BLATTSENSOR.

摘要

Apparatus for sensing the passage of sheets through a nip formed by rollers (5 and 6), includes a core (14), moving with the shaft (1) of one of the rollers (5), and a flat coil (15) connected to an oscillator circuit (18) for sensing the deflection of one roller (5) relative to the other (6). 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 (18) in a fixed time interval. A store (23) stores counts representing the relative deflections of the rollers (5, 6) in a cycle of movement of the rollers (5, 6) 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 (5, 6) is compared with a predetermined threshold (55), to establish the presence or absence of a sheet between the rollers (5, 6).