| 摘要 |
In a tracking or focusing servo control loop (3b, 3c, 41, 20; 3a, 42, 21), there are provided a switch element (6a; 6c) for switch-controlling a tracking or focusing error signal, and a smoothing circuit (7a; 7c) for switching passage the error signal. An amount of detected reflection from an optical recording medium (11) is monitored by a controller section (3b, 3c, 5a, 6b, 7b, 8a; 3a, 5b, 6d, 7d, 8b), and the switching action of the switch element is ON/OFF-controlled by the controller section so as to maintain a servo loop gain at a predetermined standard. Thus, it is possible to maintain a constant servo loop gain without being influenced by variation in the laser light amount or difference in reflectivity characteristics of the recording layers of individual optical recording media, and constantly stable tracking servo control and/or focusing servo control can be performed. <IMAGE> |
