JPS6333708B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cleaning device for a copying machine with an improved cleaning blade.

Conventionally, electronic copying machines are provided with a cleaning device for cleaning toner remaining on the surface of a photoreceptor after transfer. The cleaning device has a cleaning blade made of urethane rubber or the like that comes into contact with the surface of the photoconductor, and removes residual toner on the surface of the photoconductor as the photoconductor rotates.The structure of the cleaning blade is as follows: The one shown in FIG. 1 is known. That is, the device shown in FIG. 1 supports a bracket d to which a blade holding member c is attached on a tangent line passing through the tip of a cleaning blade b in contact with a photoconductor a, and presses the blade b against the photoconductor by a counterweight e. It is configured as follows. However, in this structure, when the pressure contact force of the blade b is set by the weight of the counterweight e, the weight of the counterweight e is determined assuming a large adhesion force of toner, so the pressure on the surface of the photoreceptor is When there is little residual toner or when the adhesion force of the toner is small, the tip of the blade b comes into pressure contact with the photoreceptor more than necessary, causing the tip of the blade b to wear out prematurely.

The present invention has been made for the purpose of improving this problem, and provides a cleaning device for a copying machine in which the pressure contact force of the blade is automatically adjusted according to the frictional force between the surface of the photoreceptor and the tip of the cleaning blade. This is intended to prevent premature wear of the blade without reducing the cleaning effect.

This invention will be explained in detail below with reference to an embodiment shown in FIG. 2 and subsequent figures. In the figure, reference numeral 1 denotes a photoreceptor provided in a copying machine (not shown), which is designed to be rotated in the direction of arrow A, and a cleaning device 2 is installed around the photoreceptor 1. As shown in FIG. The cleaning device 2 has a cleaning blade 3 made of an elastic material such as urethane rubber, and the tip of the cleaning blade 3 touches the photoreceptor 1 from diagonally above.
The proximal end of the cleaning blade 3 is fitted into a groove 5a of a blade holding member 5 fixed to one end of the bracket 4. Bracket 4 is almost square shaped,
The vicinity of the bent portion is rotatably supported by a support shaft 6, and a counterweight 7 for pressing the tip of the cleaning blade 3 against the surface of the photoreceptor 1 is fixed to the other end of the bracket 4.

However, now the support point of the bracket 4 is O, the distance a from this point O to the counterweight 7, the distance b from O to the photoreceptor contact point A at the tip of the blade,
If the angle θ between the line connecting O and A and the tangent to point A of the photoconductor 1, the weight Wg of the counterweight 7, and the coefficient of friction between the blade 3 and the contact portion of the photoconductor 1 is μ, then the vertical direction of the rotating photoconductor 1 The effective contact force P of the blade 3 applied to the
θ……(1) Also, since the contact force P′ of the blade 3 when the photoconductor 1 is stopped is only the component force of the gravity Wg due to the counterweight, P′=a/bWgcosθ……(2) Pressure between both Calculating the ratio P/P′, P/P′=1/1−μcosθ.sinθ……(3
) becomes.

If the horizontal axis represents the friction coefficient μ and the vertical axis represents the pressure ratio P/P', and the angle θ of the blade 3 is varied, a curve as shown in FIG. 4 is obtained. As is clear from this figure, when the pressure ratio is 1, the contact force P always remains unchanged regardless of the frictional force at the contact point of the tip of the blade 3, and when the pressure ratio becomes greater than 1, the contact force P increases as the friction coefficient μ increases. The force P also increases. Therefore, it has been found that the cleaning effect improves as the pressure ratio increases, and as a result of various experiments, it has been found that a pressure ratio P/P' of about 1.3 to 1.5 is good. Further, if the pressure ratio becomes too large, vibrations occur at the tip due to the elasticity of the blade 3 itself, but within the pressure ratio range of 1.3 to 1.5, almost no vibrations occur, and stable cleaning performance was obtained. Furthermore, the blade 3 is made of urethane rubber.
Since the coefficient of friction between the surface of the photoreceptor and the surface of the photoreceptor is usually in the range of 0.4 to 1.0, the optimum angle θ of the blade 3 is 15 to 20 degrees.

As described in detail above, the present invention calculates the angle that a line connecting a contact point and a supporting point of a cleaning blade that is pressed against a photoreceptor by a pressure contact means such as a counterweight makes with a tangent at the contact point of the photoreceptor. 15
By setting the angle in the range of ~20°, the pressure contact force of the blade is automatically adjusted according to the frictional force between the photoreceptor and the tip of the blade. This allows the pressure contact force of pressure contact means such as counterweights and springs to be set small, which eliminates problems such as premature wear of the blade tip due to the blade tip being pressed against the photoreceptor more than necessary, and also reduces friction. As the force increases, the pressing force also increases accordingly, so that even toner firmly adhered to the photoreceptor can be reliably cleaned.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a conventional cleaning device, FIG. 2 is an explanatory diagram of a cleaning device according to an embodiment of the present invention, FIG. 3 is an explanatory diagram of the same operation, and FIG. 4 is a performance curve diagram. 1 is a photoreceptor, 3 is a cleaning blade, 4 is a bracket, 6 is a support shaft, and 7 is a pressure contact means.

Claims (1)

[Claims] 1. In a device that presses the tip of the cleaning blade 3 against the surface of the photoreceptor 1 to scrape off and remove toner remaining on the surface, the cleaning blade 3 is supported swingably on a support shaft 6 by a bracket 4. Attach it to one end of the bracket 4.
A pressure contact means 7 for pressing the cleaning blade 3 against the photoreceptor 1 is provided on the other end side, and a line connecting the support shaft 6 and the contact portion of the tip of the cleaning blade 3 is connected to the photoreceptor contact point of the photoreceptor 1. A cleaning device for a copying machine in which the angle θ with respect to the tangent is set in the range of 15 to 20 degrees.