GB140070A - Improvements in and relating to telephone transmitters - Google Patents

Abstract

140,070. Miessner Inventions Corporation, (Assignees of Miessner, B. F.). March 12, 1919, [Convention date]. Microphones ; mouthpieces; magnetic instruments. - Relates to microphone transmitters of the type in which sound is admitted equally to both sides of the diaphragm, and consists in supporting this diaphragm within a protective casing and in screening the microphone itself from sound. In the form shown in Figs. 1 and 3, the casing 25 and cap 29 are pierced with holes, or the cap 29 may have an open centre. The main diaphragm is damped by padded springs. The carbon button and mica diaphragm 20, Fig. 3, are screened by a cylinder 31 with interior flange 32, and by a rubber disk 33. In a simpler form, the microphone is mounted at the centre of a spider with two or more radial arms which forms the back of the instrument, and co-operates to support the diaphragm with a cap which has its centre obstructed by a spider and is provided with spring fingers adapted to clasp the periphery of the spider, which is formed as an annular casing. In the form shown in Fig. 6, the microphone is screened by a casing 50 provided with a hollow neck 53 which contains a stem 57 connecting the carbon button 19 to the diaphragm D'. The latter is arranged in a flat head 55 so that an equally effected area is exposed on either side through holes 61. The capsule 52 is screwed on to the stem 57 by means of the saw-cut 59, and is clamped in position by a set-screw. The Specification as open to inspection under Sect. 91 (3) (a) describes a magnetic instrument, Fig. 8, supported on an open spider frame, the which raises the wipers to the desired level, which coils 6 being short in order to reduce their screening effect on the diaphragm, and the aperture 2<b> being so sized as to equalize the pressure on the two sides of the diaphragm. This subject-matter does not appear in the Specification as accepted.