US5049732A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optical pickup device with diffraction device
Assignee: Sharp Corp
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Filing: 1989-10-19
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Granted: 1991-09-17
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Expires: 2009-10-19
Abstract
Abstract An optical pickup device in which a main beam and a pair of sub-beams are used and a diffraction device is disposed between a recording medium and a light receiving device such as a photodetector is disclosed. The diffraction device comprises first to third diffraction regions. The second and third regions receive light beams from the recording medium which are substantially identical in amount to each other. The light receiving device comprises a first to a fourth light receiving regions. The first and second light receiving regions are juxtaposed, and separated by a line. The main beam which has been diffracted by the first diffraction region is focused onto said line. The main beam which has been diffracted by the second diffraction region is focused onto the first light receiving region. The main beam which has been diffracted by the third diffracting region is focused onto the second light receiving region. The sub-beams which have been diffracted by the diffraction device are focused onto the third and fourth light receiving regions, respectively. Alternatively, the diffraction device comprises an area where one or more diffraction regions are formed. The farthest point of the area at the side of the light receiving device is separated from the optical axis by a predetermined distance, to prevent the first order diffracted beam from entering the optical system disposed between the diffraction device and a recording medium.
Inventors
- 👤 Toshiya Nagahama
- 👤 Yoshio Yoshida
- 👤 Yasuo Nakata
- 👤 Yukio Kurata
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 08:19
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/12; G11B7/135; G11B7/1381; G11B7/08; G11B7/09; G11B7/0908; G11B7/0916; G11B7/1353
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
182 words
In an optical pickup device wherein a main beam and a pair of sub-beams are reflected from a recording medium, and directed to a light receiving device through a diffraction device, the improvement wherein: said diffraction device comprises first, second and third diffraction regions which diffract the main beams and sub-beams along predetermined diffraction directions, said second and third diffraction regions receiving light beams from said recording medium which are substantially identical in amount to each other, said light receiving device comprises first, second, third and fourth receiving regions, said first and second light receiving regions being juxtaposed, and separated by a line, the main beam which has been diffracted by said first diffraction region is focused onto said line, the main beam which has been diffracted by said second diffraction region is focused onto said first light receiving region, the main beam which has been diffracted by said third diffraction region is focused onto said second light receiving region, and the sub-beams which have been diffracted by said diffraction device are focused onto said third and fourth light receiving regions, respectively.
Claim 2
Dependent Claim
182 words
In an optical pickup device wherein a main beam and a pair of sub-beams are reflected from a recording medium, and directed to a light receiving device through a diffraction device, the improvement wherein: said diffraction device comprises first, second and third diffraction regions which diffract the main beams and sub-beams along predetermined diffraction directions, said second and third diffraction regions receiving light beams from said recording medium which are substantially identical in amount to each other, said light receiving device comprises first, second, third and fourth receiving regions, said first and second light receiving regions being juxtaposed, and separated by a line, the main beam which has been diffracted by said first diffraction region is focused onto said line, the main beam which has been diffracted by said second diffraction region is focused onto said first light receiving region, the main beam which has been diffracted by said third diffraction region is focused onto said second light receiving region, and the sub-beams which have been diffracted by said diffraction device are focused onto said third and fourth light receiving regions, respectively.
Claim 3
Dependent Claim
34 words
An optical pickup device according to claim 1, wherein said line extends along a direction which substantially coincides with the diffraction direction along which said main beam is diffracted in said first diffraction region.
Claim 4
Dependent Claim
20 words
An optical pickup device according to claim 1, wherein said diffraction regions are different in grating period from each other.
Claim 5
Dependent Claim
16 words
An optical pickup device according to claim 1, wherein said diffraction device has a circular shape.
Claim 6
Dependent Claim
33 words
An optical pickup device according to claim 4, wherein said first diffraction region is formed into a semicircular shape, and said second and third diffracting regions are formed into a quadrant shape, respectively.
Claim 7
Dependent Claim
24 words
An optical pickup device according to claim 1, wherein gratings of said first, second and third diffraction gratings are not parallel to each other.
Claim 8
Dependent Claim
26 words
An optical pickup device according to claim 6, wherein gratings of said second and third diffraction regions extend at opposite angles with respect to said line.
Claim 9
Dependent Claim
47 words
An optical pickup device according to claim 4, wherein said first diffraction region is formed into a semicircular shape, said second and third diffracting regions share a semicircle, and said second diffracting region is formed into a strip-like shape positioned between said first and third diffraction regions.
Claim 10
Dependent Claim
154 words
In an optical pickup device comprising: a light source; a diffraction device; an optical system disposed between said diffraction device and a recording medium, said optical system focusing light beams from said light source onto said recording medium, said optical system directing light beams reflected from said recording medium to said diffraction device; and a light receiving device which is spaced transversely from the optical axis of the device and receives light beams from said diffraction device, the improvement wherein: said diffraction device comprises an area where one or more diffraction regions are formed, said area having a first side and a second side with the first side being transversely nearer the receiving device than the second side, the first side of said area being separated from said optical axis by a predetermined distance, and the second side being separated from said optical axis by a distance which is greater than said predetermined distance.
Claim 11
Dependent Claim
154 words
In an optical pickup device comprising: a light source; a diffraction device; an optical system disposed between said diffraction device and a recording medium, said optical system focusing light beams from said light source onto said recording medium, said optical system directing light beams reflected from said recording medium to said diffraction device; and a light receiving device which is spaced transversely from the optical axis of the device and receives light beams from said diffraction device, the improvement wherein: said diffraction device comprises an area where one or more diffraction regions are formed, said area having a first side and a second side with the first side being transversely nearer the receiving device than the second side, the first side of said area being separated from said optical axis by a predetermined distance, and the second side being separated from said optical axis by a distance which is greater than said predetermined distance.
References Cited (Backward Citations)
US4143402A
Cited
US4733065A
Cited
US4888752A
Cited
US4665310A
Cited
EP0228620A2
Cited
US4817074A
Cited
US4731772A
Cited
US4817072A
Cited
US4768183A
Cited
EP0273356A2
Cited
US4829506A
Cited
US4904856A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-09-16 | 1995-03-18 | 1995-09-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-09-16 | 1999-03-18 | 1999-09-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-09-16 | 2003-03-18 | 2003-09-17 | $7700.00 | Window Closed / Lapsed |