Ppg Industries, Inc.

Forrest W Decker

Hobart E Kenton

Jacob R Peternel

Reflected energy density signal as a function of distance in pulse counts determined from a side of stacked sheets is used to calculate sheet pulse counts. A working pulse range is determined from the nominal thickness range of the stacked sheets and thereafter pulse values within the working pulse range are selected. The calculated sheet pulse counts and selected pulse values are compared and acted on to develop a pair of sheet counts for each selected pulse value. The pair of sheet counts occurring at least 10 consecutive times is considered the number of sheets in the stack.

Method of and apparatus for determining number of sheets in a stack

A carriage having (1) an infrared energy ray emitter and detector and (2) an encoder is displaced over a side of stacked glass sheets to sense density of reflected energy rays as a function of carriage position on the stack. The sensed density of reflected infrared energy rays from the edges of the outermost sheets and the interface between adjacent sheets is less than the sensed density of the reflected rays from the sides of the sheets. The output signal of the encoder and of the detector is acted on to determine the number of sheets in the stack.

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Pittsburgh, PA, United States of America

Forrest W Decker