| 摘要 |
PURPOSE: To suppress the peak of mechanical resonance of a piezoelectric sufficiently by detecting the increment of current in the vicinity of resonance point thereof in order to protect a probe or the surface of a sample against damage when the probe strikes against the surface of the sample while quickening the response and regulating the voltage being applied to the piezoelectric by feeding the increment thus detected back to the piezoelectric. CONSTITUTION: A probe displacement detecting section 15 detects the displacement of probe in a cantilever 14 and delivers a displacement signal Sz to a Z displacement servo control section 16. The Z displacement servo control section 16 expands/contracts a tubular piezoelectric 13 by applying a Z control voltage Vz. A current (iz) flowing through the tubular piezoelectric 13 is detected by a current sensor 19 and differentiated by a differentiation circuit 20 thus determining an increment of current. A comparator 22 compares a correction voltage▵V, obtained by amplifying the increment of current through an amplifier circuit 21, with an applying voltage command delivered from the Z displacement servo control section 16 thus producing a voltage Vz being applied actually to the tubular piezoelectric 13.
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