US3696268A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Arrangement including an electronic flash tube
Assignee: US Philips Corp
•
Filing: 1970-11-03
•
Granted: 1972-10-03
•
Expires: 1990-11-03
Abstract
Abstract The invention relates to an arrangement including an electronic flash tube and a controlled semiconductor rectifier for extinguishing this tube. In order to extinguish the flash tube in a known arrangement, it is shunted by a semiconductor rectifier producing a short circuit across the tube. A drawback thereof is that the supply source of the arrangement a needlessly and heavily loaded thereby. In an arrangement according to the invention an auxiliary capacitor is used which receives a voltage larger than the supply voltage of the arrangement. When the instant of extinguishing has come the voltage of this auxiliary capacitor used to extinguish a further controlled rectifier arranged in series with the tube. Consequently, the supply source of an arrangement according to the invention is much less heavily loaded and in addition the arrangement is sooner ready for the next flash.
Inventors
- 👤 Emil August Exner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 20:12
CPC Classifications
H; H05; H05B; H05B41/00; H05B41/14; H05B41/30; H05B41/32; H05B41/325
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
258 words
An ignition control circuit for an electronic flash tube comprising, first and second input terminals adapted to be connected to a source of DC voltage, first and second semiconductor controlled rectifiers, means serially connecting said first controlled rectifier and the flash tube to said first and second input terminals, at least one chargeable element and a further circuit impedance element serially connected in shunt with said flash tube prior to the tube flash, said further circuit element exhibiting a high impedance at least during the flash period of the tube, means connecting the second controlled rectifier between the first input terminal and the junction of the chargeable element and the further circuit element, a control circuit including a photosensitive member coupled to the control electrode of said second controlled rectifier, said photosensitive member being arranged to respond to the flash tube light reflected thereto by an object exposed to the tube flash such that the second controlled rectifier is triggered into conduction as a function of the brightness of said object thereby to extinguish the flash tube and thus limit the flash duration as a function of the object brightness, and means for applying an electric charge to said chargeable element of a polarity opposed to that of the input terminals and of a magnitude that is larger than the voltage at the input terminals at a moment after the flash tube is ignited whereby the voltage of the chargeable element is capable of extinguishing the first controlled rectifier when the second controlled rectifier is triggered into conduction.
Claim 2
Dependent Claim
258 words
An ignition control circuit for an electronic flash tube comprising, first and second input terminals adapted to be connected to a source of DC voltage, first and second semiconductor controlled rectifiers, means serially connecting said first controlled rectifier and the flash tube to said first and second input terminals, at least one chargeable element and a further circuit impedance element serially connected in shunt with said flash tube prior to the tube flash, said further circuit element exhibiting a high impedance at least during the flash period of the tube, means connecting the second controlled rectifier between the first input terminal and the junction of the chargeable element and the further circuit element, a control circuit including a photosensitive member coupled to the control electrode of said second controlled rectifier, said photosensitive member being arranged to respond to the flash tube light reflected thereto by an object exposed to the tube flash such that the second controlled rectifier is triggered into conduction as a function of the brightness of said object thereby to extinguish the flash tube and thus limit the flash duration as a function of the object brightness, and means for applying an electric charge to said chargeable element of a polarity opposed to that of the input terminals and of a magnitude that is larger than the voltage at the input terminals at a moment after the flash tube is ignited whereby the voltage of the chargeable element is capable of extinguishing the first controlled rectifier when the second controlled rectifier is triggered into conduction.
Claim 3
Dependent Claim
72 words
An ignition circuit as claimed in claim 1 further comprising a main capacitor connected across the input terminals and directly charged by the DC voltage applied thereto, and wherein the chargeable element comprises an auxiliary capacitor and said charge applying means comprises a series arrangement of a diode and a resistor connected between the first input terminal and the side of the auxiliary capacitor that is remote from said further circuit element.
Claim 4
Dependent Claim
21 words
An ignition circuit as claimed in claim 1 wherein the further circuit element comprises a resistor in series with a diode.
Claim 5
Dependent Claim
52 words
An ignition circuit as claimed in claim 1 wherein the further circuit element comprises a switch which is coupled to the shutter mechanism of a photocamera in a manner such that said switch is closed in the closed condition of the shutter and is open in the open condition of the shutter.
Claim 6
Dependent Claim
203 words
An ignition control circuit for a flash discharge tube comprising, a pair of input terminals adapted to be connected to a source of DC voltage, a supply capacitor connected across said input terminals so as to be charged to a given ignition voltage, a first controlled switching element connected in series with the flash tube across said input terminals, an auxiliary capacitor, impedance means, means connecting the auxiliary capacitor and the impedance means in a series circuit across the terminals of the flash tube, a second controlled switching element connected in series with said impedance means across the input terminals, a photosensitive member arranged to respond to the flash tube light reflected thereto by an exposed object, a control circuit including said photosensitive member coupled to a control electrode of the second switching element to trigger same into conduction at a time determined by the brightness of the exposed object thereby to extinguish the flash tube, and means for triggering said first switching element into conduction thereby to at least partially discharge the supply capacitor across the flash tube, said auxiliary capacitor being coupled to said first switching element to bias same into cut-off in response to conduction in the second switching element.
Claim 7
Dependent Claim
203 words
An ignition control circuit for a flash discharge tube comprising, a pair of input terminals adapted to be connected to a source of DC voltage, a supply capacitor connected across said input terminals so as to be charged to a given ignition voltage, a first controlled switching element connected in series with the flash tube across said input terminals, an auxiliary capacitor, impedance means, means connecting the auxiliary capacitor and the impedance means in a series circuit across the terminals of the flash tube, a second controlled switching element connected in series with said impedance means across the input terminals, a photosensitive member arranged to respond to the flash tube light reflected thereto by an exposed object, a control circuit including said photosensitive member coupled to a control electrode of the second switching element to trigger same into conduction at a time determined by the brightness of the exposed object thereby to extinguish the flash tube, and means for triggering said first switching element into conduction thereby to at least partially discharge the supply capacitor across the flash tube, said auxiliary capacitor being coupled to said first switching element to bias same into cut-off in response to conduction in the second switching element.
Claim 8
Dependent Claim
50 words
An ignition circuit as claimed in claim 5 further comprising a charge circuit coupling the auxiliary capacitor to the input terminals so that the auxiliary capacitor is charged up independently of said first controlled switching element and with a polarity opposed to that of the voltage on the supply capacitor.
Claim 9
Dependent Claim
32 words
An ignition circuit as claimed in claim 6 wherein said second switching element comprises a thyristor and said impedance means comprises a first diode connected with the same polarity as the thyristor.
Claim 10
Dependent Claim
41 words
An ignition circuit as claimed in claim 7 wherein said charge circuit comprises a second diode connected in series with said auxiliary capacitor and said first diode across the input terminals and poled with the same polarity as the first diode.
Claim 11
Dependent Claim
34 words
An ignition circuit as claimed in claim 6 wherein said flash tube includes a trigger electrode and means for applying a trigger voltage thereto in synchronism with the triggering of said first switching element.
Claim 12
Dependent Claim
31 words
An ignition circuit as claimed in claim 5 wherein said impedance means comprises a diode poled so as to prevent the discharge of said auxiliary capacitor across the flash discharge tube.
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) | 1975-10-03 | 1976-04-03 | 1976-10-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-03 | 1980-04-03 | 1980-10-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-03 | 1984-04-03 | 1984-10-03 | $7700.00 | Window Closed / Lapsed |