Abstract: An erasable phase change recording medium includes a transparent substrate, a recording layer of a phase change material provided on the substrate, and a protection layer provided to protect the recording layer on the substrate. Tracks are formed with alternate grooves and lands on the substrate of the recording medium and data is recorded to at least one of the grooves and the lands. The recording medium is configured to have a track pitch between 0.6 .mu.m and 0.8 .mu.m and a groove depth between 0.11.L and 0.18.L where L is a wavelength of a laser beam.

Abstract: An irradiation method of applying a light spot or a light pattern to an object with high resolution is performed by disposing, in close vicinity to the object, a light-absorbing contrast-increasing layer whose transmittance or reflectivity with respect to an incident light thereto increases as the intensity of the incident light or the exposure thereof to the incident light increases; and applying light to the object through the light-absorbing contrast-increasing layer. This method is applied to an optical information recording and reproducing method using an optical information recording medium including an optical information recording layer and an auxiliary layer whose transmittance or reflectance increases in a real time manner correspondingly to the energy of an incident light thereto.

Abstract: An optical data recording/reproducing method in which data is recorded for testing in a pattern including a not-recorded section and a recorded section as changing a recording power P onto an optical data recording medium from time to time, An amplitude m of the recorded data corresponding to the recording power P is monitored by reproducing the data recorded for testing. A standardized gradient g(P) is calculated from the following expression:g(P)=(.DELTA.m/m)/(.DELTA.P/P)or h(P) is calculated from the following expression:h(P)=(.DELTA.m/m)/.DELTA.Pwherein .DELTA.P indicates a minute change rate near P and .DELTA.m indicates a minute change rate corresponding to .DELTA.P near m, and an optimum recording power is decided and set by evaluating whether the recording power is too high or too low according to the standardized gradient g(P) or h(P).

Abstract: A method of recording a bit stream on a Phase Change media by illuminating a laser beam on the Phase Change media includes assigning a predetermined number of channel bits to each bit of the bit stream, and assigning one of a highest power level, an intermediate power level, and a lowest power level of the laser beam to each of the channel bits so as to modulate the laser beam, wherein an arrangement of the highest power level, the intermediate power level, and the lowest power level for one bit of the bit stream depends on values of the one bit and an immediately preceding bit.

Abstract: When recording data according to the PWM recording system by modulating signals, pulse modulation for pulse modulation for recording for recording a 0 signal or the like having a signal width of nT (T: Clock time) after modulation is a continuous electro-magnetic wave at a power level e, a record signal pulse array for recording a 1 signal or the like having a signal width of nT after modulation comprises a pulse section fp having a time width x and a power level a, a multi-pulse section mp in which a low level pulse at a power level b and a high power pulse at a power level c having a time width T in total alternately appear (n-n') times in all with a duty ratio y, and a pulse section op having a time width z and a power level d, and x, y, z are integers satisfying the conditions of 0.5 T.ltoreq.x.ltoreq.2 T, 0.4.ltoreq.y.ltoreq.0.6 and 0.5 T.ltoreq.z.ltoreq.

Abstract: An optical recording medium composed of a transparent substrate, with an organic dye-containing layer and a light reflection layer formed on the substrate in that order, which recording medium performs recording and reproducing operations by the application of light beams used for the recording and reproducing operations respectively to the side of the transparent substrate, the organic dye-containing layer showing a light absorption ratio of 20% or more with respect to a light beam with a wavelength of 500 to 750 nm used in a recording operation, and showing a light absorption ratio of 20% or less with respect to a light beam with a wavelength of 760 to 830 nm used in a reproducing operation. In addition, the method of recording and reproducing information using the above-mentioned optical recording medium.

Abstract: When recording data according to the PWM recording system by modulating signals, pulse modulation for pulse modulation for recording for recording a 0 signal or the like having a signal width of nT (T: Clock time) after modulation is a continuous electro-magnetic wave at a power level e, a record signal pulse array for recording a 1 signal or the like having a signal width of nT after modulation comprises a pulse section fp having a time width x and a power level a, a multi-pulse section mp in which a low level pulse at a power level b and a high power pulse at a power level c having a time width T in total alternately appear (n-n') times in all with a duty ratio y, and a pulse section op having a time width z and a power level d, and x, y, z are integers satisfying the conditions of 0.5T .ltoreq.x.ltoreq.2T, 0.4.ltoreq.y.ltoreq.0.6 and 0.5T.ltoreq.z.ltoreq.

Abstract: An irradiation method of applying a light spot or a light pattern to an object with high resolution is performed by disposing, in close vicinity to the object, a light-absorbing contrast-increasing layer whose transmittance or reflectivity with respect to an incident light thereto increases as the intensity of the incident light or the exposure thereof to the incident light increases; and applying light to the object through the light-absorbing contrast-increasing layer. This method is applied to an optical information recording and reproducing method using an optical information recording medium including an optical information recording layer and an auxiliary layer whose transmittance or reflectance increases in a real time manner correspondingly to the energy of an incident light thereto.

Abstract: An irradiation method of applying a light spot or a light pattern to an object with high resolution is performed by disposing, in close vicinity to the object, a light-absorbing contrast-increasing layer whose transmittance or reflectivity with respect to an incident light thereto increases as the intensity of the incident light or the exposure thereof to the incident light increases; and applying light to the object through the light-absorbing contrast-increasing layer. This method is applied to an optical information recording and reproducing method using an optical information recording medium including an optical information recording layer and an auxiliary layer whose transmittance or reflectance increases in a real time manner correspondingly to the energy of an incident light thereto.

Abstract: The present invention relates to a method of recording and reproducing data on a recording medium, wherein original data is recorded on a recording medium by converting it into a code having more than one "0" between bits "1" such as MFM code and RLL (1,7) code, and a timing of a zero-cross of a reproductive signal or a second order differential signal from the recording medium is detected to obtain a bit "1" and reproduce the original data. The method allows to avoid affect of interference between marks and to record and reproduce data at high recording density and with high reliability.

Abstract: A method for recording or reproducing information on or from a recording medium, the method capable of reproducing serial data on the basis of signals derived on each of front edges or each of rear edges of a plurality of pieces of recorded information on the recording medium, includes the steps of reproducing bit-synchronization signals corresponding to each ones of the front and rear edges from signals derived on the front and rear edges alternately provided in the recorded information, the bit-synchronization signals having individual phases but the same frequency as each other, switching the bit-synchronization signal for each of the front edges into the other bit-synchronization signal for each of the rear edges or vice versa after a predetermined time each time the bit-synchronization signal is detected, synthesizing the bit-synchronization signals so that a phase of the synthesized bit-synchronization signal constantly matches to phases of the front and rear edges to be detected, and sequentially repro

Abstract: An optical information recording method for recording one of signals "1" and "0" in each of bit positions alloted at regular intervals along a track of a recording medium. The method comprises the step of enhancing energy for recording a bit of "1" which is directly subsequent to a bit of "0" in comparison to energy for recording a bit of "1" which is directly subsequent to a bit of "1".

Abstract: A method of reproducing optical information by utilizing an optical information recording medium is disclosed, in which a timing mark is formed on each information track in the recording medium; an information mark is formed on each information track with a predetermined cycle at a predetermined distance from the timing mark, which is a starting point of the information mark; comprising the steps of (a) scanning the information track at a specified scanning speed using a light spot; (b) detecting physical changes caused by the timing marks and information marks in the light reflected or transmitted from the optical information recording medium; and (c) reproducing the optical information by determining the presence or absence of an information mark by performing particular calculations as described in the specification.

Abstract: An optical information recording medium is composed of a substrate and a recording layer which includes a diarylpolyene compound of formula (I): ##STR1## wherein A.sup.1 and A.sup.2 each independently represent an aryl group which may have a substituent; R.sup.1 and R.sup.2 each represent hydrogen, a halogen or an alkyl group having 1 to 4 carbon atoms; and n is an integer of 2 or more.

Abstract: An optical information storage medium is used for recording optical information therein and reproducing optical information therefrom. The optical information storage medium includes parallel, concentric, or helical tracking guide grooves and information tracks defined between the tracking guide grooves. A preformat area composed of discrete pits is disposed on some of the information tracks. The tracking guide grooves and the preformat pits are defined in one surface of a transparent substrate, and a recording film capable of absorbing and reflecting light is disposed on said one surface of the transparent substrate. The ratio of the effective depth of the tracking guide grooves to the wavelength of a recording/reproducing laser beam within the transparent substrate is in a certain range, and the ratio of the effective depth of the preformat pits to the wavelength of the recording/reproducing laser beam within the transparent substrate is also in a certain range.

Abstract: This invention relate to an optical information recording medium, characterized by having an organic thin film recording layer containing at least one of compounds expressed by the general formula (I), (II), (III) and (IV): ##STR1## (wherein in the above formulas, A, B, D and E represent a substituted or non-substituted aryl group; R.sub.1 to R.sub.8 may be the same or different and represent hydrogen atom, halogen atom or alkyl group; Y represents a divalent residue having atomic groups necessary for forming a five-membered ring or six-membered ring; m, n and l represents 0, 1 or 2; ans X.sup.

Abstract: An information signal reconstructing method and apparatus for use in an optical disk system is provided. Data stored on an optical disk in a binary format is optically scanned by a photodetector to provide a detection signal. The average of this detection signal is first determined and then, using the thus determined average, the detection signal is subjected to an amplitude limiting operation so that there is obtained an output signal as an information signal reflecting the binary information of the data stored on the optical disk. During the amplitude limiting operation, the signal is so processed to have the same positive and negative amplitudes with respect to the average which is set at a zero level.

Abstract: This invention provides an optical information recording medium that has, on a substrate, a recording layer containing a cyanine dye represented by the general formula: ##STR1## (wherein, R.sub.1, R.sub.2 and R.sub.3 may be the same or different and each stands for a substituted or unsubstituted alkyl group; X stands for a perhalogenate ion, a toluenesulfonate ion or an alkylsulfate ion; n stands for an integrer of 0 or 1-3; a first halogen atom is present in at least one of each 4, 6 and 7-positions of the indole and indolenine rings; a second halogen atom may be present in each 5-position of said rings; and at lest one group consisting of alkyl, alkoxy, hydroxy, carboxy, allyl and alkylcarbonyl may be present in at least one of each 4, 5, 6 and 7-positions of said rings.) and, if necessary, a transition metal complex or a salt of said complex with a cation.

Abstract: This invention relates to an optical information recording medium, characterized by having an organic thin film recording layer containing at least one of triaryl methane type coloring matters expressed by the general formula (1), (2) or (3): ##STR1## (wherein, in the above formulas (1) and (2), Ar.sub.1, Ar.sub.2 and Ar.sub.3 may be the same or different and represent a substituted or non-substituted arylene group, at least one pair of optical two nitrogen atoms bonded with said arylene groups being connected by an atomic chain having at least ten carbon atoms in total number in the shortest way; R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, R.sub.6 and R.sub.

Abstract: The present invention relates to an optical information recording medium comprising a recording layer applied directly on a substrate or applied on a substrate by intervening an underlayer therebetween, and further comprising a protective layer on said recording layer if necessary, characterized in that said recording layer contains at least one of the compounds expressed by the following general formula (I) or (II): ##STR1## (wherein in the above formulas, X.sub.1 to X.sub.3 represent O, S or Se; A.sup.- represents an anion; l, m or n represents 0 or 1; R.sub.4 represents a substituted or non-substituted aryl group or heterocyclic group; R.sub.3, R.sub.5, R.sub.6, R.sub.9, R.sub.10 and R.sub.11 represent hydrogen or an alkyl group; R.sub.1, R.sub.2, R.sub.7, R.sub.8, R.sub.12, and R.sub.13 represent hydrogen or a substituted or non-substituted alkyl, aryl or styryl group; Z.sub.1, Z.sub.3 and Z.sub.