Power consumption - Page 37

When the Zune HD launched, there was an interesting blog post on the Apple-Insider site. They wanted to 'smash' five myths on the Zune HD, and one of the Myths is about the OLED display. They claim that OLEDs consumer more power than LCDs, are less bright, do not last long and are bad in direct sunlight. Barry Young from the OLED Association has responsed in his own blog post - basically saying that OLEDs look better, have even longer lifetime than most LCDs and consume less power.

Barry also says that when Steve Jobs first saw an OLED display, he said that's the best looking display he had ever seen. We're all waiting for Apple's first OLED product...

The only truth in the Apple-Insider article is probably about the sunlight visibility. We have discussed this issue before, and Zune HD users are indeed complaining.

The Zune HD has actually got great reviews, and it was sold-out within days of its launch. Some consider it as the first real competitor for the iPod touch, and most people love the OLED display. The Zune HD costs 290$ for the 32Gb version, and 219$ for the 16Gb.

In June 2008, I interviewed Corey Hewitt and Dr. James Buntaine from Kodak OLED Systems.

Mr. Corey Hewitt is the co-general manager, operations manager and VP of Kodak OLED Systems. Dr. James Buntaine is the second co-general manager, and also the CTO and VP.

They were kind enough to send us an update on Kodak's OLED program and market outlook:

Kodak OLED Technology Update & Advancements

Kodak expertise and experience lies in material discovery, organic layer design, mechanistic understanding, image science, panel/module design, and manufacturing technology. These key value drivers associated with the Kodak technology, know-how and patents, maintain Kodak as an industry leader in enabling both the OLED flat-panel display and OLED solid-state lighting industries. Provided below are selected key areas technology and Kodak accomplishments:

All TV makers are now offering a green TV. Usually they still sell their normal TV, and the new green model is offered at a premium. Some use LED technology to reduce power consumption, and some use all sorts of ideas like an optical sensor that knows if you leave the room and shuts down the screen (but not the audio), or an 'eco-mode' button that reduces brightness by 20%.

These are nice ideas, and we definitely want to see less power-hungry TVs. But is this really financial sound?

An Israeli newspaper has made the calculation, assuming that you watch 4 hours of TV a day. For example, Samsung's 40" LED TV consume almost half the amount of electricity when compared to their normal 40" LCD TVs (95W/h vs 175 W/h). The cost is more than double. The saving? around 1.2$ a month in the electricity bill (in Israel 1 KW costs around 12 US cents). In any case, it will take over 166 years to offset the difference in price!

For Plasma (PDP) TVs, the savings are more substantial. For example Panasonic's new 50" Plasma, which uses their neoPDP tech consumes 269 W/h compared to 555 Kw/h in an older model. They actually reduced the price, too. The monthly power saving is around 4.7$.

Obviously the new LCD TVs offer a better viewing experience, and new models always cost more than old models, but it seems that the money saving is minimal. 

OLED TVs will consume even less power than LED LCDs, but will be priced at a premium - at least until manufacturers can actually make them cheaper than LCD TVs (which should be possible, as they have a more simple design). I'm guessing that OLED TV companies need to focus the marketing on the image quality and thinness rather than the power saving of OLEDs...

OLED is an emissive display technology - which means that it emits its own light, in contrast to a reflective display - which uses an external light source - an ePaper display for example, or an LCD which is a display that blocks light from a backlight unit.

OLEDs are bright, and provide great image quality, and as of 2021, these displays perform very well under direct sunlight.

But this was not always the case. In early AMOLED displays, sunlight readability was very poor. The 2008 Nokia N85 for example, one of the first products with AMOLED displays, behaved very poorly in direct sunlight, as can be seen in the image below:

The problem in early AMOLED displays resulted from reflectance from metal electrodes in addition to relatively low brightness. Display makers however, soon upgraded their OLED displays to increase performance. Helped by new technologies and materials, OLED displays quickly overcame the sunlight readability problem. Today OLED displays actually perform better than the best LCDs in direct sunlight.

For more information on OLED display technology click here.

The CombOLED project together with CEA-LETI (a French research laboratory) has developed an efficient transparent white OLED. The Small-Molecule OLED has a 5 x 5 cm2 active emitting area, which is deposited using thermal evaporation and encapsulated using ultra-thin layers.

The OLED is 65% - 70% transparent, and emits light from both sides (bottom and top emission). The white luminance reaches 1000Cd.m² at 4 and 4.6 volts for bottom and top emission, respectively. The white OLED efficacy are respectively 11Lm/W and 3Lm/W at 1000Cd.m² for bottom and top emission, which leads to an overall efficiency of 14Lm/W. In this case the color coordinates are (0.40, 0.42) and (0.35, 0.42). When they create the same color for both sides, the efficiency is 10Lm/W and it's only 65% transparent.

The researchers are still working on greater efficiency and improvement of the permeation properties of the thin encapsulation layers.

UPDATE: Here's a video clip of the CombOLED transparent white OLED panel.

Universal Display Corporation have been awarded a $1.65M two-year contract from the US Department of Energy to demonstrate thin, efficient white OLED lighting concept for under-cabinet applications.  

UDC will deliver several under-cabinet lighting units to the DOE. each unit will have five 6"x6" white OLED panels, with a system efficiency of over 60 lumens per watt which is comparable to existing under-cabinet systems. The OLED lamps will be much thinner than anything available today, enabling new design concepts, and will make for easier installations.

UDC are also working on ceiling lamps, together with Armstrong, and have recently showed a video with the new 24" OLED lamps.

Scientists from the independent Stanford Research Institute (SRI) have design a new efficient OLEDs using cavities - in fact the new OLEDs are five times as efficient as standard OLED (i.e. five times as much light per watt consumed). The green COLEDs (Cavity-OLEDs) achieved 80 lumens per watt, and the blue ones 30lumens per watt. 

They used Polymer-OLEDs provided by SDK, and the team says that they are ready to make white light (by mixing red, green and blue OLEDs), and estimate that products based on this new tech could arrive as soon as next year.

Showa Denko K.K. (SDK) has developed new, efficient, coated phosphorescent-polymer-based OLEDs. The new devices achieved about 40% in light output (the quantity of light emitted from light source, divided by electric power consumed.) - which they claim is the highest level in the world. The efficiency is 30 lm/W, and the lifetime is approximately 10,000 hours.

SDK says that OLED made by coating is attracting keen attention because it consists of a few layers formed by coating polymer without the use of vacuum, providing the opportunity for substantial cost reductions and for the production of large
area-emission panels in the future.

CDT is one of the leaders in OLED research, focusing on Polymer-based OLEDs (PLEDs, also called P-OLEDs). While these OLEDs are lagging behind small-molecule OLEDs in current products (all AMOLEDs today are based on SM-OLEDs), some companies believe that PLEDs are actually the better tech for the future.

CDT's CEO, David Fyfe has agreed to answer a few questions we had on CDT's technology. David joined CDT in 2000 as Chairman and CEO. David saw CDT go public in 2004, and then negotiated the sale of CDT to Sumitomo for $285 million (in September 2007). David is also a director of Soligie, an electronics printing company, Acal Energy, a fuel cell technology developer and the Plastic Electronics Foundation.

Q: David - thanks for agreeing to do this interview. Since the Sumitomo acquisition, CDT has been rather quiet... can you give us an update on where's the company now, and where's it is headed?
Since the merger of CDT into Sumitomo Chemical in September 2007, CDT has grown substantially and received considerable capital investment to enable it to remain a leading developer of PLED technology. It works very closely with SCC laboratories in Japan and most recently has been transferring manufacturing process knowhow to SCC's own PLED manufacturing development line, recently commissioned at Ehime on Shikoku, Japan. CDT in partnership with SCC has made large strides in materials lifetimes and efficiencies. SCC prefers to take a lower profile in announcing these advances since its business model is to work with selected display maker partners in a collaborative, confidential relationship. We have also made big strides in the development of top emitting structures and in printing PLED displays. SCC's strategy is that CDT will continue to be its leading development center for PLED technology with Ehime scaling process technology to a yielding process status. CDT is also working very closely with Semprius of North Carolina, USA to develop single crystal silicon TFT structures on which PLED devices can be deposited and driven using Semprius’ proprietary stamping technology.

Q: It seems that OLED displays are finally entering the mainstream - we hear of new devices (mainly by Samsung, but also from Sony, Microsoft, LG and others) almost daily. What are your thoughts on this? what are the challenges that still exist for OLEDs?
Sony broke the logjam of resistance to the adoption of OLED in large displays by major display makers with the introduction of its XEL-1 11 OLED TV in 2007. Samsung SDI’s investment in small screen OLED production in 2007, based on LTPS backplanes was another major impetus. Since then, Chi Mei has brought on small OLED screen capacity, TMD (now wholly owned by Toshiba) has built an OLED line to manufacture small screens, LG Display will start up their Gen 3.5 line late this year and if press reports are to be believed, Toppoly will commission their capacity with Nokia as a lead customer and Panasonic have a major OLED development program for large OLED displays.