CN102339190B - 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 realizes 2 touch recognition of electric resistance touch screen on mobile phone

Technical field

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

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.From know-why, distinguish touch-screen, 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 coordinated very much with display surface, this is a kind of laminated film of multilayer, it usings one deck glass or duroplasts flat board as basic unit, surface scribbles layer of transparent oxidized metal (transparent conductive resistance, the general ITO that adopts, indium oxide) conductive layer, the above is stamped one deck outside surface cure process, smooth anti-friction plastic layer, its inside surface again and also scribbles one deck coating, between them, has the transparent isolating points of many tiny (being less than 1/1000 inch) that two conductive layers is separated to insulation.When the finger touch screen, two conductive layers has just had contact in the position, touch point, and resistance changes, and detects different voltage on X and Y both direction, just can calculate the position of (X, Y), with reference to figure 1.

The capacitance technology touch-screen is to utilize the electric current induction 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 skim silicon soil glassivation, and interlayer ITO coating is as workplace; on four angles, draw four electrodes, internal layer ITO is that screen layer is to guarantee good working environment.When finger touch was on metal level, due to 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 to the distance of finger to four jiaos, and controller, by the accurate Calculation to these four current ratios, draws the position of touch point.

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

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

2. hardware using numeral touch screens, be actually with the material of touch screens and make a transparent keyboard matrix, by rank scanning, judges the point of pressing.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, has blind area in multiple spot identification.

3. hardware using artifical resistance screen, calculate multiple point touching by software in special chip.Advantage is to support multiple point touching, keeps again handwriting functions, 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 the touch recognition of 2.

Summary of the invention

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

Equivalent operating circuit model while being as described in Figure 52 touches of touch-screen, X ₊, X _-And Y ₊, Y _-Two conduction workplaces that mean touch-screen, R _X1, R _X2, R _X3And R _Y1, R _Y2, R _Y3The grading resistance produced on X, Y workplace while meaning to touch respectively.K1, K2 mean to press the position of touch-screen.R _Z1, R _Z2Resistance while meaning 2 contacts.The method that realizes 2 touch recognition is as follows:

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

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

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

Press the second contact, starts to calculate the second point coordinate.

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

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

The present invention utilizes 4 GPIO mouths (the General PurposeInput/Output universal input output on the handset processes device, abbreviation IO mouth) realize 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.

The accompanying drawing explanation

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

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

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

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

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

Embodiment

As shown in Figure 2 and Figure 3, the equivalent-circuit model of touch-screen work, X ₊, X _-And Y ₊, Y _-Two conduction workplaces that mean touch-screen, R _X1, R _X2And R _Y1, R _Y2The grading resistance produced on X, Y workplace while meaning to touch 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.Above two steps form a measuring period, can calculate one group of X, Y coordinate.The voltage that ADC1～4 measures is V1～V4, and the width of touch-screen and length are respectively W and L, and the coordinate figure of X, the Y calculated by value method so is:

$X=\frac{V3-V2}{V1-V2}\×L$

$Y=\frac{V1-V4}{V3-V4}\×W$

If the employing bow and beam bearings, improve measuring accuracy, as shown in Figure 4, ABCD is the coordinate points on tetra-summits of the corresponding LCD of touch-screen, and this 4 point of striking, obtain 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) be

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

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

If Δ X=X _b-X _a+ X _d-X _c, Δ Y=Y _b-Y _a+ Y _d-Y _c, finally can obtain 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 that mean touch-screen, R _X1, R _X2, R _X3And R _Y1, R _Y2, R _Y3The grading resistance produced on X, Y workplace while meaning to touch respectively.K1, K2 mean to press the position of touch-screen.R _Z1, R _Z2Resistance while meaning 2 contacts.

Suppose GPIO1 output high level, the GPIO2 output low level, the voltage that ADC1 when single-point is pressed～4 are measured is V1_1～V4_1, the voltage that ADC1 when pressing for 2～4 are measured is V1_2～V4_2.Above voltage meets following relation:

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

V1_1-V2_1≥V1_2-V2_2

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

There is not any problem in detection for the single-point position, we process the situation of 2 now, and in conjunction with the restrictive condition of introducing previously, in the middle of program can detect, being arranged a bit of time is that single-point is pressed, namely program first detects K1 and presses, and through a bit of time, K2 just detected 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 _Z2Impact):

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

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 the particular location of 2, as long as we process respectively X and the Y-axis of touch-screen according to the method, just can on conventional, electric-resistance is shielded, realize the detection of 2 touch locations.

Performing step is as follows:

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

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

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

Press the second contact, starts to calculate the second point coordinate.

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

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

Claims (2)

1. method that realizes 2 touch recognition of electric resistance touch screen on mobile phone, use four GPIO mouth GPIO1～GPIO4 to realize reference voltage and ground input, can scan simultaneously, use four ADC analog to digital converter ADC1～ADC4 on the handset processes device to carry out the inspection of voltage, in equivalent-circuit model when 2 of touch-screens touch, X+, X-and Y+, Y-means two conduction workplaces of touch-screen, Rx1, Rx2, Rx3 and Ry1, Ry2, X when Ry3 means to touch respectively, the grading resistance produced on the Y workplace, K1, K2 means to press the position of touch-screen, Rz1, resistance when Rz2 means 2 contacts,

Suppose GPIO1 output high level, the GPIO2 output low level, the voltage that ADC1 when single-point is pressed～4 are measured is V1_1～V4_1, and the voltage that ADC1 when pressing for 2～4 are measured is V1_2～V4_2, and above voltage meets following relation:

V1_1-V2_1≥V1_2-V2_2；

Three parameter L 1, L2, L3 mean respectively the touch-screen width of same label equivalent resistance, and three's summation equals the wide L of touch-screen;

According to reality, introducing a restrictive condition, when having be pressed at 2, as long as the program detection speed is enough fast, just do not have situation about pressing simultaneously for program, is all press successively or unclamp all the time; When having press at 2, in the middle of program can detect, being arranged a bit of time is that single-point is pressed, namely program first detects K1 and presses, through a bit of time, K2 just being detected presses, this pilot process can accurately obtain the K1 position, the proportionate relationship changed before and after utilizing, just can calculate the position that back K2 presses;

K1 presses separately:

L＝L1+L2+L3；

K1 and K2 press simultaneously:

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

X＝L-L3；

According to above-mentioned can be calculated by the particular location of 2, according to the method, X and the Y-axis of touch-screen are processed respectively, just can on the conventional, electric-resistance screen, realize the detection of 2 touch locations;

The method that realizes 2 touch recognition is as follows:

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

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

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

Press the second contact, starts to calculate the second point coordinate;

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

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

2. a kind of method that realizes 2 touch recognition of electric resistance touch screen on mobile phone according to claim 1 is characterized in that: described ADC also can be used as universal input output.

Images