This Non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 099141663 filed in Taiwan, Republic of China on Dec. 1, 2010, the entire contents of which are hereby incorporated by reference.
1. Field of Invention
The present invention relates to a touch apparatus and, in particular, to a capacitive touch apparatus.
2. Related Art
The touch panels are easily operated, so they are applied to various kinds of electronic products, such as mobile communication, consumer electronic devices, to replace the traditional buttons. In these electronic products, the display panel and the touch panel, which is used as the input device, are combined, so that the electronic products become more valuable.
Since the capacitor Cp is electrically connected to the power signal VDD through the reset switch 11, the power signal VDD can charge the capacitor Cp and then the reset switch 11 is switched to discharge the capacitor Cp for charging the capacitor Csum. Accordingly, the electricity of the capacitor Cp can be transferred to the capacitor Csum. During the operation of the capacitive touch apparatus 1, the above-mentioned charging and discharging procedures of the capacitor Cp are repeatedly performed. When a finger touches the touch panel, the voltage of the capacitor Cp is increased. Then, when the reset switch 11 is switched, the voltage of the capacitor Csum is accordingly increased. The ranges of the above increases of the voltage are determined according to the ratio of the capacities of the capacitor Cp and the capacitor Csum. In this case, the variation of the capacitor Cp can be obtained by measuring the time period that the voltages exceed a constant voltage. After the measurement, the reset switch 12 is switched to discharge the capacitor Csum so as to allow the capacitor Csum to return its initial state. Following the above-mentioned steps, the touch operation can be detected.
However, because the capacitive touch apparatus 1 needs the charging and discharging procedures of two capacitors for detecting the touch operation, it spends more time in the detecting so that the response time of the capacitive touch apparatus 1 is slower. In addition, the conventional capacitive touch apparatus usually uses the detecting circuit with single end sensing wire, so it can not obtain the absolute coordinates of the touch position. Therefore, it is an important subject to provide a capacitive touch apparatus that can improve the sensing speed and is capable of obtaining the absolute coordinates of the touch position by the simple circuit design.
In view of the foregoing subject, an object of the present invention is to provide a capacitive touch apparatus that can improve the sensing speed by the simple circuit design.
To achieve the above object, the present invention discloses a capacitive touch apparatus including a first touch unit, a first voltage difference retrieving unit and a first feedback signal generating unit. The first touch unit includes a first conductive layer. The first voltage difference retrieving unit is electrically connected with one end of the first conductive layer and outputs a first voltage signal and a second voltage signal. The first feedback signal generating unit is electrically connected with the first voltage difference retrieving unit, and outputs a first feedback signal according to the variation of the voltage difference between the first voltage signal and the second voltage signal for computing a touch position.
In one embodiment of the present invention, the capacitive touch apparatus further includes a control unit electrically connected with the first voltage difference retrieving unit and the first feedback signal generating unit, wherein the control unit receives the first feedback signal for computing the touch position and outputs a power signal to the first voltage difference retrieving unit.
In one embodiment of the present invention, the first touch unit further includes a second conductive layer disposed above or below the first conductive layer.
In one embodiment of the present invention, the first and second conductive layers respectively comprise a plurality of sensing conductive bars.
In one embodiment of the present invention, each of the sensing conductive bars comprises a plurality of sensing electrodes connected in series, and the sensing electrode of each of the sensing conductive bars is rhombic, square, circular or irregular.
In one embodiment of the present invention, the sensing conductive bars of the first and second conductive layers are extended in perpendicular and not electrically connected with each other, and one end of the sensing conductive bars of the first and second conductive layers are electrically connected with the first voltage difference retrieving unit.
In one embodiment of the present invention, the first voltage difference retrieving unit comprises a first voltage-drop device, a first retrieving device and a second retrieving device, the first voltage-drop device is connected with the first touch unit, a power signal is provided through the first voltage-drop device to the first touch unit, and the first retrieving device connects to one end of the first voltage-drop device and outputs the first voltage signal, and the second retrieving device connects to the other end of the first voltage-drop device and outputs the second voltage signal.
In one embodiment of the present invention, each of the first retrieving device and the second retrieving device is a voltage follower.
In one embodiment of the present invention, the first feedback signal generating unit comprises an operation device for receiving the first voltage signal and the second voltage signal, and the operation device is a differential amplifier.
In one embodiment of the present invention, the power signal is a sine-wave power signal.
In one embodiment of the present invention, the control unit includes a microcontroller and a waveform modulator, the microprocessor outputs a square-wave voltage signal to the waveform modulator, and the waveform modulator outputs the sine-wave power signal.
In one embodiment of the present invention, the capacitive touch apparatus further includes a first selection unit electrically connected with the first touch unit and the first voltage difference retrieving unit.
In one embodiment of the present invention, the first selection unit includes at least one multiplexer and a plurality of resistors, one end of the multiplexer and one end of each of the resistors are electrically connected with the first touch unit, and the other end of the multiplexer is electrically connected with the first voltage difference retrieving unit.
In one embodiment of the present invention, the resistance value of the resistor of the first selection unit is much greater than that of the first voltage-drop device.
In one embodiment of the present invention, the capacitive touch apparatus further includes a second voltage difference retrieving unit and a second feedback signal generating unit. The second voltage difference retrieving unit is electrically connected with the other end of the first conductive layer and includes a second voltage-drop device, a third retrieving device and a fourth retrieving device, wherein the third retrieving device connects to one end of the second voltage-drop device and outputs a third voltage signal, and the fourth retrieving device connects to the other end of the second voltage-drop device and outputs a fourth voltage signal. The second feedback signal generating unit includes an operation device and receives the third voltage signal and the fourth voltage signal, and outputs a second feedback signal to the control unit according to the voltage difference between the third voltage signal and the fourth voltage signal.
In one embodiment of the present invention, the capacitive touch apparatus further includes a second touch unit electrically connected with the first touch unit.
In one embodiment of the present invention, one end of the second touch unit, which is not connected with the first touch unit, is electrically connected with the first voltage difference retrieving unit.
In one embodiment of the present invention, the capacitive touch apparatus further includes a third touch unit electrically connected with the first touch unit, and one end of the third touch unit is electrically connected with the second voltage difference retrieving unit.
As mentioned above, the capacitive touch apparatus of the present invention is configured with a first selection unit with a multiplexer for switching the connections between the first voltage difference retrieving unit and a plurality of sensing conductive bars of the first touch unit. In addition, the first voltage difference retrieving unit includes a first retrieving device and a second retrieving device for respectively retrieving the voltages of two ends of the voltage-drop device so as to determine the touch position and touch time. Furthermore, the capacitive touch apparatus of the present invention further includes a second touch unit, which is electrically connected with the first touch unit, without increasing complex connections and detecting the touch position. Accordingly, the capacitive touch apparatus of the present invention can improve the sensing speed and reduce the manufacturing cost by the simple circuit design.
The present invention will become more fully understood from the subsequent detailed description and accompanying drawings, which are given by way of illustration only, and thus are not limitative of the present invention, and wherein:
The present invention will be apparent from the following detailed description, which proceeds with reference to the accompanying drawings, wherein the same references relate to the same elements.
The first touch unit 21 includes a touch substrate (not shown) and a first conductive layer 211. The touch substrate can be a substrate of a touch panel, which is made of glass or plastic. The first conductive layer 211 is shown as the solid lines in the figure and includes a plurality of sensing conductive bars. Each of the sensing conductive bars is formed by connecting a plurality of sensing electrodes 6 in series. The sensing electrode 6 of the sensing conductive bar can be rhombic, square, circular, elliptic, polygonal or irregular. In this embodiment, the sensing electrode 6 is, for example but not limited to, rhombic.
The first touch unit 21 further includes a second conductive layer 212, which also includes a plurality of sensing conductive bars. The sensing conductive bars of the second conductive layer 212 and the sensing conductive bars of the first conductive layer 211 are extended in perpendicular to each other. One end of the second conductive layer 212 is electrically connected with the first voltage difference retrieving unit 22. The sensing electrodes of the sensing conductive bars of the second conductive layer 212 can be rhombic, square, circular, elliptic, polygonal or irregular. In this embodiment, the sensing electrode is, for example but not limited to, rhombic.
The first touch unit 21 further includes an insulation layer (not shown), which is disposed between the first conductive layer 211 and the second conductive layer 212 for preventing the electrical connection between the first conductive layer 211 and the second conductive layer 212.
The first voltage difference retrieving unit 22 is electrically connected with one end of the first conductive layer 211, and it includes a voltage-drop device 221, a first retrieving device 222 and a second retrieving device 223. The voltage-drop device 221 can be a capacitor or a resistor. In this embodiment, the voltage-drop device 221 is, for example but not limited to, a resistor. The first retrieving device 222 connects to one end of the voltage-drop device 221, and the connecting node thereof outputs a first voltage signal V1. The second retrieving device 223 connects to the other end of the voltage-drop device 221, and the connecting node thereof outputs a second voltage signal V2. In this embodiment, each of the first retrieving device 222 and the second retrieving device 223 is a voltage follower for example.
The first feedback signal generating unit 23 is electrically connected with the first voltage difference retrieving unit 22. In detailed, the first feedback signal generating unit 23 includes an operation device 231 for receiving the first voltage signal V1 and the second voltage signal V2, and then the first feedback signal generating unit 23 outputs a voltage difference signal V3 according to the voltage difference between the first voltage signal V1 and the second voltage signal V2. In this embodiment, the operation device 231 is a differential amplifier for example. In addition, the first feedback signal generating unit 23 further includes a filter 232, a comparator 233, a subtractor 234, and an amplifier circuit 235. The filter 232 receives the voltage difference signal V3 and outputs a voltage signal V4 to the subtractor 234. The output of the filter 232 is electrically connected with the comparator 233. A reference voltage Vth is inputted to the comparator 233, and the comparator 233 outputs a signal V21 to the control unit 24. The subtractor 234 outputs a voltage signal V6 by subtracting a voltage signal V5 from the voltage signal V4. Herein, the voltage signal V5 is provided by an external circuit or a microprocessor 241 of the control unit 24. Finally, the voltage signal V6 is processed by the amplifier circuit 235 to generate a first feedback signal V7. In this embodiment, the filter 232 is a band-pass filter for example. In addition, it is possible to add or remove the amplifier circuit 235 based on different circuit designs. In the capacitive touch apparatus 2 of this embodiment, the first feedback signal generating unit 23 includes the amplifier circuit 235 for example.
The control unit 24 is electrically connected with the first voltage difference retrieving unit 22 and the first feedback signal generating unit 23. The control unit 24 includes a microprocessor 241 and a waveform modulator 242. The microprocessor 241 receives the first feedback signal V7 and converts the analog first feedback signal V7 into a digital signal, thereby outputting a voltage signal V8. Accordingly, the voltage signal V8 is a square-wave voltage signal. The waveform modulator 242 receives the voltage signal V8 and converts it into a sine-wave power signal V9. Finally, the power signal V9 is outputted to the first voltage difference retrieving unit 22 and the first selection unit 25, so that the first voltage difference retrieving unit 22 and the first selection unit 25 can be powered on and enabled.
The first selection unit 25 is electrically connected with the first touch unit 21 and the first voltage difference retrieving unit 22. In this embodiment, the first selection unit 25 includes at least one multiplexer, at least one resistor, and at least one switch device. As shown in
Moreover, the capacitive touch apparatus 2 of the present embodiment further includes a second voltage difference retrieving unit 26, a second feedback signal generating unit 27, and a second selection unit 28.
The second voltage difference retrieving unit 26 is electrically connected with one end of the first conductive layer 211 opposite to the first voltage difference retrieving unit 22. Similarly, the second voltage difference retrieving unit 26 includes a voltage-drop device 261, a first retrieving device 262 and a second retrieving device 263. The voltage-drop device 261 can be a capacitor or a resistor. In this embodiment, the voltage-drop device 261 is a resistor for example. The first retrieving device 262 connects to one end of the voltage-drop device 261, and the connecting node thereof outputs a first voltage signal V11. The second retrieving device 263 connects to the other end of the voltage-drop device 261, and the connecting node thereof outputs a second voltage signal V12. In this embodiment, each of the first retrieving device 262 and the second retrieving device 263 is a voltage follower for example.
The second feedback signal generating unit 27 is electrically connected with the second voltage difference retrieving unit 26. In detailed, the second feedback signal generating unit 27 includes an operation device 271 for receiving the first voltage signal V11 and the second voltage signal V12, and then the second feedback signal generating unit 27 outputs a voltage difference signal V13 according to the voltage difference between the first voltage signal V11 and the second voltage signal V12. In this embodiment, the operation device 271 is a differential amplifier for example. In addition, the second feedback signal generating unit 27 further includes a filter 272, a comparator 273, a subtractor 274, and an amplifier circuit 275. The filter 272 receives the voltage difference signal V13 and outputs a voltage signal V14 to the subtractor 274. The output of the filter 272 is electrically connected with the comparator 273. A reference voltage Vth is inputted to the comparator 273, and the comparator 273 outputs a signal V22 to the control unit 24. The subtractor 274 outputs a voltage signal V16 by subtracting a voltage signal V15 from the voltage signal V14. Herein, the voltage signal V15 is provided by an external circuit or a microprocessor 241 of the control unit 24. Finally, the voltage signal V16 is processed by the amplifier circuit 275 to generate a second feedback signal V17. In this embodiment, the filter 272 is a band-pass filter for example. In addition, it is possible to add or remove the amplifier circuit 275 based on different circuit designs. In the capacitive touch apparatus 2 of this embodiment, the second feedback signal generating unit 27 includes the amplifier circuit 275 for example.
The second selection unit 28 is electrically connected with the first touch unit 21 and the second voltage difference retrieving unit 26. In this embodiment, the second selection unit 28 includes at least one multiplexer, at least one resistor, and at least one switch device. As shown in
In this embodiment, the second voltage difference retrieving unit 26 is electrically connected with one end of part of the second conductive layer 212, and one end of the other part of the second conductive layer 212 is electrically connected with the first voltage difference retrieving unit 22.
The structure of the capacitive touch apparatus 2 of the present invention is illustrated hereinabove, and the practical application and operation thereof will be described herein below with reference to
The control unit 24 provides a power signal V9 to the first voltage difference retrieving unit 22, the first selection unit 25, the second voltage difference retrieving unit 26, and the second selection unit 28. The microprocessor 241 of the control unit 24 controls the switches of the multiplexers 251 and 281 of the first and second selection units 25 and 28, so as to scan the sensing conductive bars of the first and second conductive layers 211 and 212 back and forth. The first selection unit 25 is electrically connected with the first voltage difference retrieving unit 22, and the second selection unit 28 is electrically connected with the second voltage difference retrieving unit 26. The first retrieving devices 222 and 262 retrieves one end of the voltage-drop devices 221 and 261 to output the first voltage signals V1 and V11 to the operation devices 231 and 271. On the contrast, the second retrieving devices 223 and 263 retrieves the other end of the voltage-drop devices 221 and 261 to output the second voltage signals V2 and V12 to the operation devices 231 and 271. Accordingly, the capacitive touch apparatus 2 can determine whether the finger touches the touch substrate or not.
The following description will take the detection of the first conductive layer 211 as an example. After the operation device 231 calculates with the first voltage signal V1 and the second voltage signal V2, it outputs the voltage difference signal V3. Then, the filter 232 filters the signal to generate the voltage signal V4, which is then transmitted to the comparator 233 and the subtractor 234. Before entering into the comparator 233, the waveform of the voltage signal V4 is a sine-wave voltage signal. The comparator 233 compares the voltage signal V4 with a reference voltage Vth and then outputs a signal V21 to the microprocessor 241. The signal V21 is a square-wave signal. The subtractor 234 can subtract the voltage signal V5 from the voltage signal V4 to obtain the voltage signal V6, which is amplified by the amplifier circuit 235 to obtain the first feedback signal V7. The microprocessor 241 utilizes the rising edge of the signal V21 to trigger a counter to start counting. When counter counts to time T1, the microprocessor 241 starts to read the voltage value of the first feedback signal V7. To be noted, the microprocessor 241 may also utilize the falling edge of the signal V21 to trigger the counter, and, in the case, the counter will count to time T3. After reading the voltage value of the first feedback signal V7, the microprocessor 241 performs the AC/DC conversion. At this moment, the read voltage value is the peak of the first feedback signal V7. When the finger touches the sensing lines, the peak of the first feedback signal V7 is changed (normally it is increased). As shown in
After calculating with the first voltage signal V11 and the second voltage signal V12, the operation device 271 outputs the voltage difference signal V13. Then, the filter 272 filters the signal to generate the voltage signal V14, which is then transmitted to the comparator 273 and the subtractor 274. The comparator 273 compares the voltage signal V14 with the reference voltage Vth and then generates a signal V22, which is a square-wave voltage signal. The subtractor 274 subtracts the voltage signal V15 from the voltage signal V14 to obtain the voltage signal V16, which is amplified by the amplifier circuit 275 to obtain the second feedback signal V17. The microprocessor 241 utilizes the rising edge of the signal V22 to trigger a counter to start counting. When counter counts to time T2, the microprocessor 241 starts to read the voltage value of the second feedback signal V17. To be noted, the microprocessor 241 may also utilize the falling edge of the signal V22 to trigger the counter, and, in the case, the counter will count to time T4. After reading the voltage value of the second feedback signal V17, the microprocessor 241 performs the AC/DC conversion. At this moment, the read voltage value is the peak of the second feedback signal V17. When the finger touches the sensing lines, the peak of the second feedback signal V17 is changed (normally it is increased). As shown in
It is also possible to directly utilize the rising edge of the signal V21 to trigger the counter to start counting with regardless the comparator 273 and the signal V22. In this case, after the counter counts to time T5, the voltage value of the second feedback signal V17 is read. Then, the microprocessor 241 performs the AC/DC conversion. Alternatively, it is also possible to utilize the falling edge of the signal V21 to trigger the counter to start counting. In this case, after the counter counts to time T6, the voltage value of the second feedback signal V17 is read for performing the AC/DC conversion.
After obtaining the variations Vai and Vbi of the voltage differences between two ends of a single sensing conductive bar of the first conductive layer 211 (Vai=Vap−Vax,Vbi=Vbp−Vbx), and switching all sensing conductive bars of the same direction (e.g. the horizontal direction) by the multiplexers 251 and 281, the variations Vai and Vbi is multiplied by the coordinates Xi of the sensing conductive bars respectively so as to obtain the centroid coordinate X, which represents the X-axle coordinate value of the touch position. The centroid coordinate X can be calculated by the following Equations (1), (2), and (3). Herein, the first conductive layer 211 of the first touch unit 21 has 1st to Nth sensing conductive bars, and i is between 1 to N.
If only the data relate to the first conductive layer 211 is available, the coordinate Y, which represent the Y-axle coordinate value of the touch position, can be obtained according to the following Equation (4).
Y=(Vai−Vbi)/(Vai+Vbi) Equation (4).
After obtaining the variations Vci and Vdi of the voltage differences between two ends of a single sensing conductive bar of the second conductive layer 212, and switching all sensing conductive bars of the same direction (e.g. the vertical direction) by the multiplexers 251 and 281, the variations Vci and Vdi is multiplied by the coordinates Yi of the sensing conductive bars respectively so as to obtain the centroid coordinate Y, which represents the Y-axle coordinate value of the touch position. The centroid coordinate Y can be calculated by the following Equations (5), (6), and (7). Herein, the second conductive layer 212 of the first touch unit 21 has 1st to Nth sensing conductive bars, and i is between 1 to N.
If only the data relate to the second conductive layer 212 is available, the coordinate X, which represent the X-axle coordinate value of the touch position, can be obtained according to the following Equation (8).
X=(Vci−Vdi)/(Vci+Vdi) Equation (8).
The various aspects of the first selection unit and the second selection unit of the capacitive touch apparatus will be described with reference to
Referring to
Referring to
Referring to
The various aspects of the first touch unit of the capacitive touch apparatus will be described with reference to
Referring to
Referring to
For the concise purpose, some elements, such as the first and second voltage difference retrieving units, the first and second feedback signal generating units, and the first and second selection units, are omitted in the following figures.
The first touch unit 21 may further connect to a plurality of buttons, bar stick, or arc stick for replacing the sensing conductive bars. As shown in
To be noted, the above aspects of various first touch units are for illustrations only, and the connections or the amount of the connected buttons may different for various aspects of the first touch units.
The various aspects of the capacitive touch apparatus will be described with reference to
Referring to
Referring to
Referring to
Referring to
Referring to
In summary, the capacitive touch apparatus of the present invention is configured with a first selection unit with a multiplexer for switching the connections between the first voltage difference retrieving unit and a plurality of sensing conductive bars of the first touch unit. In addition, the first voltage difference retrieving unit includes a first retrieving device and a second retrieving device for respectively retrieving the voltages of two ends of the voltage-drop device so as to determine the touch position and touch time. Furthermore, the capacitive touch apparatus of the present invention further includes a second touch unit, which is electrically connected with the first touch unit, without increasing complex connections and detecting the touch position. Accordingly, the capacitive touch apparatus of the present invention can improve the sensing speed and reduce the manufacturing cost by the simple circuit design.
Although the present invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternative embodiments, will be apparent to persons skilled in the art. It is, therefore, contemplated that the appended claims will cover all modifications that fall within the true scope of the present invention.
Number | Date | Country | Kind |
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099141663 | Dec 2010 | TW | national |