| 摘要 |
PURPOSE:To attain stable reproduction by applying peak hold to a focus error signal, AD-converting the result, multiplying it with the original focus error signal after a prescribed operating processing so as to set automatically a focus servo gain to a proper value in response to a disc to be reproduced. CONSTITUTION:A focus error signal FE obtained via a pickup 21 and an operation circuit 22 is converted into a binary data of a peak value X by a peak hold circuit 51 and an AD converter 52, a prescribed value Z is divided by an operation circuit 54 and the relation of Y=Z/X is obtained. An output of the circuit 54 is multiplied with the signal FE from the circuit 22 at a multiplier circuit 23 via a memory 55 and a D/A converter 56 and a prescribed value Z is obtained. On the other hand, a reproducing information signal RF of the circuit 22 is inputted to a focus detection circuit 33, a detection pulse B is outputted, a switch 24 is thrown to the position F via an AND gate 34 and an FF32, a focus servo loop is set, and the focus servo gain is set automatically to the proper value Z in response to a disc 10. |
