LG PB60G Service Manual page 92

Reference 1. Terminology
1. Light measurement unit
Classification MKS unit
Luminous flux lm (lumen)
Luminous intensity cd (candela) = lm/sr
Illuminance lx (lux) = lm/㎡
Luminance cd/㎡ = cd/sr·㎡
2. What is ANSI lumen? 2 What is ANSI lumen?
• PJTR brightness standard unit establishing by ANSI(American National Standards Institute)
• A standard which entire luminous flux of projected light can be measured regardless of a level of uniformity
in order to correct the measurements caused by different measurement locations.
→ Calculated luminous flux (unit lm) based upon the standard is called ANSI lm.
• Measurement procedure :
① Divide the projected screen into a nine equal size (Below figure)
② Measure a center illuminance at the 9 points and calculate the average (lx = lm / ㎡)
③ Calculate the projected screen size (㎡) ③ Calculate the projected screen size (㎡)
④ the calculated average from ② (lx = lm / ㎡) x projected screen size (㎡) = ANSI lm (lm)
* Projected screen size is not specified, but 40 inch projection is general.
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Only for training and service purposes
Meaning
The amount of emitted light that is measured based upon CIE standard luminous efficacy and the maximum luminous
efficacy
A value that a speed of light, directed in any directions from the light source, is divided by a solid
angle.
The amount of light entering per unit area (Light receiving part)
The amount of emitted light per unit area and per unit solid angle (Light emitting part) g p
Example) 40 inch (SIZE = 0.495 ㎡) when projecting, an average
lluminance 2,500 lx, .
▶ 2,500 ( lx ) x 0.495 (㎡)
p g ( g
= 1,237.5 (lm) *
∴ 1,237.5 ANSI lm 1,237.5 ANSI lm
g p )
LGE Internal Use Only