JPH02213879A - Paper peeling device in electrophotographic device - Google Patents

Abstract

PURPOSE:To prevent defective peeling of paper by providing a paper peeling device with a grounded peeling plate, which is composed of a conductive body, arranged along the axial direction of a transfer roller on the paper ejecting side in a transfer part but on the transfer roller side rather than the ejected paper side. CONSTITUTION:The peeling plate 32 as the paper peeling device is arranged below an intermediate transfer belt device but at the rear of the second transfer part 20e. The peeling plate 32 is a plate-like member erected along the axial direction of the second transfer roller 22. Since the upper forward end of the peeling plate 32 bends forward, the forward end comes close to the second transfer part 20e although the plate is erected at the rear of the second transfer roller 22. Therefore, a paper 23 is carried straight as it is without moving upward together with an intermediate transfer belt 20d. Thus, the paper 23 ejected from the second transfer part 20e is securely peeled from the intermediate transfer belt 20d.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is an electrophotographic device that uses a transfer roller system in a transfer unit that transfers a toner image onto a sheet of paper. The present invention relates to a paper peeling device for separating paper from a medium.

[Conventional technology]

In addition to using a corona transfer method using a transfer charger in a transfer section, an electrophotographic apparatus may also employ a transfer roller method. This transfer roller method transfers the toner image formed on the photoreceptor or intermediate transfer medium onto the paper by pressing a rotating transfer roller to which an electric charge is applied to the photoreceptor or intermediate transfer medium through the paper. This is how it was done.

The overall structure of a full-color copying machine employing the above transfer roller method will be explained based on FIG. 3.

A document table 13 on which a document 12 is placed is provided on the upper surface of the device frame 11 . A photoreceptor belt device 15 is arranged below the document table 13 within the apparatus frame 11 via an optical system section 14 . The optical system unit 14 scans the original 12 with light from a copy lamp 14 a and guides reflected light from the original 12 to an exposure unit of a photoreceptor holding device 15 . Note that the lens 14b of the optical system section 14 is provided with three types of color filters consisting of blue, green, and red, and since the original 12 is scanned three times while replacing these filters, the photoreceptor belt device 15
Then, exposure using the transmitted light is performed for each filter in turn.

The photoreceptor belt device 15 is configured such that an endless photoreceptor belt 15c is passed between a driving roller L5a and a driven roller 15b, and the photoreceptor belt 15c is circulated and transported. The photoreceptor belt 15C has an organic photoreceptor (OPC) film formed on the outer surface of the belt. Further, around the photoreceptor belt device 15, a main charger 16, a developing device 17, a cleaner 18, and a static elimination lamp 19 are arranged in this order along the direction of transfer of the photoreceptor belt 15c, forming an electrophotographic device. are doing. Therefore, an electrostatic latent image is formed by exposing the outer surface of the photoreceptor belt 15c charged by the main charger 16 to the reflected light from the original 12 guided through the optical system section 14, and this electrostatic latent image is formed. A toner image is formed by the developing device 17 developing the electrolatent image. Note that the developing device 17 has developer tanks loaded with toner of three colors, yellow, magenta, and cyan, and performs development by switching the developer tank used for each of the three scans of the document 12. It looks like this. Therefore, toner images of yellow, magenta, and cyan toners are sequentially formed on the photoreceptor belt 15c that is being circulated. This yellow magenta
Each color of cyan has a complementary color relationship with blue, green, and red in the filter of the lens 14b, respectively.

Photoreceptor belt 15c in the photoreceptor belt device 15
The portion where the toner image is wound around the driven roller 15b forms a first transfer portion 15d for transferring the toner image formed by the developing device 17 to the intermediate transfer heald device 20 side. The intermediate transfer heald device 20 includes a driving roller 20a and a driven roller 20.
An endless intermediate transfer heald 20d is hung in a triangular shape between the back-up roller 20c and the intermediate transfer belt 20c.
d is transferred in a circular manner. The outer surface of the intermediate transfer roller 20d located between the drive roller 20a and the driven roller 20b is the first transfer portion 15.
The photoreceptor bell (d) is pressed against the photoreceptor bell) 15c. Further, a first transfer roller 21 to which a charge is applied is provided on the inner surface of the intermediate transfer bell l-20d that is pressed against the first transfer portion 15d. Therefore, the toner image formed on the photoreceptor bell 15c in the photoreceptor belt device 15 is attracted by the charge of the first transfer roller 21 and transferred onto the intermediate transfer bell 2Od. The yellow, magenta, and cyan toner images formed on the photoreceptor bell) 15c are transferred to the intermediate transfer bell) 2O.
A full-color toner image is created by sequentially overlapping and transferring the toner images on d.

Intermediate transfer belt 2 in this intermediate transfer belt device 20
The portion where 0d is wound around the backup roller 20c forms a second transfer portion 20e for transferring the transferred toner image onto the paper 23.

Furthermore, a second transfer roller 22 to which an electric charge is applied is arranged below the second transfer portion 20e. The second transfer roller 22 is provided to be movable up and down, and the paper 23 is transferred to the second transfer roller 22.
When passing through the transfer section 20e, the paper 23 is moved upward and brought into pressure contact with the outer surface of the intermediate transfer belt 20d.

Therefore, the full-color toner image transferred onto the intermediate transfer belt 20d is attracted by the charge of the second transfer roller 22, and is transferred onto the paper 23 passing through the second transfer section 20e. The outer surface of the intermediate transfer belt 20d, which has completed the transfer in this manner, is cleaned by the cleaner 24 to make it possible to transfer a new toner image. Further, a grounded back electrode and a roller 28 are brought into contact with the inner surface of the intermediate transfer belt 20d slightly closer to the driven roller 2ob than the second transfer portion 20e, and a closed circuit of electrical charges is formed in the intermediate transfer belt device 20. It has become so.

A paper feeding section 25 arranged below the photoreceptor belt device 15 supplies the paper 23 to the second transfer section 20e of the intermediate transfer belt device 20. Here, two paper feed cassettes 26, 26 can be attached to the device frame 11, and the paper 23 is supplied from either one of these paper feed cassettes 26, 26 by the paper feed section 25. . Further, the paper 23 that has passed through the second transfer section 20e is fixed with a toner image by a fixing device 27 disposed further to the side of the intermediate transfer belt device 20, and further fixed on the device frame body 23.
1 It is designed to be discharged outside.

The transfer roller method uses the second transfer roller 22 in the second transfer section 20e that transfers the toner image onto the paper 23 as described above.

The toner image transfer action in the second transfer section 20e will be explained based on FIG. 4.

The backup roller 20c has a roller portion made of insulating rubber such as silicone rubber. This hack-up roller 20c rotates as the intermediate transfer heald 20d circulates. The second transfer roller 22 is made of a conductive metal such as stainless steel. The second transfer roller 22b is driven by a drive device of the paper conveyance system, and rotates in the opposite direction to the hack-up roller 20c. Further, this second transfer roller 22 is
A charge is applied by a power source 29.

Here, assuming that the toner image on the intermediate transfer belt 20d is positively charged, the second transfer roller 22 is negatively charged as shown.

When the paper 23 passes through the second transfer section 20e, it is pressed against the outer surface of the intermediate transfer heald 20d by the second transfer roller 22. Then, the positively charged l.toner image on the intermediate transfer belt 20d is attracted to the negative charge of the second transfer roller 22 and is transferred onto the paper 23.

[Problem to be solved by the invention]

However, the intermediate transfer heald 20d that transports the positively charged toner image to the second transfer portion 20e also has a tendency to be positively charged. Moreover, the paper 23 pressed by the negatively charged second transfer roller 22 is negatively charged when passing through the second transfer section 20e. For this reason, the paper 23 that has passed through the second transfer section 20e is attracted toward the intermediate transfer belt 2Od whose leading edge 23a has a positive charging tendency as shown by the arrow A, so that the paper 23 from the intermediate transfer belt 20d is There is a risk of peeling failure. Note that this also applies even if the polarity of the charged charges is reversed.

Furthermore, such peeling defects are not limited to the above-mentioned full-color copying machines, but also occur in electrophotographic devices that have a transfer roller-type transfer unit that transfers toner images from an intermediate transfer medium or photoreceptor to paper using a transfer roller. It is a common trick.

In addition, in the corona transfer method that uses a transfer charger instead of a transfer roller, in order to peel off the paper after transfer,
AC charge removal is performed using a peeling charger, and the paper is forcibly peeled off from the intermediate transfer medium or photoreceptor using a peeling claw.

However, when a peeling charger is used in the transfer roller method, the charging of the transfer roller is affected by the AC charge removal, causing problems such as the toner image transferred to the paper becoming striped. In addition, in the method using a peeling nail, the tip of the peeling nail comes into sliding contact with the intermediate transfer medium or the photoreceptor, so it is required to use a material with high hardness for the intermediate transfer medium or the photoreceptor. It cannot be used for a flexible intermediate transfer medium such as the intermediate transfer belt 20d in a machine. For this reason, it is difficult to apply the paper peeling device used in the conventional transfer section using the corona charging method to the transfer roller method.

Therefore, in an electrophotographic apparatus having a conventional transfer roller-type transfer section, there is a high possibility that the paper will fail to peel off at the transfer section, and problems such as paper jams are likely to occur.

[Means to solve the problem]

In order to solve the above-mentioned problem, a paper peeling device in an electrophotographic apparatus according to the present invention brings a sheet of paper into pressure contact with a toner image forming medium by a rotating transfer roller to which an electric charge is applied, thereby forming a toner image on the toner image forming medium. In an electrophotographic device having a transfer roller-type transfer section that transfers a toner image onto a sheet of paper, on the paper ejection side of the transfer section and on the side of the transfer roller from the ejected paper, there is an axial direction of the transfer roller. It is characterized by a peeling plate made of a plate-shaped grounded conductor arranged along the .

[For production]

The toner image forming medium forms a toner image on the circumferential surface of a drum or the surface of a belt. However, in addition to media on which a toner image is formed by direct development, such as a photoreceptor, there are also media on which a toner image formed on a photoreceptor is transferred, such as an intermediate transfer medium.

For example, if the toner image on the toner image forming medium is positively charged, a negative charge will be applied to the transfer roller. Therefore, when the paper is pressed against the toner image forming medium by the transfer roller, the positively charged toner image is attracted to the negative charge of the transfer roller and transferred onto the paper.

Further, during this transfer process, the paper is negatively charged by the transfer roller to which a negative charge is applied. For this reason, conventionally, the toner image forming medium, which has a tendency to be positively charged, is attracted to the toner image forming medium, resulting in peeling failure. However, in the present invention, the paper discharged from the transfer section approaches a peeling plate disposed on the paper discharge side of the transfer section. For this reason, a release plate made of a conductive material and grounded is
A positive charge will be induced on the side toward which the paper approaches.

The paper is then attracted to the positive charge induced in the release plate. Since this peeling plate is disposed closer to the transfer roller than the ejected paper, the direction in which the paper is sucked is the direction in which the paper is peeled off from the toner image forming medium. Note that the same applies when the polarity of the charged charges is opposite to the above.

As a result, the paper discharged from the transfer section is reliably separated from the toner image forming medium and can be moved onto the normal discharge path.

Note that the peeling plate must be placed close to the paper ejection path in order to reliably suck the paper. However, when the paper comes into contact with this release plate,
The positive charge may cause disturbance in the unfixed toner image. Therefore, if there is a risk of contact,
It is necessary to attach a shielding plate or the like made of an insulator to the separation plate made of a conductor to prevent the paper from coming into direct contact with the conductor portion.

〔Example〕

An embodiment of the present invention will be described below based on FIGS. 1 and 2.

This embodiment shows a case where the pull color copying machine shown in FIG. 3 is provided with a paper peeling device.

For convenience of explanation, components having the same functions as those of the full-color copying machine shown in FIG. 3 and the conventional example shown in FIG. 4 are given the same reference numerals.

The configuration of the intermediate transfer belt device 20 in a full-color copying machine will be explained based on FIG. 2.

The intermediate transfer belt device 20 is configured such that an endless intermediate transfer belt l-20d is hooked around a driving roller 20a, a driven roller 20b, and a backup roller 20c in a triangular shape, and the intermediate transfer belt 20d is circulated and transported. be.

The drive roller 20a is rotated in the direction of the arrow by a copying process drive device (not shown). The driven roller 20b is disposed below and in front of the drive roller 20a, and rotates as the intermediate transfer belt 20d circulates. The backup roller 20c is disposed below the drive roller 20a and behind the driven roller 20b, and is arranged below the drive roller 20a and behind the driven roller 20b.
It rotates according to the circular transfer of d. In addition, these driven rollers 20b and backup rollers 20
c is arranged so that the plane connecting the lower ends of each circumferential surface is substantially horizontal.

Note that a grounded back electrode roller 28 is provided slightly forward of the backup roller 20c in the intermediate transfer belt device 20.

This back electrode roller 28 forms a closed circuit for electrical charges in the intermediate transfer belt device 20 by coming into contact with the inner surface of the intermediate transfer belt 20d.

The toner image formed on the photoreceptor drum 15c explained in FIG. become. This toner image is transferred to the intermediate transfer heald 20d in the following order: the driven roller 20b, the backup roller 20c, and the drive roller 20a.
It is transferred in a circular manner. And photoconductor bell) 15c
When the toner image of the first color is transferred, the toner image of the next color is superimposed and transferred after one rotation of the intermediate transfer heald 20d, and the toner image of the last color is superimposed and transferred after one more rotation. Full-color toner images using the three primary colors of yellow, magenta, and cyan are transferred to the intermediate transfer belt l-20d.
It is supposed to be formed on top.

Intermediate transfer heald 2 in the intermediate transfer heald device 20
A portion where 0d is wound around the pack unroller 20c forms a second transfer portion 20e.

This second transfer portion 20e is a position for transferring the full-color toner image formed on the intermediate transfer heald 20d onto the paper 23.

A second transfer roller 22 is provided below the second transfer portion 20e.
is located. The second transfer roller 22 is made of a conductive metal such as stainless steel, and is charged with a power supply 29 . The roller portion of the backup roller 20c is made of insulating rubber such as silicone rubber. The second transfer roller 22 is driven by a paper conveyance system drive device (not shown) to rotate in the opposite direction to the bank up roller 20c. Further, the second transfer roller 22 is installed to be movable up and down, and is configured to move upward and downward based on instructions from a control device (not shown). That is, the second
When the transfer roller 22 is lowered, a gap is created between it and the intermediate transfer belt 20d, and when the second transfer roller 22 is raised, the outer surface of the intermediate transfer belt 20d is pressed at the second transfer portion 20e. It is supposed to be done.

A paper conveying roller 30 and a paper guide 31 are provided below the intermediate transfer holding device 20 and on the front side of the second transfer section 20e. The paper 23 from the paper feed section 25 explained in FIG.
0 and the paper guide 31 to the second transfer section 20e.

A peeling plate 32 serving as a paper peeling device is arranged below the intermediate transfer belt device 20 and on the rear side of the second transfer section 20e. This peeling plate 32 is a plate-like member that stands upright along the axial direction of the second transfer roller 22 . The upper tip of the peeling plate 32 is bent forward, so that the tip of the peeling plate 32 approaches the second transfer portion 20e even though it is erected behind the second transfer roller 22. It has become.

The configuration of the peeling plate 32 will be explained in more detail based on FIG. 1.

The peeling plate 32 is composed of an SO3 plate 32a, an AI plate 32b, and a PET plate 32c. SUS plate 3
2a is made of a stainless steel plate having a width comparable to that of the second transfer roller 22, and is similar to the device frame 1 explained in FIG. 3 above.
1, and is erected parallel to the second transfer roller 22 near and behind it. Also, this SUS plate 32
The upper tip part of a is bent forward at an angle of about 40 to 60 degrees. Furthermore, this SUS plate 32a is
As shown, the base side is grounded. The AI board 32b has a plate shape having the same width as the SUS board 32a, and is made by bonding a polyethylene terephthalate plate, which is an insulator, to one surface of an aluminum plate, which is a conductor. This AI plate 32b has the other side surface of the aluminum plate fixed to the front side surface of the bent end portion of the SUS plate 32a, and is electrically connected. Further, the tip of this AI plate 32b is designed to protrude diagonally upwards than the tip of the SUS plate 32a. However, the tip of this AI plate 32b is located slightly below the conveyance path of the paper 23 discharged from the second transfer section 20e. The PET board 32c is made of a polyethylene terephthalate board having the same width as the Al board 32b, and is fixed to the polyethylene terephthalate board that is the front surface of the AI board 32b. This PET board 32c has a tip that protrudes slightly diagonally above the tip of the AI board 32b. Moreover, the lower end side of this PET board 32c is bent vertically and protrudes downward parallel to the lower part of the SUS board 32a.

The transfer action of the second transfer section 20e provided with a paper peeling device using the peeling plate 32 will be described.

The second transfer roller 22 is located below except when the paper 23 passes through the second transfer section 20e. When the paper 23 is transported near the second transfer section 20e by the paper transport roller 30 and the paper guide 31, the second transfer roller 22
rises, and its circumferential surface contacts the outer surface of the intermediate transfer belt 20d at the second transfer portion 20e. Then, the leading edge 23a of the paper 23 that has immediately reached the second transfer portion 20e is caught between the second transfer roller 22 and the intermediate transfer belt 20d. At this time, the paper 23 is transferred to the intermediate transfer heald 2.
It is designed to be conveyed in synchronization with the movement of the full-color toner image formed on Od.

The paper 23 that has reached the second transfer section 20e in this way is
While being pressed against the intermediate transfer belt l-20d by the second transfer roller 22, it is conveyed at the same transport speed as the intermediate transfer belt 20d. Here, assuming that the full-color toner image on the intermediate transfer belt 2Od is positively charged, the second transfer roller 22 is negatively charged by the power source 29 as shown. Then, the toner images on the intermediate transfer belt 20d are attracted by the negative charge of the second transfer roller 22 and are sequentially transferred onto the paper 23 passing through the second transfer section 20e.

The leading end 23a of the paper 23 discharged from the second transfer section 20e approaches the leading end of the peeling plate 32 to receive the toner image. At this time, the paper 23 is negatively charged by the pressure of the second transfer roller 22 to which a negative charge is applied. Note that the intermediate transfer bell (20d) transferred from the second transfer section 20e to the drive roller 2C1a side has a tendency to be positively charged. For this reason, conventionally, paper 2
3 is attracted by the positive charge of the intermediate transfer belt 20d, and moves to the drive roller 20a side together with the intermediate transfer belt 20d, which may cause a peeling failure.

However, in this embodiment, when the paper 23 that has passed through the second transfer section 20e approaches the peeling plate 32, positive charges are induced in the AI plate 32b of the peeling plate 32.

Here, the back surface potential of the paper 23 is 1000 to 4000 V.
In the case of a relatively low potential, this paper 23 is A1
It is attracted by the positive charge induced in the plate 32b.

However, if the back surface potential of the paper 23 is 4000 to 6000 V
In the case of a high potential, A
A discharge occurs on the I plate 3.2b. However, after that, the negative charge remaining on the paper 23 causes the AI board to
It will be attracted by the positive charge induced in 2b.

Therefore, the paper 23 is conveyed straight without moving upward together with the intermediate transfer bell 20d. As a result, the paper 23 discharged from the second transfer section 20e is reliably separated from the intermediate transfer belt 20d and can be transported on the normal transport path.

Note that the negatively charged paper 23 is connected to the AI in which a positive charge is induced.
If the toner is further attracted and comes into contact with the plate 32b, there is a risk that the unfixed toner image will be disturbed. Therefore, in this embodiment, when the paper 23 is sucked by the AI board 32b and bent downward, the tip of the PET board 32c is brought into contact with the back surface of the paper 23 first. It is designed to prevent contact with the A1 plate 32b. Further, this PET plate 32c also plays a role of shielding the conductive portion of the peeling plate 32 and the second transfer roller 22.

〔Effect of the invention〕

As described above, the paper peeling device in the electrophotographic apparatus according to the present invention presses the paper against the toner image forming medium by the rotating transfer roller to which an electric charge is applied, thereby removing the toner formed on the toner image forming medium. In an electrophotographic device having a transfer roller-type transfer section that transfers an image onto paper, a transfer section is located on the paper ejection side of the transfer section and closer to the transfer roller than the ejected paper in the axial direction of this transfer roller. It has a configuration in which a peeling plate made of a plate-shaped grounded conductor is arranged along the ridge.

As a result, the paper ejected from the transfer section is reliably separated from the toner image forming medium by being attracted by the electric charge induced in the separation plate, and can be moved onto the normal ejection path.

Therefore, the present invention is effective in preventing paper peeling defects in an electrophotographic apparatus having a transfer roller type transfer section.

[Brief explanation of the drawing]

FIGS. 1 and 2 show one embodiment of the present invention, in which the first is a partially enlarged front view of a transfer section including a paper peeling device, and the second is a front view of an intermediate transfer device. . FIG. 3 is a schematic front view for explaining the overall structure of the full-color copying machine. FIG. 4 shows a conventional example, and is a partially enlarged front view of the transfer section. 20d is an intermediate transfer belt (toner image forming medium), 20e
22 is a second transfer roller (transfer roller), 23 is paper, and 32 is a peeling plate.

Claims (1)

[Claims] 1. A transfer roller method in which a rotating transfer roller to which an electric charge is applied presses the paper against the toner image forming medium, thereby transferring the toner image formed on the toner image forming medium to the paper. In an electrophotographic apparatus having a transfer section, a grounded conductive plate arranged along the axial direction of the transfer roller on the paper ejection side of the transfer section and closer to the transfer roller than the ejected paper. 1. A paper peeling device for an electrophotographic apparatus, characterized in that a peeling plate made of a body is provided.