JP2912971B2 - Electrophotographic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention forms a reference latent image on a photoreceptor, develops the latent image into a reference pattern, detects the density of the reference pattern, and determines the detected density. And an electrophotographic apparatus having a magnet brush cleaning device while controlling the concentration of the developer so as to fall within the range.

[Conventional technology]

2. Description of the Related Art In an electrophotographic apparatus, a reference latent image is formed on a photoreceptor, developed and used as a reference pattern, the pattern density is detected, and the developer density (toner density) is controlled so that the detected density is constant. Methods are known.

On the other hand, a magnet brush cleaning device (hereinafter referred to as a "mag brush cleaning device") is widely used as a cleaning device.

[Problems to be solved by the invention]

The magnet brush cleaning device of the electrophotographic apparatus has a drawback that when the amount of toner on the surface of the cleaning carrier decreases, the carriers directly rub against each other, and the cleaning carrier deteriorates early.

For this reason, a document having a normal area ratio can be dealt with by setting the conditions for collecting the toner from the cleaning agent to an appropriate place, but when the user takes a large number of images having an extremely low area ratio. There is a problem in that the cleaning carrier deteriorates in the non-image area on the photoreceptor, and the cleaning agent must be frequently replaced.

The present invention is based on the premise that the toner concentration control method described above is employed, so that the toner in the cleaning agent of the mag brush cleaning device can be prevented from being extremely reduced, and the life of the cleaning agent can be guaranteed regardless of the use conditions of the user. The purpose is to be.

[Means for solving the problem]

The object is to form a reference latent image on a photoreceptor, develop the reference latent image into a reference pattern, detect the density, and control the density of the developer so that the detected density falls within a predetermined range. In addition, in an electrophotographic apparatus having a mag brush cleaning device extending in the width direction of the photoconductor and cleaning the photoconductor, the width of the reference pattern formed on the photoconductor is changed by the cleaning of the mag brush cleaning device. This is achieved by providing an eraser whose lighting width with respect to the reference pattern is controlled to be substantially equal to the width.

[Action]

An eraser composed of an LED or EL irradiates light to, for example, both ends of the reference latent image such that the width of the reference latent image is substantially equal to the width of the mag brush cleaning device. As a result, the reference pattern obtained by development is also substantially equal to the cleaning width, and the concentration of the cleaning agent is uniform over the length in the longitudinal direction of the mag brush cleaning device (the width direction of the photoreceptor). It is possible to prevent the toner concentration in the inside from being reduced.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of an electrophotographic apparatus according to one embodiment of the present invention. The process will be briefly described. After a photoconductor 2 is charged by a charging device 1, an image is exposed. After the exposure, an electrostatic latent image is formed on the photoconductor 2. This electrostatic latent image is developed by the developing device 3 as a toner image.
The developed toner image is transferred onto transfer paper by a transfer / separation device 4, and the transfer paper is discharged onto a copy tray 6 via a fixing device 5. After passing through the transfer / separation device 4, toner and paper powder that have not been transferred to the transfer paper adhere to the transfer paper, and are cleaned by the mag brush cleaning device 7. Thus, the photosensitive member 2 is again in a state where image formation is possible.

In the course of such an image forming process, the toner concentration of the toner and the developer in the developing device 3 decreases. In the present embodiment, the following method is used as the toner density control method. That is, a fixed reference latent image is formed between images, developed to form a reference pattern, and the pattern density is detected by a sensor 8 comprising a light receiving element. When the pattern density falls below a certain value, the toner is replenished into the developer.

The reference latent image is obtained by attaching a patch of a fixed density to a corner of the contact glass 10, temporarily dropping the output of the charging device 1 between the images, and irradiating both ends with an eraser 11,
It is created after regulating the width.

The present invention is characterized in that the eraser 11 is controlled to be turned on to make the width of the reference latent image, that is, the width of the reference pattern after development substantially equal to the cleaning width.

FIG. 2 is an explanatory view for comparing the reference pattern widths of the conventional example and the present invention. The conventional reference pattern 9 has a small quadrangular shape formed at the center in the width (L _OPC ) direction of the photosensitive member 2. Things.

However, the reference pattern 12 of this embodiment Yes by expanding to the cleaning width L _CL mug brush cleaning device 7,
Thereby, an extreme decrease in toner concentration of the mag brush cleaning agent is suppressed. This is achieved by changing the lighting width of the eraser 11.

Generally, the eraser 11 is configured by arranging a large number of LEDs. In a copying machine for forming an image based on the center of the photoconductor in order to form the reference pattern 9, the LEDs must be finely arranged to unnecessary places. However, when the reference pattern width is increased as in the present embodiment, the portion corresponding to the minimum copy size is replaced with another light source such as EL,
It will be possible to reduce the number of LEDs by making them larger and reduce the cost.

In addition, since the reference pattern is formed over the cleaning width of the mag brush and toner is input, the concentration of the cleaning agent does not drop extremely along the longitudinal direction of the mag brush cleaning device. There is no need to attach a horizontal stirring mechanism. In this regard, costs can be reduced.

〔The invention's effect〕

As described above, according to the present invention, since the reference pattern for controlling the toner density is extended to the cleaning width of the mag brush cleaning device, the toner of the mag brush cleaning agent can be used in any use mode of the user. The concentration does not decrease too much, so that the performance of the cleaning agent can be maintained for a long time.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an electrophotographic apparatus according to one embodiment of the present invention, and FIG. 2 is an explanatory diagram for comparing a reference pattern width of a conventional example with that of the present invention. 11 ... Eraser, 12 ... Reference pattern.

Claims (1)

(57) [Claims] 1. A reference latent image is formed on a photoreceptor and developed to form a reference pattern. The density of the reference pattern is detected, and the density of the developer is controlled so that the detected density falls within a predetermined range. And an electrophotographic apparatus having a magnet brush cleaning device extending in the width direction of the photoconductor and cleaning the photoconductor, wherein the width of the reference pattern formed on the photoconductor is the same as that of the magnet brush cleaning device. An electrophotographic apparatus comprising an eraser for controlling a lighting width with respect to the reference pattern so as to be substantially equal to a cleaning width.