US3798661A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic diaphragm control device for a camera
Assignee: Canon Inc
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Filing: 1972-08-29
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Granted: 1974-03-19
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Expires: 1992-08-29
Abstract
Abstract In the device disclosed, a mechanism while it is changing the aperture value of a diaphragm from a starting value, also opens and closes switching means a number of times equal to the extent to which the diaphragm is being changed. Suitable circuit means accumulate signals corresponding to the number of times the switching means is closed. A comparator compares the resulting stored value of the accumulated signals with a reference voltage that corresponds to photographic information such as the output of a light measuring photoresistor. When the accumulated stored value reaches the measured reference voltage, stopping means stop the aperture reducing operation.
Inventors
- 👤 T Taguchi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 17:58
CPC Classifications
G; G03; G03B; G03B7/00; G03B7/08; G03B7/081; G03B7/085
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
214 words
An automatic diaphragm control device for a camera, comprising diaphragm control means for continuously changing the aperture of a diaphragm, stopping means coupleable to said diaphragm control means for stopping the aperture changing operation of the diaphragm control means, switching means responsive to said diaphragm control means for opening and closing repeatedly a number of times determined by the variation of the diaphragm value, storage means for storing and accumulating signals, signal generating means coupled to said switching means and said storage means for generating signals responsive to opening and closing of said switching means and for applying the signals intermittently to said storage means so that said storage means accumulates the signals and produces a stored value which varies stepwise corresponding to the variation of the aperture, reference generating means for generating a reference signal corresponding to a photographic value, comparator means coupled to said reference generating means and said storage means for comparing the value of the signal produced by said reference generating means and the signals stored in said storage means and for producing an output when the balance between the signals changes, and activating means coupled to said comparator means and said stopping means for activating the stopping means in response to changing of the balance in said comparator means.
Claim 2
Dependent Claim
214 words
An automatic diaphragm control device for a camera, comprising diaphragm control means for continuously changing the aperture of a diaphragm, stopping means coupleable to said diaphragm control means for stopping the aperture changing operation of the diaphragm control means, switching means responsive to said diaphragm control means for opening and closing repeatedly a number of times determined by the variation of the diaphragm value, storage means for storing and accumulating signals, signal generating means coupled to said switching means and said storage means for generating signals responsive to opening and closing of said switching means and for applying the signals intermittently to said storage means so that said storage means accumulates the signals and produces a stored value which varies stepwise corresponding to the variation of the aperture, reference generating means for generating a reference signal corresponding to a photographic value, comparator means coupled to said reference generating means and said storage means for comparing the value of the signal produced by said reference generating means and the signals stored in said storage means and for producing an output when the balance between the signals changes, and activating means coupled to said comparator means and said stopping means for activating the stopping means in response to changing of the balance in said comparator means.
Claim 3
Dependent Claim
44 words
A device as in claim 1, wherein said diaphragm control means includes a movable mechanical member and wherein said switching means includes a switchover contact coupled to said movable member and switching back and forth repeatedly in response to movement of said mechanical member.
Claim 4
Dependent Claim
60 words
A device as in claim 1, wherein said storage means includes a capacitor and wherein said signal generating means responds to opening and closing of said switching means by intermittently applying a voltage to said capacitor and preventing the voltage from leaking off and then applying the next voltage so that the voltage across the capacitor builds up in steps.
Claim 5
Dependent Claim
44 words
A device as in claim 3, wherein said diaphragm control means includes a movable mechanical member and wherein said switching means includes a switchover contact coupled to said movable member and switching back and forth repeatedly in response to movement of said mechanical member.
Claim 6
Dependent Claim
27 words
A device as in claim 3, wherein said signal generating means includes diode means for applying the signals to the capacitor and preventing them from leaking off.
Claim 7
Dependent Claim
56 words
A device as in claim 1, wHerein said switching means includes a first illuminating element and a light receiving element, and shielding means movable with said control means and also forming a part of said control means for intermittently shielding the light from the illuminating means according to the variation in the change of diaphragm value.
Claim 8
Dependent Claim
25 words
A device as in claim 6, wherein said control means includes a gear having teeth and said shielding means includes a part of said gear.
Claim 9
Dependent Claim
60 words
A device as in claim 6, wherein said storage means includes a capacitor and wherein said signal generating means responds to opening and closing of said switching means by intermittently applying a voltage to said capacitor and preventing the voltage from leaking off and then applying the next voltage so that the voltage across the capacitor builds up in steps.
Claim 10
Dependent Claim
44 words
A device as in claim 8, wherein said diaphragm control means includes a movable mechanical member and wherein said switching means includes a switchover contact coupled to said movable member and switching back and forth repeatedly in response to movement of said mechanical member.
References Cited (Backward Citations)
US3466447A
Cited
US3482497A
Cited
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 |