US4396870A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electronic flash device
Assignee: West Electric Co Ltd
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Filing: 1981-06-24
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Granted: 1983-08-02
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Expires: 2001-06-24
Abstract
Abstract An electronic flash device provided with an auxiliary winding electromagnetically coupled to a winding in a DC-DC converter which is connected to a main power supply and generates a voltage for charging a main flash capacitor, an auxiliary capacitor adapted to be charged with at least the voltage induced across the auxiliary winding, and a control circuit for maintaining the voltage charged across the auxiliary capacitor at a predetermined level, whereby the voltage charged across the auxiliary capacitor can be delivered to integrated circuits for the flash device.
Inventors
- 👤 Takahiro Ikeda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 12:39
CPC Classifications
H; H05; H05B; H05B41/00; H05B41/14; H05B41/30; H05B41/32
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
134 words
An electronic flash device of the type in which an auxiliary winding is electromagnetically coupled to a winding in a DC-DC converter for charging a main flash capacitor and an auxiliary capacitor is charged with the voltage induced across said auxiliary winding through a diode so that the voltage across said auxiliary capacitor can be used as an auxiliary power supply, characterized by the provision of a voltage control circuit comprising a voltage detector for detecting the voltage across said auxiliary capacitor, and a control circuit which is connected in series to said auxiliary winding and which is adapted to decouple of said auxiliary winding from said winding in said DC-DC converter in response to the output signal from said voltage detector, whereby the voltage across said auxiliary capacitor can be controlled as desired.
Claim 2
Dependent Claim
134 words
An electronic flash device of the type in which an auxiliary winding is electromagnetically coupled to a winding in a DC-DC converter for charging a main flash capacitor and an auxiliary capacitor is charged with the voltage induced across said auxiliary winding through a diode so that the voltage across said auxiliary capacitor can be used as an auxiliary power supply, characterized by the provision of a voltage control circuit comprising a voltage detector for detecting the voltage across said auxiliary capacitor, and a control circuit which is connected in series to said auxiliary winding and which is adapted to decouple of said auxiliary winding from said winding in said DC-DC converter in response to the output signal from said voltage detector, whereby the voltage across said auxiliary capacitor can be controlled as desired.
Claim 3
Dependent Claim
44 words
An electronic flash device as set forth in claim 1 further characterized in that said auxiliary capacitor is connected through a second diode to said DC-DC converter so that said auxiliary capacitor can be also charged with a voltage generated in said DC-DC converter.
Claim 4
Dependent Claim
51 words
An electronic flash device as set forth in claim 1 or 2 further characterized in that said auxiliary capacitor is connected through a third diode to a main power supply for said DC-DC converter so that said auxiliary capacitor can be also charged with a voltage of said main power supply.
Claim 5
Dependent Claim
65 words
An electronic flash device as set forth in claim 1 further characterized in that said voltage detector comprises a first transistor adapted to detect the voltage being charged across said auxiliary capacitor in terms of a voltage across a resistor connected in parallel with said auxiliary capacitor, and a second transistor which is controlled by said first transistor so as to control said control circuit.
Claim 6
Dependent Claim
21 words
An electronic flash device as set forth in claim 1 further characterized in that said voltage detector includes a constant-voltage regulator.
Claim 7
Dependent Claim
20 words
An electronic flash device as set forth in claim 1 further characterized in that said control circuit includes a transistor.
Claim 8
Dependent Claim
27 words
An electronic flash device as set forth in claim 1 further characterized in that said auxiliary power supply is used for supplying power to one more ICs.
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) | 1986-08-01 | 1987-01-31 | 1987-08-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-08-01 | 1991-01-31 | 1991-08-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-08-01 | 1995-01-31 | 1995-08-02 | $7700.00 | Window Closed / Lapsed |