Optics: measuring and testing – By dispersed light spectroscopy – Utilizing a spectrometer
Patent
1995-06-12
1997-06-24
Evans, F. L.
Optics: measuring and testing
By dispersed light spectroscopy
Utilizing a spectrometer
356429, 356 72, G01J 342, G01N 2186
Patent
active
056421923
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.
REFERENCES:
patent: 4499821 (1985-02-01), Lee
patent: 4659193 (1987-04-01), Nagano
patent: 5047652 (1991-09-01), Lisnyansky et al.
PCT Search Report, Int. App. No. PCT/US96/09736, Dated Oct. 9, 1996.
Alguard Mark J.
Gordon Daniel A.
Evans F. L.
Measurex Corporation
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