KR20100005854A - Liquid crystal display device and method for driving the same - Google Patents

Abstract

PURPOSE: A liquid crystal display device and a method for driving the same are provided to the deterioration of a sensing transistor according to high voltage supply by controlling voltage to the sensing transistor. CONSTITUTION: A timing controller(40) controls a drive timing of a gate driving circuit(30) and a data driving circuit(20). A touch sensing controller(50) generates a touch enable signal converted into the touch-sensitive state by a user's command. A drive voltage supply circuit(60) supplies a touch driving voltage and a touch off voltage to drive voltage supply lines required for the driving of the touch sensor inside a pixel according to a touch enable signal.

Description

Liquid Crystal Display Device and Method for Driving the Same}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display, and more particularly, to a liquid crystal display and a driving method thereof in which a deterioration of the touch sensing element is minimized by adjusting the application of a driving voltage when a touch sensor is provided inside the liquid crystal panel.

In recent years, as the information age has entered, the display field for visually expressing electrical information signals has been rapidly developed, and various flat panel display devices having excellent performance of thinning, light weight, and low power consumption have been developed. Flat Display Device has been developed and is rapidly replacing the existing Cathode Ray Tube (CRT).

Specific examples of such a flat panel display device include a liquid crystal display device (LCD), a plasma display panel device (PDP), a field emission display device (FED), and an electroluminescent display device. (Electro luminescence Display Device: ELD) and the like, these are commonly used as an essential component of a flat panel display panel that implements an image, a flat panel display panel has a pair of light emitting or polarizing material layer in between It has a configuration in which a transparent insulating substrate is faced and bonded together.

The dual liquid crystal display displays an image by adjusting the light transmittance of the liquid crystal using an electric field. To this end, the image display device includes a display panel having a liquid crystal cell, a backlight unit for irradiating light to the display panel, and a driving circuit for driving the liquid crystal cell.

The display panel is formed such that a plurality of unit pixel regions are defined by crossing a plurality of gate lines and a plurality of data lines. In this case, each pixel area 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 a gate line and a data line, a thin film transistor formed of a switch element at each intersection of the gate lines and the data lines, a pixel electrode formed of a liquid crystal cell and connected to the thin film transistor, and the like. It consists of the applied alignment film. The gate lines and the data lines receive signals from the driving circuits through the respective pad parts.

The thin film transistor supplies the pixel voltage signal supplied to the data line to the pixel electrode in response to the scan signal supplied to the gate line.

In addition, the color filter array substrate is coated on the 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, and the like. It consists of the alignment film which becomes.

The thin film transistor substrate and the color filter array substrate manufactured separately are aligned and then bonded to each other, and then the liquid crystal is injected and encapsulated.

The liquid crystal display device formed as described above has recently formed an optical sensor inside the display panel to control the backlight unit according to the brightness of the external light, and to attach the touch panel to the outside of the display panel to form a touch panel inside the display panel. Efforts to increase are increasing.

Hereinafter, a liquid crystal display according to the related art will be described with reference to the accompanying drawings.

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

As a switching element used in an active matrix type liquid crystal display device, a thin film transistor (hereinafter referred to as TFT) is mainly used as shown in FIG. 1.

Referring to FIG. 1, an active matrix type liquid crystal display converts digital video data into an analog data voltage based on a gamma reference voltage and supplies it to the data line DL and simultaneously supplies scan pulses to the gate line GL. The data voltage is charged in the liquid crystal cell Clc. For this purpose, the gate electrode of the TFT is connected to the gate line GL, the source electrode 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. It is connected to one electrode. The common voltage Vcom is supplied to the common electrode of the liquid crystal cell Clc. The storage capacitor Cst1 charges a data voltage applied from the data line DL when the TFT is turned on to maintain a constant voltage of the liquid crystal cell Clc. When the 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 so that the voltage on the data line DL is applied to the pixel electrode of the liquid crystal cell Clc. Supply. At this time, the liquid crystal molecules of the liquid crystal cell Clc modulate the incident light by changing the arrangement by the electric field between the pixel electrode and the common electrode.

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

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

However, such a liquid crystal display device causes various problems such as a cost increase due to a touch screen panel, a decrease in yield due to a process of adhering the touch screen panel to a liquid crystal panel, a decrease in brightness and an increase in thickness of the liquid crystal panel.

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

In order to solve the above-mentioned problems of the touch panel described above, instead of the touch screen panel, a touch for forming a touch sensor unit including a sensing transistor inside the liquid crystal cell Clc of the liquid crystal display device as shown in FIG. Touch panel in-cell method has been proposed. The touch sensor unit senses the output of the charges stored in the sensing transistor Cst2, which stores the charges generated by the photocurrent i, the sensing transistor that generates the photocurrent i differently according to a change in the amount of light incident from the outside, and the sensing capacitor Cst2. And a switching transistor for switching. The bias voltage Vbias set to a voltage below its threshold voltage is supplied to the gate electrode of the sensing transistor. In the light sensor environment (indoor environment) that is darker than the backlight, the touch sensor unit has a larger light current of the sensing transistor corresponding to the touched part than the light current of the sensing transistor corresponding to the non-touched part, but is brighter than the backlight (outdoor environment). In this case, the photocurrent of the sensing transistor corresponding to the touched portion is smaller than the photocurrent of the sensing transistor corresponding to the non-touched portion, thereby generating different photodetection signals in the touched or untouched portion. The liquid crystal display may detect contact position information of a user's finger or the like based on the light detection signal of the touch sensor unit.

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

First, for a photosensitive operation, a sensing transistor built in a conventional touch panel, a cell type liquid crystal display device, needs to be continuously supplied with a high potential DC driving voltage (Vdrv) through its drain electrode, so that it can be easily driven for a long time. There is a problem of deterioration. Such deterioration of the sensing transistor lowers the output characteristics of the touch sensor unit, causing an error in the light sensing signal output, and thus deteriorates the reliability of the touch sensor unit.

Second, when the sensing transistor is deteriorated, the touch sensor unit may output a detection signal that is not touched even when the user's finger or the like is touched on the liquid crystal cell in which the touch transistor is formed. There is a possibility of outputting the touched detection signal even if it is not touched. Since the touch panel, a cell-type liquid crystal display, senses a touch point only with a relative difference of photocurrent flowing through the sensing transistors, when the sensing transistor deteriorates, it is impossible to accurately detect whether the touch is actually performed. For example, in a strong illuminance environment such as the outside, even if a shadow is generated by external light when a finger or the like is not touched by the liquid crystal panel, there is a problem in that it is mistaken as a touch as if actually touched.

The present invention has been made to solve the above problems, and when the touch sensor is provided inside the liquid crystal panel, the present invention provides a liquid crystal display device and a method of driving the same, which minimize the deterioration of the touch sensing element by adjusting the application of a driving voltage. There is a purpose.

According to an exemplary embodiment of the present invention, a liquid crystal display device includes a plurality of gate lines and a data line crossing each other to define a pixel region, a pixel transistor in the pixel regions, a touch sensor unit, and the touch sensor. A liquid crystal panel having a lead out line connected to a negative output terminal, a driving circuit for supplying driving signals to the gate lines and data lines, a timing controller for controlling driving timing of the driving circuit, A backlight unit for irradiating light to the rear surface, a lead-out integrated circuit to which the lead-out line of the touch sensor unit is commonly connected, and a touch-in for switching to a touch sensing state according to a user's instruction and output of the lead-out integrated circuit. A touch sensing controller generating an enable signal and the pixel according to the touch 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 may be performed when the output value from the readout integrated circuit does not change for a predetermined time.

The driving voltage supply circuit may further include a counter for counting a time period during which the low potential voltage is maintained.

In some cases, a transparent conductive film may be further formed on the front surface corresponding to the contact surface of the liquid crystal panel, the charge amount of which changes according to touch sensing.

In addition, the driving method of the liquid crystal display device of the present invention for achieving the same object is provided with a plurality of pixel regions, each pixel region includes a pixel transistor, and some pixel regions with a light sensor capable of detecting light. A liquid crystal panel; and a driving voltage supply circuit configured to generate a driving voltage signal to control whether the touch sensor is driven or not; and a readout integrated circuit connected to the touch sensor to output and amplify an optical current of a touch region. A driving method of a liquid crystal display device comprising: providing a touch-sensing enable signal from a low level to a high level and supplying the touch-sensitive enable signal to the driving voltage supply circuit according to a user's judgment; and the enable signal Applying a high potential driving voltage from the driving voltage supply circuit to a touch sensor unit in synchronization with the; Determining whether the output is unchanged for at least a first time from the readout integrated circuit; when the output is not elapsed from the readout integrated circuit for a first time, switching the touch enable signal to a low level; Applying a low potential driving voltage from the driving voltage supply circuit to the touch sensor unit; And counting a second time after the low level switching, supplying the touch enable signal to a high level after a second time elapses, and applying a high potential driving voltage from the touch driving voltage supply circuit to the touch sensor unit. It is characterized by comprising;

In addition, the driving method of the liquid crystal display device of the present invention for achieving the same object is provided with a plurality of pixel regions, each pixel region has a pixel transistor, and some pixel regions are provided with a light sensor capable of sensing light. A liquid crystal panel; and a driving voltage supply circuit configured to generate a driving voltage signal to control whether the touch sensor is driven or not; and a readout integrated circuit connected to the touch sensor to output and amplify an optical current of a touch region. ; A driving method of a liquid crystal display device comprising a touch sensing means, the method comprising: supplying a touch senseable enable signal from a low level to a high level to the driving voltage supply circuit according to a user's judgment; Applying a high potential driving voltage from the driving voltage supply circuit to a touch sensor unit in synchronization with a signal; determining whether an output from the readout integrated circuit has changed for at least a first time; and the readout integration Switching the touch enable signal to a low level when there is no output from the circuit after a first time, and applying a low potential driving voltage from the driving voltage supply circuit to the touch sensor unit; and the touch sensing Means, after touch sensing, switches the touch enable signal to a high level and the touch drive voltage Another feature is that the step of applying a high potential driving voltage to the touch sensor unit in the circuit. The driving voltage supply circuit may further include a counter for counting a second time. The touch sensing means may be formed of a transparent conductive film attached to the contact surface side of the liquid crystal panel.

In the above method, the user's judgment is made by pressing an external button by providing an external button on the liquid crystal panel.

And determining whether there is no output from the readout integrated circuit for a first time or more, if the output from the readout integrated circuit is within a first time, maintaining the touch enable signal at a high level and driving the drive. In the voltage supply circuit, a high potential driving voltage is applied to the touch sensor unit.

As described above, the liquid crystal display and the driving method thereof according to the present invention have the following effects.

First, the liquid crystal display device and the driving method thereof according to the present invention include an external button, and perform touch only when the user instructs the user, and when used in a small application such as a mobile phone, The malfunction can be prevented from occurring.

Second, it is possible to selectively apply a voltage according to the user's instructions, if there is no user's instructions, by applying a high voltage to the touch sensor unit, in particular the sensing transistor side, the photosensitive transistor (sensing transistor) is severely degraded due to high voltage application ) Deterioration can be minimized. Particularly, in the case of the photosensitive transistor, amorphous silicon included in the transistor has a severe increase in temperature when the high voltage is continuously applied, thereby deteriorating accordingly.

Third, when driving, when there is no output value calculated according to the output value from the readout integrated circuit, a low potential value is applied to the driving voltage supply circuit side to prevent high potential driving at the time of metering, thereby preventing deterioration. Can be tried.

Fourth, after application of the low potential at the time of metric measurement, a touch is sensed through a separate touch sensing means, and the driving voltage is switched to high potential, or after the specific time set in the counter is provided with a counter, it is switched back to a high potential value. Touch sensing can be performed without malfunction.

Fifth, the liquid crystal panel may include an in-cell type touch panel, which may include an in-cell type touch panel, which is formed in the liquid crystal panel together with an array of thin film transistors. By minimizing deterioration of the touch sensor unit, it is possible to improve the reliability of the liquid crystal panel having a touch sensing function even for a long time driving.

Hereinafter, a liquid crystal display 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 illustrating a liquid crystal display of the present invention, FIG. 4 is a circuit diagram showing in detail each pixel of FIG. 3, and FIG. 5 is a driving voltage signal at each touch sensor side of the liquid crystal panel in FIG. 3. Schematic diagram showing authorization.

As shown in 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 the plurality of driving voltage supply lines VL1, VL2, ..., Vn-1, VLn cross each other and have a touch sensor unit together with a pixel transistor for driving the pixel at an intersection thereof. The liquid crystal panel 10 where the Ps are disposed, the data driving circuit 20 for supplying a data voltage to the data lines D1, D2,..., Dm-1, and Dm, and the gate lines. Timing for controlling the driving timing of the gate driving circuit 30 for supplying scan pulses to the G0, G1, ..., Gn-1, Gn, and the data driving circuit 20 and the gate driving circuit 30. The controller 40, the touch sensing controller 50 generating a touch enable signal TS for switching to a touch sensing state according to a user's instruction, and the touch in the pixel P according to the touch enable signal TS. Sensor part drive A driving voltage supply circuit 60 for supplying the driving voltage supply lines VL1, VL2,..., VLn-1, VLn with different touch levels to the touch driving voltage and the touch-off voltage, The backlight unit 70 for irradiating light to the rear surface of the liquid crystal panel 10 and the read-out lines ROL1, ROL2,..., ROLm of the liquid crystal panel 10 are commonly used. The lead-out integrated circuit 80 is connected.

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

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

On the lower substrate 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. Multiple driving voltage supply lines VL1, VL2, ..., VLn parallel to the gate lines G0, G1, G2, ..., Gn, gate lines G0, G1, G2, .. ..., Gn) and a plurality of lead out lines ROL1, RO2, ..., ROLm orthogonal to the driving voltage supply lines VL1, VL2, ..., VLn are formed. Here, the plurality of driving voltage supply lines and the lead-out lines may be formed by numbers corresponding to the number of gate lines and the number of data lines, respectively, when the touch sensor unit is formed in every pixel area. When formed in every n pixel areas, the driving voltage supply line and the lead-out line may be selectively formed corresponding to the position of the touch sensor unit.

As illustrated in FIG. 4, the pixel circuit P1 is formed at the intersection of the data lines D1, D2,..., And Dm and the gate lines G1, G2,..., Gn. ) Is formed, and the touch sensor unit P2 is formed at the intersection of the driving voltage supply lines VL1, VL2, ..., VLn and the lead out lines ROL1, ROL2, ..., ROLm. do.

The data driving circuit 20 receives the digital video data R, G, and B from the gamma reference voltage generator (not shown) in response to the data control signal DDC from the timing controller 40. The analog gamma compensation voltage is converted into an analog gamma compensation voltage based on the GMA, and the analog gamma compensation voltage is supplied 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 the gate control signal GDC from the timing controller 40, and sequentially supplies the scan pulse to the gate lines G1 to Gn to supply a data voltage. The horizontal line of the liquid crystal panel 10 is selected.

The timing controller 40 rearranges the digital video data R, G, and B from the system (not shown) to the liquid crystal panel 10 to supply the data driving circuit 20. In addition, the timing controller 40 uses the timing control signals Vsync, Hsync, DCLK, and DE from the system to control the data driving circuit 20 and the gate driving circuit 30. ) Generates a gate control signal GDC for controlling () and a readout control signal RDC for controlling the readout integrated circuit 80.

The touch sensing controller 50 operates by receiving an input of an external button or a touch control signal TC from the readout integrated circuit 80 to control the driving voltage supply circuit 60. Outputs TS).

Here, the touch enable signal TS is generated according to the application of an external button or the presence or absence of an output value of the readout integrated circuit, and the touch enable signal TS is swinged from 0 V to 3.3 V. Logic) level signal.

In addition, the driving voltage supply circuit 60 includes a level shifter therein. Using such a level shifter, the driving voltage supply circuit 60 level shifts the TTL level touch enable signal TS in accordance with the driving of the touch sensor unit P2 in the pixel region P, and the level shifting. As a result, the driving voltage Vdrv generated between the high potential VH and the low potential Vl is generated to supply the first of the driving voltage supply lines VL1 to VLn as shown in FIGS. 4 and 5. Supply to lines VL1a, VL2a, ..., VLna. Here, the touch sensor unit P2 performs the light sensing operation during the period in which the driving voltage Vdrv is generated at the high potential VH in response to the touch-on signal, and touch-off. In response to the signal, the touch sensor unit P2 stops the light sensing operation during the period in which the driving voltage Vdrv is generated at the low potential VL. Although not shown, the driving voltage supply circuit 60 generates a bias voltage and supplies the bias voltage to the second supply lines VL1b to VLnb of the driving voltage supply lines VL1 to VLn.

Meanwhile, the backlight unit 70 includes a plurality of lamps installed to overlap the liquid crystal panel 116 on the rear surface of the liquid crystal panel 10. The lamp used in the backlight unit 70 may be any one of a cold cathode fluorescent lamp (CCFL), an external electrode fluorescent lamp (EEFL), and a hot cathode fluorescent lamp (HCFL). have. The lamps irradiate light onto the rear surface of the liquid crystal panel 10 by driving an inverter (not shown). Meanwhile, the backlight unit 70 may include 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,..., And RLOm of the liquid crystal panel 10, and the lead-out lines ROL1, ROL2, ... The optical sensing signal from .., RLOm is converted into a digital signal and supplied to a system (not shown). The system performs a processor process of touch recognition and coordinate calculation through a touch algorithm, and reflects the result on the liquid crystal panel 10 again.

On the other hand, a black matrix is formed on the upper substrate of the liquid crystal panel 10 to cover the boundary between the pixels P. The common electrode supplied with the common voltage facing the pixel electrode with the liquid crystal layer interposed therebetween is formed on the upper substrate in vertical electric field modes such as twisted nematc (TN) mode and vertical alignment (VA) mode, and in plane switching (IPS). In a horizontal electric field mode such as a mode and a fringe field switching (FFS) mode, the substrate is formed on the lower substrate.

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

Referring to FIG. 4, the pixel P includes the pixel circuit P1 formed at the intersection of the j-th gate line Gj and the j-th data line Dj, the j-th first supply line VLja and j. The touch sensor unit P2 is formed at an intersection of the second second supply line VLjb and the jth 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 is formed at the intersection of the liquid crystal cell Clc, the gate line Gj 101, and the data line Dj 102, and the pixel transistor TFT1 for driving the liquid crystal cell Clc. And a storage capacitor (Cst1) 104 for maintaining the charging voltage of the liquid crystal cell (Clc) 105 for one frame.

In addition, referring to FIG. 5, each of the driving voltage supply lines VL1, VL2,..., VLn may include first supply lines VL1a and 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 an optical sensing signal differently depending on whether a finger is touched, and transmits the optical sensing signal to the readout integrated circuit 80 through the readout lines ROL1, ROL2,..., ROLm. Supply.

The pixel transistors TFT1 and 103 may receive data voltages supplied through the data lines DLj 102 in response to the scan pulses from the gate lines GLj 101 and the pixels of the liquid crystal cell Clc 105. Supply to an electrode (not shown). For this purpose, the gate electrode of the pixel transistor TFT1 103 is connected to the gate line GLj 101, the source electrode is connected to the data line DLj 102, and the drain electrode is connected to the liquid crystal cell Clc ( And a pixel electrode of 105. 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 the potential difference to control the amount of light transmitted or to block the light. . The storage capacitor Cst1 104 is connected between the drain electrode of the pixel transistor TFT1 103 and the second supply line VLjb.

After the touch enable signal TS is applied, the touch sensor unit P2 counts the contact state or time of the finger, so that the photocurrent i is maintained during the period in which the driving voltage Vdrv is maintained at the high potential VH. ) And a sensing transistor (S-TFT) 111 that does not generate a photocurrent i and a charge stored by the photocurrent i during a period in which the driving voltage Vdrv is maintained at a low potential VL. The sensing capacitor (Cst2) 112 and the switching transistor (TFT2) 113 for switching the charges stored in the sensing capacitor (Cst2) 112 to the read out line (ROLj) 115.

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 N1. Connected. A bias voltage Vbias set to a voltage equal to or lower than its threshold voltage is supplied to the gate electrode of the sensing transistor S-TFT 111, and the sensing transistor S-TFT is provided. The source electrode of 111 is supplied with a driving voltage Vdrv that swings between the high potential VH and the low potential VL depending on whether the finger touches 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 in response to a touch of a finger.

In addition, the sensing transistor S-TFT 111 stops the light sensing operation during the period in which the driving voltage Vdrv is maintained at the low potential VL in response to the non-touch (non-contact) of the finger, thereby continuing the sensing operation. Prevent deterioration of the TFT. Since the sensing transistor S-TFT 111 is not covered by the black matrix of the upper substrate unlike the pixel transistors TFT1 and 103, the sensing transistor S-TFT 111 responds to light incident from the outside. The photocurrent i is generated during the period in which the driving voltage Vdrv is maintained at the high potential VH. Even when the driving voltage Vdrv is maintained at the high potential VH, if there is no touch of the finger, the photocurrent i value changes, and it is detected as a non-contact.

In other words, the sensing transistor (S-TFT) 111 generates a large photocurrent i when corresponding to the touch point compared to when it does not correspond to the touch point in an illuminance environment (indoor environment) that is darker than the backlight. In a brighter illuminance environment (outdoor environment), a smaller photocurrent i is generated when corresponding to the touch point than when not corresponding to the touch point.

Charges by the photocurrent i are stored in the 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 until the switching transistor TFT2 113 is turned on by the charges stored in the sensing capacitor Cst2 112. The voltage VN1 of the first node has a different size depending on whether the driving voltage Vdrv corresponds to the touch point during the 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 corresponding to the touch point than when it does not correspond to the touch point in an illuminance environment (indoor environment) that is darker than the backlight, and in an illuminance environment (outdoor environment) that is brighter than the backlight. The time corresponding to the touch point has a smaller value than the time corresponding to the touch point. Meanwhile, the voltage VN1 of the first node is maintained at an 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 is connected to the first node N1, and the drain electrode is connected to the lead out line ROLj. Is connected to 115. 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 to read the first node voltage VN1 as a light sensing signal. Output to the outline ROLj 115.

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

For example, the touch sensing controller 50 of FIG. 3 may generate a touch enable signal TS that switches to a touch sensing state according to a user's instruction so that touch sensing is possible by receiving a user's signal from the outside. The driving voltage circuit 60 is controlled.

Here, the user's signal is externally provided with external buttons 110 (110a and 110b) on the outside of the liquid crystal display as shown in FIG. 6, and according to whether the external button is input, the touch enable signal TS Change the value of.

In this case, the external button 110 may have a hook-type first button 110a that can be selectively maintained on or off for a predetermined time, and a second button 110b that enables touch enable initial control in a push type. It can be in either form.

Here, the first button 110a may adjust a voltage level applied by the user directly to the driving voltage line, and the touch driving voltage and the touch may be synchronized in accordance with an on / off input using the first button 110a of the user. The off voltage can optionally be 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 (disabled), and a driving voltage is applied to the low potential VL. When the ON signal is applied through an external button, the touch enable signal TS is generated as a high signal so that the touch sensor unit operates normally (enables), and a driving voltage is applied to the high potential VH to allow the touch sensor to operate. Touch recognition is possible on the secondary side.

In the case of the push type, as in the second button 110b, the touch driving voltage is directly applied to the driving voltage line according to the button input, and then the read-out integrated circuit 80 is separately applied. Adjust the value of the driving voltage line according to the change of the value output from). For example, after the touch enable, if there is no output from the readout integrated circuit 80 for a predetermined time, the voltage value applied to the driving voltage line is converted into a touch-off voltage capable of a touch-off state and applied. Since the touch sensor unit P2 is not driven when the touch-off voltage value is applied, deterioration of the sensing transistor S-TFT may be minimized.

In any of the above cases, when the touch sensing point is adjusted by providing an external button, when the liquid crystal panel 10 which is in the touch-off state from the initial state is inputted with an external button, the touch enable signal TS Switch to the high signal. In synchronization with the rising of the touch enable signal TS, a touch driving voltage having a high level is applied from the driving voltage circuit 60 to the touch sensor unit P2, and thus the touch sensor. The readout integrated circuit 80 detects whether a predetermined position is touched through the unit P2.

After switching the high signal of the touch enable signal TS, if there is no touch input in the readout integrated circuit 80 for a predetermined time or more, the touch control signal 70 (TC) is applied to the touch controller 50. , Converts the touch enable signal TS to a low signal. At this time, after the touch enable signal TS is switched to the low level, in order to transfer the touch driving voltage of the high potential VH to the driving voltage line of the touch sensor unit again, as described above, the external button again. The touch enable signal TS is applied through the touch enable signal TS, or the touch drive voltage of the high potential VH is applied after a predetermined time elapses while the touch enable signal TS is at a low level, or the touch enable signal is enabled. The touch enable signal TS may be changed to a high level signal after detecting the touch signal by switching the low signal of the signal TS or by a separate means.

In other cases, after applying the driving voltage to the high potential VH according to the rising of the touch enable signal TS through the external button, and detecting the non-contact through the readout integrated circuit 80, By applying a driving voltage signal to the driving voltage line under a voltage level of a medium level between VH and the low potential VL, when a readout integrated circuit has a change in output value, it detects whether or not a touch is made. Only when the touch is sensed, the driving voltage signal may be supplied to the driving voltage line again with a high potential (VH).

As such, the reason why the touch button of the user is provided by the external button is that the high voltage signal is continuously applied from the driving voltage side to drive the photo sensor when the touch sensor unit includes the photo sensor. When a continuous high voltage signal is applied, the semiconductor layer deterioration of the sensing transistor for photo-sensing becomes large, which causes the reliability to deteriorate and the touch sensing power gradually decreases with time. In particular, fatigue is accumulated in a short time due to the application of high voltage, and in order to minimize such fatigue, touch sensing is enabled only when a user's touch control instruction is given.

In addition, for example, as an application of the liquid crystal display device, in the case of a small portable model such as a mobile phone, an unintended contact is made in a pocket or a bag, and the touch sensor unit P2 is driven to the unintentional contact. This is to prevent the internal deterioration condition of the touch sensor unit.

Meanwhile, for convenience of the user, it may be possible to share an external button for touch with a turn-on button or a specific function button of the liquid crystal display.

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

First Embodiment

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

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

When the rising of the touch enable signal TS occurs at a high level, the driving voltage supply circuit 60 converts the driving voltage of the high potential VH into the respective driving voltage supply lines (second driving voltage supply line). (VLjb) to drive the internal touch sensor unit P2 under the initial setting condition (205S). In this case, the voltage supplied is a phase voltage of 8-20V. In this case, the first driving voltage supply line VLja is a storage voltage value, and a reference voltage value of about −5 to 0V is applied. Meanwhile, a reference voltage value may be continuously applied to the first driving voltage supply line regardless of touch contact. Although the reference voltage value is applied when the touch sensor unit is not driven, the deterioration of the device can be prevented because the applied voltage value is a low potential value having a value unrelated to the operation of the device.

Subsequently, when the high potential driving voltage is applied, the output of the read-out integrated circuit 80 detects the presence or absence of an output according to the touch, and determines whether there is no touch for a predetermined time (210S). If continues, the readout integrated circuit 80 generates no output as a touch control signal TC and applies it to the touch controller 50, thereby converting the touch enable signal TS to a low level value. At this time, when the touch enable signal is switched to the low level, the driving voltage value is output at the low potential VL from the driving voltage supply circuit and is applied to each driving voltage line. In this case, each of the touch sensor units P2 is enabled, thereby driving the liquid crystal panel under the condition that the internal element deterioration is prevented (220S).

When it is determined whether there is no touch for a predetermined time (210S), and if there is a continuous touch within a predetermined time, in this case, the driving voltage value of the high potential (VH) is continuously changed to the original initial setting condition for each driving voltage. When applied to a line, the touch sensor unit is operated in an initial setting condition (205S).

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

8 is a detailed configuration diagram illustrating a circuit of a driving voltage supply circuit, and FIG. 9 is a timing diagram of a touch sensing signal and a driving voltage signal of FIG. 7.

As shown in FIGS. 8 and 9, the driving voltage supply circuit has 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. The level shifter 162 for switching the voltage and the counter 95 for counting the elapsed time of applying the driving voltage of the low potential VL are included.

Here, the voltage value of the driving voltage Vdr is initially maintained at the low potential VL value, and is converted to the high potential VH value in synchronization with the rising of the touch enable signal TS. Subsequently, when a non-contact state is detected from the readout integrated circuit, the touch control TC is output, and the touch enable signal TS is switched to the low level.

Subsequently, after counting whether the low level state is maintained at the predetermined time t set in the counter 95, the touch enable signal TS is switched to the high level again after a predetermined time elapses, and thus the driving voltage Vdrv. ) To high potential (VH).

After input from the external button, the above-described steps 205S to 230S in FIG. 7 occur repeatedly to apply the driving voltage Vdrv.

In the driving method according to the first embodiment of the present invention, the user can first select and designate whether the touch is sensed through an external button, and if there is no touch after driving, the driving method is switched to a condition for preventing deterioration. After a predetermined time, the touch sensor unit is automatically driven by applying a high potential driving voltage again. That is, by setting a counter to the external button and the driving voltage supply circuit, 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 according to a second exemplary embodiment of the present invention, and FIG. 11 illustrates a means for detecting contact after deterioration driving according to lead-out detection after touch enable. 12 is a schematic diagram illustrating a detailed driving voltage supply circuit of FIG. 10.

10 to 12, the driving method of the liquid crystal display according to the second exemplary embodiment of the present invention first applies an input through an external button to switch to a touch enable state capable of touch sensing (100S). The touch enable state is performed by applying a high level touch enable signal TS to the driving voltage supply circuit 60 from the touch controller 50 of FIG. 3 when there is an external button input.

When the rising of the touch enable signal TS occurs at a high level, the driving voltage supply circuit 60 converts the driving voltage of the high potential VH into the respective driving voltage supply lines (second driving voltage supply line). (VLjb) to drive the internal touch sensor unit P2 under the initial setting condition (105S). In this case, the voltage supplied is a phase voltage of 8-20V. In this case, the first driving voltage supply line VLja is a storage voltage value, and a reference voltage value of about −5 to 0V is applied. Meanwhile, a reference voltage value may be continuously applied to the first driving voltage supply line regardless of touch contact. Although the reference voltage value is applied when the touch sensor unit is not driven, since the applied voltage value is a low potential value having a value unrelated to the operation of the device, deterioration due to device driving can be prevented.

Subsequently, when the high potential driving voltage is applied, the output of the read-out integrated circuit 80 detects the presence or absence of a touch, and determines whether there is no touch for a predetermined time (110S). If continues, the readout integrated circuit 80 generates no output as a touch control signal TC and applies it to the touch controller 50, thereby converting the touch enable signal TS to a low level value. At this time, when the touch enable signal is switched to the low level, the driving voltage value is output at the low potential VL from the driving voltage supply circuit and is applied to each driving voltage line. In this case, each touch sensor unit P2 is enabled, and thus the liquid crystal panel is driven under the condition that the internal element deterioration is prevented (120S).

When it is determined whether there is no touch for a predetermined time (110S), and if there is a continuous touch within a predetermined time, in this case, the driving voltage value of the high potential (VH) is continuously set to the original initial setting condition. Applying to the line, the touch sensor unit is operated under the initial setting condition (105S).

Subsequently, when the liquid crystal panel is driven 120S under the internal element deterioration preventing condition, it is determined whether there is a touch input again (130S). In this case, determining the presence or absence of the touch input is performed by forming the transparent conductive film 12 on the back surface corresponding to the contact surface of the liquid crystal panel 10, for example, as shown in FIG. In this case, upper and lower polarizing plates of the liquid crystal panel 10 are formed by forming an upper polarizing plate 14 and a lower polarizing plate 16 on the lower rear surface of the liquid crystal panel 10 on the transparent conductive film 12, respectively.

In this case, when the touch is conducted, the upper polarizing plate 14 functions as a dielectric, and the capacitor C is set therebetween when the finger conducts the finger and the transparent conductive film 12 is a conductor. This can be done by detecting a change in charge amount. That is, a change in charge amount will occur when switching from non-contact to touch of a finger, and the change of the charge amount value is read to convert the driving voltage from low potential VL to high potential VL.

In this case, when there is no detection of whether the touch is performed, the internal device deterioration prevention condition, that is, the low potential VL applied state is maintained continuously instead of the initial setting condition.

In order to enable the above-described second embodiment, the driving voltage supply circuit receives the touch enable signal TS, the touch control signal TC from the read-out integrated circuit 80, and the charge detection signal Q. A level shifter 62 is provided to selectively determine the potential VL or the high potential VH.

FIG. 13 is a timing diagram of FIG. 12.

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

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

Subsequently, when a non-contact state is detected from the readout integrated circuit, the touch control TC is output so that the touch enable signal TS is switched to a low level, and at the low level of the touch enable signal TS. Drive voltage also switches to low potential (VL)

Subsequently, after the low potential VL driving, when the charge amount change signal Q is applied by detecting a contact state through a touch sensing means such as the transparent conductive film, the touch enable signal is switched to a high level. As a result, the driving voltage is switched to the high potential VH.

On the other hand, while the above-described low potential (VL) driving is detected whether the contact is provided with a separate transparent conductive film, in some cases, the intermediate level of the high potential (VH) and low potential (VL) in the touch disabled state In this case, it is possible to consider a case in which a contact voltage can be detected by applying a low driving voltage to directly output a voltage change from the readout integrated circuit 80.

In the second embodiment described above, after the input from the external button, the above-described steps 105S to 130S in Fig. 10 occur repeatedly to apply the driving voltage Vdrv.

In the driving method according to the second embodiment of the present invention, the user can first select and designate whether the touch is sensed through the external button. In addition, the touch sensor unit is driven by applying a high potential driving voltage again by detecting a predetermined amount of charge. That is, the charge amount sensing means may be set in the external button and the driving voltage supply circuit to switch the value of the driving voltage, thereby preventing deterioration of the touch sensor unit due to continuous high potential application.

In addition, the liquid crystal display of the present invention for achieving the same object is not provided with a separate contact sensing means such as the transparent conductive film described above, it may be made by different voltage application method in the driving voltage supply circuit.

That is, in the touch sensing step performed after the external button is applied, after the output of the lead-out integrated circuit has not been output for a predetermined time, the driving voltage value is higher than the low potential level value before the external button is applied and is smaller than the high potential level. In order to apply whether the touch is detected as possible. In this case, the value set as the driving voltage has three levels of low potential, high potential and intermediate potential.

In addition, the driving method of the liquid crystal display according to this is as follows.

First, according to a user's decision, a touch-sensitive enable signal is supplied to the driving voltage supply circuit from a low level to a high level.

Subsequently, a high potential driving voltage is applied from the driving voltage supply circuit to the touch sensor unit in synchronization with the enable signal.

Then, it is determined whether there is no output from the readout integrated circuit for a first time or more.

Subsequently, when the output from the readout integrated circuit has not passed the first time, the touch enable signal is switched to the mid level, and the deterioration between the high potential and the low potential is prevented from the driving voltage supply circuit to the touch sensor unit. Apply voltage.

After touch sensing, the touch enable signal is switched to a high level by a change in an output value from the readout integrated circuit, and a high potential driving voltage is applied from the touch driving voltage supply circuit to the touch sensor unit.

On the other hand, in the above-described embodiments, during the touch driving, as in the initial condition, the driving voltage of the high potential voltage is applied to each of the driving voltage lines to detect the touch sensor unit at a predetermined position according to the contact, and thereby The touch position is detected by the application to implement display and specific functions.

In addition, in the above description, the voltage applied to the touch sensor unit is a high potential (8-20V) and a low potential (reference voltage level, about 0-2V) as an example, but in some cases, the current flowing in the touch sensor unit The reverse direction may be achieved by applying a reference voltage level Vref (about 0 to 2V) and a low potential voltage lower than the reference voltage level. That is, the operation condition of the touch sensor unit may be a specific voltage of a threshold voltage applied to the gate electrode of the sensing capacitor, and a voltage difference may be applied between the source electrode and the drain electrode, and the non-operation condition of the touch sensor unit may be a gate of the sensing transistor. The voltages of the electrodes, the drain electrodes, and the source electrodes may be matched with the reference voltage Vref.

On the other hand, the present invention described above is not limited to the above-described embodiment and the accompanying drawings, it is possible that various substitutions, modifications and changes within the scope without departing from the technical spirit of the present invention. It will be apparent to those of ordinary skill in Esau.

1 is an equivalent circuit diagram of an active matrix 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 of the present invention.

4 is a circuit diagram illustrating in detail each pixel of FIG. 3.

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

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

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

8 is a detailed configuration diagram illustrating a circuit of a driving voltage supply circuit.

9 is a timing diagram of a touch sensing signal and a driving voltage signal of FIG. 7.

10 is a flowchart illustrating a method of driving a liquid crystal display according to a second exemplary embodiment of the present invention.

11 is a schematic diagram showing a means for detecting whether a contact is made after deterioration driving according to lead-out detection after touch enable

12 is a detailed block diagram illustrating the driving voltage supply circuit of FIG. 10.

13 is a timing diagram of FIG. 12.

Explanation of symbols on the main parts of the drawings

10 liquid crystal panel 20 data driving circuit

30: gate driving circuit 40: timing controller

50: touch sensing controller 60: driving voltage supply circuit

62: level shifter 95: counter

70 backlight unit 80 readout 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: touch sensor built-in liquid crystal display device

Claims (11)

A liquid crystal panel including a plurality of gate lines and data lines crossing each other to define a pixel area, a pixel transistor in the pixel areas, a read out line connected to a touch sensor unit and an output terminal of the touch sensor unit; A driving circuit for supplying driving signals to the gate lines and the data lines, respectively; A timing controller for controlling driving timing of the driving circuit; A backlight unit for irradiating light onto the rear surface of the liquid crystal panel; And A lead-out integrated circuit to which the lead-out line of the touch sensor unit is commonly connected; A touch sensing controller configured to generate a touch enable signal for switching to a touch sensing state according to a user's instruction and an output of the readout integrated circuit; And And a driving voltage supply circuit for supplying a voltage level different from a high potential voltage required for driving the touch sensor unit in the pixel region and a low potential voltage according to the touch enable signal. The method of claim 1, And the user's instruction is made by an external button formed outside the liquid crystal panel. The method of claim 1, The switching from the high potential voltage to the low potential voltage of the driving voltage supply circuit is performed when the output value from the readout integrated circuit does not change for a predetermined time. The method of claim 1, And the driving voltage supply circuit further includes a counter for counting a time period during which the low potential voltage is maintained. The method of claim 1, And a transparent conductive film having a charge amount changed in response to touch detection on a front surface of the liquid crystal panel to correspond to the contact surface of the liquid crystal panel. A liquid crystal panel having a plurality of pixel regions, including pixel transistors in each pixel region, and having a touch sensor capable of detecting light in some pixel regions; and generating a driving voltage signal to control whether the touch sensor is driven or not; A driving voltage supply circuit comprising: a readout integrated circuit connected to the touch sensor and outputting and amplifying a photocurrent of a touch part to detect the driving current. At the user's discretion, supplying a touch-sensitive enable signal from a low level to a high level to the driving voltage supply circuit; Applying a high potential driving voltage from the driving voltage supply circuit to a touch sensor unit in synchronization with the enable signal; Determining whether there is no output from the readout integrated circuit for more than a first time; Switching the touch enable signal to a low level when the output from the readout integrated circuit has not elapsed a first time and applying a low potential drive voltage from the drive voltage supply circuit to the touch sensor unit; And Counting a second time after the low level switching, supplying the touch enable signal to a high level after a second time elapses, and applying a high potential driving voltage from the touch driving voltage supply circuit to the touch sensor unit; A driving method of a liquid crystal display device, comprising the. A liquid crystal panel having a plurality of pixel regions, including pixel transistors in each pixel region, and having a touch sensor capable of detecting light in some pixel regions; and generating a driving voltage signal to control whether the touch sensor is driven or not; A driving voltage supply circuit connected to the touch sensor, the readout integrated circuit configured to output and amplify the photocurrent of the touch region; In the driving method of a liquid crystal display device comprising a touch sensing means, Supplying a touch-sensitive enable signal from a low level to a high level according to a user's judgment; Applying a high potential driving voltage from the driving voltage supply circuit to a touch sensor unit in synchronization with the enable signal; Determining whether an output from the read out integrated circuit has not changed for more than a first time; Switching the touch enable signal to a low level when the output from the readout integrated circuit has not elapsed a first time and applying a low potential drive voltage from the drive voltage supply circuit to the touch sensor unit; And converting the touch enable signal to a high level through the touch sensing means and applying a high potential driving voltage from the touch driving voltage supply circuit to the touch sensor unit. Driving method of liquid crystal display device. The method according to claim 6 or 7, The determination of the user is provided with an external button on the liquid crystal panel and is driven by pressing the external button. The method of claim 6, And a counter for counting a second time in the driving voltage supply circuit. The method of claim 7, wherein And the touch sensing means is a transparent conductive film attached to the contact surface side of the liquid crystal panel. The method according to claim 6 or 7, Determining whether an output from the readout integrated circuit has not changed for more than a first time; If the output from the readout integrated circuit is within a first time, the touch enable signal is maintained at a high level, and a high potential drive voltage is applied from the drive voltage supply circuit to the touch sensor section. Method of driving the device.

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