JPH08221927A - Cartridge for optical disk - Google Patents

Abstract

PURPOSE: To make it possible to reproduce a CD and an optical disk thinner than the CD with a simple optical pickup by providing light incident parts of both surfaces with transparent members, providing the clamping part to a turn table with an aperture and covering these transparent members and the aperture with a shutter. CONSTITUTION: This cartridge encases the optical disk 140 in protective cases 120 and 121 and the light incident parts 152 of both surfaces are composed of the transparent members 110, 111. The shutter 150 is usually placed to cover and conceal the members 110, 111 and is constituted to slide to open only when being inserted into the optical disk device. Then, the adhesion of flaws and dust on the surface of the members 110. 111 is prevented and the high density optical disk of thin type is protected by the cartridge. As a result, the reproduction of the CD and the optical disk of sticking type thinner than the CD is reproduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention records signals at a density higher than the recording density of so-called compact disks (hereinafter abbreviated as CDs) among optical disks widely put to practical use for music, computer data, etc. Related to high density optical discs, especially by sticking two optical discs together,
The present invention relates to a cartridge for an optical disc that can be reproduced on both sides.

[0002]

2. Description of the Related Art An optical disk device such as an optical disk represented by a CD or a CD reproducing device narrows a laser beam emitted from a laser diode to its diffraction limit and irradiates a narrowed light spot on a pit row on the optical disk. The signal recorded on the optical disk is reproduced by detecting the change in the amount of reflected light. This CD has a diameter of 120 mm, the transparent substrate material is generally polycarbonate resin, and the thickness thereof is 1.2 mm. An optical reproducing device for reproducing a CD uses a near-infrared ray of 770 to 780 nm as a light source.
The numerical aperture (NA) of the objective lens that focuses the laser light on the optical disk using the diode is generally about 0.45.

On the other hand, the progress of the laser diode in recent years has been remarkable, and the laser diode for the red light having a wavelength of 630 to 690 nm has been put into practical use and combined with an objective lens having a numerical aperture of 0.55 to 0.6. Depending on the current CD 3 ~
A high-density optical disk having a recording density four times higher has been proposed (for example, 1993 Autumn Meeting of the Institute of Electronics, Information and Communication Engineers, Lecture No. C-364, "Examination of High-Density CD-ROM Using Red Laser Pickup"). However, the above-mentioned method has a problem that the numerical aperture of the objective lens is larger than that of the CD, and the tilt (warp) tolerance of the optical disc is half or less that of the CD. In order to solve this, the thickness of the transparent substrate of the optical disk is set to 0.6 mm, which is about half of the CD, and the allowable value for the inclination is set to about twice the thickness when the thickness of the transparent substrate is 1.2 mm.
Furthermore, a high-density optical disc has been proposed in which the signal recording surfaces of two optical discs are bonded together to double the recording density as compared with the case of a single plate.

It is desirable that an optical disk device for reproducing such a bonded high density optical disk can also reproduce a CD which has been widely put into practical use in the past, and an optical pickup used in this optical disk reproducing device is different in thickness by about twice. It is necessary to support two types of optical disks. Such an optical pickup is disclosed in JP-A-6-259804.

[0005]

In a high-density optical disc having a transparent substrate, which is thinner than a CD, bonded together, the diameter of the laser beam for signal reading on the surface of the optical disc is as small as about 60% that of a CD, and the reproduction signal is There is a problem that it is more susceptible to dust and scratches than a CD.

Further, the optical pickup disclosed in the above-mentioned prior art publication corresponds to two types of optical discs having different thicknesses, in order to reproduce a CD and a thin high density optical disc. And a light beam synthesizing means from each laser diode, and two photodetectors for independently detecting the reflected light from the optical disk of each laser diode. There is also a problem that the structure is more complicated than that of the optical pickup for CD used.

[0007]

In order to solve the above two problems, the present invention accommodates an optical disk in a cartridge. Also, in order to support two types of optical discs having different thicknesses with the same simple structure as a general optical pickup for CD, which is composed of one laser diode and one objective lens, a CD and a thin high density are adopted. A transparent member having a thickness corresponding to the difference in the thickness of each transparent substrate of the optical disc is provided on both sides of the cartridge, and an opening for engaging the optical disc and the turntable is provided. Further, in order to prevent dust from adhering to and scratching the transparent member, and to prevent dust from entering the inside of the cartridge, a shutter for covering the transparent member and the opening is provided.

[0008]

Since the optical disk is housed in the cartridge, it is possible to prevent dust from adhering and scratching. Further, since the reproduction of the signal of the high density optical disc is performed through the transparent member of the cartridge, if the optical pickup corresponding to the substrate thickness of 1.2 mm same as the CD is used, the high density optical disc having the thin transparent substrate is reproduced. be able to. It should be noted that the reproduction of the CD may be performed without inserting it into the cartridge as in the conventional case, and when inserting into the cartridge, a cartridge having no transparent member similar to the conventional cartridge may be used.

Further, according to the present invention, since the transparent members are provided on both sides of the cartridge, the high density optical disk of the pasting type can be applied. Also, 2 facing each transparent member
With one optical pickup, both sides of the optical disk can be reproduced simultaneously, or both sides can be reproduced without turning over the cartridge.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment of a cartridge for an optical disk according to the present invention. FIG. 1A is a plan view
FIG. 1B shows a cross-sectional view taken along the line AA ′ in FIG.

As shown in FIG. 1, in the cartridge of the present embodiment, the optical disk 140 has the protective cases 120 and 12.
It is stored in 1. Here, the light incident part 152 on which the laser light of the optical pickup of the protective cases 120 and 121 is incident is composed of at least the transparent members 110 and 111. The other part may be transparent or opaque. The optical disc 140 is, for example, a double-sided reproducible optical disc in which two optical discs having a thickness half that of an existing CD, that is, 0.6 mm, are stuck together. The total thickness of the optical disc 140 including the thickness of the adhesive layer at the bonding portion is about 1.
It is 2 to 1.3 mm, which is almost the same thickness as the CD.

If the transparent members 110 and 111 are exposed to the outside, the transparent members 11 can be stored or transported during storage.
There is a possibility that the surface of 0 or 111 may be scratched or dust may be attached. If the surfaces of the transparent members 110 and 111 are scratched or dusty, the level of the reproduction signal is lowered, or the reproduction cannot be performed when the reproduction signal is excessive. In order to prevent this, the transparent member 1
A shutter 150 for protection of 10, 111 is attached. The shutter 150 is configured to be slidable in both up and down directions in FIG. Here, S1 indicates the movable range of the shutter 150. Normally, the shutter 150
Is located so as to cover the central part, that is, the transparent members 110 and 111, and is opened only when it is inserted into the optical disk device. The opening / closing mechanism of the shutter 150 may be the same as that used in the existing optical disk cartridge.

Further, the cartridge of the present invention is provided with clamping openings 122 and 123 on both sides of the cartridge so that the turntable can be engaged from both sides.

FIG. 2 shows a state in which the optical disc housed in the cartridge of the present invention is being reproduced. In FIG.
The optical disc 140 is engaged with the turntable 232 by the disc retainer 230, and is rotated by the motor 240. The disc retainer 230 is built in the optical disc device, and after the cartridge is inserted, the disc retainer 230 starts from the top.
In this configuration, the 40 is fixed to the turntable 232. The optical pickup 210 is configured to read information recorded on the optical disc 140 through the transparent member 111,
Generally, it can be realized by an optical system widely used for CD.

As shown in FIG. 2, the transparent members 110, 11
1 is provided in each of the protective cases 120 and 121, and the openings necessary for clamping are provided on both sides, so that the cartridge has a vertically symmetrical configuration. Thus, by turning the cartridge over and putting it in the optical disk device, it is possible to perform double-sided reproduction without taking out the optical disk 140 from the cartridge.

Here, the total thickness of one of the transparent members 110 and 111 and the thickness of the transparent substrate on one side of the bonded optical disk 140 is 1.2 mm, which is the same as the CD, and the existing CD has no transparent substrate. By using a cartridge,
It is possible to reproduce two types of optical discs having different thicknesses by a simple optical system similar to the conventional optical pickup for CD including one laser diode and one objective lens. The CD may be omitted if it is not necessary to put it in the cartridge.

In the embodiment shown in FIGS. 1 and 2, the transparent members 110 and 111 are made of general plastic resin.
Alternatively, glass may be used, but it is necessary that the refractive index thereof is close to that of the transparent substrate of the optical disc 140, and polycarbonate resin generally used for optical discs is preferable.

When a material having high hardness is required for the transparent members 110 and 111 to prevent scratches,
Glass is preferred. In the case of a plastic resin, a polymethylmethacrylate resin has higher hardness than a polycarbonate resin and is suitable for preventing scratches. However,
Since the refractive index of polymethylmethacrylate resin is 1.49, which is smaller than 1.58 of polycarbonate resin, if the transparent members 110 and 111 are made slightly thicker than the case of polycarbonate resin, the refractive index difference is corrected. good.
In any case, the material of the transparent member is not limited to the above-mentioned one, and it is sufficient that it has a sufficient transmittance for the wavelength of the laser light used.

FIG. 3 shows a second cartridge of the invention.
FIG. 3 is a partial cross-sectional view showing an embodiment of the present invention, in which an optical pickup is shown for the sake of explanation. The same parts as those in FIGS. 1 and 2 are denoted by the same reference numerals. The cartridge of this embodiment has a structure in which a rotatable clamper 231 utilizing magnetic force is built in, and the optical disk 140 is engaged with the turntable 232 by the clamper 231.

FIG. 3 shows a method of reproducing the bonded optical disk 140 housed in such a cartridge.
As shown in FIG. 2, two optical pickups 210 and 211 may be provided so as to face the transparent members 110 and 111, respectively.
Alternatively, one optical pickup 210 may be moved so as to draw a U-shaped miracle T.

FIG. 4 is an enlarged partial sectional view of the cartridge shown in FIGS. Generally optical disc 140
Since the transparent substrate is a plastic resin molded product, it is always deformed such as warped. Here, the transparent member 11 has a value in which the distance a between the surfaces of the transparent members 110 and 111 of the cartridge which face each other is close to the total thickness b of the optical disk 140.
If the gap between 0 and 111 and the optical disk 140 is small, the rotating optical disk 140 may come into contact with the transparent members 110 and 111 or the protective cases 120 and 121 and be scratched. If the difference between a and b is large, the optical pickup is a system that reproduces the optical disk 140 through the transparent substrates 110 and 111, and therefore a large objective lens having a large working distance and a large effective diameter is required, and the servo lens is required. This is not a good idea because the shape of the actuator that drives the objective lens for control, the shape of other optical components of the optical system, and the shape of the entire optical pickup become large.

Generally, since the warp of the optical disk is about ± 0.2 mm to ± 0.8 mm when it is engaged with the turntable, the difference between the above a and b is 0.6 to 3 mm.
I just want it. Preferably an optical disc and transparent member 110,
In order to completely prevent contact with 111 or the protective cases 120 and 121 and use an objective lens having an effective diameter that is not so large, the difference between a and b is 0.8 mm to 2 mm.
The range should be

FIG. 5 shows the transparent member 111 and the protective case 12.
FIG. 3 is an enlarged partial cross-sectional view of a fixed portion with the first embodiment. Transparent member 1
Reference numeral 11 is fixed to the joint portion 310 of the protective case 121 by an adhesive, ultrasonic fusion, or the like. The outer surface 111 a of the transparent member 111 is covered with the shutter 150. The shutter 150 moves in the direction of arrow T2 when the cartridge is mounted in the optical disk device, but the outer surface 111a of the transparent member 111 and the shutter 150 are moved.
When the positions are close to each other, the outer surface 111a of the transparent member 111 may be damaged as the shutter 150 moves. Since the shutter 150 moves slightly away from or in contact with the surface 121a of the protective case 121 facing the shutter 121, the outer surface 111a of the transparent member 111 is shown in FIG. 5 rather than the surface 121a of the protective case 121 facing the shutter. It is desirable to be located inside.

FIG. 6 is a diagram showing the shapes of the transparent member 110 and the clamp opening 122. FIG. 6A shows
The area of the transparent member 110 and the opening 122 for clamping are separated. On the other hand, FIG. 6B shows the transparent member 110.
And the opening 122 for clamping are connected, and either shape may be used. Further, d is the transparent member 11
It has a width of zero. If this width d is too large, the transparent member 1
The size of the shutter 150 that protects 10 also increases,
The operation stroke of the mechanism for opening and closing the shutter 150 becomes large, which is not a good idea. Conversely, if it is too small, the transparent member 1
When fixing 10 to the protective case 120, distortion may occur in the portion through which the laser beam passes (generally the center of the transparent member 110), and the optical characteristics of the light spot for signal reproduction may deteriorate. Due to the above, the width d of the transparent member 110 is 10 m.
It is desirable to satisfy m or more and less than one third of the width of the entire cartridge.

FIG. 7 is a plan view showing a third embodiment of the optical disk cartridge of the present invention. The same parts as those in the above-mentioned embodiment are designated by the same reference numerals. Transparent member 11
The opening and closing range of the shutter 150, which is attached for the purpose of protecting 0, is limited to one side. Here, S2 is the shutter 15
The movable range of 0 is shown. When the shutter is opened and closed only on one side, when a spring or the like is used to urge the space between the protective case 120 and the shutter 150 for opening and closing, a mechanism similar to a floppy disk can be used. The other parts are the same as those in the first or second embodiment.

[0027]

As described above, in the optical disk cartridge according to the present invention, the transparent member is provided on both sides of the light incident portion, and the opening for clamping is provided to prevent the optical disk from being scratched or attached to dust. However, it is possible to reproduce a thin high-density optical disc and a conventional CD by using an optical pickup with a simple structure similar to that of a CD optical pickup, and to reproduce two recording surfaces of a bonded high-density optical disc. Will also be possible.

[0028]

[Brief description of drawings]

FIG. 1 is a first embodiment of a cartridge for an optical disc according to the present invention.

FIG. 2 is a diagram for explaining the operation of the present invention.

FIG. 3 is a second embodiment of a cartridge for an optical disc according to the present invention.

FIG. 4 is a partial cross-sectional view of a cartridge for explaining a positional relationship between an optical disc and a transparent member.

FIG. 5 is a partial cross-sectional view of a fixing portion between a transparent member and a protective case.

FIG. 6 is a partial plan view showing the shapes of a transparent member and an opening for clamping.

FIG. 7 is a third embodiment of the optical disk cartridge according to the present invention.

[Explanation of symbols]

110 and 111 ... Transparent members, 120 and 121 ... Protective cases, 122 and 123 ... Openings, 140 ... Optical disk, 150 ... Shutter, 152 ... Light incident section, 210 and 211 ... Optical pickup, 230 ... Disk holder, 2
31 ... Clamper, 232 ... Turntable, 240 ...
Motor, 310 ... Joint

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshifumi Takeuchi, 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Stock, Ltd., Hitachi Media Visual Media Research Institute (72) Inventor Yasuo Otsuka 292, Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Inside Hitachi Media Media Research Laboratories

Claims (8)

[Claims] 1. An optical recording medium formed on a transparent substrate is rotatably accommodated in a case having a transparent portion, the transparent portion is provided on both sides of the case, and the optical recording medium is a turntable. An optical disk cartridge, characterized in that an opening for engaging with is provided on both sides of the case, and an openable and closable shutter member capable of covering the transparent portion and the opening is attached. 2. The optical disk cartridge according to claim 1, wherein when the optical recording medium is rotatably housed in a case having a transparent portion, the distance between the mutually facing surfaces of the transparent members constituting the transparent portion is A cartridge for an optical disc, which is wider than the thickness of the optical recording medium by 0.6 to 3 mm, preferably 0.8 mm to 2 mm. 3. The optical disk cartridge according to claim 1, wherein the width of the transparent portions on both sides of the case is 10 m.
An optical disk cartridge characterized by being m or more and less than one third of the cartridge width. 4. The optical disk cartridge according to claim 1, wherein the transparent member forming the transparent portion is fixed to the case, and the surface of the transparent member outside the case is located inside the surface of the case in contact with the shutter member. An optical disk cartridge characterized by being located. 5. The optical disc cartridge according to claim 1, wherein a shutter member attached for the purpose of protecting the transparent portion opens and closes in both directions. 6. The optical disk cartridge according to claim 1, wherein a shutter member attached for the purpose of protecting the transparent portion is opened and closed only in one direction. 7. The optical disk cartridge according to claim 1, wherein the total thickness of the transparent member and the transparent substrate of the optical disk housed in the case is about 1.2 m on both sides.
An optical disk cartridge characterized by being m. 8. An optical recording medium formed on a transparent substrate is rotatably housed in a case having a transparent portion, the transparent portion is provided on both sides of the case, and the optical recording medium is a turntable. An optical disk cartridge, wherein an opening for engaging with the opening is provided on one surface of the case, and an openable and closable shutter member capable of covering the transparent portion and the opening is attached.