JPH0620429A - Optical disk and cartridge - Google Patents

Abstract

PURPOSE:To enhance hermetic property and to enable the reduction in the thickness of the cartridge for housing the optical disk by confining the total sheet thickness of the transmitted light part of the cartridge and the optical disk to <=1.2mm. CONSTITUTION:The optical disk 2 constituted by forming a magnetic TbFeCo film on an about 0.3mm substrate is housed into the cartridge 1. The transmitted light part 6 formed on the cartridge 1 has 0.9mm sheet thickness. Polycarbonate (PC), polymethyl methacrylate (PMMA), etc., are used as the material of this part. The total sheet thickness of the transmitted light part 6 and the substrate is confined to <=1.2mm in such a manner, by which the recording and reproducing across the cartridge are enabled and the provision of the extremely thin optical disk cartridge is enabled. Further, the direct exposure of the disk to the outdoor air through a shutter is prevented and, therefore, the degradation in the reliability of the disk by the dust, etc., is extremely ameliorated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cartridge device, and more particularly, to improvement of a disk substrate and a cartridge shape of an optical disk, a magneto-optical disk, which performs only reproduction or recording / erasing by using a focused laser beam.

[0002]

2. Description of the Related Art Generally, as shown in FIG. 3, for example, a cartridge device of this type has a structure in which an optical disc C is accommodated in a cartridge B having a portion of an opening A and the opening A is opened and closed by a shutter D. Is configured. In many cases, the shutter D opens and the disc surface is exposed at the same time when the disc is inserted into the drive. As a result, the optical head E approaches the disk substrate CA. To the disk that started to rotate C
Since recording, reproduction or erasing of is performed over the board,
Like a hard disk or a floppy disk, the head is in direct contact with the recording medium, which deviates from the basic principle that the head is extremely close, so the optical disk is more resistant to dust and scratches than these magnetic media. It is said.

However, in reality, dust, scratches, etc. attached to the laser beam incident surface side have a possibility that the reproduction signal is lost or an unrecorded portion is generated and the reliability of the formed disk is greatly impaired. There is. Further, especially as the shutter D provided in the cartridge B is also opened and closed many times, dust or the like is expected to be generated from the sliding portion. In many cases, the plastic piece that is the cartridge material becomes dust, and thus adheres to the substrate due to the influence of electrification and the like, causing the above-mentioned troubles.

On the other hand, a magneto-optical disk using an exchange coupling film has been studied by various companies as it can be overwritten by optical modulation. This is because the coercive force Hc is small and the auxiliary layer having a high Curie point Tc and Hc is large.
Low recording layer. In a normal magneto-optical disk, recording is performed by oscillating a laser between the reproducing power and the recording power, but in the recording with the exchange coupling film, since the overwrite is performed, only the auxiliary layer is magnetized in one direction by the preceding magnetic field. Recording is performed by oscillating a laser between a high recording power capable of recording the entire recording film up to the auxiliary layer having a high Tc and a relatively low recording power for reversing only the recording layer having a low Tc. As a result, the overwriting is realized by the one-beam optical head and the two applied magnetic field generators. However, the problem here is the magnetization in one direction of the auxiliary layer in the preceding magnetic field. The conventional magneto-optical disk has a plate thickness of 1.2 mm.
Recording and playback are performed over the board. As shown in FIG. 4, by adhering two sheets with the recording film CB inside, the recording capacity per cartridge is increased.
However, since the applied magnetic field is also applied through the 1.2 mm substrate, there is a concern that the preceding magnetic field will be weakened. Since the strength of the magnetic field weakens as the cube of the distance, a fairly strong magnet F is required to apply the magnetic field over the substrate, and as a result, the size of the drive becomes large, especially the thickness direction of the disk becomes thick. Is concerned. To avoid this, it is possible to use a single plate without laminating the discs, but in addition to the deterioration of mechanical characteristics and the decrease of reliability, the recording capacity is half that of the pasting. Is inevitable. In terms of usability, the conventional double-sided method is a safe and attractive method. Further, as described above, an increase in the size of the device, in particular, an increase in the thickness of the drive itself in the thickness direction with respect to the disk has a possibility of having a great adverse effect when it is used by incorporating it into the system. Making it as thin as possible is one of the major challenges imposed on the drive.

[0005]

As described above, conventional optical discs, magneto-optical discs, and cartridges used for them are difficult to be thin, and dust or the like is caused by the sliding portion due to the opening and closing of the shutter. On the disk, and could significantly impair the reliability of the disk.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a cartridge device which enhances the airtightness of the disk itself in the cartridge without opening and closing the shutter provided in the cartridge.

[0007]

Therefore, in order to achieve the above-mentioned object, the present invention accommodates an optical disk in a cartridge and forms a thin transmitted light portion in a part of the cartridge. Further, when the sum of the substrate thickness of the optical disc and the thickness of the transmitted light portion is 1.2 mm or less,
And one of the thicknesses is greater than 0.1 mm, 1.
It is set to be smaller than 1 mm.

[0008]

As a result, it is possible to provide an extremely thin optical disk cartridge, which has been impossible in the past, because recording / reproduction is performed over the substrate, but it is performed not only by the substrate but also with the cartridge. Further, since the distance from the substrate incident surface to the recording surface is shortened, the one-way magnetization due to the preceding magnetic field used in the optical modulation overwrite using the exchange coupling film or the like is sufficient, and the size can be reduced.

Further, since the disk in the cartridge is not directly exposed to the outside air through the shutter and there is no sliding portion, the reliability of the disk due to dust etc.
It can be improved significantly.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to FIG. In the figure, reference numeral 1 is a cartridge formed of resin, for example, and an optical disk 2 is housed inside. Further, the transmitted light portion 6 is provided in a part of the cartridge 1, and the thickness thereof is set to be smaller than that of the other cartridge portions.

A specific example of this configuration will be described. The 1.2 mm thick polycarbonate (PC) substrate 2A has a thickness of 0.3 mm. As the material of the substrate,
(In addition to PC), Polymethylmethacrylate (PMM
In addition to plastic materials such as A), amorphous polyolefin (APO), and epoxy, a type in which glass or a plastic substrate surface by a sol-gel method is coated with glass can be used. Pay to. The transmitted light portion 6 prepared in the cartridge 1 has a plate thickness of 0.9 mm, and its material is polycarbonate (PC), polymethylmethacrylate (PMMA), amorphous polyolefin (APO), or plastic such as epoxy. In addition to the material, glass or a type in which a plastic surface by the sol-gel method is coated with glass may be used as long as it has little absorption at a laser wavelength (center wavelength is 750 to 830 nm) and sufficient transmission can be obtained. It has been confirmed that the ROM has a sufficient function in such a structure.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention is a write-once perforation type recording medium,
It is also applied to various recordable optical recording media such as rewritable magneto-optical recording media and phase change recording media. Here, the magneto-optical disk will be described.

A SiN protective film (about 1000 A) / TbFeCo magnetic film (about 200 A) / on a substrate of about 0.3 mm described above.
SiN protective film (about 250A) / aluminum alloy film (about 250)
A) was sequentially deposited by sputtering. This was inserted into the above-mentioned cartridge 1. The plate thickness of the cartridge transmitted light portion 6 is 0.9 mm and the material is polycarbonate (P
C), polymethylmethacrylate (PMMA), amorphous polyolefin (APO), epoxy and other plastic materials, as well as glass and those whose glass surface covers the plastic surface by the sol-gel method, the wavelength of the laser (center wavelength is (750 to 830 nm), there is little absorption and sufficient transmission can be obtained.

The disk thus prepared has a wavelength λ;
Recording and reproduction were performed using an optical head 5 having a numerical aperture NA of 785 nm and an objective lens. CN at recording frequency of 750 KHz and RBW of 10 KHz while rotating at a linear velocity of 1.3 m / s.
When R was measured, the noise level was about 1 dB higher than that of the conventional method, but a good signal-to-noise ratio CNR of 48 dB or more was obtained.

From the above, it was confirmed that recording / reproducing over a thin substrate and a cartridge can be performed without any serious problems.
In addition, this makes it possible to make a cartridge with a sealed structure, and pay attention to only the light transmitting part of the cartridge without paying attention to the adhesion of dust on the entire surface of the substrate. I have confirmed that it is good.

FIG. 2 shows an embodiment of the present invention, in which 2 is an optical modulation overwritable type magneto-optical disk using an exchange coupling film, 7 is a magnet, and 8 is a fixture for the magnet 7.

On a PC board having a plate thickness of 0.3 mm, S
iN protective film (about 750A) Recording layer TbFeCo (about 500A)
Auxiliary layer GaFeCo (about 1500A) SiN protective film (800
A) was sequentially deposited by sputtering. The exchange coupling membrane type magneto-optical disk thus obtained was inserted into the cartridge 1.

Then, the wavelength of this disk is λ; 785n
Recording and reproduction were performed by using an optical head having an objective lens numerical aperture NA of m. When the CNR was measured at a recording frequency of 750 KHz and RBW of 10 KHz while rotating at a linear velocity of 1.3 m / s, the noise level was about 1 dB higher than that of the conventional method, but a good signal-to-noise ratio C of 48 dB or more was obtained.
NR was obtained.

From the above, it was confirmed that recording / reproducing over a thin plate substrate and a cartridge can be performed without any serious problems.
In addition, this makes it possible to make a cartridge with a closed structure, and pay attention to only the cartridge transmitted light part 6 to prevent dust from adhering, without paying attention to dust adhering to the entire surface of the substrate. I'm confirming.
Also, the preceding magnetic field (7) at this time could only add about 500 Oe on the recording surface over the conventional 1.2 mm substrate, but by setting the substrate thickness to 0.3 mm, it is 2 KOe or more on the recording surface. It is now possible to obtain a sufficient magnetic field, and it is possible to obtain a sufficient preceding magnetic field with a small magnet even with a double-sided disc with a laminated specification.

[0020]

As described above, according to the present invention, by setting the substrate thickness and the total plate thickness of the cartridge transmitted light portion to 1.2 mm or less, recording and reproducing can be performed through the cartridge, and Since it is possible to reduce the thickness of the plate, it is also possible to reduce the size of the preceding magnetic field in optical modulation overwrite using an exchange coupling film.

As a result, by adopting such a structure, it is possible to reduce the thickness of the cartridge, which was about 9 to 11 mm in the past, to about 3 to 6 mm, so that the drive can be made smaller and thinner. Could be achieved.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of an essential part showing an embodiment of the present invention.

FIG. 2 is an enlarged sectional view of an essential part showing another embodiment of the present invention.

FIG. 3 is an enlarged cross-sectional view of a main part of a conventional example.

FIG. 4 is an enlarged sectional view of an essential part showing another example of the conventional example.

[Explanation of symbols]

 1 cartridge 2 optical disk 6 transmitted light section

Claims (2)

[Claims] 1. A cartridge device, wherein an optical disk is housed in a cartridge and a thin transmitted light portion is formed in a part of the cartridge. 2. The sum of the substrate thickness of the optical disc and the thickness of the transmitted light portion is 1.2 mm or less, and one of the thicknesses is set to be larger than 0.1 mm and smaller than 1.1 mm. The cartridge device according to claim 1.