Document handling and counting apparatus

A method for counting sheets employing apparatus including input and output locations and means for feeding sheets from said input location to said output location along a feed path arranged therebetween, first and second sensors spaced a predetermined distance apart along an imaginary line substantially perpendicular to said feed path, said method comprising the steps of:

• initiating a count of pulses representing movement of said sheets as soon as the leading edge of a sheet passes at least one of said sensors;
• determining which of said sensors the leading edge of the sheet passes first;
• saving the count being generated at the time that the leading edge of said sheet passes one of said sensors as a first count;
• terminating said count when the trailing edge of the sheet has passed one of said sensors;
• subtracting the saved value from said terminated count to obtain a difference value;
• converting said first count to a skew value in accordance with a predetermined conversion factor representing the angle between leading edge of the sheet and said imaginary line;
• multiplying said angle data and said first count to obtain the real length;
• comparing the real length of the present document with the real length of the previously examined document;
• halting the sheet feeding assembly and displaying an error if the difference between the real length of the compared sheet is greater than a predetermined value.

Apparatus for detecting the presence of doubles comprising:

• input and output locations;
• means for feeding sheets from said input location to said output location in a one-at-a-time fashion at spaced intervals and with gaps between the trailing and leading edges of adjacent sheets;
• a light source and cooperating sensing means for generating an output signal representing the presence of a gap and the presence and density of a sheet;
• means responsive to the change in said sensing means output signal when the leading edge of a sheet passes said sensing means for accumulating said output signal;
• first and second storage means;
• means responsive to the change in said sensing means output signal when the trailing edge of a sheet passes said sensing means for transferring the accumulated value to said first storage means;
• said last mentioned means further including means for generating a compare enable signal of a predetermined interval;
• means for transferring the contents of said first storage means to said second storage means upon termination of said compare enable signal;
• means for clearing the contents of said first memory storage means upon transfer of the contents of said first storage means and said second storage means.

A method for operating sensing means for sensing the changes in transmissivity of sheets detected by a pair of spaced apart sensors, the said changes being caused by the sheets moving in single file and passing said sensors including the steps of:

• storing the present transmissivity values developed by the sensors in the absence of a sheet;
• generating count pulses at a rate representative of sheet velocity;
• accumulating the count pulses when at least one of the sensor outputs differs from the previously stored transmissivity value associated therewith;
• storing a first accumulated count present when the other one of said sensors detects a change in transmissivity;
• storing a second accumulated count present when said one of said sensors detects the trailing edge of the sheet;
• storing a third accumulated count present when said other one of said sensors detects the trailing edge of the sheet;
• obtaining the difference count between the third and first counts;
• and generating an alarm condition if the absolute value of the difference between the difference count and the second count is greater than a first predetermined value.

A method for determining the presence of double fed sheets in apparatus having means for feeding sheets one at a time in spaced relationship along a feed path from an input location to an output location and first and second sensors spaced along an imaginary line perpendicular to said feed path for detecting radiation directed through said sheets from associated radiation sources comprising the steps of:

• (a) storing a first signal representing the sum of the output signals of both of said sensors in a first storage device in response to the movement of the leading edge of a first sheet past said sensors;
• (b) transferring said first signal to a second storage device;
• (c) clearing said first storage device;
• (d) storing a second signal representing the sum of the outputs of both of said sensors in said first storage device in response to the movement of the leading edge of a second sheet past said sensors;
• (e) comparing said first and second signals;
• (f) generating a doubles indication when the difference between the first and second signals exceeds a predetermined amount;
• (g) transferring said second signal to said second storage device upon completion of said comparison step;
• and
• (h) clearing said first storage location.

Apparatus for determining the presence of double fed sheets including in combination:

• means for feeding sheets one at a time in spaced relationship along a feed path from an input location to an output location,
• first and second radiation sensors spaced along an imaginary line perpendicular to said feeth path,
• respective radiation sources associated with said sensors for directing radiation through said sheets to said sensors,
• means for summing the output signals of said detectors,
• means including a first storage device responsive to movement of the leading edge of a first sheet past said sensors for storing a first summed signal,
• a second storage device,
• means for transferring said first signal to said second storage device,
• means for clearing said first storage device,
• said means including said first storage device responsive to movement of the leading edge of a second sheet past said sensors for storing a second summed signal,
• means for comparing said first and second summed signals and means responsive to said comparing means for generating a doubles indication when the difference between the first and second signals exceeds a predetermined amount.