How does a liquid crystal display (LCD) work?

LCD stands for "Liquid Crystal Display." In today’s world, LCDs are ubiquitous – found in smartphones, computers, televisions, and everyday items like calculators and refrigerators.

But how exactly do LCDs work? In this blog post, we take a closer look at their basic functionality.

Liquid Crystals

Liquid crystals are the core of LCDs and give the technology its name. Unlike most other substances, which transition from a solid state with ordered molecules directly into a disordered liquid state when heated (e.g., snowflake → raindrop), liquid crystals maintain a certain degree of molecular order over a wide temperature range (e.g., -40°C to +90°C) when they reach the "liquid-crystalline" state.

How Is an LCD Structured?

A basic LCD cell works as follows:

Backlight:
Light from the backlight (usually LEDs) first hits the first of two polarization filters.

Polarization Filter 1:
You can think of a polarization filter as a grid. When unpolarized light hits the filter, only light aligned in one specific orientation or plane can pass through.

Glass Layers with Electrodes and Alignment Layers:
Between the two glass layers – which contain the electrodes and alignment layers – is a cavity filled with liquid crystal. On the alignment layers, the rod-shaped liquid crystal molecules align horizontally, forming a helical structure that rotates the orientation of the light by 90°. When a voltage is applied to the electrodes, the molecules realign vertically, and the light returns to its original orientation.

Polarization Filter 2:
Depending on the orientation of the light, it may or may not pass through the second polarizer.