Display device

• US 20070115245A1
• Filed: 11/17/2006
• Published: 05/24/2007
• Est. Priority Date: 11/18/2005
• Status: Active Grant

• Current Assignee: Panasonic Intellectual Property Corporation of America (Panasonic Holdings Corporation)
• Original Assignee: Panasonic Liquid Crystal Display Company Limited (Panasonic Holdings Corporation)
• Inventors: Miyazawa, Toshio, Maki, Masahiro, Sato, Hideo, Nakao, Takayuki
• Granted Patent: US 7,764,264 B2
• Time in Patent Office: Days
• US Class Current: 345/100
• CPC Class Codes: G09G 2310/0267 Details of drivers for scan electrodes, other than drivers for liquid crystal, plasma or OLED displays
• CPC Class Codes: G09G 2310/0283 Arrangement of drivers for different directions of scanning
• CPC Class Codes: G09G 3/20 for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
• CPC Class Codes: G09G 3/3677 suitable for active matrices only
• CPC Class Codes: G11C 19/184 with field-effect transistors, e.g. MOS-FET

Abstract

The present invention provides a display device that has a driving circuit including a single channel bidirectional shift register with which the circuit scale can be reduced without increasing the number of elements. The driving circuit includes a single channel bidirectional shift register. This single channel bidirectional shift register has an RS flip-flop circuit. The RS flip-flop circuit includes a first transistor having a first electrode connected to an output terminal and having a second electrode to which a second scanning direction control signal is applied and a second transistor having a first electrode connected to an output terminal and having a second electrode to which a first scanning direction control signal is applied. In this circuit configuration, a resetting signal is applied to a control electrode of the first transistor in a first scanning direction, a setting signal is applied to the control electrode of the first transistor in a second scanning direction which is a direction opposite to the first scanning direction. The setting signal is also applied to a control electrode of the second transistor in the first scanning direction, and the resetting signal is also applied to the control electrode of the second transistor in the second scanning direction.

Claims

1. A display device comprising:

a plurality of pixels; and

a driving circuit for driving the plurality of pixels;

wherein;

the driving circuit includes a single channel bidirectional shift register adapted for bidirectional scanning in a first direction and a second direction;

the single channel bidirectional shift register includes an RS flip-flop circuit;

the RS flip-flop circuit includes a first transistor having a first electrode connected to an output terminal and having a second electrode to which a second scanning direction control signal is applied, and a second transistor having a first electrode connected to an output terminal and having a second electrode to which a first scanning direction control signal is applied;

a resetting signal is applied to a control electrode of the first transistor in a first scanning direction, and a setting signal is applied to the control electrode of the first transistor in a second scanning direction which is a reverse direction to the first scanning direction; and

the setting signal is also applied to a control electrode of the second transistor in the first scanning direction, and the resetting signal is also applied to the control electrode of the second transistor in the second scanning direction.

31. The display device according to claim 1, wherein:

each of the transistors is an n-type of transistor; and

when the reference potential is defined as an L-level and an H-level is defined as a voltage level of a potential higher than the reference potential,

in the first scanning direction, a voltage level of a first scanning direction control signal is the H-level and a voltage level of a second scanning direction control signal is the L-level, and

in the second scanning direction, a voltage level of a first scanning direction control signal is the L-level and a voltage level of a second scanning direction control signal is the H-level.

32. The display device according to claim 1, wherein:

each of the transistors is a p-type of transistor; and

when the reference potential is defined as an H-level and an L-level is defined as a voltage level of a potential lower than the reference potential,

in the first scanning direction, a voltage level of a first scanning direction control signal is the L-level and a voltage level of a second scanning direction control signal is the H-level, and

in the second scanning direction, a voltage level of a first scanning direction control signal is the H-level and a voltage level of a second scanning direction control signal is the L-level.

33. The display device according to claim 1, wherein the driving circuit is a scan line driving circuit that scans each of the pixels for each display line.

34. The display device according to claim 1, wherein the driving circuit is an image line driving circuit that supplies an image voltage to each of the pixels.

2. A display device comprising:

a plurality of pixels; and

a driving circuit for driving the plurality of pixels;

wherein;

the driving circuit includes a single channel bidirectional shift register adapted for bidirectional scanning in a first direction and a second direction;

the single channel bidirectional shift register includes an “

n”

number of basic circuits tandem-connected in multiple stages (wherein “

n”

is equal to or greater than 2);

the basic circuits each include a first RS flip-flop circuit and a second RS flip-flop circuit;

the first RS flip-flop circuit includes a first transistor having a first electrode connected to an output terminal, a second electrode connected to a second scanning control line to which a second scanning direction control signal is supplied, and a control electrode connected to an output terminal of any basic circuit on the side of a preceding stage in the first scanning direction, and a second transistor having a first electrode connected to an output terminal, a second electrode connected to a first scanning control line to which a first scanning direction control signal is supplied, and a control electrode connected to an output terminal of any basic circuit on the side of a following stage in the first scanning direction;

the second RS flip-flop circuit includes a third transistor having a first electrode connected to an output terminal, a second electrode connected to the second scanning control line, and a control electrode connected to an output terminal of any other basic circuit on the side of the following stage side in the first scanning direction, and a fourth transistor having a first electrode connected to an output terminal, a second electrode connected to the first scanning control line, and a control electrode connected to an output terminal of any other basic circuit on the side of the preceding stage in the first scanning direction.

3. The display device according to claim 2, wherein each of the basic circuits includes:

a fifth transistor having a control electrode connected to an output terminal of the first RS flip-flop circuit, a second electrode connected to an output terminal of the second RS flip-flop circuit, and a first electrode connected to a reference potential line to which a reference potential is supplied;

a sixth transistor having a control electrode connected to the second electrode of the fifth transistor, a first electrode connected to a clock terminal, and a second electrode connected to an output terminal of the basic circuit; and

a first capacitive element connected between the control electrode of the sixth transistor and the second electrode thereof.

4. The display device according to claim 3, wherein each of the basic circuits includes a seventh transistor having a first electrode connected to the reference potential line, a second electrode connected to the control electrode of the fifth transistor, and a control electrode connected to the control electrode of the sixth transistor.

5. The display device according to claim 3, wherein each of the basic circuits includes an eighth transistor having a control electrode and a second electrode each connected to a frame signal line to which a starting signal of a frame is supplied, and having a first electrode connected to the control electrode of the fifth transistor.

6. The display device according to claim 3, wherein each of the basic circuits includes a second capacitive element connected between the reference potential line and the control electrode of the fifth transistor.

7. The display device according to claim 3, wherein each of the basic circuits includes:

a ninth transistor connected between the control electrode of the sixth transistor and the second electrode of the fifth transistor, the ninth transistor having a control electrode connected to the first scanning control line; and

a tenth transistor connected between the control electrode of the sixth transistor and the second electrode of the fifth transistor, the tenth transistor having a control electrode connected to the second scanning control line.

8. The display device according to claim 3, wherein each of the basic circuits includes an eleventh transistor having a control electrode connected to the control electrode of the sixth transistor, a first electrode connected to a clock terminal, and a second electrode connected to an external output terminal.

9. The display device according to claim 8, wherein each of the basic circuits includes:

a twelfth transistor having a first electrode to which the reference potential is applied, and a second electrode connected to the second electrode of the eleventh transistor;

a thirteenth transistor having a first electrode connected to the control electrode of the twelfth transistor, a second electrode connected to the second scanning control line, and a control electrode connected to an external output terminal of an immediately preceding basic circuit in the first scanning direction; and

a fourteenth transistor having a first electrode connected to the control electrode of the twelfth transistor, a second electrode connected to the first scanning control line, and a control electrode connected to an external output terminal of an immediately following basic circuit in the first scanning direction.

10. The display device according to claim 9, wherein each of the basic circuits includes a fifteenth transistor having a control terminal and a second electrode each connected to the frame signal line, and a first electrode connected to the control electrode of the twelfth transistor.

11. The display device according to claim 9, wherein each of the basic circuits includes a third capacitive element connected between the reference potential line and the control electrode of the twelfth transistor.

12. The display device according to claim 3, wherein each of the basic circuits includes:

a sixteenth transistor having a control electrode connected to the control electrode of the sixth transistor, a first electrode connected to a clock terminal, and a second electrode connected to a first external output terminal; and

a seventeenth transistor having a control electrode connected to the control electrode of the sixth transistor, a first electrode connected to a clock terminal, and a second electrode connected to a second external output terminal.

13. The display device according to claim 12, wherein each of the basic circuits includes:

an eighteenth transistor having a first electrode connected to the reference potential line and a second electrode connected to the second electrode of the sixteenth transistor;

a nineteenth transistor having a first electrode connected to the reference potential line and a second electrode connected to the second electrode of the seventeenth transistor;

a twentieth transistor having a first electrode connected to the control electrodes of the eighteenth and nineteenth transistors, a second electrode connected to the second scanning control line, and a control electrode connected to a second external output terminal of an immediately preceding basic circuit in the first scanning direction; and

a twenty-first transistor having a first electrode connected to the control electrodes of the eighteenth and nineteenth transistors, a second electrode connected to the first scanning control line, and a control electrode connected to a second external output terminal of an immediately following basic circuit in the first scanning direction.

14. The display device according to claim 13, wherein each of the basic circuits includes a twenty-second transistor having a control terminal and a second electrode each connected to the frame signal line, and a first electrode connected to the control electrodes of the eighteenth and nineteenth transistors.

15. The display device according to claim 13, wherein each of the basic circuits includes a fourth capacitive element connected between the reference potential line and the control electrodes of the eighteenth and nineteenth transistors.

16. The display device according to claim 3, wherein:

a clock terminal of a basic circuit at an odd-numbered stage in the first scanning direction is connected to a first clock signal line to which a first clock signal is supplied;

a clock terminal of a basic circuit at an even-numbered stage in the first scanning direction is connected to a second clock signal line to which a second clock signal is supplied; and

the first clock signal and the second clock signal are of the same period and differ in phase.

17. The display device according to claim 3, wherein the basic circuit located at the (n−

2)th stage based on the third stage in the first scanning direction is configured such that;

the control electrode of the first transistor is connected to an output terminal of the basic circuit located at the second preceding stage;

the control electrode of the second transistor is connected to an output terminal of the basic circuit located at the second following stage;

the control electrode of the third transistor is connected to an output terminal of the basic circuit located at the first following stage; and

the control electrode of the fourth transistor is connected to an output terminal of the basic circuit located at the first preceding stage.

18. The display device according to claim 17, further comprising a twenty-third transistor having a control electrode connected to the frame signal line and a first electrode connected to the second clock signal line, wherein the basic circuit at the first stage in the first scanning direction is configured such that:

the control electrode of the first transistor is connected to the frame signal line;

the control electrode of the second transistor is connected to an output terminal of the basic circuit located at the third stage;

the control electrode of the third transistor is connected to an output terminal of the basic circuit located at the second stage; and

the control electrode of the fourth transistor is connected to a second electrode of the twenty-third transistor.

19. The display device according to claim 18, wherein the basic circuit at the second stage in the first scanning direction is configured such that:

the control electrode of the first transistor is connected to the second electrode of the twenty-third transistor;

the control electrode of the second transistor is connected to an output terminal of the basic circuit located at the fourth stage;

the control electrode of the third transistor is connected to an output terminal of the basic circuit located at the third stage; and

the control electrode of the fourth transistor is connected to an output terminal of the basic circuit located at the first stage.

20. The display device according to claim 18, wherein the basic circuit at the second stage in the first scanning direction is configured such that:

the control electrode of the first transistor is connected to the frame signal line;

the control electrode of the second transistor is connected to an output terminal of the basic circuit located at the fourth stage;

the control electrode of the third transistor is connected to an output terminal of the basic circuit located at the third stage; and

the control electrode of the fourth transistor is connected to an output terminal of the basic circuit located at the first stage.

21. The display device according to claim 18, further comprising a fifth capacitive element connected between the control electrode of the twenty-third transistor and the reference potential line.

22. The display device according to claim 18, further comprising a twenty-fourth transistor having a control electrode connected to the second scanning control line, and a first electrode and a second electrode each connected to the second electrode of the twenty-third transistor.

23. The display device according to claim 17, further comprising a twenty-fifth transistor having a control electrode connected to the frame signal line and a first electrode connected to the first clock signal line, wherein if “

n”

is an even number, the basic circuit located at the nth stage in the first scanning direction is configured such that;

the control electrode of the first transistor is connected to an output terminal of the basic circuit located at the (n−

2)th stage;

the control electrode of the second transistor is connected to the frame signal line;

the control electrode of the third transistor is connected to a second electrode of the twenty-fifth transistor; and

the control electrode of the fourth transistor is connected to an output terminal of the basic circuit located at the (n−

1)th stage.

24. The display device according to claim 23, wherein:

in the first scanning direction, after the starting signal of the frame has become valid, a voltage level of the first clock signal changes first and then a voltage level of the second clock signal changes; and

in the second scanning direction, after the starting signal of the frame has become valid, the voltage level of the second clock signal changes first and then the voltage level of the first clock signal changes.

25. The display device according to claim 17, further comprising a twenty-fifth transistor having a control electrode connected to the frame signal line and a first electrode connected to the second clock signal line, wherein if “

n”

is an odd number, the basic circuit located at the nth stage in the first scanning direction is configured such that;

the control electrode of the first transistor is connected to an output terminal of the basic circuit located at the (n−

2)th stage;

the control electrode of the second transistor is connected to the frame signal line;

the control electrode of the third transistor is connected to a second electrode of the twenty-fifth transistor; and

the control electrode of the fourth transistor is connected to an output terminal of the basic circuit located at the (n−

1)th stage.

26. The display device according to claim 25, wherein:

in the first scanning direction or in the second scanning direction, after the starting signal of the frame has become valid, a voltage level of the second clock signal changes first and then a voltage level of the first clock signal changes.

27. The display device according to claim 23, wherein the basic circuit located at the (n−

1)th stage in the first scanning direction is configured such that;

the control electrode of the first transistor is connected to an output terminal of the basic circuit located at the (n−

3)th stage;

the control electrode of the second transistor is connected to a second electrode of the twenty-fifth transistor;

the control electrode of the third transistor is connected to an output terminal of the basic circuit located at the nth stage; and

the control electrode of the fourth transistor is connected to an output terminal of the basic circuit located at the (n−

2)th stage.

28. The display device according to claim 23, wherein the basic circuit located at the (n−

1)th stage in the first scanning direction is configured such that;

the control electrode of the first transistor is connected to an output terminal of the basic circuit located at the (n−

3)th stage;

the control electrode of the second transistor is connected to the frame signal line;

the control electrode of the third transistor is connected to an output terminal of the basic circuit located at the nth stage; and

the control electrode of the fourth transistor is connected to an output terminal of the basic circuit located at the (n−

2)th stage.

29. The display device according to claim 23, further comprising a sixth capacitive element connected between the second electrode of the twenty-fifth transistor and the reference potential line.

30. The display device according to claim 23, further comprising a twenty-sixth transistor having a control electrode connected to the second scanning control line, and a first electrode and a second electrode each connected to the second electrode of the twenty-fifth transistor.