Sanyo Electric Co., Ltd.

Michiyoshi Sawada

Akira Tsukihashi

Shigeru Nakamura

Mitsuhiro Hiruma

Misao Kuramochi

Hiromitsu Kondo

Kazunori Ueki

Tadashi Iwama

An optical disc apparatus comprising: an optical pickup unit having a semiconductor laser that radiates a laser light beam which is to be applied to an optical disc, a photo detector that has a plurality of light-receiving faces, which are disposed adjacent to each other, and each of which is disposed radially at an identical angle from a center of all of the plurality of light-receiving faces, and that, when the plurality of light-receiving faces receive a reflected light beam of the laser light beam applied to the optical disc, outputs photoelectric converted signals, each of which corresponds to a level of the reflected light beam at each of the plurality of light-receiving faces, a plurality of operational amplifiers that respectively output control signals for focus servo or track servo to the optical disc, based on the photoelectric converted signals, and an actuator that executes the focus servo or the track servo, based on the control signals; a driving unit that drives the actuator to execute the focus servo or the track servo, based on the control signals; a storage unit in which gain data is stored, the gain data being data for setting gains of the plurality of operational amplifiers; and a gain setting unit that adjusts gains of the plurality of operational amplifiers such that the gains have values equivalent to that the reflected light beam is evenly applied to the plurality of light-receiving faces, based on the gain data read from the storage unit.

Optical disc apparatus and optical pickup unit

In the optical pickup unit configured to guide a laser beam emitted from a laser source to an objective lens, to converge the laser beam with the objective lens to be irradiated to a disk, and to guide the laser beam reflected and returned by the disk to the photo detector including a light reception region constituted by a plurality of segments, the photo detector is disposed with each amplifier corresponding to each segment of the light reception region, is disposed with each output terminal that outputs each light reception output corresponding to each segment from the photo detector via each amplifier, and is disposed with an output setting circuit that sets each light reception output from each of the output terminals by changing the gain of each of the amplifiers and/or by attenuating the input or output of each of the amplifiers with an attenuator.

Light reception output controlling apparatus of photo detector in optical pickup unit

An optical system of an optical recording apparatus forms a main spot and sub-spots preceding and succeeding the main spot on a signal recording medium. The optical system is set such that the sub-spot is shifted from the main spot in the direction orthogonal to a signal track by a distance expressed by an expression (2k&#x2212;1)P/4(k=natural number), in which P denotes a distance between adjacent signal tracks on the signal recording medium. Thus, the sub-spot succeeding the main spot can be used to effectively read the state of a signal recorded on the signal recording medium by the main spot.

Optical recording apparatus and control method thereof

An optical system of an optical disk recording apparatus irradiates a disk with a main beam for use in writing a data signal onto a disk and a sub-beam succeeding the main beam. When writing a data signal onto the disk, a site on the disk at which a data signal is written by the main beam is subsequently irradiated with the succeeding sub-beam. Light of the succeeding sub-beam reflected from the disk is received by a succeeding light receiving sub-region. A sampling circuit samples a signal at periods when the emission power of the main beam is at the recording level, among output signals from the succeeding light receiving sub-region. Based on the sampled signal at the recording level, a &#x3b2; value detection circuit and a jitter amount detection circuit obtain a &#x3b2; value and a jitter amount indicative of the recording state of the data signal recorded on the disk, respectively.

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Gunma, Japan

Michiyoshi Sawada