| 摘要 |
PURPOSE:To allow always exact reproduction in spite of a change with age by providing a control adjustment region and finely adjusting a control means at the time of reproducing this control adjustment region. CONSTITUTION:The control adjustment region 51 is provided in addition to a signal region 52 where image and data are recorded on the recording medium. The control means, such as focus control or tracking control of a laser, is nearly most adequately adjusted. The always adequate reproduction of the signal region is, therefore, possible as well. An optimum state is obtd. in some cases when a control error signal is deliberately deviated from zero. The deviation quantity from the zero is designated as (d), then the exact reproduction of the image signal, etc., is possible if the laser spot position is so controlled that the control error signal attains (d) in a control circuit even at the time of reproducing the region 52. The always exact reproduction is possible in this way in spite of the change with age. |
