JP7161449B2 - Touch sensors, controllers, and computer programs - Google Patents

Description

The present invention relates to touch sensors. The present invention also relates to a control device that can be mounted on the touch sensor and a computer program that causes the control device to perform a predetermined operation.

Patent Literature 1 discloses a capacitive touch sensor. In the touch sensor, when a user's finger or the like approaches an object positioned within the electric field generated by the electrodes, a pseudo capacitor is formed and the capacitance of the electrodes themselves increases. By detecting this increase in capacity, it is determined whether or not the user has performed an operation on the object.

JP 2015-210811 A

SUMMARY OF THE INVENTION An object of the present invention is to provide a touch sensor capable of accurately determining an operation on an object even in a noisy environment while suppressing an increase in power consumption.

One aspect for achieving the above object is a touch sensor,
an electrode;
a capacitance detection unit having a charging/discharging circuit for detecting the capacitance between the electrode and the object;
a control unit that controls the operation of the charging/discharging circuit;
A first detected capacitance, which is the capacitance detected by operating the charge/discharge circuit at a first frequency, and a first detected capacitance detected by operating the charge/discharge circuit at a second frequency different from the first frequency. A storage unit that stores reference information indicating a correlation with the second detection capacitance that is the capacitance that is detected;
and
The control unit
obtaining the first sensed capacitance;
Acquiring a first reference capacitance corresponding to a reference capacitance for determining whether the object is operated or not;
Based on the amount of change of the first detection capacitance from the first reference capacitance, determining whether or not the object is operated,
When it is determined that there is the operation, the second detection capacitance is obtained,
Comparing the detection information indicating the correlation between the first detection capacitance and the second detection capacitance with the reference information,
The presence or absence of the operation is verified based on the result of the comparison.

Sensing the capacitance between the electrode and the object using two frequencies can be performed to verify the determination that the object has been manipulated. In other words, this is done to prevent erroneous operation detection due to environmental noise. Environmental noise can also change the capacitance between the electrode and the object. Therefore, if it is not possible to distinguish between an increase in capacitance due to manipulation and an increase in capacitance due to environmental noise by monitoring only the first sensed capacitance detected by the operation of the charging/discharging circuit at the first frequency. There is

The above configuration utilizes detection information that indicates the correlation between the first detection capacitance and the second detection capacitance. When the electrode is fully charged, the correlation value between the first reference capacitance and the second reference capacitance when the object is not operated is the first reference capacitance when the object is operated. It substantially matches the correlation value between the detected capacitance and the second detected capacitance. On the other hand, if the object has moisture or if there is environmental noise with frequency characteristics, the first detection capacitance and the second detection capacitance will differ and the correlation value will change. Reference information is different. Therefore, by comparing the detection information with the reference information, it is possible to distinguish between changes in capacitance due to manipulation of the object and changes in capacitance due to environmental noise.

In order to accurately detect the operation on the object, both the first detection capacitance and the second detection capacitance are always detected, and the first reference capacitance and the second reference capacitance are updated. preferred to continue. However, such a configuration suffers from increased power consumption. According to the configuration of the present embodiment, verification based on the operation of the charging/discharging circuit at the second frequency is performed only when it is determined that the object has been operated based on the operation of the charging/discharging circuit at the first frequency. done. Since the frequency of driving the charge/discharge circuit at the second frequency can be reduced, an increase in power consumption of the touch sensor can be suppressed. Therefore, it is possible to accurately determine whether an object has been operated, even in a noisy environment, while suppressing an increase in power consumption.

One aspect for achieving the above object is a control device,
a control unit for controlling the operation of a charge/discharge circuit included in a capacitance detection unit that detects the capacitance between an electrode and an object;
A first detected capacitance, which is the capacitance detected by operating the charge/discharge circuit at a first frequency, and a first detected capacitance detected by operating the charge/discharge circuit at a second frequency different from the first frequency. A storage unit that stores reference information indicating a correlation with the second detection capacitance that is the capacitance that is detected;
and
The control unit
obtaining the first sensed capacitance;
Acquiring a first reference capacitance corresponding to a reference capacitance for determining whether the object is operated or not;
Based on the amount of change of the first detection capacitance from the first reference capacitance, determining whether or not the object is operated,
When it is determined that there is the operation, the second detection capacitance is obtained,
Comparing the detection information indicating the correlation between the first detection capacitance and the second detection capacitance with the reference information,
The presence or absence of the operation is verified based on the result of the comparison.

One aspect for achieving the above object is to operate a charging/discharging circuit included in a capacitance that detects the capacitance between an electrode and an object at a first frequency. and a second detection capacitance that is the capacitance detected by operating the charging/discharging circuit at a second frequency different from the first frequency. A computer program that causes a control device that cooperates with a storage device that stores reference information indicating a correlation with capacitance to control,
By executing the computer program, the control device
detecting the first detection capacitance;
acquire a first reference capacitance corresponding to a reference capacitance for determining whether or not the object is operated;
Based on the amount of change in the first detection capacitance from the first reference capacitance, determining whether or not the object is operated,
When it is determined that there is the operation, acquire the second detection capacitance,
Compare the detection information indicating the correlation between the first detection capacitance and the second detection capacitance with the reference information,
The presence or absence of the operation is verified based on the result of the comparison.

One aspect for achieving the above object is a touch sensor,
an electrode;
a capacitance detection unit having a charging/discharging circuit for detecting the capacitance between the electrode and the object;
a control unit that controls the operation of the charging/discharging circuit;
and
The control unit
Acquiring a first detected capacitance, which is the capacitance detected by operating the charge/discharge circuit at the first frequency,
Acquiring a first reference capacitance corresponding to a reference capacitance for determining whether the object is operated or not;
Based on the amount of change of the first detection capacitance from the first reference capacitance, determining whether or not the object is operated,
When it is determined that there is the operation, obtaining a second detection capacitance that is the capacitance detected by operating the charge and discharge circuit at the second frequency,
generating a second reference capacitance based on reference information indicating a correlation between the first detection capacitance and the second detection capacitance;
The presence or absence of the operation is verified based on the second detection capacitance and the second reference capacitance.

As described above, when the electrode is fully charged, the correlation value between the first reference capacitance and the second reference capacitance when no operation is performed on the object is substantially matches the correlation value between the first detection capacitance and the second detection capacitance when Therefore, based on the reference information corresponding to the correlation value, the second reference capacitance required for verifying that the object has been manipulated can be generated from the second detection capacitance. As a result, when acquiring the second detection capacitance only when it is determined that there is an operation on the object based on the difference between the first detection capacitance and the first reference capacitance, the second reference capacitance is acquired. It can solve the problem that there is no capacitance. Therefore, it is possible to accurately determine the operation on the object even in a noisy environment while suppressing an increase in power consumption by reducing the frequency of driving the charging/discharging circuit at the second frequency.

One aspect for achieving the above object is a control device that controls the operation of a charge/discharge circuit included in a capacitance detection unit that detects the capacitance between an electrode and an object,
Acquiring a first detected capacitance, which is the capacitance detected by operating the charge/discharge circuit at the first frequency,
Acquiring a first reference capacitance corresponding to a reference capacitance for determining whether the object is operated or not;
Based on the amount of change of the first detection capacitance from the first reference capacitance, determining whether or not the object is operated,
When it is determined that there is the operation, obtaining a second detection capacitance that is the capacitance detected by operating the charge and discharge circuit at the second frequency,
generating a second reference capacitance based on reference information indicating a correlation between the first detection capacitance and the second detection capacitance;
The presence or absence of the operation is verified based on the second detection capacitance and the second reference capacitance.

One aspect for achieving the above object is a computer program that causes a control device to control the operation of a charge/discharge circuit included in a capacitance detection unit that detects the capacitance between an electrode and an object, ,
By executing the computer program, the control device
Acquiring a first detected capacitance, which is the capacitance detected by operating the charge/discharge circuit at the first frequency,
acquire a first reference capacitance corresponding to a reference capacitance for determining whether or not the object is operated;
Based on the amount of change in the first detection capacitance from the first reference capacitance, determining whether or not the object is operated,
When it is determined that there is the operation, acquire a second detection capacitance that is the capacitance detected by operating the charge and discharge circuit at the second frequency,
generating a second reference capacitance based on reference information indicating the correlation between the first detection capacitance and the second detection capacitance;
The presence or absence of the operation is verified based on the second detection capacitance and the second reference capacitance.

ADVANTAGE OF THE INVENTION According to this invention, the touch sensor which can discriminate|determine operation to a target object correctly can be provided, even under a noisy environment, suppressing the increase in power consumption.

1 illustrates a functional configuration of a touch sensor according to one embodiment; 4 illustrates the operation of the touch sensor described above. An example of the flow of operation of the above touch sensor is shown. 4 shows another example of the flow of operation of the touch sensor described above. 4 shows another example of the flow of operation of the touch sensor described above.

Exemplary embodiments are described in detail below with reference to the accompanying drawings. FIG. 1 illustrates the functional configuration of a touch sensor 1 according to one embodiment.

The touch sensor 1 includes electrodes 11 . The electrode 11 is arranged so that a part of the user's body (such as the finger F) faces the object 2 on which a touch operation can be performed. Object 2 is a dielectric. The term “touch operation” used in this specification means an operation involving the approach or contact of a part of the user's body with respect to the object 2 .

The touch sensor 1 includes a capacitance detection section 12 . The capacitance detection unit 12 has a charging/discharging circuit 121 for detecting the capacitance between the electrode 11 and the object 2 .

The charge/discharge circuit 121 is electrically connected to the electrode 11 . The charging/discharging circuit 121 can perform charging and discharging operations. During the charging operation, the charging/discharging circuit 121 supplies the electrode 11 with a current supplied from a power source (not shown). During the discharge operation, the charge/discharge circuit 121 releases current from the electrode 11 .

An electric field is generated around the object 2 by the current supplied to the electrode 11 . When the user's finger F or the like approaches this electric field, a pseudo capacitor is formed between it and the electrode 11 . This increases the capacitance between the electrode 11 and the object 2 . As the capacitance increases, the current emitted from the electrode 11 increases during the discharge operation.

The touch sensor 1 has a control device 13 . The control device 13 includes a control section 131 . The control unit 131 has a function of controlling the operation of the charging/discharging circuit 121 . Control unit 131 operates charging/discharging circuit 121 at a specified frequency. The expression "operate the charging/discharging circuit at a specified frequency" used in this specification means to cause the charging/discharging circuit to repeat the charging operation and the discharging operation at the specified frequency.

The capacitance detection unit 12 has a conversion circuit 122 . A current emitted from the electrode 11 is input to the conversion circuit 122 . The conversion circuit 122 includes a circuit whose transmission frequency changes according to the amount of input current, and a counter that counts pulses output from the circuit. That is, the conversion circuit 122 outputs data having a numerical value corresponding to the amount of current corresponding to the detected capacitance.

The data is input to the control unit 131 . The controller 131 can acquire the capacitance between the electrode 11 and the object 2 based on the numerical value indicated by the data. In this way, the controller 131 causes the capacitance detector 12 to detect the capacitance between the electrode 11 and the object 2 .

Specifically, as exemplified in FIG. 2, the control unit 131 causes the capacitance detection unit 12 to repeatedly detect the capacitance between the electrode 11 and the object 2 at a specified period T1. Period T1 is, for example, 20 milliseconds. Capacitance detection is performed by control unit 131 operating charging/discharging circuit 121 at the first frequency. The capacitance between the electrode 11 and the object 2 detected by operating the charging/discharging circuit 121 at the first frequency is called a first detected capacitance C1. The first frequency is, for example, 6 MHz.

As illustrated in FIG. 1 , the control device 13 has a storage section 132 . The storage unit 132 stores reference information. The reference information includes a first reference capacitance Cr1 and a second reference capacitance Cr2. The first reference capacitance Cr1 is a capacitance value that serves as a reference for determining whether a touch operation has been performed on the object 2 based on the first detection capacitance C1. The second reference capacitance Cr2 is charged at the second frequency under the same conditions as when the first reference capacitance Cr1 was obtained (a state in which a touch operation is performed or a state in which no touch operation is performed). It is the capacitance value between the electrode 11 and the object 2 detected by operating the discharge circuit 121 . The first frequency and the second frequency are different. The second frequency is, for example, 1.5 MHz.

The reference information can be acquired under a noise-free environment and stored in the storage unit 132 before the touch sensor 1 is shipped from the factory. Alternatively, the reference information can be acquired and stored in the storage unit 132 when the touch sensor 1 is initially activated in the actual usage environment. Furthermore, the reference information can be acquired and stored in the storage unit 132 before the touch sensor 1 is shipped from the factory in a noise-free environment in which no touch operation is performed. Further, the reference information can be acquired and stored in the storage unit 132 under a noise-free environment before the touch sensor 1 is shipped from the factory while a touch operation is being performed.

When the user's finger F or the like approaches the object 2, the capacitance between the electrode 11 and the object 2 increases as described above. The control unit 131 determines that a touch operation has been performed on the object 2 when the amount of change in the first detection capacitance C1 from the first reference capacitance Cr1 exceeds the threshold value Cth. In the illustrated example, it is not determined that the object 2 has been touched based on the first detection capacitance C1 acquired at time t1. At time t2, it is determined that the touch operation has been performed on the object 2 based on the acquired first detection capacitance C1.

In FIG. 2, the first reference capacitance Cr1 is described as if it takes a constant value. However, the first reference capacitance Cr1 is updated, for example, by a moving average value of a plurality of first detection capacitances C1 acquired over a defined period including the most recent first detection capacitance C1.

FIG. 3 shows an example of the operation of the touch sensor 1 configured as described above for determining whether the object 2 has been touched.

The control unit 131 acquires the first detection capacitance C1 (STEP 1). Specifically, the control unit 131 operates the charging/discharging circuit 121 at the first frequency and receives an input digital signal corresponding to the first detection capacitance C1 from the conversion circuit 122 .

Subsequently, the control unit 131 monitors the value of the input digital signal and determines whether or not a touch operation has been performed on the object 2 (STEP 2). As described above, when the amount of change in the first detection capacitance C1 from the first reference capacitance Cr1 exceeds the specified threshold value Cth, the control unit 131 determines that the touch operation has been performed on the object 2. do. If the amount of change in the first detected capacitance C1 from the first reference capacitance Cr1 is equal to or less than the threshold value Cth (NO in STEP2), the process returns to STEP1, and the first detected capacitance C1 is obtained. .

When it is determined that a touch operation has been performed on object 2 based on the charge/discharge operation at the first frequency (YES in STEP 2), control unit 131 activates charge/discharge circuit 121 at a second frequency different from the first frequency. make it work. Thereby, the capacitance between the electrode 11 and the object 2 is detected based on the operation of the charging/discharging circuit 121 at the second frequency. This capacitance is called a second detection capacitance C2. The control unit 131 acquires the second detection capacitance C2 (STEP3). Specifically, the control unit 131 receives an input digital signal corresponding to the second detection capacitance C2 from the conversion circuit 122 .

In the example shown in FIG. 2, it is determined that the touch operation has been performed on the object 2 based on the first detection capacitance C1 acquired at time t2, so the second detection capacitance C2 is detected at time t3. has been acquired. A time interval T2 between time t2 and time t3 is, for example, 100 microseconds.

Subsequently, the control unit 131 acquires detection information (STEP 4). The detection information corresponds to the ratio between the first detection capacitance C1 and the second detection capacitance C2. A ratio is an example of a correlation.

Subsequently, the control unit 131 compares the detection information with reference information stored in the storage unit 132 to verify whether a touch operation has been performed on the object 2 (STEP 5). The reference information stored in the storage unit 132 also includes the ratio between the first reference capacitance Cr1 and the second reference capacitance Cr2. A ratio is an example of a correlation.

The difference between the ratio of the first detection capacitance C1 and the second detection capacitance C2 and the ratio of the first reference capacitance Cr1 and the second reference capacitance Cr2 is within a specified threshold range If there is (YES in STEP5), control unit 131 validates the previous determination that the touch operation was performed on object 2 (STEP6). A difference is an example of a degree of matching.

As illustrated in FIG. 1, the control device 13 is configured to output the detection signal S through an output interface (not shown). The detection signal S is a signal corresponding to determination that a touch operation has been performed on the object 2 . Detection signal S is output when control unit 131 finally determines that a touch operation has been performed on object 2 .

If the difference exceeds the threshold (NO in STEP5), control unit 131 determines that the change in capacitance is caused by environmental noise, and determines that the touch operation has been performed. (STEP 2) is invalidated (STEP 7). In this case, the detection signal S is not output.

Note that the control device 13 can be configured to also output a detection signal corresponding to the determination when it is finally determined that the touch operation has not been performed on the object 2 .

Detection of the capacitance between the electrode 11 and the object 2 using the two frequencies as described above can be performed to verify the determination that a touch operation has been performed. In other words, this is done to prevent erroneous detection of touch operations due to environmental noise. Environmental noise may also change the capacitance between the electrode 11 and the object 2 . Therefore, by monitoring only the first detection capacitance C1 detected by the operation of the charging/discharging circuit at the first frequency, it is possible to distinguish between an increase in capacitance due to touch operation and an increase in capacitance due to environmental noise. Sometimes you can't.

For example, when the cause of the capacitance change is the adhesion of water to the object 2, the value of the difference between the second detection capacitance C2 and the second reference capacitance Cr2 is the first detection capacitance C1 and It can be different from the difference value of the first reference capacitance Cr1. Since water has a higher electrical resistance value than the human body, it takes longer to fully charge the electrode 11 . That is, if the charging/discharging circuit 121 is operated at a higher frequency, discharge may occur before reaching the fully charged state. tend to be lower than those found in

Further, when the cause of the change in capacitance is environmental noise having frequency characteristics, the capacitance detected by charge/discharge circuit 121 operated at a frequency closer to the frequency of the environmental noise tends to fluctuate. Therefore, both difference values tend to be different.

The above description of the difference values is based on the premise that the update of the second reference capacitance Cr2 is always performed in the same manner as the first reference capacitance Cr1. However, in the present embodiment, acquisition of the second detection capacitance C2 is based on the difference between the first detection capacitance C1 and the first reference capacitance Cr1. only if Therefore, when acquiring the second detection capacitance C2, there is no second reference capacitance Cr2 for acquiring the difference.

Therefore, in this embodiment, detection information indicating the correlation between the first detection capacitance C1 and the second detection capacitance C2 is used. In the state where the electrode 11 is fully charged, the correlation value between the first reference capacitance Cr1 and the second reference capacitance Cr2 when no touch operation is performed is the first detection value when the touch operation is performed. It roughly matches the correlation value between the capacitance C1 and the second detection capacitance C2. On the other hand, if moisture adheres to the object 2 or environmental noise having frequency characteristics exists, the first detection capacitance C1 and the second detection capacitance C2 will differ for the reasons described above, resulting in a correlation value changes, and the detected information and the reference information are different. Therefore, by comparing the detected information with the reference information, it is possible to distinguish between a change in capacitance due to a touch operation and a change in capacitance due to environmental noise.

In order to accurately detect a touch operation, both the first detection capacitance C1 and the second detection capacitance C2 are always detected, and the first reference capacitance Cr1 and the second reference capacitance Cr2 are updated. is preferred to continue. However, such a configuration suffers from increased power consumption. According to the configuration of this embodiment, only when it is determined that a touch operation has been performed based on the operation of the charge/discharge circuit 121 at the first frequency, verification based on the operation of the charge/discharge circuit 121 at the second frequency is performed. is performed. Since the frequency of driving the charge/discharge circuit 121 at the second frequency can be reduced, an increase in power consumption of the touch sensor 1 can be suppressed. Therefore, it is possible to accurately determine a touch operation even in a noisy environment while suppressing an increase in power consumption.

In particular, by taking the ratio of the first detection capacitance C1 and the second detection capacitance C2 as the detection information and comparing it with the ratio of the first reference capacitance Cr1 and the second reference capacitance Cr2 as the reference information, , it is possible to perform verification that is not easily affected by various environmental factors.

The time interval T2 from the detection of the first detection capacitance C1 to the detection of the second detection capacitance C2 is sufficiently shorter than the period T1 in which the detection of the first detection capacitance C1 is repeated. is preferred. Since the speed of change in capacitance due to environmental noise is sufficiently faster than the speed of change in capacitance due to touch operation, with this configuration, the change in capacitance due to environmental noise and the static capacitance due to touch operation can be minimized. It is possible to easily identify changes in electric capacity.

As illustrated in FIG. 3, after it is verified that the touch operation has been performed in STEP 6, the control unit 131 can update the reference information stored in the storage unit 132 with the detection information used for verification. (STEP8).

As described with reference to FIG. 2, the control unit 131 determines whether the amount of change in the first detection capacitance C1 from the first reference capacitance Cr1 exceeds the specified threshold value Cth. 2 is determined whether a touch operation has been performed. As described above, the first reference capacitance Cr1 is updated each time the first detected capacitance C1 is obtained, so the first reference capacitance Cr1 may fluctuate due to environmental factors. Depending on the degree of variation of the first reference capacitance Cr1, the reference information stored in the storage unit 132 may not be suitable as an index for verification. The detection information used when the touch operation is performed has a high probability of reflecting the actual usage state. By using this detection information as reference information in the next verification, it is possible to easily avoid the situation where the verification result is affected by environmental factors.

As illustrated in FIG. 3, when it is determined that the touch operation has not been performed on the object 2 based on the operation of the charging/discharging circuit 121 at the first frequency (NO in STEP2), the control unit 131 The process illustrated in FIG. 4 may be performed.

Specifically, the control unit 131 determines whether a prescribed time has passed since it was determined that the touch operation was not performed (STEP 9). If the specified time has not elapsed (NO in STEP9), the process returns to STEP1 in FIG. The defined time is, for example, 1 minute.

When it is determined that the specified time has passed (YES in STEP9), the control section 131 acquires the second detection capacitance C2 (STEP10).

Subsequently, the control unit 131 acquires detection information in the same manner as in STEP 4 (STEP 11), and updates the reference information stored in the storage unit 132 with the acquired detection information (STEP 12).

As described above, the first reference capacitance Cr1 used to determine whether a touch operation has been performed may vary depending on environmental factors. Depending on the degree of variation of the first reference capacitance Cr1, the reference information stored in the storage unit 132 may not be suitable as an index for verification. According to the above configuration, it is possible to periodically update the reference information so as to reflect the most recent environmental factors. This makes it easier to avoid situations in which the verification results are affected by environmental factors.

As exemplified in FIG. 4, the control unit 131 can determine whether detection has been performed a specified number of times after the second detection capacitance C2 is obtained in STEP 10 (STEP 13). The specified number of times is, for example, 10 times. If it is determined that the number of detections has not reached the prescribed number (NO in STEP 13), the process returns to STEP 1, and the first detected capacitance C1 is obtained.

When it is determined that the touch operation has not been performed on the object 2 based on the first detection capacitance C1 (NO in STEP 2), it is determined whether the specified time has passed (STEP 9), and the second detection capacitance C1 is determined. Acquisition of the capacitance C2 (STEP 10) and determination of whether or not detection has been performed a specified number of times (STEP 13) are performed again. When it is determined that the number of times detection has been performed has reached the specified number (YES in STEP 13), control unit 131 detects the plurality of first detection capacitances C1 and the plurality of capacitances C1 detected so far. A statistical value is obtained for each of the second detection capacitances C2 (STEP 14). Examples of statistical values include mean, median, mode, and the like.

Subsequently, the control unit 131 acquires detection information based on the statistical value of the first detection capacitance C1 and the statistical value of the second detection capacitance C2 (STEP11). For example, the sensing information can be the ratio of the first sensing capacitance statistic and the second sensing capacitance statistic. Furthermore, the control unit 131 updates the reference information stored in the storage unit 132 with the acquired detection information (STEP 12).

According to such a configuration, it is possible to prevent the detection information used for updating the reference information from being affected by environmental factors accompanied by short-term changes. Therefore, it is possible to more easily avoid a situation in which the verification result is affected by environmental factors.

FIG. 5 shows another example of processing executed by the control unit 131 . Steps that are substantially the same as the steps illustrated in FIG. 3 are given the same reference numerals, and repeated descriptions are omitted.

In this example, when the second detection capacitance C2 is acquired based on the determination that the touch operation is performed through the acquisition of the first detection capacitance C1, the control unit 131 controls the second reference capacitance A capacitance Cr2 is generated (STEP 21). For example, the second reference capacitance Cr2 is calculated by multiplying the first reference capacitance Cr1 used in STEP2 by a prescribed coefficient. The coefficient corresponds to the ratio of the first reference capacitance Cr1 and the second reference capacitance Cr2. A ratio is an example of a correlation. The coefficient is an example of reference information. The second reference capacitance Cr2 may be calculated by multiplying the first detection capacitance C1 obtained in STEP1 by a prescribed coefficient.

The reference information can be acquired under a noise-free environment and stored in the storage unit 132 before the touch sensor 1 is shipped from the factory. Alternatively, the reference information can be acquired and stored in the storage unit 132 when the touch sensor 1 is initially activated in the actual usage environment. Furthermore, the reference information can be acquired and stored in the storage unit 132 before the touch sensor 1 is shipped from the factory in a noise-free environment in which no touch operation is performed. Further, the reference information can be acquired and stored in the storage unit 132 under a noise-free environment before the touch sensor 1 is shipped from the factory while a touch operation is being performed.

Subsequently, the control unit 131 determines whether the difference between the second detection capacitance C2 obtained in STEP2 and the second reference capacitance Cr2 generated in STEP21 is equal to or less than a predetermined threshold (STEP22). If the difference is greater than the threshold (YES in STEP22), control unit 131 validates the previous determination that the touch operation has been performed on object 2 (STEP6). If the difference is equal to or less than the threshold (NO in STEP 22), control unit 131 determines that the change in capacitance is caused by environmental noise, and determines that a touch operation has been performed. is invalidated (STEP7).

As described above, when the electrode 11 is fully charged, the correlation value between the first reference capacitance Cr1 and the second reference capacitance Cr2 when no touch operation is performed is It roughly matches the correlation value between the first detection capacitance C1 and the second detection capacitance C2 in the case. Therefore, based on the reference information corresponding to the correlation value, the second reference capacitance Cr2 necessary for verifying that the touch operation has been performed can be generated from the second detection capacitance C2. Thereby, acquisition of the second detection capacitance C2 is performed only when it is determined that a touch operation has been performed on the object 2 based on the difference between the first detection capacitance C1 and the first reference capacitance Cr1. Sometimes, the problem that the second reference capacitance Cr2 does not exist can be overcome. Therefore, it is possible to accurately determine a touch operation even in a noisy environment while suppressing an increase in power consumption by reducing the frequency of driving the charging/discharging circuit 121 at the second frequency.

The touch sensor 1 having the configuration as described above can be incorporated in, for example, a door handle that is a part of a vehicle. A door handle is an example of an object. In this case, when it is determined that the user's finger F or the like has touched the door handle, the control device 13 outputs the detection signal S. FIG. The detection signal S can be sent to, for example, a vehicle door lock. The locking device can lock and unlock the door according to the detection signal S.

The functions of the control unit 131 described above can be implemented by a dedicated integrated circuit such as a microcontroller, ASIC, or FPGA that can execute a computer program that implements the processes described above. The controller 131 may be realized by a general-purpose microprocessor operating in cooperation with a general-purpose memory. A CPU, MPU, and GPU can be exemplified as a general-purpose microprocessor. Examples of general-purpose memory include ROM and RAM. In this case, the ROM may store a computer program for executing the above-described process. The general-purpose microprocessor designates at least part of the program stored on the ROM, develops it on the RAM, and cooperates with the RAM to execute the above-described processing. The controller 131 may be implemented by a combination of a general-purpose microprocessor and a dedicated integrated circuit.

The functions of the storage unit 132 described above can be realized by a storage device such as a semiconductor memory or a hard disk device. At least part of the general-purpose memory described above may be used as the storage unit 132 . The control unit 131 and the storage unit 132 may be provided as a plurality of elements independent of each other, or may be packaged in a single element.

The above embodiments are merely examples for facilitating understanding of the present invention. The configurations according to the above embodiments can be modified and improved as appropriate without departing from the scope of the present invention.

In the above embodiment, for each of the reference information and the detection information, the capacitance value detected based on the operation of the charging/discharging circuit 121 at the first frequency and the operation of the charging/discharging circuit 121 at the second frequency A ratio of the capacitance values detected based on is used. However, a difference between both values, a correlation coefficient, or the like may be used as long as the correlation between the two values can be shown.

In the above-described embodiment, it is verified whether or not a touch operation has been performed on the object 2 based on whether the difference between the reference information and the detection information is within a specified threshold range. Depending on the aspects of the reference information and the detection information, an appropriate index representing the degree of matching between the two can be used to verify whether or not the target object 2 has been touched.

The main purpose of the processing illustrated in FIG. 4 is to maintain the quality of the reference information as an index used for verifying the touch operation even while the touch operation is not performed on the object 2 . The process can also be configured to be executed when a malfunction in the operation of the touch sensor 1 is suspected. For example, if touch operations are detected excessively frequently within a specified period of time, it is expected that there is some problem in the reference information used to distinguish between touch operations and environmental noise. In such a case, the reference information can be corrected appropriately by executing the processing illustrated in FIG. Alternatively, in the case where the touch sensor 1 is built into the door handle of the vehicle, if the door is locked or unlocked by the smart key entry system, it is expected that the locking or unlocking through the touch sensor 1 will not function. be. In such a case, the functions of the touch sensor 1 can be restored by executing the processing illustrated in FIG.

Processing indicated by broken lines in the flow charts illustrated in FIGS. 3 and 4 can be omitted.

The touch sensor 1 can be arranged at locations other than the door handle in the vehicle. A touch operation detected by touch sensor 1 does not necessarily have to be performed with finger F of the user. Touch operations using body parts such as palms, elbows, knees, and toes can also be detected.

The touch sensor 1 can be used for any user interface that requires detection of touch operations by a user. Examples of devices equipped with such a user interface include building air-conditioning equipment, building light control equipment, audio-visual equipment used indoors or outdoors, cooking equipment, air-conditioning equipment, toys, and the like.

1: Touch sensor, 2: Object, 11: Electrode, 12: Capacitance detection unit, 121: Charge/discharge circuit, 13: Control device, 131: Control unit, 132: Storage unit, C1: First detection electrostatic Capacitance, C2: second detection capacitance, Cr1: first reference capacitance, Cr2: second reference capacitance

Claims (11)

an electrode;
a capacitance detection unit having a charging/discharging circuit for detecting the capacitance between the electrode and the object;
a control unit that controls the operation of the charging/discharging circuit;
A first detected capacitance, which is the capacitance detected by operating the charge/discharge circuit at a first frequency, and a first detected capacitance detected by operating the charge/discharge circuit at a second frequency different from the first frequency. A storage unit that stores reference information indicating a correlation with the second detection capacitance that is the capacitance that is detected;
and
The control unit
obtaining the first sensed capacitance;
Acquiring a first reference capacitance corresponding to a reference capacitance for determining whether the object is operated or not;
Based on the amount of change of the first detection capacitance from the first reference capacitance, determining whether or not the object is operated,
When it is determined that there is the operation, the second detection capacitance is obtained,
Comparing the detection information indicating the correlation between the first detection capacitance and the second detection capacitance with the reference information,
verifying the presence or absence of the operation based on the result of the comparison;
touch sensor. the correlation is the ratio of the first sensed capacitance to the second sensed capacitance,
The touch sensor according to claim 1. The control unit updates the reference information with the detection information.
The touch sensor according to claim 1 or 2. Detection of the second detection capacitance is performed after a specified time has passed since it is determined that there is no operation based on the first detection capacitance.
The touch sensor according to claim 3. The control unit acquires the detection information based on statistical values obtained from the plurality of first detection capacitances and statistical values obtained from the plurality of second detection capacitances.
The touch sensor according to claim 3 or 4. an electrode;
a capacitance detection unit having a charging/discharging circuit for detecting the capacitance between the electrode and the object;
a control unit that controls the operation of the charging/discharging circuit;
and
The control unit
Acquiring a first detected capacitance, which is the capacitance detected by operating the charge/discharge circuit at a first frequency,
Acquiring a first reference capacitance corresponding to a reference capacitance for determining whether the object is operated or not;
Based on the amount of change of the first detection capacitance from the first reference capacitance, determining whether or not the object is operated,
When it is determined that there is the operation, obtaining a second detection capacitance that is the capacitance detected by operating the charging and discharging circuit at a second frequency different from the first frequency,
generating a second reference capacitance based on reference information indicating a correlation between the first detection capacitance and the second detection capacitance;
Verifying the presence or absence of the operation based on the second detection capacitance and the second reference capacitance;
touch sensor. the object is part of a vehicle,
The touch sensor according to any one of claims 1 to 6. a control unit for controlling the operation of a charge/discharge circuit included in a capacitance detection unit that detects the capacitance between an electrode and an object;
A first detected capacitance, which is the capacitance detected by operating the charge/discharge circuit at a first frequency, and a first detected capacitance detected by operating the charge/discharge circuit at a second frequency different from the first frequency. A storage unit that stores reference information indicating a correlation with the second detection capacitance that is the capacitance that is detected;
and
The control unit
obtaining the first sensed capacitance;
Acquiring a first reference capacitance corresponding to a reference capacitance for determining whether the object is operated or not;
Based on the amount of change of the first detection capacitance from the first reference capacitance, determining whether or not the object is operated,
When it is determined that there is the operation, the second detection capacitance is obtained,
Comparing the detection information indicating the correlation between the first detection capacitance and the second detection capacitance with the reference information,
verifying the presence or absence of the operation based on the result of the comparison;
Control device. A control device that controls the operation of a charge/discharge circuit included in a capacitance detection unit that detects the capacitance between an electrode and an object,
Acquiring a first detected capacitance, which is the capacitance detected by operating the charge/discharge circuit at a first frequency,
Acquiring a first reference capacitance corresponding to a reference capacitance for determining whether the object is operated or not;
Based on the amount of change of the first detection capacitance from the first reference capacitance, determining whether or not the object is operated,
When it is determined that there is the operation, obtaining a second detection capacitance that is the capacitance detected by operating the charging and discharging circuit at a second frequency different from the first frequency,
generating a second reference capacitance based on reference information indicating a correlation between the first detection capacitance and the second detection capacitance;
Verifying the presence or absence of the operation based on the second detection capacitance and the second reference capacitance;
Control device. The operation of a charging/discharging circuit included in the electrostatic capacitance that detects the electrostatic capacitance between the electrode and the object is the electrostatic capacitance detected by operating the charging/discharging circuit at a first frequency. Storing reference information indicating a correlation between one detection capacitance and a second detection capacitance, which is the capacitance detected by operating the charging/discharging circuit at a second frequency different from the first frequency A computer program that causes a control device that cooperates with a storage device to control,
By executing the computer program, the control device
detecting the first detection capacitance;
acquire a first reference capacitance corresponding to a reference capacitance for determining whether or not the object is operated;
determining whether or not the object is operated based on the amount of change in the first detection capacitance from the first detection capacitance;
When it is determined that there is the operation, acquire the second detection capacitance,
Compare the detection information indicating the correlation between the first detection capacitance and the second detection capacitance with the reference information,
verifying whether or not the operation has been performed based on the result of the comparison;
computer program. A computer program that causes a control device to control the operation of a charge/discharge circuit included in a capacitance detection unit that detects the capacitance between an electrode and an object,
By executing the computer program, the control device
Acquiring a first detected capacitance, which is the capacitance detected by operating the charge/discharge circuit at a first frequency,
acquire a first reference capacitance corresponding to a reference capacitance for determining whether or not the object is operated;
Based on the amount of change in the first detection capacitance from the first reference capacitance, determining whether or not the object is operated,
When it is determined that the operation is present, acquire a second detection capacitance that is the capacitance detected by operating the charging and discharging circuit at a second frequency different from the first frequency,
generating a second reference capacitance based on reference information indicating the correlation between the first detection capacitance and the second detection capacitance;
Based on the second detection capacitance and the second reference capacitance, verify the presence or absence of the operation,
computer program.

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