JPH0616201B2 - Electrophotographic device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus used for a high speed printer or the like.

2. Description of the Related Art FIG. 4 is a schematic configuration diagram showing an example of a conventional electrophotographic apparatus.

This electrophotographic apparatus has a drum-shaped photosensitive member 1.
A photoconductive layer is formed on the surface of the photoreceptor 1. A charger 2, an exposure device 8, a conductive sleeve 11 and the like are arranged around the photoconductor 1 along the clockwise rotation direction.

The surface of the photoconductor 1 is uniformly charged in advance to a predetermined potential by the charger 2. Then, when light corresponding to the image information is applied thereto by the exposure device 8, the charged charges on the photoconductor 1 are selectively erased, and the electrostatic latent image of the image to be reproduced is latent image portion 9a. Is formed. The non-latent image portion 9b is kept in a charged state in a portion which is not irradiated by the exposure device 8. On the other hand, the conductive sleeve 11 is applied with a voltage of about 1000 V, which is substantially the same as the charging potential of the photosensitive recording medium charged by the charger 2, and also conveys the developer 10 containing colored fine particles called toner to the photoreceptor 1. I am trying to do it. Then, the latent image portion 9a of the photoreceptor 1 becomes the conductive sleeve 1
When reaching 1, the developer 10 adheres to the latent image portion 9a due to the mutual potential difference, and the visible image portion 12 is formed.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the electrophotographic apparatus as described above, the developer may adhere to the non-latent image portion when the recording process starts and stops. This wastes the developer. Further, the adhered developer may scatter during transfer to stain the device or its surroundings, or to make an image on a transferred recording paper unclear.

Adhesion of the developer causing the above-mentioned problems occurs due to the following reasons.

That is, as shown in FIGS. 5 and 6, the rising and falling slopes of the potential in the charging portion of the photosensitive recording medium, which are determined by the switching time of the charger and the potential strength of the charger, and the rising and falling of the potential of the conductive sleeve. A difference occurs in the gradient, and this difference causes a potential difference between the non-latent image portion of the photosensitive recording medium and the conductive sleeve, and this potential difference causes the developer to adhere.

The present invention has been made in view of the above problems, and the developer does not adhere to the non-latent image portion at the time of starting and stopping the operation of the recording process, wasteful consumption of the developer, and developer at the time of transfer. It is an object of the present invention to provide an electrophotographic apparatus capable of suppressing the scattering of particles and the blurring of an image on a recording paper to be transferred.

Means for Solving the Problems In order to achieve the above object, the present invention provides a charging means of an electrophotographic apparatus in which a rising and falling gradient of the potential of a conductive sleeve is stored in advance and a photosensitive storage medium. Means for controlling the current to the charger for supplying the electric charge based on the stored contents stored in the storage means.

In addition to the contents described above, the storage means stores the moving speed of the photosensitive storage medium (the rotation speed if the photosensitive storage medium is a drum).
In consideration of the above, the time until the photosensitive storage medium charging section charged by the charging unit reaches the conductive sleeve may be stored as the stored content. By taking this time into consideration, it is possible to correct the relative time lag between the driving of the charging unit and the developing unit, and to make the charged potential of the photosensitive member and the applied potential of the conductive sleeve at the time of development highly accurate. .

When the working device is started, a photosensitive storage medium (hereinafter abbreviated as a photoconductor) is rotated first. Along with this, the control means controls the current to the charger based on the stored content stored in the storage means. Then, the charger applies the potential of the gradient set in consideration of the stored contents, that is, the rising gradient of the potential of the conductive sleeve and the rotation speed, to the photoconductor.
Then, an electrostatic latent image is formed on the charged photoconductor by the charging means based on the image information. On the other hand, a voltage is applied to the conductive sleeve after a predetermined time has passed after the start operation of the device. This rising application gradient is substantially the same as the rising gradient of the photoconductor, and there is almost no potential difference between the non-latent image part of the photoconductor and the conductive sleeve, and the developer adheres to the non-latent image part. Can be suppressed.

When the apparatus is stopped, the charger applies the falling potential to the photoconductor in consideration of the falling gradient and the rotation speed of the potential of the conductive sleeve. As the photoconductor charging section applied with a falling slope reaches the conductive sleeve, the voltage application to the conductive sleeve is stopped. At this time, the potential falling gradient of the conductive sleeve is substantially the same as the potential falling gradient of the photoconductor, and the adhesion of the developer to the non-latent image portion of the photoconductor is suppressed.

Embodiment 1 FIG. 1 is a schematic configuration diagram showing an electrophotographic apparatus according to an embodiment of the present invention, and the same members as those in FIG. 4 are designated by the same reference numerals.

This electrophotographic apparatus is arranged in the vicinity of the photoconductor 1 and includes a charging unit 50 for charging the photoconductor 1, a hopper 20 containing the developer 10, a conductive sleeve (hereinafter abbreviated as sleeve) 11, and the like. It comprises means 51 and a power supply circuit 52 connected to the sleeve 11.

The charging unit 50 is a charger 2 that supplies an electric charge to the photoconductor 1.
And the potential rising slope of the sleeve 11 (see FIG. 2), the falling slope (see FIG. 3), and the charger 2 to the sleeve 1
The storage unit 3 in which information such as the rotation time of the photoconductor 1 until reaching 1 is stored in advance, and the power supply 4 and the storage unit 3 are connected to control the voltage of the power supply 4 based on the stored information It has a unit 5, a control unit 5 and a charger 2, which is connected to the charger 2 and boosts a voltage controlled by the controller 5 and supplies the boosted voltage to the charger 2.

The power supply circuit 52 includes the power supply 13, the resistor 14 connected in parallel to the power supply 13, and the opening / closing means 21 connected between these and the sleeve 11. The resistor 14 shortens the rise time of the potential of the sleeve 11 and stabilizes it.

The operation of the electrophotographic apparatus configured as described above will be described below.

The apparatus is started and the photoconductor 1 is rotated first. Along with this, the potential rising slope of the sleeve 11 stored in the storage unit 3 and the rotation time of the photoconductor 1 from the charger 2 to the sleeve 11 are input to the control unit 5.
Then, the control unit 5 controls the voltage of the power supply 4 based on the input information. The controlled voltage value is boosted by the booster 6 and applied to the charger 2. Then, the photoconductor 1 is charged by the charger 2 with a potential rising gradient. After that, the photoconductor 1 is continuously charged to substantially the same potential.

Then, when the photoconductor 1 rotates and a predetermined portion thereof reaches the exposure device 8, the exposure device 8 irradiates the photoconductor 1 based on the image information. Then, an electrostatic latent image is formed on the latent image portion 9a of the photoconductor 1. Further, the portion not irradiated by the exposure device 8 is in a charged state as the non-latent image portion 9b.

On the other hand, after a lapse of a predetermined time after the start operation of the apparatus, the opening / closing means 21 is turned on and a voltage having substantially the same potential as the charger 2 is applied to the sleeve 11. At this time, the voltage is gradually applied to the sleeve 11 with a predetermined gradient (potential rising gradient). As shown in FIG. 2, the potential rising gradient is substantially equal to the potential rising gradient of the photoconductor 1, and there is almost no potential difference between the non-latent image portion 9b and the sleeve 11, and the non-latent image portion is not generated. 9
The adhesion of the developer 10 to b is suppressed.

When the apparatus is stopped, the charger 2 charges the photoconductor 1 with a falling slope based on the stored information including the falling slope of the sleeve 11. When the non-latent image portion 9b of the photoconductor 1 charged with the falling slope reaches the sleeve 11, the opening / closing means 21 is turned off and the voltage is applied to the sleeve 11. Be stopped. At this time, the potential falling gradient of the sleeve 11 is substantially equal to the potential falling gradient of the photoconductor 1 as shown in FIG. 3, and the developer 10 adheres to the non-latent image portion of the photoconductor 1. It can be suppressed.

In the case of the present embodiment, the time required for the photoreceptor 1 charged by the charger 2 to reach the sleeve 11 is stored in the storage unit 3 in advance, and this is input to the control unit 5, so that it is more accurate. High control is possible.

According to the present invention, the potential rising slope and the falling slope of the conductive sleeve are stored in the storage unit, the voltage supplied to the charger is controlled based on the stored information, and the controlled voltage value is controlled. Since the photoconductor is charged by, it is possible to prevent the developer from adhering to the non-latent image portion at the time of starting and stopping the operation of the storage process, which leads to wasteful consumption of the developer, scattering of the developer at the time of transfer, There is an effect that it is possible to suppress blurring of the image of the transferred storage paper.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an electrophotographic apparatus according to an embodiment of the present invention, FIG. 2 is a potential rising characteristic diagram relating to the apparatus, and FIG.
FIG. 4 is a potential fall characteristic diagram of the apparatus, FIG. 4 is a schematic configuration diagram of a conventional electrophotographic apparatus, FIG. 5 is a potential rise characteristic diagram of the apparatus, and FIG. 6 is a potential fall characteristic of the apparatus. It is a characteristic diagram. 1 ... photosensitive member, 2 ... charging device, 3 ... storage unit, 4 ... power source, 5 ... control unit, 7 ... charging unit, 8 ... exposure unit, 9a
... latent image part, 9b ... non-latent image part, 11 ... conductive sleeve, 21 ... opening / closing means, 50 ... charging means, 51 ... developing means.

Claims (1)

[Claims] 1. A rotating photoconductor, charging means for charging the photoconductor, exposing means for exposing the charged photoconductor to an image information portion, and downstream of the exposing means in the rotational direction of the photoconductor. And a developing means for developing with a conductive sleeve to which a predetermined potential is applied, the charging means providing time response characteristic information of the applied potential of the conductive sleeve and charging and developing timing information. It is characterized by comprising a storage means for storing and a control means for controlling the charging current so that the charging potential of the photoconductor at the time of development and the applied potential of the conductive sleeve are made equal based on the stored information. Electrophotographic device.