GB1122698A - Loudspeaker with asymmetrically shaped diaphragm - Google Patents

Abstract

1,122,698. Diaphragms; moving coil loudspeakers. NIPPON GAKKI SEIZO K.K. 10 Oct., 1966 [3 May, 1966], No. 45103/66. Heading H4J. A loudspeaker comprises a diaphragm of planar form clamped to a frame, the diaphragm being of an asymmetrical shape and driven at its geometric centre. A moving coil loudspeaker (Fig. 6B) has a diaphragm 11 produced by cutting off a rightangled triangle from one end of a rectangle. Alternatively, the cut may be a curvilinear line extending from one side to the other of the rectangle (Fig. 9, not shown), or merely cutting off a corner of the rectangle (Fig. 11, not shown). Alternatively a right-angled triangle may be cut from a lengthwise side of the rectangle (Fig. 10, not shown). The diaphragm may be a right-angled triangle having no two sides equal (Fig. 12, not shown). Alternatively the diaphragm is a trapezoid with unequal sides (Figs. 13, 14, not shown) or a polygon with unequal sides. In another embodiment (Fig. 15, not shown) the diaphragm is generally elliptical having a concave part formed by a reversal of curvature. In a further embodiment (Fig. 16) the diaphragm is basically an ellipse but has three concave parts formed by reversals of curvature. The diaphragm is preferably of foamed polystyrene. The asymmetric shape suppresses the establishment of third order vibration modes.