Hitachi, Ltd.

Hitachi Maxell, Limited

Nippon Telegraph and Telephone Public Corporation

Babcock-Hitachi Kabushiki Kaisha

Hitachi Maxwell, Ltd.

Shinkichi Horigome

Motoyasu Terao

Tetsuya Nishida

Kazuo Shigematsu

Yasushi Miyauchi

Norio Ohta

Yoshinori Miyamura

Eiichi Maruyama

Yoshio Taniguchi

Akira Gotoh

Seiji Yonezawa

Hiroaki Miwa

Masahiro Ojima

Ryoichi Sudo

Yoshinori Imamura

Sachio Ishioka

Tetsuo Tajima

Hirokazu Matsubara

Munehisa Mitsuya

Keizo Kato

Sakae Ota

Ryo Suzuki

Toshimitsu Kaku

Makoto Kitoh

Yuichi Kokaku

Shuhei Nakamichi

Mitsuru Shimizu

Naoyuki Kikuchi

Yukinobu Yamazaki

Susumu Saito

Hiroyuki Suzuki

Tadashi Ikeda

Yutaka Sugita

Hideaki Yamamoto

Yumiko Anzai

Masaru Ito

Saburo Nonogaki

Hiroshi Shiraishi

Toshio Niihara

Yoshijiro Arikawa

Yoshiaki Mori

Yasuharu Shimomoto

Keiichi Kanehori

Masayuki Katsumoto

Yoshio Hatano

Shungo Sugawara

Yasuhiro Ohta

Horoyuki Suzuki

Mari Ichikawa

Akio Taniguchi

An information recording medium has a thin-film recording layer and a reflective layer that reflects a laser beam. The recording layer can be composed of an inorganic substance whose optical constant changes when exposed to a laser beam due to the change of its atomic arrangement. The recording layer can also be of an organic substance that deforms when exposed to a laser beam. The medium reflectivity, with respect to the reproduction laser beam exposure from the substrate side, is at least 65 percent on either of the recorded and unrecorded marks, and not more than 45 percent from the other of the recorded and unrecorded marks. In addition, the reflective-layer reflectivity, with respect to the reproduction laser beam, is at least 85 percent. The information recording medium additionally features excellent recording, erasing, and reproduction characteristics, with low recording power and high recording sensitivity during recording, and can even be read by a CD drive or the like.

Information recording medium comprising recording layer capable of

According to the present invention, etching is used to form a concave and convex pattern corresponding to information on an embossing metal mold comprising a conductive layer and a layer which includes an Ni electric-plating layer, or an Ni electric-plating layer, so that the surface of the embossing metal mold will not be contaminated even if processing conditions are somewhat changed, and that the mold will have less defects. Thus, optical disk substrates of high quality can be produced. Besides, time required for manufacturing a stamper can be shortened.

Embossing metal hold

In a process for producing optical disks comprising the steps of subjecting the photoresist layer on a substrate formed of silicon, quartz, glass or a metal to light exposure, developing and etching treatments to obtain a stamper and then duplicating an information pattern for an optical disk from the stamper obtained above to a transparent substrate by using a UV curable resin to prepare a replicated substrate of an optical disk, a large number of stampers can be prepared in a short time by conducting the light exposure either by contacting the mask side surface of a substrate provided with a photomask having an information pattern for an optical disk to the photoresist side surface of said substrate having the photoresist layer or by noncontact projection, and a rapid replication of large quantities of replicated substrates becomes possible by using a large number of stampers thus prepared.

Process for producing optical disks

An information recording medium which is superior in record/read-out characteristics, high in sensitivity and good in stability can be provided at a low cost by using, as an information-recording medium in which recording is carried out due to change in atomic arrangement upon irradiation with a laser beam, an information-recording medium comprising substrates 1, 1' , recording layers 2, 2' changing in atomic arrangement upon irradiation with a recording energy beam, and reflective layers which are provided contiguous to the recording layers and the recording layer has an average composition represented by A.sub.w D.sub.x Sb.sub.y Se.sub.z (wherein w, x, y and z are in the ranges of 0.ltoreq.w.ltoreq.30, 3.ltoreq.x.ltoreq.57, 3.ltoreq.y.ltoreq.57 and 40.ltoreq.z.ltoreq.90 in atomic percent, D represents at least one element of Sn, In, Ge, Pb, Si, Bi, Ga, Au, Ag and Cu and A represents an element other than Sb, Se, the elements represented by D and rare gases).

Information-recording medium

Disclosed herein is an information recording medium which is composed of a substrate, underlayer, and recording film and is capable of recording information by means of depressions or pits which are formed on the recording film upon irradiation with a recording energy beam, said information recording medium being characterized in that the recording film is provided with a supporting layer on at least one side of the recording film, said supporting layer having a melting point which is lower than that of the recording film, or on that side of the recording film which is adjacent to the substrate, said supporting layer having a melting point which is higher than that of the recording film. Owing to these features, the information recording medium gives recording pits having a smaller rim inner diameter, so that it achieves a high recording power margin for high-density recording.

Information recording medium

Disclosed are optical recording media having interposed an organic compound between a metal stamper and a transparent substrate and forming a replica onto which a signal surface formed on the metal stamper is transferrable to the transparent substrate.

Optical recording medium and method of manufacturing the same

By recording, reproducing and erasing information by using a recording thin film of the present invention, the information can be recorded, reproduced and erased by a single beam spot and new information can be rapidly rewritten while recorded information is erased. The irradiation beam is not limited to a light beam but it may be other energy beam such as electron beam or ion beam. The record medium is not limited to a disk but it may be tape or card and is applicable to a recording thin film other than the described thin film and to other methods. By using the described recording thin film, a manufacturing process is simple and reproducible, the recording/reproducing characteristic is high and the information can be stably stored for an extended time period. The record also may be rewritten a number of times.

Method for recording, reproducing and erasing information and thin film

An optical recording medium is made by sputtering a polymeric material in an evacuated chamber to form an under layer on a substrate having a preformed grooved pattern of prepits and pregrooves, and then forming a recording layer on the underlayer in the chamber continuously after forming the underlayer. Said under layer is made of a high polymeric material which can be melted, sublimated, or decomposed at a lower temperature than the melting point, the sublimating point, or the decomposing temperature of said recording layer. Accordingly, said under layer can relax the thermal shock transferred from said substrate into said recording layer, and the deformation of said substrate can be prevented, even though a laser beam for playback is repeatedly radiated onto said recording layer, and said optical recording medium has a larger recording sensitivity than the recording sensitivity of an optical recording disc of a prior art.

Method for producing an optical recording medium

An information recording thin film capable of changing an atomic configuration upon exposure to a recording beam, formed on a substrate directly or through a protective layer composed of at least one of inorganic materials and organic materials, an average composition in the film thickness direction of the information-recording thin film being represented by the following general formula;

Information recording thin film and method for recording information

In an optical recording medium, an under layer is formed between an even pattern of a substrate and a recording layer, and said under layer is made of a high polymeric material which can be melted, sublimated, or decomposed at a lower temperature than the melting point, the sublimating point, or the decomposing temperature of said recording layer. Accordingly, said under layer can relax the thermal shock transferred from said substrate into said recording layer, and the deformation of said substrate can be prevented, even through a laser beam for playback is repeatedly radiated onto said recording layer, and said optical recording medium has a larger recording sensitivity than the recording sensitivity of an optical recording disc of a prior art.

Optical recording medium and production method thereof

In an optical recording disk wherein a resin layer cured with ultraviolet radiation is provided on a surface of a transparent substrate, the present invention consists in that a material having a heat distortion temperature of at least 65.degree. C. is employed for the ultraviolet-cured resin layer. The appearance of wrinkles on a UV-cured resin surface is suppressed, whereby an optical recording disk of high carrier-to-noise ratio and long lifetime can be provided.

Optical recording disk

An information-recording thin film provided on a substrate directly or through a protective layer has an average composition of the thin film being represented by the general formula;

Information-recording thin film and method for recording and reproducing

An optical disc wherein a transparent base plate is made from a special light-curable resin composition comprising at least one compound of the formula: ##STR1## wherein R.sub.1 =H or methyl and n=0-5, and a photopolymerization initiator, is excellent in heat resistance, mechanical strength, moisture resistance, etc.

Optical disc

An electron beam memory system in which a phase transition type recording film is used as an information recording medium, and for recording information, a focused electron beam is selectively projected on desired positions of the recording film so as to locally heat the recording film and cause phase transition, while for retrieving information, an electron beam having energy at a degree not causing the phase transition is projected so as to utilize the fact that reflection or diffraction of the primary electron beam projected at the retrieval differs between the recorded regions and unrecorded regions.

Apparatus for storing and retrieving information using an electron beam

In an information recording apparatus according to this invention, since it is not necessary to dispose any differential circuit, which was required heretofore, it is possible to fabricate it with a low cost and its error rate is also very small. Furthermore, since the mean reflectivity on the recording track does almost not vary by the fact that information is recorded there, no tracking off-set or focusing off-set is produced. Thus effects of this invention are remarkable.

Information recording apparatus for recording/reproducing information by

Growing community of inventors

Tachikawa, Japan

Shinkichi Horigome