| 摘要 |
PURPOSE:To obtain the coincidence between a target surface and a focusing surface with no increment of electric power and then to apply the dynamic focusing, by varying the AC deflecting voltages applied to a pair of deflecting electrodes adversely to each other and then varying the apparent DC deflecting voltage. CONSTITUTION:An electromagnetic focusing coil 10 is provided to a deflection focusing system of an MS type image pickup tube, and a focusing DC power supply 11 which generates a DC magnetic field is provided to the coil 10. At the same time, a DC voltage power supply 14 for deflecting electrode is provided to apply the DC voltage in common to a pair of horizontal deflecting electrodes 12 and 12' as well as vertical deflecting electrodes 13 and 13'. Then AC deflection power supplies 15 and 15' for horizontal deflection and a modulating means 17 are provided to a pair of electrodes 12 and 12', and AC deflection power supplies 16 and 16' for vertical deflection and a modulating means 18 are provided to a pair of electrodes 13 and 13'. For the AC deflecting voltages applied to paired electrodes 12 and 12' as well as 13 and 13', horizontal sawtooth waves (a) and (b) and vertical sawtooth waves (c) and (d) are set opposite to eath other by means of the modulating means 17 and 18. Thus the coincidence is obtained between a target surface and a focusing surface with no increment of electric power by these deflecting voltages changing adversely to each other. |
