Heating device and heating control method

Abstract

A heating device and a heating control method are disclosed, which can prevent damage to a fixing belt. The heating device of an embodiment includes a fixing belt, a pressure roller, a heating portion, a driving portion, a current measuring portion, and a control portion. The fixing belt is annular and is supported so as to be movable in rotation. The pressure roller abuts against an outer side of the fixing belt. The heating portion heats the fixing belt. The driving portion causes the fixing belt to rotate as a driven body by causing the pressure roller to rotate. The current measuring portion measures a driving current in the driving portion. The control portion causes the heating portion to stop heating on the basis of a measurement result of the driving current measured by the current measuring portion.

Description

Technical Field

[0001] The embodiments of the present invention relate to a heating device and a heating control method. Background Technology

[0002] An on-demand heating device, such as a film fixing device, is provided. The on-demand heating device is installed in an image forming apparatus, such as an MFP (Multifunction Peripheral). In a typical on-demand heating device, an annular fixing belt (tubular film) supported for rotatable movement rotates driven by the rotation of a pressure roller that abuts against the fixing belt. Lubricant is applied to the fixing belt and a sliding surface with a support portion that supports the inner circumferential surface of the fixing belt as slidable. As the fixing belt rotates, the remaining amount of lubricant gradually decreases, and due to the decrease in the remaining amount, rotation of the fixing belt becomes difficult. To address this, the decrease in the remaining amount of lubricant is determined by detecting an increase in the load torque in the drive motor that rotates the pressure roller, and an alarm is generated.

[0003] In on-demand heating devices, when the fuser belt stops rotating, the temperature near the heating section used to heat the belt sometimes rises sharply. This is because the stopping of the fuser belt's rotation causes the paper to stop passing between the fuser belt and the pressure roller, preventing the heat near the heating section from being carried away by the paper. Additionally, the stopping of the fuser belt's rotation is mainly caused by a decrease in the remaining amount of lubricant or poor contact between the fuser belt and the pressure roller. When the temperature near the heating section rises sharply, the fuser belt and other components may be damaged.

[0004] In the aforementioned prior art, when an increase in load torque in the drive motor is detected, the temperature near the heating element may have already reached a level sufficient to damage the fixing belt, etc. Furthermore, in the aforementioned prior art, it is impossible to detect a stop in the rotation of the fixing belt caused by poor contact between the fixing belt and the pressure roller. Conventionally, there has been a problem of equipment damage due to such a rapid increase in temperature near the heating element. Summary of the Invention

[0005] The problem this invention aims to solve is to prevent equipment damage caused by a rapid increase in temperature in the heating element.

[0006] According to one aspect of the embodiment, a heating device is provided, comprising a fixing belt, a pressure roller, a heating unit, a driving unit, a current measuring unit, and a control unit. The fixing belt is annular and supported for rotatable movement. The pressure roller abuts against the outer side of the fixing belt. The heating unit heats the fixing belt. The driving unit rotates the fixing belt by rotating the pressure roller. The current measuring unit measures the driving current in the driving unit. Based on the measurement result of the driving current measured by the current measuring unit, the control unit stops the heating unit from heating.

[0007] According to another aspect of the embodiments, a heating control method is provided, characterized in that a pressure roller abutting against the outside of an annular fixing belt is rotated by a driving unit, thereby causing the fixing belt to rotate passively, the fixing belt being supported to be rotatably movable, the fixing belt being heated by the heating unit, and the heating unit stopping heating based on the measurement result of the driving current in the driving unit. Attached Figure Description

[0008] Figure 1 This is a schematic structural diagram of the image processing apparatus according to the first embodiment.

[0009] Figure 2 This is a hardware structure diagram of the image processing apparatus according to the first embodiment.

[0010] Figure 3 This is a front sectional view of the heating device according to the first embodiment.

[0011] Figure 4 This is a front sectional view of the heater unit according to the first embodiment.

[0012] Figure 5 This is a bottom view of the heater unit according to the first embodiment.

[0013] Figure 6 This is a top view of the heater thermometer and thermostat according to the first embodiment.

[0014] Figure 7 This is a circuit diagram of the heating device according to the first embodiment.

[0015] Figure 8 This is a front sectional view of another structure of the heating device according to the first embodiment.

[0016] Figure 9 This is an excerpted block diagram of the main components of a heating device for heating control according to the first embodiment.

[0017] Figure 10 This is a flowchart illustrating the operation of the heating device in the anomaly detection process according to the first embodiment.

[0018] Figure 11 This is a diagram showing the temperature distribution of the heating device according to an embodiment of the second embodiment.

[0019] Figure 12 This is a diagram showing the temperature progression of the heating device according to an embodiment of the second embodiment.

[0020] Figure 13 This is an excerpted block diagram of the main components of a heating device for heating control according to the second embodiment.

[0021] Figure 14 This is a flowchart illustrating the operation of the heating device in the anomaly detection process according to the second embodiment.

[0022] Explanation of reference numerals in the attached figures

[0023] 1…Image forming apparatus; 2…Scanner section; 3…Image forming unit; 4…Paper supply section; 5…Conveyor section; 6, 6-1…Control section; 7…Paper tray; 8…Control panel; 9…Flipping unit; 10…Housing; 20…Paper storage section; 21…Pick-up roller; 23…Conveyor roller; 24…Alignment roller; 25…Image forming section; 25-1 to 25-4…Image forming section; 26…Laser scanning unit; 27…Intermediate… 28…Transfer belt; 30, 300…Fixing device; 30-1…Pressure roller; 30-2…Film unit; 32…Core rod; 33…Elastic layer; 34…Release layer; 35…Cylindrical film; 36…Support component; 38…Straight bar; 40…Heater unit; 41…Substrate; 43…Insulating layer; 45…Heating element assembly; 45-1…Central heating element; 45-2…First end heating element; 45-3…Second end heating element Heating element; 46…protective layer; 49…heat transfer component; 52-1…center contact; 52-2…end contact; 53-1…center wiring; 53-2…first end wiring; 53-3…second end wiring; 55…wiring group; 57…common wiring; 58…common contact; 62…heater thermometer; 62-1…center heater thermometer; 62-2…end heater thermometer; 64…film thermometer; 64-1…center film thermometer; 64-2…end film thermometer; 68…thermostat; 68-1…center thermostat; 68-2…end thermostat; 70…motor; 71…drive force transmission component; 72…current sensor; 90…communication unit; 92…memory; 93…auxiliary storage device; 95…power supply; 96-1…center three-terminal bidirectional thyristor switch element; 96-2 end three-terminal bidirectional thyristor switch element. Detailed Implementation

[0024] Hereinafter, the heating apparatus and heating control method of the embodiments will be described with reference to the accompanying drawings.

[0025] (First Implementation)

[0026] Figure 1 This is a schematic structural diagram of the image processing apparatus according to the first embodiment.

[0027] The image processing apparatus of the first embodiment is an image forming apparatus 1. The image forming apparatus 1 performs processing for forming an image on a piece of paper S. The paper S is, for example, paper, label paper, etc. The paper S can be any type of paper, as long as the image forming apparatus 1 can form an image on its surface.

[0028] The image forming apparatus 1 includes a housing 10, a scanner unit 2, an image forming unit 3, a paper supply unit 4, a conveying unit 5, a paper discharge tray 7, a flipping unit 9, a control panel 8, and a control unit 6.

[0029] The housing 10 forms the external shape of the image forming apparatus 1.

[0030] The scanner unit 2 reads the image information of the object to be copied as the brightness of light and darkness, and generates an image signal. The scanner unit 2 outputs the generated image signal to the image forming unit 3.

[0031] The image forming unit 3 forms an output image (hereinafter referred to as a "toner image") based on an image signal input from the scanner unit 2 or an externally input image signal, using a recording agent such as a toner. The image forming unit 3 transfers the toner image onto the surface of the paper S. The image forming unit 3 heats and presses the toner image transferred onto the surface of the paper S to fix the toner image onto the paper S. Details of the image forming unit 3 will be described later.

[0032] The paper supply unit 4 supplies sheets of paper S one by one to the transport unit 5 in coordination with the timing of the toner image formation by the image forming unit 3. The paper supply unit 4 includes a paper storage unit 20 and a pickup roller 21.

[0033] The paper storage section 20 stores papers of predetermined size and type.

[0034] Pick-up roller 21 picks up sheets of paper S one by one from paper storage section 20. Pick-up roller 21 supplies the picked-up sheets of paper S to conveyor section 5.

[0035] Furthermore, the paper S for forming the image can be not only the paper stored in the paper storage section 20, but also the paper manually inserted into the image forming apparatus 1.

[0036] The transport unit 5 transports the paper S supplied from the paper supply unit 4 to the image forming unit 3. The transport unit 5 has a transport roller 23 and a registration roller 24.

[0037] The conveyor roller 23 conveys the paper S supplied from the pick-up roller 21 to the alignment roller 24. The conveyor roller 23 causes the leading edge of the paper S in the conveying direction to abut against the gap of the alignment roller 24.

[0038] The alignment roller 24 adjusts the leading edge position of the paper S in the conveying direction by flexing the paper S in the roller gap. The alignment roller 24 conveys the paper S according to the timing of the toner image transfer to the paper S by the image forming unit 3.

[0039] The image forming unit 3 is described.

[0040] The image forming unit 3 has multiple image forming sections 25, a laser scanning unit 26, an intermediate transfer belt 27, a transfer section 28, and a fixing device 30.

[0041] The image forming unit 25 has a photosensitive drum D. The image forming unit 25 forms a toner image on the photosensitive drum D that corresponds to an image signal from the scanner unit 2 or an external source. Multiple image forming units 25 (image forming units 25-1, 25-2, 25-3, and 25-4) form toner images using yellow, magenta, cyan, and black toners, respectively.

[0042] Chargers (not shown), developers (not shown), and other components are arranged around the photosensitive drum D. The chargers charge the surface of the photosensitive drum D. The developers contain toners including yellow, magenta, cyan, and black. The developers develop the electrostatic latent image on the photosensitive drum D. The result is a toner image of various colors of toner formed on the photosensitive drum D.

[0043] The laser scanning unit 26 scans the charged photosensitive drum D with a laser L to expose the photosensitive drum D. The laser scanning unit 26 exposes the photosensitive drums D of the image forming units 25 (image forming units 25-1, 25-2, 25-3, 25-4) of various colors with different lasers (lasers LY, LM, LC, LK). As a result, the laser scanning unit 26 forms an electrostatic latent image on the photosensitive drum D.

[0044] The toner image on the surface of the photosensitive drum D is transferred to the intermediate transfer belt 27 in one pass.

[0045] The transfer unit 28 transfers the toner image that was first transferred to the intermediate transfer belt 27 onto the surface of the paper S at the secondary transfer position.

[0046] The fixing device 30 heats and pressurizes the toner image transferred onto the paper S, and fixes the toner image onto the paper S. Details of the fixing device 30 will be described later.

[0047] The flipping unit 9 flips the paper S to form an image on the reverse side of the paper S. The flipping unit 9 flips the front and back sides of the paper S discharged from the fixing device 30 by folding it back. The flipping unit 9 conveys the flipped paper S toward the registration roller 24.

[0048] The paper S that has been ejected after the image is formed is placed on the paper tray 7.

[0049] The control panel 8 is part of the input section for inputting information for the operator to operate the image forming apparatus 1. The control panel 8 has a touch panel and various physical keys.

[0050] The control unit 6 controls the various parts of the image forming apparatus 1. Details of the control unit 6 will be described later.

[0051] Figure 2 This is a hardware structure diagram of an image processing apparatus according to the first embodiment. The image forming apparatus 1 includes a CPU (Central Processing Unit) 91, a memory 92, an auxiliary storage device 93, etc., connected via a bus to execute a program. By executing the program, the image forming apparatus 1 functions as a device including a scanner unit 2, an image forming unit 3, a paper supply unit 4, a transport unit 5, a flipping unit 9, a control panel 8, and a communication unit 90.

[0052] The CPU 91 functions as the control unit 6 by executing programs stored in the memory 92 and auxiliary storage device 93. The control unit 6 controls the operation of each functional unit of the image forming apparatus 1.

[0053] The auxiliary storage device 93 is constructed using a storage device such as a magnetic hard disk drive or a semiconductor storage device. The auxiliary storage device 93 stores information.

[0054] The communication unit 90 is configured to include a communication interface for connecting the communication unit 90 to an external device. The communication unit 90 communicates with the external device through the communication interface.

[0055] The fixing device 30 is described in detail.

[0056] Figure 3 This is a front sectional view of the heating device according to the first embodiment. The heating device in the first embodiment is a fixing device 30. The fixing device 30 has a pressure roller 30-1 and a film unit 30-2.

[0057] A gap N is formed between the pressure roller 30-1 and the film unit 30-2. The pressure roller 30-1 applies pressure to the toner image formed on the surface of the paper S that enters the gap N. The pressure roller 30-1 rotates to transport the paper S. The pressure roller 30-1 has a core 32, an elastic layer 33, and a release layer 34.

[0058] The mandrel 32 is formed into a cylindrical shape from a metal material such as stainless steel. The two ends of the mandrel 32 in the axial direction are supported and are rotatable. Figure 9 The rotational force generated by the motor 70 (drive unit) is transmitted to the mandrel 32 through the drive force transmission member 71, thereby driving the mandrel 32 to rotate. Driven by the rotation of the mandrel 32, the pressure roller 30-1 rotates, and the tubular film 35 (fixing belt) rotates accordingly.

[0059] The mandrel 32 abuts against the cam component (not shown). The cam component (not shown) rotates to bring the mandrel 32 close to and separate it from the membrane unit 30-2.

[0060] The elastic layer 33 is formed of an elastic material such as silicone rubber. The elastic layer 33 is formed on the outer peripheral surface of the mandrel 32 with a certain thickness.

[0061] Release layer 34 is formed of a resin material such as PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer). Release layer 34 is formed on the outer peripheral surface of elastic layer 33.

[0062] For example, when the outer diameter of the pressure roller 30-1 is 20 mm to 40 mm, preferably, the outer diameter of the mandrel 32 is set to 10 mm to 20 mm, the thickness of the elastic layer 33 is set to 5 mm to 20 mm, and the thickness of the release layer 34 is set to 20 μm to 40 μm.

[0063] In the ASKER-C hardness tester, under a load of 9.8 N, the hardness of the outer peripheral surface of the pressure roller 30-1 is preferably 40° to 70°. This ensures the area of ​​the roll gap N and the durability of the pressure roller 30-1.

[0064] The pressure roller 30-1 can approach or separate from the film unit 30-2 by rotating the cam member. When the pressure roller 30-1 is brought close to the film unit 30-2 and pressed by the pressure plate (not shown), a roller gap N is formed. On the other hand, when a paper jam occurs in the fixing device 30, the paper S can be easily removed by separating the pressure roller 30-1 from the film unit 30-2. In addition, when the rotation of the tubular film 35 is stopped, for example during sleep, plastic deformation (creep) of the pressure roller 30-1 and the tubular film 35 is prevented by separating the pressure roller 30-1 from the film unit 30-2.

[0065] Additionally, for example, the pressure plate is preferably adjusted so that the contact pressure between the membrane unit 30-2 and the pressure roller 30-1 is 300N to 500N under the total pressure.

[0066] At both ends of the mandrel 32 along its long side, the pressure rollers 30-1 are supported and rotatable between the side plates (not shown) of the device frame via various bearing components (not shown). The rotational force generated by the motor 70 (drive unit) is transmitted through the drive force transmission component 71, thereby driving the pressure rollers 30-1 to rotate. When the pressure rollers 30-1 rotate in the state forming the nip N, the cylindrical film 35 of the film unit 30-2 rotates consequently. The pressure rollers 30-1 rotate with the paper S positioned in the nip N, thereby conveying the paper S in the conveying direction W.

[0067] Image of toner in paper S heated by film unit 30-2 entering roll gap N. Film unit 30-2 has a tubular film (tubular body) 35, heater unit 40, support member 36, support bar 38, heater thermometer 62, thermostat 68 and film thermometer 64.

[0068] The tubular film 35 (fixing belt) is formed in a tubular shape and has an annular outer peripheral surface. From its inner peripheral side, the tubular film 35 sequentially comprises a base layer composed of sheet-like components with high heat resistance, an elastic layer for improving fixing performance, and a release layer as the outermost layer. The base layer is formed into a tubular shape from a metallic material such as nickel (Ni) or stainless steel. The elastic layer is laminated and disposed on the outer peripheral surface of the base layer. The elastic layer is formed from an elastic material such as silicone rubber. The release layer is laminated and disposed on the outer peripheral surface of the elastic layer. The release layer is formed from a material such as PFA resin.

[0069] To shorten the preheating time, the thicknesses of the elastic layer and the release layer are preferably set so that their respective heat capacities are not too large. For example, when the inner diameter of the cylindrical film 35 is 20 mm to 40 mm, the thickness of the base layer is set to 30 μm to 50 μm, the thickness of the elastic layer is set to 10 μm to 300 μm, and the thickness of the release layer is set to 20 μm to 40 μm.

[0070] The inner side of the base layer may be coated with a coating to improve the frictional sliding properties with the heater unit 40.

[0071] Figure 4 yes Figure 5 A front sectional view of the heater unit on line IV-IV. Figure 5 This is a bottom view of the heater unit (viewed from the +z direction). The heater unit 40 has a substrate 41, a heating element assembly 45, and a wiring assembly 55.

[0072] The substrate 41 (heat-generating substrate) is formed of a metal material such as stainless steel or a ceramic material such as aluminum nitride. The substrate 41 is formed into an elongated rectangular plate shape. The substrate 41 is disposed radially inside the cylindrical film 35. The axial direction of the cylindrical film 35 is taken as the long side direction of the substrate 41.

[0073] In this application, the x-direction, y-direction, and z-direction are defined as follows.

[0074] The y-direction is the direction of the long side of the substrate 41 (heater unit 40). As described below, the +y-direction is the direction from the central heating element 45-1 toward the first end heating element 45-2.

[0075] The x-direction is the direction of the short side of substrate 41. The +x-direction is the transport direction of paper S (the direction on the downstream side).

[0076] The z-direction is the normal direction of the substrate 41. The +z-direction is the direction in which the heating element assembly 45 is positioned relative to the substrate 41. The insulating layer 43 is formed on the surface of the substrate 41 in the +z-direction by a glass material or the like. The surface of the heater unit 40 in the +z-direction (first surface 40-1) and the cylindrical film 35 (see reference) Figure 3 ) is in contact with the inner peripheral surface.

[0077] The heating element assembly 45 is disposed on the substrate 41. For example... Figure 4 As shown, the heating element assembly 45 is formed on the surface of the insulating layer 43 in the +z direction. The heating element assembly 45 is formed of a silver, palladium alloy, or the like. The external shape of the heating element assembly 45 is rectangular, with the y-direction being the long side direction and the x-direction being the short side direction. The heating element assembly 45 is formed, for example, by screen printing.

[0078] like Figure 5 As shown, the heating element assembly 45 has a first end heating element 45-2, a central heating element 45-1, and a second end heating element 45-3 arranged along the y-direction. The heating element assembly 45 has a first end heating element 45-2, a central heating element 45-1, and a second end heating element 45-3 arranged side by side in the y-direction.

[0079] In addition, in this embodiment, a heating element group 45 consisting of multiple heating elements is used, but a single heating element can also be used.

[0080] The central heating element 45-1 is located at the center of the heating element assembly 45 in the y-direction. The central heating element 45-1 can be constructed by combining multiple small heating elements arranged side by side in the y-direction.

[0081] The first end heating element 45-2 is disposed at the end of the central heating element 45-1 in the +y direction and at the end of the heating element assembly 45 in the +y direction.

[0082] The second end heating element 45-3 is disposed at the end of the heating element assembly 45 in the -y direction of the central heating element 45-1 and in the -y direction.

[0083] The boundary line between the central heating element 45-1 and the first end heating element 45-2 is arranged parallel to the x-direction. Alternatively, the boundary line between the central heating element 45-1 and the first end heating element 45-2 can be arranged to intersect the x-direction. The boundary line between the central heating element 45-1 and the second end heating element 45-3 is also the same.

[0084] The heating element assembly 45 generates heat when energized. The resistance value of the central heating element 45-1 is less than the resistance values ​​of the first end heating element 45-2 and the second end heating element 45-3. The resistance values ​​of the first end heating element 45-2 and the second end heating element 45-3 are approximately the same. Here, the resistance value of the central heating element 45-1 is defined as "central resistance value A", and the resistance value of the first end heating element 45-2 (second end heating element 45-3) is defined as "end resistance value B". For example, preferably, the ratio (A:B) of the central resistance value A to the end resistance value B is in the range of 3:1 to 7:1, and more preferably in the range of 4:1 to 6:1.

[0085] A piece of paper S with a narrow width in the y-direction passes through the center portion of the fixing device 30 in the y-direction. In this case, the control unit 6 heats only the central heating element 45-1. On the other hand, when the paper S has a wide width in the y-direction, the control unit 6 heats the entire heating element assembly 45. Therefore, the heating of the central heating element 45-1, the first end heating element 45-2, and the second end heating element 45-3 is controlled to be independent of each other. Furthermore, the heating of the first end heating element 45-2 and the second end heating element 45-3 is controlled in the same manner.

[0086] Wiring assembly 55 is formed of a metallic material such as silver. Wiring assembly 55 has a central contact 52-1, a central wiring 53-1, an end contact 52-2, a first end wiring 53-2, a second end wiring 53-3, a common contact 58, and a common wiring 57.

[0087] The central contact 52-1 is positioned in the -y direction of the heating element assembly 45.

[0088] The central wiring 53-1 is configured in the +x direction of the heating element assembly 45. The central wiring 53-1 connects the end edge of the central heating element 45-1 in the +x direction to the central contact 52-1.

[0089] The end contact 52-2 is positioned in the -y direction of the central contact 52-1.

[0090] The first end wiring 53-2 is positioned in the +x direction of the heating element assembly 45 and in the +x direction of the center wiring 53-1. The first end wiring 53-2 connects the end edge of the first end heating element 45-2 in the +x direction to the end of the end contact 52-2 in the +x direction.

[0091] The second end wiring 53-3 is positioned in the +x direction of the heating element assembly 45 and in the -x direction of the center wiring 53-1. The second end wiring 53-3 connects the end edge of the second end heating element 45-3 in the +x direction to the end edge of the end contact 52-2 in the -x direction.

[0092] Common contact 58 is configured in the +y direction of heating element group 45.

[0093] A common wiring 57 is configured in the -x direction of the heating element assembly 45. The common wiring 57 connects the ends of the central heating element 45-1, the first end heating element 45-2, and the second end heating element 45-3 in the -x direction to the common contact 58.

[0094] As described above, the second end wiring 53-3, the central wiring 53-1, and the first end wiring 53-2 are arranged in the +x direction of the heating element assembly 45, while only the common wiring 57 is arranged in the -x direction of the heating element assembly 45. Therefore, the center 45-0 of the heating element assembly 45 in the x direction is arranged closer to the -x direction than the center 41-0 of the substrate 41 in the x direction.

[0095] like Figure 4 As shown, the heating element assembly 45 and the wiring assembly 55 are formed on the surface of the insulating layer 43 in the +z direction. A protective layer 46, formed of a glass material or the like, covers the heating element assembly 45 and the wiring assembly 55. The protective layer 46 protects the heating element assembly 45 and the wiring assembly 55. The protective layer 46 improves the sliding properties between the heater unit 40 and the cylindrical diaphragm 35.

[0096] like Figure 3 As shown, heater unit 40 is disposed inside cylindrical membrane 35. Lubricating oil (lubricant) is coated on the inner circumferential surface of cylindrical membrane 35. Heater unit 40 contacts the inner circumferential surface of cylindrical membrane 35 through lubricating oil. Lubricating oil is disposed on the first surface 40-1 of heater unit 40 (see reference). Figure 4 The lubricating oil is positioned between the heater unit 40 and the inner circumferential surface of the cylindrical membrane 35. When the heater unit 4 heats up, the viscosity of the lubricating oil decreases. This ensures smooth sliding between the heater unit 40 and the cylindrical membrane 35.

[0097] The support member 36 is made of a component with rigidity, heat resistance, and thermal insulation. The support member 36 is formed of elastic materials such as silicone rubber and fluororubber, and resin materials such as polyimide resin, PPS (polyphenylene sulfide), PES (polyethersulfone), and liquid crystal polymers. The heater unit 40 and the support member 36 are integrally formed. The support member 36 is configured to cover both sides of the heater unit 40 in the -z and x directions. The support member 36 supports the heater unit 40. Rounded chamfers are formed at both ends of the support member 36 in the x direction. The support member 36 has a generally semi-cylindrical cross-section. The support member 36 supports the inner circumferential surface of the cylindrical membrane 35 at both ends of the heater unit 40 in the x direction. Additionally, the support member 36 supports one side surface of the heater unit 40.

[0098] When the paper S passing through the fixing device 30 is heated, a temperature distribution is generated in the heater unit 40 according to the size of the paper S. When the temperature of the heater unit 40 locally rises, the temperature may exceed the heat resistance temperature of the support member 36 formed of resin material.

[0099] The support bar 38 is formed from a material such as steel plate. The cross-section of the support bar 38 perpendicular to the y-direction is U-shaped. For example, the support bar 38 is formed by bending steel material with a thickness of 1 mm to 3 mm. The support bar 38 is mounted in the -z direction of the support member 36 to allow the support member 36 to bend the U-shaped opening. The support bar 38 extends in the y-direction. The two ends of the support bar 38 in the y-direction are fixed to the housing of the image forming apparatus 1. Thus, the film unit 30-2 is supported by the image forming apparatus 1. The support bar 38 improves the bending stiffness of the film unit 30-2.

[0100] Flanges (not shown) for limiting the movement of the tubular membrane 35 in the y direction are mounted near the two ends of the support bar 38 in the y direction.

[0101] A heater thermometer 62 is disposed in the -z direction of the heater unit 40. For example, the heater thermometer 62 is a thermistor. The heater thermometer 62 is mounted and supported on the surface of the support member 36 in the -z direction. The temperature-sensing element of the heater thermometer 62 contacts the heater unit 40 through a hole penetrating the support member 36 in the z direction. The heater thermometer 62 measures the temperature of the heater unit 40.

[0102] The thermostat 68 is configured in the same manner as the heater thermometer 62. The thermostat 68 is integrated into the circuitry described later. When the measured temperature of the heater unit 40 exceeds a predetermined temperature, the thermostat 68 stops supplying power to the heating element assembly 45.

[0103] Figure 6 This is a top view (viewed from the -z direction) of the heater thermometer 62 and the thermostat 68. Figure 6 The description of the support member 36 is omitted here. Furthermore, the following description of the configuration of the heater thermometer 62, the thermostat 68, and the membrane thermometer 64 explains the configuration of each temperature sensing element.

[0104] Multiple heater thermometers 62 (center heater thermometer 62-1 and end heater thermometer 62-2) are arranged side-by-side in the y-direction. The multiple heater thermometers 62 are disposed on the heating element assembly 45. The multiple heater thermometers 62 are disposed within a range in the y-direction of the heating element assembly 45. The multiple heater thermometers 62 are disposed at the center in the x-direction of the heating element assembly 45. That is, when viewed from the z-direction, the multiple heater thermometers 62 and the heating element assembly 45 at least partially overlap.

[0105] Multiple thermostats 68 (central thermostat 68-1 and end thermostat 68-2) are configured in the same manner as the multiple heater thermometers 62 described above.

[0106] The plurality of heater thermometers 62 include a central heater thermometer 62-1 and an end heater thermometer 62-2 (thermometers disposed on one side in the long side direction).

[0107] The central heater thermometer 62-1 measures the temperature of the central heating element 45-1. The central heater thermometer 62-1 is positioned within the area of ​​the central heating element 45-1. That is, when viewed from the z-direction, the central heater thermometer 62-1 overlaps with the central heating element 45-1.

[0108] The end heater thermometer 62-2 measures the temperature of the second end heating element 45-3. As described above, the heating of the first end heating element 45-2 and the second end heating element 45-3 is controlled in the same manner. Therefore, the temperature of the first end heating element 45-2 is the same as the temperature of the second end heating element 45-3. The end heater thermometer 62-2 is positioned within the range of the second end heating element 45-3. That is, when viewed from the z-direction, the end heater thermometer 62-2 and the second end heating element 45-3 overlap.

[0109] Multiple thermostats 68 include a central thermostat 68-1 and an end thermostat 68-2.

[0110] When the temperature of the central heating element 45-1 exceeds the predetermined temperature, the central thermostat 68-1 stops supplying power to the heating element assembly 45. The central thermostat 68-1 is positioned within the area of ​​the central heating element 45-1. That is, when viewed from the z-direction, the central thermostat 68-1 and the central heating element 45-1 overlap.

[0111] When the temperature of the first end heating element 45-2 exceeds a predetermined temperature, the end thermostat 68-2 stops supplying power to the heating element assembly 45. As described above, the heating of the first end heating element 45-2 and the second end heating element 45-3 is controlled in the same manner. Therefore, the temperature of the first end heating element 45-2 is the same as the temperature of the second end heating element 45-3. The end thermostat 68-2 is positioned within the range of the first end heating element 45-2. That is, when viewed from the z-direction, the end thermostat 68-2 and the first end heating element 45-2 overlap.

[0112] As described above, a central heater thermometer 62-1 and a central thermostat 68-1 are disposed on the central heating element 45-1. This allows for the measurement of the temperature of the central heating element 45-1. Furthermore, when the temperature of the central heating element 45-1 exceeds a predetermined temperature, power to the heating element assembly 45 is stopped.

[0113] The end heater thermometer 62-2 is mounted on the second end heating element 45-3.

[0114] Therefore, the temperature of the second end heating element 45-3 is measured. Since the temperature of the first end heating element 45-2 is the same as the temperature of the second end heating element 45-3, the temperatures of the first end heating element 45-2 and the second end heating element 45-3 are measured.

[0115] An end thermostat 68-2 is mounted on the first end heating element 45-2. When the temperature of the first end heating element 45-2 and the second end heating element 45-3 exceeds a predetermined temperature, power to the heating element assembly 45 is stopped.

[0116] Multiple heater thermometers 62 and multiple thermostats 68 are arranged alternately along the y-direction. As described above, the first end heating element 45-2 is arranged in the +y direction of the central heating element 45-1. The end thermostat 68-2 is arranged within the range of the first end heating element 45-2. The central heater thermometer 62-1 is arranged closer to the +y direction than the center of the central heating element 45-1 in the y-direction. The central thermostat 68-1 is arranged closer to the -y direction than the center of the central heating element 45-1 in the y-direction. As described above, the second end heating element 45-3 is arranged in the -y direction of the central heating element 45-1. The end heater thermometer 62-2 is arranged within the range of the second end heating element 45-3. Thus, the end thermostat 68-2, the central heater thermometer 62-1, the central thermostat 68-1, and the end heater thermometer 62-2 are arranged sequentially from the +y direction to the -y direction.

[0117] Typically, the thermostat 68 connects and stops the circuit by utilizing the bending deformation of the bimetal as temperature changes. The thermostat is elongated to fit the shape of the bimetal. Furthermore, terminals extend outwards from both ends along the long side of the thermostat 68. Connectors for external wiring are crimped to these terminals. Therefore, space needs to be ensured on the outer side of the thermostat 68 along its long side. Since there is no extra space in the x-direction in the fixing device 30, the long side of the thermostat 68 is arranged along the y-direction. In this case, if multiple thermostats 68 are arranged adjacent to each other in the y-direction, it is difficult to ensure sufficient space for the connection of external wiring.

[0118] As described above, multiple heater thermometers 62 and multiple thermostats 68 are arranged alternately along the y-direction. Thus, the heater thermometers 62 are positioned near the thermostats 68 in the y-direction. This ensures sufficient space for external wiring to the thermostats 68. Furthermore, it increases the layout freedom of the thermostats 68 and heater thermometers 62 in the y-direction. Therefore, by positioning the thermostats 68 and heater thermometers 62 in optimal locations, the temperature of the fixing device 30 can be controlled. Moreover, the AC wiring connected to the multiple thermostats 68 and the DC wiring connected to the multiple heater thermometers 62 can be easily separated. This suppresses noise generation in the circuit.

[0119] like Figure 3 As shown, the membrane thermometer 64 is positioned inside the cylindrical membrane 35 and in the +x direction of the heater unit 40. The membrane thermometer 64 contacts the inner circumferential surface of the cylindrical membrane 35 to measure the temperature of the cylindrical membrane 35.

[0120] Figure 7 This is a circuit diagram of the heating device according to the first embodiment. Figure 7 middle, Figure 5 The bottom view and Figure 6 The top views are positioned above and below the paper, respectively. Furthermore, in Figure 7 In the top view below, a plurality of membrane thermometers 64 are depicted together with the cross-section of the cylindrical membrane 35. The plurality of membrane thermometers 64 include a central membrane thermometer 64-1 and an end membrane thermometer 64-2 (thermometers disposed on one side in the long side direction).

[0121] The central membrane thermometer 64-1 is in contact with the center of the cylindrical membrane 35 in the y-direction. The central membrane thermometer 64-1 is in contact with the cylindrical membrane 35 within the y-direction range of the central heating element 45-1. The central membrane thermometer 64-1 measures the temperature of the center of the cylindrical membrane 35 in the y-direction.

[0122] The end-film thermometer 64-2 contacts the end of the cylindrical membrane 35 in the -y direction. The end-film thermometer 64-2 also contacts the cylindrical membrane 35 within the y-direction range of the second end-heating element 45-3. The end-film thermometer 64-2 measures the temperature of the end of the cylindrical membrane 35 in the -y direction. As described above, the heating of the first end-heating element 45-2 and the second end-heating element 45-3 is controlled in the same manner. Therefore, the temperature of the end of the cylindrical membrane 35 in the -y direction is the same as the temperature of the end in the +y direction.

[0123] Power supply 95 is connected to central contact 52-1 via central triac switch element 96-1. Power supply 95 is connected to end contact 52-2 via end triac switch element 96-2. CPU 91 independently controls the ON / OFF states of central triac switch element 96-1 and end triac switch element 96-2. When CPU 91 turns on central triac switch element 96-1, power is supplied from power supply 95 to central heating element 45-1. This causes central heating element 45-1 to heat up. When CPU 91 turns on end triac switch element 96-2, power is supplied from power supply 95 to first end heating element 45-2 and second end heating element 45-3. This causes first end heating element 45-2 and second end heating element 45-3 to heat up. In summary, the heating of the central heating element 45-1, the first end heating element 45-2, and the second end heating element 45-3 are controlled independently. The central heating element 45-1, the first end heating element 45-2, and the second end heating element 45-3 are connected in parallel with respect to the power supply 95.

[0124] Power supply 95 is connected to common contact 58 via central thermostat 68-1 and end thermostat 68-2. Central thermostat 68-1 and end thermostat 68-2 are connected in series.

[0125] When the temperature of the central heating element 45-1 rises abnormally, the measured temperature of the central thermostat 68-1 exceeds the predetermined temperature. At this time, the central thermostat 68-1 stops supplying power from the power supply 95 to the entire heating element assembly 45.

[0126] When the temperature of the first end heating element 45-2 rises abnormally, the measured temperature of the end thermostat 68-2 exceeds a predetermined temperature. At this time, the end thermostat 68-2 stops supplying power from the power supply 95 to the entire heating element assembly 45. As described above, the heating of the first end heating element 45-2 and the second end heating element 45-3 is controlled in the same manner. Therefore, when the temperature of the second end heating element 45-3 rises abnormally, the temperature of the first end heating element 45-2 also rises accordingly. Therefore, when the temperature of the second end heating element 45-3 rises abnormally, the end thermostat 68-2 also stops supplying power from the power supply 95 to the entire heating element assembly 45.

[0127] CPU 91 (control unit 6) measures the temperature of the central heating element 45-1 via central heater thermometer 62-1. CPU 91 measures the temperature of the second end heating element 45-3 via end heater thermometer 62-2. The temperature of the second end heating element 45-3 is the same as that of the first end heating element 45-2. When the fixing unit 30 is started, CPU 91 measures the temperature of the heating element assembly 45 via heater thermometer 62. When the temperature of the heating element assembly 45 is lower than a predetermined temperature, CPU 91 causes the heating element assembly 45 to heat up for a short time. Thereafter, CPU 91 starts the rotation of the pressure roller 30-1. The viscosity of the lubricating oil coated on the inner circumferential surface of the cylindrical film 35 is reduced by the heating of the heating element assembly 45. Therefore, when the pressure roller 30-1 starts to rotate, the sliding between the heater unit 40 and the cylindrical film 35 is ensured.

[0128] CPU 91 measures the temperature of the center portion of the cylindrical film 35 in the y-direction using a central film thermometer 64-1. CPU 91 measures the temperature of the ends of the cylindrical film 35 in the -y-direction using an end film thermometer 64-2. The temperature of the ends of the cylindrical film 35 in the -y-direction is the same as the temperature of the ends of the cylindrical film 35 in the +y-direction. During operation of the fixing device 3, CPU 91 measures the temperatures of the center and ends of the cylindrical film 35 in the y-direction. CPU 91 performs phase control or wavenumber control on the power supplied to the heating element assembly 45 using a central triac switch element 96-1 and an end triac switch element 96-2. CPU 91 controls the energization of the central heating element 45-1 based on the temperature measurement results of the center portion of the cylindrical film 35 in the y-direction. CPU 91 controls the energization of the first end heating element 45-2 and the second end heating element 45-3 based on the temperature measurement results of the ends of the cylindrical film 35 in the y-direction.

[0129] At least two of the multiple heating elements (central heating element 45-1, first end heating element 45-2, and second end heating element 45-3) are heated and controlled by a CPU 91 (control unit 6). A central heater thermometer 62-1 measures the temperature of the central heating element 45-1. An end heater thermometer 62-2 measures the temperature of one of the two end heating elements (second end heating element 45-3).

[0130] Multiple heating elements have a second end heating element 45-3 disposed on one side in the long direction and a first end heating element 45-2 (another end heating element) disposed on the other side in the long direction. An end heater thermometer 62-2 and an end film thermometer 64-2 are disposed on the same side as the second end heating element 45-3. An end heater thermometer 62-2 and an end film thermometer 64-2 are not disposed on the same side as the first end heating element 45-2.

[0131] The structure of the heating device can also be the same as described above. Figure 3 The fixing device 30 shown has different structures, for example Figure 8 The structure shown.

[0132] Figure 8 This is a front sectional view of another structural example of the heating device according to the first embodiment. Figure 8 The heating device shown is a fixing device 300. The structure of the fixing device 300 is a structure in which a heat transfer component 49 is further added to the structure of the fixing device 30 described above. Hereinafter, the structure of the fixing device 300 will be described focusing on the differences from the structure of the fixing device 30 described above. In addition, for components that have the same structure as the fixing device 30 described above, the same reference numerals will sometimes be used and the description will be omitted.

[0133] The membrane unit 30-2 includes a cylindrical membrane 35, a heater unit 40, a heat transfer component 49, a support component 36, a support bar 38, a heater thermometer 62, a thermostat 68, and a membrane thermometer 64.

[0134] The heat transfer component 49 is formed of a metal material with high thermal conductivity, such as copper. The external shape of the heat transfer component 49 is the same as the external shape of the substrate 41 of the heater unit 40. The heat transfer component 49 is configured to be aligned with the surface of the heater unit 40 in the -z direction (second surface 40-2, see reference). Figure 4 )touch.

[0135] Support component 36 supports heater unit 40 across heat transfer component 49.

[0136] The heat transfer component 49 reduces the temperature gradient along the long side of the cylindrical membrane 35 and the heater unit 40, and averages the temperature distribution of the cylindrical membrane 35 and the heater unit 40. Thus, the heat transfer component 49 prevents localized temperature increases along the long side of the cylindrical membrane 35 and the heater unit 40.

[0137] A heater thermometer 62 is disposed in the -z direction of the heater unit 40, sandwiching a heat transfer element 49. For example, the heater thermometer 62 is a thermistor. The heater thermometer 62 is mounted and supported on the surface of the support member 36 in the -z direction. The temperature-sensing element of the heater thermometer 62 contacts the heat transfer element 49 through a hole penetrating the support member 36 in the z direction. The heater thermometer 62 measures the temperature of the heater unit 40 through the heat transfer element 49.

[0138] The thermostat 68 is configured in the same manner as the heater thermometer 62. The thermostat 68 is integrated into the circuitry described later. When the temperature of the heater unit 40, as measured by the heat transfer element 49, exceeds a predetermined temperature, the thermostat 68 stops supplying power to the heating element assembly 45.

[0139] The heating control of the heating apparatus (fixing apparatus 30, 300) according to the first embodiment will be described below.

[0140] Figure 9 This is an excerpted block diagram of the main components of the heating device used for heating control as described below.

[0141] Power supply 95 supplies power to heating element assembly 45.

[0142] Heating element group 45 heats cylindrical membrane 35.

[0143] Power supply 95 supplies power to motor 70. The power generated by the powered motor 70 is transmitted to drive force transmission component 71. Drive force transmission component 71 is, for example, a drive gear.

[0144] The drive force transmission component 71 converts the power transmitted from the motor 70 into a rotational force for rotating the pressure roller 30-1.

[0145] A rotational force is applied to the pressure roller 30-1 from the driving force transmission component 71, and the pressure roller 30-1 is driven to rotate clockwise at a predetermined speed, for example.

[0146] The tubular membrane 35 abuts against the pressure roller 30-1. Frictional force acts within the roll gap N formed by the contact between the tubular membrane 35 and the pressure roller 30-1, driven by the rotation of the pressure roller 30-1. Through the frictional force in the roll gap N, a rotational force caused by the driven force acts on the tubular membrane 35. For example, the pressure of the pressure plate can be set such that the contact pressure between the tubular membrane 35 and the pressure roller 30-1 is 300N to 500N under the total pressure.

[0147] The current sensor 72 measures the drive current of the motor 70. The current sensor 72 measures, for example, the drive current on the board (not shown) or control board (not shown) of the motor 70. The current sensor 72 outputs information indicating the measurement result to the control unit 6. The measurement result is, for example, the current value of the drive current of the motor 70.

[0148] The control unit 6 acquires information from the current sensor 72 representing the measurement result of the drive current of the motor 70. The control unit 6 (memory 92) may also temporarily store the acquired information.

[0149] The drive current value of motor 70 is related to the drive torque of motor 70. Therefore, control unit 6 can estimate the drive torque of motor 70 from the value based on the measured drive current value. Furthermore, the value based on the drive current includes the drive current value itself. Additionally, the value based on the drive current value can be, for example, the value of the drive torque of motor 70 converted from the drive current value.

[0150] For example, if the drive current of motor 70 is too high, it is assumed that the drive torque is too large, and it is assumed that the remaining amount of lubricant has decreased. Furthermore, for example, if the drive current of motor 70 is too low, it is assumed that the drive torque is too small, and it is assumed that poor contact has occurred between the cylindrical diaphragm 35 and the pressure roller 30-1.

[0151] When the heating element assembly 45 heats the tubular film 35, the temperature near the heating element assembly 45 rises sharply when the rotation of the tubular film 35 stops. This is, for example, because when the rotation of the tubular film 35 stops, the paper S no longer passes between the tubular film 35 and the pressure roller 30-1, and the heat is not carried away by the paper S. Additionally, the stopping of the rotation of the tubular film 35 is mainly caused by a decrease in the remaining amount of lubricant or poor contact between the tubular film 35 and the pressure roller 30-1. When the temperature near the heating element assembly 45 rises sharply, the tubular film 35 and the like may sometimes be damaged.

[0152] As described above, when the rotation of the cylindrical diaphragm 35 stops due to a decrease in the amount of lubricant remaining, the drive torque of the motor 70 becomes greater than the normal drive torque. Therefore, the current value of the drive current measured by the current sensor 72 increases compared to the normal state.

[0153] On the other hand, when the rotation of the tubular diaphragm 35 stops due to poor contact between the tubular diaphragm 35 and the pressure roller 30-1, the driving torque of the motor 70 becomes less than the normal driving torque. Therefore, compared with the normal situation, the current value of the driving current measured by the current sensor 72 becomes smaller.

[0154] The control unit 6 (memory 92) pre-stores a threshold value used to determine if the rotation of the cylindrical diaphragm 35 stops due to a decrease in the amount of lubricant remaining. This threshold value is an upper limit value representing the current value based on the drive current of the motor 70. Furthermore, in the following description, the stoppage of rotation of the cylindrical diaphragm 35 caused by a decrease in the amount of lubricant remaining is also referred to as the "first anomaly".

[0155] Furthermore, the control unit 6 (memory 92) pre-stores a threshold value used to determine if the rotation of the tubular membrane 35 stops due to poor contact between the tubular membrane 35 and the pressure roller 30-1. This threshold value is a lower limit value representing the current value based on the drive current of the motor 70. Additionally, in the following description, the rotation stop of the tubular membrane 35 caused by poor contact between the tubular membrane 35 and the pressure roller 30-1 is also referred to as a "second anomaly".

[0156] When the current value, based on the measurement result of the drive current output from the current sensor 72, is outside the predetermined range, the control unit 6 controls the power supply 95 to stop supplying power to the heating element assembly 45. This stops heating of the cylindrical diaphragm 35. Alternatively, in this situation, the control unit 6 can control the power supply 95 and further stop supplying power to the motor 70.

[0157] Furthermore, the predetermined range is the range between the upper and lower limits of the current value based on the drive current of motor 70. In the following description, a situation where the current value based on the drive current of motor 70 is not within the predetermined range is also referred to as "outside the predetermined range".

[0158] Hereinafter, an example of the operation of the fixing device 30 according to the first embodiment will be described.

[0159] Figure 10 This is a flowchart illustrating the operation of the fixing device 30 during the anomaly detection process. The anomaly detection process is used to detect the aforementioned first and second anomalies, which may cause a sharp increase in the temperature of the heating element, potentially damaging the heating device.

[0160] The control unit 6 measures whether the motor 70 is in a driving state (i.e., the state in which the fixing device 30 performs heat treatment) (ACT 001), and when the motor 70 is not in a driving state (ACT 001: No), the control unit 6 stands by until the fixing device 30 changes to the state of performing heat treatment according to an instruction from the outside.

[0161] When the motor 70 is in a driving state (ACT001: Yes), the control unit 6 acquires information from the current sensor 72 representing the measurement result of the driving current of the motor 70. The control unit 6 compares the current value based on the driving current of the motor 70 (which is based on the acquired information) with a lower limit value pre-stored in the memory 92 (ACT002).

[0162] When the value of the drive current of the motor 70 based on the acquired information is greater than or equal to the lower limit value pre-stored in the memory 92 (ACT002: No), the control unit 6 performs the processing of ACT003. The control unit 6 compares the value of the drive current of the motor 70 based on the acquired information with the upper limit value pre-stored in the memory 92 (ACT003).

[0163] When the current value based on the drive current of motor 70 (which is based on the acquired information) is less than or equal to the upper limit value pre-stored in memory 92 (ACT003: No), control unit 6 executes the process of ACT004. Control unit 6 detects whether the heating process of fixing device 30 is in the end state (ACT004).

[0164] When the heat treatment is complete (ACT004: Yes), the process ends. Figure 10 The flowchart illustrates the operation of the heating process in the fixing device 30. On the other hand, when in the state of continuing heating process (ACT004: No), the fixing device 30 returns to the process described in ACT001 above and repeats the above series of processes.

[0165] In the above-described ACT002 process, when the current value of the drive current of the motor 70 based on the acquired information is less than the lower limit value stored in the memory 92 (ACT002: Yes), the control unit 6 executes the ACT005 process. The control unit 6 determines that an abnormality (second abnormality) has occurred due to poor contact between the tubular membrane 35 and the pressure roller 30-1, causing the tubular membrane 35 to stop rotating (ACT005).

[0166] In the aforementioned ACT003 process, when the current value based on the drive current of the motor 70 (which is based on the acquired information) is greater than the upper limit value stored in the memory 92 (ACT003: Yes), the control unit 6 executes the ACT006 process. The control unit 6 determines that an abnormality (first abnormality) has occurred due to a decrease in the remaining amount of lubricant, causing the cylindrical diaphragm 35 to stop rotating (ACT006).

[0167] When a first or second abnormality is detected, the control unit 6 controls the power supply 95 to stop supplying power to the heater unit 40 (heating element assembly 45) (ACT007). This stops heating the cylindrical membrane 35. Furthermore, the control unit 6 determines that a first or second abnormality has occurred when the current value, as shown by the measurement result of the drive current of the motor 70 output from the current sensor 72, is outside a predetermined range. This predetermined range is the range from the lower limit to the upper limit of the current value based on the drive current of the motor 70 pre-stored in the memory 92.

[0168] The control unit 6 further controls the power supply 95 to stop supplying power to the motor 70. This stops the rotation of the motor 70 (ACT008). Consequently, the heating process of the fixing unit 30 is stopped (ACT009).

[0169] The control unit 6 outputs information indicating the above-mentioned abnormality (ACT010). For example, the control unit 6 controls the control panel 8 to display the information indicating the above-mentioned abnormality on the display unit (e.g., a touch panel (not shown)) of the control panel 8.

[0170] At this point, Figure 10 The operation in the heating process of the fixing device 30, as shown in the flowchart, has ended.

[0171] As described above, the fixing devices 30 and 300 (heating devices) according to the first embodiment measure the current value of the drive current of the motor 70 used to rotate the pressure roller 30-1. When the value based on the measured current value is outside a predetermined range, the fixing devices 30 and 300 determine that an abnormality has occurred and stop the heating process of the heater unit 4 on the cylindrical film 35.

[0172] By providing this structure, the fixing device 30 can prevent a sharp rise in temperature near the heater unit 4 due to the cessation or reduction in rotation speed of the tubular film 35. Therefore, the fixing devices 30 and 300 (heating devices) according to the first embodiment can prevent equipment damage caused by a sharp rise in temperature near the heater unit 40 (heating section).

[0173] Furthermore, the abnormalities mentioned here include the abnormality of the cylindrical diaphragm 35 stopping rotation, the abnormality of the cylindrical diaphragm 35 decreasing rotational speed, etc. As described above, since the current value of the drive current of the motor 70 is related to the drive torque of the motor 70, the fixing devices 30 and 300 can infer the occurrence of an abnormality based on the current value. In addition, the fixing devices 30 and 300 compare the measured current value with preset upper and lower limits. Therefore, the fixing devices 30 and 300 can detect both a first abnormality and a second abnormality: the first abnormality is based on the current value exceeding the upper limit, and the second abnormality is based on the current value falling below the lower limit.

[0174] In this embodiment, the control unit 6 is configured to stop supplying power to the heater unit 40 when the value of the drive current of the motor 70, measured by the current sensor 72, is outside a predetermined range. However, it is not limited to this configuration; for example, the control unit 6 may also be configured to stop supplying power to the heater unit 40 when the current value remains outside the predetermined range for a predetermined time. In this case, the predetermined time may be set, for example, to about 1 to 2 seconds.

[0175] With this structure, when the value of the drive current changes only momentarily for some reason, the control unit 6 does not stop the heating process of the heater unit 40 on the cylindrical membrane 35. This prevents erroneous detection of abnormalities.

[0176] Alternatively, for example, when the difference between the current value of the drive current of the motor 70 measured by the current sensor 72 and the current value under normal conditions becomes greater than a predetermined value, the control unit 6 can stop supplying power to the heater unit 40. Furthermore, in this case, the current value under normal conditions is stored, for example, in a memory 92. Additionally, in this case, for example, the average value of the current values ​​over a recent predetermined period can be set as the current value under normal conditions. This is because, generally, the current value under normal conditions is not always constant, but can gradually change. For example, as the remaining amount of lubricant gradually decreases, the load torque in the motor 7 gradually increases. Therefore, the current value under normal conditions of the drive current of the motor 70 gradually increases over time.

[0177] In addition to the aforementioned structure that stops the heating process based on the current value of the drive current of the motor 70, the fixing devices 30 and 300 may also have the following structure: The fixing devices 30 and 300 may also be equipped with a structure that stops the heat treatment even when the temperature of the cylindrical film 35 or the heater unit 40 exceeds a predetermined upper limit temperature.

[0178] (Second Implementation)

[0179] The heating apparatus (fusing apparatus 30, 300) according to the first embodiment described above is structured to stop the heating process based on the value of the current driven by the motor 7. The heating apparatus (fusing apparatus 30) according to the second embodiment described below is structured to stop the heating process when the temperature of the cylindrical film 35 exceeds a predetermined upper limit temperature. Furthermore, the heating apparatus according to the second embodiment measures the value of the current driven by the motor 70. Then, when the measured current value is outside a predetermined range, the heating apparatus changes the upper limit temperature from a first upper limit temperature to a second upper limit temperature lower than the first upper limit temperature.

[0180] The image processing apparatus according to the second embodiment is an image forming apparatus 1, and the heating device is a fixing device 30. The schematic structure and hardware structure of the image forming apparatus 1 according to the second embodiment are shown in the reference. Figures 1 to 2 The structure of the image forming apparatus 1 according to the first embodiment is the same as described, therefore the description is omitted. Furthermore, the fixing apparatus 3 according to the second embodiment is the same as the referenced one, except for the structure related to heating control. Figures 3 to 8 The structure of the fixing device 30 according to the first embodiment is the same, so the description is omitted.

[0181] Figure 11 This is a diagram illustrating an example of the temperature distribution as the paper S continuously passes through the fixing device 30 according to this embodiment. Figure 11 An example is shown of the temperature distribution along the long side of the cylindrical membrane 35 and the temperature distribution along the long side of the surface of the heater unit 40 that is not in contact with the cylindrical membrane 35. The surface that is not in contact with the cylindrical membrane 35 of the heater unit 40 is the surface on which the central heater thermometer 62-1 and the end heater thermometer 62-2 are disposed.

[0182] Figure 11 An example is shown where paper of size B5 is used as the paper S passing through. The area outside the paper-passing region of the tubular film 35 does not contact the paper S. Therefore, as... Figure 11 As shown, outside the paper-passing area in the tubular membrane 35, heat is not carried away by the paper S. Therefore, the temperature outside the paper-passing area generally tends to be higher than the temperature in the paper-passing area.

[0183] In the fixing apparatus 30 according to the second embodiment, the end heater thermometer 62-2 is disposed outside the paper passage area. When the temperature of the tubular film 35 exceeds the upper limit temperature T1, the fixing apparatus 30 stops supplying power to the heater unit 40 to prevent abnormal temperature rise caused by the heating process of the heater unit 40. The upper limit temperature is preset to a temperature within a range where the components of the fixing apparatus 30 will not be damaged by temperature rise. Furthermore, in Figure 11In the example shown, the upper limit temperature T1 is set to 250°C.

[0184] When the tubular film 35 stops rotating, the measured temperatures by the central heater thermometer 62-1 and the end heater thermometer 62-2 rise sharply. This is because, as described above, since the rotation of the tubular film 35 has stopped, the paper S no longer passes through, and heat is not carried away by the paper S. When the temperature near the heating range rises abnormally due to the heating process of the heater unit 40, components such as the film unit 30-2 and the pressure roller 30-1 may be damaged. In addition, as described above, the reason for the tubular film 35 stopping rotation may be the depletion of the lubricant inside the tubular film 35 or poor contact between the tubular film 35 and the pressure roller 30-1.

[0185] Figure 12 This is a diagram illustrating an example of temperature progression from room temperature when the tubular membrane 35 is heated by the heater unit 40 in a non-rotating state. Figure 12 The temperature shift of the cylindrical membrane 35 and the temperature shift of the end heater thermometer 62-2 are shown. The end heater thermometer 62-2 is disposed on the surface of the heater unit 40 that does not contact the cylindrical membrane 35. In this embodiment, the surface of the heater unit 40 that does not contact the cylindrical membrane 35 is the surface opposite to the heating element assembly 45. Hereinafter, the surface of the heater unit 40 that does not contact the cylindrical membrane 35 is also referred to as the "heater unit back side".

[0186] Therefore, the temperature rise of the end heater thermometer 62-2 (i.e., the temperature rise of the back side of the heater unit) is slower compared to the temperature rise of the cylindrical membrane 35. Consequently, the temperature of the cylindrical membrane 35 exceeds the upper limit temperature T1 before the temperature on the back side of the heater unit reaches it. Therefore, in a structure where heating is stopped when the temperature of the end heater thermometer 62-2 reaches the upper limit temperature T1, there is a possibility of component damage. Therefore, it is necessary to stop the heating process before the temperature of the end heater thermometer 62-2 reaches the upper limit temperature T1.

[0187] When the drive current of the motor 70 is outside the predetermined range, the fixing device 30 according to the second embodiment changes the preset upper limit temperature (upper limit temperature T1) to a lower upper limit temperature (upper limit temperature T2). When the drive current of the motor 70 is outside the predetermined range, as described above, it is assumed that the cylindrical film 35 is in a stopped rotating state. When the cylindrical film 35 stops rotating, the temperature of the cylindrical film 35 may rise sharply. Therefore, the fixing device 30 can stop the heating process of the heater unit 4 before component damage by changing the upper limit temperature to a lower temperature as described above.

[0188] The heating control of the heating device (fixing device 30) according to the second embodiment will be described in detail below.

[0189] Figure 13 This is an excerpted block diagram of the main components of the heating device used for heating control as described below.

[0190] Power supply 95 supplies power to heating element assembly 45.

[0191] Heating element group 45 heats cylindrical membrane 35.

[0192] Power supply 95 supplies power to motor 70. The power generated by the powered motor 70 is transmitted to drive force transmission component 71. Drive force transmission component 71 is, for example, a drive gear.

[0193] The drive force transmission component 71 converts the power transmitted from the motor 70 into a rotational force for rotating the pressure roller 30-1, thereby causing the pressure roller 30-1 to rotate.

[0194] A rotational force is applied to the pressure roller 30-1 from the driving force transmission component 71, and the pressure roller 30-1 is driven to rotate clockwise at a predetermined speed, for example.

[0195] The tubular membrane 35 abuts against the pressure roller 30-1. Frictional force acts within the roll gap N formed by the contact between the tubular membrane 35 and the pressure roller 30-1 as the pressure roller 30-1 rotates. The rotational force acts on the tubular membrane 35 through the frictional force in the roll gap N. For example, the pressure of the pressure plate can be set such that the contact pressure between the tubular membrane 35 and the pressure roller 30-1 is 300N to 500N under the total pressure.

[0196] The current sensor 72 measures the drive current of the motor 70. The current sensor 72 measures, for example, the drive current on the motor 70's substrate (not shown) or control substrate (not shown). The current sensor 72 outputs information indicating the measurement result to the control unit 6. The measurement result is, for example, the value of the drive current.

[0197] The control unit 6-1 acquires information from the current sensor 72 representing the measurement result of the drive current in the motor 70. The control unit 6-1 (memory 92) can temporarily store the acquired information.

[0198] The value of the drive current of motor 70 is related to the drive torque of motor 70. Therefore, control unit 6-1 can estimate the drive torque of motor 70 based on the value of the drive current.

[0199] When the heating element assembly 45 heats the tubular film 35, the temperature near the heating element assembly 45 rises sharply when the rotation of the tubular film 35 stops. This is because when the rotation of the tubular film 35 stops, the paper S no longer passes between the tubular film 35 and the pressure roller 30-1, and the heat is not carried away by the paper S. Furthermore, the stopping of the rotation of the tubular film 35 is mainly caused by a decrease in the remaining amount of lubricant or poor contact between the tubular film 35 and the pressure roller 30-1. When the temperature near the heating element assembly 45 rises sharply, the tubular film 35 and other components may sometimes be damaged.

[0200] When the rotation of the cylindrical diaphragm 35 stops due to the decrease in the amount of lubricant remaining, the driving torque of the motor 70 becomes greater than the normal driving torque. As a result, the driving current value measured by the current sensor 72 increases compared to the normal state.

[0201] On the other hand, when the rotation of the tubular diaphragm 35 stops due to poor contact between the tubular diaphragm 35 and the pressure roller 30-1, the driving torque of the motor 70 becomes less than the normal driving torque. Therefore, compared with the normal situation, the current value of the driving current measured by the current sensor 72 becomes smaller.

[0202] The membrane thermometer 64 contacts the inner circumferential surface of the cylindrical membrane 35 to measure the temperature of the cylindrical membrane 35. The membrane thermometer 64 outputs information indicating the measurement result to the control unit 6-1.

[0203] The control unit 6-1 acquires information indicating the temperature of the cylindrical membrane 35 output from the membrane thermometer 64. The control unit 6-1 (memory 92) can temporarily store the acquired information.

[0204] The control unit 6-1 (memory 92) stores an upper limit temperature set to prevent abnormal heating in the heater unit 40. For example, the upper limit temperature T1 is preset to the upper limit temperature under normal conditions. The control unit 6-1 compares the temperature of the cylindrical membrane 35 measured by the membrane thermometer 64 with the upper limit temperature. When the temperature of the cylindrical membrane 35 exceeds the upper limit temperature, the control unit 6-1 controls the power supply 95 to stop supplying power to the heating element assembly 45. Thus, heating of the cylindrical membrane 35 is stopped. Furthermore, in this case, the control unit 6-1 can further control the power supply 95 to stop supplying power to the motor 70.

[0205] The control unit 6-1 (memory 92) pre-stores a threshold value (an upper limit value based on the current value of the drive current) which is used to determine if the rotation of the tubular membrane 35 stops due to a decrease in the amount of lubricant remaining (a first abnormality). Furthermore, the control unit 6 (memory 92) pre-stores a threshold value (a lower limit value based on the current value of the drive current) which is used to determine if the rotation of the tubular membrane 35 stops due to poor contact between the tubular membrane 35 and the pressure roller 30-1 (a second abnormality).

[0206] When the current value, based on the measurement result of the drive current output from the current sensor 72, is outside the predetermined range, the control unit 6-1 changes the aforementioned upper limit temperature from the upper limit temperature T1, which is the upper limit temperature under normal conditions, to the upper limit temperature T2, which is the upper limit temperature under abnormal conditions. Figure 12 As shown, the upper limit temperature T2 is set to, for example, approximately 100°C. For example, as... Figure 12 As shown, the upper limit temperature T2 is set to be at least lower than the temperature at the back of the heater unit at the time point when the temperature of the cylindrical membrane 35 reaches the upper limit temperature T1 (in Figure 12 (Approximately 120℃). The time when the temperature of the cylindrical membrane 35 reaches the upper limit temperature T1 is the time when the component may be damaged.

[0207] Hereinafter, an example of the operation of the fixing device 30 according to the second embodiment will be described.

[0208] Figure 14 This is a flowchart illustrating the operation of the fixing device in the anomaly detection process. The anomaly detection process is used to detect a first anomaly and a second anomaly, which may cause a sharp rise in the temperature of the heating element, potentially damaging the heating device.

[0209] The control unit 6-1 detects whether the motor 70 is in a driving state (i.e., the state in which the fixing device 30 performs heating processing) (ACT101). When the motor 70 is not in a driving state (ACT001: No), the control unit 6-1 stands by until the fixing device 30 changes to the state of performing heating processing according to an external instruction.

[0210] When the motor 70 is in a driving state (ACT101: Yes), the control unit 6-1 acquires information from the current sensor 72 representing the measurement result of the driving current of the motor 70. The control unit 6-1 compares the current value based on the driving current of the motor 70 (which is based on the acquired information) with the lower limit value pre-stored in the memory 92 (ACT102).

[0211] When the current value based on the drive current of motor 70 (based on the acquired information) is above the lower limit of the drive current value pre-stored in memory 92 (ACT102: No), control unit 6-1 performs the processing of ACT103. Control unit 6 compares the current value based on the drive current of motor 70 (based on the acquired information) with the upper limit value pre-stored in memory 92 (ACT103).

[0212] When the current value based on the drive current of the motor 70 (which is based on the acquired information) is below the upper limit value pre-stored in the memory 92 (ACT103: No), the control unit 6-1 acquires the information representing the temperature of the cylindrical membrane 35 output from the membrane thermometer 64.

[0213] When the temperature of the cylindrical membrane 35 based on the acquired information is below the upper limit temperature T1 pre-stored in the memory 92 (ACT104: No), the control unit 6-1 detects whether the heating process has ended (ACT105). If the heating process has ended (ACT105: Yes), the control unit 6-1 detects whether the heating process has ended (ACT105: Yes). Figure 14 The operation in the heating process of the fixing device 30 shown in the flowchart ends. If the heating process continues (ACT105: No), the fixing device 30 returns to the process of ACT101 mentioned above and repeats the above series of processes.

[0214] In the above-described ACT102 process, if the current value based on the drive current of the motor 70 (which is based on the acquired information) is less than the lower limit value pre-stored in the memory 92 (ACT102: Yes), the control unit 6-1 executes the ACT006 process. The control unit 6-1 determines that an abnormality (first abnormality) has occurred due to poor contact between the tubular membrane 35 and the pressure roller 30-1, causing the rotation of the tubular membrane 35 to stop (ACT106).

[0215] In the above-described ACT103 process, when the current value based on the drive current (which is based on the acquired information) is greater than the lower limit of the current value based on the drive current pre-stored in the memory 92 (ACT103: Yes), the control unit 6-1 executes the ACT107 process. The control unit 6-1 determines that an abnormality (second abnormality) has occurred due to the reduction of the remaining amount of lubricant, causing the rotation of the cylindrical film 35 to stop (ACT107).

[0216] When a first or second anomaly is detected, the control unit 6-1 changes the upper limit temperature setting from the preset normal upper limit temperature T1 to the anomaly upper limit temperature T2 (ACT108). As described above, the upper limit temperature T2 is a temperature lower than the upper limit temperature T1.

[0217] The control unit 6-1 acquires information representing the temperature of the cylindrical membrane 35 output from the membrane thermometer 64.

[0218] When the temperature of the cylindrical membrane 35 based on the acquired information is below the upper limit temperature T2 (ACT109: No), the control unit 6-1 detects whether the heat treatment has ended (ACT105). When the heat treatment has ended (ACT105: Yes). Figure 14The operation in the heating process of the fixing device 30 shown in the flowchart ends. When the heating process continues (ACT105: No), the fixing device 30 returns to the process of ACT101 above and repeats the above series of processes.

[0219] In the aforementioned ACT104 process, when the temperature of the cylindrical membrane 35 based on the acquired information is higher than the upper limit temperature T1 pre-stored in the memory 92 (ACT104: No), the control unit 6-1 executes the ACT110 process. The control unit 6-1 controls the power supply 95 to stop supplying power to the heater unit 40 (ACT110). Therefore, heating of the cylindrical membrane 35 is stopped. Furthermore, the control unit 6-1 determines that a first or second abnormality has occurred, namely, the current value represented by the measurement result of the drive current of the motor 70 output from the current sensor 72 is outside a predetermined range. The predetermined range referred to here is, as previously described, the range from the lower limit to the upper limit of the current value based on the drive current of the motor 70 pre-stored in the memory 92.

[0220] The control unit 6-1 further controls the power supply 95 to stop supplying power to the motor 70. Therefore, the rotation operation of the motor 70 is stopped (ACT111). This, in turn, stops the heating operation of the fixing unit 30 (ACT112).

[0221] The control unit 6-1 outputs information indicating the above-mentioned abnormality (ACT113). For example, the control unit 6-1 controls the control panel 8 to display the information indicating the above-mentioned abnormality on the display unit (e.g., a touch panel (not shown)) of the control panel 8.

[0222] At this point, Figure 14 The operation in the heating process of the fixing device 30, as shown in the flowchart, has ended.

[0223] Furthermore, in the aforementioned ACT104 process, when the temperature of the cylindrical membrane 35 based on the acquired information is higher than the upper limit temperature T1 pre-stored in the memory 92 (ACT104: No), the control unit 6-1 executes the ACT110 process. The control unit 6-1 controls the power supply 95 to stop supplying power to the heater unit 40 (ACT110). This stops heating the cylindrical membrane 35.

[0224] The control unit 6-1 further controls the power supply 95 to stop supplying power to the motor 70. Therefore, the rotation operation of the motor 70 is stopped (ACT111). This, in turn, stops the heating operation of the fixing unit 30 (ACT112).

[0225] The control unit 6-1 outputs information indicating the determined abnormality (ACT113). For example, the control unit 6-1 controls the control panel 8 and outputs information indicating that the temperature of the cylindrical membrane 35 exceeds the normal upper limit temperature T1 to the display unit (e.g., a touch panel (not shown)) of the control panel 8.

[0226] At this point, Figure 14 The operation in the heating process of the fixing device 30, as shown in the flowchart, has ended.

[0227] As described above, the fixing apparatus 30 (heating device) according to the second embodiment measures the temperature of the cylindrical film 35. The fixing apparatus 30 compares the measured temperature of the cylindrical film 35 with an upper limit temperature. When the temperature of the cylindrical film 35 exceeds the upper limit temperature, the fixing apparatus 30 stops the heating process of the heating unit 40 on the cylindrical film 35.

[0228] Furthermore, the fixing unit 30 measures the current value of the drive current of the motor 7 used to rotate the pressure roller 30-1. When the measured current value is outside a predetermined range, the fixing units 30 and 300 determine that an abnormality has occurred and change the upper limit temperature from the normal upper limit temperature T1 to the abnormal upper limit temperature T2. The upper limit temperature T2 is a temperature lower than the upper limit temperature T1.

[0229] By including this structure, the fixing device 30 according to the second embodiment can prevent a sharp rise in temperature near the heater unit 40 due to the cessation of rotation or a decrease in rotation speed of the tubular film 35. Therefore, the fixing device 30 according to the second embodiment can prevent equipment damage caused by a sharp rise in temperature near the heater unit 40 (heating section).

[0230] Furthermore, in the second embodiment, the control unit 6-1 is configured to change the upper limit temperature from the upper limit temperature T1 to the upper limit temperature T2 in either the case where a first abnormality is determined to have occurred or the case where a second abnormality is determined to have occurred. However, it is not limited to this configuration. For example, it is also possible that when a first abnormality is determined to have occurred, the control unit 6-1 changes the upper limit temperature T1 to the upper limit temperature T2, and when a second abnormality is determined to have occurred, the control unit 6-1 changes the upper limit temperature T1 to the upper limit temperature T3.

[0231] In this case, it is preferable to set the upper limit temperature T2 lower than the upper limit temperature T3. This is because it is assumed that when the first anomaly occurs, the temperature of the heater unit 40 rises more rapidly than when the second anomaly occurs. The first anomaly is, as described above, the anomaly that causes the rotation of the tubular film 35 to stop due to poor contact between the tubular film 35 and the pressure roller 30-1. The second anomaly is, as described above, the anomaly that causes the rotation of the tubular film 35 to stop due to reduced slippage caused by a decrease in the amount of lubricant remaining.

[0232] Furthermore, in the second embodiment, the control unit 6-1 is configured to stop supplying power to the heater unit 40 when the temperature measured by the membrane thermometer 64 exceeds the upper limit temperature. However, it is not limited to this configuration. For example, the control unit 6-1 may be configured to stop supplying power to the heater unit 40 when the rate of temperature rise measured by the membrane thermometer 64 exceeds a predetermined rate of rise (threshold). In this case, for example, when the value of the current based on the drive current is outside a predetermined range, the control unit 6-1 may change the value of the predetermined rate of rise (threshold) to a lower value.

[0233] Furthermore, in the first and second embodiments, the heating element assembly 45 has a structure comprising three heating elements (a central heating element 45-1, a first end heating element 45-2, and a second end heating element 45-3). However, the number of heating elements included in the heating element assembly 45 may be one or two, or it may be four or more.

[0234] Furthermore, in the first and second embodiments, the plurality of heater thermometers 62 is a structure comprising two heater thermometers (a central heater thermometer 62-1 and an end heater thermometer 62-2). However, the number of heater thermometers 62 may be three or more.

[0235] Furthermore, in the first and second embodiments, the plurality of thermostats 68 is a structure comprising two thermostats (a central thermostat 68-1 and an end thermostat 68-2). However, the number of the plurality of thermostats 68 may be three or more.

[0236] In addition, the heating element included in the heating element group 45 may be a heating element with positive resistance temperature characteristics.

[0237] Furthermore, the image processing apparatus according to the first and second embodiments can also be a decolorizing apparatus. In this case, the heating device is a decolorizing section. The decolorizing apparatus performs a process to decolorize (eliminate) the image formed on paper by a decolorizing toner. The decolorizing section decolorizes the decolorizing toner image formed on the paper passing through the roll gap N by heating.

[0238] Furthermore, some or all of the functions of the image forming apparatus 1 can be implemented using hardware such as ASIC (Application Specific Integrated Circuit), PLD (Programmable Logic Device), and FPGA (Field Programmable Gate Array). The program can be recorded on a computer-readable recording medium. Such media include portable media such as floppy disks, magneto-optical disks, ROMs, and CD-ROMs, as well as storage devices such as hard disks built into computer systems. The program can be transmitted via telecommunication lines.

[0239] In the first and second embodiments, the control unit 6-1 is a software functional unit, but it can also be a hardware functional unit such as an LSI.

[0240] According to the above embodiments, the heating device includes an annular fixing belt, a pressure roller, a heating unit, a driving unit, a current measuring unit, and a control unit. For example, the heating device is the fixing device 30 or 300 according to the embodiments, the annular fixing belt is the tubular film 35 according to the embodiments, the pressure roller is the pressure roller 30-1 according to the embodiments, the heating unit is the heater unit 40 according to the embodiments, the driving unit is the motor 70 according to the embodiments, the current measuring unit is the current sensor 72 according to the embodiments, and the control unit is the control unit 6 or 6-1 according to the embodiments.

[0241] The annular fixing belt is supported for rotatable movement. A pressure roller abuts against the outer side of the fixing belt. A heating unit heats the fixing belt. A drive unit rotates the pressure roller to cause the fixing belt to rotate. A current measuring unit measures the drive current in the drive unit. A control unit stops heating based on the measurement result of the drive current measured by the current measuring unit. For example, the measurement result of the drive current is based on the current value of the drive current according to the embodiment.

[0242] Furthermore, when the value of the current based on the drive current is outside the predetermined range, the control unit can stop the heating of the heating unit.

[0243] Furthermore, if the value of the current based on the drive current remains outside the predetermined range for more than a predetermined time, the control unit may stop the heating of the heating unit.

[0244] Furthermore, the heating device may also include a temperature measuring unit for measuring the temperature of the heating element. Additionally, when the current value based on the drive current is outside a predetermined range, the control unit may stop heating the heating element based on the temperature measured by the temperature sensing unit.

[0245] Furthermore, when the current value based on the drive current is outside a predetermined range, the control unit can change the upper limit temperature of the heating unit from a predetermined first upper limit temperature to a second upper limit temperature lower than the first upper limit temperature. In this case, when the temperature measured by the temperature detection unit exceeds the upper limit temperature, the control unit can stop the heating of the heating unit.

[0246] While several embodiments have been described, these embodiments are provided by way of example only and are not intended to limit the scope of the invention. These embodiments can be implemented in various other ways and can be omitted, substituted, or modified in various ways without departing from the spirit of the invention. These embodiments and their variations are included within the scope and spirit of the invention, and are similarly included within the scope of the invention as described in the claims and its equivalents.

Claims

1. A heating device, characterized in that, include: The annular fixing belt is supported so that it can rotate and move. The pressure roller abuts against the outer side of the fixing belt; The heating unit heats the fixing belt; The drive unit rotates the fixing belt by rotating the pressure roller; A current measuring unit measures the drive current in the drive unit; The control unit stops the heating unit from heating based on the measurement result of the drive current measured by the current measuring unit. as well as The temperature measuring unit measures the temperature of the heating element. When the value of the current based on the driving current is outside a predetermined range, the control unit changes the upper limit temperature setting of the heating unit from a predetermined first upper limit temperature to a second upper limit temperature lower than the first upper limit temperature. When the temperature measured by the temperature measuring unit exceeds the second upper limit temperature, the heating unit stops heating.

2. The heating device according to claim 1, characterized in that, When the value of the current based on the driving current remains outside a predetermined range for more than a predetermined time, the control unit causes the heating unit to stop heating.

3. A heating control method, characterized in that, The pressure roller, which abuts against the outside of the annular fixing belt, is rotated by a drive unit, causing the fixing belt to rotate passively. The fixing belt is supported so that it can rotate freely. The fixing belt is heated by a heating element. Based on the measurement results of the drive current in the drive unit, the heating unit is stopped from heating. When the value of the current based on the driving current is outside a predetermined range, the upper limit temperature setting of the heating element is changed from a predetermined first upper limit temperature to a second upper limit temperature lower than the first upper limit temperature. When the temperature of the heating element, as measured by the temperature measuring unit, exceeds the second upper limit temperature, the heating element stops heating.

4. The heating control method according to claim 3, characterized in that, When the value of the current based on the driving current remains outside a predetermined range for more than a predetermined time, the heating element stops heating.

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