US4486086A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electronic flash apparatus
Assignee: Eastman Kodak Co
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Filing: 1983-11-23
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Granted: 1984-12-04
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Expires: 2003-11-23
Abstract
Abstract Electronic flash apparatus produces a variable amount of flash illumination corresponding to pre-flash photographic conditions, i.e. subject distance, film speed, ambient light intensity, etc. Circuitry, which has a threshold adjustable in response to a pre-flash signal relating to the flash illumination required for the photographic conditions, monitors energy as it is delivered to a flash tube to produce flash illumination, for activating quenching circuitry to limit the discharging of a flash capacitor to an amount of energy corresponding to the pre-flash signal.
Inventors
- 👤 John M. Kresock
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 02:47
CPC Classifications
G; G03; G03B; G03B15/00; G03B15/02; G03B15/03; G03B15/05; G03B2215/00; G03B2215/05
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
161 words
In electronic flash apparatus for producing flash illumination corresponding to an anticipated photographic exposure operation, said flash apparatus including a flash tube, an energy-storage capacitor connected to deliver electrical energy to said flash tube to produce flash illumination, photographic condition indicating means settable in accordance with the anticipated photographic exposure operation and having an output corresponding to an amount of flash illumination that is desired for the exposure operation, and quenching means for terminating the delivery of energy to said flash tube, said flash apparatus further including: (a) energy-monitoring means for monitoring energy as said capacitor delivers it to said flash tube; and (b) threshold establishing means, operably associated with said energy-monitoring means and adjustable in response to said indicating means output, for causing activation of said quenching means to terminate the delivery of energy to said flash tube when the amount of energy delivered to said flash tube corresponds to the flash illumination to which said indicating means output corresponds.
Claim 2
Dependent Claim
161 words
In electronic flash apparatus for producing flash illumination corresponding to an anticipated photographic exposure operation, said flash apparatus including a flash tube, an energy-storage capacitor connected to deliver electrical energy to said flash tube to produce flash illumination, photographic condition indicating means settable in accordance with the anticipated photographic exposure operation and having an output corresponding to an amount of flash illumination that is desired for the exposure operation, and quenching means for terminating the delivery of energy to said flash tube, said flash apparatus further including: (a) energy-monitoring means for monitoring energy as said capacitor delivers it to said flash tube; and (b) threshold establishing means, operably associated with said energy-monitoring means and adjustable in response to said indicating means output, for causing activation of said quenching means to terminate the delivery of energy to said flash tube when the amount of energy delivered to said flash tube corresponds to the flash illumination to which said indicating means output corresponds.
Claim 3
Dependent Claim
33 words
Flash apparatus as defined in claim 1 further including an electronic switch serially connected with said flash tube and, responsive to said quenching means, for interrupting the discharging of energy from said capacitor.
Claim 4
Dependent Claim
104 words
Flash apparatus as defined in claim 1 wherein said energy-monitoring means includes: (a) first circuit means, connected to said capacitor, for producing a substantially constant signal corresponding to the energy stored by said capacitor at the initiating of the delivery of energy to said flash tube; (b) second circuit means for producing a time-varying signal corresponding to the energy stored by said capacitor during the delivery of energy to said flash tube; and (c) subtracting circuit means, connected to said first and second circuit means, for determining the difference between the constant and time-varying signals, thereby measuring the energy delivered to said flash tube.
Claim 5
Dependent Claim
40 words
Flash apparatus as defined in claim 3 wherein said threshold establishing means includes a comparator circuit having a first input responsive to the difference between the constant and time-varying signals and a second input responsive to said indicating means output.
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) | 1987-12-04 | 1988-06-04 | 1988-12-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-12-04 | 1992-06-04 | 1992-12-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-12-04 | 1996-06-04 | 1996-12-04 | $7700.00 | Window Closed / Lapsed |