Optical disc pressure-collapsible cover
First Claim
1. An optically readable information storage disc comprising a transparent disc-shaped substrate, a recording layer disposed on the substrate, said layer being locally modifiable by a beam of radiation, and a cover disc secured to said substrate in a substantially gas-tight manner and having a portion which is spaced from at least that part of said recording layer on which information is to be recorded so as to form a sealed space therebetween, said cover disc being sufficiently flexible so that its resistance to deformations due to differences between gas pressure in said sealed space and ambient barometric pressure is substantially lower than that of said substrate so as to reduce deformations of said substrate due to said pressure differences.
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Accused Products
Abstract
An optically readable storage disc comprises a transparent substrate 1 on which a recording layer 2 is deposited which can be modified locally by means of a radiation beam, which recording layer is covered by a cover disc 3 which is secured to the substrate in a gas-tight manner at some distance from the part of the recording layer which is intended for recording, so that a sealed space 4 is enclosed between the substrate 1 and the cover disc 3. The cover disc 3 will be deformed to the greatest extent under the influence of differences between the gas pressure in the sealed space 4 and the barometric pressure because its resistance to deformation is substantially smaller, so that deformation of the substrate 1 is substantially precluded.
24 Citations
5 Claims
- 1. An optically readable information storage disc comprising a transparent disc-shaped substrate, a recording layer disposed on the substrate, said layer being locally modifiable by a beam of radiation, and a cover disc secured to said substrate in a substantially gas-tight manner and having a portion which is spaced from at least that part of said recording layer on which information is to be recorded so as to form a sealed space therebetween, said cover disc being sufficiently flexible so that its resistance to deformations due to differences between gas pressure in said sealed space and ambient barometric pressure is substantially lower than that of said substrate so as to reduce deformations of said substrate due to said pressure differences.
Specification