Patent Publication Number: US-9429785-B2

Title: In-cell touch type liquid crystal display device

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 14/584,020, filed on Dec. 29, 2014, which claims priority from Korean Patent Application No. 10-2014-0111791, filed on Aug. 26, 2014, all of which are hereby incorporated by reference for all purposes as if fully set forth herein. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a liquid crystal display device (LCD), and more particularly, to an in-cell touch type LCD. 
     2. Discussion of the Related Art 
     Recently, LCDs have been spotlighted as next generation high-tech display devices of low power consumption, good portability, high added value and the like. 
     Among the LCDs, active matrix type LCDs are widely used, which includes a thin film transistor (TFT) in each pixel. 
     The LCD is applied to various appliances such as TV, projector, mobile phone and PDA, and the appliances have a touch function to touch a screen and conduct an operation. 
     An LCD having a touch function embedded therein is referred to as an in-cell touch type LCD. 
     The in-cell touch type LCD includes gate and data lines, and additionally, touch blocks to sense a touch and touch lines connected to the touch blocks. 
     In the in-cell touch type LCD, a common electrode is supplied with a common voltage for a display period to display an image. The common electrode functions as a touch electrode to sense a touch for a non-display period not to display an image. 
     Accordingly, when a user touch a touch region, for example, using a user&#39;s finger, a touch capacitance is produced between common electrodes which are separately formed at respective touch blocks. A touch position is detected by comparing the touch capacitance by the user&#39;s touch with a reference capacitance, and an operation according to the touch position is conducted. 
     In this regard, by comparing the touch capacitance with the reference capacitance, a coordinate where the user&#39;s touch happens is recognized, and then an operation corresponding to the coordinate is conducted. 
     Accordingly, a touch line, which transmits change of capacitance of a common electrode formed at each touch block to a sensing circuit portion that is located at a non-display region or printed circuit board, is required. Since the touch line is connected to the common electrode, the touch line cannot be formed at the same layer as the common electrode. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention is directed to an in-cell touch type liquid crystal display device (LCD) that substantially obviates one or more of the problems due to limitations and disadvantages of the related art. 
     An object of the present invention is to provide an in-cell touch type LCD that can compensate for a load difference between a gate line at an inner region of a touch block and a gate line at a boundary region of a touch block and improve display quality. 
     Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. These and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
     To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, an in-cell touch type liquid crystal display device includes gate and data lines crossing each other at a boundary of a pixel region on a substrate which includes a plurality of touch block each including a plurality of pixel regions; a thin film transistor in each pixel region and connected to the gate and data lines; a pixel electrode in the pixel region connected to the thin film transistor; a first passivation layer on the pixel electrode; a touch line and a dummy touch line along a direction between neighboring pixel electrodes on the first passivation layer; a second passivation layer on the touch line and the dummy touch line; and common electrodes separated from one another in respective touch blocks, and each including first openings corresponding to each pixel region and a second opening corresponding to the touch line, wherein a connection pattern extending over the gate line from a side of the touch line at an inner region of the touch block is connected to the common electrode through a touch contact hole, and wherein an open portion is between the touch line and the dummy touch line. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
    
    
     
       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 view illustrating a structure of touch blocks of an in-cell touch type LCD according to a first embodiment of the present invention; 
         FIG. 2  is a view illustrating an in-cell touch type LCD according to a first embodiment of the present invention; 
         FIGS. 3A and 3B  are views illustrating an inner region and a boundary region of a touch block of an in-cell touch type LCD according to a first embodiment of the present invention, respectively; 
         FIGS. 4 and 5  are views illustrating an inner region and a boundary region of a touch block of an in-cell touch type LCD according to a first embodiment of the present invention, respectively; 
         FIG. 6  is a graph illustrating a brightness difference between a pixel region at an inner region of a touch block and a pixel region at a boundary region of a touch block according to a first embodiment of the present invention; 
         FIG. 7  is a view illustrating an in-cell touch type LCD according to a first embodiment of the present invention; 
         FIG. 8  is a view illustrating a structure of touch blocks of an in-cell touch type LCD according to a second embodiment of the present invention; 
         FIG. 9  is a view illustrating an inner region of a touch block of an in-cell touch type LCD according to a second embodiment of the present invention; and 
         FIG. 10  is a view illustrating a boundary region of a touch block of an in-cell touch type LCD according to a second embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS 
     Reference will now be made in detail to exemplary embodiments, examples of which are illustrated in the accompanying drawings. The same reference numbers may be used throughout the drawings to refer to the same or like parts. 
     First Embodiment 
       FIG. 1  is a view illustrating a structure of touch blocks of an in-cell touch type LCD according to a first embodiment of the present invention,  FIG. 2  is a view illustrating an in-cell touch type LCD according to a first embodiment of the present invention, and  FIGS. 3A and 3B  are views illustrating an inner region and a boundary region of a touch block of an in-cell touch type LCD according to a first embodiment of the present invention, respectively. For the purpose of explanation, touch lines and common electrodes are omitted in  FIG. 2 , and touch lines are omitted in  FIGS. 3A and 3B . 
     Referring to  FIGS. 1 to 3B , the in-cell touch type LCD includes a display region including a plurality of pixel regions and a non-display region surrounding a display region. 
     A plurality of touch blocks TB are defined in the in-cell touch type LCD. The plurality of touch blocks TB each have a group of pixel regions neighboring to one another in a row direction and a column direction. 
     Gate lines  14  and data lines  16  are formed on a substrate and cross each other to define pixel regions. 
     Each pixel region includes a thin film transistor T connected to the corresponding gate and data lines  14  and  16 , and a pixel electrode  18  connected to a drain electrode  17  of the thin film transistor T. 
     A touch line  190   a  and a dummy touch line  190   b  is formed at a boundary of the pixel region between the pixel electrodes  18 . A passivation layer (not shown) is formed on the touch line  190   a , the dummy touch line  190   b  and the pixel electrode  18 . 
     Common electrodes  170  are formed on the passivation layer and in respective touch blocks TB, and are separated from one another. The common electrode  170  includes first openings  130  corresponding to each pixel region, and a second opening  135  corresponding to the touch line  190   a . The second opening  135  has a shape similar to the first opening  130 . 
     The touch line  190   a  is below the common electrodes  170 . The touch line  190   a  is connected to the common electrode  170  of the corresponding touch block TB through a touch contact hole TCH. The touch line  190   a  is not connected to common electrodes  170  of touch blocks TB other than the corresponding touch block TB connected thereto. The touch line  190   a  transmits a touch signal i.e., change of capacitance between neighboring common electrodes  170 . 
     The dummy touch line  190   b  is formed below the common electrodes  170  and is not connected to any common electrodes  170 . In other words, the dummy touch line  190   b  does not transmit a touch signal. 
     In this regard, the touch lines  190   a  connected to the common electrodes  170  of the touch blocks TB are arranged substantially non-uniformly on an array substrate, thus capacitances between the common electrodes  170  and the touch lines  190   a  become different, and thus display quality is degraded. To prevent this, the dummy touch lines  190   b  are formed. 
     The touch line  190   a  and the dummy touch line  190   b  are not connected to each other, and an open portion OPEN between the touch line  190   a  and  190   b  is formed at a boundary portion of the touch block TB. 
     The common electrode  170  includes the first openings  130  in each pixel region, and the second opening  135  corresponding to the touch line  190   a  and the dummy touch line  190   b . Further, the common electrode  170  includes a third opening  150  corresponding to the thin film transistor T, and a fourth opening  155  corresponding to the gate line  14 . 
     The common electrode  170  formed at an inner region TIA of the touch block TB extends over a region “A” corresponding to the gate line  14  between the pixel electrodes  18  of neighboring pixel regions. Accordingly, portions of the common electrode  170  corresponding to the pixel regions in the touch block TB are connected to one another through the regions “A”. 
     Accordingly, a portion of the common electrode  170  corresponding to the pixel region in the inner region TIA of the touch block TB has an area greater than a portion of the common electrode  170  corresponding to the pixel region at a boundary region TBA of the touch block TB. 
       FIGS. 4 and 5  are views illustrating an inner region and a boundary region of a touch block of an in-cell touch type LCD according to a first embodiment of the present invention, respectively. 
     Referring to  FIGS. 4 and 5 , in the in-cell touch type LCD, a connection pattern  190   c  extends from the touch line  190   a  at the inner region TIA of the corresponding touch block TB, and is connected to the common electrode  170  through the touch contact hole TCH. The connection pattern  190   c  may be located corresponding to the gate line  14 . The open portion OPEN is formed between the touch line  190   a  and the dummy touch line  190   b.    
     A first passivation layer is formed on the pixel electrode  18 . The touch line  190   a  and the dummy touch line  190   b  are formed on the first passivation layer at the boundary of the pixel region. A second passivation layer is formed on the touch line  190   a  and the dummy touch line  190   b . The common electrode  170  is formed on the second passivation layer. 
     The connection pattern  190   c  extending from one side of the touch line  190   a  is connected to the common electrode  170 , and the touch line  190   a  transmits a touch signal to a sensing circuit. 
     It is preferred, but not limited, that the touch line  190   a  and the dummy touch line  190   b  are formed of a low resistance metal material such as aluminum (Al) or copper (Cu) to prevent delay of a touch signal. 
     The touch line  190   a  and the dummy touch line  190   b  are formed at the boundary of the pixel region between the pixel electrodes  18 . The touch line  190   a  and the dummy touch line  190   b  are not connected to a region between neighboring touch blocks TB. The open portion OPEN between the touch line  190   a  and the dummy touch line  190   b  is formed over the gate line  14  at the boundary portion TBA of the touch block TB. 
       FIG. 6  is a graph illustrating a brightness difference between a pixel region at an inner region of a touch block and a pixel region at a boundary region of a touch block according to a first embodiment of the present invention. 
     Referring to  FIGS. 4 and 5 , the common electrode  170  corresponding to the pixel region at the inner region TIA of the touch block TB has an additional area of the region “A”, compared with the common electrode  170  corresponding to the pixel region at the boundary region TBA of the touch block TB. 
     Further, at the inner region TIA of the touch block TB, the connection pattern  190   c  extending over the gate line  14  (i.e., “Gate a” in  FIG. 6 ) from the touch line  190   a  is connected to the common electrode  170 . However, at the boundary region TBA of the touch block TB, the open portion TBA is formed, and the connection pattern  190   c  and the common electrode  170  are not formed. 
     Accordingly, at the inner region TIA of the touch block TB, due to a capacitance produced between the gate line “Gate a”, and the connection pattern  190   c  and the common electrode at the region A, a load of the gate line “Gate a” at the inner region TIA of the touch block TB increases. 
     However, at the boundary region TBA of the touch block TB, the connection pattern  190   c  and the common electrode  170  are not formed over the gate line  14  (i.e., “Gate b” in  FIG. 6 ), thus no capacitance therebetween is produced, and thus a load of the gate line “Gate b” at the boundary region TBA of the touch block TB is less than that of the gate line “Gate a” at the inner region TIA of the touch block TB. 
     Accordingly, referring to  FIG. 6 , since an output of a gate signal applied to the gate line “Gate b” of a less load increases, a charging time of a data voltage of a pixel electrode of the pixel region at the boundary region TBA increases, and thus this pixel region is relatively high charged with a data voltage Vb. 
     However, since an output of a gate signal applied to the gate line “Gate b” of a greater load decreases, a charging time of a data voltage of a pixel electrode of the pixel region at the inner region TIA decreases, and thus this pixel region is relatively low charged with a data voltage Va. 
     Accordingly, the pixel region at the boundary region TBA of the touch block TB is seen brighter than the pixel region at the inner region TIA of the touch block, and thus display quality is degraded. 
     Second Embodiment 
       FIG. 7  is a view illustrating an in-cell touch type LCD according to a first embodiment of the present invention, and  FIG. 8  is a view illustrating a structure of touch blocks of an in-cell touch type LCD according to a second embodiment of the present invention. For the purpose of explanation, touch lines and common electrodes are omitted in  FIG. 7 . Further, explanations of parts similar to parts of the first embodiment may be omitted. 
     Referring to  FIGS. 7 and 8 , the in-cell touch type LCD includes a display region including a plurality of pixel regions and a non-display region surrounding a display region. 
     A plurality of touch blocks TB are defined in the in-cell touch type LCD. The plurality of touch blocks TB each have a group of pixel regions neighboring to one another in a row direction and a column direction. 
     Gate lines  114  and data lines  116  are formed on a substrate and cross each other to define pixel regions. 
     Each pixel region includes a thin film transistor T connected to the corresponding gate and data lines  114  and  116 , and a pixel electrode  118  connected to a drain electrode  117  of the thin film transistor T. 
     A touch line  290   a  and a dummy touch line  290   b  is formed at a boundary of the pixel region between the pixel electrodes  118 . A passivation layer (not shown) is formed on the touch line  290   a , the dummy touch line  290   b  and the pixel electrode  118 . 
     Common electrodes  270  are formed on the passivation layer and in respective touch blocks TB, and are separated from one another. 
     The touch line  290   a  is below the common electrodes  270 . The touch line  290   a  is connected to the common electrode  270  of the corresponding touch block TB through a touch contact hole TCH. The touch line  290   a  is not connected to common electrodes  270  of touch blocks TB other than the corresponding touch block TB connected thereto. The touch line  290   a  transmits a touch signal i.e., change of capacitance between neighboring common electrodes  270 . 
     The dummy touch line  290   b  is formed below the common electrodes  270  and is not connected to any common electrodes  270 . In other words, the dummy touch line  190   b  does not transmit a touch signal. 
     In this regard, the touch lines  290   a  connected to the common electrodes  270  of the touch blocks TB are arranged substantially non-uniformly on an array substrate, thus capacitances between the common electrodes  270  and the touch lines  290   a  become different, and thus display quality is degraded. To prevent this, the dummy touch lines  290   b  are formed. 
     The touch line  290   a  and the dummy touch line  290   b  are not connected to each other with an open portion OPEN therebetween. The open portion OPEN is formed at a region other than a region of the gate line  114 . In other words, the open portion OPEN is formed at the inner region TIA of the touch block TB. 
     Accordingly, a compensation pattern  290   d  extending from the touch line  290   a  and the dummy touch line  290   b  is formed corresponding to the gate line  114  at a boundary region of the touch block TB. The compensation pattern  290   d  are preferably formed to have the same shape as a connection pattern extending from the touch line  290   a  at an inner region of the touch block TB. 
       FIG. 9  is a view illustrating an inner region of a touch block of an in-cell touch type LCD according to a second embodiment of the present invention, and  FIG. 10  is a view illustrating a boundary region of a touch block of an in-cell touch type LCD according to a second embodiment of the present invention. 
     Referring to  FIGS. 9 and 10 , in the in-cell touch type LCD, a connection pattern  290   c  extends from the touch line  290   a  at the inner region TIA of the corresponding touch block TB, and is connected to the common electrode  270  through the touch contact hole TCH. The connection pattern  290   c  may be located corresponding to the gate line  114 . The open portion OPEN is formed between the touch line  290   a  and the dummy touch line  290   b.    
     The touch line  290   a  is formed at the boundary of the pixel region and extends along a direction. 
     The common electrode  270  includes first openings  230  in each pixel region, and a second opening  235  corresponding to the touch line  290   a  and the dummy touch line  290   b . Further, the common electrode  270  includes a third opening  250  corresponding to the thin film transistor T, and a fourth opening  255  corresponding to the gate line  114 . The common electrodes  230  are separated by the fourth opening  255 . 
     The common electrode  270  includes a third opening  250  corresponding to the thin film transistor T, and extends over the gate line  114  at the inner region TIA of the touch block TB. 
     The connection pattern  290   c  extending from one side of the touch line  290   a  is connected to the common electrode  270  through the touch contact hole TCH, and the touch line  290   a  transmits a touch signal to a sensing circuit. 
     It is preferred, but not limited, that the touch line  290   a  and the dummy touch line  290   b  are formed of a low resistance metal material such as aluminum (Al) or copper (Cu) to prevent delay of a touch signal. 
     A first passivation layer is formed on the pixel electrode  118 . The touch line  290   a  and the dummy touch line  290   b  are formed on the first passivation layer at the boundary of the pixel region. A second passivation layer is formed on the touch line  290   a  and the dummy touch line  290   b . The common electrode  270  is formed on the second passivation layer. 
     The compensation pattern  290   d  extends from one side of the touch line  290   a  and the dummy touch line  290   b  at the boundary region TBA of the touch block TB and corresponds to the gate line  114 . 
     A separate distance between the common electrodes  270  at the boundary region TBA of the touch block TB may be reduced to about 2 um to prevent short-circuit between the common electrodes  270 . 
     Accordingly, an area of the common electrode  270  over the gate line  114  at the boundary region TBA of the touch block TB may be almost equal to an area of the common electrode  270  over the gate line  114  at the inner region TIA of the touch block TB. 
     Accordingly, a load of the gate line  114  at the boundary region TBA of the touch block TB is equal to a load of the gate line  114  at the inner region TIA of the touch block TB, thus output waveforms of the gate lines  114  become equal and charging times of data voltages of pixel electrodes  118  becomes equal, and thus brightness of the pixel region at the inner region TIA of the touch block TB and brightness of the pixel region at the boundary region TBA of the touch block can become equal. Therefore, degradation of display quality can be prevented. 
     Further, the open portion OPEN between the touch line  290   a  and the dummy touch line  290   b  is formed outside a region of the gate line  114  at the boundary region TBA of the touch block TB. 
     The open portion OPEN is preferably formed below the gate line at the boundary region TBA of the touch block TB and between the pixel regions. 
     The open portion OPEN is formed outside the gate line at the boundary region TBA, and thus the compensation pattern  290   d  extending from the dummy touch line  290   a  can be formed over the gate line at the boundary region TBA. 
     In accordance with example embodiments, an in-cell touch type LCD may be provided that compensates for a load difference between a gate line at an inner region of a touch block and a gate line at a boundary region of a touch block and improves display quality. As described above, in the in-cell touch type LCD, the open portion between the touch line and the dummy touch line is formed outside the gate line at the boundary region of the touch block, and the compensation pattern, which has the same shape as the connection pattern at the inner region of the touch block is formed over the gate line at the boundary region of the touch block. Therefore, brightness of the pixel regions at the inner region of the touch block can be equal to brightness of the pixel region at the boundary region of the touch block, and thus display quality can be improved. 
     It will be apparent to those skilled in the art that various modifications and variation can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.