50 Years of LCD Technology

50 Years of LCD Technology 50 Years of LCD Technology


A Display Week 2018 Celebration

by Stephen Atwood

Suppose you could go back in time and speak to the early pioneers of computing technology. Who would you pick and what would you ask them? Would you start with Charles Babbage and ask him how he was able to visualize all the intricate parts of his Analytical Engine? Or would you drop in on Alan Turing and ask him, well, anything really. Just listening to him talk would have probably been an amazing experience. You might ask William Shockley whether he anticipated that his point-contact transistor would eventually give birth to the entire modern electronics age, or maybe you would just book an afternoon with Robert Noyce and talk about the evolution of integrated circuits. Whatever you decided to do, you would do it because you would be seeking a first-hand appreciation of the vision that drove those great pioneers to their achievements.

Of course, we can’t actually travel back in time to meet the early pioneers of computing, but at the most recent Display Week 2018, we had the rare privilege of doing something very similar – meeting some of the pioneers and founding figures of the liquid-crystal display industry. At a special afternoon session and reception created to celebrate the 50th anniversary of LCD technology, we heard how LCDs were invart8ented from the inventors themselves.

As we learned from Larry Weber’s excellent article, “David Sarnoff, Display Industry Visionary,” in the last issue of Information Display, the genesis for the development of LCDs came in significant part from a challenge that Sarnoff himself gave his technical staff at RCA – to develop a technology for making large-size televisions. This led at first to promising work on electroluminescent materials by Jan Rajchman, who patented the idea of a large, flat-screen, active-matrix TV. Various methods of light modulation were explored, including the idea of using electric fields to stimulate liquid crystals to selectively transmit or disperse light.

This research continued through the 1960s, until in 1969, Wolfgang Helfrich, a physicist working at RCA, conceived of a new type of LCD using the nematic phase that we now know as the twisted-nematic (TN) LCD. This approach required that the liquid crystal be placed between two polarizers. The device switched polarized light by changing its molecular alignment in response to an applied electric field. This remains the fundamental principle of operation for all LCDs today. Which brings us to Martin Schadt, the first speaker at the event, who spoke passionately about the exciting discoveries that came together to make the first TN LCDs a reality, including the rubbing effect and the first commercial room-temperature nematic liquid-crystal mixture. Helfrich eventually left RCA and joined Schadt at Hoffmann-LaRoche in Basel, Switzerland, where in the fall of 1970 they developed the first TN-mode LCD prototype.

As Hoffmann-LaRoche was underway commercializing TN LCDs, other researchers, like Fang-Chen Luo and Peter Brody, were developing active-matrix addressing, showing the first 6 x 6-in. prototype at Westinghouse. Luo, who also participated in the event, spoke rather humbly about his work and that of his colleagues, but painted a broad landscape of the technology development that occurred between the work in 1974 and the first 102-in. TFT LCD TV that appeared in 2006.

Inventor Terry Scheffer walked us down the path of continuing developments in LC technology, with the creation of super-twisted-nematic (STN) liquid crystals, and InJae Chung (LG) and Jun Souk (Samsung) each recalled their experiences in overcoming numerous technical challenges to adapt the technology into commercially viable large-size TVs.

Along the way, and over the course of the afternoon, we heard detailed accounts of many other critical achievements, such as the creation of a-Si and poly-Si TFTs, the “one-drop fill” that reduced the time to fill a panel from hours to minutes, overdrive technology to improve response time for high-quality moving images, several new LC modes to enable wide viewing angles, and countless manufacturing process developments, all from the people who were there to create and lead them.

Fang-Chen Luo (left) and Martin Schadt (right) were among the LCD pioneers who spoke at the 50th Anniversary LCD Event at Display Week 2018 in Los Angeles.

So how big a deal is this technology, really? Let me help you appreciate the magnitude. Tell me how you would finish this sentence: “Liquid-crystal display technology is…”

Amazing. OK, easy answer. Can you be more specific?

Great for TVs, phones, tablets, computer displays, etc. Sure is! And just about every other application you can name as well. During the opening comments for the session, SID President Helge Seetzen commented that LCD technology has paved the way for the ubiquitous penetration of displays into virtually every possible application. Today most of us have LCDs in our cars; we wear them on our wrists (or more commonly, in our pockets and purses); all our new appliances have them; and they’ve been to outer space on the space shuttle. They are virtually everywhere.

Complicated. Sure is. Over the past 50 years, dozens of different fields of science and technology had to converge to create what we have today. While most other innovations are built on previous foundations, LCDs are somewhat unique in that developers had to for the most part build their own foundations as the technology evolved from inventor George Heilmeier’s first demonstrations of the electro-optic effect of dynamic-scattering liquid crystals at RCA in 1968. Key areas such as semiconductor physics, material science, fluid mechanics, optics and electro-optics, and lots of chemistry have been called upon to get where we are today.

Rocket science. No, maybe not quite that complicated, but let’s come back to that.

Resilient. For sure! Over the last 50 years, countless development efforts have evolved the technology from its simple roots in passive-matrix monochrome TN-mode text displays. During the 1970s and 80s, critical advancements such as rubbing to establish alignment, passive- and active-matrix addressing to control pixel arrays, and STN and dual-domain modes all helped improve viewing angles and contrast to a point where the technology really began to show promise. Along the way, amorphous-silicon and poly-silicon technologies were also developed to support the practical fabrication of thin-film transistors (TFTs) for active-matrix switching. By the 1990s, LCDs were starting to find practical applications in places such as avionics, and eventually they became a critical component in the evolution of laptop computers. But there were still many performance limitations to overcome, including response time, color gamut, and viewing angle.

While LCDs performed well and were crucial to laptops, CRTs were well established as the performance standard for televisions, and a lot more development was needed to make large-screen LCDs that could compete. In the next decade, numerous innovations such as overdrive, faster switching and higher frame rates, additional LCD modes such as vertical alignment (VA) and in-plane switching (IPS), copper electrodes, dual-side drive, and many more all converged to displace CRTs, and achieve never-before-seen television screen sizes. Along the way came the iPhone and the enabling of a whole new class of consumer devices built around the LCD screen. At each milestone, a new threshold of performance was exceeded, and the industry continues to evolve today with quantum-dot backlights, glass-based light guides, 4K and 8K resolutions, stereoscopy, and many more innovations that were on display at Display Week’s exhibition.

Based on vegetables. Huh? OK, well that’s actually true – carrots, specifically. While LCD technology is now 50 years old, the first discovery of the materials now classified as “liquid crystals” dates back 130 years to 1888, when scientists first identified a compound extracted from carrots that exhibited physical properties not yet seen. Among the strange properties were the existence of two melting points, the reflection of circularly polarized light, and the ability to rotate the polarization direction of light. Austrian botanical physiologist Friedrich Reinitzer observed that cholesteryl benzoate melted at 145.5 °C (293.9 °F) into a cloudy liquid, and at 178.5 °C (353.3 °F) it melted again, and the cloudy liquid became clear. Merck first started offering liquid-crystal materials for scientific study at the turn of the 20th century but it wasn’t until the 1960s that scientists started looking at LCs for display-type applications.

Unlikely. Maybe. Consider what might have happened if the early pioneers of LCD technology had foreseen all the development work that lay ahead, and the problems that had to be solved from 1968 to today. Would they have taken it on? Of course they would have! As I listened during the presentations from pioneers including not only Schadt, Luo, Chung, Scheffer, and Souk, but also Koji Suzuki, Kenji Okaoto, Mark Verrall, and William Doane, I could still hear the passion in their voices and the love of the challenge that they had taken part in. However, I wonder what their business leaders might have said if they had all sat down in one room around 1990 and assessed what was ahead of them:

•  Investments measured in the tens of billions of dollars to develop the technical and manufacturing infrastructure needed for today’s commercial successes.
•  A market place that almost immediately oscillated between over- and under-supply and invoked commodity-style pricing pressures.
•  Products with unique capabilities but limited exclusivity to key markets.
•  Consistent and relentless competitive pressure at every turn.

Would those leaders have decided to move forward? Certainly several early entrants did not choose to do so, and others took up the challenge anew along the way and became dominant players. Congratulations and much respect goes to those who did recognize the possibilities of this technology and fought hard for it with vision and courage.

Unstoppable. It sure seems that way! Many competing technologies have been developed to displace LCDs in major applications. Through the ears we’ve heard the phrase “LCD killer technology” many times – at least a couple of times each decade while I have been in this industry. Some, like plasma TV, have had commercial successes, and other more recent contenders, including organic LED, are gaining a foothold, but nothing seems poised to make a sizable impact on the world domination of LCDs.

There seems to be an almost cosmic serendipity surrounding LCDs and their supporting science. A few years back we considered the unique threat that was coming from OLEDs and their much wider color gamuts, incredibly thin form factors, and potential for very high resolutions. At that same time, along came quantum-dot technology, more new LC modes, and also oxide TFTs to battle back each of these performance threats. Suddenly LCDs could achieve 4K and even 8K resolutions (and very high pixel densities) with extremely wide color gamuts and much higher refresh rates. The large-screen HDTV beachhead that OLEDs were poised to take reverted back to LCDs once again.

So is it rocket science? Well, in some ways it certainly feels like it. While LCDs are not literally as complicated as a space craft, their development has employed what might be a similar order of magnitude of engineers and scientists, and probably crosses the boundary to almost as many science and technology disciplines. LCDs have clearly occupied a similar timespan in human history as modern space programs. They have traveled beyond Earth’s atmosphere and might even be on other planets someday soon. Those who contributed to the fundamental sciences used in this field can be uniquely proud that their work lives on and enables such a broad swath of products, applications, and economic activity around the world.

And, on a selfish note, I just want to say what a privilege it was to hear these great technology leaders talk so passionately about their work. Congratulations to Chair Shin-Tson Wu and the entire committee from SID for this special, well-organized program at Display Week 2018.  •


Stephen Atwood is the executive editor of

Information Display

. He can be reached at satwood@atwoodracing.com.