Active matrix structure for display screen and screen comprising one such matrix

1. An active matrix structure for a display screen, formed on a transparent substrate, comprising:

pixel electrodes arranged in rows and columns;

a switching device associated with each electrode, and corresponding row selection lines, each selection line being disposed between two rows of successive pixel electrodes, said selection lines and electrode pixels being realized on a different level of a structure;

under each row of pixel electrodes, a bus made of conducting and transparent material, substantially with a same width as said row, produced on a level of the structure separated from a level of the selection lines and from a level of the pixel electrodes by at least one insulation layer and connected to the selection line of a previous row of pixel electrodes, said bus forming a storage capacitor with each pixel electrode of said row; and

a channel level of the transistors is situated between a level of the storage capacitor bus and that of the row selection lines forming gate of the transistors.

2. The active matrix structure as claimed in claim 1 , wherein each storage capacitor bus is connected to a previous row selection line outside an active zone of the matrix, at at least one end.

3. The active matrix structure as claimed in claim 2 , wherein each storage capacitor bus is connected at its two ends to said previous row selection line, outside the active zone.

4. The active matrix structure as claimed in claim 1 , wherein each storage capacitor bus is connected to said row selection line at the level of each pixel element of the associated row.

5. The active matrix structure as claimed in claim 1 , wherein the switching devices are transistors, the selection line of a row forming a gate for each of the transistors of the row.

6. The active matrix structure as claimed in claim 5 , wherein for each transistor of a row, a portion at least of the storage capacitor bus of the following row overlaps the channel of the transistor, said portion of bus operating as a second gate for said transistor.

7. The active matrix structure as claimed in claim 6 , for a transistor of type with a gate below, wherein the storage capacitor bus is produced on a level disposed above the levels of the selection lines and the data lines.

8. A display screen comprising an active matrix structure as claimed in claim 7 .

9. The active matrix structure as claimed in claim 6 , for a transistor of type with a gate above, wherein the storage capacitor bus is produced on a level disposed below the levels of the selection lines and the data lines, directly on a substrate, or on an optical mask level.

10. A display screen comprising an active matrix structure as claimed in claim 9 .

11. The active matrix structure as claimed in claim 5 , wherein for each transistor of a row, a portion at least of the storage capacitor bus of the row overlaps the channel of the transistor, said portion of bus operating as a second gate for said transistor.

12. The active matrix structure as claimed in claim 11 , wherein the storage capacitor bus (Rn) of a row (Rn) of rank n in the matrix is connected to a previous row selection line, the rank of said previous row being determined as a function of a mode of addressing of the display screen in which the matrix must operate.

13. The active matrix structure as claimed in claim 12 , wherein for a mode of addressing involving a line inversion, the storage capacitor bus of the row of rank n is connected to the selection line of the row of rank n- 2 .

14. The active matrix structure as claimed in claim 12 , wherein for a mode of addressing involving a double-line inversion, the storage capacitor bus of the row of rank n is connected to the selection line of the row of rank n- 4 .

15. The active matrix structure as claimed in claim 5 , for a transistor of type with a gate below, wherein the storage capacitor bus is produced on a level disposed above the levels of the selection lines and the data lines.

16. The active matrix structure as claimed in claim 5 , for a transistor of type with a gate above, wherein the storage capacitor bus is produced on a level disposed below the levels of the selection lines and the data lines, directly on a substrate, or on an optical mask level.

17. A display screen comprising an active matrix structure as claimed in claim 1 .

18. The display screen as claimed in claim 17 , wherein the switching devices are transistors, the selection line of a row forming gate for each of the transistors of the row, and wherein the row selection lines are driven by a line addressing signal of a pulse type having plural voltage levels.