| 摘要 |
PURPOSE:To quickly perform switching between the focus leading-in operation and the focus control operation by providing a focus servo switch circuit which performs this switching. CONSTITUTION:A focus servo switch circuit 28 is provided, and a focus leading-in instruction and a focus releasing-in inhibition signal of a microcomputer 10, the output of a focus zero cross detector 9, the output of a detector 8 which detects the start time of the leading-in operation, and the output of a detector 12 which detects the operating direction of a focus actuator 2 are inputted to this circuit 28 as input signals, and a switch input signal by which an amplifier which drives the actuator 2 performs the focus leading-in operation and the focus control operation is outputted from the circuit 28 as an output signal. When it is detected by outputs of detectors 8 and 9 that a focus error signal 14 indicates the in-focus state, the circuit 28 stops the focus search operation performed till then and operates a switch 11 and controls the actuator 2 so that the laser light from a laser diode 1 is focused on a medium 3. |
