US3683765A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Apparatus to determine an amount of exposure
Assignee: Canon Inc
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Filing: 1970-01-22
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Granted: 1972-08-15
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Expires: 1990-01-22
Abstract
Abstract A single lens reflex camera having interchangeable lenses and an apparatus for determining the amount of exposure by measuring the light passing through the fully opened aperture of the lens, in which a diaphragm aperture is preset by setting a preset diaphragm aperture setting ring, having a graduated aperture scale of equal spacing, and the starting point of the movement stroke of the ring is set at a fixed position irrespective of the extent of the maximum aperture of an interchangeable lens, and thus the scale for the maximum aperture of the lens comes to the fixed position, which is characterized by an integral coupling member provided on the above-mentioned preset aperture setting ring or to a preset cam engaged with the ring, and at the same time a correction projection, having such a different length as to correct the apparatus referring to the maximum aperture of the interchangeable lens, is provided at the lens so that when the lens is mounted on a camera, the projection makes such correction as compensating for a drop in value in the light measurement with a full-open aperture by a large aperture lens.
Inventors
- 👤 Yukio Iura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 22:35
CPC Classifications
G; G03; G03B; G03B7/00; G03B7/003; G03B7/20
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
226 words
An apparatus for determining the amount of exposure for a single lens reflex camera comprising an interchangeable lens having a variable diaphragm, a preset diaphragm aperture setting ring rotatably assembled on said lens, a pin provided on said preset ring, an exposure meter having an indicating means and a light receiving element which receives light passing through the lens with a full-open aperture, a means in engagement with said pin for transmitting the diaphragm aperture value from said preset ring, said means including a frame and cam means movably displaceable on said frame, a lever for the diaphragm aperture value rotatably connected to said frame, said means arranged to engage said pin at a fixed position irrespective of the extent of the maximum aperture of the lens when the lens with a full-open aperture is mounted on the camera for transmitting the movement stroke of said preset ring to said lever for the diaphragm aperture value, and a correction projection positioned on said interchangeable lens for providing a correction which compensates for the drop in light receiving value caused by vignetting and the like in said lens, said correction projection arranged to displace said lever for the diaphragm aperture value when said lens is mounted on the camera and to shift said lever by the amount corresponding to the correction for correcting the diaphragm aperture value.
Claim 2
Independent Claim
226 words
An apparatus for determining the amount of exposure for a single lens reflex camera comprising an interchangeable lens having a variable diaphragm, a preset diaphragm aperture setting ring rotatably assembled on said lens, a pin provided on said preset ring, an exposure meter having an indicating means and a light receiving element which receives light passing through the lens with a full-open aperture, a means in engagement with said pin for transmitting the diaphragm aperture value from said preset ring, said means including a frame and cam means movably displaceable on said frame, a lever for the diaphragm aperture value rotatably connected to said frame, said means arranged to engage said pin at a fixed position irrespective of the extent of the maximum aperture of the lens when the lens with a full-open aperture is mounted on the camera for transmitting the movement stroke of said preset ring to said lever for the diaphragm aperture value, and a correction projection positioned on said interchangeable lens for providing a correction which compensates for the drop in light receiving value caused by vignetting and the like in said lens, said correction projection arranged to displace said lever for the diaphragm aperture value when said lens is mounted on the camera and to shift said lever by the amount corresponding to the correction for correcting the diaphragm aperture value.
Claim 3
Dependent Claim
94 words
An apparatus, as set forth in claim 1, wherein said cam means comprises a plate having a cam surface, said plate is slidably supported on said frame, a sliding piece slidably mounted on said frame is arranged in engagement with said correction projection for slidable displacement by said correction projection based on the correction for said interchangeable lens, said lever is pivotally attached to said sliding piece, and a spring biases said lever against the cam surface on said plate so that said lever is pivotally displaced as said plate slides on said frame.
Claim 4
Dependent Claim
175 words
An apparatus, as set forth in claim 1, wherein said cam means comprises a slidably mounted cam member, said indicating means on said exposure meter comprises an indicator arranged to swing into position depending on the amount of light received by said light receiving element after the light passes through the lens with the full-open aperture, a sliding piece slidably mounted on said frame is arranged in engagement with said correction projection for slidable displacement by said correction projection based on the correction for said interchangeable lens, said lever is pivotally attached to said sliding piece, said cam member for the diaphragm aperture value is arranged in engagement with said pin for displacement due to the movement stroke of said preset ring, spring means for biasing said lever into contact with said cam member so that said lever can be pivoted about its attachment to said sliding piece by said cam member for indicating that the diaphragm is presEt at an optimum value when said lever is overlapped by said indicator of said exposure meter.
Claim 5
Dependent Claim
218 words
An interchangeable lens arrangement for a single lens reflex camera comprising an interchangeable lens having a variable diaphragm, a preset ring rotatably assembled on said lens, a pin provided on said preset ring, a shutter speed setting device including a photoconductive element which receives light passing through the lens with a full-open aperture, means in engagement with said pin for transmitting the diaphragm aperture value from said preset ring, said means including a frame and a first plate movably displaceable on said frame, a second plate for the diaphragm aperture value rotatably connected to said frame, said means being arranged in engagement with said pin at a fixed position irrespective of the extent of the maximum aperture of said lens when said lens is mounted on a camera with a full-open aperture for transmitting the movement stroke of said preset ring to said plate for the diaphragm aperture value, a correction projection positioned on said interchangeable lens and providing a correction which compensates for the decrease in light receiving value caused by vignetting and the like in the lens, said correction projection arranged to engage said second plate for the diaphragm aperture value when said lens is mounted on the camera for compensating the signal of the diaphragm aperture value corresponding to the correction of said correction projection.
Claim 6
Dependent Claim
218 words
An interchangeable lens arrangement for a single lens reflex camera comprising an interchangeable lens having a variable diaphragm, a preset ring rotatably assembled on said lens, a pin provided on said preset ring, a shutter speed setting device including a photoconductive element which receives light passing through the lens with a full-open aperture, means in engagement with said pin for transmitting the diaphragm aperture value from said preset ring, said means including a frame and a first plate movably displaceable on said frame, a second plate for the diaphragm aperture value rotatably connected to said frame, said means being arranged in engagement with said pin at a fixed position irrespective of the extent of the maximum aperture of said lens when said lens is mounted on a camera with a full-open aperture for transmitting the movement stroke of said preset ring to said plate for the diaphragm aperture value, a correction projection positioned on said interchangeable lens and providing a correction which compensates for the decrease in light receiving value caused by vignetting and the like in the lens, said correction projection arranged to engage said second plate for the diaphragm aperture value when said lens is mounted on the camera for compensating the signal of the diaphragm aperture value corresponding to the correction of said correction projection.
Claim 7
Dependent Claim
80 words
An interchangeable lens arrangement, as set forth in claim 4, wherein said shutter speed setting device comprises an input circuit for the diaphragm aperture information coupled to said second plate for the diaphragm aperture value, a light measuring circuit connected to said photoconductive element, another input circuit composed of a comparison circuit for the output of said diaphragm aperture information input circuit and the output of said light measuring circuit, and a shutter speed setting circuit containing a switching circuit.
Claim 8
Dependent Claim
53 words
An interchangeable lens arrangement, as set forth in claim 5, wherein a resistor is mounted on said second plate, a contact arm is positioned on said first plate for the diaphragm aperture value in sliding engagement with said resistor, and said resistor being connected to said input circuit for the diaphragm aperture information.
Claim 9
Dependent Claim
163 words
An interchangeable lens arrangement, as set forth in claim 6, wherein said first plate by means of said pin moves together with the movement stroke of said preset ring, said contact arm mounted on said first plate slides above said resistor on said second plate for transmitting the information of the diaphragm aperture value to said second plate, said second plate being moved through said first plate by said correction projection of said interchangeable lens and said resistor mounted on said second plate transmits to said diaphragm aperture information input circuit the information of the diaphragm aperture correction corresponding to the correction of said correction projection; said photoconductive element which receives the light passing through the interchangeable lens with a full-open aperture inputs the information of the aperture value to said light measuring circuit, and said comparison circuit inputs the information of both of the diaphragm aperture and the aperture value to said shutter speed setting circuit for setting an optimum exposure value.
References Cited (Backward Citations)
US3082672A
Cited
US3503313A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-08-15 | 1976-02-14 | 1976-08-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-08-15 | 1980-02-14 | 1980-08-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-08-15 | 1984-02-14 | 1984-08-15 | $7700.00 | Window Closed / Lapsed |