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Carbon nanotube backlight units (CNT-BLUs) offer advantages (including light weight and superior color performance) that cold cathode fluorescent lamp backlight units (CCFL-BLUs) cannot deliver. If these advantages find favor with liquid crystal display manufacturers, CNT-BLUs could possibly replace CCFL-BLUs. CNT-BLU light-emitting arrays are made by a thick-film screen printing process, which can leave dark obstructions within and between pixel areas. Thus, when the pixels light up, CNT-BLU arrays can display dark blotches within one or more pixels. Existing luminance uniformity measurements, such as Video Electronics Standards Association (VESA) or International Organization for Standardization (ISO) standards, are not designed to deal with this problem. These standards are based on the luminance of multiple non-adjacent points on a display; they cannot reflect the luminance change of adjacent pixels, which is important for measuring the uniformity of CNT-BLU. This situation is aggravated since CNT-BLU is still under development and the current luminance uniformity of CNT-BLU still cannot compete with that of CCFL. This study presents a new luminance uniformity measurement, line non-uniformity, for CNT-BLU. This method was compared with VESA and U Formula with respect to human perception. A set of CNT-BLU images with different levels of mottling was presented to 18 participants. The subjective acceptance thresholds for these images were then calculated. The uniformities using VESA, U Formula, and line non-uniformity approaches for these images were also calculated and fitted to the subjective acceptance threshold. The results showed that line non-uniformity was the best to fit the acceptance threshold; its R 2 ranged from 0.80 to 0.92 whereas the R 2 values of VESA and U Formula ranged from 0.00 to 0.49.

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Code-switching emerges as a valid strategy to communicate in writing. However, to type a multilingual document on a computer usually requires switching back and forth between different languages and input modes while using a keyboard. In many countries, bilingual keyboards are widely used. Their keytops display more than one set of labels. The present study used Chinese and English input texts to investigate the ''mental overhead'' incurred by code-switching and how colored keytop legends can increase typing performance for two types of typing tasks, namely, copy typing and generative typing. The results show that, when compared to keyboards with mono-colored keytop legends, colored ones not only reduced the ''mental overhead'' but also improved overall performance for both copy typing and generative typing tasks during code-switching, particularly for computer users with slow typing speeds. Although the issues discussed here are straightforward and the time differences are small, they affect millions of computer users who type in multiple languages every day.