JPH1152754A - Electrophotographic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent toner from being scattered to the periphery of an image and to stably obtain the high-quality image by regulating the exposure wavelength of a pretransfer discharging means to be longer than the exposure wavelength of an electrostatic latent image forming means. SOLUTION: Since the exposure wavelength of the pretransfer discharging device 6 is set to be longer than the exposure wavelength of an exposure device 3 and is the wavelength in an area where sensitivity is 0.1 to 0.4 times as high as the sensitivity of a photoreceptor 1 in the exposure wavelength of the device 3, carrier is produced at the deep part of the carrier producing layer of the photoreceptor 1, whereby charge moving speed is low and the surface potential of the photoreceptor is gently lowered (generally, the light of short wavelength produces the carrier at the shallow part of the carrier producing layer and the light of long wavelength produces the carrier at the deep part of the carrier producing layer). By gently lowering the surface potential of the photoreceptor, irregularity in a developed image caused by toner scattering is eliminated. Then, by using the wavelength in the area where the sensitivity of the photoreceptor 1 is low, discharge light quantity is easily adjusted and discharge with appropriate light quantity is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus and, more particularly, to uniformly exposing a photosensitive member holding a developed image to a photosensitive member before transferring the developed image formed on the photosensitive member to a recording material. The present invention relates to an electrophotographic apparatus having a pre-transfer static elimination means for eliminating static electricity.

[0002]

2. Description of the Related Art An electrostatic latent image having a non-exposed portion and an exposed portion is formed on a photoreceptor by an electrostatic latent image forming means, and a developer is attached to the exposed portion to form a developed image on the photoreceptor. An electrophotographic process in which the photosensitive member holding the developed image is uniformly exposed to remove electricity is disclosed in, for example,
JP-A-168188, JP-A-61-183681, JP-A-62-30286 and JP-A-12-2
No. 74186.

[0003]

By the way, in the conventional pre-transfer static elimination technology, the exposure wavelength of the pre-transfer static eliminator is set at an area where the sensitivity of the photosensitive member is high, that is, for recording and forming an electrostatic latent image on the photosensitive member. 3 is set to a region close to the exposure wavelength of the electrostatic latent image forming means (exposure device), and the carriers are generated on the surface of the carrier generation layer constituting the photoreceptor. As shown by the broken line, the surface potential of the photoreceptor suddenly dropped too much, and the toner forming the developed image was liable to be scattered, causing a problem that the developed image was disturbed. Further, it is difficult to adjust the amount of light for the neutralization by the wavelength in the region where the sensitivity of the photosensitive member is high, and it is technically difficult to eliminate the static electricity with an appropriate amount of light.

Accordingly, it is an object of the present invention to provide an electrophotographic apparatus capable of stably obtaining a high-quality image without toner scattering around the image. Another object of the present invention is to make it possible to easily adjust the amount of static elimination light and to eliminate static electricity with an appropriate amount of light.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an electrostatic latent image forming means for forming an electrostatic latent image having a non-exposed portion and an exposed portion on a photoreceptor, and a developer attached to the exposed portion. Developing means for visualizing the exposed portion as a developed image, pre-transfer charge removing means for uniformly exposing the photosensitive member holding the developed image to remove static electricity, and developing the developed image on the photosensitive member after removing the static electricity on a recording material. In an electrophotographic apparatus having a transfer means for transferring, the exposure wavelength of the pre-transfer static elimination means is set to be longer than the exposure wavelength of the electrostatic latent image forming means.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 denotes a photosensitive drum, which is rotatably provided in a direction indicated by an arrow. Reference numeral 2 denotes a charger for uniformly charging the surface of the photosensitive drum 1, and 3 denotes an electrostatic latent image forming apparatus (hereinafter, referred to as “hereinafter”) that scans and exposes the charged photosensitive drum 1 with a laser beam to record and form an electrostatic latent image on the photosensitive drum 1. A developing device for attaching toner 5 to a portion (exposed portion) of the electrostatic latent image formed on the photosensitive drum 1 by irradiation of the laser beam, where the charge has disappeared; Reference numeral 6 denotes a pre-transfer static eliminator (to be described in detail later);
This is a transfer device that transfers the image to the printer.

Next, in the above configuration, the photosensitive member is Se.
In addition to the case where a -Te type photoreceptor is used, Se-
The relationship between the sensitivity of the Te-based photoconductor and the exposure wavelength will be described with reference to FIG. As shown in FIG. 2, the exposure wavelength of the pre-transfer static eliminator 6 is set to be longer than the exposure wavelength of the exposure device 3, and is 0.1 times the sensitivity of the photoconductor 1 at the exposure wavelength of the exposure device 3. Since the wavelength is in the range of .about.0.4 times, carriers are generated deep in the carrier generation layer of the photoconductor 1, so that the charge transfer speed is slow, and the photoconductor surface potential is gradually lowered as shown in FIG. (In general, short-wavelength light generates carriers in a shallow portion of the carrier generation layer, and long-wavelength light generates carriers in a deep portion of the carrier generation layer).

As described above, in the electrophotographic apparatus according to the present invention, since the surface potential of the photosensitive member is gradually lowered, the disturbance of the developed image due to the scattering of the toner as described in the prior art does not occur. In addition, by using a wavelength in a region where the sensitivity of the photosensitive member is low, the amount of charge removal can be easily adjusted, and charge can be removed with an appropriate amount of light.

[0009]

According to the present invention, it is possible to provide an electrophotographic apparatus capable of stably obtaining a high-quality image without scattering toner around the image.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the relationship between the sensitivity of a photoreceptor and the exposure wavelength in the present invention.

FIG. 3 is an explanatory diagram showing a relationship between photoconductor surface potentials in a charge removal process.

[Explanation of symbols]

Reference numeral 1 denotes a photosensitive drum, 2 denotes a charger, 3 denotes an exposure device, 4 denotes a developing device, 6 denotes a pre-transfer neutralization device, and 8 denotes a transfer device.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Katsuhiro Shinohara, Inventor 1060 Takeda, Hitachinaka-shi, Ibaraki Prefecture Inside Hitachi Koki Co., Ltd. (72) Inventor Hisashi Nakajima 1060 Takeda, Hitachinaka-shi, Ibaraki Hitachi Koki Machinery Co., Ltd.

Claims (2)

[Claims] An electrostatic latent image forming means for forming an electrostatic latent image having a non-exposed portion and an exposed portion on a photosensitive member; and a developer attached to the exposed portion to visualize the exposed portion as a developed image. An electronic device comprising: a developing unit for causing the photosensitive member holding the developed image to be uniformly exposed to remove static electricity before transfer; and a transfer unit for transferring the developed image on the photosensitive member after the neutralization to a recording material. In the photographic apparatus, the exposure wavelength of the pre-transfer static elimination means,
An electrophotographic apparatus, wherein the wavelength is defined to be longer than the exposure wavelength of the electrostatic latent image forming means. 2. The sensitivity of the photoreceptor at the exposure wavelength of the pre-transfer static eliminating means is a wavelength in a range of 0.1 to 0.4 times the sensitivity of the photoreceptor at the exposure wavelength of the electrostatic latent image forming means. 2. The electrophotographic apparatus according to claim 1, wherein: