| 摘要 |
PURPOSE:To attain an erasion whose previous history characteristic is good by making an erasing beam diameter larger than a write beam diameter in a track width direction of a recording medium. CONSTITUTION:An erasing beam diameter is made larger than a write beam diameter in a track width direction. A power density of a write beam is larger than a power density of an erasing beam, therefore, when a laser beam whose beam diameter is the same as that of the write beam is used as an erasing beam, the skirt part of the track width direction is not erased completely, a write state is left, therefore, the previous history characteristic does not become good. Accordingly, the erasing beam diameter is made larger than the write beam diameter in the track width direction. As a result, the previous history characteristic becomes good. The erasing beam is long in the track direction. It is desirable that its shape is elliptical or rectangular. |
