US1355552A - Diaphragm and process of making same - Google Patents

Description

W. FRICK.

DIAPHRAGM AND PROCESS OF MAKING SAME. APPLICATION FILED 00130. 1919.

1,355,552. Patented Oct. 12, 1920.

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N 3 Am 10 1a 1a UNITED STATES PATENT OFFICE WILLIAM ERICK, OF NEW YORK, N. Y., ASSIGNOR TO CLIFF MANUFACTURHQ'G- WORKS INC., 01 NEW YORK, N. Y., A CORPORATION OF NEW YORK.

DIAPHRAGM AND PROCESS OF MAKING SAME.

Specification of Letters Patent.

Patented Oct. 12, 1920.

T 0 all whom it may concern:

Be it known that I, VVILLIAM FRICK, a citizen of the United States, and resident of the city of New York, in the county of Queens and State of New York, have invented certain new and useful Improvements n Diaphragms and Processes of Making the Same, of which the following is a specification.

This invention relates 'to diaphragms for sound recording, reproducing and transmltting instruments, and particularly to diaphragms composed of diflerent materials and to the process of preparing the same.

It is the object of this invention to provide a diaphragm which is sensitive enough to follow the higher frequencies of overtones with utmost accuracy, without producing any vibrations of its own, not transmitted thereto by the stylus lever.

It is also an object of this invention to provide a diaphragm which is a compact unit, simple in construction and which remains unaffected by atmospheric influences.

It is another object of this invention to provide a diaphragm whose annular sections are as nearly as possible of the same fiexural resistance.

With these objects in view the invention consists in certain novel combinations of parts and substances hereinafter described and particularly pointed out in the claims.

In the accompanying drawings which are made a part of these specifications, Figure I is an'enlarged vertical section through a reproducer provided with my 1mproved diaphragm, taken on the line A-A of Fig. H.

Fig. 11 is a plan view of a reproducer, includinga diaphragm embodying the invention.

Similar characters of reference indicate corresponding parts throughout the various views.

The diaphragm mounting shown in the accompanying drawings is the subject matter of a separate .and copending application for Letters Patent, in which I have pointed out that by numerous experiments with diaphragms of various forms and materials I have evolved the theory that a diaphragm for phonographs should be held at its rim and to the stylus-lever as rigid as mechanical means can make this possible. A dia phragm of uniform thickness deflects considerably more in its central portion than at its rim, and impulses of quick succession originating at the center will spread as waves toward the rim, and being of a different frequency from the main sound wave, they will impair the correct reproduction of the latter. Reinforcing plates in the central part of a thin diaphragm leave an annular ring near the rim of the diaphragm which is practically its only deflecting part and they do not permit the whole diaphragm to take a uniform part in the sound repro-' duction. Furthermore this ring is generally subject to atmospheric influences which impair the sound-reproducing qualities of the diaphragm.

I have therefore constructed my diaphragm to be practically of uniform resistance to fiexure at all of its annular sections and use a combination of materials, best suited for this purpose on account of their flexural and sound transmitting qualities, and specially prepared to remain unaffected by atmospheric conditions.

With these ideas in view I have constructed my diaphragm 1 as follows: 1 is a disk having the shape of a very fiat cone, or double cone, made of fibrous material, as thin paper, (matrix paper) pressed into shape under application of heat, or of pasteboard, but preferably of soft wood, which 1 found to have the best sound producing qualities. This disk is of such size that its outer diameter is equal to that of the opening 3 of the reproducer holding ring 8, and is made as thin as possible at itscircumference, to form a knife edge. At its axis, which is occupied by the stylus-lever-screw 1 the disk is of considerable thickness and affords thereby a long grip for this screw. This disk 1 is immersed into a solution of glue, preferably fish glue or liquid cement, containing about forty per cent. of formalin and when a sufiicient quantity of this solution is absorbed by the disk, it is interposed between two sheets of thin leather, l and 1 of larger diameter than the disk 1 and the same solution of cement is used to join the two sheets of leather on their border, where they bear against each other and are held by the ledge 2 and ring 3 of the reproducer casing. The diaphragm so made, is then pressed in a suitable mold to the desired shape until the cement has set, both outer faces of the diaphragm on 1 and 1 are then treated with a varnish solution of shellac in alcoholor a bakelite varnish and then dried.

In this manner a very light diaphragm is produced, the annular sections of which are of practically uniform resistance to fiexure.

The special cement permeates the fibrous material as well as the leather, filling the is provided as a further protection for the leather coverings against atmospheric influences.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A diaphragm for phonographs and the like whose unsupported part forms a triangle in radial section, consisting of a core of fibrous material treated in its outer fibers with a hardening substance, and covered on both faces with a layer of flexible material adhering to said core.

2. A diaphragm for phonographs and the like consisting of a core of fibrous material forming a disk of substantial thickness at its center and gradually sloping to a knife edge at its circumference and an airproof sheeting covering both faces of said disk.

3. A diaphragm for phonographs and the like consisting of a core of porous material of conical-shape, a waterproof cement filling faces of said core, rigidly held thereon, andv a waterproof coating covering said sheet material on either side.

4. The method of preparing a diaphragm for phonographs or the like which consists in treating a disk of fibrous texture with a waterproof cement until a portion of said cement is absorbed by said disk, covering both faces of said disk with sheets of waterproofed fibrousmaterial and allowing the whole diaphragm to harden under pressure.

5. The method of preparing a diaphragm for phonographs and the like, which consists of compressing a stack of thin paper into a disk under application of heat, immersing said disk into a cement, comtaining formalin until a portion of said cement is absorbed by said disk; covering both faces of said disk with sheets of fibrous texture adhering to said disk and allowing the whole diaphragm to harden under pressure.

6. The method of preparing a diaphragm for phonographs and the like, which con-- sists in treating a disk of fibrous texture with a cement until a portion of said cement is absorbed by said disk, covering both faces of said disk with sheets of fibrous texture, allowing said cement to setunder pressure and applying a coating of waterproofing varnish to the faces ofsaid diaphragm.

WILLIAM FRICK'.

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