TW201514811A - Multi-touch device, method for detecting multi-touch thereof and method for calculating coordinate - Google Patents

Abstract

A method for detecting multi-touch includes scanning a sensing line to obtain an analog data, converting the analog data into a digital data, performing a differential processing for the digital data to obtain a differential data, determining at least one touch point corresponding to the sensing line according to a threshold and the differential data, and calculating a coordinate for each touch point according to the digital data corresponding to the touch point.

Description

Touch device with multi-touch function, multi-touch detection method and coordinate calculation method thereof

The invention relates to a touch technology, in particular to a touch device with multi-touch function, a multi-touch detection method and a coordinate calculation method thereof.

The touch panel is a common user interface in current electronic products. More common touch technologies include resistive, capacitive, and optical. Among them, the capacitive touch panel has the characteristics of high accuracy, multi-touch, high durability and high touch resolution.

In the conventional touch detection method, first, all the capacitive sensors on the touch panel are fixedly scanned and the capacitance values are recorded in one cycle. Next, the capacitance value of each point is compared with a threshold value for a predetermined time. And, when the capacitance value continues to exceed the critical value for a predetermined time, it is determined that there is an effective single touch. Conversely, when none of the capacitance values exceeds the critical value, it is determined that there is no effective single touch. However, in multi-touch, in terms of hardware, the hardware detects the touch of two fingers in succession, which causes the hardware to execute the wrong command. For example, when the hardware detects the touch of the first finger, the corresponding touch command is executed immediately, but actually The user is trying to perform multi-touch. Therefore, a multi-touch detection method has been developed to avoid misjudging multi-touch as a single touch and causing malfunction.

A conventional multi-touch detection method is implemented by an Axis intersecting technique, which detects the number of fingers by detecting peaks and valleys and calculates coordinates by a centroid formula. In the touch detection, the sensing controller scans the horizontal axis and the vertical axis respectively, and converts the capacitance value of each axis into a digital signal through an analog digital converter (ADC) before judging. Here, a rising peak appears at the horizontal or vertical sensing point where the capacitive coupling occurs, and the intersection of the two axes is judged to be a valid touch point. After determining the touch point, calculate the corresponding coordinate value by the centroid formula. However, since the output value of the analog digital converter is susceptible to noise pollution, the coordinates of the calculated touch points are incorrect.

In an embodiment, a multi-touch detection method includes: scanning a sensing line to obtain an analog data, converting the analog data into digital data, and performing differential calculation on the digital data to obtain a differential data according to a valve. The value and the differential data determine at least one touch point of the corresponding sensing line, and calculate a coordinate value according to the digital data corresponding to each touch point.

In one embodiment, a coordinate calculation method includes: scanning a sensing line to obtain an analog data, converting the analog data into digital data, determining at least one touch point of the corresponding sensing line according to a threshold value and digital data, and A differential value between a plurality of sensing points adjacent to each touch point calculates a coordinate value. Wherein, each sensing point is an integer.

In one embodiment, a touch device having a multi-touch function includes: a plurality of first sensing lines, a plurality of second sensing lines, a first driving unit, a second driving unit, and a control unit.

The first sensing lines are arranged in parallel with each other. The plurality of second sensing lines are arranged in parallel with each other and are interleaved with the first sensing line. The first driving unit is electrically connected to the first sensing line, and the second driving unit is electrically connected to the second sensing line.

The control unit enables the first driving unit and the second driving unit, so that the first driving unit sequentially scans the first sensing line to generate first analog data corresponding to each first sensing line, and the second driving unit sequentially scans The second sensing line generates a second analog data corresponding to each of the second sensing lines. The first driving unit and the second driving unit respectively convert the first analog data and the second analog data into the first digital data and the second digital data. The control unit determines at least one effective touch position according to the at least one threshold value, the differential data of each first digital data, and the differential data of each second digital data. The effective touch positions are formed by one touch point on a first sensing line and another touch point on a second sensing line.

In summary, the touch device with multi-touch function, the multi-touch detection method and the coordinate calculation method thereof according to the present invention determine the number of fingers and/or calculate the coordinates in a differential manner to enhance the pair. The tolerance of noise.

110‧‧‧Touch panel

112‧‧‧First induction line

114‧‧‧Second induction line

130‧‧‧First drive unit

150‧‧‧Second drive unit

170‧‧‧Control unit

171‧‧‧Differential Module

173‧‧‧ Identification Module

175‧‧‧Comparative Module

177‧‧‧Computation Module

210‧‧‧ Scan each sensor line to get the corresponding analog data

230‧‧‧ Converting such ratio data into digital data

250‧‧‧Differentiate the digital data to obtain a differential data

270‧‧‧ Calculate the corresponding coordinate value according to the digital data corresponding to each touch point

S1‧‧‧ digital data

S2‧‧‧ digital data

f (x)‧‧‧ function

(x-1)‧‧‧Feeling points

X‧‧‧ sensing points

(x+1)‧‧‧Feeling points

(x+ δ ) ‧ ‧ coordinates

FIG. 1 is a schematic diagram of a touch device with multi-touch function according to an embodiment of the invention.

FIG. 2 is a diagram of a method for detecting multi-touch according to an embodiment of the invention flow chart.

Fig. 3 is a schematic diagram showing an embodiment of a control unit of Fig. 1.

Figure 4 is a waveform diagram of an embodiment of digital data.

Figure 5 is a digital sensed value-coordinate relationship diagram of an embodiment of a differential data.

Fig. 6 is a differential numerical value-coordinate relationship diagram of an embodiment of the second differential data.

Figure 7 is a digital sensed value-coordinate relationship diagram of another embodiment of digital data.

Referring to FIG. 1 , a touch device having a multi-touch function includes a touch panel 110 , a first driving unit 130 , a second driving unit 150 , and a control unit 170 .

The touch panel 110 includes a plurality of sensing lines. Here, the sensing lines are mainly divided into a plurality of first sensing lines 112 and a plurality of second sensing lines 114. The first sensing lines 112 each extend in the first direction, are parallel to each other, and are arranged at intervals. The second sensing lines 114 each extend in the second direction and are arranged parallel to each other and at intervals. The first direction is interleaved with the second direction. Preferably, the first direction is substantially perpendicular to the second direction. In other words, the first sensing lines 112 are interlaced with the second sensing lines 114 , and the first sensing lines 112 are substantially perpendicular to the second sensing lines 114 . The intersection of the first sensing line 112 and the second sensing line 114 is an individual insulating interval.

The first driving unit 130 is electrically connected to the first sensing line 112 , and the second driving unit 150 is electrically connected to the second sensing line 114 . Control unit 170 The first driving unit 130 and the second driving unit 150 are connected.

Referring to FIG. 2, the control unit 170 enables the first driving unit 130 and the second driving unit 150 to cause the first driving unit 130 to drive a scan signal to sequentially scan the first sensing line 112, and the second driving unit 150 to drive Another scan signal sequentially scans the second sensing line 114 (step 210).

During scanning, the first driving unit 130 can detect an analog data (hereinafter referred to as a first analog data) from the scanned first sensing line 112 (step 210). The first analog data has sensing values respectively corresponding to the plurality of sensing points on the first sensing line 112. The first driving unit 130 has an analog digital converter. Such a ratio digital converter converts the first analog data into digital data S1 (hereinafter referred to as first digital data S1), and outputs the first digital data S1 to the control unit 170 (step 230).

During scanning, the second driving unit 150 can detect an analog data (hereinafter referred to as a second analog data) from the scanned second sensing line 114 (step 210). The second analog data has sensing values respectively corresponding to the plurality of sensing points on the second sensing line 114. The second driving unit 150 has an analog-to-digital converter. Such a ratio analog converter converts the second analog data into digital data S2 (hereinafter referred to as second digital data S2), and outputs the second digital data S2 to the control unit 170 (step 230).

The control unit 170 determines whether there is one or more effective touch positions according to the first digital data S1 and the second digital data S2, thereby generating an instruction corresponding to the effective touch position. Here, the control unit 170 differentially calculates the received digital data (the first digital data S1 or the second digital data S2) to obtain a differential data, and then judges according to a threshold value and differential data. Breaking at least one touch point occurring on the sensing line (step 250). In this case, a touch point on the first sensing line 112 and another touch point on the second sensing line 114 can form an effective touch position.

When the touch point is found, the control unit 170 calculates a corresponding coordinate value according to the digital data corresponding to each touch point (step 270).

Referring to FIG. 3, in some embodiments, the control unit 170 includes a differential module 171, an identification module 173, and a comparison module 175.

The input of the differential module 171 is electrically connected to the first driving unit 130 and the second driving unit 150, and the output of the differential module 171 is electrically connected to the identification module 173. The identification module 173 is electrically connected between the differentiation module 171 and the comparison module 175.

Taking the first direction as the X-axis direction and the second direction as the Y-axis direction, the control unit 170 processes the X-axis coordinates (corresponding to the first sensing line 112) and the Y-axis coordinates (corresponding to the second sensing line 114). The same, so the following only describes the X-axis coordinates in detail.

Here, the digital data output from the analog digital converter to the corresponding sensing line of the differential module 171 is as shown in FIG. 4.

Referring to Figure 4, the digital data shown in the figure has a peak. Generally speaking, when the digital sensed value of the peak exceeds the threshold, a touch point exists.

Here, the control unit 170 can differentiate the data for judgment to improve the tolerance to noise.

In some embodiments, the differentiation module 171 performs the second derivative of the received digital data (the first digital data S1 or the second digital data S2). Get a second differential data.

Taking the digital data shown in Figure 4 as an example, the digital data is differentiated, that is, f ( x )- f ( x -1) is executed to obtain a differential data (as shown in Fig. 5). As can be seen from Fig. 5, in Fig. 4, the corresponding position of the peak is shown to have a point of intersection from a positive value to a negative value.

Then differentiate the first differential data in Fig. 5, that is, execute f ( x )=( f ( x +1)- f ( x ))-( f ( x )- f ( x -1)) to get two Sub-differential data (as shown in Figure 6). As can be seen from Fig. 5, in Fig. 4, the corresponding position of the peak is shown to have an extreme value.

Therefore, the identification module 173 receives the secondary differential data from the differential module 171 and detects the extreme value of the secondary differential data. The comparison module 175 then takes the absolute value obtained by the identification module 173 as an absolute value and compares the absolute value with a threshold. When the absolute value is greater than the threshold, the comparison module 175 determines that a touch occurs at the location of the extreme value, that is, the touch point exists. When the absolute value is not greater than the threshold, the comparison module 175 determines that there is no touch at the location of the extreme value, that is, the non-touch point exists.

Here, the control unit 170 further includes a calculation module 177. The comparison module 175 is electrically connected between the identification module 173 and the calculation module 177. When the comparison module 175 determines that the touch point exists, the calculation module 177 calculates the coordinate value according to the digital data corresponding to the touch point.

Here, the calculation principle of the calculation module 177 is as follows.

Assume that the digital data corresponding to a first sensing line 112 is as shown in FIG. Here, the function f (x) represents a curve of the digital sensed value passing through three points of the sensing point (x-1), x, (x+1), and the like. The highest point of the peak occurs at the coordinate value (x + δ ), which is the touch point.

The Taylor expansion is performed for f '(x+ δ ), as shown in the following equation: f ^' ( x + δ ) = f ^' (x) + δ . f ^" ( x )+... Equation 1

Since the slope of the highest point is 0, that is, f '(x + δ ) = 0, and Taylor's high-order term is ignored, the following equation 2 can be obtained: f ^' ( x ) + δ . f ^" ( x ) = 0

And Equation 2 can be derived from Equation 2:

Therefore, the coordinate value (x+ δ ) of the highest point can be obtained by the first derivative f '(x) of the function f (x) of the sensing point x and the second derivative f "(x).

Among them, the first differential f '(x) and the second differential f "(x) are the following formulas 4 and 5, respectively:

f ^" ( x )= f ( x +1) - 2 f ( x ) + f ( x -1)

Substituting Equations 4 and 5 into Equation 3 yields Equation 6 below:

As can be seen from Equation 6, the calculation module 177 can utilize the differential value ( f ( x +1) - f ( x )) of the sensing point x and the sensing point (x+1) and the sensing point (x-1) and the sensing point. The differential value of x ( f ( x )- f ( x -1)) is calculated as the coordinate value (x+ δ ) of the touch point.

Taking the digital data shown in Figure 4 as an example, the highest point of the peak appears at x=9 (the digital sensed value of the digital data is 24), and the sensing points on both sides of the highest point are x=8 (the digit thereof) The sensed value is 22) and x = 10 (the digital sensed value is 21). The calculation module 177 calculates the coordinate value (x+ δ ) of the touch point according to Equation 6 and the corresponding digital data, and obtains x+ δ = 8.9. That is, the centroid coordinates of the touch point are located at 8.9.

In summary, the touch device with multi-touch function, the multi-touch detection method and the coordinate calculation method thereof according to the present invention determine the number of fingers and/or calculate the coordinates in a differential manner to enhance the pair. The tolerance of noise.

While the present invention has been described above in the foregoing embodiments, it is not intended to limit the invention, and the invention may be modified and modified without departing from the spirit and scope of the invention. The scope of patent protection shall be subject to the definition of the scope of the patent application attached to this specification.

210‧‧‧ Scan each sensor line to get the corresponding analog data

230‧‧‧ Converting such ratio data into digital data

250‧‧‧Differentiate the digital data to obtain a differential data

270‧‧‧ Calculate the corresponding coordinate value according to the digital data corresponding to each touch point

Claims (10)

A multi-touch detection method includes: scanning a plurality of sensing lines to obtain corresponding analog data; converting each analog data into a digital data; performing differential calculation on each digital data to obtain a differential data; A threshold value and each of the differential data determine at least one touch point that occurs on the corresponding sensing line; and calculate a coordinate value according to the digital data corresponding to each touch point. The method for detecting multi-touch according to claim 1, wherein the step of calculating the differential is to perform secondary differentiation on the digital data. The method for detecting multi-touch according to claim 1, wherein the detecting step comprises: comparing an absolute value of each extreme value in the differential data with the threshold; and when the absolute value is greater than the threshold When it is determined that the touch point exists. The method for detecting multi-touch according to claim 1, wherein the calculating step calculates the coordinate value according to the following formula: Wherein, the X+ δ represents the coordinate value, the X is a previous sensing point of the touch point, the f () is a function of a curve passing through the corresponding sensing point, and each of the sensing points is an integer. A coordinate calculation method includes: scanning a plurality of sensing lines to obtain respective corresponding analog data; Converting each of the analog data into a digital data; determining, according to a threshold value and each of the digital data, at least one touch point occurring on the corresponding sensing line; and between the plurality of sensing points adjacent to each of the touch points The plurality of differential values calculate a coordinate value, wherein each of the sensing points is an integer. The coordinate calculation method according to claim 5, wherein the calculating step calculates the coordinate value according to the following formula: Wherein, the X+ δ represents the coordinate value, the X is a previous sensing point of the touch point, the f () is a function of a curve passing through the corresponding sensing point, and each of the sensing points is an integer. A touch device with multi-touch function includes: a plurality of first sensing lines arranged in parallel with each other; and a plurality of second sensing lines arranged in parallel with each other and interlaced with the first sensing lines; a first driving unit Electrically connecting the first sensing lines to sequentially scan the first sensing lines to generate a first analog data corresponding to each of the first sensing lines, and converting each of the first analog data into a first digital position a second driving unit electrically connecting the second sensing lines to sequentially scan the second sensing lines to generate a second analog data corresponding to each of the second sensing lines, and each of the second Converting analog data into a second digit data; a control unit for determining the first driving unit and the second driving unit, and determining at least one effective touch according to the at least one threshold, the differential data of each of the first digital data, and the differential data of each of the second digital materials a position, wherein each of the effective touch positions is formed by a touch point on one of the first sensing lines and another touch point on one of the second sensing lines. The touch device with multi-touch function as described in claim 7, wherein each of the differential data is a second-order differential data. The touch device with multi-touch function as described in claim 7, wherein the control unit is configured to compare an absolute value of each extreme value in each of the differential data with the threshold, and when the absolute value is greater than the At the threshold, it is determined that the touch point exists. The touch device with multi-touch function as described in claim 7, wherein the control unit is configured to calculate coordinate values of each touch point according to the following formula: Wherein, the X+ δ represents the coordinate value, the X is a previous sensing point of the touch point, the f () is a function of a curve passing through the corresponding sensing point, and each of the sensing points is an integer.