FR2470515A1 - POWER SUPPLY FOR AN ELECTRIC FLASH DEVICE - Google Patents

Abstract

A POWER SUPPLY DESIGNED TO PROVIDE THE VOLTAGE NECESSARY FOR THE OPERATION OF A LIGHTNING TUBE 27, FROM A BATTERY 10, INCLUDES IN PARTICULAR A CONTINUOUS-CONTINUOUS VOLTAGE CONVERTER B WHICH CHARGES A CONDENSER 18. THE CONVERTER IS EQUIPPED WITH A CIRCUIT J WHICH AUTOMATICALLY SHUT DOWN ITS OPERATION AT THE END OF A DETERMINED PERIOD, TO AVOID USING THE BATTERY FLOW. APPLICATION TO PHOTOGRAPHY.

Description

The present invention relates to a power supply for a device for

  electric flash, and it relates more particularly to a battery-operated power supply that uses a DC-DC converter having an oscillator circuit. Flash devices are now widely used in various types of optical devices including

  operation requires light in the form of lightning.

  In the field of photography, in particular, we use

  reads artificial light to illuminate an object to photograph. The light produced by the so-called flash tube is a form of artificial light that is

  widely used at the present time.

  it is common practice in electric flash devices to get a strong illumination for

  photographic applications by discharging a condensa-

  loaded into a flash tube filled with gas. A low voltage DC power source is generally employed in conjunction with suitable circuitry to provide the relatively high DC voltage required to charge the flash capacitor for each boot.

  flash tube. This charge requires considerable energy

  corn. Conversion with a good return of electrical energy

  Thus, light energy in the form of lightning is an important problem in these types of flash devices.

  In particular, electric flash devices

  usually employ a power supply in which a high-value output capacitor is charged,

  for a certain period of time, at a voltage of sufficient value

  to feed a photographic flashlight. These

  usually employs an element of communi-

  mechanical conversion in order to convert a voltage of>

  relatively low pile to give the unidirectional voltage

  relatively high, which is necessary for an element

  of use, such as for example the photogra-

  phic. It is easy to understand that under the conditions

  typical use of an electric flash device.

  that a significant part of the time during which the

  positive is in operation can correspond to a waiting time, that is to say the time that elapses after

  the power supply charged the capacitor to an appropriate value

  before the shutter of the camera is triggered, which discharges the capacitor into the tube

  flash. Meanwhile, the diet consumes energy.

  from the stack without producing any useful action.

  The loss of energy can be significant, particularly when the device includes transformers. As the battery ages, its output voltage decreases and the time required to ignite the flash tube increases. In addition, when the output voltage of the battery decreases due to aging, the device

  eventually become unable to prime the flash tube.

  According to the invention, the disadvantages indicated above can be eliminated by means of a feed

  in which the current coming from the pile is self-

  interrupted without using a mechanical switch.

  of the power source, when the charge capacitor is charged to a predetermined value. However, in

  the power supply of the invention in which the current

  from the energy source is automatically interrupted, the primary current of the transformer decreases after a predetermined time interval from the start of the energy source, and the power source is then disconnected when its current reaches a predetermined value. In this case, it is necessary to adjust the instant of oscillation stop of an oscillator circuit, in order to regulate the duration of the flash, because the duration of the flash produced by a flash tube of a device

  flash is variable from one device to another.

  The main purpose of the invention is to realize

  an improved battery-powered power supply that eliminates the previous drawbacks, that is to say

  a power supply -which offers high performance and a-

reduced cost.

  The aim of the invention is more precisely to achieve

2470515 -

  a high performance power supply for a

  electric flash, which is able to regulate the

  so much oscillation stop, and thus the instant of interruption of the current, when the electric charge of a storage capacitor reaches a predetermined value. Another object of the invention is to provide an economical and high performance power supply for an electric flash device which consumes little electrical energy, thanks to the automatic interruption of the current coming from a battery, this power supply being employment

  easy and having a high efficiency.

  The invention also aims to achieve a-

  power supply for an electric flash device in which the moment of interruption of the power source current can be set in a range-extended to

means of a simple circuit.,.

  These aims of the invention and the advantages thereof are achieved by a perfected power supply in which the voltage from a power source corresponding to a relatively high battery voltage

  bass is converted into a unidirectly

  relatively high, which is intended to be applied

  to a charge. The battery voltage is applied to a cir-

  baked transistor oscillator. A suitable bias voltage is applied to a control electrode of the transistor of the oscillator circuit, via a

  switch, to oscillate the oscillator circuit.

  The output signal of the oscillator is rectified and is applied to a DC current circuit under

  the form of a unidirectional output voltage.

  at the terminals of the circuit of use can be applied

  to an element of use such as a photographic flashlight

phic or a similar element.

  According to the invention, a power supply for a flash device comprises a power source circuit,

  dc system, comprising a battery, a con-

  voltage converter which is intended to convert into AC voltage a DC voltage which is supplied by

2 2470515

  the DC power source circuit, a rectifier that rectifies the AC voltage, and a use circuit including an electric charge storage circuit for storing an electrical charge from the rectifier circuit and providing power an element of use. This power supply furthermore comprises current interruption means which are intended to automatically interrupt the current that the circuit of

  DC power source provides the circuit with

  when an electric charge is stored in the electric charge storage circuit, means for

  adjustment of an electrical quantity to adjust a large

  An electrical generator is applied to an oscillator element of the voltage converter circuit, when the DC power source circuit supplies current to the utilization circuit and control means of the current interruption time. which regulate the interruption time

  current by the current interruption means.

  - Other features and advantages of the invention

  tion will be better understood from reading the description

  will follow of embodiments and with reference to the accompanying drawings in which

  Figure t is a detailed diagram of a food

  for a corresponding electric flash device

to the invention. -

  Fig. 2A is a graph showing a characteristic relating to the current of the energy source,

according to the invention.

  Figure 2B is also a graph that shows

  a characteristic relating to the current of the energy source

in accordance with the invention.

  Figure 3 shows a modified version of the

  of the flash device of Figure 1.

  Figure 4 is a detailed diagram of another

  version of the power supply corresponding to the invention.

  Figure 5 is a detailed diagram of another

  version of the power supply corresponding to the invention.

  Figure 6-is a detailed diagram of another -

  version of the power supply corresponding to the invention.

  The power supply shown in FIG. 1 comprises a DC power source circuit A, a voltage converter circuit B for converting and raising a voltage from the DC power source circuit. A, to give an alternating voltage, a rectifier circuit C for straightening the

  high alternating voltage that comes from the conver-

  voltage strainer B, an electrical charge storage circuit

  D, intended to store electrical energy which is

  supplied in the form of direct current by the rectifying circuit

  C, and to supply electrical energy to a circuit of

  which comprises a flash tube, a trigger signal generating circuit E, for triggering the flash tube by applying a trigger signal on a

  trigger electrode of the flash tube, a circuit for use

  which is in the form of a flash tube circuit F comprising a flash tube, a voltage signal adjusting circuit G for adjusting a voltage wave of the voltage converter circuit B, and a control circuit oscillation stop instant J for adjusting the oscillation stop time of an oscillator and the interruption of

current of the energy source.

  In more detail, the source circuit

  DC power supply A comprises a battery 10. The circuit

  cooked voltage converter B basically comprises a

  oscillator circuit OC, an oscillation start circuit

  OS and an oscillation stop circuit ST. In a way

  In more detail, the voltage converter circuit B

  takes an oscillation transformer 11 which comprises at least two windings, such as a primary winding 11a and a secondary winding 11b, an oscillation switching element which is in the form of a high-performance silicon transistor 12, a capacitor of

  oscillation start 13, a limiting resistor of

  current 14 and an oscillation start switch which is in the form of a mechanical switch such as a pushbutton switch 15, a terminal of which is connected to the terminal of the resistor 14 which is not

  connected to the transformer. A winding terminal

  may lia of swing transformer-11- is directly

  connected to a positive terminal of the battery 10 and the other terminal

  the primary winding 11a is connected to a collector electrode of the oscillator transistor 12, in the

  aim of forming the oscillator circuit OC. A terminal of the

  secondary bearing 11b is connected to a control electrode which is constituted by the base electrode of the

transistor 12.

  The voltage converter circuit B is essentially

  actually an oscillator circuit of the voltage reaction type

  if we. The oscillator transistor 12 is a high performance NPN type transistor, as discussed above, and has a high internal resistance between the emitter and the collector when in the off state. The leakage current of the transistor 12 is therefore extremely low and it is almost zero in comparison with that of a germanium transistor. A mechanical switch in the form of a push-button switch 16 is connected

  between the base electrode and the emitter electrode of the

  sistor 12, to form the oscillation stop circuit ST.

  The oscillation start circuit OS is formed by the resistor 14 and the oscillation start switch

  15 closed by manually depressing its push button.

  This switch is of the type open at rest and it opens when you stop pressing its button. The oscillator transistor 12 is a high performance NPN type silicon transistor in which the leakage current is low, for example in the range of 0.1 to 0.2 pvA, or

close to zero. -

  The rectifier circuit C has an electrical element

  unidirectional ring which is in the form of a diode 17 having a cathode electrode connected to it.

  the other terminal of the secondary winding 11b of the transforma-

  The diode 17 is mounted to be connected in the opposite direction with respect to the polarity of the battery 10. The

  charging-electric storage circuit D comprises a

  main storage denser 18-, a limiting resistor

  19, an indicator lamp in the form of a neon lamp 20, which is connected in parallel with the main storage capacitor 18, via the current limiting resistor 19, and a capacitor 21 which is connected in parallel with the neon lamp 20. A terminal of the capacitor 18 is connected to the anode electrode of the diode 17 and the other terminal of the capacitor 18 is connected to the electrode of the emitter of the transistor 12, as well as to a negative terminal

from the pounded 10.

  The trigger signal generating circuit E comprises a load resistor 22, a terminal of which is connected to the terminal of the main storage capacitor 18 which is connected to the anode of the diode 17, a trigger capacitor 23 having a terminal connected to it. to the other

  terminal of the load resistor 22, a resistance of

  24 which is connected between the other terminal of the terminal

  23 and the negative terminal of cell 10, an itransfor-

  triggering device 25 which has a primary winding

  25a and a secondary winding 25b, and an interrup-

  The synchronization timer 26, which is connected in parallel, is designed to be closed and open in synchronism with a camera shutter (not shown in the drawing). The use circuit which is in the form of a flash tube circuit F comprises a flash tube 27, filled with gas. The flash tube 27 has two

  main current conduction electrodes, 27a, 27b, -

  and a trigger electrode 27c which is placed near

  flash tube 27, but outside the latter.

  trigger trode 27c is connected to a terminal-of

the secondary winding 25b.

  An oscillation control circuit -G is connected between the base circuit and a connection point J2 between the cathode electrode of the diode 17 and the main storage capacitor 18. The oscillation control circuit G comprises an oscillation control capacitor 28 which is connected between the base electrode of the transistor 12 and 1.

  connection point J2, via a resistor

  In addition, an oscillation indication circuit H for indicating the operation of the voltage converter circuit B is designed to be connected in parallel with the secondary winding 11b of the oscillation transformer 11. The oscillation indication circuit H comprises the following elements connected in series: a protection resistor 30, a diode 31 and an indicator lamp which is in the form of a

neon lamp 32.

  The most important feature of the invention

  tion consists in the use of means for adjusting the instant of interruption of the current, the purpose of which is to

  adjust the moment of interruption of the current, when the

  from the power source circuit

  tinu is automatically interrupted. So, a winding

  33 is wound on the oscillator transformer.

  11 to detect an electrical quantity of the trans-

  oscillation trainer 11. In the diet of the figure

  1, the detection winding 33 is wound on the transfor-

  oscillator 11 and an impedance element constituted by a variable resistor 34 is connected to the sense coil 33 so as to form an oscillation stop instant setting circuit J. The operation is as follows . The distributed capacitance of the oscillation transformer 11 and the

  oscillation capacitor-start oscillation voltage

  13 to switch the transistor 12 to start the oscillation operation of the oscillator circuit

  OC. After starting the oscillation operation, the condensation

  The purpose of the oscillation start controller 13 is to restrict the oscillation voltage, since the experimental data show that this voltage is too high. A reaction voltage is applied on the base of the transistor 12, from the secondary side of the transformer

of oscillation 11.

  We operate manually. the switch 15 so as to place it in the closed or open state. When

  switch 15 is in the open state, the oscillation circuit

  OC driver does not start its oscillation operation, because the oscillator transistor 12 is off. When the switch 15 is instantaneously closed, the base electrode of the transistor 12 is polarized so as to cause the conduction of this transistor, because the transistor 12 receives a base current from the stack 10 of the circuit of energy source A, through the resistor 14 and the switch 15. When the transistor 12 becomes

  conductor, a current flows through the primary winding

  - Re lia of the oscillation transformer 11, and in the circuit

  collector-emitter of transistor 12, from stack 10.

  At the same time, the current flows in the base circuit.

  emitter of the transistor 12, the battery 10 and the resistor 14, and an electric charge accumulates on the capacitor 13, so that the voltage converter circuit B starts to

  oscillate and produces a high alternating voltage which

  in the secondary winding 11b. Induced voltage also occurs in the sense coil 33. In this case, the oscillation voltage due to the parasitic capacitance of the transformer windings 11 or the oscillation start capacitor 13 is also used to switch the oscillator transistor. 12 in the conductive state and in the off state. The high AC voltage is rectified by the diode 17 of the rectifier circuit C to produce a

high DC voltage.

  Since each winding of the oscillation transformer 11 is wound so that the base current increases, the transistor 12 becomes conductive under the effect

  a positive reaction-produced by the transformer 11.

  The collector current increases almost linearly with time. The transient component of the base current decreases when the base current reaches a peak value which is determined by the induced voltage and

  14. In other words, the increase of the neck.

  collector becomes non-linear, then this current does not increase. In addition, the increase of the collector current of the transistor 12 is also stopped by the

  saturation of the magnetic circuit of the transformer 11.

  Thus, the base current of the transistor 12 decreases and the

  collector current then decreases rapidly. The decrease

  tion of the collector current has the effect of blocking the transistor 12. When the transistor 12 is blocked, the current

  which flows in the primary winding 11a of the transforma-

  Oscillator 11 is rapidly interrupted and the L x Ip energy stored in the oscillation start capacitor 13 appears on the base electrode of transistor 12 in the form of a reverse voltage due to the nature of the primary winding 11a. In the above expression, L1 is an inductance (H) and I is 1p the peak value of the collector current. In this case, the charging current of the capacitor 13 becomes an oscillating current if the existing conditions remain, because the transistor 12 is off. Under these conditions, the current flowing in the primary winding 11a of the oscillation transformer 11 also reverses after a

  half-cycle of the oscillation of the condenser charge current.

  13, and a voltage appears on the base electrode

  of the transistor 12. The transistor 12 is again polarized.

  in the conductive state, which makes restart the opera-

  oscillation circuit of the oscillator circuit OC.

  As indicated above, when the oscillation start switch 15 is momentarily closed, the current flows from the battery 10 of the circuit.

  DC power source A, in the direction of the con-

  13, via the resistor 14 and the switch 15, and a positive potential appears on the base electrode of the transistor 12. The transistor 12 becomes conductive under the effect of the positive potential of the electrode base and circuit oscillation operation

  Oscillator OC continues because of the coupling-electromagnetic

  which is established in the transformer 11 by the energy stored in the inductance of this transformer, and the fact that the current required for the oscillation penetrates into the transformer.

  the base electrode of the transistor 12.

  In addition, it is not always necessary for the switch 15 to go to the open state immediately after the end of its function corresponding to the closed state. This switch can be a switch that opens after a predetermined time interval, for example at the

  about three seconds to thirty minutes.

  The diode 31 of the oscillation indication circuit

  H rectifies the alternating voltage of the secondary winding

  In this case, the voltage applied to the neon lamp 32 takes a value of half because of the straightening operation of the neon lamp 32.

  the diode 31, and the power consumed is decreased. The decrease

  The effect of increasing the power consumption is to increase the reaction current, so that the transition time of the transistor 12 to the conducting state becomes long. The neon lamp 32 of the oscillation indication circuit H is illuminated and

  the illumination of this lamp confirms the oscillation of the

  baked OC oscillator. The inactive state of this circuit can also

  be confirmed by the fact that the neon lamp 32 is

not enlightened.

  The current resulting from the recovery made

  the rectifier circuit C flows in a loop of

  which is formed by the secondary winding 11b of the oscillation transformer 11, the base-emitter circuit of the

  transistor oscillator 12, the main storage capacitor

  18 and the diode 17. This current has the effect of storing

  an electrical charge in the main storage capacitor 18 of the electric charge storage circuit D, with the polarity shown in FIG. 1, and simultaneously an electric charge also accumulates in the oscillation control capacitor 28 In addition, an electric charge is stored in the trip capacitor-23 due to the current flowing in a current loop formed by the secondary winding 11b, the base-emitter circuit of the

  transistor 12, the trigger capacitor 23, the resistor

22 and the diode 17.

  We will now describe the stopping of the operation of the voltage converter circuit B, based on experimental data. A current of the order of 50 mA circulated initially in the main storage capacitor 18,

  through the diode 17, the secondary winding

  11b of the transformer 11 and the base-emitter circuit of the transistor 12 and, simultaneously, by the diode 17 and the capacitor 13 when the oscillator circuit OC begins the oscillation operation. The current flowing in the

  main storage capacitor 18 gradually decreases-

  up to 150 yA as the accumulation of

  the electric charge in the main storage capacitor

  18. When the current of capacitor 18 decreases

  up to 150 pA, the base current of transistor 12 of the circuit

  The voltage converter B also decreases, so that the current flowing from the battery 10 to the primary winding 11a of the transformer 11 is automatically interrupted by the transistor 12, because the base current of the transistor 12 decreases until at a lower value

  than the current required for the switching operation

tion. -

  When the oscillator circuit OC starts the operation

  ration of oscillation, electromagnetic energy is

  also induced in the sensing winding 33 of the circuit

  oscillating stop timing setting: J, which circulates a current in the sense winding 33 and the variable resistor 34, under the effect of the energy that

  is induced in the sensing winding 33. The current -

  which circulates in the variable resistor 34 consumes electromagnetic energy, which stops the oscillation operation of the oscillator circuit OC. The oscillation stop time can be set by changing the value of the

  variable resistor 34 of the instant setting circuit

  J. When stopping a value of 5004L-

  for the variable resistor 34, the current flowing from the battery 10 to the primary winding 11a initially has a value of 3 A and it progressively decreases to 100 mA, which is lower than the current required to make

  operate the OC oscillator circuit which includes the

  sistor oscillator 12, when an electrical charge is stored in the main storage capacitor 18 of the electric charge storage circuit D, as shown in a curve 11 in Figure 2A. The oscillation operation of the oscillator circuit OC ceases at time T1 which corresponds to the current value of 100 mA, and the current that comes from the battery 10 is thus interrupted. When a value of 10 k is set for the variable resistor 34, the energy consumed is less than when the variable resistor 34 has the value

  indicated above, and the reaction current to the elec-

  base trode of the transistor 12 becomes high. Thus, the current in the primary winding 11a is initially 3A and decreases to 50mA at time Tn, as shown in curve 12 in FIG. 2B. and the current that

  comes from the stack 10 is then automatically interrupted.

  In FIGS. 2A and 2B, TO designates an instant at which the oscillation operation begins, T1 designates an oscillation stop instant in the case where the value R1 of the variable resistor 34 is 500 XL and T designates a moment n-

  oscillation stop in case the value of the resistance

  R2 is 10 kfl. We have the following relations: R1 <R2 and Tn n <T1. It is therefore possible to adjust the oscillation stop instant by adjusting the value of the variable resistor 34. When the main storage capacitor 18

  of the electric charge storage circuit D is entirely

When charged to the predetermined and appropriate voltage, the neon lamp 20 illuminates, indicating that the device is ready to ignite the flash tube -27. We can then

  initiate the flash tube 27 by closing the switch 26 asso-

  attached to the shutter of the camera. It is easy to understand that it suffices that this closure is momentary,

  during the shutter operation of the camera

  phic. The closing of the switch 26 has the effect of discharging by the switch 26 and the primary winding 25a

  the electric charge present in the trigger capacitor

  25. A high voltage pulse, such as for example 3000 V, is then induced in the secondary winding 25b of the

24705 1-5

  trigger transformer 25. The high voltage that is

  induced in the secondary winding 25b of the transformer

  mateur 25 appears on the trigger electrode 27c of the

  flash tube 27 and ionizes a portion of the gas contained in the

  Flash tube 27. The main storage capacitor 18 then discharges into the gas between the main current conducting electrodes 27a and 27b, producing a flash of light. Once the main storage capacitor 18 has discharged, the voltage at the terminals of this capacitor takes a low value, so that the electrical charge which

  is stored in the oscillation control capacitor-

  28 is discharged by the base-transmitter circuit of the trans-

  tor 12 (and the oscillation start capacitor 13), the main storage capacitor 18 (and the flash tube 27) and the capacitor 28. The discharge of the capacitor 28 reveals a positive potential in the basic circuit

  of the transistor 12. Under these conditions, the oscillation-circuit

  OC enters the active state, or the inactive state in

  some cases. In both cases, the transistor 12 becomes

  driver under the effect of the positive potential of its base electrode and the oscillation operation of the oscillator OC starts again. On the contrary, the operation of the oscillator OC can be stopped effectively and quickly, if it is

  desires, by closing the oscillation stop switch 16.

  Indeed, the oscillation start capacitor 13 is shortcircuited by the switch-16, although the oscillation of the oscillator circuit OC starts automatically when the main storage capacitor 18 discharges the electric charge by the flash tube 27. In this case, case, the current of

  leakage is less than a few microamperes, and the interrup-

  Thus, because of the use of the high-performance transistor 12 in the voltage converter circuit B of the power supply of FIG. 1, it avoids any other source of energy source. loss of battery power when the switch 15 remains in the closed state for a long time. It can therefore be seen that good characteristics are obtained for the supply. In addition, the structure of the circuit is simplified and the circuit can be manufactured easily and economically, in comparison with the power supply of the prior art, that the oscillator circuit OC can be operated by closing

  instantly the start-oscillation switch 15.

  In addition, it is easy to operate the power supply shown in FIG. 1, since the photographer does not have to perform an action to

  prepare the next flash of the flash tube 27, since the cir-

  baked oscillator OC begins the oscillation operation after the flash tube 27 has produced a flash, even when the current that comes from the energy source A is interrupted

  and even when the oscillation circuit OC ceases to oscillate.

  The power supply of FIG. 1 more particularly

  the real advantage of being able to obtain

  define defined characteristics for the circuit-converts--

  voltage B by adjusting the impedance value of the element.

  impedance of the stop time setting circuit

  of oscillation J, thanks to which this power supply is applied

  cable to all flash devices. Another advantage of this power supply is that the oscillation stop instant setting circuit J makes it possible to make an adjustment over an extended range, by the choice of the impedance value of the element at impedance-which is constituted by

the variable resistance 34 ..

  Figure 3.shows a modified version of the

  Figure 1. In this diet, a trans-

  Oscillator 11 comprises a primary winding 11a, a secondary winding 11b and a control winding 11c. The control winding 11c is connected between a base circuit and a positive electrode of a battery of a DC power source circuit A. A terminal of the control winding 11c is connected to the electrode positive 10 through a resistor

  14 and an oscillation start switch

  15, while the other terminal of the control winding

24705 1S

  of lic is connected to a base electrode of a transistor

  oscillator 12 and to the secondary winding 11b of the transformer

oscillation meter 11.

  In the power supply of FIG. 2, the transistor 12 receives the base current from the battery of the DC power source circuit A via

  of the resistor 14, the switch 15 and the winding

  control unit of the oscillation transformer 11, this

  base current which has the effect of causing the tran-

  When the transistor 12 becomes conductive, a current flows from the cell 10 and passes through the primary winding 11a of the oscillation transformer 11 and the collector-emitter circuit of the transistor 12. A current flows simultaneously through the lic control winding, the base-emitter circuit of the transistor 12, the battery and the resistor 14. An electric charge accumulates

  in the capacitor 13, so that the circuit converts

  voltage B begins to oscillate and produces a voltage.

  high alternative that appears in the second winding.

  re l1b. The control winding here serves to stabilize the oscillating operation of the oscillator circuit OC. In more detail, when the oscillator circuit OC begins to oscillate, the electromagnetic energy of the oscillation transformer 11 is applied to the base circuit of the transistor 12, from the control winding

  11c, in the form of a reaction stream. This food

  Therefore, the advantage is that the oscillation operation is stabilized and offers advantages.

  similar to those of the diet of Figure 1.

  Figure 4 represents another embodiment of

  of the invention and, similarly to the power supply of FIG. 1, that of FIG. 4 comprises a DC-A power supply circuit comprising a battery

  , a voltage converter circuit B, for converting

  firing a continuous voltage from the battery 10 into an alternating voltage

  native, a rectifier circuit C for straightening the voltage

  alternation from the voltage converter circuit

  B to give a continuous voltage, a circuit of

24705 15

  electric charge terminal D, for storing the electric charge to be supplied to a utilization circuit, a trigger signal generating circuit E for triggering a utilization circuit which is in the form of a circuit flash tube F and an indication circuit

  This feed also includes a cir-

  fired stop timing of J oscillation stop intended to

  set the oscillation stop time of an oscillation circuit

  OC converter of the voltage converter circuit B, and the circuit J is connected to the output side of the voltage converter circuit B. In more detail, the oscillation stop instant setting circuit J comprises a winding circuit

  detection 33 which is on the secondary side of a transfor-

  oscillator 11 and an impedance adjuster

  which is in the form of a variable resistor 34.

  A terminal of the sense winding 33 is connected to a terminal of a secondary winding 11b and to a base electrode of an oscillator transistor 12. The other terminal of the sense winding 33 is connected to a terminal the variable resistor 34. The other terminal of the variable resistor 34 is connected to the secondary winding 1-lb of the oscillation transformer 11 and to the base electrode of the transistor 12, as well as to a tube at the neon 32 of the oscillation indication circuit H. The operation is as follows. When an oscillation start switch is momentarily closed, a current is initially flowing from the battery 10 of the DC power source circuit A,

  oscillation start capacitor 13, through

  of a current limiting resistor 14 and the switch 15, which has the effect of storing a

  electric charge in the oscillator start capacitor

  13. An oscillator transistor 12 becomes conductive under the effect of the electric charge of the capacitor 13 and

  the oscillator circuit OC begins to oscillate. Under the effect.

  of the oscillating operation of the oscillator circuit OC, a high alternating voltage is induced in the winding

  oscillation transformer secondary 11.b.

  alternating current is rectified by a diode 17 of the rectifier circuit C and a direct current flows in a loop which is formed by the secondary winding 11b, the base-emitter circuit of the transistor 12, a main storage capacitor 18 and the diode 17. At the same time a current flows in a current loop which is formed by the secondary winding 11b, the base-emitter circuit of the

  transistor 12, a protection resistor 24, a capacitor

  Tripod 23 and Diode 17. Main Storage Capacitor and Trip Capacitor

23 are thus loaded.

  When high AC voltage is induced

  in the secondary winding 11b of the oscillator transformer

  11, an alternating voltage is also induced in the sense winding 33, which circulates a current in the variable resistor 34. The electrical energy

  which is induced in the secondary winding 11b and the

  detection bearing 33 is consumed by the current that

  circulates in the variable resistor 34 and, in addition, the

  of polarization which must be applied to the circuit of

  base decreases as a result of the drift towards

  Thus, the oscillation stop instant setting circuit J operates in a manner similar to that of the circuits J of the described embodiments.

  above. In the diet of Figure 4, we can use

  part of the secondary winding llb of the transfor-

  oscillation meter It as a detection coil

  33, forming a catch on the secondary winding llb.

  It can be seen that the manufacture of the transformer

  It is easy because it takes just one

on the secondary winding llb.

  FIG. 5 represents a corresponding feed.

  to the invention which is even more effective. In the embodiment of FIG. 5, the power supply also comprises a DC power source circuit comprising a battery 10, a voltage converter circuit B comprising an oscillation transformer 11 and intended to convert a voltage continuous from the energy source circuit A to an alternating voltage, a rectifier circuit C for rectifying the alternating voltage which comes from the voltage converter circuit B, an electric charge storage circuit D comprising a capacitor of storage

  main stage 18, a trigger signal generating circuit

  E, a flash tube circuit F and an oscillation stop instant setting circuit J.

  oscillation stop instant setting J is placed on the side -

  of the input of the voltage converter circuit B. The circuit

  It is thus formed by a primary winding 11a of the oscillation transformer 11 and by a variable resistor 34 which is

  connected in parallel to the primary winding lla.

  In the diet that is represented on the

  In FIG. 5, an electrical charge is applied to a capacitor

  13 from the battery 10, via a current limiting resistor 14 and a switch

  start of oscillation -15- when closing this interrup-

  tor. When the charging voltage of the capacitor 13 reaches the enable voltage of a transistor 12, this transistor becomes conductive, which causes the oscillator circuit to pass.

  OC in the active state. As a result of the passage of the oscil-

  in the active state, a current flowing in the winding

  primary element 11a of the oscillation transformer 11, and a high alternating voltage is induced in a secondary winding 11b. The high AC voltage is rectified by the rectifier circuit C to store an electric charge in the main storage capacitor 18 and

  trigger capacitor 23. When the electrical charge is

  the current is stored in the main storage capacitor 18, the current flowing in the secondary winding decreases and the base current of the transistor 12

  decreases in accordance with the decrease in current in the coil.

  Secondary 1b. The decrease in the basic Polish current

  turn the transistor off, which automatically stops

  only the oscillation operation. -

  Although the current that the 10-cell provides to

2-470515

  the primary winding 11a is initially about 3A,

  the current of the primary winding 11a gradually decreases

  as the charge of the capacitor

main storage 18.

  The oscillation stop instant setting circuit

  tion J is formed by the primary winding 11a of the transfor-

  oscillation meter it and the variable resistor 34.

  The electrical energy that is induced in the winding

  primary l1a is consumed by the variable resistor 34.

  In this case, the electrical power that is consumed in

  the transformer 11 varies depending on there-difference -

  impedance of the closed circuit-that form the primary winding

  mayor and variable resistance 34. As a result,

  a reaction voltage which is applied to the base electrode of transistor 12 from the oscillation transformer 11

  varies according to the value of the variable resistor 34.

  In this case, when the value of the resistor 34 is

  ble, the energy that is consumed in winding 11a and the resistance 34 is high, while it is low in

  the case where the value of the resistor-34 is high.

  In this supply, the variable resistor 34 is connected to the primary winding 11a of the transformer 11 to form the ci. The advantage of FIG. 5 is that the power supply of FIG. 5 has advantages that consist in the fact that the number of elements

  is reduced and in that the circuit structure of the

  tif is simplified, since the primary winding

  is used as a detection coil. This food

  Moreover, it offers the same advantages as

previous realization.

  FIG. 6 represents another embodiment

  of the food which corresponds to the invention.

  In FIG. 6, an oscillation stop instant setting circuit is placed on the output side of a voltage converter circuit B and in the base circuit.

  of a transistor 12. As shown in Figure 6, a. ele-

  with variable impedance in the form of a

  variable resistor 34 is connected between a secondary winding

2 4 70 5 1 5

  11b of an oscillation transformer 11 and the base-transmitter circuit of the transistor 12. A terminal of the variable resistor 34 is connected to the secondary winding ilb and

  the other terminal of the resistor 34 is connected to an elec-

  transistor emitter trode 12. The control circuit

  of stop of oscillation stop J is thus formed by the

  secondary bearing 11b of the transformer 11 and by the

variable resistor 34.

  The operation is as follows. A tension

  high alternative is induced in the secondary winding.

  11 of the oscillation transformer 11 when the cir-

  baked voltage converter B goes into the active state. The induced voltage is rectified by a rectifier circuit C

  and an electric charge is stored in a condensate

  The main storage capacitor 18 of an electric charge storage circuit D. When the main storage capacitor is charged, the voltage converter circuit B ceases to operate and the current from the battery 10 is thus automatically interrupted. In this case, a portion of the current for the base electrode of the transistor 12 is derived by the variable resistor 34 and consumed. We

  can therefore set the oscillation stop instant and the

  so much interruption of the current by choosing the value of

the variable resistor 34.

  In this power supply, the oscillation stop instant setting circuit J has a structure

  simplified and is easy to build, because it resists

  variable voltage 34 is only connected between the secondary winding 1b of the oscillation transformer 11 and

  the basic circuit of the transistor 12.

  Although NPN transistors are used in the above embodiments, PNP transistors may also be used in accordance with the invention. We can then perform the same operations-and get

the same benefits.

  Naturally, various modifications may be made by those skilled in the art to the devices and methods which have just been described solely by way of nonlimiting examples, without departing from the scope of the invention.

Claims (14)

  1. Power supply for an electronic flash device   comprising a current power source circuit   continuous circuit (A) comprising a battery (10), a circuit converting   voltage converter (B) for converting a DC voltage from the DC power source circuit   at an alternating voltage, a rectifier circuit (C)   born to rectify the AC voltage coming from the circuit   voltage converter, and a common utilization circuit   taking an electric charge storage circuit (D)   intended to store an electrical charge from the cir-   baked rectifier and to apply electrical energy to an element of use, characterized in that it further comprises current interruption means for automatically interrupting the current as the dc power source circuit provides to the utilization circuit when an electrical charge is stored in the electric charge storage circuit, electrical magnitude control means (G) for adjusting a   electrical quantity which is applied to an oscillating element   tion of the voltage converter circuit, when the DC power source circuit supplies current to the use circuit, and current interrupting current control means for adjusting the interruption time. current by the current interruption means.   2. Feed according to claim 1, characterized   in that the voltage converter circuit com-   takes an oscillation transformer (11) which has a primary winding (11a) and a secondary winding   (11b), and an oscillator circuit (OC) which comprises a   oscillating switching device (12) which is connected to the DC power source circuit battery via the primary winding and which -possesses   a high leakage resistance when the oscillation operation   oscillation circuit is stopped, this element of   oscillation switching belonging to the means of interrup- :: 2 4 7 0 5 1 5 current flow.   3. Feed according to claim 1, characterized   in that the means for controlling the instant of interruption of the current comprises an oscillation stop instant setting circuit (J) which comprises a winding   detection device (33) for detecting a   voltage converter circuit, -; and an impedance setting element (34) for adjusting the current which   circulates in the sensing winding.   4. Feed according to claim 1, characterized   in that the oscillation stop instant setting circuit comprises a detecting winding (33) which   is placed on the oscillation transformer (11) of the cir-   baked voltage converter, and an impedance element   variable (34) which is connected to the sense winding.   5. Feed according to claim 1, characterized   in that the oscillation stop instant setting circuit comprises a primary winding (11a) of an oscillation transformer (11) of the voltage converter circuit, and a variable impedance element (34). who is   connected to the primary winding.   6. Feed according to claim 3, characterized   in that the oscillation stop instant setting circuit is placed at the output of the voltage converter circuit and comprises a detecting winding (33) for detecting an output electrical magnitude of the voltage converter circuit and a setting element   impedance (34) which is connected to the detector winding tion.   7. Feed according to claim 6, characterized   in that the oscillation stop instant setting circuit comprises a detecting winding (33) which is connected to a secondary winding of an oscillation transformer (11) and an adjusting element impedance (34)   which is connected between the sensing winding and a cir-   basic firing of a transistor (12) of an oscillator circuit (OC) .:   8. Feed according to claim 6, characterized 24705 15   in that the oscillation stop instant setting circuit comprises a secondary winding (11b) of the oscillation transformer and a variable resistor (34) which is connected to this secondary winding as well as to a base circuit emitter of an oscillator transistor (12).   9. Feed according to claim 1, characterized   in that it comprises an oscillation control circuit (G) for controlling the operation of the voltage converter circuit.   10. Food according to claim 9, characterized   characterized in that the oscillation control circuit com-   takes an oscillation control capacitor (28) which is intended to apply a bias voltage on a   control electrode of the oscillating-switching element   oscillator circuit (12) when a main storage capacitor (18) of the charge storage circuit electric discharged.   11. Feed according to claim 10,   characterized in that the oscillation control capacitor   The connection (28) is connected between the control electrode and a connection point between a rectifier circuit (C) and the electric charge storage circuit (D).   12. Feed according to claim 1,   tered in that it also includes an indi-   oscillation cation (H) for indicating the state of oscillation   tion of the voltage converter circuit.   13. Power supply according to claim 12, characterized in that the oscillation indication circuit   is a series circuit that is connected to a secondary winding   1 (11b) of an oscillation transformer (11) and having a protection resistor (30), a diode (31) and a neon tube (32).   14. Food according to Claim 2, which is   characterized in that the oscillation transformer comprises   furthermore a control winding (1c) for stabilizing   read the oscillation operation of the oscillator circuit.