CN203300198U - Touch driving circuit and liquid crystal panel - Google Patents

Abstract

The embodiment of the utility model provides a touch drive circuit and a liquid crystal panel. It is used to solve the error problem caused by poor uniformity of component parameters in the touch drive circuit and improve the reliability of the touch screen. The touch driving circuit includes: a photoelectric generating unit, an amplifying unit, an output control unit and an amplifying control unit.

Description

Touch driving circuit and liquid crystal panel

Technical Field

The utility model relates to a liquid crystal display technology especially relates to a touch drive circuit, liquid crystal display panel.

Background

The technology of integrating a Touch Screen Panel (TSP) in a TSP in Cell in a liquid crystal box is to manufacture an inductor (Sensor) and a driving circuit of the Touch Screen on an Array substrate by using an Array (Array) process. The TSP Sensor is integrated in a Liquid Crystal Display (LCD) panel Liquid Crystal box LCDPanel cell, so that the product is light and thin, the functions are diversified, and the reliability of the touch screen is effectively improved.

Fig. 1 shows a basic optical sensing type touch driving circuit in the prior art, wherein a Sensor senses light by using a photodiode D1 to generate leakage current to detect a touch signal. A TFT (Thin-Film Transistor) T1 is used as an amplifying Transistor to enhance the output driving capability of the touch driving circuit, so that the TSP external readout circuit can correctly read the detection result. The circuit exists for each pixel in the liquid crystal cell, where VINI is the initialization level and OUPUT is the data readout line. Each row of pixels in the liquid crystal panel is provided with a row of initialization signal lines for driving each touch driving circuit through the VINI, and each column of pixels is provided with a column of data reading lines for reading touch signals through the OUTPUT.

In the existing technology, a panel circuit is manufactured by using an LTPS (Low Temperature polysilicon) technology, and the uniformity of parameters of components produced by the technology is poor, so that level gains of amplifying transistors of various touch driving circuits are inconsistent, and touch signals amplified and output under the same touch condition are different in size, so that errors exist in the process of reading the touch signals.

SUMMERY OF THE UTILITY MODEL

The embodiment of the utility model provides a touch drive circuit, liquid crystal display panel for solve the error problem when reading touch signal, improve the touch-sensitive screen reliability.

The embodiment of the utility model provides a touch drive circuit, including photoelectricity generation unit, amplification unit, output control unit and amplification control unit; the photoelectric generation unit is connected between the initialization signal line and the amplification control unit, and the amplification control unit is connected between the pixel grid scanning signal line of the current row and the pixel grid scanning signal line of the previous row, and is connected with the photoelectric generation unit, the amplification unit and the output control unit; the photoelectric generation unit is used for receiving the level of the initialization signal line when the grid scanning signal of the pixel in the row is at a first level and the grid scanning signal of the pixel in the previous row is at a second level, wherein the first level is input into the initialization signal line, and then the initialization level is input, so that the level of a connection point of the amplification control unit and the amplification unit is the sum of the initialization level and the conduction voltage of the amplification unit; and the signal processing unit is used for reducing the level of a connection point of the amplification control unit and the amplification unit if the photoelectric generation unit does not sense touch when the grid scanning signal of the pixel in the row is at a second level, the grid scanning signal of the pixel in the previous row is at the second level and the initialization signal line is input into the initialization level; the amplifying unit is connected between the initialization signal line and the output control unit and is connected with the amplifying control unit through the connecting point; the output control unit is used for outputting current to the output control unit according to the level of the connection point; the output control unit is connected between the data output line and the amplifying unit and is connected with the scanning signal line of the grid electrode of the pixel on the previous row; when the grid scanning signal of the pixel in the row is at the second level, the grid scanning signal of the pixel in the previous row is at the first level and the initialization signal line inputs the initialization level, the output current of the amplifying unit is output to the data output line; wherein the initialization level is between a first level and a second level.

An embodiment of the utility model provides a liquid crystal display panel, including the pixel cell, still include touch drive circuit.

According to the technical scheme, the utility model discloses a change the level of the tie point of amplification control unit and amplification unit into the sum of initialization level and the turn-on voltage of amplification unit for the current of amplification unit to output control unit output is a function irrelevant with the turn-on voltage of amplification unit, and the output current that the data output line read can not change according to the difference of components and parts own parameter; therefore, whether the photoelectric generation unit senses touch or not can be accurately judged according to the output current read by the data output line. The utility model provides an error problem when touch signal reads has improved the touch-sensitive screen reliability.

Drawings

FIG. 1 is a schematic diagram of a basic photo-sensing type touch driving circuit in the prior art;

fig. 2 is a schematic diagram of a touch driving circuit according to an embodiment of the present invention;

fig. 3 is a schematic diagram of another touch driving circuit provided in an embodiment of the present invention;

fig. 4 is a schematic circuit diagram of a pixel unit integrated with a touch driving circuit according to an embodiment of the present invention;

fig. 5 is a schematic diagram of a display unit array according to an embodiment of the present invention;

fig. 6 is a timing diagram of driving provided by the embodiment of the present invention;

fig. 7 is a graph showing the relationship between the level according to the embodiment of the present invention.

Detailed Description

The embodiment of the utility model provides a touch drive circuit, liquid crystal display panel for solve the error problem when reading touch signal that the poor result in of components and parts parameter homogeneity, improve the touch-sensitive screen reliability.

Referring to fig. 2, an embodiment of the present invention provides a touch driving circuit, including: a photoelectric generation unit 21, an amplification control unit 22, an amplification unit 23, and an output control unit 24;

the photoelectric generation unit 21 is connected between the initialization signal line VINI and the amplification control unit 22;

the amplification control unit 22 is connected between the pixel gate scanning signal line G _ n of the present row and the pixel gate scanning signal line G _ n-1 of the previous row, and is connected with the photoelectric generation unit 21, the amplification unit 23, and the output control unit 24; the photoelectric generation unit 21 is configured to receive the level of the initialization signal line VINI _ n when the gate scanning signal G _ n of the pixel in the current row is at the first level and the gate scanning signal G _ n-1 of the pixel in the previous row is at the second level, where the initialization signal line VINI _ n inputs the first level first and then inputs the initialization level VINI, so that the level of the connection point P _ n between the amplification control unit 22 and the amplification unit 23 is the sum of the initialization level and the on-state voltage of the amplification unit; and the circuit is used for reducing the level of a connection point P _ n of the amplification control unit and the amplification unit if the photoelectric generation unit does not sense touch when the pixel grid scanning signal G _ n of the row is at a second level, the pixel grid scanning signal G _ n-1 of the previous row is at a second level and the initialization signal line VINI _ n inputs the initialization level VINI;

the amplifying unit 23 is connected between the initialization signal line VINI _ n and the output control unit 24, and is connected to the amplifying control unit 22 through the connection point P _ n; for outputting a current to the output control unit 24 according to the level of the connection point P _ n;

the output control unit 24 is connected between the DATA output line DATA _ TSP and the amplifying unit 23, and is connected to the previous row pixel gate scanning signal line G _ n-1; when the pixel grid scanning signal G _ n of the current row is at the second level, the pixel grid scanning signal G _ n-1 of the previous row is at the first level, and the initialization signal line VINI _ n inputs the initialization level VINI, the output current of the amplifying unit is output to the DATA output line DATA _ TSP;

wherein the initialization level is between a first level and a second level.

Preferably, the photovoltaic generation unit 21 includes: a photodiode D1; two electrodes of the photodiode D1 are respectively connected with an initialization signal line VINI _ n and a connection point P _ n of the amplification control unit and the amplification unit. Among them, D1 can generate reverse leakage current when it is illuminated, i.e. when no touch is sensed.

Preferably, the amplifying unit 23 includes: a first transistor T1; the gate of the first transistor T1 is connected to the connection point P _ n of the amplification control unit and the amplification unit, and the other two electrodes are respectively connected to the initialization signal line VINI _ n and the output control unit 24; the turn-on voltage of the amplifying unit is the threshold voltage V of T1_{th_T1}。

Preferably, the amplification control unit 22 includes: a second transistor T2 and a capacitor C1; the gate of the second transistor T2 is connected to the pixel gate scanning signal line G _ n of the current row, and the other two electrodes are respectively connected to the connection point P _ n of the amplification control unit and the amplification unit and the output control unit 24; two ends of the capacitor are respectively connected with a connection point P _ n of the amplification control unit and the amplification unit and a last row of pixel grid scanning signal line G _ n-1.

Preferably, the output control unit 24 includes: a third transistor T3; the third transistor T3 has a gate connected to the previous row pixel gate scanning signal line G _ n-1 and two electrodes connected to the DATA output line DATA _ TSP and the amplifying unit 23, respectively.

In fig. 2, T1, T2, and T3 are N-type transistors, and the anode of D1 is connected to VINI _ N and the cathode is connected to P _ N. Another embodiment of the present invention is shown in fig. 3, where T1, T2, and T3 are P-type transistors, the cathode of D1 is connected to VINI _ n, and the anode is connected to P _ n.

Preferably, the transistor is a Thin Film Transistor (TFT).

Preferably, the first level is a turn-on level of the transistor, and the second level is a turn-off level of the transistor.

The utility model provides a liquid crystal display panel, including the pixel cell, still include touch drive circuit.

As shown in fig. 4, it is a schematic circuit diagram of a pixel unit including the touch driving circuit in the liquid crystal panel provided in the embodiment of the present invention; where LCD _ Part is an existing pixel unit, DATA _ LCD is a DATA line of the existing pixel unit, and the touch driving circuit portion TSP _ Part may be replaced with a touch driving circuit using P-type transistors.

Fig. 5 is a schematic diagram of a display cell array of a liquid crystal panel according to an embodiment of the present invention; the touch driving circuit part can be replaced by a touch driving circuit using P-type transistors.

The embodiment of the utility model provides a touch drive circuit is in the time of every Frame (Frame), including three working phase, be initialization Initial stage, sensing PHOTO stage, Read stage respectively, its drive process as follows:

an initialization stage: the grid scanning signal line of the pixel of the row inputs a first level, the grid scanning signal line of the pixel of the previous row inputs a second level, the initialization signal line inputs the first level firstly and then inputs the initialization level, so that the level of the connection point of the amplification control unit and the amplification unit is the sum of the initialization level and the conduction voltage of the amplification unit;

a sensing stage: the grid scanning signal line of the pixel of the row inputs a second level, the grid scanning signal line of the pixel of the previous row inputs a second level, the initialization signal line inputs an initialization level, and if the photoelectric generation unit does not sense touch, the level of a connection point of the amplification control unit and the amplification unit is reduced;

a reading stage: the grid scanning signal line of the pixel in the row inputs a second level, the grid scanning signal line of the pixel in the previous row inputs a first level, the initialization signal line inputs an initialization level, and the output control unit outputs the current output by the amplification unit according to the level of the connection point to the data output line;

wherein the initialization level is between a first level and a second level.

Preferably, the first level is a transistor turn-on level, and the second level is a transistor turn-off level.

As shown in fig. 6, which is a driving timing diagram of the liquid crystal panel when the N-type transistor is used, the first level is a high level VDD, and the second level is a low level VSS; where VDD > VINI > VSS, as shown in FIG. 7.

When the P-type transistor is used, the first level < the initialization level < the second level in the driving timing of the touch driving circuit.

The operation of the touch driving circuit is further described with reference to the formula and the driving timing of fig. 6.

An initialization stage: g _ n input VDD, G _ n-1 input VSS, T2 on, T3 off, VINI _ n charges C1 through D1, and P _ n has a level of VDD-V_{th_D}Wherein V is_{th_D}Is the threshold voltage of D1. Then, the level of the VINI _ n jumps to VINI, the gate and the drain of the T1 are short-circuited and equivalent to a diode, and the C1 discharges the VINI _ n through the T1 until the level of the P _ n is VINI + V_{th_T1}Wherein V is_{th_T1}In order to amplify the threshold voltage of the transistor T1, the purpose of the initialization phase is to change the level of the connection point of the amplification control unit and the amplification unit to the sum of the initialization level and the transistor threshold voltage.

A sensing stage: this phase takes most of the time in one frame, G _ n-1 both input VSS, T2, T3 are turned off, and the touch state of the Panel is detected by D1. When the panel in the area corresponding to D1 is touched by a finger (With Touch), the external light source cannot irradiate D1, so that the light receiving amount of D1 is small, the photo-induced leakage current is small, the P _ n level is almost unchanged, and the level is denoted as VINI + V_{th_T1}. When the panel is not touched by a finger (Without Touch), an external light source can irradiate the D1, and the D1 receives light to generate larger light-induced leakage current. Let the level change of P _ n after the photodiode D1 leaks current be Δ V_LEAKThen the level of P _ n is VINI + V_{th_T1}-ΔV_LEAK。

A reading stage: to bias the amplifying transistor T1 in the saturation amplification region where the gain is maximum, the peripheral readout circuit reads out the detection result when G _ n-1 inputs VDD. G _ n-1 input VDD, G _ n input VSS, T2 is off, T1 operates in the saturation amplification region, T3 is on,the current amplified by T1 is output to DATA _ TSP. G _ n-1 jumps from VSS to VDD, i.e., Δ V_BOOSTIf the voltage level of the amplifying transistor T1 in the readout stage, that is, the level of P _ n, is VINI + V = VDD-VSS_{th_T1}-ΔV_LEAK+ΔV_BOOST. Obtaining the amplified current I output from T1 to T3 according to the relation formula of the gate level and the output current of the transistor in the saturated amplification region_{DS_T1}Comprises the following steps:

$I_{\mathrm{DS}\_\mathrm{<figure-callout\; id="1"\; label="T"\; filenames="HDA00003414319900011.png,HDA00003414319900012.png"\; state="\{\{state\}\}">T</figure-callout>}1}=\frac{1}{2}\&CenterDot;K\&CenterDot;{(\mathrm{VINI}+V_{\mathrm{th}\_T1}-{\mathrm{\&Delta;V}}_{\mathrm{LEAK}}+{\mathrm{\&Delta;V}}_{\mathrm{BOOST}}-V_{\mathrm{th}\_T1})}^2$

$=\frac{1}{2}\&CenterDot;K\&CenterDot;{(\mathrm{VINI}-{\mathrm{\&Delta;V}}_{\mathrm{LEAK}}+{\mathrm{\&Delta;V}}_{\mathrm{BOOST}})}^2$

wherein K is a constant.

Since the level of P _ n is adjusted in advance during the initialization phase, V is eliminated from the current formula of the amplified output of the transistor T1_{th_T1}The influence of (c). Therefore, the situation that different current magnitudes are read by the DATA _ TSP in the same touch scene is avoided, and the reliability of the read amplified signal is improved.

To sum up, the embodiment of the utility model provides a touch drive circuit, liquid crystal display panel for solve the components and parts parameter and be the poor touch signal's that leads to of transistor threshold voltage homogeneity error problem, improve the touch-sensitive screen reliability.

It will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims and their equivalents, the present invention is also intended to include such modifications and variations.

Claims (7)

1. A touch driving circuit, comprising: the photoelectric generating unit, the amplifying unit, the output control unit and the amplifying control unit; wherein,

the photoelectric generation unit is connected between the initialization signal line and the amplification control unit,

the amplifying control unit is connected between the grid scanning signal line of the pixel of the current row and the grid scanning signal line of the pixel of the previous row, and is connected with the photoelectric generation unit, the amplifying unit and the output control unit; the photoelectric generation unit is used for receiving the level of the initialization signal line when the grid scanning signal of the pixel in the row is at a first level and the grid scanning signal of the pixel in the previous row is at a second level, wherein the first level is input into the initialization signal line, and then the initialization level is input, so that the level of a connection point of the amplification control unit and the amplification unit is the sum of the initialization level and the conduction voltage of the amplification unit; and the signal processing unit is used for reducing the level of a connection point of the amplification control unit and the amplification unit if the photoelectric generation unit does not sense touch when the grid scanning signal of the pixel in the row is at a second level, the grid scanning signal of the pixel in the previous row is at the second level and the initialization signal line is input into the initialization level;

the amplifying unit is connected between the initialization signal line and the output control unit and is connected with the amplifying control unit through the connecting point; the output control unit is used for outputting current to the output control unit according to the level of the connection point;

the output control unit is connected between the data output line and the amplifying unit and is connected with the scanning signal line of the grid electrode of the pixel on the previous row; when the grid scanning signal of the pixel in the row is at the second level, the grid scanning signal of the pixel in the previous row is at the first level and the initialization signal line inputs the initialization level, the output current of the amplifying unit is output to the data output line;

wherein the initialization level is between a first level and a second level.

2. The circuit of claim 1, wherein the photo-generation unit comprises: a photodiode; two poles of the photodiode are respectively connected with an initialization signal line and a connection point of the amplification control unit and the amplification unit.

3. The circuit of claim 1, wherein the amplification unit comprises: a first transistor; the grid electrode of the first transistor is connected with the connection point of the amplification control unit and the amplification unit, and the other two poles of the first transistor are respectively connected with the initialization signal line and the output control unit.

4. The circuit of claim 1, wherein the amplification control unit comprises: a second transistor and a capacitor;

the grid electrode of the second transistor is connected with the grid electrode scanning signal line of the pixel of the row, and the other two poles of the second transistor are respectively connected with the connection point of the amplification control unit and the amplification unit and the output control unit;

and two ends of the capacitor are respectively connected with the connection point of the amplification control unit and the amplification unit and the scanning signal line of the last row of pixel grid electrodes.

5. The circuit of claim 1, wherein the output control unit comprises: a third transistor;

the grid electrode of the third transistor is connected with the grid electrode scanning signal line of the last row of pixels, and the other two poles of the third transistor are respectively connected with the data output line and the amplifying unit.

6. A circuit as claimed in any one of claims 2 to 5, wherein the first level is the turn-on level of the transistor and the second level is the turn-off level of the transistor.

7. A liquid crystal panel comprising a pixel cell, characterized by further comprising the touch drive circuit of claims 1-6.

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