Electrical heating device
First Claim
Patent Images
1. An electrical heating device for producing a substantially uniform thermal image, comprising:
- an electrically insulating substrate;
a pair of spaced-apart, elongated conductors;
a semi-conductor pattern carried on said substrate and including a plurality of spaced-apart heating portions extending between and electrically connected to said conductors;
said heating portions arranged to produce the substantially uniform thermal image at an image producing zone of the substrate between said conductors;
each of a plurality of said heating portions including a first portion positioned in said image producing zone and a second portion positioned outside said image producing zone between said image producing zone and a respective one of said conductors; and
said first portions of each of said plurality of heating portions being closely adjacent each other such that the portion of said semi-conductor pattern within said image producing zone of said heating device produces a substantially uniform watt density within said image producing zone when a predetermined voltage is applied across said conductors.
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Abstract
An electrical heating device comprises a substrate, a pair of parallel, spaced apart elongated conductors extending longitudinally of the substrate, and a semi-conductor pattern carried on the substrate and electrically connected to and extending between the conductors. The semi-conductor pattern produces a thermal image for an infrared target. In some embodiments, the thermal image is irregular or circular in shape and the semi-conductor pattern includes a plurality of transversely-spaced bars having relatively wide portions outside, and relatively thin portions within, the area producing the thermal image.
28 Citations
16 Claims
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1. An electrical heating device for producing a substantially uniform thermal image, comprising:
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an electrically insulating substrate; a pair of spaced-apart, elongated conductors; a semi-conductor pattern carried on said substrate and including a plurality of spaced-apart heating portions extending between and electrically connected to said conductors; said heating portions arranged to produce the substantially uniform thermal image at an image producing zone of the substrate between said conductors; each of a plurality of said heating portions including a first portion positioned in said image producing zone and a second portion positioned outside said image producing zone between said image producing zone and a respective one of said conductors; and said first portions of each of said plurality of heating portions being closely adjacent each other such that the portion of said semi-conductor pattern within said image producing zone of said heating device produces a substantially uniform watt density within said image producing zone when a predetermined voltage is applied across said conductors. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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Specification