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US 4,057,810 AGranted
Exposure control system
AssigneeWest Electric Company, Ltd.
InventorHiroshi Iwata
Life of this patent
Estimating the term…
Abstract
An exposure control device incorporates an electromagnetic driving device comprising a stator with a plurality of pairs of diametrically opposed poles each mounted with a field coil, a rotor made of a permanent magnet for rotation in either direction through a predetermined angle when one or more than one pairs of poles are magnetized depending upon the brightness of a subject, and means for converting the rotation of the rotor into the force for driving a plurality of shutter blades, which also function as the diaphragm, to open to define a predetermined aperture for a predetermined time depending upon the brightness of the subject.
Claims8
An exposure control system comprising
- a plurality of shutter blades which also function as the diaphragn blades,
- a driving device comprising
- a stator having a plurality of pairs of angularly separated opposed poles, field coils mounted on each pair of stator poles, and
- a rotor having a pair of poles one of which is magnetized to the N pole and the other is magnetized to the S pole, and positioned stationarily between one of said pairs of poles, which is located at the center of poles when said shutter blades are closed, means operatively connecting said rotor to said shutter blades;
- a plurality of switches, each connected to a different pair of said opposed field coils, switch selection means responsive to a control signal for selectively actuating different ones of said switches or pairs of said switches connected to adjacent field coils to establish a magnetic field within said stator at an angle having a one-to-one correlation with the value defined by said control signal, said magnetic field interacting with said rotor poles to generate a driving force to rotate said rotor into alignment with said magnetic field,
- aperture setting means responsive to the brightness of a subject for providing said control signal for actuating said switch selection means, said control signal being provided to said switch selection means prior to the actuation of said switches or pairs of switches by said selection means, thereby causing said shutter blades to define a predetermined aperture depending upon the brightness of said subject,
- exposure time setting means responsive to the brightness of said subject for controlling the operating time of said switch selection means;
- thereby controlling the opening time of said shutter blades depending on the brightness of said subject, and
- electrical power supply means for providing current to said switches, whereby said shutter blades are driven to define a predetermined aperture for a predetermined time depending upon the brightness of a subject, thereby attaining the optimum exposure.
6 more elements
An exposure control system comprising:
- a plurality of shutter blades which also function as the diaphragm blades;
- a driving device comprising (i) a stator having a plurality of pairs of angularly separated opposed poles, field coils mounted on each pair of stator poles, and (ii) a rotor having a pair of poles one of which is magnetized to the N pole and the other is magnetized to the S pole, and positioned stationarily between one of said pairs of poles, which is located at the center of poles when said shutter blades are closed, means operatively connecting said rotor to said shutter blades;
- a plurality of switches, each connected to a different pair of said opposed field coils, switch selection means responsive to a control signal for selectively actuating different ones of said switches or pairs of said switches connected to adjacent field coils, thereby establishing a magnetic field within said stator at an angle depending on said control signal,
- aperture setting means responsive to the brightness of a subject for providing said control signal for actuating said switch selection means, said aperture setting means comprising:
- (i) photometry circuit means for detecting the brightness of a subject and generating the integrated output representative of the brightness of the subject, i.e., the total value of brightness of the subject as a function of a time, pulse generator means for generating pulses with a predetermined pulse spacing and for applying said pulses to said switch selection means prior to the actuation of said plurality of switches, and (ii) means for interrupting the transmission of said pulses from said pulses generator means to said switch selection means when said integrated output reaches a predetermined value, thereby causing said shutter blades to define a predetermined aperture depending upon the brightness of said subject,
- exposure time setting means responsive to the brightness of said subject for controlling the operating time of said switch selection means;
- thereby controlling the opening time of said shutter blades depending on the brightness of said subject, and
- electrical power supply means for providing current to said switches, whereby said shutter blades are driven to define a predetermined aperture for a predetermined time depending upon the brightness of a subject, thereby attaining the optimum exposure.
5 more elements
An exposure control system comprising:
- a plurality of shutter blades which also function as the diaphragm blades;
- a driving device comprising (i) a stator having a plurality of pairs of angularly separated opposed poles, field coils mounted on each pair of stator poles, and (ii) a rotor having a pair of poles one of which is magnetized to the N pole and the other is magnetized to the S pole, and positioned stationarily between one of said pairs of poles, which is located at the center of poles when said shutter blades are closed, means operatively connecting said rotor to said shutter blades;
- a plurality of switches, each connected to a different pair of said opposed field coils, switch selection means responsive to a control signal for selectively actuating different ones of said switches or pairs of said switches connected to adjacent field coils, thereby establishing a magnetic field within said stator at an angle depending on said control signal;
- means operatively coupled between said driving device and said shutter blades for driving said shutter blades, said means comprising (i) two driving pin means attached to said rotor and spaced apart in either direction from the axis of said rotor by a suitable distance, (ii) an inverse cam means for engagement with said two driving pin means, (iii) return spring means attached to said inverse cam means for imparting the energy stored during the displacement of said inverse cam means to said inverse cam means, thereby causing said inverse cam means to return quickly to its initial position, and (iv) means operatively coupled between said inverse cam means and said shutter blades for transmitting the displacement of said inverse cam means to said shutter blades, thereby causing said shutter blades to open and close;
- aperture setting means responsive to the brightness of a subject for providing said control signal for actuating said switch selection means, thereby causing said shutter blades to define a predetermined aperture depending upon the brightness of said subject;
- exposure time setting means responsive to the brightness of said subject for controlling the operating time of said switch selection means;
- thereby controlling the opening time of said shutter blades depending on the brightness of said subject;
- and
- electrical power supply means for providing current to said switches, whereby said shutter blades are driven to define a predetermined aperture for a predetermined time depending upon the brightness of a subject, thereby attaining the optimum exposure.
6 more elements
An exposure control system comprising:
- a plurality of shutter blades which also function as the diaphragm blades;
- a driving device comprising (i) a stator having a plurality of pairs of angularly separated opposed poles, field coils mounted on each pair of stator poles, and (ii) a rotor having a pair of poles one of which is magnetized to the N pole and the other is magnetized to the S pole, and positioned stationarily between one of said pairs of poles, which is located at the center of poles when said shutter blades are closed, means operatively connecting said rotor to said shutter blades;
- a plurality of switches, each connected to a different pair of said opposed field coils, switch selection means responsive to a control signal for selectively actuating different ones of said switches or pairs of said switches connected to adjacent field coils, said switch selection means comprising (i) a plurality of comparators for comparing an input signal representative of the brightness of said subject with a reference signal and for providing a reversal of an output signal when the level of the input signal exceeds the level of the reference signal and (ii) a plurality of transistors operatively interconnected between said comparators and said field coils for selectively energizing said field coils in response to the reversal of said output signals, thereby establishing a magnetic field within said stator at an angle depending on said control signal;
- aperture setting means responsive to the brightness of a subject for providing said control signal for actuating said switch selection means, thereby causing said shutter blades to define a predetermined aperture depending upon the brightness of said subject;
- exposure time setting means responsive to the brightness of said subject for controlling the operating time of said switch selection means;
- thereby controlling the opening time of said shutter blades depending on the brightness of said subject;
- and
- electrical power supply means for providing current to said switches, whereby said shutter blades are driven to define a predetermined aperture for a predetermined time depending upon the brightness on a subject, thereby attaining the optimum exposure.
5 more elements
Dependencies are inferred from the claim text.