US 3293379 A
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Description (OCR text may contain errors)
Dec. 20, 1966 @(jR K 3,293,379
EARPHONE Original Filed Jan. 17. 1961 IN VE NTOR Rudolf y Gb'P/kc United States Patent 3,293,379 EARPHONE Rudolf Giirike, 57c Sternwartestrasse, Vienna, Austria Original application Jan. 17, 1961, Ser. No. 83,289. Divided and this application July 15, 1963, Ser. No. 295,032
Claims priority, application Austria, Jan. 23, 1960, A 496/60 4 Claims. (Cl. 179-1155) This invention relates to an earphone comprising a magnet system, a housing accommodating said magnet system, a diaphragm operable by said magnet system, and an earpiece carried by said housing. This application is a divisional application of the application Serial No. 83,289 filed January 17, 1961, and now abandoned.
The efliciency of such earphones, which convert electrical energy into sound Without requiring additional extraneous energy, is known to depend, inter alia, on the size of the sound emitting element constituted by the diaphragm.
The desire to provide such earphones with magnet systems of light weight and small size in order to reduce the overall weight and apparent size of the earphone was opposed by the previous belief that a decrease in the size of the magnet system necessitated a corresponding decrease in the size of the diaphragm and that the diaphragm diameter should approximately match the diameter of the housing of the magnet system.
The invention provides an earphone comprising a magnet system, an exposed housing distinct from and surrounding said magnet system, a diaphragm at least partly disposed radially outwardly of the periphery of said housing and operatively related to said magnet system, and an envelope comprising an earpiece and carried by said housing, said envelope defining a cavity which accommodates said diaphragm, said envelope being formed with openings which communicate with said cavity on the front and rear sides of said diaphragm.
In a preferred embodiment of the invention, frictional acoustic resistance means may be associated with the openings which communicate with said cavity on the rear side of the diaphragm. It has been found however, that even where such frictional resistance means are not provided, the volume of sound emitted through such rear openings is not disturbing in the vicinity of the earphone.
The frictional resistance means associated with the rear openings may be arranged to be adjustable to vary the frequency response of the earphone.
The envelope is preferably disc-shaped and may consist of one or more parts and its axis extends preferably to the axis of the magnet system or its housing.
Various materials are suitable for making the envelope. For instance, the same may consist of metal or plastics, preferably thermoplastics, such as polystyrene or polymethacrylate resin. An earphone having a particularly small apparent size will be obtained if parts protruding radially outwardly from the housing, including the envelope and the diaphragm, consist of transparent plastics.
An earphone illustrating the invention is shown on the accompanying drawing, in which FIG. 1 is a sectional view taken along a diameter of the earphone and FIG. 2 a fragmentary sectional view illustrating a detail.
With reference to the drawing, a diaphragm 1 is accommodated in a cavity 2 defined by an earpiece envelope consisting of a front plate or earpiece 3 and a rear member or plate 4. The envelope defines a diaphragm cavity for the diaphragm 1 which protrudes radially outwardly from a housing 5, which is smaller in diameter than the diaphragm 1. A magnet system 6 is accommodated in the housing 5. The earpiece 3 is [formed with openings 7, which communicate with the cavity 2 on the front side of .the diaphragm 1. The rear member 4 is formed with openings 8, which communicate with the cavity 2 on the rear side of the diaphragm 1 and which may be covered by a screen 9 constituting a frictional acoustic resistance.
The frequency response of the earphone may be modified by an adjustment of the frictional acoustic resistance 9, e.g., by means of a ring 10, as is shown in FIG. 2.
The ring 10 extends through 360 and has holes, which are in registry with or offset from the holes 8, depending on the adjustment of the ring 10. The adjustment of the effective area and Consequently of the resistance value of a frictional acoustic resistance element such as screen 9 by means of a ring adjoining one side of the resistance element and rotatable relative to another part such as 4 adjoining the other side of the resistance element so that holes through the ring can be moved as desired into and out of registry with holes such as 8 through said other part is described in the Austrian patent specification No. 186,691 issued November 27, 1954, and shown in FIGS. 3 and 4 thereof.
The front and rear members 3 and 4 of the earphone form a peripheral joint 1 and the diaphragm 1 has a rim portion 12 gripped between said members 3 and 4 at the joint.
What I claim is:
1. An earphone comprising a housing having a top opening, an ear piece envelope including a rear plate portion having a substantially central opening with an opening bounding wall peripherally connected to said housing adjacent the top thereof and also having a front plate portion, said piece envelope defining an internal cavity above said housing and extending radially outwardly beyond said housing, a greatly miniaturized electrodynamic drive system in said housing, and a diphragm of substantially normal size disposed in said cavity.
2. An earphone according to claim 1 wherein said rear plate member includes at least one opening defined therethrough having an adjustable frictional resistance in said opening, said opening establishing a connection between the back of said diaphragm and the outside air.
3. An earphone as set forth in claim 1, in which said diaphragm and said envelope consist of transparent material. 4. An earphone as set forth in claim 1, in which said envelope comprises separate front and rear plate members defining a cavity therebetween forming a peripheral joint and said diaphragm having rim portion gripped between said members at said joint.
References Cited by the Examiner UNITED STATES PATENTS 2,506,608 5/1950 McLoad 179179 2,540,498 2/ 1951 Tallman 179180 X FOREIGN PATENTS 186,691 9/1956 Austria.
KATHLEEN H. CLAFF Y, Primary Examiner. F. N CARTEN, Assistant Examiner.