Image forming device and heating control method

Abstract

An image forming device and a heating control method are provided, which can safely perform image fixing processing. The image forming device of the embodiment has a fixing unit and a control unit. The fixing unit has a heating unit and a fixing belt. The fixing belt contacts the heating unit and a component not in contact with the heating unit, respectively, and is heated by the heating unit. The control unit determines whether the fixing belt is connected to a ground wire, and stops the heating processing of the heating unit when it is determined that the fixing belt is not connected to the ground wire.

Description

Technical Field

[0001] Embodiments of the present invention relate to an image forming apparatus and a heating control method. Background Art

[0002] In a belt-type (on-demand) fuser, static electricity may accumulate on the fuser belt depending on the sliding properties of components such as paper and heaters and the fuser belt. If static electricity accumulates on the fuser belt, it may cause static electricity offset, and the quality of the output image will be reduced. In this regard, a method of discharging the accumulated static electricity by connecting the fuser belt to the ground (reference potential) (hereinafter referred to as "GND") is considered. However, in this case, there is a problem that the connection between the fuser belt, which is a rotating object, and GND is easily unstable. Summary of the invention

[0003] An object of the present invention is to provide an image forming apparatus and a heating control method capable of suppressing degradation of image quality.

[0004] The image forming apparatus of the embodiment includes a fixing unit and a control unit. The fixing unit includes a heating unit and a fixing belt. The fixing belt contacts the heating unit and a component not in contact with the heating unit, respectively, and is heated by the heating unit. The control unit determines whether the fixing belt is connected to a ground wire, and stops the heating process of the heating unit when it is determined that the fixing belt is not connected to the ground wire. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1 It is an external view showing an example of the overall configuration of the image forming apparatus according to the embodiment.

[0006] Figure 2 This is a block diagram showing the hardware configuration of the image forming apparatus according to the embodiment.

[0007] Figure 3 It is a diagram showing a specific structure of a fixing device according to an embodiment.

[0008] Figure 4 It is a diagram showing a specific structure of the heater according to the embodiment.

[0009] Figure 5 1 is a schematic diagram showing a mechanism for detecting whether or not the fixing belt according to the embodiment is connected to GND.

[0010] Figure 6 1 is a schematic diagram showing a mechanism for detecting whether or not the fixing belt according to the embodiment is connected to GND.

[0011] Figure 7 This is a flowchart showing the operation of the image forming apparatus 1 according to the embodiment.

[0012] Figure 8This is a flowchart showing the operation of the image forming apparatus 1 according to the embodiment.

[0013] Description of Reference Numerals

[0014] 1…image forming device; 2…system bus; 10…image reading unit; 20…control panel; 30…image forming unit; 31…transfer belt; 32…exposure unit; 33…developer; 34…photosensitive drum; 35…transfer unit; 35a…support roller; 40…sheet storage unit; 41…sheet; 50…fixer; 51…heating roller; 52…pressure roller; 53…fixer belt; 54…fixer pad; 55…heater; 56…fixer support; 58…thermistor; 61a…conveying roller; 61b…conveying roller; 62a…paper discharge roller; 62b…paper discharge roller; 70…control device; 71…processor; 80…conveying unit; 120…auxiliary storage device; 130…network interface; 501…photocoupler; 501a…light emitting diode; 501b…light receiving element; 502…microcomputer DETAILED DESCRIPTION

[0015] Hereinafter, an image forming apparatus and a heating control method according to an embodiment will be described with reference to the drawings.

[0016] Hereinafter, an overall configuration example of the image forming apparatus will be described.

[0017] Figure 1 1 is an appearance diagram showing an example of the overall structure of an image forming apparatus according to an embodiment. The image forming apparatus 1 according to the embodiment is a multifunction peripheral (MFP). The image forming apparatus 1 performs an image forming process and an image fixing process. The image forming process is a process of forming an image on a sheet. The image fixing process is a process of fixing the image formed on the sheet. The sheet is, for example, an original, paper with text, images, etc. recorded thereon, etc. The sheet may be any object as long as it is an object that can be read by the image forming apparatus 1. The image forming apparatus 1 reads the image displayed on the sheet and generates digital data, thereby generating an image file.

[0018] The image forming apparatus 1 includes an image reading section 10 , a control panel 20 , an image forming section 30 , a sheet storage section 40 , a fixing device 50 , conveying rollers 61 a and 61 b ​​, paper discharge rollers 62 a and 62 b , and a control device 70 .

[0019] The image reading unit 10 reads the image of the object to be read as light and dark. For example, the image reading unit 10 reads an image printed on a sheet of the object to be read set on the manuscript reading table. The image reading unit 10 records the read image data. The recorded image data can be sent to other information processing devices via a network. The recorded image data can also be formed into an image on a sheet by the image forming unit 30.

[0020] The control panel 20 includes a display unit and an operating unit. The display unit is a display device such as a liquid crystal display and an organic EL (ElectroLuminescence) display. The display unit displays various information about the image forming device 1 under the control of the control device 70. The operating unit includes a plurality of buttons, etc. The operating unit accepts user operations. The operating unit outputs a signal corresponding to the operation performed by the user to the control device 70. It should be noted that the display unit and the operating unit can also be configured as an integrated touch panel.

[0021] The image forming section 30 performs an image forming process. In the image forming process, the image forming section 30 forms an image on a sheet based on image data generated by the image reading section 10 or image data received via a communication path.

[0022] The image forming unit 30 includes a transfer belt 31 , an exposure unit 32 , a plurality of developers 33 (developers 33Y, 33M, 33C, and 33K), a plurality of photosensitive drums 34 (photosensitive drums 34Y, 34M, 34C, and 34K), and a transfer unit 35 .

[0023] The transfer belt 31 is an intermediate transfer body and rotates in the direction indicated by the arrow (counterclockwise direction) by the rotation of the roller.

[0024] The exposure unit 32 is provided at a position opposite to the photosensitive drums 34Y, 34M, 34C, and 34K of the respective developers 33Y, 33M, 33C, and 33K. The exposure unit 32 irradiates the surface (photosensitive layer) of each photosensitive drum 34Y, 34M, 34C, and 34K with laser. The exposure unit 32 is controlled to emit light based on the image data by the control of the control device 70. The exposure unit 32 irradiates the laser based on the image data. As a result, the negative charge on the surface (photosensitive layer) of each photosensitive drum 34Y, 34M, 34C, and 34K disappears. As a result, an electrostatic pattern is formed on the surface (photosensitive layer) of the photosensitive drum 34Y, 34M, 34C, and 34K at the position irradiated with the laser. That is, an electrostatic latent image is formed on the surface (photosensitive layer) of the photosensitive drum 34Y, 34M, 34C, and 34K by the laser irradiation of the exposure unit 32. It should be noted that the exposure unit 32 may use LED (Light Emitting Diode) light instead of laser light.

[0025] The developers 33Y, 33M, 33C, and 33K supply toner to the photosensitive drums 34Y, 34M, 34C, and 34K. For example, the developer 33Y develops the electrostatic latent image on the surface (photosensitive layer) of the photosensitive drum 34Y with the yellow (Y) toner. In addition, the developer 33M develops the electrostatic latent image on the surface (photosensitive layer) of the photosensitive drum 34M with the magenta (M) toner. In addition, the developer 33C develops the electrostatic latent image on the surface (photosensitive layer) of the photosensitive drum 34C with the cyan (C) toner. In addition, the developer 33K develops the electrostatic latent image on the surface (photosensitive layer) of the photosensitive drum 34K with the black (K) toner.

[0026] The developers 33Y, 33M, 33C, and 33K form toner images as visible images on the photosensitive drums 34Y, 34M, 34C, and 34K. The toner images formed on the photosensitive drums 34Y, 34M, 34C, and 34K are transferred (primary transfer) onto the transfer belt 31 .

[0027] The transfer section 35 includes a support roller 35a and a secondary transfer roller 35b. The transfer section 35 transfers the toner image on the transfer belt 31 to the sheet at the secondary transfer position U. The secondary transfer position U is a position where the support roller 35a and the secondary transfer roller 35b face each other across the transfer belt 31. The transfer section 35 provides a transfer bias controlled by a transfer current to the transfer belt 31. The transfer section 35 transfers the toner image on the transfer belt 31 to the sheet by the transfer bias. The control device 70 controls the transfer current used for the secondary transfer process.

[0028] The sheet storage unit 40 includes one or more paper feed cassettes. The paper feed cassettes store sheets 41 of a predetermined size and a predetermined type. The paper feed cassettes include a pickup roller. The pickup roller takes out sheets 41 one by one from the paper feed cassette. The pickup roller feeds the taken-out sheets 41 to the conveying unit 80 .

[0029] The fixing device 50 performs an image fixing process. Specifically, the fixing device 50 fixes the toner image on the sheet 41 by heating and pressing the sheet 41. It should be noted that the structure of the heating process of the fixing device 50 will be described in detail later.

[0030] The conveying rollers 61a and 61b supply the sheet 41 supplied from the paper supply cassette to the image forming unit 30. The conveying rollers 61a and 61b are provided at opposing positions.

[0031] The paper discharge rollers 62a and 62b discharge the sheet 41 on which the image is formed by the fixing device 50 to the discharge portion. The paper discharge rollers 62a and 62b are provided at opposing positions.

[0032] The control device 70 controls each functional unit of the image forming apparatus 1 .

[0033] The conveying unit 80 conveys the sheet 41. The conveying unit 80 includes a conveying path and a plurality of rollers (not shown). The conveying path is a path for conveying the sheet 41. The rollers rotate under the control of the control device 70 to convey the sheet 41.

[0034] An example of the hardware configuration of the image forming apparatus 1 will be described below.

[0035] Figure 2 FIG. 1 is a block diagram showing the hardware configuration of the image forming apparatus 1. Figure 2 , only the characteristic hardware configuration of the image forming apparatus 1 in this embodiment is shown.

[0036] The image forming apparatus 1 includes an image reading unit 10, a control panel 20, an image forming unit 30, a sheet storage unit 40, a control device 70, an auxiliary storage device 120, and a network interface 130. The functional units are connected via a system bus 2 so as to be able to communicate data with each other.

[0037] The image reading unit 10 , the control panel 20 , the image forming unit 30 , and the sheet storage unit 40 are the same as those described above, and thus their description is omitted. Next, the fixing device 50 , the control device 70 , the auxiliary storage device 120 , and the network interface 130 are described.

[0038] The fixing device 50 includes an optical coupler 501 and a microcomputer 502 (microcomputer). It should be noted that the optical coupler 501 and the microcomputer 502 will be described later. It should be noted that the microcomputer 502 may also be a component of the control device 70. Alternatively, the microcomputer 502 may also be a device integrated with the processor 71.

[0039] The control device 70 includes a processor 71, a ROM (Read Only Memory) 72, and a RAM (Random Access Memory) 73. The processor 71 is a processor such as a CPU (Central Processing Unit). The processor 71 executes various processes by developing and executing a program stored in the ROM 72 in the RAM 73.

[0040] The ROM 72 stores a program for operating the processor 71. The RAM 73 temporarily stores data used by each functional unit of the image forming apparatus 1. It should be noted that the RAM 73 may also store digital data generated by the image reading unit 10. The RAM 73 may temporarily store jobs and job logs.

[0041] The auxiliary storage device 120 is, for example, a hard disk or an SSD (Solid State Drive), and stores various data, such as digital data, jobs, and job logs.

[0042] The network interface 130 sends and receives data to and from other devices. Here, other devices are information processing devices such as personal computers, tablet terminals, and smartphones. The network interface 130 acts as an input interface to receive data or instructions sent from other devices. The instructions sent from other devices are printing execution instructions. In addition, the network interface 130 acts as an output interface to send data to other devices.

[0043] Hereinafter, an example of the structure of the fixing device 50 will be described.

[0044] Figure 3 It is a front cross-sectional view of the fixing device 50. The fixing device 50 includes a pressure roller 530p and a film unit 530h.

[0045] The pressure roller 530p and the film unit 530h form a nip N. The pressure roller 530p presses the toner image on the sheet entering the nip N. The pressure roller 530p rotates and conveys the sheet. The pressure roller 530p includes a core 532, an elastic layer 533, and a release layer (not shown).

[0046] In this way, the pressure roller 530p can press the surface of the cylindrical film 535 and can be rotationally driven.

[0047] The core bar 532 is formed into a cylindrical shape by a metal material such as stainless steel. Both ends of the core bar 532 in the axial direction are supported so as to be rotatable. The core bar 532 is driven to rotate by a motor (not shown). The core bar 532 abuts against a cam member (not shown). The cam member rotates to move the core bar 532 toward and away from the film unit 530h.

[0048] The elastic layer 533 is made of an elastic material such as silicone rubber, and is formed on the outer peripheral surface of the core metal 532 with a certain thickness.

[0049] The mold release layer (not shown) is formed of a resin material such as PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer) and is formed on the outer peripheral surface of the elastic layer 533 .

[0050] The hardness of the outer peripheral surface of the pressure roller 530p is preferably 40° to 70° as measured by an ASKER-C hardness meter under a load of 9.8 N. Thus, the area of ​​the nip N and the durability of the pressure roller 530p are ensured.

[0051] The pressure roller 530p can approach and move away from the film unit 530h by the rotation of the cam member. When the pressure roller 530p is brought close to the film unit 530h and pressed by the pressure spring, a roller gap N is formed. On the other hand, when a sheet is jammed in the fixing device 50, the sheet can be removed by moving the pressure roller 530p away from the film unit 530h. In addition, when the cylindrical film 535 stops rotating, such as during sleep, the plastic deformation of the cylindrical film 535 is prevented by moving the pressure roller 530p away from the film unit 530h.

[0052] The pressure roller 530p is driven by a motor to rotate. When the pressure roller 530p rotates with the nip N formed, the cylindrical film 535 of the film unit 530h rotates accordingly. The pressure roller 530p rotates with the sheet disposed in the nip N, thereby conveying the sheet in the conveying direction W.

[0053] The film unit 530 h heats the toner image on the sheet entering the nip N. The film unit 530 h includes a cylindrical film 535 , a heater 55 , a heat transfer member 549 , a support member 536 , a support column 538 , a heater thermometer 562 , a thermostat 568 , and a thermistor 58 .

[0054] The cylindrical film 535 is formed into a cylindrical shape. The cylindrical film 535 has a base layer, an elastic layer and a release layer in order from the inner peripheral side. The base layer is formed into a cylindrical shape by a material such as nickel (Ni). The elastic layer is stacked on the outer peripheral surface of the base layer. The elastic layer is formed by an elastic material such as silicone rubber. The release layer is stacked on the outer peripheral surface of the elastic layer. The release layer is formed by a material such as PFA resin.

[0055] The heater 55 includes a substrate and a heating layer. In the present application, the x direction, the y direction, and the z direction are defined as follows. The y direction is the long side direction of the substrate. The y direction is parallel to the width direction of the tubular film 535. The x direction is the short side direction of the substrate, and the z direction is the normal direction of the substrate. The detailed structure of the heater 55 will be described later.

[0056] like Figure 3 As shown, a straight line CL is defined connecting the center pc of the pressure roller 530p and the center hc of the film unit 530h. The center 541c of the substrate in the x direction is arranged in the +x direction of the straight line CL. Thus, since the substrate extends in the +x direction of the roller gap N, the sheet passing through the roller gap N is easily peeled off from the film unit 530h.

[0057] The center 545c of the heat generating layer in the x direction is arranged on the straight line CL. The heat generating layer is entirely contained in the region of the nip N and is arranged at the center of the nip N. Thus, the heat distribution in the nip N becomes uniform, and the sheet passing through the nip N is uniformly heated.

[0058] like Figure 3As shown, the heater 55 is arranged inside the cylindrical film 535. A lubricant (not shown) is applied to the inner peripheral surface of the cylindrical film 535. The heater 55 contacts the inner peripheral surface of the cylindrical film 535 via the lubricant. When the heater 55 generates heat, the viscosity of the lubricant decreases. Thus, the sliding property between the heater 55 and the cylindrical film 535 is ensured.

[0059] As described above, the tubular film 535 is a belt-shaped film that slides on the surface of the heater 55 while being in contact with the heater 55 on one side.

[0060] The heat transfer member 549 is formed of a metal material having high thermal conductivity such as copper. The outer shape of the heat transfer member 549 is the same as the outer shape of the substrate of the heater 55. The heat transfer member 549 is arranged in contact with the surface of the heater 55 in the -z direction.

[0061] The support member 536 is formed of a resin material such as a liquid crystal polymer. The support member 536 is arranged so as to cover both sides of the heater 55 in the -z direction and the x direction. The support member 536 supports the heater 55 via the heat transfer member 549. Round chamfers are formed at both ends of the support member 536 in the x direction. The support member 536 supports the inner circumferential surface of the cylindrical film 535 at both ends of the heater 55 in the x direction.

[0062] When the sheet passing through the fixing device 50 is heated, a temperature distribution is generated in the heater 55 according to the size of the sheet. If the heater 55 locally becomes hot, its temperature may exceed the heat resistance temperature of the support member 536 formed of a resin material. The heat transfer member 549 is used to average the temperature distribution of the heater 55. Thus, the heat resistance of the support member 536 is ensured.

[0063] Figure 3 The support 538 shown is formed of a steel plate material or the like. The cross section of the support 538 perpendicular to the y direction is formed into a U-shape. The support 538 is mounted in the -z direction of the support member 536 so that the opening of the U-shape is blocked by the support member 536. The support 538 extends in the y direction. Both ends of the support 538 in the y direction are fixed to the housing of the image forming device 1. Thus, the film unit 530h is supported by the image forming device 1. The support 538 increases the bending rigidity of the film unit 530h. Flanges (not shown) for limiting the movement of the cylindrical film 535 in the y direction are mounted near both ends of the support 538 in the y direction.

[0064] The heater thermometer 562 is arranged in the -z direction of the heater 55 via the heat transfer member 549. For example, the heater thermometer 562 is a thermistor. The heater thermometer 562 is mounted and supported on the -z direction surface of the support member 536. The temperature sensing element of the heater thermometer 562 passes through the hole that penetrates the support member 536 in the z direction and contacts the heat transfer member 549. The heater thermometer 562 measures the temperature of the heater 55 via the heat transfer member 549.

[0065] The thermostat 568 is arranged similarly to the heater thermometer 562. When the temperature of the heater 55 detected via the heat transfer member 549 exceeds a predetermined temperature, the thermostat 568 cuts off the energization to the heat generating layer.

[0066] like Figure 3 As shown, the thermistor 58 (thin film thermometer) is arranged inside the cylindrical film 535. The thermistor 58 is in contact with the inner peripheral surface of the cylindrical film 535, and measures the temperature of the cylindrical film 535.

[0067] It should be noted that the image forming apparatus 1 may also include an ambient thermometer (not shown) in addition to the heater thermometer 562 and the thermistor 58 (film thermometer). The ambient thermometer measures the temperature around the installation location. The ambient thermometer may be installed at any location near the fuser 50. The vicinity of the fuser 50 refers to a location where the ambient thermometer can measure the temperature (ambient temperature) of the space where the fuser 50 is located. The ambient thermometer may also be installed, for example, in a housing located outside the film unit 530h.

[0068] Figure 4 It is a diagram showing a specific structure of the heater 55 .

[0069] like Figure 4 As shown, the heater 55 is composed of four layers including a glass layer, a heat generating layer, a glass layer, and a substrate in order from the surface on the side in contact with the fixing belt 53 .

[0070] The substrate is formed of a metal material such as stainless steel or a ceramic material such as aluminum nitride. The substrate is formed in an elongated rectangular plate shape. The substrate is arranged on the inner side of the cylindrical film 535 in the radial direction. The substrate has the axial direction of the cylindrical film 535 as the long side direction.

[0071] The heat generating layer is formed of, for example, a silver-palladium alloy, etc. The heat generating layer is formed in a rectangular shape with the y direction as the long side direction and the x direction as the short side direction.

[0072] Hereinafter, an example of a mechanism provided in the fixing device 50 of the image forming apparatus 1 for detecting whether the fixing belt 53 is connected to the GND will be described.

[0073] Figure 51 is a schematic diagram showing a mechanism for detecting whether the fixing belt 53 (specifically, the cylindrical film 535 ) of the present embodiment is connected to GND.

[0074] like Figure 5 As shown in FIG. 1 , as a mechanism for detecting whether the fixing belt 53 is connected to GND, a photocoupler 501 and a microcomputer 502 are used. It should be noted that other insulating elements such as a current transformer may be used instead of the photocoupler 501. That is, as long as the current flowing on the primary circuit side can be detected on the secondary circuit side in a non-contact manner, it is not limited to Figure 5 The composition of the mechanism shown.

[0075] like Figure 5 As shown, the optical coupler 501 includes a light emitting diode 501a and a light receiving element 501b. The anode side of the light emitting diode 501a is connected to the power supply on the primary circuit side. In addition, the cathode side of the light emitting diode 501a is connected to the fixing belt 53. In addition, the fixing belt 53 is connected to GND. The anode side of the light receiving element 501b is connected to the power supply on the secondary circuit side. In addition, the cathode side of the light receiving element 501b is connected to the microcomputer 502 and GND.

[0076] According to the above configuration, when the fixing belt 53 is connected to GND, the current from the power supply on the primary circuit side flows, so the light emitting diode 501a emits light. And when the light receiving element 501b receives the light emitted by the light emitting diode 501a, the current from the power supply on the secondary circuit side is energized. When the microcomputer 502 detects that the power is on, it outputs a notification indicating that it is normal to the control device 70.

[0077] The control device 70 obtains the notification output from the microcomputer 502. When the control device 70 obtains the notification indicating normality, it determines that the fixing belt 53 is connected to GND. When the control device 70 determines that the fixing belt 53 is connected to GND, it starts rotating the fixing belt 53 (or keeps rotating) and starts heating processing (or keeps heating processing) with the heater 55.

[0078] On the other hand, when the fixing belt 53 is not connected to GND, Figure 6 As shown. Figure 6 As shown, for example, when the connection between the fixing belt 53 and GND is cut off due to a circuit break, the current from the power supply on the primary circuit side does not flow. Therefore, the light-emitting diode 501a does not emit light. Furthermore, if the light-receiving element 501b no longer receives light from the light-emitting diode 501a, the current from the power supply on the secondary circuit side is stopped. If the microcomputer 502 detects that the power is not supplied, a notification indicating an abnormality is output to the control device 70.

[0079] The control device 70 obtains the notification output from the microcomputer 502. When the control device 70 obtains the notification indicating the abnormality, it determines that the fixing belt 53 is not connected to the GND. When the control device 70 determines that the fixing belt 53 is not connected to the GND, it stops the rotation of the fixing belt 53 (or does not start the rotation) and stops the heating process of the heater 55 (or does not start the heating process).

[0080] According to the above configuration, it is possible to reliably detect whether the fixing belt 53 is connected to GND, and when the fixing belt 53 is not connected to GND, the operation of the fixing belt 53 and the heater 55 can be reliably stopped. It should be noted that in the present embodiment, the microcomputer 502 is configured to output a notification indicating an abnormality when the power is not supplied, but the present invention is not limited thereto. For example, the microcomputer 502 may also output a notification indicating an abnormality when the magnitude of the current is less than a predetermined value.

[0081] Hereinafter, an example of the operation of the above-mentioned mechanism for detecting whether or not the fixing belt 53 is connected to GND will be described.

[0082] Figure 7 This is a flowchart showing the operation of the image forming apparatus 1 according to the present embodiment.

[0083] The microcomputer 502 detects the power-on state (ACT001). If the microcomputer 502 detects that the power is on, it outputs a notification indicating normality to the control device 70. On the other hand, if the microcomputer 502 detects that the power is not on, it outputs a notification indicating abnormality to the control device 70. The control device 70 obtains the notification output from the microcomputer 502.

[0084] When the control device 70 receives a notification indicating an abnormality, it determines that the fixing belt is not connected to GND. When the control device 70 determines that the fixing belt 53 is not connected to GND (ACT002 "No"), it stops the rotation of the fixing belt 53 and the heating process of the heater 55 (that is, does not start the operation) (ACT003). Figure 7 The operation of the image forming apparatus 1 shown in the flowchart is completed.

[0085] On the other hand, when the control device 70 determines that the fixing belt 53 is connected to GND (YES in ACT002 ), the control device 70 starts the rotation of the fixing belt 53 and the heating process of the heater 55 (ACT004 ).

[0086] After that, when a predetermined time (for example, one second) has passed (ACT005 "Yes"), microcomputer 502 detects the power-on state again (ACT006). If microcomputer 502 detects that the power is not on, it outputs a notification indicating an abnormality to control device 70. Control device 70 obtains the notification output from microcomputer 502.

[0087] When the control device 70 receives the notification indicating the abnormality, it determines that the fixing belt 53 is not connected to GND. When the control device 70 determines that the fixing belt 53 is not connected to GND (ACT007 "No"), it stops the rotation of the fixing belt 53 and the heating process of the heater 55 (ACT003). Figure 7 The operation of the image forming apparatus 1 shown in the flowchart is completed.

[0088] On the other hand, if the microcomputer 502 detects that power is on, a notification indicating normal operation is output to the control device 70. The control device 70 obtains the notification output from the microcomputer 502. When the control device 70 obtains the notification indicating normal operation, it determines that the fixing belt 53 is connected to GND. When the control device 70 determines that the fixing belt 53 is connected to GND (ACT007 "Yes"), it continues to rotate the fixing belt 53 and the heating process of the heater 55. Thereafter, when a predetermined time (for example, one second) has passed (ACT005 "Yes"), the microcomputer 502 detects the power-on state again (ACT006). The subsequent actions are the same as above.

[0089] (Variation Example)

[0090] For example, the fixing belt 53 may become a charged portion due to a failure of the heater 55 or damage to the glass layer. When the fixing belt 53 becomes a charged portion and the connection between the fixing belt 53 and GND is disconnected, a current from the power supply on the primary circuit side is applied to the fixing belt 53. In this case, the light emitting diode 501a of the photocoupler 501 may emit light by mistake.

[0091] When the light emitting diode 501a emits light by mistake, the light receiving element 501b receives the light emitted by the light emitting diode 501a and energizes the current from the power supply on the secondary circuit side. If the microcomputer 502 detects that the power is on, it outputs a notification indicating that it is normal to the control device 70. If the control device 70 receives the notification indicating that it is normal, it mistakenly determines that the fixing belt 53 is connected to GND. Therefore, although the fixing belt 53 is not connected to GND, it is possible to perform the rotation action of the fixing belt 53 and the heating process of the heater 55.

[0092] In the following, it is assumed that the heater 55 is a heater that performs a heating process while repeatedly switching between an on state and an off state. In this case, in order to prevent malfunctions such as those described above, for example, the microcomputer 502 may detect the power-on state only when the state of the heating process of the heater 55 is the off state.

[0093] Next, another example of the operation of the above-mentioned mechanism for detecting whether or not the fixing belt 53 is connected to GND will be described.

[0094] Figure 8 1 is a flowchart showing the operation of the image forming apparatus 1 according to the present embodiment. Figure 8 The actions of ACT101 to ACT104 shown are similar to Figure 7 The operations of ACT001 to ACT004 shown are the same, so the description is omitted.

[0095] After the operation of ACT 104, when a predetermined time (for example, one second) has passed (ACT 105 "Yes"), the microcomputer 502 (or the control device 70) detects the state of the heating process of the heater 55 (ACT 106). When the state of the heating process of the heater 55 is the on state (ACT 107 "No"), the microcomputer 502 does not detect the power-on state.

[0096] When the heating process of the heater 55 is off (ACT 107: Yes), the microcomputer 502 detects the power-on state again (ACT 108). If the microcomputer 502 detects that the power is not on, it outputs a notification indicating an abnormality to the control device 70. The control device 70 receives the notification output from the microcomputer 502.

[0097] When the control device 70 receives the notification indicating the abnormality, it determines that the fixing belt 53 is not connected to GND. When the control device 70 determines that the fixing belt 53 is not connected to GND (ACT109 “No”), the rotation of the fixing belt 53 and the heating operation of the heater 55 are stopped (ACT103). Figure 8 The operation of the image forming apparatus 1 shown in the flowchart is completed.

[0098] On the other hand, if the microcomputer 502 detects that power is on, it outputs a notification indicating normality to the control device 70. The control device 70 obtains the notification output from the microcomputer 502. When the control device 70 obtains the notification indicating normality, it determines that the fixing belt 53 is connected to GND. When the control device 70 determines that the fixing belt 53 is connected to GND (ACT109 "Yes"), it continues to rotate the fixing belt 53 and the heating process of the heater 55. Thereafter, when a predetermined time (for example, one second) has passed (ACT105 "Yes"), the microcomputer 502 detects the state of the heating process of the heater 55 again (ACT106). The subsequent actions are the same as above.

[0099] As described above, the image forming apparatus 1 according to the above embodiment includes a fixing device 50 (fixing unit) and a control device 70 (control unit). The fixing device 50 includes a heater 55 (heating unit) and a fixing belt 53. The fixing belt 53 is in contact with the heater 55 and a component (such as a thermistor 58) that is not in contact with the heater 55. The fixing belt 53 is heated by the heater 55. The control device 70 (control unit) determines whether the fixing belt 53 is connected to GND (ground). When the control device 70 (control unit) determines that the fixing belt 53 is not connected to the ground, the heating process of the heater 55 is stopped.

[0100] By having the above configuration, the image forming apparatus 1 can detect whether the fixing belt 53 is connected to GND. Thus, when the fixing belt 53 is not connected to GND, the image forming apparatus 1 can stop the heat generation of the heater 55.

[0101] As described above, in a belt-type (on-demand) fuser, static electricity may be accumulated on the fuser belt depending on the sliding properties of components such as paper and a heater and the fuser belt. If static electricity is accumulated on the fuser belt, static electricity offset may occur, and the quality of the output image may be reduced. In response to this, the image forming device 1 can discharge static electricity by connecting the fuser belt 53 to GND. In addition, when the image forming device 1 detects that the fuser belt 53 is not connected to GND, it can stop the fuser 50, thereby preventing static electricity from accumulating in the fuser belt 53. Thus, the occurrence of static electricity offset is suppressed.

[0102] As described above, according to the image forming apparatus 1 of at least one embodiment described above, since the occurrence of electrostatic offset can be suppressed, the quality of the output image can be suppressed from being deteriorated.

[0103] When the image forming apparatus 1 detects that the fixing belt 53 is not connected to GND, the image forming apparatus 1 stops energizing the heater 55. Thus, according to at least one embodiment of the image forming apparatus 1 described above, the creeping distance between the heater 55 and the fixing belt 53 can be ensured.

[0104] The functions of the image forming device 1 in the above-mentioned embodiment can also be realized by a computer. In this case, the program for realizing the function can also be recorded in a computer-readable recording medium, so that the computer system reads and executes the program recorded in the recording medium. It should be noted that the "computer system" mentioned here includes hardware such as OS (Operating System) and peripheral devices. In addition, "computer-readable recording medium" refers to removable media such as floppy disks, optical magnetic disks, ROMs, CD-ROMs, and storage devices such as hard disks built into the computer system. Furthermore, "computer-readable recording medium" can also include a medium that dynamically maintains the program in a short period of time, such as a communication line when the program is sent via a network such as the Internet, a communication line such as a telephone line, and a medium that maintains the program for a certain period of time, such as a volatile memory inside a computer system that serves as a server or client at this time. In addition, the above-mentioned program can also be a program for realizing a part of the above-mentioned function, or a program that can realize the above-mentioned function by combining with a program already recorded in the computer system.

[0105] Although several embodiments of the present invention have been described, these embodiments are only presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other ways, and various omissions, substitutions, and changes can be made without departing from the scope of the purpose of the invention. These embodiments and their variations are included in the scope and purpose of the invention, and are also included in the invention described in the claims and their equivalents.

Claims

1. An image forming device, characterized in that: have: a fixing unit including a heating unit and a fixing belt, wherein the fixing belt is in contact with the heating unit and a member not in contact with the heating unit, respectively, and is heated by the heating unit; and The control unit determines whether the fixing belt is connected to the ground wire, and stops the heating process of the heating unit when it is determined that the fixing belt is not connected to the ground wire. The heating unit alternately switches between an operating state and a non-operating state and heats the fixing belt, wherein the operating state is a state in which a heating process is performed, and the non-operating state is a state in which a heating process is not performed, The control unit determines whether the fixing belt is connected to the ground line when the heating unit is in the non-operating state.

2. The image forming apparatus according to claim 1, wherein: The image forming apparatus further comprises: an insulating element configured to energize the insulating element when the fixing belt is connected to the ground wire, and not energize the insulating element when the fixing belt is not connected to the ground wire. The control section determines whether the fixing belt is connected to the ground line based on a current-carrying state of the insulating element.

3. The image forming apparatus according to claim 2, wherein: The insulating element is an optocoupler.

4. The image forming apparatus according to claim 3, wherein: The cathode side of the light emitting diode of the optical coupler is connected to the fixing belt, the anode side of the light emitting diode is connected to the first power supply of the heating unit, and the light receiving element of the optical coupler is connected to the second power supply, wherein the second power supply is insulated from the heating unit. The control section determines whether the fixing belt is connected to the ground line based on a power-on state of the second power source that changes according to a light-emitting state of the light-emitting diode.

5. A heating control method, characterized in that: have: A step of determining whether the fixing belt is connected to the ground wire when the heating part is in a non-working state, wherein the fixing belt is in contact with the heating part and a part not in contact with the heating part, respectively, and is heated by the heating part, and the heating part alternately switches between a working state and a non-working state and heats the fixing belt, the working state is a state in which a heating process is performed, and the non-working state is a state in which a heating process is not performed; and The step of stopping the heating process of the heating section when it is determined that the fixing belt is not connected to the ground line.

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