit and the second current supply circuit form a current mirror circuit; 1. An element substrate comprising:

[0081] Item 4. The element substrate according to any one of items 1 to 3, the first temperature detection element and the second temperature detection element have different shortest distances to a central portion of the first heat generating element; 1. An element substrate comprising:

[0082] Item 5. The element substrate according to any one of items 1 to 4, The first heating element is formed in a strip shape, one of the first temperature detection element and the second temperature detection element crosses the first heating element in a width direction, and the other does not cross the first heating element in a width direction; 1. An element substrate comprising:

[0083] Item 6. Item 5. The element substrate according to any one of items 1 to 5, a first buffer circuit to which the temperature information output from the first output circuit is input; a second buffer circuit to which the temperature information output from the second output circuit is input; a differential amplifier that amplifies and outputs a difference between the temperature information output from the first buffer circuit and the second buffer circuit, 1. An element substrate comprising:

[0084] Item 7. Item 6. An element substrate according to any one of items 1 to 6, a second heating element that generates thermal energy for discharging liquid when power is supplied to the second heating element; a third temperature detection element for detecting a temperature of the second heating element; a third output circuit that energizes the third temperature detection element to output a voltage at one terminal of the third temperature detection element as temperature information, The second temperature detection element also detects the temperature of the second heating element; The other terminal of the third temperature detection element is connected to the common wiring. 1. An element substrate comprising:

[0085] Item 8. Item 7: The element substrate according to any one of items 1 to 7, the first heating element is a film-like resistor, the first temperature detection element and the second temperature detection element are each a film-like resistor, an insulating material is interposed between the first heating element and the first temperature detection element and between the first heating element and the second temperature detection element; The element substrate is characterized by the above.

[0086] Item 9. Item 10. The element substrate according to any one of items 1 to 8, The first output circuit includes: a first switch element that energizes the first temperature detection element in response to an input of a selection signal; a second switch element connected in series with the first switch element and configured to output the temperature information in response to an input of the selection signal; the one terminal of the first temperature detection element is connected to a connection wiring between the first switch element and the second switch element; 1. An element substrate comprising:

[0087] Item 10. A recording device having a recording head that ejects liquid onto a recording medium, The recording head includes an element substrate according to any one of items 1 to 9. A recording device comprising:

[0088] The invention is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0089] 1 element substrate, 103 heat generating element, 110 temperature detecting element, 113 temperature detecting element, 124 wiring

Claims

1. a first heating element that generates thermal energy for discharging liquid when power is supplied thereto; a first temperature detection element for detecting a temperature of the first heating element; a second temperature detection element for detecting a temperature of the first heating element; a first output circuit that energizes the first temperature detection element to output a voltage at one terminal of the first temperature detection element as temperature information; and a second output circuit that energizes the second temperature detection element to output a voltage at one terminal of the second temperature detection element as temperature information, the other terminal of the first temperature detection element and the other terminal of the second temperature detection element are connected to a common wiring that is maintained at a predetermined potential.

1. An element substrate comprising:

2. 2. The element substrate according to claim 1, The predetermined potential is a reference potential of the element substrate.

1. An element substrate comprising:

3. 2. The element substrate according to claim 1, a first current supply circuit that supplies a current to the first temperature detection element via the first output circuit; a second current supply circuit that supplies a current to the second temperature detection element via the second output circuit; a current source that supplies current to the first current supply circuit and the second current supply circuit; the first current supply circuit and the second current supply circuit form a current mirror circuit; 1. An element substrate comprising:

4. 2. The element substrate according to claim 1, the first temperature detection element and the second temperature detection element have different shortest distances to a central portion of the first heat generating element; 1. An element substrate comprising:

5. 2. The element substrate according to claim 1, The first heating element is formed in a strip shape, one of the first temperature detection element and the second temperature detection element crosses the first heating element in a width direction, and the other does not cross the first heating element in a width direction; 1. An element substrate comprising:

6. 2. The element substrate according to claim 1, a first buffer circuit to which the temperature information output from the first output circuit is input; a second buffer circuit to which the temperature information output from the second output circuit is input; a differential amplifier that amplifies and outputs a difference between the temperature information output from the first buffer circuit and the second buffer circuit, 1. An element substrate comprising:

7. 2. The element substrate according to claim 1, a second heating element that generates thermal energy for discharging liquid when power is supplied thereto; a third temperature detection element for detecting a temperature of the second heating element; a third output circuit that energizes the third temperature detection element to output a voltage at one terminal of the third temperature detection element as temperature information; The second temperature detection element also detects the temperature of the second heating element; The other terminal of the third temperature detection element is connected to the common wiring.

1. An element substrate comprising:

8. 2. The element substrate according to claim 1, the first heating element is a film-like resistor, the first temperature detection element and the second temperature detection element are each a film-like resistor, an insulating material is interposed between the first heating element and the first temperature detection element and between the first heating element and the second temperature detection element; The element substrate is characterized by the above.

9. 2. The element substrate according to claim 1, The first output circuit includes: a first switch element that energizes the first temperature detection element in response to an input of a selection signal; a second switch element connected in series with the first switch element and configured to output the temperature information in response to an input of the selection signal; the one terminal of the first temperature detection element is connected to a connection wiring between the first switch element and the second switch element; 1. An element substrate comprising:

10. A recording device having a recording head that ejects liquid onto a recording medium, The recording head comprises the element substrate according to claim 1. A recording apparatus comprising:

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