JPS59217244A - Information signal recording disk - Google Patents

Abstract

PURPOSE:To improve recording density and to prolong a reproduction time greatly by laminating plural recording surfaces and forming each recording surface of a different film which has a large reflection factor to light having specific wavelength and large transmissivity to light having other wavelength. CONSTITUTION:An optical disk 1 has the 1st recording surface 2A, the 2nd recording surface 2B, and the 3rd recording surface 2C, and the respective recording surfaces are superposed upon transparent layers 3 and 4. Further, 5 is a transparent substrate and 6 is a transparent projection layer. The recording surfaces 2A, 2B, and 2C are formed of different films 7A, 7B, and 7C. Namely, the film 7A has characteristics of light wavelength to reflection factor (a)(transmissivity(b)) shown by a graph curve I , the film 7B has characteristics shown by a graph curve II, and the film 7C has characteristics shown by a graph curve III. The 1st-the 3rd laser light sources 10A-10C emit light beams having wavelengths lambda2, lambda4, and lambda6 during reproduction to enter a selective operation state, and the recording surfaces 2A, 2B, and 2C on one side of the disk 1 are reproduced successively to increase the reproduction time by three times as long as before.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an information signal recording disk having a multilayer structure, which has a plurality of slightly smaller recording surfaces on which information signals are recorded so as to be read optically.

Prior Art Conventional optical video discs are disks with one recording surface on each side, and the playback time is 30 minutes per side at constant angular velocity (CΔV) and constant linear velocity (CLV).
) 60 minutes of playback is 6'i, it is impossible to make it longer than this.
(1) There was a problem (2) in relation to the recording density of the information signal.

Means for Solving the Problems The object of the present invention is to provide an information signal recording disk which solves the above-mentioned problems. In an information signal recording disk with two sides on the right side, a transparent layer is interposed between them, and a plurality of the above-mentioned recording surfaces are stacked and stacked, and each of the 11 recording surfaces is exposed to light of a different specific wavelength. It has a high rate of fouling, and it is outperformed by a structure made of a film with a low transmittance for light of other wavelengths.

Embodiment 11 FIG. 11 schematically shows an enlarged part of an optical disc 1 which is an embodiment of the information signal recording disc according to the present invention. 1 is a recording surface, 2B is a second recording surface, and 2G is a third recording surface, and each recording surface is formed in a stacked state with a transparent layer 3.4 in between. Further, 5 is a transparent substrate, and 6 is a transparent protective layer. Note that information signals are recorded on each recording surface 2Δ to 2C at a pitch of 1.
It is recorded as 0/no of ~.

In this case, each recording surface 2Δ, 2B, 2C has a different film 7A.
, 7B, and 7C. That is, the membrane 7Δ is
Figure 2 shows the relationship between the wavelength of light and the reflectance and transmittance.
As shown in graph line 1, the fouling rate is high for light with a wavelength within the range of wavelengths λ1 and λ3 (blue beam), and for light with a wavelength of λ1 or less and light with a wavelength of 23 or more (green beam). The film 7B exhibits a characteristic that the reflectance is small and the transmittance is low for light (green and red beams) within the range of wavelengths λ3 and λ25, as shown in graph line II. It has a characteristic of having a high reflectance for light beams), and a small reflection q4 coefficient and high transmittance for light with a wavelength of 23 or less (blue beam) and light with a wavelength of 25 or more (red beam). In addition, as shown by the graph line ■, the film 7C has a high reflectance for light with a wavelength within the wavelength range of λ5 to 27 (red beam), and has a high reflectance to light with a wavelength of λ5 or less (green beam and For blue beams) and light with wavelengths of 27 or more, the reflection rate is small and the transmittance is large.

J3, if a thin film with a high refractive index and a thin film with a low refractive index are alternately stacked on the base a80, in principle, the thickness of each film and the number of laminated layers will be different from each other, resulting in different wavelengths and opposite wavelengths. It is known that the 1 rate can be arbitrarily determined. ”-Membrane 7Δ, 7B
, 7G is based on the principle of , for example, ZnS with a refractive index of
The so-called crossed T7 layer ql+multilayer thin film 11 is constructed by appropriately laminating the thin films of MgF2 and MgF2 thin films having a small refractive index in a cross U manner so that each has the above-mentioned characteristics n1.

In the optical disc 1 having the structure No. 1, the recording surface has a multilayer structure formed in three layers, and the recording density is twice that of a conventional optical disc.

Next, the action of the reading laser beam on each of the recording surfaces 2Δ to 2G when reproducing the 11i optical disc 1 will be described.

FIG. 3 shows an optical system of an apparatus for reproducing the optical disc 1 mentioned above. In the figure, 10Δ is the first laser light source,
It emits light (blue beam) with wavelength λ2. 10B, IOC
is the second. They are third laser light sources, each having a wavelength of λ4 (
It emits light (green beam) and light with wavelength λ6 (red beam l\). These first to third light sources 10Δ to 10G of the optical disc 11 are selectively brought into operation as described below, and reproduce a predetermined recording surface of the optical disc 1.

First sea 1f light source 10ΔJ: The blue beam 11a of the lens system 12a, the grand Thomson prism 13a, λ
The optical disc 1 is irradiated through the 2/4 plate 14a, the Dyke mirror 15a, and the opposing lens 16. This blue beam lla is shown in Fig. 4.
The information signal on the first recording surface 2Δ0 is reproduced by this reflected light J:. At this time, the opposing lens 16 is controlled so that the blue beam 11a is focused on the film 7A.

A second laser light source 1 replaces the first radar light source 10A.
When 0B operates, the green beam 11b from this is transmitted through the lens system 12 +1, the ground 1-Muson prism 13b,
λ4/4 plate 14b, , dichroic mirror 15b
, the dichroic mirror 15a, and the objective lens 16 to irradiate the disc 1. This green beam 11b is
As shown in FIG. 11, the light passes through the film 7Δ and is reflected by the film 713, and the information signal on the second recording surface 2B is reproduced from this reflected light.

(At second glance, the objective lens 16 approaches the disk 1 side from the first recording surface of "-" during playback, and the green beam 111
) is focused on the film 7B1.

When the second laser light source 10[3 is replaced by the third laser beam KAi oc, the red beam 11 from this is activated.
C is lens system 12c, ground 1-Muson brism'
+ac, λ6/4 plate 1/Ic, dichroic 1' mirror 15c, 15b, 15a, objective lens 16
Then, the disc 1 is irradiated. This red beam 11 (]
As shown in FIG. 4, the light passes through WA7Δ, also passes through film 7B, and is reflected by film 7C, and the information signal on third recording surface 2C is reproduced from this reflected light. At this time, the objective lens 16 approaches the disk 1 side more than when reproducing the second recording surface as described above, and the red frame 11c is focused on the film '7 C0.
The focus is controlled so that

As a result, the above-mentioned disk 1 has the first .
Second. For example, the third recording surfaces 2A, 2B, and 2C are sequentially reproduced, and the reproduction time is twice as long as that of a conventional disc, which is a sufficiently long time.

Note 1. "J3 on disk 1 of 2, the first to third
Due to the existence of the transparent layers 3 and 4 between the recording surface 2△ and 2C,
A sufficient distance between each recording surface is ensured, and the spot of the green beam 11b on the first recording surface 2A and the spot of the red beam 11c on the first recording surface 2A are ensured. The spots on the second recording surfaces 2Δ, 2B are large. Therefore, the influence on the reproduced signal due to scattering and interference of the green beam 11b and the red beam 11C at the two recording points is i □00, ffi rl'l t
n months, 1°. 1.9 k. 6. . □To be done.

Next, regarding the manufacturing method of the optical disc 1, the 55th article
The explanation will be given with reference to Figures (Δ) to (1()). In each figure, parts corresponding to the constituent parts shown in FIG. 1 are designated by the same reference numerals.

First, the transparent plate 20 shown in FIG. 5 (△) is formed, and the transparent plate 20 shown in FIG.
[3) As shown in 1, apply lens] to this one surface.
A resist film 21 is formed by applying a resist film 21, which is exposed to beer as shown in FIG. , a transparent substrate is obtained according to the same figure ([).

Next, as shown in FIG. 1 (1), the transparent substrate 55 is
A film 7Δ is deposited on one surface of the recording surface 2Δ to form a first recording surface 2Δ. Next, as shown in FIG. 1 (G), a transparent layer 3 as a protective film is formed on the film 7Δ soil. After that, the same figure (13), one culm reaching the Nisu (G) is repeated twice, and the second recording surface 2
B. Transparent layer 4. A third recording surface 2C and a transparent protection Ft6 are formed, and the optical disc 1 shown in FIG. 1(a) is completed and covered.

It should be noted that the optical disc of the present invention is not limited to having three layers of the n() needle surface as in the above embodiments, but it is of course possible to have a recording surface of two layers or four or more layers. be.

In particular, an optical disk having a two-layer recording surface can be manufactured by the manufacturing method shown in FIG. That is, as shown in FIG. 6 (Δ), 1 stamper 3
0a, 3011, or by injection molding using the shaping mold 32 shown in the same figure (B'), one side has an uneven surface as shown in the same figure (C). A transparent thin plate 33 is formed, and then the same figure (D
), both sides of the transparent thin plate 33 are covered with films 34 and 35, and the first. Forming the second recording surface
A transparent protective layer 36 covering the membrane 34.35 as shown in E)
37, and the optical disc 38 is completed.

The structure of the information signal recording disk of the present invention can be applied to a so-called T1 impact disk in the case of an optical video disk.

Effects As mentioned above, according to the information recording disk No. 4R of the present invention, since it has multiple recording layers, the recording density of the information signal can be improved several times, and the playback time can be significantly extended. It has features such as being able to achieve

[Brief explanation of the drawing]

FIG. 1 schematically shows an embodiment of the information signal recording disk according to the present invention with a partially enlarged view. Figure 1 shows the reflection characteristics of the film with respect to the wavelength of light, Figure 3 shows the optical system of an example of a device for reproducing the disc in Figure 1, and Figure 4 shows the disc in Figure 1 during reproduction. 5(A) to (G1) are diagrams explaining the transmission/reflection state of each recording surface for the light beam, respectively, corresponding to the circle Q'? of FIG. 1. Figure 6 explaining the manufacturing method of No. 1.
Figures (Δ) to (F) 11 are diagrams illustrating a method of manufacturing an information signal recording disk in which a two-layer recording surface is printed respectively. 1... Optical disc, 2Δ... First recording surface, 2
B...Second recording surface, 2C...Third recording surface, 3° 4...Transparent layer, 5...Transparent substrate, 6...Transparent layer, 7Δ, 7B, 7G , 34.35... membrane, 10△・
...first laser light source, 10B...second laser light source, 10G...third rate light source, 11a...blue beam, 11b...green beam, 11C...red beam, 13a, 1311.13c - Ground t
−1==Son prism, 14 a −...λ2/'
l plate, 'l 411...λ, 1/4 plate, 1 /+
...λ6//i board, I Eia, 151),
15cm... Quick [21 Quick Mirror, 16...
Objective lens, 20... Transparent plate, 21... Lens 1~
Membrane, 3Qa, 301+... Stamper, 31... Transparent plate, 32... Molding! 1:(,33...transparent auxiliary plate. Figure 1 Figure 2

Claims (1)

[Claims] A recording surface on which an information signal is recorded so as to be read optically is placed on an information signal recording disk to the right, and a plurality of the recording surfaces are stacked one on top of the other with a transparent layer in between. It is characterized by the fact that the fouling rate for light of different specific wavelengths is large, and that it is formed with a film with a different transmittance for light of other wavelengths. Information signal line 1 recording disk.