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:
May. 05, 2015
Filed:
Oct. 14, 2009
Carl Picciotto, Menlo Park, CA (US);
Glen Eric Montgomery, San Jose, CA (US);
Jeffrey Dicarlo, Menlo Park, CA (US);
Carl Picciotto, Menlo Park, CA (US);
Glen Eric Montgomery, San Jose, CA (US);
Jeffrey DiCarlo, Menlo Park, CA (US);
Hewlett-Packard Development Company, L.P., Houston, TX (US);
Abstract
An optical lighting apparatus having a constant luminance with a drive current controlled by a controller unit. A temperature controlled photodetector indirectly monitors the luminance and informs the controller when a change in luminance has occurred so that the controller can make appropriate adjustments to the drive current. Also disclosed is a method of regulating the drive current to a light source to enable the luminance to remain fixed and independent of fluctuations in ambient temperature. A temperature compensated photodetector senses the amount of light reflected off a diffuser lens and feeds back the output to a controller circuit which regulates the drive current to the light source. The lighting apparatus has application in calibrating imaging systems, such as digital cameras, and for scanning devices.