| 摘要 |
PURPOSE:To prevent the deterioration of a thin film due to oxidation by using a shut means so as to absorb the air freely flowing-in or out in a closed space due to the difference between a pressure in the closed space and an external pressure in a way of free contraction/expansion. CONSTITUTION:In order to apply transparent coating to a base 1, a material such as polychloride vinylidene or fluoride vinylidene is used and the coating is applied by the spin coat method. An air shut film 8 made of a flexible material having a shape like a baloon connected to a vent hole 7 is provided to the cavity 6 and the pressure difference generated between the space 4 and external air due to a temperature difference is absorbed in a way of free expansion/contraction. Thus, the number of cavities 6 is prepared in a range that the air shut film 8 absorbs the pressure difference of the space 4 absorbs sufficiently. Further, the air shut film 8 has a volume to absorb sufficiently the air volume flowing-out or in from the space 4 depending on the pressure difference generated within the operating temperature range of the optical disc and a type of material not penetrated with humidity is used. Thus, long service life of the optical information recording medium is attained. |
