GB840059A - "capacitors" - Google Patents

Abstract

840,059. Capacitors. STANDARD TELEPHONES & CABLES Ltd. Nov. 15, 1957, No. 35642/57. Class 37. The manufacture of a rolled capacitor comprises the steps of metallizing one surface 2 of an insulating strip 1, the metal extending to only one longitudinal edge of the strip, to form a first electrode; and rolling the metallized strip with a second electrode 3 so that a plurality of successive turns of the roll are offset in the same direction to expose a portion 5 of the metallizing. The insulating strip 1 is of plastic or impregnated paper and metallized on both surfaces, except for portions on respective longitudinal edges, to constitute the electrodes 2, 3; and is rolled with a second insulating strip 4 to form the capacitor. Portions 5, 6 of both electrodes are exposed by offsetting adjacent turns of the roll, and electrical connections to these portions are provided by spray coatings 7 and 8. In another embodiment, Fig. 2 (not shown), two insulating strips, metallized on one side only, are rolled with a third insulating strip which may be twice the thickness of the metallized ones. Alternatively, Fig. 3 (not shown), two strips each metallized on both sides may be wound together. A foil coated on both sides and over or beyond one edge with insulating material constitutes the second electrode in the embodiments of Figs. 4, 5, 6 (not shown), and metallizing on one or both sides of the resulting insulating layer constitutes the first electrode. A first group of successive turns of the roll may be offset in one direction, and a second group in the opposite direction, Fig. 6 (not shown). Inserts of plastic or plastic coated metal may be placed in the roll to project from its ends and thus improve adhesion of the spray coatings 7, 8. Apparatus for producing offset windings, Fig. 7, comprises a rotating shaft 64 carrying the capacitor roll and adapted to drive, through a gear-box 68, a cam 70 abutting the end of an axially slidable former 72, spring-urged 73 into contact with the cam 70, and carrying a spool 75 of metallized coated foil as described in the embodiment of Fig. 5 (not shown). As the capacitor roll is wound, the former 72 is moved axially to and fro by the cam 70 so that successive turns of the roll are relatively offset. Specification 587,935 is referred to.