| 摘要 |
PURPOSE:To enable the detection of the disconnection of a cathode during an activation process, by connecting the input light emission diode of a photocoupler in series with the cathodes of a plurality of electron tubes put in the activation process, and by finding out the change in the turn-on state of the output phototransistor of the photocoupler. CONSTITUTION:The cathode heaters 3 of a plurality of camera tubes or the like are connected in series with each other. Activation work is performed on the tubes as gas is being evacuated therefrom. Dividing diodes 4A-4C and a photocoupler 5 are connected in series with the cathode heaters 3. Prior to the activation work, a switch 1 is turned on to cause an electrical current to flow through the cathode heaters 3 so that the disconnection of the cathode heater can be detected in terms of the change in the turn-on state of the output phototransistor of the photocoupler 5. Electricity is then supplied from an activation feeder 9 to perform the activation work as it is found out by the photocoupler 5 likewise whether the cathode heater 3 is disconnected or not. If the disconnection of the cathode heater is detected, a warning circuit 8 in a control section located at a distance is put into operation through a detection circuit 7. The disconnection during the activation work is thus enabled to enhance productivity.
|
