JPH03141050A - Optical recording medium - Google Patents

Abstract

PURPOSE:To obtain the inexpensive optical recording medium which is excellent in recording characteristics and less changes with time by forming a recording layer on a substrate and forming guide grooves thereon by using a light absorptive resin. CONSTITUTION:The optical recording medium 10 is formed by successively laminating a protective layer 12, the recording layer 13, a protective layer 14, the light absorptive resin 15 having the guide grooves, and a protective layer 16 consisting of a transparent resin on the substrate 11. The layer 12 and the layer 14 are not always required and one or both thereof may not be formed. The medium 10 constituted in such a manner records, reproduces or erases information from the resin 15 side. Glass, resins, metals, etc., are, therefore, usable as the substrate regardless of the kinds of the substrates. The recording medium of a high transfer speed which can withstand high-speed revolutions is obtd. in this way. The recording medium is thus inexpensively produced with good productivity.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application 1] The present invention relates to an optical recording medium used in an optical memory such as an optical disk on which information is recorded and reproduced using laser light.

1 Jubei Fu 111 In addition to the well-known optical recording media that have guide grooves for tracking and have a recording layer formed on a substrate made of lath, acrylic, polycarbonate, etc., optical recording media that have a recording layer formed on a flat recording layer are There was an optical recording medium that formed a guide groove. 9th
As shown in the figure, this optical recording medium 90 consists of G G G
Y I G (Y 3 F e
It is composed of a magnetic net single crystal film 92 such as 5012), an ultraviolet curing resin 93 provided thereon and having a tracking guide groove, a reflective layer 94 such as AI, and a protective layer 95 such as 5i02. . The one-net magnetic film 92 has Tb
Fe=TbFeC.

Rare earth jl [! Since the absorption of light is smaller than that of the transfer metal 7M 7T alloy, the laser beam irradiated from the substrate 911Il passes through the magnetic net film 92 and is reflected by the reflection layer 94.The shape of the reflection layer 94 is transparent. Since it has an uneven shape that follows the guide groove of resin 71193, tracking can be performed using this guide groove. That is, the push-pull method is used to accurately trace the guide groove and perform recording and reproduction. When the laser beam is at the center of the guide groove, the diffraction pattern due to the tracking groove is symmetrical with respect to the center line of the track, so when the diffracted light is received by the bait m7 otodiode, its differential output becomes O. On the other hand, if the laser beam deviates from the center of the guide groove to the left or right, the diffraction pattern due to the tracking groove becomes asymmetrical, so that the differential output when received by the two-split seven-piece diode becomes a positive or negative output. Then, the position of the laser beam is feedback-controlled and tracking is performed so that the differential output of this two-divided 7t diode is always zero.

[Problem to be solved by the invention] However, the above-mentioned magnetism
In the iM recording medium, since it is necessary to use a single crystal for the recording layer, the substrate must have the same crystal structure as the recording layer and satisfy the conditions that the lattice constants are also approximately the same. For this reason, substrate materials are severely limited and generally expensive. Further, since such substrate materials generally have poor workability, it is extremely difficult to form tracking guide grooves on the substrate surface. Therefore, in order to perform tracking, it is necessary to form grooves with transparent resin and further provide a reflective layer, which complicates the manufacturing process, resulting in high cost and low reliability. In addition, in recording media using conventional grooved substrates, the recording layer has an uneven shape that follows the groove shape of the substrate, so the film thickness becomes uneven at the stepped portions and the bit shape may be distorted. There are problems in that the S/N ratio is lowered due to this and the recording layer deteriorates from the step portion.

[Object of the Invention] The present invention has been made in order to solve the above-mentioned problems, and its purpose is to form a flat recording layer on a substrate, and coat a light-absorbing resin on the flat recording layer. By constructing the groove using ff? and performing recording and playback from the resin side, ff?
The object of the present invention is to provide, at a low cost, a stable, high-quality optical recording medium that can use a wide range of substrate materials other than transparent substrates such as glass and resin, has excellent recording characteristics, and exhibits little deterioration over time.

[Means for Solving the Problems] In order to achieve this object, in the optical recording medium of the present invention, a flat recording layer is formed on a substrate made of plastic, resin, metal, ceramic, etc., and a light-absorbing layer is formed on the flat recording layer. The tracking guide groove is formed using resin. Then, information is recorded, reproduced, or erased from the light-absorbing resin side.

[Function] In the optical recording medium of the present invention having the above configuration, the tracking guide groove is formed using a light-absorbing resin,
Since the resin absorbs the irradiated light on the thick convex portion of the resin, the amount of light reflected from the recording layer becomes small as a result. On the other hand, in the recesses where the resin is thin, almost no light is absorbed, so the sufficiently strong light reaches the recording layer, and the amount of reflected light is also sufficiently large, making it possible to record and reproduce information and perform 7-ocusing servo. Tracking servo is performed by a three-beam method using the difference in the amount of reflected light due to the difference in thickness between the convex and four parts of the resin layer.Since the ttM is formed on a flat substrate, it is flat and uniform. Recording characteristics can be obtained, and step portions that cause film deterioration do not occur. Note that the light-absorbing resin layer with guide grooves can be manufactured at low cost and with high productivity using a normal grooved stamper, injection molding, or ultraviolet curing resin.

[Example] Hereinafter, an example embodying the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view of a main part of an optical recording medium 10 according to an embodiment of the present invention. S io on 11
2- Protective layer 12 such as Sio-AIN, Te,
Scraps 13 and protective layer 14 made of metals such as TeOx and TbFeCo, phase change recording materials, magneto-optical recording materials, dyes, etc.
, a light-absorbing resin 15 and a protective layer 16 made of a transparent resin.
are sequentially laminated.

Since information is recorded and reproduced from the side opposite to the substrate 11, the substrate 11 can be made of an opaque material such as metal or ceramic in addition to a transparent material such as glass or If resin.

In particular, by using ceramic for the substrate, it is possible to provide an optical recording medium that is lightweight, can be rotated at high speed, and is resistant to deformation and is stable.

Record! The i-layer 13 and the N-holding layers 12 and 14 on both sides thereof are produced by a well-known thin film forming method such as a vacuum evaporation method or a sputtering method. Note that the retainers 12 and 14 are not necessarily necessary, and one or both of them may be omitted.Since the surface of the substrate 11 is flat,
The recording layer 13 also becomes flat. As a result, there is no difference in the recording layer and the recording layer is formed with a substantially uniform thickness, so that uniform recording characteristics can be obtained, and film deterioration is less likely to occur, greatly improving reliability. Further, since there is no disturbance in the bit shape due to the step difference in the groove, there is no noise caused by the disturbance in the bit shape, and the S/N ratio is improved.

The light-absorbing resin layer 15 having guide grooves is formed, for example, as shown in FIG. 2. First, the same figure (a)
A protective layer 12 is formed on the substrate 11 as shown in FIG. Recording layer 13. Protective layer 1
First, as shown in FIG. 4(b), a metal stamper 21 in which grooves are previously formed in a spiral or concentric pattern is placed on the recording layer 13 and the recording layer 13. It is brought close to the substrate 11 on which the I layers 12 and 14 are formed, and a light-absorbing resin is injection molded into the gap. After cooling, the stamper 21 is removed, thereby forming the light-absorbing resin 15 having guide grooves 25 as shown in FIG. 2(e). Since the groove portion (concave g) 25 of the light-absorbing resin 15 is thin, the irradiated laser light reaches the recording M13 without being absorbed, and the reflected light from the recording W113 is hardly attenuated and is connected to the optical head (not shown). The light is received by The convex portion 26 of the light-absorbing resin 15 is the groove portion 25
Since it is sufficiently thick compared to the laser beam, the convex portion 26 is irradiated with
The intensity of the reflected light is absorbed by the light absorbing resin 15 before it reaches the recording layer 13, is further reflected from the recording layer 13, passes through the convex W626 of the light absorbing resin 15, and is reflected to the outside of the disc. become weak. In other words, the laser beam irradiated onto the groove portion 25 of the light-absorbing resin 15 is reflected without attenuation and the intensity of the reflected light is high, whereas the reflected light of the laser beam irradiated onto the convex portion 26 is The intensity becomes smaller and a difference occurs in the amount of reflected light.

Utilizing such a difference in the amount of reflected light, tracking is performed by a three-beam method as shown in FIG. Light beams 32, 33 approximately centered at are placed on both sides of the groove 25. When the beam 31 is at the center of the groove 25, the amounts of reflected light of the beams 32 and 33 are equal.

When the beam shifts to the right, the amount of reflected light of beam 32 decreases and the amount of reflected light of beam 33 increases.

Conversely, when the beam shifts to the left, the amount of reflected light of beam 32 increases and the amount of reflected light of beam 33 decreases. Therefore, by calculating the difference between the outputs of the reflected light quantities of the beams 32 and 33, a tracking error signal can be obtained and tracking servo can be performed.

As the light-absorbing resin 15, a resin mixed with a dye that absorbs light at the wavelength of the laser beam or an ultraviolet curing resin can be used. When using ultraviolet curing resin,
After pouring the resin between Fl and the stamper 21, it is cured by irradiation with ultraviolet rays to form grooves. Also, @Figure 4 (
As in a), use ultraviolet curing resin or 7 Otoresist 41! After applying the cloth, as shown in (b), a mask 45 with a pattern corresponding to the groove shape is applied, and by irradiating ultraviolet rays, only the irradiated parts are cured, and grooves are formed as shown in (c) of the same figure. In this case, the groove bottom 25 does not necessarily have to be provided as shown in FIG. 2(c). Further, the shape of the groove does not have to be rectangular as shown in FIG. 5, and may have rounded corners, for example.

The light-absorbing resin 15 may be made by dispersing carbon, metal particles, etc. instead of dyes in a transparent resin such as acrylic, epoxy, or ultraviolet curing resin. What is the thickness? The thickness is not particularly limited as long as it can absorb enough light for the llI portion (in other words, it is determined to be an appropriate thickness depending on the light absorption coefficient of the resin).

Note that the transparent N-layer 16 can be easily formed on the light-absorbing resin 15 by a method such as spin cord or injection molding. There are no particular limitations on the material and thickness of the transparent case 1171qlG. Also, the transparent protective layer is not necessarily required and may not be formed (although it is acceptable.) Although one embodiment of the present invention has been described in detail based on the drawings, the present invention may be practiced in other ways. For example, as shown in Figure @6, there is A between the substrate 11 and the protective layer 12.
A first reflective layer 61 may be provided, in which case the recording layer 13
The substrate 11 may be made of a material that is thin enough to allow the laser beam to pass through it, or made of a material that is polycrystalline, which increases noise but is highly translucent, such as magnetism. If a plate is used, the reflective layer 61 may be omitted.

As shown in FIG. 7, Ta is deposited on a substrate 71 made of glass or the like.

A1′! 4? Tracking guide 115! ? 2.5iO
A flattening layer 73 such as ZZ, a recording layer 74 such as Te, FeOx, TbFeCo, etc., and a protective layer 75 such as 5i02 are sequentially laminated. Furthermore, a reflective layer or light absorbing layer 76 such as A1 is formed to protect @M12. Note 1iJ113. Ho@I@14. Grooved light-absorbing resin 15. The transparent protective layer 16 may be formed sequentially. By doing so, recording and reproduction can be performed from both the substrate side and the light-absorbing resin layer side. Further, as shown in FIG. 8, recording layers 13 are provided on both sides of the substrate 11. Even if the light-absorbing resin 15 or the like is formed, recording and reproduction can be performed from both sides. Thereby, it is not necessary to bond two optical disks together, and a thin optical recording medium with high recording density can be provided.

Further, the shape of the substrate does not have to be a disk, but may be a card. In this case, the groove of the light-absorbing 1# resin may be formed parallel to one side of the card or in the shape of an arc.

Although other examples are not provided, the present invention can be implemented with various modifications and improvements based on the knowledge of those skilled in the art.

F. Effects of the Invention] As is clear from the detailed description above, according to the present invention, a flat recording layer is formed on a substrate, and a tracking guide groove is formed thereon using a light-absorbing resin. Since information is recorded, reproduced, or erased from the light-absorbing resin side, plastics, metals, ceramics, etc. can be used as the substrate, and any type of substrate can be used. It is possible to provide a recording medium that can withstand high-speed rotation and has a high transfer rate. *The light-absorbing resin is
It can be manufactured at low cost and with high productivity using an ordinary grooved stand bar, injection molding, or ultraviolet curing resin.

Furthermore, since the Ti dust is flat, uniform recording characteristics can be obtained and no step portions that cause film deterioration occur, so that the S/N ratio and reliability are significantly improved.

[Brief explanation of the drawing]

1 to PJ8 show embodiments embodying the present invention. FIG. 3 is an explanatory diagram showing a beam arrangement for tracking in the optical recording medium of FIG. 1, and FIG. FIG. 5 is a diagram illustrating an example of another method for manufacturing an optical recording medium, and FIG. 5 is a cross-sectional view of a main part showing a modified example of the light-absorbing resin of the optical recording medium of the present invention, and FIGS. 8 to 8 are main part sectional views showing a modified example of the optical recording medium of the present invention, and FIG. 9 is a main part sectional view showing an example of a conventional optical recording medium. 11... Substrate, 13... Recording layer, 15... Light absorbing resin.

Claims (1)

Claims: 1. An optical recording medium comprising a substrate, a recording layer provided on the substrate, and a light-absorbing resin provided on the recording layer and having a guide groove. 2. The optical recording medium according to claim 1, further comprising a protective layer provided on both sides or one side of the recording layer. 3. The optical recording medium according to claim 1, comprising: a transparent substrate;
a tracking reflective film provided thereon in a concentric or spiral shape; a flattening layer that substantially flattens unevenness caused by the tracking reflective film; and a first recording layer provided on the flattening layer. , a protective layer provided on the protective layer, a second recording layer provided on the protective layer, and a second recording layer provided on the protective layer.
1. An optical recording medium comprising a light-absorbing resin provided on a recording layer and having a guide groove.