Viscoelastic substance and objective lens driving apparatus with the same

An objective lens driving apparatus comprising:

• an objective lens through which a light beam is applied to a predetermined position on an optical disk;
• a movable member for holding the objective lens;
• means for driving the objective lens in a predetermined direction with respect to the optical disk, the means for driving having a coil and a magnetic field forming means for applying a magnetic field to the coil, and the movable member being attached to one of the coil and the magnetic field forming means;
• and
• a magnetized viscoelastic substance having magnetic particles dispersed therein and arranged between the movable member and a fixed portion, for absorbing vibration of the movable member wherein magnetic attractions between the magnetic particles generating a force for restoring deformation of the viscoelastic substance when an external force acts on the viscoelastic substance.

An objective lens driving apparatus comprising:

• a base;
• an objective lens through which a light beam is applied to an optical recording medium;
• a movable member for holding the objective lens;
• supporting means for supporting the movable member to be movable along an optical axis of the objective lens with respect to the base;
• means for driving the movable member along the optical axis of the objective lens, the means for driving including magnetic field forming means for applying a magnetic field, and coil means situated in the magnetic field, for cooperating with the magnetic field, the coil means having a first coil wound around an axis parallel to the optical axis of the objective lens, the movable member being attached to one of the magnetic field forming means and coil means;
• and
• vibration absorbing means arranged between the coil means and the magnetic field forming means, for absorbing vibration of the movable member, said absorbing means including a viscoelastic substance having magnetic particles dispersed therein.

A magnetic driving apparatus comprising:

• a fixed portion;
• a movable portion, movable relative to the fixed portion;
• magnetic field forming means for applying a magnetic field to the movable portion;
• and
• vibration absorbing means arranged between the movable portion and the fixed portion, in the magnetic field, for absorbing vibration of the movable portion, said absorbing means including a viscoelastic substance having magnetic particles dispersed therein wherein magnetic attractions between the magnetic particles generating a force for restoring deformation of the viscoelastic substance when an external force acts on the viscoelastic substance.

An objective lens driving apparatus comprising:

• an objective lens through which a light beam is applied to a predetermined position on an optical disk;
• a movable member for holding the objective lens;
• means for driving the objective lens in a predetermined direction with respect to the optical disk, the driving means having a coil and a magnetic field forming means for applying a magnetic field to the coil, and the movable member being attached to one of the coil and the magnetic field forming means;
• and
• a viscoelastic substance having magnetic particles dispersed therein and arranged between the coil and the magnetic field forming means, for absorbing vibration of the movable member wherein magnetic attractions between the magnetic particles generating a force for restoring deformation of the viscoelastic substance when an external force acts on the viscoelastic substance.