US 5,434,834 AGranted

Optical recording and reproducing apparatus for tracking wobbling guide grooves

AssigneeMitsubishi Denki Kabushiki Kaisha

InventorsMasahisa Shinoda, Kenjiro Kime, Toshiya Matozaki, Keiji Nakamura, Toru Yoshihara, Takeshi Ito

Life of this patent

Estimating the term…

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Abstract

An optical recording and reproducing apparatus uses a laser to form one or more spots on an information recording medium preformatted with wobbling guide grooves, and detects tracking error. If the differential push-pull method of detecting tracking error is used, a center spot is flanked by satellite spots distant by an odd multiple of half the repeating period of tile wobble. If the three-beam method is used, the distance is an odd multiple of one-fourth the repeating period of the wobble. If the push-pull method is used, a split photodetector generates a pair of electrical signals. The sum and difference of these signals are filtered, then synchronously detected, and the result is combined with the difference signal to generate a corrected tracking error signal.

Claims7

Dependent claims

An optical apparatus for recording and reproducing information on or from an information recording medium having tracks that wobble with a certain repeating period, said apparatus comprising:

a laser for emitting a laser beam;
an optical system for receiving said laser beam and forming a spot on said information recording medium;
a split photodetector for receiving reflected light from said spot and generating a pair of electrical signals;
a differential amplifier coupled to receive said pair of electrical signals and generate a difference signal;
a summing amplifier coupled to receive said pair of electrical signals and generate a sum signal;
a filter coupled to receive said difference signal and extract a wobble component thereof;
a synchronous detector coupled to receive and synchronously detect said sum signal and said wobble component, thereby generating a correction signal;
and
a correction circuit coupled to receive and combine said difference signal and said correction signal, thereby generating a tracking error signal.

6 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/321,876Filed 14 Oct 1994 · division
Priority: JP 3-21702728 Aug 1991
Granted: 18 Jul 1995
Term ends: Not estimatedThe source records don’t support an estimate.

Classification4 codes

G11B 7/0938
With provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record…
G11B 7/0904
For track following only: dithered tracking systems
G11B 7/094
With provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record…
G11B
Information storage based on relative movement between record carrier and transducer

Family

Serial935,925Parent of this division · filed 27 Aug 1992
Serial196,463Parent of this division · filed 15 Feb 1994
US 5,383,169 AParent of this division
US 5,303,216 AParent of this division
US 5,434,834 AThis patent

From the US filing history. Foreign family members aren’t listed.