Optical disc unit, fabrication method and cooperating write and/or read apparatus

For use with optical disc appartus of the kind adapted for the optical writing and/or reading of high density information and including a rotatable receiving means having a reference surface which is rotatable about an axis in a first plane that is normal to said axis and lens means for focusing write and/or read light at a focal plane parallel to said first plane, an optical disc-unit comprising:

• (a) an optical disc including a flexible, disc-shaped support carrying a record layer;
• (b) a disc cover opposing said record layer and comprising a flexible, disc-shaped sheet which is substantially transparent to writing and/or reading wavelengths and which is generally coextensive with said optical disc;
• and
• (c) annular retaining means, engaging said support and said sheet around their peripheral regions, for positioning the sheet and the record area of the support in spaced relation, said retaining means including an index surface adapted to predeterminedly position said unit on the reference surface of such apparatus receiving means with said record layer proximate such apparatus focal plane.

In optical disc write and/or read apparatus of the kind including:

• (i) optical disc-unit receiving means having a reference surface, which is rotatable about an axis in a first plane that is substantially normal to said axis, and (ii) lens means for focusing write and/or read light at a focal zone generally parallel to said first plane, an improved optical disc-unit comprising:
• (a) an optical disc including a continuous, flexible, disc-shaped support carrying a record layer;
• (b) a disc cover opposing said record layer and comprising a continuous, flexible, disc-shaped sheet which is optically transparent to such writing and/or reading light and which is generally coextensive with said optical disc;
• and
• (c) annular retaining means having index surface means contacting said reference surface and means, engaging each of said disc-shaped support and said disc-shaped sheet substantially continuously around respective annular peripheral regions, for positioning said sheet and the record portion of said layer in a spaced relation;
• said index surface means being predeterminedly located with respect to said support and said reference surface being predeterminedly located relative to said focal zone so that said record layer is proximate said focal zone.

Optical disc write and/or read apparatus adapted for use with an optical disc-unit of the kind including:

• (i) an optical disc having a continuous, flexible, disc-shaped support carrying a record layer and (ii) annular retaining means having index surface means and means for engaging said support substantially continuously around an annular peripheral region so as to urge said support into a generally flat condition, said apparatus comprising:
• (a) receiving means having a reference surface which is rotatable about an axis generally within a first plane that is normal to said axis;
• and
• (b) lens means for focusing write and/or read light generally at a focal zone that is generally parallel to said first plane,
• said first plane being predeterminedly located with respect to said focal zone so that when the index surface means of a received disc-unit contacts said reference surface, the support of such disc-unit is located proximate the focal zone of said lens.

A method of fabricating an optical disc-unit adapted for optical writing and/or reading of high density information, said method comprising the steps of:

• (a) forming an optical disc including a continuous, flexible, disc-shaped support carrying a record layer;
• (b) forming a disc cover including a continuous, flexible, disc-shaped sheet which is substantially transparent to writing and/or reading wavelengths and of diameter generally equal to said optical disc;
• (c) forming first, intermediate and third annular retaining members of diameter generally equal to said optical disc, said first and intermediate members having cooperative rib and groove portions in radially inward surfaces thereof and said intermediate and third members having cooperative rib and groove portions in radially inward surfaces thereof;
• (d) placing said first, intermediate and third members in opposing relation with respective groove and rib portions aligned for interfitting cooperation and with peripheral regions of said support and sheet interleaved therebetween;
• and
• (e) manipulating said members into interfitting relation so as to dispose unretained portions of said support and said sheet in cylindrically symmetric tension.