Matsushita Electric Industrial Co., Ltd.

Yasuhiro Sugihara

Mitsurou Moriya

Michiyoshi Nagashima

Shin-ichi Tanaka

Hiroshi Taniguchi

Hiromichi Ishibashi

Takeo Ohta

Shin-ichi Yamada

Yasuki Matsumoto

Shunji Oohara

Yoshito Dezaki

Yasukazu Nishino

Hiroyuki Andou

Kenzou Tatematsu

Tatsuo Seki

An optical recording medium is provided which includes a first substrate having a first information surface, a semitransparent reflection film formed on the first information surface of the first substrate, and a second substrate having a second information surface. In addition, the optical recording medium includes a reflection film formed on the second information surface of the second substrate, and an adhesive layer for adhering the first substrate and the second substrate so that the first information surface of the first substrate faces the second information surface on the second substrate. The thickness of the first substrate is the same as the thickness of the second substrate.

Optical recording medium having dual information surfaces

A reproduction apparatus is provided for reproducing information stored on an optical medium. The apparatus includes a light source for illuminating the optical medium, the optical medium having at least one surface containing information stored thereon; a focusing arrangement operable to focus the light source on the at least one surface containing information thereon; and a detection arrangement operable to detect the information stored on the optical medium. The optical medium includes a first substrate having a first information surface; a semitransparent reflection film formed on the first information surface of the first substrate; a second substrate having a second information surface; a reflection film formed on the second information surface of the second substrate; and an adhesive layer for adhering the first substrate and the second substrate so that the first information surface and the second information surface face each other, wherein the thickness of the first substrate is at least 0.56 mm, the thickness of the adhesive layer is at least 30 &#x3bc;m, the total thickness of the first substrate and the adhesive layer is in the range of 0.59 mm to 0.68 mm, and the adhesive layer includes a thermosetting material.

A reproduction apparatus is provided for reproducing information stored on an optical medium. The apparatus includes a light source for illuminating the optical medium, the optical medium having at least one surface containing information stored thereon; a focusing arrangement operable to focus the light source on the at least one surface containing information thereon; and a detection arrangement operable to detect the information stored on the optical medium. The optical medium includes a first substrate having a first information surface; a semitransparent reflection film formed on the first information surface of the first substrate; a second substrate having a second information surface; a reflection film formed on the second information surface of the second substrate; and an adhesive layer for adhering the first substrate and the second substrate so that the first information surface and the second information surface face each other, wherein the thickness of the first substrate is at least 0.56 mm, the thickness of the adhesive layer is at least 30 &#x3bc;m, the total thickness of the first substrate and the adhesive layer is in the range of 0.59 mm to 0.68 mm, and the adhesive layer includes an ultraviolet-curable material.

A reproduction apparatus is provided for reproducing information stored on an optical medium. The apparatus includes a light source for illuminating the optical medium, the optical medium having at least one surface containing information stored thereon; a focusing arrangement operable to focus the light source on the at least one surface containing information thereon; and a detection arrangement operable to detect the information stored on the optical medium. The optical medium includes a first substrate having a first information surface; a semitransparent reflection film formed on the first information surface of the first substrate; a second substrate having a second information surface; a reflection film formed on the second information surface of the second substrate; and an adhesive layer for adhering the first substrate and the second substrate so that the first information surface and the second information surface face each other, wherein the thickness of the first substrate is at least 0.56 mm, the thickness of the adhesive layer is at least 30 &#x3bc;m, the total thickness of the first substrate and the adhesive layer is in the range of 0.59 mm to 0.68 mm, and the reflection film includes aluminum.

A reproduction apparatus is provided for reproducing information stored on an optical medium. The apparatus includes a light source for illuminating the optical medium, the optical medium having at least one surface containing information stored thereon; a focusing arrangement operable to focus the light source on the at least one surface containing information thereon; and a detection arrangement operable to detect the information stored on the optical medium. The optical medium includes a first substrate having a first information surface; a semitransparent reflection film formed on the first information surface of the first substrate; a second substrate having a second information surface; a reflection film formed on the second information surface of the second substrate; and an adhesive layer for adhering the first substrate and the second substrate so that the first information surface and the second information surface face each other, wherein the thickness of the first substrate is at least 0.56 mm, the thickness of the adhesive layer is at least 30 &#x3bc;m, the total thickness of the first substrate and the adhesive layer is in the range of 0.59 mm to 0.68 mm, and the semitransparent reflection film includes gold.

The optical recording medium of this invention includes: a first substrate having a first information surface; a semitransparent reflection film formed on the first information surface of the first substrate; a second substrate having a second information surface; a reflection film formed on the second information surface of the second substrate; and an adhesive layer for adhering the first substrate and the second substrate so that the first information surface and the second information surface face each other, wherein the thickness of the first substrate is 0.56 mm or more, the thickness of the adhesive layer is 30 &mgr;m or more, and the total thickness of the first substrate and the adhesive layer is 0.68 mm or less.

The optical recording medium of this invention includes: a first substrate having a first information surface; a semitransparent reflection film formed on the first information surface of the first substrate; a second substrate having a second information surface; a reflection film formed on the second information surface of the second substrate; and an adhesive layer for adhering the first substrate and the second substrate-so that the first information surface and the second information surface face each other, wherein the thickness of the first substrate is 0.56 mm or more, the thickness of the adhesive layer is 30 &mgr;m or more, and the total thickness of the first substrate and the adhesive layer is 0.68 mm or less.

The optical recording medium of this invention includes: a first substrate having a first information surface; a semitransparent reflection film formed on the first information surface of the first substrate; a second substrate having a second information surface; a reflection film formed on the second information surface of the second substrate; and an adhesive layer for adhering the first substrate and the second substrate so that the first information surface and the second information surface face each other, wherein the thickness of the first substrate is 0.56 mm or more, the thickness of the adhesive layer is 30 .mu.m or more, and the total thickness of the first substrate and the adhesive layer is 0.68 mm or less.

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 includes a groove track and a land track provided on a resin substrate. Each of the tracks is divided into a plurality of sectors for every turn. Each sector has an ID region, a servo region, and an information region. A pit in the ID region is formed so as to span across both the groove track and the land track. The first wobble pit and the second wobble pit are provided on both sides of the center line of each track, and they are spaced with each other in the direction of the track. Thus, since a larger width of the pit can be provided, production of the optical recording medium can be facilitated. Moreover, since the center of the track can be detected accurately by the first and second wobble pits, accurate tracking control can be performed.

Optical disk capable of recording information on both groove and land

A facsimile bandwidth compression method using a facsimile signal comprising a synchronizing signal part, a control signal part having digital signals made by coding signals of existence or non-existence of substantial picture information in blocks which are made by dividing the picture information signal into a specified uniform length segment, and a picture information part consisting of picture information signal of the blocks containing at least one black picture element. A reference signal having an inverted carrier phase from that of the synchronizing signal part is inserted between the synchronizing signal part and the control part. The coding of the digital signal is made by inverting the carrier phase. Guard bands having specified levels are inserted between the blocks, thereby assuring more accurate and fine synchronization than the known WBS (white block skipping) art, and hence, a very clear reproduced picture.

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Katano, Japan

Yasuhiro Sugihara