| 摘要 |
PURPOSE:To make an emitter to be automatically subjected to strong flushing by automatically detecting the deterioration of the emitter, and making a timing signal for flushing to be produced. CONSTITUTION:A switch circuit 21 is usually opened, and any electric power is not supplied from a heat power-source 22 to an emitter 1. Signals proportional to probe currents are supplied to a divider 11 through amplifiers 10 and 15, while a signal representing the current of full discharged electrons is supplied to the divider 11 from the emitter 1. The output of the dividing circuit, together with the output of a function generator 18, is applied to a dividing circuit 16 as an input. When the output of the dividing circuit 16, which is supplied to a comparator 19, becomes below a standard voltage supplied from a reference power source 20, the comparator 19 sends a signal which works for subjecting the emitter 1 deteriorated to strong flushing. As a result, the switch circuit 21 is closed, and the emitter undergoes strong flushing by the heat current supplied from the heat power source 22. |
