JP2001307378A - Optical recording medium and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical recording medium to be manufactured at low costs, wherein the problem, of the 'warping' of a board is solved is solved, a recording capacity is smaller than that of a normal DVD, and reproduction can be carried out by a DVD player. SOLUTION: Signal reading is preformed by a DVD player constructed in such a manner that one board 12 having a thickness of 0.6 mm is prepared, and the thickness of only a clamping area 14 is set larger by twice, i.e., a thickness of 1.2 mm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an optical recording medium, and more particularly, to an optical recording medium having a spiral or circular recording track formed on a signal recording surface around a central clamping area.

[0002]

2. Description of the Related Art There has been a demand for increasing the recording capacity of a CD (Compact Disc) which has been used as an optical recording medium for recording music signals, computer data, computer programs, and the like. To meet this demand, the two substrates are bonded together to change the wavelength of the light beam for reading, the numerical aperture (NA) of the objective lens of the optical pickup, or to use two signal recording surfaces. The structure has been studied, and as a result, DVDs (digital versatile discs) that have already been standardized and commercialized,
The wavelength of the light beam for reading is 650 nm (78 for CD).
0 nm), the numerical aperture (NA) of the objective lens of the optical pickup is set to 0.6 (0.45 for CD), and two substrates having a thickness of 0.6 mm are attached to each other to form a signal recording surface. I have two.

[0003] The reason that the DVD adopts the two-substrate bonding structure is to not only increase the recording capacity of the signal as described above, but also to prevent deterioration of the reproduced signal. That is, it is necessary for the laser beam of the optical pickup to be perpendicularly incident on the signal recording surface from the viewpoint of preventing deterioration of the reproduction signal, and the magnitude of this deterioration is inversely proportional to the cube of the light beam wavelength, It is proportional to the thickness of the disk substrate. FIG. 12 is a schematic diagram showing the effect of the inclination of the disc with respect to the optical axis on the diameter of the light spot. That is, it can be seen that the spot diameter is larger in the 1.2 mm thick disc due to the inclination than in the 0.6 mm thick disc. Therefore, the distance from the disk surface (light beam incident surface) to the signal recording surface is 1.2 mm for a CD, but is set to 0.6 mm and 0.6 mm for a DVD.
When the two substrates are bonded together, the directions of the warpage of the two substrates to be bonded are reversed in consideration of the directionality of the “warp” of the substrates, and the warpages of the two substrates are offset with each other. It has a structure that can be held down. FIG.
Shows a sectional view of a CD, and FIG. 11 shows a sectional view of a DVD.

[0004]

However, the structure for bonding two DVDs together has a complicated manufacturing process and causes high costs. That is, two molding machines were required in the production line, and two bonding machines were also required. In addition, there were many factors of high cost, such as the necessity of an adhesive for bonding. On the other hand, there is a demand for an application in which the capacity of a recording signal is not so required, that is, an optical recording medium having a relatively small size such as a business card size. Conventional business card size CD, ie CD using 1.2mm thick substrate
An optical recording medium recorded in a format has been known, but a small optical recording medium recorded in a DVD format suitable for recording a video signal or the like has not been known.

Accordingly, the present invention provides an optical recording medium which can be manufactured at low cost, has a smaller recording capacity than a normal DVD which has solved the problem of "warpage" of the substrate, and can be reproduced by a DVD player. The purpose is to:

[0006]

In order to achieve the above-mentioned object, according to the present invention, a substrate having a thickness of 0.6 mm is basically used for a DVD having two substrates having a thickness of 0.6 mm bonded together.
The thickness of the clamping area is doubled, that is, 1.2 mm, so that a DVD player can read signals.

That is, according to the present invention, a signal recording surface is provided on one surface of a substrate, and a thickness for holding the substrate in a disk drive of a reproducing apparatus is provided at the center of the substrate.
In an optical recording medium having a clamping area of 2 mm and having a spiral or circular recording track formed on the signal recording surface around the clamping area, the thickness of the outer peripheral part of the clamping area is zero. An optical recording medium is provided, wherein the signal recording surface is 0.6 mm and a portion of the signal recording surface at an outer periphery of the clamping area is located at a center in a thickness direction of the clamping area.

According to the present invention, a signal recording surface is provided on one side of the substrate, and a thickness of 1.2 mm for holding the substrate in a disk drive of a reproducing apparatus is provided at the center of the substrate.
In the optical recording medium having a spiral or circular recording track formed on the signal recording surface around the clamping area, the thickness of the substrate is 0.6 mm throughout, The adapter has a thickness of 0.6 mm attached to only the portion corresponding to the clamping area of the substrate, and the signal recording surface of the portion of the outer periphery than the clamping area,
An optical recording medium is provided, which is located at a joint surface between the substrate and the adapter in the clamping area.

Further, according to the present invention, a signal recording surface is provided on one surface of the substrate, and a thickness of 1.2 mm for holding the substrate in a disk drive of a reproducing apparatus is provided at the center of the substrate.
A method of manufacturing an optical recording medium having a clamping area of mm and having a spiral or circular recording track formed on the signal recording surface around the clamping area by injection molding of a synthetic resin, wherein the clamping is performed. The thickness of the outer peripheral portion from the area is 0.6 mm, and the signal recording surface of the outer peripheral portion than the clamping area,
A method for manufacturing an optical recording medium is provided, wherein a mold for performing the injection molding is configured so as to be located at the center in the thickness direction of the clamping area.

It is a preferable aspect of the present invention that the recording track formed on the outer peripheral portion of the clamping area is an annular portion having a width of about 1 cm or less in a radial direction. Further, it is one of preferred embodiments of the present invention that the substrate is a card type having a size of a business card. Further, the signal recorded on the recording track is D
Recording according to the VD format is one of the preferred embodiments of the present invention. Further, it is a preferable aspect of the present invention that the adapter is detachable from a portion of the substrate corresponding to the clamping area. Further, it is a preferable aspect of the present invention to have a rib on the surface opposite to the signal recording surface, the rib being engageable with the tray of the disk device.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view of an optical recording medium according to the present invention, and FIG. 2 is a sectional view taken along line II-II of FIG. 1 and 2, an optical recording medium 10
Although shown in substantially full size, it is configured as a so-called business card size card-type disc. Specifically, C
It is formed mainly of a substrate 12 manufactured by injection molding of PC (polycarbonate resin) similar to D and DVD. The optical recording medium 10 has a through hole 16 having a diameter of 15 mm at the center, a clamping area 14 having a diameter of 26 to 33 mm around the hole, and a semi-peripheral portion 13 at the outer periphery. The thickness of the clamping area 14 is 1.2 mm like a CD or a DVD, while the thickness of the outer peripheral half-thickness part 13 is half the thickness of the clamping area 14, that is, the thickness of one DVD layer. 0.6 mm.

The outer peripheral half thickness portion 13 is provided with a reflection film 20 at an annular portion around the clamping area 14. The signal recording unit 18 is provided with a width of about 5 mm in a portion corresponding to the inside of the annular portion of the reflection film 20. The signal recording unit 18 is configured by spiral or circular recording tracks, and one track is configured by a concavo-convex pattern (pits and lands) provided on the surface of the substrate 12. Printing can be performed on the lower surface of the substrate 12 in FIG. 2, that is, the entire surface where the clamping area 14 protrudes below the recording surface of the outer peripheral half-thickness portion 13 if desired. As with the label, it is possible to give various designs, guide recorded information, write a creator's name, or describe a reproduction method.

In order to manufacture an optical recording medium 10 having portions having different thicknesses as shown in FIGS. 1 and 2, PC is injection-molded using a mold corresponding to this. That is,
A step is provided on one side of the mold so that two thicknesses of 0.6 mm and 1.2 mm are formed. A mold prepared according to the size of the card mold can be used as the mold. However, using a conventional CD molding machine, clamping is performed so that the thickness of only the outer peripheral half-thick portion 13 is 0.6 mm. The auxiliary member may be inserted into the mold corresponding to the outer periphery of the area 14. In this case, an optical recording medium having a diameter of 8 cm or 12 cm is formed. After the molded body is removed from the injection molding machine, a cutting process is performed to obtain the size and shape of the card mold.

The molten PC resin injected into the mold is cooled and molded while applying pressure, and this cooling is performed by a cooling device that cools the mold from the surroundings.
Since the entire disk is cooled at a uniform cooling rate during the cooling process, deformation and warpage of the disk after cooling can be prevented. In order for the entire disk to be cooled at a uniform cooling rate, in addition to using a mold designed so as not to cause heat imbalance, the injection speed, injection amount, It is necessary to appropriately control the applied pressure and pressurizing time, the temperature of the cooling water of the cooling device, and the like. If these conditions are satisfied, even if the thickness of the outer peripheral half-thickness portion 13 is only 0.6 mm, deformation and warping after molding are extremely small, and the values interfere with reading by an optical pickup. Not tolerable.

FIG. 3 is a perspective view of a mold for manufacturing the optical recording medium 10 of the present invention by injection molding, and FIG. 4 is a sectional view showing the internal structure of one mold. As shown in FIG. 4, a cooling circuit is provided at a position near the stamper in the mold. FIG. 5 is a schematic diagram showing a preferred configuration example of the cooling circuit. In this example, the cooling circuit has concentric piping. In the figure, the black dots indicate the intersections of the pipes. FIG. 6 is a schematic diagram showing another preferred configuration example of the cooling circuit. In this example, the cooling circuit has a spiral pipe. By using the mold having the cooling circuit having the configuration shown in FIGS. 5 and 6, the above-described heat imbalance does not occur.

One example of preferable molding conditions is as follows. Mold temperature: 105 ± 5 ° C Resin melting temperature: 350 ± 30 ° C Clamping force: 20 ± 10 ton Resin measuring position: 15 ± 0.5mm Filling pressure: 1600 ± 100 kgf / cm ² Filling speed (maximum): 180 ± 20mm / s Mold cooling time: 2.8 ± 0.2s

FIG. 7 is a plan view showing another embodiment of the optical recording medium according to the present invention, and FIG. 8 shows an optical recording medium 10A according to another embodiment mounted on a tray 26 of a disk device. FIG. In this embodiment,
It differs from the embodiment shown in FIGS. 1 and 2 only in the following points. That is, an arc-shaped rib 24 is provided on one surface of the optical recording medium 10A, that is, on the surface opposite to the side from which the clamping area 14 protrudes (on the surface opposite to the signal recording surface). I have. The rib 24 protrudes from the flat surface, and as shown in FIG.
Is provided for engaging and positioning with the inner wall of the dent. With such a configuration, when the optical recording medium 10A is loaded into the disk device and rotated, the disk is rotated in a more stable state.

FIG. 9 shows the distance between the optical pickup 22 of the reproducing apparatus and the signal recording surface of the optical recording medium 10 having the signal recording section when reading out a recording signal or data using the optical recording medium 10 of the present invention. FIG. 3 is a schematic diagram for explaining the comparison with the case of a DVD. FIG. 9A shows the case of the optical recording medium 10 of the present invention, and FIG. 9B shows the case of a DVD. In these figures, the disk optical pickup 22
On the side with the disk drive spindle (not shown)
It is assumed that the disc is fitted in the center hole of the disc, and a disc clamp (not shown) exists on the side where the optical pickup 22 is not provided to press the disc. In any case, the distance L between the objective lens (not shown) of the optical pickup 22 and the signal recording surface is the same distance, and a signal can be read from the optical recording medium 10 of the present invention by a conventional DVD player. I understand.

When the optical recording medium 10 of the present invention is of a card type as shown in FIG. 1, it can be easily handled like a business card, and is convenient to carry and store. In particular, it records and provides introductions of individuals, companies and organizations, business and products, along with video and audio, guides to websites and e-mail destinations, and records software that automatically connects to websites. You can keep it.

In the above embodiment, the clamping area 14 and the outer peripheral half-thickness part 13 are described as being integrally formed. However, the clamping area 14 and the outer peripheral half-thickness part 13 are formed to have a uniform thickness of 0.6 mm. It is molded to a thickness, and a 0.6 mm thick annular adapter corresponding to the clamping area 14 is attached. The thickness of the clamping area 14 is set to 1.2 mm as in the above embodiment. Can be. In order to make this adapter detachable, the adapter and the portion where the adapter is mounted can be provided with recesses and protrusions that can be fitted. If the adapter is detachable, it is convenient to always carry the card type recording medium having a thickness of 0.6 mm by keeping the adapter in the player.

In the above-described embodiment, an example is shown in which the present invention is configured as a card-type optical recording medium having a business card size. In addition to the shape, a desired shape such as a shape of an animal or a plant or a geometric shape can also be used.
Although the above embodiment has been described as a read-only optical recording medium, the present invention is not limited to this, and can be applied to a recording disk and a disk for both reading and recording. Further, the optical recording medium in the present invention includes a so-called magneto-optical recording medium.

[0022]

As described above, according to the present invention, instead of bonding two substrates having a thickness of 0.6 mm as in a conventional DVD, the substrate portion on which the signal recording surface exists is 0.6 mm.
Since the thickness is made to be 1.2 mm thick, only the clamping area is doubled, the number of conventional equipment for bonding two sheets, that is, the number of molding machines and bonding machines can be reduced. The simplification and the need for an adhesive for bonding are unnecessary, and a decrease in the yield that occurs in the bonding step can be prevented. Therefore, according to the present invention, an optical recording medium that can be reproduced by a DVD player at low cost can be provided.

Further, since the optical recording medium of the present invention does not use an adhesive for bonding, jitter due to rotation unevenness, which is one of the causes of non-uniformity of the adhesive, is improved, and image quality to be reproduced is improved. Sound quality and data reliability are improved. Furthermore, since the weight is smaller than that of the two-plated disc, the load on the player is reduced, the power consumption is reduced, and the failure of the drive mechanism is reduced. In addition, since the main part of the disk is thin, the package can be simplified, and there is a secondary effect that various types can be adopted.

[Brief description of the drawings]

FIG. 1 is a plan view of a preferred embodiment of an optical recording medium according to the present invention.

FIG. 2 is a sectional view taken along line II-II of FIG.

FIG. 3 is a perspective view of a mold for manufacturing the optical recording medium according to the present invention.

FIG. 4 is a sectional view of one side of the mold of FIG. 3;

FIG. 5 is a schematic diagram showing a preferred example of the cooling circuit shown in FIG. 4;

FIG. 6 is a schematic diagram showing another preferred example of the cooling circuit shown in FIG. 4;

FIG. 7 is a plan view of another preferred embodiment of the optical recording medium according to the present invention.

8 is a cross-sectional view taken along the line VIII-VIII of FIG. 7, and is a view showing a state where the player is on a tray of the disk device.

FIG. 9 shows the distance between an optical pickup of a reproducing apparatus and a signal recording surface having a signal recording section of an optical recording medium when reading out a recording signal or data using the optical recording medium of the present invention. It is a schematic diagram for comparatively explaining.

FIG. 10 is a sectional view of a CD.

FIG. 11 is a sectional view of a DVD.

FIG. 12 is a schematic diagram for explaining the difference in the influence of the inclination due to the thickness of the disk.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Optical recording medium 12 Substrate 13 Peripheral half thickness part 14 Clamping area 16 Through hole 18 Signal recording part 20 Reflective film 22 Optical pickup 24 Rib 26 Tray

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Claims (8)

[Claims] 1. A substrate having a signal recording surface on one side thereof, a clamping area having a thickness of 1.2 mm for holding the substrate in a disk drive of a reproducing apparatus in a central portion of the substrate, In an optical recording medium in which a spiral or circular recording track is formed on the signal recording surface around the clamping area, a thickness of an outer peripheral portion from the clamping area is 0.6.
an optical recording medium, wherein the signal recording surface is located at a center of the clamping area in a thickness direction of the clamping area. 2. A substrate having a signal recording surface on one side thereof, and a clamping area having a thickness of 1.2 mm for holding the substrate in a disk drive of a reproducing apparatus at a central portion of the substrate, In an optical recording medium in which a spiral or circular recording track is formed on the signal recording surface around the clamping area, the thickness of the substrate is 0.6 mm throughout, and corresponds to the clamping area of the substrate. Has an adapter with a thickness of 0.6 mm, which is attached only to the part to be overlapped,
An optical recording medium, wherein the signal recording surface at a portion outside the clamping area is located at a joint surface between the substrate and the adapter in the clamping area. 3. The optical recording according to claim 1, wherein the recording track formed on an outer peripheral portion of the clamping area is an annular portion having a width of about 1 cm or less in a radial direction. Medium. 4. The optical recording medium according to claim 1, wherein the substrate is a card of approximately business card size. 5. A signal recorded on the recording track,
5. The optical recording medium according to claim 1, wherein the optical recording medium is recorded according to a DVD format. 6. The optical recording medium according to claim 2, wherein the adapter is detachable from a portion of the substrate corresponding to the clamping area. 7. The optical recording medium according to claim 1, further comprising a rib on a surface opposite to the signal recording surface, the rib being engageable with a tray of a disk device. 8. A substrate having a signal recording surface on one side thereof, a clamping area having a thickness of 1.2 mm at a central portion of the substrate for holding the substrate in a disk drive of a reproducing apparatus, In a method for manufacturing an optical recording medium having a spiral or circular recording track formed on the signal recording surface around the clamping area by injection molding of a synthetic resin, Is 0.6
mm, and the mold for performing the injection molding should be configured so that the signal recording surface of the outer peripheral portion from the clamping area is located at the center in the thickness direction of the clamping area. Characteristic method for producing an optical recording medium.