TWI414987B - Liquid crystal display having touch sensing functionality and touch sensing method thereof - Google Patents

Abstract

A liquid crystal display having touch sensing functionality includes a display panel having plural pixel units and a touch sensing mechanism integrated in the display panel. The touch sensing mechanism includes a first sense gate line for delivering a first sense gate signal, a second sense gate line for delivering a second sense gate signal, a bias line for delivering a bias signal, a sensing unit, a readout line, and a signal processing circuit. The sensing unit is utilized for providing a readout signal according to the first sense gate signal, the second sense gate signal and the bias signal. The readout line delivers the readout signal to the signal processing circuit. And the signal processing circuit is utilized for locating a touched position according to the readout signal.

Description

Liquid crystal display device with touch sensing function and touch sensing method thereof

The invention relates to a liquid crystal display device, in particular to a liquid crystal display device with a touch sensing function and a touch sensing method thereof.

Liquid crystal display (LCD) has the advantages of slimness, power saving and low radiation, so it has been widely used in multimedia players, mobile phones, personal digital assistants (PDAs), computer monitors, or flat-panel TVs. And other electronic products. In addition, the function of performing touch input using a liquid crystal display device has become popular, that is, the application of the touch type liquid crystal display device has become more and more widespread. Generally, the touch panel of the touch type liquid crystal display device mainly includes a resistive touch panel and a capacitive touch panel. The resistive touch panel is positioned with a voltage drop to locate the touch, but does not provide multi-touch sensing. Capacitive touch panels typically include a sensing capacitor that signals the change in capacitance of the sensing capacitor corresponding to the touch point to locate the touch location.

FIG. 1 is a schematic structural view of a conventional touch panel device. As shown in FIG. 1, the touch panel device 100 includes a touch panel 101, a plurality of readout lines 110, a plurality of sense capacitors 120, a plurality of storage capacitors 140, and a plurality of comparators 150. When the touch panel 101 is touched, the capacitance value of the sensing capacitor 120 corresponding to the touch position changes, causing the capacitance voltage to change accordingly. The change of the capacitor voltage is transmitted to the corresponding storage capacitor 140 via the corresponding readout line 110. Then, the comparison comparator 150 performs a comparison process between the capacitance voltage of the storage capacitor 140 and the reference voltage Vref to generate the touch read signal Sro. However, as the size of the touch panel 101 increases, the line resistance of the sense line 110 increases, so after the amount of change in the capacitance voltage of the sense capacitor 120 is transferred to the storage capacitor 140, the voltage drop due to the line resistance Significantly reduced, resulting in low touch sensitivity. In addition, since the parasitic capacitance of the sense line 110 is also increased, the transmission delay of the capacitor voltage is more severe, thereby reducing the touch reaction speed. In addition, for a display device that is thin and low in appearance, the touch panel 101 attached to the display panel cannot meet the requirements.

According to an embodiment of the invention, a liquid crystal display device with a touch sensing function is disclosed, which comprises a pixel gate line for transmitting a pixel gate signal and a pixel data line for transmitting a pixel data signal. a pixel unit electrically connected to the pixel gate line and the pixel data line, a first sensing gate line for transmitting the first sensing gate signal, and a second sensing signal for transmitting the second sensing gate signal The second sensing gate line, the bias line for transmitting the bias signal, the sensing unit, the readout line, and the signal processing circuit. The pixel unit is used to output an image signal based on the pixel gate signal and the pixel data signal. The sensing unit is electrically connected to the first sensing gate line, the second sensing gate line and the bias line for providing according to the first sensing gate signal, the second sensing gate signal and the bias signal Read the signal. The sense line is electrically connected to the sensing unit for transmitting the read signal. The signal processing circuit is electrically connected to the readout line for positioning the touch position based on the read signal.

The invention further discloses a touch sensing method for a liquid crystal display device with a touch sensing function to position a touch position. The liquid crystal display device includes a first sensing gate line for transmitting a first sensing gate signal, a second sensing gate line for transmitting a second sensing gate signal, and a transmission bias signal. A bias line, a sensing unit, a readout line, and a signal processing circuit. The sensing unit is configured to provide an analog read signal according to the first sensing gate signal, the second sensing gate signal and the bias signal. The read line transmits an analog read signal to the signal processing circuit, and the signal processing circuit is used to read the signal according to the analog to locate the touch position.

The touch sensing method includes: providing a second sensing gate signal having a first pulse wave to a second sensing gate line in a first time period; providing a first pulse in the first time period The second pulse of the second pulse wave overlaps the bias line; in the first time period, the sensing unit performs charging according to the first pulse of the second sensing gate signal and the second pulse of the bias signal a second time period, the sensing unit performs a discharging process to generate a sensing voltage; and during a third time period, providing a first sensing gate signal having a third pulse wave to the first sensing gate line, The measuring unit supplies the analog read signal to the read line according to the sensing voltage and the third pulse of the first sensing gate signal; in the third time period, the signal processing circuit converts the analog read signal into a digital read The signal signal; and during the fourth time period, the signal processing circuit reads the signal according to the digit to locate the touch position.

The liquid crystal display device with the touch sensing function and the touch sensing method thereof are described in detail below with reference to the accompanying drawings, but the embodiments provided are not intended to limit the scope of the present invention. The method flow step number is not intended to limit its execution order. Any method that is recombined by method steps and produces equal effect is the scope covered by the present invention.

Fig. 2 is a view showing a liquid crystal display device with a touch sensing function according to a first embodiment of the present invention. As shown in FIG. 2, the liquid crystal display device 200 includes a plurality of pixel gate lines 201, a plurality of pixel data lines 202, a plurality of pixel units 205, a plurality of sensing gate lines 210, and a plurality of bias lines 215. And a plurality of readout lines 220, a plurality of sensing units 230, and a signal processing circuit 250. Each pixel gate line 201 is used to transmit a corresponding pixel gate signal. Each pixel data line 202 is used to transmit a corresponding pixel data signal. Each pixel unit 205 includes a pixel transistor Qpx, a liquid crystal capacitor Clc, and a first storage capacitor Cst1. The pixel transistor Qpx can be a thin film transistor or a field effect transistor. The pixel transistor Qpx is electrically connected to the corresponding pixel gate line 201 and the corresponding pixel data line 202 for controlling the writing operation of the corresponding pixel data signal according to the corresponding pixel gate signal, and the pixel unit 205 is The corresponding image signal is output according to the corresponding pixel data signal written. Each of the readout lines 220 is electrically coupled to the plurality of corresponding sense units 230 for transmitting corresponding analog read signals.

The signal processing circuit 250 includes a plurality of switches 255, a plurality of comparators 260, a multiplexer 270, a memory unit 280, and a signal locating unit 290. Each switch 255 is electrically coupled to the corresponding sense line 220 for resetting the voltage of the corresponding analog read signal to a low supply voltage Vss. Each comparator 260 includes a positive input terminal, a negative input terminal and an output terminal, wherein the positive input terminal is used to receive the reference voltage Vref, and the negative input terminal is electrically connected to the corresponding readout line 220 to receive the corresponding analog read signal, and the output terminal is electrically The multiplexer 270 is connected to output a corresponding digital read signal generated by comparing the analog read signal with the reference voltage Vref. For example, the comparator CP_j is electrically connected to the read line RLj for comparing the analog read signal Sroa_j with the reference voltage Vref to generate the digital read signal Srod_j, and the comparator CP_m is electrically connected to the read line RLm. The analog read signal Sroa_m is compared with the reference voltage Vref to generate a digital read signal Srod_m. In another embodiment, the positive input of comparator 260 is electrically coupled to corresponding sense line 220 for receiving a corresponding analog read signal, and the negative input of comparator 260 is for receiving a reference voltage Vref. The multiplexer 270 is electrically coupled to the complex comparator 260 for sequentially outputting the complex digital read signals generated by the complex comparator 260 to the memory unit 280. The memory unit 280 is electrically connected to the multiplexer 270 for storing the plurality of bit read signals sequentially output by the multiplexer 270. The signal locating unit 290 is electrically connected to the memory unit 280 for reading the signal according to the plurality of digits to generate the touch position signal Spos.

In the embodiment shown in FIG. 2, each pixel unit 205 is adjacent to the sensing unit 230. In another embodiment, the sensing unit 230 can be disposed by spacing the plurality of pixel gate lines 201, or by spacing the plurality of pixel data lines 202, that is, not every pixel unit 205 and the sensing unit 230. Adjacent. Similarly, the sense gate line 210 and the bias line 215 may be disposed corresponding to the plurality of pixel gate lines 201, or the read line 220 may be correspondingly spaced apart by the plurality of pixel data lines 202. Each sensing unit 230 includes a first transistor 231, a second transistor 232, a third transistor 233, a second storage capacitor Cst2, and a touch sensor 240. The first transistor 231 and the second transistor 232 may be an N-type Thin Film Transistor or an N-type Field Effect Transistor. The third transistor 233 may be an N-type thin film photo-transistor or an N-type field effect photonic crystal. The sensing unit DXn_m is hereinafter described to explain the coupling relationship of each component and the circuit operation principle.

The first transistor 231 includes a first end, a second end and a gate terminal, wherein the first end is for receiving the high power supply voltage Vdd, the gate terminal is electrically connected to the second storage capacitor Cst2, and the second end is electrically connected to the second transistor. 232. The second transistor 232 includes a first end, a second end and a gate terminal, wherein the first end is electrically connected to the second end of the first transistor 231, and the gate terminal is electrically connected to the sensing gate line DGLn-1 to receive the sense The gate signal SDGn-1 is measured, and the second terminal is electrically connected to the readout line RLm. The second storage capacitor Cst2 is electrically connected between the gate terminal of the first transistor 231 and the sensing gate line DGLn. The third transistor 233 includes a first end, a second end and a gate terminal, wherein the first end is electrically connected to the gate terminal of the first transistor 231, and the gate terminal is electrically connected to the sensing gate line DGLn to receive the sensing gate The signal SDGn, the second end is electrically connected to the bias line BLn. The touch sensor 240 is electrically connected between the gate terminal of the first transistor 231 and the bias line BLn. The touch sensor 240 is based on a contact mechanism or an inductive mechanism to change the conductive state between the gate terminal of the first transistor 231 and the bias line BLn, thereby changing the magnitude of the touch current It to adjust the second storage capacitor. The discharge speed of Cst2 is accordingly generated to generate a corresponding sensing voltage Vd. As shown in FIG. 2, the sensing voltage Vd stored in the second storage capacitor Cst2 is used to control the on/off state of the first transistor 231, thereby controlling the high power supply voltage Vdd to be fed to the readout line RLm to set Analogously, the voltage of the signal Sroa_m is read, so the amount of change in the sense voltage Vd is not affected by the line resistance of the sense line RLm. In other words, the touch sensitivity is not lowered by the increase in the line resistance of the sense line RLm. In addition, since the sensing unit 230 is integrated in the display panel including the pixel unit 205, the liquid crystal display device 200 can be made thinner and thinner, and the production cost thereof can be reduced.

FIG. 3 is a schematic diagram showing the waveforms of the operation-related signals of the liquid crystal display device 200 of FIG. 2 without a touch event during the sensing period, wherein the horizontal axis is the time axis. In FIG. 3, the signals from top to bottom are the sense gate signal SDGn-1, the sense gate signal SDGn, the bias signal Vb_n, the sense voltage Vd corresponding to the low ambient light brightness, and the corresponding Sensing voltage Vd of high ambient light brightness. As shown in FIG. 3, during the period T1, the voltage of the sense gate signal SDGn is the first high voltage Vh1, thereby turning on the third transistor 233. At this time, the bias signal Vb_n has a second high voltage Vh2 greater than the first high voltage Vh1 to charge the second storage capacitor Cst2, and the sensing voltage Vd thus rises to the saturation voltage Vsat. During the period T2, the low voltage of the sense gate signal SDGn causes the third transistor 233 to be turned off, and the second storage capacitor Cst2 is discharged by the drain current of the third transistor 233, so the sense voltage Vd is saturated. The voltage Vsat gradually decreases. In addition, since the third transistor 233 is a photoelectric crystal, the higher the ambient light brightness, the larger the leakage current of the third transistor 233, and the faster the discharge speed of the second storage capacitor Cst2, that is, the sensing voltage Vd. The faster the rate of decline. Therefore, as shown in FIG. 3, the falling speed of the sensing voltage Vd corresponding to the brightness of the high ambient light is greater than the falling speed of the sensing voltage Vd corresponding to the low ambient light brightness, but regardless of the brightness of the ambient light, the sensing The voltage Vd continues to be greater than the threshold voltage Vth of the first transistor 231, in other words, the first transistor 231 is continuously maintained in an on state.

During the period T3, the voltage of the sense gate signal SDGn-1 is the first high voltage Vh1 to turn on the second transistor 232, and at the same time, since the sense voltage Vd is still greater than the threshold voltage Vth to turn on the first transistor 231, The high power supply voltage Vdd can be fed to the sense line RLm via the first transistor 231 and the second transistor 232, that is, the voltage of the analog read signal Sroa_m is pulled up to the high power supply voltage Vdd. At this time, the comparator CP_m compares the analog read signal Sroa_m having the high power supply voltage Vdd with the reference voltage Vref to generate the digital read signal Srod_m, and the digital read signal Srod_m is transmitted to the memory unit 280 via the multiplexer 270. When the digital read signal Srod_m is stored in the memory unit 280, the corresponding switch 255 can be turned on to reset the voltage of the analog read signal Sroa_m to the low power supply voltage Vss. After all the digital read signals are sequentially stored in the memory unit 280 in the sensing period, the signal positioning unit 290 can read the signals according to the plurality of bits stored in the memory unit 280 to generate the touch position signal Spos.

FIG. 4 is a schematic diagram showing the waveforms of the operation-related signals of the liquid crystal display device 200 of FIG. 2 in a sensing period, wherein the horizontal axis is the time axis. In FIG. 4, the signals from top to bottom are the sense gate signal SDGn-1, the sense gate signal SDGn, the bias signal Vb_n, the sense voltage Vd corresponding to the low ambient light brightness, and the corresponding Sensing voltage Vd of high ambient light brightness. As shown in FIG. 4, during the period T1, the voltage of the sense gate signal SDGn is the first high voltage Vh1, thereby turning on the third transistor 233. At this time, the bias signal Vb_n has a second high voltage Vh2 greater than the first high voltage Vh1 to charge the second storage capacitor Cst2, and the sensing voltage Vd thus rises to the saturation voltage Vsat. During the period T2 (pre-discharge period), the low voltage of the sense gate signal SDGn turns off the third transistor 233, and the second storage capacitor Cst2 can be discharged by the drain current of the third transistor 233. The measured voltage Vd gradually decreases from the saturation voltage Vsat. Similarly, if the ambient light brightness is higher, the leakage current of the third transistor 233 is larger, and the discharge speed of the second storage capacitor Cst2 is also faster, that is, the faster the detection voltage Vd is falling.

When a touch event occurs, the second storage capacitor Cst2 is mainly discharged by the touch current It, and it is assumed that the touch period includes the period T3, T4 or the period T3', T4', thus corresponding to the low ambient light brightness. The sensing voltage Vd rapidly drops during the periods T3 and T4, and the sensing voltage Vd corresponding to the high ambient light luminance rapidly drops during the periods T3' and T4'. The sensing voltage Vd is still greater than the threshold voltage Vth of the first transistor 231 in the period T3 / period T3', but the sensing voltage Vd is smaller than the threshold voltage Vth of the first transistor 231 in the period T4 / period T4', so The first transistor 231 is switched to an off state within the period T4 / period T4'. Please note that the amount of decrease of the sensing voltage Vd in the period T2 (pre-discharge period) can cause the first transistor 231 to switch to the off state more quickly after the touch event occurs, thereby shortening the period T4/time period T4' The length of time to increase the speed of the touch reaction. In addition, the amount of decrease in the sensing voltage Vd corresponding to the high ambient light brightness in the period T2 is greater than the amount of decrease in the sensing voltage Vd corresponding to the low ambient light brightness in the period T2, so after the touch event occurs, the period The length of time T3' is shorter than the length of time period T3. In other words, the higher the ambient light brightness, the faster the first transistor 231 switches to the off state after the touch event occurs, so that the touch reaction speed can be adjusted according to the ambient light brightness.

During the period T5, the voltage of the sense gate signal SDGn-1 is the first high voltage Vh1 to turn on the second transistor 232, but since the sense voltage Vd is less than the threshold voltage Vth to turn off the first transistor 231, The high power supply voltage Vdd cannot be fed to the sense line RLm via the first transistor 231 and the second transistor 232, that is, the analog read signal Sroa_m is kept at a low voltage. At this time, the comparator CP_m compares the analog read signal Sroa_m having a low voltage with the reference voltage Vref to generate a digital read signal Srod_m, and the digital read signal Srod_m is transmitted to the memory unit 280 via the multiplexer 270. When the digital read signal Srod_m is stored in the memory unit 280, the corresponding switch 255 can be turned on to reset the voltage of the analog read signal Sroa_m to the low power supply voltage Vss. Similarly, when all the digital read signals are sequentially stored in the memory unit 280 during the sensing period, the signal positioning unit 290 can read the signals according to the plurality of bits stored in the memory unit 280 to generate the touch position signal Spos.

Fig. 5 is a view showing a liquid crystal display device with a touch sensing function according to a second embodiment of the present invention. As shown in FIG. 5, the liquid crystal display device 300 is similar to the liquid crystal display device 200 shown in FIG. 2, and the main difference is that the signal processing circuit 250 is replaced with the signal processing circuit 350. The signal processing circuit 350 includes a plurality of switches 355, a multiplexer 370, a comparator 360, a memory unit 380, and a signal locating unit 390. Each switch 355 is electrically coupled to the corresponding sense line 220 for resetting the voltage of the corresponding analog read signal to a low supply voltage Vss. The multiplexer 370 is electrically coupled to the complex sense line 220 for sequentially outputting the complex analog read signals to the comparator 360. Note that the multiplexer 270 shown in FIG. 2 is a digital multiplexer, and the multiplexer 370 is an analog multiplexer. The comparator 360 includes a positive input terminal, a negative input terminal and an output terminal, wherein the positive input terminal is used to receive the reference voltage Vref, and the negative input terminal is electrically connected to the multiplexer 370 to sequentially receive the analog read signal, and the output terminal is electrically connected to the output terminal. The memory unit 380 is configured to output a digital read signal generated by comparing the analog read signal with the reference voltage Vref. In another embodiment, the positive input of the comparator 360 is electrically coupled to the multiplexer 370 for sequentially receiving the analog read signal, and the negative input of the comparator 360 is for receiving the reference voltage Vref. The memory unit 380 is electrically connected to the comparator 360 for storing the digital read signals sequentially generated by the comparator 360. The signal locating unit 390 is electrically connected to the memory unit 380 for reading the signal according to the plurality of bits to generate the touch position signal Spos. The signal waveforms of the sense gate signal SDGn-1, the sense gate signal SDGn, the bias signal Vb_n, and the sense voltage Vd during operation of the liquid crystal display device 300 are substantially the same as those shown in FIGS. 3 and 4. Waveforms, so we won't go into details about how it works.

Fig. 6 is a view showing a liquid crystal display device with a touch sensing function according to a third embodiment of the present invention. As shown in FIG. 6, the liquid crystal display device 400 is similar to the liquid crystal display device 200 shown in FIG. 2, and the main difference is that the complex sensing unit 230 is replaced with the complex sensing unit 430, and the signal processing circuit 250 is replaced with Signal processing circuit 450. The internal structure of the sensing unit 430 is similar to the sensing unit 230 shown in FIG. 2, and the main difference is that the first transistor 231, the second transistor 232, and the third transistor 233 are replaced with the first transistor 431, respectively. The second transistor 432 and the third transistor 433. The first transistor 431 and the second transistor 432 may be a P-type thin film transistor or a P-type field effect transistor. The third transistor 433 may be a P-type thin film photovoltaic crystal or a P-type field effect photoelectric crystal. The coupling of the internal components of the sensing unit 430 is the same as that of the sensing unit 230 except that the first end of the first transistor 431 is used to receive the low power supply voltage Vss.

The internal structure of the signal processing circuit 450 is similar to the signal processing circuit 250 shown in FIG. 2, with the main difference being that the complex switch 255 is replaced with a complex switch 455, and the complex comparator 260 is replaced with a complex comparator 460. Each switch 455 is electrically coupled to the corresponding sense line 220 for resetting the voltage of the corresponding analog read signal to a high power supply voltage Vdd. Each comparator 460 includes a positive input terminal, a negative input terminal and an output terminal, wherein the negative input terminal is used to receive the reference voltage Vref, and the positive input terminal is electrically connected to the corresponding readout line 220 to receive the corresponding analog read signal, and the output terminal is electrically The multiplexer 270 is connected to output a corresponding digital read signal generated by comparing the analog read signal with the reference voltage Vref. In another embodiment, the positive input of comparator 460 is used to receive reference voltage Vref, and the negative input of comparator 460 is electrically coupled to corresponding sense line 220 to receive a corresponding analog read signal. The remaining coupling relationship of the signal processing circuit 450 is the same as the signal processing circuit 250. The signal waveforms of the sense gate signal SDGn-1, the sense gate signal SDGn, the bias signal Vb_n, and the sense voltage Vd during operation of the liquid crystal display device 400 are substantially corresponding to the waveforms of FIGS. 3 and 4. The waveform is inverted up and down, for example, the waveform of the sense gate signal SDGn and the bias signal Vb_n in the period T1 is a negative pulse, instead of the positive pulse shown in FIGS. 3 and 4. In addition, the charging operation of the second storage voltage Cst2 in the period T1 is for lowering the sensing voltage Vd to the saturation voltage Vsat, and the discharging operation during the period T2 is for gradually decreasing the sensing voltage Vd from the saturation voltage Vsat. rise.

Fig. 7 is a view showing a liquid crystal display device with a touch sensing function according to a fourth embodiment of the present invention. As shown in FIG. 7, the liquid crystal display device 500 is similar to the liquid crystal display device 400 shown in FIG. 6, and the main difference is that the signal processing circuit 450 is replaced with the signal processing circuit 450. The signal processing circuit 550 includes a plurality of switches 555, a multiplexer 570, a comparator 560, a memory unit 580, and a signal locating unit 590. Each switch 555 is electrically coupled to the corresponding sense line 220 for resetting the voltage of the corresponding analog read signal to a high power supply voltage Vdd. The multiplexer 570 is electrically coupled to the complex sense line 220 for sequentially outputting the complex analog read signals to the comparator 560. Note that the multiplexer 270 shown in FIG. 6 is a digital multiplexer, and the multiplexer 570 is an analog multiplexer. The comparator 560 includes a positive input terminal, a negative input terminal and an output terminal, wherein the negative input terminal is used to receive the reference voltage Vref, and the positive input terminal is electrically connected to the multiplexer 570 to sequentially receive the analog read signal, and the output terminal is electrically connected to the output terminal. The memory unit 580 is configured to output a digital read signal generated by comparing the analog read signal with the reference voltage Vref. In another embodiment, the positive input of comparator 560 is used to receive reference voltage Vref, and the negative input of comparator 560 is electrically coupled to multiplexer 570 to sequentially receive analog read signals. The memory unit 580 is electrically connected to the comparator 560 for storing the digital read signals sequentially generated by the comparator 560. The signal locating unit 590 is electrically connected to the memory unit 580 for reading the signal according to the plurality of bits to generate the touch position signal Spos. Except for the internal structure and circuit operation of the above-mentioned signal processing circuit 550, the rest of the structure and circuit operation of the liquid crystal display device 500 are the same as those of the liquid crystal display device 400, and will not be described again.

Figure 8 is a flow chart of the touch sensing method of the present invention. The flow 900 shown in Fig. 8 is a touch of the liquid crystal display device 200 according to Fig. 2, the liquid crystal display device 300 of Fig. 5, the liquid crystal display device 400 of Fig. 6, or the liquid crystal display device 500 of Fig. 7. Sensing method. The touch sensing method shown in the process 900 includes the following steps: Step S910: providing a sensing gate signal SDGn having a first pulse wave to a sensing gate line DGLn in a first period; step S920: first During a period of time, a bias signal Vb_n having a second pulse wave overlapping the first pulse wave is provided to the bias line BLn; and step S930: in the first time period, the sensing unit is configured according to the first pulse of the sensing gate signal SDGn Wave and the second pulse of the bias signal Vb_n to perform the charging process; step S940: in the second time period, the sensing unit performs a discharging process to generate the sensing voltage Vd; and in step S950: providing the first time in the third time period The three-pulse sensing gate signal SDGn-1 to the sensing gate line DGLn-1, the sensing unit provides an analog read signal according to the sensing voltage Vd and the third pulse of the sensing gate signal SDGn-1 Sroa_m is fed to the readout line RLm; step S960: in the third time period, the signal processing circuit converts the analog read signal Sroa_m into a digital read signal Srod_m; step S970: in the fourth time period, the signal processing circuit reads according to the digital The signal Srod_m generates a touch position signal Spos; and step S980 In the fourth period, the analog signal processing circuit Sroa_m the voltage sense signal is reset to the low supply voltage Vss or the high power supply voltage Vdd.

In the flow 900 of the touch sensing method described above, the discharge sequence is controlled by ambient light levels and/or touch events. In an embodiment, when the liquid crystal display device does not have a touch event during the second time period, the sensing unit outputs the high power supply voltage Vdd greater than the reference voltage Vref as the analog read signal Sroa_m in the third time period. When the liquid crystal display device generates a touch event in the second time period, the voltage of the analog read signal Sroa_m provided by the sensing unit in the third time period is less than the reference voltage Vref. In another embodiment, when the liquid crystal display device does not have a touch event during the second time period, the sensing unit outputs the low power supply voltage Vss smaller than the reference voltage Vref as the analog read signal Sroa_m in the third time period, When the liquid crystal display device generates a touch event in the second time period, the voltage of the analog read signal Sroa_m provided by the sensing unit in the third time period is greater than the reference voltage Vref.

In summary, in the operation of the sensing unit of the liquid crystal display device of the present invention, the sensing voltage is used to control the on/off state of the first transistor of the sensing unit, thereby controlling the high power supply voltage or the low power supply voltage. Feeded to the sense line to set the voltage of the analog read signal, so the amount of change in the sense voltage is not affected by the line resistance of the sense line, that is, the touch sensitivity is not increased by the line resistance of the sense line. reduce. In addition, the sensing voltage can be closer to the threshold voltage by the discharge program before the touch event occurs, so the touch reaction speed can be improved. In addition, the sensing unit of the liquid crystal display device of the present invention is integrated in the display panel including the pixel unit, so that the appearance thereof can be made thinner and thinner, and the production cost can be reduced.

While the present invention has been described above by way of example, it is not intended to limit the invention, and the invention may be modified and modified without departing from the spirit and scope of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims.

100. . . Touch panel device

101. . . Touch panel

110, 220. . . Readout line

120. . . Inductive capacitor

140. . . Storage capacitor

150, 260, 360, 460, 560. . . Comparators

200. . . Liquid crystal display device

201. . . Pseudo gate line

202. . . Pixel data line

205. . . Pixel unit

210. . . Sense gate line

215. . . Bias line

230,430. . . Sensing unit

231, 431. . . First transistor

232, 432. . . Second transistor

233, 433. . . Third transistor

240. . . Touch sensor

250, 350, 450, 550. . . Signal processing circuit

255, 355, 455, 555. . . switch

270, 370, 570. . . Multiplexer

280, 380, 580. . . Memory unit

290, 390, 590. . . Signal positioning unit

900. . . Process

BLn-1, BLn, BLn+1. . . Bias line

CP_j, CP_m. . . Comparators

Clc. . . Liquid crystal capacitor

Cst1. . . First storage capacitor

Cst2. . . Second storage capacitor

DGLn-1, DGLn, DGLn+1. . . Sense gate line

DXn_m, DXn+1_m. . . Sensing unit

It. . . Touch current

Qpx. . . Pixel crystal

RLj, RLm. . . Readout line

S910~S980. . . step

SDGn-1, SDGn, SDGn+1. . . Sense gate signal

Spos. . . Touch position signal

Sro. . . Touch the read signal

Sroa_j, Sroa_m. . . Analog reading signal

Srod_j, Srod_m. . . Digital read signal

T1, T2, T3, T4, T3', T4', T5. . . Time slot

Vb_n-1, Vb_n, Vb_n+1. . . Bias signal

Vd. . . Sense voltage

Vdd. . . High supply voltage

Vh1. . . First high voltage

Vh2. . . Second high voltage

Vref. . . Reference voltage

Vsat. . . Saturation voltage

Vss. . . Low supply voltage

Vth. . . Threshold voltage

FIG. 1 is a schematic structural view of a conventional touch panel device.

Fig. 2 is a view showing a liquid crystal display device with a touch sensing function according to a first embodiment of the present invention.

Fig. 3 is a schematic diagram showing the waveforms of the operation-related signals of the liquid crystal display device of Fig. 2 without a touch event during the sensing period, wherein the horizontal axis is the time axis.

Fig. 4 is a schematic diagram showing the waveforms of the operation-related signals of the liquid crystal display device of Fig. 2 in the sensing period, wherein the horizontal axis is the time axis.

Fig. 5 is a view showing a liquid crystal display device with a touch sensing function according to a second embodiment of the present invention.

Fig. 6 is a view showing a liquid crystal display device with a touch sensing function according to a third embodiment of the present invention.

Fig. 7 is a view showing a liquid crystal display device with a touch sensing function according to a fourth embodiment of the present invention.

Figure 8 is a flow chart of the touch sensing method of the present invention.

200. . . Liquid crystal display device

201. . . Pseudo gate line

202. . . Pixel data line

205. . . Pixel unit

210. . . Sense gate line

215. . . Bias line

220. . . Readout line

230. . . Sensing unit

231. . . First transistor

232. . . Second transistor

233. . . Third transistor

240. . . Touch sensor

250. . . Signal processing circuit

255. . . switch

260. . . Comparators

270. . . Multiplexer

280. . . Memory unit

290. . . Signal positioning unit

BLn-1, BLn, BLn+1. . . Bias line

CP_j, CP_m. . . Comparators

Clc. . . Liquid crystal capacitor

Cst1. . . First storage capacitor

Cst2. . . Second storage capacitor

DGLn-1, DGLn, DGLn+1. . . Sense gate line

DXn_m, DXn+1_m. . . Sensing unit

It. . . Touch current

Qpx. . . Pixel crystal

RLj, RLm. . . Readout line

SDGn-1, SDGn, SDGn+1. . . Sense gate signal

Spos. . . Touch position signal

Sroa_j, Sroa_m. . . Analog reading signal

Srod_j, Srod_m. . . Digital read signal

Vb_n-1, Vb_n, Vb_n+1. . . Bias signal

Vd. . . Sense voltage

Vdd. . . High supply voltage

Vref. . . Reference voltage

Vss. . . Low supply voltage

Claims (19)

A liquid crystal display device with a touch sensing function, comprising: a pixel gate line for transmitting a pixel gate signal; a pixel data line for transmitting a pixel data signal; a pixel The unit is electrically connected to the pixel gate line and the pixel data line for outputting an image signal according to the pixel gate signal and the pixel data signal; a first sensing gate line is used Transmitting a first sensing gate signal; a second sensing gate line for transmitting a second sensing gate signal; a bias line for transmitting a bias signal; a sensing unit, The first sensing gate line, the second sensing gate line and the bias line are connected to the first sensing gate signal, the second sensing gate signal and the bias signal Providing a first analog read signal; and a first read line electrically connected to the sensing unit for transmitting the first analog read signal; wherein the sensing unit comprises: a first transistor, The first end, the second end and the gate end are included, wherein the first end is used to receive a power voltage; The transistor includes a first end, a second end and a gate terminal, wherein the first end is electrically connected to the second end of the first transistor, and the gate terminal is electrically connected to the first sensing gate line Receiving the first sensing gate signal, the second end is electrically connected to the first sensing line; a storage capacitor is electrically connected to the gate terminal of the first transistor and the second sensing gate Between the pole lines; a third transistor comprising a first end, a second end and a gate terminal, wherein the first end is electrically connected to the gate terminal of the first transistor, and the gate terminal is electrically connected to the gate electrode a second sensing gate line for receiving the second sensing gate signal, the second end electrically connected to the bias line; and a touch sensor electrically connected to the gate terminal of the first transistor Between the bias lines. The liquid crystal display device of claim 1, further comprising: a second read line for transmitting a second analog read signal; a first switch electrically connected to the first read line for The voltage of the first analog read signal is reset to a power supply voltage; a second switch is electrically connected to the second read line for resetting the voltage of the second analog read signal to the power supply voltage; a first comparator electrically coupled to the first sense line for comparing the first analog read signal with a reference voltage to generate a first digital read signal; and a second comparator electrically coupled The second read line is configured to compare the second analog read signal with the reference voltage to generate a second digital read signal; wherein the power supply voltage is a low power supply voltage or a high power supply voltage. The liquid crystal display device of claim 2, further comprising: a multiplexer electrically connected to the first comparator and the second comparator for sequentially outputting the first digital read signal and the second Digital read signal; a memory unit electrically connected to the multiplexer for storing the first digital read signal and the second digital read signal sequentially output by the multiplexer; and a signal locating unit electrically connected to the memory And a unit configured to generate a touch position signal according to the first digital read signal and the second digital read signal. The liquid crystal display device of claim 1, further comprising: a second read line for transmitting a second analog read signal; a first switch electrically connected to the first read line for The voltage of the first analog read signal is reset to a power supply voltage; a second switch is electrically connected to the second read line for resetting the voltage of the second analog read signal to the power supply voltage; a multiplexer electrically connected to the first read line and the second read line for sequentially outputting the first analog read signal and the second analog read signal; and a comparator electrically connected The multiplexer is configured to compare the first analog read signal with a reference voltage to generate a first digital read signal, and to compare the second analog read signal with the reference voltage to generate a second The digital read signal; wherein the power supply voltage is a low power supply voltage or a high power supply voltage. The liquid crystal display device of claim 4, further comprising: a memory unit electrically connected to the comparator for storing the first digital read signal and the second digital read signal sequentially generated by the comparator And a signal locating unit electrically connected to the memory unit for using the first digit The read signal and the second digital read signal generate a touch position signal. The liquid crystal display device of claim 1, wherein: the first transistor and the second transistor system are N-type thin film transistors or N-type field effect transistors; and the third transistor system is an N-type film Photoelectric crystal or N-type field effect photoelectric crystal. The liquid crystal display device of claim 6, wherein the power supply voltage received by the first end of the first transistor is a high power supply voltage. The liquid crystal display device of claim 1, wherein: the first transistor and the second transistor system are a P-type film transistor or a P-type field effect transistor; and the third transistor system is a P-type film Photoelectric crystal or P-type field effect photoelectric crystal. The liquid crystal display device of claim 8, wherein the power supply voltage received by the first end of the first transistor is a low power supply voltage. The liquid crystal display device of claim 1, wherein the touch sensor is based on a contact mechanism or an inductive mechanism to change a conductive state between a gate terminal of the first transistor and the bias line. The liquid crystal display device of claim 1, wherein the pixel unit comprises: a transistor comprising a first end, a second end and a gate terminal, wherein the first end is electrically connected to the pixel data line to receive the pixel data signal, and the gate terminal is electrically connected to the pixel The gate line receives the pixel gate signal; a liquid crystal capacitor electrically connected to the second end of the transistor; and a storage capacitor electrically connected to the second end of the transistor. A touch sensing method, comprising: providing a liquid crystal display device with a touch sensing function, the liquid crystal display device comprising: a first sensing gate line for transmitting a first sensing gate signal; a second sensing gate line for transmitting a second sensing gate signal; a bias line for transmitting a bias signal; and a sensing unit for sensing the first sensing gate signal The second sensing gate signal and the bias signal provide an analog read signal; and a read line for transmitting the analog read signal; providing a first pulse during a first time period Transmitting the second sensing gate signal to the second sensing gate line; providing the bias signal having a second pulse wave overlapping the first pulse wave to the biasing period during the first time period The first detecting unit performs a charging process according to the first pulse wave of the second sensing gate signal and the second pulse wave of the bias signal; During the time period, the sensing unit performs a discharging process to generate a sensing voltage; and provides a device during a third time period The gate of the first sensing signal to the third pulse The first sensing gate line, the sensing unit is configured to supply the analog read signal to the readout line according to the sensing voltage and the third pulse of the first sensing gate signal. The touch sensing method of claim 12, wherein the discharging program is controlled by the brightness of ambient light. The touch sensing method of claim 12, wherein the discharging program is controlled by a touch event. The touch sensing method of claim 12, wherein the liquid crystal display device further comprises a signal processing circuit, the touch sensing method further comprising: during the third time period, the signal processing circuit reads the analogy The signal is converted into a digital read signal; in a fourth time period, the signal processing circuit generates a touch position signal according to the digital read signal; and during the fourth time period, the signal processing circuit reads the analogy The voltage of the signal is reset to a low supply voltage or a high supply voltage. The touch sensing method of claim 12, wherein if the liquid crystal display device does not generate a touch event during the second time period, the sensing unit will be greater than one of the reference voltages during the third time period. The high supply voltage output is the analog read signal. The touch sensing method of claim 16, wherein if the liquid crystal display device generates the touch event during the second time period, the sensing unit provides the analog read signal during the third time period. The voltage is less than the reference voltage. The touch sensing method of claim 12, wherein if the liquid crystal display device does not generate a touch event during the second time period, the sensing unit will be less than one of the reference voltages during the third time period. The low supply voltage output is the analog read signal. The touch sensing method of claim 18, wherein if the liquid crystal display device generates the touch event during the second time period, the sensing unit provides the analog read signal during the third time period. The voltage is greater than the reference voltage.