FR2522441A1 - FLUORESCENT LAMP WITH ARC DISCHARGE - Google Patents

Abstract

FLUORESCENT LAMP WITH HIGH PERFORMANCE AND LIFETIME AND GOOD COLOR RENDERING. IT CONTAINS AN ARC TUBE 20, TIGHT TO GAS, TRANSMITTER OF ULTRAVIOLET AND VISIBLE LIGHT, PROVIDED WITH ELECTRODES AT ITS ENDS; AN EXTERNAL BULB 12 WHICH TRANSMITS VISIBLE LIGHT SURROUNDING THE ARC TUBE, INTERNALLY COATED WITH A LUMINOPHORE 14 SENSITIVE TO ULTRAVIOLET LIGHT AND PROVIDED WITH ELECTRIC CONDUCTORS 16 THROUGH IT AND CONNECTED TO THE ELECTRICAL CONDUCTORS OF THE TUBE; AND A VAPORIZABLE DISCHARGE MEDIUM CONSISTING OF A MIXTURE OF MERCURY AND THALLIUM HALOGENIDE PLACED IN THE ARC TUBE. APPLICATION TO FLUORESCENT LAMPS.

Description

The invention relates to fluorescent lamps and, more particularly,

  fluorescent lamps containing a

  inner tube with arc discharge The invention also relates to

  a fluorescence and arc discharge combination lamp whose luminous flux, especially with regard to color, may vary between light emanating from

  the arc and the light emanating from the phosphor.

  Most of today's needs are met by inefficient incandescent lamps.

  incandescence is relatively low, and they are

  in large quantities using technology

  known; but the rising cost of electric power has recently

  changed the economic situation.

  the operating cost of incandescent lamps and their relatively short life expectancy, it can be considered that they are not economic lamps in some cases, especially if they are shielded by high efficiency lamps and long life Different designs and geometries have been studied to ensure the needs of highly efficient lamps with long

lifetime.

  Conventional lamps, with visible radiation formed from a phosphor coating inside a partial vacuum discharge tube, are effective and have a

  long life expectancy; but they do not have the necessary geometry

  for use with conventional fixtures and fixtures. There is a potential replacement lamp, the solenoldal electric field lamp, whose operation is similar to that of a fluorescent lamp, but in which an electronic ballast controls a ferrite core placed in an arc discharge medium, so to form ultraviolet radiation that strikes the phosphor coating of the tube wall, thereby obtaining the radiation

  These lamps are small, compact and with a bal-

  electronic devices can easily replace

  conventional incandescent lamps in most fixtures.

  It is not, however, an arc lamp with a main source of light from an arc discharge; he

  rather a fluorescent lamp whose source of light

  main source is radiation from a luminous material

nophore.

  Another important alternative opportunity -

  incandescent lamps is the HARLAC lamp developed by

  the applicant HARLAC is a trademark of the Com-

  General Electric Company, Cleveland, Ohio This is a lamp whose luminous output is due only to the electromagnetic radiation visible in the discharge tube itself, this tube being surrounded by an outer protective bulb and In the HARLAC lamp, the nominal color spectrum at the output depends only on the elements constituting the arc tube and the operating conditions

in this tube.

  Another recent possibility of replacing incandescent lamps is given by "dumped" discharge lamps; it is a classic fluorescent lamp which

  the discharge tube is folded or configured to define

a long discharge path.

  The patent application US Pat. No. 288,822 describes a compact fluorescent lamp with arc excitation. In this application, the combination of a fluorescent lamp and an arc discharge lamp is described whose configuration, which is very advantageous, makes it possible to isolate physically. and to separate the

  plasma phosphor of the discharge arc itself.

  In particular, this lamp contains silver, rhenium and copper halides to obtain the ultraviolet radiation that is useful. In the present invention, a mixture of thallium and mercury halides is used to produce the luminous flux of an arc tube. whose spectral properties are very different from those obtained with the lamp described in the above application. In the present invention, it is the particular and original spectral properties of the luminous flux of the arc tube which allow its use.

  with certain phosphor materials, so that one can-

  to make a lamp before an excellent rendering of the color.

  It is known, for example, that an arc in thallium iodide

  mercury has a green color of about 535 nanoparticles

  However, a lamp with this color does not

  However, it would not be acceptable to replace a

  The arc in thallium-mercury iodide is therefore not in itself a sufficiently useful material for

lamps of general application.

  In a Reiling article published in the Journal of the Optical Society of America (1964), volume 54, page 532, it is stated, and this has been confirmed by the present invention, that a yield of up to lumens per watt in a thallium / mercury iodide arc tube The light radiation emanating from this discharge is almost entirely around 535 nanometers and is defined by the transition state changes in the thallium atom. The present invention has demonstrated that the luminous flux radiated at 352 and 378 nanometers plus other ultraviolet rays is equal to or greater than

  luminous flux of 535 nanometer green light The invention

  advantage of these other spectral emissions from the

  radiation due to thallium to excite one or more coatings

  luminophores placed on an outer bulb

  the arc tube, which provides the thallium-based radiation flux. This is an original lamp in which comparable arc and phosphor light levels are obtained. conventional fluorescent lamps or corrected mercury lamps

  in color previously used.

  To allow comparison, it will be recalled that

  the most efficient light sources currently available

  nible, are low-pressure sodium discharge lamps that are monochromatic sources operating with efficiencies of the order of 175 lumens per watt. Furthermore, arc discharge lamps in high-pressure sodium have color rendering relatively bad and

  operate at a yield of about 125 lumens per watt.

  Finally, metal-halide mercury arc discharge lamps have a good color rendering and have a yield of up to 110 lumens per watt. Despite the ever-increasing price of electrical energy with fewer requirements As far as color is concerned, an efficient long life lamp remains, nevertheless, highly desirable if it has good color rendering characteristics.

  and calculations concerning the lamp according to the invention

  up to 135 or 140 lumens per watt, with the possibility that further optimization

  as to the temperature and proportions of the materials

  is likely to increase the output up to about lumens per watt Also, although the arc tube of the

  The present invention contains one or more metal halides

  the latter do not react chemically with

  the components of this arc tube, and consequently the

  the invention has the significant advantage of a long duration

of lamp life.

  According to a preferred embodiment of the present invention, an arc discharge fluorescent lamp comprises

  a gas-tight arc tube, an ultra-light

  violet, with electrodes placed at its opposite ends

  The lamp has, moreover, an outer envelope

  surrounding the arc tube and transmitting visible light.

  This envelope has a phosphor coating, and conductive

  In the arc tube there is also a vaporizable discharge medium which is made of a mixture of mercury and thallium halide in one embodiment of the invention.

  recommended, the halide used is thallium iodide.

  In addition, the efficiency of the lamp can be increased by adding sodium iodide to the discharge medium And, for better color rendition of the arc tube flow,

  it is also possible to include in the discharge medium

  some amount of an indium halide such as indium iodide.

  The object of the invention is therefore to improve the efficiency

  with a better translation of the color, into a

  fluorescent arc discharge lamp.

  The invention also relates to the production of a lamp or light source that can replace the conventional incandescent lamp while having a better performance

and a longer life.

  Finally, the subject of the invention is the embodiment

  of a lamp in which one easily obtains a good compromise

  put between the output of the lamp and the characteristics of

rendering of the color.

  The rest of the description refers to the drawings

annexed which represent:

  Figure 1 is a side elevation and sectional view of

  a lamp according to the invention, and

  Figure 2 is a side elevation and sectional view of

  of the arc tube shown in FIG.

  FIG. 1 shows an embodiment of the present invention in which the outer bulb 12 and the arc tube 20 have the shape and general dimensions of the HALARC lamp mentioned above. However, the lamp according to the invention can be given a wide range of dimensions. range of dimensions

and forms.

  The outer bulb or envelope 12 of the lamp 10

  FIG. 1 shows an integral phosphor coating.

  The outer bulb 12 is preferably sealed

  to gases, and it transmits visible light.

  may be attached to the base 17 using a process

classic glass sealing.

  The envelope 12 surrounds an arc tube 20 which is more particularly described with reference to FIG. 2. The arc tube 20 constitutes a source of radiation at specific wavelengths which are generally between 350 and 660 nanometers. operating temperature of the lamp, the arc tube 20 may be relatively hard or relatively soft glass This tube is supported in the bulb 12 by means of rigid electrode conductors 18 and 19 that are

  Figure 1 shows drivers 18 and 19 are electrically powered

  mechanically connected to the drivers 16 who work

  17 In a recommended embodiment, the

  hen 12 has a thick glass base 17 through which the conductors 16 pass and which also serves as a stable support for fixing the arc tube 20 in the bulb 12. As is well known in the art, the conductors 16 consist of or are

  coated with a metallic composition which can be

  to have the glass of the support 17 adhered to

  In this way, guarantee the gastightness of the outer casing.

  As is also known from the art, the

  16 are coupled to an appropriate electronic ballast

  which provides the starting and operating voltage

of the lamp.

  FIG. 2 shows the arc tube 20 which consists of a gas-tight arc tube 22 and a light transmitter, with at each end an electrode 24. Preferably, the arc tube transmits the light which is located in the wavelengths between 350 and 660 nanometers The active ends of the electrodes 24 may constitute enlargements of the rods of the electrode or may take other forms, for example, that of a short spiral winding surrounding the ends of the electrode rods as is conventional in high-intensity discharge lamps To form a gas-tight seal, a portion of the conductors 18

  and 19 is constituted by a metal plate 21 all par-

  specially chosen to form a watertight

  gas and adhesive both with the metal of the electrical conductors

  trode and with the glass of the arc tube The plate 21 is

classically made of molybdenum.

  An important feature of the compliant lamp

  to the invention is the presence, in the arc tube, of a half

  particular vapor discharge location in the lamp

  form in particular the invention, this medium consists of a mixture of mercury and thallium halide such that

  Thallium iodide For example, this medium can be introduced

  in the arc tube 20 in the form of a 30

  thallium hard with a droplet 6 of mercury The spec-

  particular light of this medium is characterized in that

  that it has a strong spectral line at 535 nanometers (read

  It has also been found that this discharge medium also has a high luminous flux radiated at 352 and 378 nanometers, plus other near-ultraviolet radiation, which is equal to or greater than

  those at 535 nanometers.

  according to the invention, a phosphor coating 14 is preferably placed on the bulb 12 in order to obtain a light

  practically "white" Since there is not a single

  wavelength of light complementary to light at 535 na-

  in order to obtain this white light

  controls the use, if one wishes good characteristics

  color rendering, luminophores emitting in the blue region of the spectrum at about 450 nanometers and in the red region at about 610 nanometers A small amount of indium iodide may be additionally or alternatively arc so that the latter itself emits a blue color radiation If one wishes to optimize, not the characteristics of rendering of the color, but the yield

  of the lamp, it is recommended to use a phosphor emitting

  between 560 and 610 nanometers and / or sodium iodide

  as a radiating element of the arc tube.

  According to the invention, the arc tube 20

  therefore also a small amount of mercury,

  me, for example, of the drop 26 placed in this tube

  chosen mercury content is usually sufficient for

  keep a mercury partial vapor pressure of the order of 0.1 to 20 bar at operating temperatures. Furthermore, in the lamp according to the invention, a quantity of thallium halide is added depending on the volume, sufficient to obtain a partial vapor pressure of about 0.0013 to 0.13 bar, which corresponds to operating temperatures of the reservoir being between 500 and 9000 C approximately These amounts are in particular between 0.05 mg / cm 3 and 2 mg / cm 3 of the volume of the arc tube The amount of mercury to be added is chosen so as to obtain a partial mercury vapor pressure of between 0.1

  It is also desirable to

  produce small amounts of argon or other rare gas

  in the arc tube to facilitate the priming of the lamp.

  But these rare gases can be added for other purposes in a quantity depending on the desired function. For argon and as is conventional, steam pressures of

  in the order of 0.0026 to 0.13 bar to improve the characteristics

ticks for priming the lamp.

  In this lamp, it is desirable since

  luminous reflux of the arc has a significant green spectral line

  For good color translation characteristics, provide phosphor coatings on the outer bulb emitting blue radiation at wavelengths of the order of 460 nanometers and red radiation at wave of the order of 610 nanometers

  Therefore, the use of lumino-

  double phores, especially in the case where one does not use

  of indium iodide in the arc tube to obtain the

  In particular, europium doped yttrium vanadate (YVO 4: Eu) is interesting in the compliant lamp.

  to the invention since it emits on 610 nanometers this lumino-

  phore is also used in mercury lamps

  corrected in color But, its excitation spectrum does not cor-

  It does not ideally correspond to the ultraviolet luminous flux of electronic thallium transitions. As a result, other Eu +++ activated phosphors, such as borates, aluminates, silicates and phosphates are also

  desirable as phosphors useful in the present invention.

  Dysprosium activated phosphors also provide radiation in the red and blue regions of the spectrum. However, it should be noted that the ultraviolet radiation of thallium is at a considerably longer wavelength than the mercury resonance radiation at 254 and nanometers. , the quantum loss of the conversion of ultraviolet radiation into visible light, using phosphors, is much less than in the case of mercury, so that we can achieve unusual returns as well

  high than 150 lumens per watt or more.

  During a verification of the basic principles of the invention, a vaporizable medium consisting of

  mercury and thallium iodide.

  110 lumens per watt in the green region of the spectrum.

  It has also been shown by calculation that using europium-doped yttrium vanadate as a phosphor in combination with this arc tube and this ionizable medium gives an additional 25 lumens per watt. the conversion of ultraviolet radiation from the arc tube to 352 and

  378 nanometers in radiation at 610 nanometers emanating from

  minophore These results demonstrate that the lamp according to the invention, as described by this embodiment, has a yield of 135 lumens per watt, while giving a light whose color is only slightly different from the white can be counted , moreover, on a yield of the order of 150 lumens per watt by optimizing the volume of the arc tube,

  the operating temperature and the composition of the con-

tituants.

  In other verifications of the principles of

  vention, an arc tube has been manufactured, the medium of which

  vaporizable charge consisted of mercury, iodine,

  In this tube was measured a yield of 63 lumens per watt due to thallium radiation at 535 nanometers and 56 lumens per watt due to

  sodium radiation at 590 nanometers

  3 lumens per watt was due to the

  radiating between 390 and 510 nanometers The resulting effect of these three constituents of the yield (63 lumens,

  56 lumens and 3 lumens per watt) leads to overall efficiency

  This figure has been confirmed by measurement. Thus, without mentioning the possible contributions in the ultraviolet region, it can be considered that the arc tube of the lamp according to the invention provides, by itself, a yield of the order of 120 lumens per watt But, for a correct rendering of the color, it is generally desirable

  to use one or more radiation-sensitive phosphors

  ultraviolet thallium between 350 and 390 nanometers, in order to reform visible radiation at around 610 nanometers and obtain a red coloring balancing Calculations demonstrate that under these conditions, a coating

  phosphor may have a contribution of 20 lumens

  per watt, which gives the lamp a

  140 lumens per watt, with good

  color rendering, and with the possibility of wearing,

252244 1

  by optimization, this efficiency at 150 lumens per watt.

  From the foregoing, it can be deduced that the invention makes it possible to obtain a lamp with high efficiency and long life

  of life, which can replace the conventional incandescent lamp.

  It can be seen, moreover, that the constituents of the arc tube can be chosen, within specific ranges, to provide the possibility of choosing a compromise between the yield and a better rendering of the color. in addition, that the lamp according to the invention is original,

  since it is a combined lamp with arc tube and fluorescent

  rescence, combining the best characteristics of each type, and in which the phosphor material is isolated from the arc discharge. There is therefore a wide range for the choice of phosphor materials usable on the outer bulb, and eliminates, moreover, any possibility of reaction between the phosphor and the arc tube itself Finally, although in the lamp according to the invention, a

  metal halides, these halides do not

  do not chemically lie with the components of the arc tube, and

  therefore an exceptionally long lamp is obtained

nelle.

  It is understood that the foregoing description

  has been made as a non-limitative example, and that

  can be envisaged without, for that, to leave the

  the scope of the invention and the appended claims.

Claims (5)

  1 Fluorescent arc discharge lamp, character- in that it includes   a gas-tight arc tube (20,22) transmits   an ultraviolet and visible light source provided with electrodes (24) at each end thereof;   an outer bulb (12) transmitting light   visible bulb surrounding the arc tube (22), this bulb carrying at least one phosphor coating (14) sensitive to ultraviolet light, and being provided with electrical conductors (16) which pass therethrough and are connected (18, 19) to electrodes of the arc tube, and a vaporizable discharge medium placed in the arc tube, which medium is a mixture of mercury (26) and thallium halide (30).   Lamp according to Claim 1, characterized in that   that the halide is thallium iodide.   3 lamp according to claim 1, characterized in that the discharge medium contains, in addition, iodide sodium.   4 lamp according to claim 1, characterized in that the phosphor contains europium doped yttrium vanadate. Lamp according to Claim 1, characterized in that the luminophore contains a luminophore chosen from the group of borates, aluminates, silicate and phosphate doped with europium. 6 lamp according to claim 1, characterized in   the phosphor contains a dyspro- doped phosphor sium.   A lamp according to claim 1, characterized in that the discharge medium further contains indium iodide.