In today’s competitive printing market job size and time to production are continually getting shorter while customer expectations for highly accurate color reproduction and consistency even between multiple presses are increasing. Historically to ensure this quality of color accuracy measurements using timely hand held out of line spectrophotometers during the job run, between shifts or after job runs was the only way to try and ensure color accuracy. These traditional external spectrophotometers required annual calibration at ISO certified sites which were expensive and placed the device out of service for a considerable time. These devices were also increasingly subject to early obsolescence and the accuracy of the measurements dependent on the training and capabilities of the manual user.
Traditional Spectrophotometers
Traditional spectrophotometers measure specular reflectance by first illuminating the color target with white (polychromatic) light. The reflected light is then passed through a diffraction grating to measure reflected light intensity at various wavelengths. These measurements are then compared to measurements taken on a reference target (White and Black) and the set of relative values is then calculated as the measured spectra for the given target. The accuracy of the measurements is continuously affected by the frequency and intensity of the light source which changes significantly as the bulbs age.
Color Sentinel Modeling Photo Spectrophotometer
The family of in line Color Sentinel modeling spectrophotometers uses a revolutionary patented technology that eliminates the need to ever field calibrate the device enabling it to be installed in line with the paper path after the fuser output and before the finishing stations and make measurements at full production speeds.
In response to a printer color calibration request from the CMS or job control system the ILMS looks for a prepared set of color patches being printed at full production speed. The ILMS then illuminates these target patches with numerous highly stabilized nearly monochromatic LED light sources at specific frequencies. The patented optical system then measures the intensity of each light source at as it is reflected off the target as it passes under the ILMS. The internal sensor characterization process within the ILMS then calculates and maps the LED readings to the 31 spectral readings of any reference spectrophotometer. As a modeling spectrophotometer the output can be configured for M0, M1 or M2 modes or any custom configurable mode. This information is then sent to the CMS which evaluates the color coherency and utilizes its internal color (or as a result of internal IOT controls) to alter the color to keep the printed output consistent. This real time, closed loop operation completely eliminates the need to stop the press and evaluate the color quality.
Once characterized at the factory the devices can then perform real-time color measurements in the host device without requiring out of path calibration
Advantages
- In-Line Modeling Spectrophotometer assures perfect color every time
- Provides data for automatic toner/ink adjustment recommendations to correct for paper, ink, temperature and machine differences
- Enables precise color matching of CMYK and spot color via in path color measurements
- Real time press measurements at up to 120 meters per minute
- Simultaneous measurements of L*a*b, and 31 point spectral data
- Assures consistent color over time and between individual presses
- Perfect color output for more customer satisfaction & fewer reruns
- Less down time and waste equals more productivity!
Products
CSS 110 – Portable Handheld Reflection Spectrophotometer (download data sheet PDF)
ILS™ Inline Scanning Spectrophotometer (download data sheet PDF)
Powerscan™ – High-Speed X-Scanning Spectrophotometer (download data sheet PDF)
PRESS RELEASE – Color Sentinel System Debuts Self-Calibrating In-Line Spectrophotometers (PDF)