Ultrasonic sensor transmitting and receiving ultrasonic frequencies adjusted according to temperature
First Claim
1. An ultrasonic sensor comprising:
- a receiving member for receiving ultrasonic waves;
a vibrator for converting the ultrasonic waves to electrical signals;
a filter device for selecting electrical signals in a predetermined frequency region from the electrical signals converted by the vibrator; and
a temperature sensor for detecting ambient temperature of the receiving member, wherein;
the predetermined frequency region is changed according the ambient temperature, so that the frequency region of the electrical signals selected by the filter device always includes a resonant frequency of the receiving member.
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Accused Products
Abstract
Components of an ultrasonic sensor are contained in a cylindrical casing having an end wall closing one end of the casing. A vibrator such as a piezoelectric element is disposed in the casing in contact with the end wall. An integrated circuit chip that includes a signal generator, a filter device and a temperature sensor is contained in the casing. Vibrations generated in the vibrator are transferred to the end wall that transmits ultrasonic waves. Ultrasonic waves received by the end wall are converted into electrical signals in the vibrator. Frequency of the transmitting signals and a frequency region of the signals to be received are controlled according to the ambient temperature, so that they always coincide with a resonant frequency of the end wall which changes according to the ambient temperature. Thus, high transmitting/receiving efficiency is always realized, irrespective of the ambient temperature.
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Citations
11 Claims
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1. An ultrasonic sensor comprising:
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a receiving member for receiving ultrasonic waves; a vibrator for converting the ultrasonic waves to electrical signals; a filter device for selecting electrical signals in a predetermined frequency region from the electrical signals converted by the vibrator; and a temperature sensor for detecting ambient temperature of the receiving member, wherein; the predetermined frequency region is changed according the ambient temperature, so that the frequency region of the electrical signals selected by the filter device always includes a resonant frequency of the receiving member. - View Dependent Claims (2)
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3. An ultrasonic sensor comprising:
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a transmitting vibrator for converting transmitting electrical signals to transmitting vibrations; a receiving vibrator for converting receiving vibrations to receiving electrical signals; a signal generator for generating the transmitting electrical signals having a predetermined frequency to be supplied to the transmitting vibrator; a filter device for selecting electrical signals in a predetermined frequency region from the receiving electrical signals; a transmitting and receiving member for transmitting ultrasonic waves formed from the transmitting vibrations and for receiving ultrasonic waves to be supplied to the receiving vibrator; and a temperature sensor for detecting ambient temperature of the transmitting and receiving member, wherein; the predetermined frequency of the transmitting electrical signals is changed according to the ambient temperature, so that the frequency of the transmitting electrical signals coincides with a resonant frequency of the transmitting and receiving member; and the predetermined frequency region of the electrical signals selected by the filter device is changed according the ambient temperature, so that the frequency region always includes a resonant frequency of the transmitting and receiving member. - View Dependent Claims (4, 5, 6, 7, 8, 9, 10, 11)
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Specification