EL display device and electronic apparatus

• US 6,680,577 B1
• Filed: 11/17/2000
• Issued: 01/20/2004
• Est. Priority Date: 11/29/1999
• Status: Expired due to Term

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Koyama, Jun, Inukai, Kazutaka
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): A, Minh D
• Application Number:
  US09/715,528
• Time in Patent Office: 1,159 Days
• Field of Search: 315/169.1, 315/169.3, 313/397, 313/400, 313/503, 313/517, 257/52, 257/59, 257/72, 257/296, 257/344, 257/366
• US Class Current: 315/169.3
• CPC Class Codes: G09G 2300/0426 Layout of electrodes and connections
• CPC Class Codes: G09G 2300/0465 Improved aperture ratio, e.g. by size reduction of the pixel circuit, e.g. for improving the pixel density or the maximum displayable luminance or brightness
• CPC Class Codes: G09G 2300/0842 forming a memory circuit, e.g. a dynamic memory with one capacitor
• CPC Class Codes: G09G 2300/0847 being a dynamic memory without any storage capacitor, i.e. with use of parasitic capacitances as storage elements
• CPC Class Codes: G09G 2300/0866 by means of changes in the pixel supply voltage
• CPC Class Codes: G09G 2310/0283 Arrangement of drivers for different directions of scanning
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 3/2011 by amplitude modulation
• 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 3/3258 with pixel circuitry controlling the voltage across the light-emitting element
• CPC Class Codes: G09G 3/3266 Details of drivers for scan electrodes
• CPC Class Codes: G09G 3/3275 Details of drivers for data electrodes
• CPC Class Codes: G09G 3/3291 in which the data driver supplies a variable data voltage for setting the current through, or the voltage across, the light-emitting elements
• CPC Class Codes: H01L 27/1214 comprising a plurality of TFTs formed on a non-semiconducting substrate, e.g. driving circuits for AMLCDs
• CPC Class Codes: H01L 27/1222 with a particular composition, shape or crystalline structure of the active layer
• 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 29/78645 : with multiple gate
• CPC Class Codes: H04M 1/22 : Illumination; Arrangements for improving the visibility of characters on dials
• CPC Class Codes: H10K 59/12 : Active-matrix OLED [AMOLED] displays
• CPC Class Codes: H10K 59/1213 : the pixel elements being TFTs

Abstract

An EL display device capable of clear, multi-gradation color display, and an electronic device having the EL display device, are provided. Gradation display is performed in accordance with a time division driver method which controls by the amount of time an EL element formed in a pixel emits light, and the amount of time it does not emit light. Influence due to dispersion in the characteristics of electric current TFTs is prevented.

Claims

1. An EL display device having a pixel portion over a substrate, said pixel portion comprising:

a switching TFT having a LDD region in contact with a channel region and not overlapping a gate electrode with a gate insulating film interposed therebetween; and

a current control TFT having the LDD region overlapping the gate electrode with the gate insulating film interposed therebetween.

2. An EL display device according to claim 1, wherein said EL display device is incorporated into an electronic apparatus selected from the group consisting of video camera, a digital camera, a goggle type display device, a navigation system, a an audio playback device, a notebook type personal computer, a game apparatus, a portable information terminal and an image playback device.

3. An EL display device according to claim 1, wherein said EL display device is operated by a time-divisional gradation method.

4. An EL display device having a pixel portion, a source driver circuit and a gate driver circuit over a substrate, said pixel portion comprising:

a switching TFT having a LDD region in contact with a channel region and not overlapping a gate electrode with a gate insulating film interposed therebetween; and

a current control TFT having the LDD region overlapping the gate electrode with the gate insulating film interposed therebetween.

5. An EL display device according to claim 4, wherein said EL display device is incorporated into an electronic apparatus selected from the group consisting of a video camera, a digital camera, a goggle type display device, a navigation system, an audio playback device, a notebook type personal computer, a game apparatus, a portable information terminal and an image playback device.

6. An EL display device according to claim 4, wherein said EL display device is operated by a time-divisional graduation method.

7. An EL display device having a pixel portion over a substrate, said pixel portion comprising:

a switching TFT having a LDD region in contact with a channel region and not overlapping a gate electrode with a gate insulating film interposed therebetween; and

a current control TFT having the LDD region overlapping the gate electrode with the gate insulating film interposed therebetween,

wherein said switching TFT comprises any one of a p-channel TFT and a n-channel TFT,

wherein said current control TFT comprises the p-channel TFT, and

wherein a drain region of said current control TFT is electrically connected to an anode of an EL element.

8. An EL display device according to claim 7, wherein said EL display device is incorporated into an electronic apparatus selected from the group consisting of a video camera, a digital camera, a goggle type display device, a navigation system, an audio playback device, a notebook type personal computer, a game apparatus, a portable information terminal and an image playback device.

9. An EL display device according to claim 7, wherein said EL display device is operated by a time-divisional graduation method.

10. An EL display device having a pixel portion, a source driver circuit and a gate driver circuit over a substrate, said pixel portion comprising:

a switching TFT having a LDD region in contact with a channel region and not overlapping a gate electrode with a gate insulating film interposed therebetween; and

a current control TFT having the LDD region overlapping the gate electrode with the gate insulating film interposed therebetween,

wherein said switching TFT comprises any one of a p-channel TFT and a n-channel TFT,

wherein said current control TFT comprises the p-channel TFT, and

wherein a drain region of said current control TFT is electrically connected to an anode of an EL element.

11. An EL display device according to claim 10, wherein said EL display device is incorporated into an electronic apparatus selected from the group consisting of a video camera, a digital camera, a goggle type display device, a navigation system, an audio playback device, a notebook type personal computer, a game apparatus, a portable information terminal and an image playback device.

12. An EL display device according to claim 10, wherein said EL display device is operated by a time-divisional graduation method.

13. An EL display device having a pixel portion over a substrate, said pixel portion comprising:

a switching TFT having a LDD region in contact with a channel region and not overlapping a gate electrode with a gate insulating film interposed therebetween; and

a current control TFT having the LDD region overlapping the gate electrode with the gate insulating film interposed therebetween,

wherein said switching TFT comprises any one of a p-channel TFT and a n-channel TFT,

wherein said current control TFT comprises the p-channel TFT, and

wherein a drain region of said current control TFT is electrically connected to a cathode of an EL element.

14. An EL display device according to claim 13, wherein said EL display device is incorporated into an electronic apparatus selected from the group consisting of a video camera, a digital camera, a goggle type display device, a navigation system, an audio playback device, a notebook type personal computer, a game apparatus, a portable information terminal and an image playback device.

15. An EL display device according to claim 13, wherein said EL display device is operated by a time-divisional graduation method.

16. An EL display device having a pixel portion, a source driver circuit and a gate driver circuit over a substrate, said pixel portion comprising:

a switching TFT having a LDD region in contact with a channel region and not overlapping a gate electrode with a gate insulating film interposed therebetween; and

a current control TFT having the LDD region overlapping the gate electrode with the gate insulating film interposed therebetween,

wherein said switching TFT comprises any one of a p-channel TFT and a n-channel TFT,

wherein said current control TFT comprises the p-channel TFT, and

wherein a drain region of said current control TFT is electrically connected to a cathode of an EL element.

17. An EL display device according to claim 16, wherein said EL display device is incorporated into an electronic apparatus selected from the group consisting of a video camera, a digital camera, a goggle type display device, a navigation system, an audio playback device, a notebook type personal computer, a game apparatus, a portable information terminal and an image playback device.

18. An EL display device according to claim 16, wherein said EL display device is operated by a time-divisional graduation method.