Panasonic Corporation

Matsushita Electric Industrial Co., Ltd.

Panasonic Intellectual Property Management Co., Ltd.

Hiroaki Matsumiya

Kazuo Momoo

Yuichi Takahashi

Seiji Nishiwaki

Kenji Nagashima

Junichi Asada

Youichi Saitoh

Jun-ichi Asada

Hiroshi Kayama

An optical pickup includes a light source; a diffraction elementfor generating a write main beam and a read sub-beam via diffraction; an objective lens; a wavelength plate; a polarization hologram elementhaving a plurality of diffraction regions with different diffraction characteristics, designed so that each diffraction region separates a light beam reflected from the optical storage medium and transmitted through the wavelength plate into a 0order light beam and &#xb1;1order light beams; an actuator; and a photodetectorconfigured to detect a light beam reflected from the optical storage mediumand diffracted by the polarization hologram element. The photodetectorgenerates an RF signal from a detection result concerning a 0order light beam derived from the main beam, generates a focus error signal and a tracking error signal from a detection result concerning one of &#xb1;1order light beams derived from the main beam, and generates a signal indicating that data has been recorded normally from a detection result concerning a 0order light beam derived from the sub-beam.

Optical pickup and optical recording and reproducing device

An exemplary optical pickup comprises: a light source with first and second emission points; an optical branching element which branches light emitted from the first emission point into multiple light beams including a first main beam and first sub-beams and which also branches light emitted from the second emission point into multiple light beams including a second main beam and second sub-beams; an optical system which condenses the multiple light beams produced by the optical branching element onto an optical storage medium, thereby making the first and second main beams form a write light beam spot and a read light beam spot, respectively, on a target recording track on the storage medium and making the first and second sub-beams form reference light beam spots and other light beam spots somewhere on the storage medium other than the target recording track.

Optical pickup and optical read/write apparatus

When performing recording/reproduction of information for a given recording layer of an optical disc having three recording layers, influences of reflected light from other recording layers are reduced or removed, thus making it possible to obtain a more stable RF signal or focus error signal. An optical pickup device includes a light source, a collimator lens, an objective lens, a photodetector, and a light shielding member. Among the recording layers of the optical disc, a first layer and a second layer adjoining each other are disposed in the order of the first layer and second layer from near the objective lens. The light shielding member is disposed at a position satisfying the condition d&#x3e;dto block a part of reflected light from the second layer when light is converged on the first layer, where d is an optical path length from the photodetector to the light shielding member; and dis a distance from the photodetector to a position at which reflected light from the second layer becomes focused between the collimator lens and the photodetector.

Optical pickup device and optical disc device

A focus error signal is generated by a first-order diffracted light diffracted by regionson a hologram plane, and an offset of a tracking error signal is canceled by first-order diffracted light diffracted by regionson the hologram plane. Consequently, even when there is an error in the substrate thicknesses of optical discs, jitter of a reproduction signal at a focus control point can be reduced by decreasing the distance between the focus control point and the point where the jitter is minimized.

Optical disc device

When recording on and/or reproducing from an information recording medium having a plurality of recording layers is performed, there has been a problem in appropriately detecting a control signal at the time of the recording and/or reproducing, since reflected light from a recording layer, which does not undergo the recording and/or reproducing, enters a photodetector concurrently with reflected light from a recording layer which undergoes the recording and/or reproducing. In the present invention, a polarization hologram is used to diffract light outputted from a light source and to generate a main beam, which is a zeroth-order light beam, and a pair of sub beams, which is a positive first-order light beam and a negative first-order light beam each having a polarization direction perpendicular to a polarization direction of the main beam. Accordingly, it is possible to prevent the reflected sub beams from a recording layer, which is a target undergoing recording and/or reproducing, from interfering with the reflected main beam from a recording layer, which is a non-target not undergoing the recording and/or reproducing. Therefore, it is possible to obtain an accurate control signal based on the sub beams, and also possible to realize an optical pickup device having a preferable recording performance.

An optical disk apparatus according to the present invention includes: a rotation driving section on which an optical disk is to be mounted and which drives the optical disk so as to be rotated; a light source; an objective lens for converging light from the light source onto an optical disk mounted on the rotation driving section; a photodetector having at least two detection sections for detecting reflected light, from the optical disk, of the light; and an error signal generation section for deriving a difference signal and a sum signal of respective outputs from the two detection sections of the photodetector, adjusting an offset in at least the sum signal among the difference signal and the sum signal, and thereafter dividing the difference signal by the sum signal whose offset has been adjusted to generate a position error signal of the objective lens.

Optical disk apparatus

An optical pickup device capable of correcting an off-tracking which is ascribable to a phase shift of a differential push-pull signal waveform, even when an optical disk or an objective lens is tilted along a radial direction of the optical disk, so that stable tracking control can be performed; and, an optical disk apparatus comprising such an optical pickup device.

Optical disk apparatus with phase difference offset

To implement light quantity monitoring with high frequency responsivity and correction of astigmatic differences of a semiconductor laser with a simple configuration with a fewer parts. Of the light beam output from a semiconductor laser light source, a peripheral beam component is entered by a light reflection elementinto an anterior light monitoring photodetectorformed in the vicinity of a semiconductor laser light source. Furthermore, the surface of the reflection sphere of the light reflection element is formed anamorphic, and thus condensed to an appropriate size on the photodetector without being focused, providing high frequency responsivity. Furthermore, the light reflection elementis placed inclined at a predetermined angle so as to cancel out astigmatic difference of the optical semiconductor laser light source. In addition, the photodetectoris placed in the direction so that a reflected lightis bent by an inclination of the light reflection element, reducing the amount of parallel displacement during adjustment of the light reflection element

Optical head apparatus

Optical device for recording and reproducing information

To implement light quantity monitoring with high frequency responsivity and correction of astigmatic differences of a semiconductor laser with a simple configuration with fewer parts. Of the output from a semiconductor laser light source, a peripheral component is entered by a light reflection element into an anterior light monitoring photodetector formed in the vicinity of a semiconductor laser light source. Furthermore, the surface of the reflection sphere of the light reflection element is anamorphic, and thus condensed to an appropriate size on the photodetector without being focused, providing high frequency responsivity. Furthermore, the light reflection element is inclined at a predetermined angle to cancel out astigmatic differences of the optical semiconductor laser light source. In addition, the photodetector is placed so that reflected light is bent by an inclination of the light reflection element, reducing the amount of parallel displacement during adjustment of the light reflection element.

Growing community of inventors

Osaka, Japan

Hiroaki Matsumiya