Disk cartridge

Details Disk cartridge Disk cartridge

2001-06-13

2003-11-25

Cao, Allen (Department: 2652)

Dynamic information storage or retrieval

Storage medium structure

Adjuncts or adapters

C360S133000

Reexamination Certificate

active

06654338

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates to a disk cartridge, such as an optical disk cartridge or a magnetic disk cartridge and the like, and more particularly to the structure of a disk cartridge in which a large type head may be used.
In recent years, along with the accelerating development of multimedia, optical information recording drives capable of recording a large quantity of data in high density and reproducing them at high speed are attracting a great deal of attention. These optical information recording drives include a read-only type optical disk, such as a CD or a laser disk, on which information is stamped on the disk at the time of producing the disk which thereafter permits only reproduction of the recorded information, a write-once type optical disk, such as a CD-R, which permits only once recording, and a rewritable type optical disk which permits rewriting and erasing of data without limitation by utilizing photomagnetic recording or phase change recording. Of these available types of optical information recording drives, optomagnetic recording drives are mainly used in the field where a high data transfer rate is required.
Recording and reproduction of data use a light spot obtained by narrowing down a laser beam to the diffraction limit of the lens. The size of this light spot is almost equal to &lgr;/NA, where &lgr; is the wavelength of the laser beam and NA, the numerical aperture of the lens. Recording and reproduction in higher density, i.e. of a smaller pattern, requires a correspondingly smaller light spot.
In order to reduce the size of the light spot, the numerical expression of &lgr;/NA teaches two manners: one decreasing the wavelength &lgr; of the laser beam, and the other of increasing the numerical aperture NA of the lens. The lens numerical aperture NA, represented by NA =sin &thgr; where &thgr; is the half diaphragm angle, is smaller than 1.
In any optical information recording drive currently in practical use, the numerical aperture NA of the objective lens is at most about 0.6. This is because, as the numerical aperture NA increases, the coma and the astigmatism aberrations become greater in a state wherein the optical axis of the objective lens is inclined with respect to the substrate.
In order to solve this problem, it is essential not only to reduce the thickness of the transparent layer which the light passes (corresponding to the thickness of the transparent substrate in conventional optical information recording drives) but also to prevent the optical axis of the objective lens from being inclined with respect to the transparent substrate. For this purpose, there is proposed an optical information recording medium, together with a manufacturing method thereof, having grooves and pits for obtaining signals at the time of tracking and address signals formed on the transparent substrate, a recording layer including a reflective layer formed over them and a transparent resin layer of about 0.1 mm in thickness further formed over it. Recording and reproduction of information are accomplished by pressing a slider which mounts an objective lens and the like, against the surface of the transparent resin layer of this information recording medium (see JP-A-8-235638).
This optical information recording medium, however, there arises a problem that, because the slider is moved while being pressed against the transparent resin layer, the friction between the slider and the transparent resin layer is apt to result in scratching the transparent resin layer.
Moreover, the transparent resin layer over the recording layer is formed by either spin-coating it with ultraviolet setting resin or adhering a transparent resin film to it. Where a transparent resin film is to be adhered, it has to be ensured that no air pockets or bubbles are formed between the film and the recording layer, but this requirement poses a productivity problem.
Furthermore, where the ultraviolet setting resin coat is to be formed in a thickness of about 0.1 mm, the viscosity of the resin should be set considerably higher than usual, because this thickness is about five to ten times as great as the 10 to 20 &mgr;m thickness of a usual protective layer for an optical information recording medium. In this case, there are problems about the uniformity of the transparent resin layer and of possible generation of bubbles from air rolled in, which entail productivity and yield implications as in the case of adhering a transparent resin film.
On the other hand, a near field optical recording/reproducing system is proposed, by which light is focused on an information recording medium via a solid hemispherical lens (SIL), the distance between the SIL and the surface of the optical information recording medium is set to be about ¼ &lgr; (&lgr; is the wavelength of the laser beam), and the NA of the objective lens is effectively enhanced by using near field light (see U.S. Pat. No. 5,125,750).
However, in this system again, where the wavelength of the laser beam is 650 nm, the distance between the bottom surface of the SIL and the surface of the optical information recording medium is as little as 160 nm, which implies the problem of possible scratching of the surface of the optical information recording medium by the SIL. As a consequence, the cartridge to accommodate the disk has to be designed to minimize sticking of dust to the disk surface when the disk is not in use.
On the other hand, these recording systems allow recording onto and reproduction from both sides of the disk. However, this entails doubling of the height and size of the head, which is particularly unavoidable in the optical assist magnetic recording/reproducing technology, which is expected to make possible even higher density for information recording media.
This optical assist magnetic recording/reproducing technology is intended to achieve both high line recording density, an advantage of vertical magnetic recording, and high track density, a feature of optical recording by irradiation with a laser beam in an assisting way at the time of vertical recording/reproduction (see the Journal of the Magnetics Society of Japan, Vol. 23, No. 8, 1999).
This problem has led to a requirement for a disk cartridge having a large head inlet, but a conventional disk cartridge has a rectangular head inlet formed as a block in a prescribed position of a cartridge case. Where an enlarged head is to be used on account of the above-described background circumstance, the surrounding portions of the case demarcating the head inlet would pose obstacles, which a disk cartridge loaded into the recording/reproducing apparatus might collide against and thereby give rise to various troubles.
FIGS. 19 and 20
are drawings illustrative of a disk cartridge proposed in the Japanese Utility Model Laid-Open No. 4-26463 specification. This disk cartridge is provided with an upper case
100
a
and a lower case (not shown) constituting a cartridge case
100
and to be separable from each other in the vertical direction. In respectively prescribed positions of the cartridge case
100
, there are formed a head insertion inlet
101
and a spindle insertion inlet
105
, and a recording disk
102
is accommodated rotatably within the cartridge case
100
.
A shutter
103
for opening and closing the head insertion inlet
101
is arranged slidably on the cartridge case
100
. When a disk cartridge is inserted into a disk drive unit, the shutter
103
shifts in a direction orthogonal to the direction of disk cartridge insertion, and the head insertion inlet
101
and the spindle insertion inlet
105
are opened. To the front and rear ends of the shutter
103
is connected a slider
104
to make the shutter
103
more slidable. The upper case
100
a
and the lower case are elastically energized by a spring member (not shown) in the direction of joining each other, and at the same time they are separated in the vertical direction by the shifting of the slider
104
.
This disk cartridge involves an inconvenience that, where a larger

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