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US4200375A Expired / Lapsed US ⏱️ 0.0 years remaining

Exposure controlling circuit for electric shutter

Assignee: Nidec Precision Corp
•
Filing: 1978-10-13
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Granted: 1980-04-29
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Expires: 1998-10-13
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Abstract

Abstract An exposure controlling circuit for electric shutters comprising a timer circuit which can determine a proper exposure time in response to the brightness of an object to be photographed and another time circuit which can determine the specific shortest exposure time in order to regulate the exposure time to be determined by the brightness of the object to be photographed to be less than the shortest exposure time obtainable by the inherent performance of the shutter mechanism to be used, whereby when the states of the above mentioned two time circuit started to act simultaneously in relation to the shutter release operation are reversed to each other, the shutter is closed. The above mentioned specific shortest exposure time can be selected.

Inventors

  • 👤 Yasuo Ishiguro
  • 👤 Kenji Wakazono
  • 👤 Toshihisa Saito

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-10-28 23:33
CPC Classifications
G; G03; G03B; G03B7/00; G03B7/08; G03B7/081; G03B7/083

Claims Analysis

Total Claims: 3
Claim 1
Independent Claim 98 words
An exposure controlling circuit for electric shutters comprising a first time circuit which can determine a proper exposure time in response to the brightness of an object to be photographed, and a second time circuit which is connected with said first time circuit and can determine the shortest exposure time, said first and second time circuits being arranged so as to be able to start their operations simultaneously as associated with the opening of the shutter and being arranged so that the shutter can only be closed when both states of said first and second time circuits reverse.
Claim 2
Dependent Claim 98 words
An exposure controlling circuit for electric shutters comprising a first time circuit which can determine a proper exposure time in response to the brightness of an object to be photographed, and a second time circuit which is connected with said first time circuit and can determine the shortest exposure time, said first and second time circuits being arranged so as to be able to start their operations simultaneously as associated with the opening of the shutter and being arranged so that the shutter can only be closed when both states of said first and second time circuits reverse.
Claim 3
Dependent Claim 32 words
An exposure controlling circuit for electric shutters according to claim 1, wherein said second time circuit is so arranged that the shortest exposure time to be determined by it can be selected.

References Cited (Backward Citations)

US3500729A Cited
US3798664A Cited
US3914776A Cited
US3641902A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1983-04-29 1983-10-29 1984-04-29 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1987-04-29 1987-10-29 1988-04-29 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1991-04-29 1991-10-29 1992-04-29 $7700.00 Window Closed / Lapsed

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