WO2011141616A1

WO2011141616A1 - A light transformer and a luminaire

Info

Publication number: WO2011141616A1
Application number: PCT/FI2010/050387
Authority: WO
Inventors: Hannu Hukkanen; Tomi Kuntze
Original assignee: Qvalo Oy
Priority date: 2010-05-12
Filing date: 2010-05-12
Publication date: 2011-11-17

Abstract

A light transformer comprises a body defining an input side, an output side, a central portion, and a peripheral portion. Within the body is a light modifier defining a longitudinal direction and a transverse direction that is locally perpendicular to said longitudinal direction. A first part of the light modifier, which is displaced from a second part of the light modifier in the longitudinal direction, is located in the transverse direction of the light modifier in relation to said second part, and at a different distance between said central portion and peripheral portion than said second part. Both the first part and the second part are configured to direct light from the input side to the output side of the light transformer.

Description

A light transformer and a luminaire

TECHNICAL FIELD

The invention concerns in general the technical field of light transformers and lu- minaires. A luminaire is an apparatus in which a light source emits light, and other structures of the apparatus serve the purpose of guiding and directing the light to obtain a desired spatial intensity pattern of light outside the luminaire. A light transformer is a part or a structure of a luminaire that actually takes part in the guiding and/or directing of light. Light sources, such as incandescent lamps, fluorescent lamps, and light-emitting diodes (LEDs), are parts that wear, for which purpose they are typically replaceable in a luminaire. A luminaire without the light source installed is frequently referred to as a light fixture or light fitting.

BACKGROUND OF THE INVENTION

A traditional trend in the lighting industry is to manufacture light sources (such as incandescent lamps, fluorescent lamps, light-emitting diodes and LED arrays) in a relatively narrow selection of standardized sizes and shapes, and to allow for the vast variety of needs, tastes, and application purposes by designing luminaires where light transformers such as lenses, reflectors, prisms and their combinations guide and direct the light that was originally emitted by the light source. Modern light sources based on LED technology place specific requirements to light transformers, because the physical region withing which the light is generated is typically very small in relation to the intensity of generated light. Additionally at least for the time being LED light sources have their characteristic radiation pattern, which is not evenly distributed in all directions. A human observer typically per- ceives a LED light source as a very bright, star-like spot of light, which can be annoying in a dark environment if the distribution of light from the LED is not moderated with a suitable light transformer.

A particular class of light transformers is collimator lenses, which are designed to collect as much of the emitted light as possible into a collimated beam that is di- rected into the direction of a central axis pointing outwards from the light source. Known solutions for collimator lenses are disclosed for example in the patent publication DE 2 201 574, published on 19 July 1973. In other cases the task of the light transformer is to distribute the emitted light as evenly as possible to some relatively wide angle, quite contrary to collimating it to any single beam. This is many time the case for example in interior lighting, where a human observer should get the impression of a sufficient, evenly distributed amount of light without any disturbing bright spots or anomalous reflections.

Other characteristics of modern light sources have also placed new challenges to the design of luminaires, light fittings, and light transformers. LEDs are extremely rugged and long-lasting, relatively cheap to produce, and draw only a minimal amount of electric current compared to e.g. incandescent light bulbs. This means that the variety and number of applications where lighting can be used has expanded dramatically, but at the same time it means that the and light transformers and light fittings should fulfil similar criteria of reduced cost, ruggedness, and capability of survival under various conditions. There exists a need for novel and innovative solutions that could meet various, sometimes even mutually contradictory requirements such as low cost, ease of manufacturing, eligibility for mass production, ruggedness, and versatility considering various needs.

SUMMARY OF THE INVENTION

According to an aspect of the invention there is provided a light transformer that has a simple, yet versatile basic structural solution, which can be modified to meet various design needs. According to another aspect of the invention there is provided a light transformer, the basic structural solution of which can be combined with different manufacturing techniques. According to another aspect of the invention there is provided a light transformer the basic structural solution can be varied to collimating and diffusing purposes according to need. According to yet another aspect of the invention there is provided a luminaire that utilizes a light transformer of the kind described above.

Advantageous objectives of the invention are achieved by using a spirally formed light modifier as a basic structural solution of the light transformer. A body that has an input side, an output side, a central portion and a peripheral portion is consid- ered to comprise a spirally formed light modifier if the light modifier defines a longitudinal direction and a tranverse direction that is locally perpendicular to said longitudinal direction, and if a first part of the light modifier, which is displaced from a second part of the light modifier in the longitudinal direction, is located in the transverse direction of the light modifier in relation to said second part, and at a differ- ent distance between said central portion and peripheral portion than said second part. Both the first part and the second part direct light from the input side to the output side of the light transformer.

In the hierarchy of concepts a light modifier is considered to be a light transformer or a part of a light transformer. As an example, a light transformer may consist completely of a spiral-shaped light modifier or it can be an integrally manufactured combination of a spiral-shaped first light modifier and a lens-shaped second light modifier. As its designation implies, a light modifier is a physical body that has a certain effect on light that passes through and/or is reflected by the light modifier. As non-limiting examples, a light modifier may keep light from passing into certain direction(s) while allowing it to freely pass into some other direction(s); it can reflect and/or refract light into some direction(s); or it may selectively absorb some wavelengths of light so that only light of particular color(s) is allowed to pass or the spectrum of the passed light is otherwise changed.

The spiral form within the light transformer has many advantages. It allows imple- menting a large variety of reflective, refractive, and other light-modifying functions in a space that does not need to be very thick between the input side and the output side of the light transformer. It allows manufacturing a significant part of the light transformer in one piece, which may help to reduce the number of individual parts that need to be assembled. With the help of form-inducing attachment parts it is possible to use a similar basic part for a variety of light transformers, so that only placing the attachment parts eventually determines the form of the light modifier. If injection moulding is used to manufacture the light transformer, the continuous spiral form allows the moulded material to fill an essential part of the mould without giving rise to unnecessary and potentially harmful internal boundaries. The exemplary embodiments of the invention presented in this patent application are not to be interpreted to pose limitations to the applicability of the appended claims. The verb "to comprise" is used in this patent application as an open limitation that does not exclude the existence of also unrecited features. The features recited in depending claims are mutually freely combinable unless otherwise ex- plicitly stated.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of spe- cific embodiments when read in connection with the accompanying drawings. Fig. 1 illustrates a light modifier in side view,

fig. 2 illustrates the light modifier of fig. 1 in top view,

fig. 3 illustrates the light modifier of fig. 1 in perspective view,

fig. 4 illustrates a light modifier in side view,

fig. 5 illustrates the light modifier of fig. 4 in top view,

fig. 6 illustrates the light modifier of fig. 4 in perspective view,

fig. 7 illustrates a light modifier in top view,

fig. 8 illustrates the light modifier of fig. 7 in perspective view,

fig. 9 illustrates the concept of a spiral form,

fig. 10 illustrates the concepts of a first part, a second part, and the associated directions,

fig. 1 1 illustrates one exemplary form of a spiral

fig. 12 illustrates another exemplary form of a spiral,

fig. 13 illustrates yet another exemplary form of a spiral,

fig. 14 illustrates yet another exemplary form of a spiral,

fig. 15 illustrates yet another exemplary form of a spiral,

fig. 16 illustrates a principle of sector-formed component spirals,

fig. 17 illustrates several light sources combined with a common light modifier, fig. 18 illustrates an array of light sources each with its own light modifier, fig. 19 illustrates a principle of interwoven component spirals,

fig. 20 illustrates a spiral-formed light modifier used for collimating,

fig. 21 illustrates another use of a spiral-formed light modifier,

fig. 22 illustrates yet another use of a spiral-formed light modifier,

fig. 23 illustrates yet another use of a spiral-formed light modifier,

fig. 24 illustrates yet another use of a spiral-formed light modifier,

fig. 25 illustrates a spiral-formed light modifier with a cross section in the form of a prism,

fig. 26 illustrates a spiral-formed light modifier with a cross section in the form of a lens section,

fig. 27 illustrates a light transformer where a protrusion constitutes a spiral- formed light modifier,

fig. 28 illustrates a light transformer where an insert constitutes a spiral-formed light modifier,

fig. 29 illustrates a luminaire with a spiral-formed light modifier,

fig. 30 illustrates a luminaire where a light transformer comprises spiral- and lens-formed light modifiers,

fig. 31 illustrates another luminaire where a light transformer comprises spiral- and lens-formed light modifiers, fig. 32 illustrates an aspect of manufacturing a light modifier in a mould, fig. 33 illustrates a spiral-formed light modifier with a dome-like support structure,

fig. 34 illustrates the use of two consecutive spiral-formed light transformers in succession,

fig. 35 illustrates assembling a light transformer with a spiral-shaped light modifier,

fig. 36 illustrates another luminaire where a light transformer comprises spiral- and lens-formed light modifiers,

fig. 37 illustrates a luminaire where a light transformer comprises a spiral- formed light modifier and a light modifier with reflective and refractive properties, and

fig. 38 illustrates a luminaire with two consecutive light modifiers. DETAILED DESCRIPTION OF THE INVENTION AND ITS EMBODIMENTS Figs. 1 , 2, and 3 are side, top, and perspective views respectively of a light modifier 101 which has the general form of a strip, band, or a flat bar wound into a circular spiral around a fictitious axis 102. The spiral extends outwards roughly in a plane that is perpendicular to the fictitious axis 102; this is seen clearly in fig. 2 which is essentially a projection of the spiral form into said plane. In the projection, each round of the spiral draws a curve that is essentially concentric with the corresponding curve drawn by the previous round but lies at a certain distance further away from the fictitious axis. The fact that the form is a spiral and not a set of concentric rings means that as the curved form of the strip, band, or a flat bar winds around the fictitious axis, the distance to the axis changes gradually and monoto- nously.

Figs. 1 and 3 show clearly that the form of the light modifier 101 is not strictly planar, but each round of the spiral is also displaced from the previous round in the direction defined by the end of the fictitious axis 102 that points downwards in fig. 1 . In other words, the central portion of the light modifier bulges slightly upwards, when the direction "up" is defined as the direction defined by the end of the fictitious axis 102 that points upwards in fig. 1 .

Figs. 4, 5, and 6 are side, top, and perspective views respectively of a light modifier 401 which otherwise resembles that illustrated in figs. 1 , 2, and 3, but the spiral form is not circular but elliptical. In other words, in the top view of fig. 5, e.g. the upper edge of the strip, band, or flat bar draws a path that is an ellipse with a con- stant incremental addition to the distance between the path and the fictitious central axis as a function of the angle rotated around the central axis.

Figs. 7 and 8 are top and perspective views respectively of a light transformer which comprises three mutually identical light modifiers. Each of the light modifiers 701 , 702, and 703 covers a 120 degrees sector around a fictitious axis 704 in a plane that is perpendicular to said fictitious axis. In its sector, each light modifier meanders outwards so that across essentially the whole width of the sector it follows a curve that is a circular arc around the fictitious axis 704, then at the edge of the sector the light modifier continues in the radial direction (from the fictitious axis 704) to a certain larger distance from the axis, after which it draws a new circular arc to the other direction across essentially the whole width of the sector, and so on.

Figs. 9 and 10 illustrate a more definite way of describing a spiral form of a light modifier in the sense of the this description. We assume that a body (not sepa- rately shown in fig. 9) defines a central portion 901 and a peripheral portion 902. Within the body there is a light modifier that has a longitudinal direction and a transverse direction that is locally perpendicular to the longitudinal direction. We note that the light modifier is not straight but curved (actually: spiral-formed), so the longitudinal direction is not rectilinear in a normal three-dimensional spatial co- ordinate system but is defined as the direction along the light modifier from its one extremity to the other. It is possible to e.g. begin at the inner end of the light modifier, follow the longitudinal direction along the winding spiral form gradually outwards from and repeatedly around the central portion, and arrive at the outer end of the light modifier. In analogy with e.g. figs. 1 to 8 we assume that the light modi- fier is essentially a spirally wound strip, band, or a flat bar, the upper edge of which is visible in the view illustrated in fig. 9.

Fictitious delimiters 903 and 904 delimit from the light modifier a first part 905 and a second part 906, which are shown enlarged and in perspective view in fig. 10. Here it is seen that the longitudinal direction defined by the light modifier at the lo- cation of the second part 906 is the tangential direction of the curved form of the second part, illustrated with arrow 1001 . In a three-dimensional coordinate system there are naturally an infinite number of transverse directions that are locally perpendicular to the longitudinal direction. In this description we are especially interested in the transverse direction in which the first part 905 is located, as looked from the second part 906. In the case of figs. 9 and 10, said transverse direction is the one illustrated with arrow 1002, whis is perpendicular to both the local longitu- dinal direction arrow 1001 and the transverse width 1003 of the strip, band, or a flat bar that constitutes the light modifier. We could also designate said transverse direction as the radial direction of the spiral form.

In fig. 9 it is easy to see that the first part 905 is displaced from the second part 906 in the longitudinal direction of the light modifier: if one begins from one of them and continues about one round, following the light modifier appropriately along the longitudinal direction all the time, one arrives at the other. Above we noted that the first part 905 is also located in the transverse (radial) direction 1002 in relation to the second part 906. It is also easy to see that the first part 905 is located at a dif- ferent distance between the central portion 901 and the peripheral portion 902 than the second part 906.

So far we have considered mainly examples where the spiral form of the light modifier follows a continuous curved path, but this not a requirement of the invention. Figs. 1 1 to 16 illustrate variations in which the spiral form of the light modifier follows different paths. In each of figs. 1 1 to 16 an example of the fictitious delimiters 903 and 904 are shown, and between them an example of first and second parts of the light modifier illustrated with a heavier line. In each exemplary case the illustrated first part of the light modifier is displaced from the second part in the longitudinal direction of the light modifier, and is located in the transverse (radial) direction of the light modifier in relation to said second part. In each case the first part is also at a different distance between the central portion and the peripheral portion than said second part.

Figs. 1 1 and 12 illustrate examples in which the spiral form of the light modifier comprises rectilinear segments and sharp bends between them. In fig. 1 1 the bends are essentially in the order of 90 degrees, which gives the spiral form a generally rectangular or square shape, depending on the lengths of the segments on different sides of the light modifier. In fig. 1 2 the bends are essentially in the order of 60 degrees, which gives the spiral form a generally triangular shape.

In fig. 13 the spiral form of the light modifier comprises rectilinear segments and bends essentially in the order of 120 degrees between them, which gives the spiral form a generally hexagonal shape. In light of figs. 1 1 , 12, and 13 the number of bends in a spiral that consists of rectilinear segments and bends can be any positive integral greater than or equal to 3. It should also be noted that not all bends need to be of the same magnitude. In fig. 14 the spiral form of the light modifier comprises both rectilinear and curved segments. In fig. 15 the spiral form of the light modifier comprises irregularly winding bends. All figs. 9, 1 1 , 12, 13, 14, and 15 are examples of structures where the light modifier circulates in at least one full round spirally around the central portion. Additionally in these examples the light modifier defines a single spiral that continues from the central portion to the peripheral portion.

As was already pointed out above with reference to figs. 7 and 8, the light modifier does not need to circulate a full round around the central portion. Fig. 16 illustrates an example of a structure where each of five different light modifiers defines a me- andering shape in a sector that covers an angle around a central axis of the light transformer. Another principle which is illustrated specifically in fig. 16, but which can also be generalised to other embodiments of the invention, is the breaking of rotational symmetry; the light transformer does not need to be rotationally symmetrical or regularly changing around the central axis. As an example in fig. 16 one of the sectors comprises a shading plate 1601 which does not let light through at all.

Matching light modifiers with multiple light sources can be done in many ways. Fig. 17 illustrates an example, in which a number of light sources 1701 are located within the central portion, and a common, spiral-formed light modifier 1702 circulates around them all. Fig. 18 illustrates another example, in which there are multi- pie light sources 1801 within the central portion, and the light transformer comprises a number of spiral-formed light modifiers 1802, each of which is centered around a different part of the central portion. If the light sources are LEDs, they can all be individual LED chips, or a multiple light source configuration may be built around a multi-chip where a number of LED chips come in a common pack- age.

Fig. 19 illustrates yet another alternative principle of utilising multiple light modifiers in a light transformer. In the example of fig. 19 the light transformer comprises two light modifiers 1901 and 1902, each of them circulating in a regular spiral around the central portion. The spiral forms of the two light modifiers (of which there could be more than two) are intertwined, so that each spiral propagates in the free space left between the rounds of the other spiral(s).

Next we will consider the utilization of the light modifiers for directing light, which as a subject is closely related to how the cross section of the light modifier looks like in the plane defined by the central axis and the transverse (radial) direction. Fig. 20 illustrates schematically an example of a light modifier used as a collima- tor. In this case the light modifier 2001 is again a spirally wound band, strip, or flat bar, and we assume that it has a reflective surface on that side that is inwards in the spiral. A cross section in a plane that contains the central axis shows how the edges of the consecutive rounds of the spiral divide the angle into which light is radiated from the light source 2002 into sectors.

If the light modifier should function as a perfect collimator, the reflective surface which the light rays "see" in each sector of the cross section should constitute a part of a parabolic line, the focal point of which coincides with the location of the light source. This condition is relatively easily fulfilled at all other parts of the struc- ture than close to the upper middle portion, where the light passes almost directly upwards in the orientation illustrated in fig, 20. If strict collimation of the light is required, it is possible to replace the innermost portion of the light modifier with an opaque portion or a collimating lens.

Depending on the width of the free space between consecutive rounds of the spi- ral, the cross section in the transverse (radial) direction of the light modifier may remain the same or it may gradually change in the collimator embodiment of fig. 20. Fig. 21 illustrates another light modifier, in which the cross section in the transverse (radial) direction of the light modifier remains the same, but a characteristic angle between the cross section of the light modifier and the central axis of sym- metry 2101 of the body changes gradually between consecutive rounds of the spiral, i.e. in the longitudinal direction of the light modifier. More exactly, in the embodiment of fig. 21 the characteristic angle of the cross section of the light modifier is at each location directed so that light propagating linearly from the light source is allowed to pass freely between the rounds of the light modifier. Even if directly emitted light is not essentially reflected from the surfaces of the light modifier in this case, it may be advantageous to use a reflector strip as the light modifier in order to create e.g. desired aesthetic effects.

In fig. 20 the form of the light modifier had been selected so that light emitted by the light source only met one side of the light modifier, so that for modifying light from the light source it was enough if the light modifier was a reflective strip with only one (inner) reflective surface. Figs. 22, 23, and 24 illustrate examples where the light modifier is a reflector strip which has two reflective surfaces on its opposite sides, of which a first side is towards the central portion and a second side is towards the peripheral portion. Depending on the width of the reflector strip, the angle between its cross section and the central axis, and the space between con- secutive rounds of the spiral, various light modifying effects may be achieved as illustrated in the drawings.

Instead of or in addition to reflectivity, the light modifier may implement refractivity. In the embodiments of figs. 25 and 26 the the light modifier is a longitudinally ex- tending refractor, and in fig. 25 it additionally defines a reflective surface that extends in the longitudinal direction of the light modifier. More exactly in fig. 25 the light modifier has a cross section in the tranverse (radial) direction that is shaped like a prism, where the outer rectilinear surface of the prism acts as a reflector, either through total internal reflection or with the help of a reflective coating on said surface. In fig. 25 the light modifier has a cross section in the transverse (radial) direction that is shaped like a lens section.

Figs. 27 and 28 illustrate the principle of implementing the light modifier as an integral part of a light transformer that has also other parts. In the example of fig. 27 the light transformer 2701 comprises a generally transparent body that defines an input side an an output side for light. The input side is downwards in fig. 27; more exactly the input side comprises a hemispherical cavity, at the lower middle point of which the light source 2702 is located. The output side is generally upwards in fig. 27. Light rays that pass almost directly upwards in the orientation of fig. 27 pass through a collimating lens portion 2703, while light rays that are emitted a bit more obliquely pass through parts of the spirally winding "fin" that constitutes the spiral-formed light modifier in the upper part of the transparent body. The outer surface of the fin may comprise a reflective coating, or the angles and indices of refraction may be selected suitably for total internal reflection, so that the spiral- formed light modifier functions essentially in the same way as the light modifier il- lustrated above in association with fig. 20.

In the example of fig. 28 the light transformer 2801 comprises a generally transparent body, into which a spirally wound reflective strip 2801 has been placed as an insert during the moulding of the transparent body. The reflective inner surface of the reflective strip makes the structure function as a collimator much like the structures of figs. 27 and 20.

Augmenting a light modifier to form a light transformer and further a light fitting or luminaire may take place in various ways. As was described earlier, a luminaire comprises a light source, which can be for example a LED light source. Additionally the luminaire comprises a light transformer, which is a body that defines an in- put side, which receives light from the light source, and an output side, to which the light is directed. Looked from the direction of the central axis, a central portion of the light transformer coincides with the location of at least one light source, and a peripheral portion is further away from the central axis. Within the light transformer body the light modifier defines a longitudinal direction and a transverse di- rection that is locally perpendicular to said longitudinal direction and that has been designated above also the radial direction. A first part of the light modifier is displaced from a second part of the light modifier in the longitudinal direction, and located in the transverse direction of the light modifier in relation to said second part. The first part is at a different distance between said central portion and peripheral portion than said second part. Both the first part and the second part are configured to direct light from the input side to the output side of the light transformer, when such light is emitted by the light source.

As an example illustrated in the cross section of fig. 29 the light modifier 2901 may be attached to a separate holder 2902, which is then attached for example by glue 2903 to a common base with the light source 2904. In the approach of figs. 30 and 31 the light modifier part 3001 , which is here shown as having support bars between the rounds of the spiral, can directly continue as an integrally manufactured holder part 3002. Another feature illustrated schematically in figs. 31 is the combination of a further light modifier part 3003 or 3101 with the spiral-formed light modifier. All these principles, i.e. having support bars between the rounds, continuing the light modifier directly into an attachment part, and combining different light modifiers into an aggregate light transformer, can be equally applied in all embodiments of the invention. If a lens is used as an additional light modifier, it does not necessarily need to be on the central axis, but a lens or lenses may be used within the peripheral portion as well.

Injection moulding is a very advantageous method for manufacturing a light modifier from transparent or translucent plastic. In order to understand the advantages of the present invention from the viewpoint of injection moulding, we may conceptually compare a spiral-formed light modifier to e.g. a light modifier that would con- sist of a set of concentric, mutually separate rings. Manufacturing the last- mentioned by injection moulding would require either producing each ring separately, or using a multitude of flow channels in the mould that would allow the molten plastic to advance from one ring-shaped cavity to another in the mould. Inevitably the molten plastic that filled a ring-shaped cavity in the mould would give rise to an internal interface where the molten plastic filling the ring-shaped cavity in the clockwise direction would meet the molten plastic filling the same ring-shaped cav- ity in the counterclockwise direction. An internal interface like that may remain visible in the final product in the form of an optical artefact, or in the worst case it may create a weak point in the structure.

A spiral-formed light modifier, on the other hand, requires only one, spiral-shaped cavity in the mould. Molten plastic may advance smoothly from one end to the other end of the spiral-shaped cavity without giving rise to similar internal interface problems as in the case of separate, concentric rings. This means that the invention enables manufacturing light modifiers of high optical quality and mechanical strength. Fig. 32 illustrates another aspect of manufacturing a spiral-formed light modifier by injection moulding. It is advantageous from the manufacturing point of view if the mould comprises as few parts as possible. In this case the mould comprises an upper half 3201 and a lower half 3202, and the form of the light modifier is such that each obliquely oriented surface of it is either entirely accessible from above or entirely accessible from below. This way the completed workpiece can be removed from the mould simply by pulling the halves of the mould open in the vertical direction. Naturally the invention does not exclude the use of more complicated moulds as well.

Fig. 33 illustrates an exemplary principle of having a spiral-formed light modifier 3301 supported from the input side by a transparent dome 3302. As an alternative or addition, a transparent dome could be used also on the output side of the light modifier. Fig. 34 illustrates schematically the principle of using two (or more) spiral-formed light modifier in succession so that the output side of one of them faces the input side of the other. Fig. 35 illustrates a possibility of finalizing the form of the light transformer only at the assembly stage, so that a light modifier is made of a flexible reflector strip 3501 which is attached to a base 3502 in a desired spiral form. The assembler of the light transformer may select separators 3503 of desired form to match the desired profile of the empty space between rounds of the spiral, and attach them to desired locations in the base 3502 so that the separa- tors force the flexible reflector strip to the desired angle at each location.

Fig. 36 illustrates a luminaire where a spiral-formed light modifier 3001 continues directly into a holder part 3002, which is additionally configured to hold a lens 3601 which is located between the light source 3602 and the spiral-formed light modifier 3001 . This example further confirms the earlier statement that in a light trans- former according to an embodiment of the invention that combines two light modi- fiers, the order and mutual arrangement of the light modifiers is not limited by the invention. Merely, the selection, order, and mutual arrangement of the light modifiers will be determined for each case separately, using the desired three- dimensional distribution of output light as a starting point. Reflective and/or refractive light modifiers can be combined so that their combined effect in modifying the distribution of the emitted light is carefully designed. Figs. 37 and 38 illustrate examples of luminaires where the emitted light is first modified by a reflective light modifier (which in fig. 37 has partially also refractive properties) and thereafter by a reflective spiral-formed light modifier. Some exemplary light rays are shown in the drawings to illustrate the second- and higher order reflections that constitute the eventual observable output.

In general, with light transformers and luminaires according embodiments of the invention, the pattern of output light may be rotationally symmetric around the central axis, or it may be asymmetric, or it may change as a function of the angle around the central axis, or it may in principle have any desired shape. Especially b combining light modifiers, but also in some cases by using only a single light modifier, it is possible to ensure that a human observer will not directly see the light source from any direction from which he or she will be looking at the luminaire under its normal operating conditions. In other cases it may be ensured that there is a direct path out from the light source in some directions, while there are other directions from which the light source must not be visible. It is possible to controlla- bly change the distribution of output light by changing the spatial relations of the different parts in the luminaire, including different light modifiers in those cases where multiple light modifiers are included. Even with a single light modifier it is possible to controllably change the distribution of output light by changing the dimensions, directions, and reflective and/or refractive characteristics of different parts of the light modifier.

Claims

1 . A light transformer, comprising:

- a body defining an input side, an output side, a central portion, and a peripheral portion, and

- within the body, a light modifier defining a longitudinal direction and a transverse direction that is locally perpendicular to said longitudinal direction;

wherein a first part of the light modifier, which is displaced from a second part of the light modifier in the longitudinal direction, is located in the transverse direction of the light modifier in relation to said second part, and at a different distance be- tween said central portion and peripheral portion than said second part,

and wherein both the first part and the second part are configured to direct light from the input side to the output side of the light transformer.

2. A light transformer according to claim 1 , wherein the cross section in the transverse direction of the light modifier remains essentially similarly shaped be- tween the first and second parts of the light modifier.

3. A light transformer according to claim 1 , wherein the cross section in the transverse direction of the light modifier changes gradually between the first and second parts of the light modifier.

4. A light transformer according to claim 2 or 3, wherein a characteristic angle between the cross section in the transverse direction of the light modifier and a central axis of symmetry of the body changes gradually between the first and second parts of the light modifier in the longitudinal direction of the light modifier.

5. A light transformer according to any preceding claim, wherein the light modifier is a reflector strip.

6. A light transformer according to claim 5, wherein the reflector strip has exactly one reflective surface.

7. A light transformer according to claim 5, wherein the reflector strip has two reflective surfaces on its opposite sides, of which a first side is towards the central portion and a second side is towards the peripheral portion.

8. A light transformer according to any of claims 1 to 4, wherein the light modifier is a longitudinally extending refractor.

9. A light transformer according to claim 8, wherein the light modifier additionally defines a reflective surface that extends in the longitudinal direction of the light modifier.

10. A light transformer according to any preceding claim, wherein the light modi- fier circulates in at least one full round spirally around the central portion.

1 1 . A light transformer according to claim 10, wherein the light modifier defines a single spiral that continues from the central portion to the peripheral portion

12. A light transformer according to any of claims 1 -9, wherein the light modifier defines a meandering shape in a sector that covers an angle around a central axis of the body.

13. A light transformer according to any of claims 1 -9, wherein the light transformer comprises a number of light modifiers, each of which is centered around a different part of the central portion.

14. A light transformer according to any preceding claim, comprising a holder configured to hold the body in place in relation to a base.

15. A light transformer according to any preceding claim, comprising an attachment part for attaching an auxiliary light transformer to the light transformer.

16. A luminaire, comprising:

- a light source,

- a body defining an input side facing said light source, an output side, a central portion, and a peripheral portion, and

wherein a first part of the light modifier, which is displaced from a second part of the light modifier in the longitudinal direction, is located in the transverse direction of the light modifier in relation to said second part, and at a different distance between said central portion and peripheral portion than said second part,

and wherein both the first part and the second part are configured to direct light emitted by said light source from the input side to the output side of the light trans- former.