| 摘要 |
PURPOSE:To prevent the titled mechanism from malfunction due to steady light such as external light by inputting a tape end signal to a microcomputer synchronously with the peak position of a differential signal outputted from a tape end sensor. CONSTITUTION:A tape end LED control signal (a) is changed by the microcomputer 20 to emit a tape and detecting light emission diode (LED) 10. When the emitted light is detected by a phototransistor 7 at the end of a tape, a tape end sensor output (e) is outputted and differentiated by a capacitor 5 to obtain a tape end sensor output differential signal (b). A comparator 1 compares the differential output (b) with a reference voltage signal (c) and outputs a tape end signal (d), but the microcomputer 20 enters an end signal (d) when the outputted differential signal (b) reaches a saturated voltage, stores the result and immediately sets up a tape end LED control signal (e) to 'H'. Since one point of the end signal (d) is inputted in each period, the tape end information can be obtained during microcomputer processing if necessary by checking conversion TAPEND.
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