CN102880366A

CN102880366A - Capacitive touch screen temperature drift characteristic detection method and detection system

Info

Publication number: CN102880366A
Application number: CN2012103127039A
Authority: CN
Inventors: 张晋芳; 章军富
Original assignee: BEIJING JICHUANG NORTHERN TECHNOLOGY CO LTD
Current assignee: Chipone Technology Beijing Co Ltd
Priority date: 2012-08-29
Filing date: 2012-08-29
Publication date: 2013-01-16
Anticipated expiration: 2032-08-29
Also published as: CN102880366B

Abstract

The invention provides a capacitive touch screen temperature drift characteristic detection method and a capacitive touch screen temperature drift characteristic detection system. According to the method and the system, whether the temperature drift of a touch screen occurs is judged by continuously monitoring the change of a mutual capacitance value deviation. The method comprises the following steps of: first, measuring a mutual capacitance value among all drive lines and sense lines of a capacitive touch screen to serve as a reference; then, performing sampling measurement on a capacitance value formed by an electrode matrix according to a certain step length periodically; next, calculating the deviation between the capacitance value and a corresponding coordinate reference value, counting the number of the points of the deviation values falling outside a predetermined threshold value range; and finally, when the number of the points is greater than a predetermined standard value, judging that the capacitive screen has the temperature drift. The method and the system can realize detection fast and efficiently, easily realize programming and are high in expandability.

Description

A kind of capacitance touch screen temperature is floated characteristic detecting method and detection system

Technical field

The present invention relates to a kind of capacitance touch screen temperature and float characteristic detecting method and detection system, especially refer to touch-screen mutual capacitance measured value is subjected to the variable effect such as environment temperature, humidity and the deviation that produces detects and temperature is floated the method for judgement.

Background technology

Touch-screen product on the market can be divided into resistive touch screen, photo-electric touch-screen, surface acoustic wave touch screen and capacitive touch screen etc. according to its structural principle.

Capacitance touch screen is also becoming the mainstream product in the market because the advantages such as it is sturdy and durable, reaction velocity fast, saving space have obtained increasing application in various electronic device field.Its principle of work as shown in Figure 1, make the overlapping electrod-array of transverse and longitudinal at glass baseplate surface with ITO (indium tin oxide), horizontal and vertical ITO electrode crossing place forms several Inductance and Capacitance, also be the two poles of the earth that two arrays of electrodes consists of respectively electric capacity, when occuring to touch, touch place adjacent electrode coupling situation changes, thereby the mutual capacitance value changes, by the change of scan capture to capacitance, namely obtain touch location.The touch-screen that consists of take 4 lines, 4 alignments is as example, the electrode of line and alignment; Consist of respectively the two poles of the earth of Inductance and Capacitance, when the position of pixel 103 correspondences on the finger touch screen, near two electrode couplings the pixel 103 change, cause the variation of Inductance and Capacitance 105 values, 102 pairs of lines of driving circuit, also be that drive wire drive line100 timesharing applies the driving signal successively, alignment, also be that sense wire sense line104 carries out sensing by column, sensing signal obtains the position coordinates of touch point by operational amplifier 106 and output by the variation that detects corresponding capacitance.

As everyone knows, semiconductor devices is subjected to the impact of the factors vary such as environment temperature, humidity, and its output signal can produce deviation, thereby causes electrical specification to present drift.Capacitance touch screen is owing to scribble the ITO electrode layer on its glass substrate, its four limit is provided with silver slurry electronic circuit and is connected with the ITO layer, because the silver slurry is to temperature, humidity sensitive, in addition, some part characteristics of sweep circuit, connecting circuit also exist temperature to float, coupling capacitance output signal after the ADC conversion also can be subjected to the impact of temperature and produce deviation, and above-mentioned composite factor causes the touch position coordinates location may produce deviation, thereby produces the problem of location drift and maloperation.Fig. 2 be the capacitance touch screen coordinate points with temperature (degree centigrade) curve that changes, can find out that directional drift has appearred in 3 output valve RAW1, RAW2, the RAW3s of capacitance detecting after the AD conversion.Therefore need to float characteristic to the touch-screen temperature and detect, thereby floating to proofread and correct for targetedly temperature drift compensation and temperature provides the basis.

Summary of the invention

The present invention propose a kind of efficiently, the capacitance touch screen temperature is floated characteristic detecting method and detection system accurately, its variation by the continuous monitoring variation in capacitance value judges whether touch-screen temperature occurs float.

Capacitance touch screen for a M*N, this method at first records all M root drive wire Drive line, and the mutual capacitance value between the N root sense wire is as benchmark, then regularly by certain step-length S the electric capacity that electrode matrix consists of is carried out sampled measurements, and calculate deviation between capacitance and the respective coordinates reference value, the statistic bias value drops on counting outside the predetermined threshold value scope [Th, Th], when this counts more than the standard value of presetting, judge that then capacitance plate exists temperature to float.

This method is preferably when detecting end S time, each testing result is compared, only have when each result is all identical or roughly the same, judge that just testing result is effective, in order further to increase the algorithm confidence level, this method is duplicate measurements n cycle as stated above, when the result is all identical or roughly the same continuously in n cycle, judges that testing result is effective.

In this method, step-length S, threshold value Th size and reliability coefficient C determine and can rule of thumb determine in practice, consider that the composite factors such as touch-screen size and MCU loading condition choose.Step-length is less, and testing result is more credible, but it is also more to take the MCU resource.And choosing of threshold value Th, reliability coefficient C considers that the different application field is to the requirement of coordinate accuracy, in the demanding occasion of positioning accurate accuracy, choosing of threshold value Th is less, corresponding temperature drift compensation frequency is also higher, require lower occasion at the positioning accurate accuracy, choosing of threshold value Th, C can be larger, thereby improve detection speed.

Adopt the touch-screen temperature of the detection method of the present invention's proposition to float the Characteristics Detection system, comprise control module, capacitance touch screen, capacitance touch screen driver module and memory module.

For the capacitance touch screen of a M*N, comprise the steps: when adopting this method to detect

At first, at the T0 that do not touch constantly, drive successively M root drive wire Drive line, and N root sense wire sense line is scanned successively, thereby record mutual capacitance value C between all lines and the alignment _Ij, i, j represent electrode matrix row, column coordinate, all capacitance detecting values form capacitance Matrix C [i, j], order matrix B[i, j]=C[i, j], it as benchmark, and is arranged reliability coefficient C, step-length S, threshold value Th.

Secondly, constantly carry out the i time sampling at Ti, choose as follows sample point coordinate and detect the mutual capacitance value;

x＝i+j*S，j＝0，1，…，[(N-i)/S]

y＝i+k*S，k＝0，1，…，[(M-i)/S] (1)

Record Cxy and with Criterion-matrix in the capacitance Bxy of respective coordinates ask poor:

Dxy=Cxy-Bxy; Statistic bias matrix D [X, Y] (wherein, X=[(N-i)/S]+1, Y=[(M-i)/S]+1) in deviation greater than the n1 and less than the n2 that counts of-Th of counting of Th;

Secondly, determine whether to exist drift based on default reliability coefficient C,

N1＞X*Y*C then exists the forward temperature to float; N2＞X*Y*C then exists the negative sense temperature to float.

Secondly, when S sample detecting all finishes, judge according to the result of all S time detection, if come to the same thing or roughly the same at every turn, judge that then the testing result of temperature drift characteristic is credible, thereby can realize targetedly correction of temperature drift to contact coordinate.

The method that the present invention proposes is easy to programming realization, low to hardware requirement, can float characteristic to the touch-screen temperature and realize efficient, the accurate detection, and favorable expandability can pass through to revise the different application scenario of parameter adaptation.

Description of drawings

Fig. 1 is the capacitance touch screen principle of work.

Fig. 2 is the temperature variant curve of capacitance touch screen fixed point coordinate.

Fig. 3 is the touch-screen detection system structured flowchart that the present invention proposes.

Fig. 4 is detection method software algorithm flow process of the present invention.

Fig. 5 a-5c is the coordinate synoptic diagram of the 1-3 time measurement sampled point in the embodiment of the invention.

Embodiment

Fig. 3 is the structured flowchart of detection system of the present invention, and it comprises control module 1, capacitance touch screen 2, capacitance touch screen driver module 3 and memory module 4.Control module 1 links to each other with touch-screen driver module 3, touch-screen driver module 3 links to each other with touch-screen 2, and it can arrange driving voltage, finishes the driven sweep to the capacitance plate electrode matrix, memory module 4 available non-volatile memory realize, are used for storage correlation parameter and reference value.

Fig. 4 is the algorithm realization flow figure of detection method of the present invention.

The below is elaborated to detection method of the present invention take the capacitance touch screen of a 15*10 as example.

At first, detection step-length S=3 is set, threshold value Th=50, reliability coefficient C=0.5 at the T0 that does not touch constantly, drives 15 drive wire Drive line successively, and 10 sense wire sense line are scanned successively, thereby record mutual capacitance value C between all lines and the alignment _Ij, i, j represent electrode matrix row, column coordinate, all capacitance detecting values form capacitance Matrix C [15,10], order matrix B=C, with it as benchmark;

Secondly, choose as follows sample point coordinate constantly at Ti and detect the mutual capacitance value, Fig. 5 has shown respectively the coordinate points that 3 samplings are chosen;

x＝i+j*S，j＝0，1，…，[(10-i)/3]

y＝i+k*S，k＝0，1，…，[(15-i)/3] (1)

Dxy＝Cxy-Bxy；

Deviation is greater than 50 the n1 and less than-50 the n2 that counts of counting in the statistic sampling point;

N1＞X*Y*0.5 then exists the forward temperature to float; N2＞X*Y*0.5 then exists the negative sense temperature to float.

When 3 sample detecting all finish, judge according to the result who detects for all 3 times, if come to the same thing or roughly the same at every turn, judge that then the testing result of temperature drift characteristic is credible.

The above only is preferred embodiment of the present invention, not in order to limiting the present invention, all any modifications of making within the spirit and principles in the present invention, is equal to and replaces and improvement etc., all should be included within protection scope of the present invention.

Claims

1. a capacitance touch screen temperature is floated characteristic detecting method, at first record mutual capacitance value between all drive wire Drive line and the sense wire Sense line as benchmark, then regularly by certain step-length S the electric capacity that electrode matrix consists of is carried out sampled measurements, and the deviation between calculating sampling capacitance and the respective coordinates reference value, the statistic bias value drops on predetermined threshold value scope [Th, Th] outside count, when this counts more than default standard value, judge that then touch-screen exists temperature to float.

2. detection method as claimed in claim 1, it comprises the steps:

At first, at the T0 that does not touch constantly, drive successively M root drive wire Drive line, and N root sense wire Sense line scanned by column, thereby record all mutual capacitance value Cij, and with it as benchmark, and reliability coefficient C, step-length S, threshold value Th are set.

Secondly, constantly carry out the i time sampling at Ti, choose as follows sample point coordinate and detect mutual capacitance value Cxy;

x＝i+j*S，j＝0，1，…，[(N-i)/S]

y＝i+k*S，k＝0，1，…，[(M-i)/S]

Secondly, by poor, and statistic bias reaches the n2 that counts less than-Th greater than the n1 that counts of Th with Cxy and respective coordinates reference capacitance value;

At last, described default standard value is determined based on default reliability coefficient C, judges whether to exist drift by following formula,

N 1＞X*Y*C then exists the forward temperature to float,

N 2＞X*Y*C then exists the negative sense temperature to float, wherein, and X=[(N-i)/S]+1, Y=[(M-i)/S]+1.

3. detection method as claimed in claim 2 when S sample detecting all finishes, is judged according to the result who detects for all S time, if come to the same thing or roughly the same at every turn, judges that then the testing result of temperature drift characteristic is credible.

4. detection method as claimed in claim 3, step-length S=3, threshold value Th=50, reliability coefficient C=0.5.

5. detection method as claimed in claim 2 or claim 3, by n cycle of described step duplicate measurements, when n interior testing result of consecutive periods was all identical or roughly the same, the judgement testing result was effective.

6. detection method as claimed in claim 5, measuring period n=30.

An employing as claim 1-6 as described in each capacitance touch screen temperature of detection method float the Characteristics Detection system, it comprises control module, capacitance touch screen, capacitance touch screen driver module and memory module, control module links to each other with the touch-screen driver module, and the touch-screen driver module links to each other with touch-screen.