Illumination – Revolving
Patent
1992-04-08
1994-03-15
Husar, Stephen F.
Illumination
Revolving
362145, 359595, 359598, F21V 704
Patent
active
052950514
DESCRIPTION:
BRIEF SUMMARY
This invention relates to illuminating apparatus.
This invention has particular but not exclusive application to enhancing natural lighting within buildings, and for illustrative purposes reference will be made to such application. However, it is to be understood that this invention could be used in other applications, such as diffusers or concentrators for artificial lights, or as greenhouse panels.
Conventional windows permit incident light to pass into a building with its direction essentially unchanged. As the angle of incidence at which natural sun light falls on a window varies with time of day and the season, the light tends to fall in patches which move around the room, resulting in localised areas which are periodically overilluminated and deeper areas which must be illuminated artificially. The presentation of natural light in such an inconvenient form has led to the design of buildings in which most of the natural light is excluded by reflective windows, dark glass and blinds, with even illumination within the room being provided by power-consuming lights.
In has been recognized that it is desirable to redirect some of the incident sunlight through windows from its generally downwards path to an upward path, whereby the light may be reflected off the ceiling and/or high on a back wall to increase illumination deeper in the building. Attempts have been made to redirect incident light through a window by the substitution of reflectors within the window opening. However, reflectors proposed for use have suffered from the inherent disadvantage that the light so dealt with has emerged from the reflectors as a beam resulting in glare and other distractions not conducive to visual comfort. To date, such efforts have not met with commercial success as they have not been able to redirect and diffuse the light satisfactorily.
Other proposed means of achieving the desirable end of channelling incident sunlight and skylight include simple and complex light shelves, the complexities of the more efficient light shelves having specially structured surfaces making them uneconomic to manufacture. Additionally, prior art redirection apparatus suffers from considerable optical losses which tends to reduce the amount of light redirected, particularly when the light is skylight rather than the more intense direct sunlight. Consequently, prior art redirection apparatus has found only limited application, such as on the north side of buildings in the southern hemisphere.
A further major problem of prior art designs includes a failure to operate effectively over a wide range of angles of incidence of the incoming sunlight, resulting in the need for complex, expensive and inconvenient adjustment apparatus. Apparatus which is not adjustable or adjusted correctly results in the light being reflected in inappropriate directions, resulting in problems ranging from overillumination of the ceiling near the window wall of the building to transmission of unacceptable levels of glare.
The present invention aims to alleviate the above disadvantages and to provide illuminating apparatus which will be reliable and efficient in use. Other objects and advantages of this invention will hereinafter become apparent.
With the foregoing and other objects in view, this invention in one aspect resides broadly in illuminating apparatus for transmitting incident light and including:
a body member formed of a light-transmitting material;
an incident surface provided on said body member; and
a reflective surface associated with said body member so as to reflect refracted light whereby incident light may be refracted and reflected through said body member to emerge from said body member in a diffused pattern.
Preferably, the reflective surface comprises a pair of reflective surfaces of the body member, wherein the pair of reflective surfaces define a light guide within the body member such that light refracted through the incident surface is transmitted through the light guide and emerges from the light guide in a diffused pattern. Preferably, t
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patent: 4699467 (1987-10-01), Bartenbach et al.
Ruck N. "Beaming Daylight Into Deep Rooms" Building Research and Practice May-Jun. 1985, p. 144.
Ruck N. and Smith S. "Solar Beam Lighting using a Prismatic Panel" Proceedings of the Windows in Building Design and Maintenance Conference, Goteborg, Sweden, Jun. 1987.
Critten D. "Light Enhancement Using E-W Aligned Long Prismatic Arrays at High Latitude" Solar Energy, vol. 41, No. 6, 1988.
Whitehead L., Brown D and Nodwell R. "A New Device for Distributing Concentrated Sunlight in Building Interiors" Energy and Buildings 6 p. 119. 1984.
Howard T. et al. "Variable-area, Light Reflecting Assemblies" Proceedings of the International Daylighting Conference, Long Beach, Calif. Nov. 1986.
Husar Stephen F.
Queensland University of Technology
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