Liquid crystal display device capable of automatically switching to a mode and method for driving the same

1. A liquid crystal display device comprising:

a liquid crystal display panel including a first substrate having a display region and a non-display region, a liquid crystal layer, and a second substrate;

a backlight unit opposite a surface of the first substrate that illuminates light onto the liquid crystal display panel;

a plurality of gate lines arranged to cross a plurality of data lines on the first substrate;

a switching device formed in intersection portions of the gate lines and the data lines, wherein the switching device is driven by a signal applied through the gate line;

a plurality of first and second sensor lines substantially parallel to the data lines;

a plurality of first sensors at crossings of the gate lines and the first sensor lines in a first region of the display region of the first substrate to sense ambient light; and

a plurality of second sensors at crossings of the gate lines and the second sensor lines in a second region of the display region of the first substrate to sense light from the backlight unit,

wherein the first sensors and the second sensors are formed on the gate line that is connected to the switching device, and

wherein a black matrix blocking light is formed on the second substrate to exclude a portion of the second substrate that corresponds to the first sensors to allow ambient light to be incident on the first sensors,

wherein each of the first and second sensors includes a gate electrode, a semiconductor layer formed on the gate electrode wherein a current flow amount changes according to intensity of light illuminated thereon and source and drain electrodes formed on the semiconductor layer,

wherein a portion of a gate electrode of the second sensor includes an opening to expose the second sensor to light from the backlight unit, and

wherein the semiconductor layer of the second sensor directly contacts the first substrate and the gate electrode in the opening.

2. The liquid crystal display device according to claim 1 , further comprising:

a comparing unit that generates a comparison result based on a comparison of an output signal of the first sensor and an output signal of the second sensor; and

a control unit that controls the backlight unit according to the comparison result.

3. The liquid crystal display device according to claim 2 , wherein the control unit suspends an operation of the backlight unit when the output signal of the first sensor is greater than the output signal of the second sensor.

4. The liquid crystal display device according to claim 2 , wherein the control unit operates the backlight unit when the output signal of the first sensor is smaller than the output signal of the second sensor.

5. The liquid crystal display device according to claim 2 , further comprising a first sensor output line that connects the first sensor lines to the comparing unit.

6. The liquid crystal display device according to claim 2 , further comprising a second sensor output line that connects the second sensor lines to the comparing unit.

7. The liquid crystal display device according to claim 1 , wherein each first sensor includes a gate electrode that blocks light emitted by the backlight unit from being incident on the first sensor.

8. The liquid crystal display device according to claim 1 , further including a black matrix portion corresponding to each of the second sensors that blocks ambient light from falling incident on the second sensors.

9. A method for driving a liquid crystal display device including a liquid crystal display panel including: a first substrate having a display region and a non-display region, and a second substrate; a backlight unit opposite a surface of the first substrate that illuminates light; a plurality of gate lines and data lines arranged to intersect on the first substrate; a switching device formed in intersection portions where the gate lines and the data lines, wherein the switching device is driven by a signal applied through the gate line; a plurality of first and second sensor lines arranged in parallel to the data lines; a plurality of first sensors on crossings of the gate lines and the first sensor lines in a first region of the first substrate; a plurality of second sensors on crossings of the gate lines and the second sensor lines in a second region of the first substrate; a comparing unit connected to the first and second sensor lines; and a control unit connected between the comparing unit and the backlight unit comprising:

sensing ambient light using the first sensors at the crossings of the gate lines and the first sensor lines in the first region of the display region of the first substrate;

sensing light from the backlight unit using the second sensors at the crossings of the gate lines and the second sensor lines in the second region of the display region of the first substrate; and

comparing an intensity of ambient light with an intensity of light from the backlight unit to control the backlight unit,

wherein the first sensors and the second sensors are formed on the gate line that is connected to the switching device, and

wherein a black matrix blocking light is formed on the second substrate to exclude a portion of the second substrate that corresponds to the first sensors to allow ambient light external to the liquid crystal display device to be incident on the first sensors,

wherein each of the first and second sensors includes a gate electrode, a semiconductor layer formed on the gate electrode and whose current amount changes according to intensity of light illuminated thereon, and source and drain electrodes formed on the semiconductor layer, and

wherein the gate electrode of each second sensor includes an opening that exposes the second sensor to light from the backlight unit, and

wherein the semiconductor layer of the second sensor directly contacts the first substrate and the gate electrode in the opening.

10. The method according to claim 9 , further comprising:

providing a first signal corresponding to the sensed ambient light via the first sensor line to the comparing unit;

providing a second signal corresponding to the sensed light from the backlight unit via the second sensor line to the comparing unit;

generating a comparison result by comparing the first signal and the second signal using the comparing unit; and

controlling the backlight unit according to the comparison result using the control unit.

11. The method according to claim 10 , wherein controlling the backlight unit according to the comparison result using the control unit includes suspending an operation of the backlight unit when the output of the first sensor is greater than the output of the second sensor.

12. The method according to claim 10 , wherein controlling the backlight unit according to the comparison results using the control unit includes maintaining an operation of the backlight unit when the output of the first sensor is smaller than the output of the second sensor.

13. The method according to claim 9 , wherein the gate electrode of each first sensor blocks light emitted by the backlight unit from being incident on the respective first sensor.

14. The method according to claim 9 , wherein a black matrix that blocks light is formed on the second substrate having a portion corresponding to the second sensors to prevent ambient light external to the liquid crystal display device from falling incident on the second sensors.