Abstract: A sound sensor, a hydrophone including the sound sensor, and a pressure balancing device for using for the hydrophone are provided. The hydrophone includes: a sensor including a sensing part and a pressure balancing part; a printed circuit board (PCB) that is electrically connected to the sensor; a case that houses the sensor and the PCB and that has an opening at one side thereof; an elastic membrane that covers the opening of the case; and a signal line that is electrically connected to the PCB to be extended to the outside of the case. The pressure balancing part includes a diaphragm of a thin film and a support that supports the diaphragm. A pressure balancing hole is formed at one side of the pressure balancing part, and at the inside of the pressure balancing part, a channel that is connected to the pressure balancing hole is formed, and a compressible gas is filled in the channel.

Abstract: A sound generator includes a transducer converting electric energy to mechanical energy, a mechanical amplifier mechanically amplifying a vibration generated in a piezoelectric component of the transducer, and a radiation plate radiating a sound wave from a signal amplified by the mechanical amplifier, wherein the radiation plate includes a first step having a height for compensating for a first resonance frequency and a second step having a height for compensating for a second resonance frequency.

Abstract: A sound sensor, a hydrophone including the sound sensor, and a pressure balancing device for using for the hydrophone are provided. The hydrophone includes: a sensor including a sensing part and a pressure balancing part; a printed circuit board (PCB) that is electrically connected to the sensor; a case that houses the sensor and the PCB and that has an opening at one side thereof; an elastic membrane that covers the opening of the case; and a signal line that is electrically connected to the PCB to be extended to the outside of the case. The pressure balancing part includes a diaphragm of a thin film and a support that supports the diaphragm. A pressure balancing hole is formed at one side of the pressure balancing part, and at the inside of the pressure balancing part, a channel that is connected to the pressure balancing hole is formed, and a compressible gas is filled in the channel.

Abstract: A sound generator includes a transducer converting electric energy to mechanical energy, a mechanical amplifier mechanically amplifying a vibration generated in a piezoelectric component of the transducer, and a radiation plate radiating a sound wave from a signal amplified by the mechanical amplifier, wherein the radiation plate includes a first step having a height for compensating for a first resonance frequency and a second step having a height for compensating for a second resonance frequency.

Abstract: A multiple resonances type ultrasonic transducer for a ranging measurement with high directionality using a parametric transmitting array in air, includes an ultrasonic actuator unit formed with a regularly mixing array of first unit actuators having a resonance frequency of f1 and second unit actuators having a resonance frequency of f2. The ultrasonic actuator unit generates a difference frequency wave (fd=f1?f2) with high directionality by forming a parametric transmitting array in air through generating two ultrasonic waves with high pressure in air. Further, the transducer includes an ultrasonic sensor unit formed with one or more unit sensors having a resonance frequency of the difference frequency (fd=f1?f2), for sensing a reflected ultrasonic pulse signal from a target.

Abstract: A multiple resonances type ultrasonic transducer for a ranging measurement with high directionality using a parametric transmitting array in air, includes an ultrasonic actuator unit formed with a regularly mixing array of first unit actuators having a resonance frequency of f1 and second unit actuators having a resonance frequency of f2. The ultrasonic actuator unit generates a difference frequency wave (fd=f1?f2) with high directionality by forming a parametric transmitting array in air through generating two ultrasonic waves with high pressure in air. Further, the transducer includes an ultrasonic sensor unit formed with one or more unit sensors having a resonance frequency of the difference frequency (fd=f1?f2), for sensing a reflected ultrasonic pulse'signal from a target.

Abstract: An ultrasonic ranging method for measuring a distance to an object in an air includes the steps of generating a first and a second primary ultrasonic waves having a frequency f1 and f2, respectively, transmitting the first and the second primary ultrasonic waves in a same direction, wherein a secondary ultrasonic wave having a frequency corresponding to the difference of two frequencies fd=f1?f2 is created by a nonlinear property of the air and radiated to the object, detecting an echo pulse of the secondary ultrasonic wave reflected from the object, and measuring the distance to the object based on a propagation time of the secondary wave.

Abstract: An ultrasonic ranging method for measuring a distance to an object in an air includes the steps of generating a first and a second primary ultrasonic waves having a frequency f1 and f2, respectively, transmitting the first and the second primary ultrasonic waves in a same direction, wherein a secondary ultrasonic wave having a frequency corresponding to the difference of two frequencies fd=f1?f2 is created by a nonlinear property of the air and radiated to the object, detecting an echo pulse of the secondary ultrasonic wave reflected from the object, and measuring the distance to the object based on a propagation time of the secondary wave.