Patent Abstract:
A pixel array comprising a plurality of pixel groups, wherein each pixel group comprises: A plurality of light emitting elements, a plurality of driving units, and a plurality of switching units. A plurality of driving units, each of which outputs drives currents for the light emitting elements in a convolution sequence. Each of switching units couples the output of one of the driving units to the light emitting elements in the convolution sequence.

Full Description:
BACKGROUND OF THE INVENTION 
   1. Field of Invention 
   The present invention relates to intra-pixel convolution, and more particularly to intra-pixel convolution for AMOLED. 
   2. Description of Related Art 
   The use of organic materials in the electronics industry has increased recently and has led to low cost, high performance displays. Enhanced performance, such as increased luminance, has been achieved by using OLEDs. Furthermore, active-matrix OLEDs have been developed, resulting in brighter, larger and higher resolution OLED displays that dissipate less power than passive-matrix displays. However, the non-uniformity of the threshold voltage and mobility among the driving transistors seriously degrades the performance of the AMOLED display. Thus, a new AMOLED driving mechanism eliminating the non-uniformity issue is necessary. 
   SUMMARY OF THE INVENTION 
   An objective of the present invention is to provide a mechanism for driving an AMOLED display, which eliminating the performance degradation resulting from the non-uniformity of the threshold voltage and mobility. 
   The present invention provides a pixel array comprising a plurality of pixel groups, wherein each pixel group comprises a plurality of light emitting elements, a plurality of driving units, and a plurality of switching units. Each of the driving units outputs driving currents for the light emitting elements in a convolution sequence. Each of switching units couples the output of one of the driving units to the light emitting elements in the convolution sequence. 
   The present invention also provides a method for driving a display having a pixel array comprising a plurality of pixel groups, wherein each pixel group comprises a plurality of light emitting elements and a plurality of driving units, and the driving units are connected to data and scan lines to receive data and scan signals so that driving currents are generated in response to the data and scan signals, the method comprising the steps of outputting driving currents for the light emitting elements by the driving units in a convolution sequence, and coupling outputs of the driving units to the light emitting elements in the convolution sequence, wherein the driving units of each pixel group are connected to three adjacent data lines and two adjacent scan lines. 
   The present invention further provides another method for driving a display having a pixel array comprising a plurality of pixel groups, wherein each pixel group comprises a plurality of light emitting elements and a plurality of driving units, and the driving units are connected to data and scan lines to receive data and scan signals so that driving currents are generated in response to the data and scan signals, the method comprising the steps of outputting driving currents for the light emitting elements by the driving units in a convolution sequence, and coupling outputs of the driving units to the light emitting elements in the convolution sequence, wherein the driving units of each pixel group are connected to two adjacent data lines and three adjacent scan lines. 
   In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. 
       FIG. 1  is a circuit diagram of a pixel group of a pixel array according to a first embodiment of the present invention. 
       FIG. 2  shows the intra-pixel convolution of the pixel array illustrated in  FIG. 1 . 
       FIG. 3A  is a circuit diagram of a pixel group of a pixel array according to a second embodiment of the present invention. 
       FIG. 3B  is a circuit diagram of a pixel group of a pixel array according to a third embodiment of the present invention. 
       FIG. 4  is a circuit diagram of a pixel group of a pixel array according to a forth embodiment of the present invention. 
       FIG. 5  shows the intra-pixel convolution of the pixel array illustrated in  FIG. 4 . 
       FIG. 6  is a circuit diagram of a pixel group of a pixel array according to a fifth embodiment of the present invention. 
       FIG. 7  shows the intra-pixel convolution of the pixel array illustrated in  FIG. 6 . 
       FIG. 8  is a circuit diagram of a pixel group of a pixel array according to a sixth embodiment of the present invention. 
       FIG. 9  shows the intra-pixel convolution of the pixel array illustrated in  FIG. 8 . 
       FIG. 10A  shows the intra-pixel convolution of a pixel array according to a seventh embodiment of the present invention. 
       FIG. 10B  shows the intra-pixel convolution of a pixel array according to an eighth embodiment of the present invention. 
       FIG. 10C  shows the intra-pixel convolution of a pixel array according to a ninth embodiment of the present invention. 
   

   DESCRIPTION OF EMBODIMENTS 
   The present invention will now be described with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. The invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Furthermore, the embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. OLED is taken as an example in the embodiments to illustrate the operating principle of the present invention. However, the embodiments of the present invention are not limited to the OLED, i.e., any light emitting elements in this field is also suitable to be used in the present invention, such as AMOLED (active matrix organic light emitting diode) and LED. 
   In the drawings, whenever the same element reappears in subsequent drawings, it is denoted by the same reference numeral. 
     FIG. 1  is a circuit diagram of a pixel group of a pixel array according to a first embodiment of the present invention. The pixel array is divided to a plurality of pixel groups. A pixel group  100  includes driving units  11  and  12 , switching units  13  and  14 , and OLEDs  15  and  16 . The driving unit  11  includes a PMOS transistor  111  and the driving unit  12  includes a PMOS transistor  121 . The switching unit  13  includes PMOS transistors  131  and  132  and the switching unit  14  includes PMOS transistors  141  and  142 . The transistor  111  receives the data signal VDATA 11  to generate and to output driving currents for the OLEDs  15  and  16 . The transistor  121  receives the data signal VDATA 12  to generate and to output driving currents for the OLEDs  15  and  16 . The transistor  131  receives the switching signal SW 11  and the transistor  132  receives the switching signal SW 12 . The transistor  141  receives the switching signal SW 12  and the transistor  142  receives the switching signal SW 11 . The driving unit  11  and the driving unit  12  are powered by a supply voltage VDD. The cathodes of the OLEDs  15  and  16  are coupled to a ground voltage VSS. 
   Those skilled in the art should understand that the transistors are not limited to PMOS transistors, but also may be NMOS transistors or BJTs (bipolar junction transistors. 
     FIG. 2  shows the intra-pixel convolution of the pixel array illustrated in  FIG. 1 . In a first frame, the transistor  111  outputs a driving current for the OLED  15  and the transistor  121  outputs a driving current for the OLED  16 . The transistors  132  and  141  are turned off by the switching signal SW 12  while the transistors  131  and  142  are turned on by the switching signal SW 11 . Thus, the OLEDs  15  and  16  are driven by the driving units  11  and  12  respectively. In the following second frame, the transistor  111  outputs a driving current for the OLED  16  and the transistor  121  outputs a driving current for the OLED  15 . The transistors  132  and  141  are turned on by the switching signal SW 12  while the transistors  131  and  142  are turned off by the switching signal SW 11 . Thus, the OLEDs  15  and  16  are driven by the driving units  12  and  11  respectively. The operation is similar for another pixel group  200 , wherein the transistors  211  and  221  output driving currents for the OLEDs  17  and  18 . Since each of the OLEDs in a pixel group are driven by different driving units in a convolution sequence, the threshold voltages and mobility of the driving transistors in the same pixel group are averaged so that the performance degradation resulting from the non-uniformity issue is alleviated. 
     FIG. 3A  is a circuit diagram of a pixel group of a pixel array according to a second embodiment of the present invention. The pixel array is divided to a plurality of pixel groups. A pixel group  300 A includes driving units  31  and  32 , switching units  33  and  34 , and OLEDs  35  and  36 . The driving units  31  and  32  of the pixel group  300 A are commonly connected to a scan line to receive a scan signal SCAN 31 . The driving unit  31  includes transistors  311  and  313  and a capacitor  312 . The capacitor  312  is connected to a source of the transistor  311  and a gate of the transistor  313 . The driving unit  32  includes transistors  321  and  323  and a capacitor  322 . The capacitor  322  is coupled to a source of the transistor  321  and a gate of transistor  323 . The switching unit  33  includes transistors  331  and  332  and the switching unit  34  includes transistors  341  and  342 . The transistor  311  receives the scan signal SCAN 31  and a data signal VDATA 31  to generate and to output driving currents for the OLEDs  35  and  36 . The transistor  321  receives the scan signal SCAN 31  and a data signal VDATA 32  to generate and to output driving currents for the OLEDs  35  and  36 . The transistor  331  receives a switching signal SW 31  and the transistor  332  receives a switching signal SW 32 . The transistor  341  receives the switching signal SW 32  and the transistor  342  receives the switching signal SW 31 . The switching unit  33  and the switching unit  34  are electrically connected to the anodes of the OLEDs  35  and  36 . The driving units  31  and  32  are coupled to a supply voltage VDD. The cathodes of the OLEDs  35  and OLED  36  are coupled to a ground voltage VSS. 
     FIG. 3B  is a circuit diagram of a pixel group of a pixel array according to a third embodiment of the present invention. A pixel group  300 B includes driving units  37  and  38 , switching units  33  and  34 , and OLEDs  35  and  36 . The driving unit  37  includes transistor  371 ,  373 ,  374 , and  375  and a capacitor  372 . The capacitor  372  is connected to a gate of the transistor  373  and a source of the transistor  374 . The driving unit  38  includes transistors  381 ,  383 ,  384 , and  385  and a capacitor  382  The transistor  371  receives a scan signal SCAN 32  and a data signal VDATA 31  to generate and to output driving currents for the OLEDs  35  and  36 . The transistor  381  receives a scan signal SCAN 32  and a data signal VDATA 32  to generate and to output driving currents for the OLEDs  35  and  36 . The capacitor  382  is connected to a gate of the transistor  383  and a source of the transistor  384 . The switching unit  33  includes transistors  331  and  332  and the switching unit  34  includes transistors  341  and  342 . The transistor  331  receives the switching signal SW 31  and the transistor  332  receives the switching signal SW 32 . The transistor  341  receives the switching signal SW 32  and the transistor  342  receives the switching signal SW 31 . The switching unit  33  and the switching unit  34  are electrically connected to the anodes of the OLEDs  35  and  36 . The driving units  31  and  32  are coupled to a supply voltage VDD. The cathodes of the OLEDs  35  and  36  are coupled to a ground voltage VSS. 
     FIG. 4  is a circuit diagram of a pixel group of a pixel array according to a forth embodiment of the present invention. The driving units  41  and  42  of the pixel group  400  are commonly connected to a data line to receive a data signal VDATA 41 . The pixel array is divided to a plurality of pixel groups. A pixel group  400  includes driving units  41  and  42 , switching units  43  and  44  and OLEDs  45  and  46 . The driving unit  41  includes transistors  411  and  413  and a capacitor  412 . The capacitor  412  is connected to a source of the transistor  411  and a gate of the transistor  413 . The driving unit  42  includes transistors  421  and  423  and a capacitor  422 . The capacitor  422  is connected to a source of the transistor  421  and a gate of the transistor  423 . The switching unit  43  includes transistors  431  and  432  and the switching unit  44  includes transistors  441  and  442 . The transistor  411  receives a scan signal SCAN 41  and the data signal VDATA 41  to generate and to output driving currents for the OLEDs  45  and  46 . The transistor  421  receives a scan signal SCAN 42  and the data signal VDATA 41  to generate and to output driving currents for the OLEDs  45  and  46 . The transistor  431  receives a switching signal SW 41  and the transistor  432  receives a switching signal SW 42 . The transistor  441  receives the switching signal SW 42  and the transistor  442  receives the switching signal SW 41 . The switching units  43  and  44  are electrically connected the anodes of the OLEDs  45  and  46 . The driving units  41  and  42  are coupled to a supply voltage VDD. The cathodes of the OLEDs  45  and  46  are coupled to a ground voltage VSS. However, the conventional pixel array reduces the quality of LCD panels. 
     FIG. 5  shows the intra-pixel convolution of the pixel array illustrated in  FIG. 4 . In a first frame, the transistor  411  outputs a driving current for the OLED  45  and the transistor  421  outputs a driving current for the OLED  46 . The transistors  432  and  441  are turned off by the switching signal SW 42  while the transistors  431  and  442  are turned on by the switching signal SW 41 . Thus, the OLEDs  45  and  46  are driven by the driving units  41  and  42  respectively. In the following second frame, the transistor  411  outputs a driving current for the OLED  46  and the transistor  421  outputs a driving current for the OLED  45 . The transistors  432  and  441  are turned on by the switching signal SW 42  while the transistors  431  and  442  are turned off by the switching signal SW 41 . Thus, the OLEDs  45  and  46  are driven by the driving units  42  and  41  respectively. The operation is similar for another pixel group, wherein the transistors  511  and  512  output driving currents for the OLEDs  55  and  56 . 
     FIG. 6  is a circuit diagram of a pixel group of a pixel array according to a fifth embodiment of the present invention. The pixel array is divided to a plurality of pixel groups. A pixel group  600  includes driving units  61  and  62 , switching units  63  and  64  and OLEDs  65  and  66 . The driving unit  61  includes transistors  611  and  613  and a capacitor  612 . The capacitor  612  is connected to a source of the transistor  611  and a gate of the transistor  613 . The driving unit  62  includes transistors  621  and  623  and a capacitor  622 . The capacitor  622  is coupled to a source of the transistor  621  and a gate of the transistor  623 . The switching unit  63  includes transistors  631  and  632  and the switching unit  64  includes transistors  641  and  642 . The transistor  611  receives a scan signal SCAN 61  a data signal VDATA 61  to generate and to output driving currents for the OLEDs  65  and  66 . The transistor  621  receives a scan signal SCAN 62  and a data signal VDATA 62  to generate and to output driving currents for the OLEDs  65  and  66 . The transistor  631  receives a switching signal SW 61  and the transistor  632  receives a switching signal SW 62 . The transistor  641  receives the switching signal SW 62  and the transistor  642  receives the switching signal SW 61 . The switching units  63  and  64  are electrically connected the anodes of the OLEDs  65  and  66 . The driving units  61  and  62  are coupled to a supply voltage VDD. The cathodes of the OLEDs  65  and  66  are coupled to a ground voltage VSS. However, the conventional pixel array reduces the quality of LCD panels. 
     FIG. 7  shows the intra-pixel convolution of the pixel array illustrated in  FIG. 6 . In a first frame, the transistor  611  outputs a driving current for the OLED  65  and the transistor  621  outputs a driving current for the OLED  66 . The transistors  632  and  641  are turned off by the switching signal SW 62  while the transistors  631  and  642  are turned on by the switching signal SW 61 . Thus, the OLEDs  65  and  66  are driven by the driving units  61  and  62  respectively. In the following second frame, the transistor  611  outputs a driving current for the OLED  66  and the transistor  621  outputs a driving current for the OLED  65 . The transistors  632  and  641  are turned on by the switching signal SW 62  while the transistors  631  and  642  are turned off by the switching signal SW 61 . Thus, the OLEDs  65  and  66  are driven by the driving units  62  and  61  respectively. The operation is similar for another pixel group, wherein the transistors  711  and  712  output driving currents for the OLEDs  75  and  76 . 
     FIG. 8  is a circuit diagram of a pixel group of a pixel array according to a sixth embodiment of the present invention. The pixel array is divided to a plurality of pixel groups. A pixel array  800  includes driving units  81 ,  82 , and  83 , switching units  84 ,  85 , and  86 , and OLEDs  87 ,  88 , and  89 . The driving unit  81  includes a transistor  811 , the driving unit  82  includes a transistor  821 , and the driving unit  83  includes a transistor  831 . The transistor  811  receives a data signal VDATA 81  to generate and to output driving currents for the OLED  87 ,  88 , and  89 . The transistor  821  receives a data signal VDATA 82  to generate and to output driving currents for the OLED  87 ,  88 , and  89 . The transistor  831  receives a data signal VDATA  83  to generate and to output driving currents for the OLED  87 ,  88 , and  89 . The switching unit  84  includes transistors  841   842 , and  843 . The switching unit  85  includes transistors  851 ,  852 , and  853 . The switching unit  86  includes transistors  861 ,  862 , and  863 . The transistors  841 ,  853 , and  863  receive a switching signal SW 81 . The transistors  842 ,  852 , and  862  receive a switching signal SW 82 . The transistors  843 ,  851 , and  861  receive a switching signal SW 83 . The switching units  84 ,  85 , and  86  are electrically connected the anodes of the OLEDs  87 ,  88 , and  89 . The driving units  81 ,  82 , and  83  are coupled to a supply voltage VDD. The cathodes of the OLEDs  87 ,  88 , and  89  are coupled to a ground voltage VSS. 
     FIG. 9  shows the intra-pixel convolution of the pixel array illustrated in  FIG. 8 . In a first frame, the transistor  841  outputs a driving current for the OLED  87 , the transistor  853  outputs a driving current for the OLED  88  and the transistor  863  outputs a driving current for the OLED  89 . The transistors  842 ,  852  and  862  are turned off by the switching signal SW 82 , and the transistors  843 , 851  and  861  are turned off by the switching signal SW 83  while the transistors  841 ,  853  and  863  are turned on by the switching signal SW 81 . Thus, the OLEDs  87 ,  88  and  89  are driven by the driving units  81 ,  82  and  83  respectively. In the second frame, the transistor  842  outputs a driving current for the OLED  88 , the transistor  852  outputs a driving current for the OLED  89  and the transistor  862  outputs a driving current for the OLED  87 . The transistors  841 ,  853  and  863  are turned off by the switching signal SW 81 , and the transistors  843 , 851  and  861  are turned off by the switching signal SW 83  while the transistors  842 ,  852  and  862  are turned on by the switching signal SW 82 . Thus, the OLEDs  87 ,  88  and  89  are driven by the driving units  83 ,  81  and  82  respectively. 
   In the third frame, the transistor  843  outputs a driving current for the OLED  89 , the transistor  851  outputs a driving current for the OLED  87  and the transistor  861  outputs a driving current for the OLED  88 . The transistors  841 ,  853  and  863  are turned off by the switching signal SW 81 , and the transistors  842 ,  852  and  862  are turned off by the switching signal SW 82  while the transistors  843 ,  851  and  861  are turned on by the switching signal SW 83 . Thus, the OLEDs  87 ,  88  and  89  are driven by the driving units  82 ,  83  and  81  respectively. The operation is similar for another pixel group, wherein the transistors  911 ,  921  and  931  output driving currents for the OLEDs  97 ,  98  and  99 . 
     FIG. 10A  shows the intra-pixel convolution of a pixel array according to a seventh embodiment of the present invention. The number of the driving units of the pixel group is 3, and the 3 driving units of each pixel group are connected to three adjacent data lines and two adjacent scan lines. In a first frame, the transistor T 1  outputs a driving current for the OLED  1 , the transistor T 2  outputs a driving current for the OLED  2  and the transistor T 3  outputs a driving current for the OLED  3 . In the second frame, the transistor T 3  outputs a driving current for the OLED  1 , the transistor T 1  outputs a driving current for the OLED  2  and the transistor T 2  outputs a driving current for the OLED  3 . In the third frame, the transistor T 2  outputs a driving current for the OLED  1 , the transistor T 3  outputs a driving current for the OLED  2  and the transistor T 1  outputs a driving current for the OLED  3 . The operation is similar for another pixel group, wherein the transistors T 4 , T 5  and T 6  output driving currents for the OLEDs  4 ,  5  and  6 . 
     FIG. 10B  shows the intra-pixel convolution of a pixel array according to an eighth embodiment of the present invention. The number of the driving units of the pixel group is 3, and the 3 driving units of each pixel group are connected to three adjacent data lines and two adjacent scan lines. In a first frame, the transistor T 1  outputs a driving current for the OLED  1 , the transistor T 2  outputs a driving current for the OLED  2  and the transistor T 3  outputs a driving current for the OLED  3 . In the second frame, the transistor T 3  outputs a driving current for the OLED  1 , the transistor T 1  outputs a driving current for the OLED  2  and the transistor T 2  outputs a driving current for the OLED  3 . In the third frame, the transistor T 2  outputs a driving current for the OLED  1 , the transistor T 3  outputs a driving current for the OLED  2  and the transistor T 1  outputs a driving current for the OLED  3 . The operation is similar for another pixel group, wherein the transistors T 4 , T 5  and T 6  output driving currents for the OLEDs  4 ,  5  and  6 . 
     FIG. 10C  shows the intra-pixel convolution of a pixel array according to a ninth embodiment of the present invention. The number of the driving units of the pixel group is 3, and the 3 driving units of each pixel group are connected to two adjacent data lines and three adjacent scan lines. In a first frame, the transistor T 1  outputs a driving current for the OLED  1 , the transistor T 2  outputs a driving current for the OLED  2  and the transistor T 3  outputs a driving current for the OLED  3 . In the second frame, the transistor T 3  outputs a driving current for the OLED  1 , the transistor T 1  outputs a driving current for the OLED  2  and the transistor T 2  outputs a driving current for the OLED  3 . In the third frame, the transistor T 2  outputs a driving current for the OLED  1 , the transistor T 3  outputs a driving current for the OLED  2  and the transistor T 1  outputs a driving current for the OLED  3 . The operation is similar for another pixel group, wherein the transistors T 4 , T 5  and T 6  output driving currents for the OLEDs  4 ,  5  and  6 . 
   To sum up, as each of the switching units coupling the pixel array in the convolution sequence, the intra-pixel convolution for AMOLED balances the threshold voltage and reduces the mobility variation. 
   Though the present invention has been disclosed above by the preferred embodiments, they are not intended to limit the invention. Anybody skilled in the art can make some modifications and variations without departing from the spirit and scope of the invention. Therefore, the protecting range of the invention falls in the appended claims.

Technology Classification (CPC): 6