What is LCD?

1.1 History of LCD Display Development

1. History of LCD
2. Discovery stage

In 1888, it was discovered by Austrian botanist F. Reinitzer.

In 1889, it was named “liquid crystal” by German physicist Otto Lehmann.

1. Development stage

In 1963, RCA of the United States proposed to apply LCD to display. In 1969, synthetic room temperature liquid crystal (MBBA) was developed.

1. Application stage

In 1973, clocks and desktop computers appeared.

In 1979, game consoles and 1-6mm card motors appeared. In 1982, detectors appeared.

In 1984, it was applied to 2-inch TFT color LCD TVs. In 1986, it was applied to STN typing computers.

In 1988, it was applied to 3-14-inch TFT color LCD TVs.

In 1989, it was applied to 100-inch color LCD TVs and laptops. In 1990, it was applied to 10-inch color LCD notebook computers.

In 1994, 21-inch TFT was put into trial production (Sharp). 14-inch color STN LCD was put into trial production. Now: LCD display technology has achieved unprecedented development and wide application.

A. Liquid crystal states

Liquid crystal is a substance between liquid and solid, which changes between liquid and solid phases with temperature changes. Its main structure is a structure with a benzene ring in the middle and -CN and -F connected at both ends.

B. Molecular structure of liquid crystal

C. Types of liquid crystals

There are three states of liquid crystals. Currently, LCDs mainly use liquid crystals in the nematic state.

Nematic phase liquid crystal: The center of gravity of the nematic molecule is disordered, making it flow like ordinary liquid, but the director of the molecular rod is roughly consistent.

Smectic phase liquid crystal: The molecules form a layer-by-layer structure, and the thickness of the molecular layer is about the length of a molecule; the molecules are arranged perpendicular to the plane of the molecular layer, and the center of gravity of the molecules is disordered in the molecular layer, forming layers of two-dimensional fluid.

Cholesteric phase liquid crystal: The center of gravity of the Cholesteric molecule is disordered, but the director of the molecule roughly points to one direction in a plane. In the direction perpendicular to this plane, the director of the molecule will rotate to form a helical structure.

1.2 Display classification and characteristics

1. Classification by self-luminescence and receiving external light sources

Light-receiving displays: LCD (Liquid Crystal Display), LED (Electro Chemical Display)

Light-emitting displays: CRT (Cathode Ray Tube), VFD (Vacuum Fluorescent Display), LED (Light Emitting Diode), PDP (Plasma Display Panel), ELD (Electro Lumineescent Display)

2. Classification by drive mode

Active Matrix:2-terminal type (Metal/Insulator/Metal, MIM),3-terminal type TFT (CdSe, a-Si, p-Si)

Static/Simple Matrix:TN（Twist Nematic）,SBE（Super-twisted Birefringence Effect）,ECB（Electrically Controlled Birefringence）,FLC（Ferroelectric Liquid Crystal）,STN（DSTN，FSTN）

3. Features of various display screens

1.3 Features of LCD display

Low voltage drive

Low current consumption

Small size, light weight, and increasingly thin

Can be used in any size

Mature technology, low cost

Large viewing angle, can display at full viewing angle

Use is subject to temperature restrictions

Requires external backlight

6.86 inch Bar TFT Display 480*1280 pixels 1100 nits High Brightness TFT Screen