| 摘要 |
PURPOSE:To eliminate the need for a pulse generating circuit and a sampling/ holding circuit to simplify the circuit constitution by obtaining a tracking error detecting signal from a signal synthesizing part which synthesizes the sampling outputs obtained from the 1st and 2nd signal sampling parts. CONSTITUTION:A sampling output signal S11 of a signal S1 is obtained from a switch 21 in a period during which a rectangular wave signal S9 is set at a low level. While a sampling output signal S12 of the signal S1 is obtained from a switch 22 in a period during which a rectangular wave signal S10 is set at a low level. At a subtractor circuit 23, the signal S12 is subtracted from the signal S11 to obtain a difference signal S13. This signal S13 is supplied to an LPF24 to obtain a signal S14 having a change of amplitude corresponding to the peak value change of the signal S13 at its output end and also having the polarity corresponding to the polarity of the signal S13. Such a signal S14 is equal to a detection signal to the shift of the incident position of the laser light to the information recording truck. Then a tracking error detecting signal is obtained. |
