From LCD to LED, the acronyms for display technologies can be boggling. Let's break it down in this article, and look at exactly how the different techs work.
AUTHOR: Louise Miller
I was born in Berlin, Germany. I studied in London and wrote my thesis on social media marketing. Now I works for a London-based PR company and I also loves blogging about technology and social media in My spare time.
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All displays are split in to two categories: Active Displays that work by emitting light, and Passive Displays that work with ambient light -the light that’s already around. A book is similar to a Passive Display; you can’t see what’s on the page unless you have light in the room. Almost all televisions are Active Displays; you could still watch them even if the room was completely in the dark.
Liquid Crystal Display (LCD). LCD displays are technically passive - they don’t shine any light on their own. However, most LCD display panels are paired with a backlight, which shines through the LCD display and makes it glow. The most basic example of an LCD display is a digital alarm clock (the old type, with chunky numbers):
The liquid crystals react to small changes in electric magnets (or electromagnets) either side of the display. These magnets create a field that the liquid crystals move around in. The field is programmed to make numbers appear on the display.
Of course, this alarm clock only has black liquid crystals against a plain background. Modern LCD displays such as those found on high-quality tablet PCs can show many different colours at the same time. They do this in several different ways.
1. Twisted nematic (TN) panels. These are the most common kinds of LCD display, and can be found on most laptops and in most ‘flat-panel’ LCD televisions. The liquid crystals are suspended in a matrix - kind of like how the chimes hang on a wind chime, but many times over, -, and react to small electric currents by ‘twisting’ around to various degrees. This ‘twisting’ causes different numbers of individually-coloured (usually Red, Green and Blue, or ‘RGB’) crystals to absorb different frequencies of light passing through them. Because TN panels are ‘backlit’ different colours are seen by the viewer. TN panels are very common, and are known to have fairly fast response times due to the short time it takes for the crystals to ‘twist’ around. Longer response times can cause ‘ghosting’ or residual images, to remain on the panel for short periods of time. TN panels are noted for poor colour reproduction, and a tendency to degrade in quality over time.
2. In-Plane Switching (IPS) panels. While TN panels make their liquid crystals twist perpendicular to the display panel, IPS panels make their crystals twist parallel to the panel. This necessitates higher power and leads to longer response times, but means that backlights don’t have to be so bright, as the panel behaviour is far more predictable. Because less light is absorbed (or ‘scattered’) by the panel itself, IPS panels produce more vibrant colour and can be viewed from a wider range of angles than regular TN displays. IPS is seeing use in a number of devices, from tablets to smartphones. Early versions of the technology required higher numbers of components in the display panel itself, which blocked more light, but this issue was resolved by LG in 2009.
Next up, we’ll look we’ll take a closer look at the backlight technology that turns passive LCDs in to active displays, and at other display technologies used on tablets, such as e-Ink. .
AUTHOR: Louise Miller
I was born in Berlin, Germany. I studied in London and wrote my thesis on social media marketing. Now I works for a London-based PR company and I also loves blogging about technology and social media in My spare time.
Medals Achieved:
Enthusiast
View All Authors
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