Fixing device

Abstract

To suppress the positional deviation of a fixing belt in the width direction.SOLUTION: Provided is a fixing device that forms a nipple part together with a pressure rotor via a fixing belt. At the nipple part, the fixing belt and the pressure rotor apply heat and pressure to a recording material carrying a toner image, thereby fixing the toner image to the recording material. The fixing device has a suspension member that suspends the fixing belt, and also has a movement mechanism that, when the pressure rotor is located at a position to release a pressing force to the fixing belt, causes movement to a press position where the suspension member presses the fixing belt from the inner circumferential face toward the outer circumferential face of the fixing belt and a release position where the pressing force exerted to the fixing belt by the suspension member is released.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a fixing device for fixing a toner image onto a recording material. [Background technology]

[0002] 2. Description of the Related Art Conventionally, an electrophotographic image forming apparatus includes a fixing device that fixes a toner image formed on a recording material onto the recording material.

[0003] One known fixing device has a configuration that uses a fixing belt, which is an endless belt (Patent Document 1). The fixing belt is suspended by a plurality of members including a heating roller having a heat source. The heating roller heats the fixing belt. One of the members that suspends the fixing belt includes a nip forming member. The nip forming member forms a nip portion together with a pressure rotating body via the fixing belt. When a recording material carrying a toner image is transported to the nip portion, heat and pressure are applied to the recording material, and the toner image is fixed to the recording material.

[0004] In addition, the fixing device described in Patent Document 1 discloses that the position of the fixing belt is detected by a photosensor via a flag. Based on the detection result of the photosensor, the position of the fixing belt in the width direction is controlled by tilting a steering roller that suspends the fixing belt. In order to control the position of the fixing belt in the width direction of the fixing belt, the steering roller is pressed against the fixing belt. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-33204 Summary of the Invention [Problem to be solved by the invention]

[0006] In a fixing device having a fixing belt suspended by a plurality of suspension members, the fixing device is subjected to vibrations during transportation, etc. The vibrations cause the fixing device to shake, which may cause the suspended fixing belt to shift in the width direction.

[0007] SUMMARY OF THE PRESENTLY PREFERRED EMBODIMENTS In view of the above, an object of the present invention is to suppress misalignment of a fixing belt in the width direction. [Means for solving the problem]

[0008] In consideration of the above problems, a fixing device according to the present invention includes a rotatable endless fixing belt, a heating roller that contacts an inner circumferential surface of the fixing belt and applies heat to the fixing belt, a suspension member that contacts the inner circumferential surface of the fixing belt together with the heating roller and is tiltably arranged to change the position of the fixing belt in the width direction of the fixing belt, a pressure rotating body that presses the fixing belt, and the pressure rotating body can move between a position where it presses the fixing belt and a position where it releases the pressure on the fixing belt, and a nip forming member that forms a nip portion together with the pressure rotating body via the fixing belt, and in the nip portion, the fixing belt and the pressure rotating body apply heat and pressure to a recording material carrying a toner image, thereby fixing the toner image to the recording material, and when the pressure rotating body is located at a position where it releases the pressure on the fixing belt, To , the suspension member teeth, The fixing belt is moved to a pressing position where the fixing belt is pressed from the inner peripheral surface to the outer peripheral surface, and to a releasing position where the pressure of the suspension member against the fixing belt is released. a spring that presses the suspension member from the inner circumferential surface of the fixing belt toward the outer circumferential surface thereof, and a locking member that fixes the suspension member at the release position against the pressure of the spring from the inner circumferential surface of the fixing belt toward the outer circumferential surface thereof, the locking member being The suspension member is characterized in that it is provided at both ends of the suspension member in the longitudinal direction of the suspension member. Effect of the Invention

[0009] According to the fixing device of the present invention, it is possible to prevent the fixing belt from being misaligned in the width direction. [Brief description of the drawings]

[0010] [Figure 1] 1 is a cross-sectional view of an image forming apparatus according to an embodiment of the present invention. [Diagram 2] 2 is a cross-sectional view of the fixing device according to the embodiment. [Diagram 3] FIG. 2 is a partial perspective view of the fixing device according to the first embodiment. [Figure 4] 2 is a side view of one end of the fixing device according to the first embodiment. FIG. [Diagram 5] FIG. 11 is a perspective view of a fixing device according to a second embodiment. [Figure 6] FIG. 11 is a partial perspective view of one end side of a fixing device according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] <Example 1> <Image forming device> A first embodiment of the present invention will be described. Although a full-color copying machine having a plurality of photosensitive drums has been described as the present embodiment, the present invention can also be applied to a monochrome copying machine or printer having one photosensitive drum. Therefore, the present embodiment is not limited to a full-color laser beam printer. First, an outline of the image forming operation will be described. FIG. 1 is a main cross-sectional view showing the overall configuration of an image forming apparatus 100.

[0012] <Image forming device> This image forming apparatus 100 conveys the recording material P conveyed from the recording material storage section 103 to the image forming section 110, and forms a toner image on the recording material P. Thereafter, the image forming apparatus 100 conveys the recording material P on which the toner image has been formed by the image forming section 110 to the fixing device 200, and fixes the unfixed toner on the recording material P to the recording material P by applying heat and pressure. The recording material P is, for example, a sheet of paper or an OHP.

[0013] The image forming apparatus 100 has an image forming unit 110. The image forming unit 110 forms yellow, magenta, cyan, and black toner images on an intermediate transfer belt 115. The image forming unit 110 includes four types of image forming units 110 arranged along the movement direction of the intermediate transfer belt 115: a yellow image forming unit 120a, a magenta image forming unit 120b, a cyan image forming unit 120c, and a black image forming unit 120d.

[0014] The image formation process will be described by taking the yellow image forming unit 120a as an example. The photoconductor drum 111 as an image carrier rotates counterclockwise in FIG. 1. The primary charger 112 charges the photoconductor drum 111 to a uniform surface potential. The laser unit 113 has a light source that outputs laser light and forms a latent image on the photoconductor drum 111. The developer 114 develops the latent image formed on the photoconductor drum 111 using a developer containing toner to form a toner image. In the other image forming units 120b to d, toner images are formed in the same manner as in 120a.

[0015] The toner images formed by the image forming units 120a, 120b, 120c, and 120d are transferred onto an intermediate transfer belt 115. A transfer roller 116 transfers the toner image on the intermediate transfer belt 115 onto a recording material P conveyed from a recording material storage unit 103.

[0016] The fixing device 200 applies heat and pressure to the recording material P, thereby fixing the toner image transferred onto the recording material P to the recording material P. The fixing device 200 includes a fixing belt 201, a pressure roller 202, and the like.

[0017] In the case of single-sided printing, the image forming apparatus 100 discharges the recording material P, which has passed through the image forming unit 110 and the fixing device 200 and on which image formation has been completed, to the outside by guiding it to a discharge path 139 by a flapper 132. The flapper 132 is a guide member for guiding the recording material P, which has passed through the image forming unit 110 and the fixing device 200, to a conveying path 134 or to the outside of the image forming apparatus 100.

[0018] On the other hand, in the case of double-sided printing, the image forming apparatus 100 inverts the recording material P after printing on one side and conveys it again to the image forming unit 110. Specifically, the recording material P after fixing is guided by a flapper 132 to a conveying path 134 and conveyed to an inverting unit 136. When an inversion sensor 135 detects the rear end of the recording material P, a flapper 133 switches the conveying direction of the recording material P to a conveying path 137. The image forming apparatus 100 conveys the inverted recording material P again to the image forming unit 110 and further to the fixing device 200 via the conveying path 137. The recording material P after printing on both sides is guided by the flapper 132 to a discharge path 139 and discharged to the outside.

[0019] The operation unit 180 includes a display screen and selection keys. The operation unit 180 displays the status of the image forming apparatus 100 on the display screen and accepts operation instructions from an operator (user) via the selection keys.

[0020] The control board 150 has a control unit 151 and a memory 152, and controls each unit in the image forming apparatus 100 described above. The control unit 151 outputs an output signal to each electric component to operate the electric component at a desired timing and with a required amount of control, based on detection signals input from each sensor and information stored in the memory 152. Therefore, it is this control unit 151 that actually controls the electric components. The memory 152 stores information data required for controlling each unit, and the control unit 151 reads and writes the information data stored in the memory 152.

[0021] Next, the configuration of the fixing device in this embodiment will be described in detail with reference to Figures 2 and 3. Figure 2 is a cross-sectional view of the fixing device in this embodiment of the invention, and Figure 3 is a partial perspective view of fixing device 200.

[0022] <Fixing device> FIG. 2 shows a schematic diagram of the overall configuration of a fixing device 200 of a belt heating type according to an embodiment of the present invention. In FIG. 2, the recording material P is conveyed from right to left. The fixing device 200 has a heating unit 210 having a heat source and a pressure roller 202 as a pressure rotating body. First, the heating unit 210 will be described. The heating unit 210 has a fixing belt (hereinafter, belt) 201 as an endless rotatable heating rotating body. A nip forming member (hereinafter, pad) 203 that forms a nip portion, a heating roller 204 having a halogen heater, and a steering roller 205 that controls the position of the belt are in contact with the inner peripheral surface of the belt 201. As a result, the belt 201 is suspended. The pad 203 forms a nip portion N together with the pressure roller via the belt 201.

[0023] The belt 201 has thermal conductivity, heat resistance, and the like, and is a thin cylindrical shape. In this embodiment, it has a three-layer structure including a base layer, an elastic layer on the outer periphery of the base layer, and a release layer on the outer periphery of the elastic layer. The base layer is 60 μm thick and made of polyimide resin (PI). The elastic layer is 300 μm thick and made of silicone rubber. The release layer is 30 μm thick and made of PFA (tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin) as a fluororesin. The pad 203 is a member that is in pressure contact with the pressure roller 202 via the belt 201 to form a nip portion N of a predetermined width in the recording material conveying direction. The cross section is approximately rectangular, and the pad is a long member along the width direction of the belt 201. The pad 203 needs to be heat-resistant, and is made of LCP (liquid crystal polymer) resin.

[0024] Between pad 203 and belt 201, there is interposed lubricating sheet 207 whose surface is coated with PTFE, and silicone oil S (hereinafter, oil S) as a lubricant, so that belt 201 slides smoothly against pad 203. Lubricating sheet 207 is formed by coating the surface of a 70 μm-thick polyimide base material with PTFE. Note that lubricating sheet 207 is arranged to improve the sliding properties between pad 203 and fixing belt 201, and it is possible to substitute sliding sheet 207 by applying a coating that improves sliding properties to the surface layer of pad 203.

[0025] The pressure roller 202 is a roller in which an elastic layer is formed on the outer circumference of the shaft, and a release layer is formed on the outer circumference of the elastic layer. The shaft is made of stainless steel, the elastic layer is 5 mm thick and made of conductive silicone rubber, and the release layer is 50 μm thick and made of PFA as a fluororesin. The pressure roller 202 is supported by the fixing frame 380 of the fixing device 200, and a gear is fixed to one end of the pressure roller 202, which is connected to a driving source M via the gear and is driven to rotate. The belt 201 rotates in the R direction by being held by the rotating pressure roller 202 and pad 203. The pressure roller 202 is held by bearings at both ends, and can be moved by an attachment / detachment means (not shown) between a position where the pressure roller 202 presses the belt 201 to form a nip portion N and a position where the pressure roller 202 releases the pressure roller 202 from the belt 201. When the pressure roller 202 releases the pressure roller 202 from the belt 201, the pressure roller 202 may be separated from the belt 201. It is sufficient that the pressure on the belt 201 is released and the restraining force on the belt 201 is weakened. In a state where the nip portion N is formed by the pressure roller 202 and the belt 201, a pressing force of about 1000 N acts.

[0026] If the pressure roller 202 is left in the nip portion N while the rotation of the pressure roller 202 is stopped, distortion occurs in a part of the rubber portion in the circumferential direction. This may cause uneven rotation of the pressure roller 202 and uneven surface properties. For this reason, when the image forming apparatus is not used, for example, when the image forming apparatus is transported from the manufacturer to the user, it is necessary to hold the pressure roller 202 in the position where the pressure is released (the state shown in FIG. 2). In this embodiment, when a cover (not shown) is opened and when the image forming apparatus 100 is turned off in order to remove the fixing device 200 from the image forming apparatus 100, the pressure roller 202 is moved to the above-mentioned separated position.

[0027] The oil supply roller 208 is formed by impregnating a roll-shaped member wrapped with a nonwoven fabric having a thickness of 100 μm with silicone oil. The oil supply roller 208 is abutted against the inner surface of the fixing belt 201 at 3.0 N by a pressure spring 209, and is supported by the frame of the heating unit 210 so as to be rotatable by the roller.

[0028] The oil S applied as a lubricant between the pad 203 and the belt 201 deteriorates with the operation of the fixing device 200 and is reduced due to leakage to the outside, etc. If the oil S between the pad 203 and the belt 201 cannot be retained, the sliding resistance between the pad 203 and the belt 201 increases, and problems such as poor rotation of the belt 201 may occur. The oil supply roller 208 comes into contact with the belt 201, making it possible to supply the oil S to the inner peripheral surface of the belt 201. This makes it possible to maintain the oil S between the belt 201 and the pad 203 (sliding sheet 207) for a longer period of time, and to maintain stable operation of the fixing device 200.

[0029] The stay 206 is disposed inside the pad 203 (opposite the sliding sheet 207 side) and is a reinforcing member having rigidity that is long in the width direction of the belt 201 to back up the pad 203. The material used is a 3 mm thick drawn SUS304 material, which is formed into a hollow "square" shaped cross section to ensure strength. When the pad 203 is pressed against the pressure roller 202, the stay 206 provides strength to the pad 203 to ensure the pressure at the nip N. Note that the material of the stay 206 is not limited to stainless steel as long as strength can be ensured.

[0030] The heating roller 204 is a stainless steel pipe with a thickness of 1 mm and an outer diameter of 80 mm, and has a halogen heater (not shown) disposed inside, capable of generating heat up to a predetermined temperature. The belt 201 is heated by the heating roller 204, and is controlled to a predetermined target temperature according to the paper type based on temperature detection by a thermistor.

[0031] Steering roller 205, which serves as a suspension member for suspending belt 201, suspends fixing belt 201 and is supported by steering frame 213 via steering bearing 221. In this embodiment, steering roller 205 is configured by forming a 200 μm-thick silicone rubber on the surface of a hollow stainless steel roll having an outer diameter of 20 mm. Steering roller 205 is rotatably supported by steering roller shaft 223 via a bearing.

[0032] Both ends of steering roller shaft 223 are supported by a pair of steering bearings 221. Steering bearings 221 are made of a resin material such as PPS that can be used in high-temperature environments, and are movably attached along the side wall of box-shaped steering frame 213. Steering bearings 221 are pressed by springs 211 supported by steering frame 213, which urges steering roller 205 toward fixing belt 201. As a result, fixing belt 201 is suspended with tension between steering roller 205, heating roller 204, and pad 203. In this suspended state, steering roller 205 is in contact with fixing belt 201 with a force of 20 N by springs 211.

[0033] The steering frame 213 rotates with respect to the frame of the heating unit 210 around the pivot shaft 212, thereby changing the alignment of the steering roller 205 with respect to the other suspension members. This generates a tension difference between the front and rear of the fixing belt 201, controlling the position of the belt 201 in the main scanning direction.

[0034] In a separated state where the fixing belt 201 and the pressure roller 202 are separated, the contact force between the pad 203 and the fixing belt 201 is weak, so that in the separated state, the position of the fixing belt 201 in the main scanning direction is held by the heating roller 204 and the steering roller 205. If the image forming apparatus is subjected to vibration during transportation, the heating roller 204 and the steering roller 205 also vibrate and move in the main scanning direction, which is the width direction of the belt 201. At this time, the fixing belt 201 is held by the heating roller 204, which has a large binding force, and vibrates. However, compared to the heating roller 204, the steering roller 205, which has a smaller contact area with the belt 201, has a smaller binding force for binding the belt 201. Then, the position of the belt 201 in contact with the steering roller 205 is shifted due to the vibration. Due to the influence of the binding force of the steering roller 205, a relative positional deviation occurs with respect to the heating roller 204. For example, if the belt 201 is significantly shifted in the width direction, the positional deviation is detected and an error occurs.

[0035] By using the tension releasing means in this embodiment, the pressing force of the steering roller 205 against the fixing belt 201 can be reduced, so that it is possible to suppress the positional deviation of the fixing belt 201 caused by the difference in the binding force described above. The details are described below.

[0036] The mechanism for moving the suspension member in this embodiment will be described. Fig. 4 is a partial perspective view of the fixing device 200 for explaining a state in which the tension of the steering roller 205 is released by the steering lock arm 222 described later. In order to achieve the state shown in Figs. 3 and 4, it is necessary to remove the fixing device 200 from the image forming apparatus 100 and perform an operation on the housing, such as removing the cover. Therefore, the pressure roller 202 is moved to a position where the pressure against the fixing belt 201 is released.

[0037] In the longitudinal direction of the steering roller 205, steering lock arms 222 are held at both ends of the steering frame 213. During image formation, the belt 201 must be suspended under tension. If image formation is performed with the tension loosened, the belt 201 may become wavy, causing paper wrinkles, etc. Therefore, the steering roller 205 presses against the belt 201 during image formation. This causes the belt 201 to be suspended under tension. The position of the steering roller 205 pressing against the belt 201 is referred to as the pressing position. The pressing direction of the steering roller 205 against the belt 201 is the direction from the inner peripheral surface to the outer peripheral surface of the belt 201. The direction from the inner peripheral surface to the outer peripheral surface of the belt 201 may include a force component from the inner peripheral surface to the outer peripheral surface of the belt 201.

[0038] The steering lock arm 222 is formed of a wire spring with a wire diameter of 1 mm, and is rotatably attached to the steering frame 213. The support portion 221 is formed with an attachment surface 221a to which the steering lock arm 222 is attached. By hanging the steering lock arm 222 on the attachment surface 221a while pressing the steering roller 205 in the opposite direction to the pressing direction of the spring 211, the steering roller 205 is held in a position retracted from the position where the fixing belt 201 is suspended (release position). This reduces the contact force with the fixing belt 201, and makes it possible to weaken the tension applied to the fixing belt 201 (state of FIG. 4). In this embodiment, the attachment surfaces 221a are provided at both ends of the steering roller 205. When the steering roller 205 is positioned at the release position, the steering lock arm 222 is attached to the attachment surfaces 221a at both ends. This makes it possible to weaken the tension at both ends of the steering roller 205.

[0039] In this embodiment, the steering roller 205 can be moved in a direction away from the belt 201 by 5 mm (in the direction of the arrow in FIG. 4) by hanging the steering lock arm 222 on the mounting surface 221a. This causes the steering roller 205 to be separated from the belt 201. The position where the tension applied to the belt 201 by the steering roller 205 is weakened is the release position. When the steering roller 205 is in the release position, the belt 201 can be easily removed and attached, so that the fixing belt 201 can be replaced. It has been described above that when the steering roller 205 is in the release position, it is in a state where it is separated from the belt 201. However, this is not limited to this. The release position may be a position where the force with which the steering roller 205 presses the belt 201 is weakened compared to the pressing position. In other words, it is acceptable for the inner circumferential surface of the belt 201 and the steering roller 205 to be in contact. If the steering roller 205 is in a position separated from the belt 201, it is considered that there is no force pressing the belt 201, so it is even better if it is separated.

[0040] When the steering roller 205 is in the release position, the tension of the belt 201 decreases, so that the belt 201 sags due to its own weight. Therefore, when comparing the pressing position and the release position, the contact area between the belt 201 and the heating roller 204 is larger in the release position.

[0041] As described above, by placing the steering roller 205 in the release position before transporting the fixing device, it is possible to prevent the belt 201 from shifting in position during transportation. Therefore, the position of the steering roller 205 before use of the fixing device is the release position.

[0042] Oil S is applied to the inside of fixing belt 201. The oil S is set to have a kinetic viscosity of 50 to 500 CST at high temperatures in order to satisfy the desired sliding performance at high temperatures during fixing operation. When the image forming apparatus is transported from the manufacturer to the user, the heating unit 210 described above does not operate, so the viscosity of oil S becomes high. Therefore, heating roller 204 and steering roller 205, which suspend fixing belt 201, come into close contact with fixing belt 201 via oil S. The contact area of ​​fixing belt 201 with heating roller 204 is larger than the contact area with steering roller 205, so the binding force of heating roller 204 is also larger.

[0043] <Example 2> A second embodiment of the present invention will be described below. Note that the configurations and operations of an image forming apparatus 100 and a fixing device 200 are almost the same as those of the first embodiment, so the description will be omitted.

[0044] The details of the fixing device configuration in this embodiment will be described. Fig. 5 is a perspective view of the fixing device in the embodiment of the present invention, and Fig. 6 is a partial perspective view of fixing device 200. To achieve the state shown in Figs. 5 and 6, fixing device 200 needs to be removed from image forming apparatus 100 to expose the housing such as a cover. Therefore, pressure roller 202 is moved to a separated position separated from fixing belt 201.

[0045] The fixing device 200 is configured to be removable when the cover of the image forming apparatus 100 is opened. The fixing device 200 has a fixing belt 201 and a steering roller 205 suspended therearound covered by a fixing cover 250. When performing maintenance on the internal components of the fixing device 200, the fixing cover 250 can be opened to access the fixing belt 201, etc.

[0046] The fixing cover 250 is formed by a cover portion 251 formed of resin and a metal plate portion 252 that holds the cover portion. An opening 302 is formed in the cover portion 251 and the plate portion 252, and a fixing member 301 can be attached from outside the fixing device 200 by communicating with the opening 302. FIG. 5 illustrates a state in which the fixing member 301 is attached. The fixing member 301 is an iron plate member, and is formed with a lock portion 301a that presses the steering bearing 221 and a restricting portion 301b that contacts the plate portion 250b. A guide hole 252a through which the fixing member 301 passes and a contact portion 252b that contacts the lock portion 301a are formed in the opening of the plate portion 250b.

[0047] When attaching the fixed member 301, first, the fixed member 301 is passed through the guide hole 252a described above, and the lock portion 301a presses the pressing surface 221c of the steering bearing 221. Next, the fixed member 301 is slid while pressing the steering roller 205 in the opposite direction to the pressing direction of the spring 211, and the restricting portion 301b abuts against the contact portion 252b. As a result, the spring force of the spring 211 pressing the steering roller 205 is received by the restricting portion 252b of the plate portion 252, and it becomes possible to hold the steering roller 205 in a pressed state.

[0048] In this embodiment, the fixed member 301 holds down the steering bearing 221, so that the steering roller 205 can be moved in a direction away from the belt 201 by 5 mm (in the direction of the arrow in FIG. 4). This causes the steering roller 205 to be separated from the belt 201. The position where the tension applied to the belt 201 by the steering roller 205 is weakened is set as the release position. When the steering roller 205 is in the release position, the belt 201 can be easily removed and attached, so that the fixing belt 201 can be replaced. It has been described above that when the steering roller 205 is in the release position, it is in a state where it is separated from the belt 201. However, this is not limited to this. The release position may be a position where the force with which the steering roller 205 presses the belt 201 is weakened compared to the pressing position. In other words, it is acceptable for the inner circumferential surface of the belt 201 and the steering roller 205 to be in contact. If the steering roller 205 is in a position separated from the belt 201, it is considered that there is no force pressing the belt 201, so it is better if it is separated. The effect of separating the steering roller 205 is the same as that of the first embodiment.

[0049] The fixing member 301 can be removed by reversing the above procedure, but it can also be removed by separating the fixing member 301 from the steering bearing 221 by opening the fixing cover, for example.

[0050] In addition, in the present embodiment, a method for attaching fixed member 301 to fixing cover 250, which is a component of fixing device 200, has been described, but it is sufficient that steering bearing 221 is pressed and held by fixed member 301. For example, the same effect can be obtained with the frame of fixing device 200 or the cover of image forming apparatus 100, if there is an opening for attaching fixed member 301 and a portion for fixing. [Explanation of symbols]

[0051] 100 Image forming device 200 Fixing device 201 Fixing belt 202 Pressure roller 203 Pad 204 Heating roller 205 Steering roller 210 Heating Unit 222 Steer Lock Arm 223 Steering roller shaft

Claims

1. a rotatable endless fixing belt; a heating roller that contacts an inner circumferential surface of the fixing belt and applies heat to the fixing belt; a suspension member that is in contact with an inner circumferential surface of the fixing belt together with the heating roller and is tiltably provided so as to change a position of the fixing belt in a width direction of the fixing belt; a pressure rotating body that applies pressure to the fixing belt; the pressure rotating body can be moved between a position where it presses the fixing belt and a position where it releases the pressure on the fixing belt, a nip forming member that forms a nip portion together with the pressure rotating body via the fixing belt; In the nip portion, the fixing belt and the pressure rotating member apply heat and pressure to the recording material carrying the toner image, thereby fixing the toner image to the recording material, when the pressure rotating body is located at a position where the pressure against the fixing belt is released, the suspension member is movable between a pressing position where the suspension member presses the fixing belt from the inner peripheral surface toward the outer peripheral surface of the fixing belt and a releasing position where the suspension member releases the pressure against the fixing belt, a spring that presses the suspension member from the inner circumferential surface of the fixing belt toward the outer circumferential surface of the fixing belt; a locking member for fixing the suspension member at the release position against the pressure of the spring from the inner peripheral surface of the fixing belt toward the outer peripheral surface of the fixing belt; Equipped with The locking members are provided at both ends of the suspension member in the longitudinal direction of the suspension member. A fixing device comprising:

2. 2. The fixing device according to claim 1, wherein the suspension member is located at the release position before the fixing device is used.

3. 2. The fixing device according to claim 1, wherein the suspension member is a steering roller.

4. 2. The fixing device according to claim 1, wherein when the suspension member is located at the pressing position, a contact area between the heating roller and the fixing belt is larger than a contact area between the suspension member and the fixing belt.

5. 2. The fixing device according to claim 1, wherein the contact area between the heating roller and the fixing belt is smaller when the suspension member is in the pressing position than when the suspension member is in the release position.

6. 2. The fixing device according to claim 1, wherein the suspension member is in contact with an inner circumferential surface of the fixing belt when the suspension member is located at the release position.

7. 2. The fixing device according to claim 1, wherein the locking member is formed of a wire spring.

8. 2. The fixing device according to claim 1, wherein the locking member can be attached in a state where the locking member is pressed against the fixing belt in a direction opposite to the pressing direction of the suspension member against the fixing belt.

Images