Film-type cylindrical resistor

Claim 2

A film-type resistor, which comprises: a. an elongated cylindrical substrate, a. a resistive film provided adherently on the cylindrical surface of said substrate, c. a plurality of termination film strips formed of conductive material, said termination film strips being adherently provided in at least partially laminated relationship relative to portions of said resistive film, said termination film strips being elongated and extending in directions generally longitudinally of said substrate, said termination film strips being spaced relative to each other circumferentially of said cylindrical surface, said termination film strips defining between them at least one resistor element composed of at least part of said resistive film, and through which currents flow in paths generally circumfereNtial to said substrate, said resistor element and said termination film strips being so shaped and disposed that said circumferential current paths through said resistor element are relatively long at the central region of said substrate, and relatively short at the end portions thereof, and d. means to connect one of said termination film strip to one lead and to connect another of said termination film strips to another lead, whereby when said leads are connected in an electrical power circuit, the amount of electrical heating occurring in said resistive film at said central region of said substrate is substantially less than the amount of such heating occurring at said end portions.

Claim 3

The invention as claimed in claim 1, in which said resistive film is uniform in thickness.

Claim 4

The invention as claimed in claim 1, in which each of said termination film strips is relatively wide adjacent each end portion of said substrate, is relatively narrow at the central region of said substrate, and becomes progressively wider in both directions away from said central region.

Claim 5

The invention as claimed in claim 3, in which each of said termination film strips is a prolate double trapezoid having a common side, said common side being at said central region of said substrate, the two bases of said double trapezoid being remote from said central region.

Claim 6

The invention as claimed in claim 1, in which the shapes and positions of said termination film strips are such that, when said leads are connected in an electrical power circuit, the resistive heating causes the temperature of said resistor to be substantially uniform along the length of said substrate.

Claim 7

The invention as claimed in claim 1, in which said means recited in clause (d) comprises metal end caps respectively mounted over opposite ends of said substrate, one of said end caps being electrically connected to said one of said termination film strips and to said one lead, the other of said end caps being electrically connected to said other of said termination film strips and to said other lead.

Claim 8

The invention as claimed in claim 6, in which said resistive film is not present on the end portions of said substrate beneath said end caps, and in which said means recited in clause (d) comprises two additional termination films formed of highly conductive material, one of said additional termination films being provided adherently on said substrate beneath said one end cap and being connected integrally to said one termination film strip, the other of said additional termination films being provided adherently on said substrate beneath said other end cap and being connected integrally to said other termination film strip.

Claim 9

The invention as claimed in claim 1, in which said resistive film is one resulting from the silk-screening of resistive material onto said sustrate.

Claim 10

The invention as claimed in claim 1, in which said substrate is solid, not hollow, and is formed of ceramic.

Claim 11

A relatively low resistance cylindrical film-type resistor having substantially uniform temperature characteristics, which comprises: a. an elongated cylinder forming a substrate, b. a uniform-thickness resistive film provided adherently on the exterior cylindrical surface of said substrate, said film being substantially tubular and having end regions which are respectively spaced from the ends of said substrate, c. first termination film means provided adherently on said substrate, said first termination film means being generally comb shaped in that it has spine means at one end of said substrate and spaced from the corresponding end region of said resistive film, and furthermore has elongated tooth means extending longitudinally of said substrate in circumferentially-spaced relationship about said exterior cylindrical surface, said tooth means being laminated relative to said resistive film, d. second termination film means provided adherently on said substrate, said second termination film means being generally comb shaped in that it has spine means at the other end of said substrate and spaced from the corresponding end region of said resistive film, and furthermore has elongated tooth means extending longitudinally of said substrate in circumferentially-spaced relationship about said exterior cylindrical surface, said tooth means being laminated relative to said resistive film, said tooth means intermeshing said tooth means of said first termination film means in circumferentially spaced relationship, said tooth means of said first and second termination film means being so shaped and located, and the portions of said resistive film between said tooth means being so shaped and located, that currents flowing through said resistive film generally circumferentially of said substrate, between adjacent ones of said tooth means, must flow relatively long distances at the central region of said resistive film, and relatively short distances at the end portions thereof, and e. electrical connector means connected to said spine means at opposite ends of said substrate.

Claim 12

A relatively low resistance cylindrical film-type resistor having substantially uniform temperature characteristics, which comprises: a. an elongated cylinder forming a substrate, b. a uniform-thickness resistive film provided adherently on the exterior cylindrical surface of said substrate, said film being substantially tubular and having end regions which are respectively spaced from the ends of said substrate, c. first termination film means provided adherently on said substrate, said first termination film means being generally comb shaped in that it has spine means at one end of said substrate and spaced from the corresponding end region of said resistive film, and furthermore has elongated tooth means extending longitudinally of said substrate in circumferentially-spaced relationship about said exterior cylindrical surface, said tooth means being laminated relative to said resistive film, d. second termination film means provided adherently on said substrate, said second termination film means being generally comb shaped in that it has spine means at the other end of said substrate and spaced from the corresponding end region of said resistive film, and furthermore has elongated tooth means extending longitudinally of said substrate in circumferentially-spaced relationship about said exterior cylindrical surface, said tooth means being laminated relative to said resistive film, said tooth means intermeshing said tooth means of said first termination film means in circumferentially spaced relationship, said tooth means of said first and second termination film means being so shaped and located, and the portions of said resistive film between said tooth means being so shaped and located, that currents flowing through said resistive film generally circumferentially of said substrate, between adjacent ones of said tooth means, must flow relatively long distances at the central region of said resistive film, and relatively short distances at the end portions thereof, and e. electrical connector means connected to said spine means at opposite ends of said substrate.

Claim 13

The invention as claimed in claim 10, in which each of said tooth means of each of said termination film means is relatively wide adjacent each end region of said resistive film, is relatively narrow adjacent the central part of said resistive film, and progressively narrows in directions from each of said end regions toward said central part.

Claim 14

The invention as claimed in claim 10, in which the shapes and locations of said tooth means are such as to cause electrical heating of said substrate to a substantially uniform temperature along the length thereof.

Claim 15

The invention as claimed in claim 10, in which each of said tooth means is shaped generally as a prolate double trapezoid the bases of which are respectively adjacent said end regions of said resistive film, the sides opposite said bases being coincident with each other and being at the central part of said resistive film.

Claim 16

The invention as claimed in claim 13, in which said tooth means divide said resistive film into a plurality of circumferentially spaced resistor elements, each of which is shaped generally as a prolate double trapezoid having a common base at the central part of said resistive film.

Claim 17

The invention as claimed in claim 10, in which each of said tooth means is generally hourglass-shaped.

Claim 18

The invention as claimed in claim 10, in which at least one of said tooth means is relatively wide adjacent each end region of said resistive film, and relatively narrow adjacent the central part of said resistive film.

Claim 19

The invention as claimed in claim 10, in which said electrical connector means recited in clause (e) comprises conductive end caps mounted over said spine means at opposite ends of the resistor.

Claim 20

The invention as claimed in claim 10, in which said tooth means overlie said resistive film in adherent relationship thereto.

Claim 21

The invention as claimed in claim 18, in which a groove is provided in said resistive film between adjacent ones of said tooth means, the length of said groove being such as to cause said resistor to have a desired resistance valve.

Claim 22

A cylindrical resistor having uniform temperature characteristics, and having a low resistance value, which comprises: a. an elongated cylindrical substrate, b. a plurality of elongated resistive film elements adherently provided genrerally longitudinally on said substrate in circumferentially spaced relationship thereabout, said elements having relatively long dimensions circumferentially of said substrate at the central region thereof, and having relatively short dimensions circumferentially of said substrate at the end portions thereof, and c. termination means to connect said resistive film elements in parallel-circuit relationship relative to each other and also in such manner that the current flow paths through each of said resistive film elemenTs are generally circumferential to said substrate, whereby the amount of resistive heating occurring at said central region is less than at said end portions.

Claim 23

A cylindrical resistor having uniform temperature characteristics, and having a low resistance value, which comprises: a. an elongated cylindrical substrate, b. a plurality of elongated resistive film elements adherently provided genrerally longitudinally on said substrate in circumferentially spaced relationship thereabout, said elements having relatively long dimensions circumferentially of said substrate at the central region thereof, and having relatively short dimensions circumferentially of said substrate at the end portions thereof, and c. termination means to connect said resistive film elements in parallel-circuit relationship relative to each other and also in such manner that the current flow paths through each of said resistive film elemenTs are generally circumferential to said substrate, whereby the amount of resistive heating occurring at said central region is less than at said end portions.

Claim 24

The invention as claimed in claim 20, in which said circumferential dimensions change progressively along the length of said resistive film elements.

Claim 25

The invention as claimed in claim 20, in which the shapes and location of said resistive film elements are such that the temperature of said substrate is substantially constant along the length thereof.