JPH04229428A - Optical information recording medium - Google Patents

Abstract

PURPOSE:To obtain an optical card inhibiting the deterioration of the recording layer of org. coloring matter at the card return part due to light for reproduction. CONSTITUTION:When a recessed preformat composed of tracking tracks 6 in a recording region 2 and tracking tracks 6a in a non-recording region 3 and used as guide grooves for light for recording and reproduction is formed in a substrate 5 and a recording layer 4 of org. coloring matter applied with a solvent is formed on the preformat to obtain an optical card 1, the cross-sectional area of the recess 6a' of each of the tracking tracks 6a in the non- recording region 3 is made larger than that of the recess 6' of each of the tracking tracks 6 in the recording region 2.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording medium that undergoes little optical deterioration due to information reproducing light.

0002

[Background Art] In recent years, as society has become more information-oriented, information recording carriers such as optical discs, optical cards, and optical tapes that record or reproduce information optically and optical Many information recording and reproducing devices have been proposed. Binarized information is stored on the information recording carrier by changes in reflectance, changes in reflected light intensity due to changes in surface shape such as the presence or absence of pits, and changes in the plane of polarization due to magneto-optic effects. There are some methods that can be detected by converting the change into an intensity change. The characteristics of the information recording carrier mentioned above are that it has a high recording density;
Moreover, since it is possible to record and reproduce without contact, it has advantages such as a long life.

[0003] Optical card type optical information recording media (hereinafter referred to as
(referred to as optical cards) have recently been actively researched and developed, and proposals have also begun to be made.

FIG. 4 shows a conventional DRAW (direct
read after write; direct rea
FIG. 3 is a schematic plan view showing a recording format of a d after write type optical card. In Figure 4,
A recording area 2 is provided on an optical card 1 which is a record carrier, and the recording area 2 is formed by a plurality of tracks 3 arranged. Furthermore, a start bit and a stop bit are formed in the track 3, and the track 3 has an information capacity of about several thousand bits. Further, each track 3 is separated by a reference line 5 (hereinafter referred to as an R line). Note that arrow A is the direction of movement of the optical card 1 during playback.

FIG. 5 is a schematic diagram of an optical card reproducing method. In FIG. 5, the optical card 1 is movable in the direction of arrow A by a reciprocating rotation mechanism 56. Information recorded on the optical card 1 is transferred to the optical head 51 for each track 3.
is read and played by. First, light from a light source 57 such as a semiconductor laser is focused by a lens system 58,
The track 3 on which information is recorded is illuminated. The image of the illuminated track 3 is transferred to the sensor 50 by an imaging optical system 59.
An electric signal corresponding to the information recorded on the track 3 is output from the sensor 50.

When the reading of the track 3 is completed, the optical card 1 moves in the direction of arrow A or the optical head 51 moves in the direction in which the tracks 3 are arranged (in the direction of arrow C), and information on the next track 3 is read in the same manner. It will be held on.

Furthermore, in order to access any track 3 on the optical card 1, the optical head 51 is moved in the direction of arrow C. The optical head 51 selects the track 3 to which the target track 3 to be read belongs by counting the R lines 5, and stops when reaching the target track 3. Subsequently, the optical card 1 is moved in the direction of arrow A by the reciprocating rotation mechanism 56, and information on the target track 3 is read.

[0008] As described above, in the conventional information recording carrier such as the optical card 1, information is optically recorded or reproduced by the light illuminated from the light source 57 disposed in the optical head 51 of the optical recording/reproducing device. be exposed. As mentioned above, during tracking during playback of the optical card, the optical card 1 moves in the direction of the arrow A by the reciprocating rotation mechanism 56 and reads information. As a result, there are times when the optical card stops as it moves in reverse, and writing progresses very gradually due to the energy of the read light, eventually making it difficult to detect the tracking signal. It was done.

The deterioration of the recording layer of the return stationary portion of the optical card during recording and reproduction described above differs depending on the number of recording layers. In other words, in the case of a metal-based or metal oxide-based recording layer that easily diffuses the thermal energy generated by the reproduction laser beam, the deterioration of the recording layer in the return stationary part is small, but mass production is difficult because the recording layer is created by vapor deposition. There are disadvantages that are not good.

On the other hand, cyanine dyes, polymethine dyes, azulene dyes, xanthene dyes, and the like are known as solvent-coated organic dye media that are highly mass-producible. However, optical card media using organic dyes have the disadvantage that the reflectance of the above-mentioned optical card return stationary portion deteriorates rapidly due to reproduction laser light.

[0011]

SUMMARY OF THE INVENTION In order to improve the above-mentioned drawbacks, an invention has already been disclosed in which the optical card return stationary part, which is the non-recording part of the optical card, is made into an optically non-recordable part. Specific examples of these inventions include (1) Putting a large amount of light stabilizer in the area where optical recording is not possible. (Unexamined Japanese Patent Publication No. 1-19
(No. 542) ■ Provide another recording layer that is difficult to record in areas where optical recording is not possible. (Japanese Unexamined Patent Publication No. 19541/1999), but all of these have a recording part and a non-recording part (
Since the recording material of the optical card return stationary part (optical card return stationary part) is different, productivity is low.

In particular, in the case of an optical card having a solvent-coated organic dye recording layer, the boundary between the recorded area and the non-recorded area in the recording layer bleeds, causing AT (auto tracking) or AF (
Autofocus) function is prone to errors.

The present invention has been made in order to improve the above-mentioned drawbacks of the prior art, and its object is to provide an optical information recording medium that is less susceptible to optical deterioration due to information reproducing light.

[0014]

[Means for Solving the Problems] That is, the present invention provides an optical card having a concave preformat used as a guide groove for recording and reproducing light on a substrate and having a solvent-coated organic dye recording layer. The optical information recording medium is characterized in that the cross-sectional area of the concave portion of the format is larger in the non-recording area than in the recording area.

The present invention will be explained in detail below.

FIG. 1(a) is an explanatory diagram showing a general embodiment of the optical information recording medium of the present invention, and FIG. 1(b) is an explanatory diagram showing a general embodiment of the optical information recording medium of the present invention.
FIG. 1(c) is a sectional view taken along line B, and FIG. 1(c) is a sectional view taken along line DD. In the figure, the optical information recording medium of the present invention has a concave preformat on a substrate 5, which is used as a guide groove for recording and reproducing light, and includes tracking tracks 6 and 6a in a recording area 2 and a non-recording area 3, respectively. , and has a solvent-coated organic dye recording layer 4 thereon, in which the cross-sectional area of the concave portion of the concave preformat is larger than that of the concave portion 6' of the tracking track 6 in the recording area in the tracking area of the non-recording area. The concave portion 6a' of the track 6a is formed larger.

In the optical card 1 shown in FIG.
A schematic diagram of a card cross section is shown in FIG. 1(b), and a schematic diagram of a card cross section of the non-recording area 3 of the return area of the optical card in the non-recording area is shown in FIG. 1(c).

In the optical card 1, the concave portion 6 of the concave preformatted tracking track 6 shown in FIG. 1(b)
The line width L of ' is 2 to 4 μm, and is preferably 1/2 to 1 times the spot diameter of the normal reproduction laser beam. In addition, the concave portion 6
In order to obtain a high-quality tracking track signal, the depth d1 of
3500 Å is preferred. Recording track 7 in recording area 2
The film thickness d3 of the organic dye recording layer 4 is the film thickness at which the recording layer has a maximum reflectance (500 to 1000 Å) + 50 Å, -0 Å
It is preferable to form it by coating it on the surface. Therefore, the cross-sectional area of the concave preformatted tracking track 6 in the recording area is about 0.45 to 1.40 .mu.m@2.

On the other hand, in the non-recording area 3 which is a non-recording area and is a return area of the card (or reproduction laser beam), the depth d2 of the recessed part 6a' of the tracking track 6a is equal to the depth d2 of the recessed part of the recording area 2. 1 of depth d1 of 6'.
Form to 2 to 1.5 times the size. However, the line width L of the concave portion 6a' of the tracking track 6a is set to
It is preferable to make it the same as. As a result, Figure 1(c)
The cross-sectional area of the concave portion 6a' of the tracking track 6a is 1 of the cross-sectional area of the concave portion 6' of the tracking track 6.
．． 1 to 1.5 times.

[0020] By applying a solution-coated organic dye medium to the surface of the substrate having the pregrooves shown in FIGS. 1(b) and 1(c) in one step under the same conditions,
In the recording track of the recording area 2, an optimal dye film thickness can be obtained, and an organic dye recording layer that can provide sufficient sensitivity can be formed. On the other hand, in the non-recording area 3, during the drying process of the solvent, a larger amount of the organic dye solution coated on the substrate enters the recessed portion 6a' of the pregroove having a large cross-sectional area than the recessed portion 6'. As a result, the dye film thickness d4 in the reproduction laser scanning section 8 of the non-recording area scanned by the reproduction laser beam is d
It is 100 to 300 Å thinner than 3.

Generally, the recording sensitivity of an organic dye recording layer increases as the amount of light absorbed by the recording layer increases. In other words, it is known that the thicker the recording layer is, the larger it is. However, the reflectance value of the recording layer falls within ±10% of the central value at around ±200 Å from the film thickness at which the reflectance reaches its maximum, and the value of the reflectance of the recording layer falls within ±10% of the central value.
F) Not enough to cause a functional error.

[0022] Therefore, in the non-recording area, the film thickness becomes thinner, and the decrease in reflectance is within -10% of that in the recording area, but the recording sensitivity decreases to 0.7 to 0.5. As a result, optical deterioration of the card return area, which is a non-recording area, is suppressed. Next, the present invention will be explained in detail by showing an example using a dye having the structural formula (I) shown below.

[0023]

embedded image FIG. 2 is a graph showing the correlation between the thickness of the dye film represented by the structural formula (I) of Chemical Formula 1, the reflectance of the recording layer, and the recording sensitivity.

Recording sensitivity is determined at a dye film thickness of 9 where the reflectance is maximum.
The sensitivity of each film thickness is shown relative to 50 Å as 1. In Fig. 1(b), L = 2.5 μm, d1 = 2
The dye layer was coated on the recording area 2 and non-recording area 3 of the optical card so that d3 = 1000 Å. The reflectance is 15.7%. In this case, in the non-recording area 3 which is the return area of the laser head in the non-recording area shown in FIG. 1(c), the depth of the pregroove was set to 3700 Å. L is constant at 2.5 μm.

As a result, the thickness of the dye layer in the reproduction laser beam scanning section 8 is 800 Å to 750 Å. Reflectance is 1
5.0 to 15.4%, which is sufficient for laser head AT (
It can be confirmed that the auto tracking) and AF (auto focus) functions are working. However, since the film thickness at the reproduction laser beam scanning section 8 is 800 to 750 Å,
The sensitivity of the recording layer in the non-recording area is 0.65-0.
50 times, and the optical deterioration speed during recording and reproduction of the non-recording area 3, which is the return part of the optical bed, is improved to about 1/2.

The substrate 5 used in the present invention is made of PV
C, polymethyl methacrylate, polycarbonate,
A transparent plastic plate made of polysulfone, polyolefin resin, etc. can be used. Particularly preferred is polymethyl methacrylate, which has no optical birefringence and is hard and scratch-resistant. Preferably, the substrate is an optically transparent material.

Examples of organic dye substances used in the organic dye recording layer 4 include anthraquinone derivatives (particularly those having an indathrene skeleton), dioxazine compounds and their derivatives, triphenodithiazine compounds, phenanthrene derivatives, cyanine compounds, and merocyanine. compounds, pyrylium compounds, xanthene compounds, triphenylmethane compounds, croconium dyes, azo dyes, crocones, azines, indigoids, polymethine dyes, azulene dyes, squalium dyes, and the like.

These organic dye recording layers may contain a stabilizer (quencher) such as an infrared absorber for the purpose of improving light resistance. The thickness of the recording layer is
Although a range of 400 to 1200 Å is preferable, the film thickness is usually set to a value that maximizes the reflectance based on the correlation between film thickness and reflectance. As the stabilizer, one having a skeleton shown in Chemical Formula 2 below can be used.

[0029]

embedded image In addition, in the skeletons of formulas (1) and (2) above, a substance in which the substituent for N; R has a methoxy group, a propenyl group, or a cyclocyclic group can also be used. Further, metal complexes represented by formulas (3) to (7) of Chemical Formula 3 below can be used.

[0030]

[Chemical formula 3] (However, R1 to R4 may be the same or different and each represents a substituted or unsubstituted alkyl group, aryl group, or amino group, and R5 to R8 may be the same or different, respectively. represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, or an amino group, M is Ni, Co, Mn, Cu, P
d and Pt).

Furthermore, when providing a recording layer on a substrate having a concave preformat by wet coating, a solution or dispersion of an organic dye material is applied by roll coating, Meyer bar coating, air knife coating, calendar coating, dip coating, Apply by spin coating, gravure coating, spraying, etc.

Next, depending on the type of use, the transparent substrate coated with the recording layer is laminated with a protective member via an adhesive. In the present invention, the adhesive layer includes conventionally known adhesives, such as vinyl acetate, acrylic ester, vinyl chloride, polymers and copolymers of vinyl monomers such as ethylene, acrylic acid, and acrylamide, polyamide, polyester, and epoxy. thermoplastic adhesives, such as
Adhesives such as amino resins (urea resin, melanin resin), phenol resins, epoxy resins, urethane resins, thermosetting vinyl resins, rubber adhesives such as natural rubber, nitrile rubber, chloro rubber, silicone rubber, etc. are used. . In particular, the hot melt type is a dry process,
This is preferable when considering mass and continuous production.

The protective member needs to be transparent if it is a transmission type reading system, and the requirements for birefringence are similar to those for the substrate, so the material of the protective member is limited by itself. If it is a reflective reading method, the protective member may be opaque;
The material can be selected from a wide range of materials. This protective member may be laminated directly onto the recording layer in optically close contact with the recording layer. Alternatively, a so-called air gap type configuration may be used in which a protective member is provided via an air layer if necessary.

[0034]

[Examples] The present invention will be explained in more detail below with reference to Examples. Example 1 Substrates with pregroove tracking tracks having different cross-sectional areas as shown in FIGS. 1(b) and 1(c) and optical card media using these substrates were prepared using a casting mold shown in FIG. It was created as follows.

The line width L of the pre-groove tracking track is 2.3 μm, the pitch is 12 μm, and the depth of the concave portion in the recording area of the pre-groove tracking track is 28 μm.
00 Å, and the depth of the concave portion of the pre-groove tracking track in the non-recording area of the pre-groove is 37 Å.
The pattern of the chromium deposited part 32 of the casting mold 31 shown in FIG. 3(a) and the film thickness of the chromium deposited part 33 shown in FIG. 3(b) are controlled so that the thickness is 00 Å. I got the mold. Using this casting mold, a 0.4 mm thick pregrooved substrate made of polymethyl methacrylate was obtained by casting. When the cross-sectional shape of the substrate was examined using a SEM (scanning electron microscope: Hitachi, S-820), it was found that
A substrate on which pregroove tracking tracks as shown in FIG. 1 were formed was obtained. L=2.3 μ, d1
=2750~2800Å, d2 =3650~3700
It became Å. The angle θ was approximately 60°.

Using this substrate, the following structural formula (I
) was dissolved in diacetone alcohol to a concentration of 3 wt %, applied to the pregroove surface of the substrate by gravure coating, and the solvent was dried to form an organic dye recording layer 4. Figure 1(b),(c)
The film thickness d of the recording layer of the recording section 7 and the reproduction laser scanning section 8
3, and d4 are d3 = 1000 Å, d4 =
The thickness was 800 Å.

[0037]

[Chemical formula 4] A hot melt type ethylene-vinyl acetate copolymer adhesive is applied onto the organic dye recording layer to a thickness of 0.3
A backing material made of PMMA with a thickness of mm was glued and cut into a card size using a hollow blade cutting machine to obtain an optical card type optical information recording medium.

When the reflectance of the obtained optical card type optical information recording medium was measured using a semiconductor laser beam having a wavelength of 830 nm, a laser power of 0.5 mW, and a beam diameter of 3 μm, the reflectance of the recording section 7 was 15.4. %, and it was 15.0% in the reproduction laser scanning section 8 of the non-recording area. The sensitivity of the non-recorded area was 0.60 times that of the recorded area.

Example 2 Into a diacetone alcohol solution of the polymethine dye of Example 1, the following structural formula (II
) was added, and an optical card medium was obtained in the same manner as in Example 1. Recording section 7 of the obtained optical card medium
The reflectance is 14.4%, and 14.0 in the non-recorded area
%Met. When the optical deterioration rate of the reproducing laser scanning section 8 in the non-recording area was measured by continuously irradiating the reproducing laser beam in a stationary state, it was found to be improved to 0.55 times that of the recording section 7 of Example 2.

[0040]

[C5]

[0041]

As explained above, according to the present invention, the organic material used in the recording layer can be used without disposing conventionally known different materials in the card return (laser head return) area of the non-recording area of the optical card. By using the same material as the dye medium, the reproduction light degradation of the card return area of the non-recording area of the optical card can be improved to 2/3 to 1/2.

Furthermore, the present invention provides a coated organic dye recording layer that improves the productivity of optical cards compared to the conventional one and suppresses the deterioration of the organic dye layer in the card return area, which is unique to optical cards, due to reproduction light. The used optical card medium is obtained.

[Brief explanation of the drawing]

FIG. 1 shows an example of an optical information recording medium of the present invention,
FIG. 1(a) is an explanatory diagram showing a general embodiment of the optical information recording medium of the present invention, FIG. 1(b) is a sectional view taken along the BB line, and FIG. 1(c) is a sectional view taken along the DD line.

FIG. 2 is a graph showing the correlation between the thickness of the organic dye film, the reflectance of the recording layer, and the recording sensitivity.

FIG. 3 is an explanatory diagram showing a glass mold for pouring used in Example 1 of the present invention.

FIG. 4 is a schematic plan view showing a recording format of an optical card in a conventional example.

FIG. 5 is a schematic diagram of a conventional optical card recording and reproducing method.

[Explanation of symbols] 1. Optical card 2 Recording area 3 Non-recording area 4 Organic dye recording layer 5　Substrate 6, 6a Tracking track 6', 6a' concave part 7 Recording Department 8 Reproduction laser scanning section 31, 31' Casting mold 32, 33 Chromium vapor deposited part

Claims (1)

[Claims] 1. An optical card type optical information recording medium having a concave preformat used as a guide groove for recording and reproducing light on a substrate and having a solvent-coated organic dye recording layer, wherein the concave portion of the concave preformat is The cross-sectional area of
An optical information recording medium characterized in that a non-recording area is larger than a recording area.