Kabushiki Kaisha Toyota Chuo Kenkyusho

Akihiro Takeichi

Tomoyoshi Motohiro

Yasuhiko Takeda

Tatsuo Fukano

Naohiko Kato

In an optical disk which includes a recording film having a laminated construction, and which records information by changing optical characteristics of the recording film by applying a laser beam, there are laminatedly formed a WO film as a second layer, the WO requiring energy by about 470 kJ when it dissociates 1 mol of oxygen molecules, an Sn&mdash;43 atomic % Bi film which includes Sn as a first layer, the Sn generating energy by about 610 kJ when it bonds with 1 mol of oxygen molecules and having a melting point of about 139&deg; C., and a resin film in this order on a guide groove forming surface of a substrate When a recording laser beam is applied, a part of Sn&mdash;43 atomic % Bi film is turned into a liquid phase, both of the films and react, and the optical characteristics of the recording film vary so that information is recorded. As a result, the retention characteristic of the recorded data is secured, and the reactivity of the recording film is enhanced.

Storage member

A recording medium which includes a first substance and a second substance, wherein an external energy is applied to at least one of the first and second substances to react them in order to change the optical characteristics of the substances for recording information, the recording medium including: a first layer composed of a first substance including at least one of S and Se, a second layer composed of a second substance including a metal, and a barrier layer being disposed between the first and second layers, which allows the reaction between the first and second layers when laser beam for recording is irradiated as an external energy, and suppresses the reaction between the first and second layers when laser beam for recording is not irradiated. Alternatively, the recording medium can be free from the barrier layer, and the second substance can be arranged to have two or more compositionally different portions or two or more phases with a different crystalline state. Thus, when the external energy is not applied, the reaction between the first substance and the second substance is suppressed. Hence, the recording characteristics of the recording medium is inhibited from degrading.

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Aichi, Japan

Akihiro Takeichi