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. 23, 2003
Filed:
Jul. 28, 1999
Yoshinori Muramatsu, Tokyo, JP;
Susumu Kurosawa, Tokyo, JP;
NEC Electronics Corporation, Kawasaki, JP;
Abstract
There is disclosed an image sensor wherein the dispersion in threshold voltages of a transistor constituting a source follower for outputting a signal is compensated. The disclosed image sensor is provided with a coupling capacitor to which an output voltage of a pixel is applied through a transistor and with a transistor of a source follower to read out a voltage at the node S/Hn of the coupling capacitor. The image sensor is so configured that a drain of a transistor is used as a power supply voltage and the transistor is turned on, causing a node S/Hn pre-charged to the power supply voltage, and then the transistor is turned on, causing the voltage of the node S/Hn to be clamped on a sum of a definite voltage and a threshold voltage of the transistor, and further the transistor is turned on, causing an output voltage generated when a pixel is exposed to light to be added to the capacitor, and by restoring the transistor to a power supply voltage of the drain and by again turning the transistor on, an output voltage generated when a pixel is unexposed to light is applied to the capacitor.