Electromagnetic actuator with auto-retaining of rotor at triple positions

A shutter apparatus comprising:

• a shutter blade that is arranged on a substrate having an aperture and that opens and closes the aperture;
• and an electromagnetic actuator that is engaged with the shutter blade and that drives the shutter blade to open and close the aperture, wherein
• the electromagnetic actuator comprises a rotor that is composed of a permanent magnet and that is rotatable in two directions between a first end position and a second end position via an intermediate position, a coil that is wound around the rotor and that rotates the rotor in an energizing state where an electric current is applied to the coil, and auto-retaining means for retaining the rotor at one of three positions selected from the intermediate position, the first end position and the second end position under a non-energizing state where the electric current is not applied to the coil, the auto-retaining means comprising an elastic member that regulates the rotor at the intermediate position by a mechanical elastic force, a first magnetic member that is opposed to the permanent magnet and that retains the rotor at the first end position by a magnetic attractive force, and a second magnetic member that is opposed to the permanent magnet and that retains the rotor at the second end position by a magnetic attractive force, and wherein
• the shutter blade is driven to one of three positions selected from a full opening position for opening the aperture, a full closing position for closing the aperture, and a half opening position for partially opening the aperture, the three positions of the shutter blade corresponding to the three positions of the rotor.

A diaphragm apparatus comprising:

• a diaphragm blade that is arranged on a substrate having an aperture and that regulates a diameter of the aperture;
• and an electromagnetic actuator that is engaged with the diaphragm blade to drive the diaphragm blade, wherein
• the electromagnetic actuator comprises a rotor that is composed of a permanent magnet and that is rotatable in two directions between a first end position and a second end position via an intermediate position, a coil that is wound around the rotor and that rotates the rotor in an energizing state where an electric current is applied to the coil, and auto-retaining means for retaining the rotor at one of three positions selected from the intermediate position, the first end position and the second end position under a non-energizing state where the electric current is not applied to the coil, the auto-retaining means comprising an elastic member that regulates the rotor at the intermediate position by a mechanical elastic force, a first magnetic member that is opposed to the permanent magnet and that retains the rotor at the first end position by a magnetic attractive force, and a second magnetic member that is opposed to the permanent magnet and that retains the rotor at the second end position by a magnetic attractive force, and wherein
• the diaphragm blade is driven selectively to three positions for setting the aperture in a large diameter, a medium diameter and a small diameter, respectively, the three positions of the diaphragm blade corresponding to the three positions of the rotor.

An electromagnetic actuator comprising:

• a rotor that is magnetized in two poles and that is rotatable in two directions between a first end position and a second end position via an intermediate position;
• a yoke that has a horseshoe-like shape and that is arranged relative to the rotor such that a magnetic attractive force is created when the rotor comes to either of the first end position and the second end position;
• a coil that is wound around the yoke and that rotates the rotor in an energizing state where an electric current is applied to the coil;
• and
• auto-retaining means for retaining the rotor at one of the intermediate position, the first end position and the second end position under a non-energizing state where the electric current is not applied to the coil, wherein
• the auto-retaining means comprises an elastic member that regulates the rotor at the intermediate position by a mechanical elastic force, a first stopper member that arrests the rotor at the first end position by utilizing the magnetic attractive force created between the rotor and the yoke, and a second stopper member that arrests the rotor at the second end position by utilizing the magnetic attractive force created between the rotor and the yoke.

A shutter apparatus comprising:

• a shutter blade that is arranged on a substrate having an aperture and that opens and closes the aperture;
• and an electromagnetic actuator that is engaged with the shutter blade and that drives the shutter blade to open and close the aperture, wherein
• the electromagnetic actuator comprises a rotor that is magnetized in two poles and that is rotatable in two directions between a first end position and a second end position via an intermediate position, a yoke that has a horseshoe-like shape and that is arranged relative to the rotor such that a magnetic attractive force is created when the rotor comes to either of the first end position and the second end position, a coil that is wound around the yoke and that rotates the rotor in an energizing state where an electric current is applied to the coil, and auto-retaining means for retaining the rotor at one of three positions selected from the intermediate position, the first end position and the second end position under a non-energizing state where the electric current is not applied to the coil, the auto-retaining means comprising an elastic member that regulates the rotor at the intermediate position by a mechanical elastic force, a first stopper member that arrests the rotor at the first end position by utilizing the magnetic attractive force created between the rotor and the yoke, and a second stopper member that arrests the rotor at the second end position by utilizing the magnetic attractive force created between the rotor and the yoke, and wherein
• the shutter blade is driven to one of three positions selected from a full opening position for opening the aperture, a full closing position for closing the aperture, and a half opening position for partially opening the aperture, the three positions of the shutter blade corresponding to the three positions of the rotor.

A diaphragm apparatus comprising:

• a diaphragm blade that is arranged on a substrate having an aperture and that regulates a diameter of the aperture;
• and an electromagnetic actuator that is engaged with the diaphragm blade to drive the diaphragm blade, wherein
• the electromagnetic actuator comprises a rotor that is magnetized in two poles and that is rotatable in two directions between a first end position and a second end position via an intermediate position, a yoke that has a horseshoe-like shape and that is arranged relative to the rotor such that a magnetic attractive force is created when the rotor comes to either of the first end position and the second end position, a coil that is wound around the yoke and that rotates the rotor in an energizing state where an electric current is applied to the coil, and auto-retaining means for retaining the rotor at one of three positions selected from the intermediate position, the first end position and the second end position under a non-energizing state where the electric current is not applied to the coil, the auto-retaining means comprising an elastic member that regulates the rotor at the intermediate position by a mechanical elastic force, a first stopper member that arrests the rotor at the first end position by utilizing the magnetic attractive force created between the rotor and the yoke, and a second stopper member that arrests the rotor at the second end position by utilizing the magnetic attractive force created between the rotor and the yoke, and wherein
• the diaphragm blade is driven selectively to three positions for setting the aperture in a large diameter, a medium diameter and a small diameter, respectively, the three positions of the diaphragm blade corresponding to the three positions of the rotor.