Liquid crystal display device performing both image display mode and fingerprint recognition mode

• US 20030174256A1
• Filed: 12/30/2002
• Published: 09/18/2003
• Est. Priority Date: 03/12/2002
• Status: Active Grant

• Current Assignee: Hydis Technology Company Limited (E Ink Holdings Incorporated)
• Original Assignee: Hydis Technology Company Limited (E Ink Holdings Incorporated)
• Inventors: Park, Kyu Chang, Kim, Choong Hoo, Shim, Min Soo
• Granted Patent: US 7,508,962 B2
• Time in Patent Office: Days
• US Class Current: 349/1
• CPC Class Codes: G02F 1/13312 Circuits comprising photodetectors for purposes other than feedback
• CPC Class Codes: G02F 1/13338 Input devices, e.g. touch panels
• CPC Class Codes: G06V 40/1318 using electro-optical elements or layers, e.g. electroluminescent sensing

Abstract

Disclosed is a liquid crystal display device. The device comprises a scan drive unit for selectively outputting turn-on/turn-off signals in the image display mode and outputting turn-on signals in the fingerprint recognition mode; a data drive unit for outputting data signals in the image display mode; a switch control unit for outputting turn-off signals in the image display mode and for selectively outputting turn-on/turn-off signals in the fingerprint recognition mode; a reading unit for outputting fingerprint image information read in the fingerprint recognition mode; a sensor thin film transistor for driving liquid crystal in the image display mode; and a switch thin film transistor having a channel with a first end and a second end, a drain and a source.

Claims

1. A liquid crystal display device, which performs both image display mode and fingerprint recognition mode, wherein the liquid crystal display device comprises:

a scan drive unit which selectively outputs one or more turn-on/turn-off signals to a corresponding row in the image display mode and which outputs one or more turn-on signals in the fingerprint recognition mode;

a data drive unit which outputs one or more data signals in the image display mode;

a switch control unit which outputs one or more turn-off signals in the image display mode and which selectively outputs turn-on/turn-off signals to a corresponding row in the fingerprint recognition mode;

a reading unit which outputs fingerprint image information read in the fingerprint recognition mode;

a sensor thin film transistor which drives liquid crystal in the image display mode, the sensor thin film transistor having a channel with a first end and a second, a drain and a source and, in which the first end of the channel is connected to an output terminal of the data drive unit, a photosensitive layer is formed between the drain and the source of the sensor thin film transistor, and the drain and the source become electrically conductive when light exceeding a predetermined amount of light is incident into the photosensitive layer; and

a switch thin film transistor having a channel with a first end and a second, a drain and a source, in which the first end of the channel of the switch thin film transistor is connected to the second end of the channel of the sensor thin film transistor, and the second end of the channel of the switch thin film transistor is connected to the input terminal of the reading unit.

2. The liquid crystal display device according to claim 1, wherein the switch thin film transistor is switched on for each frame in order to scan a fingerprint image.

3. The liquid crystal display device according to claim 1, wherein the second end of the channel of the sensor thin film transistor and the first end of the channel of the switch thin film transistor are connected to a transparent electrode.

4. The liquid crystal display device according to claim 1, wherein the sensor thin film transistor and the switch thin film transistor are formed on a transparent substrate, and the liquid crystal display device further comprises a light-emitting unit under the transparent substrate.

5. The liquid crystal display device according to claim 1, wherein the liquid crystal display device further comprises an electricity charging unit, one end of the charging unit being connected to the second end of the channel of the sensor thin film transistor and the other end of the charging unit being connected to the first end of the channel of the switch thin film transistor, and wherein electric charges generated from the sensor thin film transistors are accumulated in the electricity charging unit.

6. The liquid crystal display device according to claim 1, further comprising a light shut-off layer formed on the top of the switch thin film transistor.

7. A liquid crystal display device, which performs both image display mode and fingerprint recognition mode, wherein the liquid crystal display device comprises:

wherein the liquid crystal display device comprises;

a scan drive unit which selectively outputs one or more turn-on/turn-off signals to a corresponding row in the image display mode and which outputs one or more turn-on signals in the fingerprint recognition mode;

a data drive unit which outputs one or more data signals in the image display mode;

a switch control unit which outputs one or more turn-off signals in the image display mode and which selectively outputs turn-on/turn-off signals to a corresponding row in the fingerprint recognition mode;

a reading unit which outputs fingerprint image information read in the fingerprint recognition mode; and

a flat panel which displays images in the image display mode and receives fingerprint images in the fingerprint recognition mode,

wherein a part of the flat panel comprises;

a sensor thin film transistor which drives liquid crystal in the image display mode, the sensor thin film transistor having a channel with a first end and a second, a drain and a source and, in which the first end of the channel is connected to an output terminal of the data drive unit, a photosensitive layer is formed between the drain and the source of the sensor thin film transistor, and the drain and the source become electrically conductive when light exceeding a predetermined amount of light is incident into the photosensitive layer; and

a switch thin film transistor having a channel with a first end and a second, a drain and a source, in which the first end of the channel of the switch thin film transistor is connected to the second end of the channel of the sensor thin film transistor, and the second end of the channel of the switch thin film transistor is connected to the input terminal of the reading unit.