JP2004252030A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively remove matter sticking on the surface of a photoreceptor by using a reduced amount of toner supplied to a cleaning blade, in an image forming apparatus that cleans the surface of the photoreceptor in such a manner that, when paper is unfed, the toner for cleaning the surface of the photoreceptor is supplied to a cleaning device by attaching the cleaning toner to the surface of the photoreceptor, and the attached cleaning toner is scraped and recovered by a cleaning blade. <P>SOLUTION: A fed-paper size detection means for detecting the size of fed-paper is additionally provided. Thereby the size of transfer paper fed immediately before is detected by a fed-paper size detection means. A larger amount of cleaning toner is attached to photoreceptor parts 91 corresponding to both edge areas of the transfer paper in the axial direction of the photoreceptor than to a photoreceptor part 92 corresponding to the middle area of the transfer paper. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electronic copier or a printer, and more particularly, to use a cleaning action of a toner to scrape off a deposit on the surface of a photoreceptor, thereby forming filming or photoreceptor generated on the surface of the photoreceptor. The present invention relates to an image forming apparatus for preventing deterioration of a body surface.
[0002]
[Prior art]
So-called filming, in which toner components and paper powder adhere to the surface of the photoreceptor, has been a problem. When filming occurs on the surface of the photoreceptor, the charged potential of that portion drops, so that toner also adheres to portions other than the latent image on the surface of the photoreceptor, and the background portion of the transfer paper becomes dark.
[0003]
Various proposals have been made so far to prevent such filming. For example, in Patent Document 1, when a predetermined amount of water or more and a predetermined number of images have been formed, a black band of toner is formed on a photoconductor, toner is supplied to a cleaning blade, and a toner polishing action is used. A technique has been proposed in which a cleaning blade is used to scrape off deposits on the surface of the photoreceptor.
[0004]
[Patent Document 1]
JP-A-2000-181321 (
~
(FIG. 21)
[0005]
[Problems to be solved by the invention]
By the way, from the viewpoint of effective use of resources, the use of recycled paper in image forming apparatuses such as copying machines and printers has been rapidly increasing in recent years. When recycled paper is used as the transfer member, talc components leak from both ends (that is, cut surfaces) of the recycled paper and adhere to the surface of the photoreceptor. For this reason, a large amount of deposits are attached to the photoconductor portions corresponding to both ends of the recycled paper, and filming is likely to occur in these portions.
[0006]
On the other hand, in the proposed technique, in order to form a toner band having the same width in the axial direction on the photoconductor, in order to sufficiently remove the extraneous matter attached to the photoconductor corresponding to both ends of the recycled paper, It is necessary to increase the toner supply amount to the cleaning blade by making the toner band thicker.
[0007]
However, the increase in the toner supply amount directly leads to an increase in the toner consumption amount, which is not preferable for the user. In addition, if toner is placed on the photoreceptor portion where the separation claw for separating the photoconductor and the transfer paper comes into contact, the separation claw becomes a medium, and the toner adheres to the transfer paper, causing a problem that the transfer paper becomes dirty. .
[0008]
The present invention has been made in view of such conventional problems, and has as its object to effectively remove deposits attached to the surface of a photoreceptor while reducing the amount of toner supplied to a cleaning blade. Things.
[0009]
Another object of the present invention is to prevent transfer paper from being stained by toner attached to a separation claw.
[0010]
[Means for Solving the Problems]
According to the present invention, a charging device for charging a photoreceptor surface, an exposure device for forming a latent image on the photoreceptor surface charged by the charging device, and the latent image on the photoreceptor surface with a toner containing an abrasive A developing device for developing the toner image, a transfer device for transferring a toner image formed on the surface of the photoreceptor formed by the development onto transfer paper, and a cleaning blade for scraping toner remaining on the photoreceptor surface after the transfer by the transfer device. A cleaning device having a paper feed detecting means for detecting a non-paper feed state, and in a non-paper feed state, attaching toner for cleaning the photoconductor surface to the photoconductor surface and supplying the cleaning device with the toner, In an image forming apparatus that cleans the surface of a photoreceptor by scraping and collecting the attached cleaning toner with the cleaning blade, a sheet feeding size for detecting a sheet feeding size is used. The paper size detection unit detects the size of the transfer paper that has been fed immediately before and detects the size of the transfer paper at both ends of the transfer paper rather than the photoconductor corresponding to the center in the photoconductor axial direction. An image forming apparatus is provided, in which a large amount of the cleaning toner adheres to the photosensitive member to clean the surface of the photosensitive member.
[0011]
Here, in order to remove the deposits on the photoreceptor surface while further reducing the toner supply amount to the cleaning blade, the amount of the cleaning toner adhering to the photoreceptor portions corresponding to the both ends is reduced by the central portion. Is preferably in the range of 1.1 to 10 times the adhesion amount of the photoreceptor portion corresponding to
[0012]
Further, in order to prevent transfer paper from being stained with toner by using the separation claw as a medium, it is desirable to prevent the cleaning toner from adhering to a portion of the photosensitive member that the separation claw contacts.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
The present inventor provides an image forming apparatus that supplies toner to a cleaning blade and uses a polishing action of the toner to scrape off the attached matter on the surface of the photoconductor with the cleaning blade. As a result of intensive studies to determine whether or not the attached matter on the surface can be effectively removed, it is possible to increase the amount of toner supplied to the portion of the photoreceptor surface where the attached matter is easily attached, while reducing the amount of toner supplied to the portion where the attached matter is not easily attached. At first glance, it seemed simple, but no one had yet implemented it, leading to the present invention.
[0014]
Hereinafter, an image forming apparatus of the present invention will be described with reference to the drawings. Note that the present invention is not limited to these embodiments. FIG. 1 is a schematic diagram illustrating an embodiment of an image forming apparatus according to the present invention. The surface of the photoconductor 1 is uniformly charged by the charging device 2. Next, an electrostatic latent image is formed on the surface of the photoconductor 1 by the exposure device 3. Then, toner is adhered to the electrostatic latent image by the developing device 4 to be visualized. The transfer device 5 transfers the toner image on the photoconductor 1 to the transfer paper P. Then, the transfer paper P is separated from the photoconductor 1 with the help of the separation claw 6. The toner image on the transfer paper P is thereafter fused and fixed on the transfer paper P by applying heat and pressure in a fixing device (not shown). On the other hand, the untransferred toner remaining on the photoconductor 1 is scraped off by the cleaning blade 71 in the cleaning device 7. Then, the charge on the surface of the photoconductor is removed by the charge removing device 8, and the next image is formed.
[0015]
In the image forming apparatus having such a configuration, when removing the deposit such as talc component attached to the surface of the photoconductor from the surface of the photoconductor, the cleaning toner is applied to the surface of the photoconductor when the transfer paper is not fed. Attached and supplied to the cleaning blade. The cleaning toner that reaches the cleaning blade by the rotation of the photoconductor is blocked here, and the surface of the photoconductor is polished by the pressing force from the cleaning blade. This removes deposits such as talc components attached to the surface of the photoreceptor.
[0016]
The important thing here is to put more cleaning toner on the photoreceptor portion corresponding to both ends in the photoreceptor axial direction of the transfer paper fed immediately before than the photoreceptor portion corresponding to the central portion. It is in. As a result, a large amount of cleaning toner is supplied to portions corresponding to both ends of the transfer paper having a large amount of deposits such as talc, and at the same time, a portion corresponding to the central portion of the transfer paper having little deposits is provided. Since only a small amount of cleaning toner is supplied to the portion, it is possible to efficiently remove deposits on the surface of the photoreceptor while reducing the amount of cleaning toner used.
[0017]
The time when the cleaning is performed with the cleaning toner placed on the surface of the photoconductor is when the paper is not fed. That is, in the continuous image forming state, there is a gap between the transfer papers and after a series of image formation is completed. Alternatively, a sheet counting means for integrating the number of formed images may be provided so that the cleaning toner is placed on the surface of the photoreceptor every time a predetermined number of images are formed. FIG. 2 shows a configuration block diagram of the image forming apparatus of the present invention. When a signal indicating that the paper is not fed is sent to the control unit 10 by the paper feed detection unit 11, the control unit 10 obtains the size of the transfer paper that has just been fed from the paper feed size detection unit 12. Then, the charging device 2 is operated to charge the surface of the photoconductor, and in the exposure device 3, the photoconductor portions corresponding to both ends of the transfer paper are larger than the photoconductor portion corresponding to the center in accordance with the size of the transfer paper. An electrostatic latent image is formed such that a large amount of cleaning toner is placed thereon. The specific shape of the electrostatic latent image will be described later.
[0018]
The formed electrostatic latent image is developed by the developing device 4 with toner. Then, the cleaning toner adhered to the photoconductor is carried to the transfer unit by rotation of the photoconductor. In the case of normal image formation, a charge having a polarity opposite to the polarity of the toner is generated by the transfer device 5, and the toner on the photoconductor is transferred to transfer paper. Without operating, the cleaning toner on the photoconductor is directly delivered to the cleaning device 7. Then, the cleaning toner in the cleaning device 7 blocks the cleaning toner on the photoconductor, and a pressing force from the cleaning blade is applied, so that the cleaning toner polishes and removes the attached matter on the photoconductor surface. .
[0019]
Here, an example of the cleaning electrostatic latent image formed on the photoconductor is shown in FIG. FIG. 3 is an expanded view of the photoconductor surface. This figure is a diagram when an electrostatic latent image 9 for cleaning toner is formed between sheets of continuous image formed on A4 length paper. In the electrostatic latent image 9, the length of the photoconductor portion 91 corresponding to both ends of the transfer paper in the photoconductor rotation direction is made longer than the length of the photoconductor portion 92 corresponding to the center of the transfer paper. The toner adhesion amount is adjusted. The photoreceptor portions 93 and 93 'are left and right margins at positions where the separation claws are actually in contact with each other, and these regions do not form an electrostatic latent image.
[0020]
FIG. 4 is a diagram illustrating a case where an electrostatic latent image 9 ′ for the cleaning toner is formed when an image is formed on A4 landscape paper. As can be understood from this figure, the width of the electrostatic latent image for cleaning in the axial direction of the photoconductor varies depending on the size of the transfer sheet that has just been fed. This is because, depending on the size of the fed transfer paper, the photoconductor portion corresponding to both end portions of the transfer paper and the portion corresponding to the central portion are respectively changed.
[0021]
As another form of the electrostatic latent image for cleaning, a latent image forming portion may be formed in a direction of an exposure scanning line as shown in FIG. Further, in the electrostatic latent images described so far, the toner adhesion amount is adjusted by changing the area in the photoconductor rotation direction while keeping the potential the same, but as shown in FIG. Alternatively, the toner adhesion amount may be adjusted by partially changing the potential of the electrostatic latent image. For example, in the case of the reversal development method, the surface potential of the photoconductor portion 91 corresponding to both ends of the transfer paper is reduced, while the surface potential of the photoconductor portion 92 corresponding to the center portion of the transfer paper is increased. As a result, the potential difference from the developing bias becomes large in the photoconductor portion 91 and a large amount of toner adheres thereto. Conversely, the potential difference becomes small in the photoconductor portion 92 and only a smaller amount of toner adheres to the photoconductor portion 91. become.
[0022]
It is preferable that the amount of toner adhered to the photoconductor corresponding to both ends of the transfer paper is 1.1 to 10 times the amount of the photoconductor corresponding to the center of the transfer paper. The specific adhesion amount is preferably in the range of 0.1 to 1 mg / cm ² . When the amount is more than 0.1 mg / cm ^2, a cleaning effect corresponding to the amount of adhered toner cannot be obtained, while when the amount is less than 0.1 mg / cm ² , a sufficient cleaning effect cannot be obtained.
[0023]
As such a cleaning toner, the developing toner stored in the developing device can be used as it is. However, in order to impart the effect of polishing the surface of the photoreceptor, the toner needs to contain an abrasive. Conventionally known abrasives can be used, and examples thereof include silica, titanium oxide, and alumina. The particle size of the abrasive is preferably in the range of 0.01 to 0.5 μm. It is preferable to add the toner to the toner in an amount of 0.01 to 1.5 wt% with respect to the toner before the addition. The method of adding to the toner may be either external addition or internal addition. Further, the toner used may be either a one-component toner or a two-component toner, and may be either magnetic or non-magnetic.
[0024]
As the cleaning blade used in the present invention, a conventionally known cleaning blade can be used, and its linear pressure and pressure contact angle may be appropriately adjusted depending on the type and peripheral speed of the photoconductor. Generally, the linear pressure of the cleaning blade is preferably in the range of 8 to 40 g / cm. If the linear pressure is less than 8 g / cm, the photoreceptor surface cannot be polished by utilizing the polishing effect of the toner. Conversely, if the linear pressure is more than 40 g / cm, the photoreceptor surface is polished more than necessary and the life of the photoreceptor Is shortened. The pressure contact angle of the cleaning blade is preferably in the range of 15 to 30 °. If the pressure contact angle is less than 15 °, a sufficient polishing effect cannot be obtained, and if the pressure contact angle exceeds 30 °, the cleaning blade may be turned up.
[0025]
From the viewpoint of improving the polishing effect of the photoconductor surface, the cleaning blade may be swung in the photoconductor axis direction. Further, from the viewpoint of extending the life of the cleaning blade and the photoconductor, the cleaning blade is provided so as to be able to contact and separate from the photoconductor, and the cleaning blade is separated from the photoconductor when the photoconductor is not rotating. You may do so.
[0026]
【Example】
Example Two components in which 0.5 wt% of silica (volume average central particle size: 0.02 μm) and 0.01 wt% of titanium oxide (volume average central particle size: 0.1 μm) are externally added to the toner weight as an abrasive. Using a non-magnetic toner (volume average center particle diameter: 10.5 μm), a printing durability test was performed using A4 paper length paper feeding by a digital copying machine “KM-4530” manufactured by Kyocera Mita. Each time an image was formed, a cleaning toner was placed on the photoconductor to clean the surface of the photoconductor. The electrostatic latent image for cleaning had the shape shown in FIG. As a result, filming did not occur on the surface of the photoreceptor until the number of printings reached 80,000.
[0027]
Comparative Example A printing durability test was performed in the same manner as in the example except that the cleaning toner was not placed on the photoconductor. As a result, filming occurred on the photosensitive member surface when the number of printings was 30,000.
[0028]
【The invention's effect】
In the image forming apparatus of the present invention, a paper feed size detecting unit for detecting a paper feed size is further provided, and the size of the immediately preceding transfer paper is detected by the paper feed size detecting unit, and the photosensitive member shaft on the transfer paper is detected. More cleaning toner adheres to the photoreceptor portions corresponding to both ends than the photoreceptor portion corresponding to the central portion in the direction to clean the photoreceptor surface, thereby reducing the amount of toner supplied to the cleaning blade. However, it is possible to effectively remove the deposits attached to the photoreceptor surface.
[0029]
When the amount of the cleaning toner adhered to the photoconductor portions corresponding to the both end portions is in a range of 1.1 to 10 times the adhesion amount of the photoconductor portion corresponding to the central portion, the toner supply amount to the cleaning blade While reducing the amount of deposits on the surface of the photoreceptor.
[0030]
Further, if the cleaning toner is not attached to the photoconductor portion where the separation claw contacts, it is possible to prevent the transfer claw from being stained with the toner by using the separation claw as a medium.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram illustrating an example of an image forming apparatus of the present invention.
FIG. 2 is an example of a control block diagram of the image forming apparatus of the present invention.
FIG. 3 is a diagram illustrating an example of an electrostatic latent image for cleaning by developing a photoconductor surface.
FIG. 4 is a diagram illustrating another example of an electrostatic latent image for cleaning.
FIG. 5 is a diagram illustrating another example of an electrostatic latent image for cleaning.
FIG. 6 is a diagram of an electrostatic latent image for cleaning used in an example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Charging device 3 Exposure device 4 Developing device 5 Transfer device 6 Separating claw 7 Cleaning device 8 Static eliminator 9, 9 ', 9 "Electrostatic latent image P for cleaning Transfer paper 10 Control unit 11 Feed detecting means 12 Paper feed size detecting means 71 Cleaning blade 91 Photoconductor portions 92 corresponding to both ends of transfer paper Photoconductor portions 93, 93 'corresponding to the center portion of transfer paper Photoconductor portions corresponding to contact areas of separation claw

Claims (3)

A charging device for charging the surface of the photoconductor, an exposure device for forming a latent image on the surface of the photoconductor charged by the charging device, and a developing device for developing the latent image on the surface of the photoconductor with toner containing an abrasive. A transfer device for transferring a toner image on the surface of the photoconductor formed by development onto transfer paper, a cleaning device having a cleaning blade for scraping off toner remaining on the surface of the photoconductor after transfer by the transfer device, Paper feed detecting means for detecting a paper feed state,
In a non-feeding state, toner for cleaning the surface of the photoconductor is attached to the surface of the photoconductor and supplied to the cleaning device, and the cleaning toner thus adhered is scraped and collected by the cleaning blade to collect the surface of the photoconductor. In the image forming apparatus for cleaning
The image forming apparatus further includes a paper feed size detecting unit that detects a paper feed size, and detects the size of the transfer paper that has been fed immediately before by the paper feed size detecting unit, and corresponds to a central portion of the transfer paper in the photoconductor axial direction. An image forming apparatus, wherein the cleaning toner adheres more to photoconductor portions corresponding to both end portions than to photoconductor portions to clean the photoconductor surface. 2. The image according to claim 1, wherein the amount of the cleaning toner adhered to the photoconductor portions corresponding to the both end portions is in a range of 1.1 to 10 times the amount of adhesion of the photoconductor portion corresponding to the central portion. Forming equipment. The image forming apparatus according to claim 1, further comprising a separation claw for separating transfer paper from a surface of the photoconductor, wherein the cleaning toner is not attached to a portion of the photoconductor that contacts the separation claw.

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