Apparatus and method of measuring web feeding velocity by using single field encoder
US9784756B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | May 9, 2014 |
| Grant date | Oct 10, 2017 |
| Priority date | — |
| Expiry date | May 7, 2036 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01P3/54
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A method of measuring feeding velocity of a web, on which a scale having pitches different from pitches of a mask are formed, is provided. The method includes: calculating a number of vibrations of a moiré image of light passing through the mask and the scale; calculating pitches of the scale of the fed web based on the calculated number of vibrations of the moiré image; averaging the pitches of the scale so that a change in a pitch between adjacent timings among the calculated pitches of the scale is minimized; extracting first signals corresponding to our phases for one pitch based on the averaged pitches of the scale; calculating two second signals for forming a Lissajous circle from the first signals; and calculating an angle of the Lissajous circle by the two second signals and then calculating the feeding velocity of the web by using the calculated angle.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.