Abstract: An optical information medium comprises a pair of discs which are bonded to each other, an optical recording layer provided on at least one of the discs, and a reflecting layer formed on an upper side of the optical recording layer. The optical information medium further includes an adhesive for bonding the pair of discs provided on the reflecting layer, wherein the adhesive has a thickness ranging from 10 to 80 ?m. A protecting layer is provided on the upper side of the reflecting layer wherein the pair of discs may be bonded by the protecting layer. The optical recording layer, reflecting layer and protecting layer may be directly sequentially provided on the disc but another substrate layer may be inserted between these layers. There is employed, as the adhesive, those including a reactive curing resin or a hot melt material, and it is preferable that the shrinkage rate of the adhesive be less than 15%.

Abstract: An optical information medium made up of a transparent substrate capable of allowing a recording laser beam to penetrate therethrough; a recording layer formed on the transparent substrate; and a reflective layer formed on the recording layer and reflecting a reproducing laser beam thereupon. A numerical aperture of an objective lens of an optical pickup for irradiating the recording laser beam on the recording layer is approximately 0.65, and the numerical aperture of an objective lens of the optical pickup for irradiating the recording laser beam on the reflection layer is approximately 0.60. An inclination angle &thgr; at both edges of the groove for tracking, being formed spirally on the surface of the transparent substrate on which the recording layer is formed, with respect to the main surface of the transparent substrate, is selected to be from 55° to 75°.

Abstract: An optical information recording medium enables accurate tracking servo throughout the recording area including inner and outer peripheral region by way of reducing the differences between the amplitudes of the push-pull signals from those regions. The medium comprises a light transmitting substrate, a tracking groove formed on a surface of the light transmitting substrate, a recording layer formed on the surface of the substrate having the groove, and a reflective layer, formed on the recording layer, for reflecting recording and reproducing laser beams. The width of the groove at the outer peripheral region is made smaller than that at the inner peripheral region. Specifically, the ratio of the width at the outer peripheral region to that at the inner peripheral region is set to be greater than or equal to 0.8.

Abstract: An optical information recording medium provides a high reflectance of a laser beam and thus enables an accurate tracking servo. The optical information recording medium, for recording optically readable signals thereon through the use of a recording laser beam, includes a light transmitting substrate, a tracking groove formed on a surface of the light transmitting substrate, a land formed between two neighboring tracks of the tracking groove, a recording layer formed on a surface of the light transmitting substrate on which the tracking groove and the land are provided, and a reflective layer formed on the recording layer for reflecting the recording laser beam. A top width D of the land is arranged to be within the range of about 0.30≦D≦0.45 &mgr;m.

Abstract: An optical information medium comprises a pair of discs which are bonded to each other, an optical recording layer provided on at least one of the discs, a reflecting layer formed on an upper side of the optical recording layer. The optical information medium further includes an adhesive for bonding the pair of discs provided on the reflecting layer, wherein the adhesive has a thickness ranging from 10 to 80 &mgr;m. A protecting layer is provided on the upper side of the reflecting layer wherein the pair of discs may be bonded by the protecting layer. The optical recording layer, reflecting layer and protecting layer may be directly sequentially provided on the disc but another substrate layer may be inserted between these layers. There is employed, as the adhesive, that including a reactive curing resin or a hot melt material, and it is preferable that the shrinkage rate of the adhesive be less than 15%.

Abstract: Provided is a medium for recording optical information and a method for recording optical information that allow recording sensitivity to be increased, and particularly a prescribed recording sensitivity to be maintained together with reflectivity and other playback characteristics during high-speed recording, by employing the temperature dependence of recording sensitivity of the light-absorbing layer instead of the light attenuation coefficient of the light-absorbing layer, and selecting a material which is prone to increased absorption of a laser beam at high temperatures during recording. A distinctive feature is that the absorbance or recording sensitivity of the dye material film used in the medium for recording optical information that has a writable structure is dependent on temperature. Specifically, it was found that the absorption spectrum of the dye material varies at high temperatures, and a relation A2/A1≧1.30 was established.

Abstract: An optical information medium is made up of a transparent substrate for a recording laser beam to penetrate therethrough, a recording layer formed on the transparent substrate, and a reflective layer for reflecting reproducing laser beam formed thereupon enabling the recording of optically readable signals by means of an incident recording laser from the transparent substrate. The transparent substrate has spiral-like tracking guides on the surface of the transparent substrate on which is formed the recording layer, and pre-pits indicative of address information are formed on a land portion defined between the tracking guides. The pre-pits are formed shifted from a center of the land. With this construction, the pre-pits open to a side of the tracking guide neighboring the land.

Abstract: An optical information medium is made up of a transparent substrate for a reproducing laser beam to penetrate therethrough, a recording layer formed on the transparent substrate and a reflective layer for reflecting the reproducing laser beam thereupon, thereby enabling the recording of optically readable signals by a recording laser beam incident upon the transparent substrate. This optical information medium has a spiral-like tracking guide on a side surface of the transparent substrate, on which the recording layer is formed, and on lands defined between the spiral-like tracking guide are formed land pre pits indicative of the sector information, including the address and so on, wherein the length of the land pre pits is selected to be from 50% to 83% of the length of the minimum pit and to be from 1.5 to 2.5 times the length of the channel clock.

Abstract: An optical information medium, comprising: a transparent substrate for penetrating a recording laser beam therethrough; a recording layer being formed on the transparent substrate; and a reflective layer being formed on the recording layer and for reflecting reproducing laser beam thereupon. A numerical aperture of an objective lens of an optical pickup for irradiating the recording laser beam on the recording layer is approximately 0.65, and the numerical aperture of an objective lens of the optical pickup for irradiating the recording laser beam on the reflection layer is approximately 0.60. An inclination angle &thgr; at both edgces of the groove for tracking, being formed spiral-like on the surface of the transparent substrate on which the recording layer is formed, with respect to the main surface of the transparent substrate is selected from 55° to 75°.

Abstract: An optical information medium, comprising: a transparent substrate for penetrating a recording laser beam therethrough; a recording layer being formed on the transparent substrate; and a reflective layer being formed on the recording layer and for reflecting reproducing laser beam thereupon. A numerical aperture of an objective lens of an optical pickup for irradiating the recording laser beam on the recording layer is approximately 0.65, and the numerical aperture of an objective lens of the optical pickup for irradiating the recording laser beam on the reflection layer is approximately 0.60. An inclination angle &thgr; at both edges of the groove for tracking, being formed spiral-like on the surface of the transparent substrate on which the recording layer is formed, with respect to the main surface of the transparent substrate is selected from 55° to 75°.

Abstract: An optical information medium comprises a pair of discs which are bonded to each other, an optical recording layer provided on at least one of the discs, and a reflecting layer formed on an upper side of the optical recording layer. The optical information medium further includes an adhesive for bonding the pair of discs provided on the reflecting layer, wherein the adhesive has a thickness ranging from 10 to 80 &mgr;m. A protecting layer is provided on the upper side of the reflecting layer wherein the pair of discs may be bonded by the protecting layer. The optical recording layer, reflecting layer and protecting layer may be directly sequentially provided on the disc but another substrate layer may be inserted between these layers. There is employed, as the adhesive, those including a reactive curing resin or a hot melt material, and it is preferable that the shrinkage rate of the adhesive be less than 15%.

Abstract: An optical information recording medium comprising a light transmitting substrate, a light absorptive layer containing at least one light absorbing substance formed on the substrate and a light reflective layer made of a metal film formed on the light absorptive layer, wherein an optical parameter represented by &rgr;=nabsdabs/&lgr; wherein nabs is the real part of the complex refractive index of the light absorptive layer, dabs is the average thickness of the light absorptive layer and &lgr; is the wavelength of a reading laser beam, is 0.6<&rgr;<1.6.

Abstract: An optical information recording medium having a recording layer comprising a dye layer containing a trimethine-based cyanine dye having nitro group attached to a benzene ring or to a naphthalene ring, both being bonded to indole ring, is capable of minimizing the second peak in relative to the main peak shown in FIG. 1, thus enabling the spectrum consisting of a main peak and a second peak to become sharp. The recording layer is capable of performing the recording and reading with a laser beam having a wavelength falling within a range of 620 nm to 690 nm.

Abstract: An optical data recording medium in which the shape of the dye spectrum of a dye film having a thin film thickness per unit absorbance is controlled so as to enable improvements in the recording speed during high speed recording, jitter, and modulation, wherein the optical data recording medium is characterized in that 0<D/C≦100, and 80≦D/B, where D (nm) is the mean film thickness of the light-absorbing layer, C (Abs) is the maximum absorbance (based on molecular absorption) of the light-absorbing substance, B (Abs) is the maximum absorbance (based on association absorption) of the light-absorbing substance, D/C is the unit absorbance thickness based on the molecular absorption, and D/B is the unit absorbance thickness based on the association absorption.

Abstract: An optical information recording medium comprising a substrate and an overlaying optical interference layer containing a trimethine dibenzoindolenine cyanine dye of a symmetric structure is capable of recording information with a laser beam having a wavelength of 640 nm or longer at a low recording power and the recorded information can be reproduced with the same laser.

Abstract: By keeping the imaginary number portion k of the complex index of refraction of the film of the light absorbing layer 3, the mean film thickness dav of the light absorbing layer 3, and the absorbency A related thereto within an appropriate range, the present invention provides an optical information recording medium with good recording sensitivity and playback properties, which makes possible high speed recording by increasing the sensitivity to the recording beam and stable recording with sufficient reflectivity, and which can reduce jitter. In the present invention, 0.13≦A≦0.21 where A (Abs) is the absorbency of the light absorbing layer at the wavelength of the recording beam; and 6.0≦k.dav≦12.0 where k is the imaginary number portion of the complex index of refraction of the film in the light absorbing layer and dav (nm) is the mean film thickness of the light absorbing layer, at the wavelength of the recording beam.

Abstract: An optical information recording medium comprising a light transmitting substrate, a light absorptive layer containing at least one light absorbing substance formed on the substrate and a light reflective layer made of a metal film formed on the light absorptive layer, wherein an optical parameter represented by .rho.=n.sub.abs d.sub.abs /.lambda. wherein n.sub.abs is the real part of the complex refractive index of the light absorptive layer, d.sub.abs is the average thickness of the light absorptive layer and .lambda. is the wavelength of a reading laser beam, is 0.6<.rho.<1.6.

Abstract: An optical information recording medium provided on a substrate with a recording layer including a dye layer; wherein the dye layer contains a cyanine dye; and the recording layer enables a recording and reproducing to be effected with a laser beam having a wavelength falling within a range of 620 nm to 690 nm; a refractive index "n" of the recording layer being in a range of 1.6 to 4.0 and an extinction coefficient "k" of the a recording layer being in a range of 0.01 to 0.45 when the laser beam having the wavelength is applied thereto; and the recording layer exhibiting a maximum absorption peak wavelength and a second largest absorption peak wavelength falling within a range of 500 nm to 655 nm as measured by means of a visible ultraviolet spectrometer. The dye may be a trimethine-base cyanine dye.

Abstract: An optical information medium comprises a first disc forming information recording layer on a main surface thereof, a second disc being bonded to the first disc at the surface where the information recording layer is formed by way of an adhesive. A hydrophilic resin film is formed on the surface of the disc at the inner peripheral side extending from the center hole to the information non-recording area. The hydrophilic resin film is damp and is rough compared with the other portion formed of non-hydrophilic resin, and it is elastic. The characters, patterns or designs can be printed on the optical information medium using water-base ink, etc. after manufacturing the optical information medium. Further, the hydrophilic resin film is formed on the disc at the portion outside the information recording area.

Abstract: An optical information recording substrate and method of producing the substrate, the substrate having a legible matter formed in a groove area thereof or a pit array area thereof, wherein the legible matter includes a plurality of grooves or pit arrays being partially different in the breadth or depth thereof. The grooves or arrays may be partially dislocated in the radial direction of the optical information recording substrate from a predetermined track. The visually legible matter may include a plurality of laser generated pit arrays wherein remaining portions of the legible matter have a plurality of continuous grooves formed therein. The legible matter may also include a plurality of continuous grooves wherein remaining portions of the legible matter includes a plurality of laser generated pit arrays formed therein.