| 摘要 |
PURPOSE:To improve an S/N ratio and reliability while simplifying an arithmetic circuit, by providing a tapered part in the fluid passage of a detector, scanning numbers of couples of electrodes at the tapered part and detecting a flow rate, and thus detecting a low-range flow rate precisely. CONSTITUTION:A free-running counter CNT counts a clock CK repeatedly at some intervals and the switch of a multiplexer MP operates corresponding to the counting operation. Then, couples of electrodes are scanned successively to obtain an output based upon differential input components. The output passed through a differential amplifier increases as electrode couples A-A', B-B'- are selected successively. The output of the amplifier DA is applied to a comparator COMP and exceeds a reference voltage at some electrode couple to invert the polarity of the output. By a control signal CS during the inversion, a latch circuit LT latches a data signal DS from the counter CNT. The latched data is a counted value corresponding to the electrode couple of the counter CNT and therefore, the flow rate is known on an arithmetic display DP which generates and displays a flow rate signal corresponding to the electrode couple. |
