Patent GB-1420825-A (GB)
Title: Electrical rc elements
IPC: H01G4/38
Filed: 1973-03-12
Abstract: 1420825 Resistance-capacitance assembly SIEMENS AG 12 March 1973 [8 May 1972] 11723/73 Heading H1R In a resistance-capacitance element, insulating foils 3 of, e.g. synthetic resin are respectively coated on one side with a high resistance coating 1 of, e.g. chromium nickel alloy, indium oxide, tin oxide or carbon and a low resistance coating 5 of, e.g. aluminium or conductive resin and stagger stacked (Figs. 4 to 6). Contact terminals A, B, C, D are defined by cross-cuts 6 extending partially into the stack from the two end faces and the element provides a 4-pole network with tapped resistor R and distributed capacitance K. In a modification (Figs. 7 to 9, not shown) three cuts extending transversely from one end face with the central cut extending through the entire overlap of the oppositely poled coatings define 5 contact terminals and provide two fourpole RC networks with two tapped resistors having distributed capacitors and a common ground. In a further modification (Figs. 10 to 12) the upper insulant foil 3 is coated on one side with high resistance coating, and below this is placed an insulant foil 16 metallized on both sides with low resistance coatings 10, 5. Thicker insulant foils 9 are interposed between the coated foils and beneath coating 5, while cuts 7 extend partially from opposite end faces through the overlap width to define external connections A, B, C, D and provide a network of three resistors R 1 , R 2 , R 3  in series, respectively shunted by capacitors K 1 , K 2 , K 3  to operate, e.g. as a frequency compensated voltage divider. In a further modification (Figs. 13 to 15, not shown) the first layer sequence comprises an insulant foil covered with a high resistance coating on one side and an intermediate insulant foil; a second layer sequence comprising two insulant foils each coated on one side with low resistance coatings, which are in staggered relationship. Reciprocal cuts extend cross-wise from opposite end faces through the entire overlap to define a series connection of three resistors respectively shunted by three capacitors.  In a further modification (Figs. 16 to 18) a low pass filter is fabricated from an insulant foil 3 coated on one side with high resistance material and overlying an uncoated intermediate insulant foil in a first sequence. A second sequence is provided by two insulant foils 3 each coated on one side with low resistance layers 5, 10; coatings 1, 10 having different widths. A cut 12 extending from one end partially transversely of the stack is longer than the width of coating 10 and shorter than the width of coating 5, and defines two resistors in series between terminals A, B, a common ground C, and shunt capacitors K 1 , K 2  across AC, BC.  In a further modification operating as a high pass filter (Figs. 19 to 21, not shown) a first layer sequence comprises an insulant foil coated on one side with a high resistance coating and an intermediate foil, while a second layer sequence is formed by a first insulant foil with a first low resistance coating and a second insulant foil also with a second low resistance coating which is isolated. A cut extending from an end face across the stack is longer than the width of the first low resistance coating but does not completely divide the second low resistance coating, and defines a high pass filter comprising resistances across input and output connected by series capacitors. Other modifications (Figs. 22 to 27, not shown) provide two resistors and two capacitors connected to a common ground, a resistancecapacitance T-section, and a capacitanceresistance T-section. Two-pole, 4-pole and 6- pole networks may also be fabricated. Multiple parallel connected coatings may be used to increase capacitance. The conductive coatings and insulant layers may be interwound and end connections may be obtained over projecting metal strips or Schoop metallizing.