Sony Corporation

Toshiki Udagawa

Shunji Yoshimura

Atsushi Fukumoto

Masumi Ono

Kouichi Yasuda

Masumi Ohta

Isamu Nakao

Kiyoshi Ohsato

Hitoshi Okada

Atsushi Fukimoto

Taro Nishiura

[Object] To provide a technology capable of appropriately determining whether overcurrent has flowed in a light emitting element even in a case where the light emitting element is driven by the pulse driving method. [Solving Means] An overcurrent determination circuit according to the present technology includes: a sample-and-hold circuit that obtains a driving current value of a light emitting element in accordance with a timing of a light emitting interval of the light emitting element that emits pulsed light; and a comparator circuit that compares the obtained driving current value with a value of a predetermined determination level and determines whether overcurrent has flowed in the light emitting element.

Overcurrent determination circuit and light emission control apparatus

An optical recording apparatus which obtains the most appropriate recording laser power state in real time according to an environmental mark-generation condition. When data is recorded (marks and spaces are generated) by emitting pulse-train-manner laser outputs to an organic-pigment recording medium, a space-period signal value corresponding to a space period is detected in a reflected-light information signal to estimate a first-pulse signal value corresponding to a first pulse. In addition, a second-and-subsequent-pulse signal value corresponding to second and subsequent pulses is detected in the reflected-light information signal. The ratio between the estimated first-pulse signal value and the detected second-and-subsequent-pulse signal value is obtained, and the obtained ratio and a reference ratio are used to generate a laser-power compensation signal to control the power of the laser outputs.

Optical recorder and laser power control method

An optical recording apparatus obtains the most appropriate recording laser power state in real time according to an environmental mark-generation condition. When data is recorded (mark is generated) by emitting pulse-train-manner laser outputs to an organic-pigment recording medium, a first signal value corresponding to a first pulse in the pulse-train-manner laser outputs and a second signal value corresponding to second and subsequent pulses in the pulse-train-manner laser outputs are detected as a reflected-light information signal; the ratio thereof is obtained; and the obtained ratio and a reference ratio are used to generate a laser-power compensation signal to control the power of the laser outputs.

An apparatus for recording and/or reproducing a magneto-optical recording medium having a recording layer, a reproducing layer and an intermediate layer for magnetically coupling the recording layer and the reproducing layer in a stationary state, in which the magnetic coupling between the recording layer and the reproducing layer is only able to take place in an area in which a temperature is increased to be higher than a predetermined temperature by the radiation of a light upon reproducing and in which a recorded information held in the recording layer is read out from the reproducing layer in the radiated area. This magneto-optical recording medium is characterized in that a Curie temperature of the intermediate layer is selected to be 150.degree. C. or more. Also, an apparatus which performs the above-mentioned functions and additionally which is capable of recording and/or reproducing conventional magneto-optical discs which reproduce and/or record over the entire area of irradiation.

Magneto-optical medium and recording and/or reproducing apparatus thereof

An optical recording apparatus for recording a pulse signal on a recording medium by using a laser light beam, wherein, as shown in FIG. 4 , for example, a pattern detecting circuit (31) is provided to detect a pulse pattern of a recording signal, and an amplitude of a succeeding signal pulse is decreased in accordance with a control signal from a memory (33) when a pulse interval is not more than a predetermined value to thereby decrease a radiation energy of a laser light pulse, whereby the influence of remaining heat of the recording medium due to a laser light pulse corresponding to a preceding laser light pulse is cancelled to make it possible to record a high-density pulse signal accurately.

Optical recording apparatus

Optical recording medium

Method for reproducing signals recorded on optical recording medium

Disclosed is a method for recording and reproducing sector control information to and from a novel magneto-optical disk to which the so-called erasure type data reproduction method or data-embossed type reproduction method applies. On the magneto-optical disk, sector control information is recorded onto a sector control information recording region at a track recording density lower than that of a data recording region. When data is recorded on the disk at a high track density, the sector control information is recorded in such a manner that the information will not exist on adjacent tracks along the same radials of the disk.

Method for recording sector control information on magneto-optical disk

This invention is directed to an improvement in a novel magneto-optical disc reproducing method of the record information erasing type or the record information raised or transfer type wherein a technique is employed to prevent the dimension of an actual reproduction region from varying by a change of temperature or linear velocity of a magneto-optical disc. To realize this, reference information is recorded on a magneto-optical disc to reproduce this reference information prior to actual data reproduction to detect the regenerative RF signal level to control a laser power or an external magnetic field so that the regenerative RF signal level becomes equal to a level optimum for reproduction, thus allowing the dimension of an actual reproduction region to be an optimum fixed dimension at all times. At the time of actual reproduction, control is made so that the controlled laser power or external magnetic field is maintained.

Method for reproducing information recorded on a magneto-optical

Positional detection of a magneto-optic recording medium for controlling

Temperature detection of a magneto-optic recording medium for

A method and apparatus for recording and reproducing information onto and from a magneto-optic recording medium is disclosed. The magneto-optic recording medium has at least a reproducing layer and a recording layer. A recording optical head records information on the magneto-optic recording medium. A reproducing optical head has a reading light beam for reading information recorded in a region within a spot of the reading light beam by magneto-optic effect by changing a state of magnetization of the reproducing layer and at the same time irradiating the recording medium with the light beam. A wavelength of the recording light beam emitted by the recording optical head is substantially smaller than a wavelength of the reading light beam emitted by the reading optical head. A minimum ratio of the wavelength of the recording light beam to that of the reproducing light beam is 1:3.

Magneto-optic recording method and magneto-optic recording/reproducing

An optical recording and/or reproducing apparatus comprising a light beam generator, a photodetector, an optical path forming device for causing a light beam from the light beam generator to impinge upon an optical disc and for guiding the light beam emanating from the optical disc to the photodector, and a signal generating circuit block operative to obtain based on a detection output obtained from the photodetector a first signal representing a tracking condition of the light beam in relation to a record track portion on the optical disc and a second signal different in phase by substantially ninety degrees from the first signal and to produce a tracking error signal which satisfies the following equation:

Growing community of inventors

Tokyo, Japan

Toshiki Udagawa