WO2015058350A1

WO2015058350A1 - Self-capacitance change detection method and self-capacitance sensing device for touch screen

Info

Publication number: WO2015058350A1
Application number: PCT/CN2013/085653
Authority: WO
Inventors: 莫良华; 刘卫平
Original assignee: 敦泰科技有限公司
Priority date: 2013-10-22
Filing date: 2013-10-22
Publication date: 2015-04-30

Abstract

Proposed are a self-capacitance change detection method and a self-capacitance sensing device for a touch screen, wherein the self-capacitance sensing device comprises a rectangular electrode and a self-capacitance change detection unit which is provided with a variable acquisition module. The variable acquisition module comprises a constant current source, a clamping circuit and a charge transceiving detection circuit which are electrically connected to a first node, and a grounded second node. In a detection process for one electrode, a first node of the variable acquisition module is first electrically connected to a first end of the electrode, and a second node is electrically connected to a second end of the electrode; after a first self-capacitance variable is acquired, the first node of the variable acquisition module is then electrically connected to the second end of the electrode, and the second node is electrically connected to the first end of the electrode, so as to acquire a second self-capacitance variable. The self-capacitance sensing device in the present invention has the characteristics of simple production process, high production efficiency, good electrode reliability, not being easy to break, wide scope of application of electrode materials, and good anti-electro-static discharge (ESD) performance.

Description

Self-capacitance change detecting method for touch screen and self-capacitance sensing device

The present invention relates to a method for detecting a sensing signal and a device for implementing the same, and more particularly to a method for converting a touch information into a self-capacitance variation for a touch screen and a device for implementing the method. Background technique

The self-capacitive touch screen is a type of capacitive touch screen based on a self-capacitance sensing device. The capacitive sensing device converts the touch information of the touch screen into a self-capacitance change signal, and determines the touch position coordinates according to the self-capacitance change signal. The self-capacitance sensing device can be used not only to manufacture a stand-alone touch screen, but also in a related device, for example, by incorporating a self-capacitance sensing device on a display device to form a touch display screen. The self-capacitance sensing device has been widely used in smart machines and tablet computers because it requires only a single layer layout and wiring, has a simple production process, high yield, and low cost. The electrode arrangement structure diagram of the prior art single-layer self-capacitance sensing device is shown in FIG. 12, and a triangular or triangular-like electrode 91 is used, and each electrode 91 is disposed in pairs to form a complementary electrode pair 92, and each electrode pair 92 is repeatedly stacked. And the screen that covers the entire touch screen or display screen. As is apparent from the electrode arrangement shown in Fig. 12, there is no crossover between the electrodes 91, which makes the production process relatively simple. The prior art self-capacitance sensing device further includes a self-capacitance detecting unit electrically connected to each of the electrodes 91.

Figures 13 and 14 show the basic principle of self-capacitance detection. The electrode 91 is usually covered with a cover 93 made of a transparent insulating dielectric material. The self-capacitance of the self-capacitance sensing device, that is, the capacitance of the electrode 91 to the ground, is Cp as shown in FIG. When the human body 94 touches the cover plate 93, since the human body approximates a ground, it corresponds to a capacitance Cf connected to the ground on the electrode 91, thereby increasing the self-capacitance of the electrode 91 to the ground, as shown in FIG. 13 and FIG. 14 is shown. By detecting the change in self-capacitance, it is possible to determine whether a touch has occurred.

As shown in Fig. 12, the electrode 91 with the long base on the left side is 911L, 912L 91 ( M _ 1 ) L, 91ML,

91 ( M+1 ) L, ... number, the electrode with the long base on the right side 91 presses 911R, 912R 91 ( M _ 1 ) R, 91MR,

91 ( M+1 ) R, ... number, M represents a natural number. The two electrodes 91 of the same numerical number constitute an electrode pair. For example, the electrodes 91 numbered 91ML and 91MR constitute an electrode pair. The self-capacitance detecting unit detects the amount of change in self-capacitance of each electrode 91 when a touch occurs. Touch point 99 causes self-capacitance changes of six electrodes 91, which are numbered 91 (M - 1) L, 91ML, 91 (M+l) L, 91 (M - 1) R, 91MR, and 91 (M+ l) R. Accordingly, the amounts of self-capacitance change are Dpl, Dp2, Dp3, Dp4, Dp5, and Dp6, respectively. First find out the channel with the largest change in the longitudinal direction as the touch Touch the channel that occurs, that is, the change amount is Dp2, the number is 91ML corresponding to the electrode 91 channel, combined with the change amount of the upper and lower channels, find the position of the center of gravity, which is the vertical axis coordinate of the touch point; The ratio of the amount of change of the opposite triangular electrode is the coordinate in the direction of the horizontal axis.

The prior art self-capacitance sensing device also has the following defects and deficiencies:

1. The production process is complicated; the electrode 91 of the prior art self-capacitance sensing device is generally unable to make a true triangle in actual production, but is replaced by a triangular-shaped trapezoid; in order to obtain better precision in the X-axis direction Generally, the narrow side of the trapezoid is required. For example, the number shown on the right side of the electrode 91 of the 911L is as shown in Fig. 12. The smaller the width, the better, usually required to be 0.3 mm or less, which has certain requirements on the process capability and becomes a production cost. One of the factors of reduction;

2. There are many production processes; the smallest detection unit of the traditional structure is a pair of triangles, and in order to improve the linearity of the line, each triangle is also split into two or more small triangles in parallel, such an electrode structure, for the laser In terms of process, it needs to be cut many times, which becomes another factor that affects the reduction of production cost;

3. For a touch screen module using a soft substrate, for example, a substrate made of a film material, if the electrode 91 of the prior art self-capacitance sensing device is used on such a substrate, due to the tip of the triangular electrode 91 Very thin, if the substrate is bent during production, transportation, and testing, it may cause the transparent conductive material used in the electrode area to make the electrode, such as Indium Tin Oxide, which causes the self-capacitance sensing device to break. Even the touch screen is damaged; the fragile structure of the triangular electrode 91 is also a factor that affects the production cost reduction;

4. The electrode material is required to be high; for some new materials for manufacturing the electrode 91, such as a metal mesh material, in order to ensure good bonding between the wires constituting the metal mesh, the minimum width of the electrode 91 is higher than that of the existing indium tin oxide. The ITO material should be larger than lmm, which is difficult to accept for the prior art triangular electrode 91 for manufacturing a self-capacitance sensing device;

5. Antistatic discharge Electro-Static Discharge performance is poor; For the existing mainstream transparent conductive material indium tin oxide ITO, its impedance is large, if an electrostatic discharge ESD event occurs, in the area where the indium tin oxide ITO width is small, such as the width Below 0.1 mm, ESD is more likely to occur due to electrostatic discharge, resulting in a short circuit between the indium tin oxide ITO electrodes. Summary of the invention

The technical problem to be solved by the present invention is to avoid the deficiencies of the prior art and to propose a self-capacitance change detecting method for a touch screen, and a self-capacitance sensing device using the same, by using an improved electrode structure, using a new one The self-capacitance detection method reduces the production cost of the self-capacitance sensing device and improves its overall performance.

The technical problem solved by the present invention can be achieved by using the following technical solutions:

A self-capacitance change detecting method for a touch screen is proposed, which is based on a self-capacitance sensing device, and the self-capacitance sensing device At least one electrode is included. The electrode includes a first end and a second end in a first direction. The method performs the following steps for each electrode,

A. a first end of the electrode is electrically connected to the constant current source, the clamp circuit and the charge transceiver detection circuit, and the second end of the electrode is grounded; the constant current source outputs a current of a constant current value to the electrode; The circuit limits the potential of one end of the electrically connected electrode to a constant potential; the charge transceiving detection circuit is capable of outputting a charge or receiving a charge, and detecting a charge output amount or a receiving amount, and quantizing the charge output amount as a self-capacitance change amount;

B. The charge transceiver detection circuit detects whether there is a charge output;

If there is a charge output, the quantized charge output is the first self-capacitance change amount, and then step C is performed;

If there is no charge output, directly perform step E;

C. electrically connecting a constant current source, a clamp circuit and a charge transceiver detection circuit at the second end of the electrode, and grounding the first end of the electrode;

D. The charge transceiving detection circuit quantizes the charge output amount as a second self-capacitance change amount;

E. The self-capacitance change detection for the electrode ends. Specifically, the constant current value outputted by the constant current source to the electrode in step A is I, and the clamp circuit limits the potential of one end of the electrically connected electrode to a constant potential VI, which should satisfy V1/I = R R is the resistance of the electrode connected to the clamp circuit and the constant current source.

The technical problem solved by the present invention can also be achieved by using the following technical solutions:

A self-capacitance sensing device for a touch screen is designed and manufactured, comprising at least one electrode, and a self-capacitance change detecting unit electrically connecting the electrodes. The electrode has a rectangular shape and includes a first end and a second end for electrically connecting the self-capacitance change detecting unit in a direction in which the electrode extends. The self-capacitance change detecting unit includes at least one variable collecting module. The variable set module includes a constant current source electrically coupled to the first node, a clamp circuit and a charge transceiving detection circuit, and a second node that is grounded. In the detecting process for one electrode, the first node of the variable collecting module first electrically connects the first end of the electrode, and the second node electrically connects the second end of the electrode to the first self-capacitance change amount The first node of the variable clamp module is electrically connected to the second end of the electrode, and the second node is electrically connected to the first end of the electrode to collect the second self-capacitance change amount. The clamping circuit limits a potential of one end of the electrically connected electrode to a constant potential, and the constant current source supplies a constant current to the electrically connected electrode; the charge transceiving detection circuit changes to a self-capacitance of the electrically connected electrode thereof The electrode outputs a charge, and detects the amount of charge output, and quantizes the amount of charge output as a change in self-capacitance.

The clamping circuit defines a constant potential defined by the potential of one end of the electrically connected electrode as VI, and the constant current supplied from the constant current source to the electrically connected electrode is I, then V1/I = R should be satisfied, and R is a clamp The electrical resistance of the electrode is electrically connected to the circuit and the constant current source. Specifically, the clamp circuit includes an operational amplifier, and the constant potential defined by the clamp circuit is controlled by an input voltage of a forward input terminal of the operational amplifier. The charge transceiving detection circuit includes the operational amplifier used as a clamp circuit, electrically connected to a charge transceiving capacitor between an inverting input end and an output end of the operational amplifier, and an AC/DC electrically connected to an output end of the operational amplifier Convert submodules. The current output terminal of the constant current source and the inverting input terminal of the operational amplifier are electrically connected to the first node.

In order to reset the circuit state after each detection, a reset switch is electrically connected between both ends of the charge transceiver capacitor. A specific structure of an electrode is that at least one apex angle of the electrode is cut to form a bevel of a straight line, so that the electrode is processed into a rectangular electrode with a beveled edge.

Another specific structure of the electrode is that at least one of the apex angles of the electrodes is cut away to form a circular arc edge, so that the electrode is processed into a rectangular electrode with a circular arc side.

Still another electrode has a specific structure in which at least one side of the electrode is machined with at least two grooves, and convex teeth are formed between the two adjacent grooves, so that the electrodes are processed into rectangular electrodes with serrated edges.

In a specific application, the electrode is made of indium tin oxide, a metal mesh or a carbon nanomaterial.

Regarding the arrangement of the electrodes, the self-capacitance sensing device further includes a substrate made of a resin synthetic film material or made of glass, and the electrodes are attached to the substrate.

When the self-capacitance sensing device is combined with the display device, the self-capacitance sensing device is mounted in the liquid crystal display. The liquid crystal display panel includes a first liquid crystal substrate and a second liquid crystal substrate, and a liquid crystal material, a pixel electrode, a color filter layer, and a black matrix sandwiched between the first liquid crystal substrate and the second liquid crystal substrate. The electrode is attached to an upper layer or a lower layer of the first liquid crystal substrate, or an upper layer or a lower layer of the second liquid crystal substrate.

An electrode scanning detection method, the self-capacitance change detecting unit includes a set of variable collection modules; the set of variable collection modules are electrically connected to the electrodes in a controlled manner according to a set timing, that is, time-sharing and electrical connection Each electrode is detected to complete the change in self-capacitance of each electrode.

In another electrode scanning detection mode, the number of the variable collecting modules is less than the number of electrodes; each variable collecting module is controlled to electrically connect one of the electrodes in a one-to-one manner according to a set timing, that is, Each electrode is electrically connected to the time division sub-region to complete the self-capacitance change detection of each electrode.

It is also possible to use a one-to-one electrode scanning detection method, and the variable collection module electrically connects the electrodes one-to-one. When the self-capacitance sensing device is combined with the display device, the self-capacitance sensing device is mounted in the liquid crystal display. The liquid crystal display is controlled by a display driver circuit chip. The self capacitance change detecting unit is integrated in the display driving circuit chip.

When the self-capacitance sensing device is combined with the display device, in order to coordinate the liquid crystal driving and the self-capacitance detection, the self-capacitance transmission The sensing device also includes a coordinated detection module. The self-capacitance sensing device is mounted in a liquid crystal display. The liquid crystal display is controlled by a display driving circuit. The coordinated detection module electrically connects the self-capacitance change detecting unit and the display driving circuit to complete the respective functions of the self-capacitance change detecting unit and the display driving circuit in a time-dividing and/or sub-region without interfering with each other.

The technical problem of the present invention can be achieved by using the following technical solutions:

As an extension of the data processing in the self-capacitance change detecting method for the touch screen, a touch point coordinate data processing method according to claim 16 is provided, wherein the self-capacitance change detecting method for the touch screen is The electrodes are sequentially arranged in a second direction perpendicular to the first direction, characterized in that the method comprises:

F. When a touch point changes the self-capacitance of the K electrodes, the amount of change in the self-capacitance of the K pair related to the touch point is obtained, that is, the amount of self-capacitance change of 2K;

G. Select the largest of the 2K self-capacitance changes;

The maximum self-capacitance change amount belongs to the T-th electrode in the second direction, and the maximum self-capacitance change amount is the first self-capacitance change amount of the T-th electrode, that is, the DTU, and the other of the T-th electrode The amount of self-capacitance change is the second self-capacitance change of the electrode, that is, DTV,

Therefore, the first self-capacitance variation of each of the electrodes of the T-th electrode along the second direction is D(T+1)U, D(T+2) U, ···, D (T+Wl) U, respectively. And D (T-1) U, D ( T-2 ) U, ..., D ( T-W2 ) U; the second self-capacitance change is D (T + 1) V, D (T + 2) V , ···, D (T+Wl ) V, and D (T-1) V, D ( T-2 ) V, ..., D ( T-W2 ) V, W1+W2+1=K;

H. If the length of each electrode in the first direction is X0 and the length in the second direction is YO, then step Α the touch point along the second direction coordinate Y is

t=T+Wl

^tx(DtU + DtV)

Γ- t=T-W2

t=T+Wl '

^(DtU + DtV)

t=T-W2 Step A The lateral coordinate of the touch point along the first direction X is,

Compared with the prior art, the technical effects of the "self-capacitance change detecting method for a touch screen and a self-capacitance sensing device" of the present invention are as follows:

1. The production process is simple; the electrode shape of the invention is rectangular, and the longitudinal width of the electrode is relatively wide, which reduces the precision of the process. Requirements, can reduce production costs;

2. The production efficiency is high; the electrode shape of the invention adopts a rectangular structure, and the minimum detection unit can be completed by cutting one knife, and the production efficiency is high;

3. The reliability is good and the crack is not easy; the electrode structure of the invention has a rectangular structure, and the width value is relatively large. Even if the substrate to which the electrode is attached is made of a soft material, the electrode is not easily broken when the substrate is bent;

4. The material requirements are low; the electrode structure of the invention has a rectangular structure, and the minimum width value thereof is large, so that the electrode can be made of a metal mesh new material;

5. The antistatic discharge ESD performance is good; the existing mainstream electrode manufacturing material indium tin oxide ITO, the antistatic discharge ESD ability decreases with the decrease of the width, the width value of the electrode in the invention is relatively large, and the antistatic discharge ESD ability is relatively strong. . DRAWINGS

1 is a schematic view showing an electrode arrangement structure of a self-capacitance sensing device of the present invention;

2 is a schematic diagram showing the electrical principle of the self-capacitance sensing device of the present invention;

3 is a schematic diagram showing the electrical principle of the first self-capacitance change amount detection when the self-capacitance sensing device of the present invention is touched; FIG. 4 is a second self-capacitance change amount detection of the self-capacitance sensing device of the present invention when a touch occurs. FIG. 5 is a schematic diagram of an electrical principle of an embodiment of a self-capacitance sensing device of the present invention; FIG.

Figure 6 is a schematic view showing the structure of a rectangular electrode 101 having a beveled edge according to the present invention;

Figure 7 is a schematic view showing the structure of a rectangular electrode 102 having a circular arc side according to the present invention;

Figure 8 is a schematic view showing the structure of a rectangular electrode 103 having a sawtooth edge according to the present invention;

Figure 9 is a schematic view showing the structure of an electrode 10 made of a metal mesh;

FIG. 10 is a schematic diagram showing an example of an electrical principle for detecting each electrode 10 by using a set of variable parameter sets;

Figure 11 is a schematic cross-sectional structural view of a liquid crystal display;

12 is a schematic diagram showing an electrode arrangement structure of a prior art single-layer self-capacitance sensing device;

13 is a schematic diagram of self-capacitance of a prior art self-capacitance sensing device when a touch occurs;

14 is a schematic diagram of an equivalent electrical principle of a prior art self-capacitance sensing device in the event of a touch. detailed description

The embodiments are further described in detail below with reference to the embodiments shown in the drawings.

In order to eliminate the defects of the prior art triangular electrode, such as complicated production process, many production processes, easy breakage, high electrode material requirements and poor antistatic discharge ESD performance, the present invention uses a rectangular electrode. Rectangular electrodes are obviously smaller than triangular electrodes The production process is simplified and the production process is reduced. Since the rectangular electrode has a large longitudinal width, the electrode is attached to the soft substrate, and the substrate is not easily broken even if the substrate is bent; and the larger longitudinal width of the rectangular electrode satisfies the minimum width requirement of the metal mesh material of the metal mesh, The electrode is made of a metal mesh material; also because the rectangular electrode has a large longitudinal width, the antistatic discharge ESD performance of the electrode is also improved. As shown in FIG. 1, the self-capacitance sensing device proposed by the present invention comprises a rectangular electrode 10, and the electrode 10 extends in the direction of the abscissa of the Cartesian coordinate system, and the electrodes 10 are parallel to each other along the ordinate direction of the Cartesian coordinate system. within the area. Of course, the electrode 10 extends in the ordinate direction of the Cartesian coordinate system, and the electrodes 10 are parallel to each other in the direction of the abscissa of the Cartesian coordinate system, which is an equivalent feasible solution. As shown in Fig. 1, for the convenience of the following description, each electrode 10 is identified by SI Sn, where n is a variable whose value is a natural number, and thus the electrode 10 numbered Sn can represent any electrode 10 An electrode 10. Each of the electrodes 10 has two ends in the extending direction, that is, the X-axis direction of the Cartesian coordinate system, and the electrodes 10 each include a first end L and a second end R, and then the electrode 10 of the number S1 has a first end S1L and a second end S2R And so on, the electrode 10 numbered Sn includes a first end SnL and a second end SnR.

As shown in FIG. 2, the self-capacitance sensing device of the present invention further includes a self-capacitance change detecting unit 2 electrically connected to each electrode 10, and the self-capacitance change detecting unit 2 detects the self-capacitance change of each electrode. The self-capacitance conversion detecting unit 2 specifically detects and collects the self-capacitance change amount of the electrode 10 electrically connected to the variable collecting module 21 through the variable collecting module 21. For any of the electrodes 10 numbered Sn, the first end SnL of the electrode 10 is connected to the charge transceiving detection circuit 211, the constant current source 212, and the clamp circuit 213, respectively. The second end SnR of the electrode 10 is connected to the ground. Thus, the charge transceiver detection circuit 211, the constant current source 212, and the clamp circuit 213 are all electrically connected to the first node a of the variable collector module 21, and the second node b of the variable clamp module 21 is grounded. The constant current source 212 flows in or out of a fixed amount of current. The clamp circuit 213 clamps the first node a, i.e., the first terminal SnL terminal of the electrode 10, to a fixed voltage, and the charge transceiver detection circuit 211 can inject or discharge charges and can detect the amount of charge flowing in or out.

The voltage clamped by the clamp circuit 213 is VI, the resistance between the two ends of the electrode 10 is R, and the current of the constant current source 212 is I, and the relationship between them is: V1/R=I. Thus, in the case where no touch occurs, the current I supplied from the constant current source 212 is such that the voltage of the resistance connection current source of the electrode 10 and the first terminal SnL of the clamp circuit is maintained at VI, and the charge transceiving detection circuit 211 does not need to flow in. Or the electric charge is discharged, that is, the electric charge detected by the electric-transmission detecting circuit 211 when the touch is not generated is zero.

The electrode 10 can be equivalently connected in series with k resistors R1, R2, R3 Rj Rk , and the resistance values are equal. The upper nodes of each resistor are 0, 1, 2, ... k-1, respectively, and the last resistor The lower plate node is k, and nodes 0 and k are electrodes respectively.

The first end of 10 is SnL and the second end is SnR.

When the node 0 is connected to the clamp circuit 213-terminal, that is, the first node a is electrically connected to the first end SnL of the electrode 10, and the second node b is electrically connected to the second end SnR of the electrode 10, the voltage of the node 0 is VI. , node k is grounded, then the voltage on node j is: Vj = ^3⁄4Vl , ( 1 ).

k When the node k is connected to the clamp circuit 213-terminal, that is, the first node a is electrically connected to the second end SnR of the electrode 10, and the second node b is electrically connected to the first end SnL of the electrode 10, the voltage of the node k is VI , node 0 is grounded, and the voltage on node j is:

Vj = J-xVl ( 2 ).

k When the node j touches, as shown in Figure 3, this event can be equivalent to a capacitance Ct connected between the touch point j and the ground.

As shown in FIG. 3, when the first end SnL of the electrode 10 is terminated to the clamp circuit 213, that is, the first node a electrically connects the first end SnL of the electrode 10, and the second node b electrically connects the second end SnR of the electrode 10 , by the formula (1), the voltage on Q is

Vj = ^^xVl ,

k then the charge Q1 to be stored on Q is

Ql = ^^xVlxCt , ( 3 ).

Since the constant current source 212 can only supply the current flowing through the resistor string, this charge Q1 is supplied from the charge transceiving detection circuit 211 and can be quantized into the first self-capacitance variation.

After the above detection is completed, the first end SnL of the electrode 10 is changed to ground, and the second end SnR of the electrode 10 is connected to the clamp circuit 212, that is, the first node a electrically connects the second end SnR of the electrode 10, and the second The node b electrically connects the first end SnL of the electrode 10 as shown in FIG. From equation (2), the voltage on Q is:

Vj = J-xVl ,

k then the charge Q2 stored on Ct is

Q2 = xVlxCt ( 4 ).

Since the constant current source 212 can only supply a current flowing through the resistor string, this charge is supplied from the charge transceiving detection circuit 211 and can be quantized into a second self-capacitance variation.

Therefore, the variable collection module 21 obtains two self-capacitance change amount data for the occurrence of the touch electrode 10 to obtain the first self-capacitance change amount and the second self-capacitance change amount.

In this regard, the present invention provides a self-capacitance change detecting method for a touch screen, based on a self-capacitance sensing device, The capacitive sensing device includes at least one electrode. The electrode includes a first end and a second end in a first direction. Specifically, in the embodiment shown in FIG. 1 of the present invention, the first direction is the X-axis direction of the abscissa of the Cartesian coordinate system in the embodiment. The method performs the following steps for each electrode,

If there is a charge output, the quantized charge output or the charge receiving amount is the first self-capacitance change amount, and then step C is performed; the case where the step is apparent is that the electrode is touched;

If there is no charge output, directly perform step E;

E. The self-capacitance change detection for the electrode ends.

The method performs the above steps once for each electrode to complete the self-capacitance change detection for the electrode. It can be seen that in the step B, if no charge output or charge is detected, the detection of the self-capacitance change of the electrode is directly completed. The operation of the first node and the second node being electrically connected to the first end and the second end of the electrode is performed only when the charge output or the received charge is detected, and the detection is continued. Of course, regardless of whether the charge transceiver detection circuit detects the charge output or the received charge, the first node and the second node are electrically connected to the first end and the second end of the electrode in a relatively fixed period of time. And the operation process of continuing the detection should also be an alternative to the above solution of the present invention, and should be within the scope of the present invention.

The constant current value outputted to the electrode by the constant current source in step A is I, and the clamp circuit limits the potential of one end of the electrically connected electrode to a constant potential of VI, and should satisfy V1/I = R, R is the resistance of the electrode to which the clamp circuit and the constant current source are electrically connected.

Based on the above method, the present invention also provides a self-capacitance sensing device for a touch screen, comprising at least one electrode 10, and a self-capacitance change detecting unit 2 electrically connecting the electrodes 10. The electrode 10 has a rectangular shape and includes a first end and a second end for electrically connecting the self-capacitance change detecting unit along the extending direction of the electrode. In the embodiment of the present invention, the direction in which the electrode extends is the direction in which the long side of the rectangular electrode is located, that is, the X-axis direction of the abscissa in the Cartesian coordinate system shown in FIG. The electrode 10 thus includes a first end SnL and a second end SnR. The self-capacitance change detecting unit 2 includes at least one variable set mode Block 21. The variable collection module 21 includes a constant current source 212 electrically coupled to the first node a, a clamp circuit 213 and a charge transceiving detection circuit 211, and a second node b that is grounded. In the detecting process for one electrode 10, the first node a of the variable collecting module 21 is electrically connected to the first end SnL of the electrode 10, and the second node b is electrically connected to the second end SnR of the electrode. After the first self-capacitance change amount, the first node a of the variable clamp module 21 is electrically connected to the second end SnR of the electrode 10, and the second node b is electrically connected to the first end SnL of the electrode 10 to collect the second Self-capacitance change. The clamp circuit 213 limits the potential of the 10th end of the electrically connected electrode to a constant potential, and the constant current source 212 supplies a constant current to the electrically connected electrode 10; the charge transceiving detection circuit 211 is electrically connected to the electrode 10 The self-capacitance changes, the charge is output to the electrode 10, and the charge output amount or the charge receiving amount is detected, and the quantized charge output amount is the self-capacitance change amount.

The clamping circuit defines a constant potential defined by the potential of one end of the electrically connected electrode as VI, and the constant current supplied from the constant current source to the electrically connected electrode is I, then V1/I = R should be satisfied, and R is a clamp The electrical resistance of the electrode is electrically connected to the circuit and the constant current source.

As a method for self-capacitance change detection method for a touch screen, which subsequently converts self-capacitance change amount data into coordinate data, the present invention provides a touch point coordinate data processing method based on the touch screen for step A to step E In the self-capacitance change detecting method, the electrodes are sequentially arranged in a second direction perpendicular to the first direction. In the embodiment of the present invention, the first direction is the X-axis direction of the abscissa of the Cartesian coordinate system shown in Fig. 1, and the second direction is the ordinate Y-axis direction of the Cartesian coordinate system shown in Fig. 1. The method includes:

F. When a touch point changes the self-capacitance of the K electrodes, the amount of self-capacitance change of the K pair related to the touch point is obtained, that is, the amount of self-capacitance change of 2K;

G. Select the largest of the 2K self-capacitance changes;

The maximum self-capacitance change amount belongs to the T-th electrode in the second direction, and the maximum self-capacitance change amount is the first self-capacitance change amount of the T-th electrode, that is, DTU, the other of the T-th electrode The amount of self-capacitance change is the second self-capacitance change of the electrode, that is, DTV,

Therefore, the first self-capacitance change amount of each of the electrodes of the T-th electrode along the second direction is D(T+1)U, D(T+2) U, ···, D(T+Wl) U, respectively. And D ( T-1 ) U, D ( T-2 ) U, ..., D ( T-W2 ) U; the second self-capacitance change is D ( T +1 ) V, D ( T+2 ) V , ··· , D ( T+Wl ) V, and D ( T-1 ) V, D ( T-2 ) V, ..., D ( T-W2 ) V, W1+W2+1=K;

H. If the length of each electrode in the first direction is X0 and the length in the second direction is Υ0, then step Α the touch point along the second direction coordinate Y is

t=T+Wl

^tx(DtU + DtV)

Γ- t=T-W2

t=T+Wl '

^(DtU + DtV) The touch point in step A is along the first direction transverse coordinate X,

t=T+Wl

∑DtV

x= t=T+Wl

^(DtU + DtV)

t=T-W2

The above method is specific to the embodiment of the present invention, and the first and second self-capacitance change amount data collected by the variable collection module 21 are transmitted to a dedicated coordinate data processor unit or data with a coordinate data processing function. processor. Based on the first and second self-capacitance change amount data of the present invention, the touch coordinate data can be obtained by the following specific method according to the above method. As shown in FIG. 1, it is assumed that the touch point affects three adjacent electrodes 10, in the middle. The number of positions is the first self-capacitance change amount D3 and the second self-capacitance change amount D4 of the electrode 10 of Sn in the above two detections, wherein the first self-capacitance change amount D3 is the maximum value of all the changes. Then, the electrode numbered S (n-l) obtains the first self-capacitance change amount D1 and the second self-capacitance change amount D2 in two tests. The two detections of the electrode 10 numbered S (n+1) obtain the first self-capacitance change amount D5 and the second self-capacitance change amount D6. If the length of each electrode 10 along the Y-axis direction of the Cartesian coordinate system is Y0, then the Y-axis coordinate of the touch point is

Y = (Dl + D2) x(n -l) + (D3 + D4)xn + (D5 + D6) x(n + l),, _{yQ ( 5 )}

― D1 + D2 + D3 + D4 + D5 + D6 ' If the total length of the electrode 10 on the X axis is X0, then the X-axis coordinate of the touch point is obtained by a proportional algorithm, which is:

X = ^{D2 + D4 + D6} XXO ( 6 X

D1 + D2 + D3 + D4 + D5 + D6 The present invention provides an embodiment of implementing the variable set module 21. As shown in FIG. 5, the clamp circuit 213 includes an operational amplifier OP, which is defined by the clamp circuit 213. The constant potential is controlled by the input voltage Vf at the forward input of the operational amplifier OP. The operational amplifier OP forms a clamp voltage at the inverting input terminal of the operational amplifier OP through a feedback circuit formed by the charge transmitting and receiving capacitor Cc. The charge transceiving detection circuit 211 includes the operational amplifier OP serving as the clamp circuit 213, electrically connected to the charge transceiving capacitor Cc between the inverting input terminal and the output terminal of the operational amplifier OP, and electrically connecting the operational amplifier The AC-DC conversion sub-module 2111 at the output of the OP. The current output terminal of the constant current source 212 and the inverting input terminal of the operational amplifier OP are electrically connected to the first node a. The constant current source 212 can utilize an existing current source product or a circuit that implements a current source function. When a charge flows into or out of the inverting input terminal of the operational amplifier OP, the operational amplifier OP can supply a charge through the charge transmitting and receiving capacitor Cc and quantize it in the form of an output voltage of the operational amplifier OP, the amount of change and the charge of the output voltage The transceiver capacitor Cc is inversely proportional. The output voltage of the operational amplifier OP changes The over-to-DC conversion sub-module 2111 is converted to a digital quantity and output to the data processor for further processing.

The function of the SW circuit is to reset, and it closes once after each detection, and restores the output voltage of the OP to the initial value, and then performs the next detection.

In the above embodiment of the present invention, in order to reset the circuit state after each detection, as shown in Fig. 5, a reset switch SW is electrically connected between both ends of the charge transmitting and receiving capacitor Cc. After each test is completed, the reset switch SW is closed once, and the output voltage of the operational amplifier OP is restored to the initial value, and the next detection is performed.

The rectangular electrode of the present invention can also have a variety of equivalent structures. As shown in Fig. 6, a specific structure of an electrode is such that at least one vertex of the electrode 10 is cut away to form a straight section oblique side 111, so that the electrode 10 is processed into a rectangular electrode 101 having a beveled edge 111. As shown in Fig. 7, another electrode 10 is specifically constructed such that at least one vertex of the electrode 10 is cut away to form a circular arc edge 112, so that the electrode 10 is processed into a rectangular electrode 102 having a circular arc edge 112. As shown in FIG. 8, a specific structure of the electrode 10 is such that at least one side of the electrode 10 is processed with at least two grooves 113, and convex teeth 114 are formed between the two adjacent grooves 113, thereby forming electrodes. 10 is processed into a rectangular electrode 103 with a serrated edge.

The electrode 10 of the present invention is made of indium tin oxide ITO, metal mesh or carbon nanomaterial. As shown in FIG. 9, the electrode 10 is made of a metal mesh, which is formed by lapping the wire 115 into a mesh, and the dotted line in FIG. 9 is a rectangular electrode equivalent to the metal mesh. shape.

Regarding the laying structure of the electrode, the self-capacitance sensing device further includes a substrate made of a resin synthetic film material or glass, and the electrode is attached to the substrate. The electrodes may be attached to the substrate by a bonding, etching, cutting or soldering process.

An electrode scanning detection method that can be used in the present invention is that the self-capacitance change detecting unit includes a set of variable collecting modules. The set of variable set modules is electrically connected to the electrodes in sequence according to the set timing, that is, the electrodes are electrically connected in a time-sharing manner to complete the self-capacitance change detection of each electrode. For example, as shown in FIG. 10, both ends of each electrode 10 shown in FIG. 1 are electrically connected to the n-pair ports of the self-capacitance change detecting unit 2. The self-capacitance change detecting unit 2 is provided with a pair of controlled ports c, d that control the time-sharing electrical connection of each pair of ports. Only one set of the variable set module 21 is provided in the self-capacitance change detecting unit 2. When the detection is started, the controlled ports c and d are electrically connected to a pair of ports whose serial number is 1, and the pair of ports are electrically connected to the first end S1L and the second end S2R of the electrode 10 of the number S1, respectively. The variable collection module 21 electrically connects the first node a and the second node b to the controlled ports c, d in accordance with the method of the present invention, thereby completing the detection of the electrode 10 numbered SI, and the detection structure is The variable set module 21 outputs to the corresponding data processor unit. Thereafter, the controlled ports c and d are electrically connected to the pair of ports of the serial number 2 according to the set timing, and are detected by the electrode 10 of the number S2. Similarly, the controlled port is electrically connected to a pair of ports of sequence number n, and is detected by the electrode 10 numbered Sn, until all the electrodes 10 are detected, and the process of performing an electrode scan is completed. This type of scanning is to use a variable set of modules to detect all electrodes in a time-sharing manner. In another electrode scanning detection mode, the number of the variable collecting modules is less than the number of electrodes; each variable collecting module is controlled to electrically connect one of the electrodes in a one-to-one manner according to a set timing, that is, Each electrode is electrically connected to the time division sub-region to complete the self-capacitance change detection of each electrode. This scheme is similar to the case of the above example. It is only a time-separated region of the electrode scanning method by using multiple sets of variable set modules to perform time-division detection on a region composed of a plurality of electrodes.

It is also possible to use a one-to-one electrode scanning detection method, and the variable collection module electrically connects the electrodes one-to-one. This type of scanning can achieve both time-sharing and time-sharing.

The self-capacitance sensing device can be used to form a separate touch screen as an input device, or can be combined with a display device to form a touch display screen.

When the self-capacitance sensing device is combined with the display device, the self-capacitance sensing device is mounted in the liquid crystal display. As shown in FIG. 11, the liquid crystal display 3 includes a first liquid crystal substrate 31 and a second liquid crystal substrate 32, and a liquid crystal material 33, a pixel electrode 34, and a color sandwiched between the first liquid crystal substrate 31 and the second liquid crystal substrate 32. The filter layer 35 and the black matrix 36. The electrode is attached to an upper layer or a lower layer of the first liquid crystal substrate 31, or an upper layer or a lower layer of the second liquid crystal substrate 32. The electrode may be attached to the first liquid crystal substrate 31 or the second liquid crystal substrate 32 by means of a pasting, etching, cutting or soldering process.

When the self-capacitance sensing device is combined with the display device, a structure in which the inherent circuit of the liquid crystal display is integrated in the same chip can be used in the circuit, and the self-capacitance sensing device is mounted in the liquid crystal display. The liquid crystal display is controlled by a display driving circuit chip. The self-capacitance change detecting unit is integrated in the display driving circuit chip.

When the self-capacitance sensing device is combined with the display device, in order to prevent the electrode scanning detection from interfering with the liquid crystal scanning, the self-capacitance sensing device further includes a coordinated detection module. The self-capacitance sensing device is mounted in a liquid crystal display. The liquid crystal display is controlled by a display driving circuit. At this time, the display driving circuit may be in the same chip as the self-capacitance change detecting unit, or may exist independently of each other in the respective chips. The coordination detection module electrically connects the self-capacitance change detecting unit and the display driving circuit to complete the respective functions of the self-capacitance change detecting unit and the display driving circuit in a time division and/or sub-region without interfering with each other. The completion of the respective functions in the time-division period means that, within a set period of time, the self-capacitance change detecting unit is allocated to one or more time periods to complete the scan detection, in which the display driving circuit does not work, and the remaining time period is allocated to the display. The driving circuit completes the scanning, and the self-capacitance change detecting unit does not work in this stage. The completion of the respective functions of the sub-area means that the screen body is divided into a plurality of non-coincident areas, and the self-capacitance change detecting unit and the display driving circuit are coordinated to perform scanning in different areas, that is, self-capacitance is performed for the same area. When the scan is detected, the display drive scan is not performed, and when the display drive scan is performed, the self-capacitance detection scan is not performed.

Claims

Rights request

A self-capacitance sensing device for a touch screen, comprising at least one electrode, and a self-capacitance change detecting unit electrically connecting the electrodes; wherein:

The electrode is rectangular, and includes a first end and a second end for electrically connecting the self-capacitance change detecting unit along the extending direction of the electrode;

The self-capacitance change detecting unit includes at least one variable collecting module; the variable collecting module includes a constant current source electrically connected to the first node, a clamp circuit and a charge transceiver detecting circuit, and a second node grounded;

In the detecting process for one electrode, the first node of the variable collecting module first electrically connects the first end of the electrode, and the second node electrically connects the second end of the electrode to the first self-capacitance change amount The first node of the variable clamp module is electrically connected to the second end of the electrode, and the second node is electrically connected to the first end of the electrode to collect the second self-capacitance change amount;

The clamping circuit limits a potential of one end of the electrically connected electrode to a constant potential, and the constant current source supplies a constant current to the electrically connected electrode; the charge transceiving detection circuit changes to a self-capacitance of the electrically connected electrode thereof The electrode outputs a charge, and detects the amount of charge output, and quantizes the amount of charge output as a change in self-capacitance.

2. The self-capacitance sensing device for a touch screen according to claim 1, wherein:

The clamping circuit defines a constant potential defined by a potential of one end of the electrically connected electrode as VI, and the constant current supplied from the constant current source to the electrically connected electrode is I, then V1/I = R should be satisfied, and R is a clamp The electrical resistance of the electrode is electrically connected to the circuit and the constant current source.

3. The self-capacitance sensing device for a touch screen according to claim 1, wherein:

The clamp circuit includes an operational amplifier, and a constant potential defined by the clamp circuit is controlled by an input voltage of a forward input terminal of the operational amplifier;

The charge transceiving detection circuit includes the operational amplifier used as a clamp circuit, electrically connected to a charge transceiving capacitor between an inverting input end and an output end of the operational amplifier, and an AC/DC electrically connected to an output end of the operational amplifier Conversion submodule;

The current output terminal of the constant current source and the inverting input terminal of the operational amplifier are electrically connected to the first node.

4. The self-capacitance sensing device for a touch screen according to claim 3, wherein:

A reset switch is further electrically connected between both ends of the charge transceiver capacitor.

5. The self-capacitance sensing device for a touch screen according to claim 1, wherein:

At least one apex angle of the electrode is cut to form a straight line bevel, so that the electrode is machined into a rectangular electrode with a beveled edge.

6. The self-capacitance sensing device for a touch screen according to claim 1, wherein:

At least one vertex of the electrode is cut to form a circular arc segment edge, so that the electrode is processed into a rectangular electrode with a circular arc edge.

7. The self-capacitance sensing device for a touch screen according to claim 1, wherein:

At least one side of the electrode is machined with at least two grooves, and a convex tooth is formed between the two adjacent grooves, so that the electrode is processed into a rectangular electrode with a serrated edge.

8. The self-capacitance sensing device for a touch screen according to claim 1, wherein:

The electrode is made of indium tin oxide, a metal mesh or a carbon nanomaterial.

9. The self-capacitance sensing device for a touch screen according to claim 1, wherein:

Also included is a substrate made of a resin synthetic film material or made of glass to which the electrodes are attached.

10. The self-capacitance sensing device for a touch screen according to claim 1, wherein:

The self-capacitance sensing device is mounted in a liquid crystal display panel; the liquid crystal display panel comprises a first liquid crystal substrate and a second liquid crystal substrate, and a liquid crystal material, a pixel electrode, and a liquid crystal material sandwiched between the first liquid crystal substrate and the second liquid crystal substrate Color filter layer and black matrix;

The electrode is attached to an upper layer or a lower layer of the first liquid crystal substrate or an upper layer or a lower layer of the second liquid crystal substrate.

11. The self-capacitance sensing device for a touch screen according to claim 1, wherein:

The self-capacitance change detecting unit includes a set of variable set modules; the set of variable set modules are controlled to electrically connect the electrodes in sequence according to a set timing, that is, electrically connect the electrodes in a time-sharing manner to complete the electrodes. Self-capacitance change detection.

12. The self-capacitance sensing device for a touch screen according to claim 1, wherein:

The number of the variable collection modules is less than the number of electrodes; each variable collection module is controlled to electrically connect one of the electrodes in a one-to-one manner according to a set timing, that is, electrically connect the electrodes in a time-divisional region. To complete the electricity Extreme self-capacitance change detection. The self-capacitance sensing device for a touch screen according to claim 1, wherein:

The variable collection module electrically connects the electrodes one to one. The self-capacitance sensing device for a touch screen according to claim 1, wherein:

The self-capacitance sensing device is mounted in a liquid crystal display; the liquid crystal display is controlled by a display driving circuit chip; and the self-capacitance change detecting unit is integrated in the display driving circuit chip. The self-capacitance sensing device for a touch screen according to claim 1, wherein:

Also includes a coordinated detection module;

The self-capacitance sensing device is installed in the liquid crystal display; the liquid crystal display is controlled by the display driving circuit; the coordinated detecting module is electrically connected to the self-capacitance change detecting unit and the display driving circuit to make the self-capacitance change detecting unit The respective functions are completed in a time division and/or sub-area without interfering with the display drive circuit. a self-capacitance change detecting method for a touch screen, the self-capacitance sensing device comprising at least one electrode; the electrode comprising a first end and a second end in a first direction; Lie in:

The method performs the following steps for each electrode,

A. electrically connecting a constant current source, a clamp circuit and a charge transceiver detection circuit to the first end of the electrode, grounding the second end of the electrode; the constant current source outputting a current of a constant current value to the electrode; The circuit limits the potential of one end of the electrically connected electrode to a constant potential; the charge transceiving detection circuit is capable of outputting a charge or receiving a charge, and detecting a charge output amount or a receiving amount, and quantizing the charge output amount as a self-capacitance change amount;

If there is no charge output, directly perform step E;

C. electrically connecting a constant current source, a clamp circuit and a charge transceiver detection circuit to the second end of the electrode, and grounding the first end of the electrode;

E. The self-capacitance change detection for the electrode ends. The self-capacitance change detecting method for a touch screen according to claim 16, wherein:

The constant current value outputted by the constant current source to the electrode in step A is I, and the clamp circuit causes one of the electrodes to be electrically connected The constant potential defined by the potential of the terminal is VI, then V1/I = R should be satisfied, and R is the resistance of the electrode electrically connected to the clamp circuit and the constant current source. A touch point coordinate data processing method according to claim 16, wherein the electrodes are sequentially arranged in a second direction perpendicular to the first direction, and are characterized by The methods include:

F. When a touch point changes the self-capacitance of the K electrodes, the amount of change of the self-capacitance of the K pair related to the touch point is obtained, that is, the amount of self-capacitance change of 2K;

G. Select the largest of the 2K self-capacitance changes;

Therefore, the first self-capacitance variation of the electrodes of the T-th electrode along the two sides in the second direction is D ( T +1 ) U, D ( T+2 ) U, . . . , D ( T+W1 ) U, respectively. And D ( T-1 ) U, D ( T-2 ) U, ..., D ( T-W2 ) U; the second self-capacitance change is D ( T +1 ) V, D ( T+2 ) V , .·· , D ( T+W1 ) V, and D ( T-1 ) V, D ( T-2 ) V, ··· , D ( T-W2 ) V, W1+W2+1=K;

H. If the length of each electrode in the first direction is X0 and the length in the second direction is Y0, then the touch point in step A is along the second direction coordinate Y,

t=T+Wl

^tx(DtU + DtV)

Γ- t=T-W2

~ t=T+Wl '

^(DtU + DtV)

t=T-W2

Step A, the touch point along the first direction, the lateral coordinate X is,

t=T+Wl

∑DtV

x= t=T-W2

t=T+Wl

J (DtU + DtV)