Matsushita Electric Industrial Co., Ltd.

Masayoshi Shioya

Hiroyuki Yamaguchi

Mitsuro Moriya

Yasumori Hino

Katsuya Watanabe

Takashi Kishimoto

Yoshihiro Mushika

Shinichi Yamada

Masanari Mohri

Rie Takahashi

Masaya Kuwahara

Masuo Maruyama

Toru Kawabata

Akihiro Sakaguchi

Yasuo Nishihara

Kazumasa Hirano

Shohei Yumita

A method for recognizing at least two types of optical discs, which are associated with multiple different numerical apertures, includes the step of setting the numerical aperture of a focusing mechanism equal to a first one of the multiple different numerical apertures. The focusing mechanism is used to focus a light beam on a data storage layer of a given optical disc. The first numerical aperture is smaller than any of the other numerical apertures. The method further includes the step of recognizing the type of the given optical disc by the first numerical aperture that has been selected in the step of setting the numerical aperture.

Method and apparatus for recognizing optical discs, optical disc drive, and method and apparatus for distinguishing data storage layer

An information recording medium for reproducing information by irradiation with a laser beam condensed by an objective lens with a numerical aperture NA includes a disk-shaped substrate and a recording layer disposed on the substrate. On the surface of the substrate, a plurality of prepit regions and a plurality of data regions are disposed alternately along spiral or concentric virtual track centers. Each prepit region includes a pair of wobble pits for tracking servo, and a length L (&#x3bc;m) of the wobble pit along the virtual track center, a wavelength &#x3bb; (&#x3bc;m) of the laser beam, and a numerical aperture NA satisfy a relationship: 0.3&#x2266;L. NA/&#x3bb;&#x2266;0.65.

Optical recording medium with prepit regions and recording/reproducing method thereof

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

According to a control device for a stepping motor of the present invention, in a first operation mode, a microstep driving section,is selected, and an output of this microstep driving section,is applied to a driving section,through a command selector,, whereby a stepping motor,is microstep driven by this driving section,. Furthermore, in a second operation mode, a forced driving section,is selected, and an output of this forced driving section,is applied to the driving section,through the command selector,, whereby the stepping motor,is forced driven by this driving section,, i.e., a high-speed rotation of a rotor,is started from any rotation angle with the microstep driving. Furthermore, in a third operation mode, a driving pattern generating section,is selected, an output of this driving pattern generating section,is applied to the driving section,through the command selector,, whereby a high-speed rotation driving of the stepping motor,is continued by this driving section

Stepping motor control device and optical head drive device

In an apparatus in which information is reproduced by projecting/receiving an optical beam to/from a recording carrier having a large number of information tracks, tracking control is performed so as to maintain a reproducing position on an information track by supplying a track deviation signal to an actuator. If this track deviation signal becomes asymmetric by an inclination, etc. of the recording carrier so that a shock is applied to the apparatus, jumping out of a track occurs, resulting in slip-off of the optical beam from the reproducing position. This slip-off can be prevented by detecting a position of a movable support member carrying a focusing lens for projecting and receiving the optical beam and feeding back the position signal to the tracking control system, or by extracting a low-frequency component of an output signal of a control circuit and feeding back the extracted signal to the tracking control system.

Slip-off preventing tracking control apparatus

In an apparatus in which information is reproduced by projecting/receiving an optical beam to/from a recording carrier having a large number of information tracks, tracking control is performed so as to keep a reproducing position on an information track by supplying a track deviation signal to an actuator. If this track deviation signal becomes asymetric by an inclination, etc. of the recording carrier so that a shock is applied to the apparatus, jumping out of a track occurs, resulting in slipping-off of the reproducing position. This slipping-off can be prevented by detecting a position of a movable support member carrying a focusing lens for projecting and receiving the optical beam and feeding back the position signal to the tracking control system, or by extracting a low-frequency component of an output signal of a control circuit and feeding back the extracted signal to the tracking control system.

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Itami, Japan

Masayoshi Shioya