US1778400A - Telephone transmitter - Google Patents

Description

Oct. 14, 1930. c. pococ ET AL TELEPHONE TRANSMITTER Filed March 6, 1929 L. C. POCOCK INVEN 1?. BLACKBURN A 7' TORNEY Patented Oct. 14, 1930 UNITED STATES PATENT OFFICE 1 LYNDALL C. POCOCK AND REGINALD BLACKBURN, OF LONDON, ENGLAND, ASSIGNORS TO WESTERN ELECTRIC COMPANY, INCORPORATED, OF NEW YORK, N. 'Y., A GOR- PORATION OF NEW YORK TELEPHONE TRANSMITTER Application filed March 6, 1929, Serial No. 344,774, and in Great Britain July 28, 1928, V

This invention relates to telephone transmitters and more particularly to transmitter mouthpieces of the hygienic type.

An object of the invention is to improve the acoustic properties of mouthpieces for telephone transmitters.

Various attempts have been made to produce transmitter mouthpieces of hygienic pattern which comprise a smooth outer surface which can be easily kept clean. To this end, spherical and other shapes of mouthpieces have been provided, slots or other shaped passages being formed in the shell for the purpose of allowing sound waves to enter.

It has been found, however, that owing to the relatively large hollow space in the interior of such mouthpieces they have very poor acoustic properties. vention therefore aims to provide an im proved form of such hygienic type of mouthpiece in which the above disadvantages are overcome.

In accordance with the present invention a substantially solid mouthpiece having a smooth outer surface is provided with one or more sound passages therein communicating with a passage which is arranged to direct the sound waves onto the transmitter diaphragm. Preferably the first mentioned passages are in the form of slots which communicate with a cylindrical central passage transverse to the slots. The said passages with the transmitter are preferably proportioned in such a manner as to form a mechanical filter.

According to another feature of the invention means is provided to seal the jointbetween the central passage in the mouthpiece and the transmitter proper.

Examples according to the invention are illustrated in the accompanying drawing in which Fig. 1 is a sectional diagram illus trating a portion of a handset with a spherical mouthpiece. Fig. 2 is a sectional diagram illustrating a modified form of mouthpiece. Fig. 3 is a face projection of the mouthpiece shown in Fig. 2, and Fig. 4 is a transverse section showing the arrangement of the slots.

It will be seen from the drawing that the The present in-' mouthpiece according to this invention com-= prises a substantially solid dome-shaped moulding 1, having a smooth outer surface broken only by the slots 2 which commimicate with a central passage 3 which is arranged to direct the sound waves from the slots onto the transmitter diaphragm.

The cross-sectional area of the slots 2 is arranged to be substantially equal to the cross-sectional area of the central passage 3 and in order that the junction betweenthe said slots and passage may be effective without any throttling action it will be noted that the outer edges of these slots are carried down and converge into the central passage in a stepped formation. I

The central passage preferably makes a sound tight joint with the transmitter proper and for this purpose suitable washers may be provided on the lip 4. The central passage 8 may be cylindrical or slightly conical the transmitter 9, the floating diaphragm 10 being arranged behind the plate and form-. ing the driving member for the granules in the chamber 11.

It will be seen that with the construction herein described a mouthpiece of very simple form and one which may be readily moulded, is obtained. Moreover, the mouthpiece possesses considerable strength and is of i1nproved acoustic properties owing to the absence of large hollow spaces within it.

What is claimed is:

1. A transmitter comprising a casing, a diaphragm within said casing, and a substantially solid dome-like mouthpiece attached to said casing, said mouthpiece having long narrow sound passages therein communicating with a central cylindrlcal passage arranged to direct sound waves onto said dlaphragm.

. 2. A transmitter comprising a casing, a diaphragm Within said casing, and a substantially solid dome-like mouthpiece attached 7 to said casing, said mouthpiece having sound 5 passagesthereincommunicating with 'a central passage, said sound passages being -in theform of slots which enter the central pasisage substantially at right angles. A transmitter according to claim 2 in 10 which the cross-sectional area of the slots is substantially equal to the cross-sectional area of the central passage, the junction between I v said slots and passage being efiected Without ammusgr LA transmitter comprising a casing, a d iaap'hragm Within said casing, a substantially solid dome-like mouthpiece attached to said I easing and having a central passage therein, and aise aling member between 'said in'outhpiece and said diaphragm adjacent said central passage h 5- 5,;A tifansinitter comprising a easing, a ;l-i'aphra-gm Within said casing, a substantiallysolid dome-like mouthpiece attached to. said casing having a central passage therein, an iapertured plate between said diaphragm and mouthpiece, and a sealing member car- Tied by saidfmouthpieceand engaging said pe pre m fiei i '6. A transmitter comprising a easing, a diaphragm within said casing, a substantially sOliddOIfie-like mouthpiece attached to said casin'gjsaid mouthpiece having sound pas- E'sage's therein communicating with a central 3%, :pas sagegand a hollow gauze lining in'said central passage oii said mouthpiece.

lo- A transmittercomprising a casing, a diaphragm yv'i'thin said casing, a substantially fsolid dorne-like mouthpiece attached to said 4n casing and having sound passages therein communicating with a central p'assage,."aiid .a gauze lining in said centr al passage, said flijning having an outwardly extending rim held between said mouthpiece and "said dia- EPhI' g i-HL. .Q 1 P 8 A transmittercomprising a casing, 'a diaghragiri jwithin said casing,iasubstantially o "solid dome-like mouthpiece attachedto said casing haying a central passage thereinfan m: apertured plate between said diaphragm and uth'piece, and Y a sealing ring clamped besaid meuthpiece and said ap'erture'd plate. i I j 19., Atransmitter comprising; a casing, a

diaphragm yvithin'said casing, a substantially solid dome like mouthpiece attached to said casing, said mouthpiece having slits therein 7 communicating with a central passage, and a'Ycyl-indnical gauze lining in said central 7 my Qpaissage of said mouthpiece.

' IIAWlfiiQSiS whereof, We hereunto subscribe :QHIflQmGSt-hIS 6th day of February, 1929,

REGINALD BLACKBURN.-

Images