Resistors for thermal flowmeters

Abstract

A resistor for a thermal type of flowmeter includes a ceramic substrate, a thin platinum film formed on the surface of the ceramic substrate, and lead wires for connecting the thin platinum film with an external circuit, and is located in a fluid to detect its flow rate. When the resistance value, R (.OMEGA.) , of the resistor for a thermal type of flowmeter is expressed in terms of a function of temperature, T (.degree.C.): R=R.sub.0 (1+.alpha.T+.beta.T.sup.2) where R.sub.0 is the resistance value in .OMEGA. of the resistor for a thermal type of flowmeter at 0.degree. C., .alpha. is the first-order term coefficient of the temperature coefficient of resistance, and .beta. is the second-order term coefficient of the temperature coefficient of resistance, the value of the first-order term coefficient, .alpha., of the temperature coefficient of resistance is at least 3,650 ppm/.degree.C. A deviation in the temperature coefficient of resistance can be effectively reduced or eliminated, making circuit regulation easier.

Dependencies are inferred from the claim text.