LED lighting Alan Yu
Alan Yu
AE
ayu@intersil
Shenzhen, PR of China
April 4, 2007
Photometry‐How is Light Measured
八年级语文教学总结and Quantified?•Luminous Intensity (I)发光强度‐candela Luminous  光通量lumen
•Flux(Φ)‐
•Illuminance(E)照度‐lux
•Luminance (L)辉度‐nit
Luminous I ntensity(发光强度)•describes the intensity of light in a particular direction. SI base  is candela(symbol: cd)
会计学就业方向
unit
三年级上册数学期中考试试卷分析>蚕豆怎么做好吃•The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of
frequency 540 x 1012Hz and that has a radiant intensity in that direction of 1/683watt per steradian.
•The  official unit of illumination, the candlepower, former illumination candlepower was defined as the light given off by a candle of pure
spermaceti burning at a rate of 7.776 grams (120 grains) per hour.李柄熹多大
•A common candle emits roughly 1 cd.
l h b lb
•A 100 W incandescent light bulb emits
about 120 cd.
Luminous Flux光通量(Φ)•total amount of light energy given off by a source.
SI unit  is lumen(lm) 流明.
•1 lm = Flux of light produced by a light source that emits 1 cd of  intensity over
luminous a solid angle of one steradian.
•the flame of a candle generates about  lumens. th fl f dl t b t12l
•A 60 watt incandescent lamp, such as the type you would find in your home, is rated at 890 lumens.
张馨予出轨霍建华Illuminance (E) 照度
()•Measure  the  amount  of  light  which  falls  on  a  surface. SI  (lx)=lm/m 2unit  is  Lex (lx), . •E= Φ / A
where  Φ:  lumens  striking  a  surface  A:  the  area  of  the  surface.
•values  can  be  determined  for  surfaces like both  horizontal  surfaces,  a  desktop, and  vertical  surfaces, like  a  chalkboard.footcandle
•
夏日阳光下为100,000Lx •Metercandle=lx; footcandle •
阴天室外为10000Lx ；•
室内日光灯为100Lx ；•
距60W 台灯60cm 桌面为300Lx ；•
电视台演播室为1000Lx ；•
黄昏室内为10Lx ；01L •
夜间路灯为0.1Lx ；•烛光(20cm 远处)10～15Lx 。