EP0838812A2
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EP
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Method for recording/reproducing on/from an optical information recording medium, optical pickup apparatus, objective lens and design method of objective lens
Assignee: Konica Minolta Inc
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Filing: 1997-10-17
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Granted: —
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Expires: 2017-10-17
Abstract
Abstract An optical pickup apparatus includes a light source for emitting a light flux; and a converging optical system having a first, second, and third divided surface, which are divided in the order named from the vicinity of an optical axis of the converging optical system, for converging the light flux emitted from the light source, wherein a beam spot passing through the first and third divided surfaces is formed onto a first optical information recording medium having a transparent substrate whose thickness is t1, and a beam spot passing through the first and second surfaces is formed onto a second optical information recording medium having a transparent substrate whose thickness is t2 that is more than t1. The optical pickup apparatus further includes an image sensor for receiving a light flux reflected from the first and/or second optical information recording medium.
Inventors
- 👤 Norikazu Arai
- 👤 Hiroyuki Yamazaki
- 👤 Shinichiro Saito
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 02:16
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/12; G11B7/125; G11B7/127; G11B7/1275; G02; G02B; G02B13/00; G02B3/00; G02B3/10; G11B7/135; G11B7/1353; G11B7/1365; G11B7/1367; G11B7/1372; G11B7/1374; G11B7/1381; G11B7/139; G11B7/1392; G11B7/13922; G11B2007/0003; G11B2007/0006; G11B2007/13727
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
138 words
An optical pickup apparatus comprising: (a) a light source for emitting a light flux; (b) a converging optical system having a first, second,
and third divided surface, which are divided in the order
named from the vicinity of an optical axis of the converging
optical system, for converging the light flux emitted from the
light source, wherein a beam spot passing through the first and third
divided surfaces is formed onto a first optical information
recording medium having a transparent substrate whose
thickness is t1, and a beam spot passing through the first and
second surfaces is formed onto a second optical information
recording medium having a transparent substrate whose
thickness is t2 that is more than t1; and (c) an image sensor for receiving a light flux reflected
from the first or second optical information recording medium.
Claim 2
Dependent Claim
55 words
The optical pickup apparatus of claim 1, wherein an
angle between a normal line at a central position on the
second divided surface and the optical axis is larger than an
angle between a normal line at a central position of a surface
interpolated from the first and third divided surfaces and the
optical axis.
Claim 3
Dependent Claim
49 words
The optical pickup apparatus of claim 1, wherein a
beam spot is formed on the first optical information recording
medium, in a spherical aberration chart, a spherical
aberration curve according to the second divided surface is
positioned under than a spherical aberration curve according
to the first divided surface.
Claim 4
Dependent Claim
70 words
The optical pickup apparatus of claim 1, wherein the
following conditional expression is satisfied: 0.60·NA2 < NAL < 1.30·NA2 where NA2 represents a numerical aperture on a side of the
second optical information recording medium of the converging
optical system required for recording or reproducing
information on the second optical information recording medium,
and NAL represents a numerical aperture in a border portion
between the first and second divided surfaces.
Claim 5
Dependent Claim
94 words
The optical pickup apparatus of claim 1, wherein the
following conditional expressions are satisfied: 0.60·NA2 < NAL < 1.30·NA2 and 0.01 < NAH - NAL < 0.12 where NA2 represents a numerical aperture on a side of the
second optical information recording medium of the converging
optical system required for recording or reproducing
information on the second optical information recording medium,
NAL represents a numerical aperture in a border portion
between the first and second divided surfaces, and NAH
represents a numerical aperture in a border portion between
the second and third divided surfaces.
Claim 6
Dependent Claim
20 words
The optical pickup apparatus of claim 1, wherein the
first, second and third divided surfaces are formed on
concentric circles.
Claim 7
Dependent Claim
112 words
An objective lens for use in an optical pickup
apparatus, comprising an optical surface which is divided, in the order named
from the vicinity of an optical axis of the objective lens,
into a first, second and third divided surfaces for converging
a light flux emitted from a light source, wherein a beam spot passing through the first and third
divided surfaces is formed onto a first optical information
recording medium having a transparent substrate whose
thickness is t1, and a beam spot passing through the first and
second surfaces is formed onto a second optical information
recording medium having a transparent substrate whose
thickness is t2 that is more than t1.
Claim 8
Dependent Claim
54 words
The objective lens of claim 7, wherein an angle
between a normal line at a central position on the second
divided surface and the optical axis is larger than an angle
between a normal line at a central position of a surface
interpolated from the first and third divided surfaces and the
optical axis.
Claim 9
Dependent Claim
48 words
The objective lens of claim 7, wherein a beam spot is
formed on the first optical information recording medium, in a
spherical aberration chart, a spherical aberration curve
according to the second divided surface is positioned under
than a spherical aberration curve according to the first
divided surface.
Claim 10
Dependent Claim
69 words
The objective lens of claim 7, wherein the following
conditional expression is satisfied: 0.60·NA2 < NAL < 1.30·NA2 where NA2 represents a numerical aperture on a side of the
second optical information recording medium of the converging
optical system required for recording or reproducing
information on the second optical information recording medium,
and NAL represents a numerical aperture in a border portion
between the first and second divided surfaces.
Claim 11
Dependent Claim
93 words
The objective lens of claim 7, wherein the following
conditional expressions are satisfied: 0.60·NA2 < NAL < 1.30·NA2 and 0.01 < NAH - NAL < 0.12 where NA2 represents a numerical aperture on a side of the
second optical information recording medium of the converging
optical system required for recording or reproducing
information on the second optical information recording medium,
NAL represents a numerical aperture in a border portion
between the first and second divided surfaces, and NAH
represents a numerical aperture in a border portion between
the second and third divided surfaces.
Claim 12
Dependent Claim
19 words
The objective lens of claim 7, wherein the first,
second and third divided surfaces are formed on concentric
circles.
References Cited (Backward Citations)
No citation records indexed.
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