| 摘要 |
<p>PURPOSE:To facilitate circuit adjusting work by setting linear term alpha in the temperature coefficient of resistance at a specific value or above thereby suppressing fluctuation effectively. CONSTITUTION:A platinum thin film 22 is deposited by 0.2-1.5mum thick through sputtering on the outer surface of a ceramic pipe 21. Filming rate is set at 100Angstrom /min or below at that time. It is then heat treated at 700 deg.C or above and molded. Furthermore, the platinum thin film 22 is electrically connected with an external circuit through a lead wire 20 thus constituting a resistor for thermal flowmeter. Assuming R0 is the resistance of the resistor at 0 deg.C, alpha is linear term in the temperature coefficient of resistance, and beta is quadratic term, relationship between the resistance R and the temperature T deg.C can be represented by a formula R=R0(1+alphaT+betaT<2>), wherein the linear term alpha is set at about 3650ppm/ deg.C or above. Since output fluctuation of flowmeter due to the temperature of fluid is settled within + or -3%, electric circuit for temperature compensation requires no adjustment under high temperature.</p> |
