TWI397005B - Ghost Detection Method for Capacitive Touchpad - Google Patents

Description

Ghost detection method for capacitive touch panel

The present invention relates to a capacitive touch panel, and more particularly to a ghost detection method for a capacitive touch panel.

A capacitive touch panel that is programmed in the XY direction produces a ghost phenomenon when multi-finger input is performed. Figure 1 is a schematic diagram of ghosting phenomenon, when the position of the user's two fingers on the capacitive touch panel is left lower right (as shown in the left of Figure 1), or left upper right and lower right (as shown in the right of Figure 1) The X-direction capacitance value change waveform and the Y-direction capacitance value change waveform detected by the capacitive touch panel are the same, so the control circuit cannot determine the true contact position.

In the two-finger input state, there are two possible coordinates when ghosting occurs, as shown in Figure 2. When the ghost phenomenon occurs, the capacitance value in the X direction changes at the traces x ₁ and x ₂ , and the capacitance value in the Y direction increases at the traces y ₁ and y ₂ , excluding the same X or Y coordinates. After the permutation and combination, the possible finger coordinates are (x ₁ y ₁ , x ₂ y ₂ ) and (x ₁ y ₂ , x ₂ y ₁ ), one of which is the actual coordinate and the other is the ghost. coordinate. When more fingers are input, the number of ghost coordinates will increase rapidly, as shown in Figure 3. For three-finger input, the possible finger coordinates are (x ₁ y ₁ , x ₂ y ₂ , x ₃ y ₃ ), (x ₁ y ₁ , x ₂ y ₃ , x ₃ y ₂ ), (x _l y ₂ , x ₂ y ₁ , x ₃ y ₃ ), (x ₁ y ₂ , x ₂ y ₃ , x ₃ y ₁ ) , (x ₁ y ₃ , x ₂ y ₂ , x ₃ y ₁ ), (x ₁ y ₃ , x ₂ y ₁ , x ₃ y ₂ ), six groups, of which five groups are ghost coordinates.

One of the objects of the present invention is to provide a ghost detection method for a capacitive touch panel.

According to the present invention, a ghost detection method for a capacitive touch panel is detected when a user touches the capacitive touch panel to cause a ghost phenomenon in the first position and the second position, the first position And the second location has the same first direction coordinate, the detecting method includes simultaneously charging the first direction trace and the second direction trace of the first location to obtain the first or second direction of the first location a trace capacitance value, the first direction trace and the second direction trace of the second position are simultaneously charged, obtaining a first or second direction trace capacitance value of the second position, and according to the first position The one or second direction trace capacitance value and the first or second direction trace capacitance value of the second position determine the position where the user actually touches.

According to the present invention, a ghost detection method for a capacitive touch panel is detected when a user touches the capacitive touch panel to cause a ghost phenomenon in the first position and the second position, the first position And the second position has the same first direction coordinate, the detecting method includes simultaneously charging the first direction trace and the second direction trace of the first position, and obtaining the first and second directions of the first position. a trace capacitance value, summing the first and second direction trace capacitance values of the first position to obtain a first total capacitance value, and simultaneously charging the first direction trace and the second direction trace of the second position Obtaining the first and second direction trace capacitance values of the second position, summing the first and second direction trace capacitance values of the second position, obtaining a second total capacitance value, and according to the first total The combined capacitance value and the second total combined capacitance value determine the position where the user actually touches.

According to the present invention, a ghost detection method for a capacitive touch panel is detected when a user touches the capacitive touch panel to cause a ghost phenomenon in the first position and the second position, the first position And the second location has the same first direction coordinate, the detecting method includes charging the first and second direction traces of the first location, detecting the first direction trace of the first location to obtain the first a capacitance value, the first direction trace of the first position is charged, and the second direction trace of the first position is grounded, and the first direction trace of the first position is detected to obtain a second capacitance value, The first capacitance value is subtracted from the second capacitance value to obtain a first capacitance difference value, and the first and second direction traces of the second position are charged, and the first direction trace of the second position is detected to obtain a third capacitance value, the first direction trace of the second position is charged, and the second direction trace of the second position is grounded, and the first direction trace of the second position is detected to obtain a fourth capacitance value, Subtracting the third capacitance value from the fourth capacitance value to obtain a second capacitance difference The difference between the first capacitor and the second capacitor and a difference, the user determines the actual contact position.

By comparing the obtained capacitance values, the ghost detection method of the present invention can quickly and accurately locate the actual contact position when the ghost phenomenon occurs, and provide the XY coordinates required for precise positioning.

4 is a schematic view of a first embodiment of the present invention, the coordinates of the finger 12 are represented by x _m y _k , the coordinates of the finger 14 are represented by x _n y _l , and the fingers 12 and 14 cause capacitance changes on the capacitive touch panel. The values appear peak at positions x _m y _l , x _m y _k , x _n y _{l ,} and x _n y _k , causing ghosting, and the control circuit cannot distinguish whether the finger 12 is located at x _m y _l or x _m y _k . It is also impossible to judge whether the finger 14 is located at x _n y _l or x _n y _k , at which time two sets of ghost candidate coordinates (x _m y _l , x _n y _k ) and (x _m y _k , x _n y _l ) appear. The positions x _m y _l , x _m y _k , x _n y _l and x _n y _k are ghost candidate positions. The present invention proposes a ghost detection method. When a ghost phenomenon occurs, a position where each peak appears one by one, that is, X and Y direction traces at each ghost candidate position are simultaneously charged and capacitance value detection is performed. When the time of (x _m y _k) for detecting the position 16 under test, the switches S1 and S3 are closed, the controller (not shown) while the traces x _m and y _k charging traces acquired x _m and y _k The value of the capacitor. The capacitance value Cx on the trace x _m is Cx _m + Cx _m y _l + dCx _m + Cx _m y _k , dCx _m represents the change in capacitance of the trace x _m due to the proximity of the finger 12, and Cx _m represents the other ground trace and The sum of the capacitance values between the ground and the trace x _m , Cx _m y _l represents the capacitance between the trace x _m and the trace y _l , and Cx _m y _k represents the capacitance between the trace x _m and the trace y _k Where, because the trace x _m and the trace y _k are equipotential, the magnitude of Cx _m y _k is zero. Since the measured position 16 is the position where the finger 12 actually contacts, the capacitance value C _x measured from the trace x _m is equal to the actual position capacitance value Cr _x = Cx _m + Cx _m y _l + dCx _m . Traces in the Y direction y _k traces measured capacitance value C _y also because the actual contact position of the finger 12 in x _m y _k, the measured capacitance value of an amount of the actual position value of the capacitance Cr _y = Cy _k + Cx _n y _k +dCy _k .

FIG. 5 is a schematic diagram showing when the actual contact position of the finger 12 is at x _m y _l and the measured position 16 is a ghost position, and the controller simultaneously charges the trace x _m and the trace y _k at the same time, the traces x _m and y _{k is} equipotential, so the measured value of Cx _m y _k is zero, but the finger 12 at x _m y _l causes a capacitance change dCx _m y _l between the trace y _l and the trace x _m , dCx _m y _l is a negative value, the capacitance value of x at this time traces on C _x is equal to the sum of _m ghost position capacitance value _{Cg x = Cx m + Cx m} y l + dCx m y l + dCx m. Trace y _k from the measured capacitance value C _y Y direction as the finger 14 in x _n y _k, resulting in a negative change in capacitance between the dCx _n y _k x _n traces and y _k, and therefore the capacitance value measured C _y is the ghost position capacitance value Cg _y =Cy _k +Cx _n y ₁ +dCx _n y _k +dCy _k .

The X-direction capacitance value and the Y-direction capacitance value obtained in FIG. 4 and FIG. 5 are compared with each other. Since dCx _m y _l is a negative value, the X-direction capacitance value measured at the actual position is Cr _x = Cx _m + Cx _m y _l + dCx _The value of the X-direction capacitance measured by _m larger than the ghost position is Cg _x = Cx _m + Cx _m y _l + dCx _m y _l + dCx _m , and similarly, since dCx _n y _k is a negative value, the Y measured at the actual position The direction capacitance value Cr _y =Cy _k +Cx _n y _k +dCy _{k is} also larger than the Y-direction capacitance value Cg _y =Cy _k +Cx _n y _k +dCx _n y _k +dCy _k measured at the ghost position. In short, after the above-mentioned XY traces are simultaneously charged and the capacitance values in the X and Y directions are obtained, the capacitance values obtained from the two points are compared, and the actual contact position can be distinguished.

6 and FIG. 7 are another embodiment of the ghost detection method of the present invention, connecting the X-direction trace and the Y-direction trace of the measured position to directly obtain the X-direction trace capacitance value of the measured position and The sum of the capacitance values of the Y-direction traces. As shown in FIG. 6, when the measured position 16 is the actual position of the finger 12, the measured capacitance value C _xy is the actual position capacitance value Cr _xy = Cx _m + Cy _k + Cx _m y _l + Cx _n y _k + dCx _m +dCy _k , referring to FIG. 7, when the measured position 16 is not the actual position of the finger, the measured capacitance value C _xy is the ghost position capacitance value Cg _xy = Cx _m + Cy _k + Cx _m y _l + Cx _n y _k +dCx _m +dCy _k +dCx _m y _l +dCx _n y _k , where dCx _m y _l and dCx _n y _k are negative values. Although the ghost phenomenon caused by two-finger touch has four ghost candidate positions, since the first actual position is determined, the ghost candidate position with the same X or Y coordinate as the actual position cannot be the second. Actual position, so when detecting the ghost phenomenon caused by two-finger touch, only two ghost candidate positions with the same X or Y coordinates need to be compared once to know the coordinates of the actual position.

When the ghosting phenomenon caused by the three-finger touch is processed by the foregoing detection method, the ghost candidate positions are nine points. Referring to FIG. 3, among the ghost candidate positions, the positions having the same X coordinate each have three points, first Test two points (x ₁ , y ₁ ) and (x ₁ , y ₂ ) with the same X coordinate as an example. If the capacitance values obtained by the test are equal, it means (x ₁ , y ₁ ) and (x ₁ , y ₂ ) The two points are all ghost positions, and the remaining X coordinates (x ₁ , y ₃ ) with the same two points are the actual positions; if the capacitance values obtained by the test are not equal, the capacitance value is larger, the point is the actual position. Therefore, it is only necessary to detect once to determine the first actual position. After determining the first actual position, for example, determining (x ₁ , y ₃ ) as the actual position, other ghost candidate positions having the same X coordinate or Y coordinate as (x ₁ , y ₃ ) can be known (x ₁ , y ₁ ), (x ₁ , y ₂ ), (x ₂ , y ₃ ), and (x ₃ , y ₃ ) are necessarily ghost positions, so the ghost positions can be directly excluded, and then the ghosts are Shadow candidate positions (x ₂ , y ₂ ), (x ₂ , y ₁ ) are ghost detected, and after determining the second actual position, ghost candidates having the same X or Y coordinates as the second actual position are deleted. The position can be used to obtain the last actual position. In other words, even in the ghost phenomenon caused by the three fingers, the detection method proposed by the present invention only needs to perform two comparisons to determine the actual finger coordinates. In other embodiments, each ghost candidate point may be detected one by one, and the trace capacitance value of each ghost candidate point is obtained, and then the firmware determines the trace capacitance values to improve the reliability.

FIG 8 is schematic view showing two intersecting trace capacitance, Cx _m herein denotes the trace capacitance value x _m of the ground, Cy _n y _n represents the trace capacitance value of the ground, Cx _m y _n x _m denotes the trace and The value of the coupling capacitance between the traces y _n , when the finger touches the junction of the traces x _m and y _n , the capacitance value Cx _m y _n will drop, and the present invention proposes a direct detection trace x _m and a trace y _n A method of capacitance between Cx _m y _n to distinguish ghost locations from actual contact locations. First, the traces x _m and y _{n are} simultaneously charged, and the capacitance value on the trace x _m is detected. At this time, the potentials of the traces x _m and y _n are measured, and the measured value of Cx _m y _n is zero. The capacitance value is the capacitance value Cx _m of the trace x _m to ground; then the trace x _{m is} charged and the trace y _{n is} grounded, at which time the traces x _m and y _{n are} not equipotential, thus detecting the trace the resulting x _m capacitance value Cx _m + Cx _m y _n, can be obtained by subtracting the two values of the coupling capacitance Cx _m y _n x _m between traces and y _n.

FIG. 9 and FIG. 10 are schematic diagrams showing an embodiment of detecting a capacitance value between two traces, FIG. 9 is a view showing a state when the measured position 16 is the actual position of the finger 12, and FIG. 10 is a diagram showing the measured position 16 as a ghost. The situation at the time of location. As shown in FIG. 9, when the measured position 16 is the actual position of the finger 12, the traces x _m and y _{k are first} charged simultaneously in phase 1, and the capacitance value Cx=Cx _m obtained by detecting the trace x _{m is} detected; Next, the trace x _{m is} charged in phase 2 and the trace y _{k is} grounded to obtain the capacitance value Cx=Cx _m +Cx _m y _k +dCx _m y _k on the trace x _m ; the capacitance obtained in phase 2 The capacitance difference ΔC _x obtained by subtracting the value from the capacitance value obtained by phase 1 is the actual position capacitance difference ΔCr _x = Cx _m y _k + dCx _m y _k . When the measured position 16 is a ghost position, as shown in FIG. 10, the detected position 16 is detected as described above, and the obtained capacitance difference ΔC _x is a ghost position capacitance difference ΔCg _x = Cx _m y _k , wherein , dCx _m y _{k is} less than zero, so the determination of the actual finger position can be achieved by comparing the capacitance difference ΔC _x .

The embodiments of the present invention implement the foregoing operations with firmware, and in other embodiments, errors caused by fingers, traces, and the like can be added to the operation.

11 is a flow chart of an embodiment of a touch panel control method according to the present invention. After starting 200, an X-direction trace detection 201 is performed first, followed by a Y-direction trace detection 202 to determine whether a ghost occurs 203. If not, the detection result is output and ends 204. In step 203, if ghosting is found, the ghost processing program is entered, firstly a ghost candidate list 205 is generated, all ghost candidate points are added to the ghost candidate list, and then the ghost image is extracted from step 206. A ghost candidate point is taken from the candidate list, and it is determined whether the point is the last point 207 of the ghost candidate list, and if so, the answer list 208 is output, and if not, the ghost analysis sensing 209 is performed. The steps of ghost analysis 209 are as described above, and the X-direction trace capacitance value, the Y-direction trace capacitance value, the summed capacitance value or the X and Y directions of the measured point are obtained. The capacitance value is compared with the capacitance value obtained from other candidate points to determine whether the measured point is a ghost point 210, and if so, the measured point 211 is removed from the ghost candidate list, and the step is returned. 206. Continue to detect and determine other candidate points. If no, indicating that the measured point is an actual location, the measured point is added to the answer list 212, and the point is removed from the ghost candidate list and The candidate points 231 with the same X or Y coordinates are clicked, and then back to step 206 to continue to detect other candidate points in the ghost candidate list, and finally the answer list 208 is output, ending 204. In this embodiment, the position of each ghost candidate point is represented by an XY coordinate, so the final output solution list already contains the XY coordinates of the solution point, which can provide accurate contact point positioning capability.

The above description of the preferred embodiments of the present invention is intended to be illustrative, and is not intended to limit the scope of the invention to the disclosed embodiments. It is possible to make modifications or variations based on the above teachings or learning from the embodiments of the present invention. The embodiments are described and illustrated in the practical application of the present invention in various embodiments, and the technical idea of the present invention is intended to be equivalent to the scope of the following claims. Decide.

12. . . finger

14. . . finger

16. . . Tested position

200. . . Start

201. . . X direction trace detection

202. . . Y direction trace detection

203. . . Ghosting happens?

204. . . End

205. . . Generate ghost candidate list

206. . . Take a little from the list of ghost candidates

207. . . Is this the last point in the list of ghost candidates?

208. . . Output answer list

209. . . Ghost analysis

210. . . This point is a ghost point

211. . . Remove the point from the ghost candidate list

212. . . Add this point to the answer list

231. . . Remove candidate points with the same X or Y coordinates from the ghost candidate list

Figure 1 is a schematic diagram of ghosting phenomenon;

2 is a schematic diagram of a ghost phenomenon caused by two-finger touch;

FIG. 3 is a schematic diagram of a ghost phenomenon caused by three-finger touch;

4 and 5 are schematic views of an embodiment of the present invention;

6 and 7 are schematic views of another embodiment of the present invention;

Figure 8 is a schematic diagram of capacitance on a two-phase intersection trace;

9 and 10 are schematic diagrams showing an embodiment of detecting a capacitance value between two traces;

11 is a flow chart of an embodiment of the present invention.

12. . . finger

14. . . finger

16. . . Tested position

Claims (20)

A ghost detection method for a capacitive touch panel, wherein the first position and the second position on the capacitive touch panel are ghost candidate positions, and the first position and the second position have the same first direction Coordinates, the detecting method includes the following steps: (A) simultaneously charging the first direction trace and the second direction trace of the first position; (B) obtaining the first or second direction trace of the first position a capacitance value; (C) simultaneously charging the first direction trace and the second direction trace of the second position; (D) obtaining a first or second direction trace capacitance value of the second position; and (E) Comparing a first direction trace capacitance value of the first location with a first direction trace capacitance value of the second location or comparing a second direction trace capacitance value of the first location with a second direction trace of the second location The line capacitance value determines the actual contact position. The ghost detection method of claim 1, wherein the step E includes: if the first or second direction trace capacitance value of the first location is greater than the first or second direction trace capacitance value of the second location, determining The first position is an actual contact position; and if the first or second direction trace capacitance value of the first position is less than the first or second direction trace capacitance value of the second position, determining the second position is actual Contact location. The ghost detection method of claim 2, further comprising adding the first location and the second location to the ghost candidate list. The ghost detection method of claim 3, further comprising removing the location of the judgment completion from the ghost candidate list. The ghost detection method of claim 4, further comprising removing a location having the same first or second direction coordinate from the actual contact location from the ghost candidate list. The ghost detection method of claim 1, wherein the step E comprises: If the first or second direction trace capacitance value of the first location is greater than the first or second direction trace capacitance value of the second location, determining that the first location is an actual contact location; if the first location is The first or second direction trace capacitance value is less than the first or second direction trace capacitance value of the second position, determining that the second position is an actual contact position; and if the first position is the first or second direction trace The line capacitance value is equal to the first or second direction trace capacitance value of the second position, and the first position and the second position are determined to be ghost locations. A ghost detection method for a capacitive touch panel, wherein the first position and the second position on the capacitive touch panel are ghost candidate positions, and the first position and the second position have the same first direction Coordinates, the detecting method includes the following steps: (A) simultaneously charging the first direction trace and the second direction trace of the first position; (B) obtaining the first and second direction traces of the first position a capacitance value; (C) summing the first and second direction trace capacitance values of the first position to generate a first total capacitance value; (D) a first direction trace and a second direction to the second position The traces are simultaneously charged; (E) the first and second direction trace capacitance values of the second position are obtained; (F) the first and second direction trace capacitance values of the second position are summed to generate a second total And (G) comparing the first total capacitance value and the second total capacitance value to determine an actual contact position. The ghost detection method of claim 7, wherein the step G includes: if the first total capacitance value is greater than the second total capacitance value, determining that the first position is an actual contact position; If the first total capacitance value is less than the second total capacitance value, it is determined that the second position is an actual contact position. The ghost detection method of claim 8, further comprising adding the first location and the second location to the ghost candidate list. The ghost detection method of claim 9, further comprising removing the location of the judgment completion from the ghost candidate list. The ghost detection method of claim 10, further comprising removing a location having the same first or second direction coordinate from the actual contact location from the ghost candidate list. The ghost detection method of claim 7, wherein the step G includes: if the first total capacitance value is greater than the second total capacitance value, determining that the first position is an actual contact position; if the first total capacitance is The value is less than the second total capacitance value, determining that the second position is an actual contact position; and if the first total capacitance value is equal to the second total capacitance value, determining that the first position and the second position are Ghost location. A ghost detection method for a capacitive touch panel, wherein the first position and the second position on the capacitive touch panel are ghost candidate positions, and the first position and the second position have the same first direction Coordinates, the detecting method includes the following steps: (A) charging the first and second direction traces of the first position, detecting a first direction trace of the first position to obtain a first capacitance value; (B Charging the first direction trace of the first location and grounding the second direction trace of the first location, detecting a first direction trace of the first location to obtain a second capacitance value; (C) The first capacitance value is subtracted from the second capacitance value to obtain a first capacitance difference value; (D) charging the first and second direction traces of the second location, detecting a first direction trace of the second location to obtain a third capacitance value; (E) a first direction of the second location Charging the trace and grounding the second direction trace of the second location to detect the first direction trace of the second location to obtain a fourth capacitance value; (F) the third capacitor value and the fourth capacitor The values are subtracted to obtain a second capacitance difference; and (G) comparing the first capacitance difference and the second capacitance difference to determine an actual contact position. The ghost detection method of claim 13, wherein the step G comprises: if the first capacitance difference is smaller than the second capacitance difference, determining that the first position is an actual contact position, and the second position is a ghost position; And if the first capacitance difference is greater than the second capacitance difference, determining that the second position is an actual contact position, the first position being a ghost position. The ghost detection method of claim 14, further comprising adding the first location and the second location to the ghost candidate list. The ghost detection method of claim 15 further includes removing the location of the judgment completion from the ghost candidate list. The ghost detection method of claim 16, further comprising removing a location having the same first or second direction coordinate from the actual contact location from the ghost candidate list. The ghost detection method of claim 13, wherein the step G comprises: if the first capacitance difference is smaller than the second capacitance difference, determining that the first position is an actual contact position, and the second position is a ghost position; If the first capacitance difference is greater than the second capacitance difference, determining that the second position is true The first contact position is a ghost position; and if the first capacitance difference is equal to the second capacitance difference, determining that the first position and the second position are ghost positions. A method for detecting a capacitive touch panel includes the steps of: detecting a first capacitance value and a second trace and a ground end between a first trace and a ground end in a first direction of the capacitive touch panel Between the second capacitance value; detecting a third capacitance value between the third trace and the ground end in the second direction of the capacitive touch panel and a fourth capacitance value between the fourth trace and the ground end Detecting a fifth capacitance value between the first trace and the third trace; detecting a sixth capacitance value between the second trace and the fourth trace; and according to the first, second, The third, fourth, fifth, and sixth capacitance values determine whether an object touches the capacitive touch panel. The method of detecting the item 19 further includes determining, according to the first, second, third, fourth, fifth, and sixth capacitance values, a contact position of the object touching the capacitive touch panel.