JPH0535129A - Semiconductive endless belt - Google Patents

Abstract

PURPOSE:To improve durability with a simple construction 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 the central part of the body toward both ends. 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 central part toward both ends. The endless belt 9 obtd. in such a manner is put on two pieces of rollers and the elongation stresses acting on the respective parts in the transverse direction of the belt are measured. As a result, the stress is large in the central part 9b and is the smaller the nearer the both ends 9a, 9c. Then, a failure, crack, etc., are not generated in both ends even if this belt is used over a long period of time. In addition, the generation of wrinkles in the central part is decreased and image defects are eliminated.

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 above-mentioned intermediate transfer endless belt 17 has problems in durability and straightness of running at both left and right end portions of the belt. Although the intermediate transfer endless belt 17 is stretched around four rollers in FIG. 9, it is stretched between the two rollers 4 and 4 as shown in FIG. 8 to explain the above problem. Suppose In this case, if the intermediate transfer endless belt 17 is formed to have the same inner peripheral length over the entire surface, the left and right end portions 17 of the belt are formed.
Concentration stress of tension is generated in a and 17c, causing breakage, cracks, etc., which causes a decrease in durability. Further, even if the inner circumferential length of the belt is slightly varied, the running may be offset or the belt may be wrinkled. If the wrinkles are generated in the central portion 17b which is an image area, the image may be defective. Become. For this reason, reinforcement tapes are provided at both ends to increase the strength, and positioning guides are provided to prevent deviation, but in this case, the number of parts increases and the structure becomes complicated. To do.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a semiconductive endless belt having a simple structure, excellent durability, and free from uneven running or wrinkling. And

[0006]

In order to achieve the above-mentioned object, the semiconductive endless belt of the present invention has an inner peripheral surface which does not have its circumferential length extending from the central portion toward both ends. 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
Since the inner circumference of the belt is formed so as to increase steplessly from the center toward both ends, the above stress concentration is relieved at both ends of the belt where concentrated stress of tension occurs, resulting in damage or cracking of the belt. It is possible to prevent the occurrence of such as, and the durability is improved. In addition, the central portion of the belt has high adhesion to the rollers, which prevents the occurrence of running deviation and reduces wrinkles in the central portion, which is the image area, and prevents image defects from occurring. .. Furthermore, since only the shape of the belt is changed, the number of parts does not increase and the structure can be prevented from becoming complicated.

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 and 9c in the width direction is 200 mm, and the inner diameter D ₂ of the central portion 9b is 199.
8 to 198 mm (-0.1 to both ends 9a and 9c)
1.0%). 199.4 is desirable
~ 199 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. Depending on the case, after this mirror finish,
Further, the surface may be 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 thermal expansion coefficient of the resin pipe 3 is larger than the thermal expansion coefficient of the steel pipe 2.
The degree of diameter increase of the resin pipe 3 with respect to
As shown in FIG. 3, 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, 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, and at the same time, the inner peripheral surface of the thermoplastic sheet 1 is brought 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). As a result, the shape of the thermoplastic sheet 1 is the same as the outer peripheral surface of the drum-shaped resin pipe 3, that is,
The inner peripheral length increases steplessly from the central part toward both ends. 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 and the thermoplastic sheet 1 were wound. It is preferable to rotate the resin pipe 3 gently (1 rpm). In this way
The desired semiconductive endless belt 9 is obtained.

The semiconductive endless belt 9 thus obtained was spanned between two rollers, and the extension stress acting on each part of the belt 9 in the width direction was measured. The result is shown in FIG.
Shown in.

As is apparent from FIG. 7, the tensile stress acting on each of the above parts is large in the central part 9b, and both end parts 9a,
It can be seen that it becomes smaller as it gets closer to 9c. The dotted line shows the value when the elongation stress uniformly acts.

Even if the semiconductive endless belt 9 thus obtained is used for a long time while being stretched over both rollers (see FIG. 8), both ends 9a and 9c of the belt are damaged or cracked. Further, the occurrence of wrinkles in the central portion 9b was reduced, and image defects were eliminated. Further, there is an advantage that the outer peripheral surface of the semiconductive endless belt 9 is finished to be a mirror surface.

[0014]

As described above, according to the semiconductive endless belt of the present invention, even when the semiconductive endless belt is used by being stretched over a plurality of rollers, stress is generated at both ends of the belt where concentrated stress of tension occurs. Concentration is relieved, belt damage and cracks can be prevented, and durability is improved. In addition, in the central portion of the belt, the adhesion to the roller becomes large, and slight variations in the inner peripheral length are absorbed by this, which prevents the occurrence of running deviations and at the center of the image area. It is possible to reduce wrinkles in the area and prevent the occurrence of image defects. Further, since the shape of the belt is simply changed, the number of parts is not increased and the structure can be prevented from becoming complicated when the belt is incorporated in the electrophotographic copying machine.

[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 a diagram showing extensional stress acting on each portion of the semiconductive endless belt in the width direction.

FIG. 8 is an explanatory diagram showing a usage state of the intermediate transfer endless belt.

FIG. 9 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. A semiconductive material, characterized in that the inner peripheral surface of itself is formed such that its circumferential length increases steplessly from the central portion toward both ends. Endless belt.