Methods and apparatus for measuring characteristics of moving webs
US5233195A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 25, 1992 |
| Grant date | Aug 3, 1993 |
| Priority date | — |
| Expiry date | Feb 25, 2012 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N23/083
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Characteristics of moving webs are measured using a radiation source shutter which is rotatably movable between an opened-shutter position and a closed-shutter position and structured to permit access to the radiation source in the closed-shutter position. The source is configured to produce a fan-shaped radiation beam which passes through the web to a detector. The sizing of the fan-shaped beam and the detector together with the spacing the source and the detector are such that the beam width is substantially less than the detector while its length is greater than the detector. This novel beam shaping, detector arrangement provides composition insensitivity, increases solid beam angle and superior streak detection by aligning the beam length dimension with the direction of web movement. Alignment insensitivity is obtained by tuning the radiation beam using concentric rings or crossed strips of material which is semi-transparent to the radiation to compensate for geometric characteristics of the radiation source/beam and the detector. Air within an open portion of a measuring column extending between the radiation source and detector is conditioned and also used to condition electr…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.