Patents Represented by Law Firm Fotzpatrick, Cella, Harper & Scinto
  • Patent number: 4496832
    Abstract: A focusing state discriminating system of the invention discriminates the focusing state of an image forming optical system, based on signals F1, F2 and F3 representing image formation states of images formed at first, second and third positions of the optical system which substantially correspond to positions slightly in front of, coincident with and slightly behind the predetermined focal plane of the image forming optical system. The operation for discrimination in this system includes at least a comparison of .vertline.F1-F3.vertline. and K(F1+F2+F3), where K is a constant.
    Type: Grant
    Filed: October 9, 1981
    Date of Patent: January 29, 1985
    Assignee: Canon Kabushiki Kaisha
    Inventors: Shinji Sakai, Nobuhiko Shinoda, Takao Kinoshita, Kazuya Hosoe, Takashi Kawabata