Sanyo Electric Co., Ltd.

Yasuhiro Muraoka

Hiroshi Yoshida

Yoshimaru Nakane

Tatsushi Arai

Masaharu Sakazume

Shinya Tsukada

A disc apparatus is disclosed that includes a jitter-value detection unit configured to detect a jitter value based on a signal to be read from a medium. A detrack-value setting unit is configured to set a detrack value for focusing an objective lens in the medium based on the jitter value. A detrack-value adjusting unit is configured to detect the jitter value every time the detrack value is changed stepwise within a predetermined range of the detrack value including a reference value of the detrack value, to obtain an optimum detrack value to be set in the detrack-value setting unit, based on a maximum jitter value and a minimum jitter value of the detected jitter values.

Disc apparatus

An inspecting method for an object lens driving device including a base, an objective lens, a holder for holding the objective lens on the base, and a drive mechanism for driving the holder so as to move the objective lens in the focus direction, the method comprising the steps of: emitting a laser beam through the objective lens; allowing the laser beam emitted through the objective lens to pass through an aperture having a predetermined diameter; applying to the drive mechanism a drive voltage for moving the holder between a first position closest to a surface of the base and a second position farther than the first position from the surface of the base; performing photoelectric conversion of the laser beam having passed through the aperture; and inspecting the objective lens driving device based on a signal obtained by the photoelectric conversion.

Use of a photoelectric converted signal to inspect an objective lens driving device

A disc apparatus comprising: a jitter-value detection unit configured to detect a jitter value based on a signal to be read from a medium; a defocus-value setting unit configured to set a defocus value for focusing an objective lens in the medium based on the jitter value; and a defocus-value adjusting unit configured to detect the jitter value every time the defocus value is changed stepwise within a predetermined range of the defocus value including a reference value of the defocus value, to obtain an optimum defocus value to be set for the defocus-value setting unit within a predetermined time period, based on a maximum jitter value and a minimum jitter value of the detected jitter values.

An optical disc apparatus is disclosed that comprises a jitter value detecting circuit that detects a jitter value based on the signal read out from an optical disc; and a defocus value setting circuit that adjusts a defocus value used for moving an objective lens along the direction of a light axis when focusing of the objective lens to the optical disc is performed, based on the signal that has gone through the jitter value detecting circuit, and causes a defocus adjustment to be made based on the defocus value.

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Gunma, Japan

Yasuhiro Muraoka