JPH0623914B2 - Electrophotographic copier - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic copying machine, and more particularly to a small-sized electrophotographic copying machine having a simplified mechanism.

(Prior Art) Generally, an electrophotographic copying machine has recently been particularly useful because it can continuously obtain a clear copy image on plain paper.

However, in the conventional apparatus, the copying process involves charging, exposing,
It consists of continuous processes such as development, transfer, cleaning, etc., which increases the space in the device for mounting each component required for each process, increasing the size of the device and complicating the mechanism. In many cases, it is time-consuming to perform inspections, inspections, repairs, adjustments, and the like of equipment, and failures are likely to occur, which causes a decrease in reliability.

From such a point of view, in an attempt to further simplify the apparatus as disclosed in Japanese Patent Laid-Open No. 51-147327, for example, the copying process is configured to obtain one copy by two rotations, and the developing process is performed at the same time. There is also known an electronic copying apparatus equipped with a developing / cleaning combined device capable of performing a cleaning function and a cleaning function in one device, and a charging / transferring combined device capable of performing charging and transfer functions in a single device.

FIG. 2 is a diagram showing a schematic structure of an electrophotographic copying machine using a photoconductor that completes the copying process as described above in two rotations. The electrophotographic copying machine completes the copying process in two rotations according to the above drawing. The process is outlined below.

In the figure, 21 is a drum-shaped photoconductor that rotates in the direction of the arrow, 22
Is an exposure device including an optical system for exposing the original 23, 24 is a magnetic brush device for both development and cleaning, and 25 is a charging transfer device for both charging and transfer.

In the electrophotographic copying machine configured as described above, the image of the original document 23 previously exposed by the exposure device 22 is formed as an electrostatic latent image on the drum-shaped photoconductor 21 charged by the charging transfer device 25. It This electrostatic latent image is toner-developed in the magnetic brush device 24 to become a visible image, reaches the transfer position T as the drum photoconductor 21 rotates in the arrow direction, and is charged on the transfer paper supplied from the paper feed cassette 26. The transferred image is transferred by the operation of the transfer device 25, then separated and transferred by the separation electrode 27, and the transferred image is fixed by the fixing device 28.

The toner remaining on the drum-shaped photoconductor 21 without being transferred is 2
The drum-shaped photosensitive member 21 of the second rotation moves, the charge is removed by the action of the charge removal lamp 29, and then the brush of the magnetic brush device 24 sucks and removes it to complete the copying process. Note that the above static elimination can also be performed by changing the illumination optical path of the illumination lamp of the exposure device 22.

Such a method requires the use of a photoreceptor having an area corresponding to the size of the image to be copied. For example, A3
When copying an image on a plate, the size of the photosensitive member (in the case of a drum-shaped photosensitive member, the outer peripheral length of the drum) must be at least larger than that of the A3 plate.

Therefore, in the case of a drum-shaped photoreceptor, its diameter becomes very large, and it becomes difficult to downsize the device. At the same time, it is difficult to separate the transfer paper after transfer with a drum-shaped photoconductor having a large diameter, and AC corona charging is used in the normal separating means. OFF), and has a drawback to be improved such as requiring complicated control such that only the second rotation is turned on.

(Problems to be Solved by the Invention) From the above viewpoints, the present invention is based on a two-rotation copying process that can downsize a copying machine and that does not require complicated control with a simplified process unit. The purpose is to provide an electrophotographic copying machine.

(Means for Solving the Problems) According to the present invention, the above-described object of the present invention is one of a belt-shaped image carrier that is stretched between two drive rollers and that rotates with the drive of the drive rollers. A charging device having a function of uniformly charging the image carrier or transferring a toner image onto a transfer paper, which is opposed to the belt-shaped image carrier on the driving roller, and performs image exposure on the downstream side thereof. An exposure device is provided, and a magnetic brush device having a function as a developing or cleaner by a magnetic brush is provided facing the belt-shaped image carrier on the other driving roller, and the first rotation of the belt-shaped image carrier is provided. In the second rotation of the belt-shaped image carrier, the image carrier is uniformly charged by the charging device, the latent image is formed by the exposure device, and the toner image is formed by the development of the magnetic brush device. , The toner image on the image carrier is supplied from below by the charging device. After the transfer is performed on the transfer paper, the exposure device removes the electricity, and the cleaning is performed by the magnetic brush device.The belt-shaped image carrier and the magnetic brush device are integrated as a unit and detachable. I was able to solve the problem with the electrophotographic copying machine. The belt-shaped image carrier referred to in the present invention means one having a function of retaining an image-like electric charge on the surface after applying the electric charge to the surface, and is, for example, an electrophotographic photoreceptor.

(Embodiment) An electrophotographic copying machine of the present invention will be specifically described below with reference to an embodiment of the drawings.

FIG. 1 is a diagram showing a schematic configuration of an electrophotographic copying machine of the present invention.

In the figure, reference numeral 1 is a belt photosensitive member which is an image bearing member, for example, selenium or an oxide on a conductive support such as a metal thin plate or a film in which a conductive thin layer is provided on a plastic film by vapor deposition sputter lamination or the like. An inorganic or single layer of zinc, cadmium sulfide, amorphous silicon or the like, or a laminated organic photoconductor comprising a charge carrier generating layer and a charge carrier transporting layer is applied or vapor-deposited as a photoreceptor.

The belt photosensitive member 1 is rotatably stretched around the driving rollers 2a and 2b, and therefore can be rotated in the direction of the arrow in the drawing as the driving rollers 2a and 2b are driven.

Reference numeral 3 denotes an exposure device for projecting the image of the original 4 on the belt photoconductor. Further, 5 is on the rotation direction side from the exposure device 3, and functions as a magnetic brush developing device for developing the electrostatic latent image into a visible image by toner development at the first rotation of the belt photosensitive member 1, and at the second rotation. Is a magnetic brush device that functions as a magnetic brush cleaner for removing the residual toner from the belt photoreceptor 1.

The above magnetic brush device 5 is mainly configured by a magnetic sleeve 5a for attaching a developer to form a magnetic brush, an agitator 5b for agitating the developer, and a spike control plate 5c.

The charge polarity of the toner remaining without being transferred is not necessarily the same as the polarity when the toner is developed, so that the bias voltage of the magnetic sleeve 5a can be switched between the time of development and the time of cleaning. Reference numeral 6 in the drawing denotes a bias power source for applying a bias voltage to the magnetic sleeve 5a via the protection resistor 7.

Reference numeral 8 is further on the rotational direction side from the magnetic brush device 5. Corona charging is applied to the photosensitive surface of the photosensitive drum at the first rotation of the belt photosensitive member 1, and on the belt photosensitive member 1 at the second rotation. The charging device has a function of transferring the formed toner image onto a transfer sheet. The charging device 8 has a function of generating a corona charge by applying a high voltage from a high-voltage power source (not shown) to a corona wire as a discharge electrode which is usually used, and further, from the corona wire, the back surface of the transfer paper. A function capable of transferring a toner image on the belt photoconductor 1 onto the transfer paper 10 by pouring a constant corona ion flow having a polarity opposite to that of the charging of the toner on the belt photoconductor 1 to the toner so that the toner is attracted and charged. Is to have.

The copying process by the electrophotographic copying machine of the present invention having the above structure will be described below.

The image of the original 4 is projected by the exposure device 3 onto the belt photosensitive member 1 to which the corona charge is applied by the charging device 8 in advance.
An electrostatic image is formed.

The electrostatic latent image formed on the belt photosensitive member 1 moves along with the rotation of the belt photosensitive member 1 in the direction of the arrow, reaches the magnetic brush device 5, and is a mixture of the carrier and the triboelectrically charged toner. The toner image is visualized as a toner image by magnetic brush development using a certain developer or a magnetic one-component developer.

The toner image further moves as the belt photosensitive member 1 rotates, and reaches the transfer position of the charging device 8. At the transfer position, the sheet feeding cassette 9 is charged by the charging device 8 described above.
Corona ions having a polarity opposite to that of the toner are applied to the back surface of the transfer paper 10 fed from the above to charge the transfer paper 10, and the toner image on the belt photoconductor 1 is transferred onto the transfer paper 10.

After being transferred as described above, the separated transfer paper 10 is conveyed for fixing and heated and fixed by a pair of fixing rollers 11 to obtain a completed copying machine on the transfer paper 10.

On the other hand, the belt photosensitive member 1 from which the transfer paper 10 has been separated enters the second rotation and reaches the installation position of the exposure device 3 again. At this time, since the use of the separating electrodes and the like is omitted in the belt photosensitive member 1 as described above, the residual potential is kept fairly high. Therefore, it is usually necessary to remove the charge by using a charge removing lamp or the like, but the electrophotographic copying machine of the present invention has an advantage that the charge can be removed using the illumination lamp 3a of the exposure device 3.

That is, the illumination lamp 3a of the exposure apparatus 3 according to the present invention
When the belt photosensitive member 1 is started to rotate for the second time, static electricity is removed by, for example, rotating the reflector of the lamp by 180 ° around the lamp so that the illuminating light can directly irradiate the belt photosensitive member 1. It is also possible to remove the charge by moving the light blocking member provided in advance on the back surface of the illumination lamp 3a so that the illumination light strikes the belt photosensitive member 1.

The belt photoconductor 1 whose charge has been removed as described above continues to rotate for the second rotation, and the toner remaining on the belt photoconductor 1 is cleaned and removed by the magnetic brush device 5.

Cleaning of residual toner by the magnetic brush device 5 is performed by applying a bias voltage higher than that at the time of development to the magnetic sleeve 5a.

In the apparatus of the present invention, one copying process is completed when the residual toner on the belt photosensitive member 1 is swept and removed by the magnetic brush of the magnetic sleeve 5a.

Since the electrophotographic copying machine of the present invention uses the belt photosensitive member as described above, the wasteful space is smaller than that of the drum-shaped photosensitive member, and the height of the copying machine can be reduced. The degree of freedom in arranging process units is also great. Further, as described above, there is an advantage that the process is simplified and the number of parts is small. Moreover, since the curvature at the transfer portion can be made larger than that of the drum, the transfer paper can be easily separated.

However, on the other hand, in the case of a belt photoreceptor, there is a seam, so it is necessary to select the position of image formation,
Further, there is a drawback that the blade cleaning cannot be performed because the joint has a convex portion.

With respect to the above-mentioned problems, the electrophotographic copying machine of the present invention requires a photosensitive member for one screen because it is a two-rotation process, and the position of the head of the image is detected in advance by detecting the seam by the detection member. If it is controlled to, it should be possible to avoid a seam in the middle of the image, and it is possible to eliminate it.

Further, in the electrophotographic copying machine of the present invention, since the cleaning is carried out by the magnetic brush, the cleaning can be carried out regardless of the convex portion of the joint.

Furthermore, in the electrophotographic copying machine of the present invention, since cleaning is performed with a magnetic brush, there is a possibility that paper dust or the like may be mixed in and adversely affect development. Therefore, the belt photosensitive member and the magnetic brush device are integrally formed as a unit. Since it is configured to be easily replaced after a certain amount of copying is completed, it does not hinder the development.

Furthermore, since the charging device is used for both charging and transfer, it is liable to be contaminated. Therefore, it is preferable to integrate it with the above unit.

As described above, in the present invention, it is possible to serve as the illumination lamp of the exposure apparatus without providing the static elimination lamp.
As the optical system of the exposure apparatus which can also be used as such a discharge lamp, various optical systems can be widely mentioned. For example, a laser optical system, an LED, a liquid crystal head, etc. It is convenient to use an exposure member capable of recording, because the entire surface can be exposed and the charge can be removed simply by sending a signal for lighting the entire surface.

(Effects of the Invention) The electrophotographic copying machine according to the present invention has a structure in which the belt-shaped image carrier can be used to complete the copying process by a two-rotation process. Therefore, the height of the copying machine is reduced and unnecessary space is saved. This has the advantages that the process unit can be arranged with a high degree of freedom, and the number of parts can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of an electrophotographic copying machine of the present invention,
Further, FIG. 2 is a diagram showing a schematic configuration of a conventionally known electrophotographic copying machine. 1 ... Belt photoconductor, 3 ... Exposure device 4 ... Original document, 5 ... Magnetic brush device 8 ... Charging device, 10 ... Transfer paper

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location G03G 21/00 302 (56) References JP-A-58-7672 (JP, A) JP-A-58 -194077 (JP, A) JP-A-57-163277 (JP, A) Actually opened 58-31564 (JP, U) Actually opened 58-34148 (JP, U) Actually opened 58-36760 (JP, U) ) Actual development Sho 58-52562 (JP, U)

Claims (1)

[Claims] 1. One drive roller (2a) of a belt-shaped image carrier (1) which is stretched around two drive rollers (2a, 2b) and which rotates with the drive of the drive rollers (2a, 2b). ) Belt-shaped image carrier (1)
A charging device (8) having a function of uniformly charging the image carrier or transferring a toner image onto a transfer paper is provided opposite to, and an exposure device (3) for performing image exposure is provided downstream thereof. , Belt-shaped image carrier (1) on the other drive roller (2b)
A magnetic brush device (5) having a function as a developing device or a cleaner by a magnetic brush is provided opposite to the surface of the image carrier (1) at the first rotation of the belt-shaped image carrier (1). The charging device (8) uniformly charges the latent image on the belt, the exposure device (3) forms a latent image, and the magnetic brush device (5) develops a toner image to form a toner image on the belt-shaped image carrier (1). In the second rotation, the toner image on the image carrier (1) is transferred onto the transfer paper (10) fed from below by the charging device (8), and the exposure device (3)
Then, the magnetic brush device (5) is used for cleaning, and then the belt-shaped image carrier (1) and the magnetic brush device (5) are integrated as a unit to be removable. An electrophotographic copying machine characterized by that.