| 摘要 |
PURPOSE:To shift a pickup to the objective position quickly with less number of times of reading, by converging the shifting distance of the pickup to an objective position by reducing the distance half by half sequentially including both forward and reverse direction. CONSTITUTION:A data at the center of a recording band is set to a register 10 by giving a start command pulse. The head is shifted with the command of the register and when the data of the register is the same as that as shown by a counter 8 in the fig. (c), an output of a differential comparison circuit 9 is fed to a coincident pulse generating circuit 13, an address on a disc is read from a terminal T1 with the output and the address is apllied to a reproducing address register 16. A comparator 18 adds a signal to a gate 20 when the reproducing address is larger than a command address. An input of a shift register 15 goes to 1 with the command address (a) and the other goes to 0, further, an output of a delay circuit 14 makes shift. The output of the next stage and succeeding is inputted as reading clock to the register 10. The pickup is brought close to the objective address by repeating the operation. |
