Patent Publication Number: US-9905587-B2

Title: Array substrate comprising a conductive contact formed on a surface of a pixel electrode exposed by an opening, manufacturing method thereof, and display panel

Description:
FIELD OF THE INVENTION 
     The present invention relates to the field of display technology, and in particular relates to an array substrate and a manufacturing method thereof, and a display panel. 
     BACKGROUND OF THE INVENTION 
     Due to the advantages of light weight, thin thickness, small size, low power consumption, low heat, etc., an LCD (Liquid Crystal Display) stands out from numerous different types of displays and has been widely applied to TVs, computers, tablet computers, mobile phones and other modern information appliances. 
     For thin-film transistor liquid crystal display panels, the characteristics of the thin-film transistors have significant influence on the display quality of the display panels, and many poor display events are all related to the abnormity of characteristics of the thin-film transistors. For TN (Twirsted Enmatic) display panels, the switching characteristics of each thin-film transistor can be tested easily. However, for the conventional ADS (Advanced Super Dimension Switch) array substrates as shown in  FIGS. 1A-1C , the switching characteristics of a thin-film transistor cannot be tested directly. As shown in  FIGS. 1A-1C , a conventional ADS array substrate comprises a substrate  1 ; a gate  2  formed on the substrate  1 ; a gate insulating layer  7  formed on the gate  2 ; an active layer  4  being corresponding to the gate  2  and formed on the gate insulating layer  7 ; a source-drain electrode  3  formed on the active layer  4 ; a pixel electrode  5  formed on the gate insulating layer  7  and electrically connected to the drain of the thin-film transistor; a passivation layer  8  covering the source-drain electrode  3  and the pixel electrode  5 ; and a common electrode  6  being corresponding to the pixel electrode  5  and formed on the passivation layer  8 . In the ADS array substrate, the pixel electrode  5  is located beneath the common electrode  6  and the passivation layer  8  (as shown in  FIG. 1B  and  FIG. 1C ), thus the switching characteristics of the thin-film transistor cannot be measured directly. As a result, it is unable to determine the impact of the characteristics of the thin-film transistor on the poor display events during failure analysis, greatly influencing the analysis for the poor display events of the display panel. 
     SUMMARY OF THE INVENTION 
     The technical problem to be solved by the present invention is that it is difficult to measure the switching characteristics of the thin-film transistor in the ADS array substrate. 
     To solve the technical problem mentioned above, the present invention provides an array substrate, comprising a plurality of pixel units, each of which comprising: a gate formed on a substrate; a gate insulating layer formed on the gate; an active layer being corresponding to the gate and formed on the gate insulating layer; a source and a drain respectively formed on the active layer; a pixel electrode formed on the gate insulating layer and electrically connected to the drain; a passivation layer covering the source, the drain and the pixel electrode; and a common electrode being corresponding to the pixel electrode and formed on the passivation layer, wherein an opening passing through the passivation layer is formed in the common electrode, so as to expose the pixel electrode below the passivation layer. 
     Preferably, the array substrate further comprises a conductive contact formed on a part of the pixel electrode exposed by the opening. 
     Further, the drain is formed on the pixel electrode. 
     The present invention further provides a display panel, comprising any one array substrate described above, wherein a black matrix inside the display panel shield the openings. 
     Further, the openings are formed in blue pixels of the display panel. 
     Further, the display panel comprises at least nine openings which are distributed uniformly. 
     The present invention further provides a manufacturing method of an array substrate, comprising the following steps: forming a gate on a substrate; forming a gate insulating layer on the gate; forming an active layer corresponding to the gate on the gate insulating layer; forming a pixel electrode on the gate insulating layer; forming a source and a drain on the active layer; depositing a passivation layer to cover the source, the drain and the pixel electrode; forming a common electrode corresponding to the pixel electrode on the passivation layer; and forming an opening passing through the passivation layer in the common electrode, so as to expose the pixel electrode below the passivation layer. 
     The method further comprises: forming a conductive contact on a part of the pixel electrode exposed by the opening. 
     Further, the conductive contact is formed in the same step as the source and the drain. 
     Further, the drain is formed on the pixel electrode. 
     With the solutions disclosed by the present invention, by using the existing manufacturing process with mask, an array substrate in which the characteristics of the thin-film transistor can be measured easily is manufactured, so that the accuracy of analysis for poor display events of the display panel is improved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The features and advantages of the present invention will be understood more clearly with reference to the accompanying drawings. The drawings are illustrative and should not be regarded as any limitation to the present invention. In the drawings: 
         FIG. 1A  is a plan view of an ADS array substrate in the prior art; 
         FIG. 1B  is a sectional view taken along line A-A′ in  FIG. 1A ; 
         FIG. 1C  is a sectional view taken along line B-B′ in  FIG. 1A ; 
         FIG. 2A  is a plan view of an array substrate according to an embodiment of the present invention; 
         FIG. 2B  is a sectional view taken along line C-C′ in  FIG. 2A ; 
         FIG. 3  is a test diagram of an array substrate according to an embodiment of the present invention; 
         FIG. 4  is a flowchart diagram of a method for manufacturing an array substrate according to the embodiment of the present invention; and 
         FIG. 5  shows an array substrate according to another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The embodiments of the present invention will be described in details as below in conjunction with the accompanying drawings. 
       FIG. 2A  is a plan view of an array substrate according to an embodiment of the present invention, and  FIG. 2B  is a sectional view taken along line C-C′ in  FIG. 2A . As the sectional view taken along line A-A′ in  FIG. 2A  is the same as  FIG. 1B , the sectional view taken along line A-A′ in  FIG. 2A  will not be shown repeatedly here. As shown in  FIG. 1B , similar to the array substrate in the prior art, the array substrate according to an embodiment of the present invention comprises a plurality of pixel units, each of which comprises: a substrate  1 ; a gate  2  formed on the substrate  1 ; a gate insulating layer  7  formed on the gate  2 ; an active layer  4  being corresponding to the gate  2  and formed on the gate insulating layer  7 ; a source-drain electrode  3  formed on the active layer  4 ; a pixel electrode  5  formed on the gate insulating layer  7  and electrically connected to the drain of the thin-film transistor; a passivation layer  8  covering the source-drain electrode  3  and the pixel electrode  5 ; and a common electrode  6  being corresponding to the pixel electrode  5  and formed on the passivation layer  8 . Different from the array substrate in the prior art, the array substrate according to an embodiment of the present invention further comprises an opening (as shown in  FIG. 2A ) formed in the common electrode  6 , the opening  9  passing through the passivation layer  8  to expose the pixel electrode  5  below the passivation layer  8 , and a conductive contact  10  is formed on the exposed part of the pixel electrode  5  for testing the thin-film transistor, as shown in  FIG. 2B . The conductive contact  10  may be made of the same material as the source and the drain. Therefore, the conductive contact  10  may be formed in the same step as the source-drain electrode  3 . 
     During the test of the characteristics of the thin-film transistor, a gate signal and a source signal need to be loaded; furthermore, a drain signal needs to be measured.  FIG. 3  is a test diagram of an array substrate according to the embodiment of the present invention. As shown in  FIG. 3 , a source signal may be easily loaded through a data line  12 . Therefore, the difficulty of test of the thin-film transistor is to load the gate signal and measure the drain signal. The gate line  11  of the array substrate may be connected to an external test pad  13 , to load the gate signal through the test pad  13 ; furthermore, the drain signal may be measured through the conductive contact  10 , so that signals of the thin-film transistor may be loaded and tested. 
       FIG. 5  shows an array substrate according to another embodiment of the present invention. As the pixel electrode  5  is conductive itself, conductive contact may not be formed on the exposed pixel electrode  5 . Instead, the drain signal may be measured directly through the exposed pixel electrode  5 . In this way, the test on the thin-film transistor may also be realized. 
     The embodiment of the present invention further provides a display panel comprising any one array substrate described above. Certainly, the display panel further comprises other known structures, for example, a color film, a black matrix and the like, which will not be described in details here. 
     In the display panel comprising the array substrate according to the embodiment of the present invention, in each pixel unit, an opening is formed within the pixel region to expose the pixel electrode  5 , thus the electric field within the opening area is changed. Therefore, it is required to shield the opening areas by a black matrix, so as to avoid abnormal display. In this way, the conductive contact  10  is located within the non-display region of the array substrate. In addition, in the display panel, as blue pixels have the lowest transmittance, the openings are preferably provided in the blue pixels in order to reduce the influence on the transmittance. 
     In order not to affect the overall transmittance of the display panel, the openings may be uniformly distributed on the display panel. In order to make the characteristics of the thin-film transistor to be tested regionally representative, preferably, no less than nine openings are distributed evenly. On the premise that the transmittance is not significantly influenced, openings may be provided as much as possible. 
       FIG. 4  is a flowchart diagram of a method for manufacturing the array substrate according to the embodiment of the present invention. Still referring to  FIG. 1B , FIG.  2 A and  FIG. 2B , as shown in  FIG. 4 , the manufacturing method comprises steps S 1 -S 9 : S 1 : forming a gate  2  on a substrate  1 ; S 2 : forming a gate insulating layer  7  to cover the substrate  1  and the gate  2 ; S 3 : forming an active layer  4  corresponding to the gate  2  on the gate insulating layer  7 ; S 4 : forming a pixel electrode  5  on the gate insulating layer  7 ; S 5 : depositing a source-drain metal layer; S 6 : patterning the source-drain metal layer to form a source, a drain and a conductive contact  10 , wherein the source and the drain are located on the active layer  4 , the drain is located on and in electric contact with the pixel electrode  5 , and, the conductive contact  10  is located on and in electric contact with the pixel electrode  5  and is located within an opening to be formed; S 7 : depositing a passivation layer  8  to cover the source, the drain, the pixel electrode  5  and the conductive contact  10 ; S 8 : forming a common electrode  6  on the passivation layer  8 ; and S 9 : forming the opening  9  passing through the passivation layer  8  in the common electrode  6 , so as to expose the conductive contact  10 . 
     With the solutions disclosed by the present invention, by using the existing manufacturing process with mask, an array substrate in which the characteristics of the thin-film transistor can be measured easily is manufactured, so that the accuracy of analysis for poor display events of the display panel is improved. 
     Although the embodiments of the present invention have been described with reference to the accompanying drawings, a person skilled in the art may make various modifications and variations without departing from the spirit and scope of the present invention. These modifications and variations shall be within the scope defined by the appended claims.