Abstract:
A noisy signal analysis in which a threshold value is set to evaluate the presentation of the display device. The analysis can produce the range of noise level of the image for measuring the distortion block of image caused by the display devices. Furthermore, the apparatus includes a step function generator for producing step functions, a transforming unit for changing threshold value in step functions, and a display for showing the image corresponding to both the high value and low value.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a method and an apparatus of noisy signal analysis, and more especially, to a method and an apparatus of noisy signal analysis applied to the liquid crystal display (LCD).  
         [0003]     2. Background of the Related Art  
         [0004]     Currently, since the liquid crystal display (LCD) is booming in IT industry, the monitors of PC have shifted from CRT to the LCD, moreover, the price of LCD is declining very quickly than expected. Although the LCD has a big screen advantage in flat shape, some disadvantages still exist, for example, color temperature, visible angle, contrast, response time and so on.  
         [0005]     The LCD manufacturing processes include: array, cell, and assembly, all these processes encounter many component and assemblies. At end products, the test and adjustment are needed due to low stability of processes, the test includes gray test, brightness test, then the electrical adjustment for characteristic, sometimes, the screen displays have noisy signal unseen from human eyes, such as flicker.  
       SUMMARY OF THE RELATED ART  
       [0006]     In order to solve the problems mentioned above, the present invention provides a method of noisy signal analysis applied to a liquid crystal display. The method adjusts a threshold in a step function and obtains a noisy signal range, which may provide the information to tune the gray value and brightness for the LCD.  
         [0007]     In order to solve the problems mentioned above, the present invention provides an apparatus of noisy signal analysis applied to a liquid crystal display. The apparatus adjusts the gray value and brightness for the LCD to observe the noisy range, and provides test person to measure the LCD quality.  
         [0008]     Accordingly, one embodiment of the present invention provides a method of noisy signal analysis, including: setting a predetermined step function, which changes each signal in a signal group to a first identical value; changing a threshold value of the predetermined step function to a first threshold value which induces a first step function, wherein the first step function changes a signal in the signal group from becoming the first identical value to becoming a second identical value; and continuing changing the first threshold value of the first step function to a second threshold value which induces a second step function, wherein the second step function changes all signals in the signal group from becoming the first identical value to becoming the second identical value.  
         [0009]     Additionally, another embodiment of the present invention provides a method of noisy signal analysis, including: setting a first step function having a first threshold value, and the first step function changes each signal in a signal group to a first identical value, wherein the first threshold value changes a specified quantity causing the first signal in the signal group from becoming the first identical value to becoming the second identical; and setting a second step function having a second threshold value, and the second step function changes each signal in a signal group to a second identical value, wherein the second threshold value changes the specified quantity causing the second signal in the signal group from becoming the second identical value to becoming the first identical value; wherein the signal group has noisy distribution between the first threshold value and the second threshold value.  
         [0010]     Furthermore, another embodiment of the present invention provides an apparatus of noisy signal analysis, including: a step function generator generating a plural step functions, which comprises a first step function having a first threshold value and a second step function having a second threshold value; a transforming unit changing each signal in a signal group to a first identical value according to the first step function and changing every signal of the signal group to the second identical value according to the second step function, wherein the first threshold value changes a specified quantity causing the first signal in the signal group from becoming the first identical value to becoming the second identical, and the second threshold value changes the specified quantity causing the second signal in the signal group from becoming the second identical value to becoming the first identical value; and a display device outputting a range of noisy distribution according to the first threshold value and the second threshold value. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is a functional diagram of the apparatus of noisy signal analysis in accordance with an embodiment of the present invention.  
         [0012]      FIG. 2  is a flow chart of the method of noisy signal analysis in accordance with an embodiment of the present invention.  
         [0013]      FIG. 3  is another flow chart of the method of noisy signal analysis in accordance with an embodiment of the present invention.  
         [0014]      FIG. 4  illustrates the original image curve displayed on the LCD.  
         [0015]      FIG. 5  illustrates the gamma curve of  FIG. 4  in accordance with an embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0016]     A method and an apparatus of noisy signal analysis are disclosed. The invention uses a threshold value in a predetermined step function to test signal appearance in an image displayed on a screen of Flat Panel Display (FPD), whereupon, a noisy distribution will be obtained for noisy signal analysis for that FPD.  
         [0017]      FIG. 1  is a functional diagram of the apparatus of noisy signal analysis in accordance with an embodiment of the present invention. The apparatus of noisy signal analysis includes: a step function generator  12  generates a plural step functions according to a gamma correction function. The step function generator  12  includes a first step function having a first threshold value and a second step function having a second threshold value; a transforming unit  14  changes each signal in a signal group to a first identical value according to first step function and every signal of the signal group to the second identical value according to the second step function. The first threshold value changes a specified quantity causing the first signal in the signal group from becoming the first identical value to becoming the second identical, and the second threshold value changes the specified quantity causing the second signal in the signal group from becoming the second identical value to becoming the first identical value; and a display device  16  outputs a range of noisy distribution according to the first threshold value and the second threshold value.  
         [0018]     Accordingly, The first identical value is greater than the second identical value, and the first threshold value is smaller than the second threshold value. The way of changing the first threshold value is increased with the specified quantity, and the way of changing the second threshold value is decreased with the specified quantity.  
         [0019]     In another embodiment, the first identical value is smaller than the second identical value, and the first threshold value is greater than the second threshold value. The way of changing the first threshold value is decreased with the specified quantity, and the way of changing the second threshold value is increased with the specified quantity.  
         [0020]     Additionally, the display device  16  may be a flat panel display (FPD) or a liquid crystal display (LCD).  
         [0021]      FIG. 2  is a flow chart of the method of noisy signal analysis in accordance with an embodiment of the present invention. The method of noisy signal analysis includes following steps: in step S 10  setting a predetermined step function. Two identical values, a high value (HVAL) and a low value (LVAL) of gray level on a image signal of the display device are set up. The HVAL is greater than LVAL, and the predetermined step function changes each signal value in the group of image signal to the HVAL; In step S 11  setting a threshold value in the predetermined step function to induce a first step function, the threshold value of the predetermined step function is increased to a first threshold value which induces a first step function, wherein the first step function changes a signal value in the signal group from becoming the HVAL to becoming the LVAL. The first threshold value is the lower bound of the image signal; in step S 12  setting a threshold value in the first step function to induce another step function, the first threshold value in step S 11  is continually increased to a second threshold value which induces a second step function, wherein the second step function changes all signal in signal group from becoming the HVAL to becoming the LVAL. The second threshold value is the upper bound of the image block and is greater than the first threshold value; in step S 13  obtaining a noisy signal range, a range between the upper bound and the lower bound is obtained for noisy signal range of the image on display device.  
         [0022]     Furthermore, changing the threshold value causing the signal in the image signal from LVAL to HVAL using the flowchart of  FIG. 2  is another method of noisy signal analysis in accordance with an embodiment of the present invention. The method of noisy signal analysis includes following steps: in step S 10  establishing a predetermined step function. Two identical values, a low value (LVAL) and a high value (HVAL) of gray level on a image signal of the display device are set up. The HVAL is greater than LVAL, and the predetermined step function changes each signal value in the group of image signal to the LVAL; in step S 11  setting a threshold value in the predetermined step function to induce a first step function, the threshold value of the predetermined step function is decreased to a first threshold value which induces a first step function, wherein the first step function changes a signal value in the signal group from becoming the LVAL to becoming the HVAL. The first threshold value is the upper bound of the image signal; in step S 12  setting a threshold value in the step function to induce another step function, the first threshold value in step S 11  is continually decreased to a second threshold value which induces a second step function, wherein the second step function changes all signal in signal group from becoming the LVAL to becoming the HVAL. The second threshold value is the lower bound of the image block and is smaller than first threshold value; in step S 13  obtaining a noisy signal range, a range between the upper bound and the lower bound is obtained for noisy signal correction of the image on display device.  
         [0023]     Additionally, the display device may be a flat panel display (FPD) or a liquid crystal display (LCD).  
         [0024]      FIG. 3  is a flow chart of the method of noisy signal analysis in accordance with another embodiment of the present invention. The method of noisy signal analysis includes following steps: S 20  setting a first step function having a first threshold value, and the first step function changes each signal in a signal group to a first identical value, wherein the first threshold value changes a specified quantity causing the first signal in the signal group from becoming the first identical value to becoming the second identical; and S 21  setting a second step function having a second threshold value, and the second step function changes each signal in a signal group to a second identical value, wherein the second threshold value changes the specified quantity causing the second signal in the signal group from becoming the second identical value to becoming the first identical value; wherein the signal group has noisy distribution between the first threshold value and the second threshold value.  
         [0025]     Accordingly, first identical value is greater than second identical value, and the first threshold value is smaller than the second threshold value. The way of changing the first threshold value is increased with the specified quantity, and the way of changing the second threshold value is decreased with the specified quantity. In another embodiment, first identical value is smaller than second identical value, and the first threshold value is greater than the second threshold value. The way of changing the first threshold value is decreased with the specified quantity, and the way of changing the second threshold value is increased with the specified quantity.  
         [0026]     Accordingly, the gamma correction function may be used as the step function in the invention.  FIG. 4  illustrates the original image curve  30  displayed on the LCD. In applying the invention, the  FIG. 5  illustrates the gamma curve of  FIG. 4  in accordance with an embodiment of the present invention. Firstly, setting HVAL  41  and LVAL  42 ; secondly, setting a threshold value and increasing threshold valve until lower bound (LB)  43  value displayed in the image block; next, continually increasing the threshold value until all image block display upper bound (UB)  44  value; finally, the range between lower bound value and upper bound value is used for gray noisy signal in display device.  
         [0027]     Furthermore, the invention is not limited to the gamma correction function, further the Look Up Table (LUT), polynomial function, and piecewise interpolation may be used and make the present invention displays noisy signal effectively for checking the defects of the display device.  
         [0028]     Although the present invention has been explained in relation to its preferred embodiment, it is to be understood that other modifications and variation can be made without departing the spirit and scope of the invention as hereafter claimed.