The WAM-5500 (Shigiya Seiki Co., Japan) which can measure accommodation at 7 Hz continuously, was used as part of the device. The EMR-9 (NAC Imaging Technology, Japan) was used to measure convergence.An automatic motorized X-axis linear stage KXL06200-N2-FA (Suruga Seiki Co., Japan) was used for the target presentation.convergence and accommodation were analyzed when subjects gazed at a visual target displayed on paper, LCD, an E-ink device, and Organic EL (PSVita, Sony Corp., Tokyo) moving in the depth direction. As the text size and font of the target were changed, a comparison was made of the amount of change observed in accommodation with that observed in convergence.
A typical example of a measurement result in the case of the organic EL is shown in the lower left and the lower right figures. The lower right figure shows the measurement result for accommodation, with the vertical axis showing the diopter value and the horizontal axis showing time. The position of the target was computed based on the drive and stop timing of the rail, and the distance of the target is converted into diopters. It turned out that convergence and accommodation followed and reacted to the motion of the target.

Analysis of the dependence of accommodation and convergence on the display method when a target moves in the depth direction

本文へジャンプ Feb. 2.2016 
 With the spread of electronic books and compact tablets, the available display styles vary greatly compared with the medium of paper. Small tablets and digital books are used widely and in all kinds of situations, especially during passenger commutes on the bus or train. We have paid attention to the focusing characteristics of the crystalline lens. At the same time, we examined convergence which is important movement to perceive depth as well as accommodation. We developed an experimental device that measures the lens accommodation and convergence eye movement simultaneously and can be combined with equipment that moves a small tablet or a digital book linearly in the depth direction. In previous experiments [1], we compared accommodation and convergence in association with changing the font, font size and display medium. The results suggested that accommodation is font dependent. In contrast, no typical tendency was found for convergence. In the present study [2], we experimented by newly adding organic EL as a display medium. We also investigated whether accommodation and convergence showed any dependence on the display medium. From the measurement results for organic EL, focusing tended to almost match the visual target in the case of distant vision and convergence tended to match with a location slightly more distant than the visual target.  In the case of near vision, although convergence had a tendency to almost match the visual target, accommodation showed great variation among subjects, and no consistent trend was observed. In the case of other media, since the results for near vision and distant vision showed large variation and the results varied greatly between subjects, no typical tendency was found. In the comparison among the media, a tendency was observed for the accommodation error to be small when the organic EL was used.
References 1)Y. Yokoyama et al., Analysis of change of accommodation and convergence dependence on the display methods when a target moves along the depth direction, IMQA2014
2)Y. Yokoyama et al., Analysis of the dependence of accommodation and convergence on the display method when a target moves in the depth direction,IDW2014

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