Matsushita Electric Industrial Co., Ltd.

Nissei Plastic Industrial Co., Ltd.

Teichiku Co., Ltd.

Tokihalu Nakagawa

Nobuyuki Nakamura

Masaaki Sunohara

Shoji Ohmiya

Kaoru Yanagisawa

Shoji Omiya

Junnosuke Yamawaki

Seiji Inagaki

An upright injection-compression pressing machine for the manufacture of information carrier discs, such as photograph records and video discs, has a mold clamper assembly including a pair of stamper bearing molds movable relative to each other in a vertical direction towards and away from each other, and an injector assembly mounted on the clamper assembly in alignment with the direction of the relative movement of the molds.

Upright injection-compression pressing machine for the manufacture of

A method of producing a plate-shaped body, particularly a video disc in which circumferential warp in the thicknesswise direction, thickness fluctuation and deflection of the signal track are minimized comprising The steps of pressing by a mold a thermoplastic resin which has been heated to a temperature above the softening point thereof, and cooling the thermoplastic resin to solidify the same. During the cooling, the pressure of the mold is decreased to a low level when the thermoplastic resin has been cooled down to a temperature around the softening point. The thermoplastic resin is allowed to be solidified without any substantial and local residual stress to ensure minimal circumferential warp, thickness fluctuation and deflection signal track.

Method of producing plate-shaped body

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Hirakata, Japan

Tokihalu Nakagawa