Touch sensing device and coordinate correction method

The present disclosure relates to a touch sensing device and a coordinate correction method, and more particularly, to a technique of determining a degree, to which a drawn line is curved (a straight line/a curved line), according to gradient values of straight lines that can be generated by touch coordinates and adaptively correcting the coordinates.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority from Republic of Korea Patent Application No. 10-2021-0186738 filed on Dec. 24, 2021, which is hereby incorporated by reference in its entirety.

BACKGROUND

1. Field of Technology

The present disclosure relates to a touch sensing device and a coordinate correction method.

2. Related Technology

Recently, display devices having a touch screen panel that allows a user to apply a touch to a screen through a finger or a touch pen, recognizes and outputs the touch have been widely used. Display devices that receive input information by touching a screen may include a touch sensing device that receives a signal from a touch panel and detects the presence or absence of a touch input and touch coordinates corresponding to a touch position.

However, when a user performs touch drawing on the screen using his/her finger or a touch pen, noise may be included in touch input due to user's unintentional hand tremor or other external factors, and thus there may be a problem in that the result of touch drawing intended by the user is not obtained.

In order to solve the problem of noise included in touch input, smoothing for correcting touch coordinates may be used. However, if touch coordinates for a touch input are excessively corrected, whereby lines are excessively smoothed, even though the lines may be smooth, the lines may be generated in a size or at a location that is not intended by the user. Accordingly, this may give the user an unsatisfactory close contact feeling and this may lead to inconvenience when using the display device.

In view of such circumstances, an object of the present embodiment is to solve the problem that a line drawn by a user is uniformly smoothed regardless of the shape of the line and thus a line having a different size or shape than intended.

The discussions in this section are only to provide background information and does not constitute an admission of prior art.

SUMMARY

To accomplish the aforementioned object, in an aspect, the present disclosure provides a touch sensing device including: a coordinate calculation circuit for calculating touch coordinates for a single touch input generated on a touch screen panel; an indicator generation circuit for generating an angle indicator by calculating a gradient value of a straight line created by connecting the two neighboring touch coordinates among the touch coordinates; and a coordinate correction circuit for generating a filtered coordinate for each touch coordinate by correcting the touch coordinate according to a value of the angle indicator.

To accomplish the aforementioned object, in another aspect, the present disclosure provides a touch sensing device including: a coordinate calculation circuit for calculating touch coordinates for a single touch input generated on a touch screen panel; an indicator generation circuit for generating an angle indicator by calculating a gradient value of a straight line created by connecting the two neighboring touch coordinates; and a coordinate correction circuit for generating a filtered coordinate by correcting a second coordinate using a first coordinate corresponding to a reference coordinate, a first weight to be multiplied by the first coordinate, the second coordinate belonging to the touch coordinates, and a second weight to be multiplied by the second coordinate, wherein values of the first weight and the second weight vary according to a value of the angle indicator.

To accomplish the aforementioned object, in still another aspect, the present disclosure provides a coordinate correction method including: calculating touch coordinates for a single touch input generated on a touch screen panel; generating an angle indicator by calculating a gradient value of a straight line created by connecting two neighboring touch coordinates; and generating an angle filtered coordinate for each touch coordinate by correcting the touch coordinate according to a value of the angle indicator.

As described above, according to the present embodiment, it is possible to improve a degree of user's feeling of close contact with touch and a degree of smoothness of a line drawn by the user by varying a degree of coordinate correction depending on a degree to which the line is straight or curved.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG.1is a block diagram of a display device according to the present embodiment.

Referring toFIG.1, the display device100includes a panel110, a data driver120, a gate driver130, a touch sensing device140, a data processor150, and the like.

At least one of the data driver120, the gate driver130, the touch sensing device140, and the data processor150may be referred to as a display driver. For example, the data driver120may be referred to as a display driver, and a driver including the data driver120and the touch sensing device140may be referred to as a display driver. One driver may be included in another driver. For example, the data driver120may be included in the touch sensing device140. Alternatively, the gate driver130may be included in the data driver120. According to an embodiment, only some components of one driver may be included in another driver.

The data driver120may drive data lines DL connected to pixels P, and the gate driver130may drive gate lines GL connected to the pixels P. In addition, the touch sensing device140may drive touch sensors TS disposed on the panel110.

The data driver120may supply a data voltage to the data lines DL to display an image in pixels P of the panel110. The data driver120may include at least one data driver integrated circuit which may be connected to a bonding pad of the panel110through tape automated bonding (TAB) or a chip on glass (COG) method, may be directly formed on the panel110, or may be formed by being integrated into the panel110in some cases. In addition, the data driver120may be implemented as a chip on film (COF).

The data driver120may receive image data and a data control signal DCS from the data processor150. The data driver120may generate a data voltage according to a grayscale value of each pixel indicated by the image data and drive each pixel.

The gate driver130may supply scan signals to the gate lines GL to turn on/off transistors disposed in the pixels P. The gate driver130may be positioned on only one side of the panel110as shown inFIG.1or may be divided into two and positioned on both sides of the panel110according to a driving method. In addition, the gate driver130may include at least one gate driver integrated circuit which may be connected to the bonding pad of the110through tape automated bonding (TAB) or chip-on-glass (COG) method, may be directly formed on the panel110by being implemented as a gate in panel (GIP), or may be formed by being integrated into the panel110in some cases. In addition, the gate driver130may be implemented as a chip-on-film (COF).

The gate driving device130may receive a gate control signal GCS from the data processor150. The gate control signal GCS may include a plurality of clock signals. In addition, the gate driver130may generate scan signals using the clock signals and supply the scan signals to the gate lines GL.

The panel110may include a display panel and may further include a touch screen panel (TSP). Here, the display panel and the touch screen panel may share some components with each other. For example, a touch sensor TS for sensing a touch in the touch screen panel may be used as a common electrode to which a common voltage is supplied in the display panel (when the display panel is a liquid crystal display (LCD) panel). As another example, the touch sensor TS may be used as a cathode to which a base voltage is supplied in the display panel (when the display panel is an organic light emitting diode (OLED) panel). In view of the fact that the display panel and the touch screen panel share some components with each other, the panel110is also called an integrated panel, but the present invention is not limited thereto.

In addition, although an in-cell type panel is known as a form in which a display panel and a touch screen panel are integrally combined, this is only an example of the aforementioned panel110and the panel to which the present invention is applied is not limited to such an in-cell type panel.

Meanwhile, a plurality of touch sensors TS is disposed in the panel110, and the touch sensing device140may drive the touch sensors TS using a touch driving signal. In addition, the touch sensing device140may generate sensing values for the touch sensors TS according to reaction signals formed in the touch sensors TS in response to the touch driving signal. In addition, the touch sensing device140may calculate touch coordinates of an object10using the sensing values for the plurality of touch sensors TS disposed on the panel110, and the calculated touch coordinates may be transmitted to other devices, for example, a host, and used thereby.

The touch sensing device140may transmit/receive signals to/from the object through the touch sensors TS. The touch sensing device140may calculate touch coordinates using sensing values for a plurality of touch electrodes EL disposed in the panel110, and the calculated touch coordinates are transmitted to other devices, for example, the host, and used thereby.

The data processor150may control timing of each of the drivers120and130through the control signals GCS and DCS. In this respect, the data processor150may be referred to as a timing controller.

FIG.2is a diagram illustrating a configuration of the touch sensing device according to the present embodiment.

The touch sensing device140according to the present embodiment may include a coordinate calculation circuit141, an indicator generation circuit142, and a coordinate correction circuit143.

The coordinate calculation circuit141may calculate touch coordinates for a single touch input generated on the touch panel. The touch input may include press, drawing, release, and the like applied by a user's finger to the touch screen panel using a touch pen or the like. Press of touch input may mean a stage in which an object for touch input touches the touch screen panel to apply a touch. Drawing may mean a stage in which the object touching on the touch panel is dragged without being separated from the touch panel to continuously apply the touch. Release may mean a stage in which the touch input is terminated by releasing the object from the touch panel. Here, a single touch input may mean a touch input composed of press, drawing, and release, and, in brief, may mean a touch input applied with an object touching the touch panel.

The coordinate calculation circuit141may receive the sensing values for the plurality of touch sensors TS disposed in the touch screen panel and calculate touch coordinates using the received values.

The indicator generation circuit142may generate an angle indicator by calculating gradient values of straight lines generated by connecting one of the touch coordinate and another coordinate for each of the touch coordinates.

Calculation of an angle indicator will be described in detail with reference toFIG.4.

The indicator generation circuit142may select touch coordinates spaced apart within a predetermined distance range from among the touch coordinates, and then calculate gradient values using the selected touch coordinates to generate an angle indicator. If only touch coordinates of one frame interval are used, the reliability of gradient characteristics of straight lines and curves included in angle indicators is low, and thus it may be difficult to distinguish between a straight line and a curve. Accordingly, after selecting touch coordinates spaced apart within a predetermined distance range, an angle indicator may be generated through the selected touch coordinates.

The distance range for selecting touch coordinates is not particularly limited, but, for example, touch coordinates spaced apart by a distance within the range of 0.9 to 1.1 mm among the touch coordinates may be selected (sampled) and an angle indicator may be calculated using the same.

The coordinate correction circuit143may generate filtered coordinates for the touch coordinates by correcting the touch coordinates according to the angle indicator values.

The coordinate correction circuit143may receive the angle indicator values generated by the indicator generation circuit142and determine a degree to which coordinates are corrected differently. That is, a degree to which coordinates are corrected may decrease as an angular indicator value increases and may increase as the angle indicator value increases. A large correction degree may mean that a distance between coordinates before and after being corrected is long, and a small correction degree may mean that the distance between the coordinates before and after being corrected is short.

From a different point of view, the coordinate correction circuit143according to the present embodiment may create filtered coordinates obtained by correcting a second coordinate using a first coordinate belonging to touch coordinates, a first weight multiplied by the first coordinate, the second coordinate belonging to the touch coordinates, and a second weight multiplied by the second coordinate, and may vary the values of the first weight and the second weight according to an angle indicator value.

That is, the first coordinate and the second coordinate may be sequentially input touch coordinates, or may be touch coordinates spaced apart by a predetermined distance range. Then, the filtered coordinates may be created by multiplying the first coordinate and the second coordinate by the first weight and the second weight.

The sum of the first weight and the second weight is 1, the larger the value of the angle indicator, the smaller the first weight and the larger the second weight, and the smaller the value of the angle indicator, the larger the first weight and the smaller the second weight.

That is, the second weight is a value multiplied by the filtered second coordinate, and a coordinate correction degree decreases as the second weight increases and increases as the second weight decreases.

The coordinate correction circuit143creates touch coordinates by a single touch input, and filtered coordinates created using the touch coordinates may be output on the display panel in the order of generation and drawn as one line.

The touch sensing device140according to the present embodiment may further include a transmission circuit (not shown).

The transmission circuit may transmit the filtered coordinates created by the touch sensing device140to the host (not shown), and the host may receive the filtered coordinates and use the same.

FIGS.3A and3Bare diagrams illustrating coordinate correction according to the present embodiment.

When a user draws a line by applying a touch to the touch screen panel, the line may be distorted due to jitter noise of a high frequency component. In addition, line drawing may not be performed cleanly due to user's hand tremor or other external environments, and line drawing may include user's unwanted tremor. In order to solve this problem, smoothing may be performed by correcting touch coordinates corresponding to line drawing, as shown inFIGS.3A and3B.

A degree to which a drawn line is smoothed may be proportional to the linearity of a straight line, inversely proportional to the linearity of a curve, and inversely proportional to latency. That is, as the degree to which a line is smoothed increases, a straight line can be drawn as a straight line, a curve can be drawn as a smooth curve, and latency, which means delay time or waiting time, may increase.

When a user draws a line by touch input, drawing performance evaluation may be performed differently for a straight line and a curve. Specifically, the user is sensitive to the smoothness of a line when drawing a straight line and sensitive to closeness between user's touch input and a result of touch when drawing a curve, in general. However, when touch coordinate correction is performed in the same manner for a straight line and a curve as shown inFIGS.3A and3B, a result of touch input may not be derived as desired by the user. That is, if touch coordinates are corrected for a curve and smoothing is strongly applied, the curve may be drawn smaller than intended by the user to smooth the curve.

In order to solve this problem, it is necessary to smooth straight lines and curves created by user's drawing by correcting touch coordinates differently.

Coordinates corrected according to the present embodiment may be referred to as angle filtered coordinates.

FIG.4is a diagram illustrating indicator calculation according to the present embodiment.

As shown inFIG.4, touch input of a user may include a curve like a circle or may be drawn as a straight line. If seven touch coordinates are input as shown inFIG.4, each touch coordinate is connected to a neighboring touch coordinate and thus six gradient values G1, G2, . . . , G6may be created. The gradient values of straight lines may be subtracted from each other and then the absolute values of the resultant values may be added to obtain an angle indicator.

(Gfactoris an angle indicator, G1, G2, . . . , Gnare gradients of straight lines that can be generated by touch coordinates, and n is a natural number equal to or greater than 2)

This is explained in detail. If n touch coordinates are created by one touch input, each of the n touch coordinates is connected to a neighboring touch coordinate and thus n−1 straight lines can be created and n−1 gradient values corresponding thereto can be derived. In addition, values obtained by subtracting the gradient values of the straight lines from each other and summing the absolute values thereof may be an angle indicator.

The angle indicator can be represented as the following formula.

(Gfactoris an angle indicator, G1, G2, . . . , Gnare gradients of straight lines that can be generated by touch coordinates, and n is a natural number equal to or greater than 2)

If touch input is applied in the form of a straight line, the gradients of straight lines that can be created by touch coordinates created by the touch input will be identical or similar. Therefore, the result of calculation of the aforementioned angle indicator Gfactorwill be 0 or a relatively small value. However, if touch input is applied in the form of a curve, the gradients of straight lines that can be created by touch coordinates created by the touch input will have different values. Therefore, the result of calculation of the aforementioned angle indicator Gfactorwill be a larger value than that obtained when the touch input is applied in the form of a straight line.

As described above, it is possible to determine how much the touch input includes straight line parts or curved parts according to the value of the angle indicator, and thus coordinate correction can be adaptively applied.

FIG.5is a diagram illustrating coordinate correction test results according to the present embodiment.

In order to measure the reliability of the angle indicator Gfactoraccording to the present embodiment for straight lines/circle lines with respect to drawn lines, angle indicators were calculated for a case in which touch coordinates spaced apart by a certain distance range are selected (sampling) and a case in which the touch coordinates are not selected (non-sampling) for straight lines (⋄) drawn as straight lines and circle lines (▪) drawn as circles.

Here, a line drawn as a straight line means a line drawn by a user with the intention of drawing a straight line and may be a line including noise caused by user's hand tremor rather than a perfect straight line, and a circle line drawn as a circle means a circle line drawn by a user with the intention of drawing a circle and may be a circle line including noise caused by user's hand tremor rather than a perfect circle line.

The graphs shown inFIG.5are results of calculating angle indicators using results of drawing the test sets shown inFIG.5.

When the numerical values of the graphs shown inFIG.5are represented as the following table.

For non-sampling touch coordinates, an average angle indicator Gfactorof 55 and a maximum angle indicator Gfactorof 102 were calculated for circle lines, and an average angle indicator Gfactorof 45 and a maximum angle indicator Gfactorof 129 were calculated for straight lines. It can be ascertained from the non-sampling graph ofFIG.5that Gfactorvalues are not well distinguished between straight lines and circle lines. This may mean that the reliability of distinguishing between straight lines and circle lines is low when the angle indicator Gfactoris calculated using the non-sampling touch coordinates.

For sampling touch coordinates, an average angle indicator Gfactorof 61 and a maximum angle indicator Gfactorof 145 were calculated for circle lines, and an average angle indicator Gfactorof 13 and a maximum angle indicator Gfactorof 45 were calculated for straight lines. It can be ascertained from the sampling graph ofFIG.5that Gfactorvalues are relatively well distinguished between straight lines and circle lines. This may mean that the reliability of distinguishing between straight lines and circle lines can be relatively increased when the angle indicator Gfactoris calculated using the sampling touch coordinates.

Therefore, when touch coordinates spaced apart by a predetermined distance range are selected and then the angle indicator Gfactoris calculated, the performance of correction can be improved.

FIG.6is a diagram illustrating a coordinate correction method according to the present embodiment.

In the coordinate correction method according to the present embodiment, step S610of calculating touch coordinates for a single touch input generated on the touch screen panel may be performed.

A single touch input may mean a touch input that is continuously applied with a user's finger, a touch pen, or the like touching the touch screen panel.

In the coordinate correction method according to the present embodiment, step S620of calculating gradient values of straight lines generated by connecting neighboring touch coordinates for each touch coordinate to generate an angle indicator may be performed.

If n touch coordinates are created by the single touch input, the n touch coordinates can be connected to neighboring touch coordinates to create n−1 straight lines, and n−1 gradient values corresponding thereto can be derived. In addition, a value obtained by subtracting the gradient values of the straight lines from each other and then summing the absolute values thereof may be an angle indicator.

If the touch input is applied in the form of a straight line, the gradients of the straight lines that can be created by touch coordinates created by the touch input will be identical or similar. Therefore, the angle indicator Gfactorcalculated according to the above-described angle indicator calculation will be 0 or a relatively small value. However, if the touch input is applied in the form of a curve, the gradients of the straight lines that can be created by the touch coordinates created by the touch input will have different values. Therefore, the angle indicator Gfactorcalculated according to the above-described angle indicator calculation will be larger than that calculated when the touch input is applied in the form of a straight line.

As described above, it is possible to determine how much touch input includes straight line parts or curved parts according to the value of the angle indicator, and thus coordinate correction can be adaptively applied.

In the coordinate correction method according to the present embodiment, step S630of generating angle filtered coordinates for the touch coordinates by correcting the touch coordinates according to the value of the angle indicator may be performed.

By adaptively and flexibly correcting the touch coordinates according to the value of the angle indicator, a degree to which the coordinates are corrected can be increased for a straight line with a small angle indicator and can be decreased for a curve with a large angle indicator.

In the coordinate correction method according to the present embodiment, the step of generating distance filtered coordinates by correcting the angle filtered coordinates depending on the distances of the angle filtered coordinates may be additionally performed. Here, the angle filtered coordinates obtained by correcting the touch coordinates according to the angle indicator are corrected once again depending on the distance between coordinates, and a correction degree may be decreased as the distance between angle filtered coordinates increases and may be increased as the distance decreases.

The coordinate correction method for correcting coordinates depending on a distance between coordinates will be described in detail in a first embodiment of touch coordinate correction.

FIG.7is a diagram illustrating the first embodiment of touch coordinate correction.

The first embodiment shown inFIG.4illustrates a method of generating filtered coordinates by correcting touch coordinates based on the distance between touch coordinates.

As shown inFIG.4, a (k−1)-th touch coordinate Pk-1and a k-th touch coordinate Pkwhich have been input can be corrected to a (k−1)-th filtered coordinate Qk-1and a k-th filtered coordinate Qk.

The touch coordinate Pkcan be corrected to the filtered coordinate Qkthrough the following formula.
Qk=(1−α)×Qk-1+α×Pk

(α is a coefficient.)

Here, the coefficient α may vary depending on the distance between the (k−1)-th touch coordinate Pk-1and the k-th touch coordinate Pk, and specifically, the coefficient α of the above formula may increase as the distance between the (k−1)-th touch coordinate Pk-1and the k-th touch coordinate Pkincreases and may decrease as the distance between the (k−1)-th touch coordinate Pk-1and the k-th touch coordinate Pkdecreases.

Therefore, considering that the touch coordinate Pk is corrected to the filtered coordinate Qk, the correction degree may decrease as the distance between the (k−1)-th touch coordinate Pk-1and the k-th touch coordinate Pkincreases and may increase as the distance between the (k−1)-th touch coordinate Pk-1and the k-th touch coordinate Pkdecreases.

In addition, the distance between touch coordinates may vary depending on a user's drawing speed. That is, if the user's drawing speed is high, the distance between touch coordinates may be long and thus correction of touch coordinates according to the first embodiment may be weakly performed, and if the user's drawing speed is low, the distance between touch coordinates may be short and thus correction of touch coordinates according to the first embodiment may be strongly performed.

The first embodiment can be used along with coordinate correction using an angle indicator according to the present embodiment. Specifically, touch coordinates may be corrected using an angle indicator according to the present embodiment, and then the filtered coordinates created using the angle indicator may be corrected again according to the coordinate correction method using a distance between coordinates according to the first embodiment. Alternatively, touch coordinates may be corrected according to the coordinate correction method using a distance between coordinates according to the first embodiment, and then the created filtered coordinates may be corrected again according to the coordinate correction method using an angle indicator according to the present embodiment.

Coordinates corrected according to the first embodiment may also be referred to as distance filtered coordinates.

FIG.8is a diagram illustrating a second embodiment of touch coordinate correction.

The second embodiment shown inFIG.8illustrates a method of generating predicted coordinates and correcting coordinates based thereon to create final coordinates. Filtered coordinates are used when the second embodiment is implemented, and these filtered coordinates may be obtained by coordinate correction using an angle indicator according to the present embodiment or may be obtained by coordinate correction using a distance between coordinates according to the first embodiment.

The second embodiment may include touch coordinates (◯), predicted coordinates (Δ), filtered coordinates (□), and final coordinates (●).

Specifically, as shown inFIG.8, a 0-th touch coordinate, a first touch coordinate, a second touch coordinate, a third touch coordinate, and a fourth touch coordinate may be sequentially created according to user's touch input.

Then, coordinate correction using an angle indicator according to the present embodiment or the coordinate correction method using a distance between coordinates according to the first embodiment may be performed on the touch coordinates to create a first filtered coordinate, a second filtered coordinate, a third filtered coordinate, and a fourth filtered coordinate. That is, as filtered coordinates according to the second embodiment, angle filtered coordinates or distance filtered coordinates may be used.

In addition, a second predicted coordinate, a third predicted coordinate, and a fourth predicted coordinate may be created. The second predicted coordinate may be created on a straight line in the direction of touch input in which the 0-th touch coordinate and the first touch coordinate are positioned. The distance between the second predicted coordinate and the first touch coordinate is not particularly limited, but may be the same as the distance between the 0-th touch coordinate and the first touch coordinate, or may be shorter or longer than the distance between the 0-th touch coordinate and the first touch coordinate. In this way, the third predicted coordinate may be created on a straight line on which the first touch coordinate and the second touch coordinate are positioned, and the fourth predicted coordinate may be created on a straight line on which the second touch coordinate and the third touch coordinate are positioned. A method of generating predicted coordinates in this way may be referred to as extrapolation.

Then, final coordinates may be created using the predicted coordinates and the filtered coordinates according to the following formula.
Pkfinal=β×Pkpredict+(1−β)×Pkfiltered

Therefore, referring toFIG.8, the second final coordinate can be created using the second filtered coordinate and the second predicted coordinate, the third final coordinate can be created using the third filtered coordinate and the third predicted coordinate, and the fourth final coordinate can be created using the fourth filtered coordinate and the fourth predicted coordinate.

According to the second embodiment, a user predicts a direction in which the user will draw a line in advance and corrects touch coordinates based thereon using predicted coordinates, and thus latency performance in drawing is improved and feeling of close contact during drawing is improved.