Temperature detection and control system for layered heaters
A system for detecting and controlling temperature of a layered heater is provided that includes a layered heater having in one form a substrate, a first dielectric layer disposed on the substrate, a sensor layer disposed on the first dielectric layer, a second dielectric layer disposed on the sensor layer, a resistive heating layer disposed on the second dielectric layer, and a third dielectric layer disposed on the resistive heating layer. An overtemperature detection circuit is provided in one form that is operatively connected to the resistive heating layer. The circuit includes a resistor, the sensor layer, and an electromechanical relay in parallel with the sensor layer. The sensor layer defines a material having a relatively high TCR and the resistive heating layer defines a material having a relatively low TCR such that a response time of the control system is relatively fast.
1. A system for detecting and controlling temperature of a layered heater comprising:
a layered heater comprising:
a substrate;
a first dielectric layer disposed on the substrate;
a sensor layer disposed on the first dielectric layer, the sensor layer comprising a plurality of independently controllable zones;
a second dielectric layer disposed on the sensor layer;
a resistive heating layer disposed on the second dielectric layer; and
a third dielectric layer disposed on the resistive heating layer,
wherein the layered heater is formed by a process selected from the group consisting of thick film, thin film, thermal spraying, and sol-gel.
2. The system according to claim 1 , wherein the independently controllable zones of the sensor layer have the same size and are comprised of the same material.
3. The system according to claim 1 , wherein the plurality of independently controllable zones of the sensor layer are comprised of different materials.
4. The system according to claim 1 , wherein the sensor layer and the resistive heating layer further comprises tracks, the sensor layer tracks having a width Ws and the resistive heating layer tracks having a width Wr, such that Wr is greater than Ws;
wherein the sensor layer tracks cross the resistive heating layer tracks.
5. The system according to claim 4 , wherein the sensor layer tracks are oriented approximately perpendicular to the resistive heating layer tracks.
6. The system according to claim 4 , wherein W s is about 1 mm and W r is about 5 mm.
7. The system according to claim 4 , wherein the sensor layer tracks exhibit a voltage of about 12 V and an amperage of about 100 mA and the resistive heating layer tracks exhibit a voltage of about 230 VAC and an amperage of about 10 A.
8. The system according to claim 1 , wherein the sensor layer is formed of a material having a relatively high temperature coefficient of resistance (TCR) and the resistive heating layer is formed of a material having a relatively low TCR.
9. The system according to claim 8 , wherein the material that forms the sensor layer has a TCR of about 10,000 ppm/° C. and the material that forms the resistive heating layer has a TCR ranging from −10,000 ppm/° C. to about 1 ppm/° C.
10. The system according to claim 1 , wherein the first, second, and third dielectric layers exhibit a resistance that is 1×10 6 ohms or greater.
11. The system according to claim 1 , wherein the system further comprises an over temperature detection circuit operatively connected to the resistive heating layer; the over temperature detection circuit comprising:
a resistor or potentiometer;
the sensor layer; and
an electromechanical relay in parallel with the sensor layer.
12. A system for detecting and controlling temperature of a layered heater comprising:
a layered heater comprising:
a substrate;
a first dielectric layer disposed on the substrate;
a sensor layer disposed on the first dielectric layer, the sensor layer comprising a plurality of independently controllable zones and a plurality of sensor layer tracks;
a second dielectric layer disposed on the sensor layer;
a resistive heating layer disposed on the second dielectric layer, the resistive heating layer defining a plurality of resistive heating layer tracks; and
a third dielectric layer disposed on the resistive heating layer;
wherein the sensor layer tracks cross the resistive heating layer tracks and have a width that is narrower than a width of the resistive heater layer tracks,
wherein the layered heater is formed by a process selected from the group consisting of thick film, thin film, thermal spraying, and sol-gel.
13. The system according to claim 12 , wherein the sensor layer tracks are oriented approximately perpendicular to the resistive heating layer tracks.
14. The system according to claim 12 , wherein the sensor layer tracks have a width W s of about 1 mm and the resistive heating layer tracks have a width W r of about 5 mm.
15. The system according to claim 12 , wherein the sensor layer tracks exhibit a voltage of about 12 V and an amperage of about 100 mA and the resistive heating layer tracks exhibit a voltage of about 230 VAC and an amperage of about 10 A.
16. The system according to claim 12 , wherein the sensor layer is formed of a material having a relatively high temperature coefficient of resistance (TCR) and the resistive heating layer is formed of a material having a relatively low TCR.
17. The system according to claim 16 , wherein the material that forms the sensor layer has a TCR of about 10,000 ppm/° C. and the material that forms the resistive heating layer has a TCR ranging from −10,000 ppm/° C. to about 1 ppm/° C.
18. The system according to claim 12 , wherein the first, second, and third dielectric layers exhibit a resistance that is 1 ×10 6 ohms or greater.
19. The system according to claim 12 , wherein the system further comprises an over temperature detection circuit operatively connected to the resistive heating layer; the over temperature detection circuit comprising:
a resistor or potentiometer;
the sensor layer; and
an electromechanical relay in parallel with the sensor layer.
20. The system according to claim 12 , wherein sensor layer further defines a plurality of independently controllable zones that have the same size and are comprised of the same material.
21. The system according to claim 12 , wherein sensor layer further defines a plurality of independently controllable zones that are comprised of different materials.