JPH0450976A - Developing device for electrophotographic device - Google Patents

Abstract

PURPOSE:To prevent the sticking of toners to a cap part by turning off the bias voltage to be impressed to a developing sleeve when the cap consisting of a conductive member faces the developing sleeve. CONSTITUTION:The cap part which consists of the conductive part and is provided in the aperture of a drum formed as a part for taking out photosensitive sheets and the non-image part of the photosensitive body 2 are maintained at the same potential. The bias voltage 6 to be impressed on the developing sleeve 4 is turned off by an on-off device 7 when the cap 1 faces the developing sleeve 4. Consequently, the electric field between the gap 1 and the developing sleeve 4 is kept larger than the image force of the cap 1. The sticking of the toners to the cap par 1 is prevented in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a developing method for an electrophotographic apparatus using a photoreceptor drum of a photoreceptor sheet winding type.

[Background of the invention]

The disadvantages of the prior art will be explained below with reference to FIG.

FIG. 2 shows a photoreceptor 2 and a developing device 3 in an electrophotographic apparatus. Although not shown, an electrostatic latent image formed through a charging and exposure process is applied to a developing sleeve 4 using a bias voltage. 6 is applied to develop the image.

In addition, the cap 1 is attached to the photoreceptor sheet so that the toner 5 does not electrostatically adhere to the cap surface when the cap portion 1 provided at the drum opening, which serves as the photoreceptor sheet take-out portion made of a conductive member, passes through the developing device 3. The potential is the same as that of the non-image area.

However, if the cap 1 is an insulator, uneven charging will occur and it will get dirty, so in the conventional technology where a conductive member is used for the cap 1,
Since the mirror image force acting between the cap 1 and the toner 5 is larger than the electric field of the developing sleeve 4, the toner 5 adheres to the cap 1, resulting in an increase in the amount of toner 5 consumed and The cleaning of step 5 causes the cleaning brush to get dirty and the charger to get dirty, which is one of the causes of lowering the reliability of the device.

[Purpose of the invention]

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to prevent toner from adhering to the cap portion made of a conductive member of this type of photoreceptor.

[Summary of the invention]

In the present invention, an electrostatic attraction force of the toner toward the sleeve is exerted between the cap and the developing sleeve due to an electric field between the cap provided at the drum opening, which serves as a photoreceptor sheet takeout section made of a conductive member, and the developing sleeve. It was designed to increase the electric field between the cap and the developing sleeve by focusing on the fact that toner will not adhere to the cap if it is larger than the mirror image force.

[Embodiments of the invention]

A specific embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows a photoreceptor 2 and a developing device 3 in an electrophotographic apparatus, and although not shown, an electrostatic latent image formed through a charging and exposure process is developed on a developing sleeve 4. This is done by applying a bias voltage of 6.

In addition, the cap portion 1 provided at the drum opening, which serves as the photoreceptor sheet take-out portion made of a conductive material, and the non-image portion of the photoreceptor 2 are set at the same potential, and when the cap 1 faces the developing sleeve 4, the developing sleeve A bias voltage 6 applied to 4 is turned on and off by an on/off device 7. As a result, the electric field between the cap 1 and the developing sleeve 4 can be made larger than before, and at the same time, the electric field can be made larger than the mirror image force of the cap 1.

This relationship between the image force and the electric field makes it possible to prevent toner from adhering to the cap portion.

〔Effect of the invention〕

According to the present invention, it is possible to make the electric field between the cap provided at the drum opening, which serves as the photoreceptor sheet take-out section made of a conductive member, and the developing sleeve larger than the mirror image force of the cap, so that toner consumption due to toner adhesion to the cap is prevented. It is possible to suppress the increase in the amount of toner, prevent the cleaning brush from becoming dirty and the charger from getting dirty due to this toner cleaning, and improve the reliability of the apparatus.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an embodiment of an electrophotographic apparatus according to the present invention, and FIG. 2 is a schematic diagram showing a part of an electrophotographic apparatus according to the prior art. In the figure, 1 is a cap, 2 is a photoreceptor, 4 is a developing sleeve, 6 is a bias voltage, and 7 is a N10FF device. First Nagi patent applicant name Hitachi Koki Co., Ltd. zrb

Claims (1)

[Claims] The photoreceptor drum on which the photoreceptor on which the transferred image is formed is a drum of a photoreceptor sheet winding type,
When the cap provided on the drum opening, which serves as the photoreceptor sheet take-out section, is made of a conductive material, and the cap made of the conductive material is opposed to the developing sleeve in an electrophotographic apparatus of a reversal development method using a bias development method, A developing method for an electrophotographic apparatus, characterized in that a bias voltage applied to a developing sleeve is turned off.