JPS63313184A - Cleaning device for electrophotography - Google Patents

Abstract

PURPOSE:To improve cleaning performance even for a fast photosensitive body by applying specific biases to a conductive brush and a conductive roller which constitute a cleaning device and setting the difference between the voltages to <=+ or -300V. CONSTITUTION:Residual toner on a photosensitive body 1 which is charged electrostatically by an charger to the negative polarity moves onto the conductive brush 6a which is biased to the opposite polarity from the toner and further passes the conductive roller 6a which is biased, and is scraped off by a blade 6c. The brush 6a is applied with >=100V and the roller 6a is biased to <=300V, thereby setting the difference between the both to <=300V. Consequently, the cleaning performance can be improved even for the fast photosensitive body.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a cleaning device for electrophotography, and is applicable to FAX and printer technology.

[Prior art]

Conventionally, in an electrophotographic cleaning device, there has been a method for removing residual toner on a photoreceptor using a conductive brush (Japanese Patent Application Laid-open No. 54-87232), and a means for removing residual toner on a photoreceptor using a soft roller. Means for removing attached toner by applying a voltage corresponding to the charge of the toner to a conductive roller (Japanese Patent Laid-Open No. 49-91651,
JP-A-53-11030) is publicly known.

However, these means have insufficient cleaning performance and are not particularly useful as cleaning devices for high-speed machines, and none have been put into practical use.

[Purpose of the invention]

The present invention provides an electrophotographic cleaning device having a conductive brush, a conductive roller, and a scraping member, which is equipped with a cleaning bias condition that improves cleaning performance compared to the conventional cleaning device described above, Another object of the present invention is to provide a cleaning device that can be fully used in actual high-speed machines.

[Structure of the invention]

In order to achieve the above object, the present invention provides a conductive brush that is in contact with an image carrier and is applied with a bias having a polarity opposite to that of the residual toner on the image carrier; In an electrophotographic cleaning device including a conductive roller to which an electric conductive voltage is applied and a member in contact with the conductive roller, a bias applied to the conductive brush is 100 V or more (Vm, i>100 V) and a bias is applied to the conductive roller. bias below 300V (Vm, * < 300V)
, the difference between brush bias and roller bias is ±300V.
range (300V<VB,B VB,ll<300
The present invention is characterized in that it includes means for applying voltage according to the three conditions of V).

Examples of the present invention will be described. FIG. 1 shows an example of an electrophotographic apparatus to which the cleaning device of the present invention can be applied, in which an Se-based photoreceptor drum 1 is charged with a charger 2 powered by a DC power source, and an optical image 3 of an original (not shown) is charged. θ is exposed by the developing sleeve 4a of the developing device 4.
Developing toner with an electric charge is supplied. Next, the developed toner on the photoreceptor drum 1 is transferred to a transfer paper by a transfer charger 5 powered by a DC power source, the residual toner on the photoreceptor drum 1 is cleaned by a cleaning device 6, and the toner removed by a static elimination charger 7 powered by a DC power source is then removed. The charge is removed, and the photosensitive drum 1 rotates to the next image forming cycle. Note that 9 is an eraser, 10 is a pre-transfer charger, 11 is a separation charger, and 12 is a static elimination lamp.

In the present invention, a pre-cleaning charging chamber 8 is provided in front of the cleaning device 6, and the photosensitive drum 1 and residual toner are charged to O. In this case, the linear velocity is 370
When a charger is applied to the photosensitive drum 1 of w/sec with a DC component of -1.6 μA/cvs and an AC component of 4 μA/elm during pre-cleaning charge 8, the drum potential becomes -150 to -400V.

The cleaning device 6 is in contact with the photoreceptor drum 1 in a direction opposite to the rotating direction thereof, and is made of conductive fibers such as 5A-7 made by TORAY for moving the toner on the surface of the photoreceptor drum 1 (hereinafter referred to as a conductive brush). brush) 6a and conductive brush 6
A conductive roller 6b contacts the conductive roller 6b to move the toner on the conductive brush in a direction opposite to the rotating direction of the conductive roller 6b, and a blade 6c contacts the conductive roller 6b to scrape off the toner on the electrosensitive roller. We are prepared.

The residual toner on the surface of the photoreceptor drum 1, which has been charged to θ during pre-cleaning charging step 8, is transferred from the photoreceptor drum l when it passes through the conductive brush 6a to which a bias opposite to the polarity of the toner is applied. The toner on the conductive brush 6a moves to the conductive roller 6b to which a bias is applied, and the toner is scraped off by the scraping blade 6C, and the toner is removed from the surfaces of the conductive brush 5a and the conductive roller 6b. are kept clean at all times.

The present invention provides a conductive brush 6a in a cleaning device.
It was confirmed that the cleaning performance was improved by applying a predetermined bias condition to the IX electroconductive roller 6b.

The graph in Figure 2 shows the brush bias (VB, B),
This shows the relationship between the cleaning performance of residual toner, and if the brush bias (vm, a) is less than 100 square meters, satisfactory cleaning performance cannot be obtained.

The graph in FIG. 3 shows the relationship between the roller bias (VII, R) and the toner that adheres to the background portion (portion without residual toner) on the photosensitive drum after passing through the conductive brush. Roller bias (Va, ++) below 400V,
Preferably, by setting it to 300 .mu. or less, the amount of toner adhering to the photoreceptor drum can be minimized. If there is toner adhering to the background area, it will appear as a background stain copy during the next image forming process.

Fig. 4 shows the relationship between the difference between the brush bias and roller bias (Va6m VB, R) and the cleaning performance of residual toner, and the optimum (VB, Il V3.8)
I was able to know.

Conventionally, it has been considered that the roller bias is larger than the brush bias (Va, a < Vll, R) as a condition for good residual toner cleaning performance, but as can be understood from this graph, in the present invention, the roller bias Bias (VB
, R) was 300 V or more higher than the brush bias (Vm, s) (VB, l VB, R < 300 V), it was confirmed that the cleaning performance deteriorated.

Furthermore, in the present invention, when the brush bias (vg, m) and the roller bias (Vm, *) are equal (V m, s=
■3. R), when the brush bias (vm, m) is higher than the roller bias (■ irises, R) (V+, s > VB.

R), it was confirmed that the cleaning property was good.

In this case of VB,B >Vm,R, the difference between the brush bias and roller bias (VB,ll VB,Il
) is required to be 300V or less.

If the difference between the brush bias and roller bias is 300V or more, cleaning problems are thought to occur because the charge flowing between the conductive brush and the 4-volt roller changes the polarity of the toner to be moved. .

〔Effect of the invention〕

The present invention provides a conductive brush and a conductive roller in a cleaning device with predetermined bias conditions, thereby eliminating the need to apply high voltage or high current bias to the photoreceptor drum of a high-speed machine. It also has the effect of good cleaning performance.

[Brief explanation of drawings]

Fig. 1 is a schematic explanatory diagram of an electrophotographic apparatus to which the cleaning device of the present invention is applied, Fig. 2 is a graph showing the relationship between brush bias (Vtr, t) and residual toner cleaning performance, and Fig. 3 is a graph showing the relationship between brush bias (Vtr, t) and residual toner cleaning performance. A graph showing the relationship between (Vm,,) and toner adhering to the background. Figure 4 shows the difference between brush bias and roller bias (VB,
! 4 is a graph showing the relationship between cleaning performance of residual toner and IVB,R). 6... Cleaning device, 6a... Conductive brush,
6b... Conductive roller, 6c... Scraping member. Patent Applicant Ricoh Co., Ltd. -@ Figure 1 72-'' Ips (Vs, e) 72-'' Ips (VB, R) Figure 3 Vs, s -Vs, R

Claims (1)

[Claims] a conductive brush that is in contact with the image carrier and is biased to have a polarity opposite to that of the residual toner on the image carrier; a conductive roller that is in contact with the conductive brush and is biased; In an electrophotographic cleaning device comprising a member in contact with the roller, the bias applied to the conductive brush is 100V or more (V_B_,_B>100V), and the bias applied to the conductive roller is 300V or less (V_B
_, _R<300V), the difference between the brush bias and roller bias should be greater than -300V, but not higher than 300V (-300V<V_B_, _B-V_B_, _R
1. An electrophotographic cleaning device characterized by comprising means for applying voltage under conditions of <300V).