Patent GB-374180-A (GB)
Title: Improvements in or relating to electrical reproducer devices for use with gramophonerecords
IPC: G11B3/42
Filed: 1931-03-20
Abstract: 374,180. Gramophone pick-ups and mounting devices. PACENT ELECTRIC CO. Inc., 91, 7th Avenue, New York, U.S.A. March 20,1931, No. 8659. Convention date, Oct. 10, 1930. [Class 40 (ii).] A gramophone pick-up is carried by a swing- ing arm having a hollow head portion pivoted on a base, an electrical control device being located in the hollow head and provided with exposed actuating means. In the construction shown, a pick-up 14 is pivoted at 15 on an arm 16 which is secured to a hollow casing or head 20. This is pivotally supported on a post 24 fixed to a base 29, the post being engaged by arms 23, 25 extending from an arcuate bracket 22 screwed to the casing 20, a ball 26 in the upper arm 23 providing a step bearing. The casing 20 houses within its upper portion a volume-control and cut-out device 35 for the pick-up. This device comprises a resistance 36 and contact-member 38, the connection therewith of the pick-up coil 37 being shown diagrammatically in Fig. 8. A fixed contact 39 at one end of the resistance is adapted to be engaged by the part 38 when it is desired to short-circuit the pick-up and change over, in a radio-gramophone, to radio-operation. The control device 35 is supported on a bracket 48 within the casing 20, and the stem 33 of the movable contact arm protrudes through a cap 31 at the top of the casing, and carries an external knot 34. The pick-up itself is enclosed in a casing 95 detachably secured to a base plate 52, having a neck 53 which is pivoted on a stud 15 between ears 54 on the arm 16, which is of inverted channel shape. Downward swinging movement is limited by engagement of a flange 55 on the neck with the end of the arm, so that the pick-up is clear of the record when no needle is in position. The magnet 57 is secured on the base 52 by a screw clamp 58 and a clip 59, and slight adjustment may be effected by rocking the magnet about bearing studs 61 by means of a screw 62. Polepieces 63 having inclined faces 65 abutting against the ends of the magnet arms are secured in position by screws 66 passing through the baseplate. The polepieces are substantially 0-shaped, and hold between them the coil 37. The lower branch 68 of each polepiece may be a separate member, slotted to fit over a lug 71 on the body of the polepiece and clamped in position by a non-magnetic bridge 72. The pick-up leads extend through the back of the baseplate to terminals 99 on an insulating base screwed to the back of the hollow neck 53. Wires from these terminals pass along the underside of the arm 16. The terminals and the ends of the wires are protected by an insulating cover sheet 102. The Specification as open to inspection under Sect. 91 (3) (a) describes the pick-up construction in further detail. It describes and shows in Fig. 5 (Cancelled) how the armature 79 is pivoted by rubber-cushioned projections mounted in bearings formed by the lower members 68 of the polepieces and the bridge 72. The upper members of the polepieces are grooved to receive rubber damping pads 80 engaging the armature, means for adjusting the damping being provided by brackets 83 on an upper non-magnetic bridge-piece 85. A modified construction of polepiece, with integrally formed polar projections, is also described. This subject-matter does not appear in the Specification as accepted.