JPH02168282A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To prevent development in a non-picture area and to reduce the useless consumption of developer by controlling a developing bias voltage in the non- picture area to a voltage value corresponding to the residual potential of a photosensitive body. CONSTITUTION:The developing bias voltage controller 20 of an electrophotographic copying machine is mainly composed of a surface potential sensor 3, a measuring circuit 4, a control circuit 5 and a developing bias power source 6. The control circuit 5 converts a singla into a control signal corresponding to the measuring electric signal, and according to this signal, the developing bias power source 6 applies a developing bias voltage corresponding to the surface potential of the photosensitive drum 1. By such a control means a useless developer is prevented from sticking to the photosensitive drum 1. Consequently, even if the residual potential rises, it is impressed with an appropriate developing bias voltage. Moreover, developing in the non-picture area is prevented, and the useless consumption of developer is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electrophotographic apparatus that outputs different developing bias voltages for image areas and non-image areas of a photoreceptor.

(Prior Art) In general, in an electrophotographic apparatus, during a series of image formation, the image area where an effective image is formed on the photoreceptor is relatively short, and non-image areas before and after the image area account for most of the image formation. It is. In order to reduce the consumption of developer in this non-image area and to prevent the developer from contaminating the inside of the device, various methods have been considered to maintain the non-image area in a non-developed state. There is. One method is to lower the potential of the photoreceptor in the non-image area and set the phenomenon bias voltage to a voltage value that is slightly higher than the potential of the photoreceptor and does not cause the non-image area to be developed. ! There is a way to make it happen.

(Problems that Komei is trying to solve) However, there is a phenomenon in photoreceptors in which the residual potential reaches an upper limit due to optical fatigue. That is, when the photoreceptor is new, the residual potential ranges from around zero to 10% to 20% of the accepted potential.
It is about %. As usage durability progresses, the TATtB potential increases and reaches 30% to 40% or more of the accepted potential, depending on the type 43 of the photoreceptor, exposure conditions, and charging conditions.

If the developing bias voltage of the non-image area is set in advance to a voltage value corresponding to the residual potential when the photoreceptor is in a new state,
When the residual potential increases, the potential difference with the developing bias voltage decreases, causing the problem that non-image areas are also developed.

In addition, if the developing bias voltage of the non-image area is set in advance to a voltage value corresponding to the residual potential that increases as usage durability progresses, it is possible to There was also the problem that non-image areas were developed due to the reversal development phenomenon.

Generally, the developing bias voltage for the non-image area is set to a voltage value intermediate between the two. However, in the case of a photoreceptor with a large increase in residual potential, the non-image area may be developed due to a reversal development phenomenon at the early stage of use and due to the residual potential at the later stage of use.

In conventional electrophotographic devices, the developing bias voltage value in non-image areas is set constant regardless of the increase in the residual potential of the photoreceptor, so development of non-image areas results in unnecessary consumption of developer. There was a problem that this occurred.

In view of the above-mentioned points, an object of the present invention is to provide an electrophotographic apparatus that effectively solves the problems of the prior art, prevents development in non-image areas, and suppresses wasteful consumption of developer. shall be.

(Means for solving the problem) In order to achieve such an objective, Kikomei has developed a residual potential detection means that can detect the potential of 1 J remaining on the photoreceptor, and a non-image detecting means that detects the potential of 1 J remaining on the photoreceptor. The present invention is characterized in that it includes a developing bias voltage control device consisting of a control circuit 611 that controls the developing bias voltage in the region.

According to another aspect of the invention, the residual potential is detected based on the number of times the photoreceptor is used.

According to another aspect of the invention, the residual potential is detected based on the usage time of the photoreceptor.

(Function) With such technical means, the development bias voltage in the non-image area is controlled to a voltage value corresponding to the detected residual potential of the photoreceptor, thereby preventing development in the non-image area, Wasteful developer consumption is reduced.

(Example) Next, an example of the first aspect of the present invention will be explained separately based on the drawings.

FIG. 1 shows a schematic configuration diagram of an embodiment of the present invention. In FIG. J0, a developing bias voltage control device I r! 20 mainly includes a surface potential sensor 3, a measurement circuit 4, a control circuit 5, and a developing bias power supply 6. The surface potential sensor 3 is provided at a pre-processing position of the developing device 2 and detects the surface potential of the non-image area of the photosensitive drum 1.

The measurement circuit 4 converts this surface potential into a measurement electrical signal. The control circuit 5 converts this 1llllllllll constant voltage signal into a control 21I signal. Based on this control signal, the developing bias voltage 6 applies a developing bias voltage corresponding to the surface potential of the photoreceptor drum 1 to the developing device 2 . In addition,
8 is a drum cleaning device, 9 is a charging device, and 1Q is an exposure section.

Such a control means applies a developing bias voltage corresponding to the residual potential in the non-image area of the photoreceptor drum 1, thereby preventing unnecessary developer from adhering to the photoreceptor drum 1. Therefore, even if the residual potential reaches an upper limit, a proper developing bias voltage value is applied, so that the phenomenon in the non-image area is prevented over the entire life of the photosensitive drum 1.

Note that when the photosensitive drum 1 rotates, the developing bias voltage control device 211 always detects the surface potential of the non-image area and controls the developing bias voltage, so the operation can be interrupted in the event of an abnormality such as a jam. Even if the photosensitive drum 1 is restarted with the potential of the image area remaining on the photosensitive drum 1, the developing bias voltage value is controlled to an appropriate value, and the potential remains at 9M, resulting in no development. Consumption of the agent is suppressed.

Next, FIG. 2 shows an outline (M diagram) of another embodiment of the present invention, and FIG. 3 shows a relationship diagram between the residual potential and the number of copies.
In the figure and FIG. 3, the part 38 having the same shield 6B as in FIG. Counter 7, control 21 + circuit 5 and developing bias power supply 6
It consists of The counter 7 (well, it detects the residual potential by measuring the number of rotations (used) of the photoconductor drum 1. As shown in FIG. 3, the residual potential of the photoconductor drum 1 and the number of times it is used.
The relationship between 11 and the number of lightning/exposures (number of copies) is determined by a durability test. The control circuit 5 converts the detection signal from the counter 7 into a preset control signal.

The developing bias power supply 6 applies an appropriate developing bias 73fL corresponding to the control signal of the control circuit 5 to the developing device v12.

The E control device 30 configured in this manner does not require components such as the surface potential sensor +I3 and the JI+I f circuit 4 as shown in FIG. It is possible to apply a current 1p bias voltage within an appropriate range, thereby preventing phenomena in non-image areas and suppressing wasteful consumption of developer.

Alternatively, instead of the counter 7, it is possible to detect the residual potential based on the total usage time of the photosensitive drum 1 by applying a tm meter to measure the rotation time of the photosensitive drum 1. be.

(Effect of Bukoaki) As explained above, according to Kimiaki, there is a residual W potential detection means for detecting the potential remaining on the photoreceptor, and the voltage 11fj corresponding to the residual potential is By providing a control circuit for controlling the developing bias voltage in the image area, the problems of the prior art are effectively solved, development in the non-image area is prevented, and unnecessary consumption of developer is suppressed. gAv of the effects such as being RI-sipped.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram of one embodiment of the present invention, FIG. 2 is a schematic block diagram of another embodiment of the present invention, and FIG. 3 is a diagram showing the relationship between the residual potential and the number of copies. 1: Photosensitive drum, 3: Surface potential sensor, 4: Measuring circuit, 5: Control circuit, 6: Developing bias power supply, 7: Counter, 20, 30: Phenomena bias voltage control device. Figure 1) Figure Patent Applicant Peer Co., Ltd. Company Representative Sotojin Valve J1 Total Yokoya Takeda Diagram Phenomenon Bias Voltage Control 2 to Mushroom

Claims (1)

[Scope of Claims] 1) Among the image area and non-image area of the photoreceptor, the potential of the photoreceptor in the non-image area is set low, and the developing bias voltage applied to the developing device is set to be lower than that of the photoreceptor. In an electrophotographic apparatus, the electrophotographic apparatus is set to a voltage value that is higher than the potential at which the non-image area is not developed, and includes a residual potential detection means for detecting a potential remaining on the photoreceptor, and a voltage value corresponding to the residual potential. An electrophotographic apparatus comprising a developing bias voltage control device comprising a control circuit for controlling a developing bias voltage in a non-image area. 2) The electrophotographic apparatus according to claim 1, wherein the residual potential is detected based on the number of times the photoreceptor is used. 3) The electrophotographic apparatus according to claim 1, wherein the residual potential is detected based on the usage time of the photoreceptor.