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:
Jun. 24, 1997
Filed:
Jun. 12, 1995
Daniel A Gordon, Cupertino, CA (US);
Mark J Alguard, Palo Alto, CA (US);
Measurex Corporation, Cupertino, CA (US);
Abstract
Disclosed is an apparatus for measuring on-line the color and color-related properties of a moving sheet. Contrast ratio reflectance measurements are made for providing opacity corrections substantially in real time for a full color spectrum. An optical color sensor in accordance with the invention includes a pair of synchronized spectrometers, the first spectrometer being aligned to view a region of the sheet backed with a highly reflective ('white') material and the second spectrometer being aligned to view a region of the sheet backed with a highly absorptive ('black') material. The use of two spectrometers permits substantially simultaneous 'black' and 'white' measurements for a full color spectrum. The optical color sensing system further includes two light sources, a flashlamp and a continuously energized tungsten filament lamp. The color sensor further includes a sheet backing system including a rotatable standard wheel carrying a white standard tile. Provision is made to permit rotation of the standard wheel and to standardize the sensor off-sheet while maintaining isolation of the white standard tile from the paper mill environment. The sheet backing system includes a paper guide plate defining an annular vortex space into which air is introduced from a pressurized source. A low pressure region thereby produced in the vortex space draws the paper sheet toward the guide plate. At the same time, circulating air spirals outwardly from the vortex space to form a thin air film or air bearing between the sheet and the paper guide.