The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 30, 1997
Filed:
Oct. 27, 1995
Hirokazu Saito, Kanagawa, JP;
Sugihiko Tada, Shizuoka, JP;
Fuji Photo Film Co., Ltd., Kanagawa, JP;
Abstract
A method of producing a silver halide photographic emulsion in which a silver ion concentration in precipitation of a silver halide emulsion in a precipitation bath is controlled, wherein a precipitation bath in which stirring is conducted rapidly and uniformly, and crystal formation and crystal growth are uniformly performed is used, the method comprises the steps of: in a start period of precipitation, quantitavely adding a silver nitrate solution and a halogen salt solution at a constant ratio flow rate; when an E.sub.Ag value reaches a designated E.sub.Ag value region in the vicinity of a preset target E.sub.Ag value, starting a control of an adding rate of the halogen salt solution by using a controller which has an operation period equal to or shorter than 1 sec.; and after holding a tuning parameter of a proportional, integral and differential (PID) action controller to a minimum response level, conducting a control in which the tuning parameter is switched to an optimum control tuning parameter which corresponds to the preset target value and a solute rate of silver/halogen ions to be added.