JPH049300B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrophotographic apparatus for erasing unnecessary latent image portions on a photoreceptor using erasing light irradiation means.

Generally, with electronic copying machines, users dislike images other than the original, such as shadows and dirt in non-image areas, being imprinted during copying.
Excess portions of the electrostatic latent image are erased by exposure before development.

This is necessary because when an image is reduced and imprinted, the area on the circumferential surface of the photoreceptor corresponding to the area outside the original area is not exposed to image light, so it is imprinted as solid black on the copy. Especially important.

For this reason, conventionally, as shown in FIG. 1, an electrostatic charge is applied to the circumferential surface of the photoreceptor 1 by a charger 2, and then a latent image is formed by exposing the image reflected by the illumination device of the document. At this time, an erasing lamp (erasing means) 4 is turned on to irradiate a non-exposed area on the circumferential surface of the photoreceptor 1 with light to erase the static charge.

As a result, a developed image is formed only in the necessary area, and this developed image is transferred to the transfer paper sent from the paper feeder by the transfer corona 5, and then fixed in the fixing device to complete the copying. Ru.

Further, after the transfer, the toner remaining on the circumferential surface of the photoreceptor 1 is neutralized by a static eliminator 6, and then scraped off by a cleaning blade 7 made of urethane rubber or the like and copied repeatedly. Ru.

However, conventionally, the erasing lamp 4 is always lit during the copying operation, and no image is formed on the circumferential surface of the photoreceptor 1, so the image erasure area on the circumferential surface of the photoreceptor 1 No toner adheres to the portion of the cleaning blade 7 corresponding to the photoconductor 1, and the blade 7 is brought into direct friction with the photoreceptor 1.

On the other hand, in the image forming area, the cleaning blade 7 and the photoreceptor 1 are rubbed together through the scraped toner. For this reason, there is a difference in the frictional force of the blade 7 between the image forming area and the image erasing area on the photoreceptor 1, and if this state continues for a long time, the characteristics of the photoreceptor 1 will change, resulting in uneven images. It was hot. In addition, the cleaning blade 7 and the photoreceptor 1 are connected to each other in a state where no toner is present.
If the cleaning blade 7 and the photoreceptor 1 are rubbed together for a long time, the cleaning blade 7 and the photoreceptor 1 will be seriously damaged, resulting in a shortened lifespan.

In addition, if you temporarily turn off the erasing lamp 4,
Alternatively, it is possible to reduce the difference in frictional force by forming a latent image locally in the image erasing area on the photoreceptor 1 by reducing the light, and then attaching a certain amount of toner after development. In this case, there is a problem that a latent image appears on the transferred image and stains the image.

The present invention has been made focusing on the above circumstances,
The purpose of this is to control the light irradiation by the erasing means to create a substantially band-shaped image across the entire width in the rotational direction within the third image forming area that does not touch any side of the image forming area on the image carrier. By causing the latent image to remain, the frictional force between the image carrier and the cleaning means is made uniform over its entire width, and even if the latent image is developed, it is prevented from being transferred to the transfer material. The present invention aims to provide an electrophotographic device.

The present invention will be described below with reference to an embodiment shown in FIGS. 2 to 4.

In the figure, reference numeral 12 denotes a latent image erasing means provided near one side of the rotatable electrophotographic photoreceptor 1 between the charger 2 and the developer 3 in the same way as shown in FIG. It is a lamp for use.

As shown in FIG. 4, the circumferential surface of the electrophotographic photoreceptor 1 has an image forming area 16 in its rotational axis direction a and rotational direction b, where an image-exposed latent image is developed and transferred to a transfer material; The image erasing area 13 is divided into an image erasing area 13 where no image is transferred to the transfer material, and the image erasing area 13 adjacent to the image forming area 16 on one side in the rotation axis direction a is defined as a first image erasing area 21. The image erasing area 13 that is adjacent to each other on one or two sides in the rotation direction b is defined as a second image erasing area 22, and the image erasing area 13 that is not in contact with any side of the image forming area 16 is defined as a third image erasing area 23.

The erasing lamp 12 is set at the cutoff point A of the image forming timing corresponding to the size of the transfer paper, as shown in a in FIG.
At the break B of the image forming timing, the light is turned off under the control of the control means 25, facing the third image erasing area 23 on the circumferential surface of the photoreceptor 1.

During image formation, the image forming area 16 on the peripheral surface of the photoreceptor 1 is irradiated with reflected light from the original to form a latent image in the same manner as shown in FIG. The erase area 21 is illuminated with light by turning on the erase lamp 12 to erase static charges. As a result, only the original image is converted into a toner image in the developing device 3, and transferred onto a transfer paper in the transfer device 5. After this transfer, residual toner on the photoreceptor 1 is neutralized by a static eliminator 6 and then scraped off by a cleaning blade 7.

On the other hand, during the image formation described above, the photoreceptor 1
When is rotated by a predetermined amount, image formation is completed and the third image erasing area 23 on the circumferential surface of the photoreceptor 1 is opposed to the erasing lamp 12. At this time, the erasing lamp 12 is turned off, so that a latent image 15 is formed in the third image erasing area 23 on the photoreceptor 1 in the form of a band over substantially the entire width in the rotation direction b.

After this latent image 15 is turned into a toner image in the developing device 3, it is sent to the cleaning blade 7 and the toner is scraped off without being transferred to the transfer paper by the transfer device 5. The cleaning blade 7 comes into sliding contact with the third image erasing area 23 and the first image erasing area 21 via the scraped toner.

As described above, the latent image 15 is formed in a band shape over substantially the entire width of the photoreceptor 1 in the rotational direction b in the third image erasing area 23 that is not in contact with any side of the image forming area 16 on the circumferential surface of the photoreceptor 1. In order to form an image erase area 13
The portion of the cleaning blade 7 corresponding to the image forming area 16 is rubbed by the toner, and the frictional force of the cleaning blade 7 corresponding to the photoreceptor 1 is made uniform.

Further, the third image erasing area 23 is the image forming area 1
6, the toner image formed in the third image erasing area 23 is not transferred to the transfer paper.

Note that in the above embodiment, the erase lamp 12
Although the light is turned off, the present invention is not limited to this, and even if the light is dimmed, the same effect as in the above embodiment can be obtained.

As described above, the present invention forms a latent image in the form of a band over substantially the entire width of the photoreceptor 1 in the rotation direction of the photoreceptor 1 in the third image erasing area that is not in contact with any side of the image forming area on the peripheral surface of the image carrier. In order to form an image, the part of the cleaning means corresponding to the image erasing area is rubbed through the developer in the same way as the part corresponding to the image forming area, and the frictional force of the cleaning means corresponding to the image carrier is made uniform. become.

Therefore, unlike in the past, there is no change in the characteristics and unevenness of the image, and there is less damage to the image carrier and the cleaning means, resulting in a longer service life. The formed image is not transferred to the transfer paper, and the effect is that the image is not smudged.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing a conventional example, and FIGS. 2 to 4 show an embodiment of the present invention.
The figure is a perspective view showing the photoreceptor and the erasing lamp, Figure 3 is a graph showing the relationship between the timing of turning on and off the erasing lamp and the image forming area, and Figure 4 is the image formation on the circumferential surface of the photoreceptor. FIG. 3 is an explanatory diagram showing areas and image deletion areas. 1... Electrophotographic photoreceptor (image carrier), 3... Developing device (developing means), 5... Transfer corona (transfer means), 7... Cleaning blade (cleaning means),
12... Erasing lamp (erasing means), 13... Image erasing area, 15... Latent image, 16... Image forming area, 21... First image erasing area, 22... Second image erasing area, 23... ...Third image erasing area.

Claims (1)

[Scope of Claims] 1. A latent image forming means for forming a latent image by imagewise exposure on a rotatable image carrier, and developing the latent image formed by the latent image forming means using a developer. a developing means for transferring an image developed by the developing means to a transfer material; and a cleaning means for removing developer remaining on the image carrier after the transfer process by the transferring means. , an erasing means for irradiating the image carrier with a predetermined amount of light so that the portion irradiated with the light is not developed by the developing means regardless of whether or not it has been image-exposed; and a control means. In an electrophotographic apparatus, the rotating circumferential surface of the image carrier is arranged in the direction of its rotational axis and in its rotational direction to an image forming area where the image is exposed, the image is developed, and is transferred to the transfer material, and an image is formed on the transfer material. The image erasing area is divided into image erasing areas that are not transferred, and the image erasing area that is adjacent to the image forming area on one side in the rotational axis direction is defined as a first image erasing area, and the image erasing area is adjacent to the image forming area on one side or two sides in the rotational direction. The image erasing area is a second image erasing area, and the image erasing area that is not in contact with any side of the image forming area is a third image erasing area, and the control means controls the operation or light amount of the erasing means to erase the image from the third image erasing area. 3. A substantially band-shaped latent image is formed within the image erasing area over substantially the entire width in the rotation direction, this latent image is developed by the developing means, and the developed image is transferred to a transfer material by the transfer means. An electrophotographic apparatus characterized in that the cleaning means removes the image without transferring the image to the surface of the electrophotographic apparatus.