Dynamic information storage or retrieval – With stylus cleaning or treatment
Reexamination Certificate
1995-03-17
2001-11-13
Miller, Brian E. (Department: 2652)
Dynamic information storage or retrieval
With stylus cleaning or treatment
Reexamination Certificate
active
06317401
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to optical disk apparatuses used with replaceable optical disks each accommodated in a cartridge and, more particularly, to an optical disk apparatus, in which an optical head objective lens is cleaned using a cleaning disk.
In a usual optical disk apparatus, information is recorded by projecting a beam from a laser diode onto a rotating optical disk. The recorded information is reproduced through detection of changes in the intensity of the reflected beam from the optical disk, polarization surface and other characters. Such optical disk apparatus provides for high information recording density, and thus its applications to external memories of information processing systems are expected.
Normally, a laser beam emitted from the laser diode is focused by an objective lens provided on an optical head mounted on a carriage onto the optical disk. The reflected beam from the optical disk is also focused by the objective lens to be incident on a light-receiving element for conversion to an electric signal. The objective lens is driven for focus control by a lens actuator in the optical axis directions. Further, the carriage carrying the optical head is by a voice coil motor in radial directions of the disk for position control of the optical head to a desired position. The objective lens is found close to the disk surface, typically several millimeters apart. Therefore, its surface is readily contaminated by winds produced by the rotation of the optical disk. Contamination of the objective lens surface results in reduction of the laser beam intensity, scattering of the beam and disturbance of the laser beam intensity distribution, thus having significant adverse effects on the write performance, the read performance and further the servo performance such as focus servo and track servo. A method of cleaning the objective lens surface uses a cleaning disk. With the cleaning disk, the cartridge case and disk resemble those of the normal optical disk cartridge. A difference is that the cleaning disk has a brush provided on part of its surface. The cartridge accommodating the cleaning disk, like the normal optical disk cartridge, is loaded in the apparatus, and the disk is rotated, whereby the objective lens surface is cleaned by the brush on the disk.
However, in the cleaning of the objective lens with such a cleaning disk, the objective lens is held stationary, and its surface is rubbed by the brush of the rotating disk. This means that only part of the brush can be used for the cleaning. Therefore, the brush is liable to be deformed, and also it is contaminated only locally. Further, the rotating brush touches the stationary objective lens in a fixed fashion, and therefore the lens can not be perfectly cleaned.
Meanwhile, when writing data in the optical disk, the desired track is first erased by projecting a laser beam thereonto in the presence of an external magnetic field applied in the erase direction. Then, data is written by projecting a data-modulated laser beam in the presence of an external magnetic field applied in the write direction. Further, a verify read is done to confirm the written content. Therefore, with an optical head which projects a single laser beam, the optical disk has to be rotated by at least three rotations in the write operation. To permit this write operation at an increased speed, there is provided an optical disk apparatus, which has three exclusive laser diodes for erasing, writing and reading, and in which two objective lenses, one for erasing and the other for writing and reading, are mounted together with respective lens actuators on the optical head. With such a two-actuator structure optical disk apparatus, the erase, write and read operations can be performed during one rotation of the disk, and thus the write operation speed can be increased by three times compared to the case of the ordinary optical disk apparatus. However, in such a two-actuator optical disk apparatus the two lens actuators are disposed in the same radial position of the disk and considerably close to the disk in the circumferential direction thereof. Therefore, the cleaning of the succeeding objective lens with the cleaning disk with the brush is obstructed by the preceding one. Therefore, unlike the single-lens structure, the lenses can be cleaned only insufficiently.
SUMMARY OF THE INVENTION
The invention seeks to provide an optical disk apparatus, which permits sufficient cleaning of objective lenses.
According to the invention, when cleaning the surface of an objective lens provided on an optical head by causing rotation of a cleaning disk with a brush, a lens actuator is driven to move the lens toward and away from the cleaning disk simultaneously with the rotation thereof. Alternatively, the cleaning control may be such as to cause reciprocations of a carriage carrying the optical head toward the inner and outer peripheries of the cleaning disk simultaneously with the rotation thereof. Further, the operation of reciprocating the carriage carrying the optical head toward the inner and outer disk peripheries and the operation of moving the objective lens toward and away from the cleaning disk with a lens actuator may be performed in combination. As a further alternative of the cleaning control, the cleaning disk may be rotated alternately in the normal and reverse directions.
With an optical head having a two-actuator structure, simultaneously with moving one objective lens toward the disk surface with one lens actuator, the other objective lens is moved away from the disk surface with the other lens actuator, and vice versa, these operations being performed alternately.
The cleaning operation is performed after the cartridge accommodating a cleaning optical disk has been inserted in the apparatus and loaded on a spindle motor, and it is started in response to the issuance of a cleaning command from an upper order system. Further, the cleaning cartridge case may be provided with a peculiar physical shape, for instance recesses or holes, indicative of that the cartridge is for cleaning, and the cleaning operation may be started automatically when it is determined from the physical shape that the loaded cartridge is for cleaning. As the physical shape indicative of the cleaning cartridge, it is desirable to utilize media sensor holes provided on the case surface at specific positions thereof.
With such optical disk apparatus according to the invention, the objective lens surface can be cleaned sufficiently by repeatedly moving the objective lens with the lens actuator or actuators in the focus direction repeatedly to to bring the lens or lenses toward and away from the brush on the cleaning disk while causing rotation thereof. Further, by causing the optical head carried on the carriage in the radial directions of the disk with a head actuator, the entire brush can touch the objective lens or lenses to clean the same, that is, the entire brush can be used for the cleaning, and this eliminates or reduces local deformation or contamination of the brush. Further, in the case of the two-actuator structure, by alternately moving the two objective lenses in the focus direction with the two actuators, each lens can be cleaned without being obstructed by the preceding lens. Thus, the two objective lenses can be sufficiently cleaned.
The above and other objects, features and advantages of the present invention will become more fully apparent from the following detailed description with when the same is read with reference to the accompanying drawings.
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patent: 2-29940 (1990-01-01), None
patent: 2-29939 (1990-01-01
Masaki Takashi
Yanagi Shigenori
Fujitsu Limited
Greer Burns & Crain Ltd.
Miller Brian E.
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