Patent ID: 6131463
Filing Date: 2000-10-17
Classification: F24F

Abstract:
Thermal sensing apparatus comprising a bridge differentially responsive to temperature changes in opposing legs of the bridge, said bridge comprising:a) first and second thermally-responsive Zener diodes disposed in said air path, the resistance of said diodes being variable with temperature, said diodes being connected by first and second respective electrical leads into opposing legs of said bridge, said first diode being a signal diode and said second diode being a reference diode, said diodes having first and second diode shields, respectively, said first and second diode shields being formed of metal and said first diode shield being connected to said first electrical lead to form therewith a heat sink for said first diode and a metal-induced heat-sink bias between said diodes; andc) first and second operational amplifiers in a feedback loop responsive to variations in electrical resistance of said first and second diodes to vary the voltage output signal of said bridge in proportion to the difference in resistance between said first and second diodes.