GB595917A - Improvements relating to electromagnetic telephone instruments - Google Patents

Abstract

595,917. Telephone instruments. SIEMENS BROS. & CO., Ltd., and SPICER, J. H. July 9, 1945, No. 17428. [Class 40 (iv)] In a telephone instrument of the type in which an armature vibrates between two pole faces of opposite polarity, the distance between the pole-faces is determined by a spacer clamped between them and adapted to be attached to at least one of the pole pieces. The bar magnet 1, Fig. 1, has pole shoes 2, 8 attached to each end, each (such as 2) having a substantially flat L-shaped portion 3 (shown partly cut away) bent at right angles to the shoe 2, the horizontal limb of the L having bent-over portions 4, 5 forming two of the pole-pieces. The pole-pieces 9, 10 are similarly formed from the pole shoe attached to the other end of the bar magnet 1. The armature 14 having an ear 22 covered with a lapping 15 is gripped thereby at its lower end between the pole-pieces 5, 10. The upper end of the armature 14 is free to move between the pole-pieces 9, whose gap is maintained by U- shaped spacing members 18, 19 which clip over the pole-pieces 9. Screws such as 7, passing through holes such as 13 in the member 3, and 12 in the extension of the pole-shoe 8, serve to draw the pole-pieces together to clamp the lower end of the armature between the polepieces 5, 10 and the spacing members between the pole-pieces 4, 9. The lower limbs of the U-shaped clips 18, 19 may be joined by a horizontal bar for ease in assembling. The armature may alternatively be pivoted independently of the pole-pieces, spacers being provided for the pole-pieces 5, 10 as well as for 4, 9. Specification 547,728 is referred to.