KR101193455B1 - Method for preventing bad image from being printed and electro-photographic image forming appatus thereof - Google Patents

Abstract

The present invention relates to a method for preventing defective image printing and an electrophotographic image forming apparatus to which the same is applied, the image forming apparatus comprising: a high voltage power supply unit for applying a predetermined voltage to a charging roller, a developing roller, and a transfer roller; A high pressure detector detecting a voltage of at least one of the charging roller, the developing roller, and the transfer roller; And a controller for stopping a print job when it is determined that there is a roller to which high pressure is not applied, based on the detected voltage information of each roller.

According to the present invention, in an electrophotographic image forming apparatus such as a laser printer which performs printing by charging, exposing, developing, transferring and fixing, the voltage applied to the charging roller, the developing roller, or the transfer roller is normal. When the voltage is smaller than the voltage required for printing, printing can be stopped to prevent a bad image from being output.

Description

Method for preventing bad image from being printed and electro-photographic image forming appatus}

1 is a schematic cross-sectional view of a conventional electrophotographic image forming apparatus.

2 is a flowchart showing a printing routine of a general electrophotographic image forming apparatus.

3 is a block diagram showing the configuration of an electrophotographic image forming apparatus according to an embodiment of the present invention.

4 is a conceptual diagram illustrating a configuration of the voltage comparison mixing unit of FIG. 3.

5A and 5B are flowcharts illustrating an operation of a method for preventing a bad image print according to an exemplary embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus. In particular, a defective image printing which prevents problems such as set contamination, waste of toner, fuser jams, etc., which occur when a voltage applied to a charging roller, a developing roller, or a transfer roller is inappropriate. A prevention method and an electrophotographic image forming apparatus using the same.

In general, electrophotographic image forming apparatuses, such as a laser printer, an LED print head (LPH) printer, and a facsimile, perform printing operations through charging, exposing, developing, transferring, and fixing processes.

1 is a schematic cross-sectional view of a conventional electrophotographic image forming apparatus.

Referring to FIG. 1, an electrophotographic image forming apparatus includes a photosensitive drum 100, a charging roller 110, a laser scanning unit (LSU) 120, a developing roller 130, a transfer roller 140, A high voltage power supply unit (HVPS) 150, a controller 160, and a roller current detector 170 are provided. Hereinafter, a printing operation of the electrophotographic image forming apparatus will be described with reference to FIG. 1.

First, the high voltage power supply unit 150 generates the high pressure required by the charging roller 110, the developing roller 130, and the transfer roller 140 under the control of the controller 160, and generates the high pressure for each roller. To apply.

The charging roller 110 uniformly charges the surface of the photosensitive drum 100 by the charging voltage applied from the high voltage power supply unit 150.

The optical scanning device 120 scans the light corresponding to the image data input from the controller 160 to the uniformly charged photosensitive drum 100. Accordingly, an electrostatic latent image is formed on the surface of the photosensitive drum 100.

The developing roller 130 receives a developing voltage from the high voltage power supply unit 150 and supplies toner to the surface of the photosensitive drum 100. Accordingly, a toner image is formed on the latent electrostatic image formed on the surface of the photosensitive drum 100.

The transfer roller 140 is driven by the transfer voltage applied from the high voltage power supply unit 150 to transfer the toner image formed on the photosensitive drum 100 onto the recording paper. Then, the toner image transferred to the recording paper is fixed to the printing paper by the high heat and pressure of the fixing unit (not shown) and discharged to the outside, thereby completing printing.

On the other hand, the roller current detection unit 170 detects the current flowing in the charging roller 100, the developing roller 130, the transfer roller 140 and transmits to the control unit 160.

The controller 160 receiving the sensed current determines a printing environment such as temperature and humidity in an environmental recognition step, and resets a voltage applied to each roller according to the determined printing environment.

In the electrophotographic image forming apparatus as described above, even if the output of the high-voltage power supply unit 150, i.e., the charging voltage, the developing voltage, and the transfer voltage is smaller than the voltage required for normal printing, the printing paper is processed after all the processes. To discharge. In this case, if the charging voltage is small, problems such as set contamination, toner waste, and fuser jam may occur due to black paper output, and if the developing voltage is small, the white paper is output and the color is lost and the image is poor. Is output. In addition, if the transfer voltage is small, the image is blurred, resulting in toner waste and set contamination.

The technical problem to be solved by the present invention is to stop printing when the voltage applied to the charging roller, the developing roller, or the transfer roller is smaller than the voltage required for normal printing in an electrophotographic image forming apparatus such as a laser printer. The present invention provides an electrophotographic image forming apparatus capable of preventing bad image output, waste toner, and the like, and a method of preventing bad image printing of the apparatus.

An electrophotographic image forming apparatus to which a defective image printing prevention method according to the present invention for achieving the above technical problem is provided comprises: a high voltage power supply unit for applying a predetermined voltage to a charging roller, a developing roller, and a transfer roller; A high pressure detector detecting a voltage of at least one of the charging roller, the developing roller, and the transfer roller; And a controller for stopping a print job when it is determined that there is a roller to which high pressure is not applied, based on the detected voltage information of each roller.

According to an aspect of the present invention, there is provided a method for preventing a bad image printing, comprising: detecting a voltage of at least one of a charging roller, a developing roller, and a transfer roller; Determining whether high pressure is applied to each roller based on the detected voltage of each roller; And stopping the printing operation when it is determined that there is a roller to which high pressure is not applied.

Hereinafter, a method and an apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

2 is a flowchart showing a printing routine of a general electrophotographic image forming apparatus.

When the user turns on the image forming apparatus, the image forming apparatus warms up a boot sequence, raises the temperature of the fixing unit, and checks whether various units such as a developer are operating properly (step 200).

Next, the printing environment such as temperature and humidity is recognized (step 210). This is because, even when the charging voltage and the transfer voltage are constantly applied, the resistance value of each roller is changed according to the printing environment, so that the actual voltage of the roller may be different from the applied voltage value. The electrophotographic image forming apparatus detects a current flowing through the charging roller 110 or the transfer roller 140 by the roller current sensing unit 170, and uses the applied voltage and the sensed current to resist the roller. Detect the value. The controller 160 detects a printing environment based on the detected resistance value, and sets a charging voltage, a developing voltage, and a transfer voltage suitable for the detected printing environment.

When the environmental recognition is finished, the process proceeds to the print standby state and waits for a print command (step 220).

In operation 230, it is determined whether a print command has been received. If there is no print command in step 230, it is in the print standby state (step 220). If there is a print command in step 230, the print environment is recognized again as in step 210 (step 240).

After the recognition of the environment, the high voltage power supply unit 150 applies a high voltage charging voltage to the charging roller 110 (step 250). The surface of the photosensitive drum 100 is uniformly charged by the charging roller 110 applied the voltage.

Light corresponding to the image data is scanned on the surface of the charged photosensitive drum 100 by the optical scanning device 120 to form an electrostatic latent image (step 260).

The high voltage power supply unit 150 applies a high voltage developing voltage to the developing roller 130 (step 270). Toner is supplied to the surface of the photosensitive drum 100 having the electrostatic latent image formed by the developing roller 130 applied with the voltage to form a toner image.

The high voltage power supply unit 150 applies a high voltage transfer voltage to the transfer roller 140 (step 280). The toner image formed on the photosensitive drum 100 is transferred to the recording paper by the transfer roller 140 to which the voltage is applied. Then, the toner image transferred to the recording paper is fixed to the printing paper by the high heat and pressure of the fixing unit (not shown) and discharged to the outside, thereby completing printing.

Figure 3 is a block diagram showing the configuration of an electrophotographic image forming apparatus according to an embodiment of the present invention, the photosensitive drum 300, the charging roller 310, the optical scanning device 320, the developing roller 330, It comprises a transfer roller 340, a high voltage power supply unit 350, a control unit 360, a high pressure detector 370 and a voltage comparison mixing unit 380.

Operation of the photosensitive drum 300, the charging roller 310, the optical scanning device 320, the developing roller 330, the transfer roller 340, the high-voltage power supply unit 350 of the above-described components of FIG. Since the operation is the same, a detailed operation description will be omitted.

The high pressure detector 370 detects a voltage applied to the charging roller 310, the developing roller 330, and the transfer roller 340. The voltage detection method of the high pressure detector 370 may include detecting a current flowing through each of the rollers and then detecting the applied voltage based on the detected current value and the resistance of the roller. . Information about the detected roller voltages is transmitted to the controller 360. The method of transferring the detected roller voltages without the voltage comparison mixing unit 380 and the voltage comparison mixing unit 380 are provided as the transfer method. There is a method of transferring each detected roller voltage to one output. In particular, the latter method uses a comparator (not shown) that compares the detected voltages of the rollers with a constant voltage, and outputs each comparator output to a logic gate (such as an end gate or an OR gate). By using a bundle to output to the control unit 360. Although a circuit for binding to one output is added, the controller 360 checks only one signal without checking the voltage applied to each roller, thereby reducing the load on the processor of the controller 360. There is this.

The control unit 360 determines that there is a roller to which high pressure is not applied based on voltage information of each roller provided from the high pressure detecting unit 370, in addition to serving as a control part for each component of the image forming apparatus described above. Stops the print job.

4 is a conceptual diagram illustrating a configuration of the voltage comparison mixing unit of FIG. 3.

The charging voltage 400, the developing voltage 405, and the transfer voltage 410 detected by the high voltage detecting unit 370 are reference voltages 415 corresponding to the voltages of the rollers through the comparators 430, 435, and 440. , 420, 425. The comparators 430, 435, and 440 output a logic value '1' when the corresponding roller voltage is smaller than the reference voltage. The comparator outputs are mixed through the or gate 445 and provided as one output. When any of the comparators 430, 435, and 440 has an output value of '1', the or gate 445 is also set to a logic value of '1'. Output ' Therefore, when high pressure is not applied to any one of the rollers, the voltage comparison mixing unit 380 outputs '1', and the process of the control unit 360 that receives the mixed output value has a small load. There is an advantage.

5A and 5B are flowcharts illustrating an operation of a method for preventing a bad image printing according to an exemplary embodiment of the present invention, each of which corresponds to steps 210 and 240 and f1, which are environmental recognition steps of FIG. 2.

5A is a flowchart illustrating an operation of an environment recognition step according to an embodiment of the present invention.

The high voltage power applying unit 350 applies high pressure to the charging roller 310 or the transfer roller 340 to recognize the environment (step 500).

The high pressure detector 370 detects the voltages of the charging roller 310 and the transfer roller 340, and then transfers information about the detected voltages to the controller 360, and the controller 360 is the charging roller. In operation 310, it is determined whether high pressure is applied to the transfer roller 340.

If it is determined in step 505 that there is a roller to which high pressure is not applied, the control unit 360 stops the print job (step 515). If it is determined that the high pressure is normally applied in step 505, after setting the environmental recognition value such as temperature, humidity (step 510). Proceeds to print standby mode.

5B is a flowchart illustrating an operation of a print job step according to an embodiment of the present invention, and corresponds to f1 of FIG. 2.

The charging roller 310 uniformly charges the surface of the photosensitive drum 300 by the charging voltage applied from the high voltage power supply unit 350 (step 520).

The high pressure detecting unit 370 detects the voltage of the charging roller 310 and provides the voltage to the controller 360, and the controller 360 determines whether the high pressure is applied to the charging roller 310 based on the provided information. (Step 525).

If it is determined in step 525 that the high pressure is not applied, the controller 360 stops the print job (step 535). If it is determined in step 525 that high pressure is applied, an exposure step is performed (step 530). That is, the optical scanning device 320 scans the light corresponding to the image data input from the controller 360 to the photosensitive drum 300. Therefore, the electrostatic latent image is formed on the surface of the photosensitive drum 300.

The developing roller 330 receives a developing voltage from the high voltage power supply unit 350 and supplies toner to the surface of the photosensitive drum 300 (step 540). Therefore, a toner image is formed on the electrostatic latent image formed on the surface of the photosensitive drum 300.

The high pressure detector 370 detects a voltage of the developing roller 330 and provides the voltage to the controller 360, and the controller 360 determines whether high pressure is applied to the developing roller 330 based on the provided information. (Step 545).

If it is determined in step 545 that the high pressure is not applied, the control unit 360 stops the print job (step 535). If it is determined in step 545 that the high pressure is applied, the transfer step is performed (step 550). That is, the transfer roller 330 driven by the transfer voltage applied from the high voltage power supply unit 350 transfers the toner image formed on the photosensitive drum 300 to the recording paper.

The high pressure detector 370 detects a voltage of the transfer roller 340 and provides the voltage to the controller 360, and the controller 360 determines whether high pressure is applied to the transfer roller 340 based on the provided information. (Step 555).

If it is determined in step 555 that the high pressure is not applied, the controller 360 stops the print job (step 535). If it is determined in step 555 that high pressure is applied, printing is completed by discharging the recording paper after the fixing step (step 560).

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. I will understand that. Accordingly, the true scope of the present invention should be determined by the appended claims.

According to the present invention, in an electrophotographic image forming apparatus such as a laser printer which performs printing by charging, exposing, developing, transferring and fixing, the voltage applied to the charging roller, the developing roller, or the transfer roller is normal. When the voltage is smaller than the voltage required for printing, printing can be stopped to prevent a bad image from being output.

As a result, it is possible to prevent problems such as set contamination, toner waste, and fuser jams due to black paper output generated when charging high pressure is not applied, and to prevent white paper output or missing color caused by developing high pressure. Can be. In addition, it is possible to prevent problems such as blur of the output image caused by not applying the transfer high pressure.

Claims (5)

A high voltage power supply unit for applying a predetermined voltage to the charging roller, the developing roller, and the transfer roller; A high pressure detector for detecting the voltage of at least one of the rollers during the printing operation by applying the voltage to the charging roller, the developing roller, and the transfer roller; And And a control unit for stopping the predetermined print job if it is determined that there is a roller applied with a voltage less than the voltage required for normal printing based on the detected voltage of each roller. Photographic image forming apparatus. The method of claim 1, The high pressure detector detects a current flowing through each of the rollers, and then detects the voltage of each of the rollers based on the sensed current value and the resistance of each of the given rollers. Photographic image forming apparatus. The method according to claim 1 or 2, Compare the detected voltage of each roller with a reference voltage corresponding to the voltage of each roller, and group the values representing the result of comparison between the voltage of each roller and the corresponding reference voltage as a logic gate as one output. An electrophotographic image forming apparatus to which a bad image printing prevention method further comprising a voltage comparison mixing unit which is transmitted to the control unit. Applying a predetermined voltage to at least one of a charging roller, a developing roller, and a transfer roller; Detecting a voltage of at least one of the rollers while the voltage is applied to the charging roller, the developing roller, and the transfer roller to perform a printing operation; Determining whether a voltage lower than a voltage necessary for normal printing is applied to each roller based on the detected voltages of the rollers; And And stopping the predetermined print job when it is determined that there is a roller applied with a voltage less than the voltage required for the normal printing. 5. The method of claim 4, The detecting may include detecting a current flowing through each of the rollers, and then detecting a voltage of each of the rollers based on the detected current value and the resistance of each of the rollers.

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