JPS5845633A - Information recording medium - Google Patents

Abstract

PURPOSE:To obtain a medium with less deformation of secular change such as warp and strain, low cost, high shape-stability and excellent strength, by bonding two bases having an information recording layer at least on one base, taking the layer as the inside. CONSTITUTION:The 1st base 5 made of a synthetic resin is provided with an added layer 6 made of a photo-setting resin and an optical recording layer 7 is vapor-deposited on the surface. An added layer 6' made of the photo-setting resin is similarly provided for the 2nd base 5' using the same type of material as the 1st base 5, and both are bonded with a photo-setting type adhesive 8. Thus, since the absorption factor and coefficient of thermal expansion of the bases 5, 5' and the layers 6, 6' are equal, allowing to decrease the deformation such as warp and strain due to secular change.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a disc-shaped information recording carrier used in optical recording or reproducing systems, and is intended to reduce and eliminate mechanical deformation over time such as warpage.

In the optical recording and reproducing method, a laser beam corresponding to an information signal is irradiated onto the optical recording layer of a rotationally driven disc-shaped information recording carrier (hereinafter referred to as a disk) by a J-rotator.
The optical recording layer is provided with optical shading or C1, and unevenness to record and reproduce information, and it is possible to record minute signals of several 111 nanometers. This is a method that allows density recording.When recording and reproducing the deceased,
There is no contact between the laser light pickup and the disk, so there is no wear, and it provides multi-functions such as still images and high-speed search. It is suitable for industrial use, such as still image files and document files.

It is also being put into practical use for commercial purposes. A disk for such use may be used for a long period of time with the disk mounted on a deck, that is, with only the center portion of the disk held. In such cases, the disc will deform, and if this deformation is too thick, it will not only be impossible to record or play back, but also there is a risk of losing important information. It is essential that the material has sufficient strength.

- Also, the optical recording layer itself has a weak mechanical strength and is easily damaged, so care must be taken when handling it.Depending on the reproduction method, there may be dust on the recording layer. It causes clarity.

Therefore, as shown in FIG. 1, a transparent substrate 2-1- on which an optically readable information structure 1 is formed is conventionally coated with a layer 3 for protecting against dust particles, color (...and Itt scratches). It is considered that a synthetic resin sheet or film coated with an adhesive 4 on one side can be pasted as a protective layer 3, and Figure 1 a shows a substrate 2. The recording layer 1'' containing the information structure is protected by spraying an organic polymer onto the surface of the recording layer 1''.

Nowadays, when irradiating the laser beam from the protective layer 3 side when reading the personal record, the focus of the objective lens is controlled and moved so that the beam is focused on the information structure.
J-runo? Therefore, the thickness of the protective layer 3 is over the entire surface.
It is safe that j'+'. On the other hand,
When irradiating ``J'' beef from the substrate side of the recording body, it is not necessary to satisfy strict conditions such as the protective layer 3.

However, in all of these cases, a protective layer made of a material and size with different physical properties is provided as part of the recording phase, and its asymmetric structure makes it difficult to withstand high temperatures and high humidity. 7. Not only under special environments, but also under normal environmental changes.
Shape deformation is likely to occur even after one stroke.

In FIG. 2, a substrate 2 provided with an information structure 1 and a substrate 2' provided with an information structure 1 having approximately the same thickness are combined with an intermediate protective layer 3' to form an integrated unit. It is a ζ thing. There are two substrates 2°2 shells, water absorption, heat 11i tensile coefficient, etc. 111! Irrespective of symmetry regarding constants and moisture absorption state, there is no particular problem with the balance of mechanical strength of the two substrates as long as they have approximately the same thickness 1111. However, this 1: U-shaped information recording carrier is not suitable for special environments of high temperature and high humidity, and during manufacturing,
Even if there is a normal use line Y (71?) after assembly, deformation such as warping and distortion is likely to occur over time, and there are many cases where it becomes unusable.

The present invention eliminates the following drawbacks, and the mechanical strength, moisture absorption state, physical properties, etc. of the two discs are
In order to have a symmetrical structure, it can be used not only under normal usage conditions, but also in special environments of high temperature and humidity.
The present invention provides a structure of a one-piece information recorder with low cost, high shape stability, and excellent strength, with little deformation over time of warping and straining even when the information is used.

The first embodiment of the present invention will be explained with reference to the drawings.

In FIG. 3, a first substrate 6 made of synthetic resin is provided with a photocurable resin layer 6, and an optical recording layer on the surface of which can be partially recorded by laser light. Y
is deposited. A second substrate 5' made of the same material as the first substrate 6 is coated with a similar additional layer 6 of photocurable resin.
' is provided and both are bonded by a photocurable adhesive 8. - On the second board 6']:
To protect the optical recording layer provided on the first substrate 6 from dust and damage, there is no need to take great care in handling.

′? )/In this case, since the laser beam 9 is irradiated through the first substrate 6 as shown in the figure, there is no need for the protective layer to satisfy strict conditions such as thickness.

Further, the first and second substrates are made of the same material, have the same water absorption rate and coefficient of thermal expansion, and have symmetrical mechanical strengths with respect to the adhesive layer. Here, mechanical strength is the elastic constant of the single synthetic resin that forms the substrate.

It means only mechanical physical constants such as bending strength, so r4,
3, which refers to the overall mechanical strength of each of the disks including the optical recording layer and additional layer on the first and second substrates excluding the adhesive layer 3. For example, including the optical recording layer 7 and the additional layer 6. If the flexural rigidity of the first substrate 6 is D + Kl/mJ, then the flexural rigidity D 2 Kj7/mi of the second substrate 5' including the additional layer 6' is equal to Dl or at least 0.9 D+ < D2 <
1, it is necessary to have a mechanical strength equivalent to ID+. Note that the symmetry of the mechanical strength here does not necessarily imply the geometrical symmetry of structure 1-7.
(J, I don't.

In this case, except for the evaporation process of the optical recording layer, the 4A groups always have the same history in the manufacturing process, so the moisture absorption state and the heat generated in the additional layer are likely to occur. The amount of curing shrinkage is also symmetrical, and warpage and strain after assembly can be used without problems such as I7: J and A7.1, Sr-9
In addition, the water absorption rate and coefficient of thermal expansion of the substrate and the supporting layer are the same, so there is little deformation over time such as warping and distortion, not only under normal usage conditions but also under special environments such as high temperatures and high temperatures. , there is no hindrance to optical fr recording/11f raw.

The j isk kl2 with this structure is classified into warpage, rough warpage (S11 average value of the amount of warp) and wavy warp (amount of warp in the circumferential direction). 160 p m + wavy sled l-100
Things within μm have been adequately evaluated. Furthermore, it has been confirmed that even in a special environment of high temperature and high humidity, for example, at 60°C and a 90V row f1, there are almost no rough-textured trees exceeding 150ltnl. Ta. These changes in warpage over time are within a range that can be sufficiently tracked by the optical system.

The additional layer 6 is provided with grooves for guiding light during recording and reproduction using laser light, details of which are shown in FIG. FIG. 4 & is an enlarged view of the groove formed in the additional layer, and shows that the recording 1E single disc has a guide groove 10 provided in advance in a concentric solid or spiral shape: 1-? The depth is about 7 o○ people at most.

FIG. 4 is a cross-sectional view of forming grooves, in which a metal film 11 for optical recording is deposited on the surface of the grooves 10 provided at a predetermined pitch.
1'1. Therefore, when recording and reproducing using a laser beam, this groove is used as a reference, and in the case of concentric solid grooves, irregularities corresponding to the address signal are provided in the matching grooves. By accessing the address, you can freely record and play back anywhere you want. The recording method here is to create optical shading on the optical recording layer by irradiation with laser light, and when there is no groove for light guide, C1, and when recording is resumed after being interrupted once, This method has the disadvantage that it tends to waste space at the interrupted part.

Furthermore, the substrate is made of an organic polymer material S1, and a material with good thickness accuracy is manufactured as a base material.1. Informed,
There is a problem in that the higher the precision required, the higher the cost. However, if a new additional layer is provided as in this example, it is possible to control the overall thickness even if there are variations in the thickness of the substrate itself, and at the same time, it is possible to balance the mechanical strength and rotation. It is also possible to take

- If a photocurable resin is used as the material for the dl and additional layers when forming the grooves, it can be easily produced and mass-produced by performing ffl type press transfer and simultaneously photocuring. ing. Photocurable resins have the advantage of being easy to use and have low shrinkage during curing, but when considering the overall strength of the disc base material including the reinforcement layer, There is no problem in using a thermosetting resin, such as an epoxy resin, as long as it is of the same quality as the layer on the substrate.

Also, when bonding two discs together, if a photo-curable adhesive is used as the adhesive, the above-mentioned 10.

On the other hand, it is necessary that not only the disk profit on the recording layer side but also the disk profit on the protection side be transparent. Therefore, when using an opaque material, it is necessary to use an epoxy resin, etc., but if the two disk base materials are mechanically balanced and have the same physical constants such as water absorption rate and coefficient of thermal expansion, and the same moisture absorption state. Even if these adhesives are used, there is no particular effect on shape changes such as warping and distortion after assembly.

In the embodiment, there is no problem even if the two disk substrates are bonded over the entire surface thereof, or if only the parts excluding the optical recording area are bonded locally. In this case, both recording and reproducing are possible using a method in which the optical recording layer is irradiated with laser light to form optical shading or unevenness. Of course, the same thing can be said in the case of only playback where .

However, if two disc base materials are to be fully laminated,
However, as an optical recording method, it is limited to providing optical shading on the optical recording layer, and it is impossible to use a method that creates unevenness on the optical recording layer.3. 7 and 41, the light absorption coefficient or the refractive index is required to change when irradiated with laser light,
An example of this is Deru's low oxide TaOx (o (x
There are some products that have a thin film containing (2,0) as a 1: component. - If such a recording layer is provided, and the two disc substrates are to be bonded together on their entire surface, it is best to use an adhesive as an adhesive. Should you use, for example W:? In the case of a hardening type adhesive, a diyfi agent of polyvinyl alcohol is preferred.

The information recording carrier having the structure as in the first embodiment is particularly effective for lifting platforms whose old quality is if polymeric polymer or 1゛). KI, acrylic resin (polymethacrylic acid methacrylic acid methacrylic acid methacrylic acid methacrylic acid methacrylic acid methacrylic acid methacrylic acid methacrylic acid methacrylate-l-), polycarbonate 1. When using a base (1) or a platform that does not require a groove for light guidance, a configuration as shown in Figure 5 can be considered without providing an additional layer on the board. 1.- in the figure, the first substrate 6
A direct optical recording layer 7 is provided on the second substrate 6'.
and are joined by an adhesive 8. In this case as well, since the influence of the optical recording layer is small, the mechanical strengths of the two disk bases are equal and can be considered symmetrical about the adhesive layer. Of course, there is no problem in making the overall strength of the second substrate equal, including that of the optical recording layer. In addition, in the first embodiment, the optical recording layer is one piece 1r.
ri only, and the additional layer on the protective layer side is used to regulate the thickness and balance the mechanical strength, and the formation of the groove itself is not an essential condition. The second embodiment will be explained with reference to the drawings. In Figure 6-
1, an optical recording layer 7 is deposited on the surface of the additional layer 6 provided on the first substrate 5. The second disk group, (
12 is a base 4A or C-) having a different thickness from that of the first substrate 6, and is bonded to the adhesive 8. This is equivalent to the overall mechanical strength of the first substrate including the optical recording layer, and has the same effect on changes in shape over time after assembly.

Next, a third embodiment of the present invention will be described with reference to FIG.

The two substrates 6, 5' provided with the photocurable resin 1) 4, the additional layers 6, 61 and the optical recording layers 7, 7' are bonded to the adhesive 8. There is. In this case, the recording layer 7,7J
r], opaque, as in the first embodiment, the adhesive 8 is hardened, + In addition, the two substrates are mechanically and geometrically completely symmetrical with respect to the adhesive layer, so even under special environments they will not suffer from deformation over time such as warping or distortion. Kawato is rarely a problem.

In this embodiment, there is no particular necessity regarding the presence or absence of the formation of grooves for light guiding or the presence or absence of additional layers, as long as the two substrates have symmetrical structures. The same things as in the first embodiment can be said about the additive layer and the quality of the disk base material in the second and third embodiments.

As described in 1-1 below, the present invention has a simple structure and can be used not only under normal usage environments but also under special conditions such as high temperature and high humidity. This makes it possible to obtain an information recording carrier with little change in shape, low cost, high shape stability, and excellent strength, and at the same time, it has a great effect in improving the yield during manufacturing.

[Brief explanation of the drawing]

Figure 1a is a sectional view of an information recording JtB body on which a synthetic resin sheet is pasted as a conventional protective layer; Figure 1a is a sectional view of an information recording carrier coated with an organic polymer as a conventional protective layer;
FIG. 2 is a cross-sectional view of an information recording carrier in which two conventional record carriers are combined with a 11111tl protective layer, FIG. 3 is a cross-sectional view of an information recording carrier showing the first embodiment of the present invention, and FIG. 4a 4 is an enlarged plan view of the forming groove, FIG. 4 is an enlarged cross-sectional view of the forming groove, and FIG. 6 is a cross-section of an information recording carrier showing an example of a structure without an additional layer in the first embodiment of the present invention. 6 is a cross-sectional view of an information recording medium according to a second embodiment of the present invention, and FIG. 7 is a cross-sectional view of an information recording medium according to a third embodiment of the present invention. be. ) 5.5'... Substrate, 6.6'... A.1 additional layer, End... Recording layer, 8... Adhesive. Name of agent Attorney 1: Satoshi Nakao 1) 3 and 1 other person Figure 1/Z ((l)
3 2 (b. Figure 2 2' / 2 / Figure 3 5. / / ;g □ Figure 1 ÷ Figure 1 Figure 5 5' 7 Figure 6 / 2 Figure 7 + c'ge

Claims (1)

[Claims] (1) Two base materials having an information recording layer on at least one of the base materials are joined with the information recording layer inside, and the two base materials are subjected to environmental changes. (2) Claim 1 characterized in that the two base materials have the same mechanical strength.
14 records of 1,111 records listed in Section 1. (3) The information recording body 111 according to claim 1, characterized in that the water absorption rates of the two base materials are equal. (4) The information recording carrier according to claim 1, wherein the two base materials have equal coefficients of thermal expansion.