CN103092454A - Resistance-type touch screen control circuit and multi-point touch implement method thereof - Google Patents

Abstract

The invention provides a resistance-type touch screen control circuit and a multi-point touch implement method thereof. The resistance-type touch screen control circuit at least comprises a touch screen driving switch module, a touch monitoring module, an analog input signal selecting module, an analog-to-digital converting unit, a digital control logic module, an interior standard module and an oscillator module. Through the touch monitoring module, a touch interrupt signal is generated and whether current touch is single-point touch or multi-point touch is determined, so that the multi-point touch function can be achieved in the current four-wire type resistance touch screen without changing faceplate modules and software and hardware design of the system.

Description

Electric resistance type touch screen control circuit and multipoint touch realization method thereof

Technical field

The present invention relates to a kind of touch screen control circuit and its implementation, particularly relate to a kind of electric resistance type touch screen control circuit and multipoint touch realization method thereof.

Background technology

Touch-screen, as a kind of up-to-date input equipment, is the simplest, convenient, natural at present a kind of man-machine interaction mode.Along with using computer as the growing with each passing day of information source, touch-screen with its be easy to use, sturdy and durable, reaction velocity fast, save the advantages such as space, makes system designers feel more and more to use touch-screen really to have sizable superiority.It has given multimedia with brand-new looks, is extremely attractive brand-new multimedia interactive equipment.According to the principle of work of touch-screen and the medium of transmission information, touch-screen can be divided into following five kinds: resistance-type, condenser type, electromagnetic type, infrared-type and surface acoustic wave type.Wherein resistive touch screen is applied maximum, the widest because know-why is simple, threshold is low, the upstream and downstream integration is complete, manufacture craft is mature and stable, cost is low in various touch-screens.Current resistive touch screen has occupied the principal market of touch-screen, and from various kind touch-screens totally, the market share of resistive touch screen has accounted for 60%.

Resistive touch screen is a kind of sensor, and it is converted to the physical location of touch point (X, Y) in rectangular area the voltage that represents X coordinate and Y coordinate.A lot of LCD modules have all adopted resistive touch screen, and this screen can produce the screen bias voltage with four lines, five lines, six lines, seven lines or eight lines, the voltage of the touch point of simultaneously reading back.Resistive touch screen turns on upper and lower two layers of resistor network by pressure, the position by distribution of resistance with the decision spot pressure.Four lines, five lines, six lines, seven lines, the various combinations of eight line formulas are arranged at present on the market, and all kinds of all have its relative merits, but the most universal with four lines and five lines.

The structural representation that Fig. 1 is a kind of common four-wire type electric resistance touch screen.As shown in Figure 1, the four-wire type resistive touch screen structure is as follows: be coated with the ITO layer of two-layer transparent, homogeneous conductive on glass or acrylic acid substrate, respectively as X electrode and Y electrode, between them by the separately insulation of evenly distributed transparent lattice point.Wherein the ITO of lower floor and glass substrate adhere to, and the ITO on upper strata is attached on the PET film.The positive and negative terminal of X electrode and Y electrode is drawn from two ends respectively by " bus ", and the X electrode is mutually vertical with the position of Y electrodes conduct bar, exit X-, and X+, Y-, Y+ is four lines altogether, the origin of four-wire resistance type touch screen title that Here it is.When the object contact touch screen surface being arranged and impose certain pressure, the generation deformation of ITO conductive layer and the ITO of lower floor on upper strata come in contact, and this structure can be equivalent to the equivalent electrical circuit of Fig. 2.The X of this touch-screen contact, Y coordinate can be divided into following two steps and calculate:

1. calculate the Y coordinate, apply driving voltage Vdrive at the Y+ electrode, the Y-electrode grounding, the X+ electrode measures the voltage of contact point as exit, due to ITO layer homogeneous conductive, contact voltage equals contact Y coordinate and the ratio that shields height with the ratio of driving voltage Vdrive, and y coordinate in contact is:

v wherein _x+for X+ electrode voltage, height _screenfor the touch-screen height;

2. calculate the X coordinate, apply driving voltage Vdrive at the X+ electrode, the X-electrode grounding, the Y+ electrode measures the voltage of contact point as exit, due to ITO layer homogeneous conductive, contact voltage equals contact X coordinate and the ratio that shields width with the ratio of driving voltage Vdrive voltage, and x coordinate in contact is:

v wherein _y+for Y+ electrode voltage, Width _screenfor the touch-screen width.

The voltage recorded is converted into digital signal by analog to digital converter (ADC) usually, then carries out simple process and just can be converted to coordinate, the physical location of judgement contact.It is while on touch-screen, a plurality of target being arranged that there is a problem in above-mentioned resistive touch screen technology, and touch-screen only can be reported a point, lacks the ability of simultaneously following the trail of a plurality of contacts.

Having at present the technology that realizes multiple point touching on the basis of four-wire resistance type touch screen occurs, the Chinese patent that the patent No. of applying for as Biyadi Co Ltd is 200810146683.6 discloses " a kind of recognition methods of touch gestures and device ", it shields control circuit by single-point touches and gathers 5 data, carry out again 2 gesture touch recognition devices, so just need MCU software to carry out gesture identification or special processing unit carries out above-mentioned calculating, the large needs of calculated amount take more resource, have increased and have controlled the difficulty detected.

In sum, calculate and cause calculated amount large and need to take more resource and then increase the problem of controlling the difficulty detected because needing MCU software to carry out gesture identification or special processing unit when the four-wire resistance type touch screen of known prior art is realized multiple point touching, therefore, be necessary to propose improved technological means in fact, solve this problem.

Summary of the invention

For overcoming the above-mentioned shortcoming of prior art, fundamental purpose of the present invention is to provide a kind of electric resistance type touch screen control circuit and multipoint touch realization method thereof, it can realize multi-point touch not changing on existing four-wire resistance type touch screen panel module and system hardware and software design basis, not only reduce taking of calculated amount and resource, and be easy to control detection.

For reaching above-mentioned and other purpose, the invention provides a kind of electric resistance type touch screen control circuit, be applied to a touch-screen system, this touch-screen system at least also comprises a resistive touch screen and a processor, and this electric resistance type touch screen control circuit at least comprises:

Touch-screen driving switch module, be connected with this resistive touch screen, to select different driving switch conductings under the control in the Digital Logic control module, for this resistive touch screen provides driving voltage;

Touch monitoring modular, be connected in this touch-screen driving switch module, for monitoring on this resistive touch screen whether touch is arranged, and produce a touch look-at-me to this processor when having monitored touch, simultaneously, this touch monitoring modular is also for determining that current touch is single-point touches or multiple point touching;

Analog input signal is selected module, is connected in the output terminal that this touch-screen drives the gauge tap module, and it selects the input of corresponding simulating signal as AD conversion unit under the control of this digital control logic module;

AD conversion unit, be connected in this analog input signal and select the module output terminal, for analog input voltage being converted to digital signal and exporting this digital control logic module to;

The digital control logic module, accept the order of this processor to control the duty of these other parts of electric resistance type touch screen control circuit, and this digital signal be sent to this processor to carry out coordinate data calculating by a digital interface module;

The internal reference module, for generation of reference signal, it all is connected with this AD conversion unit, this touch-screen driving switch module and this digital control logic module, with the reference voltage of these AD conversion unit module needs of generation under the control in this digital control logic module and the driving voltage of this resistive touch screen; And

Oscillator module, be used to this electric resistance type touch screen control circuit that clock signal is provided.

Further, this electric resistance type touch screen control circuit also comprises a noise filter module, be connected in this analog input signal select module output terminal with and the AD conversion unit output terminal between, the noise of the digital signal that it is exported for this AD conversion unit of filtering.

Further, this touch monitoring modular can judge that by the variation that detects this resistive touch screen electric current current touch is single-point touches or multiple point touching.

Further, when the size of current of this resistive touch screen of flowing through is constant, be single-point touches; When the size of current of this resistive touch screen of flowing through changes, it is multiple point touching.

For reaching above-mentioned and other purpose, the present invention also provides a kind of implementation method of multi-point touch, is applied to one and at least comprises in the touch-screen system of a resistive touch screen, electric resistance type touch screen control circuit and processor, and this implementation method at least comprises the steps:

Touch and interrupt monitoring, this processor has judged whether to touch look-at-me and has produced;

If there is the look-at-me of touch to produce, this processor sends corresponding work order to digital control logic module and applies driving voltage to control touch-screen driving switch module;

Gather touch point voltage;

Judge that current touch is single-point touches or multiple point touching;

If current touch is single-point touches, the work order that this processor sends the single-point touches mode of operation applies driving voltage to control this touch-screen driving switch module;

Gather touch point voltage, and calculate the coordinate of touch point according to a single-point computation model;

If current touch is multiple point touching, the work order that this processor sends the multiple point touching mode of operation applies driving voltage to control this touch-screen driving switch module;

Gather touch point voltage, and calculate the coordinate at center, touch point and the distance between touch point according to a multiple spot computation model.

Further, this single-point computation model is:

$x=\frac{V_{Y+}}{V_{\mathrm{Drive}}}\×{\mathrm{Width}}_{\mathrm{screen}};$ $y=\frac{V_{X+}}{V_{\mathrm{Drive}}}\×{\mathrm{height}}_{\mathrm{screen}}$

V wherein _x+for the X+ electrode voltage of touch point, height _screenfor touch-screen height, V _y+for Y+ electrode voltage, Width _screenfor the touch-screen width.

Further, before the current touch of judgement is single-point touches or multiple point touching step, also comprise the steps:

$x=\frac{{V^{\′}}_{Y+}}{V_{\mathrm{Drive}}}\×{\mathrm{Width}}_{\mathrm{screen}};$ $y=\frac{{V^{\′}}_{X+}}{V_{\mathrm{Drive}}}\×{\mathrm{height}}_{\mathrm{screen}};$ ${\mathrm{\ΔV}}_{X+}=\frac{R_{\mathrm{dis}\tan \mathrm{ce}}/2}{R_{\mathrm{ALL}}}\×V_{\mathrm{Drive}};$

Wherein, (x, y) represents the coordinate at center, touch point, V ' _x+be the X+ electrode voltage at two centers, touch point, height _screenfor touch-screen height, V ' _y+be the Y+ electrode voltage at two centers, touch point, Width _screenfor the touch-screen width, Δ V _x+be twice voltage difference, R _{dis tan ce}be the resistance between two touch points, R _aLLall resistance for Y-direction.

Further, this multiple spot computation model is: judge whether this touch look-at-me becomes height, interrupt detecting for height continues to touch; Otherwise, judge that current touch is single-point touches or multiple point touching.

Further, after the distance between the coordinate that calculates the coordinate of touch point/calculate center, touch point and touch point, also comprise the steps: to judge whether this touch look-at-me becomes height, for height finishes this workflow; Otherwise continuing the current touch of judgement is single-point touches or multiple point touching.

Further, judgement single-point touches or multiple point touching can obtain by the flow through variation of this resistive touch screen electric current of detection.

Compared with prior art, a kind of electric resistance type touch screen control circuit of the present invention and multiple point touching implementation method thereof touch the difference (single-point touches or multiple point touching) of interrupting by touching monitoring module monitors, realized can realizing the purpose of multi-point touch on existing four-wire type electric resistance touch screen, for capacitive touch screen, it can significantly reduce costs (cost only for capacitance touch screen 1/10th), simplicity of design, peripheral circuit is basic Resistor-Capacitor Unit; Design cycle is short, has greatly accelerated the cycle that product is successfully introduced to the market.

The accompanying drawing explanation

The structural representation that Fig. 1 is common four-wire type electric resistance touch screen;

The equivalent circuit diagram that Fig. 2 is Fig. 1;

The equivalent circuit diagram that Fig. 3 is four-wire resistance type touch screen single-point touches and 2 touches;

The system architecture diagram of the touch-screen system that Fig. 4 is a kind of electric resistance type touch screen control circuit application of the present invention;

The system architecture diagram of the preferred embodiment of the electric resistance type touch screen control circuit that Fig. 5 is the present invention;

The multipoint touch realization method process flow diagram of the electric resistance type touch screen control circuit that Fig. 6 is the present invention.

Embodiment

Below, by specific instantiation accompanying drawings embodiments of the present invention, those skilled in the art can understand other advantage of the present invention and effect easily by content disclosed in the present specification.The present invention also can be different by other instantiation implemented or applied, the every details in this instructions also can be based on different viewpoints and application, carries out various modifications and change not deviating under spirit of the present invention.

Before explanation preferred embodiment of the present invention, first by 2, touch the principle of work that detects the multi-point touch that the present invention is described: the equivalent circuit diagram that Fig. 3 is four-wire resistance type touch screen single-point touches and 2 touches, from background technology, on the four-wire type touch-screen, only have while a bit touching, X+, the conducting of X-driving switch, directions X applies driving voltage V _drive, read the voltage V of the directions X of touch point from Y+ _x+otherwise, Y+ and the conducting of Y-driving switch, Y-direction applies driving voltage V _drive, read the voltage V of touch point Y-direction from X+ _y+.

Therefore, the voltage that directions X is read during single-point touches is:

$V_{X+}=\frac{R_{\mathrm{bottom}}}{R_{\mathrm{top}}+R_{\mathrm{bottom}}}\×V_{\mathrm{Drive}}=\frac{R_{\mathrm{bottom}}}{R_{\mathrm{ALL}}}\×V_{\mathrm{Drive}}$

And 2 while touching, now exist two contact points all with the X+ conducting, therefore:

$V_{X+}^{\′}\≈\frac{R_{\mathrm{bottom}}^{\′}+R_{\mathrm{dis}\tan \mathrm{ce}}/2}{R_{\mathrm{top}}^{\′}+R_{\mathrm{dis}\tan \mathrm{ce}}+R_{\mathrm{bottom}}^{\′}}\×V_{\mathrm{Drive}}=\frac{R_{\mathrm{bottom}}^{\′}+R_{\mathrm{dis}\tan \mathrm{ce}}/2}{R_{\mathrm{ALL}}}\×V_{\mathrm{Drive}}$

Can find out, due to the resistance R of Y+ to Y- _aLLfor constant, V _drivebe also constant, so the actual coordinate that is approximately center, two touch points of voltage read of X+, and the difference of twice voltage

therefore be directly proportional to the distance between two touch points, when touching, be output as the coordinate at center, two touch points and the distance between two touch points at 2.

The system architecture diagram of the touch-screen system that Fig. 4 is applied by a kind of electric resistance type touch screen control circuit of the present invention.As shown in Figure 4, this touch-screen system comprises: resistive touch screen 401, touch screen control circuit 402 and processor 403.

Resistive touch screen 401 is as the analog input part, and it is connected in touch screen control circuit 402; Touch screen control circuit 402 obtains the simulating signal of resistive touch screen 401 for the current touch condition according to detecting acquisition, and is that digital signal exports processor 403 to by analog signal conversion; 403 of processors obtain the coordinate data of touch point by corresponding computation model according to the work at present pattern.At this, 402 of touch screen control circuits are core.

The system architecture diagram of the preferred embodiment of the electric resistance type touch screen control circuit that Fig. 5 is the present invention.As shown in Figure 5, a kind of electric resistance type touch screen control circuit of the present invention comprises touch-screen driving switch module 501, touch monitoring modular 502, analog input signal selection module 503, AD conversion unit 504, digital control logic module 505, digital interface module 506, internal reference module 507 and oscillator module 508.

Touch-screen driving switch module 501 is connected with resistive touch screen 401, be mainly resistive touch screen 401 the driving signal is provided, that is, select different driving switch conductings under the control of Digital Logic control module 505, think that outside four-wire type touch-screen provides driving voltage V _dRIVE, such as, under different mode of operations, as under single-point pattern, two point pattern, different driving switchs are by conducting, and in preferred embodiment of the present invention, resistive touch screen 401 is four-wire resistance type touch screen, touch monitoring modular 502 and be connected in touch-screen driving switch module 501, whether it has touch for monitoring on current resistive touch screen, if touch is arranged, the touch signal of simulation is transferred into and touches monitoring modular 502, touch 502 of monitoring modulars and can produce a touch look-at-me (TOUCH) to processor 403, here processor 403 can be for example MCU, simultaneously, touch monitoring modular 502 also for determining that current touch is single-point touches or multiple point touching, specifically, in preferred embodiment of the present invention, take and determine single-point touches or 2 touches are example, driving voltage in the single-point touches situation on whole touch-screen is constant, single-point touches can't change the size of resistance, therefore size of current is constant, and under 2 touches, because two touch points wherein can short circuit part resistance, the size of current of touch-screen of flowing through can change, that is to say, can judge that by the variation that detects electric current current touch is single-point touches or 2 touches, analog input signal is selected module 503, be connected in touch-screen and drive gauge tap 501 output terminals, it selects the input of corresponding simulating signal as AD conversion unit 504 under the control of digital control logic module 505, for example, when the X+/X-direction applies driving voltage, read the voltage signal of Y+ exit, AD conversion unit 504 is connected in the output terminal that analog input signal is selected module 503, for analog input voltage (simulating signal of input) is converted to digital signal and exports digital control logic module 505 to, digital control logic module 505, accept the order of ppu 403 to control the duty of touch screen control circuit each several part, and digital signal be sent to ppu 403 to carry out coordinate data calculating by digital interface module 506, digital interface module 506, for connecting ppu 403 and digital control logic module 505, between transmits mode of operation control signal and coordinate data, internal reference module 507, for generation of reference signal, it is connected with AD conversion unit 504, touch-screen driving switch 501 and digital control logic module 505, the reference voltage VREF that generation AD conversion unit 504 modules need under the control of digital control logic module 505 and the driving voltage V of touch-screen _dRIVE, at this, internal reference module 507 both can have been used the inner reference voltage produced also can external accurate reference voltage, oscillator module 508, be used to whole touch screen control circuit that clock signal is provided.

In addition, for realizing better the present invention, a kind of electric resistance type touch screen control circuit of the present invention also comprises a noise filter module, it is connected in analog input signal and selects module 503 output terminals and AD conversion unit 504, the noise of the digital signal of exporting for filtering AD conversion unit 504, reduce the impact of outside noise on measuring accuracy.

At this, it should be noted that, ppu 403 can be various subsystems, mobile phone for example, the hardware system of panel computer, media player, GPS navigation instrument etc., touch the difference (single-point touches or 2 touches) of interrupting according to touch-screen, choose the mode of operation of touch screen control circuit, obtain the touch point coordinate information, it can identify all multiple spot inputs, by special algorithm, can carry out action recognition according to coordinate (can identify amplification, dwindle, drag, slide, anticlockwise, right rotation), report the multiple spot coordinate position simultaneously.

The multipoint touch realization method process flow diagram of the touch-screen system that Fig. 6 is the present invention.As shown in Figure 6, the multipoint touch realization method of the present invention's resistive touch screen system comprises the steps:

Step 601: touch and interrupt detecting, whether processor 403 judgement touch monitoring modulars 502 produce and touch look-at-me TOUCH;

Step 602: do not produce look-at-me if touch monitoring modular 502, continue to touch and interrupt detecting; Otherwise, meaning that current touch-screen has touch, processor 403 sends corresponding work order to digital control logic module 505 by digital interface module 506 and applies driving voltage to control touch-screen driving switch module 501;

Step 603: gather touch point voltage, and enter step 604;

Step 604, judgement touches look-at-me TOUCH and whether becomes height, for height returns to step 501 continuation touch, interrupts detecting; Otherwise, judge that current touch is single-point touches or multiple point touching, specifically, judgement single-point touches or multiple point touching can obtain by the variation that detects electric current, in general, driving voltage in the single-point touches situation on whole touch-screen is constant, single-point touches can't change the size of resistance, so size of current is constant, and under 2 or multiple point touching, due to two or more touch points meeting short circuit part resistance, the size of current of the touch-screen of flowing through can change;

Step 605, if it is single-point touches that processor 403 is judged current touch, processor 403 applies driving voltage by work order to the digital control logic module 505 of digital interface module 506 transmission single-point touches mode of operations to control touch-screen driving switch module 501, and enters step 506;

Step 606, gather touch point voltage, calculates the coordinate of touch point by processor 403 according to a single-point computation model, and enter step 509, and specifically, this single-point computation model is:

$x=\frac{V_{Y+}}{V_{\mathrm{Drive}}}\×{\mathrm{Width}}_{\mathrm{screen}};$ $y=\frac{V_{X+}}{V_{\mathrm{Drive}}}\×{\mathrm{height}}_{\mathrm{screen}}$

V wherein _x+for the X+ electrode voltage of touch point, height _screenfor touch-screen height, V _y+for Y+ electrode voltage, Width _screenfor the touch-screen width;

Step 607, if it is multiple point touching that processor 403 is judged current touch, processor 403 applies driving voltage by work order to the digital control logic module 505 of digital interface module 506 transmission multiple point touching mode of operations to control touch-screen driving switch module 501, and enters step 508;

Step 608, gather touch point voltage, calculates the coordinate at center, touch point and the distance between touch point by processor 403 according to a multiple spot computation model, and enter step 609, and 2 touches of take here are example, and this multiple spot computation model is:

$x=\frac{{V^{\′}}_{Y+}}{V_{\mathrm{Drive}}}\×{\mathrm{Width}}_{\mathrm{screen}};$ $y=\frac{{V^{\′}}_{X+}}{V_{\mathrm{Drive}}}\×{\mathrm{height}}_{\mathrm{screen}};$ ${\mathrm{\ΔV}}_{X+}=\frac{R_{\mathrm{dis}\tan \mathrm{ce}}/2}{R_{\mathrm{ALL}}}\×V_{\mathrm{Drive}};$

Wherein, (x, y) represents the coordinate at center, touch point, V ' _x+be the X+ electrode voltage at two centers, touch point, height _screenfor touch-screen height, V ' _y+be the Y+ electrode voltage at two centers, touch point, Width _screenfor the touch-screen width, Δ V _x+be twice voltage difference, R _{dis tan ce}be the resistance between two touch points, R _aLLall resistance for Y-direction;

Step 609, judgement touches look-at-me TOUCH and whether becomes height, if do not become height, enters step 604 and proceeds the multiple point touching judgement, becomes height if touch look-at-me TOUCH, process ends.

Visible, the invention provides the implementation method of a kind of resistive touch screen system, touch screen control circuit and multiple point touching thereof, can realize multi-point touch on existing four-wire type electric resistance touch screen, for capacitive touch screen, it can significantly reduce costs (cost only for capacitance touch screen 1/10th), simplicity of design, peripheral circuit is basic Resistor-Capacitor Unit; Design cycle is short, has greatly accelerated the cycle that product is successfully introduced to the market.

The present invention is a kind of electric resistance type touch screen control circuit of supporting 2 touches, can be directly compatible single-point resistive touch screen at present, terminal system only need import this controller, in panel module and system hardware and software design, does not need to change fully, system applies can be upgraded, become two point by single-point, the use-pattern of this touch screen control circuit and application circuit, identical with the traditional electrical resistive, and be that hardware realizes that touch detection at 2, the non-MCU software simulation of its effect can be compared.

Claims (10)

1. an electric resistance type touch screen control circuit, be applied to a touch-screen system, and this touch-screen system at least also comprises a resistive touch screen and a processor, and this electric resistance type touch screen control circuit at least comprises:

Touch-screen driving switch module, be connected with this resistive touch screen, to select different driving switch conductings under the control in the Digital Logic control module, for this resistive touch screen provides driving voltage;

Touch monitoring modular, be connected in this touch-screen driving switch module, for monitoring on this resistive touch screen whether touch is arranged, and produce a touch look-at-me to this processor when having monitored touch, simultaneously, this touch monitoring modular is also for determining that current touch is single-point touches or multiple point touching;

Analog input signal is selected module, is connected in the output terminal that this touch-screen drives the gauge tap module, and it selects the input of corresponding simulating signal as AD conversion unit under the control of this digital control logic module;

AD conversion unit, be connected in this analog input signal and select the module output terminal, for analog input voltage being converted to digital signal and exporting this digital control logic module to;

The digital control logic module, accept the order of this processor to control the duty of these other parts of electric resistance type touch screen control circuit, and this digital signal be sent to this processor to carry out coordinate data calculating by a digital interface module;

The internal reference module, for generation of reference signal, it all is connected with this AD conversion unit, this touch-screen driving switch module and this digital control logic module, with the reference voltage of these AD conversion unit module needs of generation under the control in this digital control logic module and the driving voltage of this resistive touch screen; And

Oscillator module, be used to this electric resistance type touch screen control circuit that clock signal is provided.

2. electric resistance type touch screen control circuit as claimed in claim 1, it is characterized in that: this electric resistance type touch screen control circuit also comprises a noise filter module, be connected in this analog input signal select module output terminal with and the AD conversion unit output terminal between, the noise of the digital signal that it is exported for this AD conversion unit of filtering.

3. electric resistance type touch screen control circuit as claimed in claim 1, it is characterized in that: this touch monitoring modular can judge that by the variation that detects this resistive touch screen electric current current touch is single-point touches or multiple point touching.

4. electric resistance type touch screen control circuit as claimed in claim 3, is characterized in that: when the size of current of this resistive touch screen of flowing through is constant, be single-point touches; When the size of current of this resistive touch screen of flowing through changes, it is multiple point touching.

5. the implementation method of a multi-point touch, be applied to one and at least comprise in the touch-screen system of a resistive touch screen, electric resistance type touch screen control circuit and processor, and this implementation method at least comprises the steps:

Touch and interrupt monitoring, this processor has judged whether to touch look-at-me and has produced;

If there is the look-at-me of touch to produce, this processor sends corresponding work order to digital control logic module and applies driving voltage to control touch-screen driving switch module;

Gather touch point voltage;

Judge that current touch is single-point touches or multiple point touching;

If current touch is single-point touches, the work order that this processor sends the single-point touches mode of operation applies driving voltage to control this touch-screen driving switch module;

Gather touch point voltage, and calculate the coordinate of touch point according to a single-point computation model;

If current touch is multiple point touching, the work order that this processor sends the multiple point touching mode of operation applies driving voltage to control this touch-screen driving switch module;

Gather touch point voltage, and calculate the coordinate at center, touch point and the distance between touch point according to a multiple spot computation model.

6. the implementation method of multi-point touch as claimed in claim 5, it is characterized in that: this single-point computation model is:

$x=\frac{V_{Y+}}{V_{\mathrm{Drive}}}\×{\mathrm{Width}}_{\mathrm{screen}};$ $y=\frac{V_{X+}}{V_{\mathrm{Drive}}}\×{\mathrm{height}}_{\mathrm{screen}}$

V wherein _x+for the X+ electrode voltage of touch point, height _screenfor touch-screen height, V _y+for Y+ electrode voltage, Width _screenfor the touch-screen width.

7. the implementation method of multi-point touch as claimed in claim 5, is characterized in that: before the current touch of judgement is single-point touches or multiple point touching step, also comprise the steps:

$x=\frac{{V^{\′}}_{Y+}}{V_{\mathrm{Drive}}}\×{\mathrm{Width}}_{\mathrm{screen}};$ $y=\frac{{V^{\′}}_{X+}}{V_{\mathrm{Drive}}}\×{\mathrm{height}}_{\mathrm{screen}};$ ${\mathrm{\ΔV}}_{X+}=\frac{R_{\mathrm{dis}\tan \mathrm{ce}}/2}{R_{\mathrm{ALL}}}\×V_{\mathrm{Drive}};$

Wherein, (x, y) represents the coordinate at center, touch point, V ' _x+be the X+ electrode voltage at two centers, touch point, height _screenfor touch-screen height, V ' _y+be the Y+ electrode voltage at two centers, touch point, Width _screenfor the touch-screen width, Δ V _x+be twice voltage difference, R _{dis tan ce}be the resistance between two touch points, R _aLLall resistance for Y-direction.

8. the implementation method of multi-point touch as claimed in claim 5, it is characterized in that: this multiple spot computation model is: judge whether this touch look-at-me becomes height, interrupt detecting for height continues to touch; Otherwise, judge that current touch is single-point touches or multiple point touching.

9. the implementation method of multi-point touch as claimed in claim 5, it is characterized in that: after the distance between the coordinate that calculates the coordinate of touch point/calculate center, touch point and touch point, also comprise the steps: to judge whether this touch look-at-me becomes height, for height finishes this workflow; Otherwise continuing the current touch of judgement is single-point touches or multiple point touching.

10. the implementation method of multi-point touch as claimed in claim 5 is characterized in that: judgement single-point touches or multiple point touching can obtain by the flow through variation of this resistive touch screen electric current of detection.

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