JP5369219B2 - Touch detection device and touch detection method thereof - Google Patents

Description

  The present invention relates to a touch detection device, and more particularly to a touch detection device and a touch detection method for detecting an AC signal of a human body.

  Conventional touch technologies are roughly classified into resistance type, capacitive type, optical type, and sound wave type according to the detection principle. The resistance type detection method measures a voltage change caused by pressing of the electrode. The capacitive detection method measures a change in capacitance value due to a current generated by touching an electrode with a human body. The optical detection method achieves the purpose of detecting a position with a touch by detecting that a light ray is blocked or absorbed. The sound wave type detection method achieves the object of detecting the position by touch by detecting that the sound wave is blocked or absorbed.

  It is an object of the present invention to provide a touch detection device and a touch detection method thereof that can achieve the object of detecting by touch by detecting a weak AC signal by a human body in an environment where an electronic device is placed. To do.

  The touch detection device according to the present invention includes a touch detection circuit, a phase delay circuit, and a determination circuit. The phase delay circuit is electrically connected to the touch detection circuit. The determination circuit is electrically connected to the touch detection circuit and the phase delay circuit. The touch detection circuit includes at least one conductive unit. The conductive unit generates an AC touch signal when the distance between the charged object and the conductive unit is within a predetermined distance. The phase delay circuit receives an AC touch signal from the touch detection circuit and generates a delay signal by delaying the AC touch signal by a predetermined phase. The determination circuit obtains the waveform superposition time by comparing the signal strength of the AC touch signal and the signal strength of the delay signal with threshold values. The waveform superposition time is a time during which the waveform of the AC touch signal is larger than the threshold and the time when the waveform of the delay signal is larger than the threshold are superimposed. When the waveform superposition time is longer than the predetermined time, the determination circuit determines that the conductive unit of the touch detection circuit is approaching or touched by a human body.

  The touch detection method according to the present invention is applied to a touch detection device. The touch detection device includes at least one conductive unit. The conductive unit generates an AC touch signal when the distance between the charged object and the conductive unit is within a predetermined distance. The touch detection method includes a step of acquiring an AC touch signal output from the conductive unit, a step of generating a delay signal by delaying the AC touch signal by a predetermined phase, a signal strength of the AC touch signal, and a signal strength of the delay signal. Are respectively compared with a threshold value to obtain a waveform superposition time which is a time when the waveform of the AC touch signal is larger than the threshold and a time when the waveform of the delay signal is larger than the threshold, and the waveform superposition time. Determining whether or not is greater than a predetermined time.

  According to the touch detection device and the touch detection method according to the present invention, detection is made by touch by coupling a weak AC signal from a human body in an environment where an electronic device is placed by a conductive unit included in the touch detection device. The purpose of performing can be achieved.

1 is a circuit block diagram of a touch detection device according to the present invention. FIG. FIG. 4 is a signal waveform diagram of the touch detection device according to the present invention. 1 is a circuit block diagram of a touch detection device according to the present invention. FIG. 3 shows a flowchart of a touch detection method according to the present invention.

(Example of touch detection device and touch detection method thereof)
As illustrated in FIG. 1A, the touch detection device 1 includes a touch detection circuit 12, a phase delay circuit 14, and a determination circuit 16. The touch detection circuit 12 includes at least one conductive unit 121 and a current-voltage conversion unit 123 for converting current into voltage. In FIG. 1A, there is only one conductive unit 121, but the quantity is not particularly limited. The determination circuit 16 includes a first comparator 161, a second comparator 163, and a logical operation unit 165.

  The phase delay circuit 14 is electrically connected to the touch detection circuit 12. The determination circuit 16 is electrically connected to the touch detection circuit 12 and the phase delay circuit 14. The current-voltage conversion unit 123 is electrically connected between the conductive unit 121 and the phase delay circuit 14. The first comparator 161 is electrically connected to the current / voltage conversion unit 123. The second comparator 163 is electrically connected to the phase delay circuit 14. The logical operation unit 165 is electrically connected to the first comparator 161 and the second comparator 163.

  Please refer to FIG. 1A and FIG. 1B. The conductive unit 121 of the touch detection circuit 12 is for generating an AC touch signal. When the distance between the charged object (for example, human body) and the conductive unit 121 is within a predetermined distance (for example, 3 mm), the conductive unit 121 generates an AC touch signal. In the present embodiment, the conductive unit 121 is for generating an AC touch signal in a current format. In other words, when the conductive unit 121 approaches or touches a human body (for example, a human hand), a weak AC signal from the human body is coupled to the conductive unit 121 (for example, coupled to an electronic device). To generate a current. The current is an AC touch signal. That is, since the conductive unit 121 can detect the AC signal of the human body by the coupling method, even if the human body or other conductor does not touch the conductive unit 121, the distance between the human body or other conductor and the conductive unit 121. Is within a predetermined distance, the conductive unit 121 generates a sufficient detection current and transmits the detection current to the current-voltage conversion unit 123. Hereinafter, a case where a human body (or another conductor) touches the conductive unit 121 will be described as an example. The approach of the human body (or other conductor) to the conductive unit 121 to a predetermined distance is almost equivalent to the human body touching the conductive unit 121, but the difference is in the magnitude of the detected current.

  The current-voltage conversion unit 123 converts the current signal from the conductive unit 121 into a voltage-type AC touch signal TC, and transmits the voltage-type AC touch signal TC to the phase delay circuit 14 and the first comparator 161. In FIG. 1B, a waveform W1 is an AC touch signal TC when the human body touches the conductive unit 121, and a waveform W2 is an AC touch signal TC when the human body does not touch the conductive unit 121. In principle, the AC touch signal TC when the human body does not touch the conductive unit 121 is noise due to the environment. Therefore, whether or not the human body touches the conductive unit 121 is related to whether or not the AC touch signal TC changes significantly. For example, there is a significant difference between the waveform W1 and the waveform W2.

  The phase delay circuit 14 receives the AC touch signal TC from the touch detection circuit 12, and generates the delay signal TC1 by delaying the AC touch signal TC by a predetermined phase. In FIG. 1B, a waveform W3 is a delay signal TC1 when the human body touches the conductive unit 121, and a waveform W4 is a delay signal TC1 when the human body does not touch the conductive unit 121.

  The determination circuit 16 acquires the waveform superposition time by comparing the signal strength of the AC touch signal TC and the signal strength of the delay signal TC1 with the threshold value TH. The threshold value TH may be generated by a voltage dividing circuit. The threshold value TH can be adjusted. By adjusting the threshold TH, the determination sensitivity of the determination circuit 16 that determines whether or not the human body touches the conductive unit 121 can be adjusted. The waveform superposition time is a time during which the waveform of the AC touch signal TC is larger than the threshold TH and the time when the waveform of the delay signal TC1 is larger than the threshold TH. When the waveform superposition time is longer than the predetermined time, the determination circuit 16 determines that the conductive unit 121 of the touch detection circuit 12 is touched by the human body. On the other hand, when the waveform superposition time is shorter than the predetermined time, the determination circuit 16 determines that the conductive unit 121 of the touch detection circuit 12 is not touched by the human body. The output signal TR output from the logical operation unit 165 represents a waveform superposition time to be used in a subsequent circuit so as to perform an operation related to the touch function. Hereinafter, a method for acquiring the waveform superposition time will be described.

  When the human body touches the conductive unit 121, the first comparator 161 generates the comparison signal W5 by comparing the AC touch signal TC (waveform W1) from the current-voltage conversion unit 123 with the threshold value TH. When the signal intensity of the AC touch signal TC (waveform W1) is greater than the threshold value TH, the comparison signal W5 is at the first signal level. On the other hand, when the signal intensity of the AC touch signal TC (waveform W1) is smaller than the threshold value TH, the comparison signal W5 is at the second signal level. The second comparator 163 generates the comparison signal W6 by comparing the delay signal TC1 (waveform W3) with the threshold value TH. When the signal strength of the delay signal TC1 (waveform W3) is larger than the threshold value TH, the comparison signal W6 is at the first signal level. On the other hand, when the signal strength of the delay signal TC1 (waveform W3) is smaller than the threshold value TH, the comparison signal W6 is at the second signal level. The logical operation unit 165 obtains the waveform superposition time T1 by performing a logical operation on the comparison signal W5 and the comparison signal W6. Like the waveform W9 shown in FIG. 1B, the waveform superposition time T1 is a time during which both the comparison signal W5 and the comparison signal W6 are at the first signal level (high voltage level).

  On the other hand, when the human body does not touch the conductive unit 121, the first comparator 161 generates the comparison signal W7 by comparing the AC touch signal TC (waveform W2) from the current-voltage conversion unit 123 with the threshold value TH. When the signal strength of the AC touch signal TC (waveform W2) is greater than the threshold value TH, the comparison signal W7 is at the first signal level. On the other hand, when the signal intensity of the AC touch signal TC (waveform W2) is smaller than the threshold value TH, the comparison signal W7 is at the second signal level. The second comparator 163 generates the comparison signal W8 by comparing the delay signal TC1 (waveform W4) with the threshold value TH. When the signal strength of the delayed signal TC1 (waveform W4) is greater than the threshold value TH, the comparison signal W8 is at the first signal level. On the other hand, when the signal strength of the delay signal TC1 (waveform W4) is smaller than the threshold value TH, the comparison signal W8 is at the second signal level. The logical operation unit 165 obtains the waveform superposition time T2 by performing a logical operation on the comparison signal W7 and the comparison signal W8. Like the waveform W10 shown in FIG. 1B, the waveform superposition time T2 is a time when both the comparison signal W7 and the comparison signal W8 are at the first signal level. As shown in FIG. 1B, the greater the difference between the waveform superposition time T1 and the waveform superposition time T2, the easier it is to determine whether or not the conductive unit 121 is approached or touched by a human body. The predetermined time for determining whether or not the conductive unit 121 is close to or touches the human body may be set to be shorter than the waveform superposition time T1 and longer than the waveform superposition time T2.

  In FIG. 1B, the determination is made based on the positive waveform of the half cycle of the AC touch signal TC and the delay signal TC1, but the determination is made based on the negative waveform of the AC cycle signal TC and the delay signal TC1. Also good. In this case, the threshold value may be a negative number. Regardless of the positive waveform or the negative waveform of the half cycle, the signal strength of the AC touch signal TC and the signal strength of the delay signal TC1 are compared with the threshold value TH.

  This will be described with reference to FIGS. 1A and 2. The touch detection device 2 includes a touch detection circuit 22, a phase delay circuit 24, a determination circuit 26, and a signal amplification circuit 28. The touch detection circuit 22 includes at least one conductive unit 221 and a current-voltage conversion unit 223 for converting a current into a voltage. The determination circuit 26 includes a first comparator 261, a second comparator 263, and a logical operation unit 265. The logical operation unit 265 includes an AND logic unit 267 and a counter 269.

  The touch detection device 2 shown in FIG. 2 and the touch detection device 1 shown in FIG. 1A are almost the same, except that a signal amplification circuit 28 is added in FIG. 2 and the logical operation unit 265 is different from the AND logic unit 267. It consists of a counter 269. The signal amplifier circuit 28 is electrically connected to the current-voltage conversion unit 223, the phase delay circuit 24, and the first comparator 261. The signal amplifying circuit 28 amplifies the voltage-type AC touch signal TC output from the current-voltage conversion unit 223, and the amplified voltage-type AC touch signal TC ′ is compared with the phase delay circuit 24 for the first comparison. It is for conveying to the container 261.

  This will be described with reference to FIGS. 1B and 2. The AND logic unit 267 is electrically connected to the first comparator 261 and the second comparator 263. The AND logic unit 267 is for generating a waveform superimposed signal by performing an AND operation (Logical AND) on the comparison signal CA and the comparison signal CB. The waveform superimposed signals are the waveforms W9 and W10 shown in FIG. 1B. The counter 269 is electrically connected to the AND logic unit 267, and the duration when the waveform superposition signals (waveforms W9 and W10) are at the first signal level (for example, the high voltage level shown in FIG. 1B). To calculate the waveform superposition time (T1, T2). For example, the counter 269 counts the output enable time of the AND logic unit 267. “Enable” means that the logic is at a high level. The counter 269 may count the waveform superimposed signals (waveforms W9 and W10) output from the AND logic unit 267 after receiving the high level of the comparison signal CA. On the other hand, when the AND logic unit 267 is not enabled (low level), the counter 269 does not count.

  This will be described with reference to FIGS. 1A, 1B, and 3. FIG. The touch detection method illustrated in FIG. 3 is applied to the touch detection device 1. The touch detection device 1 includes at least one conductive unit. When the distance between the charged object (eg, human body) and the conductive unit is within a predetermined distance, the conductive unit generates an AC touch signal. The touch detection method includes the following steps. First, in step S310, an AC touch signal output from the conductive unit 121 is acquired. Further, in step S310, after acquiring the AC touch signal output from the conductive unit 121, the AC touch signal may be amplified by, for example, the signal amplification circuit 28 illustrated in FIG.

  In step S320, delayed signals (waveforms W3 and W4) are generated by delaying the AC touch signals (waveforms W1 and W2) by a predetermined phase. In step S330, the waveform superposition time (T1, T2) is obtained by comparing the signal strength of the AC touch signal and the signal strength of the delay signal with the threshold value TH. The waveform superposition time is a time during which the waveform of the AC touch signal is larger than the threshold value TH and the time when the waveform of the delay signal is larger than the threshold value TH are superimposed. In step S340, it is determined whether the waveform superposition time is longer than a predetermined time. When the waveform superposition time is longer than the predetermined time, it is determined that the conductive unit has approached or been touched by the charged object. On the other hand, when the waveform superposition time is shorter than the predetermined time, it is determined that the conductive unit is not approaching or touching the charged object. After step S340 is completed, step S310 is executed again.

(Effect of Example)
According to the touch detection device and the touch detection method according to the present invention, the conductive unit is coupled by coupling a weak AC signal from the human body in an environment where the electronic device is placed by the conductive unit included in the touch detection device. It is determined whether or not the human body is approached or touched. Further, the determination sensitivity can be improved by delaying the phase of the AC touch signal. Further, since the AC touch signal is an AC signal, it can be determined by performing a logical operation regardless of the positive waveform or the negative waveform of the half cycle of the AC touch signal. In addition, it is useful for logic operation to install a signal amplification circuit between the touch detection circuit and the phase delay circuit.

  What has been described above is merely a preferred example of the present invention and does not limit the embodiments of the present invention.

1, 2 Touch detection device 12, 22 Touch detection circuit 14, 24 Phase delay circuit 16, 26 Judgment circuit 121, 221 Conductive unit 123, 223 Current-voltage conversion unit 161, 261 First comparator 163, 263 Second comparison 165, 265 Logical operation unit 28 Signal amplification circuit 267 AND logic unit 269 Counter TH threshold TC AC touch signal TC1 Delay signal CA, CB Comparison signal TR Output signal

Claims (6)

A touch detection circuit comprising at least one conductive unit for generating an AC touch signal when the distance to the charged object is within a predetermined distance;
A phase delay circuit that is electrically connected to the touch detection circuit, receives the AC touch signal from the touch detection circuit, and generates a delay signal by delaying the AC touch signal by a predetermined phase;
The waveform of the AC touch signal is electrically connected to the touch detection circuit and the phase delay circuit, and the waveform of the AC touch signal is compared with the threshold value by comparing the signal intensity of the AC touch signal and the signal intensity of the delay signal with a threshold value A determination circuit that obtains a waveform superposition time that is a time over which a waveform of the delayed signal is superposed over a time greater than the threshold;
Including
When the waveform superposition time is greater than a predetermined time, the determination circuit determines that the conductive unit of the touch detection circuit has approached or touched a charged object, and when the waveform superposition time is smaller than the predetermined time, The touch detection device, wherein the determination circuit determines that the conductive unit of the touch detection circuit is not approaching or touching a charged object.   The touch detection circuit includes a current-voltage conversion unit that is electrically connected between the conductive unit and the phase delay circuit and converts a current signal from the conductive unit into the AC touch signal in a voltage format. The touch detection device according to claim 1, further comprising: The determination circuit includes:
A first comparison signal is generated by comparing the threshold value with the AC touch signal from the current / voltage conversion unit, electrically connected to the current / voltage conversion unit, and the signal strength of the AC touch signal is When the threshold value is greater than the threshold, the first comparison signal is at a first signal level, and when the signal strength of the AC touch signal is less than the threshold value, the first comparison signal is at a second signal level. A first comparator configured to be;
The second comparison signal is electrically connected to the phase delay circuit, and the second comparison signal is generated by comparing the delay signal with the threshold value. When the signal strength of the delay signal is larger than the threshold value, the second The second comparison signal is at the second signal level when the comparison signal is at the first signal level and the signal strength of the delayed signal is less than the threshold. A comparator;
The first comparator and the second comparator are electrically connected, and the first comparison signal and the second comparison signal are logically calculated by performing a logical operation on the first comparison signal and the second comparison signal. A logical operation unit for obtaining the waveform superposition time, which is a time when both of the two comparison signals are at the first signal level;
The touch detection device according to claim 2, further comprising: A signal amplifier circuit;
The signal amplification circuit is electrically connected to the current-voltage conversion unit, the phase delay circuit, and the first comparator, and amplifies the AC touch signal in a voltage format output from the current-voltage conversion unit. The touch detection apparatus according to claim 3, wherein the AC touch signal in an amplified voltage format is transmitted to the phase delay circuit and the first comparator. The logical operation unit is:
An AND for electrically connecting to the first comparator and the second comparator, and for obtaining a waveform superimposed signal by performing an AND operation on the first comparison signal and the second comparison signal. A logical unit;
A counter electrically connected to the AND logic unit to obtain the waveform superposition time by calculating a duration when the waveform superposition signal is at the first signal level;
The touch detection device according to claim 3, further comprising: A touch detection method applied to a touch detection device including at least one conductive unit for generating an AC touch signal when a distance from a charged object is within a predetermined distance,
Obtaining an AC touch signal output by the conductive unit;
Generating a delayed signal by delaying the alternating touch signal by a predetermined phase;
By comparing the signal strength of the AC touch signal and the signal strength of the delayed signal with a threshold value, respectively, the time when the waveform of the AC touch signal is larger than the threshold value and the time when the waveform of the delayed signal is larger than the threshold value. Obtaining a waveform superposition time which is a time at which
Determining whether the waveform superposition time is greater than a predetermined time;
The touch detection method characterized by including.

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