| 摘要 |
PURPOSE:To improve output response with simple constitution by eliminating an electromagnetically induced noise voltage, an electrochemical DC noise voltage, and a commercial frequency noise voltage by energizing an electrode provided in a fluid to be measured by an alternating signal, and operating the electromotive force of the electrode. CONSTITUTION:Electrodes 3a and 3b cross the direction of a fluid to be measured, and an energizing coil 1 is at right angles to said fluid and each electrode fitting direction. Switches SW1-a, SW1-b, and SW2-a, and SW2-b change the polarities of feeding from a DC constant current source 16 to obtain a low frequency reactangular-wave energizing current. Each SW is controlled by a timing signal 17 from a signal processing circuit 18. The electromotive forces of the electrodes 3a and 3b are supplied through amplifiers 4 and 5 to the circuit 18, processed by A/D conversion 8 at timing from a CPU9, and stored in a memory 10; and the CPU9 performs arithmetic operation, and the arithmetic result is stored in the memory 10 and then processed by D/A conversion 12 to be outputted 15. Thus, a signal proportional to a flow rate is obtained. |
