JPH09101653A - Electrifying member supporting device for image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an electrifying member from being touched by hands or the like and to prevent the deterioration in electrifying function by making the projecting amount of the electrifying member from a supporting member small linked with separation of the supporting member from a photoreceptor at the time of processing jamming. SOLUTION: The supporting member 8 is provided with a rocking supporting point 81. When the jamming is caused at or in front or rear of a transfer position (nip point of image carrier 2 and transfer roller 6) and the maintenance work of the transfer roller 6 is performed, the supporting member 8 is rocked centering the rocking supporting point 81 and is moved from a normal position (a) to a release position (b), so that the transfer roller 6 and the image carrier 2 are separated. In this case, the shaft of the transfer roller 6 is supported by a part of the supporting member 8. When it descends to the release position, the projecting amount D2 of the transfer roller 6 from an end part on the side of the image carrier 2 of the supporting member 8 is smaller than the projecting amount D1 of the transfer roller 6 from the end part on the side of the image carrier 2 of the supporting member 8 at the normal position (D1>D2), so that the transfer roller 6 is hardly touched from outside.

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 using an electrostatic transfer process, such as an electrostatic copying machine and a printer.
Alternatively, the present invention relates to the transfer device, and particularly to a device that supports a charging member such as a charging roller or a transfer roller used in these devices.

[0002]

2. Description of the Related Art A toner image is formed on a running image carrier by a charged toner, and a contact type transfer charging member such as a transfer roller that runs in synchronization with the image carrier is pressed against the transfer roller to transfer the pressure contact nip portion between them. The transfer material such as paper is passed through this portion, and a transfer bias having a polarity opposite to that of the toner is applied to the transfer charging member, and the toner image on the image carrier side is transferred by the action of the electric field formed by the transfer bias. An image forming apparatus configured to transfer the image has already been presented.

As described above, the charging member of the type that comes into contact with the image carrier requires a relatively low bias voltage as compared with the type that uses a corona discharger having a wire electrode and a shield electrode. It has various advantages such as being capable of producing ozone and not generating ozone.

Further, the contact type charging member for transfer as described above can surely hold the transfer material, so that there is an advantage that the transfer deviation is less likely to occur at the transfer portion.

However, when the transfer charging member and the image carrier are separated from each other to perform maintenance or the like, when the charging member is touched by a hand or a finger, oil such as hand grease which is an insulating substance adheres to the charging member. As a result, the surface resistance of the charging member may change and the charging function may be degraded. The same problem occurs when the charging member is damaged by a nail or a ring, or when the charging member is pressed with a finger to apply a large pressure to the charging member, which causes a large distortion.

Particularly, in the case of the transfer roller as described above,
When jamming is performed by opening the image carrier and the transport unit including the transfer roller due to paper jam (jam), the transfer roller is in a state where it is easy to touch, and good transfer from the image carrier to the transfer material is possible. It is also a factor that hinders and stains the operator's hands and clothes.

In order to prevent the above-mentioned problems, in Japanese Patent Laid-Open No. 6-3977, a transfer roller cover is attached by a separate member, and the transfer roller is interlocked with the operation of separating the transfer roller from the image carrier, and when paper jam or maintenance occurs. When the transfer roller is separated from the image carrier, the cover member covers the transfer roller to prevent it from being touched by a hand or the like.

However, this method uses a separate member called a cover member, and thus has a problem that the device becomes large and complicated and the cost increases.

[0009]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and prevents foreign matters such as hands from contacting the charging member at the time of maintenance, jam processing, etc. An object of the present invention is to provide a simple and inexpensive charging member supporting device that does not deteriorate the charging function of the member and does not increase the size of the device.

[0010]

To achieve the above object, the present invention provides a charging member in an image forming apparatus having a charging member in contact with the image carrier and a supporting member for supporting the charging member. In the supporting device, the supporting member is movable between a position where the charging member is in contact with the image carrier and a position where the charging member is in contact with the image carrier, and when the charging member is in contact with the image carrier, The feature is that the amount of protrusion from the support member is large.

Further, when the charging member is separated from the image carrier, the amount by which the charging member projects from the supporting member becomes negative, that is, the charging member enters the supporting member. it can.

Further, the support member is swingable about a swing fulcrum, supports the charging member at a position apart from the swing fulcrum, and is capable of coming into contact with and separating from the charging member, and the spring. And a push-up member that can be moved toward and away from the means, the push-up member abuts the spring means to press the spring means against the charging member when the charging member is abutting the image carrier,
When the charging member is separated from the image carrier, it may be separated from the spring means to separate the spring means from the charging member.

In the above, the charging member may be a transfer roller for transferring the image of the image carrier to a recording material.

It is desirable that the support member has a guide for supporting the shaft of the transfer roller, and that the lower end of the transfer roller does not come into contact with the support member when the transfer roller separates from the image carrier. .

The supporting member may also serve as a conveying means for conveying the recording material after the transfer.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A charging member supporting device in an image forming apparatus of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a charging member supporting device of the present invention. First, the image carrier 2 is exposed to light by being irradiated with light from the static elimination lamp 1.
It is charged to the reference potential of −150 V from the state where V is not charged. Next, the image carrier 2 is contacted with the charging roller 3
Are uniformly charged (-1100V). The charging roller 3 is composed of a cored bar, a conductive layer on the outer periphery thereof, and a resistance layer on the outer periphery thereof, and a predetermined DC bias is applied from a power source (not shown). The uniformly charged image carrier 2 is exposed according to the information of the original image, and an electrostatic latent image is formed. Here, the surface potential of the portion irradiated with light is 0 to -2.
It becomes 90V.

Toner is selectively attached to the electrostatic latent image on the image carrier 2 by the developing unit 4 to visualize it (toner image). At this time, the bias applied to the developing roller 5 is −
It is around 800V.

This toner image is transferred by a transfer roller 6 as a charging member onto a transfer material (not shown) such as a copy paper conveyed to a transfer section between the image carrier 2 and the transfer roller 6. The transfer roller 6 is pressed against the image carrier 2, and a voltage having a polarity opposite to that of the toner is applied by a power source (not shown).

The transfer material on which the toner image has been transferred is conveyed to a supporting member 8 which also serves as a conveying means, is fixed by a fixing device (not shown), and is sent out of the image forming apparatus.

After the transfer, the image carrier 2 is cleaned by the cleaning device 7.
After the residual toner is removed by, the charge is removed again by the charge removing lamp 1 and is repeatedly used for image formation.

FIG. 2 is a diagram for explaining the operation of the transfer roller supporting device of the present invention. In the figure, reference numeral 81 indicates a swing fulcrum of the support member 8. When a jam occurs at or before or after the transfer position (nip point between the image carrier 2 and the transfer roller 6) or when the transfer roller 6 is maintained, the support member 8 is swung about its swinging fulcrum 81. The transfer roller 6 and the image carrier 2 are separated from each other by moving and moving from the normal position (a) to the release position (b). Here, the shaft of the transfer roller 6 is supported by a part of the support member 8. When the support member 8 is lowered to the release position as shown in FIG.
Of the transfer roller 6 protruding from the end portion of the image bearing member 2 side
Is smaller than the amount D1 of the transfer roller 6 protruding from the end of the supporting member 8 on the image carrier 2 side at the normal position as shown in FIG. 2A (D1> D2), and the transfer roller 6 is contacted from the outside. Making it difficult. The specific configuration of D1> D2 is the same as that of the embodiment of FIG. 3 described below.

FIG. 3 shows another embodiment of the supporting device for the transfer roller 6. (A) shows the state of the normal position (at the time of image formation). A shaft 61 is projected at both ends of the transfer roller 6, and the whole including the shaft 61 is accommodated in the support member 8. In FIG. 3, the support member 8 is divided into a front support member 80 and a rear support member 82, both of which are swing shafts 8.
3 The rear support member 82 is attached to the image forming apparatus main body at the swing fulcrum 81 as described above. A spring means 84 composed of a leaf spring is attached to the lower side of the front side support member 80, and at a normal position (at the time of image formation), a push-up member 85 pushes up the spring means 84 from below to move the front side support member 80. With pushing up,
The shaft 61 is pushed up to bring the transfer roller 6 into pressure contact with the image carrier 2. The push-up member 85 is connected to the main body of the image forming apparatus at a fulcrum 87 below and is rotatable around the fulcrum 87. Further, a handle 86 for manual operation is attached to the push-up member 85.

FIG. 3 (b) shows the state of the release position (during jam processing and maintenance). At the time of release, the handle 86 is moved in the direction of the arrow to rotate the push-up member 85 to the lower left in the figure. As a result, the front support member 80 pushed up in the normal position is lowered by its own weight, and the tip of the spring means 84 is also lowered, so that the shaft 61 of the transfer roll 6 is also lowered by its own weight, and the transfer roller 6 is also supported by its own weight. Lowering relative to 80, D1> D
It becomes 2.

As shown in FIG. 4, in order to improve the positional accuracy of the transfer roller 6 and the like, the front support member 80 is moved relative to the shaft 61 so that the transfer roller 6 can move vertically with respect to the front support member 80. A guide 88 is provided.
At this time, the spring means 84 includes the guide 88 and the front support member 80.
The shaft 61 is pushed up from the lower side in a gap 89 between the shaft 61 and.

FIG. 5 shows still another embodiment, (a) shows a normal position, and (b) shows a release position. FIG. 5A shows FIG.
5B is similar to FIG. 4B, but the position of the transfer roller 6 relative to the front support member 80 is relatively lower in FIG. 5B, and the end surface 9 of the front support member 80 on the image carrier side is lower.
The upper end surface 91 of the transfer roller 6 is lower than 0 (the protruding amount D2 is negative). At this time, if the transfer roller 6 lowers too much and comes into contact with the bottom surface 92 of the transfer roller installation portion of the front support member 80, the back surface of the transfer paper or the image carrier 2 may be contaminated due to the adhesion of foreign matter, etc. When the lower limit position is reached, the gap s can be secured by the guide 88 shown in FIG. 4 so as not to contact the bottom surface 92 of the support member.

FIG. 6 is a modification of FIG. 5 (b). For simplicity, the spring means 84 have been omitted from the figure. Further, in FIG. 6, the transfer roller installation portion bottom surface 92 of FIG. 5B is removed and opened, and the lower end portion 94 of the transfer roller 6 projects downward from the lower end portion 93 of the front support member 80 in the released position. There is.
This makes it possible to reduce the thickness of the front support member 80 and prevent the transfer roller 6 from contacting the bottom surface 92 of the transfer installation portion. Also in this case, the lower limit position of the transfer roller 6 is as shown in FIG.
It may be determined by the guide 88 shown in FIG.
A spacer or the like may be installed between the main body and the front support member 80 so that the lower end portion 94 of the main body does not come into contact with the main body.

As described above, the supporting member (conveying means) is moved relative to the supporting member 8 of the transfer roller 6 in association with the contact and separation of the supporting member (conveying means) from the photosensitive member at the time of jam processing, so that the transfer roller can be easily operated. Oil on the surface, scratches,
It is possible to prevent pressure distortion and ensure good transferability. Further, in the above embodiment, the charging member supporting device can be manufactured in a small size and at a low cost.

Although a negatively charged image forming apparatus has been described with reference to FIG. 1, a positively charged image forming apparatus can be applied as long as the system uses a transfer roller. Further, in this embodiment, the charging member is moved up and down by using the pushing-up member and the spring means. However, the charging member may be moved up and down by a method using a cam or a solenoid. It is possible to obtain an effect.

[0029]

According to the present invention as described above,
Since the amount by which the charging member projects from the supporting member is reduced in association with the separation of the supporting member from the photosensitive member during the jam processing, the distance between the image carrier and the charging member is increased, and the charging member may be touched by a hand or the like. It is possible to prevent contact and prevent deterioration of the charging function.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus to which a charging member supporting device of the present invention is attached.

2A and 2B are diagrams showing the operation of the charging member support device of the present invention, in which FIG. 2A is a normal time, and FIG. 2B is a jam processing or maintenance time.

3A and 3B are views showing another embodiment of the present invention, in which FIG. 3A is a normal time, and FIG. 3B is a view showing a jam process or a maintenance process.

FIG. 4 is a perspective view showing a supporting portion of a transfer roller.

FIG. 5 is a diagram showing a main part of still another embodiment of the present invention,
FIG. 6A is a diagram illustrating a normal time, and FIG. 6B is a diagram illustrating a jam processing time or a maintenance time.

6 is a main part perspective view showing a modified example of the embodiment of FIG.

[Explanation of symbols]

 2 image carrier 6 charging member (transfer roller) 8 support member 84 spring means 85 pushing member 88 guides D1, D2 amount by which the charging member projects from the support member

Claims (6)

[Claims] 1. A charging member supporting device in an image forming apparatus, comprising: a charging member in contact with the image bearing member; and a supporting member supporting the charging member, wherein the supporting member contacts the charging member with the image bearing member. The image forming apparatus is movable between a contact position and a separated position, and the amount of protrusion from the support member is larger when the charging member is in contact with the image carrier than when the charging member is separated. Charging device support device in. 2. The charging member in the image forming apparatus according to claim 1, wherein when the charging member is separated from the image carrier, the amount of protrusion of the charging member from the supporting member becomes negative. Support device. 3. The spring means, wherein the support member is swingable about a swing fulcrum, supports the charging member at a position distant from the swing fulcrum, and is movable toward and away from the charging member, and the spring. And a push-up member which can be moved toward and away from the means, and the push-up member contacts the spring means to press the spring means against the charging member when the charging member is in contact with the image carrier. 3. The charging member supporting device in the image forming apparatus according to claim 1, wherein when the member is separated from the image carrier, the spring member is separated from the charging member to separate the spring member from the charging member. 4. The charging member supporting device in the image forming apparatus according to claim 1, wherein the charging member is a transfer roller that transfers the image of the image carrier onto a recording material. . 5. The support member has a guide for supporting the shaft of the transfer roller, and when the transfer roller is separated from the image carrier, the lower end of the transfer roller does not contact the support member with the guide. The charging member supporting device in the image forming apparatus according to claim 4. 6. The apparatus for supporting a charging member in an image forming apparatus according to claim 4, wherein the supporting member also serves as a conveying unit that conveys the recording material after transfer.