US1725327A - Sound box for talking machines - Google Patents

Description

Aug. 2o, 1929. H, BlLLER 1,125,327

SOUND BOX FOR TALKING MACHINES Filed June 3, 1924 Figi lll

Patented Aug. 20, 1929.

PATENT OFFICE.

HANS BILLER, OF NUREMBERG, GERMANY.

SOUND BOX FOR TALKING MACHINES.

Application filed .Tune 3, 1924, Serial No.

This invention relates to sound boxes made from thin sheet metal which are not only cheap to manufacture but avoid, owing to the specially simple and advantageous construction, the prejudicial extraneous noises which occur in the cheap toy sound boxes of commonly used type. According to the invention the stylus bar is fixed on a ring-shaped plate of comparatively heavy weight, whereby an easy and clear sound transmission from the needle to the diaphragm is ensured. A further essential characteristic feature of the invention consists in that this heavy plate covers the box for its largest part of the side facing the needle, whereby the diaphragm is protected as well as possible against being damaged from the outside.

An embodiment of t-he invention is shown, by way of example, on the accompanying drawing, in which:

Fig. l shows in front elevation the sound box with the disk support.

Fig. 2 is a horizontal section through the middle of the sound box.

The body or casing 1 of the sound box is pressed or stamped from comparatively thin sheet metal. The diaphragm 2 is insulated from the casing l by paper or rubber rings 8. A ring-shaped strong plate 3 of comparatively great mass serves as cover for the casing l and protects the diaphragm against being damaged from the outside. On this heavy plate 3 the stylus bar 4 is rigidly 717,508, and in Germany March 1, 1924.

fixed, said bar serving to transmit its vibrations to the diaphragm 2. When the needle 5 has been fixed in the mounting 6 with the aid of the clamping screw 7 and when oscillations are communicated to this needle by the grooved disk 9, the oscillations of the needle are transmitted owing to the great moment of inertia of plate 3 almost entirely upon the stylus bar 4 and thence ro the diaphragm 2 which is mounted as loosely as consistent with proper reproduction. No disturbing oscillations are transmitted to the casing l owing to the fact that the mounting 6 of the needle is securely fixed on the heavy plate 3, this plate being not sensitive. The stylus bar 4 can thus transmit the oscillations of the needle 5 upon the diaphragm 2 almost entirely and wit-hout prejudicial secondary actions and the secondary noises which are usually due to the individual oscillations of the casing are avoided.

In a sound box for a talking machine a circular box body pressed from one piece of sheet metal, a heavy ring-shaped inertia plate in said casing, a stylus bar with stylus rigidly fixed on said inertia plate, and a diaphragm underneath and partly covered by said inertia plate which is of such great mass that the transmission of vibrations of said stylus bar upon said inertia plate is prevented.

In testimony whereof I affix my signature.

HANS BILLER.

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