| 摘要 |
PURPOSE:To detect intermusic accurately without being influenced by disturbing light by cutting off signals lower in frequency than low band cut off frequency and signals higher in frequency than high band cut off frequency during searching, and detecting the level of signals including DC component during tracing. CONSTITUTION:Output of a sensor 1 is DC amplified by a pre-DC amplifier 4 and supplied to a band passing device 11. At the time of searching, frequency of a music interval signal is included between low band cut off frequency f1 and high band cut off frequency f2, accordingly, the signal is transmitted to a comparator 6. However, as frequency of signals in music area is out of the range of low band cut off frequency f1 and high band cut off frequency f2, the signal is cut off and not inputted to the comparator 6. Accordingly, only the intermusic signal is compared with reference potential V1 and the intermusic is detected accurately. On the other hand, when a pickup is tracking a disk record, the output of the pre-DC amplifier 4 is further amplified by a DC amplifier 5, inputted to a comparator 8, compared with reference potential V2 and the intermusic detected. |
