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US 4,882,466 AGranted
Electrical devices comprising conductive polymers
AssigneeRaychem Corporation
InventorKevin J. Friel
Life of this patent
Estimating the term…
Abstract
An electrical device includes a laiminar resistive element which exhibits PTC behavior and two electrodes which exhibit ZTC behavior. The electrodes have a geometry which results in a resistance that is greater than the resistance of the resistive elements. The electrical device, which may be a heater, can be designed to produce a uniform power distribution over the surface of the device.
Claims20
An electrical device which comprises
- (1) a laminar resistive element which is composed of a conductive polymer composition which (a) exhibits PTC behavior, (b) comprises an organic polymer and, dispersed in the polymer, a particulate conductive filer, and (c) has a melting temperature, T.sub.m ;
- and
- (2) two electrodes which can be connected to a source of electrical power and which comprise a material which (a) has a resistivity of 1.0.times.10.sup.-6 to 1.0.times.10.sup.-2 ohm-cm, and (b) exhibits ZTC behavior at temperature less than T.sub.m, said electrodes
- (i) each having a length 1, of 0.1 to 1,000,000 inches and a width, w, of 0.005 to 10 inches such that the length to width ratio is at least 1000:1,
- (ii) each having a thickness of 0.0001 to 0.01 inch,
- (iii) each having a resistance, R.sub.e, of 0.1 to 10,000 ohms,
- (iv) each attached to a flat laminar surface of the resistive element, and
- said resistive element having a resistance, R.sub.cp, which is less than R.sub.e and is from 0.1 to 10,000 ohms when connected to a source of electrical power and the electrical device having a resistance, R.sub.h, the resistances R.sub.e, R.sub.cp and R.sub.h being measured when the electrodes are first connected to a source of electrical power with the whole device being at a uniform temperature of 23.degree. C.
5 more elements
A heated mirror for use on vehicles, which comprises
- (1) a mirror comprising a front mirrored surface and a back surface;
- and
- (2) attached to the back surface of the mirror, a heater which comprises
- (a) a laminar resistive element which is composed of a conductive polymer composition which exhibits PTC behavior;
- (b) two electrodes which can be connected to a source of electrical power and which comprise a material which has a resistivity of 1.times.10.sup.-6 to 1.times.10.sup.-4 ohm-cm exhibits ZTC behavior, said electrodes
- (i) each having a length of 10 to 1000 inches and a width of 0.005 to 1 inch such that the length to width ratio is at least 1000:1,
- (ii) each having a thickness of 0.0005 to 0.005 inch,
- (iii) each having a resistance, R.sub.e, of 0.1 to 1000 ohms,
- (iv) each attached to a flat laminar surface of the resistive element, and
- (v) together covering 10 to 90% of the surface area of the resistive element,
- said resistive element having a resistance R.sub.cp which is less than R.sub.e and is from 0.1 to 1000 ohms when connected to a source of electrical power and the heater having a resistance R.sub.h, the resistances R.sub.e, R.sub.cp, and R.sub.h being measured when the electrodes are first connected to a source of electrical power with the whole device being at a uniform temperature of 23.degree. C.
8 more elements
Dependencies are inferred from the claim text.