Patent EP0409468A2 successfully refreshed from Google Patents.
EP0409468A2
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EP
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Flying optical head
Assignee: Panasonic Holdings Corp
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Filing: 1990-07-10
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Granted: —
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Expires: 2010-07-10
Abstract
Abstract Disclosed is an optical head of small size and light weight flying to float relative to a signal recording and reproducing surface (18) of an optical disk (1), thereby recording and reproducing an information signal on and from the signal recording and reproducing surface (18) of the optical disk (1) with a high density by focusing a laser beam by using an objective lens (21, 31) having a large numerical aperture NA. Disclosed also is an optical information recording and reproducing apparatus using the optical head for information signal recording and reproduction. The optical head comprises a fixed optical part (2) including a laser beam source (6), a collimation lens (7), a reflected beam splitter (8) and a photo detector (11), a moving optical part (19) including a beam reflector (20), an objective lens (21, 31) and a slider (22) mounting the beam reflector (20) and the objective lens (21) thereon and flying to float the objective lens relative to a signal recording and reproducing surface (18) of an optical disk (1), and an actuating element (23, 32, 28, 35) mounted on either the objective lens (21, 31) or the collimation lens (7), or an actuating element (26) for driving a flexure (24) connecting the slider (22) to a linear motor (25), or a lens part (40) for changing the position of the beam emission point of the laser beam source (6). The slider (22) mounting the objective lens (21, 31) thereon flies to float the objective lens (21, 31) relative to the signal recording and reproducing surface (18) of the optical disk (1) through a gaseous layer, and fluctuation of the flying height of the slider (22) is limited to a value smaller than about several um substantially independently of vertical runout of the signal recording and reproducing surface (18) of the optical disk (1), so that the movable distance of the objective lens (21, 31) required for the focus control can be mimized. Therefore, the laser beam can be focused into a diffraction-limited beam spot by using the objective lens (21, 31) having a large numerical aperture NA, so that the optical head of the small size and light weight can detect a substantially offsetless servo error signal. Thus, a large-capacity memory device having a stacked structure permitting high-speed track access can be provided.
Inventors
- 👤 Isao Satoh
- 👤 Sadao Mizuno
- 👤 Noboru Yamada
- 👤 Yasuhiro Gotoh
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 02:57
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/12; G11B7/125; G11B7/127; G11B7/08; G11B7/085; G11B7/0857; G11B7/08582; G11B7/122; G11B7/135; G11B7/1384
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
279 words
An optical head comprising: a source (6) of a laser beam; beam condensing means (7) including a collimation lens for collimating the laser beam emitted from said laser beam source (6); beam reflecting means (20) for reflecting the collimated laser beam so as to direct the collimated laser beam in a direction substantially perpendicular to a signal recording and reproducing surface (18) of an optical disk (1); an objective lens (21) for focusing the laser beam reflected from said beam reflecting means (20) on said signal recording and reproducing surface (18) of said optical disk (1); beam splitting means (8, 9) for splitting the reflected laser beam from said signal recording and reproducing surface (18) of said optical disk (1); beam detecting means (11) for receiving and detecting the reflected laser beam split by said beam splitting means (8, 9); a fixed optical part (2) including said laser beam source and said beam condensing means (7) therein; an actuating element (23) for causing a slight movement of said objective lens (21) fixed to said actuating element (23) in the direction of the optical axis of said objective lens (21); and a slider (22) mounting thereon said beam reflecting means (20), said actuating element (23) and said objective lens (21), said slider flying to float said objective lens (21) relative to said signal recording and reproducing surface (18) of said optical disk (1) through a gaseous layer, and said objective lens (21) mounted on said flying slider (22) being actuated by said actuating element (23) until the laser beam is just focused by said objective lens (21) on said signal recording and reproducing surface (18) of said optical disk (1).
Claim 2
Dependent Claim
279 words
An optical head comprising: a source (6) of a laser beam; beam condensing means (7) including a collimation lens for collimating the laser beam emitted from said laser beam source (6); beam reflecting means (20) for reflecting the collimated laser beam so as to direct the collimated laser beam in a direction substantially perpendicular to a signal recording and reproducing surface (18) of an optical disk (1); an objective lens (21) for focusing the laser beam reflected from said beam reflecting means (20) on said signal recording and reproducing surface (18) of said optical disk (1); beam splitting means (8, 9) for splitting the reflected laser beam from said signal recording and reproducing surface (18) of said optical disk (1); beam detecting means (11) for receiving and detecting the reflected laser beam split by said beam splitting means (8, 9); a fixed optical part (2) including said laser beam source and said beam condensing means (7) therein; an actuating element (23) for causing a slight movement of said objective lens (21) fixed to said actuating element (23) in the direction of the optical axis of said objective lens (21); and a slider (22) mounting thereon said beam reflecting means (20), said actuating element (23) and said objective lens (21), said slider flying to float said objective lens (21) relative to said signal recording and reproducing surface (18) of said optical disk (1) through a gaseous layer, and said objective lens (21) mounted on said flying slider (22) being actuated by said actuating element (23) until the laser beam is just focused by said objective lens (21) on said signal recording and reproducing surface (18) of said optical disk (1).
Claim 3
Dependent Claim
17 words
An optical head according to Claim 1, wherein said actuating element is an annular piezoelectric element (23).
Claim 4
Dependent Claim
248 words
An optical head comprising: a source (6) of a laser beam; beam condensing means (7) including a collimation lens for collimating the laser beam emitted from said laser beam source (6); beam reflecting means (20) for reflecting the collimated laser beam so as to direct the collimated laser beam in a direction substantially perpendicular to a signal recording and reproducing surface (18) of an optical disk (1); an objective lens (21) for focusing the laser beam reflected from said beam reflecting means (20) on said signal recording and reproducing surface (18) of said optical disk (1); beam splitting means (8, 9) for splitting the reflected laser beam from said signal recording and reproducing surface (18) of said optical disk (1); beam detecting means (11) for receiving and detecting the reflected laser beam split by said beam splitting means (8, 9); a fixed optical part (2) including said laser beam source (6) and said beam condensing means (7) therein; an actuating element (28) having said collimation lens mounted thereon; a slider (22) mounting said objective lens (21) and said beam reflecting means (20) thereon, said slider flying to float said objective lens (21) relative to said signal recording and reproducing surface (18) of said optical disk (1) through a gaseous layer, and said collimation lens being driven in the direction of its optical axis until the laser beam is just focused by said objective lens (21) on said signal recording and reproducing surface (18) of said optical disk (1).
Claim 5
Dependent Claim
248 words
An optical head comprising: a source (6) of a laser beam; beam condensing means (7) including a collimation lens for collimating the laser beam emitted from said laser beam source (6); beam reflecting means (20) for reflecting the collimated laser beam so as to direct the collimated laser beam in a direction substantially perpendicular to a signal recording and reproducing surface (18) of an optical disk (1); an objective lens (21) for focusing the laser beam reflected from said beam reflecting means (20) on said signal recording and reproducing surface (18) of said optical disk (1); beam splitting means (8, 9) for splitting the reflected laser beam from said signal recording and reproducing surface (18) of said optical disk (1); beam detecting means (11) for receiving and detecting the reflected laser beam split by said beam splitting means (8, 9); a fixed optical part (2) including said laser beam source (6) and said beam condensing means (7) therein; an actuating element (28) having said collimation lens mounted thereon; a slider (22) mounting said objective lens (21) and said beam reflecting means (20) thereon, said slider flying to float said objective lens (21) relative to said signal recording and reproducing surface (18) of said optical disk (1) through a gaseous layer, and said collimation lens being driven in the direction of its optical axis until the laser beam is just focused by said objective lens (21) on said signal recording and reproducing surface (18) of said optical disk (1).
Claim 6
Dependent Claim
17 words
An optical head according to Claim 3, wherein said actuating element is an annular piezoelectric element (28).
Claim 7
Dependent Claim
300 words
An optical head comprising: a source (6) of a laser beam; beam condensing means (7) including a collimation lens for collimating the laser beam emitted from said laser beam source (6); beam reflecting means (20) for reflecting the collimated laser beam so as to direct the collimated laser beam in a direction substantially perpendicular to a signal recording and reproducing surface (18) of an optical disk (1); an objective lens (21) for focusing the laser beam reflected from said beam reflecting means (20) on said signal recording and reproducing surface (18) of said optical disk (1); beam splitting means (8, 9) for splitting the reflected laser beam from said signal recording and reproducing surface (18) of said optical disk (1); beam detecting means (11) for receiving and detecting the reflected laser beam split by said beam splitting means (8, 9); a fixed optical part (2) including said laser beam source (6) and said beam condensing means (7) therein; movable optical means (19) including a slider (22) mounting said objective lens (21) and said beam reflecting means (20) thereon; feeding means (25) for feeding said movable optical means (19) in a radial direction of said optical disk (1); a flexure (24) for fixing said movable optical means (19) to said feeding means (25); and an actuating element (26) for bending said flexure (24); said slider (22) flying to float said objective lens (21) relative to said signal recording and reproducing surface (18) of said optical disk (1) through a gaseous layer, and said actuating element (26) causing said flexure (24) to bend, thereby moving said objective lens (21) mounted on said flying slider (22) in the direction of its optical axis until the laser beam is just focused on said signal recording and reproducing surface (18) of said optical disk (1).
Claim 8
Dependent Claim
300 words
An optical head comprising: a source (6) of a laser beam; beam condensing means (7) including a collimation lens for collimating the laser beam emitted from said laser beam source (6); beam reflecting means (20) for reflecting the collimated laser beam so as to direct the collimated laser beam in a direction substantially perpendicular to a signal recording and reproducing surface (18) of an optical disk (1); an objective lens (21) for focusing the laser beam reflected from said beam reflecting means (20) on said signal recording and reproducing surface (18) of said optical disk (1); beam splitting means (8, 9) for splitting the reflected laser beam from said signal recording and reproducing surface (18) of said optical disk (1); beam detecting means (11) for receiving and detecting the reflected laser beam split by said beam splitting means (8, 9); a fixed optical part (2) including said laser beam source (6) and said beam condensing means (7) therein; movable optical means (19) including a slider (22) mounting said objective lens (21) and said beam reflecting means (20) thereon; feeding means (25) for feeding said movable optical means (19) in a radial direction of said optical disk (1); a flexure (24) for fixing said movable optical means (19) to said feeding means (25); and an actuating element (26) for bending said flexure (24); said slider (22) flying to float said objective lens (21) relative to said signal recording and reproducing surface (18) of said optical disk (1) through a gaseous layer, and said actuating element (26) causing said flexure (24) to bend, thereby moving said objective lens (21) mounted on said flying slider (22) in the direction of its optical axis until the laser beam is just focused on said signal recording and reproducing surface (18) of said optical disk (1).
Claim 9
Dependent Claim
57 words
An optical head according to Claim 5, wherein said actuating element (26) comprises a pair of piezoelectric elements bonded to the front and back surfaces respectively of said flexure (24), and said piezoelectric elements are energized differentially to cause bending of said flexure (24), thereby moving said objective lens (21) in the direction of its optical axis.
Claim 10
Dependent Claim
193 words
An optical head comprising: a source (6) of a laser beam; beam condensing means (7) including a collimation lens for collimating the laser beam emitted from said laser beam source (6); beam focusing means (31) for focusing the collimated laser beam on a signal recording and reproducing surface (18) of an optical disk (1); beam splitting means (8, 9) for splitting the reflected laser beam from said signal recording and reproducing surface (18) of said optical disk (1); beam detecting means (11) for receiving and detecting the reflected laser beam split by said beam splitting means (8, 9); an optical fiber (30) for transmitting the collimated laser beam toward said beam focusing means (31); and a slider (22) mounting said optical fiber (30) and said beam focusing means (31) thereon, said slider (22) flying to float said beam focusing means (31) relative to said signal recording and reproducing surface (18) of said optical disk (1) through a gaseous layer, whereby a signal is recorded and reproduced on and from said signal recording and reproducing surface (18) of said optical disk (1) by the laser beam focused thereon by said beam focusing means (31).
Claim 11
Dependent Claim
193 words
An optical head comprising: a source (6) of a laser beam; beam condensing means (7) including a collimation lens for collimating the laser beam emitted from said laser beam source (6); beam focusing means (31) for focusing the collimated laser beam on a signal recording and reproducing surface (18) of an optical disk (1); beam splitting means (8, 9) for splitting the reflected laser beam from said signal recording and reproducing surface (18) of said optical disk (1); beam detecting means (11) for receiving and detecting the reflected laser beam split by said beam splitting means (8, 9); an optical fiber (30) for transmitting the collimated laser beam toward said beam focusing means (31); and a slider (22) mounting said optical fiber (30) and said beam focusing means (31) thereon, said slider (22) flying to float said beam focusing means (31) relative to said signal recording and reproducing surface (18) of said optical disk (1) through a gaseous layer, whereby a signal is recorded and reproduced on and from said signal recording and reproducing surface (18) of said optical disk (1) by the laser beam focused thereon by said beam focusing means (31).
Claim 12
Dependent Claim
79 words
An optical head according to Claim 7, further comprising an actuating element (32) for moving said beam focusing means (31) together with a terminating end of said optical fiber (30) in the direction of the optical axis of said beam focusing means (31), said actuating element (32) driving said beam focusing means (31) until the laser beam is just focused by said beam focusing means (31) on said signal recording and reproducing surface (18) of said optical disk (1).
Claim 13
Dependent Claim
16 words
An optical head according to Claim 8, wherein said actuating element (32) is a piezoelectric element.
Claim 14
Dependent Claim
64 words
An optical head according to Claim 7, further comprising an actuating element (35) mounting said collimation lens in said beam condensing means (7), said actuating element (35) driving said collimation lens in the direction of its optical axis until the laser beam is just focused by said beam focusing means (31) on said signal recording and reproducing surface (18) of said optical disk (1).
Claim 15
Dependent Claim
16 words
An optical head according to Claim 10, wherein said actuating element (35) is a piezoelectric element.
Claim 16
Dependent Claim
32 words
An optical head according to Claim 7, wherein a terminating end of said optical fiber (30) has been worked to have a spherical surface to act as said beam focusing means (31).
Claim 17
Dependent Claim
19 words
An optical head according to Claim 7 wherein said optical fiber (30) is a self-focusing type optical fiber (33).
Claim 18
Dependent Claim
29 words
An optical head according to Calim 13, wherein the lens function of said self-focusing type optical fiber (33) is utilized to be substituted for said beam focusing means (31).
Claim 19
Dependent Claim
29 words
An optical head according to Calim 13, wherein the lens function of said self-focusing type optical fiber (33) is utilized to be substituted for said beam focusing means (31).
Claim 20
Dependent Claim
207 words
An optical information recording and reproducing apparatus comprising: a source (37) of a laser beam; means (40) for changing the position of the beam emission point of said laser beam source (37); beam condensing means (7) including a collimation lens for collimating the laser beam emitted from said laser beam source (37); beam focusing means (21) for focusing the collimated laser beam on a signal recording and reproducing surface (18) of an optical disk (1); beam splitting means (8, 9) for splitting the reflected laser beam from said signal recording and reproducing surface (18) of said optical disk (1); beam detecting means (11) for receiving and detecting the reflected laser beam split by said beam splitting means (8, 9); and a slider (22) mounting said beam focusing means (21) thereon, said slider (22) flying to float said beam focusing means (21) relative to said signal recording and reproducing surface (18) of said optical disk (1) through a gaseous layer; said beam emission point position changing means (40) changing the position of the beam emission point of said laser beam source (37) until the laser beam is just focused by said beam focusing means (21) on said signal recording and reproducing surface (18) of said optical disk (1).
Claim 21
Dependent Claim
207 words
An optical information recording and reproducing apparatus comprising: a source (37) of a laser beam; means (40) for changing the position of the beam emission point of said laser beam source (37); beam condensing means (7) including a collimation lens for collimating the laser beam emitted from said laser beam source (37); beam focusing means (21) for focusing the collimated laser beam on a signal recording and reproducing surface (18) of an optical disk (1); beam splitting means (8, 9) for splitting the reflected laser beam from said signal recording and reproducing surface (18) of said optical disk (1); beam detecting means (11) for receiving and detecting the reflected laser beam split by said beam splitting means (8, 9); and a slider (22) mounting said beam focusing means (21) thereon, said slider (22) flying to float said beam focusing means (21) relative to said signal recording and reproducing surface (18) of said optical disk (1) through a gaseous layer; said beam emission point position changing means (40) changing the position of the beam emission point of said laser beam source (37) until the laser beam is just focused by said beam focusing means (21) on said signal recording and reproducing surface (18) of said optical disk (1).
Claim 22
Dependent Claim
55 words
An optical information recording and reproducing apparatus according to Claim 15, wherein said beam emission point position changing means is a lens part (40) integrated with a laser oscillation part (39) to form a laser diode (37), and said lens part (40) acts to change the beam waist position (d) of the emitted laser beam.
Claim 23
Dependent Claim
61 words
An optical information recording and reproducing apparatus according to Claim 15, wherein said optical disk (1) has recording tracks, a signal recording layer and a protective layer for protecting said signal recording layer formed on a surface of a disk substrate, and an information signal is recorded and reproduced on and from said signal recording layer of said optical disk (1).
References Cited (Backward Citations)
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