US2538691A

US2538691A - Voice coil for radio loud-speakers

Info

Publication number: US2538691A
Application number: US39472A
Authority: US
Inventors: Richard K Y Kim
Original assignee: Individual
Current assignee: Individual
Priority date: 1948-07-19
Filing date: 1948-07-19
Publication date: 1951-01-16
Anticipated expiration: 1968-01-16

Description

Jan..16, 1951 R. K. Y. KIM 2,538,691

VOICE COIL FOR RADIO LOUD-SPEAKERS Filed July 19, 1948 awe/M1041 Patented Jan. 16, 1951 UNITED STATES JNT DFFICE 1 Claim. 1

This invention relates to loud speakers.

An object of this invention is to provide in a loud speaker of that type embodying a vibratory diaphragm or cone which will practically eliminate inherent distortion and at the same time provide high power handling capacity.

Another object of this invention is to provide in a loud speaker, a vibratory diaphragm or cone wherein the reflected impedance to the line or tubes will be negligible, the frequency response will be improved, and the bass and treble overtones which were heretofore lost or distorted will be made audible and free from distortion.

A further object of this invention is to provide an improved loud speaker wherein the response is linear with input over the entire audio frequency range.

With the above and other objects in view, my invention consists in the arrangement, combination and details of construction disclosed in the drawings and specification, and then more particularly pointed out in the appended claim.

In the drawing:

Figure 1 is a fragmentary vertical section of a loud speaker embodying this invention;

Figure 2 is a fragmentary sectional view taken on the line 22 of Figure 1.

Referring to the drawing, the numeral in designates generally a loud speaker which includes an electro-magnetic member ll having an iron core I2 extending therefrom and projecting loosely into an opening l3 which is formed in a plate I4. A cone or diaphragm i5 is supported by flexible supporting means it from the plate l4 and includes a cylindrical central tubular portion I! projecting loosely into the opening [3 and engaging loosely about the iron core H2.

The tubular member I! has wound thereabout a coil I8 and there is interposed between the coil 18 and the outer surface of the tubular member H a metallic film or coating Hi. This film or coating I 9 is formed of powdered iron and as shown in Figure 1 the coating is extends under the entire length of the coil I8.

A second metallic coating or film 20 is disposed about the outer surface of the coil l8 and also terminates at a point forwardly from the rear end of this coil. The outer coating 2i! is of such thickness that there will be maintained an air gap or space 2| between the coating 2 and the wall of the opening !3. The two coatings I9 and 28' are connected together by a connecting coating 22, and the connected coatings have the effect of creating a high magnetic flux density area adjacent the voice coil i8 for the currents of the voice coil to react on. These coatings also 2 compensate for the difference in magnetic densities with respect to the front and rear, because in uncoated speakers the magnetic densities are usually greater at the rear. The coil I8 is com- I monly known as the voice coil and is disposed in the magnetic fiux generated between the core member l2 and the plate l4. With a voice coil having a partial coating and lining as hereinbefore described, the loud speaker will have a higher degree of efliciency with negligible inherent distortion and the power handling capacity of the speaker will be higher. Furthermore, the reflected impedances will be negligible to the line or tubes and there will be a better or increased frequency response, particularly in the bass overtones and the treble overtones which have heretofore either been lost or distorted.

The term diaphragm as herein set forth and claimed will include both adiaphragm member and a cone which is supported from a flexible support so that the cone will be subjected to the vibrations caused in operation of the loud speaker.

I do not mean to confine myself to the exact details of construction herein disclosed but claim all variations falling within the purview of the appended claim,

What I claim is:

In a loud speaker having an electro-magnetic member, an electro-magnetic core extending therefrom, with an apertured plate about a portion of the core and a diaphragm extending from said plate having a cylindrical central portion projecting into the aperture in said plate about said coil, a voice coil wound about said central portion within said aperture, a powdered iron film interspersed between the inner side of said coil and said central portion, a second powdered iron film surrounding only a portion of the outside of said coil, said portion being of less than one half the length of the coil at the end thereof remote from the electro-magnetic member, and a connecting film between the edges of said first and second film over one end of said coil.

RICHARD K. Y. KIM.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,921,924 Hunter Aug. 8, 1933 1,976,874 Brzeski Oct. 16, 1934 2,164,374 Barker July 4, 1939