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 Art

[0002] Conventionally, a belt device including a belt, a plurality of 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 is known. For example, Patent Document 1 describes a belt conveying device having a belt tension applying means including a driving roller, an endless belt suspended from a tension roller, a support member that rotatably supports the tension roller, and a biasing member that biases the support member in a direction to apply tension to the endless belt. When attaching the belt tension applying means, the belt tension applying means can swing about the rotation axis of the tension roller against the biasing force of the biasing member, and at a predetermined position, has an engaging portion that engages and holds an engaged portion of the belt tension applying means. According to this, it is said that the assembly and removal operations of the belt tension applying means can be easily performed without using a dedicated tool.

Summary of the Invention

Problems to be Solved by the Invention

[0003] However, when removing, when removing the belt together with the support rollers, removing the belt from the support rollers and releasing the tension when replacing the belt, it is necessary to perform the operation of removing the belt together with the support rollers and the operation of removing the belt tension applying means respectively, which takes a lot of man-hours. Also, when attaching, it is necessary to perform the operation of attaching the belt tension applying means and the operation of attaching the belt together with the support rollers respectively, which takes a lot of man-hours.

Means for Solving the Problems

[0004] In order to solve the above-described problems, the present invention provides a belt device including a belt, a support member that supports the belt, and a tension member that abuts against the belt. A first unit including the support member and the belt is detachably provided with respect to a device main body. A second unit including at least the tension member is provided movably on the first unit between an operating position that is a position on a frame of the first unit and applies tension to the belt and a release position that is a position on the frame where the tension is released. A pressing mechanism that presses the tension member against the belt is provided on the first unit. By attaching the first unit to the device main body, the second unit is brought into contact with and positioned at the operating position, and a positioning portion is provided on the device main body such that the contact with the second unit is released and the positioning at the operating position is released by removing the first unit from the device main body. By attaching and detaching the first unit to and from the device main body, the second unit can be switched between the operating position and the release position The pressing mechanism includes a spring. When the second unit is in the operating position, the spring biases the tension member in the tension-applying direction. When the second unit is in the release position, the spring does not bias the tension member in the tension-applying direction. It is characterized by the above.

Effect of the Invention

[0005] According to the present invention, the tension of the belt can be released by the operation of removing the belt together with the support roller, and the tension of the belt can be applied by the operation of attaching the belt together with the support roller.

Brief Description of the Drawings

[0006]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Mode for Carrying Out the Invention

[0007] Hereinafter, embodiments according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration 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, 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 for storing a recording material P as an object to be conveyed, a fixing device 90, and the like.

[0008] The four image forming units 1Y, 1M, 1C, 1K that form the image forming unit use toners of Y, M, C, and K in different colors as powder developers. Other than that, they have the same configuration. The image forming units 1Y, 1M, 1C, 1K include drum-shaped photoreceptors 2Y, 2M, 2C, 2K as image carriers, drum cleaning devices 3Y, 3M, 3C, 3K, a charge removing device, charging devices 6Y, 6M, 6C, 6K, developing devices 8Y, 8M, 8C, 8K, and the like.

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

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

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

[0012] Below the outside of the loop of the intermediate transfer belt 31, there is disposed a belt-type secondary transfer device 40 including a secondary transfer unit 41 having a secondary transfer belt 406 that 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 tension roller 403 that constitutes a first blade opposing roller and 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, 408.

[0013] Below the secondary transfer device 40, a cassette 60 serving as a storage unit capable of storing a plurality of stacked recording materials P is disposed. This cassette 60 has a roller 60a in contact with the topmost recording material P in the stack, and by rotationally driving this roller 60a at a predetermined timing, the recording material P is sent out from the cassette 60 toward a conveyance path 65 leading to the secondary transfer nip N2. The recording material P sent out onto the conveyance path 65 is sent out to the secondary transfer nip N2 by the 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 batchwise secondary 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 together with the white color of the recording material P, it becomes a full-color toner image.

[0015] Downstream of the secondary transfer nip N2 in the recording material conveyance direction b, a fixing device 90 is disposed. This fixing device 90 is a belt device including a fixing belt 94 as a belt. 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 is also 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 with the fixing belt 94 interposed therebetween. The recording material P onto which the toner image has been transferred is fed into the fixing device 90 and is sandwiched between the fixing nip where the fixing roller 93 and the pressure roller 92 are in contact. The fixing device 90 has pressure applied to the nip portion and transfers heat from the heating roller 91, which has a heat source inside, to the recording material P through the fixing belt 94, softening the toner in the full-color toner image and fixing it. The recording material P after fixing is discharged from within the fixing device 90 and discharged outside the machine.

[0016] FIG. 2 is an explanatory view of a first unit 910 including a fixing belt 94 and belt support rollers. FIG. 2(a) is a perspective view thereof. This first unit 910 includes a front frame 911 and a rear frame 912, and rotatably supports a heating roller 91, a fixing roller 93, and a support roller 96 at fixed positions therebetween. The front frame 911 includes, on its front surface, a receiving portion 913 for the heating roller 91 and a receiving portion 914 for the fixing roller 93. These serve as attachment portions to a fixing device frame described later. The front frame 911 also includes a through hole 915, and the tip of a positioning rod 921 integrated with the pressing mechanism of the tension roller 95 protrudes through the through hole 915.

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

[0018] The tension bracket 923 includes a tension spring 925 that pushes out the slider member 95b in the direction of applying tension, and the positioning rod 921 is fixedly provided thereon. The guide member 922 and the tension bracket 923 are connected by a tension spring 926 as a means for releasing biasing force. This tension spring 926 biases the tension bracket 923 to always pull it in the direction opposite to the tension direction. Components similar to those of the pressing mechanism 920 attached to the front frame 911 are also attached to the rear frame 912. On each of the front side and the rear side, 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 constitute a second unit.

[0019] FIG. 3 is an explanatory view of the state where the first unit 910 is removed from the fixing device main body. FIG. 3(a) shows the front frame 930 of the fixing device main body combined. The front frame 930 includes 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 applies to the back 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 is in the retracted position where the tension roller 95 is pulled in the direction opposite to the tension application direction with the natural length.

[0020] FIG. 4 is an explanatory view of the state where the first unit 910 is mounted on 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, the tension spring 925 is compressed to bias the tension roller 95 in the tension application direction, and the tension roller 95 is in the operating position.

[0021] FIG. 5 is an explanatory view of the spring change during the process of mounting 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 in the natural length when the first unit 910 is not set on the fixing device main body. As shown by the arrow A in FIG. 5(a), when the first unit 910 is moved toward the fixing device and attached, as shown in FIG. 5(b), the positioning rod 921 is pressed against the positioning portion 933 of the front frame 930 of the fixing device main body and fixed at 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 the present embodiment, a plurality of rollers including at least one tension roller and a fixing belt that can be stretched between the rollers and driven in a circulating manner are configured as a first unit, and the tension roller and a pressing mechanism for pressing it against the fixing belt are configured as a second unit. When the first unit is removed from the fixing machine, the positioning of the second unit is released and the tension of the fixing belt is released. Then, by configuring the second unit to be pulled by a spring from the first unit, the second unit can be smoothly retracted when the fixing unit is removed, and the tension of the fixing belt is released. In this way, the belt tension applying means is simplified, and when the belt unit is removed from the main body, the positioning is automatically released, and the belt tension applying means is retracted inside the belt unit by the spring. Therefore, the belt can be replaced without the need to remove the belt tension applying means.

[0023] As shown in FIG. 3, at least one of the both side plates of the first unit 910 is smaller than the inner circumference of the fixing belt 94 in a state where the tension is released. Therefore, the belt can be pulled out without the need to remove the parts after the tension is released. To remove the belt, it is not necessary to reduce the tension to zero, and the belt can be removed if the tension is weaker than the operating state. In particular, when there is no retaining guide such as retaining guide rubber near both ends of the belt, it is a balance between the friction of the roller and the pulling force. Therefore, even if the tension is not completely released, the belt can be removed by weakening the tension. Such a configuration for weakening the tension can be realized by changing the amount of retraction of the tension roller 95.

[0024] In the above-described embodiment, the pressing mechanism 920 is provided in the tension bracket 923 that constitutes the second unit. Alternatively, the pressing mechanism 920 may be provided in, for example, the front frame 930 of the fixing device main body. FIG. 6(a) is an explanatory diagram schematically showing such a modification, and FIG. 6(b) is an explanatory diagram schematically showing the corresponding part of the above-described embodiment. As shown in FIG. 6(a), a spring housing case 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 case, constituting the pressing mechanism 920.

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

[0026] FIG. 7(a) is an explanatory diagram schematically showing another modification. FIG. 7(a) is an explanatory diagram of a state in which the first unit 910 of this modification is taken out from the fixing device main body. FIGS. 7(c) and 7(d) are explanatory diagrams schematically showing the corresponding parts of the above-described embodiment for comparison. In this modification, similar to the modification of FIG. 6(a), in addition to providing the pressing mechanism 920 composed of the spring housing case 800, the slider member 801, and the tension spring 802 on the fixing device main body, the configuration of the second unit, which is a movable part, is further simplified.

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

[0028] As shown in FIG. 7(b), when the first unit 910 is taken out of the fixing device main body, a gap G1 is generated between the back surface of the fixing belt 94 and the tip of the rail member 820. As in this modification, if only the tension roller 95 is to be moved, it is necessary to position the tip of the rail member 820 extremely close to the vicinity of the orbit during the fixing operation of the fixing belt 94. For this reason, even if the tension roller 95 is retracted, the tip of the rail member 820 remains, and a sufficient gap G1 cannot be ensured. To ensure a wider gap G1, a mechanism for expanding and contracting may be provided in the rail member 820, but the mechanism becomes complicated. In this regard, in the above-described embodiment as shown in FIG. 7(d), a relatively wide gap G2 can be ensured between the tension roller 95 side and the back surface of the fixing belt 94. Therefore, it is advantageous from the viewpoint of securing the "space between the belt and the pressing mechanism" for removing the fixing belt 94.

[0029] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to such specific embodiments, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims, unless otherwise particularly limited in the above description. For example, the image forming apparatus may be a copying machine, a facsimile machine alone, or a multifunction machine having at least two functions among a copying machine, a printer, a facsimile machine, and a scanner, instead of a printer. The belt device is not limited to the fixing belt device and can be applied to various belt devices. The effects described in the embodiments of the present invention are merely a list of the most preferred 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 Signs

[0030] 1C: Image forming unit 1K: Image forming unit 1M: Image forming unit 1Y: Image forming unit 2: Photoconductor 2C: Photoconductor 2K: Photoconductor 2M: Photoconductor 2Y: Photoconductor 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: Transfer unit 31: Intermediate transfer belt 31a: Front side 32: Driving 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: Roller 61: Registration roller pair 65: Conveyor path 90: Fixing device 91: Heating roller 92: Pressing roller 93: Fixing roller 94: Fixing belt 95: Tension roller 95a: Shaft 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 member 408: Cleaning member 480: Pressing device 490: Heater 910: First unit 911: Front side frame 912: Rear side frame 913: Receiving part 914: Receiving part 915: Through hole 920: Pressing mechanism 921: Positioning rod 922: Guide member 923: Tension bracket 924: Slide window 925: Tension spring 926: Pulling spring 930: Front frame 931: Frame side receiving part 932: Frame side receiving part 933: Positioning part 925: Tension spring A: Arrow N2: Secondary transfer nip P: Recording material T: Toner image

Prior art documents

Patent documents

[0031]

Patent Document 1

Claims

1. In a belt device comprising a belt, a support member for supporting the belt, and a tension member that abuts against the belt, a first unit including the support member and the belt is detachably provided with respect to the apparatus main 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 at a position in the frame of the first unit where tension is applied to the belt and a release position at a position in the frame where the tension is released, and a pressing mechanism for pressing the tension member against the belt is provided on the first unit, a positioning portion is provided on the apparatus main body such that, by attaching the first unit to the apparatus main body, it abuts against the second unit and positions the second unit at the operating position, and also, by removing the first unit from the apparatus main body, the abutment with the second unit is released and the positioning at the operating position is released, by attaching and detaching the first unit to and from the apparatus main body, it is possible to switch the second unit between the operating position and the release position, the pressing mechanism includes a spring, and the spring biases the tension member in the tension-applying direction when the second unit is in the operating position, and does not bias the tension member in the tension-applying direction when the second unit is in the release position. A belt device characterized by this.

2. In the belt device according to Claim 1, the first unit is provided with a release biasing means for biasing the second unit toward the release position, and the positioning portion positions the second unit at the operating position against the biasing force of the release biasing means. A belt device characterized by this.

3. In a belt device comprising a belt, a support member for supporting the belt, and a tension member that abuts against the belt, a first unit including the support member and the belt is detachably provided with respect to the apparatus main 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 at a position in the frame of the first unit where tension is applied to the belt and a release position at a position in the frame where the tension is released, and a pressing mechanism for pressing the tension member against the belt is provided on the first unit, By attaching the second unit to the main body of the first unit, the second unit abuts against the second unit to position the second unit at the operating position, and by removing the second unit from the main body of the first unit, the abutment with the second unit is released and the positioning at the operating position is released. A positioning portion is provided on the main body of the device. By attaching and detaching the second unit to and from the main body of the first unit, it is possible to switch the second unit to the operating position and the release position. The first unit is provided with a release biasing means for biasing the second unit toward the release position. The positioning portion positions the second unit at the operating position against the biasing force of the release biasing means. A belt device characterized by this.

4. In the belt device according to any one of Claims 1 to 3, The pressing mechanism is included in the second unit and provided in the first unit. A belt device characterized by this.

5. In the belt device according to any one of Claims 1 to 4, The support member includes a first roller and a second roller supported by the frame. The positioning portion is provided between a receiving portion for the first roller and a receiving portion for the second roller in the main body of the device. A belt device characterized by this.

6. In the belt device according to any one of Claims 1 to 5, At least one of both side plates of the first unit is smaller than the inner circumference of the belt in a state where the tension is released. A belt device characterized by this.

7. The belt device according to any one of Claims 1 to 6 is a fixing device, and further includes heating and pressing means. A fixing device characterized by this.

8. In an image forming apparatus provided with a fixing device, An image forming apparatus characterized by using the fixing device according to Claim 7 as the fixing device.

Images