System for measuring the relaxed length of a moving web
US4984458A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 13, 1990 |
| Grant date | Jan 15, 1991 |
| Priority date | — |
| Expiry date | Jun 13, 2010 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB65H2301/4148
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method and apparatus for measuring the relaxed length of a moving web includes forming a plurality of detectable marks along the length of the web at a repeated length interval. First and second detectors positioned along the web path are separated by a known distance S. A first tensioning force is applied to the moving web, and a first tensioned repeat length of the web is measured by detecting a mark moving past the first detector and then detecting the next mark moving past the second detector. The time separating the detections is determined. A second tensioning force of a known proportional relationship with the first tensioning force is applied to the moving web. A second tensioned repeat length is measured. The speed of the moving web is measured, and a relaxed length is calculated from the first tensioned repeat length, the second tensioned repeat length, and the proportional relationship between the first and second tensioning forces.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.