US 7,002,181 B2 · Thin film transistor and use of same

Abstract

Disclosed are a thin film transistor capable of controlling gray level of an organic LED element by discretely controlling current levels, a method of manufacturing the thin film transistor, an array substrate including the thin film transistor, a display device, and a method of driving the display device. The thin film transistor includes an active layer formed on an insulating substrate, a plurality of insulating layers formed oppositely to each other with the active layer interposed therebetween, a first gate electrode and a second gate electrode formed adjacently to the insulating layers, respectively, and wiring connected to the first and second gate electrodes, respectively, the wiring controlling respective potentials of the first and second gate electrodes independently of each other. The area of the first gate electrode is different from the area of the second gate electrode, and current levels can be discretely controlled in at least four levels.

Drawings

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Drawings

Claims8

Dependent claims

A displayed device, comprising:

an organic LED element which is part of a pixel in an array of a plurality of pixels;
a switching thin film transistor electrically connected to at least one of said elements;
a driver thin film transistor electrically connected to said at least one of said elements, and wherein said driver thin film transistor further comprises:
a first insulating film having a first and a second surface;
an active layer positioned on a portion of said first surface of said first insulating film;
a second insulating film positioned on said active layer and on said first surface of said first insulating film;
a first gate electrode having a first area positioned on said second surface of said first insulating film;
a second gate electrode positioned on said second insulating film, said second gate electrode having a second area less than or greater than said first area of said first gate electrode;
a first conductor connected to said first gate electrode for selectively applying a first voltage to said first gate electrode and operate said transistor in conjunction with or independent of said second gate electrode;
and
a second conductor connected to said second gate electrode for applying a second voltage to said second gate electrode and operate said transistor in conjunction with or independent of said first gate electrode.

8 more elements

Dependencies are inferred from the claim text.

Description5,487 words

Summary2,313 words

#The present invention relates to a thin film transistor including a so-called dual gate structure for driving the thin film transistor by using a plurality of gate electrodes and a method of manufacturing the thin film transistor. The present invention further relates to a display device including the thin film transistor, and a method of driving the display device.

#An organic LED (light emitting diode) has a very high response speed and is a self-emitting device, and thus, it is expected that the application of the organic LED to a display device will allow providing an excellent flat display device having a wide viewing angle. The application of the organic LED to the flat display device replaces a liquid crystal display device. The above-mentioned organic LED is a current-driven element and, thus, the achievement of high-resolution display requires a continuous feed of a current through the organic LED element even during non-selection of a scanning line.

#FIG. 9 is a diagram showing a circuit configuration for driving an organic LED, which has been heretofore proposed. The conventional circuit configuration shown in FIG. 9 includes a switching thin film transistor, hereinafter referred to as TFT 80, for generally performing switching, and a driver TFT 84 for driving an organic LED element 82. Switching TFT 80 is driven to be turned on and off in accordance with a signal supplied through a scan line 86 and, thus, supplies to driver TFT 84 a signal supplied through a signal line 88.

Brief description of the drawings12 figures

#FIG. 1 is a cross-sectional view in elevation showing a schematic configuration of the dual gate TFT of the present invention;

#FIG. 2 is a perspective view showing in detail the arrangement of a first gate electrode and a second gate electrode of the dual gate TFT of the present invention relative to a channel;

#FIG. 3 is a diagram showing a schematic circuit configuration of a transistor element and an organic LED element, which are formed in one pixel of a thin film transistor array substrate using the dual gate TFT of the present invention;

Detailed description2,805 words

#The present invention will be described in detail below with reference to an embodiment shown in the drawings. FIG. 1 is a cross-sectional view showing a schematic configuration of a dual gate TFT of the present invention. Dual gate TFT of the present invention includes a first gate electrode 12 formed on an insulating substrate 10 made of glass or the like, and a second gate electrode 14. Between first gate electrode 12 and second gate electrode 14, formed are: a first gate insulating film 16; an active layer 18; a source electrode 20 and a drain electrode 22 which are formed adjacently to the active layer and function to define a channel; and a second gate insulating film 24 for insulating the second gate electrode from a lower thin film transistor element.

#In the present invention, a channel length refers to the length of the active layer from the source electrode to the drain electrode, which is defined between the source electrode and the drain electrode. In the present invention, the ends of the channel refer to respective ends of the source and drain electrodes and the active layer.

#First gate insulating film 16 and second gate insulating film 24 may be made of the same material or different materials, and the materials therefor can be selected from materials such as SiOx, SiyNz and SixOyNz (herein, x, y and z represent any positive real number). The above-mentioned active layer 18 can be made of any known material, for example, a semiconductor such as amorphous silicon, polycrystalline silicon or single-crystal silicon.

Facts

Application

10/765,793Filed 27 Jan 2004 · division

Priority

JP 2001-24696316 Aug 2001

Published

US 2004/0222472 A111 Nov 2004

Granted

21 Feb 2006

Term ended

15 Aug 2022

Estimated · how

20 years from earliest known nonprovisional domestic filing plus recorded patent term adjustment. Maintenance-fee lapses, terminal disclaimers and statutory extensions have not been checked. The continuity chain may be incomplete; this is not an enforceability determination.

Classification17 codes

G09G 3/3233
Using an active matrix: with pixel circuitry controlling the current through the light-emitting element
H10D 30/0321
Of thin-film transistors [TFT]: comprising silicon, e.g. amorphous silicon or polysilicon
H10D 30/0323
Comprising silicon, e.g. amorphous silicon or polysilicon: comprising monocrystalline silicon
H10D 30/6734
Multi-gate TFTs: having gate electrodes arranged on both top and bottom sides of the channel, e.g. dual-gate TFTs

Timeline

16 Aug 2001Priority claimedJP 2001-246963
27 Jan 2004Application filedUS 10/765,793
11 Nov 2004PublishedUS 2004/0222472 A1
18 Jul 2005Assigned to Toppoly Optoelectronics Corporationassignment of assignor's interest
21 Feb 2006GrantedUS 7,002,181 B2
23 Jan 2011Assigned to Tpo Displays Corp.change of name
8 Mar 2011Assigned to Chimei Innolux Corporationmerger
3 Apr 2014Assigned to Innolux Corporationchange of name
15 Aug 2022Term endedEstimated

Thin film transistor and use of same

Life of this patent

Thin film transistor and use of same

Life of this patent

Life of this patent

Abstract

Drawings

Drawings

Claims8

Description5,487 words

Drawings

Classification17 codes

Life of this patent

Description5,487 words