Patent ID: 7292520

Claim:
A data recording and reproducing device comprising: a table for holding a recording medium having a phase-change type recording film; a cantilever having a probe and extending to locate a tip of the probe in the vicinity of the recording film; a Z driving unit that displaces the table or the cantilever in a Z direction vertical to the recording film; an X-Y driving unit that displaces the table or the cantilever in a X-Y direction in parallel to the recording film; a vibrator that vibrates the cantilever in a sense including the component in the Z direction; a displacement detector that detects the displacement due to vibration of the cantilever; a first frequency filter that derives a specific frequency component from a detected output from the displacement detector; a Z driving feedback circuit that controls the Z driving unit so that a distance between the central position of vibration movement of the probe and the recording film is maintained constant at a position where the probe is in slight contact with the recording film according to a magnitude of the specific frequency component; a write circuit that supplies a recording voltage to the cantilever in response to a recording signal; a voltage output circuit applies an AC voltage at a prescribed frequency to the cantilever; a second frequency filter that derives the frequency component at the prescribed frequency or its proximity; a voltage feedback circuit that changes a bias voltage to be applied to the cantilever so that a potential difference between a central potential of the probe and a surface potential at a scanning position of the recording film is maintained constant according to a magnitude of the frequency component derived from the second frequency filter, wherein a current is supplied to the recording film through the cantilever and the probe by the write circuit while the probe is moved along the surface of the recording film by the X-Y driving unit and Z driving unit and the Z driving feedback circuit so that the heat generated by the current causes a phase change in the region at a scanning position of the recording film, thereby recoding data, whereas the surface potential at the scanning position of the recording film is detected on the basis of the magnitude of the bias voltage which is changed by the voltage feedback circuit, thereby reproducing the data.