JPH02204087A - Optical recording method and optical recorder - Google Patents

Abstract

PURPOSE:To record an image which can be directly identified with the naked eye by recording an optical recording medium on which a light absorption layer and a heat sensitive coloring layer are laminated on a hydrophilic base material by using a laser light condensed via a specific condensing lens. CONSTITUTION:An optical recording medium on which a heat sensitive coloring layer containing basic dye and organic developer and a light absorption layer containing near infrared absorber are laminated on a hydrophilic base material is irradiated on its optical recording surface with a laser output from a laser light emitting element with a low output laser device by converting the laser into parallel beam via a lens system and then converging it via a condensing lens having 0.1 - 0.5 of number of apertures (N.A) and 0.5mm or more of focal length. When thus recorded, even if the recording surface has an uneven part or waviness which cannot be avoided when a hydrophilic base material is employed, the deviation of the focusing position of an irradiated light from the recording surface is not so increased. Accordingly, a recording density of a readable range and a contrast can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an optical recording medium in which recording is performed by laser beam irradiation.

(Prior art) The thermal recording method is a direct recording method that does not require development or fixing.
It is widely used in facsimiles and printers due to its excellent operability and maintainability.

However, this method cannot be used with thermal heads or heat-generating ICs.
Because the pen is brought into direct contact with heat-sensitive recording paper for heating recording, colored melt adheres to the thermal head and heat-generating IC pen, causing problems such as adhesion of scum and sticking, resulting in problems with recording failure and deteriorating recording quality. There was a dot.

Particularly in the case of continuous line drawing in the recording flow direction, such as in block printers, it has been impossible to perform continuous printing without causing problems such as adhesion of residue.

Furthermore, the image resolution of the thermal head is generally 8 lines/square, and it is said to be difficult to increase the resolution beyond this.

Therefore, a non-contact recording method using light has been proposed as a method to eliminate problems such as adhesion of residue and sticking and to further improve resolution.

JP-A No. 54-4142 discloses a heat-sensitive recording material in which a support is coated with a heat-sensitive recording layer mainly containing leuco dye, in which a metal compound having lattice defects is used to create lattice defects. It is disclosed that thermal recording is possible by absorbing light in the visible and infrared regions of a metal compound and converting it into heat.

JP-A No. 58-209594 discloses that 0. 8-2 l
JP-A-58-94494 discloses an optical recording medium in which at least one set of a near-infrared absorber having an absorption wavelength in the near-infrared region of t m and a thermosensitive coloring material are laminated on a substrate. It consists of two or more types of heat-sensitive coloring materials and a compound that has a maximum absorption wavelength of near-infrared light of 0.7 to 3 μm! A recording medium is disclosed in which a base material is coated with a fiber or two or more types of near-infrared absorbers, and recording on these recording media is performed using a hot plate and a laser beam with a wavelength near the near-infrared. It discloses what can be done by

(Problem to be solved by the invention) The above publication describes an optical recording medium whose base material is a non-hydrophilic material such as glass or film, and an optical recording medium whose base material is paper, which is a hydrophilic material. However, the relationship between the properties of the substrate and the conditions of the recording system in order to make a practical optical recording medium has not been clarified.

Recording on an optical recording medium using a base material made of a hydrophilic material is a macroscopic printing system compared to an optical disk used as an optical memory. In other words, since optical discs are read using laser light, extremely microscopic precision is required, with a spot diameter on the order of 1 micron.In contrast, with optical recording media, recorded information can be read directly by humans with the naked eye. A spot diameter of lO to xoo microns is required for reading.

Also, compared to optical discs that are based on non-hydrophilic materials such as glass or plastic plates, when the support of the optical recording medium is a hydrophilic support such as paper, there are much more unevenness and valleys. The depth of the recording paper is generally 5 to 6 microns even for recording paper, and even more than that, irregularities in the height of the sheet surface due to the waviness of the paper can be seen. Therefore, a certain degree of tolerance regarding focus crowding is absolutely necessary.

Furthermore, since optical discs are mechanically readable, it is sufficient to obtain optical contrast at the reading wavelength, whereas in order for humans to directly read the recorded information, contrast that can be read by the naked eye is required. .

Descriptions regarding recording using conventional laser beams, including the above-mentioned publications, are based on the laser irradiation conditions required to record on an optical recording medium using a hydrophilic substrate as a support so as to satisfy the above conditions. It is vague or unclear, and the knowledge necessary for practical use is not available.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical recording method and a recording apparatus that satisfy the above-mentioned conditions and are capable of recording images that can be directly read with the naked eye using laser light.

(Means for solving the problem) The above problem is achieved by laminating a heat-sensitive coloring layer containing a basic dye and an organic color developer and a light absorption layer containing a near-infrared absorber on a hydrophilic base material. An optical recording medium with a focal length of 0.5 m
By using a laser beam condensed by a condensing lens with a numerical aperture (N, A) of 0, 1 to 065 and a numerical aperture (N, A) of
They discovered that clear images can be obtained and completed the present invention.

The optical recording medium of the present invention is characterized in that a hydrophilic base material is used as the base material. The hydrophilic base material is mainly paper, but it is mainly made of plant fibers such as bulbs and cotton, and if necessary, animal or mineral fibers or synthetic fibers can be used as long as they do not impair the hydrophilic properties of the fabric. They may be used in combination.

A heat-sensitive coloring layer and a light-absorbing layer are laminated on this hydrophilic base material, but the order is not particularly limited. - The order of the heat-sensitive coloring layer may be used. Further, a protective layer may be provided on the top layer to reduce external influences, and particularly when the heat-sensitive coloring layer is the top layer, favorable results are brought about. A preferred method is to incorporate a near-infrared absorber into the protective layer so that the protective layer simultaneously functions as a light absorbing layer. Furthermore, another layer such as a pigment layer that does not significantly impede heat transfer may be provided between the light absorption layer and the thermosensitive coloring layer.

Light sources necessary for optical recording on optical recording media include semiconductor lasers, diode bombing YAG lasers, He-N
E-gas laser is a dye laser, etc., and in order to be used as an office recording device, a laser with a low output of about 1,100 mW is preferable from the viewpoint of device miniaturization, safety, cost, etc.

The laser output from such a laser emitting element is parallelized by a lens system]7, and then the numerical aperture (N, A
) is 0.1 to 0.5, and the light is focused by a condensing lens with a focal length of 0.5 mm or more and irradiated onto the optical recording surface. The upper limit of the focal length is determined by the output of the laser light-emitting element used and the structure of the recording device, and can be determined by the distance between the laser light emitting surface and the light receiving surface of the optical recording medium. According to experiments, it was found that if the focal length becomes too long, the recording density will not increase even if the laser output is increased, and that it is preferable to set the focal length to 50 mrn or less as an upper limit.

Focal length is 0.5 mrn or less or N, A, [ is 0.
If it is 5 or more, the distance from the lens to the recording medium is short, and the lens may be contaminated with substances that volatilize from the surface of the recording medium due to laser beam irradiation, or slight unevenness on the recording surface that is inevitable when using a hydrophilic base material. Due to the undulation of the recording medium,
Since the imaging position of the irradiation light and the recording surface are largely shifted, the recording density becomes non-uniform, which is inconvenient.

Furthermore, if the N and A values are less than O and i, sufficient print density cannot be obtained.

Focal length M0.5mrrx or more, open aperture 0.1-0,
The condensing lens No. 5 can be made by combining one lens or several lenses. As the number of lenses combined increases, the reduction in output between lenses increases, so
It is preferable to set the number to about 5 sheets.

The light-absorbing layer is generally obtained by applying a paint consisting of a near-infrared absorber, a binder, and, if necessary, a white pigment, onto a hydrophilic substrate.

The near-infrared absorber may be one that has absorption in the near-infrared region of 0.7 to 3 mμ, and is described in Japanese Patent Application Laid-Open No. 52-68852.
No., JP-A-58-209594, JP-A-58-944
In addition to cyanine dyes, one thiol nickel substance, and squarylium dyes disclosed in Publication No. 94, nitrone compounds and their metal complexes, and polymethine compounds in ``Near Infrared Absorbing Dye J (Kagaku Kogyo 43゜ May 1986 issue). A pigment based on cyanine, a combination of thiol and cobalt or palladium.

Phthalocyanine dyes, triallylmethane dyes.

Immonium or diimmonium dyes, naphthoquinone dyes, or thiourea derivatives discovered by the present inventors and atoms other than those in Groups IA and IIA of the periodic table ff
The application of the present inventors relates to an optical recording medium using a treatment product obtained by mixing and heat-treating 140 or more metal organic acid salts, alcolades, or hydroxides, or a dispersible near-infrared absorber. These are dispersible near-infrared absorbers such as sulfide shells and graphite described in Japanese Patent Application No. 63-272702. In addition, the conventionally known cyanine dyes, thiol nickel complexes, triallylmethane dyes, etc. are near-infrared absorbers that dissolve in water or solvents. , also patent application 1986-
No. 272702.

The heat-sensitive coloring layer is exactly the same as the coloring layer of heat-sensitive recording paper, which contains a known electron-donating colorless dye and an electron-accepting organic color developer as color-forming components, and is completely different from all the known coloring layers of heat-sensitive recording paper. technology can be applied. Basic colorless dyes are
Triphenylmethane type such as crystal violet lactone, fluoran type such as 3-diethylami71-6-methyl/-7-amyritsufluoran, 3-(4-diethylami7-2-ethoxyphenyl>-3-(1-ethyl) -2-methylindol-3-yl)-4-azaphthalide and other azaphthalides 8 or 3,6゜6'-tris(dimethylamino)spiro[fluorein-9,3-
Leuco dyes such as furusrein dyes such as [phthalide] etc. Organic color developers include bisphenol Am and 4-hydrotocybenzoic acid ester.

4-hydroxyphthalic acid diesters, phthalic acid monoesters, bis=(hydroxyphenyl)phenyl sulfides, 4-hydroxyphenylaryl sulfones, 4-hydroxyphenylaryl sulfonates, 1
．． 3-di[2-(hydroxyphenyl)-2-propyl]-benzenes.

There are 4-hydroxybenzoyloxybenzoic acid ester and bisphenol sulfone av.

Examples of the binder include fully saponified polyvinyl alcohol having a degree of polymerization of 200 to 1900, modified polyvinyl alcohol such as amide-modified polyvinyl alcohol, hydroxydiethylcellulose, styrene-butadiene copolymer, and the like.

In addition, fatty acid amide, montan wax, etc. are used as sensitizers or quality control agents, and clay calcium carbonate,
Alternatively, fillers commonly used in the paper processing field, such as plastic pigments, can be added. In particular, hollow plastic pigments are preferable because they have good near-infrared light reflection (and good heat retention properties). The basic colorless dyes, organic color developers, binder sensitizers, fillers and quality control agents described in Japanese Patent No. 63-272702 can be used in the same manner in the present invention.

The types and amounts of the organic color developer, basic colorless dye, binder, sensitizer, filler, and other various components in the color forming layer used in the present invention are determined according to the required performance and recording suitability, and in particular, Typically, but not limited to, 1 part basic dye.

Organic color developer 3-12 parts, sensitizer 3-12 parts, filler 1-1
20 parts of the binder is used, and the binder accounts for 10 parts of the total solid content of the coloring layer.
~25 parts is appropriate.

The organic color developer, basic colorless dye, and sensitizer are each individually or together with other materials added as necessary, and are reduced to a particle size of several microns or less using a grinding machine such as a ball mill, attritor sand grinder, or an appropriate emulsifying device. The mixture is atomized until it becomes granulated, and the various quality control agents described above are further added thereto depending on the binder and the purpose to prepare a coating liquid.

The coating liquid obtained in step 5 is applied onto a substrate or a light absorbing layer to form a heat-sensitive coloring layer. By laminating the thermosensitive coloring layer on the light absorption layer, the coloring of the optical recording layer is further hidden, resulting in an optical recording medium with a desirable appearance.

The surface of the heat-sensitive coloring layer is exposed to moisture, gas, water, and solvents.

It is a preferred method to provide a protective layer that reduces or prevents contamination from the external environment, such as oil.

The protective layer must be transparent to visible light and have no adverse effect on the thermosensitive coloring layer, and one or more types of binders usually used in the thermosensitive coloring layer are selected as the protective layer.

When a soluble near-infrared absorber is contained in the protective layer or between the protective layer and the thermosensitive coloring layer, the sensitivity of the -layer optical recording medium is increased.

(Function) As described above, an optical recording medium in which a light absorption layer containing a near-infrared absorber and a heat-sensitive coloring layer containing a basic dye and an organic color developer are laminated on a hydrophilic base material, Focal length 0.5rnrn
Above, numerical aperture (N, A) O,i~0. When recording using laser light focused by the condensing lens in step 5, even if a hydrophilic base material is used and there are unavoidable unevenness or waviness on the recording surface, the imaging position of the irradiated light and the recording can be maintained. Since the surface deviation is not too large, it is thought that recording density and contrast within the readable range can be obtained.

(Examples) In the following examples, parts and percentages are by weight.

Point 1''■2 The dye dispersion (liquid A) and the color developer dispersion (liquid B) having the following formulations were wet ground separately in a sand grinder for 1 hour, and then 6.3 parts of liquid A was added. , 25 parts of liquid B and 2 parts of silica
25 parts of a 5% dispersion was mixed to make a heat-sensitive coloring coating liquid, and this coating liquid was mixed with 25 parts of a 5% dispersion. A heat-sensitive coloring layer was obtained by applying 5 g/d on a 60 g/rrt high-quality paper using a Mayer bar and drying.

(A) Liquid: Dye dispersion Black coloring dye: OD8 2.0 parts 10% PVA
Aqueous solution 3.4 parts water
1.9 parts ODB: 3-diethylamino-6-methyl-7-anilinofluorane (B) Solution: Color developer dispersion Color developer: BPA 6.0 parts P-benzylbiphenyl 4.0 parts 10% PVA aqueous solution
12.5 parts water
2.5 parts BPA: Bisphenol A Next, 6 parts of the near-infrared absorber dispersion liquid C of the following formulation and 105 parts of the protective layer solution were mixed, and using a Mayer bar, the mixture containing the near-infrared absorber An optical recording sheet was obtained by coating the protective layer coating liquid on the heat-sensitive coloring layer.

(C) Liquid: Near-infrared absorber dispersion Near-infrared absorber (ICIS116510) 10 parts lO% PVA aqueous solution 50 parts water
40 parts average particle size is 0
．． Wet dispersion was performed using a sand grinder until the particle size was 8μ.

(D) Solution: Protective layer 10% PVA aqueous solution 100 parts Glyoxal (40%) 5 parts The optical recording paper thus prepared was coated with a semiconductor laser head (laser diode collimator head LDC-8330-CINC: Applied Oftech). The optical recording paper was irradiated with a laser beam and optically printed using the apparatus shown in FIG. 1, which was a combination of a condenser lens and a condensing lens.

The condenser lens has a numerical aperture (N, A value) of 064°O,5,
0, 28, 0, and 16 lenses were used, and the irradiation time was 1.
The test was carried out for 1500 seconds.

The recorded image and ground color were measured as follows, and the results are shown in Table 1.
It was shown to.

Density of recorded image (colored spot): Measured using a densitometer (PDM-5 manufactured by Konishiroku Photo Industry Co., Ltd.), and the measured value was converted to Macbeth density.

Background color of optical recording paper: Measured with a Macbeth densitometer.

Inugami: The same method as in Example 1 was used except that the combinations of black dye and developer used in the heat-sensitive coloring layer of Example 1 were ODB/POB, 0DB-2/BPA1 and S-205/BPA. A recording paper was created. Using a condensing lens with a numerical aperture of 0°28,
Recording was made in the same manner as in Example 1. The measured values of image density and ground color are shown in Table 1.

The structures of the black dye and developer are shown below.

Dye: 0DB-2: dibutylamino-6-methyl-
7-anilinofluorane S-205: a-(N-ethyl-N~isoamyl)-
6-Methyl-7-anilinofluorane color developer: POB: p-Hydroxybenzoic acid benzyl ester ratio" Example - Condensing light with a numerical aperture of 0.62.0°08 onto the optical recording paper of Example 1. Laser light was irradiated in the same manner as in Example 1 except that a lens was used and a condensing lens was not used. The measured values of image density and ground color are shown in Table 1.

As is clear from Table 1, when the condensing lenses of Examples 1 and 2 whose N and A values are within the range of the present invention are used, the dye and developer of the thermosensitive coloring layer are A clear black image was obtained regardless of the combination, whereas Comparative Example 1 with N and A values of 0.62, which is outside the invention, had a working distance of 0.8 mm or less and did not touch the recording paper. A problem occurred and a recorded image could not be obtained, and the N and A values were 0.0.
In No. 8, the printing energy was insufficient, resulting in a faint image, and the contrast with the background color was so small that it was difficult to distinguish it with the naked eye. Moreover, when no condensing lens was used, no image was obtained at all.

(Effects of the Invention) As explained above, a light absorption layer containing a near-infrared absorber and a heat-sensitive coloring layer containing a basic dye and an organic color developer are laminated on the hydrophilic base material 5. When recording on an optical recording medium with a laser beam, the laser beam is focused at a focal length of 0.5 mm or more,
When condensing and recording with a condensing lens with a numerical aperture (N, A) of 0°1 to 0.5, a record that can be read with the naked eye can be obtained even if there are surface irregularities and undulations characteristic of hydrophilic substrates. This made it possible to use low-power lasers, and brought good results in promoting the practical application of heat mode optical recording media.

[Brief explanation of the drawing]

Claims (2)

[Claims] (1) An optical recording medium in which a light absorption layer containing a near-infrared absorber and a heat-sensitive coloring layer containing a basic dye and an organic color developer are laminated on a hydrophilic base material at a focal length of 0. An optical recording method characterized by recording using a laser beam focused by a condenser lens having a diameter of 5 mm or more and a numerical aperture (NA) of 0.1 to 0.5. (2) Laser light recording performed on an optical recording medium in which a light absorption layer containing a near-infrared absorber and a heat-sensitive coloring layer containing a basic dye and an organic color developer are laminated on a hydrophilic base material. In the apparatus, the recording device includes a laser emitting element and a focal length of 0.
．． A laser beam recording device characterized by having a laser beam condensing lens having a diameter of 5 mm or more and a numerical aperture (NA) of 0.1 to 0.5.