| 摘要 |
PROBLEM TO BE SOLVED: To provide a film position detector which can adjust the output voltage of a position detection sensor, with simple configuration. SOLUTION: The film position detector is provided with a film-feeding roller 2 for carrying a 35 mm film 1 having perforation 1a; a reflection sensor 4 constituted by an LED (light-emitting diode) 7 arranged along a film passage and a phototransistor 8; and a microcomputer 6, directly connected to a roller driving motor 3 and connected to the reflection sensor 4 via a comparator 5. In the LED 7 or the phototransistor 8 of the reflection sensor 4, the current flowing therethrough decreases with the lapse of time. In order to compensate for this, the threshold voltage outputted from the microcomputer 6 is adjusted, and the timing of the rise and fall edges of the output voltage of the comparator 5 is controlled so as to be always a constant. COPYRIGHT: (C)2005,JPO&NCIPI
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