Touch detection device used in water handling equipment, and faucet apparatus including the same

A touch detection device used in water handling equipment, comprising:

• a sensing portion for sensing contact with a target object;
• a vibration excitation element attached to the sensing portion;
• a drive circuit for exciting a vibration in the sensing portion by intermittently applying an AC voltage at a predetermined frequency to the vibration excitation element;
• and
• a contact determination circuit configured to determine whether the target object has contacted the sensing portion based on vibration of the sensing portion after application of the AC voltage to the vibration excitation element by the drive circuit;
• wherein the vibration excitation element comprises a piezo-electric element, and the contact determination circuit determines whether the target object has contacted the sensing portion based on an output signal from the vibration excitation element detected after stopping of the application of the AC voltage to the vibration excitation element;
• wherein the vibration excitation element comprises an input terminal to which the AC voltage is applied by the drive circuit, the output signal from the vibration excitation element is obtained from the input terminal of the vibration excitation element, and the output of the drive circuit becomes high impedance after application of the AC voltage stops;
• and
• wherein the contact determination circuit comprises an anomaly sensing circuit configured to prevent false sensing, and the anomaly sensing circuit senses an anomaly based on the output signal from the vibration excitation element detected during application of the AC voltage to the vibration excitation element.

A touch detection device used in water handling equipment, comprising:

• a sensing portion for sensing contact with a target object;
• a vibration excitation element attached to the sensing portion;
• a drive circuit for exciting a vibration in the sensing portion by intermittently applying an AC voltage at a predetermined frequency to the vibration excitation element;
• a contact determination circuit configured to determine whether the target object has contacted the sensing portion based on vibration of the sensing portion after application of the AC voltage to the vibration excitation element by the drive circuit;
• and
• a frequency adjustment circuit configured to adjust the frequency of the AC voltage applied to the vibration excitation element wherein the frequency adjustment circuit adjusts the frequency of the AC voltage to a resonant frequency of the sensing portion, to which the vibration excitation element is attached;
• wherein the vibration excitation element comprises a piezo-electric element, and the contact determination circuit determines whether the target object has contacted the sensing portion based on an output signal from the vibration excitation element detected after stopping of the application of the AC voltage to the vibration excitation element;
• wherein the vibration excitation element comprises an input terminal to which the AC voltage is applied by the drive circuit, the output signal from the vibration excitation element is obtained from the input terminal of the vibration excitation element, and the output of the drive circuit becomes high impedance after application of the AC voltage stops;
• and
• wherein the frequency adjustment circuit applies the AC voltage for a predetermined period multiple times at different frequencies, and the frequency at which the amplitude of the output signal from the vibration excitation element is maximal following the stopping of the AC voltage application, is determined by the frequency adjustment circuit to be the mechanical resonant frequency of the sensing portion, to which the vibration excitation element is attached.