US1763876A

US1763876A - Acoustic diaphragm and mounting

Info

Publication number: US1763876A
Application number: US79165A
Authority: US
Inventors: Baldwin Nathaniel
Original assignee: Individual
Current assignee: Individual
Priority date: 1926-01-04
Filing date: 1926-01-04
Publication date: 1930-06-17
Anticipated expiration: 1947-06-17

Description

June 17, 1930. wm 1,763,876

ACOUSTIC DIAPHRAGM AND MOUNTING Filed Jan. 4, 1926 W INVENTOR Patented June 17, 1930 UNITED STATES NATHANIEL BALDWIN, OF EAST MILL CREEK, UTAH ACOUSTIC DIAPHRAGM AND MOUNTING Application filed January 4, 1926. Serial No. 79,165.

The present invention appertains to acoustic diaphragms and particularly to that class in which large diaphragms are used without horns for loud speakers.

The principal objects of this inventioriare to provide an improved diaphragm of the class commonly made in the form of a cone, to provide an improved housing for the diaphragm, and to provide an improved means of mounting said diaphragm.

I attain these and other objects by the mechanism illustrated in the accompanying drawing in which Fig. 1 is a vertical section, showing the several features, and Fig. 2 is a front elevation showing the diaphragm and part of the mechanism used in mounting the same.

In the figures of the drawing numeral 1 designates the housing which may be made preferably in the form of a cylinder. N11.- meral 2 designates a ring which is secured to the inner surface of the housing 1, and at its inner circumference is provided with a; projecting flange 3, which forms a seat for the diaphragm. The diaphragm, preferably made of paper or other like material, consists of an inner portion 4 which is reenforced preferably by being formed into a special shape, such as the cone shape shown in the figure, an outer plain portion 5 which permits the necessary movement of the central portion 4, and an edge portion 6 bent at right angles to the plain portion 5 and set into a reenforcing rim 7, made of a folded strip of metal or other suitable material. A short fold in the edge portion 6 of the diaphragm will enable the rim 7 to be clamped on with security. The rim 7 is somewhat larger in diameter than the flange 3 and when the diaphragm is placed against the flange 3 and force is applied to the rim 7 to press the diaphragm against the flange, the diaphragm will e put under tension, according to the force applied to the rim.

A suitable force against the rim 7, and uniformly distributed around it is obtained ,by means of an expansible ring 8, preferably a compressed splral spring which presses against an inclined surface 9, on one side of an annular groove formed in the inner wall of the housing 1, and against said rim. The housing may be conveniently made of sheet metal, in which case the groove will consist of an annular head in the material. If a spiral spring or some equivalent means is used as the expansible ring 8, it will adjust itself to the expansions or contractions of the diaphragm and maintain a proper tension of the same.

This diaphragm may be used for any of the purposes for which diaphragm's are used, to receive sound or to reproduce it; but as here illustrated it is electrically operated and serves as a loud speaker. The apex of the cone is connected by a rod or cord 10 to an armature 11, which is secured to one pole of the permanent magnet 12. A polepiece 13 surrounded by the actuating coil 14 is connected to the other pole of the permanent magnet 12 and approaches the armature 11. Themagnet 12 is mounted within the housing 1 by means of a screw and spacing block 15 as shown.

A convenient base for the instrument is formed by joining two pieces of pressed or spun

metal

16 and 17 and connecting them to the housing as illustrated.

I claim:

1. A diaphragm with-cone shaped inner portion and substantially plain outer portion with folded edge and a reenforcing rim consisting of a band folded over the folded edge of the outer portion.

2. A diaphragm with reenforcing rim, a housing for said diaphragm, an annular seat for said diaphragm secured to said housing,

an annular inclined surface in said housing, 1

and an expansible ring pressing against said inclined surface and against said rim and adapted to put tension on said diaphragm by pressing it against said seat.

3. A diaphragm with cone-shaped inner portion and substantially plain outer portion, a reenforcing rim consisting of a band folded over the edge of the outer portion, a cylindrical housing, for said diaphragm, an annular seat for said diaphragm secured to said housing, an annular inclined surface in said housing, and a compressed annular spiral spring pressing against said inclined surface and against said rim and adapted to put tension on said diaphragm by pressing it against said seat.

4:. In an acoustic device, a diaphragm having a folded periphery, a housing 'within which said diaphragm is mounted, a reinforcing rim folded over the folded periphery of said diaphragm, a seat for said diaphragm bearing thereagainst radially inwardly of said folded periphery and tension, means acting against the folded edge of said reinforcing rim. v

5. In an acoustic device, a diaphra m having a folded periphery, a housing or said diaphragm, a seat within said housing bearing against said diaphragm radially inwardly of said periphery, a member under compressive stress bearing against the said reinforcing rim, and a sloping seat within which said stressed member is seated, the said seat sloping toward said reinforcing rim.

NATHANIEL BALDWIN.