| 摘要 |
<p>PURPOSE:To shorten the time required for tape end detection by obtaining a different pulse from a detection pulse for the rotation of a reel turntable and by achieving the tape end detection by using the obtained pulse. CONSTITUTION:The base circuit of a transistor (TR) Q4 turns on for a certain time when a Hall IC6 changes from an H to L, thereby charging a capacitor C5 through a resistance R9 and a diode D4. Since the capacitor C5 is charged when the output of the Hall IC6 changes from the L to H and H to L, the discharge time constant C5XR14 is reduced approximately to half as compared with the conventional one, and consequently the detection time for the ending terminal and starting terminal of a tape is nearly halved. The output of the Hall IC7 is inputted to a microcomputer M and stored in an RAM9 to set a zero flag ZF11 at need.</p> |
