Effects of Glass Transmittance, Font Brightness and Font Size on Text Legibility in LCD Home Appliance Interface

This study experimentally investigated the impacts of major design variables of a liquid crystal display (LCD) home appliance control interface on interface text legibility. The home appliance of interest was a washing machine. The experimental setup simulated a real-world washing machine usage condition challenging in terms of visual information processing. Independent variables were surface glass transmittance (25%, 50%, and 75%), font brightness (60%, 75%, and 100% at 25, 44, and 90 cd/m²), and font height (3, 5, and 7 mm). Response time (RT) and proportion of errors (PE) were employed as the dependent measures. Regression analysis was conducted to analyze data. The results showed that: (a) an increase in the font height resulted in decreases in RT and PE, and (b) increasing glass transmittance and font brightness reduced RT and PE for the 3 and 5 mm font heights. The study findings would inform the design of home appliance control interfaces.