DETECTION AND DISPLAY DEVICE FOR TAPE REMAINING QUANTITY

摘要

PURPOSE:To detect the magnetic tape remaining time before a tape is driven by revolutions of both supply and take-up reels in the same direction, by detecting the number of revolution of the supply reel different by the number of turns of the tape to the supply reel in the automatic tape loading/unloading mode and then calculating the tape remaining time. CONSTITUTION:A disk 22 having a slit is attached coaxially to a rotary shaft 4 of a supply reel drive disk for a supply reel 2. An LED24 is provided above the disk 22, and a photointerrupter 23 consisting of a phototransistor 25 is provided under the disk 22 respectively. A mechanism part 32 is driven by the control output of a control part 30 which detected that a cassette housing 1 is loaded. The supply reel drive disk is revolved for a period from the start to the end of a tape loading action. The pulses obtained when the slit of the disk 22 revolving coaxially to the shaft 4 is detected by the interrupter 23 are fed to a counter 26. Thus the pulse number (n) is counted and supplied to an arithmetic part 28. Then the tape remaining time T is obtained as shown by an equation [ I ] from the pulse number (n) of the part 28.