An Experimental Study on Evaluating Glare in Blue

Light Exposure

Daisuke Miyazaki, Kimi Ueda, Soma Kawamoto, Wakako Takekawa, Hirotake Ishii, Hiroshi Shimoda

Graduate School of Energy Science, Kyoto University, Japan

2019/7/26 1

Introduction

• How to improve work performance in an office• by controlling indoor environment

• Exposure to blue light improves human arousal

2

Control indoor

environment

Improve arousal

Improve work

performance

temperature, air flow, lighting

Experiment Result ConclusionIntroduction

Blue Light

• Photoreceptors in the retina called melanopsin cells*• improve human arousal when stimulated

• have spectral sensitivity peaks around the wavelength of 480nm

3

Experiment Result Conclusion

retina

Melanopsin cells

Blue Light Improve arousal

Improve work

performance

*Provencio, I., Jiang, G., Grip, W., Hayes, W., Rollag, D.: Melanopsin: An opsin in melanophores, brain and eye. In: PNAS, Vol. 95, No. 1, pp. 340-345 (1998)

Introduction

Previous Study*

• An experiment was conducted• to evaluate the intellectual concentration improvement

effect by blue light exposure

• As the result,• the feeling of dazzling disturbs intellectual work

4

Experiment Result Conclusion

Blue light exposure

Cause the feeling of dazzling

disturb intellectual

work

*Miyazaki, D., Ueda, K., Kawamoto, S., Takekawa, W., Ishii, H., Shimoda, H., Yabuki, J., Uchida, T., Noguchi, H.: An Experimental Study on Intelligent Concentration Improvement by Blue Light Exposure. In: Proc., Human Interface Symposium 2018 (2018) (In Japanese)

Introduction

Purpose of this Study

• to find which blue light conditions cause feeling of dazzling or disturb intellectual work

• four blue light conditions (shown in next slide)• changing Luminance and Light emitting area

5

Experiment Result Conclusion

Experience Blue Light Conditions

Answer questionnaire

about glare

Evaluate the degree of

glare

Experiment

Introduction

Light Conditions in the Experiment

6

Introduction Result Conclusion

(a) 1 unit 100% luminance output (b) 2 units 50% luminance output

(c) 4 units 25% luminance output (d) 8 units 12.5% luminance output

• Total amount of blue light is the same in all conditions

Experiment

Cognitive Task

7

Introduction Experiment Result Conclusion

UNDO

Meaning category

same differentcorrectwrong

Ineq

ual

ity

ID : 01Finish

PEACH : SOCKS

6742 < 6675

• Comparison Task

Procedure of Experiment

• 25 university students• males from 19 to 26 ages with normal eye sight

8

Introduction Result Conclusion

AnswerPhysical Condition questionnaire and Glare questionnaire

Practice

5

Rest

10

Explanation

15

Rest

10

SET1

5

SET2

5

Rest

10

SET3

5

Rest

10

SET4

5

Total : 90min.

Finalquestion

naire

10

(min.)

Experiment

Questionnaire

• Physical Condition questionnaire• subjective fatigue, arousal, concentration with 100 grades

• Glare questionnaire• subjective dazzling of each light condition with 9 grades

(shown in next slide)

• Final questionnaire (choice and free description)• which conditions were distractive

• which conditions were not acceptable

9

Introduction Result ConclusionExperiment

Glare Questionnaire*

10

Introduction Result Conclusion

*BGI(British Daylight Glare Index): Technical Report No. 10, IES-London, 1967.

• Circle one number to answer

Imperceptive

Perceptible but not unacceptable

Unacceptable but not uncomfortable

Uncomfortable but not intolerable

Intolerable9

8

7

6

5

4

3

2

1

Experiment

Result of Glare Questionnaire

11

Introduction Experiment Conclusion

1

2

3

4

5

6

7

8

9

1台 2台 4台 8台

blue light conditions

1 unit 2 units 4 units 8 units

5.6 1.6

4.2 1.84.8 1.5 4.8 2.0

(a) 1 unit (b) 2 units

(c) 4 units (d) 8 units

Dazzling

Result

Intolerable

1 unit 2 units 4 units 8 units

the number of answers 11 3 6 8

Result of Final Questionnaire

12

Introduction Experiment Conclusion

Distractive

1 unit 2 units 4 units 8 units

the number of answers 17 10 8 8

because light emitting area was large

because intense light was exposed

asymmetrically asymmetry

Result

Conclusion

• Measured the subjective evaluation of glare

• As the result, 3 factors cause feeling of dazzling• Luminance

• Asymmetric irradiation

• Light emitting area

• In the four light conditions,• 2 units condition is the best in the point of glare

13

Introduction Experiment Result Conclusion