JPS6014257A - Copying device - Google Patents

Abstract

PURPOSE:To erase unnecessary electric charge without erasing the necessary electric charge image within the non-image region on a photosensitive body by forming the apertures of an exposing device in such a way that at least a part of the light image formed on the photosensitive body by the exposing device is not uniform in the generator direction of the photosensitive body. CONSTITUTION:Apertures 42a, 43a are provided in the part of an exposing device 40 facing a photosensitive drum 5 and an aperture 44a is provided on the side face, by which the light image of an erasing lamp 41 onto the drum 5, that is, the irradiation region thereof is the regions 42b, 43b, 44b shown by diagonal lines. The region 44b is the part corresponding to the position of a batch image region with respect to the axial direction of the drum 5 and even if all the lamps 41 are turned off simultaneously at the same timing, the unnecessary electric charge is erased without erasing the batch image region.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an improvement in an exposure device for erasing unnecessary charges in non-image areas of charges applied to a photoreceptor in a copying apparatus in an industrial field.

Prior Art Conventionally, in order to keep the density of a copied image constant, an image for toner density control is formed on a non-image area on a photoconductor, and the image density is detected based on information about light reflected from the image. A device that controls toner density based on the value has been proposed and put into practical use. The proposed device will be explained with reference to FIGS. 1 and 2. FIG. 1 is a schematic cutaway diagram of an electrophotographic copying machine. 1 is the copying machine main body, 3 is the document holding member (platen cover), and the document 2 is placed on the stacking table glass 4 and rotates in the direction of the arrow o5u,
It is uniformly charged by the charging electrode 6.

An optical system is constituted by a first mirror unit 8 to [2 mirror unit 9, a lens 10s, and a third mirror 11] having an exposure lamp 7, and when the second mirror unit 9 moves in the arrow direction, the first mirror The unit 8 moves at twice the speed in the direction of the arrow to expose and scan l1iKI2, and irradiates the reflected light from the original 2 onto the photosensitive drum 5 through the lens 101, the third mirror 11, and the slit 12. Forming an electrostatic latent image Before exposure scanning of the original 2, a reference image 13 provided in the copying machine body 1 is scanned to form an electrostatic latent image on the photoreceptor drum 5 due to light reflected from the reference image 13. An image is formed. Subsequently, an electrostatic latent image corresponding to the original 4112 is a replenishment portion. On the other hand, the copy paper 17 in the paper feed cassette 16 is sent out by the first paper feed roller 18 and wc
l1iK on the photoreceptor drum 5 by the two paper feed rollers 19.
0 which is synchronized with the draft area and sent onto the photosensitive drum 5.
The copy paper onto which the toner image has been transferred by applying a transfer pole is separated by a separation pole 21 and transported to a fixing section n by a conveyor belt 22.
transported to. The copy paper 17 is attached to the fixing roller Z in the fixing section n.
3A and the pressure roller 23B, and the paper is discharged to the paper discharge tray section via the paper discharge roller.

On the other hand, a toner concentration control @ image (hereinafter referred to as a batch image) 27 obtained from the reference image 13 remains on the photoreceptor drum after transfer, and a reflective photo sensor is used to detect the reflection density of this batch image n. C) 26 (hereinafter referred to as sensor).

Diagram 2 is a schematic diagram showing the state of the photosensitive drum 5 and the sensor after transfer. The sensor irradiates the patch image I with its light emitting element 26A and receives the reflected light with its light receiving element 26B. Based on the output from the light receiving element 26B, l.
It controls the supply of toner from the toner replenishing section 15 to the developer 514 and controls the density of the copied image. Thereafter, the photosensitive drum 5 is cleaned by the removing electrode side and the cleaning unit, and one predetermined copying process is completed.

In the case of a copying machine that controls toner density by forming a patch image on a photoreceptor as described above, the positional relationship between the effective image area on the photoreceptor and the batch image area is as shown in FIG. 3. In FIG. 3(4), the photoreceptor (9) shows a developed view of the surface of the photoreceptor drum, and the photoreceptor 30 moves in the direction of the arrow. 31 is an effective image area for forming an image of a document, and 27 is a batch image area corresponding to the reference image 13. By the way, the pursuit of making copying machines more compact inevitably leads to
), unnecessary images may be formed due to the shadow of the lifting unit inside the copying machine main body, the shadow caused by the slope or step of the reference image mounting plate, etc. Such an unnecessary image 3
2. There is no actual problem during transfer, but 1. If unnecessary images are developed, toner will be wasted. In addition, such wasted toner adhering to the photoreceptor also increases the burden on the cleaning member.Therefore, in order to erase such unnecessary images, a method using an erasing lamp has been conventionally used. It is being FIG. 4C is a schematic diagram showing the positional relationship between the erase lamp and the vicinity of the photoreceptor.

33 C is an exposure device equipped with an erasing lamp, and the opening facing the photoreceptor drum 5 is dark. Although not shown in FIG. 4, the slit 12 for irradiating the photoreceptor with the light reflected from the original shown in FIG.
C. The exposure device may be located either before or after the exposure device with respect to the rotational direction of the sensing element drum 50. If a 7J:8 element device is used like this, 1 unnecessary images 32 and up to the batch image area n will be erased. This makes it impossible to perform proper toner density control. Therefore, the timing of turning off the erasing lamp is as shown in FIG. 3 (8).
I try to keep it between a and a. However, copying machines equipped with functions such as reduction and enlargement are now in widespread use, and when one reduction is performed, the area narrows to area b shown in Figure 3, and it is necessary to speed up the rise and fall of the high-voltage transformer and erase lamp. There is 0 and the extinguisher lamp is on.

High precision is also required for the OFF timing6-. Even under such circumstances, the unnecessary image 32 must be completely erased and the batch image area 27 must be prevented from being erased. Therefore, the OF of the erase lamp shown in FIG.
It is better to bring the F timing as close as possible to unnecessary ff132. However, as a result, a problem arises in that an unnecessary dense mixture is developed due to variations in one part or the like. As a countermeasure against this problem, conventional erase lamps are used in which IJDs are arranged in the direction of the generatrix of a plurality of photoreceptor drums.
A method of increasing the timing has been considered, but this method has drawbacks such as complicated control and high cost.

OBJECTS OF THE INVENTION In order to achieve the above object, it is to provide a copying apparatus that solves the above drawbacks with a very simple structure. In a copying apparatus equipped with an exposure device for erasing unnecessary electric charge generated by one exposure, at least a part of the optical image formed on the photoreceptor by the exposure device is aligned with respect to the generatrix direction of the photoreceptor. 1. By forming the opening of the exposure device in such a manner that the exposure device does not disturb the image, unnecessary charges can be reliably erased without erasing necessary charge images in the non-image area on the photoreceptor. The present invention provides a copying apparatus characterized by The formed charge image is a charge image for controlling toner density.O further characterized in that a part of the opening is provided on a side surface of the exposure device so that the width of the opening is different from the width of the feature. shall be.

An embodiment of the present invention is shown in FIG. 5. FIG. 5 is a schematic diagram showing the relationship between an exposure device 40 and a photosensitive drum 5, which is an erase lamp 41. Erase lamp 41
Various types of lamps such as tungsten lamps, LEDs, and neon lamps can be used. Openings 421 to 43m are provided in a portion of the exposure device 40 facing the photoreceptor drum 5. Further, an opening 441L is provided on the first side surface of the exposure device at a portion corresponding to the position of the batch image area in the axial direction of the photosensitive drum 5. According to this configuration, the image of the erasing lamp 410 on the photoreceptor drum 5, that is, the irradiation area is indicated by diagonal lines 42b, 43b, 44.
Therefore, even if the OFF timing of the erasing lamp 41 is set for all lamps at the same time, the 6th v value on one sensing element body is 0! As shown by the dashed line C in J, the irradiation light from the vanishing lamp is turned off. Note that the position of the opening 44m can be changed depending on the design.Also, in the above embodiment, an exposure device equipped with an erasing lamp has been described, but in the present invention, the erasing lamp is provided in a separate location, and the exposure device is equipped with an erasing lamp. Of course, the present invention can also be applied to an exposure apparatus in which only a slit with an opening is installed near the drum. In addition, although the above explanation has been about a copying machine that forms batch images, the present invention is limited to batch images, and is capable of partially erasing images on one photoreceptor. It can be applied to anything.

FIG. 7 shows another embodiment in which only a portion of the opening 52m of the exposure unit group corresponding to the batch image area is formed as shown at 53b in the figure. The irradiation area on the photoreceptor 5 is now shown as 52b indicated by diagonal lines, and 53
The submolecule corresponding to a is rs3b. That is, by making part of the width of the opening different from the width of the other part, the same effect as the embodiment shown in FIG. 5 can be obtained. However, in this case, if the light intensity of the erase lamps is all the same, the irradiated area will be different between the portions 53b and 52b, and the degree of fatigue of the photoreceptor 5 will be different, which may cause an unfavorable situation in image formation. . However, even in such a case, the problem can be easily solved by changing the light intensity of the erasing lamp depending on the aperture, or changing the height of the erasing lamp from the photoreceptor depending on the aperture.

Note that the shape of the opening is not limited to this, and may of course be an arcuate shape or the like.

10- Effects of the Invention The present invention has a simple configuration as described above, and by turning on or turning off all the erasing lamps at the same time, unnecessary electrostatic latent scratches on the photoreceptor can be surely erased and the desired image can be formed. It has the effect of being able to prevent it from being erased.

[Brief explanation of the drawing]

Figure 1 is a schematic cross-sectional view of a copying machine with a reference image. Figure 82 is a schematic diagram showing the relationship between the photoreceptor drum and the sensor. Figure 3 is a diagram showing the image area on the photoreceptor and the OFF timing of the erase lamp. Figure 4 is a schematic diagram showing the positional relationship between a conventional exposure device and the area around the photoreceptor drum %fa5 Figure shows an exposure device according to the invention Example 1 FIG. 1 shows the OFF timing of the irradiation light by the erasing lamp on the body. FIG. 7 shows another embodiment of the present invention.
3...Reference image A...Sensor is off...Light emitting element 26B...Light receiving element I...Toner density control image (patch image) 51...Effective image area 32...Unnecessary Image, 40.50...Exposure device 34, 41, 51...Erasing lamp 42m
+ 43a + 44a, 52a r 53m...
・Openings 42b, 43b, 44b, 52b
, 53b...Representative of the irradiation area by the erasing lamp on the photoconductor drum Yoshimi Kuwahara No. 7121 4〈 □ > 1 So\/Do/2202

Claims (4)

[Claims] (1) In a copying machine equipped with an exposure device that erases unnecessary charges applied to a non-image area on a photoconductor by exposure, at least one of the optical images formed on the photoconductor by the exposure device By forming the opening of the exposure device so that the area is not uniform with respect to the generatrix direction of the photoreceptor, necessary charge images in non-image areas on the photoreceptor are not erased (unnecessary charge images are removed). A copying device characterized in that it is capable of reliably erasing electrical charges. (2) Necessary charge gI in the non-image area on the photoreceptor
Claim 1 is characterized in that the image is a charge image for controlling toner density formed in a non-image area on a recording sensitive material in order to maintain a constant density of a copied image. Copying device as described. (3) The copying apparatus according to claim 1 or 2, wherein a part of the opening is provided on a side surface of the exposure device. (4) Claim M (1) or (4) characterized in that one part of the opening provided in the part of the exposure device facing the photoreceptor is made different in width from the other part. The copying device according to item 2.