1. Field of the Invention
The present invention relates to a method of and apparatus for processing a silver halide-containing photosensitive material for color photography (hereinafter referred to as a "color photosensitive material") which has already been exposed. More particularly, the present invention pertains to a speedy processing method in which silver-removing performance is improved by a large margin. The present invention is also concerned with an apparatus which may effectively be employed to carry out the above-described processing method.
2. Description of the Related Art
Basic steps in processing of general color photosensitive materials are color development and removal of silver. In the color developing step, the exposed Silver halide is reduced to silver by a color developing agent, and the oxidized color developing agent reacts with couplers to give a dye image. The silver thus formed is oxidized by a bleaching agent in the subsequent silver-removing step and further changed into a soluble silver complex by the action of a fixing agent so as to be removed through dissolution.
An actual development processing includes, in addition to the above-described basic steps, a variety of auxiliary steps which are carried out for the purpose of maintaining the required photographic and physical qualities of images or improving the storage stability of images, such as the hardening bath, the stop bath, the image stabilizing bath and the washing bath.
There has recently been a strong demand in the art to speed up the processing, that is, to reduce the time required for the processing, particularly, the time required to complete the silver-removing step, which accounts for nearly a half of the total processing time.
As means for promoting removal of silver, there has been known a bleach-fixing bath (disclosed in the specification of German Patent No. 866,605) which is a monobath consisting of a ferric aminopolycarboxylic acid complex and a thiosulfate. However, in this bleach-fixing bath, a ferric aminopolycarboxylic acid complex, which originally has relatively weak oxidizing power (bleaching power), is put in contact with a thiosulfate, which has reducing power. Accordingly, the bleaching power of this bath may be weakened considerably, so that it is extremely difficult for the bath to satisfactorily remove silver from a color photosensitive material having high sensitivity and a high silver content, and the bleach-fixing bath cannot be put into practical use, disadvantageously.
On the other hand, as means for increasing the bleaching power, there have already been proposed a variety of methods in which various kinds of bleach accelerator are added to the bleaching bath or the bleach-fixing bath or a prebath which is provided at the upstream side of these baths. Examples of such bleach accelerators include a variety of mercapto compounds such as those disclosed in the specifications of U.S. Pat. No. 3,893,895, British Patent No. 138842 and Japanese Patent Laid-Open No. 141623/1978, compounds having a disulfide linkage such as those disclosed in the specification of Japanese Patent Laid-Open No. 95630/1978, thiazolidine derivatives such as those disclosed in the specification of Japanese Patent Publication No. 9854/1978, isothiourea derivatives such as those disclosed in the specification of Japanese Patent Laid-Open No. 94927/1978, thiourea derivatives such as those disclosed in the specifications of Japanese Patent Publication Nos. 8506/1970 and 26586/1974, thioamide compounds such as those disclosed in the specification of Japanese Patent Laid-Open No. 42349/1974, and dithiocarbamates such as those disclosed in the specification of Japanese Patent Laid-Open No. 26506/1980.
However, addition of these bleach accelerators into the bleaching bath, the bleach-fixing bath or a prebath provided at the upstream side of these baths provides no satisfactory increase in the speed of processing, and further improvement is therefore demanded.
In order to overcome these disadvantages, the present inventors have already proposed methods in which a bath having bleaching power is provided at the upstream side of a bath having a bleach-fixing power (see Japanese Patent Nos. 198197/1984 and 198198/1984),laid open on Apr. 17, 1986 as Japanese Patent Laid-Open Nos. 75352/1986 and 75353/1986, respectively. The time required for processing in the bleaching bath in the proposed method wherein removal of silver is carried out in two baths, that is, the bleaching bath and the bleach-fixing bath, can be set so as to be shorter than that in the conventional method wherein removal of silver is effected by combination of the bleaching bath and the fixing bath. However, since the time required for processing in the bleach-fixing bath depends upon the time required for completion of the fixing processing carried out to change the oxidized silver into a soluble silver halide, the processing time for the bleach-fixing bath must be set so as to be considerably longer than the time required for processing in the fixing bath in the method wherein removal of silver is effected by combination of the bleaching bath and the fixing bath.
USPTO Backgrounds
USPTO Backgrounds