| 摘要 |
PURPOSE:To decrease loss electric power and to obtain satisfactory efficiency by connecting a focus coil and a heater in series in constant current of the focus coil and the heater or an image pickup tube of constant-voltage driving. CONSTITUTION:A heater 22 of an image pickup tube 19 and a focus coil 20 are connected in series, a current from a switching regulator 16 is supplied to the focus coil 20, and the current from the switching regulator 16 and the current from a switching requlator 17 are supplied to the heater 22. Therefore, the current which is supplied from the switching regulator 17 becomes I' h-I' f, and power consumption of the focus coil 20 and the heater 22 is decreased.
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