| 摘要 |
PURPOSE:To ensure the automatic switching of a bias equalizer, by forming the opaque stripes of a number in accordance with the types of tape at the leader tape part and counting the number of stripes while a tape is travelling. CONSTITUTION:A light emitting diode 4 glows by the light emitting diode driving signal Q1 in the recording/reproducing mode, and the output of a phototransistor 5 is turned into the pulse signals proportional to stripes (k) and (l). An AND circuit 7 is opened only for these pulses, and the clock signals are counted by a counter circuit 9. When the number of clocks equivalent to the reference signal (k) is counted by the counter circuit, a pulse Q3 resets a counter 9 which counts the number of signals (l) to discriminate the type of the tape. Then a 1-shot circuit 10 is triggered to obtain a signal Q4. This signal Q4 opens an AND gate 11 and counts pulses Q5 existing between two reference signals (k) through the counter 9. According to the number of pulses Q5, a bias equalizer is switched. |
