Originally Posted by barth2k
Does oled tech have inherent flaws that cannot be overcome without prohibitive cost, as in we can make a good lcd but we need 1000 dimming zones cost? The good news is out of the gate oled already edges out the best plasma in blacks and contrast. The other good news is oleds will have to improve much much faster than plasma did to survive. I would feel better if there were more than one player and the one player weren't LG.
The short answer is a qualified *no*. Of *course* OLED has limitations (or you may call them 'flaws'). ALL TECHNOLOGY has trade-offs (even Plasma). I am NOT talking about tradeoffs in visible performance, either. I am talking tradeoffs down at the engineering level. For example, some of the trade-offs for Plasma have been (and still are), difficulty to drive (high-voltage drive electronics are complicated) and difficulty to manufacture. Great strides have been made in the last 10 years in plasma drive electronics, overcoming much of the cost and power inefficiency barriers. Panel manufacturing made great strides as well, improving yield while decreasing cell size and cell longevity. However, as cell size shrunk, the panel cost started going up again. Plasma panel manufacturers are NOT willing to burden the cost of future TV's with the high cost to produce a UHD plasma panel at the 50-70" sizes. The simple fact is that other panel technologies (LCD, OLED) are cheaper to produce and increasing pixel density does not add a substantial cost to the panel.
Now let's talk about OLED limitations or trade-offs:
1. emitter life (on the panel itself) -- This is a major issue, that, I believe, will be incrementally improved for many generations. Panel manufacturers have a vested interest in improving this aspect of OLED technology -- not primarily to make TV enthusiasts happy, mind you. Instead, there is great motivation to improve organic LED longevity because of so many other lighting applications. As improvements are made, the chemistry will make it into the panels.
2. emitter brightness (on the panel, and on the pixel drivers) -- This is somewhat married with emitter life (listed above). There are a number of factors that affect the luminance decay of the OLED emitter, including outside radiation (IR) and stress to the P-N junction of the emitter through heat, electron migration, etc. Generally, as chemistry is improved to address emitter life, we can drive the LED's 'harder' to achieve greater brightness (we don't have to drive them harder, but as life at a given brightness level exceeds the lifespan of the typical consumer purchase interval, higher brightness becomes an option). Besides chemistry, the other factors that affect brightness are a) heat dissipation and b) drive capability.
a. Heat dissipation is critical because it defines how quickly the heat can be moved away from the emitter. As an analogy, some of the largest strides that have been made in the last 5 years with LED lighting (replacing incandescent) are related to improved heat dissipation of the LED's, thus allowing higher wattage-equivalent bulbs. I believe there will be incremental improvements with heat dissipation, but I think they will not advance as far as chemistry improvements simply because of potential added manufacturing costs.
b. Drive electronics are key to several factors of OLED performance -- these electronics are not integral to the panel (yet) but they determine the ability to modulate each pixel as needed as well as potential pixel brightness. The current crop of OLED's use the simplest drive scheme (some call it sample-and-hold). Basically, this means that each pixel is driven with a modulated current defining the pixel's current brightness (defining the overall RGB color of the pixel triad) for the duration of the frame. This is the most efficient, because, for example, if I want to turn all pixels on 100% (white static image), each driver transistor needs to be capable of a set current (or power output capability) equal to that of the OLED's full-scale 100% duty-cycle current. This current might be around, say, 5 milliamps per pixel. Contrast that with the drive electronics I believe we will see 2 or 3 generations down the road, which will be capable of 'scanning' the display. Scanning is a simplification here, but basically means that I can 'pulse' a pixel for shorter periods of time than the entire duration of the frame while *still* retaining the same perceived brightness. This has been done for years on scanned LED displays, and the understanding of the human eye's brightness perception versus pulse width/brightness are well understood. HOWEVER, scanning presents challenges in drive electronics and power supplies. For example, say I now want to drive the pixel at 10% duty cycle (this is ignoring the sub-modulation controlling the pixel intensity for color depth) but keep the same brightness. In a simplistic case, this means I must now drive the pixel *10 times harder*, or at a current of 50 milliamps in my example. So, I need a larger transistor, and perhaps I need a transistor with a lower 'on' resistance to avoid more heat. Even worse, if I choose to pulse all the pixels on the display at the same time at this 10-times factor, my power supply must be able to handle 10 times the instantaneous current. While all of this will be challenging (and add some possibly substantial cost to the electronics), these advances will come in future driver IC designs specific to OLED and in many ways are TRIVIAL compared to the complexity of the electronics that had to be designed to improve plasma.
3. Emitter structure -- it is hard to predict how this will evolve because I believe that some of these changes haven't even been discovered or though up yet. The emitter structure today requires filtering in front of the pixel to hide part of the anode. I believe this filtering is likely the cause of some of the color aberrations that we see when viewing off-axis. Much of this is irrelevant to OLED lighting (which as I said I believe will be the overall driver of advancements in the technology). I believe we will see improvements that help image displays *if* they do not add substantial costs. As I said in a post elsewhere, TV manufacturers have to think long and hard these days about adding much cost to their displays when the majority must sell in the sub-$1000 commodity bloodbath -- The past decade of [the majority of] consumers who were so excited to have their first large flat panel and plopped down $3000-$5000 for it is no more.
MY OPINION (it is an educated one, mind you, since I work close to these technologies) is that OLED offers one of the best infant technologies to add upon. For simplicity, I would say that the OLED TV's we are seeing today represent a 2nd or 3rd-generation display. Throw another 5 generations on top of what we already are seeing and we'll have something to rave about.