Glossary A–ZLetter E
E-paper
An e-paper display does not emit light but reflects ambient light like printed paper.
The image is formed by tiny coloured particles that are brought to the surface by electrical voltage.
The image stays without power; energy is only needed to change it. This makes e-paper suitable for displays that change rarely and should work without a power cable: shelf labels, door signs on meeting rooms or notice boards. It is easy to read in bright light, but in the dark it needs external lighting.
Changing the image takes longer than on a backlit screen; video and fast animation are not possible. Colour displays work with a small number of fixed colours, six being common. Clear areas and large type therefore work better than photos with soft gradients, which break up into dithered dots when converted. Operators should design content specifically for e-paper rather than simply reusing it from a large screen.