JPS62164062A - Electronic photograph device - Google Patents

Abstract

PURPOSE:To obtain a good quality reproducing image having no black stripe etc., by preventing the sticking of a toner to an unnecessary part on a photosensitive body as well as minimizing the unnecessary toner consumption by comparing an exposing area size and a transferring material size on the photosensitive body, setting a blank exposing area based on the smaller size and executing the destaticization. CONSTITUTION:When a variable power ratio and a transfer material cassette corresponding to it is selected by the operation of a magnification key and a cassette selecting key on a control panel, the transfer material size concerning the selected cassette is read and inputted to the processor. Based on the input information, data DATA 1 of a blank exposing width corresponding to the transfer material size stored beforehand are read. When the selected variable power is 100% or above, namely, a nonmagnification or magnifying mode, a lamp to be lighted up of a blank exposing device 21 in accordance with the DATA 1, that is, the lamp corresponding to the blank exposing width is determined, and by lighting up the lamp, the blank exposure is executed and the area is destaticized.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention uniformly covers the surface of a photoreceptor, and then irradiates the same magnification A according to the original with a variable magnification L1' to form a latent image. a latent image forming device for forming a latent image, a developing device for converting the latent image into a visible powder image, a four-way device for converting the powder image onto a transfer material, and a width direction end of the photoreceptor provided upstream of the developing device. The present invention relates to a type of electrophotographic apparatus having a blank exposure device that exposes a set area of a part to light and eliminates static electricity from the area.

[Conventional technology]

In so-called variable magnification type electrophotographic devices that can reduce or enlarge the original image for copying, the size of the original image after changing the magnification (hereinafter referred to as latent image size) does not match the size of the transfer material on which it is transferred. This tendency is particularly strong in electrophotographic devices that use a zoom lens or the like and can arbitrarily change the magnification. In this case, for example, if the latent image size is larger than the transfer material size, unnecessary toner will adhere to areas on both end sides of the photoreceptor that are not used for transfer. This unnecessary toner is directly removed by the cleaner and discarded, which is very uneconomical, increases the burden on the cleaner, and causes transfer corona.

For this reason, conventionally, a blank exposure device extending along the width direction of the photoconductor is provided upstream of the developing device, and the blank exposure device exposes unnecessary areas on the photoconductor according to the size of the transfer material to remove static electricity. A device has been proposed that performs control to prevent toner from adhering to the area. Further, as another device, for example, Japanese Patent Application Laid-Open No. 56-5927
As disclosed in Japanese Patent Application No. 7, an apparatus has been proposed that compares the latent image size and the transfer material size and performs control to eliminate static electricity from an unnecessary area set according to the smaller size.

[Problem that the invention seeks to solve]

However, in the conventional configuration, for example, in the first device, there is no problem when the transfer material size is larger than the latent image size, especially when it is larger than the exposure area size on the photoreceptor determined by the magnification. These factors have not been taken into consideration. Figure 2 shows a case where the size of the transfer material is larger than the exposure area, but in the above device, the area on the photoreceptor that is outside the exposure area and is smaller than the size of the transfer material is not neutralized. Because the dark area potential is maintained, unnecessary toner adhesion occurs during development, and this toner is transferred to both sides of the transfer material during the transfer process, forming a black band, which deteriorates the quality of copies and objects. have points.

In addition, in the second conventional device, for example, when the document to be used has an arbitrary size other than the size specified by the JIS standard, it is possible to detect the size and also detect it as the size after scaling. This method has problems such as requiring complicated detection means.

The present invention has been made to solve the problems of the conventional devices as described above.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention compares the size of the exposure area on the photoconductor determined by the magnification and the size of the transfer material in the above-mentioned type of electrophotographic apparatus, and uses the smaller size as a reference. The present invention is characterized in that an exposure area is set by the blank exposure device.

[Effect]

With the above configuration, the blank exposure device exposes an unnecessary area on the surface of the photoreceptor based on the smaller of the transfer material size or the exposure area size prior to development, and erases the dark area potential of the area. Prevents unnecessary toner from adhering to the body surface.

〔Example〕

The illustrated embodiment is an example in which the present invention is applied to an ordinary electrophotographic apparatus, and this apparatus has a photosensitive drum 2 mounted within a main body 1 and capable of rotating in the direction of arrow A in FIG. After the surface of the photosensitive drum 20 is charged to a single charge by the charging device 3, an optical device including a lens 4 and several mirrors 5 forms an optical image of the same magnification or variable magnification according to the image of the document 7 on the document table 6. is irradiated, forming a static latent image consisting of bright and dark potentials. The variable magnification image is set, for example, by changing the optical path length of the optical device and changing the scanning speed of the document table according to the magnification key on the operation panel provided on the top surface of the main body 1. Next, the electrostatic latent image is made into a visible powder image by applying toner to the dark potential portion of the electrostatic latent image by the developing device 8, and is placed on a transfer material 11 fed from a cassette selected from a plurality of transfer material cassettes 9. transcribed. code 12
Reference numeral 13 indicates a transfer discharge device for performing the transfer, and a separation discharge device 13 assists in separating the transfer material from the photosensitive drum.The separated transfer material is fixed with a powder image by a fixing device 14, and then Expelled outside. Incidentally, reference numeral 15 denotes a cleaner, which removes toner remaining on the photosensitive drum and provides the photosensitive drum for reuse.

The document table 6 is provided with a glass plate 16 for placing a document in the center, and is scanned in the direction shown by arrow B in FIG. 1 by a drive device (not shown) and moved backward. During this scanning, the original 7 placed on the original platen 6 is subjected to slit exposure by the exposure device 17, and a light image corresponding to the original image is formed. As shown in FIG. 2, the width of the slit exposure area relative to the document table is set to the width a of the copyable plate 16 plus some extra width. The lower surface of the original platen 6 and the lower surface of the original platen cover 18 included in this exposure area are formed in white so that the corresponding photosensitive drum surface has a bright area potential during copying. The exposed area is irradiated onto the surface of the photosensitive drum at the same magnification, and therefore the size of the exposed area on the photosensitive drum increases or decreases depending on the magnification ratio.

As shown in FIG. 1, the blank exposure device designated by the reference numeral 21 is arranged vertically from the charging device 3 to the developing device 8 and relatively close to the surface of the photosensitive drum. The blank exposure device 21 includes a lamp group 22 consisting of a plurality of lamps 22a such as LEDs arranged in tandem in the width direction of the photosensitive drum 2, and a base 23 thereof. The blank exposure area to be set is sufficiently exposed so as to determine the position corresponding to the widthwise boundary of the area and the position corresponding to the widthwise boundary of each transfer material size available in the electrophotographic apparatus. They are arranged at appropriate intervals to allow for

The positions of these lamps are stored in storage means such as ROM of the processor, and they are turned on and off individually by appropriate signals, and only the lamps corresponding to the areas other than the required area on the photoreceptor are turned on. Eliminate static electricity in the area. still,
In some cases, in order to clarify the boundary, a partition plate may be placed at a position corresponding to the boundary to divide the lamp group 22 into several groups for control.

FIG. 4 is a flowchart showing the control operation of the blank exposure device of the electrophotographic apparatus according to the present invention 1/c.

Such control is performed by a microprocessor consisting of a C'PU, ROM, %RAM, etc.

When a magnification ratio and a corresponding transfer material cassette are selected by operating a magnification key and a cassette selection key (both not shown) on the operation panel, the transfer material size related to the selected cassette is read and input to the processor. Based on this input information, pre-stored blank exposure width data (referred to as DATA 1) corresponding to the transfer material size is read. the selected magnification ratio is took or more;
In other words, when in the same size or enlarged mode, this DATA
Accordingly, a lamp to be lit in the blank exposure device 210, that is, a lamp corresponding to the blank exposure width (exposure area) is determined, and by lighting the lamp, blank exposure is performed and static electricity is removed from the area. On the other hand, the magnification is 100
In other words, in the case of reduction mode, the exposure area size on the photosensitive drum is calculated from the exposure area size a + b on the document table and the magnification ratio, and the blank exposure corresponding to this exposure area size is calculated. Width data (called DATA2)
is calculated. This DATA2 is compared with the DATAL, and if DATA2 is smaller than DATAI, DATA
Based on ATA2, if DATA2 is larger than DATA1, a blank exposure area is set based on DATA1, and the corresponding lamp 22a of the blank exposure device is turned on to eliminate static in the area.

〔Effect of the invention〕

As described above, according to the present invention, static electricity is removed by setting a blank exposure area based on the smaller size of the exposure area on the photoreceptor and the transfer material size, so that unnecessary areas on the photoreceptor are It is possible to prevent toner from adhering to the toner, minimize unnecessary toner consumption, and provide high-quality reproduced images without black bands or the like.

Furthermore, the above-described configuration does not require a complicated document size detection device, so the entire electrophotographic apparatus can be simplified and made more compact.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an example of an electrophotographic apparatus to which the present invention is applied, FIG. 2 is a schematic explanatory diagram of the part of the apparatus shown in FIG. 1, and FIG.
The figure is a side view showing an example of a blank exposure device, and FIG. 4 is a flowchart showing the control operation of the blank exposure device. 2... Photosensitive drum, 3... Charging device, 6...
- Document table, 8...Developing device, 21...Blank exposure device. Purity of drawings! ! X (No change in content) Head 3 Figure 2τ Procedure amendment writing method) % formula % 1 Display of case Patent Application No. 6817 of 1988 2 Title of invention Electrophotographic device 3 Person making amendment Relationship with case Patent applicant Otaku Yaguchi Address 4, Tsuragawa Denki 5-17 Yaro-chome, Ota-ku, Tokyo Date of amendment order 5 Drawings subject to amendment. 6. Contents of the amendments Figures 1 to 3 of the drawings originally attached to the application are printed and
As shown in the attached sheet (no changes in content). 7 List of attached documents

Claims (1)

[Claims] A latent image forming device that uniformly charges the surface of a photoreceptor and then irradiates a light image with a constant magnification or variable magnification depending on the original to form a latent image, and a developing device that converts the latent image into a visible powder image. , a type having a transfer device that transfers the powder image onto a transfer material, and a blank exposure device that is provided upstream of the developing device and that exposes a set area at the end of the photoreceptor in the width direction and removes static electricity from the area. In the electrophotographic apparatus, the size of the exposure area on the photoreceptor determined by the magnification and the size of the transfer material are compared, and the exposure area by the blank exposure device is set based on the smaller size of the other. electrophotographic equipment.