JP2022175173A - Fixing device and image forming apparatus - Google Patents

Abstract

To provide a fixing device that can quickly detect a rotation failure of a fixing rotating body with a simple configuration.SOLUTION: A fixing device comprises: a first failure state detection unit that, during warm-up, detects if a fixing rotating body is in a rotation failure state based on information on an increase in surface temperature of the fixing rotating body; and a control unit that, when the fixing rotating body is detected to be in the rotation failure state, controls a heat source and a motor to execute stop operations to stop heating of the fixing rotating body and rotation of a pressure rotating body.SELECTED DRAWING: Figure 9

Description

The present invention relates to a fixing device and an image forming apparatus, and more particularly to a fixing device and an image forming apparatus which have a fixing rotator and a pressure rotator and thermally fix a toner image formed on a recording medium.

An example of a conventional fixing device is disclosed in Japanese Unexamined Patent Application Publication No. 2002-200512. The fixing device disclosed in Patent Document 1 includes a fixing belt (fixing rotating body), a pressure roller (pressing rotating body), a fixing member that is in pressure contact with the pressure roller via the fixing belt to form a nip portion, and a fixing member. A pipe-shaped metal member that is fixed so as to face the inner peripheral surface of the belt and heats the fixing belt, a first temperature detection means that detects the surface temperature of the fixing belt on the upstream side of the nip portion, and a downstream side of the nip portion. and second temperature detection means for detecting the surface temperature of the pressurizing rotating body. Heating by the heating means is stopped when the temperature difference between the detected temperatures of the two temperature detecting means detected at the same timing exceeds a predetermined threshold value.

Japanese Patent Application Laid-Open No. 2011-186001

The technique of Patent Document 1 requires a temperature sensor for detecting the temperature of the pressurizing rotator in addition to the temperature sensor for detecting the temperature of the fixing rotator, which is costly.

SUMMARY OF THE INVENTION Therefore, a primary object of the present invention is to provide a novel fixing device and image forming apparatus.

Another object of the present invention is to provide a fixing device and an image forming apparatus which can detect, with a simple structure, that the fixing rotator is in a faulty rotation state as soon as possible.

A first invention is a fixing device for thermally fixing a toner image formed on a recording medium, comprising: a fixing rotary body; a heat source for heating the fixing rotary body; A pressurizing rotator that forms a nip portion between itself and the fixing rotator and rotates the fixing rotator, a motor that drives the pressurizing rotator to rotate, a temperature detector that detects the surface temperature of the fixing rotator, and a fixing rotator. During warm-up, in which the body is rotated and heated to a target temperature, it is detected whether or not the fixing rotor is in a faulty rotation state based on the temperature rise information of the surface temperature of the fixing rotor detected by the temperature detection unit. and when the first failure state detection unit detects that the fixing rotator is in a defective rotation state, the heat source and the motor are controlled to heat the fixing rotator and pressurize the rotator. The fixing device includes a control unit that executes a stop operation to stop the rotation of the fixing device.

According to the first invention, it is determined whether or not the fixing rotator is in a malfunctioning state of rotation based on the information on the temperature rise of the surface temperature of the fixing rotator. can be quickly detected. Therefore, it is possible to appropriately prevent damage due to abnormal temperature rise of the fixing rotating body.

A second invention is according to the first invention, wherein after executing the stopping operation, the control unit executes a retry operation for restarting the heating of the fixing rotator and the rotation of the pressure rotator to stop the operation and retry. After the operation is continuously performed a predetermined number of times, when the first failure state detection section detects that the fixing rotating body is in a rotation failure state, an error notification is executed and the start of the fixing device is stopped.

A third invention is according to the second invention, and includes a contact pressure changing mechanism capable of changing a contact pressure of the pressure rotating body with respect to the fixing rotating body, and before executing the retry operation, the contact pressure changing mechanism and the motor are controlled to set the contact pressure of the pressurizing rotator against the fixing rotator to a low contact pressure, and the pressurizing rotator is rotated for a predetermined period of time. A low contact pressure rotation operation for rotating is executed.

A fourth invention is according to the third invention, and when the low contact pressure rotating operation is performed, the fixing rotating body is rotated based on the temperature drop information of the surface temperature of the fixing rotating body detected by the temperature detecting section. A second faulty state detector for detecting whether or not the fixing rotor is in a faulty rotation state is provided, and the controller turns off the heat source and the motor when the second faulty state detector detects that the fixing rotator is in a faulty rotation state. A heating rotation operation is performed to rotate the pressure rotating body for a predetermined time while heating the fixing rotating body.

A fifth invention is according to any one of the first to fourth inventions, and includes a threshold storage unit for storing a plurality of rising speed threshold values set according to a value of a voltage supplied to the fixing device, and a voltage supply voltage to the fixing device. A supply voltage detector for detecting a voltage is provided, and the first failure condition detector detects that the rate of temperature increase detected by the temperature detector exceeds a rate of increase threshold selected based on the supply voltage detected by the supply voltage detector. In the above case, it is detected that the fixing rotator is in a faulty rotation state.

A sixth invention is according to any one of the first to fifth inventions, and is configured to store the accumulated number of times that the fixing rotator is detected to be in a defective rotation state by the first defective state detection section. , and a display section capable of displaying the number of accumulated times.

A seventh invention is an image forming apparatus comprising the fixing device according to any one of the first to sixth inventions.

According to this aspect of the invention, it is determined whether or not the fixing rotator is in a faulty rotation state based on information on the surface temperature of the fixing rotator. can be detected. Therefore, for example, it is possible to appropriately prevent damage due to abnormal temperature rise of the fixing rotator.

The above object, other objects, features and advantages of the present invention will become more apparent from the detailed description of embodiments given below with reference to the drawings.

1 is a schematic cross-sectional view showing the internal structure of an image forming apparatus according to a first embodiment of the invention; FIG. 2 is a schematic cross-sectional view showing a fixing device; FIG. 3 is a plan view showing a pressure roller included in the fixing device; FIG. 3 is a perspective view showing a pressure unit included in the fixing device; FIG. It is a schematic front view showing a pressurizing unit. FIG. 4 is a front view showing a contact/separation cam included in the pressurizing unit; 2 is a block diagram showing an example of the electrical configuration of the image forming apparatus; FIG. 8 is a diagram showing an example of a memory map of a RAM shown in FIG. 7; FIG. FIG. 8 is a flowchart showing an example of warm-up processing executed by the CPU shown in FIG. 7; FIG. 9 is a flowchart showing an example of warm-up processing executed by the CPU of the image forming apparatus according to the second embodiment of the present invention; FIG. 11 is a flowchart showing an example of warm-up processing executed by the CPU of the image forming apparatus according to the third embodiment of the present invention;

[First embodiment]
Referring to FIG. 1, an image forming apparatus 10 according to the first embodiment of the present invention is an apparatus for forming multicolor or monochromatic images on paper by electrophotography. As will be described later in detail, the image forming apparatus 10 includes a fixing device 46 that thermally fixes a toner image formed on a sheet (recording medium).

First, the basic configuration of the image forming apparatus 10 will be schematically described. In this specification, the surface facing the standing position of the user, that is, the surface on which the operation unit 106 (see FIG. 7) is provided is defined as the front surface (the front surface). direction). Further, the left-right direction (horizontal direction) of the image forming apparatus 10 and its constituent members is defined based on the state of viewing the image forming apparatus 10 from the user.

As shown in FIG. 1, in this first embodiment, the image forming apparatus 10 is a multifunction peripheral (MFP) having a copying function, a printer function, a scanner function, a facsimile function, and the like. The image forming apparatus 10 includes an apparatus body 12 having an image forming section 30 and the like, and an image reading device 14 arranged thereabove.

The image reading device 14 includes a document table 16 made of a transparent material. A document holding cover 18 is attached above the document table 16 via a hinge or the like so as to be freely opened and closed. The document holding cover 18 is provided with an ADF (automatic document feeder) 24 for automatically feeding the documents placed on the document placement tray 20 one by one to the image reading position 22 . Further, on the front side of the document table 16, an operation unit 106 is provided for receiving an input operation such as a print instruction by the user. The operation unit 106 is appropriately provided with a display such as a touch panel display and various operation buttons.

The image reader 14 also incorporates an image reader 26 including a light source, a plurality of mirrors, an imaging lens, a line sensor, and the like. The image reading unit 26 exposes the surface of the document with a light source, and guides the reflected light reflected from the surface of the document to the imaging lens with a plurality of mirrors. Then, the image forming lens forms an image of the reflected light on the light receiving element of the line sensor. The line sensor detects the luminance and chromaticity of the reflected light imaged on the light receiving element, and generates image data based on the image of the surface of the document. A CCD (Charge Coupled Device), CIS (Contact Image Sensor), or the like is used as the line sensor.

The apparatus main body 12 incorporates a control section 28 including a CPU 100, a RAM 102, an HDD 104 and the like (see FIG. 7), an image forming section 30, and the like. The control unit 28 (specifically, the CPU 100 ) transmits control signals to each part of the image forming apparatus 10 including the fixing device 46 in response to the user's input operation to the operation unit 106 , and the image forming apparatus 10 . Cause various actions to be performed.

The image forming section 30 includes an exposure unit 32, a developing device 34, a photosensitive drum 36, a cleaner unit 38, a charging device 40, an intermediate transfer belt unit 42, a secondary transfer roller 44, a fixing device 46, and the like. Alternatively, an image is formed on the paper conveyed from the manual paper feed tray 50 and the paper on which the image has been formed is discharged to the paper discharge tray 52 . As image data for forming an image on paper, image data read by the image reading unit 26, image data transmitted from an external computer, or the like is used.

The image data handled by the image forming apparatus 10 corresponds to four color images of black (K), cyan (C), magenta (M) and yellow (Y). For this reason, four developing devices 34, photosensitive drums 36, cleaner units 38, and charging devices 40 are provided so as to form four types of latent images corresponding to each color, thereby forming four image stations. Configured.

The photoreceptor drum 36 is an image carrier in which a photosensitive layer is formed on the surface of a conductive cylindrical substrate, and the charger 40 is a member that charges the surface of the photoreceptor drum 36 to a predetermined potential. be. The exposure unit 32 is configured as a laser scanning unit (LSU) having a laser emitting section, a reflecting mirror, and the like, and exposes the surface of the charged photoreceptor drum 36 to an electrostatic latent image corresponding to the image data. An image is formed on the surface of the photoreceptor drum 36 . The developing device 34 visualizes the electrostatic latent image formed on the surface of the photosensitive drum 36 with toner of four colors (YMCK). Also, the cleaner unit 38 removes toner remaining on the surface of the photosensitive drum 36 after development and image transfer.

The intermediate transfer belt unit 42 includes an intermediate transfer belt 54 , a drive roller 56 , a driven roller 58 , four intermediate transfer rollers 60 , etc., and is arranged above the photosensitive drum 36 . The intermediate transfer belt 54 is a flexible endless belt, stretched by a plurality of rollers such as a driving roller 56 and a driven roller 58, and its surface (outer peripheral surface) is aligned with the surface of the photosensitive drum 36. is arranged to abut on the The intermediate transfer belt 54 rotates (rotates) in a predetermined direction as the driving roller 56 rotates. The intermediate transfer rollers 60 are arranged at respective positions facing the respective photosensitive drums 36 with the intermediate transfer belt 54 interposed therebetween. At the time of image formation, the intermediate transfer roller 60 is used to sequentially transfer the toner images of the respective colors formed on the photoreceptor drums 36 onto the intermediate transfer belt 54 so as to transfer multicolor toner onto the intermediate transfer belt 54 . An image is formed.

The secondary transfer roller 44 is provided so as to face the driving roller 56 with the intermediate transfer belt 54 interposed therebetween. The toner image formed on the intermediate transfer belt 54 is transferred onto the sheet by passing the sheet through the secondary transfer nip portion between the secondary transfer roller 44 and the intermediate transfer belt 54 .

The fixing device 46 includes a fixing belt 62, a pressure roller 64, and the like, and is arranged above the secondary transfer roller 44 (on the downstream side in the paper transport direction). A fixing pad 76 and a heat source 82 (see FIG. 2) are provided inside the fixing belt 62, and the fixing belt 62 is heated by the heat source 82 to a predetermined fixing temperature (for example, 170.degree. C.). Further, the pressure roller 64 is provided so as to press the fixing belt 62 against the fixing pad 76 . As the paper passes through the fixing nip portion N (see FIG. 2) between the pressure roller 64 and the fixing belt 62, the toner image transferred to the paper is melted, mixed, and pressed against the paper. The toner image is thermally fixed. A specific configuration of the fixing device 46 will be described later.

In the apparatus main body 12, there is provided a feed tray 48 or a manual feed tray 50 for sending the paper to the discharge tray 52 via the registration roller 68, the secondary transfer roller 44 and the fixing device 46. 1 paper transport path L1 is formed. Also, when performing double-sided printing on a sheet of paper, after single-sided printing has been completed and the sheet has passed through the fixing device 46, the sheet is transferred to the first sheet conveying path L1 on the upstream side of the secondary transfer roller 44 in the sheet conveying direction. A second paper transport path L2 for returning is formed. A plurality of transport rollers 66 are appropriately provided in the first paper transport path L1 and the second paper transport path L2 for providing auxiliary driving force to the paper.

Next, the mechanical configuration of the fixing device 46 will be described with reference to FIGS. 2 to 6. FIG. The fixing device 46 includes a fixing belt 62, which is an example of a fixing rotating member, and a pressure roller 64, which is an example of a pressing rotating member. , to fix the toner image on the paper.

Specifically, as shown in FIG. 2, the fixing device 46 includes a heater unit 70 having a fixing belt 62 and the like, and a pressure unit 72 having a pressure roller 64 and the like. Each member of the heater unit 70 and the pressure unit 72 is integrally held in a predetermined arrangement by a fixing frame (not shown).

The heater unit 70 includes a fixing belt 62 that is formed in a substantially cylindrical shape and extends in the front-rear direction (the width direction of the paper). As the fixing belt 62, for example, a band-shaped base material formed of a synthetic resin such as polyimide or a metal such as nickel and provided with a release layer on the surface thereof is used. Such a fixing belt 62 is provided rotatably around its axis, and its inner diameter is, for example, 30 mm. A fixing pad 76 , a support member 78 , a reflector 80 , a heat source 82 and the like are provided inside the fixing belt 62 .

The fixing pad 76 is a fixing member that is fixedly provided so as to be in sliding contact with the inner peripheral surface of the fixing belt 62 , and is formed in the shape of a long plate extending along the axial direction of the fixing belt 62 . The fixing pad 76 has a sliding contact sheet 76a on its outer peripheral surface (at least the sliding contact surface with the fixing belt 62). Sliding oil is applied. The length of the fixing pad 76 is the same as the axial length (width) of the fixing belt 62 .

The support member 78 is a member that supports the fixing pad 76 while pressing it against the inner circumferential surface of the fixing belt 62, and both ends of the support member 78 are fixed to the fixing frame. In this first embodiment, the support member 78 is formed to have a substantially L-shaped cross section, and includes a long plate-shaped fixing portion 78a to which the fixing pad 76 is fixed, and a fixing portion 78a extending from the widthwise end of the fixing portion 78a. and a long plate-shaped standing portion 78b. A thin reflector 80 is attached to the support member 78 so as to cover the surface on the heat source 82 side.

The heat source 82 is a member for heating the fixing belt 62 and is provided so as to extend along the axial direction of the fixing belt 62 . A lamp heater such as a halogen lamp is used as the heat source 82 . In this first embodiment, the heat source 82 includes a first lamp heater 82a that heats the central portion of the fixing belt 62 in the axial direction, and a second lamp heater 82b that heats both ends of the fixing belt 62 in the axial direction. The first lamp heater 82a and the second lamp heater 82b are selectively used according to the paper width.

The pressure unit 72 includes a pressure roller 64 arranged at a position facing the fixing pad 76 with the fixing belt 62 interposed therebetween. The pressure roller 64 is provided so as to extend parallel to the axial direction of the fixing belt 62 , and presses the fixing belt 62 against the fixing pad 76 to form a fixing nip portion N between itself and the fixing belt 62 . do.

Specifically, as shown in FIG. 3 , the pressure roller 64 has a cylindrical roller portion 84 . The roller portion 84 is formed of a cylindrical core material made of metal such as aluminum and an elastic material such as silicone rubber, and is composed of an elastic layer covering the surface of the core material and a material having a low coefficient of friction such as fluorine-based resin. and a release layer covering the surface of the elastic layer. The axial length of the roller portion 84 is the same as the axial length of the fixing belt 62 .

Further, in the first embodiment, both ends of the roller portion 84 are provided with thin grip portions 86 made of a material having a large frictional resistance (that is, having a gripping force) such as silicone rubber. The grip portion 86 is arranged at a position on the outside in the width direction of the paper passing through the fixing nip portion N (outside the width of the paper), and its thickness (protruding height from the release layer) is, for example, 200 μm. By providing such a grip portion 86 on the roller portion 84, the rotational force of the pressure roller 64 is applied to the fixing belt 62 even when the pressure roller 64 is in a low contact pressure state as in the second embodiment described later. can be properly communicated.

A first motor 90 (see FIG. 7) is connected to one end (rear end) of the roller shaft 88 of the pressure roller 64 via a gear or gear train (not shown). The pressure roller 64 is driven to rotate by receiving the driving force from the first motor 90 , and as the pressure roller 64 is driven to rotate, the fixing belt 62 is driven to rotate in the direction opposite to the rotation direction of the pressure roller 64 . do. That is, the pressure roller 64 abuts on the outer peripheral surface of the fixing belt 62 to form a fixing nip portion N between itself and the fixing belt 62 , and applies a rotational driving force to the fixing belt 62 via this fixing nip portion N. By transmitting, the fixing belt 62 is driven to rotate.

Returning to FIG. 2 , the fixing device 46 includes a temperature sensor 94 such as a thermopile that detects the surface temperature of the fixing belt 62 . Temperature sensor 94 includes, for example, a first temperature sensor that detects the surface temperature of the central portion of fixing belt 62 in the axial direction, and a second temperature sensor that detects the surface temperature of the ends of fixing belt 62 in the axial direction. Although the type of temperature sensor 94 is not particularly limited, it is preferable to use a thermopile capable of high-speed response in order to more appropriately perform the rotation failure detection process of the fixing belt 62, which will be described later.

A peeling plate 96 for preventing the paper from winding around the fixing belt 62 is provided on the downstream side of the fixing nip portion N in the paper conveying direction.

Further, the fixing device 46 includes a contact pressure changing mechanism 110 (contact/separation mechanism) capable of changing the contact pressure of the pressure roller 64 against the fixing belt 62 . In this first embodiment, the pressure unit 72 is provided with a contact pressure changing mechanism 110, and by moving the pressure roller 64 with respect to the fixing belt 62 in the separating and contacting direction, the pressure roller 64 with respect to the fixing belt 62 is adjusted. is changed. Also, the contact pressure changing mechanism 110 can completely separate the pressure roller 64 from the fixing belt 62 . An example of the contact pressure changing mechanism 110 will be described below with reference to FIGS. 4 to 6. FIG. However, the specific configuration of the contact pressure changing mechanism 110 is not limited to this.

As shown in FIGS. 4 and 5, the contact pressure changing mechanism 110 includes a pair of pressure levers 112 provided at both ends of the pressure unit 72 and extending in a direction orthogonal to the axial direction of the pressure roller 64. Prepare. Each pressure lever 112 rotatably supports the roller shaft 88 of the pressure roller 64 via a bearing 114 at its central portion. Further, each pressure lever 112 has an engagement hole 118 at one end (lower end) that engages with a pivot shaft 116 provided on the fixing frame. Rotating support shaft 116 is provided so as to extend parallel to the axial direction of fixing belt 62 , and pressure lever 112 moves in a direction (horizontal direction) to separate and contact fixing belt 62 with rotation supporting shaft 116 as a fulcrum. It is rotatable. As the pressure lever 112 rotates, the pressure roller 64 is displaced in a direction away from and in contact with the fixing belt 62 . Furthermore, each pressure lever 112 has, at its other end (upper end), a locking portion 120 that locks one end of a tension coil spring (not shown), which is an example of a biasing member. The other end of the tension coil spring is locked to the fixing frame, and the pressure lever 112 (and thus the pressure roller 64) is provided in a direction (leftward direction) in which the pressure roller 64 is pressed against the fixing belt 62. A predetermined urging force acts on .

The contact pressure changing mechanism 110 also includes a cam shaft 122 that extends parallel to the axial direction of the fixing belt 62 . Both ends of the cam shaft 122 are rotatably supported by a fixing frame. Further, on both ends of the cam shaft 122 , contact and separation cams 124 are provided at positions adjacent to the pressure lever 112 , and the pressure lever 112 is provided with a contact portion 126 with the contact and separation cam 124 . Further, a second motor 128 (see FIG. 7) is connected to one end (rear end) of the camshaft 122 via a gear or gear train (not shown). The cam shaft 122 receives a driving force from a second motor 128 and is driven to rotate about its axis in forward and reverse directions, and the contact/separation cam 124 rotates together with the cam shaft 122 .

As shown in FIG. 6, the contact/separation cam 124 has a shape in which the distance from the center of the cam shaft 122 gradually increases from Ls to Le in the region R1. Therefore, the contact/separation cam 124 receives the rotational driving force from the second motor 128, and rotates in the normal and reverse directions at the rotational position where the contact position with the contact portion 126 is the region R1, thereby applying pressure. The lever 112 can be rotated, and the contact pressure (pressing force) of the pressure roller 64 against the fixing belt 62 can be changed. Note that when the separation/contact cam 124 is in contact with the contact portion 126 at the position E where the distance from the center of the cam shaft 122 is the furthest (the state shown in FIG. 5), the pressure roller 64 is separated from the fixing belt 62. state.

In such a fixing device 46, during image formation, the fixing belt 62 maintains a predetermined fixing temperature, and the pressure roller 64 contacts the fixing belt 62 with a predetermined contact pressure (pressing force). By passing the paper through the nip portion N, the toner image is fixed on the paper. Therefore, when the temperature of the fixing belt 62 is low (e.g., 40° C. or less) at startup, etc., before forming an image on paper, the fixing belt 62 is rotated while maintaining a predetermined fixing temperature (target temperature). A warm-up operation is performed to raise the temperature to . At this time, when the temperature of the fixing belt 62 is low, the sliding oil of the fixing pad 76 has a high viscosity, and a high frictional force is generated between the fixing belt 62 and the fixing pad 76 . As a result, the fixing belt 62 slips on the pressure roller 64 , or the first motor 90 that drives the pressure roller 64 is subjected to a large load and the first motor 90 is locked. Poor rotation may occur. If the fixing belt 62 is heated in a state of improper rotation, a portion of the fixing belt 62 is rapidly heated to an abnormal temperature rise, and the fixing belt 62 is damaged such as distortion and peeling.

For this reason, in the prior art, there has been proposed a control that stops heating the fixing belt 62 when the temperature of the fixing belt 62 reaches a specified temperature (high temperature warning temperature). However, since the heat source 82 heats the fixing belt 62 from the inner surface side, the temperature sensor 94 detects the surface (outer surface) temperature of the fixing belt 62 , so there is a time lag (detection delay) corresponding to the thickness of the fixing belt 62 . As a result, the temperature of the inner surface of the fixing belt 62 may exceed the specified temperature. On the other hand, if a separate temperature sensor for detecting the temperature of the pressure roller 64 is provided as in the technique disclosed in Patent Document 1, the cost increases. Therefore, there is a need for a technique for detecting that the fixing belt 62 is in a faulty rotation state as quickly as possible with a simple configuration. In addition, a technique for properly recovering (restarting) the fixing belt 62 from a state of poor rotation is also required.

Therefore, in the first embodiment, during the warm-up period in which the temperature of the fixing belt 62 is raised to the target temperature while the fixing belt 62 is rotated, by referring to the rate of increase in the surface temperature of the fixing belt 62 (an example of temperature rise information), To quickly detect whether or not the fixing belt 62 is in a faulty rotation state. This is because when the fixing belt 62 is rotating, the temperature of the fixing belt 62 rises while being deprived of heat by the pressure roller 64. Based on the knowledge found by the inventors and confirmed by verification experiments that the temperature rise speed is faster when the roller is stopped than when it is rotating because the heat transfer from the pressure roller 64 to the pressure roller 64 is less. It is.

Further, in the first embodiment, when it is detected that the fixing belt 62 is in a faulty rotation state during warm-up, a stopping operation for stopping the heating of the fixing belt 62 and the rotation of the pressure roller 64 is executed. Further, after the stop operation, a retry operation for restarting the heating of the fixing belt 62 and the rotation of the pressure roller 64 is executed. Then, when the fixing belt 62 returns to the normal rotation state by the retry operation, a normal job such as a print job is executed. On the other hand, when the rotation failure state continues to be detected, an error notification is issued and the start-up of the fixing device 46 is stopped.

Specifically, during warm-up, the temperature sensor 94 detects the surface temperature of the fixing belt 62 at predetermined time intervals, and based on the detection result, the surface temperature rise rate X (° C./s) of the fixing belt 62 is calculated. to detect Here, the rate of increase X means the amount of temperature increase (temperature increase gradient) per predetermined time, and is calculated by X=(U _n -U _n-1 )/T. T is time (seconds) and is set to 0.1 seconds, for example. U _n is the current detected temperature (° C.), and U _n−1 is the detected temperature (° C.) T seconds before the present. When the detected rising speed X is equal to or higher than a preset threshold value Y (increasing speed threshold value, for example, 50° C./s), it is determined that the fixing belt 62 is in a faulty rotation state (slip occurs). At this time, in order to reduce erroneous detection, the detection of the rising speed X is performed a plurality of times. It is preferable to determine that it is in a state of poor rotation.

Further, in this first embodiment, the temperature sensor 94 includes a first temperature sensor for detecting the surface temperature of the central portion of the fixing belt 62 in the axial direction, and a second temperature sensor for detecting the surface temperature of the end portions of the fixing belt 62 in the axial direction. Therefore, the determination of the poor rotation state based on the rate of increase X may be made individually for both the first temperature sensor and the second temperature sensor. At this time, the threshold value Y can be set to different values for the first temperature sensor and the second temperature sensor. Then, when the rate of increase X of either the first temperature sensor or the second temperature sensor is equal to or greater than the threshold value Y, it may be determined that the fixing belt 62 is in a faulty rotation state. However, it may be determined that the fixing belt 62 is in a faulty rotation state when the rate of increase X of both the first temperature sensor and the second temperature sensor is equal to or greater than the threshold value Y. Further, the determination of the poor rotation state based on the rate of increase X can also be performed using only one of the first temperature sensor and the second temperature sensor.

Then, when it is determined that the fixing belt 62 is in a faulty rotation state based on the rising speed X, the heating of the fixing belt 62 is immediately stopped and the rotation of the pressure roller 64 is stopped. As a result, it is possible to appropriately prevent the fixing belt 62 from being damaged due to an abnormal temperature rise.

Further, after the heating rotation of the fixing belt 62 is stopped, a retry operation for restarting the heating of the fixing belt 62 and the rotation of the pressure roller 64 is executed. Then, when the fixing belt 62 returns to the normal rotation state by the retry operation, that is, when the rotation failure state is no longer detected, a normal job such as a print job is executed. On the other hand, if it is detected that the fixing belt 62 is in a faulty rotation state even after the stop operation and the retry operation are continuously performed a predetermined number of times M (for example, three times), it is determined to be abnormal (difficult to restart). Then, error notification such as maintenance display and machine trouble display is executed, and the fixing device 46 is stopped. This error notification includes displaying a trouble code on the display of the operation unit 106, turning on a warning lamp, and contacting a predetermined service using a communication line. In addition, when an abnormality occurs, operations involving printing on paper such as copying and printing using the fixing device 46 may be disabled, while operations such as scanning and facsimile not using the fixing device 46 may be enabled. A specific method of controlling the fixing device 46 during warm-up will be described later using a flow chart.

FIG. 7 is a block diagram showing an example of the electrical configuration of the image forming apparatus 10. As shown in FIG. As shown in FIG. 7, the image forming apparatus 10 includes a CPU 100, to which a RAM 102, an HDD 104, an operation unit 106, an image reading device 14, an image forming section 30, and the like are connected via a bus.

CPU 100 controls overall image forming apparatus 10 including fixing device 46 according to a program stored in HDD 104 . The CPU 100 also executes the warm-up process of the first embodiment, and functions as a temperature detector, a first failure state detector, and the like. RAM 102 is used as a working area and a buffer area for CPU 100 . HDD 104 appropriately stores a control program and necessary data for CPU 100 to control the operation of each part of image forming apparatus 10 . However, other non-volatile memory such as SSD, flash memory, EEPROM, etc. may be used instead of or in addition to the HDD.

The operation unit 106 includes a display with a touch panel, operation buttons, and the like. The display is a general-purpose monitor such as LCD, and is connected to CPU 100 via a display control circuit (not shown). The display control circuit includes GPU, VRAM, and the like. Under instructions from the CPU 100, the GPU uses the image generation data stored in the RAM 102 to generate display image data in the VRAM for displaying various screens on the display, and outputs the generated display image data to the display. . The touch panel detects a touch operation within the touch effective range and outputs touch coordinate data indicating the position of the touch operation to the CPU 100 . The operation buttons are hardware keys and include various keys or buttons such as a home button, power saving key and power button.

The image reading device 14 and the image forming section 30 are as described above, and the image forming section 30 includes the fixing device 46 and the like. The fixing device 46 also includes a heat source 82, a temperature sensor 94, a first motor 90, a second motor 128, and the like.

As described above, the heat source 82 is a heater for heating the fixing belt 62 from the inside, and includes the first lamp heater 82a and the second lamp heater 82b. Temperature sensor 94 is a sensor for detecting the surface temperature of fixing belt 62 and includes a first temperature sensor and a second temperature sensor. Temperature sensor 94 outputs a detection result (a signal corresponding to the surface temperature of fixing belt 62 ) to CPU 100 based on an instruction from CPU 100 . CPU 100 controls heat source 82 based on the result of detection by temperature sensor 94 so that the surface temperature of fixing belt 62 reaches a desired fixing temperature. Further, in the first embodiment, during warm-up, the CPU 100 calculates the rate of increase X of the surface temperature of the fixing belt 62 based on the detection result of the temperature sensor 94, and determines that the fixing belt 62 is in a faulty rotation state. to determine whether

The first motor 90 is a motor for rotating the pressure roller 64, and rotates the motor shaft based on a control signal from the CPU 100 so that the pressure roller 64 reaches a desired rotational speed. The second motor 128 is a motor for rotating the cam shaft 122 , and rotates the motor shaft so that the contact/separation cam 124 is at a desired rotational position based on a control signal from the CPU 100 . That is, the CPU 100 controls the rotational position (angle) of the motor shaft of the second motor 128 to control the rotational position of the contact/separation cam 124, thereby increasing the contact pressure between the fixing belt 62 and the pressure roller 64. Control.

FIG. 8 is a diagram showing an example of the memory map 200 of the RAM 102. As shown in FIG. As shown in FIG. 8, RAM 102 includes program storage area 202 and data storage area 204 . The program storage area 202 of the RAM 102 stores an operation detection program 202a, an image forming program 202b, a rotation failure detection program 202c, a restart program 202d, and the like.

The operation detection program 202a is a program for detecting an operation to each part of the image forming apparatus 10 including the operation unit 106. FIG. The image forming program 202b is a program for controlling components such as the photosensitive drum 36 to print a multicolor or monochromatic image on paper. The rotation failure detection program 202c calculates an increase speed X of the surface temperature of the fixing belt 62 based on the detection result of the temperature sensor 94, and determines whether or not the fixing belt 62 is in a rotation failure state based on this increase speed X. It is a program for The restart program 202d controls the heat source 82, the first motor 90, etc., and after stopping the heating rotation of the fixing belt 62, executes a retry operation of restarting the heating of the fixing belt 62 and the rotation of the pressure roller 64. It is a program for The restart program 202d includes a program for notifying an error and stopping the start of the fixing device 46 when the retry operation does not solve the problem.

Although not shown, the program storage area 202 also stores other programs for the CPU 100 to execute various functions as appropriate.

The data storage area 204 of the RAM 102 stores a set value table 204a, temperature data 204b, cam position data 204c, and the like.

The setting value table 204a includes setting values used for executing the warm-up operation in the fixing device 46, such as the target temperature of the fixing belt 62, the target rotation speed of the pressure roller 64, the target contact pressure of the pressure roller 64, and the target contact pressure of the pressure roller 64. , a detection time T (detection interval) of the temperature sensor 94 used to detect the rotation failure state of the fixing belt 62, a threshold value Y, predetermined times K, M, and other data.

The temperature data 204 b is data of the surface temperature of the fixing belt 62 , which is measured by the temperature sensor 94 . The temperature data 204b also includes the rising speed X (temperature rising gradient) calculated from the measured value of the temperature sensor 94 .

The cam position data 204c is data for identifying the cam position of the contact/disconnection cam 124. For example, the contact/disconnection cam 124 is positioned at a target position, a low contact pressure position (pressure release position), and a separated position. contains data that indicates Here, the target position is a cam position at which the contact pressure of the pressure roller 64 becomes a predetermined contact pressure (target contact pressure) corresponding to the type of paper. Further, the low contact pressure position is a cam position where the contact pressure of the pressure roller 64 is in a pressure released state (low contact pressure such that the fixing belt 62 does not slip). Further, the separated position is a cam position where the pressure roller 64 is separated from the fixing belt 62 .

Although illustration is omitted, the data storage area 204 is provided with a timer (counter) or a register necessary for executing the control program, and stores other data necessary for executing the control program.

The operation of the fixing device 46 (image forming apparatus 10 ) as described above is realized by executing the control program read out to the RAM 102 by the CPU 100 . An example of warm-up processing (rotation failure detection processing and restart processing) in the fixing device 46 will be described below with reference to the flowchart shown in FIG.

As shown in FIG. 9, when the warm-up process is started, the CPU 100 starts rotating the pressure roller 64 in step S1. Here, a control signal is sent to the first motor 90 to rotate the pressure roller 64 at a predetermined rotational speed (target rotational speed). The fixing belt 62 rotates following the rotation of the pressure roller 64 . In the next step S3, heating of the fixing belt 62 is started. That is, a control signal is sent to the heat source 82 to cause the heat source 82 to generate heat. The temperature of the fixing belt 62 rises as the heat source 82 generates heat.

In the subsequent step S5, it is determined whether or not a slip has occurred, that is, whether or not the fixing belt 62 is in a faulty rotation state. Here, the rising speed X is calculated a plurality of times from the detection results of the temperature sensor 94, and when the rising speed X exceeds the threshold value Y for K consecutive times, it is determined that the fixing belt 62 is in a faulty rotation state. If "NO" in step S5, that is, if the fixing belt 62 is not in a faulty rotation state, the process proceeds to step S7. In step S7, it is determined whether the surface temperature of the fixing belt 62 has reached the target temperature. If "NO" in step S7, wait until the fixing belt 62 reaches the target temperature, and if "YES" in step S7, proceed to step S9. In step S9, normal jobs such as copying and printing are executed, and then this process ends.

On the other hand, if "YES" in step S5, that is, if the fixing belt 62 is in a faulty rotation state, the number of times the faulty rotation state is detected is incremented, and the process proceeds to step S11. In step S<b>11 , a control signal is sent to the heat source 82 to stop heating the fixing belt 62 . In subsequent step S13, a control signal is transmitted to the first motor 90 to stop the rotation of the pressure roller 64. FIG.

In the subsequent step S15, it is determined whether or not the number of slip occurrences is equal to or greater than a predetermined number M, that is, whether or not the number of times the fixing belt 62 has been detected to be in a faulty rotation state has reached M times. If "NO" in step S15, that is, if the occurrence of slips is less than the predetermined number M, the process returns to step S1. That is, the retry operation is executed. On the other hand, if "YES" in step S15, that is, if the number of occurrences of slippage is equal to or greater than the predetermined number M, the process proceeds to step S17.

In step S17, an abnormality is notified. For example, a control signal is sent to the operation unit 106 to display a trouble code indicating that a machine trouble has occurred on the display of the operation unit 106 . In the subsequent step S19, the fixing device 46 is stopped, and then this process is terminated.

As described above, according to the first embodiment, it is determined whether or not the fixing belt 62 is in a faulty rotation state based on the speed at which the surface temperature of the fixing belt 62 rises. It is possible to quickly detect that the fixing belt 62 is in a faulty rotation state without separately providing a temperature sensor for detection or separately providing an encoder or the like for detecting the rotation of the fixing belt 62, that is, with a simple configuration. . Therefore, it is possible to appropriately prevent the fixing belt 62 from being damaged due to an abnormal temperature rise.

[Second embodiment]
Next, referring to FIG. 10, an image forming apparatus 10 according to a second embodiment of the invention will be described. The second embodiment differs from the above-described first embodiment in that the low contact pressure rotation operation is executed before the retry operation is executed. Since the other parts are the same, the parts common to the above-described first embodiment are denoted by the same reference numerals, and overlapping descriptions are omitted or simplified.

In the second embodiment, the contact pressure of the pressure roller 64 against the fixing belt 62 is set to a low contact pressure (to the extent that the fixing belt 62 does not slip) after the fixing belt 62 is detected to be in a state of poor rotation and the stop operation is executed. low contact pressure), the pressure roller 64 is rotated for a predetermined time B (for example, 1.0 second). By reducing the load of the pressure roller 64 on the fixing belt 62 in this way, the friction between the fixing belt 62 and the fixing pad 76 is reduced, and the deformation of the fixing belt 62 at the fixing nip portion N is also suppressed. As a result, the fixing belt 62 is in a state in which it is easy to rotate. In this state, the fixing belt 62 is rotated for a predetermined time B to allow the sliding oil to be applied to the fixing belt 62 and the fixing pad 76, thereby fixing at the time of the retry operation. The belt 62 is less likely to be in a faulty rotation state.

An example of warm-up processing in the fixing device 46 of the second embodiment will be described below with reference to the flowchart shown in FIG. However, since the processing of steps S21 to S39 is the same as the processing of steps S1 to S19 in the first embodiment, the explanation is omitted.

As shown in FIG. 10, if "NO" in step S35, that is, if the fixing belt 62 is not in a faulty rotation state, the CPU 100 proceeds to step S41. In step S41, the fixing pressure of the pressure roller 64 is released. That is, a control signal is sent to the second motor 128 of the contact pressure changing mechanism 110 to set the cam position of the contact/separation cam 124 to the low contact pressure position, thereby reducing the contact pressure of the pressure roller 64 against the fixing belt 62 . Apply contact pressure.

In the next step S43, a control signal is transmitted to the first motor 90 to rotate the pressure roller 64 for a predetermined time B and then stop. In subsequent step S45, the fixing pressure is restored. That is, a control signal is sent to the second motor 128, the cam position of the contact/separation cam 124 is set to the target position, and the contact pressure of the pressure roller 64 against the fixing belt 62 is set to a predetermined contact pressure corresponding to the type of paper. return. When step S45 ends, the process returns to step S21.

According to the second embodiment, similarly to the first embodiment, it is possible to quickly detect that the fixing belt 62 is in a faulty rotation state with a simple configuration. Further, since the low contact pressure rotation operation is performed before the retry operation is performed, it is possible to appropriately prevent the fixing belt 62 from being in a state of defective rotation during the retry operation. Therefore, the fixing device 46 (and thus the image forming apparatus 10) can be properly restarted.

[Third embodiment]
Next, referring to FIG. 11, an image forming apparatus 10 according to a third embodiment of the invention will be described. The third embodiment differs from the above-described second embodiment in that if it is detected that the fixing belt 62 is in a faulty rotation state during the low contact pressure rotation operation, the heating rotation operation is executed. Since other parts are the same, parts common to the above-described first and second embodiments are denoted by the same reference numerals, and overlapping descriptions are omitted or simplified.

In the third embodiment, the CPU 100 refers to the surface temperature drop rate (an example of temperature drop information) of the fixing belt 62 during the above-described low contact pressure rotation operation, and determines whether the fixing belt 62 is in a state of defective rotation. quickly detect whether or not That is, the CPU 100 also functions as a second failure state detection section. Contrary to the heating of the fixing belt 62, the inventors have found that the temperature drop rate is lower when the fixing belt 62 is not heated than when the fixing belt 62 is not rotating. , based on findings confirmed by verification experiments.

Specifically, during the low contact pressure rotation operation, the surface temperature of the fixing belt 62 is detected by the temperature sensor 94 at predetermined time intervals, and based on the detection result, the surface temperature of the fixing belt 62 decreases at a speed P ( °C/s) is detected. Here, the drop rate P means the amount of temperature drop (temperature drop gradient) per predetermined time, and is calculated by P=(U _n−1 −U _n )/T. T is time (seconds) and is set to 0.1 seconds, for example. U _n is the current detected temperature (° C.), and U _n−1 is the detected temperature (° C.) T seconds before the present. When the calculated descending speed P is equal to or less than a preset threshold value Q (descending speed threshold value, eg, 10° C./s), it is determined that the fixing belt 62 is in a faulty rotation state (slip occurs). At this time, in order to reduce erroneous detection, detection of the descent speed P is performed a plurality of times. It is preferable to determine that it is in a state of poor rotation. Similar to the above-described embodiment, the determination of the poor rotation state based on the descent rate P may be made individually for both the first temperature sensor and the second temperature sensor.

When it is detected that the fixing belt 62 is in a faulty rotation state during the low contact pressure rotation operation, the fixing belt 62 is heated and applied while the contact pressure of the pressure roller 64 is kept at the low contact pressure. A heating rotation operation is executed to rotate the pressure roller 64 for a predetermined time C (for example, 3 seconds). When the fixing belt 62 is in a low contact pressure state (uncompressed state), it becomes easier to rotate. However, if rotation failure occurs even in this state, it is considered that sliding oil adheres or the fixing belt 62 is severely deformed. Therefore, when it is detected that the fixing belt 62 is in a faulty rotation state during the low contact pressure rotation operation, the heat rotation operation is executed to alleviate adhesion of sliding oil and deformation of the fixing belt 62 . When performing this heating and rotating operation, the output of the heat source 82 is set to a state (for example, 50% output) lower than the normal output (during temperature control), and the heating of the fixing belt 62 is set to a low heating state. is preferred. A known method may be used to reduce the amount of heating. For example, the power supplied to the heat source 82 may be reduced by reducing the phase angle for phase control and thinning the wave number for wavenumber control.

An example of warm-up processing in the fixing device 46 of the third embodiment will be described below with reference to the flowchart shown in FIG. However, since the processes of steps S51 to S73 and S79 are the same as the processes of steps S21 to S45 of the first embodiment, description thereof will be omitted.

As shown in FIG. 11, the process of step S75 is performed following the process of step S73. In step S75, it is determined whether or not a slip has occurred while the pressure roller 64 is being rotated in step S73, that is, whether or not the fixing belt 62 is in a faulty rotation state. Here, the descent speed P is calculated a plurality of times from the detection result by the temperature sensor 94 while the pressure roller 64 is rotating, and when the descent speed P becomes equal to or less than the threshold value Q for L consecutive times, the fixing belt 62 is determined to be in a bad rotation state. If "NO" in step S75, that is, if the fixing belt 62 is not in a faulty rotation state, the process proceeds to step S79.

On the other hand, if "YES" in step S75, that is, if the fixing belt 62 is in a faulty rotation state, the process proceeds to step S77. In step S77, a control signal is sent to the heat source 82 and the first motor 90 to rotate the pressure roller 64 while heating the fixing belt 62 for a predetermined time C. As shown in FIG. After the process of step S77 is completed, the process proceeds to step S79.

According to the third embodiment, similarly to the first embodiment, it is possible to quickly detect that the fixing belt 62 is in a faulty rotation state with a simple configuration. In addition, since the heating rotation operation is executed when it is detected that the fixing belt 62 is in a rotational failure state during the low contact pressure rotation operation, the fixing belt 62 is more appropriately prevented from being in a rotation failure state during the retry operation. can. Therefore, the fixing device 46 can be restarted more appropriately.

In each of the above-described embodiments, one preset value is used as the threshold value Y (increase speed threshold value) for determining whether the fixing belt 62 is in a faulty rotation state. That is, the threshold value Y can be changed according to the voltage supplied to the image forming apparatus 10). It is preferable to change the threshold Y in proportion to the change in the supply voltage or correct the threshold Y according to the characteristics of the heat source 82 to set the threshold Y suitable for the supply voltage at that time. For example, if the threshold Y is set to 50° C./s when the supply voltage is 100 V, change the threshold Y to 45° C./s when the detected supply voltage is 95 V, or change the detected supply voltage to 45° C./s. is 105 V, the threshold Y may be changed to 55° C./s. Specifically, as another embodiment, a threshold storage unit that stores a plurality of threshold values Y set according to the value of the supply voltage to the fixing device 46, and a supply voltage detection that detects the supply voltage to the fixing device 46. section is provided in the image forming apparatus 10 . Then, the CPU 100 functioning as the first failure state detection unit selects the threshold value Y from among the plurality of threshold values Y stored in the threshold storage unit based on the supply voltage detected by the supply voltage detection unit, and the rate of increase X is greater than or equal to the selected threshold value Y, it is detected that the fixing belt 62 is in a faulty rotation state.

As another embodiment, the cumulative number of times the fixing belt 62 is detected to be in a faulty rotation state (the total number from the time the fixing belt 62 is started to be used (at the time of replacement) to the present) is stored in the HDD 104 or the like together with the number of sheets passed. can be stored in a storage unit (accumulated number storage unit), and the accumulated number can be displayed on a display unit such as a display of the operation unit 106 . For example, the stored cumulative number of times may be used as a specified value that specifies the life (lifetime or replacement time) of the fixing belt 62 . Conventionally, the life of the fixing belt 62 is defined by the number of sheets passed (for example, set to 300,000 sheets). If the number of times is specified (for example, set to 1000 times), replacement of the fixing belt 62 can be prompted more appropriately in a usage situation where belt slip occurs frequently.

In each of the above-described embodiments, the image forming apparatus 10 is a multifunction machine combining a copier, a facsimile machine, a printer, and the like. A multi-function machine combining at least two of these may be used.

Moreover, the specific numerical values, materials, and the like given above are merely examples, and can be appropriately changed according to requirements such as product specifications.

DESCRIPTION OF SYMBOLS 10... Image forming apparatus 30... Image forming part 46... Fixing device 62... Fixing belt (fixing rotator)
64 pressure roller (pressure rotating body)
82 ... heat source 90 ... first motor (motor for pressure roller)
92 ... current sensor 94 ... temperature sensor 100 ... CPU
REFERENCE SIGNS LIST 110: contact pressure changing mechanism 124: contact/separation cam 128: second motor (motor for contact/separation cam)

Claims (7)

A fixing device for thermally fixing a toner image formed on a recording medium,
fixing rotating body,
a heat source for heating the fixing rotating body;
a pressurizing rotator that abuts on the outer peripheral surface of the fixing rotator to form a nip portion with the fixing rotator and causes the fixing rotator to be driven to rotate;
a motor that rotates the pressurizing rotor;
a temperature detection unit that detects the surface temperature of the fixing rotating body;
During warm-up, in which the temperature of the fixing rotator is raised to a target temperature while the fixing rotator is rotating, the fixing rotator is in a faulty rotation state based on the temperature rise information of the surface temperature of the fixing rotator detected by the temperature detection unit. and a first failure state detection section for detecting whether or not there is a rotation failure state of the fixing rotating body, the heat source and the motor are controlled to A fixing device comprising a control unit that performs a stop operation for stopping heating of a fixing rotary member and rotation of the pressure rotary member. After executing the stopping operation, the control unit executes a retry operation for restarting the heating of the fixing rotary member and the rotation of the pressure rotary member, and continuously executes the stopping operation and the retry operation a predetermined number of times. 2. The fixing device according to claim 1, wherein when said first failure state detecting section detects that said fixing rotating member is in a rotation failure state after said fixing, an error notification is executed and said fixing device is stopped from starting up. Device. a contact pressure changing mechanism capable of changing the contact pressure of the pressurizing rotator with respect to the fixing rotator;
After executing the stop operation and before executing the retry operation, the control unit controls the contact pressure changing mechanism and the motor so that the pressing rotator contacts the fixing rotator. 3. The fixing device according to claim 2, wherein a low contact pressure rotation operation is performed in which the pressure rotating body is rotated for a predetermined time while the contact pressure is set to a low contact pressure. When performing the low contact pressure rotation operation, it is detected whether or not the fixing rotator is in a faulty rotation state based on the temperature drop information of the surface temperature of the fixing rotator detected by the temperature detecting section. 2 includes a failure state detection unit,
The controller controls the heat source and the motor to heat the fixing rotator while heating the fixing rotator when the second failure state detection unit detects that the fixing rotator is in a malfunctioning state. 4. The fixing device according to claim 3, wherein a heating rotation operation is performed by rotating the pressure rotator for a predetermined time. a threshold storage unit that stores a plurality of rising speed thresholds set according to the value of the voltage supplied to the fixing device; and a supply voltage detection unit that detects the voltage supplied to the fixing device,
The first failure state detection section detects the fixing rotation speed when the rate of temperature increase detected by the temperature detection section is equal to or higher than the rate of increase threshold selected based on the supply voltage detected by the supply voltage detection section. 5. The fixing device according to any one of claims 1 to 4, which detects that the body is in a bad rotation state. an accumulated number storage unit for storing an accumulated number of times that the fixing rotary member is detected to be in a rotation failure state by the first failure state detection unit;
The fixing device according to any one of claims 1 to 5, further comprising a display section capable of displaying the cumulative number of times. An image forming apparatus comprising the fixing device according to claim 1 .

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