US3864699A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic exposure control system for ttl metering type single-lens reflex camera
Assignee: Canon Inc
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Filing: 1973-09-06
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Granted: 1975-02-04
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Expires: 1993-09-06
Abstract
Abstract In the TTL metering type single-lens reflex camera, a photoelectric converter element disposed for receiving light from a viewfinder''s optical system and a photoelectric converter element disposed outwardly of such optical system for receiving light reflected from a shutter curtain or a film surface after flip-up of the viewing mirror are parallel-connected and have characteristics selected to be substantially equal so that the rising and falling electrical properties of these elements are utilized to accomplish a smooth transition of exposure control.
Inventors
- 👤 Tokuichi Tsunekawa
- 👤 Soichi Nakamoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 14:08
CPC Classifications
G; G03; G03B; G03B19/00; G03B19/02; G03B19/12; G03B7/00; G03B7/08; G03B7/099; G03B7/0993; G03B7/0997; G03B7/09971; G03B7/09974; G03B7/09976
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
172 words
An automatic exposure control system for a through-the-lens photometry type single-lens reflex camera comprising: a finder optical system having a movable mirror; a first photoelectric converter element having a surface for receiving a light flux passing through said finder optical system; a second photoelectric converter element disposed outside of the light path of said finder optical system and having a surface for receiving a light flux reflected by at least one of a shutter curtain and a film surface, the electrical response properties of the second photoelectric converter element being selected to be substantially the same as those of the first photoelectric converter element and those two elements being connected in parallel with each other; and means for controlling the exposure including said parallelconnected first and second photoelectric converter elements and controlling the exposure by simultaneously utilizing the response rise property of said first photoelectric converter element and the response fall-off characteristic of said second photoelectric converter characteristic during transfer of exposure control from one of said converter elements to the other.
Claim 2
Dependent Claim
172 words
An automatic exposure control system for a through-the-lens photometry type single-lens reflex camera comprising: a finder optical system having a movable mirror; a first photoelectric converter element having a surface for receiving a light flux passing through said finder optical system; a second photoelectric converter element disposed outside of the light path of said finder optical system and having a surface for receiving a light flux reflected by at least one of a shutter curtain and a film surface, the electrical response properties of the second photoelectric converter element being selected to be substantially the same as those of the first photoelectric converter element and those two elements being connected in parallel with each other; and means for controlling the exposure including said parallelconnected first and second photoelectric converter elements and controlling the exposure by simultaneously utilizing the response rise property of said first photoelectric converter element and the response fall-off characteristic of said second photoelectric converter characteristic during transfer of exposure control from one of said converter elements to the other.
Claim 3
Dependent Claim
42 words
An automatic exposure control system for a through-the-lens photometry type single-lens reflex camera according to claim 1, in which said surface of the second photoelectric converter element receives light flux reflected from a film surface at the time of the shutter opening.
Claim 4
Dependent Claim
39 words
An automatic exposure control system for a through-the-lens photometry type single-lens reflex camera according to claim 2, in which a light quantity controlling element is disposed in front of said light receiving surface of the first photoelectric converter element.
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) | 1978-02-03 | 1978-08-05 | 1979-02-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-03 | 1982-08-05 | 1983-02-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-03 | 1986-08-05 | 1987-02-04 | $7700.00 | Window Closed / Lapsed |