Patent EP0530023A2 successfully refreshed from Google Patents.
EP0530023A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Optical recording and reproducing apparatus for tracking wobbling guide grooves
Assignee: Mitsubishi Electric Corp
•
Filing: 1992-08-27
•
Granted: —
•
Expires: 2012-08-27
Abstract
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 the 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.
Inventors
- 👤 Masahisa c/o Mitsubishi Denki K.K. Shinoda
- 👤 Kenjiro C/O Mitsubishi Denki K.K. Kime
- 👤 Toshiya c/o Mitsubishi Denki K.K. Matozaki
- 👤 Keiji c/o Mitsubishi Denki K.K. Nakamura
- 👤 Toru c/o Mitsubishi Denki K.K. Yoshihara
- 👤 Takeshi c/o Mitsubishi Denki K.K. Ito
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 06:53
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/08; G11B7/09; G11B7/0938; G11B7/0901; G11B7/0904; G11B7/094
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
260 words
An optical apparatus for recording and reproducing information on or from an information recording medium having guide grooves that are disposed at a certain pitch and that wobble with a certain repeating period, said apparatus comprising: a laser for emitting at least one laser beam; an optical system for receiving said laser beam and forming a center spot and two satellite spots on said information recording medium, said center spot and said two satellite spots being aligned in a straight line at an angle to said guide grooves with said center spot disposed midway between said two satellite spots and distant from each of said two satellite spots by an odd multiple of substantially one-half said repeating period in a longitudinal direction of said guide grooves; a first split photodetector for receiving reflected light from said center spot and generating a first pair of electrical signals; a second split photodetector for receiving reflected light from one of said two satellite spots and generating a second pair of electrical signals; a third split photodetector for receiving reflected light from another of said two satellite spots and generating a third pair of electrical signals; and a tracking error detection circuit for generating a first difference signal from said first pair of electrical signals, a second difference signal from said second pair of electrical signals, and a third difference signal from said third pair of electrical signals, then adding said second difference signal and said third difference signal and subtracting their sum from said first difference signal to generate a tracking error signal.
Claim 2
Dependent Claim
33 words
The apparatus of claim 1, wherein said center spot is distant from each of said two satellite spots by substantially half said pitch of said grooves in a lateral direction of the grooves.
Claim 3
Dependent Claim
189 words
An optical apparatus for recording and reproducing information on or from an information recording medium having tracks that are disposed at a certain pitch and that wobble with a certain repeating period, said apparatus comprising: a laser for emitting at least one laser beam; an optical system for receiving said laser beam and forming a center spot and two satellite spots on said information recording mediunn, said center spot and said two satellite spots being aligned in a straight line at an angle to said tracks with said center spot midway between said two satellite spots, said center spot being distant from each of said two satellite spots by an odd multiple of substantially one-fourth said repeating period in a longitudinal direction of said grooves; a first photodetector for receiving reflected light from one of said two satellite sports and generating a first electrical signal; a second photodetector for receiving reflected light from another of said two satellite spots and generating a second electrical signal; and a tracking error detection circuit for subtracting said second electrical signal from from said first electrical signal to generate a tracking error signal.
Claim 4
Dependent Claim
33 words
The apparatus of claim 3, wherein said center spot is distant from each of said two satellite spots by substantially one-fourth said pitch of said grooves in a lateral direction of the grooves.
Claim 5
Dependent Claim
34 words
The apparatus of claim 1, 2, 3 or 4, wherein said laser emits a single laser beam and said optical system has a diffraction grating for separating said single laser beam into three beams.
Claim 6
Dependent Claim
28 words
The apparatus of claim 1, 2, 3 or 4 wherein said laser is a monolithic semiconductor laser array that emits three laser beams from a single lasing region.
Claim 7
Dependent Claim
30 words
The apparatus of claim 1, 2, 3 or 4 wherein said laser is a hybrid semiconductor laser array having three lasing regions, each of which emits a single laser beam.
Claim 8
Independent Claim
40 words
The apparatus of any one of claims 1 to 7, wherein said information recording medium rotates with a constant linear velocity between 1.2 and 1.4 meters per second, and said tracks wobble at a frequency of 22.05 ± 1 kilohertz.
Claim 9
Dependent Claim
31 words
The apparatus of claim 8, wherein said center spot is separated from each of said satellite spots by a distance not less than 24 microns and not greater than 35 microns.
Claim 10
Dependent Claim
31 words
The apparatus of claim 8, wherein said center spot is separated from each of said satellite spots by a distance not less than 11 microns and not greater than 18 microns.
Claim 11
Dependent Claim
31 words
The apparatus of claim 8, wherein said center spot is separated from each of said satellite spots by a distance not less than 33 microns and not greater than 54 microns.
Claim 12
Dependent Claim
157 words
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.
Claim 13
Dependent Claim
12 words
The apparatus of claim 12, wherein said filter is a bandpass filter.
Claim 14
Dependent Claim
20 words
The apparatus of claim 12 or 13, wherein said synchronous detector comprises a low-pass filter for filtering said sum signal.
Claim 15
Dependent Claim
20 words
The apparatus of claim 12 or 13, wherein said synchronous detector comprises a bandpass filter for filtering said sun signal.
Claim 16
Dependent Claim
14 words
The apparatus of claim 12 or 13, wherein said synchronous detector comprises a multiplier.
Claim 17
Dependent Claim
25 words
The apparatus of claim 12 or 13, wherein said synchronous detector comprises a low-pass filter for reflecting a wobble frequency component of said correction signal.
Claim 18
Independent Claim
42 words
The apparatus of any one of claims 12 to 17, wherein said correction circuit comprises an amplifier for amplifying said correction signal to generate an amplified correction signal, and a differential amplifier for subtracting said amplified correction signal from said difference signal.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.