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US 4,174,161 AGranted
Exposure control system
AssigneeCanon Kabushiki Kaisha
InventorsYukio Mashimo, Takashi Uchiyama, Kanehiro Sorimachi
Life of this patent
Estimating the term…
Abstract
In the exposure control system disclosed, a first photoelectric element responds to light from a scene to be photographed. A second photoelectric element is a spot sensor set to respond from a portion of the scene to be photographed. An exposure control circuit which is coupled to the first and second photoelectric elements controls the shutter and aperture on the basis of at least the relationship between the responses of the first and second photoelectric elements.
Claims19
An exposure control system for a scene having a main portion and a remaining portion, comprising
- (A) flash illumination means for emitting an auxiliary light to illuminate at least a main portion of a scene to be photographed;
- (B) exposure control means including
- (b1) exposure aperture means adjustable to an aperture for obtaining an appropriate flash exposure in response to the distance to the main portion, said exposure control means including
- (b2) shutter means for providing an exposure for a variable time and for actuating said flash illumination means on a synchronous basis;
- (C) control circuit having
- (c1) a light receiving element for generating an electrical signal in response to an amount of light from substantially the remaining portion of the scene and
- (c2) time defining means for determining the time of said shutter means on the basis of the output of said element and the adjusted aperture value so as to produce an appropriate exposure for substantially the remaining portion of the scene;
- and
- (D) limiter means for preventing the shutter from being adjusted beyond a predetermined time.
6 more elements
An exposure control system for a camera for affording an appropriate overall exposure when an object is illuminated with a flash, comprising:
- flash illumination means, a focusing device for a photographing lens, exposure control means having aperture adjusting means for adjusting the aperture diameter, shutter means synchronized with said flash illumination means for exposing a film through said exposure aperture means, control circuit means having a photoelectric conversion element for measuring the overall brightness and converting it into a quantity of electricity, an electromagnetic member displaceable over a movable range in response to a quantity of electricity being applied and adjustably determining the shutter opening of said shutter means as well as the opening of exposure aperture means respectively in response to an amount of displacement of said member, control means having a reference member which is displaceable within the movable range of the electromagnetic member, said reference member being connected with the focusing device to be displaced by operation of the focusing device.
An exposure control system for a camera mechanism for affording an appropriate overall exposure of a scene being photographed, comprising flash illumination means, exposure control means including a shutter means combined with an iris device forming a diaphragm aperture during opening of the shutter means, trigger circuit means for said flash illumination means;
- said circuit means having variable resistor means variable by said focusing means, a capacitor forming a time constant circuit connected with said variable resistor means, switching means having an input connected with a terminal of said capacitor, said illumination means being triggered by said switching means, and a short-circuiting switch across said capacitor and coupled to be opened by opening of said exposure control device with a control circuit for controlling the opening and closing time of said exposure control means;
- time control circuit including a photoelectric conversion element responsive to the brightness of a scene for producing a quantity of electricity in response to intensity of illumination of an object being photographed, a second capacitor for a constant circuit connected with said photoelectric conversion element, a short-circuiting switch of said second capacitor, said switch being opened and closed in response to the opening and closing action of said exposure control means, the second switching means being connected its input with a terminal of said second capacitor, and a retaining means being connected with said switching means for closing a shutter means by actuation of said switching means, wherein said flash light illumination means is illuminated wherein said shutter means reaches an opening responding to the main object portion of an object to be photographed, and said shutter means is closed after the time corresponding to an average photometry value of an object to be photographed.
An exposure control system for a camera having a flash comprising:
- first circuit means including a photoelectric member responsive to light from the scene being photographed, second circuit means coupled to the flash for providing an electrical value corresponding to light upon a photographic subject of the scene, third circuit means including a signal means for causing said signal means to produce a signal representing an exposure factor in dependence upon electrical condition on said second circuit means, switch means coupled to each of said circuit means for alternately coupling said first circuit means and said second circuit means to said third circuit means so that said first and second circuit means alternately vary the electrical conditions in said third circuit means on the basis of conditions in said first and second circuit means and variable means in one of said circuit means and responsive to a second exposure factor for varying the electrical conditions in the one of said circuit means so that the signals for each position of the switch means can be made equal to each other.
For operation with various shutter speeds and diaphragm values as well as other exposure factors, in response to light from an object and for use with a flash device, a camera comprising:
- first exposure control circuit means for obtaining a first electrical signal corresponding to a diaphragm value for appropriate exposure in a daylight mode and based on other exposure values to be preset, the said exposure control circuit means having;
- a photo transducing element adapted to receive light from an object,
- presetting means for presetting another exposure value, and
- a control circuit operatively connected with the transducing element and the presetting means for forming the first electrical signal;
- second exposure control circuit means for obtaining a second electrical signal corresponding to the diaphragm value for proper exposure in a flash mode based on light emission from the flash device;
- selecting means for selecting one of the first exposure control circuit means and the second exposure control means;
- and
- indicating means connectable with one of the first exposure control circuit means and the second exposure control circuit means through the selecting means, for indicating the diaphragm value for appropriate exposure through the adjustment of the presetting means in the daylight and flash light modes.
5 more elements
An exposure control system for a camera and a flash device comprising:
- (A) exposure control means for defining an aperture;
- (B) aperture means operatively connected said exposure control means so as to be automatically adjusted thereby;
- (C) said exposure control means including
- (c1) first circuit means having a photoelectric conversion element for converting a brightness of the overall scene into an electrical signal and shutter speed information setting means,
- (c2) second exposure control circuit means having a variable register means variable in response to the distance to the principal object of the scene,
- (c3) exposure defining means operatively associated with said aperture means, the defining means having an electro-mechanical transducing means to produce a mechanical displacement by applying an electrical signal therein,
- (c4) switching means for selectively connecting said exposure defining means with said first circuit means and second circuit means;
- (D) said aperture means being operatively associated with the electro-mechanical transducing means for adjusting the aperture thereof responsive to the displacement.
5 more elements
Dependencies are inferred from the claim text.