| 摘要 |
PURPOSE:To accurately perform the checking of bit formation at the same time of recording, by generating a small reference power at a constant ratio for a recording power just before the bit formation is performed, and comparing both powers at the level of reflected light from a medium plane. CONSTITUTION:A write reference signal (b) having a first prescribed pulse time width, and a write signal (c) having a second prescribed pulse time width from the rear edge of the signal (b) are generated. And to the write signal (c), a prescribed write current 12 capable of forming a bit is outputted as a driving current, and to the write reference signal (b), a reference current 11 not capable of forming the bit, and width the prescribed ratio is outputted as the driving current. Corresponding to the above outputs, an optical head generates an optical output, and projects on a recording medium 10, then, forms the bit, and also, detects the change of the intensity of the reflected light as an electrical signal, and a reproducing signal can be obtained. Furthermore, a difference between the reproducing signal and a reproducing reference signal obtained at a reproducing signal distribution circuit 12 is detected at a differential circuit, thereby, a reproducing differential signal can be obtained, and the level of the reproducing differential signal at a time when the bit is formed by the write signal is decided at a decision circuit, and the presence/absence of the bit formation can be checked.
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