LG has just unveiled its G4 smartphone and with it a new IPS Quantum Display.

Apart from being Quad HD in resolution - delivering 2,560 x 1,440 pixels, 538ppi - it is brighter with a higher contrast ratio and wider colour gamut than the earlier LG G3's QHD LCD display.

But what actually is an IPS Quantum Display and how does it work?

A quantum leap

The 5.5-inch IPS display on the G4 has some pretty impressive number claims including 20 per cent greater colour reproduction, 25 per cent brightness improvement and 50 per cent greater contrast than the G3 - all without chewing through more battery life, the company claims.

But it's the wider colour range that's the really interesting part.

Colour standards

The G4 screen has been created to close-in on the standards used by Hollywood movie studios, dubbed DCI or Digital Cinema Initiatives. And while no display device can present the full spectrum of visible colour, the DCI colour gamut is a wide array of visible colours that can recreate a rich overall image.

The G4's quantum display, LG says, offers 98 per cent of the DCI colour gamut - with deeper saturation in the reds and blues, some green saturation lost, hence the 98 per cent quota.

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Before DCI formed in 2002 the sRGB gamut was prevalent from 1996 - a standard that most screens still aim for. The main difference with DCI is that it includes a wider range of reds than sRGB, which is the colour that the human eye can see more variation in.

The G4's Quantum Display produces more accurate colours, especially these reds, and a wider range of colours than other LCD screens. But how?

How was LCD physically improved?

One of the technologies used in the IPS Quantum Display is Advanced In-Cell Touch - a first for Quad HD, says LG. By combining the LCD and touch sensor into a single layer LG has been able to offer better colour reproduction as well as touch-sensitivity. 

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Display brightness has increased by 25 per cent in the G4 over the G3. This is achieved by employing what LG calls N-Type Liquid Crystal.

Now for the science. Traditional LCD screens let light through or block it by bending it using polarised liquid crystals, achieved by using an electric field created by electrodes in the vertical ends. LG has shifted this to the horizontal ends in the G4 so each crystal can be more accurately controlled - resulting in a more uniform layer which allows more light through. This means that the handset can support a brighter display without using any more power, since there is less light being blocked and wasted.

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Above: LG G3 (left) and LG G4 (right) both set to 100 per cent brightness (Auto switched off)

Contrast is the other area that the Quantum Display manages to improve, apparently by 50 per cent over conventional LCD screens. That means deeper blacks, sharper text and improved contrast ratio - which is defined as the difference between possible black and white levels. This has been achieved by using a UV light photochemical treatment that achieves a 1500:1 contrast ratio, whereas normal LCD offers a 1000:1 ratio.

How is Quantum Display different from Quantum Dot? 

Quantum Dot technology, found in some TVs, requires a film or tube layer which would mean a big bezel in phones. As such Quantum Dot screens have not been used on smartphones since it would not only mean a larger bezel but also a thicker panel.

Quantum Dot uses blue LEDs while the Quantum Display uses both blue and white LEDs. Quantum Display uses potassium and nitrogen based compounds in combination with the blue LED to achieve red and green colours where Quantum Dot uses that tube or film layer.

Both display types are based on the transition of energy levels found in quantum physics' Band Gap Theory. That is why they each use the Quantum name.

First impressions

In our brief time with the G4 Quantum Display we were able to compare it with the G3 LCD and noticed an improvement.

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It's clear that the screen is improved with richer colours jumping out of the display. The G3, by comparison, looked almost washed out.

Brightness wasn't so obvious indoors but we imagine that will be more useful when outside. Or it may be more noticeable to battery life in the long run.

That Quad HD display was already good on the G3, so to have improved and still claim to offer decent battery life, LG has certainly done well.

Are you tempted by the LG G4 IPS Quantum Display? Check out our hands-on review to find out more.

READ: LG G4: Stunning camera with Quantum Display to show it off (hands-on)

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