Two-wire layered heater system

Abstract

A heater is provided that includes a resistive layer formed by a layered process (e.g., thick film, thin film, thermal spray, and sol-gel) and two electrical lead wires connected to the resistive layer. The resistive layer has sufficient temperature coefficient of resistance characteristics such that the resistive layer is a heater element and a sensor, and the resistive layer is in communication with a two-wire controller through the two electrical lead wires. Preferably, the sensor is a temperature sensor, and the heater includes additional layers formed by layered processes.

1 . A layered heater comprising:
 a substrate;   a dielectric layer disposed on the substrate;   a resistive layer disposed on the dielectric layer, the resistive layer having sufficient temperature coefficient of resistance characteristics such that the resistive layer is a heater element and a temperature sensor;   a protective layer disposed over the resistive layer;   two electrical lead wires connected to the resistive layer; and   a two-wire controller connected to the resistive layer through the two electrical lead wires, wherein the two-wire controller determines temperature of the layered heater using the resistance of the resistive layer and simultaneously controls heater temperature accordingly through the two electrical lead wires.   
     
     
         2 . The layered heater according to  claim 1 , wherein the two-wire controller comprises a DC bias control for calculation of the resistance of the resistive layer. 
     
     
         3 . The layered heater according to  claim 1 , wherein the two-wire controller comprises an AC bias control for calculation of the resistance of the resistive layer. 
     
     
         4 . The layered heater according to  claim 1 , wherein the two-wire controller comprises high conduction angle firing. 
     
     
         5 . The layered heater according to  claim 1 , wherein the two-wire controller comprises a shunt resistor for calculation of the resistance of the resistive layer. 
     
     
         6 . The layered heater according to  claim 1 , wherein the two-wire controller further comprises a microprocessor. 
     
     
         7 . The layered heater according to  claim 1 , wherein the two-wire controller further comprises firmware. 
     
     
         8 . The layered heater according to  claim 1 , wherein the layered heater is formed by a layered process selected from the group consisting of thick film, thin film, thermal spray, and sol-gel. 
     
     
         9 . An apparatus comprising:
 a resistive layer formed by a layered process selected from the group consisting of thick film, thin film, thermal spray, and sol-gel; and   two electrical lead wires connected to the resistive layer,   wherein the resistive layer has sufficient temperature coefficient of resistance characteristics such that the resistive layer is a heater element and a sensor, and the resistive layer is in simultaneous communication with a two-wire controller through the two electrical lead wires.   
     
     
         10 . The apparatus according to  claim 9  further comprising a substrate, wherein the resistive layer is formed on the substrate. 
     
     
         11 . The apparatus according to  claim 9  further comprising a dielectric layer, wherein the resistive layer is formed on the dielectric layer. 
     
     
         12 . The apparatus according to  claim 11  further comprising a substrate, wherein the dielectric layer is formed on the substrate. 
     
     
         13 . The apparatus according to  claim 9 , wherein the sensor is a temperature sensor. 
     
     
         14 . A heater comprising:
 a resistive layer formed by a layered process selected from the group consisting of thick film, thin film, thermal spray, and sol-gel,   wherein the resistive layer has sufficient temperature coefficient of resistance characteristics such that the resistive layer is a heater element and a temperature sensor, and the resistive layer is in simultaneous communication with a two-wire controller through two electrical lead wires.   
     
     
         15 . The apparatus according to  claim 14  further comprising a substrate, wherein the resistive layer is formed on the substrate. 
     
     
         16 . The apparatus according to  claim 14  further comprising a dielectric, wherein the resistive layer is formed on the dielectric. 
     
     
         17 . A layered heater comprising a resistive layer formed by a layered process selected from the group consisting of thick film, thin film, thermal spray, and sol-gel, wherein the resistive layer has sufficient temperature coefficient of resistance characteristics such that the resistive layer is a heater element and a sensor, and the resistive layer is in simultaneous communication with a two-wire controller through two electrical lead wires. 
     
     
         18 . The apparatus according to  claim 17  further comprising a substrate, wherein the resistive layer is formed on the substrate. 
     
     
         19 . The apparatus according to  claim 17  further comprising a dielectric layer, wherein the resistive layer is formed on the dielectric layer. 
     
     
         20 . The apparatus according to  claim 19  further comprising a substrate, wherein the dielectric layer is formed on the substrate. 
     
     
         21 . The apparatus according to  claim 19  further comprising a protective layer formed over the resistive layer. 
     
     
         22 . The apparatus according to  claim 17 , wherein the sensor is a temperature sensor.