EP0854317A2 - Reflector and lamp comprising the same - Google Patents

Abstract

The reflector for an annular light source or an elongated one with two limbs has the contour formed at least partly out of evolute sections, whereby two sections touch each other in a crest point. The contour has in total four evolute sections of which each two evolutes of opposing direction are assigned to one limb of the light source. The arrangement is rotationally symmetrical or axisymmetrical relative to an axis that is stretched out between the two limbs. The crest point lies "in approximately on" the straight lines connecting the middle of the limbs so that a longer and a shorter evolute section is assigned respectively to one limb.

Description

Technical field

The invention is based on a reflector according to the preamble of the claim 1. It is particularly a reflector for extended Light sources, especially around elongated light sources such as multi-legged ones or ring-shaped fluorescent lamps or similar shaped electrodeless, Microwave excited lamps (see DE-OS 2 601 666). Under The term light source is also intended to be a radiation source, the IR or UV radiation emitted can be understood.

State of the art

DE-OS 27 55 253 is already a channel reflector for an elongated one rod-shaped light source, in particular a fluorescent lamp, is known, whose intersection curve consists partly of two adjoining involutes (see below) is formed. The two involute branches either touch each other not at all and end on the light source, in relation to the light exit opening behind the light source, or they touch behind the Light source (related to the light exit opening) at a certain distance from the light source. This intersection of the two involutes should be in the hereinafter referred to as the vertex.

EP-A 442 246 describes a very similar reflector for a rod-shaped one Light source known, the intersection of two mirror-symmetrical involute branches form, whose apex is also behind the light source and exactly in the normal to the light exit opening. The involutes leave towards the light exit opening in parabolic branches.

Such a technique as is suitable for single-leg light sources does not work well for elongated light sources with two legs use because such a reflector no longer all light on the Could reflect light source past.

Presentation of the invention

It is an object of the present invention to provide a reflector according to the Provide the preamble of claim 1, which also in the case of an elongated Light source with two legs all light at the light source reflected over. Another task is to find an appropriate luminaire specify with such a reflector.

This object is achieved by the characterizing features of claim 1 solved. Particularly advantageous configurations can be found in the dependent ones Claims.

When radiation emitted by an extended light source is on the source is reflected back generally passes through part of it Absorption lost. The following is a reflector for a radiation source with two legs with circular or elliptical or similar Cross section (e.g. a fluorescent lamp in compact form or U-shaped bent) described, which reflects all light past the light source and thus avoids losses due to self-absorption. In the simplest Fall be except for the requirement that no radiation is on the light source is reflected back, no further conditions are taken into account. In in this case the reflector has the property of being the smallest possible Has dimensions. In particular, the angular distribution of the radiation intensity remains (Indicatrix) open. This can be achieved through specific deviations from the described Reflector profile can be influenced. The calculation principle developed here provides a limit curve that in practice applies to the respective Application can be adapted, with compromises then Efficiency and / or reflector size can be entered. The cutting contour of the reflector can be found near the light exit opening described, for example, by parabolas or oblique plane surfaces be.

For a better understanding of the invention, a more detailed explanation is first the properties of involute reflectors necessary.

The basic idea has long been known per se and is demonstrated using FIG. 1. A radiation source 1 has a circular cross-section with the radius R. The radiation it emits is completely reflected past the source when the cutting line of the reflector is an involute (a simple derivation of this spiral curve is given, for example, in K. SÖRENSEN: Design of Optical Systems for Luminaires, The Lighting Journal, pp. 5-7, March 1990). An involute fulfills the condition that the following applies to every part of the reflector: The boundary beam emitted tangentially from a point K on the surface of the light source 1 in the direction of any reflector point L must be reflected past the source on the right. As a result, all other rays emitted from the source in the direction of point L up to a limit point M arranged on the opposite side of the light source, including the limit beam emanating from M (dashed line), are reflected even more past the light source. In the borderline case, which delivers the smallest possible reflector shape, the beam KL is reflected in itself. 1, this results in the mathematical definition of this limit curve in differential form: dϕ = (1/ R ) 2nd -(1/ r ) 2nd dr ϕ and r are the polar coordinates of the reflector curve. The smallest possible reflector curve itself is obtained by graphically or mathematically integrating (1). The solution can be given in closed form: Φ (r) = Φ 0 ± { ( r / R ) 2nd -1 + arccos (R / r)}

The starting point of the involute on the surface of the light source is indicated by Φ ₀ . For the above considerations it is assumed that the lamp axis lies in the coordinate origin (at r = 0). The size Φ ₀ is referred to below as the angle of rotation.

The result is a spiral, which in the simplest case is radial from the surface of the light source (Point B) goes out, see Fig. 1, and in professional circles as Is called involute. The involute is clearly the scope of the Lamp cross-section, and thus i.a. its radius R assigned.

The general rule is that reflectors with larger than minimal dimensions can also be used: dϕ ≤ (1/ R ) 2nd -(1/ r ) 2nd dr

In principle, any section of the above involute can be used as a reflector to be chosen. In particular, a section can be used that does not attach to the surface of the light source. It can also be additional the mirror image can be used, i.e. an involute that opposes each other opens.

For the known case of the single-leg light source, FIG. 1 shows as an example a reflector 2 for a light source 1 with a circular cross-section, whose intersection curve 3 meets the above conditions. From two opposing involute branches 3a and 3b become the curve parts AB and BF used. The light exit opening 4 (level through the Points A and F) is at the height of the lower edge of the lamp. This arrangement only radiates into the lower half space. The two involute branches were put together so that they were in the apex, namely the common point B, start from the lamp surface. This arrangement theoretically provides the smallest dimensions for the Width b and the height h of such a reflector, namely b = 6.3 R and h = 2.5 R.

In practice, two opposing involute branches are used, their Apex is arranged above the surface of the light source.

According to the invention, the above principle can be modified by a suitable modification can also be applied to lamps with two legs.

To achieve that, despite the second leg, no light on the light source is thrown back, the cut surface of the reflector consists of a total of four involute branches. Two each are one leg of the light source assigned. The arrangement with respect to the other leg is mirrored axially symmetrical, with the axis in the middle between the Thighs runs.

The apex of the two involute branches assigned to one leg is not arranged behind the light source as before (i.e. from the plane of the Light exit opening seen approximately in their normal), but on the other hand, rotated by 90 ° and towards the second leg. Here too a certain margin is allowed, the size of which is approximately as defined above Corresponds to the angle diameter. The vertex is between the two Don’t. The length of the two involute branches is determined by this arrangement very different. The angular length of the longer branch is more than 180 °, that of the shorter branch significantly less than 90 °. Especially the shorter branch ensures that no radiation from the first leg falls on the second.

According to the invention, it is therefore a reflector for an annular one Light source or an elongated light source with two legs, wherein the contour of the reflector at least partially from sections of involutes is formed. Two sections touch at a vertex. The contour has a total of four involute sections, one of which two oppositely oriented involutes each one leg of the Light source are assigned. The arrangement is rotationally symmetrical (in Case of ring-shaped lamps) or axially symmetrical (in the case of an elongated one Light source) with respect to an axis that lies in the middle between the is stretched two legs, the apex approximately on the the middle of the legs connecting straight lines lies, so that a longer one and a shorter involute section (branch) is assigned to one leg is.

The vertex S can be offset somewhat from the straight line be. It can typically be offset by the angle ε = 10 ° to 20 ° if ε is the Angle between the straight line SO (vertex origin) and the connecting straight line between the legs.

Both the two longer and the two shorter involute branches usually touch between the two legs. The two Points of contact span an (imaginary) straight line that defines the axis of symmetry of the reflector.

The contour of the reflector can have other sections that form the indicatrix the radiation emitted to the target to adjust. In particular, another section can be longer Apply involute branch and in particular have parabolic shape or as be inclined plane surface.

In the reflector between the two legs, a support or Partition made. The partition can in particular between the two points of contact (B and D in Fig. 2) of the involutes extend.

There are several options for the design of the partition. In In one embodiment, the partition has at least the two shorter ones Involute branches as a contour. In particular, the partition can also include a contour near the vertex of the longer involute. Some of the shorter involute branches can also be missing, in particular these branches can also be missing entirely.

The partition often has a simplified one compared to the involute Contour, for example an oblique or straight wall.

The reflector according to the invention can be used as a channel reflector for a lamp be used, the light source is a lamp, the bulb two parallel Owns thigh. In particular, it can be an electrodeless one Act lamp with a closed bulb, the bulb in plan view, be a tube with an oval or approximately rectangular shape can. Alternatively, a conventional fluorescent lamp with a curved U-shaped tube or other light source can be used.

In practice, however, it must be considered whether the complicated design of the Partition between the legs in favor of poorer lighting efficiency is simplified. For example, part of the shorter one Branch omitted. Or in the separation area, the reflector contour is simplified selected or simply designed as a straight separator.

In particular, an annular or two-legged light source is used Electrodeless lamp in question, in which the two legs of the lamp vessel are connected at both ends and so a closed Form tube. The self-contained tube preferably forms one Oval or rounded rectangle. Such a lamp is for example in PCT / EP96 / 03180 (Art. 54 (3)). In principle, however, is any other Radiation source with two legs is also suitable.

Of course, several such reflector systems can be placed side by side can be arranged, in principle also lamps with four or more legs can be used side by side.

characters

Figur 1

das Grundprinzip der Evolvente

Figur 2

ein Ausführungsbeispiel eines Reflektors für eine zweischenkelige Lampe im Schnitt

Figur 3

ein weiteres Ausführungsbeispiel eines derartigen Reflektors

Figur 4

ein drittes Ausführungsbeispiel eines derartigen Reflektors

Figur 5

ein viertes Ausführungsbeispiel eines derartigen Reflektors

Figur 6

ein Ausführungsbeispiel einer Leuchte mit Reflektor

Figur 7

ein weiteres Ausführungsbeispiel einer Leuchte mit Reflektor

Figur 8

ein fünftes Ausführungsbeispiel eines derartigen Reflektors

The invention will be explained in more detail below with the aid of several exemplary embodiments. They show schematically:

Figure 1

the basic principle of the involute

Figure 2

an embodiment of a reflector for a two-legged lamp in section

Figure 3

another embodiment of such a reflector

Figure 4

a third embodiment of such a reflector

Figure 5

a fourth embodiment of such a reflector

Figure 6

an embodiment of a lamp with reflector

Figure 7

another embodiment of a lamp with reflector

Figure 8

a fifth embodiment of such a reflector

Description of the drawings

Figure 1 has already been explained in detail above.

Figure 2 shows a reflector 5 according to the invention for a lamp whose Piston has a first and second elongated legs 6a and 6b. The reflector contour consists of a total of four involute branches 7a-d, von which the two oppositely oriented involute sections 7a and 7b are assigned to the first leg 6a of the light source, while the two oppositely oriented involute sections 7c and 7d the second Leg 6b of the light source are assigned.

The arrangement of the involute branches is axially symmetrical with respect to a plane Z that spans in the middle between the two legs 6a and 6b is. The two oppositely oriented involute sections 7a and 7b associated with the first leg 6a of the light source a common vertex C, this vertex on the The middle of the two legs 6a and 6b connecting straight line X lies so that each a longer (7a) and a shorter (7b) involute section (branch) is assigned to the first leg 6a. In the same way, but mirror-symmetrical, are the two oppositely oriented involute sections 7c and 7d assigned to the second leg 6b of the light source, the longer one Branch 7c and the shorter branch 7d have a common vertex E on the straight line X.

In this arrangement, the distance a between the two legs 6a and 6b is a = 2.1 R, the width of the entire reflector is b = 14.4 R and the height h = 4.6 R.

The reflector contour here consists of the curve sections AB, BC, CD, DE, EB and BF. They are designed so that no radiation on the source is reflected back.

The sections CD, DE, BC and EB also ensure that no radiation from one leg falls on the other. Of course in To check on a case-by-case basis what gain in light is complicated at this point Reflector shape supplies.

The two lower reflector parts CD and DE and possibly also the upper BC and EB can at least partially disappear when radiation is abandoned.

FIG. 3 shows a reflector which essentially corresponds to that in FIG. 2. The involute branches 10a and 10b associated with the first leg 11a are, however, have a different origin on the piston surface, accordingly another, smaller difference in the angle of rotation. Remarkable is that the dimensions a, b and h (= leg distance, width and Height of the reflector) become smaller. The following applies: a = 1.35 R; b = 12.9 R and h = 4.2 R. So a decreases most strongly. That is, the closer points C and E are to move the piston surface, the smaller the distance a between the thighs without radiation being reflected on the lamp.

The dimensions a, b and h given in FIGS. 2 and 3 are calculated values without considering the physical reflector wall thickness d. In the Practice must be added to d or 2d. The thickness of a partition (see below) is not considered.

FIG. 4 shows a reflector which is modified in such a way that the longer involute branch 14a, starting from the vertex C, does not reach the light exit opening (point A), but only up to point T ₁ . From T ₁ to A, a section of the reflector contour is designed as a parabola 14c (or also as an oblique plane surface 14d, shown in broken lines in FIG. 4). Between the two legs 15a and 15b there is a separating web 16, the contour of which follows the sections BC and BE of the longer involute branches and part of the shorter involute branches 14b, namely CD and ED. The remaining part of the shorter involute branch 14b is omitted.

5 shows a further exemplary embodiment of a rotationally symmetrical or axially symmetrical reflector, in which the apices S ₁ and S ₂ lie on a straight line inclined upward by approximately 10 ° with respect to the connecting line X, specifically between the two intersecting circles of the ring or the two legs 22a and 22b of a piston shaped as a U. The dividing wall 20 has a contour which comprises the section BS _{1 of} the longer involute branch 21a and a replacement contour for the shorter involute branch, namely a slope 21b. In cross-section, the right half of the cut surface of the reflector is designed to be rotationally symmetrical or, again, a mirror image of the left half.

In Fig. 6a is a lamp 30 is a highly schematic plan view of the light exit opening shown in the case of an annular compact electrodeless Fluorescent lamp 31 with a bulb 22. FIG. 6b shows one similar lamp 40 with a channel reflector and a U-shaped Fluorescent lamp 44, in which the connecting bow 41 (shown in dashed lines) and the base 42 are each covered by panels 43.

FIG. 7 shows a lamp 50 in plan view from the light exit opening, that of a channel reflector 51, as shown below in FIG. 8 (or also for example in Figure 4 or 5), in connection with a electrodeless fluorescent lamp 52 exists. The lamp consists of a Housing with two long sides 53 and two short sides 55. The fluorescent lamp 52 is centered in the housing. It consists of one tubular discharge vessel that forms a closed loop that there are two long legs 54, 56 and two short connecting parts 58, 60. The connecting parts 58, 60 are each of ferrite transformer cores 62, 64 surrounded with windings, with the help of which the lamp is also fixed in the reflector is. The long legs 54, 56 are axially parallel to the axis of the channel reflector 51 arranged.

The short sides 55 of the reflector are mirrored. The reflector contour consists of a longer involute branch which extends from the apex line S ₁ to the opening on the line containing the point A. The shorter involute branch lies between the two legs 54, 56 and extends from the apex S ₁ to the line containing the end point D at the light exit opening. Instead of the shorter involute branch, a simplified curve shape (for example a slope as in FIG. 5) can also be used.

In Figure 8 is the section of the reflector 51 for the electrodeless fluorescent lamp 52 shown with two legs 54 and 56. The legs 54 and 56 are by connecting parts 58, 60 (the latter is not visible) with at least connected to a ferrite core 62. The core 62 is through a support member 65 attached to the housing.

In a specific implementation, an electrodeless fluorescent lamp with an output of 150 W is used as the lamp, the legs of which have a tube diameter of approximately 52 mm and are therefore much thicker than conventional fluorescent lamps. In a channel reflector made entirely of the four involute branches, this lamp achieved a luminaire efficiency of almost 90% compared to approximately 70% for a conventional channel reflector. The reflector housing has a width of approximately 350 mm and a height of 110 mm. The distance T between the lamp legs is about 33 mm. The reflector 51 is a minimal reflector whose vertices (or actually lines) S ₁ and S ₂ lie on the connecting line X and lie directly on the legs. The reflector contour consists of two short and long involute branches 59a, 59b and 61a, 61b. The attached Cartesian coordinate system gives an impression of the size of the lamp (details in mm).

To improve the light distribution towards the outside, bevel is used Flat surfaces (or parabolas), you get a lamp with an almost cosine shape Light distribution.

Claims (14)

Reflector for an annular light source or an elongated light source with two legs, the contour of the reflector being formed at least partially from sections of involutes, with two sections touching at an apex, characterized in that the contour comprises a total of four involute sections (21a-d) of which two oppositely oriented involutes (21a, b) are each assigned to one leg (22a) of the light source, the arrangement being rotationally symmetrical or axially symmetrical with respect to an axis of symmetry (Z) which is located in the middle between the two legs ( 22a, b), the apex (S ₁ ) lies approximately on the straight line (X) connecting the middle of the legs, so that a longer (21a) and a shorter (21b) involute section (branch) each leg ( 22a) is assigned. Reflector according to claim 1, characterized in that the apex (S ₁ ) lies on the straight line (X), as seen from the origin O, by up to approximately ± 20 ° inclined relative to the connecting line (X). Reflector according to claim 1, characterized in that the contour of the reflector has further sections (14c) which ensure uniformity improve the radiation. Reflector according to claim 3, characterized in that the further Section begins at the longer involute branch and in particular parabolic shape owns. Reflector according to claim 1, characterized in that between the two legs a partition (20), which partially the axis of symmetry includes, is introduced. Reflector according to claim 5, characterized in that the partition has at least the two shorter involute branches as a contour. Reflector according to claim 5, characterized in that the partition partially or completely in the area of the shorter involute branches is missing. Reflector according to claim 5, characterized in that the partition has a simplified contour (21b) compared to the involute. Reflector according to claim 5, characterized in that the partition also a part of the longer involute near the vertex as a contour included. Luminaire (50) with a reflector according to claim 1 and a light source, characterized in that the light source is a lamp (52), the Piston has two parallel legs (54, 56) and their reflector a channel reflector (51) with two long (53) and two short (55) sides is. Luminaire according to claim 10, characterized in that the lamp is an electrodeless lamp with a closed bulb. Luminaire according to claim 11, characterized in that the piston is a loop with an oval or approximately rectangular shape. Luminaire according to claim 11, characterized in that also in the Reflective surfaces are attached near the short sides (55). Luminaire (30) with a reflector according to claim 1 and a light source, characterized in that the light source is a lamp (31), the Piston has ring shape and its reflector is rotationally symmetrical with respect to the axis of the ring.

Images