JPH0132050Y2 - - Google Patents

Description

[Detailed description of the invention] Technical field This invention brings a latent image formed on an endless photoreceptor belt that is passed around a plurality of rollers into contact with the photoreceptor belt at a portion away from the rollers. The present invention relates to a support device for the endless photoreceptor belt of an electrophotographic apparatus that performs development.

Prior Art The developing section of an electrophotographic apparatus using an endless photoreceptor belt stretched around a plurality of rollers includes: (a) a developing sleeve is provided facing the rollers;

(b) Place the developing sleeve opposite the photoreceptor belt between the rollers.

Two methods have been adopted.

Method (a) is not affected by the vibration of the photoconductor belt, but the position where the developing section is placed is limited, and in the case where the developing sleeve and photoconductor come into contact, even a slight shift in position will cause the sleeve and photoconductor to There is a drawback that the mutual pressing force between the photoreceptor and the photoreceptor changes significantly, which may damage the photoreceptor.

On the other hand, the latter does not have such drawbacks, but in conventional devices of this type, the distance between the developing sleeve and the photoconductor support roller is long, so vibrations caused by the belt drive and the belt's contact with the developing section may affect the image. In addition, the developing device had to be moved in order to adjust the width of the developing nip, which caused the device to become bulky.

Purpose This invention solves the above-mentioned drawbacks of the conventional electrophotographic apparatus that uses an endless photoreceptor belt and performs development by bringing the developing sleeve into contact with the photoreceptor belt in the middle of the support roller. It is an object of the present invention to provide an endless photoreceptor belt support device which allows the width of a developing nip to be easily adjusted without being affected.

Configuration In order to achieve the above object, the present invention provides a member that contacts the photoreceptor belt in a mutually movable manner at two positions sandwiching the contact position of the developing sleeve in the vicinity thereof, such as a roller or a member that slides with low friction. established,
The present invention is characterized in that at least one of the contact portions is provided so that its position can be adjusted.

Hereinafter, the present invention will be explained in detail based on drawings showing embodiments thereof.

In the embodiment shown in FIG. 1, an endless photoreceptor belt 1 is stretched around a drive roller 2, a guide roller 3, a tension roller 4, and a position adjustment roller 5, which will be explained in detail later. move. Around the photoreceptor belt 1, in the order of its moving direction, a charger 6, an exposure device 7, a developer 8,
A transfer charger 9 and a cleaning device 10 are provided, and copying is performed by a known method.

The developing sleeve 11 of the developing device 8 is located between the drive roller 2 and the position adjustment roller 5 which is provided at a short distance in front of the photoreceptor belt 1 in the moving direction of the photoreceptor belt 1.
are provided opposite to each other so as to be able to come into contact with and separate from each other.

The position adjustment roller 5 is adjustable in position perpendicularly to the photoreceptor belt 1, and is placed in a position where the photoreceptor belt 1 comes into contact with the developing sleeve 11 during development when copying an original smaller than the maximum original size. During development, the photoreceptor belt 1 can be moved to a position away from the developing sleeve 11, and the photoreceptor belt 1 can be moved away from the developing sleeve 11.
The nip width can be adjusted to any desired value. Further, the position adjustment roller 5 is pressed against the photoreceptor belt 1 by a compression spring 12, and if the photoreceptor belt 1 moves from a predetermined position to the inside of the belt loop, it applies tension to the photoreceptor belt 1 to maintain the predetermined position. It is designed to be retained.

Since this device is constructed as described above, vibrations of the photoreceptor belt caused by driving the photoreceptor belt 1 are absorbed by the short distance between the position adjustment roller 5 and the drive roller 2, and the original image sleeve 11
Vibration due to contact with the photoreceptor belt 1 is also less likely to occur, and this does not adversely affect the exposed area, making it possible to obtain high-quality copies without image blurring. Furthermore, when copying an original smaller than the maximum original size, the photoreceptor belt 1 is separated from the developing sleeve 11 in the non-developing area, and excess toner adheres to the photoreceptor belt 1, putting an unnecessary burden on the cleaning device 10. In addition, wear of the photoreceptor 1 can be delayed. Further, by displacing the position adjustment roller 5, the nip width of the developing sleeve can be easily adjusted.

In another embodiment shown in FIG.
is a drive roller 2, three guide rollers 3, a tension roller 4, and a roller 2 held by one holding member.
A charging device 6, an exposure device 7, a developing device 8, a transfer charger 9, and a cleaning device 10 are provided around the position adjustment roller 5.

In this embodiment, the developing sleeve 11 of the developing device 8 is located between the drive roller 2 and the next guide roller 3 and at a distance from both rollers. Two position adjustment rollers 5, which contact the inner surface of the photoreceptor belt 1 near both sides of the photoreceptor belt 1 at the position where it contacts the developing sleeve 11, are each pivotably supported at the tips of the bifurcated arms 13a of the roller holding member 13. has been done. The roller holding member 13 is movable in the AB direction by engaging the guide groove 13b with the guide pin 14, and the belt position is displaced by a position adjusting device (not shown) as explained in the previous embodiment. The position can be adjusted as shown.

The effect of this device is similar to that of the previous embodiment.

In the above two embodiments, rollers were used as position adjustment members for pressing the photoreceptor belt on both sides of the contact portion of the developing sleeve 11, but the rollers are not necessarily limited to this, and the photoreceptor belt can be moved with less friction. It is also possible to use a member that allows the belt to slide freely. FIGS. 3 and 4 show a sleeve opposing plate 15 made of such a material in place of the positioning roller 5 of the embodiment shown in FIGS. 1 and 2, respectively.
An example is shown below.

Effects As described above, according to the present invention, the vibration of the photoreceptor belt is reduced at the part of the developing section that contacts the developing sleeve, and the vibration of the photoreceptor belt that is generated due to the contact between the developing sleeve and the photoreceptor belt in the conventional device is reduced. Since the vibrations transmitted to the image forming apparatus and the like are also significantly reduced, transfer and exposure blurring is prevented, and the nip width can be easily adjusted by simply changing the position of the position adjustment roller, etc., without moving the developing device. Further, in the region of the photoreceptor corresponding to the non-document portion, the photoreceptor belt is separated from the developing sleeve to prevent unnecessary adhesion of toner and to reduce wear of the photoreceptor belt.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an embodiment of the present invention;
The figure is a sectional view showing another embodiment of the present invention, FIG.
FIG. 4 is a cross-sectional view of the vicinity of the embodiment shown in FIGS. 1 and 2, respectively, showing a state in which the position adjustment roller is replaced with a sliding member. DESCRIPTION OF SYMBOLS 1... Endless photoreceptor belt, 2, 3, 4... Belt support roller, 5... Position adjustment roller, 11... Developing sleeve, 15... Sliding member.

Claims (1)

[Claims for Utility Model Registration] (1) A latent image formed on an endless photoreceptor belt stretched around supporting members such as a plurality of rollers, etc., on the outer circumferential surface of the photoreceptor belt at a portion away from the rollers. In the endless photoreceptor belt support device of an electrophotographic apparatus, in which development is performed by contacting a rotatable developing sleeve at a fixed position of the apparatus main body, the inner periphery of the photoreceptor belt is attached at two positions near both sides of the developing sleeve contact position. a member that contacts the surface in a mutually movable manner, the member being supported at the ends of both arms of a bifurcated member movable in a direction perpendicular to the photoreceptor belt at a position facing the developing sleeve; The bifurcated member is movable by the two contacting members between a position where the photoreceptor belt is pressed against the developer sleeve and a position where the photoreceptor belt is separated from the developer sleeve, An endless photoreceptor belt support device characterized in that the position at which it is pressed against the developing sleeve is adjustable so that the nip width between the photoreceptor belt and the developing sleeve can be adjusted. (2) The above-mentioned bifurcated member is displaced to a position that brings the photoreceptor into contact with the developing sleeve during development and separates the photoreceptor from the developing sleeve during non-development. The endless photoreceptor belt support device according to item 1.