Recording and reading space control between a read/write probe and a recording medium

DETAILED DESCRIPTION The present invention has been made to solve the above-noted problems and has as its object the provision of a system which, in recording and reproduction to which the principle of STM is applied, stabilizes the control of the spacing between a probe electrode and a recording layer to thereby accomplish high information recording density and a high signal reading-out speed and enable re-writing to be stably effected even on a recording medium on which writing has already been effected.
In one aspect of the present invention which achieves the above object, in order to effect the reading-out of a signal from a recording medium at a high speed and without the collision of the probe electrode, the control of the spacing between the probe electrode and the signal recording layer is effected by sampling a tunnel current detected by the probe electrode at the timing of a reproduction clock, and reproduction is effected on the basis of this sampled value.
In another form of the present invention, in order to effect information recording with good reproducibility and at high density, the control variable of a servo control circuit for controlling the spacing between the probe electrode and the recording layer is changed over during the periods before and after a writing pulse is applied to the probe electrode.
In still another form of the present invention, in order to effect re-recording reliably, a prior recording state at a re-writing position is detected and from the result of this detection, an optimal servo control variable and the waveform of a pulse voltage applied are set.