| 摘要 |
PURPOSE:To realize erasing while carrying out reproduction and at the same time to obtain an effect equivalent to the rerecording after erasing, by carrying out the erasing by superposing a DC signal on a record information signal with the intensive light flux during the reproduction time and then reproducing these signals by performing fast forwarding until the information is detected. CONSTITUTION:The current of a power source 2 and modulated by a modulator 1 is applied to a semiconductor laser 3. The beams sent from the laser 3 are focused on a recording surface 6 via a half mirror 4 and a condenser lens 5, and the information is recorded on the surface 6 in the form of a change caused by heat. In the reproduction time, the current of the source 2 is reduced, and the reflected light given from the surface 6 is received at a photodetector 10 to be demodulated by a demodulator 11. For erasion, the current of the source 2 is increased and a DC signal is superposed on a record information signal to be recorded on the surface 6. In the reproduction time, an optical system 8 is quickly forwarded in direction A by a shifter 9 until the information is detected. In such way, erasing is possible while reproducing the part which is once recorded, and at the same time an effect equivalent to rerecording after erasing can be obtained. |
