JP2662422B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is an image forming apparatus that cleans an image carrier by contacting the image carrier and reciprocates the image carrier in a longitudinal direction of the image carrier to clean the image carrier. Related to the device.

[Conventional technology]

Conventionally, on the surface of an image carrier on which a transferable toner image has been formed,
In a known image forming apparatus, a sheet-shaped transfer material mainly made of paper is brought into contact with a toner image, and the toner image is electrostatically transferred onto the transfer material, and then the process of separating the transfer material from the image carrier is repeated. It is necessary to remove the residual toner which does not contribute to the transfer and remains on the surface of the image carrier even after the transfer material is separated.

For this reason, a number of means have been conventionally proposed as a means for removing the residual toner, but one edge of a plate-shaped cleaning blade made of an elastic material such as urethane rubber is pressed against the image carrier to remove the residual toner. It is well known that the scraper is widely used because it has a simple structure, is compact, and has an excellent toner removing function.

However, such a cleaning means also causes the toner stored in the edge portion to solidify without falling down and lift the blade to cause a deterioration in the cleaning means function, and this toner may cause the toner to fall on the image carrier. It is unavoidable to cause adhesion and fusion to cause deterioration of image quality and various inconveniences.

Further, as a means for removing deposits on the surface of the photoreceptor, an elastic roller or the like in which a sponge layer is coated with an elastic rubber is known. The elastic roller is effective for removing products, paper dust, and the like caused by corona discharge of the charger, which causes image flow particularly under high humidity. However, since the elastic roller is strongly pressed against the surface of the photoreceptor and rubs the surface of the photoreceptor, streaking occurs in the circumferential direction of the photoreceptor, causing a streak on a copy image, which may also cause image deterioration. .

In order to avoid such inconveniences, there has been proposed a configuration in which the cleaning blade and the elastic roller are reciprocated with an appropriate stroke in the longitudinal direction thereof. According to this method, a kind of stimulus is given to the edge of the cleaning blade to prevent the toner from being accumulated or the foreign matter from adhering. Further, in the case of the elastic roller, the effect is obtained in preventing the stripe from being removed in the circumferential direction of the photoconductor. For example, Japanese Patent Application Laid-Open No. Sho 62-105181 discloses that a cleaning blade is reciprocated in the longitudinal direction of an image carrier.

However, when such a cleaning blade or an elastic roller is reciprocated, it is inevitable that the photosensitive member or the like is vibrated particularly when the direction of movement is reversed, and the image quality may be degraded due to displacement or the like. In particular, when a latent image is formed by scanning the surface of a photoreceptor with a small spot of laser light, such as a laser printer, a digital copying machine, or a digital color copying machine, the position of the spot is blurred. In many cases, the image is disturbed and the image quality is deteriorated. In particular, a cleaning blade is used in a copying machine in which each color is developed several times on a photoconductor like a full-color copying machine, and each time a toner image of each color is transferred to a transfer material held on a transfer material carrier (hereinafter referred to as a transfer drum). In addition, image quality was deteriorated due to transfer deviation due to vibration caused by reciprocating motion of the elastic roller.

[Object of the invention]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has been made in view of the above-described circumstances. Accordingly, it is possible to maintain the advantages of reciprocating a cleaning unit with respect to an image carrier, and to prevent the image carrier from vibrating as much as possible. It is intended to provide a device.

Further, the present invention provides an image forming apparatus which obtains a good image without image blur by preventing the occurrence of the vibration of the image carrier as described above, and in particular, makes effective use of the characteristics of an apparatus capable of obtaining a high precision image. The purpose is to provide.

[Configuration of the invention]

In order to achieve the above object, the present invention provides a latent image forming means for forming a latent image on a moving image carrier, a current means for developing a latent image formed by the latent image forming means, and a developing means for forming a latent image on the image carrier. Transfer means for transferring the developed image to a transfer material, cleaning means for contacting the image carrier and cleaning the developer remaining on the image carrier after transfer, and reciprocating the cleaning means in the image carrier length direction. In an image forming apparatus having a reciprocating means and a control means for controlling the operation of the reciprocating means, the control means controls the image holding of the cleaning means by the reciprocating means while forming a latent image on the image carrier. The moving speed of the reciprocating movement with respect to the body is set lower than when no latent image is formed on the image carrier, or the stroke is increased, or the movement of the cleaning unit is stopped. It is intended.

Further, the control means of the present invention further comprises, while forming a latent image on the image carrier and developing the latent image, controlling the reciprocating movement speed of the cleaning means with respect to the image carrier by the reciprocating means. The latent image is formed on the carrier, and the latent image is made lower than when the latent image is not developed, the stroke is increased, or the movement of the cleaning unit is stopped.

Further, the control means of the present invention forms a latent image on the image carrier, develops the latent image, and further transfers the developed image to the transfer material. The moving speed of the reciprocating movement with respect to the carrier is set to be lower than when the latent image is formed on the image carrier and the latent image is developed, and the developed image is not transferred to the transfer material, or the stroke is increased. Or stop the movement of the cleaning means.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 3 is a schematic side view showing a laser beam printer using an electrostatic transfer process suitable for applying the present invention.

The surface photosensitive layer of the image carrier 1 extending in the direction perpendicular to the paper and rotating in the direction of the arrow is uniformly charged by the primary charger 2. The charged image carrier 1 is provided with a laser beam 3 converted from image information into an electric signal and modulated accordingly.
Is irradiated with light from a laser beam scanner to form an electrostatic latent image. Here, an LED array, a liquid crystal shutter array, or the like may be used for light irradiation.

Toner is supplied to the latent image by a developing device 4, and the latent image is visualized to form a toner image.
After being transferred to the transfer material P conveyed at the same timing as the toner image by the action of the transfer separation charger 6, the transfer material is separated from the image carrier, and further transferred along the conveyance path 8 to the next step. It shall be transported.

In such a case, the cleaning blade 9 in the cleaning device 7 arranged at the position after the transfer reciprocates in the axial direction (perpendicular to the paper surface) while being pressed against the image carrier 1. I have.

FIG. 2 shows an example of a means for reciprocating the blade. A cleaning blade 9 in a cleaning device 7 indicated by a chain line has an axis which is deflected leftward by a spring 11 in the device. Supported by 10.

The left end of the shaft 10 is in contact with a cam 12, which is driven by a motor 13 controlled by a control circuit 14 as a control means to reciprocate the shaft 10, and thus the blade 9.

It is assumed that the above-described apparatus operates each unit as shown in the sequence of FIG.

FIG. 1 shows a case where two sheets of image formation are executed in succession. The reciprocation of the blade is performed only during the pre-rotation and post-rotation of the apparatus, and is stopped during the image formation. Here, the time of image formation refers to all steps of latent image formation, development, and transfer.

In the experiment, an amorphous silicon photoreceptor of 80φ was used as the image carrier, the peripheral speed was 180 mm / sec, and the blade pressure was 2
0gr / cm, the reciprocating stroke (moving distance) is 2mm,
The test was performed at a speed of 3 mm / sec.

By performing such an operation, it was possible to prevent the resolution from lowering due to the reciprocating motion of the blade and the uneven pitch in the halftone portion.

FIG. 4 shows a cleaning device 7 in which a cleaning blade 9 and an elastic roller 10 disposed on the upstream side in the moving direction of the photoconductor 1 are pressed against the photoconductor 1 by the blade 9. The elastic roller 10 is configured to rotate in the direction of the arrow and reciprocate in the axial direction, similarly to the blade shown in the previous embodiment. The elastic roller 10 is effective for removing corona products, paper dust, and the like by a corona discharger, which causes image flow particularly under high humidity. FIG. 5 shows a sequence of the reciprocating motion of the elastic roller 10. FIG. 5 shows a case where one image is formed. The reciprocation of the elastic roller 10 is performed only during the pre-rotation and post-rotation of the apparatus, and is performed during the image formation (latent image formation, development, and transfer). All processes).

In the experiment, an A-Si photoreceptor of 80φ was used as the photoreceptor, and the peripheral speed was 180 mm / sec. The elastic roller had an outer diameter of 18φ, and was pressed against the photoconductor at a pressure of 60 g / cm per unit length of the roller, and rotated at a peripheral speed of about 160 mm / sec. The reciprocating motion of the elastic roller was a stroke of 2 mm and a speed of 0.5 mm / sec. The configuration of the roller was such that a sponge layer was formed on a cored bar 6φ and the surface layer was coated with urethane rubber having a hardness of 50 mm (JISA).

By performing such an operation, it is possible to prevent a decrease in resolution due to reciprocation of the blade, a pitch unevenness in a halftone portion, a blur, and the like.

Here, the blade 9 cleans the image carrier.
And both the elastic roller 10 and the elastic roller 10
Can be used alone.

Referring to FIG. 1 and FIG.
Alternatively, the reciprocating motion of the elastic roller 10 is resumed, but if transfer deviation or the like does not occur and there is no adverse effect on the image quality, the reciprocating motion may be operated after the development is completed, or if there is no pre-image by development, the latent image It is also possible to operate the reciprocating motion after the formation is completed. FIG. 6 shows an example in which the operation is disclosed after the completion of the developing process.

Also, as shown in FIG. 1, the blade 9 is stopped between the image formation on the photoconductor at the time of continuous copying and the next image formation. As shown, the blade 9 or the elastic roller 10 may be reciprocated after the development of the first sheet is completed and until the formation of the second latent image is started.

In the embodiment described above, when the image quality is adversely affected,
The reciprocation of the blade 9 or the elastic roller 10 was stopped,
If the cleaning function is thereby reduced, the reciprocating speed may be slowed instead of being continuously operated and stopped. According to experiments, the speed for forming non-image quality was 3 mm / se
c) Good results were obtained by setting the speed at the time of image quality formation to 1 mm / sec.

Further, instead of stopping the reciprocating motion of the blade 9 or the elastic roller 10 as described above, the stroke at the time of the image is made longer than the stroke at the time of the non-image, and the number of reversal of the reciprocating motion direction is reduced and given to the apparatus at the time of the reversal. The frequency may be reduced. In this manner, the stroke can be easily changed by, for example, converting the cam 12 to a cam 12 'having a different inclined portion from the cam 12 by the switching means as shown in FIG.

Furthermore, in order to effectively remove foreign matter adhering to the blade edge, the reciprocating speed of the blade is large and it is better to increase the number of reciprocations, so that during image formation, the speed is reduced to increase the reciprocating stroke, It is preferable to reduce the number of reciprocating movements and increase the number of reciprocating movements at high speed and with a small stroke during non-image formation.

The alteration of the sequence described above can be easily performed by changing the number of rotations of the motor by controlling the signal output of the control circuit 14 within the range of the well-known control means even in the means shown in FIG. It is obvious that it can be done.

Further, in the above-described embodiment, the pressing force of the elastic roller 10 on the photoconductor may be weaker at the time of image formation than at the time of non-image formation.

FIG. 8 is a schematic diagram when the present invention is applied to a full-color copying machine. A charger 2 and an exposure device 3 are arranged around the photoreceptor 1, and an electrostatic latent image is formed on the photoreceptor by an electrophotographic process as in the above embodiment. The latent image is developed by a developing device 4 composed of a plurality of developing units 4Y (yellow), 4M (magenta), 4C (cyan), and 4B (black), each having a developer of a different color. It is visualized.

On the other hand, a transfer sheet P such as a transfer sheet is supplied to a transfer drum 18 by a sheet feeding means 17. The transfer material supported by the transfer drum transfers a visualized toner image by a transfer charger 19. At this time, as in the case where the first color is developed on the photoreceptor, the toner image is transferred to the transfer material, and then the second color is developed and transferred, the full color copy is performed four times ( 4
A process called development / transfer of color components) is performed.

Next, the transfer material is weakened by a static eliminator 20 to reduce the attraction force to the transfer drum 18, is separated from the transfer drum 18 by the separation claws 21, and the toner image is heated by the fixing device 16.

The photoreceptor is cleaned by the cleaning blade 9 of the cleaner 7 for each development of one color. The transfer drum 18 is configured so that scattered toner and the like are cleaned by the brush 15.

As described above, in the case of full-color copying, development and transfer are repeated for each color, and a copy is completed by superimposing four colors. Therefore, it is necessary to avoid image quality deterioration due to blurring or the like in a single color machine, and furthermore, pre-shift or mis-transfer to a transfer material as much as possible.

Also in this case, the image quality can be maintained by the cleaning blade 9 in the same sequence for each color as in the above-described embodiment. Of course, the same applies to the copying machine having an elastic roller in addition to the cleaning blade 9. If necessary, the reciprocating motion of the cleaning blade or the elastic roller may be stopped or the speed may be reduced or the stroke may be lengthened until the transfer material is separated from the transfer drum.

Although the digital machine in which the latent image is formed by laser light has been described, it goes without saying that the same applies to an analog machine in which a lamp is used.

In the above embodiments, amorphous silicon is used as the image carrier, but amorphous silicon has excellent durability and can be used for a long time. As described above, since amorphous silicon is used for a long period of time, it is suitable for the present invention in which the blade or the elastic roller is reciprocated to improve the cleaning property. However, not limited thereto, ZnO, CdS,
A photoreceptor such as Se or OPC may be used, or an insulating drum having no photoconductive layer may be used.

Further, in this embodiment, a blade and a roller are used as a cleaning unit of the image carrier, but a brush may be applied.

Further, in this embodiment, the reciprocating motion of the cleaning blade or the elastic roller is stopped or the speed is reduced during image formation. May be reciprocated only when necessary or the speed may be increased by stopping or reducing the speed.

〔The invention's effect〕

As described above, according to the present invention, the cleaning means can be reciprocated with respect to the image carrier to clean it satisfactorily, and the occurrence of the vibration of the image carrier can be prevented as much as possible. Further, according to the present invention, it is possible to obtain a good image without image blur by preventing occurrence of vibration of the image carrier.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1, FIG. 5, FIG. 6, and FIG. 7 are diagrams showing a timing sequence according to an embodiment of the present invention, and FIG. FIG. 3 is a schematic diagram showing an example of a configuration for controlling reciprocation, FIG. 3 is a schematic diagram showing a laser beam printer to which the present invention is applied, and FIG. 4 is another embodiment of the present invention. FIG. 8 is a schematic view showing an image forming apparatus having the same, and FIG. 8 is a schematic view showing a hel collar to which the present invention is applied. In the figure, 1 ... image carrier, 9 ... cleaning blade, 10 ... elastic roller, 14 ... control means.

Claims (3)

(57) [Claims] A latent image forming means for forming a latent image on a moving image carrier; a developing means for developing the latent image formed by the latent image forming means; and a developing means for developing the latent image formed on the image carrier. Transfer means for transferring to a transfer material, cleaning means for contacting the image carrier and cleaning the developer remaining on the image carrier after transfer, and reciprocating means for reciprocating the cleaning means in the image carrier length direction. A control unit for controlling the operation of the reciprocating unit, wherein the control unit reciprocates the cleaning unit with respect to the image carrier by the reciprocating unit while forming a latent image on the image carrier. The movement speed of the movement is made lower than when no latent image is formed on the image carrier, the stroke is increased, or the movement of the cleaning means is stopped. An image forming apparatus. A latent image forming means for forming a latent image on a moving image carrier, a developing means for developing the latent image formed by the latent image forming means, and a developing means for developing the latent image formed on the image carrier. Transfer means for transferring to a transfer material, cleaning means for contacting the image carrier and cleaning the developer remaining on the image carrier after transfer, and reciprocating means for reciprocating the cleaning means in the image carrier length direction. A control unit for controlling the operation of the reciprocating unit, wherein the control unit forms a latent image on the image carrier and develops the latent image by using the cleaning unit by the reciprocating unit. Moving the reciprocating movement speed of the reciprocating motion with respect to the image carrier is lower than when a latent image is formed on the image carrier and the latent image is not developed, or the stroke is increased, or the cleaning speed is increased. An image forming apparatus for stopping the movement of the imaging means. 3. A latent image forming means for forming a latent image on a moving image carrier, a developing means for developing the latent image formed by the latent image forming means, and a developing means for developing the latent image formed on the image carrier. Transfer means for transferring to a transfer material, cleaning means for contacting the image carrier and cleaning the developer remaining on the image carrier after transfer, and reciprocating means for reciprocating the cleaning means in the image carrier length direction. A control unit for controlling the operation of the reciprocating unit, wherein the control unit forms a latent image on the image carrier, develops the latent image, and further transfers the developed image to a transfer material. In the meantime, the moving speed of the reciprocating movement of the cleaning means with respect to the image carrier by the reciprocating means is controlled by forming a latent image on the image carrier, developing the latent image, and further transferring the developed image to a transfer material. Lower than when not Or to increase the stroke,
Alternatively, the image forming apparatus stops the movement of the cleaning unit.