New Display Developments Hold Potential for CAD Applications20 Jan, 2016 By: Alex Herrera
Herrera on Hardware: Curved, 4K, HDR, and other technologies all promise better viewing experiences for professional users — but which will go mainstream, and which will fade away?
Several months back, this column took a tour through current display products and technologies to help CAD professionals create the most effective, productive, and economical display configurations possible. This time around, we'll look forward at emerging display products and technologies that will likely factor into the choices you'll make in CAD monitors down the road.
Some advancements, including increasing display resolution and color precision, are familiar and predictable. Another attempts to improve on a quality metric that's been surprisingly stagnant for some time: contrast. And finally, others look to change the paradigm of conventional displays with new takes on form and function. Some of these coming innovations will stick and eventually become commonplace, while others will never extend their reach beyond specialized niches. Some may never gain a foothold, and will fade away entirely. Which outcomes are likely for the various technologies on the horizon? Let's explore.
4K and Beyond: Passing the Limits of Perception
The most predictable axis of display technology evolution, pixel density, will see another step forward in the near term. Spurred by advances in display and semiconductor technology, resolution has climbed steadily over the past few decades, from 640 x 480 to 1,024 x 768 in the 1990s, up to 1,280 x 1,024 in the ‘00s, and this decade pushing up to 1,920 x 1,080. The next stop on the trajectory is 4K, which is typically around 3,840 x 2,160.
The 4K buzz has been building over the past year, primarily promoted by TV manufacturers looking to provide a sorely needed market pull, now that demand for big-screen Full HD has waned. Professional monitor manufacturers are on the 4K bandwagon as well, and prices will assuredly drop over time to a high-volume sweet spot, making it all but certain that every CAD desktop will transition to 4K in the not-too-distant future.
It's tempting to assume that resolutions even higher than 4K will all one day become ubiquitous. After all, that's the standard path followed by all silicon-driven products right? Things always become faster, cheaper, and better. And we'll eventually accept them, buy them, and find them valuable or even indispensable, even if we don't at first think we need them. But that incessant push forward doesn't apply when an incremental technology improvement crosses a critical threshold: the limit for humans to recognize that improvement. For example, it turns out there's not much need to exceed 5–7 ms liquid crystal display (LCD) response time, because human response systems — comprising our eyes and brains — cannot "refresh" any faster than that.
Similarly, display resolutions have already moved past the point of diminishing returns — at least given typical screen sizes and viewing distance — and will one day reach the limit of our visual system's ability to distinguish a difference. So where does 4K stand with respect to that limit? The whole point in naming the display “Retina” is that its dot-pitch is such that the human retina can no longer differentiate individual pixels when viewed from a foot or so away. Now, let's correlate that dot pitch to a typical desktop setup, where the display might be 30" from your eye. It turns out that at that distance, a 4K resolution on a 25" display essentially matches the dot-pitch of a retina display held around 10–12" from your eyes. (the website IsThisRetina.com provides an enlightening tool to calculate and compare figures).
Given that comparison, then, not only is 4K on a 25" desktop display already past the point of diminishing returns, but going further holds little to no value, unless the screen gets bigger or our eyes get closer to it. And screens are unlikely to grow much in size for most CAD users, for two reasons: desk space isn't growing (it's more likely to be shrinking), and for many, using two (or more) smaller displays side by side can be more effective — and even more economical — than going to a monolithic screen. The bottom line is that 4K will eventually thrive, but unless our viewing habits or display configurations change, there won't be much reason to push beyond that level of resolution, at least not for a traditional desktop work environment.
In Pursuit of Better Contrast
Increasing pixel density is one avenue to improved image quality, but it's far from the only option. Doubling dot-pitch (i.e., doubling resolution in the same size display) achieves finer-grained pixels, but display engineers are working to produce more precisely lit and colored pixels as well. Dialing up contrast and color precision are two such efforts.
As I noted previously, when talking about contrast, what most users really care about is static contrast. (For more on the difference between specs on static contrast and the mostly confusing dynamic contrast, check out that previous column, “It’s Time for a CAD Monitor Makeover.”) The contrast available in moderately priced displays has flattened at around 1,000:1 (i.e., white is 1,000 times brighter than black), leaving a whole lot of room for improvement and spurring new takes on existing LCD technology. Just as we've gone from standard twisted nematic (TN) to in-plane switching (IPS) technology as the basis for all mass-market LCD-based monitors, we're seeing signs of another potential transition: away from IPS and toward vertical alignment (VA) technologies. And driving this transition is the pursuit of better contrast.
Let's back up a second for a quick review. All these acronyms represent implementations of tried-and-true LCD technologies, in which a pixel's crystals align to changes in voltage to polarize the liquid, either allowing light to pass (white) or not (black) or somewhere in between (shades of gray). (As a worthwhile aside, that light emanates from the display’s backlight. These were typically compact fluorescent lamps (CFLs) in the past, and now are almost universally light-emitting diodes (LEDs). That is, when a vendor markets an “LED” monitor, the vast majority are talking about LCD displays that incorporate an LED backlight — this is very different from the LED technologies used in many smartphone displays, in which each pixel creates light via an LED).
IPS puts a slant on simpler, traditional LCD approaches by dramatically improving the viewing angle over what conventional TN technology provides. We've all experienced the annoying loss of quality — up to the eventual loss of the entire image — as our view strays from head-on to an oblique angle. IPS remedies that problem with a far wider viewing angle and is the major reason why the technology has crossed over to the mainstream as production costs have declined. A TN display might see noticable degradation in quality — washed out colors, for example — after straying from head-on by even 20 to 30 degrees (judged by eyes, not by specs); IPS viewing angles, on the other hand, retain quality at much sharper angles (the spec is typically 178 degrees). IPS has its own Achilles’ heel, however, which it shares with conventional TN: poor static contrast. IPS allows more backlight “bleeding” — meaning the LCD’s backlight penetrates through pixels that are supposed to be off, making black areas disappointingly bright and capping achievable contrast around that 1,000:1 ratio.
That's where VA technology comes into play. VA technology has actually been around for a while, but only recently has it seen significant improvements (at least in terms of mass-market potential) to challenge technologies like IPS. By reducing backlight bleeding, VA has always offered significantly superior static contrast ratios — three times or more of IPS — but it’s had its own tradeoffs in viewing angle and response time. In recent years, however, display vendors have made advances in VA with various vendor-specific incarnations of PVA (patterned vertical alignment), mitigating VA’s weaknesses and opening the door for a new generation of displays to offer viewing angles closer to IPS but with far superior contrast. New-generation VA approaches such as Samsung's SVA are showing more promise, making it possible that IPS’s days as the default choice for CAD displays may be numbered.
Looking even further down the road at candidates for mainstream adoption is one particular technology that many are waiting for, and one that will provide the ultimate improvement in contrast: organic LED (OLED). Because OLED emanates light at each pixel location — rather than letting it pass from a backlight source — OLED offers contrast that’s dramatically superior to LCD technologies, theoretically infinite, as "off" (black) is truly off. However, while it is becoming commonplace now in small displays (primarily phones), OLED has yet to cross over in large displays. Because it can deliver bright, high-fidelity, high-density displays, many anticipate OLED’s arrival as the end-all in desktop, laptop, and living room displays.