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The WAVE Report
Issue #0712------------------9/12/07 |
The WAVE Report archive is available on http://www.wave-report.com
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0712.1.1 CDT Describes Total Matrix Addressing (TMA)
0712.1.2 Display Search View of the Market
0712.1.3 Applied Materials Predicts 2 -3 More Generations of
0712.1.4 Fraunhofer Institute for Photonic Microsystems describes Impressive Handheld Projector
0712.1.5 Sony Describes Technologies for 27” OLED Televisions
0712.1.6 Consumer Projectors
0712.1.7 Samsung Hybrid Touch Screen Panel
0712.1.8 LED Backlighting for LCD Televisions
0712.1.9 e-paper Makes Progress
0712.1.10 Electrowetting Displays
0712.1.11 Novel Technology
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0712.1 SID 2007
By John Latta
Long Beach, CA
May 22 – 25, 2006
SID is the premier event in the display industry. The combination of a growing and robust exhibition and a rich technical conference makes for the best gathering of professionals and the display of technology.
0712.1.1 CDT Describes Total Matrix Addressing (TMA)
OLED has a driving problem. In active matrix displays LTPS has the advantage of high current and stability but the down side of low yield and non-uniformity. While a-Si is a mature technology in TFT LCD panels it suffers from poor current in large panels and low lifetimes. PM is a mature technology but due to high current is limited to small panels.
In LCD displays Multi-Line Addressing is used to drive from 4, 8 or 16 lines. Unfortunately this technology works by adding and subtracting from the displayed signal, while in OLED it must only be additive. MLA would work by driving lines with common information simultaneously. This results in two problems to accomplish TMA: how to drive multiple lines of a PMOLED display and how to process an image required to drive the display. CDT claims that its technology will drive all the rows of an OLED display simultaneously.
The key to the effectiveness of TMA is the ability to craft a mathematical method that is computationally efficient to drive multiple rows and columns simultaneously. The algorithm is called Non-negative Matrix Factorization. The problem is that this takes iterations to realize an image. The number of iterations can run from 250 to 1000 as the error count decreases. CDT has developed an algorithm which is much more efficient. Images were shown of a “Full TMA” implementation that is suitable for TV applications.
The major advantage of TMA is the reduction of power required by the panel. It was claimed that:
2.8” QVGA OLED Single Scan = 2W
2.8” QVGA OLED Dual Scan = 1W
2.8” QVGA TMA = 450mW
2.8” QVGA AM – 350mW
A demo system is projected to be available in Q3 2007 and a TMA chipset in samples in A1 2008.
0712.1.2 DisplaySearch View of the Market
DisplaySearch has been predicting major changes in the supply of flat panels. This is happening as supply growth continues to improve but at the same time the demand is falling with the meeting of market expectations for FPD televisions.
The FPD market is $83.7B but the growth is slowing down from 47% in 2003 to only 11% in 2006. The fastest growing applications are Televisions with 63% and public displays with 60%. The growth in notebook PCs in terms of display panels is -1%. This results in the FP display industry being dependent on the TV market for growth.
OLED technology continues to generate a lot of interest but it has only 1% of the market. The revenues for OLED were down 3% in 2006 despite a 29% growth in units. The reason being pricing pressures from LCD panels. Optotech and Ness have exited the market and AUO discontinued pilot line operations. The industry key Samsung AMOLED production has been delayed by 2 quarters.
Major technical developments in displays include:
Advanced PDP Development Center Corp. has a 10 lumen/watt PDP. This is expected to significantly lower costs. However, the cell structure must change and the realization of these panels is likely 2 years away.
Organic transistor flexible displays are becoming more robust, thinner, lighter and more cost effective. Production lines are being built by Polymer Vision and Plastic Logic.
There are new developments in TFT backplane technology. One that stands out is the SiOG by Corning. This enables smaller transistors, greater uniformity and improved yield.
There were price increases in April due to the inability of panel suppliers to meet OEM demand.
1080p displays are driving the large screen display market. Consumers will pay more for what they consider a future proof display. The price premium is up to $500. It is expected that 62% of the 40” and above volume in 2010 will be for 1080p displays.
0712.1.3 Applied Materials Predicts 2 -3 More Generations of LCD Fab
ID Kang, VP General Manager, AKT Display Business Group, Applied Materials examined the direction of LCD fab generations.
Panel costs are being driven by material costs – now some 77%.
The fab equipment is massive. A Gen 8.5 fab ships in 28 crates, requires 14 truckloads and 3 747-400 freighters to move.
It is estimated that FAB evolution will go on for 2 – 3 more generations.
0712.1.4 Fraunhofer Institute for Photonic Microsystems describes Impressive Handheld Projector
In a paper entitled: MOEMS Laser Projector for Handheld Devices featuring Motion Compensation a projector suitable for a cell phone was discussed. The key is the integration of internal sensors that allow for the compensation of hand movements. This allows for a stable wall display. The compensation is for both tilt and movement. A laser light source was used but the shortcoming is that green could not be accomplished and was done in the demo with a doubled NIR source. A device was fabricated which is 240 X 240 and monochrome. It was stated that the concept has been demonstrated of the key technologies.
0712.1.5 Sony Describes Technologies for 27” OLED Televisions
At CES Sony showed both a 11” and 27” televisions based on OLED. Here at SID they described how the 27” display was developed.
In order to realize the Si film on the backplane, a laser annealing process was used with a CW laser.
This is called dLTA (diode Laser Thermal Anneal) and involves the scanning of the laser over the substrate. This process provides for high mobility which is between that of a-Si and LTPS - approximately 3 cm2/v s.
0712.1.6 Consumer Projectors
The key issue in implementing consumer projectors is the light source. There are many solutions based on the application. This is an active area and one that could hold considerable consumer promise.
Corning
Corning is developing a green laser in a small and power efficient module for cell phone projectors. This laser is frequency doubled from a 1060nm laser. They are seeking to enable cell phones to be portable display devices. This is consistent with the presentation yesterday by the Fraunhofer Institute for Photonic Microsystems. The market premise is that there should be no correlation between the device size and the image that it generates. In order to be power efficient the light sources must be laser. But as Corning said, long lived green laser diodes have never been produced.
The applications of tiny consumer projectors was the most interesting and included:
Sharing of pictures, video and content
Heads up displays
Gaming
Input and Output
Multi-user combinationsCorning stated that one could implement the equivalent of a mouse-pointing device using the combination of a projector and camera in a cell phone. Individuals could also use multiple cell phones to show different images on a surface – “multi-sharing.” It is interesting how projectors are have social implications and this is consistent with other presentations.
LEDs as Projector Light Source
VUB, a university in Brussels, Belgium, described how LED could be used as the light source. A projector light source was fabricated. LEDs have the major disadvantage of limited light output and low efficiency. The device fabricated used the OSRAM OSTAR projection LEDs. 4 dye colors were used and now up to 6 dyes can be supported. In addition, 2 LEDs per color were used and in order to provide color and brightness uniformity a lens array integrator was used. The projector can generate 88lm output.
Wavien – Reusing Light to Increase Efficiency
The non-coherent light from LEDs results in angular diversity of the emitted light rays. This results in lower efficiency and Wavien has developed a light recycling system to improve the efficiency. Claimed efficiency increase was 40%. Several novel packaging schemes were shown that implemented these with the LED’s. An approach was also shown which supported color mixing.
Philips – Ujoy
Philips focused on the market for personal projectors as separable units. The intent is to create bright images on a surface, such as a wall. Market research indicates that an output of 200 – 300 lm is required. For battery operation this implies no more that 50W of power. Philips used a UHP arc lamp and built a new product for the application. A new casing was also developed to allow for consumer removal. Philips showed a number of design examples to illustrate how creative ID could be used to enhance the image of this product with consumers. A comparison was done with other lamp technologies including LED and laser. It was admitted that the by 2010 both of these light sources would provide illumination which is competitive with Ujoy. At the same time Philips feels that the time for the personal projector market is now and their product is positioned for helping establish the market. It was stated that this technology allows a projector to be priced at <$500 but in response to a question the price point which would significantly enable the market is $100.
Luxim – LIFI
Using a novel approach this lamp is powered by RF and has no electrodes. It is based on a quartz lamp embedded in a metallized dielectric resonator. The high Q cavity provides the basis for lamp ignition. Up to 170 W can be provided to the lamp from the RF electronics unit. At this power level the lamp outputs 13,000 lm with a 31% efficiency. Full brightness is achieved in 6 seconds.
0712.1.7 Samsung Hybrid Touch Screen Panel
Joohyung Lee, MD Development Team, Samsung Electronics described a capacitive touch implementation which overcomes many of the implantations of conventional touch panels. It is claimed that the luminance drop is only 10% to 15% and this technology will work in high light level outdoor environments. The capacitive sensor is built into the LCD panel itself. It was implied that this technology could support multi-touch and the speaker stated they have gotten requests for this.
Toshiba Matsushita Display Technology – Embedded Touch Panels with Displays
Takashi Nakamura, of the R&D Center of Toshiba Matsushita Display Technology presented a touch panel design that has an optical sensor integrated into the LTPS panel design. The optical sensors are formed on the glass substrate. The display backlight is used to illuminate the touch actions on the surface of the display. This is effectively an imager of touch actions on the surface of the display.
0712.1.8 LED Backlighting for LCD Televisions
In the market war for dominance of television flat panels it is competition between LCD TFTs and PDPs. With PDPs being an emissive display there are advantages in color gamut and frequency response for video display. From a color gamut standpoint increasingly the industry is relying on LED backlights. Two papers highlighted different approaches to this technology.
Sony
In a standing room only presentation, Koichiro Kakinuma, Sony, described the implementation they used to accomplish backlight in the BRAVIA 70in display introduced in February 2007. A key objective is to display colors that were described as “out-scaled” sRGB. Examples show included colorful nature objects such as butterflies and fabrics. Using LED backlight Sony was able to achieve 105% of the NTSC space while conventional CCFL accomplished only 71%. Sony was able to achieve excellent uniformity. An LED control system was used to stabilize the color temperature. Further, a heat pipe was used to manage the heat generated by the LEDs. It was claimed that since the first Sony product with LED backlighting was introduced the light efficiency has doubled.
3M
3M described another evolution of its LED efficiency film, called LEF-D, to increase the performance of LED backlights. In addition, a new version of its backlight specular reflector was described. The combination of these two technologies would allow a reduction of the number of LEDs by 10% and this could save from $30 - $40 in the panel costs. 3M stated that the largest barrier to broad adoption of LED backlighting is the cost of the LEDs.
0712.1.9 e-paper Makes Progress
Many presentations outlined a number of advances in e-paper technology, including the prospect of showing video.
e-paper on a Roll
zdb – Going on the Shelves
zbd in the UK has been developing and running trials on electronic point of purchase (epop) displays. Its product is called a zenithal bistable display. The attributes of the display include:
Image on with no power
Passive matrix
Image not destroyed when the panel pressed
No image deterioration over time
Uses TN construction
Readily manufacturedThe liquid crystal is aligned with a homeotropic grating. The imaging mechanism is based on flexo-electricity in liquid crystals. The panel properties include:
320 X 240 @ 100dpi
Addressing voltage = 20v
Frame time – 250 ms
Peak contrast > 15:1
Viewing angle 160 degrees
Operating range = -20 deg C to 65 deg CThere could be 100’s if not thousands of these displays in a retail store. These are updated with bounce, an electronic RF interface with the epop displays. The bounce system has a range of 200m and can support >1000 epop displays. The plan is to integrate bounce within the retail infrastructure including product sale and product pricing so that shelf labels can be automatically updated.
The company has followed this timeline:
First epaper epop displays manufactured – 2005
Retailer pilot tests in the EU – 2006
Full-scale manufacturing – Q2 2006
Commercial roll out - 2007
Nemoptic
This is a LC bistable display technology that is always on, has resolution greater than 200 dpi and uses traditional LCD manufacturing methods. The displays are capable of 32 grey levels, can support up to 32k colors and be placed on flexible substrates. Recent advancements have allowed for materials to have the following properties:
Contrast ratio > 10:1
Partial image refreshing
100 dpi colot
Up to 14” in diagonal
Panel thickness as low as .4mm
Flexible substrate implementation
Volume manufacturing and shipmentsFirst prototypes have been made of color panels. These have the following characteristics.
5.1” diagonal
QSVGA
100ppi
12:1 contrast ratio
Color saturation 7% NTSC
Number of colors 16
Sony
It was another standing room crowd to hear about Sony’s efforts to improve on its e-book display technology. The target of the work is to make the display look like a magazine one holds in ones hands. The specifications include:
Reflectivity > 60%
Contrast ratio >10
Switching Voltagbe <5v
Compatible with LCD TFT
Response time < 100ms
Flexible and with ColorSony uses a Dichroic PDLC material. Sony has spent considerable effort countering the metallic glare caused by the diffuse reflector. This glare detracts from the paper like appearance. The technique used to address this issue is to add a rear-diffusing layer.
Visual examples indicate considerable improvement.
HP
HP in its Bristol, UK laboratories focused its work on making epaper supportive of video. It was able to show:
An electrophoretic display capable of passive matrix addressing
Switching speeds capable of supporting video
Memory that lasted 3 years
Fabrication compatible with LCD technology
Sharp
Eliminated the polarizer and created a unique retro-reflector to improve performance. This reflector is similar to a corner cube whose pitch is 30nm and spans the size of the display – 3.8” Sharp stated it achieved this with good uniformity. The resulting panel had the following properties.
Panel TFT a-Si
Size – 3.8” diagonal
QVGA
RGB strip
Aperture ratio = 80%
Color 15:1 contrast ratioAt a 60Hz driving frequency and 256 grey levels the color panel consumed only 32mW. At 6 Hz this dropped to 1.2mW.
Sharp is bullish on the ability to create electronic paper capable of supporting video.
Bridgestone
Bridgestone addressed the issues of creating panel drives on a flexible panel and mating the connector to the panel. They call their panel techonogy – QR-LPD – Quick Response Liquid Power Display. The intent is to have a .2ms response time and paper like appearance. The study examined how to place the LSI drive on the flexible substrate. Bridgestone developed a bonding technique that could be used at <150 deg C on PET. This allowed the circuits to be placed on the substrate without destroying the substrate.
Siemens
Rather than use LC technology Siemens has chosen to use ElectroChromic materials. In order to make a flexible display this required the development of a new electrochromic material formulation. A key issue is lifetime and Siemens was able to show 5m cycles. The properties of the display include:
25:1 contrast
180 deg viewing angle
1.2 to 3 volt supply voltage
<100 μW/ cm*cm power
0712.1.10 Electrowetting Displays
adt group
Based on the principle of moving droplets in and out of the display pixel adt is able to achieve a high aperture ratio in a color display. The contrast ratio is 10:1 and full color displays are possible. A key factor is the ability to operate over a temperature range of -45 deg C to +100 deg C. It is claimed that video displays are possible. Given the nature of the display technology very large displays can be created. More details on the display technology will be available on the company we site in a week.
This technology is in early stages and will be several years before being commercially available.
Liquavista
Liquavista also uses electrowetting. It was proud to show watches which use its technology. These are monochrome. Production is to begin at the end of 2007. Panels up to 6”, VGA and full color are to be demonstrated by 2H 2007. It is expected that mass production of these advanced displays will happen in 2H 2008. A major advantage of the display is low power – 20% to 30% of LCD. It is capable of switching at 10ms. Note that the technique used by Liquavista displaces the liquid materials within the pixel compared to adt group that moves tbe material under the cell. As a result adt claims a higher aperture ratio.
Nano projector from explay
explay was showing a hand sized projector attached to an iPod showing video - QVGA. This is called the oio. The video was being projected onto the wall. The display uses lasers for red and green while blue is with an LED. There is a LiIon battery in the unit and playtime is expected to be 2 hours. explay will bring this product to market with partners and this is expected in 2008.
We found the image quality poor with a blue bias. Not sure why, in its present form, this is compelling – another device to carry, expensive battery, set up required to view and poor quality.
0712.1.11 Novel Technology
Liquid Crystal for Lenses
Hongwen Ren of the College of Optics and Photonics, University of Central Florida presented an interesting use of liquid crystal (LC) materials. This includes:
Fabrication of LC microlens arrays;
Glass shell LC lens; and
Variable focus lens.The microlens arrays can be used to create autostereoscopic 3D imaging systems. The variable focus lens was suggested for use as the lens in cell phone cameras. The focal length of this lens can be varied from 8mm to .5mm with an aperture of 15mm.
Blue Phase LC Display
Kyushu University of Japan, by Hirotsugu Kikuchi, presented a means to use the Blue Phases of LC materials in displays. A blue phase is described below:
Liquid crystal 'blue phases' are highly fluid self-assembled three-dimensional cubic defect structures that exist over narrow temperature ranges in highly chiral liquid crystals. The characteristic period of these defects is of the order of the wavelength of visible light, and they give rise to vivid specular reflections2 that are controllable with external fields. Blue phases may be considered as examples of tuneable photonic crystals with many potential applications. The disadvantage of these materials, as predicted theoretically and proved experimentally, is that they have limited thermal stability: they exist over a small temperature range (0.5–2 °C) between isotropic and chiral nematic (N*) thermotropic phases, which limits their practical applicability.
The project which is seeking to use blue phases is a JST – Japan Science & Technology Agency) effort to create advanced liquid crystal display materials.
The target of the project is the creation of materials that are Isotropic, fast (<ms) and do not require any surface treatment. Central to this presentation is the use of a chiral dopant to improve the properties. The voltage transmission curve showed excellent properties in going from transmission to 100% transmission. However, the voltage range to accomplish this was from 40 to 100v. In summary, it was claimed these materials have large potential for display applications but the high voltages required need to be addressed in additional work.
University of Rochester on Cholesteric LC Flakes
K. L. Marshall of the University of Rochester, Laboratory for Laser Energetics, described efforts to create color LCDs using flakes. As background:
The motion of highly dielectric polymer cholesteric liquid crystal (PCLC) flakes suspended in a host fluid can be controlled with an ac electric field. The electric field acts to induce a dipole moment on the flake due to interfacial, or Maxwell-Wagner, polarization. Theoretical modeling of PCLC flakes as oblate spheroids shows that the flakes will reorient to align one of the two major axes parallel to the electric field. A PCLC flake's orientation determines its ability to reflect light of a specific wavelength and circular polarization. The ability to switch the position of PCLC flakes with an electric field has implications for electro-optic devices and display applications.
This work supported the following:
Flakes can be created with standard off the shelf materials.
Response times are in 10s ms and the drive voltages are in the mv.
Changing the PCLC material composition can vary the optical properties widely
By changing the dopants it is possible to create new switching modes and highly saturated colors.
By microencapsulating in flexible binders it is possible to create flexible displays with these properties
Much research remains to be done to realize the full potential of PCLC flakes.
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