Abstract:
A test apparatus having an auto probe and a test method using the same reduces difficulties in defect detection which are caused by a manual test by operators. The test apparatus includes an auto probe unit that contacts a panel of a display device. A test pattern is input to the panel. A vision unit installed above the panel collects a pattern displayed on the panel. A computer system analyzes and determines information about the collected pattern. Whereas the panel was previously tilted from a horizontal position and then examined by the operator manually, in the present test method a movable camera installed at an auto probe apparatus permits testing while the panel is in the horizontal position.

Description:
PRIORITY CLAIM 
     The present application claims the benefit of Korean Application No. 2004-39352 filed on May 31, 2004, which is hereby incorporated by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to a test apparatus having an auto probe and a test method using the same, and more particularly, to a test apparatus having an auto probe and a test method using the same which improve efficiency of a testing operation and a yield as the size of a module increases by installing a camera at an auto probe apparatus used for a cell check and performing a test in a horizontal direction. 
     DESCRIPTION OF THE RELATED ART 
     As interest in information displays and demand for portable information media increases, research and commercialization on light, thin film type flat panel display devices replacing traditional Cathode Ray Tubes (CRT) type display devices is actively being conducted. In particular, a liquid crystal display (LCD) device displays an image using optical anisotropy of liquid crystals, and is actively being applied to notebooks, desktop monitors or the like because it has an excellent resolution, color rendering capability and picture quality. 
     The LCD device includes an array substrate, a color filter substrate and a liquid crystal layer formed therebetween. 
     The array substrate includes gate lines and data lines horizontally and vertically arranged on the substrate to thereby define pixel regions, a thin film transistor (TFT), which is a switching device formed at a crossing of the gate line and the data line, and a pixel electrode formed on the pixel region. 
     In addition, the color filter substrate includes a color filter including sub-color filters R, G and B for implementing a color, a black matrix for dividing the sub-color filters and shielding light transmitting the liquid crystal layer, and a transparent common electrode for supplying a voltage to the liquid crystal layer. 
     The array substrate and the color filter substrate having such a construction are attached to each other by a sealant to thereby construct a liquid crystal display panel. The two substrates are attached to each other by means of an attachment key formed on the array substrate or the color filter substrate. 
     Such a liquid crystal display device is fabricated through an array substrate, a color filter process, a liquid crystal cell process and a module process. 
     In the array process, a thin film transistor array is fabricated on a first substrate by repeating deposition, photolithography and etching processes. In the color filter process, a black matrix is formed on a second substrate so as to shield light on all parts except for the pixel regions, color filters of red (R), green (G) and blue (B) are fabricated using dyes or paints, and then a common electrode is formed. 
     In addition, in the liquid crystal cell process, the first substrate where the thin film transistor forming process is completed and the second substrate where the color filter process is completed are attached to each other with an uniform cell gap maintained therebetween and liquid crystals are injected between the first substrate and the second substrate, thereby forming a liquid crystal display panel cell. In the module process, a circuit unit for processing a signal is fabricated and the liquid crystal display panel and the circuit unit are connected and attached to each other by a mounting technique, thereby fabricating a module. 
     Hereinafter, with reference to the accompanying drawings, a general liquid crystal cell process will be described in more detail. 
       FIG. 1  is a flowchart illustrating a fabrication process of a general liquid crystal display device, wherein a liquid crystal cell process is sequentially illustrated. 
     First, after alignment layers are formed on an array substrate and a color filter substrate, respectively, which are fabricated through an array process and a color filter process, an alignment layer process of providing liquid crystal molecules of a liquid crystal layer formed between the array substrate and the color filter layer with an anchoring force or a surface fixing force is performed (S 101 ). The alignment process is performed in the order of washing before applying an alignment layer, printing the alignment layer, testing the alignment layer, and rubbing. 
     After the array substrate and the color filter substrate are cleaned (S 102  and S 103 ), spacers for maintaining a uniform cell gap are dispersed onto the array substrate, a sealant is applied on an outer portion of the color filter substrate, and then pressure is applied to the array substrate and the color filter substrate, so that the array substrate and the color filter substrate are attached to each other (S 104  to S 106 ). 
     The array substrate and the color filter substrate are formed of a large-area glass substrate. In other words, since a plurality of panel regions are formed on the large-area glass substrate and the thin film transistor and the color filter are formed on each of the panel regions, the glass substrate is cut and processed in order to fabricate separate liquid crystal panels (S 107 ). 
     Finally, after liquid crystal molecules are injected into each of the above-processed liquid crystal display panels through a liquid crystal injection hole and a liquid crystal layer is formed by sealing the liquid crystal injection hole (S 108 ), the test process is applied to determine whether or not each of the liquid crystal panels has a defect in appearance or an electrical defect to thereby fabricate a liquid crystal display panel (S 109 ). An additional procedure of checking a state of the fabricated liquid crystal display panel by performing a defect test is performed to finish the cell process. 
     The final test is an auto probe test for a defect test to determine whether the defect in appearance or the electrical defect exists. The process tests, for example, for the existence of protrusion of the color filter, biased stain, a rubbing stripe, a pin hole, or a disconnection or short circuit of the gate and data lines. However, since in the conventional art, most of tests are performed manually by eye, it takes long time to test a large quantity of liquid crystal display panels and there is a limit of accuracy, thereby degrading operability for performing the above-described test. 
     That is, in the conventional art, a panel transferred to a table through a loader is inclined by 60 degrees for a manual test by the operator. The panel is moved upward and downward to come in contact with a probe unit, whereby the test is performed manually by eye. 
     Defects such as a point defect (PD), a line defect (LD) and a stain are detected by the manual test. According to operators&#39; states and working environments, defect detection may not be appropriately performed and, especially as the difficulty increases with the increasing size of the substrate. Since a panel test is performed with the operators&#39; eyes, the limitations of the test occur as the resolution and size of the model increase, and operation efficiency is lowered because of operators&#39; cumulative fatigue. 
     SUMMARY OF THE INVENTION 
     A test apparatus having an auto probe and a test method using the same are presented which improve efficiency of a testing operation and yield as the size of a module increases by installing a camera at the auto probe and performing a test in a horizontal method, not in a tilt method. 
     By way of introduction only, as embodied and broadly described herein, in one embodiment a test apparatus is provided. The test apparatus comprises an auto probe unit contacting a panel and inputting a test pattern to the panel. A vision unit is installed over the panel and collects a pattern displayed on the panel. A computer system analyzes and determines information about the collected pattern. 
     In another embodiment, an auto probe test method comprises: loading an auto probe unit with a panel for testing; inputting a pattern signal to the panel through the auto probe unit; collecting a pattern displayed on the panel according to the inputted signal using a vision apparatus; and analyzing information about the collected pattern using a computer system and determining whether the panel has a defect or not. 
     In another embodiment, a method of automatically testing a panel of a display device comprises: conveying the panel to a testing location; connecting multiple probes to circuitry on the panel after the panel reaches the testing location; supplying a set pattern of signals to the circuitry through the probes; collecting a display pattern displayed on the panel resulting from supply of the set pattern; and determining whether the panel has a defect from the collected pattern. 
     The foregoing and other features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. 
       In the drawings: 
         FIG. 1  is a flowchart illustrating a fabrication process of a general liquid crystal display device; 
         FIG. 2  is an exemplary view schematically illustrating a test apparatus having an auto probe in accordance with embodiment of the present invention; 
         FIG. 3  is an enlarged exemplary view illustrating an auto probe unit of the test apparatus having the auto probe illustrated in  FIG. 2 ; and 
         FIGS. 4A and 4B  are flowcharts respectively illustrating a method for detecting a defect using the test apparatus having the auto probe in accordance with the embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. 
     Hereinafter, the preferred embodiment of a test apparatus having an auto probe and a test method using the same in accordance with the present invention will be described in detail with reference to the accompanying drawings. 
       FIG. 2  is an exemplary view schematically illustrating a test apparatus having an auto probe in accordance with an embodiment of the present invention. 
     As illustrated therein, a test apparatus having an auto probe for testing a liquid crystal display device after finishing a cell process includes an auto probe unit  300  contacting a panel  400  and inputting a check pattern to the panel  400 ; a vision unit  100  having a vision apparatus such as a camera  600  for detecting a pattern displayed on the panel  400 ; and a computer system  700  for analyzing a signal inputted to the camera  600 . 
     The camera  600  above the panel  400  scans the panel  400  in a horizontal direction, collects a pattern for testing which is inputted by the auto probe unit  300  and displayed on the panel  400 , and transmits the collected pattern for testing to the computer system  700 . The camera  600  may include a CCD (charge coupled device) camera  600 . 
     The camera  600  is operated within a predetermined angular range (e.g., 0 to 7 degrees, 80 to 100 degrees and 110 to 160 degrees) in order to provide complement defect detection varying according to a viewing angle, thereby improving defect testing power by performing a test according to the above-described method. 
     By installing the vision apparatus such as the camera  600  at the test apparatus having the auto probe, the limitations of the test performed by the operators&#39; eyes are complemented to thereby improve operation efficiency and productivity because of the number of defective modules decreases. 
     Meanwhile, an auto probe unit  300  in contact with the panel  400  is installed on a support member  200 , and a driving apparatus  500  is installed on the support member  200  in order to load/unload the panel  400  onto/from the auto probe unit  300  and drive the support member  200  in every direction. 
     When the panel  400  is loaded onto the support member  200  in a conveyor logistics system and a test is performed in a horizontal direction using the vision apparatus, a loader unit used for the existing 60 degree tilt method can be eliminated. That is, since the test can be performed in the horizontal direction, the panel  400  for testing can rest on the auto probe unit  300  of the supporting member  200  in the horizontal direction in the logistics system such as the conveyor. Thus, jobs such as inclining the panel by 60 degrees after transferring the panel  400  for testing to a table through the loader, and contacting the panel with the probe unit  300  by moving it upward and downward can be eliminated. 
     Hereinafter, the auto probe unit will be described in detail with reference to the accompanying drawing. 
       FIG. 3  is an enlarged exemplary view illustrating the auto probe unit of the test apparatus having the auto probe illustrated in  FIG. 2 . 
     As illustrated therein, the auto probe unit  300  is provided with gate needles  310  and data needles  320  for electrically connecting with gate lines (not shown) and data lines (not shown) of each unit panel  400 . The gate needle  310  and the data needle  320  connect with the gate line and the data line, respectively, of the unit panel  400 . The gate needle  310  and the data needle  320  are arbitrarily supplied with voltages, thereby performing a test for determining whether or not the unit panel  400  has a defect in appearance or an electric defect before the module process of connecting a driving circuit for driving the panel  400 . The gate needles  310  and the data needles  320  accurately come in contact with pads (not shown) of the gate lines and the data lines. 
     That is, in the auto probe test, the test for determining whether the unit panel  400  has a defect in appearance or an electric defect is performed by arbitrarily supplying voltages to the gate needles  310  and the data needles  320 . The gate needles  310  and the data needles  320  are controlled to accurately come in contact with the pads of the gate line and the data line. 
     As mentioned above, the test apparatus having the auto probe in accordance with the embodiment of the present invention includes: the auto probe unit  300  provided with a plurality of needles  310  and  320  for inputting a set pattern to the panel  400  for testing and performing a defect test of the unit panel  400 ; the camera  600  located above the auto probe unit  300  and collecting a pattern displayed on the panel  400  through a scan in the horizontal direction; and the computer system  700  receiving information from the camera  600  and analyzing and determining whether or not a desired pattern is displayed. 
     The test apparatus having the auto probe having such a construction can perform a stable auto probe test by preventing deterioration in operability which is caused by the traditional manual work. 
     Hereinafter, a test method using the test apparatus having the auto probe having such a construction, for example, will be described. 
       FIGS. 4A and 4B  are flowcharts respectively illustrating a method of detecting a defect using the test apparatus having the auto probe in accordance with the embodiment of the present invention. 
     First,  FIG. 4A  shows a method of performing a test when the angle of the camera is fixed. An auto probe test starts as a unit panel for testing rests on an auto probe unit of a supporting member by a transfer method using a conveyor in a horizontal direction (S 201 ). 
     The panel for testing is controlled to allow a gate pad and a data pad to accurately come in contact with gate needles and data needles, respectively. 
     Thereafter, a pattern signal for the test is inputted through the gate pad and the data pad of the panel which are in contact with a plurality of needles of the auto probe unit (S 202 ). 
     Such an auto probe test is a process of testing a check stain, a black stain, a color filter protrusion, a bias spot, a rubbing stripe, a pin hole, a disconnection or a short circuit of the gate line and the data line or the like. The test is performed through the auto probe unit according to set items. 
     Thereafter, a pattern displayed on the panel according to the inputted signal is scanned by horizontally moving the vision apparatus provided with the camera thereon, thereby collecting the pattern (S 203 ). 
     The collected pattern information is analyzed and determined using an information processing device such as a computer. By repeating the above-described processes of repetitive input of set patterns with respect to several items, analysis and determination, the test is completed (S 204 ). 
       FIG. 4B  shows a method of performing a test when the angle of the camera is changed in order to detect a defect according to a viewing angle. As described above, the auto probe test starts as the unit panel for testing rests on the auto probe unit of the supporting member by a transfer method using a conveyor in a horizontal direction (S 301 ). 
     Thereafter, a pattern signal for the test is inputted through the gate pad and the data pad of the panel which are in contact with a plurality of needles of the auto probe unit (S 302 ). 
     Then, the angle of the camera of the vision unit is changed in order to detect a defect according to the viewing angle (S 303 ). Defect testing power can be improved by performing the test by changing an angular range of the camera to 0 to 70 degrees, 80 to 100 degrees, 110 to 160 degrees or the like according to the viewing angle of the panel. 
     In addition, the number of cameras installed according to the embodiment of the present invention and an operation method thereof can be appropriately controlled according to the size and resolution of the panel for testing. 
     Thereafter, the pattern displayed on the panel according to the inputted signal is scanned by horizontally moving the vision unit provided with the camera thereon, thereby collecting the pattern (S 304 ). 
     The collected pattern information is analyzed and determined using an information processing device such as a computer. By repeating the above-described processes of repetitive input of set patterns with respect to several items, analysis and determination, the test is completed (S 305 ). 
     As described so far, the test apparatus having the auto probe and the method of testing using the same in accordance with the present invention can improve operators&#39; efficiency and yield by improving the limitations of a manual test as the size of a module increases by automatically testing a panel using a camera, rather than the operator&#39;s eyes. 
     In addition, the present invention can improve defect detection according to the viewing angle by performing a test in a horizontal method, not in a tilt method and by changing camera angles. 
     As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalence of such metes and bounds are therefore intended to be embraced by the appended claims.