JP2002174954A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device by which the lowering of the toner concentration of ink is prevented by returning toner removed from a squeeze roller back to the ink by dispersing the toner and also a printing quality is maintained by keeping the cleaning performance of the squeeze roller long. SOLUTION: In the image forming device of an electrophotographic system having a developing unit provided with a photoreceptive belt at which an electrostatic latent image is formed, a developing roller to supply the photoreceptive belt with the ink which is liquid developer and the squeeze roller driven by always coming into contact with the photoreceptive belt, the stuck toner of the ink to a cleaning roller for the cleaning of the squeeze roller in the developing unit is scraped off by a cleaning blade, and is returned back to the ink while dispersing scraped toner so as to be reproduced.

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 an electrophotographic copying machine, a laser printer, and a facsimile using an ink which is a liquid developer containing a toner.

[0002]

2. Description of the Related Art In copiers, printers, fax machines, and the like,
A so-called wet image forming apparatus capable of forming an electrophotographic color image using a liquid developer containing a toner, that is, ink, is widely used. 2. Description of the Related Art A conventional wet-type color image forming apparatus includes a photosensitive belt that travels with an electrostatic latent image formed on a lower surface, and a developing device disposed below the photosensitive belt. Such a developing device is generally provided with a developing roller that contacts the lower surface of the photoreceptor belt to wet-develop an electrostatic latent image, and is provided downstream from the developing roller when viewed from the running direction of the photoreceptor belt. A squeeze roller for pressing against the lower surface of the body belt to remove residual developer. After an image is formed by development, the developing roller is separated from the photoreceptor belt, and the squeeze roller is pressed against the photoreceptor belt at the rotation speed during development to wipe off the photoreceptor belt, thereby completing the development cycle.

Incidentally, the squeeze roller used in such an image forming apparatus must always be kept in a clean state in which toner contained in ink does not adhere. If the toner remains on the squeeze roller, the toner is directly pressed against the belt-shaped photoconductor, so that the squeeze roller is offset toward the photoconductor during development, causing serious printing defects. Such a phenomenon is more likely to occur as the development processing speeds up.

In order to solve such a problem, a cleaning roller is provided in contact with the surface of the squeeze roller, and a link mechanism is provided for moving the cleaning roller close to and away from the squeeze roller. A technique has been proposed in which the surface of the photoreceptor belt is surely cleaned by rotating the squeeze roller and then rotating the squeeze roller in reverse (Japanese Patent Application Laid-Open No. H11-249444).

After the development, the developing roller descends and separates from the photoreceptor belt, and the squeeze roller presses against the lower surface of the photoreceptor belt while maintaining the rotational speed during development to dry the photoreceptor belt. There is also proposed a technique for providing a means for reducing the traveling speed of the vehicle to more reliably perform cleaning (Japanese Patent Application Laid-Open No. H11-327408).

However, in the prior art as shown here, means for moving each roller close to and away from each other, means for rotating the rollers in reverse, and means for shifting the running speed of the photosensitive belt are used. Therefore, it is mechanically complicated and tends to hinder improvement in cycle time for high-speed development processing.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to disperse toner generated when dirt on a squeeze roller is dispersed, to return to the original ink, to prevent a decrease in the toner concentration of the ink, and to perform cleaning. An object of the present invention is to provide an image forming apparatus provided with a developing unit capable of maintaining cleaning performance of a squeeze roller for a long time and maintaining print quality by eliminating ink accumulation in a blade and a developer reservoir.

[0008]

The object of the present invention is to provide a photoreceptor belt on which an electrostatic latent image is formed, a developing roller which is disposed close to the photoreceptor belt and supplies ink as a liquid developer to the surface thereof. And a squeezing roller disposed downstream of the developing roller, the squeezing roller being constantly in contact with and driven by the photoreceptor belt. It is characterized in that the toner of the ink adhering to the cleaning roller for cleaning the roller is scraped by a cleaning blade, and the scraped toner is dispersed and returned to the original ink for reproduction. Is solved by the image forming apparatus described above.

In addition, a reservoir for receiving ink is provided below the cleaning blade, and a helical rotating in the reservoir to uniformly disperse the toner scraped by the cleaning blade into the ink. The problem is solved more advantageously by an image forming apparatus including a brush roller provided with a flock.

[0010] The present invention is also advantageously solved by an image forming apparatus in which the spiral flocking portion is formed as a single spiral body formed to rotate in the same direction.

[0011] The present invention is also advantageously solved by an image forming apparatus in which the spiral flocking portion is a spiral body formed so as to rotate in mutually opposite directions with an intermediate border.

Further, the object of the present invention is further advantageously solved by an image forming apparatus in which a plurality of drain holes for collecting toner and ink are formed at the bottom of the reservoir.

A drain hole formed at the bottom of the reservoir is formed at the middle and the most downstream side when toner and ink are moved by the rotation of the single spiral flocking portion, and the hole diameter at the most downstream side is formed. Is more advantageously solved by an image forming apparatus selected to be larger.

An image formed at both ends when the toner is moved by rotation of a spiral flocked portion formed so that a drain hole formed at the bottom of the reservoir turns in the opposite direction from the intermediate position. It is more advantageously solved by a forming device.

Prior to disclosing the operation and features of a developing unit using ink as a liquid developer according to the present invention, a schematic configuration of a wet image forming apparatus using such a developing unit will be disclosed with reference to FIG. . FIG. 2 shows a main part of the overall view of the image forming apparatus. In FIG. 2, a photoreceptor belt 13 is disposed at the center of the apparatus, and is rotated by a belt drive roller 12. In the lower part of the belt, there are four sets of L for forming a latent image.
There is a D unit 10 and one developing unit 18.
The drying unit 11 is disposed downstream of the developing unit 18 on the photoreceptor belt 13, and the transfer roller 14 and the fixing roller 15 are disposed further above.

The operation of the apparatus shown in FIG. 2 will be disclosed. During printing or image formation, the photosensitive belt 1 in the center of the apparatus
Reference numeral 3 is rotated by a belt drive roller 12 in the direction of the arrow in the figure. The photoreceptor belt 13 is charged up to a predetermined potential by the main charger 17, and a latent image is formed thereon by the LD unit 10. The developing process is performed while the photosensitive belt on which the latent image is formed passes through the developing unit 18. The developed image is evaporated into a film on the photosensitive belt by evaporating the solvent in the ink in the drying unit 11. The image is transferred once to the transfer roller 14 and then transferred and fixed to the print medium by the fixing roller 15. As a result, a printing medium on which printing or image formation is performed is obtained.

According to the developing unit of the image forming apparatus according to the present invention, the following effects are obtained as a result of the above-described configuration. That is, the toner on the surface of the cleaning roller from which the dirt on the squeeze roller has been electrostatically removed is scraped off by the cleaning blade. The toner scraped off by the cleaning blade is regenerated into the original ink while being dispersed by the brush roller, preventing the ink concentration from lowering and improving the cleaning performance of the squeeze roller by extending the life of the blade. This can contribute to stable image quality improvement.

[0018]

FIG. 1 shows a basic structure of an embodiment of a developing unit 18 constituting a main part of the present invention. The developing unit shown in FIG. 1 includes a developing roller 1 for supplying ink onto a photosensitive belt 8 on which a latent image is formed in advance to form an image, and a cleaning blade 6 is pressed against the roller 1. ing.

The squeeze roller 2 is disposed downstream of the photosensitive belt 8 in the traveling direction so as to be pressed against the lower surface of the photosensitive belt 8. The cleaning roller 3 is disposed at a small gap with respect to the squeeze roller 2, and the cleaning blade 5 is also pressed against the cleaning roller 3. The cleaning roller 3 is configured to charge a negative charge, and electrostatically attracts toner adhering to the surface of the squeeze roller 2.

Below the cleaning blades 5 and 6, which are pressed against the developing roller 1 and the cleaning roller 3, respectively, a reservoir 7 for storing collected toner as shown in FIG. 3 is provided. The reservoir 7 includes a cleaning blade 6 attached to the developing roller 1 and a cleaning blade 5 attached to the cleaning roller 3.
Are arranged along the longitudinal direction, and function as ink and toner receivers.

A brush roller 4 having a shape in which a flocked portion is spirally formed on a shaft as shown in FIG. 4A is disposed so as to overlap with these cleaning blades 5 and 6. This brush roller 4 has a drain hole F as shown in FIG.
It is rotatably housed in a reservoir 7 formed at locations 2 and F3.

The operation of the developing unit configured as described above is as follows. When the ink is supplied to the developing roller 1, an image is formed on the photosensitive belt 8 on which the latent image is formed. The image is squeezed by the squeeze roller 2 which is pressed against the photoreceptor belt 8, and the image on the photoreceptor is formed into a film and is temporarily attached. At this time, the toner in the ink adheres to the surface of the squeeze roller 2 as well. The toner thus adhered is electrostatically moved to the side of the cleaning roller 3 to which the negative charge is applied, and the toner adhered to the surface of the squeeze roller 2 is removed.

The toner moved to the cleaning roller 3 in this manner is applied to the cleaning blade 5
Is scraped by The toner scraped by the cleaning blade 5 is transferred to the brush roller 4 in the reservoir 7.
And the ink is returned to the original ink and dispersed. At this time, since the brush roller 4 has a shape in which one spiral flocking portion is wound around the shaft as shown in FIG. 4A, the brush roller 4 rotates rightward in the reservoir 7 as shown in FIG. Since ink flows in the direction of the arrow, a difference in ink height occurs at both ends of the brush. Therefore, in FIG. 3, the drain hole of the reservoir 7 is closed at F1 which is the upstream portion of the ink flow, and the middle F2 is a normal size drain hole, and the drain hole diameter of F3 at the downstream portion is increased. As a result, the height of the ink can be made uniform in the axial direction in the reservoir 7, and the ink can be drained smoothly. That is, a feature is obtained in which the scraped toner can be dispersed as uniformly as possible and the drain can be smoothly drained.

As described above, the toner scraped off by the cleaning blade 5 is returned to the original ink while being uniformly diffused, thereby preventing the ink concentration from lowering and allowing the scraped toner to partially stay. Can be prevented. As a result, the life of the cleaning blade 5 can be extended, and image defects due to poor cleaning of the squeeze roller 2 can be eliminated, and a stable image can be obtained.

Hereinafter, the operation of this embodiment will be described. In the developing unit of FIG. 1, a developing roller 1 for supplying ink to a photoreceptor belt rotates in a direction indicated by an arrow in FIG. By such an operation, an image is formed on the photosensitive belt 8 on which the latent image is formed. The image thus formed is pressed against the photoreceptor belt 8 and the squeeze roller 2 that is driven evaporates the solvent in the ink to some extent. At this time, the toner on the photosensitive belt 8 adheres to the squeeze roller 2. In order to remove the toner, a negative charge is applied to the cleaning roller 3 to electrostatically move the toner to the surface of the cleaning roller 3.

The toner transferred onto the cleaning roller 3 is scraped off by the cleaning blade 5, and the surface of the cleaning roller 3 is always kept free from toner adhesion. The toner scraped off by the cleaning blade 5 is agitated by the brush roller 4 overlapping the cleaning blade 5. At this time, the ink in the reservoir 7 flows in the direction of the arrow in FIG. As a result, there is a difference in ink height at both ends in the reservoir 7. In consideration of such a height, the drain hole is closed in the upstream of the ink flow, that is, in the F1 portion of FIG. 3, and the hole diameter is increased in the downstream F3, so that the ink height in the reservoir 7 is uniform. It can be said. The regenerated ink in which the toner is evenly dispersed is used for the drain hole F.
2 and F3.

FIG. 5 shows another embodiment of the present invention. In this embodiment, a configuration is devised in which the toner scraped by the cleaning blade 5 that is in pressure contact with the cleaning roller 3 is less likely to stay in the reservoir. The inner shape of the reservoir 20 slightly overlaps the outer shape of the brush roller 19 to reduce the space where the scraped toner remains. As a result, it becomes possible to effectively disperse the toner in the reservoir 20, and it is possible to recover the ink in which the toner is more uniformly dispersed.

In still another embodiment, the toner scraped by the cleaning blade 5 is dispersed by the brush roller 4, and then the ink is drained smoothly, and the toner scraped by the cleaning blade 5 is discharged to the reservoir 7 or It is devised so that it does not easily remain in the inside of the substrate 20. As in the brush roller shown in FIG. 4B, the direction in which the flocked portion of the brush is formed in a spiral shape is arranged in a direction opposite to the center of the roller. By rotating the brush having such a structure as shown by the curved arrow, the ink in the reservoir receives a propulsive force from the center toward both ends,
The drain hole of the reservoir 7 or 20 can secure a uniform liquid level by providing only F1 and F3 on both sides in FIG. By employing such a structure, the toner scraped by the cleaning blade 5 can be more uniformly dispersed, and the ink can be drained more smoothly.

[0029]

According to a method in which toner adhered to a squeeze roller is electrostatically moved to a cleaning roller by a developing unit in this type of image forming apparatus, and a cleaning blade removes dirt from the cleaning roller, the scraping is performed. The toner tends to accumulate in the reservoir or adhere to the blade and remain. As a result, a decrease in the ink density occurred, or the cleaning performance deteriorated due to the toner adhering to the blade, the cleaning roller was contaminated with toner, and further, the toner adhered to the squeeze roller. Print defects were also likely to occur in images. According to the configuration of the present invention, when the toner scraped by the cleaning blade is returned to the ink, the toner is uniformly dispersed by the rotation of the brush roller having the spiral flocked portion, and is provided at the bottom of the ink reservoir. Is forcibly discharged from the drain hole. Therefore, the cleaning roller can be easily cleaned, toner adhesion to the squeeze roller can be eliminated, print quality can be expected to be improved, and the ink having uniform toner dispersion can be easily collected.

[Brief description of the drawings]

FIG. 1 is a side view illustrating a configuration of a developing unit in an image forming apparatus according to the present invention.

FIG. 2 is a side view showing an example of the entire configuration of the image forming apparatus according to the present invention.

FIG. 3 is a perspective view showing a configuration of a reservoir applicable to the developing unit shown in FIG.

FIG. 4 is a front view showing a shape (4-a) of a brush roller used in the present invention and a shape (4-b) of a modified example thereof.

FIG. 5 is a side view illustrating a configuration of a developing unit in an image forming apparatus according to another embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 developing roller 2 squeeze roller 3 cleaning roller 4 brush roller 5 cleaning blade 6 cleaning blade 7 reservoir 8 photosensitive belt 9 ink 10 LD unit 11 drying unit 12 belt drive roller 13 photosensitive belt 14 transfer roller 15 fixing roller 16 transfer backup roller 17 Main Charger 18 Developing Unit 19 Brush Roller 20 Reservoir

Claims (7)

[Claims] A photosensitive belt on which an electrostatic latent image is formed;
A developing roller which is disposed adjacent to the photoreceptor belt and supplies ink as a liquid developer to the surface thereof; and a squeeze roller which is disposed downstream of the developing roller and is always in contact with and driven by the photoreceptor belt. In an electrophotographic image forming apparatus having a developing unit having: a cleaning roller for cleaning the squeeze roller in the developing unit, scraping ink toner adhering with a cleaning blade,
An image forming apparatus characterized in that the scraped toner is dispersed in the original ink while being dispersed and reproduced. 2. A helical rotating member inside the reservoir for dispersing the toner scraped by the cleaning blade into the ink, the reservoir being provided below the cleaning blade for receiving ink. The image forming apparatus according to claim 1, further comprising a brush roller having a flocked portion. 3. The image forming apparatus according to claim 2, wherein the spiral flocking portion is formed as a single spiral body formed to rotate in the same direction. 4. The image forming apparatus according to claim 2, wherein the helical flocking portion is a helical body formed so as to rotate in opposite directions with respect to a middle. 5. The image forming apparatus according to claim 1, wherein a plurality of drain holes for collecting toner and ink are formed at a bottom of the reservoir. 6. A drain hole formed at the bottom of the reservoir is formed at an intermediate position and a most downstream position when toner and ink are moved by rotation of a single spiral flocking portion, and a diameter of the hole at the most downstream position. The image forming apparatus according to claim 5, wherein the image forming apparatus is selected so as to increase. 7. A drain hole formed at the bottom of the reservoir is formed at both ends when toner is moved by rotation of a spiral flocked portion formed to rotate in an opposite direction from an intermediate position. 6. The method according to claim 5, wherein
4. The image forming apparatus according to claim 1.