KR20090095890A - Liquid crystal display device interated touch panel - Google Patents

Abstract

A liquid crystal display integrated touch panel preventing the malfunction of the liquid crystal display is provided to prevent noise generated to lead-out signal by individually locating the lead-out line and data line. A plurality of data lines crosses over RGB unit pixel to perpendicular direction. A photo TFT(Thin Film Transistor)(140) is formed in RGB unit pixel in order that the different unit pixel is administered so that a plurality of data lines be in a line. A read out line(119) is independently formed at the perpendicular direction the other side of the unit pixel in which the photo TFT is formed among the RGB unit pixel. The lead-out line is electrically connected to the second TFT(160). The lead-out line transmits the signal sensed from the photo TFT.

Description

Touch panel integrated liquid crystal display {LIQUID CRYSTAL DISPLAY DEVICE INTERATED TOUCH PANEL}

The present invention relates to a touch panel integrated liquid crystal display device, and more particularly, a data line for outputting red (R), green (G), and blue (B) data from the outside to a panel, and a specific position on the panel. The present invention relates to a touch panel integrated liquid crystal display configured to exclude signal interference due to parasitic capacitance occurring between read-out lines that recognize or read an image and transmit the signal to a controller.

In general, the liquid crystal display device displays an image by adjusting the light transmittance of the liquid crystal using an electric field. To this end, the liquid crystal display includes a liquid crystal display panel in which liquid crystal cells are arranged in a matrix, and a driving circuit for driving the liquid crystal display panel. The liquid crystal display panel includes a thin film transistor array substrate and a color filter substrate bonded to each other, a spacer positioned to maintain a constant cell gap between the two substrates, and a liquid crystal filled in the cell gap.

The thin film transistor array substrate includes a plurality of gate lines and data lines formed to cross each other, a thin film transistor which is a switch element formed at each intersection of the gate lines and data lines, and a liquid crystal cell unit connected to the thin film transistor. Pixel electrodes and the like, and an alignment film coated thereon. At this time, the gate line and the data lines are supplied with signals from the driving circuits through the respective pad units. The thin film transistor supplies a pixel voltage signal supplied to the data line to the pixel electrode in response to a scan signal supplied to the gate line.

The color filter substrate includes R, G, and B color filters formed in units of liquid crystal cells, a black matrix for distinguishing between the color filters and reflecting external light, a common electrode for supplying a reference voltage to the liquid crystal cells in common; It consists of an orientation film apply | coated on them.

The liquid crystal display panel is completed by separately manufacturing such a thin film transistor array substrate and a color filter substrate, bonding them, injecting liquid crystal, and then encapsulating the liquid crystal display panel.

In addition, in the related art, a liquid crystal display device having a function of sensing and displaying an external document or an external image as well as a simple display function has been introduced.

Hereinafter, a brief description will be made of a conventional image sensing device capable of sensing such an external image.

FIG. 1 is a plan view illustrating a pixel structure of a general liquid crystal display having an image sensing element, and FIG. 2 is along a first cutting line I-I 'and a second cutting line II-II' of FIG. 1. 3 is a circuit diagram illustrating an image sensing device formed in a unit pixel of FIG. 1.

As shown in FIGS. 1 to 3, the thin film transistor array substrate includes a photo TFT 40 for sensing an image, a storage capacitor 80 connected to the photo TFT 40, and a storage capacitor 80 therebetween. And a switching TFT 60 positioned opposite to or adjacent to the photo TFT 40.

At this time, the photo TFT 40 includes the gate electrode 11 formed on the substrate 10, the active layer 14 overlapping the gate electrode 11 with the gate insulating layer 13 therebetween, and the active layer 14. The driving source electrode 16 and the driving drain electrode 17 facing the driving source electrode 16 are electrically provided. The active layer 14 is formed to overlap the driving source electrode 16 and the driving drain electrode 17 and further includes a channel portion between the driving source electrode 16 and the driving drain electrode 17. An ohmic contact layer 15 for ohmic contact with the driving source electrode 16 and the driving drain electrode 17 is further formed on the active layer 14. Through such a configuration, the photo TFT 40 senses light incident by a predetermined image such as a document, a human fingerprint, or a touch pen.

The storage capacitor 80 is formed by overlapping a storage lower electrode formed by extending the gate electrode 11 of the photo TFT 40 and a storage upper electrode formed by extending the driving drain electrode 17 of the photo TFT 40. The storage capacitor 80 stores a charge due to the photocurrent generated in the photo TFT 40.

The switching TFT 60 includes a gate electrode 11 formed on the substrate 10, a source electrode 16 formed by partially overlapping the gate electrode 11, and a drain electrode 17 facing the source electrode 16. And an active layer 14 overlapping the gate electrode 11 and forming a channel between the source electrode 16 and the drain electrode 17. The active layer 14 is formed to overlap the source electrode 16 and the drain electrode 17, and further includes a channel portion between the source electrode 16 and the drain electrode 17. The ohmic contact layer 15 for ohmic contact with the source electrode 16 and the drain electrode 17 is further formed on the active layer 14.

Next, a method of driving an image sensing device, that is, a photo TFT, will be briefly described with reference to FIG. 3.

For example, a driving voltage of about 10V is applied to the driving source electrode 16 of the photo TFT 40, and a voltage of about -5V is applied to the gate electrode 11 to sense the light when the light is sensed on the active layer 14. According to the amount of light, a photo current path is generated which flows from the driving source electrode 16 to the driving drain electrode 17 via a channel. Since the photocurrent path flows to the storage upper electrode extending from the driving drain electrode 17 and the storage lower electrode is connected to the gate electrode 11 of the photo TFT 40, the storage capacitor 80 is charged with photocurrent. Is charged. As such, the charge charged in the storage capacitor 80 is transferred to the switching TFT 60 to read the image sensed by the photo TFT 40.

However, when the readout line 19 is formed adjacent to the data line 18 in a specific unit pixel of R, G, and B as in the related art, parasitic capacitance occurs between the data line 18 and the readout line 19. In this case, since the amount of current sensed by the photo TFT 40 and flowing through the readout line 19 or the signal is very small, a change in the data signal applied to the data line 18 is applied to the photo TFT 40. Coupling to the signal sensed by the (coupling) acts as a kind of noise (noise).

As a result, generation of noise through the lead-out line may cause malfunction of the liquid crystal display, such as to lower the reliability of the product of the liquid crystal display.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to arrange a lead out line of a photo TFT that senses an image at a specific unit pixel among R, G, and B unit pixels independently from a data line. A liquid crystal display device with integrated touch panel is provided.

According to an aspect of the present invention, there is provided a touch panel integrated liquid crystal display device comprising: a pixel area including pixels of R, G, and B units; A first TFT provided for each unit pixel of R, G, and B; A second TFT formed in one unit pixel of the R, G, and B pixel units; A photo TFT formed by being electrically connected to each other in a unit pixel in which the second TFT is located, and sensing light from the outside; A plurality of gates each partitioning the unit pixels of R, G, and B in a horizontal direction from a short side and driving the first TFT and the second TFT, wherein the second TFT is driven by a previous signal of the first TFT; Lines; The unit pixels of R, G, and B are divided in a direction perpendicular to the long side, and different unit pixels are formed on one side of the long side of the unit pixel in which the photo TFT is formed among the R, G, and B unit pixels. A plurality of data lines formed adjacent to each other so as to be managed; The R, G and B unit pixels are independently formed in a direction perpendicular to the other long side of the unit pixel on which the photo TFT is formed, and are electrically connected to the second TFT to transmit a signal sensed from the photo TFT. Lead-out line; And a first driving voltage line and a second driving voltage line which are formed in parallel with the gate line and connected to the gate electrode and the source electrode of the photo TFT, respectively.

In addition, another touch panel integrated liquid crystal display according to the present invention includes: a pixel region including pixels of R, G, and B units; A first TFT provided for each unit pixel of R, G, and B; A second TFT formed in one unit pixel of the R, G, and B pixel units; A sensing element formed by electrically connecting each unit pixel in which the second TFT is located; Each of the R, G, and B unit pixels is partitioned in a horizontal direction from a short side, and the first TFT and the second TFT are driven, but the second TFT is driven by the previous signal of the first TFT. A plurality of gate lines; The unit pixels of R, G, and B are divided in a direction perpendicular to the long side, and are different from one side of the long side of the unit pixel in which the photo TFT is formed among the R, G, and B unit pixels. A plurality of data lines formed adjacent to each other so as to manage the unit pixels; The R, G and B unit pixels are independently formed in a direction perpendicular to the other long side of the unit pixel on which the photo TFT is formed, and are electrically connected to the second TFT to transmit a signal sensed from the photo TFT. Read out lines; And a first driving voltage line and a second driving voltage line which are formed in parallel with the gate line and connected to the gate electrode and the source electrode of the photo TFT, respectively.

As a result of the above configuration, the liquid crystal display according to the present invention is designed so that the lead-out line for outputting a fine current signal from the unit pixel on which the photo TFT is formed and the data line to which the data signal is input from the outside are positioned independently of each other. The noise problem occurring in the out signal can be improved to prevent malfunction of the liquid crystal display.

Hereinafter, a touch panel integrated liquid crystal display according to the present invention will be described in more detail with reference to the accompanying drawings.

4 is a plan view illustrating a pixel structure of a touch panel integrated liquid crystal display according to an exemplary embodiment of the present invention, and FIG. 5 is along a third cutting line III-III 'and a fourth cutting line IV-IV' of FIG. 4. 6 is a circuit diagram illustrating an image sensing device formed in a unit pixel of FIG. 4.

As shown in FIG. 4, the touch panel integrated liquid crystal display according to the present invention includes a photo TFT 140 for sensing an image from the outside to one unit pixel among R, G, and B unit pixels constituting the pixel. In this case, the left and right long sides of the unit pixel including the photo TFT 140 are the same as the data lines 118a and 118b which are formed in parallel on each side and manage different unit pixels. A thin film transistor array substrate having a lead-out line 119 formed independently from the other side of the unit pixel to read a signal sensed from the photo TFT 140, and a color bonded to the thin film transistor array substrate by maintaining a cell gap And a filter substrate, a liquid crystal layer formed in the cell gap between the two substrates, and a backlight device provided on the rear surface of the two bonded substrates to provide light. .

As shown in the drawing, a plurality of gate lines 112, data lines 118, 118a, and 118b and lead-out lines 119 are formed on the thin film transistor array substrate to form unit pixels of R, G, and B. A region is defined (or partitioned), and is formed on one side of a pixel region having the unit pixel regions of R, G, and B as one pixel unit, and one unit pixel region among the unit pixel regions of the R, G, and B. And a photo TFT 140 for detecting light or an image from outside, a second storage capacitor 180 connected to the photo TFT 140, and a second storage capacitor 180 interposed therebetween. A second TFT 160 positioned in the opposite direction and connected to the lead out line 119 is included.

Here, the second TFT 160 is turned on to the scan signal (or gate voltage) of the previous step applied to the first TFT 150 and the second TFT 160 receives the signal detected from the photo TFT 140. Through the output to the lead out line 119.

In addition, the thin film transistor array substrate includes a first TFT 150 at an intersection where a plurality of gate lines 112 and data lines 118, 118a, and 118b cross and form each other. In this case, the first TFT 150 includes a first storage capacitor formed by overlapping the common voltage wiring 112a or the repair wiring and the pixel electrode 121 formed in the edge region of each of the R, G, and B pixel units. (170).

As shown in the drawing, a lead between the unit pixel region of B and the unit pixel region of R is read in the horizontal direction or the direction perpendicular to the gate line 112 between the unit pixel region of B and the R unit pixel region. The outline 119 is formed independently, while the data line 118a that manages the R unit pixels and the data line 118b that manages the G unit pixels are located between the R unit pixel region and the G unit pixel region. These are formed in parallel with each other at predetermined intervals.

As a result, the distance between the data line 118 that manages the unit pixel of B and the data line 118a that manages the unit pixel of R in the pixel region is the data line 118a that governs the unit pixel of R and the unit of G. The distances between the data lines 118b that govern the pixels are formed differently.

Of course, this may be understood in other ways. For example, when referring to the pixel area, the data line 118b that manages the unit pixel of G and the data line 118 that manages the unit pixel of B are parallel between the unit pixel area of G and the unit pixel area of B. While formed at predetermined intervals, the lead-out line 119 may be formed independently between the unit pixel regions of R and the unit pixel regions of G in a vertical direction.

Therefore, these examples may vary depending on how the unit pixels of R, G, and B constituting pixels are arranged, and thus are not particularly limited thereto. Above all, they are formed on specific unit pixels constituting the pixel to sense and output an image. The lead-out line 119 connected to the photo TFT 140 is required to be formed independently from the data lines 118, 118a, and 118b.

Through this, the minute signal sensed from the photo TFT 140 and output to the readout line 119 is freed from the data signal inputted from the outside through the data lines 118, 118a, and 118b, thereby causing signal distortion such as noise. Can be prevented in advance.

In addition, R formed at the previous stage (or the previous horizontal line) at one side of the short side of the unit pixel region in which the photo TFT 140 and the second TFT 160 are positioned in the unit pixel regions of R, G, and B, A first driving voltage line 112b and a second driving voltage line 112c, which are horizontally disposed on the gate line 112 that respectively manages the unit pixels of G and B, and drive the photo TFT 140, are formed. In this case, the first driving voltage line 112b is a driving voltage line for turning on / off the photo TFT 140, and the second driving voltage line 112c is a driving voltage line applied to the source electrode of the photo TFT 140. .

The first TFT 150 includes a gate electrode connected to the gate line 112, a source electrode connected to the data lines 118, 118a, and 118b, a drain electrode connected to the pixel electrode 121, and a gate electrode. An active layer, that is, an amorphous silicon layer, which overlaps and forms a channel between the source electrode and the drain electrode, is provided. In this case, the active layer is partially overlapped with the source electrode and the drain electrode, and further includes a channel portion between the source electrode and the drain electrode. An ohmic contact layer, that is, an n + amorphous silicon layer, for the ohmic contact with the source electrode and the drain electrode is further formed on the active layer. Here, the active layer and the ohmic contact layer may be referred to collectively as a semiconductor pattern. The first TFT 150 as described above allows the pixel voltage signal supplied to the data lines 118, 118a, and 118b to be charged and held in the pixel electrode 121 in response to the gate signal supplied to the gate line 112.

The pixel electrode 121 is connected to the drain electrode of the first TFT 150 through the first contact hole formed in the passivation layer. The pixel electrode 121 generates a potential difference with the common electrode formed on the color filter substrate by the charged pixel voltage. Due to this potential difference, the liquid crystal positioned between the thin film transistor array substrate and the color filter substrate is rotated by the dielectric anisotropy, and light incident through the pixel electrode 121 from the backlight is transmitted through the substrate.

As described above, the first storage capacitor 170 is formed by overlapping pixel electrodes with the common voltage wiring 112a interposed between the gate insulating layer and the passivation layer. The first storage capacitor 170 is the pixel electrode 121. ) Is maintained until the next pixel voltage is charged.

The photo TFT 140 is electrically connected to the active layer and the active layer formed by overlapping the gate electrode with the gate electrode and the gate insulating film extending from the first driving voltage line 112b interposed therebetween, and the second driving voltage line 112c. And a drain electrode facing the source electrode. The drain electrode of the photo TFT 140 is, for example, formed in a “U” shape, so that a channel region for receiving light can be formed wide.

In addition, the photo TFT 140 may include a second contact hole through which the second driving voltage line 112c is partially exposed through the gate insulating film and the passivation layer, and is connected to the source electrode through the second contact hole, and the second contact hole is formed. A transparent electrode pattern (not shown) connected to the second driving voltage line 112c through the hole may be provided. The transparent electrode pattern serves to electrically connect the source electrode of the photo TFT 140 and the second driving voltage line 112c. The active layer is partially overlapped with the source electrode and the drain electrode, and further includes a channel portion between the source electrode and the drain electrode. An ohmic contact layer for ohmic contact with the source electrode and the drain electrode is further formed on the active layer. The photo TFT 140 serves to sense incident light by a predetermined image such as a document or a fingerprint of a person.

The second storage capacitor 180 is connected to the drain electrode of the second TFT 160 and the gate electrode of the photo TFT 140, respectively, and has a gate electrode and a photo TFT 140 extending from the first driving voltage line 112b. Is formed by overlapping the drain electrodes. The second storage capacitor 180 stores the charge due to the photo current generated in the photo TFT 140.

The second TFT 160 includes a gate electrode which is a part of the front gate line 112, a source electrode formed by overlapping a part of the gate electrode, a drain electrode facing the source electrode, and overlapping the gate electrode with the source electrode and the drain. The active layer which forms a channel between electrodes is provided. The active layer is formed to partially overlap the source electrode and the drain electrode and further includes a channel portion between the source electrode and the drain electrode. An ohmic contact layer for ohmic contact with the source electrode and the drain electrode is further formed on the active layer.

Now, a brief description will be made of a method of manufacturing a thin film transistor array substrate with reference to FIG. 5.

First, a metal film is deposited on the lower substrate 100 through a deposition method such as sputtering, and then a gate line 112, a common voltage line 112a or a repair line, and a first TFT through a photolithography process. A gate electrode of 150, a gate electrode 111 of second TFT 160, a first driving voltage line 112b, a second driving voltage line 112c, and a first driving voltage line 112b. Gate patterns including the gate electrode 111 of the photo TFT 140 are simultaneously formed. At this time, the first driving voltage line 112b and the gate electrode 111 of the photo TFT 140 are integrally formed with each other.

Subsequently, the gate insulating layer 113 is formed on the lower substrate 100 on which the gate patterns are formed through a chemical vapor deposition method such as PECVD. In this case, an active layer 114, that is, an amorphous silicon layer and an ohmic contact layer 115, that is, an n + amorphous silicon layer is sequentially formed on the lower substrate 100 on which the gate insulating layer 113 is formed.

Thereafter, the active layer 114, the ohmic contact layer 115 are patterned through a photolithography process using a photo mask to correspond to the first TFT 150, the second TFT 160, and the photo TFT 140, respectively. To form semiconductor patterns. Here, the semiconductor pattern represents the active layer 114 and the ohmic contact layer 115 as mentioned above.

As such, after depositing a metal layer for forming a source / drain electrode on the lower substrate 100 on which the semiconductor pattern and the contact hole are formed, the data lines 118, 118a, and 118b and the first TFT are formed through a photolithography process. Source electrode and drain electrode of 150, source electrode 116 and drain electrode 117 of second TFT 160, source electrode 116 and drain electrode 117 of photo TFT 140, and first Source / drain patterns including the drain electrode 117 of the photo TFT 140 overlapping the gate electrode extended to the supply voltage line 112b are formed.

Subsequently, after the passivation layer 120 is formed on the entire surface of the lower substrate 100 using a deposition method such as PECVD on the gate insulating layer 113 on which the source / drain patterns are formed, the first TFT 150 is formed through a photolithography process. The first contact hole for exposing the drain electrode of the ()) to the outside, and at the same time to electrically connect the second supply voltage line 112c and the source electrode of the photo TFT 140, the protective film 120 and the gate insulating film 113 ) To form a second contact hole.

The pixel electrode 121 is formed by depositing a transparent electrode material on the entire surface of the lower substrate 100 by sputtering or the like on the protective layer 120 and then patterning the transparent electrode through a photolithography process. In this case, the pixel electrode 121 contacts the drain electrode of the first TFT 150 through the first contact hole. In addition, the transparent electrode pattern contacts the second driving voltage line 112c through the second contact hole and at the same time contacts the source electrode 116 of the photo TFT 140.

Referring to FIG. 6 together, the driving method of the image sensing device having the above structure, that is, the photo TFT will be briefly described.

First, the second driving voltage Vdrv is applied to the source electrode of the photo TFT 140, and at the same time, the first driving voltage Vbias is applied to the gate electrode of the photo TFT 140, and a predetermined voltage is applied to the active layer of the photo TFT 140. When light is sensed, light current flowing from the source electrode of the photo TFT 140 to the drain electrode via the channel is generated according to the sensed amount of light.

This photocurrent flows from the drain electrode of the photo TFT 140 to the storage electrode of the second storage capacitor 180, thereby charging the second storage capacitor 180 with the charge due to the photocurrent.

Thereafter, the charge charged in the second storage capacitor 180 is read by the read out IC through the second TFT 160 and the read out line 119. That is, the signal detected by the readout integrated circuit varies according to the amount of light sensed by the photo TFT 140, so that an image such as a document, an image scan, a touch input, or the like can be sensed. The sensed image may be transmitted to a controller or implemented on a screen of the liquid crystal display according to a user's adjustment.

Meanwhile, the present invention is not limited to the photo TFT 140 which detects a signal according to the amount of light sensed as a sensing element for detecting position coordinates, and after reading a voltage value changed by a resistance value at a specific position, It can also be applied to a resistive film method that can detect the position coordinates according to the change of the potential difference in the apparatus. In this case, a resistive sensor is typically arranged to be isolated by a spacer and to be in contact with each other by pressing.

 Furthermore, the sensing element of the present invention can be applied to a capacitive method capable of detecting a position coordinate according to a change in potential difference in a control device after reading a voltage value changed by a capacitance value at a specific position, wherein The capacitive sensor may be configured in such a manner as to use capacitance coupling in the state of applying an AC voltage or the like.

Therefore, in the present invention, even when the resistance element or the capacitance sensor is included in the touch panel integrated liquid crystal display as a sensing element, the lead-out line for detecting the sensing signal is a signal generated by parasitic capacitance with the data line. In order to prevent distortion, it is preferable to form them independently from each other.

1 is a plan view illustrating a pixel structure of a general liquid crystal display device having an image sensing element.

FIG. 2 is a cross-sectional view taken along the first cutting line I-I 'and the second cutting line II-II' of FIG.

3 is a circuit diagram illustrating an image sensing device formed in a unit pixel of FIG. 1.

4 is a plan view illustrating a pixel structure of a touch panel integrated liquid crystal display according to an exemplary embodiment of the present invention.

5 is a cross-sectional view taken along the third cut line III-III 'and the fourth cut line IV-IV' of FIG. 4.

6 is a circuit diagram illustrating an image sensing device formed in a unit pixel of FIG. 4.

Claims (7)

A pixel region constituting a pixel including unit pixel regions of red (R), green (G), and blue (B); A first TFT (Thin Film Transistor) provided for each unit pixel of R, G, and B; A second TFT formed in one unit pixel of the R, G, and B pixel units; A photo TFT formed by being electrically connected to each other in the unit pixel in which the second TFT is located, and sensing light from the outside; Each of the R, G, and B unit pixels is partitioned in a horizontal direction from a short side, and the first TFT and the second TFT are driven, but the second TFT is driven by the previous signal of the first TFT. A plurality of gate lines; The unit pixels of R, G, and B are divided in a direction perpendicular to the long side, and are different from one side of the long side of the unit pixel in which the photo TFT is formed among the R, G, and B unit pixels. A plurality of data lines formed adjacent to each other so as to manage unit pixels; The R, G and B unit pixels are independently formed in a direction perpendicular to the other long side of the unit pixel on which the photo TFT is formed, and are electrically connected to the second TFT to transmit a signal sensed from the photo TFT. Read out line; And a first driving voltage line and a second driving voltage line which are formed to be parallel to the gate line and connected to the gate electrode and the source electrode of the photo TFT, respectively. The liquid crystal display device according to claim 1, wherein the source electrode of the second TFT is connected to the drain electrode of the photo TFT. The liquid crystal display of claim 2, wherein the source electrode of the second TFT and the drain electrode of the photo TFT further include a second storage capacitor formed to overlap the first driving voltage line. The liquid crystal display device according to claim 1, wherein the drain electrode of the second TFT is connected to the lead out line. The liquid crystal display of claim 1, wherein the source electrode of the photo TFT is connected to a second driving voltage line. A pixel region constituting a pixel including unit pixel regions of red (R), green (G), and blue (B); A first TFT (Thin Film Transistor) provided for each unit pixel of R, G, and B; A second TFT formed in one unit pixel of the R, G, and B pixel units; A sensing device formed by electrically connecting each unit pixel in which the second TFT is located; Each of the R, G, and B unit pixels is partitioned in a horizontal direction from a short side, and the first TFT and the second TFT are driven, but the second TFT is driven by the previous signal of the first TFT. A plurality of gate lines; The unit pixels of R, G, and B are divided in a direction perpendicular to the long side, and are different from one side of the long side of the unit pixel in which the photo TFT is formed among the R, G, and B unit pixels. A plurality of data lines formed adjacent to each other so as to manage unit pixels; The R, G and B unit pixels are independently formed in a direction perpendicular to the other long side of the unit pixel on which the photo TFT is formed, and are electrically connected to the second TFT to transmit a signal sensed from the photo TFT. Read out line; And a first driving voltage line and a second driving voltage line which are formed to be parallel to the gate line and connected to the gate electrode and the source electrode of the photo TFT, respectively. The liquid crystal display of claim 6, wherein the sensing element comprises one of a photo TFT, a resistive sensor, and a capacitive sensor.

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