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:
Jul. 22, 1997
Filed:
Mar. 21, 1995
Kazuo Konuma, Tokyo, JP;
NEC Corporation, Tokyo, JP;
Abstract
A light receiving device includes, in addition to a photodiode and a reset element, a comparator formed by a first and a second MOS transistor and a counter. The comparator compares an output potential of the photodiode applied to a gate electrode of the first MOS transistor with a threshold potential externally applied to a gate electrode of the second MOS transistor. The counter counts a time duration from a point of time when the photodiode is reset by the switching element to a point of time at which the output potential of the photodiode exceeds the threshold potential, and outputs the time duration in a numeral value corresponding to the quantity of light incident on the photodiode. The required light sensitivity can be maintained even when the quantity of light is either large or small. Also, non-destructive reading can be carried out.