Dynamic information storage or retrieval – Storage medium structure – Adjuncts or adapters
Reexamination Certificate
1998-05-13
2001-03-06
Ometz, David L. (Department: 2754)
Dynamic information storage or retrieval
Storage medium structure
Adjuncts or adapters
Reexamination Certificate
active
06198718
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a disc cartridge, and more particularly, relates to a disc cartridge which can be applied to an optical disc system. In the optical disc system of the present invention, an embedded member for relieving the shock in the gap between the shutter and the case of the optical disc system is provided. In addition, a sheet-like member is provided for cleaning the surface of an optical disc accommodated in the optical disc system so that the recording and playback characteristics can be effectively prevented from being deteriorated by the effects of dust particles and other foreign materials adhered to the surface of the optical disc.
2. Description of the Prior Art
The DVD (Digital Versatile Disc) has been proposed as an optical disc for use in a conventional optical disc drive for recording information onto the disc at a high recording density. By irradiation of a laser beam with a wavelength of 650 nm by means of an optical system with a numerical aperture of 0.6 upon a DVD, one side of the optical disc can be used for recording data of up to 2.6 MB in length. As a result, one side of the optical disc can be used for recording a video signal having a playback time of about 1 hour.
In such an optical disc drive, the desired data is recorded on and reproduced from an optical disc by adopting a non-contact technique. The optical disc is normally kept in a plastic case for preventing finger prints from being imprinted on the surfaces of the disc and for extended storage of the disc. When using the optical disc, the disc is removed from the plastic case and mounted on the optical disc drive.
Of course, in the case of a video tape recorder for home applications, the basic recording time is 2 hours. In order to allow the user to use an optical disc drive in the same way as the home video tape recorder, it is necessary for the optical disc drive to be capable of recording an even larger amount of data. In addition, in order to allow processing, such as editing to be performed through effective utilization of characteristics of the optical disc including a random access function, it is necessary to increase the recording time of the video signal to a length on the order of 3 hours. In a DVD system having such capabilities, it is necessary for the optical disc to be able to record data of up to about 8 MB.
As a result, it is necessary to record a video signal at a high recording density in the optical disc drive by means of an optical system having a high numerical aperture. As for the optical disc, it is necessary to further reduce the thickness of a light transmissive layer which allows a laser beam to pass therethrough in order to decrease the effect of a skew (bend or warp). However, deterioration of the recording and playback characteristics may result which is caused by dust particles and other foreign particles adhering to the surfaces of the optical disc.
In order to explain the problem described above in more detail, results of an experiment performed by using an optical disc drive having a numerical aperture of 0.8 and a light transmissive layer with a thickness of 0.1 mm are compared with results of an experiment performed by using an optical disc drive having a numerical aperture of 0.6 and a light transmissive layer with a thickness of 0.6 mm. As is shown in
FIG. 25
, if the numerical aperture is increased while the thickness of the light transmissive layer is reduced, even microscopic dust and other foreign particles adhered to the surfaces of the optical disc can cause a burst error. Such dust and other foreign particles continually accumulate on the surfaces of the optical disc. As a result, the recording and playback characteristics of the optical disc drive gradually deteriorate over extended use of the disk drive.
OBJECTS AND SUMMARY OF THE INVENTION
Therefore, it is an object of the present invention to provide a disc cartridge for an optical disc which avoids the aforementioned disadvantages of the prior art.
It is an additional object of the present invention to provide a disc cartridge which can be used for recording data at a higher recording density onto an optical disc accommodated in the disc cartridge in comparison with conventional disc cartridges.
Moreover, it is a further object of the present invention to provide a disc cartridge which is capable of effectively preventing deterioration of the recording and playback characteristics of the optical disc caused by the effects of dust particles and other foreign materials adhered to on the surface of the optical disc.
In order to solve the aforementioned problems, a disc cartridge is provided for accommodating and retaining an optical disc having data recorded onto and reproduced therefrom by irradiation of a laser beam wherein the optical disc can be rotated but cannot be easily removed therefrom. This disc cartridge includes a shock relieving or sealing member which surrounds the entirety or part of an opening formed on the housing of the disc cartridge which allows a laser beam to be irradiated onto the optical disc. This shock relieving or sealing member is also used for closing a gap formed between a shutter and a peripheral member of the opening of the disc cartridge for preventing and/or reducing the amount of dust particles and/or foreign materials entering the opening and being adhered to the optical disk.
In addition, the cartridge disc is also provided with a movement restricting mechanism for retaining the optical disc and limiting movement of the shutter.
Moreover, the disc cartridge also has sheet-like members provided on at least one surface of the optical disc for cleaning the surface of the optical disc so that when the optical disc is rotated in the disc cartridge, foreign materials adhered to the surface of the optical disc are absorbed by the sheet-like member.
Furthermore, the disc cartridge is also provided with pressing members for pressing the sheet-shaped members against the surfaces of the optical disc. The sheet shaped members can each face a surface of the optical disc and are joined with each other to form a single assembly having a shape resembling an envelope for enclosing the optical disc therein. The sheet-shaped members are formed to cover both the surfaces of the optical disc except a portion in close proximity to the rotational center of the optical disc and an area that would otherwise disturb an incident laser beam coming from the opening if covered by the sheet-shaped members.
As described above, an optical disc is accommodated and retained in a disc cartridge of the present invention so that the optical disc can be rotated but cannot be easily removed therefrom. This disc cartridge includes a shock relieving or sealing member which surrounds the entirety or part of an opening formed on a housing of the disc cartridge to allow a laser beam to be irradiated upon the optical disc. This disc cartridge is further used to close a gap between the shutter and the peripheral portion of the opening of the disc cartridge. As a result, the amount of dust particles and other foreign material intruding onto the surfaces of the optical disc can be reduced.
In addition, since the cartridge disc is also provided with a movement restricting mechanism for holding the optical disc and for limiting the movement of the shutter, the shutter can be prevented from being opened and closed carelessly, allowing the amount of dust particles and other foreign materials intruding onto the surfaces of the optical disc to be reduced.
Moreover, the disc cartridge also has sheet-like members provided on at least one surface of the optical disc for cleaning the surfaces of the optical disc so that dust particles and other foreign materials intruding into the inside of the disc cartridge can be prevented from being accumulated on the surfaces of the optical disc.
Furthermore, since the disc cartridge is also provided with pressing members for pressing the sheet-shaped members against the surfaces of the optical dis
Mori Hidenori
Watanabe Toshio
Castro Angel
Frommer William S.
Frommer Lawrence & Haug LLP.
Ometz David L.
Ryan Matthew K.
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