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 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 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 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 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.