KR101481666B1 - Liquid Crystal Display Device and Method for Driving the Same - Google Patents

Abstract

The present invention relates to a liquid crystal display device and a method of driving the same that minimize the deterioration of a touch sensing element by adjusting application of a driving voltage when a touch sensor is provided in a liquid crystal panel. A liquid crystal panel having a plurality of gate lines and a data line defining a pixel region, a pixel transistor in the pixel regions, a touch sensor portion, and a lead-out line connected to an output terminal of the touch sensor portion; A timing controller for controlling a driving timing of the driving circuit; a backlight unit for applying light to a back surface of the liquid crystal panel; Out integrated circuit connected in common to the lead-out integrated circuit; A touch sensing control unit for generating a touch enable signal for switching to a touch sensing state in accordance with the touch enable signal, And a driving voltage supply circuit for supplying the driving voltage differently.

Device Degradation, Touch Sensing, Photo Sensor, Counter

Description

[0001] The present invention relates to a liquid crystal display device and a method of driving the same,

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device in which deterioration of a touch sensing element is minimized by controlling application of a driving voltage when a touch sensor is provided in a liquid crystal panel, and a driving method thereof.

In recent years, as the information age has come to a full-fledged information age, a display field for visually expressing electrical information signals has been rapidly developed. In response to this, various flat panel display devices having excellent performance of thinning, light weight, Flat Display Device) has been developed to replace CRT (Cathode Ray Tube).

Specific examples of such flat panel display devices include a liquid crystal display device (LCD), a plasma display panel (PDP), a field emission display (FED) (Electro Luminescence Display Device: ELD). In general, a flat panel display panel that realizes an image is an essential component. The flat panel display panel has a pair of light emitting or polarizing material layers interposed therebetween And a transparent insulating substrate facing each other.

In a liquid crystal display device, an image is displayed by adjusting the light transmittance of a liquid crystal using an electric field. To this end, the image display apparatus includes a display panel having a liquid crystal cell, a backlight unit for irradiating the display panel with light, and a drive circuit for driving the liquid crystal cell.

The display panel is formed such that a plurality of gate lines and a plurality of data lines intersect to define a plurality of unit pixel regions. At this time, each pixel region includes a thin film transistor array substrate and a color filter array substrate facing 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 gate lines and data lines, a thin film transistor formed as a switching element for each intersection of the gate lines and the data lines, a pixel electrode formed in a unit of a liquid crystal cell and connected to the thin film transistor, And an applied alignment film. The gate lines and the data lines are supplied with signals from the driving circuits through respective pad portions.

Here, the thin film transistor supplies a pixel voltage signal to the pixel electrode in response to a scan signal supplied to the gate line, the pixel voltage signal being supplied to the data line.

The color filter array substrate includes color filters formed in units of liquid crystal cells, a black matrix for separating color filters and reflecting external light, a common electrode for supplying a reference voltage commonly to the liquid crystal cells, and the like, .

The thin film transistor substrate thus manufactured and the color filter array substrate are aligned by aligning each other, then the liquid crystal is injected and sealed.

In the liquid crystal display device thus formed, a light sensor is formed inside a display panel to control the backlight unit according to the brightness of external light, and the touch panel, which has been increased in volume by being attached to the outside of the display panel, There is an increasing effort to do this.

Hereinafter, a conventional liquid crystal display device will be described with reference to the accompanying drawings.

1 is a circuit diagram showing an equivalent circuit diagram of an active matrix type liquid crystal display device.

A thin film transistor (hereinafter referred to as "TFT") is mainly used as a switching element used in an active matrix type liquid crystal display device as shown in Fig.

1, an active matrix type liquid crystal display device converts digital video data into an analog data voltage on the basis of a gamma reference voltage and supplies the analog data voltage to a data line DL, and simultaneously supplies a scan pulse to a gate line GL And charges the liquid crystal cell Clc with the data voltage. To this end, the gate electrode of the TFT is connected to the gate line GL, the source electrode thereof is connected to the data line DL, and the drain electrode of the TFT is connected to the pixel electrode of the liquid crystal cell Clc and the storage capacitor Cst1 And is connected to one electrode. A common voltage Vcom is supplied to the common electrode of the liquid crystal cell Clc. The storage capacitor Cst1 functions to charge the data voltage applied from the data line DL when the TFT is turned on to maintain the voltage of the liquid crystal cell Clc constant. When a scan pulse is applied to the gate line GL, the TFT is turned on to form a channel between the source electrode and the drain electrode to apply a voltage on the data line DL to the pixel electrode of the liquid crystal cell Clc Supply. At this time, the liquid crystal molecules of the liquid crystal cell Clc are changed in arrangement by the electric field between the pixel electrode and the common electrode to modulate the incident light.

On the other hand, a liquid crystal display device is a passive light emitting device that adjusts brightness of a screen by using a backlight generated from a backlight unit disposed on the back surface of a liquid crystal panel.

Recently, a technique of attaching a touch screen panel on such a liquid crystal display device has been proposed. A touch screen panel generally refers to a user interface that is attached to a display device and detects the touch point at a touch point that is in contact with an opaque object such as a finger or a pen. When a user's finger, touch pen, or the like touches the screen, the liquid crystal display with the touch screen panel detects the contact position information and can implement various applications based on the detected information have.

However, such a liquid crystal display device causes various problems such as a rise in cost due to the touch screen panel, a decrease in yield due to the step of bonding the touch screen panel onto the liquid crystal panel, a decrease in luminance of the liquid crystal panel, and an increase in thickness.

2 is a diagram for explaining an operation of a general touch sensor unit.

In order to solve the above-described problems of the above-described attachment type touch panel, in recent years, a touch sensor unit including a sensing transistor is formed in a liquid crystal cell Clc of a liquid crystal display device A touch panel in-cell method has been proposed. The touch sensor unit includes a sensing transistor that generates a photocurrent i differently according to a change in the amount of light incident from the outside, a sensing capacitor Cst2 that stores charges by the photocurrent i, and an output of charges stored in the sensing capacitor Cst2. And a switching transistor for switching. A bias voltage Vbias set at a voltage equal to or lower than the threshold voltage of the sensing transistor is supplied to the gate electrode of the sensing transistor. The touch sensor unit is configured such that the photocurrent of the sensing transistor corresponding to the touched portion is larger than the photocurrent of the sensing transistor corresponding to the non-touched portion in a dark illumination environment (indoor environment) than the backlight, The photocurrent of the sensing transistor corresponding to the touched portion is different from the photocurrent of the sensing transistor corresponding to the non-touched portion, thereby generating the photodetection signals in the touched or untouched portions differently from each other. The liquid crystal display device can detect the contact position information of the user's finger or the like based on the light sensing signal of the touch sensor unit.

However, the conventional touch panel in-cell liquid crystal display device has the following problems.

First, in order to perform light sensing operation, a sensing transistor built in a cell type liquid crystal display device, which is a conventional touch panel, must continuously receive a DC driving voltage Vdrv of high potential through its drain electrode, There is a problem of deterioration. Such deterioration of the sensing transistor lowers the output characteristics of the touch sensor unit and causes an error in the light sensing signal to be outputted, which is a factor that lowers the reliability of the touch sensor unit.

Secondly, when the sensing transistor is deteriorated, the touch sensor unit may output a non-touch sensing signal even if the user's finger touches the liquid crystal cell formed on the touch sensor unit. On the other hand, There is a possibility of outputting a touch sensed signal even if it is not touched. The cell type liquid crystal display device which is a touch panel panel senses a touch point only by a relative photocurrent difference flowing through the sensing transistors. Thus, if deterioration of the sensing transistor occurs, it is impossible to accurately detect whether or not the touch transistor is actually touched. For example, in a strong illuminance environment such as the outside, even when a finger or the like is not touched to the liquid crystal panel and a shadow due to external light is generated, there is a problem that the touch is mistaken as a touch as in the case of being actually touched.

The present invention provides a liquid crystal display device and a method of driving the same that minimize deterioration of a touch sensing element by controlling application of a driving voltage when a touch sensor is provided in a liquid crystal panel, Well, that is the purpose.

According to an aspect of the present invention, there is provided a liquid crystal display device including a plurality of gate lines and data lines crossing each other to define a pixel region, a pixel transistor in the pixel regions, a touch sensor portion, A driving circuit for supplying a driving signal to each of the gate line and the data lines; a timing controller for controlling a driving timing of the driving circuit; A lead-out integrated circuit to which a lead-out line of the touch sensor unit is commonly connected, and a touch-sensitive circuit which switches to a touch sensing state according to a user's instruction and an output of the lead- A touch sensing control unit for generating an enable signal and an enable signal, The high-potential voltage required for the touch sensor of the drive in the reverse and, to a low potential voltage, as made by a drive voltage supply circuit for supplying to a different level of the voltage has its features.

The user's instruction may be made by an external button formed outside the liquid crystal panel.

The switching from the high potential voltage to the low potential voltage of the driving voltage supply circuit can be made when the output value from the lead-out integrated circuit does not change for a predetermined time.

The driving voltage supply circuit may further include a counter for counting a time duration of the low potential voltage.

In some cases, a transparent conductive film may be formed on the entire surface of the liquid crystal panel corresponding to the contact surface of the liquid crystal panel.

According to another aspect of the present invention, there is provided a method of driving a liquid crystal display device including a plurality of pixel regions, each pixel region including a pixel transistor, The touch sensor includes a liquid crystal panel, a driving voltage supply circuit for generating a driving voltage signal to control whether the touch sensor is driven, a lead-out integrated circuit connected to the touch sensor for outputting, The method comprising the steps of: switching a low-level to high-level enable signal to the drive voltage supply circuit in response to a user's judgment; Applying a high driving voltage to the touch sensor unit in the driving voltage supply circuit in synchronism with the driving voltage supplied to the touch sensor unit, The method of claim 1, further comprising the steps of: determining whether an output from the lead-out integrated circuit has not changed for a first time or longer; switching the touch enable signal to a low level when an output from the lead- Applying a driving voltage having a low potential to the touch sensor unit in a driving voltage supply circuit; And supplying the touch enable signal to the high level after a lapse of a second time and counting a second time after the low level switching and applying a high potential driving voltage to the touch sensor unit in the driving voltage supply circuit And the like.

According to another aspect of the present invention, there is provided a method of driving a liquid crystal display device including a plurality of pixel regions, each pixel region including a pixel transistor, The touch sensor includes a liquid crystal panel, a driving voltage supply circuit for generating a driving voltage signal to control whether the touch sensor is driven, a lead-out integrated circuit connected to the touch sensor for outputting, ; A method of driving a liquid crystal display including touch sensing means, the method comprising: supplying a touch-sensitive enable signal to the driving voltage supply circuit from a low level to a high level according to a user's judgment; The method comprising the steps of: applying a high-potential driving voltage to the touch sensor unit in the driving voltage supply circuit in synchronization with a signal; determining whether the output from the lead-out integrated circuit does not change for a first time or longer; Switching the touch enable signal to a low level when an output from the circuit does not pass a first time and applying a driving voltage of a low potential to the touch sensor unit in the driving voltage supply circuit; Means for switching the touch enable signal to a high level after sensing the touch, And applying a high potential driving voltage to the touch sensor unit. The driving voltage supply circuit may further include a counter for counting a second time. The contact sensing means may be formed of a transparent conductive film attached to the contact surface side of the liquid crystal panel.

In the above-described method, the judgment of the user is made by pressing an external button on the liquid crystal panel.

When the output from the lead-out integrated circuit is within the first time, the step of determining whether the output from the lead-out integrated circuit is not the first time or longer includes: maintaining the touch enable signal at a high level; And a high-potential driving voltage is applied from the voltage supply circuit to the touch sensor unit.

The liquid crystal display of the present invention and its driving method as described above have the following effects.

First, the liquid crystal display device and the driving method thereof according to the present invention are provided with an external button to perform a touch only when a user instructs the liquid crystal display device. When the liquid crystal display device is used as a small application such as a mobile phone, It is possible to prevent a malfunction from occurring in the battery.

Second, a voltage can be selectively applied according to a user's instruction, and when there is no instruction from the user, a high voltage is not applied to the touch sensor part, particularly the sensing transistor side, Can be minimized. Particularly, in the case of the photodetector transistor, the amorphous silicon included in the transistor can be prevented from deteriorating due to the temperature rise when the high voltage is continuously applied.

Third, when there is no output value calculated according to the output value from the lead-out integrated circuit at the time of driving, the low potential is applied to the driving voltage supply circuit side to prevent the high potential driving of the meter, .

Fourth, after a low potential of the meter is applied, a touch is sensed through a separate touch sensing means, and a driving voltage is switched over to a high potential or a counter is provided so that a specific time elapses , The touch detection can be performed without malfunction.

Fifthly, a touch sensor unit, which is ultimately built in the liquid crystal panel together with the thin film transistor array, may be provided and may include an in-cell type touch panel. The touch panel may include an external button suitable for preventing deterioration, So that the deterioration of the touch sensor unit is minimized and the reliability of the liquid crystal panel having a touch sensing function can be improved even for a long time driving.

Hereinafter, a liquid crystal display device and a driving method thereof according to the present invention will be described in detail with reference to the accompanying drawings.

Fig. 3 is a block diagram showing the liquid crystal display device of the present invention. Fig. 4 is a circuit diagram specifically showing each pixel in Fig. 3, and Fig. 5 is a circuit diagram showing a driving voltage signal Fig.

3, the liquid crystal display of the present invention includes a plurality of gate lines G0, G1, ..., Gn-1, Gn and a plurality of data lines D1, D2, ..., Dm 1, Dm) and a plurality of driving voltage supply lines (VL1, VL2, ..., Vn-1, VLn) are crossed and a pixel transistor A data driving circuit 20 for supplying a data voltage to the data lines D1, D2, ..., Dm-1, Dm; A gate drive circuit 30 for supplying scan pulses to the scan lines G0, G1, ..., Gn-1, Gn and a timing for controlling the drive timings of the data drive circuit 20 and the gate drive circuit 30 A touch sensing controller 50 for generating a touch enable signal TS for switching to a touch sensing state according to a user's instruction; Driving of sensor part A drive voltage supply circuit 60 for supplying the voltage to the drive voltage supply lines VL1, VL2, ..., VLn-1, VLn with a different voltage level by a touch-driving voltage and a touch- A backlight unit 70 for irradiating light to the back surface of the liquid crystal panel 10 and read-out lines ROL1, ROL2, ..., ROLm of the liquid crystal panel 10 are common And a lead-out integrated circuit 80 connected thereto.

Here, the liquid crystal panel 10 includes an upper substrate including a color filter, a lower substrate on which pixel regions P including a pixel transistor, a pixel circuit including a liquid crystal capacitor, a storage capacitor, and a touch sensor are formed, And a liquid crystal layer interposed between the lower substrate and the lower substrate.

As shown in the figure, the touch sensor unit may be formed for each pixel region, or may be formed for every n (n is a natural number) pixel regions. It is preferable that one finger is formed on an area corresponding to one contact area in consideration of the area where the finger touches the surface of the liquid crystal panel 10. [

A plurality of data lines D1, D2, ..., Dm and a plurality of gate lines G0, G1, G2, ..., Gn are orthogonal to each other on the lower substrate of the liquid crystal panel 10, A plurality of driving voltage supply lines VL1, VL2, ..., VLn parallel to the gate lines G0, G1, G2, ..., Gn, gate lines G0, G1, G2, A plurality of lead-out lines ROL1, RO2, ..., and ROLm that are orthogonal to the drive voltage supply lines VL1, VL2, ..., and VLn are formed. Here, the plurality of driving voltage supply lines and the lead-out lines may be formed of numbers corresponding to the number of gate lines and the number of data lines, respectively, when the touch sensor unit is formed for each pixel region, the driving voltage supply line and the lead-out lines may be selectively formed corresponding to the position of the touch sensor unit.

As shown in FIG. 4, at intersections of the data lines D1, D2, ..., Dm and the gate lines G1, G2, ..., Gn, And a touch sensor part P2 is formed at the intersection of the drive voltage supply lines VL1, VL2, ..., VLn and the lead-out lines ROL1, ROL2, ..., ROLm do.

The data driving circuit 20 outputs the digital video data R, G and B in response to a data control signal DDC from the timing controller 40 to the gamma reference voltages (GMA), and supplies the analog gamma compensation voltage to the data lines D1 to Dm of the liquid crystal panel 10 as a data voltage.

The gate driving circuit 30 generates a scan pulse in response to a gate control signal GDC from the timing controller 40 and sequentially supplies the scan pulse to the gate lines G1 to Gn, The horizontal line of the liquid crystal panel 10 is selected.

The timing controller 40 rearranges the digital video data (R, G, B) from the system (not shown) in accordance with the liquid crystal panel 10 and supplies them to the data driving circuit 20. The timing controller 40 includes a data control signal DDC for controlling the data driving circuit 20 using the timing control signals Vsync, Hsync, DCLK and DE from the system, Out control signal RDC for controlling the read-out integrated circuit 80. The read-out control signal RDC for controlling the read-

The touch sensing controller 50 operates by inputting an external button or receiving a touch control signal TC from the lead-out integrated circuit 80 to generate a touch enable signal TS).

Here, the touch enable signal TS is generated according to the application of an external button or the output value of the lead-out integrated circuit, and the touch enable signal TS is a TTL (Transistor Transistor Logic level signal.

The driving voltage supply circuit 60 includes a level shifter therein. Using this level shifter, the driving voltage supply circuit 60 shifts the level of the touch enable signal TS to match the driving of the touch sensor section P2 in the pixel region P, As a result, the driving voltage Vdrv swings between the high potential VH and the low potential Vl to generate a first supply voltage VL1, ..., VLn of the driving voltage supply lines VL1, ..., VLn, To the lines VL1a, VL2a, ..., VLna. Here, during a period in which the driving voltage Vdrv is generated at the high potential VH corresponding to the touch-on signal, the touch sensor unit P2 performs an optical sensing operation and performs a touch- The touch sensor unit P2 stops the optical sensing operation during a period in which the driving voltage Vdrv is generated at the low potential VL corresponding to the signal. Further, although not shown, the drive voltage supply circuit 60 generates a bias voltage and supplies it to the second supply lines VL1b to VLnb of the drive voltage supply lines VL1 to VLn.

Meanwhile, the backlight unit 70 includes a plurality of lamps installed on the back surface of the liquid crystal panel 10 so as to overlap with the liquid crystal panel 116. The lamp used in the backlight unit 70 can be any one of cold cathode fluorescent lamp (CCFL), external electrode fluorescent lamp (EEFL), and heat cathode fluorescent lamp (HCFL) have. The lamps irradiate light to the back surface of the liquid crystal panel 10 by driving an inverter (not shown). Meanwhile, the backlight unit 70 may have a plurality of light emitting diodes instead of or in combination with the lamps.

The lead-out integrated circuit 80 includes a plurality of circuits respectively connected to the lead-out lines ROL1, ROL2, ..., RLOm of the liquid crystal panel 10, and the lead-out lines ROL1, ROL2, ..., RLOm. .., RLOm) into a digital signal and supplies the digital signal to a system (not shown). The system performs processing of the touch recognition and coordinate calculation through the touch algorithm, and reflects the result of the operation to the liquid crystal panel 10 again.

On the upper substrate of the liquid crystal panel 10, a black matrix for covering the boundary between the pixels P is formed. A common electrode to which a common voltage is supplied in opposition to the pixel electrode with the liquid crystal layer interposed therebetween is formed on the upper substrate in a vertical electric field mode such as TN (Twisted Nematc) mode and VA (Vertical Alignment) Mode and a FFS (Fringe Field Switching) mode.

Hereinafter, a touch sensor unit having a touch sensing function provided in a pixel will be described in detail.

4, a pixel P includes a pixel circuit P1 formed at an intersection of a j-th gate line Gj and a j-th data line Dj, a j-th first supply line VLja, and j And a touch sensor unit P2 formed at an intersection of the second supply line VLjb and the j-th lead-out line ROLj. Here, the first supply line VLja corresponds to a storage voltage supply line, and the second supply line VLjb corresponds to a supply line for touch sensing.

The pixel circuit P1 includes a liquid crystal cell Clc and a pixel transistor TFT1 for driving the liquid crystal cell Clc formed in a crossing region of the gate line Gj 101 and the data line Dj 102. [ (103) and a storage capacitor (Cst1) (104) for maintaining the charging voltage of the liquid crystal cell (Clc) (105) for one frame.

5, each of the driving voltage supply lines VL1, VL2, ..., VLn includes first supply lines VL1a, VL2a for supplying a driving voltage to the touch sensor unit P2, ..., VLna and second supply lines VL1b, VL2b, ..., VLnb for supplying a bias voltage to the touch sensor unit P2. The touch sensor unit P2 generates a light sensing signal differently depending on whether or not a finger is touched and outputs the light sensing signal to the lead-out integrated circuit 80 through the lead-out lines ROL1, ROL2, ..., ROLm Supply.

The pixel transistors TFT1 and TFT3 are turned on in response to a scan pulse from the gate line GLj 101 by applying a data voltage supplied through the data line DLj to the pixels of the liquid crystal cell Clc 105 To an electrode (not shown). To this end, the gate electrode of the pixel transistor TFT1 103 is connected to the gate line GLj 101, the source electrode thereof is connected to the data line DLj 102 and the drain electrode thereof is connected to the liquid crystal cell Clc 105, respectively. The liquid crystal cell Clc 105 is charged with the potential difference between the data voltage and the common voltage Vcom, and the arrangement of the liquid crystal molecules is changed by the electric field formed by this potential difference to adjust the amount of light transmitted or block the light . The storage capacitor Cst1 104 is connected between the drain electrode of the pixel transistors TFT1 and TFT 103 and the second supply line VLjb.

The touch sensor unit P2 counts the contact state or time of the finger after the application of the touch enable signal TS and outputs the photocurrent i during the period when the driving voltage Vdrv is maintained at the high potential VH (S-TFT) 111 which generates a photoelectric current i and does not generate a photoelectric current i during a period in which the drive voltage Vdrv is maintained at the low electric potential VL, And a switching transistor TFT2 113 for switching the charges stored in the sensing capacitor Cst2 112 to the readout line ROLj 115. The sensing transistor Cst2 112 is connected to the sensing capacitor Cst2 112,

The gate electrode of the sensing transistor (S-TFT) 111 is connected to the second supply line (VLjb), the source electrode is connected to the first supply line (VLja), and the drain electrode is connected to the first node Respectively. A gate electrode of the sensing transistor S-TFT 111 is supplied with a bias voltage Vbias set to a voltage equal to or lower than the threshold voltage of the sensing transistor S-TFT 111 via the second supply line VLjb, The source electrode of the TFT 111 is supplied with the driving voltage Vdrv swinging between the high potential VH and the low potential VL depending on whether the finger is touched through the first supply line VLja. The sensing transistor (S-TFT) 111 performs a light sensing operation during a period in which the driving voltage Vdrv is maintained at the high potential VH corresponding to the touch of the finger.

The sensing transistor S-TFT 111 stops the light sensing operation during a period in which the driving voltage Vdrv is maintained at the low potential VL corresponding to the non-touch of the finger (non-contact) Thereby preventing deterioration of the TFT. Unlike the pixel transistors (TFT1) 103 and the switching transistors (TFT2) 113, the sensing transistor (S-TFT) 111 is not covered by the black matrix of the upper substrate. And generates the photocurrent i for a period in which the driving voltage Vdrv is maintained at the high potential VH. Even if the driving voltage Vdrv is maintained at the high potential VH, if there is no touch of the finger, the value of the photocurrent i changes, and the non-contact senses the photocurrent i.

In other words, the sensing transistor (S-TFT) 111 generates a large photocurrent (i) when it corresponds to a touch point in comparison with a case where the sensing transistor (S-TFT) 111 does not correspond to a touch point in a dark illumination environment (I) in a brighter illumination environment (outdoor environment) when compared with a touch point, compared with when the touch point is not corresponded.

Charges by the photocurrent i are stored in a sensing capacitor Cst2 112 connected between the first node N1 and the second supply line VLjb. The voltage VN1 of the first node is gradually increased by the charges stored in the sensing capacitor Cst2 112 until the switching transistors TFT2 and 113 are turned on. The voltage VN1 of the first node has a different magnitude depending on whether or not the driving voltage Vdrv corresponds to the touch point during a period in which the driving voltage Vdrv is maintained at the high potential VH. The voltage VN1 of the first node has a larger value when it corresponds to the touch point than when it does not correspond to the touch point in a dark illumination environment (indoor environment) than the backlight, and in a bright illumination environment The time corresponding to the touch point is smaller than when the touch point does not correspond to the touch point. On the other hand, the voltage VN1 of the first node is maintained at the initial value during the period in which the driving voltage Vdrv is maintained at the low potential VL.

The gate electrode of the switching transistor TFT2 113 is connected to the (j-1) th gate line Gj-1, the source electrode thereof is connected to the first node N1, the drain electrode thereof is connected to the lead- (Not shown). The switching transistor TFT2 113 is turned on in response to the scan pulse SPj-1 supplied to the (j-1) th gate line Gj-1, thereby turning on the first node voltage VN1 as the photo- And outputs it to the outline (ROLj)

6 is a schematic view showing an external button for enabling touch enable in the liquid crystal display device of the present invention.

For example, the touch sensing controller 50 shown in FIG. 3 generates a touch enable signal TS for switching a touch sensing state according to a user's instruction so that a touch signal can be sensed by receiving a user's signal from the outside , And controls the driving voltage circuit (60).

6, external signals are applied to the user from external sources. The external buttons 110 (110a, 110b) are provided outside the liquid crystal display device, and the touch enable signal TS is generated according to whether the external button is input or not. .

In this case, the external button 110 may include a first button 110a of a hook type which can selectively maintain the on or off state for a predetermined time, a second button 110b which enables a touch- Or the like.

Here, the first button 110a can adjust the voltage level applied by the user directly to the driving voltage line. The first button 110a synchronizes with the on / off input using the first button 110a of the user, Off voltage can be selectively applied. In this case, when the user gives an OFF signal, the touch enable signal TS is generated as a low signal so that the touch sensor unit does not operate (disable) and the driving voltage is applied to the low potential VL, When the on-signal is supplied through the external button, the touch enable signal TS is generated as a high signal to enable the touch sensor unit to operate normally (enable), and the drive voltage is applied to the high- The touch recognition is enabled in the sub side.

Like the second button 110b, in the case of the push type, the touch-enabled voltage is directly applied to the driving voltage line in response to the button input, and thereafter, the lead-out integrated circuit 80 The value of the driving voltage line is adjusted according to the change of the value outputted from the driving voltage line. For example, after the touch enable, if the lead-out integrated circuit 80 does not output for a predetermined time, the voltage value applied to the driving voltage line is converted into a touch-off voltage capable of being in a touch-off state and applied. It is possible to minimize the deterioration of the sensing transistor (S-TFT) since the touch sensor section P2 is not driven when the touch-off voltage value is applied.

In any of the above-described cases, when the external touch button is provided to adjust the touch sensing time, when the liquid crystal panel 10 in the initial touch-off state enters the external touch button, To a high signal. In synchronism with the rising of the touch enable signal TS, a high-level touch driving voltage is applied from the driving voltage circuit 60 to the touch sensor P2 side, Through the lead-out integrated circuit 80 through the lead-in portion P2 to detect whether or not a predetermined position is touched.

If there is no touch input in the lead-out integrated circuit 80 for a predetermined period of time after the high-level signal of the touch enable signal TS is switched, a touch control signal 70 (TC) is applied to the touch control unit 50 , The touch enable signal TS is switched to the low signal. At this time, after the touch enable signal TS is switched to the low level, in order to transmit the touch driving voltage of the high potential (VH) to the driving voltage line of the touch sensor side again, as described above, The touch enable signal TS is applied via the touch enable signal TS or the touch enable signal TS is at the low level after a predetermined time elapses, The touch enable signal TS can be changed to a high level signal after sensing the touch of the signal TS after a low signal change or by other means.

In other cases, after the drive voltage is applied to the high potential (VH) in accordance with the rise of the touch enable signal (TS) through the external button, non-contact is sensed through the lead-out integrated circuit 80, The readout integrated circuit detects a touch when there is a change in the output value by applying a drive voltage signal to the drive voltage line at a voltage level intermediate between the voltage VH and the low potential VL, The driving voltage signal changed to the high potential VH may be supplied to the driving voltage line only when the touch is sensed.

When the touch sensor unit is provided with the photosensor, the high voltage signal is continuously applied from the driving voltage side in order to drive the photosensor When a continuous high voltage signal is applied, the deterioration of the semiconductor layer of the sensing transistor for the photosensitivity increases, and the reliability of the semiconductor layer deteriorates. As a result, the touch sensing power gradually decreases with time. In particular, fatigue is accumulated in a short time due to application of a high voltage. In order to minimize such fatigue, touch detection is enabled only when there is a user's touch control instruction.

Further, for example, in the case of a small portable model such as a mobile phone, as an application of a liquid crystal display device, unintended contact is made in a pocket or a bag. In this unintended contact, So as to minimize the internal deterioration condition of the touch sensor unit.

On the other hand, for convenience of the user, it is also possible to function by sharing an external button for touch with a turn-on button or a specific function button of the liquid crystal display device.

Hereinafter, a driving method for touch sensing using the liquid crystal display device of the present invention will be described.

* First Embodiment *

7 is a flowchart showing a driving method of a liquid crystal display device according to the first embodiment of the present invention.

As shown in FIG. 7, in the method of driving a liquid crystal display according to the first embodiment of the present invention, first, an input is applied through an external button to switch the touch enable state to a touch enable state (200S). The touch enable state is obtained by applying a touch enable signal TS of a high level from the touch control unit 50 of FIG. 3 to the driving voltage supply circuit 60 when there is an external button input.

When the touch enable signal TS rises to a high level, the driving voltage supply circuit 60 supplies the driving voltage of the high potential VH to the respective driving voltage supply lines ) VLjb to drive the internal touch sensor unit P2 in the initial setting condition (205S). In this case, the supplied voltage is a phase voltage of 8 to 20V. At this time, the first driving voltage supply line VLja is a storage voltage value, and a reference voltage value of about -5 to 0V is applied. On the other hand, the reference voltage value can be continuously applied to the first driving voltage supply line irrespective of the touching contact. Even if the reference voltage value is applied to the touch sensor portion at the same time, the applied voltage value is a low value of the value irrelevant to the operation of the device, so that the deterioration of the device can be prevented.

Then, when the high potential driving voltage is applied, the lead-out integrated circuit 80 detects the presence or absence of the output according to the touch, determines whether there is no touch state for a predetermined time (210S) The lead-out integrated circuit 80 generates no output as the touch control signal TC and applies it to the touch control section 50 to switch the touch enable signal TS to the low level value. At this time, when the touch enable signal is switched to a low level, the driving voltage supply circuit outputs a driving voltage at a low potential (VL) and is applied to each driving voltage line. In this case, each touch sensor unit P2 is in the enabled state, and the liquid crystal panel is driven under the condition that internal device deterioration is prevented (220S).

If it is determined in step 210S that the absence of the touch is absent for a predetermined time, if the touch is continuously made within a predetermined time, in this case, the driving voltage value of the high potential VH Line to operate the touch sensor unit under the initial setting condition (205S).

When the liquid crystal panel is driven (220S) under the internal element deterioration preventing condition, the predetermined time t is counted from the counter (see 95 in FIG. 8) provided in the driving voltage supply circuit 60, (230S), and after a lapse of a predetermined time (t), the touch enable signal TS is switched to a high level value. At this time, the touch enable signal TS keeps the low level continuously until a predetermined time (t) elapses, so that the driving voltage of the low potential (VL) is applied and the touch sensor unit is not driven.

FIG. 8 is a detailed configuration diagram showing a circuit of the driving voltage supply circuit, and FIG. 9 is a timing chart of the touch sensing signal and the driving voltage signal of FIG.

8 and 9, the driving voltage supply circuit supplies a voltage having a high potential (VH) and a low potential (VL) according to the value of the touch enable signal TS applied through the touch controller 50 And a counter 95 for counting the elapsed time of application of the driving voltage of the low potential VL.

Here, the voltage value of the driving voltage Vdr is initially held at the low potential VL and is switched to the high potential (VH) value in synchronization with the rising of the touch enable signal TS. Next, when the non-contact state is detected from the lead-out integrated circuit, the touch control (TC) is outputted and the touch enable signal (TS) is switched to the low level.

Next, after counting whether the low level state is maintained for the predetermined time (t) set in the counter 95, the touch enable signal TS is switched back to the high level after a lapse of a predetermined time and the driving voltage Vdrv ) To a high potential (VH).

After the input from the external button, the steps 205S to 230S of Fig. 7 described above are repeatedly performed, and the driving voltage Vdrv is applied.

In the driving method according to the first embodiment of the present invention, the user can selectively select whether or not the touch is sensed through the external button, and if the touch is not detected after the driving, And a high-potential driving voltage is automatically applied again after a predetermined time elapses to drive the touch sensor unit. That is, a counter is set in the external button and the driving voltage supply circuit, and the value of the driving voltage can be switched, thereby preventing deterioration of the touch sensor unit due to continuous high-potential application.

* Second Embodiment *

FIG. 10 is a flowchart illustrating a method of driving a liquid crystal display device according to a second embodiment of the present invention. FIG. 11 shows a means for detecting contact after the touch-enable, And Fig. 12 is a detailed configuration diagram showing the driving voltage supply circuit of Fig.

As shown in FIGS. 10 to 12, in the method of driving the liquid crystal display according to the second embodiment of the present invention, first, an input is applied through an external button to switch the touch enable state to a touch enable state (100S). The touch enable state is obtained by applying a touch enable signal TS of a high level from the touch control unit 50 of FIG. 3 to the driving voltage supply circuit 60 when there is an external button input.

When the touch enable signal TS rises to a high level, the driving voltage supply circuit 60 supplies the driving voltage of the high potential VH to the respective driving voltage supply lines ) VLjb to drive the internal touch sensor unit P2 in the initial setting condition (105S). In this case, the supplied voltage is a phase voltage of 8 to 20V. At this time, the first driving voltage supply line VLja is a storage voltage value, and a reference voltage value of about -5 to 0V is applied. On the other hand, the reference voltage value can be continuously applied to the first driving voltage supply line irrespective of the touching contact. Even if the reference voltage value is applied to the touch sensor part at the non-driving time, the applied voltage value is a low value of a value irrelevant to the operation of the device, and deterioration due to device driving can be prevented.

Next, when the high potential driving voltage is applied, the lead-out integrated circuit 80 detects the presence or absence of an output according to the touch, determines whether there is no touch for a predetermined time (110S) The lead-out integrated circuit 80 generates no output as the touch control signal TC and applies it to the touch control section 50 to switch the touch enable signal TS to the low level value. At this time, when the touch enable signal is switched to a low level, the driving voltage supply circuit outputs a driving voltage at a low potential (VL) and is applied to each driving voltage line. In this case, each of the touch sensor units P2 is in an enabled state, and the liquid crystal panel is driven under the condition that internal device deterioration is prevented (120S).

If it is determined in step 110S that the absence of the touch is absent for a predetermined time, if the touch is continuously made within a predetermined time, in this case, the driving voltage value of the high potential VH is continuously set as the initial initial setting condition, Line to operate the touch sensor unit under the initial setting condition (105S).

When the liquid crystal panel is driven (120S) under the internal device deterioration preventing condition, it is determined whether there is a touch input again (130S). 11, the transparent conductive film 12 is formed on the entire back surface corresponding to the contact surface of the liquid crystal panel 10, for example, . In this case, the upper and lower polarizing plates of the liquid crystal panel 10 are formed by forming an upper polarizing plate 14 on the transparent conductive film 12 and a lower polarizing plate 16 on the lower back surface of the liquid crystal panel 10, respectively.

In this case, when the touch is detected, the finger is conductive and the transparent conductive film 12 is a conductor, the upper polarizer 14 functions as a dielectric, a capacitor C is set therebetween, It can be done by detecting a change in the amount of charge. That is, when the finger is in non-contact state and when the finger is in contact, a change in the charge amount occurs, and the change in the charge amount value is read to switch the drive voltage from the low potential (VL) to the high potential (VL).

Here, when there is no detection of touching, the internal element deterioration preventing condition, that is, the low potential (VL) applying state, which is not the initial setting condition, is maintained continuously.

In order to enable the second embodiment, the drive voltage supply circuit receives the touch enable signal TS, the touch control signal TC from the lead-out integrated circuit 80, and the charge amount sensing signal Q, And a level shifter 62 for selectively determining the potential VL or the high potential VH.

13 is a timing chart of Fig.

As shown in FIG. 13, the level change of the driving voltage Vdr in the driving method of the liquid crystal display device according to the second embodiment of the present invention is as follows.

Initially, the voltage value of the driving voltage Vdr is maintained at the low potential (VL) and is switched to the high potential (VH) value in synchronization with the rising of the touch enable signal TS.

When the non-contact state is detected from the lead-out integrated circuit, a touch control (TC) is outputted to switch the touch enable signal (TS) to a low level, and when the touch enable signal The driving voltage is also switched to the low potential VL

Then, after driving the low potential (VL), when the contact state is sensed through the contact sensing means, such as the transparent conductive film, and the charge amount change signal Q is applied, the touch enable signal is changed to high level, Thereby switching the driving voltage to the high potential (VH).

On the other hand, the above-described detection of contact at the time of low potential (VL) driving shows that the transparent conductive film is separately provided. However, depending on the case, It is possible to consider a case in which the contact state can be sensed by applying a drive voltage to the lead-out integrated circuit 80 by directly outputting a voltage change.

In the second embodiment described above, after the input from the external button, the steps 105S to 130S of Fig. 10 described above are repeatedly performed, and the drive voltage Vdrv is applied.

In the driving method according to the second embodiment of the present invention, the user can selectively select whether or not the touch is sensed through the external button, and when the touch is not performed after the driving, , And a high potential driving voltage is applied again by sensing the amount of charge after a predetermined time to drive the touch sensor unit. In other words, it is possible to set the charge quantity sensing means in the external button and the drive voltage supply circuit to switch the value of the drive voltage, thereby preventing deterioration of the touch sensor portion due to continuous high potential application.

In order to achieve the same object, the liquid crystal display device of the present invention may not be provided with the contact sensing means such as the transparent conductive film described above, but may be implemented by varying the voltage application method in the driving voltage supply circuit.

That is, in the touch sensing step after application to the external button, after the lead-out integrated circuit does not output for a predetermined time, the driving voltage value is higher than the low potential level value before application of the external button and smaller than the high potential level To allow the touch sensing to be applied at a level as high as possible. In this case, the values set by the driving voltage are three levels of low potential, high potential, and intermediate potential.

The driving method of the liquid crystal display according to the present invention is as follows.

First, in response to a user's judgment, a touch-detectable enable signal is switched from a low level to a high level to the drive voltage supply circuit.

Then, in synchronization with the above-mentioned enable signal, the driving voltage supply circuit applies a high driving voltage to the touch sensor unit.

Then, it is determined whether or not the output from the lead-out integrated circuit is the first time or longer.

Then, when the output from the lead-out integrated circuit does not pass the first time, the touch enable signal is switched to a midlevel, and the touch sensor unit in the drive voltage supply circuit prevents deterioration between the high potential and the low potential Voltage is applied.

The touch-enable signal is switched to a high level after sensing the touch by a change of the output value from the lead-out integrated circuit, and the high voltage driving voltage is applied from the driving voltage supply circuit to the touch sensor unit.

Meanwhile, in the above-described embodiments, the touch operation normally applies a drive voltage of a high potential voltage to each of the drive voltage lines as in the initial condition, detects a touch sensor unit at a predetermined position in contact with the touch panel, The touch position is detected by the application to implement display and specific functions.

In the above description, the voltage to be applied to the touch sensor unit is a high potential (8 to 20 V) and a low potential (reference voltage level, about 0 to 2 V). However, The reference voltage level Vref (about 0 to 2 V) and a low potential voltage lower than the reference voltage level may be applied. That is, the operating condition of the touch sensor unit may be such that a specific voltage of a threshold voltage is applied to the gate electrode of the sensing capacitor, a voltage difference is applied between the source electrode and the drain electrode, The voltage of the electrode, the drain electrode, and the source electrode may be applied in conformity with the reference voltage Vref.

While the present invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. Will be apparent to those of ordinary skill in the art.

1 is an equivalent circuit diagram of an active matrix type liquid crystal display device

2 is a circuit diagram of a conventional touch sensor unit

3 is a block diagram showing a liquid crystal display device of the present invention

Fig. 4 is a circuit diagram specifically showing each pixel in Fig. 3

Fig. 5 is a schematic view showing the application of a driving voltage signal to each touch sensor side of the liquid crystal panel in Fig. 3

6 is a schematic view showing an external button for enabling touch enable in the liquid crystal display device of the present invention

7 is a flowchart showing a driving method of a liquid crystal display device according to the first embodiment of the present invention

8 is a detailed configuration diagram showing a circuit of the driving voltage supply circuit

9 is a timing chart of the touch sensing signal and the driving voltage signal in Fig. 7

10 is a flowchart showing a driving method of a liquid crystal display device according to a second embodiment of the present invention

11 is a schematic view showing a means for detecting whether or not a touch is made after deteriorated driving in accordance with lead-out detection after touch enable.

Fig. 12 is a detailed configuration diagram showing the driving voltage supply circuit of Fig. 10

13 is a timing chart

Description of the Related Art [0002]

10: liquid crystal panel 20: data driving circuit

30: Gate driving circuit 40: Timing controller

50: touch sensing control unit 60: driving voltage supply circuit

62: Level shifter 95: Counter

70: Backlight unit 80: Lead-out integrated circuit

101: gate line 102: data line

103: pixel transistor 105: liquid crystal capacitor

111: sensing transistor 112: sensing capacitor

113: switching transistor 115: lead-out line

110: external button 150: liquid crystal display with built-in touch sensor

Claims (11)

A liquid crystal panel having a plurality of gate lines and data lines crossing each other to define a pixel region, a pixel transistor in the pixel regions, a touch sensor portion, and a lead out line connected to an output terminal of the touch sensor portion; A driving circuit for supplying driving signals to the gate lines and the data lines, respectively; A timing controller for controlling a driving timing of the driving circuit; A backlight unit for irradiating light to the back surface of the liquid crystal panel; And A lead-out integrated circuit to which lead-out lines of the touch sensor unit are commonly connected; A touch sensing control unit for generating a touch enable signal for switching to a touch sensing state according to a user's instruction and an output of the lead-out integrated circuit; And And a driving voltage supply circuit for supplying a high potential voltage and a low potential voltage, which are necessary for driving the touch sensor section in the pixel region, to a different voltage level in accordance with the touch enable signal. The method according to claim 1, Wherein the instruction of the user is made by an external button formed outside the liquid crystal panel. The method according to claim 1, Wherein the switching of the driving voltage supply circuit from the high potential voltage to the low potential voltage is performed when the output value from the lead-out integrated circuit does not change for a predetermined period of time. The method according to claim 1, Wherein the driving voltage supply circuit further comprises a counter for counting a time duration of the low potential voltage. The method according to claim 1, Wherein a transparent conductive film is formed on the entire surface of the liquid crystal panel corresponding to the contact surface of the liquid crystal panel, the amount of charge being changed according to a touch sensation. A liquid crystal display device comprising: a liquid crystal panel having a plurality of pixel regions, each pixel region including a pixel transistor and having a plurality of pixel regions, each pixel region having a photo-sensitive touch sensor; And a lead-out integrated circuit connected to the touch sensor for outputting, amplifying and sensing a photocurrent in a touch region, the lead-out integrated circuit comprising: Switching from a low level to a high level and supplying a touch-detectable enable signal to the driving voltage supply circuit according to a user's judgment; Applying a high drive voltage to the touch sensor unit in the drive voltage supply circuit in synchronization with the enable signal; Determining whether the output from the readout integrated circuit is greater than a first time; Switching the touch enable signal to a low level when an output from the lead-out integrated circuit does not pass a first time, and applying a driving voltage of a low potential to the touch sensor unit in the driving voltage supply circuit; And Counting a second time after the low level change and supplying the touch enable signal to a high level after a lapse of a second time and applying a high potential driving voltage to the touch sensor unit in the driving voltage supply circuit And a driving method of the liquid crystal display device. A liquid crystal display device comprising: a liquid crystal panel having a plurality of pixel regions, each pixel region including a pixel transistor and having a plurality of pixel regions, each pixel region having a photo-sensitive touch sensor; A lead-out integrated circuit connected to the touch sensor for outputting, amplifying and sensing a photocurrent of a touch region; A method of driving a liquid crystal display including a touch sensing means, Supplying a touch-sensitive enable signal to the driving voltage supply circuit from a low level to a high level according to a user's judgment; Applying a high drive voltage to the touch sensor unit in the drive voltage supply circuit in synchronization with the enable signal; Determining whether the output from the lead-out integrated circuit does not change for a first time or longer; Switching the touch enable signal to a low level when an output from the lead-out integrated circuit does not pass a first time, and applying a driving voltage of a low potential to the touch sensor unit in the driving voltage supply circuit; And a step of switching the touch enable signal to a high level through the touch sensing means and applying a high potential driving voltage to the touch sensor unit in the driving voltage supply circuit. A method of driving a display device. 8. The method according to claim 6 or 7, Wherein the judgment by the user is made by pressing an external button with an external button on the liquid crystal panel. The method according to claim 6, And a counter for counting a second time to the driving voltage supply circuit. 8. The method of claim 7, Wherein the contact sensing means is a transparent conductive film attached to the contact surface side of the liquid crystal panel. 8. The method according to claim 6 or 7, In the step of determining whether the output from the lead-out integrated circuit does not change for a first time or longer, Wherein when the output from the lead-out integrated circuit is within a first time period, the touch enable signal is maintained at a high level, and the driving voltage supply circuit applies a high-potential driving voltage to the touch sensor unit. A method of driving a device.

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