FR2818487A1 - Loudspeaker construction having three loudspeaker motors plane placed with moving coils relayed mechanically rigid/light membranes. - Google Patents

Abstract

The electromagnetic loudspeaker has three loudspeaker motors (4) placed in a plane (5). The moving coils (1) are relayed mechanically to a plane membrane (2) made of a rigid and light material. The motors set variable distances to remove resonance.

Description

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Most of the loudspeakers used in electroacoustics are of the electromagnetic type. They consist of a moving coil circulating in a magnetic field and a usually conical horn mechanically connected to the moving coil.

Such loudspeakers have the disadvantage of being able to function properly only in a reduced frequency range because the conical horn attached to the voice coil has a high mechanical inertia and therefore lends itself poorly to the transmission of high frequencies. Conversely, if a loudspeaker whose membrane is of small diameter, of the order of magnitude of the voice coil, is produced in order to produce a low inertia assembly, the loudspeaker will be ill-suited to the retransmission of low frequencies.

In addition, each pavilion dimension implies one or more resonant frequency which results in a privileged reproduction of said frequency.

Attempts have been made to equip a single pavilion with several electromagnetic motors.

The company SONY based on the work of Mr. TOSHIO Hayasaka proposed a model using 4 motors arranged on the diagonals of a square membrane.

Although such a model has advantages over traditional loudspeakers, it does not eliminate the resonant frequencies linked to the diagonal separating 2 motors located in opposite corners, nor does it sufficiently eliminate the inertia of the membrane.

The present invention proposes to considerably improve the range of frequencies transmitted by the same loudspeaker, both in low frequencies and

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 in high frequencies. It essentially consists in connecting a flat, light and rigid membrane to several motors arranged so that the distances separating 2 moving coils are such that the inertia of the membrane becomes small compared to that of the moving coil. According to another characteristic of the invention, it is advantageous to have the different motors actuating the loudspeaker membrane at different distances so as to attenuate if not to eliminate a preferential frequency corresponding to the resonance frequency of the membrane.

According to another characteristic of the invention, the periphery of the membrane is not, unlike conventional loudspeakers, mechanically attached to the mechanical structure, called a bowl, which supports all of the elements of the loudspeaker. Indeed, if at least 3 electromagnetic loudspeaker motors are arranged on a plane and the moving coils are themselves connected to another plane, the centering system, called spider, of each of the moving coils is sufficient to force all the moving coils to move parallel and perpendicular to the surface of the plane of which they are integral.

By way of nonlimiting example, we will describe the production of a loudspeaker according to the invention: five motors (4) are arranged on a metallic plane (5). The moving coils (1) individually centered by a so-called spider diaphragm (3) are mechanically connected to a flat membrane (2). In the example described, the 5 motors (4) are intentionally placed at different intervals so as to attenuate the frequencies of

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 resonance linked to the distance separating 2 successive motors.

This provision which is not limiting can advantageously be used.

One of the coils of such a loudspeaker can be used as a voltage source intended to electrically correct the residual resonant frequencies by electrical feedback applied to the input of the amplifier supplying said loudspeaker.

Claims (4)

 1) Electromagnetic loudspeaker characterized by at least 3 loudspeaker motors (4) arranged on a plane (5), the moving coils (1) of which are mechanically connected to a flat membrane (2) made of a rigid material and lightweight. 2) Loudspeaker according to claim 1 characterized in that the space separating 2 successive motors (4) is not the same. 3) Loudspeaker according to claim 1 characterized by the mechanical connection of the membrane (2) to only the moving coils (1). 4) Loudspeaker according to claim 1 characterized by the use of the voltage appearing on one of the moving coils (1) to correct against electrical reaction the mechanical resonances of the loudspeaker.