JPH0363755B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developing device in an electronic copying machine.

[Prior art]

Some electronic copying machines use a belt-shaped photoreceptor to create a copy image through charging, exposure, development, transfer, and fixing steps.

FIG. 1 shows an example of such a conventional electronic copying machine.

In this electronic copying machine, a belt-shaped photoreceptor 4 is wound around a driving roller 1 and two driven rollers 2 and 3. When the driving roller 1 rotates and the photoreceptor 4 travels in the direction of arrow A, the surface of the photoreceptor 4 is first charged by the charger 5 . When the charged surface of the photoreceptor 4 passes a predetermined position, an exposure device (not shown) performs image exposure as shown by arrow B.
An electrostatic latent image is formed on the surface of the photoreceptor 4. The electrostatic latent image is developed with toner particles at a location facing the developing device 6, forming a toner image.

On the other hand, paper 7 sent out from a paper cassette (not shown) is transported as indicated by arrow C by a transport device (also not shown), and is superimposed on the toner image formed on photoreceptor 4. The toner image on the photoreceptor 4 is transferred onto the stacked sheets 7 by the action of the transfer device 8 . The transferred paper 7 is peeled off from the photoreceptor 4 by the action of the static eliminator 9, sent to a fixing device (not shown), fixed thereon, and then discharged to a discharge tray (also not shown). The toner image remaining on the surface of the photoreceptor 4 is neutralized by a static eliminator 10 and then cleaned by a cleaning device 11.

2 and 3 show a part of the developing device 6 of this electronic copying machine.

This developing device 6 performs development by a magnetic brush developing method. In such a developing method, it is necessary to maintain a constant distance between the developing roll 21 for forming a magnetic brush and the photoreceptor 4. For this reason, this developing device 6 is designed with such a design.

The main body 22 of the developing device 6 is provided on the surface side of the photoreceptor 4. A support plate 23 is attached to the developing device main body 22 with screws 24 . A developing roll 21 is rotatably supported on the support plate 23 via a bearing 25 . A protrusion 26 is formed at a predetermined location corresponding to the developing roll 21 at the upper end of the support plate 22 . A position regulating roller 27 is provided at a predetermined location facing the developing roll 21 on the back side of the photoreceptor 4 . The position regulating roller 27 has a bearing 28
It is rotatably supported by a support plate 29 via. A portion of the bearing 28 protrudes below the support plate 29. The support plate 29 is attached via a pin 30 to a long hole 32 formed in the side plate 31 so as to be vertically movable. The support plate 29 is urged downward by the force of the spring 33, and is positioned at a position where the bearing 28 comes into contact with the protrusion 26 of the support plate 22. As a result, the position regulating roller 27 is brought into pressure contact with the back surface of the photoreceptor 4, and the distance between the photoreceptor 4 and the developing roll 21 is kept constant.

By the way, in such a developing device, the position regulating roller 27 is positioned by simply bringing the bearing 28 into contact with the protrusion 26. Therefore, in such a developing device, the position regulating roller 2 is
The position of 7 will be affected. If the position regulating roller 27 is misaligned, the distance between the photoreceptor 4 and the developing roll 21 will change, and the relative angle of the photoreceptor 4 to the developing roll 21 will also change, which will adversely affect image quality. For this reason, such a conventional developing device requires high precision in the dimensions and assembly positions of each component, which has been an obstacle in efforts to reduce costs.

Further, some of such developing devices use a plurality of developing rolls 21 in order to improve the developing efficiency and increase the copying speed. In such a developing device, the number of protrusions 26 corresponding to the number of developing rolls 21 is provided, and the number of position regulating rollers 27 corresponding to the number of protrusions 26 is provided. Therefore, in such a developing device, as the number of developing rolls 21 increases, the weight increases, the load on the photoreceptor traveling system increases, and the cost also increases.

Another conventional electronic copying machine uses a position regulating plate 35 instead of a position regulating roller, as shown in FIG. However, in such an electronic copying machine, the photoreceptor 4 is located on the position regulating plate 35.
As a result, the load on the photoreceptor traveling system increases, and the photoreceptor 4 is likely to wear out, shortening its lifespan.

[Purpose of the invention]

The present invention has been made in view of the above problems, and has an object to always reliably position a position regulating roller for regulating the position of a belt-shaped photoreceptor at a desired position, and to increase the number of developing rolls. An object of the present invention is to provide a developing device that can reduce the number of position regulating rollers by half when the number of rollers increases, thereby reducing weight and cost.

[Structure of the invention]

The present invention is an electronic copying machine that uses a belt-shaped photoreceptor, develops an electrostatic latent image formed on the surface with toner particles, and transfers the resulting toner image onto paper to create a copy image. , a plurality of developing rolls rotatably provided on the surface side of the photoconductor for supplying toner particles to the surface by a magnetic brush development method, and a support member rotatably supporting these developing rolls. , is rotatably provided on the back side of the mold facing an intermediate position between two of the plurality of developing rolls, and comes into contact with the back side to regulate the position of the photoreceptor with respect to the two developing rolls. A position regulating roller is provided symmetrically at a position corresponding to an intermediate position between the two developing rolls of the supporting member, and comes into contact with a shaft portion of the position regulating roller to regulate the position of the position regulating roller. It is equipped with a pair of rollers.

With this configuration, the position regulating roller is always reliably positioned at a position corresponding to the middle of the two rollers, and as a result, the intervals between the belt-shaped photoreceptor and the two developing rolls are constant, and the distance between the photoreceptor and the two developing rolls is constant. The angle with respect to each developing roll is constant, and image quality is not adversely affected. Further, each interval between the photoreceptor and the two developing rolls can be maintained constant by one position regulating roller, and even if the number of developing rolls increases, the number of position regulating rollers may be about half of that number. Weight and cost increases can be reduced.

〔Example〕

The present invention will be explained in detail with reference to Examples below.

5 and 6 show the main parts of a developing device in an embodiment of the present invention. In these figures, parts having the same names as those in FIGS. 2 and 3 are given the same reference numerals, and their explanations will be omitted as appropriate.

In this developing device, another support plate 41 is attached to the upper part of the support plate 23 at a predetermined location corresponding to the middle between the two developing rolls 21 with screws 42 . The upper part of the support plate 41 projects above the support plate 23. A pair of shafts 43 are symmetrically provided on the upper part of the support plate 41. Rollers 44 are fitted onto these shafts 43, respectively. Bearings 28 provided on the position regulating rollers 27 are mounted on these rollers 44 . Although not shown, the support plate 29 supporting the bearing 28 is attached via a pin to a long hole in the side plate so as to be vertically movable, and is biased downward by the force of a spring. has been done.

Therefore, in this developing device, the bearing 28 is evenly pressed against the pair of rollers 44 by the force of the spring.
It will always be reliably positioned at a position corresponding to the middle of these rollers 44. A pair of rollers 44
are arranged symmetrically at a location corresponding to the middle of the two developing rolls 21, so the position regulating roller 2
7 and the two developing rolls 21 are the same. For this reason, the photoconductor 4 and the two developing rolls 2
The intervals between both are also the same. As a result, the distances between the photoreceptor 4 and the two developing rolls 21 are kept constant.

In this developing device, one position regulating roller 27 is used for two developing rolls 21, and the photoreceptor 4
and the two developing rolls 21 are kept constant. Therefore, even if the number of developing rolls 21 increases, the number of position regulating rollers 27 may be about half that number. Therefore, even if the number of developing rolls 21 increases, the increase in weight is reduced, the load on the photoreceptor traveling system is also reduced, and furthermore, the increase in cost is also reduced.

In the above embodiment, the position regulating roller 27 is placed on the pair of rollers 44 via the bearing 28, but the pair of rollers 44 is made rotatable without using the bearing 28, and the position regulating roller 27 is placed on the pair of rollers 44 via the bearing 28. The shaft of the regulating roller 27 may be placed directly on these rollers 44.

〔Effect of the invention〕

As described above, according to the developing device of the present invention, the position of the position regulating roller that regulates the position of the belt-shaped photoreceptor relative to the two developing rolls is supported by a pair of rollers provided at predetermined positions. Therefore, the position regulating roller can always be reliably positioned at a position corresponding to the middle of the two rollers, and the intervals between the belt-shaped photoreceptor and the two developing rolls are both constant. Therefore, even if there are some errors in the dimensional accuracy and assembly position of each component that makes up the developing device,
Development can be performed satisfactorily. Furthermore, since the distance between the photoreceptor and the two developing rolls can be maintained constant by one position regulating roller, even if the number of developing rolls increases, the number of position regulating rollers can be reduced to half. Increases in weight and cost can be reduced, and therefore an electronic copying machine with improved development efficiency can be manufactured at low cost.

[Brief explanation of drawings]

Fig. 1 is a schematic front view showing an example of a conventional electronic copying machine, Fig. 2 is a front view showing a part of the developing device of the same copying machine, and Fig. 3 is a longitudinal cross-sectional side view taken along the - line in Fig. 2. , FIG. 4 is a schematic front view showing a part of another conventional electronic copying machine, FIG. 5 is a front view showing main parts of a developing device in an embodiment of the present invention, and FIG. - is a longitudinal cross-sectional side view along the line. 4... Belt-shaped photoreceptor, 6... Developing device, 2
1...Developing roll, 23...Support plate, 27
...Position regulating roller, 29...Support plate, 4
1...Support plate, 44...Colo.

Claims (1)

[Claims] 1. Using a belt-shaped photoreceptor, an electrostatic latent image formed on the surface is developed with toner particles, and the resulting toner image is transferred onto paper to create a copy image. In an electronic copying machine, a plurality of developing rolls are rotatably provided on the surface side of a photoreceptor and for supplying toner particles to the surface by a magnetic brush development method, and these developing rolls are rotatably supported. a support member, which is rotatably provided on the back surface side of the photoconductor facing an intermediate position between two of the plurality of development rolls, and is in contact with the back surface of the photoconductor to support the photoconductor relative to the two development rolls; a position regulating roller that regulates the position; and a position regulating roller that is symmetrically provided at a position corresponding to an intermediate position between the two developing rolls of the supporting member, and that is in contact with a shaft portion of the position regulating roller so as to control the position of the position regulating roller. A developing device characterized by comprising a pair of rollers that regulate the position.