Abstract:
Display devices for displaying images are provided. A representative display device incorporates a display panel that includes a display pixel and a non-display pixel. The display pixel includes at least one switching thin-film transistor and the non-display pixel includes dummy thin-film transistors. A number of the dummy thin-film transistors exceeds a number of the switching thin-film transistors.

Description:
BACKGROUND 
     The disclosure relates to image display technologies.  FIG. 1  is a schematic diagram of a display panel. The display panel  1  is formed by a deposition step, several photolithography steps, and several etching steps, among others. In any of the aforementioned processing steps, electrostatic charge may accumulate in the display panel. Since electrostatic charge tends to accumulate at the ends of a long metal line, a non-display area  14  is usually required around a display area  12  for reducing the potential of electrostatic discharging damage. 
       FIG. 2  is a schematic diagram of a portion or block  16  of the display panel  1 . Electrostatic charge can be relieved by thin-film transistors (TFTs) in non-display area  14 . Taking a long metal line  20  as an example, electrostatic charge is easily accumulated in the end of metal line  20  and then voltage potential decreases from the end to the middle portion of the metal line  20 . As such, a dielectric breakdown event will occur in gates of TFTs  141 ˜ 143  when electrostatic charge accumulated in the left end of metal line  20  reaches a threshold value. Therefore, electrostatic charge can be relieved by the dielectric breakdown event. 
     Since the dielectric breakdown event is non-recoverable, TFTs  141 ˜ 143  are easily damaged by electrostatic charge. Electrostatic charge will easily damage TFTs in display area  12  as the accumulated electrostatic charge is larger than that TFTs  141 ˜ 143  can relieve. Therefore, defects may easily occur in display area  12 . Additionally, TFTs  141 ˜ 143  are incrementally damaged more easily as the amount of electrostatic charge increases during manufacture. 
     SUMMARY 
     Display devices for displaying images are provided. An embodiment of such a display device comprises a display panel that comprises display pixels and non-display pixels. Each display pixel comprises at least one switching thin-film transistor. Each non-display pixel comprises a plurality of dummy thin-film transistors. The number of the dummy thin-film transistors of a first non-display pixel among the non-display pixels exceeds the number of the switching thin-film transistor of a first display pixel among the display pixels. 
     Another embodiment of a display device for displaying images comprises a display panel comprising a display pixel and a non-display pixel. The display pixel comprises at least one switching thin-film transistor and the non-display pixel comprises dummy thin-film transistors. A number of the dummy thin-film transistors exceeds a number of the switching thin-film transistors. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       The invention can be more fully understood by reading the subsequent detailed description and examples with reference made to the accompanying drawings, wherein: 
         FIG. 1  is a schematic diagram of a display panel; 
         FIG. 2  is a schematic diagram of a portion of the display panel of  FIG. 1 ; 
         FIG. 3  is a schematic diagram of an exemplary embodiment of a display device for displaying images; 
         FIG. 4   a  is a schematic diagram of a portion of the display device of  FIG. 3 ; 
         FIG. 4   b  is a schematic layout diagram of the embodiment of  FIG. 4   a;    
         FIG. 5   a  is a schematic diagram of another exemplary embodiment of a non-display pixel; 
         FIG. 5   b  is a schematic layout diagram of the embodiment of  FIG. 5   a ; and 
         FIG. 6  is a schematic diagram of another exemplary embodiment of a non-display pixel. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 3  is a schematic diagram of an exemplary embodiment of a display device for displaying images. In this embodiment, the display device is implemented as an electronic device  3 . By way of example, electronic device  3  can be a cellular phone, PDA (personal digital assistant), laptop computer, notebook computer, tablet computer, car TV, or digital camera, etc. Electronic device  3  comprises a gate driver  32 , a source driver  34 , and a display panel  36 . Gate driver  32  supplies scan signals S 1 ˜Sn to gate lines. Source driver  34  supplies data signals D 1 ˜Dm to source lines. Display panel  36  comprises a display area  362  and a non-display area  364 . In some embodiments, a display panel combines a gate driver with a source driver. 
       FIG. 4   a  is a schematic diagram of a portion (block  366 ) of the display device of  FIG. 3 . As shown in  FIG. 4   a , display area  362  comprises display pixels D 11 ˜D 12 . Each display pixel comprises at least one switching TFT. Non-display area  364  comprises non-display pixels N 11 ˜N 22 . Each non-display pixel comprises dummy TFTs. The number of the dummy TFTs of a first non-display pixel among the non-display pixels exceeds the number of the switching TFTs of a first display pixel among the display pixels. The number of the switching TFTs and that of the dummy TFTs are not limited. In this embodiment, each display pixel comprises one switching TFT and each non-display pixel comprises four dummy TFTs. 
     Display panel  36  can relieve electrostatic charge damage incrementally as the number of the dummy TFTs is increased. Although the number of the dummy TFTs exceeds the number of the switching TFTs, the area of one non-display pixel in non-display area  364  may be equal to the area of one display pixel in display area  362 . 
     Since the structures of non-display pixels N 11 ˜N 22  are the same, only non-display pixel N 11  is described here as an example. As shown in  FIG. 4   a , non-display pixel N 11  comprises dummy TFTs  401 ˜ 404 . Dummy TFT  401  is serially connected to dummy TFT  402  between source line  40  and capacitor  405 . Dummy TFT  403  is serially connected to dummy TFT  404  between nodes P 1  and P 2 . The states of nodes P 1  and P 2  are floating states. 
     When electrostatic charge is accumulated in a left end of a metal line  41  and reaches a preset value, a dielectric breakdown event occurs in the gates of dummy TFTs  401 ˜ 404  such that electrostatic charge is relieved by paths  411 ˜ 418 . Thus, electrostatic charge in the left end of metal line  41  is reduced as electrostatic charge is relieved by non-display pixel N 11 . 
     Since the number of the dummy TFTs of non-display pixel N 11  is increased, the majority of the electrostatic charge will be relieved by paths  411 ˜ 418 . Therefore, the breakdown event should not occur in the dummy TFTs of non-display pixel N 21  and display pixel D 11 . 
     When the number of the dummy TFTs of the non-display pixels is increased, the dummy TFTs can relieve more electrostatic charge. Therefore, the capability of relieving ESD of the non-display pixels is increased. 
     In some embodiments, the channel width or length of one dummy TFT is less than that of one switching TFT for easily triggering the dielectric breakdown event in the dummy TFTs. 
       FIG. 4   b  is a schematic layout diagram of an exemplary embodiment of non-display pixel N 11 . The gates of dummy TFTs  401 ˜ 404  are coupled to metal line  41 . Dummy TFT  401  is serially connected to dummy TFT  402  between source line  40  and capacitor  405 . Dummy TFT  403  is serially connected to dummy TFT  404  between nodes P 1  and P 2 . Dummy TFT  401  is parallel connected with dummy TFT  403 . Dummy TFT  402  is parallel connected with dummy TFT  404 . In some embodiments, dummy TFT  401  can be serially connected to dummy TFT  402  between floating nodes. 
       FIG. 5   a  is schematic diagram of another exemplary embodiment of the non-display pixel.  FIG. 5   b  is a schematic layout diagram of the embodiment of  FIG. 5   a . As shown in  FIGS. 5   a  and  5   b , the gates of dummy TFTs  501 ˜ 507  are coupled to gate line  51 . Dummy TFT  501  is serially connected to dummy TFTs  502  and  503  between source line  50  and capacitor  508 . Dummy TFT  504  is serially connected to dummy TFT  505  between nodes P 3  and P 4 . Dummy TFT  506  is serially connected to dummy TFT  507  between nodes P 5  and P 6 . The states of nodes P 3 ˜P 6  are floating states. Since  FIGS. 4   a  and  5   a  have the same principle, descriptions of  FIG. 5   a  is omitted. 
       FIG. 6  is a schematic diagram of another exemplary embodiment of a non-display pixel. As shown in  FIG. 6 , the gates of dummy TFTs  601 ˜ 609  are coupled to gate line  61 . Dummy TFT  601  is serially connected to dummy TFTs  602  and  603  between source line  60  and capacitor  610 . Dummy TFT  604  is parallel connected with dummy TFTs  605  and  606 . Dummy TFT  607  is parallel connected with dummy TFTs  608  and  609 . Dummy TFT  601  is parallel connected with dummy TFT  604 . Dummy TFT  603  is parallel connected with dummy TFT  607 . Since  FIGS. 4   a  and  6  have the same principle, descriptions of  FIG. 6  is omitted. 
     By way of example, different layout methods can be used to provide a number of dummy TFTs of one non-display pixel that exceeds the number of switching TFTs of one display pixel. 
     While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.