JP2003215999A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system wherein filming on a photoreceptor is prevented without making the device large in size and without increasing the cost, and while maintaining the satisfactory mechanical durability of the photoreceptor. <P>SOLUTION: As for the image forming apparatus provided with a cleaning device equipped with a cleaning blade coming into contact with the surface of the latent image carrier in order to remove and recover the toner remaining on the latent image carrier after a toner image is transferred, and a control part, the cleaning device is provided with a toner removing roller 28C2 coming into contact with the surface of the latent image carrier on the upstream side of the contact position of the cleaning blade 28C1 in the rotating direction of the latent image carrier 25C, and the toner removing roller is rotated in the same direction as the rotating direction of the latent image carrier by the control part at the time of forming the image, but, at the optional time other than the image forming operation, the toner removing roller is rotated in a direction opposite to the rotating direction of the latent image carrier. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile machine or the like, and particularly, a conventional problem when a brush roller is used as a means for cleaning a latent image carrier. The present invention relates to an image forming apparatus.

[0002]

2. Description of the Related Art Copiers, facsimile machines, printers,
One of the image forming processes executed in an image forming apparatus using an electrophotographic system such as a printing machine is a photosensitive member cleaning process. The photoconductor cleaning process removes the toner remaining on the surface of the photoconductor after transferring the toner image formed on the surface of the photoconductor, which is a latent image carrier, onto a transfer medium such as paper, so as to prevent the subsequent image formation. This is a process for eliminating an adverse effect. As a method of this photoreceptor cleaning process, a method is known in which a cleaning blade formed of an elastic body such as urethane rubber is brought into contact with the surface of the photoreceptor to scrape off residual toner. Further, a method in which a rotating toner removing roller is brought into contact with the surface of the photoconductor is also known, and a cleaning process can be performed in combination with the cleaning blade or alone.

Here, as a photoconductor used in an electrophotographic method widely used in copying machines, printers and the like, an organic photosensitive material is generally used because of its advantages such as low cost, mass productivity and no pollution. Is coming. However, the organic photoreceptor has lower wear resistance and is inferior in durability as compared with the inorganic photoreceptor. Furthermore, in recent years, there has been a demand for downsizing of electrophotographic systems, the photoconductor has been forced to have a smaller diameter, and mechanical durability centering on wear resistance is strongly demanded. This is a disadvantageous situation for organic photoreceptors having low durability. Further, as another problem peculiar to the system using the photoconductor, in addition to the above-mentioned problem of abrasion resistance, melted toner adheres to the photoconductor surface or other components adhere to the photoconductor surface. There is a problem of so-called photoreceptor filming. From the viewpoint of photoreceptor wear, the problem of photoreceptor filming is
It can be considered that this occurs because the abrasion speed of the surface of the photoconductor is too slow, and by maintaining the balance between both abrasion and filming, the system of the image forming apparatus using the photoconductor can be appropriately established. For example, Patent No. 309
In the invention described in Japanese Patent No. 3422, two toner removing roller brush rollers are brought into contact with the surface of the photoconductor, and one brush roller is rotated so that the moving direction is the same direction as the photoconductor at the contact portion. The other brush roller is configured such that the contact portion moves in the opposite direction.

[0004]

However, the patent No. 309
In the invention described in Japanese Patent No. 3422, it is necessary to provide two brush rollers around the photoconductor, and it is inevitable that the size of the entire apparatus is increased. In particular, among full-color image forming apparatuses using electrophotography, a system for forming a single color image is used.
In so-called tandem type devices that are installed in parallel, if the size of each system increases, the size of the entire device increases,
In order to increase the cost of the device body, it is necessary to miniaturize each system as much as possible. In order to reduce the size of the entire apparatus and each system, it is necessary to maintain sufficient durability of the photoconductor with a single brush roller while maintaining sufficient cleaning performance that does not cause filming.
By rotating the brush roller so that the moving direction is the same in the contact portion with the photoconductor, the mechanical durability can be maintained without giving an excessive frictional force to the photoconductor surface. The performance of cleaning toner and foreign matters from the surface is inferior. Further, when the brush roller is rotated so that the moving direction is opposite to the contact portion with the photoconductor, the cleaning performance is excellent, but the durability on the latent image carrier side cannot be maintained. In order to satisfy the above-mentioned two contradictory requirements, for example, in a predetermined rotation direction, the conditions such as the material of the brush roller, the fiber diameter, and the flock density are limited to predetermined values, so that a balance between cleaning performance and durability is secured to some extent However, since these setting conditions include fluctuation factors that depend on the temperature and humidity environment of the atmosphere, paper type, etc., even if the various conditions are limited to a fixed value, fluctuations in the surrounding environment etc. It is unavoidable that the cleaning performance is deteriorated due to the adverse effect. The object of the present invention has been made in view of the problems in the conventional latent image carrier and the image forming apparatus using the same, and has sufficient mechanical durability of the photoconductor without increasing the size and cost of the apparatus. It is an object to provide a system in which photoconductor filming does not occur while maintaining the above.

[0005]

In order to solve the above problems, the invention of claim 1 provides a latent image carrier for carrying an electrostatic latent image, and a toner image is formed by supplying toner to the electrostatic latent image. A developing device for forming, a transfer device for transferring the toner image on the latent image carrier onto a transfer material, and a latent image for removing and collecting toner remaining on the latent image carrier after transferring the toner image. In an image forming apparatus including a cleaning device including a cleaning blade that contacts the surface of the carrier, and a controller, the cleaning device is located upstream of the contact position of the cleaning blade in the rotational direction of the latent image carrier. And a toner removing roller that comes into contact with the surface of the latent image carrier, and the control unit rotates the toner removing roller in the same direction as the latent image carrier during the image forming operation to remove the toner at any time other than the image forming operation. Laura Wherein the rotating the image bearing member and the opposite direction. According to the present invention, since the toner removing roller is rotated in the same direction as the latent image carrier during the image forming operation, the surface of the latent image carrier is adhered without being rubbed, damaged or worn by the excessive rubbing force. While the toner and foreign matter can be removed, the latent image carrier is idled in the normal rotation direction (or stopped at any time other than the image forming operation, for example, when a predetermined number of images have been formed). Since the toner removal roller is rotated in the direction opposite to the normal rotation direction of the latent image carrier, it is possible to accurately remove the adhered toner or the like that is causing filming. As a result, it is possible to prevent deterioration of the durability of the latent image carrier while improving the cleaning property.

According to a second aspect of the present invention, in the first aspect, the toner removing roller is composed of an elastic member having conductivity. By forming the toner removing roller with a conductive material, the toner removing efficiency can be improved. The invention of claim 3 is the same as claim 1 or 2.
In the above, the toner removing roller is a conductive brush roller. By configuring the toner removing roller by a conductive brush roller, it is possible to enhance the effect of removing the adhered toner and adhering it to the brush side. A fourth aspect of the present invention is characterized in that, in the first, second or third aspect, a predetermined DC bias is applied to the conductive brush roller. By applying a DC bias, it is possible to easily remove the toner that is electrically charged and firmly attached. According to a fifth aspect of the present invention, in the first, second, third, or fourth aspect, the conductive brush roller is grounded. By using a grounded conductive brush roller, the charged toner can be neutralized to facilitate removal.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to the embodiments shown in the drawings. FIG. 1 is a diagram showing one of image forming apparatuses according to an embodiment of the present invention. The image forming apparatus shown in the figure is a copying machine or a printer capable of forming a full-color image. The image forming apparatus to which the present invention is applied includes, of course, not only the color image forming apparatus illustrated and described, but also a copying machine, a printer, a facsimile apparatus, and the like which target an image of a single color. The full-color image forming apparatus 20 shown in FIG. 1 includes image forming apparatuses 21C, 21Y, and 21M that form an image for each color according to an original image.
21BK and each image forming device 21C, 21Y, 21M, 21
A transfer device (transfer belt and transfer roller) 22 arranged to face the BK, and image forming devices 21C, 21Y, 21
The manual feed tray 23 and the paper feed cassette 24 as sheet medium supply means for supplying various sheet media (transfer material) to the transfer area where the M and 21BK and the transfer device 22 face each other.
And the sheet-shaped mediums respectively conveyed from the manual feed tray 23 and the paper feed cassette 24, the image forming devices 21C, 21Y,
The image forming apparatus includes a registration roller 30 that is supplied at the timing of image formation by 21M and 21BK, and a fixing device 1 that fixes the sheet medium after transfer in the transfer area. The image forming apparatus 20 includes plain paper generally used for copying, OHP sheets, 90K paper such as cards and postcards, thick paper having a basis weight of approximately 100 g / m ² or more,
Any so-called special sheet having a large heat capacity such as an envelope can be used as the sheet medium. The image forming devices 21C, 21Y, 21M, and 21BK develop the respective colors of cyan, yellow, magenta, and black, and the colors of the toners used are different, but the configurations of the image forming devices are the same. Here, for the sake of convenience, the configuration of the cyan image forming device 21C is changed to each of the image forming devices 21C, 21Y, and 21.
A typical example of M and 21BK will be described. The cyan image forming device 21C includes a charging device 27C, a developing device 26C, and a cleaning device 28C, which are sequentially arranged along the rotation direction A of the photosensitive drum 25C, and exposes between the charging device 27C and the developing device 26C. A known configuration for receiving the light 29C is used. The image forming apparatus 20 shown in FIG.
2 is arranged diagonally, so the transfer device 2 in the horizontal direction
The occupied space of 2 can be reduced. Each of the image forming devices 21C, 21Y, 21M, and 21BK is installed in the image forming apparatus 20 in a unit configuration as shown in the enlarged cross-sectional views of FIGS. The image forming device unit 21C shown in FIG. 2 includes a photoconductor drum 25C (for convenience, the image forming device 21C will be described below.
A charging device 27C and a cleaning device 28C are arranged.

In FIG. 2, the cleaning device 28C
Is a cleaning blade 28C1 that contacts the photoconductor drum 25C at the leading edge to scrape off the residual toner, and a brush roller (toner removing roller) that captures the toner from the photoconductor 25C and collects the toner scraped off by the cleaning blade 28C1. ) 28C2, and a waste toner conveying means 28C3 including a screw auger for conveying the toner collected by the brush roller 28C2 toward a waste toner containing portion (not shown). The toner removing roller may be a roller other than the brush roller. The brush roller (toner removing roller) 28C2 is rotatably driven by a motor (not shown) controlled by a controller (not shown), and at the time of normal image formation, as shown by the middle arrow B direction in FIG.
It is rotationally driven in the same direction as the photoconductor 25C at the contact portion with 5C. As described above, the normal residual toner removing operation is performed during normal image formation. Then, in a predetermined cycle, for example, the number of image formations in the image forming apparatus 20 is
At the end of the first print command that exceeds 0 sheets, the operation mode of the image forming apparatus 20 shifts from the normal mode to the filming removal mode, and the brush roller is driven by a drive source different from the photosensitive drum 25C. 28C2 is rotationally driven in the direction opposite to the rotation direction of the photoconductor drum 25C at the contact portion with the photoconductor drum 25C as indicated by the arrow C direction in FIG. , Remove other foreign matter. In other words, the filming removal mode is used in the photoconductor drum 25 at the time other than the image forming operation.
While rotating C, move the brush roller 28C2 in the reverse direction C
It is a mode to rotate to. The brush (flocking) that constitutes the brush roller 28C2 is formed of conductive fibers, and a predetermined bias is applied from a bias applying means (not shown) or is grounded. The voltage value and the like when applying the bias can be appropriately set according to the system used, the toner, and the like. By applying a DC bias to the brush roller made of a conductive fiber, it becomes possible to easily remove the charged toner and foreign matter. Also, grounding the brush roller makes it possible to easily remove similarly charged toner and foreign matter.

[0009]

According to the present invention, photoreceptor filming occurs while the photoreceptor has sufficient mechanical durability without increasing the size and cost of the apparatus due to an increase in the number of cleaning parts. It is possible to provide a system without a problem. According to the invention of claim 1, since the toner removing roller is rotated in the same direction as the latent image carrier during the image forming operation, the surface of the latent image carrier is not scratched, damaged or worn by an excessive sliding force. While adhering toner and foreign matter can be removed, the latent image carrier is rotated in the normal rotation direction at any time other than the image forming operation, for example, when the predetermined number of images have been formed. Alternatively, since the toner removing roller is rotated in the direction opposite to the normal rotation direction of the latent image carrier while stopping it), it is possible to accurately remove the adhered toner and the like that is causing filming. As a result, it is possible to prevent deterioration of the durability of the latent image carrier while improving the cleaning property. According to the invention of claim 2, the toner removing roller is made of a conductive material, so that the toner removing efficiency can be improved. According to the third aspect of the present invention, by configuring the toner removing roller by the brush roller having conductivity, it is possible to enhance the effect of removing the attached toner and attaching it to the brush side. According to the invention of claim 4, by applying a DC bias to the brush roller, it is possible to easily remove the toner that has been charged and firmly attached. According to the fifth aspect of the present invention, by using the electrically conductive brush roller which is grounded, the charged toner can be neutralized to facilitate the removal.

[Brief description of drawings]

FIG. 1 is a schematic diagram for explaining an example of an image forming apparatus to which a cleaning device and a latent image carrier according to an embodiment of the present invention are applied.

FIG. 2 is a schematic diagram showing an image forming device unit in the image forming apparatus shown in FIG.

FIG. 3 is an operation explanatory view showing a situation in which the rotation direction of the brush roller is changed in the image forming apparatus unit shown in FIG.

[Explanation of symbols]

20: image forming apparatus, 21C, 21M, 21Y, 21B
K: image forming device, 25C, 25M, 25Y, 25BK: photoconductor drums 27C, 27M, 27 which are latent image carriers
Y, 27BK: Charging device, 28C, 28M, 28Y, 2
8K: Cleaning device, 28C1, 28M1, 28Y
1, 28K1: Cleaning blade, 28C2, 28
M2, 28Y2, 28K2: Brush roller

Claims (5)

[Claims] 1. A latent image carrier that carries an electrostatic latent image, a developing device that supplies toner to the electrostatic latent image to form a toner image, and a transfer material that transfers the toner image on the latent image carrier. A transfer device that transfers the toner image onto the upper surface, a cleaning device that includes a cleaning blade that contacts the surface of the latent image carrier to remove and collect the toner remaining on the latent image carrier after transferring the toner image, and a controller. In the image forming apparatus, the cleaning device includes a toner removing roller that comes into contact with the surface of the latent image carrier on the upstream side in the rotation direction of the latent image carrier with respect to the contact position of the cleaning blade, Is characterized in that the toner removal roller is rotated in the same direction as the latent image carrier during the image forming operation, and the toner removal roller is rotated in the opposite direction to the latent image carrier at any time other than the image forming operation. Forming equipment . 2. The toner removing roller is composed of an elastic member having conductivity.
The image forming apparatus according to item 1. 3. The image forming apparatus according to claim 1, wherein the toner removing roller is a conductive brush roller. 4. A predetermined DC bias is applied to the conductive brush roller.
Or the image forming apparatus according to item 3. 5. The image forming apparatus according to claim 1, 2, 3, or 4, wherein the conductive brush roller is grounded.