Dynamic optical information storage or retrieval – Optical storage medium structure – Disk cartridge
Reexamination Certificate
2002-03-15
2004-11-16
Chen, Tianjie (Department: 2652)
Dynamic optical information storage or retrieval
Optical storage medium structure
Disk cartridge
Reexamination Certificate
active
06820275
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a disc cartridge which rotatably accommodates a disc-shaped disc medium used as a recording/playback medium of an information processing device or the like, and which prevents entry of dust or the like.
2. Description of the Related Art
A disc-shaped disc medium, such as an optical disc, a magneto-optical disc, or the like, is used, for example, as a portable recording/playback medium for a computer. When recording or playback of the disc medium is carried out, laser beam is illuminated onto the recording surface while the disc medium is rotated in a state of being loaded in a drive device. In this way, recording of information is carried out by pit formation or phase changes or magnetization or the like due to decomposition of the dye layers of the recording surface, or recorded information is played back on the basis of differences in the reflectivity or the polarizing angle of the laser beam.
Accordingly, there are disc media in which, when information is recorded on such a disc medium, it can be visually confirmed to what point recording has been carried out. Namely, the regions at which information is recorded/unrecorded can be judged due to the hue of the recording surface of the disc medium changing.
Further, in such disc media, shortening of the wavelength of the laser beam which is illuminated onto the recording surface has been proposed in order to increase the recording capacity. When recording or playback of information is carried out by using this short-wavelength laser beam (e.g., a blue-violet color laser), in order to suppress the attenuation of the laser beam due to the cover layer which protects the recording surface of the disc medium, the cover layer must be made thin. By making the cover layer thin in this way, the diameter of the laser beam at the surface of the cover layer (the surface which is exposed to the exterior) decreases, and it is not possible to ignore the effects of dust and the like adhering to the surface of the cover layer.
Thus, disc cartridges, which accommodate a disc medium in a case and prevent adhesion of dust or the like onto the disc medium, are employed. Such a disc cartridge is formed to include an opening, which is for exposing to the exterior a center hole portion (center core portion) provided at the central portion of the disc medium and a portion of the recording surface (the cover layer), and a shutter member which opens and closes this opening.
In this way, in the disc cartridge, by closing the opening by the shutter member when the disc medium is not in use, entry of dust or the like into the disc cartridge, i.e., adhesion of dust or the like onto the disc medium, is prevented. At the time when the disc medium is used, by opening the opening as the disc cartridge is loaded into the drive device, the center hole portion (the center core portion) can be held by a rotation spindle shaft, and the laser head can approach the recording surface (laser beam can be illuminated).
However, in such a disc cartridge, even if the disc medium is such that information recorded/unrecorded regions can be visually judged by a change in the hue of the recording layer, because the disc medium is housed in a case, if the disc cartridge is not loaded into a drive device, it is not possible to recognize the correct unrecorded amount. Thus, it is inconvenient for the user of the disc cartridge, and the ability to easily visually recognize the approximate unrecorded amount of the disc medium has been desired in the conventional art.
Further, in such a disc cartridge, in the aforementioned state in which the opening is open, there is the need to ensure a space for accommodating the shutter member, and a problem arises in that it is difficult to make the disc cartridge compact. Thus, to aim for compactness, a disc cartridge in which the shutter member is divided in two has been disclosed in Japanese Patent Application Laid-Open (JP-A) No. 2000-30394 and the like. In the disc cartridge of JP-A 2000-30394, the entire opening is closed in a state in which the end surfaces of a first shutter member, which mainly closes the opening portion for laser head insertion (approach), and a second shutter member, which mainly closes the opening portion for insertion of the rotation spindle shaft, abut one another.
When this disc cartridge (disc medium) is to be used, it is loaded (inserted) into a drive device. Along with this loading, a lock releasing lever, which is disposed within an arm guide groove, is operated, and a moving operation portion, which is connected to the first shutter member, is moved along the arm guide groove. In this way, the first shutter member is rotated in the direction of opening the opening while a circular-arc-shaped guide portion of the first shutter member slides along a tubular inner wall provided at a case.
Further, along with this rotation, the second shutter member is pressed by a convex portion of the first shutter member which abuts an engagement portion of the second shutter member. The second shutter member rotates in a direction of opening the opening, which is different than that of the first shutter member. In this way, the first shutter member and the second shutter member are accommodated within accommodating spaces which substantially correspond to the projection surface area of the disc-shaped disc medium. Thus, this disc cartridge aims for a reduction in size and a reduction in thickness, while preventing adhesion of dust and the like onto the disc medium.
With such a conventional disc cartridge, at the time of closing the opening which has been opened, due to the urging force of a torsion spring which urges the second shutter member in the closing direction, not only is the second shutter member rotated, but also, the first shutter member, whose sliding resistance accompanying rotation (mainly, the sliding resistance between the guide portion and the inner wall) is large, is also rotated. Thus, there are cases in which the operations of the first shutter member and the second shutter member are not carried out smoothly. Further, in order to make these operations smooth, excessive machining precision and assembly precision are required at each portion, which is a cause of high costs.
Moreover, in order to rotate the first shutter member as well, the spring constant of the torsion spring must be made large, and a problem arises in that the handling of the torsion spring is complex and the assemblability thereof is poor. In particular, because the torsion spring is disposed in a vicinity of the rotation shaft of the second shutter member, the spring constant must be made even greater. This problem becomes marked, and the torsion spring itself must be made larger. A problem arises in that either the entire disc cartridge becomes larger sized, or the regions of operation of the respective shutter members become smaller (i.e., the opening becomes smaller and cannot handle large-sized laser heads or the like).
On the other hand, JP-A 2000-30394 also discloses a structure in which the moving operation portion, which is connected to the first shutter member, is moved in the direction opposite to the time of opening the opening, and the first shutter member is rotated in the closing direction. However, the connecting portion, which connects the first shutter member and the moving operation portion, is structured as an elastic thin plate in order to convert the rectilinear direction moving force of the moving operation portion into circumferential direction moving force which rotates the first shutter member. Thus, no problems arise in the operation in the pulling direction (the direction of opening the opening), but it is easy for deformation such as buckling or the like to occur due to operation in the compressing direction. Therefore, in this disc cartridge, there are cases in which, when a disc medium is used, the opening which has been opened cannot be closed.
Further, as shown in
FIG. 27
, in the case of a disc cartridge
170
which
Hiraguchi Kazuo
Oishi Kengo
Chen Tianjie
Fuji Photo Film Co. , Ltd.
Sughrue & Mion, PLLC
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