CN102339190A - Method for recognizing two-point touch of resistance touch screen on mobile phone - Google Patents

Abstract

The invention discloses a method for recognizing two-point touch of a resistance touch screen on a mobile phone. By the method, four general purpose input/output (GPIO) interfaces on a processor of the mobile phone can be used for realizing reference voltage and ground input and can be scanned at the same time, and four analog-to-digital converters (ADCs) can be used for inspecting voltage without the increase of cost; and a common resistance touch screen (four wires) with low cost has a two-point touch recognition function. Compared with a multipoint capacitance touch screen, the resistance touch screen has greatly-reduced cost, can have functions of zooming, dragging, rotation and the like of photographs and maps and can provide a low-cost lower-accuracy multipoint experience for a user. The method is easy to realize, makes the cost not increased, is convenient to use, is high in user experience and can be extremely conveniently used by the user.

Description

A kind of method that on mobile phone, realizes 2 touch recognition of electric resistance touch screen

Technical field

This practicality invention relates to electronic device field, relates in particular to a kind of method that on mobile phone, realizes 2 touch recognition of electric resistance touch screen.

Background technology

Touch-screen is as a kind of up-to-date input equipment, and it is the simplest, convenient, natural at present a kind of man-machine interaction mode.It has given multimedia with brand-new looks, is extremely attractive brand-new multimedia interactive equipment.Distinguish touch-screen from know-why, can be divided into five basic kind: vector pressure sensing technology touch-screen, resistive technologies touch-screen, capacitance technology touch-screen, infrared technology touch-screen, surface acoustic wave technique touch-screen.Main resistance-type and the capacitive touch screen of using on mobile phone.

The major part of electric resistance touch screen is a resistance film screen that cooperates very much with display surface; This is a kind of laminated film of multilayer; It with one deck glass or duroplasts flat board as basic unit; The surface scribbles layer of transparent oxidized metal (transparent conductive resistance; General ITO, the indium oxide of adopting) conductive layer is stamped one deck outside surface cure process, smooth anti-friction plastic layer, its inside surface above again and also scribbles one deck coating, between them, has the transparent isolating points of many tiny (less than 1/1000 inches) to separate insulation to two conductive layers.When the finger touch screen, two conductive layers has just had contact in the position, touch point, and resistance changes, and detects different voltages on X and the Y both direction, just can calculate that (X, position Y) is with reference to figure 1.

The capacitance technology touch-screen is to utilize the induction by current of human body to carry out work.It is four layers of compound glass screen; The inside surface of glass screen and interlayer respectively scribble one deck ITO (indium oxide), and outermost layer is a skim silicon soil glassivation, and interlayer ITO coating is as workplace; Draw four electrodes on four angles, internal layer ITO is that screen layer is to guarantee good working environment.When finger touch was on metal level, because people's bulk electric field, user and touch screen surface formed with a coupling capacitance, and for high-frequency current, electric capacity is direct conductor, so finger siphons away a very little electric current from contact point.This electric current divides the electrode on four jiaos from touch-screen and flows out, and the electric current of these four electrodes of flowing through is directly proportional with the distance of pointing four jiaos, and controller passes through the accurate Calculation to these four current ratios, draws touch point position.

Electric resistance touch screen is owing to dependable performance, and precision is high, and cost is low, has a wide range of applications in field of mobile phones at present.Capacitance touch screen has improved the experience of man-machine interaction greatly owing to support multiple point touching in the mobile phones design of a new generation, obtain user's approval, but cost is high, and it is low to produce yield, has hindered the application of capacitance touch screen greatly.Present multiple point touching implementation mainly contains:

1. the hardware using capacitance plate is realized multiple point touching through software.Advantage is highly sensitive, stable performance, and counting of support can be satisfied absolute major applications demand; Shortcoming is that cost is high, complex manufacturing, and also there is patent protection in Apple.

2. hardware using numeral resistance screen is actually with the material of resistance screen and makes a transparent keyboard matrix, judges the point of being pressed through rank scanning.Advantage is that price comparison is cheap, dependable performance, supported counting at most; Deficiency is to need many ranks line interfaces, can not realize handwriting functions, in multiple spot identification, has the blind area.

3. hardware using artifical resistance screen goes out multiple point touching through computed in software in special chip.Advantage is to support multiple point touching, keeps handwriting functions again, does not increase cost; Shortcoming is that counting of support is minimum, and performance and stability wait checking.

The present invention adopts cheaply on the four-wire ohm touch-screen, do not increase hardware cost, realizes 2 touch recognition.

Summary of the invention

To the deficiency of prior art, the object of the invention is to provide a kind of method that on mobile phone, realizes 2 touch recognition of electric resistance touch screen.

Of Fig. 5 is 2 of the touch-screens equivalent operating circuit model when touching, X ₊, X _-And Y ₊, Y _-Two conduction workplaces of expression touch-screen, R _X1, R _X2, R _X3And R _Y1, R _Y2, R _Y3The grading resistance that produces on X, the Y workplace when expression touches respectively.K1, K2 represent to press the position of touch-screen.R _Z1, R _Z2Resistance when representing 2 contacts.The method that realizes 2 touch recognition is following:

Press first contact, produces to interrupt, and begins to calculate first point coordinate.

GPIO1 exports high level, the GPIO2 output low level, and measuring voltage calculates first X1 coordinate.

GPIO3 exports high level, the GPIO4 output low level, and measuring voltage calculates first Y1 coordinate.

Press second contact, begins to calculate second point coordinate.

GPIO1 exports high level, the GPIO2 output low level, and measuring voltage calculates second X2 coordinate.

GPIO3 exports high level, the GPIO4 output low level, and measuring voltage calculates second Y2 coordinate.

The present invention utilizes 4 GPIO mouths (the general input and output of General PurposeInput/Output on the handset processes device; Be called for short the IO mouth) realization reference voltage and ground input; Can scan simultaneously, use 4 ADC (Analog-to-Digital Converter analog to digital converter) to carry out the detection of voltage.

Description of drawings

Fig. 1 is an electric resistance touch screen principle schematic of the present invention;

Fig. 2 is an electric resistance touch screen single-point identification synoptic diagram of the present invention;

Fig. 3 is another embodiment synoptic diagram of electric resistance touch screen single-point identification of the present invention;

Fig. 4 is a bow and beam bearings synoptic diagram of the present invention;

Fig. 5 is 2 identification of electric resistance touch screen of the present invention synoptic diagram.

Embodiment

Like Fig. 2, shown in Figure 3, the equivalent-circuit model of touch-screen work, X ₊, X _-And Y ₊, Y _-Two conduction workplaces of expression touch-screen, R _X1, R _X2And R _Y1, R _Y2The grading resistance that produces on X, the Y workplace when expression touches respectively.Fig. 2 is at X ₊, X _-On add reference voltage, on ADC3, measure dividing potential drop, Fig. 3 is at Y ₊, Y _-On add reference voltage, on ADC1, measure dividing potential drop.More than two steps form a measuring period, can calculate one group of X, Y coordinate.ADC1～4 measured voltage are V1～V4, and the width of touch-screen and length are respectively W and L, use the X that value method calculates, the coordinate figure of Y to be so:

$X=\frac{V3-V2}{V1-V2}\×L$

$Y=\frac{V1-V4}{V3-V4}\×W$

If the employing bow and beam bearings improves measuring accuracy, and is as shown in Figure 4, ABCD is the coordinate points on four summits of the corresponding LCD of touch-screen, and this 4 point of striking obtains four groups of coordinate figures: (X respectively _a, Y _a), (X _b, Y _b), (X _c, Y _c), (X _d, Y _d).Calculate touch screen center point coordinate (X ₀, Y ₀) do

$X_0=\frac{X_a+X_b+X_c+X_d}{4}$

$Y_0=\frac{Y_a+Y_b+Y_c+Y_d}{4}$

If Δ X=X _b-X _a+ X _d-X _c, Δ Y=Y _b-Y _a+ Y _d-Y _c, finally can get contact coordinate:

$X=\frac{V3-V2-X_0}{\mathrm{\ΔX}}\×L+\frac{L}{2}$

$Y=\frac{V1-V4-X_0}{\mathrm{\ΔY}}\×W+\frac{W}{2}$

Adopt bow and beam bearings, resulting contact coordinate is more accurate.

When 2 of touch-screens touch, as shown in Figure 5, the equivalent-circuit model when 2 of touch-screens touch, X ₊, X _-And Y ₊, Y _-2 conduction workplaces of expression touch-screen, R _X1, R _X2, R _X3And R _Y1, R _Y2, R _Y3The grading resistance that produces on X, the Y workplace when expression touches respectively.K1, K2 represent to press the position of touch-screen.R _Z1, R _Z2Resistance when representing 2 contacts.

Suppose GPIO1 output high level, the GPIO2 output low level, ADC1 when single-point is pressed～4 measured voltage are V1_1～V4_1, ADC1 when pressing for 2～4 measured voltage are V1_2～V4_2.Relation below above voltage satisfies:

$V3\_1=V4\_1=\frac{(V1\_1-V2\_1)\×(R_{x1}+R_{x2})}{R_{x1}+R_{x2}+R_{x3}};$

V1_1-V2_1≥V1_2-V2_2

Introduce three new argument L1, L2, L3 now, represent the touch-screen width with the label equivalent resistance respectively, it is wide that three's summation equals touch-screen.Also introducing a restrictive condition according to reality in addition, when being pressed, as long as the program detection speed is enough fast, for program, just do not have situation about pressing simultaneously at 2, all is to press successively or unclamp all the time.

There is not any problem for the single-point position Detection; We handle 2 situation now, and in conjunction with the restrictive condition that introduce the front, in the middle of program can detect being arranged a bit of time is that single-point is pressed; Just program detects K1 earlier and presses, and just detects K2 through a bit of time and presses.This pilot process can accurately obtain the K1 position, if the proportionate relationship that we change before and after utilizing just can calculate the position that back K2 presses.

K1 presses separately:

L＝L1+L2+L3

$L1=\frac{V1\_1-V3\_1}{V1\_1-V2\_1}\×(L1+L2+L3)$

K1 and K2 press simultaneously and (ignore R _Z1, R _Z2Influence):

$\frac{V1\_2-V3\_2}{L1}=\frac{V4\_2-V2\_2}{L3}$

Because L1+L2+L3 is the width L of known conditions touch-screen, so have:

$L3=\frac{V4\_2-V2\_2}{V1\_2-V3\_1}\×L1;$

$L3=\frac{V4\_2-V2\_2}{V1\_2-V3\_2}\×\frac{V1\_1-V3\_1}{V1\_1-V2\_1}\×L$

X＝L-L3

To here we obtained by 2 particular location, as long as we handle respectively X and the Y axle of touch-screen according to the method, just can be on conventional, electric-resistance be shielded the detection of 2 touch locations of realization.

Performing step is following:

Press first contact, produces to interrupt, and begins to calculate first point coordinate.

GPIO1 exports high level, the GPIO2 output low level, and measuring voltage calculates first X1 coordinate.

GPIO3 exports high level, the GPIO4 output low level, and measuring voltage calculates first Y1 coordinate.

Press second contact, begins to calculate second point coordinate.

GPIO1 exports high level, the GPIO2 output low level, and measuring voltage calculates second X2 coordinate.

GPIO3 exports high level, the GPIO4 output low level, and measuring voltage calculates second Y2 coordinate.

Claims (3)

1. method that on mobile phone, realizes 2 touch recognition of electric resistance touch screen, the equivalent operating circuit model when 2 of touch-screens touch, X ₊, X _-And Y ₊, Y _-Two conduction workplaces of expression touch-screen, R _X1, R _X2, R _X3And R _Y1, R _Y2, R _Y3The grading resistance that produces on X, the Y workplace when expression touches respectively, K1, K2 represent to press the position of touch-screen, R _Z1, R _Z2Resistance when representing 2 contacts, it is characterized in that: the method for 2 touch recognition of described realization is following:

Press first contact, produces to interrupt, and begins to calculate first point coordinate;

GPIO1 exports high level, the GPIO2 output low level, and measuring voltage calculates first X1 coordinate;

GPIO3 exports high level, the GPIO4 output low level, and measuring voltage calculates first Y1 coordinate;

Press second contact, begins to calculate second point coordinate;

GPIO1 exports high level, the GPIO2 output low level, and measuring voltage calculates second X2 coordinate;

GPIO3 exports high level, the GPIO4 output low level, and measuring voltage calculates second Y2 coordinate.

2. a kind of method that on mobile phone, realizes 2 touch recognition of electric resistance touch screen according to claim 1 is characterized in that: described 4 ADC analog to digital converters that utilize on the handset processes device, ADC also can be used as general input and output simultaneously.

3. a kind of method that on mobile phone, realizes 2 touch recognition of electric resistance touch screen according to claim 1; It is characterized in that: 4 GPIO effected of described use reference voltage and ground input; Can scan simultaneously, use 4 ADC to carry out the inspection of voltage.

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