Patent GB-911773-A (GB)
Title: Improvements in or relating to capacitors
Inventor: HALL MICHAEL MAURICE JAMES
IPC: H01G4/30
Filed: 1958-02-19
Abstract: 911,773. Capacitors. BRITISH DIELECTRIC RESEARCH Ltd. Feb. 18, 1959 [Feb. 19, 1958], No. 5432/58. Class 37. A capacitor is constructed having its electrodes formed of sheets of metal foil interleaved with insulating dielectric; one or each foil electrode being folded so that its raw edges are removed from the electric fold of the capacitor; e.g. by screening therefrom by other parts of the same electrode or by positioning the raw edges in juxtaposition to project beyond the dielectric. An electrode foil 1, Fig. 1 (a) to (e), has its longitudinal edges 2 folded inwards at 4 along lines x, x<SP>1</SP> and again at 5 along parallel lines y, y<SP>1</SP> so that each raw edge is screened by folds 4, 5, Fig. 2. The lateral edges 3, Fig. 3 (a), (b), are folded inwards at 7 along line p, p<SP>1</SP> and again at 8 along parallel lines q, q<SP>1</SP> to be similarly screened. Alternatively, the corners of the ends are folded over at 45 degrees to the longitudinal edges into an apex 9 which is then folded along line s, s<SP>1</SP> and again at 10 along parallel line t, t<SP>1</SP>, Fig. 4 (a) to (d). In a capacitor. Fig. 5, insulating strips 15 are wound with axially-staggered electrode foils 14 each having one longitudinal raw edge 16 protruding from the roll and one edge screened by double folding at 18 adjacently to the centre line of the insulating strips. The outer end of each strip is folded at 45 degrees to the longitudinal edges to protrude from the same side of the roll as edge 16, and the inner end 14 may be correspondingly folded. In a modification, Fig. 6, not shown, both longitudinal edges of the strips are doublefolded and the inner ends are folded as in Fig. 4, while the outer ends are folded over at 45 degrees to the longitudinal edges to form integral tags protruding one from each side of the roll. A stack capacitor, Fig. 7 (not shown), is built of alternate dielectric layers and foil electrodes double folded as in Figs. 1 and 2 to screen the longitudinal edges, and double folded as in Fig. 4 to screen one end edge of each, the remaining ends protruding from opposite sides of the stack as tags which are correspondingly interconnected. An electrode foil 27, Figs. 8 (a), (b), may be folded along longitudinal median line v, v<SP>1</SP> to bring the raw edges 28 into juxtaposition, and an end 29 may be folded along line w, w<SP>1</SP>, Fig. 9 (a), (b), at 45 degrees to v, v<SP>1</SP> so as to juxtapose the end and longitudinal edges, and a pair of such folded foils may be axially staggered and wound with an interleaving insulating sheet, Fig. 10 (not shown); the inner and outer ends being folded as in Fig. 9 so that the respective edges of each foil protrude on opposite sides of the roll for connection. A foil folded as in Fig. 8 may be folded again along a median line normal to the first fold to bring the raw edges to two adjacent sides, Fig. 11 (not shown), and a stack capacitor may be built of such double-folded foils interleaved with dielectric layers, Fig. 12 (not shown), with the edges of alternate sheets protruding from opposed adjacent sides of the stack for interconnection.