PURPOSE: To know whether a form is peeled off at an adequate position, by arranging a density read sensor behind a position where the form wound around a drum in normal copying operation is peeled, and utilizing its output.
CONSTITUTION: An exposure attenuating plate 2 is inserted temporarily through a solenoid into the optical path extending from an exposure lamp 1 to a drum 8, and trial density on the drum 8 is read by a read sensor 11 to adjust the amount of toner to be supplied. This read sensor 11 is arranged behind the position A where the form is peeled off and its output is divided into two; one is led to an operational amplifier 16, which compares the input with a reference voltage to know whether the output of the sensor 11 is a reflected output from the drum 8 or that from a form surface, thus detecting a form wound erroneously.
YASUI HIROKAZU
MATSUURA AKIRA
HIRAYAMA YOSHIFUMI
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