Tdk Corporation

Syuji Tsukamoto

Takashi Horai

Hiroyuki Arioka

Narutoshi Fukuzawa

Shirou Ootsuki

Motohiro Inoue

Hiroshi Take

A multi-level optical recording medium according to the present invention is a multi-level optical recording medium () which is capable of recording record data according to multi-level recording that defines light reflection ratios of recording portions () into multiple levels by switching the irradiation amount of a recording laser beam between multiple levels, wherein light reflection ratio information enabling identification of a light reflection ratio dynamic range within which respective light reflection ratios of the recording portions () should be included is readably recorded. Due to this construction, when record data are recorded, it is only required to record the record data such that the respective light reflection ratios of the recording portions () are included within the light reflection ratio dynamic range identified from the light reflection ratio information, and it is unnecessary to perform the operation of checking the characteristics of the multi-level optical recording medium () prior to recording the record data. Therefore, it is possible to record the record data promptly and easily without wastefully using a data-recording area.

Multi-level optical recording medium, multi-level recording method, and multi-level reproduction method

A method is provided for recording data in a write-once type optical recording medium which can record data by forming a recording mark having a desired length and reduce jitter of a reproduced signal. The method comprises determining a pulse train pattern so that a level of a pulse is switched from the level corresponding to the level of the recording power Pw to the level corresponding to the level of the bottom power Pb in accordance with the length of a blank region to be formed immediately after formation of a first recording mark and the length of a second recording mark formed subsequent to the formation of the first recording mark.

Method for recording data on optical recording medium, device for recording data on optical recording medium, and optical recording medium

A reproduction method for a multi-level optical recording medium according to the present invention rotates an optical recording medium, on which recording data has been recorded according to a multi-level recording method which sets several levels for light reflectivity of virtual recording cells, emits a reproduction laser beam towards the optical recording medium, and reproduces the recording data based on an electric signal generated in accordance with a received level of reflected light, the method setting the emission power of the reproduction laser beam in a range of 1.0 mW to 2.5 mW inclusive when the optical recording medium is rotated at a linear velocity in a range of 9 m/s to 25 m/s inclusive. By doing so, it is possible to improve the read accuracy for recording data while suppressing the reproduction deterioration of the optical recording medium to a level where deterioration effectively does not occur.

Multi-level optical recording medium reproducing method and reproducing device

On a recording layer () of a disc-shaped optical recording medium (), a plurality of virtual recording cells () are assumed contiguously in a spiral or concentric fashion in a groove (). The irradiation time of the laser beam is modulated in five stages or more for each of the virtual recording cells () in response to information to be recorded, thereby forming recording marks (A toG) of different sizes in five stages or more. The optical reflectivity of the virtual recording cell () is modulated in multi-stages to thereby vary the reflection level of a reading laser beam for reading operations in five stages or more. The length of the virtual recording cells () in the rotational direction of the disc is set to be equal to that of an arc having the same center angle with respect to the center of the disc.

Optical recording medium and optical recording method by irradiation

An optical multi-level recording medium, having a recording layer on which a recording mark is formed by irradiating a laser beam, plural virtual recording cells being continuosly formed in a relative moving direction to the laser beam on the recording layer with an arbitrary unit length and a unit width, five stages or more irradiation times being set so that the irradiation time becomes long successively from the first to final stages, a power average value of laser beam in a specific irradiation time of the plural-stage irradiation times being set so as to become larger than a power average value of another irradiation time longer than the specific irradiation time, and recording marks being formed in the virtual recording cell and giving five stages or more different optical reflectance when the laser beam is irradiated to the virtual recording cell.

Optical multi-level recording medium and optical multi-level recording method

An optical recording medium can be recorded at a high linear velocity of at least 10 m/s while maintaining an excellent light stability and favorable reflectance. A recording medium is constructed of a recording layer on a substrate, the recording layer including a first dye with a maximum absorption wavelength in a thin-film state of 450 nm to 620 nm inclusive as a first dye and being formed so as to include a second dye with an extinction coefficient of at least 0.5 for a recording wavelength. In this case, it is preferable for the second dye to have a maximum absorption wavelength of 620 nm to 750 nm inclusive in a thin-film state.

Optical recording medium

An optical recording method for irradiating an optical recording mediumwith a laser beam to form recording marksA toG. The method includes defining contiguously a virtual recording cellin a displacement direction S on the recording layer, setting reference irradiating time with the laser beam to five stages or more, and defining a predetermined waiting time in a neighboring subsequent virtual recording cell, corresponding to the length of the reference irradiating time in the preceding virtual recording cell. The method also includes setting actual irradiating time by subtracting the waiting time from the reference irradiating time for irradiation of the aforementioned subsequent virtual recording cellThe method further includes irradiating with the laser beam during the aforementioned actual irradiating time by delaying the irradiation initiation timing by the waiting time to form at least five types of recording marksA toG having different sizes, thereby performing multi-level recording of information.

Optical recording method, optical recording medium and optical irradiating time controlling device

An optical recording medium having a higher improved read accuracy is disclosed. In the case of irradiating a laser beam to an optical recording medium including an optical reflective layer and a recording layer so as to record information therein, in the recording layer, a virtual recording cell having an arbitrary unit length and a unit width perpendicular to the unit length is continuously defined. In the case where the laser beam is irradiated to the virtual recording cell over the entire allowable irradiation time T securable to one virtual recording cell, a reference power of the laser beam is preset so that an optical reflectance of the virtual recording cell can be reduced more than 50% with respect to the initial reflectance. Further, the laser beam having the preset reference power is irradiated to the virtual recording cell in a state that an irradiation time is modulated into five stages or more, and thereby, a recording mark giving five stages or more different optical reflectance to the virtual recording cell can be formed.

Optical recording medium with recording marks having different states, and method of recording using the optical recording medium

A laser beam is directed to an optical recording medium such as a DVD-R to successively form thereon marks of a length corresponding to data with a spacing disposed therebetween. A Q value or the amount of reduction in time causes the rise time of laser irradiation to be delayed with respect to the scheduled rise time at least after a spacing equal in length to the mark of the shortest length employed for recording. The Q value satisfies the following equation (1) expressed in terms of the relationship between the recording speed n and an asymmetry. That is,(0.54&#xd7;Asymmetry&#x2212;1.1)/(0.54&#xd7;Asymmetry&#x2212;0.1)/&#x2003;&#x2003;(1)where the asymmetry is the ratio of an amplitude of the shortest mark to that of the longest mark of the recorded marks.

Optical recording medium, optical recording device and optical recording method

An optical recording medium ( ) is adapted such that information is recorded by forming recording marks on a recording layer ( ) that covers grooves ( ) of an optical transparent substrate ( ). In the recording layer ( ), contiguously defined along a feed direction S of irradiation are virtual recording cells ( ) which have a given unit length in the feed direction S of irradiation along the groove and a given unit width in the direction orthogonal thereto. In addition, the groove width W is set so that 0.20&times;(&lgr;/NA)<W<0.50&times;(&lgr;/NA), where &lgr; is the wavelength of a laser beam to be irradiated with and NA is the numerical aperture of the objective lens for the laser beam in a irradiation optical system. The irradiation time is set in five stages or more to radiate the laser beam, thereby making it possible to record information in multi-levels.

Optical recording medium and optical recording method

An optical recording medium, which is suitable for multi-level recording forming a recording mark at multiple stages, is obtained. An optical recording medium, which is constructed in a manner that a recording mark is formed on the recording layer by irradiating a laser beam so as to record information, the recording layer being continuously formed in a relative moving direction to the laser beam with plural virtual recording cells, each of which has an arbitrary unit length and a unit width perpendicular to the unit length in the relative moving direction, plural-stage irradiation times being set with respect to the virtual recording cell so that the irradiation time becomes long successively from the first to final stages, a laser beam power being set in at least one irradiation time of the plural-stage irradiation times so as to intermittently become larger than a predetermined threshold value when the laser beam is irradiated to the virtual recording cell, and recording marks being formed in the virtual recording cell and giving plural-stages different optical reflectance to the virtual recording cell.

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Tokyo, Japan

Syuji Tsukamoto