JPS6474898A - Speaker - Google Patents

Abstract

PURPOSE:To decrease the characteristic degradation of a sound to be irradiated with a front surface by causing the diameter of a magnetic circuit, which positions in a front surface side, to be smaller than the diameter of the magnetic circuit of a rear surface side when a diaphragm, which is inserted between first and second magnetic circuits, is pushble-driven and causing the current values and line lengths of these voice coils to be different. CONSTITUTION:The both edges of a plane diaphragm 10 are inserted between second and first frames 18 and 8 which are mutually faced with an elastic edge 9 between them. Then, to the central opening of the frame 18, a permanent magnet 12 to constitute a front surface side second magnetic circuit 11 and a second coil bobbin 15 to pass through this magnet are inserted and a sub-corn 17, to which the bobbin 15 is fitted, is fixed to the surrounding part of the diaphragm 10. A rear surface side first magnetic circuit 1 of the same construction is provided also to the frame 8 side, however, at such a time, the dimension of the second and first magnetic circuits is made different. Namely, an outer diameter D2 of the second circuit 11 is remarkably smaller than an outer diameter D1 of the first circuit 1 and the current of an inner coil 5a of respective voice coils 15a and 5a is increased or the coil line length is made long.