Photographic process
US4267254A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 1, 1979 |
| Grant date | May 12, 1981 |
| Priority date | — |
| Expiry date | Oct 1, 1999 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03C8/365
- WIPO fieldOrganic fine chemistry
- WIPO sectorChemistry
Abstract
There is described a photograhic method employing a positive-negative diffusion transfer film unit wherein there is formed a positive silver transfer image which may be viewed as a positive transparency without being separated from the developed negative silver image, including an embodiment wherein additive color projection positive images are formed. According to the method, the exposed film unit is developed by contacting the silver halide emulsion layer with a photographic processing composition which comprises an aqueous alkaline solution containing a silver halide developing agent and a silver complexing agent. The silver complexing agent is stable in an alkaline environment, has a melting point less than about 50.degree. C. preferably about 25.degree. C. or less, and the log of the stability constant (.beta.) for a 1:1 complex of the complexing agent with silver is at least about 10.5. The film unit is not washed during the method. According to the method of the invention crystal formation in the transparency is substantially or completely eliminated.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.