Abstract:
A testing circuit and a test method for a liquid crystal display device are provided. The testing circuit for the liquid crystal display device employs p shorting bars to test subpixels of pixel cells formed on a substrate. The p shorting bars are respectively connected to (p×m+1)th, (p×m+2)th, (p×m+3)th . . . , (p×m+p)th numbered signal paths of the plurality of the signal paths, and when n is odd, p=2×n; when n is even, p=n; with m being zero or a positive integer.

Description:
FIELD OF THE INVENTION 
   The present invention relates to a testing circuit and a method for liquid crystal display device, in particular a testing circuit and a method for liquid crystal display device by grouping signal paths according to the number of pixels. 
   BACKGROUND OF THE INVENTION 
   In the front end of manufacturing liquid crystal display (LCD) devices, millions of thin film transistors (TFT), usually formed on a substrate using epitaxial method, control pixels on the displaying structure wherein the substrate can be a glass substrate, a flexible substrate or a silicon substrate. Dark points or luminous points, i.e. defective display pixels, are shown if a portion of the TFT transistors do not function well due to the defects created during the manufacturing process. These defective pixels downgrade the quality of TFT display devices substantially and become an important objective of the TFT transistor testing. 
   Referred to  FIG. 1 , it is a diagram of a testing circuit of an LCD in prior art, comprising, formed on a substrate, a plurality of signal paths  11  in parallel and a plurality of gate signal paths  12  in parallel. It further comprises a TFT transistor at the cross point of the signal paths  11  and gate signal paths  12  acting as a control unit of the pixel  131  of the pixel cell  13 . The pixel cell  13  usually contains three pixels  131 , each corresponding to red (R), green (G), and blue (B) colors, showing colors by mixing these three colors according to an appropriate ratio of the strengths of these primary three colors. Furthermore, testing equipments can test the LCD by coupling probes with testing pads  111  of signal paths  11  and with testing pads  121  of gate signal paths  12 . 
   While testing the characteristics of a specific TFT transistor, it is often to couple the testing pads  111  of signal paths  11  of the specific TFT transistor with a first testing probe of the testing equipment and couple the testing pads  121  of gate signal paths  12  of the specific TFT transistor with a second testing probe of the testing equipment. The testing equipment sends testing signals through the first testing probe, second testing probe, signal paths  11  and gate signal paths  12  into the specific TFT transistor for verifying the characteristics and quality with normal standards. 
   The testing method mentioned above needs a long testing time because it requires time to move the two testing probes to attach on each pair of specific testing pads  111 ,  121 . Although the time can be reduced by increasing the number of testing probes of the testing equipment, it is still not a practicable method while considering the raising cost. 
   Referred to  FIG. 2 , it is a diagram of another testing circuit of an LCD in prior art providing another method to solve the problem occurred in the testing circuit described in  FIG. 1  wherein a shorting bar  21  is connected to all of the signal paths  11  and a gate shorting bar  22  is connected to all of the gate signal paths  12 . A testing pad  211  connected to one terminal of the shorting bar  21  and a testing pad  221  connected to one terminal of the gate shorting bar  22  are utilized for coupling with the testing probes of the testing equipment. During the testing process, after coupling a first testing probe of the testing equipment with the testing pad  211  of the shorting bar  21  and coupling a second testing probe of the testing equipment with the testing pad  221  of the gate shorting bar  22 , the testing equipment sends testing signals by the first testing probe and the second testing probe through the shorting bar  21  and the gate shorting bar  22  into all of the TFT transistors. By driving the TFT transistors on the LCD panel further converts the testing signals to light signals. If there were portions of TFT transistors not being driven successfully result from defects during manufacturing process, the optical inspecting system of the testing equipment can screen them out and save the testing time apparently. The manufacturing process is completed after the shorting bar  21  and the gate shorting bar  22  is further dismembered from signal paths  11  and signal paths  12 . 
   The method mentioned above still can not screen out the defects due to the short defects created during manufacturing process of any two adjacent signal paths among signal paths  11  or signal paths  12 . This problem can be solved by dividing the signal paths  11  and gate signal paths  12  into several groups and connecting each group to corresponding shorting bar. 
   Referred to  FIG. 3 , it is a diagram of further one testing circuit of an LCD in prior art. The testing circuit in  FIG. 3  is usually called 2G2D testing circuit, i.e. 2 gates and 2 drains, for solving the problem not able to inspect the short defects between any two adjacent signal paths among signal paths  11  or signal paths  12 . The testing circuit in  FIG. 3  comprises a plurality of signal paths  11 ; a plurality of gate signal paths  12 ; two shorting bars  31  each connected to odd number signal paths  32  and even number signal paths  33 ; two gate shorting bars  34  each connected to odd number signal paths  35  and even number signal paths  36 . Testing pads  311 ,  341  for coupling with the testing probes of the equipment are connected to shorting bars  31  and gate shorting bars  34  respectively. While testing, the testing equipment sends testing signals through the shorting bars  31  and the gate shorting bars  34  into preferred portions of TFT transistors by coupling multiple testing probes with corresponding testing pads  311 ,  341 . Within this method, any two adjacent signal paths among signal paths  11  or gate signal paths  12  are connected to different groups of shorting bars, and any short defects between any two adjacent signal paths can be screened out. 
   There are often short defects between two adjacent signal paths during the manufacturing process of array cells. The testing method in  FIG. 3  is an effective way to screen out those short defects between two adjacent signal paths but only suitable for the array testing of LCD devices. During the manufacturing process of liquid crystal cells, color filters are coupled with the substrate and liquid crystal molecules are injected into the substrate. Thus, the testing signals are converted through the liquid crystal cells into light signals and further into light with red, green or blue color corresponding to the three pixels of a liquid crystal cell. Normally, a liquid crystal cell contains three pixels with three primary colors including red, green and blue color and produces images by controlling the light intensities of these three pixels to create desirable colors like purple, yellow, cyan etc. While testing the LCD devices after the step of manufacturing liquid crystal cells, the most effective way for inspecting the LCD devices is to first divide the pixels with color filters into groups according to their primary colors of a liquid crystal cell. The sequential number of the signal paths can be divided into three groups corresponding to three primary colors and thus connected to the corresponding shorting bar. 
   Referred to  FIG. 4 , it is a diagram of further another testing circuit of an LCD in prior art. The testing circuit in  FIG. 4  is to improve the testing efficiency of liquid crystal cells of LCD devices and is usually called 2G3D testing circuit, i.e. 2 gates and 3 drains, comprising a plurality of signal paths  11  on a substrate; a plurality of signal paths  12  on the substrate; three shorting bars  41  on the substrate wherein each one of the three shorting bars is connected to the (3m+1)th signal path  42 , (3m+2)th signal path  43 , (3m+3)th  signal path  44  where m is an positive integral number or zero. It is equal to divide the signal paths into three groups and connected to shorting bars  41  wherein the 1, 4, 7, . . . signal path a signal path group  42 ; the 2, 5, 8, . . . signal path a signal path group  43 ; and the 3, 6, 9, . . . signal path a signal path group  44 . The testing circuit further comprises two gate shorting bars  34  on the substrate wherein each gate shorting bar is connected to odd number gate signal path  35  and even number gate signal path  36 . Furthermore, testing pads  411 ,  341  are connected to one end of the corresponding shorting bars  41  and one end of gate shorting bars  34  for coupling with the testing probes of testing equipments. While testing, testing equipments send testing signals into specific TFT transistors through the shorting bars  41  and gate shorting bars  34  by coupling a plurality of testing probes with a plurality of corresponding testing pads  411 ,  341 . In this testing method, the signal paths  11  are already divided into three groups corresponding to their primary color, and can improve the testing performance by inputting testing signals into specific shorting bars  41  and then inspecting the primary color shown on the specific pixels connected to the specific shorting bars  41 . This method is suitable for testing pixels at the step after completing the manufacturing process of liquid crystal cells. However, the disadvantage of this method is that the testing time is obviously increased for including the short defects examination of any two adjacent signal paths  11 . The short defects examination of any two adjacent signal paths  11  is to test all possible combinations of any two signal paths selected from the (3m+1)th signal path  42 , (3m+2)th signal path  43 , and (3m+3)th signal path  44 . 
   As mentioned above, neither of the testing efficiency of array testing or the testing efficiency of liquid crystal cell testing can be improved simultaneously no matter the testing circuit of an LCD in  FIG. 3  or the testing circuit of an LCD in  FIG. 4  is applied. The testing efficiency of liquid crystal cell testing decreases by applying the testing circuit in  FIG. 3 , and in the same way the testing efficiency of array testing reduces by applying the testing circuit in  FIG. 4 . In the rapid progress of LCD industry, the competitive ability includes avoiding the increasing testing time and delaying shipping schedule due to inappropriate testing methods. The competitive ability is further strengthened by providing a solution to solve the testing problems mentioned above. 
   Therefore, it is an object of the present invention to provide one testing circuit by including additional shorting bars whose number is multiple of the number of pixels in a liquid crystal cell. The problems of the testing efficiency in steps at array testing and at liquid crystal cell testing can be both improved effectively according to the present invention. 
   SUMMARY OF THE INVENTION 
   The present invention provides a testing circuit, comprising a substrate; a plurality of pixel cells on the substrate wherein each pixel cell contains n number pixels; a plurality of signal paths on the substrate connecting to the corresponding pixels; p number of shorting bars on the substrate connecting to (p×m+1)th, (p×m+2)th, (p×m+3)th . . . , (p×m+p)th signal path; where p=2×n while n is an odd integral number and p=n while n is an even number, and m is zero or positive integral number. 
   In one aspect of the present invention, there is provided a testing circuit of an LCD utilizing the testing circuit mentioned above. The p shorting bars are divided into groups by the base number n wherein testing signals are sent into each group of shorting bars respectively. The p shorting bars can also be divided into groups by number 2 wherein testing signals are sent into each group of shorting bars respectively. 
   For example, if n equals to an odd number 3, then the number of shorting bars will be 6 (p=2×3) wherein each of them connects to (6×m+1)th, (6×m+2)th, (6×m+3)th . . . , (6×m+6)th signal path respectively. While testing on the liquid crystal cells during the manufacturing process of an LCD, these 6 shorting bars can be divided into groups based on number 3 which means the first and the forth shorting bars are in a group; the second and the fifth shorting bars are in another group; and the third and sixth shorting bars are in one another group. Thus, testing signals can be sent into the shorting bars belonged to the corresponding group. The inspection can be implemented based on the primary colors because the shorting bars are divided into groups according to the primary colors equal to the number of pixels in a liquid crystal cell. It is an effective way to implement the liquid crystal cells testing. While doing the array testing, testing signals are sent into two groups of shorting bars wherein one of the groups comprises the odd number of the shorting bars among these 6 shorting bars and the other of the groups comprises the even number of the shorting bars among these 6 shorting bars. In this case, the short defects between any two neighboring signal paths can be screened out. 
   For example, if n equals to an even number 4, then the number of shorting bars will be 4 (p=4) wherein each of them connects to (4×m+1)th, (4×m+2)th, (4×m+3)th, and (4×m+4)th signal path respectively. While testing on the liquid crystal cells during the manufacturing process of an LCD, these 4 shorting bars can be divided into groups based on number 4. Thus, testing signals can be sent into the shorting bars belonged to the corresponding group. The inspection can be implemented based on the primary colors because the shorting bars are divided into groups according to the primary colors equal to the number of pixels, i.e. number 4, in a liquid crystal cell. It is an effective way to implement the liquid crystal cells testing. While doing the array testing, testing signals are sent into two groups of shorting bars wherein one of the groups comprises the odd number of the shorting bars among these 4 shorting bars and the other of the groups comprises the even number of the shorting bars among these 4 shorting bars. In this case, the short defects between any two neighboring signal paths can be screened out. 
   While the present invention has been described in detail and pictorially in the accompanying drawings, it is not limited to such details since the similar methods can be implemented as efficient testing methods when the number n equals 5, 6, 7 . . . etc. 
   In another aspect of the present invention, there is provided a testing circuit, comprising a substrate; a plurality of pixel cells on the substrate wherein each pixel cell contains n number pixels; a plurality of signal paths on the substrate connecting to the corresponding pixels; n number of shorting bars on the substrate connecting to (n×m+1)th, (n×m+2)th, (n×m+3)th . . . , (n×m+n)th signal path respectively; where n is an odd integral number and m is zero or positive integral number. 
   With the advantages described above, the present invention provides a testing circuit and a method that improves both the testing efficiency of array testing and the testing efficiency of liquid crystal cells simultaneously, and thus speed up the shipping schedule. Not only make the cost down during the testing process of LCD devices but also have an elastic shipping schedule of LCD devices. The competitive ability in LCD industry is further strengthened 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a diagram of a testing circuit of an LCD in prior art; 
       FIG. 2  is a diagram of another testing circuit of an LCD in prior art; 
       FIG. 3  is a diagram of further one testing circuit of an LCD in prior art; 
       FIG. 4  is a diagram of further another testing circuit of an LCD in prior art; 
       FIG. 5  is a diagram of a testing circuit of an LCD according to the present invention; 
       FIG. 6  is a diagram of another testing circuit of an LCD according to the  FIG. 5 ; 
       FIG. 7  is a diagram of another testing circuit of an LCD according to the present invention; and 
       FIG. 8  is a diagram of further one testing circuit of an LCD according to the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The testing circuit of an LCD device according to the present invention utilizes the concept of grouping the signal paths based on the number of pixels in a pixel cell. In the following preferred embodiments, only the embodiments having the number of pixels in a pixel cell equals to number 3 and number 4 are disclosed. The embodiments with the number of pixels in a pixel cell equals to 5 or more are not described here but any one skilled in the art can implement them according to disclosure of the present invention. 
   Referred to  FIG. 5 , it is a diagram of a testing circuit of an LCD according to the present invention. This embodiment with the number of pixels of a pixel cell equal to number 3, comprising a substrate; a plurality of pixel cells  51  on the substrate wherein each pixel cell  51  contains three pixels  511 ; a plurality of signal paths  52  on the substrate connecting to the corresponding pixels  511 ; six shorting bars  53  on the substrate connecting to (6×m+1)th  521 , (6×m+2)th  522 , (6×m+3)th  523 , (6×m+4)th  524 , (6×m+5)th  525 , and (6×m+6)th  526  signal path; where m is zero or positive integral number. It&#39;s similar to divide the signal paths based on the number 6 into six groups connecting to shorting bars  53  wherein the 1st, 7th, 13th . . . , and etc. signal paths  521  are the first group; the 2nd, 8th, 14th . . . , and etc. signal paths  522  are the second group; the 3rd, 9th, 15th . . . , and etc. signal paths  523  are the third group; the 4th, 10th, 16th . . . , and etc. signal paths  524  are the fourth group; the 5th, 11th, 17th . . . , and etc. signal paths  525  are the fifth group; the 6th, 12th, 18th . . . , and etc. signal paths  526  are the sixth group. The LCD testing circuit according to the present invention further comprises a plurality of gate signal paths  54  on the substrate connecting to the corresponding pixels  511 , two gate shorting bars  55  on the substrate each of them connecting to the odd number gate signal paths  541  and even number gate signal paths  542  respectively and testing pads  531 ,  551  for coupling with probes of testing equipments connecting to terminals of gate shorting bars  55  and terminals of shorting bars  53 . 
   While doing the liquid crystal cells of an LCD testing, the six shorting bars  53  can be divided several groups based on number 3 which means the 1st and 4th shorting bars  532  are a group, the 2nd and 5th shorting bars  533  are another group, and the 3rd and 6th shorting bars  534  are further another group. Thus, testing signals are sent into each group of shorting bars  53  which are divided into groups based on three, the number of pixels in each pixel cell. Each of testing signals is sent into corresponding shorting bars  532 ,  533 ,  534  each connecting to same color of pixels. Finally, the inspection can be implemented by verifying the primary color emitting from pixels and provides an efficient way to carry out the testing of liquid crystal cells of an LCD. While doing the array testing of an LCD, the six shorting bars can be divided into two groups comprising one group with odd number of shorting bars and another group with even number of shorting bars. The short defects between any two neighboring signal paths can be screened out by inputting testing signals into each group of shorting bars. This provides an efficient method for array testing of an LCD. 
   Referred to  FIG. 6 , it is a diagram of another embodiment modified from the testing circuit in  FIG. 5 . The embodiment in  FIG. 6  according to the present invention further comprises a first collecting shorting bar  61  and a second collecting shorting bar  62  on the substrate wherein the shorting bars  53  with odd sequential number couple with the first collecting shorting bar  61  and the shorting bars  53  with even sequential number couple with the second collecting shorting bar  62 . The embodiment further comprises testing pads  611 ,  621 , each connecting to one terminal of the first collecting shorting bar  61  and one terminal of the second collecting shorting bar  62  respectively, for coupling with the testing probes of testing equipments. The six shorting bars  53  are further divided into two groups according to the odd and even sequential number of the shorting bars. While doing the array testing, the short defects between two adjacent signal paths can be effectively inspected by inputting testing signals into the first collecting shorting bar  61  and the second collecting shorting bar  62 . After completing the array testing, dissect the first collecting shorting bar  61  and the second collecting shorting bar  62  from the LCD along the dotted line  63 . Thus, the liquid crystal cells testing can be the next following step of testing process. 
   Referred to  FIG. 7 , it is a diagram of further another testing circuit of an LCD according to the present invention. The embodiment in which contains pixel cells with 4 pixels comprises a substrate wherein the substrate can be a glass substrate or a flexible substrate; a plurality of pixel cells  71  on the substrate wherein each pixel cell  71  contains four pixels  711 ; a plurality of signal paths  72  on the substrate connecting to corresponding pixels  711 ; four shorting bars  73  on the substrate, each of the four shorting bars  73  connects to (4×m+1)th, (4×m+2)th, (4×m+3)th, and (4×m+4)th signal path  721 ,  722 ,  723 ,  724  where m is a positive integer or zero. It&#39;s similar to divide the signal paths based on the number 4 into four groups connecting to shorting bars  73  wherein the 1st, 5th, 9th . . . , and etc. signal paths  721  are the first group; the 2nd, 6th, 10th . . . , and etc. signal paths  722  are the second group; the 3rd, 7th, 11th . . . , and etc. signal paths  723  are the third group; the 4th, 8th, 12th . . . , and etc. signal paths  724  are the fourth group. The LCD testing circuit according to the present invention further comprises a plurality of gate signal paths  74  on the substrate connecting to the corresponding pixels  711 , two gate shorting bars  75  on the substrate each of them connecting to the odd number gate signal paths  741  and even number gate signal paths  742  respectively and testing pads  731 ,  751  for coupling with probes of testing equipments connecting to terminals of gate shorting bars  75  and terminals of shorting bars  73 . While doing the testing, testing equipments send testing signals by coupling a plurality of testing probes with corresponding testing pads  731 ,  751  into shorting bars  73  and gate shorting bars  75 . 
   While doing the liquid crystal cells of an LCD testing, the four shorting bars  73  can be divided several groups based on the number 4 which means four groups. Thus, testing signals are sent into each group of shorting bars  73  which are divided into groups based on four, the number of pixels in each pixel cell. Each of testing signals is sent into corresponding shorting bars with same color of pixels. Finally, the inspection can be implemented by verifying the primary color emitting from pixels and provides an efficient way to carry out the testing of liquid crystal cells of an LCD. While doing the array testing of an LCD, the four shorting bars can be divided into two groups comprising one group with odd number of shorting bars and another group with even number of shorting bars. The short defects between any two neighboring signal paths can be screened out by inputting testing signals into each group of shorting bars. This provides an efficient method for array testing of an LCD. 
   The testing circuit according to  FIG. 7  can be further modified according to the embodiment in  FIG. 6 . The four shorting bars  73  can be connected to a first collecting shorting bar and a second collecting shorting bar according to their odd sequential number or even sequential number. 
   Finally, there is still another testing circuit of an LCD with odd number pixels in a pixel cell according to the present invention. The example illustrated here is for n=5. The rule is the same for n=7, 9, 11 . . . , etc. Referred to  FIG. 8 , it is a diagram of an embodiment according to the present invention. The embodiment in which contains pixel cells with 5 pixels comprises a substrate wherein the substrate can be a glass substrate or a flexible substrate; a plurality of pixel cells  81  on the substrate wherein each pixel cell  81  contains five pixels  811 ; a plurality of signal paths  82  on the substrate connecting to corresponding pixels  811 ; five shorting bars  83  on the substrate, each of the five shorting bars  83  connects to (5×m+1)th, (5×m+2)th, (5×m+3)th, (5×m+4)th, and (5×m+5)th signal path  821 ,  822 ,  823 ,  824 ,  825  where m is a positive integer or zero. It&#39;s similar to divide the signal paths based on number 5 into five groups connecting to shorting bars  83  wherein the 1st, 6th, 11th . . . , and etc. signal paths  821  are the first group; the 2nd, 7th, 12th . . . , and etc. signal paths  822  are the second group; the 3rd, 8th, 13th . . . , and etc. signal paths  823  are the third group; the 4th, 9th, 14th . . . , and etc. signal paths  824  are the fourth group; the 5th, 10th, 15th . . . , and etc. signal paths  825  are the fifth group. The LCD testing circuit according to the present invention further comprises a plurality of gate signal paths  84  on the substrate connecting to the corresponding pixels  811 , two gate shorting bars  85  on the substrate each of them connecting to the odd number gate signal paths  841  and even number gate signal paths  842  respectively and testing pads  831 ,  851  for coupling with probes of testing equipments connecting to terminals of gate shorting bars  85  and terminals of shorting bars  83 . While doing the testing, testing equipments send testing signals by coupling a plurality of testing probes with corresponding testing pads  831 ,  851  into shorting bars  83  and gate shorting bars  85 . 
   With the detail description of the embodiments according to the present invention mentioned above, there is provided a testing circuit able to improve the efficiency of both array testing and liquid crystal cells of an LCD. Although the depiction is about several examples with specific number pixels of a pixel cell, an LCD with any number of pixels of a pixel cell can apply this methodology according to the invention, too. 
   While the present invention has been described in detail, it is not limited to such details since any modifications and changes may be made to those of skill in the art without departing from the spirit and scope of the invention. The features and advantages of the present invention will become apparent from the appended claims.