US3643575A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Exposure-measuring device in a single-lens reflex camera
Assignee: Nikon Corp
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Filing: 1968-10-25
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Granted: 1972-02-22
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Expires: 1988-10-25
Abstract
Abstract An exposure meter system for a single-lens reflex camera which can function either by sensing the light passing through the maximum diaphragm opening of an interchangeable lens mounted on the camera or by sensing the light which has been restricted by the diaphragm of the interchangeable lens. Light from the interchangeable lens is directed through a relay optical system to a photocell. An adjustable aperture in the relay optical system is adapted to be connected to the diaphragm ring of the interchangeable lens to adjust the sensitivity of the photocell for different aperture ratios of different interchangeable lenses. When the adjustable aperture in the relay optical system is not connected, compensating means associated with the photocell are automatically actuated to enable the exposure meter system to operate by using the diaphragm of the interchangeable lens to control the light reaching the photocell.
Inventors
- 👤 Shigeo Ono
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 11:33
CPC Classifications
G; G03; G03B; G03B7/00; G03B7/08; G03B7/099; G03B7/0993; G03B7/0997; G03B7/09971; G03B7/09972
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
187 words
An exposure-correcting device for a single-lens reflex camera of the type having a retractable mirror constructed to receive interchangeable objective lenses, and having an exposure meter including a photosensitive element, a diaphragm for the interchangeable lenses, and a diaphragm-adjusting means, said device comprising a relay optical system having an adjustable aperture stop associated with the photosensitive element to restrict the light incident thereon; means connecting said diaphragm-adjusting means with the adjustable aperture stop whereby the adjustment of the aperture stop is responsive to the position of the diaphragm-adjusting means; said aperture stop adapted to be fully opened when said connecting means is disconnected from the diaphragm-adjusting means so that the light measurement is achieved by stopping down the diaphragm of the objective lens; and compensating means operatively associated with the photosensitive element to correct for the difference between the light intensity on the photosensitive element when the light is restricted by the aperture stop of said relay optical system in response to the connecting means and diaphragmadjusting means and when the light is restricted by the diaphragm of the objective lens when the connecting means is disconnected.
Claim 2
Dependent Claim
187 words
An exposure-correcting device for a single-lens reflex camera of the type having a retractable mirror constructed to receive interchangeable objective lenses, and having an exposure meter including a photosensitive element, a diaphragm for the interchangeable lenses, and a diaphragm-adjusting means, said device comprising a relay optical system having an adjustable aperture stop associated with the photosensitive element to restrict the light incident thereon; means connecting said diaphragm-adjusting means with the adjustable aperture stop whereby the adjustment of the aperture stop is responsive to the position of the diaphragm-adjusting means; said aperture stop adapted to be fully opened when said connecting means is disconnected from the diaphragm-adjusting means so that the light measurement is achieved by stopping down the diaphragm of the objective lens; and compensating means operatively associated with the photosensitive element to correct for the difference between the light intensity on the photosensitive element when the light is restricted by the aperture stop of said relay optical system in response to the connecting means and diaphragmadjusting means and when the light is restricted by the diaphragm of the objective lens when the connecting means is disconnected.
Claim 3
Dependent Claim
14 words
An exposure-correcting device according to claim 1, wherein the compensating means is a filter.
Claim 4
Dependent Claim
34 words
An exposure-correcting device according to claim 2, including means for mounting the filter for movement over and retraction away from the photosensitive element; and wherein the filter is normally maintained over the photosensitive element.
Claim 5
Dependent Claim
87 words
An exposure-correcting device according to claim 1, including a bridge circuit connected to the photosensitive element, the circuit comprising an adjustable resistor in an arm thereof and two arms each having a fixed resistor therein; and wherein the compensating means comprises a correcting resistor connected in parallel to one of said fixed resistors, and wherein the correcting resistor is connected to a switch, the switch being connected to the bridge circuit, the opening and closing of the switch being controlled by the position of the diaphragm-adjusting means.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-02-21 | 1975-08-23 | 1976-02-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-02-21 | 1979-08-23 | 1980-02-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-02-21 | 1983-08-23 | 1984-02-22 | $7700.00 | Window Closed / Lapsed |