Multiple pressing matrix - for sound or video recording using capitals etc thermoplastic sheet

摘要

The invidual tracks are engraved on a lacquered foil which is then electroplated to form the matrix. The pressure plates used in the press. have a number of annular raised plane sections corresponding exactly to the positions of the engraved tracks on the foil so that during pressing the heat and pressure are applied only to those parts of the blank sheet material at which the grooved tracks are to be formed. Esp. for small recorded discs e.g. less than 17.5 cm dia. Economy in prodn. and ease of accurate centring of spindle holes.