Abstract: A reduction gear includes a reduction mechanism, which includes: an external gear eccentrically rotatable about an input shaft; an internal gear internally meshing with the external gear and having a small number of difference between the teeth of the internal gear and the external gear; a disk for extracting only a rotational component of the external gear; an output shaft; and gears for transmitting the rotational component of the external gear from the disk to the output shaft. The disk, the gears and the output shaft are aligned in a direction perpendicular to an axial direction of the input shaft.

Abstract: An electromagnetic actuator with a smaller size and an increased strength is provided. In the electromagnetic actuator, a first arm portion and a second arm portion that connect the magnetic poles of a stator extend to the outside of a rotor housing. A first coil and a second coil are wound around the extending portions. In other words, the first coil and the second coil are exposed to the outside of the rotor housing. Accordingly, compared with a case where the rotor housing also houses the first coil and the second coil, the width of the electromagnetic actuator can be reduced by the thickness of the rotor housing. Thus, the electromagnetic actuator can be made compact.

Abstract: A shutter for an optical apparatus has multiple sectors and an operation member. Each of the multiple sectors has a cam opening for engagement and is pivotally provided to open and close a shutter opening, the operation member moves each of said multiple sectors in engagement with the cam opening, and the cam opening of at least one sector that is one of the multiple sectors is formed to change a moving direction of said at least one sector, when the operation member moves said at least one sector to a position to close the shutter opening.

Abstract: A step motor includes a rotor having four magnetic poles, a first magnetic pole magnetically excited by a first coil, a second magnetic pole magnetically excited by a second coil, and a third magnetic pole magnetically excited by the first coil and the second coil. A gap between the third magnetic pole and the rotor is smaller than that between the first magnetic pole and the rotor and that between the second magnetic pole and the rotor. In the step motor, it is possible to intensify the influence, on the rotor having four poles, of the magnetic fields created from three magnetic poles. Accordingly, this can weaken the magnetic fields set up from the first magnetic pole and the second magnetic pole, which tend to intensify the influence on the rotor, enabling the torque smaller at the time of the rotation start of the rotor.

Abstract: A step motor includes a rotor having four magnetic poles, a first magnetic pole magnetically excited by a first coil, a second magnetic pole magnetically excited by a second coil, and a third magnetic pole magnetically excited by the first coil and the second coil. A gap between the third magnetic pole and the rotor is smaller than that between the first magnetic pole and the rotor and that between the second magnetic pole and the rotor. In the step motor, it is possible to intensify the influence, on the rotor having four poles, of the magnetic fields created from three magnetic poles. Accordingly, this can weaken the magnetic fields set up from the first magnetic pole and the second magnetic pole, which tend to intensify the influence on the rotor, enabling the torque smaller at the time of the rotation start of the rotor.

Abstract: A sector drive mechanism includes an electromagnetic actuator including a rotor having four polarities, a C-shaped stator, and a current control portion that controls current applied to a first coil and a second coil, the C-shaped stator including a first magnetic pole magnetically excited by the first coil, a second magnetic pole magnetically excited by the second coil, and a third magnetic pole magnetically excited by the first coil and the second coil, and sectors that are connected to the electromagnetic actuator to open and close a shutter opening provided in a substrate. The first coil and the second coil are driven to close the shutter opening with a fewer number of pulses applied from the current control portion than the number of the pulses to open the shutter opening.

Abstract: An aperture apparatus includes a substrate having a lens opening, a first aperture sector having a first aperture opening, a second aperture sector having a second aperture opening, and a drive pin that is engaged in cam openings respectively formed in the first aperture sector and in the second aperture sector and that swings the first aperture sector and the second aperture sector. The first aperture sector and the second aperture sector are located in receding positions from the lens opening, when the drive pin is in an initial position. The cam openings include a swing region and a non-swing region, the swing region guiding a corresponding sector to the lens opening as the drive pin moves from the initial position, the non-swing region retaining the other sector in the receding position, when one of the first aperture sector and the second aperture sector is guided to the lens opening.

Abstract: A step motor includes a rotor having four magnetic poles, a first magnetic pole magnetically excited by a first coil, a second magnetic pole magnetically excited by a second coil, and a third magnetic pole magnetically excited by the first coil and the second coil. A gap D between the third magnetic pole and the rotor is larger than a gap d between the first magnetic pole and the rotor and the gap d between the second magnetic pole and the rotor, so that a magnetic attraction is generated between a pole of the rotor and the first magnetic pole and between another pole of the rotor and the second magnetic pole. With this step motor applied to a shutter driving mechanism of a camera, it is possible to surely retain the shutter state even when the current does not flow.

Abstract: An aperture apparatus includes a substrate having a lens opening, a first aperture sector having a first aperture opening, a second aperture sector having a second aperture opening, and a drive pin that is engaged in cam openings respectively formed in the first aperture sector and in the second aperture sector and that swings the first aperture sector and the second aperture sector. The first aperture sector and the second aperture sector are located in receding positions from the lens opening, when the drive pin is in an initial position. The cam openings include a swing region and a non-swing region, the swing region guiding a corresponding sector to the lens opening as the drive pin moves from the initial position, the non-swing region retaining the other sector in the receding position, when one of the first aperture sector and the second aperture sector is guided to the lens opening.

Abstract: There is provided a shutter apparatus including a substrate having a shutter opening and at lease two sectors that are supported by spindles swingably and that open and close the shutter opening, and a spindle of one sector of the at lease two sectors is located in a swinging range of another sector of the at lease two sectors, and is a pin of a rod-shaped member formed on the substrate to be lower in an overall height than a height in which the another sector swings.

Abstract: A step motor includes a rotor having four magnetic poles, a first magnetic pole magnetically excited by a first coil, a second magnetic pole magnetically excited by a second coil, and a third magnetic pole magnetically excited by the first coil and the second coil. A gap between the third magnetic pole and the rotor is smaller than that between the first magnetic pole and the rotor and that between the second magnetic pole and the rotor. In the step motor, it is possible to intensify the influence, on the rotor having four poles, of the magnetic fields created from three magnetic poles. Accordingly, this can weaken the magnetic fields set up from the first magnetic pole and the second magnetic pole, which tend to intensify the influence on the rotor, enabling the torque smaller at the time of the rotation start of the rotor.

Abstract: A step motor includes a rotor having four magnetic poles, a first magnetic pole magnetically excited by a first coil, a second magnetic pole magnetically excited by a second coil, and a third magnetic pole magnetically excited by the first coil and the second coil. A gap D between the third magnetic pole and the rotor is larger than a gap d between the first magnetic pole and the rotor and the gap d between the second magnetic pole and the rotor, so that a magnetic attraction is generated between a pole of the rotor and the first magnetic pole and between another pole of the rotor and the second magnetic pole. With this step motor applied to a shutter driving mechanism of a camera, it is possible to surely retain the shutter state even when the current does not flow.

Abstract: A sector drive mechanism includes an electromagnetic actuator including a rotor having four polarities, a C-shaped stator, and a current control portion that controls current applied to a first coil and a second coil, the C-shaped stator including a first magnetic pole magnetically excited by the first coil, a second magnetic pole magnetically excited by the second coil, and a third magnetic pole magnetically excited by the first coil and the second coil, and sectors that are connected to the electromagnetic actuator to open and close a shutter opening provided in a substrate. The first coil and the second coil are driven to close the shutter opening with a fewer number of pulses applied from the current control portion than the number of the pulses to open the shutter opening.

Abstract: A shutter for an optical apparatus has multiple sectors and an operation member. Each of the multiple sectors has a cam opening for engagement and is pivotally provided to open and close a shutter opening, the operation member moves each of said multiple sectors in engagement with the cam opening, and the cam opening of at least one sector that is one of the multiple sectors is formed to change a moving direction of said at least one sector, when the operation member moves said at least one sector to a position to close the shutter opening.

Abstract: An electromagnetic actuator has a rotor and a stator around which coils are wound to face portions of an outer surface of the rotor. The stator is C-shaped, the rotor is arranged so that a rotation axis thereof is existent in a space surrounded by the stator, and both ends of the stator are respectively formed within a range from 15 to 90 degrees from a virtual base line with respect to the rotation axis serving as a center, when the virtual base line is set to run a center of the rotation axis and separate the stator into left and right.

Abstract: A step motor includes a rotor having four magnetic poles, a first magnetic pole magnetically excited by a first coil, a second magnetic pole magnetically excited by a second coil, and a third magnetic pole magnetically excited by the first coil and the second coil. A gap between the third magnetic pole and the rotor is smaller than that between the first magnetic pole and the rotor and that between the second magnetic pole and the rotor. In the step motor, it is possible to intensify the influence, on the rotor having four poles, of the magnetic fields created from three magnetic poles. Accordingly, this can weaken the magnetic fields set up from the first magnetic pole and the second magnetic pole, which tend to intensify the influence on the rotor, enabling the torque smaller at the time of the rotation start of the rotor.

Abstract: An electromagnetic actuator with a smaller size and an increased strength is provided. In the electromagnetic actuator, a first arm portion and a second arm portion that connect the magnetic poles of a stator extend to the outside of a rotor housing. A first coil and a second coil are wound around the extending portions. In other words, the first coil and the second coil are exposed to the outside of the rotor housing. Accordingly, compared with a case where the rotor housing also houses the first coil and the second coil, the width of the electromagnetic actuator can be reduced by the thickness of the rotor housing. Thus, the electromagnetic actuator can be made compact.