Valmet IQ Web Color Measurement
Online full-spectrum color analysis by Valmet IQ Web Color Measurement (IQ Web Color) provides a solid foundation for Valmet’s unique, multi-variable, machine-direction color control.
IQ Web Color is a factory pre-calibrated spectrophotometer for a variety of paper and board grades in which visual uniformity is important. These include newsprint, printing papers, fine papers, covers and packaging materials. With its full-spectrum measurements, IQ Web Color detects the detailed effects of furnish, paper dyes and optical brightening agents.
IQ Web Color is an online, scanning spectrophotometer that measures sheet color, brightness, whiteness, and opacity. The sensor provides opacity compensated color measurements for both UV-included and UV-excluded color, and it is especially designed for accurate, stable readings in a papermaking environment.
In the detector head, the light source is a flashing, UV-rich Xenon lamp, followed by a filter wheel to provide the illumination for UV-included and UV-excluded color measurements. The flashed light is mixed and focused on the web. The light reflected from the sheet is detected by the 1st channel of the dual spectrophotometer. Simultaneously, the illumination spectrum is detected by the 2nd channel of the spectrophotometer. This reference is used to compensate the variations in Xenon flash and environmental effects.
On the opposite side of the web, there is a source head with a flashing LED light source integrated in the white backing. The white LED is used as an illumination of the transmission spectrum that is detected in detector head. Thus, single sheet color measurements are corrected to infinite backing values using an advanced proprietary algorithm.
The simple, compact design of the dual spectrophotometer ensures that optical alignment and measurement stability are maintained. The measurement follows a 45/0° optical geometry. With illumination from all directions color and brightness measurements are independent of sheet surface properties such as fiber orientation. The unique illumination and detection optics design assures the passline insensitivity of the measurement. The detector head contains a white tile, used in sensor standardization as calibration verification standard. An integrated sheet stabilization device is used to eliminate sheet flutter for stable online readings.
- Accurate and stable full-spectrum measurements for precise control of sheet color uniformity using multiple dyes and optical brightening agents.
- Full-spectrum opacity compensation through transmittance spectrum measurement for minimized grade-dependency.
- Superior speed; opacity compensated scan averages and color profiles for both UV-included and UV-excluded color after each scan.
- Faster on-spec quality and reduced startup waste.
- Compact design.
- Excellent correlation to offline laboratory tests including Valmet Paper Lab. Automatic calibration verification link is also available.