Endless belt and image forming apparatus

Abstract

To provide an endless belt that can prevent damage to a belt member that is provided with projection members with ends for regulating belt skew.SOLUTION: An endless belt to which a toner image formed on an image carrier is transferred, has: an endless belt member 1a; reinforcement members 3 that are provided at the ends in the width direction of the belt member along an outer peripheral surface of the belt member; and projection members 2 with ends that are provided at the ends in the width direction of the belt member along an inner peripheral surface of the belt member. An opening is formed between both ends of the projection member with ends, and the reinforcement member is formed with an overlapping part where a one end area and the other end area of the reinforcement member overlap in the circumferential direction of the belt member. When the length of the opening in the circumferential direction is defined as L1, and the length of the overlapping part as L2, the relationship of L2>L1 is established. The position of the opening in the circumferential direction is located in the area of the overlapping part.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an endless belt for use in copying machines, printers, etc., using an electrophotographic system or an electrostatic recording system, and to an image forming apparatus using the same. [Background technology]

[0002] Conventionally, image forming apparatuses have been widely used in which a toner image formed on an image carrier is transferred to an intermediate transfer belt passing through a primary transfer section, conveyed to a secondary transfer section, and then secondary-transferred all at once to a sheet fed to the secondary transfer section. This intermediate transfer belt is usually formed in an endless shape, and is supported under tension by being stretched over one or more tension rollers (drive roller, tension roller, support roller, etc.).

[0003] When the intermediate transfer belt is transported (driven in a circulating manner) while being tensioned by a number of tension rollers, a phenomenon called "belt shift" may occur in which the intermediate transfer belt moves in the width direction (a direction substantially perpendicular to the transport direction). When the belt shift occurs, there is a risk of problems such as the end of the intermediate transfer belt in the width direction coming into contact with other members. For this reason, a rib regulating method is known in which a rib, which is a protruding member, is provided on the inner peripheral surface of the end of the intermediate transfer belt in the width direction, and a regulating member capable of coming into contact with the rib is provided on the end of the tension roller in the rotation axis direction to regulate the belt shift.

[0004] When the rib is provided on the intermediate transfer belt, the rib having ends is adhered from one end to the inner peripheral surface of the intermediate transfer belt. However, due to variations in the components of the intermediate transfer belt and the rib and variations in adhesion, it is difficult to provide the rib continuously along the entire length of the intermediate transfer belt. This results in the formation of an opening where the rib is not continuously provided along the length of the rib.

[0005] In the case where the rib end has an opening as described above, when the belt area corresponding to the opening is wound around the outer surface of the tension roller while the intermediate transfer belt is rotating, a large load acts on the intermediate transfer belt due to bending. As a result, the belt may be damaged due to the load acting on it every time it is wound around the tension roller.

[0006] Therefore, an image forming device has been proposed in which the end of the end rib is made thinner and tapered than the other parts, thereby increasing the flexibility of the intermediate transfer belt corresponding to the opening of the rib, and reducing the load acting on the belt, thereby suppressing damage to the intermediate transfer belt (Patent Document 1). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent Publication No. 2002-278361 Summary of the Invention [Problem to be solved by the invention]

[0008] However, as described above, in the configuration in which the shape of the rib end is made thin, the opening of the rib becomes partially longer, and the area where the rib abuts against the belt shift regulating member becomes smaller, which causes the belt to shift more when the opening of the rib passes through the belt shift regulating member, bending the belt and locally increasing the stress on the belt.

[0009] In addition, when the rib end shape is not narrowed, the belt shift is smaller than when the rib end shape is narrowed, but the stress on the belt is locally high when the rib opening passes through the belt shift regulating portion. If the belt is repeatedly subjected to locally high stress during belt conveyance, the belt may be fatigued.

[0010] The present invention has been made in view of the problems existing in such conventional technologies, and an object thereof is to provide an endless belt capable of suppressing damage to a belt member provided with an end-shaped protruding member for regulating the approach of a belt, and an image forming apparatus using the same.

Means for Solving the Problems

[0011] A typical configuration according to the present invention for achieving the above object is an endless belt for transferring a toner image formed on an image carrier, which includes an endless belt member, a reinforcing member provided along the outer peripheral surface at a widthwise end of the belt member, and an end-shaped protruding member provided along the inner peripheral surface at a widthwise end of the belt member. An opening is formed between both end-shaped ends of the protruding member, and an overlapping portion where the reinforcing member overlaps in the circumferential direction of the belt member is formed in the reinforcing member. When the distance of the opening in the circumferential direction is L1 and the distance of the overlapping portion is L2, they have a relationship of L1 < L2, and the position of the opening in the circumferential direction is located within the region of the overlapping portion.

Effects of the Invention

[0012] According to the present invention, by arranging the opening of the rib between the overlapping portions of the reinforcing tapes, the stress applied to the belt can be reduced.

Brief Description of the Drawings

[0013] [Figure 1] Cross-sectional view of the image forming apparatus [Diagram 2] Enlarged perspective view of the end of the tension roller [Diagram 3] Schematic view showing a cross-section of the intermediate transfer belt [Figure 4] Cross-sectional view showing belt approach regulation [Diagram 5] Perspective view of the intermediate transfer belt [Figure 6] Graph showing the stress applied to the belt by the layers of the reinforcing tape [Figure 7] Perspective view of the intermediate belt of the second embodiment DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Next, an endless belt according to a preferred embodiment of the present invention and an image forming apparatus using the same will be described with reference to the drawings.

[0015] [First embodiment] <Image forming device> Fig. 1 is an explanatory diagram of the configuration of an image forming apparatus in this embodiment. As shown in Fig. 1, an image forming apparatus 100 has image forming units 101Y, 101M, 101C, and 101K for yellow Y, magenta M, cyan C, and black K arranged along an intermediate transfer belt 1. In other words, the image forming apparatus of this embodiment is a full-color printer of a so-called tandem type intermediate transfer system.

[0016] The image forming units 101Y, 101M, 101C, and 101K have different toner colors but are substantially the same in configuration. For example, in the case of the yellow image forming unit 101Y, the peripheral surface of the rotating photosensitive drum 102 is charged by a charging roller 103, and an electrostatic latent image is formed by exposing the peripheral surface to an image by an exposure device 104. This electrostatic latent image is developed with toner by a developing device 105 to form a yellow toner image, and the toner image is primarily transferred to the rotating intermediate transfer belt 1 by applying a bias to a primary transfer roller 106.

[0017] Similarly, a magenta toner image is transferred onto the intermediate transfer belt 1 in the image forming station 101M, a cyan toner image is transferred onto the intermediate transfer belt 1 in the image forming station 101C, and a black toner image is transferred onto the intermediate transfer belt 1 in the image forming station 101K, so that a color image is formed.

[0018] In synchronization with the formation of the toner image, the sheet S is transported from a sheet cassette 107 to a secondary transfer section by a transport roller 108. Then, the toner image transferred onto the intermediate transfer belt 1 is secondarily transferred onto the sheet S by application of a bias to a secondary transfer roller 109 in the secondary transfer section, and the sheet S is heated and pressurized as it passes through a fixing section 110, so that the sheet S is discharged to a discharge section 111 in a state in which the toner image is fixed.

[0019] <Intermediate transfer unit> As shown in FIG. 1, the intermediate transfer belt 1 is stretched across a drive roller 201, a tension roller 202, support rollers 203 and 204, and a primary transfer roller 106, which together constitute an intermediate transfer unit 200 that is detachable from the main body of the image forming apparatus.

[0020] The driving roller 201 forms a secondary transfer portion by sandwiching the intermediate transfer belt 1 between itself and the secondary transfer roller 109. The driving roller 201 also functions as a secondary transfer inner roller that faces the secondary transfer roller 109 with the intermediate transfer belt 1 interposed therebetween.

[0021] The support roller 204 has a crown shape in which the outer diameter is maximum at the approximate center in the axial direction and gradually decreases toward both ends. This is to prevent the support roller 114 from bending at the center due to the tension of the intermediate transfer belt 1, causing wrinkles in the central portion of the intermediate transfer belt 1.

[0022] As shown in FIG. 2, the tension roller 202 is rotatably supported by bearing members 205 at both ends in the direction of the rotation axis. The bearing members 205 are attached to a frame 206 so as to be movable (slidable). Both bearing members 205 are biased by the compressive force of tension springs 207, which are compression springs serving as biasing means. The bearing members 205 are moved (slid) from the inner circumferential surface side to the outer circumferential surface side of the intermediate transfer belt 1 along the biasing direction of the tension springs 207. As a result, the tension roller 202 biases the intermediate transfer belt 1 from the inner circumferential surface side to the outer circumferential surface side of the intermediate transfer belt 1, thereby applying tension to the intermediate transfer belt 1. In addition, a regulating collar 208 for regulating the deviation of the intermediate transfer belt 1 is provided at the end of the rotation axis direction of the tension roller 202.

[0023] <Endless belt> Next, the intermediate transfer belt will be described. The intermediate transfer belt 1 is an endless belt, which is stretched around the drive roller 201, tension roller 202, etc. as described above and rotates in response to an image forming operation. In the intermediate transfer belt 1 of this embodiment, reinforcing members are provided on the outer peripheral surfaces of both ends in the width direction of the belt member (a direction substantially perpendicular to the belt conveying direction), and end-shaped protruding members are provided along the inner peripheral surfaces of both ends.

[0024] Here, the protruding member and the reinforcing member will be specifically described. Fig. 3 is a schematic perspective view showing a cross section of the end of the intermediate transfer belt 1 on the rear side as viewed from the front of the image forming apparatus main body. Note that Fig. 3 shows only the end of the intermediate transfer belt 1 on the rear side of the main body, but in this embodiment, the end on the front side of the main body has the same configuration (symmetrical with respect to the center in the width direction of the intermediate transfer belt 1).

[0025] As shown in Fig. 3, the intermediate transfer belt 1 of this embodiment has ribs 2, which are protruding members, on both ends in the width direction of the inner peripheral surface 1b of the endless belt member 1a. The ribs 2 of this embodiment have a rectangular cross section protruding from the inner peripheral surface 1b and are bonded along the inner peripheral surface 1b. As shown in the cross-sectional view of the vicinity of the end of the tension roller in Fig. 4, this rib 2 abuts against an end 208a of a regulating collar 208 provided at the end of the tension roller 202 in the rotation axis direction when the intermediate transfer belt 1 rotates, thereby regulating the belt deviation.

[0026] Further, a reinforcing tape 3 serving as a reinforcing member is provided on the outer peripheral surface 1c at both ends in the width direction of the intermediate transfer belt 1. In this embodiment, the reinforcing tape 3 is adhered along the outer peripheral surface 1c of the intermediate transfer belt 1.

[0027] 4, the rib 2 and the reinforcing tape 3 in this embodiment are disposed slightly inward from the edges of both ends in the width direction of the intermediate transfer belt 1. The rib 2 and the reinforcing tape 3 are disposed in positions where they at least partially overlap each other in the width direction of the intermediate transfer belt 1, and in this embodiment, they are disposed such that the area of ​​the rib 2 is located within the area of ​​the reinforcing tape 3 in the width direction.

[0028] The belt member 1a in this embodiment is made of a resin belt with a base layer of polyimide (PI), and has a tensile elastic modulus E of 18000 N / cm2 and a thickness of 0.08 mm. The thickness of the belt member 1a is preferably in the range of 0.02 mm to 0.50 mm. If the belt member 1a is too thin, it will not be able to obtain sufficient durability against wear, and if it is too thick, it will be difficult to bend around the drive roller 201, tension roller 202, and support rollers 203 and 204, resulting in deformation or breakage.

[0029] In addition, the rib 2 in this embodiment is made of a material mainly composed of urethane rubber. The reinforcing tape 3 is made of the same material as the belt member 1a. The materials of the intermediate transfer belt 1, the rib 2, and the reinforcing tape 3 are not particularly limited.

[0030] <Relationship between ribs and reinforcing tape> Next, a description will be given of the relationship between the rib 2 and the reinforcing tape 3. Fig. 5 is a perspective view of the intermediate transfer belt 1 showing the relationship between the rib 2 and the reinforcing tape 3.

[0031] As described above, the rib 2 is adhered to the end of the inner peripheral surface 1b of the intermediate transfer belt 1. Since the rib 2 is an end-shaped member, it is adhered from one end side and adhered along the inner peripheral surface 1b of the belt member 1a. However, due to variations in the parts of the belt member 1a and the rib 2 and variations in adhesion, it is difficult to provide the rib 2 continuously over the entire circumference in the longitudinal direction of the belt member 1a. For this reason, an opening W is formed where the rib 2 is not provided continuously along the longitudinal direction of the rib 2. Here, the opening W also includes a state in which the ends of the rib 2 are in contact with each other with no gaps.

[0032] In addition, the reinforcing tape 3 adhered to the end of the outer circumferential surface 1c of the belt member 1a is adhered by providing an overlapping portion X where the tape ends overlap each other, thereby ensuring the adhesion of the tape ends.

[0033] 6 is a graph showing the stress applied to the belt member 1a according to the thickness of the reinforcing tape 3 of this embodiment. As can be seen from this graph, the thickness of the reinforcing tape 3 in the overlapped portion of the reinforcing tape 3 is twice as thick as that in the non-overlapping portion, increasing the rigidity. Therefore, by providing the overlapped portion X, it is possible to suppress deformation of the belt member 1a in that portion.

[0034] In the present embodiment, the opening W in the circumferential direction of the intermediate transfer belt 1 is arranged so as to be located within the region of the overlapping portion X. Further, the length L1 of the opening W of the rib 2 in the circumferential direction of the intermediate transfer belt 1 and the length L2 of the overlapping portion X of the reinforcing tape 3 are configured such that L1 < L2. That is, the length L1 of the region where the ribs are not adhered from one end to the other end of the end-shaped rib 2 in the circumferential direction of the intermediate transfer belt 1 is set shorter than the length L2 of the region where two reinforcing tapes 3 are overlapped and adhered, and the opening W is arranged so as to be within the region of the overlapping portion X.

[0035] As described above, since the portion where the reinforcing tapes 3 are overlapped has higher rigidity than the non-overlapped portion, when the opening W of the rib 2 is located in this region, local deformation of the intermediate transfer belt 1 is suppressed when the opening W passes through the regulating collar 208, and the stress applied to the intermediate transfer belt 1 is reduced.

[0036] Here, if the length of the overlapping portion X of the reinforcing tape 3 is set longer than the length of the opening W of the rib 2, local deformation of the intermediate transfer belt 1 can be suppressed. Therefore, it is not necessary to set the length of the overlapping portion X of the reinforcing tape 3 long. Therefore, it is desirable that the length of the overlapping portion X of the reinforcing tape 3 is set to 1 / 4 or less of the circumferential length of the intermediate transfer belt 1.

[0037] As described above, by arranging the opening W of the rib 2 between the overlapping portions X of the reinforcing tapes 3, the stress applied to the intermediate transfer belt 1 can be reduced. That is, it becomes possible to provide an image forming apparatus that can suppress breakage of the intermediate transfer belt 1.

[0038] 〔Second Embodiment〕 Next, the intermediate transfer belt according to the second embodiment will be described. FIG. 7 is a perspective view of the intermediate transfer belt according to the second embodiment.

[0039] 7, a rib 2 having ends is adhered to both widthwise ends of the inner peripheral surface 1b of the belt member 1a, and an opening W is formed between both ends. In addition, end tapes 4 serving as belt reinforcing means are adhered to both widthwise ends of the outer peripheral surface 1c of the intermediate transfer belt 1 at positions facing the opening W of the rib 2.

[0040] The reinforcing tape 3 of this embodiment is adhered to the entire circumference of the belt member 1a in the circumferential direction, but the reinforcing tape 3 does not form an overlapping portion as in the above-mentioned embodiment. On the other hand, the end tape 4 is adhered to the belt member 1a and the reinforcing tape 3 so as to overlap the reinforcing tape 3 on the outer peripheral surface corresponding to the region where the opening W is provided in the circumferential direction, thereby forming the overlapping portion X. Therefore, in the region of the opening W, the reinforcing tape 3 and the end tape 4 overlap each other, increasing the thickness, and the rigidity of the portion increases, thereby suppressing the deformation of the intermediate transfer belt 1 at the rib opening W. As a result, the deformation of the intermediate transfer belt 1 is suppressed when the opening W of the rib 2 passes through the regulating collar 208, and the stress applied to the intermediate transfer belt 1 is reduced.

[0041] In this embodiment, as compared with the previous embodiment, it is not necessary to consider the position at which to start attaching the long reinforcing tape, and therefore the ease of assembly is improved. [Explanation of symbols]

[0042] S...Seat W …Opening X … overlapping part 1 ... Intermediate transfer belt 1a ... Belt member 1b…Inner peripheral surface 1c…Outer surface 2. Ribs 3. Reinforcement tape 4...End tape 100 ... Image forming device 101Y,101M,101C,101K...Image forming section 102 ... Photosensitive drum 103 ...Charging roller 104 ... exposure equipment 105 ...Developing device 106 ... Primary transfer roller 107 ... Sheet cassette 108 ...Transport roller 109 ... Secondary transfer roller 110 ... Fixing part 111...Discharge section 200 ... Intermediate transfer unit 201 ... Drive roller 202 ... tension roller 203, 204 ... Support roller 205 ... Bearing parts 206...Frame 207 ... tension spring 208 ...Regulation color

Claims

1. In an endless belt that transfers a toner image formed on an image carrier, An endless belt member; a reinforcing member provided along an outer peripheral surface of the belt member at an end in a width direction of the belt member; a protruding member having an end and provided along an inner peripheral surface of the belt member at an end in a width direction of the belt member; having the protruding member has an opening between both ends, and the reinforcing member has an overlapping portion where the reinforcing member overlaps in the circumferential direction of the belt member, When the distance of the opening in the circumferential direction is L1 and the distance of the overlapping portion is L2, a relationship of L1<L2 is satisfied, The position of the opening in the circumferential direction is located within the area of ​​the overlapping portion. An endless belt characterized by:

2. 2. The endless belt according to claim 1, wherein a distance between the overlapping portions in the circumferential direction is equal to or less than ¼ of a length of the belt member.

3. 2. The endless belt according to claim 1, wherein the overlapping portion is formed by overlapping a plurality of reinforcing members having different lengths.

4. 4. An image forming apparatus comprising the endless belt according to claim 1.

Images