Dynamic information storage or retrieval – With servo positioning of transducer assembly over track... – Optical servo system
Reexamination Certificate
1999-02-08
2001-09-18
Huber, Paul W. (Department: 2651)
Dynamic information storage or retrieval
With servo positioning of transducer assembly over track...
Optical servo system
C369S044320, C369S053280
Reexamination Certificate
active
06292444
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical storage device, or more particularly, to an optical storage device in which electrical means are substituted for the capabilities of sensors that cannot be stowed in the optical storage device when the optical storage device is made thinner.
2. Description of the Related Art
In existing storage media, a compact cassette for recording sound which utilizes magnetic tape, a video cassette for recording pictures, and the like, are known. However, data recorded on any of these media is not accessible at random. Besides, the recorded data is analog information. There are therefore such drawbacks that reproduced data may contain noise, that the data may be deteriorated when copied, that the data may be deteriorated when stored for a prolonged period of time, and the like.
As for another kind of storage medium, an optical disk making it possible to record a digital signal, into which data is converted, in a data track on a disk, and to read the signal using returned light of a laser beam irradiated to the data track has been put to practical use. Examples typical of the optical disk are a compact disk (CD) for recording music, a laser disk (LD) for recording pictures, and the like. Moreover, development of a digital video disk (DVD) that is compactly designed for recording pictures is in progress. In addition, since these kinds of optical disks have large storage capacities, they have come to be used as data storage media by the names of a CD-ROM, LD-ROM, and the like.
In recent years, a magneto-optical disk making it possible to record data on a recording medium using a laser beam and magnetism, and to read the data using the laser beam has also been put to practical use. Since this kind of magneto-optical disk has a large storage capacity, it is used as an optical storage device in the form of an external memory for a computer.
As mentioned above, storage media using light include an optical disk and a magneto-optical disk. Herein, a description will proceed on the assumption that any storage media using light are regarded generally as optical disks.
The optical disk used for an optical storage device is popular as a storage medium having a pivotal stance in the multimedia systems that have appeared in recent years, and is normally stowed in a cartridge to ensure portability. The optical disk cartridge is loaded in an optical disk unit. Information is then written to or read from the optical disk by means of an optical head.
Currently, the optical disk unit often used externally is connected to a computer via a SCSI interface.
Recently, it has become desirable to mount an optical disk unit in a portable personal computer. Technological development is under way at a quick pace in an effort to realize a more compact and lightweight design. Taking, for instance, a floppy disk unit and hard disk unit which have been used as an external storage for a personal computer in the past, the trend toward a more compact design has progressed so greatly that a floppy disk unit or a hard disk unit can be mounted in a slot in a main unit of a personal computer which is approximately 17 mm thick.
For inserting the optical disk unit that is an optical storage device into the slot of approximately 17 mm thick and designed for a floppy disk unit or hard disk unit, the existing optical disk unit must be made thinner.
However, when the optical disk unit is made thinner so that it can be inserted into the slot of approximately 17 mm thick designed for a floppy disk unit or hard disk unit and formed on a personal computer, since a space inside the optical disk unit is restricted vertically, a conventional position sensor and a sensor for detecting the position of an objective lens must be made smaller. Because the size of the position sensor and the sensor for detecting the position of an objective lens make it hard to position a carriage having an optical head mounted thereon inside the optical disk unit.
SUMMARY OF THE INVENTION
The first object of the present invention is to provide an optical storage device that, even when made thinner and deprived of a position sensor, can detect the position of a carriage using a signal read from an optical disk medium.
Moreover, the second object of the present invention is to provide an optical storage device that even when made thinner and deprived of a position sensor, can position a carriage in a laser output adjustment area defined on an optical disk medium.
Furthermore, the third object of the present invention is to provide an optical storage device that even when made thinner and deprived of a position sensor, can position an actuator for an objective lens, which is mounted on a carriage, in the center of the carriage.
In an optical storage device according to the first aspect of the present invention for accomplishing the first object of the present invention, immediately after an optical storage medium is loaded in a main unit, a cutoff frequency change means temporarily sets the cutoff frequency of a filter means, which is located on a path of a signal reproduced via a carriage, to a normally-unused lower frequency. A sector spacing detection means detects a spacing of sectors of the optical storage medium using a signal sent from the filter means. The optical storage device further includes a position information memory means for storing positions in a radial direction of an optical storage medium, and frequencies and sector spacings associated with the positions. Based on the detected sector spacing and data stored in the position information memory means, a track position detection means detects the type of the optical storage medium and the position of a current reproduction track.
According to the first aspect, even if such a situation develops that a conventional position sensor and a sensor for detecting the position of an objective lens must be excluded because an optical disk unit is made thinner, the position of the carriage can be detected using a signal read from an optical disk medium. Consequently, the carriage can be positioned.
In an optical storage device according to the second aspect of the present invention for accomplishing the second object of the present invention, an interception means juts out from part of a carriage in a direction parallel to a movement direction of the carriage. Located across a movement trajectory of the interception means is a photosensor means having the incident light thereof intercepted by the interception means only during a period during which the carriage lies in a laser output adjustment area defined in the vicinity of an outer circumference of an optical storage medium. Driving currents are used to drive the carriage when light incident to the photosensor means intercepted and not intercepted by the interception means are detected and used to compute a holding current for the carriage. Thus, the carriage is held in the laser output adjustment area.
According to the second aspect, even when the optical disk unit is made thinner and deprived of a conventional position sensor, the position of the carriage can be retained in the laser output adjustment area for a laser diode which is defined on an outer circumference of an optical disk medium.
In an optical storage device according to the third aspect of the present invention for accomplishing the third object of the present invention, when a seek operation of a carriage relative to an optical storage medium is started, the carriage can be accelerated smoothly, decelerated smoothly, and thus positioned on a target track. The vibration of a lens actuator on the carriage occurring during seek is minimized, and the lens actuator is locked substantially in the center of the carriage.
According to the third aspect, even when the optical disk unit is made thinner and deprived of a conventional lens position sensor, an objective lens of the lens actuator mounted on the carriage can be positioned in the center of the carriage during seek by controlling a driving spee
Arai Shigeru
Ikeda Toru
Isato Nobuhiko
Minami Akira
Sasaki Masateru
Fujitsu Limited
Greer Burns & Crain
Huber Paul W.
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