Apparatus for sensing sheets
US5007628A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 26, 1989 |
| Grant date | Apr 16, 1991 |
| Priority date | — |
| Expiry date | May 26, 2009 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB65H2701/1912
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Apparatus for sensing the passage of sheets (1) through a nip formed by rollers (5 and 6), includes a core (14), moving with the shaft of one of the rollers, and a flat coil (15) connected to an oscillator circuit for sensing the deflection of one roller relative to the other. The oscillator circuit (18) provides a train of signals the frequency of which varies with the amount of the relative deflection of the rollers, and a counter (19) counts the signals from the oscillator in a fixed time interval. A store (22) stores counts representing the relative deflections of the rollers in a cycle of movement of the rollers when no sheet is present. The difference between a subsequent count and a stored count for a corresponding position in the cycle of rotation of the rollers is compared with a predetermined threshold, to establish the presence or absence of a sheet between the rollers.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.