US3798664A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrical shutter
Assignee: Minolta Co Ltd
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Filing: 1972-10-06
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Granted: 1974-03-19
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Expires: 1992-10-06
Abstract
Abstract A shutter control device has two delay circuits and a timing circuit including a photoconductive element for determining a delay period as a function of the intensity of the scene light. The timing circuit and one of the delay circuits are actuated simultaneously with the operation of the shutter release and the other delay circuit is operated when the first actuated delay circuit attains a given potential. The shutter closing is initiated when the potentials of the two delay circuits are equal.
Inventors
- 👤 M Matsuda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 20:35
CPC Classifications
G; G03; G03B; G03B7/00; G03B7/08; G03B7/081; G03B7/083
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
182 words
A shutter control device for a photographic camera having a shutter release mechanism, a shutter opening mechanism, a shutter closing mechanism and a photoconductive element normally exposed to scene light through an objective lens of the camera and unexposed to the light while said shutter mechanisms are operative, comprising: a first timer circuit and a second timer circuit for respectively storing first and second signals varying as the same function of time; a photomertric circuit including said photoconductive element for actuating said second timer circuit after a delay period determined as a function of the intensity of the scene light; said photometric circuit and said first timer circuit are actuated simultaneously by operation of said shutter release mechanism; a switch for deactuating said first timer circuit in response to actuation of said shutter opening mechanism for producing said first signal; means for actuating said shutter closing member; and a control circuit responsive to said first and second signals for energizing said means for actuating said shutter closing member at the instant when said first signal is substantially equal to said second signal.
Claim 2
Dependent Claim
182 words
A shutter control device for a photographic camera having a shutter release mechanism, a shutter opening mechanism, a shutter closing mechanism and a photoconductive element normally exposed to scene light through an objective lens of the camera and unexposed to the light while said shutter mechanisms are operative, comprising: a first timer circuit and a second timer circuit for respectively storing first and second signals varying as the same function of time; a photomertric circuit including said photoconductive element for actuating said second timer circuit after a delay period determined as a function of the intensity of the scene light; said photometric circuit and said first timer circuit are actuated simultaneously by operation of said shutter release mechanism; a switch for deactuating said first timer circuit in response to actuation of said shutter opening mechanism for producing said first signal; means for actuating said shutter closing member; and a control circuit responsive to said first and second signals for energizing said means for actuating said shutter closing member at the instant when said first signal is substantially equal to said second signal.
Claim 3
Dependent Claim
51 words
A shutter control device as in claim 1, wherein said shutter release mechanism comprises a manually operable release member movable to a first and a second position for actuating said photometric circuit and said first timer circuit in said first position and actuating said shutter opening member in said second position.
Claim 4
Dependent Claim
31 words
A shutter control device as in claim 2, further comprising a locking means for preventing said release member from actuating said shutter opening mechanism until said second timer circuit is actuated.
Claim 5
Dependent Claim
52 words
A shutter control device as in claim 3, wherein said locking means comprises: means for stopping said release member in said first position; means for releasing said means for stopping; And switching means connected to said photometric circuit for actuating said means for releasing after the delay period of said photometric circuit.
Claim 6
Dependent Claim
141 words
A shutter control device as in claim 1, further comprising a power source and wherein said photometric circuit includes a capacitance connected in series with said photoconductive element and a second switch connected to the junction between said photoconductive element and said capacitance, said second switch is responsive to a predetermined voltage stored by said capacitance; said second timer circuit is connected to said power source via said second switch; said control circuit includes a differential amplifier having two input terminals respectively connected to said first timer circuit and said second timer circuit; said first and second timer circuits each comprise a series connected resistance and capacitance and the respective resistance and capacitance of said first and second timer circuits are substantially equal; and said means for actuating said shutter closing member includes additional switching means triggered by said differential amplifier.
Claim 7
Dependent Claim
41 words
A shutter control device as in claim 5, further comprising an indicating member and a third switch connected to the junction between said photoconductive element and said capacitance for energizing said indicating member with said condenser charged to said predetermined voltage.
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) | 1977-03-18 | 1977-09-17 | 1978-03-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-18 | 1981-09-17 | 1982-03-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-18 | 1985-09-17 | 1986-03-19 | $7700.00 | Window Closed / Lapsed |