Oval Corporation

Kenji Washio

Takashi Hirose

Noriaki Nakayama

Tetsushi Kitano

Yoshimine Tanabu

An instrumentation device having a pulse output function for preventing breakage of a switching element even if a wrong wire is connected. A calculation unit includes: a positive power supply terminal; a negative power supply terminal; a signal terminal; a control circuit; an NPN-type transistor; a feedback circuit; a PTC thermistor; and an N-channel type MOSFET. The NPN-type transistor has a collector terminal connected to the positive power supply terminal, an emitter terminal connected to the negative power supply terminal, and a base terminal connected to the control circuit. The PTC thermistor is a resettable protection element, and is connected in series to the signal terminal. The N-channel type MOSFET has a drain terminal connected to the signal terminal through the PTC thermistor, a source terminal connected to the negative power supply terminal on a downstream side of the feedback circuit, and a gate terminal connected to the control circuit.

Instrumentation device having pulse output function

A converter pulse width shaping circuit () according to the present invention is provided between a waveform shaping apparatus () and an erroneous output preventing apparatus () that are provided between a flow rate detecting portion () and a flow rate metering mechanism (). When high frequency pulse signals of a frequency not lower than a predetermined value are successively input, the converter pulse width shaping circuit () combines those high frequency pulse signals to convert them to a low frequency pulse signal, which is then output to the erroneous output preventing apparatus () having a low-cut function. In the present invention, a vortex flow meter is made up of a converter () including the converter pulse width shaping circuit () described above.

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Tokyo, Japan

Kenji Washio