Patent EP0439876A1 successfully refreshed from Google Patents.
EP0439876A1
Expired / Lapsed
EP
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Optical head with a double-beam splitter
Assignee: Maxell Ltd
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Filing: 1990-01-29
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Granted: —
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Expires: 2010-01-29
Abstract
Abstract An optical recording medium driving apparatus is disclosed which comprises a light source (1), an objective lens (6) for focusing light onto a reflecting surface (11a) of the recording medium, a beam splitter (41) for separating reflective convergent beam, and detectors (9, 10) for detecting separated beams of the reflective convergent beam flux. Two beam separation surfaces (41a,41b) are formed in the beam splitter and are located on an optical path extending from the light source to the objective lens. The two detectors are arranged corresponding to the respective beam separation surfaces of the beam splitter. The two detector are disposed so that one of the two separated beams of the reflective convergent beam flux is focused before one of the detectors and the other of the two separated beams is focused after the other of the detectors.
Inventors
- 👤 Hitoshi Watanabe
- 👤 Toshinori Sugiyama
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 06:30
CPC Classifications
G; G11; G11B; G11B11/00; G11B11/10; G11B11/105; G11B11/10532; G11B11/10541; G11B11/10543; G11B7/00; G11B7/08; G11B7/09; G11B7/0908; G11B7/0912; G11B7/12; G11B7/135; G11B7/1356
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
173 words
An optical recording medium driving apparatus having an optical pickup, comprising: a light source (1); an objective lens for focusing light onto a surface (11) of a recording layer in the recording medium, the surface (11) having an optical reflectivity; a beam splitter (41) for separating reflective convergent beam flux; and detector means (9, 10) for detecting separated beam of the reflective convergent beam flux; wherein two beam separation surfaces of said beam splitter (41) are arranged on an optical path of a divergent beam flux extending from said light source (1) to said objective lens (6); two detectors are arranged corresponding to the respective beam separation surfaces of said beam splitter; and said two detectors are disposed so that a first one of the two separated beams of the reflective convergent beam flux is focused to a point and then diverged before a first one of the detectors (9) and a second one of the two separated beams thereof is converged toward a point behind a second one of the detectors (10).
Claim 2
Dependent Claim
27 words
The optical recording medium driving apparatus according to claim 1, further comprising a 1/2 wavelength plate interposed between said two beam separation surfaces of said beam splitter.
Claim 3
Dependent Claim
40 words
The optical recording medium driving apparatus according to claim 1, wherein one of said two beam separation surfaces of said beam splitter, disposed closer to said objective lens is smaller in reflectivity than the other of said beam separation surfaces.
Claim 4
Dependent Claim
133 words
The optical recording medium driving apparatus according to claim 1, further comprising a collimator lens, said beam splitter including a composite beam splitter where the two beam separation surfaces are formed in different directions, wherein said composite beam splitter and said collimator lens are arranged in order from said light source on the optical path extending from said light source to said objective lens; said composite beam splitter and/or said light source is rotated so that a polarization plane of the light emitted from said light source is rotated at an angle of 45 degrees on the light axis relative to a parallel plane of said composite beam splitter of said composite beam splitter; and said two detectors are separately disposed in confronted relation to the different surfaces of said composite beam splitter.
Claim 5
Dependent Claim
92 words
The optical recording medium driving apparatus according to claim 1, further comprising an upwardly reflecting mirror and a 1/4 wavelength, said beam splitter including a composite beam splitter where the two beam separation surfaces are formed in the same direction, wherein said composite splitter, said upwardly reflecting mirror and said 1/4 wavelength plate are arranged in order from said light source on the optical path of a divergent beam extending from said light source to said objective lens; and said two detectors are disposed on one side of said composite beam splitter.
Claim 6
Dependent Claim
93 words
The optical recording medium driving apparatus according to claim 1, further comprising a 1/4 wavelength plate, said beam splitter including a composite beam splitter where the two beam separation surfaces are formed in the same direction and a 1/2 wavelength plate is interposed between said two beam separation surfaces, wherein said beam splitter and said 1/4 wavelength plate are arranged in order from said light source on the optical path extending from said light source to the objective lens; and said two detectors are arranged on one side of said composite beam splitter.
Claim 7
Dependent Claim
88 words
The optical recording medium driving apparatus according to claim 1, further comprising a 1/4 wavelength plate, said beam splitter including a composite beam splitter where the two beam separation surfaces are formed to define an angle of 90 degrees therebetween, wherein said composite beam splitter and said 1/4 wavelength plate are arranged in order from said light source on the optical path extending from said light source to said objective lens; and the two detectors are arranged on the opposite sides with respect to said composite beam splitter.
Claim 8
Dependent Claim
140 words
The optical recording medium driving apparatus according to claim 1, further comprising an upwardly reflecting mirror and a first 1/4 wavelength plate, said beam splitter including a composite beam splitter where the two beam separation surfaces are formed to define an angle of 90 degrees therebetween, wherein said composite beam splitter, said upwardly reflecting mirror and said 1/4 wavelength plate are arranged in order from the light source on the optical path of a divergent beam extending from the light source to the objective lens; said apparatus further comprising a second 1/4 wavelength plate and a reflective mirror both of which are disposed on a reflective optical path of the beam separation surface; and said two detectors are arranged on the opposite side to said second 1/4 wavelength plate and the reflective mirror with respect to said composite beam splitter.
Claim 9
Dependent Claim
37 words
The optical recording medium driving apparatus according to claim 1, further comprising a relay lens for reducing astigmatism, said relay lens being disposed on at least one of upstream and downstream sides of said composite beam splitter.
Claim 10
Dependent Claim
88 words
The optical recording medium driving apparatus according to claim 1, further comprising a collimator lens and a 1/4 wavelength plate, said beam splitter including a composite beam splitter where the two beam separation surfaces are formed in the same direction, wherein said composite beam splitter, said collimator lens and said 1/4 wavelength plate are arranged in order from the light source on the optical path extending from the light source to the objective lens; and said two detectors are arranged on one side of said composite beam splitter.
Claim 11
Dependent Claim
129 words
The optical recording medium driving apparatus according to claim 1, further comprising a collimator lens, said beam splitter including a composite beam splitter where the two beam separation surfaces are formed in the same direction wherein said composite beam splitter and said collimator lens are arranged in order from the light source on the optical path extending from the light source to the objective lens; said light source and/or said composite beam splitter are rotated so that a polarization surface of light emitted from said light source is rotated at an angle of 45 degrees on the light axis with respect to the parallel plane of said composite beam splitter of said composite beam splitter; and said two detectors are arranged on one side of said composite beam splitter.
Claim 12
Dependent Claim
20 words
The optical recording medium driving apparatus according to claim 1, wherein said two detectors is formed on a base plate.
Claim 13
Dependent Claim
19 words
The optical recording medium driving apparatus according to claim 1, wherein said light source includes a semiconductor laser source.
References Cited (Backward Citations)
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