JP2001228767A - Cleaning blade - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning blade which comes into contact with a photoreceptor drum surface of an image forming device in a counter system and surely removes fine particle toner in an image forming region. SOLUTION: Since both ends parts of an edge 18 are extended as projecting parts 42 in a counter direction in an non image forming region N of a cleaning blade 40 coming into sliding contact with a photoreceptor drum 16, 'turning-up' or chipping is not generated at an edge terminal 46 even when press-contacting force of the cleaning blade 40 is increased and residual toner on the photoreceptor drum 16 can be surely removed even when the residual toner is an extra fine particle.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a counter type cleaning blade capable of satisfactorily removing residual toner on an image carrier in an electrophotographic process.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as an electrophotographic copying machine, toner remaining on a photosensitive drum as an image carrier is removed so as not to hinder the next image formation. Generally, a rubber cleaning blade is brought into contact with the photosensitive drum to scrape off untransferred toner so as not to damage the organic photoconductor (OPC) applied to the surface of the photosensitive drum.

[0003] Recently, as the fineness of toner for the purpose of improving image quality has been advanced, a more reliable scraping function has been required for the contact between the cleaning blade and the photosensitive drum. Therefore, in principle, a counter method is applied in which stress can be concentrated on the contact portion of the cleaning blade edge by line contact, and fine toner can be reliably removed.

In the counter system, the contact angle of the axis along the lower surface of the cleaning blade with respect to the tangent of the outer circumferential circle of the photosensitive drum is maintained at an appropriate acute angle exceeding the friction angle, and a line is formed between the cleaning blade edge and the photosensitive drum surface. When the contact pressure force is properly maintained, the toner particles push up the edge to a height corresponding to the particle size by the bonding force with the photosensitive drum surface and pass between the photosensitive drum and the cleaning blade edge. Absent.

[0005]

However, there is a force relationship as shown in FIG. 6 between the cleaning blade and the photosensitive drum which come into contact with each other in a counter system. That is, a pressing force F1 against the photosensitive drum 103 and a frictional resistance F2 generated by the rotation of the photosensitive drum 103 are generated at the tip 102 of the cleaning blade 101. Here, when the component force F1 ′ of F1 <F2, “turning” 104 occurs on the cleaning blade 101.

Once the "turn-up" 104 occurs, the "turn-up" 104 lifts the cleaning blade 101, and the cleaning blade 101 is entirely lifted by the interposition of the "turn-up" 104.
Contact with the three surfaces cannot be maintained at all, and an image defect due to residual toner occurs.

[0007] When the longitudinal edge of the cleaning blade is brought into contact with the photosensitive drum with an ordinary strip-shaped cleaning blade, if the magnitude of the contact angle and the pressing force applied to the cleaning blade are inappropriate, the cleaning blade edge may be damaged. In addition to the above-described "turn-up", blade edge loss caused by abnormal vibration noise due to stick slip or the like makes toner removal impossible. As a result, the untransferred toner remains as streak-like stains, which hinders the next image formation.

On the other hand, fine particles of toner function as a lubricant on the cleaning blade that contacts the image forming area of the photosensitive drum, but there is no toner in the non-image forming area of the photosensitive drum. Not lubricated. Moreover, the conditions are different between the inside and the both ends of the cleaning blade, whereas the inside has a continuous support on both sides, but the end has no continuous support on only one side, and the deformation resistance against external force is inside. It is much lower than that.

Therefore, when the cleaning blade in the image forming area is brought into contact with the cleaning blade under appropriate conditions, the friction in the cleaning blade in the non-image forming area becomes excessive and the brake is applied. In this state, abnormal vibration noise due to “turning” or stick-slip, and loss of the blade edge are extremely likely to occur. Since the cleaning blade is made of rubber, the abnormalities occurring at both ends easily propagate to the inside of the image forming area and constitute a predisposition to the image forming failure.

Therefore, as a countermeasure against "turning over" of the cleaning blade, for example, means for adhering members for reducing frictional force to both ends of the cleaning blade (actually known as 7-
No. 9171), means for chamfering edges at both ends of a cleaning blade to reduce frictional force (JP-A-11-9511)
No. 631) and means for reinforcing the holder of the cleaning blade (JP-A-8-292689). However, these means require complicated secondary processing in addition to the formation of the cleaning blade, so that an increase in cost cannot be avoided.

Accordingly, an object of the present invention is to provide a counter-type cleaning blade which does not require a complicated process, prevents "turn-up" which is likely to occur in a non-image forming area, and reliably removes ultrafine toner particles in the image forming area. Another object of the present invention is to provide a cleaning blade that can be removed.

[0012]

In order to achieve the above-mentioned object, a cleaning blade according to the present invention contacts a surface of an image carrier of a printer, a facsimile, an electrophotographic copying machine or the like in a counter system, and the image is formed on the image carrier. A cleaning blade for removing toner remaining without being transferred on the carrier surface, and a protrusion is continuously provided at each of both ends of the cleaning blade in contact with a non-image forming area of the image carrier surface, The protruding portion may extend in a counter direction from a position of the cleaning blade in contact with the image forming area on the surface of the image carrier.

Further, it is preferable that both opposing edges inside both of the protruding portions are inclined outward in a C-shape.
More preferably, the configuration can be such that the cleaning blade smoothly transitions along a suitable arc from the contact position of the cleaning blade in the image forming area on the surface of the image carrier to both edges inside the protrusion.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a cleaning blade according to the present invention will be described below with reference to the drawings. FIG.
1 is a perspective view showing a first embodiment of the present invention, and FIG.
FIG. 2 is a sectional view taken along line 2-2 of FIG. Reference numeral 10 denotes a cleaning blade formed by molding a thin plate of neoprene rubber, for example, and is fixed to the holder 12 with an adhesive 14. Adhesive 14
Is exaggeratedly illustrated in black in the drawing.
The photosensitive drum 16 has an image forming area G at the wide center portion defined by the two-dot chain lines a and b, and non-image forming areas N at both ends.
It is. In the drawings and description below, common members are denoted by the same reference numerals.

The cleaning blade 10 has an edge indicated by reference numeral 18 aligned with an appropriate generatrix 20 of the photosensitive drum 16 and comes into contact with the rotation of the photosensitive drum 16 (arrow K in the drawing) in the counter direction. The protruding portions 22 extend in the non-image forming area N on both sides of the drum 16. As shown in FIG. 2, the cleaning blade edge 18 has a contact angle τ with the photosensitive drum 16, that is, the edge surface 19 has a bus line 2.
With respect to the tangent plane T including 0, the surface is pressed in the normal direction (arrow P in the drawing) passing through the bus bar 20 (90 °>) while maintaining an appropriate acute angle exceeding the friction angle α that makes the surface friction coefficient μ tangent. τ> α =
arctanμ).

In the first embodiment, the opposing edges 24 (see FIG. 1) inside both the protrusions 22 are perpendicular to the longitudinal edges 18 and the outside of each edge terminal 26 is adjacent to the adjacent edges 24. It is supported by. Since both the protruding portions 22 form surface contact with the photosensitive drum 16 along both edges 24, "turning" in the image forming area G can be prevented. Such a contact method is, for example, as shown in FIG.
The edge 18 of the cleaning blade 10 that is inclined by a required contact angle τ with respect to a tangent plane T substantially perpendicular to a predetermined normal R of the outer circumferential circle E of the photosensitive drum 16 is separated from the outer circumferential circle E by a distance (two in the figure). (Dotted line) to the center C of the outer circumference circle E along the normal line R.

First, the edge of the cleaning blade 10 is brought into contact with the outer peripheral circle E while the tip of the protruding portion 22 is in contact with the outer peripheral circle E and is deformed to form a surface contact. With a predetermined pressing force. At this time, the edge 24 orthogonal to the edge 18 undergoes deformation along the radius of curvature r1 of the outer peripheral circle E due to the flexibility (or rigidity) of the constituent rubber material, and a part 23 comes into surface contact. FIG. 2B shows a part 23 in an enlarged manner.

Therefore, the edge terminal 26 defining the image forming area G is supported by the projection 22 from the outside,
The protruding portions 22 located in the non-image forming areas N at both ends are in partial surface contact, so that the frictional resistance is reduced even without the presence of toner. As a result, the cause of the “turn-up” at both ends of the cleaning blade 10 disappears. However, in the case of the first embodiment, a gap is formed near the corner portion of the edge terminal 26 because the direction of the stress is discontinuously shifted at the edge terminal 26 between the edge 18 and the edge 24 which are orthogonal to each other. In addition, stress concentration occurs at corners, resulting in poor durability.

FIG. 3 is an enlarged perspective view showing a main part of the second embodiment of the present invention. Opposite edges 34 inside both protruding portions 32 of the cleaning blade 30 are viewed from the front side on the upstream side. It has an outward slope with a "C" shape. That is, since the contact is made in the spiral direction S along the outer surface of the photosensitive drum 16, the radius of curvature r2 of the deformation is larger than in the first embodiment, and the contact area is increased. In addition, since the protruding portion 32 is tapered, an internal stress load required for the deformation that the edge terminal 36 receives is reduced. In addition, since the junction between the edge terminal 36 and the edge 34 becomes an obtuse angle and the stress concentration is relieved, even if the pressing force of the cleaning blade 30 against the photosensitive drum 16 is increased, the edge terminal 36 is not worried about durability. Less, and the reliability of toner removal is improved.

FIG. 4 is an enlarged perspective view showing a main part of the third embodiment of the present invention. In the cleaning blade 40, an arc 43 whose transition from the edge terminal 46 to the edge 44 is gentle (smooth) is shown. Has formed. Therefore, the protrusion 42
Spreads on the surface of the photosensitive drum 16 without difficulty, the surface contact area is further expanded, and the frictional force per unit area is reduced. Therefore, the effect of the pressing force of the cleaning blade 40 on the photosensitive drum 16 on the edge terminal 46 is reduced as compared with the second embodiment in FIG. As described above, the cleaning blades 10, 30, and 40 are
With a very simple configuration of just connecting 2, 42,
The "turn-up" which is a problem in the counter method is reliably avoided without any other modification, and the function of removing the toner is effectively exhibited.

Next, a comparative example of a conventional strip-shaped cleaning blade and the cleaning blade according to the present invention will be described. FIG. 5 shows the specifications of the contact conditions between the cleaning blade 10 and the photosensitive drum 16. That is, a blade having a longitudinal length L = 330 mm, a rubber thickness t = 2 mm, and a rubber free length W = 20 mm in a short direction is used.
The photosensitive drum 16 had a drum diameter D = 100 mm and a rotation speed K = 40 rpm. In these contact modes, the contact bite amount δ = 1 mm, the contact angle τ = 40 °, the contact width f of the protrusion 22 is 5 mm, and the contact length is e = 10 mm.

Test conditions Photosensitive drum 1 before starting the experiment
6. Apply toner. No toner is replenished after the start of the experiment.

Test conditions When the cleaning blade is replaced, the photosensitive drum 16 is also replaced with a new one.

Test conditions 1000 photosensitive drums
The object that rotates and generates “turn-over” during that time is referred to as “turn-over”.

Under the above-described conditions, 10 samples of the cleaning blade with a protruding portion and 10 samples of the strip-shaped cleaning blade were tested. Assuming that the evaluation was “turn-over rate” = (number of turn-overs) / (number of samples), the test results were as follows.

"Rolling rate" of cleaning blade with projections = 0/10 "Rolling rate" of strip-shaped cleaning blade = 3 /
10

As is apparent from the above description, according to the cleaning blade of the present invention, both ends of the cleaning blade which slides on the photosensitive drum in the non-image forming area in the counter system extend in the counter direction. As a result, the toner remaining on the photosensitive drum can be reliably removed without causing "turning" or loss at the end of the cleaning blade.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a first embodiment of a cleaning blade according to the present invention.

FIGS. 2A and 2B are explanatory views taken along line 2-2 of FIG. 1, wherein FIG. 2A is a side view showing the entirety, and FIG. 2B is a partially enlarged view.

FIG. 3 is an enlarged perspective view of a second embodiment of the cleaning blade according to the present invention.

FIG. 4 is an enlarged perspective view of a portion of a third embodiment of the cleaning blade according to the present invention.

FIG. 5 is a schematic view for explaining specifications of an experimental aspect of the cleaning blade according to the present invention.

FIG. 6 is a schematic diagram for explaining a mechanism in which “turning” occurs in a conventional example.

[Explanation of symbols]

 10, 30, 40 Cleaning blade 12 Holder 16 Photoreceptor drum G Image forming area N Non-image forming area 18 Edge 22, 32, 42 Projection 24, 34, 44 Both edges 26, 36, 46 Edge terminal τ Contact angle

Claims (3)

[Claims] 1. A cleaning blade that contacts a surface of an image carrier of a printer, a facsimile, an electrophotographic copying machine, and the like with a counter method, and removes toner remaining without being transferred on the image carrier. A projecting portion is continuously provided at each of both ends of the cleaning blade in contact with the non-image forming area of the image carrier surface, and the projecting portion is
A cleaning blade extending in a counter direction from a position of the cleaning blade in contact with an image forming area on the surface of the image carrier. 2. A cleaning blade according to claim 1, wherein both opposing edges inside both of said projecting portions are inclined outward in a C-shape. 3. A smooth transition along a suitable arc from a contact position of the cleaning blade in an image forming area on the surface of the image carrier to both edges inside the protruding portion. Or the cleaning blade according to 2.