Barco Balder - HD in Function of the Lens Throw Ratio (TR)

9. Risk Group 3 Safety
• H D as discussed in "High Brightness precautions: Hazard Distance (H D)", page 6 , relevant for intrabeam exposure.
• HDreflection : the distance that has to be kept restrictive related to the reflected light from the rear projection screen.
• HDdiffuse : the relevant distance to be considered while o bserving the defuse surface of the rear projection screen.
As desc ribed in "High Brightness precautions: H azard Distance (HD)", page 6 , it is mandatory to create a res tricted zone within
the beam areas c loser than any NOHD. In the enc losed projection area the combination of two restricted zones are relevant: The
restricted zone of the projected beam toward the s creen; taking into ac count 1 meter Separation W idth (SW) from the beam onward.
Combined with the restricted zone related to the rear reflec tion 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 a nd projector model see graphs in c hapter "HD in function of the
lens Throw Ratio (TR)", page 8 .
HDreflection = 2 5% (HD – PD)
The light emitted from the screen within the observation s hall never exceed the RG2 exposure limit, determined at 10 cm. The
HDdiffuse can be neglected if the m easured light at the screen surface is below 5000 cd/m² o r 15000 LUX.
9.5 HD in function of the lens Throw Ratio ( TR)
TR (Throw R a tio)
The ratio of the distance to the screen (throw) to the screen w idth.
HD versus Throw Ratio
0
0,2
0,4
0,6
0,8
1
1,2
1,4
1,6
1,8
0,5 0,9 1,3 1,7 2,0 2,3 2,7 3,1 3,5 3,9 4,3 4,7 5,1 5,5 5,9 6,3 6,7 7,1 7,5
Hazard Distance [m]
Throw Rao
Hazard Distance Thermal Acidental Exposure
Image 9-4
Hazard Distance in m eters versus Throw ratio of the lens for the Balder projector
Graphs shows Hazard Distance in
meters versus Throw ratio of the lens
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601–0442 BALDER 13/09/2017