US3790847A - Arrangement provided with an electronic flash bulb - Google Patents

Arrangement provided with an electronic flash bulb Download PDF

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Publication number
US3790847A
US3790847A US00013373A US3790847DA US3790847A US 3790847 A US3790847 A US 3790847A US 00013373 A US00013373 A US 00013373A US 3790847D A US3790847D A US 3790847DA US 3790847 A US3790847 A US 3790847A
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US
United States
Prior art keywords
capacitor
flash
circuit
conduction device
conduction
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Expired - Lifetime
Application number
US00013373A
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English (en)
Inventor
H Hintz
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US Philips Corp
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US Philips Corp
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Filing date
Publication date
Application filed by US Philips Corp filed Critical US Philips Corp
Application granted granted Critical
Publication of US3790847A publication Critical patent/US3790847A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
    • H05B41/14—Circuit arrangements
    • H05B41/30—Circuit arrangements in which the lamp is fed by pulses, e.g. flash lamp
    • H05B41/32—Circuit arrangements in which the lamp is fed by pulses, e.g. flash lamp for single flash operation
    • H05B41/325—Circuit arrangements in which the lamp is fed by pulses, e.g. flash lamp for single flash operation by measuring the incident light

Definitions

  • ABSTRACT The invention relates to an arrangement provided with an electronic flash bulb which is fed from a main capacitor.
  • a so-c-alled quench tube is arranged across the bulb. This quench tube is ignited when sufficient light is emitted by the bulb.
  • drawback of the known arrangement is that the main capacitor is substantially discharged when this quench tube is ignited.
  • the invention provides a solution wherein the bulb is fed through a thyristor which :is extinguished after some time by a circuit including a second thyristor.
  • the advantage is that the main capacitor is now less discharged and the arrangement is thus sooner ready for the next flash.
  • the present invention relates to an improved my ristor switching for an electronic flash bulb, said arrangement including a photosensitve member and a supplycapacitor in which the duration of the flash of the flash bulb is influenced by the quantity of light which is reflected onto the photosensitive member by an object to be photographed.
  • the supply circuit of the flash bulb includes two parallel arranged thyristors each of which is connected to its own supply capacitor, the capacitances of these supply capacitors being unequal and one thyristor being rendered conducting at the instant an ignition pulse is applied to the flash bulb.
  • the other thyristor is subsequently rendered conducting by a control circuit including the photosensitive member.
  • the current supply to the flash bulb is not interrupted by the elimination of the charge on the capacitor, but rather by switching off the energy supply to the bulb.
  • An advantage of the present invention is, inter alia, that the current peaks occurring in the unit are comparatively low so that less stringent requirements need be imposed on the supply capacitor.
  • the drawing shows a circuit diagram of an arrange ment according to the invention.
  • a capacitor 3 is charged with the polarity indicated through a voltage inverter whereof only the transformer l is shown) and through a diode 2.
  • the capacitor also is connected through a thyristor 4 to a flash bulb 5.
  • a switch 6 By activating a switch 6 the flash bulb 5 and the thyristor 4 are both rendered conducting. The exposure then commences.
  • a control signal is generated in a control circuit which is provided, inter alia, with a photosensitive resistor 7 (facing the object to be photographed) and a current source not further shown.
  • This control signal is passed on through a transformer 8 to the electrodes of a thyristor 9.
  • the control circuit renders the thyristor 9 conducting when the object to be photographed has received a desired quantity of light.
  • the thyristor 9 is connected to a capacitor 10.
  • the capacitor W was previously charged with the polarity shown through a second winding 11 of the transformer 1 of the voltage inverter and through a diode 12.
  • the capacitor lll may alternatively be charged by a voltage doubler circuit if, for example, the transformer of the voltage inverter has only one secondary winding.
  • the thyristor 9 takes over the supply of current to the flash bulb 5 from the circuit that includes the thyristor 4. If the period during which current flows through the thyristor 9 is longer than the recovery time of the thyristor 4, which is approximately 10 20 tsec, then the thyristor 4 is blocked and the direct current supply to the flash bulb 5 from the capacitor 3 is interrupted.
  • the capacitance of the capacitor 10 is about 10 30 #F, so this may be much smaller than that of the capacitor 3, the characteristic value of which is approximately 500 [.LF. It is true that during the process of switching off, the energy stored in the capacitor 10 is applied to the flash bulb 5.
  • This energy first causes a given increase in the luminance of the flash, but this quantity of energy is relatively small and substantially constant so that it can be taken into account when calibrating the auxiliary arrangement including the photosensitive resistor.
  • the currents flowing through the thyristors 4 and 9 are not higher than the current flowing through the flash bulb.
  • An-electronic flash arrangement for an electronic flash bulb comprising, a photosensitive member arranged to respond to the flash bulb light reflected by an object to be photographed, a first supply capacitor, a second supply capacitor, a supply circuit for the flash bulb comprising first and second parallel arranged thyristors and means interconnecting said first and second thyristors with said first and second supply capacitors, respectively, and with the flash bulb, means serially connecting the second capacitor and the second thyristor in shunt with the first thyristor, the capacitance of said first capacitor being substantially larger than the capacitance of said second capacitor, means for coupling said first and second capacitors to a source of charge current so that the second capacitor is charged to a higher potential than the first capacitor, means for triggering the first thyristor into conduction at the instant an ignition pulse is applied to the flash bulb, and a control circuit including the photosensitive member for triggering the second thyristor into conduction after the first thyristor has been triggered whereby
  • a flash control circuit for a flash tube comprising, a first capacitor for supplying operating current to the flash tube, a first controlled conduction device connected in a first circuit with said first capacitor and said flash tube so as to control the discharge of said capacitor across the flash tube, a second capacitor having a different capacitance than the first capacitor, a second controlled conduction device connected in a second circuit with said first and second capacitors and said flash tube so as to control the discharge of the second capacitor across the flash tube and to apply the voltage on said second capacitor to the first conduction device via said second conduction device and in a sense to turn off said first conduction device, a control circuit coupled to said second conduction device and including a photosensitive element arranged to respond to the flash tube light reflected by an object, means for coupling said first and second capacitors to a source of charge current in a manner such that the second capacitor is charged to a voltage level that is independent of the tube ignition voltage, means for applying an ignition pulse to the flash tube, means for triggering said first conduction device into conduction in synchronism with
  • said conduction devices each comprise a controlled rectifier having a control electrode
  • said triggering means and said pulse applying means together comprising a transformer with a primary winding arranged to be selectively connected to a source of voltage and first and second secondary windings coupled to the control electrode of the first controlled rectifier and to a starter electrode of said flash tube, respectively, the control electrode of said second controlled rectifier being coupled to said control circuit which is arranged to trigger said second controlled rectifier into conduction at a point in time subsequent to when the first controlled rectifier and the flash tube are triggered into conduc tion and independently of the current then flowing through the flash tube.
  • a flash control circuit for a flash tube comprising, a pair of terminals, first and second capacitors, means connecting said first and second capacitors in series across said terminals, means coupled to said terminals for electrically charging said capacitors with the same polarity and in a manner such that the second capacitor is charged to a voltage level that can be chosen independently of the volage level to which the first capacitor is charged, first and second controlled conduction devices, first means connecting said first controlled conduction device in circuit with said first capacitor and said flash tube so as to control the discharge of said first capacitor across the flash tube, a second means connecting said second controlled conduction device in circuit with said second capacitor and said flash tube in a manner so as to apply a reverse bias voltage from said second capacitor to said first conduction device when said second conduction device is triggered into conduction, a control circuit coupled to a control electrode of said second conduction device and including a photosensitive element arranged to respond to the flash tube light reflected by an object, means for triggering the first conduction device into conduction to discharge the first capacitor and thereby flash said tube

Landscapes

  • Discharge-Lamp Control Circuits And Pulse- Feed Circuits (AREA)
  • Stroboscope Apparatuses (AREA)
  • Exposure Control For Cameras (AREA)
US00013373A 1969-03-01 1970-02-24 Arrangement provided with an electronic flash bulb Expired - Lifetime US3790847A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE19691910544 DE1910544B2 (de) 1969-03-01 1969-03-01 Elektronisches blitzlichtgeraet mit von der helligkeit des aufnahmeobjektes gesteuerter blitzroehrenentladung

Publications (1)

Publication Number Publication Date
US3790847A true US3790847A (en) 1974-02-05

Family

ID=5726853

Family Applications (1)

Application Number Title Priority Date Filing Date
US00013373A Expired - Lifetime US3790847A (en) 1969-03-01 1970-02-24 Arrangement provided with an electronic flash bulb

Country Status (7)

Country Link
US (1) US3790847A (ja)
JP (1) JPS4831621B1 (ja)
BE (1) BE746703A (ja)
DE (1) DE1910544B2 (ja)
FR (1) FR2033094A5 (ja)
GB (1) GB1292373A (ja)
NL (1) NL160142C (ja)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5979233A (ja) * 1982-10-28 1984-05-08 Canon Inc 閃光装置

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3238419A (en) * 1962-06-07 1966-03-01 Gen Electric Electrical protective circuit
US3376470A (en) * 1965-08-12 1968-04-02 Atomic Energy Commission Usa Capacitor discharge circuit for starting and sustaining a welding arc
US3497768A (en) * 1968-03-05 1970-02-24 Addressograph Multigraph One shot operation circuit for a gas discharge lamp
US3541387A (en) * 1968-04-23 1970-11-17 Bosch Elektronik Gmbh Control system for terminating the discharge of a flash lamp
US3591829A (en) * 1967-04-20 1971-07-06 Minolta Camera Kk Automatic control device for electronic flash

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3238419A (en) * 1962-06-07 1966-03-01 Gen Electric Electrical protective circuit
US3376470A (en) * 1965-08-12 1968-04-02 Atomic Energy Commission Usa Capacitor discharge circuit for starting and sustaining a welding arc
US3591829A (en) * 1967-04-20 1971-07-06 Minolta Camera Kk Automatic control device for electronic flash
US3497768A (en) * 1968-03-05 1970-02-24 Addressograph Multigraph One shot operation circuit for a gas discharge lamp
US3541387A (en) * 1968-04-23 1970-11-17 Bosch Elektronik Gmbh Control system for terminating the discharge of a flash lamp

Also Published As

Publication number Publication date
GB1292373A (en) 1972-10-11
DE1910544A1 (de) 1970-12-17
NL160142B (nl) 1979-04-17
DE1910544B2 (de) 1972-01-13
JPS4831621B1 (ja) 1973-10-01
FR2033094A5 (ja) 1970-11-27
BE746703A (fr) 1970-08-27
NL7002788A (ja) 1970-09-03
NL160142C (nl) 1979-09-17

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