EP0154302A2
Expired / Lapsed
EP
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Optical system for detecting a position of an objective lens
Assignee: Toshiba Corp
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Filing: 1985-02-28
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Granted: —
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Expires: 2005-02-28
Abstract
Abstract In an optical system, a laser beam emitted from a laser unit (2) is converted by a collimater lens (6) into a parallel light beam, and converged to a light reflecting surface (16) of an optical disk (14) having a tracking guide by an objective lens (12). The objective lens (12) is suspended in a lens barrel assembly (22) by a spring member so as to be moved by voice coil along the optical axis of the objective lens (12) for focus and by linear motor in a direction perpendicular to the optical axis for tracking control. As a result that the lens barrel assembly (22) is moved along the optical disk, the objective lens (12) is transferred to the direction perpendicular to the optical axis of the system. Then, part of the light beam transferred from the objective lens (12) is directed to any one of the first and second photosensitive sections (66-1, 66-2) of the photodetector (64). As a result that the linear motor is driven in response to the difference of the signals from the first and second photosensitive sections (66-1, 66-2), the vibration of the objective lens (12) can be stopped.
Inventors
- 👤 Hideo C/O Patent Division Ando
- 👤 Akihiko Doi
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 20:29
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/08; G11B7/09; G11B7/0946; G11B7/085; G11B7/08505
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
227 words
An optical system having a fixed optical axis, for focusing a light beam onto a light reflecting surface (16) comprising: a light source (2) for generating a light beam, means (6) for collimating a light beam, an objective lens (12) having an optical axis, for converting the collimated light beam on the light reflecting surface (16) and transferring the light beam reflected from the light reflective surface (16), means (28, 30, 40) for supporting said objective lens (12) movably to the optical axis of the lens (12) and to the direction perpendicular thereto, and means (32, 34, 42, 44) for finely moving said objective lens (12) to the optical axis of said objective lens (12) and to the direction perpendicular to the optical axis in the collimated light beam, means (22) for moving a head assembly (22) including said objective lens, said means for supporting said objective lens and said means for finely moving said objective lens along the light reflecting surface in a predetermined direction, characterized by further comprising photodetecting means (64) having at least first and second photosensitive sections (66-1, 66-2) for detecting a light beam to direct part of the light beam transferred from said objective lens (12) toward any one of the first and second photosensitive sections (66-1, 66-2) when transferring said objective lens (12) to the direction perpendicular to the optical axis.
Claim 2
Dependent Claim
227 words
An optical system having a fixed optical axis, for focusing a light beam onto a light reflecting surface (16) comprising: a light source (2) for generating a light beam, means (6) for collimating a light beam, an objective lens (12) having an optical axis, for converting the collimated light beam on the light reflecting surface (16) and transferring the light beam reflected from the light reflective surface (16), means (28, 30, 40) for supporting said objective lens (12) movably to the optical axis of the lens (12) and to the direction perpendicular thereto, and means (32, 34, 42, 44) for finely moving said objective lens (12) to the optical axis of said objective lens (12) and to the direction perpendicular to the optical axis in the collimated light beam, means (22) for moving a head assembly (22) including said objective lens, said means for supporting said objective lens and said means for finely moving said objective lens along the light reflecting surface in a predetermined direction, characterized by further comprising photodetecting means (64) having at least first and second photosensitive sections (66-1, 66-2) for detecting a light beam to direct part of the light beam transferred from said objective lens (12) toward any one of the first and second photosensitive sections (66-1, 66-2) when transferring said objective lens (12) to the direction perpendicular to the optical axis.
Claim 3
Dependent Claim
54 words
An optical system according to claim 1, characterized in that first and second photosensitive sections (66-1, 66-2) are arranged out of an optical path, through which a light beam transferred from said objective lens (12) is passed when the optical axis of said objective lens (12) is aligned with that of said optical system.
Claim 4
Dependent Claim
26 words
An optical system according to claim 1, characterized by further comprising: a projection lens (50) for converting a light beam transferred from said objective lens (12).
Claim 5
Dependent Claim
54 words
An optical system according to claim 3, characterized in that first and second photosensitive sections (66-1, 66-2) are arranged out of an optical path, through which a light beam converted by the projection lens (50) is passed when the optical axis of said objective lens (12) is aligned with that of said optical system.
Claim 6
Dependent Claim
41 words
An optical system according to claim 1, characterized in that said means (32, 34, 42, 44) for finely moving said objective lens is energized in response to the difference of signals generated from the first and second photosensitive sections (66-1, 66-2).
Claim 7
Dependent Claim
57 words
An optical system according to claim 1, characterized in that said means (32, 34, 42, 44) for finely moving said objective lens (12) stops the movement of the objective lens (12) in response to the difference of signals generated from the first and second photosensitive sections (66-1, 66-2), when the head assembly (22) is caused to move.
Claim 8
Dependent Claim
57 words
An optical system according to claim 1, characterized by further comprising: a tracking guide formed on said light reflecting surface (16), and means (64-1, 64-2) for detecting a light beam transferred from the objective lens (12) to generate a tracking signal, thereby energizing said means for finely moving the objective lens in response to the tracking signal.
Claim 9
Dependent Claim
109 words
An optical system according to claim 1, characterized by further comprising: means (80, 74) for connecting said photodetecting means (66-1, 66-2) to said means (32, 34, 42, 44) for finely moving the objective lens (12) and disconnecting said means (64-1, 64-2) for generating a tracking signal when said head assembly (22) is moved, and disconnecting said photodetecting means (66-1, 66-2) from said means (32, 34, 42, 44) for finely moving the objective lens (12) and connecting said means (64-1, 64-2) for generating a tracking signal when the head assembly (2) is stopped and the optical axis of the objective lens (12) is aligned with that of said optical system.
References Cited (Backward Citations)
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