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

• US 20050073241A1
• Filed: 11/04/2004
• Published: 04/07/2005
• Est. Priority Date: 06/21/1999
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Fukunaga, Takeshi, Yamauchi, Yukio
• Granted Patent: US 7,312,572 B2
• Time in Patent Office: Days
• US Class Current: 313/497
• 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. An EL display device comprising:

a switching TFT and a current-control TFT formed over a substrate;

an insulating film formed over the switching TFT; and

an EL element formed over the current-control TFT and electrically connected thereto,

wherein an edge of the insulating film has a tapered shape,

wherein the edge of the insulating film is in contact with the EL element.

2. An EL display device according to claim 1, wherein the EL display device further comprises:

a first interlayer insulating film formed over the switching TFT; and

a second interlayer insulating film formed over the first interlayer insulating film,

wherein the insulating film is formed over the second insulating film.

3. An EL display device according to claim 1, wherein the EL display device further comprises a passivation film formed over the EL element.

4. An EL display device comprising:

a switching TFT and a current-control TFT formed over a substrate;

an insulating film formed over the switching TFT; and

an EL element formed over the current-control TFT and electrically connected thereto,

wherein the EL element comprises a first electrode, a second electrode and an EL layer interposed therebetween,

wherein an edge of the insulating film has a tapered shape,

wherein the edge of the insulating film is in contact with the first electrode and the EL layer.

5. An EL display device according to claim 4, wherein the EL display device further comprises:

a first interlayer insulating film formed over the switching TFT; and

a second interlayer insulating film formed over the first interlayer insulating film,

wherein the insulating film is formed over the second insulating film.

6. An EL display device according to claim 4, wherein the EL display device further comprises a passivation film formed over the EL element.

7. An electronic equipment having an EL display device, the EL display device comprising:

a switching TFT and a current-control TFT formed over a substrate;

an insulating film formed over the switching TFT; and

an EL element formed over the current-control TFT and electrically connected thereto,

wherein an edge of the insulating film has a tapered shape,

wherein the edge of the insulating film is in contact with the EL element.

8. An electronic equipment according to claim 7, wherein the EL display device further comprises:

a first interlayer insulating film formed over the switching TFT; and

a second interlayer insulating film formed over the first interlayer insulating film,

wherein the insulating film is formed over the second insulating film.

9. An electronic equipment according to claim 7, wherein the EL display device further comprises a passivation film formed over the EL element.

10. An electronic equipment according to claim 7, wherein the electronic equipment is selected from the group consisting of a personal computer, a video camera, a head mounted display, a picture reproducer and a portable computer.

11. An electronic equipment having an EL display device, the EL display device comprising:

a switching TFT and a current-control TFT formed over a substrate;

an insulating film formed over the switching TFT; and

an EL element formed over the current-control TFT and electrically connected thereto,

wherein the EL element comprises a first electrode, a second electrode and an EL layer interposed therebetween,

wherein an edge of the insulating film has a tapered shape,

wherein the edge of the insulating film is in contact with the first electrode and the EL layer.

12. An electronic equipment according to claim 11, wherein the EL display device further comprises:

a first interlayer insulating film formed over the switching TFT; and

a second interlayer insulating film formed over the first interlayer insulating film,

wherein the insulating film is formed over the second insulating film.

13. An electronic equipment according to claim 11, wherein the EL display device further comprises a passivation film formed over the EL element.

14. An electronic equipment according to claim 11, wherein the electronic equipment is selected from the group consisting of a personal computer, a video camera, a head mounted display, a picture reproducer and a portable computer.