A/s Tomra Systems

Robert G Berntsen

A method, a device and a transducer for dimensional measurement of objects by means of ultrasonics, where the objects are carried past at least an ultrasonic measuring device consisting of a combined transmitter/receiver or separate transmitter/receiver. The reflected ultrasonic signals are used to determine characteristic three-dimensional dimensions of the objects. Said device or devices are arranged either such that the ultrasonic beam or beams therefrom are provided with a reciprocating movement which substantially crosses the direction of movement of the objects or by letting the ultrasonic beam or beams therefrom be stationary. The delay of the reflected signals is used to form a three dimensional image of the object by means of a computer, said image being compared with known images for identification. The ultra sonic measuring device has a narrow, substantially rotation-symmetric radiation diagram. The ultra sonic radiation is directed downwards towards the conveying path through provision of means arranged above and at a distance from the objects to be measured. The transducer uses air as propogation medium and is arranged at a distance from the objects to be dimensionally measured. The transducer consists of an electro-acoustic oscillator arranged coaxially with the centerline of a substantially conical ultrasonic reflector, the angle of aperture of the reflector relative to the center line through the reflector being equal to 45.degree.. The transducer provides ultrasonics having a wavelength in the range of 0.1 to 5 mm, preferably 1.1 to 1.4 mm.

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Asker, Norway

Robert G Berntsen