Objective lens driving device with multipole magnet

An objective lens driving device with a multipole magnet, which comprises:

• a yoke having a disk-shaped base section, a central yoke section with a central hole, and at least three flat yoke sections;
• a supporting shaft set upright in said central hole of said central yoke section;
• a lens holder with a central aperture fitted over said supporting shaft for rotary movement about and vertical movement along said supporting shaft and having a cylindrical coil mount extending downwardly therefrom;
• a ring-shaped focusing coil mounted around said cylindrical coil mount for moving said lens holder along said supporting shaft for effecting focusing;
• at least one rectangular tracking coil attached to a side of said focusing coil such that a pair of vertical coil sides of said tracking coil are parallel to said supporting shaft;
• and
• curved multipole magnet means sandwiched between said disk-shaped yoke section and said three flat yoke sections and having at least three magnet sections, with opposite end magnet sections having a polarity opposite to that of a central magnet section so that said vertical coil sides interlink with magnetic fluxes having substantially opposite directions to each other whereby forces act upon said vertical coil sides in substantially same direction.

An objective lens driving device with a multipole magnet, which comprises:

• a yoke having a disk-shaped base section, an inner central yoke section with a central hole therein, and an outer cylindrical yoke section;
• a supporting shaft set upright in said central hole of said inner central yoke section;
• a lens holder with a central aperture fitted over said supporting shaft for rotary movement about and vertical movement along said supporting shaft and having a cylindrical coil mount extending downwardly therefrom;
• a ring-shaped focusing coil mounted on said cylindrical coil mount for moving said lens holder along said supporting shaft for effecting focusing;
• curved multipole magnet means disposed between said inner and outer yoke sections;
• at least one rectangular tracking coil attached to a side of said lens holder such that a pair of vertical coil sides of said tracking coil are parallel to said supporting shaft;
• and
• tracking multipole magnet means disposed in the vicinity of said tracking coil and having at least two magnet sections having a polarity opposite to that of an adjacent magnet section so that said vertical coil sides interlink with magnetic fluxes having substantially opposite directions to each other whereby forces act upon said vertical coil sides in substantially same direction.