Sheet conveying device, fixing device, and image forming apparatus

Abstract

To provide a conveying device capable of reducing the variation in a distance between axes of two gears for driving a conveying roller capable of releasing a nip.SOLUTION: A fixing device 1 according to the present invention comprises a main body, a conveying roller, a second guide 12, a roller gear 13 and a drive gear 14. The main body has a first guide. The second guide 12 faces the first guide and holds the conveying roller. The second guide 12 is rotatable between a first position and a second position. The roller gear 13 is coaxially mounted with the conveying roller. The drive gear 14 meshes with the roller gear 13 when the second guide 12 is positioned at the first position. The main body has a first arc surface 15A coaxial with the drive gear 14. The second guide 12 has a second arc surface 12A coaxial with the roller gear 13. When the second guide 12 is positioned at the first position, the first arc surface 15A and the second arc surface 12A come into contact with each other.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a sheet conveying device, a fixing device, and an image forming apparatus. [Background technology]

[0002] 2. Description of the Related Art Conventionally, there is known a fixing device that can release the nip of a conveying roller that conveys a sheet discharged from between a heating member and a pressure member in order to clear a jam (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-124692 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when a gear provided at the end of one of a pair of conveying rollers meshes with a gear provided at the end of the other roller and a driving force is input to one of the gears to rotate the conveying roller, if the distance between the axes of the two gears is not constant, the rotation of the conveying roller may become unstable.In a sheet conveying device capable of releasing the nip, the position of one of the rollers can be moved, which poses a problem in that the distance between the axes of the two gears used to drive the conveying roller is easily inaccurate.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a conveying device that can reduce variations in the distance between the axes of two gears that drive a conveying roller that can release the nip. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, a sheet transporting device according to the present invention includes a main body, a transport roller, a second guide, a roller gear, and a drive gear. The main body has a first guide that guides one surface of the sheet. The transport roller rotates in contact with the other surface of the sheet. The second guide guides the other side of the sheet. The second guide faces the first guide and rotatably holds the conveying roller. The second guide is rotatable between a first position and a second position around a first rotation axis that is spaced apart from the conveying roller. The roller gear is provided coaxially with the conveying roller. The drive gear is held by the main body and rotates by receiving a driving force from a drive source. The drive gear meshes with the roller gear when the second guide is located in the first position, and disengages from the roller gear when the second guide is located in the second position. The body has a first arcuate surface coaxial with the drive gear. The second guide has a second arcuate surface coaxial with the roller gear. When the second guide is located at the first position, the first arcuate surface and the second arcuate surface come into contact with each other.

[0007] When the second guide is located at the first position, the first arcuate surface and the second arcuate surface come into contact with each other, so that the variation in the center distance between the drive gear and the roller gear can be reduced.

[0008] The main body may further include a gear plate to which a shaft that rotatably holds the drive gear is fixed, and a gear cover that is fixed to the gear plate and covers the drive gear from the side opposite to the gear plate. The first arc surface may be provided on the gear cover.

[0009] Since the drive gear and the first arcuate surface are both held by the gear plate, it is easy to make the first arcuate surface coaxial with the drive gear.

[0010] The first guide may be provided with a pinch roller that comes into contact with the conveying roller and conveys the sheet between the first guide and the conveying roller.

[0011] The second guide may have an engagement portion that engages with the body to hold the second guide in the first position.

[0012] The engaging portion may be a lever that is rotatable about the second rotation axis between a locked position where it engages with the main body and an unlocked position where it is disengaged from the main body.

[0013] The fixing device according to the present invention, which solves the above-mentioned problems, includes a heating member, a pressure member, a main body, a conveying roller, a second guide, a roller gear, and a drive gear. The heating element heats the sheet. The pressure member nips the sheet between itself and the heating member. The main body has a first guide that guides one surface of the sheet discharged from between the heating member and the pressure member. The transport roller rotates in contact with the other surface of the sheet. The second guide guides the other side of the sheet. The second guide faces the first guide and rotatably holds the conveying roller. The second guide is rotatable between a first position and a second position around a first rotation axis that is spaced apart from the conveying roller. The roller gear is provided coaxially with the conveying roller. The drive gear is held by the main body and rotates by receiving a driving force from a drive source. The drive gear meshes with the roller gear when the second guide is located in the first position, and disengages from the roller gear when the second guide is located in the second position. The body has a first arcuate surface coaxial with the drive gear. The second guide has a second arcuate surface coaxial with the roller gear. When the second guide is located at the first position, the first arcuate surface and the second arcuate surface come into contact with each other.

[0014] In the fixing device, when the second guide is located at the first position, the first arcuate surface and the second arcuate surface come into contact with each other, so that the variation in the center distance between the drive gear and the roller gear can be reduced.

[0015] The image forming apparatus may include a main body housing and the fixing device described above. The fixing device is detachable from the main body housing. [Effects of the Invention]

[0016] According to the present invention, it is possible to reduce variations in the distance between the axes of two gears for driving a conveying roller capable of releasing a nip. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 2 is a cross-sectional view of the fixing device according to the embodiment. [Figure 2] 4 is a cross-sectional view of the fixing device according to the embodiment, showing a state in which the nip pressure between the heating roller and the pressure roller is reduced. FIG. [Figure 3] FIG. 2 is a perspective view of a fixing frame of the fixing device according to the embodiment. [Figure 4] 1 is a perspective view of the fixing device according to the embodiment, seen from the upstream side in the mounting direction, showing a state in which the second guide is located at a first position. [Figure 5] 10 is a perspective view of the fixing device according to the embodiment, seen from the upstream side in the mounting direction, showing a state in which the second guide is located at a second position. FIG. [Figure 6] 3 is a side view of the fixing device according to the embodiment, showing a first arcuate surface and a second arcuate surface. FIG. [Figure 7] FIG. 2 is a perspective view of the fixing device according to the embodiment, seen from the upstream side in the installation direction. [Figure 8] FIG. 2 is a diagram illustrating a state in which the fixing device is attached to the main body housing of the image forming apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0018] Next, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. As shown in Fig. 1, a fixing device 1, which is an example of a sheet conveying device, is a device that fixes a toner image on a sheet S. The fixing device 1 can be attached to a main body housing MB (see Fig. 8) of an image forming apparatus PR such as a printer. The fixing device 1 includes a heating roller 2, which is an example of a heating member, a pressure roller 3, which is an example of a pressure member, a fixing frame 4, an arm 5, a spring 6, and a cam 7.

[0019] The heating roller 2 extends in the longitudinal direction and rotates around a rotation axis X (see FIG. 3). The heating roller 2 rotates by receiving a driving force from a motor (not shown) provided in the image forming apparatus PR. The heating roller 2 has a roller 2A and a heater H. In this embodiment, the heating roller 2 has two heaters H1 and H2. The roller 2A is a metal tube and is heated by the heater H. The heater H is disposed inside the roller 2A. The heater H is, for example, a halogen heater.

[0020] In the following description, the longitudinal direction of the heating roller 2 will be simply referred to as the longitudinal direction. The longitudinal direction is also the direction of the rotation axis X of the heating roller 2. The arrow indicating the longitudinal direction in the drawings points to one side in the longitudinal direction, and the direction opposite to the arrow points to the other side in the longitudinal direction. The direction in which the fixing device 1 is attached to the main body housing MB will be referred to as the attachment direction. The fixing device 1 is attached by moving from the rear to the front of the main body MB. The front-to-rear and up-to-down directions of the fixing device 1 are the front-to-rear and up-to-down directions of the main body housing MB when the fixing device 1 is attached to the main body housing MB. The sheet S is transported from the front to the rear of the fixing device 1 and passes through the fixing device 1. After passing through the fixing device 1, the sheet S is transported upward of the fixing device 1.

[0021] The pressure roller 3 extends in the longitudinal direction (see FIG. 3). The pressure roller 3 rotates following the rotation of the heat roller 2, and nips the sheet S between the pressure roller 3 and the heat roller 2. The pressure roller 3 has a shaft 3A and a roller body 3B. The shaft 3A is made of, for example, metal. The roller body 3B is made of, for example, rubber, and is provided so as to cover the periphery of the shaft 3A.

[0022] 3, the fixing frame 4 includes a pair of side frames 4A and 4B and a connecting frame 4C. The side frames 4A and 4B are located at both ends of the heating roller 2 and the pressure roller 3 in the longitudinal direction. The side frames 4A and 4B rotatably support the heating roller 2. The side frame 4A is an example of a gear plate. The connecting frame 4C is a metal plate that extends in the longitudinal direction and connects the side frame 4A on one side in the longitudinal direction to the side frame 4B on the other side in the longitudinal direction. The cam 7 includes a cam 7A and a cam 7B. The cam 7A is located close to the side frame 4A. The cam 7B is located close to the side frame 4B. The cams 7A and 7B are connected by a camshaft 8. The camshaft 8 is rotatably supported by the side frames 4A and 4B.

[0023] 1 and 2, the arm 5, spring 6, and cam 7 constitute a pressure change mechanism that changes the nip pressure between the heating roller 2 and the pressure roller 3. The pressure change mechanism can change the nip pressure by moving at least one of the heating roller 2 and the pressure roller 3 relative to the other. In this embodiment, the pressure change mechanism changes the nip pressure by moving the pressure roller 3 relative to the heating roller 2.

[0024] The arm 5 has one end 5A, the other end 5B, a first portion 5C, and a second portion 5D. The arm 5 is rotatable about an arm axis 1X extending in the longitudinal direction.

[0025] One end 5A is rotatably supported by the side frame 4B on the other side in the longitudinal direction via a shaft 5E. The other end 5B has a cam follower 5F. The cam follower 5F is capable of coming into contact with the cam 7.

[0026] The first portion 5C and the second portion 5D are located between the one end 5A and the other end 5B. The first portion 5C supports the pressure roller 3. The second portion 5D is a portion to which a spring 6 is connected. One end of the spring 6 is hooked to the second portion 5D, and the other end of the spring 6 is hooked to the side frame 4A. The spring 6 presses the pressure roller 3 against the heating roller 2 via the arm 5.

[0027] The cam 7B is rotatably supported by the side frame 4B on the other side in the longitudinal direction via a camshaft 8, and is rotatable around a cam shaft 2X extending in the longitudinal direction. The cam 7B moves the pressure roller 3 by rotating, thereby changing the nip pressure that nips the sheet S. The cam 7B is rotatable between a first position shown in FIG. 1 and a second position shown in FIG. 2.

[0028] The first position is a position where the nip pressure is a first nip pressure. The second position is a position where the nip pressure is a second nip pressure that is lower than the first nip pressure. Cam 7B can rotate clockwise from the first position shown in FIG. 1 to the second position shown in FIG. 2.

[0029] The arm 5, spring 6 and cam 7A provided on the side frame 4A on one side in the longitudinal direction have a configuration symmetrical to the arm 5, spring 6 and cam 7B provided on the side frame 4B on the other side in the longitudinal direction, so detailed explanation will be omitted.

[0030] 3, the fixing device 1 further includes a cam gear 9 and a fixing gear 10. The cam gear 9 is fixed to the end of the camshaft 8. The cam gear 9 is connected to the cam 7 via the camshaft 8 and transmits a driving force to the cam 7. The cam gear 9 is located on one side in the longitudinal direction with respect to the longitudinal center CL of the heating roller 2. The cam gear 9 has a plurality of gear teeth 9A and a flange 9B extending from near the base of the gear teeth 9A to one side in the longitudinal direction. The flange 9B has a notch 9C for detecting the phase of the cam 7.

[0031] The fixing gear 10 has a plurality of gear teeth 10A. The fixing gear 10 is fixed to an end of the roller 2A in the longitudinal direction. The fixing gear 10 is provided coaxially with the heating roller 2. The fixing gear 10 transmits driving force to the heating roller 2.

[0032] Returning to FIG. 1, the fixing device 1 further includes a first guide 11, a second guide 12, a pair of handles 16, a conveying roller R2, and two pinch rollers R1. The first guide 11 and the second guide 12 are members that guide the sheet S discharged from between the heating roller 2 and the pressure roller 3. The first guide 11 guides one side of the sheet S. In this embodiment, the first guide 11 guides the upper surface of the sheet S. The first guide 11 is fixed to the connection frame 4C of the fixing frame 4. The first guide 11 has a guide rib 11A. The guide rib 11A contacts the sheet S to guide it. The two pinch rollers R1 are supported by the first guide 11 so as to be rotatable and movable up and down. The pinch roller R1 contacts the conveying roller R2 and conveys the sheet S between the pinch roller R1 and the conveying roller R2.

[0033] The second guide 12 faces the first guide 11 and guides the other side of the seat S. In this embodiment, the second guide 12 guides the underside of the seat S. The second guide 12 is located at the lower end of the second guide 12 relative to the first guide 11 and is rotatable around a first rotation shaft 3X extending in the longitudinal direction. More specifically, as shown in FIG. 4, the second guide 12 has a protrusion 12B at its lower end that protrudes outward in the longitudinal direction. As shown in FIG. 5, one handle 16 is fixed to the side frame 4A, and the other handle 16 is fixed to the side frame 4B. Each handle 16 has a shaft support hole 16A (only one is shown). The protrusion 12B is inserted into the shaft support hole 16A, thereby supporting the second guide 12 by the handle 16 so that the second guide 12 is rotatable around the first rotation shaft 3X.

[0034] The second guide 12 holds a conveying roller R2 (see FIG. 4) extending in the longitudinal direction so that it can rotate about a fifth axis 5X. The conveying roller R2 has a shaft 18A and two rollers 18B provided on the shaft 18A. The second guide 12 is rotatable about a first rotation axis 3X between a first position shown in FIG. 4 and a second position shown in FIG. 5. When the second guide 12 is located at the first position, the roller 18B of the conveying roller R2 comes into contact with the pinch roller R1. The conveying roller R2 rotates in contact with the other side of the sheet S to convey the sheet S. The conveying roller R2 and the pinch roller R1 convey the sheet S discharged from between the heating roller 2 and the pressure roller 3.

[0035] As shown in FIG. 5, the fixing device 1 further includes a roller gear 13, a drive gear 14, an idle gear 21 (see FIG. 6), a gear cover 15, and an exterior cover 22 (see FIG. 7). The roller gear 13 is provided at one end of the shaft 18A of the conveying roller R2 in the longitudinal direction. The roller gear 13 is rotatable about a fifth axis 5X extending in the longitudinal direction. In other words, the roller gear 13 is provided coaxially with the conveying roller R2.

[0036] The drive gear 14 is rotatably held on a shaft 19 fixed to the side frame 4A. The drive gear 14 is rotatable around a sixth axis 6X extending in the longitudinal direction. The drive gear 14 meshes with the roller gear 13 when the second guide 12 is located in the first position, and disengages from the roller gear 13 when the second guide 12 is located in the second position.

[0037] The idle gear 21 is rotatably supported by the side frame 4 A. The idle gear 21 is in mesh with the fixing gear 10 and the drive gear 14.

[0038] The idle gear 21 rotates by receiving a driving force from the fixing gear 10. The drive gear 14 rotates by receiving a driving force from the idle gear 21. The roller gear 13 receives a driving force from the drive gear 14 and transmits the driving force to the conveying roller R2, causing the conveying roller R2 to rotate.

[0039] The gear cover 15 covers the drive gear 14 from the side opposite to the side frame 4A. The gear cover 15 is fixed to the side frame 4A. The gear cover 15 has a first arcuate surface 15A that is coaxial with the drive gear 14. That is, the first arcuate surface 15A has an arcuate shape centered on the sixth axis 6X.

[0040] The second guide 12 has a second arcuate surface 12A that is coaxial with the roller gear 13. That is, the second arcuate surface 12A has an arcuate shape centered on the fifth axis 5X. As shown in Fig. 6, when the second guide 12 is located at the first position, the second arcuate surface 12A comes into contact with the first arcuate surface 15A.

[0041] 7, the exterior cover 22 is a cover that covers the fixing device 1. The exterior cover 22 covers the fixing frame 4, the cam 7, the camshaft 8, the cam gear 9, and the fixing gear 10. Specifically, the exterior cover 22 covers the side surface of the cam 7A facing the cam shaft 2X and a portion of the first cam surface 71A. The exterior cover 22 also covers a portion of the gear teeth 9A of the cam gear 9 and a portion of the gear teeth 10A of the fixing gear 10. The exterior cover 22 has a first opening 22A, a second opening 22B, and a third opening 22C on one side in the longitudinal direction. The first opening 22A exposes a portion of the first cam surface 71A of the cam 7A. The second opening 11B exposes a portion of the gear teeth 9A of the cam gear 9. The second opening 22B opens toward the downstream side and upward in the mounting direction. A portion of the cam gear 9 protrudes from the second opening 22B to the outside of the exterior cover 22. The third opening 22C is located downstream of the second opening 22B in the mounting direction. The third opening 22C exposes a portion of the gear teeth 10A of the fixing gear 10. The third opening 22C opens toward the downstream side and upward in the mounting direction. A portion of the fixing gear 10 protrudes from the third opening 22C to the outside of the exterior cover 22.

[0042] As shown in FIG. 6 , the second guide 12 has a lever LV. The lever LV has a torsion coil spring SP. The lever LV is rotatable around a second rotation axis 4X extending in the longitudinal direction between a locked position where it engages with the engagement portion 22A of the exterior cover 22 and an unlocked position where it disengages from the engagement portion 22A. The unlocked position is a position where the lever LV is rotated counterclockwise from the locked position. The lever LV is biased by the torsion coil spring SP in a direction from the unlocked position to the locked position. When the second guide 12 is located in the first position, the lever LV engages with the exterior cover 22 and holds the second guide 12 in the first position. When the lever LV is engaged with the exterior cover 22, the lever LV biases the second guide 12 in a direction to close it. This presses the second arcuate surface 12A against the first arcuate surface 15A, maintaining contact between the second arcuate surface 12A and the first arcuate surface 15A.

[0043] As shown in FIG. 8, the image forming apparatus PR includes a main body housing MB and a fixing device 1. The main body housing MB includes a fixing drive gear 91 that transmits driving force to a fixing gear 10 to drive the heating roller 2, a cam drive gear 92 that transmits driving force to a cam gear 9 to drive the cam 7, and a cover CR. The fixing drive gear 91 and the cam drive gear 92 are driven by a motor (not shown). The cover CR can open and close an opening on one side of the main body housing MB at the rear. An image forming unit 100 that forms a toner image on a sheet S is provided within the main body housing MB. The image forming unit 100 supplies the sheet S on which the toner image has been formed to the fixing device 1.

[0044] When the fixing device 1 is to be attached to the main body housing MB of the image forming apparatus PR, the cover CR on the side of the main body housing MB is opened, and the fixing device 1 is inserted into the main body housing MB in the attachment direction. Then, the cam gear 9 meshes with the cam drive gear 92. Also, the fixing gear 10 meshes with the fixing drive gear 91.

[0045] As described above, the following effects can be obtained in this embodiment.

[0046] When the second guide 12 is located at the first position, the first arcuate surface 15A and the second arcuate surface 12A come into contact with each other, so that the variation in the center distance between the drive gear 14 and the roller gear 13 can be reduced.

[0047] Since both the drive gear 14 and the first arcuate surface 15A are held by the side frame 4A, the first arcuate surface 15A can be easily made coaxial with the drive gear 14.

[0048] The present invention is not limited to the above-described embodiment, but can be used in various forms as exemplified below.

[0049] In the above-described embodiment, the lever LV provided on the second guide 12 is exemplified as the engaging portion, but the engaging portion may be any portion that holds the second guide in the first position. For example, the engaging portion may be provided on the main body side of the first guide 11 or the like, and may be, for example, a protrusion or a hook.

[0050] The elements described in the above-described embodiment and modified examples may be implemented in any combination. [Explanation of symbols]

[0051] 3X 1st rotating axis 11 First Guide 12 Second Guide 12A Second arc surface 13 Roller gear 14 Drive gear 15A First circular arc surface R2 transport roller

Claims

1. a main body having a first guide for guiding one surface of the sheet; a conveying roller that rotates in contact with the other surface of the sheet; a second guide that guides the other surface of the sheet, the second guide facing the first guide, the second guide rotatably holding the conveying roller, and the second guide being rotatable between a first position and a second position around a first rotation axis that is spaced apart from the conveying roller; a roller gear provided coaxially with the conveying roller; a drive gear that is held by the main body and rotates by receiving a drive force from a drive source, the drive gear meshing with the roller gear when the second guide is located at the first position and disengaging from the roller gear when the second guide is located at the second position, the main body has a first arcuate surface coaxial with the drive gear; the second guide has a second arcuate surface coaxial with the roller gear, The sheet conveying device, wherein the first arcuate surface and the second arcuate surface come into contact with each other when the second guide is located at the first position.

2. The body includes: a gear plate to which a shaft that rotatably holds the drive gear is fixed; a gear cover fixed to the gear plate and covering the drive gear from the side opposite to the gear plate, 2. The sheet transport device according to claim 1, wherein the first arcuate surface is provided on a gear cover.

3. 2. The sheet transport device according to claim 1, wherein the first guide is provided with a pinch roller that contacts the transport roller and transports the sheet between the first guide and the transport roller.

4. 2. The sheet transport device according to claim 1, wherein the second guide has an engaging portion that engages with the main body to hold the second guide at the first position.

5. 5. The sheet conveying device according to claim 4, wherein the engaging portion is a lever and is rotatable around a second pivot axis between a locked position in which it engages with the main body and an unlocked position in which it disengages from the main body.

6. a heating element for heating the sheet; a pressure member that nips the sheet between itself and the heating member; a main body having a first guide that guides one surface of the sheet discharged from between the heating member and the pressure member; a conveying roller that rotates in contact with the other surface of the sheet; a second guide that guides the other surface of the sheet, the second guide facing the first guide, the second guide rotatably holding the conveying roller, and the second guide being rotatable between a first position and a second position around a first rotation axis that is spaced apart from the conveying roller; a roller gear provided coaxially with the conveying roller; a drive gear held by the main body and rotated by receiving a drive force from a drive source, the drive gear meshing with the roller gear when the second guide is located at the first position and disengaging from the roller gear when the second guide is located at the second position; Equipped with the main body has a first arcuate surface coaxial with the drive gear; the second guide has a second arcuate surface coaxial with the roller gear, The fixing device, wherein the first arcuate surface and the second arcuate surface are in contact with each other when the second guide is located at the first position.

7. A main body housing; The fixing device according to claim 6, The image forming apparatus is characterized in that the fixing device is detachable from the main body housing.

Images