TWI484392B - Sensing device and method for touch panel - Google Patents

Description

Touch panel reading method and device

The present invention relates to a method and apparatus for interpreting, and more particularly to a method and apparatus for interpreting a touch panel.

At present, capacitive touch sensing technology applied to touch panels mostly uses analog/digital (A/D) conversion technology to analyze changes in capacitance potential. For example, when a finger touches a circuit board or a glass panel, the charge absorbed by the finger is very limited, and the charge that is not absorbed by the finger is divided into two parts: one part radiates into space and the other part is directly coupled. To the integrator and the amplification device.

The signal potential coupled to the integrator and the amplifying device will form a touch potential value of the touch point, and the touch potential value is compared with the original potential value when the touch point is not touched, and the touch is known. The ratio of the potential value to the original potential value is about 80% to 90%. That is to say, the difference between the touch potential value and the original potential value accounts for only 10% to 20% of the original potential value.

It can be seen that after A/D conversion, the effective data range is only 10% to 20% of the number of bits of the A/D conversion circuit. Therefore, if the characteristics of the touch capacitor board are not good, the sensitivity of the sensing is likely to be deteriorated. However, if the resolution is to be improved, the number of bits of the A/D conversion circuit must be increased or an additional circuit must be added. However, this will lead to an increase in the design cost of the circuit.

Secondly, if the size of the panel is large, the amount of touch points will also increase. In the case of analog/digital conversion technology, a longer scan time will seriously affect the smoothness of use.

Finally, for large-size panels, the energy obtained at the far-end capacitor is re-transmitted to each equivalent capacitor because the impedance of the capacitor distributed at the far-end is large. Compared to the near-end capacitor Low, so the touch sensitivity of large-sized panels is greatly affected.

In order to improve the above problem, the US 2007/0247172 A1 case proposes a touch device, but it has the following disadvantages: (1) the button is charged to ground (GND) and then transferred from the button charge to another capacitor for potential comparison, Carrying out charge transfer; (2) not mentioning how the counting method is performed; (3) charging only a single button to the ground; and (4) not integrating the potential after amplification, and then comparing, so the required charging speed is higher. slow.

Therefore, it is necessary to conceive a method and apparatus for interpretation of a touch panel that does not require the use of A/D conversion technology.

According to the above concept, the present invention provides a method and apparatus for reading a touch panel, wherein any touch point on the touch panel is electrically connected to a touch capacitor, and the method includes the following steps: The charge energy is integrated and amplified to obtain a reference potential value for a total length of time, wherein the total length of time is a sum of a reference time length and an extra length of time; and within the total length of time, the reference After the length of time has elapsed, the extra time length is counted by a system clock to determine the touch point.

According to the above concept, the present invention further provides a reading device for a touch panel, wherein any touch point on the touch panel is electrically connected to a touch capacitor, and the reading device comprises: an integrating amplifier having a first input a second input end and an output end, the first input end is electrically coupled to the output end of the touch capacitor, the second input end is electrically coupled to the ground, wherein the integrating amplifier touches the touch The charge energy of the capacitor is integrated and amplified, thereby obtaining a reference potential value for a total length of time, and the total length of time is a reference time length And a sum of an additional length of time; a comparator having a non-inverting input, an inverting input, and an output, the non-inverting input being electrically coupled to the output of the integrating amplifier, the inverting The input terminal receives the reference potential value; and a counter electrically coupled to the output of the comparator, wherein the counter is controlled by the comparator, and within the total length of time, after the reference time length elapses The extra time length is counted by a system clock to determine the touch point.

In this case, the reference potential of the comparator is used to determine whether the system should start to start high-speed counting, because all the charging capacitance levels of the touch capacitor are based on the reference potential of the comparator, so the potential formed by each touch capacitor is also the same. The sensitivity of all touch capacitors on the touch panel is consistent. In addition, because the system uses high-speed counting to count, the resolution can be greatly improved.

This case can be further understood by the following diagrams and detailed explanations:

The main idea of this case is not to use the analog/digital (A/D) conversion technology, but only by integrating the touch capacitors of the touch panel, and then using the high-speed clock to count the time spent on the integration. To determine if the touch point on the touch panel is touched.

Please refer to FIG. 1 , which is a circuit diagram of a preferred embodiment of the interpretation device of the touch panel of the present invention, wherein the interpretation device 1 mainly includes a pulse wave generator 10 (in this embodiment, an oscillator is used). Representative, a switch group 11, an integrating amplifier 12, a comparator 13, a counter 14, and a memory 15.

Any touch point on the touch panel not shown in the figure is electrically connected to a touch capacitor, although only a single touch capacitor 16 is represented in FIG. 1 as a representative, but the person skilled in the art is familiar with the present technology. It is known that in the case of using an additional multiplexer, the interpretation device 1 of Fig. 1 can be responsible for the interpretation of the respective touch points on the entire touch panel.

The interpretation device of the touch panel proposed in the present invention is configured as follows: the integrating amplifier 12 has a first input terminal, a second input terminal and an output terminal, and the first input terminal is electrically coupled to the output of the touch capacitor 16 The second input is electrically coupled to ground.

The comparator 13 has a non-inverting input terminal, an inverting input terminal and an output terminal. The non-inverting input terminal is electrically connected to the output terminal of the integrating amplifier 12, and the inverting input terminal receives a reference potential value Vref.

The counter 14 is electrically coupled to the output of the comparator 13, wherein the counter 14 is controlled by the comparator 13.

In this embodiment, the integrating amplifier 12 is composed of an integrating capacitor 121 and an amplifier 122. The amplifier 122 has a first input terminal, a second input terminal and an output terminal. The first input terminal is electrically The second input is electrically coupled to the ground, and the output is electrically coupled to the output of the integrating capacitor 121.

The pulse generator 10 is electrically coupled to the input end of the touch capacitor 16 for generating a continuous pulse wave and inputting the pulse wave into the touch capacitor, wherein each pulse wave in the continuous pulse wave has a rising edge and a Falling edge.

The switch group 11 has a first end, a second end and a third end. The switch group 11 is electrically coupled between the touch capacitor 16 and the integrating amplifier 12. The first end is electrically coupled to the touch capacitor. The output end of the second end is electrically floated to the first input end of the integrating amplifier 12, and the third end is electrically floating to ground.

In this embodiment, the switch group is composed of a first switch S1 and a second switch S2. The first switch S1 has a first end and a second end. The first end is electrically coupled to the output end of the touch capacitor 16. The second end is electrically floating to ground. The second switch S2 has a first end and a second end. The first end is electrically coupled to the output end of the touch capacitor 16 , and the second end is electrically floated to the first input of the integrating amplifier 12 . end.

The memory 15 is electrically coupled to the counter 14 for storing the counter value of the counter 14.

In order to complete the interpretation method of this case, the interpretation device 1 can be divided into the following two modes during work:

(1) Initial mode

The pulse generator 10 inputs a continuous pulse wave to the touch capacitor 16, and each of the continuous pulse waves has a rising edge and a falling edge.

The switch group 11 is composed of two switches S1 and S2. By opening the switch S1 and turning on the switch S2, only when the rising edge of each pulse wave in the continuous pulse wave passes through the capacitor 16 is touched. The charge energy of the touch capacitor 16 is integrated and amplified by the integrating amplifier 12, and by turning on the switch S1 and turning off the switch S2, the falling edge of each pulse wave in the continuous pulse wave can pass through the touch capacitor. During the period of 16, the charge energy of the touch capacitor 16 is discharged to the ground. By this resetting process, the charge energy equal to the reference potential value Vref can be obtained in the integrating capacitor 121 for a reference time length.

On the other hand, when the integral capacitor 121 is initially charged, the counter 14 starts counting with a reference clock, and when the integral capacitor 121 is integrated into the charge energy equal to the reference potential value Vref, the comparator 13 outputs a low value. The level signal causes the counter 14 to stop counting, at which time the memory 15 will record the reference time length.

Thereafter, the switches S1 and S2 are simultaneously turned on, and the potentials of the integrating capacitor 121 and the touch capacitor 16 are simultaneously reset to zero.

(2) Scan mode

If it is desired to determine whether the touch panel is touched, the scan mode is performed, and the continuous pulse wave having the rising edge and the falling edge is also input to the touch capacitor 16 by the pulse generator 10, and also by the switch group 11 Acting to reach only in that During the rising edge of each pulse wave in the continuous pulse wave, the charge energy of the touch capacitor 16 is integrated and amplified by the integrating amplifier 12 during the contact of the capacitor 16, and only the pulse wave in the continuous pulse wave The falling edge discharges the charge energy of the touch capacitor 16 to the ground during the contact of the capacitor 16. Further, a charge energy equal to the reference potential value Vref is obtained again in the integrating capacitor 121 for another length of time.

Since the touch point electrically connected to the touch capacitor 16 is touched, the capacitance value becomes large, and therefore, only during the rising edge of each pulse wave in the continuous pulse wave passes through the contact capacitor 16, When the charge energy of the touch capacitor 16 is integrated and amplified by the integrating amplifier 12, the length of time required to obtain the charge energy equal to the reference potential value Vref in the integrating capacitor 121 is surely increased; The length is defined as a sum time length, wherein the sum time length is the sum of the aforementioned reference time length and an extra time length.

The difference from the initial mode is that in the scan mode, the counter 14 is within the total length of the time period, and after the lapse of the reference time length, the system clock is counted for the extra time length due to the system clock. With respect to the aforementioned reference clock, which is a very high frequency clock, the interpretation device can use a higher resolution than the prior art, and it is judged that the touch point has indeed been touched.

Please refer to FIG. 2 , which is a comparison diagram of the potential timing of the charge energy stored in the integral capacitor in the initial mode and the scan mode in FIG. 1 . As can be seen from FIG. 2, in the initial mode, the counter 14 starts counting with the reference clock FL, and until the integral capacitor 121 is integrated into the charge energy equal to the reference potential value Vref, the reference time length T is required. -No Touch.

In the scan mode, the total length of time T-Touch that is required to obtain the charge energy equal to the reference potential value Vref in the integrating capacitor 121 must be greater than the reference time length T-No Touch; that is, the The total length of time is the reference time length T-No Touch and the extra time length TC The sum of the counters 14 is counted by the system clock FH for the extra length of time T-C, whereby the touch point is interpreted accordingly.

In summary, in this case, the external integration potential is compared with the self-set reference potential. If the external integration potential reaches the reference potential, the charging time will be recorded, or the counting and stopping counting time will be started at the high-speed frequency, which not only saves The system design cost and energy consumption can improve the resolution of the system to distinguish the touch buttons. Compared with the prior art adopting A/D conversion technology, this case has the following advantages: (1) The counting method in this case is not A/D conversion, so the power consumption is low; (2) Because the system counting level is the comparator reference Level, so all touch capacitors will get the same potential field for detection; (3) This case can be applied to large-size panel and multi-button detection; (4) when the case is applied to the touch panel, due to the comparator The level can be flexibly set, so the design of the capacitor type is more flexible; and (5) the structure is simple, the electric field is uniform, and the resolution is high. On the other hand, compared with the touch device of the aforementioned case of US 2007/0247172 A1, the present invention has the following advantages: (1) the case does not need to perform charge transfer, but directly performs charge integral charging; (2) the case uses high-speed counting mode. (3) The applicable panel of the case is array type, which can be applied to large panel touch detection and multi-key detection; and (4) the case must be integrated and amplified by the integrator, and then the potential is compared. Charging speed is faster.

This case has been modified by people who are familiar with the art, but it is not intended to be protected by the scope of the patent application.

1‧‧‧Interpretation device

10‧‧‧Oscillator

11‧‧‧ switch group

12‧‧‧Integral amplifier

121‧‧‧Integral Capacitance

122‧‧‧Amplifier

13‧‧‧ comparator

14‧‧‧ counter

15‧‧‧ memory

FH‧‧‧ system clock

FL‧‧‧ benchmark clock

T-Touch‧‧‧ total length of time

T-No Touch‧‧‧ benchmark time length

T-C‧‧‧ extra length of time

Vref‧‧‧ reference potential value

1 is a circuit diagram of a preferred embodiment of the interpretation device of the touch panel proposed in the present invention; and FIG. 2 is a comparison diagram of the potential timing of the charge energy stored in the integration capacitor in the initial mode and the scan mode in FIG. .

1‧‧‧Interpretation device

10‧‧‧Oscillator

11‧‧‧ switch group

12‧‧‧Integral amplifier

121‧‧‧Integral Capacitance

122‧‧‧Amplifier

13‧‧‧ comparator

14‧‧‧ counter

15‧‧‧ memory

FL‧‧‧ benchmark clock

Vref‧‧‧ reference potential value

Claims (6)

The invention relates to a reading device for a touch panel, wherein any touch point on the touch panel is electrically connected to a touch capacitor, and the reading device comprises: an integrating amplifier having a first input end and a second input end; And an output end, the first input end is electrically coupled to the output end of the touch capacitor, the second input end is electrically coupled to the ground, wherein the integrating amplifier performs the charge energy of the touch capacitor Integrating the amplification to obtain a reference potential value for a total length of time, and the summed time length is a sum of a reference time length and an extra time length; a comparator having a non-inverting input and an inverting input And an output terminal, the non-inverting input terminal is electrically connected to the output end of the integrating amplifier, the inverting input terminal receives the reference potential value; and a counter electrically coupled to the output end of the comparator Wherein the counter is controlled by the comparator, and within the total length of time, after the length of the reference time elapses, the additional time length is counted by a system clock, according to which Read the touch point. The reading device of claim 1, wherein the integrating amplifier comprises: an integrating capacitor having an input end and an output end; and an amplifier having a first input end, a second input end, and an output end The first input terminal is electrically coupled to the input terminal of the integrating capacitor, the second input terminal is electrically coupled to the ground, and the output terminal is electrically coupled to the output terminal of the integrating capacitor. The reading device of claim 1, further comprising: a pulse generator electrically coupled to the input end of the touch capacitor to generate a continuous pulse wave and input the touch pulse into the touch capacitor, wherein the continuous pulse Each pulse in the wave has a rising edge and a falling edge; and a switch group having a first end, a second end, and a third end, the switch set electrically coupled between the touch capacitor and the integrating amplifier, the first end being electrically coupled to the touch An output end of the capacitive capacitor, the second end is electrically floating to the first input end of the integrating amplifier, and the third end is electrically floating to the ground, wherein the switch group can be switched, and only the The rising edge of each pulse wave in the continuous pulse wave passes through the touch capacitance for integral amplification. The interpretation device of claim 3, wherein the pulse wave generator is an oscillator. The apparatus of claim 3, wherein the switch group further comprises: a first switch having a first end and a second end, the first end being electrically coupled to the output end of the touch capacitor The second end is electrically floated to the ground; and the second switch has a first end and a second end, the first end is electrically coupled to the output end of the touch capacitor, the second The terminal is electrically floating to the first input of the integrating amplifier. The reading device of claim 1, further comprising: a memory electrically coupled to the counter to store the counter value of the counter.