Philips Indoor Luminaires Indoor Furnishings User Manual


 
Lighting technique
Technical data
Philips indoor luminaires Technical data 12.49
Beam diagram
The beam diagram shows the characteristics of the light beam
produced by the luminaire/lamp combination for projectors,
downlights,reectorlampsandbre-opticterminations.Thediagram
gives the Visual Beam Angle (VBA), the beam spread angle (½I
max
) and
the sharpness of the contour as indicated by the K value, a measure
for the contrast of the light beam.
Additionally, the diagram gives the user information on the diameter of
the visual light patch, the diameter of the area of which the boundary
has a luminous intensity equal to 50% of the maximum illuminance,
and the diameter of the area of which the boundary has an illuminance
equal to 50% of the illuminance measured in the centre of the beam
(½E
0
). These diameters are presented for a range of vertical distances
below the luminaire.
The illuminance in the centre of the beam (E
0
) is available for the same
range of vertical distances below the luminaire.
Visual beam angle
TheVBAspeciestheangleatwhichthecontourofthebeamis
clearlyvisible.Incontrasttothebeamspreadangle,theVBAreects
what is perceived when a person looks at the visual light patch.
Beam width
The angle α at ½E
0
reectstheangleatwhichtheilluminancehas
dropped down to 50% of the maximum value measured in the beam
centre.
Beam spread
The beam-spread angle β at ½I
max
reectstheangleoverwhichthe
luminous intensity drops down to 50% of its peak value. The beam-
spreadangledoesnotreectthevisualappearanceofthevisuallight
patch.
Lighting of workstations with Display Screen Equipment
(DSE)
Glare and glare-reduction techniques are important aspects in interior
andespeciallyinofceandindustriallighting.Sincethe1970sthe
lighting industry and standardization institutes have developed various
methods to evaluate glare. Additional to this, the lighting industry has
developed advanced optical techniques to reduce the glare to the
required levels.
Acleardistinctionshouldbemadebetween:
- direct glare caused by luminaires and other sources of light, and
-reectedglarecausedbyacombinationofabrightlightsourceand
itsreectioninaglossysurface(seedrawing).
Standards in lighting have been developed to restrict both types of
glare.
With the introduction of computer screens, especially the early
models,therewerehighlyreectivedarkscreenswithbright
charactersthatgaverisetoproblemsinofceenvironments.
Subsequently,methodstoanalyzereectedglareincomputerscreens
have been developed for direct lighting.
α
½E
0
E
0
β
½E
0
E
0
Area 1 - Reected glare Area 2 – Direct glare
45° 85°
Viewing direction
Reected glare Direct glare
According to EN 12464-1 UGR according to EN 12464-1
Indoor_2008_Chapter_12_LIS.indb 49 20-05-2008 14:35:40