IE46352B1 - Lamp - Google Patents

Description

The invention relates to a lamp or flashlight (especially a tail light, safety lamp or signal lamp) having a light source, a main reflector and an assistant or auxiliary reflector disposed co-axially to one another and having different parameters and different focal regions.

Such a lamp has become known heretofore from French Patent No. 747,832 to Fraise. In this heretofore known lamp, at least two separate light sources are provided and selectively switched on; these separate light sources selectively produce a parallel bright light such as a driving light or, on a weakly diffused, illuminated background, a ring-shaped light beam which forms such a sharp contrast with respect to the background that the illumination is very ill-suited for identifying objects. This heretofore known lamp is especially inadequate for meeting the herein15 after explained requirements of signal lamps or the like.

The light beam of.a signal lamp or the like should (for example, according to the German code of regulations) at least illuminate an angular spread or angle range having a square cross section which extends 10° toward the right-hand side and 10° toward the left-hand side of the direction of travel. In order to attain such an aperture angle of, respectively, 20° in vertical and in horizontal directions, the aperture angle of a light beam axially symmetrical to the travel direction must be at least about 28°. 6 3 5 2 In the past, one proceeded from the assumption that the light intensity (measured in candle power) should be as uniform as possible in this light beam. If the energy available for operation of the lamp is limited, however, which is the case, for example, for bicycles or for parking lights of motor vehicles (which also ought not to drain the battery when parking for a long time), it is thus more expedient to distribute the light intensities non-uniformly following a general pattern.

This is explained by means of an example. A bicyclist travels on a two-lane street or road having a width of 8m. and is located a distance of 1 ffl. from the side of the road. The difference in velocity between the bicyclist and a passenger car following behind him is generally very great, especially along straight stretches of rosd if, for example, the bicyclist is travelling at 15 km per hour and the motor vehicle at 100 km per hour. Because of this great velocity difference, bicyclist is generally overtaken more rapidly by the motor vehicle following behind him than is a motor vehicle preceding such a following motor vehicle, so that actually the rear or tail light of the bicycle must be visible better and farther than that of a motor vehicle. Since, however, less energy is available to the bicyclist than to a motor vehicle, the latter has been provided with a stronger, i.e. more powerful, tail light in accordance with the prior state of the art. It Should be taken into consideration that the motor vehicle approaching from behind the bicycle often travels so that the driver of the motor vehicle is located in the middle of the road. In this case, the line of sight from the eye of the driver of the following motor vehicle to the tail light of the bicycle, with the direction of travel, includes an angle referred to hereinafter as the “viewing angle11. This viewing angle increases as the motor vehicle overtakes the bicycle. In order for the tail light of the bicycle to be visible in the respective viewing angle, a) in an axially symmetrical aperture angle of the tail light the aperture angle must be / twice as large as the respective viewing angle, b) the intensity of the lighting power must be adequate for perceiving the light or lamp.

For example, if the tail light of the bicycle is visible to the driver of the approaching motor vehicle up to a distance of 170 m. within a viewing angle of up to 2°, the axially symmetrical aperture angle of the light beam that remains perceivable within this range of distance must be 4°. In the range of distance from 170 m. to 70 m,, the viewing angle is from 2° to 5°, so that the axially symmetrical aperture angle of the light beam visible in this range of distance must be from 4° to 10°. In a range of distance from 70 m. to 17m., the viewing angle is from 5° to 10°, so that the axially symmetrical aperture angle of the light beam visible in this range of distance must be from 10° to 20°.

Since the visibility of a conventional lamp decreases with the distance therefrom, however, the lighting power or light intensity of the beam must correspondingly increase from the outside toward the inside thereof in order to ensure uniform visibility of the lamp or light independently of the distance. For example, the range of the light beam of the lamp or light, which is visible to the following motor vehicle at a distance of 170 m. and more, should shine or illuminate more intensely than, the range which the eye of the approaching driver meets as he approaches, for example, to 17 m.

Naturally, other factors are involved, such as, for example, the curvature of the road, varying road widths, varying travelling conditions, if on-coming or two-way traffic exists or not, and the like. tven after taking these factors into consideration, it remains advantageous to construct a lamp so that it, in addition to a basic brightness which ought not to be diminished anywhere within the light beam, additionally processes a brightness increasing toward the axis thereof.

In order to increase the brightness sharply especially in the viewing directions necessary for great distances, only relatively slight amounts of light are required, because the closer the viewing direction is to the axis, the smaller is the solid angle to be illuminated and the lower is the amount of light necessary for increasing the lighting power or light intensity.

The foregoing remarks may be summarized to the effect that, with regard to a single lamp, it is an object of the invention to provide such a lamp having low energy consumption, a) which is clearly visible by other travellers on the road even at a great distance, and b) which remains visible by these other travellers on the road even when they approach outside or beyond the axis of the lamp of light.

This objective is attained with a lamp such as is described in my presently allowed co-pending United States Patent Application Serial No. 808728, filed 21 June 1977 and, for example, in viewing directions which include, with the travel direction, a viewing angle of 46332 °, 2.5° and 1°, respectively, two, three and fives times, respectively, the lighting power or light intensity as in viewing directions which include a viewing angle of 10° with the travel direction. These values should obviously not change abruptly, but rather, should continuously merge increasingly into one another.

It has been found, however, that the basic brightness of the lamp of my hereinbefore-mentioned co-pending United States Patent Application could be improved. With respect to the lamp of my aforementioned co-pending United States Patent Application, it is an object of the instant application to provide a lamp wherein the light in a range of 10° (viewing angle) to the axis up to at least 15° (viewing angle) to the axis is intensified to such an extent that the light distribution curve in this range has a bulge. In this manner, the visibility of the lamp in directions deviating from the axial direction should be sharply increased.

According to the invention there is provided a lamp having a main and an assistant reflector disposed mutually coaxially and having different parameters and different focal regions, said different focal regions being located within said common axis and having a distance from each other, said lamp comprising a light source disposed at least adjacent the focus of the assistant reflector so that the main reflector emits a hollow light beam, and means associated with the assistant reflector for diverting light of the assistant reflectoy into a solidly conical light beam whose aperture angle corresponds to that of the hollow light beam of the main reflector to such an extent that both said hollow and solidly conical light beams exhibit at least one of the characteristics of supplementing and overlapping one another. 463 63 This lamp according to the invention has a light distribution curve composed of two parts: a) The range of high lighting power or light intensifies located near the axis is formed of the solidly conical light beam radiating from the assistant reflector; this range corresponds to the light distribution curve of my aforementioned co-pending United States Patent Application; b) The bulges on both sides of the light distribution curve, respectively, between 10° (viewing angle)to the axis, are formed by the ring-shaped (hollow) light beam and/or by overlapping of both light beams.

In accordance with an optical feature of the invention, the means for diverting the light of the assistant reflector, comprise protuberances in the form of a plurality of at least one type of structural features selected from the group thereof consisting of bulges and depressions formed in the reflecting surface of the assistant reflector, all of the protuberances having a mean height that is 32 to 202 of a mean smallest base diameter of all of the protuberances, a maximal spacing between two points of the light source being at least twice as large as the mean height of all of the protuberances.

In accordance with a further optical feature of the invention and instead of this special construction of the reflecting surface of the assistant reflector or in addition to this construction of the reflective surface of the assistant reflector, the means for diverting the light of the assistant reflector comprise flutes formed in a cover plate located at a light outlet end of the reflectors, the flutes being in a region of the cover plate through which the light of the assistant reflector passes.

If the light sources is located in the focal region of the assistant reflector, a result thereof is that the main reflector emits the ringshaped (hollow conical) light beam which alone or primarily produces the bulges of the Tight distribution curve. Should these bulges be shifted closer to the axis of the lamp or should the amount of light contained in these bulges be directed fully parallel, not only is the aforementioned possibility provided advantageously, that the light source be disposed in the focal region of the assistant reflector, but rather, moreover, the further possibility is afforded of shifting this light source into the focal region of the main reflector.

In accordance with an added optional feature of the invention, the light source, on the one hand, and the reflectors, on the other hand, are adjustably shiftable in axial direction relative to one another so that the light source is selectively disposable in either of the focal regions, the light source, when in the focal region of the main reflector emitting a substantially parallel main light beam.

A lamp with the given shifting or adjusting possibility is suited, for example, as building-site lamp. - The lamp distribution is variable so that this building-site lamp, selectively, (for example, on straight stretches of a limited access highway) is already visible from a great distance or (for example, on highways having many curves) is also visble from the side within a given viewing angle, depending upon whether the light source is set in the one or the other reflector.

Also, it is possible, with such a lamp, as desired, to shine a parallel light beam into the distance or, when adjusting or setting the light source in the focal region of the assistant reflector, to illuminate a great area 46382 close at hand. Thus, the lamp according to the invention can be employed not only as a signal lamp, but also, for example, as a flashlight.

The light-diverting means associated with the assistant reflector, should not be dulled or deadened because, when the surface thereof is dulled or deadened, it would scatter the light uncontrollably in all directions. In accordance with the invention, therefore, a conical light beam is produced and, for this reason, the light-diverting means (protuberances of the reflector or flutes of the cover plate) are formed with a smooth surface structure, in order to be able to beam the light into given angular spreads or ranges.

In accordance with an additional optional feature of the invention and, depending upon the disposition of the lamp, the aperture angle of the light beam is between 20° and 90° and, advantageously, between 30° and 60°.

Especially if the light source is selectively in the focal region of the assistant reflector or in the focal region of the main reflector, in accordance with yet another feature of the invention, the main reflector has a greater parameter than that of the assistant reflector so that, when setting the light source in the main reflector, light that is as exactly parallel as possible is produced thereby. The greater the parameter of a reflector is in relationship to the size of the light source, the more accurately can the light rays within the light beam be directed in parallel.

In accordance with yet a further optional feature of the invention, the coaxial reflectors have a light outlet opening e main reflector of the two reflectors being located adjacent the light outlet opening.

With such an arrangement, a very large part of the light rays emitted by the light source can be captured. This is especially advantageous for lamps which should illuminate, actively, objects or surfaces and with which, therefore, the reflectors and the light source are adjustable or shiftable relative to one another. This construction is suited especially well for flash-lights and similar lamps used for illumination.

In order to be able to capture from the respective focal region as much light of the light source as possible, especially if it is selectively set in the one or the other focal region, and to bring the technical expense for the shifting of the light source down to an easily realizable value,' there is provided, in accordance with another feature of the invention, that the main reflector has a greater parameter than that of the assistant reflector, the smaller assistant-reflector parameter being from 55% to 80% of the greater main-reflector parameter.

In accordance with a further optional feature of the invention, the main reflector has a greater parameter than that of the assistant reflector, the transistion from the one reflector to the other reflector is of such construction that the spacing between both focal regions is 20% to 60%, advantageously 25% to 40%, and preferably 26% to 32% of the greater parameter.

In accordance with an added optional feature of the invention, and to achieve a good efficiency of the lamp, each of the focal regions is disposed in a surrounding space of the respective reflector associated therewith.

In accordance with an additional optional feature of the invention, and to achieve the best possible light distribution in the various light 463 5 2 beams, a plane disposed through the focal region of the main reflector and perpendicular to the lamp axis divides an angle stretching from the focal region of the main reflector to an outer and an inner edge of the main reflector so as to form an outer angle of at least 10°, advantageously at least 18° and preferably at least 25°, and an inner angle of at least 5°, advantageously at least 10° and preferably at least 15°. With this construction, the light beam produced by the main reflector has a very intense light. in accordance with yet another optional feature of the invention and with regard to the assistant reflector, a plane disposed through the focal region of the assistant reflector and perpendicularly to the lamp axis divides an angle stretching from the focal region of the assistant reflector to an outer and an inner edge of the assistant reflector so as to form an outer angle of at least 0°, advantageously at least 2° and preferably at least 5°, and an inner angle of at least 10°, advantageously at least 18° and preferably at least 25°. With the assistant reflector, it is also advantageous if the inner angle of light acceptance through the reflector is considerably greater than the outer one whereas, for the main reflector, this relationship should be reversed if possible.

In accordance with yet a further optional feature of the invention, an outer edge of the assistant reflector and an inner edge of the main reflector are closely adjacent one another.

In accordance with an alternative optional feature of the invention, an outer edge of the assistant reflector and an inner edge of the main reflector substantially coincide one with the other.

The same applies, obviously, when the reflectors are disposed in other successions or sequences, since the outer edge of the main reflector and the inner edge of the assitant reflector must then lie as near one another as possible or must at best coincide.

In accordance with yet another optional feature of the invention, the protuberances are in the form of calottes and have a height which is 3.5% to 12%, and preferably 4% to 8% of the smallest base diameter thereof , the greatest distance between two points of the light source being at least twice as great as the mean height of all the calottes.

In accordance with an alternative optional feature of the invention, the protuberances are in the form of rings and have a height which is 3.5% to 12%, and preferably 4% to 8%,- of the width of a respective ring, the greatest distance between two points of the light source being at least twice as great as the mean height of all the rings.

In accordance with yet an added optional feature of the invention, provided and advantageous for various applications, means are / for homogenizing light associated with the main reflector. Such light-homogenizing means should not divert the Tight to such an extent that it experiences a critical or decisive change in direction, but rather, the Tight rays should be only very slightly influenced in order to intermix the respective Tight beam better and also to distribute the light uniformly within this Tight beam. : If the Tight source is disposed in the focal point of the assistant reflector, one can determine that the light reflected from the main reflector emerges in a relatively narrow ring-shaped region through the cover plate. It is advantageous to furnish this ring-shaped region in the cover plate with the light-homogenizing means in the form, for example, of flutes, whereby the hollow-conical light beam of the light reflected by the main reflector is homogenized. If the light source, however, is disposed in the focal region FI of the main reflector, then a great part of the parallel light rays emerges outside of the ringshaped region of the cover plate which is provided with light-homogenizing means, i.e. a greater part of the light rays are not reached by these homogenizing means in this position, whereby the sharp parallelism of the light beam is maintained and only a given part is homogenized.

In accordance with yet an additional optional feature of invention, the flutes have a respective cross-section in the form of an obtuse triangle having legs forming flanks of the respective flute, the legs including, with the surface of the cover plate, a flank angle of 3° to 20°, and advantageously of 5° to 12°.

In accordance with another optional feature of the invention, for other applications, the light homogenizing means comprise protuberances (bulges and-or depressions) disposed on the reflecting surface of the main reflector and having an extremely slight curvature, i.e. a very large radius of curvature. Due to the extremely slight curvature, the light is not diverted from the main direction thereof, but rather, is homogenized somewhat only within the light beam. The main reflector could therefore also be provided with small facets; for example, the exactly parabolic shape of the reflectors could be broken down into a multiplicity of small reflecting surfaces or areas which are somewhat tangential to the mathematically ideal surface of the paraboloid. 46353 What is common to all these/light-homogenizing means is that they divert the light only quite negligibly. The: surface structure should likewise be quite smooth, i.e. highly polished, so that as little diffused light as possible occurs.

In accordance with a further optional feature of the invention, a collecting lens is disposed in axial direction of the lamp in front of the light source for capturing and collecting light rays emitted from the light source and emerging directly in direction of a light outlet opening of the lamp and superimposing the thus collected light rays on a light beam collected and united by the main and the assistant reflectors.

Such a collecting lens can be constructed, for example, as an integral part of the cover, plate.

In accordance with an added optional feature of the invention, the collecting lens is constructed as a collecting lens of a lens-end incandescent lamp, because thereby a considerably greater part of the light emerging from the light source can be captured and collected without the lens becoming so large that it disruptively affects the light beamed by the reflectors.

In accordance with an added feature of the invention, both the main and the assistant reflector are integral with one another.

In accordance with an additional optional feature of the invention, the lamp has a light intensity increasing with decreasing distance from the lamp axis so that part of the light beam which includes, with the lamp axis, an angle of 2°, has at least 2.1 times the light intensity of a part of the light beam which includes, with the lamp axis, an angle of 15°.

In accordance with an alternate optional feature of the invention, the lamp has a light intensity increasing with decreasing distance from the lamp axis so that part of the light beam which includes, with the lamp axis, an angle of 5°, has at least 1.8 times the light intensity of a part of the light beam which includes, with the lamp axis, an A angle of 15°-/1 ight distribution curve is thereby given which ensures that the light intensities, which have a given basic brightness as seen in the range of 15° from the axis, increase toward the axis so that travellers on the road which approach such a lamp on a straight road at high velocity are already warned while yet at a great distance therefrom.

If such a lamp is used as a flash-light, such as, for example, to illuminate the engine compartment of notor vehicle during repairs, then the greater brightness occurring in axial direction can be diverted, for example, directly upon the trouble spot such as, for example, a faulty spark plug, and nevertheless, adequate brightness is obtained in the surroundings of the axial region in order to perceive clearly all of the objects present in the engine compartment.

In accordance with a concomitant optional feature of the invention, the lamp has a light intensity increasing with decreasing distance from the lamp axis so that part of the light beam which includes, with the lamp axis, an angle of 2°, has at least four times the light intensity of a part of the light beam which includes, with the lamp axis, an angle of 15°.

In accordance with an alternative optional feature of the invention, the lamp has a light intensity increasing with decreasing distance from the lamp axis so that part of the light beam which includes, with the lamp axis, an angle of 5°, has at least twice the light intensity of a part of the light beam which includes, with the lamp axis, an angle of 15°.

Other features, essential and optional, of the invention are set 5 forth in the appended claims.

Although the invention is illustrated and described in several embodiments of lamp, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the invention and within the scope .. of the claims.

The construction and method of operation of the invention, however, together with additional objects and advantages thereof .will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which: Figure 1 is a plot diagram of a Tight distribution curve for an embodiment of a lamp or flash-light constructed in accordance with the invention, light intensities being plotted therein against the angles thereof to the axis of the lamp or flash-light; Figure 2 is a diagrammatic longitudinal sectional view of the lamp embodiment emitting the light of which the light distribution curve is plotted in Figure 1; Figure .3 is a fragmentary enlarged view of Figure 2 showing a socalled assistant or supplementary reflector below a parting or dividing line of the lamp; Figure 4 is a fragmentary top plan view of Figure 3 showing one of the curved surface portions of the assistant reflector; 6 3 5 2 Figure 5 is a cross-sectional view of Figure 4 taken along the smallest base diameter jl thereof; Figure 6 is an enlarged fragmentary view of Figure 2 showing the coiled luminous body thereof as constructed in accordance with the invention; Figure 7 is a view similar to that of Figure 6 of another embodiment of the luminous body; Figure 8 is a view similar to that of Figure 2 showing another embodiment of the lamp according to the invention; Figures 8a and 8b are enlarged fragmentary views of Figure 8 showing different embodiments of the lamp cover plate thereof formed with circular flutes having truncated triangular and round or parabolic cross-sections, respectively; Figure 9 is a view similar to those of Figures 2 and 8 showing yet another embodiment of the lamp according to the invention; Figure 10 is a fragmentary view of Figures 2 and 9 showing the reflector structure of the lamp in somewhat greater detail; Figure 11 is a view similar to that of Figure 10 of another embodiment of the lamp reflector structure; Figure 12 is a view similar to those of Figures 2, 9 and 10 showing the lamp reflector structure together with a cover plate constructed in accordance with the invention; Figure 12a i-s an enlarged fragmentary view of Figure 12 showing the flute formation in a part of the cover plate in clearer detail; Figure 13 is a view similar to that of Figure 10 showing yet another embodiment of the lamp reflector structure; Figure 14 is a view similar to those of Figures 2 and 9 showing a lamp with a reflector structure and cover plate similar to those of Figure 12; and 6 3 5 2 Figure 15 is a view similar to that of Figure 12 of yet a further different embodiment of the reflector structure.

Referring now to the drawings and first, particularly to Figure 1 thereof, there is shown a light distribution curve 74 of light intensities 72 shown in dependence upon the angle thereof to the axis 12 of the lamp according to the invention, an embodiment of which is illustrated in Figure 2. As shown in the plot diagram of Figure 1, the lamp is 70 represented to be at the point/and radiates light in direction of the axis 12 thereof corresponding to 0° on the abscissa of the illustrated coordinate system. ' This light distribution curve 74 was plotted for the light source 60 located in the focal region F2 of Figure 2. A bulging of the light intensities 72 is formed in the light distribution curve 74 at the regions 76, this.bulging being produced by the light beam 14 of the main reflector 10 and affording good illumination of the marginal zones of the combined conical light beam· 14, 16, If the lamp according to the invention is used as a signal Tamp, the bulge in the light intensities 72 at the regions 76 thus formed by the annular Tight beam 14 considerably improves lateral visibility of such a signal lamp.

Figure 2, as aforementioned, shows the lamp which emits the light in accordance with the light distribution curve 74 of Figure 1. The luminous body 60 of the incandescent lamp 61 is located in the focal region F2 of an assistant or supplementary reflector 30, Light rays emanating from the luminous body 60 and falling on the reflecting surface of the assistant reflector 30 are collected by the latter, with the aid of protuberances 42 formed in the reflecting surface thereof, into a conical beam having an aperture angle Ω1. . The light within this conical beam having the aperture angle'n 1 is advantageously distributed so that Λ6 3 S3 the light intensity of this beam 16 increases from the marginal regions to the axis 12 thereof. The main reflector 10 of the lamp or flashlight simultaneously emits an annular hollow conical beam 14 having an aperture angle aZ when the light source 60 is disposed in the focal region F2.

The conical beam 16 of the assistant reflector 30 should illuminate the dark middle zone of the annular hollow conical light beam 14 of the main reflector 10. Viewed outwardly from the axis 12, there is first the light beam 16 to which the annular conical light beam 14 can be seamlessly connected. The lamp according to the invention can also be constructed so that the marginal zones of the conical light beam 16 overlap the annular hollow conical light beam 14. Since the light beams 14 and 16, in any event, however, derive from various diameter regions of the hollow reflecting mirrors 10 and 30, a certain overlapping effect, depending upon the distance of the illuminated surface or object therefrom, will always occur anyway.

The lamp has a light aperture 22, the main reflector 10 has a focal region FI, and the assistant or supplementary reflector 30 borders on the main reflector 10 along a separating plane T. An incandescent lamp 61 is shown screwed into a lamp holder or socket 66 in Figure 2 and projects through a central opening 31 into the lamp. The lamp has a central axis 12, and is provided with a cover plate 50 in front of the light aperture 22.

Figure 3 shows part of a lamp constructed in accordance with the invention, namely the part with the assitant reflector 30 located below the separating plane T, as seen in the figure. To provide a better understanding of the construction of the lamp according to the invention, one of the protuberances 42 is shown in enlargement in Figure 3, and the smallest base diameter j5 and the height £ as well as the curvature radius £ thereof are also indicated. The light source 60 is disposed in the focal region F2 of the assistant or supplementary reflector 30. The centre of the focal region F2 of the assistant reflector 30 is spaced a distance S from the apex 33 of the parabolic assistant reflector 30. The incandescent lamp shown in Figure 3 has a flange base or cap 59.

Figure 4 illustrates one of the protuberances 42 in a greatly enlarged view, the smallest base diameter B thereof being readily apparent.

In Figure 5 there is shown a cross-sectional view of the protuberance 42 of Figure 4 taken along the smallest base diameter jl thereof. The original parabolic surface 48 of the assistant reflector 30 is indicated in Figure 5. The protuberance 42 rises to a height £ above the smallest base diameter 8 thereof. The radius of curvature £ of the protuberance 4? is also indicated in Figure 5.

The assistant reflectors 30 are advantageously constructed so that the parabolic reflecting surface thereof is provided with protuberances 42 (bulges and-or depressions), the mean height £ of all of the protuberances 42 being from 3% to 20%, advantageously from 3.5% tp 12% and preferably from 4% to 8% of the mean smallest base diameter B of all of ths protuberances 42, and the greatest spacing between two points of the light source being at least twice as large, advantageously at least three times as large and preferably at least five times as large as the mean height ji of all of the protuberances 42. Through the cooperation of a luminous body of defined dimensions with the protuberances 42, the dimensions of which have the foregoing relationship with the dimensions of the luminous body, a conical light beam is formed which, to an observer, increases in light intensity from the margin thereof toward the axis thereof.

The protuberance 42 shown in Figures 4 and 5 is not round. It 10 could, however, also be round, just as well. In the cases wherein protuberances 41 (Figure 15) are provided in the form of rings around the hollow mirror axis 12, the smallest diameter B_ of the respective protuberance 41 is equal to the width of the respective ring. If calculations are made with the mean values of the height ji and the smallest base diameter j3 of all the protuberances 42, this then confines the possibility of individual sharp deviations from these means values. The smaller the deviations from the mean values, the better is the light distribution that is attained.

The best results are obtained if the height ji substantially of each individual protuberance is from 3% to 20%, advantageously 3.5% to 12% and preferably 4% to 8% of the smallest base diameter B thereof. It is furthermore advantageous if the greatest extension of the projection of the luminous body °n a plane perpendicular to the direction of the greatest extension thereof is at least 25% of the mean height _h of all of the protuberances 42, and advantageously the smallest base diameter 8 of each individual protuberance is 5% to 40%, advantageously 7% to 30% and preferably 9% to 25% of the spacing of the apex of the parabolic hollow mirror reflector from the focal point thereof or from the middle of the focal region thereof. ,46352 Good results are attained if the surfaces of the protuberances 42 are formed as spherical calottes advantageously having a radius of curvature r between 10% and 70%, preferably between 15% and 50%, of the spacing of the middle of the focal region from the apex of the assistant reflector . Ih Figures 2, 3, 9, 10, 11, 12, 13, 14 and 15, the assistant concave reflector 30 is generally parabolic if the small deviations due to the protuberances are ignored.

To control the light distribution, it can be advantageous if.the surfaces of the protuberances are cut-away portions or sections of ellipsoids or ellipsoidal surfaces, and the plan view of the base of the protuberances is elongated, advantageously elliptical or nearly or somewhat elliptical.

In an advantageous embodiment, as aforementioned, the protuberances can be constructed in the form of rings coaxially or concentrically surrounding the axis of the hollow mirror reflector, the surfaces of the rings being advantageously cut-away portions or sections of toroidal surfaces. Also 7 as noted hereinafter, the smallest base diameter of a respective ring-shaped protuberance 41 corresponds to the width of one of the rings. Such ringshaped protuberances are shown in Figure 15.

The surface structure of the protuberances 42 should be as smooth as possible, because no diffused light but rather a conical light beam with quite specific, aperture angles is supposed to be produced.

Figure 6 shows a coiled luminous body of an incandescent lamp. The greatest distance between two points of this luminous body is indicated by the measurement This greatest spacing .b between two points of the light source should be at least twice as large as the mean height h^ of the protuberances 41 or 42. 6 3 5 2 Figure 7 shows a differently shaped luminous body from that in Figure 6. Also in Figure 7, the greatest distance between two points of the luminous body 2 is indicated by the measurement b. In Figure 7, as well, the greatest spacing between two points of the luminous body should be at least twice as large as the mean height h. of all of the protuberances 41 or 42.

Figure 8 shows a lamp similar to that in Figure 2 with the difference, however, that both the main concave reflector 10 and the assistant concave reflector 30 have a reflecting surface that is formed without any bulges and/or depressions. For that reason, light-bending or diverting means are provided in a ring-shaped region 54 of the cover plate 50 which is impinged upon by parallel-directed light rays from the assistant reflector 30, so as to divert the axial parallelism of these light rays into a conical light beam with an aperture angle of, for example 40/, in order to supplement, radially inwardly, the ring-shaped conical light beam 14 produced by the main reflector 10 or, if desired, also to overlap the light beam 14. In the case at hand, the light-diverting or bending means, which are located in the region 54, are made up of flutes incised or formed in the cover plate 50 and encircling the axis 12, the flutes having flanks 32 that are so inclined as to break the light into the desired aperture angle.

If it is desired to receive specially great light intensities in axial direction, the bottoms or the points of these flutes can be made piano parallel so that light does not experience any change in direction thereat.

This is shown in Figure 8a. Figure 8b shows a different type of the flutes 35 having a round or, preferably, also a parabolic cross-section in order thus to form the light distribution homogeneously within the light beam 16. naturally, other light-diverting means, such as circular ring-shaped lenses, for example, can also be used for diverting or bending the light into the desired aperture angle in the region 54.

Figure 9 shows the same lamp as in Figure 2 with the difference, however, that the main reflector 10 and the auxiliary or assistant reflector 30 have been so shifted with respect to the light source 60 in direction of the lamp axis 12 that the light source 60 is no longer located in the focal region FI of the main reflector 10. In this location of the light source, a narrow, substantially parallel light beam 13 is produced by the smooth reflecting surface of the main reflector 10. The reflecting surface of the main reflector 10 could also be equipped with very slight bulges and/or depressions for homogenizing the substantially parallel bright light beam. The main reflector 10 terminates at the plate T at which it borders on or abuts the assistant reflector 30 having the focal region F2. Advantageously, both hollow mirror reflectors 10 and 30 are formed of one piece. Both hollow mirror reflectors 10 and 30 have the same lamp axis 12. In the vicinity of the apex of the assistant reflector 30 is an opening 3T through which the light source, such as the luminous body of an incandescent lamp, for example, projects into the reflectors 30 and 10.

The holder or mounting support for the hollow mirror reflectors 30 and 10, on the one hand, and the light source 60, on the other hand, should be so constructed that the light source 60 and the reflectors 30 and 10 can be shifted or adjusted relative to one another in axial direction so that the light source 60 can be brought selectively into the focal 6 3 5 2 region Fl or into the focal region F2. In Figure 9, the light source 60 of the incandescent lamp 61 is located in the focal region Fl of the main reflector 10 which emits the parallel light beam 13 in this setting. In practice, not all of the light rays are exactly parallel because the luminous body 60 of the incandescent lamp 61 is not ideally punctiform and also the reflector 10 can obviously be produced only nearly but not mathematically exactly. Due to these slight deviations, the light beam 13 is, indeed, substantially parallel at a given short distance from and in front of the lamp yet, however, is already so well intermixed that it appears to the viewer as a closed parallel light beam.

Figure 10 shows an embodiment of a lamp according to the invention which is similar to that of Figures 2 and 9, but which has been provided additionally for explaining the angle of light acceptance. A plane SF1 perpendicular to the axis 12 is disposed through the focal region Fl of the main reflector 10. This plane FS1 and a straight line 28 intersecting therewith and passing through the focal region Fl and through the outer edge 23 of the main reflector 10 include an angle al of about 31°. Furthermore, this plane SF1, with a straight line 29, which extends through the focal region Fl and the inner edge 26 of the main reflector 10, includes an angle el of about 21°. Altogether, light beams emitted from the focal region Fl are held by the main reflector 10 within the range of an angle al + el = 52°.

A plane SF2 perpendicular to the axis 12 is disposed through the focal region F2. This plane SF2, with a straight line 20 which extends through the focal region F2 and the outer edge 26 of the assistant reflector 30 includes an angle a2 of about 5°. The lightacceptance angle of the assistant reflector 30 is limited by a straight line 21 below the plane SF2, as viewed in Figure 10, the straight line 21 extending through the inner edge 18 of the assistant reflector 30 at the inlet opening 31 for the incandescent lamp. The angle g2 between the plane SF2 and the straight line 21 is about 33° in the case at hand.

Altogether,if the light source is located in the focal region F2, light is thus held by the assistant reflector 30 in an angle range of a2 + ¢2 = 38°. The spacing of both focal regions Fl and F2 from one another is about 30% of the parameter of the main reflector 10.

The parameter of a parabola is twice as Targe as the spacing of the focal point of the parabola from the apex of the parabola. The focal region Fl is surrounded by the main reflector 10, and the focal.region F2 by the assistant reflector 30. The parameter of the assistant reflector 30 is, in this case, 68% of the parameter of the main reflector 10.

Figure 11 shows a hollow mirror reflector having a main reflector 10 with a greater parameter than that of the assistant reflector 30 thereof.

The focal region of the main reflector 10 is located at Fl, whereas the focal region of the assistant reflector 30 is at F2. If the light source is disposed in the focalregion Fl, the main reflector 10 then emits nearly parallel light. If the light.source is then brought into the focal region F2 of the assistant reflector 30, the hollow mirror reflector 10 then produces a ring-shaped conical light beam which is illuminated in the inner region thereof by a conical light beam of the assistant reflector 30. This conical light beam brightens or illuminates the aperture angle thereof due to the protuberances 42 provided on the surface of the assistant reflector 30. , In the embodiment of the invention shown in Figure IT, the main reflector Ϊ0 could naturally, also be extended to the light outlet opening 22, as presently illustrated inthe figure, and the assistant 463S3 reflector 30 with the protuberances 42 thereof could then be disposed beyond or forward of the presently shown light outlet opening 22 located at the end of the thus elongated main reflector 10.

Figure 12 shows an embodiment of a lamp similar to that shown in Figures 2, 9 and 10. If the light source is brought toward the focal region F2, a surprising observation is made that most of the light rays that are collected by the main reflector 10 emerge through a relatively narrow ring-shaped region 52 of the cover plate 50. In order to homogenize somewhat this narrow ring-shaped region of the hollow conical light beam 14, ring-shaped flutes encircling the axis 12 are provided in the cover plate 50 at the region 52. In Figure 12a, such flutes 53 are shown in an enlarged view for a better understanding of the construction thereof. It has been found to be sufficient if these flutes 53 form with the flanks 55 and 56 thereof an angle of only 3° to 20°, and preferably 5° to 12°, with the plane of the cover plate 50. Advantageously, these or other light distributing means are provided in this region 52 at the inner side of the cover plate 50 so that they do not become filled with dust. If the light source is then brought toward the focal point Fl of the main reflector 10, the parallelism of the light beam then becomes impaired somewhat (homogenized) only in the small ring-shaped region of the flutes at 52, whereas the light rays in the entire remaining region of the cover plate 50 can emerge undisturbed in parallel. Through the small region 52 provided with only limited light-distributing means, only a given homogenization of a small part of the parallel rays occurs in the bright light beam, which has barely any negative effect upon the range of the parallel light beam yet gives the light beam a greater uniformity.

Figure 13 shows a lamp similar to the lamps shown in Figures 2, 9 and 10, yet with the difference that, in Figure 13, the main reflector 10 is provided with quite weakly punched out or embossed bulges and-or depressions, such as protuberances 43, for example. These do not have the function of distributing the light over a large angle range, but rather, because of the very weak optical efficiency-thereof, serve only for homogenizing the parallel light beam when the light source is set in the focal region Fl. Obviously, if the light source is brought toward the focal region F2, the ring-shaped hollow conical light beam 14, which then emerges from the main reflector 10, is thereby also homogenized.

Figure 14 illustrates an embodiment of a lamp according to the invention which is similar to the embodiment in Figure 12. A collectingor condenser lens 62 is disposed, in this case, in front of the light source 60. If the light source 60 of the lens-end incandescent lamp 64 is set in the focal region F2 of the assistant reflector 30, the main reflector 10 then delivers a light ring which is filled out by the conical light beam thatis collected by the assistant reflector 30 and fanned out due to the light-distributing protuberances 42. The light rays, which would otherwise emerge ineffectually, without beaming, through the light outlet opening 22 of the main reflector 10, are thus formed into a beam by the collecting lens 62 and overlaps both light beams thrown by the hollow mirror reflectors 10 and 30. An especially good homogenization and reinforcement of the illumination in these combined light beams is thereby attained. The socket or 6 3 5 2 receptacle 66 into which the lens-end incandescent lamp 64 is screwed, tapers or narrows down in a part 68 thereof so that the assistant reflector 30 can slide with the opening 31 thereof over this socket part 68, when the light source 60 is shifted into the focal region Fl, if the main reflector 10 is supposed to produce a parallel light beam.

Figure 15 shows a lamp similar to that in Figure 12 but wherein the assistant reflector is furnished, however, with protuberant rings 41 running around the axis 12 instead of with dome and-or cup-shaped protuberances 42.

Claims (29)

C L A I MS

1. Lamp having a main and an assistant reflector disposed mutually coaxially and having different parameters and different focal regions, said different focal regions being located within said common axis and having a distance from each other, said lamp comprising a light source disposed at least adjacent the focus of the assistant reflector so that the main reflector emits a hollow light beam, and means associated with the assistant reflector for diverting light of the assistant reflector into a solidly conical light beam whose aperture angle corresponds to that of the hollow light beam of the main reflector to such an extent that both said hollow and solidly conical light beams exhibit at least one of the characteristics of supplementing and overlapping one another.

2. Lamp according to claim 1, wherein said light diverting means comprise protuberances in the form of a plurality of at least one type of structural features selected from the group thereof consisting of bulges and depressions formed in the reflecting surface of the assistant reflector, all of said protuberances having a mean height that is 3. % to 20% of a mean smallest base diameter of all of said protuberances, a maximal spacing between two points of said light source being at least twice as large as the mean height of all of said protuberances.

3. Lamp according to claim 1, wherein said light diverting means comprise flutes formed in a cover plate located at a light outlet end of the reflectors, said flutes being in a region of said cover plate through which the light of the assistant reflector passes.

4. Lamp according to claim 1, wherein said light source, on the one hand, and the reflectors, on the other hand, are adjustably shiftable in axial direction relative to one another so that said light source is 463 52 selectively disposable in either of the focal regions, (or in between said focal regions) said light source, when in the focal region of the main reflector said main reflector emitting a substantially parallel main light beam.

5. Lamp according to claim 1, wherein said light-diverting means associated with the assistant reflector and diverting the light into a conical light beam have a smooth surface structure.

6. Lamp according to claim 1, wherein said aperture angles of said light beams are between 20° and 90°, and advantageously between 30° and 60°.

7. Lamp according to claim 1, wherein the main reflector has a greater focal length than that of the assistant reflector.

8. Lamp according to claim 1, wherein the coaxial reflectors have a light outlet opening, the main reflector of the two reflectors being adjacent said light outlet opening.

9. Lamp according to claim 1, wherein the main reflector has a greater focal length than that of the assistant reflector, the smaller assistant-reflector focal length being from 55% to 80% of the greater main-reflector focal length.

10. Lamp according to claim 1, wherein the main reflector has a greater parameter than that of the assistant reflector, and the spacing between both focal regions is 20% to 60%, advantageously 25% to 40%, and preferably 26% to 32% of the greater parameter.

11. Lamp according to claim 1, wherein each of the focal regions is disposed in a surrounding space of the respective reflector associated therewith.

12. Lamp according to claim 1, wherein a plane disposed through the focal region of the main reflector and perpendicularly to the lamp axis divides an angle stretching from the focal region of the main reflector to an outer and an inner edge of the main reflector so as to form an outer angle of at least 10°, advantageously at least 18° and preferably at least 25°, and an inner angle of at least 5°, advantageously at least 10° and preferably at least T5°.

13. Lamp according to claim 1, wherein a plane disposed through the focal region of the assistant reflector and perpendicularly to the lamp axis divides an angle stretching from the focal region of the assistant reflector to an outer and an inner edge of the assistant reflector so as to form an outer angle of at least 0° advantageously at least 2° and preferably at least 5°, and an inner angle of at least 10°, advantageously at least 18° and preferably at least 25°.

14. Lamp according to claim T,. wherein an outer edge of the assistant reflector and an inner edge of the main reflector are closely adjacent one another.

15. Lamp according to claim 1, wherein an outer edge of the assistant reflector and an inner edge of the main reflector substantially coincide one with the other.

16. Lamp according to claim 2, wherein said protuberances are in the form of calottes and have a height which is 3.5% to 12%, and preferably 4% to 8%, of the smallest base diameter thereof.

17. Lamp according to claim 2, wherein said protuberances are in the form of rings and have a height which is 3.5% to 12%, and preferably 4% to 8%, of the width of a respective ring.

18. Lamp according to claim 1 including means for diffusing light associated with the main reflector.

19. Lamp according to claim 18, wherein said light source is disposed in the focal point of the assistant reflector, and said light-diffusing means comprises flutes formed in a ring-shaped region of a cover plate located at a light outlet end of the reflectors, said ring-shaped region forming an outlet for light reflected from the main reflector in the shape of a conical ring-shaped light beam.

20. Lamp according to claim 19, wherein said flutes have a respective cross section in the form of an obtuse triangle having legs forming flanks of the respective flute, said legs including, with the surface of said cover plate, a flank angle of 3° to 20°, and advantageously of 5° to 12°.

21. Lamp according to claim 18, wherein said light homogenizing means comprise protuberances disposed on the reflecting surface of the main reflector and having a very large radius of curvature.

22. Lamp according to claim 1 including a collecting lens disposed in axial direction of the lamp in front of said light source for capturing and collecting light rays emitted from said light source and emerging directly in direction of a light outlet opening of the lamp and superimposing the thus collected light rays on a light beam collected and united by the main and the assistant reflectors.

23. Lamp according to claim 22, wherein said collecting lens is constructed as a collecting lens of a lens-end incandescent lamp.

24. Lamp according to claim 1, wherein both the main and the assistant reflector are integral with one another.

25. Lamp according to claim T having a light intensity increasing with decreasing distance from the lamp axis so that part of the light beam which includes, with the Tamp axis, an angle of 2°, has at least 2.1 times the light intensity of a part of the light beams which includes, 5 with the lamp axis, an angle of 15°.

26. ; Lamp according to claim 1 having a light intensity increasing with decreasing distance from the Tamp axis so that part of the light beam which includes, with the lamp axis, an angle of 5°, has at least 1.8 times the Tight intensity of a part of the light beam which includes, 10 with the lamp axis, an angle of 15°.

27. Lamp according to claim 1 having a Tight intensity increasing with decreasing distance from the lamp axis so that part of the light beam which includes, with the lamp axis, an angle of 2°, has at least four times the light intensity of a part of the light beams which includes, 15 with the lamp axis, an angle of 15°.

28. Lamp according to claim 1 having a light intensity increasing with decreasing distance from the lamp axis so that part of the light beam which includes, with the lamp axis, an angle of 5°, has at least twice the light intensity of a part of the light beam which 20 includes, with the lamp axis, an angle of 15°.

29. A lamp constructed and arranged substantially as hereinbefore described with reference to any one of the embodiments illustrated in the accompanying drawings. Dated this 11th day of September 1978, (signed) 'T0MKINS & CO., ApfWicants' Agents, 5 Dartmouth Road, DUBLIN 6 4 63 52L sheet 1 Knut Otto Sassmannshausen