Liquid crystal display device having a light-sensing thin film transistor disposed at a pixel region

1. A liquid crystal display device with sensing function comprising:

a gate line and a data line crossing each other on a substrate, so as to define a pixel region including a pixel electrode;

a first switching thin film transistor formed at a crossing of the gate and data lines;

a first driving voltage supplying line and a second driving voltage supplying line being parallel to the gate line,

a sensing thin film transistor, formed at a predetermined portion of the pixel region and connected to a driving voltage supplying line, for sensing external light;

a sensing storage capacitor for storing a signal sensed by the sensing thin film transistor; a second switching thin film transistor for receiving the sensing signal stored and reading externally inputted information,

a read-out line being parallel to the data line and connected to the second switching thin film transistor,

a first passivation film formed on the sensing storage capacitor and the second switching thin film transistor;

a reflective electrode formed on the first passivation film and overlapping the sensing storage capacitor and the second switching thin film transistor so as to provide a reflective region, and

a second passivation film formed between the reflective electrode and the pixel electrode,

wherein the sensing thin film transistor, the sensing storage capacitor and the second switching thin film transistor are formed into an in-line type and adjacent to the read-out line,

wherein the pixel electrode overlaps the sensing storage capacitor and wherein the first passivation film, the reflective electrode and the second passivation film are formed between the sensing storage capacitor and the pixel electrode, and

wherein the first passivation film is removed on the sensing thin film transistor and the second passivation film contacts with the sensing thin film transistor, wherein the first passivation film is thicker than the second passivation film.

2. The device of claim 1 , wherein the sensing thin film transistor comprises:

a gate electrode connected to the first driving voltage supplying line supplied with a first driving voltage;

a driving source electrode connected to the second driving voltage supplying line supplied with a second driving voltage;

a driving drain electrode positioned opposite to the driving source electrode; and

a semiconductor layer formed between the gate electrode and the driving source electrode or between the gate electrode and the driving drain electrode.

3. The device of claim 1 , wherein the sensing storage capacitor comprises:

a storage capacitor lower electrode connected to the gate electrode of the sensing thin film transistor and being parallel to the read-out line; and

a storage capacitor upper electrode overlapping the storage capacitor lower electrode with an insulation film therebetween, and connected to the driving drain electrode of the sensing thin film transistor, and being parallel to the lead-out line.

4. The device of claim 3 , wherein the second switching thin film transistor comprises:

a gate electrode connected to the gate line;

a source electrode connected to the storage capacitor upper electrode;

a drain electrode positioned opposite to the source electrode and connected to the read-out line; and

a semiconductor layer formed between the gate electrode and the source electrode or between the gate electrode and the drain electrode.

5. The device of claim 4 , wherein the storage capacitor lower electrode is extended from the gate electrode of the sensing thin film transistor and the storage capacitor upper electrode extended from the driving drain electrode of the sensing thin film transistor.

6. The device of claim 1 , wherein the sensing storage capacitor is formed on the right side of the pixel region.