JP2600505B2 - Cleanerless image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleanerless image forming apparatus provided in a laser printer, a copying machine, or the like using an electrophotographic system.

[0002]

2. Description of the Related Art In general, in an image forming apparatus using an electrophotographic system, after recording information is exposed on a photosensitive drum to form an electrostatic latent image, toner is supplied to the latent image to supply a visible image (toner). Image), and the toner image is transferred to a sheet by a transfer unit provided opposite to the photosensitive drum, and then fixed to obtain one copy.

On the other hand, it is necessary to remove the untransferred toner remaining on the surface of the photosensitive drum from which the transfer of the toner image has been completed, and then proceed to the next image forming operation. Otherwise, the next image formation is performed while the residual toner image (usually called a memory) formed by the untransferred toner is left on the photosensitive drum, and the image quality is significantly deteriorated. become.

[0004] To remove the untransferred toner,
The toner is scraped off from the surface of the photosensitive drum by a scraping blade, the scraped toner is scooped from below by a scooping sheet, and is collected by a cleaner that collects the toner in a collection chamber. On the other hand, in the case of a cleaner-less image forming apparatus that does not use a cleaner, the untransferred toner is collected using electrostatic attraction in a developing unit that supplies toner to the electrostatic latent image on the photosensitive drum. Have been done. When such a recovery method is employed, the recovery efficiency of the untransferred toner is inevitably lower than when the toner is mechanically scraped off using a cleaner.

If the collection of untransferred toner is insufficient, the surface of the photosensitive drum is in a state where the memory is not completely removed. For this reason, the memory for dispersing the toner is removed by bringing the memory removing brush into contact with the surface of the photosensitive drum on which the transfer of the toner image has been completed. Then, the toner from which the memory has been removed is collected in the developing device, and the collected toner is reused for the next image formation.

[0006]

In the above-described image forming process, paper dust often adheres to the surface of the photosensitive drum. Examples of the generated paper dust include those generated when the paper is cut into a fixed form, and those generated when the paper comes into contact with rollers, guides, and the like when traveling in the machine. In addition, when recycled paper is used, generation of paper dust is particularly remarkable, and a large amount of paper dust adheres to the surface of the photosensitive drum. If such paper dust is not completely removed, exposure failure, development failure, transfer failure, etc. will occur at the location where the paper dust adheres, which will greatly hinder the next image formation. Would.

Therefore, it is a very important step to collect the paper dust together with the untransferred toner using the above-mentioned cleaner. In a cleanerless image forming apparatus that does not use a cleaner, the paper dust is collected together with the untransferred toner in the developing device. , The following problems occur. That is,
The original function of the developing device is to thin the toner in the toner hopper with a developing roller and a doctor blade, and to supply a certain amount of toner to the electrostatic latent image on the surface of the photosensitive drum. When paper is mixed, the paper powder is transported together with the toner by the developing roller to the doctor blade position, and there is a problem that the paper powder is clogged at that position.

That is, the particle size of the toner is approximately 10
２０20 μm, whereas the particle size of the paper dust is almost 0.3 mm or more. Therefore, the paper dust cannot pass through the doctor gap (the separation distance between the doctor blade and the developing roller). It is blocked by the doctor blade. When such a problem occurs, the portion where the paper powder is clogged at the doctor blade position is in a state where toner cannot be supplied to the electrostatic latent image on the photosensitive drum (a state where the toner is not developed), and the portion eventually becomes white. An image is formed as a dropout phenomenon.

From the above, it is desirable that the paper dust be removed by some method before being supplied to the transfer device. However, considering the original properties of the paper,
It is impossible to completely remove paper dust from paper,
Further, in the transfer step, it is necessary to always bring the paper into contact with the photosensitive drum once, so that it is inevitable that some paper dust adheres to the surface of the photosensitive drum.
Therefore, in a conventional cleanerless image forming apparatus which does not actively remove paper dust by a cleaner, it must be said that it is extremely difficult to completely remove paper dust on the photosensitive drum.

The present invention has been made in view of such circumstances, and provides a cleaner-less image forming apparatus capable of reliably forming an image by positively removing paper dust adhered on a photosensitive drum. The purpose is to do.

[0011]

According to the present invention, there is provided a cleaner-less image forming apparatus for dispersing toner remaining on an image carrier after transfer by a memory removing member, collecting the toner in a developing unit, and forming the next image. , a image bearing member surface after the transfer, the moving direction upstream position of the image bearing member than the residual toner dispersion position by the memory removing member, adhered to capture paper dust, the number to yield a predetermined amount of times The present invention is characterized in that a paper powder capturing and collecting brush made of fiber is brought into contact with the brush .

[0012]

According to the above construction, the paper dust capturing and collecting brush made of a large number of fibers is brought into contact with the surface of the image carrier after transfer,
The paper dust adhered to the surface is sequentially captured and collected in the gaps between the large number of fibers . The amount of paper dust collected is paper consisting of many fibers.
The amount is a predetermined amount according to the collecting ability of the powder capturing and collecting brush . Meanwhile, toner remaining on the image bearing member, such a large number of fibers
Therefore , the sheet is conveyed to a surface position of the image carrier on which the memory removing member is in contact without being captured by the paper dust capturing and collecting brush . Then, the residual toner is dispersed by the memory removing member, and the memory is removed. The image carrier from which the paper dust and the memory have been removed is continuously used for the next image formation.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a configuration diagram showing a main part of a cleanerless image forming apparatus according to the present invention. The operation will be described with reference to the drawings. First, the photosensitive drum 1 rotates in the direction indicated by the arrow A, and accordingly, the charger 2 charges the surface of the photosensitive drum 1. Next, the optical writing unit 3 emits light in response to an image signal given from a scanner unit (not shown), and exposes the surface of the photosensitive drum 1. Thus, an electrostatic latent image is formed on the exposed portion. Next, a developing device 4 provided on the right side of the photosensitive drum 1 in the drawing supplies toner to the electrostatic latent image to form a toner image (visible image).

In synchronization with the image forming process, a sheet (not shown) is supplied to a transfer device 5 provided opposite to the photosensitive drum 1 by a transport device (not shown), The toner image is transferred to the paper. The paper to which the toner image has been transferred is fixed to the toner by a subsequent fixing device (not shown), and then taken out of the apparatus. On the other hand, the photoreceptor drum 1 which has completed the transfer process is first subjected to a charge removing operation by a charge removing lamp 6 with its rotation, and then the paper dust removing brush 7 (see FIG. 2) in contact therewith removes paper dust. Then, the memory is removed by the abutted memory removing brush 8. Then, the photosensitive drum 1 from which the memory has been removed moves to the next image forming step. In the developing device 4 , the residual toner is collected and the next developing operation is performed.

A plus power source 9 is connected to the memory removing brush 8, and after the untransferred toner remaining on the photosensitive drum 1 is once collected on the brush by the electrostatic attraction force, the toner overflowing from the brush is removed. It is discharged onto the photosensitive drum again. By doing so, the residual toner is dispersed on the photosensitive drum 1, so that the memory is removed. Further, the developing unit 4 is connected to the negative power supply 10, the residual toner on the photosensitive drum 1 is collected in the developing device 4 by the electrostatic attraction force. The collected toner is reused in the developing unit 4 for the next development.

FIG. 2 is an enlarged side view showing the paper dust removing brush 7. As shown in FIG. The paper dust removing brush 7 captures and collects the paper dust attached to the photosensitive drum 1, and is provided so as to contact the surface of the photosensitive drum 1 by a holding member (not shown). The paper dust removing brush 7 is made of a carpet-like fabric, and includes a brush-like brush portion 70 and a base material 71 thereof. As a constituent material of the brush part 70, a fiber material having a large number of branch-like protrusions on its surface is used. In this embodiment, a processed yarn using rayon is applied. Of course, a spun yarn of another chemical fiber having a large number of branched protrusions formed on the surface can also be used. The thickness (corresponding to the hardness) of the fiber is appropriately selected so as not to damage the surface of the photosensitive drum 1.

The paper dust removing brush 7 is fixed to the holding member (not shown) by attaching the base material 71 with an adhesive tape. The brush density and the brush length are determined in consideration of the life of the photosensitive drum. Normal,
The replacement of the photosensitive drum 1 is intended to be performed about 30 to 30,000 copies, and accordingly, the brush unit 70 is formed so that the amount of paper dust generated from 30,000 to 30,000 sheets can be collected. It is desirable. This is very convenient because the replacement of the paper dust removal brush 7 can be performed together with the replacement of the photosensitive drum 1.

According to the above-described structure, the paper powder removing brush 7 is brought into contact with the surface of the photoreceptor drum 1 after the transfer, so that the fibers constituting the brush portion 70 have a net-like structure via the branch-like projections. Is formed, the paper dust on the photosensitive drum 1 is captured by the brush 70. Then, the captured paper dust is entangled with the branch-like projection and does not separate from the brush part 70. In addition, the paper dust holding capacity of the brush unit 70 corresponds to the amount of paper dust generated from 30,000 to 30,000 sheets of paper. It does not return to the surface of the photosensitive drum 1 again.

The particle size of the residual toner on the photosensitive drum 1 is about 10 to 20 μm, and the size of the paper powder (0.3
mm or more), the toner is not trapped by the paper dust removing brush 7. Therefore, after the residual toner has passed through the paper dust removing brush 7, the residual toner moves to a position where the memory removing brush 8 comes into contact, and receives a memory removing action. The present invention is also applicable to a cleaner type image forming apparatus.

[0020]

According to the present invention described above, in the cleanerless image forming apparatus, the paper dust removing means is brought into contact with the image carrier after transfer, so that the paper dust adhered to the image carrier is reliably removed. Can be removed. Further, since the paper dust is removed before the residual toner is dispersed by the memory removing member, the paper dust is captured by the memory removing member, and the captured paper dust returns to the image carrier again. Such a problem does not occur. As a result, no paper dust is collected in the developing unit, so that there is no hindrance to development. Therefore, in the cleanerless image forming apparatus, a white spot phenomenon due to paper dust does not occur in the formed image, and stable image formation can be performed.

Further, since the paper dust removing means has a collecting ability corresponding to a predetermined amount of paper dust to be predicted, it is not necessary to frequently replace the paper dust, and it is very convenient.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a main part of a cleanerless image forming apparatus according to the present invention.

FIG. 2 is an enlarged side view showing a paper dust removing brush.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoreceptor drum 4 Developing device 7 Paper dust removal brush 8 Memory removal brush

Claims (1)

(57) [Claims] 1. A cleanerless image forming apparatus for dispersing toner remaining on an image carrier after transfer by a memory removing member, collecting the toner in a developing unit, and forming an image in the next order, the surface of the image carrier after transfer. a is, in the moving direction upstream position of the image bearing member than the residual toner dispersion position by the memory removing member, adhered to capture paper dust, for yield a predetermined amount of times
A cleaner-less image forming apparatus, wherein a paper dust capturing and collecting brush made of a large number of fibers is brought into contact.