Matsushita Electric Industrial Co., Ltd.

Takeo Ohta

Shigeaki Furukawa

Kazumi Yoshioka

Katsumi Kawahara

Tetsuya Akiyama

Masami Uchida

Nobuo Akahira

Tatsushi Nakamura

Hidemi Isomura

Tadaoki Yamashita

Noboru Yamada

Mutsuo Takenaga

Kenichi Nishiuchi

Hiromichi Ishibashi

Koichi Kotera

Seiji Nishino

Mitsurou Moriya

Kenji Narumi

Kazuo Inoue

Michiyoshi Nagashima

Ken'ichi Nagata

Takashi Hirao

Kiyotaka Wasa

Tomio Yoshida

Hideki Kitaura

Yasuhiro Sugihara

Keiichiro Horai

Shizuhiko Tanigawa

Kunihiro Matsubara

Atsuo Nishikawa

An edge position of a recording pulse is corrected according to multi-valued information for determining the width of a mark in an edge position correction circuit, thereby it is possible to form a mark edge in a correct position when a mark with any width is to be corrected to enable a correct multi-valued recording/reproducing.

Optical information recording method, optical information recording device and optical information recording medium

A multivalued information recording method in which energy applied to information units on a recording medium is varied to record multivalued information. In accordance with a relationship between the multivalued information in a predetermined information unit and the multivalued information in information units adjacent to the predetermined information unit, the energy applied to the predetermined information unit is decided.

Multivalued information recording method, multivalued information recording apparatus, and recording medium

An optical recording medium capable of recording reproducing and erasing information wherein a pulsating phenomenon where dielectric layer provided on the top and bottom of the recording thing film layer are thermally expanded, and contracted through the recording.erasing so that an inferior phenomenon of moving the recording thin film layer along the guiding groove in the disc rotating direction is considerably restrained, whereby, uneven thickness in the recording thin film layer is removed, thus making it possible to prevent the signal quality from being deteriorated, and the repeating characteristics of the recording.erasing operations are exceptionally improved.

Optical recording medium

On a substrate, a recording layer which reversibly transforms between two states with different optical properties--a crystalline phase and an amorphous phase--by the irradiation of a laser beam, a first and a second dielectric layer on the bottom and the top surfaces of the recording layer, and a third dielectric layer on one surface of the first or the second dielectric layers and on the opposite side with respect to the recording layer are successively laminated, thus preparing an optical information recording medium. The third dielectric layer has a smaller coefficient of thermal expansion than the first and the second dielectric layers, so that the thermal deformation of the first and the second dielectric layers is reduced and the mass transfer of the recording layer is controlled. As a result, the overwrite cycle characteristics of the optical information recording medium are excellent.

Optical information recording medium

On one surface of a disk substrate, a first dielectric layer, a thin recording layer, a second dielectric layer and a reflecting layer are cumulatively formed. The second dielectric layer is thinner than the first dielectric layer and is 35-70 nm thick. The reflecting layer is 70-120 nm thick. The total thickness of the four layers is 250-430 nm. The compressive stress of the layers is offset by tensile stress generated by an overcoat resin protective layer, formed on the reflecting layer. A method of using the optical recording medium applies the MCAV (Modified Constant Angular Velocity) recording method which records information by changing recording frequencies in accordance with linear velocity. The linear velocity is 5-12 m/s. A ratio of an inner circumference recording pulse width to an outer circumference recording pulse width is 1.2 or more.

Method of recording information

On one surface of a disk substrate, a first dielectric layer, a thin recording layer, a second dielectric layer and a reflecting layer are cumulatively formed. The second dielectric layer is thinner than the first dielectric layer and is 35-70 nm thick. The reflecting layer is 70-120 nm thick. The total thickness of the four layers is 250-430 nm. The compressire stress of the layers is offset by tensile stress generated by an overcoat resin protective layer, formed on the reflecting layer. A method of using the optical recording medium applies the MCAV (Modified Constant Angular Velocity) recording method which records information by changing recording frequencies in accordance with linear velocity. The linear velocity is 5-12 m/s. A ratio of an inner circumference recording pulse width to an outer circumference recording pulse width is 1.2 or more.

A record medium according to the present invention includes a substrate having concave or convex information pits and a thermosensitive material film formed on the substrate. The thermosensitive material film is changed from a high reflectance state to a low reflectance state when its temperature becomes a high level and returns to the high reflectance state when its temperature decreases to a low level. In the case where information is reproduced, when a light beam having a predetermined power is irradiated to the record medium, heat generated by the light beam is confined in the pits and the temperature in the pits increases; the thermosensitive material on the pits becomes the low reflectance state. The flat portions between the pits has high heat radiation and thus, the temperature in the flat portions does not increase so much; therefore, the state of the thermosensitive material film on the flat portions is not changed. Thus, an optical power of reflected light from the pits to which a light beam is irradiated is decreased, so that an amplitude of a reproduced signal is increased.

Optical reproducing device, optical reproducing method using the same,

An optical recording medium capable of recording, reproducing and erasing information wherein a pulsating phenomenon where dielectric layer provided on the top and bottom of the recording thing film layer are thermally expanded, and contracted through the recording and erasing so that an inferior phenomenon of moving the recording thin film layer along the guiding groove in the disc rotating direction is considerably restrained, whereby, uneven thickness in the recording thin film layer is removed, thus making it possible to prevent the signal quality from being deteriorated, and the repeating characteristics of the recording and erasing operations are exceptionally improved.

A reflecting film for use in an optical recording medium, which essentially consists of gold. The reflecting film also is capable of including a second reflecting layer essentially made of aluminum. An optical recording medium includes a recording film, the reflecting layer(s), an adhesive layer, and a cover layer for covering a surface of the adhesive layer, which are formed on one surface of a transparent substrate in this order.

Optical recording medium and reflecting film for use therein

In a record medium wherein information is recorded and/or erased by changing the optical state thermally by the irradiation with a laser beam or the like, a protection layer made from a material having a larger thermal conductivity than adjacent protection layers is used to decrease the temperature difference between the center and edges of a record mark on recording and/or erasing with a laser beam. By using the material having a larger thermal conductivity, the heat due to the irradiation with a laser beam or the like is diffused not only to the periphery of the substrate, but also to the plane of the substrate surely. Therefore, the temperature difference between the center and the edges in a mark on irradiation with the laser beam is decreased, and the recording/erasing characteristics and the power margin for erasing can be improved.

Optical record medium

A phase change type information storage disk in which a reflective layer is formed of an alloy thin film comprising as a main component any one of Ni--Cr, Cr or Ti and a metal having a larger malleability than said main component, being easy to be initialized and strong to thermal shock.

Information storage disk employing a reflective layer having good

An optical information recording medium is disclosed in which the recording layer is a material capable of absorbing energy and being reversibly converted between a substantially non-crystalline or amorphous state and a substantially crystalline state. The recording layer is a Te-Ge-Sb composition which also contains nitrogen. The optical recording medium includes a substrate onto which is sequentially deposited a first dielectric layer, a nitrogen-containing recording layer, a second dielectric layer and a metallic reflecting layer. In order to control the sensitivity of the medium to laser irradiation, the second dielectric layer is graded in thickness and progressively becomes thicker as a function of increasing radius. Alternatively, in another embodiment, the reflecting layer is graded in thickness, and progressively becomes thinner as a function of increasing radius. To further optimize the write/erase characteristics, the write to erase power ratio, as well as the recording duty cycle of the laser are varied as a function of radial position.

Method of recording and erasing information in an erasible optical

An optical information recording medium is provided in which the active layer is a phase change material capable of absorbing energy and being converted between a substantially amorphous state and a substantially crystalline state. The active layer contains nitrogen, which may be in the form of a nitride or nitrides of the constituent elements of the active layer, or may be a nitrided surface thereof. The inclusion of nitrogen inhibits localized shifting of the active material, which leads to degradation of the recording/erase properties of the medium. The optical recording medium includes a substrate, onto which is deposited in sequence a first dielectric layer, a nitrogen-containing active layer, a second dielectric layer, and a metallic reflecting layer. The second dielectric layer is made thin, so that the cooling rate of the active layer is increased to form a more uniform amorphous state.

Optical recording medium and production process for the medium

Disclosed is an optical information recording medium which comprises an active layer which undergoes phase change upon irradiation with light and protective layers formed on both the sides of the active layer, wherein the thermal capacity of the active layer which is a heat source is decreased, a reflection layer of high thermal conductivity is provided on the protective layer to cause increase of the coefficient of lines expansion of the protective layer with increase in distance from the active layer or the thickness of each layer is specified to make nearly the constant maximum temperature by irradiated light against a change in the thickness of the active layer.

A method of depositing the layers of an optical recording medium to their requisite thicknesses is disclosed in which optical monitoring of the reflectivity of a first dielectric layer during deposition is used to determine the deposition rate. The reflectivity is monitored to determine the time period in which the reflectivity reaches a maximum or minimum value, which occurs when the layer is a quarter wave thick. The deposition rate is derived from that time period, and the deposition is continued for a time in accordance with the deposition rate until the requisite thickness of the first dielectric layer is obtained. The second dielectric layer is deposited for a lesser time period in accordance with the deposition rate which has been optically derived during deposition of the first dielectric layer.

Growing community of inventors

Nara, Japan

Takeo Ohta