Abstract: An opening type bone conduction earphone which eliminates headband and has a compact and simple structure comprising a magnetic body, which has an aeration hole, which is able to communicate with the outside world when wearing, at the center part of the axial direction, at least one or more dampers provided at the outer circumference of the magnetic body, and a coil bobbin, which is provided at the outer circumference of the magnetic body, accommodates the damper within a trunk part, and in which a coil is wound at the outer circumference of the trunk part, is provided.

Abstract: A new and improved electronic circuit and a method of producing the same is provided in which at least one electronic element is ultrasonically welded to a printed circuit board to create the electronic circuit. Proper alignment between terminals of a conductive circuit pattern on the circuit board and terminal units on the connecting surface of the electronic element is ensured by a variety of techniques: (i) small protuberances on the terminal units, (ii) raised sections on the bottom surface of the terminal units placed to engage indented portions of the board, and (iii) corresponding posts (on the electronic elements) and holes (formed on the circuit board). The ultrasonic welding of the element to the printed circuit board is typically conducted at a frequency range between 25-30 megahertz which produces a vibration which grinds the terminal units of the electronic element to the terminals of the circuit pattern while also welding the element and circuit board together.