| 摘要 |
PROBLEM TO BE SOLVED: To promote stabilization and high precision of electron beam scanning by stabilizing balance of positive and negative voltages impressed to a half bridge circuit that supplies a driving current to a scanning coil. SOLUTION: Between a positive electrode and a GND, and between the GND and a negative electrode of a direct current power supply 18, electrolytic capacitors 33, 34 are installed and±VCC/2 is impressed to the half bridge circuit 30 in a normal state. For example, if both end voltage of the electrolytic capacitor 33 is reduced and both end voltage of the electrolytic capacitor 34 is elevated, a current flows from the electrolytic capacitor 34 into a primary winding L1 of a transformer 42 when MOSFET 41 is turned on, and a current of the same voltage occurs in a secondary winding L2 with the same number of winding. Then, the current flows into the electric capacitor 33 via a reactor 43 and a diode 44, and the electrolytic capacitor 33 is charged. As a result, each of both end voltages of the electrolytic capacitors 33, 34 rapidly returns to VCC/2. COPYRIGHT: (C)2011,JPO&INPIT
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