Principle
Because Cholesteric Liquid Crystal is used, electronic paper has the characteristics like “thin, light, bright, and memory function”.
Cholesteric Liquid Crystal Material
Cholesteric Liquid Crystal only reflects light with certain wavelengths. When the light from sources such as the sun and light
bulbs enter the liquid crystal, it displays in full color by reflecting light with the specific wavelengths of red, green,
and blue.
Resultant color of red/green/blue mixture is determined by additive color mixture principle. When only red is reflected, it
will appear red. When red and green are reflected, it will appear yellow. When all colors are reflected, it will appear white.
When none are reflected, it will appear black.
How does the display work?
By applying electric power to transparent electrodes of each liquid crystal layer, liquid crystal molecules change directions, allowing the display to switch between reflect and not reflect.
・More in Detail
(1)- Liquid crystal molecules are formed in a spiral like structure. Normally, they are lined up vertically.
(2)- By applying low voltage to the portion that the light needs to pass through, spiral shaped molecules turn horizontal. The horizontal position will be stable even after the voltage is turned off.
(3)- To the portion that the light has to be reflected, higher voltage is applied, making the spiral shaped molecules stretch. When the voltage is turned off, the molecules kickback, making the spirals vertical and stable. (Returns to the state in (1) )
Merits of cholesteric liquid crystal’s characteristics
・Ultra low power consumption and image memory function
Since cholesteric liquid crystal is stable when the spiral axis is vertical or horizontal, direction of liquid crystal molecules can be maintained semi-permanently without power. This memory characteristic allows for power consumption only when rewriting, realizing the ultra low power consumption. Since no power is applied after an image is displayed, there is no flickering, making it easy for human eyes to see.
・Thin, Light, and Bright
Thin, light, and bright display is realized since components that are in conventional LCD (polarization plate, reflectors, color filters, and backlight) are not necessary.
