Philips Indoor Luminaires Indoor Furnishings User Manual


  Open as PDF
of 78
 
Lighting technique
Philips indoor luminairesTechnical data12.50
Note:
For certain special places, for example where sensitive screens or variable
inclination are used, these illuminance limits should be applied for lower luminaire
elevation angles (e.g. 55°).
Direct lighting uses luminaires designed to emit most of their light
output directly onto the working plane. Luminaires for direct lighting
can be surface-mounted, recessed into the ceiling or suspended. They
are generally visible as individual bright elements in the space, and can
appearasadistinctanddistractingobjectwhenreectedonadisplay
screen. In cases where the screen displays bright characters (words
and numbers, etc.) on a dark background, as was originally the case
withtherst-generationVDUs,thereectedimageisseenagainst
thisdarkbackground.However,iftheinformationisdisplayedindark
characters on a light background, as in most modern screens and
softwareprograms,thereectionswillbelessconspicuous.Toavoid
glareproblemsCENhasestablishedluminancelimitsforluminaires
and for typical screen qualities. These are shown in Table 1.
Screen classes in accordance
with ISO 9241-7
I II III
Screen quality Good Medium Poor
Average luminaire luminances
reflected in the screen
≤1000cd/m
2
≤200cd/m
2
Table 1. Screen classes in accordance with ISO 9241-7
Note:
a) The appropriate luminance limit for luminaires (according to European standard
EN 12464-1) can be selected when the nature of the screens and software to be
used is known. If this information is not known or is not denite, the lower limit of
200 cd/m
2
should be selected.
b) The DSE and, in some circumstances the keyboard, may suffer from reections
that cause disability and/or discomfort glare. It is therefore necessary to select,
locate and arrange the luminaires to avoid high-brightness reections. The
lighting designer should determine the mounting zone that is causing disturbance,
then choose equipment and plan mounting positions which will not cause any
disturbing reections.
Luminaire luminance limits with downward ux
Table 1 gives the limits of the average luminance of a luminaire at
elevation angles of 65° and above from the perpendicular, radially
around the luminaires, for workplaces with display screens. The displays
are usually positioned vertically or inclined up to a 15° tilt angle.
L ≤ 1000 cd/m
2
or ≤ 200 cd/m
2
all around the luminaire
65°
Indoor_2008_Chapter_12_LIS.indb 50 20-05-2008 14:35:41
 previous next