Optical: systems and elements – Image stabilization – By movable refractive structure
Reexamination Certificate
1999-09-29
2001-05-01
Sikder, Mohammad Y. (Department: 2872)
Optical: systems and elements
Image stabilization
By movable refractive structure
C359S554000, C359S555000, C359S556000, C359S837000, C359S694000
Reexamination Certificate
active
06226124
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a tremble correcting apparatus which corrects a tremble, caused by a hand tremble and so on, of a focused image of an optical device.
2. Description of the Related Art
Conventionally, an optical device, such as a pair of binoculars, is provided with a tremble correcting apparatus, which corrects a tremble of a focused image caused by a hand tremble and so on. The tremble correcting apparatus comprises a correcting optical system. The correcting optical system is moved in a direction and by a predetermined amount such that a movement of the optical device is canceled, so that the tremble of the focused image is corrected.
As a driving apparatus which drives the correcting optical system, a ste ping motor,for example,isutilized. The stepping motor comprises a rotor, a stator and a coil. The stator is disposed around the rotor. The coil is wound around the stator. When an electric current flows through the coil, the stator is excited, so that the rotor rotates due to attractive and repulsive magnetic forces generated between the excited stator and the rotor. Accordingly, a rotating amount and a rotational direction of the rotor are determined by controlling the electric current which flows through the coil.
A transmitting mechanism changes a rotational movement of the rotor to a linear movement on a plane perpendicular to an optical axis of the correction optical system, before transmitting the rotational movement to the correction optical system. A driving amount of the correction optical system corresponding to one step rotation of the stepping motor, is detemined by an angular degree of the one step rotation of the stepping motor and a construction of the transmitting mechanism. Accordingly, the driving amount of the correction optical system is determined by controlling a step number of the rotation of the stepping motor. Further, a positional data of the correction optical system is detected based on an accumulation of the step number.
When the tremble of the optical device is not detected and it is not necessary to drive the correction optical system, the rotor should be fixed at a current rotational position. The excited state of the stator should be maintained in order to enable the rotor to be fixed at the current rotational position, and thus the electric current is continually passed through the coil. Namely, if the stepping motor is utilized as the driving mechanism of the correction optical system, it is necessary to continually keep the electric current turned on even if the correction optical system is not driven. Accordingly, the utilization of the stepping motor causes a large electric power consumption, and it is therefore uneconomical.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a tremble correcting device by which the electric power consumption is reduced.
In accordance with an aspect of the present invention, there is provided a tremble correcting device comprising: a detector that detects a trembling amount of an optical device; a correcting optical system that corrects a tremble of a focused image due to the optical device tremble; and a driving system that includes a stepping motor and a transmitting mechanism, disposed between the stepping motor and the correcting optical system, that converts a rotational movement of the stepping motor to a movement of the correcting optical system; and a controlling system that controls the driving system. The driving system drives the correcting optical system by a predetermined amount per one step. The controlling system controls the driving system such that, when a difference between the trembling amount detected by the detector and a position data of the correcting optical system, calculated based on a one step driving amount of the driving system, reaches a predetermined threshold, the driving device is driven to cancel the difference by controlling a driving electric current flowing in a coil of the stepping motor. When the difference is less than the predetermined threshold, the coil is electrically de-energized by the controlling system.
When the difference reaches the predetermined threshold, the coil is electrically energized by the controlling system such that a rotor of the stepping motor rotates by a predetermined angular amount unit.
When the coil is electrically de-energized and an external force applied to the optical device is transmitted by the stepping motor through the transmitting system, the external force is partially dissipated by the transmitting system so as to be less than a detent torque of the rotor of the stepping motor.
The tremble correcting device further comprises: a driving circuit that controls the driving electric current; and a switch that switches an electrical power supply to the driving circuit. The controlling system controls the switch, so that the electrical power supply is one of started and stopped.
When the difference reaches the predetermined threshold and the electric power supply is stopped, the controlling system starts the electric power supply such that the driving electric current flows in the coil in a direction similar to a direction of flow before the stopping of the electric power supply; and when the difference reaches the predetermined threshold and when the electric power is supplied, the controlling system controls a direction of flow of the driving electric current in the coil such that the difference is canceled by driving the stepping motor.
When the difference reaches the predetermined threshold and the electric power supply is stopped, the controlling system controls a direction of flow of the driving electric current in the coil such that the difference is canceled by driving the stepping motor, after starting the electric power supply.
The optical device is a pair of binoculars that includes a pair of telephoto optical systems. The transmitting mechanism is a screw feeder mechanism.
In accordance with another aspect of the present invention, there is provided a tremble correcting device comprising: a detector that detects an amount of an optical device tremble; a correcting optical system that corrects a tremble of a focused image due to the optical device tremble; and a driving system that includes a stepping motor and a transmitting mechanism in which a driving amount of an object driven by the stepping motor is relatively small in comparison with a rotational amount of the stepping motor, and deceleration of which is large; and a controlling system that controls the driving system. The transmitting mechanism is disposed between the stepping motor and the correcting optical system. The controlling system controls the driving system such that, when a difference between the trembling amount detected by the detector and a position data of the correcting optical system, calculated based on a one step driving amount of the driving system, reaches a predetermined threshold value, the driving device is driven to cancel the difference by controlling a flow of driving electric current in a coil of the stepping motor. When the difference is less than the predetermined threshold value, the coil is electrically de-energized by the controlling system.
The predetermined deceleration is pre-set such that an external torque, generated by an external force applied to the optical device being transmitted to the stepping motor through the correcting optical system, is less than a detent torque of the stepping motor at rest.
The optical device is a pair of binoculars that includes a pair of telephoto optical systems. The transmitting mechanism is a screw feeder mechanism.
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Enomoto Shigeo
Tsukamoto Shinji
Asahi Kogaku Kogyo Kabushiki Kaisha
Greenblum & Bernstein P.L.C.
Sikd-er Mohammad Y.
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