Apple’s Retina Display: how does it work?

Features Richard Goodwin 16:45, 26 Mar 2012

We take a look at the science behind Apple’s Retina Display technology

Shifting three million tablet devices in three days is impressive – even by Apple’s standards. But that’s exactly what the Cupertino-based company has done with its third-generation iPad, which officially went on sale in the UK on March 16.

Critics argued that Apple hadn’t done enough with the design, giving special emphasis to the fact that the new iPad is actually 1mm thicker than its predecessor. Some compared it to the iPhone 4S, claiming that it, like the latest iPhone, was something of a damp squib. Yet despite all of this consumers and journalists alike do not seem disparaged by the new iPad.

In fact most reviews of the new iPad (including ours) have been positively glowing, even from staunchly anti-Apple columnists and writers. But why – what’s different this time around? One reason is undoubtedly the new iPad’s ultra-high resolution QXGA 4:3 aspect ratio Retina Display.

Displaying double the resolution of Apple’s iPad 2, the new iPad packs in 2048×1536 pixels across its 9.7-inch IPS panel at a density of 264ppi. That ppi count is quite a bit lower than the one for Apple’s iPhone 4S but that doesn’t matter because the iPad is viewed from a greater distance, typically 15-18-inches, which produces the same Retina Display effect.

Speaking to Gizmodo Australia, Dr Raymond Soneira of DisplayMate Technologies, said: ‘Apple’s definition of a “retina display” is actually for 20/20 vision (defined as one arc-minute visual acuity). 20/20 vision is just the legal definition of “normal vision”, which is at the lower end of true normal vision.’

He added: ‘There are in fact lots of people with much better than 20/20 vision, and for almost everyone visual acuity is actually limited by blurring due to imperfections of the lens in the eye. The best human vision is about 20/10 vision, twice as good as 20/20 Vision, and that is what corresponds to the true acuity of the Retina.’

‘So to be an actual “true retina display” a screen needs at least 573ppi at 12 inches viewing distance or 458 ppi at 15-inches – which the new iPad obviously isn’t. But there is still nothing else on the market that even comes close to what Apple has achieved with its new iPad, regardless of whether or not it’s a ‘true Retina Display.’

So what makes the Retina Display so good? That’s simple: pixels – and lots of them (3.1 million to be precise). Each pixel in a display is made up of a red, blue and green sub-pixel, which are responsible for creating the images you see on your iPad’s display by lighting up in sequence to produce colour.

But what makes the new iPad’s display so special is that Apple has crammed in four times as many pixels inside its Retina Display. Normally this would cause problems, as Apple pointed out when it launched the new iPad: ‘when you squeeze four times the pixels into the same space, signals can get crossed, colours become distorted and images get fuzzy.’

Apple solved this problem by adding vertical space between the pixels and signal. This technology is called Super High Aperture (SHA) and was originally developed by Sharp and JSR. SHA involves laying a 3-micrometre photo-definable acrylic resin layer on top of the display's thin-film transistors, says DisplaySearch.

This type of display technology, says the DisplaySearch, ‘reduces unwanted capacitive coupling and enables the electrode to be extended over the gate and data lines without causing cross talk or affecting image quality.’

Here’s a video explaining how the iPad Retina Display works:

As it stands Apple is way in front of the competition. But this won't last forever. We expect someone, most likely Samsung, to come along towards the end of the year with something that’ll beat Apple’s QXGA Retina Display.

Some of Microsoft’s up-coming Windows 8 tablets will also support resolutions similar to Apple’s iPad 3, but we won’t be seeing them until much later on in the year – Q4 most likely.

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