KR20140104737A - Circuit and method for controling of differential touch sensing system - Google Patents

Abstract

A circuit for controlling a differential touch sensing system is disclosed. The control circuit includes: a labeling unit which performs a labeling process of converting a differential value into a labeling value; a palm region detecting unit which detects a palm region by scanning a change in the labeling value; a forgotten operation unit which performs forgotten operation including a first operation of setting a forgotten count value to unit blocks corresponding to the palm region, and a second operation, and a second operation of updating the forgotten count value of the unit blocks defined as an extended palm region in a previous frame in a region beyond the palm region; and a palm region extending unit which defines the unit blocks having the forgotten count value as the extended palm region.

Description

TECHNICAL FIELD [0001] The present invention relates to a control circuit for a differential touch sensing system,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a differential touch sensing system, and more particularly, to a control circuit and a control method of a differential touch sensing system for sensing a change of a palm area by a palm touch.

Recently, a display panel configured in a mobile device or the like has adopted a lot of touch functions.

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

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

The touch panel can be configured to perform touch recognition on an electrostatic basis. As an example of a touch panel that realizes electrostatic touch recognition, a "mutual capacitance touch sensing device" is disclosed in "US Patent Application US 2009/0091551" have.

A typical touch sensing system may be developed to sense in a differential manner in order to sense the corrected capacitance.

When the sensing signal is driven in a differential manner, the touch sensing system has a characteristic of being resistant to noise, so that the effect of improving the touch sensitivity and the sensing accuracy can be expected.

Recently, applications such as mobile devices are being developed to realize high performance. Accordingly, it is necessary to improve the function of the touch sensing system so as to correctly recognize the touch in order to support the high function.

A general touch sensing system is implemented to recognize a touch by a finger or a touch pen as a normal touch.

In the above-described touch recognition environment, the user can attempt to touch using a finger or a touch pen while the hand is in contact with the touch panel.

At this time, the palm area other than the touch area by the finger or the touch pen can be recognized as a touch. Here, the palm area means an area recognized by the palm or the side of the hand contacting the touch panel, and usually has a larger area than the touch area of the finger or the touch pen.

The palm area serves as an obstacle to recognition of a normal touch, and a recognition error of a normal touch may occur due to a palm area.

Therefore, the touch sensing system needs to distinguish the normal touch from the palm area.

In addition, the palm area can be reduced or enlarged according to the movement of the hand. If the palm area is reduced, the palm area may be mistaken for a normal touch.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a control circuit and a control method of a differential touch sensing system capable of accurately recognizing a normal touch area and a palm area.

It is another object of the present invention to provide a control circuit and method for a differential touch sensing system that can prevent misdirection of a reduced palm area as a normal touch in a process of changing the palm area according to the movement of a hand.

The control circuit of the differential touch sensing system according to the present invention includes a labeling unit that performs a labeling process of converting a differential value of a unit block of a sensed frame into a labeling value; A palm area detecting unit for detecting a palm area by scanning a change in the labeling value corresponding to each sensing line of the frame; A first operation for setting a forgetting count value to the unit blocks corresponding to the palm area and a second operation for updating the forgetting count value of the unit blocks defined as a palm area extended in a previous frame in an area outside the palm area A forgetting operation unit for performing a forgetting operation including two operations; And a palm area extension unit for defining the unit blocks having the forgetting count value as the extended palm area after performing the forgetting operation.

A control method of a differential touch sensing system according to the present invention includes: setting a forgetting count value for a palm area detected in a current frame; Updating a forgetting count value of an area of the extended palm area defined in a previous frame excluding the palm area; And defining an area where the forgetting count value is maintained by the setting and updating as the extended palm area.

The present invention can distinguish the normal touch area from the palm area, and thus, an accurate touch recognition can be performed.

In addition, the present invention detects a change in the palm area according to the movement of the hand and maintains the forgetting count value for a predetermined period to manage the extended palm area, thereby preventing the palm area from being mistaken as a normal touch, Can be expected.

1 is a block diagram showing a preferred embodiment of a differential touch sensing system according to the present invention;
Figure 2 is a block diagram illustrating a preferred embodiment of the control circuit of Figure 1;
3 is a flow chart showing a preferred embodiment of the control method performed by Fig.
4 is a waveform diagram illustrating sensing data obtained by integrating differential values;
5 is a waveform diagram illustrating a change in differential value.
6 is a map of labeling values to illustrate a method for detecting a palm area.
7 is a view for explaining a change in per-frame oblivion count value;
8 is a view for explaining the change of the palm area according to the movement of the hand;

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It is to be understood that the terminology used herein is for the purpose of description and should not be interpreted as limiting the scope of the present invention.

The embodiments described in the present specification and the configurations shown in the drawings are preferred embodiments of the present invention and are not intended to represent all of the technical ideas of the present invention and thus various equivalents and modifications Can be.

A control circuit and method for a differential touch sensing system according to the present invention discloses a technique for detecting a palm area on a touch panel and recognizing a palm area that is enlarged or reduced according to a movement of a hand, in a manner different from a normal touch.

FIG. 1 is a block diagram of a differential touch sensing system according to an embodiment of the present invention; FIG.

1, the differential touch sensing system may include a PWM control unit 10, a drive circuit 12, a touch panel 14, a sensing circuit 16, an image buffer 18, and a control circuit 20 have.

The PWM control unit 10 provides drive pulses for periodic sensing.

The driving circuit 12 provides the 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 formed variously according to the manufacturer's intention and may be formed to be arranged to intersect with each other or to be arranged side by side so as to share capacitances formed in the spaced spaces.

Therefore, a driving signal is applied to the driving line, and a sensing signal is outputted from the sensing line. When the capacitance changes due to the touch, the sensing signal outputs a sensing signal reflecting the change in capacitance.

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

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

The image buffer 18 may be configured to include a frame-by-frame depot capable of receiving a full frame of the touch panel 14, and may be configured to convert an analog signal transmitted from the sensing circuit 16 to have a digital value And then output. That is, the image buffer 18 outputs the sensing data as a digital signal.

The control circuit 20 receives sensing data which is a digital signal output from the image buffer 18. The sensing data received in the control circuit 20 may be expressed in the form of raw data for the frame of the touch panel 14. [ The row data refers to data having a differential value in which a digital value is mapped by a position of a plurality of scan lines with respect to a frame region of the touch panel 14. [

The control circuit 20 of FIG. 1 may be implemented as firmware for calculating coordinates in a chip.

The control circuit 20 may include functions for realizing touch recognition, coordinate calculation for touch, noise sensing, and the like.

The control circuit 20 configured as an embodiment of the present invention may include a function for recognizing the palm area in a manner different from a normal touch and a function for recognizing a palm area change according to the movement of the hand.

To this end, the control circuit 20 is configured to set the oblivion count value for the palm area detected in the current frame, update the oblivion count value of the area of the extended palm area defined in the previous frame excluding the palm area, And defining an area where the forgetting count value is maintained by the setting and updating as the extended palm area.

The control circuit 20 may further include a step of detecting a palm area, and the step of detecting the palm area may include a labeling step of converting the differential values of the current frame into a labeling value, Scanning the change in the labeling value corresponding to the line to detect the palm area.

In order to realize the above-mentioned function, the control circuit 20 according to the embodiment of the present invention can be exemplified as having the configuration as shown in FIG.

2, the control circuit 20 may include a labeling unit 30, a palm area detecting unit 32, a forgetting operation unit 34, and a palm area expanding unit 36.

The labeling unit 30 receives sensing data having a differential value for each coordinate, i.e., a unit block, in the image buffer 18, and performs a labeling process for converting the differential value of each frame into a labeling value. That is, the labeling unit 30 performs the labeling (S2) of FIG. 3 to obtain the labeling area of FIG. 5 from the differential value of FIG. Here, the sensing data is raw data to which the differential values are mapped.

The labeling process includes mapping the labeling values of the unit blocks having differential values equal to or higher than a predetermined threshold value by unit blocks of the frame.

The labeling area refers to an area having a positive slope equal to or greater than a certain value as shown in FIG. 4 obtained by integrating the differential value of FIG. 5 in the scanning direction.

Preferably, the threshold value is set to a positive value, and the labeling value is preferably an area having a value larger than the threshold value.

A process for obtaining the above-described labeling area will be described with reference to FIG.

The sensing data received in the image buffer 18 is row data in which differential values are mapped on a unit block basis of a frame, and the sensing data has a differential value that varies in the scanning direction for each sensing line as shown in FIG.

 The differential values of the sensing data may have a wide range of patterns in the scanning direction corresponding to the palm touch sensed in a large area. That is, the differential values of the sensing data have a large positive value in the scan direction as in the area P, followed by a small negative value distribution and a large variable value with a large value of the negative value. Lt; / RTI >

For labeling, a threshold value for the differential values of FIG. 5 can be set. The labeling is a process of grouping areas having differential values equal to or greater than the threshold value into one label as shown in FIG. 5, so that the mapped labeling values for the frame can be obtained as shown by the dotted line in FIG.

 At this time, the threshold value may be selected according to the intention of the manufacturer in consideration of the characteristics of the differential values. In the case of FIG. 4, a threshold value of '10' is applied.

In general, the labeling process is performed on a limited region having a positive slope more than a predetermined value instead of performing a large number of positive values having a certain threshold value or more in FIG. 4, thereby reducing a large amount of calculation.

On the other hand, the palm area detecting unit 32 detects the palm area by expanding the labeling area corresponding to each sensing line of the frame in the scanning direction. That is, the palm area detecting unit 32 performs the labeling value scan and the palm area determination (S4) of FIG.

More specifically, the palm area detecting unit 32 determines whether or not the labeling values for the scan direction are in an area equal to or greater than a preset palm area threshold value as shown in FIG. If the determination condition is satisfied, the palm area detection unit 32 determines that the palm area includes unit blocks satisfying the above determination condition.

The operation of the palm area detecting unit 32 will be described in more detail with reference to FIG.

First, the palm area detecting unit 32 expands the palm area by detecting an area of the palm area threshold value '-10' or more preset in the scanning direction on the basis of the labeling area as shown in FIG.

 In the example of FIG. 5, the area P is variable in the order of '15, 15, 25, 5, 8, -8, 6, 2, -2, 9, -5' And thus the area above the palm area threshold value is satisfied.

In determining the palm area, the palm area detecting unit 32 sequentially detects the unit palm areas UP1, UP2, UP3, UP4, and UP5 having a predetermined unit area in the horizontal and vertical directions, as shown in FIG. 6, It can be judged. Then, the palm area detecting unit 32 can detect the palm area as a set of the unit palm areas UP1, UP2, UP3, UP4, and UP5.

In FIG. 6, the unit palm areas UP1, UP2, UP3, UP4, and UP5 are illustrated as including three unit blocks of width and height, respectively.

The palm area detecting unit 32 determines the unit palm area UP1, UP2, UP3, UP4, and UP5 to the last position where the palm area detecting unit 32 holds the labeling area that satisfies the variable range.

The palm area detecting unit 32 detects that the unit palm areas UP1 and UP5 are adjacent to each other even if there is at least one unit block that is determined to be included in the palm area, .

In other words, the unit palm area UP5 includes values (-17, -15, -16, -23, -25, -22) which are not judged as palm areas on the same sensing line or other sensing lines. However, in the unit palm area UP5, a value determined to be included in the palm area in the scanning direction in the labeling area, i.e., '5, 3, -3' exists. Therefore, it can be determined that the unit palm area UP5 includes a unit block having '-5, 3, -3' and the remaining four unit blocks adjacent thereto.

 In addition, the palm area detecting unit 32 detects the number of unit palm areas UP1, UP2, UP3, UP4, and UP5 in the case of FIG. 6 by using the labeling area as a reference, And it is judged that the area is the final palm area when the number of times is kept more than the predetermined threshold number. 8 to distinguish between fingers and palms as shown in F and P in Fig.

As a result, for example, the above-described palm area detecting section 32 can detect the area P as a palm area as shown in Fig. 8 (a). In addition, the region F, which has a small difference region with a large differential value between the positive region and the negative region with respect to the scanning direction, can be detected as a normal touch.

As described above, the embodiment according to the present invention can accurately recognize the normal touch and the palm area, thereby improving the accuracy of the touch recognition.

On the other hand, the forgetting operation unit 34 performs the forgetting operation including the first operation and the second operation.

The first operation corresponds to step S6 in Fig. 3 and sets the oblivion count value to the unit blocks detected as the palm area. The second calculation corresponds to FIG. 8 of FIG. 3, and updates the oblivion count value of the unit blocks defined as the palm area expanded in the previous frame in the area outside the palm area.

The setting in the first operation of the forgetting operation unit 34 means substituting the oblivion count start value with the oblivion count value. The maximum value of the set value of the oblivion count start value can be applied to the oblivion count range. FIG. 7 to illustrate the forgetting operation illustrates the application of the oblivion count range from 0 to 10 and illustrates the application of the oblivion count start value to 10.

The update in the second operation of the forgetting operation unit 34 means decreasing the oblivion count value.

Meanwhile, the palm area extension unit 36 defines the unit blocks having the forgetting count value as the extended palm area after the forgetting operation. In other words, the palm area expanding unit 36 performs step S10 of FIG. 3 to define an area where the oblivion count value does not disappear but has a value of '0' or more as an extended palm area.

The operations of the forgetting operation unit 34 and the palm area expanding unit 36 will be described in detail with reference to FIGS. 7 and 8. FIG.

The forgetting operation unit 34 may perform the forgetting operation for the area P detected as the palm area for the first time as shown in FIG.

7A includes a first operation for setting the oblivion count value in the unit blocks included in the area P, so that the oblivion count start value '10' is set in the unit blocks of the area P do.

The forgetting operation for FIG. 7 (a) does not include a second operation for updating the oblivious count value because there is no extended palm area defined in the previous frame.

In the step of FIG. 7 (a), the palm area expanding unit 36 defines unit blocks in which the perceived count start value '10' is set as an extended palm area.

Thereafter, the forgetting operation unit 34 repeats the forgetting operation corresponding to the result of labeling the sensing data for the frames periodically input.

The dead and forgetting operation unit 34 performs a first operation for setting the oblivion count start value '10' for the unit blocks included in the area Pa detected as the palm area in the current frame as shown in FIG. 7 (b). By the first calculation, the oblivion count start value '10' is collectively set to the unit blocks included in the area Pa.

Then, the forgetting operation unit 34 performs a second operation on the unit blocks of the area A1 excluded from the area Pa defined as the palm area in FIG. 7 (b) to perform the forgetting count value update. That is, the forgetting operation unit 34 decreases the oblivion count value set in the unit blocks of the area A1 by one step. Accordingly, the oblivious count value of the area A1 is reduced from '10' to '9'.

When the forgetting operation by the forgetting operation unit 34 is completed in the step of FIG. 7 (b), the palm area expanding unit 36 enlarges the areas where the forgetting count value is not destroyed by the forgetting operation, It is defined as palm area. That is, in Fig. 7 (b), the area Pa and the area A1 are defined as extended palm areas.

7 (c), the forgetting count start value '10' is set in the area Pb detected as the palm area for the current frame, The oblivious count value set in the unit blocks of the areas A1 and A2 is decreased by one step. In Fig. 7 (c), the area Pb and the areas A1 and A2 are defined as extended palm areas.

As described above, the forgetting operation by the forgetting operation unit 34 and the extended palm area defining by the palm area expanding unit 36 are performed corresponding to the frame periodically sensed.

In this process, if a part of the area defined by the palm area extended by the movement of the hand is not continuously detected as the palm area in the subsequent frame, the oblivion count value of the unit blocks of the corresponding area becomes equal to the area A1 0 'is reached and disappears.

That is, the area or unit block detected as the palm area is not recognized as the extended palm area until it is detected as the palm area again until it is detected as the palm area until the oblivion count value disappears.

Therefore, according to the embodiment of the present invention, since the extended palm area corresponding to the movement of the hand is enlarged and reduced and the forgetting count value is managed, it is possible to prevent the palm area from being mistaken as a normal touch.

More specifically, the palm area is recognized as the area P in Fig. 8 (a) and is recognized as the areas P1 and P2 in Fig. 8 (b) by the movement of the hand and is recognized as the area P3 in Fig. .

In this case, the areas P1 and P2 in Fig. 8 (b) are small in area and can be mistaken for a normal touch.

However, in the embodiment according to the present invention, the area P recognized as the palm area in FIG. 8A is defined as the extended palm area, and the unit defined as the palm area P extended in the previous frame in FIG. The oblivious count value of the blocks is maintained in a reduced state without being destroyed.

Therefore, even if the areas P1 and P2 are not recognized as the palm area in FIG. 8 (b), the areas P1 and P2 are recognized as the extended palm area P by keeping the forgetting count value. As a result, the regions P1 and P2 in FIG. 8 (b) are recognized as the extended palm area without being mistaken for the normal touch.

Therefore, in the differential touch sensing system of the present invention, the palm area can be distinguished from the normal touch, and it is prevented that the temporarily reduced palm area is mistaken as a normal touch, so accurate touch recognition can be performed.

10: PWM control unit 12: drive circuit
14: touch panel 16: sensing circuit
18: image buffer 20: control circuit
30: labeling unit 32: palm area detecting unit
34: forgetting calculation unit 36: palm area expanding unit

Claims (16)

A labeling unit that performs a labeling process of converting a differential value of a unit block of the sensed frame into a labeling value;
A palm area detecting unit for detecting a palm area by scanning a change in the labeling value corresponding to each sensing line of the frame;
A first operation for setting a forgetting count value to the unit blocks corresponding to the palm area and a second operation for updating the forgetting count value of the unit blocks defined as a palm area extended in a previous frame in an area outside the palm area A forgetting operation unit for performing a forgetting operation including two operations; And
And a palm area extension unit for defining the unit blocks having the forgetting count value as the extended palm area after performing the forgetting operation. The method according to claim 1,
Wherein the labeling step comprises mapping a labeling value of unit blocks having a differential value equal to or greater than a predetermined threshold value for each unit block of the frame. 3. The method of claim 2,
Wherein the threshold value is set to a positive value and the labeling value is expressed by a positive value larger than the threshold value. The method according to claim 1,
Wherein the palm area detection unit determines that the palm area includes the unit block having a value larger than the threshold value set as a negative value with respect to the scan direction on the basis of the labeled area. 5. The method of claim 4,
Wherein the palm area detecting unit sequentially determines a unit palm area having a predetermined unit area in the horizontal and vertical directions in the scan direction and detects the palm area as a set of the unit palm areas, Wherein the at least one unit block is determined to be the same size as at least one of the unit blocks. 5. The method of claim 4,
Wherein the palm area detecting unit counts the number of unit palm areas and determines that the palm area is a palm area that is distinguished from a finger area when the palm area has a predetermined number of palm units or more. The method according to claim 1,
Wherein the forgetting operation unit comprises substituting the oblivious count value into the oblivion count start value for the setting for the first operation. 8. The method of claim 7,
Wherein the oblivion count start value is a maximum value among values set in the oblivion count range. 9. The method of claim 8,
Wherein the forgetting operation unit comprises decreasing the forgetting count value for the update for the second operation. Setting a forgetting count value for the palm area detected in the current frame;
Updating a forgetting count value of an area of the extended palm area defined in a previous frame excluding the palm area; And
And defining an area where the forgetting count value is maintained by the setting and updating as the extended palm area. 11. The method of claim 10,
Further comprising detecting the palm area,
Wherein the step of detecting the palm area comprises:
A labeling step of converting the differential values of the current frame into labeling values; And
And detecting the palm area by scanning a change in the labeling value corresponding to each sensing line of the current frame. 12. The method of claim 11, wherein detecting the palm area comprises:
Wherein the determining unit determines that the palm area includes the unit block that maintains at least a predetermined threshold value in a scan direction based on the labeling area maintaining a preset threshold value or more. 13. The method of claim 12,
Wherein the palm area is formed as a set of unit palm areas,
Wherein the unit palm area has a unit area in which the size of the unit palm and the size of the unit palm are determined,
Wherein the unit palm area is defined to be the same size as one or more of the unit blocks determined to be included in the palm area. 11. The method of claim 10,
Wherein the setting of the oblivion count value comprises substituting the oblivion count value with the oblivion count start value. 15. The method of claim 14,
Wherein the forgetting count start value is a maximum value among values set in a forgetting count range. 11. The method of claim 10,
Wherein updating the oblivion count value comprises decreasing the oblivion count value.

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