1. Safety
1.5 HD for fully enclosed projection systems
HD
Hazard Distance (HD) is the distance mea sured from the projection lens at which the intensity or the energy per surface
unit becomes lower than the applicable exposure limit on the cornea or on the skin. The light beam is considered (to
be) unsafe for exposure if the distance from a per son to the light source is less than the HD.
Restriction Zone (RZ) based on the HD
The projector is also suitable for re ar projection applications; projecting a beam onto a defuse coated projection screen. As displayed
in im age 1-3 two a reas should be c onsidered: the restricted enclosed projection area (RA) and the obser vation area (TH ).
RA TH
sw
PD
HDDIFFUSE
sw
RZ
sw
sw
PR
HD
REFLECTION
RESTRICTED
AREA
RESTRICTED
AREA
Image 1-3
RA Restricted Access location (enclosed projection area).
PR Projector.
TH Theater (observation area).
RZ Restriction Zone.
PD Projection Distance.
SW Separation Width. Must be minimum 1 meter.
For this type of setup 3 different HD shall be considered:
• HD as disc ussed in "High Brightness precautions: H azard Distance (HD)", page 6 , relevant for intrabeam exposure.
•HD
reflection
: the distance that has to b
e kept r estrictive related to the reflected light from the rear p rojection screen.
•HD
diffuse
: the relevant distance to be considered while observing the defuse surface of the rear projection screen.
As des cribed in "High Brightness precautions: Hazard Distance (HD)", page 6 , it is mandatory to create a r estricted z one within
the beam areas c loser than any NOHD. In the enclosed projection area the com bination of two restricted zones are relevant: The
restricted zone of the projected beam toward the screen; taking into ac count 1 meter Separation Width (SW) from the beam onward.
Combined with the restricted zon e related to the rear reflection from the s creen (HD
reflection
); also taking into account a 1 meter lateral
separation.
The HD
reflection
distance equals 25% of the difference between the determined HD distance and the p rojection distance to the rear
projection screen . To determine the HD distance for the used lens and projector m odel see graphs in chapter "HD in function of
modifying optics", page 9 .
HD
reflection
= 25% (HD – PD)
The light emitted from the screen within the observation shall never exceed the RG2 exposure limit, determined at 10 cm. T he
HD
diffuse
can be neglected if the m easur ed light at the sc reen surface is below 5000 c d/m² or 15000 LUX.
8
R5906714 DP2K CLP SERIES 09/05/2016
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