| 摘要 |
PURPOSE:To suppress the swelling-out of disc surface and consequently reduce the deterioration of electric characteristics due to the swelling-out by a method wherein disc just after compression-molded is left to stand in a specified atmosphere. CONSTITUTION:An electrostatic capacity conversion type information recording disc is left at rest in the dry state developed just after compression molding or in the atmosphere containing no moisture or in the atmosphere filled with alcohol. As a result, the deterioration of CNR of horizontal synchronizing signals, FM output of pre-amplifier, total time of drop-out and the like is suppressed. Especially, the effect of suppression appears remarkably when the disc is left at rest in the atmosphere of alcohol vapor. Furthermore, even if the disc is returned to the state left to stand in normal temperatures and humidities after the after-treatment, the treatment has hysteresis effect and consequently the degree of deterioration of electric characteristics in normal temperatures and humidities is reduced strikingly. Said hysteresis effect also appears prominently when the atmosphere of alcohol vapor is employed in the after-treatment. In other words, the atmosphere of alcohol vapor can suppress the swelling-out of disc surface, which is the main cause of the above-mentioned deterioration of the electric characteristics, to the utmost. |
