JPH0452204Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial field of application> The invention consists of a lower unit and an upper unit rotatably supported by the lower unit. An image forming apparatus that forms a conveyance path, has a pair of paper conveyance rollers, one of which is provided in an upper unit, and the other is provided in a lower unit, and one of the paper conveyance rollers is pivotally supported by a spring. Related to paper conveyance rollers.

<Prior Art> A paper transport device used in an image forming apparatus such as a copying machine is composed of a paper transport roller including a pair of rollers, a transport guide, and the like. A paper transport path including these paper transport rollers and transport guides is disposed from a paper feed section to a paper discharge section of the image forming apparatus, thereby forming an image on the paper being transported. For example, in a copying machine, a photoreceptor drum is placed in the paper transport path, and the paper being transported is brought into contact with the surface of the photoreceptor drum in the transfer step of the copying process, and the electrostatic toner image formed on the surface of the photoreceptor is transferred. Transfer it onto paper. In a copying machine with such a configuration, in order to transfer the electrostatic toner image formed on the surface of the photoreceptor drum to the correct position on the paper, paper transport is accurately synchronized with the rotation of the photoreceptor drum, and the paper transport is We also need to improve road capacity.

On the other hand, in order to make it easier to remove jammed paper, the image forming apparatus is divided into upper and lower units, the upper unit is rotatably supported by the lower unit, and a paper transport path is formed at the boundary between the upper and lower units. It has been put into practical use. In such an image forming apparatus, one of the pair of paper conveyance rollers in the paper conveyance path is provided in the upper unit, and the other is provided in the lower roller. However, in conventional image forming apparatuses with such a structure, the mounting positions of the upper and lower roller shafts of the paper transport roller are completely fixed to the upper and lower units, so that the mounting positions of the upper and lower rollers vary depending on the open/closed state of the upper and lower units. Therefore, the positional relationship of these rollers and the pressure contact force of these rollers are not constant, and the performance of the paper conveyance path is not stable, making it easier to cause jams, and the transfer position of the electrostatic toner image is not constant. It was hot.

Therefore, conventionally, the position and pressure relationship between the upper and lower paper transport rollers was always constant, and in order to prevent variations in paper transport capacity,
A paper conveyance roller for an image forming apparatus has been proposed in which one roller of the paper conveyance roller is pivotally supported by a spring.

<Problems to be solved by the invention> However, as shown in FIG. 4, the paper conveyance roller of the conventionally proposed image forming apparatus has a spring 3 passed through the shaft hole 2 of the upper roller 1, and both ends of the spring 3 are connected to the main body. The upper roller 1 is fixed to the stepped portion 5 and cut-and-raised portion 6 of the paper guide 4 on the upper unit side to support the upper roller 1, and the upper roller 1 is attached to the paper guide 8 on the lower unit side using the biasing force of the spring 3. It is elastically pressed against the provided lower roller 7. In particular, in order to convey the paper along the reference guide 9 side, it is preferable to arrange the upper roller 1 as close to the reference guide 9 side as possible. Further, in order to obtain a stable conveying force in the longitudinal direction of the roller, the roller must have a certain length.

However, according to the above configuration, there is not enough space for fixing both ends of the spring 3 for supporting the upper roller 1, and as a result, the ends of the spring 3 are bent in a convex shape, and the upper roller 1 is moved in the direction of the arrow in the figure. There is a problem that the lower roller 7 is not evenly pressed against the lower roller 7 due to the effect of the lower roller 7.

An object of the present invention is to provide a paper conveying roller for an image forming apparatus that has a simple structure and eliminates the problems of the conventional apparatus.

<Means for Solving the Problems> The present invention is characterized in that a concave portion centered on the shaft hole of the roller is formed on the side surface of the paper conveyance roller which is supported by a spring.

<Function> According to the present invention, a concave portion centered on the shaft hole of the roller is formed on the side surface of the paper conveyance roller which is supported by a spring, so that there is a gap between the open end of the shaft hole of the roller and the fixed portion of the spring. Since a sufficient space can be taken, no unnatural bending force is applied to the space, and therefore, the roller can be evenly pressed against the other roller.

<Embodiment> FIG. 1 shows a schematic structural diagram of a copying machine which is an embodiment of the present invention, and in particular, this figure shows the state when the upper and lower units are opened.

The copying machine of this embodiment is composed of a lower unit A and an upper unit B. The upper unit B is pivotally supported by the lower unit A at a fulcrum P, and can rotate about this fulcrum P.

The upper unit B includes an exchange unit 15 in which a photosensitive drum 10, a primary charger 11, a cleaner unit 13, and a separation roller 14 are integrated. This exchange unit 15 is detachable from the upper unit B by a detachable mechanism (not shown). An optical system 18 consisting of a light source 16 and a convergent light transmitter 17 is arranged above the exchange unit 15. Further, on the right side of the photosensitive drum 10, a developing device 21 including a first developing section 19 and a second developing section 20 is rotatably provided. The first developing section 19 and the second developing section 20 each contain toners of different colors. Developing device 21
By rotating , any one of the developing sections can be opposed to the photosensitive drum 10 . Further, in front of the photoreceptor drum 10, a paper conveyance guide 22,
A timing roller (hereinafter referred to as PS roller) 23 and a paper feed roller 24 are provided on this guide, and a manual paper feed detection switch 25 is also attached to the right end of the upper unit B.

At the upper right side of the lower unit A is a paper conveyance guide 26, and on this paper conveyance guide 26 is a lower PS opposite to the PS roller 23 of the upper unit B.
A lower paper feed roller 28 facing the roller 27 and the paper feed roller 24 is provided. A transfer device 29 is provided on the left side of the PS roller 27, which faces the photosensitive drum 10 when the upper and lower units A and B are installed, and a conveyance guide 30 for conveying the transfer paper is provided on the left side of this transfer device 29. Further, a fixing roller 31 is disposed on the left side of the conveyance guide 30, and a paper discharge detection switch 32 for detecting a paper discharged from the fixing roller is further disposed on the left side thereof. Further, a paper feed cassette 33 is detachably attached to the bottom of the lower unit A, and a paper feed roller 34 is provided in the paper feed section. Paper cassette 33
The paper fed by the paper feed roller 34 from
2, 26, and the PS rollers 23, 27 transport the photosensitive drum 1 to the transfer section.

The paper conveyance guides 22, 26, and 30 are formed at the interface between the upper and lower units A and B, as shown, and together with these paper conveyance guides form a paper conveyance path. The upper rollers 24 and 23 of the paper feed roller and the PS roller are attached to the upper unit B, and the lower units 28 and 27 are attached to the lower unit A, respectively.

FIG. 2 is a detailed view of the upper paper feed roller 24 and the lower paper feed roller 28. In particular, on one side of the upper paper feed roller 24, as shown by the dotted line in the figure, there is a center hole 2 in the shaft hole 2 of the roller. A recess 34 having a predetermined depth is formed.

According to this configuration, the distance between the open end 35 of the shaft hole 2 of the roller 24 and the fixed portion 5 of the spring 3 can be widened. Therefore, since the spring 3 does not bend unnaturally, the upper roller 24 can be evenly pressed against the lower roller 28. In particular, as shown in FIG. 3, if recesses are formed on both sides of the upper roller 24, the pressure distribution on both sides of the roller can be made more uniform.

<Effects> As described above in detail, according to the present invention, since the concave portion is formed on the side surface of the paper conveyance roller supported by the spring, a large space can be secured in the spring fixing portion. Therefore, no unnatural force is applied to the spring, and therefore the spring can be brought into uniform pressure contact with the other roller.

[Brief explanation of the drawing]

FIG. 1 is a schematic structural diagram of a copying machine implementing the present invention, FIG. 2 is a detailed diagram of a paper conveyance roller, FIG. 3 is a diagram showing another embodiment, and FIG. 4 is a diagram showing a conventional example. . 22 and 26 are paper conveyance guides, 24 and 28 are paper conveyance rollers, and 34 is a recessed portion.

Claims (1)

[Claims for Utility Model Registration] Consisting of a lower unit and an upper unit rotatably supported by the lower unit, a paper conveyance path is formed at the interface between these upper and lower units, and a pair of In an image forming apparatus in which one of paper transport rollers consisting of rollers is provided in an upper unit and the other is provided in a lower unit, and one of the paper transport rollers is pivotally supported by a spring, the roller is pivotally supported by the spring. 1. A paper conveyance roller for an image forming apparatus, characterized in that a concave portion is formed on a side surface of the paper conveyance roller, the center of which is a shaft hole of the roller.