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Measuring the Readability of Electronic Devices:

論文題目
氏

名A Study of the Effects of Illuminance, Font Sizes, and Visual Acuity（電子情報機器の可読性の測定：照度、文字サイズ、視力の影響に関する研究）

LEGE Ranson Paul論 文 内 容 の 要 旨
At present, the commercial development of visual display terminals (VDTs) ismoving at a rapid pace. The market is replete with many gadgets made for all ages.
These devices require both visual and tactical manipulation and can affect a person in avariety of ways. Consumers of such products should not only be wary of price andquality but the safety of such devices. In this respect, safety refers to visual fatigue
which is related to the performance of the reading device. While the International
Organization for Standardization attempts to keep pace with the market changes, manyof today’s advances are moving ahead of the recommended standards for usage of suchproducts. Thus, this dissertation focuses on the effects of illuminance, font size andvisual acuity on the ability of people of all ages to read from such devices.
The field of ergonomics is concerned with understanding how humans interact
with other systems (particularly mechanical) and as such has done much work in areas
related to the impact of computer technology on the physical well-being of humans.
Influences such as environmental lighting, contrast ratios, visual distance, font typeand sizes as well as the condition of the individual eye are all of concern whenstudying the interaction between human beings and such technology. As such, thisdissertation focuses on the effects of environmental illuminance, font sizes and visualacuity because they cover an environmental factor (lighting), a mechanical element(fonts) and elements of the human condition (aging and lens cataract cloudiness).
The study encompasses a look at some of the main VDTs available on themarket today including the backlit type Liquid Crystal Display (LCD), e-ink with thefront light type (Electronic Paper Display with an Integrated Light Unit), and thestandard E-ink or E-reader (Electronic Paper Display without front light). Much of theliterature has focused on the readability of LCDs and so the primary interest in thisstudy is a comparison of these two different types display terminals.

学位関係This dissertation represents the combination of three different experiments thatstudied the readability of various electronic devices under different aspects of environmental
conditions and visual performance. All three experiments included the participation of 95 ormore subjects in measuring and evaluating the ease or difficulty of reading in English fromvarious devices under different conditions. The main reason for using English was becauseof an interest in the development of globalized standardization with regard to the usage ofelectronic devices. Conventional paper text was used as a comparative reference because
manufacturers of such products often claim that their innovations are close to paper.
In the first experiment, 110 participants took part in a study that evaluated theperformance of an LCD, an Electronic Paper Display (EPD), and an EPD with an Integrated
Light Unit (ILU-EPD) under 14 different levels illuminance. The experiment included bothobjective and subjective measures. First, the participants read aloud from a text block foreach level illuminance, and the experimental team collected the correct number ofresponses. This procedure was done for each device including the paper text. Second, after
reading from text block of words, the readers evaluated the readability of each device using
a Visual Analysis Scale (VAS). The results indicated that all the devices were equally
readable between 200-500 lx; however, the readers rated the LCD and ILU-EPD as easier toread at less than 200 lx compared to paper and the EPD with no additional lighting system.
The second experiment looked at the readability of the Courier font type and sizes
on different visual display terminals. Courier is a monospaced font type that allows for easeof objective measurement in terms of evaluating the visual performance of electronicdevices. In this test, 99 readers grouped according to age looked at and evaluated 8, 12, and16 point sizes on an LCD and electronic device, with paper text as a reference. A two-way
ANOVA was used to check for significance. The results from this experiment found thatindividuals under 65 years of age could read at the 8 point size while those over 65 years ofage found it difficult.
The third experiment measured the effects of aging, visual acuity, and lens cataract
cloudiness on the legibility of two fonts displayed on an e-paper device. The study
compared the legibility of a serif font (Times New Roman) and sans serif type (Helvetica)
as discrepancy exists in the literature as to which font type is best for screen terminals. The
study included 133 participants who were measured according to their binocular near visualacuity for 50 cm. The results from this experiment indicated that the legibility of e-paper
displays is influenced by age, cataract cloudiness, and 50 cm visual acuity.
The results of the above three evaluation experiments reported in this paper give
useful knowledge on the readability of characters of various types of e-book terminals inorder to standardize for the safety of users, and it contributes to the international
standardization.

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