lamp shielding angle, ϕ

[] The angle between the plane of the baffles or louver grid and the plane most nearly horizontal that is tangent to both the lamps and the louver blades. (See Figure 27.)

Figure 27
Figure 27

(i) In Figure 27, the lamp shielding angle is formed by a sight line tangent to the lowest part of the brightness area to be shielded. H is the vertical distance from the brightness source to the bottom of the shielding element. D is the horizontal distance from the brightness source to the shielding element. Lamp shielding angle ϕ = tan-1 H/D.

(ii) The lamp shielding angle is frequently larger than the louver shielding angle, but never smaller.

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