US1809571A - Loud speaker - Google Patents

Description

June 9, 1931. H. J. ROUND 1,809,571

1.6111) SPEAKER Filed Nov. 11, 1924 INVENTOR ESNRY J. ROUND Q4 ri%% 'ATTORN EY Patented June 9, 1931 UNITED STATES, PATENT orrlcs HENRY JOSEPH ROUND, OF LONDON, ENGLAND, ASSIGNOR TO RADIO CORPORATION OF AMERICA, A CORPORATION OF DELAWARE LOUD SPEAKER Application filed November 11,1924, Serial No. 749,117, and in Great Britain November 19, 1923.

The object of this invention is to provide an improved loud speaker.

According to this invention I mount upon an umbrella-like structure consisting of radial ribs and stretchers a covering of paper, varnished silk or the like, and I provide means whereby the speech currents or the like which are to be converted into sound waves produce a longitudinal movement of the stick so that the covering is vibrated by the currents.

The invention is illustrated by the accompanying drawings in which Figure 1 is a diagrammatic illustration of one form of my invention;

Figures 2 and 3 show respectively, a sectional view and a plan view of a modification ofmy invention; and

Figure 4 is a diagrammatic illustration of still another modification of my invention.

In Figure 1, A is a stick or rod which passes through the runner B and has attached to it a plurality of spaced ribs C which are covered by a membrane, for example paper, and are connected b-y stretchers D to the runner B in the manner of an umbrella or parasol. The runner is pinned or secured to the stick after the diaphragm is stretched. The stick A carries the armature E of an electromagnet F through the coil of which speech currents or the like can be led. The currents in the coil of the magnet will cause the stick to move to and fro. This vibration will be carried through the stick and the stretchers to the ribs and from these ribs on to the membrane.

Preferably the covering is of such a size that it cannot be opened to such an extent as to make it flat, thus enabling the surface to be well stretched.

As an alternative the stick may act as the core of a solenoid through which the currents are passed.

The motion of the stick may, however, be obtained in various other ways, electrostatically, electromagnetically or by a magnetostriction device. a

Inplace of the stretchers being on the concave side they may be placed on the convex of the structure, the more so the lower tones predominate, and therefore that with a large structure of this kind it is preferable to employ a smaller one to prevent the loss of higher tones. Both membranes may be mounted on the same rod or stick. Figure 4 shows such an arrangement where both the large membrane and the small membrane are mounted on the same rod.

Such an umbrella-like arrangement may also be employed to produce sound when the movements of the stick and stretchers are obtained mechanically instead of electrically or magnetically.

For instance, a needle inserted in the stick at right angles thereto may beactuated by a gramophone record.

In some cases I may dispense with the stretchers and use a flat structure, with stretched wires as ribs connecting a fixed rim to a centre piece which takes the place of the stick and acts as the armature of an electromagnet through the coils of which the currentsare passed.

I Such an arrangement is illustrated in Fig ures 2 and 3, Figure 2 being a section and Figure 3 a plan.

The ribs C are connected each at one end to afixed rim G and at the other end to the armature E of the magnet F, varnished paper or silk being stuck on to the ribs.

Having described by invention what I claim is 1. In combination, a plurality of spaced strips, a membrane covering the strips, stretchers attached to the strips and means for actuatin the structure to re )roduce sound.

2. In a loud speaker, a plurality of ribs, a membrai'ie stretched upon said ribs, lJl'tlCQrv' tor reinforcing the ribs and means for reciprocating the assemblage formed by the ribs braces and memlnanc in a line 1 erpendicnlar to the general plane oi? the membrane.

3. In a loud speaker, a concave shaped membrane, ribs for spreading the membrane, stretchers :lior teusioning the ribs and means for vibrating the membrane to reproduce sound.

4. In a loud speaker, a tympanum having a plurality of elements attached together, the elements each consisting of a membrane stretched upon stretching ribs, braces for re inforcing the ribs and means for reciprocating said tympanum in a line perpendicular to the general plane of the membrane.

5. In a loud speaker, a series of intersecting ribs, a reciprocable element terminated at the center of said series of intersecting ribs, braces attached to the reciprocable element and to the ribs, a membrane fitted over the ribs, and means for reciprocating the reciprocable member.

6. A loud speaker comprising a plurality of intersecting ribs, a member normal to said. ribs at their point of intersection, a brace attached to each rib and to said normal member for retaining said ribs in fixed position, a membrane fitted over said ribs, a drivii'lg member fastened to said normal member and an actuating means for operating said driving member.

7. A loud speaker according to claim 6 in which said ribs are bowed and said braces are attached to said ribs at approximately their mid-points.

8. A loudspeaker comprising an actuating means, a member reciprocated by said actuating means, a large diaphragm member attached to said reciprocating member and a small. diaphragm member also attached to said reciprocating member, said large diaphragm being located between said small diaphragm and said actuating means.

9. A loudspeaker comprising an actuating means including a movable member, a second member connected at one end to said movable member, and a plurality of sound wave pro ducing members connected to said second member.

10. A loudspeaker according to claim 9 in which said plurality of sound wave producing members are difl'erent sizes.

11. A loudspeaker comprising an actuating means, a member attached to a part of said actuating means to bereciprocated thereby, and

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