Abstract: In a wire bonding head, a transducer block depends from a carriage block via a special link mechanism including a main link member pivotally attached to the carriage block at its one end and to the transducer block at its other end so that the bonding tool tip may move along a vertical and linear path without any lateral displacement as the transducer block moves toward and away from the carriage block. Because the carriage block essentially undergoes a pivotal motion around the pivot on the carriage block, the effective inertia of the transducer block is kept small as compared to the case where a translational motion is caused to the transducer block. The structure according to the present invention is relatively simple and low in cost, and can be made free from plays particularly when the pivots consist of spring pivots using flexures.

Abstract: By detecting the instant of a selected zero-crossing of a received ultrasonic signal rather than relying on the instant the amplitude of that received signal exceeds a predetermined reference amplitude in excess of zero, a transit-time measuring instrument can be realized which is free from the measurement errors normally arising from acoustic signal attenuation in the medium through which it passes.

Abstract: In an ultrasonic fluid flow rate measuring apparatus of the type having a pair of electro-acoustical transducers disposed in respective up-stream and down-stream positions relative a fluid flow and the flow rate is obtained from the difference between the oscillation frequencies of first and second oscillation circuits, the present invention includes an abnormality monitoring circuit responsive to a signal H corresponding to the output of the receiving transducer for providing an output signal W when the signal H exceeds an abnormality monitoring voltage E.sub.1, a trigger circuit for providing an output signal Z to a time difference detection circuit when the signal H exceeds a set voltage E.sub.3 and for providing in response to a signal F an output signal Z to the time difference detection circuit when the signal H exceeds a set voltage E.sub.