CN101900906B - Liquid crystal display device with touch sensing function and touch sensing method thereof - Google Patents

Abstract

A liquid crystal display device with touch sensing function comprises a display panel and a sensing unit integrated on the display panel. The display panel has scan lines for transmitting scan signals and readout lines for transmitting readout signals. The sensing unit resets the sensing voltage according to a low level voltage of the scan signal. The sensing unit also pulls up a sensing voltage according to a high level voltage of the scan signal, wherein an amount of increase of the sensing voltage is controlled by a touch event. The readout signal is generated by the sensing unit according to the sensing voltage and the high level voltage of the scan signal.

Description

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

technical field

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. the

Background technique

Liquid crystal display (Liquid Crystal Display, LCD) has the advantages of light and thin appearance, power saving and low radiation, so it has been widely used in multimedia players, mobile phones, personal digital assistants (PDA), computer monitors, or flat-screen TVs and other electronic products. In addition, the function of using the liquid crystal display device to perform touch input has gradually become popular, that is, the application of the touch-type liquid crystal display device is becoming more and more extensive. Generally speaking, the touch panels of touch-type liquid crystal display devices are mainly resistive touch panels and capacitive touch panels. The resistive touch panel locates the touch position by voltage drop, but cannot provide multi-touch sensing function. The capacitive touch panel generally includes a sensing capacitor, which processes the capacitance change of the sensing capacitor corresponding to the touch point for signal processing to locate the touch position. the

FIG. 1 is a schematic structural diagram of a known 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 sensing 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 touched position will change, causing its capacitor voltage to change accordingly, and the change in the capacitor voltage will be transmitted to the corresponding storage capacitor 140 through the corresponding readout line 110 , and then use the corresponding comparator 150 to perform a comparison process between the capacitor voltage of the storage capacitor 140 and the reference voltage Vref to generate the touch readout signal Sro. However, as the size of the touch panel 101 increases, the line resistance of the readout line 110 also increases, so after the change in the capacitance voltage of the sensing capacitor 120 is transmitted to the storage capacitor 140, the voltage drop due to the line resistance and significantly reduced, resulting in low touch sensitivity. In addition, since the parasitic capacitance of the readout line 110 also increases, the transmission delay of the capacitance voltage from the sensing capacitor 120 to the storage capacitor 140 will be more serious, thereby reducing the touch response speed. In addition, the touch panel 101 externally attached to the display panel cannot meet the requirements for a display device with a touch-sensing function that pursues thin and light appearance and low cost. the

Contents of the invention

An embodiment of the present invention discloses a liquid crystal display device with a touch sensing function, which includes scanning lines for transmitting scanning signals, sensing units, and readout lines. The sensing unit is electrically connected to the scan line and used for providing an analog readout signal according to the scan signal. The sensing unit includes a first transistor, a first capacitor, a second capacitor, and a second transistor. The first transistor includes a first terminal, a second terminal and a gate terminal, wherein the first terminal is electrically connected to the scan line, and the second terminal is electrically connected to the gate terminal. The first capacitor is electrically connected between the scan line and the second terminal of the first transistor. The second capacitor includes a first terminal and a second terminal, wherein the first terminal is electrically connected to the second terminal of the first transistor, and the second terminal is used for receiving the shared voltage. The second transistor includes a first terminal, a second terminal and a gate terminal, wherein the first terminal is electrically connected to the scan line, the gate terminal is electrically connected to the second terminal of the first transistor, and the second terminal is used for outputting an analog readout signal. The readout line is electrically connected to the second end of the second transistor for transmitting analog readout signals. During the operation of the sensing unit, the capacitance value of the second capacitor changes with the touch event, so as to generate an analog readout signal corresponding to the touch event. the

The present invention also discloses a touch sensing method, which includes: providing a liquid crystal display device with a touch sensing function, and the liquid crystal display device includes: scanning lines, used to transmit scanning signals; sensing units, electrically connected to the The scanning line is used to provide a first analog readout signal according to the scanning signal. The sensing unit includes: a first transistor including a first terminal, a second terminal and a gate terminal, wherein the first terminal is electrically connected to the scanning line, the second terminal is electrically connected to the gate terminal; the first capacitor is electrically connected between the scan line and the second terminal of the first transistor; the second capacitor includes a first terminal and a second terminal, wherein the The first terminal of the second capacitor is electrically connected to the second terminal of the first transistor, and the second terminal of the second capacitor is used to receive the shared voltage; and the second transistor includes a first terminal, a second terminal and a gate terminal, Wherein the first end of the second transistor is electrically connected to the scan line, the gate end of the second transistor is electrically connected to the second end of the first transistor, and the second end of the second transistor is used to output the first analog a readout signal; and a first readout line electrically connected to the second end of the second transistor for transmitting the first analog readout signal; wherein the capacitance value of the second capacitor changes with a touch event , so as to generate the first analog readout signal corresponding to the touch event; in the first period, provide the scan signal with a low level voltage to the scan line; in the first period, the sensing The unit resets a sensing voltage to the low level voltage according to the scanning signal; in the second period, the scanning signal with the high level voltage is provided to the scanning line; in the second period, the sensing The unit pulls up the sensing voltage according to the high level voltage of the scanning signal, wherein the increase of the sensing voltage is controlled by a touch event; and during the second period, the sensing unit pulls up the sensing voltage according to the sensing voltage and the scan signal with the high level voltage to provide the first analog readout signal fed to the first readout line. the

Description of drawings

FIG. 1 is a schematic structural diagram of a known touch panel device. the

FIG. 2 is a schematic diagram of a first embodiment of a liquid crystal display device with a touch sensing function according to the present invention. the

FIG. 3 is a schematic diagram of operation-related signal waveforms of the liquid crystal display device shown in FIG. 2 , where the horizontal axis is the time axis. the

FIG. 4 is a schematic diagram of a second embodiment of a liquid crystal display device with touch sensing function according to the present invention. the

FIG. 5 is a schematic diagram of a third embodiment of the liquid crystal display device with touch sensing function of the present invention. the

FIG. 6 is a schematic diagram of a fourth embodiment of a liquid crystal display device with a touch sensing function according to the present invention. the

FIG. 7 is a schematic diagram of a fifth embodiment of the liquid crystal display device with touch sensing function of the present invention. the

FIG. 8 is a schematic diagram of a sixth embodiment of the liquid crystal display device with touch sensing function of the present invention. the

FIG. 9 is a schematic diagram of a seventh embodiment of a liquid crystal display device with touch sensing function according to the present invention. the

FIG. 10 is a schematic diagram of an eighth embodiment of a liquid crystal display device with touch sensing function according to the present invention. the

FIG. 11 is a flow chart of the touch sensing method of the present invention. the

[Description of main component labels]

Detailed ways

The liquid crystal display device with touch-sensing function and its touch-sensing method according to the present invention will be described in detail below with specific embodiments in conjunction with the accompanying drawings, but the provided embodiments are not intended to limit the scope of the present invention. , and the step numbers of the method flow are not used to limit the order of their execution. Any method with the same effect produced by recombining the execution flow of the method steps is within the scope of the present invention. the

FIG. 2 is a schematic diagram of a first embodiment of a liquid crystal display device with a touch sensing function according to the present invention. As shown in FIG. 2 , the liquid crystal display device 200 includes a plurality of scanning lines 201, a plurality of data lines 202, a plurality of pixel units 205, a plurality of readout lines 220, a plurality of sensing units 230, and a signal processing circuit 250. Each scan line 201 is used to transmit a corresponding scan signal. Each data line 202 is used to transmit a corresponding data signal. Each pixel unit 205 includes a pixel transistor Qpx1 , a liquid crystal capacitor Clc1 and a storage capacitor Cst1 . The pixel transistor Qpx1 can be a thin film transistor or a field effect transistor. The pixel transistor Qpx1 includes a first terminal, a second terminal and a gate terminal, wherein the first terminal is electrically connected to the corresponding data line 202 to receive the corresponding data signal, the gate terminal is electrically connected to the corresponding scanning line 201 to receive the corresponding scanning signal, and the second terminal It is electrically connected to the liquid crystal capacitor Clc1 and the storage capacitor Cst1. The pixel transistor Qpx1 is used to control the writing operation of the corresponding data signal according to the corresponding scanning signal, and the pixel unit 205 outputs the corresponding image signal according to the written corresponding data signal. Each readout line 220 is electrically connected to a plurality of corresponding sensing units 230 for transmitting corresponding analog readout signals. the

The signal processing circuit 250 includes a plurality of switches 255 , a plurality of comparators 260 , a multiplexer 270 , a storage unit 280 , and a signal positioning unit 290 . Each switch 255 is electrically connected to the corresponding readout line 220 for resetting the voltage corresponding to the analog readout signal to the low power 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, the negative input terminal is electrically connected to the corresponding readout line 220 to receive the corresponding analog readout signal, and the output terminal is electrically connected to the corresponding analog readout signal. It is connected to the multiplexer 270 and is used for outputting a corresponding digital readout signal generated by comparing the corresponding analog readout signal with the reference voltage Vref. For example, the comparator CP_j is electrically connected to the readout line RLj for comparing the analog readout signal Sroa_j with the reference voltage Vref to generate a digital readout signal Srod_j, and the comparator CP_m is electrically connected to the readout line RLm for The analog readout signal Sroa_m is compared with the reference voltage Vref to generate a digital readout signal Srod_m. In another embodiment, the positive input terminal of the comparator 260 is electrically connected to the corresponding readout line 220 to receive the corresponding analog readout signal, and the negative input terminal of the comparator 260 is used to receive the reference voltage Vref. The multiplexer 270 is electrically connected to the plurality of comparators 260 for sequentially outputting the plurality of digital readout signals generated by the plurality of comparators 260 to the storage unit 280 . The storage unit 280 is electrically connected to the multiplexer 270 and is used for storing a plurality of digital readout signals sequentially output by the multiplexer 270 . The signal positioning unit 290 is electrically connected to the storage unit 280 and is used for generating a touch position signal Spos according to a plurality of digital readout signals. the

In the embodiment shown in FIG. 2 , each pixel unit 205 is adjacent to a sensing unit 230 . In another embodiment, the sensing units 230 may be arranged at intervals between a plurality of scan lines 201 or at intervals of a plurality of data lines 202 , that is, not every pixel unit 205 is adjacent to the sensing unit 230 . Similarly, the readout lines 220 can be correspondingly arranged at intervals between a plurality of data lines 202 . Each sensing unit 230 includes a first transistor 231, a first capacitor 232, a second capacitor 233, and a second transistor 234. The first transistor 231 and the second transistor 234 can be thin film transistors (Thin Film Transistor) or field effect transistors (Field Effect Transistor). The coupling relationship of each element and the operating principle of the circuit are described below according to the sensing unit DXn_m. the

The first transistor 231 includes a first terminal, a second terminal and a gate terminal, wherein the first terminal is electrically connected to the scan line SLn to receive the scan signal SSn, and the second terminal is electrically connected to the gate terminal. The first capacitor 232 includes a first terminal and a second terminal, wherein the first terminal is electrically connected to the scan line SLn, and the second terminal is electrically connected to the second terminal of the first transistor 231 . In a preferred embodiment, the second terminal of the first capacitor 232 is directly connected to the gate terminal of the first transistor 231, thereby reducing the layout area of the circuit. The second capacitor 233 includes a first terminal and a second terminal, wherein the first terminal is electrically connected to the second terminal of the first transistor 231 , and the second terminal is used to receive the shared voltage Vcom. The second transistor 234 includes a first terminal, a second terminal and a gate terminal, wherein the first terminal is electrically connected to the scan line SLn, the second terminal is electrically connected to the readout line RLm, and the gate terminal is electrically connected to the first terminal of the second capacitor 233. terminal to receive the sensing voltage VDn_m. When the scan signal SSn has a low-level voltage, the first transistor 231 is turned on, thereby resetting the sensing voltage VDn_m to a low-level voltage. When the scan signal SSn is switched from a low-level voltage to a high-level voltage, the first transistor 231 is switched to an off state so that the sensing voltage VDn_m becomes a floating voltage, and the sensing voltage can be pulled up through the coupling effect of the first capacitor 232 VDn_m, the pulled-up sensing voltage VDn_m can be represented by the following formula (1). the

$\mathrm{VD}\_m=\frac{\mathrm{<figure-callout\; id="1"\; label="C"\; filenames="HSA00000202348900021.png,HSA00000202348900031.png"\; state="\{\{state\}\}">C</figure-callout>}1\&times;\mathrm{Vgh}+C2\&times;\mathrm{<figure-callout\; id="1"\; label="vgl\; C"\; filenames="HSA00000202348900021.png,HSA00000202348900031.png"\; state="\{\{state\}\}">vgl</figure-callout>}}{C}$ ...Formula 1)

In formula (1), C1 is the capacitance of the first capacitor 232 , C2 is the capacitance of the second capacitor 233 , Vgh is the high-level voltage of the scan signal SSn, and Vgl is the low-level voltage of the scan signal SSn. The capacitance C2 of the second capacitor 233 is changed according to the touch event, so as to control the increase amount of the sensing voltage VDn_m being pulled up. In one embodiment, when a touch event occurs at the position of the panel corresponding to the sensing unit DXn_m, the capacitance C2 of the second capacitor 233 will increase, thereby reducing the amount of the sensing voltage VDn_m being pulled up. In the operation of the sensing unit DXn_m, the sensing voltage VDn_m is used to control the on/off state of the second transistor 234, and then control the high-level voltage of the scan signal SSn to be fed into the readout line RLm to set the analog readout. The voltage of the signal Sroa_m is output, so the function of the sensing voltage VDn_m will not reduce the performance due to the increase of the line resistance of the readout line RLm. In other words, the touch sensitivity of the sensing unit DXn_m will not be affected by the increase of the readout line RLm. decrease with an increase in wire resistance. In addition, since the sensing unit 230 is integrated into the display panel including the pixel unit 205 , the appearance of the liquid crystal display device 200 can be made thinner and the production cost thereof can be reduced. the

FIG. 3 is a schematic diagram of operation-related signal waveforms of the liquid crystal display device 200 shown in FIG. 2 , where the horizontal axis is the time axis. In FIG. 3 , the signals from top to bottom are the scan signal SSn-1, the scan signal SSn, the sensing voltage VDn-1_m, and the sensing voltage VDn_m. As shown in FIG. 3 , in the period T1, both the scan signal SSn-1 and the scan signal SSn have the low-level voltage Vgl, so the sensing voltage VDn-1_m and the sensing voltage VDn_m are both reset to the low-level voltage Vgl . In the period T2, the scan signal SSn-1 is switched from the low-level voltage Vgl to the high-level voltage Vgh, so the sensing unit DXn-1_m can pull up the sensing voltage VDn-1_m according to the coupling effect of its first capacitor 232 to the first high voltage Vh1. During the period T3, the scan signal SSn is switched from the low-level voltage Vgl to the high-level voltage Vgh, so the sensing unit DXn_m can pull up the sensing voltage VDn_m to the first high voltage Vh1 according to the coupling effect of the first capacitor 232 . In the period T4, both the scan signal SSn-1 and the scan signal SSn have the low-level voltage Vgl, so the sensing voltage VDn-1_m and the sensing voltage VDn_m are reset to the low-level voltage Vgl again. the

In the period T5, the scan signal SSn switches from the low-level voltage Vgl to the high-level voltage Vgh. At this time, because the first touch event occurs at the panel position corresponding to the sensing unit DXn_m, the second capacitance of the sensing unit DXn_m The capacitance value of 233 increases, so the sensing voltage VDn_m is pulled up to the second high voltage Vh2 lower than the first high voltage Vh1, and the second transistor 234 of the sensing unit DXn_m outputs an output corresponding to the second high voltage Vh2 The analog readout signal Sroa_m of the first touch event enables the signal processing circuit 250 to generate the touch position signal Spos corresponding to the first touch event. In the period T6, the scan signal SSn-1 is switched from the low-level voltage Vgl to the high-level voltage Vgh. At this time, because the second touch event occurs at the panel position corresponding to the sensing unit DXn-1_m, the sensing unit DXn The capacitance value of the second capacitor 233 of -1_m increases, so the sensing voltage VDn-1_m is pulled up to the third high voltage Vh3 lower than the first high voltage Vh1, and the second transistor 234 of the sensing unit DXn-1_m is The analog readout signal Sroa_m corresponding to the second touch event is output according to the third high voltage Vh3 , so that the signal processing circuit 250 can generate the touch position signal Spos corresponding to the second touch event. the

FIG. 4 is a schematic diagram of a second embodiment of a liquid crystal display device with touch sensing function according to the present invention. As shown in FIG. 4 , the liquid crystal display device 300 is similar to the liquid crystal display device 200 shown in FIG. 2 , the main difference being that the signal processing circuit 250 is replaced by the signal processing circuit 350 . The signal processing circuit 350 includes a plurality of switches 355 , a multiplexer 370 , a comparator 360 , a storage unit 380 , and a signal positioning unit 390 . Each switch 355 is electrically connected to the corresponding readout line 220 for resetting the voltage corresponding to the analog readout signal to the low power supply voltage Vss. The multiplexer 370 is electrically connected to the plurality of readout lines 220 for sequentially outputting a plurality of analog readout signals to the comparator 360 . Please note that the multiplexer 270 shown in FIG. 2 is a digital multiplexer, while 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, the negative input terminal is electrically connected to the multiplexer 370 to receive analog readout signals in sequence, and the output terminal is electrically connected to The storage unit 380 is configured to output a digital readout signal generated by comparing the analog readout signal with the reference voltage Vref. In another embodiment, the positive input terminal of the comparator 360 is electrically connected to the multiplexer 370 to sequentially receive the analog readout signal, and the negative input terminal of the comparator 360 is used to receive the reference voltage Vref. The storage unit 380 is electrically connected to the comparator 360 and used for storing the digital readout signals sequentially generated by the comparator 360 . The signal positioning unit 390 is electrically connected to the storage unit 380 and used for generating a touch position signal Spos according to a plurality of digital readout signals. The remaining functional operations of the liquid crystal display device 300 are similar to those of the liquid crystal display device 200 , and will not be repeated here. the

FIG. 5 is a schematic diagram of a third embodiment of the liquid crystal display device with touch sensing function of the present invention. As shown in FIG. 5 , the liquid crystal display device 400 is similar to the liquid crystal display device 200 shown in FIG. 2 , the main difference is that the plurality of sensing units 230 are replaced with a plurality of sensing units 330 . The internal structure of the sensing unit 330 is similar to the sensing unit 230 shown in FIG. 2 , the main difference is that a third transistor 235 is provided to control the output operation of the analog readout signal according to the scanning signal. The third transistor 235 includes a first terminal, a second terminal and a gate terminal, wherein the first terminal is electrically connected to the second terminal of the second transistor 234, the gate terminal is electrically connected to the scanning line 201 to receive the scanning signal, and the second terminal is electrically connected to on the readout line 220 . The third transistor 235 can be a thin film transistor or a field effect transistor. When the scan signal has a low-level voltage, the third transistor 235 is in an off state to disable the output of the analog readout signal, that is, the third transistor 235 is used to assist the second transistor 234 to stop outputting the analog readout. Signal. Alternatively, when the scan signal has a high-level voltage, the third transistor 235 is in a conductive state so as to simulate the output operation of the read signal. The remaining functions and operations of the liquid crystal display device 400 are similar to those of the liquid crystal display device 200 , and will not be repeated here. the

FIG. 6 is a schematic diagram of a fourth embodiment of a liquid crystal display device with a touch sensing function according to the present invention. As shown in FIG. 6 , the liquid crystal display device 500 is similar to the liquid crystal display device 400 shown in FIG. 5 , the main difference is that the signal processing circuit 250 is replaced by the signal processing circuit 350 . The internal structure and functional operation of the signal processing circuit 350 have been described in detail in the description of the liquid crystal display device 300 , and will not be repeated here. the

FIG. 7 is a schematic diagram of a fifth embodiment of the liquid crystal display device with touch sensing function of the present invention. As shown in FIG. 7 , the liquid crystal display device 600 includes a plurality of scanning lines 601, a plurality of data lines 602, a plurality of gate lines 603, a plurality of pixel units 605, a plurality of readout lines 620, a plurality of sensing units 630, and a signal processing circuit 250 . Each scan line 601 is used to transmit a corresponding scan signal. Each data line 602 is used to transmit a corresponding data signal. Each gate line 603 is used to transmit a corresponding gate signal. Please note that the frequency of the gate signal can be the same as or different from the frequency of the scan signal, the high level voltage of the gate signal can be the same as or different from the high level voltage of the scan signal, and the low level voltage of the gate signal can be The same or different from the low-level voltage of the scan signal. Each pixel unit 605 includes a pixel transistor Qpx2 , a liquid crystal capacitor Clc2 and a storage capacitor Cst2 . The pixel transistor Qpx2 can be a thin film transistor or a field effect transistor. The pixel transistor Qpx2 includes a first terminal, a second terminal and a gate terminal, wherein the first terminal is electrically connected to the corresponding data line 602 to receive the corresponding data signal, the gate terminal is electrically connected to the corresponding gate line 603 to receive the corresponding gate signal, and the second terminal is electrically connected to the corresponding gate line 603 to receive the corresponding gate signal. The two terminals are electrically connected to the liquid crystal capacitor Clc2 and the storage capacitor Cst2. The pixel transistor Qpx2 is used to control the writing operation of the corresponding data signal according to the corresponding gate signal, and the pixel unit 605 outputs the corresponding image signal according to the written corresponding data signal. Each readout line 620 is electrically connected to a plurality of corresponding sensing units 630 for transmitting corresponding analog readout signals. The internal structure and functional operation of the signal processing circuit 250 have been described in detail in the description of the liquid crystal display device 200 and will not be repeated here. the

In the embodiment shown in FIG. 7 , each pixel unit 605 is adjacent to a sensing unit 630 . In another embodiment, the sensing unit 630 can be arranged at intervals between multiple gate lines 603 or at intervals between multiple data lines 602 , that is, not every pixel unit 605 is adjacent to the sensing unit 630 . Similarly, the scan lines 601 can be correspondingly arranged at intervals of a plurality of gate lines 603 , and the readout lines 620 can be correspondingly arranged at intervals of a plurality of data lines 602 . Each sensing unit 630 includes a first transistor 631 , a first capacitor 632 , a second capacitor 633 , and a second transistor 634 . The first transistor 631 and the second transistor 634 can be thin film transistors or field effect transistors. The coupling relationship of each element and the operating principle of the circuit are described below according to the sensing unit DYn_m. the

The first transistor 631 includes a first terminal, a second terminal and a gate terminal, wherein the first terminal is electrically connected to the scan line SLn to receive the scan signal SSn, and the second terminal is electrically connected to the gate terminal. The first capacitor 632 includes a first terminal and a second terminal, wherein the first terminal is electrically connected to the scan line SLn, and the second terminal is electrically connected to the second terminal of the first transistor 631 . In a preferred embodiment, the second terminal of the first capacitor 632 is directly connected to the gate terminal of the first transistor 631, thereby reducing the layout area of the circuit. The second capacitor 633 includes a first terminal and a second terminal, wherein the first terminal is electrically connected to the second terminal of the first transistor 631 , and the second terminal is used to receive the shared voltage Vcom. The second transistor 634 includes a first terminal, a second terminal and a gate terminal, wherein the first terminal is electrically connected to the scan line SLn, the second terminal is electrically connected to the readout line RLm, and the gate terminal is electrically connected to the first terminal of the second capacitor 633. terminal to receive the sensing voltage VDn_m. The functions of the first transistor 631, the first capacitor 632, the second capacitor 633 and the second transistor 634 are similar to those of the first transistor 231, the first capacitor 232, the second capacitor 233 and the second transistor 234 shown in FIG. Therefore, the touch sensitivity of the sensing unit DYn_m will not decrease due to the increase of the line resistance of the sensing line RLm. In addition, since the sensing unit 630 is integrated into the display panel including the pixel unit 605 , the appearance of the liquid crystal display device 600 can be made thinner and the production cost thereof can be reduced. the

FIG. 8 is a schematic diagram of a sixth embodiment of the liquid crystal display device with touch sensing function of the present invention. As shown in FIG. 8 , the liquid crystal display device 700 is similar to the liquid crystal display device 600 shown in FIG. 7 , the main difference is that the signal processing circuit 250 is replaced by the signal processing circuit 350 . The internal structure and functional operation of the signal processing circuit 350 have been described in detail in the description of the liquid crystal display device 300 , and will not be repeated here. the

FIG. 9 is a schematic diagram of a seventh embodiment of a liquid crystal display device with touch sensing function according to the present invention. As shown in FIG. 9 , the liquid crystal display device 800 is similar to the liquid crystal display device 600 shown in FIG. 7 , the main difference is that the plurality of sensing units 630 are replaced with a plurality of sensing units 730 . The internal structure of the sensing unit 730 is similar to the sensing unit 630 shown in FIG. 7 , the main difference is that a third transistor 635 is provided to control the output operation of the analog readout signal according to the scan signal. The third transistor 635 includes a first terminal, a second terminal and a gate terminal, wherein the first terminal is electrically connected to the second terminal of the second transistor 634, the gate terminal is electrically connected to the scanning line 601 to receive the scanning signal, and the second terminal is electrically connected to on readout line 620 . The third transistor 635 can be a thin film transistor or a field effect transistor. When the scanning signal has a low-level voltage, the third transistor 635 is in an off state to disable the output of the analog readout signal, that is, the third transistor 635 is used to assist the second transistor 634 to stop outputting the analog readout. Signal. Alternatively, when the scan signal has a high-level voltage, the third transistor 635 is in a conductive state so as to simulate the output operation of the read signal. The remaining functional operations of the liquid crystal display device 800 are similar to those of the liquid crystal display device 600 , and will not be repeated here. the

FIG. 10 is a schematic diagram of an eighth embodiment of a liquid crystal display device with touch sensing function according to the present invention. As shown in FIG. 10 , the liquid crystal display device 900 is similar to the liquid crystal display device 800 shown in FIG. 9 , the main difference is that the signal processing circuit 250 is replaced by the signal processing circuit 350 . The internal structure and functional operation of the signal processing circuit 350 have been described in detail in the description of the liquid crystal display device 300 in FIG. 4 , and will not be repeated here. the

FIG. 11 is a flow chart of the touch sensing method of the present invention. The process 990 shown in FIG. 11 is a touch sensing method based on the liquid crystal display devices 200 - 900 according to the above-mentioned first to eighth embodiments of the present invention. The touch sensing method shown in process 990 includes the following steps:

Step S910: providing a scan signal with a low level voltage to the scan line during the first period;

Step S915: During the first period, the sensing unit resets the sensing voltage to a low level voltage according to the scanning signal;

Step S920: providing a scan signal with a high level voltage to the scan line during the second period;

Step S925: During the second period, the sensing unit pulls up the sensing voltage according to the high-level voltage of the scanning signal, wherein the increase of the sensing voltage is controlled by the touch event;

Step S930: During the second period, the sensing unit provides an analog readout signal to feed into the readout line according to the sensing voltage and the scanning signal with a high level voltage;

Step S935: During the second period, the signal processing circuit converts the analog readout signal into a digital readout signal;

Step S940: During the third period, the signal processing circuit generates a touch position signal according to the digital readout signal; and

Step S945: During the third period, the signal processing circuit resets the voltage of the analog readout signal to a low power supply voltage. the

In the process 990 of the above-mentioned touch sensing method, the sensing unit can also disable the output operation of the analog readout signal according to the low-level voltage of the scan signal during the first period, and according to the scan signal during the second period. The high level voltage of the signal enables the output operation of the analog read signal. the

To sum up, 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 second transistor of the sensing unit, thereby controlling the feeding of the high-level voltage of the scanning signal to Input to the readout line to set the voltage of the analog readout signal, so the effect of the sensing voltage will not reduce the performance due to the increase of the line resistance of the readout line, that is, the touch sensitivity will not be affected by the line resistance of the readout line decrease with an increase in resistance. 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 the appearance can be made lighter and thinner, and the production cost can be reduced. the

Although the present invention has been disclosed above with embodiments, it is not intended to limit the present invention. Any person with ordinary knowledge in the technical field of the present invention can make various changes and modifications without departing from the spirit and scope of the present invention. Modification, therefore, the scope of protection of the present invention should be defined by the scope of the appended claims. the

Claims (18)

1. A liquid crystal display device with touch sensing function, comprising: Scanning lines, used to transmit scanning signals; The sensing unit is electrically connected to the scanning line, and is used to provide a first analog readout signal according to the scanning signal, and the sensing unit includes: The first transistor includes a first terminal, a second terminal and a gate terminal, wherein the first terminal is electrically connected to the scan line, and the second terminal is electrically connected to the gate terminal; a first capacitor electrically connected between the scan line and the second terminal of the first transistor; The second capacitor includes a first terminal and a second terminal, wherein the first terminal of the second capacitor is electrically connected to the second terminal of the first transistor, and the second terminal of the second capacitor is used to receive the shared voltage; and The second transistor includes a first terminal, a second terminal and a gate terminal, wherein the first terminal of the second transistor is electrically connected to the scan line, and the gate terminal of the second transistor is electrically connected to the second terminal of the first transistor , the second terminal of the second transistor is used to output the first analog readout signal; and a first readout line, electrically connected to the second end of the second transistor, for transmitting the first analog readout signal; Wherein the capacitance value of the second capacitor changes with a touch event, so as to generate the first analog readout signal corresponding to the touch event. 2. The liquid crystal display device according to claim 1, wherein the first transistor and the second transistor are thin film transistors or field effect transistors. 3. The liquid crystal display device according to claim 1, wherein the sensing unit further comprises: The third transistor includes a first terminal, a second terminal and a gate terminal, wherein the first terminal of the third transistor is electrically connected to the second terminal of the second transistor, and the gate terminal of the third transistor is electrically connected to the scanning line , the second end of the third transistor is electrically connected to the first readout line. 4. The liquid crystal display device according to claim 3, wherein the third transistor is a thin film transistor or a field effect transistor. 5. The liquid crystal display device according to claim 1, further comprising: a second readout line, used to transmit a second analog readout signal; a first switch, electrically connected to the first readout line, for resetting the voltage of the first analog readout signal to a low power supply voltage; a second switch, electrically connected to the second readout line, for resetting the voltage of the second analog readout signal to the low power supply voltage; a first comparator, electrically connected to the first readout line, for comparing the first analog readout signal with a reference voltage to generate a first digital readout signal; and The second comparator, electrically connected to the second readout line, is used for comparing the second analog readout signal with the reference voltage to generate a second digital readout signal. 6. The liquid crystal display device according to claim 5, further comprising: a multiplexer, electrically connected to the first comparator and the second comparator, for sequentially outputting the first digital readout signal and the second digital readout signal; a storage unit, electrically connected to the multiplexer, for storing the first digital readout signal and the second digital readout signal sequentially output by the multiplexer; and The signal positioning unit is electrically connected to the storage unit, and is used for generating a touch position signal according to the first digital readout signal and the second digital readout signal. 7. The liquid crystal display device according to claim 1, further comprising: a second readout line, used to transmit a second analog readout signal; a first switch, electrically connected to the first readout line, for resetting the voltage of the first analog readout signal to a low power supply voltage; a second switch, electrically connected to the second readout line, for resetting the voltage of the second analog readout signal to the low power supply voltage; a multiplexer, electrically connected to the first readout line and the second readout line, for sequentially outputting the first analog readout signal and the second analog readout signal; and a comparator, electrically connected to the multiplexer, used to compare the first analog readout signal with a reference voltage to generate a first digital readout signal, and to compare the second analog readout signal with the reference voltage to generate A second digital readout signal. 8. The liquid crystal display device according to claim 7, further comprising: a memory unit, electrically connected to the comparator, for storing the first digital readout signal and the second digital readout signal sequentially generated by the comparator; and The signal positioning unit is electrically connected to the storage unit, and is used for generating a touch position signal according to the first digital readout signal and the second digital readout signal. 9. The liquid crystal display device according to claim 1, further comprising: data lines for transmitting data signals; and The pixel unit is electrically connected to the scan line and the data line, and is used for outputting an image signal according to the scan signal and the data signal. 10. The liquid crystal display device according to claim 9, wherein the pixel unit comprises: The pixel transistor includes a first terminal, a second terminal and a gate terminal, wherein the first terminal of the pixel transistor is electrically connected to the data line to receive the data signal, and the gate terminal of the pixel transistor is electrically connected to the scan line to receive the scan signal; a liquid crystal capacitor electrically connected to the second end of the pixel transistor; and The storage capacitor is electrically connected to the second end of the pixel transistor. 11. The liquid crystal display device according to claim 1, further comprising: a gate line for transmitting a gate signal; data lines for transmitting data signals; and The pixel unit is electrically connected to the gate line and the data line, and is used to output an image signal according to the gate signal and the data signal. 12. The liquid crystal display device according to claim 11, wherein the pixel unit comprises: The pixel transistor includes a first terminal, a second terminal and a gate terminal, wherein the first terminal of the pixel transistor is electrically connected to the data line to receive the data signal, and the gate terminal of the pixel transistor is electrically connected to the gate line to receive the gate signal; a liquid crystal capacitor electrically connected to the second end of the pixel transistor; and The storage capacitor is electrically connected to the second end of the pixel transistor. 13. The liquid crystal display device according to claim 11, wherein the frequency of the gate signal is different from the frequency of the scan signal. 14. The liquid crystal display device according to claim 11, wherein the high-level voltage of the gate signal is different from the high-level voltage of the scan signal. 15. The liquid crystal display device according to claim 11, wherein the low-level voltage of the gate signal is different from the low-level voltage of the scan signal. 16. A touch sensing method, comprising: A liquid crystal display device with a touch sensing function is provided, and the liquid crystal display device includes: a scanning line for transmitting a scanning signal; a sensing unit electrically connected to the scanning line for providing a first analog reading according to the scanning signal To output a signal, the sensing unit includes: a first transistor, including a first terminal, a second terminal and a gate terminal, wherein the first terminal is electrically connected to the scanning line, and the second terminal is electrically connected to the gate terminal; a capacitor electrically connected between the scan line and the second terminal of the first transistor; a second capacitor including a first terminal and a second terminal, wherein the first terminal of the second capacitor is electrically connected to the first transistor The second end, the second end of the second capacitor is used to receive the shared voltage; and the second transistor includes a first end, a second end and a gate end, wherein the first end of the second transistor is electrically connected to the scan line , the gate terminal of the second transistor is electrically connected to the second terminal of the first transistor, and the second terminal of the second transistor is used to output the first analog readout signal; and the first readout line is electrically connected to the The second terminal of the second transistor is used to transmit the first analog readout signal; wherein the capacitance value of the second capacitor changes with a touch event, so as to generate the first analog corresponding to the touch event read signal; providing the scan signal with a low-level voltage to the scan line during the first period; During the first period, the sensing unit resets a sensing voltage to the low level voltage according to the scan signal; providing the scan signal with a high level voltage to the scan line during the second period; During the second period, the sensing unit pulls up the sensing voltage according to the high-level voltage of the scanning signal, wherein the increase of the sensing voltage is controlled by a touch event; and During the second period, the sensing unit provides the first analog readout signal to be fed into the first readout line according to the sense voltage and the scan signal with the high level voltage. 17. The touch sensing method according to claim 16, wherein the liquid crystal display device further comprises a signal processing circuit, and the touch sensing method further comprises: During the second time period, the signal processing circuit converts the analog readout signal into a digital readout signal; During the third period, the signal processing circuit generates a touch position signal according to the digital readout signal; and During the third period, the signal processing circuit resets the voltage of the analog readout signal to a low power supply voltage. 18. The touch sensing method according to claim 16, further comprising: During the first period, the sensing unit disables the output of the analog readout signal according to the low-level voltage of the scan signal; and During the second period, the sensing unit enables the output of the analog readout signal to operate according to the high-level voltage of the scan signal.

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