US3716753A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Arrangement including an electronic flash tube
Assignee: US Philips Corp
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Filing: 1970-11-03
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Granted: 1973-02-13
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Expires: 1990-11-03
Abstract
Abstract The invention relates to an arrangement including an electronic flash tube which is fed from a previously charged main capacitor. In a known arrangement a so-called quench tube is arranged across the flash tube. This quench tube is ignited when sufficient light energy is emitted by the flash tube. A drawback of the known arrangement is that the main capacitor becomes completely discharged when this quench tube is ignited. The invention provides a solution in which the shunt across the flash tube also includes a capacitor. The result of this simple step is that the main capacitor is not completely discharged. This has the advantage that the capacitor can be recharged rapidly again for taking the next flash photograph and that the device serving for the supply of this main capacitor is less rapidly exhausted.
Inventors
- 👤 E Exner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 21:16
CPC Classifications
H; H05; H05B; H05B41/00; H05B41/14; H05B41/30; H05B41/32; H05B41/325
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
130 words
A flash tube control circuit comprising, a supply capacitor connected across the flash tube, means for charging the capacitor to a given voltage, a controlled switching element, an auxiliary capacitor, means connecting said switching element in series circuit with said auxiliary capacitor in a shunt circuit across the flash tube, a photosensitive member arranged to respond to the flash tube light reflected by an object exposed thereto, and a control circuit including said photosensitive member coupled to a control electrode of the switching element in a manner such that the triggering of the switching element and hence the flash duration is controlled as a function of the brightness of the exposed object, said shunt circuit being arranged to prevent the complete discharge of the supply capacitor during a flash cycle.
Claim 2
Dependent Claim
130 words
A flash tube control circuit comprising, a supply capacitor connected across the flash tube, means for charging the capacitor to a given voltage, a controlled switching element, an auxiliary capacitor, means connecting said switching element in series circuit with said auxiliary capacitor in a shunt circuit across the flash tube, a photosensitive member arranged to respond to the flash tube light reflected by an object exposed thereto, and a control circuit including said photosensitive member coupled to a control electrode of the switching element in a manner such that the triggering of the switching element and hence the flash duration is controlled as a function of the brightness of the exposed object, said shunt circuit being arranged to prevent the complete discharge of the supply capacitor during a flash cycle.
Claim 3
Dependent Claim
130 words
A flash tube control circuit comprising, a supply capacitor connected across the flash tube, means for charging the capacitor to a given voltage, a controlled switching element, an auxiliary capacitor, means connecting said switching element in series circuit with said auxiliary capacitor in a shunt circuit across the flash tube, a photosensitive member arranged to respond to the flash tube light reflected by an object exposed thereto, and a control circuit including said photosensitive member coupled to a control electrode of the switching element in a manner such that the triggering of the switching element and hence the flash duration is controlled as a function of the brightness of the exposed object, said shunt circuit being arranged to prevent the complete discharge of the supply capacitor during a flash cycle.
Claim 4
Dependent Claim
130 words
A flash tube control circuit comprising, a supply capacitor connected across the flash tube, means for charging the capacitor to a given voltage, a controlled switching element, an auxiliary capacitor, means connecting said switching element in series circuit with said auxiliary capacitor in a shunt circuit across the flash tube, a photosensitive member arranged to respond to the flash tube light reflected by an object exposed thereto, and a control circuit including said photosensitive member coupled to a control electrode of the switching element in a manner such that the triggering of the switching element and hence the flash duration is controlled as a function of the brightness of the exposed object, said shunt circuit being arranged to prevent the complete discharge of the supply capacitor during a flash cycle.
Claim 5
Dependent Claim
93 words
A control circuit as claimed in claim 1 wherein the switching element comprises a thyristor and the shunt circuit also includes a resistor, a diode, means connecting the diode in shunt circuit with the thyristor with the diode pass direction opposite to that of the thyristor, said capacitors being chosen so that C1/C1 + C2 times the given voltage of the supply capacitor is larger than the minimum operating voltage of the flash tube in which: C1 is the capacitance of the supply capacitor and C2 is the capacitance of the auxiliary capacitor.
Claim 6
Dependent Claim
44 words
A control circuit as claimed in claim 1 wherein said switching element comprises a thyristor, said circuit further comprising a diode connected across said thyristor with opposite polarity so as to provide a discharge path for said auxiliary capacitor that includes the flash tube.
Claim 7
Dependent Claim
41 words
A control circuit as claimed in claim 3 further comprising a resistor connected in series with said thyristor and said auxiliary capacitor across the flash tube and in series with said diode and flash tube in the auxiliary capacitor discharge path.
Claim 8
Dependent Claim
33 words
A control circuit as claimed in claim 1 wherein said control circuit includes means responsive to the flow of current in the flash tube to derive a control signal for said switching element.
Claim 9
Dependent Claim
102 words
A control circuit as claimed in claim 1 wherein said shunt circuit further comprises a resistor connected in series with the switching element and the auxiliary capacitor in the order named, a diode connected in parallel with the switching element with opposite polarity, a second resistor connected across said auxiliary capacitor, means for applying a trigger voltage to a control electrode of the flash tube and wherein said control circuit further comprises a transformer with a primary winding in series with the flash tube and a secondary winding coupled to the photosensitive member and to the control electrode of the switching element.
Claim 10
Dependent Claim
53 words
A control circuit as claimed in claim 3 wherein the capacitors are chosen so that C1/C1 + C2 times the given voltage of the supply capacitor exceeds the minimum operating voltage of the flash tube wherein: C1 is the capacitance of the supply capacitor and C2 is the capacitance of the auxiliary capacitor.
Claim 11
Dependent Claim
14 words
A control circuit as claimed in claim 2 wherein C1 is equal to C2.
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) | 1976-02-13 | 1976-08-14 | 1977-02-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-02-13 | 1980-08-14 | 1981-02-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-02-13 | 1984-08-14 | 1985-02-13 | $7700.00 | Window Closed / Lapsed |