JPH0462665B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a charging brush for an electrophotographic device.

(Prior Art and its Problems) Currently, corona discharge is mainly used as a charging method for electrophotographic devices. However, in this method, discharge characteristics are impaired and image quality is degraded due to ozone generation due to discharge and toner and other foreign matter electrostatically adhering to the discharge wire. Therefore, it is necessary to frequently inspect and clean it, and it is difficult for the user to perform this cleaning. Therefore, there is a drawback that so-called operation service costs and maintenance costs are high.

Therefore, as a method to eliminate such drawbacks, a charging method using a brush is proposed, in other words, as shown in the side view of FIG. Using a conductive brush 3 with densely flocked radial bristles, for example, by positioning the brush 3 in contact with the circumferential surface of the photoreceptor 4, which rotates as shown by the arrow in the figure, and rotating it in the direction of the arrow in the figure, charging can be achieved. A method was proposed.

This method eliminates the drawbacks of the corona discharge method and makes maintenance extremely easy, but on the other hand, several new drawbacks arise. For example, one of them is that uneven contact of the brush 3 with the circumferential surface of the photoreceptor 4 and sweeping marks caused by the brush 3 tend to occur, which tends to cause non-uniform charging and deteriorate image quality. Secondly, a force is constantly acting on the tip of the brush bristles 2, which are positioned so as to be in constant contact with the surface of the photoreceptor 4, to bend them along the surface of the photoreceptor 4. For this reason, during continuous use, the tip 2a of the bristles 2 becomes fixed in a bent shape, and as shown in the enlarged partial view of FIG. In addition to this, the bristles 2 forming the brush 3
Since the bending lengths of the tips 2a are uneven due to the uneven lengths of the bristles 2, the contact pressure of the individual bristles 2 to the surface of the photoreceptor 4 changes, and moreover, the bristles 3a are likely to split. As a result, charging tends to become non-uniform, and traces of the brush 3 being bent appear as uneven charging such as white lines on the copied image, resulting in a structural defect that deteriorates the image quality.

Therefore, in order to eliminate such defects, for example, the brush 3 can be rotated at high speed to make the brush strokes less noticeable, or the contact force of the brush 3 to the photoreceptor 4 surface can be reduced to reduce the image quality caused by the position of the photoreceptor. Methods have been proposed to reduce the deterioration, and furthermore, to bring the brush 3 into contact with the surface of the photoreceptor 4 using an electromagnet or a spring body only during copying to minimize the deformation.

However, the method of rotating the brushes at high speeds has the drawback of increasing driving power, increasing wear on the brushes, and further damaging the peripheral surface of the photoreceptor, thereby shortening its life. Furthermore, in order to minimize the contact pressure between the brush and the charged surface of the photoreceptor, it is necessary to uniformly align the bristles of the brush with high precision. For this reason, there is a disadvantage that the yield in manufacturing the brushes is significantly lowered and the brushes become expensive. Furthermore, the method of bringing the brush into contact with the surface of the photoreceptor only during copying is unsatisfactory because it inevitably requires an increase in parts such as an electromagnet, a spring body, and its operation mechanism, which increases costs.

(Objective of the Invention) The present invention has been made for the purpose of providing a charging brush that eliminates the various drawbacks mentioned above, and will now be described in detail with reference to the drawings.

(Means of the Invention for Solving Problems) The feature of the present invention is that the entire length of the bristles 2 of the brush 3 is aligned with respect to the surface of the photoreceptor 4 as shown in the side view of an embodiment shown in FIG. The point is that the so-called beveled hair processing is applied in advance by making it oblique in one direction, and the following method is used for this processing, for example.

That is, a straight-bristle-shaped brush 3 formed by radially implanting linear bristles 2 on the rotating shaft 1 described above in FIG. The bristles 2 are inserted into the pipe 5 while rotating in the same direction as the direction of rotation during the charging operation to align the bending directions of the bristles 2. After that, fix the rotating shaft 1 at both ends of the pipe 5 so that the rotating shaft 1 of the brush 3 is concentric with the pipe 5, so that each bristles 2 have the same shape and are diagonal, and then brush for an appropriate amount of time. A method is adopted in which it is made by being left standing and then being pulled out from the pipe 5.

(Operations and Effects of the Invention) Like the conventional device described above, the brush 3 is positioned so that its tip comes into contact with the surface of the photoreceptor 4, and contact pressure is taken by the elasticity of the bristles 2a that are bent at this time. When the tip 2a of the hair becomes curly due to the constantly applied bending force, the tip 2a
The contact pressure due to the elasticity of a is lost. Moreover, since the bristles 2 are positioned radially, that is, substantially at right angles to the surface of the photoreceptor 4, once the bristles 2a become curly, the elasticity of the straight bristles 2b becomes difficult to work with. Therefore, charging cannot be avoided.

However, as in the present invention, the bristles 2 forming the brush 3
If the beveled bristles are applied to the entire length of the photoreceptor 4 in advance, when the brush 3 is brought into contact with the surface of the photoreceptor 4, the bristles 2 will line up in a line passing through the center of the axis 1 of the brush 3 and the rotation axis 5 of the photoreceptor 4. The bristles 2 are not located on the center line as in the conventional case. Therefore, the contact force is not concentrated only on the bristles 2 as in the conventional case, but is dispersed over the entire length, and the bristles 2 come into contact with the surface of the photoreceptor 4 due to the elasticity of the entire length. For this reason, it becomes difficult for the user to become slouched, and a reduction in the contact pressure to the photoreceptor 4 can be largely prevented.

In addition, since the bristles 2 are oblique to a line passing through the centers of the rotating shafts 1 and 5, the centrifugal force generated by the rotation of the brush 3 acts to bring the bristles 2 into contact with the photoreceptor 4. Therefore, even if the brush and the photoreceptor are placed in a state of zero contact when the brush 3 stops rotating, the bristles 2 come into contact with the charged surface of the photoreceptor 4 when the brush 3 rotates. In addition, fluffing occurs due to the repulsive force of the bristles 2 that become of the same polarity when a charged voltage is applied, and fluffing occurs due to the electrostatic attraction force based on the charged voltage between the brush 3 and the photoreceptor 4. Generates an effect that promotes contact by force. Therefore, if the thickness and elasticity of the bristles 2 are appropriately selected, a contact state can be obtained in which the brush 3 and the photoreceptor 4 are in a zero contact state when the brush 3 is not rotating. Therefore, uniform charging is performed on the surface of the photoreceptor. Furthermore, the beveled hair processing of the present invention is simple and there is no need to align the ends of the hair as in the conventional method, so it can be carried out with almost no increase in cost. Next, an experimental example of the present invention will be explained.

Carbon-containing conductive fibers based on 6 denier rayon with a density of 80,000 fibers/inch ² and an outer diameter of 6
Create a brush with an outer diameter of 18 mm by uniformly planting the hair on a rotating shaft of mm. After inserting this into an aluminum pipe with an inner diameter of 13 mm while rotating in one direction, make sure that the brush and pipe are concentric. Hold and leave it until the outer diameter
We made a 13.2-13.5mm charged brush. Then, this brush was positioned on a drum-shaped organic photoreceptor with an outer diameter of 60 mm so that the distance between the rotating shafts was 36.5 mm (the brush was in pressure contact with the surface of the photoreceptor by 0.1 to 0.2 mm). After leaving it for several months, the rotation speed of the photoconductor drum was increased to 15 rotations per minute, and that of the brush was increased to 135 rotations per minute.
When charged by rotation, it was found that no uneven charging occurred.

On the other hand, the conventional straight-bristle brush described in FIG. 1 was made of the same material, the same thickness, the same bristle density, and the same dimensions as the production example of the present invention, and a charging test was conducted at the same rotation speed. As a result, it was found that uniform charging could not be obtained unless the bristles of the brush were in pressure contact with the surface of the photoreceptor by at least 0.3 to 1 mm. Furthermore, if the brush was left in this state, uneven charging occurred after 24 hours due to the brush's position.

[Brief explanation of drawings]

FIG. 1 is a side view of a conventional charging brush, FIG. 2 is a partially enlarged view thereof, FIG. 3 is a side view of an embodiment of the present invention, and FIG. 4 is a diagram showing an example of a manufacturing method. 1...Brush rotation axis, 2...Brush hair, 2
a... Tip of hair, 3... Brush, 4... Photoreceptor, 5...
…Axis of rotation.

Claims (1)

[Claims] 1. A charging brush for an electrophotographic device in which linear bristles made of a conductive material are radially planted on the circumferential surface of a rotating shaft, characterized in that the entire length of the bristles forming the charging brush is pre-beveled in one direction. A charging brush for electrophotographic equipment.