Tech Help - Sign Face Brightness.

CALCULATION of SIGN FACE BRIGHTNESS Let:  L = Total length of tubing in a letter. B = Tube brightness in lumens per metre. A = Surface area of light emittering area (usually the front face of a letter). U = Utilisation factor for acrylic face (% transmitted) The light being generated in a letter in lumens given by the total length of tubing in metres multiplied by the brightness in lumens per metre. = B x L The light coming through the acrylic will be a fraction of that due to absorption = (B x L x U) / 100 The light emittered per unit area (lumens per square metre) = (B x L x U) / ( 100 x A)  lumens / metre2 and the candela per square metre (cd/m2) = [(B x L x U) / (100 x A)] x 0.318 candela / metre2 Example: for a letter of 0.90m2 area using 50% utilisation acrylic and 3m of 15mm HP20 running at 50mA. 15mm HP20 running at 50mA generates 763 lumens per metre. cd/m2 = [(763 x 3 x 50) / (100 x 0.90)] x 0.318             = 404 cd/m2 <<Return to top>>

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