EL display device, driving method thereof, and electronic equipment provided with the EL display device

• US 8,405,594 B2
• Filed: 09/28/2010
• Issued: 03/26/2013
• Est. Priority Date: 06/21/1999
• Status: Expired due to Term

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Yamauchi, Yukio, Fukunaga, Takeshi
• Primary Examiner(s): Vo, Tuyet Thi
• Application Number:
  US12/892,277
• Publication Number:
  US 20110012818A1
• Time in Patent Office: 910 Days
• Field of Search: 345/74, 345/75, 345/76, 345/77, 345/82, 345/84, 345/88, 345/90, 345/92, 345/204, 345/211, 345/212, 345/214
• US Class Current: 345/92
• CPC Class Codes: G09G 2300/023 Display panel composed of stacked panels
• CPC Class Codes: G09G 2300/04 Structural and physical details of display devices
• CPC Class Codes: G09G 2300/0408 Integration of the drivers onto the display substrate
• CPC Class Codes: G09G 2300/0417 Special arrangements specific to the use of low carrier mobility technology
• CPC Class Codes: G09G 2300/0426 Layout of electrodes and connections
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 3/2018 by time modulation using two or more time intervals
• CPC Class Codes: G09G 3/2022 using sub-frames
• CPC Class Codes: G09G 3/30 using electroluminescent panels
• CPC Class Codes: G09G 3/32 semiconductive, e.g. using light-emitting diodes [LED]
• CPC Class Codes: G09G 3/3225 using an active matrix
• CPC Class Codes: G09G 3/3258 with pixel circuitry controlling the voltage across the light-emitting element
• CPC Class Codes: H01L 27/1277 using a crystallisation promoting species, e.g. local introduction of Ni catalyst
• CPC Class Codes: H01L 27/1296 adapted to increase the uniformity of device parameters
• CPC Class Codes: H01L 27/156 two-dimensional arrays
• CPC Class Codes: H01L 29/045 by their particular orientation of crystalline planes
• CPC Class Codes: H01L 29/0603 characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions isolation regions between components H01L21/76; design considerations for integrated circuits H01L27/00; geometrical design considerations for devices H01L29/0657
• CPC Class Codes: H01L 29/786 Thin film transistors, i.e. transistors with a channel being at least partly a thin film transistors having only the source or the drain region on an insulator layer H01L29/0653; thin film FinFETs H01L29/785
• CPC Class Codes: H01L 29/78621 with LDD structure or an extension or an offset region or characterised by the doping profile
• CPC Class Codes: H01L 29/78624 the source and the drain regions being asymmetrical
• CPC Class Codes: H01L 29/78627 : with a significant overlap between the lightly doped drain and the gate electrode, e.g. GOLDD
• CPC Class Codes: H01L 2924/00 : Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 : Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H01L 33/62 : Arrangements for conducting electric current to or from the semiconductor body, e.g. lead-frames, wire-bonds or solder balls
• CPC Class Codes: H10K 2102/3026 : Top emission
• CPC Class Codes: H10K 50/87 : Arrangements for heating or cooling
• CPC Class Codes: H10K 59/12 : Active-matrix OLED [AMOLED] displays
• CPC Class Codes: H10K 59/1213 : the pixel elements being TFTs
• CPC Class Codes: H10K 59/122 : Pixel-defining structures or layers, e.g. banks
• CPC Class Codes: H10K 59/8794 : Arrangements for heating and cooling

Abstract

An EL display device capable of performing clear multi-gradation color display and electronic equipment provided with the EL display device are provided, wherein gradation display is performed according to a time-division driving method in which the luminescence and non-luminescence of an EL element (109) disposed in a pixel (104) are controlled by time, and the influence by the characteristic variability of a current controlling TFT (108) is prevented. When this method is used, a data signal side driving circuit (102) and a gate signal side driving circuit (103) are formed with TFTs that use a silicon film having a peculiar crystal structure and exhibit an extremely high operation speed.

Claims

1. A light emitting element comprising:

an electrode formed of a conductive film over a substrate;

a transparent pixel electrode over and in contact with the electrode;

an insulating film over the transparent pixel electrode, the insulating film overlapping a part of the transparent pixel electrode;

an electroluminescent layer over the transparent pixel electrode and the insulating film; and

a cathode over the electroluminescent layer.

2. The light emitting element according to claim 1, wherein the transparent pixel electrode is an anode.

3. The light emitting element according to claim 1, wherein the cathode comprises magnesium and silver.

4. The light emitting element according to claim 1, wherein an edge portion of the insulating film has a taper shape.

5. The light emitting element according to claim 1, wherein the insulating film comprises an organic resin.

6. The light emitting element according to claim 1, further comprising a passivation film over the cathode, wherein the passivation film is an insulating film comprising silicon.

7. The light emitting element according to claim 1, wherein the electroluminescent layer emits white light.

8. The light emitting element according to claim 1, further comprising a switching element, wherein the electrode is electrically connected to the switching element.

9. The light emitting element according to claim 1, wherein the conductive film comprises aluminum.

10. A light emitting device comprising:

a pixel portion formed over a substrate;

plural pixels formed in the pixel portion;

a switching thin film transistor and a current-control thin film transistor formed in at least one of the plural pixels;

an electrode formed of a conductive film which is electrically connected to the current-control thin film transistor;

a transparent pixel electrode over and in contact with the electrode;

an insulating film over the transparent pixel electrode, the insulating film overlapping a part of the transparent pixel electrode;

an electroluminescent layer over and in contact with the transparent pixel electrode and the insulating film; and

a cathode over the electroluminescent layer,

wherein the conductive film comprises aluminum.

11. The light emitting device according to claim 10, wherein the transparent pixel electrode is an anode.

12. The light emitting device according to claim 10, wherein the cathode comprises magnesium and silver.

13. The light emitting device according to claim 10, wherein an edge portion of the insulating film has a taper shape.

14. The light emitting device according to claim 10, wherein the insulating film comprises an organic resin.

15. The light emitting device according to claim 10, further comprising a passivation film over the cathode, wherein the passivation film is an insulating film comprising silicon.

16. The light emitting device according to claim 10, wherein the electroluminescent layer emits white light.

17. The light emitting device according to claim 10, further comprising a color filter.

18. The light emitting device according to claim 10, wherein the conductive film comprises aluminum.

19. An electronic equipment comprising an electroluminescent element, the electroluminescent element comprising;

an electrode formed of a conductive film over a substrate;

a transparent pixel electrode over and in contact with the electrode;

an insulating film over the transparent pixel electrode, the insulating film overlapping a part of the transparent pixel electrode;

an electroluminescent layer over the transparent pixel electrode and the insulating film; and

a cathode over the electroluminescent layer,

wherein the conductive film comprises aluminum.

20. The electronic equipment according to claim 19, wherein the transparent pixel electrode is an anode.

21. The electronic equipment according to claim 19, wherein the cathode comprises magnesium and silver.

22. The electronic equipment according to claim 19, wherein an edge portion of the insulating film has a taper shape.

23. The electronic equipment according to claim 19, wherein the insulating film comprises an organic resin.

24. The electronic equipment according to claim 19, further comprising a passivation film over the cathode, wherein the passivation film is an insulating film comprising silicon.

25. The electronic equipment according to claim 19, wherein the electroluminescent layer emits white light.

26. The electronic equipment according to claim 19, further comprising a switching element, wherein the electrode is electrically connected to the switching element.

27. The electronic equipment according to claim 19, wherein the conductive film comprises aluminum.