JPS58198076A - Method for controlling cleaning device of electrophotographic copying machine - Google Patents

Abstract

PURPOSE:To prevent an electrostatic latent image from deterioration and to obtain a stable and fine picture by separating a cleaning brush from the surface of a photoreceptor while contacting the brush with a flicker cover and stopping the rotation of the brush during the copy of plural sheets by one exposure. CONSTITUTION:A supporting arm 7 supporting the cleaning brush 6 pivotally is mounted on the frame of the body through a supporting shaft 13 so as to be freely rotable around the shaft 13. The flicker cover 17 is arranged on a position slightly touching the leading end part of the brush 6 contacted with the surface of the photoreceptor 1. When a solenoid 14 and a brush motor 12 are deenergized at a moment an electrostatic latent image reachs closely to a cleaning part after transferring the 1st picture, the brush 6 is separated from the surface of the photoreceptor 1 by the energizing force of a spring 16 to stop the rotation. Consequently the electrostatically charged potential of the brush 6 is suddenly reduced, so that the electrostatic latent image is almost prevented from deterioration and plural fine pictures are obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is based on an electrostatic latent image once formed on a charge retaining member of an electrophotographic photoreceptor, and is repeatedly developed and transferred to obtain a plurality of copied images. The present invention relates to a method of controlling a cleaning device in sheet copying.

Toner image transfer type electronic copying machines transfer the toner image formed on the charge holding member of the electrophotographic photoreceptor onto recording paper, etc., but it is extremely difficult to completely transfer the toner image. Yes, toner remains on the charge retention member even after the transfer process.This residual toner must be removed from the charge retention member before the next electrostatic latent image is formed.One method is to use a cleaning brush such as a fur brush. ?It has been proposed to remove residual toner by bringing it into rotational contact with the surface of a charge holding member.

1 and 2 show the configuration of a typical electronic copying machine and its cleaning device to which the conventional cleaning method is applied, but the method of the present invention can also be commonly applied.

In FIG. 1, a photosensitive drum 1 is rotatably supported by a copying machine main body frame in the direction indicated by the arrow in the figure. Around this photosensitive drum 1, from upstream to downstream of its rotation, a corona charger 2 for uniform charging is installed. Original image exposure optical system 3. 4. A developing device that forms a toner image from an electrostatic latent image. A transfer roller 5 for transferring a toner image onto a copy paper or the like and a cleaning brush 6 for removing residual toner from the transfer are sequentially arranged along a line parallel to the rotation axis of the photosensitive drum 10, respectively. Further, the cleaning brush 6 is rotatably attached to a pair of support arms 7 that are rotatably supported in the main body room of the copying machine, and is attached to the main body frame of the copying machine except for the portion that contacts the photosensitive drum 1. Fixed housing 8
is surrounded by. A fan 9 is provided inside the housing 8 at a distance from the photosensitive drum 1. Thereby, the housing 8 constitutes a suction duct in the direction of arrow e. Also, between the cleaning brush 6 and 77n 9,
A replaceable filter o is arranged to collect the toner removed from the photosensitive drum 1.

The operation timing of each component related to the copying process, centering on the photosensitive drum 1, is controlled by electrical signals from a control circuit on an electrical circuit board 11 disposed inside the main body of the copying machine. There is.

Next, the configuration of the cleaning device will be explained in more detail with reference to FIG. The photosensitive drum 1 has a charge retention member 1 made of a photoconductor layer containing 8e or a Se-based alloy on the outer peripheral surface of a cylindrical metal base such as aluminum that is electrically grounded.
a, and an electrostatic latent image due to positive charges is formed. The cleaning brush 6 is supported by rotatable support shafts (not shown) provided on each of a pair of supports 7-7, and a brush motor 12 is directly connected to one of the support shafts. By energizing this brush starter 12, the cleaning brush 6 is driven to rotate in one direction of the arrow, and when the brush starter 12 is deenergized, the cleaning brush also stops rotating. Further, the pair of supports 7-m 7 are rotatably attached to the frame of the main body of the copying machine about a support shaft 13 as a fulcrum.

This support arm 7 has a VC1 as schematically shown in the same figure.
The solenoid I4 fixed to the copier body frame is
A tension spring 16, which is engaged via a link 15 and acts in a direction substantially opposite to the operating direction of the solenoid 14, is locked between the main body frame of the copying machine. When the thread/id 14 is energized by these,
℃ against the tension of the tension spring 16, the support 7-m 7 rotates toward the photosensitive drum 1, and when the tension/id 14 is deenergized, the support 7-m 7 is separated from the photosensitive drum 1 by the tension of the tension spring 16. It is configured to rotate in the direction of That is, when the slide/id 14 is energized, the presser brush 6 comes into contact with the outer peripheral portion of the photosensitive drum 1, and when it is deenergized, it is separated from the photosensitive drum 1. The rotation range of the support member 7 is appropriately determined by stoppers (not shown) provided in both directions. Further, below the cleaning brush 6, a metallic seven-point filter bar 17 is disposed parallel to the rotating shaft of the brush at a position slightly touching the tip of the cleaning brush 6 as shown in the figure, and is electrically grounded. When cleaning residual toner, the cleaning brush 6 prevents toner from adhering to or accumulating on the brush.
Cleaning more effectively.

To facilitate this, it is charged to the same polarity as the toner by frictional charging with a flicker bar or the like.

Conventionally, this cleaning device, which uses one-exposure, multiple-copying pressure, has controlled the cleaning device in the following manner. That is, - during exposure multiple copying, solenoid 1 is closed to avoid the negative influence of the cleaning brush on the latent image.
4 to separate the cleaning brush 6 from the photosensitive drum 1. However, in order to simplify the control operation, the cleaning brush 6 continues to rotate in the same manner as during cleaning. In addition, this separation distance cannot be too large in order to prevent the device from increasing in size. Therefore, as mentioned above, the tip of the cleaning brush is charged with the same polarity as the toner, and the tip of the cleaning brush is charged with the same polarity as the toner, and the tip of the cleaning brush is charged with the same polarity as the toner, and the cleaning brush is It has been found that the charged charge of the cleaning brush has an adverse effect on the electrostatic latent image on the photosensitive drum.In other words, charging the cleaning brush to the same polarity as the toner is The polarity becomes opposite, and a strong electric field is generated between the electrostatic latent image on the photosensitive drum and the cleaning brush, causing charge injection and transfer.As a result, the latent image spreads and resolution decreases. Furthermore, the potential of the latent image is reduced, and the electrostatic latent image deteriorates so much that it becomes practically impossible to copy multiple sheets with one exposure.

This invention has been made in view of the above-mentioned circumstances. - A cleaning device that can prevent the deterioration of electrostatic latent images even in exposure copying of multiple copies and obtain stable and high quality copies of multiple copies. Aiming to provide a control method □ The operation of the present invention will be described below with reference to Fig. K2 and Fig. 3. In controlling the cleaning device having the configuration shown in FIG. 2, the present invention provides the following advantages:
The solenoid 15 is deenergized to separate the cleaning brush 6 from the surface of the charge holding member 1a of the photosensitive drum 1, and the brush motor 12 is deenergized to stop the rotation of the cleaning brush 6. An embodiment of this control method will be explained below.

The main motor (not shown) of the copying machine main body that drives the photosensitive drum 1 is energized at time (to), and at the same time
Id 14 and brush Tanabata 12 should also be energized. That is, as the photosensitive drum 10 starts to rotate, the cleaning brush 6 also starts rotating and comes into contact with the outer peripheral surface of the photosensitive drum 1 to start cleaning before the copying operation. Subsequently, as the photosensitive drum rotates 10 times, the electrostatic latent image formed on the charge holding member la of the photosensitive drum 1 is formed on the charge holding member la of the photosensitive drum 1. When the front edge of the front edge approaches the cleaning section (t
At 1), a multiple copying operation is started, and the blade 14 and the brush Tanabata 12 are deenergized. As a result, the cleaning brush 6 is separated from the outer peripheral surface of the photosensitive drum 1, and the rotation of the brush itself is also stopped. In this state, development and transfer are repeated to continue copying the desired number of sheets, and when the leading edge of the electrostatic latent image finishes the final transfer and reaches the cleaning section (t2), it is again shaken/transferred. The idler 14 and the brush motor 12 are energized to perform cleaning after the multiple copying operation is completed. In this state, when a certain amount of time has elapsed (ts), the main Tanabata is deenergized, the slide/id 14 and the brush Tanabata 12 are also deenergized, the rotation of the photosensitive drum 1 is stopped, and the cleaning grating is deenergized. The white is separated from the outer circumferential surface of the photosensitive drum 1 and rotation is also stopped, completing a series of copying operations. In addition, in this example,
As shown in Figure 3, the timing of Tsure/Ido and Brush Tanabata were the same. However, when the cleaning brush is in contact with the photosensitive drum, in order to ensure a predetermined rotation speed of the brush, the timing of the twist/idle is changed (to, t2) when the cleaning brush is in contact with the photosensitive drum.
) - slightly delayed, and when separating the brush from the photosensitive drum (tl, ts), it may be slightly accelerated. Further, in this embodiment, a cleaning process is provided before and after a plurality of copying operations, but either one of the cleaning processes may be omitted.

Next, the present invention will be explained based on a specific embodiment and compared with a conventional example as shown in FIG.

Experimental example (1) Fabric made by flocking rayon fibers with single fibers of about 10 denier at a density of about 10,000 fibers per square inch as an SO-based photoconductor cleaning plan on the charge retention member of the photosensitive drum. is wound around a paper tube with an outer diameter of about 60 cm and a length of about 14 hairs. If the cleaning brush is moved approximately 211 degrees away from the photosensitive drum and the rotation of the brush is not stopped, the cleaning brush will move as shown in Figure 4 ■-A.
It was charged to -300V like this. For this reason, approximately 400V
An electric field of about 1,200 V is generated between the electrostatic latent image made of positive charges and the cleaning brush, and each time the latent image on the photosensitive drum passes through the cleaning section, it is affected by the above-mentioned adverse effects. As a result, it deteriorated significantly, making it practically impossible to make multiple exposure copies.

On the other hand, in this invention, when copying multiple copies by exposure, if the cleaning brush is separated from the photosensitive drum and its rotation is stopped, the charged potential of the brush decreases rapidly as shown in Fig. 4-B. , became HaboOv. and,
In this case, the deterioration of the electrostatic latent image was extremely small, and good images obtained by copying multiple copies of one exposure were obtained.

Experimental example (ff) The material of the cleaning brush was conductive rayon fiber (10
3Ω・m to 10Ω・on), and the rest are experimental examples (I).
When comparing the conventional example and the present invention in the same manner as in Figure 4g-A, in the conventional example, the cleaning plan was charged to -6O0V, and the electrostatic latent image was not formed as in Experimental Example (1). Significantly deteriorated. However, when this invention is applied, the charging potential of the brush becomes as shown in the experimental example (I) as shown in the same figure...-B.
In this case as well, almost no deterioration of the electrostatic latent image was observed and a plurality of good copies were obtained.

Note that the charging potential of the cleaning brush shown in FIG. 4 was measured by placing an electrometer at a position on the outer peripheral surface of the photosensitive drum facing the brush.

The present invention is not limited to the method of controlling a cleaning device having the above-described configuration. You can also use your body.

As explained above, according to the present invention, the potential of the cleaning plan can be maintained at approximately Ov during one-exposure copying, and the electrostatic latent image on the charge retention member is prevented from deteriorating and stabilized. Good quality multi-copy images can be obtained.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a schematic sectional view showing an example of an electronic copying machine having a leaning device to which the present invention can be applied, and FIG.
FIG. 3 is a diagram showing an example of the operation timing of the cleaning device according to the present invention, and FIG. 4 is a characteristic diagram showing the results of experimental examples using the present invention and the conventional method. It is. 1...Photosensitive drum 6...Cleaning brush 7...Support arm 12...
Brush motor 4...Tsure/id 16...
...Tension spring 17...-Flicker bar 5□

Claims (1)

[Claims] In a cleaning device for an electronic copying machine that repeatedly performs development and transfer based on an electrostatic latent image once formed on a charge retention member of an electrophotographic photoreceptor to obtain a plurality of copied images, the charge retention member When cleaning the member, the cleaning brush is rotated and brought into contact with the charge retaining member and the conductive flicker bar, and during multiple copying, the cleaning brush is kept in contact with the pricker bar while the cleaning brush is rotated. A method for controlling a cleaning device for an electronic copying machine, characterized in that 1.