Dynamic information storage or retrieval – Storage medium structure – Adjuncts or adapters
Reexamination Certificate
1998-06-19
2002-01-15
Nguyen, Hoa T. (Department: 2652)
Dynamic information storage or retrieval
Storage medium structure
Adjuncts or adapters
C360S133000
Reexamination Certificate
active
06339583
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a structure of a cartridge for accommodating an information-recording medium including a substrate made of resin or plastic. In particular, the present invention relates to a cartridge which makes it possible to avoid deformation during storage of an information-recording medium such as an optical recording medium and a magnetic recording medium accommodated in the cartridge.
2. Description of Related Art
Recently, a variety of high density information-recording media are commercially available, which are represented by compact disks (CD), magneto-optical recording media (MO), optical recording media such as digital versatile disks (DVD), and magnetic recording media such as hard disks. Usually, a substrate made of plastic such as polycarbonate is used for the optical recording media. Even in the case of the hard disk, it is known to use a plastic substrate formed with emboss type pre-pits.
Since the injection molding is available to produce the plastic substrate, the plastic substrate is suitable for mass-production. However, in view of the properties of the plastic substrate, the plastic substrate involves a problem that deformation such as warpage and flexure tends to occur as compared with substrates made of aluminum or glass.
A permissible standard value is specified for t he optical disk in relation to the deformation such as warpage. For example, in the case of a rotary type recording disk of 5.25 inches (133 mm), the permissible standard value for the amount of disk deformation is determined as a tilt in a direction toward the outer circumferential end from the center of rotation of the disk, which is not more than ±(diameter of disk recording medium)×sin((0.5 to 0.6)×2&pgr;/360), i.e., not more than about 0.58 to 0.70 mm.
If the deformation of not less than about 0.58 to 0.70 mm occurs, for example, in the optical disk or the magneto-optical disk of 5.25 inches (133 mm), the following trouble is caused. For example, when a magneto-optical disk having a diameter of 5.25 inches and a thickness of 0.6 mm is accommodated in a cartridge, a space of a slight width of 1.5 to 1.7 mm exists between the surface of the magneto-optical disk and the inner wall of the cartridge.
Therefore, when the disk having the radius of 67 mm is rotated, if the value of surface deflection caused by deformation of the disk becomes not less than 1.5 to 1.7 mm concerning one side (not less than 3.6 to 4.0 mm concerning both sides) in a direction perpendicular to the disk surface, then the disk collides with the cartridge, and the disk is possibly destroyed. It is also feared that the surface deflection may cause collision between the disk and the optical head or the magnetic head of the recording and reproducing apparatus during rotation of the disk, resulting in breakage of the disk or the head. Therefore, the deformation of the substrate relates to an extremely serious problem concerning the information-recording medium on which recording or reproduction is performed while accommodating the information-recording medium in a case or a cartridge.
For example,
FIG. 25A
shows a state in which a cartridge case
73
is allowed to stand perpendicularly, wherein a disk
1
produced with a plastic substrate is accommodated in the cartridge case
73
. In order to successfully rotate the disk
1
in the cartridge for the purpose of recording or reproduction, a gap is provided between the inner wall of the cartridge case
73
and the surface of the disk
1
. Therefore, as shown in
FIG. 25A
, the disk
1
leans obliquely against the inner wall in the cartridge case
73
which stands perpendicularly. In such an arrangement, for example, if the disk
1
is left for a long period of time in a situation in which the maximum temperature is not less than 40° C. and the maximum humidity arrives at 90% RH, the warpage
14
occurs in the vicinity of the outer circumference of the disk
1
as shown in FIG.
25
B.
As shown in
FIG. 26A
, if the cartridge case
73
is left to lean against the wall under a similar environmental condition, the warpage
14
occurs in the vicinity of the outer circumference of the disk
1
as shown in FIG.
26
B.
As shown in
FIGS. 27A and 27B
, it is assumed that a disk recording medium
1
is placed and stored in a cartridge
73
which has a stud
13
only at its inner circumferential portion. When the disk is thin, and the diameter of the stud
13
is small as compared with the diameter of the disk, then the warpage
14
has sometimes occurred at the outer circumference of the disk
1
as shown in FIG.
27
B. When such a cartridge
73
is left to lean obliquely against a perpendicular wall, if the environmental temperature and the environmental humidity are severe as described above, the deformation
14
of the disk
1
has occasionally occurred as shown in FIG.
28
.
Even in the case of a conventional disk produced by using a substrate made of resin such as polycarbonate and polymethyl methacrylate, when the disk has a large diameter, it is possible to counteract the deformation such as warpage by using a thick resin substrate. In the market, for example, the following characteristics are demanded for the medium at present and in future: i) the information-recording density is extremely high, ii) the dimension such as diameter and thickness is smaller, iii) the medium has a light weight and it is hardly broken, and iv) the medium is usable at high speed rotation. In order to satisfy the foregoing demands, for example, it is necessary for the magneto-optical disk that the thickness of the plastic substrate such as polycarbonate and polymethyl methacrylate is not more than 0.8 mm, especially not more than 0.6 mm. However, if the thickness of the plastic substrate is made thin as described above, the problem of deformation such as warpage becomes conspicuous.
In general, the warpage of the disk occurs when the medium is stored or used in an environment which is different from the environment of temperature and humidity during the production of the recording medium. It has been revealed that the larger the difference in environment is, the more conspicuous the warpage is. The magnitude of warpage differs depending on the difference in type of the plastic material of the substrate. It has been also revealed that the magnitude of warpage differs depending on the type and the thickness of the material for a protective film for coating the substrate.
SUMMARY OF THE INVENTION
A first object of the present invention is to provide a novel cartridge for accommodating an information-recording medium based on the use of a plastic substrate, which makes it possible to avoid any deformation such as warpage and flexure of the recording medium in the cartridge during storage even when the cartridge is stored in any posture.
A second object of the present invention is to provide a novel cartridge which makes it possible to avoid any deformation such as warpage and flexure of a recording medium as accommodated obliquely therein even when the cartridge is left to stand perpendicularly or even when the cartridge is left to lean against a wall.
A third object of the present invention is to provide a novel cartridge for accommodating an information-recording medium based on the use of a plastic substrate, in which the cartridge is prevented from such an arrangement that the cartridge stands perpendicularly or the cartridge leans against a wall.
According to a first aspect of the present invention, there is provided a cartridge for accommodating an information-recording medium, comprising:
a cartridge case on which a window for accessing the information-recording medium in the cartridge is formed;
a shutter used for opening and closing the window; and
a deformable elastic member provided on an inner surface of the shutter, for making contact with the information-recording medium accommodated in the cartridge case so that the information-recording medium is fixed in the cartridge case when the shutter is
Ohnuki Satoru
Ohta Norio
Shimazaki Katsusuke
Tsuburaya Yoshitane
Watanabe Hitoshi
Birch & Stewart Kolasch & Birch, LLP
Hitachi Maxell Ltd.
Nguyen Hoa T.
Watko Julie Anne
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