Apparatus for detecting the number of objects
First Claim
1. An apparatus for detecting the number of objects comprising first means for emitting an ultrasonic wave signal toward said objects, second means for receiving a reflection wave signal from said objects and converting the latter to a first electric pulsating signal including pulses representative of each of said objects, third means for generating a reference level signal, wave shaping means having respective input terminals connected with said second means and said reference level setting means for producing a second electric pulsating signal including all those pulses of said first electric pulsating signal having peak values higher than said reference level signal to the exclusion of the other pulses of said first electric pulsating signal, and means responsive to said second electric pulsating signal for producing an output signal proportional to the pulses in said second electric pulsating signal.
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Abstract
Apparatus for detecting the number of objects such as the number of persons located within a predetermined area. Ultrasonic wave is emitted toward the objects, the number of which is to be determined, and the reflected waves from the objects are received by a receiver. Among the received reflection waves, the waves having an amplitude greater than a predetermined peak value are derived as the useful reflection wave signal having a constant peak value. The number of the objects is determined based on the quantity of the derived reflection wave signals having the constant peak value. By emitting the ultrasonic wave for every unit time, the derived reflection wave signals having the constant peak value may be averaged by means of a smoothing circuit.
20 Citations
11 Claims
- 1. An apparatus for detecting the number of objects comprising first means for emitting an ultrasonic wave signal toward said objects, second means for receiving a reflection wave signal from said objects and converting the latter to a first electric pulsating signal including pulses representative of each of said objects, third means for generating a reference level signal, wave shaping means having respective input terminals connected with said second means and said reference level setting means for producing a second electric pulsating signal including all those pulses of said first electric pulsating signal having peak values higher than said reference level signal to the exclusion of the other pulses of said first electric pulsating signal, and means responsive to said second electric pulsating signal for producing an output signal proportional to the pulses in said second electric pulsating signal.
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9. A detecting apparatus according to claim 9, wherein said wave shaping means includes means for transforming the amplitude of said pulses forming said second electric pulsating signal to a constant peak value.
Specification