Importance

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Abstract

An injection molding die apparatus for use in the production of an optical disk substrate has a stationary die part having a mirror-finished surface, a movable die part carrying a stamper, an outer peripheral ring slidably fitting on the outer periphery of the movable die part and contactable with the stationary die part when the movable die part has been moved close to the stationary die part, such that a die cavity to be charged with injected molten plastic is formed by the mirror surface of the stationary die part, the stamper and the outer peripheral ring. First and second ejection mechanisms are provided to push the injection-molded optical disk substrate away from the stamper simultaneously both at the central portion and outer peripheral portion of the optical disk substrate, while the optical disk substrate is held in close contact with the mirror-finished surface of the stationary die part, whereby the separation of the injection-molded optical disk substrate from the stamper takes place uniformly without distortion and failure in the transfer of the track grooves.

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First Claim