Measuring and testing – Volume or rate of flow – Thermal type
Reexamination Certificate
2008-07-08
2008-07-08
Thompson, Jewel V (Department: 2855)
Measuring and testing
Volume or rate of flow
Thermal type
Reexamination Certificate
active
07395707
ABSTRACT:
A flow rate sensor has a problem that a resistance value of a heat generating resistor itself varies and sensor characteristics are changed during use of the sensor for a long term. Also, the temperature of the heat generating resistor must be adjusted on a circuit substrate with a resistance constituting one side of a fixed temperature difference control circuit, and this has been one of factors pushing up the production cost. All resistances used for fixed temperature difference control are formed on the same substrate as temperature sensitive resistors of the same material. This enables all the resistances for the fixed temperature difference control to be exposed to the same environmental conditions. Hence, even when the resistances change over time, the changes over time occur substantially at the same tendency. Since the resistances for the fixed temperature difference control change over time essentially at the same rate, a resulting output error is very small.
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Horie Junichi
Nakada Keiichi
Ueyama Kei
Watanabe Izumi
Yamada Masamichi
Hitachi , Ltd.
Hitachi Car Engineering Co. Ltd.
Mattingly ,Stanger ,Malur & Brundidge, P.C.
Thompson Jewel V
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