JP2008233338A - Cleaning blade - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning blade with excellent durability, which is prevented from being chipped and abnormally worn by suppressing the occurrence of stick-slip phenomenon, and to provide a cleaning device and an image forming apparatus. <P>SOLUTION: The cleaning blade 1 having a hardness of 65-80, which is arranged in a counter direction y with respect to the rotational direction x of an image carrier 2 whose surface has a coefficient of static friction of 0.3-0.5, while bringing the edge portion of the cleaning blade 1 into contact with the image carrier, has a groove 3 along a longitudinal direction in the side surface 1a on the upstream side in the rotational direction of the image carrier, of the side surfaces constituting a contact edge portion with the image carrier, of the cleaning blade. The cleaning device is provided with the cleaning blade and the image forming apparatus is provided with the cleaning device. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a cleaning blade, a cleaning device, and an image forming apparatus.

  In an image forming apparatus such as an electrophotographic image forming apparatus, a toner image is formed on an image carrier such as a photosensitive member or an intermediate transfer member, and this toner image is transferred to a transfer material to obtain an output image. It is necessary to clean the image carrier so that the toner remaining on the image carrier after performing the above does not affect the next image formation. A cleaning blade is widely used as a cleaning means. Conventionally, the cleaning blade has a simple rectangular parallelepiped shape.

  However, as shown in FIG. 7, when the cleaning blade 101 is arranged in the counter direction y with respect to the rotation direction x of the image carrier while the edge portion is in contact with the image carrier 102, the image carrier 102. With the rotation / driving of the image, the edge portion vibration b occurs between the rotation direction of the image carrier and the direction opposite to the rotation direction, and instantaneously higher pressure than normal is generated (stick-slip phenomenon). ). As a result, there was a problem in the durability of the blade due to chipping or abnormal wear at the edge portion in contact with the image carrier during long-term use.

Therefore, attempts have been made to round the edge portion (Patent Document 1). However, a relatively large contact force is required to ensure cleaning properties.
Further, although it is conceivable to provide a protrusion on the edge portion, the stick-slip phenomenon still occurs, so that the blade could not obtain sufficient durability.
JP-A-6-332350

  SUMMARY OF THE INVENTION An object of the present invention is to provide a cleaning blade, a cleaning device, and an image forming apparatus with excellent durability that suppress the occurrence of a stick-slip phenomenon and prevent chipping and abnormal wear of the cleaning blade.

  The present invention has a hardness of 65 to 80 arranged in the counter direction with respect to the rotation direction of the image carrier while bringing the edge portion into contact with the image carrier having a static friction coefficient of 0.3 to 0.5 on the surface. The cleaning blade has a groove along the longitudinal direction on the upstream side surface in the rotational direction of the image carrier among the side surfaces constituting the contact edge portion with the image carrier in the cleaning blade. The present invention relates to a cleaning blade, a cleaning device including the cleaning blade, and an image forming apparatus including the cleaning device.

  According to the present invention, when the image carrier is rotated and driven, local stress concentration occurring in the cleaning blade can be alleviated, so that the occurrence of the stick-slip phenomenon can be suppressed. Therefore, chipping and abnormal wear of the cleaning blade can be prevented, and the life of the cleaning blade can be kept long, so that stable and good cleaning properties can be maintained over a long period of time.

  A cleaning blade according to an embodiment of the present invention is used by being arranged in a counter direction with respect to a rotation direction of an image carrier while contacting an edge portion with the image carrier. In other words, the cleaning blade is inclined and brought into contact with and arranged to face the rotation of the image carrier.

  For example, as shown in FIG. 1, the cleaning blade 1 is disposed in a counter direction y with respect to the rotation direction x of the image carrier, with the edge portion in contact with the image carrier 2. FIG. 1 is a schematic sectional view when the cleaning blade is used in contact with the image carrier, and is a sectional view perpendicular to the axial direction of the image carrier 2.

  The cleaning blade 1 is arranged so that its longitudinal direction is parallel to the axial direction of the image carrier 2, and the image of the side surfaces (1 a, 1 b) constituting the contact edge portion of the cleaning blade 1 with the image carrier 2. Grooves 3 are continuously provided along the longitudinal direction on the side surface 1a on the upstream side in the rotation direction x of the carrier. By forming the groove on the side surface 1a of the cleaning blade 1, it is possible to alleviate local stress concentration that occurs in the cleaning blade during rotation and driving of the image carrier, and as a result, the occurrence of the stick-slip phenomenon can be suppressed. In a cleaning blade that does not have a groove, local stress concentration occurs when the image carrier is rotated and driven, so that a stick-slip phenomenon occurs, and the cleaning blade is chipped or abnormally worn.

  The dimension and formation position of the groove are not particularly limited as long as the object of the present invention is achieved. For example, a groove having a depth of 5 to 100 μm, particularly 10 to 100 μm, and a width of 5 to 100 μm, particularly 10 to 100 μm, can be formed at a position 10 to 100 μm away from an edge in contact with the image carrier in the cleaning blade.

  In the present specification, as shown in FIG. 2 which represents the schematic cross section perpendicular to the longitudinal direction of the cleaning blade, the depth is the maximum carving depth and width from the groove forming surface 1a. Is the maximum width, and the formation position is the distance from the contact edge with the image carrier. The thickness of the cleaning blade is usually about 1 to 3 mm.

The cross-sectional shape of the groove has a quadrangular shape in FIG. 2, for example, but is not limited to this, and may be other polygonal shapes (triangular shape, pentagonal shape, etc.), semicircular shape, etc. May be.
Although only one groove is formed in FIG. 2, the groove is not limited to this, and two or more grooves may be formed along the longitudinal direction.

  The region other than the groove 3 region on the side surface 1a on the upstream side of the cleaning blade 1 does not have to have a planar shape. For example, a convex portion may be continuously provided in the longitudinal direction. From the viewpoint of moldability, the region other than the groove 3 region on the side surface 1a preferably has a planar shape.

The cleaning blade 1 has a hardness of 65 to 80, and is usually made of a known cleaning blade material such as polyurethane rubber. If the hardness is too low, the edge portion is likely to be drawn into the rotation of the image carrier, and a stick-slip phenomenon is likely to occur.
The hardness is a value measured by a rubber hardness meter (ESA type; manufactured by Elastron).

  The cleaning blade 1 can be manufactured by forming a molded body such as a rectangular parallelepiped having a predetermined dimension by extrusion molding, and forming a groove having a predetermined dimension at a predetermined position using an end mill cutter.

  The contact condition of the cleaning blade when placing the cleaning blade 1 in contact with the image carrier is not particularly limited. For example, the contact angle may be 10 to 20 ° and the contact force may be 10 to 40 N / m. .

The contact angle is a so-called effective contact angle, and is a schematic sketch when the cleaning blade 1 is arranged. As shown in FIG. 9, the contact state of the cleaning blade 1 and the image carrier when the image carrier 2 is stopped. The angle A is the tip of the contact portion with the body 2.
As shown in FIG. 9, the contact force is a force B in a state where the cleaning blade 1 is in pressure contact with the image carrier 2 and can be controlled by the contact angle A and the biting amount C.

The image carrier to which the cleaning blade 1 is brought into contact has a surface static friction coefficient of 0.3 to 0.5, and may be, for example, a so-called photoconductor, or toner formed on the surface of the photoconductor. An intermediate transfer member for transferring the toner image onto a recording material such as paper after the image is transferred to the surface of the image recording medium may be used. If the static friction coefficient is too large, the edge portion is easily drawn into the rotation of the image carrier, and a stick-slip phenomenon is likely to occur.
The static friction coefficient is a value measured by Tribogear Muse 94iII (manufactured by Shinto Kagaku).

  The peripheral speed and outer diameter of the image carrier are not particularly limited, and for example, the peripheral speed may be 30 to 500 mm / s, and the outer diameter may be 20 to 100 mm.

  When the cleaning blade 1 is used in a cleaning device, as shown in FIG. 1, the cleaning blade is in a state in which the upstream side surface 1 a of the edge portion is drawn into the rotation of the image carrier 2 by the rotation and driving of the image carrier 2. However, since the state is continuously maintained, vibration (stick-slip phenomenon) is prevented.

  An example of the cleaning device is shown in FIG. In FIG. 3, a cleaning device 10 has a cleaning blade 1 and a cleaning tank 11 for storing toner separated and removed from the surface of the image carrier by the cleaning blade, and is separated and removed as desired. And a waste toner conveying device 12 for guiding the discharged toner into the cleaning tank 11.

  The cleaning device can be installed in an image forming apparatus that forms a toner image on an image carrier and transfers the toner image to a transfer material to obtain an output image. An example of the image forming apparatus is shown in FIG. FIG. 4 is a schematic cross-sectional view of a tandem type full-color image forming apparatus. In FIG. 4, the full-color image forming apparatus 30 has four image forming units 20, and the toner image developed in each image forming unit 20 is primarily transferred to the intermediate transfer belt 21 and then conveyed from the paper supply device 23. The image is transferred to the transfer medium by the secondary transfer roller 22. The transfer medium to which the toner image is transferred is further conveyed, fixed by the fixing device 24, and discharged.

  Each image forming unit 20 is equipped with an image carrier (photoconductor) 2, a charging device 15, an exposure device 16, a developing device 17, and a cleaning device 10, and the cleaning blade 1 described above is used in the cleaning device 10. Is done. In FIG. 4, the cleaning blade 1 is held by a holder 18 made of sheet metal.

Experimental example 1
(Manufacture of cleaning blades)
A rectangular parallelepiped (300 mm × 20 mm × 2 mm) having a predetermined hardness made of polyurethane rubber was obtained by extrusion molding. Next, a groove having a predetermined dimension was formed at a predetermined position by an end mill cutter, and a cleaning blade as shown in FIG. 2 was obtained.

(An endurance test)
The cleaning blade is incorporated into a printer (bizhub C250; manufactured by Konica Minolta Co., Ltd.) as a cleaning blade for the photosensitive member, and a durability test of 100,000 sheets is performed under predetermined conditions, and the stick-slip phenomenon, the edge of the cleaning blade, and the image holding immediately after cleaning The residual toner on the body was observed. As shown in FIG. 1, the cleaning blade was placed in the counter direction y with respect to the rotation direction x of the image carrier, with the edge portion in contact with the image carrier. The hardness of the cleaning blade, the depth, width and formation position of the groove, and the static friction coefficient of the image carrier are as described in the table, and other conditions are as follows.
Cleaning blade; contact angle 13 °, contact force 30 N / m;
Image carrier: peripheral speed 165 mm / s, outer diameter 30 mm.

○: No stick-slip phenomenon occurred, no chipping or abnormal wear was observed on the edge of the cleaning blade, and no residual toner on the image carrier was observed;
Δ: Stick-slip phenomenon sometimes occurred, but no chipping and abnormal wear were observed at the edge of the cleaning blade, and no residual toner on the image carrier was observed;
X: Stick-slip phenomenon occurred, chipping and abnormal wear were observed on the cleaning blade edge, and residual toner was observed on the image carrier;
-; The test was not conducted.

Experimental example 2
The transition of the contact force accompanying the change in the rotation amount of the image carrier was measured under the conditions of the groove depth of 50 μm and the width of 50 μm in Table 10 of Experimental Example 1 (hereinafter referred to as Condition A), and the results are shown in FIG. .
On the other hand, the transition of the abutting force accompanying the change in the rotation amount of the image carrier is measured under the same condition as the condition A (hereinafter referred to as condition B) except that no groove is formed. Indicated.
Further, for conditions A and B, the transition of the edge moving distance accompanying the change in the rotation amount of the image carrier was measured and is shown in FIG. The edge movement distance is based on the contact point between the image carrier and the cleaning blade when the image carrier is stationary, and how far the contact point has moved from the origin when the image carrier is driven (as shown in FIG. 1). This is the distance traveled.

5A to 5C have a common horizontal axis.
When the groove is formed, as shown in FIG. 5A, a stable contact force is maintained.
When the groove is not formed, in a region where the waveform is disturbed in FIG. 5B, a stick-slip phenomenon in which the blade cannot withstand the generated stress and the contact portion vibrates occurs. At this time, about twice the contact force as usual is applied to the blade.
FIG. 5C shows that when no groove is formed, the edge portion temporarily returns to the upstream side when the rotation amount of the image carrier is about 0.06 mm. On the other hand, when the groove is formed, it can be seen that a stable driving state is maintained.

Experimental example 3
The simulation of the stress which generate | occur | produces about the cleaning blade which has a groove | channel, and the cleaning blade which does not have a groove | channel was performed, and the result was shown in FIG. 6 and FIG. 6 and 8 both show the contact edge portion of the cleaning blade with the image carrier in the initial stage when the image carrier is driven, and shows that the smaller the hatched interval, the greater the generated stress. The cleaning blade having a groove is a blade of the above condition A, and the cleaning blade having no groove is a blade of the above condition B.

  6 and 8, it is clear that the concentration of the generated stress is reduced and the stress is dispersed in the cleaning blade in which the groove is formed, as compared with the cleaning blade in which the groove is not formed.

  The cleaning blade of the present invention is useful for cleaning an image carrier such as a photosensitive member or an intermediate transfer member.

It is a schematic sectional drawing which shows the relationship between the cleaning blade of one Embodiment of this invention, and an image carrier. It is an expanded sectional view of the above-mentioned cleaning blade. It is a schematic sectional drawing of an example of the cleaning apparatus provided with the said cleaning blade. It is a schematic sectional drawing of an example of the image forming apparatus provided with the said cleaning blade. (A) is a graph showing a transition of the abutting force of the cleaning blade with a change in the rotation amount of the image carrier, and (B) is a graph of a transition of the abutting force of the conventional cleaning blade with a change in the rotation amount of the image carrier. (C) is a graph showing the transition of the edge moving distance accompanying the change in the rotation amount of the image carrier for the cleaning blade and the conventional cleaning blade. FIG. 6 is a schematic diagram showing a simulation result of stress generated in the cleaning blade in the initial stage of driving the image carrier. It is a schematic sectional drawing which shows the relationship between the conventional cleaning blade and an image carrier. It is a schematic diagram showing the simulation result of the stress generated in the conventional cleaning blade in the early stage of driving the image carrier. It is a schematic sketch for demonstrating the contact angle and contact force at the time of arrange | positioning a cleaning blade.

Explanation of symbols

  1: cleaning blade, 2: image carrier, 3: groove, 10: cleaning device, 11: cleaning tank, 12: waste toner conveying device.

Claims (4)

  A cleaning blade having a hardness of 65 to 80 arranged in a counter direction with respect to the rotation direction of the image carrier while bringing the edge portion into contact with the image carrier having a static friction coefficient of 0.3 to 0.5 on the surface. A cleaning blade having a groove along the longitudinal direction on a side surface upstream of the rotation direction of the image carrier among the side surfaces constituting the contact edge portion with the image carrier in the cleaning blade .   2. The cleaning blade according to claim 1, wherein the cleaning blade has a groove having a depth of 5 to 100 [mu] m and a width of 5 to 100 [mu] m at a position 10 to 100 [mu] m away from an edge in contact with the image carrier.   A cleaning device comprising the cleaning blade according to claim 1.   An image forming apparatus comprising the cleaning device according to claim 3.

Images