E-Ink is a company that makes high resolution displays, used by e-books and other handheld devices.
“LCD” is a generic term that covers an electronic display, which is activated by applying a voltage to a pixel element-a big display (such as a TV) will have millions of pixels.
Are the two pretty much the same? Or is an E-Ink display different?
BTW, many years ago I saw an experimental display (Kodak)-it was a thin sheet of flexible plastic-you could bend it. When will these be coming out?
Somebody will come back with a better answer, but my understanding is that one difference is that e-ink requires power to shift the pixels, but none to keep them there. LCD requires constant power. This is one reason the Kindle has a battery life measured in weeks, not days.
As well as being static, e-ink is reflective, relying on external light. LCD is transmissive, and requires a backlight. LED and OLED are light sources in their own right.
LCD is “Liquid Crystal” - based on the principle that a certain class of materials form elongated crystals that can arrange themselves regularly in their fluid if a charge is applied. When randomly oriented, the material is opaque; when regular, it is transparent and polarizes light. The crystals can be aligned regularly with a charge. Thus, a thin layer can pass (and polarize) light if a charge is present, or block it otherwise. Aligned in front of a light and between two polarized glass plates, it can allow or block light. (LCD are typically chemically a type of lipid, or fat.)
LED is Light Emitting Diode; as a current passes through a particular construction of semiconductor diode, it emits light.
E-Ink is usually formed by a collection of small speheres, that can be oriented based on a charge - for the e-Ink app, one side of the sphere is black, the other is white. sandwich these between two plates and where you apply a charge, you can flip from black to white.
The obvious advantage- LCD and LED need a continuous current to keep working. With e-Ink, once you set the ink a certain direction, it stays that way until changed - a lot less power. My Kindle can run for a month or more on one charge. Another advantage, of course - the eInk particles are simply reflecting (or not) the local light. They work the same in direct sunlight as in dark. Light sources like LED’s are only visible when not drowned out.
Most reflective LCD is very hard to read - think those awful grey calculators and watches; that is why LCD is typically back-lit, which gives it the same sunlight problem as LED.
The biggest advace recently in LCD TV is to replace the usual source - a flourescent backlight - with white LED’s now that white is cheap and easy to make. You can feel the difference in heat between an LED/LCD TV and the old LCD (flourescent) ones.
E-ink displays have very slow refresh rates (clearly, when you think that the pixels are a bunch of charged spheres moving around), but they are great for relatively static images, like books.
IMHO, the next big thing in LCDs will be grey-scale LCDs illuminates by field-sequential color LEDS.
It’s possible that OLEDs will displace LCDs before this happens, though.
AIUI the liquid crystal layer in an LCD is always transparent. It is sandwiched between crossed polarizers. Since polarizers only transmit light polarized in one orientation, each polarizer will each block the light the other one transmits so the sandwich is opaque. When activated by an electric charge the crystals align themselves and ‘twist’ the polarization of the light passing through, thus allowing it to pass through both polarizers.