WO2005106323A1

WO2005106323A1 - Variable colour lighting

Info

Publication number: WO2005106323A1
Application number: PCT/DK2005/000295
Authority: WO
Inventors: Mogens Davidsen
Original assignee: Martin Professional A/S
Priority date: 2004-04-30
Filing date: 2005-04-29
Publication date: 2005-11-10

Abstract

The present invention relates to an apparatus for variable colour lighting comprising at least two light sources connected to means for regulation, which means for regulation are connected to said central control unit and where the apparatus further comprises at least one said rear reflector. The object of the invention is to provide a method and luminary with a high degree of mixing of light within a relatively small volume and to provide the mixed light at one or more exit surfaces of relatively small dimensions. This might be achieved if the apparatus comprises at least one side reflector and one front diffuser, partly reflective and partly transmitting, where the front diffuser is reflecting a portion of light back towards the light sources, where further a portion of light is transmitted through the front diffuser. Hereby, it is achieved that the mixing of colour of light is improved and appears more uniform. When light is reflected back into the enclosure the travelling of the light is extended and the mixing of colour of light is increased.

Description

Variable colour lighting

FIELD OF THE INVENTION

The present invention relates to an apparatus for variable colour lighting comprising at least two light sources connected to means for regulation, which means for regulation are connected to a central control unit. The apparatus further comprises at least one rear reflector.

The present invention also relates to a method for mixing of light generated from at least two light sources, which light sources are controlled by electrical regulation means, where emitted light is reflected from a rear reflector.

BACKGROUND OF THE INVENTION

A light-mixing luminary mixes light from two or more light sources and emits the mixed light at exit apertures or surfaces.

Mixing of light is particularly useful for three light sources of the three basic colours of light, red, green and blue. In combination with regulation of the light output of each of the light sources individually, coloured light may be provided in all combinations of the three basic colours.

Mixing of light is generally incomplete in the sense that a variation of the proportions of contributions from the light sources may occur with the location at the exit aper- tures or surfaces or with the directions in space.

In the case of mixing colours of light, incomplete mixing may be observed with the location at the exit apertures or surfaces and/or with the direction of observation. Incomplete mixing of light is undesirable for most applications, where the exit apertures or surfaces should appear with a uniform colour of light, or where the illumination of the exterior should be of a uniform colour of light. Incomplete mixing of light may be most clearly visible when the exit apertures or surfaces are equipped with additional optics, such as reflectors or louvers, intended to direct or control the emitted light. Some light mixing luminaries are intended to be used with different additional optics depending on the illumination application, to make them versatile in view of several illumination applications. For such light mixing luminaries, incomplete mixing is particularly undesirable.

As light mixes in a natural way over distance, one method of improving the mixing of light is to make a light-mixing luminary sufficiently large in view of the intended degree of the mixing. However, for most applications it is a disadvantage that the luminary is large. This applies in general for luminaries intended to be used with additional optics, as the dimensions of the additional optics must be increased in scale with the dimensions of the exit apertures or surfaces of the luminary.

There are various forms of variable colour luminaries described in the patent literature. A variable fluorescent lighting is described in US 6,062,706. This invention has a plurality of fluorescent lighting devices in close proximity of each other located near the focus point of a curved reflector. The fluorescent devices are selectively dimmed which makes it possible to produce a desired colour with a brightness desired.

This invention has a drawback when it is observed at the exit of the aperture, which makes it possible to observe the fluorescent devices directly, and the mixing of the colours of light is not satisfactory. The target, which is hit by the light might be col- oured in a non uniform pattern if the target is close to the aperture.

WO 03/071185 describes a luminaire comprising at least two lamps and a light- reflecting surface reflecting the light from said lamps. The lamps radiate light with different colours. The intensity of the light shining from a lamp can be reduced in or- der to vary the colour of the light. The light shines through a diffuser plate forming the front side of the luminaire. A light curtain plate is located between the lamps and the diffuser plate. The light curtain plate contains light reflecting material. The luminaire described above is using as well a diffuser plate and a light curtain to achieve multi reflections of the lamps between the light curtain and the back or side reflector. Also between the light curtain and the diffuser plate are generated multire- flections of the light before some of the light is transmitted through the diffuser plate. The light has to pass through both the light curtain and the diffuser plate, which in combination of the multi reflections reduces the light output compared with the power consumption of the luminare.

The object of the invention is to provide a method and luminary with a high degree of mixing of light within a relatively small volume and to provide the mixed light at one or more exit surfaces of relatively small dimensions.

This might be achieved if the apparatus comprises at least one side reflector, where the apparatus further comprises at least one front diffuser, which front diffuser is ^"partly reflective and partly transmitting, where the front diffuser is reflecting a portion of light back towards the light sources, where further a portion of light is transmitted through the front diffuser.

Hereby, it is achieved that the mixing of colour of light is improved, and it appears more uniform when observed from the outside. The incident light on the front diffuser is either reflected back into the enclosure or transmitted through the front diffuser. When light is reflected back into the enclosure, the travelling of the light is extended and the mixing of colour of light is increased. A high degree of mixing of light from the light sources is obtained by substantial and repeated reflection of the light within the enclosure - normally called inter-reflection. The light that passes through the front diffuser is therefore a mix of direct light from the light sources and reflected light from the rear reflector and side reflectors. This makes it possible to decrease the size of the luminary and still obtain a good mixing of the colour of light.

In a further preferred embodiment, the side reflector and the rear reflector are integrated in the same part. Hereby, it is achieved that both reflective components are formed in the same part. This part could be a high reflective metal sheet placed over and around the light sources. In a further preferred embodiment, the side reflector has a curved shaped reflecting surface. Hereby, a greater spread of the reflecting light is achieved which results in a more uniform mixing of colour of light.

In a further preferred embodiment, the side reflector is a convex shaped reflecting surface. Hereby, a greater spread of the reflecting light is achieved which results in a more uniform mixing of the light.

In a further preferred embodiment, the side reflector is a concave shaped reflecting surface. Hereby, a greater spread of the reflecting light is achieved which results in a better mixing of colour of light.

In a preferred embodiment, at least either the side reflector or rear reflector is reflect- ing by diffusion material. Hereby, it is achieved that the incident light is reflected in all directions, which results in further inter-reflection of the light and better mixing of colour.

In a further preferred embodiment, the apparatus comprises a further second side re- flector attached to the front diffuser. Hereby, a further mixing of the light at the aperture is achieved.

In a further preferred embodiment, the apparatus comprises a front diffuser, which is partly reflecting and partly transmitting by diffusion. Hereby, a further mixing of the directions of the transmitted light is achieved.

In a further preferred embodiment, the apparatus comprises an optical lens, which is attached to the said front diffuser. Hereby, a further mixing of the light is achieved.

The invention also concerns a method where the emitted light is reflected by at least one side reflector towards the inner space of an enclosure, where a front diffuser reflects a first portion of light backwards, and where the front diffuser transmits a second portion of light. Hereby, it is achieved that the light from the light sources is effectively mixed inside the enclosure, and a uniform light is generated.

SHORT DESCRIPTION OF THE DRAWINGS

The invention will be explained in more detail with reference to the drawing, where

fig. 1 shows a cross-section of the invention with three light sources and a front diffuser, fig. 2 shows a cross-section of a side reflector with a curved mirror type surface, fig. 3 shows a cross-section of a side reflector with a convex mirror type surface, fig. 4 shows a cross-section of a side reflector with a concave mirror type surface, fig. 5 shows a cross-section of a side reflector with a diffusing surface, fig. 6 shows a cross-section of an alternative embodiment of the invention with a second side reflector attached to the front diffuser, fig. 7 shows a cross-section of the front diffuser with an optical lens attached to it, fig. 8 shows a cross-section of an optical lens attached to the second side reflector, and fig. 9 shows a cross-section of a third alternative embodiment for the invention.

DETAILED DESCRIPTION / PREFERRED EMBODIMENT

Fig. 1 shows a cross-sectional view of the invention comprising an apparatus 2 which apparatus 2 comprises three light sources 4,6,8 placed in a housing 48. The lamps

4,6,8 are via wiring 58,60,62 connected to dimmer units 10,12,14. Each of the dimmer units 10,12,14 are via wiring 52,54,56 connected to a control unit 16, which is connected by a wiring 50 to the surroundings. The housing 48 further comprises a rear reflector 18, which is connected with a side reflector 20. The front diffuser 22 is fur- thermore connected to the side reflector 20.

Fig. 1 shows a cross-section of the invention with three light sources 4,6,8 contained within an enclosure 48 formed of a rear reflector 18 and a side reflector 20 with high internal reflectance, and with one front diffuser 22 partly transmitting 72 and reflecting 80 the incident light. The light sources 4,6,8 may for instance be fluorescent tubes of the primary colours of light, red, green and blue. The front diffuser 22 maybe plates of for instance opal plastic, opal glass or partly perforated metal plate. Opal plastic plates may for instance be of commercially available types with a reflectance of 60 % to 80 % and a transmittance of almost the remainder of 100 %. The front diffuser 22 may posses a direct or a diffuse type of transmission. It is advantageous for further mixing of the directions of the transmitted light that at least some diffusion takes place during the transmission.

Fig. 2 shows a cross-section of a side reflector 120 deferring from the front diffuser 20 in that the front diffuser 120 is curve shaped.

By the curve shaped side reflector 120, it is achieved that light falling on the surface is reflected in different directions, and a multi reflection of the light is achieved which could lead to a very effective colour mixing.

Fig. 3 also shows a cross-section of a side reflector 124, which is formed with a convex surface.

Fig. 3 shows the invention with a convex side reflector forming the enclosure to provide a narrowing of the path from the light sources to the front diffuser. This improves the mixing of the light at the front diffuser. The invention may be used with or without these indentations; when used with indentations these are best formed in surfaces with mirror type reflection.

Also a side reflector 124 with a convex surface reflects incoming light in different directions, which leads to an effective mixture of the three different colours coming from the light sources placed above.

Fig. 4 shows a cross-section of a side reflector 126 which reflector 126 is concave. The concave form of the side reflector 126 also leads to an effective mixture of the light.

Fig. 5 shows a side reflector 128 which reflector 128 is a diffusion reflector.

The diffusion reflector 128 also leads to an effective colour mixture in that the light is reflected back in different directions.

Fig. 5 shows a cross-section of the invention with a second side reflector attached out- side the front diffuser as shown on the figure. The purpose is to further increase the mixing of the light by reflecting the incident light. It is also possible to attach the front diffuser with optics such as reflectors or louvers to direct or control the emitted light.

Fig. 6 shows a sectional view of an alternative embodiment of the invention. Fig. 6 partly shows the same embodiment as fig.l where the numbering in the drawing for equal elements is added with 200, and the numbers on fig. 6 which have already been described in connection with the description of fig. 1 are not further described.

Fig. 6 differs from fig. 1 in that a further side reflector 232 is connected to the front diffuser, and a further reflection takes place at this reflector 232. Also the front diffuser 222 is here shown differently in that it is a diffusion reflector which reflects up to 50 % of the light back towards the inner walls of the housing, and only approximately 50 % of the light is led through the diffusion reflector, and further at the sur- face downwards of that reflector, further diffusion material may exist. This leads to an extremely good colour mixing, and a further effect of the side reflector 232 is that the direction of the light coming from the apparatus 202 is directed downwards and not in a direction inside the apparatus. Fig. 6 shows the front diffuser 222 which has a diffuse type of transmission resulting in the incident light to be transmitted and reflected into various directions 272. The side reflectors 220 and the rear reflector 218 forming the enclosure 248 may have either a diffuse or a mirror type reflection 270, or a mixture of the two. The figure shows an incident light ray 268 reflected on a mirror type rear reflector 218, and another incident light ray 270 is reflected by diffuse reflection on the side reflector 220. It is advantageous that some of the reflectors have a mirror type reflection in order to transport light from the light sources 204,206,208 to the front diffuser 222. Reflectors 218,220,222 with a diffuse type of reflection may have coatings of for instance white paint. Surfaces with a mirror 218,220 type reflection may for instance have coatings of aluminium covered by further coatings in order to protect the aluminium layer or to enhance the reflection. Reflectance values of 85 % up to 95 % can be obtained with commercially available coatings. As an alternative the rear and/or side reflectors might be formed of glass having transmitting and/or reflecting coating. The rear and /or side reflectors might be transmitting infra red light and reflecting viewable light. Hereby can the light that leaves the lamp contain only a small amount of infra red light.

Fig. 7 shows a sectional view of the front diffuser 222 with lens formed elements 236 placed under the front diffuser. These front lenses 236 further lead to a mixture of the light. Fig. 7 shows that the diffusion may be applied with one ore more optical lenses

236 attached to the outer side of the front diffuser 222.

Fig. 8 shows a sectional view of a further embodiment here showing the front diffuser 222 connected to the side reflectors 232 where the front glass is placed below the side reflectors 232. This front glass 238 further comprises lens elements. These lens elements are shown in an upward direction but could in another embodiment be pointing downwards and shaped differently.

Fig. 9 shows a cross-section of an alternative embodiment for the invention with a circular enclosure 348 and a circular front diffuser 322. The side reflector 320 and the rear reflector 318 are attached to the enclosure in such a way that it forms a circumferential surface of reflecting material. Hereby, it is achieved that the reflected light is directed towards the inner of the enclosure. The rear reflector 318 may advantageous be of a mirror type reflector and the side reflector may be of a diffusing material, which reflects all the light 370 in different directions. The front diffuser 322 is shown as a circular component but could be a plan as shown in the previous figures. Fig. 10 shows a cross section of a further alternative embodiment for the invention showing an alternative light reflector 424 which reflector 424 has a convex surface at least in the area below the lamps 406, 408. Over and beside the lamps 406, 408 are a back and side reflector 418 which back and side reflector 418 is connected to the re- flector 424 with the convex surface. Connected to the reflectors 424 is shown a front diffuser 422. This figure also shows electrical control means 410. 412 and 414.

The convex side reflector 424 is the most efficient way of reflecting the light coming from the lamps 406, 408 and for achieving an ideal colour mixing. If other geometric forms for the side reflector 424 is used, there might be a relatively bad colour mixture where one of the lamps 406, 408 has dominance in the light that passes through the front diffuser 422.

The picture 11 shows an alternative embodiment to Fig. 10 with the only difference that the light sources 506 and 508 are placed inside colour filters 507 and 509.

Hereby is achieved that the light sources 506, 508 can be emitting white light and the colours are generated by the filters 507 and 509.

Fig. 12 shows a sectional view of a further possible embodiment for the invention showing light sources 606 and 608 placed inside filters 607 which are fixed to the back reflector.

Also in this way white emitting light sources could be used.

Fig. 13 shows a sectional view of a possible embodiment for the invention where light sources 706 and 708 are placed inside cavities 710 formed in the back reflector. These cavities 710 are covered by filters 707. Also in this possible embodiment for the invention white emitting light sources could possibly be used, and colours are generated by the filters 707.

The fig. 14 shows a section view of a practical embodiment for the invention. A lamp unit 802 is supported by a basic module 816 which contains the electronic control cir- cuits are connected to a wall 815 where the basic module by connecting means 817 are connected to the lamp 802 itself.

Both the basic module 816 and the lamp 802 comprise means for moving the lamp. Moving the lamp 802 can take place by manual activation but it is also possible to use activators which are driven from an external energy source. The activators could be electrical, pneumatic or hydraulic. The lamp 802 comprises light sources 806 and 808 placed inside a reflecting housing 818 connected to a side reflector 824 covered by a reflective front glass 822 which reflects parts of the light backwards to the back reflec- tor 818. Below the front reflector 822 is shown further reflective means at the sides 852 and at the bottom there is a front glass 854 covering the lamp. In side the lamp and below the front glass 822 is shown further a light source 850 which light source generates white light.

The use of a fixture 816 which is connected to the lamp means that the lamp 802 could be turned in its direction manually or automatically. Further, the use of the extra light source 850 means that a lamp of this type is highly efficient in generating white light. In practice white light from the light sources 806 and 808 is possible if e.g. three light sources each are reduced to approximately 50%. Then the light efficiency that is gen- erated will be reduced to approximately half of the light effect that should be possible

By using the extra white light source 850 and maybe even controlling this light source, bright white light can be generated. The white light can be manipulated by adjusting the colour by influencing the light sources 806 and 808. In this way the generated light coming out of the front glass 854 can be adjusted from a hard white containing rela- tively much blue light into a soft white containing more red light.

Claims

1. Apparatus (2, 202, 302) for variable colour lighting comprising at least two light sources (4, 6, 8, 204, 206, 208, 304, 306, 308) connected to means for regulation (10, 12, 14, 210, 212, 214, 310, 312, 314), which means for regulation (10, 12, 14, 210,

212, 214, 310, 312, 314) are connected to a central control unit (16, 216, 316) the apparatus^, 202302) further comprises at least one rear reflector (18,218,318) char acterisedin that the apparatus (2, 202, 302) comprises at least one side reflector (20, 120, 124, 126, 128, 220, 320) where the apparatus (2,202, 302) further comprises at least one front diffuser (22, 222, 322), which front diffuser (22, 222, 322) is partly reflective and partly transmitting, where the front diffuser (22, 222, 322) reflects a portion of light back towards the light sources (4, 6, 8, 204, 206, 208, 304, 306, 308), where a portion of light is further transmitted through the front diffuser (22, 222, 322).

2. Apparatus according to claim 1 characterisedin that the rear reflector (18, 218, 318) and the said side reflector (20, 220, 320) are integrated in the same part.

3. Apparatus according to one of the claims 1 or2characterisedin that the said side reflector (20, 220, 320) is a curve shaped reflecting surface (120).

4. Apparatus according to one of the claims 1 or2characterisedin that the said side reflector (20, 220, 320) is a convex shaped reflecting surface (124).

5. Apparatus according to one of the claims 1 or2characterisedin that the said side reflector (20, 220, 320) is concave shaped reflecting surface (126).

6. Apparatus according to one of the claims 1 or2characterisedin that the said side reflector (20, 220, 320) is reflecting by diffusion material (128).

7. Apparatus according to any of the claims l-6characterisedin that the apparatus (2, 202, 302) comprises a further second side reflector (232) attached at the front diffuser (222).

8. Apparatus according to any of the claims 1-7 characterised in that the front diffuser (22, 222, 322) which is partly reflecting by diffusion and which is partly transmitting by diffusion.

9. Apparatus according to any of the claims 1-6 characterised in that the apparatus (2.202, 302) comprising at least one optical lens attached to the front diffuser (22, 222, 322).

10. Method for mixing of light generated from at least two light sources (4, 6, 8, 204,

206, 208, 304, 306, 308), which light sources (4, 6, 8, 204, 206, 208, 304, 306, 308) are controlled by electrical regulation means (10, 12, 14, 210, 212, 214, 310, 312, 314), where emitted light is reflected from a rear reflector (18, 218, 318), c h a r a c t e r i s e d in that the emitted light is reflected by at least one side reflector (20, 120, 124, 126, 128, 220, 320) towards the inner space of an enclosure (48, 248, 348), where a front diffuser (22, 222, 322) is reflecting a first portion of light backwards, and where the front diffuser (22, 222, 322) is transmitting a second portion of light.