OPTICAL-PICKUP HEAD DEVICE, AND METHOD AND APPARATUS FOR REPRODUCING OPTICAL STORAGE MEDIUM

Abstract

A light source outputs an optical beam. A condensing unit condenses the optical beam to a first information-recording layer. An optical detecting unit detects a reflected optical beam reflected from the optical storage medium. A limiting element inputs a first reflected optical beam reflected from the first information-recording layer to the optical detecting unit, and limits or shields an input of a second reflected optical beam reflected from a second information-recording layer to the optical detecting unit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic of an optical system in an optical-storage-medium reproducing apparatus according to a first embodiment of the present invention;

FIG. 2 is a schematic for explaining an optical beam condensed on an information-recording layer in a single-sided dual-layer optical disk according to the first embodiment;

FIG. 3 is a schematic for explaining an irradiation of an optical beam on an optical detecting unit, with which optical intensity is limited in a predetermined area including an optical axis of an optical beam reflected from a target layer, according to the first embodiment;

FIG. 4 is a schematic for explaining an irradiation of an optical beam onto the optical detecting unit, with which the optical intensity is limited in a predetermined area including an optical axis of an optical beam reflected from a non-target layer, according to the first embodiment;

FIG. 5 is a schematic for explaining a distribution of a reflected optical beam projected on the optical detecting unit, according to the first embodiment;

FIG. 6 is a schematic of an optical system in an optical-storage-medium reproducing apparatus according to a second embodiment of the present invention;

FIG. 7 is a schematic for explaining a reflection of a reflected zeroth-order diffracted beam, according to the second embodiment;

FIG. 8 is a schematic for explaining a reflection of reflected first-order diffracted beams, according to the second embodiment;

FIG. 9 is a schematic for explaining how to determine a center portion of a push-pull area, according to the second embodiment;

FIG. 10 is a schematic for explaining how to determine each center portion of two areas, through which the reflected first-order diffracted beams pass, according to the second embodiment;

FIG. 11 is a schematic of an aperture splitting of a polarizing element according to the second embodiment;

FIG. 12 is a schematic of a structure of a light receiving unit and a distribution of a reflected optical beam on the light receiving unit, according to the second embodiment;

FIG. 13 is a schematic of an aperture splitting of a polarizing element according to a third embodiment of the present invention;

FIG. 14 is a schematic of a structure of a light receiving unit and a distribution of a reflected optical beam on the light receiving unit, according to the third embodiment;

FIG. 15 is a schematic of an aperture splitting of a polarizing element according to a fourth embodiment of the present invention; and

FIG. 16 is a schematic of a light receiving unit and a distribution of a reflected optical beam on the light receiving unit, according to the fourth embodiment.

Claims

1. An optical-pickup head device for an optical storage medium that includes a plurality of information-recording layers, comprising: a light source that outputs an optical beam;a condensing unit that condenses the optical beam to a first information-recording layer;an optical detecting unit that detects a reflected optical beam reflected from the optical storage medium; anda limiting element that inputs a first reflected optical beam reflected from the first information-recording layer to the optical detecting unit, and limits or shields an input of a second reflected optical beam reflected from a second information-recording layer to the optical detecting unit.

2. The device according to claim 1, wherein the limiting element diffracts the second optical beam in an area including at least a position through which the second reflected optical beam passes.

3. The device according to claim 1, wherein the limiting element limits optical intensity of the second optical beam in an area including at least a position through which the second reflected optical beam passes.

4. The device according to claim 2, wherein the optical detecting unit includes a first light receiving unit for generating a focus error signal;a second light receiving unit for generating a tracking error signal; anda third light receiving unit for adjusting the tracking error signal, andthe limiting element inputs the first optical beam to the first light receiving unit, the second light receiving unit, and the third light receiving unit, and diffracts the second optical beam to a direction deviated from directions to the first light receiving unit, the second light receiving unit, and the third light receiving unit.

5. The device according to claim 2, wherein the optical detecting unit includes a first light receiving unit for generating a focus error signal; anda second light receiving unit for generating a tracking error signal, andthe limiting element inputs the first optical beam to the first light receiving unit and the second light receiving unit, and diffracts the second optical beam to a direction deviated from directions to the first light receiving unit and to the second light receiving unit.

6. An apparatus for reproducing an optical storage medium that includes a plurality of information-recording layers, comprising: a light source that outputs an optical beam;a condensing unit that condenses the optical beam to a first information-recording layer;an optical detecting unit that detects a reflected optical beam reflected from the optical storage medium; anda limiting element that inputs a first reflected optical beam reflected from the first information-recording layer to the optical detecting unit, and limits or shields an input of a second reflected optical beam reflected from a second information-recording layer to the optical detecting unit.

7. A method of reproducing an optical storage medium that includes a plurality of information-recording layers, comprising: condensing an optical beam output from a light source to a first information-recording layer;detecting including an optical detecting unit detecting a reflected optical beam reflected from the optical storage medium; andlimiting including inputting a first reflected optical beam reflected from the first information-recording layer to the optical detecting unit; andeither one of limiting and shielding an input of a second reflected optical beam reflected from a second information-recording layer to the optical detecting unit.