초록 ▼

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 r

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.

대표청구항 ▼

Apparatus for sensing the passage of sheets through a nip, said apparatus comprising: a pair of guide members whose surfaces define said nip, said guide members being moveable in a cyclic manner to advance said sheets through said nip and being displaceable with respect to one another as a function

Apparatus for sensing the passage of sheets through a nip, said apparatus comprising: a pair of guide members whose surfaces define said nip, said guide members being moveable in a cyclic manner to advance said sheets through said nip and being displaceable with respect to one another as a function of the thickness of one or more sheets passing through said nip; sensing means for sensing a deflection of said guide members relative to one another and for generating a train of signals whose frequency varies as a function of the amount of relative deflection of said guide members; counter means for generating n present count values for each cycle of movement of said guide members, n being a integer greater than 1, each present count value being representative of the number of signals generated by said sensing means during a respective sampling interval corresponding to a respective portion of said surface of said guide members; storing means for storing n no-sheet count values for a single cycle of movement of said guide members, each no-sheet count value representing the relative deflection of said guide members with respect to one another when no sheet is present between said nip for a respective one of said portions of said surface of said guide members so that each of said no-sheet count values corresponds to a respective one of said present count values; comparing means for comparing, for each cycle of movement of said guide members, each present count value with its corresponding no-sheet count value and for generating a respective difference signal for each said comparison; and determining means for obtaining an average of said difference signals for each said cycle of movement of said guide means and for comparing said average with a predetermined threshold value to determine the presence or absence of a sheet in said nip.