TWI444878B - Surface capacitive touch panel and method for controlling the same - Google Patents

Description

Surface capacitive touch panel and control method thereof

The invention relates to a surface capacitive touch panel and a control method thereof, and in particular to a surface capacitive touch panel with multi-touch function and a control method thereof.

With the rapid development of technology, manufacturers of electronic devices such as notebook computers, mobile phones, and portable multimedia players have used touch panels to replace traditional keyboards as a new generation of input interfaces.

In the Republic of China Patent Publication No. M361674, a position sensing device is disclosed that senses the contact behavior of more than one object and outputs an inductive signal related to the position of the object. In the US Patent Publication No. 20100039405, a projected capacitive touch device is disclosed, which can detect the position of a multi-touch, which generates first and second reference values according to the first and second touch points, and filters the The fake touch points generated by the two touch points obtain the real first touch point and the second touch point. In the Republic of China Patent Publication No. 200937269, a device and method for determining the position of a multi-contact on a projected capacitive touch panel are disclosed. In the Republic of China Patent Publication No. 200842682, a digital controller that can use a true multi-point contact surface is disclosed. In the Republic of China Patent Publication No. 200847001, a method and system having a schematic action of a multi-point sensing device is disclosed that can detect multiple objects (eg, fingers) simultaneously or nearly simultaneously. In the Republic of China Patent Publication No. M368849, a multi-point capacitive touch sensor is disclosed. In the Republic of China Patent Publication No. 200938861, A capacitance detecting system, module and method are disclosed. In U.S. Patent Publication No. 201001258, an apparatus and method for determining the position of at least one object at a contact surface is disclosed. In U.S. Patent Publication No. 20090085894, a multi-touch screen having a transparent nanostructure film is disclosed, which can simultaneously accept multiple touches and analyze the multi-point data. In US Patent Publication No. 20070109280, a multi-touch device and method are disclosed, which compares whether the time difference between the first touch point and the second touch point is within a predetermined time to determine its actuation behavior. In US Patent Publication No. 20080150906, a multi-axial touch sensing device is disclosed that can analyze the position of a multi-touch. In the Republic of China patent 200933456, a touch panel capable of performing multi-object operations and an application method thereof are disclosed. In US Pat. No. 7,255,775, a system and method for distinguishing multi-finger simultaneous touches is disclosed to obtain the correct position of multi-finger touch. In addition, in the U.S. Patent No. 4,353,552, a single-touch surface capacitive touch panel is disclosed.

The invention provides a surface capacitive touch panel, which calculates the first touch position according to the current flowing through the four electrodes of the surface capacitive touch panel at the first time point, and according to the first time point to the second The second touch position is calculated by the amount of current change flowing through the above four electrodes during the time point.

The invention provides a method for controlling a surface capacitive touch panel, which calculates a first touch position and a second touch position according to currents flowing through four electrodes of the surface capacitive touch panel at two time points.

Other objects and advantages of the present invention will become apparent from the technical features disclosed herein.

In order to achieve one or a part or all of the above or other purposes, an embodiment of the present invention provides a surface capacitive touch panel. The surface capacitive touch panel includes a conductive film and a driving circuit. The driving circuit includes an analog digital converter and an arithmetic unit. The conductive film is provided with a first electrode, a second electrode, a third electrode, and a fourth electrode. The driving circuit is coupled to the first electrode, the second electrode, the third electrode and the fourth electrode for transmitting a first current flowing through the first electrode, a second current flowing through the second electrode, and flowing through the third electrode And a third current flowing through the fourth electrode. The analog digital converter is configured to convert the first current, the second current, the third current, and the fourth current into a first current value, a second current value, a third current value, and a fourth current value, respectively. The arithmetic unit is coupled to the analog digital converter, and is configured to calculate the first touch position according to the first current value, the second current value, the third current value, and the fourth current value at the first time point, and according to the first The second touch position is calculated by the amount of change of the current value, the second current value, the third current value, and the fourth current value during the first time point to the second time point.

An embodiment of the invention provides a method of controlling a surface capacitive touch panel. The method includes: first, second, third, and fourth currents flowing through the first electrode, the second electrode, the third electrode, and the fourth electrode of the surface capacitive touch panel by an analog digital converter The current is respectively converted into a first current value, a second current value, a third current value, and a fourth current value; the first current value, the second current value, the third current value, and the fourth current value according to the first time point Calculating the first touch position; The second touch position is calculated according to the amount of change of the first current value, the second current value, the third current value, and the fourth current value during the first time point to the second time point.

In an embodiment of the invention, the driving circuit further includes a memory unit for storing the first current value, the second current value, the third current value, and the fourth current value at the first time point. When at the second time point, the operation unit reads the first current value, the second current value, the third current value, and the fourth current value stored in the memory unit, and receives the second time point from the analog digital converter. The first current value, the second current value, the third current value, and the fourth current value are used to calculate the second touch position.

In an embodiment of the invention, the first current value, the second current value, the third current value, and the fourth current value are I _1t1 , I _2t1 , I _{3t1 ,} and I _4t1 at the first time points. A first current value, second current value, the current value of the third and the fourth current value at a second time point were _{I 1t2,} I _2t2, I 3t2 and _I 4t2, and the first touch position is equal to And the second touch position is equal to . Where Δ I _{1 t 2} = I _{1 t 2} - I _{1 t 1} , Δ I _{2 t 2} = I _{2 t 2} - I _{2 t 1} , Δ I _{3 t 2} = I _{3 t 2} - I _{3 t 1} , △ I _{4 t 2} = I _{4 t 2} - I _{4 t 1} .

In an embodiment of the present invention, the calculating unit calculates the amount of change of the first current value, the second current value, the third current value, and the fourth current value during the first time point to the third time point. The third touch position.

In an embodiment of the invention, the first current value, the second current value, the third current value, and the fourth current value are I _1t1 , I _2t1 , I _{3t1 ,} and I _4t1 at the first time points. A first current value, second current value, the current value of the third and the fourth current value at a second time point were _{I 1t2,} I _2t2, I 3t2 and _I 4t2. A first current value, second current value, the current value of the third and the fourth current value at a third time point were _{I 1t3,} I 2t3, I _3t3 and _I 4t3. The first touch position is equal to , the second touch position is equal to , the third touch position is equal to . Where Δ I _{1 t 2} = I _{1 t 2} - I _{1 t 1} , Δ I _{2 t 2} = I _{2 t 2} - I _{2 t 1} , Δ I _{3 t 2} = I _{3 t 2} - I _{3 t 1} , △ I _{4 t 2} = I _{4 t 2} - I _{4 t 1} , Δ I _{1 t 3} = I _{1 t 3} - I _{1 t 1} , Δ I _{2 t 3} = I _{2 t 3} - I _{2 t 1} , Δ I _{3 t 3} = I _{3 t 3} - I _{3 t 1} , Δ I _{4 t 3} = I _{4 t 3} - I _{4 t 1} .

In an embodiment of the invention, the computing unit enlarges, reduces, or rotates an object according to the first touch position, the second touch position, and the third touch position.

In the above embodiment of the present invention, the surface capacitive touch panel calculates the first touch position according to the current flowing through the four electrodes at the first time point, and according to the first time point to the second time point. The amount of current change flowing through the four electrodes calculates the second touch position, and the surface capacitive touch panel has a multi-touch function.

The above described features and advantages of the invention will be apparent from the following description.

The above and other technical contents, features and advantages of the present invention will be apparent from the following detailed description of the preferred embodiments. The directional terms mentioned in the following embodiments, such as up, down, left, right, front or back, etc., are only directions referring to the additional drawings. Therefore, the directional terminology used is for the purpose of illustration and not limitation.

The technical principle of a surface capacitive touch panel is to provide a voltage at four corners of a conductive plane (such as an indium tin oxide (ITO) film or glass) to make it in a conductive plane. A uniform electric field is formed. When a human finger touches the conductive plane, a current flows from the finger to generate a signal, and the current signal of the four corners can calculate the position where the finger touches.

Please refer to Figure 1 to Figure 3. 1 is a schematic view of a surface capacitive touch panel 100 according to an embodiment of the present invention, FIG. 2 is a top view of a panel body 200 of FIG. 1, and FIG. 3 is a functional block of the surface capacitive touch panel 100 of FIG. The surface capacitive touch panel 100 has a driving circuit 110 and a panel body 200. The panel body 200 has a substrate 202, a conductive film 204, and a protective film 206. In an embodiment of the present invention, the material of the substrate 202 is, for example, transparent glass, and the material of the conductive film 204 is, for example, indium tin oxide (ITO), and the material of the protective film 206 is, for example, silicon dioxide (silicon). Dioxide; SiO ₂ ), but the invention is not limited thereto. A panel capacitor is formed between the substrate 202 and the conductive film 204. For convenience of representation, the panel capacitance is denoted by Cp in FIG. The first electrode 210, the second electrode 220, the third electrode 230, and the fourth electrode 240 are disposed on the conductive film 204. As shown in FIG. 2, in the present embodiment, the first electrode 210, the second electrode 220, the third electrode 230, and the fourth electrode 240 are respectively disposed at four corners of the panel body 200. The driving circuit 110 is coupled to the first electrode 210, the second electrode 220, the third electrode 230, and the fourth electrode 240 to respectively transmit the first current I ₁ , the second current I ₂ , the third current I ₃ , and the fourth current I ₄ to the first electrode 210, the second electrode 220, the third electrode 230, and the fourth electrode 240. Since the human body is an electric conductor, when the human finger touches the conductive film 204, it is capacitively coupled with the electric field of the conductive film 204, and thus the capacitance value of the panel capacitance Cp changes. The first current I ₁ , the second current I ₂ , and the third current I ₃ flowing through the first electrode 210 , the second electrode 220 , the third electrode 230 , and the fourth electrode 240 due to a change in the capacitance value of the panel capacitor Cp The fourth current I ₄ will also change. The driving circuit 110 can calculate the coordinates of the corresponding touch point according to the changes of the first current I ₁ , the second current I ₂ , the third current I ₃ , and the fourth current I ₄ .

The drive circuit 110 has an analog digital converter 112 and an arithmetic unit 114. The analog-to-digital converter 112 is configured to convert the first current I ₁ , the second current I ₂ , the third current I ₃ , and the fourth current I ₄ into a first current value, a second current value, a third current value, and a first Four current values. The computing unit 114 is coupled to the analog-to-digital converter 112 for calculating the corresponding touch according to the first current value, the second current value, the third current value, and the fourth current value output by the analog-to-digital converter 112. position. In addition, in an embodiment of the invention, the driving circuit 110 further includes a memory unit 116 for temporarily storing information required by the computing unit 114. In the following description, the control method of the surface capacitive touch panel 100 will be described with reference to the drawings.

Please refer to FIG. 4 , which illustrates a situation in which the surface capacitive touch panel 100 of FIG. 1 is not touched by the panel body 200 . When the panel body 200 is not touched, the first current I ₁ , the second current I ₂ , the third current I ₃ , and the fourth current I ₄ are very small. In this embodiment, the first current I ₁ , the second current I ₂ , the third current I ₃ , and the fourth current I _{4 at this time} are respectively 10 microamperes (uA).

Please refer to FIG. 5. FIG. 5 is a schematic diagram of the surface capacitive touch panel 100 of FIG. 1 when the panel body 200 is touched by a finger of a user. At the first time point, since one finger of the user touches the panel body 200, the capacitance value of the panel capacitor Cp changes, and causes the first current I ₁ , the second current I ₂ , the third current I _{3 ,} and the fourth The current I ₄ changes. As shown in FIG 5, when the first current I _1, the second current I _2, I ₃ a third current and a fourth current I ₄ of 300 microamperes, 100 microamperes, 300 microamperes and 100 microamperes. The magnitudes of the first current I ₁ , the second current I ₂ , the third current I _{3 ,} and the fourth current I ₄ are related to the position at which the user touches the panel body 200. In other words, when the position of the panel body 200 is touched by the user, the magnitudes of the first current I ₁ , the second current I ₂ , the third current I _{3 ,} and the fourth current I ₄ are correspondingly changed. The analog-to-digital converter 112 converts the first current I ₁ , the second current I ₂ , the third current I _{3 ,} and the fourth current I ₄ into a first current value, a second current value, a third current value, and a fourth, respectively. Current value. Taking FIG. 5 as an example, at the first time point, the first current value, the second current value, the third current value, and the fourth current value are I _1t1 , I _2t1 , I _{3t1 ,} and I _{4t1 , respectively} . The operation unit 114 calculates the coordinates of the first touch position A according to the current value converted by the analog-to-digital converter 112. The coordinate is the origin of the upper left corner of the panel body 200. In addition, in an embodiment of the invention, the first current value I _1t1 , the second current value I _2t1 , the third current value I _{3t1 ,} and the fourth current value I _4t1 are stored in the memory unit 116 as the operation unit 114 . The basis for subsequent calculations.

Please refer to FIG. 6. FIG. 6 is a schematic diagram of the surface capacitive touch panel 100 of FIG. 1 when the panel body 200 is touched by two fingers of the user. At the second time point, the capacitance value of the panel capacitor Cp is changed due to the other finger of the user touching the second touch position B of the panel body 200, and the first current I ₁ and the second current I _{2 are} caused. The third current I ₃ and the fourth current I ₄ change. As shown in FIG. 6, the first current I ₁ , the second current I ₂ , the third current I _{3 ,} and the fourth current I _{4 at this time} are all 400 microamperes. It is noted that the sizes of the first current I ₁ , the second current I ₂ , the third current I _{3 ,} and the fourth current I ₄ are different from the first touch position A and the second touch position B on the panel body 200 . The coordinates are related, and the values of the above currents are only for illustrative purposes, and the invention should not be limited thereto.

At a second time point, the analog-to-digital converter 112 also converts the first current I ₁ , the second current I ₂ , the third current I _{3 ,} and the fourth current I ₄ into a first current value, a second current value, The third current value and the fourth current value. 6 as an example, at a second time point, the first current value, second current value, the current value of the third and fourth current values of _{I 1t2,} I _2t2, I 3t2 and _I 4t2. The operation unit 114 calculates the coordinates of the second touch position B according to the change amount of the first current value, the second current value, the third current value, and the fourth current value during the first time point to the second time point. Where Δ I _{1 t 2} = I _{1 t 2} - I _{1 t 1} , Δ I _{2 t 2} = I _{2 t 2} - I _{2 t 1} , Δ I _{3 t 2} = I _{3 t 2} - I _{3 t 1} , Δ I _{4 t 2} = I _{4 t 2} - I _{4 t 1} .

The user can zoom in, zoom out or rotate an object by moving the finger at the second touch position B. The above object is, for example, a picture or a window on a computer screen. Please refer to FIG. 6 and FIG. 7, wherein FIG. 7 illustrates the change of the two fingers of the user when the object is enlarged. At the third time point, the user's finger moves from the second touch position B to the third touch position B'. In this case, the first current value, second current value, the current value of the third and fourth current values of _{I 1t3,} I 2t3, I _3t3 and _I 4t3. The operation unit 114 calculates the coordinates of the third touch position B′ according to the change amount of the first current value, the second current value, the third current value, and the fourth current value during the first time point to the third time point. for Where Δ I _{1 t 3} = I _{1 t 3} - I _{1 t 1} , Δ I _{2 t 3} = I _{2 t 3} - I _{2 t 1} , Δ I _{3 t 3} = I _{3 t 3} - I _{3 t 1} , Δ I _{4 t 3} = I _{4 t 3} - I _{4 t 1} . Afterwards, the computing unit 114 further determines that the two fingers of the user are in the second time point to the third time point according to the coordinates of the first touch position A, the second touch position B, and the third touch position B′. The change period during the period to control the action of the above objects. Taking FIG. 7 as an example, since the horizontal distance between the two fingers of the user is increased and the vertical distance is substantially unchanged during the second time point to the third time point, the arithmetic unit 114 generates corresponding control. Signal to magnify the object.

In addition to zooming in on the object, you can also reduce and rotate the work of the object. can. Please refer to FIG. 8. FIG. 8 illustrates the change of the two fingers of the user when the object is reduced. Similarly, at the third time point, the user's finger moves from the second touch position B to the third touch position B'. During the period from the second time point to the third time point, the horizontal distance between the two fingers of the user is reduced and the vertical distance is substantially unchanged, so the operation unit 114 generates a corresponding control signal to reduce the object.

Please refer to FIG. 9. FIG. 9 illustrates the change of the two fingers of the user when the object is rotated. Similarly, at the third time point, the user's finger moves from the second touch position B to the third touch position B'. Because the trajectory of the finger from the second touch position B to the third touch position B′ is approximately curved in a period from the second time point to the third time point, the operation unit 114 generates a corresponding control signal to Rotate the object in the positive clock direction.

In summary, in the above embodiments of the present invention, at least one of the following advantages is obtained. The surface capacitive touch panel calculates the first touch position according to the current flowing through the four electrodes at the first time point, and The second touch position is calculated according to the amount of current change flowing through the four electrodes during the first time point to the second time point, so that the surface capacitive touch panel has the function of multi-touch. In addition, as the touch position of the user changes, the calculation unit of the surface capacitive touch panel generates a corresponding control signal to enlarge, reduce or rotate the object.

The above is only the preferred embodiment of the present invention, and the scope of the invention is not limited thereto, that is, the simple equivalent changes and modifications made by the scope of the invention and the description of the invention are All remain within the scope of the invention patent. In addition, any embodiment or patent application of the present invention It is not necessary to achieve all of the objects or advantages or features disclosed herein. In addition, the abstract sections and headings are only used to assist in the search of patent documents and are not intended to limit the scope of the invention.

100‧‧‧Surface capacitive touch panel

110‧‧‧Drive circuit

112‧‧‧ Analog Digital Converter

114‧‧‧ arithmetic unit

116‧‧‧ memory unit

200‧‧‧ Panel body

202‧‧‧Substrate

204‧‧‧Electrical film

206‧‧‧Protective film

210‧‧‧First electrode

220‧‧‧second electrode

230‧‧‧ third electrode

240‧‧‧fourth electrode

A‧‧‧First touch position

B‧‧‧second touch position

B’‧‧‧ third touch position

Cp‧‧‧ panel capacitor

GND‧‧‧ ground terminal

I ₁ ‧‧‧First current

I ₂ ‧‧‧second current

I ₃ ‧‧‧third current

I ₄ ‧‧‧fourth current

FIG. 1 is a schematic diagram of a surface capacitive touch panel according to an embodiment of the invention.

2 is a top view of a panel body of FIG. 1.

3 is a functional block of the surface capacitive touch panel of FIG. 1.

FIG. 4 is a schematic diagram of the surface capacitive touch panel of FIG. 1 when the panel body is not touched.

FIG. 5 is a schematic diagram of the surface capacitive touch panel of FIG. 1 when the panel body is touched by one finger of the user.

FIG. 6 is a schematic diagram of the surface capacitive touch panel of FIG. 1 when the panel body is touched by two fingers of the user.

Figure 7 illustrates the change in the user's two fingers when the object is enlarged.

Figure 8 illustrates the change in the user's two fingers when the object is reduced.

Figure 9 illustrates the change in the user's two fingers when the object is rotated.

110‧‧‧Drive circuit

112‧‧‧ Analog Digital Converter

114‧‧‧ arithmetic unit

116‧‧‧ memory unit

210‧‧‧First electrode

220‧‧‧second electrode

230‧‧‧ third electrode

240‧‧‧fourth electrode

A‧‧‧First touch position

B‧‧‧second touch position

Claims (11)

A surface capacitive touch panel includes: a conductive film, a first electrode, a second electrode, a third electrode, and a fourth electrode; and a driving circuit coupled to the first electrode, the first a second electrode, the third electrode and the fourth electrode for transmitting a first current flowing through the first electrode, a second current flowing through the second electrode, and a third flowing through the third electrode a current and a fourth current flowing through the fourth electrode, the driving circuit comprising: an analog-to-digital converter for converting the first current, the second current, the third current, and the fourth current into one a first current value, a second current value, a third current value, and a fourth current value; and an arithmetic unit coupled to the analog digital converter for the first time according to a first time point Calculating a first touch position according to the current value, the second current value, the third current value, and the fourth current value, and according to the first current value, the second current value, the third current value, and the The fourth current value is from the first time point to the second time Calculating a second touch position, wherein the first time point is when a touch point touches the surface capacitive touch panel, and the second time point is two touches When the handle touches the surface capacitive touch panel. The surface capacitive touch panel of claim 1, wherein the driving circuit further comprises a memory unit for storing in the first The first current value, the second current value, the third current value, and the fourth current value at a time point, and when at the second time point, the operation unit reads the one stored in the memory unit a first current value, the second current value, the third current value, and the fourth current value, and the first current value, the second current value, and the second current value received at the second time point from the analog-to-digital converter The third current value and the fourth current value are used to calculate the second touch position. The surface capacitive touch panel of claim 1, wherein the first current value, the second current value, the third current value, and the fourth current value are respectively I at the first time point. _1t1, I _2t1, I _3t1 and I _4t1, the first current value, the second current value, the current value and the third current value at a fourth point in time are the second _{I 1t2,} I _2t2, I 3t2 And I _4t2 , and the first touch position is equal to , the second touch position is equal to Where Δ I _{1 t 2} = I _{1 t 2} - I _{1 t 1} , Δ I _{2 t 2} = I _{2 t 2} - I _{2 t 1} , Δ I _{3 t 2} = I _{3 t 2} - I _{3 t 1} , Δ I _{4 t 2} = I _{4 t 2} - I _{4 t 1} . The surface capacitive touch panel of claim 1, wherein the operation unit is based on the first current value, the second current value, the third current value, and the fourth current value at the first time A third touch position is calculated by the amount of change from the point to the third time point. The surface capacitive touch panel of claim 4, wherein the first current value, the second current value, the third current value, and the fourth current value are respectively I at the first time point. _1t1, I _2t1, I _3t1 and I _4t1, the first current value, the second current value, the current value and the third current value at a fourth point in time are the second _{I 1t2,} I _2t2, I 3t2 and _I 4t2, the first current value, the second current value, the third current value and the current value of the fourth point to the third time was _I 1t3, I _3t3, I _3t3 and _I 4t3, and the second One touch position is equal to , the second touch position is equal to The third touch position is equal to Where Δ I _{1 t 2} = I _{1 t 2} - I _{1 t 1} , Δ I _{2 t 2} = I _{2 t 2} - I _{2 t 1} , Δ I _{3 t 2} = I _{3 t 2} - I _{3 t 1} , Δ I _{4 t 2} = I _{4 t 2} - I _{4 t 1} , Δ I _{1 t 3} = I _{1 t 3} - I _{1 t 1} , Δ I _{2 t 3} = I _{2 t 3} - I _{2 t 1} , Δ I _{3 t 3 = I 3 t 3} - I 3 t 1, △ I 4 t 3 = I 4 t 3 - I 4 t 1. The surface capacitive touch panel of claim 4, wherein the computing unit enlarges, reduces or rotates an object according to the first touch position, the second touch position, and the third touch position. . A method for controlling a surface capacitive touch panel includes: passing a first electrode, a second electrode, a third electrode, and a fourth through the surface capacitive touch panel by an analog-to-digital converter a first current, a second current, a third current, and a fourth current of the electrode are respectively converted into a first current value, a second current value, a third current value, and a fourth current value; Calculating a first touch position by the first current value, the second current value, the third current value, and the fourth current value at a first time point And calculating a second according to the first current value, the second current value, the third current value, and the amount of change of the fourth current value during the first time point to a second time point a touch position, wherein the first time point is when a touch point touches the surface capacitive touch panel, and the second time point is when the two touch points touch the surface capacitive touch panel . The method of claim 7, wherein the first current value, the second current value, the third current value, and the fourth current value are I _1t1 and I _2t1 at the first time point, respectively. I _3t1 and I _4t1, the first current value, the second current value, the current value and the third current value at a fourth point of the second time was _{I 1t2,} I _2t2, I 3t2 and _I 4t2, and The first touch position is equal to , the second touch position is equal to Where Δ I _{1 t 2} = I _{1 t 2} - I _{1 t 1} , Δ I _{2 t 2} = I _{2 t 2 -} I _{2 t 1} , Δ I _{3 t 2} = I _{3 t 2} - I _{3 t 1} , Δ I _{4 t 2} = I _{4 t 2} - I _{4 t 1} . The method of claim 7, further comprising: determining, according to the first current value, the second current value, the third current value, and the fourth current value, the first time to the third time A third touch position is calculated by the amount of change during the period. The method of claim 9, wherein the first current value, the second current value, the third current value, and the fourth current value are I _1t1 and I _2t1 at the first time point, respectively. I _3t1 and I _4t1, the first current value, the second current value, the current value and the third current value at a fourth point of the second time was _{I 1t2,} I _2t2, I 3t2 and _I 4t2, the a first current value, the second current value, the third current value and the current value of the fourth point to the third time was _{I 1t3,} I 2t3, I _3t3 and _I 4t3, and the first touch position is equal to , the second touch position is equal to The third touch position is equal to Where Δ I _{1 t 2} = I _{1 t 2} - I _{1 t 1} , Δ I _{2 t 2} = I _{2 t 2} - I _{2 t 1} , Δ I _{3 t 2} = I _{3 t 2} - I _{3 t 1} , Δ I _{4 t 2} = I _{4 t 2} - I _{4 t 1} , Δ I _{1 t 3} = I _{1 t 3} - I _{1 t 1} , Δ I _{2 t 3} = I _{2 t 3} - I _{2 t 1} , Δ I _{3 t 3} = I _{3 t 3} - I _{3 t 1} , Δ I _{4 t 3} = I _{4 t 3} - I _{4 t 1} . The method of claim 9, further comprising: zooming in, reducing or rotating an object according to the first touch position, the second touch position, and the third touch position.