| 摘要 |
PURPOSE:To reduce the number of parts and improve the performance of a disk player, by making an automatic punching circuit which automatically punches the data of reproducing signals necessary when a disk is reproduced and a track counting circuit which counts the number of tracks of a disk in one body and commonly usable CONSTITUTION:An RF signal A from a disk is converted into an AC signal by a capacitor C1 and then converted into a digital signal D by a multistage amplifier 1. The digital signal D is inputted into a comparator 2 which constitutes a negative feedback circuit for punching the RF signal A at an appropriate level together with a subtractor 3. A signal B is a change-over control signal for using the comparator 2 as a comparator for automatically punching the RF signal A at the time of normal reproduction of a disk and as a comparator for track detection when a disk is subjected to accessing, trick play, etc. That is to say, by means of control signals B1 and B2 a switch SW1 is turned on and another switch SW2 is turned off at the time of normal reproduction and the switch SW1 is turned off and the other switch SW2 is turned off at the time of track counting. |
