JPH07182696A - Optical recording medium - Google Patents

Abstract

PURPOSE:To make pit lengths uniform to a specified value, and to obtain an optical recording medium having excellent recording characteristics and high environmental stability by recording so as to form a rim part at a recording position after irradiated with a recording laser light. CONSTITUTION:An optical recording medium has a transparent board 1, a recording layer 2, and a metal layer 3. Recording is conducted so as to form a rim part 7 at a recording position. The part 7 clarifies a boundary between a recording pit part 6 and a land part in a group 5. A protrusion formed around the pit is provided. The part 7 is set, for example, to a width in which the width of the rim can be actually recognized such as 1nm to 250nm and the height is 1nm to 250nm. As a result, recording information can be accurately read on a various player having pick-ups in which oscillating laser wavelengths, optical characteristics and optical quantity are delicately different.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical recording medium, and more particularly to an optical recording medium capable of recording a large amount of information.

[0002]

2. Description of the Related Art In recent years, an additionally recordable optical recording medium has attracted attention for the purpose of recording and storing music, images, data, programs and the like. Among them, an optical recording medium (CD-W) capable of recording and reproducing with a commercially available compact disc player is used.
O) is receiving attention. Among such recordable optical recording media, an optical recording medium having a dye as a recording layer can form a recording film by spin coating or the like, and an optical recording medium having an inorganic thin film as a recording film that requires a vacuum technique. It is superior in productivity, economic efficiency, yield, etc., and has already been put to practical use.

[0003]

In an additionally recordable optical recording medium having a dye as a recording layer, record information is generally recorded by changing several kinds of pit lengths. When such a recording method is performed, it is necessary to secure a sufficient modulation degree, which is the contrast between the recording pits and the pits, and to record so that the pit length of each type conforms to its specified value. In addition, it is one of the important characteristics for improving the recording / reproducing characteristics.

Further, the record information thus recorded must be recorded so that it can be correctly reproduced by any CD player. Furthermore, the optical recording medium in which the pits thus recorded are not changed by the laser light for reproducing the recorded information or are not changed under the environment of storage (deterioration due to sunlight, deterioration due to high temperature, high humidity, etc.) It is also one of the important issues to fabricate.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies to achieve the above object, and as a result, the above object was achieved by forming a rim portion at a recording portion after irradiation with a recording laser beam. As a result, they have completed the present invention. That is, the present invention provides an optical recording medium having a recording layer containing at least an organic dye and a metal layer provided directly on the recording layer on a transparent substrate, and recording after irradiation with a recording laser beam. The optical recording medium is characterized in that recording is performed so that a rim portion is formed at a portion, and preferably, the width of the rim portion at the recording portion is 250 nm or less. A medium, and more preferably, an optical recording medium characterized in that the height of the rim portion of the recording portion is 250 nm or less.

As shown in FIG. 1, the structure of the optical recording medium of the present invention is composed of a transparent substrate 1, a recording layer 2 and a metal layer 3, which may be formed on the metal layer or the transparent substrate as needed for the purpose of improving the characteristics. A protective layer may be provided underneath or a base layer or the like may be provided between the transparent substrate and the recording layer. The transparent substrate used in the present invention must be one that transmits light for recording and reading signals. It is desirable that the light transmittance is 85% or more and the optical anisotropy is small. A preferable example is a substrate using a thermoplastic resin such as an acrylic resin, a polycarbonate resin, a polyamide resin, a vinyl chloride resin, or a polyolefin resin. Among these the mechanical strength of the substrate,
An injection-molded resin substrate of an acrylic resin, a polycarbonate resin, or a polyolefin resin is preferable, and a polycarbonate resin substrate is particularly preferable, from the viewpoints of easy provision of a guide groove, a reproduction-only signal, and the like, and economy.

The shape of these substrates may be plate-like, film-like, circular or card-like. Of course, the surface of the substrate may have a guide groove for indicating a recording position, a pit for indicating a recording position, and a pit for partially reproducing only information. Such guide grooves, pits, etc. are preferably provided when the substrate is made by injection molding or casting, but can also be provided by applying an ultraviolet curable resin on the substrate and superimposing it on a stamper for ultraviolet exposure. .

The recording layer used in the present invention is mainly composed of an organic dye, and specific examples thereof include macrocyclic azaannulene dyes (phthalocyanine dyes, naphthalocyanine dyes, porphyrin dyes, etc.), polymethine dyes (cyanine dyes). , Merocyanine dyes, styryl dyes, squarylium dyes, etc.), anthraquinone dyes, azurenium dyes, azo dyes and the like. Of these, phthalocyanine dyes and cyanine dyes are preferable. The content of the organic dye in the recording layer used in the present invention is 30% or more, preferably 60% or more. The dye used is not limited to a single dye, but may be a mixture of a plurality of dyes. Also,
It may be composed of two or more dye layers. Further, in order to improve recording characteristics when producing the recording layer, further substituted phthalocyanine, substituted naphthalocyanine, substituted porphyrin dye, cyanine dye, dithiol metal complex,
Other organic dyes such as anthraquinone dye, resins such as nitrocellulose, ethyl cellulose, acrylic resin, polystyrene resin, urethane resin and leveling agents, defoaming agents and the like may be used in combination within a range that does not impair the effects of the present invention. .

The recording layer can be usually formed by means of spin coating, dip coating, spray coating, roll coating, vapor deposition or the like, but the spin coating method is preferred from the viewpoint of ease of film formation. A solvent that does not damage the substrate when the dye is formed by spin coating, for example, hexane, heptane, octane, decane, cyclohexane, methylcyclohexane and other aliphatic or alicyclic hydrocarbons, diethyl ether, dibutyl ether,
The dye may be dissolved in a non-polar solvent such as an ether-based solvent such as diisopropyl ether or a polar solvent such as an alcohol-based polar solvent such as methyl alcohol, ethyl alcohol, isopropyl alcohol, allyl alcohol, or methyl cellosolve and coated. In the present invention, the thickness of the recording layer containing the dye is usually 30 to 500 nm and 50 to 250 n.
m is more preferred.

As a material of the metal layer used in the present invention, a metal such as Au, Al, Ag, Pt, Ni, Cu, a metal alloy, a metal compound, or the like is used. As a method for producing the metal layer, vapor deposition, sputtering, ion plating, spin coating, spray coating or the like is used. Further, a protective layer may be provided on the metal layer in order to protect the recording layer and the metal layer. As the material of the protective layer, acrylic resin, polycarbonate resin, ultraviolet curable resin, electron beam curable resin, polysiloxane resin and the like are used.
Further, a base layer may be provided between the substrate and the recording layer in order to improve the adhesion and durability between the substrate and the recording layer, and various layers may be provided as necessary.

The optical recording medium of the present invention must be such that recording is performed so that a rim portion is formed at the recording portion. The rim portion of the recording portion in the present invention is shown in FIG.
As shown in FIG. 3, a raised portion provided around the pit, which clearly shows the boundary between the recording pit portion 6 in the groove 5 and the land portion, is indicated. In the present invention, basically, the rim portion is formed at the time of recording, but more preferably, the rim portion 7 is preferably formed with an appropriate width and height. If the width of the rim portion is too narrow, the effect due to the formation of the rim portion does not appear, and if it is too wide, crosstalk becomes large, which causes an error. Also, if the height of the rim portion is too low, the effect of forming the rim portion does not appear, and if it is too high, stress is applied to the metal layer in contact with the recording layer, and a gap is formed at the interface between the recording layer and the metal layer. It tends to occur and causes an error. For the above reasons, it is preferable to control the rim portion to have a width at which the width of the rim can be actually confirmed, for example, a width of 1 nm to 250 nm and a height of 1 nm to 250 nm. More preferably, the width is 2 nm or more and 150 n
It is desirable to control the height to 1 m or less and the height to 1 nm to 150 nm.

There are various methods for forming the rim portion, and the method is not particularly limited. For example, when a pit is formed by irradiation with a recording laser beam, the substrate around the pit is heated to a glass transition point or higher due to heat generation of the recording dye layer, and it is a simple method to use a phenomenon in which the substrate rises together with the recording dye layer. Is. Good recording characteristics can be obtained by controlling the manner of rising. Specific examples include controlling the film thickness of the recording dye layer, controlling the intensity of laser light, changing the type of dye, and controlling the amount of heat generated in the recording dye layer. To be In this case, increase the thickness of the recording dye layer,
When the intensity of the laser light is increased, the amount of heat generated is increased and the width and height of the rim portion are increased. Further, the formation of the rim portion can be controlled by changing the material of the substrate. For example, by making the substrate hard, the substrate is less likely to be deformed and the rim portion is less likely to be formed.

In this way, the present invention is basically characterized in that writing is performed so as to form a rim portion, and a pit portion in a groove is formed by the rim portion thus formed. The boundary of the land portion becomes clear, the modulation degree increases, and it becomes easy to control various recording pit lengths so as to conform to the specified value. That is, by clarifying the pit portion and the land portion in the groove, the recorded information can be accurately read out even on various players having pickups with slightly different oscillation laser wavelength, optical characteristics, light amount, and the like. is there. Further, the dye used in the recording layer of the present optical recording medium is basically a dye that is extremely stable against a reproduction laser beam or under various environments, but in the unlikely event that the dye deteriorates. Even in a situation, since the rim portion is formed in the pit portion, the recorded information can be read out without changing.

[0014]

EXAMPLES The present invention will be specifically described below with reference to examples, but the embodiments of the present invention are not limited thereto. [Example 1] A center portion of a surface having a guide groove of an injection-molded polycarbonate resin substrate having a spiral guide groove (depth 150 nm, width 0.5 μm, pitch 1.6 μm) having a thickness of 1.2 mm and a diameter of 120 nm. 20% by weight of the phthalocyanine dye having one tertiary amyl group on each of the four benzene rings in the phthalocyanine molecule, Pd as the central metal, and two bromine atoms as the whole phthalocyanine molecule. After the octane solution of 1 was dropped, the resin substrate was rotated at a speed of 1000 rpm for 10 seconds and dried at 70 ° C. for 1 hour. By this operation, a recording layer of phthalocyanine dye was formed on the resin substrate.
The film thickness of this recording layer was 100 nm. An 80 nm-thick gold reflective film was formed as a coating layer on the recording layer by a sputtering method, and further an ultraviolet curable resin (manufactured by Dainippon Ink and Chemicals, Inc.) was spin-coated on the gold reflective film. After applying Dicure Clear SD-17), ultraviolet rays were radiated to form a protective layer having a thickness of 7 μm to prepare a medium.

This optical recording medium is placed on a turntable,
While rotating at a linear velocity of 1.4 m / s, a drive having an optical head equipped with a semiconductor laser having an oscillation wavelength of 785 nm was used to control the laser beam to focus on the recording layer on the guide groove through the resin substrate. On the recording surface, however, an EFM modulated signal was recorded with a laser output of 4 to 10 mW in the same manner as used for compact discs. Next, using the same device, the output of the semiconductor laser was set to 0.7 mW on the recording surface, and the recorded signal was read. The best error rate and jitter are obtained when the recording laser power is 7.5 mW, the block error rate (BLER) is <5, and the 3T modulation is 0.4.
5, 11T modulation degree is 0.71, pit jitter is 25
ns, deviation from the specified value of 3T pit is 30 ns, 11
The deviation of the T pit from the specified value was -45 ns, and extremely good recording and reproduction could be performed. In the present invention,
The block error rate (BLER) is the number of C1 errors that occur per second, and the deviation from the specified value of each pit is the value measured by a time interval analyzer.
When this medium was reproduced with a commercially available CD player, it could be reproduced extremely well. The protective layer and the reflective layer of this medium were carefully peeled off to expose the recording layer, gold was sputtered on the recording layer, and STM observation of the recording portion was performed.
It was found that a rim portion having a width of 50 nm and a height of 40 nm was formed in the recording pit portion. In addition, this medium is
After leaving it in a thermo-hygrostat at ℃ and 80% RH for 500 hours,
When the reproducing characteristics were measured, BLER was <5, 3T modulation was 0.45, 11T modulation was 0.71, pit jitter was 25 ns, and deviation from the specified value of 3T pit was 30 n.
The deviation from the specified value for s and 11T pits is -45 ns,
No deterioration was observed. It could be played back on a commercial CD player without any problems.

[Comparative Example 1-1] Recording and reproduction were carried out in the same manner as in Example 1 except that the optical recording medium produced under the same conditions as in Example 1 had a recording laser power of 10.0 mW. At this time, BLER is 250, 3T modulation degree is 0.55, 11
T modulation is 0.75, pit jitter is 36ns, 3T
The deviation from the specified value of the pit was 45 ns, and the deviation from the specified value of the 11T pit was -85 ns. When this medium was played on a commercially available CD player, some audio clicks occurred. From STM observation of the recording layer of this medium, it was found that a rim portion having a width of 250 nm and a height of 270 nm was formed in the recording pit portion. Further, when this medium was left in the constant temperature and humidity chamber of Example 1 for 500 hours,
Part of the reflective layer is peeled off, the deviation from the specified value of 3T pit is 40 ns, and the deviation from the specified value of 11T pit is −
It wasn't about 75 ns, but BLER was 550, 3T
The modulation degree was 0.57, the 11T modulation degree was 0.77, and the pit jitter was 40 ns, and the signal characteristics were deteriorated. A large number of audio clicks occurred when playing on a commercial CD player.

[Comparative Example 1-2] The coating conditions of the dye solution were set to 6
An optical recording medium was produced by performing the same operations as in Example 1 except that the speed was changed to 00 rpm. The thickness of the recording layer of this medium was 200 nm. When this optical recording medium was placed on a turntable and the recording characteristics were evaluated in the same manner as in Example 1, the best BL was obtained when the recording laser power was 6.5 mW.
ER and jitter were obtained, but BLER was 200, 3
The T modulation degree is 0.56, the 11T modulation degree is 0.77, the pit jitter is 36 ns, the deviation from the specified value of the 3T pit is 45 ns, and the deviation from the specified value of the 11T pit is -72.
It became worse with ns. When this medium was played on a commercially available CD player, some audio clicks occurred. From the STM observation of the recording layer of this medium, the width of the recording pit was 30
It was found that a rim portion having a thickness of 0 nm and a height of 200 nm was formed. Also, after the medium was left for 500 hours in the constant temperature and humidity chamber of Example 1, the reproduction characteristics were measured.
The LER is 180, the 3T modulation is 0.58, the 11T modulation is 0.78, the pit jitter is 38 ns, the deviation from the specified value of the 3T pit is 60 ns, and the deviation from the specified value of the 11T pit is -90 ns. No deterioration in characteristics was observed. Similarly, an audio click occurred on a commercial CD player.

[Example 2] An optical recording medium (recording layer film thickness 100 nm) manufactured by the same method as in Example 1 was used except that a 2P (acrylic-ultraviolet curing resin) substrate was used as the substrate. It was recorded and reproduced by the method. Optimal recording power is 7.5mW, BLER is 10, 3T modulation is 0.3
6, 11T modulation degree is 0.65, pit jitter is 25n
Deviation from the standard value of s, 3T pit is 10ns, 11T
The deviation from the specified value of the pit was -30 ns, and good signal characteristics were obtained. From STM observation of the recording layer of this medium, it was found that a rim portion having a width of 20 nm and a height of 10 nm was formed in the recording pit portion. In addition, this medium is used in Example 1.
When left in the constant temperature and humidity chamber for 500 hours, the BLER was 10, 3T modulation was 0.36, and 11T modulation was 0.6.
5, the pit jitter was 25 ns, the deviation from the specified value of the 3T pit was 10 ns, and the deviation from the specified value of the 11T pit was -30 ns, showing no change in the signal characteristics.

[Comparative Example 2] An optical recording medium (recording layer thickness 100 nm) manufactured by the same method as in Example 1 except that a glass substrate was used as the substrate was recorded and reproduced by the same method as in Example 1. . The optimum recording power is 9mW and BLE at that time
R is 15, 3T modulation is 0.30, 11T modulation is 0.
62, the pit jitter was 30 ns, the deviation from the specified value of the 3T pit was 15 ns, and the deviation from the specified value of the 11T pit was -40 ns. From the STM observation of the recording layer of this medium, it was found that the rim portion was not formed in the recording pit portion. Further, when this medium was left in the constant temperature and humidity chamber of Example 1 for 500 hours, partial peeling occurred in the reflective layer, and BLER was 650, 3T modulation was 0.30, and 11T.
The modulation degree was 0.60, the pit jitter was 42 ns, the deviation from the specified value of the 3T pit was 25 ns, and the deviation from the specified value of the 11T pit was -50 ns, and the signal characteristics were deteriorated. A large number of audio clicks occurred when playing on a commercial CD player.

[Embodiment 3] 1-Ethyl-3,3-dimethyl-2- {5- (1-ethyl) at the center of the surface having the guide groove of the same injection-molded resin substrate used in Embodiment 1. −
3,3-Dimethyl-2-indolinylidene) -1,3-
Pentadienyl} -3H-indolium After adding dropwise a 30% by weight solution of perchlorate in ethyl cellosolve,
This resin substrate was rotated at a speed of 1000 rpm for 10 seconds and dried at 70 ° C. for 1 hour to form a recording layer of a cyanine dye on the resin substrate. The film thickness of this recording layer was 220 nm. An 80 nm-thick gold reflective film was formed as a coating layer on the recording layer by a sputtering method, and further an ultraviolet curable resin (manufactured by Dainippon Ink and Chemicals, Inc.) was spin-coated on the gold reflective film. After applying Dicure Clear SD-17), irradiate with ultraviolet rays to 7 μm
A protective layer of was formed into a medium to prepare a medium.

Place this optical recording medium on a turntable,
When the recording characteristics were evaluated by the same method as in Example 1, the best BLER and jitter were obtained when the recording laser power was 7 mW, the block error rate was 10, 3T modulation was 0.38, and 11T modulation was 0. .68, the pit jitter is 28 ns, and the deviation from the specified value for the 3T pit is 10
The deviation from the specified value for ns and 11T pits was -30 ns, and good recording and reproduction could be performed. This medium is a commercial CD
When played back on a player, good playback was possible. STM observation of this medium revealed that a rim portion having a width of 10 nm and a height of 10 nm was formed in the recording pit portion. Further, when this medium was left in the constant temperature and humidity chamber of Example 1 for 500 hours, discoloration of the recording layer was observed, and it was found that the recording dye was damaged. However, the reproduction characteristics of the medium are as follows: BLER is 40, 3T modulation is 0.32, 11T modulation is 0.60, pit jitter is 34 ns, and deviation from the specified value of 3T pit is 10 ns.
The deviation from the specified value of 11T pit is -40 ns,
Although it was somewhat deteriorated, it could be played back on a commercial CD player without any problem.

[Comparative Example 3-1] The coating condition of the dye solution was 2
An optical recording medium was produced by performing the same operations as in Example 3 except that the speed was changed to 000 rpm. The thickness of the recording layer of this medium was 100 nm. When this optical recording medium was placed on a turntable and the recording characteristics were evaluated in the same manner as in Example 1, the best BLE was obtained when the recording laser power was 9 mW.
R and jitter were obtained, BLER was 200, 3T modulation was 0.34, 11T modulation was 0.60, pit jitter was 40 ns, and deviation from the specified value of 3T pit was -35.
The deviation from the specified value of ns and 11T pit was -55 ns. When this medium was played on a commercially available CD player, an audio click occurred partially. From STM observation of the recording layer of this medium, it was found that almost no rim portion was formed in the recording pit portion. When this medium was left in the constant temperature and humidity chamber of Example 1 for 500 hours, discoloration of the recording layer was observed and it was found that the recording dye was damaged. The reproduction characteristics of this medium are
> 1000, the degree of 3T modulation was 0.27, the degree of 11T modulation was 0.45, and the pit jitter was 57 ns, showing significant deterioration. It could not be played on a commercial CD player.

[Comparative Example 3-2] 2P of Example 2 was applied to the substrate.
An optical recording medium (recording layer thickness 220n) manufactured in the same manner as in Example 3 except that a (acrylic-ultraviolet curable resin) substrate was used.
The recording characteristics of m) were evaluated in the same manner as in Example 1. The best BLER and jitter were obtained when the recording laser power was 7.5 mW. The BLER was 200, the 3T modulation was 0.32, the 11T modulation was 0.60, and the pit jitter was 38 ns from the specified value of the 3T pit. Deviation is -41n
The deviation of the s and 11T pits from the specified value was -50 ns. From STM observation of the recording layer of this medium, it was found that almost no rim portion was formed in the recording pit portion. When this medium was left in the constant temperature and humidity chamber of Example 1 for 500 hours, discoloration of the recording layer was observed and it was found that the recording dye was damaged. The reproduction characteristics of this medium are as follows: BLER> 1000, 3T modulation degree 0.22,
11T modulation is 0.40, pit jitter is> 60ns
And significant deterioration was observed.

[0024]

According to the present invention, as is clear from the examples, the rim portion is formed at the recording portion after the irradiation of the recording laser beam, so that the pit length is adjusted to the specified value. An optical recording medium having excellent characteristics and high environmental stability can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of the configuration of an optical recording medium.

FIG. 2 is a sectional view showing the shape of a recording pit portion.

[Explanation of symbols]

 1 substrate 2 recording layer 3 metal layer (reflection layer) 4 protective layer 5 groove 6 pit 7 rim portion

Claims (3)

[Claims] 1. An optical recording medium having, on a transparent substrate, a recording layer containing at least an organic dye and a metal layer provided in direct contact with the recording layer, a recording portion after irradiation with a recording laser beam. An optical recording medium is characterized in that recording is performed so that a rim portion is formed on the optical recording medium. 2. The optical recording medium according to claim 1, wherein the width of the rim portion of the recording portion is 250 nm or less. 3. The height of the rim portion of the recording portion is 250 nm
The optical recording medium according to claim 1 or 2, wherein: