Device for calibrating an apparatus for measuring the formation index of a sheet of paper
US4931659A · kind A · utility
5Cited by
4References
7Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | May 20, 1988 |
| Grant date | Jun 5, 1990 |
| Priority date | — |
| Expiry date | May 20, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/274
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A device for calibrating an apparatus for measuring the formation index of a sheet of paper in which an emitted light beam is directed through the sheet of paper and detected and electronically processed into a modulated output signal. The device has a frosted glass for diffusing the measuring beam of light and an opaque rod mounted for rotation in and out of the beam of light so as to provide a modulation of the detected light of a known amount which can then be used to calibrate the measuring apparatus by adjusting the various parameters of the apparatus to yield the desired known output modulation.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.