JPS59171971A - Electrifier - Google Patents

Abstract

PURPOSE:To minimize the variance of the potential of electrostatic charge due to the variance of circumstances by providing a control process following an electrostatic charge process. CONSTITUTION:In a corona electrifier 1, an insulated charge wire is stretched in a slender case whose section is U-shaped, and a voltage is applied between the case and the charge wire in air. A roller 3 which has a conductive surface and is brought into contact with a moving surface of a member 2, whose surface electric charge is given when the member 2 is moved in the direction of an arrow while facing the aperture of the corona electrifier 1, and is turned is provided, and a bias voltage is given to the surface of this roller 3 from a power source 4. In this device, rather more electric charge is given to the moving surface of the member 2 by the corona electrifier 1, and thereafter, the roller 3 having the conductive surface to which the bias voltage is impressed is brought into contact with the electrostatic charge surface to absorb and liberate more excess electric charge than the nominal potential.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a charging device for a photoreceptor used in a PPC copying machine, and more particularly to the charging device having means for preventing charging unevenness caused by environmental fluctuations.

PRIOR ART FIG. 1 is a schematic side sectional view of a charger conventionally used in this type of copying machine, in which an insulated charge wire is stretched inside a U-shaped case, and the wire is connected between the two in the atmosphere. (In most cases, the corona charger 1, which applied double pressure, applied an electric charge to the entire surface of the member (photoreceptor) 2 that moved facing the opening of the charger.

According to this method, uneven exposure of the member 2 is likely to occur due to variations in the volume and weight of the member 2, changes in surface speed, deterioration of the banding device 1, and the like.

By first exposing the moving surface of the member 2 to a corona discharge at a potential of about (7) higher than the nominal potential (2 exposures, then a lower potential than the nominal potential), Changes in system parameters of 1 m (=Charging means that are difficult to respond to)
However, according to this charging method, the amount of ozone generated by corona discharge that interferes with the copying function is doubled compared to the rice polishing method. Also, Corona+i￥den 11;
! Due to the gauging of the charging device, more than half of the current from the power supply escapes, and the loss of 7C also occurs in the 9Y device i.
! It has the disadvantage that it doubles to 'f lnil.

Purpose The present invention has been developed in order to improve the disadvantages/disadvantages of the above-mentioned conventional devices, and to reduce uneven charging. In addition, a new control process has been added to make the charging potential uniform without increasing the amount of ozone generated. The objective is to provide a device that can minimize (: stop) the number of disturbances.

Structure The basic requirement of the present invention is that a charging process (two unified control processes) is provided in the means for charging the moving surface of a member to a uniform nominal potential (=electrification), and an embodiment thereof is now shown in the drawings (2). Therefore, the explanation is as follows.

Embodiment 1゜Figure 2 shows an embodiment of the present invention, in which an insulated char and shear wire are stretched inside an m-long case with a cross-sectional shape, and a voltage is applied between them in the atmosphere. When the corona charger 2 moves in the direction of the arrow C2 with its open opening (two faces facing each other), the corona charger 2 is configured to
4 is a roller having a conductive surface that rolls and is placed in contact with the moving surface of the member tnJ, and 4 is a power source that applies a bias voltage to the surface of the roller. In the above-mentioned apparatus, a corona charger 1 (2) applies a slightly larger charge to the moving surface of the member 2, and then a roller 3 (or brush) having a conductive surface to which a bias voltage is applied is brought into contact with the charging surface (2). By doing so, the extra charge greater than the nominal potential is absorbed and released.In the illustrated example, the power supply 4
The surface of the roller 3 (or plan) may be made variable so that the potential can be adjusted, or the surface of the roller 3 (or plan) may be divided to provide different controls depending on the position of the movement surface of the member. (You can do this twice.)

Embodiment FIG. 3 shows another embodiment of the present invention, in which a corona charger 1 applies a charge to the surfaces of members 2 that face each other and move. The amount of charge on the member 2 is detected by the detection device 5,
The signal is input to the control device 4' to change the current applied to the charging roller 3' or the charging brush to control the amount of charge from the 1J-ra or brush, thereby controlling the member 2 (
This prevents uneven charging between the two.

The charging roller 3' may be a roller or a brush waiting for a conductive surface as shown in Example 1 (2), in which case (2) the controller 4' is adapted to control the bias voltage applied to said part. There must be.

That is, the bias voltage in Example 1 was controlled by a signal from the charge amount detection device 5 inserted between the charging process and the control process.

Embodiment 3 FIG. 4 shows another embodiment of the apparatus of the present invention, in which 1 is a corona charger, 2 is a member having a moving surface, 3' is a charging roller or brush (not shown), 4' indicates a control device. In the figure, when a member 2 is charged by a corona charger 1, the current flowing to the corona charger +0) casing increases or decreases as the current flowing to the member 2 increases or decreases at 7. Therefore, this casing current is taken out and the control device 4
' to control charge supply to the charging roller 3' or the charging brush.

In this case, as in the first embodiment, the charging roller can be replaced with a roller having a conductive surface, and the bias voltage thereof can be controlled.

Embodiment 4 FIG. 5 shows another embodiment of the present invention, in which a charging roller 3' charges a member 2 having a front surface that moves along with the charging roller 3', and then detects the charging roller 3'. The amount of charge on the member is detected by the charger 5, and the signal is sent to the control device 4' to control the current supplied to the charge wire of the corona charger 1, which has openings facing each other on the surface. By doing so, the occurrence of unevenness on the surface of the member 2 is prevented.

Of course, the charging roller 3' in L may be a charging flannel.

Effects: According to the present invention, it is possible to reduce variations in charging potential on the surface of a member caused by OPC film thickness variations, photoreceptor fatigue, and the like. That is, it is possible to equalize the charging potential without increasing the amount of ozone generated, which adversely affects the copying function.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram of a charger conventionally used in electrophotographic copying machines, the one shown is a sectional view of a corona charger, and FIGS. FIG. 2 is a schematic diagram of an example. 1... Charger 2 - Member (photoreceptor) 3... Roller with a conductive surface 3'... Charging roller 4... Power supply 4' - Control device 5
...Electric charge detector agent Patent attorney Makoto Kon Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure I

Claims (5)

[Claims] (1) A charging device characterized in that a means for charging a moving surface of a member to a uniform nominal potential includes a control step in the charging step. (2) In the above control process, a solid roller or planar roller to which a bias voltage is applied is provided, and by bringing this into contact with the moving surface, the excess charge placed on the moving surface of the member during the charging process is absorbed ( 41JJ'' feature, as claimed in claim 1; (3) After the charging process for the moving surface of the member, a detection means for detecting the electrification level is provided, and based on the signal corresponding to the value of the band '1u obtained by the detection means (2), ←
←Cattle IJ, characterized in that it includes a control step consisting of contacting said moving surface with a skeleton roller or a blank equipped with a power supply device for varying the applied current. The charging device according to item 1, wherein the range is 1°1. (4) The fourth charging detection means uses the Caning current of the corona charger, detects the potential during the charging process, and uses a conductor roller or brush equipped with a power supply device that changes the applied current based on the signal. The charging device according to claim 1, further comprising a control step of bringing the moving surface into contact. (5) The charging device according to claim 1, wherein a charging roller or a brush is used in the charging step, and a corona charger is provided in the control step.