TW201504876A - Palm rejection method - Google Patents

Abstract

A palm rejection method is provided for use in a device which adopts a touch panel. When a user rests his hand on the touch panel for inputting data, the palm rejection method differentiates between intentional and inadvertent contact points according to user hand or writing habit, thereby increasing the accuracy of the touch panel.

Description

Prevent palm touch method

The invention relates to a method for preventing palm touch, especially a method for preventing palms from being touched according to a user's palm or writing manner.

In today's various consumer electronics market, because the product design is light, thin, short, and small, there is not enough space to accommodate traditional input devices such as keyboards and mice, especially in the tablet design that is user-friendly. Driven by demand, display devices with touch panels have gradually become one of the key components of various electronic products, such as personal digital assistants (PDAs), mobile phones, and smart phones. Portable electronic devices such as mobile phones or tablets.

The touch panel uses a sensor to detect changes in resistance, capacitance, pressure or light intensity caused by a touch event to determine the touch coordinates, and then outputs the touch coordinates to the system. However, when the user inputs data on the touch panel in the writing mode, it is easy to get used to leaning the palm on the screen. At this time, the sensor senses the movement of the palm and the finger at the same time, and the detection cannot be detected correctly. Input information about the user's writing behavior.

The present invention provides a method for preventing accidental touch of a touch panel, which includes receiving a plurality of touch coordinates when a touch event is detected, and recording a first coordinate value representing one of each touch coordinates and a first Two coordinate values, wherein the first coordinate value is related to one a first direction, the second coordinate value is related to a second direction, and the first direction and the second direction are perpendicular to each other; respectively, determining a plurality of determination distances corresponding to the plurality of touch coordinates, wherein the plurality of determination distances Determining a specific determination distance in the distance is related to a specific touch coordinate and at least one other touch coordinate in the plurality of touch coordinates; and discarding the specific touch coordinate when the specific determination distance is not greater than a predetermined distance.

110~160‧‧‧Steps

F ₀ ~F ₆ ‧‧‧Touch coordinates

F ₀ '~F ₆ '‧‧‧Reference touch coordinates

Figure 1 is a flow chart of a method for preventing palm touch by mistake in the present invention.

2 to 12 are schematic views showing a method of preventing palm touch by mistake in the embodiment of the present invention.

Figure 1 is a flow chart of a method for preventing palm rejection in the present invention, which comprises the following steps:

Step 110: Determine a predetermined distance R, and perform step 120.

Step 120: Determine the number of touch coordinates when the touch event is detected: if a plurality of touch coordinates are detected, go to step 130; if a single touch coordinate is detected, go to step 160.

Step 130: Record the coordinate values of the plurality of touch coordinates and perform the comparison procedure accordingly, and perform step 140.

Step 140: Determine whether a target coordinate value can be obtained after executing the comparison program: if yes, execute step 150; if not, execute step 120.

Step 150: Output the target coordinate value, and perform step 120.

Step 160: Output a coordinate value of a single touch coordinate, and perform steps 120.

In step 110, the predetermined distance R may be related to the size of the user's palm or the writing habit, and the manner of determining the predetermined distance R will be described in detail later in the specification. In step 120, the present invention determines whether a single or a plurality of touch coordinates are received when a touch event is detected. If only a single touch coordinate is received, the present invention performs step 160 to output the coordinate value of the single touch coordinate; if a plurality of touch coordinates are received, the present invention performs step 130 to record the coordinates of the plurality of touch coordinates. Value and compare the program accordingly.

2 to 5 are schematic diagrams showing a method of determining a false touch according to an embodiment of the present invention. The black dot represents all touch coordinates received when a touch event is detected, where F ₀ represents the touch coordinates detected by the user when inputting with a finger or a stylus, and F ₁ ~F _N represents the use of The touched coordinates detected by the palm of the hand. Figures 2 through 5 show an embodiment with N = 6, but without limiting the scope of the invention, N can be any positive integer. When performing the step 130, the present invention first records the coordinate values (x ₀ , y ₀ )~(x ₆ , y ₆ ) of all the touch coordinates F ₀ to F ₆ , and then performs the comparison procedure accordingly.

In the embodiment shown in Figures 2 and 3, step 130 uses a distance algorithm to find the total distance between each touch coordinate and other touch coordinates for the alignment procedure. For example, for a line segment between two points F ₁ (x ₁ , y ₁ ) and F ₂ (x ₂ , y ₂ ) on the coordinate plane, the length can be found according to the Bishop's theorem. For convenience of explanation, the embodiment here is simplified to | x ₁ -x ₂ |+| y ₁ -y ₂ |. First, find the distance between each of the touch coordinates of the touch coordinates F ₀ ~ F ₆ (indicated by the broken lines in Figures 2 and 3), where D ₀₁ represents the touch coordinates F ₀ and F ₁ The distance between them, D ₀₂ represents the distance between the touch coordinates F ₀ and F ₂ , ..., D ₅₆ represents the distance between the touch coordinates F ₅ and F ₆ , and the values are as follows: D ₀₁ = |x ₀ -x ₁ |+|y ₀ -y ₁ |

D ₀₂ =|x ₀ -x ₂ |+|y ₀ -y ₂ |

...

D ₅₆ =|x ₅ -x ₆ |+|y ₅ -y ₆ |

Then, the total distance S0~S6 between each touch coordinate and other touch coordinates is respectively determined, where S0 represents the total distance between the touch coordinate F ₀ and the touch coordinates F ₁ ~F ₆ , and S1 represents the touch The total distance between the touch target F ₁ and the touch coordinates F ₀ , F ₂ ~F ₆ , ..., S6 represents the total distance between the touch coordinate F ₆ and the touch coordinates F ₀ ~ F ₅ , the value thereof As shown below: S0=D ₀₁ +D ₀₂ +D ₀₃ +D ₀₄ +D ₀₅ +D ₀₆

S1=D ₀₁ +D ₁₂ +D ₁₃ +D ₁₄ +D ₁₅ +D ₁₆

S3=D ₀₃ +D ₁₃ +D ₂₃ +D ₃₄ +D ₃₅ +D ₃₆

S4=D ₀₄ +D ₁₄ +D ₂₄ +D ₃₄ +D ₄₅ +D ₄₆

S5=D ₀₅ +D ₁₅ +D ₂₅ +D ₃₅ +D ₄₅ +D ₅₆

S6=D ₀₆ +D ₁₆ +D ₂₆ +D ₃₆ +D ₄₆ +D ₅₆

Then, the maximum value is selected from the total distances S0 to S6, and it is determined whether the maximum total distance is greater than the predetermined distance R. When the user touches the panel by mistake, the touch command is issued, and all the touch coordinates detected at this time are as shown in FIG. 2, wherein the touch coordinates F ₁ to F _{6 of the} palm are close to each other, and the touch of the finger The touch coordinate F0 and the other hand's touch coordinates F ₁ ~F ₆ are far apart, so S0 is the maximum total distance. When the user accidentally touches the panel, the touch command is not released. At this time, all the touch coordinates detected are as shown in FIG. 3, wherein the touch coordinates F ₁ to F _{6 of the} palm are close to each other, and the total distance S1 is The value of ~S6 does not differ too much, so S6 is assumed to be the maximum total distance.

As shown in FIG. 2 and FIG. 3, the touch coordinates corresponding to the maximum total distance may be where the actual input data (touch coordinate F ₀ ) or the palm error contact (touch coordinate F ₆ ), so the present invention It is further determined based on the predetermined distance R. In the step 110, the value of the predetermined distance R can be determined according to the size of the user's palm or the writing habit, so that the distance between the user's finger and the palm can be appropriately described. When the maximum total distance S0 is greater than the predetermined distance R, it can be determined that the touch coordinate F ₀ is the actual input data, and the touch coordinate F ₀ is locked as the target coordinate value; when the maximum total distance S6 is not greater than the predetermined distance R , it can be determined that the touch coordinate F ₆ is the palm error contact, so no target coordinate value will be generated.

In the embodiment shown in Figures 4 through 7, the present invention performs a distance comparison in step 130 based on the distance between two adjacent touch coordinates. First, you can select the touch coordinates adjacent to the X-axis direction (as indicated by the double-arrow dotted lines in Figures 4 and 5), or select the touch coordinates adjacent to the Y-axis direction (as shown in Figure 6 and The double arrow in Figure 7 shows the distance between two adjacent touch coordinates. If the distance between two adjacent touch coordinates is not greater than the predetermined distance R, two adjacent touch coordinates are deleted; if the distance between two adjacent touch coordinates is greater than the predetermined distance R, two adjacent touch coordinates are retained . When all the touch coordinates are compared in the same way, if there is a reserved touch coordinate, the touch coordinate is locked as the target coordinate value.

According to the writing habits of most people, the figures are shown in Fig. 6 and Fig. 7. In the embodiment shown in Figures 6 and 7, step 130 uses a distance algorithm to find the distances D ₀₁ , D ₁₂ , D ₃₄ and D ₅₆ between two adjacent touch coordinates in the Y-axis direction. Where D ₀₁ represents the distance between the touch coordinates F ₀ and F ₁ , D ₁₂ represents the distance between the touch coordinates F ₁ and F ₂ , and D ₃₄ represents the distance between the touch coordinates F ₃ and F ₄ , And D ₅₆ represents the distance between the touch coordinates F ₅ and F ₆ , and its value is as follows: D ₀₁ =|x ₀ -x ₁ |+|y ₀ -y ₁ |

D ₁₂ =|x ₁ -x ₂ |+|y ₁ -y ₂ |

D ₃₄ =|x ₃ -x ₄ |+|y ₃ -y ₄ |

D ₅₆ =|x ₅ -x ₆ |+|y ₅ -y ₆ |

For example, in the embodiment shown in FIG. 6, if the comparison program starts from a larger Y coordinate value, the first two adjacent touch coordinates are selected as F ₀ and F ₁ , and the distance is known after the comparison. D _{01 is} greater than the predetermined distance R, at which time the touch coordinates F ₀ and F ₁ are retained; then the two adjacent touch coordinates are selected as F ₁ and F ₂ , and after the comparison, the distance D _{12 is} not greater than the predetermined distance R, At this time, the touch coordinates F ₁ and F ₂ are deleted, so only the touch coordinates F ₀ are retained; then the two adjacent touch coordinates selected are F ₃ and F ₄ , and the distance D _{34 is} not greater than the predetermined distance after the comparison. R, the touch coordinates F ₃ and F ₄ will be deleted at this time, so only the touch coordinates F ₀ are retained; the last two adjacent touch coordinates are F ₅ and F ₆ , and the distance D _{56 is} not greater than predetermined distance R, the touch coordinates at this time are deleted F ₅ and F _6, thus finally retain only touch coordinates F _0, this case can be locked touch coordinates F ₀ as the target coordinates. Similarly, if the comparison program starts from the smaller Y coordinate value, the first two adjacent touch coordinates are selected as F ₅ and F ₆ , and after the comparison, the distance D _{56 is} not greater than the predetermined distance R, and will be deleted. Touch the coordinates F ₅ and F ₆ ; then select two adjacent touch coordinates as F ₃ and F ₄ , and after the comparison, the distance D _{34 is} not greater than the predetermined distance R, and the touch coordinates F ₃ and F are deleted. ₄ ; then the two adjacent touch coordinates are selected as F ₁ and F ₂ , and after the comparison, the distance D _{12 is} not greater than the predetermined distance R, and the touch coordinates F ₁ and F ₂ are deleted at this time; touch coordinates F ₀ and F _6, the distance D ratio that is greater than a predetermined distance after ₀₆ R, the touch coordinates at this time will be retained and F ₀ F _6, F ₆ since the touch coordinates previously been deleted, and therefore only the last The remaining touch coordinates F _0, this case can be locked touch coordinates F ₀ as the target coordinates.

In the embodiment shown in Figure 7, the distances D ₁₂ , D ₃₄ and D ₅₆ between two adjacent touch coordinates are no greater than a predetermined distance, regardless of whether the alignment program starts from a larger or smaller Y coordinate value. R, the touch coordinates F ₁ to F ₆ are deleted at this time, so no touch coordinates are retained.

In an embodiment of the invention, the distance comparison may be performed only according to the distance between two adjacent touch coordinates in one of the X-axis direction or the Y-axis direction, that is, when a specific touch coordinate and other The distance between the adjacent touch coordinates in the X-axis or Y-axis direction needs to be greater than the predetermined distance R, and the specific touch coordinates are locked after the program is compared to provide the target coordinate value. In another embodiment of the present invention, the distance comparison can be performed simultaneously according to the distance between two adjacent touch coordinates in the X-axis direction and the Y-axis direction, that is, when a specific touch coordinate and the other are on the X-axis. The distance between the adjacent touch coordinates and the Y-axis direction needs to be greater than the predetermined distance R, and the specific touch coordinates are locked after the program is compared to provide the target coordinate value.

In the embodiment shown in Figures 8 through 11, the present invention performs an alignment in step 130 based on the X or Y coordinates of two adjacent touch points. First, you can select the touch coordinates adjacent to the X-axis direction (as indicated by the double-arrow dotted lines in Figures 8 and 9), or select the touch coordinates adjacent to the Y-axis direction (as in Figure 10 and In the ellipse of the double arrow in Figure 11, the X coordinate difference or the Y coordinate difference between two adjacent touch coordinates is calculated. If the X coordinate difference between two adjacent touch coordinates is not greater than the predetermined distance R _x or the Y coordinate difference is not greater than the predetermined distance R _y , then the two adjacent touch coordinates are deleted, where R _x is the predetermined X coordinate Distance; R _y is a predetermined distance of the Y coordinate; if the X coordinate difference between two adjacent touch coordinates is greater than the predetermined distance R _x or the Y coordinate difference is greater than the predetermined distance R _y , then the two adjacent touch coordinates are retained . When all the touch coordinates are compared in the same way, if there is a reserved touch coordinate, the touch coordinate is locked as the target coordinate value.

According to the writing habits of most people, the figures are shown in Fig. 10 and Fig. 11. In the embodiment shown in Figs. 10 and 11, the Y coordinate difference values ΔY ₀₁ , ΔY ₁₂ , ΔY ₃₄ and ΔY ₅₆ between two adjacent touch coordinates in the Y-axis direction are calculated. Where ΔY ₀₁ represents the Y coordinate difference between the touch coordinates F ₀ and F ₁ , ΔY ₁₂ represents the Y coordinate difference between the touch coordinates F ₁ and F ₂ , and ΔY ₃₄ represents the touch coordinate F The Y coordinate difference between ₃ and F ₄ , and ΔY ₅₆ represents the Y coordinate difference between the touch coordinates F ₅ and F ₆ , the values of which are as follows: Y ₀₁ =|y ₀ -y ₁ |

Y ₁₂ =|y ₁ -y ₂ |

Y ₃₄ =|y ₃ -y ₄ |

Y ₅₆ =|y ₅ -y ₆ |

In the embodiment shown in Fig. 10, if the comparison procedure starts from a larger Y coordinate value, the first two adjacent touch coordinates are selected as F ₀ and F ₁ , and the Y coordinate difference Δ is obtained after the comparison. Y _{01 is} greater than the predetermined distance R _y , at which time the touch coordinates F ₀ and F ₁ are retained; then the two adjacent touch coordinates are selected as F ₁ and F ₂ , and the Y coordinate difference ΔY _{12 is} not known after the comparison. More than the predetermined distance R _y , the touch coordinates F ₁ and F ₂ are deleted at this time, so only the touch coordinates F ₀ are retained; then the two adjacent touch coordinates are selected as F ₃ and F ₄ , and the Y is known after the comparison. The coordinate difference ΔY _{34 is} not greater than the predetermined distance R _y , at which point the touch coordinates F ₃ and F ₄ are deleted, so only the touch coordinates F ₀ are retained; the last two adjacent touch coordinates are F ₅ and F ₆ After the comparison, it is known that the Y coordinate difference value ΔY _{56 is} not greater than the predetermined distance R _y , and the touch coordinates F ₅ and F ₆ are deleted at this time, so only the touch coordinate F ₀ is retained at the end, and the touch can be locked at this time. The coordinate F _{0 is} taken as the target coordinate value. Similarly, if the comparison procedure starts from a smaller Y coordinate value, the first two adjacent touch coordinates are selected as F ₅ and F ₆ , and the Y coordinate difference ΔY _{56 is} not greater than the predetermined distance R _y after the comparison. At this time, the touch coordinates F ₅ and F ₆ are deleted; then the two adjacent touch coordinates are selected as F ₃ and F ₄ , and the Y coordinate difference ΔY _{34 is} not greater than the predetermined distance R _y after the comparison. The touch coordinates F ₃ and F ₄ are deleted; then the two adjacent touch coordinates are selected as F ₁ and F ₂ , and the Y coordinate difference ΔY _{12 is} not greater than the predetermined distance R _y after the comparison. The touch coordinates F ₁ and F _{2 are} deleted; only the touch coordinates F ₀ and F ₆ are left last, and since the previous comparison, it is known that the Y coordinate difference ΔY _{56 is} not greater than the predetermined distance R _y , the touch coordinate F ₅ and F ₆ have been removed, so the final will be left only the touch coordinates F _0, then you can lock the touch coordinates F ₀ as the target coordinates.

In the embodiment shown in Fig. 11, the Y coordinate difference values ΔY ₁₂ , ΔY ₃₄ and ΔY between two adjacent touch coordinates are started regardless of whether the comparison program starts from a larger or smaller Y coordinate value. _{56 is} not greater than the predetermined distance R _y , and the touch coordinates F ₁ to F ₆ are deleted at this time, so that no touch coordinates are retained.

In an embodiment of the invention, the comparison may be based only on the X coordinate difference between two adjacent touch coordinates in the X-axis direction or the Y coordinate difference between two adjacent touch coordinates in the Y-axis direction. The program, that is, the difference between the X coordinate difference between a specific touch coordinate and other adjacent touch coordinates in the X-axis direction or the Y coordinate difference between the adjacent touch coordinates in the Y-axis direction is greater than the predetermined Distance R _y , this specific touch coordinate is locked after the program is compared to provide the target coordinate value. In other embodiments of the present invention, the X coordinate difference between two adjacent touch coordinates in the X-axis direction and the Y coordinate difference between two adjacent touch coordinates in the Y-axis direction may be simultaneously compared. The program, that is, the X coordinate difference between a specific touch coordinate and other adjacent touch coordinates in the X-axis direction and the Y coordinate difference between the adjacent touch coordinates in the Y-axis direction are greater than The predetermined distance R _y is locked after the program is compared to provide the target coordinate value.

In an embodiment of the invention, the predetermined distance R may be input by the user or provided by the system for the user to select. In another embodiment of the invention, The system may require the user to put the palm of the hand on the touch panel in a writing state, and then determine the optimal predetermined distance R according to the user's hand shape.

FIG. 12 is a schematic diagram of the method for preventing accidental touch of the touch panel according to the present invention. When the user puts the palm of the hand on the touch panel, the system can detect the reference touch coordinate F ₀ ' corresponding to the user's finger or the stylus, and corresponds to the user's palm area. Refer to the touch coordinates F ₁ '~F _M '. Fig. 12 shows an embodiment of M = 6, but does not limit the scope of the invention, and M can be any positive integer.

In an embodiment of the performing step 110 of the present invention, a distance algorithm may be used to find the total reference distance between each reference touch coordinate and other reference touch coordinates. For details, refer to the previous related FIG. 2 and The description of Fig. 3 is not described here. As shown in Fig. 12, the reference total distance S0' between the reference touch coordinates F ₀ ' and the reference touch coordinates F ₁ '~F ₆ ' is the maximum value, and the predetermined distance R can be set to S0'+ ΔR, where ΔR is an adjustment value related to the identification error.

In another embodiment of the performing step 110 of the present invention, the reference distance between two adjacent reference touch coordinates in the X-axis direction or the Y-axis direction can be obtained. For details, refer to the previous FIGS. 4 to 7 The description of the figure is not described here. As shown in FIG. 12, the reference distance D ₀₁ ' between the reference touch coordinate F ₀ ' and the reference touch coordinate F ₁ ' is the maximum value, and the predetermined distance R can be set to D ₀₁ '+ΔR, Where ΔR is an adjustment value related to the identification error.

In another embodiment of the performing step 110 of the present invention, a reference X coordinate difference between two adjacent reference touch coordinates in the X-axis direction or between two adjacent reference touch coordinates in the Y-axis direction may be obtained. Refer to the description of the Y coordinate difference. For details, refer to the previous descriptions related to Figure 8 to Figure 11, and no further details are provided here. As shown in Fig. 12, the reference X coordinate difference ΔX ₀₁ ' between the reference touch coordinate F ₀ ' and the reference touch coordinate F ₁ ' or the reference Y coordinate difference ΔY ₀₁ ' is the maximum value. The predetermined distance R can be set to ΔX ₀₁ '+ΔR or ΔY ₀₁ '+ΔR, where ΔR is an adjustment value related to the identification error.

The invention provides a method for preventing the palm from being touched by mistake, and the device using the touch panel can be realized by a soft body or a firmware. When the user inputs data on the touch panel in the writing mode, the present invention can distinguish the actual touch coordinates and the accidental touch coordinates according to the user's palm or writing manner, thereby improving the recognition degree of the touch panel.

110~160‧‧‧Steps

Claims (11)

A method for preventing accidental touch of a touch panel, comprising: receiving a plurality of touch coordinates when detecting a touch event, recording a first coordinate value and a second coordinate representing one of each touch coordinate a value, wherein the first coordinate value is related to a first direction, the second coordinate value is related to a second direction, and the first direction and the second direction are perpendicular to each other; respectively, corresponding to the plurality of touches a plurality of first determining distances of the coordinates, wherein a specific first determining distance of the plurality of first determining distances is related to a specific touch coordinate and at least one other touch coordinate of the plurality of touch coordinates; and when the specific When the first judgment distance is not greater than a first predetermined distance, the specific touch coordinates are discarded. The method of claim 1, wherein the specific first determination distance is a sum of distances between the particular touch coordinate and all other touch coordinates. The method of claim 2, further comprising: detecting a plurality of reference touch coordinates and recording the plurality of reference touches when a user places the palm in a writing state on a touch panel; a coordinate value of the touch target; determining, according to the coordinate value of the plurality of reference touch coordinates, a total of a plurality of reference distances between each reference touch coordinate and all other reference touch coordinates; and the plurality of reference distances The sum of the maximum reference distances in the sum is set to the first predetermined distance. The method of claim 1, wherein the specific first determining distance is a distance between the specific touch coordinate and a first touch coordinate of the plurality of touch coordinates, and the specific touch coordinate and the The first touch coordinate is a pair of adjacent touch coordinates according to the first direction. The method of claim 4, further comprising: when at least two of the plurality of first determination distances are greater than the first predetermined distance, and the specific first determination distance is greater than the first predetermined distance And determining a second determination distance corresponding to one of the specific touch coordinates, wherein the second determination distance is a distance between the specific touch coordinate and a second touch coordinate of the plurality of touch coordinates, And the specific touch coordinates and the second touch coordinate system are two adjacent touch coordinates according to the second direction; and when the second determination distance is not greater than a second predetermined distance, discarding the specific touch coordinates . The method of claim 5, further comprising: detecting a plurality of reference touch coordinates and recording each reference touch when a user places the palm in a writing state on a touch panel; a first reference coordinate value and a second reference coordinate value, wherein the first reference coordinate value is related to the first direction, and the second reference coordinate value is related to the second direction; for the plurality of reference touches Each of the two adjacent reference touch coordinates in the first direction respectively obtains a plurality of first reference coordinate differences; and for each of the plurality of reference touch coordinates, each of the two adjacent parameters according to the second direction Taking a touch coordinate, respectively determining a plurality of second reference coordinate differences; setting a maximum first reference coordinate difference of the plurality of first reference coordinate differences as the first predetermined distance; and the plurality of A maximum second reference coordinate difference value of the two reference coordinate differences is set to the second predetermined distance. The method of claim 1, wherein the specific first determining distance is between a first coordinate value of the specific touch coordinate and a first coordinate value of a first touch coordinate of the plurality of touch coordinates The difference, and the specific touch coordinate and the first touch coordinate are two adjacent touch coordinates according to the first direction. The method of claim 7, further comprising: when at least two of the plurality of first determination distances are greater than the first predetermined distance, and the specific first determination distance is greater than the first predetermined a second determination distance corresponding to one of the specific touch coordinates, wherein the second determination distance is a second coordinate value of the specific touch coordinate and a second touch of the plurality of touch coordinates a difference between the second coordinate values of the coordinates, and the specific touch coordinates and the second touch coordinates are two adjacent touch coordinates according to the second direction; and when the second determination distance is not greater than one At the second predetermined distance, the particular touch coordinates are discarded. The method of claim 8, further comprising: detecting a plurality of reference touch coordinates and recording each reference touch when a user places the palm in a writing state on a touch panel; a first reference coordinate value and a second reference coordinate value, wherein the first reference block The value is related to the first direction, and the second reference coordinate value is related to the second direction; and for each of the plurality of reference touch coordinates, the two adjacent reference touch coordinates are determined according to the first direction a plurality of first reference coordinate difference values; and for each of the plurality of reference reference touch coordinates in the plurality of reference touch coordinates, respectively determining a plurality of second reference coordinate difference values; A maximum first reference coordinate difference value of a reference coordinate difference value is set to the first predetermined distance; and a maximum second reference coordinate difference value of the plurality of second reference coordinate difference values is set to the first predetermined distance. The method of claim 1, further comprising: outputting the first coordinate value of the specific touch coordinate and the only one of the plurality of first determination distances when the specific first determination distance is greater than the first predetermined distance The second coordinate value. The method of claim 1, further comprising: determining the first predetermined distance according to a user's palm or writing habit.