Ultrasonic distance measuring apparatus
First Claim
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1. An ultransonic distance measuring apparatus comprising:
- a transmitter for transmitting an ultransonic wave toward an object;
a receiver for receiving an aultrasonic wave reflected from said object;
comparator means for comparing a predetermined reference level with the level of a reflection signal electrically converted from said reflected wave and producing a receiving signal when the level of said reflection signal exceeds said reference level, thereby enabling a time to be determined from the transmission of said ultrasonic wave to the receiving of the reflected wave representing the distance to said object; and
an atmospheric characteristic compensating means for compensating for a variation of a propagation characteristic of said ultrasonic wave due to a variation of an atmospheric characteristic, said compensating means comprising a sensor means for detecting a characteristic of the atmosphere through which said ultrasonic wave is propagated, a reference voltage generator circuit having a capacitor connected with said sensor means adapted to be charged to a predetermined voltage and to be discharged through and under control of said sensor means responsive to the detected characteristic of the atmosphere in order to supply said reference level to said comparator means, and a switching element for controlling the charge period of said capacitor.
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Abstract
In an ultrasonic distance measuring apparatus producing distance data representing a distance to an object by transmitting and receiving an ultrasonic wave, a sensor detects variation in the temperature and/or humidity of the atmosphere, and a compensator compensates for variation in propagation characteristic of the ultrasonic wave caused by the variation in the temperature and/or humidity respectively.
46 Citations
8 Claims
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1. An ultransonic distance measuring apparatus comprising:
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a transmitter for transmitting an ultransonic wave toward an object; a receiver for receiving an aultrasonic wave reflected from said object; comparator means for comparing a predetermined reference level with the level of a reflection signal electrically converted from said reflected wave and producing a receiving signal when the level of said reflection signal exceeds said reference level, thereby enabling a time to be determined from the transmission of said ultrasonic wave to the receiving of the reflected wave representing the distance to said object; and an atmospheric characteristic compensating means for compensating for a variation of a propagation characteristic of said ultrasonic wave due to a variation of an atmospheric characteristic, said compensating means comprising a sensor means for detecting a characteristic of the atmosphere through which said ultrasonic wave is propagated, a reference voltage generator circuit having a capacitor connected with said sensor means adapted to be charged to a predetermined voltage and to be discharged through and under control of said sensor means responsive to the detected characteristic of the atmosphere in order to supply said reference level to said comparator means, and a switching element for controlling the charge period of said capacitor. - View Dependent Claims (2, 3, 4, 5)
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6. An ultrasonic distance measuring apparatus, comprising:
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a transmitter for transmitting an ultrasonic wave toward an object; a receiver for receiving an ultrasonic wave reflected from said object; comparator means for comparing a predetermined reference level with the level of a reflection signal electrically converted from said reflected wave and producing a receiving signal when the level of said reflection signal exceeds said reference level, thereby enabling a time to be determined from the transmission of said ultrasonic wave to the receiving of the reflected wave representing the distance to said object; and an atmospheric characteristic compensating means for compensating for a variation of a propagation characteristic of said ultrasonic wave due to a variation of an atmospheric characteristic, said compensating means comprising sensor means for detecting a characteristic of the atmosphere through which said ultrasonic wave is propagated, and control circuit means for changing a transmission level characteristic of the ultrasonic wave transmitted from said transmitter in response to the atmosphere characteristic detected by said sensor means. - View Dependent Claims (7, 8)
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Specification