| 摘要 |
PURPOSE:To correctly read out data bits with an optical disk device, in which the time interval between data bits ''1'' and ''1'' irregularly changes, by specifying the irradiating time of an optical beam. CONSTITUTION:Data bits ''0'' are irregularly inserted between data bits ''1'' and ''1'' and a pulse interval variable circuit 9 makes control so that the recording waveform can always have a duty factor 50% at the time of insertion. That is to say, the light emission of a laser 11 is started at the rise of the data bit ''1'' and a ''0'' continuity discriminating circuit 8 discriminates the cycle up to the rise of the next data ''1'', and then, the light emission is stopped after the time of a half cycle has passed. When using such bits, the ratio of the area of a pit (d) to the area (e) where no pit (d) is formed becomes 1:1. Since the pit (d) is largely formed at the section where the data bit ''0'' is inserted in a plural number, the waveform (3) of a readout signal is saturated. Therefore, a Vp.p level (a) can be detected and decision of a 1/2-Vp.p level (b) also becomes possible. |
