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:
Sep. 05, 1978
Filed:
Nov. 24, 1976
Applicant:
Inventors:
Masahiro Kawasaki, Tokyo, JP;
Yoshio Sawada, Tokyo, JP;
Assignee:
Asahi Kogaku Kogyo Kabushiki Kaisha, Tokyo, JP;
Primary Examiner:
Int. Cl.
CPC ...
G03B / ; G03B / ;
U.S. Cl.
CPC ...
354 / ; 354 53 ; 354 / ; 354 / ; 356226 ;
Abstract
An analog-to-digital converter circuit for a photographic exposure meter includes a plurality of parallel connected transistors 51, 54, 57 and 60 whose bases are connected to the logarithmic output of a light measuring circuit A. The transistor collectors are driven by constant current sources comprising an equal plurality of transistors 50, 53, 56 and 59 having emitter area ratios of 1:2:4:8, whereby the collector voltages of the transistors represent a digital threshold conversion of the light measuring circuit output.