Belt device, fixing device, and image forming apparatus

Abstract

To provide a belt device that can release the tension of a belt through operations to take out the belt for every support roller.SOLUTION: A belt device comprises: a belt 94; support rollers 91, 93, 96 that support the belt; a tension member 95 that is in contact with the belt; and pressure mechanisms 923, 925 that press the tension member against the belt. A first unit 910 including the support rollers and the belt is detachably attached to a device main body 930. A second unit including the tension member and the pressure mechanisms is provided on the first unit movably between an actuation position for applying tension to the belt and a release position where the tension is released. The device main body is provided with a positioning part 933 that positions the second unit at the actuation position and releases the positioning to the actuation position through the attachment and detachment movement of the first unit relative to the device main body.SELECTED DRAWING: Figure 5

Description

[Technical Field]

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

[0002] Conventionally, a belt device has been known that includes a belt, multiple support rollers that support the belt, a contact member that contacts the belt, and a pressing mechanism that presses the contact member against the belt. For example, Patent Document 1 describes a belt conveying device that includes an endless belt suspended between a drive roller and a tension roller, a support member that rotatably supports the tension roller, and a belt tensioning means that includes a biasing member that biases the support member in a direction that applies tension to the endless belt. In this belt device, when the belt tensioning means is attached, the belt tensioning means can swing around the rotation axis of the tension roller against the biasing force of the biasing member and has an engaging portion that engages and holds the engaged portion of the belt tensioning means at a predetermined position. This allows for easy assembly and removal of the belt tensioning means without the use of dedicated tools. Summary of the Invention [Problem to be solved by the invention]

[0003] However, when removing the belt, the belt must be removed together with the support roller, and when removing the belt from the support roller and releasing the tension to replace the belt, the work of removing the belt together with the support roller and the work of removing the belt tension applying means must be performed separately, which requires a lot of work.Furthermore, when installing the belt, the work of installing the belt tension applying means and the work of installing the belt together with the support roller must be performed separately, which requires a lot of work. [Means for solving the problem]

[0004] In order to solve the above-mentioned problems, the present invention provides a belt device comprising a belt, a support roller that supports the belt, a tension member that contacts the belt, and a pressing mechanism that presses the tension member against the belt, wherein a first unit including the support roller and the belt is detachably attached to a device body, a second unit including the tension member and the pressing mechanism is attached to the first unit so as to be movable between an operating position that applies tension to the belt and a release position that releases the tension, and a positioning section is provided in the device body that positions the second unit at the operating position by the relative movement of the first unit when attached or detached from the device body, and releases the second unit from being positioned at the operating position. [Effects of the Invention]

[0005] According to the present invention, the tension of the belt can be released by removing the belt together with the support rollers, and the tension of the belt can be applied by installing the belt together with the support rollers. [Brief explanation of the drawings]

[0006] [Figure 1] 1 is a schematic diagram illustrating the configuration of an electrophotographic color printer (hereinafter referred to as "printer") as an image forming apparatus according to an embodiment. [Figure 2] FIG. 2 is an explanatory diagram of a first unit including a fixing belt and a support roller for the belt. [Figure 3] FIG. 4 is an explanatory diagram of a state in which the first unit is removed from the fixing device main body. [Figure 4] FIG. 4 is an explanatory diagram of a state in which the first unit is attached to the fixing device main body. [Figure 5] 10 is an explanatory diagram of the change in the spring during the process of attaching the first unit from the removed state. [Figure 6] FIG. [Figure 7] FIG. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a schematic diagram of an electrophotographic color printer (hereinafter referred to as "printer") as an image forming apparatus according to the embodiment. This printer 100 includes four image forming units 1Y, 1M, 1C, and 1K for forming toner images of yellow (Y), magenta (M), cyan (C), and black (K), a transfer unit 30 as an intermediate transfer device, a secondary transfer device 40 including a secondary transfer unit 41, a heater 490, and a pressure device 480, a cassette 60 that stores a recording material P as an object to be conveyed, and a fixing device 90.

[0008] The four image forming units 1Y, 1M, 1C, and 1K, which make up the image forming section, use different color toners (Y, M, C, and K) as powder developers. Other than that, they have the same configuration. The image forming units 1Y, 1M, 1C, and 1K each include drum-shaped photoreceptors 2Y, 2M, 2C, and 2K that serve as image carriers, drum cleaning devices 3Y, 3M, 3C, and 3K, static eliminators, charging devices 6Y, 6M, 6C, and 6K, and developing devices 8Y, 8M, 8C, and 8K.

[0009] The surfaces of photoreceptors 2Y, 2M, 2C, and 2K, which have been uniformly charged by charging devices 6Y, 6M, 6C, and 6K, are optically scanned with exposure light such as laser light emitted from optical writing unit 101 disposed above image forming units 1Y, 1M, 1C, and 1K, forming electrostatic latent images for each color. These electrostatic latent images are developed by developing devices 8Y, 8M, 8C, and 8K containing toner of each color into toner images T for each color. The toner images are formed on photoreceptor 2. The toner images T on photoreceptors 2Y, 2M, 2C, and 2K are primarily transferred onto and carried on front surface 31a of intermediate transfer belt 31, which is an endless belt member.

[0010] Below the image forming units 1Y, 1M, 1C, and 1K, there is disposed a transfer unit 30, which is a belt unit that moves (rotates) endlessly in a clockwise direction in the drawing while tensioning an intermediate transfer belt 31, and which is a primary transfer device. In this embodiment, the surface movement direction of the intermediate transfer belt 31 is defined as a belt movement direction a.

[0011] In addition to the intermediate transfer belt 31, the transfer unit 30 includes a drive roller 32, a secondary transfer back roller 33, a cleaning backup roller 34, four primary transfer rollers 35Y, 35M, 35C, and 35K, and a pre-transfer roller 37. The intermediate transfer belt 31 is wound around, supported, and stretched by the drive roller 32, the secondary transfer back roller 33, the cleaning backup roller 34, the primary transfer rollers 35Y, 35M, 35C, and 35K, and the pre-transfer roller 37. The intermediate transfer belt 31 is endlessly moved and conveyed in the clockwise direction in the drawing by the rotational force of the drive roller 32, which is driven to rotate in the clockwise direction in the drawing by a driving means such as a drive motor.

[0012] A belt-type secondary transfer device 40 is disposed below the outer side of the loop of the intermediate transfer belt 31. The secondary transfer unit 41 includes a secondary transfer belt 406, which is a belt member and a transfer member. The secondary transfer belt 406 is wound around a separation roller 401, a driven roller 402, a first blade opposing roller and a tension roller 403 constituting a tension applying member, a second blade opposing roller 404, and a secondary transfer roller 405. The secondary transfer unit 41 also includes a plurality of cleaning members 407 and 408.

[0013] A cassette 60 is disposed below the secondary transfer device 40 and serves as a storage section capable of storing a stack of multiple recording materials P. This cassette 60 has a roller 60a in contact with the topmost recording material P of the stack, and by rotating the roller 60a at a predetermined timing, the recording material P is sent from the cassette 60 toward a conveying path 65 leading to the secondary transfer nip N2. The recording material P sent to the conveying path 65 is sent to the secondary transfer nip N2 by a registration roller pair 61 at a timing synchronized with the toner image on the front surface 31a of the intermediate transfer belt 31 within the secondary transfer nip N2.

[0014] The toner image on the front surface 31a of the intermediate transfer belt 31 is transferred onto the recording material P at the secondary transfer nip N2 by the action of the secondary transfer electric field and nip pressure, and becomes a full-color toner image in combination with the white color of the recording material P.

[0015] A fixing device 90 is disposed downstream of the secondary transfer nip N2 in the recording material conveyance direction b. This fixing device 90 is a belt device equipped with a fixing belt 94. As shown in FIG. 2, the fixing device 90 includes a heating roller 91, a fixing roller 93, a support roller 96, and a tension roller 95, which also functions as a tension member, as support rollers for the fixing belt 94. The fixing device 90 also includes a pressure roller 92 that contacts the fixing roller 93 across the fixing belt 94. The recording material P with the transferred toner image is fed into the fixing device 90 and sandwiched in the fixing nip where the fixing roller 93 and the pressure roller 92 come into contact. The fixing device 90 applies pressure to the nip and transfers heat from the heating roller 91, which has an internal heat source, to the recording material P via the fixing belt 94, softening and fusing the toner in the full-color toner image. After fusing, the recording material P is ejected from the fixing device 90 and discharged outside the apparatus.

[0016] FIG. 2 is an explanatory diagram of a first unit 910 including a fixing belt 94 and belt support rollers. FIG. 2(a) is a perspective view. The first unit 910 includes a front frame 911 and a rear frame 912, which rotatably support the heating roller 91, fixing roller 93, and support roller 96 in their fixed positions. The front frame 911 includes a receiving portion 913 for the heating roller 91 and a receiving portion 914 for the fixing roller 93 on its front surface. These are attached to the fixing device frame, which will be described later. The front frame 911 also includes a through-hole 915 through which the tip of a positioning rod 921, which is integrated with the pressing mechanism of the tension roller 95, protrudes.

[0017] 2(b) is a perspective view of a pressing mechanism 920 for the tension roller 95 on the front side, which is provided on the back surface of the front frame 911. The pressing mechanism 920 includes a tension bracket 923 that is guided so as to be able to move back and forth in the tension direction by a guide member 922 fixed to the back surface of the front frame 911. This tension bracket 923 includes a slide window 924 that houses a slider member 95b that holds the shaft 95a of the tension roller 95 so as to be able to slide in the tension direction.

[0018] The tension bracket 923 is equipped with a tension spring 925 that pushes the slider member 95b in the direction that applies tension, and has a positioning rod 921 fixed thereto. The guide member 922 and tension bracket 923 are connected by a tension spring 926 that serves as a release biasing means. This tension spring 926 constantly biases the tension bracket 923 to retract in the direction opposite to the tension direction. Components similar to those of the pressing mechanism 920 attached to the front frame 911 described above are also attached to the rear frame 912. On both the front and rear sides, the shaft 95a of the tension roller 95 and the tension spring 925 that constitutes the pressing mechanism are held by the tension bracket 923, and these together constitute a second unit.

[0019] FIG. 3 is an explanatory diagram of the first unit 910 removed from the fixing device main body. FIG. 3(a) also shows the front frame 930 of the fixing device main body. The front frame 930 has a frame-side receiving portion 931 that receives the receiving portion 913 of the heating roller 91, a frame-side receiving portion 932 that receives the receiving portion 914 of the fixing roller 93, and a positioning portion 933 against which the positioning rod 921 abuts. The same is true on the rear side of the device. FIG. 3(b) is an enlarged view showing the state of the pressing mechanism 920. The tension spring 926 pulls the tension bracket 923, and the tension spring 925 remains at its natural length while the tension roller 95 is retracted in the direction opposite to the tension application direction to assume a retracted position.

[0020] 4 is an explanatory diagram of the state in which the first unit 910 is attached to the fixing device main body. As shown in FIG. 4(a), the frame side receiving portion 931 receives the receiving portion 913 of the heating roller 91, the frame side receiving portion 932 receives the receiving portion 914 of the fixing roller 93, and the positioning portion 933 receives the positioning rod 921. As shown in FIG. 4(b), the tension spring 926 is extended and the tension spring 925 is compressed, urging the tension roller 95 in the tensioning direction, and the tension roller 95 is in the operating position.

[0021] 5 is an explanatory diagram of changes in the spring during the process of installing the first unit 910 from the removed state. As shown in FIG. 5(a), both the tension spring 926 and the tension bracket 923 are at their natural lengths when the first unit 910 is not set in the fixing device main body. When the first unit 910 is moved toward the fixing device to be installed as indicated by arrow A in FIG. 5(a), the positioning rod 921 is pressed against a positioning portion 933 of a front frame 930 of the fixing device main body as shown in FIG. 5(b), thereby fixing the first unit 910 in the set position, and only the force of the tension spring 925 acts on the tension roller 95.

[0022] As described above, according to the fixing device of this embodiment, a first unit is configured with a plurality of rollers, including at least one tension roller, and a fixing belt that is stretched between the rollers and can be driven in a circulating manner. The tension roller and a pressing mechanism for pressing the tension roller against the fixing belt are configured as a second unit. When the first unit is removed from the fixing device, the second unit is released from its positioning and the tension on the fixing belt is released. The second unit is configured to be pulled from the first unit by a spring, so that the second unit can be smoothly retracted and the tension on the fixing belt is released when the fixing unit is removed. In this way, the belt tensioning means is simplified, and when the belt unit is removed from the main body, the positioning is automatically released and the belt tensioning means is retracted inside the belt unit by the spring. This allows belt replacement without removing the belt tensioning means.

[0023] As shown in FIG. 3, at least one of the side plates of the first unit 910 is smaller than the inner circumference of the fixing belt 94 when tension is released, so the belt can be pulled out without removing any components after tension is released. The belt does not need to be completely tensioned; it can be removed if the tension is weaker than when the belt is in operation. In particular, if there are no guides, such as guide rubbers, on either end of the belt, the balance between the friction of the rollers and the pulling force is achieved, so the belt can be removed by weakening the tension without completely releasing the tension. This type of tension weakening configuration can be achieved by changing the amount the tension roller 95 retracts.

[0024] In the above embodiment, the pressing mechanism 920 is provided on the tension bracket 923 that constitutes the second unit. However, instead, the pressing mechanism 920 may be provided on, for example, the front frame 930 of the fixing device main body. Fig. 6(a) is an explanatory diagram that schematically shows such a modified example, and Fig. 6(b) is an explanatory diagram that schematically shows the corresponding part of the above embodiment. As shown in Fig. 6(a), a spring housing 800 is fixed to the front frame 930, and a slider member 801 and a tension spring 802 that pushes out the slider member 801 are housed in this housing, constituting the pressing mechanism 920.

[0025] On the first unit 910 side, shaft 95a of tension roller 95 is rotatably held by bracket 803, which is guided by guide member 222 so as to be able to advance and retreat in the tension direction, and pressing rod 804, which contacts slider member 801 of pressing mechanism 920, is fixedly provided. According to this modification, pressing mechanism 920 is provided on the fixing device main body side, so that it is superior in strength, and there is no need to include a pressing mechanism in the second unit, which is a movable part, and the structure of the movable part can be simplified.

[0026] FIG. 7(a) is an explanatory diagram showing a schematic diagram of another modified example. FIG. 7(a) is an explanatory diagram showing a state in which a first unit 910 of this modified example has been removed from the fixing device main body. For comparison, FIGS. 7(c) and 7(d) are explanatory diagrams showing schematic diagrams of corresponding parts of the above embodiment. In this modified example, similar to the modified example of FIG. 6(a), a pressing mechanism 920 consisting of a spring accommodating case 800, a slider member 801, and a tension spring 802 is provided in the fixing device main body, and the configuration of the second unit, which is a movable part, is further simplified.

[0027] Specifically, a configuration is adopted in which shaft 95a of tension roller 95 moves within a guide groove of rail member 820 provided on first unit 910. Shaft 95a of tension roller 95 is pressed by slider member 801 of pressing mechanism 920 provided on the fixing device main body side to apply tension to fixing belt 94. It is preferable to add a spring that pulls shaft 95a of tension roller 95 to the right in the figure so that tension roller 95 retracts from the fixing belt 94 side when first unit 910 is removed from the fixing device main body as shown in FIG. 7(b).

[0028] As shown in FIG. 7B, when the first unit 910 is removed from the fixing device main body, a gap G1 is created between the back surface of the fixing belt 94 and the tip of the rail member 820. If only the tension roller 95 is moved, as in this modified example, the tip of the rail member 820 must be positioned as close as possible to the path of the fixing belt 94 during the fixing operation. Therefore, even when the tension roller 95 is retracted, the tip of the rail member 820 remains, making it impossible to ensure a sufficient gap G1. A larger gap G1 could be achieved by providing an expandable mechanism to the rail member 820, but this would complicate the mechanism. In contrast, as shown in FIG. 7D, the above-described embodiment ensures a relatively large gap G2 between the tension roller 95 and the back surface of the fixing belt 94. Therefore, this embodiment is advantageous in terms of ensuring "space between the belt and the pressing mechanism" for removing the fixing belt 94.

[0029] Although the preferred embodiment of the present invention has been described above, the present invention is not limited to such a specific embodiment, and unless otherwise specifically limited in the above description, various modifications and changes are possible within the spirit and scope of the present invention as set forth in the claims. For example, the image forming apparatus may be a single copier or facsimile machine, or a multifunction machine that combines at least two of the functions of a copier, printer, facsimile, and scanner, instead of a printer. The belt device is not limited to a fixing belt device and may be applied to various belt devices. The effects described in the embodiments of the present invention are merely a list of the most favorable effects resulting from the present invention, and the effects of the present invention are not limited to those described in the embodiments of the present invention. [Explanation of symbols]

[0030] 1C: Image forming unit 1K: Image forming unit 1M: Image forming unit 1Y: Image forming unit 2: Photoreceptor 2C: Photoreceptor 2K: Photoreceptor 2M: Photoreceptor 2Y: Photoreceptor 3C: Drum cleaning device 3K: Drum cleaning device 3M: Drum cleaning device 3Y: Drum cleaning device 6C: Charging device 6K: Charging device 6M: Charging device 6Y: Charging device 8C:Developing device 8K: Developing device 8M: Developing device 8Y: Developing device 30: Transcription unit 31: Intermediate transfer belt 31a: Front 32: Drive roller 33: Secondary transfer back roller 34: Cleaning backup roller 35C: Primary transfer roller 35K: Primary transfer roller 35M: Primary transfer roller 35Y: Primary transfer roller 37: Pre-transfer roller 40: Secondary transfer device 41: Secondary transfer unit 60: Cassette 60a: Laura 61: Registration roller pair 65: Transport path 90: Fixing device 91: Heating roller 92: Pressure roller 93: Fuser roller 94: Fixing belt 95: Tension roller 95a: Axis 95b: slider member 96: Support roller 100: Printer 101: Optical writing unit 401: Separation roller 402: Driven roller 403: Tension roller 404: Second blade opposing roller 405: Secondary transfer roller 406: Secondary transfer belt 407: Cleaning material 408: Cleaning material 480: Pressure device 490: Heater 910: First Unit 911: Front frame 912: Rear frame 913: Receiving 914: Receiving 915: Through hole 920: Pressing mechanism 921: Positioning rod 922: Guide member 923: Tension bracket 924: Sliding window 925: Tension spring 926: Extension spring 930: Previous frame 931: Frame side support 932: Frame side support 933: Positioning section 925: Tension spring A: Arrow N2: Secondary transfer nip P: Recording material T: Toner image [Prior art documents] [Patent documents]

[0031] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-18238

Claims

1. A belt device including a belt, a support member that supports the belt, and a tension member that contacts the belt, a first unit including the support member and the belt is provided detachably with respect to the device body; a second unit including at least the tension member is provided on the first unit so as to be movable between an operating position where tension is applied to the belt and a release position where the tension is released; A belt device characterized in that the second unit can be switched between the operating position and the release position by attaching or detaching the first unit to or from the device body.

2. 2. The belt device according to claim 1, The belt device further comprises a pressing mechanism for pressing the tension member against the belt.

3. The belt device of claim 2, The belt device is characterized in that the pressing mechanism is included in the second unit.

4. 4. The belt device according to claim 1, A belt device characterized in that a positioning portion is provided on the device body, which positions the second unit at the operating position and releases the second unit from the operating position by attaching or detaching the first unit to or from the device body.

5. 5. The belt device according to claim 4, a release biasing means for biasing the second unit toward the release position, and the positioning portion for positioning the second unit at the operating position against the biasing force of the release biasing means.

6. 6. The belt device according to claim 1, A belt device, characterized in that at least one of the side plates of the first unit is smaller than the inner circumference of the belt in a released state.

7. 7. The belt device according to claim 1, which is a fixing device, further comprising a heating and pressurizing means.

8. In an image forming apparatus equipped with a fixing device, 8. An image forming apparatus using the fixing device according to claim 7 as a fixing device.

Images