JPH07210017A - Electrophotographic recorder - Google Patents

Abstract

PURPOSE:To prevent transfer deviation from occurring and to obtain high image quality by providing an auxiliary roller for interposing a recording paper after transfer between a photoreceptor and carrying it toward the downstream side of the recording paper carrying direction of a transfer device. CONSTITUTION:The auxiliary roller 12 is provided near the downstream side of the transfer device 6 on the downstream side of the carrying direction of the recording paper 5) so as to abut on a photoreceptive drum 1 and to be rotated altogether. By such a constitution, a toner image attached on the belt 1 is transferred on the paper 5 attracted to the belt 1 by electrostatic force and carried in accordance with the rotation of the belt 1 by the transfer device 6. Since the roller 12 on belt 1 at the back stage of the transfer device 6 is pressed to the paper 5, the paper 5 is interposed between the roller 12 and the belt 1 and prevented from being deviated with respect to the belt 1. Then, the paper 5 separated from the belt 1 is interposed between a pressure roller 7a and a fixing roller 7b and thermally fixed. Thereafter, it is ejected to the outside of a machine.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic recording apparatus having a corona discharge type transfer device and a heating roller type fixing device.

[0002]

2. Description of the Related Art As is well known, in an electrophotographic recording apparatus, after precharging a photoconductor, optical writing is performed to form an electrostatic latent image on the photoconductor, and the electrostatic latent image is formed by toner. While developing and transferring the toner image to the recording paper, the recording paper is heated and fixed and discharged to the outside of the machine.On the other hand, the toner remaining on the photoconductor is scraped off by a cleaning blade and collected as waste toner. A series of electrophotographic processes of irradiating light to remove electric charges are performed.

[0003]

By the way, in the electrophotographic recording apparatus of this type, since the recording paper is attached to the photoconductor only by electrostatic force, a part of the recording paper is nipped and conveyed by the fixing section. At this time, the recording paper may be easily displaced from the photoconductor due to uneven rotation of the fixing roller and the pressure roller. When the recording paper is displaced from the photoconductor in this way,
The toner image is dragged to cause tailing, which causes a so-called transfer deviation that looks just like a black band. Japanese Patent Laid-Open No. 5-72837 discloses a technique for preventing transfer deviation (color deviation) of each color in a color image. However, transfer deviation caused by pulling a recording paper regardless of whether it is a single color or a multicolor image. There is no mention of a technique for preventing this.

The present invention has been made in view of such a background, and an object thereof is to provide an electrophotographic recording apparatus capable of preventing transfer deviation in advance and achieving high image quality.

[0005]

In order to achieve the above object, the present invention is an electrophotographic recording apparatus having a corona discharge type transfer device and a heating roller type fixing device. It is characterized in that an auxiliary roller for nipping and carrying the recording paper after transfer between the recording paper and the photoconductor is provided on the downstream side.

In this case, the recording paper is further held between the holding means for holding the auxiliary roller so that the auxiliary roller can be brought into contact with and separated from the photoconductor, and the photoconductor during transfer to the recording paper. It is preferable to include drive control means for holding means that separates the auxiliary roller from the side of the photoconductor when the discharge of is completed, and it is desirable to further provide a scraper that contacts the auxiliary roller.

[0007]

According to the above construction, since the recording paper after transfer is conveyed while being sandwiched between the photoconductor and the auxiliary roller,
It is possible to prevent the recording sheet from being displaced from the photoconductor due to the uneven rotation of the fixing roller and the pressure roller that form the fixing device, and thereby prevent the transfer deviation.

Further, by making the auxiliary roller contactable and separable by the drive control means, the recording sheet after transfer is nipped and conveyed between the photosensitive member and the fixing roller and the heating roller during copying. After the copying, the auxiliary roller is separated from the photoconductor to prevent permanent deformation and deterioration of the photoconductor due to pressure contact of the auxiliary roller with the photoconductor.

Further, if a scraper is provided, regardless of whether or not the auxiliary roller can be contacted and separated,
It is possible to prevent toner stains on the auxiliary roller.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram of an electrophotographic recording apparatus according to an embodiment. In the figure, reference numeral 1 denotes a photoconductor belt around which a charger 2, an exposure unit 3, a developing unit 4, a corona discharge type transfer unit 6, a cleaning unit 9 including a waste toner cartridge, and a charge eliminator are arranged in the order of an image forming process. The LEDs 10 are arranged respectively. In addition, 5 is a recording sheet accommodated in a multi-stage paper feeding cassette, 7 is a heating roller type fixing device including a pressure roller 7a and a fixing roller 7b, and 11 is a micro switch (not shown) provided in a sheet discharging section. It is a paper discharge sensor consisting of (1) and a filler.

In such a configuration, a well-known electrophotographic process is executed. In the electrophotographic process, first,
After the photoconductor belt 1 is precharged by the charger 2, light is written by the exposure unit 3 to form an electrostatic latent image. The electrostatic latent image is developed by applying toner with the developing device 4. The recording paper 5 accommodated in the paper feed cassette is conveyed to the transfer portion, the toner image is transferred by the transfer device 6, and is heated and nipped by the pressure roller 7a and the fixing roller 7b to be fixed. It is discharged outside.

On the other hand, the toner remaining on the photosensitive belt 1 is scraped off by the cleaning device 9 and collected as waste toner in the waste toner cartridge.
The charge is removed by irradiating the surface of the photoconductor with light with the ED 10. The arrow a indicates the direction of conveyance of the recording paper 5. Also,
As the photoconductor, other than the photoconductor belt 1, a photoconductor drum may be used.

FIG. 2 is a perspective view of a main part according to the first embodiment. In this embodiment, an auxiliary roller 12 is provided in the vicinity of the downstream side of the transfer device 6 (downstream side in the conveying direction of the recording paper 5) so as to come into contact with the photosensitive belt 1 and rotate together.
In such a configuration, the recording paper 5 that is attracted to the photoconductor belt 1 by electrostatic force and is conveyed along with the rotation of the photoconductor belt 1 is the toner attached to the photoconductor belt 1 by the transfer device 6. The image is transferred. Here, since the auxiliary roller 12 is pressed against the photosensitive belt 1 at the subsequent stage of the transfer device 6, the recording paper 5 is sandwiched between the auxiliary roller 12 and the photosensitive belt 1, and the deviation from the photosensitive belt 1 is prevented. It
Then, the recording paper 5 separated from the photosensitive belt 1 is nipped by the pressure roller 7a and the fixing roller 7b and heated and fixed,
It is discharged outside the aircraft.

FIG. 3 is a perspective view of an essential part according to the second embodiment. In this embodiment, the scraper 1 is attached to the auxiliary roller 12.
3 is abutted. In this way, the scraper 13 can scrape off the toner on the auxiliary roller 12 that is in direct contact with the photoconductor belt 1 and prevent the backside of the recording paper 5 from being soiled.

FIG. 4 is a front view of a main portion according to the third embodiment. In this embodiment, the auxiliary roller 12 can be brought into and out of contact with the photosensitive belt 1 by the action of the solenoid 14 controlled by the control circuit 17. 15 is a solenoid 1
An arm 16 between the 4 and the auxiliary roller 12 is a biasing spring, which constitutes a drive control means of the auxiliary roller 12. In such a configuration, when the paper ejection sensor 11 shown in FIG. 1 detects the ejection of the recording paper 5 out of the machine, the control circuit 17 outputs an expansion signal to the solenoid 14. Then, the solenoid 14 operates and the arm 15
Is pressed to separate the auxiliary roller 12 from the photosensitive belt 1.

When the copy operation is started again, the control circuit 17 outputs a reduction signal to the solenoid 14. Then, the solenoid 14 operates and releases the pressure applied to the arm 15. At this time, the urging spring 16 fixed to the main body side
Is released and the auxiliary roller 12 is brought into contact with the photosensitive belt 1.

FIG. 5 is a front view of the main parts according to the fourth embodiment. This embodiment is the same as the auxiliary roller 1 in the third embodiment.
The scraper 13 which contacts 2 is added.

As with the second embodiment, the scraper 13 scrapes off the toner on the auxiliary roller 12 to prevent the backside of the recording paper 5 from being soiled.

[0019]

As is apparent from the above description, the present invention has the following effects. That is, according to the invention of claim 1, an auxiliary roller is provided on the downstream side of the transfer device in the recording paper conveyance direction so as to sandwich and convey the recording paper after transfer with the photoconductor. Since it is possible to prevent the recording sheet from being displaced from the photosensitive member due to the uneven rotation of the fixing roller and the pressure roller, it is possible to avoid the occurrence of image transfer deviation and improve the image quality.

Holding means for holding the auxiliary roller so that it can contact and separate from the photoconductor, and the recording paper is held between the photoconductor during transfer onto the recording paper, and when the recording paper is completely discharged, the auxiliary roller is held. According to the invention of claim 2, further comprising drive control means for the holding means for separating the auxiliary roller from the photoconductor side, the auxiliary roller functions only during the copy operation, and the auxiliary roller is separated from the photoconductor during the non-copy operation. Therefore, the deformation of the auxiliary roller and the deterioration of the photoconductor can be prevented.

According to the invention of claim 3, further comprising a scraper that comes into contact with the auxiliary roller, is it possible to prevent toner contamination of the auxiliary roller that is in direct contact with the photosensitive member and to have a control drive device for the auxiliary roller? Regardless of whether or not the back side of the recording paper can be removed.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of an electrophotographic recording apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view of a main part according to the first embodiment of the present invention.

FIG. 3 is a perspective view of a main part according to a second embodiment of the present invention.

FIG. 4 is a front view of a main part according to a third embodiment of the present invention.

FIG. 5 is a front view of a main part according to a fourth embodiment of the present invention.

[Explanation of symbols]

 1 photoconductor belt (photoconductor) 5 recording paper 6 transfer device 7 fixing device 12 auxiliary roller 17 scraper

Claims (3)

[Claims] 1. In an electrophotographic recording apparatus having a corona discharge type transfer device and a heating roller type fixing device, a transfer recording paper is provided between a photosensitive member and a transfer paper downstream of the transfer paper in the recording paper conveying direction. An electrophotographic recording apparatus comprising an auxiliary roller for sandwiching and conveying the sheet. 2. In an electrophotographic recording apparatus having a corona discharge type transfer device and a heating roller type fixing device, recording by the transfer device is performed because the recording paper after transfer is sandwiched between a photoconductor and conveyed. An auxiliary roller provided on the downstream side in the paper transport direction, a holding unit that holds the auxiliary roller so that the auxiliary roller can be brought into contact with and separated from the photosensitive member, and the recording paper is transferred between the photosensitive member and the photosensitive member during transfer to the recording paper. An electrophotographic recording apparatus comprising: drive control means for holding the auxiliary roller so as to separate the auxiliary roller from the photosensitive member side when the recording paper is completely discharged. 3. The electrophotographic recording apparatus according to claim 1, further comprising a scraper that comes into contact with the auxiliary roller.