JPH11311907A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily separate recording paper from an intermediate transfer belt. SOLUTION: In this image forming device, a toner image visualized and developed from an electrostatic latent image is carried by an intermediate transfer belt 26 and the toner image is transferred to recording paper 35. In this case, the device is equipped with an insulated slide member 32 which extends and slides the intermediate transfer belt 35 in which the toner image is transferred, a transfer roller 38 which is arranged oppositely to the slide member 32 to hold the recording paper in cooperation with the slide member 32 and to which a bias potential is applied for transferring the toner image to the recording paper 35 and a conductive electric field removal member 33 which is brought into contact with the intermediate transfer belt 26 in the downstream side than the slide member 32 and to which a reverse-bias potential is applied to remove an electrostatic electric field on the intermediate transfer belt 26.

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 in which a toner image developed from an electrostatic latent image is conveyed by an intermediate transfer belt.

[0002]

2. Description of the Related Art FIG.
FIG. 1 is a configuration diagram illustrating a conventional image forming apparatus described in Japanese Unexamined Patent Application Publication No. H10-115,004. In FIG. 5, the photosensitive drum 2 whose surface is charged by the charger 1 is driven in the direction of arrow 2a. The photosensitive layer of the photosensitive drum 2 is scanned with a laser beam 3
a) to form an electrostatic latent image on the photosensitive drum 2. Then, four color toners of yellow (Y), magenta (M), cyan (C) and black (BK) are sequentially adhered to the photosensitive layer of the photosensitive drum 2 by the developing device 4, and the photosensitive drum 2 is subjected to reversal development. To form a toner image for each color.

On the other hand, a bias potential is applied between the photosensitive drum 2 and the transfer roller 5 from a bias power supply 6, and the tension is applied to the intermediate transfer belt 8 by the spread roller 7 so as to move the arrow 8.
It is driven by the driving roller 9 in the direction of a. Then, the toner images adhered to the photosensitive drum 2 are sequentially transferred onto the intermediate transfer belt 8 for each color in a superimposed manner, and four color toner images are formed on the intermediate transfer belt 8. The toner remaining on the photosensitive drum 2 after being transferred to the intermediate transfer belt 8 is cleaned by a cleaner 10 for each color.

[0004] Subsequently, the intermediate transfer belt 8 is pressed against the recording paper 14 by the transfer roller 12 and the opposing roller 13 to which a bias potential has been applied from the bias power supply 11.
As a result, the toner images on the intermediate transfer belt 8 are collectively transferred to the recording paper 14 by the bias potential applied to the transfer roller 12. The toner remaining on the intermediate transfer belt 8 after being transferred onto the recording paper 14 is cleaned in cooperation with the opposing roller 16 by bringing the blade 15 into contact with the intermediate transfer belt 8.

[0005]

Since the conventional image forming apparatus is configured as described above, since the opposing roller 13 in which the core metal is covered with the high-resistance body is used, the image forming apparatus is opposed to the transfer roller 12. An electrostatic electric field is generated on the intermediate transfer belt 8 by a bias potential applied between the intermediate transfer belt 8 and the intermediate transfer belt 8.
There is a problem that the paper may collide with the blade 15 while being sucked and cause a jam.

In addition, since the outer dimensions of the opposing roller 13 in which the core metal is covered with the high-resistance body are increased, the distance between the intermediate transfer belt 8 and the recording paper 14 running in parallel with the opposing roller 13 is increased. Since the bias voltage is applied to the entire surface of the opposing roller 13, the intermediate transfer belt 8
The partial transfer of the upper toner starts from the upstream side of the transfer roller 12 and continues to the downstream side of the transfer roller 12. For this reason, there has been a problem that toner scattering may occur and print quality may be degraded.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide an image forming apparatus capable of easily separating a recording sheet from an intermediate transfer belt. .

It is another object of the present invention to provide an image forming apparatus which prevents toner from scattering.

[0009]

In the image forming apparatus according to the present invention, a toner image visually developed from an electrostatic latent image is carried by an intermediate transfer belt, and the toner image is transferred to a recording sheet. In an image forming apparatus, a sliding member having an insulating property for extending and sliding an intermediate transfer belt that carries a toner image, and a recording sheet arranged in opposition to the sliding member and cooperating with the sliding member. And a transfer roller to which a bias potential for transferring the toner image to the recording paper is applied, and a conductive electric field removing member that contacts the intermediate transfer belt downstream of the sliding member and applies a reverse bias potential. It is provided with.

An image forming apparatus according to the present invention is provided with a sheet detaching portion downstream of a transfer position where a toner image is transferred onto a recording sheet, for bending the intermediate transfer belt in an arc-like direction in a direction away from the recording sheet. It is.

In the image forming apparatus according to the present invention, the section of the sheet detaching section is formed in an arc shape having a radius of 5 mm to 10 mm.

In the image forming apparatus according to the present invention, a sheet separation unit is disposed downstream from the nip caused by pressing of the transfer roller.

The image forming apparatus according to the present invention has a sliding member in which a fluororesin coating layer is formed on a portion in contact with the intermediate transfer belt.

In the image forming apparatus according to the present invention, an alumina ceramic coating layer is formed on a portion of the sliding member which comes into contact with the intermediate transfer belt.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a configuration diagram showing the first embodiment, and FIG. 2 is a cross-sectional view showing a main part of FIG. In FIGS. 1 and 2, reference numeral 17 denotes a drum-shaped photosensitive member having a photosensitive layer such as a photoconductor applied on the outer peripheral surface.
It is rotatably supported in the direction of 7a. Reference numeral 18 denotes a charger for uniformly charging the photoconductor 17, and 19 denotes a laser exposure device which forms an electrostatic latent image on a photosensitive layer of the photoconductor 17 by a laser beam 19a. 20 to 23 are sequentially black (B
k), a developing device containing magenta (M), cyan (C), and yellow (Y) toners, successively depositing and developing each toner on the electrostatic latent image on the photoreceptor 17 to form a toner image Let it.

A transfer device 24 transfers the toner image on the photosensitive member 17 to an intermediate transfer belt 26 described later. Reference numeral 25 denotes a cleaner for removing toner remaining on the photoconductor 17 after transfer. Reference numeral 26 denotes a conductive intermediate transfer belt,
The toner image of each color formed on the photosensitive layer 7 is transferred to the transfer device 24.
Are sequentially superimposed and transferred. 27 is an extension roller,
A predetermined tension is applied to the intermediate transfer belt 26. 28
Is a drive roller for driving the intermediate transfer belt 26 in the direction of arrow 29. Reference numeral 30 denotes a blade, which is a recording paper 35 described later.
The toner remaining on the intermediate transfer belt 26 after the transfer to the intermediate transfer belt 26 is removed. A backup roller 31 backs up the blade 30.

Reference numeral 32 denotes a sliding member having an insulating property which is disposed to face a transfer roller 38 to be described later, and is in contact with the intermediate transfer belt 26 in a slidably extended state. Further, the sliding member 32 has a sheet detaching portion 32a having a predetermined curvature for bending the intermediate transfer belt 26 in a direction detaching from a recording sheet 35 described later on the downstream side where the intermediate transfer belt 26 is in contact. I have. Reference numeral 33 denotes a conductive electric field removing member integrated with the sliding member 32.
A reverse bias potential is applied by a bias power supply 39 described later, in contact with the intermediate transfer belt 26 downstream of 2a. The transfer pad 34 is constituted by the sliding member 32 and the electric field removing member 33. 35 is a recording paper of a predetermined size, 36 is a transport roller, and the recording paper 35 is indicated by an arrow 37.
In the direction of.

Reference numeral 38 denotes a high-resistance elastic member,
By pressing the intermediate transfer belt 26 against the sliding member 32 via the recording paper 35 with a transfer roller disposed at a position facing the toner image, the toner image on the intermediate transfer belt 26 cooperates with the sliding member 32. Is transferred to the recording paper 35. or,
The transfer roller 38 is arranged such that a deformed portion (nip portion) of the transfer roller 38 generated when the transfer roller 38 is pressed by the sliding member 32 does not cross the arc-shaped portion of the sheet separating portion 32a. 3
Reference numeral 9 denotes a bias power supply for applying a predetermined potential to the electric field removing member 33 and the transfer roller 38.

Next, the operation will be described. 1 and 2
First, the electrostatic latent image on the photoreceptor 17 is
At 23, the toner images are sequentially formed to form toner images. Next, the toner images formed on the photoreceptor 17 are successively superimposed on the intermediate transfer belt 26 and transferred to form four-color superimposed color toner images. When the toner image on the intermediate transfer belt 26 reaches the nip portion of the transfer roller 38, the toner image on the intermediate transfer belt 26 is changed by the bias potential applied between the transfer roller 38 and the electric field removing member 33. The data is collectively transferred to the recording paper 35.

When the intermediate transfer belt 26 and the recording paper 35 are conveyed to the downstream side of the transfer position where the toner image has been transferred onto the recording paper 35 in a state in which the intermediate transfer belt 26 is in close contact with the recording paper 35, the intermediate transfer belt 26 is moved by the paper releasing section 32a. Since the intermediate transfer belt 26 is bent in a direction away from the recording paper 35, the intermediate transfer belt 26 and the recording paper 35 are separated. Then, the rigidity of the recording paper 35 is conveyed in the direction of arrow 40 against the electrostatic attraction of the intermediate transfer belt 26. Thereafter, the intermediate transfer belt 26 comes into contact with the electric field removing member 33 to remove the electrostatic electric field, and then the toner remaining on the intermediate transfer belt 26 is removed by the blade 30.

As described above, since the transfer roller 38 is disposed so as to face the insulating sliding member 32, the intermediate transfer belt 26 is not affected by the bias potential outside the nip portion of the transfer roller 38. Since it is difficult to receive the toner and the toner is prevented from scattering on the intermediate transfer belt 26, the printing quality can be improved.

Further, after the toner image is transferred onto the recording paper 35, the intermediate transfer belt 26 is bent in a direction away from the recording paper 35 by the paper detaching portion 32a. In contrast, the recording paper 35 is separated from the intermediate transfer belt 26 by the rigidity of the recording paper 35, so that paper jam can be prevented.

Further, since the sheet detaching portion 32a is disposed downstream from the nip portion due to the pressing of the transfer roller 38, the intermediate transfer belt 26 of the recording sheet 35 is provided.
Can be easily separated.

Embodiment 2 FIG. FIG. 3 is a configuration diagram showing the second embodiment, and FIG. 4 is a cross-sectional view showing a main part of FIG. 3 and 4, 17 to 31, 35 to 40 are the same as those in the first embodiment. 41 is a transfer roller 38
The intermediate transfer belt 26 is in contact with the intermediate transfer belt 26 slidably extended via a coating layer 42 to be described later. Further, the sliding member 41 is located on the downstream side where the intermediate transfer belt 26 is in contact,
A paper detaching portion 41a having a predetermined curvature for bending the intermediate transfer belt 26 in a direction away from the recording paper 35 is formed.

Reference numeral 42 denotes a coating layer formed on the surface of the sliding member 41, and a fluororesin is disposed at a portion in contact with the intermediate transfer belt 26. Reference numeral 43 denotes an electric field removing member integrated with the sliding member 41, which is in contact with the intermediate transfer belt 26 on the downstream side of the sheet releasing section 41 a, and to which a reverse bias potential is applied by the bias power supply 39. The transfer pad 44 is composed of the sliding member 41, the coating layer 42, and the electric field removing member 43.

Next, the operation will be described. 3 and 4
First, the electrostatic latent image on the photoreceptor 17 is
At 23, the toner images are sequentially formed to form toner images. Next, the toner images formed on the photoreceptor 17 are successively superimposed on the intermediate transfer belt 26 and transferred to form four-color superimposed color toner images. When the toner image on the intermediate transfer belt 26 reaches the nip portion of the transfer roller 38, the toner image on the intermediate transfer belt 26 is changed by the bias potential applied between the transfer roller 38 and the electric field removing member 33. The data is collectively transferred to the recording paper 35.

When the intermediate transfer belt 26 and the recording paper 35 are conveyed to the downstream side of the transfer position where the toner image has been transferred onto the recording paper 35 in a state in which the intermediate transfer belt 26 is in close contact with the recording paper 35, the intermediate transfer belt 26 is moved by the paper releasing section 41a. Since the intermediate transfer belt 26 is bent in a direction away from the recording paper 35, the intermediate transfer belt 26 and the recording paper 35 are separated. Then, the rigidity of the recording paper 35 is conveyed in the direction of arrow 40 against the electrostatic attraction of the intermediate transfer belt 26. Thereafter, the intermediate transfer belt 26 comes into contact with the electric field removing member 33 to remove the electrostatic electric field, and then the toner remaining on the intermediate transfer belt 26 is removed by the blade 30.

As described above, since the transfer roller 38 is disposed so as to face the sliding member 41 having an insulating property, the intermediate transfer belt 26 is not affected by the bias potential outside the nip portion of the transfer roller 38. Since it is difficult to receive the toner and the toner is prevented from scattering on the intermediate transfer belt 26, the printing quality can be improved.

Further, after the toner image is transferred to the recording paper 35, the intermediate transfer belt 26 is bent in a direction away from the recording paper 35 by the paper detaching portion 41a. In contrast, the recording paper 35 is separated from the intermediate transfer belt 26 by the rigidity of the recording paper 35, so that paper jam can be prevented.

Further, since a coating layer 42 made of a fluororesin is formed on a portion of the sliding member 41 in contact with the intermediate transfer belt, the sliding member 41 and the intermediate transfer belt 26 are formed.
Of the sliding member 41 can be suppressed.

In the second embodiment, the description has been given of the case where the fluororesin coating layer 42 is formed on the portion of the sliding member 41 which comes into contact with the intermediate transfer belt 26, but the coating layer 42 is formed of alumina ceramic. Can expect the same effect.

In the first embodiment, the sheet detaching section 32a,
In the case where the paper separating portion 41a according to the second embodiment is formed in an arc shape, the recording paper 35 having a small thickness and a small rigidity can be formed by reducing the radius of the circle.
However, since the bending ratio of the intermediate transfer belt 26 increases, the durability of the intermediate transfer belt 26 decreases. Therefore, the rigidity of the recording paper 35 is weighed to 64K.
g, when the bias potential applied to the transfer roller 38 is 1,000 V, the optimum value is experimentally set to be 8 mm in the radius of the sheet separation portions 32a and 41a. However, the radius of the sheet detaching portions 32a and 41a is 5 mm to 5 mm because it differs depending on the selection of the material, thickness, and the like of the intermediate transfer belt 26.
It is desirable to set it in the range of 10 mm.

The sliding member 32 according to the first embodiment
And the electric field removing member 33 and the sliding member 41 and the electric field removing member 43 in the second embodiment have been described.
The same effect can be expected for those in which the electric field removing members 2 and 41 are separated from the electric field removing members 33 and 43.

[0034]

According to the present invention, since the transfer roller is disposed so as to face the insulating sliding member, the intermediate transfer belt is hardly affected by the bias potential.
Since the scattering of the toner on the intermediate transfer belt can be prevented, the printing quality can be improved.

According to the present invention, after the toner image is transferred onto the recording sheet, the intermediate transfer belt is bent in a direction away from the recording sheet by the sheet detaching section, so that the intermediate transfer belt resists the electrostatic attraction force of the intermediate transfer belt. Since the recording paper is separated from the intermediate transfer belt by the rigidity of the recording paper, paper jam can be prevented.

According to the present invention, by setting the radius of the cross section of the sheet detaching portion in the range of 5 mm to 10 mm, the recording sheet can be easily separated from the intermediate transfer belt and the durability of the intermediate transfer belt can be improved. Can be improved.

According to the present invention, since the sheet detaching portion is disposed downstream from the nip portion due to the pressing of the transfer roller, the recording sheet can be easily separated from the intermediate transfer belt.

According to the present invention, the frictional contact between the sliding member and the intermediate transfer belt is reduced by forming the fluororesin coating layer on the portion of the sliding member that comes into contact with the intermediate transfer belt. Can be suppressed.

According to the present invention, the friction between the sliding member and the intermediate transfer belt is reduced by forming the alumina ceramic coating on the portion of the sliding member that comes into contact with the intermediate transfer belt. Wear can be suppressed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of the present invention.

FIG. 2 is a sectional view showing a main part of FIG.

FIG. 3 is a configuration diagram showing a second embodiment of the present invention.

FIG. 4 is a sectional view showing a main part of FIG. 2;

FIG. 5 is a configuration diagram illustrating a conventional image forming apparatus.

[Explanation of symbols]

26 intermediate transfer belt, 32, 41 sliding member, 32
a, 41a paper detachment section, 33, 43 electric field removing member,
35 recording paper, 38 transfer roller, 42 coating layer.

Claims (6)

[Claims] 1. An image forming apparatus in which a toner image visually developed from an electrostatic latent image is carried by an intermediate transfer belt and the toner image is transferred to a recording sheet, wherein the intermediate transfer carries the toner image. A sliding member having an insulating property for extending and sliding the belt, and a recording member sandwiched between the sliding member and the sliding member arranged opposite to the sliding member to cooperate with the sliding member to transfer the toner image to the recording paper; A transfer roller to which a bias potential to be applied to the intermediate transfer belt is applied downstream of the sliding member, and a conductive electric field removing member which is in contact with the intermediate transfer belt and applies a reverse bias potential. Image forming apparatus. 2. A paper separating portion provided on a downstream side of a transfer position where a toner image is transferred onto a recording sheet, for bending an intermediate transfer belt in a direction away from the recording sheet. 2. The image forming apparatus according to 1. 3. The image forming apparatus according to claim 2, wherein the paper detachment section has an arc shape having a cross section having a radius of 5 mm to 10 mm. 4. The image forming apparatus according to claim 2, wherein a sheet detaching unit is disposed downstream from the nip caused by pressing of the transfer roller. 5. The image forming apparatus according to claim 1, wherein a fluororesin coating layer is formed on a portion of the sliding member that comes into contact with the intermediate transfer belt. . 6. The image forming apparatus according to claim 1, wherein an alumina ceramic coating layer is formed on a portion of the sliding member that contacts the intermediate transfer belt. .