Semiconductor display device and method of driving semiconductor display device

• US 7,098,884 B2
• Filed: 02/08/2001
• Issued: 08/29/2006
• Est. Priority Date: 02/08/2000
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Onoya, Shigeru
• Primary Examiner(s): Eisen, Alexander
• Application Number:
  US09/778,761
• Publication Number:
  US 20010034075A1
• Time in Patent Office: 2,028 Days
• Field of Search: 345 87-100, 345/208, 345/209
• US Class Current: 345/96
• CPC Class Codes: G09G 2320/0219 Reducing feedthrough effects in active matrix panels, i.e. voltage changes on the scan electrode influencing the pixel voltage due to capacitive coupling
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• CPC Class Codes: G09G 3/3614 Control of polarity reversal in general
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 3/3666 with the matrix divided into sections
• CPC Class Codes: H01L 27/12 the substrate being other than a semiconductor body, e.g. an insulating body
• CPC Class Codes: H01L 27/1214 comprising a plurality of TFTs formed on a non-semiconducting substrate, e.g. driving circuits for AMLCDs

Abstract

A semiconductor display device with which flicker, vertical striping, and horizontal striping are not easily seen, and a method of driving the semiconductor display device, are provided. Display signals inputted to a plurality of pixel electrodes have a positive or negative polarity based on the electric potential of an opposing electrode, and pixel electrodes to which display signals having a positive polarity are inputted, and pixel electrodes to which display signals having a negative polarity are inputted, differ for each frame period with the method of driving the semiconductor display device.

Claims

1. A method of driving a semiconductor display device, the semiconductor display device comprising:

an opposing electrode;

a plurality of pixels, each of which comprises;

a pixel TFT;

a pixel electrode; and

a liquid crystal formed between the pixel electrode and the opposing electrode; and

a plurality of signal lines, each of which is electrically connected to at least one of the pixel TFTs,

the method comprising the steps of;

inputting display signals to the pixel electrodes of the pixels through the pixel TFTs; and

displaying an image corresponding to the display signals during a frame period,

wherein each of the display signals has one of a positive polarity and a negative polarity relative to an electric potential of the opposing electrode in accordance with a polarity pattern;

wherein the polarity pattern is maintained during the frame period, and irregularly changed to another polarity pattern after the frame period;

wherein the display signals having a same polarity are input to the pixel electrodes through the pixel TFTs connected to one of the plurality of signal lines;

wherein polarities of the display signals are independently controlled in each of the plurality of signal lines; and

wherein polarities of the display signals input to the pixel electrodes through the pixel TFTs connected to one of the plurality of signal lines are changed together.

2. A method of driving a semiconductor display device according to claim 1, wherein a polarity of display signals input to only some of the pixel electrodes changes in two adjacent frame periods.

3. A method of driving a semiconductor display device, the semiconductor display device comprising:

an opposing electrode;

a plurality of pixels, each of which comprises;

a pixel TFT;

a pixel electrode; and

a liquid crystal formed between the pixel electrode and the opposing electrode; and

a plurality of signal lines, each of which is electrically connected to at least one of the pixel TFTs,

the method comprising the steps of;

inputting display signals to the pixel electrodes of the pixels through the pixel TFTs; and

displaying an image corresponding to the display signals during a frame period,

wherein each of the display signals has one of a positive polarity and a negative polarity relative to an electric potential of the opposing electrode in accordance with a polarity pattern;

wherein the polarity pattern is maintained during the frame period, and irregularly changed to the another polarity pattern after the frame period so that flicker becomes difficult to observe;

wherein the display signals having a same polarity are input to the pixel electrodes through the pixel TFTs connected to one of the plurality of signal lines;

wherein polarities of the display signals are independently controlled in each of the plurality of signal lines; and

wherein polarities of the display signals input to the pixel electrodes through the pixel TFTs connected to one of the plurality of signal lines are changed together.

4. A method of driving a semiconductor display device according to claim 3, wherein a polarity of display signals input to only some of the pixel electrodes changes in two adjacent frame periods.

5. A method of driving a semiconductor display device, the semiconductor display device comprising:

an opposing electrode;

a plurality of pixels, each of which comprises;

a pixel TFT;

a pixel electrode; and

a liquid crystal formed between the pixel electrode and the opposing electrode; and

a plurality of signal lines, each of which is electrically connected to at least one of the pixel TFTs,

the method comprising the steps of;

inputting display signals to the pixel electrodes of the pixels through the pixel TFTs; and

displaying an image corresponding to the display signals during a frame period,

wherein each of the display signals has one of a positive polarity and a negative polarity relative to an electric potential of the opposing electrode in accordance with a polarity pattern;

wherein the polarity pattern is maintained during the frame period, and irregularly changed to another polarity pattern after the frame period so that vertical striping becomes difficult to observe;

wherein the display signals having a same polarity are input to the pixel electrodes through the pixel TFTs connected to one of the plurality of signal lines;

wherein polarities of the display signals are independently controlled in each of the plurality of signal lines; and

wherein polarities of the display signals input to the pixel electrodes through the pixel TFTs connected to one of the plurality of signal lines are changed together.

6. A method of driving a semiconductor display device according to claim 5, wherein a polarity of display signals input to only some of the pixel electrodes changes in two adjacent frame periods.

7. A method of driving a semiconductor display device, the semiconductor display device comprising:

an opposing electrode;

a plurality of pixels, each of which comprises;

a pixel TFT;

a pixel electrode; and

a liquid crystal formed between the pixel electrode and the opposing electrode; and

a plurality of signal lines, each of which is electrically connected to at least one of the pixel TFTs,

the method comprising the steps of;

inputting display signals to the pixel electrodes of the pixels through the pixel TETs; and

displaying an image corresponding to the display signals during a frame period,

wherein each of the display signals has one of a positive polarity and a negative polarity relative to an electric potential of the opposing electrode in accordance with a polarity pattern;

wherein the polarity pattern is maintained during the frame period, and randomly changed to another polarity pattern after the frame period; and

wherein polarities of the display signals input to the pixel electrodes through the pixel TFTs connected to the one of the plurality of signal lines are changed together.

8. A method of driving a semiconductor display device according to claim 7, wherein a polarity of display signals input to only some of the pixel electrodes changes in two adjacent frame periods.

9. A method of driving a semiconductor display device according to claim 7, wherein the polarity of display signals input to all of the pixel electrodes in the vertical line is changed randomly in the certain fixed period.

10. A method of driving a semiconductor display device according to claim 7, wherein the polarities of display signals input to multiple ones of the vertical lines of pixel electrodes are changed randomly in the certain fixed period.

11. A semiconductor display device comprising:

a source signal line driver circuit;

a gate signal line driver circuit;

a plurality of source signal lines;

a plurality of gate signal lines;

a pixel portion; and

a display signal generation portion,

wherein the pixel portion has a plurality of pixels, each containing a pixel TFT and a pixel electrode;

wherein the display signal generation portion comprises a control portion, a polarity data signal generation portion, an alternating current signal generation portion, a display signal election portion, a + side display signal generation portion, and a −

side display signal generation portion,

wherein display signals are generated in the display signal generating portion and input to the plurality of source signal lines through the source signal line driver circuit;

wherein an image corresponding to the display signals is displayed during a frame period;

wherein a polarity pattern corresponding to the display signals is maintained during the frame period, and irregularly changed to another polarity pattern after the frame period;

wherein the display signals having a same polarity are input to the pixel electrodes through the pixel TFTs connected to one of the plurality of source signal lines;

wherein polarities of the display signals are independently controlled in each of the plurality of source signal lines; and

wherein polarities of the display signals input to the pixel electrodes through the pixel TFTs connected to one of the plurality of source signal lines are changed together.

12. A semiconductor display device according to claim 11, wherein a polarity of display signals input to only some of the pixel electrodes changes in two adjacent frame periods.

13. A semiconductor display device comprising:

a source signal line driver circuit;

a gate signal line driver, circuit;

a plurality of source signal lines;

a plurality of gate signal lines;

a pixel portion; and

a display signal generation portion,

wherein the pixel portion has a plurality of pixels, each containing a pixel TFT and a pixel electrode;

wherein the display signal generation portion comprises a control portion, a polarity data signal generation portion, an alternating current signal generation portion, a display signal selection portion, a + side display signal generation portion, and a −

side display signal generation portion,

wherein display signals are generated in the display signal generating portion and input to the plurality of source signal lines through the source signal line driver circuit;

wherein an image corresponding to the display signals is displayed during a frame period;

wherein a polarity pattern corresponding to the display signals is maintained during the frame period, and irreparably changed to another polarity pattern after the frame period so that flicker becomes difficult to observe;

wherein the display signals having a same polarity are input to the pixel electrodes through the pixel TFTs connected to one of the plurality of source signal lines;

wherein polarities of the display signals are independently controlled in each of the plurality of source signal lines; and

wherein polarities of the display signals input to the pixel electrodes through the pixel TFTs connected to one of the plurality of source signal lines are changed together.

14. A semiconductor display device according to claim 13, wherein a polarity of display signals input to only some of the pixel electrodes changes in two adjacent frame periods.

15. A semiconductor display device comprising:

a source signal line driver circuit;

a gate signal line driver circuit;

a plurality of source signal lines;

a plurality of gate signal lines;

a pixel portion; and

a display signal generation portion,

wherein the pixel portion has a plurality of pixels, each containing a pixel TFT and a pixel electrode;

wherein the display signal generation portion comprises a control portion, a polarity data signal generation portion, an alternating current signal generation portion, a display signal selection portion, a + side display signal generation portion, and a −

side display signal generation portion,

wherein display signals are generated in the display signal generating portion and input to the plurality of source signal lines through the source signal line driver circuit;

wherein an image corresponding to the display signals is displayed during a frame period;

wherein a polarity pattern corresponding to the display signals is maintained during the frame period, and irregularly changed to another polarity pattern after the frame period so that vertical striping becomes difficult to observe;

wherein the display signals having a same polarity are input to the pixel electrodes through the pixel TFTs connected to one of the plurality of source signal lines;

wherein polarities of the display signals are independently controlled in each of the plurality of source signal lines; and

wherein polarities of the display signals input to the pixel electrodes through the pixel TFTs connected to one of the plurality of source signal lines are changed together.

16. A semiconductor display device according to claim 15, wherein a polarity of display signals input to only some of the pixel electrodes changes in two adjacent frame periods.

17. A semiconductor display device comprising:

a source signal line driver circuit;

a gate signal line driver circuit;

a plurality of source signal lines;

a plurality of gate signal lines;

a pixel portion; and

a display signal generation portion,

wherein the pixel portion has a plurality of pixels, each containing a pixel TFT and a pixel electrode;

wherein the display signal generation portion comprises a control portion, a polarity data signal generation portion, an alternating current signal generation portion, a display signal selection portion, a + side display signal generation portion, and a −

side display signal generation portion,

wherein display signals are generated in the display signal generating portion and input to the plurality of source signal lines through the source signal line driver circuit;

wherein an image corresponding to the display signals is displayed during a frame period;

wherein a polarity pattern corresponding to the display signals is maintained during the frame period, and randomly changed to another polarity pattern after the frame period; and

wherein polarities of the display signals input to the pixel electrodes through the pixel TETs connected to one of the plurality of source signal lines are changed together.

18. A semiconductor display device according to claim 17, wherein a polarity of display signals input to only some of the pixel electrodes changes in two adjacent frame periods.

19. A semiconductor display device according to claim 17, wherein the polarity of display signals input to all of the pixel electrodes in the vertical line is changed randomly in the certain fixed period.

20. A semiconductor display device according to claim 17, wherein the polarities of display signals input to multiple ones of the vertical lines of pixel electrodes are changed randomly in the certain fixed period.

21. A method of driving a semiconductor display device, the semiconductor display device comprising:

an opposing electrode;

a plurality of pixels, each of which comprises;

a pixel TFT;

a pixel electrode; and

a liquid crystal formed between the pixel electrode and the opposing electrode; and

a plurality of signal lines, each of which is electrically connected to at least one of the pixel TFTs,

the method comprising the steps of;

inputting display signals to the pixel electrodes of the pixels through the pixel TFTs; and

displaying an image corresponding to the display signals during a frame period,

wherein each of the display signals has one of a positive polarity and a negative polarity relative to an electric potential of the opposing electrode in accordance with a polarity pattern;

wherein the polarity pattern is maintained during the frame period, and randomly changed to another polarity pattern after the frame period so that flicker becomes difficult to observe; and

wherein polarities of the display signals input to the pixel electrodes through the pixel TFTs connected to one of the plurality of signal lines are changed together.

22. A method of driving a semiconductor display device according to claim 21, wherein a polarity of display signals input to only some of the pixel electrodes changes in two adjacent frame periods.

23. A method of driving a semiconductor display device according to claim 21, wherein the polarity of display signals input to all of the pixel electrodes in the vertical line is changed randomly in the certain fixed period.

24. A method of driving a semiconductor display device according to claim 21, wherein the polarities of display signals input to multiple ones of the vertical lines of pixel electrodes are changed randomly in the certain fixed period.

25. A semiconductor display device comprising:

a source signal line driver circuit;

a gate signal line driver circuit;

a plurality of source signal lines;

a plurality of gate signal lines;

a pixel portion; and

a display signal generation portion,

wherein the pixel portion has a plurality of pixels, each containing a pixel TFT and a pixel electrode;

wherein the display signal generation portion comprises a control portion, a polarity data signal generation portion, an alternating current signal generation portion, a display signal selection portion, a + side display signal generation portion, and a −

side display signal generation portion,

wherein display signals are generated in the display signal generating portion and input to the plurality of source signal lines through the source signal line driver circuit;

wherein an image corresponding to the display signals is displayed during a frame period;

wherein a polarity pattern corresponding to the display signals is maintained during the frame period, and randomly changed to another polarity pattern after the frame period so that flicker becomes difficult to observe; and

wherein polarities of the display signals input to the pixel electrodes through the pixel TETs connected to one of the plurality of source signal lines are changed together.

26. A semiconductor display device according to claim 25, wherein a polarity of display signals input to only some of pixel electrodes have an inverse polarity in two adjacent frame periods.

27. A semiconductor display device according to claim 25, wherein the polarity of display signals input to all of the pixel electrodes in the vertical line is changed randomly in the certain fixed period.

28. A semiconductor display device according to claim 25, wherein the polarities of display signals input to multiple ones of the vertical lines of pixel electrodes are changed randomly in the certain fixed period.

29. A semiconductor display device comprising:

a source signal line driver circuit;

a gate signal line driver circuit;

a plurality of source signal lines;

a plurality of gate signal lines;

a pixel portion; and

a display signal generation portion,

wherein the pixel portion has a plurality of pixels, each containing a pixel TFT and a pixel electrode;

wherein the display signal generation portion comprises a control portion, a polarity data signal generation portion, an alternating current signal generation portion, a display signal selection portion, a + side display signal generation portion, and a −

side display signal generation portion,

wherein display signals are generated in the display signal generating portion and input to the plurality of source signal lines through the source signal line driver circuit;

wherein an image corresponding to the display signals is displayed during a frame period;

wherein a polarity pattern corresponding to the display signals is maintained during the frame period, and irreparably changed to another polarity pattern after the frame period so that vertical striping becomes difficult to observe;

wherein polarities of the display signals input to pixel electrodes through the pixel TFTs connected to the one of the plurality of signal lines are changed together.

30. A semiconductor display device according to claim 29, wherein a polarity of display signals input to only some of pixel electrodes have an inverse polarity in two adjacent frame periods.

31. A semiconductor display device according to claim 29, wherein the polarity of display signals input to all of the pixel electrodes in the vertical line is changed randomly in the certain fixed period.

32. A semiconductor display device according to claim 29, wherein the polarities of display signals input to multiple ones of the vertical lines of pixel electrodes are changed randomly in the certain fixed period.

33. A method of driving a semiconductor display device comprising a plurality of pixels, each containing a pixel TFT and a pixel electrode;

an opposing electrode; and

a liquid crystal formed between the pixel electrode and the opposing electrode;

wherein display signals are input to the pixel electrode through the pixel TFT,

wherein each of the display signals input to the pixel electrode has one of a positive polarity and a negative polarity, with an electric potential of the opposing electrode as a standard,

wherein the pixel electrodes are arranged in multiple vertical lines and polarities of the display signals input to pixel electrodes in a vertical line change together, and

wherein a particular polarity of display signals input to the pixels electrodes in the vertical line is changed randomly in a certain fixed period, to an extent that vertical striping becomes difficult to observe.

34. A method of driving a semiconductor display device according to claim 33, wherein only some of pixel electrodes have an inverse polarity in two adjacent frame periods.

35. A method of driving a semiconductor display device according to claim 33, wherein the polarity of display signals input to all of the pixel electrodes in the vertical line is changed randomly in the certain fixed period.

36. A method of driving a semiconductor display device according to claim 33, wherein the polarities of display signals input to multiple ones of the vertical lines of pixel electrodes are changed randomly in the certain fixed period.