Crystal clear

5 mins read

With 4K and 8K displays hitting the market, how can manufacturers continue to improve picture quality? By Elliot Mulley-Goodbarne

Do you know your LEDs from your LCDs? How about the pixel pitch of panels or the projected picture on partitions for presentations?

I’d hazard a guess that such technologies do not cross your mind when setting up in a board room, sitting down in your living room or looking up for a live replay at Wembley but, in certain scenarios, you may see a change.

Getting the sharpest display has been the focus of the likes of Samsung, Sony and TCL for years now and, as mobile devices develop the capacity to record in 4K resolution and broadcasters invest in ultra-high definition channels, the technology used to view such broadcasts is in increasing demand.

But we need to start off with a disclaimer: a 4K display will not always give you a 4K experience.

Strange to say, but the human eye can only see so much detail so, for a large format display (LFD) manufacturer like NEC, the pursuit of higher resolutions is somewhat futile.

“If we were to take our 0.9 pixel pitch display you are going to need a 330 inch diagonal display to get an 8K image” said solutions sales manager Mark Taylor, “that’s the problem. It needs to be for the right audience.

“That’s all dictated really by how far away people are sitting and what they need to see. The whole argument when it comes to a 4K screen is ‘how far or how close you’ll actually be sitting’, because there is a point, whether it’s 4K or HD, you’re not going to see any difference.

“The same goes for LEDs. You can only get the benefits of 4K if you’re sitting close enough so, if it’s for a general auditorium or advertising at a train station, for example, you don’t need that sort of resolution.”

Being an LFD manufacturer, resolution is not a concern for NEC. Granted getting the clearest picture is a priority but, as Taylor says, picture quality is only useful if it can be appreciated.

To appreciate the resolution, you need to be a certain distance away in relation to the distance between pixels. In other words, to find the minimum, optimum and maximum distance in metres someone has to stand to be able to read text and watch video off a screen, installers have to multiply the pixel pitch by 1.5 (minimum), 2.5 (optimum) or 6.5 (maximum) respectively.

Such calculations hold firm when it comes to slightly smaller LED displays. At Integrated Systems Europe (ISE) last month, Sony unveiled its Crystal LED technology which boasted a 4K by 2K resolution on a 4.8m by 2.7m display.

“The difference from the other LED panels is that the contrast ratio is 1 million to one” explained Sako Kageyasu, product marketing manager at Sony, “Other manufacturers have ratios of several thousand or 10,000 to one but our system is based on unique technology.

“We have our own factory building LEDs from chip to panel allowing us to eliminate extremely small areas of the display that cover less than 1% of the surface, its physical size is 0.3 square millimetres.

“At ISE, we wanted to demonstrate the technology in an application. We combined our interactive technology and put in a Kinect sensor to capture the movement of the audience and some of the interactive content.”

Kageyasu said that such applications of LED technologies and sensors are being worked on in the entertainment industry with the basic principle of eliminating the need to touch a screen by using motion instead.

In the world of retail, Sony has shown off this combination of technology in Asia on a digital signage system that allows audience members to view themselves on screen and to interact.

According to Rob Meakin, senior European product marketing manager for LCD Projectors at Sony, the ability to blend projections into one immersive experience is becoming more appealing to retailers as well as in spaces like museums.

“Both want to do digital AR. We have the ability to blend multiple projections to create this kind of entertainment for children’s museums and museums showing digital art.

“We see this in retail as well, but you do have a brightness issue to consider. Laser technology has the ability to last much longer, 20,000 hours for us with only 30% decline in brightness, not 50% which used to be the standard in brightness when it came to the lamps.

“Many manufacturers claim that their projector is protected to go for 40-60,000 hours. Sony’s can last for 80,000 hours, but the brightness level after 80,000 hours is probably not really fit for the application or for the environment the projector is operating in. But providing, cost effective, large display with edge blend, multiple projection in that retail and kind of museum entertainment is becoming more and more popular.”

Maintaining quality

With laser projection technology the quality of the picture has improved with Panasonic showing off a tri-laser RGB set up on a black canvas to improve the contrast output.

However, Taylor pointed to a reliance on a dark environment to get the best results as one of a number of concerns.

“In the retail environment, projectors will need to be on continuously for a long time, and that’s a challenge. You have a maximum life of 20,000 hours which is a couple of years. Then you have the issue of maintenance - some sealed optical engines do need regular maintenance. Finally, brightness levels are a concern because most retailers want a bright environment.”

Health and safety concerns are another issue, with Taylor citing potential retina damage if someone walks in front of a projector that is too bright.

Turning to the future, how will displays improve? Meakin says that, when it comes to Sony’s projection R&D, “the number one issue will always be colour clarity and producing the correct image.”

On the panel side Taylor says that improvements in picture quality have obstacles to overcome.

“There are limits when it comes to pixel pitch at the moment. We are going to have a 0.9 [pixel pitch], other manufacturers have a 0.4 but when you start going down that route you’re getting into the realms of cost. For a 0.4 you’re probably looking around £14,000 pounds a square metre.

“The industry is starting to use other technologies like mini LED, flip chip and four in one to bring those pixel pitches down but, again, they are cost prohibitive at the moment.”

Taylor adds that those high prices are due to the manufacturing costs of screens; the attention to detail needed in setting up displays; as well as the necessity to source diodes from the same manufacturer, or bin, to ensure consistent colour shades.

“When you manufacture screens, we make a guarantee there’s the same shades of the red, the green and the blue. So you can get top tier diodes for a screen from us for £50,000 for instance. You might get a Chinese manufacture offering what appears to be something very similar at half the cost, but because that cost is loaded into the diodes, they’ll get something from a different vendor but the colours won’t be quite the same which means after years, because diodes degrade, there will be a mismatch and a significant drop off in performance.

“Diodes are expensive, the manufacturing process is expensive and shipping them is expensive as is installation.

“It’s not just about hanging a screen. You need special installation crews to make sure that the structure that they go on is flat. To give you an idea, to ensure that a hundred and 10 inch screen, which is probably one of the smallest ones, is hung on a wall that is flat you’re looking at between £2,000 and £3,000 in costs.

“So this is where all the costs come from. But once it’s in and it has got through its bedding in period, it could be rock solid for years. They don’t have to worry about it.”