Photographic elements including highly uniform silver bromoiodide tabular grain emulsions
US5250403A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 27, 1992 |
| Grant date | Oct 5, 1993 |
| Priority date | — |
| Expiry date | Feb 27, 2012 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03C7/3022
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Novel tabular grain emulsions and a process for their preparation are disclosed in which silver bromoiodide tabular grains account for greater than 97 percent of total grain projected area and the coefficient of variation of the total grain population is less than 25 percent. This is achieved by forming in a first reaction vessel and transporting to a second reaction vessel a population of silver bromide grain nuclei in the form of regular octahedra having an equivalent circular diameter of less than 40 nanometers and a coefficient of variation of less than 50 percent and in the second reaction vessel converting the grain nuclei into a grain population containing parallel twin planes in more than 90 percent of the grains, so that upon further growth silver bromoiodide tabular grains of desired properties can be realized. A photographic element is disclosed comprised of a support, a first silver halide emulsion layer responsive to minus blue (500 to 700 nm) light and a second silver halide emulsion layer positioned to overlie the first emulsion layer. In the second emulsion layer greater than 97 percent of the total projected area of grains having an equivalent circular diameter of …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.