Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Two or more radiation-sensitive layers containing other than...
Reexamination Certificate
2000-09-15
2003-03-25
Letscher, Geraldine (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Two or more radiation-sensitive layers containing other than...
C430S567000, C430S955000, C430S599000, C430S603000
Reexamination Certificate
active
06537740
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 11-262187, filed Sep. 16, 1999; and No. 2000-163294, filed May 31, 2000, the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
The present invention relates to a high-speed color negative photographic lightsensitive material. The present invention also relates to a lightsensitive material-built-in photographic product with which an exposure mechanism is provided and a high-speed color negative photographic lightsensitive material is built therein. More particularly, the present invention relates to a high-speed color photographic lightsensitive material, especially for photographing, which is highly sensitive and ensures excellent image quality and high color reproduction saturation and which is improved with respect to the fog increase, sensitivity lowering and graininess deterioration experienced with the passage of time during the period from lightsensitive material production to use. The present invention also relates to a lightsensitive material-built-in photographic product with which an exposure mechanism is provided and into which the above color negative photographic lightsensitive material is built.
High-speed lightsensitive materials are in succession put on the market in accordance with the progress of the technology on lightsensitive materials for photography. Expansion of photographing zone by the increase of the sensitivity of lightsensitive material, such as photographing in dark indoor scenes without the use of strobe or photographing of high shutter speed with the use of a telephotographic lens in, for example, sport photographing, is being realized.
A lightsensitive material-built-in photographic product (what is called a lens equipped film) to which an exposure mechanism is provided and into which a color negative photographic lightsensitive material is built, is widely used due to convenience thereof. However, in order to supply it at a low price, the shutter speed and the aperture thereof are often fixed, and even if the product is provided with strobe, its function is often limited. In order to compensate these problems, many of the built-in color negative photographic lightsensitive materials are high-sensitive color negative films.
For attaining the sensitivity increase of lightsensitive material, conventional means in the art to which the present invention pertains is to prepare a high-speed lightsensitive material by combining the method of increasing the size of silver halide emulsion grains with other technology. The increase of the size of silver halide emulsion grains, although enhancing the sensitivity to a certain extent, inevitably leads to a serious drawback such that, as long as the content of silver halide is fixed, the number of silver halide emulsion grains, accordingly the number of development centers, is reduced to thereby cause an extensive graininess deterioration.
With respect to the high-speed color negative lightsensitive material, designs increasing the content of silver halide emulsion grains, namely the silver coating amount, so far as properties such as desilvering at bleach-fix are permitted, have been implemented in order to increase, even if slightly, the number of development centers simultaneously with the increase of the size of silver halide emulsion grains.
However, it is disclosed in Jpn. Pat. Appln. KOKAI Publication No. (hereinafter referred to as JP-A-) 63-226650 that the thus produced lightsensitive material of high speed and high image quality has the following drawback.
That is, the drawback is that there occur deteriorations of photographic performance, such as a fog increase, sensitivity lowering and graininess deterioration, during the period from lightsensitive material production to use. The main cause of these photographic performance deteriorations is the exposure of lightsensitive silver halide emulsion grains to natural radiation, such as &ggr;-rays or cosmic rays, emitted from, for example, building materials and the ground. It is known that the performance of lightsensitive material is deteriorated by X-rays and other high-energy radiation. However, with respect to the high-speed color negative lightsensitive material of 640 or more in ISO speed, it has been found that the performance deterioration even by extremely weak radiation occurring in nature is unexpectedly intense. Countermeasure to this performance deterioration would be provided by the method of cutting radiation with the use of a material whose radiation absorption coefficient is high, such as lead, in a package or storage shed for lightsensitive material, as described in, for example, Research Disclosure No. 25610 (August, 1985). However, the object of completely implementing this method cannot be attained unless a heavy metal such as lead is used in a considerable thickness, so that easy and low price supply to general consumers is almost impossible. JP-A-63-226650 discloses the technology of coping with the performance deterioration due to natural radiation by reducing the total silver content, or silver content of high-speed layers, in the color negative lightsensitive material. However, the invention of JP-A-63-226650 does not suggest any concrete countermeasures to the above problem that the increase of the size of silver halide emulsion grains in order to attain a sensitivity enhancement inevitably leads to a serious drawback such that, as long as the content of silver halide is fixed, the number of silver halide emulsion grains, accordingly the number of development centers, is reduced to thereby cause an extensive graininess deterioration.
Apart from the above, it is known that a technology for bettering the graininess of high-speed lightsensitive material is provided by employing silver halide grains whose aspect ratio has been increased, as disclosed in, for example, U.S. Pat. No. 4,434,226.
As a result of the inventors' investigations, it has been found that the invention of employing silver halide grains with high aspect ratio, although being effective in reconciling high sensitivity and graininess, brings about the phenomenon such that, when silver halide grains with an aspect ratio of 8 or more are employed in the color negative lightsensitive material, the development inhibitor released from a DIR coupler is excessively trapped because of the large surface area thereof as compared with that of conventional silver halide grains to thereby suppress the exertion of an interlayer effect. It has further been found that, as a consequence, there occurs an extreme lowering of color reproduction saturation, which is a serious problem to the color negative lightsensitive material.
From the viewpoint that the silver coating amount of high-speed emulsion layer is increased for bettering the graininess and that, the greater the size of grains used in the high-speed emulsion layer, the greater the increase of surface area by rendering the aspect ratio 8 or more, the inventors have also found that the above problem of lowering of color reproduction saturation is more serious when grains with an aspect ratio of 8 or more are employed in the high-speed emulsion layer.
Furthermore, in recent years, it has been recognized that using a selenium sensitizer in combination with a gold sensitizer and a sulfur sensitizer is preferable for increasing the sensitivity of silver halide emulsion. As a result of the inventors' investigations, it has been revealed that the use of this technology enables reducing the size of silver halide grains required for realizing identical sensitivity to thereby relieve the suffering of the effect of environmental radiation and that, however, the problem of lowering of color reproduction saturation is still simultaneously brought about thereby.
The above lowering of color reproduction saturation can be compensated for by using a DIR coupler in a large amount. However, this not only causes a cost increase but also l
Aida Shunichi
Omae Norihiro
Birch & Stewart Kolasch & Birch, LLP
Fuji Photo Film Co. , Ltd.
Letscher Geraldine
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