Dynamic information storage or retrieval – Specific detail of information handling portion of system – Radiation beam modification of or by storage medium
Reexamination Certificate
2000-12-13
2003-05-06
Huber, Paul W. (Department: 2653)
Dynamic information storage or retrieval
Specific detail of information handling portion of system
Radiation beam modification of or by storage medium
C369S118000
Reexamination Certificate
active
06560189
ABSTRACT:
BACKGROUND OF THE INVENTION
i) Field of the Invention
The present invention relates to an optical information storage apparatus for irradiating a predetermined optical information storage medium with light to access the medium, and an optical device for use in the optical information storage apparatus.
ii) Description of Related Art
An optical disk has been heretofore used as an optical information storage medium for recording/reproducing information such as voice, letter, and image in CD, CD-ROM, CD-R, DVD, PD, MO, MD, and the like. In the optical disk, the information is generally recorded in a band-like area surrounded with a concentric or spiral guide groove (track). Moreover, as an optical information storage apparatus for moving a condensing spot along the track of the optical information storage medium to access the information, apparatuses of various modes such as an installed type, car mounted type, and portable type have been developed. Particularly, MD is popular mainly among young people, and the sales of very compact portable apparatuses with sizes close to an optical disk jacket size are on the increase. Furthermore, as an exterior storage apparatus to be attached to a mobile personal computer (PC) or the like, development of the compact optical information storage apparatus has been expected.
In general, the optical information storage apparatus is provided with an optical head for forming a light spot on the optical disk track to access the information. Moreover, in order to develop the aforementioned compact optical information storage apparatus, an optical head has intensely been developed in which a laser diode (LD) as a light source, a beam splitter (BS), a photo detector for monitoring light outputs, an optical component and photo detector for detecting servo or RF signal, and further a preamplifier circuit are unified and integrated, and an optical device unified with the optical component of the optical head has also been intensely developed.
However, in such unified and integrated optical head, it is expected that noise attributed to fluctuation of the condensing spot during movement of the condensing spot along the track, or noise attributed to wobbling for indicating an information address or the like by meander of the track is generated. Therefore, it is desired that a compact optical information storage apparatus be realized by maintaining unity of the optical head and reducing the noise mixed in a reproducion signal.
SUMMARY OF THE INVENTION
The present invention has been developed in consideration of the aforementioned situations, and an object thereof is to provide a compact optical information storage apparatus in which a signal quality is high, reliability of signal reproduction is also high, and high-density recording is possible, and to provide a unified optical device for use in the optical information storage apparatus.
To achieve the object, according to the present invention, there is provided a first optical information storage apparatus comprising: a light source for emitting a light; an objective optical system for concentrating the light emitted from the light source to an optical information storage medium which generates a return light partially including a signal light in accordance with stored information, and for directing the return light from the optical information storage medium to a light source side; and an optical device, positioned between the light source and the objective optical system, for guiding the light emitted from the light source to the objective optical system, and separating the signal light from the return light reflected by the optical information storage medium and returned via the objective optical system.
The optical device comprises: a separation surface for transmitting the light emitted from the light source to the objective optical system, and reflecting the signal light to separate the signal light from the return light; and a reflective surface including a main portion for reflecting the signal light reflected by the separation surface in a predetermined direction, and a mask portion provided with an optical property different from the optical property of the main portion.
In the first optical information storage apparatus of the present invention, the mask portion may absorb the light, the mask portion may transmit the light, the mask portion may reflect the light in a direction different from the direction of reflection by the main portion, or the mask portion may reflect the light in the same direction as the direction of the reflection by the main portion, and generate a phase difference different from the phase difference of the light generated during the reflection by the main portion.
Moreover, in the first optical information storage apparatus of the present invention, the mask portion is preferably provided with the optical property in accordance with a polarization direction.
Furthermore, in the first optical information storage apparatus of the present invention, the mask portion preferably has a band shape which is longitudinal in a direction corresponding to a width direction of the track formed in the optical information storage medium, and more preferably the mask portion is formed in two places apart from each other in the direction corresponding to the width direction of the track formed in the optical information storage medium.
Since the first optical information storage apparatus of the present invention is provided with the aforementioned mask portion, noise is reduced by a first principle described later. Moreover, since the optical device is provided with the reflective surface including the mask portion, it is easy to manufacture or design the aforementioned unified optical device, and the first optical information storage apparatus of the present invention can be realized as a compact apparatus.
When the mask portion absorbs the light, for the first optical information storage apparatus of the present invention, the reflective surface comprises the surface of the optical device, on which the signal light is incident from the inside of the optical device, and the mask portion is preferably constituted by attaching a light absorbing material to the outside of the optical device with respect to a predetermined portion of the reflective surface.
As the mask portion constituted by attaching the light absorbing material in this manner, a light absorbing pigment may be applied, or a tape-like light absorbing material may be bonded.
It is easy to produce the mask portion constituted by attaching the light absorbing material, which can reduce costs of the optical device and optical information storage apparatus.
Moreover, when the mask portion is formed by attaching the light absorbing material, the reflective surface preferably satisfies a total reflection condition.
When the reflective surface satisfies the total reflection condition, a light absorption effect by the light absorbing material is remarkable, and the reflective surface is particularly effective for noise reduction.
Moreover, when the mask portion transmits or reflects the light, in the first optical information storage apparatus of the present invention, the reflective surface comprises the surface of the optical device, on which the signal light is incident from the inside of the optical device, and the mask portion preferably comprises a concave portion or a convex portion disposed on the predetermined portion of the reflective surface.
The mask portion comprising the concave portion or the convex portion can easily be formed by glass molding, which can reduce the costs of the optical device and optical information storage apparatus.
Furthermore, when the mask portion generates a phase difference different from the phase difference of the light generated during reflection in the main portion, in the first optical information storage apparatus of the present invention, the reflective surface comprises the surface of the optical device, on which the signal light is incident from the inside of the optical device, and
Aoyama Nobuhide
Hasegawa Shin-ya
Fujitsu Limited
Greer Burns & Crain Ltd.
Huber Paul W.
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