JPS60230672A - Image forming device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an image forming apparatus that serves both as a developing device and a cleaning device.

[Prior art and its problems]

A device has been proposed that functions as both a developing device and a cleaning device, and which performs both developing and cleaning at the same time.
FIG. 1 is a schematic configuration diagram of such an image forming apparatus.

A charging device 2 is installed around the photoreceptor 1. n-light device 3. Developing and cleaning device 4. Transfer device5. Eraser lamps 6 are arranged, and image formation is performed sequentially as the photoreceptor 1 rotates, but the circumference of the photoreceptor l is shorter than the size of the transfer paper 7 used, and even after the photoreceptor 1 has rotated once, Note that the formation of the first image continues. In other words, a new electrostatic latent image is formed over the residual toner image remaining on the photoreceptor 1 after the image formed during the first rotation of the photoreceptor 1 is transferred. Next, in the developing/cleaning device 4, this electrostatic latent image is developed and the residual toner on the photoreceptor 1 is also cleaned at the same time. In this way, image formation over one or more rotations of the photoreceptor 1 is completed.

By the way, in an image forming apparatus that serves both as a developing device and a cleaning device, there are two cleaning methods for cleaning the toner remaining on the photoreceptor after the transfer process is completed. A method is carried out by applying a bias to the electrostatic adsorption force between the charge of the toner and a magnetic brush, a method is carried out by the magnetic force of a one-component magnetic toner having magnetism as a developer, or a method is carried out by combining the above methods and using a magnetic carrier. A method using magnetic toner and its electrostatic adsorption force and magnetic force has been proposed.

This proposed cleaning method is sufficiently effective in the so-called conventional two-rotation, one-copy type apparatus in which the developing device and the cleaning device are combined, or in which developing and cleaning are not performed simultaneously. However, when the above-mentioned developing device and cleaning device are used together, and the developing and cleaning are performed simultaneously, sufficient cleaning performance cannot be obtained, and the residual toner image of the first rotation of the photoreceptor 1 remains uncleaned. This overlaps with a new image from the second rotation of the photoreceptor 1, resulting in a defective image.

[Purpose of the invention]

SUMMARY OF THE INVENTION In view of the above-mentioned drawbacks of the conventional image forming apparatus, it is an object of the present invention to provide an image forming apparatus which uses both a developing device and a cleaning device and has significantly improved cleaning ability, particularly in a system that performs simultaneous development and cleaning.

[Key points of the invention]

In order to achieve the above object, the present invention provides an image forming apparatus that serves both as a developing device for developing an electrostatic latent image on an image carrier with toner and as a cleaning device for cleaning untransferred toner on the image carrier. It is characterized in that the frictional charging polarity of the toner is made the same as the polarity of the electrostatic latent image.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a block diagram of an image forming apparatus showing an embodiment of the present invention.

The photoreceptor 8 is rotatably provided in the direction of the arrow shown in the figure, and a charging device 9 is provided around the photoreceptor 8. Exposure device 10, toner disturbance member 11. Developing and cleaning device 12. Transfer device 1
3. Eraser lamps 14 are sequentially arranged, and paper feed devices 15. Standby device 16, separation device 17. Fixing devices 18 are respectively arranged at predetermined positions.

The photoreceptor 8 has a circumference shorter than the size of the transfer paper used.

The toner agitating member 11 is a bristle brush that slides and rotates against the photoreceptor 8 .

Further, the developing/cleaning device 12 has a non-magnetic sleeve 12a rotatably provided around the outer periphery of a fixed magnet roll, and a magnetic brush is formed on the outer periphery of the sleeve 12a by magnetic carrier and magnetic toner. has been done. This magnetic toner has a characteristic of being charged to the same polarity as the electrostatic latent image formed on the photoreceptor 8 by frictional charging with the magnetic carrier.

Next, the operation of the image forming apparatus having the above configuration will be explained.

When the original is inserted from the six directions indicated by the arrows at the top of the main body, it is conveyed onto the original glass 19. The original transported onto the original glass 19 is irradiated with light by the exposure device 10, and the reflected light is projected onto the photoreceptor 8 via a lens and a mirror. The photoreceptor 8 is uniformly charged in advance to a predetermined polarity by a charging device 9, and an electrostatic latent image corresponding to the original is formed on the photoreceptor 8 by exposure. This formed photoreceptor 8
The upper electrostatic latent image then comes into contact with the toner-disturbing member 11 as the photoreceptor 8 rotates, but at this time, the toner-disturbing member 11 is in a non-operating state and is only rotating as a result of the photoreceptor 8. Therefore, the electrostatic latent image on the photoreceptor 8 is not disturbed. After passing through the rubbing part with the toner disturbing member 11, the photoreceptor 8
The upper electrostatic latent image is visualized with magnetic toner in a developing/cleaning device ff112. As mentioned above, the magnetic toner has a triboelectric charge with the same polarity as the charge polarity of the electrostatic latent image, but in the two image areas, the electrostatic induction is stronger than the electrostatic repulsion that acts between the electrostatic latent image and the magnetic toner. Alternatively, the electrostatic attraction force generated by dielectric polarization increases, and magnetic toner adheres to the image area of the electrostatic latent image. On the other hand, in the non-image area, no magnetic toner adheres at all due to the slight residual potential on the photoreceptor after exposure, the electrostatic repulsion of the magnetic toner, and the magnetic attraction between the magnetic carrier and the magnetic toner.

Here, the magnetic carrier not only imparts a predetermined charge to the magnetic toner, but also serves as a counter electrode for the electrostatic latent image and assists in electrostatic induction or dielectric polarization.

The developed image formed on the photoreceptor 8 in the developing process is then transferred to the photoreceptor 8.
The image is sent to the transfer area according to the rotation of the image. On the other hand, paper feeding device 15
The transfer paper fed from the direction of arrow B is transferred to the standby device 16.
It is once stopped at , and is fed again to the transfer area in synchronization with the developed image on the photoreceptor 8 . In the transfer area, a transfer device 13 transfers the developed image on the photoconductor 8 onto a transfer paper, and a separation device 17 separates the transfer paper from the photoconductor 8 and conveys it to the next fixing device 18 where it is fixed.

On the other hand, the photoreceptor 8 is optically neutralized by an eraser lamp 14 after the transfer process is completed.

In the known two-rotation, one-copy, one-copy system, a cleaning process is next performed, but in this second embodiment, since the circumference of the photoreceptor 8 is shorter than the size of the transfer paper, the image forming operation for the first sheet is continued.

The photoreceptor 8 that has passed through the eraser lamp 14 is charged again in a charging device 9. Magnetic toner was originally produced using photoreceptor 8.
Since the magnetic toner remaining on the photoconductor 8 is easily charged to the same polarity as the photoconductor 8 by passing through the charging device 9, the charge of the opposite polarity to the photoconductor 8 generated by electrostatic induction or dielectric polarization disappears, and the magnetic toner remaining on the photoconductor 8 disappears. charged to the same polarity as.

The uniformly charged photoconductor 8 enters the exposure process and is exposed to the exposure device 1.
0, a new electrostatic latent image is formed again.

The residual toner is uniformly disturbed by a toner disturbance member 11 that slides and rotates against the photoreceptor 8 at a predetermined rotational speed.

Subsequently, the electrostatic latent image is developed in the developing/cleaning device 12. At the same time as the electrostatic latent image is developed, the photoreceptor 8
The magnetic toner remaining on the sleeve 12a is easily collected by the magnetic brush due to the attraction force due to the magnetic force of the magnetic brush on the sleeve 12a and the electrostatic repulsion force due to the charges of the photoreceptor 8 and the magnetic toner. The new developed image formed during the second rotation of the photoreceptor 8 is then transferred onto a transfer paper in a transfer process, and the image forming process that spans one or more rotations of the photoreceptor 8 is completed. Next, the photoreceptor 8 enters a dedicated cleaning process and the image forming operation ends.

Next, a specific example will be further explained. A selenium photoreceptor was used as the photoreceptor 8, and when it was charged and exposed, the potential of the image area after exposure was +5oov and the potential of the non-image area was +80V.The developer was 50% by weight of magnetic carrier and magnetic toner (
A mixture of 50% and 50% by weight of magnetic material was used, and various magnetic toners having different amounts of triboelectric charge were used. The rotation speed of the sleeve 12a was 300 cuts/sec while the rotation speed of the photoreceptor 8 was 50 m/sec. The magnetic force on the sleeve 12a was about 700 Gauss.

The results of image formation under the above conditions are shown in Table 1 on the next page.
I got the result.

As can be seen from the results shown in Table 1, toner with a high amount of triboelectric charge has a low image density, and when toner that is triboelectrically charged to the opposite polarity to the electrostatic latent image on the photoreceptor 8 is used, non-image areas is dirty, and cleaning performance is poor, making it impossible to obtain satisfactory images.

Table 1 The magnetic toner used in the present invention has the property of being charged to the same polarity as the electrostatic latent image on the photoreceptor due to frictional charging with a magnetic carrier, and furthermore, the amount of frictional charging of the magnetic toner is It is desirable to use a material that does not excessively inhibit the adsorption force to the photoreceptor caused by induction or dielectric polarization.

〔Effect of the invention〕

As described above in detail, the image forming apparatus of the present invention has a significantly improved cleaning ability, and the effect is particularly great in an apparatus that serves both as a developing device and a cleaning device and performs cleaning at the same time as development.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional image forming apparatus, and FIG. 2 is a block diagram of an image forming apparatus showing an embodiment of the present invention. 8... Photoreceptor, 9... Charging device. 10... Exposure device, 11... Toner disturbance member,
12... Developing and cleaning device, 13... Transfer device, 14... Eraser lamp, 18... Fixing device patent Applicant Casio Computer Co., Ltd. Same as above ID Co., Ltd. Representative Patent Attorney Yoshi Osuga 2 Figure 1 10 +9 lil/ +5 16

Claims (1)

[Claims] In an image forming apparatus that serves both as a developing device that develops an electrostatic latent image on an image carrier with toner and a cleaning device that cleans untransferred toner on the image carrier, the frictional charging polarity of the toner is adjusted to An image forming apparatus characterized in that the polarity is the same as that of an image.