KR102092665B1 - Apparatus and method for calculating coordinates in differential touch sensing system - Google Patents

Abstract

The present invention discloses a coordinate selection circuit and method for obtaining correction coordinates corresponding to a touch in a differential touch sensing system that detects a change in capacitance in a differential manner, wherein the coordinate selection device of the differential touch sensing system is recognized as a touch area. A partial region accumulating unit converting partial differential values into accumulation values; A maximum data determination unit that determines coordinates having a maximum value among the accumulated values as maximum coordinates; And removing the average noise value from the accumulated values of two or more adjacent coordinates based on the maximum coordinate and the maximum coordinate to obtain modeling values, obtain displacement using the modeling values, and apply the displacement to the maximum coordinate. Characterized in that it comprises a; coordinate calculation unit for obtaining the correction coordinates for the touch.

Description

Coordinate calculation device and method of differential touch sensing system {APPARATUS AND METHOD FOR CALCULATING COORDINATES IN DIFFERENTIAL TOUCH SENSING SYSTEM}

The present invention relates to a differential touch sensing system, and more particularly, to a coordinate calculation apparatus and method for obtaining actual coordinates corresponding to a touch in a differential touch sensing system that differentially senses a change in capacitance due to a touch.

Recently, a display panel composed of a mobile device or the like employs a lot of touch functions.

In this case, most display panels are implemented as flat panel display devices such as liquid crystal displays, and the touch function is implemented as a touch panel combined with a display panel.

The touch panel means a transparent switch panel having a function of operating a device or executing a program according to a user pressing a text, an image or an icon.

The touch panel may be configured to perform capacitive touch recognition, and as an example of a touch panel that implements capacitive touch recognition, a "mutual capacitance touch sensing device" is disclosed as "US Patent Publication No. US 2009/0091551". have.

A typical touch sensing system is sometimes developed to sense differentially in order to sense the correction capacity.

When the sensing signal is driven in a differential manner, the touch sensing system is resistant to noise and can be expected to improve the touch sensitivity and the accuracy of sensing.

Recently, applications to which a touch sensing system is applied, such as a mobile device, have been developed to implement high functionality. Accordingly, there is a need to improve the function to provide accurate coordinates in response to the touch so that the touch sensing system can also implement a high function.

An object of the present invention is to provide an apparatus and method for calculating a coordinate of a differential touch system that calculates correction coordinates that approximate actual coordinates from sensing data having a differential value corresponding to a touch of a touch panel.

In addition, the present invention converts a portion recognized as a touch area into an accumulation value having a weighted value for a positive value, and calculates coordinates according to the distribution of the accumulation values to calculate a correction coordinate approximating actual coordinates. Another object is to provide an apparatus and method for calculating coordinates of a sensing system.

In addition, the present invention is a differential touch sensing system that calculates correction coordinates approximating actual coordinates by converting a differential value of a portion recognized as a touch area into an accumulation value and performing modeling in consideration of noise and calculating coordinates as a modeling result. Another object is to provide a coordinate calculation device and method.

The coordinate selection device of the differential touch sensing system according to the present invention includes: a partial region accumulation unit that converts differential values of a portion recognized as a touch region into accumulation values; A maximum data determination unit that determines coordinates having a maximum value among the accumulated values as maximum coordinates; And obtaining modeling values obtained by removing an average noise value from the accumulated values of two or more adjacent coordinates based on the maximum coordinates and the maximum coordinates, obtaining a displacement using the modeling values, and applying the displacement to the maximum coordinates. Characterized in that it comprises a; coordinate calculation unit for obtaining the correction coordinates for.

In addition, the coordinate calculation method of the differential touch sensing system according to the present invention comprises: recognizing a touch area from sensing data; Converting differential values of the touch area into accumulation values; Determining a coordinate having a maximum value among the accumulated values as a maximum coordinate; Obtaining modeling values by removing an average noise value from the accumulated values of two surrounding coordinates before and after the scan direction of the sensing line based on the maximum coordinate and the maximum coordinate; Obtaining a displacement from the modeling values; And obtaining correction coordinates for the touch by applying the displacement to the maximum coordinates.

According to the present invention, it is possible to calculate correction coordinates approximating actual coordinates from sensing data having a differential value, thereby providing correction coordinates corresponding to a touch.

In addition, according to the present invention, it is possible to provide correction coordinates that approximate the actual coordinates of a portion recognized as a touch area by converting them into accumulated values having a weight.

In addition, according to the present invention, it is possible to provide correction coordinates approximating actual coordinates by calculating coordinates using modeling considering noise.

1 is a block diagram showing a preferred embodiment of the coordinate calculation circuit of the differential touch sensing system according to the present invention.
Figure 2 is a detailed block diagram of the digital logic unit of Figure 1;
3 is a data map explaining the conversion of differential values to accumulation values.
4 is a waveform diagram for explaining the conversion of the differential values of the scan line R1 of FIG. 3 (a) into an accumulated value.
5 is a waveform diagram for explaining the conversion of the differential values of the scan line R2 of FIG. 3 (b) into an accumulated value.
6 is a data map illustrating that the maximum value is determined.
7 is a graph for explaining a method for obtaining actual coordinates from modeling values.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The terms used in the present specification and claims are not interpreted as being limited to ordinary or dictionary meanings, and should be interpreted as meanings and concepts consistent with the technical matters of the present invention.

The embodiments illustrated in the specification and the drawings shown in the specification are preferred embodiments of the present invention and do not represent all of the technical spirit of the present invention, and various equivalents and modifications that can replace them at the time of this application It can be.

The coordinate calculation circuit and method of the differential touch sensing system according to the present invention discloses a technique of using a weighted accumulation value, modeling the accumulated value in consideration of noise, and obtaining correction coordinates from the modeled value.

The present invention may be implemented on a differential touch sensing system as shown in FIG. 1, and may be implemented by analyzing sensing data output from an image buffer.

Referring to FIG. 1, the differential touch sensing system may include a PWM control unit 10, a driving circuit 12, a touch panel 14, a sensing circuit 16 and an image buffer 18.

The PWM control unit 10 provides a driving pulse for periodic sensing.

The driving circuit 12 provides a driving signal synchronized with the driving pulse to the touch panel 14. At this time, the driving signal may be provided to the touch panel 14 in a differential manner.

The touch panel 14 includes a plurality of driving lines (not shown) and a plurality of sensing lines (not shown). The plurality of driving lines and the plurality of sensing lines may be variously formed according to a manufacturer's intention, and may be generally formed to cross each other or to be arranged side by side to share the electrostatic capacity of spaced apart space.

Therefore, a driving signal is applied to the driving line, and a sensing signal is output from the sensing line. In addition, when a change in capacitance occurs by a touch, the sensing signal outputs a sensing signal reflecting the change in capacitance.

That is, the touch panel 14 is configured to output the sensing signal corresponding to the periodically applied driving signal in a differential manner.

The sensing circuit 16 transmits a sensing signal applied differentially from the touch panel 14 to the image buffer 18. Here, the sensing circuit 16 may be configured to perform functions such as amplification of the sensing signal or noise filtering.

The image buffer 18 may be configured to include a frame-based storage that can accommodate one frame of the touch panel 14, and converts and stores the analog signal transmitted from the sensing circuit 16 to have a digital value. It can be configured to output. That is, the image buffer 18 outputs sensing data as a digital signal.

Hereinafter, the digital logic unit 20 configured as an embodiment according to the present invention to be described receives sensing data, which is a digital signal output from the image buffer 18, and the sensing data received by the digital logic unit 20 is touched. It may be expressed in the form of raw data for the frame of the panel 14. The raw data refers to data having a differential value to which digital values are mapped by being divided according to positions of a plurality of scan lines with respect to a frame area of the touch panel 14.

The digital logic unit 20 of FIG. 1 may be implemented with firmware for calculating coordinates in a chip, and functionally divided and illustrated, it may be exemplified as having the configuration shown in FIG. 2.

That is, the digital logic unit 20 includes a touch area recognition unit 30, a noise determination unit 32, a partial area accumulation unit 34, a maximum data determination unit 36, and a coordinate calculation unit 38 Can be.

Here, the touch area recognition unit 30 has a function of recognizing a touch area from sensing data having a differential value for each coordinate.

The touch area recognition unit 30 receives sensing data from the image buffer 18, and the sensing data is raw data to which differential values are mapped as described above, and may include raw data as shown in FIG. 3 (a).

The touch area recognition unit 30 performs labeling by determining whether differential values included in the sensing data have a predetermined threshold value or more. Labeling includes the meaning of counting by recognizing the position.

That is, areas having differential values above a threshold value are labeled, and the labeled area can be recognized as a touch area.

At this time, the level selected according to the intention of the manufacturer may be applied in consideration of the characteristics of the differential values. And, in response to a characteristic in which the differential values have a pattern in which the positive value and the negative value are repeated, the threshold value is a positive value for contrasting the differential values of the positive value and a negative value for contrasting the differential values of the negative value. Each can be set to have. Accordingly, positions having a differential value equal to or less than the threshold of the negative value may be labeled and recognized as a touch area.

The noise determination unit 32 determines whether the touch area recognized by the touch area recognition unit 30 is recognized due to noise or by a normal touch.

When it is determined that the touch area is recognized by the normal touch, the noise determination unit 32 transfers the differential values recognized as the touch area to the partial area accumulation unit 34. On the other hand, if it is determined that the touch area is recognized by the noise, the noise determination unit 32 stops the process for calculating coordinates.

The noise determination unit 32 may determine with a normal touch when a valid positive value and a valid negative value for the scanning direction of the sensing line are continuous.

Here, the sensing line corresponds to the sensing line of the touch panel 14 and the scan direction may be illustrated in the direction of the arrows A1 and A2 pointing from the right to the left of FIG. 3 (a).

The waveform corresponding to the sensing line R1 of FIG. 3 (a) is FIG. 4 (a), and the waveform corresponding to the sensing line R2 is FIG. 5 (a).

Looking at the differential values of FIGS. 3 (a), 4 (a) and 5 (a), it can be seen that the valid positive values and the valid negative values continue as the differential values proceed in the direction of the arrows A1 and A2. You can.

Accordingly, the touch area represented by the differential values of FIGS. 3 (a), 4 (b), and 5 (a) may be determined as a normal touch.

In the above description, a valid positive value means having a value greater than or equal to a threshold set as a positive value, and a valid negative value means having a value greater than or equal to a threshold set as a negative value. At this time, the threshold value may be the same as or different from the value applied by the touch area recognition unit 30 described above.

If, when the valid positive value and the valid negative value for the scanning direction of the sensing line are not continuous, that is, if there is only a negative value or only a positive value, the noise determination unit 32 determines the area recognized as noise and ends the coordinate calculation process. do.

If it is determined in the noise determination unit 32 that the touch area is recognized by the normal touch, the partial area accumulation unit 34 receives differential values for the touch area.

The partial region accumulation unit 34 has a configuration that performs partial region accumulation that converts differential values for the touch region to accumulation values as shown in FIG. 3 (b).

Here, the partial region accumulation unit 30 may calculate accumulation values for the touch region by sequentially integrating differential values corresponding to one sensing line of the touch panel 14 in one direction.

More specifically, the values of '41', '45', '-59', and '-43' are sequentially connected to the differential values of the scan line R1 of FIG. 3A. When the differential values of FIG. 3 (a) are accumulated along the scan direction A1, the accumulated values are '41', '86', '27', and '-16' as the scan line R1 of FIG. 3 (b). Is converted to the value of

The accumulated value '86' is derived as the sum of '41' and '45' of the differential values, and the accumulated value '27' is derived as the sum of the previous accumulated value '86' and the differential value '-59', and the accumulated value ' -16 'is derived as the sum of the previous accumulated value' 27 'and the differential value' -43 '.

The differential values of the scan line R2 of FIG. 3 (a) can also be converted as in FIG. 3 (b) by the above-described method. 4 (b) and 5 (b) are waveforms applying the accumulated values of each scan line R1, R2 of FIG. 3 (b).

 The accumulated value converted as described above is an exemplary value obtained by converting a portion recognized as a touch area to have a weighted value for a positive value.

As described above, when the accumulation value conversion for the touch area is performed in the partial area accumulation unit 34, the maximum data determination unit 36 receives the accumulation values for the touch area and has the maximum value among the accumulation values. Performs an operation to determine the maximum coordinates.

That is, the maximum data determination unit 36 finds the maximum coordinates among the accumulated values of the touch area having the map structure as shown in FIG. 6. In FIG. 6, the maximum coordinate may be determined as a coordinate whose accumulation value is described as '215'.

The coordinate calculating unit 38 receives the accumulated values for the touch area of the partial region accumulation unit 34 and receives the coordinates determined as the maximum coordinates by the maximum data determination unit 26.

Accordingly, the coordinate calculator 38 removes DC noise from accumulated values of two or more adjacent coordinates based on the maximum coordinate and the maximum coordinate to obtain modeling values.

In an embodiment according to the present invention, the coordinate calculator 38 illustrates using accumulated values of two surrounding coordinates before and after the scanning direction of the sensing line based on the maximum coordinates and the maximum coordinates included in the region D of FIG. 6. .

Referring to FIGS. 6 and 7, the maximum coordinates are represented by x on the coordinate axis, and the peripheral coordinates are represented by x-1 and x + 1. The accumulated value corresponding to the maximum coordinate x is represented by w _x , the accumulated value corresponding to the peripheral coordinate x-1 is represented by w _x-1 , and the accumulated value corresponding to the peripheral coordinate x + 1 is represented by w _{x + 1} . Display.

The accumulation value w _x corresponding to the maximum coordinate x is illustrated as having '215' in FIG. 6, and the accumulation value w _x-1 corresponding to the peripheral coordinate x-1 is illustrated as having '71' in FIG. 6. The accumulation value w _{x + 1} corresponding to the peripheral coordinates x + 1 is illustrated as having '121' in FIG. 6.

6 and 7 illustrate that applied in the opposite direction to the scan directions A1 and A2 illustrated in FIG. 3.

The coordinate calculator 38 obtains modeling values by removing the average value of DC noise from the accumulated values of the adjacent coordinates x-1 and x + 1 based on the maximum coordinate x and the maximum coordinate x.

DC noise refers to unspecified noise formed by parasitic capacitance and can be formed at multiple locations along the sensing line and detected by labeling.

DC noise applies the actual measured value, and the modeling value is obtained by applying the average value n _x which calculated the noise. The mean value calculated for the noise n _x can be calculated differently according to the location since the difference sum of the noise that is applied to the mean value _x n in accordance with the progress of the scan on the sensing line. In an embodiment according to the present invention, the average value for calculating the noise of the maximum coordinate x is defined as n _x , and the average value for calculating the noise of the peripheral coordinates x-1 and x + 1 is n _x-1 and n _{x + 1} . define.

Consequently, the modeling value can be obtained by removing the average value of DC noise from the accumulated value, so the modeling value of the maximum coordinate x can be obtained as w _x -n _x , and the modeling value of the peripheral coordinate x-1 is w _x-1- It can be obtained by n _x-1 , and the modeling value of the peripheral coordinates x + 1 can be obtained by w _{x + 1} -n _{x + 1} .

When the correlation between the accumulated value for each coordinate and the average value of DC noise as described above is calculated using an exponential model, it can be expressed as <Equation 1> to <Equation 3> below. <Equation 1> is a modeling value of the maximum coordinate x, <Equation 2> is a modeling value of the peripheral coordinate x-1, and <Equation 3> is a modeling value of the peripheral coordinate x + 1.

Here, C is an amplitude, x ₀ is a correction coordinate, and x, x-1, x + 1 are modeling values w _x -n _x, w _x-1 -n _x-1, w _{x + 1} -n The coordinate of the position corresponding to _{x + 1} , and K is the variance coefficient of the function.

As described above, after obtaining the modeling value, the displacement δ may be obtained from the modeling values, and the correction coordinate x ₀ for the touch may be obtained by applying the displacement δ to the maximum coordinate x.

At this time, the displacement δ means the difference between the coordinate having the maximum value and the correction coordinate, and if the displacement δ has a positive (+) value, it means that the correction coordinate is located after the coordinate having the maximum value, and the displacement δ is negative (- ) Value means that the correction coordinate is located before the coordinate with the maximum value.

The displacement δ can be obtained by Equation 4 below.

Here, δ _x is the displacement of the x coordinate, w _x , w _{x -1} and w _{x +1} are accumulation values for touch differential values for each coordinate, and n _x , n _{x -1} and n _{x +1} are It is an average value of the DC noise for each coordinate.

When the displacement δ is obtained as described above, the actual coordinates can be obtained as shown in <Equation 5> below.

In the above-described embodiment, a value expressed as a function of log ₂ (S) can be expressed as an approximation to obtain the displacement δ. Here, S is a variable having a correlation between modeling values applied to the log ₂ function as shown in <Equation 4>.

At this time, the approximation may be calculated and applied as an experimental value for the simplification of the algorithm for implementing the configuration and method of the apparatus. When the variable value of each log2 function for obtaining the displacement δ by the experimental value is obtained by S1 and S2, the displacement δ can be expressed as <Equation 6> below.

에 대응하여 미리 설정된 근사값이고, S2는

에 대응하여 미리 설정된 근사값이며, δ_x는 x좌표의 변위이며, w_x, w_{x -1} 및 w_{x +1}은 좌표 별 터치 차동값들에 대한 축적값이고, n_x, n_{x -1} 및 n_{x +1}은 좌표별 상기 DC 노이즈 평균값이다.Where S1 is

Corresponding to a preset approximation, S2 is

Corresponding to a preset approximation, δ _x is the displacement of the x coordinate, w _x , w _{x -1} and w _{x +1} are accumulation values for touch differential values for each coordinate, n _x , n _{x -1} and n _{x +1} is the average DC noise for each coordinate.

Although the calculation of the correction coordinates of the embodiment according to the present invention described above is performed for the scan line, the present invention is not limited thereto and may be performed for the driving line intersecting the scan line. In this case, correction coordinates on the driving line approximating the actual coordinates can be obtained.

Consequently, the correction coordinates (x ₀ , y ₀ ) approximating the actual coordinates can be obtained by the present invention.

Therefore, the present invention does not calculate the coordinates for the touch area recognized by noise according to the above-described embodiment, and corrects the calibration coordinates approximating the actual coordinates from sensing data having a differential value for the touch area recognized by normal touch. Can be calculated.

In addition, the present invention can provide correction coordinates approximating actual coordinates by converting differential values of the touch region recognized by the normal touch in the sensing data into accumulated values having a weight to obtain correction coordinates of the portion recognized as the touch region. have.

In addition, the present invention removes DC noise included in the accumulated value having a weight, calculates coordinates after obtaining a modeling value. Therefore, the present invention has an effect of providing correction coordinates approximating actual coordinates excluding DC noise.

10: PWM control unit 12: driving circuit
14: touch panel 16: sensing circuit
18: image buffer 20: digital logic unit
30: touch area recognition unit 32: noise determination unit
34: partial area accumulation unit 36: maximum data determination unit
38: coordinate calculation unit

Claims (14)

A partial region accumulation unit converting differential values of the portion recognized as the touch region into accumulation values;
A maximum data determination unit that determines coordinates having a maximum value among the accumulated values as maximum coordinates; And
Based on the maximum coordinate and the maximum coordinate, the average values of noise are removed from the accumulated values of two or more adjacent coordinates to obtain modeling values, displacement using the modeling values, and applying the displacement to the maximum coordinate to touch Coordinate calculation device of the differential touch sensing system comprising a; coordinate calculation unit for obtaining the correction coordinates approximating the actual coordinates for. According to claim 1,
A touch area recognition unit recognizing the touch area from sensing data having a differential value for each coordinate; And
And determining whether the touch area is noise or recognizing a normal touch, and if it is determined that the touch is normal, further includes a noise determination unit that transfers the differential values to the partial area accumulation unit. According to claim 2,
The touch area recognition unit is a coordinate calculation device of a differential touch sensing system that recognizes positions having the differential value having a predetermined threshold or more as the touch area. According to claim 2,
The noise determination unit is a coordinate calculation device of the differential touch sensing system to determine the normal touch when a valid positive value and a valid negative value for the scanning direction of the sensing line are continuous. According to claim 1,
The coordinate calculator calculates the coordinates of the differential touch sensing system by using the accumulated values of two peripheral coordinates before and after the scan direction of the sensing line based on the maximum coordinates and the maximum coordinates. The method of claim 5,
The noise is a coordinate calculation device of a differential touch sensing system that is set to an average value of noise of a DC component on a sensing line where the maximum coordinates and the peripheral coordinates are located. The method of claim 1 or 5,
The modeling values

, Where C is the amplitude, x ₀ is the correction coordinate, x is the coordinate of the position for which the modeling value is obtained, and K is the variance coefficient of the function. The method of claim 1 or 5,
The displacement is

Δ _x is the displacement of the x coordinate, w _x , w _x-1 and w _{x + 1} are the accumulated values for the touch differential values for each coordinate, and n _x , n _x-1 and n _{x + 1} are Coordinate calculation device of the differential touch sensing system which is an average value of the noise for each coordinate. The method of claim 1 or 5,
The displacement is

Is set to, S1 is

Corresponding to a preset approximation value, the S2 is

Corresponding to a preset approximation, δ _x is the displacement of the x coordinate, w _x , w _x-1 and w _{x + 1} are accumulation values for touch differential values for each coordinate, n _x , n _x-1 and n _{x + 1} is the coordinate calculation device of the differential touch sensing system, which is the average value of the noise for each coordinate. Recognizing the touch area in the sensing data;
Converting differential values of the touch area into accumulation values;
Determining a coordinate having a maximum value among the accumulated values as a maximum coordinate;
Obtaining modeling values by removing an average noise value for each coordinate from the accumulated values of two surrounding coordinates before and after the scan direction of the sensing line based on the maximum coordinate and the maximum coordinate;
Obtaining a displacement from the modeling values; And
And obtaining the correction coordinates for the touch by applying the displacement to the maximum coordinates. The method of claim 10,
Calculating coordinates of the differential touch sensing system further comprising determining whether the touch area recognized from the sensing data is noise or recognizing a normal touch and proceeding to convert the differential values into the accumulated values. Way. The method of claim 10,
The modeling values

Where C is the amplitude, x ₀ is the correction coordinate, x is the coordinate for obtaining the modeling value, and K is the variance coefficient of the function, and the coordinate calculation method of the differential touch sensing system. The method of claim 10,
The displacement is

Δ _x is the displacement of the x coordinate, w _x , w _x-1 and w _{x + 1} are the accumulated values for the touch differential values for each coordinate, and n _x , n _x-1 and n _{x + 1} are Coordinate calculation method of the differential touch sensing system, which is the average noise value for each coordinate. The method of claim 10,
The displacement is

Is set to, S1 is

Corresponding to a preset approximation value, the S2 is

Corresponding to a preset approximation, δ _x is the displacement of the x coordinate, w _x , w _x-1 and w _{x + 1} are accumulation values for touch differential values for each coordinate, n _x , n _x-1 and n _{x + 1} is a coordinate calculation method of the differential touch sensing system, which is the average noise value for each coordinate.

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