EP0084703A2
Expired / Lapsed
EP
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Partial beam focus sensing device
Assignee: Control Data Corp
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Filing: 1982-11-11
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Granted: —
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Expires: 2002-11-11
Abstract
Abstract A partial beam focus sensing device comprises a lens element (20; 30; 40; 70) receiving a collimated light beam (12) reflected from optical recording media, and a light detector array (26; 46; 76). A centrally symmetric mask element (16; 100) adjacent to the lens element illiminates a portion of the light beam and transmits a partial light beam. The light detector array comprises at least two light detector elements (26a, 26b; 46a, 46b) mathced to the mask element and disposed to receive the partial beam from the lens element.
Inventors
- 👤 Curtis Alan Shuman
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-26 20:30
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/12; G11B7/135; G11B7/1381; G02; G02B; G02B27/00; G02B27/40; G11B7/08; G11B7/09; G11B7/0908; G11B7/0916
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
87 words
A partial beam focus sensing device comprising: a lens element (20:30;40;70) for receiving a collimated light beam (12) representative of light reflected from optical recording media, and a light detector array (26;46:76), characterised by a centrally symmetric mask element (16;100) adjacent to said lens element for eliminating a portion of said light beam and transmitting a partial light beam, the light detector array comprising at least two light detecting elements (26a,26b;46a,46b) matched to said mask element and disposed to receive said partial beam from said lens element.
Claim 2
Dependent Claim
87 words
A partial beam focus sensing device comprising: a lens element (20:30;40;70) for receiving a collimated light beam (12) representative of light reflected from optical recording media, and a light detector array (26;46:76), characterised by a centrally symmetric mask element (16;100) adjacent to said lens element for eliminating a portion of said light beam and transmitting a partial light beam, the light detector array comprising at least two light detecting elements (26a,26b;46a,46b) matched to said mask element and disposed to receive said partial beam from said lens element.
Claim 3
Dependent Claim
19 words
A device as claimed in claim 1 characterised in that said lens element is a spherical Fresnel lens (30).
Claim 4
Dependent Claim
18 words
A device as claimed in claim 1 characterised in that said lens element is a cylindrical lens (40).
Claim 5
Dependent Claim
31 words
A device as claimed in claim 3 characterised in that said light detector array (46) is disposed at an angle (0) with respect to the axis (50) of said cylindrical lens.
Claim 6
Dependent Claim
19 words
A device as claimed in claim 1 characterised in that said lens element is a cylindrical Fresnel lens (70).
Claim 7
Dependent Claim
30 words
A device as claimed in claim 5 characterised in that said light detector array (76) is disposed at an angle with respect to the axis of said cylindrical Fresnel (70).
Claim 8
Independent Claim
19 words
A device as claimed in any preceding claim characterised in that said mask element (16) is a knife edge.
Claim 9
Independent Claim
44 words
A device as claimed in any of claims 1 to 6 characterised in that said mask element (100) has a plurality of spokes radiating from a centre to divide the light beam into a number of segments, alternate ones blocking light from passing therethrough.
References Cited (Backward Citations)
No citation records indexed.
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