JPH0566630A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent generation of wrinkling or curling and waving of a recording paper by having a front and back side of the recording paper carried in a straight line by a carrying device by a first and a second transferring device and fixing with a fixing device afterward. CONSTITUTION:The recording paper 9 on which transferring was carried out from an image carrier 2 by the first transfer device 10 is carried to a transfer position of the second transfer device 15 by the carrying device 12 and transferring is carried out. Furthermore, the recording paper 9 is carried by the carrying device 12 so that the side transferred by the first transferring device 10 and the side to be transferred by the second transferring device 15 have the front and back sides reversed. Then, after transferring is carried out on the front and back sides, the recording paper 9 is fixed by a fixing device 20. Thus, since the first transfer device 10 and the second transfer device 15 are placed separated from each other, the recording paper 9 can be carried in a straight line without being curved by the carrying device 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine or a printer, and more particularly to an image forming apparatus capable of forming images on both sides.

[0002]

2. Description of the Related Art Conventionally, in a copying machine, a toner image on a photoconductor is formed by transferring and fixing it on the surface of a recording paper, and then inverted to transfer the toner image on the photoconductor to the back surface of the recording paper.
It is known to become established.

When two sheets of recording paper, such as an envelope, are used as a recording paper, curls occur when transfer and fixing are performed on the front surface, and jams easily occur when transferring and fixing the back surface. There is a problem in that unevenness in density occurs due to unevenness or waviness.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus which solves the above-mentioned conventional problems and is capable of smoothly forming a high quality image on the front and back surfaces of an envelope. I am trying.

[0005]

An object of the present invention is to provide an image forming apparatus for transferring and fixing a toner image formed on an image bearing member to a recording sheet fed from a sheet feeding device,
A first transfer device and a second transfer device are provided separately from each other in the moving direction of the image carrier, and a transport device is provided to transport the recording paper after the transfer by the first transfer device to the transfer position by the second transfer device. In the conveying device, the surface of the recording paper in contact with the latent image carrier is the first transfer position by the first transfer device and the second transfer position by the second transfer device.
This is solved by the image forming apparatus, which is formed so as to be reversed at the second transfer position by the transfer device, and the recording sheet after transfer at the second transfer position is sent to the fixing position.

[0006]

According to the present invention, the recording paper transferred from the image carrier by the first transfer device is transferred to the transfer position by the second transfer device by the transfer device and transferred. The transport device transports the recording paper such that the transfer surface of the first transfer device and the transfer surface of the second transfer device are turned upside down. After the front and back are transferred, the recording paper is fixed by a fixing device.

Since the first transfer device and the second transfer device are arranged apart from each other, the transfer device can transfer the recording paper in a straight line without curving, and thus curling, wrinkling, waviness and the like are not generated. To prevent jams and uneven density.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described based on the embodiments shown in the drawings.

In FIG. 1, an image bearing member 2, for example, a photosensitive belt is provided on a main body 1 of a printer as an example of an image forming apparatus, and the photosensitive belt 2 is charged by a charging charger 3 while moving, and LED light is emitted. Image light is emitted by the system 4 to form an electrostatic latent image. The latent image on the photosensitive belt 2 is developed by the developing device 5 to form a toner image.

The toner image on the photosensitive belt 2 is first transferred from a paper feeding device 6, for example, a paper feeding cassette by a paper feeding roller 7 to a recording paper 9 which is timely fed by a registration roller 8 on the upper surface in the figure. The transfer is performed at the first transfer position under the action of the first transfer device 10.

The recording paper 9 after transfer is electrostatically separated from the photosensitive belt 2 under the action of the separation charger 11, and is conveyed by the conveying device 12, for example, a conveying belt.

After the transfer, the photosensitive belt 2 is destaticized by the destaticizing lamp 13 and the cleaning device 14, the residual toner is removed, and the steps from charging are repeated. The removed toner is collected by the cleaning device 14.

Apart from the first transfer device 10, the second transfer device 1 is separated from the first transfer device 10 in the moving direction of the photosensitive belt 2.
5, the toner image formed on the photosensitive belt 2 in the image forming process after the transfer by the first transfer device 10 is transferred by the second transfer device 15 to the back surface of the recording paper.

The carrying device 12 for carrying the recording paper after the transfer by the first transfer device 10 is formed so as to be movable between a first position shown by a solid line and a second position shown by a broken line in FIG. At the first position, the recording paper after being transferred by the first transfer device is received, and at the second position, the recording paper can be conveyed to the transfer position by the second transfer device 15.

The conveying device 12 is most simply formed as a conveying belt device having a belt 18 wound around a first belt wheel 16 and a second belt wheel 17, for example, around the axis of the first belt wheel 16. First, the second belt wheel 17 is turned as shown by the arrow B, and is switchable between the first position shown by the solid line and the second position shown by the broken line.

At the first position, the belt 18 of the transport device 12 transports the recording paper transferred by the first transfer device 10 in the direction of the receiving arrow. At the transfer position of the first transfer device 10, the photosensitive belt 2 faces the recording paper above the conveying path of the recording paper 9.

At the second position, the belt 8 of the transport device 12 is fed backward, and the recording paper 9 is transported to the transfer position by the second transfer device 15 as shown by the arrow. At the transfer position by the second transfer device 15, the photoconductor belt 2 is arranged so as to face the recording paper 9 below the conveyance path of the recording paper 9.

In the first transfer device 10 and the second transfer device 15, the photosensitive belt 2 and the transfer device are vertically or horizontally reversed with respect to the conveyance path of the recording paper 9. Therefore, the transport device 12 transports the recording paper 9 as it is without inverting the front and back sides, and thus the same effect as when the front and back sides are reversed is obtained.

The recording paper after the transfer by the first transfer device 10 is conveyed by the conveyor belt 18 at the first position, the conveyor belt 18 is switched to the second position at a predetermined position, and the recording paper is secondarily transferred by being reversely driven. It is sent to the transfer position by the device 15.

Since the recording paper after being transferred by the second transfer device 15 has been transferred on both the front and back sides, it is separated from the photosensitive belt 2 by the separating device 19, is sent to the fixing device 20, and is fixed and then the post-ejection portion. It is discharged to 30.

When an image is formed on the back surface of the recording paper 9, a toner image is newly formed on the photosensitive belt 2 separately from the front surface.

Since the chargers of the first transfer device 10 and the second transfer device 15 have different current setting positions for the front surface and the back surface of the recording paper, they are set separately.

As shown in FIG. 2, the conveying device 12 has a plurality of thin belts 18 wound around a first belt wheel 16 and a second belt wheel 17 and arranged at intervals.
The shaft is driven by a driving device (not shown) via the belt 21.

A fan-shaped gear 23 is fixed to a carrier frame 22 supporting the first belt wheel 16 and the second belt wheel 17 concentrically with the axis of the first belt wheel 16, and the fan-shaped gear 23 is the first gear 24. , The second motor 25, and the third gear 26 are used to make a reciprocating swing movement to a predetermined angle by a drive motor 27.

A suction fan 28 is arranged on the transport frame 22, and air is sucked through an opening 29 of the transport frame 22 formed between the belts 18 so that the belt 18 is sucked.
The recording paper conveyed by is sucked toward the belt 18 so that the recording paper is conveyed in close contact with the belt 18.

The control device is constructed as shown in FIG. 3, and the control unit 40 performs ON / OFF control and timing control of each high voltage power source 41 such as a charging charger, a developing bias, a transfer charger, a separation charger, etc. Proper output is produced.

Although an example of a photosensitive belt is shown as the image bearing member, it is naturally applicable to the case where a photosensitive drum is used.

[0028]

According to the present invention, even on double-sided recording paper such as envelopes, it is possible to transfer both front and back surfaces before fixing,
It has become possible to prevent jams and wrinkles and obtain high quality images.

[Brief description of drawings]

FIG. 1 is an overall schematic diagram of an image forming apparatus according to the present invention.

FIG. 2 is a perspective view of a transfer device.

FIG. 3 is a schematic diagram of a control device.

[Explanation of symbols]

 2 image carrier 10 first transfer device 12 transport device 19 second transfer device 20 fixing device

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location G03G 15/00 108 7369-2H 15/16 7818-2H

Claims (3)

[Claims] 1. An image forming apparatus for transferring and fixing a toner image formed on an image carrier onto recording paper fed from a paper feeding device, wherein the first transfer device and the first transfer device are separated from each other in the moving direction of the image carrier. 2 transfer device is provided, and a transport device is provided for transporting the recording paper after the transfer by the first transfer device to the transfer position by the second transfer device, and the transport device is for transferring the recording paper in contact with the latent image carrier. The surface is formed so as to be inverted between the first transfer position by the first transfer device and the second transfer position by the second transfer device, and the recording paper after transfer at the second transfer position is sent to the fixing position. An image forming apparatus characterized by. 2. The transport device is formed so as to be switchable between a first position and a second position, receives the recording paper from the first transfer position at the first position, and reversely feeds it at the second position. The recording paper is formed so as to be able to be conveyed at the two transfer positions, and the image carrier faces the upper surface of the conveyance path at the first position and the lower surface of the conveyance path at the second transfer position. The image forming apparatus according to claim 1. 3. The conveying device is formed as a conveying belt that conveys the recording paper in a substantially linear shape, and is formed so as to be capable of swivel switching movement around a fixed central axis between a first position and a second position. The image forming apparatus according to claim 2, wherein the image forming apparatus is an image forming apparatus.