JPS56145577A - Detecting device for tape residual quantity - Google Patents

Abstract

PURPOSE:To grasp accurately that the tape residual quantity has reached a prescribed quantity, by providing N pieces of detectors, a rotation detector to output pulses, and a frequency divider to output rotation period signals on concentric circles of the tape reel table. CONSTITUTION:Four detecting parts 4 consisting of holes are provided through tape reel table 1 at equal intervals on the same circle of table 1, and light emitting element 5 and light receiving element 6 are arranged oppositely to each other in both sides of table 1 to constitute rotation detector 7 which detects rotating detecting parts 4 by elements 5 and 6 to output pulses. Amplifier 8 and waveform shaping circuit 9 are connected in series to light receiving element 6, and pulse generating circuit 10 which outputs clock pulses which become the reference for period measurement, the first frequency dividing circuit 11 which divides the pulse train signal output from waveform shaping circuit 9 by factor 4, and the second frequency dividing circuit 15 which has the trigger terminal connected to the output terminal of the first AND gate 14 are provided. As a result, it is grasped accurately that the tape residual quantity has reached a prescribed quantity with a simple constitution.