| 摘要 |
PURPOSE:To reduce the noise level which is due to the leakage of PCM signals as in the case of a 3-spot optical pickup, by increasing the loop gain in an access mode to reset a prescribed gain in a normal reproduction mode and to realize a quick and accurate access and at the same time setting the loop gain at the minimume necessary level in the normal reproduction mode. CONSTITUTION:A switch control circuit 21 delivers a high control signal when it gives an access to a pickup 4 at a point A and connects a switch circuit 20 to the (b) side from the (a) side to increase the loop gain of a servo loop by an amount equal to the gain of an amplifier 22. The circuit 21 is set at a low level at a point B when an access is over and connects the circuit 20 to the (a) side. Then a reproduction is carried out when the loop gain is reduced. |
