Agfa Gevaert Nv

Emiel Michiels

Jan Claes

Marc J Scheerders

The area of moving rectangular sheet material, such as exposed photographic material needing photographic development, is calculated by advancing the sheet material at a known speed along a straight path with one axis, e.g. the length, of the material aligned with the path pass dual sensors. The first sensor determines the length of the sheet material, e.g. by measuring the time interval for the leading and trailing edges of the material to pass the sensor, from which in conjunction with the known speed of advance, the length can be calculated. The second sensor is elongated and extends angularly across the path of advance at a fixed bias angle .alpha. and measures the time interval for the leading and trailing corners (relative to the angular orientation of the second sensor) to pass the second sensor, from which the distance separating such corners along the path can be calculated. From the difference between the latter distance and the length and the bias angle, the width of the sheet material can be calculated by a basic trigonometric function and the area is the multiple of the length and width. Preferably, the second sensor is sufficiently long to accommodate different sizes of sheet material.

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Antwerp, Belgium

Emiel Michiels