KR100485845B1 - Image printing apparatus and method of controling thereof - Google Patents

Abstract

An image printing apparatus and a control method thereof are disclosed. The image printing apparatus includes a photosensitive medium, a light scanning device for scanning light onto the photosensitive medium, a developing device for developing an electrostatic latent image formed by the light scanning device on the photosensitive medium with a developer, and an image developed with the developer to the photosensitive medium. A transfer roller to be transferred to the paper to be printed, a print engine state diagnosis unit for detecting an effective resistance value between the photosensitive medium and the transfer roller, and a transfer to be applied to the transfer roller during printing according to the effective resistance value in the print engine driving condition determination mode. And a control unit for determining a voltage and determining a print mode driving voltage for the light source of the optical scanning device using the determined transfer voltage, and a light source driving unit controlled by the control unit to drive the light source. In addition, the control method of the image printing apparatus includes determining the transfer voltage to be applied to the transfer roller in response to the combined resistance of the transfer roller and the photosensitive medium, and according to the information of the print engine driving condition determining factor including the determined transfer voltage. And determining the driving voltage (optical power) for the print mode of the light source of the yarn device. According to such an image printing apparatus and its control method, it is possible to adjust the driving conditions of the print engine in accordance with the change of the environment of the system and to suppress the deterioration in print quality.

Description

Image printing apparatus and method of control

 BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image printing apparatus and a method of controlling the same, and more particularly, to an image printing apparatus and a method of controlling the same, wherein the driving voltage of the light source is determined according to a system condition.

An image printing apparatus prints an image on recording paper, and includes a copying machine and a printer.

Such an image printing apparatus includes an inkjet method and a laser printing method according to a printing method of a printing engine. Recently, an image printing apparatus using a laser printing method having a high printing speed has been widely used.

The printing engine to which the laser printing method is applied is developed on a photosensitive medium by a photoreceptor, a photosensitive medium for forming an electrostatic latent image corresponding to light emitted from the optical scanning device, and a developing device and a developer for developing an electrostatic latent image formed on the photosensitive medium. And a transfer apparatus for transferring the captured image onto a recording medium.

Among the elements of the printing engine, the driving voltage of the light source is fixed so that the driving voltage is fixed or the part of the light emitted from the light source is monitored to compensate for aging due to use. The method of adjusting the power was applied.

However, since the printing quality is determined not only by the variation in the amount of light emitted from the light source, but also by the characteristic change of the photosensitive medium, the printing method of correcting the driving voltage of the light source so as to maintain the constant amount of light emitted from the light source as in conventional printing There is a problem that the print quality deterioration due to aging of the engine cannot be sufficiently compensated.

The present invention is to solve the above problems, the present invention was devised to improve the above problems, according to the characteristics of the printing engine to properly adjust the driving conditions of each element of the printing engine to improve the print quality It is an object of the present invention to provide a sustained image printing apparatus and a control method thereof.

In order to achieve the above object, an image printing apparatus according to the present invention includes a photosensitive medium, a photonic scanning device for scanning light onto the photosensitive medium, and a latent electrostatic image formed by the optical scanning device on the photosensitive medium with a developer. An image printing apparatus having a developing device and a transfer roller for transferring an image developed with the developer onto a photosensitive medium, the printing roller comprising: a printing engine state diagnosis unit detecting an effective resistance value of the photosensitive medium and the transfer roller; And determine a transfer voltage to be applied to the transfer roller when printing in the print engine driving condition determination mode according to the effective resistance value, and determine the drive voltage for the print mode for the light source of the optical scanning device using the determined transfer voltage. And a light source driver controlled by the controller to drive the light source according to the driving voltage for the print mode. do.

The control unit may further include a transfer voltage adjusting unit that is controlled by the control unit and variably adjusts a voltage applied to the transfer roller, wherein the control unit detects the effective resistance value by the print engine state diagnosis unit in the print engine driving condition determination mode. It is preferable to control the transfer voltage adjusting unit so that a test voltage increasing in a predetermined pattern is applied to the transfer roller.

The print engine state diagnosis unit compares a current detection unit for detecting a current flowing from the transfer roller to the photosensitive medium in response to the test voltage, and a current signal detected by the current detection unit with a set target value, and when the target value is reached. And a comparator for outputting a target value reaching signal to the controller, wherein the controller is configured to determine a voltage applied to the transfer roller as the transfer voltage of the transfer roller to be used in the printing mode when the target value reaching signal is input. It is desirable to.

The current detector detects a current from effective resistance values of the transfer roller and the photosensitive medium which are changed by external temperature, stake, toner, and the like.

More preferably, further comprising a photo detector for monitoring and outputting a portion of the light emitted from the light source, the control unit determines the driving voltage of the light source for the print mode by using a signal fed back from the photo detector do.

The control unit determines the driving voltage for the print mode of the light source by using the transfer voltage of the transfer roller and the output signal of the photodetector.

In addition, the control method of the image printing apparatus according to the present invention to achieve the above object comprises the step of determining the transfer voltage to be applied to the transfer roller corresponding to the combined resistance of the transfer roller and the photosensitive medium and the determined transfer voltage And determining the driving voltage for the print mode of the light source of the optical scanning device, that is, the optical power, according to the information of the printing engine driving condition determining factor.

The step of determining the driving voltage of the light source is preferably determined using the amount of light emitted from the light source with respect to the voltage applied to the light source as the printing engine driving condition determining factor.

More preferably, the step of determining the driving voltage for the print mode of the light source comprises the steps of determining a first driving voltage of the light source corresponding to the determined transfer voltage and driving the light source with the first driving voltage of the light source; Detecting the amount of light emitted from the light source and if the amount of light emitted from the light source is in error with a target amount of light corresponding to the first driving voltage, correcting the value of the first driving voltage to compensate for the error, thereby printing the light source; Determining the driving voltage for the mode.

Hereinafter, an image printing apparatus and a control method thereof according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram showing an image printing system to which an image printing apparatus according to the present invention is applied.

Referring to the drawings, an image printing system includes a computer 10 and an image printing apparatus 30 connected through a communication interface 20.

The computer 10 is an external device for transmitting print data to the image printing apparatus 30.

As another example of an external device that may be connected to the image printing apparatus 30, a scanner (not shown) may be applied.

The printer driver 11 installed in the storage device (not shown) of the computer 10 provides a menu for setting printing conditions, converts the selected print target file into print data for the image printing apparatus, and prints the image through the communication interface 20. Transmit to device 30.

Preferably, the printer driver 11 includes a menu for selecting an effective resistance value between the photosensitive drum 41 and the transfer roller 45 for determining the driving conditions of the print engine 40 of the image printing apparatus 30. In addition, a menu for selecting and inputting a change in image sharpness, that is, a dark / blur brightness is provided. In this case, the printer driver 11 transmits the effective resistance value setting information selected for the provided menu to the image printing apparatus 30 as the effective resistance setting information value.

The image printing apparatus 30 processes so that an image corresponding to the received print data is recorded on the recording sheet.

The image printing apparatus 30 includes an interface unit 31, an input unit 33, a display unit 35, a control unit 37, a print engine unit 40, and a print engine state diagnosis unit 50.

The interface unit 31 supports signal communication between the computer 10, which is an external device, and the control unit 37, through the communication interface 20.

The input unit 31 is provided with a plurality of keys for setting various functions supported by the image printing apparatus 30. Preferably, the input unit 31 is provided with a key for setting the change of the image sharpness corresponding to the effective resistance value, that is, the brightness of the dark / blur.

The display unit 35 is controlled by the control unit 37 to display the display information.

The print engine 40 is controlled by the controller 37 to perform printing. The print engine 40 includes a paper feeder, a light scanning device, a photosensitive medium, and a transfer roller.

Some elements of the print engine 40 are shown in FIG. 2.

Referring to the drawings, the printing engine 40 includes a photosensitive drum 41, a charger 42, a light scanning device 43, a developing device 44 and a transfer roller 45.

The charger 42 charges the photosensitive drum 41 applied to the photosensitive medium to a predetermined potential.

The optical scanning device 43 is controlled by the control unit 37 to scan light to the photosensitive drum 41 in correspondence with the print data.

The photodetector (PD) 48 is provided to detect some of the light emitted from the light source provided in the optical scanning device 43 and feed back to the control unit 37.

The developing device 44 develops the electrostatic latent image formed on the photosensitive drum 41 by the optical scanning device 43 with a developer having a charge.

The transfer roller 45 is rotated in engagement with the photosensitive drum 41 to print the image developed on the photosensitive drum 41 on the recording paper 49 to be inserted.

In the figure, Rtr represents the effective resistance of the transfer roller 45, and Ropc represents the effective resistance of the photosensitive drum 41.

The voltage variable part 46 is provided so that voltage may be applied to the transfer roller 45.

The transfer voltage adjusting unit 47 controls the voltage varying unit 46 so that a voltage corresponding to the control signal input from the control unit 37 is applied to the transfer roller 45.

The print engine state diagnosis unit 50 is constructed to detect an effective resistance value between the photosensitive drum 41 and the transfer roller 45.

Preferably, the print engine state diagnosis unit 50 is configured to detect a current flowing through the conduction path from the transfer roller 45 to the photosensitive drum 41 and output a signal corresponding thereto.

An example of the print engine state diagnosis unit 50 is illustrated in FIG. 3.

Referring to the drawings, the print engine state diagnosis unit 50 includes a current detector 51, a current-voltage converter 53, and a comparison unit 55.

The current detector 51 is provided on the energization loop from the transfer roller 45 to the photosensitive drum 41.

The current-voltage converter 53 outputs a voltage signal corresponding to the current detected by the current detector 51.

The comparator 55 compares the reference voltage corresponding to the set target current with the signal output from the current-voltage converter 53 and outputs an effective resistance value corresponding to the comparison result to the controller 37.

Reference numeral 43a is a light source driver that is controlled by the control unit 37 to adjust the driving voltage of the light source 43b of the optical scanning device 43, and control on / off switching of the light source 43b in correspondence with the print data.

The control unit 37 controls each unit, determines driving conditions for each element of the printing engine unit 40 according to the effective resistance value of the printing engine unit 40, and a printing operation may be performed according to the determined driving conditions. The print engine 40 is controlled so that it is controlled. Herein, an initialization process for determining the driving conditions of the print engine 40 is called a print engine driving condition determination mode, and a mode for performing a print job according to the determined driving conditions of the print engine 40 is called a printing mode. The print engine driving condition determination mode may be set to be performed every time the power switch of the image printing apparatus 30 is turned on or whenever print data is received from an external device.

In the printing engine driving condition determination mode, the factors to determine the printing engine driving conditions include the transfer voltage of the transfer roller 45 and the drive voltage of the light source 43b.

The control unit 37 uses the effective resistance between the transfer roller 45 and the photosensitive drum 41, the light output characteristic change information of the light source 43b, and the like as the determinants for determining such driving conditions.

Here, the effective resistance value is changed by external temperature, stake, toner, and the like. Alternatively, the printer driver 11 or the input unit 33 may be configured to allow the user to select and set the change of the image sharpness corresponding to the effective resistance value, that is, the brightness / darkness.

In the look-up table (LUT) 37a in the control unit 37, driving voltage information to be applied to the light source 43b in correspondence with the transfer voltage is recorded.

Hereinafter, a process of acquiring such driving condition determinant information and determining the driving condition of the print engine unit 40 by using the acquired determinant information will be described with reference to FIG. 5.

5 is a flowchart showing a preferred control method of the image printing apparatus according to the present invention. As shown in the figure, the control section 37 determines the transfer voltage corresponding to the effective resistance of the transfer roller 45 and the photosensitive drum 41 (step 110).

Referring to the process of determining the transfer voltage in more detail, the control unit 37 controls the transfer voltage adjusting unit 47 so that a test voltage increasing in a predetermined pattern is applied to the transfer roller 45.

The test voltage pattern is preferably applied to increase stepwise as shown in FIG.

Subsequently, the control unit 37 applies a voltage that is incrementally increased to the transfer roller 45 according to the test voltage pattern, and when a signal corresponding to the set reference current is input from the comparator 55, the transfer roller 45 at this time. Determine the voltage applied to) as the transfer voltage. That is, as shown in FIG. 4, in the process of increasing the voltage applied to the transfer roller 45 step by step, the comparison unit 55 detects that a current corresponding to the reference current set at the time T6 was detected by the current detector 51. ), The control unit 37 determines the voltage Vt applied to the transfer roller 45 at the time T6 as the transfer voltage to be applied to the transfer roller 45 in the print mode.

When the transfer voltage to be applied to the transfer roller 45 is determined such that the current corresponding to the reference current set in the conduction path from the transfer roller 45 to the photosensitive drum 41 flows, the sensitization of the photosensitive drum 41 may occur. The electrostatic latent image formation and the transfer conditions of the electrostatic latent image developed with the charged developer to the paper can be kept constant.

When the transfer voltage to be applied to the transfer roller is determined during printing, the first driving voltage of the light source 43b is primarily determined using the transfer voltage of the transfer roller (step 120). Here, the first driving voltage of the light source corresponding to the determined transfer voltage is stored in the lookup table 37a of the controller 37.

The control unit 37 firstly determines the driving voltage of the light source 43b by reading the first driving voltage of the light source corresponding to the determined transfer voltage information from the lookup table (LUT) 37a.

The control unit 37 detects the amount of light output from the photodetector 48 (step 140) while driving the light source with the first driving voltage of the first determined light source (step 130).

Subsequently, the controller 37 determines whether there is an error between the target amount of light corresponding to the first driving voltage of the light source 43b and the amount of light detected by the photodetector 48, and if there is an error, the error is corrected. The driving voltage of the light source 43b is finely corrected to determine the driving voltage of the light source 43b to be applied in the printing mode (step 150). For example, when the amount of light output from the photodetector 48 is smaller than the target light amount corresponding to the first driving voltage, a voltage obtained by adding a predetermined voltage to the first driving voltage is determined as the driving voltage of the light source 43b. In the driving voltage correction of the light source 43b in step 150, the error correction may be repeatedly performed by an error correction method using a normal negative feedback feedback until the error decreases below a set value.

As a method of determining a transfer voltage according to another aspect of the present invention, a constant voltage is applied to the transfer roller 45, and between the photosensitive drum 41 and the transfer roller 45 from a current value output from the current detector 51. The effective resistance value may be calculated, and the transfer voltage value of the transfer roller 45 corresponding to the calculated effective resistance value may be determined. In this case, the lookup table 37a only needs to record the transfer voltage data to be applied corresponding to the effective resistance value between the photosensitive drum and the transfer roller. In this case, the comparison unit 55 may be omitted.

While the invention has been described in detail only with respect to the described embodiments, it will be apparent to those skilled in the art that various modifications and variations are possible within the spirit of the invention, and such modifications and variations belong to the appended claims.

As described so far, according to the image printing apparatus and the control method thereof according to the present invention, it is possible to adjust the driving conditions of the print engine in accordance with the change of the environment of the system, thereby suppressing the deterioration in print quality.

1 is a block diagram showing an image printing system to which an image printing apparatus according to the present invention is applied;

2 shows some elements of FIG. 1, FIG.

3 is a block diagram illustrating an example of a print engine state diagnosis unit for detecting an effective resistance between the photosensitive medium and the transfer roller of FIG. 2;

4 is a graph showing an example of a test voltage pattern applied to a transfer roller in a print engine driving condition determination mode;

And,

5 is a flowchart showing a preferred control method of the image printing apparatus according to the present invention.

* Description of symbols on the main parts of the drawings *

30: image printing apparatus 40: printing engine unit

50: print engine status diagnosis unit

Claims (8)

Supplying a photosensitive medium, a light scanning device for scanning light onto the photosensitive medium, a developing device for developing an electrostatic latent image formed by the light scanning device on the photosensitive medium with a developer, and supplying an image developed with the developer to the photosensitive medium. An image printing apparatus comprising a transfer roller for transferring to a sheet of paper, A print engine state diagnosis unit detecting an effective resistance value of the photosensitive medium and the transfer roller; In the printing engine driving condition determination mode, the transfer voltage to be applied to the transfer roller during printing is determined according to the effective resistance value, and the driving voltage for the print mode for the light source of the optical scanning device is determined using the determined transfer voltage. A controller; And a light source driver controlled by the controller to drive the light source according to the driving voltage for the print mode. The apparatus of claim 1, further comprising a transfer voltage adjusting unit which is controlled by the control unit and variably adjusts a voltage applied to the transfer roller. The control unit controls the transfer voltage adjusting unit to apply a test voltage, which is increased in a predetermined pattern, to the transfer roller so that the print engine state diagnosis unit detects the effective resistance value in the print engine driving condition determination mode. An image printing apparatus. The method of claim 2, The print engine state diagnosis unit may include a current detector configured to detect a current flowing from the transfer roller to the photosensitive medium in response to the test voltage; And a comparing unit comparing the current signal detected by the current detecting unit with a set target value and outputting a target value reaching signal to the controller when the target value is reached. And the control unit determines the voltage applied to the transfer roller as the transfer voltage of the transfer roller to be used in the print mode when the target value reaching signal is input. The apparatus of claim 3, further comprising a photodetector configured to monitor and output a part of the light emitted from the light source. And the control unit determines a driving voltage of the light source for the print mode by using a signal output from the photodetector. The image printing apparatus according to claim 3, wherein the control unit determines the driving voltage for the print mode of the light source by using the transfer voltage of the transfer roller and the output signal of the photodetector. Supplying a photosensitive medium, a light scanning device for scanning light onto the photosensitive medium, a developing device for developing an electrostatic latent image formed by the light scanning device on the photosensitive medium with a developer, and supplying an image developed with the developer to the photosensitive medium. In the control method of the image printing apparatus comprising a transfer roller for transferring to a sheet of paper, Determining a transfer voltage to be applied to the transfer roller in response to the combined resistance of the transfer roller and the photosensitive medium; And determining a driving voltage for the print mode of the light source according to the amount of light emitted from the light source with respect to the voltage applied to the light source, including the determined transfer voltage. delete The method of claim 7, wherein the determining of the driving voltage for the print mode of the light source Determining a first driving voltage of the light source corresponding to the determined transfer voltage and the external temperature information; Driving the light source to the first driving voltage of the light source; Detecting an amount of light emitted from the light source; If the amount of light emitted from the light source is in error with a target amount of light corresponding to the first driving voltage, correcting the first driving voltage value so as to compensate for the error and determining the driving voltage for the print mode of the light source; A control method of an image printing apparatus, characterized in that.