Among the next generation display technologies currently in the making, transparent technology is one of the most anticipated technologies for its vast application and versatility, in particular for its expected lifestyle-changing role in smart home solutions.
One particular example is the transparent display designed to replace a conventional refrigerator door. Just picture your refrigerator with a transparent door. Not only does it allow you to have a quick scan of what’s inside, but captured information would be shown on the display letting you know when the milk expires, what to cook with the available ingredients, or if the temperature inside the fridge is at its optimum level. All of these data would be readily available without having to open the fridge door to check.
Most importantly from the display perspective, the useful application of such revolutionary data relies on the actual visibility and desired transparency of the display. This is where LG Display has spearheaded some breakthroughs, but not without its own trial and errors.
We bring you some highlights of the initial challenges faced by our very own researchers at the S-IPS Technology Team, the special unit in charge of transparent LCD tech development at LG Display.
Chief Research Engineer, Wonho Lee: “The whole point of developing a transparent LCD is to develop so that the contents can be seen clearly. The transparent LCD shows off vivid colors and three times higher transparency level than existing clear display products. LG Display managed to overcome the difficulty of enhancing the both characteristics of color and transparency at the same time (increasing the transparency level three times higher than the existing transparent LCD). We put a team together to focus solely on transparent display back in 2012. At first, we had started off with a normal display but realized that the screen would show blurry results. We then opted for a special LCD panel that could overcome this issue.”
<Figure 1: Transparency Degeneration Effect >
When same object is observed, transparency difference occurs depending on product changes (Glass -> Panel)
Senior Research Engineer, Young-Min Jung: “To be clear, conventional LCD panels have their limitations because of their low transmittance. We can control the brightness with stronger backlight, but it then becomes less energy efficient as it consumes more electrical power. Then, there is also the option of enhancing transmittance by lowering color saturation level—we could remove the color filter or even just poke a hole into it, but then this would only result a monotone effect.”
<Figure 2: Structure of LCD>
Senior Research Engineer, Tae-Han Kim: “While black and white colors would also need to be replicated when needed, realizing colors accurately is a crucial element in transparent display technology. The main objective of our project was to enhance the transmittance by two or three times while maintaining the ratio of color reproduction.”
Realizing the Optimal Transparency
Researcher Engineer, Duk-Keun Yoo: “To put it simply, we took a two-fold approach: enhance the open ratio of TFT, and add the white elements to the RGB(Red+Green+Blue) color filter via G+ Rendering technology. In other words, we raised the transmittance by securing more space.”
<Figure 3: Penetration Ratio Enhancement through Application of G+ Technology>
<Enhancement by adding white elements by 25% to the initial RGB color filter and
enlarging transparency TFT open ratio>
Senior Research Engineer, Young-Min Jung: “So the key was to reproduce the accurate color while enhancing transmittance and this was a challenging process. The result display would either show blurriness or light refraction. Resolving this part took the longest time, as we had to accurately analyze where and how to fix in order to achieve optimal transparency.”
Research Engineer, Duk-Keun Yoo: “Actually, transparency is not just about enhancing transmittance. Equally important factor is the continuous testing done to ensure clear visibility from all angles and at every point of the display. Given that we’re exploring a new frontier, this process also required not only constant evaluation but also innovative approaches in measuring and assessing, as well as coming up with the appropriate solutions.”
The Near Future in Reality
Surely consumers will be provided with benefits and values when these technologies become commercialized. Not only will their lives become convenient, but technology applied products will act as a source of new design in homes. It is quite surprising that home appliances and cutting edge display technology are converged together to provide such a different but innovative lifestyle. LG Display reflects consumers’ needs and dreams through display and provides real added value, something more than just enhanced technology.
Chief Research Engineer, Wonho Lee: “The 55-inch transparent refrigerator will be produced around April 2014 for commercial purposes, with higher accuracy in color and transparency. The display market is expected to grow as well when the products become commercialized.