KR101549213B1 - Apparatus for detecting touch points in touch screen and method thereof - Google Patents

Abstract

The present invention discloses an apparatus for detecting a touch point on a touch screen and a method thereof. The apparatus for detecting a touch point according to the present invention includes: a touch region selection unit which selects a region satisfying a preset standard as a candidate touch region from a generated image based on a sensing value output from a touch screen sensor; a touch coordinate calculation unit which calculates coordinates of a touch point from the selected candidate touch region; and a touch coordinate correction unit which compares the calculated coordinates of the touch point with previous coordinates of the touch point and corrects the calculated coordinates of the touch point according to the comparison result.

Description

[0001] APPARATUS FOR DETECTING TOUCH POINTS IN TOUCH SCREEN AND METHOD THEREOF [0002]

The present invention relates to a touch screen, and more particularly, to an apparatus and method for detecting a touch point on a touch screen.

Touch input technology is an advanced method of inputting information to a computer and a digital device by touching a hand or a pen directly on the display so that it can be intuitively and conveniently used in a manner of inputting with a conventional button, . The touch screen based on user convenience is expanding its application scope mainly to electronic devices such as cash dispensers, navigation and mobile phones. Especially, as the mobile market has rapidly expanded from smart phones, Trend.

Demand for smartphones, which are the main demand for touch screens, is expected to increase, and demand for touch screens is expected to rise further due to the growth of tablet PCs due to launches of touch screen-enabled OSs. It is expected to be universally applied to all displays.

Capacitive touch panel, which is the current mainstream, has touch sensing and operation determined by controller IC, and pattern and film structure of ITO are changed according to controller IC. Therefore, capacitive touch panel market is changing from controller IC company to center have. Accordingly, there is a demand for a touch controller capable of stable and accurate coordinate recognition under various situations and various pointing devices. Therefore, even sophisticated tasks such as processing graphics data require the development of low-power controller implementations that are as accurate as possible, with minimal noise, fast response times, and low computational complexity.

Accordingly, an object of the present invention is to provide a method and apparatus for selecting a candidate touch region as an area satisfying a predetermined criterion, calculating coordinates of the touch point from the selected candidate touch region, The coordinates of which are compared with the coordinates of the previous touch point so as to correct the touch point on the touch screen.

However, the objects of the present invention are not limited to those mentioned above, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

According to another aspect of the present invention, there is provided an apparatus for detecting a touch point, the apparatus comprising: A touch region selecting section for selecting a region as a region; A touch coordinate calculation unit for calculating coordinates of a touch point from the selected candidate touch area; And a touch coordinate correction unit for comparing the coordinate of the calculated touch point with the coordinate of the previous touch point and for correcting the coordinate of the calculated touch point according to the comparison result.

Preferably, the touch region selection unit obtains a touch pixel satisfying a predetermined sensing value condition in the image, assigns an ID for each connection component indicating whether the touch pixel is connected according to a position between the touch pixels, The candidate touch region is selected based on the ID for each connection component.

Preferably, the touch region selection unit detects a local maximum value in the selected candidate touch region and measures a distance between the pixel having the local maximum value and the other pixels in the candidate touch region, And the ID for each connection component is re-assigned to all the pixels in the candidate touch region based on the connection component ID.

Preferably, the touch coordinate calculator calculates the sum of the basic values of the basic sets of the basic sets including the touch pixels having the same connection component ID and the adjacent pixels, and divides the sum of the basic sets by the number of the reference pixels. And when the number exceeds the numerical value, the coordinate of the touch point is calculated based on the sum of the basic values for each pixel in the horizontal or vertical direction and the weighted sum of the default value and the coordinates.

Preferably, the touch coordinate calculator calculates a sum of a basic value for each pixel of a touch pixel having the same connection component ID and a basic set including adjacent pixels, and divides the sum of the obtained basic set by the number of reference pixels And determines the candidate touch area as noise when the predetermined value is not exceeded.

Preferably, when the distance between the current touch point and the previous touch point is less than a predetermined size, the touch coordinate correction unit assigns the ID of the previous touch point to the ID of the current touch point, The coordinate of the current touch point is corrected using a weighted sum of the coordinate values corresponding to the previous touch point and the current touch point.

According to another aspect of the present invention, there is provided an apparatus for detecting a touch point, comprising: a preprocessor for receiving a sensing value output from the touch screen sensor and generating an image based on the sensed input value and applying a preprocessing process to the generated image; And further comprising:

According to another aspect of the present invention, there is provided a method of detecting a touch point, the method comprising: a touch region selection step of selecting a region that satisfies a predetermined criterion as a candidate touch region from an image generated based on a sensing value output from the touch screen sensor; A touch coordinate calculation step of calculating coordinates of a touch point from the selected candidate touch area; And a touch coordinates correcting step of comparing the coordinates of the calculated touch point with the coordinates of the previous touch point and correcting the coordinates of the calculated touch point according to the comparison result.

Accordingly, the present invention selects a region that satisfies a predetermined criterion as a candidate touch region, calculates coordinates of the touch point from the selected candidate touch region, compares the coordinates of the calculated touch point with the coordinates of the previous touch point, So that it is possible to extract coordinates that are robust against noise even in a noise generation situation.

Further, the present invention has the effect of clearly recognizing individual touches even in two or more multi-touch situations.

Further, since the coordinates of the touch point can be extracted through a low calculation amount, the present invention can realize a fast response speed and a low power system.

1 is a block diagram illustrating an apparatus for detecting a touch point according to an exemplary embodiment of the present invention.
2 is a view showing an image of a sensing value measured by a touch screen sensor.
3A and 3B are diagrams showing noise patterns and noise removal results.
FIGS. 4A and 4B are diagrams showing noise removal results and connection component calculation results. FIG.
5 is a diagram for explaining the principle of detecting a local maximum value.
6 is a diagram for explaining a touch separation process based on a local maximum value.
7 is a diagram for explaining the principle of calculating coordinates of a touch point.
FIG. 8 is a diagram showing trend lines and corrected coordinates through linear and quadratic regression analysis. FIG.
9 is a diagram illustrating a method for detecting a touch point according to an embodiment of the present invention.

Hereinafter, an apparatus and method for detecting a touch point on a touch screen according to an embodiment of the present invention will be described with reference to the accompanying drawings. The present invention will be described in detail with reference to the portions necessary for understanding the operation and operation according to the present invention.

In describing the constituent elements of the present invention, the same reference numerals may be given to constituent elements having the same name, and the same reference numerals may be given thereto even though they are different from each other. However, even in such a case, it does not mean that the corresponding component has different functions according to the embodiment, or does not mean that it has the same function in different embodiments, and the function of each component is different from that of the corresponding embodiment Based on the description of each component in FIG.

Particularly, in the present invention, an area satisfying a preset reference is selected as a candidate touch area, the coordinates of the touch point are calculated from the selected candidate touch area, and the coordinates of the calculated touch point are compared with those of the previous touch point And suggests new ways to do this.

1 is a block diagram illustrating an apparatus for detecting a touch point according to an exemplary embodiment of the present invention.

1, an apparatus for detecting a touch point according to the present invention includes an input unit 110, a preprocessor 120, a touch region selection unit 130, a touch coordinate calculation unit 140, A display unit 150, an output unit 160, and the like.

The input unit 110 may receive a sensing value measured by a touch screen sensor.

2 is a view showing an image of a sensing value measured by a touch screen sensor.

Referring to FIG. 2, the touch screen sensor includes a first sensor Tx for sensing an x-axis direction and a second sensor Rx for sensing a Y-axis direction. The sensing value can be obtained and the sensing value can be generated as an image (raw data).

At this time, the sensing value per pixel is 8 bits and ranges from 0 to 255. [ The portion that is touched has a larger value. The touched point appears as a bright color in the lower left corner of the image.

The preprocessing unit 120 may apply a pre-processing to the generated image.

3A and 3B are diagrams showing noise patterns and noise removal results.

Referring to FIG. 3A, since noise in the form of a lattice occurs due to the difference between the offsets of the first sensor and the second sensor, pixels in the same row and column have similar values.

Referring to FIG. 3B, a predetermined pre-processing process is applied to an input image in order to minimize the noise of the lattice pattern and amplify the value of the touch point.

In particular, the preprocessing unit 120 according to the present invention may perform a preprocessing process based on the average value of the pixels in the image generated by the sensing values measured from the first sensor and the second sensor.

은 각 지점의 값을 P(m,n)이라고 가정할 때 다음의 [수학식 1]과 같이 구할 수 있다.When calculating the average value, a method of sampling only in odd-numbered pixels is used for fast calculation. Value after preprocessing

Can be obtained as shown in the following equation (1), assuming that the value of each point is P (m, n).

[Equation 1]

where m = 1, 2, ..., 15, n = 1, 2, ..., 27

는 모든 지점의 평균값을 나타낸다. 상기 식들은 센서 화소수가 15 x 27임을 가정한 것으로 터치스크린의 화소 수가 변하면 해당 수치가 변경되야함은 물론이다.Here, Tx _n is the average value of the n-th Tx channel, Rx _m is the average value of the m-th Rx channel,

Represents the average value of all points. It is needless to say that the above formula assumes that the sensor pixel number is 15 x 27, and the corresponding value should be changed when the number of pixels of the touch screen changes.

The average value of all points is used to equalize the overall brightness and is utilized for adaptive thresholding in the touch region selection step. Also, by performing an integer operation without performing a floating point operation, the operation speed can be improved.

The touch region selection unit 130 may select a region that satisfies predetermined criteria from the minimized image through a preprocessing process as a candidate touch region.

FIGS. 4A and 4B are diagrams showing noise removal results and connection component calculation results. FIG.

4A and 4B, the connected component is composed of a touch pixel having a higher value than the surrounding area and an adjacent touch pixel connected to the touch pixel, as shown in FIG. 4B. The position T (m, n) of the touch pixel of the frame passing through the frame is calculated as shown in the following equation (2).

&Quot; (2) "

According to Equation (2), when T (m, n) is 1, it indicates that the pixel is a touch pixel. This calculation process can be included in the above-mentioned preprocessing process, so that efficient calculation is possible. Of course, the threshold value 13 can be changed when the hardware characteristics are changed.

을 터치지점정보로 저장한다.Based on the position of the touch pixel, the values (m, n) of the Tx and Rx channels of the touch pixel and the preprocess value

As touch point information.

Since the touch pixel is sequentially calculated for each Tx or Rx, the connection component is calculated through only one calculation by checking whether the previous Tx or Rx is a touch pixel.

To do this, it is necessary to assign an ID for each link component. The basic algorithm is as follows.

1. Initialize the global ID to zero.

2. Check pixels of all lines sequentially. If the current pixel is a touch pixel then:

a. If the previous pixel is a touch pixel, the ID of the current pixel is made equal to the ID of the previous pixel.

b. Otherwise, use the value of global ID plus 1 as your ID.

3. Increase the global ID by 1 each time a new line starts.

4. If the current pixel is a touch pixel and there is a touch pixel with a different ID on the previous line, replace all touch pixels of that ID with the ID of the current pixel.

The connection component is calculated using the ID assignment method for each connection component. Thus, the region detected as a connected component is regarded as the candidate touch region.

In this case, when the size of the connection component is large, it is generally considered that two or more touches are likely to occur. For accurate calculation of the touch coordinates, not only the touch pixel but also the pixel values not classified as the left, right, top, bottom four touch pixels around the touch pixel should be calculated. Since the centroid calculation after the separation is complicated by the general centroid calculation method, the present invention uses the local centroid calculation method. As described above, in the present invention, it is possible to reduce the execution time of the entire algorithm by facilitating the centroid calculation through the calculation of the local centroid.

To do this, it is necessary to determine which of the peripheral pixels of each touch pixel is included in the centroid calculation of each touch pixel. In this case, all the pixels to be included in the centroid calculation are referred to as reference pixels. The touch pixel is also included in the reference pixel.

The reference pixel is determined according to the distribution of the surrounding touch pixels. The algorithm is as follows.

1. Inspect all the touch pixels registered in touch point information in order.

2. At first, assume that four points of the left, right, top, and bottom of the touch pixel are reference pixels. Inspect 8 pixels around the touch pixel and determine if there is a touch pixel.

If there is a touch pixel, do the following:

a. If the touch pixel is located left, right, up, or down, remove the reference pixel at that position.

b. If there is a touch pixel on the upper left of the touch pixel, the reference pixel on the left when there is a touch pixel, if there is a touch pixel on the upper left, a reference pixel on the upper right, and a touch pixel on the lower right In this case, remove the right reference pixel. This allows calculation of the local centroid value per pixel and calculation of the centroid of the candidate touch region without reference pixels that are used redundantly in the candidate touch region.

3. Calculate the local centroid using a specific touch pixel and its associated reference pixel, but calculate only the values required for the centroid calculation and do not calculate the final touch position coordinates.

a. Calculate the default value for centroid calculation as follows.

b. In the Tx direction, the sum of the left and right reference pixels and the current touch pixel is obtained. It also stores the sum of the default values multiplied by the Tx coordinate values.

c. In the Rx direction, the sum of the upper and lower reference pixels and the current touch pixel is obtained. It also stores the sum of the default values multiplied by the Rx coordinate values.

d. Stores the number of all pixels referenced in the current touch pixel.

The calculated result is stored as centroid information and used in subsequent calculations.

Since the detected candidate touch area regards the connected component as one touch based on whether or not the candidate touch area is connected, two or more adjacent touches can be recognized as one touch. In this case, each touch point of the multi-touch recognized as one touch area can be separated through a touch separation process. To this end, in the present invention, a local maximum value is detected in a touch region detected as a connected component, and the detected pixel of the local maximum value is regarded as a touch point.

5 is a diagram for explaining the principle of detecting a local maximum value.

Referring to FIG. 5, the local maximum value detection is a method of detecting eight pixels in the vicinity and detecting a local maximum pixel when the center pixel has a maximum value as a result of the examination.

A new touch ID can be assigned to the pixel having the local maximum value and separated.

6 is a diagram for explaining a touch separation process based on a local maximum value.

Referring to FIG. 6, there are two local maxima in the region having the same ID in the touch point information (upper left, lower right). And assigns different IDs to two touch pixels having a local maximum value. The distance between the touch pixel having the local maximum value and the remaining touch pixel is measured and the ID of the local maximum pixel at the minimum distance is given as the ID of the remaining touch pixel. The remaining touch pixels in the middle area are removed in the following manner. The touch pixel in the middle area may mean a pixel having a difference between a maximum distance and a minimum distance from a touch pixel having a local maximum value of 1 or less and a maximum distance of 2 or less.

However, in the multi-touch point situation, when the touch point does not exist at the local maximum value, the touch separation may not be performed properly. In order to take this into consideration, if the number of detected touch points of the current frame is smaller than the number of detected touch points of the previous frame, an additional touch separation process is performed.

In this case, since the size of the touch area detected when touching with a finger is within 2 to 3 pixels in width and height, it is possible to separate 4 or more connected components such that the width and height are less than 2 Give a new ID. Needless to say, in case of a touch screen having a different sensor size, the horizontal / vertical threshold value can be changed.

The touch coordinate calculation unit 140 can calculate the coordinates of the touch point from the selected candidate touch area. The coordinate calculation of the touch point is to estimate the actual touch position from the touch pixels.

7 is a diagram for explaining the principle of calculating coordinates of a touch point.

As shown in FIG. 7, white pixels represent touch pixels, and blue points represent actual touch points. In the present invention, TCoG (Thresholded center of gravity), which is a type of centroid, is used to calculate coordinates of a touch point. That is, centroid is obtained by using a limit value of a certain threshold value rather than the pixel value itself in the coordinate calculation of the touch point.

First, a set p of pixels satisfying a preset condition for a connected component T _k (m, n) having an ID k is obtained as shown in the following equation (3).

&Quot; (3) "

This is a case of a general connection element, and if a separation process is performed, a plurality of touch points are detected by dividing p. This is described above. The basic value D (m, n) of each pixel is obtained as shown in the following equation (4) for the obtained pixel set.

&Quot; (4) "

으로 지정되었으며,

<I_T인 경우 D(m,n)이 음수가 되어 오류가 발생할 수 있으므로 D(m,n)은 항상 0 이상의 값을 갖도록 보정한다. 이렇게 계산한 값을 다음의 [수학식 5]에 대입함으로써, 임의의 연결 요소 TCoG (m_c,n_c)를 구한다.here,

And,

If <I _T , D (m, n) is negative and error may occur, so D (m, n) is always corrected to have a value greater than or equal to zero. By substituting the thus calculated value to the following Equation 5] is obtained to any of the connection elements TCoG (m _c, n _c).

&Quot; (5) &quot;

For faster and more precise calculation, the present invention uses a method of subdividing the pixel set p into Tx and Rx directions. A Tx direction of the p p _m and _n Rx direction is overridden by [Equation 6].

&Quot; (6) &quot;

The TCoG (m _c , n _c ) modified according to Equation (6) above is redefined as Equation (7).

&Quot; (7) &quot;

In order to easily perform this modified TCoG calculation, the noise removal is performed together with the coordinate calculation of the final touch point with the reset ID based on the calculation result of the local centroid and the separation result as described above. The overall algorithm is as follows.

1. Calculate the next value using touch pixels with the same ID.

The value obtained by dividing the total number of pixels by the total number of pixels is defined as an average default value. If the value does not exceed a certain value, it is judged as noise.

a. When the total number of reference pixels in one frame is 8 or more, if the average default value does not exceed 5, it is judged as noise.

b. If the total number of reference pixels is less than 8, if the average default value does not exceed 3, the touch pixel at the position (m, n) is determined as noise.

2. For touch pixels with IDs not judged as noise, do the following.

,

)을 구한다.a. The sum of the default values for Tx and Rx (

,

).

,

) 을 구한다.b. The sum of the weights for Tx and Rx, i.e., the sum of the base value and the coordinate value (

,

).

c. When the sum of the weights by Tx and Rx is divided by the sum of the default values, the coordinates in the Tx-Rx coordinate system are extracted and converted into a corresponding pixel coordinate system, for example, a 600x1024 pixel coordinate system.

Through this process, the coordinates of the touch point can be calculated primarily in the present invention.

The touch coordinate correcting unit 150 can correct the coordinates of the calculated touch points by comparing them with the coordinates of the previous touch points. At this time, the touch coordinate correcting unit 150 compares the coordinates of the calculated current touch point with the coordinates of the previous touch point, and gives the ID of the current touch point according to the comparison result. The ID of the current touch point has the ID of the previous touch point when the predetermined size, for example, the square of the distance is 0.8 or less.

The touch coordinate correcting unit 150 can correct the coordinates of the current touch point using the weighted sum of the coordinates of the previous touch point having the same ID and the coordinates of the current touch point as a result of assigning the ID rules.

At this time, if the present touch point is close to a predetermined size, for example, a distance of a distance of 0.01 or less from the previous touch point, the touch coordinate correcting unit 150 corrects the previous touch The coordinates of the point can be corrected to have the same value.

Also, in the present invention, correction is performed through regression analysis such as linear regression analysis and secondary regression analysis so that the progress of the touch can be smoothly connected linearly.

When the current ID of the current touch point exists in succession to five previous frames, the trend line of the five previous touch points is obtained to calculate the correction coordinates.

The linear regression equation and the second regression equation are expressed by the following equations (8) and (9).

&Quot; (8) &quot;

Y = aX + b

&Quot; (9) &quot;

Y = aX ² + bX + c

The variables a and b can be calculated using the linear simultaneous equations in the equations (8) and (9).

The variables a and b can be calculated using the linear simultaneous equations in the equations (8) and (9).

FIG. 8 is a diagram showing trend lines and corrected coordinates through linear and quadratic regression analysis. FIG.

As shown in FIG. 8, in order to minimize the extrapolation error, the trend correction coordinates are reflected only when the distance between the trend correction coordinates and the trend correction priorities is 0.03 or less. In terms of execution time and linearity, linear regression analysis shows better performance than quadratic regression.

Accordingly, in the present invention, coordinates of a touch point are corrected using linear regression analysis.

The output unit 160 may output touch information including coordinates, ID, and the like of the corrected touch point.

9 is a diagram illustrating a method for detecting a touch point according to an embodiment of the present invention.

As shown in FIG. 9, an apparatus for detecting a touch point according to the present invention (hereinafter referred to as a touch point detection apparatus) can receive a sensing value output from a touch screen sensor (S910).

Next, the touch point detection apparatus generates an image based on the received sensing value, and applies a pre-processing to the generated image (S920).

Next, in step S930, the touch point detection apparatus may select a region that satisfies predetermined criteria from the image with the minimum noise through a preprocessing process, as a candidate touch region.

At this time, the touch point detection device obtains a touch pixel having a predetermined sensing value in the image, assigns an ID for each connection component indicating whether or not the touch pixel is connected according to a position between the touch pixels, Area.

Next, the touch point detection apparatus can calculate coordinates of the touch point from the selected candidate touch area (S940).

At this time, the touch point detection device obtains the sum of the basic values of the basic pixels of the basic pixel including the touch pixels having the same connection component ID and adjacent pixels, and divides the sum of the obtained basic sets by the number of the reference pixels, The coordinates of the touch point are calculated based on the sum of the basic values for each pixel in the horizontal or vertical direction and the weighted sum of the basic value and the coordinates.

Next, the touch point detection device compares the coordinates of the calculated touch point with the coordinates of the previous touch point, and corrects coordinates of the current touch point according to the comparison result (S950).

At this time, when the distance between the current touch point and the previous touch point is less than a predetermined size, the touch point detection apparatus grants the ID of the previous touch point to the current touch point ID, The coordinates of the current touch point are corrected using the weighted sum of the coordinates corresponding to the current touch point.

Next, the touch point detection apparatus can output the coordinates of the corrected touch point (S960).

It is to be understood that the present invention is not limited to these embodiments, and all of the elements constituting the embodiments of the present invention described above may be combined or operated in one operation. That is, within the scope of the present invention, all of the components may be selectively coupled to one or more of them. In addition, although all of the components may be implemented as one independent hardware, some or all of the components may be selectively combined to perform a part or all of the functions in one or a plurality of hardware. As shown in FIG. In addition, such a computer program may be stored in a computer-readable medium such as a USB memory, a CD disk, a flash memory, etc., and read and executed by a computer, thereby implementing embodiments of the present invention. As the storage medium of the computer program, a magnetic recording medium, an optical recording medium, a carrier wave medium, or the like may be included.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or essential characteristics thereof. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

110: input unit
120:
130: Touch region selection unit
140: Touch coordinate calculation unit
150: Touch coordinate correction unit
160: Output section

Claims (14)

A touch region selecting unit for selecting a region that satisfies a predetermined criterion as a candidate touch region from an image generated based on a sensing value output from the touch screen sensor;
A touch coordinate calculation unit for calculating coordinates of a touch point from the selected candidate touch area; And
A touch coordinate correction unit for comparing coordinates of the calculated touch point with coordinates of a previous touch point and for correcting the coordinates of the calculated touch point according to the comparison result;
Wherein the touch region selection unit comprises:
Obtaining a touch pixel satisfying a predetermined sensing value condition in the image, assigning an ID for each connection component indicating whether or not the touch pixel is connected according to a position of the touch pixel,
And when the assignment of the ID for each connection component is completed, the candidate touch region is selected based on the ID for each connection component. delete The method according to claim 1,
Wherein the touch region selection unit comprises:
Detecting a local maximum value in the selected candidate touch area and measuring a distance between the pixel having the local maximum value and the other pixels in the candidate touch area,
And re-assigns the ID for each connection component to all pixels in the candidate touch region based on the measured distance. The method according to claim 1,
The touch coordinate calculator calculates,
Obtains a sum of basic values of a basic set including touch pixels having the same connection component ID,
And calculating the coordinates of the touch point based on the sum of the basic values for each pixel in the horizontal or vertical direction and the weighted sum of the basic value and the coordinates when the sum of the obtained basic sets is divided by the number of the reference pixels and exceeds a predetermined value Wherein the touch point detecting means detects the touch point. The method according to claim 1,
The touch coordinate calculator calculates,
Obtains a sum of basic values of a basic set including touch pixels having the same connection component ID,
And determining the noise as a result of dividing the sum of the obtained basic sets by the number of pixels referenced and not exceeding a predetermined value. The method according to claim 1,
The touch coordinate correcting unit,
Assigns the ID of the previous touch point to the ID of the current touch point when the distance between the current touch point and the previous touch point is less than a predetermined size,
Wherein the coordinates of the current touch point are corrected using a weighted sum of a previous touch point having the same ID and a coordinate value corresponding to the current touch point as a result of applying the ID. The method according to claim 1,
A preprocessor for receiving a sensing value output from the touch screen sensor and generating an image based on the sensed input value and applying a preprocessing process to the generated image;
Wherein the touch point detecting unit detects the touch point. A touch region selection step of selecting a region that satisfies a predetermined criterion as a candidate touch region from an image generated based on a sensing value output from the touch screen sensor;
A touch coordinate calculation step of calculating coordinates of a touch point from the selected candidate touch area; And
A touch coordinates correction step of comparing coordinates of the calculated touch point with coordinates of a previous touch point and correcting the coordinates of the calculated touch point according to the comparison result;
Wherein the touch region selection step comprises:
Obtaining a touch pixel satisfying a predetermined sensing value condition in the image, assigning an ID for each connection component indicating whether or not the touch pixel is connected according to a position of the touch pixel,
And selecting the candidate touch region based on the ID for each connection component when the assignment of the ID for each connection component is completed. delete 9. The method of claim 8,
The touch region selection step may include:
Detecting a local maximum value in the selected candidate touch area and measuring a distance between the pixel having the local maximum value and the other pixels in the candidate touch area,
And re-assigning the connection component ID to all pixels in the candidate touch region based on the measured distance. 9. The method of claim 8,
Wherein the touch coordinate calculation step comprises:
Obtains a sum of basic values of a basic set including touch pixels having the same connection component ID,
And calculating the coordinates of the touch point based on the sum of the basic values for each pixel in the horizontal or vertical direction and the weighted sum of the basic value and the coordinates when the sum of the obtained basic sets is divided by the number of the reference pixels and exceeds a predetermined value The method comprising the steps of: 9. The method of claim 8,
Wherein the touch coordinate calculation step comprises:
Obtains a sum of basic values of a basic set including touch pixels having the same connection component ID,
And judging the noise as a result of dividing the sum of the obtained basic sets by the number of pixels referenced and not exceeding a predetermined value. 9. The method of claim 8,
Wherein the touch coordinates correction step comprises:
Assigns the ID of the previous touch point to the ID of the current touch point when the distance between the current touch point and the previous touch point is less than a predetermined size,
Wherein the coordinate of the current touch point is corrected using a weighted sum of a previous touch point having the same ID and a coordinate value corresponding to the current touch point as a result of applying the ID. 9. The method of claim 8,
A preprocessor for receiving a sensing value output from the touch screen sensor and generating an image based on the sensed input value and applying a preprocessing process to the generated image;
The method further comprising the step of:

Images