Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Silver compound sensitizer containing
Reexamination Certificate
2001-11-27
2004-02-24
Letscher, Geraldine (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Silver compound sensitizer containing
C430S599000, C430S604000, C430S605000
Reexamination Certificate
active
06696236
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a silver halide emulsion and also to a silver halide photographic material using the same. More particularly, it relates to a silver halide emulsion which has an excellent processing speed, which obeys the reciprocity rule at high-intensity exposure and which has an excellent stability between the time of preparation of a coating solution until the time of coating, and also relates to a silver halide photosensitive material using the same. Further, the present invention relates to a silver halide emulsion and a silver halide color photosensitive material using the same which do not exhibit a high intensity reciprocity low failure and which can bring about a high contrast image, even in the case of a digital exposure such as a laser scanning exposure.
2. Description of the Related Art
As the use of digital cameras and personal computers has become widespread in recent years, frequency of use of a silver halide photosensitive material as a material for printing of digital image information too is increasing. As a material for printing of digital image information, an image output material other than a silver halide photosensitive material, typically an ink jet printer paper, has become popular. In order to keep up with such a material, there has been an increasingly strong demand for quicker development processing steps, higher image quality, more stable processing, etc. for silver halide photosensitive materials such as color printing paper.
An exposing means for printing of digital image information on a silver halide photographic material, has been commonly carried out by subjecting a silver halide photosensitive material to a scanning exposure with light using a light beam such as laser beam modified on the basis of the image information. In order to print within a shorter time, it is necessary to make the exposure time for each pixel short and thus there is a demand for a silver halide photographic material showing a favorable response to exposures of shorter time and of higher light intensity. Thus, there is a further demand for a silver halide photosensitive material where the so-called failure of the reciprocity rule at high intensity is less.
In order to prevent failure of the reciprocity rule at high light intensities, a method where a metal compound represented by iridium is doped on substrate grains is well known in the art.
Prevention of the failure of the reciprocity rule of silver halide emulsion using iridium is described, for example, in B. H. Carroll, “Iridium Sensitization: A Literature Review”,
Photographic Science and Engineering
, Vol. 24, No. 6, 1980 and R. S. Eachus, “The Mechanism for Ir
3+
Sensitization” (International Congress on Photographic Science, 1982).
On the other hand, it is also known that a silver halide emulsion to which iridium is added shows a very unfavorable characteristic in that the photographic property (such as sensitivity and gradation) changes in accordance with the time that elapses until the post exposure processing is carried out. The characteristic is described in H. zwicky's, “On the Mechanism of the Sensitivity Increase with Iridium in Silver Halide Emulsions”,
The Journal of Photographic Science
, Vol. 33, pages 201-203, 1985.
Although reciprocity failure a result of high light intensity has been significantly mitigated by the conventional methods, variations in the sensitivity with the changes in the time until the post exposure processing is carried out become significantly large and, therefore, such methods are not practical.
In an attempt to solve the problems of sensitivity variation with changes in the time until the post exposure processing is carried out by preventing reciprocity failure due to high intensities, there is disclosed a method where a metal compound represented by iridium is doped with grains containing high amount of silver halide in a localized silver bromide phase in the U.S. Pat. Nos. 5,391,471, 5,041,599, 5,043,256 and 5,627,020.
Further, in the Japanese Patent Laid-Open No. 7-34103, there is disclosed an art where an iridium compound is introduced into silver halide grains together with formation of a local phase containing a high amount of silver bromide.
Furthermore, in the Japanese Patent Laid-Open No. 11-109534, it is disclosed that, in a silver halide emulsion having a local silver bromide phase containing an iridium compound near silver halide grains, a high density area of the iridium compound is formed in the inner side of the local silver bromide phase whereby the above-mentioned problem is improved.
However, as a result of the investigation of the present inventors, improvement of the emulsion obtained by the above-mentioned art is not sufficient and, especially when the temperature at the exposure is low, stability of sensitivity and gradation with respect to variations in the time until the post exposure processing is carried out has been found to be still insufficient and there has been a demand for the development of the means for solving this problem.
In addition, it has been known that an iridium-doped silver chloride emulsion causes a latent image sensitization in a short period of time after exposure. For example, Japanese Patent Publication No. 7-34103 discloses that a localized phase (site) which has a high silver bromide content in which iridium is doped so that problems in the latent image sensitization can be solved. The silver halide emulsion prepared by this method can provide a high sensitivity and high contrast of an image even in a relatively high illumination intensity exposure at about {fraction (1/100)} second, and does not cause problems in the latent image sensitization. However, it has been found that when a high sensitivity is required at an extremely high illumination intensity exposure to the extent about 1 &mgr;second, which is required for a digital exposure method using a laser scanning exposure, a high contrast of an image cannot be obtained.
U.S. Pat. No. 5,691,119 discloses a method for preparing an emulsion containing silver halide grains having a localized phase (site) having a high content of silver bromide, and describes that the emulsion brings about a high contrast under a high illumination intensity. However, there are drawbacks that such effect is not satisfactory and the reproducibility of performances of the emulsions prepared repeatedly by this method is poor.
U.S. Pat. Nos. 5,783,373 and 5,783,378 disclose that a high illumination reciprocity law failure is reduced and a high contrast can be obtained by the use of at least three types of dopants. However, the high contrast is obtained by using the dopants having desensitizing and contrast enhancement functions, so that this method is not compatible with the sensitivity enhancement.
U.S. Pat. Nos. 5,726,005 and 5,736,310 disclose that an emulsion containing grains which have a maximum concentration of iodine on the surface of silver chloride emulsion to obtain an emulsion having a high sensitivity and a less high illumination reciprocity low failure. However, a higher sensitivity can be obtained with a higher illumination intensity, but the gradation of this emulsion is extremely low so that it is not suitable for digital exposure having a limited dynamic range of light amount.
As described above, a silver halide color photographic photosensitive material (silver halide emulsion) which can provide a high sensitivity without a high illumination intensity reciprocity failure and with a less latent image sensitization and which is capable of forming a high contrast image has not been yet obtained.
SUMMARY OF THE INVENTION
The invention is to solve the above-mentioned conventional problems and to achieve the following object.
Thus, the present invention is to provide a silver halide emulsion showing excellent processing speed, little reciprocity failure upon a high-intensity exposure and little change in sensitivity when the time from exposure until development changes, and which is unaffected by tem
Ishizaka Tatsuya
Nakahira Shinichi
Fuji Photo Film Co. , Ltd.
Letscher Geraldine
LandOfFree
Silver halide emulsion and silver halide photosensitive... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Silver halide emulsion and silver halide photosensitive..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Silver halide emulsion and silver halide photosensitive... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3280154