Drive apparatus for objective lens

A drive apparatus comprising:

• first and second objective lenses having different optical characteristics respectively for focusing a light beam on an optical recording medium, each lens having an optical axis;
• a lens holder having an axis of rotation and supporting the first and second objective lenses, said lens holder capable of moving in a direction of one of the lens optical axes and turning about the axis of rotation;
• an optical system defining an optical path along which a light beam is transmitted to a selected one of the first and second objective lens;
• means for generating a tracking signal and a focusing signal;
• means for generating a switching signal;
• driving means comprising first magnets and first coils facing the first magnets respectively, for turning the lens holder about the axis of rotation in response to the tracking signal in a first selection mode in which the objective lens is located in the optical path;
• said driving means further comprising second magnets and second coils facing the second magnets respectively, for moving the lens holder along one of the lens optical axes in response to the focusing signal in the first selection mode,
• wherein when the first magnets and first coils energized by the switching signal rotate the lens holder to change from the first selection mode to a second selection mode in which the second objective lens is located in the optical path, the first coils face the second magnets, respectively, and the second coils face the first magnets respectively, the first magnets and the second coils turn the lens holder about the axis in response to the tracking signal in the second selection mode, and the second magnets and the first coils move the lens holder along one of the lens optical axes in response to the focusing signal in the second selection mode;
• and
• means for generating an initializing signal to energize the second coils so that the lens holder is rotated in the second selection mode to chance from the second selection mode to the first selection mode, and the lens holder is moved along one of the lens optical axes in the first selection mode to maintain the first selection mode.

A driving apparatus comprising:

• for holding first and second optical systems having different numerical apertures, respectively;
• means for rotating said holding means around a rotational axis;
• means for generating an initializing signal to initialize the driving apparatus;
• and
• means for energizing said rotating means in response to the initializing signal to locate the first optical system in a predetermined position,
• wherein said rotating means comprises:
• first driving means having first magnets and first coils for turning said holding means about the rotational axis in a first mode in which the first optical system is selected;
• and
• second driving means having second magnets and second coils for moving said holding means along the rotational axis in the first mode in which the first optical system is selected;
• wherein:
• the first magnets and the second coils act in a combination to form a third driving means for turning said holding means about the rotational axis in a second mode in which the second optical system is selected;
• the second magnets and the first coils act in a combination to form a fourth driving means for moving said holding means along the rotational axis in the second mode in which the second optical system is selected;
• and
• the second coils supplied with the initializing signal causes said holding means to either maintain the first mode or change from the second mode to the first mode.

A driving apparatus comprising:

• rotary structure having a rotation center;
• means for allowing said rotary structure to be rotated between first and second positions around the rotating axis and to be shifted along the rotating axis;
• driving means including first and second magnets and first and second coils, the first magnet and first coil constituting a first electromagnet driving means for rotating the rotary structure and the second magnet and second coil constituting a second electromagnet driving means for shifting the rotary structure, when the first potion is selected, and the first magnet and second coil constituting a third electromagnet driving means for rotating the rotary structure and the second magnet and first coil constituting a fourth electromagnet driving means for shifting the rotary structure, when the second potion is selected;
• first generating means, selectively connected to one of the first and second coils, for generating a first driving signal to energize the selected one of the first and second coils to rotate the rotary structure;
• second generating means, selectively connected to the other one of the first and second coils, for generating a second driving signal to energize the selected the other one of the first and second coils to shift the rotary structure;
• and
• connecting means for connecting the first generating means to the first coil and the second generating means to the second coil when the first position is selected, and connecting the second generating means to the first coil and the second generating means to the first coil when the second position is selected.