Thick film elements
First Claim
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1. A thick film resistive heating element comprising:
- an electrically insulative substrate;
a thick film resistive track applied to a surface of said electrically insulative substrate and terminating in respective electrical contact portions, said resistive track having a thickness; and
an encapsulating insulating layer applied to said thick film resistive track but not over said electrical contact portions, said encapsulating insulating layer applied over at least a portion of said surface of said electrically insulative substrate in order to protect said thick film resistive track, an area of said surface of said electrically insulative substrate and of said thick film resistive track being uncovered by said encapsulating insulating layer so as to define a window adapted such that a temperature sensitive controller can be placed in direct contact with at least one of a portion of said thick film resistive track and a portion of said electrically insulative substrate, the resistive track within the window comprises a plurality of tracks which are thinner than the thickness of the resistive track outside the window.
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Abstract
A thick film resistive heating element having a thick film resistive track applied to the surface of an electrically insulative substrate. An encapsulating insulating layer is applied over the track to protect it while an area of the element is left uncovered by the encapsulating layer so as to define a window. A portion of a temperature sensitive control device is then placed in direct contact with the track and/or the electrically insulative substrate through the window. The window in the element is located in that area of the element which will be uncovered by the liquid prior to the rest of the element as the liquid boils away or is evacatuated from the vessel.
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Citations
6 Claims
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1. A thick film resistive heating element comprising:
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an electrically insulative substrate; a thick film resistive track applied to a surface of said electrically insulative substrate and terminating in respective electrical contact portions, said resistive track having a thickness; and an encapsulating insulating layer applied to said thick film resistive track but not over said electrical contact portions, said encapsulating insulating layer applied over at least a portion of said surface of said electrically insulative substrate in order to protect said thick film resistive track, an area of said surface of said electrically insulative substrate and of said thick film resistive track being uncovered by said encapsulating insulating layer so as to define a window adapted such that a temperature sensitive controller can be placed in direct contact with at least one of a portion of said thick film resistive track and a portion of said electrically insulative substrate, the resistive track within the window comprises a plurality of tracks which are thinner than the thickness of the resistive track outside the window. - View Dependent Claims (2, 3, 4, 5, 6)
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Specification