JPH04138487A - Image forming device - Google Patents

Abstract

PURPOSE:To allow always stable cleaning by constituting a cleaning blade in such a manner that the friction force of the cleaning blade in the contact part with the surface of an image carrying member exclusive of an image forming region decreases and that the cleaning blade is liable to slip with the surface of the image carrying member off the image forming region. CONSTITUTION:The friction force between the image carrying member 1 and the cleaning blade 3 off the image forming region is set smaller than the friction force between the image carrying member 1 and the cleaning blade 3 in the image forming region. Namely, the parts in contact with a photosensitive drum 1 on both end sides of the cleaning blade 3 which comes into contact with the photosensitive drum 1 off the image forming region are subjected to the treatment to lower the friction, by which these parts are constituted to the lower friction force on the surface of the photosensitive drum and to be easily slipperable therewith. Then, the generation of the vibration and peeling at the front end of the cleaning blade is prevented at the end of the cleaning blade. The always good leaning effect is maintained in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to cleaning of image forming apparatuses such as electrophotographic copying machines and printers.

[Conventional technology]

A process of developing an electrostatic latent image formed on the surface of a moving image carrier as a toner image by a developing means, and after transferring this toner image, cleaning the toner that does not contribute to the transfer and remains on the surface of the image carrier. Image forming apparatuses that repeat the process are conventionally well known.

In this type of image forming apparatus, a cleaning blade made of an elastic material such as urethane rubber is used to remove residual toner because its structure is simple, compact, and cost-effective. It has been widely used as a cleaning means.

(As is known, in many cleaning means that use a cleaning blade, the edge of the blade is brought into pressure contact with the surface of the moving image carrier from a direction opposite to that direction. However, since there is some residual toner in the image area on the surface of the image carrier, the cleaning blade is designed to remove this toner. However, conversely, the presence of this toner acts as a lubricant at the contact area between the image carrier surface and the blade edge, and the desired relative positional relationship between the two is maintained. The toner removes the toner.

However, even if the above measures are taken, under such conditions, for example, when an original with extremely low image density is continuously copied, the supply of toner that provides a lubricating effect between the blade and the image carrier is cut off. The coefficient of friction becomes extremely large,
The tip of the cleaning blade was turned around along the rotational direction of the recording medium (so-called blade turning), and the tip edge was partially damaged.

As a means to solve this problem, as shown in FIG. 6, a residual toner storage member 14 is disposed upstream of the cleaning blade in the traveling direction of the image carrier, and the remaining toner is removed from the surface of the image carrier by the cleaning blade. There has been a method of keeping the toner constantly in contact with the surface of the image carrier by collecting the residual toner between the residual toner storage member and the image carrier.

[Problem that the invention is trying to solve]

However, even with the above configuration, if originals with extremely low image density are continuously copied, the tip of the blade may curl up or the tip edge may be partially damaged. In the areas near both ends of the cleaning blade that are in contact with the image carrier outside of the area, the friction between the image carrier and the cleaning blade becomes larger, which acts as a brake on the moving image carrier. , the running of the image carrier may become unstable, the tip of the cleaning blade may vibrate,
There was a problem that the sheets would turn over, making it impossible to maintain a good leaning effect.

[Means to solve the problem]

In order to solve the above problems, the present invention provides an image carrier and
In an image forming apparatus including a cleaning blade that comes into contact with the image bearing member and removes residual toner, the frictional force between the image bearing member and the cleaning blade outside the image forming area is used to convert the friction force between the image bearing member and the cleaning blade outside the image forming area into The present invention is characterized in that the frictional force between the carrier and the cleaning blade is smaller than that between the carrier and the cleaning blade.

〔Example〕

Hereinafter, the present invention will be specifically explained with reference to the drawings.

<Embodiment 1> FIG. 1 is a schematic diagram of an embodiment showing the case where the present invention is applied to a copying machine, in which the drum is used as a cleaning means by contacting a photosensitive drum 1 as an image carrier rotating in six directions of arrows. A cleaning device 2 is provided, and a cleaning blade 3 of this cleaning device 2 is in pressure contact with the surface of the photosensitive drum 1. Further, in the vicinity of the photosensitive drum 1, a pre-exposure light source 4, a negative number charger 5, a developing device 7, a transfer charger 10, and a separation charger 11, which are components of the electrophotographic recording process, are arranged. After the surface charge of the photosensitive drum I is removed by the light source 4, the photosensitive drum 1 is uniformly charged by the -number charger 5, and a photoimage is exposed in the area 6. Form a toner image. Thereafter, the toner image formed on the surface of the photosensitive drum 1 is transferred by a transfer charger 10 to a transfer material 8'' which has passed through a passage 9, and this transfer material 8 is transferred to a toner image by a separation charger II. It is separated from the photosensitive drum 1 while being supported, and is transported by the transport means 12 to a fixing means (not shown).

On the other hand, residual toner 13 that does not contribute to the transfer and remains on the surface of the photosensitive drum 1 at the transfer site reaches the cleaning device 2 and is scraped off from the surface of the photosensitive drum 1 by the cleaning blade 3 onto a scraping sheet +5J:. Thereafter, the residual toner 13 scraped off by the cleaning blade 3 is collected by a toner storage member 14 disposed upstream of the cleaning blade 3 in the traveling direction of the photosensitive drum 1.
It is stored between the storage member l/I and the photosensitive drum 1. Among these accumulated residual toners, a portion of the toner that is in contact with the photosensitive drum 1 is conveyed again to the cleaning blade 3 as the photosensitive drum 1 runs, and the presence of this toner causes the contact between the image carrier surface and the blade edge. By acting as a lubricant in the cleaning blade 3
The image carrier is pressed and rubbed smoothly on the surface of the image carrier.

However, as described above, the toner 13 as a lubricant is always present on both ends of the cleaning blade that contacts the photosensitive drum 1 outside the width of the image area on the surface of the photosensitive drum 1 (the length in the direction perpendicular to the plane of the paper). Because of the absence of the cleaning blade 3, the frictional force between both ends of the cleaning blade 3 and the photosensitive drum 1 increases, and problems such as vibration and bending of the tip of the blade tend to occur in the regions at both ends of the cleaning blade 3. In addition, conventionally, urethane rubber has been mainly used as the material for the cleaning blade 3 due to its chemical resistance, abrasion resistance, moldability, and mechanical strength. For example, since the frictional force against the OPC photosensitive drum whose surface layer is made of a polymer resin such as polycarbonate is extremely high, in the case of such a combination, the image forming area where the toner 13 as a lubricant is not present is particularly important. Vibration and curling of the blade tip at the end of the outer cleaning blade 3 is likely to occur.

Therefore, in the present invention, in particular, the portions of the cleaning blade 3 that contact the photosensitive drum 1 on both end sides, which contact the photosensitive drum 1 outside the image forming area, are subjected to a friction reduction treatment so that the frictional force against the photosensitive drum surface is low. The structure is designed to be easy to slip, so that problems such as vibration and curling of the tip of the cleaning blade at the end of the cleaning blade are prevented from occurring.

FIG. 2 is a schematic diagram for explaining the arrangement of the photosensitive drum 1, the cleaning blade 3, the image forming area, and the cleaning blade low-friction processing area of this embodiment, and shows the image forming area on the photosensitive drum having a width of d. In order for the cleaning blade 3 to remove the residual toner 13 on the photosensitive drum 1 from the photosensitive drum 1 with respect to the width d2 (d+>a2), the width d3 of the cleaning blade 3 must be wider than the image forming width d2. (d2≦d3) Especially in the case of d2 and d3, the ends ΔdA and Δd of the cleaning blade 3
Since toner as a lubricant no longer exists in the region B, in order to reduce the frictional force between the cleaning blade 3 and the photosensitive drum 1 in this region, the end portion of the cleaning blade 3 in the region ΔdA1ΔdB is The contact portion with the photosensitive drum is treated to reduce friction.

And this cleaning blade end ΔdA, ΔdB
In this area, since there is no toner, the conditions required for the cleaning blade 3 in the image forming area, such as chemical resistance, abrasion resistance, and mechanical strength, are somewhat relaxed. It becomes possible to widen the degree of freedom in selecting materials when performing the friction treatment, and it is possible to make it possible to make the finish after the treatment, such as accuracy, less severe.

In fact, the present inventors applied the following method to an OPC photosensitive drum composed of a surface layer using polycarbonate as a polymeric resin as a binder, by cutting the end of a cleaning blade made of urethane rubber outside the image forming area as follows. When low-friction treatment was performed, there were no problems in terms of chemical resistance, abrasion resistance, mechanical strength, etc., and low friction with the photosensitive drum was achieved, reducing vibrations at the end of the cleaning blade and the tip of the cleaning blade. It was confirmed that no problems such as quitting would occur.

<Embodiment 2> FIG. 3 is a schematic diagram of the arrangement of the photosensitive drum 1, the cleaning blade 3, and the image forming area for explaining the second embodiment of the present invention. The end area Δ of the cleaning blade 3 where no toner exists
The photosensitive drum contact portions of the cleaning blade 3 of dA and ΔdB are matted.

Then, as in this embodiment, by forming minute irregularities by matting treatment on the photosensitive drum contact portion of the cleaning blade 3 in the end regions ΔdA and ΔdB, cleaning in the end regions ΔdA and ΔdB is performed. By reducing the contact area between the blade 3 and the photosensitive drum l, the frictional force applied to the cleaning blade 3 in this area can be reduced, and the vibration of the cleaning blade tip in the cleaning blade end area can be reduced. (It becomes possible to prevent this from occurring.)

Here, the end area ΔdA of the cleaning blade 3.

In order to mattify ΔdB, the average particle size must be approximately 1 to 1
The edge of the cleaning blade 3 facing the photosensitive drum is mechanically rubbed with a brush, roller, film, etc. whose surface is coated with or dispersed with highly hard powder such as glass beads, metal powder, resin powder, ceramic powder, etc. of approximately 0 μm. Bye.

In fact, the present inventors discovered that the end areas ΔdA and ΔdB of a cleaning blade made of urethane rubber outside the image forming area are
When the edge of the cleaning blade in contact with the photosensitive drum was matted by rubbing with a polyethylene terephthalate (PET) film coated with spherical silicon carbide particles with an average particle diameter of 8 μm, the edge of the cleaning blade was matted. It is possible to form fine irregularities with an average roughness of approximately 1 μm or less on the surface of the OPC photosensitive drum, which is composed of a surface layer using polycarpo as a polymer resin as a binder. It was confirmed that such problems did not occur.

Embodiment 3 FIG. 4 is a schematic diagram of the arrangement of the photosensitive drum 1 and the cleaning blade 3 in the image forming area for explaining the third embodiment of the present invention. End region Δd of cleaning blade 3 where toner does not exist
The thickness h of the cleaning blade 3 of A, ΔdB is made smaller than the thickness h2 in the image forming area ((h2,<h2).

In other words, in this embodiment, as shown in FIG. 5, the cleaning blade 3 comes into contact with the photosensitive drum I, and the frictional force generated between the cleaning blade 3 and the cleaning blade 3 when the photosensitive tram I rotates in the direction of arrow A. is cleaning blade 3
is proportional to the contact pressure when contacting the photosensitive drum 1, the end areas ΔdA and ΔdB of the cleaning blade 3
By reducing the thickness hl of the cleaning blade at , the contact pressure against the photosensitive drum 1 at the cleaning blade end areas ΔdA and ΔdB is reduced, and the frictional force with the photosensitive drum 1 is reduced. ing.

E, Young's modulus d3 Cleaning blade width 1], Cleaning blade thickness l: Cleaning play 1・Length δ・Cleaning blade deflection amount F Cleaning blade contact pressure Note that in this embodiment, the end area ΔdA of the cleaning blade 3 In order to reduce the contact pressure between the cleaning blade 3 and the photosensitive drum 1 at , ΔdB, the thickness of the cleaning blade 3 is reduced.
In order to lower the contact pressure between the cleaning blade 3 and the photosensitive drum l than the contact pressure at the image forming area, for example, a configuration is adopted in which the amount of deflection δ of the cleaning blade in the end area of the cleaning blade is reduced. The object of the present invention can also be achieved by forming the end region from urethane rubber having a small Young's modulus E.

〔Effect of the invention〕

As explained above, the electrostatic latent image formed on the surface of the moving image carrier is developed as a toner image by the developing means, and after this toner image is transferred, it remains on the surface of the image carrier without being transferred. In an image forming apparatus that repeats the process of removing toner by bringing a cleaning blade into contact with an image bearing member, the frictional force at the contact portion of the cleaning blade with the surface of the image bearing member outside the image forming area is reduced. By configuring the cleaning blade so that it easily slides against the surface of the image carrier outside the image forming area, problems such as vibration and curling of the tip of the cleaning blade at the end of the cleaning blade can be prevented. This makes it possible to provide an image forming apparatus that can maintain stable leaning action at all times.

[Brief explanation of drawings]

1 is a diagram showing a first embodiment of an image forming apparatus to which the present invention is applied; FIG. 2 is a diagram for explaining the first embodiment of FIG. 1;
The figure shows a second embodiment of the invention, FIG. 4 shows a third embodiment of the invention, and FIG. 5 is a diagram for explaining the third embodiment of FIG. Model Diagram FIG. 6 is a schematic diagram showing a conventional image forming apparatus. I...Photosensitive drum 2...Cleaning device 3...Cleaning plate 4...Pre-exposure light source 5...-number charger 6...Photoimage exposure section 7/Developer 8...Transfer material 9...passage] 0...transfer charger 11...separation charger]2...conveying means 13...residual toner 14...residual toner storage member 15...squeezing sheet 16...・Discharge toner transport screw = 5"

Claims (7)

[Claims] (1) In an image forming apparatus including an image bearing member and a cleaning blade that comes into contact with the image bearing member and removes residual toner, the frictional force between the image bearing member and the cleaning blade outside the image forming area An image forming apparatus characterized in that the frictional force between the image carrier and the cleaning blade is smaller than the frictional force between the image carrier and the cleaning blade in the image forming area. (2) The image forming apparatus according to claim 1, wherein a contact portion of the cleaning blade that contacts the image carrier outside the image forming area is subjected to a friction reduction treatment. (3) The second aspect of the present invention is characterized in that the friction reduction treatment is the internal addition of fluorinated graphite, fluororesin, or porous nylon powder to the cleaning blade.
The image forming apparatus described in . (4) The image forming apparatus according to claim 2, wherein the friction reduction treatment is coating the cleaning blade with a fluorine-based paint or a Si-based paint. (5) The image forming apparatus according to claim 2, wherein the friction reduction treatment is a surface treatment of the cleaning blade using a fluorine-based treatment agent or a Si-based treatment agent. (6) Claim 2, wherein the friction reduction treatment is a matte treatment of the cleaning blade.
The image forming apparatus described in . (7) The first aspect of the present invention is characterized in that the contact pressure of the contact portion of the cleaning blade that contacts the image carrier outside the image forming area is smaller than the contact pressure in the image forming area. The image forming apparatus described in .