KR950004446B1 - Method for preventing reverse charging in an electrophotographic printer - Google Patents

Abstract

To prevent reverse polarity charging of the imaging drum (107), the copy sheet feed (109) is commenced and then energisation of the charging unit (104), position sensor (111) and light source (105). The image transfer unit (106) is energised coincident with the arrival of the copy sheet front edge. When the position sensor (111) is de-activated the exit of the copy sheet rear edge is signalled. A time interval dependent on copy sheet size is determined to allow the sheet to clear the image transfer stage (106). The latter is switched off, the image (103) fixed and the charging unit (104) de-energised.

Description

Anti-reversal Method in Electrophotographic Printers

1 is a conceptual diagram of an electron development method.

2 is a conventional control circuit diagram.

3 is a conventional flow chart.

4 is a flow chart according to the present invention.

The present invention relates to a method for preventing reverse charging in an electrophotographic developing printer.

As shown in FIG. 1 of the general electrophotographic development system, a photosensitive drum 107 for forming an electrostatic latent image, a charging unit 104 for providing a uniform charge to the photosensitive drum 107, and the electrostatic latent image An exposure unit 105 generated on the photosensitive drum 107, a developing unit 108 for developing the impressions exposed on the photosensitive drum 107, and a transfer unit for transferring the developer formed on the photosensitive drum 107 to paper. 106, a register roll unit 109 in charge of conveying paper, a fixing unit 103 for fusing a developer developed on paper, and a jam sensor 101, 111 for detecting a conveyance state of paper. And a mechanism control unit 201 for generating a motor for the operation and a signal for each mechanical control as shown in FIG. 2, and a control signal for controlling the charging, developing, and transferring units 104, 105, and 106. With a developing processor control unit 202. A sensor input unit 203 for inputting detection values of the jam sensors 101 and 111 and various sensors, an image data generation unit 205 for generating data to be written on the content to be printed on paper, and an interface for connecting to the outside A unit 206, a CPU and a control unit 204 for controlling the respective units.

When the operation of the system is operated, the printer waits for a print command in a ready state for a print operation, where the length of the paper to be printed and the conditions of the developing processor are set inside the CPU and the controller 204 when the print command is input.

The condition setting of the developing processors initiates the transfer of paper to align the paper at the register roller 109 and the exposure length on the photosensitive drum 107 at the distance BD of the transfer unit 106 to the register roller 109. (AB) is transferred by the side (BD-AB), and then the exposure is started to match the top margin of the paper. After that, as long as there is no abnormality in conveying the paper, it is exposed by the paper length. When the paper is conveyed by the paper length, the exposure and developing conditions are released, the paper is discharged, and the printing operation is completed to wait for the next print command. If an abnormality occurs in the paper transfer during the printing, it is detected by the jam sensors 101 and 111 and input to the CPU and the control unit 204 through the sensor input unit 203.

The exposure data to be transmitted to the exposure unit 105 is processed when the one-page data is transferred from the computer or the video controller through the interface unit 206 to the CPU and the control unit 204, and is transmitted to the image data generation unit 205. The image data generator 205 provides the exposure unit 105 with the exposure unit 105.

That is, conventionally, when the printer receives a command to print, as shown in the flow chart of FIG. 3, the paper picks up from the cassette, passes through the feed roller, passes through the register roller 109, and reaches the transfer unit 106 at the position of the transfer unit. 106 is turned on, and the toner image formed on the OPC drum 107 is adhered to the paper, and the transfer unit (when the rear end of the paper reaches the transfer unit 106 watch is passed by the length of the paper based on the cassette detected when picking up. 106) was turned off. In other words, the transfer unit 106 was turned off after the time from the on of the transfer unit 106 to the off of the transfer unit 106 passed a certain length of paper, for example, A4 for A4 and B4 for B4.

As described above, since the off time of the transfer unit 106 is determined from the on of the transfer unit 106 on the basis of a certain size of paper, for example, a transfer unit in the case of printing a paper shorter than the length of A4 in the A4 cassette is printed. Off time of the transfer unit 106 at the time of turning on the 106, that is, the transfer time is turned on by the length of A4, so that the transfer is turned on even after the paper has passed, and the toner is adhered to the transfer unit 106 to take the next sheet of paper. Will affect the printed image. In addition, there was a problem that the drum 107 is reversed and affects the apparatus.

Accordingly, an object of the present invention is to provide a method for preventing adverse charges and reducing adverse effects on the device.

Another object of the present invention is to provide a method for preventing unnecessarily adhering toner to a paper by adjusting a transfer unit transfer-off timing when printing a short-length paper into a cassette that can hold paper of a certain size.

Hereinafter, with reference to the accompanying drawings a preferred embodiment of the present invention will be described in detail.

4 is a flow chart according to the present invention, which starts paper feeding, turns on the charging unit and the register sensor, turns on the exposure unit, and checks whether the leading edge of the paper reaches the transfer unit position. A second step of turning on the transfer unit when the leading edge of the paper reaches the transfer unit position, a third step of checking whether the register sensor is turned off after turning on the transfer unit in the second step, and in the third step When the register is turned off, the fourth process of checking the same time as the paper BC passes by the distance BC of the register sensor 111 from the transfer unit 106, and the transfer unit is turned off when the time passes in the fourth process. After the settlement, a fifth process of turning off the charging unit is performed.

In other words, according to the present invention, after the paper to be printed turns on the register sensor 111, the paper is continuously checked whether the rear end of the paper passes through the register sensor 111 and the register sensor 111 is turned off. If the transfer unit 106 is turned off after the time count, the phenomenon in which toner is unnecessarily adhered to the transfer unit 106 by the reverse charging of the transfer unit 106 can be prevented, and the drum 107 is reversely reversed. It is intended to prevent the elements that may affect the burn.

The operation of the embodiment of the present invention will be described in detail with reference to FIGS. 1 to 2 and 4, when the printer driving inputs the start driving signal in the ready state, the CPU and the control unit 204 check the device control unit ( 201) to start paper feeding in step 4a, and control the development processor control unit 202 in step 4b to turn on the charging unit 104, and in step 4c, through the sensor input unit 203. The exposure unit 105 is turned on through the image data generator 205 in step 4d by receiving the ON state of the register sensor 111.

Then, the sheet reaches the transfer unit 106 through the register roller 109 through the register sensor 111 under the control of the mechanism control unit 201, and checks whether the sheet is reached in step 4e. This is checked in accordance with the value counted by the CPU and the controller 204 after passing the register sensor 111.

Then, the developing processor control unit 202 is controlled to turn on the transfer unit 106 in step 4f, and check whether the sensor input unit 203 is turned off in step 4g.

In the process (4g), if the paper is fed so that printing can be sufficiently performed when the register sensor 111 is turned off in the process (4g), it is considered that the transfer is completed when a certain time is reached. The processor controller 202 is controlled to turn off the transfer unit 106, and when the register sensor 111 is not turned off in step (4g), it is determined that the time elapsed by the length A4 from the counted value in step (4h) is determined. Check it. If the register sensor 111 is turned off in the process 4i when the corresponding time elapses, the transfer unit 106 is turned off through the processes 4k and 4l. After the transfer unit 106 is turned off, the fixing unit 103 is settled in the fixing unit 103 by the operation of the mechanical control unit 201 in the process of (4m), and the charging unit is controlled by the control of the developing processor control unit 202 in the process 4n. Off.

As described above, in the laser and LED printer using the electrophotographic processor according to the present invention, when a short-length paper is put into a certain standard and printed, the toner does not unnecessarily come to the transfer unit due to reverse transfer of the transfer unit. Prevents drum reversal and ensures clean and stable burns.

Claims (1)

A method for preventing reverse charge in an electrophotographic developing method, comprising: a first process of starting paper feeding, turning on the charging unit and the register sensor, turning on the exposure unit, and checking whether the paper leading edge reaches the transfer unit position; A second step of turning on the transfer unit when the leading edge of the paper of the first step of the first step reaches the transfer unit position, and a third step of checking whether the register sensor is turned off after turning on the transfer unit in the second step; When the register is turned off in the third process, the fourth process of checking the same time by passing the paper by the distance BC of the register sensor 111 from the transfer unit 106, and when the time passes in the fourth process A method of preventing reverse charging in an electrophotographic printer, characterized in that it comprises a fifth step of turning off and fixing the transfer unit and then turning off the charging unit.