Liquid crystal display device and fabricating method and driving method thereof

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.

This application claims the benefit of Korean Patent Application No. P2006-056744 filed in Korea on Jun. 23, 2006, which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a liquid crystal display device. More particularly, the invention relates to a liquid crystal display device, a fabricating method, and a driving method thereof that improve visibility and reduce power consumption as well as reduce fabricating costs.

2. Description of the Related Art

Generally, a liquid crystal display device LCD controls light transmittance of liquid crystal cells in accordance with video signals to display a picture. Such an LCD implementation typically includes an active matrix type LCD having a switching device for each cell. Such LCD display devices are used as computer monitors, office equipment, cellular phones and the like. The switching device for the active matrix LCD mainly employs an array of thin film transistors (hereinafter, referred to as “TFTs”).

FIG. 1illustrates a related art LCD driving apparatus.

Referring toFIG. 1, the related art LCD driving apparatus includes a liquid crystal display panel52having m×n liquid crystal cells Clc arranged in a matrix type, m data lines D1to Dm and n gate lines G1to Gn crossing each other and thin film transistors TFT provided at the crossings, a data driver64for applying data signals to the data lines D1to Dm of the liquid crystal display panel52, a gate driver66for applying scanning signals to the gate lines G1and Gn, a gamma voltage supplier68for supplying the data driver64with gamma voltages, a timing controller60for controlling the data driver64and the gate driver66using synchronizing signals from a system70, a direct current to direct current converter74(hereinafter a “DC/DC converter”) for generating voltages supplied to the liquid crystal display panel52using a voltage from a power supply62, and an inverter76for driving a back light78.

The system70applies vertical/horizontal synchronizing signals Vsync and Hsync, clock signals DCLK, a data enable signal DE, and R, G and B data signals to the timing controller60.

The liquid crystal display panel52includes a plurality of liquid crystal cells Clc arranged in a matrix at the crossings of the data lines D1to Dm and the gate lines G1to Gn. The thin film transistor TFT provided at each liquid crystal cell Clc applies a data signal from a corresponding data line D1to Dm to the liquid crystal cell Clc in response to a scanning signal from the gate line G. Further, each liquid crystal cell Clc is provided with a storage capacitor Cst. The storage capacitor Cst is provided between a pixel electrode of the liquid crystal cell Clc and a pre-stage gate line, or between the pixel electrode of the liquid crystal cell Clc and a common electrode line, to thereby maintain a constant voltage on the liquid crystal cell Clc.

The gamma voltage supplier68applies a plurality of gamma voltages to the data driver64.

The data driver64converts R, G, and B digital video data into analog gamma voltages (i.e., data signals) corresponding to gray level values in response to a control signal CS from the timing controller60, and applies the analog gamma voltages to the data lines D1to Dm.

The gate driver66sequentially applies a scanning pulse to the gate lines G1to Gn in response to a control signal CS from the timing controller60to thereby select horizontal lines of the liquid crystal display panel52supplied with the data signals from data driver64.

The timing controller60generates the control signals CS for controlling the gate driver66and the data driver64using the vertical/horizontal synchronizing signals Vsync and Hsync and the clock signal DCLK input from the system70. Herein, the control signal CS for controlling the gate driver66includes a gate start pulse GSP, a gate shift clock GSC and a gate output enable signal GOE, etc. Further, the control signal CS for controlling the data driver64includes a source start pulse SSP, a source shift clock SSC, a source output enable signal SOE, and a polarity signal POL, etc. The timing controller60re-aligns the R, D and B data from the system70to apply them to the data driver64.

The DC/DC converter74boosts or drops a 3.3V input voltage from the power supply62to generate a voltage supplied to the liquid crystal display panel52. Such a Dc/DC converter72generates a gamma reference voltage, a gate high voltage VGH, a gate low voltage VGL and a common voltage Vcom, etc.

The inverter76drives the backlight78with the aid of a driving voltage Vin supplied from any one of the power supply62and the system70. The backlight78is controlled by the inverter76to thereby generate a light and illuminate the liquid crystal display panel52.

A problem associated with the related art is that light output from the backlight78is constant. As such, if ambient light is greater than the panel brightness, panel visibility is reduced. Conversely, if the ambient light is low, then the panel may be overly bright in comparison. This excessive panel brightness in low ambient light conditions leads to unnecessary and excessive power consumption To solve this problem, a technique that senses an external light using a photosensor such as a photodiode, etc., and controls brightness of the backlight78by a user's operation in accordance with the photosensor output has been suggested. However, the addition of a separate photosensor increases assembly costs of the LCD panel.

Referring toFIG. 2, a technique that senses the external light53using a photosensor and controls brightness of the backlight in accordance with the result adjusts brightness of the backlight supplied to the entire liquid crystal display panel52. Such related art solutions cannot selectively increase brightness of the backlight at a specific area of the liquid crystal display panel52. Further, the external light53that illuminates a portion of the liquid crystal display panel52creates a problem in that the contrast ratio of the illuminated area (hereinafter, referred to as “illumination area”) P1, which is illuminated by the external light53, is reduced relative to the area (hereinafter, referred to as “non-illumination area”) P2, which is not illuminated the external light53.

SUMMARY OF THE INVENTION

The present invention provides a liquid crystal display device, fabricating method, and driving method thereof, that obviates one or more of the aforementioned problems due to limitations of the related art.

Accordingly, one advantage of the present invention is that it improves the contrast ratio of a liquid crystal display device under varying lighting conditions

Another advantage of the present invention is that it improves the uniformity of contrast of a liquid crystal display that is subject to uneven illumination by an external light source.

Still another advantage of the present invention is that it reduces the fabrication cost of a liquid crystal display that prevents a degradation of contrast under varying lighting conditions.

In order to achieve these and other objects of the invention, the present invention involves a liquid crystal display device having a TFT array substrate, which comprises a plurality of photo sensing devices formed on the TFT array substrate that sense an external light irradiated into the 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.

In another aspect of the present invention, the aforementioned and other advantages are achieved by a method of driving a liquid crystal display device, which comprises 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.

In another aspect of the present invention, the aforementioned and other advantages are achieved by a method of fabricating a liquid crystal display device, which comprises 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

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

FIG. 3is a block diagram schematically illustrating an exemplary a liquid crystal display device according to an embodiment of the present invention. In a liquid crystal display device illustrated inFIG. 3, at least one photosensor is formed along with thin film patterns of the thin film transistor array substrate of the liquid crystal display panel152. Accordingly, a separate external photodiode is not required. Here, the photosensor is directly formed within the liquid crystal display panel152to thereby improve accuracy of the sensor. Also, the amount of light produced by the backlight is selectively spatially increased only at an area of the liquid crystal display panel152that is illuminated by an external light source, as sensed by the photosensor, to thereby prevent a decrease in contrast for that illuminated area.

An exemplary configuration and an operation of the liquid crystal display device according to the present invention will be described with reference toFIG. 3toFIG. 5.

Referring toFIG. 3, a liquid crystal display device of the present invention includes a liquid crystal display device152, a data driver164for supplying a data signal to data lines DL1to DLm of the liquid crystal display device152, a gate driver166for supplying a scanning signal to gate lines GL1to GLn, a read-out integrated circuit portion202to which read-out lines RL1to RLm of the liquid crystal display panel152are connected, an analog-digital converter (hereinafter, referred to as “ADC”)220for converting an analog voltage from the read-out integrated circuit portion202into a digital signal, a gamma voltage supplier168for supplying a gamma voltage to the data driver164, a timing controller160for controlling the data driver164and the gate driver166using a synchronizing signal supplied from a system170, a memory206connected to the timing controller160, a DC/DC converter174for generating voltages supplied to the liquid crystal display panel152using a voltage supplied from a power supply162, a backlight212having light sources that are independently capable of being driven, and a backlight driver210for independently driving each of the light sources of the backlight212.

The system170applies vertical/horizontal synchronizing signals Vsync and Hsync, clock signals DCLK, a data enable signal DE, and R, G, B data to the timing controller160.

The liquid crystal display panel152is formed by joining a color filter array substrate including a thin film pattern such as a black matrix, a color filter, etc. to a thin film transistor array substrate including a thin film transistor array, etc., with a liquid crystal between the two substrates. The resulting structure has m×n liquid crystal cells arranged in a matrix.

FIG. 4is a plan view illustrating a thin film transistor array substrate190corresponding to any one of liquid crystal cells in the liquid crystal display panel152inFIG. 3.FIGS. 5A-Care sectional views of the thin film transistor array substrate taken along the I-I′, II-II′ and III-III′ lines inFIG. 4, respectively.

Referring to FIGS.4and5A-C, the thin film transistor array substrate190includes a gate line102and a data line104formed in such a manner to cross each other with having a gate insulating film144therebetween on a lower substrate142, and a pixel switching TFT (hereinafter, referred to as “first TFT”)106provided at each crossing of the gate line102and the data line104. The thin film transistor array substrate190further includes a pixel electrode118formed at a cell area between the data lines104and gate line102, a read-out line204formed parallel to the data line104with the pixel electrode118between them, and a first and second driving voltage supply line152and171formed parallel to the gate line102. Further included is a sensor TFT140positioned between the first and second driving voltage supply line152and171, wherein the sensor TFT140is supplied with a first and second driving voltage from the first and second driving voltage supply line152and171, respectively. Further included is a switching TFT (hereinafter “second TFT”)170formed at a crossing of the gate line102and the read-out line204, a pixel data storage capacitor (hereinafter “first storage capacitor”)120formed at an overlapping portion of the second driving voltage supply line171and the pixel electrode118, and a sensing signal storage capacitor (hereinafter “second storage capacitor”)180positioned between the second TFT170and the sensor TFT140.

The first TFT106includes a gate electrode108aconnected to the gate line102, a source electrode110aconnected to the data line104, a drain electrode112aconnected to the pixel electrode118, and an active layer114aoverlapped with the gate electrode108a, whereby a channel is formed between the source electrode110aand the drain electrode112a. The active layer114ais formed in such a manner to partially overlap the source electrode110aand the drain electrode112aand further includes a channel portion between the source electrode110aand the drain electrode112a. An ohmic contact layer148afor making ohmic contact with the source electrode110aand the drain electrode112ais further formed on the active layer114a. Herein, the active layer114aand the ohmic contact layer148amay be referred to as a semiconductor pattern145a.

The first TFT106allows a pixel voltage applied to the data line104to be charged into the pixel electrode118and maintained in response to a gate signal applied to the gate line102.

The pixel electrode118is connected, via a first contact hole115apassing through a protective film150, to the drain electrode112aof the TFT106. The pixel electrode118generates a potential difference with respect to a common electrode due to the charged pixel voltage. The common electrode may be provided at an upper substrate (not shown), such as a color filter array substrate. This potential difference rotates the liquid crystal molecules positioned between the thin film transistor array substrate and the color filter array substrate due to the liquid crystal's dielectric anisotropy. Light provided by a light source (not shown) is transmitted through the pixel electrode118, through the liquid crystal, and toward the upper substrate.

The first storage capacitor120includes a first lower storage electrode121extended from the second driving voltage supply line171, and a first upper storage electrode123overlapped with the first lower storage electrode121with the gate insulating film144between them. The first upper storage electrode123passes through the protective film150to connect, via a second contact hole115b, with the pixel electrode118.

The first storage capacitor120allows a pixel voltage charged in the pixel electrode118to be maintained until the next pixel voltage is charged.

The sensor TFT140includes a gate electrode108bextended from the second driving voltage supply line171, an active layer114boverlapped with the gate electrode108bwith having the gate insulating film144therebetween, a source electrode110belectrically connected to the active layer114band connected to the first driving voltage supply line152, and a drain electrode112bopposed to the source electrode110b. The drain electrode112bis formed in a “U” shape to create a wide channel area for receiving light.

Also, the sensor TFT140includes a third contact hole115cpassing through the protective film150and the gate insulating film144to partially expose the first driving voltage supply line152, and a fourth contact hole115dpassing through the protective film150to expose the source electrode110b. The sensor TFT140further includes a first transparent electrode pattern155contacted, via the third contact hole115c, with the source electrode110band contacted, via the third contact hole115d, with the first driving voltage supply line152. The first transparent electrode pattern155electrically connects the source electrode110bwith the first driving voltage supply line152. The active layer114bis formed in such a manner to partially overlap the source electrode110band the drain electrode112b. The sensor TFT140further includes a channel portion between the source electrode110band the drain electrode112b. An ohmic contact layer148bfor making ohmic contact with the source electrode110band the drain electrode112bis further formed on the active layer114b. Such a sensor TFT140plays a role in monitoring an external light incident into the panel. As used herein, to be “contacted with” and to be “connected to” both mean to be in direct contact and electrically connected.

A second storage capacitor180may include three or more sub-capacitors.FIG. 5Cillustrates a first sub-capacitor180aof second storage capacitor180. First sub-capacitor180ais formed of a second storage electrode182and the second driving voltage supply line171that overlap each other with the gate insulating film144between them. The second sub-capacitor180bis formed of the second storage electrode182and the first driving voltage supply line152that overlap each other with the gate insulating film144between them. The third sub-capacitor180cis formed of the second storage electrode182and the second transparent electrode pattern156that overlap each other with the protective film150between them. The second storage electrode182is connected to the source electrode110cof the second TFT170and the drain electrode112bof the sensor TFT140, respectively. The second transparent electrode pattern156is connected to the second driving voltage supply line171via a fifth contact hole115epassing through the gate insulating film144and the protective film150.

Second storage capacitor180serves to store a charge by a photo-induced current generated by the sensor TFT140.

Still referring toFIG. 5C, the second TFT170includes a gate electrode108c, which is a portion of the gate line102, a source electrode110cconnected to the second storage electrode182, a drain electrode112copposed to the source electrode110c, and an active layer114coverlapped with the gate electrode108c, which form a channel between the source electrode110cand the drain electrode112c. The gate electrode108cof the second TFT170is different from the gate electrode108aof the first TFT106. In other words, the gate electrode108aof the first TFT106has a shape that protrudes from the gate line102, but the gate electrode108cof the second TFT170substantially shows a portion of the gate line102. The active layer114cis formed in such a manner to partially overlap the source electrode110cand the drain electrode112cand further includes a channel portion between the source electrode110cand the drain electrode112c. An ohmic contact layer148cfor making ohmic contact with the source electrode110cand the drain electrode112cis further formed on the active layer114c.

Referring back toFIG. 3, the DC/DC converter174boosts or drops an input voltage from the power supply162to generate a voltage supplied to the liquid crystal display panel152. Such a DC/DC converter172may generate a gamma reference voltage, a gate high voltage VGH, a gate low voltage VGL and a common voltage Vcom.

The gamma voltage supplier168applies a plurality of gamma voltages to the data driver164.

The data driver164converts digital R, G, B, video data into analog gamma voltages (i.e., data signals) corresponding to gray level values in response to a control signal CS from the timing controller160. The data driver164applies the analog gamma voltages to the data lines D1to Dm.

The gate driver166sequentially applies a scanning pulse to the gate lines GL1to GLn in response to a control signal CS from the timing controller160to thereby select horizontal lines of the liquid crystal display panel152supplied with the data signals.

The readout integrated circuit portion202reads a sensing voltage sensed by sensor TFT140and supplied to the read-out line204. Thus, the read-out integrated circuit portion202enables a determination of an illumination distribution of the liquid crystal display panel, that is, the illumination areas on the liquid crystal display panel.

The ADC220converts an analog sensing voltage from the read-out integrated circuit portion202into a digital signal and supplies the converted digital signal to the timing controller160.

The timing controller160generates the control signals CS for controlling the gate driver166and the data driver164using vertical/horizontal synchronizing signals Vsync and Hsync and a clock signal DCLK input from the system170. The control signal CS for controlling the gate driver166may include a gate start pulse GSP, a gate shift clock GSC and a gate output enable signal GOE, etc. Further, the control signal CS for controlling the data driver64may include a source start pulse SSP, a source shift clock SSC, a source output enable signal SOE and a polarity signal POL, etc. The timing controller160realigns the R, G, B data from the system170to apply them to the data driver164.

Also, the timing controller160supplies a digital data supplied from the ADC220to the memory206and generates brightness control signals D1-DK at the backlight driver210using the illumination distribution data from the memory206.

The memory206stores data corresponding to the spatial distribution of external illumination of the liquid crystal display panel152. the spatial distribution of external illumination is measured by the plurality of sensor TFTs140. This data is written to the memory206by the timing controller160. The timing controller160retrieves this data (hereinafter the “illumination distribution data”) in a frame-like format, for controlling the backlight driver210.

The backlight driver210independently drives a plurality of light sources within the backlight212using a backlight driving voltage Vinv supplied from the power supply162under the control of the timing controller160.

Hereinafter, the backlight driver210and the backlight212will be described in detail with reference toFIG. 6.

The backlight212includes a plurality of light sources (l-k), which are arranged in a matrix at a rear side of the liquid crystal display panel152. Each of the k light sources is capable of being independently driven. Herein, the individual light sources210ato212kmay include LEDs, fluorescent lamps, etc.

The backlight driver210includes a first to a k(th) inverter circuit portions210ato212kcorresponding to each of the light sources212ato210k, and an inverter controller220for controlling the first to the k(th) inverter circuit portions210ato212k. The inverter controller220controls the first to the k(th) inverter circuit portions210ato210kusing the first to the K(th) brightness control signals D1to Dk from the timing controller160.

The backlight driver210independently drives the light sources depending upon a illumination distribution by the first to the K(th) brightness control signals D1to Dk from the timing controller160. In other words, the inverter controller220of the backlight driver210supplies more high-level voltage to light sources positioned at an area that is overlapped with the illumination area P1illuminated by external light to thereby supply more light to the illumination area of the liquid crystal display panel152. In doing so, it becomes possible to increase the contrast ratio.

In the liquid crystal display device having such a structure, since a photosensor is integrated within the liquid crystal display panel152, it is not necessary to add an external photosensor. Thus, cost is reduced.

Furthermore, the liquid crystal display device includes light sources212a-212kthat are independently capable of being driven and are arranged in a matrix formation at the rear side of the liquid crystal display panel152to thereby supply a light having a different brightness depending upon the illumination distribution of the liquid crystal display panel152. Accordingly, brightness of the light sources212a-212kcorresponding to the illumination area P1of the liquid crystal display panel152can be increased to thereby prevent a contrast ratio deterioration of the illumination area P1.

An exemplary process for driving the light sources212a-212k, based on a light sensing process according to the present invention will be described in detail as follows.

Referring toFIG. 7, if a first driving voltage Vdrv (for example, a voltage of approximately 10V) is applied to the source electrode110bof the sensor TFT140, a second driving voltage Vbias (for example, a voltage of approximately −5V) is applied to the gate electrode108bof the sensor TFT140and an external light is irradiated into a portion area of the liquid crystal display panel152shown inFIG. 2. Then the irradiated light impinging on the liquid crystal panel is sensed in the active layer114bof the sensor TFT140located at the illumination area P1. Accordingly, a photocurrent, which flows from the source electrode110bof the sensor TFT140to the drain electrode112bby way of a channel is provided. The photocurrent flows from the drain electrode112bof the sensor TFT140forward the second storage electrode182. Accordingly, a sensing voltage corresponding to the photocurrent is charged into the second storage capacitor180including the first sub-capacitor180a, which includes the second driving voltage supply line171and the second storage electrode182; the second sub-capacitor180b, which includes the second storage electrode182and the first driving voltage supply line152; and the third sub-capacitor,180c, which includes the second storage electrode182and the second transparent electrode pattern156. Thus, the sensing voltage charged into the second storage capacitor180is transmitted to the read-out integrated circuit portion202by way of the second TFT170and the read-out line204

Accordingly, an analog voltage sensed at the read-out integrated circuit portion202is converted, via the ADC220, into a digital signal, which is supplied to the timing controller160.

The timing controller160supplies the digital signal from the ADC220to the memory206, and the memory206stores an illumination distribution data. The illumination distribution data enables the distinguishing of the illumination area P1from the non-illumination area P2. The illumination area P1corresponds to the location of sensor TFTs140that sensed external light, and the non-illumination area P2corresponds to the locations of sensor TFTs140that did not sense external light.

For example, referring toFIG. 8, a illumination distribution data having an information on the non-illumination area P2and the illumination area P1may be stored in the form of a digital value of “0” and a digital value of “1” into the memory206, respectively.

The illumination distribution data in the memory206is supplied to the timing controller160and the timing controller160generates the brightness control signal D1to Dk using the illumination distribution data from the memory206, and supplies the brightness control signal D1to Dk to the backlight driver210. The backlight driver210independently controls the amount of light from each of the plurality of light sources of the backlight212using the brightness control signal D1to Dk.

A case where the liquid crystal display panel is divided into four unit areas, A, B, C and D, with one light source corresponding to each of these unit areas, as illustrated inFIG. 9, will be described as follows.

The inverter controller220of the backlight driver210is supplied with the first to fourth control signals D1to D4from the timing controller160to control a first to a fourth inverter circuit portion210ato210d. In other words, the inverter controller220supplies a pulse with modulated (PWM) or a pulse amplitude modulated (PAM) control signal to each respective inverter circuit210a-d. In doing so, the first brightness control signal D1is supplied to the first inverter circuit portion210a; the second brightness control signal D2is supplied to the second inverter circuit portion210b; the third brightness control signal D3is supplied to the third inverter circuit portion210c; and the fourth brightness control signal D1is supplied to the fourth inverter circuit portion210d. The first inverter circuit portion210adrives the first light source212acorresponding to the first area A of the liquid crystal display panel152; the second inverter circuit portion210bdrives the second light source212bcorresponding to the second area B of the liquid crystal display panel152, the third inverter circuit portion210cdrives the third light source212ccorresponding to the third area C of the liquid crystal display panel152; and the fourth inverter circuit portion210ddrives the fourth light source212dcorresponding to the fourth area D of the liquid crystal display panel152.

If the second area B is the illumination area P1, then the second inverter circuit portion210bsupplies a driving voltage (or a driving current) corresponding to the second brightness control signal D2from the timing controller160to the second light source212b, so that the second light source212bsupplies a light for compensating a deterioration of the contrast ratio reduced by the illumination of the second area B of the liquid crystal display panel152. As a result, a deterioration of the contrast ratio of the illumination area P1at the liquid crystal display panel152can be reduced.

Hereinafter, a method of fabricating a liquid crystal display panel containing a sensor TFT will be described in detail with reference toFIGS. 10A-14A,10B-14B, and10C-14C.

First, a gate metal layer is formed on a lower substrate142by a deposition technique such as a sputtering, etc. Next, the gate metal layer is patterned by a patterning technique such as a photolithography and etching process to provide gate patterns including the gate line102, the gate electrode108aof the first TFT106, the gate electrode108cof the second TFT170, the first driving voltage supply line152, the second driving voltage supply line171, the gate electrode108bof the sensor TFT140extended from the second driving voltage supply line171, and the first lower storage electrode121shown inFIG. 10A-C. The second driving voltage supply line171may be integral to the first lower storage electrode121of the first storage capacitor180and the gate electrode108bof the sensor TFT140.

Referring toFIG. 11A-C, a gate insulating film144is formed on the lower substrate142provided with the gate patterns by a deposition technique such as the PECVD, etc. An amorphous silicon layer and an amorphous silicon layer doped with an n+impurity are sequentially disposed on the substrate142provided with the gate insulating film144.

Next, the amorphous silicon layer and the amorphous silicon layer doped with an n+impurity are patterned by a photolithography process and an etching process using a mask to thereby provide the semiconductor patterns145a,145band145ccorresponding to the first and the second TFT106and170and the sensor TFT140, respectively illustrated inFIG. 10B. The semiconductor patterns145a,145band145cmay be formed in a double-layer of the active layers114a,114band114cand the ohmic contact layers148a,148band148c.

Referring toFIG. 12A-C, a source/drain metal layer is sequentially formed on the lower substrate142provided with the semiconductor patterns145a,145band145c. Next, source/drain patterns including the first upper storage electrode123overlapped with the first lower storage electrode121and the second storage electrode182connected to the drain electrode112bof the sensor TFT140is formed by using, for example, a photolithography process and etching process, using a mask with a pattern for the data line104, the source electrode10aand the drain electrode112aof the first TFT106, the source electrode110cand the drain electrode112cof the second TFT170, the source electrode10band the drain electrode112bof the sensor TFT140.

Referring toFIG. 13A-C, a protective film150may be entirely formed on the gate insulating film144provided with the source/drain patterns by a deposition technique such as the PECVD, etc. Then the protective film150is patterned by a photolithography and etching process to thereby provide a first contact hole115afor exposing the drain electrode112aof the first TFT106, a second contact hole115bfor exposing the first upper storage electrode123, a third contact hole115cfor exposing the first driving voltage supply line152, a fourth contact hole115dfor exposing the source electrode110bof the sensor TFT140, and a fifth contact hole115efor exposing the second driving voltage supply line171of the second storage capacitor180.

Referring toFIG. 14A-C, a transparent electrode material may be entirely disposed on the protective film150by a deposition technique such as the sputtering, etc. Then the transparent electrode material is patterned by a photolithography and etching process to thereby provide the pixel electrode118, the first transparent electrode pattern155, and the second transparent electrode pattern156.

The pixel electrode118is connected, via the first contact hole115a, to the drain electrode112aof the first TFT106and is connected, via the second contact hole1115b, to the first upper storage electrode123.

The first transparent electrode pattern155is connected, via the third contact hole115c, to the first driving voltage supply line152and is connected, via the fourth contact hole115d, to the source electrode10bof the sensor TFT140.

The second transparent electrode pattern156is partially overlapped with the second storage electrode182and is connected, via the fifth contact hole115e, to the first driving voltage supply line171. Accordingly, a thin film transistor array substrate having the sensor TFT is formed.

Next, in a separate process a black matrix is formed, which divides a color filter substrate into liquid crystal cell areas and prevents light leakage when the liquid crystal display device is driven. Further, the color filter array substrate containing a color filter, etc. is provided at the liquid crystal area defined by the black matrix. The color filter array substrate and the thin film transistor array substrate are then joined to each other to form the liquid crystal display panel containing the sensor TFT.

As described above, in the liquid crystal display device, the fabricating method and the driving method thereof, it is not necessary to add an external photo sensor because at least one photosensor is integrated within the liquid crystal display panel. Thus, cost is reduced.

Also, the liquid crystal display device includes light sources that arranged in a matrix formation at the rear side of the liquid crystal display panel152and are capable of being independently driven to thereby supply light having a light distribution corresponding to the illumination distribution to the liquid crystal display panel. Accordingly, brightness of the light sources corresponding to the illumination area P1of the liquid crystal display panel can be increased to thereby prevent contrast ratio deterioration at the illumination area.