EP2686872A1 - Dispositif d'emission de lumiere par le phenomene de cathodoluminescence - Google Patents
Dispositif d'emission de lumiere par le phenomene de cathodoluminescenceInfo
- Publication number
- EP2686872A1 EP2686872A1 EP12708858.1A EP12708858A EP2686872A1 EP 2686872 A1 EP2686872 A1 EP 2686872A1 EP 12708858 A EP12708858 A EP 12708858A EP 2686872 A1 EP2686872 A1 EP 2686872A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- filament
- bulb
- voltage source
- luminescent material
- light
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J63/00—Cathode-ray or electron-stream lamps
- H01J63/02—Details, e.g. electrode, gas filling, shape of vessel
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J63/00—Cathode-ray or electron-stream lamps
- H01J63/06—Lamps with luminescent screen excited by the ray or stream
Definitions
- the invention relates to the technical field of lighting, more precisely lighting devices using the phenomenon of cathodoluminescence.
- the invention can be used in the fields of signaling, indoor and / or outdoor lighting, screen lighting, decoration, etc.
- Incandescent bulbs produce light by heating a filament placed in a vacuum chamber.
- the filament is heated, by application of an electrical voltage at its ends, to a temperature which is close to its melting temperature.
- the light is then emitted by the phenomenon incandescence.
- One of the drawbacks of this technique is the low efficiency between the electrical energy consumed and the light energy produced, this efficiency being less than 10%.
- the rest of the energy is mainly radiated as heat, absorbed in part by the surface of the bulb which can reach several hundred degrees. Because of this low yield, the marketing of this type of bulb is limited, sometimes prohibited, in more and more countries.
- Phosphorescent lamps or compact fluorescent lamps can be seen as an alternative solution. They have a much higher efficiency, about a factor of 4 or even a factor of 6.
- the light is emitted from a phosphorus deposited on the inner walls of a glass tube, excited by electric discharges.
- UV radiation emitted by the gas during its de-excitation, is converted into visible radiation by means of a layer of phosphorescent material present on the inner face of the bulb.
- This technique is not an ideal solution. If the UV waves cross the wall of the bulb, they can be dangerous for the man.
- this type of lamp uses frequency currents that produce electromagnetic waves that can affect the health of users.
- the gas mixture used is a mixture based on mercury vapor which is a compound that is dangerous for the environment as well as for humans. This type of lamp therefore has risks in their use and recycling, for health and the environment.
- LEDs Another interesting alternative seems to be light-emitting diodes or LEDs. They have a performance comparable to phosphorescent lamps and they are less harmful to the environment. However, this is not yet a viable alternative because of their selling price which is superior to compact fluorescent lamps, moreover the rendering of the colors is not optimal, the light is "cold" and it is not quite diffuse.
- Cathodoluminescence consists in producing light by exciting a phosphorescent layer, not via U.V. radiation as for phosphorescence, but by bombarding the layer with electrons.
- the electrons, produced by a source or an electron gun, are accelerated towards the phosphorescent layer by means of an electric field produced with direct current. This current can be modulated in sinusoid or other.
- the electric field is formed between two distant conducting elements: a cathode and an anode.
- the voltage between the cathode and the anode must generally be between 5 kV and 10 kV, which corresponds to the high voltage range.
- cathodoluminescence lies in its low power consumption to produce light, of the order of 1mA at 4mA, for a power of the order of 40 Watts.
- the light output of a standard non-optimized phosphor is currently around 30 lumens / watt, so it is possible to make bulbs that can emit up to 1200 lumens.
- a commercial 11 watt compact fluorescent lamp emits 550 lumens.
- Cathodoluminescent systems are therefore able to deliver light powers comparable to those obtained for current commercial systems.
- the ignition of this type of lamp is instantaneous compared to fluocompact systems that require several seconds.
- Cathodoluminescent light bulbs reproduce, on a smaller scale, the fixtures already used in devices such as television screens, electron microscopes and others.
- the electrons are directed and accelerated, through an electric field, to a phosphorescent layer.
- the electric field is obtained by applying a potential difference between a negatively charged conductive element (cathode) and a positively charged conductive element (anode).
- the cathode is usually placed between the electron source and the anode.
- the anode is placed as close to the phosphorescent layer so that the electrons have the greatest energy during their impact on the layer. For this, the anode may be placed, in a first configuration, closer to the phosphorescent layer, or, in a second configuration, between the phosphorescent layer and the inner wall of the bulb.
- the phosphorescent bulbs are mainly made according to the first configuration.
- a phosphor layer is first deposited on the inner surface of the bulb, then a conductive layer, usually aluminum, is deposited on the phosphorescent layer (see Figure 1 of US2007 / 0262698).
- a disadvantage related to this provision is related to the absorption of electrons by aluminum. It is a major loss factor that must be compensated by an increase in the voltage to allow the electrons to reach the phosphorescent layer.
- a first solution is therefore to deposit a layer of transparent conductive material of the type Indium Tin oxide, ITO, on the inner wall of the bulb.
- a second solution is to deposit the aluminum layer between the wall of the bulb and the phosphor layer, according to the second configuration. This latter alternative has more defects than advantages because the anode then reflects the light into the interior of the bulb. It is for these reasons that the first configuration is orally adopted.
- cathodoluminescence bulbs Another disadvantage with cathodoluminescence bulbs is that the emitted light is directed at a much smaller angle compared to the filament bulbs due to the partial overlap of the bulb surface by the phosphorescent material.
- the objective of the invention is to propose technical solutions that respond to the above problems.
- a device is composed of at least one electrical conductive filament.
- the filament is preferably cylindrical with a diameter of approximately ⁇ or greater than this value.
- the filament is covered by a luminescent material whose thickness is less than 20 ⁇ , preferably the thickness is between ⁇ and 20 ⁇ .
- the filament is connected to the ground of a high-voltage source.
- the high-voltage source is advantageously of sufficiently small dimensions to be insertable into a socket of a bulb or bulb.
- the phosphor coated filament is connected to the high voltage source so as to have the function of an anode.
- This device can then be arranged in the socket of a bulb so that the filament is oriented towards the open portion of the socket.
- the socket is connected to a hermetic enclosure, preferably a bulb-type speaker enclosure.
- the enclosure is totally or partially transparent, in the light emitted by the luminescent material present on the filament.
- a vacuum can then be created and maintained in the hermetic enclosure delimited, for example, by the socket and the enclosure of the bulb.
- the created vacuum is a secondary type vacuum.
- the present application also relates to a method of manufacturing a light emitting device by the phenomenon of cathodoluminescence.
- the manufacturing method is composed of at least one step of covering the surface of an electrically conductive filament.
- the material covering it is a luminescent material, the covering thickness is less than 20 ⁇ , preferably between ⁇ and 20 ⁇ .
- the filament may have a diameter of between ⁇ and 500 ⁇ , preferably between 50 ⁇ and ⁇ .
- the filament can be covered by a cathodo-phoresis technique, a step of which consists of immersing the filament in a bath made from luminescent powder.
- the filament covered with luminescent material can then be connected to the ground of a high-voltage source.
- the high-voltage source can then be placed in a socket of a bulb or bulb, so that the filament is oriented toward the open portion of the socket.
- a sealed enclosure can then be sealed to the socket including the high voltage source and the filament.
- the enclosure is transparent or at least partially transparent to the light emitted by the filament.
- a small type of getter component and generally of circular shape can also be arranged in the enclosure. It is composed of alloy (Barium, Zirconium, Titanium, etc.) evaporable or not, depending on the residual gases to be eliminated.
- a vacuum is then formed in the sealed chamber via an opening.
- the opening is also sealed after making the vacuum in the enclosure so as to maintain the vacuum.
- the vacuum realized is a void of secondary vacuum type.
- the getter once the enclosure is sealed typically by heating the latter at high temperature by any appropriate means.
- the Getter ensures a good vacuum level in the enclosure, which can improve the life of the bulb.
- the present application also relates to a method of using an ampoule, as described above, which emits light by the phenomenon of cathodoluminescence, composed of at least a metal filament covered with a luminescent material, connected to the ground of a high-voltage source.
- One step of the method of use relates to energizing the negative and positive terminals of the high voltage source.
- FIG. 1 represents filaments of different shapes
- FIG. 3A represents a bulb composed of a filament
- FIG. 3B represents the trajectories of the electrons impacting the surface of the phosphorescent layer.
- a first step for producing a cathodoluminescence bulb 200 may consist in producing a filament A ( Figure 1).
- the filament is composed of at least one electrically conductive material so that it can be used as an electrode, preferably as anode.
- the material or materials comprising the filament may be, for example, one or a combination of the following materials: stainless steel, silver, tungsten, carbon.
- the filament is electrically conductive.
- the materials chosen are materials with a high melting temperature, in order to be able to anneal the luminescent material after they have been deposited on the filament. Annealing improves the luminescence properties of the deposited material. This list is not exhaustive.
- the length of the filament may be between 5mm and 10cm, preferably between 2cm and 5cm.
- the section of the wire can be between ⁇ and 500 ⁇ , preferably less than millimeter.
- the shape of the filament is not limited to the following example shapes: rectilinear, serpentine, spiral, arcuate.
- the filament is of rectilinear shape or in an arc.
- the shape of the filament is chosen to attract the largest number of electrons 300 emitted by a source of electrons C and have a distribution that is as homogeneous as possible along the current point of the filament ( Figure 3A).
- the filament can be obtained by cutting, melting, hot metal extrusion pressing or any other technique for producing a filament according to the preceding characteristics.
- a first solution is carried out according to the following steps:
- a second solution B is produced, independently of solution A, by mixing 25 ml of glycerol in 25 ml of ethanol.
- the bath is made according to the following steps:
- the bath is placed in an ultrasonic bath at room temperature, preferably at a temperature of the order of 20 ° C.,
- the deposition of the luminescent material can be carried out on the filament, according to the following steps: - agitation of the bath, containing the luminescent materials intended to cover the filament
- a conductive element is connected to a positive pole of a power supply
- the conductive element and the filament are placed in a deposition beaker, separated by a distance of less than 1 cm,
- the material thickness Y 3 AI 5 O 12 : Ce, on the filament, is then about a few micrometers.
- the thickness varies according to the parameters of the cathodo-phoresis process, such as the applied voltage and the exposure time.
- the thickness, e, of the deposit B is between 5 ⁇ and 50 ⁇ (FIG. 2), so as to obtain the maximum cathodoluminescence efficiency between the incident electrons 300 and the emitted light (see below).
- the optimal zone of interaction between the electrons and the luminescent material is between 5 ⁇ and 20 ⁇ , preferably about ⁇ .
- Luminescent materials that can compose the previous bath can be classified by emission color.
- these materials are in the form of micron-sized powder.
- the red color can be obtained, by the cathodoluminescence phenomenon, from a component or a mixture of the following components: Y 2 0 3 : Eu; YVO 4 : Eu; Y 2 O 2 S: Eu; ZnCdS: Ag; ZnCdS: In; ZnCdS: Ag; In: Sn0 2 ; LaIn0 3 : Eu.
- Obtaining other colors or obtaining a light comprising several colors, such as white light can be obtained from a mixture of the above compounds. This mixture can be made before or during the development of the bath.
- the dosage of each powder makes it possible to adjust the color point of the light emitted by the filament during its operation in the ampoule according to the invention, as well as the color temperature of the light in the CIE chromaticity diagram.
- a filament similar to that made previously can be connected to the ground of a high-voltage source.
- the high voltage source is of sufficiently small size to be placed in a bulb socket 101 or in a bulb (FIG. 3A), as described in WO2010 / 030899.
- the negative terminal of the high-voltage source is connected to a conductive element or electron source C, preferably in the form of a peak and directed towards the filament A covered with luminescent material B (FIG. 3A).
- These two means are separated by a minimum distance of between 1mm and 50mm, preferably between 10mm and 30mm.
- the conductive element emits electrons 300 towards the filament A.
- the electrons are emitted by a cold-type cathode, as used in the tubes. electronic, for example described in "Phosphor handbook, WM Yen, S Shionoya, Yamamoto H, CRC Press".
- the envelope 102 is composed of glass or of a material at least partially transparent to the light emitted by the filament.
- the mounting of the envelope can be achieved by a method already used for mounting incandescent bulbs.
- the invention also relates to a conductive filament device A covered by a luminescent material B, as described above.
- the filament and the high-voltage source are integrated in a lamp socket. It is possible to integrate the high voltage source into the socket of the bulb 101 before electrically connecting or connecting the filament A and / or the electron source to the terminals of the high voltage source.
- the socket may be sealed hermetically in a vacuum envelope 102.
- the electrons 300 move from the negative terminal to the grounded terminal due to the electric potential difference.
- the electrons 300 have an initial velocity which corresponds to the movements, at the atomic scale, that they have in the material of the cathode, for example in tungsten or in carbon. They are then torn off by the electric field existing between the anode and the anode. They are then accelerated in the vacuum of the bulb. Their trajectory depends on the area where they are released into the atmosphere of the bulb.
- the point of impact of the electrons 300, on the surface of the phosphorescent layer B covering the filament A depends on these two parameters: the emission zone of the electrons at the electron source on the filament and the initial velocity electrons before their emission. It is therefore possible to adapt the shape of the electron source C and the filament so that the impacts take place homogeneously or in a localized manner on the surface of the phosphorescent layer B.
- a cylindrical structure for the phosphorus layer B is preferably chosen to promote homogeneous excitation of the phosphor layer by the electrons 300 (FIG. 3B).
- the cylindrical structure is advantageously a cylinder of revolution whose height is greater, preferably much greater than its diameter.
- Light emission over the entire filament surface provides a similar or identical light effect to incandescent bulbs, i.e., multidirectional or near-multidirectional emission of light, thereby promoting the use of light. the bulb by the general public ( Figure 3A and 3B).
- ⁇ represents the angle of incidence of a photon on the B / T interface
- the critical angle 6 C is defined by the following relation:
- the photons of the phosphorescent layer arrive with an angle of incidence equal to or greater than the critical angle, they are not transmitted in the vacuum zone, or internal chamber of the bulb.
- the cylindrical shape of revolution of the phosphor layer provides a higher probability for a photon emitted into the layer, to have an angle of incidence, on the B / T interface, which is less than the critical angle, by compared to previously known configurations.
- This device makes it possible to increase by 50% the luminous efficiency with respect to the planar structures. This increase makes it possible to reach the same level as the best current economic systems, in particular the fluocompact systems.
- the luminous efficiency is all the greater as the radius of the filament is small, preferably of the order or greater than ⁇ .
- the material composing the filament is preferably of optically reflective surface so that the photons emitted inwards are not absorbed but reflected towards the B / T interface.
- a method of using such a bulb, emitting light by the cathodoluminescence phenomenon, and comprising at least one metal filament A coated with a luminescent material may comprise a step of connecting at least one filament to the mass
- a bulb as described above provides a similar or better yield than the best economical compact light sources.
- such a bulb offers an attractive potential in technical and industrial terms.
- the light emitted by the bulb is multidirectional, thus offering more possibilities of use than directional devices such as LEDs or previous bulbs based on the phenomenon of cathodoluminescence.
- the level of vacuum necessary for producing a light bulb is greater than the vacuum level of a light bulb. incandescence, this process is perfectly controlled at the industrial level.
- the method of manufacturing a bulb described above is therefore quickly and easily exploitable from chains of assemblies of incandescent bulbs, currently being shut down or processing in several industrialized countries. It is therefore conceivable to produce this type of bulb at costs ranging between the production of incandescent bulbs and compact fluorescent type bulbs.
- An ampoule according to the invention is safer than compact fluorescent lamps, especially because of the use of a direct current that does not produce electromagnetic waves that can harm the environment.
- the complete lighting of this new bulb is instantaneous, compared to fluocompact systems.
- the structure and composition of the filament, covered with the phosphor layer is made from inexpensive and accessible raw materials such as ZnS and ZnO, for example.
- the choice of components and their mixture allows to obtain light sources whose color rendering index (CRI) and color temperature can be chosen with precision.
Landscapes
- Luminescent Compositions (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR1152193A FR2972847B1 (fr) | 2011-03-17 | 2011-03-17 | Dispositif d'émission de lumière par le phénomène de cathodoluminescence |
PCT/EP2012/054652 WO2012123568A1 (fr) | 2011-03-17 | 2012-03-16 | Dispositif d'emission de lumiere par le phenomene de cathodoluminescence |
Publications (1)
Publication Number | Publication Date |
---|---|
EP2686872A1 true EP2686872A1 (fr) | 2014-01-22 |
Family
ID=43929005
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP12708858.1A Withdrawn EP2686872A1 (fr) | 2011-03-17 | 2012-03-16 | Dispositif d'emission de lumiere par le phenomene de cathodoluminescence |
Country Status (3)
Country | Link |
---|---|
EP (1) | EP2686872A1 (fr) |
FR (1) | FR2972847B1 (fr) |
WO (1) | WO2012123568A1 (fr) |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2263093A (en) * | 1939-07-13 | 1941-11-18 | Harry C Zaun | Fluorescent lamp and coating therefor |
US3906286A (en) * | 1972-11-24 | 1975-09-16 | Nippon Electric Co | Hot-cathode indicator tube for displaying luminescent figures |
JPS531979A (en) * | 1976-06-26 | 1978-01-10 | Shiyounan Ouyou Butsuri Kenkiy | Fluorescent incandescent bulb filament and method for manufacture thereof |
KR950034365A (ko) * | 1994-05-24 | 1995-12-28 | 윌리엄 이. 힐러 | 평판 디스플레이의 애노드 플레이트 및 이의 제조 방법 |
US6570322B1 (en) * | 1999-11-09 | 2003-05-27 | Micron Technology, Inc. | Anode screen for a phosphor display with a plurality of pixel regions defining phosphor layer holes |
US20070262698A1 (en) | 2005-12-16 | 2007-11-15 | Telegen Corporation | Light emitting device and associated methods of manufacture |
WO2010030899A1 (fr) * | 2008-09-12 | 2010-03-18 | Vu1 Corporation | Système et appareil pour éclairage cathodoluminescent |
FR2937180B1 (fr) | 2008-10-15 | 2012-02-03 | Newstep | Tube electronique a cathode froide, son procede de fabrication et son utilisation pour ecran d'affichage. |
-
2011
- 2011-03-17 FR FR1152193A patent/FR2972847B1/fr not_active Expired - Fee Related
-
2012
- 2012-03-16 WO PCT/EP2012/054652 patent/WO2012123568A1/fr active Application Filing
- 2012-03-16 EP EP12708858.1A patent/EP2686872A1/fr not_active Withdrawn
Non-Patent Citations (1)
Title |
---|
See references of WO2012123568A1 * |
Also Published As
Publication number | Publication date |
---|---|
WO2012123568A1 (fr) | 2012-09-20 |
FR2972847B1 (fr) | 2014-02-14 |
FR2972847A1 (fr) | 2012-09-21 |
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