KR100547818B1 - Apparatus and method for compensation non-linear output characteristic of engine in image forming system - Google Patents

Abstract

end. TECHNICAL FIELD This invention relates to a printer.

I. SUMMARY OF THE INVENTION An object of the present invention is to provide an apparatus and method for compensating for nonlinear output characteristics of an image forming system engine that generates a laser beam to form an image on a paper.

)의 인접 화소 정보들과 튜닝계수들을 입력하여 인접화소들간의 간섭정도를 나타내는 간섭치(

)를 계산하고, 계산된 상기 간섭치(

)와 임계치(T)와의 비교결과에 따라 레이저 다이오드의 출력 주기를 가감하여 상기 이미지데이터에 따른 화상이 인쇄되도록 하는 레이저 출력 조절부로 구성함을 특징으로 한다.All. SUMMARY OF THE INVENTION A nonlinear output characteristic compensator of an image forming system engine using a laser, which stores tuning coefficients in an arbitrary direction for each pixel of image data to be formed and controls the printing operation of the printer. A controller for storing the pixel information of each image data, and a pixel to be compensated from each of the memory and the controller (

The interference value representing the degree of interference between adjacent pixels by inputting adjacent pixel information and tuning coefficients of

), And the calculated interference value (

) And a laser output control unit for printing an image according to the image data by subtracting or outputting the output period of the laser diode according to the comparison result between the threshold value T and the threshold value T.

la. Important uses of the invention: It can be used in color and monochrome laser beam printers.

Printer, engine power, compensation

Description

Nonlinear output characteristic compensator and method of image forming system engine {APPARATUS AND METHOD FOR COMPENSATION NON-LINEAR OUTPUT CHARACTERISTIC OF ENGINE IN IMAGE FORMING SYSTEM}             

1 is an output waveform diagram of a laser diode for explaining the nonlinear output characteristics of a general laser beam printer engine, and an exemplary energy distribution diagram thereof.

2 is a view illustrating a scanning direction of a general laser beam printer.

3 is a block diagram of a nonlinear output characteristic compensation device of an image forming system engine according to an embodiment of the present invention;

4 is an operation flowchart of a nonlinear output characteristic compensating apparatus of an image forming system engine according to an exemplary embodiment of the present invention.

5 is an exemplary energy distribution and output image obtained as a result of driving a nonlinear output characteristic compensation device of an image forming system engine according to an exemplary embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming system using a laser, and more particularly, to an apparatus and method for obtaining an optimal image by compensating for nonlinear output characteristics of an image forming system engine using a laser.

The laser beam printer is an image forming system for printing an image according to print data input from a host through an electrophotographic process on a sheet of paper. The laser beam printer has an engine mechanism structure that converts input print data into image data that can be processed inside the printer and generates a laser beam according to the converted image data to expose the photosensitive member to form an electrostatic latent image on the photosensitive member. . The laser beam is generated by light emission of a laser diode (LD). Therefore, the engine output of the laser beam printer may be referred to as the output of the laser diode (LD). The engine output of the laser beam printer (shown in the form of an output image) corresponds to the pulse value input to emit the laser diode. It will have nonlinearity. Therefore, in general laser beam printers, there is a limit in improving image quality due to nonlinearity of the printer engine output.

파형과 그에 따른 에너지 분포 파형이 도시되어 있다. 도 1에 도시한 바와 같이 소정의 화상을 얻기 위한 레이저 다이오드(LD)의 출력

이 도 1에 도시한 바와 같다면 그에 따른 에너지 분 포는 그 아래에 도시한 것과 같이 나타나므로, 출력 화상은 인접 화소의 간섭이 없는 지점(좌측부분)에서는 소망하는 화상농도 보다 낮은 화상농도를 가지게 되며, 인접 화소의 에너지 간섭이 많은 지점(중앙부분과 우측부분)에서는 소망하는 화상농도 보다 높은 화상농도가 얻어지므로, A에 도시된 바와 같이 레이저 다이오드(LD) 출력

에 대하여 선형성을 가지는 출력화상을 얻기 위해서는 프린터 엔진의 비선형적인 출력 특성을 보상하여 최적의 화상을 얻을 필요가 있다.Referring to this in more detail with reference to FIG. 1, first, FIG. 1 illustrates an output waveform diagram of the laser diode LD and an example of energy distribution according to the nonlinear output characteristic of a general laser beam printer engine. 1 shows an output of a laser diode LD according to predetermined image data.

The waveform and the resulting energy distribution waveform are shown. As shown in FIG. 1, the output of the laser diode LD for obtaining a predetermined image

As shown in Fig. 1, the resulting energy distribution appears as shown below, so that the output image has a lower image density than the desired image density at the point where the adjacent pixels do not interfere (left side). Since the image density higher than the desired image density is obtained at the point (central part and the right part) where the energy interference of adjacent pixels is large, the laser diode LD output as shown in A

In order to obtain an output image having linearity with respect to the nonlinear output characteristic of the printer engine, it is necessary to obtain an optimal image.

Accordingly, an object of the present invention is to provide an apparatus and method capable of compensating for nonlinear output characteristics of an image forming system engine that generates a laser beam to form an image on a paper.

It is still another object of the present invention to provide an apparatus and method for compensating nonlinear output characteristics of an image forming system engine, which can obtain an optimal image by preventing distortion of an image due to energy interference between adjacent pixels.

It is still another object of the present invention to provide an apparatus and method for compensating nonlinear output characteristics of a laser beam printer engine capable of obtaining an optimal image by varying an output of a laser diode by detecting an interference value indicating an interference degree with adjacent pixels in a laser beam printer. In providing.

In order to achieve the above object, the present invention provides a non-linear output characteristic compensation device of an image forming system engine using a laser,                         

A controller which stores tuning coefficients in an arbitrary direction for each pixel of image data to be formed and controls a printing operation of the printer;

A memory for storing each pixel information of the image data;

)의 인접 화소 정보들과 튜닝계수들을 입력하여 인접화소들간의 간섭정도를 나타내는 간섭치(

)를 계산하고, 계산된 상기 간섭치(

)와 임계치(T)와의 비교결과에 따라 레이저 다이오드의 출력 주기를 가감하여 상기 이미지데이터에 따른 화상이 인쇄되도록 하는 레이저 출력 조절부로 구성함을 특징으로 한다.Pixels to compensate from each of the memory and the controller (

The interference value representing the degree of interference between adjacent pixels by inputting adjacent pixel information and tuning coefficients of

), And the calculated interference value (

) And a laser output control unit for printing an image according to the image data by subtracting or outputting the output period of the laser diode according to the comparison result between the threshold value T and the threshold value T.

The present invention also provides a nonlinear output characteristic compensation method of an image forming system engine using a laser.

A data input process of inputting and storing tuning coefficients in an arbitrary direction for each pixel of image data to be formed and information of each pixel of the image data;

)의 인접 화소 정보들과 튜닝계수들을 독출하여 인접화소들간의 간섭정도를 나타내는 간섭치(

)를 계산하는 간섭치(

) 계산과정과,A pixel to be compensated among the stored pixel information (

The interference value representing the degree of interference between adjacent pixels by reading adjacent pixel information and tuning coefficients of

) To calculate the interference (

) Calculation process,

)와 임계치(T)와의 비교결과에 따라 레이저 다이오드의 출력 주기를 가감시키는 레이저 출력 조절과정으로 이루어짐을 특징으로 한다.
The calculated interference value (

) And a laser output adjustment process for adjusting the output period of the laser diode according to the comparison result with the threshold value T.

Hereinafter, an operation according to an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a diagram illustrating an example of a scanning direction of a general laser beam printer, and illustrates a correlation coefficient between a pixel D to be compensated and pixels adjacent thereto. In Fig. 2, α represents an association coefficient in the horizontal direction, and β and γ each represent an association coefficient in the vertical direction and the oblique direction of the pixel D to be compensated for.

3 is a block diagram of a nonlinear output characteristic compensating apparatus of an image forming system engine according to an exemplary embodiment of the present invention. Referring to FIG. 3, a nonlinear output characteristic compensator of an image forming system engine according to an exemplary embodiment of the present invention includes a controller, a laser power adjusting unit 350, and a laser diode LD, and the laser power adjusting unit 350. ) Is composed of the memory 100, the register 200 and the operation unit 300 again. The register 200 may be embedded in a controller.

)에 가중되는 계수(weighting factor)를 나타낸 것으로, P는 레이저 출력주기를 확장하기 위해 가중되는 계수를 나타낸 것이고, M은 레이저 출력주기를 단축시키기 위해 가중되는 계수이다.Referring to FIG. 3, the controller stores tuning coefficients (α, β, γ, T, P, M) for tuning a laser output cycle for each pixel of image data to be formed, and the printing operation of the printer. Overall control. One of the tuning coefficients T represents a threshold coefficient, and each of P and M is a value that varies according to an energy level characteristic of the laser beam printer engine, and the correlation value calculated by the operation unit 300 (

Is a weighting factor, P is a weighting factor for extending the laser output period, and M is a weighting factor for shortening the laser output period.

The memory 100 is controlled by the controller and stores pixel information of each page data converted by the controller. In the following description, the present invention assumes pixel information having a 3 × 3 matrix structure. An embodiment of the present invention will be described. Pixel information having a 3 × 3 matrix structure can be expressed as shown in Table 1 below.

 Di-1j-1  Dij-1  Di + 1j-1  Di-1j  Dij  Di + 1j  Di-1j + 1  Dij + 1  Di + 1j + 1

The register 200 downloads and temporarily stores the tuning coefficients from the controller, and shows the correlation coefficients of adjacent pixels of the image information D to be compensated as shown in Table 2 below.

  γ   β   γ   α   D   α   γ   β   γ

)들과 튜닝계수들(α,β,γ,T,P,M)을 입력하여 인접화소들간의 연관 정도를 나타내는 연관치(

)를 계산하고, 계산된 상기 연관치(

)와 임계치(T)와의 비교결과에 따라 레이저 다이오드(LD)의 출력 주기를 가감시키기 위한 데이터(

)를 출력한다.The calculation unit 300 may store adjacent pixel information of the pixel D to be compensated from each of the memory 100 and the controller (

) And the tuning coefficients (α, β, γ, T, P, M) to indicate the degree of association between adjacent pixels (

) And calculate the association

) Data for increasing or decreasing the output period of the laser diode LD according to the comparison result of the threshold value T

)

Hereinafter, an operation of the nonlinear output characteristic compensator of the image forming system engine having the above-described configuration will be described in detail with reference to FIGS. 4 and 5.

4 is a flowchart illustrating an operation of a nonlinear output characteristic compensator of an image forming system engine according to an exemplary embodiment of the present invention, and FIG. 5 is a driving diagram of a nonlinear output characteristic compensating apparatus of an image forming system engine according to an exemplary embodiment of the present invention. It is a figure which exemplifies the resulting energy distribution and output image.

)를 산출한다.First, when the print data is input from the host (step 400), the controller converts the data into image data that can be processed by the image forming system. Each pixel information of the image data converted as described above is stored in the memory 100 in operation 420. In this case, the pixel information is information for determining a laser output period before compensation. The controller downloads the tuning coefficients α, β, γ, T, P, and M (step 410) to set the register 200 (step 430). Accordingly, the operation unit 300 calculates the degree of association between the pixel information D to be compensated by Equation 1 and its neighboring pixels in step 440 by using the association value (

) Is calculated.

)를 다운로드된 임계 계수 T와 450단계에서 비교한다. 만약 계산된 연관치(

)가 상기 임계 계수 T 보다 작다면 인접화소간의 연관성이 작은 것이기 때문에 하기 수학식 2를 이용하여 보상하고자 하는 화소의 농도를 높이고(460단계), 그 반대이면 인접화소간의 연관성이 크기 때문에 하기 수학식 3을 이용하여 보상하고자 하는 화소의 농도를 낮춘 다(470단계).Thereafter, the operation unit 300 calculates an association value (calculated by Equation 1 above).

) Is compared with the downloaded threshold coefficient T in step 450. If the computed association value (

) Is smaller than the threshold coefficient T, the correlation between adjacent pixels is small, so that the density of the pixel to be compensated is increased by using Equation 2 below (step 460). Using step 3, the density of the pixel to be compensated for is reduced (step 470).

If the above calculation process is described with specific coefficients as an example, first, if each pixel information of the image data is as shown in Tables 3 and 4 below, and each of the tuning coefficients is set as follows, α = 1, β = 0.5, γ = 0.25 , T = 30, P = 0.005, M = 0.005

   0   0    0   100  100   100    0   0    0

   0   0    0   50  50   50    0   0    0

=50이 되고 그에 따라

는 75(1-0.005×50)가 됨으로써 보상전의 화상 정보(D) 100은 보상후 75의 값을 가지게 되고, 상기 표 4에서는

와

각각이 25와 56.25의 값을 가진다.In Table 3 above

= 50 and accordingly

Is 75 (1-0.005 × 50), so that the image information (D) 100 before compensation has a value of 75 after compensation.

Wow

Each has a value of 25 and 56.25.

FIG. 5 shows a laser diode output period and its energy distribution waveform diagram before information of each pixel of image data is compensated, and a laser diode output cycle and its energy distribution waveform diagram after information of each pixel is compensated. Referring to FIG. 5, it can be seen that the laser diode output period after compensation is shortened at the point where there is energy distribution interference between adjacent pixels before compensation, and the laser diode output period after compensation is extended at the point where the energy distribution interference is low. You can see that.

)에 의해 레이저 다이오드의 출력 주기는 가변되고, 이러한 레이저 다이오드의 출력 주기 가변에 의해 얻어지는 출력화상은 이상적인 출력화상(A)과 거의 동일한 형태를 가지게 되는 것이다.Therefore, the output data (outputted from the calculation unit 300 (

), The output period of the laser diode is variable, and the output image obtained by the variable output period of the laser diode is almost the same as the ideal output image (A).

As described above, the present invention can obtain an optimal output image by compensating the nonlinear output characteristic of the printer engine according to the degree of association between adjacent pixels, and by preventing distortion of the image due to energy interference between adjacent pixels, There is an advantage of obtaining an output image.

Claims (11)

In the nonlinear output characteristic compensation device of an image forming system engine using a laser, A controller which stores tuning coefficients in an arbitrary direction for each pixel of image data to be formed and controls a printing operation of the printer; A memory for storing each pixel information of the image data; Pixels to compensate from each of the memory and the controller (

The interference value representing the degree of interference between adjacent pixels by inputting adjacent pixel information and tuning coefficients of

), And the calculated interference value (

And a laser output adjusting unit configured to add or subtract the output period of the laser diode according to a comparison result between the threshold value T and the threshold value T to print the image according to the image data. The apparatus of claim 1, wherein the image forming system is a color laser beam printer. 2. The apparatus of claim 1, wherein the tuning coefficients comprise tuning coefficients between adjacent pixels in horizontal (α), vertical (β), and diagonal (γ) directions. The method of claim 1, wherein the interference value (

) Is calculated by Equation 4 below.

α, β, and γ are adjacent pixel tuning coefficients in the horizontal, vertical, and diagonal directions, respectively.

Is the pixel you want to compensate (

Adjacent pixel information. The apparatus of claim 1, wherein the laser power adjusting unit; The calculated interference value (

Is greater than the threshold T, the pixel (

Nonlinear output characteristic compensation device of the image forming system engine, characterized in that the laser output cycle for the control) to be shorter than the period before the compensation to be printed. In the nonlinear output characteristic compensation device of a laser beam printer engine, A controller which stores tuning coefficients in an arbitrary direction for each pixel of the image data to be printed and controls a printing operation of the printer; A memory for storing each pixel information of the image data; A register for downloading and storing the tuning coefficients from the controller; The pixel (s)

The interference value representing the degree of interference between adjacent pixels by inputting adjacent pixel information of the pixel and the tuning coefficients

), And the calculated interference value (

And a computing unit for outputting data for changing the output period of the laser diode according to the comparison result between the threshold value T and the threshold value T. The method of claim 6, wherein the interference value (

) Is calculated by the following equation (5).

α, β, and γ are adjacent pixel tuning coefficients in the horizontal, vertical, and diagonal directions, respectively.

Is the pixel you want to compensate (

Adjacent pixel information. The method of claim 7, wherein the interference value (

) Exceeds the threshold value T, the pixel to be compensated (

The laser output period is adjusted to be shorter than the period before compensation, and vice versa, the laser output period is adjusted to be longer than the period before compensation.

Nonlinear output characteristic compensation device of the laser beam printer engine, characterized in that for printing. In the nonlinear output characteristic compensation method of an image forming system engine using a laser, A data input process of inputting and storing tuning coefficients in an arbitrary direction for each pixel of image data to be formed and information of each pixel of the image data; A pixel to be compensated among the stored pixel information (

The interference value representing the degree of interference between adjacent pixels by reading adjacent pixel information and tuning coefficients of

) To calculate the interference (

) Calculation process, The calculated interference value (

And a laser output adjustment process for adjusting the output period of the laser diode according to the comparison result between the threshold value (T) and the threshold value (T). The method of claim 9, wherein the interference value (

) Is calculated by Equation (6) below.

α, β, and γ are adjacent pixel tuning coefficients in the horizontal, vertical, and diagonal directions, respectively.

Is the pixel you want to compensate (

Adjacent pixel information. 10. The method of claim 9, wherein the calculated interference value (

Is less than or equal to the threshold T, the pixel to be compensated (

And adjusting the laser output period longer than the period before compensation to print.

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