GB285454A - Sound recording and reproducing apparatus - Google Patents

Abstract

285,454. Hallam, H., and Helary, J. R. M. Feb. 17, 1927, [Convention date]. Magnetic instruments; diaphragms; phonographic recorders and reproducers.-A sound recording and reproducing device, more particularly for use in connection with gramophones, comprises the combination of a conductor formed by a non-coiled wire or blade adapted to move perpendicularly to the lines of force of a magnetic field, and means, such as elastic or deformable material, for guiding the conductor over the whole of the portion thereof situated between the magnetic poles so as to prevent any parasitic vibrations of the conductor or any movement thereof which is not strictly perpendicular to the lines of force of the magnetic field. Fig. 2 shows a construction in which a conductor 9, situated in the gap between the poles of a magnet 8, carries at one end a stylus holder 10, whilst its other end is connected to a pivot pin 11 mounted in rubber bearings 12, 13. A screw 14 acting on the bearing 13 regulates the pressure on the pin 11. The conductor 9 is prevented from being displaced in the direction of the lines of force by damping pads 15 of rubber, the width of the air gap and the pressure of the pads on the conductor being adjustable by means of a stirrup 16 and screw 17. The circuit leads 24, 25 are arranged one on each side of the air gap. In a modified construction, Fig. 3, the conductor 9a is made longer and formed with an enlarged portion 18 embedded in a rubber block 19. Rubber bosses 20 situated on either side of the conductor may be provided on the magnet limbs as shown, or may be located at several points or over the whole length of the limbs. In a further modification, Fig. 6, the magnet 23 is enclosed in a two-part box 22, rubber pads 21 fixed to the two portions of the box being adapted to bear on the edges of the conductor. In order to avoid eddy currents, the conductor is preferably built up of laminµ 26. Fig. 8, connected at their ends by conductors 27, 28. The Specification as open to inspection under Sect. 91 (3) (a) comprises also a construction of microphone or loud-speaker, Fig. 9 (Cancelled), in which a diaphragm 33 of light fabric or rubber having one or more conductors 34 embedded therein is supported on arms 31 fixed to the outer faces of the limbs of the magnet 30. The ends of the conductors 34 are connected by conductors 35, as shown in Fig. 10 (Cancelled). According to a further construction, a number of sets of conductors are incorporated in a single diaphragm each set co-operating with an independent magnet A horn may be provided in front of the diaphragm. This subject-matter does not appear in the Specification as accepted.