ACTIVE-MATRIX DEVICE

Abstract

A display device includes a driving transistor for supplying driving current to a display element; a first switch connecting the driving transistor to a corresponding data line; a second switch selectively connecting a control electrode of the driving transistor to one of two main electrodes of the driving transistor; and a third switch connecting the driving transistor to the display element in one pixel. The first switch is controlled by a first control line. The second and third switches each include two switching elements connected in series controlled by the first control line and a second control line, respectively. Four functions of writing of data in the pixel, light emission of the display element by supplying current, non-light emission of the display element, and examination of the pixel operation can be switched using the two control lines.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates pixel circuits and circuits in the vicinity thereof in a display device according to an exemplary embodiment of the present invention, and FIG. 1B illustrates one of the pixel circuits.

FIG. 2 is a block diagram illustrating the entire structure of the display device according to the exemplary embodiment of the present invention.

FIG. 3 is a timing chart illustrating the operations of the pixel circuits shown in FIG. 1A.

FIG. 4 is a timing chart illustrating other operations of the pixel circuits shown in FIG. 1A.

FIG. 5 illustrates a modification of the pixel circuits in the display device according to the exemplary embodiment of the present invention.

FIG. 6 illustrates another modification of the pixel circuits in the display device according to the exemplary embodiment of the present invention.

FIG. 7 is a schematic cross-sectional view of a TFT used in the display device according to the exemplary embodiment of the present invention.

FIG. 8 illustrates a pixel circuit and a current-detecting circuit used in a display device according to an example of the present invention.

Claims

1. A display device comprising: a matrix that includes a plurality of rows and columns of pixels, each pixel including a display element and a driving circuit arranged to drive the display element;a plurality of pairs of control lines, each pair being associated with at least one corresponding row of the pixels and including a first control line and a second control line; anda plurality of data lines, each data line being associated with at least one corresponding column of the pixels,wherein the driving circuit of each pixel comprises:a driving transistor including at least first and second main electrodes and a control electrode,at least one first switch operable to switchably connect a corresponding one of the data lines to the first main electrode of the driving transistor,at least one second switch operable to switchably connect the first main electrode of the driving transistor to the control electrode of the driving transistor, andat least one third switch operable to switchably connect the first main electrode of the driving transistor to the display element of the driving circuit,wherein the first and second control lines associated with the row of the pixel are arranged to control the switches such that the at least one first switch and at least part of the at least one second switch are opened or closed at the same time, and such that at least part of the at least one second switch and at least part of the at least one third switch are opened or closed at the same time.

2. The display device according to claim 1, wherein the at least one second switch and the at least one third switch each include first and second switching elements connected in series, the first and second switching elements forming parts of the at least one second switch and the at least one third switch.

3. The display device according to claim 2, wherein the first control line associated with the row of the pixel is connected to the first switch, the first switching element of the at least one second switch, and the first switching element of the at least one third switch.

4. The display device according to claim 3, wherein the second control line associated with the row of the pixel is connected to the second switching element of the at least one second switch and the second switching element of the at least one third switch.

5. The display device according to claim 1, wherein the first and second control lines also control the switches to close the at least one first switch and at least part of the at least one second switch and open at least part of the at least one third switch to perform a current data programming operation in which a driving signal provided on the data line associated with the pixel is provided through the first and second main electrodes of the driving transistor and stored in a storage device.

6. The display device according to claim 5, wherein the first and second control lines also control the switches to open the at least one first switch and the at least one second switch and close the at least one third switch so that the driving signal drives the display element to cause it to emit light.

7. The display device according to claim 6, wherein the first and second control lines also control the switches to close the at least one first, second, and third switches so that no driving signal drives the display element, and so that the display element does not emit light.

8. The display device according to claim 7, wherein the first and second control lines also control the switches to close the at least one first switch and open the at least second and third switches to perform pixel-current testing in which a signal passes across the first and second main electrodes of the driving transistor towards a current measuring device.

9. The display device according to claim 8, wherein the current measuring device detects a current of the signal.

10. The display device according to claim 1, wherein a current measuring device is electrically coupled to each data line to measure a current thereon.

11. The display device according to claim 10, wherein the current is measured for at least one column at a time in sequence.

12. The display device according to claim 2, wherein the at least one first, second, and third switches are formed of thin-film transistors,wherein the at least one first switch and the first switching element of the at least one second switch have the same channel polarity, andwherein the at least one first switching element of the at least one third switch has a channel polarity opposite to that of the first switching element of the at least one second switch.

13. A method of operating a driving circuit arranged to drive a display element, the driving circuit including a driving transistor including at least first and second main electrodes and a control electrode, at least one first switch operable to switchably connect a corresponding data line to the first main electrode of the driving transistor, at least one second switch operable to switchably connect the first main electrode of the driving transistor to the control electrode of the driving transistor, and at least one third switch operable to switchably connect the first main electrode of the driving transistor to the display element, the method comprising closing the at least one first switch and at least part of the at least one second switch and opening at least part of the at least one third switch to perform a current data programming operation in which a driving signal provided on a data line is provided through the first and second main electrodes of the driving transistor and stored in a storage device.

14. The method of claim 13, further comprising opening the at least one first switch and at least part of the at least one second switch and closing at least part of the at least one third switch so that the driving signal drives the display element to cause it to emit light.

15. The method according to claim 14, further comprising closing the at least one first, second, and third switches so that no driving signal drives the display element, and so that the display element does not emit light.

16. The method according to claim 15, further comprising closing the at least one first switch and opening the at least one second and third switches to perform pixel-current testing in which a signal passes across the first and second main electrodes of the driving transistor towards a current measuring device.

17. The method according to claim 16, further comprising measuring a current of the signal.