# US 2008/0186833 A1 · Optical pickup device and optical disk apparatus

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- Number: US 2008/0186833 A1
- Document ID: US20080186833A1
- Status: Published application
- Kind: A1
- Application number: 12/024,278
- Filed: 2008-02-01
- Published: 2008-08-07
- Earliest claimed: 2007-02-01
- Assignees: Sanyo Electric Co., Ltd.; Sanyo Optec Design Co., Ltd.
- Inventors: Kenji Nagatomi; Yasuyuki Kano
- Web page: https://patentgrep.com/patent/US20080186833A1

## CPC

- G11B 7/0943: {Methods and circuits for performing mathematical operations on individual detector segment outputs}
- G11B 7/1365: Separate or integrated refractive elements, e.g. wave plates
- G11B 7/1374: Objective lenses {(optical objectives per se G02B9/00)}
- G11B 7/13925: {active, e.g. controlled by electrical or mechanical means}
- G11B 7/1395: Beam splitters or combiners (G11B7/1353, G11B7/1356 take precedence {; beam splitting or combining per se G02B27/10})
- G11B 2007/0006: {adapted for scanning different types of carrier, e.g. CD & DVD}
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)

## Abstract

A half-wave plate is attached to a lens holder to integrally drive a collimator lens and the half-wave plate. When the lens holder is moved to a servo position, the half-wave plate is inserted in and retracted from an optical path of a laser beam. Therefore, the laser beam is formed in S-polarized light or P-polarized light with respect to a polarization beam splitter, and the laser beam is guided to a first objective lens or a second objective lens.

## Claims

### Claim 1

An optical pickup device comprising:
a laser source which emits a laser beam having a predetermined wavelength;
first and second objective lenses which cause the laser beam to converge onto a recording medium;
a polarization beam splitter which is disposed between the laser source and the first and second objective lenses;
first and second optical systems which guide the two laser beams split by the polarization beam splitter to the first and second objective lenses respectively;
first and second optical elements which are disposed in the first and second optical systems respectively, the first and second optical elements being moved in optical axis directions of the laser beams to adjust optical characteristics of the laser beams respectively;
a first actuator which supports a first holder holding the first optical element while the first holder can be displaced in the optical axis direction of the laser beam;
a second actuator which supports a second holder holding the second optical element while the second holder can be displaced in the optical axis direction of the laser beam;
a driving portion which imparts a driving force to the first actuator;
a transfer mechanism which transfers the driving force to the second actuator such that a drive stroke is smaller than that of the first actuator; and
a wave plate which is inserted in and retracted from an optical path between the laser source and the polarization beam splitter to change the polarization direction of the laser beam incident to the polarization beam splitter,
wherein the first and second optical elements are moved in a direction in which the wave plate is inserted and retracted,
the wave plate is disposed in a support portion integral with the first holder,
the first actuator moves the first holder in both a first stroke for optical characteristic adjustment with the first optical element and a second stroke exceeding the first stroke,
the first holder is moved between the first stroke and the second stroke to insert and retract the wave plate in and from the optical path,
the polarization direction of the laser beam incident to the polarization beam splitter is adjusted such that the laser beam is guided to the first optical system, when the first holder is located in the first stroke, and
the second holder is located in the stroke for optical characteristic adjustment with the second optical element while the polarization direction of the laser beam incident to the polarization beam splitter is adjusted such that the laser beam is guided to the second optical system, when the first holder is located in the second stroke.

### Claim 2 (depends on 1)

The optical pickup device according to claim 1, wherein the first and second optical elements are lenses for correcting aberration generated in the laser beam.

### Claim 3 (depends on 1)

The optical pickup device according to claim 1, wherein the wave plate includes first and second wave plate regions where the laser beam is formed in P-polarized light and S-polarized light with respect to the polarization beam splitter, and
a target inserted in the optical path is switched between the first and second wave plate regions based on whether the first holder is located in the first stroke or the second stroke.

### Claim 4 (depends on 1)

The optical pickup device according to claim 1, wherein the polarization direction of the laser beam becomes P-polarized light or S-polarized light with respect to the polarization beam splitter before being incident to the wave plate,
the wave plate includes a wave plate region where the polarization direction of the laser beam is rotated by about 90° and a transparent plate region having a thickness of an optical path length identical to that of the wave plate region, and
a target inserted in the optical path is switched between the wave plate region and the transparent plate region based on whether the first holder is located in the first stroke or the second stroke.

### Claim 5

An optical disk apparatus comprising:
an optical pickup device; and
a servo circuit which controls the optical pickup device,
wherein the optical pickup device including:
a laser source which emits a laser beam having a predetermined wavelength;
first and second objective lenses which cause the laser beam to converge onto a recording medium;
a polarization beam splitter which is disposed between the laser source and the first and second objective lenses,
first and second optical systems which guide the two laser beams split by the polarization beam splitter to the first and second objective lenses respectively;
first and second optical elements which are disposed in the first and second optical systems respectively, the first and second optical elements being moved in optical axis directions of the laser beams to adjust optical characteristics of the laser beams respectively;
a first actuator which supports a first holder holding the first optical element while the first holder can be displaced in the optical axis direction of the laser beam;
a second actuator which supports a second holder holding the second optical element while the second holder can be displaced in the optical axis direction of the laser beam;
a driving portion which imparts a driving force to the first actuator;
a transfer mechanism which transfers the driving force to the second actuator such that a drive stroke is smaller than that of the first actuator; and
a wave plate which is inserted in and retracted from an optical path between the laser source and the polarization beam splitter to change the polarization direction of the laser beam incident to the polarization beam splitter,
wherein the first and second optical elements are moved in a direction in which the wave plate is inserted and retracted,
the wave plate is disposed in a support portion integral with the first holder,
the first actuator moves the first holder in both a first stroke for optical characteristic adjustment with the first optical element and a second stroke exceeding the first stroke,
the first holder is moved between the first stroke and the second stroke to insert and retract the wave plate in and from the optical path,
the polarization direction of the laser beam incident to the polarization beam splitter is adjusted such that the laser beam is guided to the first optical system, when the first holder is located in the first stroke, and
the second holder is located in the stroke for optical characteristic adjustment with the second optical element while the polarization direction of the laser beam incident to the polarization beam splitter is adjusted such that the laser beam is guided to the second optical system, when the first holder is located in the second stroke, and
wherein the servo circuit controls the driving portion to adjust the optical characteristics of the laser beams incident to the first and second objective lenses, and the servo circuit controls whether the laser beam is guided to the first or second optical system.

### Claim 6 (depends on 5)

The optical disk apparatus according to claim 5, wherein the first and second optical elements are lenses for correcting aberration generated in the laser beam.

### Claim 7 (depends on 5)

The optical disk apparatus according to claim 5, wherein the wave plate includes first and second wave plate regions where the laser beam is formed in P-polarized light and S-polarized light with respect to the polarization beam splitter, and
a target inserted in the optical path is switched between the first and second wave plate regions based on whether the first holder is located in the first stroke or the second stroke.

### Claim 8 (depends on 5)

The optical disk apparatus according to claim 5, wherein the polarization direction of the laser beam becomes P-polarized light or S-polarized light with respect to the polarization beam splitter before being incident to the wave plate,
the wave plate includes a wave plate region where the polarization direction of the laser beam is rotated by about 90° and a transparent plate region having a thickness of an optical path length identical to that of the wave plate region, and
a target inserted in the optical path is switched between the wave plate region and the transparent plate region based on whether the first holder is located in the first stroke or the second stroke.