JPH01124877A - Conductive brush for electrostatic charging device of electrophotographic recorder - Google Patents

Abstract

PURPOSE:To economize the conductive brushes by arranging two brushes made of napped conductive fiber materials on a substrate with flat surfaces successively in the rotating direction of a drum. CONSTITUTION:A conductive brush 10' consists of two independent and separate parts 13 and 14 and are installed successively in the rotating direction of the drum 1 and in parallel to each other. The brushes 13 and 14 have narrow width W1 and W2 respectively, so even when the surfaces of the substrates 13' and 14' are flat, the tip of the conductive fiber 12 and the surface of the drum 1 come into contact with each other. Then the brushed 13 and 14 are made individually replaceable by using bellows type housing, etc., and the replacement of only the front brush 13 is facilitated. Consequently, the manufacture and replacement of the brushes are facilitated.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to an improvement in the brush mechanism of a conductive brush charging device used in electrophotographic devices such as copying machines and printers, which is easy to manufacture and easy to replace in case of contamination. A brush of a conductive brush charging device for the purpose of forming a brush in a conductive brush charging device, the brush of the conductive brush charging device being installed so as to be in contact with the surface of a rotating photoreceptor drum, and for uniformly charging the surface of the drum. It is manufactured by being divided into two or more parts in the front and back in the direction of rotation, and each part is made of conductive fibers flocked on a substrate with a flat surface, and the parts are configured to be replaceable independently of each other. do.

[Industrial application field]

The present invention relates to a conductive brush charging device used in electrophotographic devices such as copying machines and printers, and particularly relates to improvements in the brush mechanism of the charging device.

[Conventional technology]

In electrophotographic recording devices, corona dischargers were once exclusively used to charge recording media such as photoreceptor drums, but these corona dischargers have a power of several kV to 1 Qkv.
This requires a relatively high voltage and a considerable amount of space in order to stably cause corona discharge, which is one of the bottlenecks in reducing the size of the entire device.

Therefore, in order to miniaturize the device, many conductive brush charging devices have been proposed, in which a constant voltage is applied to a conductive brush using bristles made of conductive fibers, and the brush is brought into contact with a photosensitive drum to charge the photosensitive drum. ing.

A typical mechanism of the latter type of electrophotographic recording device is shown in FIG. 6. A conductive brush charging device 2 is provided in a part of the periphery of the photosensitive drum l which rotates at a constant speed. By contacting the surface of the drum 1, the drum 1 is charged, for example in a negative manner. Next, the drum 1
The exposure device 3 applies a desired image to the surface of the substrate using a laser beam or the like. The photoreceptor that makes up the surface of the drum 1 is insulative in the dark, but becomes conductive when exposed to light, so the electric charge in the area exposed to the light is neutralized and a latent image corresponding to the image is generated. An image is obtained on drum 1. For this image, a bias voltage is applied to the developing roll so that the potential of the developing roll is negative with respect to the potential of the exposed latent image.
When a toner made of negatively charged carbon powder C or the like is applied only to the exposed areas, the toner adheres to the drum.

In the area next to the drum 1, a sheet 4 is running in contact with it, and a corona charger 5 is provided below the drum 1 through the paper sheet 4, and a corona charger 5 is installed on the underside of the drum 1 through the paper sheet 4. Charge it to ten. Therefore, the charged toner powder adhering to the image on the drum 1 is attracted by this and transferred onto the cover sheet 4. Thereafter, the paper sheet 4 is sandwiched between a heating roll 6 and an elastic roll 7 in contact with the heating roll 6 to fix the toner on the surface, resulting in a desired hard print.

On the other hand, in the next area, the drum 1 is entirely exposed to light by the static eliminator 8 to remove the remaining charge, and then is cleaned of the remaining toner powder by contact with the cleaner 9, and is again exposed to the conductive brush charging device 2. The above operations are repeated under the influence of .

As mentioned above, this type of copier can be miniaturized, but it requires a certain amount of contact time between the brush and the drum to charge the drum to the required potential, and in order to ensure this time, is a continuously rotating drum l as described above.
The tip of the brush of the charging device 2 that comes into contact with the drum is required to have a concave surface with a constant width so as to be in close contact with this surface along the rotational direction of the drum.

[Problem that the invention seeks to solve]

Conventionally, in order to obtain such a shape of the brush 10, the seventh
As shown in the figure, a substrate 11 made of a fairly thick aluminum plate is cut to form a concave surface that matches the curved surface of the drum L, and a pile fabric or the like having conductive fibers 12 flocked thereon is pasted. However, this method was not suitable for mass production, and the processing costs were high, contributing to the rise in manufacturing costs.

Furthermore, another problem is contamination of the brush. That is, this brush 10 tends to be contaminated by residual toner on the drum that has not been completely cleaned by the cleaner 9, and in particular, the brush area A on the side that receives the drum 1 when viewed from the rotational direction is extremely contaminated. The present inventor used the recording apparatus shown in FIG. 6 to measure the degree of brush contamination when recording was repeated as an increase in the electric resistance value of the brush. FIG. 8 shows a graph in which the results are plotted against the distance from the leading edge of the brush having a width of 15 mm. According to experience, it has been found that when the electrical resistance reaches l♂, the charging property of the drum is adversely affected. According to this graph, after 3000 sheets have been output, the resistance of 1/3 of the front area of the brush increases to the critical resistance.
After 5,000 sheets were output, 1/2 of the area rose to critical resistance. Such contamination of the brush reduces the effective width of the brush and impedes the uniform charging action on the drum, so when the contamination reaches a certain limit, the brush itself must be replaced with a new or cleaned brush. . However, it is undesirable to replace all of the wide and expensive brushes as described above even if only a part of them becomes contaminated, as this increases the cost.

[Means for solving problems]

The present invention aims to solve the problems of the prior art, and provides a brush configuration in a conductive brush charging device that is easy to manufacture and easy to replace in case of contamination.

That is, the present invention provides a brush for a conductive brush charging device that is installed so as to be in contact with the surface of a rotating photoreceptor drum and is used to uniformly charge the surface of the drum, the brush being installed in contact with the surface of a rotating photoreceptor drum, the brush being arranged to uniformly charge the surface of the drum. Manufactured by dividing into two or more parts, each divided brush is made of conductive fibers flocked on a substrate with a flat surface, and the divided brushes are configured to be replaceable independently of each other. Provides a conductive brush featuring:

The frontmost divided brush installed at least on the side facing the drum with respect to the rotating direction of the drum is configured to be freely stored in a bellows-type housing installed on the side of the drum when replacing the brush. is desirable.

[For production]

The brush of the conductive brush charging device of the present invention is composed of two or more parts each having a relatively narrow width in the front and back directions, so the frontmost part is particularly contaminated during use and requires frequent replacement. It becomes possible to replace only the divided brushes independently from the rear part. In addition, since each part is configured as a brush with a relatively narrow width, even if the substrate is made flat, there will be no substantial adverse effect on the contact state with the photoreceptor drum, making it easy to manufacture. Costs are low.

In addition, since a bellows-type housing is provided on the side of the front split brush so that it can be stored, when replacing the brush, the brush can be moved laterally across the drum, and as the brush moves, the The bellows housing can be extended to accommodate the brush without exposing it. This prevents the toner adhering to the brush from scattering around and polluting the environment.

〔Example〕

Hereinafter, the present invention will be explained in more detail based on preferred embodiments shown in the drawings.

FIG. 1 shows an example of a split conductive brush of the present invention in a conductive brush charging device 2 attached to a photosensitive drum 1. As shown in FIG. Other parts have been omitted but are arranged substantially in the same manner as in the conventional apparatus described in connection with FIG.

The conductive brush 10'' of the present invention is composed of two parts 13 and 14 that are arranged in parallel in front and back relative to the rotational direction of the drum 1 and are independent and separated from each other. Each part 13
．． 14 has a width W narrower than that of the conventional brush 10 described above.
1 and W2. Therefore, each substrate 13
The surfaces of ' and 14' are not pre-formed into a concave shape that is complementary to the surface of the drum 1 as in the case of conventional brushes, but are flat surfaces, but the conductive fibers constituting the brush body are 12 and the surface of the drum 1 can be obtained.

According to the research of the present inventor, in order to obtain close contact between the conductive fibers 12 and the surface of the drum 1, it is necessary to It is desirable that the distance S to the surface is about 0.5 mm shorter. Further, the total width of the preferable divided brushes 13 and 14 is as follows: fiber 1
2 and the distance S, for example, L
is 5 dragons.

If S is 4 m and the diameter of drum 1 is 60 m, then 2
Approximately 0 cranes is preferable.

The subdivision brushes 13, 14 are constructed so that they can be removed and attached separately. As mentioned above, it is clear that the brushes are more heavily soiled in the front region, and therefore the divided brushes 13 located at the front need to be replaced more frequently.

Regarding this, in the example of FIG. 1, the divided brushes 13 and 14 are configured to have approximately the same width, but as shown in FIG. 2, the width W1 of the divided brush 13 installed in the front
It is preferable to make the width W2 smaller than the width W2 of the divided brush 14 installed at the rear. Here, "front" and "rear" refer to the direction of rotation of the drum l, and the direction that reaches the drum surface earlier is referred to as the front, and the direction that reaches the drum surface later is referred to as rear. The reason for arranging it in this way is that, as mentioned above, the degree of dirt on the brush is much higher in the front part 13, and therefore the wear rate is also higher. This is because it is a good idea to reduce production costs.

In the above example, the brush 10' is divided into two parts 13.1 and 13.1, the front and rear parts.
Although the brush is divided into four parts, the number of divisions is not limited to this, and it is also possible to configure the brush with three or more parts and change the replacement frequency sequentially.

A problem that arises when replacing the brush is that when the brush is removed, the toner adhering to the bristles of the brush scatters and contaminates the surrounding environment. Therefore, as a countermeasure against this problem, the following is proposed as a preferable embodiment of the present invention.

According to this, each divided brush 13, 14 (hereinafter represented by 13) is integrally constructed with a housing 16 installed at one end thereof. That is, as shown in FIGS. 3 and 4, the housing 16 is connected to the base plate 13'' of the divided brush 13.
has a cap 17 fixed to one end of the frame 17, and a bracket 18 that can be detachably attached to the frame 15 of the machine as described later. It is equipped with a flexible bellows 19.

When the bellows 19 is retracted, the bellows 19
is stored in the cap 17, and the conductive fibers 1 of the brush are stored in the cap 17.
The part of the hair consisting of 2 is completely exposed. On the other hand, the dimensions are designed such that when the bellows 19 is extended, the bristles of the brush are completely covered by the bellows 19, as shown in FIG.

When in use, this divided brush 13 is attached to a predetermined location on one side frame 15 of the machine stand, as shown in FIG. That is, the housing 16 is located outside the frame 15, and the main body of the split brush 13 is installed so as to extend into the working area of the drum l through the opening 20 provided in the frame 15. This position is fixed by engaging the bracket 18 with the mounting unit 21 of the frame 15. In this state, the bellows 19 is contracted and housed within the camp 17.

When removing the divided brush 13, the divided brush 13 is moved to the left in the figure through the opening 20. Accordingly, the bellows 19 gradually expands and completely covers the divided brush 13 protruding from the frame 15. Therefore, even if the toner powder adhering to the bristles of the brush that has come out of the system falls off, it is blocked by the snake 1tl19 and will not be scattered around, thereby preventing environmental pollution.

Finally, the state is similar to that shown in Figure 4, and frame 1
removed from 5.

〔Effect of the invention〕

As described in detail above, the brush of the conductive brush charging device of the present invention is composed of two or more parts each having a relatively narrow width in the front and rear directions, so it is particularly contaminated during use and requires frequent replacement. It becomes possible to replace only the frontmost segmented brush that requires the same amount of time, independently of the rear part. In addition, since each part is configured as a brush with a relatively narrow width, even if the substrate is made flat, there will be no substantial adverse effect on the contact state with the photoreceptor drum, making it easy to manufacture. Costs are low.

In addition, since a bellows-type housing is provided on the side of the front split brush so that it can be stored, when replacing the brush, the brush can be moved laterally across the drum, and as the brush moves, the The bellows housing can be extended to accommodate the brush without exposing it. This prevents the toner adhering to the brush from scattering around and polluting the environment.

[Brief explanation of the drawing]

Fig. 1 is a side view of an example of the split type brush of the present invention in an operating state, Fig. 2 is a side view of another example, and Fig. 3 is a side view of the brush with a housing of the present invention when contracted. , FIG. 4 is a side view when the brush is extended, FIG. 5 is an enlarged side view showing how the brush with a housing is installed, and FIG. 6 is a side view showing the configuration of a copier equipped with a conductive brush charging device. FIG. 7 is a side view of a conventional brush in an operating state, and FIG. 8 is a graph showing the degree of dirt on the brush. DESCRIPTION OF SYMBOLS 1... Photosensitive drum, 2... Brush charging device, 3... Exposure device, 4... Paper sheet, 5...
...Corona charger, 6...Heating roll, 7...
Elastic roll, 8... Static eliminator, 9... Cleaner, 10.10°... Brush, 11...
・Substrate, 12... Conductive fiber, 13.1
4-...Divided brush, 15...Frame, 16...Housing,
17... Cap, 18... Bracket for installation, 19... Bellows, 20... Opening, 21...
・Installation is a unit.

Claims (2)

[Claims] (1) A brush (10') of a conductive brush charging device (2) installed in contact with the surface of the rotating photoreceptor (1) to uniformly charge the surface of the photoreceptor (1). and two or more parts (1
Each divided brush (13, 14) is manufactured by dividing it into two parts (13', 14) each having a flat surface.
') A conductive brush comprising conductive fibers (12) flocked thereon, wherein the divided brushes (13, 14) are configured to be replaceable independently of each other. (2) With respect to the rotational direction of the photoreceptor (1), the frontmost divided brush installed at least on the side facing the photoreceptor (1) is (13
), the conductive brush according to claim 1, wherein the brush is configured to be freely stored in a bellows-type housing (16) installed on the side of the photoreceptor (1) when replacing the brush. brush.