JP2017017677A - Touch detection device for use in plumbing tool, and faucet device including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a touch detection device which can be operated by light touch, and can prevent malfunction even when it is used in a plumbing tool.SOLUTION: A touch detection device for use in a plumbing tool has a detection part (2d) for detecting contact of an object, a vibration exciting element (4) attached to the detection part (2d), a drive circuit (18) for exciting vibration in the detection part (2d), by applying an AC voltage of a predetermined frequency to the vibration exciting element (4) intermittently, and a contact determination circuit (16a) for determining whether or not an object has touched the detection part (2d), based on the vibration of the detection part after application of an AC voltage to the vibration exciting element (4) by the drive circuit (18) has stopped.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a touch detection device, and more particularly, to a touch detection device used for a watering device and a faucet device including the touch detection device.

  Water-based devices that can detect an operation by a user using a switch or a sensor and can switch between water discharge and water stop or change the water discharge form based on the detected operation are becoming popular. Water-related appliances such as faucet devices used around water such as kitchens, washrooms, toilets, bathrooms, etc. are used in an environment that is prone to getting wet. Years are required. For this reason, it is desirable that switches and sensors for detecting operations do not have mechanical electrical contacts.

Photoelectric sensors used in automatic faucets, etc. have the advantage that they can be operated without contact, but they are slow in response, inconvenient to use, and the detector is conspicuous, so it can be said that the design is also excellent. Absent. Furthermore, the photoelectric sensor also has a problem that it malfunctions when water or bubbles adhere to the detection unit.
In addition, the electrostatic sensor can be operated with a very light touch, but malfunction is unavoidable in an environment where the sensor is easily wetted with water, and it is difficult to use it for a water-related device.

Here, Japanese Unexamined Patent Publication No. 54-153284 (Patent Document 1) describes a piezoelectric switch. This piezoelectric switch is a switch using a piezoelectric element, and can detect a pressing operation of a user without using a mechanical electrical contact.
Japanese Patent Publication No. 58-40803 (Patent Document 2) describes a contactless pushbutton switch circuit. Also in this pushbutton switch, the pressing operation of the user is detected using a piezoelectric element without using mechanical electrical contacts.

JP 54-153284 A Japanese Patent Publication No. 58-40803

  However, in the piezoelectric switch described in Japanese Patent Laid-Open No. 54-153284 (Patent Document 1), the piezoelectric element is elastically deformed by applying a pressing force, and the switch operation is detected by the electric charge generated based on the elastic deformation. Therefore, a relatively large operating force is required to operate the switch, and there is a problem that it cannot be operated with a light touch.

  Further, the non-contact pushbutton switch circuit described in Japanese Patent Publication No. 58-40803 (Patent Document 2) has a piezoelectric element incorporated in an oscillation circuit, and a pressing force is applied to the piezoelectric element. The user's pressing operation is detected by utilizing the fact that the electrical characteristics such as the impedance change and the oscillation decreases or stops. In this contactless pushbutton switch circuit, the electrical characteristics change even with a slight pressing force on the piezoelectric element, and the oscillation state of the oscillation circuit incorporating the piezoelectric element changes. Therefore, the operation can be detected even with a light touch. be able to. However, since the oscillation state of the oscillation circuit is extremely sensitive to circuit constants, if a piezoelectric element for detecting the operation is installed at a location away from the oscillation circuit body, the oscillation state becomes unstable and false detection is likely to occur. There's a problem.

  For example, only the piezoelectric element incorporated in the oscillation circuit is arranged near the water discharge part of the faucet device, and the other part of the oscillation circuit (oscillation circuit main body) is arranged below the counter board where the faucet device is installed. In this case, the lead wire connecting the piezoelectric element and the oscillation circuit body is relatively long. For this reason, the inductance and stray capacitance component of this lead wire may make the operation of the oscillation circuit unstable and cause malfunction. In order to prevent such a malfunction, it is necessary to dispose the piezoelectric element in the vicinity of the oscillation circuit body. In this case, for example, in order to arrange the operation unit in the vicinity of the water discharge unit of the water faucet device, it is necessary to incorporate the entire oscillation circuit in the vicinity of the water discharge unit, which greatly restricts the degree of freedom of design of the water faucet device. It will be.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a touch detection device that can be operated with a light touch and that can prevent malfunction even when used in a water-related device, and a water faucet device including the touch detection device. It is said.

  In order to solve the above-described problems, the present invention provides a touch detection device used for a water-related apparatus, a detection unit that detects contact of an object, a vibration excitation element attached to the detection unit, By intermittently applying an AC voltage of a predetermined frequency to the vibration excitation element, a drive circuit for exciting vibration to the detection unit, and a detection unit after the application of the AC voltage to the vibration excitation element by the drive circuit is stopped And a contact determination circuit that determines whether or not the object has contacted the detection unit based on the vibration.

  In the present invention configured as described above, an AC voltage having a predetermined frequency is intermittently applied to the vibration excitation element by the drive circuit, and vibration is excited in the detection unit to which the vibration excitation element is attached. The contact determination circuit determines whether or not the object has contacted the detection unit based on the vibration of the detection unit after the application of the AC voltage to the vibration excitation element is stopped.

  According to the present invention configured as described above, since the contact of the object with the detection unit is determined based on the vibration of the detection unit after the application of the alternating voltage is stopped, the light “touch” to the detection unit is determined. ”Also causes a change in the vibration of the detection unit, and“ touch ”can be reliably detected. In addition, since the vibration excitation element is attached to the detection unit so as to excite vibration, even when the vibration excitation element is arranged at a location away from the drive circuit or the contact determination circuit, the circuit becomes unstable. There is no malfunction. Thereby, it becomes possible to arrange | position a drive circuit, a contact determination circuit, etc. freely, and it becomes possible to comprise the water implement with high design property.

  In the present invention, preferably, the vibration excitation element is configured by a piezoelectric element, and the contact determination circuit is based on an output signal from the vibration excitation element after the application of the AC voltage to the vibration excitation element is stopped. It is determined whether or not an object has contacted the detection unit.

  According to the present invention configured as described above, since the vibration excitation element is configured by a piezoelectric element, the vibration excitation element can be configured with a simple structure. Further, the contact determination circuit determines contact of the object with the detection unit based on an output signal from the vibration excitation element that is a piezoelectric element, so that an element or device for detecting the vibration of the detection unit is separately provided. Therefore, the vibration of the detection unit can be detected, and the configuration of the touch detection device can be simplified.

  In the present invention, preferably, the vibration excitation element includes an input terminal to which an AC voltage is applied by a drive circuit, and an output signal from the vibration excitation element is obtained from an input terminal of the vibration excitation element, and is output from the drive circuit. Becomes high impedance after the application of AC voltage is stopped.

  According to the present invention configured as described above, since the output signal is acquired from the input terminal that applies the AC voltage to the vibration excitation element, at least one of the wiring that applies the AC voltage and the wiring that acquires the output signal. The parts can be made common and the wiring of the signal lines can be simplified. In addition, since the output of the drive circuit becomes high impedance after the application of AC voltage is stopped, a sufficiently accurate output signal can be obtained even when the impedance of the output signal from the vibration excitation element is high.

  In the present invention, preferably, the contact determination circuit is configured to determine whether or not the object has contacted the detection unit based on the vibration energy of the detection unit after the application of the AC voltage by the drive circuit is stopped. When the energy is equal to or lower than a predetermined threshold value, it is determined that the object has touched.

  According to the present invention configured as described above, the contact determination circuit detects the touch based on the vibration energy of the detection unit after the application of the AC voltage is stopped. Therefore, a highly sensitive touch detection device can be configured.

  In the present invention, preferably, the contact determination circuit is configured to determine whether or not the object has contacted the detection unit based on the vibration amplitude of the detection unit after the application of AC voltage by the drive circuit is stopped, and the vibration When the time until the amplitude is attenuated to a predetermined amplitude or less is less than the predetermined time, it is determined that the object has touched.

  According to the present invention configured as described above, the contact determination circuit detects a touch based on the time until the vibration amplitude is attenuated to a predetermined amplitude or less, and therefore detects vibration attenuation with a simple circuit. The cost of the touch detection device can be reduced.

  In the present invention, preferably, the contact determination circuit is configured to determine whether or not the object has contacted the detection unit based on the vibration amplitude of the detection unit after the application of AC voltage by the drive circuit is stopped. After the application of the AC voltage is stopped by the circuit, it is determined that the object has been in contact when the vibration amplitude after a predetermined time has attenuated to a predetermined amplitude or less.

  According to the present invention configured as described above, the contact determination circuit detects the touch based on the vibration amplitude after the lapse of a predetermined time after the application of the AC voltage is stopped, and thus detects vibration attenuation with a simple circuit. And the cost of the touch detection device can be reduced.

  In the present invention, preferably, the contact determination circuit includes an abnormality detection circuit for preventing erroneous detection, and the abnormality detection circuit is based on an output signal from the vibration excitation element during application of an AC voltage to the vibration excitation element. To detect abnormalities.

  According to the present invention configured as described above, the abnormality detection circuit detects an abnormality based on the output signal during application of the alternating voltage to the vibration excitation element, so that the touch detection process is not complicated. Abnormalities can be detected and the occurrence of erroneous detection can be suppressed.

  In the present invention, preferably, the abnormality detection circuit detects an abnormality when the amplitude of the output signal during application of the alternating voltage to the vibration excitation element is larger than the amplitude at the normal time, and the contact determination circuit detects the abnormality. When it is detected, it is not determined that the object has touched.

  According to the present invention configured as described above, the abnormality detection circuit detects an abnormality based on the amplitude of the output signal during application of the AC voltage, and does not detect the contact of the object when the abnormality is detected. Therefore, even when water droplets or the like adhere to the detection unit, the occurrence of abnormality can be detected with simple signal processing, and malfunction due to erroneous detection can be prevented.

  In the present invention, preferably, the abnormality detection circuit detects an abnormality when the amplitude of the output signal fluctuates by a predetermined value or more during application of the AC voltage to the vibration excitation element, and the contact determination circuit detects the abnormality. If it does, it is not determined that the object has touched.

  According to the present invention configured as described above, the abnormality detection circuit detects an abnormality based on the fluctuation of the amplitude of the output signal during the application of the AC voltage, and thus can reliably detect the occurrence of the abnormality. It is possible to prevent malfunction due to erroneous detection.

  In the present invention, preferably, it further includes a contact determination confirmation circuit, and this contact determination confirmation circuit further reduces the possibility of false detection after it is once determined by the contact determination circuit that the object has contacted. Execute the contact determination confirmation operation.

  According to the present invention configured as described above, the contact determination confirmation circuit performs the contact determination confirmation operation after the contact determination circuit once determines the contact of the object, and thus more reliably prevents erroneous detection. be able to. In addition, since the contact determination operation is executed after the contact of the object is once determined by the contact determination circuit, it is possible to prevent the contact determination operation from being performed wastefully in a situation where there is no possibility of erroneous detection. Can do.

  In the present invention, preferably, the contact determination confirmation circuit applies an AC voltage to the vibration excitation element for a predetermined confirmation period longer than the application of a normal AC voltage as the contact determination confirmation operation, and from the vibration excitation element during the confirmation period. Based on the output signal, the contact determination by the contact determination circuit is confirmed.

  According to the present invention configured as described above, in the contact determination confirmation operation, an AC voltage is applied to the vibration excitation element for a predetermined confirmation period longer than normal, so that an abnormality during application of the AC voltage can be more reliably detected. Can be detected.

  In the present invention, preferably, it further includes a frequency adjustment circuit that adjusts the frequency of the AC voltage applied to the vibration excitation element, and this frequency adjustment circuit is applied to a frequency at which the detection unit attached with the vibration excitation element resonates. Adjust the AC voltage frequency.

  According to the present invention configured as described above, the frequency adjustment circuit adjusts the frequency of the AC voltage to be applied to a frequency at which the detection unit attached with the vibration excitation element resonates. Thus, since the detection unit is excited at the resonance frequency, the detection unit can be vibrated with a large amplitude with a small excitation force, and the touch detection device can be operated with less energy consumption.

  In the present invention, it is preferable that the frequency adjustment circuit executes the application of the AC voltage for a predetermined time a plurality of times at different frequencies, and sets the frequency at which the amplitude of the output signal from the vibration excitation element after the application of the AC voltage is stopped is maximized. The frequency at which the detection unit to which the vibration excitation element is attached resonates is determined.

  According to the present invention configured as described above, the frequency of the AC voltage can be adjusted even after the detection unit and the vibration excitation element are assembled to the water-surrounding device, so even when the resonance frequency is shifted due to secular change, The frequency of the applied AC voltage can be adjusted to the resonance frequency.

  In the present invention, preferably, when there are a plurality of frequencies at which the amplitude of the output signal is maximized after the application of the AC voltage is stopped, the frequency adjusting circuit is connected to the vibration excitation element among the frequencies having the maximum amplitude. The frequency with the smallest fluctuation in the amplitude of the output signal during the application of the AC voltage is determined as the frequency at which the detection unit to which the vibration excitation element is attached resonates.

  According to the present invention configured as described above, the resonance frequency of the detection unit to which the vibration excitation element is attached can be automatically and reliably set with a simple algorithm.

  In the present invention, it is preferable that the frequency adjustment circuit further includes a frequency shift detection circuit that detects occurrence of a shift between the resonance frequency of the detection unit and the frequency of the AC voltage applied to the vibration excitation element. When a frequency shift is detected by the circuit, adjustment is performed so that the frequency of the AC voltage matches the resonance frequency of the detection unit.

  In the present invention, it is desirable that the frequency of the AC voltage applied to the vibration excitation element and the resonance frequency of the detection unit be sufficiently matched. However, the resonance frequency of the detection unit may change temporarily or permanently after the initial adjustment of the frequency of the AC voltage due to temperature change or secular change of the detection unit, and a deviation may occur between the two. If such a frequency shift occurs, the detection performance may not be sufficiently exhibited, or erroneous detection may occur. However, it is difficult for the user to find a frequency shift of the touch detection device. According to the present invention configured as described above, the frequency adjustment circuit includes a frequency deviation detection circuit that detects occurrence of deviation between the resonance frequency of the detection unit and the frequency of the AC voltage applied to the vibration excitation element. When the frequency deviation is detected by the frequency deviation detection circuit, adjustment is performed so that the frequency of the AC voltage matches the resonance frequency of the detection unit, so the frequency deviation is monitored and the touch detection device is always in a good state. Can be kept in.

  In the present invention, it is preferable that the frequency adjustment circuit adjusts the frequency when the state in which the frequency shift is detected by the frequency shift detection circuit continues for a predetermined frequency shift determination time.

  The resonance frequency of the detection unit may change permanently due to aging, but may change temporarily due to temperature change, such as hot water being applied to the detection unit. For this reason, if the frequency is adjusted immediately because there is a frequency shift between the resonance frequency of the detection unit and the frequency of the AC voltage, the frequency adjustment becomes difficult due to the change in the resonance frequency during the adjustment. On the contrary, there is a possibility that the amount of deviation is increased. According to the present invention configured as described above, the frequency adjustment circuit performs the frequency adjustment when the state in which the frequency deviation is detected by the frequency deviation detection circuit continues for a predetermined frequency deviation determination time or longer. Thus, automatic adjustment by the frequency adjustment circuit can be performed more reliably.

  In the present invention, preferably, when the resonance frequency of the detection unit is lower than the frequency of the alternating voltage applied to the vibration excitation element, the frequency deviation determination time is an alternating voltage applied to the vibration excitation element by the resonance frequency of the detection unit. It is set to be longer than when the frequency is higher.

  It has been found by the present inventor that the decrease in the resonance frequency of the detection unit is often caused by adhesion of water droplets to the detection unit. Such a frequency shift due to the adhesion of water droplets is likely to be resolved with the passage of time, and it is better not to immediately adjust even if a shift is detected. In addition, the situation where the resonance frequency of the detection unit is higher than the frequency of the AC voltage occurs in most cases when frequency adjustment is performed with water droplets attached in the past and the frequency of the AC voltage is reduced. Found by the inventor. In such a situation, it is desirable to immediately adjust the frequency. According to the present invention configured as described above, when the resonance frequency of the detection unit is lower than the frequency of the AC voltage applied to the vibration excitation element, the resonance frequency of the detection unit is vibration-excited. Since it is set longer than the case where the frequency is higher than the frequency of the AC voltage applied to the element, it is possible to effectively cope with a temporary change in the resonance frequency due to the adhesion of water droplets.

  In the present invention, preferably, the frequency adjustment circuit is configured to search for a resonance frequency of the detection unit within a predetermined frequency range, and the first adjustment mode and the second adjustment mode in which the frequency range to be searched is different. In the first adjustment mode, the resonance frequency is searched for in the first frequency range including the standard frequency of the detector, and in the second adjustment mode, the frequency of the current AC voltage is calculated. The resonance frequency is searched for within a second frequency range that is narrower than the first frequency range.

  The deviation of the resonance frequency of the detection unit occurs due to variations between individual detection units, adhesion of water droplets to the detection unit, and the like, and the magnitude of such deviation of the resonance frequency varies depending on the cause of the frequency deviation. It has been found by the present inventors. Moreover, since it cannot be used as a touch detection device during the operation of the frequency adjustment circuit, it takes inconvenience to the user if the frequency adjustment takes time. According to the present invention configured as described above, in the first adjustment mode, the resonance frequency is searched for in the first frequency range including the standard frequency of the detection unit, and in the second adjustment mode, the current Since the resonance frequency is searched for in the second frequency range that is narrower than the first frequency range, including the frequency of the AC voltage, the adjustment according to the cause of the occurrence of the frequency shift can be executed in a short time.

  In the present invention, it is preferable to further include a determination circuit that determines whether or not the frequency adjustment by the frequency adjustment circuit is successful. In the first adjustment mode, when the determination circuit determines that the frequency adjustment has failed, the frequency adjustment is performed. In the second adjustment mode, the frequency of the current AC voltage is maintained without repeating the search for the resonance frequency when the determination circuit determines that the frequency adjustment has failed. Is done.

  According to the present invention configured as described above, in the first adjustment mode, when the frequency adjustment fails, the resonance frequency is repeatedly searched for until it succeeds, and in the second adjustment mode, the frequency adjustment fails. In this case, the frequency of the current AC voltage is maintained without repeating the search for the resonance frequency, so that appropriate frequency adjustment can be performed according to the occurrence of frequency deviation and the usage status of the touch detection device. Thus, it is possible to achieve both a reliable frequency adjustment and a reduction in the unusable period.

  In the present invention, preferably, the frequency adjustment circuit applies an AC voltage to the vibration excitation element for a plurality of frequencies within a predetermined frequency range, and acquires an output signal from the vibration excitation element when the AC voltage is applied. The frequency adjustment is performed by analyzing the detection waveform of these output signals, and the determination circuit includes a detection waveform whose waveform does not monotonously decrease after the application of the AC voltage is completed. If it is, it is determined that the frequency adjustment by the frequency adjustment circuit has failed.

  The reverberation vibration waveform after application of the AC voltage is a damped vibration waveform with a large initial amplitude and a gradually decreasing amplitude. However, if the acquired waveform contains large noise or something touches the detector. In this case, the damped oscillation waveform is disturbed, and the detected waveform does not become a monotonously decreasing waveform. According to the present invention configured as described above, when the detected waveform includes a waveform whose waveform does not monotonously decrease after the application of the AC voltage is completed, the frequency adjustment by the frequency adjustment circuit has failed. Since the determination is made, erroneous frequency adjustment due to the influence of noise or the like can be prevented.

  In the present invention, preferably, the frequency adjustment circuit applies an AC voltage to the vibration excitation element for a plurality of frequencies within a predetermined frequency range, and acquires an output signal from the vibration excitation element when the AC voltage is applied. The determination circuit is configured to search and determine the resonance frequency based on these output signals, and the determination circuit sets the vibration energy of the detection unit after stopping the application of the alternating voltage of the determined resonance frequency to a predetermined threshold value. If not, it is determined that the frequency adjustment by the frequency adjustment circuit has failed.

  In the situation where the frequency of the AC voltage to be applied and the resonance frequency of the detection unit are in good agreement, the detection unit is excited at the resonance frequency, so that the detection unit vibrates greatly, and the reverberation after the application of the AC voltage is completed. The vibration energy also increases. However, when a large amount of water droplets are attached to the detection unit that is adjusting the frequency, or when frequency adjustment is performed in a state where an object is in contact with the detection unit, the energy of reverberation vibration is reduced. Thus, there is a high possibility that a large error is included in the resonance frequency searched in a state where sufficient reverberation vibration does not occur. According to the present invention configured as described above, the frequency adjustment by the frequency adjustment circuit fails when the vibration energy of the detection unit after stopping the application of the alternating voltage of the determined resonance frequency does not reach the predetermined threshold value. Therefore, it is possible to prevent erroneous frequency adjustment due to frequency adjustment in an inappropriate environment.

  In the present invention, it is preferable that the contact determination confirmation circuit has an AC voltage having a confirmation frequency different from the frequency of the normal AC voltage as a contact determination confirmation operation after the contact determination circuit once determines that the object has contacted. Is also applied to the vibration excitation element, and even when an AC voltage having a confirmation frequency is applied, if the contact determination circuit determines that the object is in contact, the determination of contact with the detection unit is confirmed.

  In the present invention, when the object comes into contact with the detection unit, the contact of the object is detected using a phenomenon in which the energy of reverberation vibration after the application of the alternating voltage is reduced. However, even when a deviation occurs between the frequency of the AC voltage to be applied and the resonance frequency of the detection unit, the detection unit cannot be sufficiently excited, so that the energy of reverberation vibration is reduced. The resonance frequency of the detection unit also changes when water droplets or the like adhere to the detection unit. As a result, the energy of reverberation vibration decreases, and there is a possibility that the detection object is erroneously detected as being in contact. According to the present invention configured as described above, as a contact determination confirmation operation, an alternating voltage having a confirmation frequency different from the frequency of a normal alternating voltage is applied to the vibration excitation element, and an alternating voltage having a confirmation frequency is applied. When the contact of the object is determined by the contact determination circuit, the determination of the contact with the detection unit is confirmed. For this reason, even when the contact determination circuit erroneously determines the contact of the object due to a frequency shift, the contact determination confirmation circuit excites with an alternating voltage having a confirmation frequency different from the frequency of the normal alternating voltage. Even when the resonance frequency is shifted, a large reverberation vibration is excited when the confirmation frequency is close to the resonance frequency, and erroneous detection due to the frequency shift can be effectively suppressed.

  Further, the present invention is a faucet device capable of switching between water discharge and water stop by a touch operation, and an object by the touch detection device of the present invention, an operation unit provided with a detection unit, and the touch detection device. And an on-off valve that is opened and closed based on contact determination to the detection unit.

  According to the touch detection device of the present invention and the faucet device including the touch detection device, it is possible to operate with a light touch and to prevent malfunction even when used in a water-related apparatus.

It is a block diagram showing a schematic structure of a faucet device of a 1st embodiment of the present invention. It is a circuit diagram showing a schematic structure of a touch detection device of a 1st embodiment of the present invention. It is sectional drawing which expands and shows the detection part provided in the front-end | tip part of the faucet device of 1st Embodiment of this invention. In the touch detection apparatus of 1st Embodiment of this invention, it is a figure which shows the typical output waveform of a piezoelectric element when the user is not touching a detection part. In the touch detection apparatus of 1st Embodiment of this invention, it is a figure which shows the typical output waveform of a piezoelectric element when a user touches a detection part. It is a main flow which shows the effect | action of the faucet device of 1st Embodiment of this invention. It is the time chart which showed an example of the effect | action of the faucet device of 1st Embodiment of this invention. It is a touch detection flow called as a subroutine from the main flow of FIG. It is a figure which shows an example of an output waveform in case the resonant frequency of a detection part has shifted | deviated slightly from the frequency of the alternating voltage applied. 7 is a flowchart showing a touch confirmation detection process called as a subroutine in step S6 of FIG. 6. It is a figure which shows an example of an output waveform at the time of a touch confirmation detection being performed in the state in which the resonant frequency of the detection part shifted | deviated slightly from the frequency of the alternating voltage applied. It is a flowchart which shows the frequency adjustment process called as a subroutine in step S1 of FIG. It is an example of an output waveform when the resonant frequency of a detection part and the frequency of the alternating voltage to apply differ large comparatively. It is an example of an output waveform in case the resonant frequency of a detection part and the frequency of the alternating voltage applied are shifted | deviated slightly. It is an example of an output waveform in case the resonant frequency of a detection part and the frequency of the alternating voltage applied are fully corresponded. 7 is a touch detection flow called as a subroutine from the main flow of FIG. 6 in the second embodiment of the present invention. In the touch detection apparatus of 2nd Embodiment of this invention, it is a figure which shows the typical output waveform of a piezoelectric element when the user is not touching the detection part. In the touch detection apparatus of 2nd Embodiment of this invention, it is a figure which shows the typical output waveform of a piezoelectric element when a user touches a detection part. It is a figure which shows an example of an output waveform in case the resonant frequency of a detection part has shifted | deviated slightly from the frequency of the alternating voltage applied. 7 is a touch confirmation detection flow called as a subroutine from the main flow of FIG. 6 in the second embodiment of the present invention. It is a figure which shows an example of an output waveform at the time of a touch confirmation detection being performed in the state in which the resonant frequency of the detection part shifted | deviated slightly from the frequency of the alternating voltage applied. It is a circuit diagram which shows schematic structure of the detection circuit in 3rd Embodiment of this invention. It is a main flow which shows the effect | action of the faucet device of 3rd Embodiment of this invention. It is a touch detection flow called as a subroutine from the main flow. It is a touch confirmation detection flow called as a subroutine from the main flow. It is a frequency initial adjustment flow executed by the frequency adjustment circuit. It is a resonance frequency confirmation flow called as a subroutine from the main flow. This is a resonance frequency detection flow called as a subroutine from the resonance frequency confirmation flow. It is a frequency readjustment flow of AC voltage called as a subroutine from the main flow. It is a detection waveform data acquisition flow called as a subroutine from the touch detection flow. It is a figure which shows an example of the detection waveform acquired. 5 is a time chart for explaining a process of determining “touch” determination and “touch” determination. 5 is a time chart for explaining a process of determining “touch” determination and “touch” determination. 5 is a time chart for explaining a process of determining “touch” determination and “touch” determination.

Next, a faucet device according to a first embodiment of the present invention will be described with reference to the accompanying drawings. The faucet device according to the present embodiment incorporates the touch detection device according to the first embodiment of the present invention, and the touch detection device can detect a user operation and switch between water discharge and water stoppage. It is configured to be able to.
FIG. 1 is a block diagram showing a schematic configuration of the faucet device of the present embodiment. FIG. 2 is a circuit diagram illustrating a schematic configuration of the touch detection device of the present embodiment. FIG. 3 is an enlarged cross-sectional view of a detection unit provided at the tip of the faucet device.

  As shown in FIG. 1, the faucet device 1 according to the first embodiment of the present invention includes a faucet body 2 attached on a counter board C, and a detection unit 2 a provided at the tip of the faucet body 2. And a piezoelectric element 4 that is a vibration excitation element attached to the detection unit 2 a and a hot and cold mixing valve 6 built in the base of the faucet body 2. Further, the faucet device 1 includes a solenoid valve for hot water 8a and a solenoid valve for water 8b, which are disposed on the lower side of the counter board C, and each switch between supply and stop of hot water and water, and these solenoid valves. A faucet controller 10 that controls the opening / closing of the faucet and a detection circuit 12 that sends a signal to the faucet controller 10 in response to an operation on the detection unit 2a. In the faucet device 1 of the present embodiment, the detection unit 2a, the piezoelectric element 4, and the detection circuit 12 constitute a touch detection device according to the first embodiment of the present invention.

  In the faucet device 1 of the present embodiment, the hot water solenoid valve 8a and the water solenoid valve 8b are opened and closed when the user lightly touches the detection unit 2a provided at the tip of the faucet body 2, It is comprised so that a water stop state and a water discharge state can be switched. Therefore, in this embodiment, the front-end | tip part of the faucet main body 2 in which the detection part 2a was provided functions as an operation part of the faucet device 1.

The faucet body 2 is a metal tubular member having a base portion that rises substantially vertically from the counter board C, and a horizontal portion that extends substantially horizontally from the tip of the base portion. Is provided.
The detection unit 2a is provided at the front end of the faucet body 2 so as to form a front end surface thereof, and detects whether an object such as a user's finger is in contact with the detection unit 2a. The signal is configured to be sent to the detection circuit 12. As will be described later, a piezoelectric element 4 is built in the detection unit 2a, and this piezoelectric element 4 is electrically connected to the detection circuit 12 by two signal lines 4a and 4b passed through the faucet body 2. It is connected.

  The hot water / mixing valve 6 is built in the base of the faucet body 2 and has a hot water supply pipe 14a connected to the downstream side of the hot water solenoid valve 8a and a water supply pipe 14b connected to the downstream side of the water electromagnetic valve 8b. Connected to each. Moreover, a temperature control handle 6a is attached to the hot / cold water mixing valve 6. By adjusting the temperature control handle 6a, the mixing ratio of the hot water supplied from the hot water supply pipe 14a and the water supplied from the water supply pipe 14b is changed. It is set and the temperature of the hot water discharged from the water outlet 2b can be adjusted. Moreover, the hot water mixed in the hot / cold water mixing valve 6 is guided through a water passage member (not shown) disposed in the faucet body 2 and discharged from the water outlet 2b.

  The hot water solenoid valve 8 a and the water solenoid valve 8 b are solenoid valves that are opened and closed in response to a control signal from the faucet controller 10. The hot water solenoid valve 8a is connected to a pipe from a hot water heater (not shown), and is configured to flow hot water into the hot water pipe 14a when the valve is opened. The water solenoid valve 8b is connected to the water supply, and is configured to allow water to flow out to the water supply pipe 14b when the valve is opened.

The faucet controller 10 is configured to output control signals to the hot water solenoid valve 8a and the water solenoid valve 8b in accordance with an output signal from the detection circuit 12, and to open and close them.
The detection circuit 12 is configured to be electrically connected to the piezoelectric element 4 incorporated in the detection unit 2 a and to output a determination output signal to the faucet controller 10. The detection circuit 12 is configured to apply an alternating voltage to the piezoelectric element 4 to ultrasonically vibrate it at a predetermined frequency, and to acquire an output signal from a terminal of the piezoelectric element 4. Further, the detection circuit 12 determines whether or not the user's finger, which is the object, has touched (contacted) the detection unit 2a based on the output signal acquired from the piezoelectric element 4, and the determination result is output. It is configured to output to the faucet controller 10 as a signal.

  Specifically, the faucet controller 10 and the detection circuit 12 can be configured by combining a microprocessor or a microcomputer, an electronic component such as a semiconductor, an electric resistor, and a capacitor, and a program for operating the microprocessor. In addition, the faucet controller 10 and the detection circuit 12 can be integrally configured by the electronic components described above.

Next, the configuration of the detection circuit 12 will be described with reference to FIG.
As shown in FIG. 2, the detection circuit 12 includes a microcomputer 16, a drive circuit 18, a signal conversion circuit 20, and a voltage dividing circuit 22.
The microcomputer 16 is configured to function as a contact determination circuit 16a, a contact determination confirmation circuit 16b, an abnormality detection circuit 16c, and a frequency adjustment circuit 16d by a program for operating the microcomputer 16. The operation of these circuits will be described later. Further, the microcomputer 16 is configured to control two transistors constituting the drive circuit 18 by output signals from the two output ports P1 and P2. Further, the microcomputer 16 includes an A / D conversion circuit that converts an analog voltage signal output from the signal conversion circuit 20 into a digital value. Each circuit built in the microcomputer 16 performs a calculation based on the converted digital value, and determines whether or not the detection unit 2a is touched.

  The drive circuit 18 includes a PNP transistor 18a connected to the power supply side, an NPN transistor 18b connected to the ground side, and two electric resistors 18c and 18d. The emitter terminal of the PNP transistor 18a is connected to the power source, and the base terminal is connected to the output port P1 of the microcomputer 16. The electric resistance 18c is connected between the base and emitter of the PNP transistor 18a. On the other hand, the emitter terminal of the NPN transistor 18b is connected to the ground, and the base terminal is connected to the output port P2 of the microcomputer 16. The electric resistor 18d is connected between the base and emitter of the NPN transistor 18b. Further, the collector terminals of the PNP transistor 18a and the NPN transistor 18b are connected to each other, and are connected to one electrode (input terminal) of the piezoelectric element 4 via the signal line 4a. The other electrode of the piezoelectric element 4 is connected to the ground via the signal line 4b.

  The PNP transistor 18a and the NPN transistor 18b are alternately turned on and off in a predetermined cycle by signals from the output ports P1 and P2 of the microcomputer 16. When the PNP transistor 18a is on and the NPN transistor 18b is off, a voltage equal to the power supply voltage is output to the signal line 4a. On the other hand, when the PNP transistor 18a is off and the NPN transistor 18b is on, the signal line is output. 4a becomes the ground potential. By alternately repeating these states at a predetermined cycle, an AC voltage having a predetermined frequency is applied to one electrode of the piezoelectric element 4 via the signal line 4a. In the state where no AC voltage is applied to the piezoelectric element 4, both transistors are turned off, and the collectors of the transistors are set in a high impedance state (substantially electrically disconnected). . In the present embodiment, an alternating voltage is applied to the piezoelectric element 4 by alternately turning on and off the PNP transistor and the NPN transistor, but the alternating voltage is applied using an arbitrary switching element such as an FET. Can be applied.

  The voltage dividing circuit 22 includes two electric resistors 22a and 22b, and is configured to divide a voltage appearing at one terminal of the piezoelectric element 4 and adjust the voltage to an appropriate voltage. That is, one terminal of the electric resistor 22a is connected to the signal line 4a, and the other terminal is connected to one terminal of the electric resistor 22b. The other terminal of the electrical resistor 22b is connected to ground. As a result, the voltage appearing on the signal line 4a is divided by the resistance ratio of the electric resistors 22a and 22b and adjusted to an appropriate voltage. As described above, in a state where an AC voltage is applied to the piezoelectric element 4, the power supply voltage and the ground potential appear alternately at a predetermined cycle at one terminal (signal line 4 a) of the piezoelectric element 4. On the other hand, in the state where the output of the drive circuit 18 is set to high impedance (both transistors are off), the electromotive force generated by the piezoelectric element 4 appears on the signal line 4a. The voltage dividing circuit 22 divides these voltages and outputs the divided voltages to the signal conversion circuit 20. That is, the terminal connected to one electrode of the piezoelectric element 4 functions as an input terminal for applying an AC voltage, and the output signal of the piezoelectric element 4 is acquired from this input terminal.

  The signal conversion circuit 20 includes two capacitors 20a and 20b, a diode 20c, and an electric resistance 20d. One terminal of the capacitor 20a is connected to the connection point of the electric resistors 22a and 22b of the voltage dividing circuit 22, and the other terminal is connected to the anode terminal of the diode 20c. Further, the cathode terminal of the diode 20 c is connected to the input terminal of an A / D converter built in the microcomputer 16. The cathode terminal of the diode 20c is connected to the ground via a capacitor 20b and an electric resistance 20d. As a result, the output signal from the voltage dividing circuit 22 has its DC component removed by the capacitor 20a, the signal from which the DC component has been removed is detected by the diode 20c, and the high frequency component is cut by the capacitor 20b. To the A / D converter.

Next, the configuration of the detection unit 2a will be described with reference to FIGS.
As shown in FIG. 3, the detection unit 2 a is configured by a metal member attached to the tip of the faucet body 2, and forms the appearance of the faucet device 1 together with the faucet body 2. The detection unit 2a has a disk part that is touched by the user's fingers and the like, and a cylindrical part that extends from the disk part to the back side, and the piezoelectric element 4 is mounted in the cylindrical part on the back side of the disk part. ing.

  In this embodiment, the piezoelectric element 4 is a disk-shaped element using piezoelectric ceramics such as barium titanate or lead zirconate titanate, and electrodes are provided on both sides of the piezoelectric ceramic. By applying an AC voltage between these electrodes via the signal lines 4a and 4b, the piezoelectric element 4 repeatedly deforms and bends as a whole. In addition, since the piezoelectric element 4 is fixed to the back side of the disk part of the detection unit 2a with an adhesive, the piezoelectric element 4 and the disk part integrally bend and vibrate. That is, by applying an alternating voltage of a predetermined frequency to the piezoelectric element 4, the detection unit 2a flexurally vibrates with an amplitude of about several μm. Conversely, when the piezoelectric element 4 is bent and vibrated, an electromotive force is generated between the electrodes (between the signal lines 4a and 4b). In the present embodiment, the frequency of the applied AC voltage is set to about 40 kHz, which is a resonance frequency when the piezoelectric element 4 and the disk portion are bent and vibrated together. Preferably, the resonance frequency is set to an ultrasonic band of about 20 kHz to about 60 kHz.

Next, the detection principle of the touch detection device according to the first embodiment of the present invention will be described with reference to FIGS.
FIG. 4 shows a typical output waveform of the piezoelectric element 4 when the user does not touch the detection unit 2a in the touch detection device according to the first embodiment of the present invention, and FIG. 5 shows the detection unit by the user. A typical output waveform of the piezoelectric element 4 when touching 2a is shown. 4 and FIG. 5, in the upper stage, output voltage waveforms from the output ports P1 and P2 (FIG. 2) of the microcomputer 16, and in the middle stage, the output voltage waveform of the piezoelectric element 4 (voltage waveform between the signal lines 4a and 4b). The lower stage shows the output voltage waveform (A / D converter input waveform of the microcomputer 16) from the signal conversion circuit 20 circuit. 4 and 5 and the like schematically show signal waveforms, which are different from actual waveforms such as the number of waves output during application of an AC voltage.

  First, application of an alternating voltage to the piezoelectric element 4 is started at time t1 in FIG. That is, as shown in the upper part of FIG. 4, by alternately outputting voltage pulses to the output ports P1 and P2 of the microcomputer 16, the PNP transistor 18a and the NPN transistor 18b of the drive circuit 18 (FIG. 2) are alternately turned on. Turned on. Thereby, as shown in the middle part of FIG. 4, a pulsed AC voltage is applied between both electrodes of the piezoelectric element 4 (between the signal lines 4a and 4b). By applying this AC voltage, the piezoelectric element 4 is flexibly vibrated. As described above, the frequency of the alternating voltage applied to the piezoelectric element 4 is set so as to coincide with the resonance frequency of the detection unit 2 a and the piezoelectric element 4 that vibrate in an integrated manner. For this reason, the amplitude of the bending vibration of the detection unit 2a and the piezoelectric element 4 due to the application of the AC voltage is about several μm, and the amplitude is larger than when the vibration is excited at other frequencies. During application of the AC voltage, the terminal (signal line 4a) of the piezoelectric element 4 is connected to either the power supply voltage or the ground by the PNP transistor 18a or the NPN transistor 18b. The inter-voltage (middle stage in FIG. 4) is dominated by these (the electromotive force generated by the bending vibration of the piezoelectric element 4 does not appear).

  Next, at time t2 in FIG. 4, the application of the alternating voltage to the piezoelectric element 4 is stopped. When the application of the AC voltage is stopped, both the PNP transistor 18a and the NPN transistor 18b of the drive circuit 18 are turned off, and the output of the drive circuit 18 becomes high impedance (electrically disconnected). On the other hand, the detection unit 2a and the piezoelectric element 4 are flexibly vibrated at a resonance frequency by excitation of vibration between times t1 and t2, and this vibration remains even after the application of the AC voltage is stopped at time t2 (general). This phenomenon is referred to as “reverberation”) and gradually attenuates (the vibration amplitude decreases). In addition, since the output of the drive circuit 18 is set to high impedance after the application of the AC voltage is stopped, it is generated by bending vibration of the piezoelectric element 4 between both terminals of the piezoelectric element 4 (between the signal lines 4a and 4b). The generated electromotive force appears (time t2 in the middle of FIG. 4).

The touch detection device according to the first embodiment of the present invention applies the detection unit 2a to the detection unit 2a based on the magnitude of “reverberation vibration” remaining in the detection unit 2a (and the piezoelectric element 4) after the application of the AC voltage is stopped. The presence or absence of a touch operation is determined.
Here, as shown in the middle of FIG. 4, when the touch operation on the detection unit 2a is not performed, the voltage amplitude is large after time t2 when the application of the AC voltage is stopped, and the vibration is attenuated. The time will be longer. On the other hand, as shown in the middle part of FIG. 5, when a touch operation is performed on the detection unit 2a (a user's finger or the like is in contact with the detection unit 2a), the voltage amplitude after time t2 is The vibration is small and damped in a short time. That is, when the user's finger or the like is in contact with the detection unit 2a, the vibration of the detection unit 2a is absorbed by the contacted finger or the like, and the “reverberation vibration” that remains after the application of the AC voltage is stopped is reduced. It is considered a thing.

  In the present embodiment, the DC component of the voltage waveform of the piezoelectric element 4 shown in the middle stage of FIGS. 4 and 5 is removed, and touching is performed based on the detected output waveform of the signal conversion circuit 20 (lower stage of FIGS. 4 and 5). Whether or not there is. Specifically, in the present embodiment, the area surrounded by the output waveform of the signal conversion circuit 20 after time t2 (the area of the hatched portion in the lower stage of FIGS. 4 and 5; the detection unit 2a and the piezoelectric element after excitation stop) 4 is proportional to the vibration energy of 4).

Next, with reference to FIG. 6 thru | or FIG. 15, the effect | action of the faucet device 1 by 1st Embodiment of this invention is demonstrated.
FIG. 6 is a main flow showing the operation of the faucet device 1 of the present embodiment, and FIG. 7 is a time chart showing an example of the operation. FIG. 8 is a touch detection flow called as a subroutine from the main flow of FIG. The time chart of FIG. 7 is similar to the time charts of FIGS. 4 and 5, the output voltage waveform from the output ports P 1 and P 2 at the first stage, the output voltage waveform of the piezoelectric element 4 at the second stage, and the third stage. The output voltage waveform from the signal conversion circuit 20 circuit is shown in the eye, and the determination output output from the detection circuit 12 to the faucet controller 10 is shown in the lowest stage.

The processing in the flowchart of FIG. 6 is executed by the microcomputer 16 and the program built in the detection circuit 12.
First, in step S1, the frequency adjustment of the AC voltage applied to the piezoelectric element 4 is executed. This frequency adjustment is a process for accurately matching the frequency of the AC voltage applied to the piezoelectric element 4 with the resonance frequency of the detection unit 2a and the piezoelectric element 4, and this process is detected in the present embodiment. Executed when the circuit 12 is powered on. As a modification, the present invention can be configured such that a frequency adjustment execution switch (not shown) is provided in the detection circuit 12 and the frequency adjustment is executed by operating this switch.

  In order for the touch detection device of the present embodiment to exhibit its performance sufficiently, it is necessary to make the frequency of the AC voltage to be applied and the resonance frequency sufficiently match. There is an individual difference in the resonance frequency at which the detection unit 2a and the piezoelectric element 4 vibrate greatly, and the frequency of the alternating voltage applied depending on the faucet body 2 (the detection unit 2a and the piezoelectric element 4) combined with the detection circuit 12 It is desirable to adjust. In addition, by providing such a frequency adjustment function, it is possible to deal with individual variations of the faucet body 2 combined with the detection circuit 12 and to be able to be combined with a plurality of types of faucet bodies 2. The detection circuit 12 can be configured. Specific processing in step S1 will be described later.

Next, in step S2 of FIG. 6, the 10 ms timer is reset. In the present embodiment, application of an alternating voltage to the piezoelectric element 4 is executed intermittently every 10 ms that is a sensing cycle. In step S2, the 10 ms timer that controls the application interval of the AC voltage is reset, and the integration of the timer is started. Preferably, the sensing period is set to about 10 to 100 ms.
Further, in step S3, a touch detection flow shown in FIG. 8 is executed as a subroutine. The touch detection executed in step S3 is executed based on the principle described with reference to FIGS. 4 and 5, and specific processing in the flow of FIG. 8 will be described later. In the example shown in FIG. 7, step S <b> 3 is executed at time t <b> 10, and an AC voltage is applied to the piezoelectric element 4.

  Next, in step S4, it is determined whether the detection result in step S3 is “touch” or “non-touch”. If it is “touch”, the process proceeds to step S5, and if it is “non-touch”, the process proceeds to step S11. In the example illustrated in FIG. 7, since the reverberation after excitation (application of AC voltage) performed between times t10 and t11 is large, it is determined as “non-touch”. In step S11 after being determined as “non-touch”, the process waits until the timer whose integration is started in step S2 reaches 10 ms, and returns to step S2 when 10 ms elapses.

  In step S2, the 10 ms timer is reset and integration is started again. In step S3, touch detection is performed again. In the example shown in FIG. 7, step S3 is executed again at time t12, 10 ms after the previous excitation start at time t10. Furthermore, in the example of FIG. 7, since the reverberation after the excitation stop (starting from time t13) started at time t12 is small, the detection result in step S3 is determined to be “touch”. If it is determined as “touch” in step S3, the process proceeds from step S4 to step S5.

  In step S5, it is determined whether or not the detection result in step S3 has changed from “non-touch” to “touch”. In the example of FIG. 7, since the previous detection result started at time t10 is “non-touch” and the current detection result started at time t12 is “touch”, the process proceeds to step S6.

  In step S6, the flowchart shown in FIG. 8 which is “touch confirmation detection” is executed as a subroutine. This “touch confirmation detection” is a process executed when the detection result in step S3 changes from “non-touch” to “touch” in order to prevent erroneous detection due to “touch detection” in step S3. Specifically, “touch confirmation detection” is performed by applying an AC voltage to the piezoelectric element 4 for a longer period than “touch detection”, and specific processing will be described later. In the example of FIG. 7, “touch confirmation detection” is started at time t14 immediately after “touch detection” in step S3 is completed.

  In step S7, it is determined whether or not the result of “touch confirmation detection” is “touch”. If it is “non-touch”, there is a high possibility that the detection of “touch” in step S3 is a false detection, so the process proceeds to step S11 without opening and closing the solenoid valve, and 10 ms elapses from time t12. Wait until On the other hand, if the result of “touch confirmation detection” is “touch”, the determination of “touch” is confirmed, and the process proceeds to step S8.

  In step S8, it is determined whether or not the faucet device 1 is in a water discharge state. If it is in the water discharge state, the process proceeds to step S10, and if it is not in the water discharge state, the process proceeds to step S9. In step S10, since the detection unit 2a is newly touched in the water discharge state (time t12), the hot water electromagnetic valve 8a and the water electromagnetic valve 8b are closed and switched to the water stop state. Specifically, when detection of “touch” is confirmed in the detection circuit 12, a signal indicating “touch confirmation” is output from the detection circuit 12 to the faucet controller 10, and the faucet controller 10 transmits the hot water solenoid valve 8 a. And a control signal is sent to the electromagnetic valve 8b for water, and these are closed. On the other hand, in step S9, since the detection unit 2a is newly touched in the water stop state (time t12), the hot water electromagnetic valve 8a and the water electromagnetic valve 8b are opened and switched to the water discharge state. In the example shown in FIG. 7, the detection of “touch” is confirmed by the touch confirmation detection in step S6 started at time t14, and a determination output indicating that the detection of “touch” is confirmed at time t15 is a faucet. It is output to the controller 10.

  As described above, even when “touch” to the detection unit 2a is detected, the touch detection in step S3 is performed at regular intervals every 10 ms which is a predetermined sensing cycle. That is, in the example shown in FIG. 7, step S3 is executed at time t16, 10 ms after time t12. Even in the touch detection executed at time t16, the reverberation is still small and the detection unit 2a remains touched. Therefore, the processing in the flow of FIG. 6 is executed in the order of steps S3 → S4 → S5 → S12. .

In step S12, the duration of the “touched” state is measured. Specifically, the elapsed time after the determination of “touch” is confirmed at time t15 in FIG. 7 is measured.
Next, in step S13, it is determined whether or not the touch duration measured in step S12 has exceeded 1 minute. If it does not exceed 1 minute, the process proceeds to step S11, and while the user is touching the detection unit 2a, the process of steps S11 → S2 → S3 → S4 → S5 → S12 → S13 → S11 is repeated. . On the other hand, when it exceeds 1 minute, it progresses to step S13-> S10, and the solenoid valve 8a for hot water and the solenoid valve 8b for water are closed regardless of the state of the faucet device 1. That is, it is an abnormal operation that the user has touched the detection unit 2a for more than 1 minute, and there is a high possibility of erroneous touch detection or failure. For this reason, regardless of the state of the faucet device 1, the hot water solenoid valve 8a and the water solenoid valve 8b are closed to prevent waste of water.

  Furthermore, when “non-touch” is detected in the touch detection of step S3 executed at time t17 in FIG. 7, it is recognized that the user has released his / her finger from the detection unit 2a, and the determination output from the detection circuit 12 is detected. Is changed to “non-touch” (time t18). However, the state of the faucet device 1 continues at the time t15 in FIG. 7 (the water discharge state or the water stop state). After time t18, until the detection unit 2a is touched again by the user, the process of steps S3 → S4 → S11 → S2 → S3 is repeated in the flow of FIG.

  Thereafter, when the user touches the detection unit 2a again and this touch is confirmed, in the flow of FIG. 6, processing is performed in the order of steps S3 → S4 → S5 → S6 → S7 → S8. The state of the device 1 is switched (returns to the state before time t15 in FIG. 7). Thus, in the faucet device 1 of this embodiment, every time the user touches the detection unit 2a (operation from when the user touches the detection unit 2a until it is released), the water discharge state and the water stop state alternate. Can be switched.

Next, details of the touch detection executed in step S3 of FIG. 6 will be described with reference to FIGS. 4, 5, and 8. FIG.
In the touch detection flow shown in FIG. 8, first, an AC voltage is applied to the piezoelectric element 4 for 1 ms to excite the detection unit 2a. Next, whether or not the user is touching the detection unit 2a is determined based on the magnitude of reverberation for 1 ms after the application of the AC voltage is stopped. The touch detection flow shown in FIG. 8 is executed by the microcomputer 16 and the contact determination circuit 16a and the abnormality detection circuit 16c configured by a program.

First, in step S21 in FIG. 8, application of an alternating voltage to the piezoelectric element 4 is started (time t1 in FIGS. 4 and 5). Next, in step S22, the value of the variable n is set to 1. Further, in steps S23 to S27, during the application of the AC voltage, the output voltage of the signal conversion circuit 20 (FIG. 2) (lower stage in FIGS. 4 and 5) is sampled four times every 250 μs and A / D converted. Thus, four output voltage values AD ₂₁ , AD ₂₂ , AD ₂₃ , AD ₂₄ (lower stage in FIGS. 4 and 5) from the signal conversion circuit 20 are acquired in the 1 ms excitation period.

Next, in step S28, the outputs of the ports P1 and P2 of the microcomputer 16 (FIG. 2) are set to Hi and Lo, respectively, whereby both the PNP transistor 18a and the NPN transistor 18b are turned off (AC voltage output). End, time t2 in FIG. 4 and FIG. In step S29, the value of the variable n is set to 1. Further, in steps S30 to S34, immediately after the application of the AC voltage is stopped, the output voltage of the signal conversion circuit 20 is sampled four times every 250 μs and A / D converted. Thus, four output voltage values AD ₁₁ , AD ₁₂ , AD ₁₃ , AD ₁₄ (lower stage in FIGS. 4 and 5) from the signal conversion circuit 20 are acquired in the reverberation period of 1 ms after the excitation is stopped.

Next, in step S35, the output voltage value AD ₁₁ acquired in step S30 to S34, AD _12, AD _13, and the sum SUM1 the AD ₁₄ is calculated. The value of SUM1 has a strong correlation with the area of the shaded portion in FIGS. 4 and 5 and is an amount representing the reverberation energy of the vibration of the detection unit 2a.
Further, in step S36, the average value SUM1 _AV of the values of the respective SUM1 calculated when the flowchart of FIG. 8 is executed in the last three minutes is calculated. That is, SUM1 _AV is a moving average value of SUM1 for the past 3 minutes. Here, since the time during which the user touches the detection unit 2a in one operation is about 1 s at most, most of the SUM1 values calculated in the past 3 minutes are “non-touch”. It can be said that it was acquired in the state. Therefore, SUM1 _AV , which is the average of SUM1, represents the average magnitude of reverberation energy in the “non-touch” state.

Then, in step S37, the value of SUM1 and SUM1 _AV is compared. If SUM1 is larger than ½ of SUM1 _AV, the process proceeds to step S38. That is, when SUM1 is larger than ½ of SUM1 _AV , the reverberation energy SUM1 detected this time does not differ greatly from the average reverberation energy SUM1 _AV in the case of “non-touch”, so step S38. Is determined as “non-touch”, and the one-time process of the flowchart of FIG. 8 is terminated. This “non-touch” determination is used for the determination in step S4 of the main flow (FIG. 6).

On the other hand, if SUM1 is less than or equal to 1/2 of SUM1 _AV , the process proceeds to step S39. That is, when SUM1 is less than or equal to ½ of SUM1 _AV , the reverberation energy SUM1 detected this time is significantly lower than the average reverberation energy SUM1 _AV in the case of “non-touch”. Therefore, there is a high possibility that a touch operation is performed on the detection unit 2a. That is, in the present embodiment, based on the vibration energy of the detection unit 2a after the application of the AC voltage is stopped, it is determined whether or not “touch” to the detection unit 2a has been performed, and the vibration energy is equal to or less than a predetermined threshold value. In this case, it is determined that “touch” has been performed.

In step S39, the maximum value and the minimum value are extracted from the four output voltage values AD ₂₁ , AD ₂₂ , AD ₂₃ , and AD ₂₄ acquired during application of the AC voltage.
Further, in step S40, it is determined whether or not a value obtained by subtracting the minimum value from the maximum value extracted in step S39 is larger than a predetermined threshold value. When the value obtained by subtracting the minimum value from the maximum value is equal to or smaller than the predetermined threshold value, the process proceeds to step S41, where “touch” is determined in step S41, and one process of the flowchart of FIG. This “touch” determination is used for the determination in step S4 of the main flow (FIG. 6).

  On the other hand, if the value obtained by subtracting the minimum value from the maximum value extracted in step S39 is larger than the predetermined threshold value, the process proceeds to step S38. In step S38, it is determined as “non-touch”, and the flowchart of FIG. End one process. That is, the abnormality detection circuit 16c built in the microcomputer 16 detects an abnormality when the output voltage value fluctuates by a predetermined value or more during application of the AC voltage to the piezoelectric element 4, and determines “touch”. Do not do. As described above, when it is determined in step S37 that the reverberation energy SUM1 detected this time is significantly reduced, the difference between the maximum value and the minimum value is larger than the predetermined value in step S40. The reason for determining “non-touch” will be described below.

  FIG. 9 is a diagram illustrating an example of an output waveform when the resonance frequency of the detection unit 2a is slightly shifted from the frequency of the applied AC voltage. In addition, FIG. 9 is a waveform in the state in which the detection part 2a is not touched.

  As described above, the touch detection apparatus according to the first embodiment of the present invention applies an AC voltage having a frequency that matches the resonance frequency of the detection unit 2 a and the piezoelectric element 4 that are integrated and vibrates to the piezoelectric element 4, thereby alternating current. The presence or absence of a touch operation is determined based on the reverberation vibration after the voltage application is completed. However, in the touch detection device used for the water-surrounding apparatus as in this embodiment, water droplets often adhere to the detection unit. In this way, when the water droplets adhere, the resonance frequency of the detection unit 2a and the piezoelectric element 4 slightly decreases due to the mass of the adhered water droplets, which may adversely affect the determination reliability. It was found.

  As described above, when the resonance frequency of the detection unit 2a and the piezoelectric element 4 changes, the resonance frequency and the frequency of the AC voltage applied to the piezoelectric element 4 are slightly shifted, and a so-called “beat” phenomenon occurs. Has been found by the present inventors. Such a change in resonance frequency may also occur when the temperature of the detection unit 2a changes due to the influence of hot water or cold water on the detection unit 2a. FIG. 9 is an example of an output waveform when a “beat” phenomenon occurs due to a frequency shift. In this case, the output waveform of the piezoelectric element 4 during application of an AC voltage is different from that of FIGS. 4 and 5. It will be different.

  The above phenomenon will be described. When the detection unit 2a and the piezoelectric element 4 are in bending vibration, an electromotive force is generated between the electrodes (between the signal lines 4a and 4b) due to the deformation of the piezoelectric element 4. This is the same even when an AC voltage is applied to the input terminal (signal line 4a) with respect to the piezoelectric element 4. However, when the resonance frequency of the detection unit 2a and the piezoelectric element 4 matches the frequency of the applied AC voltage, the PNP occurs at the timing when a negative electromotive force is generated at the input terminal (signal line 4a) of the piezoelectric element 4. The transistor 18a is turned on, and the NPN transistor 18b is turned on at a timing when a positive electromotive force is generated. That is, the ideal excitation state is a relationship in which the applied voltage of the AC voltage and the electromotive force of the piezoelectric element are in opposite phases. At this time, since the impedance when the PNP transistor 18a and the NPN transistor 18b are on is smaller than the impedance of the piezoelectric element 4, the input terminal (signal line 4a) of the piezoelectric element 4 is set to either the power supply voltage or the ground. The waveform appears to be in a connected state.

  In the output waveform shown in FIG. 9, the voltage waveform during application of the AC voltage instantaneously exceeds the power supply voltage at the rising edge of the pulse. Similarly, when the pulse falls, the value is instantaneously equal to or lower than the ground potential. This is a phenomenon that occurs because the resonance frequency of the detection unit 2a and the piezoelectric element 4 and the applied frequency of the AC voltage do not coincide slightly. When an AC voltage is applied to the detection unit 2a and the piezoelectric element 4, bending vibration is generated at a specific resonance frequency. The waveforms in FIGS. 4 and 5 described above are obtained when an AC voltage is applied in a completely opposite phase to the electromotive force due to the bending vibration. However, for example, when water drops adhere to the detection unit 2a and the resonance frequency slightly decreases, the frequency of the ports P1 and P2 output from the microcomputer 16 (FIG. 2) is constant, so the AC voltage is higher than the resonance frequency. Will be applied. Then, when the piezoelectric element 4 still generates a positive electromotive force, the PNP transistor 18a is turned on to apply a positive voltage, and when the NPN transistor 18b still generates a negative electromotive force, There is a timing shift from the original reverse phase to the same phase, which is turned on and a negative voltage is applied.

  For example, when the PNP transistor 18a is turned on and the signal line 4a rises to a potential close to the power supply voltage and a positive voltage is further applied to the signal line 4a by the electromotive force of the piezoelectric element 4, the power supply voltage is applied to the collector of the PNP transistor 18a. Exceeding voltage will be applied. More specifically, the current due to the positive electromotive force of the piezoelectric element 4 flows from the collector of the PNP transistor 18a to the base (a PN junction is used during this period, so that it becomes a forward diode), and further flows to the power supply side through the electric resistor 18c. . Therefore, the PNP transistor 18a does not function as a transistor switch, and a waveform exceeding the power supply voltage appears on the signal line 4a as shown in FIG. The relationship between the negative electromotive voltage and the NPN transistor 18b is a similar phenomenon in which the polarity is reversed. Also, when the resonance frequency of the piezoelectric element 4 is high (generally, this tendency is at a low temperature), it is necessary to consider the timing shift in the opposite way, but it is the same as when the resonance frequency is low. The phenomenon occurs.

  Thus, when there is a difference between the resonance frequency and the frequency of the applied AC voltage, a phenomenon occurs in which the pulse waveform during application of the AC voltage is disturbed and the amplitude changes. In order to prevent a “touch” from being detected in such a state where there is a deviation in frequency and preventing false detection, in step S40 of FIG. 8, the difference between the maximum value and the minimum value during application of the AC voltage is predetermined. If the threshold value is exceeded, it is determined as “non-touch”.

  Further, in the output waveform shown in FIG. 9, the disturbance of the waveform appearing at the falling portion of the pulse waveform is gradually increased. The main cause of this phenomenon is considered to be that the difference in timing between the electromotive force of the piezoelectric element 4 and the applied AC voltage gradually increases due to the difference between the resonance frequency of the piezoelectric element 4 and the applied frequency of the AC voltage. In addition, it is considered that one of the reasons is that the vibration amplitude of the piezoelectric element 4 gradually increases and the generated electromotive force increases after excitation is started by application of an AC voltage. Further, in the output waveform shown in FIG. 9, the reverberation vibration after the application of the AC voltage is stopped is smaller than that in FIG. 4 even though the detection unit 2a is not touched. This is because the vibration amplitude of the piezoelectric element 4 is not sufficiently large because the resonance frequency of the detection unit 2a and the piezoelectric element 4 is shifted from the frequency of the AC voltage that excites it. Therefore, if the determination of “touch” or “non-touch” is made based on the reverberation vibration in a state where the resonance frequency and the frequency of the AC voltage are shifted, there is a possibility that erroneous detection occurs.

The “touch confirmation detection” process executed in step S6 of FIG. 6 is a process provided to prevent such erroneous detection.
Next, details of touch confirmation detection will be described with reference to FIGS. 10 and 11. This “touch confirmation detection” process is executed as a contact determination confirmation operation after the user's “touch” is once determined. Note that the touch confirmation detection flow shown in FIG. 10 is executed by the microcomputer 16 and a contact determination confirmation circuit 16b configured by a program.
FIG. 10 is a flowchart showing the “touch confirmation detection” process called as a subroutine in step S6 of FIG. FIG. 11 is a diagram illustrating an example of an output waveform when touch confirmation detection is performed in a state where the resonance frequency of the detection unit 2a is slightly shifted from the frequency of the applied AC voltage. In addition, FIG. 11 is a waveform in the state in which the detection part 2a is not touched.

Here, the flowchart of the touch confirmation detection shown in FIG. 10 is the same as the flowchart of the touch detection shown in FIG. 8 except for steps S127 and S139. That is, in the “touch detection” shown in FIG. 8, an AC voltage is applied for 1 ms, and during this period, four output voltage values AD _{21 to} AD ₂₄ are acquired every 250 μs, whereas FIG. In “touch confirmation detection”, an AC voltage is applied for 2 ms as a predetermined confirmation period, and eight output voltage values AD _{21 to} AD ₂₈ are acquired every 250 μs during this period. Accordingly, in step S139, the maximum value and the minimum value is extracted from among the eight output voltage value AD ₂₁ to AD _28, in step S140, these differences are compared with a threshold value.

As shown in FIG. 11, the output waveform obtained by such touch confirmation detection has an extended AC voltage application time as a confirmation period, and therefore, the amplitude of the pulse waveform is disturbed during application of the AC voltage ( Change). Further, in the output waveform of FIG. 11, the amplitude exceeding the power supply voltage of the pulse waveform once increases and then decreases. This is because the frequency at which the detection unit 2a and the piezoelectric element 4 vibrate and the frequency of the alternating voltage to be applied are shifted, the phase relationship between the two vibrations changes with time, It is considered that the amplitude of the pulse waveform increases when the polarities of the outputs of the drive circuit 18 match, that is, when the phases are the same (near AD _{25 in the} lower part of FIG. 11). When the application of the AC voltage is continued, the timing of the same phase described above returns to the timing of the opposite phase that is the original application timing of the AC voltage as time passes (near AD _{28 in the} lower stage of FIG. 11). This is the reason why a phenomenon such as “beat” occurs in the waveform. For this reason, by setting the AC voltage application time longer, it is possible to reliably detect an increase in the amplitude of the pulse waveform during application of the AC voltage (during the confirmation period), and as a result, detect a slight shift in the resonance frequency. This makes it possible to prevent erroneous determination.
The time for applying the AC voltage is doubled to 1 ms in FIG. 8 and 2 ms in FIG. However, in this embodiment, when an AC voltage is applied at the resonance frequency of the detection unit 2a and the piezoelectric element 4, 1 ms is set as a sufficient time to reach a stable bending vibration state. Therefore, even if the application of the AC voltage is continued for 1 ms or more, the amplitude of the bending vibration does not increase further. Therefore, the reverberation vibration determination process after the application of the AC voltage is completed may be the same process in FIGS.

  In the present embodiment, when no water droplets or the like are attached to the detection unit 2a, the detection unit 2a can be vibrated with sufficient vibration amplitude by excitation of 1 ms by the “touch detection” process. Can be detected. For this reason, as described with reference to FIG. 7, the “touch detection” process is performed every 10 ms that is the sensing cycle in the normal time, and when it is determined as “touch” by this process (time t12 to t14 in FIG. 7). The “touch confirmation detection” process (time t14 to t15 in FIG. 7) is executed to confirm the “touch” determination and prevent erroneous detection. As a result, the time for exciting the detection unit 2a can be minimized, the power required for excitation can be saved, and the service life of the piezoelectric element 4 can be extended.

  Further, when a user's finger touches the detection unit 2a in a state where water droplets or the like are attached to the detection unit 2a, the detection unit 2a (and the piezoelectric element 4 during application of an AC voltage to the piezoelectric element 4). ) Is suppressed, the electromotive force generated by the piezoelectric element 4 is also reduced. For this reason, in the state where a finger or the like is in contact with the detection unit 2a, even when the resonance frequency of the detection unit 2a and the piezoelectric element 4 and the frequency of the AC voltage to be applied are deviated, Is not disturbed (the amplitude of the pulse waveform changes greatly and does not become a waveform as shown in FIG. 9 or FIG. 11). Accordingly, when the pulse waveform is disturbed during application of the AC voltage, even if it is determined as “non-touch” (step S40 in FIG. 8 and step S140 in FIG. 10), if the user performs a touch operation, This can be reliably detected.

Next, automatic adjustment of the frequency of the AC voltage applied to the piezoelectric element 4 will be described with reference to FIGS.
FIG. 12 is a flowchart showing the “frequency adjustment” process called as a subroutine in step S1 of FIG. This “frequency adjustment” process is executed by the microcomputer 16 and a frequency adjustment circuit 16d configured by a program. FIGS. 13 to 15 are diagrams showing the relationship between the resonance frequency of the detector 2a and the frequency shift of the applied AC voltage and the output waveform. FIG. 13 is an example of an output waveform when the resonance frequency of the detection unit 2a and the frequency of the applied AC voltage are relatively large. FIG. 14 is an example of an output waveform when the resonance frequency of the detection unit 2a and the frequency of the applied AC voltage are slightly shifted. FIG. 15 is an example of an output waveform when the resonance frequency of the detection unit 2a and the frequency of the AC voltage to be applied are sufficiently matched.

  As described above, the resonance frequency of the detection unit 2 a and the piezoelectric element 4 that vibrate integrally needs to be sufficiently coincident with the frequency of the AC voltage applied to the piezoelectric element 4. However, there are individual differences between the detection unit 2a and the piezoelectric element 4, and the resonance frequency varies to some extent. For this reason, it is desirable to adjust the frequency of the alternating voltage output from the detection circuit 12 (FIG. 2) according to the resonance frequency of the detection unit 2a and the piezoelectric element 4 that are connected to the detection circuit 12 and used. The detection circuit 12 built in the touch detection device of this embodiment has a function of automatically adjusting the frequency of the AC voltage to be applied in accordance with the resonance frequency of the connected detection unit 2 a and the piezoelectric element 4. By providing this function, it is possible to cope with variations in the detection unit 2a and the piezoelectric element 4, and also to change the resonance frequency due to aging, and to replace the detection unit 2a and the piezoelectric element 4 after product shipment. Can respond. Furthermore, it is also possible to configure a general-purpose detection circuit that can be freely combined and used for a plurality of types of detection units and piezoelectric elements having different basic designs such as shapes and dimensions and having different resonance frequencies.

FIG. 12 is a flowchart showing the “frequency adjustment” process. In this “frequency adjustment” process, first, an AC voltage is applied to the piezoelectric element 4 for 2 ms, and eight output voltage values AD _{21 to} AD ₂₈ are acquired every 250 μs during this period (steps S202 to S209 in FIG. 12). Then, four output voltage values AD _{11 to} AD ₁₄ in reverberation vibration for 1 ms after application stop are obtained every 250 μs (steps S 210 to S 214). Furthermore, the difference between the maximum value and the minimum value AD _2PP among the output voltage values AD _{21 to} AD ₂₈ thus obtained, and the total value of the output voltage values AD _{11 to} AD ₁₄ are the applied AC voltage. Are stored together with the frequency (steps S216 to S218). Such application of AC voltage and acquisition of output voltage values are executed for a plurality of frequencies (steps S201, S219, and S220), and the frequency closest to the resonance frequency is the “touch detection” process and “touch”. It is set as the frequency of the alternating voltage applied in “confirmation detection” (step S221).

Specifically, the frequency of the AC voltage is changed by 0.5% within a range of ± 10% with respect to the standard frequency Fr, which is a design value of the resonance frequency of the detection unit 2a and the piezoelectric element 4, and the frequency for each frequency is changed. The output voltage value (the difference between the maximum value and the minimum value AD _2PP and the total value of AD _{11 to} AD ₁₄ ) is stored.

FIG. 13 to FIG. 15 are examples of output waveforms obtained in this way.
First, when the resonance frequency of the detection unit 2a and the piezoelectric element 4 and the frequency of the applied AC voltage are relatively large, as shown in FIG. 13, the reverberation vibration after the application of the AC voltage is stopped is very small. Become. In such a case, the total value of the output voltage values AD _{11 to} AD ₁₄ becomes very small. Further, the amplitude of the pulse waveform during application of the AC voltage is also constant (the difference AD _2PP between the maximum value and the minimum value of the output voltage values AD _{21 to} AD ₂₈ is substantially zero). This is because the piezoelectric element 4 is not excited to a very large amplitude even when an AC voltage is applied because the resonance frequency and the frequency of the applied AC voltage are relatively large.

Next, as shown in FIG. 14, when the resonant frequency and the frequency of the applied AC voltage are slightly shifted, the piezoelectric element 4 is excited to a relatively large amplitude by the application of the AC voltage. For this reason, the reverberation vibration after the application of the AC voltage is stopped is relatively large, and the total value of the output voltage values AD _{11 to} AD ₁₄ is also relatively large. On the other hand, since the vibration of the piezoelectric element 4 during application of the AC voltage and the phase of the pulse waveform of the AC voltage are slightly shifted, a part of the output voltage value (near AD ₂₅ ) during application of the AC voltage is increased. As a result, the difference AD _2PP between the maximum value and the minimum value of the output voltage values AD _{21 to} AD ₂₈ increases.

Furthermore, as shown in FIG. 15, when the resonance frequency and the frequency of the applied AC voltage sufficiently match, the piezoelectric element 4 is greatly excited by the application of the AC voltage. The reverberation vibration at is maximized, and the total value of the output voltage values AD _{11 to} AD ₁₄ is also maximized. On the other hand, the phase relationship between the vibration of the piezoelectric element 4 during application of the AC voltage and the pulse waveform of the AC voltage is constant, and the amplitude of the pulse waveform does not exceed the width of the power supply voltage during application of the AC voltage. Thereby, the difference AD _2PP between the maximum value and the minimum value of the output voltage values AD _{21 to} AD ₂₈ becomes small.

In step S221 of the flowchart of FIG. 12, the resonance frequency of the detection unit 2a and the piezoelectric element 4 is obtained using the above-described properties. Specifically, first, the frequency at which the reverberation vibration (the total value of the output voltage values AD _{11 to} AD ₁₄ ) is maximized is selected as the resonance frequency. Next, when there are a plurality of frequencies at which the reverberation vibration is maximum, the frequency at which the difference AD _2PP between the maximum value and the minimum value is the smallest is selected as the resonance frequency. When there are a plurality of frequencies having the same reverberation vibration and the difference AD _2PP between the maximum value and the minimum value, the lowest frequency is selected as the resonance frequency. This is because when the resonance frequency at which the electrical impedance of the piezoelectric element 4 is minimized and the anti-resonance frequency at which it is maximized are close to each other, the resonance frequency appears on the low frequency side.

  According to the touch detection device of the first embodiment of the present invention, based on the vibration of the detection unit 2a after the application of the AC voltage is stopped (time t2 in FIGS. 4 and 5), the user's fingers and the like Since the contact with the detection unit 2a is determined, the vibration of the detection unit 2a is also changed by a light “touch” to the detection unit 2a, so that the “touch” can be reliably detected. In addition, since the piezoelectric element 4 is attached to the detection unit 2a to excite vibrations, the circuit is unstable even when the piezoelectric element 4 is disposed at a location away from the drive circuit 18 or the contact determination circuit 16a. Will not malfunction. Thereby, it becomes possible to arrange | position the detection circuit 12 freely and it becomes possible to comprise the water implement with high design property.

  Moreover, according to the touch detection apparatus of this embodiment, since the vibration excitation element is comprised by the piezoelectric element 4, a vibration excitation element can be comprised with a simple structure. Further, since the contact determination circuit 16a determines contact of the user's finger or the like with the detection unit 2a based on the output signal from the piezoelectric element 4, an element or device for detecting the vibration of the detection unit 2a is provided. Without providing separately, the vibration of the detection unit 2a can be detected, and the configuration of the touch detection device can be simplified.

  Furthermore, according to the touch detection device of the present embodiment, since the output signal is acquired from the signal line 4a that applies the AC voltage to the piezoelectric element 4, the wiring that applies the AC voltage and the wiring that acquires the output signal At least a part of them can be shared, and the wiring of signal lines can be simplified. Further, since the output of the drive circuit 18 becomes high impedance after the application of the AC voltage is stopped (time t2 in FIGS. 4 and 5), even when the impedance of the output signal from the piezoelectric element 4 is high An accurate output signal can be obtained.

  In addition, according to the touch detection device of the present embodiment, the contact determination circuit 16a can detect the vibration energy of the detection unit 2a after the application of the AC voltage is stopped (time t2 in FIGS. 4 and 5) (see FIGS. 4 and 5). Since the touch is detected based on the area of the hatched portion (SUM1 in FIG. 8) (step S37 in FIG. 8), the slight vibration attenuation due to the touch of a finger or the like can be surely captured, and a highly sensitive touch detection device Can be configured.

Furthermore, according to the touch detection device of the present embodiment, the abnormality detection circuit 16c outputs the output signal (the output voltage value AD _{21 in} FIG. 8) during application of the AC voltage to the piezoelectric element 4 (time t1 to t2 in FIG. 9). ˜AD ₂₄ ) to detect an abnormality (steps S39 and S40 in FIG. 8), it is possible to detect an abnormality without complicating the touch detection process, and to suppress the occurrence of erroneous detection. Can do.

Further, according to the touch detection device according to this embodiment, the abnormality detection circuit 16c during application of the AC voltage amplitude variations of the output signal at (time t1~t2 in FIG. 9) (the output voltage value AD ₂₁ to AD ₂₄ Since abnormality is detected based on (maximum value−minimum value) (steps S39 and S40 in FIG. 8), it is possible to reliably detect the occurrence of abnormality and to prevent malfunction due to erroneous detection.

  Furthermore, according to the touch detection device of the present embodiment, the contact determination confirmation circuit 16b is configured to perform a contact determination confirmation operation (steps S3 and S4 in FIG. 6) after the contact determination circuit 16a once determines contact with a finger or the like (steps S3 and S4 in FIG. 6). Since step S6 in FIG. 6 and FIG. 10) are executed, erroneous detection can be prevented more reliably. Further, the contact determination confirmation operation is executed after the contact determination circuit 16a once determines the contact of the object, so that the contact determination confirmation operation is prevented from being performed in a situation where there is no possibility of erroneous detection ( Steps S4 → S11 and steps S5 → S12 in FIG. 6 can be performed.

  Further, according to the touch detection device of the present embodiment, in the contact determination confirmation operation (step S6 in FIG. 6), an AC voltage is applied to the piezoelectric element 4 for a predetermined confirmation period (time t1 to t2 in FIG. 11) longer than normal. Since it is applied, an abnormality during application of the AC voltage can be detected more reliably.

  Furthermore, according to the touch detection device of the present embodiment, the frequency adjustment circuit 16d adjusts the frequency of the applied AC voltage to a frequency at which the detection unit 2a to which the piezoelectric element 4 is attached resonates (FIG. 15). Thus, since the detection unit 2a is excited at the resonance frequency, the detection unit 2a can be vibrated with a large amplitude by a small excitation force, and the touch detection device can be operated with less energy consumption.

  Further, according to the touch detection device of the present embodiment, the frequency adjustment circuit 16d executes the application of the AC voltage for a predetermined time (times t1 to t2 in FIGS. 13 to 15) at a plurality of different frequencies, so that the AC voltage The frequency at which the amplitude of the output signal from the piezoelectric element 4 after the application is stopped (time t2 in FIGS. 13 to 15) is determined as the frequency at which the detection unit 2a attached with the piezoelectric element 4 resonates (FIG. 12). Step S221). As a result, the frequency of the AC voltage can be adjusted even after the detection unit 2a and the piezoelectric element 4 are assembled to the water tool, so that the frequency of the AC voltage to be applied is resonated even when the resonance frequency is shifted due to secular change. Can be adjusted to the frequency.

  Furthermore, according to the touch detection device of the present embodiment, the frequency adjustment circuit 16d has a plurality of frequencies at which the amplitude of the output signal becomes maximum after the application of the AC voltage is stopped (time t2 in FIGS. 13 to 15). In this case, the frequency at which the fluctuation of the amplitude of the output signal during application of the AC voltage to the piezoelectric element 4 is the smallest among the frequencies having the maximum amplitude is the frequency at which the detection unit 2a attached with the piezoelectric element 4 resonates. (Step S221 in FIG. 12). For this reason, the resonant frequency of the detection part 2a to which the piezoelectric element 4 is attached can be set automatically and reliably with a simple algorithm.

Next, a faucet device according to a second embodiment of the present invention will be described with reference to FIGS.
The faucet device according to the present embodiment includes only the “touch detection” process and the “touch confirmation detection” process that are called as subroutines from steps S3 and S6 of the main flow in FIG. This is different from the first embodiment. Accordingly, here, only the points of the second embodiment of the present invention that are different from the first embodiment will be described, and description of similar parts will be omitted.

  FIG. 16 is a touch detection flow called as a subroutine from the main flow of FIG. 6 in the second embodiment of the present invention. FIG. 17 is a diagram illustrating a typical output waveform of the piezoelectric element when the user does not touch the detection unit in the touch detection device according to the second embodiment of the present invention. FIG. 18 is a diagram illustrating a typical output waveform of the piezoelectric element when the user touches the detection unit in the touch detection device according to the second embodiment of the present invention. FIG. 19 is a diagram illustrating an example of an output waveform when the resonance frequency of the detection unit is slightly shifted from the frequency of the applied AC voltage. FIG. 20 is a touch confirmation detection flow called as a subroutine from the main flow of FIG. 6 in the second embodiment of the present invention. FIG. 21 is a diagram illustrating an example of an output waveform when touch confirmation detection is performed in a state where the resonance frequency of the detection unit is slightly shifted from the frequency of the applied AC voltage.

In the touch detection device of this embodiment, the flowchart of FIG. 16 is executed as a subroutine for performing the “touch detection” process.
First, in step S301, application of an alternating voltage to the piezoelectric element 4 is started. Next, in step S302, it is determined whether the detection output (output from the signal conversion circuit 20) is equal to or greater than a predetermined “frequency deviation threshold”, and this process continues until 1 ms elapses from the start of application of the AC voltage. Repeated (steps S303 and S305). If the detection output is equal to or higher than the “frequency shift threshold” during application of the AC voltage, the process proceeds to step S304, and it is stored that the threshold has been exceeded.

  As shown in the lower part of FIGS. 17 and 18, the “frequency deviation threshold” is a value slightly larger than the normal detection output when the resonance frequency of the detection unit 2 a matches the frequency of the applied AC voltage. Is set to That is, as described in the first embodiment, when the resonance frequency of the detection unit 2a and the frequency of the alternating voltage to be applied sufficiently coincide with each other, the pulse waveform during application of the alternating voltage (during excitation) is reduced. The amplitude is almost the same as the power supply voltage (middle stage in FIGS. 17 and 18), and the signal conversion circuit 20 outputs the detected pulse waveform. On the other hand, as shown in the middle part of FIG. 19, when the resonance frequency of the detection unit 2a deviates from the frequency of the applied AC voltage due to the attachment of water droplets or the like to the detection unit 2a, a pulse during application of the AC voltage is applied. The amplitude of the waveform is larger than that in the normal state, and a portion exceeding the width of the power supply voltage appears. Thereby, as shown in the lower part of FIG. 19, the output from the signal conversion circuit 20 exceeds the “frequency shift threshold”.

  Next, in step S306, it is determined whether or not the detection output (output from the signal conversion circuit 20) has decreased below a predetermined “reverberation threshold” after the application of the AC voltage is stopped. This process is repeated until 500 μs elapses after the application of AC voltage is stopped (step S307). As shown in the lower part of FIGS. 17 to 19, in this embodiment, the “reverberation threshold” is set to about 50% of the normal detection output.

  If the detection output falls below the “reverberation threshold” before 500 μs elapses after the application of the AC voltage is stopped, the process proceeds to step S308. If not, the process proceeds to step S310. In step S310, it is determined that the user's finger or the like has not touched the detection unit 2a, that is, “non-touch”. In the case of “non-touch”, the reverberation vibration after the application of the AC voltage is stopped is large, and a relatively large vibration remains even after 500 μs has elapsed after the stop. .

  On the other hand, in step S308, it is determined whether the detection output is equal to or higher than the “frequency deviation threshold” during application of the AC voltage. If the detection output is equal to or higher than the “frequency deviation threshold”, the process proceeds to step S310. , “Non-touch” is determined. This is because, when the resonance frequency of the detection unit 2a deviates from the frequency of the AC voltage to be applied, the reverberation vibration is small even in the case of “non-touch”, and the reverberation vibration is quickly reduced below the “reverberation threshold”. Therefore, erroneous detection is prevented by determining “non-touch”. As described in the first embodiment, when the user is “touching”, the detection output is equal to or higher than the “frequency deviation threshold” even if a water droplet or the like is attached to the detection unit 2a. Therefore, even if water droplets or the like are attached, it can be determined as “touch”.

  If the detection output is not equal to or higher than the “frequency deviation threshold” during the application of the AC voltage, the process proceeds from step S308 to S309, and the user's finger or the like touches the detection unit 2a. It is determined as “touch”. This is because, when the user is “touching”, the reverberation vibration is small, and the reverberation vibration quickly falls below the “reverberation threshold”. As described above, when the vibration amplitude after the elapse of a predetermined time after the application of the alternating voltage is attenuated to a predetermined amplitude or less, it is determined as “touch”.

Next, with reference to FIG. 20 and FIG. 21, touch confirmation detection in the second embodiment of the present invention will be described.
FIG. 20 is a flowchart showing the “touch confirmation detection” process called as a subroutine in step S6 of FIG. FIG. 21 is a diagram illustrating an example of an output waveform when touch confirmation detection is performed in a state where the resonance frequency of the detection unit 2a is slightly shifted from the frequency of the applied AC voltage. FIG. 21 shows a waveform when the detection unit 2a is not touched.

  Here, the flowchart of the touch confirmation detection shown in FIG. 20 is the same as the flowchart of the touch detection shown in FIG. 16 except that step S323 is different from step S303 of FIG. That is, in the “touch detection” process shown in FIG. 16, an AC voltage is applied for 1 ms, whereas in the “touch confirmation detection” process shown in FIG. 20, an AC voltage is applied for 2 ms. The

  As shown in FIG. 21, when the AC voltage is applied for 2 ms, the disturbance of the pulse waveform during the application of the AC voltage can be detected more accurately. ”Can be accurately determined. In this way, by increasing the application time of the AC voltage, it is possible to reliably detect the difference between the resonance frequency of the detection unit 2a and the frequency of the applied AC voltage, and prevent erroneous detection. .

  In the second embodiment described above, whether or not the detection output (output from the signal conversion circuit 20) is reduced to a predetermined “reverberation threshold” or less after the AC voltage application is stopped is 500 μs or less. , “Touch”, “non-touch”. Therefore, as in the first embodiment, using a microcomputer, the output value from the signal conversion circuit 20 is not subjected to integration calculation (a process of summing up a plurality of A / D converted values), “Touch” and “Non-touch” can be determined. For example, in the second embodiment, determination is performed using a timer that measures the time after the application of AC voltage is stopped and a comparator that detects whether or not the detection output has dropped below the “reverberation threshold”. be able to. That is, “touch” or “non-touch” can be determined by measuring the time until the comparator detects a decrease to the “reverberation threshold” with a timer. Thereby, the detection circuit can be simplified.

  Furthermore, in the second embodiment described above, the determination is made based on the time until the detection output drops below a predetermined “reverberation threshold”. However, as a modified example, after the application of the AC voltage is stopped, the determination is performed for a predetermined time. The detection output at the time when the measurement has passed is measured, and “touch” or “non-touch” can be determined depending on whether the detection output is equal to or less than a predetermined threshold value. That is, it is determined as “touch” when the vibration amplitude after the elapse of a predetermined time after the application of the AC voltage is attenuated to a predetermined amplitude or less. This modification can also be determined by a comparator and a timer, and can be determined by a simple circuit.

Next, a faucet device according to a third embodiment of the present invention will be described with reference to FIGS. 22 to 32C.
The faucet device of this embodiment is different from the first embodiment described above only in the configuration and operation of the detection circuit. Accordingly, here, only the points of the third embodiment of the present invention that are different from the first embodiment will be described, and description of similar parts will be omitted.

  The first and second embodiments of the present invention described above are touch detection devices used for a watering device, and the piezoelectric element 4 attached to the detection unit 2a has an alternating current with a frequency that matches the resonance frequency of the detection unit 2a. A voltage is intermittently applied, and contact of a user's finger or the like with the detection unit 2a is detected based on the reverberation vibration (FIG. 4) of the detection unit 2a after the application is stopped. That is, the “touch” to the detection unit 2a is determined based on the characteristic that the reverberation vibration decreases when the user's finger or the like touches the detection unit 2a (FIG. 5).

In the first and second embodiments of the present invention described above, when the amplitude of the output signal from the piezoelectric element 4 during application of the alternating voltage increases (FIG. 9), the resonance frequency of the detection unit 2a changes with temperature. It is determined that there is a deviation from the frequency of the AC voltage applied to the piezoelectric element 4 due to factors such as the adhesion of water droplets and water droplets, and it is not determined as “touch” even if the reverberation decreases. .
Further, the magnitude of the reverberation is measured by changing the frequency of the AC voltage to be applied, and the frequency at which this becomes the maximum is estimated as the resonance frequency of the detection unit 2a, and the frequency of the AC voltage is automatically adjusted (FIG. 12). ).

  By automatically adjusting the frequency of the AC voltage to be applied, variations, fluctuations, etc. of the detection unit 2a and the detection circuit 12 can be absorbed, and the frequency of the AC voltage can be matched with the resonance frequency. However, the automatic frequency adjustment may not be able to be performed accurately depending on the environment in which the adjustment is performed. If automatic adjustment of the frequency is performed before the faucet device is shipped from the factory, the adjustment environment can be adjusted to a certain condition, so that accurate adjustment can be performed. However, in consideration of a change over time in the resonance frequency of the detection unit 2a, a case where the detection unit 2a is replaced in the event of a failure, etc., it is desirable that automatic adjustment is possible even at the actual use site of the faucet device.

  In this way, when performing automatic frequency adjustment at the site of use, the user touches the detection unit during automatic adjustment, water droplets or the like are attached to the detection unit 2a, and the detection unit 2a touches hot water or ice. In some cases, it is difficult to make accurate adjustments such as extremely high or low temperatures. It is also conceivable that electrical noise may accidentally occur during automatic adjustment and errors may be mixed into the adjustment result.

  The change in resonance frequency due to the attachment of water droplets or the like, or extremely high or low temperatures is temporary, and the resonance frequency can be reduced by dropping or evaporating water droplets or returning the temperature of the detection unit 2a to room temperature. Returns to its normal value. Accordingly, the appropriate countermeasure is different depending on the cause of the deviation between the frequency of the applied AC voltage and the resonance frequency. If the frequency of the AC voltage is changed by frequently performing automatic adjustment with respect to a temporary change in the resonance frequency, the operation of the touch detection device may be unstable. In addition, if automatic adjustment is frequently performed, touch detection cannot be performed during that time, and the usability of the touch detection device is deteriorated.

Furthermore, water droplets or the like frequently adhere to the detection unit 2a of the watering device. For this reason, it is desirable to prevent erroneous detection of “touch” without waiting for execution of automatic adjustment when there is a difference between the frequency of the applied AC voltage and the resonance frequency of the detection unit.
The water faucet device according to the third embodiment of the present invention aims to solve these problems.

FIG. 22 is a circuit diagram showing a schematic configuration of the detection circuit in the present embodiment.
As shown in FIG. 22, the detection circuit 12 in this embodiment includes a microcomputer 16, a drive circuit 18, a signal conversion circuit 20, and a voltage dividing circuit 22.
The drive circuit 18 in the present embodiment is different from the first embodiment in that the output (the connection point between the collectors of the PNP transistor 18a and the NPN transistor 18b) is connected to the signal line 4a via the coupling capacitor 18e. . Thereby, even when there is an offset in the voltage output of the drive circuit 18, only the AC voltage component is applied to the signal line 4a.
In addition, the microcomputer 16 according to the present embodiment determines whether the frequency deviation detection circuit 16e and the resonance frequency detection are successful in addition to the contact determination circuit 16a, the contact determination confirmation circuit 16b, the abnormality detection circuit 16c, and the frequency adjustment circuit 16d. The difference from the first embodiment is that a circuit 16f is incorporated. These frequency deviation detection circuit 16e and determination circuit 16f are also realized by a program for operating the microcomputer 16.

Next, the operation of the faucet device according to the third embodiment of the present invention will be described with reference to FIGS. 23 to 32C.
FIG. 23 is a main flow showing the operation of the faucet device of the present embodiment.
The process in the flowchart of FIG. 23 is executed by the microcomputer 16 and the program built in the detection circuit 12.

  First, in step S401 of FIG. 23, frequency adjustment of the AC voltage applied to the piezoelectric element 4 is executed. This frequency adjustment is a process for accurately matching the frequency of the AC voltage applied to the piezoelectric element 4 with the resonance frequency of the detection unit 2a and the piezoelectric element 4, and this process is detected in the present embodiment. Executed when the circuit 12 is powered on. In step S401, the flowchart shown in FIG. 26 is called as a subroutine. Specific processing in the flowchart of FIG. 26 will be described later.

Next, in step S402 in FIG. 23, the 10 ms timer is reset. In the present embodiment, application of an alternating voltage to the piezoelectric element 4 is executed intermittently every 10 ms that is a sensing cycle. In step S402, the 10 ms timer that controls the application interval of the AC voltage is reset, and the integration of the timer is started.
Further, in step S403, a touch on the detection unit 2a by the user is detected. That is, it is determined whether or not the user has touched the detection unit 2a based on the vibration of the detection unit 2a after the AC voltage of a predetermined frequency is applied to the piezoelectric element and the application of the AC voltage is stopped. Specifically, in step S403, the flowchart shown in FIG. 24 is called as a subroutine. Specific processing in the flowchart of FIG. 24 will be described later.

Next, in step S404, it is determined whether or not a predetermined timing for confirming the coincidence with the resonance frequency has arrived. That is, it is confirmed at predetermined time intervals whether or not the frequency of the AC voltage applied to the piezoelectric element matches the resonance frequency of the detector 2a. In the present embodiment, it is desirable that the frequency of the alternating voltage applied to the piezoelectric element and the resonance frequency of the detector 2a match. The frequency deviation detection circuit 16e realized by the microcomputer 16 checks whether or not the frequency of the AC voltage and the resonance frequency sufficiently match each minute during the operation of the detection circuit 12. If it is time to confirm the coincidence of frequencies, the process proceeds to step S405, where it is confirmed whether or not they coincide, and if not, the process proceeds to step S406 without performing confirmation.
In step S405, the flowchart shown in FIG. 27 is called as a subroutine. Specific processing in the flowchart of FIG. 27 will be described later.

  In step S406, in the confirmation in step S405, it is determined whether or not the frequency of the AC voltage and the resonance frequency match. If they match, the process proceeds to step S407, and if they deviate, the process proceeds to step S419. move on. If it is determined in step S404 that it is not the time to confirm the coincidence with the resonance frequency and the process proceeds from step S404 to S407, the determination in step S406 is based on the confirmation result in step S405 executed in the latest past. Done. Accordingly, once the deviation between the frequency of the AC voltage and the resonance frequency is confirmed in step S405, the process shifts from step S406 to step S419 for at least one minute thereafter.

  Next, in step S419, integration of the duration of the frequency shift after it is determined in step S406 that “frequency shift has occurred” is started. This integration is continuously performed until it is determined in step S406 that “frequency shift has not occurred” and the integration of the duration time is reset in step S407.

Next, in step S420, it is determined whether or not the duration of the accumulated frequency deviation is n minutes (n is an integer). If it is n minutes, the process proceeds to step S421, and if it is not n minutes, the process proceeds to step S418. In step S418, the process waits until the timer whose integration is started in step S402 reaches 10 ms. When 10 ms elapses, the process returns to step S402, and the processes in and after step S402 are repeated.
On the other hand, when the duration of the accumulated frequency deviation is n minutes, the process proceeds to step S421, and in step S421, the frequency readjustment flow shown in FIG. 29 is executed as a subroutine. Therefore, the frequency readjustment flow in step S421 is executed every minute while the frequency deviation continues. Specific processing in the flowchart of FIG. 29 will be described later.

  On the other hand, if the frequency of the AC voltage matches the resonance frequency, the process proceeds to step S407, and in step S407, the accumulated time duration of the frequency deviation is reset. As described above, in the processing after step S419, the time during which the state in which the frequency of the AC voltage applied to the piezoelectric element is shifted from the resonance frequency of the detection unit 2a continues is integrated. In step S407, since it is determined in step S406 that the frequency is not off, the duration of the accumulated frequency deviation is reset.

  Next, in step S408, it is determined whether the detection result in step S403 is “touch” or “non-touch”. If it is “touch”, the process proceeds to step S409, and if it is “non-touch”, the process proceeds to step S418. In step S418 after it is determined as “non-touch”, the process waits until the timer whose integration is started in step S402 reaches 10 ms. When 10 ms elapses, the process returns to step S402, and the processes in and after step S402 are repeated.

  On the other hand, in step S408, when the detection result in step S403 is “touch”, the process proceeds to step S409, and in step S409, it is determined whether or not the previous state is “touch”. That is, in step S409, it is determined whether or not the “touch” determination has been confirmed when step S409 was executed last time. The state determined as “touch” in step S413 (described later) executed in the previous loop is called “determination of touch”. If it is determined in step S409 that the previous state is “touch (touch determination is confirmed)”, the process proceeds to step S422, and the previous state is “non-touch (touch determination is not determined)”. In that case, the process proceeds to step S410.

  Next, in step S410, it is determined whether or not the “temporary touch flag” is zero. Here, the “provisional touch flag” is a flag that is changed to “1” in a state where “touch” has not been “fixed” but is determined to be “touch” in the previously executed touch detection in step S403. It is. That is, when “temporary touch flag” = 0 at the time of execution of step S410, the process proceeds to step S411, and “temporary touch flag” is changed to 1 in step S411.

  After the “provisional touch flag” is changed to 1 in step S411, the process proceeds to step S418, and when the timer whose integration has started is 10 ms, the processes in and after step S402 are repeated. When step S410 is executed again in the state of “temporary touch flag” = 1, the process proceeds to touch confirmation detection in step S412. As described above, when the state detected in step S403 (touch detection) from the state of “non-touch” (“provisional touch flag” = 0) is determined to be “touch” twice in step S408, The process proceeds from step S410 to step S412 and touch confirmation detection is executed.

  In step S412, the flowchart shown in FIG. 25 which is “touch confirmation detection” is executed as a subroutine. This “touch confirmation detection” is executed when the detection result in step S403 changes from “non-touch” to “touch” twice in succession in order to prevent erroneous detection due to “touch detection” in step S403. It is processing. Specific processing in “touch confirmation detection” will be described later.

  In step S413, it is determined whether or not the result of “touch confirmation detection” is “touch”. If it is “non-touch”, it is highly likely that the detection of “touch” in step S403 was a false detection, so the process proceeds to step S418 without opening and closing the solenoid valve, and the processes in and after step S402 are performed. Is repeated. On the other hand, when the result of “touch confirmation detection” is “touch”, “touch determination is confirmed”, and the process proceeds to step S415.

  In step S415, it is determined whether or not the faucet device 1 is in a water discharge state. If it is in the water discharge state, the process proceeds to step S416, and if it is not in the water discharge state, the process proceeds to step S417. In step S417, since the detection unit 2a is newly touched in the water discharge state, the hot water solenoid valve 8a and the water solenoid valve 8b are closed and switched to the water stop state. On the other hand, in step S416, since the detection unit 2a is newly touched in the water stop state, the hot water solenoid valve 8a and the water solenoid valve 8b are opened and switched to the water discharge state.

  As described above, even when “determination of touch” is confirmed to the detection unit 2a, the touch detection in step S403 is executed at regular intervals every 10 ms which is a predetermined sensing cycle. If the user continues to “touch” the detection unit 2a in a state where “touch determination is confirmed”, the processing in the main flow of FIG. 23 is performed in steps S403 → S404 → S406 → S407 → S408 → S409. → Proceed as in S422 (provided that “frequency shift” has not occurred).

In step S422, the duration of the “touch” state is measured. Specifically, the elapsed time after “touch determination is confirmed” in step S413 is measured.
Next, in step S423, it is determined whether or not the touch duration measured in step S422 has exceeded 1 minute. If it does not exceed 1 minute, the process proceeds to step S418, and while the user is touching the detection unit 2a, steps S418 → S402 → S403 → S404 → S406 → S407 → S408 → S409 → S422 → S423 → The process of S418 is repeated (assuming that “frequency shift” has not occurred). On the other hand, when it exceeds 1 minute, it progresses to step S423-> S417, and the hot water solenoid valve 8a and the water solenoid valve 8b are closed regardless of the state of the faucet device 1. That is, it is an abnormal operation that the user has touched the detection unit 2a for more than 1 minute, and there is a high possibility of erroneous touch detection or failure. For this reason, regardless of the state of the faucet device 1, the hot water solenoid valve 8a and the water solenoid valve 8b are closed to prevent waste of water.

  Furthermore, when “non-touch” is detected in the touch detection in step S403, it is recognized that the user has released his / her finger from the detection unit 2a, and the determination output from the detection circuit 12 is changed to “non-touch”. The However, as for the state of the faucet device 1, the most recently switched state (water discharge state or water stop state) is continued. After the detection of “non-touch”, the process of steps S402 → S403 → S404 → S406 → S407 → S408 → S418 → S402 is repeated in the main flow of FIG. 23 until the detection unit 2a is touched again by the user. (However, it is assumed that there is no “frequency shift”).

  Thereafter, when the user touches the detection unit 2a again and this state is continued, in the main flow of FIG. 23, steps S402 → S403 → S404 → S406 → S407 → S408 → S409 → S410 → S411 → S418. The processes are performed in the order of S402 → S403 → S404 → S406 → S407 → S408 → S409 → S410 → S412 → S413 → S415 to “determine touch determination”, and the state of the faucet device 1 is switched. As described above, the faucet device 1 according to the present embodiment has a water discharge state and a water stoppage each time the user touches the detection unit 2a (operation from the state where the user releases the finger from the detection unit 2a to the touch). The state is switched alternately.

Next, details of the touch detection executed in step S403 in FIG. 23 will be described with reference to FIGS. 24, 30 and 31. FIG.
FIG. 24 is a touch detection flow called as a subroutine from the main flow, and FIG. 30 is a detection waveform data acquisition flow called as a subroutine from the touch detection flow. The touch detection flow shown in FIG. 24 is executed by the microcomputer 16 and a contact determination circuit 16a and an abnormality detection circuit 16c configured by a program.
FIG. 31 is a diagram illustrating an example of a detected waveform to be acquired. FIG. 31 shows the output voltage waveform from the output ports P1 and P2 (FIG. 22) of the microcomputer 16 in the upper stage, the output voltage waveform of the piezoelectric element 4 in the middle stage (voltage waveform between the signal lines 4a and 4b), and the lower stage. An output voltage waveform from the signal conversion circuit 20 (detection waveform: A / D converter input waveform of the microcomputer 16) is shown. FIG. 31 schematically shows the signal waveform, which differs from the actual waveform, such as the number of waves output during application of the AC voltage.

First, the touch detection flow shown in FIG. 24 is called as a subroutine from step S403 of FIG. 23 which is the main flow, and the detection waveform data acquisition flow shown in FIG. 30 is called as a subroutine from step S501 of this touch detection flow.
In detection waveform data acquisition flow shown in FIG. 30, first, by applying an AC voltage to the piezoelectric element 4 over the 0.8ms, to obtain the value AD ₂₁ to AD ₂₈ of the detected waveform by exciting the detecting unit 2a . Next, detection waveform values AD _{11 to} AD ₁₈ are acquired as the magnitude of reverberation for 0.8 ms after the application of the AC voltage is stopped.

In step S521 in FIG. 30, application of an alternating voltage to the piezoelectric element 4 is started (time t1 in FIG. 31). Next, in step S522, the value of the variable n is set to 1. Further, in steps S523 to S527, during application of the AC voltage, the output voltage (detection waveform: lower part of FIG. 31) of the signal conversion circuit 20 (FIG. 22) is sampled 8 times every 100 μs and A / D converted. Accordingly, eight output voltage values AD _{21 to} AD ₂₈ (lower part in FIG. 31) from the signal conversion circuit 20 are acquired in the excitation period of 0.8 ms.

Next, in step S528, the outputs of the ports P1 and P2 of the microcomputer 16 (FIG. 22) are set to Hi and Lo, respectively, whereby both the PNP transistor 18a and the NPN transistor 18b are turned off (AC voltage output). End, time t2 in FIG. In step S529, the value of the variable n is set to 1. Further, in steps S530 to S534, immediately after the application of the AC voltage is stopped, the output voltage of the signal conversion circuit 20 is sampled eight times every 100 μs and A / D converted. As a result, in the reverberation period of 0.8 ms after the excitation is stopped, eight output voltage values AD _{11 to} AD ₁₈ (lower part of FIG. 31) are acquired from the signal conversion circuit 20, and one process of the flowchart of FIG. Is completed, and the flow returns to the touch detection flow (step S501) shown in FIG.

Next, in step S502 of FIG. 24, the values obtained by subtracting the minimum value from the maximum value among the acquired output voltage value AD ₂₁ to AD ₂₈ is calculated in step S501, this value is set to AD _2PP. In the example shown in FIG. 31, since AD ₂₃ is the maximum and AD ₂₁ is the minimum, AD _2PP is calculated by AD ₂₃ -AD ₂₁ .
Further, in step S503, the difference between the data adjacent the output voltage value AD ₂₁ to AD ₂₈ acquired in step S501 is calculated, the maximum value of this difference is the AD _2DIF. In the example shown in FIG. 31, of the adjacent data, since the difference in D ₂₃ and AD ₂₂ are maximum, AD _2DIF is calculated by AD ₂₃ -AD _22.

Next, in step S504, the sum SUM1 output voltage value AD ₁₁ to AD ₁₈ acquired in step S501 is calculated. The value of SUM1 has a strong correlation with the area of the shaded portion in FIG. 31, and is an amount representing the reverberation energy of vibration of the detection unit 2a.
Further, in step S505, it is determined whether or not the output voltage values AD _{11 to} AD ₁₈ are monotonously decreasing. That is, it can be said that the decrease is monotonous if the later value is smaller than the previous value in the order of AD _{11 to} AD ₁₈ . In the example shown in FIG. 31, since AD ₁₄ increases with respect to AD ₁₃ , it is determined that the output voltage values AD _{11 to} AD ₁₈ are “not monotonously decreasing”.

Further, in step S506, the average value SUM1 _AV of the values of the respective SUM1 calculated when the flowchart of FIG. 24 is executed in the last three minutes is calculated. That is, SUM1 _AV is a moving average value of SUM1 for the past 3 minutes. Here, since the time during which the user touches the detection unit 2a in one operation is about 1 s at most, most of the SUM1 values calculated in the past 3 minutes are “non-touch”. It can be said that it was acquired in the state. Therefore, SUM1 _AV , which is the average of SUM1, represents the average magnitude of reverberation energy in the “non-touch” state.

Then, in step S507, the calculated AD _2DIF in step S503 is compared with a predetermined noise determination threshold, when AD _2DIF is smaller than the noise determination threshold value, the process proceeds to step S508, AD _2DIF is above the noise determination threshold value In the case, the process proceeds to S511. That is, when the detection circuit 12 picks up electrical noise, or when a hard object such as a knife hits the detection unit 2a, a pulsed disturbance occurs in the detection waveform. FIG. 31 shows an example in which the detection circuit 12 picks up noise, and the detection waveform is disturbed in the portion indicated as “noise” in the middle stage. When such a disturbance occurs, the detection waveform changes abruptly and the time differential value becomes large. Therefore, the maximum value AD _2DIF of the difference between adjacent detection values is compared with the noise determination threshold value, thereby detecting the wave. It can be determined whether or not the waveform is disturbed. In addition, by making a determination based on the maximum value AD _2DIF of the difference between adjacent detection values, the waveform is disturbed due to noise or the like, and the waveform generated when the frequency of the applied AC voltage and the resonance frequency of the detection unit 2a are deviated. Disturbances (FIGS. 9, 11, etc.) can be clearly distinguished.

  Next, in step S511 in FIG. 24, since the detected data has picked up noise or the like, the determination regarding touch detection is not performed from the current detection waveform, and “touch” or “touch” when this flowchart is executed last time. The determination of “non-touch” is maintained as it is, and one process of the flowchart shown in FIG. 24 is ended.

On the other hand, if AD _2DIF is smaller than the noise determination threshold value in step S507, the _process proceeds to step S508. In step S508, it is determined whether or not the values of AD _{11 to} AD ₁₈ representing reverberation are monotonously decreasing. If monotonically decreasing, the process proceeds to step S509. If not monotonously decreasing, step S511 is performed. Proceed to As described above, when the detection circuit 12 picks up noise or the like, the detection waveform is disturbed, and the values of AD _{11 to} AD ₁₈ do not monotonously decrease. In this case, since the detected data has picked up noise or the like, the process proceeds to step S511, and determination regarding touch detection is not performed from the current detection waveform.

On the other hand, in step S509, the value of SUM1 and SUM1 _AV is compared. SUM1 is the flow proceeds to step S510 in the case of 1/2 or less of SUM1 _AV, the process proceeds to step S514 is greater than half the SUM1 _AV. That is, when SUM1 is larger than ½ of SUM1 _AV , the reverberation energy SUM1 detected this time is not significantly different from the average reverberation energy SUM1 _AV in the case of “non-touch”, so step S514. Is determined as “non-touch”, and one-time processing of the flowchart of FIG. 24 is terminated. This “non-touch” determination is used for the determination in step S408 of the main flow (FIG. 23).

On the other hand, if SUM1 is less than or equal to 1/2 of SUM1 _AV , the process proceeds to step S510. That is, when SUM1 is less than or equal to ½ of SUM1 _AV , the reverberation energy SUM1 detected this time is significantly lower than the average reverberation energy SUM1 _AV in the case of “non-touch”. Therefore, there is a high possibility that a touch operation is performed on the detection unit 2a. That is, in the present embodiment, based on the vibration energy of the detection unit 2a after the application of the AC voltage is stopped, it is determined whether or not “touch” to the detection unit 2a has been performed, and the vibration energy is equal to or less than a predetermined threshold value. In this case, it is determined that “touch” has been performed.

In step S510, the difference AD _2PP between the maximum value and the minimum value of the output voltage values AD _{21 to} AD ₂₈ calculated in step S502 is compared with a predetermined deviation determination threshold value. When the difference AD _2PP between the maximum value and the minimum value is less than the predetermined deviation determination threshold value, the process proceeds to step S512, and in step S512, it is determined as “touch”, and one process of the flowchart of FIG. To do. This “touch” determination is used for the determination in step S408 of the main flow (FIG. 23).

On the other hand, if the difference AD _2PP between the maximum value and the minimum value is greater than or equal to a predetermined deviation determination threshold value in step S510, the process proceeds to step S513. As described above, when the reverberation energy is small and the detection output waveform during the excitation period is not a constant value, the AC applied to the piezoelectric element 4 in the first embodiment as described with reference to FIG. It is considered that the frequency of the voltage is shifted from the resonance frequency of the detection unit 2a. Therefore, it is determined as “frequency shift” in step S513, and then determined as “non-touch” in step S514, and the one-time process in the flowchart of FIG. 24 is terminated. That is, the abnormality detection circuit 16c built in the microcomputer 16 detects an abnormality when the output voltage value of the detection waveform fluctuates by more than a predetermined deviation determination threshold during application of the AC voltage to the piezoelectric element 4. , “Touch” is not judged.

  Thus, when there is a difference between the resonance frequency and the frequency of the applied AC voltage, a phenomenon occurs in which the pulse waveform during application of the AC voltage is disturbed and the amplitude changes. In order to prevent detection of “touch” in such a state where the frequency is shifted and erroneous detection, in step S510 of FIG. 24, the difference between the maximum value and the minimum value during application of the AC voltage is a predetermined value. When the deviation determination threshold is exceeded, it is determined as “non-touch”.

Next, with reference to FIG. 25 and FIGS. 32A to 32C, a touch confirmation detection flow for confirming the “touch” determination and “confirming the touch determination” will be described.
FIG. 25 shows a touch confirmation detection flow. This touch confirmation detection flow is called as a subroutine in step S412 of the main flow shown in FIG. FIG. 32A to FIG. 32C are time charts for explaining the determination of “touch” and the process of finalizing the determination of “touch”.

  First, in step S541 in FIG. 25, the frequency of the alternating voltage applied to the piezoelectric element 4 is set to a confirmation frequency that is 1% lower than the frequency applied in normal touch detection. In this embodiment, since the frequency of the alternating voltage applied in touch detection is about 40 kHz, the frequency of the alternating voltage is set to about 39.6 kHz in step S541. As described above, the contact determination confirmation circuit 16b determines that the touch by the user is once determined by the contact determination circuit 16a (step S410 in FIG. 23), and as a contact determination confirmation operation, what is the frequency of the normal AC voltage? An AC voltage having a different confirmation frequency is applied to the piezoelectric element 4.

  Next, in step S542, the above-described touch detection flow (FIG. 24) is called as a subroutine. The touch detection flow executed here is the same as the above-described process except that the frequency of the AC voltage applied to the piezoelectric element 4 is changed to about 39.6 kHz.

Furthermore, in step S543, the frequency of the AC voltage applied to the piezoelectric element 4 is set to a confirmation frequency that is 1% higher than the frequency of normal touch detection. For this reason, in step S543, the frequency of the AC voltage is set to about 40.4 kHz.
Next, in step S544, the above-described touch detection flow (FIG. 24) is called again as a subroutine. The touch detection flow executed here is the same as that in step S542 except that the frequency of the AC voltage applied to the piezoelectric element 4 is changed to about 40.4 kHz.

  Next, in step S545, the result of touch detection in steps S542 and S544 is determined. That is, if the return values from the touch detection flow executed as a subroutine in steps S542 and S544 are both “touch” determination (step S512 in FIG. 24), the process proceeds to step S546. If the determination is “non-touch” (step S514 in FIG. 24), the process proceeds to step S547.

  In step S546, it is determined that the user is actually touching the detection unit 2a, and the determination of “touch” is finalized (in the main flow of FIG. 23, the process proceeds from step S413 to S415). In this manner, the contact determination confirmation circuit 16b determines the “touch” to the detection unit 2a when the user's “touch” is determined by the contact determination circuit 16a even by the application of the alternating voltage of the confirmation frequency. Determine. On the other hand, in step S547, although “touch” is once determined (in step S403 of the main flow in FIG. 23), it is determined that the touch is not actually performed, and the determination of “non-touch” is confirmed. (In the main flow of FIG. 23, the process proceeds from step S413 to S418).

Next, the principle of touch confirmation detection will be described with reference to FIGS. 32A to 32C.
32A to 32C are time charts in which the horizontal axis indicates time, the upper level indicates the energy level of reverberation vibration caused by the application of each AC voltage, and the lower level indicates the presence or absence of “determination of touch determination”. is there.
FIG. 32A shows an example of a case where there is no shift in the resonance frequency of the detection unit 2a. First, before time t0 in FIG. 32A, the user is not “touching” the detection unit 2a, and applying an AC voltage to the piezoelectric element 4 causes a large reverberation vibration after the application. For this reason, before time t0, a reverberation vibration having a level higher than the threshold value indicated by the alternate long and short dash line in the upper part of FIG. 32A is detected every 10 msec.

  Next, when the user “touches” the detection unit 2a at time t0, the energy of the reverberation vibration detected in touch detection (step S403 in FIG. 23) executed at time t1 immediately after that decreases below the threshold value. To do. As described above, once “touch” is detected, the “temporary touch flag” is changed to 1 (step S411 in FIG. 23), and touch detection is performed again at time t2 (step S403 in FIG. 23). . If the energy of the reverberation vibration is low even in the touch detection executed at this time t2, touch confirmation detection (step S412 in FIG. 23) is executed.

  In the touch confirmation detection (subroutine of FIG. 25 called in step S412 of FIG. 23), first, at time t3, an AC voltage having a frequency lower than that of normal touch detection is applied to the piezoelectric element 4 (step S541 of FIG. 25). ). In a state where the user is “touching” the detection unit 2a, the energy of the reverberation vibration is reduced by reducing the frequency of the AC voltage even if a deviation occurs with respect to the frequency of the detection unit 2a. Subsequently, at time t4, an AC voltage having a frequency higher than that of normal touch detection is applied to the piezoelectric element 4 (step S543 in FIG. 25). Similarly, when the user is “touching” the detection unit 2a, the energy of the reverberation vibration is reduced even if the frequency of the AC voltage is increased. Thereby, “touch” is determined in the touch confirmation detection flow (FIG. 25) (steps S545 → S546 in FIG. 25). Thus, when “touch” is determined in the touch confirmation detection flow, determination of “touch” is confirmed in the main flow (FIG. 23) (steps S413 → S415 in FIG. 23, time t5 in FIG. 32A).

  After the determination of “touch” is confirmed at time t5 in FIG. 32A, until touch is detected as “non-touch” at time t6 (until the user releases his / her hand from the detection unit 2a), touch detection is performed every 10 msec (in FIG. 23). Step S403) is executed. During this time, the energy of the reverberation vibration detected is a value lower than the threshold value. When touch detection is executed at time t7 after time t6, the energy of the reverberation vibration detected is higher than the threshold value, and it is determined that the state is “non-touch” (time t8 in FIG. 32A). , Step S408 → S418 in FIG.

Next, with reference to FIG. 32B, the operation of touch confirmation detection when the resonance frequency of the detection unit 2a is increased due to a temperature change will be described.
In FIG. 32B, the “touch” by the user is not performed until time t13, but the energy of the reverberation vibration detected by touch detection (step S403 in FIG. 23) after time t0 due to the temperature change of the detection unit 2a. Tends to decrease. That is, the resonance frequency of the detection unit 2a is increased due to the temperature drop of the detection unit 2a, thereby causing a deviation from the frequency of the AC voltage applied in the touch detection. As a result, the energy of reverberation vibration that is detected without the detector 2a being sufficiently excited decreases.

  At time t1 in FIG. 32B, the energy of the reverberation vibration decreases due to the increase in the resonance frequency of the detection unit 2a, and the energy is lower than the threshold value even though it is not “touched”. As a result, the “touch” determination is erroneously made (steps S408 → S409 in FIG. 23), and if the “touch” determination is made at time t2 (steps S408 → S409 → S410 in FIG. 23), touch confirmation detection is performed. Is executed (steps S410 → S412 in FIG. 23, FIG. 25).

  In the touch confirmation detection, first, an AC voltage having a frequency lower than that of normal touch detection is applied to the piezoelectric element 4 (step S541 in FIG. 25, time t3 in FIG. 32B). At time t3, the user is not “touching” the detection unit 2a, but the resonance frequency of the detection unit 2a is increased, so that the difference between the frequency of the applied AC voltage and the resonance frequency is large and detected. This reduces the energy of reverberant vibration. Next, at time t4, an AC voltage having a frequency higher than that of normal touch detection is applied to the piezoelectric element 4 (step S543 in FIG. 25). Here, since the resonance frequency of the detection unit 2a is increased, the frequency of the applied AC voltage and the resonance frequency are approximate values, and the energy of the reverberation vibration detected is larger than the threshold value. Thereby, it is determined as “non-touch” in the touch confirmation detection (steps S545 → S547 in FIG. 25), and erroneous detection due to an increase in the resonance frequency is avoided.

  After time t4 in FIG. 32B, until the time t13, no “touch” is performed by the user. However, in the touch detection, the energy of the reverberation vibration is lower than the threshold because the resonance frequency of the detection unit 2a is increased. (Reverberation vibration energy at times t5 to t7 and t9 to t11). However, in the application of the AC voltage executed in the touch confirmation detection, a frequency higher than that of the normal AC voltage is applied, so that the energy of the reverberation vibration becomes larger than the threshold (the energy of the reverberation vibration at time t8 and t12). It is determined as “non-touch”. Thereby, erroneous detection due to an increase in the resonance frequency is avoided.

  Next, when the user “touches” at time t13 in FIG. 32B, the energy of the reverberation vibration due to the touch detection at time t14 and t15 is lowered. In addition, the energy of reverberation vibration due to touch confirmation detection at times t16 and t17 is also reduced. That is, when the user is “touching” the detection unit 2a, the energy of the reverberation vibration is lower than the threshold even in a state where the frequency of the applied AC voltage is close to the resonance frequency of the detection unit 2a (time t17). Thus, at time t18, “touch determination is confirmed”. As described above, in the touch confirmation detection, by applying an AC voltage having a higher frequency and a lower frequency than the normal touch detection to the piezoelectric element 4, it is possible to reliably detect “touch” while avoiding erroneous detection. .

  Touch detection is performed every 10 msec after “touch determination is confirmed” at time t18 in FIG. 32B until “non-touch” is reached at time t19 (until the user releases his / her hand from the detection unit 2a). The During this time, the energy of the reverberation vibration detected is a value lower than the threshold value. In the example shown in FIG. 32B, when touch detection is performed at time t20 after time t19, the temperature of the detection unit 2a is increased at this time, and the resonance frequency is close to the frequency of the AC voltage in normal touch detection. It has become. For this reason, the energy of the reverberation vibration detected by the touch detection at the time t20 becomes a value higher than the threshold value, and it is determined that the state is “non-touch” (time t21 to FIG. 32B).

  In the example shown in FIG. 32B, the case where the resonance frequency of the detection unit 2a is increased due to a temperature decrease has been described. However, the case where the resonance frequency of the detection unit 2a is decreased due to an increase in temperature of the detection unit 2a or adhesion of water droplets or the like. In this case, it is possible to reliably detect “touch” while avoiding erroneous detection by detecting touch confirmation. Note that when only a decrease in the resonance frequency is assumed due to the configuration and usage environment of the detection unit 2a, the present invention is configured to perform touch confirmation detection only at a frequency lower than the AC voltage in normal touch detection. You can also. Conversely, when only an increase in the resonance frequency of the detection unit 2a is assumed, the present invention can be configured to perform touch confirmation detection only at a frequency higher than the AC voltage in normal touch detection.

Next, with reference to FIG. 32C, the operation of touch confirmation detection when the resonance frequency of the detection unit 2 a is decreased due to a temperature rise will be described.
In FIG. 32C, although the “touch” by the user is not performed, the energy of the reverberation vibration detected by the touch detection tends to decrease after time t0 due to the temperature change of the detection unit 2a. In other words, the resonance frequency of the detection unit 2a is reduced due to the temperature rise of the detection unit 2a, thereby causing a deviation from the frequency of the AC voltage applied in the touch detection. As a result, the energy of the reverberation vibration that is detected without the excitation of the detector 2a sufficiently at the frequency of the AC voltage in the normal touch detection is reduced.

  For this reason, at times t1 and t2 in FIG. 32C, the energy of the reverberation vibration in the touch detection becomes lower than the threshold value and is determined as “touch” even though the user is not touching. By determining “touch”, the touch confirmation detection (step S412 in FIG. 23) is executed. In touch confirmation detection, an AC voltage having a frequency lower than that of normal touch detection is applied (step S541 in FIG. 25, time t3 in FIG. 32C), and then an AC voltage having a frequency higher than that in normal touch detection is applied. Applied (step S543 in FIG. 25, time t4 in FIG. 32C).

  Here, since the resonance frequency of the detection unit 2a is reduced due to the temperature rise, the AC voltage having a frequency lower than that of normal touch detection applied at time t3 in FIG. 32C is close to the resonance frequency of the detection unit 2a. Become. For this reason, in application of the alternating voltage at time t3, the energy of the reverberation vibration becomes larger than the threshold value. On the other hand, when an AC voltage having a frequency higher than that of normal touch detection, which is executed at time t4, is separated from the resonance frequency of the detection unit 2a, the energy of reverberation vibration is reduced. In the touch confirmation detection, since the energy of the reverberation vibration exceeds the threshold when the AC voltage is applied at time t3, it is determined as “non-touch” (steps S545 → S547 in FIG. 25), and erroneous detection is eliminated.

  Similarly, in the state where the temperature of the detection unit 2a is increased and the resonance frequency is decreased, reverberation vibration in normal touch detection (time t5, t6, t9, t10, t13, t14, t17, t18 in FIG. 32C). Energy is lower than the threshold. On the other hand, when a low-frequency AC voltage is applied in the touch confirmation detection (time t7, t11, t15, t19 in FIG. 32C), the energy of the reverberation vibration becomes larger than the threshold value, and erroneous detection is avoided. Furthermore, at time t21 in FIG. 32C, when the temperature of the detection unit 2a decreases and the resonance frequency returns to a normal value, the energy of the reverberation vibration in the normal touch detection becomes larger than the threshold value. It is determined as “non-touch” without being executed.

Next, the frequency initial adjustment will be described with reference to FIG.
FIG. 26 is a frequency initial adjustment flow executed by the frequency adjustment circuit 16d. The flowchart shown in FIG. 26 is called as a subroutine in step S401 of the main flow shown in FIG. The frequency adjustment circuit 16d searches the resonance frequency of the detection unit 2a within a predetermined frequency range as the first adjustment mode. That is, the frequency adjustment circuit 16d applies an AC voltage to the piezoelectric element 4 for a plurality of frequencies within a predetermined frequency range, acquires an output signal from the piezoelectric element 4 when the AC voltage is applied, Frequency adjustment is performed by analyzing the detection waveform of the output signal. In the first adjustment mode, the frequency of the alternating voltage applied to the piezoelectric element 4 in the touch detection is determined so as to coincide with the actual resonance frequency of the detection unit 2a.

  First, in step S601 in FIG. 26, the frequency of the alternating voltage applied to the piezoelectric element 4 is set to a value of 90% of the standard frequency Fr. The standard frequency Fr is a design value of the resonance frequency when the detection unit 2a and the piezoelectric element 4 vibrate together. In this embodiment, since the standard frequency Fr = 40 kHz, the frequency of the AC voltage is first set to 36 kHz. In the flowchart of FIG. 26, an AC voltage is applied to the piezoelectric element 4 at a plurality of frequencies between 90% and 110% of the standard frequency Fr, and the AC to be applied to the piezoelectric element 4 based on the energy of the reverberation vibration. The frequency of the voltage is determined. That is, in the first adjustment mode, the resonance frequency is searched for within the first frequency range including the standard frequency Fr.

Next, in step S602, the flowchart shown in FIG. 30 is executed as a subroutine. As described above, in the flowchart shown in FIG. 30, the AC voltage having the frequency set in step S601 is applied, and the output voltage values AD _{11 to} AD ₁₈ and AD _{21 to} AD _{28 of} the detected waveforms acquired at that time are applied. (FIG. 31) is acquired.

Next, in step S603 of FIG. 26, a value obtained by subtracting the minimum value from the maximum value of the output voltage values AD _{21 to} AD ₂₈ acquired in step S602 is calculated, and this value is set to AD _2PP . This value is stored along with the frequency of the applied AC voltage.
Further, in step S604, the difference between the data adjacent the output voltage value AD ₂₁ to AD ₂₈ acquired in step S602 is calculated, the maximum value of this difference is the AD _2DIF. This value is stored along with the frequency of the applied AC voltage.
Next, in step S605, the sum SUM1 output voltage value AD ₁₁ to AD ₁₈ acquired in step S602 is calculated. This value is stored along with the frequency of the applied AC voltage.
Furthermore, in step S606, it is determined whether or not the output voltage values AD _{11 to} AD ₁₈ are monotonously decreasing. It is memorize | stored with the frequency of the applied alternating voltage whether it is monotonously decreasing.

  Next, in step S607, the frequency of the AC voltage set in step S601 is increased by 0.5%. That is, in step S607, the frequency of the AC voltage is changed to 36.2 kHz, and the processing in step S602 and subsequent steps is repeated in step S608. Thereafter, the frequency of the AC voltage is increased in increments of 0.2 kHz, and the processes in steps S602 to S607 are repeated until the frequency reaches 44 kHz.

Next, in step S609, the AD _2DIF calculated for each frequency in step S604 is compared with a predetermined noise determination threshold value. If all AD _2DIF are smaller than the noise determination threshold value, the process proceeds to step S610, and AD _2DIF If even one value is equal to or greater than the noise determination threshold, the process returns to step S601. That is, _if the value of AD _2DIF is equal to or greater than the noise determination threshold, there is a high possibility that noise has been mixed in the detected data, so the process returns to step S601 and the measurement is repeated.

On the other hand, if all AD _{2DIF values} are smaller than the noise determination threshold value in step S609, the process proceeds to step S610. In step S610, it is determined whether or not the values of AD _{11 to} AD ₁₈ representing reverberation are monotonically decreasing. If all the frequencies are monotonically decreasing, the process proceeds to step S611, and if the monotonic decrease is not achieved. Return to step S601. As described above, when the detection circuit 12 picks up noise or the like, the detection waveform is disturbed, and the values of AD _{11 to} AD ₁₈ do not monotonously decrease. In this case, since the detected data has picked up noise or the like, the process returns to step S601 and the measurement is performed again.

Next, in step S611, selecting a frequency that becomes largest (sum SUM1 output voltage value AD ₁₁ to AD ₁₈₎ reverberation oscillation as the resonant frequency. Next, when there are a plurality of frequencies at which the reverberation vibration is maximum, the frequency at which the difference AD _2PP between the maximum value and the minimum value is the smallest is selected as the resonance frequency. When there are a plurality of frequencies having the same reverberation vibration and the difference AD _2PP between the maximum value and the minimum value, the lowest frequency is selected as the resonance frequency.

Further, in step S611, the total value SUM1 output voltage value AD ₁₁ to AD ₁₈ at a frequency reverberant vibration becomes largest is compared with a predetermined threshold value. If the total value SUM1 is smaller than the predetermined threshold value, the process returns to step S601 and the measurement is repeated. That is, when the reverberation vibration at the resonance frequency is significantly smaller than the reverberation vibration assumed in the design, the measurement may be performed again because the measurement may be incomplete. Since the frequency of the AC voltage applied to the piezoelectric element 4 is a value serving as a basis for touch detection, the frequency adjustment circuit 16d repeats the search for the resonance frequency until the frequency adjustment is successful. Note that the present invention may be configured to stop the process and issue an alarm if the process does not end even after a predetermined time has elapsed after the process of the flowchart of FIG. 26 starts.

  On the other hand, if the total value SUM1 is greater than or equal to a predetermined threshold value, the process proceeds to step S613. In step S613, the frequency selected in step S611 is determined as the frequency (drive frequency) of the AC voltage applied to the piezoelectric element 4, and the one-time process of the flowchart shown in FIG. The frequency determined by the flowchart shown in FIG. 26 is used in touch detection (step S403 in FIG. 23) as an initial value of the frequency of the AC voltage applied to the piezoelectric element 4.

Next, the resonance frequency confirmation process will be described with reference to FIGS. 27 and 28.
FIG. 27 is a resonance frequency confirmation flow called as a subroutine from the main flow shown in FIG. 23, and FIG. 28 is a resonance frequency detection flow called as a subroutine from the flowchart shown in FIG.

  As described above, in the touch detection device of the present embodiment, it is desirable that the frequency of the alternating voltage applied to the piezoelectric element 4 be in good agreement with the resonance frequency of the detection unit 2a. As described above, the frequency of the AC voltage is accurately adjusted by the frequency initial adjustment flow shown in FIG. 26 at the start of execution of the main flow (step S401 in FIG. 23). However, the resonance frequency of the detection unit 2a may change due to a temperature change of the detection unit 2a, adhesion of a water droplet or the like to the detection unit 2a, a secular change, or the like. For this reason, in the present embodiment, the resonance frequency of the detector 2a is confirmed at predetermined time intervals even during the execution of the main flow. Specifically, during the execution of the main flow, the processing proceeds from step S404 in FIG. 23 to step S405 every time one minute elapses, and the resonance frequency confirmation flow shown in FIG. 27 is executed as a subroutine from step S405.

First, in step S621 in FIG. 27, the resonance frequency detection flow shown in FIG. 28 is executed as a subroutine. As will be described later, in the resonance frequency detection flow shown in FIG. 28, the resonance frequency of the detection unit 2a is detected by a process similar to the above-described frequency initial adjustment flow (FIG. 26).
Next, in step S622 in FIG. 27, it is determined whether or not the resonance frequency has been successfully detected in the resonance frequency detection flow shown in FIG. If the detection of the resonance frequency has succeeded, the process proceeds to step S623, and if the detection of the resonance frequency has failed, the process proceeds to step S625.

Further, in step S623, it is determined whether or not the resonance frequency detected in step S621 matches the current frequency of the AC voltage applied to the piezoelectric element 4. In this embodiment, if the difference between the current frequency of the resonance frequency and the AC voltage is less than 0.5%, it is determined that there is no deviation between the resonance frequency and the frequency of the AC voltage, and the process proceeds to step S625.
If the difference between the resonance frequency and the current frequency of the AC voltage is 0.5% or more, it is determined that the resonance frequency and the frequency of the AC voltage are shifted, and the process proceeds to step S624. These determination results are used to determine whether or not there is a frequency shift in step S406 of the main flow shown in FIG.

  On the other hand, if it is determined in step S622 that the detection of the resonance frequency has failed, the process proceeds to step S625, where it is determined that “there is no deviation between the resonance frequency and the AC voltage”. In this case, the resonance frequency is not actually detected, but the main flow is in the middle of operation. Therefore, if the detection is repeated until the resonance frequency is successfully detected, the touch detection process is performed during that time. As a result, the function of the touch detection device is impaired. Therefore, in the present embodiment, even when the detection of the resonance frequency fails, the processing is performed as “no frequency shift” and the processing of the main flow is continued. In this embodiment, since the resonance frequency detection flow shown in FIG. 28 is executed at intervals of 1 minute, even if there is a single failure in detecting the resonance frequency, the function of the touch detection device is not hindered. Absent.

Next, the resonance frequency detection flow will be described with reference to FIG.
As shown in FIG. 28, the resonance frequency detection flow performs substantially the same processing as the frequency initial adjustment flow shown in FIG.
First, steps S631 to S638 of the resonance frequency detection flow shown in FIG. 28 correspond to steps S601 to S608 of the frequency initial adjustment flow shown in FIG. However, in the frequency initial adjustment flow (FIG. 26), the resonance frequency of the detection unit 2a was searched within ± 10% of the standard frequency Fr, whereas in the resonance frequency detection flow (FIG. 28), the resonance frequency was The difference is that the search is performed within a range of ± 3% of the frequency of the current AC voltage. That is, in the second adjustment mode, the frequency adjustment circuit 16d searches for the resonance frequency of the detection unit 2a within a second frequency range that is narrower than the first frequency range and includes the current AC voltage frequency.

  Here, in the frequency initial adjustment flow (FIG. 26), it is necessary to search for the resonance frequency corresponding to the individual difference of the detection unit 2a, the change of the model, or the like. On the other hand, in the resonance frequency detection flow (FIG. 28), it is sufficient to cope with the shift of the resonance frequency after the initial frequency adjustment, and the inventor's knowledge that the resonance frequency does not greatly shift after the initial frequency adjustment. It is based on. In addition, in the resonance frequency detection flow (FIG. 28), the time required to search for the resonance frequency can be shortened by setting a narrow range for searching for the resonance frequency.

  Also, steps S639 to S642 of the resonance frequency detection flow shown in FIG. 28 correspond to steps S609 to S612 of the frequency initial adjustment flow shown in FIG. That is, the determination circuit 16f realized by the microcomputer 16 determines the success or failure of the frequency adjustment by the frequency adjustment circuit 16d. However, in the initial frequency adjustment flow (FIG. 26: first adjustment mode), when noise or the like is mixed in the detected data (steps S609 and S610), or when the magnitude of reverberation vibration is not sufficient (steps). In S612), returning to the beginning of the flowchart, the detection was repeated. On the other hand, in the resonance frequency detection flow (FIG. 28) executed as the second adjustment mode, in these cases (steps S639, S640, S642), the “resonance frequency” is not repeated without repeating the search for the resonance frequency. It is determined as “detection failure” (step S645), and one process of the flowchart is ended.

  That is, in the determination circuit 16f, when the detected waveform includes a waveform whose waveform does not monotonously decrease after the application of the AC voltage is finished (step S640 → S645), the frequency adjustment by the frequency adjustment circuit 16d has failed. Is determined. Further, the determination circuit 16f also performs the frequency adjustment by the frequency adjustment circuit 16d even when the vibration energy of the detection unit 2a after the application of the AC voltage having the determined resonance frequency stops does not reach the predetermined threshold (step S642 → S645). Judge that it failed. Thus, therefore, when the detection of the resonance frequency fails, the current frequency of the alternating voltage is maintained.

  On the other hand, if the detection of the resonance frequency is successful (step S643), the frequency selected in step S641 is set as the current resonance frequency of the detection unit 2a (step S644), and once in the flowchart shown in FIG. Terminate the process. The resonance frequency set in step S644 of FIG. 28 is compared with the current frequency of the AC voltage applied to the piezoelectric element 4 in step S623 of the resonance frequency detection flow shown in FIG. Used for judgment.

Next, the frequency readjustment flow of the AC voltage will be described with reference to FIG.
As described above, during the operation of the main flow (FIG. 23), the resonance frequency of the detection unit 2a is detected and compared with the frequency of the current AC voltage to determine whether or not a frequency deviation has occurred. (Step S406 in FIG. 23). However, as will be described below, even if a frequency shift is detected, the frequency of the AC voltage is not immediately changed so as to coincide with the resonance frequency.

  For example, in a situation where the resonance frequency of the detection unit 2a is lowered due to water droplets adhering to the detection unit 2a, the resonance frequency is restored to the original frequency in a relatively short time due to the drop of water or evaporation. Return. Even when the resonance frequency is changed by applying cold water or hot water to the detection unit 2a, the resonance frequency returns to the original frequency in a relatively short time if the temperature of the detection unit 2a returns to room temperature. For this reason, if the frequency of the AC voltage is changed each time a change in the resonance frequency is detected, the frequency of the AC voltage to be applied becomes unstable or the difference between the frequency of the resonance frequency and the AC voltage due to a time lag. May become large. Therefore, in the present embodiment, the frequency (drive frequency) of the AC voltage is readjusted based on the continuation state of the deviation between the resonance frequency and the frequency of the AC voltage by the frequency readjustment flow.

  As described above, when it is determined that a frequency shift has occurred between the resonance frequency of the detection unit 2a and the frequency of the current AC voltage, the time during which the frequency shift continues is integrated. (Step S419 in FIG. 23). While this frequency deviation is continuing, the AC voltage frequency readjustment flow shown in FIG. 29 is executed every minute (step S421 in FIG. 23).

First, in step S651 of FIG. 29, the above-described resonance frequency detection flow (FIG. 28) is executed as a subroutine.
Next, in step S652, it is determined whether or not the resonance frequency detection executed in step S651 has succeeded. If successful, the process proceeds to step S653, and if unsuccessful, the process proceeds to step S656.

  In step S656, readjustment of the frequency (drive frequency) of the AC voltage applied to the piezoelectric element 4 is not executed, and the one-time process of the flowchart shown in FIG. 29 is terminated while maintaining the current frequency. That is, if the frequency of the AC voltage is changed in a state where a highly reliable detection result is not obtained in the resonance frequency detection, the frequency of the AC voltage may deviate from the resonance frequency due to a measurement error or the like.

  On the other hand, if the detection of the resonance frequency is successful, the process proceeds to step S653. In step S653, the resonance frequency detected in step S651 is compared with the frequency of the current AC voltage. When the resonance frequency is lower than the frequency of the AC voltage, the process proceeds to step S655, and when the resonance frequency is equal to or higher than the frequency of the AC voltage, the process proceeds to step S654.

  In step S654, it is determined whether or not the accumulated duration of the frequency deviation is 5 minutes or more, which is the frequency deviation determination time. If the duration is 5 minutes or more, the process proceeds to step S657. If the duration is not 5 minutes or more, the process proceeds to step S656. In step S656, the readjustment of the frequency of AC voltage (drive frequency) is not executed, and the one-time process of the flowchart shown in FIG. 29 is terminated while the current frequency is maintained. That is, if the frequency deviation does not continue for more than 5 minutes, the resonance frequency may return to the original frequency by leaving the frequency deviation as it is.

  On the other hand, if the duration time of the frequency deviation is 5 minutes or more, the process proceeds to step S657. In step S657, the frequency (drive frequency) of the alternating voltage applied to the piezoelectric element 4 is changed (readjusted), and the step is performed. It is made to correspond to the resonance frequency detected in S651. As described above, when the frequency shift between the resonance frequency and the frequency of the AC voltage is detected by the frequency shift detection circuit 16e, the frequency adjustment circuit 16d causes the frequency (drive frequency) of the AC voltage to match the resonance frequency. Adjust to. However, the frequency adjustment by the frequency adjustment circuit 16d is executed when the state in which the frequency deviation is detected by the frequency deviation detection circuit 16e continues for a predetermined frequency deviation determination time or longer.

  On the other hand, if the resonance frequency is lower than the frequency of the AC voltage, the process proceeds to step S655. In step S655, it is determined whether the accumulated duration of the frequency deviation is 30 minutes or more, which is the frequency deviation determination time. If the duration of the frequency shift is 30 minutes or more, the process proceeds to step S657, and if it is not 30 minutes or more, the process proceeds to step S656. As described above, in step S656, readjustment of the frequency (drive frequency) of the AC voltage is not executed. In step S657, the frequency of AC voltage (drive frequency) is made to coincide with the resonance frequency.

  Thus, in this embodiment, when the resonance frequency is higher than the frequency of the AC voltage (step S654) and when it is lower (step S655), the frequency deviation determination time is different, and the resonance frequency is the frequency of the AC voltage. If it is lower, the frequency deviation determination time is set longer than when it is higher. That is, when the resonance frequency is lower than the frequency of the AC voltage (step S655), the most likely state is a state in which the resonance frequency is lowered due to water droplets adhering to the detection unit 2a. On the other hand, when the resonance frequency is higher than the frequency of the AC voltage (step S654), the most likely state is that water droplets have adhered to the detection unit 2a in the past, and the frequency of the AC voltage is lowered accordingly. Thereafter, the water droplets drop off or evaporate and the resonance frequency is increased.

  For this reason, when the resonance frequency is higher than the frequency of the AC voltage, it is preferable to match the frequency of the AC voltage with the true resonance frequency relatively early. On the other hand, when the resonance frequency is lower than the frequency of the AC voltage, even if the frequency deviation is left, the resonance frequency is gradually restored to the frequency of the AC voltage by dropping or evaporating water droplets little by little. There is a high possibility of going. For this reason, when the resonance frequency is lower than the frequency of the AC voltage, it is preferable to take a longer frequency deviation determination time to prevent the frequency of the AC voltage from becoming unstable.

  According to the touch detection device of the third embodiment of the present invention, the touch detection device includes the frequency shift detection circuit 16e that detects the occurrence of shift between the resonance frequency of the detection unit 2a and the frequency of the AC voltage applied to the piezoelectric element 4, When the frequency deviation is detected by the frequency deviation detection circuit 16e, the frequency adjustment circuit 16d performs adjustment so that the frequency of the AC voltage matches the resonance frequency of the detection unit (steps S406 → S419 → S420 → S421 in FIG. 23). Therefore, it is possible to always keep the touch detection device in a good state by monitoring the frequency shift.

  Further, according to the touch detection device of the present embodiment, the frequency adjustment circuit 16d adjusts the frequency when the state in which the frequency shift is detected by the frequency shift detection circuit 16e continues for a predetermined frequency shift determination time or longer. (Steps S654 → S657 and Steps S655 → S657 in FIG. 29), automatic adjustment by the frequency adjustment circuit 16d can be performed more reliably.

  Furthermore, according to the touch detection device of the present embodiment, the frequency deviation determination time is when the resonance frequency of the detection unit 2a is lower than the frequency of the AC voltage applied to the piezoelectric element 4 (steps S653 → S655 in FIG. 29). Is set longer than the case where the resonance frequency of the detection unit 2a is higher than the frequency of the AC voltage applied to the piezoelectric element 4 (steps S653 → S654 in FIG. 29). It can effectively deal with changes.

  Further, according to the touch detection device of the present embodiment, in the first adjustment mode (FIG. 26), the resonance frequency is within the first frequency range (± 10% of the standard frequency) including the standard frequency of the detection unit 2a. In the second adjustment mode (FIG. 28), a second frequency range (± 3% of the frequency of the current AC voltage) that is narrower than the first frequency range, including the frequency of the current AC voltage. Since the resonance frequency is searched for, the adjustment according to the cause of the frequency deviation can be performed in a short time.

  Furthermore, according to the touch detection device of the present embodiment, in the first adjustment mode (FIG. 26), when the frequency adjustment fails, the resonance frequency is repeatedly searched until it succeeds (steps S609 → S601 in FIG. 26). , S610 → S601, S612 → S601), in the second adjustment mode (FIG. 28), when the frequency adjustment fails, the frequency of the current AC voltage is maintained without repeating the search for the resonance frequency ( Steps S639 → S645, S640 → S645, S642 → S645 in FIG. 28), it is possible to perform appropriate frequency adjustment according to the occurrence of frequency deviation and the use situation of the touch detection device, and reliable frequency adjustment, It is possible to achieve both reduction of the unusable period.

  Further, according to the touch detection device of the present embodiment, when the detection waveform includes a waveform whose waveform does not monotonously decrease after the application of the AC voltage (the lower stage in FIG. 31), the frequency adjustment circuit Since it is determined that the frequency adjustment has failed (step S610 in FIG. 26 and step S640 in FIG. 28), erroneous frequency adjustment due to the influence of noise or the like can be prevented.

  Furthermore, according to the touch detection device of the present embodiment, when the vibration energy of the detection unit 2a after stopping the application of the alternating voltage of the determined resonance frequency does not reach the predetermined threshold, the frequency adjustment by the frequency adjustment circuit is performed. Since it is determined that the process has failed (steps S612 → S601 in FIG. 26, steps S642 → S645 in FIG. 28), it is possible to prevent erroneous frequency adjustment due to frequency adjustment in an inappropriate environment. For example, even when the user touches the detection unit 2a during frequency adjustment, erroneous frequency adjustment can be prevented.

  Further, according to the touch detection device of the present embodiment, as the contact determination confirmation operation (FIG. 25), an AC voltage having a confirmation frequency (steps S541 and S543 in FIG. 25) different from the frequency of the normal AC voltage is applied to the piezoelectric element 4. When the contact determination circuit 16a determines the contact of the object also by applying an alternating voltage with a confirmation frequency, the determination of the contact with the detection unit 2a is confirmed. For this reason, even when the contact determination circuit 16a erroneously determines the contact of the object due to the frequency shift, the contact determination confirmation circuit 16b performs excitation with an AC voltage having a confirmation frequency different from the frequency of the normal AC voltage. Therefore, even when the resonance frequency is shifted, a large reverberation vibration is excited, and erroneous detection due to the frequency shift can be effectively suppressed.

  As mentioned above, although preferable embodiment of this invention was described, a various change can be added to embodiment mentioned above. In particular, in the embodiment described above, the present invention has been applied to the detection of the switching operation of water discharge and water stop of the faucet device, but in addition to switching of water discharge and water stop, the water discharge form (shower water discharge, straight water discharge, etc. ) Switching, flow rate adjustment operation, temperature adjustment operation, etc., the present invention can be applied to detection of any operation. Further, in the present embodiment, the touch detection device is applied to the faucet device in which the water discharge unit is fixed. However, the touch detection device of the present invention is a pull-out type faucet device that can be pulled out by the water discharge head. It can also be applied. In this case, a signal line is built in along the hose drawn out from the faucet device body, and the detection unit provided at the tip of the water discharge head and the detection circuit arranged under the counter board are electrically connected. Can be connected. Further, in the present embodiment, the touch detection device is applied to the faucet device, but the present invention is applied to any watering device such as a water discharge device, a flow rate adjustment device, a temperature adjustment device, and a device combining these. Can be applied.

  In the above-described embodiment, the piezoelectric element is used as the vibration excitation element. However, any element or device that can excite vibration in the detection unit can be used as the vibration excitation element. Further, in the above-described embodiment, after the vibration is excited in the detection unit by the piezoelectric element, the reverberation vibration is detected by the piezoelectric element. However, the reverberation of the detection unit is separated from the element or device for exciting the vibration. An element or device for detecting vibrations can also be provided. In the above-described embodiment, an AC voltage is applied to one terminal of the piezoelectric element and a signal for detecting reverberation vibration is acquired from the same terminal. The reverberation vibration detection terminal can be provided separately from the AC voltage application terminal.

  Furthermore, in the above-described embodiment, the frequency of the alternating voltage applied to the piezoelectric element is matched with the resonance frequency of the detection unit and the piezoelectric element that vibrate integrally, but the frequency of the alternating voltage matches the resonant frequency. It does not have to be. In other words, even if these frequencies are different, the reverberation vibration is smaller when the detection unit is touched than when the detection unit is not touched. Therefore, detecting the touch based on the reverberation vibration is in principle. Is possible. In the above-described embodiment, the AC voltage is directly applied to the piezoelectric element by switching the two transistors. However, the AC voltage may be applied to the piezoelectric element via a step-up transformer or a capacitor. it can.

DESCRIPTION OF SYMBOLS 1 Faucet device of 1st Embodiment of this invention 2 Faucet body 2a Detection part 2b Water outlet 4 Piezoelectric element (vibration excitation element)
4a, 4b Signal line 6 Hot and cold water mixing valve 8a Hot water solenoid valve (open / close valve)
8b Solenoid valve for water (open / close valve)
DESCRIPTION OF SYMBOLS 10 Water faucet controller 12 Detection circuit 14a Hot water supply pipe 14b Water supply pipe 16 Microcomputer 16a Contact determination circuit 16b Contact determination confirmation circuit 16c Abnormality detection circuit 16d Frequency adjustment circuit 16e Frequency deviation detection circuit 16f Determination circuit 18 Drive circuit 18a PNP transistor 18b NPN transistor 18c, 18d Electric resistance 20 Signal conversion circuit 20a, 20b Capacitor 20c Diode 20d Electric resistance 22 Voltage dividing circuit 22a, 22b Electric resistance

Claims (23)

A touch detection device for use in a water tool,
A detection unit for detecting contact of an object;
A vibration excitation element attached to the detection unit;
A drive circuit for exciting vibration in the detection unit by intermittently applying an alternating voltage of a predetermined frequency to the vibration excitation element;
A contact determination circuit that determines whether or not an object has contacted the detection unit, based on vibration of the detection unit after application of an alternating voltage to the vibration excitation element by the drive circuit is stopped;
A touch detection device comprising:   The vibration excitation element is configured by a piezoelectric element, and the contact determination circuit determines whether the object is based on an output signal from the vibration excitation element after the application of an alternating voltage to the vibration excitation element is stopped. The touch detection device according to claim 1, wherein it is determined whether or not the detection unit is touched.   The vibration excitation element includes an input terminal to which an AC voltage is applied by the drive circuit, an output signal from the vibration excitation element is obtained from the input terminal of the vibration excitation element, and an output of the drive circuit is The touch detection device according to claim 2, wherein the impedance becomes high impedance after the application of AC voltage is stopped.   The contact determination circuit is configured to determine whether an object has contacted the detection unit based on vibration energy of the detection unit after the application of AC voltage by the drive circuit is stopped, and the vibration energy is The touch detection device according to any one of claims 1 to 3, wherein it is determined that an object has come into contact when the value is equal to or less than a predetermined threshold value.   The contact determination circuit is configured to determine whether an object has contacted the detection unit based on a vibration amplitude of the detection unit after the application of AC voltage by the drive circuit is stopped, and the vibration amplitude is The touch detection device according to any one of claims 1 to 3, wherein the touch detection device determines that the target object has contacted when the time until the attenuation is equal to or less than a predetermined amplitude is equal to or less than the predetermined time.   The contact determination circuit is configured to determine whether or not an object has contacted the detection unit based on a vibration amplitude of the detection unit after the application of AC voltage by the drive circuit is stopped. The touch according to any one of claims 1 to 3, wherein the touch of the object is determined when the vibration amplitude after a predetermined time has passed after the application of the alternating voltage is attenuated to a predetermined amplitude or less. Detection device.   The contact determination circuit includes an abnormality detection circuit for preventing erroneous detection, and the abnormality detection circuit detects an abnormality based on an output signal from the vibration excitation element during application of an AC voltage to the vibration excitation element. The touch detection device according to any one of claims 2 to 6.   The abnormality detection circuit detects an abnormality when the amplitude of the output signal during application of an alternating voltage to the vibration excitation element is larger than the amplitude in a normal state, and the contact determination circuit detects an abnormality. The touch detection device according to claim 7, wherein the touch detection device does not determine that the object has touched.   The abnormality detection circuit detects an abnormality when the amplitude of the output signal fluctuates by a predetermined value or more during application of an AC voltage to the vibration excitation element, and the contact determination circuit detects an abnormality. The touch detection device according to claim 7, wherein the touch detection device does not determine that the object has touched.   Furthermore, a contact determination confirmation circuit is provided. The contact determination confirmation circuit executes a contact determination confirmation operation that further reduces the possibility of erroneous detection after the contact determination circuit once determines that an object has contacted. The touch detection device according to any one of claims 1 to 9.   The contact determination confirmation circuit applies, as the contact determination confirmation operation, an AC voltage to the vibration excitation element for a predetermined confirmation period longer than normal AC voltage application, and outputs from the vibration excitation element during the confirmation period. The touch detection device according to claim 10, wherein contact determination by the contact determination circuit is confirmed based on a signal.   Furthermore, it has a frequency adjustment circuit that adjusts the frequency of the AC voltage applied to the vibration excitation element, and this frequency adjustment circuit is configured to adjust the frequency of the AC voltage applied to the frequency at which the detection unit to which the vibration excitation element is attached resonates. The touch detection device according to claim 1, wherein the frequency is adjusted.   The frequency adjusting circuit executes application of alternating voltage for a predetermined time multiple times at different frequencies, and sets the frequency at which the amplitude of the output signal from the vibration exciting element after the application of alternating voltage is maximum becomes the vibration exciting element. The touch detection device according to claim 12, wherein the frequency is determined as a frequency at which the detection unit to which the sensor is attached resonates.   In the case where there are a plurality of frequencies at which the amplitude of the output signal becomes maximum after stopping the application of the AC voltage, the frequency adjustment circuit applies the AC voltage to the vibration excitation element among the frequencies having the maximum amplitude. The touch detection device according to claim 13, wherein the frequency with the smallest fluctuation in the amplitude of the output signal is determined as the frequency at which the detection unit to which the vibration excitation element is attached resonates.   Furthermore, a frequency deviation detection circuit that detects occurrence of deviation between the resonance frequency of the detection unit and the frequency of the AC voltage applied to the vibration excitation element is provided, and the frequency adjustment circuit uses the frequency deviation detection circuit to generate a frequency difference. The touch detection device according to claim 12, wherein when a shift is detected, adjustment is performed so that the frequency of the AC voltage matches the resonance frequency of the detection unit.   The touch detection device according to claim 15, wherein the frequency adjustment circuit performs frequency adjustment when a state in which the frequency shift is detected by the frequency shift detection circuit continues for a predetermined frequency shift determination time or longer.   When the resonance frequency of the detection unit is lower than the frequency of the AC voltage applied to the vibration excitation element, the frequency deviation determination time is equal to the frequency of the AC voltage applied to the vibration excitation element. The touch detection device according to claim 16, wherein the touch detection device is set longer than a case where the height is higher.   The frequency adjustment circuit is configured to search for a resonance frequency of the detection unit within a predetermined frequency range, and is configured to be able to execute a first adjustment mode and a second adjustment mode having different frequency ranges to be searched. In the first adjustment mode, the resonance frequency is searched for in the first frequency range including the standard frequency of the detection unit, and in the second adjustment mode, the frequency of the current AC voltage is included. 18. The touch detection device according to claim 15, wherein a resonance frequency is searched for in a second frequency range narrower than the first frequency range.   And a determination circuit for determining success or failure of the frequency adjustment by the frequency adjustment circuit. In the first adjustment mode, the frequency adjustment is successful when the determination circuit determines that the frequency adjustment has failed. In the second adjustment mode, when the determination circuit determines that the frequency adjustment has failed, the frequency of the current AC voltage is determined without repeating the search for the resonance frequency. The touch detection device of claim 18, maintained.   The frequency adjustment circuit applies an AC voltage to the vibration excitation element for a plurality of frequencies within a predetermined frequency range, and obtains output signals from the vibration excitation element when an AC voltage is applied, respectively. The frequency adjustment is performed by analyzing the detection waveform of the output signal, and the determination circuit includes the detection waveform that does not monotonously decrease after the application of the AC voltage is completed. The touch detection device according to claim 19, wherein the frequency adjustment by the frequency adjustment circuit is determined to have failed.   The frequency adjustment circuit applies an AC voltage to the vibration excitation element for a plurality of frequencies within a predetermined frequency range, and obtains output signals from the vibration excitation element when an AC voltage is applied, respectively. The resonance circuit is configured to search and determine the resonance frequency based on the output signal, and the determination circuit does not reach a predetermined threshold value of the vibration energy of the detection unit after the application of the AC voltage having the determined resonance frequency is stopped. The touch detection device according to claim 19, wherein the frequency adjustment by the frequency adjustment circuit is determined to have failed.   After the contact determination circuit once determines that the object is in contact with the contact determination confirmation circuit, as the contact determination confirmation operation, an AC voltage having a confirmation frequency different from the frequency of a normal AC voltage is used as the vibration excitation. The touch detection according to claim 10, wherein the detection of the contact with the detection unit is confirmed when the contact is determined by the contact determination circuit even when the alternating voltage of the confirmation frequency is applied to the element. apparatus. A faucet device capable of switching between water discharge and water stop by touch operation,
The touch detection device according to any one of claims 1 to 22,
An operation unit having the detection unit;
A faucet device comprising: an on-off valve that is opened and closed based on contact determination of an object to the detection unit by the touch detection device.

Images