EP0722617A1

EP0722617A1 - Microwave lamp

Info

Publication number: EP0722617A1
Application number: EP95929809A
Authority: EP
Inventors: Janusz Teklak; Ingo Susemihl
Original assignee: Siemens AG
Current assignee: Osram SBT GmbH
Priority date: 1994-08-09
Filing date: 1995-08-07
Publication date: 1996-07-24
Anticipated expiration: 2015-08-07
Also published as: EP0722617B1; EP0696705A1; ATE144606T1; WO1996005609A1; DE59501128D1; DE59400919D1; ATE161359T1; EP0696705B1

Abstract

<P>The lighting unit has a main reflector (1) formed from two identical reflector shells (11,2) that are located symmetrically about a centre axis (2). Located within the main reflector is an auxiliary reflector unit (4) that has a pair of surfaces (41,42). The lighting tube (5) is positioned between the surfaces. The auxiliary reflector arrangement and the lighting tube can be moved vertically (6) to vary the effect. The auxiliary reflector provides an indirect lighting effect.

Description

description

Mi rowellen lamp

The invention relates to a microwave lamp according to the preamble of claim 1.

A microwave lamp of this type is known from publications, e.g. B. from "The Washington Post", October 26, 1994, p. A3. In this type of lamp, in a manner known per se, microwave energy generated by a microwave generator is used to excite a mixture of an inert gas and sulfur particles enclosed in a quartz glass ball for plasma formation. In this state, due to the sulfur content, this plasma emits radiation which, in the visible region of the spectrum, has a spectral distribution close to that of sunlight, a first property of this type of lamp which is essential for lighting applications. Another of its advantageous properties is that, because of the type of energy conversion from electromagnetic radiation into visible radiation, no electrodes are required in the illuminant, the failure of which in the case of incandescent or fluorescent lamps is known to be one of the causes of a limited service life. Another

The advantage of this type of lamp is the high efficiency with which the energy supplied to the microwave generator is converted into visible radiation. This property means that a microwave lamp forms a radiation-intensive light source, which is also used in particular as a light source for high-performance lights, eg. B. is suitable for spotlights or headlights.

The unrestricted use of this type of lamp, especially with such luminaires, however, is a disadvantage. In order to excite the filling of the quartz glass ball sufficiently energetically, it is not only necessary to use a microwave rators, but also a microwave resonator in order to concentrate the microwave radiation in the quartz glass sphere. In the present application of microwave technology, this microwave resonator must on the one hand have the best possible reflection properties for microwave radiation, but on the other hand must transmit as losslessly as possible in the range of visible light. The microwave resonator is therefore designed as a filigree metal wire cage surrounding the quartz glass ball at such a distance that it is not attacked by the plasma in the quartz glass ball, which also emits infrared radiation. Since it should at the same time be as transparent as possible to light radiation, the thinnest possible metal wire is used. The microwave resonator is therefore mechanically sensitive. Changes in shape caused by mechanical action can, however, change its resonator property. In addition, a contactor must also be ensured so that no microwave energy can be emitted as scattered radiation from the resonator chamber. A piston made of a transparent material must therefore be arranged around the microwave resonator, similar to an incandescent lamp. Because of the system-related properties of a microwave lamp, it is not possible to geometrically place a reflector surface of a luminaire for light control as close to the light source as would be desirable in order to limit the radiation angle of the luminaire with relatively small reflector dimensions zen that there is a narrow bundle of light, as is required in particular for headlights or spotlights, without additional optical, lenses and the like are used for the deflection of the emitted light.

The present invention is therefore based on the object of further developing a microwave lamp of the type mentioned at the outset with simple means in such a way that it can also be used more flexibly and more flexibly than previously possible for lights with narrowly concentrated light emission. In a microwave lamp of the type mentioned, this object is achieved according to the invention with the features described in the characterizing part of patent claim 1.

Without such an additional reflector arrangement, the microwave lamp essentially has the rotationally symmetrical light distribution of a point light source, apart from scatter radiation caused by the microwave generator, but in particular also the microwave resonator. The reflector arrangement surrounding the burner, however, forms an element that does not disturb the propagation of the microwaves, but instead reflects radiation in the visible range of the electromagnetic spectrum, and thus bundles this visible radiation transverse to the lamp symmetry axis. If, according to one of the developments of the invention, this reflector arrangement is designed to be rotationally symmetrical with respect to the lamp symmetry axis, then such a reflector arrangement results - in a plane containing the lamp symmetry axis - in a mirror-image symmetrical, butterfly-like light distribution characteristic with respect to this axis. For a wide range of applications of this type of lamp, which can also be used wherever powerful light sources are required, this radiation characteristic is of indisputable advantage because it enables this property to be used to equip luminaires without excessive scattered radiation Favorable geometrical dimensions have a narrowly radiating, concentrated light emission, without the need for a great deal of optical aids in the luminaire itself in order to achieve the desired light distribution characteristic.

From a technological point of view, the solution according to the invention can be implemented using conventional means which are completely mastered in light and microwave technology. Metallic mirror materials usually used predominantly in lighting technology cannot, of course, be used for this reflector arrangement. They would, at least in part inside the Microwave resonator arranged, overheated during lamp operation, thereby destroyed and probably also affecting the microwave resonator itself. This is different with materials such as quartz glass or mica with suitable dielectric layers. As is known per se, these are insensitive to radiation in the microwave range, but can be arranged relative to the burner of the microwave lamp and configured geometrically such that they act as mirror surfaces with respect to the optical radiation emitted by the burner.

Further advantages or advantageous refinements of the invention result from exemplary embodiments which are described in more detail below with reference to the drawing. This shows:

FIG. 1 shows schematically the construction of a microwave lamp in a known embodiment in connection with a luminaire reflector,

FIG. 2 shows a microwave lamp designed according to the invention, in which, in comparison to the embodiment according to FIG. 1, a reflector arrangement is additionally integrated in the lamp,

FIG. 3 shows a light distribution characteristic of the microwave lamp according to FIGS. 2 and

FIGS. 4 to 7 each show an example of different configurations of the reflector arrangement integrated in the microwave lamp and their practical applications in luminaires with different light emission characteristics.

A lamp reflector 1 with reflector shells 11, 12 is shown schematically in broken lines in FIG. 1, which are arranged in mirror image symmetry to an axis of symmetry 2, in many cases this lamp reflector 1 is rotationally symmetrical. Its outer edge forms the light outlet opening 3 of the lamp. The known embodiment of a microwave lamp 5 is used in this lamp reflector 1, which is shown for reasons of clarity. Radiation energy in the microwave range is generated in a microwave generator 50, which is fed by AC mains voltage, and is radiated into the interior of a microwave resonator 51. As is quite common in microwave technology, a resonance oscillation in the form of a standing wave is formed with the aid of this microwave resonator 51, so that the radiation energy can be optimally used. In the area of an oscillation maximum of this microwave oscillation, a burner 52 is arranged, which is preferably spherical and encloses a cavity in which an inert gas, e.g. B. argon mixed with portions of a material which emits visible radiation in the excited state, is included. In the known microwave lamp 5, this material is pure sulfur. With this mixture of materials, it has been found in the known microwave lamp 5 that a plasma forms in the cavity of the burner 52 under the effect of the microwave radiation, the radiation spectrum of which correlates well with the radiation sensitivity of the human eye. This means that the light emitted by this light source appears very natural to humans.

The microwave resonator 51 must fulfill a double function in the application of the microwave lamp 5. He must concentrate the microwave radiation on the burner 52 in such a way that the required plasma is formed inside it with a high degree of efficiency, ie the microwave resonator 51 must be impermeable to microwave radiation. On the other hand, however, it should transmit the visible radiation emitted in its interior by the burner 52 as freely as possible to the outside. For this reason, it consists of a filigree metal wire cage which is correspondingly sensitive to mechanical influences. For this reason and also for reasons of radiation safety, protection against accidental contact is required, which, similar to an incandescent lamp, consists of an optically translucent lamp bulb 53.

This system-related construction of a microwave lamp is relatively voluminous compared to other conventional high-performance lamps, primarily because of the geometric dimensions of the microwave resonator 51, although the light source itself, ie. H. the burner 52 is quite concentrated. As schematically indicated in FIG. 1, the consequence of this is that, regardless of the individual design of the luminaire reflector 1, its parts near the lamp cannot be brought so directly to the burner 52 emitting the light radiation in order to use the light-directing properties alone the luminaire reflector 1 or its reflector surfaces 11 or 12 to achieve a luminaire with a narrowly focused light distribution characteristic. In FIG. 1, this is indicated by the large radiation angle α, which is thus geometrically determined.

On the one hand, there is therefore a powerful light source in the form of the known microwave lamp 5, which is also particularly suitable for applications in the case of spotlights or headlights, ie. H. luminaires with an extremely concentrated light distribution are suitable. On the other hand, however, suitable light-directing means, that is to say reflectors of a luminaire, cannot be brought close enough to the burner 52 of the microwave lamp 5 which is essentially to be regarded as a point light source. For the bundling of the light emitted by a luminaire, additional light-directing means, such as lenses or diaphragms, must therefore be used in the known structure of the microwave lamp 5, which increases the flexibility for the use of a microwave lamp in a wide spectrum of luminaires restricted.

FIG. 2 shows another embodiment of a microwave lamp 5 with which these disadvantages are eliminated. Here is a lamp reflector in this figure For the sake of clarity, this is omitted and thus clarifies that the illustration in FIG. 2 relates only to the microwave lamp 5 itself. In principle, the structure of the microwave lamp 5 initially corresponds to the embodiment described with reference to FIG. 1. Corresponding elements are therefore also designated with the same reference symbols. They therefore do not need to be repeated here either.

The main difference from the known embodiment of the microwave lamp 5 described with reference to FIG. 1 is that a reflector arrangement 4 is additionally provided directly near the burner 52 and consists of mirror surfaces 41, 42 which are on both sides of a focal plane 43 are arranged. This focal plane 43 cuts through the burner 52 centrally and lies vertically and transversely to the axis of symmetry 2 of the lamp. In this example, the mirror surfaces 41 and 42 are designed in the contour as conical cutting lines, but could also have other contours as long as they open out in a funnel shape. The mirror surfaces 41, 42 can be fixed together with the burner 52 in the interior of the resonator chamber. It is also essential that the material from which they are made is selected with regard to their function. The mirror surfaces 41, 42 should absorb as little energy as possible in the area of the microwave radiation. In addition, they should affect the wave propagation of the microwave radiation in the interior of the microwave resonator 51 as little as possible, and their degree of transmission in this area of the radiation spectrum should therefore be as high as possible. On the other hand, however, their degree of reflection should also be as high as possible in the range of visible radiation so that they can be used as light-directing means. Materials that meet these requirements include quartz glass or mica with corresponding dielectric properties. This reflector arrangement 4, which is fixed near the burner 52, is therefore preferably located in the interior of the microwave resonator 51 and is therefore integrated into the microwave lamp 5 itself. As shown in FIG. 3 in the diagram of a light distribution curve, it causes the visible radiation emitted by the burner 52 to be deflected with a main beam direction transverse to the axis of symmetry 2 of the microwave lamp 5 ¬ equipped microwave lamp 5, the radiation of each direct portion of the emitted by the burner 52

Exclude radiation practically completely. Furthermore, the bundling of the radiation emitted by the burner 52 enables a relatively simple light control at the light reflector 1. Finally, the light reflector 1 can be designed with all its flexibility with regard to its light-directing function in such a way that all the light emitted by a light is maximal two reflections is emitted. In the embodiment of the microwave lamp 5, in which such a reflector arrangement 4 is integrated, it is therefore of only minor importance that the microwave lamp 5 as such and due to the technology used, in its overall dimensions in relation to that The size of the burner 52 is relatively voluminous. This eliminates a major obstacle that previously prevented the use of a microwave lamp in a wide range of applications.

In the following, some examples will show how a microwave lamp 5 of the type described above can be designed particularly expediently and can also be used with different types of luminaires. Since in these examples above all the different light distributions of luminaires to be achieved with the aid of the reflector arrangement 4 in combination with luminaire reflectors 1 or their reflector surfaces 11, 12 are to be demonstrated, the microwave lamp 5 itself is no longer shown completely in the following figures. but just to clarify it as almost punctiform light source shown burner in connection with the surrounding reflector arrangement 4. In order to clarify the lighting principle, these representations do not use scale scales, but the person skilled in the art knows how to choose the appropriate lighting parameters in the individual application using his lighting technology knowledge in order to optimize the lighting shapes to solve his individual problems Task to arrive.

The lamp shown schematically in FIG. 4 in a cross section has a lamp reflector 1 with reflector shells 11 and 12, the outer edges of which delimit the light exit opening 3 in a plane perpendicular to the axis of symmetry 2. In the interior of the main reflector 1, only the burner 52 and the reflector arrangement 4 of the microwave lamp are shown in a simplified manner. The mirror surfaces 41 and 42 of this reflector arrangement 4 are also formed in this example in the contour as conic section lines. In this embodiment, these are mutually penetrating parabolas, the penetration points of which lie in the axis of symmetry 2, the center of the burner 52 being arranged at the focal point of these parabolas.

A double arrow 6 indicates schematically that the microwave lamp 5 — here the reflector arrangement 4 — together with the burner 52 can be arranged displaceably along the axis of symmetry 2 with respect to the lamp reflector 1. In this way, it is possible to change the light distribution characteristic of the luminaire with one and the same configuration of the luminaire reflector 1, as will be shown in more detail below. Furthermore, in order to explain the lighting function of this lamp arrangement, various light beams 71 and 72 are shown in FIG. 4 by way of example. In the case of the light rays 71, these are light rays of the first type, namely light rays that emanate from the

Burner 52 starting directly from the lamp reflector 1, in the example the reflector shell 11, and from there emerge from the luminaire after only one reflection through the light exit opening 3. The light beams 72 represent light beams of the second type which - in relation to the focal plane 43 - emerge from the burner 52 at higher beam angles. These light beams are initially simply reflected on one of the mirror surfaces 41 or 42 of the reflector arrangement 4 and only then strike the lamp reflector 1, here the reflector shell 12, so that after a total of two reflections through the light exit opening 3 of the reflector assembly 12 Exit lamp.

These examples of the beam path illustrate that the light emerging from the burner 52 is preferably deflected in a direction transverse to the axis of symmetry 2 by the funnel-shaped configuration of the reflector arrangement 4, wherein it is reflected a maximum of once before striking the lamp reflector 1 . With a corresponding design of the reflector shells 11 and 12, all the light emitted by the burner 52 is reflected at most twice before it passes through the light exit opening 3. The cross-sectional shape of the mirror surfaces 41 and 42 of the reflector arrangement 4 created by the penetration of the parabolas ensures that no light can be reflected back into the burner 52 itself.

FIG. 5 uses a further example to explain the design options that can be achieved with this design principle of a microwave lamp 5. In comparison to the embodiments described above, identical or comparable elements are again identified by the same reference numerals, so that repetitions of the description can be avoided. In this exemplary embodiment, the contours of the mirror surfaces 41 and 42 of the reflector arrangement 4 are designed as interpenetrating ellipses, the interpenetration points of these conic sections also lying on the axis of symmetry 2 here. In adaptation to this configuration of the reflector arrangement 4, the two reflector shells 11 are here or 12 of the lamp reflector 1 pulled apart a little further. This luminaire shape, in particular, results in a rather narrow light distribution characteristic and is relatively flatter than the luminaire shape according to FIG. 4.

A further possible embodiment is shown in FIG. 6. This example is intended to demonstrate that there are further design options available for the mirror surfaces 41 and 42 of the reflector arrangement 4 of the microwave lamp 5, while maintaining the lighting principle. In the above-described embodiments, the mirror surfaces 41, 42 of the reflector arrangement 4 are of mirror-symmetrical design with respect to the focal plane 43, whereas the mirror surfaces 41 and 42 according to the embodiment of FIG. 6 each have a completely different contour. Only the symmetry of the reflector arrangement 4 with respect to the axis of symmetry 2 and the symmetry of the luminaire reflector 1 with respect to this axis are retained. This example with a mirror surface 41 of approximately hyperbolic contour and a roof-shaped mirror surface 42 composed of straight sections demonstrates possibilities for the configuration of the reflector arrangement 4 with regard to the geometry of the burner 52, whereby it can be stated only in a restrictive manner that the mirror surfaces 41 and 42 open outward in a funnel shape with respect to the focal plane 43 and should form a clear reversal point at the intersection with the symmetry plane 2, so that retroreflection of the light emitted by the burner 52 is avoided in the latter.

FIG. 7 shows the embodiment described with reference to FIG. 6 again. The two representations of FIGS. 6 and 7 are intended to show, in comparison to one another, how the distribution of the light emitted through the light exit opening 3 changes when the position of the light emitted by the reflector arrangement 4 and the burner 52 is schematically illustrated. striated microwave lamp 5 changes by a longitudinal movement in the direction of the axis of symmetry 2. In FIG. 7, the reflector arrangement 4 together with the burner 52 is shown drawn deeper into the lamp reflector 1, ie it is at a greater distance from the light exit surface 3 with respect to the same lamp reflector 1. This change in position in the direction of the arrow 6 '( According to FIG. 7), the radiation characteristic of the luminaire changes due to the conical contour of the reflector shells 11 and 12 of the luminaire reflector 1. While according to FIG. 6 there is a more broadly radiating characteristic, the radiation characteristic is according to the arrangement Figure 7 preferably narrow beam.

The embodiments explained above for lamps equipped with a microwave lamp 5 illustrate a wide range of applications for this powerful lamp when it is additionally equipped with a reflector arrangement 4 integrated into the lamp. There are quite different possible solutions for the design of this reflector arrangement 4 in order to achieve the desired light control, in particular in a material-appropriate manner and adapted to the geometry of the burner 52 of the microwave lamp 5. The luminaire manufacturer is thus provided with a light source that can be used expediently and with a high degree of efficiency in a wide range of applications.

Claims

claims

1. Microwave lamp with a microwave generator (50) for generating microwave radiation, a microwave resonator (51) formed from a metal wire cage for bundling this microwave radiation and with a closed burner (52) arranged inside the microwave generator, filled with an inert gas and a radiation-emitting element which is visible in the excited energy state, characterized in that the burner (52) surrounds an optically effective microwave beam which extends outwards and extends vertically and transversely to an axis of symmetry (2) of the microwave resonator (51) and which opens outward from the burner (52) on the other hand, a transmitting reflector arrangement (4) is provided.

2. Microwave lamp according to claim 1, dadurchge ¬ indicates that the reflector arrangement (4) is roof-shaped, has optical mirror surfaces (41 and 42) which - viewed in cross section - each have the Bren¬ ner (52) facing roof surfaces and a flat or have a contour designed as a conic section line.

3. The microwave lamp as claimed in claim 2, so that the reflector arrangement (4) is designed to be rotationally symmetrical with respect to the axis of symmetry (2).

4. Microwave lamp according to claim 2 or 3, characterized in that the mirror surfaces (41 or 42) of the reflector arrangement (4) are formed as conical surfaces which penetrate each other in the axis of symmetry (2) and in their perpendicularly aligned focal point ¬ point level (43) of the burner (52) is arranged.

5. microwave lamp according to one of claims 1 to 4, since - characterized in that the reflector arrangement (4) is arranged entirely within the microwave resonator (51)

6. Microwave lamp according to one of claims 1 to 4, d a ¬ d u r c h g e k e n n z e i c h n e t that the reflector arrangement (4) is formed laterally by the microwave resonator (51) sufficiently.

7. Microwave lamp according to one of claims 1 to 6, d a ¬ d u r c h g e k e n n z e i c h n e t that the reflector arrangement (4), mechanically connected to the burner (52), is fixed inside the microwave resonator (51).