Hd In Function Of The Lens Throw Ratio (Tr) - Barco Balder Series User Manual

Risk Group 3 Safety
• HDdiffuse : the relevant distance to be considered while observing the defuse surface of the rear projection
screen.
As described in "High Brightness precautions: Hazard Distance (HD)", page 6 , it is mandatory to create a
restricted zone within the beam areas closer than any NOHD. In the enclosed projection area the combination
of two restricted zones are relevant: The restricted zone of the projected beam toward the screen; taking into
account 1 meter Separation Width (SW) from the beam onward. Combined with the restricted zone related to
the rear reflection from the screen (HDreflection); also taking into account a 1 meter lateral separation.
The HDreflection distance equals 25% of the difference between the determined HD distance and the
projection distance to the rear projection screen. To determine the HD distance for the used lens and projector
model see graphs in chapter "HD in function of the lens Throw Ratio (TR)", page 8 .
HDreflection = 25% (HD – PD)
The light emitted from the screen within the observation shall never exceed the RG2 exposure limit,
determined at 10 cm. The HDdiffuse can be neglected if the measured light at the screen surface is below
5000 cd/m² or 15000 LUX.

6.5 HD in function of the lens Throw Ratio (TR)

TR (Throw Ratio)
The ratio of the distance to the screen (throw) to the screen width.
HD versus Throw Ratio
1,8
1,6
1,4
1,2
1
0,8
0,6
0,4
0,2
0
0,5 0,9 1,3
Image 6-4: Hazard Distance in meters versus Throw ratio of the lens for the Balder projector
Graphs shows Hazard Distance in meters versus Throw ratio of the lens
52 601–0443 /03 Balder
Hazard Distance Thermal Acidental Exposure
1,7 2,0 2,3 2,7 3,1 3,5
Throw Ra o
3,9 4,3 4,7 5,1 5,5 5,9 6,3 6,7 7,1 7,5