GB390584A - Improvements in telephonic receivers and loud speakers - Google Patents

Abstract

390,584. Loud-speakers. LANCHESTER, F. W., Dyott End, Oxford Road, Moseley, Birmingham. Jan. 7,1932, No. 460. [Class 40 (iv).] A moving coil loud-speaker or telephone receiver is provided with adjustment mechanism for centring the speech coil in the field gap comprising a means of adjustment of the outer pole plate or magnet assemblage longitudinally at one anchorage and laterally at its other or an opposite anchorage. Fig. 2 shows a construction of loud-speaker similar to that described in Specification 368,708 comprising a pole plate 1, permanent magnet 2 and a centre pole 3 which forms with a hole 16 in the plate 1 the field gap in which the coil 11 carried by the cone 9 is situated. A non- magnetic ring 4 serves to maintain the correct axial alignment between the pole 3 and plate 1, the component parts of the magnet assemblage being held together by studs and nuts 5. The cone is carried om a flexible surround 10 in a baffle 6 to which the magnet assemblage is secured by eccentric bolts 7. 8 and nuts 17 with interposed spacer blocks 13. One end of the plate 1 is drilled at 14 to receive the eccentric portion of bolt shank 7 which in its normal or mean position is at right-angles to the length of the plate whilst the other end of the plate is slotted at 15 to receive the eccentric portion of bolt shank 8 which in its normal or mean position is in line with the plate so that rotation of bolt 7 produces a longitudinal movement of the plate whilst rotation of bolt 8 produces a lateral movement thereof. According to a modification, Fig. 3, a magnet assemblage of the annular pot type (not shown) is carried by a four-armed spider 20, two opposite arms of which are attached to the baffle 6 by eccentric bolts 7, 8, the other two arms being secured to the baffle by plain bolts 18 in clearance holes 19. - If desired, all the arms may be secured by eccentric bolts. According to a further modification, Figs. 4 and 5 (not shown), the eccentric bolts may be replaced by ordinary bolts fitted with eccentric bushes.