Patent US3673415A successfully refreshed from Google Patents.
US3673415A
Expired / Lapsed
US
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Shutter operating circuit having means to close shutter when light is insufficient
Assignee: Yashica Co Ltd
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Filing: 1970-11-04
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Granted: 1972-06-27
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Expires: 1990-11-04
Abstract
Abstract In a shutter operating circuit comprising a shutter time determining circuit including a photo-electromotive element, and a high input impedance transistor; means to initiate the operation of the shutter time determining circuit; a shutter control circuit controlled by the shutter time determining circuit; and a source of supply connected to said two circuits, there are provided a series circuit connected across the source and including serially connected resistor and capacitor, and a switching transistor with its base electrode connected to the juncture between the resistor and the capacitor, the series circuit acting to trigger the switching transistor to operate the shutter control circuit when the shutter time determining circuit fails to operate after elapse of a predetermined interval after the operation of the initiating means.
Inventors
- 👤 Hirofumi Yoshimura
- 👤 Hisatoshi Takahata
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 13:57
CPC Classifications
G; G03; G03B; G03B7/00; G03B7/08; G03B7/081; G03B7/083
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
127 words
In a shutter operating circuit comprising a shutter time determining circuit including a photo-electromotive element and a high input impedance transistor; means to initiate the operation of said shutter time determining circuit; a shutter control circuit controlled by said shutter time determining circuit; and a source of supply connected to said two circuits, the improvement which comprises a series circuit connected across said source and including serially connected a first resistor and capacitor and a switching transistor with its base electrode connected to the juncture between said resistor and capacitor, said series circuit acting to trigger said switching transistor to operate said shutter control circuit when said shutter time determining circuit fails to operate after elapse of a predetermined interval after the operation of said initiating means.
Claim 2
Dependent Claim
127 words
In a shutter operating circuit comprising a shutter time determining circuit including a photo-electromotive element and a high input impedance transistor; means to initiate the operation of said shutter time determining circuit; a shutter control circuit controlled by said shutter time determining circuit; and a source of supply connected to said two circuits, the improvement which comprises a series circuit connected across said source and including serially connected a first resistor and capacitor and a switching transistor with its base electrode connected to the juncture between said resistor and capacitor, said series circuit acting to trigger said switching transistor to operate said shutter control circuit when said shutter time determining circuit fails to operate after elapse of a predetermined interval after the operation of said initiating means.
Claim 3
Dependent Claim
64 words
The shutter operating circuit according to claim 1 wherein said photo-electromotive circuit is connected in series with a capacitor which is normally short circuit by a switch which is opened when a shutter release is operated so that when an object to be photographed has sufficient light, said photo-electromotive element charges said capacitor within a predetermined interval to trigger said high input impedance transistor.
Claim 4
Dependent Claim
16 words
The shutter operating circuit according to claim 1 wherein said first resistor is a variable resistor.
Claim 5
Dependent Claim
39 words
The shutter operating circuit according to claim 1 is further provided with the second resistor connectable across said first resistor of said series circuit and a switch adapted to connect said second resistor in parallel with said first resistor.
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) | 1975-06-27 | 1975-12-27 | 1976-06-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-06-27 | 1979-12-27 | 1980-06-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-06-27 | 1983-12-27 | 1984-06-27 | $7700.00 | Window Closed / Lapsed |