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The WAVE Report
Issue #0901------------------1/5/09 |
The WAVE Report archive is available on http://www.wave-report.com
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0901.1 Technology Directions in LCD
0901.1.1 Samsung
0901.1.2 Chi Mei Optoelectronics (CMO)
0901.2 Energy Star Impacts Televisions
0901.3 Flexible Displays
0901.3.1 ITRI
0901.3.2 Flexible Display Center (FDC), Arizona State University
0901.3.3 LG Display
0901.4 Strides Made In Organic Electronics
0901.5 Optically Addressable LCD
0901.6 WAVE Assessment
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0901 IDRC 2008
By John Latta
Orlando, FL
November 4-6, 2008
This is the 28th SID conference on Display Research. Most of the papers given were on LCD, flexible and OLED displays. The presenters are dominated by companies and universities in Asia – which is where the action is. There are about 150 in attendance. The conference is being hosted by the University of Central Florida, The Center for Research and Education in Optics and Lasers. Overall the quality of the papers was high and many had spirited discussions.
0901.1 Technology Directions in LCD
Both Samsung and Chi Mei gave similar talks on the directions that LCD technology will take in the next several years. These were not about future products but the underlying technology which will go into them.
0901.1.1 Samsung
The talk was given by Sang Soo Kim, SVP Samsung Electronics.
The theme was stressed, which has been reported on before, that all display technology will eventually gravitate to TFT-LCD. Its technical advantages over other display technologies span:
Wide color gamut,
Low power consumption,
High performance in bright ambient lights and
High resolution.
Because research into these areas has allowed TFT-LCD to make continual advances this is the only technology which can cover the range from 1” to 100” screen size.
The market expansion in TFT-LCD has happened in 3 waves:
1st Wave – 2001 – LCD technology is used in 100% of notebooks
2nd Wave – 2005 – LCD technology takes 72% share in monitors
3rd Wave – 2008 – LCD technology has 55% of the television market
Even the forecasters have been wrong. In 2005 DisplaySearch predicted the LCD market to be $85B while it grew to $100B. The LCD-TV market was also predicted, for these same years, to be $28B but in fact it was $41B.
It is predicted by DisplaySearch that the LCD-TV market will be 250m units by 2012, in 2008 it was already 120m units.
The progress over 10 years has been “massive” in the words of the speaker.
1998 2008
Brightness 200cd/ sq m 1,500 cd/ sq m
Contrast Ratio 150:1 1m : 1
Response time 55ms 5ms
Viewing Angle 90 deg 180 deg
Color Gamut 45% 150% NTSC
Color Depth 6 bits 10bit
Resolution XGA, HD FHD, UD
Likewise the form factor has changed significantly:
TV CRT LCD (coming)
Picture Quality SD FHD
Depth 56cm <10mm
Weight 50Kg 9Kg
Power 200W 90W
MPRT 5ms <5ms
Samsung has developed the S-PVA technology which will enable 5000:1 contrast ratios in televisions in the market in 2009. This is achieved with a new polarizer film and a new C/F resin.
With the emphasis on energy efficiency Samsung will be using 3 technologies to reduce the power consumption.
Higher Transmittance with an advanced panel design
Active Backlight Dimming including LED local dimming
High efficient optical components supported by a new diffusing plate and high efficient lamp/LED.
The goal is to drive the power for the LCD module to 120W for 52” and <70W for 40”.
Significant progress is being made in “ultra-slim” LCD televisions. In 2008 Samsung showed a prototype of a 7.9mm 40” panel which also has 5000:1 contrast ratio. The key to the thin designs is backlighting with side lit LED illumination.
Motion blur is a major issue with LCD-TV because it is a Hold-type display rather than an Impulsive-type display with a CRT Phosphor. The first step to eliminate this issue was with 120Hz interpolated frames. But achieve a smooth image requires that the interpolation go to 240Hz.
There is a continuing drive to achieve UD displays which are 4K X 2K and 60” in diagonal. Samsung has shown a 82” 120Hzx UD LCD display in 2008.
The requirements for the next generation LCD-TV include:
Convergence with the PC
Realistic displays – as if you are there
Design – slim and light
Intelligent – interactive and multiple functions
To achieve a realistic display will require the following in the 2010 to 2012 time frame.
Mainstream TV size – 60”
Resolution – UD (4K X 2K)
Frame Rate – 240Hz
Contrast Ratio – 10,000 : 1
To be intelligence means that the future TV will support 2 way communications, it will be a digital hub and a multipurpose display.
The design element requires that the television be able to hung on the wall and supported by wireless communications – there is no wire to implement the display – only power.
In the video show of a future display, this included access to YouTube and the ability to communicate via the display, i.e., telepresence like.
Samsung’s fab strategy was stated that they will skip 8G and 10G fab and go directly to 11G. This implies glass substrates of 3,000mm X 3,320mm. From this it will be possible to make 6 displays of 72” diagonal.
A new complex will be built at Crystal Valley in Korea. This will encompass 2.1M sq m.
0901.1.2 Chi Mei Optoelectronics (CMO)
Chung-Kuang Wei gave the presentation.
A major direction to the improvement of LCD panels is reduction of the thickness. CMO has the following in its product line in 2008.
NB panel, 13.3” – 1mm thick
Monitor 19” – 2.5mm thick
LCD TV 40” – 8mm thick
OLED TV 27” – 10mm (not implied a product)
The key to depth reduction is the back light. CMO uses a slim side lit LED back light with light guides. This back light structure is 9.9mm.
An ultra slim notebook panel is only 1.2mm based on a glass thickness of only 1.2mm. The panel is as thin as a CD.
A monitor panel at 19” with WXGA is 3.3mm thick and has output of 300 nits.
Using this technology CMO has made a double sided display which is only 7.3mm thick. It is 19” and supports WXGA (1440 X 900) and weights only 1172g.
CMO is doing the following to increase the contrast ratio of LCD panels:
High Contrast resist
Improved PVA material
Improved Compensation film
Improved PSA material
Surface treatment of the polarizer
Dynamic backlight
Local dimming backlight
To lower the power CMO is applying the following:
Increasing backlight efficiency by using more LEDs at lower driving current.
High transmittance cell design
High efficiency backlight film
The response time of the LCD panel is focused to improve to 3ms with 240Hz processing and LED scan backlight. It is projected that 3ms response will be reached by 2008.
In terms of display quality, CMO feels that human visual acuity will play an increasing role in the size of displays and the resolution. This is driven by the need to maintain the same visual experience no matter how close or large the display is. Another factor is the emergence of auto stereoscopic displays. With Hollywood making the transition to 3D, the creation of depth perception comes directly at the expense of horizontal resolution. If the same visual quality is to be preserved with a 3D display, this implies the resolution increase. CMO gave the following examples.
30 deg field of view
Distance from the display 3X picture height
2D baseline resolution – 1920 X 1080
4 view 3D with same resolution – 3840 X 2160
16 view 3D with same resolution – 7680 X 4320
The other example cited which will drive display resolution up is public displays. Shown was a 103” display in a public venue. If the public uses this, it will be close up, much like CityWall. In this case the resolution could rise to 7680 X 4320 in the examples given by CMO.
0901.2 Energy Star Impacts Televisions
Larry Weber described in detail the efforts to create an international standard to measure television power. This is already impacting the designs of LCD-TFT televisions, as outlined by CMO and Samsung. Key points made in this talk include:
A study done by the CEA, in 2007, showed that the power consumption of analog televisions was the highest of all consumer electronics at 53TWh, 53B kwh, with PC’s second at 21 TWh. Consumption for year 2006. This is 1.4% of all the energy consumption in the US and 36% of all US residential CE energy consumption.
The reality is that it is expected that digital televisions will consume even more power. A 42” flat panel television will take 250 watts, a 2X increase, over analog.
Thus, there is considerable pressure by environmentalists and government regulators to manage this source of energy usage. A key factor is to have Energy Star applicable before the digital television transition.
A major issue is:
How to measure the energy consumption of a television?
This is a more difficult problem than one might expect. Thus, the effort to create and agreed to an international standard to define and measure energy consumption of consumer televisions. Larry Weber was on the IEC committee which developed the standard. He gave a compelling talk./
One of the most important issues is to define what is being displayed and this will help set the power level. Currently in Japan the concept of Average Picture Level (APL) is used. An all white screen is an APL level of 100% while a black screen is 0%. There are well known relationships between the power used in a television and APL. But this is not enough, processing in the television set can change the APL and thus distort the ability of a direct measurement of the video input signal to predict power consumption.
What the committee did was to develop a series of video segments which represent average television programming content. This is a simulation of the APL of a program. Significant effort went into the preparation of the content to reflect the average and thus a benchmark by which all televisions, irrespective of technology, could be measured.
The IEC, International Electrotechnical Commission, was the forum for the development of the standard which uses defined television content as the means to measure power consumption. The value of this standard, IEC 62087, is that it results in one number in watts, it is easy and quick to measure and fair to all display technologies.
The standard comes with a video disk(s) which support HD and SD.
The government response to the standard was swift. The EPA via Energy Star adopted it immediately. Specific Energy Star limits have been set. Other countries are in the process of adopting the standard.
An excellent effort.
0901.3 Flexible Displays
Three presentations were given on flexible displays. In sum, they amount to important incremental progress in this emerging class of displays.
0901.3.1 ITRI
John Chen, VP & GM, Display Technology Center, ITRI (Taiwan) outlined the efforts in his center to study, design and fabricate flexible displays.
ITRI was founded in 1973 to develop a technology base in Taiwan. It currently has 5791 employees of which 4,917 are in R&D and 1,019 with Ph.D.’s. The Display Technology Center (DTC) is one of 5 focus centers within ITRI. The lab at DTC is a Gen 2 facility which supports substrates to 370 X 470mm. It is one of the few open fab facilities. Companies can come to use this lab for a fee to test technology and fabrication methods. Recently added were 2 R2R processes: Screen Printer and a Laser Etcher.
The benefits of a flexible display are:
Slim and light
Easy to carry
Large area and
Energy Saving
It is estimated that the market for flexible displays, as per iSupply, at $283m in 2010 and growing rapidly to $1.198B by 2012.
ITRI has built the following flexible displays:
Monochrome Flexible ChLCD
3.5” X 4.5”, 30 dpi, CR 6
Long Display Flexible display
10cm X 330cm
Single Layer Color ChLCD
10.4” QVGA
40 ppi
Color – 4 bits
Passive matrix driving
The road map for developments shows R2R color Ch-LCD by 2010.
Applications being targeted include:
e-reader
e-badge
e-poster
e-wallpaper
0901.3.2 Flexible Display Center (FDC), Arizona State University
The FDC has been in operation for 5 years and built an impressive strategic partner list. The primary support comes from the US Army. There are partnerships with companies and universities in: Materials, R&D, Systems Integrators, Toolsets for Manufacturing, Manufacturers and Display Technology. Companies include LG Display, e ink, HP, Honeywell and many others. The FDC also has a professional staff which carry out research and run the facility. It also has a Gen 2 pilot fab line.
FDC is focused on addressing manufacturing challenges in 3 areas:
Robust materials on manufacturable processes on flexible backplanes;
Manufacturable high quality TFTs within substrate constraints.
Manufacturing ready substrates.
The manufacturing protocol FDC is focusing on is Bond – Debond and is working with its partners to develop the materials.
The technology demonstrations which FDC has shown include:
3.8” QVGA EPD on PEN (Plastic)
3.8” QVGA EPD on Stainless Steel (SS)
210 ppi display on SS which can be scaled to VGA on a 3.8” display
Efforts are continuing with OLED. It has shown:
64 X 64 UDC PHOLED on PEN
13.4” OLED – currently in production
OLED remains an area of significant challenge for high quality and flexible displays.
0901.3.3 LG Display
Kyoung Mook Lee presented recent work on a 12.1” flexible a-Si:H TFT LCD on a plastic substrate.
The requirements for a flexible display include:
Thin
Light weight
Conformal/Flexible/Rollable
Non-rectangular and curve shapes
Interactive – touch input
Ubiquitous
Plastic as the substrate layer has the following attributes:
Advantages
Transparent
Light
Rollable
Rugged
Disadvantages
Poor Thermal stability
Permeability
LG has developed a multi-barrier structure to reduce surface roughness of the plastic and to protect the structure from chemical damage.
The TFT process is done at 150 deg C.
The panels which LG has built has
Mobility of .4 sq cm/Vs
Threshold Voltage - .3V
Current On/Off Ratio – 10**6
LG has fabricated a 12.1” SVGA display at 83ppi with a 52% aperture ratio.
In summary, this work has shown that the low temperature process has good dimensional stability, optimization of the stress of the plastic substrates, good device performance and minimization of the misalignment between the TFT and CFA.
LG believes that TFT-LCD is a strong candidate for future flexible displays.
0901.4 Strides Made In Organic Electronics
The prospect of integrated circuits made with printing presses is based on soluble organic electronics. Considerable progress has been made in transistors with mobility sufficient to create circuits with 1000’s of transistors. One of the first applications could be RFID tags which require circuits at the cost of pennies. According to the speakers today these can be as short as 2 years away.
University of Texas – A. Dodabalapur
A theme of the talk is that channel conductivity is more important in optimizing organic transistor performance than electron mobility. At the same time improving channel speed can be accomplished by reducing channel length. A figure of merit has been developed for channel conductivity. Turn on time for FET was shown from 500ns to as low as 100ns. It was stated that the research has shown that drift mobility is comparable to field-effect mobility and that OFETs are well behaved in terms of transient response.
University of Korea – Yongtaek Hong
Many applications were cited for flexible and large area electronics. These include sensors, energy harvesting, displays, lighting and flexible circuits. The research has developed methods of making silver electrodes with ink-jet printing. These have good conductivity and surface properties. All-solution processed OTFT have been fabricated which has good mobility and ohmic-like behavior without current crowding. Building on this work the University of Korea is developing large area flexible sensor arrays. The can be used on the body and form an electronic skin. Sensing could include: touch, pressure, temperature, chemical and biological.
University of Illinois – Qing Cao
This work is focused on using carbon nanotubes as the semiconductor material in flexible electronics. It is claimed that Carbon Nanotubes offer mobility of 1,000 and similar to GaAs. Single-Walled Carbon Nanotubes (SWNTs) offer mobility to 10,000 sq cm/Vs. and an off ratio of 10**6. A medium scale IC which implements a 4 bit decoder has been developed. The challenge of carbon nanotube thin films is electronic uniformity while an inorganic semiconductor ribbon remains expensive.
0901.5 Optically Addressable LCD
National Sun Yat-Sen University, Taiwan – Tsung-Hsien Lin
An optically addressable display is one that can be written with light in the surface of the display. Applications cited include: electronic price tags, smart cards, digital time piece, wearable displays and signage. The advantage of an optically addressable display is that no electronics is required, it is bistagle and there is no backlight necessary. Such a display can be flexible, durable and robust. One of the drawbacks of the technology is long writing times – 1+ minutes The addressing can be done with an LED.
0901.6 WAVE Assessment
IDRC provided a very good snap shot of the state of display technology. The important points to glean from the presentations include.
TFT LCD Technology continues on a path to dominate the FPD market as the technology further matures. One result is that significant efforts are being spent on incremental improvements which make it very difficult for any display technology to compete – even OLED. At IDRC the following developments were discussed: thin displays, low power, larger areas, 240Hz refresh rates, high contrast ratio and wide color gamut. Multiple examples were shown in presentations of displays which incorporate these technologies. It only reinforces the strong and long term market position held by TFT LCD.
Flexible Displays is the next display frontier. Displays which conform to a surface have many applications. Already there is a flexible display in a cell phone. These displays make it possible to integrate displays with the design of products in a way not possible before. But significant challenges lie ahead to me displays at low cost and which are durable.
A number of papers were presented on developments in organic electronics – circuits which can be printed just like words on paper. An example of 4 bit decoder was shown to illustrate the current state of the technology. However, what needed to galvanize the market is a large volume application. The RFID tag was cited as one such application however any mass market deployment is several years away.
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