Driving method of active matrix display device

• US 7,336,249 B2
• Filed: 06/27/2005
• Issued: 02/26/2008
• Est. Priority Date: 03/26/1996
• Status: Expired due to Fees

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Hirakata, Yoshiharu, Takemura, Yasuhiko
• Primary Examiner(s): Hjerpe; Richard
• Assistant Examiner(s): Nguyen; Jennifer T
• Application Number:
  US11/166,339
• Publication Number:
  US 20060017679A1
• Time in Patent Office: 974 Days
• Field of Search: 345/87, 345/89, 345 90- 96, 345/204, 345208-210, 345211-213
• US Class Current: 345/87
• CPC Class Codes: G09G 2300/0434 Flat panel display in which a field is applied parallel to the display plane
• CPC Class Codes: G09G 2330/025 Reduction of instantaneous peaks of current
• CPC Class Codes: G09G 2330/04 Display protection
• 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 3/3655 Details of drivers for counter electrodes, e.g. common electrodes for pixel capacitors or supplementary storage capacitors
• CPC Class Codes: G09G 3/3659 the addressing of the pixel involving the control of two or more scan electrodes or two or more data electrodes, e.g. pixel voltage dependant on signal of two data electrodes

Abstract

In a liquid crystal display device of the in-plane switching mode (IPS mode), the potential of data that is output from a data driver is set at values between potentials that are given to common lines. Two levels, i.e., high and low levels, are prepared for the potential to be given to the common lines and the potential is inverted between those levels in every field, whereby the polarity of a voltage between both electrodes of a pixel is inverted. As a result, the potential variation ranges of signals that are output from the data driver and a scan driver can be greatly reduced from those of the conventional case, which contributes to reduction in the power consumption of the drivers. Since the voltage applied to a switching element for controlling each pixel can be reduced, the load of the switching element can also be reduced.

Claims

1. A method for driving an active matrix display device comprising:

applying a potential V_p to a data line P_m for a pixel electrode;

applying a potential V_H to a common line Y_n; and

changing said potential V_H for said common line Y_n to a potential V_L before or at the same time when a first selection pulse V_x for a first field is applied to a scan line X_n corresponding to said data line P_m and said common line Y_n,

wherein each of said potentials V_H and V_L applied to said common line Y_n is different from a standard voltage Vc, and

wherein said potential V_p to said data line P_m satisfies a condition V_L≦

V_p≦

V_H.

2. A method according to claim 1, wherein said active matrix display device is operated by a field inverting mode.

3. A method according to claim 1, wherein said common line Y_n is kept at said potential V_H or V_L during 80% or more of one field period.

4. A method according to claim 1, wherein said common line Y_n is kept at said potential V_H or V_L during 95% or more of one field period.

5. A method according to claim 1, wherein both of said potentials V_H and V_L are lower than a threshold voltage of a liquid crystal material included in said active matrix display device.

6. A method according to claim 1, wherein said data line, scan line, common line and pixel electrode are formed over a substrate.

7. A method according to claim 1, wherein said potential V_p to said data line P_m produces signals of a single polarity.

8. A method for driving an active matrix display device comprising:

applying a potential V_p to a data line P_m fox a pixel electrode;

applying a potential V_H to a common line Y_n;

changing said potential V_H for said common line Y_n to a standard voltage V_c before a first selection pulse V_X for a first field is applied to a scan line X_n corresponding to said data line P_m and said common line Y_n; and

changing said potential Vc for said common line Y_n to a potential V_L at the same time when the first selection pulse V_X to said scan line X_n,

wherein said potential V_p to said data line P_m satisfies a condition V_L≦

V_p≦

V_H.

9. A method according to claim 8, wherein said potentials V_H, V_C, and V_L satisfy an inequality, V_H>

V_C>

V_L.

10. A method according to claim 8, wherein said active matrix display device is operated by a field inverting mode.

11. A method according to claim 8, wherein said common line Y_n is kept at said potential V_H or V_L during 80% or more of one field period.

12. A method according to claim 8, wherein said common line Y_n is kept at said potential V_H or V_L during 95% or more of one field period.

13. A method according to claim 8, wherein both of said potentials V_H and V_L are lower than a threshold voltage of a liquid crystal material included in said active matrix display device.

14. A method according to claim 8, wherein said data line, scan fine, common line and pixel electrode are formed over a substrate.

15. A method according to claim 8, wherein said potential V_p to said data line P_m produces signals of a single polarity.

16. A method for driving an active matrix display device comprising a pixel portion having a plurality of scan lines, a plurality of data lines, a plurality of common lines, a plurality of switching elements for switching pixel electrodes over a substrate, said method comprising:

applying a potential V_p to a data line P_m for a pixel electrode;

applying a potential V_Y to a common line Y_n; and

inverting said potential V_Y for said common line Y_n before or at the same time when a first selection pulse V_X for a fist field is applied to a scan line X_n corresponding to said data line P_m and said common line Y_n,

wherein a value of said potential V_Y for said common line Y_n equals a potential (V_offset+V_amp) or V_offset, wherein said V_amp is a potential of an image information, and

wherein said potential V_p to said data line P_m satisfies a condition V_L≦

V_p≦

V_H.

17. A method according to claim 16, wherein said active matrix display device is operated by a field inverting mode.

18. A method according to claim 16, wherein said common line Y_n is kept at said potential (V_offset+V_amp) or −

;

V_offset to be superimposed on said potential V_p during 80% or more of one field period.

19. A method according to claim 16, wherein said common line Y_n is kept at said potential (V_offset+V_amp) or −

;

V_offset to be superimposed on said potential V_p during 95% or more of one field period.

20. A method according to claim 16, wherein said potential V_Y for said common line Y_n is lower than a threshold voltage of a liquid crystal material included in said active matrix display device.

21. A method according to claim 16, wherein said potential V_p to said data line P_m produces signals of a single polarity.

22. A method for driving an active matrix display device comprising:

applying a potential V_p to a data line P_m connected to a source of a pixel thin film transistor over a substrate;

applying a potential V_H to a common line Y_n over said substrate; and

changing said potential V_H of said common line Y_n to a potential V_L before or at the same time when a first selection pulse V_X for a first field is applied to a scan line X_n connected to a gate of said pixel Thin film transistor,

wherein each of said potentials V_H and V_L applied to said common line Y_n is different from a standard voltage Vc, and

wherein said potential V_p to said data line P_m satisfies a condition V_L≦

V_p≦

V_H.

23. A method according to claim 22, wherein said active matrix display device is operated by a field inverting mode.

24. A method according to claim 22, wherein said common line Y_n is kept at said potential V_H or V_L during 80% or more of one field period.

25. A method according to claim 22, wherein said common line Y_n is kept at said potential V_H or V_L during 95% or more of one field period.

26. A method according to claim 22, wherein both of said potentials V_H and V_L are lower than a threshold voltage of a liquid crystal material included in said active matrix display device.

27. A method according to claim 22, wherein said potential V_p to said data line P_m produces signals of a single polarity.

28. A method for driving an active matrix display device comprising:

applying a potential V_p to a data line P_m connected to a source of a pixel thin film transistor over a substrate;

applying a potential V_H to a common line Y_n over said substrate;

changing said potential V_H of said common line Y_n to a standard voltage V_c before a first selection pulse V_X for a first field is applied to a scan line X_n connected to a gate of said pixel thin film transistor; and

changing said potential Vc of said common line Y_n to a potential V_L at the same time when the first selection pulse V_X to said scan line X_n,

wherein said potential V_p to said data line P_m satisfies a condition V_L≦

V_p≦

V_H.

29. A method according to claim 28, wherein said potentials V_H, V_C, and V_L satisfy art inequality, V_H>

V_C>

V_L.

30. A method according to claim 28, wherein said active matrix display device is operated by a field inverting mode.

31. A method according to claim 28, wherein said common line Y_n is kept at said potential V_H or V_L during 80% or more of one field period.

32. A method according to claim 28, wherein said common line Y_n is kept at said potential V_H or V_L during 95% or more of one field period.

33. A method according to claim 28, wherein both of said potentials V_H and V_L are lower than a threshold voltage of a liquid crystal material included in said active matrix display device.

34. A method according to claim 28, wherein said potential V_p to said data line P_m produces signals of a single polarity.

35. A method for driving an active matrix display device comprising the steps of:

applying a potential V_p to a data line P_m for a pixel electrode;

applying a potential V_Y to a common line Y_n; and

changing said potential V_Y for said common line Y_n to a potential V_H or V_L before or at the same time when a first selection pulse V_X for a first field is applied to a scan line X_n corresponding to said data line P_m and said common line Y_n,

wherein said V_H and V_L are maximum and minimum potentials given to said common lines, respectively,

wherein said potential V_p to said data line P_m satisfies a condition V_L≦

V_p≦

V_H.

36. A method according to claim 35, wherein said active matrix display device is operated by a field inverting mode.

37. A method according to claim 35, wherein said common line Y_n is kept at said potential V_H or V_L during 80% or more of one field period.

38. A method according to claim 35, wherein said common line Y_n is kept at said potential V_H or V_L during 95% or more of one field period.

39. A method according to claim 35, wherein said potential V_Y for said common line Y_n is lower than a threshold voltage of a liquid crystal material included in said active matrix display device.

40. A method according to claim 35, wherein said potential V_p to said data line P_m produces signals of a single polarity.