JPS5091544

sides of the membrane, and the magnetic poles 8+9 and 10. Electrodynamic lithographic speakers are also known in which 11 project parallel to opposite sides of the diaphragm 5 and each folded conductor 12 of the diaphragm 5 is provided with 119 to extend and contract the diaphragm 5, but the poles 8%9 and 10y11 prevent the emission of sound waves and have the disadvantage of increasing thickness. The present invention eliminates the above-mentioned disadvantages by arranging a plurality of magnets transversely (so as to provide a folded vibrating membrane in the magnetic field produced thereby. The following is the following: ttcQl#a? 1A The embodiment shown in FIGS. 3 and 5 will be described in detail. Reference numeral 16 denotes a columnar tetragonal ferrite magnet, which is arranged at a plurality of predetermined intervals (y4 mm) so that the same magnetic poles are arranged side by side, and a support rod 14 is fixed at the same magnetic pole between the magnets 15, and a vibrating film 15(2)1 such as a very thin polyester film is alternately folded and stretched over the magnet 13 and the support rod 14. Then, conductors 16 (f5Vα2sw) are attached to the respective surfaces of the folded vibrating film 15 by bonding, and the conductive wires are wired so that the directions of currents flowing through adjacent conductors are opposite to each other. Since the present invention is so constructed that when a sound current is applied to the conductors 16, each conductor 16 generates a force in the direction of the arrangement plane of the magnets 16, and the adjacent conductors receive a force in the opposite direction, the vibration 11N5 vibrates in the same direction as the arrangement plane of the magnets, the volume of each folded vms of the lift 115 increases or decreases, and the air is pushed out or taught to generate a sound wave in a direction perpendicular to the arrangement plane of the magnets. That is, each of the vmW 6 minutes is a narrow band-shaped sound source, and the sound sources are combined to form a surface sound source that emits sound waves in the same phase. By narrowing the gap with respect to the depth of the folded folds, a large volume velocity can be obtained with respect to the displacement of a small vibrating membrane, and since the effective vibrating area is large in a roof, the efficiency is good, the distortion can be reduced, since the volume of each V-shaped portion is small, the divided vibration does not occur from a low frequency to a high frequency, and since the vibration is divided (3)), the vibration is easily controlled with a uniform tension It has a quiet practical effect.

67 It is to be noted that the conductors 16 may be attached to each 1 of the folded vibrating membranes and the impedance of the amplifier may be altered by multiple folds between at least 1 pair of magnets 9. The orientation characteristics can also be controlled by arranging the magnets in a cylindrical 06 plane, for example.

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