Liquid crystal display device having image sensing function

• US 20060279690A1
• Filed: 08/19/2005
• Published: 12/14/2006
• Est. Priority Date: 06/09/2005
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Philips LCD Company Limited (LG Display Co., Ltd.)
• Inventors: Choo, Kyo Seop, Yu, Sang Hee, Han, Sang Chul, Kang, Hee Kwang
• Granted Patent: US 7,580,084 B2
• Time in Patent Office: Days
• US Class Current: 349/199
• 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: G02F 1/1362 Active matrix addressed cells G02F1/134336, G02F1/134363 take precedence
• CPC Class Codes: H04N 1/00127 Connection or combination of a still picture apparatus with another apparatus, e.g. for storage, processing or transmission of still picture signals or of information associated with a still picture
• CPC Class Codes: H04N 1/00129 with a display device, e.g. CRT or LCD monitor with a television apparatus H04N1/00283; arrangements for control of display devices G09G
• CPC Class Codes: H04N 1/195 the array comprising a two-dimensional array or a combination of two-dimensional arrays
• CPC Class Codes: H04N 2201/0081 Image reader H04N2201/0091 - H04N2201/0094 take precedence

Abstract

A liquid crystal display device includes a gate line and a data line intersecting each other on a substrate. The liquid crystal display device further includes a photo sensing device and a first thin film transistor (“TFT”) located at an intersection area of the gate line. The photo sensing device operates to sense an ambient light and includes a storage capacitor to store charge generated by light. The photo sensing device is drive by a driving voltage other than the data voltage.

Claims

1. A liquid crystal display device, comprising:

a data line supplying a data voltage;

a gate line intersecting the data line;

a first thin film transistor (“

TFT”

) located at an intersection area of the gate line and the data line; and

a photo sensing device operable to sense light and comprising a storage capacitor operable to store charge generated by the light, wherein the photo sensing device is driven by a drive voltage other than the data voltage.

2. The liquid crystal display device according to claim 1, wherein the photo sensing device comprises:

a photo TFT; and

a second TFT selectively supplying a signal sensed by the photo TFT via the storage capacitor.

3. The liquid crystal display device according to claim 2, wherein the photo sensing device further comprises an integrated circuit receiving the sensed signal from the second TFT.

4. The liquid crystal display device according to claim 2, further comprising a first drive voltage supply line formed in parallel to the gate line to supply a first drive voltage to the photo TFT, wherein the drive voltage comprises the first drive voltage.

5. The liquid crystal display device according to claim 4, further comprising a second drive voltage supply line formed in parallel to the first drive voltage supply line to supply the drive voltage to the photo TFT, wherein the drive voltage comprises the second drive voltage.

6. The liquid crystal display device according to claim 5, wherein the first drive voltage is connected to a source of the photo TFT and the second drive voltage is connected to a gate of the photo TFT.

7. The liquid crystal display device according to claim 3, further comprising a sensing signal transmission line operable to transmit the sensed signal from the second TFT to the integrated circuit.

8. The liquid crystal display device according to claim 5, wherein the photo TFT comprises:

a first gate electrode connected to the second drive voltage supply line;

a first source electrode electrically connected to the first drive voltage supply line; and

a first drain electrode connected to the second TFT.

9. The liquid crystal display device according to claim 8, further comprising the first source electrode and the first drive voltage supply line electrically connected with a transparent electrode pattern.

10. The liquid crystal display device according to claim 8, wherein the storage capacitor comprises:

a first storage lower electrode connected to the first gate electrode;

a first storage upper electrode facing the first storage lower electrode and connected to the first drain electrode; and

a gate insulating film disposed between the first storage lower electrode and the first storage upper electrode.

11. The liquid crystal display device according to claim 10, wherein the second TFT comprises:

a second gate electrode extended from the gate line;

a second source electrode extended from the first storage upper electrode; and

a second drain electrode connected to the sensing signal transmission line.

12. The liquid crystal display device according to claim 11, further comprising another storage capacitor including a pixel electrode and a neighboring gate line from a previous stage.

13. The liquid crystal display device according to claim 2, further comprising:

a pixel area disposed at the intersection of the data line and the gate line;

a color filter array substrate including a color filter corresponding to the pixel area; and

a black matrix for masking an area except the photo TFT and the pixel area.

14. The liquid crystal display device according to claim 1, wherein the liquid crystal display device comprises red, green and blue pixels and the photo sensing device is disposed in at least one of the red, green or blue pixels.

15. A fabricating method of a liquid crystal display device, comprising:

forming a gate pattern on a substrate;

forming first, second and third semiconductor patterns over the gate pattern;

forming a first source/drain pattern, a second source/drain pattern, and a third source/drain pattern on the first, second and third semiconductor patterns wherein a photo TFT is formed with the first source/drain pattern, a pixel TFT is formed with the second source/drain pattern and a switching TFT is formed with the third source/drain pattern;

forming a passivation film to form a contact hole; and

forming a transparent electrode pattern which includes a pixel electrode.

16. The fabricating method according to claim 15, wherein forming the gate pattern further comprises:

forming a first drive voltage supply line to be in parallel to the gate line to supply a first drive voltage to the photo TFT;

forming a second drive voltage supply line to be connected to the gate electrode of the photo TFT and in parallel to the first drive voltage supply line; and

forming a first storage lower electrode to be in parallel to the data line and connected to the first gate electrode.

17. The fabricating method according to claim 16, further comprising:

forming a first storage upper electrode to overlap the first storage lower electrode with a gate insulating film interposed therebetween wherein the first storage upper electrode forms a first storage capacitor along with the first storage lower electrode.

18. The fabricating method according to claim 16, wherein forming the passivation film comprises:

forming another contact hole that exposes the first drive voltage supply line and a first source pattern of the first source/drain pattern of the photo TFT by penetrating the gate insulating film and the passivation film.

19. The fabricating method according to claim 18, further comprising:

forming a transparent electrode electrically connecting the photo TFT and the first drive voltage supply line through the another contact hole.

20. An image sensing method of a liquid crystal display device, comprising:

irradiating a photo sensing device that is integrated within the liquid crystal display device with light having designated image information;

converting the light into a designated signal; and

detecting the image information based on the converted signal.

21. The image sensing method according to claim 20, wherein detecting the image information comprises forming the image information with light reflected from an object located adjacent the liquid crystal display device, the object comprising at least one of a human hand or a touch pen.

22. The image sensing method according to claim 20, wherein detecting the image information comprises detecting the image information in an area blocked by the object and an open area.

23. The image sensing method according to claim 20, further comprising forming the image information with at least one of an ambient light or light from a light pen.

24. The image sensing method according to claim 20, wherein detecting the image information comprises detecting brightness and darkness of a printed matter based light reflected from the printed matter.

25. The image sensing method according to claim 20, wherein detecting the image information further comprises detecting the image information in accordance with the intensity of light which is reflected from a bright area and the intensity of light which is reflected from a dark area.

26. The image sensing method according to claim 20, wherein the irradiating the photo sensing device comprises supplying the light from a backlight of the liquid crystal display device.

27. The image sensing method according to claim 20, wherein detecting the image information comprises:

storing the converted signal; and

supplying the stored converted signal to a signal detection circuit.