부산대학교 도서관

A magnetic circuit having a dual magnet, a speaker and a vibration generating apparatus using the same are provided. The magnetic circuit includes a magnetic gap having a small magnetic loss and an increasing magnetic flux density, in which a uniform distribution of a line of magnetic force can be realized on yoke surfaces facing each other. The speaker includes lower and upper magnets which are spaced so that mutually identical polarities oppose each other; a first yoke integrally having a loop-type circulating circuit portion extended from the lower magnet to the upper magnet and an extension portion which is extended perpendicularly upwards from the lower magnet; a second yoke which connects between the lower and upper magnets and forms a magnetic gap between the second yoke and the extension portion of the first yoke; a coil disposed in the magnetic gap and wound around a bobbin; a frame which is extended from the first yoke; a vibrating diaphragm generating an acoustic sound in correspondence to a drive signal; a damper limiting a vibration range of the bobbin; and a center cap covering the bobbin.