Patent Publication Number: US-2023152646-A1

Title: Pixel unit, array substrate, and display panel

Description:
FIELD OF INVENTION 
     The present disclosure relates to a display technology field, particularly to a pixel unit technology field, specifically to a pixel unit, an array substrate, and a display panel. 
     BACKGROUND OF INVENTION 
     As market requires liquid crystal displays with wider and wider viewing angles, developers have developed 8-domain designs. In order to ensure penetration rates of panels, they have successively developed three transistors and more than three transistors (3T&amp;3T+) pixel structure designs. However, a side effect of the 3T&amp;3T+ is worsened display at junctions of an exposure area, as the area will generate band-shaped, uneven spots (Lens-Mura). 
     An exposure process is required during a formation of thin film transistors. However, exposure will be performed in sections, due to a limitation of sizes of exposure machines. For example, a G8.5 NIKON exposure machine is spliced and connected by 11 lens. Based on this, light fluxes at junctions and non-junctions are different, which lead to regular difference in critical dimension (CD) after lithography and coincidence accuracy (referred to as OL) between patterns during lithography of shared thin film transistors in the 3T&amp;3T+, which in turn lead to an occurrence of Lens-Mura related to lens match. 
     The 3T&amp;3T+ introduces a third thin film transistor (TFT), a sub-thin film transistor (sub-TFT) connects to a transparent common electrode line (C_ITO) in the 3T structure or a share bar (shared metal wire) in the 3T+ structure through the 3rd-TFT (shared thin film transistor), and a brightness of a sub-pixel is adjusted by controlling a signal of the C_ITO/share bar, so as to improve panel viewing angles. The 3rd-TFT is different from the main thin film transistor (main-TFT) &amp; sub-TFT in position and orientations, and thus it cannot be adjusted equivalently by adjusting lens. For example, when DCD of channel length (CL) of the main-TFT/sub-TFT is 0, DCD of CL of the 3rd-TFT is 0.2 um, wherein DCD is the CD difference between the lens area and the lens junction area. The existence of DCD leads to different partial voltages of 3rd-TFTs in the lens area and the lens junction area, and the occurrence of Lens-Mura. 
     However, in traditional technical solutions, both the 3rd-TFT in the lens area and the 3rd-TFT in the lens junction area are connected to the same C_ITO/share bar signal, resulting in independent adjustment of the 3rd-TFT in the lens area or the 3rd-TFT in the lens junction area, and thus leads to the deterioration of the Lens-Mura. 
     SUMMARY OF INVENTION 
     The present disclosure provides a pixel unit, which solves the deterioration problem of Lens-Mura caused by different partial voltages of the shared thin film transistors in the lens areas and the lens junction areas. 
     In the first aspect, the present disclosure provides a pixel unit, wherein the pixel unit includes main pixel areas and sub-pixel areas, and the sub-pixel areas are provided with shared thin film transistors to pull down the voltages of sub-pixel electrodes; gates of the shared thin film transistors are connected to scan lines corresponding to the pixel unit, sources of the shared thin film transistors are connected to the sub-pixel electrodes, and drains of the shared thin film transistors are connected to common signal lines; the shared thin film transistors have lens areas and lens splicing areas alternately formed corresponding to an exposure equipment during the manufacturing process, wherein the common signal lines connected to the shared thin film transistors located in the lens areas are configured as first common signal lines for receiving first common voltage signals, and common signal lines connected to the shared thin film transistors located in the lens splicing areas are configured as second common signal lines for receiving second common voltage signals. 
     On the basis of the first aspect, in the first embodiment of the first aspect, the main pixel areas are provided with main thin film transistors, and the sub-pixel areas are provided with sub-thin film transistors; data lines corresponding to the pixel unit are connected with drains of the main thin film transistors and the sub-thin film transistors; the scan lines are connected to gates of the main thin film transistors, gates of the sub-thin film transistors, and the gates of the shared thin film transistors; sources of the main thin film transistors are connected to main pixel electrodes arranged in the main pixel areas; and sources of the sub-thin film transistors are connected to the sub-pixel electrodes and the sources of the shared thin film transistors. 
     On the basis of the first aspect, in the second embodiment of the first aspect, the first common signal lines and the second common signal lines are both transparent metal wires and are located in different film layers. 
     On the basis of the first aspect, in the third embodiment of the first aspect, voltages of the first common voltage signals are different from voltages of the second common voltage signals. 
     On the basis of the first aspect, in the fourth embodiment of the first aspect, each second common signal line is connected to the drains of the shared thin film transistors in a corresponding column, and the shared thin film transistors in the corresponding column are located in the lens splicing areas. 
     On the basis of the first aspect, in the fifth embodiment of the first aspect, each first common signal line is connected to the drains of the shared thin film transistors in a corresponding column, and the shared thin film transistors in the corresponding column are located in the lens areas. 
     In the second aspect, the present disclosure provides an array substrate, which comprises a plurality of pixel units according to any one of the above embodiments, and the plurality of pixel units are distributed in array arrangement on the array substrate. 
     In the third aspect, the present disclosure provides a display panel, which comprises the pixel unit and the color filter substrate of the first embodiment of the first aspect, and a liquid crystal layer between the pixel unit and the color filter substrate. 
     On the basis of the third aspect, in the first embodiment of the third aspect, a transparent electrode layer is formed on the color filter substrate; a main storage capacitor is formed between the main pixel electrode and the transparent electrode layer; and a sub-storage capacitor is formed between the sub-pixel electrode and the transparent electrode layer. 
     On the basis of the first embodiment of the third aspect, in the second embodiment of the third aspect, the main storage capacitor and the sub-storage capacitor have the same capacitance. 
     In the pixel unit provided in the present disclosure, the shared thin film transistors located in the lens area and the lens splicing area are respectively connected to the first common signal line and the second common signal line, and respectively receive the first common voltage signal and the second common voltage signal. The partial voltages of the shared thin film transistors in the lens area and the lens splicing area can be independently adjusted, and thus the Lens-Mura deterioration in the lens splicing area can be relieved. The array substrate provided in the present disclosure includes the pixel units and can also relieve the Lens-Mura occurring in the lens splicing area. The display panel provided by the present disclosures includes the pixel units and can also relieve the Lens-Mura occurring in the lens splicing area. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG.  1    is a schematic diagram of curves of channel length differences of thin film transistors in a pixel unit disclosed in the embodiments of the present disclosure. 
         FIG.  2    is a schematic structural diagram of common signal lines in conventional technical solutions. 
         FIG.  3    is a schematic structural diagram of a pixel unit disclosed in the embodiments of the present disclosure. 
         FIG.  4    is a schematic structural diagram of a first common signal line and a second common signal line disclosed in the embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     In order to make the purposes, technical solutions and effects of the present disclosure more clear, the present disclosure will be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present disclosure, and are not used to limit. 
     In order to better understand the present disclosure, channel length differences between main thin film transistors, sub-thin film transistors, and shared thin film transistors in lens areas  1  and a lens splicing area  2  are described with reference to  FIG.  1   , wherein M7 and M8 represent the lens area  1 , and M7 M8 represents the lens splicing area  2 . The channel length change curve S 1  of the main thin film transistors and the channel length change curve S 2  of the sub-thin film transistors are smooth, however, the channel length change curve S 3  of the shared thin film transistors appears to have a steep rise and fall in the lens splicing area  2 , and the difference in channel length exceeds 0.2 µm, which results in significant inconsistency in the partial voltages of the shared thin film transistors in the lens areas  1  and the lens splicing area  2 , thereby leading to deterioration of the Lens-Mura of the lens splicing area  2 . 
     As shown in  FIG.  2   , in the traditional technical solutions, common signal lines  3  connected to the shared thin film transistors of the lens areas  1  and the lens splicing areas  2  are connected together, and thus the partial voltages of the shared thin film transistors in the lens splicing areas  2  cannot be adjusted and improved, therefore the Lens-Mura of the lens splicing areas  2  exists till now. 
     Based on the above circumstances, in the present disclosure, the shared thin film transistors located in the lens areas  1  and the lens splicing areas  2  are connected to first common signal lines  31  and second common signal lines  32  respectively, and receive first common voltage signals and second common voltage signals respectively. The partial voltages of the shared thin film transistors in the lens areas  1  and the lens splicing areas  2  can be independently adjusted, thereby reducing the deterioration of the Lens-Mura in the lens splicing areas  2 . 
     As shown in  FIGS.  3  and  4   , the present embodiment provides a pixel unit. The pixel unit includes main pixel areas and sub-pixel areas. The sub-pixel areas are provided with shared thin film transistors  6  to pull down the voltages of sub-pixel electrodes. Gates  63  of the shared thin film transistors  6  are connected to scan lines  8  corresponding to the pixel unit, sources  62  of the shared thin film transistors  6  are connected to the sub-pixel electrodes, and drains  61  of the shared thin film transistors  6  are connected to common signal lines  3 . The shared thin film transistors  6  include the lens areas  1  and the lens splicing areas  2  alternately connected corresponding to an exposure equipment used in the manufacturing process. The common signal lines  3  connected to the shared thin film transistors  6  located in the lens areas  1  are configured as first common signal lines  31  for receiving first common voltage signals; the common signal lines  3  connected to the shared thin film transistors  6  in the lens splicing areas  2  are configured as a second common signal lines  32  for receiving second common voltage signals. 
     It should be noted that the sources  62  and the drains  61  of the shared thin film transistors  6  can be used interchangeably, and are not limited to the connection method in the present embodiment. The shared thin film transistors  6  can be, but not limited to, N-channel thin film transistors, and also can be P-channel thin film transistors. It can be expected that in the design process of the display panel, according to the size and number of lens used by the exposure machine, the lens areas  1  and the lens splicing areas  2  can be pre-calibrated through conversion, so as to distinguish the first common signal lines  31  and the first common signal lines  32  and to receive the first common voltage signals and the second common voltage signals respectively. On this basis, the shared thin film transistors  6  of the lens areas  1  and the lens splicing areas  2  can be adjusted separately, and the difference in partial voltages of the shared thin film transistors  6  in the lens splicing areas  2  can be eliminated and the Lens-Mura occurring in the lens splicing areas  2  can be relieved. 
     As shown in  FIG.  4   , in one of the embodiments, the main pixel areas are provided with main thin film transistors  4 , and the sub-pixel areas are provided with sub-thin film transistors  5 . Data lines  7  corresponding to the pixel unit are connected to drains  41  of the main thin film transistors  4  and drains  51  of the sub-thin film transistors  5 , and the scan lines  8  are connected to gates  43  of the main thin film transistors  4 , gates  53  of the sub-thin film transistors  5 , and gates  63  of the shared thin film transistors  6 . Sources  42  of the main thin film transistors  4  are connected to main pixel electrodes arranged in the main pixel area, and sources  52  of the sub-thin film transistors  5  are connected to the sub-pixel electrodes and the sources  62  of the shared thin film transistors  6 . 
     It should be noted that when the main thin film transistors  4  and the sub-thin film transistors  5  are N-channel thin film transistors, the sources and drains can be used interchangeably, and are not limited to the connection method in the embodiment. 
     In one of the embodiments, the first common signal lines  31  and the second common signal lines  32  are both transparent metal wires, and are located in different film layers. 
     It should be noted that the first common signal lines  31  and the first common signal lines  32  may be, but not limited to, located in different layers, and can be located in different layers of the same film layer or in the same layer of the same film layer. The first common signal lines  31  and the first common signal lines  32  are not crosswise with each other to avoid crosstalk. 
     In one of the embodiments, voltages of the first common voltage signals are different from voltages of the second common voltage signals. 
     It should be noted that, the second common voltage signals are used to adjust difference in the partial voltages of the shared thin film transistors  6  in the lens splicing areas  2 , and the second common voltage signals can be adjusted according to the channel length difference of the shared thin film transistors  6  in the lens splicing areas  2  until the Lens-Mura occurring in the lens splicing areas  2  is effectively eliminated. 
     In one of the embodiments, each second common signal line  32  is connected to the drains  61  of the shared thin film transistors  6  in a corresponding column, and the shared thin film transistors  6  in the corresponding column are located in the lens splicing areas  2 . 
     In one of the embodiments, each first common signal line  31  is connected to the drains  61  of the shared thin film transistors  6  in a corresponding column, and the shared thin film transistors  6  in the corresponding column are located in the lens areas  1 . 
     In one of the embodiments, the present disclosure provides an array substrate, which includes a plurality of pixel units disclosed in any one of the above embodiments, and the plurality of pixel units are distributed in array arrangement on the array substrate. 
     In one of the embodiments, the present disclosure provides a display panel, which includes the pixel unit and the color filter substrate disclosed in the first embodiment of the first aspect, and a liquid crystal layer between the pixel unit and the color filter substrate. 
     In one of the embodiments, a transparent electrode layer is formed on the color filter substrate; main storage capacitors are formed between the main pixel electrodes and the transparent electrode layer; and sub-storage capacitors are formed between the sub-pixel electrodes and the transparent electrode layer. 
     In one of the embodiments, the main storage capacitors and the sub-storage capacitors have the same capacitance. 
     It should be noted that the present embodiment is beneficial to the uniform display of the main pixel areas and the sub-pixel areas. 
     It can be understood that, for those of ordinary skill in the art, equivalent replacements or changes can be made according to the technical solutions and inventive concepts of the present disclosure, and all such changes or replacements should fall within the protection scope of the claims appended to the present disclosure.