The LED videowall rat race

Paul Milligan finds surging demand for LED videowalls that are dropping in cost and pixel pitch. But, how low either parameter can go, depends on factors sometimes out of product manufacturers’ control.

There is little doubt that LED videowalls are soaring in popularity right now.   

Alongside wireless presentation systems  it is the most talked about product in the pro AV market across EMEA. The market used to consist of very basic 20mm pixel pitch tiles, which only interested a small group of clients in high profile locations (Las Vegas, New York, Dubai and London, for example).  Of those wanting a high resolution  product (what was sub-10mm pixel pitch, and is now 3 or 4mm) it was a product only affordable for those with deepest pockets in the US, the Middle East and parts  of  Western Europe.  A combination of rapidly improving technology and falling prices has seen it installed more frequently and in a far wider range of applications that ever before, and the product has reached mass acceptance.  

Data from Futuresource shows the narrow pixel pitch (NPP) LED market (defined as 3mm pixel pitch or less) was worth $678 (€617m) last year, which was three times both the volume and value reported in 2014. The data not only backs up the rapid ascent of the LED videowall in recent years, but predicts this will be a continuing pattern for years to come.  This year NPP LED tiles will  make up 19% of the total videowall
market, with LCD narrow bezel panels making up the majority with  64%  (rear  projection videowalls make up the rest of the market with 16%).  By 2020 the gap  between LCD and LED will close dramatically, with LCD marginally ahead with 48%  of  the market and LED just behind with  44%.  Given the low  prices  of  LCD  panels out there  in  the market, this is quite some shift we are seeing.  

With regards to the technology inside the LED tiles, all  the  major  advancements  have come in  one  area:  resolution.  In  the  last  five  years pixel pitches have fallen from 10mm to 6mm to 4mm.  And in the last 18 months that has sped up, as Koen Werbrouck, product manager, Barco demonstrates: “Barco released a 3.5mm product in 2005, then it took five years to get to 2.5mm, when Leyard introduced a model in 2010.  Then it took another three years to get to 1.9mm and 1.6mm.  Now we are in a yearly pattern and have moved  from  1.2mm  to  0.9mm.”   

With  greater resolution comes an increase in cost and fragility, but at the moment  it  seems to  be  a  contest, Werbrouck dubs it a ‘rat race’, to see who can win the ultimate goal of getting to 0.1mm.  As we look to the future of LED tile technology is 0.1mm a realistic possibility or just an unnecessary dream of a marketing team? “Is there a need to go to 0.1mm? I’m not sure.  We also don’t have the physics to do it.  The size of the LED diodes is not something we control.  Going to 0.1mm means  the  LEDs  will  be  0.05mm,  which  is  not reachable  for  the  moment,  and  also  can’t  get the brightness we want at the moment.  Is there any demand in the market for it? Because your eye can’t see it a few centimetres away, so the limit is the eye.  Is there a need to go further? I’m not sure,” says Dominique Denis, LED market development  manager,  Christie  EMEA. 

He  also hinted  at  a  possible  divergence  and  end  game other  manufacturers  were  looking  at  moving toward. “We are focused on sectors like control rooms, but some of our competitors are targeting the mass market of television.  It will take years, but their plan is to replace your LCD or OLED tv with LED.”  

According  to  Gary  Feather,  CTO  at Nanolumens,  LED  pixel  pitches  will  be  driven by  need,  advantage  cost  and  technology.  “Current LCD and OLED TVs have a pixel pitch at  0.35mm  and  0.7mm.    I  expect  based  upon size and viewing distance, discrete LED solutions where tiling is required will not have a need to exceed 0.8mm anytime in the next five years for commercial applications." 

What reasons does he give for this prediction? “The eye limitation is based upon the fovea (the centre of the eye’s sharpest vision and the location of most colour perception) and the viewing distance. The specification for best viewing distance  (when  you  cannot  see  pixels anymore) is 1000 to 2000 times the pixel pitch.  TV viewing is set at 3x the picture height for HD, which for a 60-in TV is 30 inches and therefore about  90  inches  away,  or  7-8  feet.    UHD  is half  that  distance.”  The  consensus  among  all the  vendors  we  spoke  to  was  that  the  limit  of the eye would be the limit of LED pixel pitch, with  a  figure  of  around  0.6mm  marked  as  the eventual end goal. 

“The viewing point of 0.1mm is really for screens for mobile phones, but even then there are better technologies than LED to do that,” adds Werbrouck.  As highlighted above by  Feather,  money  is  also  a  factor  slowing  the advancement of LED, and will see this product segment  move  in  slow  rather  than  big  steps.  

“The  price  will  limit  development,  it’s  getting lower and lower every year.   6mm cost €4,000 per sq m 10 years ago, now it’s €3,000.  If you look at the same curve, it will be affordable in three  years,  but  for  now  it’s  high,”  says  Denis.  

Market forces, especially in technology, are hard to  ignore it seems. “In  our  opinion  the limit will be defined by the market and the demand.  If  customers  need  less  than  100-in  they  will choose a flat panel display, if they need more the advantage  lies  with  LED,”  says  Kageyasu  Sako, senior manager, product planning, Sony.

There is another reason for this single-minded focus on resolution suggests Werbrouck; “Some companies only focus on LED, so they want this technology  to  compete  with  rear  projection or LCD panels, where the resolution is much smaller.  We know  people  are  doing  research  into  chip on-board and microLED but we don’t feel these technologies are ready for mass production.  It’s a  market that’s moving fast,  but  it  will  come to a point where it needs to stabilise, and new technologies need to be found to really go to the small pixel pitches.”  

As mentioned before, the lower the pixel pitch the more brittle the tiles become, leading some buyers  to  be  wary  of  sub-3mm  products.  Is there a future when even 1mm or 2mm tiles are robust enough for the most demanding of pro AV applications such as rental and staging? The market is sceptical. “Up to 2.5mm pixel pitch the diode is 2x2mm, so the soldering on LED tiles is very strong, below that it is very fragile.   It’s very hard to move to 1.6mm or 1.9mm without any damage being caused,” says Denis. 

While others believe it will be overcome, but it’s going to take time.  “There are different approaches to tighter pixel pitches that range from SMD RGB LED to COB and finally to uLED. Each has great value at particular pitch and size; and each offers its particular advantage for rework, yield, durability, cost and infrastructure,” says Feather.  

When you look at other display technologies, advancements have come in the form of touch capabilities,  advanced  audio  options,  gesture control, or facial recognition. Will we see any of these in future LED products? It seems unlikely, except for clients with very niche requirements. The  cause?  Physics,  as  Werbrouck  explains. “Everything is possible, and we do get requests for  touch  systems,  but  it’s  mainly  the  viewing distance that’s the barrier.  If you have a 1.6mm LED videowall, you will have a viewing distance of 2-3 metres from the screen, which means you can’t use it  in  combination  with  touch.”   

The same  reasoning  applies  to  gesture  control  or facial recognition, to view it well you need to be a few metres away, which makes those actions difficult.  Another  block  to  gesture  control, audio or facial/gender recognition systems is the modularity  of  LED  tiles.    They  are  more  often than  not  used  in  combinations  of  2x2  or  2x3 etc so the only way to get a camera or speakers is to attach it behind the tiles or to the outside frame or the very top, which can ether ruin the aesthetics or may not be possible if the videowall is housed inside a wooden or plastic frame which has been designed to fit exact square edges.  

If  you  have  a  videowall  you  are  going  to need  something  to  drive  the  content,  and  that something  is  a  video  processor.    More  often than not each videowall manufacturer will have its  own  supplementary  video  processor  product too,  Christie  has  Spyder,  Barco  has  TransForm, eyevis  has  Netpix.    But  is  there  the possibility we  could  see  LED  offerings  built  with  more intelligence  inside  each  tile  so  integrators  and consultants wouldn’t need a separate processor?

Again, it seems unlikely.  “At the moment all of the processing is outside, if you put it inside, the way you address all the signals will have to change dramatically,”  says  Denis.    “With  more  complex electronics  inside,  this  will  increase  the  cost, because you will have to duplicate the intelligence inside each tile. With a wall of 100 tiles, instead of having one intelligent processor at the bottom of  the  screen  you  will  have  100  boards  inside providing the intelligence, which will cost more.  

There will have to be a huge decrease in the price of the intelligence you will put in the board to be able to spread it everywhere.”

Apart  from  perhaps  Silicon  Core,  the  energy efficient properties of LED tiles is a subject often sidelined.  Could we see any advancements here? Sadly, it seems the opposite is happening. “Our experience  is  that  energy  efficiency  has  gone down  over  the  years,”  says  Werbrouck.  “If  you look to the LEDs we were using five or ten years ago  they  were  much  more  efficient  than  what we  see  today,  and  I  would  put  that  down  to the pixel pitch ‘rat race’.” How have we got to a place where this is acceptable? “It is very rare to choose an LED tile over a competitor on energy efficiency, they ask for brightness or colours or video  rendering  first.    For  most  of  the  people who can afford to have an LED videowall in their lobby the electricity bill isn’t their main concern,” says Denis.  

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