EP0098076A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Beam access apparatus for optical disc system
Assignee: NEC Corp
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Filing: 1983-06-14
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Granted: —
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Expires: 2003-06-14
Abstract
Abstract A beam access apparatus for an-optical disc system includes an objective lens (55) whose position is detected in a tracking direction with respect to an optical base in an optical head (1). In a head access mode, the objective lens (55) is positioned and fixed at a prescribed position in the optical head (1) to suppress damping vibrations to enable the head to be accessed at a high speed. In a lens access mode and a track follow mode subsequent to the head access mode, the controlling position for the optical head (1) is such that the objective lens (55) is arranged at a prescribed position in the optical head (1) to enable a track to be followed precisely by a light spot and track jumping of the light spot to be reliably carried out by driving the objective lens.
Inventors
- 👤 Hiroshi c/o NEC Corporation Inada
- 👤 Tadashi c/o NEC Corporation Nomura
- 👤 Shigeru c/o NEC Corporation Shimonou
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-30 06:26
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/08; G11B7/09; G11B7/0901; G11B7/085; G11B7/08505; Y; Y10; Y10S; Y10S358/00; Y10S358/907
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
189 words
A beam access apparatus for an optical disc system for recording and reproducing information by means of a light beam emitted from a light source located on an optical base in an optical head and condensed into a minute light spot on a surface of a disc by an objective lens, comprising means for producing a lens position signal indicating a position of said objective lens in a radial direction of said disc with respect to said optical head, and means for moving said optical head and said objective lens, characterised in that said apparatus has a head access mode in which said optical head is moved in a radial direction and said objective lens is caused to follow the movement of said optical head such that said objective lens is located at a predetermined position with respect to said optical head, and a lens access mode in which said objective lens is moved in said radial direction and said optical head is caused to follow the movement of said objective lens such that said optical head is located at a predetermined position with respect to said objective lens.
Claim 2
Dependent Claim
189 words
A beam access apparatus for an optical disc system for recording and reproducing information by means of a light beam emitted from a light source located on an optical base in an optical head and condensed into a minute light spot on a surface of a disc by an objective lens, comprising means for producing a lens position signal indicating a position of said objective lens in a radial direction of said disc with respect to said optical head, and means for moving said optical head and said objective lens, characterised in that said apparatus has a head access mode in which said optical head is moved in a radial direction and said objective lens is caused to follow the movement of said optical head such that said objective lens is located at a predetermined position with respect to said optical head, and a lens access mode in which said objective lens is moved in said radial direction and said optical head is caused to follow the movement of said objective lens such that said optical head is located at a predetermined position with respect to said objective lens.
Claim 3
Dependent Claim
74 words
Apparatus as claimed in claim 1, characterised in that said moving means comprises a first feedback circuit for moving said optical head in said radial direction as a function of the difference between the present position of said optical head and a desired position of said optical head, and a second feedback circuit for moving said objective lens in a manner which maintains said objective lens and said optical head in said predetermined relationship.
Claim 4
Dependent Claim
97 words
Apparatus as claimed in claim 2, characterised in that said first feedback circuit comprises a head position detector for generating a head position signal indicative of the rate of movement of said optical head, a reference velocity generator for generating a reference velocity signal indicative of the desired velocity of said optical head, a head actuator for moving said optical head as a function of a head movement signal applied to said actuator, and means for generating said head movement signal as a function of said head position and reference velocity signals during the head access mode.
Claim 5
Dependent Claim
16 words
Apparatus as claimed in claim 3, characterised in that said generating means comprises a differential amplifier.
Claim 6
Dependent Claim
82 words
Apparatus as claimed in claim 3, characterised in that said first feedback circuit further comprises a counter which is loaded with a number indicative of the difference between the initial position of said optical head and the desired position of said optical head at the beginning of said head access mode and is thereafter decremented as a function of said head position signal, wherein said reference velocity generator generates said reference velocity signal as a function of the count in said counter.
Claim 7
Dependent Claim
60 words
An apparatus as claimed in claim 2, characterized in that said second feedback circuit comprises a lens actuator for positioning said objective lens in said optical head as a function of said lens position signal, and including means for applying said lens position signal to said lens actuator when said apparatus is operated in said head access mode of operation.
Claim 8
Dependent Claim
38 words
Apparatus as claimed in claim 1, characterised in that said moving means causes said objective lens to jump from one track to a successive track of said disc when said apparatus is operated in said lens access mode.
Claim 9
Dependent Claim
85 words
Apparatus as claimed in claim 7, characterised in that said moving means comprises a first feedback circuit for moving said objective lens from track to track in response to a track jump instruction applied thereto when said apparatus is operated in said lens access mode, and a second feedback circuit for moving said optical head in a manner which attempts to maintain said optical head at a first fixed position relative to said objective lens when said apparatus is operated in said lens access mode.
Claim 10
Dependent Claim
83 words
Apparatus as claimed in claim 8, characterised in that said first feedback circuit comprises a tracking position detector for generating a tracking position signal indicative of the position of said objective lens relative to said tracks, a lens actuator for adjusting the position of said objective lens as a function of a control signal applied thereto, and a lens access control circuit for generating said control signal as a function of said tracking position signal and in response to said track jump instruction.
Claim 11
Dependent Claim
31 words
Apparatus as claimed in claim 9, characterised in that said tracking position signal is an error signal indicative of the distance between said objective lens and a track of said disc.
Claim 12
Dependent Claim
71 words
Apparatus as claimed in claim 8, characterised in that said second feedback circuit comprises a head actuator which moves said optical head in response to said lens position signal in a manner which causes the position of said optical head relative to said objective lens to remain substantially constant, and means for applying said lens position signal to said head actuator when said apparatus is operated in said lens access mode.
References Cited (Backward Citations)
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