Liquid crystal display device and fabricating method and driving method thereof

• US 20070296685A1
• Filed: 12/12/2006
• Published: 12/27/2007
• Est. Priority Date: 06/23/2006
• Status: Active Grant

• Current Assignee: LG Display Co., Ltd.
• Original Assignee: LG Display Co., Ltd.
• Inventors: Kang, Hee Kwang, Choo, Kyo Seop
• Granted Patent: US 8,624,821 B2
• Time in Patent Office: Days
• US Class Current: 345/102
• CPC Class Codes: G02F 1/13312 Circuits comprising photodetectors for purposes other than feedback
• CPC Class Codes: G02F 1/13318 Circuits comprising a photodetector
• CPC Class Codes: G09G 2320/0633 by amplitude modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix

Abstract

Disclosed is a liquid crystal display device, a fabricating method, and a driving method thereof that includes at least one integrated photosensor that senses external light illumination on the liquid crystal display device. A sensing signal from the at least one photosensors are converted into a digital signal that is stored to represent an external illumination distribution. The liquid crystal display device includes a backlight that has a plurality of light sources that may be independently driven. A controller generates a control signal that independently drives the light sources in a manner corresponding to the illumination distribution. In doing so, areas of the liquid crystal display device may be provided with a greater amount of light from a corresponding light source so that externally illuminated areas of the liquid crystal display device do not suffer from reduced contrast.

Claims

1. A liquid crystal display device comprising:

a plurality of photo sensing devices formed on a TFT array substrate that sense an external light irradiated into a liquid crystal display panel;

an integrated circuit portion that reads out signals corresponding to an illumination distribution by the external light in accordance with a sensing result by each of the photo sensing devices;

a backlight having a plurality of light sources that independently supply light to the liquid crystal display panel in accordance with the illumination distribution; and

a backlight driver that drives the backlight.

2. The liquid crystal display device as claimed in claim 1, further comprising:

an analog-digital converter that converts an analog signal from each of the photo sensing devices into a digital signal;

a memory that stores an illumination distribution data corresponding to the digital signals from the analog-digital converter; and

a timing controller that generates a control signal for controlling the plurality of light sources based on the illumination distribution data and supplies the control signal to the backlight driver.

3. The liquid crystal display device as claimed in claim 2, wherein the backlight driver includes:

a plurality of inverter circuit portions that supply an independent driving voltage to each of the plurality of light sources; and

an inverter controller that controls the inverter circuit portions using the control signal.

4. The liquid crystal display device as claimed in claim 1, wherein the liquid crystal display panel further includes:

a color filter array substrate joined to the TFT array substrate; and

a liquid crystal between the color filter array substrate and the TFT array substrate.

5. The liquid crystal display device as claimed in claim 1, wherein the TFT array substrate includes:

a gate line and a data line formed that cross each other to define a pixel area;

a first thin film transistor provided at a crossing of the gate line and the data line;

a pixel electrode connected to the first thin film transistor and positioned at a pixel area; and

a first storage capacitor that stores a pixel voltage charged into the pixel electrode.

6. The liquid crystal display device as claimed in claim 5, wherein the photo sensing device includes:

a sensor thin film transistor that senses an external light;

a first driving voltage supply line that supplies a first driving voltage to the sensor thin film transistor;

a second driving voltage supply line that supplies a second driving voltage to the sensor thin film transistor;

a second storage capacitor that stores a signal voltage sensed by the sensor thin film transistor;

a second thin film transistor positioned between the first storage capacitor and the integrated circuit portion that supplies the sensing signal to the integrated circuit; and

a sensing signal transmission line that transmits the sensing signal from the second thin film transistor to the integrated circuit portion.

7. The liquid crystal display device as claimed in claim 6, wherein the sensor thin film transistor includes:

a first gate electrode formed on a substrate and connected to the second driving voltage supply line;

a gate insulating film that covers the first gate electrode;

a first semiconductor pattern overlapping the first gate electrode with the gate insulating film between them;

a first source electrode electrically connected to the first semiconductor pattern and electrically connected to the first driving voltage supply line; and

a first drain electrode opposed to the first source electrode.

8. The liquid crystal display device as claimed in claim 7, further including:

a protective film that covers the sensor thin film transistor;

a first hole passing through the protective film and the gate insulating film to expose the first driving voltage supply line; and

a transparent electrode pattern formed to cover the first hole, and

wherein the first source electrode and the first driving voltage supply line are electrically connected to each other by the transparent electrode pattern.

9. The liquid crystal display device as claimed in claim 7, wherein the first storage capacitor includes:

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

a first upper storage electrode overlapped with the first lower storage electrode and connected to the first drain electrode with the gate insulating film between them.

10. The liquid crystal display device as claimed in claim 7, wherein the second thin film transistor includes:

a second gate electrode extended from the gate line;

a second semiconductor pattern overlapped with the second gate electrode with the gate insulating film between them;

a second source electrode electrically connected to the second semiconductor pattern; and

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

11. The liquid crystal display device as claimed in claim 7, wherein the first thin film transistor includes:

a third gate electrode extended from the gate line;

a third semiconductor pattern that overlaps the third gate electrode with the gate insulating film between them;

a third source electrode electrically connected to the third semiconductor pattern and extended from the data line; and

a third drain electrode connected to the pixel electrode.

12. The liquid crystal display device as claimed in claim 1, further including:

a gate driver that supplies a gate signal to a gate line of the liquid crystal display panel; and

a data driver that supplies a data signal to a data line of the liquid crystal display panel.

13. The liquid crystal display device as claimed in claim 1, wherein the light sources are arranged in a matrix at a rear side of the liquid crystal display panel.

14. A method of driving a liquid crystal display device, comprising:

sensing an external light irradiated onto a liquid crystal display panel using a photo sensing device provided within the liquid crystal display device;

measuring an illumination distribution corresponding to the external light in accordance with a result of the sensing by the photo sensing device; and

adjusting a light amount supplied to the liquid crystal display panel in accordance with the illumination distribution.

15. The method of driving the liquid crystal display device as claimed in claim 14, wherein adjusting the light amount in accordance with the illumination distribution includes:

converting a signal sensed by the photo sensing device into a digital signal;

providing an illumination distribution data corresponding to the digital signal; and

providing a control signal that corresponds to the illumination distribution data; and

selectively adjusting the light amount from each of the plurality of light sources according to the control signal.

16. The method of driving the liquid crystal display device as claimed in claim 15, wherein selectively adjusting the light amount includes:

supplying a first amount of light to an area where the external light is irradiated onto the liquid crystal display panel; and

supplying a second amount of light to an area other than an area where the external light is irradiated.

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

forming a liquid crystal display panel that includes a plurality of photo sensing devices that sense an external light;

preparing an integrated circuit portion that reads out a signal corresponding to illumination distribution, wherein the illumination distribution corresponds to a sensing result by the photo sensing devices; and

preparing a plurality light sources that independently supply light to the liquid crystal display panel in accordance with the illumination distribution,

wherein forming the liquid crystal display panel includes forming a thin film transistor array substrate including the photo sensing device, forming a color filter array substrate, and joining the thin film transistor array substrate with the color filter array substrate.

18. The method of fabricating the liquid crystal display device as claimed in claim 17, wherein forming a thin film transistor array substrate including the photo sensing device includes:

forming a gate pattern having a gate line, a first gate electrode of a sensor thin film transistor, a second gate electrode of a first thin film transistor and a third gate electrode of a second thin film transistor on a substrate;

forming a gate insulating film on the substrate;

forming a first semiconductor pattern that overlaps the first gate electrode, a second semiconductor pattern overlapped with the second gate electrode and a third semiconductor pattern overlapped with the third gate electrode on the gate insulating film;

forming a source/drain pattern having a data line that crosses the gate line, a first source electrode and a first drain electrode connected to a first semiconductor pattern, respectively, a second source electrode and a second drain electrode connected to a second semiconductor pattern, respectively, and a third source electrode and a third drain electrode connected to a third semiconductor pattern, respectively, thereby forming a first thin film transistor and a photo sensing device having the sensor thin film transistor and the second thin film transistor;

forming a protective film having a first hole that exposes a second drain electrode of the first thin film transistor; and

forming a pixel electrode connected to the second drain electrode via the first hole.

19. The method of fabricating the liquid crystal display device as claimed in claim 18, wherein forming the gate pattern includes:

forming a first driving voltage supply line, a second driving voltage supply line connected to the first gate electrode and a first lower storage electrode parallel to the gate line and extended from the second driving voltage supply line.

20. The method of fabricating the liquid crystal display device as claimed in claim 19, wherein forming the source/drain pattern includes:

forming a first upper storage electrode that overlaps the first lower storage electrode with the gate insulating film between them, thereby forming a first storage capacitor.

21. The method of fabricating the liquid crystal display device as claimed in claim 20, further including forming a second storage capacitor, wherein forming the second storage capacitor includes:

forming a first storage sub-capacitor having a second storage electrode positioned between a first drain electrode of the sensor thin film transistor and a second source electrode of the second thin film transistor, and the second driving voltage supply line overlapped with the second storage electrode with the gate insulating film between them;

forming a second storage sub-capacitor having the second storage electrode, and the first driving voltage supply line overlapped with the second storage electrode with the gate insulating film between them; and

forming a third storage sub-capacitor having the second storage electrode, and a second transparent electrode pattern connected, via a second hole overlapped with the second storage electrode and exposing the second driving voltage supply line with having a protective film therebetween, with second driving voltage supply line.

22. The method of fabricating the liquid crystal display device as claimed in claim 18, wherein forming the pixel electrode further includes forming a first transparent electrode pattern connected to the first driving voltage supply line via a third hole passing through the gate insulating film and the protective film, and connected to the first source electrode of the sensing thin film transistor via a fourth hole passing through the protective film.

23. The method of fabricating the liquid crystal display device as claimed in claim 18, wherein forming the source/drain pattern includes forming a sensing signal transmission line that is connected to a third drain electrode of the second thin film transistor.