KR100242121B1 - Method for controlling transcribing voltage - Google Patents

Abstract

end. The technical field to which the invention described in the claims belongs

A transfer voltage control method of an image forming apparatus employing an electrophotographic development method.

I. The technical problem that the invention is trying to solve

If the initial printing or the printing is performed for a long time without performing the printing, the transfer voltage is unstable to prevent the upper end of the initial printing from being blurred.

All. Summary of Solution of the Invention

An initial print retrieval step of retrieving whether printing is first performed after power is supplied, a transfer voltage providing step of providing a transfer voltage to a transfer roller for a predetermined time in the case of the initial printing, and When the supply is complete, characterized in that it comprises a printing step for performing the printing.

la. Important uses of the invention

It is used in an image forming apparatus employing an electrophotographic developing method.

Description

Transfer voltage control method. {METHOD FOR CONTROLLING TRANSCRIBING VOLTAGE}

The present invention relates to an image forming apparatus employing an electrophotographic developing method, and more particularly, to a transfer voltage control method.

1 is a schematic diagram of an engine of an image forming apparatus employing an electrophotographic developing method such as a copier, a laser beam printer, an LED print head (LPH) printer, a plain paper facsimile machine, and the like. A conventional electrophotographic development process will be described in detail with reference to FIG. 2.

First, when a print command is provided from the host, the engine controller (not shown) drives the main engine (not shown), and at the same time applies a negative charging voltage to the charging roller 14 and exposes the exposure apparatus. Initial exposure is commanded at (16).

As the main engine is driven, the photosensitive drum 18 and a plurality of rollers rotate. Then, as the negative (-) charging voltage is applied to the charging roller 14, the surface of the charging roller 14 has a negative potential. In this state, the charging roller 14 and the photosensitive drum 18 contact and rotate to charge the surface of the photosensitive drum 18 to a negative potential.

After that, when the charged portion of the photosensitive drum 18 rotates to reach the position of the developing roller 18, the engine controller supplies a positive developing voltage to the developing roller 18. Accordingly, a developer having a negative potential is attached to the surface of the developing roller 18. At this time, the amount of the developer adhering on the developing roller 18 is regulated by the regulating blade 20.

The engine control unit then drives the exposure apparatus 16 and the paper conveying apparatus. The exposure apparatus 16 scans light onto the negatively charged photosensitive drum 18 corresponding to the image to be formed under the control of the engine controller. Here, a portion of the photosensitive drum 18 to which light is scanned, that is, an exposure portion, has a positive potential, and thus an electrostatic latent image composed of a negative potential and a positive potential is formed on the photosensitive drum 18.

At the same time, the engine control unit drives the feed roller 10 and the register roller 12, which are paper feed devices, and transfers the paper toward the transfer roller 24 and the photosensitive drum 18.

Here, as described above, the exposure apparatus 16 forms an electrostatic latent image on the photosensitive drum 18, and then the portion where the electrostatic latent image is formed is attached to the developing roller 22 when it rotates in contact with the developing roller 22. The existing developer is transferred to the exposed portion of the electrostatic latent image. Accordingly, the electrostatic latent image is visualized.

When the sheet is transferred between the transfer roller 24 and the photosensitive drum 18, and the portion of the photosensitive drum 18 on which the visualized image is formed reaches the transfer roller 24, the engine control unit transfers the transfer roller 24 to the transfer roller 24. Apply positive transfer voltage.

The transfer voltage is much higher than the potential of the exposed portion of the photosensitive drum 18 so that the developer attached to the photosensitive drum 18 is transferred onto the paper by the electrostatic force. As described above, the paper conveyed with the developer is passed through the heat roller 28 and the pressure roller 26, which are fixing units, and the developer on the paper is fused to the paper, thereby completing the image formation.

Here, as described above, the transfer roller 24 transfers the developer on the photosensitive drum 18 onto the paper by electrostatic force. That is, the transfer roller 24 should have a potential to attract the developer on the photosensitive drum 18 in order to transfer the developer normally onto the paper as described above.

However, referring to FIG. 3, which shows a waveform diagram of the transfer voltage provided to the transfer roller 24 during initial printing or when printing is not performed for a long time, the potential of the transfer voltage is increased in an unstable section during initial printing. Not constant Accordingly, in the unstable section during the initial printing, the transfer roller 24 does not have a potential to attract the developer on the photosensitive drum 18. That is, the transfer roller 24 cannot normally transfer the developer on the photosensitive drum 18 onto the paper in the unstable section during the initial printing.

In addition, the transfer voltage provided to the transfer roller 24 also has a waveform as shown in FIG. 3 when printing is not performed for 30 minutes or longer.

Accordingly, conventionally, when printing is performed during initial printing or when printing is not performed for a long time, the image at the upper end portion of about 5 to 10 [mm] is blurred.

As described above, in the prior art, when the initial printing or the printing is performed for a long period of time, the printing is not normally performed, and thus, the upper end of the initial printed matter is blurred.

Accordingly, an object of the present invention is to provide a transfer voltage control method for performing stable transfer even when printing is performed during initial printing or not printing for a long time.

1 is a schematic engine mechanism of an image forming apparatus employing a conventional electrophotographic developing method;

FIG. 2 is a typical drive timing diagram of the components of FIG. 1;

3 is a waveform diagram of a transfer voltage during initial printing;

4 is a driving waveform diagram of each component of FIG. 1 according to a preferred embodiment of the present invention;

5 is a block diagram of a conventional laser beam printer;

6 is a flowchart of a printing method of controlling a transfer voltage according to a preferred embodiment of the present invention;

7 is a flowchart illustrating processing of a video controller at power down according to an exemplary embodiment of the present invention.

The present invention for achieving the above object is an initial print search step for searching whether the printing is performed for the first time after the power is applied, and the transfer voltage providing step of providing a transfer voltage to the transfer roller for a predetermined time in the case of the initial printing; And a printing step of performing printing when the provision of the transfer voltage for the predetermined time is completed.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description and the annexed drawings, numerous specific details are set forth in order to provide a more thorough understanding of the present invention. It will be apparent to those skilled in the art that the present invention may be practiced without these specific details. And a detailed description of known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

In the present invention, the transfer voltage is unstable when the transfer voltage is applied at the time of initial printing or when the printing is not performed for a long time. Therefore, the transfer voltage is applied to the transfer roller before printing in the case of initial printing or when printing after printing for a long time. When performing the transfer substantially, the transfer voltage in a stable state is applied to the transfer roller.

4 is an engine driving timing diagram of an image forming apparatus employing an electrophotographic developing method according to a preferred embodiment of the present invention. Hereinafter, referring to FIGS. 1 and 4, the characteristics of the transfer voltage are compensated according to an embodiment of the present invention. The electrophotographic development process will be described.

First, when a print command is provided from a host or a video control unit or the like, the engine control unit (not shown) provides a transfer voltage to the transfer roller 24 for a predetermined time. At this time, the transfer voltage corresponds to an unstable section, after which the transfer voltage is not unstable. Since the engine drive timing is the same as the conventional.

FIG. 5 is a block diagram of a conventional laser beam printer, which is an image forming apparatus employing an electrophotographic development method to which the present invention can be applied. The laser beam printer includes a video controller 30 and a print engine. The part 40 and the operation panel 38 are comprised. The video controller 30 includes a computer interface 32, a video control unit 34, and an engine interface 36. The computer interface 32 is connected between the host computer and the video control unit 34 to interface the transmission and reception signals between the host computer and the video control unit 34. The video controller 34 includes a ROM having a control program and a RAM temporarily storing various data. Also, the video controller 34 converts the print data received from the host computer through the computer interface 32 into image data that the print engine 40 can process and transmits the image data to the print engine 40. The engine interface 36 interfaces the input / output signals between the video control unit 34 and the print engine unit 40.

The operation panel 38 is controlled by the video controller 34 and includes a plurality of keys for inputting various commands and a display device for displaying information according to the operation of the laser beam printer.

The print engine unit 40 includes a video interface 42, an engine control unit 44, an input / output (I / O) interface 46, a sensor circuit 48, an instrument driving unit 50, and an electrophotographic developing unit 52. ) And is connected to the video controller 30. The video interface 42 provides an interface for input and output signals between the video controller 30 and the engine controller 44. The engine controller 44 controls the mechanical drive unit 50 and the electrophotographic developing unit 52 according to the control of the video controller 30, and forms an image according to the image data received from the video controller 30 on the paper. In addition, the engine controller 44 detects an operation state of each part of the print engine unit 50 through the sensor circuit 48. The I / O interface 46 is connected between the engine controller 44, the sensor circuit 48, the mechanical driver 50, and the electrophotographic developing unit 52 to interface the input / output signals of the engine controller 44. The sensor circuit 48 drives various sensors for detecting the operation state of each part of the print engine unit 40, the paper feeding and conveying state, the developer amount, and the like, and the detection signal of each sensor is transmitted to the engine control unit 44. to provide. The mechanism driving unit 50 drives various mechanisms for feeding and conveying paper and forming images under the control of the engine control unit 44. The electrophotographic developing unit 52 controls image data under the control of the engine control unit 44. The image is formed on paper by the electrophotographic developing method.

6 shows a flowchart of a printing method for controlling a transfer voltage according to a preferred embodiment of the present invention. When power is applied, the video controller 34 of the laser beam printer performs step 54. In step 54, the video controller 34 reads the power-off time. When the read of the power off time ends, the video controller 34 searches for the time when the power was cut off by subtracting the power off time from the current time. When the power down time is found, the video controller 34 stores the power down time. When the storing of the power down time ends, the video controller 34 performs step 56. In step 56, the video controller 34 initializes the non-print time timer.

Here, the non-printing time timer is a timer for measuring the time of not printing.

When the initialization of the non-print time timer is finished, the video controller 34 drives the non-print time timer from the instant of initialization of the non-print time timer, so that the non-print time timer generates information on the non-print time. When the initialization of the non-print time timer is finished, the video controller 34 performs step 58. In step 58, the video controller 34 searches whether a print command is provided from the host. If the print command is provided from the host, the video control unit 34 performs step 60, otherwise performs step 74. In step 74, the video controller 34 performs a corresponding operation. In step 60, the video controller 34 reads the power cutoff time. If the read of the power-off time is finished, the video controller 34 performs step 62. In step 62, the video controller 34 reads the non-print time of the non-print time timer. When the reading of the non-printing time is completed, the video controller 34 performs step 64. In step (64), the video controller 34 performs step (66) when the power cutoff time is longer than a predetermined time or the non-printing time is longer than a predetermined time, and the power cutoff time is cleared or the power cutoff time and the nonprinting time. If it is shorter than this predetermined time, step (74) is performed. The constant time may be 30 minutes, which is a time for which the transfer characteristic is lowered.

In operation 66, the video controller 34 provides a command to the engine controller 44 to compensate for the transfer voltage characteristic. At this time, the video controller 34 applies a transfer voltage to the transfer roller according to the command. When the application of the transfer voltage is terminated, the engine controller 44 performs step 68. In step 68, the engine controller 44 searches whether a predetermined time has elapsed. At this time, the engine control unit 44 performs step (70) if a predetermined time has elapsed, and otherwise performs step (66). In step 70, the engine controller 44 cuts off the transfer voltage provided to the transfer roller. When the transfer voltage is cut off, the engine controller 44 performs step 72. In step 72, the video controller 34 clears the power down time. When the clear is completed, the video controller performs step 74. In step 74, the video controller 34 converts the print data provided from the host into image data and provides the image data to the engine controller 44. The engine controller 44 forms an image according to the image data on the paper.

As described above, the present invention determines whether to complement the characteristics of the transfer voltage based on the power off time. Accordingly, in the preferred embodiment of the present invention, when the power supply of the laser beam printer is cut off, the power-off time is stored and when the power is connected, the time for which the power is turned off is retrieved.

7 is a flowchart illustrating the processing of the video controller 34 when the power is turned off. When power is cut off from the laser beam printer, the video controller 34 stores the power off time. When the storing of the power off time ends, the video controller 34 performs step 74. In step 74, the video controller 34 performs a normal power off operation.

As described above, in the present invention, the transfer voltage applied to the transfer roller is unstable during initial printing or when printing is performed for a long time, but the transfer voltage is applied to the transfer roller in advance in such a case. Do not print when unstable. As a result, as printing is performed in a period where the transfer voltage is unstable, it is possible to prevent the image from being output poorly.

As described above, the present invention has the advantage that the image quality is prevented from being output during initial printing or when printing is not performed for a long time.

Claims (3)

In the transfer voltage control method of an image forming apparatus employing an electrophotographic development method, Storing the power-off time when the power is cut off to the image forming apparatus; Calculating and storing a power cutoff time by subtracting the power cutoff time from a current time when power is reconnected to the image forming apparatus; Searching if the power down time is longer than a first predetermined time when a print command is provided from a host; Providing a transfer voltage to the transfer roller for a second predetermined time when the power cutoff time is longer than the first predetermined time; And when the provision of the transfer voltage for the second predetermined time is completed, performing printing according to the print command. According to claim 1, wherein the transfer voltage control method, And clearing the power off time after the printing. The method of claim 2, wherein the transfer voltage control method comprises: Initializing a non-printing time timer after calculating the power off time and driving the non-printing time timer; Searching if the non-printing time is longer than the first schedule time if the power-off time is shorter than the first schedule time or the power-off time is cleared after a print command is provided from the host; Providing a transfer voltage to the transfer roller for a second predetermined time if the non-printing time is longer than the first predetermined time; And when the provision of the transfer voltage for the second predetermined time is completed, performing printing according to the print command.

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