LG shows what it can do with LCD ‘Super UHD’ with ‘Nano Cell Technology’... what’s that exactly?
It is very easy to get so smitten with OLED technology that one neglects to pay as much attention as one should to what remains the entirely dominant TV panel technology — LCD. Indeed with the price discrepancy between the technologies not likely to disappear any time soon, it’s clear that LCD is going to be around for quite a while.
Here we have 65-inch LCD in the form of the LG 65SK8500PTA UHD TV, one of the company’s ‘Super UHD’ range. Indeed, it’s second from the top of that range. And it sells for $2200 less than the same-sized entry-level LG OLED C8 model which we reviewed last issue. How does it compare?
Let’s be clear, there is very little difference between this TV and that OLED except for that one thing: the display panel, and also some changes to the panel driver technology (principally, the new OLED range uses LG’s Alpha9 image processor, while this TV uses its Alpha7).
So, to the panels. LG.Display’s OLED technology — which is used, as yet, in all consumer OLED TVs, not just LG’s — uses red, green, blue and white subpixels in each pixel. Each generates the colour natively. The RGB elements are relatively narrow-band in their light production, generating light wavelengths fairly tightly lumped together, with little spread into other colours. The white is used to boost output levels, and take the load off the blue sub-pixels, which are thought to wear out faster than the other colours.
Traditionally LCD TVs, on the other hand, use subpixels which have red, green or blue filters over them. Behind the LCD panel is a broad spectrum light, and the filters in
the subpixels block the unwanted wavelengths. Various enhancements have taken place over the years. Most obvious have been improvements to the backlight: breaking it up into chunks so that different parts of the screen can be at different brightness levels.
But when it comes to colour, the race has been on to improve the colour gamut, the range of available colours. It is gamut that is enhanced — extended — if the reds and the greens and the blues each consist of a narrow range of wavelengths, rather than bleeding across into the wavelengths of the other colours. This can be achieved in two ways. One is to change the backlight. Another is to improve the colour filters.
Quantum Dot technology, as used by Samsung, TCL and Hisense, takes the first approach. It uses what you might call ‘tuned’ nano-particles to produce light in relatively narrow bands of the primary colours.
It seems that LG is taking the second approach. Last year the company introduced a new technology, or at least a name, for its premium UltraHD TV panels: Nano Cell Technology. As can often be the case, details on this are a little sketchy. LG says that “Nano Cell Technology uses nano particles that absorb unwanted light wavelengths and enhance the purity of the red and green colours displayed on the screen”.
Of course absorbing unwanted light wavelengths is what the colour filters do have always done. But a fascinating paper by Peter Palomaki and Matthew Bertram was published a few months ago by Palomaki Consulting (we’ve linked to it at avhub.com.au/ppmb). That business consults specifically on nano technology, including various materials and quantum dots. The paper shows the output spectrum of a Super UHD TV and notes certain characteristics that suggest the addition of a new filter designed to remove light from the area around 580 nanometres. That’s the space between green and red. And it happens that this accords with LG’s description.
The paper quibbles with LG using the ‘Nano’ term, saying it’s merely a ‘molecular dye’ (they dug into LG’s patents to research this) with particles on the nanometre scale. But nano has become a widely abused term outside its strict original application. What matters is that they consider this technology pushes the gamut of the Super UHD panels from 82% of the DCI-P3 colour space to 92%.
Connections & smarts
To recap briefly, this TV has four HDMI inputs, two USB connections. It supports all the good stuff like BT.2020 colour, HDR, Dolby Vision and Hybrid Log Gamma, though not the new HDR10+ available on some Amazon Prime material (unsurprising, this, since HDR10+ includes Panasonic and Samsung but not LG in its consortium).
You can time-shift TV with USB storage. You can feed sound back to AV receivers and higher-end soundbars via HDMI using ARC.
The panel is reasonably thin at a little over 65mm, but it clearly isn’t going to challenge OLED on that front. The reason for the thicker panel is the use of a real array of LEDs behind the LCD. LG calls this Full Array Dimming.
The TV includes LG’s latest version of WebOS. Combined with the Magic Remote, it remains the most effective smart TV interface in my view. It has been enhanced this year with LG’s ThinQ AI features. These attempt to improve things like voice searches by taking into account context. If you ask about an actor, and that actor’s in a movie you’re currently watching, the TV will try to take that into account. Or, rather, LG’s ThinQ servers back in Korea will.
If there was a difference on the general area of smart TV functionality between this one and the most recent OLED, it escaped me. The basic WebOS layout is the same, only slightly tweaked from how it first appeared some years ago. But now the processing power has been enhanced so that it’s far snappier, with few functions leading to a pause before responding, and those for only a few seconds.
I was able to feed it Ultra-HD video — although it stuttered with 100Mbps stuff — music including in high definition FLAC format, and photos. Photos were handled well, with maximum colour and detail resolution delivered. That functionality is via DLNA. The TV does not support Chromecast.
The TV has dual-band 802.11ac Wi-Fi in addition to an Ethernet connection.
In most circumstances the picture performance delivered by this TV was first-class. In some
circumstances it’s better than OLED. Those circumstances are when you’re watching in a well-lit room. When you’re doing that, ultimate black levels are less important. The brighter the room, the lower their importance. What instead becomes important is brightness levels, and it was clear that this TV can deliver considerably higher levels of that than LG’s OLED TVs. My eyes are accustomed to an OLED, and the first few times I switched this TV on, I almost winced. Not in pain or displeasure, but just because the brightness was higher than expected.
Not that any nasty tricks are employed to achieve that. With the standard picture settings there was no crushing of white levels up against the maximum capability of the panel. Using a test pattern, LG seems to have retailed subtle brightness graduations right up to 1800 nits, although it’s doubtful that it can actually go that bright.
The colour was truly impressive. Billy Lynn’s Long Halftime Walk was stunning, particularly the scenes within the stadium where colours were bold. The sense was one of hyper-reality. Colour graduations were smooth. Where subtlety was called for, it was delivered.
Deinterlacing and motion smoothing were up to LG’s high standards. Generally 576i/50 and 1080i/50 content was presented correctly, occasionally tricked only in the most ambiguous scenes. I’d be perfectly happy watching 1080i and 576i output from a set-top box with this TV. The standard ‘Smooth’ motion smoothing is a touch too much, generating visible distortion. But if you choose the User setting, and set ‘De-judder’ to around 4 on the scale up to 10, you get significant benefits with minimal distortion.
Now, black levels. I started by playing a UHD LG clip it developed specifically to show off OLED technology. In other words, to show off black levels. Localised dimming is of little use with it because there’s a lot of black, but also a lot of bright elements interrupting it. With this TV, viewed in a dark room, the brightness was initially stunning, making the irises shrink rapidly. But as things settled down, it was clear that the blacks were relatively muddy, detracting a little from the impact. Later I watched a movie and as the traditional white-on-black credits rolled, I picked up the TV’s remote. The on-screen arrow jumped to life, and as it moved across the screen, this very large glowing area followed it. I put on some test patterns. With a full black image, the TV demonstrated that it could control its backlighting all the way down to zero. There was nothing to distinguish this TV from an OLED. But then I put on a test ‘pattern’ which consists of a full black screen, except for two single white pixels in the display. Now the blackness was replaced with two very large glowing areas. It looked to me that the array consists of four columns of backlights, with a stack of eight individually controllable areas in each. That makes for 32 lighting zones. I’m confident about the number of columns, less so about the stack of rectangles in each column. So, yes, there is a backlighting array. But it is so low in resolution it is of quite limited value.
The official energy rating of this TV is 4.0 stars and 458kWh of energy use per year. That’s less than 83% of the energy consumption of the same-sized OLED, despite it being rather brighter. Those interested in saving energy costs and emissions may want to take that into account. I found it interesting because we can mount all kinds of theoretical arguments why OLED should be more energy efficient. After all, OLED only lights up the pixels which are in use, while the LCD backlight typically lights up a lot more of display. But the reality is that LCD has been under development for a much longer time, and this shows in a number of ways. Perhaps OLED will catch up in energy efficiency — the OLED65C8 uses 96% of the power of the OLED65C7 — but it’ll take a while.
If you can afford it and you view in a darker environment, OLED remains the way to go. But if you usually have lights on, save yourself a pile of money and look at the LG 65SK8500. Better still, step up to the SK95 models — a bit pricier but with “Full Array Dimming Pro”, almost certainly a higher backlight resolution than 32. Stephen Dawson
LG SK85 4K LCD TV
▲ LG’s Nano Cell Technology has nothing to do with the backlight array, as some might guess. Indeed the backlight array is fairly coarse — we think 32 lighting zones in total — so that while there is excellent control of levels down into blacks, small areas of light on dark backgrounds create large glowing areas, as shown here.