On the stimulation and visibility by blinking light emitting block for low vision
Authors: Fujisawa Shoichiro , Okegawa Masaki , Sakami Kenji , Kawata Jyunji , Kaji Yoshio , Higuchi Mineo , Ito Shin-Ichi , Morimoto Jiro 
Published: June 2022

Approximately 80% of people with visual impairment have residual visual acuity. As such, the authors have developed a light-emitting block that is placed at the entrance of a pedestrian crossing to support those with visual impairment at night. A blinking light has generally been used for selectively distinguishing the target light source from the surrounding light source. However, this type of blinking (i.e., simple blinking) can be stimulating, making it suitable for night-time road construction sites but not for normal road environments. Therefore, the authors have focused on phase-in-phase-out blinking, which gradually brightens and darkens with each blink, thereby suppressing stimulation. This blinking pattern has been considered to reduce visibility just by suppressing the stimulus. However, focusing on the human sensory characteristics of adaptation and arousal, evidence has suggested the existence of a blinking cycle and pattern that awakens while suppressing stimuli.Therefore, the current study sought to identify blinking cycles and patterns that awaken while suppressing light stimulation. The intensity of light stimulation is evaluated via sensory evaluation. Based on the intensity of the stimulus and degree of arousal, we searched for the optimum blinking cycle that promotes adaptation, a human sensory characteristic, and arousal from the blinking pattern and verified the visibility of the obtained blinking pattern in individuals with visual impairment and healthy subjects. Previously, we had conducted an experiment in a region with a period of 4–7 s. This time, however, we conducted an experiment in a region with a period of 2– 3.5 s. This study verified that phase-in-phase-out blinking is effective for pedestrians while considering the surroundings.The purpose of this experiment was to determine the optimal blinking method for supporting people with visual impairment. Although it is desirable to provide support for people with visual impairment by promoting stronger visibility, introducing flashing blinks in public facilities may cause discomfort to healthy people around them. For instance, introducing a blinking light of approximately 1 Hz, which has a fast blinking cycle, at the entrance of a pedestrian crossing can enter the driver's field of vision, causing discomfort and making the driver look away, thereby leading to accidents. The ideal blinking light for support is that which limits arousal to some extent and does not induce discomfort. Based on the blinking patterns used in this experiment under the aforementioned condition, we believe that a fade-in-fade-out type pattern with a blinking cycle of 2 s and a lighting time of 2 and 3 s would be effective. The reason for this is that the intensity of the stimulus obtained from the sensory evaluation of healthy subject and those with visual impairment is suppressed, visibility is secured to some extent, and the blinking method does not induce discomfort. Thus, the fade-in-fade-out blinking method can be expected to suppress discomfort.