| 摘要 |
PROBLEM TO BE SOLVED: To make possible surely focusing a focal point required by a user on an information track when a bifocal lens is used. SOLUTION: This device is constituted so that when forced focus control is performed through a focus search signal generator 85 and a selector 81, though a focus error signal shows a focus lock state, and a selector control part 82 detects this matter, a malfunction preventive signal generator 84 and an error prevention circuit 83 make so that the selector 81 doesn't respond to its focus lock detection signal, and only when a condition that the required focal point is locked first always is ready, the malfunction prevention circuit 83 supplies the detection signal of the selector control part 82 to the selector 81. |
