MIT engineers have developed a new way to make sharper, detect-free displays, with the invention of vertical, full-colour microscopic LEDs.
These new micro-LEDs could help in paving the way for the next generation of virtual reality displays. The limits of current LEDs are more noticeable when using hardware such as augmented reality and virtual reality as the pixel density can result in a “screen door effect” where the users perceive stripes in the space between pixels.
If you were to open up a laptop screen, you would find a plate patterned with red, green, and blue LEDs. When electrically powered these LEDs produce different colours and shades. However, the use of LEDs is reaching the limits of how small they can become while still performing well. Now, MIT engineers have developed a new way to make LEDs by stacking the diodes to create vertical multi-coloured pixels rather than in a horizontal patchwork.
Superior LEDs
Associate professor of mechanical engineering at MIT, Jeehwan Kim spoke on the new LEDs saying “This is the smallest micro-LED pixel, and the highest pixel density reported in the journals. We show that vertical pixelation is the way to go for higher-resolution displays in a smaller footprint,”
“For virtual reality, right now there is a limit to how real they can look,” adds Jiho Shin, a postdoc in Kim’s research group. “With our vertical micro-LEDs, you could have a completely immersive experience and wouldn’t be able to distinguish virtual from reality.”
Each stacked pixel can generate a full commercial range of colours and measures around 4 microns wide. The microscopic pixels or Micro-LEDs can be packed to a density of 5,000 pixels per inch.
The fabrication of micro-LEDs requires extreme accuracy as the microscopic pixels of red, green, and blue need to be grown separately on wafers. These are precisely placed on a plate in alignment with each other to properly reflect and produce various colours and shades. Kim commented that “This pick-and-place fabrication is very likely to misalign pixels on a very small scale. If you have a misalignment, you have to throw that material away, otherwise, it could ruin a display.”
Streamlined process
The team at MIT has been able to come up with a potentially less wasteful way to fabricate these micro-LEDs. This also doesn’t require as much precise pixel-by-pixel alignment. The new vertical LED approach is entirely different compared to the conventional horizontal method.
“In conventional displays, each R, G, and B pixel is arranged laterally. Which limits how small you can create each pixel. Because we are stacking all three pixels vertically, in theory, we could reduce the pixel area by a third” comments Shin.
The team fabricated a vertical LED pixel as a demonstration, which showed that by altering the voltage to each of the pixel’s red, green, and blue membranes, they could produce various colours in just a single pixel. The team has plans to improve the operation of the vertical pixels and work toward making an array of vertical micro-LED pixels
Paige Cook is a writer with a multi-media background. She has experience covering video games and technology and also has freelance experience in video editing, graphic design, and photography. Paige is a massive fan of the movie industry and loves a good TV show, if she is not watching something interesting then she's probably playing video games or buried in a good book. Her latest addiction is virtual photography and currently spends far too much time taking pretty pictures in games rather than actually finishing them.
