Variable watt density layered heater

Abstract

A layered heater is provided that includes at least one resistive layer having a resistive circuit pattern, the resistive circuit pattern defining a length, a width, and a thickness, wherein the thickness varies along the length of the resistive circuit pattern and/or the width of the resistive circuit pattern for a variable watt density. The present disclosure also provides layered heaters having a resistive circuit pattern with a variable thickness along with a variable width and/or spacing of the resistive circuit pattern in order to produce a variable watt density.

1 . A layered heater comprising: 
 a substrate;    a resistive layer formed on the substrate, the resistive layer comprising a resistive circuit pattern, the resistive circuit pattern defining a trace having a length, a thickness, and a spacing; and    a protective layer formed on the resistive layer,    wherein the thickness of the resistive circuit pattern varies along the length of the trace of the resistive circuit pattern for a variable watt density.    
   
   
       2 . The layered heater according to  claim 1 , wherein the spacing is constant.  
   
   
       3 . The layered heater according to  claim 1 , wherein the spacing is variable.  
   
   
       4 . The layered heater according to  claim 1 , wherein the resistive circuit pattern further comprises a width that is constant.  
   
   
       5 . The layered heater according to  claim 1 , wherein the resistive circuit pattern further comprises a width that is variable.  
   
   
       6 . The layered heater according to  claim 1 , wherein the layered heater is selected from a group consisting of thick film, thin film, thermal spray, and sol-gel.  
   
   
       7 . The layered heater according to  claim 1 , wherein the resistive circuit pattern is selected from a group consisting of series, parallel, and series-parallel.  
   
   
       8 . The layered heater according to  claim 1 , wherein the variable thickness is continuous.  
   
   
       9 . The layered heater according to  claim 1 , wherein the variable thickness is non-continuous.  
   
   
       10 . A layered heater comprising: 
 a resistive layer comprising a resistive circuit pattern, the resistive circuit pattern defining a trace having a length, a thickness, and a spacing;    terminal pads in contact with the resistive layer adapted to connect the resistive layer to a power source; and    a protective layer formed on the resistive layer,    wherein the thickness of the resistive circuit pattern varies along the length of the trace of the resistive circuit pattern for a variable watt density.    
   
   
       11 . The layered heater according to  claim 10 , wherein the spacing is constant.  
   
   
       12 . The layered heater according to  claim 10 , wherein the spacing is variable.  
   
   
       13 . The layered heater according to  claim 10 , wherein the resistive circuit pattern further comprises a width that is constant.  
   
   
       14 . The layered heater according to  claim 10 , wherein the resistive circuit pattern further comprises a width that is variable.  
   
   
       15 . The layered heater according to  claim 10 , wherein the layered heater is selected from a group consisting of thick film, thin film, thermal spray, and sol-gel.  
   
   
       16 . The layered heater according to  claim 10 , wherein the resistive circuit pattern is selected from a group consisting of series, parallel, and series-parallel.  
   
   
       17 . The layered heater according to  claim 10 , wherein the variable thickness is continuous.  
   
   
       18 . The layered heater according to  claim 10 , wherein the variable thickness is non-continuous.  
   
   
       19 . The layered heater according to  claim 10 , wherein the resistive circuit pattern comprises a material having a variable composition.  
   
   
       20 . A layered heater comprising: 
 a resistive layer comprising a resistive circuit pattern, the resistive circuit pattern defining a trace having a length, a width, a thickness, and a spacing;    terminal pads in contact with the resistive layer adapted to connect the resistive layer to a power source; and    a protective layer formed on the resistive layer,    wherein the thickness of the resistive circuit pattern varies across the width of the trace of the resistive circuit pattern for a variable watt density.    
   
   
       21 . The layered heater according to  claim 19 , wherein the thickness of the resistive circuit varies along the length of the resistive circuit pattern.