Radiation imagery chemistry: process – composition – or product th – Radiation sensitive product – Two or more radiation-sensitive layers containing other than...
Reexamination Certificate
2001-08-24
2003-11-11
Letscher, Geraldine (Department: 1752)
Radiation imagery chemistry: process, composition, or product th
Radiation sensitive product
Two or more radiation-sensitive layers containing other than...
C430S506000, C430S567000
Reexamination Certificate
active
06645710
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2000-256166, filed Aug. 25, 2000, the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a silver halide color photographic light-sensitive material and, more particularly, to a silver halide color photographic light-sensitive material which has high image quality regardless of its high sensitivity, i.e., which has high graininess and high sharpness, and which is also excellent in storage stability.
2. Description of the Related Art
Recently, a film with lens “UTSURUNDESU800” having both high sensitivity and high image quality is put on the market, so the habitual use of silver halide color photographic light-sensitive materials in a high-sensitive region is reliably spreading.
Thus increasing the sensitivity of a film can extend the regions of photography by light-sensitive materials. Examples are photographing using no electronic flash in a dark room, photographing at high shutter speeds using telephoto lenses such as sports photography, and photographing requiring long exposure time such as astronomical photography. This brings about great merits to users. Accordingly, increasing the sensitivity of a film is one eternal subject matter imposed on this industry.
Since increasing the sensitivity was pursued too much on conventional high-speed films, only low-quality films far exceeding the limit of user's patience could be provided. This forced users to choose between the two, i.e., the sensitivity and the image quality. Consequently, users had to choose the image quality rather than the sensitivity.
To increase the sensitivity of a light-sensitive material, the conventional approach in this industry is to increase the size of a silver halide grain as a light-sensitive element and use another sensitivity increasing technology at the same time.
When the grain size of a silver halide is increased, the sensitivity rises to some extent. However, as long as the content of the silver halide is constant, the number of silver halide grains, i.e., the number of development start points inevitably reduces. This largely deteriorates the graininess.
If a light-sensitive material is so designed as to increase the number of silver halide grains per unit area in order to compensate for this drawback as much as possible, the film thickness of a photosensitive layer increases accordingly. Also, the sharpness of the film cannot be well increased owing to, e.g., scattering of incident light induced by the silver halide grains. This makes it very difficult to achieve high graininess and high sharpness at the same time.
In addition, if a light-sensitive material is so designed as to increase the number of silver halide grains per unit area as described above, i.e., if the amount of silver halide coated in the material is increased, as described in Jpn. Pat. Appln. KOKAI Publication No. (hereinafter referred to as JP-A-) 63-226650, the photographic properties deteriorate, e.g., the fog increases, the sensitivity lowers, and the graininess deteriorates, before the light-sensitive material is used after the manufacture.
To solve these problems, improving techniques by which high sensitivity and high image quality coexist have been investigated in this industry.
For example, as an approach to the design of a color light-sensitive material, JP-A-62-17747 discloses a technique which improves the sharpness and the graininess by defining the silver density and dried film thickness of a blue-sensitive silver halide emulsion layer. U.S. Pat. No. 5,322,766 discloses a technique which improves the image quality with a small silver amount by defining the silver amount and film thickness of an image forming unit and the flatness and silver/coupler ratio of silver halide grains.
Also, JP-A-63-226650 described above discloses a technique which improves the image quality, storage stability, and resistance to pressure by defining the total silver content and the silver amount of a highest-sensitivity layer of a color negative light-sensitive material having a specific photographic sensitivity of 800 to 6,400.
Unfortunately, improvements by these techniques were not well satisfactory. That is, the ultimate image quality levels of graininess and sharpness were unsatisfactory in a region where the specific photographic sensitivity was 800 or more. Also, the effects of improving deterioration of the image quality after storage were insufficient.
On the other hand, when the image quality level or that after storage was satisfied at all times, the specific photographic sensitivity became insufficient. Accordingly, no satisfactory prints could be obtained by photographing in a room in which the use of an electronic flash was prohibited.
As described previously, increasing the sensitivity of a film can extend the regions of photography by light-sensitive materials. Hence, the development of a silver halide color photographic light-sensitive material having high sensitivity and high image quality at the same time is particularly being desired lately.
BRIEF SUMMARY OF THE INVENTION
It is an object of the present invention to provide a silver halide color photographic light-sensitive material having high graininess and high sharpness regardless of its high sensitivity, and to provide a silver halide color photographic light-sensitive material which is also excellent in storage stability.
The present inventors made extensive studies and could achieved the above object by the present invention having the following arrangements.
(1) A silver halide color photographic light-sensitive material comprising, on a support, a unit blue-sensitive silver halide emulsion layer, unit green-sensitive silver halide emulsion layer, and unit red-sensitive silver halide emulsion layer, each of which includes not less than two color-sensitive layers differing in sensitivity, wherein tabular grains having an aspect ratio of not less than 5.0 account for not less than 60% of the total projected area of silver halide grains contained in an emulsion layer having the highest sensitivity in each unit color-sensitive layer, and a grain number indicated by equation (I) below is not more than 1.00:
(Grain number)=
A
H
/(
D
c
2
×T
h
) (I)
where
A
H
: a silver coating amount (g/m
2
), as an amount of silver, of a silver halide contained in an emulsion layer having the highest sensitivity
D
c
: an average equivalent-circle diameter (&mgr;m) of silver halide grains contained in an emulsion layer having the highest sensitivity
T
h
: an average thickness (&mgr;m) of silver halide grains contained in an emulsion layer having the highest sensitivity,
if silver halide grains contained in the emulsion layer are a mixture of not less than two types of silver halide emulsion grains having different average equivalent-circle diameters, the grain number is calculated from A
H
, D
c
, and T
h
of emulsion grains, of the not less than two types of emulsion grains, having the largest average equivalent-circle diameter.
(2) The material according to item (1), wherein silver halide grains contained in an emulsion layer having the highest sensitivity in each unit color-sensitive layer are tabular grains which:
(a) have an average silver iodide content of 2 to 10 mol %,
(b) have an average surface silver iodide content of 1 to 4 mol %, and
(c) have not less than 10 dislocation lines per grain.
(3) The material according to item (1) or (2), wherein the total content of silver contained in the light-sensitive material is 3.0 to 8.5 g/m
2
. (4) The material according to one of items (1) to
(3), wherein the specific photographic sensitivity is not less than 1,000.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invent
Nishimura Ryoji
Nozawa Yasushi
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