US Patent 7193937 Objective lens driving device and optical disk apparatus

Tracking coils are attached to outer surfaces of two focusing coils. Inside the focusing coils, a first magnet and a second magnet are arranged respectively. A third magnet is arranged so as to face the first magnet and the second magnet via the tracking coils. An open end of a first yoke for holding the first magnet and an open end of a second yoke for holding the second magnet are connected by a bridging yoke. Since a magnetic flux is formed in the bridging yoke, pitching vibrations can be suppressed and a driving sensitivity improves owing to an increase in an effective magnetic flux.