Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Silver compound sensitizer containing
Reexamination Certificate
2000-09-12
2003-04-29
Baxter, Janet (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Silver compound sensitizer containing
C430S569000
Reexamination Certificate
active
06555308
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a silver halide emulsion having such characteristic as high sensitivity and high contrast, which are suitable for use for shooting. The present invention also relates to a silver halide color photographic light-sensitive material using the emulsion. Further, the present invention relates to an easy to practice and rapid method for forming a color image by using the light-sensitive material.
BACKGROUND OF THE INVENTION
Owing to recent remarkable development of photographic light-sensitive materials utilizing silver halides—silver halide photography system, high-quality color images are now easily available. In recent years, the process of color photography ordinarily utilized has made remarkable progress, and large-scale, centralized color laboratories, in which a large quantity of color prints are produced high-efficiently, and the so-called mini labs, which are installed in shops and are designed to use compact and simple printer-processors, have spread widely. Therefore, anyone can enjoy color photography easily.
In addition, recently, a new-concept APS system, which uses a color negative film capable of recording various information as magnetic records by utilizing a support coated with a magnetic material, has been introduced into the market. This system proposes simplicity in handling films and photographic pleasure, such as capability to change the print size by recording information at the time photographs are taken. In addition, this system proposes a tool for compiling or processing images by reading out image information from a processed negative film by means of a simple scanner. Such methods enable high-quality image information of silver salt photographs to be digitized easily, and they are making the use of the image information commonplace beyond the traditional scope of enjoyment as photographs.
On the other hand, so-called digital still cameras utilizing a CCD as an imaging element are making rapid progress. Cameras for amateurs which are mounted with a CCD element having millions or more of pixels have been put on the market for the past several years to obtain image qualities close to those of photographs. These digital still cameras save a step of developing the film taken, in contrast to usual color photographic systems, and they can produce directly digitized image information. Therefore, it can be made easy to confirm the image directly on a liquid crystal monitor when taking a photograph and to make use of the resulting digital information variously. The image information can be transferred to a printer to make a print readily, it can be variously processed using a personal computer, and it makes image transfer through an internet easy. Along with recent progresses in high density CCDs and in the abilities of equipment treating massive digital data, high quality images worth being appreciated as a photograph have come to be available. Discussion has been made on the possibilities of these digital still cameras being substituted for general photographing means.
In this situation, it is desired to further investigate the high sensitivity and high latitude possessed by silver halide light-sensitive materials with the view of further developing a silver salt photographic system in opposition to a digital still camera system. Although the performance of CCDs used as imaging elements of a digital still camera have been improved remarkably, there is a limitation on the provision of high sensitivity while increasing pixels in elements having a limited size. Also, it is basically difficult to impart high latitude under the restrictions imposed on an inexpensive and simple camera system. Hence, if silver halide light-sensitive materials with higher sensitivity and latitude are attained and mounted on inexpensive and readily handlable products, e.g., films with a lens, a system attractive to customers will be provided.
High sensitization of the silver halide light-sensitive material can be generally attained by increasing the grain size of silver halide grains used as photocells (photosensors). However, this poses the problem of impaired granularity (graininess) as the grain size increases. As measures to increase the sensitivity without impairing the granularity, the use of an emulsion comprising tabular grains with a grain thickness smaller for the projected diameter of a grain (the diameter of a circle equivalent to the projected area of a grain) is disclosed in, for instance, the specifications of U.S. Pat. Nos. 4,434,226 and 4,439,520. In the descriptions of photographic emulsion grains, the value calculated by dividing the projected diameter of a grain by the thickness of the grain, which value is called as an aspect ratio, is used. These specifications describe the fact that grains with a high aspect ratio exhibit better sensitivity/graininess ratio than those having low aspect ratios. In the case of comparing grains having the same grain projected diameter, it is considered that by increasing the aspect ratio, the number of grains can be increased, whereby the granularity can be improved even if the amount of silver to be applied is the same.
However, it has been clarified that if the aspect ratio of grains is increased and the thickness of the grain is designed to be thin, it is hard to obtain high sensitivity and a deterioration of the contrast is further caused by a reduction in the maximum color density.
Such a phenomenon, although the way of its appearance differs depending upon the composition and size of emulsion grains, generally starts to appear as a problem when the thickness of a grain is 0.2 &mgr;m or less and becomes significant when the thickness of a grain is 0.15 &mgr;m or less. Various techniques have been reported as attempts to solve this problem. Examples of these techniques may include a technique in which an epitaxial microcrystalline portion having a different halogen composition is formed on the external surface of a grain, especially at the top thereof or such a portion is doped with a 6-cyano iron group complex, as disclosed in the specifications of U.S. Pat. Nos. 5,536,632 and 5,576,168. However, it has been confirmed that the use of these techniques is insufficient although an improvement in the sensitivity is observed and a reduction in the contrast is not improved occasionally.
In the meanwhile, it is an urgent problem to make it possible to carry out the developing step, which is a weak point of the silver halide light-sensitive material, more easily and rapidly. The strength of the digital still camera lies, after all, in the point that liquid development processing is not required. On the contrary, the development processing of the silver halide light-sensitive material needs private treating equipment and careful control and is hence utilized only in limited bases at present. This reason is as follows. The first reason for this is that expertise and skilled operation are necessary due to the requirement of strict control of the composition and the temperature of the solutions in processing baths for the above-mentioned procedure of color development, bleaching and fixation. The second reason is that equipment to be used exclusively for the developing process is often required, due to substances, contained in the processing solutions, such as color-developing agents and bleaching agents comprising an iron chelate compound and others the discharge of which is regulated from the standpoint of environmental protection. The third reason is that the currently available systems do not satisfactorily fulfill the requirement for rapid reproduction of recorded images, because the above-mentioned development processes still take time, although this time has been shortened with recent advances in technology.
In view of these aspects, many improved technologies have been proposed. For example, IS & T's 48th Annual Conference Proceedings, pp.180, disclose a system in which the dye formed in the developing reaction is transferred to a mordant layer and thereafter a light-sensi
Asami Masahiro
Inaba Tadashi
Sato Tadanobu
Baxter Janet
Fuji Photo Film Co. , Ltd.
Walke Amanda C.
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