| 摘要 |
PURPOSE:To calculate accurately a distance to an object located in the front even when any change occurs in the shape thereof, by a method wherein ultrasonic waves emitted by a plurality of ultrasonic oscillators are detected by ultrasonic detectors and the shape of the object is discriminated on the basis of detection patterns obtained therefrom. CONSTITUTION:An ultrasonic wave emitted from an ultrasonic oscillator T1 is reflected by an edge Q of an object and reaches ultrasonic detectors R1, R2,...R6. An ultrasonic wave emitted from an ultrasonic oscillator T2 reaches the detectors R1, R2,...R6. A control circuit 3 is so programmed that Data 2 outputted by a signal comparator circuit S in the case of emission from the oscillator T1 are compared with Data 2 outputted by the circuit S in the case of emission from the oscillator T2 and that the shape of an object is identified as in an edge state when these data have the same or adjacent detector numbers, while it is identified as in a flat state when the data have numbers other than the above. Then, a distance between an operator and the object is calculated by using Data 1 on the time for propagation of the ultrasonic waves which is counted by counter circuits C1, C2,...Cn.
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