Patent Publication Number: US-RE49135-E

Title: Flat panel display device, method of aging the same, and method of testing lighting of the same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS AND CLAIM OF PRIORITY 
     This application is a reissue application of U.S. Pat. No. 9,747,831, filed on Jul. 20, 2015 as U.S. patent application Ser. No. 14/804,250 and issued on Aug. 29, 2017, which is a continuation application of the prior application Ser. No. 12/385,153 filed in the U.S. Patent &amp; Trademark Office on Mar. 31, 2009 and assigned to the assignee of the present invention. Furthermore, this application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. § 119 from an application earlier filed in the Korean Intellectual Property Office on 1 Apr. 2008 and there duly assigned Serial No. 10-2008-0030261. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a flat panel display device formed in a pentile structure and having a pixel portion and lighting tester. The lighting tester applies test voltages or aging voltages to the pixel portion. 
     Description of the Related Art 
     Since flat panel display devices are lightweight and thin, they are used as alternatives to cathode-ray tube display devices. Examples of flat panel display devices include liquid crystal display (LCD) devices and organic light emitting diode (OLED) display devices. 
     The OLED display devices generate excitons by recombination of electrons and holes, which are injected through a cathode and an anode, respectively, in an organic thin film, and emit light having a predetermined wavelength due to energy released from the excitons. The OLED display devices have high brightness and a wide viewing angle, and can be embodied in an ultra slim structure because they do not need a backlight. 
     A flat panel display device includes red, green and blue pixels to display full color. When the red, green and blue pixels are arranged in stripes, a boundary portion between pixels is visible as though the pixels were surrounded with a black matrix. Thus, image data of the flat panel display device has to be rendered. 
     Generally, rendering gives a realistic, three-dimensional appearance to an object by tone variation and shading in consideration of external information such as light sources, perspective and color. That is, rendering is an image-processing technique used to display a two- or three-dimensional graphic image. To render its image data, the flat panel display device has to have a plurality of pixels arranged in a pentile structure, which includes a first pixel column, a second pixel column, and a third pixel column. In the first pixel column, first pixels for displaying a first color and second pixels for displaying a second color are alternately arranged in a direction parallel to a plurality of data lines. In the second pixel column, the first pixels and the second pixels are arranged in reverse order of the first pixel column in the direction parallel to the plurality of data lines. In the third pixel column, third pixels for displaying a third color are arranged in the direction parallel to the plurality of data lines. 
     However, in the flat panel display device having a pentile structure described above, since the first and second pixels are always alternately arranged in one scan line due to the first pixel column in which the first and second pixels are alternately arranged in a direction parallel to the plurality of data lines and the second pixel column in which the first and second pixels are arranged in reverse order of the first pixel column in the direction parallel to the plurality of data lines, a first test voltage for testing lighting of the first pixel or a first aging voltage for aging the first pixel, and a second test voltage for testing lighting of the second pixel and a second aging voltage for aging the second pixel are alternately applied to one data line during the lighting test or the aging process. Thus, a brightness difference may be generated between pixels during the lighting test, and pixels might be excessively or insufficiently aged. 
     To solve these problems, it is necessary to either employ additional equipment for testing or aging each pixel, or modify conventional equipment for testing and aging a flat panel display device having a striped structure. Thus, additional costs are incurred for the lighting test and aging process of the flat panel display device having a pentile structure. 
     SUMMARY OF THE INVENTION 
     The present invention provides a flat panel display device which can sufficiently age each pixel of a pixel portion and prevent a brightness difference between pixels during a lighting test, without adding equipment or modifying conventional equipment, by changing a structure of a lighting tester for applying lighting test voltages and aging voltages to the pixel portion through data lines, and lighting test and aging methods for the same. 
     According to an embodiment of the present invention, a flat panel display device includes a scan driver for applying scan signals to a plurality of scan lines, a data driver for applying data signals to a plurality of data lines, a pixel portion, and a lighting tester for applying lighting test voltages or aging voltages to the pixel portion. The pixel portion includes a first pixel column including first pixels for displaying a first color and second pixels for displaying a second color, a second pixel column including first pixels for displaying the first color and second pixels for displaying the second color, and a third pixel column including third pixels for displaying a third color. The first and second pixels of the first column are alternately arranged in a direction parallel to the data lines, and each of the first and second pixels of the first pixel column is coupled to one of the scan lines and one of the data lines. The first and the second pixels of the second pixel column are alternately arranged in reverse order of the first pixel column in a direction parallel to the data lines, and each of the first and second pixels of the second pixel column is coupled to one of the scan lines and one of the data lines. The third pixels are arranged in a direction parallel to the data lines, and each of the third pixels is coupled to one of the scan lines and one of the data lines. The lighting tester applies lighting test voltages or aging voltages to the first, second and third pixel columns. The lighting tester applies a first voltage to the first pixel column and applies a second voltage to the second pixel column during a first time period. The lighting tester applies the second voltage to the first pixel column and applies the first voltage to the second pixel column during a second time period. 
     According to another embodiment of the present invention, a method is provided for testing lighting of a flat panel display device having the structure described above. The method includes steps of electrically connecting the first pixel column to a first test power source and electrically connecting the second pixel column to a second test power source whenever a first control signal is supplied to the lighting tester, electrically connecting the first pixel column to the second test power source and electrically connecting the second pixel column to the first test power source whenever a second control signal is supplied to the lighting tester, and supplying scan signals to the scan lines. The first and second control signals are synchronized with the scan signals. 
     According to still another embodiment of the present invention, a method is provided for aging a flat panel display device having the structure described above. The method includes steps of connecting a first, a second and a third interconnections to a first, a second and a third aging power sources, respectively, electrically connecting the first pixel column to the first interconnection and electrically connecting the second pixel column to the second interconnection whenever a first control signal is supplied to the lighting tester, electrically connecting the first pixel column to the second interconnection and electrically connecting the second pixel column to the first interconnection whenever a second control signal is supplied to the lighting tester, electrically connecting the third pixel column to the third interconnection whenever a third control signal is supplied to the lighting tester, and supplying scan signals to the scan lines. The first and second control signals are synchronized with the scan signals. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete appreciation of the invention, and many of the attendant advantages thereof, will be readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein: 
         FIG. 1  is a schematic view of a flat panel display device according to an exemplary embodiment of the present invention; and 
         FIG. 2  is a timing diagram of scan and control signals applied to a flat panel display device according to an exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference will now be made in detail to the present embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present invention by referring to the figures. 
       FIG. 1  is a schematic view of a flat panel display device according to an exemplary embodiment of the present invention. 
     Referring to  FIG. 1 , the flat panel display device according to the exemplary embodiment of the present invention includes a data driver  110  for applying data signals to a plurality of data lines D 1  to Dm, a scan driver  120  for applying scan signals to a plurality of scan lines S 1  to Sn, a pixel portion  100 , and a lighting tester  140  for applying lighting test voltages or aging voltages to the pixel portion  100 . The pixel portion  100  includes a first pixel column  101  in which first pixels PB for displaying blue color and second pixels PR for displaying red color are alternately arranged in a direction parallel to the plurality of data lines D 1  to Dm, a second pixel column  102  in which first pixels PB and second pixels PR are arranged in reverse order of the first pixel column  101  in the direction parallel to the plurality of data lines D 1  to Dm, and a third pixel column  103  in which third pixels PG for displaying green color are arranged in the direction parallel to the plurality of data lines D 1  to Dm. The lighting tester  140  for applying lighting test voltages or aging voltages to the first, second and third pixel columns  101 ,  102  and  103 . Each of pixels PR, PB, and PG is coupled to one of the data lines D 1  to Dm and to one of scan lines S 1  to Sn. 
     While the exemplary embodiment of the present invention has the first pixels PB for displaying blue color and the second pixels PR for displaying red color alternately arranged in each of the first and second pixel columns  101  and  102 , in alternative embodiments, the first pixels PB for displaying blue color and the third pixels PG for displaying green color, or the second pixels PR for displaying red color and the third pixels PG for displaying green color, may be alternately arranged in each of the first and second pixel columns  101  and  102 . 
     Moreover, while the pixel portion  100  includes the first pixels PB for displaying blue color, the second pixels PR for displaying red color and the third pixels PG for displaying green color in the exemplary embodiment of the present invention, the pixel portion  100  may further include pixels (not illustrated) for displaying one or more colors other than red, green and blue. 
     The data driver  110  receives red, green and blue digital image signals processed by rendering from a timing controller (not illustrated), and generates red, green and blue data signals synchronized with the scan signals generated from the scan driver  120 . The data driver  110  applies the red, green and blue data signals to the pixel portion  100  through the plurality of data lines D 1  to Dm electrically connected with the pixel portion  100 . 
     The scan driver  120  sequentially applies the scan signals to the plurality of scan lines S 1  to Sn electrically connected with the pixel portion  100 , and sequentially selects pixels PB, PR and PG from the first, second and third pixel columns  101 ,  102  and  103  of the pixel portion  100 , respectively. 
     The lighting tester  140  includes a first transistor M 1  coupled between the first pixel column  101  and a first interconnection Vb through which a first voltage for a first pixel PB is supplied, a second transistor M 2  coupled between the first pixel column  101  and a second interconnection Vr through which a second voltage for a second pixel PR is supplied, a third transistor M 3  coupled between the second pixel column  102  and a first interconnection Vb, a fourth transistor M 4  coupled between the second pixel column  102  and the second interconnection Vr, a fifth transistor M 5  coupled between the third pixel column  103  and a third interconnection Vg through which a third voltage for a third pixel PG is supplied, a first control interconnection C 1  through which a first control signal is applied to turn on the first and fourth transistors M 1  and M 4 , a second control interconnection C 2  through which a second control signal is applied to turn on the second and third transistors M 2  and M 3 , and a third control interconnection C 3  through which a third control signal is applied to turn on the fifth transistor M 5 . 
     Here, while all of the first to fifth transistors M 1  to M 5  are illustrated as PMOS transistors in the exemplary embodiment of the present invention, the first to fifth transistors M 1  to M 5  may be NMOS transistors or transistors having different conductivity types from one another. 
     Further, the first, second and third voltages may be lighting test voltages for testing the lighting of the first, second and third pixel columns  101 ,  102  and  103 , respectively, or aging voltages for aging the first, second and third pixels PB, PR and PG, respectively. For the test of the lighting, the first, second and third interconnections Vb, Vr and Vg are connected to a first, second and third test power sources, respectively. For the aging test, the first, second and third interconnections Vb, Vr and Vg are connected to a first, second and third aging power sources, respectively. 
     Since the third voltages have to be sequentially applied to the third pixel column  103  in response to the scan signals, the fifth transistor M 5  and the third control interconnection C 3  may be omitted. However, if duration of application of the first, second or third voltage to pixel PB, PR or PG of the first, second or third pixel column  101 ,  102  or  103  is shorter than duration of application of a scan signal to each of the plurality of scan lines S 1  to Sn (or if a scan signal is applied ahead of the first, second or third voltage applied to the pixel PB, PR or PG), the first, second or third voltage applied to the pixel PB, PR or PG is not sufficiently recorded, which may cause a brightness difference between the pixels PB, PR and PG Thus, it is preferable that the fifth transistor M 5  and the third control interconnection C 3  are included in the lighting tester  140 . 
     In addition, the flat panel display device according to the exemplary embodiment of the present invention may further include an emission controller  130  for applying an emission control signal to the pixel portion  100  to emit light from the first, second and third pixels PB, PR and PG after sufficient lighting test voltages are applied to the first, second and third pixels PB, PR and PG of the pixel columns  101 ,  102  and  103 , respectively, during the lighting test for the first, second and third pixel columns  101 ,  102  and  103 . 
       FIG. 2  is a timing diagram of signals applied to the flat panel display device according to an exemplary embodiment of the present invention. 
     According to a driving method during a lighting test or an aging process for the flat panel display device according to the exemplary embodiment of the present invention, the scan signals are sequentially applied to the plurality of scan lines S 1  to Sn so as to sequentially select pixels PB, PR and PG from the first, second and third pixel columns  101 ,  102  and  103  of the pixel portion  100 , and first and second control signals are synchronized with the scan signals and applied to the first and second control interconnections C 1  an C 2  of the lighting tester. 
     Now, voltages applied to the pixel columns  101 ,  102  and  103  from the lighting tester by the first and second control signals through the plurality of scan lines S 1  to Sn to which the scan lines are applied will be described with reference to  FIG. 2 . 
     First, when a first scan line S 1  is selected from the plurality of scan lines S 1  to Sn, which can be referred to as a first time period, the first transistor M 1  coupled between the first pixel column  101  and the first interconnection Vb, and the forth transistor M 4  coupled between the second pixel column  102  and the second interconnection Vr through which the second voltage for the second pixel PR is supplied, are turned on in response to a low-level first control signal applied through the first control interconnection C 1 . And, the third transistor M 3  coupled between the second pixel column  102  and the first interconnection Vb, and the second transistor M 2  coupled between the second pixel column  101  and the second interconnection Vr, are turned off in response to a high-level second control signal applied through the second control interconnection C 2 . 
     Accordingly, a first voltage is applied to a first pixel PB 11  of the first pixel column  101  electrically connected with the first scan line S 1 , and a second voltage is applied to a second pixel PR 13  of the second pixel column  102  electrically connected with the first scan line S 1 . 
     Since a third control signal applied through the third control interconnection C 3  is in a low level, the fifth transistor M 5  coupled between the third pixel column  103  and the third interconnection Vg is turned on, and a third voltage is applied to a third pixel PG 12  of the third pixel column  103  electrically connected with the first scan line S 1 . 
     Next, when a second scan line S 2  is selected from the plurality of scan lines S 1  to Sn, which can be referred to as a second time period, the first transistor M 1  coupled between the first pixel column  101  and the first interconnection Vb, and the forth transistor M 4  coupled between the second pixel column  102  and the second interconnection Vr through which a second voltage for the second pixel PR is supplied, are turned off in response to a high-level first control signal applied through the first control interconnection C 1 . And, the third transistor M 3  coupled between the second pixel column  102  and the first interconnection Vb, and the second transistor M 2  coupled between the first pixel column  101  and the second interconnection Vr, are turned on in response to a low-level second control signal applied through the second control interconnection C 2 . 
     Accordingly, a first voltage is applied to a second pixel PR 21  of the first pixel column  101  electrically connected with the second scan line S 2 , and a second voltage is applied to a first pixel PB 23  of the second pixel column  102  electrically connected with the second scan line S 2 . 
     Since a third control signal applied through the third control interconnection C 3  is in a low level, the fifth transistor M 5  coupled between the third pixel column  103  and the third interconnection Vg is turned on, and a third voltage is applied to the third pixel PG 22  of the third pixel column  103  electrically connected with the third scan line S 2 . 
     Here, when the scan signal is applied ahead of the first, second and third voltages to the respective pixels PB, PR and PG, the first, second and third voltages applied to the respective pixels PB, PR and PG are not sufficiently recorded, which may cause a brightness difference between the pixels PB, PR and PG. Thus, the first, second and third voltages have to be applied faster than the scan signals by a leading time t 1  and longer than the scan signal by a lagging time t 2  to the respective pixels PB, PR and PG in response to the first, second and third control signals. That is, the first, second and third voltages applied to the respective pixels PB, PR and PG of the first, second and third pixel columns  101 ,  102  and  103  have to have larger pulse widths than the scan signals applied by the plurality of scan lines S 1  to Sn. 
     Subsequently, when a third scan line S 3  is selected from the plurality of scan lines S 1  to Sn, which also can be referred to as the first time period, like when the first scan line S 1  is selected as described above, a low-level first control signal is applied through the first control interconnection C 1 , a high-level second control signal is applied through the second control interconnection C 2 , and a low-level third control signal is applied through the third control interconnection C 3 . Thus, the first transistor M 1  coupled between the first pixel column  101  and the first interconnection Vb, the fourth transistor M 4  coupled between the second pixel column  102  and the second interconnection Vr through which a second voltage for a second pixel PR is supplied, and the fifth transistor M 5  coupled between the third pixel column  103  and the third interconnection Vg are turned on. And, the third transistor M 3  disposed between the second pixel column  102  and the first interconnection Vb and the second transistor M 2  disposed between the first pixel column  101  and the second interconnection Vr are turned off. 
     Accordingly, a first voltage is applied to the first pixel line  101  electrically connected with the first scan line S 1 , a second voltage is applied to the second pixel column  102  electrically connected with the first scan line S 1 , and a third voltage is applied to the third pixel column  103 . 
     While the lighting test or aging process is performed on the pixel portion using the lighting tester in the exemplary embodiment of the present invention, if the lighting tester includes a lighting test power source and an aging power source, the lighting test may be performed by connecting a lighting test voltage source corresponding to each pixel to the first, second or third interconnection, and then the aging process may be performed by connecting an aging power source corresponding to each pixel to the first, second or third interconnection, and vice versa. 
     As a result, the flat panel display device according to the exemplary embodiment of the present invention has the first to fourth transistors controlled in response to the first and second control signals, which are disposed between the first and second interconnections and the first and second pixel columns of the lighting tester. Here, the first and second control signals are synchronized with the scan signals and inverted with respect to each other, such that the first or second interconnection to which a different voltage is supplied is connected with each of the first and second pixel columns having the first and second pixels arranged in reverse order to apply a different direct current therethrough. Thus, the lighting test or aging process can be performed for each pixel of each pixel column, and direct lighting test voltages or direct aging voltages can be applied to corresponding pixels, without adding equipment or modifying conventional equipment. 
     Consequently, a flat panel display device according to the present invention has first pixel column in which first pixels for displaying a first color and second pixels for displaying a second color are alternately arranged in a direction parallel to a plurality of data lines, and second pixel column in which first and second pixels are arranged in reverse order in a direction parallel to the plurality of data lines. The first and second columns are connected with first and second interconnections to which different voltages are supplied in response to first and second control signals of a lighting tester, both signals are synchronized with scan signals such that different direct voltages are applied through the first and second interconnections. Thus, the present invention can test the lighting of each pixel or sufficiently age each pixel of the pixel portion without adding equipment or modifying conventional equipment, and can prevent a brightness difference between pixels during the lighting test. 
     Although a few embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in this embodiment without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.