Warming device, image forming apparatus, and determination method

Abstract

The invention provides a heating device, an image forming apparatus, and a determination method capable of determining a decrease in a heating function. A heating device is provided with a coil pipe, a housing unit, a heater, a liquid level sensor, and a determination processing unit. The coil pipe has a spiral portion formed in a spiral shape. The accommodating part accommodates the spiral part and a liquid heat medium for heating the spiral part. The heater heats the accommodating part. The liquid level sensor detects the liquid level of the heat medium in the containing part. The determination processing unit determines, on the basis of the liquid level detected by the liquid level sensor, whether or not a heat medium shortage state is present in which the capacity of the heat medium in the storage unit is lower than a predetermined lower limit.

Description

Technical Field

[0001] The present invention relates to a heating device, an image forming device and a determination method. Background Art

[0002] An inkjet image forming apparatus is provided with a heating device for heating ink. For example, a heating device including a metal plate heated by a heater and a pipe arranged in contact with the metal plate is known.

[0003] However, by using a heat medium such as water instead of the metal plate, it is possible to suppress a rapid rise in the temperature of the ink in the heating device. For example, a structure including a coil disposed in a container filled with the heat medium and a heater for heating the container can be considered.

[0004] Here, in the above-mentioned structure, the storage capacity of the heat medium in the container may decrease due to evaporation or leakage. If the storage capacity of the heat medium in the container decreases, the heating function of the heating device to heat the ink decreases. Summary of the invention

[0005] An object of the present invention is to provide a warming device, an image forming device, and a determination method capable of determining a decrease in a warming function.

[0006] A heating device according to one aspect of the present invention comprises: a coil having a spiral portion formed in a spiral shape; a receiving portion receiving the spiral portion and a heat medium for heating a liquid in the spiral portion; a heater for heating the receiving portion; a liquid level sensor for detecting a liquid level of the heat medium in the receiving portion; and a determination processing portion for determining, based on a detection result of the liquid level sensor, whether a heat medium shortage state is reached in which a storage capacity of the heat medium in the receiving portion is lower than a predetermined lower limit.

[0007] An image forming apparatus according to another aspect of the present invention includes the heating device described above, and forms an image using ink heated by the heating device.

[0008] A determination method according to another aspect of the present invention is performed by a heating device, the heating device comprising: a coil having a spiral portion formed in a spiral shape; a receiving portion receiving the spiral portion and a heat medium for heating a liquid in the spiral portion; a heater for heating the receiving portion; and a liquid level sensor for detecting a liquid level of the heat medium in the receiving portion, the determination method comprising a determination step for determining, based on a detection result of the liquid level sensor, whether the heat medium in the receiving portion is in a heat medium shortage state in which the storage capacity of the heat medium is lower than a predetermined lower limit.

[0009] According to the present invention, it is possible to determine whether the warming function has declined.

[0010] This specification is presented in a simplified form, with appropriate reference to the accompanying drawings, to summarize the concepts described in the following detailed description. This specification is not intended to limit the important features and essential features of the subject matter described in the claims, nor is it intended to limit the scope of the subject matter described in the claims. In addition, the subject matter described in the claims is not limited to implementations that solve some or all of the disadvantages described in any part of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a diagram showing the structure of an image forming apparatus according to a first embodiment of the present invention.

[0012] Figure 2 It is a diagram showing the configuration of an image forming section and a transport unit of an image forming apparatus according to a first embodiment of the present invention.

[0013] Figure 3 This is a block diagram showing the system configuration of the image forming apparatus according to the first embodiment of the present invention.

[0014] Figure 4 It is a diagram showing a configuration of an ink supply unit of an image forming apparatus according to a first embodiment of the present invention.

[0015] Figure 5 It is a diagram showing the structure of a heating device of an image forming apparatus according to the first embodiment of the present invention.

[0016] Figure 6 This is a flowchart showing an example of the first operation control process executed in the image forming apparatus according to the first embodiment of the present invention.

[0017] Figure 7 This is a block diagram showing a system configuration of an image forming apparatus according to a second embodiment of the present invention.

[0018] Figure 8 It is a diagram showing a configuration of an ink supply unit of an image forming apparatus according to a second embodiment of the present invention.

[0019] Fig. 9 This is a flowchart showing an example of the second operation control process executed in the image forming apparatus according to the second embodiment of the present invention.

[0020] Fig.10 This is a block diagram showing a system configuration of an image forming apparatus according to a third embodiment of the present invention.

[0021] Fig.11 This is a flowchart showing an example of a third operation control process executed in the image forming apparatus according to the third embodiment of the present invention. DETAILED DESCRIPTION

[0022] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that the following embodiment is an example of embodying the present invention and does not limit the technical scope of the present invention.

[0023] [First embodiment] First, refer to Figure 1 to Figure 3 The structure of the image forming apparatus 100A according to the first embodiment of the present invention will be described. Figure 1 1 is a cross-sectional view showing the structure of the image forming apparatus 100A. Figure 2 3 is a top view showing the structure of the image forming unit 3 and the conveying unit 4. Figure 1 In FIG. 1 , the sheet conveyance path R11 is indicated by a two-dot chain line.

[0024] The image forming apparatus 100A is a printer capable of forming an image on a sheet by inkjet method. The present invention can also be applied to image forming apparatuses such as a facsimile machine, a copy machine, and a multifunction peripheral capable of forming an image on a sheet by inkjet method.

[0025] like Figure 1 and Figure 3 As shown, the image forming apparatus 100A includes a housing 1 , a sheet conveying unit 2 , an image forming unit 3 , a conveying unit 4 , an operation display unit 5 , a storage unit 6 , a control unit 7 , and an ink supply unit 8 .

[0026] The housing 1 accommodates the components of the image forming apparatus 100A. A paper feed cassette 11 is detachably provided in the housing 1. The paper feed cassette 11 accommodates sheets for image formation. A paper discharge tray 12 is provided on the outer side of the housing 1. The sheets on which the image is formed by the image forming unit 3 are discharged to the paper discharge tray 12. Inside the housing 1, the sheets accommodated in the paper feed cassette 11 are transported along a sheet transport path R11 (see FIG. 1 ). Figure 1 ) is transported, and the sheet transport path R11 reaches the paper discharge tray 12 via the image forming position of the image forming unit 3.

[0027] The sheet conveying unit 2 is arranged along a sheet conveying path R11 (see Figure 1 ) conveys the sheets stored in the paper feed cassette 11. Figure 1 As shown in FIG. 1 , the sheet conveying unit 2 includes a pickup roller 21 and a plurality of conveying rollers 22. The pickup roller 21 takes out the topmost sheet in the sheet stack stored in the paper feed cassette 11 and delivers the sheet to the sheet conveying path R11. The plurality of conveying rollers 22 are arranged along the sheet conveying path R11. Each conveying roller 22 conveys the sheet along the sheet conveying path R11. Each conveying roller 22 conveys the sheet in a conveying direction D11 (see FIG. 1 ) from the paper feed cassette 11 to the paper discharge tray 12. Figure 1 )delivery.

[0028] The image forming unit 3 forms an image on the sheet supplied from the sheet conveying unit 2 according to the image data. Figure 1 As shown, the image forming unit 3 includes line heads 31 to 34 and a head frame 35 .

[0029] like Figure 2 As shown, each line head 31 to 34 is long in the width direction D12 orthogonal to the conveying direction D11. Specifically, each line head 31 to 34 has a length in the width direction D12 corresponding to the width of the largest sheet that can be accommodated in the paper feed cassette 11. Each line head 31 to 34 is arranged at equal intervals along the conveying direction D11.

[0030] like Figure 2 As shown, each of the line heads 31 to 34 includes a plurality of recording heads 30. The recording heads 30 eject ink toward the sheet transported by the transport unit 4. Specifically, a plurality of nozzles 36 for ejecting the ink are provided on the surface of the recording head 30 that faces the sheet (see FIG. 4 ). Figure 2 ). The recording heads 30 provided in the line head 31 eject the black ink respectively. The recording heads 30 provided in the line head 32 eject the cyan ink respectively. The recording heads 30 provided in the line head 33 eject the magenta ink respectively. The recording heads 30 provided in the line head 34 eject the yellow ink respectively.

[0031] In this embodiment, the line head 31 has three recording heads 30 arranged in a staggered manner along the width direction D12. In addition, the other line heads 32 to 34 also have three recording heads 30 arranged in a staggered manner along the width direction D12, similarly to the line head 31. Figure 2 In the Figure 1 Observe the state of the image forming unit 3 from the upper side.

[0032] The head frame 35 supports the line heads 31 to 34. The head frame 35 is supported by the housing 1. The number of line heads provided in the image forming unit 3 may be one or more. The number of recording heads 30 provided in each of the line heads 31 to 34 may not be limited to three.

[0033] like Figure 1 As shown in FIG. 1 , the conveying unit 4 is disposed below the line heads 31 to 34. The conveying unit 4 makes the sheet face the recording head 30 and conveys the sheet. For example, each time the recording head 30 ejects the ink, the conveying unit 4 conveys the sheet by a predetermined amount. In addition, during the period when the recording head 30 ejects the ink, the conveying unit 4 stops conveying the sheet. Figure 1As shown, the conveying unit 4 includes: a conveying belt 41 for carrying a sheet; a first tensioning roller 42, a second tensioning roller 43, and a third tensioning roller 44 for tensioning the conveying belt 41; and a conveying frame 45 for supporting them. In addition, the gap between the conveying belt 41 and the recording head 30 is adjusted so that the gap between the surface of the sheet and the recording head 30 during image formation becomes a predetermined distance (for example, 1 mm).

[0034] The first tension roller 42 is driven to rotate by a rotational driving force supplied by a motor (not shown). Figure 1 ) is rotated in the conveying direction. In addition, the conveying unit 4 is also provided with a suction unit (not shown) that sucks air from a plurality of through holes formed in the conveying belt 41 to adsorb the sheet to the conveying belt 41. In addition, a pressing roller 46 for pressing the sheet against the conveying belt 41 and conveying it is provided on the upper side of the first tensioning roller 42.

[0035] The operation display unit 5 is a user interface of the image forming apparatus 100A. The operation display unit 5 includes a display unit and an operation unit. The display unit displays various information according to control instructions from the control unit 7. For example, the display unit is a liquid crystal display. The operation unit inputs various information to the control unit 7 according to user operations. For example, the operation unit is a touch panel. The operation display unit 5 is provided on the upper surface of the housing 1.

[0036] The storage unit 6 is a nonvolatile storage device. For example, the storage unit 6 is a nonvolatile memory such as a flash memory. Alternatively, the storage unit 6 may be an SSD (Solid State Drive) or an HDD (Hard Disk Drive).

[0037] The control unit 7 controls the image forming apparatus 100A in a unified manner. Figure 3 As shown, the control unit 7 includes a CPU 51, a ROM 52, and a RAM 53. The CPU 51 is a processor that performs various arithmetic operations. The ROM 52 is a non-volatile storage device that pre-stores information such as control programs for the CPU 51 to perform various processes. The RAM 53 is a volatile or non-volatile storage device used as a temporary memory (operating area) for various processes performed by the CPU 51. The CPU 51 uniformly controls the image forming apparatus 100A by executing various control programs pre-stored in the ROM 52. In addition, the control unit 7 may be a control unit that is separately provided from the main control unit that uniformly controls the image forming apparatus 100A. In addition, the control unit 7 may also be composed of an electronic circuit such as an integrated circuit (ASIC).

[0038] [Structure of the ink supply unit 8] Next, refer to Figure 4 The structure of the ink supply unit 8 is described below. Figure 4 In FIG. 6 , the first supply passage 62 and the second supply passage 66 are indicated by bold lines.

[0039] The ink supply unit 8 supplies the ink to the recording head 30. The ink supply unit 8 is provided for each recording head 30. The configurations of the plurality of ink supply units 8 corresponding to the line heads 31 to 34 are the same except that the colors of the inks supplied are different.

[0040] like Figure 4 As shown, the ink supply unit 8 includes an ink container 61 , a first supply channel 62 , a warming device 63 , a first pump 64 , an auxiliary ink cartridge 65 , a second supply channel 66 , and a second pump 67 .

[0041] The ink container 61 contains the ink. For example, the ink is an aqueous ink whose main solvent is water. Alternatively, the ink may be a non-aqueous ink whose main solvent is an organic solvent.

[0042] The first supply passage 62 is an ink flow path provided between the ink container 61 and the auxiliary ink cartridge 65. The first supply passage 62 is formed of a material having flexibility. For example, the first supply passage 62 is a tube made of resin.

[0043] The heating device 63 is provided in the first supply channel 62. The heating device 63 heats the ink flowing in the first supply channel 62. The image forming apparatus 100A forms an image using the ink heated by the heating device 63.

[0044] The first pump 64 is provided in the first supply channel 62. The first pump 64 causes the ink in the first supply channel 62 to flow in a direction D21 (see FIG. 21 ) toward the recording head 30. Figure 4 )flow.

[0045] The auxiliary ink cartridge 65 contains the ink supplied from the ink container 61. The ink contained in the auxiliary ink cartridge 65 is supplied to the recording head 30.

[0046] The second supply channel 66 is an ink flow channel provided between the auxiliary ink tank 65 and the recording head 30. The second supply channel 66 is formed of a flexible material. For example, the second supply channel 66 is a resin tube.

[0047] The second pump 67 is provided in the second supply channel 66. The second pump 67 causes the ink in the second supply channel 66 to flow in the direction D21 (refer to Figure 4 )flow.

[0048] In addition, the image forming apparatus 100A may not include the auxiliary ink cartridge 65 . That is, the recording head 30 may directly receive the supply of the ink from the ink container 61 .

[0049] [Structure of the heating device 63] Next, refer to Figure 5 The structure of the heating device 63 will be described. Figure 5 It is a cross-sectional view showing the structure of the heating device 63.

[0050] like Figure 5 As shown, the heating device 63 includes a flexible pipe 71 , a container 72 , a heater 73 , a heat insulating material 74 , a first temperature sensor 75 , and a second temperature sensor 76 .

[0051] The coiled tube 71 is a tube formed in a spiral shape. The coiled tube 71 is arranged in a posture where the spiral axis is along the vertical direction. For example, the coiled tube 71 is formed by processing a metal straight tube into a spiral shape. For example, the cross-sectional shape of the straight tube is a perfect circle, and the straight tube is made of stainless steel. In addition, the cross-sectional shape of the straight tube can also be an ellipse, etc.

[0052] like Figure 5 As shown, the coil 71 includes a first piping portion 81, a spiral portion 82, and a second piping portion 83. The first piping portion 81 extends in the vertical direction. The upper end of the first piping portion 81 is connected to the ink container 61 (see FIG. 6 ) through the first supply channel 62. Figure 4 The spiral portion 82 is formed in a spiral shape from the lower end of the first piping portion 81 toward the upper direction. The second piping portion 83 is formed from the upper end 84 of the spiral portion 82 (see Figure 5 The upper end of the second piping portion 83 is connected to the first pump 64 (see Figure 4 )connect.

[0053] The container 72 accommodates the spiral portion 82 of the bellows 71 and the liquid heat medium M1 for heating the spiral portion 82 (see Figure 5 ) The container 72 is an example of a storage unit of the present invention.

[0054] For example, the container 72 includes a cylindrical portion extending in the vertical direction, a disc-shaped bottom portion closing the lower end of the cylindrical portion, and a disc-shaped top plate portion closing the upper end of the cylindrical portion. The first piping portion 81 and the second piping portion 83 of the coiled tube 71 extend from the inside of the container 72 to the outside of the container 72 through holes formed in the top plate portion, respectively. In addition, the container 72 may not have the top plate portion. In addition, the container 72 is not limited to a cylindrical shape, and may also be formed in a hollow prism shape.

[0055] The interior of the container 72 is filled with a heat medium M1 in an amount sufficient to submerge the spiral portion 82 (see Figure 5 That is, in the container 72, the liquid level of the heat medium M1 is higher than the upper end 84 of the spiral portion 82 (see Figure 5 ) is located further up. For example, the heat medium M1 is water. In addition, the heat medium M1 is not limited to water, and may be a fluid such as oil.

[0056] The heater 73 heats the container 72. Specifically, the heater 73 is a so-called planar heater. For example, the heater 73 includes a heating wire and a metal sheet such as aluminum covering the heating wire. The heater 73 is provided so as to cover the outer surface of the container 72. In addition, the heater 73 may also be a silicone rubber heater or the like.

[0057] In the heating device 63, the container 72 is heated by the heater 73, thereby heating the heat medium M1 contained in the container 72. Thus, the ink flowing inside the spiral portion 82 is heated, and the spiral portion 82 is arranged in the heat medium M1. In the heating device 63, compared with a structure in which a metal plate is in contact with both the heater 73 and the pipe through which the ink flows and the heat of the heater 73 is transferred to the ink via the metal plate, a rapid increase in the temperature of the ink can be suppressed.

[0058] However, the closer the heat medium M1 in the container 72 is to the heater 73, the faster it is heated. That is, in the heating device 63, the temperature of the heat medium M1 is not uniform for a period of time after the heater 73 starts to be driven. When the temperature of the heat medium M1 is not uniform, the temperature of the ink heated by the heating device 63 is not stable.

[0059] In contrast, in the heating device 63 according to the first embodiment of the present invention, as described below, it is possible to shorten the time required for the temperature of the heating medium M1 to become uniform.

[0060] Specifically, the heater 73 heats a portion of the container 72 below the upper end portion 84 of the spiral portion 82 , and does not heat a portion above the upper end portion 84 .

[0061] That is, in the heating device 63, the upper portion including the liquid surface of the heat medium M1 contained in the container 72 is not heated by the heater 73. As a result, a temperature difference is generated between the upper portion and the lower portion of the heat medium M1 contained in the container 72, and convection is generated in the heat medium M1. Therefore, the time required for the temperature of the heat medium M1 to become uniform can be shortened. In addition, even if a structure for stirring the heat medium M1 is not provided, the time required for the temperature of the heat medium M1 to become uniform can be shortened.

[0062] For example, the heater 73 heats at least the bottom of the container 72 .

[0063] For example, the heater 73 heats a region AR1 (see FIG. 1 ) from the lower end portion of the cylindrical portion of the container 72 to a portion below the upper end portion 84 of the spiral portion 82. Figure 5 ). For example, the planar heater 73 is wound around the area AR1.

[0064] In addition, the heater 73 may heat a part of the cylindrical portion and the bottom surface of the bottom portion of the container 72. In addition, the heater 73 may heat only the bottom surface of the bottom portion of the container 72. In addition, the heater 73 may heat only a part of the upper side of the region AR1. That is, the heater 73 may not heat the bottom portion of the container 72.

[0065] The heat insulating material 74 is provided so as to cover the outer peripheral surface of the container 72. The heater 73 is provided between the container 72 and the heat insulating material 74. For example, the heat insulating material 74 is provided so as to cover the entire outer surface of the container 72.

[0066] The first temperature sensor 75 is disposed in the container 72 and is a contact temperature sensor for detecting the temperature of the heat medium M1. Figure 5 As shown, the first temperature sensor 75 is arranged at a position higher than the spiral portion 82 of the coil 71. In this case, the interior of the container 72 is filled with a heat medium M1 in an amount that submerges the first temperature sensor 75. For example, the first temperature sensor 75 is arranged on the inner side of the spiral portion 82. The first temperature sensor 75 outputs a first detection signal including a signal value corresponding to the temperature of the contacting heat medium M1. The first detection signal output from the first temperature sensor 75 is input to the control unit 7. In addition, the first temperature sensor 75 may also be arranged on the outer side of the spiral portion 82. In addition, the first temperature sensor 75 may also be arranged on the lower side than the upper end portion 84 of the spiral portion 82.

[0067] The second temperature sensor 76 is disposed outside the container 72 and is used to detect the temperature of the container 72. Figure 5 As shown, the second temperature sensor 76 is disposed between the heater 73 and the insulating material 74. The second temperature sensor 76 outputs a second detection signal including a signal value corresponding to the temperature of the container 72. The second detection signal output from the second temperature sensor 76 is input to the control unit 7. In addition, the second temperature sensor 76 may also be disposed so as to contact the outer surface of the container 72.

[0068] [Configuration of the control unit 7] Next, refer to Figure 3 The configuration of the control unit 7 will be described in more detail.

[0069] like Figure 3As shown, the control unit 7 includes a drive control unit 91, a stop processing unit 92, and an acquisition processing unit 93. The device including the control unit 7 and the heating device 63 is an example of the heating device of the present invention.

[0070] Specifically, a first operation control program for causing the CPU 51 to function as the above-mentioned functional units is stored in advance in the ROM 52 of the control unit 7. The CPU 51 functions as the above-mentioned functional units by executing the first operation control program stored in the ROM 52.

[0071] In addition, the first motion control program is stored in a computer-readable storage medium such as a CD, a DVD, and a flash memory, or can be read from the storage medium and stored in a storage device such as the storage unit 6. In addition, part or all of the above-mentioned functional units can also be composed of electronic circuits such as an integrated circuit (ASIC). In addition, the first motion control program can also be a program that enables multiple processors to function as the functional units included in the control unit 7.

[0072] The drive control unit 91 controls the drive of the heater 73 based on the first detected temperature detected by the first temperature sensor 75 .

[0073] Specifically, the drive control unit 91 controls the power supply to the heater 73 so that the first detected temperature detected by the first temperature sensor 75 becomes a predetermined target temperature. The target temperature is set according to the temperature of the ink suitable for printing. For example, the drive control unit 91 controls the drive of the heater 73 through PID control. For example, in the image forming device 100A, a switch element (not shown) capable of switching the conduction and disconnection of the power supply path is provided on the power supply path between the power supply not shown and the heater 73. The drive control unit 91 inputs a PWM signal with a duty ratio corresponding to the difference between the first detected temperature and the target temperature to the switch element to control the on-off of the switch element. Thus, the amount of power supplied to the heater 73 is adjusted according to the difference between the first detected temperature and the target temperature.

[0074] For example, when the image forming unit 3 is used to perform an image forming process for forming an image based on image data, the drive control unit 91 performs drive control of the heater 73. For example, in the image forming apparatus 100A, when the first detected temperature reaches the target temperature, the ink supply unit 8 starts supplying the ink and starts executing the image forming process.

[0075] However, in the heating device 63, the first temperature sensor 75 is disposed in the heat medium M1 that generates convection. That is, the first temperature sensor 75 is subjected to the flow of the heat medium M1. Therefore, in the heating device 63, the first temperature sensor 75 may have an abnormality such as a malfunction or poor contact. If the first temperature sensor 75 has such an abnormality, there is a risk that the drive control of the heater 73 becomes inoperative and the temperature of the heat medium M1 excessively rises.

[0076] On the other hand, in the heating device 63 according to the first embodiment of the present invention, as described below, it is possible to avoid an excessive increase in the temperature of the heat medium M1.

[0077] When the temperature of the container 72 exceeds a predetermined upper limit temperature, the stop processing unit 92 stops the driving of the heater 73. The stop processing unit 92 is an example of a stop unit of the present invention.

[0078] Specifically, when the second detected temperature detected by the second temperature sensor 76 exceeds the upper limit temperature, the stop processing unit 92 stops the driving of the heater 73. The upper limit temperature is a temperature higher than the target temperature.

[0079] Furthermore, the stop processing section 92 restricts execution of the image forming processing.

[0080] Here, the heating device 63 has Figure 5 Thermostat 77 is shown.

[0081] When the temperature of the container 72 exceeds a predetermined cutoff temperature, the thermostat 77 cuts off the power supply path of the heater 73 to stop the driving of the heater 73. For example, the thermostat 77 is provided on the outer surface of the container 72. Figure 5 As shown, the thermostat 77 is arranged at the same position as the first temperature sensor 75 in the vertical direction. The cut-off temperature is a temperature higher than the target temperature. For example, the cut-off temperature is a temperature higher than the upper limit temperature. The thermostat 77 is another example of the stop portion of the present invention. In addition, the cut-off temperature is another example of the upper limit temperature of the present invention. In addition, a temperature fuse may be used instead of the thermostat 77.

[0082] The acquisition processing unit 93 acquires the storage capacity of the heat medium M1 in the container 72 based on the rate of increase of the second detected temperature from the start of driving of the heater 73 .

[0083] For example, in the image forming apparatus 100A, table data in which the rising speed of the second detected temperature and the storage capacity of the heat medium M1 are associated with each other is stored in advance in the storage unit 6. In the table data, the correspondence between the rising speed of the second detected temperature and the storage capacity of the heat medium M1 is determined such that the faster the rising speed of the second detected temperature, the smaller the storage capacity of the heat medium M1. Alternatively, the table data can be created based on the results of an experiment in which the rising speed of the second detected temperature corresponding to each of a plurality of storage capacities of the heat medium M1 is measured.

[0084] For example, the acquisition processing unit 93 acquires the rate of increase of the second detected temperature based on the amount of increase of the second detected temperature from the start of driving of the heater 73 to the elapse of a predetermined specific time. Then, the acquisition processing unit 93 acquires the storage capacity of the heat medium M1 associated with the acquired rate of increase of the second detected temperature from the table data as the current storage capacity of the heat medium M1 in the container 72.

[0085] For example, when the acquisition processing unit 93 acquires the storage capacity of the heat medium M1 in the container 72 , the control unit 7 notifies the storage capacity. For example, the control unit 7 displays the storage capacity of the heat medium M1 in the container 72 acquired by the acquisition processing unit 93 on the operation display unit 5 .

[0086] In addition, when the amount of heat medium M1 in the container 72 acquired by the acquisition processing unit 93 is less than a predetermined lower limit, the control unit 7 may stop driving the heater 73 and notify the heat medium shortage state. The heat medium shortage state is a state in which the amount of heat medium M1 in the container 72 is less than the lower limit. The lower limit is when the liquid level of the heat medium M1 is Figure 5 The storage capacity of the heat medium M1 in the container 72 at the lower limit position P1 shown in FIG. The lower limit position P1 is a position below the first temperature sensor 75 and above the upper end 84 of the spiral portion 82. Figure 5 , the lower limit position P1 is indicated by a single-dot chain line.

[0087] Alternatively, the control unit 7 may notify the storage capacity only when the storage capacity of the heat medium M1 in the container 72 acquired by the acquisition processing unit 93 is greater than the lower limit amount and less than a predetermined amount.

[0088] [First motion control process] Below, refer to Figure 6An example of the sequence of the first motion control process executed by the control unit 7 in the image forming apparatus 100A is described. Here, steps S11, S12, ... represent the numbers of the process sequence (steps) executed by the control unit 7. The first motion control process is executed when the drive control unit 91 starts the drive control of the heater 73.

[0089] <Step S11> First, in step S11, the control unit 7 obtains the storage capacity of the heat medium M1 in the container 72 based on the rising rate of the second detected temperature from the start of driving the heater 73. Here, the process of step S11 is executed by the acquisition processing unit 93 of the control unit 7.

[0090] Specifically, the control unit 7 obtains the rising speed of the second detected temperature based on the rising amount of the second detected temperature from the start of driving of the heater 73 to the elapse of the specific time. Then, the control unit 7 obtains the storage capacity of the heat medium M1 associated with the obtained rising speed of the second detected temperature from the table data as the current storage capacity of the heat medium M1 in the container 72.

[0091] <Step S12> In step S12 , the control unit 7 notifies the storage capacity of the heat medium M1 in the container 72 acquired in the process of step S11 .

[0092] Specifically, the control unit 7 displays the storage capacity of the heat medium M1 in the container 72 acquired by the process of step S11 on the operation display unit 5. Thus, the user of the image forming apparatus 100A can determine whether the heat medium M1 needs to be replenished.

[0093] <Step S13> In step S13 , the control unit 7 determines whether the first detected temperature detected by the first temperature sensor 75 reaches the target temperature.

[0094] Here, if it is determined that the first detected temperature has reached the target temperature ("Yes" side of S13), the control unit 7 ends the first action control process. In addition, if the first detected temperature has not reached the target temperature ("No" side of S13), the control unit 7 transfers the process to step S14.

[0095] <Step S14> In step S14 , the control unit 7 determines whether the second detected temperature detected by the second temperature sensor 76 exceeds the upper limit temperature.

[0096] Here, if it is determined that the second detected temperature exceeds the upper limit temperature ("Yes" side of S14), the control unit 7 transfers the process to step S15. In addition, if the second detected temperature does not exceed the upper limit temperature ("No" side of S14), the control unit 7 transfers the process to step S13.

[0097] <Step S15> In step S15, the control unit 7 stops driving the heater 73. In addition, the control unit 7 limits execution of the image forming process. Here, the process of step S15 is executed by the stop processing unit 92 of the control unit 7.

[0098] <Step S16> In step S16, the control unit 7 notifies that the driving of the heater 73 is stopped due to the occurrence of the abnormality or the insufficient state of the heat medium. Thus, the user of the image forming apparatus 100A can take measures such as resolving the abnormality or replenishing the heat medium M1.

[0099] Thus, in the image forming apparatus 100A, the portion of the container 72 below the upper end portion 84 of the spiral portion 82 is heated, and the portion above the upper end portion 84 is not heated. As a result, a temperature difference is generated between the upper portion and the lower portion of the heat medium M1 contained in the container 72, and convection is generated in the heat medium M1. Therefore, the time required for the temperature of the heat medium M1 to become uniform can be shortened.

[0100] However, in the image forming apparatus 100A, the storage capacity of the heat medium M1 in the container 72 may decrease due to evaporation or leakage. If the storage capacity of the heat medium M1 in the container 72 decreases, the heating function of the heating device 63 to heat the ink decreases.

[0101] On the other hand, in the image forming apparatus 100B according to the second embodiment of the present invention, it is possible to determine the decline of the warming function as described below.

[0102] [Second embodiment] Next, refer to Figure 7 and Figure 8 The configuration of an image forming apparatus 100B according to a second embodiment of the present invention will be described.

[0103] The image forming apparatus 100B is different from the image forming apparatus 100A in the configurations of the control unit 7 and the ink supply unit 8. The other configurations are common to the image forming apparatus 100A and the image forming apparatus 100B. Only the configurations of the image forming apparatus 100B that are different from the image forming apparatus 100A will be described below.

[0104] like Figure 8As shown, the ink supply unit 8 of the image forming apparatus 100B further includes a heat medium storage unit 85 , a heat medium supply passage 86 , and a third pump 87 .

[0105] The heat medium storage portion 85 stores the heat medium M1.

[0106] The heat medium supply passage 86 is a flow passage of the heat medium M1 provided between the heat medium storage section 85 and the container 72 of the heating device 63. The heat medium supply passage 86 is formed of a flexible material. For example, the heat medium supply passage 86 is a resin pipe.

[0107] The third pump 87 is provided in the heat medium supply passage 86 . The third pump 87 causes the heat medium M1 in the heat medium supply passage 86 to flow toward the heating device 63 side.

[0108] like Figure 7 As shown, the control unit 7 includes a drive control unit 91, a determination processing unit 94, a first notification processing unit 95, and a supply processing unit 96. The device including the control unit 7 and the heating device 63 is another example of the heating device of the present invention.

[0109] Specifically, a second motion control program for causing the CPU 51 of the control unit 7 to function as the above-mentioned functional units is stored in advance in the ROM 52 of the control unit 7. The CPU 51 of the control unit 7 functions as the above-mentioned functional units by executing the second motion control program stored in the ROM 52.

[0110] The function of the drive control section 91 is the same as that of the drive control section 91 included in the image forming apparatus 100A.

[0111] The determination processing unit 94 determines whether the heat medium M1 storage amount in the container 72 is in the heat medium shortage state below the lower limit amount based on the first detected temperature after the start of driving the heater 73 .

[0112] For example, when the amount of increase in the first detected temperature from the start of driving of the heater 73 to the elapse of a predetermined reference time is equal to or less than a predetermined threshold, the determination processing unit 94 determines that the heat medium is insufficient.

[0113] When the determination processing unit 94 determines that the heat medium is insufficient, the first notification processing unit 95 notifies the user of the state.

[0114] For example, the first notification processing unit 95 causes the operation display unit 5 to display a message indicating the heat medium shortage state.

[0115] Furthermore, the first notification processing section 95 restricts execution of the image forming process.

[0116] In the image forming apparatus 100B, even after the heat medium shortage state is determined, the drive control unit 91 continues to drive and control the heater 73 so as to determine whether the heat medium shortage state is resolved by supplying the heat medium M1 .

[0117] When the determination processing unit 94 determines that the heat medium is insufficient, the supply processing unit 96 supplies the heat medium M1 to the tank 72 .

[0118] Specifically, the supply processing unit 96 drives the third pump 87 to supply the heat medium M1 stored in the heat medium storage unit 85 to the tank 72 .

[0119] For example, the supply processing unit 96 supplies the heat medium M1 to the container 72 until it is determined based on the first detected temperature that the heat medium shortage state has been resolved.

[0120] For example, when the amount of increase in the first detected temperature from the start of supplying the heat medium M1 to the container 72 exceeds the threshold, the determination processing unit 94 determines that the heat medium shortage state has been resolved. When the determination processing unit 94 determines that the heat medium shortage state has been resolved, the supply processing unit 96 stops supplying the heat medium M1 to the container 72.

[0121] In addition, when it is determined that the heat medium is insufficient, the control unit 7 may reduce the target temperature by a predetermined specific amount so that the duty ratio of the PWM signal is less than 100% until it is determined that the heat medium is insufficient. For example, the specific amount may be set according to the temperature inside the image forming apparatus 100B. In addition, the control unit 7 may obtain the time when the temperature of the heat medium M1 reaches the target temperature based on the first detected temperature when it is determined that the heat medium is insufficient, and notify the obtained time. Thus, the user can know the waiting time until the first detected temperature reaches the target temperature, that is, the waiting time until the image forming process is started.

[0122] Furthermore, the supply processing unit 96 may supply a predetermined amount of the heat medium M1 to the container 72 .

[0123] [Second motion control process] Below, refer to Fig. 9 An example of the procedure of the second motion control process executed by the control unit 7 in the image forming apparatus 100B and an example of the determination method of the present invention are described. The second motion control process is executed when the drive control unit 91 starts the drive control of the heater 73 .

[0124] <Step S21> First, in step S21, the control unit 7 performs a first determination process to determine whether the heat medium is insufficient based on the first detected temperature after the heater 73 starts to be driven. Here, the process of step S21 is an example of the determination step of the present invention and is executed by the determination processing unit 94 of the control unit 7.

[0125] Specifically, when the amount of increase in the first detected temperature from the start of driving of the heater 73 to the elapse of the reference time is equal to or less than the threshold value, the control unit 7 determines that the heat medium is insufficient.

[0126] <Step S22> In step S22, the control unit 7 switches the subsequent processing according to the result of the processing of step S21. Specifically, when it is determined by the processing of step S21 that the heat medium is insufficient (the "yes" side of S22), the control unit 7 transfers the processing to step S23. In addition, when it is determined by the processing of step S21 that the heat medium is not insufficient (the "no" side of S22), the control unit 7 ends the second action control processing.

[0127] <Step S23> In step S23, the control unit 7 executes a first notification process for notifying the insufficient state of the heat medium. In addition, the control unit 7 restricts execution of the image forming process. Here, the process of step S23 is executed by the first notification processing unit 95 of the control unit 7.

[0128] For example, the control unit 7 displays a message indicating the heat medium shortage state on the operation display unit 5. Thus, the user of the image forming apparatus 100B can know that the execution of the image forming process is restricted due to the heat medium shortage state.

[0129] Furthermore, even after determining that the heat medium is insufficient, the control unit 7 causes the drive control unit 91 to continue the drive control of the heater 73 .

[0130] <Step S24> In step S24, the control unit 7 executes a supply process of supplying the heat medium M1 to the container 72. Here, the process of step S24 is executed by the supply processing unit 96 of the control unit 7.

[0131] Specifically, the controller 7 supplies the heat medium M1 to the tank 72 until the heat medium shortage state is determined to be resolved based on the first detected temperature. This can reliably resolve the heat medium shortage state compared to a configuration in which a predetermined amount of heat medium M1 is supplied to the tank 72.

[0132] In addition, the control unit 7 may remove the restriction on execution of the image forming process when the heat medium shortage state is resolved.

[0133] Thus, in the image forming apparatus 100B, as shown in FIG. Figure 5 As shown, the first temperature sensor 75 is provided above the spiral portion 82 of the flexible tube 71 in the container 72. Thus, the first temperature sensor 75 can be used to determine whether the storage capacity of the heat medium M1 in the container 72 has decreased due to evaporation or leakage.

[0134] [Third Embodiment] Next, refer to Fig.10 The configuration of an image forming apparatus 100C according to a third embodiment of the present invention will be described.

[0135] The image forming apparatus 100C is different from the image forming apparatus 100B in the configurations of the control unit 7 and the heating device 63. The other configurations are common to the image forming apparatus 100B and the image forming apparatus 100C. Only the configurations of the image forming apparatus 100C that are different from the image forming apparatus 100B will be described below.

[0136] The heating device 63 of the image forming apparatus 100C further includes Fig.10 A liquid level sensor 78 is shown.

[0137] The liquid level sensor 78 detects the liquid level of the heat medium M1 in the container 72. For example, the liquid level sensor 78 is a so-called float sensor. The liquid level sensor 78 has a float portion that floats on the liquid surface of the heat medium M1 contained in the container 72, and uses the float portion to detect the liquid level of the heat medium M1. When the liquid level of the heat medium M1 contained in the container 72 is lower than the lower limit position P1 (refer to Figure 5 ), the liquid level sensor 78 outputs a third detection signal indicating this situation.

[0138] like Fig.10 As shown, the control unit 7 includes a drive control unit 91, a determination processing unit 94, a first notification processing unit 95, a supply processing unit 96, and a second notification processing unit 97. The device including the control unit 7 and the heating device 63 is another example of the heating device of the present invention.

[0139] Specifically, a third motion control program for causing the CPU 51 of the control unit 7 to function as the above-mentioned functional units is stored in advance in the ROM 52 of the control unit 7. The CPU 51 of the control unit 7 functions as the above-mentioned functional units by executing the third motion control program stored in the ROM 52.

[0140] The functions of the drive control section 91 and the first notification processing section 95 are the same as those of the drive control section 91 and the first notification processing section 95 included in the image forming apparatus 100B.

[0141] The determination processing unit 94 determines whether the amount of heat medium M1 stored in the container 72 is less than the lower limit amount based on the detection result of the liquid level sensor 78 and the first detected temperature after the heater 73 starts to be driven.

[0142] For example, when the amount of increase in the first detected temperature from the start of driving of the heater 73 to the elapse of the reference time is equal to or less than the threshold value, the determination processing unit 94 determines that the heat medium is insufficient.

[0143] Furthermore, when the third detection signal is output from the liquid level sensor 78 , the determination processing unit 94 determines that the heat medium is insufficient.

[0144] If the heat medium shortage state is determined not to exist based on the detection result of the liquid level sensor 78 and the first detected temperature after the heater 73 starts to be driven, the determination processing unit 94 determines that the heat medium shortage state is not to exist.

[0145] Here, when the determination result based on the detection result of the liquid level sensor 78 is different from the determination result based on the first detected temperature after the start of driving of the heater 73, the determination processing unit 94 determines that the liquid level sensor 78 or the first temperature sensor 75 has failed. Specifically, the determination processing unit 94 determines that the sensor of the liquid level sensor 78 and the first temperature sensor 75 that is not in the insufficient heat medium state according to the detection result has failed.

[0146] Alternatively, the determination processing unit 94 may determine whether or not the heat medium is insufficient based only on the detection result of the liquid level sensor 78 .

[0147] When the determination processing unit 94 determines that the heat medium is insufficient, the supply processing unit 96 supplies the heat medium M1 to the tank 72 .

[0148] Specifically, the supply processing unit 96 drives the third pump 87 to supply the heat medium M1 stored in the heat medium storage unit 85 to the tank 72 .

[0149] For example, the supply processing unit 96 supplies the heat medium M1 to the container 72 until it is determined based on the detection result of the liquid level sensor 78 that the heat medium shortage state is resolved.

[0150] For example, when the third detection signal is no longer output from the liquid level sensor 78 , the determination processing unit 94 determines that the insufficient heat medium state is resolved. When the determination processing unit 94 determines that the insufficient heat medium state is resolved, the supply processing unit 96 stops supplying the heat medium M1 to the container 72 .

[0151] When the determination processing unit 94 determines that the liquid level sensor 78 or the first temperature sensor 75 has failed, the second notification processing unit 97 notifies the user of the failure.

[0152] For example, the second notification processing unit 97 causes the operation display unit 5 to display a message indicating that a failure has occurred in the liquid level sensor 78 or the first temperature sensor 75 .

[0153] [Third motion control process] Below, refer to Fig.11 An example of the procedure of the third operation control process executed by the control unit 7 in the image forming apparatus 100C and another example of the determination method of the present invention are described. The third operation control process is executed when the drive control unit 91 starts the drive control of the heater 73 .

[0154] <Step S31> First, in step S31, the control unit 7 executes a second determination process, which determines whether the storage capacity of the heat medium M1 in the container 72 is less than the lower limit amount, based on the detection result of the liquid level sensor 78 and the first detected temperature after the start of driving the heater 73. Here, the process of step S31 is another example of the determination step of the present invention, and is executed by the determination processing unit 94 of the control unit 7.

[0155] Specifically, when the amount of increase in the first detected temperature from the start of driving the heater 73 to the lapse of the reference time is less than or equal to the threshold value, the control unit 7 determines that the heat medium is insufficient. In addition, when the third detection signal is output from the liquid level sensor 78, the control unit 7 determines that the heat medium is insufficient. In addition, when it is determined that the heat medium is not insufficient based on the detection result of the liquid level sensor 78 and it is determined that the heat medium is not insufficient based on the first detected temperature after the start of driving the heater 73, the control unit 7 determines that the heat medium is not insufficient.

[0156] <Step S32> In step S32, the control unit 7 switches the subsequent processing according to the result of the processing of step S31. Specifically, when it is determined by the processing of step S31 that the heat medium is insufficient (the "yes" side of S32), the control unit 7 transfers the processing to step S33. In addition, when it is determined by the processing of step S31 that the heat medium is not insufficient (the "no" side of S32), the control unit 7 ends the third action control processing.

[0157] <Step S33> In step S33, the control unit 7 executes the first notification process of notifying the insufficient state of the heat medium. In addition, the control unit 7 restricts the execution of the image forming process. Here, the process of step S33 is executed by the first notification processing unit 95 of the control unit 7.

[0158] <Step S34> In step S34, the control unit 7 executes the supply process of supplying the heat medium M1 to the container 72. Here, the process of step S34 is executed by the supply processing unit 96 of the control unit 7.

[0159] Specifically, the control unit 7 supplies the heat medium M1 to the tank 72 until it is determined based on the detection result of the liquid level sensor 78 that the heat medium shortage state is resolved.

[0160] In addition, the control unit 7 may remove the restriction on execution of the image forming process when the heat medium shortage state is resolved.

[0161] <Step S35> In step S35, the control unit 7 switches the subsequent processing according to the result of the processing in step S31. Specifically, in the case where the determination result based on the detection result of the liquid level sensor 78 is different from the determination result based on the first detection temperature after the start of the drive of the heater 73 in the processing in step S31 (the "yes" side of S35), the control unit 7 transfers the processing to step S36. In addition, in the case where the determination result based on the detection result of the liquid level sensor 78 is the same as the determination result based on the first detection temperature after the start of the drive of the heater 73 in the processing in step S31 (the "no" side of S35), the control unit 7 ends the third action control processing.

[0162] <Step S36> In step S36, the control unit 7 notifies that a failure has occurred in the liquid level sensor 78 or the first temperature sensor 75. Here, the process of step S36 is executed by the second notification processing unit 97 of the control unit 7.

[0163] Specifically, when it is determined in the process of step S31 that the heat medium is not insufficient based on the detection result of the liquid level sensor 78, the control unit 7 displays a message indicating that the liquid level sensor 78 is faulty on the operation display unit 5. In addition, when it is determined in the process of step S31 that the heat medium is not insufficient based on the first detected temperature after the start of driving the heater 73, the control unit 7 displays a message indicating that the first temperature sensor 75 is faulty on the operation display unit 5. Thus, the user of the image forming apparatus 100C can take measures such as replacing the faulty sensor.

[0164] As described above, the image forming apparatus 100C is provided with the liquid level sensor 78 for detecting the liquid level of the heat medium M1 in the container 72. This makes it possible to determine whether the storage capacity of the heat medium M1 in the container 72 has decreased due to evaporation or leakage.

[0165] [Additional Notes on the Invention] The following is a summary of the invention extracted from the above-mentioned embodiment. In addition, each structure and each processing function described in the following supplementary notes can be selected and combined arbitrarily.

[0166] <Additional Note 1> A heating device comprises: a coil having a spiral portion formed in a spiral shape; a receiving portion receiving the spiral portion and a heat medium for heating a liquid in the spiral portion; a heater for heating the receiving portion; a liquid level sensor for detecting the liquid level of the heat medium in the receiving portion; and a determination processing portion for determining, based on a detection result of the liquid level sensor, whether a heat medium shortage state is reached in which the storage capacity of the heat medium in the receiving portion is lower than a predetermined lower limit.

[0167] <Note 2> The heating device according to Supplementary Note 1 further comprises a first notification processing unit, and when the determination processing unit determines that the heat medium is in a shortage state, the first notification processing unit notifies the state.

[0168] <Addendum 3> The heating device according to Supplementary Note 1 or 2, further comprising a supply processing unit configured to supply the heat medium to the storage unit when the determination processing unit determines that the heat medium is in a shortage state.

[0169] <Addendum 4> According to the heating device according to Supplementary Note 3, the supply processing unit supplies the heat medium to the storage unit until it is determined that the heat medium shortage state is resolved.

[0170] <Addendum 5> The heating device according to any one of Appendixes 1 to 4 comprises: a contact temperature sensor, which is arranged in the housing portion at an upper side than the spiral portion, and is used to detect the temperature of the heat medium; and a drive control portion, which controls the drive of the heater according to the detected temperature detected by the temperature sensor, and the determination processing portion determines whether the heat medium is insufficient based on the detection result of the liquid level sensor and the detected temperature after the start of the drive of the heater.

[0171] <Addendum 6> According to the heating device described in Note 5, when the judgment result based on the detection result of the liquid level sensor is different from the judgment result based on the detected temperature after the driving of the heater is started, the judgment processing unit judges that the liquid level sensor or the temperature sensor is faulty, and the heating device has a second notification processing unit. When the judgment processing unit judges that the liquid level sensor or the temperature sensor is faulty, the second notification processing unit notifies the situation.

[0172] <Addendum 7> An image forming apparatus comprises the heating device according to any one of Supplementary Notes 1 to 6, and forms an image using ink heated by the heating device.

[0173] <Addendum 8> A determination method is performed by a heating device, the heating device comprising: a coil having a spiral portion formed in a spiral shape; a receiving portion for receiving the spiral portion and a heat medium for heating a liquid in the spiral portion; a heater for heating the receiving portion; and a liquid level sensor for detecting a liquid level of the heat medium in the receiving portion, the determination method comprising a determination step for determining, based on a detection result of the liquid level sensor, whether a heat medium shortage state is reached in which a storage capacity of the heat medium in the receiving portion is lower than a predetermined lower limit.

[0174] The scope of the present invention is not limited to the above content, but is defined by the description of the claims, so it can be considered that the embodiments described in this specification are only illustrative, not limiting. Therefore, all changes that do not depart from the scope and limits of the claims, as well as contents that are equivalent to the scope and limits of the claims, are included in the scope of the claims.

Claims

1. A heating device, characterized in that: have: The snake tube has a spiral portion formed in a spiral shape; a receiving portion for receiving the spiral portion and a heat medium of a liquid used for heating the spiral portion; A heater for heating the receiving portion; a liquid level sensor for detecting a liquid level of the heat medium in the receiving portion; as well as The determination processing unit determines whether the amount of the heat medium stored in the storage unit is less than a predetermined lower limit amount based on the detection result of the liquid level sensor.

2. The heating device according to claim 1, characterized in that: A first notification processing unit is provided, and when the determination processing unit determines that the heat medium is in a shortage state, the first notification processing unit notifies the state.

3. The heating device according to claim 1, characterized in that: A supply processing unit is provided, and when the determination processing unit determines that the heat medium is in a shortage state, the supply processing unit supplies the heat medium to the storage unit.

4. The heating device according to claim 3, characterized in that: The supply processing unit supplies the heat medium to the storage unit until it is determined that the heat medium shortage state is resolved.

5. The heating device according to claim 1, characterized in that: have: a contact-type temperature sensor, disposed in the housing portion above the spiral portion, for detecting the temperature of the heat medium; and a drive control unit that controls the drive of the heater according to the detected temperature detected by the temperature sensor, The determination processing unit determines whether the heat medium is insufficient based on the detection result of the liquid level sensor and the detected temperature after the start of driving of the heater.

6. The heating device according to claim 5, characterized in that: When a determination result based on a detection result of the liquid level sensor is different from a determination result based on the detected temperature after the start of driving of the heater, the determination processing unit determines that the liquid level sensor or the temperature sensor has failed, The heating device includes a second notification processing unit, and when the determination processing unit determines that the liquid level sensor or the temperature sensor has failed, the second notification processing unit notifies the failure.

7. An image forming device, characterized in that: A heating device according to any one of claims 1 to 6, An image is formed using the ink heated by the heating device.

8. A determination method, characterized in that: The heating device comprises: a coil having a spiral portion formed in a spiral shape; a receiving portion receiving the spiral portion and a heat medium for heating a liquid in the spiral portion; a heater for heating the receiving portion; and a liquid level sensor for detecting a liquid level of the heat medium in the receiving portion. The determination method includes a determination step of determining whether a heat medium shortage state in which the storage volume of the heat medium in the storage section is less than a predetermined lower limit is reached based on a detection result of the liquid level sensor.

Images