Matsushita Electric Industrial Co., Ltd.

Panasonic Corporation

Panasonic Intellectual Property Management Co., Ltd.

Matushita Electric Industrial Co., Ltd.

Akihiro Sakaguchi

Masatoshi Yajima

Hiroyuki Yamaguchi

Kenji Nagashima

Shinichi Yamada

Masanari Mohri

Yasushi Kobayashi

Masaya Kuwahara

Masuo Maruyama

Masayoshi Shioya

Yasuo Nishihara

Youichi Saitou

Hiroshi Gotou

Tsuyoshi Ogomori

A document classification method includes extracting one or more first feature words from first sentence information included in a first document to be classified, extracting, from a database including a plurality of cases, a predetermined number of first cases similar to the first document in accordance with the one or more first feature words extracted from the first sentence information, the plurality of cases including the predetermined number of first cases and being classified in advance into the at least one category, the plurality of cases each including second sentence information indicating a main point of each of one or more items, the one or more items being classified in advance depending on meaning of the item, extracting one or more second feature words of each of the predetermined number of first cases from the second sentence information of each of the predetermined number of first cases, calculating a degree of coincidence between each of the predetermined number of first cases and the first document based on the one or more second feature words extracted from the second sentence information of the first case, and classifying the first document into a category among the at least one category, the category being a category into which a first case having a highest degree of coincidence among the predetermined number of the first cases is classified.

Document classification method, document classifier, and recording medium

A light intensity control device of the present invention includes a light source for outputting a plurality of types of light beams having different wavelengths; a light receiving section for receiving and converting the light beams into an electric signal in accordance with the intensity of the respective light beam; and a polarization separation section provided between the light source and the light receiving section. The plurality of types of light beams include a first light beam and a second light beam having a longer wavelength than that of the first light beam. The polarization separation section guides both a first polarization direction light component of the second light beam and a second polarization direction light component, perpendicular to the first polarization direction, of the second light beam to the light receiving section. The polarization separation section guides a first polarization direction light component of the first light beam to the light receiving section, and suppresses a second polarization direction component, perpendicular to the first polarization direction, of the first light beam from advancing to the light receiving section.

Light intensity controller and optical pickup device

An optical information read/write apparatus according to the present invention includes: a light sourcethat emits a laser beam to access an information storage medium optically; a laser driverfor supplying drive current to a semiconductor laser as the light sourcean RE superimposed current generatorfor adding RE superimposed current to the drive current; a temperature sensorfor detecting a temperature around the light sourceand a control section for switching the values of the RE superimposed current according to the temperature detected.

Optical disk drive with temperature based control of RF superimposed current

Optical disks compliant with different standards are recorded or reproduced by a single recording/reproducing apparatus by a first step of determining a substrate thickness of the disk based on a focusing error signal, when a focusing section for bringing the light beam into a focus on the disk is moved in such a way as to approach or withdraw from the recording surface of the disk; a second step of performing any one step of determining the number of recording surfaces of the disk when the focusing section is moved in such a way as to approach or withdraw from the recording surface of the disk, and determining whether or not the disk can be recorded and reproduced using a tracking error signal detected when the light beam crosses the track.

Disk type determination method

An optical head device of the present invention includes: a semiconductor laser for emitting a light beam; a first optical element for converting the light beam emitted from the semiconductor laser into collimated light having an elliptic beam shape; shaping means for shaping the beam shape of the collimated light from an ellipse to a circle; and a second optical element for directing the collimated light having the beam shape which has been shaped into a circle onto an optical information recording medium. The semiconductor laser is located so that a short axis direction of the ellipse is substantially parallel to a rotation axis direction of the optical information recording medium.

Beam expander to change an elliptical light beam emitted from a laser

A lens actuator for use in an optical data reader, comprising: a base on which a plurality of N (N=natural number not less than two) objective lenses corresponding to N optical data recording media having substrates of different thicknesses, respectively are mounted; a supporting shaft which is provided on the base such that the base is movable vertically and rotatable within predetermined ranges, respectively relative to the supporting shaft; a pair of driving coils for performing changeover among the objective lenses and tracking follow-up of the data recording media; and N pairs of magnets which form a magnetic circuit together with the driving coils such that the base is rotated by the driving coils and the magnets.

Lens actuator for dual lens optical disk apparatus having lens mounting

Growing community of inventors

Osaka, Japan

Akihiro Sakaguchi