JPS61167968A - Electrophotographic copying machine - Google Patents

Abstract

PURPOSE:To attain size reduction and simplification by charging an image formation surface in the 1st turn and transferring a visible image formed on the image formation surface to transfer paper in the 2nd turn. CONSTITUTION:Corona ions having the opposite polarity of charges of toner are given to the reverse surface of transfer paper supplied from a paper feed cassette 9 at a transfer position by an electrostatic charging device 8 to charge the reverse surface electrostatically, and a toner image is transferred to the transfer paper 10. A beltlike photosensitive body from which the transfer paper 10 is separated enters the 2nd turn and reaches the installation position of an exposure device 3 again. At this time, its residual potential is held high because the use of a separating electrode, etc. is omitted. For the purpose, electrostatic discharging is performed by using the illumination lamp 3a of the exposure device 3. Thus, the copying process is completed in the two-turn process, so the copying machine is reduced in height and unnecessary space is removed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electrophotographic copying machine, and more particularly to an electrophotographic copying machine that is small and has a simplified mechanism.

(Prior Art) In general, electrophotographic copying machines have recently become particularly useful because they can continuously obtain clear copied images on plain paper.

However, with conventional equipment, the copying process involves charging, exposing, and
It consists of continuous processes such as development, transfer, cleaning, etc., and the space within the device to install each component required for each of these steps increases, making the device larger and the mechanism more complicated. Inspection, repair, adjustment, etc. of the equipment are often time-consuming, and failures are also likely to occur, resulting in a decrease in reliability.

From this point of view, for example, Japanese Patent Application Laid-Open No. 51-147327
As seen in the publication, in an attempt to further simplify the apparatus, the copying process was structured so that one copy was obtained in two rotations, and at the same time, a developing and cleaning device was developed that could perform both developing and cleaning functions in one device. Also known is an electronic copying apparatus that is equipped with a charging/transferring device that can perform both charging and transferring functions in one device.

FIG. 2 is a diagram showing a schematic configuration of an electrophotographic copying machine using a photoreceptor that completes the above-mentioned copying process in two revolutions. rvfi the summary.

In the figure, 4 is a drum-shaped photoreceptor that rotates in the direction of the arrow, η
1 is an exposure device including an optical system for exposing the original A23; In a photocopying machine, an image of a document B that is first exposed by an exposure device 5 is formed as an electrostatic latent image on a drum-shaped photoreceptor 21 that is charged by a charging transfer device δ. This electrostatic latent image is developed with toner in the magnetic brush device array and becomes a visible image, which is transferred to the drum photoreceptor 2.
As the image rotates in the direction of the arrow 1, it reaches the transfer position T, where it is transferred onto the transfer paper fed from the paper feeder 26 by the action of the charged transfer device 5, and then separated by the separation electrode n and transferred. , the transferred image is fixed by the fixing device section.

The toner remaining on the drum-shaped photoreceptor 21 without being transferred is
It moves as the drum-shaped photoreceptor 21 rotates for the second rotation, and after being neutralized by the action of the static eliminating lamp 4, the static electricity is removed by suction by the brushes of the magnetic brush device array, and the copying process is completed. Note that the above-mentioned static elimination can also be performed by changing the illumination optical path of the illumination lamp of the exposure device 4.

Such systems require the use of a photoreceptor with a surface area corresponding to the size of the image to be reproduced. For example A3
When copying an image on a plate, the size of the photoreceptor (in the case of a drum-shaped photoreceptor, the length of the outer circumference of the drum) must be at least larger than the A3 size.

Therefore, in the case of a drum-shaped photoreceptor, its diameter becomes very large, making it difficult to miniaturize the device. At the same time, with a drum-shaped photoreceptor having a large diameter, it is difficult to separate the transfer paper after transfer, and the usual separation means uses AC corona charging, but in the two-rotation copying process as described above, it is turned off ( It has drawbacks that should be improved, such as requiring complicated control such as turning it OFF and turning ON only the second rotation.

(Problems to be Solved by the Invention) From the above-mentioned viewpoints, the present invention is capable of downsizing a copying machine and employs a two-rotation copying process that uses a simplified process unit and does not require complicated control. The purpose is to provide electrophotographic copying machines.

(Means for Solving the Problems) According to the present invention, the above-mentioned problems of the present invention are solved by providing a belt-like image carrier that completes one copying process in two revolutions, and a belt-like image carrier that An exposure device provided therein, and an electrostatic latent image formed on the image forming surface of the image carrier in the first rotation are developed with toner to form a visible image, and the image is rotated twice A magnetic brush device for cleaning residual toner left on the photosensitive surface of the eye; and a magnetic brush device provided on the rotational side of the magnetic brush device, which charges the image forming surface in the first rotation and charges the image forming surface in the second rotation. This problem could be solved by using an electrophotographic copying machine equipped with a charging device that transfers the visible image formed on transfer paper onto transfer paper. The belt-like image bearing member used in the present invention refers to a member having a function of retaining an image-like charge on its surface after imparting a charge to its surface, and is, for example, a photoreceptor for electrophotography.

(Embodiments) Hereinafter, the electrophotographic copying machine of the present invention will be specifically described according to the embodiments shown in the drawings.

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

In the figure, reference numeral 1 denotes a belt photoreceptor which is an image carrier, and is a conductive support such as a thin metal plate or a plastic film on which a conductive thin layer is provided by vapor deposition sputter lamination. An inorganic photoconductor made of zinc, cadmium sulfide, amorphous silicon, etc. or a single layer or a laminated organic photoconductor consisting of a charge carrier generation layer and a charge carrier transport layer is coated or vapor-deposited as a photoreceptor.

The belt photoreceptor 1 is rotatably stretched around drive rollers 2a and 2b, and can therefore rotate in the direction of the arrow in the figure as the drive rollers 2a and 2b are driven.

Reference numeral 3 denotes an exposure device for projecting the image of the original 4 onto the belt photoreceptor. Further, reference numeral 5 is located on the side of the rotation direction from the exposure device 3, and functions as a magnetic brush developing device for developing the electrostatic latent image into a visible image with toner during the 101st rotation of the belt photoreceptor. This is a magnetic brush device that functions as a magnetic brush cleaner for removing toner from the belt photoreceptor 1.

The above-mentioned magnetic brush device 5 is mainly composed of a magnetic sleeve 5a that resists adhesion of the developer to form a magnetic brush, an agitator 5b that stirs the developer, and a bristled regulating plate 5C.

Since the charge polarity of the toner remaining without being transferred is not necessarily the same as the polarity at the time of development, the bias voltage of the magnetic sleeve 5a can be switched between the time of development and the time of cleaning. In the figure, 6 is a bias power supply that applies a bias voltage to the magnetic sleeve 5a via the protective resistor 7.

Reference numeral 8 is located further in the direction of rotation from the magnetic brush device 5, and applies corona charge to the photosensitive surface of the photoreceptor during the first rotation of the belt photoreceptor 1, and forms a corona charge on the belt photoreceptor 1 during the second rotation. This is a charging device that has the function of transferring a toner image to a transfer plate.

This charging device W8 has the 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 normally used discharge electrode, and also has the function of generating a corona charge by applying a high voltage to the corona wire as a discharge electrode, which is commonly used. A constant flow of corona ions with a polarity opposite to that of the toner on the belt photoreceptor 1 is poured onto the back of the paper, and the toner image on the belt photoreceptor 1 is transferred onto the transfer paper 10 by charging the paper to a polarity that attracts the toner. It has a function that can be used.

The copying process using the electrophotographic copying machine of the present invention configured as described above will be described as follows.

First, an image of the document 4 is projected by the exposure device W3 onto the belt photoreceptor 1 which has been given a corona charge by the charging device 8.
An electrostatic image is formed.

The electrostatic latent image formed on the belt photoreceptor 1 moves as the belt photoreceptor 1 rotates in the direction of the arrow, and the electrostatic latent image is moved by the magnetic brush device f.
At t5, magnetic brush development is performed using a developer that is a mixture of a carrier and a triboelectrically charged toner, or a magnetic one-component developer, and a toner image is visualized.

The above toner image moves further as the belt photoreceptor 10 rotates, and reaches the transfer position of the charging device 8.

At this transfer position, the charging device 8 charges the back surface of the transfer paper 10 fed from the paper feed cassette 9 with corona ions having a polarity opposite to that of the toner, and the toner on the belt photoreceptor 1 is charged. The image is transferred onto the transfer paper IO.

After being transferred as described above, the separated transfer paper 10 is conveyed for fixing and is heated and fixed by a pair of fixing rollers 11, so that a completed copy image is obtained on the transfer string 10.

On the other hand, the belt photoreceptor 1 from which the transfer paper 0 has been separated enters its second rotation and reaches the installation position of the exposure device 3 again. At this time, since the use of a separation electrode or the like is omitted in the belt photoreceptor 1 as described above, residual lightning is maintained at a considerably high level. Therefore, it is normally necessary to eliminate the static electricity using a static elimination lamp or the like, but the electrophotographic copying machine of the present invention has the advantage that the static electricity can be eliminated using the illumination lamp 3a of the exposure device f3.

That is, the illumination lamp 3a of the exposure apparatus 3 according to the present invention rotates, for example, the reflector of the lamp by 180 degrees around the lamp as shown by the dotted line in FIG. Static charge can also be removed by configuring the belt photoreceptor 1 so that the illumination light can directly irradiate the belt photoreceptor 1. Also, by moving a light shielding member provided in advance on the back side of the illumination lamp 3a, the illumination light can directly irradiate the belt photoreceptor 1. Even if it is configured so that it hits the body 1, static electricity can be eliminated.

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

The residual toner is cleaned by the magnetic brush device 5 by applying a bias voltage higher than that during development to the magnetic sleeve 5a.

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

Since the electrophotographic copying machine of the present invention uses a belt photoconductor as described above, it requires less wasted space compared to a drum-shaped photoconductor, and the height of the copying machine can be lowered. , there is also a large degree of freedom in the arrangement of process units. Furthermore, as mentioned above, there is also the advantage that the process is simplified and the number of parts can be reduced. Moreover, since the curvature at the transfer portion can be made larger than that of a drum, separation of the transfer paper is easy.

However, on the other hand, in the case of a belt photoreceptor, it is necessary to select the position for forming one image because there is a seam.
Another drawback is that blade cleaning cannot be performed because of the convex portion at the seam.

Regarding the above problem, since the electrophotographic copying machine of the present invention uses a two-rotation process, a photoreceptor for one screen is required, and the position of the head of the image can be determined in advance by detecting the seam with a detection member. If the control is carried out as follows, it should be possible to avoid the appearance of 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 cleaning is performed using a magnetic brush, cleaning can be performed regardless of the convex portion of the seam.

Furthermore, in the electrophotographic copying machine of the present invention, the belt photoreceptor and the magnetic brush device are integrated into a unit, since paper dust and the like may get mixed in with the magnetic brush for cleaning, which may have an adverse effect on development. Since it is constructed so that it can be easily replaced after a certain amount of copies have been made, it will not interfere with development.

Furthermore, since the charging device is also used for both charging and transfer, it is likely to get dirty, so it is preferable to integrate the charging device with the above-mentioned unit.

As mentioned above, in the present invention, it is possible to double the illumination lamp of the exposure device without providing a static elimination lamp.
There are a wide variety of optical systems for exposure equipment that can also be used as static elimination lamps, but for example, laser optical systems, LIDs, liquid crystal heads, and other optical systems that respond to electrical signals. If an exposure member capable of recording is used, it is convenient because the entire surface can be exposed and static electricity removed simply by sending a signal to turn on the entire surface.

(Effects of the Invention) The electrophotographic copying machine according to the present invention uses a belt-like image carrier to complete the copying process by a two-rotation process, thereby reducing the height of the copying machine and eliminating wasted space. This method has the advantage that it has a large degree of freedom in arranging the process units, and that the number of parts can be reduced.

[Brief explanation 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.

Claims (3)

[Claims] (1) A belt-like image carrier that completes one copying process in two revolutions, an exposure device provided facing the belt-like image carrier, and a a magnetic brush device that develops an electrostatic latent image formed on the image forming surface of the image bearing member during the first rotation with toner to form a visible image, and also cleans residual toner left on the image forming surface during the second rotation; Provided on the rotation direction side from this magnetic brush device,
An electrophotographic copying machine comprising a charging device that charges the image forming surface during the first rotation and transfers the visible image formed on the image forming surface onto transfer paper during the second rotation. (2) The electrophotographic copying machine according to claim 1, wherein the belt-like image carrier and the magnetic brush device are integrated as a unit and are detachable. (3) The electrophotographic copying machine according to claim 1, wherein the exposure device is a device that also serves as a static elimination lamp.