JPH0212289A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To detect abnormality with a destaticizing lamp without providing a dedicated part on the title device by using a surface potential sensor for controlling the electrostatic charge of a photosensitive body. CONSTITUTION:The surface potential of a drum 10 is detected by the surface potential sensor 12 during a copying operation, and the data thereof are sent to a CPU 19 wherefrom a control signal is sent to a high-voltage unit 17 so that the potential of a drum surface by electrostatic charge applied by a main charger thereto is maintained constant. Dirt of the destaticizing lamp is detected before the copying operation by this surface potential sensor 12 to control the electrostatic charge through the use of the output thereof prior to the copying operation (that is, during warming up). A detecting operation is performed by the CPU 19. By using the output of the surface potential sensor 12 in this way, the dirt of the destaticizing lamp can be detected electrically without requiring a special part or performing electrooptical conversion.

Description

DETAILED DESCRIPTION OF THE INVENTION 1. Presentation The present invention relates to an electrophotographic apparatus such as an electronic copying machine, and more particularly to detection of dirt on a static elimination lamp thereof.

Conventionally, in an electronic copying machine, for example, a charging unit consisting of a charger scans an original along the rotation direction of a photoreceptor drum rotating at a constant speed, and the surface of the photoreceptor drum is exposed to light reflected. exposure area.

Developing section. A transfer section and a static elimination section are provided. Then, a latent image is formed in the exposing section on the photosensitive surface of the photosensitive drum charged in the charging section, and further developed in the developing section to obtain a developed image, and the developed image is transferred to the transfer section from the paper feeding section. Transfer to the fed paper. The latent image remaining on the surface of the photoreceptor drum in the transfer section is removed by irradiating it with light in the static eliminating section. The photoreceptor drum that has been affected by the static eliminator waits for the next charging.

By the way, if the static elimination lamp becomes dirty and the static elimination is no longer effective, electric charges remain on the surface of the photoreceptor drum, causing uneven density and making it impossible to obtain a normal electrophotographic image. I end up. Therefore, a means to detect dirt on the static elimination lamp is required, but in conventional electrophotographic equipment, as shown in Figure 4, the amount of light emitted by the static elimination lamp (1) that is connected to the power supply of AClooV and turned on by the flow of current is required. The level was detected by a photosensor (2) and was given as data to the CP TJ (3) to judge whether the static elimination lamp was dirty. Note that (4) is a triarch that performs switching control of the alternating current flowing through the static elimination lamp using a signal from the CPU (3).

As mentioned above, in the conventional example, a special detection component such as a photo sensor must be installed to detect dirt on the static elimination lamp, which makes the configuration complicated and , which had the disadvantage of high cost.

The present invention has been made in view of the above points, and an object of the present invention is to provide an electrophotographic apparatus that can detect dirt on a static elimination lamp without providing a dedicated detection component.

In order to achieve the above object, the present invention includes a charger for charging the surface of a photoconductor, a surface potential sensor for controlling the charging of the photoconductor, and a charger for controlling the charging of the photoconductor. In an electrophotographic apparatus equipped with a static elimination lamp that removes static electricity, the surface potential sensor detects the potential on the surface of the photoreceptor charged by the charger, and after the static elimination lamp is activated in a state where the light of the static elimination lamp is made weaker than usual. The electrostatic discharge lamp is configured to include a control means for detecting dirt on the static elimination lamp by detecting the potential on the surface of the photoreceptor with the surface potential sensor and comparing the difference between the two potentials with a predetermined reference value.

According to this configuration, dirt on the static elimination lamp is detected using the output of the surface potential sensor for charge control included in the electrophotographic device, and the static elimination is performed using a control means such as a microcomputer. No special parts are required, and electricity and electricity can be detected.
It is detected electrically without any optical conversion or the like.

Back” L5 Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of the main parts of an electronic copying machine embodying the present invention, and (10) is a photosensitive drum having a photosensitive member disposed on its surface, which rotates in the direction of the arrow. Around this rotating drum (10), along the rotation direction, there are a main charger (11), a surface potential sensor (12), a selfoc lens (13), an ill light lamp (14),
A transfer charger (15) and a static elimination lamp (16) are provided in this order. Of course, other components such as a developing device and a separate charger are arranged around the rotating drum (10), but these components are omitted for simplicity of illustration.

(17) is a high voltage unit, CPU (19)
to 110 baud) Based on a control signal given through (18), a high voltage is supplied to charging devices such as the main charger (11) and transfer charger (15). (
21) is a static elimination lamp lighting circuit that similarly lights the static elimination lamp (16) based on a control signal given from the CPU (19) via the I10 port (18). (22) detects the zero cross point of the AC power supply voltage for the static elimination lamp [Fig. 2 (a)], and the detection signal [second
Figure (b)] is passed through the 1,10 boat (18) to the CPU.
(19) is a zero-cross detection circuit that supplies the circuit. CPU
(19) is normally controlled to drive the static elimination lamp (16) with a full wave of the AC power voltage, but when detecting dirt, the static elimination lamp (16) is controlled to drive with a half wave of the AC power voltage. Figure (c)].

FIG. 2(d) shows the control signal waveform output from the CPU (19) at that time and applied to the static elimination lamp lighting circuit (21). The original purpose of the surface potential sensor (12) is to detect the surface potential of the drum (10) during copying, send the data to the CPU (19), and send the data from the CPU (19) to the high voltage unit. l-(17
) to keep the potential on the drum surface constant due to the charging applied from the main charger or the like. However, in this embodiment, dirt on the static elimination lamp is detected before the copying operation by using the output before the copying operation (that is, during warm-up) among the outputs of the surface potential sensor (12) for charging control. It has become. The detection operation is performed by the CPU (19), and the operation will be explained with reference to the flowchart in FIG.

First, in step (I1), the motor is turned on to rotate the rotary drum (10), and the transfer charger (15)
and the exposure lamp (14) are turned on. After that, in step (112), the CPU (19) waits for y seconds to pass, and in the next step (I3), the CPU (19) detects the surface potential sensor (
12) Read the output value. The above-mentioned 7 seconds is selected as a sufficient time for the surface of the drum (10) charged by the transfer charger (15) to face the surface potential sensor (12), and the starting point is at step (I1). This is the start point of the ON operation. Note that both of these 7 seconds and 2 seconds, which will be described later, are executed by a timer counter in the microcomputer including the CPU (19).

The CPU (19) stores the value read in the step (I3) in the ROM (20) in the next step (114).
) compared with the data set in advance. This data indicates that the transfer charger (15) is abnormal (therefore, the transfer charger (15) is disconnected, or the high voltage unit (17)
This is the boundary value for determining whether or not a failure occurs. Here, if it is determined that there is some kind of defect in the transfer charger (15) or the high voltage unit (17), the process proceeds to step (110) and all of the motor, transfer charger (15) and exposure lamp (14) are turned off. OFF, then step (11)
Process the error in step 1) and return. Here, the abnormality processing may include displaying an abnormality using a lamp or sound. If there is no abnormality as determined in step (I4), the process proceeds to step (I5).

In step (i15), the light intensity of the static elimination lamp (16) is halved and turned on. As mentioned above, this is the zero-order step (
In I6), wait for 2 seconds after the static elimination lamp (16) is turned on, and 2 seconds is selected as a sufficient time for the part that has been neutralized by the static elimination lamp to face the surface potential sensor (12). After waiting 2 seconds in step (I6), the CPU
(19) is the surface potential sensor (12) in step (I7)
Then, the difference between this output value and the value read in step (I3) above is calculated, and this difference is compared with reference data previously stored in the ROM (20). Here, if the difference is not within the standard data range, that is, the difference voltage is small, it means that the potential drop after static elimination is small, and this is because the static elimination effect is insufficient due to dirt on the static elimination lamp. Since this is the case, proceed to step (112) and remove the motor, transfer charger (15), light amount 77" (14), and remove static electricity.
7'(16) Turn OFF In addition, in the next step (1113), abnormality processing (contamination processing) of the static elimination lamp (16) is performed. On the other hand, if the data is within the reference data range, the process advances to step (19) and the motor.

The transfer charger (15), the exposure lamp (14), and the static elimination lamp (16) are each turned off and the process returns.

Detection of dirt on the static elimination lamp is performed in the manner described above.

In the above embodiment, the photoreceptor is configured as a rotating drum, but the photoreceptor may be in the form of a belt. Also, the present invention is applicable not only to electronic copying machines but also to printers and the like. Needless to say.

As mentioned above, the present invention utilizes a surface potential sensor that controls the charging of the photoreceptor, so it has the effect of being able to detect abnormalities in the static elimination lamp without the need for special parts. be.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the main structure of an electronic copying machine embodying the present invention, FIG. 2 is an explanatory waveform diagram thereof, and FIG. 3 is a flowchart of its operation. FIG. 4 is a configuration diagram of a conventional example. (10) --- Rotating drum on which a photoreceptor is arranged. (11)・-Main charger. (12)--Surface potential sensor, (14)--Exposure lamp. (15) --- Transfer charger, (16) --- Static elimination lamp. (17)--High voltage unit, (19)--
CPU. (21)... Static elimination lamp lighting circuit. (22)・-Zero cross detection circuit. Patent issuer I-san Mita Kogyo Co., Ltd. Fig. OM Fig. Fig. Fig.

Claims (2)

[Claims] (1) In an electrophotographic apparatus including a charger that charges the surface of a photoreceptor, a surface potential sensor for controlling the charge of the photoreceptor, and a static elimination lamp that removes the charge from the photoreceptor, the charger charges the surface of the photoreceptor. The potential on the surface of the photoconductor is detected by the surface potential sensor, and the potential on the surface of the photoconductor is detected by the surface potential sensor after the discharge lamp is activated with the light of the discharge lamp made weaker than usual. An electrophotographic apparatus comprising a control means for detecting dirt on the static elimination lamp by comparing the difference with a predetermined reference value. (2) The electrophotographic apparatus according to claim 1, wherein the control means is a microcomputer.