Display device

Abstract

A display device which stores display data for every display pixel can reduce the number of transistors which constitute 1 display pixel. In a display device which includes a display panel having a plurality of display pixels, video lines which apply video data to the display pixels and scanning lines which apply a scanning voltage to the display pixels, the display pixel includes: a capacitive element which holds a voltage corresponding to a value of the video data; a pixel electrode; a first transistor of a first conductive type which is connected between a first power source line and the pixel electrode and, at the same time, has a control electrode to which the voltage held in the capacitive element is applied; and a second transistor of a second conductive type different from the first conductive type which is connected between a second power source line and the pixel electrode and, at the same time, has a control electrode to which the voltage held in the capacitive element is applied. Here, a first voltage is supplied to the first power source line, and a second voltage is supplied to the second power source line. The second voltage is a voltage which is obtained by inverting the first voltage.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing the schematic constitution of a display device of an embodiment 1 according to the present invention;

FIG. 2 is a view showing an equivalent circuit of a display pixel of the display device of the embodiment 1 according to the present invention;

FIG. 3 is a view showing the relationship between a voltage of VCOM and a voltage of a VCOMB which is obtained by inverting the voltage of VCOM of the display device of the embodiment 1 according to the present invention;

FIG. 4 is a block diagram showing the schematic constitution of a display device of an embodiment 2 according to the present invention;

FIG. 5 is a view showing an equivalent circuit of a display pixel of the display device of the embodiment 2 according to the present invention;

FIG. 6 is a view showing the circuit constitution of a VCOM selector circuit shown in FIG. 4;

FIG. 7A and FIG. 7B are views showing the constitution of a display pixel of a display device of the embodiment 3 according to the present invention; and

FIG. 8 is an equivalent circuit diagram showing the constitution of 1 display pixel of a display device which is already proposed by inventors of the present invention.

Claims

1. A display device which includes a display panel having a plurality of display pixels, video lines which apply video data to the display pixels and scanning lines which apply a scanning voltage to the display pixels, wherein the display pixel includes:a capacitive element which holds a voltage corresponding to a value of the video data;a pixel electrode;a first transistor of a first conductive type which is connected between a first power source line and the pixel electrode and, at the same time, has a control electrode to which the voltage held in the capacitive element is applied; anda second transistor of a second conductive type different from the first conductive type which is connected between a second power source line and the pixel electrode and, at the same time, has a control electrode to which the voltage held in the capacitive element is applied, whereina first voltage is supplied to the first power source line, anda second voltage is supplied to the second power source line, the second voltage being a voltage which is obtained by inverting the first voltage.

2. A display device according to claim 1, wherein the display pixel includes an active element which is turned off when a non-selective scanning voltage is applied to the scanning line and is turned on when a selective scanning voltage is applied, and a voltage corresponding to the value of the video data is applied to the capacitive element from the video line via the active element.

3. A display device according to claim 1, wherein the video data assumes binary values of “1” and “0”, and when the video data assumes “1”, the first transistor is turned on and the second transistor is turned off, while when the video data assumes “0”, the first transistor is turned off and the second transistor is turned on.

4. A display device according to claim 1, wherein the display pixel includes a common electrode which faces the pixel electrode in an opposed manner, and the first voltage is applied to the common electrode.

5. A display device according to claim 1, wherein the first voltage has a voltage level thereof inverted from a High level to a Low level or from the Low level to the High level at a predetermined inversion cycle.

6. A display device according to claim 1, wherein M pieces of display pixels constitute one sub pixel, and areas of the pixel electrodes of the respective M pieces of display pixels which constitute one sub pixel differ from each other.

7. A display device according to claim 6, wherein the video data is video data of m(m≧2) bits, M is m, and weighting is applied to the areas of the pixel electrodes of the respective M pieces of display pixels which constitute 1 sub pixel substantially at a rate of 20:21: , . . . , :2(m−1).

8. A display device which includes a display panel having a plurality of display pixels, video lines which apply video data to the display pixels and scanning lines which apply a scanning voltage to the display pixels, the display pixel includes:a pixel electrode;a first transistor of a first conductive type which is connected between a first power source line and the pixel electrode and, at the same time, has a control electrode to which the voltage corresponding to the value of the video data is applied; anda second transistor of a second conductive type different from the first conductive type which is connected between a second power source line and the pixel electrode and, at the same time, has a control electrode to which the voltage corresponding to the value of the video data is applied, andeither one of a first voltage and a second voltage is supplied to the first power source line, andanother one of the first voltage and the second voltage is supplied to the second power source line, the second voltage being a voltage which is obtained by inverting the first voltage.

9. A display device according to claim 8, wherein the display pixel includes an active element which is turned off when a non-selective scanning voltage is applied to the scanning line and is turned on when a selective scanning voltage is applied, and a voltage corresponding to the value of the video data is applied to the control electrodes of the first transistor and the second transistor from the video line via the active element.

10. A display device according to claim 8, wherein the video data assumes binary values of “1” and “0”, and when the video data assumes “1”, the first transistor is turned on and the second transistor is turned off, while when the video data assumes “0”, the first transistor is turned off and the second transistor is turned on.

11. A display device according to claim 8, wherein the first transistor, when the first transistor assumes an ON state and, thereafter, the voltage corresponding to the value of the video data is not applied to the control electrode, maintains the ON state due to a voltage held in a first parasitic capacitance between the first electrode and the control electrode of the first transistor, and the second transistor, when the second transistor assumes an ON state and, thereafter, the voltage corresponding to the value of the video data is not applied to the control electrode, maintains the ON state due to a voltage held in a second parasitic capacitance between the first electrode and the control electrode of the second transistor.

12. A display device according to claim 8, wherein the display pixel includes a common electrode which faces the pixel electrode in an opposed manner and the first voltage is applied to the common electrode.

13. A display device according to claim 8, wherein the first voltage has a voltage level thereof inverted from a High level to a Low level or from the Low level to the High level at a predetermined inversion cycle.

14. A display device according to claim 8, wherein when a voltage level of the first voltage assumes a Low level, the first voltage is supplied to the first power source line and the second voltage is supplied to the second power source line, while when a voltage level of the first voltage assumes a High level, the second voltage is supplied to the first power source line and the first voltage is supplied to the second power source line.

15. A display device according to claim 14, wherein the display device includes a selection circuit which selects the first voltage or the second voltage as the voltage supplied to the first power source line and the second power source line in response to the voltage level of the first voltage.

16. A display device according to claim 8, wherein the display device includes a data inversion circuit which inverts the video data in response to the voltage level of the first voltage.

17. A display device according to claim 16, wherein the data inversion circuit does not invert the video data when the voltage level of the first voltage assumes the Low level and inverts the video data when the voltage level of the first voltage assumes the High level.

18. A display device according to claim 8, wherein M pieces of display pixels constitute 1 sub pixel, and M pieces of display pixels which constitute 1 sub pixel make areas of the respective pixel electrodes thereof different from each other.

19. A display device according to claim 18, wherein the video data is video data of m(m≧2) bits, M is m, and weighting is applied to the areas of the pixel electrodes of the respective M pieces of display pixels which constitute 1 sub pixel substantially at a rate of 20:21: , . . . , :2(m−1).

20. A display device according to claim 8, wherein the display device is a liquid crystal display device.