| 摘要 |
<P>PROBLEM TO BE SOLVED: To simplify a structure in a driving circuit for supplying drive current to a deflecting coil in order to two-dimensionally scan electron beams while achieving stability of its operation. Ž<P>SOLUTION: The drive current Id is supplied to a magnetic circuit section 16 including the deflecting coil 2 by a current negative feedback amplifier with one step of voltage amplification as an amplifying stage, and a dumping resistor R6 is connected with the deflecting coil 2 in parallel. A phase lag at a voltage amplifying section is 90° at its maximum, and the phase lag of the whole negative feedback loop does not reach 180° at its maximum since the phase lag at the magnetic circuit section 16 is smaller than 90°. Thus, the drive current can be stably controlled by preventing oscillation without adding a complicated phase compensation circuit. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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