JPH0535130A - Semiconductive endless belt - Google Patents

Abstract

PURPOSE:To allow inexpensive production and to obviate the generation of biasing and wrinkling in traveling by continuously increasing the length in the circumferential direction of the inner peripheral surface of the belt from both ends of the body toward the central part. CONSTITUTION:The semiconductive endless belt 9 consisting of a thermoplastic sheet is formed to such a shape that the inside diameter D2 of the central part 9b is set at -0.1 to -1.0% size with respect to the inside diameter D1 of both right and left ends 9a, 9c in a transverse direction. Namely, the belt is so formed that the length in the circumferential direction of the inner peripheral surface of the belt itself increases continuously from the ends toward the central part. The biasing of the endless belt 9 obtd. in such a manner does not arise and the generation of wrinkles in the central part 9b decreases to eliminate image defects even if such belt is used over a long period of time in the state of putting the belt on two pieces of rollers formed to a drum shape. Further, an advantage lies in that the outer peripheral surface of the semiconductive endless belt 9 can be finished to a specular surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductive endless belt such as an intermediate transfer belt, a photosensitive belt and a contact developing sleeve used in various OA equipment such as an electrophotographic copying machine.

[0002]

2. Description of the Related Art An electrophotographic copying machine, particularly a full-color electrophotographic copying machine, temporarily transfers a full-color toner image formed on a photosensitive member onto an outer peripheral surface of an intermediate transfer endless belt made of a thermoplastic resin endless belt. It is designed to be re-transferred to copy paper. Such a full-color electrophotographic copying machine is usually constructed as shown in FIG. That is, the electrophotographic copying machine includes an optical device 12 that guides reflected light of a document 11, a filter 13 that separates the reflected light of the document into three primary colors of red, green, and blue, and a belt-shaped photoconductor having photoconductivity. 14, a developing device 15, and a photoconductor 14
Intermediate transfer endless belt 17 for temporarily transferring the toner image formed on the outer peripheral surface of the copy paper 16 before copying the toner image onto the copy paper 16.
And a fixing device 18. More specifically,
A charging charger 19 is provided in the vicinity of the start end side portion of the belt-shaped photoconductor 14 having photoconductivity, and three developing portions 15a to 15c are provided in the middle part of the photoconductor 14. The belt-shaped photoconductor 14 is charged by the charging charger 19 and then exposed by the reflected light of the document projected from the optical device 12, and an electrostatic latent image is formed thereon. In this case, in the projection path of the optical device 12 for projecting the reflected light of the original onto the photoconductor 14, the filter 13 for separating the reflected light of the original into the three primary colors of red, green and blue as described above.
The primary color lights separated by the above are sequentially guided to the belt-shaped photoconductor 14 in the order of, for example, red is first, and then green, and each electrostatic latent image is formed. The developing device 15 includes three developing units 15a, 15b, and 15c so as to correspond to the above-mentioned three types of primary colors, and respectively stores toners of three types of colors corresponding to the above-described separated three primary colors. .. Then, the latent image formed by the color-separated light is color-developed with the toner corresponding to the color. That is, a colored toner image is formed for each color by the toners of the above three types of colors, and this is the primary transfer roller 20.
By this action, the toner images are sequentially transferred to the outer surface of the intermediate transfer endless belt 17, and a full-color toner image is formed on the intermediate transfer endless belt 17. As described above, the copying machine sequentially transfers the colored toner image formed for each color onto the copy paper 16,
An intermediate transfer endless belt 17 that does not form a colored toner image on the copy paper 16 and does not expand or contract due to humidity or the like.
First, a colored toner image is formed. Then, the toner image is transferred onto the copy paper 16 supplied from the paper cassette 21.
Then, it is retransferred by the action of the secondary transfer roller 22. The retransferred full-color toner image is sent to the fixing device 18 as the copy paper 16 is conveyed and fixed, and the copy paper 16 on which the toner image has been fixed is sent out from the copying machine as indicated by an arrow. The toner remaining on the intermediate transfer endless belt 17 is collected by the cleaning blade 25 of the cleaning device 24 after the transfer and is ready for the next transfer. Two
3 is a conveyor belt.

[0003] Such an intermediate transfer endless belt 17, by an extrusion molding method, polycarbonate (PC), polypropylene a dispersion of (PP) conductive material such as carbon black in thermoplastic resin such as, 10 ⁸ to 10 It is obtained by extrusion molding into a semi-conductive endless belt-shaped sheet (cylindrical sheet) of ¹¹ Ωcm, and the inner circumferential surface has the same circumferential length (inner circumferential length) over the entire length.

[0004]

However, the intermediate transfer endless belt 17 has a problem in the straight running property of the belt. The intermediate transfer endless belt 17 is a roller (see FIG.
In this case, if the intermediate transfer endless belt 17 is formed to have the same inner circumferential length as a whole, in this case, the inner circumferential length of the belt may vary slightly. Even if the wrinkles occur in the center of the image area due to running deviation or wrinkling of the belt, the image becomes defective. For this reason, rubber positioning guides are fixed to the inner surfaces of both ends along the circumference with double-sided adhesive tape, and these guides are fitted into the guide grooves formed in the circumferential direction at the both ends of each roller to prevent deviation. Although it has been prevented, in this case, there is a problem that the cost is increased due to post-processing and the fixing force of the adhesive tape is weak, so that the guide itself is biased and the position shift still occurs during traveling. Remain.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a semiconductive endless belt which can be manufactured at a low cost and does not cause uneven running or wrinkling.

[0006]

In order to achieve the above-mentioned object, the semiconductive endless belt of the present invention has an inner peripheral surface that does not move as its circumferential length goes from both ends toward the central part. The structure is such that it is formed so as to increase in stages.

[0007]

That is, the semiconductive endless belt of the present invention is
The inner circumference of the belt is formed so as to increase steplessly from both ends toward the center, so by stretching this belt around a drum-shaped roller, the tension is kept uniform over the entire belt. It is possible to prevent the deviation of the running of the belt from occurring. Moreover, since only the shape of the belt is changed, the post-processing can be omitted and the belt can be manufactured at low cost.

Next, the present invention will be described in detail based on embodiments.

[0009]

1 shows an embodiment of the present invention. In the figure, 9 is a semiconductive endless belt made of a thermoplastic sheet, and the inner diameter D ₁ of the left and right end portions 9a, 9c in the width direction is 200 mm, and the inner diameter D ₂ of the central portion 9b is 200.
2-202mm (+0.1+ for both ends 9a, 9c)
1.0%). 200.6 is desirable
~ 201 mm (+0.3 ~ + for both ends 9a, 9c
0.5%). Further, the thickness of the belt is set to 100 to 200 μm and the width L is set to 350 mm. Polypropylene (PP), polycarbonate (PC) or the like is used as the material of the thermoplastic sheet. Moreover, PP has a coefficient of thermal expansion of 0.9 to 1.5 × 10.
^-4 (5 to 10 times that of metal) and PC is 0.75 x 10
^-4 (4 to 5 times that of metal).

The semiconductive endless belt 9 is manufactured, for example, as follows. That is, first, a cylindrical sheet (made of a thermoplastic resin) extruded into an endless belt by an extrusion molding machine (not shown) is axially moved as shown in FIG. 2 and FIG. The resin pipe 3 (see FIG. 4) made of fluorine resin (Teflon) having a substantially drum-shaped cross section is covered with the resin pipe 3 and inserted into the steel pipe 2.
The inner peripheral surface of the steel pipe 2 is mirror-finished by honing. In some cases, after this mirror-finishing, the surface may be further coated with silicon, polyimide, polyether sulfone or the like to prevent the molten thermoplastic resin from adhering to the surface. Then, the whole is put in an oven or the like and uniformly heated. As a result, the thermoplastic sheet 1 is softened, and at the same time, the steel pipe 2 and the resin pipe 3 are expanded. At the time of this expansion, the coefficient of thermal expansion of the resin pipe 3 is larger than the coefficient of thermal expansion of the steel pipe 2, so that the diameter of the resin pipe 3 relative to the steel pipe 2 is increased,
As shown in FIG. 5, the outer peripheral surface of the softened thermoplastic sheet 1 is pressed against the inner peripheral surface of the steel pipe 2 by the outer peripheral surface of the resin pipe 3. Therefore, at the same time when the mirror surface of the inner peripheral surface of the steel pipe 2 is transferred and formed on the outer peripheral surface of the thermoplastic sheet 1,
The inner peripheral surface of the thermoplastic sheet 1 comes into close contact with the outer peripheral surface of the resin pipe 3. Then, it is cooled and the thermoplastic sheet 1 is removed from the steel pipe 2. In this case, if the temperature of the steel pipe 2 is too high, peeling marks remain on the outer peripheral surface of the thermoplastic sheet 1. At this time, if the cooling rate of the steel pipe 2 is set to be higher than that of the thermoplastic sheet 1, the peeling traces do not remain, so it is preferable to cool the steel pipe 2 by blowing air around it. Further, at the time of the cooling, the thermoplastic sheet 1 and the resin pipe 3 are reduced in diameter while being in close contact with each other, and the state returns to the initial state (see FIG. 6). Thereby, the thermoplastic sheet 1
Has the same shape as the outer peripheral surface of the drum-shaped resin pipe 3, that is, the inner peripheral length increases steplessly from both end portions toward the central portion. Then, air is blown between the thermoplastic sheet 1 and the resin pipe 3 to float the thermoplastic sheet 1 from the outer peripheral surface of the resin pipe 3 and remove it.
During the process of blowing air around the steel pipe 2 and the process of removing the thermoplastic sheet 1 while blowing air between the thermoplastic sheet 1 and the resin pipe 3, the steel pipe 2
Then, it is preferable that the resin pipe 3 around which the thermoplastic sheet 1 is wound is rotated gently (1 rpm). In this way, the target semiconductive endless belt 9 is obtained.

As shown in FIG. 7, even if the semiconductive endless belt 9 thus obtained is used for a long time in a state of being stretched over both rollers, the belt is not biased.
Moreover, the occurrence of wrinkles in the central portion 9b is reduced, and the image defect is eliminated. Further, there is an advantage that the outer peripheral surface of the semiconductive endless belt 9 is finished to be a mirror surface.

[0012]

As described above, in the semi-conductive endless belt of the present invention, the tension can be kept uniform over the entire belt by straddling the semi-conductive endless belt on the drum-shaped roller, so that the belt runs. There is no deviation of
Moreover, since only the shape of the belt is changed, the post-processing can be omitted and the belt can be manufactured at low cost.

[Brief description of drawings]

FIG. 1 is a perspective view of a semiconductive endless belt showing an embodiment of the present invention.

FIG. 2 is a perspective view showing an apparatus for manufacturing the semiconductive endless belt.

FIG. 3 is a sectional view of the manufacturing apparatus.

FIG. 4 is a perspective view of a resin pipe used in the manufacturing apparatus.

FIG. 5 is a cross-sectional view showing a heated state in the manufacturing apparatus.

FIG. 6 is a cross-sectional view showing a cooled state in the manufacturing apparatus.

FIG. 7 is an explanatory diagram showing a usage state of the intermediate transfer endless belt.

FIG. 8 is a configuration diagram of a full-color copying machine incorporating an intermediate transfer endless belt.

[Explanation of symbols]

 1 Thermoplastic Sheet 2 Steel Pipe 3 Resin Pipe 9 Semi-Conducting Endless Belt 9a Its End 9b Its Center 9c Its End

Claims (1)

Claim: What is claimed is: 1. An inner peripheral surface of itself is formed so that its circumferential length increases steplessly from both end portions toward the central portion and is semiconductive. Endless belt.