Method for detecting the temperature of a head chip and liquid dispensing apparatus

Abstract

This technology provides accurate temperature detection by compensating for the deterioration of detection accuracy due to changes over time in the resistance thermometer, without requiring the use of special equipment for temperature calibration. [Solution] This disclosure provides a method for detecting the temperature of a head tip in a liquid dispensing device having a head tip including a plurality of nozzles for dispensing liquid, using a resistance thermometer provided on the head tip. This method comprises: (a) determining a first detection temperature of the head tip using a resistance thermometer under a plurality of ambient temperatures, and determining a second detection temperature using a temperature detection element provided on the liquid dispensing device; (b) obtaining calibration information for calibrating the temperature detected by the resistance thermometer using the difference between the first detection temperature and the second detection temperature under a plurality of ambient temperatures; and (c) determining the temperature detected by the head tip using a resistance thermometer, and correcting the temperature detected by the head tip using the calibration information.

Description

Technical Field

[0001] The present disclosure relates to a method for detecting the temperature of a head chip and a liquid ejection device.

Background Art

[0002] Patent Document 1 discloses an inkjet recording apparatus. In this prior art, a recording head is detected using a diode sensor, and the detected temperature of the recording head is corrected by correcting its offset.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when a resistance temperature detector is used as a temperature sensor, both the offset and the slope may change over time. Therefore, the above prior art cannot be applied to the resistance temperature detector, and a special device for temperature calibration is required. Thus, a technique that can compensate for the deterioration of detection accuracy due to the change over time of the resistance temperature detector and perform temperature detection with high accuracy without using a special device for temperature calibration other than the liquid ejection device is desired.

Means for Solving the Problems

[0005] According to a first embodiment of the present disclosure, a method is provided for detecting the temperature of a head tip in a liquid dispensing device having a head tip including a plurality of nozzles for dispensing liquid, using a resistance thermometer provided on the head tip. This method comprises: (a) determining a first detection temperature of the head tip using the resistance thermometer under a plurality of ambient temperatures, and determining a second detection temperature using a temperature detection element provided on the liquid dispensing device; (b) obtaining calibration information for calibrating the temperature detected by the resistance thermometer using the difference between the first detection temperature and the second detection temperature under the plurality of ambient temperatures; and (c) determining the detection temperature of the head tip using the resistance thermometer, and correcting the detection temperature of the head tip using the calibration information.

[0006] A second embodiment of the present disclosure provides a liquid dispensing device for dispensing liquid. The liquid dispensing device includes a head tip including a plurality of nozzles for dispensing the liquid, a resistance thermometer provided on the head tip, a temperature detection element provided separately from the resistance thermometer, and a temperature detection correction unit for correcting the detected temperature of the head tip detected using the resistance thermometer. The temperature detection correction unit is configured to perform the following: (a) a process of determining a first detected temperature of the head tip using the resistance thermometer and determining a second detected temperature using the temperature detection element under a plurality of ambient temperatures; (b) a process of determining calibration information for calibrating the temperature detected by the resistance thermometer using the difference between the first detected temperature and the second detected temperature under the plurality of ambient temperatures; and (c) a process of determining the detected temperature of the head tip using the resistance thermometer and correcting the detected temperature of the head tip using the calibration information. [Brief explanation of the drawing]

[0007] [Figure 1] An explanatory diagram showing the configuration of the liquid dispensing device in the embodiment. [Figure 2] Functional block diagram of the control unit and liquid dispensing head. [Figure 3] An explanatory diagram showing the arrangement of nozzle rows and resistance thermometers. [Figure 4] Cross-sectional view of the head tip. [Figure 5] Conceptual diagram of a liquid dispensing head. [Figure 6] A graph comparing the changes over time between a resistance thermometer and a temperature sensing element. [Figure 7] An explanatory diagram showing the method for determining the calibration curve of a resistance thermometer. [Figure 8] A graph comparing the time-dependent changes in a resistance thermometer and a temperature sensing element when there is an initial difference. [Figure 9] An explanatory diagram showing how to determine the calibration curve of a resistance thermometer when there is an initial difference. [Figure 10] A flowchart illustrating the processing procedure for detecting the temperature of the head chip and correcting the drive waveform. [Modes for carrying out the invention]

[0008] Figure 1 is an explanatory diagram showing the configuration of a liquid ejection device 400 in an embodiment. The liquid ejection device 400 is an inkjet printing device that ejects ink, which is an example of a liquid, onto a medium PM. A liquid storage unit 410 for storing ink can be attached to the liquid ejection device 400. The liquid ejection device 400 performs printing by ejecting the ink in the liquid storage unit 410 toward the medium PM. The liquid ejection device 400 comprises a liquid ejection head 100, a control unit 420, a moving mechanism 430, a transport mechanism 440, and a platen 450.

[0009] The liquid ejection head 100 has two head tips 101 and 102. However, the liquid ejection head 100 can be configured to have any number of head tips. Each of the head tips 101 and 102 is equipped with multiple nozzles 200, which eject liquid ink supplied from the liquid reservoir 410. Specific embodiments of the liquid reservoir 410 include, for example, a cartridge detachable from the liquid ejection device 400, a bag-shaped ink pack made of a flexible film, and a container such as an ink tank to which ink can be refilled. The ink ejected from the nozzles 200 lands on the medium PM. The medium PM is typically printing paper. However, the medium PM is not limited to printing paper and may be any material such as resin film or fabric.

[0010] The composition of the ink is not particularly limited. For example, it may be a water-based ink in which a colorant such as a dye or pigment is dissolved in an aqueous solvent, a solvent-based ink in which a colorant is dissolved in an organic solvent, or an ultraviolet-curing ink. The liquid dispensing device 400 may also dispens other types of liquids, such as paint, instead of ink.

[0011] The moving mechanism 430 comprises a ring-shaped belt 432 and a carriage 434 fixed to the belt 432. The carriage 434 holds the liquid discharge head 100. The moving mechanism 430 can move the liquid discharge head 100 back and forth along the X direction by rotating the ring-shaped belt 432 in both directions.

[0012] The transport mechanism 440 transports the medium PM along the Y direction in between movements of the liquid discharge head 100 by the moving mechanism 430. The Y direction is perpendicular to the X direction. In this embodiment, the X and Y directions are horizontal. The Z direction intersects the X and Y directions. In this embodiment, the Z direction is vertically downward. The liquid discharge head 100 discharges liquid along the Z direction while being transported along the X direction. The Z direction is also called the "discharge direction".

[0013] The platen 450 is a support portion that supports the medium PM that receives the landing of the liquid discharged from the liquid discharge head 100. A platen heater 452 is provided on the platen 450. The platen heater 452 can heat the platen 450 to promote the drying of the liquid on the medium PM. As will be described later, the platen heater 452 can be used for the purpose of raising the ambient temperature of the head chips 101 and 102. However, other devices other than the platen heater 452 may be used to change the ambient temperature of the head chips 101 and 102. For example, the ambient temperature may be changed using a heater or an air conditioner installed in the room that houses the liquid discharge device 400.

[0014] As shown enlarged in the lower part of FIG. 1, a temperature detection element 106 is installed in the main body of the liquid discharge head 100, and a temperature detection element 436 is also installed on the carriage 434. As the temperature detection elements 106 and 436, a thermistor, a thermocouple, an IC temperature sensor, or the like can be used. As will be described later, the temperature detection elements 106 and 436 can be used to detect the ambient temperature of the head chips 101 and 102 when obtaining calibration information regarding the resistance temperature detectors for detecting the temperatures of the head chips 101 and 102. In the present embodiment, the ambient temperature of the head chips 101 and 102 is detected using the temperature detection element 436 installed on the carriage 434.

[0015] The temperature detection elements 106 and 436 are preferably composed of elements different from the resistance temperature detectors for detecting the temperatures of the head chips 101 and 102. Further, the temperature detection elements 106 and 436 are preferably provided in the liquid discharge device 400 for other purposes than detecting the ambient temperature of the head chips 101 and 102.

[0016] The control unit 420 controls the liquid discharge operation from the liquid discharge head 100. The control unit 420 controls the movement mechanism 430, the conveyance mechanism 440, and the liquid discharge head 100 to form an image on the medium PM.

[0017] FIG. 2 is a functional block diagram of the control unit 420 and the liquid ejection head 100. In FIG. 2, the parts related to the temperature detection of the head chips 101 and 102 and the temperature correction of the drive signal are depicted.

[0018] The control unit 420 includes a control signal supply unit 421, a drive waveform correction unit 422, a drive waveform storage unit 423, drive signal generation units 424 and 425, and a detected temperature correction unit 426.

[0019] The control unit 420 can be realized by a computer having a processor and a memory. The functions of the control signal supply unit 421, the drive waveform correction unit 422, and the detected temperature correction unit 426 can be realized by the processor executing a computer program stored in the memory. However, part or all of these functions may be realized by a hardware circuit.

[0020] The control signal supply unit 421 supplies various control signals including a dot control signal SI and a dot clock signal CL to the drive circuits 71 and 72 of the liquid ejection head 100. The dot control signal SI is a signal indicating the presence or absence of dots and the dot size formed on the medium PM, and is also called a print signal. The waveform of the drive signal Vin for driving the piezoelectric element 80 to eject liquid from each nozzle 200 is determined according to the dot control signal SI. The dot clock signal CL is a signal defining the dot period.

[0021] The drive waveform correction unit 422 corrects the drive waveform data DC1 and DC2, which represent the waveforms of the common drive signals COM1 and COM2, according to the detected temperature of the head chips 101 and 102. The drive waveform storage unit 423 has correction data stored in advance according to the detected temperature of the head chips 101 and 102. The drive waveform correction unit 422 reads first correction data from the drive waveform storage unit 423 according to the detected temperature of the first head chip 101 and corrects the drive waveform data DC1 for the first common drive signal COM1 according to this first correction data. Furthermore, the drive waveform correction unit 422 reads second correction data from the drive waveform storage unit 423 according to the detected temperature of the second head chip 102 and corrects the drive waveform data DC2 for the second common drive signal COM2 according to this second correction data.

[0022] The drive signal generation units 424 and 425 generate common drive signals COM1 and COM2, respectively, using temperature-corrected drive waveform data DC1 and DC2. The common drive signals COM1 and COM2 are drive signals that are applied in common to multiple piezoelectric elements 80. In the first embodiment, the first common drive signal COM1 is applied in common to multiple piezoelectric elements 80 of the first head chip 101, and the second common drive signal COM2 is applied in common to multiple piezoelectric elements 80 of the second head chip 102.

[0023] The temperature detection correction unit 426 corrects the detected temperature signals Dt1 and Dt2 output from the temperature detection circuit 310 of the liquid discharge head 100 to generate corrected detected temperature signals Dct1 and Dct2. The temperatures of the head tips 101 and 102 are detected using resistance thermometers 301 and 302, respectively. However, the characteristics of the resistance thermometers 301 and 302 change over time. Therefore, the temperature detection correction unit 426 obtains calibration information CI to compensate for the changes in resistance thermometers 301 and 302 over time, and corrects the detected temperatures of the head tips 101 and 102 by applying the calibration information CI to the detected temperature signals Dt1 and Dt2 output from the temperature detection circuit 310. When obtaining the calibration information CI, a temperature detection element 436 that detects the ambient temperature of the head tips 101 and 102 and a platen heater 452 are used. The method for obtaining the calibration information CI will be described later.

[0024] The liquid discharge head 100 includes a drive circuit 71 for the first head chip 101, a drive circuit 72 for the second head chip 102, and a temperature detection circuit 310.

[0025] The first head chip 101 includes a plurality of piezoelectric elements 80 that apply pressure to the liquid in order to discharge the liquid from each of the plurality of nozzles 200, and a resistance thermometer 301 for detecting the temperature of the first head chip 101. The second head chip 102 similarly includes a plurality of piezoelectric elements 80 and a resistance thermometer 302.

[0026] The drive circuit 71 for the first head chip 101 generates a drive signal Vin for driving each piezoelectric element 80 within the first head chip 101 in accordance with the first common drive signal COM1 and the dot control signal SI. Specifically, the drive circuit 71 generates a drive signal Vin that includes part or all of the waveform of the first common drive signal COM1 in accordance with the dot control signal SI for each dot period defined by the dot clock signal CL. For example, if the first head chip 101 contains 100 piezoelectric elements 80, 100 drive signals Vin are generated individually. The drive circuit 72 for the second head chip 102 operates similarly.

[0027] The temperature detection circuit 310 generates a detected temperature signal Dt1 indicating the temperature of the first head chip 101 using a resistance thermometer 301. The temperature detection circuit 310 further generates a detected temperature signal Dt2 indicating the temperature of the second head chip 102 using a resistance thermometer 302. The detected temperature signals Dt1 and Dt2 are supplied to the detected temperature correction unit 426 of the control unit 420.

[0028] Figure 3 is an explanatory diagram showing the arrangement of nozzle rows and resistance thermometers. The first head tip 101 has two nozzle rows NL1 and NL2, and the second head tip 102 has two nozzle rows NL3 and NL4. Each of the nozzle rows NL1 to NL4 has nozzles 200 arranged along the Y direction. The resistance thermometer 301 of the first head tip 101 is arranged to surround the outer circumference of the two nozzle rows NL1 and NL2 of the first head tip 101. The resistance thermometer 302 of the second head tip 102 is arranged to surround the outer circumference of the two nozzle rows NL3 and NL4 of the second head tip 102. However, various other arrangements of resistance thermometers 301 and 302 are possible. For example, platinum resistance thermometers can be used as resistance thermometers 301 and 302.

[0029] Figure 4 is a cross-sectional view of the head tip 101. The head tip 101 has a common liquid chamber 210 into which liquid is supplied from the outside, and nozzle-specific flow channels 220 connecting the common liquid chamber 210 to individual nozzles 200. The common liquid chamber 210 is provided in common to multiple nozzles 200 that constitute one nozzle row. That is, the common liquid chamber 210 temporarily stores the liquid supplied from the liquid storage unit 410 and supplies the liquid to multiple nozzle-specific flow channels 220 for multiple nozzles 200. In Figure 4, the nozzle-specific flow channels 220 for the nozzles 200 of the first nozzle row NL1 and the nozzle-specific flow channels 220 for the nozzles 200 of the second nozzle row NL2 have the same structure.

[0030] Each nozzle channel 220 has a pressure chamber 230 that applies pressure to the liquid. A piezoelectric element 80 is installed in the pressure chamber 230 to change the volume of the pressure chamber 230.

[0031] The common liquid chamber 210 and the multiple nozzle-specific flow paths 220 are mainly formed by a connecting plate 140 and a pressure chamber substrate 150. The connecting plate 140 is a laminate formed by stacking multiple plate-shaped members. The housing portion 160 and the pressure chamber substrate 150 are installed on the upper surface of the connecting plate 140. In a plan view in the Z direction, the pressure chamber substrate 150 is located inside the housing portion 160. A diaphragm 170 is installed on the upper surface of the pressure chamber substrate 150. The pressure chamber 230 is a space defined by the connecting plate 140, the diaphragm 170, and the pressure chamber substrate 150. The pressure chamber substrate 150 is formed, for example, by processing a silicon single crystal substrate using semiconductor processing technology. The connecting plate 140 can also be formed by stacking multiple silicon single crystal substrates.

[0032] A nozzle plate 120 is installed on the lower surface of the communication plate 140. The lower end of the common liquid chamber 210 is sealed with a flexible sealing film 130 made of a resin film or a thin film of metal.

[0033] A wiring board 50 is bonded to the upper surface of the diaphragm 170. The wiring board 50 is a mounting component on which multiple wirings are formed for electrically connecting the control unit 420 and the head chip 101. A drive circuit 71 for driving the piezoelectric element 80 is mounted on the wiring board 50. When the piezoelectric element 80 vibrates, the vibration is transmitted to the pressure chamber 230, causing pressure fluctuations in the pressure chamber 230. The liquid is discharged from the nozzle 200 by the pressure generated by the piezoelectric element 80. The piezoelectric element 80 has a first electrode 81, a second electrode 82, and a piezoelectric body 83 positioned between the first electrode 81 and the second electrode 82. The first electrode 81 is connected to a drive wiring 84. The wiring between the drive wiring 84 and the drive circuit 71 is not shown in the figure. The first electrode 81 is provided individually for each piezoelectric element 80. Regarding the second electrode 82 and piezoelectric element 83, one second electrode 82 and one piezoelectric element 83 are provided that are common to multiple piezoelectric elements 80 that drive one row of nozzles 200.

[0034] A resistance thermometer 301 is positioned near the piezoelectric element 80. The resistance thermometer 301 is positioned between the piezoelectric element 83 and the diaphragm 170. As shown in Figure 3, the resistance thermometer 301 is positioned to surround the multiple nozzles 200 in a plan view. It is preferable that the resistance thermometer 301 has a portion that contacts the piezoelectric element 83 of the piezoelectric element 80.

[0035] Figure 5 is a conceptual diagram of the liquid discharge head 100 of the first embodiment, which is a simplified version of the configuration described in Figures 1 to 4. The first drive circuit 71 generates a drive signal Vin1 to supply to each piezoelectric element 80 of the first nozzle row NL1 and a drive signal Vin2 to supply to each piezoelectric element 80 of the second nozzle row NL2, according to the first common drive signal COM1 and the dot control signal SI, at each dot period defined by the dot clock signal CL. The second drive circuit 72 generates a drive signal Vin3 to supply to each piezoelectric element 80 of the third nozzle row NL3 and a drive signal Vin4 to supply to each piezoelectric element 80 of the fourth nozzle row NL4, according to the second common drive signal COM2 and the dot control signal SI, at each dot period defined by the dot clock signal CL. The temperature detection circuit 310 generates a detected temperature signal Dt1 indicating the detected temperature of the first head chip 101 using a resistance thermometer 301. The temperature detection circuit 310 further generates a detected temperature signal Dt2 indicating the temperature detected by the second head chip 102 using the resistance thermometer 302.

[0036] A temperature detection element 106 is installed on the body of the liquid discharge head 100, and another temperature detection element 436 is installed on the carriage 434. As described above, in this embodiment, the ambient temperature of the head tips 101 and 102 is detected using the temperature detection element 436 installed on the carriage 434. It is preferable that the temperature detection element 436 is provided on the surface facing the platen 450. It is also preferable that the temperature detection element 436 is provided on the same plane as the nozzle surface of the head tips 101 and 102. By heating the environment of the head tips 101 and 102 using the platen heater 452, it is easy to achieve a state in which the temperature detection element 436 and the resistance thermometers 301 and 302 detect the same ambient temperature.

[0037] Figure 6 is a graph comparing the changes over time between the resistance thermometer 301 and the temperature sensing element 436. In Figure 6, the horizontal axis represents the true temperature (True), and the vertical axis represents the detected temperature (Tats) of the resistance thermometer 301 and the detected temperature (Tref) of the temperature sensing element 436. The following description will focus on the resistance thermometer 301 for head chip 101, but the same applies to the resistance thermometer 302 for head chip 102.

[0038] The resistance thermometer 301 on the head chip 101 undergoes relatively large changes over time, while the temperature sensing element 436 on the platen 450 undergoes negligible changes over time. The reason for the changes in the resistance thermometer 301 over time is presumed to be primarily due to plastic deformation of the resistance thermometer 301 caused by the deformation of the head chip 101. For example, when the head chip 101 deforms due to the effects of heat and humidity, the wiring pattern of the resistance thermometer 301 undergoes plastic deformation, causing a change in resistance. Also, when external forces such as paper jams are applied to the head chip 101, the wiring pattern of the resistance thermometer 301 undergoes plastic deformation, causing a change in resistance. Furthermore, it is also possible that the platinum wiring of the resistance thermometer 301 oxidizes due to heat generated by the current, causing the wiring to thin and thus increasing the resistance.

[0039] In the initial stages of use of the liquid dispensing device 400, the detected temperature Tats_0 of the resistance thermometer 301 and the detected temperature Tref_0 of the temperature sensing element 436 are almost identical. Over time, the detected temperature Tats_1 of the resistance thermometer 301 decreases overall. On the other hand, the detected temperature Tref_1 of the temperature sensing element 436 obtained at the same time is almost the same as the initial detected temperature Tref_0. Therefore, by utilizing these characteristics, it is possible to obtain calibration information CI that shows the calibration curve of the resistance thermometer 301.

[0040] Figure 7 is an explanatory diagram showing a method for determining the calibration curve CC of the resistance thermometer 301. In the left-hand diagram of Figure 7, the horizontal axis is the ambient temperature Tamb, and the vertical axis is the detection temperature Tats_1 of the resistance thermometer 301 and the detection temperature Tref_1 of the temperature detection element 436. First, temperature detection is performed using the resistance thermometer 301 and the temperature detection element 436 under a constant ambient temperature where the actual temperatures of the resistance thermometer 301 and the temperature detection element 436 are approximately equal. It is preferable to use multiple ambient temperatures as the "constant ambient temperature," including a first ambient temperature Tamb1 which is room temperature and a second ambient temperature Tamb2 which is raised using the platen heater 452. Alternatively, the first ambient temperature Tamb1 may be a temperature higher than room temperature, and the second ambient temperature Tamb2 may be a temperature further raised than the first ambient temperature Tamb1. For each ambient temperature Tamb1 and Tamb2, the difference ΔT1 and ΔT2 between the temperature detected by the resistance thermometer 301 (Tats_1) and the temperature detected by the temperature sensing element 436 (Tref_1) is obtained.

[0041] The right side of Figure 7 shows the calibration curve CC of the resistance thermometer 301. The horizontal axis represents the detected temperature Tat of the resistance thermometer 301, and the vertical axis represents the temperature correction value ΔT. This calibration curve CC is a curve that shows the relationship in which the difference ΔT between the detected temperature ΔT of the resistance thermometer 301 and the temperature detection element 436 at multiple ambient temperatures Tamb1 and Tamb2 changes according to the detected temperature Tat of the resistance thermometer 301. In the example in Figure 7, the calibration curve CC is a straight line. Thus, in this embodiment, even if the temperature detection characteristics of the resistance thermometer 301 change in both slope and offset over time, the detected temperature can be compensated to compensate for that change over time.

[0042] Calibration information CI can include various types of information, such as a function that shows the shape of the calibration curve CC, or coordinate values ​​that represent multiple points on the calibration curve CC.

[0043] Furthermore, the difference ΔT between the temperature detected by the resistance thermometer 301 and the temperature detection element 436 may be calculated for three or more ambient temperature Tambs. In this way, it is possible to obtain calibration information CI that shows the calibration curve CC, which is a curve in the narrow sense rather than a straight line.

[0044] Figure 8 is a graph comparing the time-dependent changes of the resistance thermometer 301 and the temperature detection element 436 when there is an initial difference Δini, and Figure 9 is an explanatory diagram showing how to determine the calibration curve CC when there is an initial difference Δini. The initial difference Δini is the difference that exists between the detected temperature Tats_0 of the resistance thermometer 301 and the detected temperature Tref_0 of the temperature detection element 436 in a specific initial state, such as the initial use of the liquid dispensing device 400.

[0045] If a non-zero initial difference Δini exists, it is possible to calibrate the temperature detection state of the resistance thermometer 301 to match the initial state. Specifically, as shown in Figure 9, the time-dependent changes in the difference δT1 and δT2 are obtained by subtracting the initial difference Δini from the differences ΔT1a and ΔT2a between the detected temperature Tats_1 of the resistance thermometer 301 and the detected temperature Tref_1 of the temperature detection element 436, and calibration information CI representing the calibration curve CC that compensates for these time-dependent changes δT1 and δT2 is obtained. In this way, only the time-dependent changes δT1 and δT2 are compensated by the calibration information CI, so the temperature detection state of the resistance thermometer 301 can be matched to the initial state. The initial difference Δini can be pre-registered in the detected temperature correction unit 426.

[0046] In the examples in Figures 8 and 9, the initial difference Δini is assumed to be constant regardless of temperature, but the initial difference Δini may be assumed to change depending on the temperature. If the initial difference Δini is temperature-dependent, it can be registered as a value that depends, for example, on the temperature detected by the temperature sensing element 436.

[0047] Furthermore, if a non-zero initial difference Δini exists, it is also possible to calibrate the resistance thermometer 301 to match the temperature detected by the temperature detection element 436. Specifically, even when a non-zero initial difference Δini exists, as shown in Figures 8 and 9, calibration information CI representing a calibration curve CC that compensates for the difference ΔT1a and ΔT2a between the detection temperatures of the resistance thermometer 301 and the temperature detection element 436 can be obtained, similar to the cases in Figures 6 and 7. In this way, the difference ΔT1a and ΔT2a in the detection temperatures is compensated by the calibration information CI, so the detection temperature of the resistance thermometer 301 can be matched to the detection temperature of the temperature detection element 436.

[0048] As can be seen from the examples in Figures 6 to 9, regardless of the presence or absence of the initial difference Δini, it is possible to obtain calibration information CI for calibrating the temperature detected by the resistance thermometer 301 using the differences ΔT1 and ΔT2 between the detected temperature Tats_1 and the detected temperature Tref_1.

[0049] The temperature detection correction unit 426 can determine the corrected temperature by adding the temperature correction value shown by the calibration curve CC to the detected temperature Tat obtained using the resistance thermometer 301. As a result, it is possible to improve the accuracy of temperature detection.

[0050] Furthermore, during the period in which the detection temperature of the head chip 101 is determined using the resistance thermometer 301, it is preferable to maintain the first electrode 81 and the second electrode 82 of the piezoelectric element 80 at a constant potential. That is, it is preferable to maintain the first electrode 81 at a first potential and the second electrode 82 at a second potential. For example, the first potential is a reference potential higher than the ground potential, and the second potential is the ground potential. This prevents noise in the detection temperature that occurs when a drive signal with voltage changes is applied to the piezoelectric element 80, and allows for more accurate calibration of the resistance thermometer 301.

[0051] Figure 10 is a flowchart showing the processing procedure for head chip temperature detection and drive waveform correction. In step S10, the liquid dispensing device 400 is started by the user. In step S20, as described in Figure 7, the detection temperature correction unit 426 determines the first detection temperature Tats using the resistance thermometer 301 and the second detection temperature Tref using the temperature detection element 436 under multiple ambient temperature Tambs. Specifically, in each ambient temperature Tamb, the unit maintains the ambient temperature Tamb until the temperature changes of the resistance thermometer 301 and the temperature detection element 436 stabilize, and then determines the temperatures of the first detection temperature Tats and the second detection temperature Tref. At least one of the multiple ambient temperature Tambs may be the room temperature of the room in which the liquid dispensing device 400 is housed. At least one of the multiple ambient temperature Tambs may also be set by heating with the platen heater 452. In step S30, the detection temperature correction unit 426 uses the difference ΔT between the first detection temperature Tats and the second detection temperature Tref to determine the calibration information CI for the resistance thermometer 301. The detection temperature correction unit 426 can also determine the calibration information CI for the resistance thermometer 302 separately from the calibration information CI for the resistance thermometer 301.

[0052] In step S40, the liquid discharge process by the liquid discharge device 400 is started. In step S50, the temperature detection circuit 310 determines the detected temperatures of the head chips 101 and 102 using the resistance thermometers 301 and 302, respectively. In step S60, the detected temperature correction unit 426 corrects the detected temperatures of the head chips 101 and 102, respectively, using the calibration information CI. In step S70, the drive waveform correction unit 422 corrects the common drive signals COM1 and COM2 according to the corrected detected temperatures.

[0053] In step S80, it is determined whether to terminate or continue the processes in steps S50 to S70. If the processes in steps S50 to S70 are to be continued, the process returns to step S50 and the processes in steps S50 to S70 are executed again. On the other hand, if the processes in steps S50 to S70 are to be terminated, the process in Figure 10 is also terminated. For example, when the power to the liquid dispensing device 400 is turned off, the process in Figure 10 is terminated. The processes in steps S50 to S70 may be executed periodically, or they may be executed when specific processing start conditions are met.

[0054] It is preferable that the processes in steps S20 and S30 are performed after the liquid dispensing device 400 is started and before the liquid dispensing process in which the liquid is dispensed. Furthermore, it is preferable that the processes in steps S50 to S70 are performed during or after the liquid dispensing process. In this way, calibration information CI can be obtained before the liquid dispensing process, and the detection temperature of the head tip can be accurately determined during or after the liquid dispensing process using this calibration information CI.

[0055] In the above explanation, the waveforms of the common drive signals COM1 and COM2 are corrected according to the detected temperature of the head chips 101 and 102. However, the detected temperature of the head chips 101 and 102 may be used for other purposes. For example, temperature adjustment using the platen heater 452 may be performed according to the detected temperature of the head chips 101 and 102. In this case, temperature adjustment may be performed according to the average value of the detected temperatures of the head chips 101 and 102, or according to the maximum or minimum value of the detected temperature over a certain period.

[0056] In the embodiment described above, the ambient temperature of the head tips 101 and 102 was detected using a temperature detection element 436 installed on the carriage 434. However, a temperature detection element 106 installed on the body of the liquid discharge head 100 may be used instead. The time required for the temperature change of the temperature detection element 106 to stabilize tends to be longer than that required for the temperature detection element 436 installed on the carriage 434, so it is preferable to use the temperature detection element 436 installed on the carriage 434. In particular, when setting the ambient temperature Tamb by heating the platen heater 452, the time required for the temperature change of the temperature resistor 301 and temperature detection element 436, which are positioned opposite the platen heater 452, to stabilize is shorter than the time required for the temperature change of the temperature detection element 106, which is located in a position not corresponding to the platen heater 452, to stabilize. When using the temperature detection element 106, it is preferable to change the ambient temperature using a heater or air conditioning system installed in the room housing the liquid discharge device 400.

[0057] As described above, in this embodiment, calibration information CI is obtained using the difference ΔT between the detected temperature Tats of the resistance thermometer 301 and the detected temperature Tref of the temperature detection element 436 under multiple ambient temperatures, and the detected temperature Tats of the head tip is corrected using this calibration information CI. As a result, temperature detection can be performed with high accuracy by compensating for the change over time of the resistance thermometer 301 without using any special equipment for temperature calibration other than the liquid dispensing device 400.

[0058] Other forms: This disclosure is not limited to the embodiments described above, and can be implemented in various forms without departing from its spirit. For example, this disclosure can also be implemented in the following forms (aspects). The technical features in the embodiments described above that correspond to the technical features in each of the forms described below can be replaced or combined as appropriate in order to solve some or all of the problems of this disclosure, or to achieve some or all of the effects of this disclosure. Furthermore, if such technical features are not described as essential in this specification, they can be deleted as appropriate.

[0059] (1) According to a first embodiment of the present disclosure, a method is provided for detecting the temperature of a head tip in a liquid dispensing device having a head tip including a plurality of nozzles for dispensing liquid, using a resistance thermometer provided on the head tip. This method comprises: (a) determining a first detection temperature of the head tip using the resistance thermometer under a plurality of ambient temperatures, and determining a second detection temperature using a temperature detection element provided on the liquid dispensing device; (b) obtaining calibration information for calibrating the temperature detected by the resistance thermometer using the difference between the first detection temperature and the second detection temperature under the plurality of ambient temperatures; and (c) determining the detection temperature of the head tip using the resistance thermometer, and correcting the detection temperature of the head tip using the calibration information. This method allows for accurate temperature detection by compensating for changes in the resistance thermometer over time, without the need for special equipment for temperature calibration.

[0060] (2) In the above method, step (b) may include (b1) a step of determining the amount of change over time of the difference by subtracting a pre-registered initial difference from the difference between the first detected temperature and the second detected temperature under the plurality of ambient temperatures, and (b2) a step of creating calibration information to compensate for the amount of change over time. This method creates calibration information to compensate for the change over time in the difference between the first detected temperature and the second detected temperature, thereby compensating for the change over time in the resistance thermometer and enabling accurate temperature detection.

[0061] (3) In the above method, the plurality of ambient temperatures may include a first temperature which is room temperature and a second temperature which is raised above room temperature by a heater provided in the liquid dispensing device. This method makes it easy to achieve multiple ambient temperatures.

[0062] (4) In the above method, the plurality of ambient temperatures may include a first temperature raised above room temperature by a heater provided in the liquid dispensing device, and a second temperature raised above the first temperature by the heater. This method makes it easy to achieve multiple ambient temperatures.

[0063] (5) In the above method, the liquid dispensing device may be provided with a platen facing the nozzle surface through which the plurality of nozzles open and supporting a medium to which the liquid dispensed from the head tip lands, and the heater may be a platen heater provided on the platen. This method allows for achieving multiple ambient temperatures using a platen heater.

[0064] (6) In the above method, the temperature detection element may be provided facing the platen. This method allows for the creation of multiple ambient temperatures using a platen heater, and also enables the stabilization of the ambient temperatures of the temperature sensing element and resistance thermometer in a relatively short time.

[0065] (7) In the above method, steps (a) and (b) may be performed after the liquid dispensing device has been started and before the liquid dispensing process in which the liquid is dispensed, and step (c) may be performed during or after the liquid dispensing process. This method allows calibration information to be obtained before the liquid dispensing process, and this calibration information can be used to accurately determine the detected temperature of the head tip during and after the liquid dispensing process.

[0066] (8) A second embodiment of the present disclosure provides a liquid dispensing device for dispensing liquid. The liquid dispensing device includes a head tip including a plurality of nozzles for dispensing the liquid, a resistance thermometer provided on the head tip, a temperature detection element provided separately from the resistance thermometer, and a temperature detection correction unit for correcting the temperature detected on the head tip using the resistance thermometer. The temperature detection correction unit is configured to perform the following: (a) a process of determining a first temperature of the head tip using the resistance thermometer and determining a second temperature using the temperature detection element under a plurality of ambient temperatures; (b) a process of determining calibration information for calibrating the temperature detected by the resistance thermometer using the difference between the first and second temperature under the plurality of ambient temperatures; and (c) a process of determining the temperature of the head tip using the resistance thermometer and correcting the temperature of the head tip using the calibration information. This liquid dispensing device allows for accurate temperature detection by compensating for changes in the resistance thermometer over time, without the need for special equipment for temperature calibration.

[0067] This disclosure can also be implemented in various forms other than a method for detecting the temperature of a head chip or a liquid ejection device. For example, it can be implemented in the form of a method for correcting a common drive signal, a method for controlling a liquid ejection device, a computer program for implementing the method, and a non-temporary recording medium on which the computer program is stored. [Explanation of Symbols]

[0068] 50…Wiring board, 71,72…Drive circuit, 80…Piezoelectric element, 81…First electrode, 82…Second electrode, 83…Piezoelectric body, 84…Drive wiring, 100…Liquid discharge head, 101,102…Head chip, 106…Temperature sensing element, 120…Nozzle plate, 130…Sealing film, 140…Communicating plate, 150…Pressure chamber substrate, 160…Housing section, 170…Diaphragm, 200…Nozzle, 210…Common liquid chamber, 220…Nozzle-specific flow path, 230…Pressure chamber, 301, 302…Resistance thermometer, 310…Temperature detection circuit, 400…Liquid dispensing device, 410…Liquid storage unit, 420…Control unit, 421…Control signal supply unit, 422…Drive waveform correction unit, 423…Drive waveform storage unit, 424, 425…Drive signal generation unit, 426…Detected temperature correction unit, 430…Moving mechanism, 432…Belt, 434…Carriage, 436…Temperature detection element, 440…Conveying mechanism, 450…Platen, 452…Platen heater

Claims

1. A method for detecting the temperature of a head tip in a liquid dispensing device having a head tip including a plurality of nozzles for dispensing liquid, using a resistance thermometer provided on the head tip, (a) A step of determining the first detection temperature of the head chip using the resistance thermometer under multiple ambient temperatures, and determining the second detection temperature using the temperature detection element provided in the liquid dispensing device, (b) A step of obtaining calibration information for calibrating the temperature detected by the resistance thermometer using the difference between the first detected temperature and the second detected temperature under the plurality of ambient temperatures, (c) A step of determining the detected temperature of the head chip using the resistance thermometer and correcting the detected temperature of the head chip using the calibration information, A method for providing this.

2. The method according to claim 1, The above step (b) is, (b1) A step of determining the amount of change in the difference over time by subtracting a pre-registered initial difference from the difference between the first detected temperature and the second detected temperature under the plurality of ambient temperatures, (b2) A step of creating the calibration information so as to compensate for the amount of change over time, Methods that include...

3. The method according to claim 1, The method wherein the plurality of ambient temperatures include a first temperature which is room temperature and a second temperature which is raised above room temperature by a heater provided in the liquid dispensing device.

4. The method according to claim 1, The method wherein the plurality of ambient temperatures include a first temperature raised above room temperature by a heater provided in the liquid dispensing device, and a second temperature raised above the first temperature by the heater.

5. The method according to claim 3 or 4, The liquid dispensing device comprises a platen facing the nozzle surface through which the plurality of nozzles open, and supporting a medium upon which the liquid dispensed from the head tip lands. The method wherein the heater is a platen heater provided on the platen.

6. The method according to claim 5, The method wherein the temperature sensing element is provided opposite the platen.

7. The method according to claim 1, The steps (a) and (b) described above are performed after the liquid dispensing device has been started and before the liquid dispensing process in which the liquid is dispensed. Step (c) is a method performed during or after the liquid discharge process.

8. A liquid dispensing device that dispenses liquid, A head tip including a plurality of nozzles for dispensing the aforementioned liquid, A temperature-measuring resistance element provided on the head chip, A temperature detection element is provided separately from the aforementioned resistance thermometer, A detection temperature correction unit that corrects the detected temperature of the head chip detected using the resistance thermometer, Equipped with, The detected temperature correction unit is, (a) A process to determine the first detected temperature of the head chip using the resistance thermometer and the second detected temperature using the temperature detection element under multiple ambient temperatures, (b) A process to obtain calibration information for calibrating the temperature detected by the resistance thermometer using the difference between the first detected temperature and the second detected temperature under the plurality of ambient temperatures, (c) A process to determine the detected temperature of the head chip using the resistance thermometer and to correct the detected temperature of the head chip using the calibration information, A liquid dispensing device configured to perform the following actions.

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