Patent US6272292B1 successfully refreshed from Google Patents.
US6272292B1
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Electronic flash control apparatus
Assignee: Nikon Corp
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Filing: 1999-12-22
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Granted: 2001-08-07
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Expires: 2019-12-22
Abstract
Abstract An electronic flash unit is caused to perform a pre-flash immediately before a photographing operation, and the quantity of light reflected by the subject during the pre-flash is measured by a flash metering unit. Based upon the output from the flash metering unit, a decision is made as to whether or not another pre-flash is to be implemented. Based upon the results of the decision-making, another pre-flash is performed if necessary. Thus, if the quantity of light measured by the flash metering unit during the pre-flash is too small or too large and a sufficient degree of accuracy is not achieved in the measurement, another pre-flash is performed to assure a high degree of accuracy in metering.
Inventors
- 👤 Hiroyuki Iwasaki
- 👤 Keiji Osawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 12:43
CPC Classifications
G; G03; G03B; G03B7/00; G03B7/16; G03B15/00; G03B15/02; G03B15/03; G03B15/05
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
106 words
An electronic flash control apparatus comprising: a flash metering unit that measures a light quantity of light reflected by a subject during a pre-flash performed immediately before a photographing operation; a decision-making unit that makes a decision as to whether or not another pre-flash is to be implemented based upon a signal output by said flash metering unit; a flash control unit that causes another pre-flash to be implemented based upon results of a decision made at said decision-making unit; and a flash output calculation unit that calculates an electronic flash output for the photographing operation based upon a signal output by said flash metering unit.
Claim 2
Dependent Claim
106 words
An electronic flash control apparatus comprising: a flash metering unit that measures a light quantity of light reflected by a subject during a pre-flash performed immediately before a photographing operation; a decision-making unit that makes a decision as to whether or not another pre-flash is to be implemented based upon a signal output by said flash metering unit; a flash control unit that causes another pre-flash to be implemented based upon results of a decision made at said decision-making unit; and a flash output calculation unit that calculates an electronic flash output for the photographing operation based upon a signal output by said flash metering unit.
Claim 3
Dependent Claim
36 words
An electronic flash control apparatus according to claim 1 , further comprising: an electronic flash unit that performs a flash at a flash output corresponding to results of calculation performed by said flash output calculation unit.
Claim 4
Dependent Claim
54 words
An electronic flash control apparatus according to claim 1 , wherein: said flash metering unit includes a photo-current storage portion that stores a photo-current generated by receiving light, and said flash metering unit performs a new storage after discharging an electrical charge stored during a first pre-flash when another pre-flash is to be implemented.
Claim 5
Dependent Claim
55 words
An electronic flash control apparatus according to claim 1 , wherein: said flash metering unit includes a photo-current storage portion that stores a photo-current generated by receiving light, and said flash metering unit performs a new storage by leaving an electrical charge stored during a first pre-flash undischarged when another pre-flash is to be implemented.
Claim 6
Dependent Claim
33 words
An electronic flash control apparatus according to claim 1 , wherein: when another pre-flash is to be performed, said flash metering unit changes a gain used to amplify photo-current generated by receiving light.
Claim 7
Dependent Claim
35 words
An electronic flash control apparatus according to claim 1 , wherein: said flash metering unit meters ambient light once after said pre-flash is completed regardless of the number of times said pre-flash has been performed.
Claim 8
Dependent Claim
43 words
An electronic flash control apparatus according to claim 1 , wherein: said flash control unit sets an upper limit to a total light quantity of flash light emitted by said electronic flash unit when a pre-flash is performed by said electronic flash unit.
Claim 9
Dependent Claim
93 words
An electronic flash control apparatus according to claim 1 , wherein: said flash metering unit is capable of performing metering for individual areas within a photographic field achieved by dividing the photographic field into a plurality of areas; and said flash output calculation unit selects a set of signals among a plurality of sets of signals obtained as outputs from said flash metering unit resulting from a plurality of pre-flashes that achieves a higher degree of metering accuracy and calculates a flash output for the photographing operation based upon the signals thus selected.
Claim 10
Dependent Claim
138 words
An electronic flash control apparatus comprising: a flash metering unit that measures a light quantity of light reflected by a subject during a pre-flash performed immediately before a photographing operation; a gain setting unit that sets a gain to be used to amplify a signal obtained from said flash metering unit metering the quantity of reflected light; a flash control unit that outputs a plurality of pre-flash commands to an electronic flash unit immediately before the photographing operation; a gain resetting unit that changes the gain set by said gain setting unit when a plurality of pre-flashes are implemented in response to said plurality of pre-flash commands output by said flash control unit; and a flash output calculation unit that calculates a flash output for the photographing operation based upon a signal output by said flash metering unit.
Claim 11
Dependent Claim
138 words
An electronic flash control apparatus comprising: a flash metering unit that measures a light quantity of light reflected by a subject during a pre-flash performed immediately before a photographing operation; a gain setting unit that sets a gain to be used to amplify a signal obtained from said flash metering unit metering the quantity of reflected light; a flash control unit that outputs a plurality of pre-flash commands to an electronic flash unit immediately before the photographing operation; a gain resetting unit that changes the gain set by said gain setting unit when a plurality of pre-flashes are implemented in response to said plurality of pre-flash commands output by said flash control unit; and a flash output calculation unit that calculates a flash output for the photographing operation based upon a signal output by said flash metering unit.
Claim 12
Dependent Claim
35 words
An electronic flash control apparatus according to claim 9 , further comprising: an electronic flash unit that performs a flash operation at a flash output corresponding to an output from said flash output calculation unit.
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) | 2004-08-06 | 2005-02-05 | 2005-08-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2008-08-06 | 2009-02-05 | 2009-08-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2012-08-06 | 2013-02-05 | 2013-08-07 | $7700.00 | Window Closed / Lapsed |