JPH0562192A - Method of recording optical information recording medium - Google Patents

Abstract

PURPOSE:To obtain a recording pit whose optical stability is good. CONSTITUTION:A recording operation is executed to an optical information recording medium 3 provided with an organic pigment recording layer 4 which contains an optical stabilizer 5 while the organic pigment recording layer 4 is irradiated with two beams of light which are emitted from the following: a light source 11 provided with a wavelength near the maximum absorption wavelength (lambdamax) of an organic pigment; and a light source 12 provided with a wavelength near the lambdamax of the optical stabilizer. It is promoted by means of the respective beams of light that the organic pigment and the optical stabilizer are decomposed optically and pyrolyzed, and recording pits whose optical stability are good can be formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording method for an optical information recording medium using two types of light sources.

[0002]

2. Description of the Related Art Conventionally, as a pasting type optical information recording medium having a recording layer made of an organic dye, FIG.
As shown in FIG. 3, the organic dye recording layer 4 containing the light absorbing agent 5 is provided on the substrate 2, and the protective substrate 10 is bonded onto the organic dye recording layer 4 with the adhesive 6. Things are known.

These organic dye recording layers 4 are irradiated with the laser beam 1 and generate thermal energy in accordance with the absorptance thereof, and the recording layers are melted or sublimated by the heat mode, as is conventionally known. , A recording pit having the shape shown in FIG. 4 is formed. Further, as shown in FIG. 4, the molten dye diffuses in the substrate to form the recording pit portion 15. Particularly, when the recording pit portion 15 as shown in FIG. 4 is formed, when the recording laser energy is relatively low as in the optical card recording medium, for example, the semiconductor laser light power is 3 to.
7 mW, light beam diameter 3-5 μm, laser irradiation time 1
It appears remarkably in the case of about 0 to 100 μsec.

When a light stabilizer or stabilizer is further added to the organic dye recording layer, the recording sensitivity of the recording layer is lowered and the formation of recording pits as shown in FIG. 4 is promoted.

[0005]

As a result of the research conducted by the present inventor, in an optical recording medium having a close contact structure using an organic dye containing a light stabilizer as a recording layer, such as an optical card, the spot diameter is about 3 μm. In addition, when recording is performed using a laser beam with a laser power of 3 to 7 mW, the heat energy generated by the laser beam causes the organic dye recording layer to be completely decomposed and decolorized at the center of the recording spot, but In the peripheral portion, as shown in FIG. 4, the organic dye is present as the organic dye 9 in the course of bleaching which has reflectivity. However, since the organic dye 8 diffused on the substrate does not have the reflectivity but functions as a so-called optical filter having the light absorption capability, the reflectance b of the recording bit portion 15 becomes low and the reflectance a of the non-recording portion becomes a. The recording contrast of the following formula obtained from the difference of 0.4 becomes 0.4 or more, and a sufficient information recording signal can be obtained.

[0006]

[Equation 1]

However, in the recording pit portion 15 as shown in FIG. 4, the organic dye 8 diffused on the substrate is photodegraded by sunlight or information reproducing laser light faster than the organic dye 9 in the process of decolorization. ..

Therefore, when the recording pit portion is continuously or intermittently irradiated with sunlight or reproducing laser light for information, the organic dye 8 relatively diffused to the substrate is more deteriorated than the organic dye 9 in the process of being decolorized. Since it is fast, the color is rapidly decolorized, and the filter effect of the organic dye 8 diffused on the substrate becomes small. As a result, the reflectance b of the recording pit portion becomes large, and the value of the recording contrast in the following equation becomes small. Therefore, there is a problem that the reliability of the recording / reproducing signal is lowered.

[0009]

[Equation 1]

In order to improve the light resistance of the recording pit as described above, it is sufficient to sufficiently decompose the dye in the recording pit portion during optical recording, but if the power of the recording laser light is simply increased, Along with that, the reproduction laser power also increases, causing a problem that photodegradation due to reproduction is accelerated.

The present invention has been made to solve the above-mentioned drawbacks of the prior art, and provides a recording method for an optical information recording medium capable of obtaining recording pits having good light stability. The purpose is.

[0012]

That is, the present invention provides a recording method of an optical information recording medium having an organic dye recording layer containing a light stabilizer, and a light source having a wavelength near the maximum absorption wavelength of the organic dye. A recording method for an optical information recording medium, characterized in that the organic dye recording layer is recorded by irradiating the organic dye recording layer with two lights generated from a light source having a wavelength near the maximum absorption wavelength of the light stabilizer.

The present invention will be described in detail below. The present invention provides an optical information recording medium having an organic dye recording layer containing a light stabilizer, a light source having a wavelength in the vicinity of the maximum absorption wavelength of the organic dye of the organic dye recording layer, and a maximum absorption wavelength of the light stabilizer. This is a dual light source recording method in which two lights emitted from light sources having wavelengths in the vicinity are simultaneously irradiated to the recording layer to perform optical recording.

By using the recording method of the present invention as described above, the photo-thermal decomposition of the organic dye and the light stabilizer in the optical recording portion of the organic dye recording layer is sufficiently promoted, and a recording pit excellent in light stability is formed. It is possible to obtain it efficiently.

The organic dye used in the organic dye recording layer in the present invention is not particularly limited, and a wide range of dyes used in optical recording media can be used. For example, those shown in the following structural formula and Table 1 Is mentioned.

[0016]

[Chemical 1]

[0017]

[Chemical 2]

[0018]

[Chemical 3]

[0019]

[Chemical 4]

[0020]

[Chemical 5]

[0021]

[Chemical 6]

[0022]

[Table 1]

(Note) (1) ε represents a molar absorption coefficient. (2) The thickness of the coating film is 500 to 1000Å.

The light stabilizer contained in the organic dye recording layer is not particularly limited and a wide range of light stabilizers used in organic recording media can be used. For example, the following structural formulas and Table 2 are shown. There are things.

[0025]

[Chemical 7]

[0026]

[Chemical 8]

[0027]

[Table 2]

That is, as shown in Table 1, λmax of the organic dye conventionally used as an optical recording medium is 7
20 to 870 nm. Also, as shown in Table 2,
The light stabilizer has a λmax of 870 to 1200 nm. Therefore, when optical recording is performed with only a light source near the λmax of the organic dye, the light / thermal decomposition rate of the light stabilizer in the optical recording portion becomes relatively slow. Therefore, due to the light stabilizer existing in the recording laser light irradiation portion, the light stability of the organic dye in the recording pit portion is high, and the recording pit in which the organic dye is sufficiently photo-thermally decomposed cannot be obtained.

In the recording method using the two light sources of the present invention, the light stabilizer is photoexcited by light having a wavelength of λmax of the light stabilizer to promote photo-thermal decomposition. as a result,
The amount of the effective component of the light stabilizer in the recording pit portion is reduced, and the photo-thermal decomposition of the dye recording layer by the light having the wavelength of λmax of the organic dye simultaneously irradiated is accelerated. As a result,
Recording pits as shown in are formed.

In FIG. 2, in the center of the recording pit,
Decolorization part 1 where the organic dye is fully photo and thermal decomposed
3 is formed. The light resistance / durability of the reproduction signal of the recording pit as shown in FIG. 2 was about 2 to 5 times better than that of the conventional recording pit shown in FIG.

In the recording pit portion formed by the recording method of the present invention shown in FIG. 2, the amount of the dye completely decomposed and decolorized portion 13 is large, and the organic dye 9a and the interface in the middle of decolorization of the undecomposed portion of the organic dye. The amount of the organic dye 8a diffused in the substrate of the light absorption filter portion is sufficiently smaller than that of the conventional recording pit shown in FIG. Further, the portion 8b in which the completely decomposed dye is diffused on the substrate hardly functions as a light absorption filter.

FIG. 1 is a schematic view showing an example of a recording method of the optical information recording medium of the present invention. In FIG. 1, 2
A light source is used, a light source 11 is an organic dye absorption laser light source having a wavelength near λmax of an organic dye, and a light source 12 is a light stabilizer absorption laser light source having a wavelength near λmax of a light stabilizer. Reference numeral 3 denotes a card-shaped optical information recording medium. Reference numeral 14 represents a pickup lens. The laser beam lights 11a and 12a are made by using an optical system that is off-axis to
The organic dye recording layer 4 containing the is simultaneously irradiated. However, if the pulse width of the laser beam light 12 a is within several μsec, the laser beam light 12 a is changed to the laser beam light 11 a.
The surface of the organic dye recording layer 4 may be irradiated with time faster than a.

Tables 1 and 2 above show λmax of typical organic dyes and λmax of light stabilizers used in the present invention. The recording light source 1 near the λmax of these organic dyes is shown.
As 1, laser diodes having wavelengths of 780 nm and 830 nm can be used, for example.

As the recording light source 12 in the vicinity of λmax of the light stabilizer, for example, a semiconductor laser having a wavelength of 1170 nm and an Nd; YLF laser having a wavelength of 1053 nm can be used. Alternatively, semiconductor lasers with wavelengths of 1200 nm and 1300 nm can be used.

As these semiconductor lasers, commercially available ones can be sufficiently used.

[0036]

EXAMPLES The present invention will be described more concretely with reference to the following examples.

Example 1 No. 1 in Table 1 was formed on a preformat-formed surface of a 0.4 mm-thick polymethylmethacrylate (PMMA) substrate preformed by the casting method. A polymethine dye having a structure of 4 and a light stabilizer IRG of Table 2
An optical recording layer containing 027 in a ratio of 3: 1 was formed by a solvent coating method. Diacetone alcohol was used as the solvent for the dye and the light stabilizer. Solvent coating solid content 3.0 wt%
Gravure coater was used to obtain a thickness of 0.
An optical recording layer of 09 μm was formed.

Next, an ethylene-vinyl acetate copolymer (EVA) adhesive (Hirodyne 7580 or Nippon Materfan OH506) was used to form 0.3 on the optical recording layer.
A protective substrate made of PMMA having a thickness of mm was laminated to obtain an optical recording medium as shown in FIG.

According to the method shown in FIG. 1, an optical recording medium obtained by the method shown in FIG. 1 has a spot of 3 μm, a pulse width of 25 μsec, and a card moving speed of 120 mm / sec. When two light source recordings were performed using a power of 3.5 mW, a Nd: YLF laser having a wavelength of 1053 nm as the light stabilizer absorbing laser light source 12, and a laser power of 2.0 mW, stable recording pits with a reproduction signal contrast of 0.65 were obtained. was gotten. The reproduction laser power is 0.2 mW. (The reproducing speed is all 400 mm / sec.) The deterioration of the reproducing light, that is, the change of the recording contrast was within 10% by the fade meter test.

The conditions of the fade meter test are: light source; xenon arc lamp 25 kW, lamp power 47 mW / cm ² temperature 40 to 45 ° C., time 250 hr.

Comparative Example 1 As a comparative example, the optical recording medium obtained in Example 1 was used with one light source of only semiconductor laser 830 nm, laser power 3.5 mW, spot diameter 3 μm, pulse width 25 μse.
When recorded under the conditions of c and card moving speed of 120 mm / sec, the contrast of the reproduced signal was 0.45. The reproduction laser power is 0.2 mW.

The change in recording contrast by the fade meter test was 25 to 30% of the initial value.

Comparative Example 2 A semiconductor laser 830 was used as the optical recording medium obtained in Example 1.
Spot diameter of 3 μm, pulse width of 25 μsec, card medium moving speed of 120 mm / s using one light source of only nm
When recorded with ec and a laser power of 5.5 mW, the recording contrast was 0.57.

However, since the reproducing laser power became 0.3 mW, the deterioration of the reproducing light was due to the reproducing laser power of 0.2 mW.
It's about twice the time.

Example 2 The light stabilizer of Example 1 was added to the light stabilizer of Table 2 IRG-012.
An optical card-shaped recording medium was prepared in the same manner as in Example 1 except that the above was changed to.

The obtained optical recording medium was used as an organic dye absorption laser light source 11, a semiconductor laser of 830 nm, laser power 3.5 mW, pulse width 50 μsec, spot diameter 3
μm, the card recording medium moving speed is 120 mm / sec, and the light stabilizer absorbing laser light source 12 has a wavelength of 1200 n.
When two-source recording with a semiconductor laser of m, a laser power of 2.0 mW, a pulse width of 50 μsec and a spot diameter of 3 μm was performed, stable recording pits with a recording contrast of 0.68 were obtained.

The change in recording contrast by the fade meter test was within 10%.

Comparative Example 3 The semiconductor laser 830n was used as the optical recording medium obtained in Example 2.
When the recording was performed using a light source of only m, a laser power of 3.5 mW, a spot diameter of 3.0 μm, a pulse width of 25 μsec, and a card recording medium moving speed of 120 mm / sec, the reproduction signal contrast was 0.45.

The change in recording contrast by the fade meter test was 20 to 25% of the initial value.

Comparative Example 4 The semiconductor laser 830n was used as the optical recording medium obtained in Example 2.
When recording was performed using a light source of m only with a laser power of 5.5 mW, a spot diameter of 3.0 μm, a pulse width of 25 μsec, and a card recording medium moving speed of 120 mm / sec, the reproduction signal contrast was 0.58.

However, since the reproduction laser power became 0.3 mW, the reproduction light deterioration rate was about 2 as compared with the reproduction laser power of 0.2 mW in Example 2 and Comparative Example 4.
The doubled defect occurred.

[0052]

As described above, recording using two lights generated from a light source having a wavelength near the maximum absorption wavelength of the organic dye of the present invention and a light source having a wavelength near the maximum absorption wavelength of the light stabilizer. By using the method, the recording contrast of the reproduction signal in the recording pit portion becomes larger and stable than when the laser power of one light source is simply increased. The light stability of the recording pit portion is about 1.5 to 3 times better than the case where one light source is used. Excellent effects such as

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a recording method of an optical information recording medium of the present invention.

FIG. 2 is a schematic diagram showing a cross section of a recording pit recorded by a two-light source recording method of the present invention.

FIG. 3 is a schematic sectional view of a conventional optical card recording medium.

FIG. 4 is a partially enlarged schematic sectional view of a recording pit of a conventional optical card recording medium.

[Explanation of symbols]

 1 Laser Beam 2 Substrate 3 Optical Information Recording Medium 4 Organic Dye Recording Layer 5 Light Stabilizer 6 Adhesive 7 Concave Pregroove 8, 8a Organic Dye 8b Diffused on Substrate 8b Part where Completely Degraded Dye Diffuses on Substrate 9, 9a Organic dye in the middle of decolorization 10 Protective substrate 11 Organic dye absorption laser light source 12 Light stabilizer absorption laser light source 11a 11 laser beam light 12a 12 laser beam light 13 Dye complete decomposition decolorization part 14 Pickup lens

Claims (1)

[Claims] 1. A method for recording an optical information recording medium having an organic dye recording layer containing a light stabilizer, comprising: a light source having a wavelength near the maximum absorption wavelength of the organic dye and a wavelength near the maximum absorption wavelength of the light stabilizer. Generated from a light source having
A recording method for an optical information recording medium, characterized in that the organic dye recording layer is irradiated with two lights for recording.