JP2024072360A - Fixing device and image forming apparatus - Google Patents

Abstract

[Problem] To provide a fixing device capable of improving the positioning accuracy of a transport guide member relative to a fixing member supported by a fixing structure. [Solution] In the fixing device, which includes a pair of fixing members (60, 62) that form a fixing nip that holds a sheet, a fixing structure (133) that supports the pair of fixing members, a cover (132) attached to the fixing structure, and a transport guide member (70) rotatably assembled to the cover, the cover (132) to which the transport guide member is assembled is fastened to the fixing structure, and the transport guide member is positioned by abutting against the assembled cover from the same direction as the fastening direction. [Selected Figure] Figure 2

Description

The present invention relates to a fixing device and an image forming device.

Conventionally, a fixing device is known that includes a pair of fixing members that form a fixing nip to clamp a sheet, a fixing structure that supports the pair of fixing members, a cover attached to the fixing structure, and a transport guide member rotatably assembled to the cover.
For example, Patent Document 1 describes such a fixing device in which a transport guide member abuts from above against a support area on the upper surface of a side cover attached to both outer sides of a frame (fixing structure) in the longitudinal direction.

It is necessary to improve the positional accuracy of the transport guide member relative to the fixing member supported by the fixing structure.

In order to solve the above-mentioned problems, the present invention provides a fixing device including a pair of fixing members that form a fixing nip that holds a sheet, a fixing structure that supports the pair of fixing members, a cover attached to the fixing structure, and a transport guide member rotatably assembled to the cover, the cover to which the transport guide member is assembled is fastened to the fixing structure, and the transport guide member is positioned by abutting against the assembled cover from the same direction as the fastening direction.

The present invention can improve the positional accuracy of the transport guide member relative to the fixing member supported by the fixing structure.

1 is a diagram showing an outline of an image forming apparatus according to an embodiment of the present invention; FIG. 2 is a cross-sectional view illustrating a fixing device. FIG. 2 is a perspective view illustrating a fixing device. FIG. 6 is an explanatory diagram of a fastening position of the upper cover member. 3A and 3B are schematic diagrams illustrating an example of the configuration of a heating rotator and a pressure roller of a fixing device. FIG. 11 is a cross-sectional view of a fixing device according to a modified example. FIG.

An image forming apparatus that forms an image by an electrophotographic method will be described below as one embodiment of an image forming apparatus to which the present invention is applied.
FIG. 1 is a schematic diagram showing an image forming apparatus according to an embodiment of the present invention.
An image reading device 50 is attached to the upper part of a device main body 40 which is an image forming device.

Inside the device main body 40, a process cartridge 1 is provided. The process cartridge 1 includes a photoconductor 2 as a latent image carrier, and a charging device 3, a developing device 4, and a cleaning device 5, which are arranged around the photoconductor 2 and act on the photoconductor 2 as process means. The process cartridge 1 is detachably mounted in the device main body 40. The photoconductor 2, charging device 3, developing device 4, and cleaning device 5 are unitized as the process cartridge 1, making replacement and maintenance easier. In addition, the positional accuracy between each component can be maintained at a high level, improving the quality of the formed image.

The transfer device, which serves as a transfer means, is equipped with a transfer roller 20, which is pressed against the peripheral surface of the photoreceptor 2. A fixing device 32, which serves as a fixing means, is provided above the transfer device. The fixing device 32 has a heating rotor 60 that performs heating and a pressure roller 62 that serves as a pressure member. The device body 40 is equipped with a laser writing device 30, which serves as a latent image forming means. The laser writing device 30 is equipped with a laser light source, a rotating polygon mirror for scanning, a polygon motor, an fθ lens, and the like. The device body is also equipped with multiple sheet cassettes 11 that store sheets P such as transfer paper and overhead projector films.

When making copies using a device configured as described above, the user presses the start switch. First, the contents of the document set in the image reading device 50 are read. At the same time, the photoreceptor drive motor rotates the photoreceptor 2, and the surface of the photoreceptor 2 is uniformly charged by the charging device 3. Next, a writing process is carried out using the laser writing device 30 by irradiating a laser beam according to the contents of the document read by the image reading device 50. Then, after an electrostatic latent image is formed on the surface of the photoreceptor 2, the developing device 4 is used to attach toner to make the electrostatic latent image visible (developed).

At the same time as the user presses the start switch, the selected sheet P from the multi-stage sheet cassette 11 is sent out by the call roller 11a. Next, the sheets are separated one by one in the separation section 12 and sent to the supply path 13. The sheet P sent to the supply path 13 is stopped by hitting the registration roller 17. Then, in synchronization with the rotation timing of the visualized toner image on the photoconductor 2, the transfer roller 20 is sent into the transfer nip formed by contacting the photoconductor 2.

The toner image on the photoconductor 10 is transferred onto the sheet P sent into the transfer nip by the transfer roller 20. After the image is transferred, the residual toner on the photoconductor 2 is removed and cleaned by the cleaning device 5, and the residual potential on the photoconductor 2 from which the residual toner has been removed is removed by the charger. The sheet is then prepared for the next image formation, which begins with the charging device 3. The residual toner removed by the cleaning device 5 is transported to a waste toner bott.

Meanwhile, the sheet P after the image transfer is guided to the fixing device 32 and passed between a pair of fixing members, a heating rotor 60 and a pressure roller 62, and while being transported between them, heat and pressure are applied to fix the toner image. During single-sided image formation, in which an image is formed on only one side of the sheet P, the sheet P with the fixed image is guided by the branching claw 14 to the paper discharge rollers 33. The paper discharge rollers 33 then discharge the sheet P onto the paper discharge stack section 34 and stack it there.

When forming a double-sided image, the sheet P with the image fixed thereon is guided by the branching claw 14 to the reversing roller 15, which then transports the sheet P to the reversing tray 35 arranged above the discharge stack section 34. Before the trailing end of the sheet P in the transport direction passes the reversing roller 15, the reversing roller 15 is rotated in the reverse direction, and the sheet P is switched back and transported to the resupply path 36, which serves as a reversing transport path. The sheet P transported to the resupply path 36 is transported to the registration roller 17 by multiple transport rollers arranged in the resupply path 36. Then, in the same manner as described above, the sheet is sent to the transfer nip, where the toner image is transferred to the back side, which is the second side of the sheet, and the sheet is discharged onto the discharge stack section 34 via the fixing device 32.

Figure 2 is a cross-sectional view showing the fixing device 32, and Figure 3 is a perspective view showing the fixing device 32. Figure 2(a) shows a state in which a conveying guide plate 70, which serves as a conveying guide member or a rotating member, is in a position during image formation operation, and Figure 2(b) shows a state in which the conveying guide plate 70 has been rotated to a retreated position for jam removal or the like. Figure 3(b) is a partial enlarged view of Figure 3(a). In the following explanation, the vertical direction of the sheet passing through the fixing nip is the X direction, the width direction of the sheet passing through the fixing nip (the axial direction of the heating roller) is the Y direction, and the conveying direction of the sheet passing through the fixing nip (the vertical direction of the device) is the Z direction.

As shown in FIG. 2, the fixing device 32 has a lower cover member 131 and an upper cover member 132, which are resin molded parts that cover the heating rotor 60 and the pressure roller 62. The lower cover member 131 has an entrance section 32a into which the sheet P is introduced after passing through the transfer nip, and the upper cover member 132 has an exit section 32b into which the sheet P with the fixed toner image is discharged. Pressure levers 137 for applying pressure to the pressure roller 62 against the heating rotor 60 penetrate from both ends of the exit section 32b in the Y direction (see FIG. 3).

The upper cover member 132 has a sheet guide portion 136 that guides the sheet moving through the resupply path 36. In the figure, the right wall portion extending downward from the upper wall portion in the figure where the discharge portion 32b is formed via a bent portion constitutes the sheet guide portion 136. The upper cover member 132 of the fixing device 32 is provided with a sheet guide portion 136 that guides the sheet in the resupply path 36. By having the upper cover member 132 of the fixing device double as part of the transport guide for the double-sided path, the resupply path 36 can be located close to the fixing device 32, making it possible to miniaturize the image forming device.

The lower cover member 131 is attached from the -Z direction to a fixing frame 133 made of, for example, sheet metal, which is a fixing structure made of sheet metal. In addition to upper and lower walls perpendicular to the Z direction and left and right walls parallel to the Z direction in FIG. 2, the fixing frame 133 has front and rear end walls perpendicular to the Y direction that are integrated with these end walls, and these end walls support the heating rotor 60 and pressure roller 62.

The upper cover member 132 is attached to the fixing frame 133 to which the lower cover member 131 is attached from the +Z direction. Then, the upper wall portion of the upper cover member 132 perpendicular to the Z direction is fastened to the fixing frame 133 by means of screws 134, which are fastening members. By fastening the upper wall portion of the upper cover member 132 perpendicular to the Z direction to the fixing frame 133 by means of screws 134, the position of the sheet guide portion 136 in the Z direction is determined.

A transport guide plate 70 that assists paper travel so that the paper does not wrap around the pressure roller 62 is rotatably attached to the upper wall of the upper cover member 132. Specifically, in the state shown in FIG. 2(a), the transport guide plate 70 has a base end 70a that extends parallel to the upper wall of the upper cover member 132, and a sheet guide portion 70b that bends and extends from the tip of the base end 70a to enter 32b, and is rotatably attached to the upper cover member 132 at the rear end of the base end 70a. For this assembly, shaft support portions 71 are integrally formed on both ends of the upper cover member 132 in the Y direction as shown in FIG. 3, and the transport guide plate 70 is attached via shafts 72.

At least one of the shaft support parts 71 is provided with a spring 73 that rotates and biases the transport guide plate 70 in the closing direction (see FIG. 3B). If the moment around the shaft due to the weight of the transport guide plate 70 is sufficient to bias the transport guide plate 70 in the closing direction, a biasing member such as a spring can be omitted. A guide plate abutment part 74 against which the base end part 70a of the transport guide plate 70 abuts is integrally formed on the upper wall part of the upper cover member 132. The abutment direction of the transport guide plate 70 against the guide plate abutment part 74 is the same direction as the fastening direction to the fixing frame 133 by the screws 134 on the upper wall part of the upper cover member 132 (parallel to each other or both in the Z direction).

As shown in FIG. 2(b), when a paper jam occurs, the transport guide plate 70 rotates to retract the sheet guide portion 70b from within the discharge portion 32b. This opens the discharge portion 32b widely, making it easier to clear the jam. To facilitate this rotation, the transport guide plate 70 also includes a handle portion 75 for pulling it upward, as shown in FIG. 3(a). The handle portion 75 in the figure is annular.

The sheet guide section 136 is provided with guide ribs 136a. A plurality of guide ribs 136a are arranged at intervals in the Y direction (see FIG. 3(a)). The number of guide ribs 136a and the spacing between the guide ribs 136a can be determined appropriately depending on the device configuration.

As shown in FIG. 2, the fixing frame 133 is made of sheet metal and is susceptible to temperature rise due to the heat of the heating rotor 60. The upper cover member 132 is attached to the fixing frame 133 with a gap d between the fixing frame 133 and the fixing frame 133. In this way, by providing the gap d, it is possible to suppress a rise in temperature of the sheet guide portion 136. In addition, by providing the gap d between the fixing frame 133 and the sheet guide portion 136, it becomes easier to assemble the upper cover member 132 to the fixing frame 133.

A restricting protrusion 135 that restricts deformation of the sheet guide portion 136 is provided on the opposing portion 131a that faces the sheet guide portion 136 of the lower cover member 131. The sheet guide portion 136 abuts against the restricting protrusion 135 of the lower cover member 131, which has positional accuracy in the X direction due to its close contact with the fixing frame 133. A gap d is provided between the sheet guide portion 136 and the fixing frame 133 to prevent warping of the sheet guide portion 136 due to the heat of the heating rotor 60 during operation of the device, which is intended to prevent misalignment in the X direction of the top of the guide rib 136a.

The restricting protrusions 135 are, for example, as shown in FIG. 2, protruding in the Z direction and have a flat tip. A plurality of restricting protrusions 135 are arranged at intervals in the Y direction. The number of restricting protrusions 135 and the arrangement intervals can be determined appropriately depending on the device configuration.

Figure 4 is an explanatory diagram of a preferred fastening position of the screw 134 of the upper cover member 132. In order to achieve high accuracy in the position of the transport guide plate, it is necessary to minimize the effect of the warping of the upper cover member 132. As shown in Figure 4(a), it is preferable to arrange the fastening portion between the upper cover member 132 and the fixing structure between the guide plate abutment portion and the guide plate rotation fulcrum. This makes it possible to make both the guide plate abutment portion 74 and the shaft 72 that serves as the guide plate rotation fulcrum less susceptible to the effect of the warping of the upper cover member 132. If the fastening portion by the screw 134 is arranged outside the guide plate abutment portion 74 and the shaft 72 that serves as the guide plate rotation fulcrum as shown in Figure 4(b), one of them will be farther away from the fastening portion. As a result, the transport guide plate 70 will be lifted due to the influence of the warping of the upper cover member 132, resulting in poor position accuracy, and the possibility of paper entering the gap between the transport guide plate 70 and the pressure roller 62 and causing a paper jam or other problems will increase.

The above embodiment has the following advantages. If the cover is a resin molded product with part of its box shape also serving as the transport path, the natural warping of the shape after molding and the effect of heat from the fixing unit during actual use can cause the warping to worsen or the shape to deform due to heat (reduction in flatness of the surface/deformation). These have an effect on the accuracy of the transport surface. Furthermore, the position of the transport guide plate attached to the cover is also affected by the deformation of the cover.

The fixing device of this embodiment has a fixing member (60) and a pressure member (62) that form a nip portion N that holds the paper, a fixing structure (133) that supports the fixing member and the pressure member, and a cover (132) that forms the outer shell of the fixing device, one side of which also serves as the transport surface (136) of the electrophotographic device. A rotating transport guide plate (70) that is attached to the cover (132) that forms the outer shell of the fixing device is arranged at a predetermined position relative to the pressure member (62) by abutting against the cover (132) that forms the outer shell of the fixing device. The fastening direction between the cover that forms the outer shell of the fixing device and the fixing structure is the same as the abutment direction between the transport guide plate and the cover that forms the outer shell of the fixing device (both are Z directions), and the transport surface of the cover that forms the outer shell of the fixing device is positioned by abutting against a protrusion (135) of another cover (131) without using a fastening member. The target to be abutted may be the fixing structure (133) instead of the protrusion (135) of the other cover (131).

According to this, the position of the conveying guide member is less susceptible to warping and deformation of the cover (132) by making the abutment direction of the cover (132) and the conveying guide member the same direction as the fastening direction between the cover (132) and the fixing structure. Therefore, the positional accuracy of the conveying guide member with respect to the fixing member supported by the fixing structure can be improved. In addition, since the conveying surface of the fixing cover is positioned by abutting against a positioning protrusion (135) provided on the fixing structure or an associated part, the fastening member can be minimized and the number of parts can be reduced while maintaining the position of the perpendicular direction (X) of the conveying surface (136) of the cover (132) with high accuracy. As a result, both the position of the perpendicular direction of the conveying surface of the cover and the position of the rotation direction of the conveying guide plate can be maintained with high accuracy. Since the conveying surface guides the sheet to the desired path, the positional accuracy of the conveying surface perpendicular direction (X), which determines the path, is more important in terms of conveying guide than the direction along the conveying surface (Z). Furthermore, since the transport guide member (70) is attached to the cover (132), assembly is simplified and the cover openings are minimized.

Figure 5 is a schematic diagram of an example of the configuration of the heating rotor 60 and pressure roller 62 of the fixing device 32. The heating rotor 60 is used to fuse and penetrate the transferred toner image T carried on the sheet P by heat and pressure, and is equipped with a fixing belt 61 as an endless heating member that is flexible and can rotate while being heated.

The pressure roller 62 applies pressure to the fixing belt 61 while in contact with the fixing belt 61 to form a nip N. Inside the fixing belt 61, a heater 63 is provided as a heat source consisting of a halogen lamp that heats the area other than the nip N, in this embodiment, the area of the fixing belt 61 that moves around on the opposite side to the nip N.

Inside the fixing belt 61, there are provided a nip forming member 64, which is a base member for forming a nip arranged inside the fixing belt 61, a stay 65 that supports the nip forming member 64, and a reflecting member 66 that reflects light emitted from the heater 63 to the fixing belt 61.

The nip forming member 64 has a flat shape at the nip portion N, but this shape is not limited to this. For example, it may be formed in a concave shape that conforms to the circumferential surface of the pressure roller 62. By making the nip forming member 64 concave to conform to the circumferential surface of the pressure roller 62, the leading edge of the sheet P passing through the nip portion N moves toward the pressure roller 62, improving the separation from the fixing belt 61.

A lubricant such as fluorine grease or silicone oil is applied to the inner surface of the fixing belt 61, and the lubricant is interposed between the nip forming member 64 and the inner surface of the fixing belt 61, reducing the sliding torque.

The temperature of the fixing belt 61 is detected by a temperature sensor 67 provided on the side where the sheet P enters the nip portion, and is used for feedback processing of the heater 63. In FIG. 4, the arrow F indicates the conveying direction of the sheet P.

The fixing belt 61 is a thin, flexible, sleeve-shaped endless belt, and is composed of a base material and a release layer located on its surface. The base material is made of a metal material such as nickel or ASUS, or a resin material such as polyimide. The release layer is made of a tetrafluoroethylene-perfluoroalkylvinylether copolymer (PFA) or polytetrafluoroethylene (PTFE), which has releasability for toner.

The pressure roller 62 is composed of a core 62a, an elastic layer 62b made of foamed silicone rubber, silicone rubber, fluororubber, or the like provided on the surface of the core 62a, and a release layer 62c made of PFA, PTFE, or the like provided on the surface of the elastic layer 62b. The pressure roller 62 is pressed toward the fixing belt 61 by a pressure means and abuts against the fixing belt 61 and the nip forming member 64 via the fixing belt 61 in a state of abutment against the fixing belt 61.

At the point where the pressure roller 62 and the fixing belt 61 come into contact, the elastic layer 62b of the pressure roller 62 is crushed, so that the nip forming member 64 receives pressure between the pressure roller 62 and the fixing belt 61, and a nip portion N of a predetermined width is secured.

The pressure roller 62 is configured to be rotated by a driving source such as a motor provided in the device body 40. When the pressure roller 62 is rotated, the driving force is transmitted to the fixing belt 61 at the nip portion N, so that the fixing belt 61 rotates.

In this configuration example, the pressure roller 62 is a solid roller, but it may be a hollow roller. In that case, a heat source such as a halogen heater that uses radiant heat may be disposed inside the pressure roller 62. Even if the pressure roller 62 is a hollow roller, it is preferable to provide an elastic layer with a thickness of 100 μm or more. This is because eliminating the elastic layer reduces the heat capacity of the pressure roller 62 and improves fixability, but when unfixed toner is crushed and fixed, minute irregularities on the belt surface may be transferred to the image, causing uneven gloss in solid parts of the image. For this reason, it is preferable to provide an elastic layer with a thickness of 100 μm or more.

Aluminum, iron, stainless steel, etc. can be selected as the pipe-shaped metal used for the hollow roller. When a heat source is provided inside the pressure roller 62, it is preferable to provide a heat insulating layer on the surface of the support or provide a heat ray reflecting surface by mirror finishing in order to prevent the support from being heated by radiant heat from the heat source. In this case, the heat source is not limited to the halogen heater described above, but an induction heater, resistance heating element, or carbon heater can also be used.

The pressure roller 62, stays 65, etc. are held in a fixing frame 133 made of metal such as sheet metal. Since the fixing frame 133 has higher rigidity than resin, holding the pressure roller 62 and stays 65 in the fixing frame 133 can improve the positional accuracy of the parts.

As described above, in this embodiment, the rotational driving force of the pressure roller 62 is transmitted to the fixing belt 61 at the nip portion N, and the fixing belt 61 is rotated accordingly. The pressure roller 62 and the fixing belt 61 are longer by D (15 to 20) mm from the widthwise end of a sheet of the maximum paper passing width that the image forming apparatus can pass through. This allows the driving force to be transmitted well from the pressure roller 62 to the fixing belt 61, and the fixing belt 61 to rotate well, even when a sheet of the maximum paper passing width that the image forming apparatus can pass through is passed through the nip portion N.

Figure 6 is a cross-sectional view of a modified fixing device 230, and Figure 7 is an exploded perspective view of the modified fixing device 230. The modified fixing device 230 includes a heater 231, a reflector 232, a stay 233, a fixing belt 236, a pressure roller 237, and a nip forming member 240. The nip forming member 240 includes a metal supporter 234, a heat equalizing pad 238, and the like.

The fixing belt 236 is an endless belt having a predetermined inner diameter and a width greater than the width of the sheet P. The fixing belt 236 is made of a flexible material and has, for example, a base layer, an elastic layer provided on the outer peripheral surface of the base layer, and a release layer provided on the outer peripheral surface of the elastic layer.

The base layer is made of metal such as SUS or Ni, the elastic layer is made of silicone rubber, and the release layer is made of PFA tubing. Both ends of the fixing belt 236 are rotatably supported by the fixing housing.

A stay 233 is provided at the bottom of the hollow portion of the fixing belt 236. The stay 233 is a channel-shaped (U-shaped cross section) member that is longer than the length of the fixing belt 236 in the width direction X and has an open top, and both ends of the stay 233 are supported by the fixing housing. Three positioning holes 239 are formed in the stay 233 at predetermined intervals in the width direction X. The positioning pins 234b of the metal supporter 234 of the nip forming member 240 fit into these positioning holes 239, and the nip forming member 240 is positioned on the stay 233. The reflector 232 is supported on the upper surface of the stay 233.

The heater 231 (e.g., a halogen heater) has a length equal to the length along the rotation axis of the fixing belt 236. The heater 231 is disposed in the upper part of the hollow part of the fixing belt 236 (above the stay 233), and both ends are supported by the fixing housing.

The heater 231 radiates radiant heat to the inner surface of the fixing belt 236 (mainly a portion slightly narrower than the upper half circumference) to heat the fixing belt 236. The radiant heat radiated from the heater 231 is reflected by the reflector 232 to the inner surface of the fixing belt 236. The heater 231 is controlled by the control unit.

The pressure roller 237 has a core, an elastic layer provided on the outer peripheral surface of the core, and a release layer provided on the outer peripheral surface of the elastic layer. The elastic layer is made of silicone rubber or the like. The release layer is made of a PFA tube or the like.

The pressure roller 237 is disposed opposite the fixing belt 236 and supported by the fixing housing. The pressure roller 237 contacts the outer peripheral surface of the fixing belt 236 to form a nip portion N between the pressure roller 237 and the fixing belt 236. The pressure roller 237 is connected to a motor controlled by the control unit, for example, and driven to rotate. When the pressure roller 237 rotates in the clockwise direction in FIG. 6, the fixing belt 236 rotates counterclockwise, driven by the pressure roller 237, opposite the rotation direction of the pressure roller 237. As a result, the sheet P passes through the nip portion N.

The metal supporter 234 of the nip forming member 240 is a flat, roughly rectangular parallelepiped member that is elongated in the width direction X of the fixing belt 236, and is made of, for example, a metal material. On the surface of the metal supporter 234 facing the stay 233, multiple (18) protrusions 234a, multiple (7) fixing pins 234c, and multiple (3) positioning pins 234b are erected at predetermined positions.

The heat equalizing pad 238 is a sheet-like member with a width equal to that of the metal supporter 234 and a length that allows it to be wrapped around the metal supporter 234 once. As an example, it is formed by weaving PTFE fibers and PPS fibers.

The heat equalizing pad 238 is wrapped around the metal supporter 234 once so that both ends are located at the center of the surface of the metal supporter 234 facing the stay 233 in the sheet conveying direction. At the point where the heat equalizing pad 238 is wrapped around the surface facing the stay 233, a through hole 238a is provided through which the protrusion 234a of the metal supporter 234 passes. As shown in FIG. 7, the heat equalizing pad 238 is also provided with a fixing hole 238b into which the fixing pin 234c formed by combining both ends fits, and a positioning hole 238c into which the positioning pin 234b fits.

The heat equalizing pad 238 may be impregnated with a lubricant (oil, grease). The heat equalizing pad 238 may be used to apply the lubricant to the inner surface of the fixing belt 236.

The fixing device 32 of this modified configuration can fix the toner image onto the sheet P by the same operation as the fixing device of the present embodiment shown in FIG. 5.

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to the specific embodiment, and various modifications and variations are possible within the scope of the spirit of the present invention described in the claims unless otherwise specifically limited in the above description. The effects described in the embodiment of the present invention are merely a list of the most preferable effects resulting from the present invention, and the effects of the present invention are not limited to those described in the embodiment of the present invention.

The above description is merely an example, and the present invention provides unique effects for each of the following aspects.
(Aspect 1)
In a fixing device including a pair of fixing members (60, 62) that form a fixing nip that holds a sheet, a fixing structure (133) that supports the pair of fixing members, a cover (132) attached to the fixing structure, and a transport guide member (70) rotatably assembled to the cover, the cover (132) to which the transport guide member is assembled is fastened to the fixing structure, and the transport guide member is positioned by abutting against the assembled cover from the same direction as the fastening direction. This makes it possible to improve the positional accuracy of the transport guide member relative to the fixing members and the like supported by the fixing structure, as described in the embodiment.

(Aspect 2)
In the fixing device described in (Aspect 1), the attached cover (132) has a transport surface portion (136) having a transport surface, and the transport surface portion is positioned by abutting against the fixing structure (133) or another cover (131) attached to the fixing structure without using a fastening member. This makes it possible to minimize the fastening members and reduce the number of parts, as described in the embodiment, while maintaining both the position of the transport surface (136) of the cover (132) in the perpendicular direction (X) and the position of the transport guide member (70) in the rotation direction with high accuracy.

(Aspect 3)
In the fixing device described in (Aspect 2), the conveying surface portion is a surface portion extending from the fastening or abutting surface portion via a bent portion. With this, the positional accuracy of the surface portion extending from the fastening or abutting surface portion via a bent portion in the perpendicular direction to the conveying surface can be maintained. In many devices, the bent portion is bent at a 90° angle, but the angle is not limited to 90°.

(Aspect 4)
In the fixing device described in (Aspect 2 or 3), the location where the conveying surface is abutted and positioned is a location on the opposite side of the bent portion in the extending direction of the conveying surface. The opposite side means a location closer to the end than the midpoint between the end on the opposite side of the bent portion in the extending direction and the bent portion. However, a certain degree of effect can also be obtained at a location closer to the bent portion than the midpoint, and such an embodiment is also included in Aspect 2 or 3.

(Aspect 5)
In the fixing device described in (Aspects 1 to 4), the fastening point of the assembled cover (132) is between the rotation center of the transport guide member and the point where the transport guide member abuts. This makes it possible to make both the guide plate abutment portion (74) and the shaft (72) that serves as the guide plate rotation fulcrum less susceptible to the effects of warping of the assembled cover (132), as described in the embodiment. However, even if the fastening point is on the opposite side of the rotation center from the point where the transport guide member abuts, a certain degree of effect can be obtained, and aspects 1 to 4 also include such aspects.

(Aspect 6)
In the fixing device described in (Aspects 1 to 5), the transport guide member is a member that guides a sheet discharged from the fixing nip. This makes it possible to maintain the accuracy of the rotation position of the transport guide member while preparing for removal of jammed paper from the discharge section 32b as described in the embodiment. The transport guide member is not limited to a member that guides a sheet discharged from the fixing nip, but may be a member that guides a sheet entering the fixing nip, and Aspects 1 to 4 include such aspects.

(Aspect 7)
In the fixing device described in (Aspects 1 to 6), at least one of the pair of fixing members is a member that heats the sheet. This makes it possible to prevent deterioration of the accuracy of the rotation position of the transport guide member due to deformation of the cover caused by heat. However, the present invention can also be applied to a fixing device in which neither of the pair of fixing members has a heating function and fixes the image by a physical force other than heat, such as pressure alone, and Aspects 1 to 6 also include such aspects.

(Aspect 8)
In the fixing device described in (Aspect 1), the assembled cover (132) forms an outer shell of the fixing device. With this, even if an external force is applied to the outer shell from the outside, the positional accuracy of the conveying guide member in the moving direction can be maintained.

(Aspect 9)
The fixing device includes a pair of fixing members that form a fixing nip that holds a sheet, a fixing structure that supports the pair of fixing members, a cover (132) attached to the fixing structure, and a rotatable rotating member, the cover (132) is fastened to the fixing structure, and the rotating member is positioned by abutting against the cover (132) from the same direction as the fastening direction. In aspects 1 to 8, the attachment target of the transport guide member corresponding to the rotating member is a cover attached to the fixing structure, but this is not limited thereto, and for example, the attachment target may be the fixing structure, and the positioning in the rotation direction may be performed by the cover. In this case, the positional accuracy of the rotating member in the rotation direction can be maintained. In aspects 1 to 8, the rotating member is a transport guide member, but this is not limited thereto, and it may be another functional member.

1: Process cartridge 2: Photoconductor 3: Charging device 4: Development device 5: Cleaning device 10: Photoconductor 11: Sheet cassette 11a: Call roller 12: Separation section 13: Supply path 14: Branching claw 15: Reversing roller 17: Registration roller 20: Transfer roller 30: Laser writing device 32: Fixing device 32a: Carry-in section 32b: Discharge section 33: Discharge roller 34: Discharge stack section 35: Reversing tray 36: Resupply path 40: Apparatus main body 50: Image reading device 60: Heating rotor 61: Fixing belt 62: Pressure roller 62a: Core metal 62b: Elastic layer 62c: Release layer 63: Heater 64: Nip forming member 65: Stay 66: Reflecting member 67: Temperature sensor 70: Transport guide plate 70a: Base end 70b : sheet guide portion 71 : shaft support portion 72 : shaft 73 : spring 74 : guide plate abutment portion 75 : handle portion 131 : lower cover member 131a : facing portion 132 : upper cover member 133 : fixing frame 134 : screw 135 : regulating projection 136 : sheet guide portion 136a : guide rib 137 : pressure lever 230 : fixing device 231 : heater 232 : reflector 233 : stay 234 : metal supporter 234a : projection 234b : positioning pin 234c : fixing pin 236 : fixing belt 237 : pressure roller 238 : heat equalizing pad 238a : through hole 238b : fixing hole 238c : positioning hole 239 : positioning hole 240 : nip forming member N : nip portion P : sheet T : toner image X : width direction d : gap

JP 2016-90661 A

Claims (10)

A pair of fixing members that form a fixing nip that holds a sheet;
a fixing structure supporting the pair of fixing members;
a cover attached to the fixing structure;
A fixing device including a conveying guide member rotatably attached to the cover,
a cover to which the transport guide member is attached is fastened to the fixing structure,
The fixing device according to claim 1, wherein the transport guide member is positioned by being abutted against the assembled cover in the same direction as the fastening direction. 2. The fixing device according to claim 1,
the assembled cover has a conveying surface portion with a conveying surface;
The fixing device according to claim 1, wherein the conveying surface portion is positioned by abutting against the fixing structure or another cover attached to the fixing structure without using a fastening member. 3. The fixing device according to claim 2,
The fixing device, wherein the transport surface portion is a surface portion extending from the fastening or abutting surface portion via a bent portion. 4. The fixing device according to claim 3,
The fixing device, wherein the abutting and positioning portion of the transport surface portion is a portion on an opposite side of the bent portion in an extending direction of the transport surface portion. 2. The fixing device according to claim 1,
a fixing device, wherein a fastening point of the assembled cover is between a rotation center of the transport guide member and a point where the transport guide member abuts against the rotation center; 2. The fixing device according to claim 1,
The fixing device, wherein the transport guide member is a member that guides a sheet discharged from the fixing nip. 2. The fixing device according to claim 1,
4. A fixing device, comprising: a fixing member for fixing a sheet; 2. The fixing device according to claim 1,
The fixing device, wherein the assembled cover forms an outer shell of the fixing device. A pair of fixing members that form a fixing nip that holds a sheet;
a fixing structure supporting the pair of fixing members;
a cover attached to the fixing structure;
A fixing device including a rotatable member,
The cover is fastened to the fixing structure,
The fixing device according to claim 1, wherein the rotating member is positioned by being brought into contact with the cover in the same direction as the fastening direction. In an image forming apparatus having a fixing device for fixing a toner image carried on a sheet onto the sheet,
10. An image forming apparatus comprising the fixing device according to claim 1 as the fixing device.

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