Tabular grain emulsions with sensitization enhancements
US5576171A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 15, 1995 |
| Grant date | Nov 19, 1996 |
| Priority date | — |
| Expiry date | May 15, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03C1/08
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A chemically and spectrally sensitized tabular grain emulsion is disclosed including tabular grains (a) having {111} major faces, (b) containing greater than 70 mole percent bromide and at least 0.25 mole percent iodide, 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 (f) exhibiting an average thickness in the range of from less than 0.3 .mu.m to at least 0.07 .mu.m. It has been observed that photographic performance is enhanced when surface chemical sensitization sites include epitaxially deposited silver halide protrusions forming epitaxial junctions with the tabular grains, the protrusions (a) being located on up to 50 percent of the surface area of the tabular grains, (b) having a higher overall solubility than at least that portion of the tabular grains forming epitaxial junction with the protrusions, (c) forming a face centered cubic crystal lattice, and (d) containing a speed enhancing dopant selected to provide shallow electron trapping sites.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.