JPH0212277A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To detect abnormality and dirt of chargers by comparing the output of a surface potential sensor to a reference value and a reference range by a control means. CONSTITUTION:The surface potential of a drum 1 is detected by the surface potential sensor 3 during a copying operation, and the data thereof are sent to a CPU 9 wherefrom a control signal is sent to a high-voltage unit 7 so that the potential of a drum surface by electrostatic charge applied by a main charger thereto is maintained constant. The abnormality in the chargers 2 and 6 is detected before the copying operation by this surface potential sensor through the use of the output thereof prior to the copying operation. The output obtained from the surface potential sensor 3 during warming up is led to the control means without being changed, and compared with a prescribed reference value. Based on comparison with the reference value, it is judged whether the chargers are normal or there is failure, and whether the output is within a prescribed range or not so that the dirt is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to electrophotographic devices such as electronic copying machines and printers.

Although the present invention is not limited to electronic copying machines, the following description will use electronic copying machines as an example.

In an electronic copying machine, corona discharge is generated in the main charging section that charges the photoconductor, the transfer section that transfers the developed image formed on the photoconductor onto paper, and the separation section that separates the transferred paper from the photoconductor. A charging device is required. This charging device consists of a charge wire, a shield case with a U-shaped cross section that shields the charge wire, and a support part on which the charge wire is stretched. By the way, dust and dirt in the air tend to adhere to the charge wire's surrounding surface.
Since charging unevenness occurs, it is necessary to perform cleaning from time to time.

Therefore, as a premise, it is necessary to know that the charger is dirty, but conventionally, the only way to know whether the charger is dirty is to look at the copied image and judge it from the image quality. Ta. In addition, the charger may experience failures such as disconnections or short circuits, and the high-voltage unit that supplies high voltage to the charger may also fail, but these failures are detected by the high-voltage unit, and a dedicated C of the microcomputer through the alarm wire
This was done by informing the PU.

However, with this method of notifying the control unit of a failure in the charger etc. from the high voltage unit through a dedicated alarm line, the number of signal lines connecting the control unit and the high voltage unit increases and The number of circuits increases, which increases costs.

Moreover, an increase in the number of wiring lines is undesirable from the viewpoint of reliability.

On the other hand, regarding the detection of dirt on the charger, the visual Ly! However, the method of doing it based on knowledge is very inconvenient.

The present invention has been made in view of these points, and provides an electrophotographic device that can detect a failure in a charger or the like without providing a dedicated signal line or circuit, and an electrophotographic device that can electrically detect dirt on a charger. The purpose of the present invention is to provide an electrophotographic device that has the following features.

1. In order to detect a failure of the charger, etc., the present invention has the following functions:
In an electrophotographic apparatus that includes a charger system that charges the surface of a rotating body on which a photoreceptor is arranged, and a surface potential sensor that detects the surface potential of the rotating body, the surface potential is determined during warm-up before electrophotographic operation. The charger system is configured to include a control means for detecting an abnormality in the charger system by comparing the output of the sensor with a predetermined reference value.

In addition, in the present invention, in order to detect dirt on the charger,
A charger that charges the surface of a rotating body with a photoreceptor placed thereon;
In an electrophotographic apparatus including a surface potential sensor for detecting a surface potential of the rotating body, it is determined whether an output of the surface potential sensor is within a predetermined reference range during warm-up before an electrophotographic operation. The charger is configured to include a control means for detecting dirt on the charger.

In an electrophotographic apparatus having a charger abnormality detection function with such a configuration, the output obtained from the surface potential sensor during warm-up is directly led to the control means, where it is compared with a predetermined reference value. be done. Then, it is determined whether it is normal or malfunctioning based on the comparison with the reference value.

Further, in the electrophotographic apparatus having the function of detecting contamination of the charger having the above-described configuration, it is determined whether the output of the surface potential sensor is within a predetermined range, and contamination is detected based on this determination.

fruit n Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing the main parts of an electronic copying machine embodying the present invention, and (1) is a rotating drum having a photoreceptor disposed on its surface, which rotates in the direction of the arrow. A main charger (2), a surface position sensor (3), a selfoc lens (4), an exposure lamp (5), and a transfer charger (6) are installed around this rotating drum (1) along the rotation direction. Provided in order °ζ. Of course, other components such as a developing device, a separation charger, and a static elimination lamp are arranged around the rotating drum (1), but to simplify the illustration, these components are omitted. There is.

(7) is a high voltage unit, which applies high voltage to charging devices such as the main charger (2) and transfer charger (6) based on the control signal 411 given from the CPU (9) through the ■10 port (8). Provide voltage. The original purpose of the surface potential sensor (3) is to detect the surface potential of the drum (1) during the copying operation and transfer the data to the CPU.
(9) and from the CPU (9) to the high voltage unit (
7) to keep the potential on the drum surface constant due to the charging applied from the main charger or the like by sending a control signal to the drum. However, in this embodiment, the output of the surface potential sensor before the copy operation (that is, during warm-up) is used to control the charger (2) (
6) abnormalities (including abnormalities in the high voltage unit) are detected. Also, dirt on the charger is detected in the same way.

The detection operation is performed by the CPU (9), and the operation will be explained with reference to the flowchart shown in FIG.

First, in step (!l), the motor is turned on to rotate the rotating drum (1), and the main charger (2) and exposure lamp (5) are turned on.
2), wait for X seconds to pass, and then press C in the next step (13).
The PU (9) reads the output value of the surface potential sensor (3). The y seconds are selected to be a sufficient time for the charged surface of the drum (1) to face the surface potential sensor (3). The starting point is the start of the ON operation in step (II). Note that both this y seconds and y seconds, which will be described later, are executed by a timer counter in the microcomputer including the CPU (9).

The CPU (9) compares the value read in the step (113) with the data preset in the ROM (lω) in the next step (114).This data indicates that the main charger (2) is abnormal (therefore, the main charger (2
) or a failure of the high voltage unit (7)).Specific examples are 600V and 1000V, that is, 600V or less or 100OV or more. If so, it is determined that some kind of defect has occurred in the main charger (2) or the high voltage unit (7). Therefore, if it is not between 600 V and 100 OV (i.e. outside the range), step (11
0), the motor, main charger (2), and exposure lamp (5) are all turned off, then abnormality processing is performed in step (111), and the process returns. Here, the abnormality processing may include indicating an abnormality using a lamp or sound.If the voltage is between 600 V and 1000 V (within the range) in step (114), it is determined that there is no abnormality and the process proceeds to step (15). .

Step (115) and subsequent steps are the flow for detecting whether the transfer charger (6) is abnormal, that is, whether there is a defect in the transfer charger (6) or the high voltage unit (7). The high voltage unit (7) is connected to the main charger (
The high voltage supply system to the transfer charger (2) and the high voltage supply system to the transfer charger (6) are different.
) If there is a defect in the high voltage supply system, this flow will detect it.

In step (15), turn off the main charger (2)
In the 0th step (116) of turning on the transfer charger (6) at the same time, after the transfer charger (6) is turned on, the portion charged by the transfer charger is placed in a sufficiently large area facing the surface potential sensor (3). chosen at the time.

After waiting y seconds in step (I6), the CPU (9) reads the output value of the surface potential sensor (3), and then compares this output value with the data previously stored in the ROM0ω. In this case, the determination is the same as in step (I4) described above, except that the specific numerical values are different. and,
If it is outside the range, the process proceeds to steps (112) and (113) in sequence and processes similar to the above (1110) and (111) are performed.On the other hand, when it is within the range, the process proceeds to step (I9) and the motor, transfer charger (6) ) and the exposure lamp (5) are both turned off.

Next, during main charging (2) and transfer charger (6)
For dirt detection, in the flow of Figure 2 and the road, for example, by adding dirt detection steps between steps (I4) and (I5) and between steps (18) and (9). good. For example, steps (I4) and (1
The determination step to be added during 5) is to determine whether the voltage is within the range of 700 to 100 OV, which indicates a normal case.If it is not within the range, proceed to the step (addition) of displaying dirt; If it is within the range, proceed to step (I5). If it is not within the range of 700V-1000V (7)ffl, first set the voltage to 600V in step (4).
600 things that are determined to be more than 10QOV or less
This means that it is in the contamination range of V to 700 V.

In the above-described embodiment, the reference data may be input to RAM and rewritten. Moreover, the rotating body on which the illuminant is arranged may be a belt instead of a drum.

As described above, according to the present invention, the output of the surface potential sensor is compared with a reference value or a reference range by the control means to detect abnormality or dirt in the charger, so that it is possible to detect abnormalities or dirt in the charger. There is no need to provide a detection circuit dedicated to the high voltage unit or a dedicated alarm line, which makes it possible to reduce the cost of the electrophotographic apparatus, and has the advantage that dirt on the charger can be electrically detected.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the configuration of essential parts of an electronic copying machine embodying the present invention, and FIG. 2 is a flowchart for explaining its operation. (1) - Rotating drum, (2) - Main charger. (3)--Surface potential sensor, (6)...Transfer charger. (9)--CPU (detection means), OI-ROM.

Claims (3)

[Claims] (1) In an electrophotographic apparatus equipped with a charger system that charges the surface of a rotating body on which a photoreceptor is arranged, and a surface potential sensor that detects the surface potential of the rotating body, during warm-up before electrophotographic operation. An electrophotographic apparatus comprising: a control means for detecting an abnormality in the charger system by comparing the output of the surface potential sensor with a predetermined reference value. (2) The electrophotographic apparatus according to claim 1, wherein the control means is a microcomputer. (3) In an electrophotographic apparatus that includes a charger that charges the surface of a rotating body on which a photoreceptor is arranged, and a surface potential sensor that detects a surface potential of the rotating body, the surface of the rotating body may be charged during warm-up before an electrophotographic operation. An electrophotographic apparatus comprising: a control means for detecting dirt on the charger by determining whether the output of the potential sensor is within a predetermined reference range.