Patent US4146319A successfully refreshed from Google Patents.
US4146319A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Single lens reflex camera with automatic exposure control circuit
Assignee: Fujinon Corp
•
Filing: 1977-02-09
•
Granted: 1979-03-27
•
Expires: 1997-02-09
Abstract
Abstract A single lens reflex camera with an automatic exposure control circuit includes a photodetector and a light emitting indicator in the viewfinder optical system. The light emitting indicator is energized to emit light with high luminance for a predetermined period when the electric power source is turned on in the camera. By the high luminance light emission of the light emitting indicator, the photodetector in the exposure control circuit is preliminarily exposed to light before it starts to measure scene brightness. Thus, the response of the photodetector is enhanced.
Inventors
- 👤 Saburo Numata
- 👤 Shinichiro Okazaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 12:34
CPC Classifications
G; G03; G03B; G03B17/00; G03B17/18; G03B17/20
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
123 words
A single lens reflex camera with an automatic exposure control circuit wherein exposure is controlled by the output of a light measuring circuit including a photodetector provided in a viewfinder optical system and the controlled exposure is indicated in the viewfinder by means of a light emitting indicator, wherein the improvement comprises means provided for energizing said light emitting indicator to initally cause the same to emit light with high luminance regardless of scene brightness for a predetermined period when the electric power source for the exposure control circuit is turned on and thereafter cause the same to emit light with luminance determined according to scene brightness, whereby said photodetector is always preliminarily exposed to light upon turning on of the power source.
Claim 2
Dependent Claim
123 words
A single lens reflex camera with an automatic exposure control circuit wherein exposure is controlled by the output of a light measuring circuit including a photodetector provided in a viewfinder optical system and the controlled exposure is indicated in the viewfinder by means of a light emitting indicator, wherein the improvement comprises means provided for energizing said light emitting indicator to initally cause the same to emit light with high luminance regardless of scene brightness for a predetermined period when the electric power source for the exposure control circuit is turned on and thereafter cause the same to emit light with luminance determined according to scene brightness, whereby said photodetector is always preliminarily exposed to light upon turning on of the power source.
Claim 3
Dependent Claim
73 words
A single lens reflex camera with an automatic exposure control circuit according to claim 1 wherein a luminance changing circuit is connected with the light emitting indicator and a pulse generator which is reset upon turning on of the power source is connected with a luminance changing circuit to supply a pulse of a predetermined width thereto to cause the light emitting indicator to emit light with high luminance for a predetermined period.
Claim 4
Dependent Claim
22 words
A single lens reflex camera with an automatic exposure control circuit according to claim 2 wherein said predetermined period is several milliseconds.
Claim 5
Dependent Claim
55 words
A single lens reflex camera with an automatic exposure control circuit according to claim 2 wherein said luminance changing circuit is connected with the output of the light measuring circuit so that the luminance changing circuit controls the luminance of the light emitting indicator according to the scene brightness measured by the light measuring circuit.
References Cited (Backward Citations)
US3127823A
Cited
US3528350A
Cited
US3955892A
Cited
US3860936A
Cited
US4001845A
Cited
US3997904A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-03-26 | 1982-09-25 | 1983-03-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-03-26 | 1986-09-25 | 1987-03-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-03-26 | 1990-09-25 | 1991-03-27 | $7700.00 | Window Closed / Lapsed |