Illumination – With static structure – Wall or ceiling
Reexamination Certificate
2001-11-13
2004-05-04
Cariaso, Alan (Department: 2875)
Illumination
With static structure
Wall or ceiling
C362S297000, C362S308000, C362S329000
Reexamination Certificate
active
06729741
ABSTRACT:
BACKGROUND TO THE INVENTION
The present invention relates to improvements in light fittings.
As the use of personal computers with visual display units (VDUs) has become more common, it is now desirable for office lighting to be provided which minimises glare on the VDU screen. Glare can occur from overhead lighting which emits light at an angle greater than 50° or 60° (all angles described herein are with reference to the vertical unless stated otherwise).
Light rays at this angle or greater bounce off VDU glass into the eyes of the user and can make reading the screen difficult (dependent on the intensity of the light).
To overcome the problem of screen glare the obvious solution is to utilise light shades which restrict light to less than a 60° beam. This light cut-off angle has an unfortunate side-effect that the upper walls and ceiling of the office become oppressively dark and uninviting.
To overcome the oppressive darkness created by light shades, “up-lighting” has been used to direct light upward from the light fitting to illuminate the ceiling.
However, in order for this technique to be successful the ceiling height of the office has to be about 3 metres high otherwise the effect of the up-lighting becomes a hot spot and creates annoying reflective glare. One will appreciate that not all office ceilings will be 3 metres high.
If the fitting is located close to the ceiling, patchy light spots result. Alternatively, if fittings are located too low then head room and room aesthetics may be affected.
Furthermore, any horizontal elements located on top of known “up-lighting” fittings can become dirty very quickly and cause premature performance and hardware degradation.
Another method of providing ceiling lighting involves using strip lighting within an “encove” adjacent the ceiling. To some degree the strip lighting creates a lightened effect across the ceiling however often only the corners appear bright and the remainder of the ceiling is still dark.
Furthermore, the gaps between adjoining strip lights can cause dark or unevenly lit patches on the visible portion of the ceiling. To remedy this, it is common to overlap the strip lights so no “gaps” are visible in the light projected onto the ceiling. It will be appreciated that this method is complicated to design and time consuming to install. Cost can also be a factor.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a light fitting for lighting of the ceiling that enables a uniform ‘wash’ of light for desirable aesthetic effect. Preferably the light fitting can be mounted close to a ceiling.
In a first broad aspect of the invention there is provided a light fitting for mounting adjacent to a ceiling adapted to receive a lighting device located within a housing, said housing being substantially sealed from the intrusion of dust, further including a substantially reflective surface to direct light in a desired direction across the ceiling and a diffuser mounted at a light emitting side of the housing, said diffuser being arranged at an angle close to vertical (wherein the ceiling is in a horizontal plane).
Preferably, the housing is adapted to receive elongate lighting devices, such as strip lights.
Preferably the invention, as described by the first broad aspect, may be utilised in a method of evenly lighting a ceiling, wherein a plurality of housings can be arranged end-to-end with diffuser edges substantially contacting.
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W. Elenbaas et al.,Fluorescent Lighting, edited by C. Zwikker, Philips Technical Library, 1952, pp. 152-154.
Cariaso Alan
Young & Thompson
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