JPH11249444A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of maintaining the image quality for a long period. SOLUTION: The device P is provided with a photoreceptor 3 having a surface on which an electrostatic latent image is formed, a developing roller 4 which comes close to the photoreceptor 3 so as to supply the liquid developer to the surface of the photoreceptor 3, and a squeezing roller 7 which comes into contact with the photoreceptor 3 and also which is arranged on the downstream side of the developing roller 4. In this case, a cleaning roller 1 which comes into contact with the surface of the squeezing roller 7 is installed near the squeezing roller 7. Thus, the developing roller 4 is cleaned by the cleaning roller 1, simultaneously, the squeezing roller 7 is also cleaned by the roller 1. Thus, the solidified developer on the surfaces of the developing roller 4 and the squeezing roller 7 is removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus such as a printer, a facsimile, a copying machine, etc., utilizing an electrophotographic process using a liquid developer.

[0002]

2. Description of the Related Art Conventionally, in a wet type image forming apparatus in which a developer containing toner is supplied to a photoreceptor to perform development, an electrostatic latent image formed on a belt-like photoreceptor is developed by a developing roller. The developer is supplied to the gap between the belt and the photoreceptor by a developer supplied from a developer supply outlet. During this development, excess liquid developer adhering to the belt-shaped photoconductor is squeezed by the squeeze roller. The squeeze roller is rotatably supported by a squeeze support, and the squeeze support is mounted via a compression coil spring on a movable table that freely moves up and down toward the belt-shaped photoconductor. Therefore, when the moving table is close to the belt-shaped photoconductor, the squeeze roller is pressed against the belt-shaped photoconductor with a larger pressing force due to the elasticity of the compression coil spring, and the moving table is moved from the belt-shaped photoconductor within a range where the compression coil spring reaches. When separated, the squeeze roller is pressed against the belt-shaped photosensitive member with a small pressing force by the compression coil spring.

Normally, the movable table is close to the belt-shaped photoconductor, and the squeeze roller is pressed against the belt-shaped photoconductor by a compression coil spring with a strong force, and is driven to rotate in the same direction as the moving direction of the surface of the belt-shaped photoconductor. Meanwhile, squeeze (squeezing of excess liquid developer) is performed. As a result, the image on the belt-shaped photoreceptor becomes a film, and after a drying process, is transferred to paper and printed.

When the squeezing operation described above is performed, excess liquid developer squeezed by the squeeze roller from the belt-shaped photoconductor stays in a gap upstream of a contact portion between the belt-shaped photoconductor and the squeeze roller. If the apparatus is stopped and left in this state, the accumulated liquid developer is dried and solidified, which has an adverse effect such as generation of stains at the next printing.

For this reason, conventionally, in this type of image forming apparatus, as disclosed in Japanese Patent Application Laid-Open No. Hei 5-273867, the squeeze roller is maintained at a constant gap with respect to the photoreceptor and rotated in the opposite direction. In general, an excess developer is removed without disturbing the developed toner image. Specifically, immediately before the image forming apparatus is stopped, the moving platform holding the squeeze supports at both ends of the squeeze roller is moved away from the belt-shaped photoconductor, the compression coil spring is extended, and the surface of the belt-shaped photoconductor of the squeeze roller is extended. Reduce the pressing force on the Thus, the squeeze roller can be driven and rotated in a direction opposite to the moving direction of the surface of the belt-shaped photoconductor from a state of being driven and rotated in the same direction as the driving direction of the belt-shaped photoconductor. Thus, by rotating the squeeze roller in the opposite direction, the liquid developer can be efficiently removed from the belt-shaped photoconductor.

Japanese Patent Application Laid-Open No. 58-18666 proposes an invention in which a developing solution on the surface of a squeeze roller is scraped off by a blade. This is because if the liquid developer has adhered to the squeeze roller, it is inconvenient to remove excess liquid developer from the belt-shaped photoconductor.

[0007]

However, the above conventional example has the following disadvantages. That is, as described above, when the squeeze roller to which the liquid developer is attached is left for a long time, the developer on the squeeze roller is dried,
There has been a problem that the toner adheres to the roller surface to deteriorate the performance, and a black streak-like image defect occurs.

In order to solve this problem, even when the blade is brought into contact with the squeeze roller, it is actually difficult to completely remove the developer adhered during printing only with the blade, and the remaining developer is hardly removed. There is a problem that if the surface is dried by being left, it cannot be removed.

As described above, in the above-described conventional image forming apparatus, it is difficult to maintain the performance of the squeeze roller until the life of the developing roller and other components, and a cleaning operation by a user or a maintenance person is required periodically. There was a disadvantage that it was.

[0010]

The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus.
It is an object of the present invention to provide an image forming apparatus capable of maintaining image quality for a long period of time.

[0011]

In order to achieve the above object, according to the first aspect of the present invention, there is provided a photoconductor having an electrostatic latent image formed on a surface thereof, and a photoconductor in proximity to the photoconductor. An image forming apparatus including a developing roller for supplying a liquid developer to the surface of the squeeze roller and a squeeze roller that contacts the photosensitive member and is disposed downstream of the developing roller. The cleaning roller is provided in contact with the surface.

With the above configuration, the cleaning roller cleans the developing roller and the squeeze roller at the same time. For this reason,
The developer solidified on the surfaces of the developing roller and the squeeze roller is removed.

According to the second aspect of the present invention, the photosensitive member has a belt-like configuration, and the other configurations are the same as those of the first aspect.

According to the third aspect of the present invention, the cleaning roller contacts the developing roller and rotates in the same direction, and the other configuration is the same as that of the first or second aspect.

According to a fourth aspect of the present invention, the squeeze roller has a configuration in which a rubber layer having an elastic body is provided on the surface, and the other configuration is the same as that of the first, second or third aspect.

According to a fifth aspect of the present invention, the rubber layer has a configuration of urethane, ethylene-propylene diene monomer or nitrile rubber, and the other configuration is the same as the fourth aspect of the invention.

Further, in the invention according to the sixth aspect, the cleaning roller is configured to contact the squeeze roller for a predetermined time after the end of the printing process, and the other configurations are configured as the first, second, third, fourth or fifth aspect. It is the same as the invention of the above. With such a configuration, during image formation, the squeeze roller is driven by the movement of the belt-shaped photoconductor. At this time, the cleaning roller is separated so as not to hinder the rotation of the squeeze roller. On the other hand, after image formation, the cleaning roller contacts the squeeze roller to perform cleaning.

[0018]

Next, an image forming apparatus according to the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of the present invention. The image forming apparatus P of the present invention includes a belt-shaped photoconductor 3 and a developing roller 4 that supplies a liquid developer to the surface of the belt-shaped photoconductor 3. This developing roller 4 is in contact with the belt-shaped photoconductor 3. At a position facing the developing roller 4 with the belt-shaped photoconductor 3 interposed therebetween, the first
Backup roller 5 is provided. The first backup roller 5 sandwiches the belt-shaped photoconductor 3 together with the developing roller 4 to ensure the supply of the liquid developer from the developing roller 4 to the belt-shaped photoconductor 3, This is to ensure transportation.

The image forming apparatus P has a rotational force urging means (not shown) for urging the squeeze roller 7 to rotate.
And a support unit 13 for supporting the developing roller and the cleaning roller, and a cam mechanism (not shown) as a movement urging mechanism for urging the movement of the support unit 13.
Further, the image forming apparatus P includes a squeeze support unit 15 that holds the squeeze roller 4 and is movably mounted in a direction to approach and separate from the belt-shaped photoconductor 3.
Between the support unit 13 and the squeeze support unit 15, a compression coil spring (shown in the drawing) as two types of elastic bodies having different natural lengths for urging the squeeze roller 7 to press the belt-shaped photoconductor 3 side. Abbreviation) is inserted.

The surface of the belt-shaped photoconductor 3 is coated with a photoconductor so that an electrostatic latent image is formed by light irradiation. A light source (not shown) is provided upstream of the belt-shaped photoconductor 3, and light is emitted from the light source toward the belt-shaped photoconductor 3 in accordance with an image to be formed. Generally, a laser light source is used as this light source. Belt-shaped photoreceptor 3
Is charged by a charger (not shown), and is irradiated with light thereafter, so that a potential difference is generated between the region and the region not irradiated with light. The belt-shaped photoconductor 3 has a loop shape.

In the vicinity of the developing roller 4, a developer supplying means 2 is provided. The developer supply unit 2 takes in the developer from a developer storage unit (not shown) and
The liquid developer is supplied to the surface of the liquid developer. Specifically, a predetermined pipe-shaped member is provided on the upstream side of the contact position between the developing roller 4 and the first backup roller 5, and the liquid developer is supplied from the pipe-shaped member to the developing roller 4. You.

The squeeze roller 7 is disposed downstream of the developing roller 4 in contact with the belt-shaped photosensitive member 3. A second backup roller 6 is located at a position facing the squeeze roller 7 with the belt-shaped photoconductor 3 interposed therebetween.
Are arranged. This second backup roller 6
Holds the belt-shaped photoconductor 3 together with the squeeze roller 7. The belt-shaped photoconductor 3 moves in the direction of the arrow in the figure, and an electrostatic latent image is formed on the surface.

In the vicinity of the squeeze roller 7, a predetermined blade 8 is provided. The blade 8 is for removing the liquid developer adhering to the surface of the squeeze roller 7. The surface of the squeeze roller 7 is made of an elastic rubber layer. The material of the rubber layer is, for example, urethane, EPDM or nitrile rubber.

The cleaning roller 1 is disposed near the developing roller 4 and the squeeze roller 7. The cleaning roller 1 is for removing the liquid developer adhering to the developing roller 4 and the squeeze roller 7. The cleaning roller 1 is a roller wound with a nonwoven fabric such as cotton. However, besides this, a foam roller made of urethane or a brush roller made of acrylic, nylon, rayon or the like may be used.

Next, the operation and operation of the image forming apparatus P according to the present invention configured as described above will be described. The belt-shaped photoconductor 3 has a region where light is not irradiated, that is, a non-image portion has a potential of about 600 V, and a light-irradiated image portion has a potential of about 50 to 120 V. . Then, the liquid developer in which the toner and the carrier are mixed is supplied to the surface of the developing roller 4 from the developing material supply means 2, and the developing roller 4 rotates while rotating in the direction of the arrow in the drawing.
A liquid layer of the liquid developer is formed on the surface.

The developing roller 4 and the surface of the belt-shaped photoconductor 3 face each other with a distance of about 100 μm to 200 μm, and the belt-shaped photoconductor 3 is provided with a first backup roller 5 and a second backup roller. It is transported along the rollers 6. Thus, the electrostatic latent image on the surface of the belt-shaped photoconductor 3 is developed by the liquid developer on the developing roller 4.

The toner concentration of the toner image immediately after development on the belt-shaped photosensitive member 3 is about 20 to 50% with respect to the total amount of the liquid developer. Then, as the belt-shaped photoconductor 3 advances, excess liquid developer is removed by the squeeze roller 7. At this time, the squeeze roller 7 is about 1-2 kgf / cm
Contact at pressure of ² . For this reason, the excess carrier is mainly removed, and the concentration of the toner remaining on the surface of the belt-shaped photoconductor 3 is about 50 to 80%. At this time, the toner itself changes from a liquid to a semi-solid due to the cohesive force between the toners, and is semi-fixed on the belt-shaped photoconductor 3.

As described above, the squeeze roller 7 is a rubber roller having on its surface a rubber layer having an elastic material such as urethane, EPDM, or nitrile rubber. The hardness of the rubber layer is 30 to 60 degrees Shore, and the contact pressure with respect to the belt-shaped photoconductor 3 is 200 to 50 per unit length.
0 gf / cm. However, these values are only examples,
It is necessary to select an appropriate roller according to the size and length of each roller used.

Through the above steps, an appropriate toner image is formed on the surface of the belt-shaped photosensitive member 3. Then, the belt-shaped photoconductor 3 is further conveyed, and is transferred to a transfer unit (not shown).
The toner image is transferred to the printing paper. Then, after the toner image is transferred, the belt-shaped photoconductor 3 is transported again, and
It is used for the next image formation.

Incidentally, as described above, the developing roller 4
And the squeeze roller 7 directly contacts the liquid developer. For this reason, the surplus liquid developer adheres to the surfaces of the developing roller 4 and the squeeze roller 7. Therefore, the surface is cleaned by the cleaning roller 1.

The cleaning roller 1 is, as described above, a roller wound with a nonwoven fabric made of cotton fiber or the like, or a urethane foam roller, or a brush roller made of acrylic, nylon, rayon or the like. Then, it rotates while being in contact with the developing roller 4 and the like, and rubs the surfaces of the developing roller 4 and the squeeze roller 7 facing each other to remove the toner fixed on the surfaces.

As described above, in this embodiment, the cleaning of the developing roller 4 and the squeeze roller 7 is performed simultaneously by one cleaning roller 1. For this reason, there is a special effect that the cleaning operation can be performed more efficiently than when the liquid developer is removed only by the blade 8 without increasing the number of parts.

Next, a second embodiment of the present invention will be described. In the present embodiment, the cleaning roller 1 does not contact the squeeze roller 7 during the developing process. The reason is that the squeeze roller 7 is driven in contact with the belt-shaped photoconductor 3, and when the rotational load torque is increased, the squeeze roller 7 cannot rotate at the same peripheral speed as the belt-shaped photoconductor 3, and the toner image formed on the surface is It is because it disturbs.

For this reason, the cleaning of the squeeze roller 7 is performed after the end of the printing process. Specifically, the cleaning roller 7 is supported by the link structure 10 so that the rotation shaft can move. That is, the cleaning roller 1 is configured to swing around the developing roller 4. The developing roller 4 and the cleaning roller 1 are supported by a support unit 13 and move up and down at the same time.

The squeeze roller 7 and the blade 8 are supported by the same squeeze support unit 15,
The squeeze support unit 15 that supports the squeeze roller 7 and the like can also move up and down. Therefore,
Support unit 13 for supporting the above-described developing roller 4 and the like
And the squeeze support unit 15 that supports the squeeze roller 7 and the like can move up and down independently of each other.

The operation at the end of the printing process will now be described with reference to FIGS.
As shown in FIG. FIG. 2 shows a state in which the developing roller 4 is retracted from the developing position and is separated from the belt-shaped photoconductor 3. On the other hand, the squeeze roller 7 is in contact with the belt-shaped photoconductor 3. This is because the belt photoreceptor 3 can be used even after the printing process.
The liquid developer may remain on the upper part, and this is because the squeeze roller removes the liquid developer. In order to remove the remaining liquid developer, the squeeze roller 7 rotates in a direction opposite to the conveying direction of the belt-shaped photoconductor.

The cleaning roller 1 is in contact with the squeeze roller 7 when the liquid developer on the surface of the belt-shaped photosensitive member 3 is removed by the squeeze roller 7. At this time, since the squeeze roller 7 and the cleaning roller 1 are both rotating in the same direction (clockwise in FIG. 2), the surfaces of the squeeze roller 7 and the cleaning roller 1 are in contact with each other at the contact portion between them. While moving in the opposite direction. Thus, the liquid developer is efficiently removed from the surface of the squeeze roller 7.

The blade 8 described above is provided near the squeeze roller 7. This blade 8
Has the same length as the entire length of the squeeze roller 7 and contacts the squeeze roller 7 as necessary. Then, the liquid developer adhering to the surface of the squeeze roller 7 is removed. The blade 8 has elasticity and can remove solidified developer to some extent.

The cleaning roller 1 removes the liquid developer from the squeeze roller 7 and at the same time comes into contact with the developing roller 4 to redisperse and remove the liquid developer on the developing roller 4. By performing the above operation for about 0.5 to 1.5 seconds, the removal of the liquid developer is completed.

After the removal of the liquid developer is completed, both the developing roller 4 and the squeeze roller 7 are separated from the belt-shaped photosensitive member 3, as shown in FIG. Each component is on standby until the next print command is issued.

FIG. 4 is a cross-sectional view showing a state during normal printing according to the present embodiment. As shown in FIG. 4, during normal printing, the cleaning roller 1 is
, But only with the surface of the developing roller 4.
Therefore, the cleaning roller 1 cleans the surface of the developing roller 4.

[0043]

As described above, according to the present invention, in the image forming apparatus, the cleaning roller is provided, and the liquid adhered to the surfaces of the developing roller and the squeeze roller by rubbing both surfaces of the developing roller and the squeeze roller. By redispersing and removing the developer (toner), an excellent effect that image quality can be maintained for a long time is produced.

Further, since both the developing roller and the squeeze roller can be cleaned by one cleaning roller, the space efficiency in the image forming apparatus can be improved, and the increase in the number of parts for cleaning can be minimized. Can be suppressed.

The cleaning roller contacts the developing roller and rotates in the same direction. For this reason, at the contact point between the cleaning roller and the developing roller, the two rollers have peripheral velocities opposite to each other. For this reason,
The developer remaining on the surface of the developing roller can be efficiently removed.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing a second embodiment of the present invention,
This shows a state where the developing roller is separated from the belt-shaped photoconductor.

3 is a cross-sectional view illustrating the image forming apparatus disclosed in FIG. 2, showing a state in which a squeeze roller is separated from a belt-shaped photosensitive member.

4 is a cross-sectional view illustrating the image forming apparatus disclosed in FIG. 2, showing a state in which a developing roller and a squeeze roller are in contact with a belt-shaped photoconductor, and a cleaning roller is separated from the squeeze roller.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cleaning roller 2 Developer supply means 3 Belt-shaped photoreceptor 4 Developing roller 7 Squeeze roller 8 Blade

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[Procedure amendment]

[Submission date] February 1, 1999

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 1

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction contents]

[0011]

In order to achieve the above object, according to the first aspect of the present invention, there is provided a photoconductor having an electrostatic latent image formed on a surface thereof, and a photoconductor in proximity to the photoconductor. An image forming apparatus comprising: a developing roller for supplying a liquid developer to a surface of the developing roller; and a squeeze roller which is in contact with the photosensitive member and is disposed downstream of the developing roller. Contact the surface of
It has a cleaning roller that touches
Move the approaching roller close to and away from the squeeze roller.
And a link mechanism for causing the link mechanism to be provided .

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction contents]

With the above configuration, the cleaning roller cleans the developing roller and the squeeze roller at the same time. For this reason,
The developer solidified on the surfaces of the developing roller and the squeeze roller is removed. In addition, squeeze rollers
Cleaning roller can be separated from photoconductor
Rotating torque to the rotating squeeze roller.
I can't. Therefore, the image on the photoconductor is not disturbed.

Claims (6)

[Claims] A photosensitive member having an electrostatic latent image formed on a surface thereof;
An image forming apparatus including: a developing roller that supplies a liquid developer to the surface of the photoconductor in proximity to the photoconductor; and a squeeze roller that contacts the photoconductor and is disposed downstream of the developing roller. 3. The image forming apparatus according to claim 1, further comprising a cleaning roller in contact with the surface of the squeeze roller near the squeeze roller. 2. The image forming apparatus according to claim 1, wherein said photosensitive member is in a belt shape. 3. The image forming apparatus according to claim 1, wherein the cleaning roller contacts the developing roller and rotates in the same direction. 4. The squeeze roller has a rubber layer having an elastic body on a surface thereof.
Or the image forming apparatus according to 3. 5. The image forming apparatus according to claim 4, wherein said rubber layer is made of urethane, ethylene-propylene diene monomer or nitrile rubber. 6. The image forming apparatus according to claim 1, wherein the cleaning roller contacts the squeeze roller for a predetermined time after the end of the printing process.