Pioneer Corporation

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Pioneer Electronic Corporation

Keiji Suga

Noriyoshi Shida

Tetsuya Iida

Kaoru Yamamoto

Tetsuya Imai

Atsushi Sato

Takanobu Higuchi

Kunitoshi Katagiri

Yasunobu Higashika

Kenichi Ishiguro

Preformatted areas in at least the most distal recording layer from an object lens among a plurality of recording layers in an optical disc include guard areas at both ends of the respective recording layer in the tracing direction. No data is recorded on the guard areas. The guard area length GL is determined to satisfy the following formula:&#xd7;()/[1&#x2212;()]where YL is a maximum allowable value of position deviation between the preformatted areas in the most distal recording layer and in another recording layer in the tracing direction; NA is the numerical aperture of the object lens; T is a distance between the most distal and the another recording layer; and 'n' is an refraction index of a medium between the most distal and the another recording layers.

Multi-layer optical recording medium and method of manufacturing the same

A conduction member having conduction path for injecting molten molding material within a mold space is fitted to one of a pair of mold bodies which form the disc-shaped mold space. A first heat suppressing member for suppressing heat within the conduction path from being transmitted to the one of the mold bodies is disposed between the conduction member and the one of the mold bodies. Further, a second heat suppressing member is disposed at a position opposite to the first heat suppressing member at the time of mold-clamping the pair of the mold bodies.

Mold for injection molding of disc substrate

In case of manufacturing a disk having a two-layer structure, a glass substrate is bonded to a cover layer through an adhesive layer , and a mount hole is formed in a center thereof to form a bonded substrate having a three-layer structure (a). In a state where a stamper formed a predetermined pit pattern is set to a center boss , the bonded substrate is pressed downward in a vertical direction while the mount hole of the bonded substrate is aligned with the center boss ( ). Whereby an information recording surface is transferred onto the cover layer ( ). Subsequently, after the bonded substrate has been bonded to another layer substrate of the disk, the adhesive layer is removed to separate the glass substrate . Finally, there is manufactured the disk having the two-layer structure.

Method of manufacturing a disk and transfer method for the disk

There are provided a disc-manufacturing mold capable of manufacturing a disc substrate having no irregularities in thickness in its circumferential direction and a disc manufacturing apparatus using the mold. The disc-manufacturing mold is used for forming a disc substrate by injection molding. A cooling water ditch is arranged on the mold. The cooling water ditch is configured such that a disc distorts substantially evenly in its circumferential direction when the disc is manufactured.

Disc-manufacturing mold and disc manufacturing apparatus using the same

An ultrasonic injection mold for an optical disk includes a movable die and a fixed die; a disk molding cavity formed between the movable die and the fixed die; a stamper positioned at the bottom of the cavity for forming a pit on a surface of the disk; and an ultrasonic generation device provided on the movable die or fixed die for applying ultrasonic waves to the cavity in performing infection molding. One or more slits are formed on the movable die and the fixed die in the direction which crosses the radial direction of the cavity. The ultrasonic injection mold minimizes the amplitude of the ultrasonic transmitted in the radial direction of the cavity.

Ultrasonic injection mold for an optical disk

A method for manufacturing a double-sided-multi-layered optical disc. An intermediate substrate having pits on both the major surfaces is previously prepared as well as first and second substrates. The method rotates the first substrate, the intermediate substrate and the second substrate with respect to the common center thereof so as to form unhardened radiation setting resin layers between adjacent substrates so that thicknesses of the unhardened resin layers are adjusted to predetermined values, and then the method irradiates a radiation onto the unhardened resin layer so as to harden the unhardened resin layers to solid resin layers.

Growing community of inventors

Tsurugashima, Japan

Keiji Suga