JPS60247662A - Method for erasing needless image area of sensitive material - Google Patents

Abstract

PURPOSE:To enable erasion in an optimum erasion width so as not to develop a needless toner image by using the width of a paper as a standard when magnification is 1, and when it is <1, comparing the product of the width of an original platen and magnification ratio with the paper width, using a smaller value of them as a standard, and setting the eration width. CONSTITUTION:Side erasing lamps 17 are arranged in parallel to the axial direction of a photosensitive drum 8, and comprises lamps 24-26. The lamps 17 are controlled in accordance with the paper width and magnification before a latent image formed on the drum 8 is not developed so that a number of lamps corresponding to the paper width, when magnification is >=1, are turned on. When it is <1, it is controlled that a number of the lamps 17 corresponding to a smaller value selected from the product of the platen width and the reduction ratio, and the paper width.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of partially erasing an unnecessary image area of a photosensitive material by irradiating the unnecessary image area with light by turning on an erasing light source.

[Prior art]

When charging, exposing, and developing a photoreceptor in equipment such as a copying machine, the width of the photoreceptor is the width of the largest sheet of paper that can be copied (for example, 88
297 [■])), the surface of the photoconductor is always charged prior to exposure during copying, and when light hits the photoconductor due to exposure, the charging potential is lowered, Even after passing through the developing device, no toner image is deposited, but in the case of reduced copying, the exposure width on the photoreceptor becomes smaller, so charges remain at the edges and unnecessary toner images adhere there. . This causes the problem of increased toner consumption and contamination of the inside of the machine due to exceeding the storage capacity of the cleaning section, so it is desirable to erase the unnecessary image area, that is, eliminate the charge.

Conventionally, as a countermeasure for such cases, side erase lamps that eliminate static electricity have been provided opposite the edge of the photoconductor surface, and the number of lamps has been prepared in accordance with the stage of reduction. However, in the case of copying small sheets of paper, the toner is deposited on the area between the side erase lamp and the paper. [Object of the Invention] This invention was made in view of the above points, and The purpose of this is to enable erasing with an optimal erasing width so that unnecessary toner images are not developed.

[Structure of the Invention] In order to achieve the above object, the present invention sets the erasing width based on the paper width in the case of normal magnification, and sets the erasing width based on the width of the paper in the case of reduction, and sets the erasing width based on the width of the manuscript table and the magnification in the case of reduction. The multiplied value is compared with the paper width, and the erase width is set based on the smaller of the two.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 1 is a schematic diagram of the interior of a copying machine to which this invention is applied.
In addition to having a transfer process after the charging, exposure, and development processes,
A plurality of side erase lamps that can be turned on independently are capable of multi-step reduction and enlargement, and have the purpose of detecting the paper size and erasing unnecessary parts at both ends of the latent image on the photoreceptor. This shows the case of a copying machine equipped with

In the figure, (1) is a document table, (2) is a scanning lamp for exposure, (3) to (6) are mirrors, and (7) is a lens.
The optical image created by scanning the original on the original platen (1) with the scanning lamp (2) and mirror (3) is
An image is formed on the surface of the photosensitive material, in the example shown, on the photosensitive drum (8) via the mirrors (4) to (6) and the lens (7). In the case of reduction and enlargement, the vertical magnification is determined by varying the scanning speed of the scanning lamp (2) and mirror (3) by a DC servo motor, which will be described later, and the horizontal magnification is determined by the lens (7) and mirror (4), The magnification is changed by moving the position (5) to be variable using a stepping motor, which will be described later.

(9) is the paper cassette, the feeder is the feeder, and (11) is the registration gate that temporarily waits the paper. The paper to be used is fed from the paper cassette (9) by the feeder (1o), and the misfeed sensor (12) ) and is temporarily waited at the registration gate αD.

The width of the paper used is detected by a paper size detection means (not shown). The registration gate 011 is configured to be lowered by turning on a solenoid after a predetermined period of time from the start of scanning of the scanning lamp (2), and when the registration gate α1) is lowered, the paper is It is made to travel to a transfer section near the photosensitive drum (8).

Around the photoreceptor drum (8), there is a charge corotron α.
(8) Developing device 041 for developing the latent image on the photosensitive drum (8) with toner. A transfer corotron (151) and a cleaner blade (161) are provided.As mentioned above, the latent image formed on the photoreceptor drum (8) during scanning is visualized as a toner image by the developer αa, and this is transferred to the photoreceptor. As the body drum (8) rotates in the direction of arrow a, it is moved to the transfer corotron 05), and when the registration game H1l is lowered, the paper waiting there is also transferred to the transfer corotron (15). ), and the toner becomes on the photoreceptor drum (8) that is aligned with the paper, but around the photoreceptor drum (8), there is also a developer at a position in front of the developer 0Φ. The photoreceptor drum (8
A side erase lamp (lη) is arranged as a light source for erasing unnecessary image areas on ).

The paper on which the toner image has been transferred is conveyed to the fixing device (19) via the transport belt 081, the toner image on the paper is fixed by the fixing device α, and the paper is ejected from the copying machine. The photosensitive drum (8) further rotates in the direction of arrow a, and in preparation for the next copy, the toner is scraped off from the surface by pulling the cleaner blade (1). )) is a lamp home sensor, (F) is a scanning end sensor, (A) is a lens sensor, and (C) is a paper ejection sensor.

As shown in FIG. 2, the side erase lamp (1η) described above is composed of lamp portions (c), (c), and (c) arranged along the drum axis direction of the photoreceptor drum (8). In the case shown, if the center registration method is used to place the original on the manuscript table (1), the center registration method is used to place the original on the manuscript table (1). This is an example of the arrangement when the center of the paper is set to always pass through the center of the photoreceptor drum (8), and the lamp parts (C), (C), and (C) are for paper B4 and A4.
, A5, and are mounted on both the left and right sides at positions corresponding to A5, respectively, and can be independently controlled to light up so as to erase unnecessary portions at both ends of the latent image. Furthermore, in this example, the maximum paper that can be copied is A8, and the width of the document table (1) is also 83, or 297 [:wn
:l is set.

The side erase lamp (17) shown in FIG. side erase lamps (1) corresponding to the width of the paper.
η is lit, and in the case of reduced copying, the number of side erase lamps αη is lit in accordance with the product of the width of the document table (1) and the reduction ratio, or the width of the paper, whichever is smaller. controlled so that

Figure 8 shows the components of a microcomputer for performing such control. (a) is the CPU, (b) is a programmable counter, (b) is a lens motor, (g) is a lamp scanning motor, and each of these motors is As mentioned above, (c) and (to) are composed of a stepping motor and a DC servo motor. 01) is the input/output controller, 0 old RAMX (3
1 is a ROM, and this ROM (3) determines whether it is a full size copy or an enlarged copy, and if the determination result is YES, a side erase lamp a is activated depending on the width of the paper being traveled.
If η is turned on and a NO judgment result is obtained, in other words, in the case of a reduced copy, the paper size is compared with the value obtained by multiplying the width of the document glass (1) by the reduction ratio, and the side erase lamp ( 1η is pre-stored with a program that lights up to erase the latent image up to the width corresponding to the smaller value.The CPU @ executes the program based on the information on the paper width and the reduction ratio, and Erase lamp (1
Control η. In FIG. 3, (b) is an address data bus, and (to) is a crystal oscillator.

Next, with reference also to FIG. 4, the lighting control of the side erase lamp αη in the case of one-time normal-size and enlargement copying, and one-time reduction copying will be explained in more detail.

First, FIG. 4 is a diagram that comprehensively shows the relationship between paper size and reduction ratio. The vertical axis (yl) is the width of the latent image of the original document formed on the photosensitive drum (8), and the horizontal axis (X) is the reduction ratio. For example, when the reduction ratio is 0.5 (50%), The latent image width of an A8 document is equal to the width of A5 paper, 148.5 [gourd]. Therefore, in the case of reduction of 50 inches, the charge is placed on the photoreceptor drum (8) outside the width of 1485 [■]. The charged area is illuminated by a side erase lamp (171) to lower the charge. If this is not done, toner will adhere to the charged area by the developer αa, resulting in wasted toner consumption. Furthermore, if the paper is a large paper such as A8, this toner will be transferred to the paper by the transfer corotron 05), resulting in solid black on both sides of the paper, resulting in a dirty copy.On the contrary, if the paper is small such as A5, the toner will be transferred to the paper In the case of paper, the toner image is not transferred to the paper by the transfer corotron α5) and is collected by the cleaner blade αe, but the toner image exceeds the cleaning capacity of the cleaner blade αe. In some cases, offset development may appear on the next copy or cause dirt inside the machine. Therefore, side erase lamp u'? ) lamp part (c), (c), (
The lighting control conditions (c) are set as shown below to perform control to lower the charge on the photosensitive drum (8) so that the optimum erasing width is always achieved.

That is, in FIG. 4, if we take as an example a case where a 85-inch reduced copy is to be made on A4 paper, the width 297 (m+n) of the A3 document table (1) will not fit on the photoreceptor drum (8). It is projected as a latent image of 297x 0.85 = 252 (mm:].On the other hand, the moving paper A4 is projected as a latent image of zlo(+
mn) width, so an image with a width of 252-210=42 (tianth) will not be transferred to the paper but will be collected by the cleaner blade (16). Turn on (c) and paper width is 210Cwn:]
Control is performed to erase latent images and charges other than the above. Similarly, in the case of enlarged copying, if the latent image width is larger than the width of the paper, the side erase lamp aη is pressed up to the width of the paper.
Control it so that it disappears.

In Fig. 4, the shaded area on the right side of the straight line OQ is
When using A4 size paper, this indicates the range of the aspect ratio in which an image protrudes from the paper.If the aspect ratio is from 0707 to 15, which falls within the shaded range, In other words, the latent image at the edge of the A4 paper is controlled to be erased up to the width of 210 cm:).

As a result, the lighting control conditions for the side erase lamp (17) are as follows.

(1) In the case of full size and enlarged copying, the side erase lamp 0η is turned on up to the width of the traveling paper.

(2) In the case of reduced copying, the following determination is made.

That is, the paper size is compared with the value obtained by multiplying the width of the document table (1) by the aspect ratio. And side erase lamp 07
1 lights up so as to erase the latent image to a width corresponding to whichever is smaller.

In this way, it is possible to turn on the optimal number of side erase lamps 0η to prevent unnecessary toner images from being developed by considering the width of the paper and the reduction ratio in combination, so that the optimal erasing width can always be achieved. This makes it possible to reliably prevent the wasteful consumption of toner, the generation of smeared copies with solid black edges, the offset phenomenon, and the problems of dirt inside the machine.

Moreover, since the paper width is compared with the value obtained by multiplying the aspect ratio by the width of the document table (1), it can be carried out regardless of the number of steps of the reduction ratio, and the method of the above embodiment can be carried out. When a side erase lamp t17) consisting of a plurality of lamps is used as a light source, the number of divisions may be set to any number. Furthermore, in the case of a copying machine with a zoom magnification, for example, a copying machine with a function that allows setting the magnification in 1% increments, this has not been possible in the past.
The control as described above can be applied even to a copying machine having such a zoom function, and is particularly suitable for use in erasing unnecessary image areas in such cases.

〔Effect of the invention〕

As described above, this invention makes it possible to obtain the optimum erasing width according to the paper width and magnification, so it is possible to reliably prevent unnecessary toner images from being developed, and reduce toner consumption due to this. It has features such as being able to prevent the occurrence of increased dirt inside the machine.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the inside of a copying machine to which an embodiment of the present invention is applied, FIG. 2 is an explanatory diagram showing an example of the relationship between the side erase lamp and the width and magnification of the applicable paper, and FIG. 8 is a micro FIG. 4, a configuration diagram of the computer, is a diagram showing the relationship between the vertical magnification ratio and the width of the latent image on the photosensitive drum. Description of symbols (11...Original table (8)...Photosensitive drum (1η...Side erase lamp (c)...
...CPU Patent applicant: Fuji Xerox Co., Ltd. Agent: Tomohiro Nakamura, Patent attorney: Katsuo Naruse Figure 1 Figure 2

Claims (1)

[Claims] This is a method of erasing unnecessary image areas on photosensitive material by controlling the erase light source, and in the case of full-size copies, the width of the paper is used as the reference, and in the case of reduced copies, the ratio of the width of the document glass to the magnification is used as the reference. A method for erasing an unnecessary image area of a photosensitive material, characterized in that the erasing width is set based on the product of , or the paper width, whichever is smaller.