Despite financial setbacks, the LCD industry continues to innovate.
by Alfred Poor
FROM ovens to cars, from mobile phones to tablet computers, from dynamic store signage to high-definition televisions, the dominant information-display technology clearly continues to be liquid crystal. Display Week 2012 reflected the leading role of LCDs in the industry; from the 10 sessions in the symposium (more than any other track) to the exhibit hall, the technology was visible at every turn.
Traveling a Bumpy Road
Participants of this mature technology are not coasting along on autopilot; they face some daunting challenges. One of the most significant was presented from the start at the Business Conference hosted by IMS Research the day before the exhibition opened. Several speakers made reference to the fact that LCD suppliers on the whole have lost money for the prior consecutive seven quarters. Stiff competition has forced them to find ways to reduce material and production costs; profit margins have been difficult to maintain.
The industry is also facing competition from new technologies on a scale that has not been seen since flat panels started to replace CRTs in many applications. OLEDs are clearly a major challenger; two 55-in. HDTV demonstrations in the exhibit hall drew admiring crowds throughout the week, and OLED technology already has made significant inroads in the mobile-device market. Various forms of bistable displays are succeeding through e-Readers and other applications.
Even the success of LCD technology has created challenges for the industry. For the first time ever, the LCD-TV market declined in the first part of 2012, as penetration rates in North America and Western Europe are around 90% (as reported by IHS). This has resulted in questions about how to make the best use of the production capacity already in place.
The LCD industry is not just sitting back as a spectator and watching all this develop. Researchers and manufacturers are pushing hard to advance the technology to lower costs even further and to improve performance. For example, the symposium had three separate sessions devoted solely to the discussion of blue-phase liquid crystals (BPLCs), including a paper from Hui Chuan Cheng et al. from the University of Central Florida about a polymer- stabilized BPLC that uses vertical field switch-ing and an oblique path for the backlight.
Will Rust Replace Sand?
Another hot topic was about the use of metal oxides instead of silicon as the semiconductor backplane for LCD panels. Some of this research has been driven by the fact that OLEDs need better electron mobility in their backplanes, but a rising tide raises all boats and the benefits can also help LCDs.
At present, more than 95% of LCDs use amorphous silicon (a-Si) for their backplanes. While this is good enough for most applications, the drive for higher pixel densities has increased the use of laser-annealed polysilicon (poly-Si) backplanes. There are limits to the size of the panels that can undergo laser annealing efficiently, and this resulted in a search for alternatives. A leading alternative is the use of metal oxides, and IGZO (In:Ga:Zn oxide) is one of the most popular choices at this point.
At Display Week, Sharp and Semiconductor Energy Laboratory announced that they have used IGZO to create mobile LCD panels with a resolution of 500 pixels per inch (ppi). Sharp Microelectronics of the Americas (SMA) also introduced a 31.5-in.-diagonal LCD with QFHD resolution (3840 x 2160 pixels), which is equivalent to four 1080p displays (Fig. 1).
Fig. 1: Sharp demonstrated a 32-in. LCD that uses IGZO for its semiconductor backplane. One measure of the metal-oxide capabilities is that this panel has QHD resolution (3840 x 2160 pixels). Photo courtesy the author.
LCDs have also moved away from cold-cathode fluorescent lamps (CCFLs) for backlights and most are now using solid-state LEDs as a light source. Expense and color performance are two of the challenges presented by LED backlights, and a new joint effort by 3M and Nanosys has provided an alternative. Nanosys's Quantum-Dot Enhanced Film (QDEF) can transform blue light into precise frequencies of red or green light. When stimulated by a blue light source, the film emits white light suitable for an LCD backlight. 3M provides a polymer/inorganic barrier film to shield the QDEF from damaging oxidation.
By adding this film to an LCD panel, manufacturers can switch from expensive white LEDs to blue LEDs. This also eliminates the problem of "binning" the white LEDs to get the desired color temperature, an elimination that may result in a cost reduction of 25–50% in the cost of the LEDs, according to a 3M representative. The Nanosys QDEF was the recipient of SID's Display Component of the Year Gold Award.
The Large and the Small of It
Among the large LCDs in evidence at Display Week, one of the most impressive was a 55-in. QFHD LCD that is also an autostereoscopic 3-D display (no glasses required) from AU Optronics Corp. This unit is commercially available, and it won SID's Display of the Year Gold Award.
Sharp also announced an impressive 80-in. LCD panel to go along with its 60- and 70-in. models, all intended for digital-signage applications. (After all, what fun is it having a Gen 10 LCD fab if it is not going to be used to make really big panels?)
At the other end of the logarithmic scale, one could also see some tiny LCD panels. For example, Kopin Corp. showed a full-color VGA LCD (640 x 480 pixels) that was a mere 0.21 in. on the diagonal (Fig. 2).
Fig. 2: Kopin's VGA microdisplay is just 0.21 in. on the diagonal and is designed for near-to-eye applications such as viewfinders. Photo courtesy the author.
The company also showed a WQVGA (480 x 240 pixels) designed for "information snacking" applications such as augmented reality. The device can produce images with a luminance of 1000 cd/m2 while consuming less than 150 mW of power. In the same booth, Forth Dimension Displays showed a new QXGA (2048 x 1536 pixel) liquid-crystal–on–silicon (LCoS) microdisplay. Lumus was also showing an LCOS panel with 720p resolution on a 0.38-in.-diagonal display intended for near-to-eye applications, such as head-mounted displays embedded in eyeglasses. The see-through image would make it well-suited for augmented-reality systems such as the Google Project Glass.
Taking "small" in another direction, LG Display demonstrated a 4.5-in. LCD panel that was a mere 0.99 mm thick. The company's Ultra Slim technology reduces the backlight-unit thickness to just over half the normal dimension. When paired with thinner glass, the LCD panel could easily be mistaken for an OLED panel if just taking the thickness of the panel into consideration.
An LCD for Every Purpose
Between these extremes, one could find just about anything else one might want in a display at the exhibition. Two of the industry leaders had a large presence in the hall. LG had a variety of panels on display, including a 55-in. model with a bezel width of only 5.3 mm between tiled panels (Fig. 3). These tiles support stereoscopic 3-D with passive glasses, making it practical to create large 3-D video walls.
Fig. 3: LG Display showed a video wall using nine 55-in. 3-D LCD panels that are separated by only 5.3 mm, the combined width of their thin bezels. Photo courtesy the author.
Samsung showed a 13.3-in. panel (1366 x 768 pixels) that was only 2.85 mm thick, available now as a high-definition display for ultrabook computers (Fig. 4).
Fig. 4: Samsung's 13.3-in. WXGA notebook panel is claimed to be the thinnest LCD notebook panel on the market. Photo courtesy the author.
The recently created Kaohsiung Opto-Electronics (KOE), formerly Hitachi Displays, was showing in-plane-switching (IPS) panels in conjunction with Ocular LCD's touch-panel technology. Chimei Innolux Corp. (CMI) demonstrated its MQ technology that reduces motion blur in mobile-device displays by using a combination of overdrive and a flashing backlight. Tianma Microelectronics was another LCD manufacturer that showed a variety of LCD-panel products in its booth including a 4.5-in. LCD for mobile devices that uses NLT's Super-Fine TFT (SFT) technology to obtain QHD (960 x 540 pixel) resolution on the small panel.
Kyocera (formerly Optrex) demonstrated a wide range of LCD panels intended for automotive and industrial applications, including a 2.5-in. round display and panels using its Omni Directional View (ODV) technology that improves viewing angles. Renesas/NLT Technologies showed a 21.3-in. 5.8-Mpixel monochrome LCD designed for medical-imaging applications and a 9-in. color 1080p panel suitable for automotive entertainment.
Several exhibitors, including Kristel Displays and LiteMax, were showing high-brightness LCD panels for a range of applications. And if one could not find an LCD panel size needed for a specific application, Tannas Electronics Display was on hand showing its custom panel-cutting technology that can provide just about any dimension that might be required.
Sailing through the Storm
The LCD industry may be navigating some stormy fiscal seas at the moment, but it remains the pre-eminent technology for displays of all sorts. Expect to see LCD panels get thinner and lighter, which is likely to yield benefits to mobile devices such as smart phones, tablets, and ultrabook computers. If IGZO is the success that the manufacturers hope it will be, we could see resolutions increase and production costs fall even further. These and other improvements may help LCD hold off the growing attack by OLEDs for market dominance. And if Display Week 2012 is any measure of the future for these versatile flat panels, it appears that research is ready to help manufacturers advance to the next level and compete with new technologies as they come along. •