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
  • H05B41/34—Circuit arrangements in which the lamp is fed by pulses, e.g. flash lamp to provide a sequence of flashes

Definitions

• the invention relates to a generator of light flashes and, more particularly, of ultraviolet light flashes, that is to say a device generating light flashes of which at least part of the wavelength is included in the band. ultraviolet wavelengths, between 120 and 380 nanometers.
• the invention relates more particularly to a generator of germinicidal light flashes, in the wavelength band 240 to 300 nanometers.
• ultraviolet flashes of this wavelength band can destroy pathogens present on a support or on an organism when the light power emitted by the flashes is sufficient.
• the invention relates more specifically to a light flash generator comprising at least one xenon lamp.
• a xenon lamp conventionally consists of a hermetic tube, generally made of quartz, incorporating xenon and two electrodes: an anode and a cathode. Light flashes are obtained by generating an electric discharge arc between the two electrodes and through a xenon plasma which transforms the electric energy into light energy.
• document FR 2 890 233 describes the use of a xenon lamp with an inter-electrode distance of between 150 and 200 millimeters, a voltage discharge between 2,500 and 3,500 volts and an additional voltage between 22,000 and 26,000 volts.
• This discharge voltage is obtained by discharging a capacitor arranged in an electric discharge circuit ensuring the charging and discharging of the capacitor.
• the capacitor is charged by the electric discharge circuit and the electric discharge arc can only be generated when the voltage across the capacitor is sufficient to create the electric arc. discharge.
• This ionization phase results from a first ionization electric arc generated between the two electrodes by means of a third ionization electrode.
• This ionization electric arc has very low energy compared to that of the discharge electric arc.
• the ionization electric arc can be generated for a period of between 10 and 100 microseconds.
• Certain xenon lamps thus use an alternation between an ionization electric arc and a discharge electric arc to create successive flashes of light.
• some xenon lamps also use one or more electric pre-arcs between the ionization electric arc and the discharge electric arc. These electric pre-arcs have energy values intermediate between the ionization electric arc and the discharge electric arc so as to improve the initiation time of the discharge electric arc.
• simmer current is obtained from a current generator connected between the two electrodes of the xenon lamp. It aims to maintain the ionization level of the plasma after the formation of the ionization electric arc. Thus, successive electric discharge arcs can be produced while maintaining this simmer current, and therefore without having to generate another ionization electric arc before generating each of the discharge electric arcs.
• this simmer current also makes it possible to limit the ignition delay and to obtain light flashes running at less than 200 nanoseconds.
• the intensity of this simmer current depends directly on the internal diameter of the xenon lamp tube. For example :
• the simmer current is typically between 100 and 300 mA
• the simmer current is generally set close to 700 mA.
• the internal diameter of the tube also has an important influence in determining the light energy generated by the xenon lamp.
• the plasma is particularly hot during this transformation, typically close to 100,000 K and, if this plasma touches the inner edges of the tube, it abrades the inside of the tube and reduces the life of the xenon lamp, even for particularly resistant tubes made of quartz.
• a very high current density in the plasma is sought, and this high density current also leads to an increase in the temperature of the plasma and a risk of abrasion of the internal wall of the tube, and therefore consequently a reduction in the life of the lamp.
• xenon tubes with small internal diameters, typically less than 3 millimeters, for which it has been found that the plasma is naturally placed in the center of the tube. internal diameter of the tube.
• the small internal diameter of the tube limits the light energy generated to achieve the desired germicidal effect.
• the technical problem of the invention is therefore to obtain a light flash generator making it possible to generate a large amount of light energy while ensuring the service life of the tube of the discharge lamp.
• the invention arises from the observation that the problem of abrasion of the internal wall of the tube arises from problems of centering the plasma inside the tube during the formation of the electric discharge arc.
• the plasma is no longer automatically placed in the center of the tube and can move in the vicinity of the internal wall, so that its expansion comes naturally. abrade the quartz constituting the tube.
• the invention proposes to magnetically move the plasma inside the tube before generating the electric discharge arc, so as to place this plasma substantially on the axis of revolution of the tube.
• the invention relates to a light flash generator comprising: a discharge lamp consisting of a hermetic cylindrical tube incorporating xenon, two discharge electrodes sealed respectively at each of the ends of said tube; an ionization electrode; an electrical discharge circuit comprising a high capacity electrical energy storage source, means for charging said electrical energy storage source, and means for discharging this electrical energy storage source between the two electrodes discharging the discharge lamp so as to form a discharge electric arc between the two discharge electrodes; an electrical ionization circuit comprising a low-capacity electrical energy storage source, means for charging this electrical energy storage source, and means for discharging this electrical energy storage source on the ionization electrode so as to form at least one electric ionization arc between the two discharge electrodes and transform the xenon into plasma; and a simmer power supply circuit comprising a current generator connected between the two discharge electrodes of the discharge lamp and configured to generate a current of constant intensity in the discharge lamp and retain the plasma formed by the electric arc d ionization
• the invention is characterized in that the light flash generator also comprises at least one magnetic field generator arranged outside the tube and configured to move the plasma substantially up to the axis of revolution of the tube before the generation of at least one. minus a discharge electric arc; and in that the hermetic tube is made of quartz with an internal diameter of between 7 and 9 millimeters; and in that the light flash generator comprises a supervision member connected to the discharge means of the electric discharge and ionization circuits as well as to the current generator of the simmer supply circuit, the supervision member comprising means for controlling a pseudo -simmer mode in which, before each electric discharge arc, the supervisory unit controls the generation of at least one ionization arc and a displacement of the plasma by means of the at least one generator magnetic field during the application of the simmer current until the plasma is substantially disposed on the axis of revolution of the tube.
• the invention makes it possible to implement a xenon lamp with an internal diameter of the tube greater than 6 millimeters, without requiring any complex cooling device, and using only the convection in the outside ambient air in which is the lamp.
• the duration of the discharge arc can be determined so that the expansion of the plasma does not reach the inner wall of the tube of the discharge lamp.
• the convection in the ambient air can be improved by a forced convection cooling device.
• the invention has two variants, a variant with a simmer mode and a variant with a pscudo-simmer mode.
• the application of one or the other of these two variants is preferably obtained by a supervisory member which controls the discharge means of the electrical discharge and ionization circuits as well as the current generator of the simmer supply circuit. to pace their operations.
• the simmer mode corresponds to maintaining the current for several consecutive discharge electric arcs.
• the displacements of the plasma are produced by a confining magnetic field, preferably obtained by several magnetic field generators regularly arranged around the tube of the xenon lamp.
• the various magnetic field generators form magnetic fields in several radial directions relative to the axis of revolution of the tube so that the plasma is confined substantially on the axis of revolution.
• the pseudo simmer variant aims to use, before each electric discharge arc, an ionization arc and displacement of the plasma by means of the magnetic field generator during the application of the simmer current until the plasma is substantially disposed. on the axis of revolution of the tube.
• the magnetic field generator By knowing the initial location of the plasma, it is possible to arrange the magnetic field generator so that it moves the plasma in a direction perpendicular to the axis of revolution of the tube. When the plasma has traveled long enough for it to reach the axis of revolution of the tube, the electric discharge arc is generated. The simmer current is stopped before or after the generation of this discharge electric arc. Thus, to generate a new electric discharge arc, a new ionization arc and a new displacement of the plasma must be carried out.
• the time required to move the plasma depends on several factors and this time should be estimated on a case-by-case basis to obtain a displacement of the plasma substantially up to the axis of revolution of the tube.
• this displacement time obviously depends on the internal diameter of the tube, but also on the magnetic intensity of the at least one magnetic field generator and the intensity of the simmer current.
• the plasma is also influenced by gravity and tends to rise in the tube as its temperature increases. It is therefore necessary to take into account these various factors to practically determine the magnetic intensity and the time of application of the simmer current necessary to obtain a centering of the plasma.
• the plasma displacement time is between 2 and 20 milliseconds.
• the first two embodiments use ionization by connecting the ionization circuit to a linear electrode external to the lamp, while the third embodiment uses ionization by connecting the ionization circuit to a discharge electrode of the lamp. dump.
• the ionization electrode consists of a conductive electric wire arranged outside the hermetic tube and connected to the electric ionization circuit, the electrically conductive wire extending along the hermetic tube. so as to guide the ionization generated by the electric ionization circuit close to the conductive electric wire.
• This embodiment makes it possible to guide the ionization by the electric radiation produced by the electric wire.
• two independent ionization regions are formed respectively in the tube between the two discharge electrodes and the part of the electric wire closest to each discharge electrode. During the ionization phase, these two ionization regions stretch and come together to eventually form the ionization arc between the two discharge electrodes.
• the ionization electrode consists of a metal strip arranged outside the hermetic tube and connected to the electrical ionization circuit, the metal strip extending along the hermetic tube so in guiding the ionization generated by the electrical ionization circuit close to the conductive metal strip.
• the ionization electrode consists of one of the two discharge electrodes of the discharge lamp connected to the electric ionization circuit, the light flash generator also comprising a metal blade or a wire. electric conductor extending along the hermetic tube and outside the latter so as to guide the ionization generated by the electric ionization circuit near the metal strip or the conductive electric wire.
• the metal blade or the conductive electric wire used in the third embodiment can be connected to an electric voltage reference, for example to ground, or to the discharge electrode which is not connected to the electric ionization circuit. .
• the ionization is formed between the electrode connected to the ionization circuit and the part of the metal blade or the conductive wire closest to this electrode. During the ionization phase, this ionization extends along this metal blade or conductive electric wire until it reaches the second discharge electrode of the discharge lamp and forms the ionization arc.
• this third embodiment with the first or the second embodiment by connecting the ionization circuit both to one of the discharge electrodes and to the metal blade or to the conductive electric wire. .
• This embodiment allows, in certain cases, to modify the formation of the ionization arc.
• the plasma formed by the ionization arc is then moved to reach the axis of revolution of the tube by at least one magnetic field.
• This magnetic field is generated by a permanent magnet or by an electromagnet.
• Figure 1 is a schematic perspective view of a discharge lamp according to a first embodiment of the ionization electrode
• Figure 2 is a schematic representation of a light flash generator incorporating the lamp of Figure 1 according to one embodiment of the invention
• FIGS 3a-3e schematically show five reactions obtained in the discharge lamp of Figure 1 to form a discharge arc according to the invention
• Figure 4 is a schematic sectional representation of the magnetic fields created around the discharge lamp of Figure 1 according to one embodiment of the invention.
• Figure 5 is a schematic perspective view of a discharge lamp integrated in a housing according to a second embodiment of the ionization electrode
• Figures 6a-6b show two schematic sectional views of the housing of Figure 5, with ( Figure 6b) and without ( Figure 6a) the magnetic fields created around the discharge lamp;
• FIG. 7 is a schematic representation of a light flash generator incorporating the lamp of FIG. 5 according to one embodiment of the invention.
• FIGS 8a-8e schematically show five reactions obtained in the discharge lamp of Figure 5 to form a discharge arc according to the invention
• FIG. 9 is a schematic representation of a light flash generator incorporating a discharge lamp according to a third embodiment of the ionization electrode.
• Figures 10-10e schematically show five reactions obtained in the discharge lamp of Figure 9 to form a discharge arc according to the invention.
• FIG. 1 illustrates a discharge lamp 11 formed by a hermetic cylindrical tube 14 incorporating xenon. Inside this tube 14, the discharge lamp 11 comprises two electrodes: an anode 12 and a cathode 13. In addition, a third ionization electrode 16 is formed around the discharge lamp 11 by means of a conductive electric wire disposed along the outer surface of this discharge lamp 11 and held by four loops 23 of this same electric wire 16 wound around the tube 14.
• this discharge lamp 11 can be mounted in a light flash generator 10a according to the invention by using a Cd discharge circuit connected to the two electrodes 12 and 13, said electrodes being sealed to both. tube ends 14.
• This Cd discharge circuit includes a high capacity electrical energy storage source Ch, typically a capacitor with a capacity of between 200uF and 30mF.
• a first terminal of this capacitor Ch is connected to the anode 12 via a switch II and a second terminal of this capacitor Ch is directly connected to the cathode 13.
• this capacitor Ch is also connected to charging means Th, for example a voltage-limited current source I.
• the electrodes 12 and 13 of the tube 14 are also connected to a simmer Cs power supply circuit comprising a constant current generator Gc.
• the constant current applied by the simmer Cs power supply circuit in the discharge lamp 11 is between 100 and 300 milliAmps.
• the electric wire 16 constituting the ionization electrode is connected to an ionization circuit Ci comprising an energy storage source C1, for example a capacitor, the capacity of which is between 47nF and luF.
• an energy storage source C1 for example a capacitor, the capacity of which is between 47nF and luF.
• a first terminal of this capacitor C1 is connected to the electric wire 16 by means of a switch 12 and a second terminal of this capacitor CI is directly connected to the cathode 13.
• this capacitor CI is also connected to means load TI, for example a voltage-limited current source I.
• the light flash generator 10a also includes at least one magnetic field generator 30-36.
• FIG. 2 illustrates a single permanent magnet 30 disposed under the electric wire 16 with a magnetic field configured to push the plasma P inside the tube 14.
• the field generator magnetic 30-36 can work by attracting the plasma P and this magnetic field generator 30-36 can be formed by one or more magnets or electromagnets.
• two permanent magnets 31 and 32 can be arranged under the tube to form a substantially uniform magnetic field across the diameter of tube 14, while using a single magnet, the shape of magnetic field is conventionally hemispherical.
• This light flash generator 10a makes it possible to generate a discharge arc A4 by means of a pseudo simmer mode illustrated in Figures 3a to 3e.
• This pseudo-simmer mode can be controlled by a supervisory unit, not shown, making it possible to control the scheduling of switches II and 12 and the operation of the current generator Gc.
• the supervisory organ may consist of a microcontroller or a microprocessor executing a series of logical instructions.
• an ionization arc A3 is formed between the two electrodes 12 and 13 by means of the discharge of the capacitor C1 on the electric wire 16.
• the ionization can generate two first arcs. A1 and A2 formed between the electrodes 12 and 13 and the internal wall of the tube 14 closest to the electric wire 16, as illustrated in FIG. 3a.
• the first two arcs A1 and A2 move closer to each other.
• a plasma P begins to be formed inside the tube 14 at the level of the wall closest to the electric wire 16.
• the first two arcs A1 and A2 meet to form a single ionization arc A3 between the two electrodes 12 and 13 and this ionization arc A3 extends over the plasma P which remains formed along the internal wall of the tube 14 close to the electric wire 16.
• the simmer Cs power supply circuit is activated to inject a constant current into the tube 14 between the two electrodes 12 and 13.
• This simmer Cs power supply circuit has the effect of maintaining the ionization of the plasma. P and the ionization arc A3 so that, as long as the simmer power supply circuit Cs is activated, the magnetic field generator 30 moves the plasma P and the ionization arc A3 inside the tube 14.
• the power supply circuit simmer Cs is activated so that the plasma P and the ionization arc A3 have time to move from the internal wall of the tube 14 closest to the electric wire 16 to substantially reach the axis of revolution Ar of the tube 14.
• the duration of displacement of the plasma P can be between 2 and 20 milliseconds and the simmer supply circuit Cs is therefore activated during this period before actuating the discharge circuit Cd.
• a discharge arc A4 is formed between the two electrodes 12 and 13, as illustrated in FIG. 3e. This discharge arc A4 is obtained by discharging the capacitor Ch by closing the switch II. The duration of this discharge arc A4 is determined to prevent the expansion of the plasma P from coming into contact with the internal wall of the tube 14 and abrading the internal walls thereof.
• the discharge Tare A4 can be generated for a period of between 100 and 350 microseconds with some of the light contained in the wavelength band 240. at 300 nanometers to obtain a germicidal effect.
• the light flash generator can include several discharge lamps 11.
• FIG. 5 illustrates a generator 10b comprising three juxtaposed discharge lamps, only one of which is shown.
• this embodiment of FIG. 5 also illustrates a variant of formation of the ionization electrode by means of a metal blade 15 connected to a reflector 17.
• This reflector 17 conventionally makes it possible to return the light generated in the direction of from the bottom of a housing 18 integrating the discharge lamp 11 towards an optical window 19, generally formed by a glass plate, mounted above the housing 18.
• the ionization electrode corresponds to the metal plate 15 and the ionization circuit Ci is connected to the reflector 17, itself electrically connected to the metal plate 15. As illustrated in the figures.
• four permanent magnets 33-36 are juxtaposed in grooves made at the bottom of the housing 18 so as to form a substantially rectilinear magnetic field inside the reflector 17 and, more particularly, inside the three lamps. juxtaposed discharge 11.
• the substantially rectilinear magnetic field is also obtained by placing steel plates, not shown, between the permanent magnets 33-36 to channel the magnetic field.
• FIG. 7 illustrates the electrical diagram corresponding to that of FIG. 2.
• the only difference lies in the fact that the ionization circuit Ci is no longer connected to an electric wire 16, but to the metal strip 15 by means of the reflector 17.
• the permanent magnet 30 is replaced by the four permanent magnets 33-36.
• the ionization carried out from this metal strip 15 is identical to that obtained by the metal wire 16, and makes it possible to obtain a similar phenomenon of formation of ionization Tare A3 by passing through two first arcs Al and A2.
• Another possible mode of ionization consists in using a metal plate 15 close to the tube 14 and in connecting the ionization circuit Ci directly to one of the electrodes of the tube 14.
• the generator 10c illustrated in FIG. 9 is obtained by connecting the ionization circuit Ci to the anode 12 of the tube 14, while the metal strip 15 is not connected to any circuit.
• this embodiment differs from the two previous embodiments in that the ionization range A3 is formed by a single first arc A1 which extends along the tube 14 at the level of the wall closest to the metal strip 15 until it reaches the anode 13 of the tube 14.
• the plasma P is always formed in the same place, that is to say at the level of the internal wall of the tube 14 closest to the metal blade 15.
• the plasma P can be moved in an identical manner to the first embodiment concerning the generator 10a until that this plasma P substantially reaches the axis of revolution Ar of the tube 14. It is also possible to carry out the invention by configuring the supervisory unit to operate in simmer mode, that is to say in a mode in which several discharge arcs A4 can be generated successively without having to go through a phase again. for generating an ionization arc A3 and for moving the plasma P. To do this, the invention proposes to use a magnetic field for confining the plasma P by arranging magnetic field generators regularly all around the tube 14.
• the arrangement of the magnetic field generators may correspond to that described in document EP 0209469, in which a confining magnetic field is produced by means of magnets regularly arranged on the circumference of a cylindrical tube.
• the magnetic field generators are constituted by electromagnets, so that only electric wires are arranged around the tube 14 to limit the impact of these magnetic field generators on the light emanating from the lamps. discharge 11.
• a first step therefore consists in generating an ionization arc A3 as described in one of the three preceding embodiments. Following the generation of this ionization arc A3, the simmer power supply circuit Cs is activated and the confining magnetic field drives the plasma P to substantially reach the axis of revolution Ar of the tube 14.
• this embodiment makes it possible to move the plasma P more easily since it is not necessary to estimate the displacement time of the plasma P to reach the axis of revolution Ar and it is possible to wait a period of stabilization of the plasma P.
• the invention makes it possible, for the same lifetime, to form more intense flashes of light with, in particular, greater germinicidal properties.

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Citations (5)

• 2019
  • 2019-11-13 FR FR1912659A patent/FR3103075B1/fr active Active
• 2020
  • 2020-10-30 WO PCT/FR2020/051964 patent/WO2021094666A1/fr unknown
  • 2020-10-30 EP EP20807847.7A patent/EP4059319A1/de not_active Withdrawn

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