Phantom array effect from time modulated moving light sources

Chan-Su Lee^1*,2, ShinWon Park², Deok-Weon Song²

¹Department of Electronic Engineering, Yeungnam University; Gyeongsan, Rep. of Korea

²Department of Automotive Lighting Convergence Engineering, Yeungnam University; Gyeongsan, Rep. of Korea

*Contact email address: chansu@ynu.ac.kr

Abstract—This paper investigates phantom array effect from time modulated moving light sources without eye-movement. It is well-known that the phantom array can be detected when time modulated light sources are observed during saccadic eye movement. In the field test on the perception of automotive rear light using pulsed LED with different frequencies, peripheral observer, whose task was to fixate a target all the time, reported detection of phantom array effect (bead string artifact). To fixate a target means no saccadic eye-movement. We assumed that the phantom array effect without eye movement was caused by fast moving time modulated lighting source. Due to fast movement of light source with time modulation, observer may perceive time modulated light sources as separated multiple light sources. To simulate light source movement, we attached a time-modulated LED light source to a rotating disk. Different modulation frequency, rotating speed, and background illuminations are investigated. Modulation frequency to perceive phantom array effect depends on rotation speed as well as background luminance.

Keywords-phantom array; LED;time modulated lighting source; LED rear lamp