Protected optical disk of welded construction

摘要

A protected optical disk of welded construction comprises a housing the diameter of which is its largest dimension. The housing consists of parts fabricated from a thermoplastic material joined together by at least one circular weld which occupies part of a plane annular joining area perpendicular to the axis of rotation of the disk. An internal chamber is bordered radially by this joining area. An information carrying layer is contained in this chamber. A pair of grooves lies one on either side of the portion of each of the parts included in the weld and there is a circularly disposed sharp edged projection between the grooves of each pair. In this way the grooves and the projection form a weld preform on at least one joining surface of the parts.