JPH09242U - Paper transport device - Google Patents

Abstract

(57) Abstract: When a driven-side transport roller is brought into pressure contact with a drive-side transport roller, its pressure contact force is made constant and its pressure contact structure is simplified. A transport roller (11) on the driven side, which is in pressure contact with the transport roller (11) on the upper side of the drive side, is
It is rotatably penetrated by a coil-shaped spring 13 whose both ends are locked by the paper transport guide 15. Spring 13
In the middle of the process, the holding portions 15a provided upright in the vertical direction of the paper transport guide 15 sandwich both sides of the holding portion 15a to restrict the movement of the spring 13 in that direction, and the transport roller (1
It is possible to stabilize the pressure contact state to the 1) side.

Description

[Detailed description of the invention]

[0001]

[Technical field to which the invention belongs]

 BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet conveying device used in an image forming apparatus or the like, and more particularly to a sheet conveying device including a driven roller that is pressed against a driving roller to convey the sheet to a desired position.

[0002]

[Prior art]

 A sheet conveying device used in an image forming apparatus such as a copying machine is composed of a sheet conveying roller and a conveying guide which are composed of a pair of driving-side rollers and a driven roller which rotates with respect to the driving roller. A paper transport path including these paper transport rollers and a transport guide is provided from the paper feed unit to the paper discharge unit of the image forming apparatus, and the image formation processing is performed on the paper being transported.

For example, according to a copying machine, a photoconductor drum is arranged during sheet conveyance, and in the transfer step during the copying process, the sheet being conveyed is brought into contact with the surface of the photoconductor drum to be formed on the surface of the photoconductor. The electrostatic toner image is transferred onto the paper. In a copying machine having such a configuration, in order to transfer the electrostatic toner image formed on the surface of the photoconductor drum to the correct position on the paper, the conveyance of the paper is accurately synchronized with the rotation of the photoconductor drum. At the same time, the capacity of the paper transport path must be improved.

On the other hand, in order to easily remove the 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 conveyance path is provided at the boundary between the upper and lower units. The formed one is put to practical use.

In such an image forming apparatus, the pair of rollers in the sheet conveying path are separated into upper and lower parts when the upper unit is opened upward.

[0006]

As described above, according to the conventional sheet conveying apparatus, the shaft mounting positions of the upper and lower rollers of the sheet conveying roller are completely fixed to the upper unit and the lower unit. Therefore, depending on the open / close state of the upper and lower units, the positional relationship of these rollers and the pressure contact force of these rollers are not constant, and the capacity of the paper transport path is not stable, which easily causes jams. However, there was a problem that the transfer position of the electrostatic toner image was not constant.

Further, the pair of upper and lower conveying rollers has one as a driving roller and the other as a driven roller which is driven to rotate by being pressed against the driving roller, and the driven roller also has the same axis on the same axis as the driving roller. As described above, the driving roller is not pressed against the driving roller with a constant pressing force. Moreover, the pressure contact structure for making the pressure contact state uniform is extremely complicated.

In view of the above-mentioned point, the present invention stabilizes the pressure contact force of the driven side roller with respect to the drive roller, thereby improving the transportability (conveyance ability), and at the same time, simplifying the structure for pressure contact. The purpose is to

[0009]

[Means for Solving the Problems]

 A sheet conveying apparatus for achieving the above object of the present invention is provided with a pair of rollers for conveying a sheet, one of the rollers is driven, the other is driven, and the driven side is brought into pressure contact with the driving side roller. In the sheet transporting device configured as described above, the driven-side roller is rotatably supported with a coiled spring as an axis, and a holding portion is provided so as to sandwich both sides of the spring.

According to this structure, the driven roller can be brought into pressure contact with the driving roller individually with a constant pressure by the action of the spring. Also, by providing the holding parts so as to sandwich both sides of the spring, even if the shaft is a spring, the spring can maintain a good pressure contact state with the driving side roller, which improves transportability and at the same time. The structure becomes very simple.

[0011]

[Embodiment of the invention]

 An embodiment of a sheet conveying device according to the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing a roller on one driven side of a pair of conveying rollers constituting a sheet conveying apparatus according to the present invention, and a roller pressed against a driving side roller, and FIGS. FIG. 2 is a view showing the schematic structure of the inside of a copying machine showing a state in which the paper conveying device of the present invention is applied to the copying machine. FIG. 2 is an opening in which the copying machine is divided along the paper conveying path so as to be opened and closed vertically. Fig. 3 shows the closed state.

The copying machine shown in FIGS. 2 and 3 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 be rotated by this support P.

The upper unit B includes a replacement unit 5 in which the photosensitive drum 1, the primary charger 2, the cleaner unit 3, and the separation roller 4 are integrated. The replacement unit 5 can be attached to and detached from the upper unit B by an attachment / detachment mechanism (not shown). An optical system 6 including a light source 60 and a converging light transmission body 61 is arranged above the exchange unit 5. Further, on the right side of the photoconductor drum 1, a developing device 7 having a first developing section 70 and a second developing section 71 is rotatably provided. The first developing device 70 and the second developing device 71 contain toners of different colors. By rotating the developing device 7, it is possible to make one of the developing portions face the photosensitive drum 1. Further, a paper transport guide 8 is provided in front of the photosensitive drum 1, a timing roller (hereinafter referred to as a PS roller) 9 and a transport roller 11 are provided on the guide. It is installed.

A sheet conveying guide 15 is provided on the upper right end of the lower unit A, and a lower PS roller 16 facing the PS roller 9 of the upper unit B and a conveying roller 11 are provided on the sheet conveying guide. The lower transport roller 12 is provided. On the left side of the PS roller 16, when the upper and lower units A and B are in the mounted state (closed state in FIG. 3), a transfer device 17 facing the photosensitive drum 1 is provided. A conveyance guide 18 for guiding the paper is provided. Further, a fixing roller 19 is arranged on the left side of the conveyance guide 18, and a paper discharge detection switch 20 for detecting the paper discharged from the fixing roller 19 is arranged on the left side thereof. Further, a paper feed cassette 21 is detachably provided at the bottom of the lower unit A, and a paper feed roller 22 is provided at the paper feed portion. The paper fed from the paper feed cassette 21 by the paper feed roller 22 is transferred to the transfer portion of the photosensitive drum 1 by the above-mentioned transfer rollers 11 and 12, the above-mentioned paper transfer guides 8 and 15, and the PS rollers 9 and 16. Be transported.

The paper transport guides 8, 15 and 18 are formed on the boundary surface between the upper and lower units A and B as shown in the drawing, and form a paper transport path together with the paper transport guides. The upper rollers 11 and 9 of the transport roller and the PS roller are attached to the upper unit B, respectively.

FIG. 1 is a perspective view showing a mounting structure of a lower carrying roller 12 which is a driven side roller of a carrying roller constituting a paper carrying device according to the present invention. The carrying roller 12 is rotatably provided so as to be pressed against the upper carrying roller 11, and is attached to the lower unit A as shown in the drawing.

The lower transport roller 12 is composed of a total of four rollers 12 a to 12 d corresponding to the upper transport roller 11 on the drive side in parallel with the rotation axis of the photosensitive drum 1. Coil-shaped springs 13a and 13b individually penetrate through the centers of the rollers 12a and 12b, and both ends of the springs 13a and 13b are formed on the sheet conveying guide 15 by supporting portions 14a, 14b, 14c and 14d. It is locked to. With such a structure, the rollers 12a and 12b can rotate around the springs 13a and 13b and can move by the action of the springs.

The rollers 12c and 12d are rotatably supported by a single coil-shaped spring 13c. The rollers 12c and 12d can also rotate about the spring 13c and can move at the same time.

In this embodiment, in this way, among the pair of conveying rollers 11 and 12, a plurality of lower conveying rollers 12 that are not drive rollers are supported by respective springs 13 (13a to 13c). ing. Therefore, when the upper and lower units A and B are mounted, even if the position of the upper transport roller 11 shifts due to some reason, the shift is absorbed by the spring 13. That is, the position and contact pressure of the contact portions of the upper and lower transport rollers 11 and 12 are always constant. As a result, it is possible to suppress variations in the carrying force of the carrying rollers, and it is possible to carry out stable paper carrying.

As shown in FIG. 1, both ends of the coil-shaped spring 13 are locked to the support portion 14, and in the middle thereof, as shown in FIG. An upright holding portion 15a is provided. The holding portion 15a is configured so that it can hold the shaft formed by the above-described spring 13 so as to sandwich it from both sides as shown in FIG.

Therefore, it is apparent from FIG. 1 that the spring 13 is restricted from freely moving to both sides sandwiched by the holding portion 15a. As a result, the conveying roller 12 can be pressed into good contact with the driving side conveying roller 11, and at the same time, as described above, the free movement to both sides is restricted, so that the conveying roller 11 can be kept in pressure contact with the conveying roller 11 during conveyance. It maintains good quality and enables more stable paper transportation.

Moreover, by providing the holding portion 15a as shown in FIG. 1, the rotatable transport roller 12 provided penetrating the spring 13 is also restricted from moving in the axial direction of the spring 13, and the transport roller 11 Therefore, it will be pressed in a stable state at a predetermined position.

As with the transport rollers 11 and 12, also on the PS rollers 9 and 16 side, the driven roller side other than the drive roller can be rotatably supported by a spring as shown in FIG.

[0024]

[Effect of the invention]

 According to the paper transporting device of the present invention, the roller that is not the driving side of the transporting roller is rotatably provided on the shaft of the coil-shaped spring, so that the driving roller can be constantly pressed with a constant pressure. Even if the shaft is a spring, the movement of the paper is limited, so that the paper can be conveyed easily and stably.

Further, the structure therefor becomes very simple.

[Brief description of drawings]

FIG. 1 is a perspective view showing a mounting structure of a driven-side roller which constitutes a sheet conveying device according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing an outline of the inside of a copying machine in which the paper transporting device of the present invention is applied to a copying machine that can be opened and closed up and down, and is a diagram showing an open state.

FIG. 3 is a cross-sectional view showing an internal schematic structure of a copying machine in a closed state in which the paper transporting device of the present invention is applied to a copying machine that can be opened and closed up and down.

[Explanation of symbols]

 11 Upper Transport Roller (Drive Side Roller) 12 Lower Transport Roller (Driven Roller) 13 Coiled Spring (Shaft) 14 Supporting Part 15 Transport Guide 15a Holding Part

Claims (1)

[Utility model registration claims] 1. A sheet conveying device configured to provide a pair of rollers for conveying a sheet, drive one of the rollers, and make the other of the rollers driven, and press the driven side against a roller on the driving side. A sheet conveying apparatus, wherein the driven roller is rotatably supported by a coiled spring as an axis, and holding portions are provided so as to sandwich both sides of the spring.