Process of preparing high chloride {100} tabular grain emulsions
US5879874A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 31, 1997 |
| Grant date | Mar 9, 1999 |
| Priority date | — |
| Expiry date | Oct 31, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03C2200/43
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A process is disclosed for preparing high chloride {100} tabular grain emulsions containing crystal lattice dislocations in peripheral regions of the tabular grains. In the initial step of the process a radiation-sensitive high chloride {100} tabular grain emulsion is produced to provide host grains. Lateral growth lateral growth of the {100} major surfaces of the tabular grains is extended by precipitating a high chloride peripheral region onto the host tabular grains. After the host grains have been provided an iodide ion source compound with a maximum second order reaction rate constant within the dispersing medium of less than 1.times.10.sup.3 mole.sup.-1 sec.sup.-1 is introduced into the host emulsion to release iodide ions for incorporation into the tabular grains at their peripheral edges by chloride ion displacement. In the resulting emulsion 10 or more crystal lattice dislocations extending inwardly from the peripheral edges of the {100} tabular grains are observed. The dislocations in the peripheral and, particularly, corner regions of the tabular grains increase their sensitivity.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.