HEAT SENSITIVE TYPE APPARATUS FOR MEASURING FLOW AMOUNT

摘要

PURPOSE:To enhance flow amount measuring accuracy as high as possible by increasing a dynamic range, by dropping output voltage from a bridge circuit by predetermined voltage before inputting the same to an A/D converter. CONSTITUTION:The current supplied from a control circuit corresponding to the flow amount of a fluid is flowing through the resistor R3 connected to a heat sensitive resistor RH in series and terminal voltage corresponding to said current (that is, corresponding to the flow amount of the fluid) is controlled by a shift-down circuit S. The shift-down circuit S outputs voltage obtained by subtracting predetermined voltage from terminal voltage and said output voltage is digitally converted by an A/D converter 1 to be inputted to an opera tion circuit (microcomputer) 2 which in turn operates the flow amount of the fluid on the basis of the inputted digital value.