Method and apparatus for sensing sheets
US4700368A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 18, 1985 |
| Grant date | Oct 13, 1987 |
| Priority date | — |
| Expiry date | Dec 18, 2005 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB41J29/44
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Apparatus for sensing the passage of sheets (1) through a nip formed by rollers (5 and 6), includes means for sensing the deflection of one roller relative to the other, the sensing means including an oscillator (18) providing a train of signals the frequency of which varies with the amount of the relative deflection of the rollers, and a counter (19) counting the signals from the oscillator in a fixed time interval. Means (23) are provided for storing counts representing the relative deflections of the rollers in a cycle of movement of the rollers when no sheet is present, and for comparing the difference between a subsequent count and a stored count for a corresponding position in the cycle of rotation of the rollers, with a predetermined threshold, to establish the presence or absence of a sheet between the guide members. The sensing means may comprise a core (14), moving with the shaft of one of the rollers, and a solenoid (15) connected to the oscillator circuit.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.