Liquid dispensing head and liquid dispensing device

Abstract

To provide a liquid discharge device that can efficiently detect a temperature.SOLUTION: A liquid discharge head comprises a wiring substrate, an infrared temperature sensor, a heating element and a reflection board. The wiring substrate forms a driving circuit. The infrared temperature sensor is mounted on the wiring substrate. The reflection board is oppositely arranged in the heating element, which reflects infrared eradiated from the heating element toward the infrared temperature sensor.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] Embodiments of the present invention relate to a liquid ejection head and a liquid ejection device.

Background Art

[0002] Conventionally, a liquid ejection device having a liquid ejection head for ejecting a liquid has been known. The liquid ejection head has a heating element that easily generates heat. Such heating elements include, for example, electrical components and actuators. Examples of the electrical component include an IC mounted on a film such as a COF or the like. As a method for detecting the temperature of such a heating element, there is a method of mounting a thermistor or an infrared temperature sensor using a wire harness on a wiring board of a drive circuit.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] The problem to be solved by the present invention is to provide a liquid ejection device capable of efficiently detecting temperature.

Means for Solving the Problems

[0005] The liquid ejection head of the embodiment includes a wiring board, an infrared temperature sensor, a heating element, and a reflector. The wiring board forms a drive circuit. The infrared temperature sensor is mounted on the wiring board. The reflector is disposed opposite to the heating element and reflects infrared rays radiated from the heating element to the infrared temperature sensor.

Brief Description of the Drawings

[0006] [Figure 1] A block diagram showing the configuration of a liquid dispensing device according to the embodiment. [Figure 2] A schematic diagram showing the configuration of a liquid dispensing head according to an embodiment. [Figure 3] A schematic diagram showing the configuration of a liquid dispensing head according to another embodiment. [Figure 4] A schematic diagram showing the configuration of a liquid dispensing head according to another embodiment. [Figure 5] A schematic diagram showing the configuration of a liquid dispensing head according to another embodiment. [Figure 6] A schematic diagram showing the configuration of a liquid dispensing head according to another embodiment. [Modes for carrying out the invention]

[0007] The liquid discharge head 10 and liquid discharge device 1 according to the embodiment will be described below with reference to Figures 1 and 2. Figure 1 is a block diagram showing the configuration of the liquid discharge device 1 according to the embodiment. Figure 2 is an explanatory diagram schematically showing the configuration of the liquid discharge head 10 used in the liquid discharge device 1.

[0008] As shown in Figure 1, the liquid ejection device 1 comprises, for example, a liquid ejection head 10, a liquid supply device 11, an interface 17, and a control board 18. The liquid ejection device 1 is, for example, an image forming apparatus such as an inkjet recording device that ejects ink as a liquid. The liquid ejection device 1 may also be an inspection device used for shipping inspections such as operational verification tests and performance tests of the liquid ejection head 10 performed after the manufacturing of the liquid ejection head 10. The liquid ejection device 1 may have a configuration having multiple liquid ejection heads 10 and multiple liquid supply devices 11 so that different inks can be ejected.

[0009] The liquid dispensing device 1 includes, for example, a transport device for moving the recording medium along a transport path that includes a printing position facing the liquid dispensing head 10, a maintenance device for maintaining the liquid dispensing head 10, and various sensors and adjustment devices.

[0010] The liquid ejection head 10 is, for example, an inkjet head that ejects ink as a liquid. The liquid ejection head 10 is connected to a liquid supply device 11, and ink is supplied from the liquid supply device 11. The liquid ejection head 10 may be, for example, a non-circulating head that is supplied with ink from the liquid supply device 11, or it may be a circulating head in which ink circulates between it and the liquid supply device 11.

[0011] The liquid ejection head 10 ejects ink to form a desired image on a recording medium positioned opposite it.

[0012] As shown in Figure 2, the liquid discharge head 10 comprises a manifold, a nozzle plate 22 with multiple nozzles, an actuator unit 23, a substrate 26, an infrared temperature sensor 27, one or more reflectors 28, and a cover 29. The liquid discharge head 10 also includes a supply pipe for supplying liquid and a recovery pipe for recovering liquid.

[0013] The manifold has a supply channel formed inside that supplies ink supplied from the liquid supply device 11 to the actuator unit 23, and a discharge channel for ink that passes through the actuator unit 23 and is discharged back to the liquid supply device 11. For example, if the liquid supply device 11 is configured to have a temperature control device that adjusts the temperature of the actuator unit 23 and the ink with temperature-controlled water, the manifold may also have a channel for temperature-controlled water.

[0014] The nozzle plate 22 is formed, for example, in the shape of a rectangular plate and is fixed to the actuator unit 23. The nozzle plate 22 has multiple nozzle rows in which multiple nozzles are arranged in one direction.

[0015] The actuator unit 23 is fixed to the manifold. Inside the actuator unit 23, a predetermined flow path is formed, for example, including a plurality of pressure chambers communicating with the nozzles of the nozzle plate 22 and a common chamber communicating with these plurality of pressure chambers. The actuator unit 23 includes actuators 231 facing each pressure chamber. The actuator 231 may have a piezoelectric element with grooves forming the pressure chambers, or it may have a diaphragm forming the pressure chambers and a piezoelectric element that displaces the diaphragm. For example, the piezoelectric element is made of a piezoelectric ceramic material such as PZT (lead zirconate titanate). The actuator 231 has electrodes formed on the piezoelectric element, and these electrodes are electrically connected to the substrate 26. Various configurations can be applied to the actuator 231 as long as it is electrically connected to the substrate 26 and driven by a drive signal output from the substrate 26.

[0016] The supply pipe and recovery pipe are provided, for example, in the manifold. The supply pipe and recovery pipe are connected to the supply channel and discharge channel of the manifold, respectively. The supply pipe and recovery pipe are connected to the liquid supply device 11. The supply pipe and recovery pipe comprise a pipe made of metal or other thermally conductive material and a tube, such as a PTFE tube, covering the outer surface of the pipe. The manifold, actuator unit 23, supply pipe and recovery pipe form a flow path for the ink supplied from the liquid supply device 11 into the liquid discharge head 10.

[0017] The circuit board 26 is electrically connected to the actuator 231 of the actuator unit 23. The circuit board 26 is also connected to the control board 18 via a harness or the like. One or more circuit boards 26 are provided for each actuator 231, for example. As a specific example of one circuit board 26 being provided for each actuator 231, the liquid discharge head 10 has four rows of nozzles, four actuators 231 corresponding to each nozzle row, and four circuit boards 26 corresponding to each actuator 231.

[0018] The substrate 26 has one end connected to the actuator 231 of the actuator unit 23 and the other end connected to the control substrate 18 via a harness. As shown in FIG. 2, the substrate 26 includes, for example, a wiring film 261, a driving IC 262 mounted on the wiring film 261, and a printed circuit board 263 mounted on the wiring film 261.

[0019] The substrate 26 drives the actuator 231 by applying a driving voltage generated by the driving IC 262 to the actuator 231, increases or decreases the volume of the pressure chamber, and discharges droplets from the nozzle.

[0020] The wiring film 261 is a film substrate formed in a so-called film shape and having a wiring pattern formed of a metal material with high thermal conductivity, such as copper. The wiring film 261 is, for example, a COF (Chip on Film) on which the driving IC 262 is mounted. One or more wiring films 261 are provided for, for example, one actuator 231. In the present embodiment, an example in which one wiring film 261 is provided for one actuator 231 will be described.

[0021] The driving IC 262 is electrically connected to an electrode formed in the pressure chamber via the wiring film 261. The driving IC 262 is a heating element that generates heat. The driving IC 262 is mounted, for example, on the outer surface of the wiring film 261.

[0022] One driving IC 262 is provided for one wiring film 261. Note that a plurality of driving ICs 262 may be provided to drive one actuator 231, and these plurality of driving ICs 262 may be provided on one wiring film 261 to form a driving IC row. Further, for example, heat dissipation fins 265 are provided on the driving IC 262.

[0023] The heat dissipation fins 265 contact the surface of the wiring film 261 of the driving IC 262 opposite to the mounting surface and are fixed to the driving IC 262 and / or the wiring film 261.

[0024] The printed circuit board 263 is a wiring board for head driving that is connected to the drive IC 262. The printed circuit board 263 is, for example, a multilayer board. The printed circuit board 263 is connected to the actuator 231 via the drive IC 262. The printed circuit board 263 is a Printing Wiring Assembly (PWA) on which various electronic components and connectors are mounted. The printed circuit board 263 is, for example, formed in the shape of a rectangular plate, with one end of the wiring film 261 mounted on one side of one of its main surfaces. The mounting area on the printed circuit board 263 on which the wiring film 261 is mounted is, for example, formed in the shape of a rectangle that is long in one direction along the extending direction of one side of the printed circuit board 263. The printed circuit board 263 also includes an interface connector 267 mounted on a part of its outer surface.

[0025] For example, one end of a harness for connecting the control board 18 and the printed circuit board 263 is inserted into the interface connector 267.

[0026] Such a substrate 26, along with a wiring film 261, a drive IC 262, and a printed circuit board 263, constitutes a head drive circuit (drive circuit) that drives the liquid discharge head 10.

[0027] The infrared temperature sensor 27 detects radiant heat. The infrared temperature sensor 27 measures the temperature of the object to be measured from the incident infrared energy. The infrared temperature sensor 27 detects the temperature of any heat-generating element mounted on the liquid discharge head 10. The infrared temperature sensor 27 is mounted on a printed circuit board 263. For example, the infrared temperature sensor 27 is mounted on a surface of the printed circuit board 263 to which infrared energy emitted from the heat-generating element can be incident. The responsiveness of such an infrared temperature sensor 27 changes depending on the angle of incidence of the infrared energy, and the closer the angle of incidence is to vertical, the higher the responsiveness and the more accurate the temperature can be detected.

[0028] The infrared temperature sensor 27 is electrically connected to, for example, the interface connector 267 via the wiring pattern on the printed circuit board 263. The infrared temperature sensor 27 outputs a signal corresponding to the detected temperature to the control board 18 via the harness connected to the interface connector 267.

[0029] The reflector 28 is made of a material that easily reflects infrared energy. The reflector 28 is positioned opposite the heating element. For example, the reflector 28 is positioned opposite the heating element in the direction of radiation of the infrared energy emitted from the heating element. In a configuration in which multiple reflectors 28 are provided, one of the reflectors 28 is positioned opposite the heating element.

[0030] One or more reflectors 28 reflect infrared energy radiated from the heating element to the infrared temperature sensor 27. The number and arrangement of the reflectors 28 are set such that, for example, the angle of incidence and response of the infrared energy to the infrared temperature sensor 27 are suitable for the distance and arrangement of the heating element and the infrared temperature sensor 27, so that infrared energy can be reflected from the heating element to the infrared temperature sensor 27. The number, arrangement, and angle of the reflectors 28 are preferably such that, for example, the angle of incidence of the infrared energy to the infrared temperature sensor 27 is perpendicular or nearly perpendicular.

[0031] In the example shown in Figure 2, two reflectors 28 are provided. One of the two reflectors 281 is provided, for example, on the cover 29 and is positioned facing the drive IC 262, which is a heat-generating element, in one direction. The other of the two reflectors 282 is provided, for example, on the cover 29 and is positioned facing the infrared temperature sensor 27 in the same direction as the opposing direction of the one reflector 281 and the drive IC 262. The one reflector 281 and the other reflector 282 are positioned side by side in a direction perpendicular to the opposing direction of the one reflector 281 and the drive IC 262. The reflective surfaces of the one reflector 281 and the other reflector 282 are inclined, for example, at 45° with respect to the opposing direction of the one reflector 281 and the drive IC 262.

[0032] With this configuration, as shown by the dashed arrow I in Figure 2, the infrared energy I emitted from the drive IC 262 in the direction opposite to one reflector 281 and the drive IC 262 is reflected by one reflector 281. The infrared energy I reflected by one reflector 281 is then reflected by the other reflector 282 and incident on the infrared temperature sensor 27 at an angle of incidence that is vertical or nearly vertical.

[0033] The cover 29 covers the actuator unit 23, the substrate 26, and the infrared temperature sensor 27. The cover 29 covers the drive IC 262, for example, directly or indirectly via the wiring film 261, and faces the drive IC 262. One or more reflectors 28 are fixed to the inner surface of the cover 29.

[0034] A harness is, for example, a strip-shaped wiring board that is flexible and has a certain width. A harness is a so-called flexible cable. A harness contains multiple signal lines, which are wiring patterns that extend along the longitudinal direction of the harness. A harness is, for example, an FPC (Flexible Printed Circuit).

[0035] The liquid supply device 11 includes, for example, an ink tank, piping, and a pump 16.

[0036] The ink tank is a liquid storage unit that contains liquid such as ink supplied to the liquid ejection head 10. The ink tank is connected to the liquid ejection head 10 via piping. The ink tank is equipped with a temperature control device, which consists of, for example, heat dissipation fins, a heater, and a heat exchange module. The temperature control device heats or cools the ink in the ink tank to adjust the ink temperature. The piping forms a flow path connecting the liquid ejection head 10 and the ink tank. Filters and air traps are provided on the piping, for example.

[0037] Pump 16 is installed in the piping. Pump 16 supplies liquid from the ink tank to the liquid discharge head 10 via the piping by supplying liquid to the secondary side. Pump 16 is, for example, a piezoelectric pump. Pump 16 is connected to the drive circuit by wiring, for example, and is controlled by a processor 35 provided on the control board 18.

[0038] Interface 17 comprises a power supply 171, a display device 172, and an input device 173. Interface 17 is connected to a processor 35, which acts as a control unit. Interface 17 allows the user to operate the input device 173 to give instructions to the processor 35 for various operations. Interface 17 also displays various information and images on the display device, for example, under the control of the processor 35 on the control board 18.

[0039] The control board 18 is a control device. As shown in Figure 1, the control board 18 includes a processor 35, which is a control unit that controls the operation of each part; a memory 36 that stores programs and various data; and an AD conversion unit 37, which is a circuit that converts analog data (voltage values) into digital data (bit data). The control board 18 also includes various control circuits and drive circuits that control and drive each element.

[0040] The processor 35 includes, for example, a CPU (Central Processing Unit) and corresponds to the central part of the control unit. The processor 35 controls each part of the liquid dispensing device 1 in order to realize various functions of the liquid dispensing device 1 according to the operating system and application programs.

[0041] The processor 35 controls the head drive circuit, which is composed of the drive IC 262 for the liquid discharge head 10. The processor 35 is connected to various drive mechanisms and controls the operation of each part of the liquid discharge device 1 via various control circuits and drive circuits, such as the AD conversion unit 37, the liquid discharge head 10, and the head power supply circuit. The processor 35 also executes control processing based on a control program pre-recorded in the memory 36. For example, the processor 35 controls the printing operation by controlling the operation of the liquid discharge head 10 and the pump 16. The processor 35 applies a drive voltage to the electrodes of the actuator 231 via the drive IC 262. When a drive voltage is applied to the electrodes, the actuator deforms and discharges the liquid in the pressure chamber from the nozzle.

[0042] Furthermore, the processor 35 performs error detection processing for temperature abnormalities of the heating element and error management processing when an error is detected, based on the signal output from the infrared temperature sensor 27 and thresholds previously recorded in the memory 36. For example, the threshold used in the error detection processing is the temperature of abnormal heating of the heating element, and is stored in the memory 36 in advance, depending on the type of heating element. For example, as part of the error management processing, the processor 35 outputs a signal to the display device 172 of the interface 17 to display information about the temperature abnormality of the drive IC 262 (heating element), and the display device 172 displays the temperature abnormality of the drive IC 262. Alternatively, as part of the error management processing, the processor 35 may stop the operation of the actuator 231 when a temperature abnormality occurs in the drive IC 262.

[0043] The memory 36 is, for example, a non-volatile memory and is mounted on the control board 18. The memory 36 stores various control programs and operating conditions as information necessary for control such as ink circulation operation, ink supply operation, temperature control, liquid level control, pressure control, voltage control of the power supply required for controlling the liquid ejection head 10, error detection processing of the heat-generating element, and error management processing.

[0044] With the liquid discharge head 10 and liquid discharge device 1 configured in this way, the reflector 28 is positioned opposite the drive IC 262, which is a heat-generating element. The infrared energy I emitted from the heat-generating element is reflected by one or more reflectors 28 and incident on the infrared temperature sensor 27. Therefore, even if the infrared temperature sensor 27 and the drive IC 262 are not facing each other in a direction into which the infrared energy I of the infrared temperature sensor 27 can incident, the infrared temperature sensor 27 can efficiently measure the temperature of the drive IC 262.

[0045] Furthermore, the distance between the drive IC 262 and the infrared temperature sensor 27, and the angle at which infrared energy I is incident on the infrared temperature sensor 27, can be suitably set by the number, arrangement, and angle of the reflectors 28. As a result, infrared energy I is incident on the infrared temperature sensor 27 with high responsiveness, so the liquid discharge head 10 can measure the temperature of the drive IC 262 with high accuracy.

[0046] Furthermore, because the temperature of the drive IC 262 can be measured with high precision, abnormal heat generation of the drive IC 262, which is performed by the control board 18, can be detected with high precision. As a result, the liquid discharge head 10 can prevent damage to the drive IC 262 and can also notify the outside of the abnormal heat generation of the drive IC 262.

[0047] The liquid discharge head 10 and liquid discharge device 1 according to the above embodiment can efficiently detect temperature by positioning a reflector 28, which reflects the infrared energy I emitted by the drive IC 262 (a heat-generating element) to the infrared temperature sensor 27, opposite the drive IC 262.

[0048] It should be noted that the embodiments are not limited to the configuration described above. In the example described above, the liquid discharge head 10 was shown to have two reflectors 28, but it is not limited to this. For example, as in the other embodiment shown in Figure 3, the liquid discharge head 10 may have a configuration with only one reflector 28.

[0049] In other words, the distance and arrangement between the heating element and the infrared temperature sensor 27, as well as the number of reflectors 28, are set within a range where the responsiveness of the infrared temperature sensor 27 is not impaired by the infrared energy I emitted from the heating element. That is, since the responsiveness of the infrared temperature sensor 27 changes depending on the angle of incidence of the infrared energy I, if the distance between the infrared temperature sensor 27 and the drive IC 262 is within a range where this responsiveness is not impaired, one reflector may suffice, while conversely, if the distance is such that the responsiveness is impaired, it is desirable to use two reflectors. Note that there may be three or more reflectors 28.

[0050] Furthermore, as in the other embodiment shown in Figure 4, for example, the temperature of the heating element can be efficiently detected by adjusting the distance and arrangement relationship between the heating element and the infrared temperature sensor 27, as well as the number of reflectors 28, and the arrangement of the infrared temperature sensor 27. As an example of such a configuration, as shown in Figure 4, the orientation of the printed circuit board 263 may be inclined with respect to the extension direction of the wiring film 261, or the extension direction of the wiring film 261 may be inclined with respect to the printed circuit board 263. In the example in Figure 4, the extension direction of the printed circuit board 263 is shown to be perpendicular to the extension direction of the wiring film 261.

[0051] Furthermore, although the above example describes a configuration in which the liquid discharge head 10 has the drive IC 262 mounted on the wiring film 261, it is not limited to this. For example, as in the liquid discharge head 10 of another embodiment shown in Figure 5, the drive IC 262 may be mounted on the printed circuit board 263.

[0052] In the liquid discharge head 10 shown in Figure 5, if the drive IC 262 is mounted on the printed circuit board 263, for example, the heat dissipation fins 265 may be mounted on the side of the printed circuit board 263 opposite to the side facing the reflector 28. For example, as shown in Figure 5, the printed circuit board 263 is provided with through-holes 266 in the area where the heat dissipation fins 265 are mounted, and a metal film 2661 made of a metal material with high thermal conductivity, such as copper, is provided on the inner surface and surrounding area of ​​these through-holes 266 by plating or the like. The reflector 28 then reflects the infrared energy I radiated from the metal film 2661 of the through-holes 266 to the infrared temperature sensor 27. As a result, even if the drive IC 262 is mounted on the printed circuit board 263, the temperature of the drive IC 262 can be efficiently measured by the infrared temperature sensor 27.

[0053] Another example of mounting the drive IC 262 on the printed circuit board 263 is to mount a heat sink fin 265 on the surface of the printed circuit board 263 facing the reflector 28. In this case, since the heat sink fin 265 provided on the drive IC 262 faces the reflector 28, the reflector 28 reflects the infrared energy I radiated from the heat sink fin 265 to the infrared temperature sensor 27, and the infrared temperature sensor 27 can detect the temperature of the heat sink fin 265. In this case, for example, the memory 36 may store a correction value for estimating the temperature of the drive IC 262 from the temperature of the heat sink fin 265 when performing error determination processing, and the processor 35 may determine abnormal heat generation of the drive IC 262 from the measured temperature of the heat sink fin 265, as well as the correction value and threshold.

[0054] Furthermore, although the above-described embodiments have shown the heat-generating element as the drive IC 262, the invention is not limited to this. For example, as in the other embodiment shown in Figure 6, the heat-generating element may be a component other than the drive IC 262, such as an electronic component 264 mounted on the printed circuit board 263. Alternatively, the heat-generating element may be another component, such as the actuator 231.

[0055] Furthermore, in each of the embodiments described above, one or more reflectors 28 are fixed to the cover 29, but the invention is not limited to this. For example, the reflectors 28 may be fixed to a frame or other components other than the cover 29, or one of the reflectors 28 may be fixed to the cover 29 and the other reflectors 28 may be fixed to something other than the cover 29.

[0056] Furthermore, the type, number, and arrangement of the heating elements, as well as the infrared temperature sensors 27, can be arbitrarily configured. When measuring the temperatures of different heating elements, the infrared temperature sensors 27 can be configured to be the same number as the heating elements. In addition, to improve the accuracy and redundancy of temperature detection of the heating elements, the temperature of a single heating element may be measured by multiple infrared temperature sensors 27.

[0057] Furthermore, if a single liquid discharge head 10 is provided with multiple actuator units 23 and / or substrates 26, each substrate 26 may be provided with an infrared temperature sensor 27 for detecting the temperature of the heating element. Note that one or more reflectors 28 may be provided on each heating element and infrared temperature sensor 27, or they may be shared by multiple heating elements and infrared temperature sensors 27.

[0058] Furthermore, while the examples described above show the liquid ejection device 1, liquid ejection head 10, and substrate 26 being used in inspection equipment and inkjet recording equipment, they are not limited to these applications. For example, they can also be used in 3D printers, industrial manufacturing machinery, and medical applications. In addition, the substrate 26 can be used in various devices as long as it is configured to detect the temperature of a heating element mounted on a film.

[0059] The liquid dispensing head and liquid dispensing device configured according to each embodiment described above can efficiently measure the temperature of the heating element by placing one or more reflectors facing the heating element and reflecting the infrared energy to an infrared temperature sensor.

[0060] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. [Explanation of Symbols]

[0061] 1...Liquid dispensing device, 10...Liquid dispensing head, 11...Liquid supply device, 16...Pump, 17...Interface, 18...Control board (control device), 22...Nozzle plate, 23...Actuator unit, 26...Substrate, 27...Infrared temperature sensor, 28...Reflector, 29...Cover, 35...Processor, 36...Memory, 37...AD conversion unit, 171...Power supply, 172...Display device, 173...Input device, 231...Actuator, 261...Wiring film, 262...Drive IC (heating element), 263...Printed circuit board (wiring board), 264...Electronic component (heating element), 265...Heat sink fin, 266...Through hole, 267...Interface connector, 281...Reflector, 282...Reflector, 2661...Metal film, I...Infrared energy.

Claims

1. A wiring board that forms the drive circuit, An infrared temperature sensor mounted on the aforementioned wiring board, Heating element and A reflector is positioned opposite the heating element and reflects the infrared radiation emitted from the heating element to the infrared temperature sensor, A liquid dispensing head equipped with a liquid dispensing head.

2. The liquid dispensing head according to claim 1, wherein two reflectors are provided.

3. The liquid dispensing head according to claim 1, wherein the heating element is a drive IC. Liquid dispensing head.

4. Actuator and The actuator, the wiring board, the infrared temperature sensor, and the cover covering the drive IC, The liquid discharge head according to claim 3, comprising the reflector plate provided on the cover.

5. A liquid dispensing head according to any one of claims 1 to 4, A memory that stores the temperature of the abnormal heat generation of the aforementioned heating element as a threshold, A control device for determining abnormal overheating of the heating element based on the temperature of the heating element detected by the infrared temperature sensor and the threshold value, A liquid dispensing device equipped with the following features.

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