GB261154A - Improvements in or relating to sound producing apparatus - Google Patents

Abstract

261,154. O'Donnell, P. S. Sept. 30, 1925. Loud-speakers; magnetic instruments diaphragms .-Relates to sound - reproducing apparatus such as telephonic loudspeakers. According to the invention, vibrations are transmitted from a primary vibrator to a secondary vibrator such as a sound-emitting diaphragm through two diamonds or other jewels in contact with each other. In the loud-speaker shown, which embodies tuned resonating gongs 13 and other features described in Specification 256,677, vibrations are transmitted from the armature 2 of an electromagnet 1 to a conical diaphragm 3 through two diamonds 4, 5, one of which, 5, is mounted on the end of a rod 6 which passes through a sleeve 8 and is connected to the diaphragm 3. The other diamond 4 is contained in a cup 7 secured to a glass disc 17, which is screwed to the armature 2, a washer of ebonite &c. being interposed. A spring 6a acting on the rod 6, presses the diamonds together. The vibrations of the armature are at right angles to the rod 6, and are transmitted to the rod by reason of the irregularities in the surfaces of the jewels in rubbing contact. The armature is mounted between pole-pieces 1<b>, and is carried by a resilient bridge 2<a>, one end of which is fixed to a base 1<c>, and the other end being adjustable, by means of a knob 2<b>, in a direction at right angles to the base. The base 1<c>, which carries the core 1<a> of the electromagnet, is cemented to a glass disc 10, supported in grooves lined with rubber &c. in feet 12 attached to the back of the casing of the instrument. Auxiliary diaphragms 16 are rigidly mounted on an extension of the sleeve 8, as described in Specification 259,103. The diaphragm 3 is made of silk, which may be mounted on a light framework and coated with a solution of celluloid and a layer of varnish; or it may be pleated. Its periphery is supported by strings 3<c>. The first Provisional Specification also describes a loud-speaker having a main conical diaphragm and auxiliary glass &c. diaphragms, and in which the electromagnet is enclosed in a small rectangular space formed by a truncated pyramid of thin wood, mounted on a base. The second Provisional Specification describes a loudspeaker similar to that last referred to, in which the casing, provided with tuned gongs, is a rectangular box having a slotted front. Adjustment of the contact between two diamonds through which vibrations are transmitted from the magnetic armature to the diaphragm is effected by means of a knob on the end of a rod which carries the main and auxiliary diaphragms, the rod extending through the front of the box.