PDF《Indirect焖licker燩erception:?》

??2016?Rensselaer?Polytechnic?Institute.

?All?rights?reserved. Indirect?Flicker?Perception:? Stroboscopic?Effects?from?Light? Source?Flicker John?D.?Bullough,?Ph.D.,?FIES Lighting?Research?Center,?Rensselaer?Polytechnic?Institute ENERGY?STAR??Lighting?Webinar?Series February?25,?2016 ??2016?Rensselaer?Polytechnic?Institute.?All?rights?reserved. Outline ? Terminology?overview ? Metrics?for?detection?and?acceptability?of? stroboscopic?effects ? Comparison?of?metrics?and?specifications?for? characterizing?stroboscopic?effects ? Application?considerations Note:?Focus?is?on?visual?perception?issues

2 ??2016?Rensselaer?Polytechnic?Institute.?All?rights?reserved.

3 Terminology Frequency (cycles per second) flicker index: 0.5 flicker index: 0.9 flicker index: 0.5 flicker index: 0.17 ??2016?Rensselaer?Polytechnic?Institute.?All?rights?reserved.

4 Terminology Modulation depth (Percent flicker: [max-min]/[max+min]) flicker index: 0.5 flicker index: 0.9 flicker index: 0.5 flicker index: 0.17 ??2016?Rensselaer?Polytechnic?Institute.?All?rights?reserved.

5 Terminology Modulation depth (Flicker index: area above average/total area flicker index: 0.5 flicker index: 0.9 flicker index: 0.5 flicker index: 0.17 ??2016?Rensselaer?Polytechnic?Institute.?All?rights?reserved.

6 Terminology Duty cycle (% of time light output > 10% of max) flicker index: 0.5 flicker index: 0.9 flicker index: 0.5 flicker index: 0.17 ??2016?Rensselaer?Polytechnic?Institute.?All?rights?reserved.

7 Terminology Waveform shape (rectangular vs. sinusoidal) flicker index: 0.5 flicker index: 0.41 ??2016?Rensselaer?Polytechnic?Institute.?All?rights?reserved. Detection?and?Acceptability?of? Stroboscopic?Effects

8 Frequency?→ Percent? flicker?(flicker? index)?↓ 100? Hz 300? Hz 1000? Hz 3000? Hz 10000? Hz 100% (0.5) 54% (0.27) 25% (0.13) 5%? (0.03) 100% flicker 0% 20% 40% 60% 80% 100%

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6 rel. time rel. light output 54% flicker 0% 20% 40% 60% 80% 100%

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6 rel. time rel. light output 25% flicker 0% 20% 40% 60% 80% 100%

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6 rel. time rel. light output 5% flicker 0% 20% 40% 60% 80% 100%

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6 rel. time rel. light output Experimental?Task:?Waving?a?light\colored?rod?against?a?dark?background (0.5 flicker index) (0.27 flicker index) (0.13 flicker index) (0.03 flicker index) ??2016?Rensselaer?Polytechnic?Institute.?All?rights?reserved.

9 Results:?Detection

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10000 5% 25% 54% 100% Flicker Frequency (Hz) Percent Flicker (%) Detection of Stroboscopic Effects 80%-100% 60%-80% 40%-60% 20%-40% 0%-20% 0.5 0.27 0.13 0.03 Flicker Index d = [(25p + 140)/(f + 25p + 140)] * 100% (d=%detection, f=frequency in Hz, p=percent flicker=flicker index * 200) ??2016?Rensselaer?Polytechnic?Institute.?All?rights?reserved.

10 Results:?Acceptability a =

2 C 4/[1 + f/(130 log p C 73)] (a=rating value, f=frequency in Hz, p=percent flicker=flicker index * 200) ??2016?Rensselaer?Polytechnic?Institute.?All?rights?reserved. Visual?Performance?Study

11 ? Predictions?of?detection?and? acceptability?under?three?flickering? lighting?conditions: ? 100?Hz/0.5?flicker?index?(100%?flicker):? 96%?detection,?\0.6?acceptability ? 100?Hz/0.13?flicker?index?(25%?flicker):? 88%?detection,?\0.1?acceptability ? 1000?Hz/0.5?flicker?index?(100%?flicker): 73%?detection,?+1.4?acceptability ? Participants?performed?a?low\contrast?numerical?verification?task ? Predicted?detection?and?acceptability?was?correlated?with?the? number?and?rate?of?errors?for?this?visual?task (Bullough,?Skinner?and?Sweater?Hickcox 2013) ??2016?Rensselaer?Polytechnic?Institute.?All?rights?reserved. Which?Flicker?Metrics?are? Most?Useful? ? ASSIST?(2012)?detection?and?acceptability?models ? Correspond?to?the?specific?visual?task?conditions?used? in?the?underlying?experimental?data ? Rapidly?waving?a?light\colored?rod?against?a?black? background ? Percent?flicker ? Used?by?IEEE?Standard?1789?and?California?Title?24? requirements ? Does?not?incorporate?flicker?frequency