JPH0646321B2 - Electrophotographic copying machine with pressure transfer paper guide - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electrophotographic copying machine, and more particularly to a copying machine having a pressing type transfer paper guide plate.

-Background of the Invention-In an electrophotographic copying apparatus, an original image is recorded as a latent image on a charged photoconductor drum, the latent image is toner-developed by a developing device, and the transfer is carried along the photoconductor surface. A transfer electrode imparts a charge having a polarity different from that of the toner particles to the paper to attract and transfer the toner particles onto the transfer paper, and then the transfer paper is separated from the photoconductor to fix the toner.

Here, the transfer paper is conveyed along the transfer paper guide plate to the surface of the photoconductor drum, and the structure of the transfer paper guide plate is a fixed type shown in FIG. There is a pressing type shown in B). In FIG. 2A, the carry-out port of the fixed guide plate 2 faces the peripheral surface of the photosensitive drum 1, and the leading end of the transfer paper 4 sent from the feed roller 3 is contact-adsorbed to the photosensitive drum 1 and transferred. Electrode 5, separation electrode 6
Moved to the side.

In contrast to the fixed type, in the pressing type shown in FIG. 2B, the guide plate 7 is rotatably supported by the shaft 8, and the tip end of the guide plate 7 is the pressing spring 9 and the circumference of the photosensitive drum 1. Pressed on the surface. Here, a spacer 7A is provided at the tip of the guide plate 7 so as to contact the surface of the photoconductor drum 1 at both ends of the photoconductor drum 1 which are non-image parts. A small gap is secured between the drum 1 and the drum 1.

The above-mentioned pressing type transfer paper guide has an advantage that the gap between the transfer paper and the photoconductor drum surface can be made smaller than that of the fixed type guide, so that the contact and suction to the drum surface can be ensured. Further, by pressing down the guide plate 7 when removing the photosensitive drum 1 or the cartridge thereof, the drum surface can be easily removed without being damaged by the tip end portion of the guide plate.

-Problems to be Solved by the Invention- In a copying apparatus including a conventional pressing type transfer paper guide plate, the transfer paper guide plate 7 is usually made of a conductive member (metal). The transfer paper 4 is
Its electrical resistance changes. Therefore, when the transfer paper 4 contacts the surface of the photosensitive drum 1 and moves to the position of the transfer electrode 5, the charge of the transfer paper 4 charged by corona discharge of the transfer electrode 5 causes the transfer paper 4 to function as a resistance. There is a problem that toner is discharged through the transfer paper guide plate 7 and a toner dropout occurs in the toner transfer under high humidity. Regarding this problem, it is considered that the transfer paper guide plate 7 is insulated and supported from the main body frame.
The transfer field becomes too strong, resulting in "repellent" development. In addition, lightning may be easily struck on a metal part in the vicinity, which may cause a malfunction.

-Means for Solving the Problems-In order to solve the above-mentioned problems, the present invention includes a transfer paper guide plate having a spacer at the tip which contacts the peripheral surface of the photoconductor drum, and the transfer paper guide plate is provided by a pressing spring. In an electrophotographic copying machine in which the front end of the plate is pressed against the peripheral surface of the photoconductor drum with a gap, the transfer paper guide plate and the pressing spring are supported by an apparatus frame with an insulator, and the transfer paper guide plate and the pressing spring are resisted. The present invention provides an electrophotographic copying apparatus installed on the apparatus frame via a container.

-Embodiment- FIG. 1 is a configuration diagram of a main part showing an embodiment of the present invention. The photosensitive drum 1, which is rotationally driven in the direction of arrow P, is provided with a developing device 10, a paper feeding device 11, a transfer electrode 5, a separation electrode 6 and the like in order along the peripheral surface thereof. Of these, the paper feeding device 1
Reference numeral 1 denotes a transfer paper 4 whose front end is an insulating paper feed roller 3 and a guide 3.
When the sheet is ready to be fed at the position A and the toner developing surface of the photosensitive drum 1 is located at the tip of the transfer sheet guide plate 7, timing control is performed so that the tip of the transfer sheet 4 comes to the position.

The transfer paper guide plate 7 in the paper feeding device 11 is made of metal, and its rear end portion is cantilevered by a rotating shaft 13 by an electrically insulating supporting member 12, and the photosensitive member with the rotating shaft 13 as a fulcrum. It is made rotatable to the side of the body drum 1. Further, a pair of spacers 7A is provided at the front end of the transfer paper guide plate 7 at both ends which become the non-image portion of the photosensitive drum 1, and a gap between the front end of the transfer paper guide plate 7 and the peripheral surface of the photosensitive drum 1 is set. To be done.

On the transfer paper guide plate 7, sub guide plates 7B for suppressing the curling of the transfer paper 4 to the upper side are provided at both side ends thereof.
Is stopped by.

On the lower surface of the transfer paper guide plate 7, a pressing spring 9 bent between the transfer paper guide plate 7 and the supporting member 12 is provided. It is biased to the 1st side. Here, one end of the pressing spring 9 is grounded to the device frame 15 via the resistor 14.

In the operation of the present embodiment having the above-described paper feeding device configuration, the transfer paper 4 is fed toward the surface of the photosensitive drum 1 and is used for the transfer of the toner image by the transfer electrode 5, which is the same as the conventional one.

Here, the transfer paper guide plate 7, the sub guide plate 7B, and the pressing spring 9 are supported by an insulating support member 12 and are grounded via a resistor 14. With this configuration, a stable transfer operation can be obtained regardless of the moisture absorption of the transfer paper 4. That is, even if the moisture absorption state of the transfer paper 4 is high or low, the charged electric charge due to the corona discharge from the transfer electrode 5 flows to the ground side through the resistor 14, and this flow is due to the resistance value of the resistor 14 and the transfer paper. It is almost decided by the resistance value of 4. Therefore, if the resistance value of the resistor 14 is appropriately set to a high resistance, a proper image can be obtained even when the transfer paper 4 is in a high humidity and low humidity while suppressing the flow of the charge to the ground side. It does not induce "repellent" development or malfunction.

In the embodiment, the case where the ground resistance is determined by one resistor 14 is shown. This is a structure in which the resistance value is switched between the summer when the humidity of the transfer paper is high and the winter when the humidity is low as a plurality of resistors. Become effective.

-Effects of the Invention-As is apparent from the above description, the present invention has a configuration in which an electrophotographic copying apparatus including a pressing transfer paper guide plate is configured to ground the transfer paper guide plate and its pressing spring via a resistor. Therefore, the charge of the transfer paper given by corona discharge from the transfer electrode is maintained at an appropriate potential, and the high humidity of the transfer paper,
There is an effect that proper transfer can be performed regardless of low humidity. And
According to the present invention, since the transfer paper guide plate and its pressing spring are grounded via the resistor, the number of parts and the number of parts are smaller than those in the case where the transfer paper guide plate and the pressing spring are individually grounded using resistors. It is possible to obtain an electrophotographic copying machine with reduced manufacturing cost.

[Brief description of drawings]

FIG. 1 is an apparatus configuration diagram showing an embodiment of the present invention, and FIGS. 2 (A) and 2 (B) are schematic views of a conventional sheet feeding apparatus. 1 ... Photosensitive drum, 3 ... Paper feed roller, 4 ... Transfer paper, 5 ... Transfer electrode, 7 ... Transfer paper guide plate, 7A ... Spacer, 10 ... Developing device, 11 ... Paper feed Device, 12 ... Supporting member, 13 ... Rotating shaft, 14 ... Resistor, 15 ... Device frame.

Claims (1)

[Claims] 1. An electronic device comprising a transfer paper guide plate having a spacer at the tip thereof, which comes into contact with the peripheral surface of the photoconductor drum, and the front end portion of the transfer paper guide plate being pressed by the pressing spring to the peripheral surface of the photoconductor drum at intervals. In the photocopying apparatus, the transfer paper guide plate and the pressing spring are supported on the device frame by an insulator, and the transfer paper guide plate and the pressing spring are installed on the device frame via a resistor. Copying device.