JPH0650374B2 - Direct positive image formation method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for forming a direct positive image, and more specifically, a direct positive type halogen capable of obtaining a direct positive image by a surface development process involving overall exposure after image exposure. The present invention relates to a method for forming a direct positive image using a silver halide photographic light-sensitive material.

BACKGROUND OF THE INVENTION It is well known that a silver halide photographic light-sensitive material can generally be used to directly form a positive image without requiring an intermediate processing step or a negative photographic image.

Conventionally known methods for forming a positive image using a direct positive type silver halide photographic light-sensitive material can be classified into two types mainly in consideration of practical usefulness, except for special ones.

One type is to obtain a positive image after development by destroying fog nuclei (latent image) in an exposed area by using a fogged silver halide emulsion and utilizing solarization or Herschel effect. .

The other type is a method in which an internal latent image type silver halide emulsion which has not been fogged in advance is used and surface development is carried out after image exposure or after fog treatment or while fog treatment is carried out to obtain a dry image.

The above-mentioned internal latent image type silver halide photographic emulsion refers to a silver halide photographic emulsion in which a silver halide grain has a photosensitive nucleus mainly inside and a latent image is formed inside the grain by exposure.

This latter type method is generally more sensitive than the former type method and is suitable for applications requiring high sensitivity, and the present invention relates to this latter type.

Various techniques have been known so far in this technical field. For example, U.S. Patent Nos. 2,592,250 and 2,466,9
No. 57, No. 2,497,875, No. 2,588,982, No. 3,761,26
Mainly those described in No. 6, No. 3,761,276, No. 3,796,577 and British Patent No. 1,151,363 are cited.

By using these known methods, a photographic light-sensitive material having a relatively high sensitivity as a direct positive type can be produced.

Although it is hard to say that a clear explanation has been given so far regarding the details of the mechanism of forming a direct positive image, for example, Mies and James, "The Theory of the
Photographic Process "(The Theory of the P
hotographic Process) Third Edition The process of forming a positive image can be understood to some extent by the "desensitizing effect of an internal latent image" as discussed on page 161.

That is, the fog nuclei are selectively generated only on the surface of the unexposed silver halide grains by the surface desensitizing action based on the so-called internal latent image generated inside the silver halide grains by the first image exposure, It is considered that a photographic image is formed in the unexposed area by the development of No.

As described above, as means for selectively generating fog nuclei, a method called fog by exposing the entire surface of the photosensitive layer to light, and a fog agent called chemical fog are usually used. A method of applying a rash using a drug is known.

Among these methods, the chemical fogging method has a severe condition that the effect of the fog agent can be obtained only at a high pH of 12 or more, so that the fog agent is apt to deteriorate due to air oxidation, and therefore the fog effect is remarkably increased. It has the drawback of decreasing.

Further, the optical fogging method is practically convenient because it does not have the above-mentioned harsh conditions, but it remains a technical problem in order to be used for various purposes in a wide range of photographic fields. That is, since the photo-fog method is based on the formation of fog nuclei by photo-decomposition of silver halide, its appropriate exposure illuminance and exposure amount differ depending on the type and characteristics of the silver halide used.

For example, Japanese Patent Publication No. 45-12709 discloses a method of uniformly exposing the entire surface with light of low illuminance.

According to the document, a good positive image having a high maximum density and a low minimum density can be obtained by exposing the entire surface with low illuminance.

Further, as a result of examination by the present inventors, in order to obtain a relatively good positive image, it is necessary to perform fog exposure with a relatively low illuminance within a certain limited range, and an illuminance lower than this. Does not provide a sufficient maximum image density even with sufficient exposure, and at higher illuminance, the maximum density decreases in proportion to the illuminance, and the minimum density also increases. It turned out that there is a phenomenon called.

Therefore, it is desirable that the illuminance and time for uniform exposure on the entire surface are appropriately changed depending on the internal latent image type silver halide photographic light-sensitive material, the development processing conditions, the type of light source used, etc., so as to obtain the best positive image. .

Further, a soft positive image can be formed by using an internal latent image type direct positive photosensitive material. In this case, it is well known to use an emulsion containing two or more kinds of internal latent image type silver halide grains having different average grain sizes in order to impart a soft image.

However, between the internal latent image type silver halide grains having different average grain sizes, not only the sensitivity at the time of photographing, but also
Since the sensitivity for whole surface exposure is also different, the optimum conditions for whole surface exposure are different, and when performing whole surface exposure with a constant illuminance, the photographic characteristics, especially the maximum density, are very likely to fluctuate with respect to fluctuations in illuminance due to fog exposure. It turned out to have.

That is, an internal latent image type silver halide photographic light-sensitive material containing two or more kinds of silver halide grains having different average particle diameters is subjected to whole surface exposure and developed to obtain a high density portion of a positive image. However, due to local non-uniformity of illuminance on the photosensitive surface during light fog or temporal change of illuminance of the light source, uniform and constant light fog exposure is not always performed, and the density easily fluctuates and a stable image is obtained. It turns out that there is a drawback that you cannot do it.

The present inventors have completed the present invention as a result of intensive studies to solve such a drawback.

[Object of the Invention] An object of the present invention is to use a direct positive type silver halide photographic light-sensitive material containing an internal latent image type silver halide grain, which is stable against illuminance fluctuation during whole surface exposure and is excellent. Another object of the present invention is to provide a method for directly forming a positive image, which is capable of obtaining a positive image.

[Constitution of the Invention] The above object of the present invention is to form a direct positive type silver halide photographic light-sensitive material having at least one silver halide photographic emulsion layer containing an internal latent image type silver halide grain which has not been fogged in advance. In the method of forming a direct positive image in which a positive image is obtained by exposing the whole surface after exposure, prior to the development processing or during the development processing step, the internal latent image type silver halide grains have different average particle sizes. It consists of at least two kinds, and when giving the whole surface exposure,
It was achieved by a method of forming a direct positive image in which the illuminance is continuously or stepwise increased.

[Specific Structure of the Invention] In the present invention, the light irradiation conditions (exposure pattern, exposure intensity, exposure amount) at the time of overall exposure can be appropriately determined depending on the purpose and performance of each direct positive type silver halide photographic light-sensitive material to be used. be able to.

Further, in the whole surface exposure of the present invention, as a method of applying the illuminance continuously or stepwise, the optimum exposure pattern may be slightly different depending on the purpose and performance of the direct positive type silver halide photographic light-sensitive material. There is, for example, the first
As shown in Figures (a) and (b), not only a simple continuous increase or gradual increase in illuminance but also the illuminance from the start of exposure to the point of maximum exposure as shown in Figure 1 (c). Even an exposure method in which the change pattern of increase and decrease of is complicated is included.
The present invention also includes an intermittent exposure pattern as shown in FIG. This is because, as long as the variation connecting the maximum exposure illuminances in the individual intermittent exposure areas takes the same locus as in the case of continuous exposure in the present invention, the effect of the present invention is essentially the same.

In the present invention, the adjustment of the light fog illuminance may change the luminous intensity of the light source, various color temperature conversion filters under a constant light source, using filters such as a color correction filter, the distance between the light-sensitive material and the light source, This can be advantageously performed by utilizing the angle between the light-sensitive material and the light source. Moreover, in the present invention,
By the method described in 59-870521, the entire surface exposure can be more advantageously performed.

The light fogging method of the present invention is intended only to artificially adjust the illuminance, and when continuous exposure is performed with a single light source, the exposure amount of the light source such as a flash bulb or a strobe flash with a short exposure time can be adjusted. The optical fogging method using the gradual increase is not included in the gist of the present invention and is excluded from the present invention. However, when intermittent fogging is performed by the method of the present invention, the use of flashing of a strobe, a flash bulb, or other light source is not limited to this, and is included in the present invention. The present invention can be advantageously implemented by combining two or more kinds of light sources having different spectral distributions and color temperatures.

In the present invention, the light irradiation conditions for light fog differ depending on the photosensitive material used, but at the initial stage of light fog, light of 0.001 to 200 Lux and maximum illuminance of 0.1 to 20000 Lux can be used.

Further, in the present invention, it is most preferable that the maximum light irradiation during the entire exposure period is performed after the exposure is started and at least 1/3 or more of the total exposure time has elapsed.

Further, the ratio of the initial minimum exposure illuminance to the latter maximum exposure illuminance is preferably 1/3 to 1/500, more preferably 1/1
It is 0 to 1/100.

As the light source for light fog, at least one light source within the photosensitive wavelength range of the photographic light-sensitive material may be used, but in the case of a color photographic light-sensitive material, a wide spectral distribution over the visible light range of 400 nm to 700 nm. It is desirable to use at least one light source having

In the present invention, when performing fog exposure, the whole surface exposure before development means that the whole surface exposure after image exposure is carried out in a processing bath for processing prior to development. If necessary, the processing bath may contain a reducing substance, an alkaline agent, an inhibitor, a desensitizer, and the like.

When the entire surface is exposed during the development process, it is preferable to perform the exposure at the initial stage of development from the viewpoint of shortening the development time. In that case, the exposure is started after the developer has sufficiently penetrated into the emulsion layer. Is advantageous.

In the present invention, at least two types of internal latent image type silver halide grains having different average grain sizes are preferably monodisperse grains. Further, in the present invention, at least two kinds of internal latent image type silver halide grains having different average grain diameters, each grain having an average grain diameter different by 0.1 μm or more is preferable.

In the present invention, the average particle size of the internal latent image type silver halide grains is preferably 0.2 to 1.2 µ, more preferably 0.3 to 1 µ.

The monodisperse internal latent image type silver halide grain of the present invention may be a normal crystal such as a cube, a tetrahedron or an octahedron, may be composed of twins, or may be a mixture thereof. Is preferably a normal crystal.

In the present invention, the monodisperse internal latent image type silver halide grains mean that the weight of silver halide grains contained within a grain size range of ± 20% around the average grain size is the total weight of silver halide grains. It means 60% or more, preferably 70% or more, particularly preferably 80% or more.

Here, the average particle size is the frequency n of particles having a particle size γi.
The grain size γi when the product ni × γi ³ of i and γi ³ becomes maximum is defined.

(3 significant digits, rounding down to the least significant digit are rounded off.) The grain size referred to here is, in the case of spherical silver halide grains, immediately thereafter, or in the case of silver halide grains having a shape other than spherical. Is the diameter when the projected image is converted into a circular image of the same area.

The particle size can be obtained, for example, by magnifying the particles with an electron microscope from 10,000 times to 50,000 times and measuring the particle diameter on the print or the area at the time of projection.
(The number of measured grains is indiscriminately 1000 or more.) In the present invention, two or more grains having different average particle sizes are mixed and coated on a support as the same silver halide layer. Alternatively, they can be coated in multiple layers as separate emulsion layers.

In the present invention, when the direct positive type silver halide photographic light-sensitive material is a color light-sensitive material having, for example, three different color-sensitive layers, at least two kinds of internal latent image-type halogenated materials having different average particle diameters are used. The silver particles are contained in the same color-sensitive layer, and any color-sensitive layer may be used as long as they are in the same color-sensitive layer.

The internal latent image type silver halide emulsion in the present invention is an emulsion having silver halide grains which form a latent image mainly inside the silver halide grains and have most of the photosensitive nucleus inside the grains. Silver halides such as silver bromide, silver chloride, silver chlorobromide, silver iodobromide, silver chloroiodobromide and the like are included.

The internal latent image type silver halide grain of the invention is preferably such that the grain surface is not chemically sensitized, or even if it is sensitized, the amount thereof is slight. In the present invention, the meaning that the grain surface is not pre-fogged means that the emulsion used in the present invention is 35 mgAg on a transparent film support.
It means that the density obtained when the test piece coated so as to have a density of / dm ² is developed with the surface developing solution A described below at 20 ° C. for 10 minutes without being exposed, does not exceed 0.6, preferably 0.4.

(Surface developer A) Metol 2.5 g - 1 by addition of ascorbic acid _{10g NaBO 2 · 4H 2 O 35g} KBr 1g Water The silver halide emulsion used in the present invention, exposing the test piece prepared as above After that, when developed with an internal developer B having the following formulation, a sufficient density is given.

(Internal Developer B) Metol 2 g Sodium sulfite (anhydrous) 90 g Hydroquinone 8 g Sodium carbonate (-hydrate) 52.5 g KBr 5 g KI 0.5 g Water 1 was added. When exposed to a light intensity scale for a certain period of time up to about 1 second and developed with internal developer B at 20 ° C. for 4 minutes, another part of the test piece exposed under the same conditions was used as a surface developer. It exhibits a maximum density of at least 5 times, preferably at least 10 times that obtained when developed at 20 ° C. for 4 minutes in A.

Specifically, for example, conversion type silver halide emulsions described in U.S. Pat.No. 2,592,250, internal chemical sensitizing nuclei or polyvalent nuclei described in U.S. Pat.Nos. 3,761,266 and 3,761,276. Core / shell type silver halide emulsion doped with metal ions, JP-A-50-8524,
No. 50-38525, No. 53-2408, laminated silver halide emulsions described in JP-A-52-156614,
Examples thereof include emulsions described in Japanese Patent Application No. 54-35361.

The silver halide emulsion used in the present invention can be optically sensitized with a commonly used sensitizing dye. A combination of sensitizing dyes used for supersensitization such as an internal latent image type silver halide emulsion and a negative type silver halide emulsion is also useful for the silver halide emulsion used in the present invention. Research Disclosure for the sensitizing dye used in the present invention
(Reseach Disclosure) No. 15162 can be referred to.

The silver halide emulsion used in the present invention contains a stabilizer usually used, for example, a compound having an azaindene ring and a heterocyclic ring having a mercapto, in order to keep the surface sensitivity as low as possible and to give a lower minimum density and more stable properties. Formula compounds (representative examples include 4-hydroxy-6-methyl-1,3,3a, 7-tetrazaindene and 1-phenyl-5-mercaptotetrazole, respectively) can be included.

Others In the silver halide emulsion used in the present invention, as the antifoggant or stabilizer, for example, a mercury compound, a triazole compound, an azaindene compound, a benzothiazolium compound, a zinc compound or the like can be used.

It is optional to add various photographic additives to the silver halide emulsion used in the present invention.

Others In the present invention, as an additive used according to the purpose, examples of the wetting agent include dihydroxyalkane and the like, and examples of the film physical property improving agent include, for example, alkyl acrylate or alkyl metaactylate and acrylic acid or Copolymers with methacrylic acid, styrene-maleic acid copolymers, water-dispersible fine particulate polymer substances obtained by emulsion polymerization of styrene maleic anhydride half alkyl ester copolymers, etc. are suitable and applied. Examples of the auxiliaries include saponin and polyethylene glycol lauryl ether. Other photographic additives include gelatin plasticizers, surfactants, ultraviolet absorbers, pH adjusters, antioxidants, antistatic agents, thickeners, graininess improvers, dyes, moldants, brighteners, and development speeds. The use of regulators, matting agents, etc. is optional.

The internal latent image type silver halide emulsion prepared as described above is
If necessary, it is coated on a support through an undercoat layer, an antihalation layer, a filter layer, etc. to directly obtain a positive type silver halide photographic light-sensitive material.

It is useful to apply the direct positive type silver halide photographic light-sensitive material used in the present invention for color, and in this case, it is preferable to include cyan, magenta and yellow dye image-forming couplers in the silver halide photographic emulsion. . As the coupler, those usually used can be used.

Further, it is useful to use an ultraviolet absorber such as thiazolidone, benzotriazole, acrylonitrile, or a benzophenone compound in order to prevent browning due to an active light source having a short wavelength in a dye image, and particularly, tinupin PS, 32
0, 326, 327, 328 (all manufactured by Ciba Geigy)
The single use or the combined use of is advantageous.

As the support of the direct positive type silver halide photographic light-sensitive material used in the present invention, any support may be used, but as a typical support, a polyethylene terephthalate film, a polycarbonate film, which is optionally subjected to undercoating,
Polystyrene film, cellulose acetate film, baryta paper, polyethylene laminated paper, etc. are included.

For the silver halide emulsion used in the present invention, a gelatin derivative suitable for the purpose can be used in addition to gelatin as a protective colloid or a binder. Examples of suitable gelatin derivatives include acylated gelatin, guanidylated gelatin, carbamylated gelatin, cyanoethanolated gelatin, esterified gelatin and the like.

Further, in the present invention, other hydrophilic binders may be contained depending on the purpose, and as such a suitable binder, in addition to gelatin, colloidal albumin, agar, arabic gum, dextran, alginic acid, acetyl-containing 19 ~
Cellulose derivatives such as cellulose acetate hydrolyzed to 20%, polyacrylamide, imidized polyacrylamide, casein, vinyl alcohol polymers containing urethanecarboxylic acid groups or cyanoacetyl groups such as vinyl alcohol-vinyl aminoacetate copolymer, polyvinyl Emulsion layer containing alcohol, polyvinylpyrrolidone, hydrolyzed polyvinyl acetate, polymer obtained by polymerization of protein or saturated acylated protein and monomer having vinyl group, polyvinylpyridine, polyvinylamine, polyaminoethylmethacrylate, polyethyleneamine, etc. Or an intermediate layer, a protective layer,
It may be added to the constituent layers of the silver halide photographic light-sensitive material such as the filter layer and the backing layer according to the purpose, and the hydrophilic binder may further contain an appropriate plasticizer, lubricant and the like according to the purpose. You can

The constituent layers of the direct positive type silver halide photographic light-sensitive material used in the present invention can be hardened with any appropriate hardener. Examples of these hardeners include chromium salts, zirconium salts, aldehyde compounds such as formaldehyde and mucohalogen acid, halotriazine compounds, polyepoxy compounds, ethyleneimine compounds, vinylsulfone compounds, acryloyl system hardeners and the like. .

Further, the direct positive type silver halide photographic light-sensitive material used in the present invention has various photographic constitutions such as an emulsion layer, a filter layer, an intermediate layer, a protective layer, an undercoat layer, a backcoat layer and an antihalation layer on a support. It is possible to install multiple layers.

In the present invention, the surface developer used for the development treatment is
It means a developer substantially free of a silver halide solvent, and as a developer that can be used in the surface developer, an ordinary silver halide developer, for example, polyhydroxybenzenes such as hydroquinone, Aminophenols, 3-pyrazolidones, ascorbic acid and its derivatives, reductones, phenylenediamines and the like or mixtures thereof are included. Specifically, hydroquinone,
Aminophenol, N-methylaminophenol, 1-
Phenyl-3-pyrazolidone, 1-phenyl-4,4-
Dimethyl-3-pyrazolidone, 1-phenyl-4-methyl-4-hydroxymer-3-pyrazolidone, 1-phenyl-4,4-dihydroxymethyl-3-pyrazolidone, ascorbic acid, N, N-diethyl-p-phenylene Diamine, diethylamino-o-toluidine, 4'-
Amino-3-methyl-N-ethyl-N- (β-methanesulfonamidoethyl) aniline, 4-amino-3-methyl-N-ethyl-N- (β-hydroxyethyl) aniline, 4-amino-3- Methyl-N, N-diethyl-p
-Phenylenediamine, 4-amino-3-methyl-N-
Examples thereof include ethyl-N-β-methoxyethyl-p-phenylenediamine. These developers may be contained in the emulsion in advance so that they act on the silver halide during immersion in a high pH aqueous solution.

Further, the surface developing solution may further contain a specific antifoggant and development inhibitor, or these developing solution additives may be optionally incorporated in the constituent layers of the photographic light-sensitive material. Usually, useful antifoggants include
Benzotriazoles, benzimidazoles, benzothiazoles, benzoxazoles, 1-phenyl-
Heterocyclic thiones such as 5-mercaptotetrazole, aromatic and aliphatic mercapto compounds and the like are included. Further, the developer may contain a development accelerator such as a polyalkylene oxide derivative or a quaternary ammonium salt compound.

The direct positive type silver halide photographic light-sensitive material used in the present invention is effective for various uses such as general black and white, X ray, color, pseudo color, printing, infrared, micro, and silver dye bleaching. And the colloidal transfer method, Rogers U.S. Pat. Nos. 3,087,817 and 3,185,5.
67 and 2,983,606, Weyerts et al., U.S. Pat.No. 3,253,915, Whitemore et al., U.S. Pat.
U.S. Pat. No. 3,227,551 to Bur et al., U.S. Pat. No. 3,227,552 to Whitemore and U.S. Pat.
It can also be applied to a color image transfer method, a color diffusion transfer method, an absorption transfer method and the like as described in Nos. 15,644, 3,415,645 and 3,415,646.

[Examples] The present invention will be described in more detail with reference to specific examples below, but the embodiments of the present invention are not limited thereto.

Example 1 Two types of silver chlorobromide emulsions having different average grain sizes were prepared by the conversion method. An aqueous solution of 1 mol of silver nitrate and an aqueous solution of 1.1 mol of sodium trichloride were simultaneously added at 60 ° C. over 20 minutes, and then an aqueous solution of 1 mol of potassium bromide was promptly added. After the completion of precipitation, the mixture was redispersed in an aqueous gelatin solution to prepare internal latent image type silver chlorobromide grains having an average grain size of 0.6 μ (emulsion 1). Further, silver chlorobromide grains having an average grain size of 0.3 μm were prepared by the same procedure except that the addition time of silver nitrate and sodium chloride was 3 minutes (emulsion 2).

Next, an emulsion prepared by mixing Emulsions 1 and 2 in the following ratio was added to the oil-protected magenta coupler {1
-(2,4,6-Trichlorophenyl) -3- (2-chloro-5-octadecylsuccinimidoanilino) -5
-Pyrazolone} and a hardening agent are added, and the coated silver amount is 5 mg / d.
Samples 1 to 3 were prepared by coating on a resin-coated paper support so as to have m ² .

These samples were subjected to wedge exposure using a sensitometer, fog exposure was performed under the exposure conditions shown below using tungsten light as a light source, and the following processing was performed.

[Fog exposure conditions] (1) Exposure for 10 seconds at a uniform illuminance of 2 lux (exposure amount 20 CMS) and lower illuminance (2) 10 CMS (3)
The exposure amount was changed to 5 CMS (4) 2 CMS.

(5) Exposure for 8 seconds at an illuminance of 0.25 lux, and then immediately for 2 seconds at an illuminance of 9 lux (exposure amount 20 CMS)
And (6) In the same procedure, the illuminance ratio was not changed and only the illuminance was lowered to change the exposure amount to 10 CMS (7) 5 CMS (8) 2 CMS.

[Processing conditions] Color development (38 ° C., 2 minutes 30 seconds, light fog was performed for 10 seconds after immersion in a developing solution) Bleach fixing (38 ° C., 1 minute 30 seconds) Washing with water (38 ° C., 1 minute 30 seconds) [Color developer composition] It is composed of an aqueous solution of chemicals having the following types and concentrations (g /).

Potassium carbonate 28.9 Potassium sulfite 2.6 Sodium bromide 0.26 Benzyl alcohol 12.8 Ethylene glycol 3.4 Hydroxylamine sulfate 2.6 Diaminopropanol tetraacetic acid 0.09 Sodium chloride 3.2 Nitrilotriacetic acid 0.4 3-Methyl-4-amino-N-ethyl-N- (β-methane Sulfonamidoethyl) -aniline sulfate
5.0 pH (adjusted with potassium hydroxide) 10.40 [Composition of bleach-fixing solution] Consists of an aqueous solution of the following types and concentrations (g /) of chemicals.

Ammonium thiosulfate 110 Sodium hydrogensulfite 10 Ethylenediaminetetraacetic acid Iron ammonium 60 Ethylenediaminetetraacetic acid 2 Ammonium 5 Bisthiourea 2 pH (adjusted with ammonia water) 6.5 The maximum and minimum concentrations of each sample obtained by the above treatment are shown in Table-1. It was shown to.

From the results in Table 1, it can be seen that by applying the optical fog by the method of the present invention, a good positive image can be obtained regardless of which mixed emulsion is used. That is, when the fog exposure amount (or exposure illuminance) changes under the comparative fog exposure conditions (1) to (4), the image density largely fluctuates and the stability is poor. On the other hand, under the fog exposure conditions of the present invention, that is, (5) to (8), the density fluctuation of the positive image is small even if the fog exposure amount changes, and the stability is much improved.

Example 2 Core / shell type silver bromide emulsions having different average grain sizes were prepared by the double mixing method. An aqueous solution of 1 mol of silver nitrate and potassium bromide was slowly added simultaneously at 60 ° C. with vigorous stirring and mixed to prepare cubic silver bromide particles having an average particle size of 0.15 μm. To this, 15 mg of sodium thiosulfate and 15 mg of chloroauric acid were added per 1 mol of silver, and the mixture was chemically ripened at 60 ° C. for 90 minutes. Then, the chemically sensitized silver bromide grain was used as a core, and silver nitrate and bromide were further added. An aqueous solution of potassium was added to finally grow the silver bromide grains having a cubic core / shell structure having an average grain size of 0.2μ. Further, the surface was sensitized by chemical ripening with 2 mg of sodium thiosulfate and chloroauric acid per 1 mol of silver at 60 ° C. for 30 minutes to prepare an internal latent image type core / shell type silver bromide emulsion (Emulsion 3). ).

Core / shell type silver bromide emulsions having different grain sizes were prepared by substantially the same procedure as described above. That is, 0.3 μm of silver bromide core particles was prepared, and sodium thiosulfate (10 mg / silver 1
Mol) and chloroauric acid (10 mg / silver 1 mol) to chemically sensitize them, and then grow the grains with silver bromide to form cubic core / shell type silver bromide grains having an average grain size of 0.4 μ. Got
Then, the surface was sensitized with sodium thiosulfate (2 mg / silver 1 mol) and chloroauric acid (2 mg / silver 1 mol) to prepare an internal latent image type silver bromide emulsion (emulsion 4).

Next, the following sensitizing dye [I] and cyan coupler [II] were added to an emulsion prepared by mixing Emulsions 3 and 4 in an equal amount, and a hardening agent was further added to give a coated silver amount of 5 mg / dm ² . Sample-4 was prepared by coating the above on a resin-coated paper support.

Sample-4 was subjected to wedge exposure and processed under the same processing conditions as in Example 1. However, light fog was performed using a fluorescent lamp for color evaluation under the following exposure conditions.

[Fog exposure condition] (a-1); exposure with uniform illuminance of 3 lux for 10 seconds (exposure amount 30 CMS) (a-2);
Exposure with MS (a-3); Lower illuminance under the conditions of (a-1), and
Exposure with MS (a-4); Decrease the illuminance under the condition of (a-1), 8CM
Exposure with S (a-5); Lower illuminance under the condition of (a-1), and
Exposure with S (b-1); After 5 seconds of exposure with 1 lux of light, immediately 3
Exposed for 3 seconds with the light of looks, and immediately with light of 8 looks for 2
Exposure for 30 seconds (exposure amount 30 CMS) (b-2); 20 under the condition of (b-1) without changing the illuminance ratio.
Exposure with CMS (b-3); 15 without changing the illuminance ratio under the conditions of (b-1)
Exposure by CMS (b-4); 8C without changing the illuminance ratio under the condition of (b-1)
Exposure with MS (b-5); 4C without changing illuminance ratio under the condition of (b-1)
Exposure with MS (c-1); after exposure with light of 2 lux for 9 seconds, immediately 1
2 seconds of light exposure for 1 second, (exposure amount 30 CMS) (c-2); 20 without changing the illuminance ratio under the conditions of (c-1)
Exposure with CMS (c-3); 15 without changing the illuminance ratio under the conditions of (c-1)
Exposure with CMS (c-4); 8C without changing the illuminance ratio under the conditions of (c-1)
Exposure with MS (c-5); 4C without changing the illuminance ratio under the condition of (c-1)
Exposure with MS (d-1); 0.6 second light exposure for 9 seconds, then immediately 2
1 second exposure with 4.6 lux light, (exposure amount 30 CMS) (d-2); 20 under the condition of (d-1) without changing the illuminance ratio.
Exposure by CMS (d-3); 15 without changing the illuminance ratio under the condition of (d-1)
Exposure with CMS (d-4); 8C without changing the illuminance ratio under the condition of (d-1)
Exposure with MS (d-5); 4C without changing the illuminance ratio under the condition of (d-1)
Exposure with MS (e-1); 0.5 lux light for 4 seconds, dark for 3 seconds, 8 lux light for 1 second, 1 again
It was dark for 2 seconds and exposed for 1 second with a light of 20 lux (exposure amount 30 CMS). (E-2); 20) without changing the illuminance ratio under the conditions of (e-1).
Exposure by CMS (e-3); 15 without changing the illuminance ratio under the conditions of (e-1)
Exposure with CMS (e-4); 8C without changing the illuminance ratio under the conditions of (e-1)
Exposure with MS (e-5); 4C without changing illuminance ratio under the condition of (e-1)
Exposure with MS The maximum and minimum densities of the samples obtained by the above treatment are shown in Table-2.

From the results shown in Table 2, it can be seen that a good positive image can be obtained by performing light fog exposure by the method of the present invention. That is, when the fog exposure amount fluctuates, the image density fluctuations are smaller and the stability is much better under the fog exposure conditions b, c, d, and e of the present invention than under the comparative fog exposure condition a. .

[Brief description of drawings]

FIGS. 1 (a) to 1 (d) show examples of illuminance changes in overall exposure in the method of the present invention, which are shown as exposure patterns of various shapes.

Claims (1)

[Claims] 1. A direct positive type silver halide photographic light-sensitive material having at least one silver halide emulsion layer containing an internal latent image type silver halide grain which has not been fogged in advance, and is subjected to imagewise exposure, followed by development processing. Alternatively, in the method of forming a direct positive image in which a positive image is obtained by exposing the entire surface during the development processing step, the internal latent image type silver halide grains are composed of at least two kinds having different average grain sizes, A method for forming a direct positive image, characterized in that, when the whole surface exposure is applied, the irradiation is performed while continuously or stepwise increasing the illuminance.