| 摘要 |
PURPOSE:To prevent a signal from being recorded on other track in error by providing an out-of-focus detection circuit detecting the disorder of focus and a beam output control means controlling an optical beam output with the output of the out-of-focus detection circuit. CONSTITUTION:An error amplifier circuit 38, a focus control circuit 41, a drive circuit 42 and a drive coil 43 constitute a loop of the focus control system. When a tracking-off detection circuit 31 and the out-of-focus detection circuit 39 detects an off-track or an out-of-focus, the output of the circuits goes to 'H' and the outputs are inputted to a OT circuit 40. Thus, either the tracking- off detection circuit 31 or the out-of-focus detection circuit 39 detects a tracking- off or an out-of-focus, the output of the OR circuit goes to 'H', the signal is inputted to a control signal generating circuit 32, from which a control signal disabling laser recording is generated. |
