| 摘要 |
PURPOSE:To improve responsiveness by comparing an emission current detecting value with a reference value and controlling the ON/OFF of filament current based on a compared output. CONSTITUTION:A triode type ionization vacuum gage 10 in an emission control device is constituted of a filament 11, a glid 12 and a collector 13. An ion current measuring circuit 14 is connected to the collector 13 and a constant voltage circuit 15 is connected to the glid 12. On the other hand, power is supplied from a power source 21 to the filament 11 through a power transistor Q1 and a switch 22. The emission current is detected by a resistor R4. In addition, a Schmitt circuit consisting of an operational amplifier 23 and a reference voltage power source 24, a photocoupler 25 and an abnormality detecting circuit 26 are also arranged in the device. Thus, the detecting value is compared with the reference value to control the ON/OFF of current through the filament. |
