Ultrathin tabular grain emulsions with dopants at selected locations
US5536632A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 15, 1995 |
| Grant date | Jul 16, 1996 |
| Priority date | — |
| Expiry date | May 15, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03C1/46
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A chemically and spectrally sensitized ultrathin tabular grain emulsion is disclosed including tabular grains (a) having {111} major faces, (b) containing greater than 70 mole percent bromide, based on silver, (c) accounting for greater than 90 percent of total grain projected area, (d) exhibiting an average equivalent circular diameter of at least 0.7 .mu.m, and (e) exhibiting an average thickness of less than 0.07 .mu.m. Improved sensitivity is observed when the surface chemical sensitization sites include silver halide protrusions of a face centered cubic crystal lattice structure forming epitaxial junctions with the tabular grains and having a higher overall solubility than at least that portion of the tabular grains forming epitaxial junctions with the protrusions and a sensitivity enhancing combination of dopants are contained in the silver halide grains including a first sensitivity enhancing dopant capable of providing shallow electron trapping sites and a second sensitivity enhancing selenium dopant. To further enhance sensitivity, one of the sensitivity enhancing dopants is restricted to the tabular grains while the other is restricted to the silver halide epitaxy.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.