Adaptable layered heater system

Abstract

A layered heater is provided that comprises at least one resistive layer defining a circuit configuration, the circuit configuration comprising at least one resistive trace oriented relative to a heating target and comprising a material having temperature coefficient characteristics such that the resistive trace provides power commensurate with demands of the heating target. In one form, resistive traces of the resistive layer are a PTC material having a relatively high TCR and are oriented approximately perpendicular to a primary heating direction. In another form, resistive traces of the resistive layer are an NTC material having a relatively high BETA coefficient and are oriented approximately parallel to a primary heating direction.

Description

technical field [0001] The present invention relates generally to electric heaters, and more particularly to apparatus and methods for achieving a relatively constant temperature distribution in the presence of localized heat sinks. Background technique [0002] Layered heaters are typically used in space-constrained applications when heat output needs to vary across surfaces, applications requiring fast thermal response, or in ultra-clean applications where moisture or other contaminants can be transferred to conventional heaters . Layered heaters generally include layers of different materials, namely an insulating material and a resistive material, applied to a substrate. The insulating material is applied to the substrate first and provides electrical isolation between the substrate and the charged resistive material, and also reduces current leakage to ground during operation. A resistive material is applied to the insulating material in a predetermined pattern and pr...

AI Technical Summary

Problems solved by technology

Although the heat sink is somewhat compensated by the locally higher power density of the heater, the temperature distribution along the thermally gated nozzle still does not achieve a constant level and thus retains temperature variations in the molten resin, resulting in a suboptimal process

Additionally, prior art hot-gated nozzle heaters typically have no means of compensating for the variable heat sinks present in multi-drop chamber systems, as well as the inherent variations due to manufacturing tolerances in the nozzle body itself

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