Photomechanical process needs an image-forning system producing super contrast photographic characteristics (particularly photographic characteristics in which the gamma is at least 10) for good reproduction of continuous gradation or line images by means of dot images.
For this purpose, a hydroquinone developer (or an infectious developer) has been generally used in which the effective concentration of sulfite ions is greatly reduced, usually to not more than 0.1 mol per liter of the developer. This method, however, suffers from a serious problem in that the stability of the developer is poor because of its low sulfite ion concentration and therefore cannot be stored stably for more than 3 days.
U.S. Pat. No. 2,419,975 discloses that a high contrast negative image can be obtained by adding certain hydrazine compounds to a silver halise emulsion However, when super contrast photographic characteristics wherein the gamma is at least 10 are intended to be obtained using the hydrazine compounds disclosed in the above U.S. Pat. No. 2,419,975, it is necessary to use a developer having a pH as high as 12.8. Such strongly alkaline developers having a pH near 13 are liable to be oxidized by air and thus cannot be stored stably or used over long periods of time. Of course, the storage stability can be improved by increasing the amount of sulfite ions added. However, to sufficiently improve the stability of a developer having such a high pH, it is necessary to add a large amount of sulfite. This not only causes contamination of the processing solution, but also produces a serious problem in that the formation of images of high contrast is prevented.
It has therefore been desired to develop an image-forming system which enables the production of a super contrast image using a processing solution with increased stability.
Under such circumstances, U.S. Pat. Nos. 4,224,401, 4,168,977, 4,311,781, 4,272,606, 4,221,857, and 4,243,739 disclose a system whereby a super contrast negative image having a gamma in excess of 10 is formed by processing a surface latent image-type silver halide photographic light-sensitive material with specific hydrazine compounds added thereto with a stable developer containing not less than 0.15 mol/liter of sulfite ions and having a pH of from 11 to 12.3.
This system, however, still has various problems For example, a relatively long processing time is needed to obtain the desired photographic performance (i.e., the developing speed is low), and the photographic characteristics vary considerably depending on the developing time and the developing temperature (i.e., the developing latitude is narrow) Therefore, it has been desired to further improve the system to attain the object that the photographic characteristics of super contrast and high sensitivity characteristic of the system are realized by a rapid processing and further with a broad developing latitude
USPTO Backgrounds
USPTO Backgrounds