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US3716753A - Arrangement including an electronic flash tube - Google Patents

Arrangement including an electronic flash tube Download PDF

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Publication number
US3716753A
US3716753A US00086516A US3716753DA US3716753A US 3716753 A US3716753 A US 3716753A US 00086516 A US00086516 A US 00086516A US 3716753D A US3716753D A US 3716753DA US 3716753 A US3716753 A US 3716753A
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US
United States
Prior art keywords
capacitor
flash tube
switching element
control circuit
flash
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US00086516A
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English (en)
Inventor
E Exner
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
US Philips Corp
Original Assignee
US Philips Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by US Philips Corp filed Critical US Philips Corp
Application granted granted Critical
Publication of US3716753A publication Critical patent/US3716753A/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

  • This invention relates to an arrangement including an electronic flash tube which is ignited from a previously charged main capacitor and in which a supply branch including said tube is shunted by a circuit provided with at least a controlled switching element and in which a control circuit of the switching element includes a photosensitive member, all this in a manner such that the flash duration is influenced as a function of the brightness of an object exposed by the tube.
  • a known arrangement of the above-mentioned kind is described, for example, in German published application (Auslegeschrift) no. 1,288,428.
  • a quench tube is incorporated as a switching element.
  • the method carried out with this known arrangement is as follows: First the flash tube is rendered conducting by an auxiliary electrode so that flashing commences. When, after some time, sufficient light has been reflected by an object to be photographed, the switching element will be rendered conducting through the photosensitive member in the control circuit of this switching element so that the flash tube is extinguished. This flash tube is extinguished earlier as the illuminated object is closer and/or has a lighter color.
  • a drawback of the abovementioned known arrangement is that substantially the entire charge of the main capacitor flows away when the quench tube is actuated. This means that this main capacitor must be recharged to make the arrangement ready for taking the next flash photograph. This is a drawback.
  • An object of the present invention is to provide an arrangement in which the charge of the main capacitor is used more effectively.
  • an arrangement including an electronic flash tube from a previously charged main capacitor and in which a supply branch including said tube is shunted by a circuit provided with at least a controlled switching element and in which a control circuit of the switching element includes a photosensitive member, all this in a manner such that the flash duration is controlled as a function of the brightness of an object exposed by the flash tube, is characterized in that the circuit shunting the tube incorporates an auxiliary capacitor so that the main capacitor still retains a residual charge after flashing.
  • An advantage of the above-mentioned arrangement is that, when the switching element is actuated, the auxiliary capacitor is charged to substantially the same voltage value as the instantaneous voltage value of the main capacitor. The voltage on the main capacitor will then not decrease below the minimum operating voltage of the flash tube because the bridge across the flash tube is not a real short circuit, since it includes a capacitor.
  • auxiliary capacitor may be discharged, for example, through a resistor but this is not necessary.
  • the controlled switching element may be, for example, a quench tube.
  • the controlled switching element may be alternatively a controlled semiconductor switching element, for example, a thyristor.
  • the switching element is a thyristor and the shunt circuit also includes a resistor
  • the thyristor is shunted by a circuit which includes at least a diode whose pass direction is opposite to that of the thyristor and in which the condition is satisfied that C /C C times the initial voltage of the main capacitor is larger than the minimum operating voltage of the flash tube, in which: C is the capacitance of the main capacitor and C is the capacitance of the auxiliary capacitor in the series circuit shunting the flash tube.
  • an advantage of this preferred embodiment is that the voltage on the auxiliary capacitor is generally lower at the instant of extinguishing the flash tube than it would be without the above-mentioned diode shunt so that the auxiliary capacitor is discharged earlier and the arrangement is therefore sooner available for generating the next flash.
  • the auxiliary capacitor will first be charged after the switching element has been rendered conducting, the voltage across the capacitors still being above the minimum operating voltage of the flash tube after this distribution of the charge of the main capacitor over,
  • the main capacitor will supply further energy to the flash tube and the auxiliary capacitor will pass a current through the diode to the flash tube.
  • the control circuit of the thyristor in the shunt circuit at a slightly earlier instant, it can be achieved that the flash from the flash tube radiates the exact quantity of light in spite of this current flowing through the diode.
  • the mentioned light quantity is a quantity which is desirable in view of the distance between the camera and the object and the color of the object.
  • the residual charge of the main capacitor will not drop below that of the minimum operating voltage of the flash tube.. In practical cases this voltage is approximately Volts.
  • the reference numerals l and 2 denote connecting terminals which are intended to be connected to an arrangement for DC charging a capacitor 3 which is arranged between terminals 1 and 2.
  • the reference numeral 4 denotes an electronic flash tube. This tube is connected in series with the primary winding 5 of a transformer. The series arrangement of flash tube 4 and transformer winding 5 together shunt the capacitor 3. The flash tube 4 together with the transformer winding 5 are shunted by a series arrangement of a resistor 6, a thyristor 7 and a capacitor 8.
  • the thyristor 7 is shunted by the series arrangement of a resistor 9 and a diode 10.
  • the capacitor 8 is shunted by a resistor 11 having a high resistance.
  • the reference numeral l2 denotes the secondary winding of the transformer whose primary winding is denoted by reference numeral 5.
  • One end of this transformer winding 12 is connected to a diode 13 and a capacitor 14.
  • the other end of capacitor 14 is connected to the other end of the transformer winding 12.
  • the capacitor 14 is shunted by a series arrangement of a photosensitive resistor 15, a variable adjusting resistor 16 and a subsequent variable adjusting resistor 17.
  • the variable resistor 17 is in turn shunted by a capacitor 18.
  • FIGURE diagrammatically shows a control electrode of the flash tube 4 which is denoted. by the reference numeral 19. This control electrode is connected to a terminal 20. In addition a main electrode of the tube 4 is connected to a connecting terminal 21.
  • the operation of the circuit described is as follows. First the capacitor 3 is DC charged through the terminals 1 and 2 by an arrangement not shown. Subsequently, when taking a photograph and by simultaneously closing the camera contact a voltage is applied between terminals 20 and 21 by an arrangement not further shown. As a result a voltage is applied to the trigger electrode 19 so that the flash tube 4 is ignited. As a result a current will flow through the primary winding 5 of the transformer which is connected in series with the tube 4. Consequently, a voltage will also be generated in the secondary winding 12 so that capacitor 14 will be charged. The tube 4 lights an object while part of the light reflected by this object is incident on the photosensitive resistor 15. As a result the resistance of this cell 15 will decrease.
  • the second current circuit is constituted by capacitor 8, resistor 9, diode 10, resistor 6 and the tube 4.
  • the second current flows through the tube 4 in the last mentioned circuit in the direction of current flow determined by diode 10.
  • the resistor 1 1 in the circuit is a resistor which shunted the capacitor 8. This resistor is provided to ensure that the capacitor 8 does not remain in its charged state when a flash is effected and when this flash is extinguished. In fact, this would be detrimental for taking further flash photographs immediately thereafter.
  • a switching element may be arranged in the position of resistor 1 l.
  • the capacitor 3 had a capacitance of 600 F. in that case also the capacitance of the capacitor denoted by the reference numeral 8 was 600 F.
  • the capacitance of capacitor 14 and capacitor 18 was 20 1F each.
  • Resistor l6 and resistor 17 were both variable between approximately 50 and S Ohms. Resistor 6 had a value of approximately 0.28 Ohms. Resistor 9 had a value of approximately Ohms and resistor 11 had a value of approximately 50 k. Ohms.
  • the starting point was an initial voltage on the capacitor 3 of approximately 350 Volts direct voltage.
  • the minimum operating voltage of the electronic flash tube 4 was approximately Volts. Consequently, in this case the condition is satisfied that C,/C +C times the initial voltage of the capacitor 3 is larger than the minimum operating voltage of the tube, for 600/600+600 X 350 Volts is larger than 80 Volts.
  • the main capacitor 3 is not completely discharged, that is to say, a residual charge of approximately 80 Volts remains so that a battery may charge this capacitor rapidly to 350 Volts again.
  • the battery which is used for charging this capacitor 3, or any other device which serves for charging capacitor 3 need supply less energy so that this battery or any other device need not be replaced too soon.
  • 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.
  • C is the capacitance of the supply capacitor and C is the capacitance of the auxiliary capacitor.
  • 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.
  • 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.
  • 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 auxoperating voltage of the flash tube wherein: C is the capacitance of the supply capacitor and C is the capacitance of the auxiliary capacitor.
  • a control circuit as claimed in claim 1 further comprising a resistor connected in shunt with the auxiliary capacitor.

Landscapes

  • Discharge-Lamp Control Circuits And Pulse- Feed Circuits (AREA)
  • Stroboscope Apparatuses (AREA)
  • Exposure Control For Cameras (AREA)
US00086516A 1969-11-08 1970-11-03 Arrangement including an electronic flash tube Expired - Lifetime US3716753A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL6916883.A NL161032C (nl) 1969-11-08 1969-11-08 Inrichting voorzien van een elektronische flitslamp.

Publications (1)

Publication Number Publication Date
US3716753A true US3716753A (en) 1973-02-13

Family

ID=19808346

Family Applications (1)

Application Number Title Priority Date Filing Date
US00086516A Expired - Lifetime US3716753A (en) 1969-11-08 1970-11-03 Arrangement including an electronic flash tube

Country Status (9)

Country Link
US (1) US3716753A (fr)
JP (1) JPS4832726B1 (fr)
AT (1) AT316988B (fr)
BE (1) BE758643A (fr)
CH (1) CH527544A (fr)
FR (1) FR2069108A5 (fr)
GB (1) GB1328553A (fr)
NL (1) NL161032C (fr)
SE (1) SE354767B (fr)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3787704A (en) * 1970-02-20 1974-01-22 Loewe Opta Gmbh Electronic flash unit with controlled light energy
US3836818A (en) * 1973-02-22 1974-09-17 R Berglas Strobe light trigger circuit
US3878433A (en) * 1971-11-17 1975-04-15 Sato Koki Kk Photographic flashlight apparatus with improved automatic light termination means
US4019092A (en) * 1974-05-15 1977-04-19 Rollei-Werke Franke & Heidecke Photographic flash apparatus
US6064159A (en) * 1995-11-02 2000-05-16 Olympus Optical Co., Ltd. Power-saving stroboscopic device
US10976794B2 (en) 2017-12-21 2021-04-13 Carrier Corporation Low latency power supply for notification appliance synchronization

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4916421A (fr) * 1972-06-01 1974-02-13

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3340426A (en) * 1965-05-04 1967-09-05 Honeywell Inc Control system for terminating the discharge through a flash lamp
US3517255A (en) * 1968-07-25 1970-06-23 Honeywell Inc Flash apparatus with automatic light termination using light activated silicon controlled rectifier
US3541386A (en) * 1968-04-03 1970-11-17 Bosch Elektronik Gmbh Control system for terminating the discharge of a flash lamp

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3340426A (en) * 1965-05-04 1967-09-05 Honeywell Inc Control system for terminating the discharge through a flash lamp
US3541386A (en) * 1968-04-03 1970-11-17 Bosch Elektronik Gmbh Control system for terminating the discharge of a flash lamp
US3517255A (en) * 1968-07-25 1970-06-23 Honeywell Inc Flash apparatus with automatic light termination using light activated silicon controlled rectifier

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3787704A (en) * 1970-02-20 1974-01-22 Loewe Opta Gmbh Electronic flash unit with controlled light energy
US3878433A (en) * 1971-11-17 1975-04-15 Sato Koki Kk Photographic flashlight apparatus with improved automatic light termination means
US3836818A (en) * 1973-02-22 1974-09-17 R Berglas Strobe light trigger circuit
US4019092A (en) * 1974-05-15 1977-04-19 Rollei-Werke Franke & Heidecke Photographic flash apparatus
US6064159A (en) * 1995-11-02 2000-05-16 Olympus Optical Co., Ltd. Power-saving stroboscopic device
US10976794B2 (en) 2017-12-21 2021-04-13 Carrier Corporation Low latency power supply for notification appliance synchronization

Also Published As

Publication number Publication date
JPS4832726B1 (fr) 1973-10-08
DE2053411B2 (de) 1977-04-14
AT316988B (de) 1974-08-12
BE758643A (fr) 1971-05-06
DE2053411A1 (de) 1971-05-19
NL6916883A (fr) 1971-05-11
NL161032C (nl) 1979-12-17
GB1328553A (en) 1973-08-30
SE354767B (fr) 1973-03-19
CH527544A (de) 1972-08-31
FR2069108A5 (fr) 1971-09-03
NL161032B (nl) 1979-07-16

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