Printed Electronics Now staff06.30.20
Kopin Corporation announced its latest Lightning 2.6K x 2.6K OLED display (2560 x 2560 resolution) has now achieved breakthrough color fidelity (>115% sRGB).
This fidelity number is believed to be the world’s highest achieved on duo-stack OLED microdisplays and equal to that on the best single-stack OLED microdisplays.
This OLED display is aimed at high-performance virtual reality/augmented reality/mixed reality (VR/AR/MR) headsets.
For VR/AR/MR applications, high brightness and color fidelity are critical. One method to achieve higher brightness is using a duo-stack OLED structure.
A duo-stack OLED is two OLED structures on top of each other and connected in a series so that carriers (electrons-holes) pass through the duo-stack OLED and generate photons twice, instead of once like in the conventional single-stack OLED structure currently used in OLED microdisplays.
Furthermore, the duo stack provides more flexibility in the OLED stack design for optimum efficiency and color than the single stack, which can result in much higher efficiency (>4x), higher brightness, lower power consumption and longer lifetime.
However, previous designs with the duo-stack OLED structure introduced color mixing among subpixels, resulting in unacceptable color performance. Kopin’s patent-pending innovation incorporates a specially configured anode structure in the Si backplane to suppress the color mixing.
This ColorMax technology, believed to be applicable to all OLED microdisplays using duo-stack OLED structures, is first integrated into Kopin’s 2.6K x 2.6K OLED display which has an active image size of 1.3” in diagonal.
The display integrates high-speed D-PHY/C-PHY MIPI interface and Display Stream Compression (DSC) circuits to handle compressed video of up to 3:1 ratio. The 2.6K x 2.6K OLED display also has 10-bit color control, the world’s first in OLED microdisplays to the best of Kopin’s knowledge.
The 10-bit color control, together with the measured high color fidelity, outstanding efficiency (>6 candela/ampere), high brightness level (> 1000 nits) and high contrast ratio (>10,000: 1), now enables the much-desired studio-quality, high dynamic range (HDR) capable VR experience.
The results were obtained in close collaboration with our OLED foundry partner, Lakeside Optoelectronic Technology Co., Ltd.
Further improvements in the brightness (>2000 nits) and color fidelity are expected through the optimization of OLED deposition conditions.
By incorporating a structure to enhance the output coupling efficiency, the brightness of the OLED microdisplay could be increased to >5000 nits within a couple of years.
“In addition to the exciting development on color performance in duo-stack OLEDs, we have demonstrated the video operation of our first-generation 2.6K x 2.6K OLED display with MIPI input signals and test samples, which are available to select customers,” said Dr. Boryeu Tsaur, GM of Kopin’s OLED Display business unit. “The design of our backplane was very complex requiring the integration of many different functional blocks including digital memory. The Si backplane is in reality a complex high-performance integrated circuit, basically like having an OLED Display Driver IC (DDIC) or System on Chip incorporated into the Si backplane. Our 2.6K x 2.6K display on our ColorMax Si backplane is not only a display but is a display on-chip (DoCTM). The whole wearable monitor is now a single 1.3” chip. We plan to enhance our backplane design further to reach a 120-Hz frame rate operation with a global shutter while reducing power consumption even further in our second-generation 2.6K x 2.6K DoC. We expect to have the second generation 2.6K x 2.6K DoC ready by the end of this year and commercially available to select partners in 2021.”
“We have always had the grand vision that VR/AR/MR headsets should have an excellent experience and yet they should also be like regular eyeglasses so that more users would be willing to wear them for much longer periods of time,” added Dr. John C.C. Fan, president and CEO of Kopin Corporation. “Kopin, therefore, has pursued a holistic and ambitious approach to achieve this goal, which requires multiple breakthroughs. The glasses need a super high resolution and a great color wearable monitor integrated with all the necessary system electronics. It also needs a thin, compact Pancake optics to pair with the wearable monitor to provide studio-like immersive color video images. Now, with our new breakthrough ColorMax Si wafers, we believe we have all the necessary building blocks. We are combining all our platform technologies -- ColorMax, DoC and Pancake – and collaborating with Panasonic Corporation for a compact VR headset incorporating our second-generation 2.6K x 2.6K OLED DoC. Our disruptive dream of VR eyeglass is now almost at hand.”
