US4437746A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Photo metering device for single lens reflex camera
Assignee: Canon Inc
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Filing: 1982-03-25
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Granted: 1984-03-20
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Expires: 2002-03-25
Abstract
Abstract In the disclosed device, light radiated from an object image formed on the focal plane by an objective lens is directed to a photo-cell using a condenser lens. The condenser lens has reflection areas formed in portions of the surfaces thereof. According to an embodiment, the surface closer to the oncoming light is mirrored at the central portion and the more remote surface is mirrored marginally. In another embodiment, the more remote area is recessed to receive the photo-cell.
Inventors
- 👤 Keiji Ikemori
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 12:44
CPC Classifications
G; G03; G03B; G03B7/00; G03B7/08; G03B7/099; G03B7/0993; G03B7/0997; G03B7/09971; G03B7/09972
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
117 words
A photo metering device for a single lens reflex camera comprising: (a) a photographic optical system for forming an object image on an image receiving means; (b) a photo sensor for receiving light from the object; (c) a biconvex condenser lens system arranged between said image receiving means and said photo sensor, and having a first spherical surface and a second spherical surface; (d) first reflective means formed on the center zone of said first spherical surface; and (e) second reflective means formed on the center zone of said second surface arranged so that light from the object image is reflected by said first reflective means and said second reflective means and directed to the photo sensor.
Claim 2
Dependent Claim
117 words
A photo metering device for a single lens reflex camera comprising: (a) a photographic optical system for forming an object image on an image receiving means; (b) a photo sensor for receiving light from the object; (c) a biconvex condenser lens system arranged between said image receiving means and said photo sensor, and having a first spherical surface and a second spherical surface; (d) first reflective means formed on the center zone of said first spherical surface; and (e) second reflective means formed on the center zone of said second surface arranged so that light from the object image is reflected by said first reflective means and said second reflective means and directed to the photo sensor.
Claim 3
Dependent Claim
40 words
A device as in claim 1, wherein said condenser lens system defines an optical axis, said condenser lens system being arranged symmetrically about the optical axis, and said marginal and said center zones being arranged symmetrically about the optical axis.
Claim 4
Dependent Claim
21 words
A device as in claim 2, wherein said lens system includes a plurality of elements, each having one of the surfaces.
Claim 5
Dependent Claim
19 words
A device as in claim 2, wherein said lens system includes a single element having the pair of surfaces.
Claim 6
Dependent Claim
31 words
A device as in claim 4, wherein said biconvex condenser lens system includes a central recess projecting into the first spherical surface and said photo sensor is located in said recess.
References Cited (Backward Citations)
US4174894A
Cited
US4170410A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-03-20 | 1987-09-19 | 1988-03-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-03-20 | 1991-09-19 | 1992-03-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-03-20 | 1995-09-19 | 1996-03-20 | $7700.00 | Window Closed / Lapsed |