US4306281A
Expired / Lapsed
US
⏱️ 0.0 years remaining
DC-DC Converter for electronic flash unit
Assignee: Canon Inc
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Filing: 1980-10-03
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Granted: 1981-12-15
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Expires: 2000-10-03
Abstract
Abstract In a DC-DC converter for an electronic flash unit disclosed, an npn transistor is used as an oscillating transistor. The emitter of the npn transistor is connected to a main capacitor of the flash unit at least through a secondary winding of the converter. A diode is connected between the secondary winding and the main capacitor in such a manner that the emitter current of the npn transistor can flow into the main capacitor as an charging current through the secondary winding.
Inventors
- 👤 Tadashi Okino
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 22:49
CPC Classifications
H; H05; H05B; H05B41/00; H05B41/14; H05B41/30; H05B41/32; H02; H02M; H02M3/00; H02M3/22; H02M3/24; H02M3/28; H02M3/325; H02M3/335; H02M3/33507; H02M3/338; H02M3/3381
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
101 words
A DC-DC converter for an electronic flash unit having a main capacitor, said DC-DC converter comprising: (a) an oscillating transformer having a primary winding, a secondary winding and a feedback winding; (b) an npn oscillating transistor having an emitter connected to one electrode of said main capacitor through the secondary winding of said transformer, said transistor being arranged to apply a current for charging the main capacitor therewith; and (c) rectifying means which is arranged in a forward direction for said charging current and is connected between said one electrode of the main capacitor and the secondary winding of said transformer.
Claim 2
Dependent Claim
101 words
A DC-DC converter for an electronic flash unit having a main capacitor, said DC-DC converter comprising: (a) an oscillating transformer having a primary winding, a secondary winding and a feedback winding; (b) an npn oscillating transistor having an emitter connected to one electrode of said main capacitor through the secondary winding of said transformer, said transistor being arranged to apply a current for charging the main capacitor therewith; and (c) rectifying means which is arranged in a forward direction for said charging current and is connected between said one electrode of the main capacitor and the secondary winding of said transformer.
Claim 3
Dependent Claim
24 words
A DC-DC converter according to claim 1, wherein said npn oscillating transistor includes a base connected to the other electrode of said main capacitor.
Claim 4
Dependent Claim
23 words
A DC-DC converter according to claim 2, wherein said npn oscillating transistor includes a collector connected to the primary winding of said transformer.
Claim 5
Dependent Claim
38 words
A DC-DC converter according to claim 3, further comprising: a battery connected to the base of said npn oscillating transistor through the feedback winding of said transformer for applying a base current to the base of said transistor.
Claim 6
Dependent Claim
26 words
A DC-DC converter according to claim 4, wherein said rectifying means includes a diode having an anode thereof connected to the secondary winding of said transformer.
Claim 7
Dependent Claim
28 words
A DC-DC converter according to claim 5, wherein said battery includes a positive electrode connected to the anode of said diode through the secondary winding of said transformer.
Claim 8
Dependent Claim
33 words
A DC-DC converter according to claim 2, further comprising: a diode having an anode thereof connected to the emitter of said transistor and a cathode thereof connected to the base of said transistor.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-12-14 | 1985-06-15 | 1985-12-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-12-14 | 1989-06-15 | 1989-12-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-12-14 | 1993-06-15 | 1993-12-15 | $7700.00 | Window Closed / Lapsed |