Dual spectrometer color sensor
US5793486A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 21, 1996 |
| Grant date | Aug 11, 1998 |
| Priority date | — |
| Expiry date | Nov 21, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/86
- WIPO fieldMeasurement
- WIPO sectorInstruments
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. Light beams from the two sources are combined to form a sheet-illuminating third beam approximating the D65 standard source. The intensity of the flashlamp is electronically controlled to maintain the balance of UV to visible light that characterizes the standard source. The color sensor further includes a sheet backing system including a rotatable st…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.