Overcoat structure for optical video disc
US4101907A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 29, 1977 |
| Grant date | Jul 18, 1978 |
| Priority date | — |
| Expiry date | Aug 29, 1997 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11B2007/25715
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An optical recording medium comprises a light reflecting material coated with a light absorbing material which is coated with a transparent barrier layer and overcoated with a relatively thick transparent protective layer. During recording, portions of the light absorbing layer are ablated by a modulated focussed light beam, thereby exposing portions of the reflecting layer while leaving the barrier and overcoat layers intact. Information is recorded in the form of a reflective-antireflective pattern. The overcoat layer suspends dust particles far above the focal plane of the recording lens, thereby reducing their effect on the recording or playback signal. The barrier layer insulates the light absorbing layer and the overcoat layer from chemical and thermal interactions which might result in a decreased signal-to-noise ratio.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.