Heating device, image formation device, and determination method

Abstract

To provide a heating device capable of determining lowering of a heating function, an image formation device, and a determination method.SOLUTION: A heating device 63 includes: a corrugated tube 71 having a spiral part 82 formed in a spiral shape; a container 72 for storing the spiral part 82 and a liquid heat medium M1; a heater 73 for heating the container 72; a contact type first temperature sensor 75 provided above the spiral part 82 in the container 72, and used for detecting a temperature of the heat medium M1; a drive control part for controlling drive of the heater 73, on the basis of a detection temperature detected by the first temperature sensor 75; and a determination processing part for determining whether or not a capacity of the heat medium M1 in the container 72 is in a heat medium shortage state lower than a lower limit value, on the basis of the detection temperature after start of the drive of the heater 73.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a warming device, an image forming apparatus, and a determination method. [Background technology]

[0002] Inkjet image forming apparatuses are 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 (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2022-18871 Summary of the Invention [Problem to be solved by the invention]

[0004] By using a heat medium such as water instead of the metal plate, it is possible to suppress a sudden increase in the temperature of the ink in the warming device. For example, a configuration including a coiled tube disposed in a container filled with the heat medium and a heater for heating the container can be considered.

[0005] In the above-described configuration, the amount of the heat medium contained in the container may decrease due to evaporation or leakage. When the amount of the heat medium contained in the container decreases, the ink heating function of the heater decreases.

[0006] An object of the present invention is to provide a heating device, an image forming apparatus, and a method for determining whether a heating function has deteriorated. [Means for solving the problem]

[0007] A heating device according to one aspect of the present invention includes a coiled tube, a storage unit, a heater, a temperature sensor, a drive control unit, and a judgment processing unit. The coiled tube has a helical portion formed in a helical shape. The storage unit stores the helical portion and a liquid heat medium used to heat the helical portion. The heater heats the storage unit. The temperature sensor is of a contact type, is provided above the helical portion in the storage unit, and is used to detect the temperature of the heat medium. The drive control unit controls the driving of the heater based on a detected temperature detected by the temperature sensor. The judgment processing unit judges whether or not the amount of the heat medium stored in the storage unit is below a predetermined lower limit amount based on the detected temperature after the heater starts to be driven, resulting in a heat medium shortage state.

[0008] An image forming apparatus according to another aspect of the present invention includes the above-described heating device, and forms an image using ink heated by the heating device.

[0009] A method for determining the temperature of the heat medium in the container is performed by a heating device including a coiled tube having a helical portion formed in a helical shape, a container for containing the helical portion and a liquid heat medium used to heat the helical portion, a heater for heating the container, a contact-type temperature sensor provided in the container above the helical portion and used to detect the temperature of the heat medium, and a drive control unit for controlling the drive of the heater based on the detected temperature detected by the temperature sensor, and includes a determination step. In the determination step, it is determined based on the detected temperature after the heater starts to be driven that the amount of the heat medium in the container is below a predetermined lower limit amount, and thus the heat medium is insufficient. Effect of the Invention

[0010] According to the present invention, it is possible to determine a decrease in the heating function. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing the configuration of an image forming apparatus according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing the configuration of an image forming section and a transport unit of the image forming apparatus according to the first embodiment of the present invention. [Diagram 3] FIG. 3 is a block diagram showing a system configuration of the image forming apparatus according to the first embodiment of the present invention. [Figure 4] FIG. 4 is a diagram showing the configuration of an ink supply unit of the image forming apparatus according to the first embodiment of the present invention. [Diagram 5] FIG. 5 is a diagram showing the configuration of a warming device of the image forming apparatus according to the first embodiment of the present invention. [Figure 6] FIG. 6 is a flowchart showing an example of a first operation control process executed in the image forming apparatus according to the first embodiment of the present invention. [Figure 7] FIG. 7 is a block diagram showing a system configuration of an image forming apparatus according to the second embodiment of the present invention. [Figure 8] FIG. 8 is a diagram showing a configuration of an ink supply unit of an image forming apparatus according to the second embodiment of the present invention. [Figure 9] FIG. 9 is a flowchart showing an example of a second operation control process executed in the image forming apparatus according to the second embodiment of the present invention. [Figure 10] FIG. 10 is a block diagram showing a system configuration of an image forming apparatus according to the third embodiment of the present invention. [Figure 11] FIG. 11 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 OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Note that the following embodiment is an example of the present invention, and is not intended to limit the technical scope of the present invention.

[0013] [First embodiment] First, the configuration of an image forming apparatus 100A according to a first embodiment of the present invention will be described with reference to Fig. 1 to Fig. 3. Fig. 1 is a cross-sectional view showing the configuration of the image forming apparatus 100A. Fig. 2 is a plan view showing the configurations of an image forming section 3 and a transport unit 4. In Fig. 1, a sheet transport path R11 is indicated by a two-dot chain line.

[0014] Image forming apparatus 100A is a printer capable of forming an image on a sheet by an inkjet method. Note that the present invention may be applied to image forming apparatuses such as fax machines, copy machines, and multifunction machines capable of forming an image on a sheet by an inkjet method.

[0015] As shown in FIGS. 1 and 3, the image forming apparatus 100A includes a housing 1, a sheet conveying section 2, an image forming section 3, a conveying unit 4, an operation display section 5, a storage section 6, a control section 7, and an ink supply section 8.

[0016] The housing 1 houses each of the components of the image forming apparatus 100A. A paper feed cassette 11 is removably provided in the housing 1. The paper feed cassette 11 houses sheets on which images are formed. A paper output tray 12 is provided on the outer surface of the housing 1. Sheets on which images are formed by the image forming unit 3 are output to the paper output tray 12. Inside the housing 1, the sheets housed in the paper feed cassette 11 are transported along a sheet transport path R11 (see FIG. 1) that passes through an image formation position by the image forming unit 3 and reaches the paper output tray 12.

[0017] The sheet transport unit 2 transports the sheets stored in the paper feed cassette 11 along a sheet transport path R11 (see FIG. 1). As shown in FIG. 1, the sheet transport unit 2 includes a pickup roller 21 and a plurality of transport rollers 22. The pickup roller 21 picks up the top sheet of the sheet stack stored in the paper feed cassette 11 and sends the sheet to the sheet transport path R11. The plurality of transport rollers 22 are arranged side by side along the sheet transport path R11. Each of the transport rollers 22 transports the sheet along the sheet transport path R11. Each of the transport rollers 22 transports the sheet in a transport direction D11 (see FIG. 1) from the paper feed cassette 11 to the paper discharge tray 12.

[0018] The image forming unit 3 forms an image based on image data on a sheet supplied from the sheet conveying unit 2. As shown in FIG.

[0019] 2, each of the line heads 31 to 34 is elongated in a width direction D12 perpendicular to the transport direction D11. Specifically, each of the line heads 31 to 34 has a length in the width direction D12 corresponding to the width of the largest sheet among the sheets that can be accommodated in the paper feed cassette 11. The line heads 31 to 34 are arranged side by side at equal intervals along the transport direction D11.

[0020] As shown in FIG. 2, each of the line heads 31 to 34 has a plurality of recording heads 30. The recording heads 30 eject ink toward a sheet transported by the transport unit 4. Specifically, a large number of nozzles 36 (see FIG. 2) used for ejecting the ink are provided on the surface of the recording heads 30 facing the sheet. Each of the recording heads 30 provided in the line head 31 ejects the black ink. Each of the recording heads 30 provided in the line head 32 ejects the cyan ink. Each of the recording heads 30 provided in the line head 33 ejects the magenta ink. Each of the recording heads 30 provided in the line head 34 ejects the yellow ink.

[0021] In this embodiment, the line head 31 has three recording heads 30 arranged in a staggered manner along the width direction D12. Similarly to the line head 31, each of the other line heads 32 to 34 also has three recording heads 30 arranged in a staggered manner along the width direction D12. Note that Fig. 2 shows the image forming unit 3 as viewed from above in Fig. 1.

[0022] 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. Furthermore, the number of recording heads 30 provided in each of the line heads 31 to 34 does not need to be limited to three.

[0023] As shown in FIG. 1, the transport unit 4 is disposed below the line heads 31 to 34. The transport unit 4 transports the sheet while facing the recording head 30. For example, the transport unit 4 transports the sheet by a predetermined transport amount every time the recording head 30 ejects the ink. The transport unit 4 stops transporting the sheet while the recording head 30 ejects the ink. As shown in FIG. 1, the transport unit 4 includes a transport belt 41 on which the sheet is placed, a first tension roller 42, a second tension roller 43, and a third tension roller 44 that stretch the transport belt 41, and a transport frame 45 that supports them. The gap between the transport 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 is a predetermined distance (for example, 1 mm).

[0024] The first tension roller 42 is rotationally driven by a rotational driving force supplied from a motor (not shown). As a result, the conveyor belt 41 rotates in a direction capable of conveying the sheet in the conveying direction D11 (see FIG. 1). The conveyor unit 4 is also provided with a suction unit (not shown) that sucks air through a number of through holes formed in the conveyor belt 41 in order to attract the sheet to the conveyor belt 41. A pressure roller 46 is provided above the first tension roller 42 to press the sheet against the conveyor belt 41 for conveyance.

[0025] 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 in response 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 in response to user operations. For example, the operation unit is a touch panel. The operation display unit 5 is provided on the top surface of the housing 1.

[0026] The storage unit 6 is a non-volatile storage device. For example, the storage unit 6 is a non-volatile memory such as a flash memory. The storage unit 6 may be a solid state drive (SSD) or a hard disk drive (HDD).

[0027] The control unit 7 performs overall control of the image forming apparatus 100A. As shown in FIG. 3, 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 processing. The ROM 52 is a non-volatile storage device in which information such as a control program for causing the CPU 51 to perform various processing is stored in advance. The RAM 53 is a volatile or non-volatile storage device used as a temporary storage memory (work area) for various processing performed by the CPU 51. The CPU 51 performs overall control of the image forming apparatus 100A by executing various control programs stored in advance in the ROM 52. The control unit 7 may be a control unit provided separately from a main control unit that performs overall control of the image forming apparatus 100A. The control unit 7 may also be configured with an electronic circuit such as an integrated circuit (ASIC).

[0028] [Configuration of ink supply unit 8] Next, the configuration of the ink supply unit 8 will be described with reference to Fig. 4. In Fig. 4, the first supply path 62 and the second supply path 66 are indicated by thick lines.

[0029] The ink supply unit 8 supplies the ink to the recording head 30. An ink supply unit 8 is provided for each recording head 30. The ink supply units 8 corresponding to the line heads 31 to 34 have the same configuration, except that the colors of the inks supplied are different.

[0030] As shown in FIG. 4, the ink supply unit 8 includes an ink container 61 , a first supply path 62 , a heating device 63 , a first pump 64 , a sub-ink tank 65 , a second supply path 66 , and a second pump 67 .

[0031] The ink container 61 contains the ink. For example, the ink is an aqueous ink whose main solvent is water. However, the ink may be a non-aqueous ink whose main solvent is an organic solvent.

[0032] The first supply path 62 is an ink flow path provided between the ink container 61 and the sub-ink tank 65. The first supply path 62 is made of a flexible material. For example, the first supply path 62 is a resin tube.

[0033] The heating device 63 is provided in the first supply path 62. The heating device 63 heats the ink flowing through the first supply path 62. The image forming apparatus 100A forms an image using the ink heated by the heating device 63.

[0034] The first pump 64 is provided in the first supply path 62. The first pump 64 causes the ink in the first supply path 62 to flow in a flow direction D21 (see FIG. 4) toward the recording head 30.

[0035] The sub-ink tank 65 contains the ink supplied from the ink container 61. The ink contained in the sub-ink tank 65 is supplied to the recording head 30.

[0036] The second supply path 66 is an ink flow path provided between the sub-ink tank 65 and the recording head 30. The second supply path 66 is made of a flexible material. For example, the second supply path 66 is a resin tube.

[0037] The second pump 67 is provided in the second supply path 66. The second pump 67 causes the ink in the second supply path 66 to flow in a flow direction D21 (see FIG. 4).

[0038] The image forming apparatus 100A does not necessarily have to include the sub-ink tank 65. In other words, the recording head 30 may receive the ink directly from the ink container 61.

[0039] [Configuration of Heating Device 63] Next, the configuration of the warming device 63 will be described with reference to Fig. 5. Here, Fig. 5 is a cross-sectional view showing the configuration of the warming device 63.

[0040] As shown in FIG. 5, the warming device 63 includes a coiled tube 71, a container 72, a heater 73, a thermal insulator 74, a first temperature sensor 75, and a second temperature sensor .

[0041] The coiled tube 71 is a tube formed in a spiral shape. The coiled tube 71 is disposed in a position in which the spiral axis is aligned along the vertical direction. For example, the coiled tube 71 is formed by processing a straight metal tube into a spiral shape. For example, the straight tube has a cross-sectional shape of a perfect circle and is made of stainless steel. Note that the straight tube may have a cross-sectional shape of an ellipse or the like.

[0042] As shown in FIG. 5, the serpentine tube 71 includes a first piping portion 81, a spiral portion 82, and a second piping portion 83. The first piping portion 81 extends along the vertical direction. An upper end of the first piping portion 81 is connected to the ink container 61 (see FIG. 4) via the first supply path 62. The spiral portion 82 is formed in a spiral shape extending upward from the lower end of the first piping portion 81. The second piping portion 83 extends vertically upward from an upper end 84 (see FIG. 5) of the spiral portion 82. An upper end of the second piping portion 83 is connected to the first pump 64 (see FIG. 4) via the first supply path 62.

[0043] The container 72 contains the spiral portion 82 of the coiled tube 71 and a liquid heat transfer medium M1 (see FIG. 5) used to heat the spiral portion 82. The container 72 is an example of a container of the present invention.

[0044] For example, container 72 includes a cylindrical portion extending along the vertical direction, a disk-shaped bottom portion closing the lower end of the cylindrical portion, and a disk-shaped top plate portion closing the upper end of the cylindrical portion. First piping portion 81 and second piping portion 83 of corrugated tube 71 each extend from inside container 72 to outside container 72 through holes formed in the top plate portion. Note that container 72 does not necessarily have to include the top plate portion. Also, container 72 is not limited to a cylindrical shape, and may be formed in a hollow prismatic shape.

[0045] The inside of the container 72 is filled with a quantity of heat medium M1 (see FIG. 5) such that the spiral portion 82 is submerged. That is, inside the container 72, the water surface of the heat medium M1 is located above the upper end 84 (see FIG. 5) of the spiral portion 82. For example, the heat medium M1 is water. Note that the heat medium M1 is not limited to water, and may be a fluid such as oil.

[0046] 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 that covers the heating wire. The heater 73 is provided so as to cover the outer surface of the container 72. The heater 73 may be a silicon rubber heater or the like.

[0047] In the heating device 63, the heater 73 heats the container 72, thereby heating the heat medium M1 contained in the container 72. This heats the ink flowing inside the spiral portion 82 disposed in the heat medium M1. In comparison with a configuration in which the heat of the heater 73 is transferred to the ink via a metal plate that is in contact with both the heater 73 and the pipe through which the ink flows, the heating device 63 is able to suppress a sudden rise in the temperature of the ink.

[0048] Incidentally, the heat medium M1 in the container 72 heats up faster the closer it is to the heater 73. That is, in the heating device 63, the temperature of the heat medium M1 becomes non-uniform for a while after the heater 73 starts to be driven. If the temperature of the heat medium M1 is non-uniform, the temperature of the ink after being heated by the heating device 63 becomes unstable.

[0049] In contrast, in the warming device 63 according to the first embodiment of the present invention, as will be described below, it is possible to shorten the time until the temperature of the heat medium M1 is uniformed.

[0050] Specifically, the heater 73 heats the container 72 below the upper end 84 of the spiral portion 82 , but does not heat the container 72 above the upper end 84 .

[0051] That is, in the heating device 63, the upper part of the heat medium M1 contained in the container 72, including the water surface, is not heated by the heater 73. As a result, a temperature difference occurs between the upper part and the bottom part of the heat medium M1 contained in the container 72, and convection occurs within the heat medium M1. Therefore, it is possible to shorten the time until the temperature of the heat medium M1 is uniformed. Also, it is possible to shorten the time until the temperature of the heat medium M1 is uniformed without providing a configuration for stirring the heat medium M1.

[0052] For example, the heater 73 heats at least the bottom of the container 72 .

[0053] For example, the heater 73 heats an area AR1 (see FIG. 5) of the cylindrical portion of the container 72, the area AR1 extending from the lower end to a portion below the upper end 84 of the spiral portion 82. For example, the planar heater 73 is wrapped around the area AR1.

[0054] The heater 73 may heat a part of the cylindrical portion and the bottom surface of the bottom of the container 72. The heater 73 may also heat only the bottom surface of the bottom of the container 72. The heater 73 may also heat only a part of the upper side of the region AR1. In other words, the heater 73 does not have to heat the bottom of the container 72.

[0055] 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.

[0056] The first temperature sensor 75 is a contact-type temperature sensor provided in the container 72 and used to detect the temperature of the heat medium M1. For example, as shown in FIG. 5, the first temperature sensor 75 is provided at a position above the spiral portion 82 of the coiled tube 71. In this case, the inside of the container 72 is filled with the heat medium M1 in an amount that submerges the first temperature sensor 75. For example, the first temperature sensor 75 is disposed inside the spiral portion 82. The first temperature sensor 75 outputs a first detection signal including a signal value according to the temperature of the heat medium M1 that it contacts. The first detection signal output from the first temperature sensor 75 is input to the control unit 7. The first temperature sensor 75 may be disposed outside the spiral portion 82. The first temperature sensor 75 may also be disposed below the upper end 84 of the spiral portion 82.

[0057] The second temperature sensor 76 is provided outside the container 72 and is used to detect the temperature of the container 72. For example, as shown in FIG. 5, the second temperature sensor 76 is provided between the heater 73 and the insulating material 74. The second temperature sensor 76 outputs a second detection signal including a signal value according 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. The second temperature sensor 76 may be provided in contact with the outer surface of the container 72.

[0058] [Configuration of control unit 7] Next, the configuration of the control unit 7 will be described in more detail with reference to FIG.

[0059] 3, the control unit 7 includes a drive control unit 91, a stop processing unit 92, and an acquisition processing unit 93. An apparatus including the control unit 7 and the warming device 63 is an example of the warming device of the present invention.

[0060] Specifically, a first operation control program for causing the CPU 51 to function as each of the above-mentioned functional units is stored in advance in the ROM 52 of the control unit 7. The CPU 51 executes the first operation control program stored in the ROM 52 to function as each of the above-mentioned functional units.

[0061] The first operation control program may be recorded on a computer-readable recording medium such as a CD, a DVD, or a flash memory, and may be read from the recording medium and stored in a storage device such as the memory unit 6. Some or all of the above-mentioned functional units may be configured with electronic circuits such as application specific integrated circuits (ASICs). The first operation control program may be a program for causing a plurality of processors to function as the functional units included in the control unit 7.

[0062] 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 .

[0063] 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 based on the temperature of the ink suitable for printing. For example, the drive control unit 91 controls the driving of the heater 73 by PID control. For example, in the image forming apparatus 100A, a switching element (not shown) capable of switching the conduction and interruption of the power supply path is provided on a power supply path between a power source (not shown) and the heater 73. The drive control unit 91 inputs a PWM signal having a duty ratio according to the difference between the first detected temperature and the target temperature to the switching element to control the on / off of the switching element. As a result, the amount of power supply to the heater 73 is adjusted according to the difference between the first detected temperature and the target temperature.

[0064] For example, when an image forming process is executed to form an image based on image data using the image forming unit 3, the drive control unit 91 executes 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 to supply the ink, and the image forming process is started.

[0065] In the heating device 63, the first temperature sensor 75 is disposed in the heat medium M1 where convection occurs. That is, the first temperature sensor 75 is subjected to the flow of the heat medium M1. Therefore, in the heating device 63, an abnormality such as a breakdown or poor contact may occur in the first temperature sensor 75. If the abnormality occurs in the first temperature sensor 75, the drive control of the heater 73 may not function, and the temperature of the heat medium M1 may rise excessively.

[0066] In contrast, in the warming device 63 according to the first embodiment of the present invention, as will be described below, it is possible to prevent the temperature of the heat medium M1 from increasing excessively.

[0067] The stop processing unit 92 stops the driving of the heater 73 when the temperature of the container 72 exceeds a predetermined upper limit temperature. The stop processing unit 92 is an example of the stop unit of the present invention.

[0068] Specifically, the stop processing unit 92 stops driving the heater 73 when the second detected temperature detected by the second temperature sensor 76 exceeds the upper limit temperature. The upper limit temperature is a temperature higher than the target temperature.

[0069] Furthermore, the stop processing unit 92 limits the execution of the image forming process.

[0070] Here, the warming device 63 includes a thermostat 77 as shown in FIG.

[0071] When the temperature of the container 72 exceeds a predetermined cut-off temperature, the thermostat 77 cuts off the power supply path of the heater 73 to stop the operation of the heater 73. For example, the thermostat 77 is provided on the outer surface of the container 72. For example, as shown in FIG. 5, the thermostat 77 is disposed 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 stopping portion of the present invention. The cut-off temperature is another example of the upper limit temperature of the present invention. It should be noted that a temperature fuse may be used instead of the thermostat 77.

[0072] The acquisition processing unit 93 acquires the amount of the heat medium M1 contained in the container 72 based on the rate of increase in the second detected temperature from when the heater 73 starts to be driven.

[0073] For example, in image forming apparatus 100A, table data in which the rate of rise of the second detected temperature corresponds to the capacity of heat medium M1 is stored in advance in storage unit 6. In the table data, a correspondence relationship between the rate of rise of the second detected temperature and the capacity of heat medium M1 is determined such that the faster the rate of rise of the second detected temperature is, the smaller the capacity of heat medium M1 is. Note that the table data can be created based on the results of an experiment in which the rate of rise of the second detected temperature corresponding to each of a plurality of capacity of heat medium M1 is measured.

[0074] 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 until a predetermined specific time has elapsed. Then, the acquisition processing unit 93 acquires, in the table data, the capacity of the heat medium M1 associated with the acquired rate of increase of the second detected temperature as the current capacity of the heat medium M1 in the container 72.

[0075] For example, when the acquisition processing unit 93 acquires the amount of the heat medium M1 stored in the container 72, the control unit 7 notifies the amount. For example, the control unit 7 causes the operation display unit 5 to display the amount of the heat medium M1 stored in the container 72 acquired by the acquisition processing unit 93.

[0076] If the amount of heat medium M1 contained in the container 72 acquired by the acquisition processing unit 93 is less than a predetermined lower limit amount, the control unit 7 may stop driving the heater 73 and notify the fact that the heat medium is insufficient. The heat medium insufficient state is a state in which the amount of heat medium M1 contained in the container 72 is below the lower limit amount. The lower limit amount is the amount of heat medium M1 contained in the container 72 when the water level of the heat medium M1 is at the lower limit position P1 shown in FIG. 5. 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. In FIG. 5, the lower limit position P1 is indicated by a dashed line.

[0077] Furthermore, the control unit 7 may notify the amount of the heat medium M1 contained in the container 72 only when the amount of the heat medium M1 contained in the container 72 acquired by the acquisition processing unit 93 is less than a predetermined amount that is greater than the lower limit amount.

[0078] [First operation control process] An example of the procedure of the first operation control process executed by the control unit 7 in the image forming apparatus 100A will be described below with reference to Fig. 6. Here, steps S11, S12, etc. indicate the numbers of the processing procedures (steps) executed by the control unit 7. The first operation control process is executed when the drive control unit 91 starts drive control of the heater 73.

[0079] <Step S11> First, in step S11, the control unit 7 acquires the amount of the heat medium M1 contained in the container 72 based on the rate of increase of the second detected temperature from the start of driving of the heater 73. Here, the process of step S11 is executed by the acquisition processing unit 93 of the control unit 7.

[0080] Specifically, the control unit 7 acquires the rate of increase of the second detected temperature based on the amount of increase of the second detected temperature from when the heater 73 starts to be driven until the specific time has elapsed. Then, the control unit 7 acquires, in the table data, the capacity of the heat medium M1 associated with the acquired rate of increase of the second detected temperature as the current capacity of the heat medium M1 in the container 72.

[0081] <Step S12> In step S12, the control unit 7 notifies the amount of the heat medium M1 contained in the container 72 acquired by the process of step S11.

[0082] Specifically, the control unit 7 causes the amount of heat medium M1 contained in the container 72 acquired by the process of step S11 to be displayed on the operation display unit 5. This allows the user of the image forming apparatus 100A to determine whether or not it is necessary to replenish the heat medium M1.

[0083] <Step S13> In step S13, the control unit 7 determines whether the first detected temperature detected by the first temperature sensor 75 has reached the target temperature.

[0084] Here, when the control unit 7 determines that the first detected temperature has reached the target temperature (Yes in S13), it ends the first operation control process. On the other hand, when the first detected temperature has not reached the target temperature (No in S13), the control unit 7 shifts the process to step S14.

[0085] <Step S14> In step S14, the control unit 7 determines whether or not the second detected temperature detected by the second temperature sensor 76 exceeds the upper limit temperature.

[0086] Here, when the control unit 7 determines that the second detected temperature exceeds the upper limit temperature (Yes side of S14), the control unit 7 shifts the process to step S15. On the other hand, when the second detected temperature does not exceed the upper limit temperature (No side of S14), the control unit 7 shifts the process to step S13.

[0087] <Step S15> In step S15, the control unit 7 stops driving the heater 73. The control unit 7 also limits the 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.

[0088] <Step S16> In step S16, the control unit 7 notifies the user that the driving of the heater 73 has been stopped due to the occurrence of the abnormality or the shortage of the heat medium, thereby enabling the user of the image forming apparatus 100A to take action such as eliminating the abnormality or refilling the heat medium M1.

[0089] In this way, in the image forming apparatus 100A, the area below the upper end 84 of the spiral portion 82 in the container 72 is heated, and the area above the upper end 84 is not heated. This causes a temperature difference between the upper and bottom parts of the heat medium M1 contained in the container 72, and convection occurs within the heat medium M1. This makes it possible to shorten the time it takes for the temperature of the heat medium M1 to become uniform.

[0090] Incidentally, in the image forming apparatus 100A, the amount of heat medium M1 contained in the container 72 may decrease due to evaporation or leakage. When the amount of heat medium M1 contained in the container 72 decreases, the ink heating function of the heater 63 decreases.

[0091] In contrast, in the image forming apparatus 100B according to the second embodiment of the present invention, it is possible to determine the deterioration of the heating function, as will be described below.

[0092] [Second embodiment] Next, a configuration of an image forming apparatus 100B according to a second embodiment of the present invention will be described with reference to FIGS.

[0093] Image forming apparatus 100B differs from image forming apparatus 100A in the configurations of control unit 7 and ink supply unit 8. The other configurations are common to image forming apparatus 100A and image forming apparatus 100B. Below, only the configurations of image forming apparatus 100B that are different from image forming apparatus 100A will be described.

[0094] As shown in FIG. 8, the ink supply unit 8 of the image forming apparatus 100B further includes a heat medium container 85, a heat medium supply path 86, and a third pump 87.

[0095] The heat medium containing portion 85 contains the heat medium M1.

[0096] The heat medium supply path 86 is a flow path for the heat medium M1 provided between the heat medium storage unit 85 and the container 72 of the heating device 63. The heat medium supply path 86 is made of a flexible material. For example, the heat medium supply path 86 is a resin tube.

[0097] The third pump 87 is provided in the heat medium supply path 86. The third pump 87 causes the heat medium M1 in the heat medium supply path 86 to flow toward the heating device 63 side.

[0098] 7, 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. An apparatus including the control unit 7 and the heating device 63 is another example of the heating device of the present invention.

[0099] Specifically, a second operation control program for causing the CPU 51 of the control unit 7 to function as each of 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 executes the second operation control program stored in the ROM 52 to function as each of the above-mentioned functional units.

[0100] The function of drive control unit 91 is the same as that of drive control unit 91 included in image forming apparatus 100A.

[0101] The determination processing unit 94 determines, based on the first detected temperature after the heater 73 starts to be driven, whether or not the amount of the heat medium M1 contained in the container 72 falls below the lower limit amount, that is, the heat medium shortage state.

[0102] For example, the judgment processing unit 94 judges that the heat medium is insufficient when the increase in the first detected temperature from when the heater 73 starts to be driven until a predetermined reference time has elapsed is equal to or less than a predetermined threshold value.

[0103] When the determination processing unit 94 determines that the heat medium is insufficient, the first notification processing unit 95 issues a notification to that effect.

[0104] For example, the first notification processor 95 causes the operation display unit 5 to display a message indicating that the heat medium is insufficient.

[0105] Moreover, the first notification processor 95 limits the execution of the image forming process.

[0106] In addition, in image forming apparatus 100B, even after it is determined that the heat medium is insufficient, drive control unit 91 continues to drive and control heater 73 in order to determine whether the heat medium shortage state has been resolved by supplying heat medium M1.

[0107] The supply processing unit 96 supplies the heat medium M1 to the container 72 when the determination processing unit 94 determines that the heat medium is insufficient.

[0108] Specifically, the supply processing unit 96 drives the third pump 87 to supply the heat medium M1 contained in the heat medium containing unit 85 to the container 72.

[0109] For example, the supply processing unit 96 supplies the heat medium M1 to the container 72 until it is determined that the heat medium shortage state has been resolved based on the first detected temperature.

[0110] For example, the determination processing unit 94 determines that the heat medium shortage state has been resolved when the amount of increase in the first detected temperature from the start of supply of the heat medium M1 to the container 72 exceeds the threshold value. The supply processing unit 96 stops the supply of the heat medium M1 to the container 72 when the determination processing unit 94 determines that the heat medium shortage state has been resolved.

[0111] In addition, when it is determined that the heat medium is insufficient, the control unit 7 may lower the target temperature by a predetermined specific amount so that the duty ratio of the PWM signal becomes less than 100 percent until it is determined that the heat medium insufficient state is resolved. For example, the specific amount may be set based on the internal temperature of the image forming apparatus 100B. In addition, the control unit 7 may obtain the time required for the temperature of the heat medium M1 to reach the target temperature based on the first detected temperature when it is determined that the heat medium insufficient state is resolved, and notify the user of the obtained time. This allows the user to recognize the waiting time until the first detected temperature reaches the target temperature, that is, the waiting time until the execution of the image forming process is started.

[0112] The supply processing unit 96 may also supply a predetermined amount of the heat medium M1 to the container 72.

[0113] [Second operation control process] Hereinafter, an example of the procedure of the second operation 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 will be described with reference to Fig. 9. The second operation control process is executed when the drive control of the heater 73 is started by the drive control unit 91.

[0114] <Step S21> First, in step S21, the control unit 7 executes a first determination process to determine whether or not the heating medium is insufficient state, based on the first detected temperature after starting the driving of the heater 73. Here, the process of step S21 is an example of a determination step of the present invention, and is executed by the determination processing unit 94 of the control unit 7.

[0115] Specifically, the control unit 7 determines that the heating medium is insufficient when the amount of increase in the first detected temperature from when the heater 73 starts to be driven until the reference time has elapsed is equal to or less than the threshold value.

[0116] <Step S22> In step S22, the control unit 7 switches the subsequent process depending on the result of the process of step S21. Specifically, when the process of step S21 determines that the heat medium is insufficient (Yes side of S22), the control unit 7 shifts the process to step S23. On the other hand, when the process of step S21 does not determine that the heat medium is insufficient (No side of S22), the control unit 7 ends the second operation control process.

[0117] <Step S23> In step S23, the control unit 7 executes a first notification process for notifying the user that the heat medium is insufficient. The control unit 7 also limits the execution of the image forming process. Here, the process of step S23 is executed by the first notification process unit 95 of the control unit 7.

[0118] For example, the control unit 7 causes a message indicating that the heat medium is insufficient to be displayed on the operation display unit 5. This allows the user of the image forming apparatus 100B to recognize that the execution of the image forming process is restricted due to the heat medium insufficient state.

[0119] It should be noted that the control unit 7 continues to control the drive of the heater 73 by the drive control unit 91 even after it is determined that the heat medium is insufficient.

[0120] <Step S24> In step S24, the control unit 7 executes a supply process to supply the heat medium M1 to the container 72. Here, the process of step S24 is executed by the supply process unit 96 of the control unit 7.

[0121] Specifically, the control unit 7 supplies the heat medium M1 to the container 72 until it is determined that the heat medium shortage state has been resolved based on the first detected temperature. This makes it possible to more reliably resolve the heat medium shortage state, compared to a configuration in which a predetermined amount of heat medium M1 is supplied to the container 72.

[0122] When the heat medium shortage state is resolved, the control unit 7 may release the restriction on the execution of the image forming process.

[0123] 5, in image forming apparatus 100B, first temperature sensor 75 is provided in container 72 above spiral portion 82 of coiled tube 71. This makes it possible to use first temperature sensor 75 to determine whether the amount of heat medium M1 contained in container 72 has decreased due to evaporation or leakage.

[0124] [Third embodiment] Next, a configuration of an image forming apparatus 100C according to a third embodiment of the present invention will be described with reference to FIG.

[0125] Image forming apparatus 100C differs from image forming apparatus 100B in the configurations of control unit 7 and warming device 63. The other configurations are common to image forming apparatus 100B and image forming apparatus 100C. Hereinafter, only the configurations of image forming apparatus 100C that are different from image forming apparatus 100B will be described.

[0126] The warming device 63 of the image forming apparatus 100C further includes a water level sensor 78 shown in FIG.

[0127] The water level sensor 78 detects the water level of the heat medium M1 in the container 72. For example, the water level sensor 78 is a so-called float sensor. The water level sensor 78 has a floating part that floats on the water surface of the heat medium M1 contained in the container 72, and detects the water level of the heat medium M1 using the floating part. When the water level of the heat medium M1 contained in the container 72 falls below a lower limit position P1 (see FIG. 5), the water level sensor 78 outputs a third detection signal indicating that fact.

[0128] 10, 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. An apparatus including the control unit 7 and the heating device 63 is another example of the heating device of the present invention.

[0129] Specifically, a third operation control program for causing the CPU 51 of the control unit 7 to function as each of 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 executes the third operation control program stored in the ROM 52 to function as each of the above-mentioned functional units.

[0130] The functions of the drive control unit 91 and the first notification processing unit 95 are the same as those of the drive control unit 91 and the first notification processing unit 95 included in the image forming apparatus 100B.

[0131] The judgment processing unit 94 judges whether or not the amount of heat medium M1 contained in the container 72 is below the lower limit amount, based on the detection result by the water level sensor 78 and the first detected temperature after the heater 73 starts to operate, and thus the heat medium shortage state.

[0132] For example, the determination processing unit 94 determines that the heating medium is insufficient when the increase in the first detected temperature from when the heater 73 starts to be driven until the reference time has elapsed is equal to or less than the threshold value.

[0133] Furthermore, when the third detection signal is output from the water level sensor 78, the determination processing unit 94 determines that the heat medium is insufficient.

[0134] In addition, the judgment processing unit 94 judges that the heat transfer medium is not in a shortage state when it is not judged that the heat transfer medium is in a shortage state based on the detection result by the water level sensor 78, and when it is not judged that the heat transfer medium is in a shortage state based on the first detected temperature after the heater 73 starts to operate.

[0135] Here, the determination processing unit 94 determines that the water level sensor 78 or the first temperature sensor 75 is malfunctioning when the determination result based on the detection result by the water level sensor 78 differs from the determination result based on the first detected temperature after the start of driving of the heater 73. Specifically, the determination processing unit 94 determines that of the water level sensor 78 and the first temperature sensor 75, the sensor that is determined not to be in the heat medium shortage state based on the detection result is malfunctioning.

[0136] The determination processing unit 94 may determine whether or not there is a shortage of the heat medium based only on the detection result by the water level sensor 78 .

[0137] The supply processing unit 96 supplies the heat medium M1 to the container 72 when the determination processing unit 94 determines that the heat medium is insufficient.

[0138] Specifically, the supply processing unit 96 drives the third pump 87 to supply the heat medium M1 contained in the heat medium containing unit 85 to the container 72.

[0139] For example, the supply processing unit 96 supplies the heat medium M1 to the container 72 until it is determined that the heat medium shortage state has been resolved based on the detection result by the water level sensor 78.

[0140] For example, the determination processing unit 94 determines that the heat medium shortage state has been resolved when the third detection signal is no longer output from the water level sensor 78. The supply processing unit 96 stops the supply of the heat medium M1 to the container 72 when the determination processing unit 94 determines that the heat medium shortage state has been resolved.

[0141] When the determination processing unit 94 determines that the water level sensor 78 or the first temperature sensor 75 is malfunctioning, the second notification processing unit 97 issues a notification to that effect.

[0142] For example, the second notification processing unit 97 causes the operation and display unit 5 to display a message indicating that the water level sensor 78 or the first temperature sensor 75 has failed.

[0143] [Third operation control process] Hereinafter, 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 will be described with reference to Fig. 11. The third operation control process is executed when the drive control of the heater 73 is started by the drive control unit 91.

[0144] <Step S31> First, in step S31, the control unit 7 executes a second determination process to determine whether or not the amount of heat medium M1 contained in the container 72 is below the lower limit amount, that is, the heat medium shortage state, based on the detection result by the water level sensor 78 and the first detected temperature after starting the operation of 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.

[0145] Specifically, the control unit 7 determines that the heat medium shortage state exists when the amount of increase in the first detected temperature from when the heater 73 starts to be driven until the reference time has elapsed is equal to or less than the threshold value. Furthermore, the control unit 7 determines that the heat medium shortage state exists when the third detection signal is output from the water level sensor 78. Furthermore, the control unit 7 determines that the heat medium shortage state does not exist when the control unit 7 does not determine that the heat medium shortage state exists based on the detection result by the water level sensor 78 and when the control unit 7 does not determine that the heat medium shortage state exists based on the first detected temperature after the heater 73 starts to be driven.

[0146] <Step S32> In step S32, the control unit 7 switches the subsequent process depending on the result of the process of step S31. Specifically, when the process of step S31 determines that the heat medium is insufficient (Yes side of S32), the control unit 7 shifts the process to step S33. On the other hand, when the process of step S31 does not determine that the heat medium is insufficient (No side of S32), the control unit 7 ends the third operation control process.

[0147] <Step S33> In step S33, the control unit 7 executes the first notification process for notifying the user that the heat medium is insufficient. The control unit 7 also limits 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.

[0148] <Step S34> In step S34, the control unit 7 executes the supply process for supplying the heat medium M1 to the container 72. Here, the process of step S34 is executed by the supply process unit 96 of the control unit 7.

[0149] Specifically, the control unit 7 supplies the heat medium M1 to the container 72 until it is determined that the heat medium shortage state has been resolved based on the detection result by the water level sensor 78.

[0150] When the heat medium shortage state is resolved, the control unit 7 may release the restriction on the execution of the image forming process.

[0151] <Step S35> In step S35, the control unit 7 switches the subsequent process depending on the result of the process of step S31. Specifically, when the determination result based on the detection result by the water level sensor 78 in the process of step S31 is different from the determination result based on the first detected temperature after the heater 73 starts to be driven (Yes side of S35), the control unit 7 shifts the process to step S36. Also, when the determination result based on the detection result by the water level sensor 78 in the process of step S31 is the same as the determination result based on the first detected temperature after the heater 73 starts to be driven (No side of S35), the control unit 7 ends the third operation control process.

[0152] <Step S36> In step S36, the control unit 7 issues a notification that there is a malfunction in the water level sensor 78 or the first temperature sensor 75. The process of step S36 is executed by the second notification processing unit 97 of the control unit 7.

[0153] Specifically, when it is not determined in the process of step S31 that the heat medium is insufficient based on the detection result by the water level sensor 78, the control unit 7 causes the operation display unit 5 to display a message indicating that the water level sensor 78 is malfunctioning. Also, when it is not determined in the process of step S31 that the heat medium is insufficient based on the first detected temperature after the heater 73 starts to be driven, the control unit 7 causes the operation display unit 5 to display a message indicating that the first temperature sensor 75 is malfunctioning. This allows the user of image forming apparatus 100C to take action, such as replacing the malfunctioning sensor.

[0154] In this manner, the image forming apparatus 100C is provided with a water level sensor 78 that detects the water level of the heat medium M1 in the container 72. This makes it possible to determine whether the amount of the heat medium M1 contained in the container 72 has decreased due to evaporation or leakage.

[0155] [Notes on the invention] The following will provide an overview of the invention extracted from the above-described embodiment. Note that the configurations and processing functions described in the following supplementary notes can be selected and combined as desired.

[0156] <Appendix 1> a heater for heating the storage unit; a contact-type temperature sensor provided above the spiral portion within the storage unit and used to detect the temperature of the heat medium; a drive control unit for controlling the operation of the heater based on a detected temperature detected by the temperature sensor; and a judgment processing unit for determining whether or not the amount of the heat medium contained in the storage unit is below a predetermined lower limit amount, i.e., a heat medium shortage state, based on the detected temperature after the heater starts to be driven.

[0157] <Appendix 2> 2. The heating device according to claim 1, further comprising a notification processing unit that, when the determination processing unit determines that the heat medium is insufficient, notifies the user of that effect.

[0158] <Appendix 3> 3. The heating device according to claim 1 or 2, further comprising a supply processing unit that supplies the heat medium to the storage unit when the determination processing unit determines that the heat medium is insufficient.

[0159] <Appendix 4> The heating device according to claim 3, wherein the supply processing unit supplies the heat medium to the storage unit until it is determined that the heat medium shortage state is resolved based on the detected temperature.

[0160] <Appendix 5> 5. An image forming apparatus comprising the heating device according to any one of claims 1 to 4, and forming an image using ink heated by the heating device.

[0161] <Appendix 6> A determination method executed by a heating device comprising: a coiled tube having a helical portion formed in a spiral shape, a storage portion that stores the helical portion and a liquid heat medium used to heat the helical portion, a heater that heats the storage portion, a contact-type temperature sensor that is provided above the helical portion in the storage portion and is used to detect the temperature of the heat medium, and a drive control portion that controls the drive of the heater based on the detected temperature detected by the temperature sensor, the determination method including a determination step that determines whether or not the amount of the heat medium contained in the storage portion is below a predetermined lower limit amount, that is, a heat medium shortage state, based on the detected temperature after the heater starts to be driven. [Explanation of symbols]

[0162] 1 Case 2 Sheet transport section 3. Image forming section 4 Transport unit 5 Operation display section 6 Memory section 7 Control section 8 Ink supply unit 30 Recording head 61 Ink Container 62 1st supply route 63 Warming device 64 First Pump 65 Sub ink tank 66 2nd supply route 67 Second Pump 71 Snake pipe 72 Container 73 Heater 74 Insulation 75 First temperature sensor 76 Second temperature sensor 77 Thermostat 78 Water Level Sensor 82 Spiral part 91 Drive control unit 92 Stop processing section 93 Acquisition processing unit 94 Judgment processing unit 95 First notification processing unit 96 Supply Processing Section 97 Second notification processing unit 100A Image forming device 100B Image forming device 100C image forming device

Claims

1. A coiled tube having a helical portion formed in a helical shape; a storage section for storing the spiral portion and a liquid heat medium used to heat the spiral portion; A heater for heating the storage unit; a contact-type temperature sensor provided in the storage section above the spiral section and used to detect the temperature of the heat transfer medium; a drive control unit that controls driving of the heater based on a detected temperature detected by the temperature sensor; a determination processing unit that determines whether or not a heat medium shortage state occurs in which an amount of the heat medium contained in the container falls below a predetermined lower limit amount based on the detected temperature after the heater starts to be driven; A heating device comprising:

2. A notification processing unit is provided that notifies the user when the determination processing unit determines that the heat medium is insufficient. The warming device according to claim 1 .

3. A supply processing unit is provided for supplying the heat medium to the storage unit when the determination processing unit determines that the heat medium is insufficient. The warming device according to claim 1 .

4. The supply processing unit supplies the heat medium to the accommodation unit until it is determined that the heat medium shortage state is resolved based on the detected temperature. The warming device according to claim 3.

5. Equipped with the heating device according to any one of claims 1 to 4, forming an image using the ink heated by the heating device; Image forming device.

6. A determination method executed by a heating device including: a coiled tube having a helical portion formed in a helical shape; a storage portion that stores the helical portion and a liquid heat medium used to heat the helical portion; a heater that heats the storage portion; a contact-type temperature sensor that is provided above the helical portion in the storage portion and is used to detect the temperature of the heat medium; and a drive control portion that controls the drive of the heater based on a detection temperature detected by the temperature sensor, A determination step of determining whether or not a heat medium shortage state occurs in which an amount of the heat medium contained in the container falls below a predetermined lower limit amount based on the detected temperature after the heater starts to be driven. Judgment method.

Images