JPH0680467B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming apparatus that forms an image on a conveyed sheet.

Conventionally, in this type of image forming apparatus, for example, a conductive member in the vicinity of the transfer portion must be electrically separated from the frame ground at the time of image formation in order to prevent transfer omission. In the past, these members remained separated from the frame ground even when the apparatus was separated and opened when the image was not formed. Therefore, during a jam treatment or the like which is performed after the device is divided and released, static electricity charged on the human body or the like may fly to the conductive member and cause malfunction of the device or destruction of elements.

Therefore, the present invention eliminates the above-mentioned drawbacks of the conventional example, and enables stable image formation against electrostatic noise even when electrostatic noise may occur in the device during jam processing performed by dividing the device. The purpose is to provide a device.

Hereinafter, specific embodiments of the present invention adapted to a resist unit will be described with reference to the drawings.

FIG. 1 is a vertical cross-sectional view of the vicinity of the transfer portion of the image forming apparatus,
In the figure, 1 is an image bearing member such as a photosensitive member, 2 and 3 are transfer guides for guiding sheet conveyance, 4 is a registration roller for timing of sheet feeding, 5 is a lower guide for guiding the sheet, and A is a guide.
Represents a transfer unit, and B represents a resist unit.

2 is a perspective view showing a state in which the resist unit B shown in FIG. 1 is engaged with the lower guide 5, 11 is a resist chassis, 12 is an upper guide member, 13 is a stopper member, and 14 is a stopper member.
Is a pressing roller, 15 is a resist shutter, 16 is a pressing spring, and the resist chassis 11 is fixed to the main body chassis, and accordingly, is electrically connected to a frame ground as a ground member.

Here, the presser roller 14 is positioned by being pressed by the pressurizing spring 16 acting around the fulcrum 12a to a downward force and being pressed against the rising portion 5a of the lower guide 5.

On the other hand, the upper guide 12 has a structure in which it can rotate around a fulcrum 12a as a fulcrum. In the state shown in FIGS. 2 and 3, the folded portion 12b of the upper guide 12 hits the guide 5 by its own weight and the lower guide 5, the distance from 5 is constant, and the lower end surface of the bent portion of the stopper 13 fixed to the upper guide 12 in this state
13a is separated from the contact surface 11a of the resist chassis 11, so that the upper guide 12 is separated from the frame ground.

Next, as shown in FIG. 4, when the resist unit B is released from the lower guide 5, the pressing roller 14 receives a force in the counterclockwise direction in the drawing by the pressing spring 16, so that the upper guide 12 receives the force. Also rotate counterclockwise in the figure with the fulcrum 12a as the fulcrum,
Finally, the lower end surface 13a of the bent portion comes into contact with the contact surface 11a of the resist chassis 11 to stop the rotation.

For this reason, when the registration unit B is released from the lower guide 5 (Fig. 4), the upper guide 12 uses the registration chassis 11
It is electrically connected to and then drops to the frame ground and becomes the same potential as the frame ground.

Although the above embodiment has described only the resist unit B as an example, the target conductive member is the resist unit B.
The present invention is not limited to the above, but can be applied to all members that are separated from the frame ground when forming an image and that conducts to the frame ground when the device is opened.

As described above, the conductive member inside the apparatus, which is separated from the frame ground during image formation, is electrically connected to the frame ground when the apparatus is opened. It becomes stable against electric noise.

[Brief description of drawings]

1 is a sectional view of the vicinity of a transfer portion of the image forming apparatus, FIG. 2 is a perspective view of a resist unit showing an embodiment of the present invention, FIG. 3 is a view taken in the direction of arrow C in FIG. 2, and FIG. FIG. 6 is a partial front view showing the state of the resist unit when the device is opened. 1 is an image carrier, 5 is a lower guide, 12 is an upper guide, A is a transfer portion, and B is a resist unit.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Junichi Kimizuka 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-54-150130 (JP, A) JP-A-57 -181571 (JP, A) JP-A-54-9932 (JP, A) JP-A-57-124360 (JP, A) JP-A-57-185448 (JP, A) JP-B-59-5890 (JP, B2) )

Claims (1)

[Claims] 1. An image bearing member carrying an image to be transferred onto a sheet, and an image bearing member for transferring the image carried by the image bearing member onto a sheet,
A conductive guide member for guiding the sheet to the image carrier, the guide member being movable to a first position for guiding the sheet and a second position for not guiding the sheet, and being in the first position. The image forming apparatus is configured to be electrically separated from the ground member when the second position and to be electrically connected to the ground member to have the same potential as the ground member when in the second position.