JPH1152264A - Image recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an image recorder capable of eliminating interference fringe caused by the interference of a laser beam reflecting component at the time of exposure, and to improve image quality. SOLUTION: This image recorder 30 forming a latent image on recording material A by scanning-exposure with a laser beam L is provided with a phase varying means 33 changing the laser beam L into luminous flux having a random phase difference. Then, it is desirable to provide the means 33 so as to freely move in the optical axis direction of the laser beam L in the vicinity of the focusing point of the laser beam L. It is desirable to provide the means 33 so as to freely move in the direction nearly orthogonal to the optical axis direction of the laser beam L near the focusing point of the laser beam L. Furthermore, it is desirable that the movement thereof in the direction nearly orthogonal to the optical axis direction of the laser beam L is performed in synchronization with the main scanning of the laser beam L.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image recording apparatus for performing dry recording using a photothermographic material, and more particularly, to an improvement in an image exposure section for forming a latent image on a recording material by scanning exposure with a laser beam. It is about.

[0002]

2. Description of the Related Art As an image recording apparatus for recording medical images such as CT and MR, a dry system for obtaining a developed image by performing thermal development using a photothermographic material without performing a wet development process is known. I have. In this type of image recording apparatus, a latent image is formed by exposing a photothermographic material by scanning exposure with a laser beam in an image exposure section. FIG. 5 is a conceptual diagram of an image exposure section of a conventional image recording apparatus. The image exposure unit 1 includes a light source 3 that emits laser light L, a recording control device 5 that drives the light source 3, a polygon mirror 7 that is an optical deflector, fθ
A laser beam L having a lens 9 and a falling mirror 11 and modulated in accordance with a recorded image is deflected in the main scanning direction (perpendicular to the plane of FIG. 5) and is incident on a predetermined recording position X. The sub-scanning conveyance means 13 has a pair of conveyance rollers 15 and 17 arranged so as to sandwich the recording position X, and the heat development photosensitive material (hereinafter, “recording material A”) is moved by the conveyance roller pairs 15 and 17. ) Is conveyed in the sub-scanning direction (the direction of the arrow a in FIG. 5) orthogonal to the main scanning direction while maintaining the recording position X. Here, since the laser light L pulse-width modulated according to the recorded image is deflected in the main scanning direction, the recording material A is two-dimensionally scanned and exposed by the laser light to record a latent image. The recording material A on which the latent image has been recorded in the image exposure section 1 is then conveyed to a heat developing device (not shown), and is thermally developed by heating to obtain a latent image as a visible image.

[0003]

The recording material A used in the above-mentioned conventional image recording apparatus has an emulsion layer 23 on a support 21 as shown in FIG.
Are stacked. In such a recording material A,
At the time of scanning exposure with laser light, reflection occurs due to a difference in refractive index at the boundary surface between the layers. For this reason, the incident light L is divided into a component L1 transmitted as it is, a component L2 reflected by A and B, and a component L3 reflected by C and D. An optical path difference occurs between these components L1, L2, and L3. The components L1, L2, and L3 are strongest when the exposure difference is an integral multiple of the wavelength of the laser light, and weakest when the exposure difference is half a wavelength. The exposure difference also varies depending on the scanning angle of the laser beam and the thickness of each layer, and varies in various ways depending on the combination of these, resulting in a problem that interference fringes are generated in the recorded image.

[0004] Further, with respect to a change in the thickness of the recording material A,
Interference fringes occur as contour lines for each wavelength. On the other hand, if the change in the thickness of the recording material A is eliminated, the occurrence of interference fringes due to this factor is eliminated. However, it is difficult to suppress the change in the thickness of the recording material A to a wavelength unit or less. Also led to a significant increase in costs.

The present invention has been made in view of the above circumstances, and has as its object to provide an image recording apparatus capable of eliminating interference fringes caused by interference of a laser beam reflection component at the time of exposure and to improve image quality. I do.

[0006]

According to a first aspect of the present invention, there is provided an image recording apparatus for forming a latent image on a recording material by scanning exposure with a laser beam. It is characterized by comprising a phase varying means for making a light beam having a random phase difference.

The image recording apparatus can be characterized in that the phase varying means is provided so as to be movable in the optical axis direction of the laser light near the focal point of the laser light.
Further, the phase varying means may be provided so as to be movable in a direction substantially orthogonal to an optical axis direction of the laser light in the vicinity of a focal point of the laser light. Furthermore, the movement of the laser light in a direction substantially orthogonal to the optical axis direction may be synchronized with the main scanning of the laser light.

[0008] Preferably, the phase changing means is a ground glass. The phase changing means may include a fine dispersion contained in the light transmitting layer.

In this image recording apparatus, scanning exposure is performed by a light beam having a random phase, and a change in intensity due to a phase difference is caused in an overlap between a component directly passing through the recording material and a component reflected in the recording material. The occurrence of interference fringes is suppressed. In an image recording apparatus in which the phase varying means is provided so as to be movable in the direction of the optical axis of the laser light, the degree of coherence can be changed, and the contrast of interference fringes becomes inconspicuous.

In an image recording apparatus in which the phase varying means is provided so as to be movable in a direction substantially perpendicular to the optical axis of the laser light, the coherence is improved, and the laser light having a sufficient intensity and shape is formed on the recording material. Light can be collected. Further, in an image recording apparatus in which the movement of the laser light in the direction substantially orthogonal to the optical axis direction is synchronized with the main scanning of the laser light, an increase in cost for the synchronous movement is minimized.

[0011] In an image recording apparatus in which the phase varying means is made of ground glass, the phase varying means is inexpensive. In an image recording apparatus in which the phase variable means includes a fine dispersion in the light transmission layer, the randomness of the phase transmission characteristics can be easily set.

Recording materials applicable to the present invention include, for example,
The photothermographic material has a thickness of several hundred microns
An emulsion layer having a thickness of about several μm to several tens μm on a m base film, and a protective layer coated on the surface thereof, and a back coat layer and an antihalation layer coated on the back surface of the base film. . Then, in order to improve the sensitivity, the AgX particles of the light-sensitive material were made smaller (average of 0.2 μm or less), and the amount of coated silver was reduced (3).
g / m ² or less), and the absorbance of the emulsion layer is reduced (at a laser wavelength of 0.5 or less).

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an image recording apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is a schematic configuration diagram of an image exposure section of an image recording apparatus according to the present invention.
The same parts as those shown in FIG. 5 are denoted by the same reference numerals, and a description thereof will be omitted. The image exposure unit of the image recording device 30 includes a light source 3 that emits a laser beam L, a recording control device 5 that drives the light source 3, and an optical system (lenses 31a and 31a).
b, 31c, 31d), a polygon mirror 7 serving as an optical deflector, an fθ lens 9, a falling mirror 11, and a phase varying unit 33, and a laser beam L modulated according to a recorded image. The light is deflected in the main scanning direction (perpendicular to the plane of FIG. 1) and is incident on a predetermined recording position X. The sub-scanning conveyance means 13 has a pair of conveyance rollers 15 and 17 arranged so as to sandwich the recording position X.
7, while conveying the recording material A at the recording position X, the recording material A is transported in the sub-scanning direction (the direction of arrow a in FIG. 1) orthogonal to the main scanning direction.

Here, the laser light L pulse-modulated according to the recorded image is deflected in the main scanning direction.
The recording material A is two-dimensionally scanned and exposed by the laser beam L. The thin laser light L emitted from the light source 3 is expanded after being condensed by the lens 31a, converted into a thick parallel light by the lens 31b, and converted into a predetermined thin parallel light by the lens 31d after being collected by the lens 31c. You. The laser beam L from the lens 31 d is deflected by the polygon mirror 7 and is two-dimensionally scanned and exposed through the fθ lens 9, whereby a latent image is recorded on the recording material A.

The phase changing means 33 is provided in a light beam in which the laser light L is condensed or expanded by a lens. In this example, it is interposed between the lens 31c and the lens 31d. The phase changing means 33 has a random phase transmission characteristic with respect to the laser light L, and gives a random phase change to each portion of the light beam. As the phase changing means 33, for example, ground glass having fine irregularities on the surface can be used.

The phase change by the phase changing means 33 will be described below with reference to FIG. FIGS. 2A and 2B are explanatory diagrams showing a phase change by the phase variable means. FIG. 2A shows a state in which the phase variable means is arranged close to the light beam converging point P, and FIG. It shows the state where it is arranged. FIG.
In (B), if the light diffusion of the phase variable means 33 is small,
The phase of the light reaching the points S and T is determined by the S
Phase transmission characteristics φ at point 11 and point T11 (S11)
And φ (T11). The phase difference Δφ between point S and point T due to this phase change is Δφ = ΔφST + φ
(S11) -φ (T11). Δ
φST is a phase difference determined by the arrangement of the points ST.

The phase difference Δφ is such that the distance between the points S11 and T11 is sufficiently large compared to the randomness of the phase transmission characteristic of the phase variable means 33 (in the case of ground glass, the irregularities thereof), and the phase difference When the phase transmission characteristic causes a phase change sufficiently larger than the wavelength of the transmitted light, the probability of conversion from + π to -π in terms of phase angle becomes uniform. That is, under the above conditions, the phase relation of the light reaching between the points ST is random, and the light reaching between the two points does not seem to interfere even if they are overlapped or collected by an appropriate optical system. .

As shown in FIG. 2A, when the phase changing means 33 is disposed at a position close to the light beam converging point P, the points S, T
, The points S12 and T12 on the phase variable means 33 approach. In this case, the phase transmission characteristics of the phase varying means 33 at the points S12 and T12 have some relevance. If the distance between the points S12 and T12 becomes very small, the difference in the phase transmission characteristics of the phase varying means 33 at this point becomes a very small value. Therefore, the phase difference of each light flux between the points S and T changes randomly.

In the image recording apparatus 30, when the laser beam L is converged by the lens 31c, the phase is randomly changed by each transmitting portion when passing through the phase varying means 33, and the focusing and the lens 31d are passed through the phase varying means 33. The laser beam L, which has been converted into a parallel light beam, becomes scanning light on the recording material A as focus light having a random phase. The focal light is light in which light fluxes having random phases are gathered. The focus light with the random phase suppresses a change in intensity due to a phase difference in an overlap between a component directly passing through the recording material A and a component reflected in the recording material A, and suppresses the generation of interference fringes.

In the above example, the phase change range between the points S and T is considerably smaller than π in terms of the phase angle. Therefore, when the light reaching between points S and T is caused to interfere, interference fringes remain with a slight degree of coherence. Therefore, as shown in FIGS. 2A and 2B, if the phase variable means 33 is moved in the optical axis direction (the direction of the arrow X), the degree of coherence can be changed, and the contrast of the interference fringes is noticeable. It can be adjusted so that the laser beam L having the required intensity and shape is condensed on the recording material A while leaving the coherence of the laser beam L.

Further, it is difficult to focus the laser beam L substantially at one point at the light beam focusing point P, and the difference in phase transmission characteristics between the points S and T may not be sufficiently small. In such a case, as shown in FIG.
If 3 is moved at a certain speed in a direction substantially perpendicular to the optical axis (the direction of arrow Y), movement between points S1 and S2 and movement between points T1 and T2 on the phase changing means 33 can be caused. As a result, since the phase transmission characteristics between T1 and S2, which are common portions of the two, are equal, the laser beam L having sufficient intensity and shape is improved on the recording material A by improving the coherence. be able to.

At this time, since the intensity of the laser beam L may change depending on the position of the movement of the phase varying means 33, it is necessary to synchronize the main scanning of the laser light L with the movement of the phase varying means 33. Is preferred. For example, the phase variable means 33 reciprocates once in a direction substantially perpendicular to the optical axis in one main scan. Alternatively, the phase varying means 33 is provided rotatably about an axis substantially parallel to the optical axis, and the phase varying means 33 is provided in one main scan.
May be rotated once. As described above, if the correction is performed together with the shooting accompanying the main scanning, the increase in cost for the synchronous movement can be minimized.

When the degree of coherence is further adjusted, as shown in FIGS. 3A and 3B, adjustment is made by moving the phase varying means 33 in the optical axis direction (the direction of arrow X). Can be.

In the above embodiment, the case where the ground glass is used as the phase changing means 33 has been described as an example.
The phase changing means 33 may be formed of a layer containing a fine dispersion, for example, as shown in FIG. 4A, a binder 41 made of polycarbonate or the like containing glass beads 43, or as shown in FIG. Microcapsule 4 as shown
5 may be included. According to the configuration including such a fine dispersion, it is possible to relatively easily set the randomness of the phase transmission characteristic to a desired value.

Hereinafter, recording materials usable in the present invention will be described. This recording material is disclosed in Japanese Patent Application No. 9-185724, and is obtained by preparing an organic silver dispersion-A and then processing it into a coated sample.

(Preparation of Organic Silver Dispersion-A) Behenic acid 40
g, 7.3 g of stearic acid and 500 ml of water at a temperature of 90 ° C.
For 15 minutes, 187 ml of 1N NaOH was added over 15 minutes, 61 ml of a 1N aqueous nitric acid solution was added, and the temperature was lowered to 50 ° C. Next, 124 ml of a 1N silver nitrate aqueous solution was added over 2 minutes, and the mixture was stirred as it was for 30 minutes. Thereafter, the solid content was separated by suction filtration, and the conductivity of the filtrate was 30 μS /
The solid was washed with water until it reached cm. The solid content thus obtained is treated as a wet cake without drying,
10 g of polyvinyl alcohol (trade name: PVA-205) and water were added to a wet cake equivalent to 100 g of dry solids to make the total amount 500 g, and then predispersed with a homomixer.

Next, the pressure of the pre-dispersed stock solution was adjusted to 1750 kg / cm ² with a dispersing machine (trade name: Microfluidizer M-110S-EH, manufactured by Microfluidics International Corporation, using G10Z interaction chamber). Then, the mixture was treated three times to complete the preparation of a silver salt of an organic acid microcrystal dispersion having a volume-weighted average diameter of 0.93 μm. Particle size measurements are available from alvern Instruments L
Performed with MasterSizerX manufactured by td.

(Preparation of Silver Halide Grain-A) Water 700
22 g of phthalated gelatin and 30 ml of potassium bromide per ml
After dissolving mg and adjusting the pH to 5.0 at a temperature of 40 ° C.,
159 ml of an aqueous solution containing 18.6 g of silver nitrate and an aqueous solution of potassium bromide were added over 10 minutes by a controlled double jet method while keeping pAg at 7.7. Then, 476 ml of an aqueous solution containing 55.4 g of silver nitrate and an aqueous solution containing 8 μmol / l of dipotassium hexachloridate and 1 mol / l of potassium bromide were maintained for 30 minutes by a controlled double jet method while maintaining the pAg at 7.7. Was added. Thereafter, the pH was lowered to cause coagulation sedimentation, desalting treatment was performed, and 0.1 g of phenoxyethanol was added, pH 5.9 and pAg 8.
Adjusted to zero. The resulting particles have an average particle size of 0.07
Cubic particles having a μm, a variation coefficient of the projected area diameter of 8%, and a (100) plane ratio of 86%.

The temperature was adjusted for the adjusted silver halide grains A.
The temperature was raised to 60 ° C. and 8 moles of sodium thiosulfate per mole of silver.
5 μmol and 11 μmol of 2,3,4,5,6-pentafluorophenyldiphenylphosphine selenide
Mole of the following Derul compound 1, 3.3 μmol of chloroauric acid and 230 μmol of thiocyanic acid were added, and the mixture was aged for 120 minutes.

Thereafter, the temperature was changed to 40 ° C., and the following sensitizing dye-A was added with stirring at 3.5 × 10 ⁻⁴ mol with respect to the silver halide, and after 5 minutes, the following compound-A was halogenated. 4.6 × 10 ⁻³ mol was added to silver, and the mixture was stirred for 5 minutes and then rapidly cooled to 25 ° C. to complete the preparation of silver halide grains-A.

[0031]

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[0032]

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[0033]

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(Preparation of Material Solid Fine Particle Dispersion) Tetrachlorophthalic acid, 1,1-bis (2-hydroxy-3,5
-Dimethylphenyl) -3,5,5-trimethylhexane and tribromomethylphenylsulfone to prepare solid fine particle dispersions. For tetrachlorophthalic acid,
0.81 g of hydroxypropyl methylcellulose and water 9
4.2 ml was added, stirred well, and left as a slurry for 10 hours. Thereafter, 100 ml of zirconia beads having an average diameter of 0.5 mm was prepared, placed in a vessel together with the slurry, and dispersed (（G sand grinder mill:
The mixture was dispersed for 5 minutes with IMEX Co., Ltd. to obtain a dispersion of solid fine particles of tetrachlorophthalic acid. Particle size is 70wt%
Was 1.0 μm or less. For other materials, the amount of the dispersant used and the dispersion time were changed to obtain the desired average particle size, and solid fine particle dispersions were obtained for each material.

<Preparation of Dispersion of Polymer Fine Particles Containing Dye> A solution comprising the following dye A (2 g), methyl methacrylate-methacrylic acid copolymer (85:15) (6 g), and 40 ml of ethyl acetate was heated to 60 ° C. After heating and dissolving, 100 ml of an aqueous solution containing 5 g of polyvinyl alcohol
In addition, the mixture was finely dispersed with a high-speed stirrer (homogenizer, manufactured by Nippon Seiki Seisakusho) at 12,000 rpm for 5 minutes to obtain emulsified dispersion P of polymer fine particles having an average particle diameter of 0.3 μm.

[0036]

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(Preparation of Emulsion Layer Coating Solution-1) The silver halide grains-A were added to the previously prepared organic silver microcrystal dispersion-A (equivalent to 1 mol of silver) at 10 mol% of silver halide / organic acid. Emulsion coating liquid-1 was prepared by adding silver equivalents and the following binder and developing materials. Binder: Luckstar 3307B (manufactured by Dainippon Ink and Chemicals, Inc .; SBR latex) 430 g Material for development: Tetrachlorophthalic acid, 5 g of the above dispersion 1,1-bis (2-hydroxy-3,5-dimethyl) Phenyl) -3,5,5-trimethylhexane, 98 g of the above-mentioned dispersion phthalazine, 9.2 g tribromomethylphenylsulfone, 12 g of the above-mentioned dispersion 4-methylphthalic acid, 7 g Dye: the above dye A, 4 g of the same The dye-containing polymer fine particle dispersion

The rack star 3307 used above
B is a polymer latex of a styrene-butadiene copolymer, and the average particle size of the dispersed particles is 0.1 to 0.15.
It is about μm.

(Preparation of Coating Solution for Emulsion Surface Protective Layer) For 10 g of inert gelatin, 0.26 g of surfactant A, 0.09 g of surfactant B, and silica fine particles (average particle size of 2.5
μm), 0.9 g, 1,2- (bisvinylsulfonylacetamido) ethane, 0.3 g, and water, 64 g, were added to form a surface protective layer.

[0040]

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(Preparation of Dye Dispersion) To 35 g of ethyl acetate, 0.8 g of the following dye B was added and dissolved by stirring. 85 g of a 6% by weight solution of polyvinyl alcohol (PVA-217) previously dissolved in the solution was added, and the mixture was stirred with a homogenizer for 5 minutes. Thereafter, the ethyl acetate was volatilized by removing the solvent, and finally diluted with water to prepare a dye dispersion.

[0042]

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(Preparation of Solid Base Fine Particle Dispersion) To 26 g of the following solid base, polyvinyl alcohol (PVA-
215) 234 g of a 2 g aqueous solution was added, stirred well, and left as a slurry for 10 hours. Thereafter, an average diameter of 0.
100 ml of 5 mm zirconia beads were prepared, placed in a vessel together with the slurry, and dispersed with a disperser (1 / 4G sand grinder mill: manufactured by IMEX Co., Ltd.) for 5 hours to obtain a solid base fine particle dispersion.

[0044]

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(Preparation of coating solution for back surface) To 38 g of a 10% gelatin solution, 20 g of the previously prepared dye dispersion was added.
20 g of solid base fine particle dispersion and 35 g of water were added to obtain a back surface coating solution.

(Preparation of Coating Solution for Back Surface Protective Layer) The above surfactant A was added in an amount of 0.26 to 10 g of inert gelatin.
g, 0.09 g of Surfactant B, 0.3 g of 1,2- (bisvinylsulfonylacetamido) ethane, Sildex H121 (Spherical silica manufactured by Dokai Chemical Co., average size 12)
μm) and 64 g of water were added to form a back surface protective layer.

(Preparation of Coated Sample) The emulsion layer coating solution-1 prepared above was coated with a photosensitive layer-added dye on a 175 μm polyethylene terephthalate support at a silver amount of 2.2 g / g.
m ^2, and the emulsion surface protective layer coating solution was coated on the emulsion coating layer with a gelatin coating amount of 1.8 g / m 2.
² was applied. After drying, a coating solution for the back surface was applied on the surface opposite to the emulsion layer so that the coating amount of Dye B was 56 mg / m ^2, and a coating solution for the back surface protective layer was further coated on the back surface coating layer. A sample was prepared by coating so that the coating amount was 1.8 g / m ² .

[0048]

As described above in detail, according to the image recording apparatus of the present invention, since the phase changing means for making the laser beam a light beam having a random phase difference is provided, the laser beam having a random phase is used. Scanning exposure can be performed, and generation of interference fringes due to reflection in the recording material can be eliminated.

If the phase varying means is provided so as to be movable in the direction of the optical axis of the laser beam, the degree of coherence can be changed and the contrast of interference fringes can be made inconspicuous. Further, if the phase changing means is provided so as to be movable in a direction substantially orthogonal to the optical axis direction of the laser light, the coherence can be improved and the laser light having sufficient intensity and shape can be focused on the recording material. .

Furthermore, if the movement of the laser light in the direction substantially orthogonal to the optical axis direction is synchronized with the main scanning of the laser light, the cost for the synchronous movement can be minimized. If the phase changing means is ground glass, the phase changing means can be made inexpensive. If the phase variable means includes a fine dispersion in the light transmitting layer, the randomness of the phase transmission characteristics can be easily set.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image exposure unit of an image recording apparatus according to the present invention.

FIG. 2 is an explanatory diagram showing a phase change by a phase variable unit.

FIG. 3 is an explanatory diagram showing a change in each part due to movement of a phase variable unit.

FIG. 4 is an explanatory diagram showing another example of the structure of the phase changing means.

FIG. 5 is a conceptual diagram of an image exposure unit of a conventional image recording apparatus.

FIG. 6 is an explanatory diagram showing an optical path difference generated in a recording material.

[Description of Signs] 30 Image recording device 33 Phase changing means 43 Glass beads (dispersion) 45 Microcapsules (dispersion)

Claims (6)

[Claims] 1. An image recording apparatus for forming a latent image on a recording material by scanning exposure with a laser beam, comprising: a phase varying unit for converting the laser beam into a light beam having a random phase difference. . 2. An image recording apparatus according to claim 1, wherein said phase varying means is provided so as to be movable in the optical axis direction of said laser light near a converging point of said laser light. 3. An image recording apparatus according to claim 1, wherein said phase changing means is provided so as to be movable in a direction substantially orthogonal to an optical axis direction of said laser light near a focal point of said laser light. . 4. The image recording apparatus according to claim 3, wherein the movement of the laser light in a direction substantially orthogonal to the optical axis direction is synchronized with the main scanning of the laser light. 5. The image recording apparatus according to claim 1, wherein said phase changing means is a ground glass. 6. The light transmission layer according to claim 1, wherein said phase changing means includes a fine dispersion in said light transmitting layer.
The image recording apparatus according to any one of the above items.