OPTICAL RECORDING AND REPRODUCING DEVICE

摘要

PURPOSE:To attain stable servo application by driving an objective lens by a focus error signal and a tracking error signal outputted through the detection of the objective lens and a recording medium and by a focus displacement signal and a tracking displacement signal outputted through the detection of the displacement from a still position. CONSTITUTION:A light from a light source 1 passes through a collimator lens 2 and a half mirror 3, is stopped into a minute spot by the objective lens 4 and irradiated onto the recording medium 5. The light reflected on the recording medium 5 is reflected on the half mirror 3 through the objective lens 4 and made incident on a photodetector 7 through a convex lens 6. A focus direction objective lens drive element 10 is driven by an output of a focus direction objective lens drive circuit 9 which inputs a displacement signal output from a focus direction objective lens position detector 14 detecting the displacement of the objective lens 4 from the focus direction still position and inputs a signal between an output signal of a phase compensation circuit 16 and a focus error signal from the photodetector 7 so as to constitute a servo system keeping the distance between the objective lens 4 and the recording medium 5 to a constant value. This is applied to the tracking control similarly.