Passive Radiator For Use In A Bass Reflex Loudspeaker System

Abstract

A passive radiator formed of a drone cone for use in a bass reflex loudspeaker system wherein a centering device for suspending the central part of the drone cone within a basket frame is made of elastic wire members.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a passive radiator comprising a drone cone for use in a bass reflex loudspeaker system.

There is known a bass reflex type loudspeaker system provided with a drone cone to broaden the range of reproduced sound frequencies so as to include low frequencies. A passive radiator constituted by such a drone cone heretofore consisted of a centering spider prepared by thermally molding resin-impregnated fabric as a centering device for supporting the drone cone. Since the drone cone is generally required to have a low resonance frequency, it should have a large mass and the centering spider should also have great compliance. However, such type of passive radiator has the drawbacks that there most likely occurs permanent displacement due to the qualitative nature of a fabric spider, there is not obtained a sufficient centering capacity in the direction in which the drone cone vibrates, and it is difficult to maintain the linearity of the drone cone vibrations over a broad range of amplitude, thus leading to distortion of the reproduced sounds. Furthermore, such fabric spider has a low moisture resistance due to its qualitative nature and presents prominent changes with time in physical properties, so that it is not preferably adapted for practical application.

It is accordingly the object of the present invention to provide a passive radiator which exhibits reduced distortion of the produced sounds and which is characterized by excellent moisture resistance and durability.

SUMMARY OF THE INVENTION

According to the present invention, the centering device for holding the central part of a drone cone constituting a passive radiator is made of elastic wire members, so that it is little subject to permanent displacement and has excellent moisture proof and durability characteristics. Therefore, the centering device of the present invention enables the drone cone to be better centered in the direction in which it vibrates and also said vibrations to have a linearity over a broader range of amplitude than has been possible with the prior art, thus noticeably minimizing distortion of the reproduced sounds.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a side view, partly in section, of a passive radiator according to an embodiment of the present invention; and

FIG. 2 is a back view of the embodiment of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

To the front part 12 of a basket-type frame 11 is fitted, as illustrated in FIGS. 1 and 2, the peripheral edge of a drone cone 14 assuming a conical shape by means of an edge suspension 15. On the central top of the drone cone 14 is fixed a disc 16. To each of three points, for example, on the fixed disc 16 is connected one end of three elastic wire members 17, 17' and 17" respectively. Said members 17, 17' and 17" consist of, for example, piano wires fabricated in zigzag form. The other ends thereof are attached to the inside of the rear part 13 of the basket frame 11 in a radial arrangement at a peripheral spacing of substantially 120.degree., thereby forming a centering device for holding the drone cone 14 while imparting a proper degree of elasticity thereto. The fixed disc 16 has an adequate weight and plays the role of increasing the mass of the cone 14 for further reduction of its lowest resonance frequency, should the mass of the cone 14 be found insufficient.

The compliance of the centering device according to the embodiment of the present invention formed of three piano wires is determined to a desired extent, as in the case of the prior art passive radiator, in consideration of the required lowest resonance frequency of the passive radiator itself, the mass of the drone cone 14 and fixed disc 16, the compliance of the edge suspension 15 and other factors of the loudspeaker system.

Claims

What we claim is:

1. A passive radiator for use in a bass reflex type loudspeaker system comprising a basket frame, a cone whose peripheral edge is suspended from the basket frame, and a centering device including elastic wire members for suspending the central part of the cone within the basket frame.

2. The passive radiator according to claim 1 wherein the centering device includes a plurality of piano wires connected at one end to the central part of the cone and at the other end to the basket frame.

3. The passive radiator according to claim 2 wherein the piano wires are fabricated in zigzag form.

4. The passive radiator according to claim 3 wherein the zigzag form piano wires are radially disposed at a peripheral spacing of substantially 120.degree..

5. The passive radiator according to claim 1 including a fixed disc connected to the central top portion of the drone cone, the elastic wire members being connected to the fixed disc for suspending said central part of the cone within the basket frame.

6. The passive radiator according to claim 5 wherein the elastic wire members are connected at one end to the fixed disc and at the other end to the basket frame.

7. The passive radiator according to claim 6 wherein the elastic wires are radially disposed and are peripherally spaced around the fixed disc at peripheral spacings of substantially 120.degree..