KR101764728B1

KR101764728B1 - Method for recovering location of multi-touch on touch screen based on differential sensing

Info

Publication number: KR101764728B1
Application number: KR1020160010760A
Authority: KR
Inventors: 김형원; 김지호; 최경섭; 모하메드 가말 아흐메드 모하메드
Original assignee: 충북대학교 산학협력단
Priority date: 2016-01-28
Filing date: 2016-01-28
Publication date: 2017-08-04

Abstract

A method and apparatus for recovering the location of multi-touch on a touch screen based on differential sensing is disclosed. The method for recovering the location of multi-touch on a touch screen based on differential sensing includes a step of receiving input information based on a users touch through a touch screen, a step of applying a driving signal to each of x TX lines (x is a natural number) on the touch screen, and calculating a differential sensing value for each of y RX lines (y is a natural number) located on the touch screen based on the driving signal, and a step of restoring the position of the touch by restoring touch panel data due to the input information based on the differential sensing value.

Description

TECHNICAL FIELD [0001] The present invention relates to a multi-touch position restoration method,

The present invention relates to a multi-touch sensing method and apparatus system, and more particularly, to a multi-touch position restoring method and apparatus system of a differential sensing based touch screen.

With the increasing use of touch screens, products with touch screens have been used in recent years. In the case of a mutual capacitance type touch screen, a method of detecting a change in capacitance is widely used, and there are various types of capacitive touch screens. It can be largely divided into a surface capacitive touch screen and a projected capacitive touch screen. Projected capacitive touch screen panels can be divided into a mutual capacitance type and a self-capacitance touch It can be further divided into screens. Among them, mutual capacitive touch screen supports high resolution and multi-touch function, and is mainly used in small and medium sized mobile products.

In general, a mutual capacitance type touch screen can detect a touched position by measuring changes in noise and capacitance. Such capacitive touch screens are often influenced by the noise measured values, which sometimes cause erroneous detection of the touched position during the actual touch and cause the accuracy to deteriorate. And the signal to noise ratio (SNR) is small due to the generated noise.

The noise generated by the touch screen panel is usually divided into random noise and periodic noise. Random noise on the touch screen panel is display noise and ambient electromagnetic waves, and periodic noise is mainly caused by fluorescent noise and battery charge noise. Further, in the touch screen panel method, when the touched position affects the two adjacent driving lines and the sensing line, there is a problem that the touched position can not be known.

KR 10-2009-0111027

One aspect of the present invention provides a method for restoring a multi-touch position of a differential-based touch screen.

Another aspect of the present invention provides a multi-touch location restoration device system of a differential sensing based touch screen.

According to an aspect of the present invention, there is provided a method of restoring a multitouch position of a touch screen based on differential sensing, the method comprising: receiving input information based on a touch of a user through the touch screen; Calculating a differential sensing value for each of y (where, y is a natural number) RX lines located on the touch screen, based on the driving signal, calculating a differential sensing value based on the driving signal, And restoring the position of the touch by restoring the touch panel data due to the input information based on the input information.

Wherein the y RX lines comprise a first RX line and a second RX line adjacent to the right of the first RX line and wherein a first differential sensing value of the first RX line of the differential sensing value is greater than a first differential sensing value of the first RX line, Wherein the first touch panel value of the RX line is a difference value of a second touch panel value of the second RX line and the y RX line further comprises a third RX line where the RX line adjacent to the right side is not positioned, The second differential sensing value of the third RX line of the differential sensing value is a difference value of a virtual touch panel value of a virtual RX line at a third touch panel value of the third RX line, .

The step of restoring the touch panel data by restoring the touch panel data due to the input information based on the differential sensing value may include generating a restoration value for each of the y RX lines, And restoring the position corresponding to the restored value to the position of the touch.

Also, the restored values for each of the y RX lines are restored based on the following equation

&Lt; Equation &

Here, N _TX is the number of the TX line, N _RX is the number of the RX line, Recovery (i, j) is the restored value of the position (i, j) on the touch screen, the TSP (i, j) is (i, j) is a touch panel value at a position (i, j), TSP (i, j + Lt; / RTI >

According to another aspect of the present invention, there is provided a touch screen system for restoring a multitouch position of a differential touch screen, comprising: a touch panel implemented to receive input information based on a touch of a user; And a differential sensing circuit for calculating a differential sensing value for each of the y (where, y is a natural number) RX lines located on the touch screen based on the driving signal on the basis of the driving signal, And a touch image restoring unit for restoring the touch position by restoring the touch panel data due to the input information based on the differential sensing value.

The image reconstructing unit may be configured to generate a reconstruction value for each of the y RX lines and to restore a position corresponding to a reconstruction value that is equal to or greater than a threshold value among the reconstruction values to the position of the touch.

&Lt; Equation &

The multi-touch position restoration method and apparatus system of the differential sensing based touch screen according to the embodiment of the present invention can improve the touch sensing accuracy by accurately restoring the touch point with high sensitivity compared to the conventional technique. Therefore, not only the performance improvement of the small and medium sized touch screen but also the touch sensing processing and the touch performance of the large touch screen can be improved and the multi touch processing is also strong.

1 is a conceptual diagram illustrating a system structure of a general differential sensing method for a large touch screen controller.
2 is a conceptual diagram illustrating a differential sensing based touch screen according to an embodiment of the present invention.
3 is a conceptual diagram illustrating restoration of a touch point according to an embodiment of the present invention.
4 is a conceptual view illustrating a method of restoring a touch position in a touch screen according to an embodiment of the present invention.
5 is a flowchart illustrating a multi-touch restoration operation according to an embodiment of the present invention.
6 is a conceptual diagram illustrating a touch screen system according to an embodiment of the present invention.
7 is a flowchart illustrating a multi-touch position restoration method of a differential-sensing-based touch screen according to an exemplary embodiment of the present invention.

The following detailed description of the invention refers to the accompanying drawings, which illustrate, by way of illustration, specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention. It should be understood that the various embodiments of the present invention are different, but need not be mutually exclusive. For example, certain features, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the invention in connection with an embodiment. It is also to be understood that the position or arrangement of the individual components within each disclosed embodiment may be varied without departing from the spirit and scope of the invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is to be limited only by the appended claims, along with the full scope of equivalents to which such claims are entitled, if properly explained. In the drawings, like reference numerals refer to the same or similar functions throughout the several views.

Hereinafter, preferred embodiments of the present invention will be described in more detail with reference to the drawings.

Recently, as the utilization of the touch screen has increased, the size of the screen for the product has also been diversified. Among them, there is a problem that a plurality of controller chips must be used in order to satisfy the required number of channels by applying a technique of processing touch detection of a small touch screen to a large touch screen such as an educational electronic board and a medical monitor. In addition, there is a problem in achieving a high touch resolution due to a decrease in touch sensitivity due to noise and a high line resistance component generated in a large LCD (liquid crystal display).

A single line sensing method can be used to handle the touch sensing of a small touch screen. The single line sensing technique is simple to implement and has a simple advantage of the touch location decision algorithm. On the other hand, the lack of noise elimination capability makes touch detection and processing speed considerably low when applied to a large touch screen. Therefore, in recent touch screens, a differential sensing method that can increase the processing speed by increasing noise removal and sensing speed is more and more being used.

1 is a conceptual diagram illustrating a system structure of a general differential sensing method for a large touch screen controller.

A square wave or sinusoidal wave can be sequentially applied to the TX line of the touch screen panel through the TX signal driving circuit 100. [ The differential detection circuit unit 120 may sense the output waveforms from two RX lines (receive lines) spaced apart from the lower surface of the panel by differential detection, and the differential charge amount may be converted to a voltage.

At this time, if the two RX lines have different values, the output of the comparator 140 is 1. If the two RX lines have the same value, the output of the comparator 140 becomes zero. Thus, the presence or absence of a touch can be determined with the output of the comparator 140. However, the problem of the conventional differential sensing method is that when the two RX lines are touched points, the output value becomes 0, which is not distinguishable from the case where the two RX lines are not touched. Therefore, there is a need for a new technique for improving the touch sensing performance because the accuracy of the presence or absence of touch is lowered.

Hereinafter, a method and an apparatus for restoring a multi-touch position of a differential-based touch screen according to an exemplary embodiment of the present invention can be applied to a method of detecting a multi-touch position without being affected by noise in a mutual capacitive touch screen have.

In the multi-touch position restoration method and apparatus of the differential-sensing-based touch screen according to the embodiment of the present invention, differential arithmetic operations are performed on RX lines adjacent to each other rather than a predetermined distance, and an initial value based sequential accumulation algorithm To determine whether or not a touch is made. In this way, the accuracy of touch detection can be improved and this method can be applied to mid-sized touch screen and high-resolution small touch screen.

2 is a conceptual diagram illustrating a differential sensing based touch screen according to an embodiment of the present invention.

Referring to FIG. 2, the TX signal driving circuit 200 sequentially applies a square wave or a sinusoidal wave to the TX line on the left side of the touch panel and sequentially turns on a pair of adjacent RX lines entering the lower differential sensing circuit 220 Signal to the differential detection circuit 220. The differential sensing circuit 220 may sense a difference value for the sensing signal of each RX line. The differential sensing results may be muxed and converted by an analog to digital converter (ADC) 240 and stored in memory 260.

The differential sensing circuit 220 can perform differential operation on the sensed data of two RX lines. The differential operation results may be stored in memory 260 one after the other. The result of the differential operation stored in the memory 260 may be restored by the touch image restoring unit 280 and used for restoring (determining) the touch position.

Hereinafter, in FIG. 3, the result of the differential calculation according to the touch of the touch point by the user and the restoration of the touch point are started.

3 is a conceptual diagram illustrating restoration of a touch point according to an embodiment of the present invention.

In FIG. 3A, the actual touch point of the touch screen represented by the coordinates is started. The portion indicated by the X on the touch screen may be the part touched by the user. For example, when the TX line is viewed as a row and the RX line is viewed as a column, the positions of (1, 1), (1, 2), (3, 3), (4, May be the portion that is touched by the user.

In Fig. 3 (B), values corresponding to the touched position and the non-touched position are started, respectively. It is assumed that the touched position has a value of 1 and the untouched position has a value of 0. [

In (C) of FIG. 3, the differential calculation result for the touch result of the user is started.

The result of the differential operation is the result of subtraction operation on the adjacent RX line.

When the touched position corresponds to 1 and it is assumed that the touched position corresponds to a non-touched 0, a differential operation result as shown in Fig. 3C can be generated.

For example, the differential calculation result value corresponding to the (1, 1) position may be 0 (= 1-1), which is the difference value between 1, which is the value of the (1, 1) . The differential operation result value corresponding to the (1, 2) position may be 1 (= 1-0), which is the difference value between 1, which is the value of (1, 2), and 0, which is the value of (1, 3).

For another example, the result of the differential operation corresponding to the (4, 2) position is -1 (= 0-1), which is the difference between 0, which is the value of (4, 2) . The differential calculation result value corresponding to the position (4, 3) may be 0 (= 1-1), which is the difference value between 1, which is the value of the (4, 3) position and 1, which is the value of the (4, 4) The differential calculation result value corresponding to the position (4, 4) may be 1 (= 1-0), which is a difference value between 0, which is the value of the position (4, 4)

The coordinates corresponding to (x, 10) in the 10th column position can be assumed to be 11 columns virtually and the differential operation can be performed assuming that the value of the coordinates located in the 11th column is 0. [ For example, the coordinate value of (1, 10) may be 1 (= 1-0), which is a difference value between 1, which is the value of the position of (1, 10) and 0 which is the value of the position of (1, 11).

The multi-touch position restoration method and apparatus of the differential-sensing-based touch screen according to the embodiment of the present invention can restore the actual touch position by applying an initial value-based sequential accumulation technique from the results of the touch screen differential sensing circuit.

4 is a conceptual view illustrating a method of restoring a touch position in a touch screen according to an embodiment of the present invention.

In FIG. 4, detection for one RX line is initiated. Illustratively, a first RX line, a second RX line, a third RX line, a fourth RX line and a fifth RX line located on row A 400 are disclosed. (First RX line, column A), (second RX line, column A), (third RX line, column A), (fourth RX line, column A) The value (or touch panel data) may be a ₁ , a ₂ , a ₃ , a _4, and a ₅ .

In the B column 420, the differential operation data (or differential sensing result) is started. (First RX line, column A), (second RX line, column A), (third RX line, column A), (fourth RX line, column A) May be (a ₁ -a ₂ ), (a ₂ -a ₃ ), (a ₃ -a ₄ ), (a ₄ -a ₅ ), and (a ₅ ). (a ₅ ) may be a single sensing value of the fifth RX line, which is the last RX line, and this single sensing value may be used as an initial value in calculating the restored value.

The C column 440 starts the restoration result. In the restoration step, the initial value can be stored in the last row of column C, in addition to the next number in column B. In the restoration step, one row of the B column 420 and the C column 440 goes up one row and the result of adding the value of the next row of the B column 420 to the value of the current row of the C column 440 is added to the next row of the C column 440 You can repeat the action of saving to a row. Based on this operation, the algorithm can be completed by processing the values of all rows of column B 420 and repeating until all the restored values are generated in column C 440. The operation process of the multi-touch restoration technique of the present invention can be expressed as Equation 1 below.

&Quot; (1) "

&Quot; (2) "

In Equation (1), N _TX and N _RX denote the number of TX lines and RX lines. Recovery (i, j) are the restored values stored in column C as a result of the restoration algorithm operation.

Equation (2) is a differential detection result based on a differential operation and is a differential detection value (or a differential operation value) stored in the column B.

Referring to Equation (1), the result of the operation can be divided into two according to the row number j to be processed at present. If j points to the last RX line, the single line sensing value TSP (i, j) of the last row of the RX line can be loaded as is. Recovery (i, j) can be calculated by adding Diff (i, j), which is the differential operation result, and Recovery (i, j + 1), which is the recovery value calculated in the previous step, have.

5 is a flowchart illustrating a multi-touch restoration operation according to an embodiment of the present invention.

Referring to FIG. 5, after a drive signal is applied to the first TX line (i = 1), a pair of adjacent RX lines are sequentially operated to perform differential operation (step S500).

Specifically, a differential operation can be performed on the touch panel value (or data) (or the touch screen value (or data)) from the first RX line (j = 1). The first RX line may perform a differential operation with the second RX line. That is, after sensing the touch panel value TSP (i, j) of the n-th line and the touch panel value TSP (i, j + 1) of the (n + 1) (I, j) = TSP (i, j) - TSP (i, j) based on the touch panel value TSP (i, j) (i, j + 1)) can be calculated.

This operation can be performed up to the last column based on the judgment of j > N [RX (n)].

The differential operation values can be sequentially stored in a register. After sensing all of the RX lines corresponding to the first TX line, the last stored value in register 1 can be loaded and stored in register 2.

If the differential operation is performed up to the last column, a restoration procedure may be performed (step S520).

Specifically, when j indicates the last RX line, the single line sensing value TSP (i, j) of the last row of the RX line can be loaded as is as the initial value.

Thereafter, Diff (i, j), which is the result of the differential operation, is added to Recovery (i, j + 1), which is the restored value of the previous stage, while j is decremented by 1 (ie, for the RX line other than the last RX line) The value Recovery (i, j) can be calculated.

The restoration algorithm for all RX lines can be progressed while j is decreasing continuously until j becomes less than or equal to zero.

Thereafter, the restoration algorithm may be repeated up to the last TX line as the value of i (i.e., the value of the TX line) increases.

6 is a conceptual diagram illustrating a touch screen system according to an embodiment of the present invention

6 (A), an example of two touch screens sensed by a high resolution differential sensing touch screen sensing device with an 8-bit ADC is disclosed.

On the left side of FIG. 6A, one affected cell (touched cell) and eight affected cells located around one touched cell (touch point) are started.

On the right side of FIG. 6 (A), 18 affected cells 1 and 2 affected cells 2 located around two touched cells and two touched cells (touch points) / RTI >

The left side of FIG. 6 (B) starts restoring one touched cell (touch point) on the left side of FIG. 6 (A).

The right side of Fig. 6B starts restoring the two touched cells (touch points) on the right side of Fig. 6A.

Large negative values in column B indicate the state in which the first input line of the differential detector is touched, and large positive values indicate the state in which the second input line of the differential detector is touched. Small values near 0 or 0 indicate that both input lines are not touched or all are touched. High values above 90 in column C after the restoration is complete are the restoration results of the points actually touched. These values represent the Unknown value of the A row, which is the single line sensed values, and it can be seen that this corresponds to the position of the touch point in FIG. 6 (A). In column C, the median values between 20 and 80 represent weak touch values near the touch point, and low values near zero indicate non-touch points. Therefore, the present invention not only accurately discriminates the value and position of a strong single touch, multi-touch, but also provides a high sensitivity that can accurately discriminate weak touch values near the touch position.

7 is a flowchart illustrating a multi-touch position restoration method of a differential-sensing-based touch screen according to an exemplary embodiment of the present invention.

Referring to FIG. 7, input information based on a user's touch is inputted through a touch screen (step S700).

The user can touch the touch screen, and the touch signal of the user can be input according to the touch of the user.

And the differential sensing value is restored (step S710).

A driving signal is applied to each x TX line on the touch screen, where x is a natural number. Based on the driving signal, a differential sensing value for each y (where y is a natural number) RX lines located on the touch screen is Can be calculated.

Specifically, the y RX lines may include a first RX line and a second RX line adjacent to the right of the first RX line. The first differential sensing value of the first RX line among the differential sensing values may be a difference value between the first touch panel value of the first RX line and the second touch panel value of the second RX line.

The y RX lines may further include a third RX line where the right adjacent RX line is not located. The second differential sensing value of the third RX line of the differential sensing value may be the difference value of the virtual touch panel value of the virtual RX line at the third touch panel value of the third RX line and the virtual touch panel value may be zero .

Based on the differential sensing value, the touch panel data due to the input information is restored to restore the touch position (step S720).

The restoration of the position of the touch may generate restoration values for each of the y RX lines and may restore a position corresponding to the restored value that is equal to or greater than the threshold value among the restored values to the position of the touch. The restoration of the touch panel data can be performed based on the above-described equation.

Such a multi-touch position restoration method of the differential sensing based touch screen may be implemented in an application or implemented in the form of program instructions that can be executed through various computer components and recorded in a computer-readable recording medium. The computer-readable recording medium may include program commands, data files, data structures, and the like, alone or in combination.

The program instructions recorded on the computer-readable recording medium may be ones that are specially designed and configured for the present invention and are known and available to those skilled in the art of computer software.

Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks and magnetic tape, optical recording media such as CD-ROMs and DVDs, magneto-optical media such as floptical disks, media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like.

Examples of program instructions include machine language code such as those generated by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like. The hardware device may be configured to operate as one or more software modules for performing the processing according to the present invention, and vice versa.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention as defined in the appended claims. It will be possible.

Claims

A multi-touch position restoration method for a differential-based touch screen,
A driving signal is applied to each of the TX lines located on the touch screen, where i is a natural number, and a restoration is performed on each of the Rx lines j (where j is a natural number) located on the touch screen based on the driving signal. To obtain the value,
Is restored based on the following equation,
&Lt; Equation &

(Where N _TX is the number of TX lines, N _RX is the number of RX lines,
Recovery (i, j) is the restored value at position (i, j) on the touch screen,
The TSP (i, j) is the touch panel value at (i, j)
The TSP (i, j + 1) is a touch panel value at (i, j + 1)
Diff (i, j) is the differential sensing value at position (i, j)

The above-
A differential operation is performed on the touch panel value from the first RX line (j = 1) after applying the driving signal to the first TX line (i = 1) (I, j) = TSP (i, j) - TSP (i, j + 1) based on the sensed panel values TSP ), And this operation is performed up to the last column based on the judgment of j > N [RX (n)].
If the differential operation has been performed up to the last column, i. E. J is pointing to the last RX line, loading the single line sensing value TSP (i, j) of the last row of the RX line intact as is;
Recovery (i, j), which is a restoration value, is added by adding Diff (i, j), which is a result of differential operation with j decreasing by 1, to RX line not the last RX line, and Recovery (i, j + &Lt; / RTI >
The restoration algorithm for all RX lines proceeds continuously decreasing j until j becomes less than or equal to zero, and then the restoration algorithm repeats up to the last TX line, increasing the value of i, which is the value of the TX line Wherein the multi-touch position restoration method comprises:

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