Patent Application
20120182764
The present invention relates to a lighting system, and, more particularly, to a lighting system capable of providing diffuse, glare free lighting in an indoor environment. The lighting system has the further capability of limiting illumination to some areas of this indoor space as selected by a user.
Artificial light sources, from the candle to the incandescent bulb to LEDs, tend to be highly localized point sources. There are a few exceptions—fluorescent tube lighting being an obvious example—but even in these cases the light source is confined to a relatively small volume. These light sources can be highly directional, such as spot lighting, and designed to emit into a narrow cone angle. Alternatively, as is the case for traditional incandescent filament lights or cold cathode fluorescent lights (CFLs), the emission is much closer to isotropic, with very little directional or angular control. In either case, emission from a relatively small source can cause problems with glare, either directly if the light source is within the field of view of an observer, or indirectly through reflections off other surfaces. Reflections from TVs, for example, can make the display difficult to see and spoil the viewing experience. Similarly, point sources can cast strong shadows, which can be aesthetically displeasing and leave some areas in an environment in shadow, thus making objects hard to see.
Some prior art has already tried to address aspects of the limitations above.
Ser. No. 05/386,353 (Dominic Battaglia, Jan. 31, 1995) discloses surface mounted lighting units, comprising light source, housing 10, and cover 11 (see
JP24349165 (Matushita Electric Works Ltd., Dec. 9, 2004) discloses an indirect light source designed for a cornice, illustrated in
WO09504897 (Neon and Cathode Systems, Feb. 16, 1995) discloses a modular cove lighting system which uses fluorescent tubes 30 within a housing 31, as shown in
Another solution to reduce glare is to illuminate a large area indirectly, by projecting light from a smaller source. An example of this type of system could be a LED light source with optics such that it becomes side emitting into a narrow angular range.
US07524098 (Dicon Fibreoptics ltd., Apr. 28, 2009) discloses a side emitting optic element for an LED light source 40, as shown in
Ser. No. 06/607,286 (Lumileds lighting US, Aug. 19, 2003) discloses another example of a side-emitting optic element for an LED light source 50, as shown in
As is shown, examples of side emitting LEDs in the prior art are known. However, these side-emitting LEDs are designed for in-coupling to backlights or light guides, and are therefore designed with rather different criteria in mind. A major difference to the ideal side-emitting light source for projection lighting is the angle into which light is emitted; for a projection source the angular range should be as narrow as possible, whereas for in-coupling to a backlight a larger spread of angles is required in order to facilitate extraction from the backlight.
The prior art outlined above still leaves significant scope for improvement in indoor lighting. There is extremely limited control over the direction of illumination, and thus which areas should be illuminated. As well as limiting a users' control over the lighting conditions in a room this is also inefficient, since light is wasted through illuminating areas where it is not needed or wanted.
There are problems with existing lighting systems, as described in the background section, which include issues with glare from small point or narrow line sources; strong shadowing from the same; lack of control over lighting directionality, and reduced efficiency caused by emitting light into directions where it is not needed. Side emitting sources in the prior art are not ideal for projection lighting because they are designed to emit into a relatively wide angular range, as is necessary for in-coupling and subsequent extraction in lightguides.
The present invention provides a lighting system which is able to improve issues with conventional light sources by introducing a method of providing light to a room from a cornice or equivalent location near the upper part of walls. Subsequently this area will be referred to as the cornice, but refers to the same location whether or not a cornice molding is present. The lighting system in accordance with the invention includes directional control such that light can be transmitted from some parts of the cornice but not all. The emission of light from the cornice may be achieved either directly from a light source positioned at that location, or by projecting light from another point in the room such that it reflects off the cornice.
Advantages of such a system are multiple; to achieve the same light levels in the room as from a single point source, the illuminance around a cornice can be much lower, hence the light source is more comfortable to look at and problems with glare are greatly reduced or eliminated. A light source from multiple locations will also greatly reduce shadowing.
By providing directional control, light levels in various parts of a room can be adjusted to give optimum brightness in each, and the efficiency of the lighting system will be increased through the reduction of wasted light. Further advantages include the fact that light sources designed to project light towards the cornice can also be retrofitted in many locations since ceiling lights are often fitted in the centre of a room, and could easily be replaced with a projection light source.
According to one aspect of the invention, a lighting device for lighting an area includes: a strip illuminating structure for distributing light from respective sections thereof; and a light source controllable to selectively provide the light to the sections.
According to one aspect of the invention, at least two sections of the strip illuminating structure are configured to distribute light in a direction different from one another.
According to one aspect of the invention, the strip illuminating structure comprises a light guide including at least one light receiving surface and a light exit surface, and the light source comprises at least two light emitting devices in-coupled to the at least one light receiving surface.
According to one aspect of the invention, the light guide comprises a plurality of extraction features configured to extract light from the light guide in one or more predetermined directions.
According to one aspect of the invention, the light source comprises an optic configured to project light having a predetermined beam direction.
According to one aspect of the invention, the optic is a side-emitting optic having an optical axis arranged parallel to the light exit surface, the optic including: a light receiving surface; a collimating surface arranged between the light receiving surface and the light exit surface; and a reflective surface configured to reflect light received at the light receiving surface into a predetermined range of angles relative to a plane perpendicular to the optical axis.
According to one aspect of the invention, the reflective surface is at least one of a totally internally reflecting surface, a metallic surface or a mirrored surface.
According to one aspect of the invention, the light source is configured to provide an illumination pattern through refraction.
According to one aspect of the invention, the optic includes a plurality of optics.
According to one aspect of the invention, a totally internally reflective surface of the optic is circularly symmetric.
According to one aspect of the invention, the light source comprises a scanning mirror, and the lighting device further comprising a controller configured to control a position of the scanning mirror.
According to one aspect of the invention, the light source further comprises a plurality of light emitting diodes (LED) and a plurality of scanning mirrors, each LED of the plurality of LEDs corresponding to one scanning mirror of the plurality of scanning mirrors.
According to one aspect of the invention, a method for lighting an interior space having at least one wall and a ceiling adjacent to the wall, the at least one wall and ceiling forming at least one corner portion includes: using a strip illuminating structure to provide light to the at least one corner portion; and controlling a light source to selectively distribute the light from sections of the strip illuminating structure.
According to one aspect of the invention, controlling includes controlling the light source to distribute light from two sections of the strip illuminating structure in directions different from one another.
According to one aspect of the invention, providing light to the at least one corner portion includes placing the light source in the at least one corner portion.
According to one aspect of the invention, providing light to the at least one corner portion includes projecting light into one or more predetermined sections of the strip illuminating structure.
According to one aspect of the invention, controlling the light source includes controlling at least two light sources.
According to one aspect of the invention, the method further includes selecting a length of the light source to correspond to a length of the wall.
According to one aspect of the invention, the method further includes placing the light source on the ceiling a predetermined distance from the at least one wall.
According to one aspect of the invention, controlling the light source includes controlling at least two light sources, a first light source of the at least two light sources positioned on the ceiling and a second light source of the at least two light sources positioned at the cornice.
According to one aspect of the invention, placing the light source on the ceiling includes placing the light source in a center of the ceiling.
According to one aspect of the invention, the method further includes arranging the light source to illuminate at least a portion of the ceiling so as to reflect light from the ceiling into the interior space.
According to one aspect of the invention, the method further includes projecting light from the at least one light source toward the cornice, and reflecting the projected light from the cornice into an area of the interior space.
According to one aspect of the invention, the method further includes using a reflective sheet at the cornice to reflect the projected light from the cornice.
According to one aspect of the invention, using a reflective sheet includes using a reflective sheet that reflects light using at least one of mirror surfaces or total internal reflection.
According to one aspect of the invention, the method further includes placing the light source remote from the cornice, and using a scanning mirror to project light toward the cornice.
According to one aspect of the invention, the method further includes collimating the light prior to projecting the light toward the cornice.
According to one aspect of the invention, controlling the light source includes using a light source comprising a light guide as the light source, said light guide having at least one input surface for receiving light and an exit surface for emitting the received light;
According to one aspect of the invention, the method further includes configuring the exit surface of the light guide to compensate for fall-off intensity proportional to cost.
According to one aspect of the invention, controlling the light source includes using extraction features having a prism-based geometry to control a direction of light emitted by the light source.
According to one aspect of the invention, using extraction features includes arranging the extraction features such that a feature density in a given area corresponds to a distance of the extraction features from the at least one input surface.
According to one aspect of the invention, controlling the light source includes using a pre-existing light source in the interior space.
According to one aspect of the invention, the method further includes controlling an emission brightness from portions of the light source to control an illumination pattern in the interior space.
To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative embodiments of the invention. These embodiments are indicative, however, of but a few of the various ways in which the principles of the invention may be employed. Other objects, advantages and novel features of the invention will become apparent from the following detailed description of the invention when considered in conjunction with the drawings.
In the annexed drawings, like references indicate like parts or features:
a illustrates one option for improving the optic to correct for cos4θ illumination pattern, viewed from the side.
b as
a illustrates an exemplary geometry for a directionally specific ceiling illuminating optic.
b illustrates the optic shown in
The present invention provides a device and method for lighting an area, such as an interior space (e.g., a room having walls and/or a ceiling). In accordance with the invention, a strip illuminating structure distributes light from respective sections of the structure, and a light source is controlled to selectively provide the light to the sections of the structure. The strip illuminating structure and/or light source can be configured such that light from two different sections of the strip illuminating structure are distributed in different directions. The strip illuminating structure can include a light guide having at least one light receiving surface (e.g., a surface that receives light from a light source) and a light exit surface, e.g., a surface from which light is emitted. The light source can include a light generation device that is selectively switchable to control the emission of light. For example, the light generation device may be configured to be selectively switchable such that light emitted from the device is output from part but not all of the light exit surface. In this manner, directional control of the light emitted from the light exit surface is achieved, thereby enabling a target illumination level to be achieved in the interior space. Further, the strip illuminating structure and/or one or more light sources may be configured such that light emitted by respective light sources is in-coupled to respective light receiving surfaces of the light guide.
A preferred embodiment of an exemplary lighting system in accordance with the present invention is illustrated in
In this preferred embodiment the room or other indoor space is illuminated by one or more lightguides, as illustrated in
The combined lightguide length 74 per wall should be sufficient to substantially span the length of each wall, and the preferred embodiment uses one light guide per wall. For example a wall 3 m in length would use a lightguide slightly less than 3 m long, allowing sufficient space for the one or more light sources and fittings at both ends. The lightguides in this embodiment are located at a predetermined section of the room, such as at the position where a cornice would be found, around the join between the walls and ceiling in a room. The width 73 is similar to that of a typical cornice molding—10-15 cm. The lightguide thickness 75 will be controlled by the size of the light source, but should be no more than about 1 cm, and preferably less; sufficient to allow efficient in-coupling from the light source. The lightguides preferably are made of a transparent material such as PMMA.
Light is in-coupled into the lightguide from the light sources, and propagates through the lightguide by total internal reflection (TIR). TIR is frustrated by extraction features 71 within the lightguide, thus providing illumination to the room or other space. The extraction features are designed to extract light with a specific (predetermined) angular direction 72, for example, perpendicular to the length of the lightguide. By controlling the angle at which light is out-coupled from the light guide, a specific area in a room may be illuminated by having one part of a light guide illuminated. Thus, a user may choose to have some parts of the room lit whilst leaving others dark. Extraction features which achieve this angular control over extraction direction could have, but are not limited to, prism-based geometry. An example of this is triangular cross-section prisms arranged along the width of the lightguide, as shown in
The extraction features may be arranged such that extraction is uniform over the whole or part of the length of the lightguide, thus using a higher density of extraction features further from the source. If the lightguide is illuminated from both ends the extraction features, the extraction features are symmetric about the centre of the lightguide. In this case, the extraction feature density may be designed such that, by illuminating only one end of the lightguide, light is extracted only from the near half of the lightguide. In this way, substantially uniform illumination of selected parts of the room may be achieved.
A second embodiment in accordance with the present invention is substantially similar to the first embodiment, but may use more than one lightguide per wall, with light sources positioned as to satisfactorily illuminate the lightguides.
In a third embodiment in accordance with the invention, illustrated in
A fourth embodiment in accordance with the present invention describes a combination of the previous embodiments, with light guide light sources located both on the cornice 60 and the ceiling 80 for optimum room illumination. This embodiment is illustrated in
In a fifth embodiment in accordance with the present invention, illustrated in
The light source may include, but is not limited to, one or more LEDs coupled to a side-emitting optic. The optic material should be a transparent material such as glass or PMMA. An example optic geometry is shown in
Assuming that the optic axis 114 of the optic shown in
The reflecting and/or scattering surface from which the light reflects or scatters on reaching the walls may be bare wall or purpose designed reflector sheet 102. In the latter case, the reflector sheet may be designed to control the reflection direction by carefully directed metalized mirrored surfaces, or reflection through TIR in angled prisms. As in embodiment one, the angle at which light is designed to illuminate the room can be controlled by the angle of the reflecting surface, but may, for example, be chosen to be perpendicular to the length of the reflector strip.
This lighting arrangement of LED or other light source and optic may be retrofitted to an existing ceiling light fitting, thus minimizing or eliminating the need for expensive and disruptive installation of new lighting equipment.
A sixth embodiment in accordance with the invention describes an optic identical to that in the previous embodiment, shown in
A seventh embodiment in accordance with the invention is as per embodiment five except the exit surface of the optic is specifically designed to compensate for the fall-off in intensity, proportional to cost, which occurs when a point source emits light onto a planar surface such as a wall, as is illustrated in
An example of such an optic may be substantially the same as described in embodiment five, with a collimating surface 111 and TIRing surface 112, and an exemplary geometry is illustrated in
An eighth embodiment in accordance with the invention is as per embodiment five except in this case the optic is designed to provide selective illumination to illuminate specific areas of cornice. The same may be achieved through multiple optics and more than one light source. An example of an optic with a restricted angular range in the horizontal plane is shown in
A ninth embodiment in accordance with the invention is as per embodiment five, but describes illumination of a ceiling area rather than the cornice, as illustrated in
A tenth embodiment in accordance with the invention describes a variation of embodiment eight using a multipart optic, similar to that described in embodiment seven, to provide selective illumination to parts of the ceiling. An example of a possible geometry is shown in
An eleventh embodiment in accordance with the invention, illustrated in
In a twelfth embodiment in accordance with the invention, illustrated in
Although the invention has been shown and described with respect to a certain embodiment or embodiments, equivalent alterations and modifications may occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described elements (components, assemblies, devices, compositions, etc.), the terms (including a reference to a “means”) used to describe such elements are intended to correspond, unless otherwise indicated, to any element which performs the specified function of the described element (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein exemplary embodiment or embodiments of the invention. In addition, while a particular feature of the invention may have been described above with respect to only one or more of several embodiments, such feature may be combined with one or more other features of the other embodiments, as may be desired and advantageous for any given or particular application.
This invention could be utilized in both residential and commercial environments. The relative simplicity of the design requires minimal rewiring, and in some cases it might be possible to retrofit the sheet lighting straight into existing ceiling light fixtures.
The high level of user control will allow this lighting system to be used in a wide range of conditions, for example, general lighting, or subdued background lighting for presentations or watching display equipment such as televisions, without the risk of strong glare interrupting the viewing experience.
The ability to select only certain sections of the lighting system to illuminate will introduce opportunities for energy savings.
A further possibility exists to link the control of this lighting system to a central network and automate the system response o certain conditions or instructions.
