A waterproof MP3 player built for bright beach days is the first device with a color "e-paper" display, meaning it has no backlighting and thus can be read in direct sunlight. The display, from Qualcomm, consists of two layers of a reflective material. Some wavelengths of light bounce off the first layer; some pass through and bounce off the second. Interference between the two beams creates the color, and electrostatic forces control the distance between the layers.

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