Emi, LLC

David E Birt

Lyn Holt

Peter J Clarke

An apparatus, for use in an electroplating arrangement, for establishing electrical contact with a metal or metalized cathode plate used in production of a disc record matrix. The apparatus includes an electrically conductive contact member and a clamping means for holding the contact member against a cathode plate supported by the apparatus. The contact member and clamping means are shaped so that electrical contact is established at the periphery only of the cathode plate.

Record matrix preparation

A two stage moulding procedure for the production of foil video discs. In a first pressing operation a satin finish consisting of a surface irregularity is applied to a surface of the foil, and then, in a second pressing operation, the foil is pressed between stamper plates to impart thereto, at one or both surfaces an impression of the information or data to be recorded. The satin finish may be formed by pressing the foil between stamper plates bearing the satin finish at their inwardly facing surfaces or alternatively between a pair of rollers bearing the satin finish at their surfaces.

Foil video discs

A record having an information track cut into the surface and a visible pattern formed on surface 'lands' bordering the track. The pattern is shallower than the track depth, typically 0.7 micron for a 25 micron sound microgroove record track. A method of providing the marking by applying solvent to a lacquer before cutting a master is described.

Disc records having surface markings

A means for moulding thermoplastics video discs having one or two shaped resilient compensators to maintain the stamper plates in parallelism with the plastics foil during moulding. The compensators may be of a rubber and may contain a thermally conductive material.

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London, United Kingdom

David E Birt