Liquid-crystal display has become one of the leading display technologies used in the production of TVs, computer monitors, smartphones, tablets, portable video game consoles and other display devices. It receives its namesake from its use of liquid crystals, which are responsible for propagating light and, therefore, creating images. But unless you’re familiar with their design, you might be wondering how exactly LCDs are able to produce images.
Liquid Crystals Are Embedded Between Two Glass Layers
While there are different ways to design an LCD, most feature a similar design in which liquid crystals are embedded between two glass layers. There’s a top glass layer as well as a bottom or rear glass layer. Between these two layers is a container filled with micro-sized crystals suspended in a fluid solution. The top and bottom glass layers essentially sandwich the liquid crystals in place.
All LCDs also have polarizing film placed on both the top glass layer as well as the bottom glass layer. The presence of these polarizing films allows LCDs to selectively pass light, thus creating images. The polarizing film on the top glass layer is aligned in an opposite manner to that of the bottom glass layer’s polarizing film. But as the light reaches the bottom film, the two films become aligned so that light can pass through.
Backlighting to Illuminate the Liquid Crystals
All LCDs require the use of a backlight to illuminate the liquid crystals. Some people assume that LCD technology, in itself, is capable of producing illumination, but this isn’t necessarily true. Light-emitting diodes (LED) can produce their own illumination, but LCDs require a separate source of illumination via backlighting.
In the past, cold cathode fluorescent lamp (CCFL) was the most common backlighting solution used in LCDs. While some LCDs still use this backlighting technology, most manufacturing companies have since switched to LEDs. LED backlighting lasts longer, consumes less energy and produces less heat.
There are actually several types of LED backlighting used in LCDs. WLED backlighting, for example, is characterized by a grid-like array of white LEDs embedded behind a diffuser. This relatively new LED backlighting solution has become popular because it’s able to dim dark areas of the LCD without affecting the other pixels. In addition to WLED, another common type of LED backlighting used in LCDs is RGB-LED. With RGB-LED, the LCD is illuminated with a complete grid-like array of “red, green and blue” LEDs rather than white LEDs. Therefore, RGB-LEDs are able to provide a much wider color gamut.