Zeev's Turnips Patch-No Politics (ZEEV)

[Train Guy]

50% of the cost of a LCD TV is the back light? Could any of your ducted light technology apply to that? It appears OLED is going to be superceeded before it ever gets widespread use.

Flat panels go nanotech: Taiwan’s ITRI pioneers CNT-FED, part one
Chris Hall, DigiTimes.com, Taipei [Friday 21 January 2005]

TFT LCD looks firmly entrenched as the dominant flat-panel technology, but in fact the displays industry is keen to find a technology that delivers better performance – and, crucially, at lower cost. Alternative technologies exist, but often suffer from their own well known drawbacks. In the case of OLED technology, for example, there is the infamously short lifetime of the display.

One promising technology is the carbon-nanotube field-emission display (CNT-FED). In Taiwan, key development work on CNT-FEDs is ongoing at the Electronics Research and Service Organization of the Industrial Technology Research Institute (ERSO/ITRI). Recently, following ITRI’s announcement of the development of a 20-inch CNT backlight unit (CNT-BLU), DigiTimes.com had the opportunity to talk with Dr. CC Lee, deputy director of flat-panel development at ERSO/ITRI.

This is Part I of a three-part interview. Part II will follow on Monday, January 24. Part III will appear on January 25.

Q: What is the current status of the ERSO/ITRI CNT-FED project?

A: We started the carbon-nanotube field-emission display (CNT-FED) project about five years ago, when we began an evaluation of a CNT emitter. About five years ago we also began making carbon nanotubes (CNTs) at ITRI, and we found their properties very suitable for making FEDs. We began research for the project, and, prior to 2004, successfully completed research for both 4-inch and 10-inch CNT-FEDs. Currently we are at the stage where we have developed a prototype, a 20-inch CNT-FED backlight unit (CNT-BLU).

We are also at a stage where we need to focus on developing materials. We discovered that some materials required for successful CNT-FED and CNT-BLU development, such as the phosphors, are not available as a standard commercialized material, so we are cooperating with other branches of ITRI, such as the Materials Research Laboratory (MRL) and the Union Chemical Laboratories (UCL), who are now handling the materials development.

ERSO, meanwhile, takes care of the process and system integration. In addition, we have started to transfer technology to industry. As well, we have started to transfer system integration and process integration technology to some panel makers.

The UCL and the MRL have transferred some technology related to the materials and chemistry of CNT-FED production to the chemical industry, and also to some panel makers, so overall, the status of ITRI’s CNT-FED project is one of transfer of the technology to industry and assisting the industry with the evaluation of the commercialization of the display and also the commercialization of the backlight unit (CNT-BLU).

Q: How close are you to commercialization of CNT-FED technology?

A: We transferred the technology from ITRI to the industry about two years ago, but at that time there were still some issues with mass production. Two years later, the industry has now learned how to produce small-size CNT-FED devices, and they plan to develop products for some niche markets, such as indicator lights for cars, and also some special lighting applications, after no longer than one year.

They want to get some feedback from consumers as quickly as possible, so they thought they would start with some relatively low-end commercial products for niche markets, which would then enable them to get consumer feedback after a period of no longer than a year.

The indicator lights they want to develop are of the VFD (Vacuum Fluorescent Display) type, for use in cars and a wide range of consumer electronics items – in DVD players for example, in timers, and in outdoor information displays. This type of display can be commercialized.

Q: Could these be made cost-effectively using CNT-FED technology?

A: The answer is yes, in the case of both VFD and LED displays. Compared to the VFD type of display, the FED could be used to make a passive-matrix display. This kind of CNT-FED display can easily show graphic designs, on-screen patterning and text. But with the VFD type of display, displaying dynamic design or patterning isn’t easy. You need to have a large increase in the number of components to achieve this type of functionality.

For the LED type of display, the cost of each chip is expensive, and you have to use bonding or surface-mount technology to bond each kind of RGB LED on the substrate on the module. So the assembly cost is high. But for the CNT-FED you just need to use screen-printing, so if you want to make the RGB you just need to screen-print the R, G and B phosphors simultaneously. That’s a qualitatively different technology, and the cost of each color is lower.

As I mentioned, ERSO/ITRI has also researched another application for CNT-FED technology, a CNT backlight unit (CNT-BLU). This will be a cost-effective product that could be used as an LCD-TV backlight.

Our purpose in researching a CNT-BLU is to reduce the cost of an LCD-TV, and this is in response to the needs of the LCD-TV market. Many companies are looking for new kinds of flat-backlighting technology, and CNT-BLU technology can solve many of the problems that crop up with cold-cathode fluorescent lamp (CCFL)-based backlighting.

ERSO/ITRI has now completed evaluation of the CNT-BLU and demoed the prototype, which is based on our own patented technology. At this time, it is best for local companies to have the core technology without the need for foreign authorization, if they want to develop and produce a CNT-BLU.

Q: So CNT-FED technology could also be applied to larger displays?

A: Certainly. As I indicated, the industry is aiming to make some smaller-size displays, after a period of no longer than one year, because they want to use the process to make the small-size CNT-FEDs or CNT-BLUs. They want to follow this approach because they want to learn how to mass produce CNT-FEDs and how to increase the yield during mass production. If they get more experience in mass production, then they will transfer the technology to make larger-size CNT-FEDs. So the smaller-size display is meant to be a learning curve. It can deliver products to some niche markets, but the market size is small, and making these smaller products functions basically as an educational and training process.

The ultimate target of CNT-FED display technology is a TV application, but if you want to know how to produce a large display you have to start with a small one. In that way you can obtain a step-by-step improvement in the mass production process and the yield.

Screen-printing offers a low-cost way to fabricate the larger-size display compared to TFT LCD, so we emphasize that point – we want to make the larger size but at a relatively low cost.

Q: The ERSO/ITRI CNT-FED project is in fact just one year away from commercialization?

A: Yes. We have announced the 20-inch BLU because we want to apply the technology, in the first instance, to the TFT-LCD industry. That is our strategy for making CNT-FED technology a reality. In Taiwan, the TFT-LCD industry is already well developed; there is a large involvement in TFT-LCD panel production. But if you want TFT-LCD technology to be a viable player in the TV market, then you must resolve the cost issue of the BLU. The cost of the BLU is high because mass production of the BLU is complicated. Our initial approach is to use CNT-BLU technology to lower the cost of the backlight module for the Taiwan TFT-LCD industry, and thus lower the cost of TFT-LCD TVs.

Mass production of a CNT-BLU could also help the CRT and PDP panel makers, in the future. The first step will be to assist the TFT-LCD makers, and then CRT and PDP makers.

Q; Are you able to give any figures as to how much might be saved by using a CNT-BLU for a TFT-LCD TV?

A: Generally, for a TFT-LCD TV, the cost of the BLU is about 50%. The cost is high. Right now, using CNT-FED technology, we could reduce the cost of the BLU to around 25-30%, so the cost a TFT-LCD TV could be reduced significantly.

Another issue is repair and maintenance. Traditionally TFT-LCD production has used a CCFL for the BLU, so for a 30-inch TFT-LCD TV, you need to incorporate 16 CCFLs in the backlight unit. That requires a complicated assembly. But if one day, one of the CCFLs fails, then the complete BLU has to be replaced. To simply replace one CCFL and still maintain uniformity would be an enormous problem.

But if we use a single unit for the BLU there would be no need for any repair because if only one pixel or one line fails, you will see no difference. There would be no visible difference because we can structure the design on the cathode to eliminate the degradation of one cathode line. There would be no need to worry about the failure of each cathode line for a CNT-BLU. Considering the cost of repair, we think that that one low-cost CNT-BLU is more effective for TV applications.

Q: A CNT-FED TV would not require a backlight, so presumably it could be lighter and easier to handle than a TFT-LCD or PDP TV?

A: Generally the size and weight of the CNT-FED are similar to those of the PDP, but the thickness of the glass for CNT-FED and PDP is 2.8mm. Compared to the TFT LCD, where the glass is about 0.7mm, the weight of the CNT-FED and PDP is higher than the TFT LCD panel, but with the TFT LCD we need to add the backlight unit. So generally, the weight of the whole TV set is not so different because the BLU is heavy.

For the consumer, the weight of the CNT-FED is not the first priority, if they want to choose a display. At the larger sizes, say 30 inches or above, consumers do not usually want to carry the unit around the house.

http://www.digitimes.com/news/a20050121PR204.html