Kopin Microdisplay Targets High-Brightness AR Applications

Kopin Corporation, said to be the largest U.S. developer of display systems for wearable technologies and military applications, announced on September 11th a new generation of liquid crystal displays (LCDs). These microdisplays incorporate advanced designs and processing techniques aimed at significantly increasing performance over prior generations. The new Brillian product line incorporates an advanced pixel structure, newly formulated liquid crystal materials and enhanced manufacturing processes to produce good image performance in applications requiring extreme high brightness. The very high brightness of this transmissive LCD allows it to target see-through augmented reality (AR) applications where the display must compete with high ambient light. (Note: there is no relationship between this new product line and the LCoS and RPTV manufacturer Brillian Corporation that became Syntax-Brillian in 2005 and went bankrupt in 2009. MB)

Kopin says the Brillian displays with the advanced pixel structure have more than double the contrast ratio of conventional displays. Full-color Brillian displays exhibit contrast ratios higher than 500:1 and brightness levels greater than 34,000 cd/m² (10,000 foot-lamberts) when coupled with an appropriate illuminator. The illuminator would normally be supplied by Kopin’s customer, not Kopin. With the use of the newly formulated liquid crystal materials, switching time has been reduced by about 30% to a fraction of one frame time to eliminate any perceived symbology latency.

Kopin’s High-Performance SXGA Brillian microdisplay is intended for AR applications (Image Credit: Kopin Corporation)

I got in touch with Dr. Hong Choi, Chief Technology Officer at Kopin, and he provided me with some additional details on the device. He said that, currently, the Brillian family has only one member but additional family members are planned. This first family member is an SXGA (1280 x 1024) device with a 0.97” (24.6mm) diagonal size and a pixel pitch of 5 µm x RGB x 15 µm. The full-color device uses color filter array (CFA) technology with RGB color stripes. Dr. Choi expects that the device would typically be used at 60Hz but says it is capable of a frame rate of 90 Hz maximum.

Kopin President and Chief Executive Officer Dr. John C. C. Fan said:

“The Brillian LCD is the result of a multi-year development effort to satisfy the increasing performance requirements of our customers. The Brillian product line offers the extreme brightness levels only possible with an LCD, while at the same time substantially boosting image contrast and lowering switching time. This breakthrough in performance will enable the further advancement and fielding of augmented reality products throughout the growing markets that we serve.”

Bill Maffucci, the company’s VP and General Manager of Government and Industrial Products added:

“This new line of LCDs is ideally suited for very high brightness augmented reality applications such as visor projected pilot displays, integrated rifle scopes, soldier tactical displays, embedded training systems and outdoor maintenance displays. The Brillian LCD microdisplays far exceed emissive devices in brightness, operating life and reliability which allows them to provide easy to read display information together with a clear view of the external scene under all lighting conditions from total darkness to bright sunlight.”

As a comparison, CFA color-by-white OLED microdisplays from eMagin are typically under 800 cd/m². eMagin claims only 4,000 cd/m² (5,000 cd/m² in its SID 2017 paper) for its emissive direct-patterned RGB OLED, although a green-only version for the same microdisplay was said to produce 60,000 cd/m². To the best of my knowledge, this is the brightest emissive microdisplay available, although it is probable that a micro-LED display will eventually exceed these values. On the other hand, if Kopin removed the CFA, the Brillian display would probably produce over 100,000 cd/m² monochrome white output and probably more with a green-only illuminator. Extreme high brightness is needed for see-through AR applications not only because of the need for the AR image to visible against the ambient light but also because of the relatively low efficiency of many see-through AR optical designs.

Nanojet Process to be Used to Make Displays

The Brillian displays will be manufactured by Kopin’s proprietary NanoJet process at its Westborough Massachusetts facility. The NanoJet process releases tiny drops of liquid crystal material with great precision (variation within a few nanograms) and provides for a purer, better controlled and very uniform layering of the liquid crystal material in the fabrication of displays, resulting in superior image quality and higher brightness. The cell gap uniformity is also said to be substantially improved to about 90% from about 70% for the conventional method. The more uniform cell gap produces more consistent contrast ratio and viewing angle performance across the display area.

In the 2015 announcement of the NanoJet process, Dr. Fan said,

“The patent-pending Nanojet process developed at Kopin is optimized for microdisplays with tiny pixels required for augmented reality (AR) and virtual reality (VR) applications. This process improves the display performance and reduces the cost to manufacture the display. The Nanojet process can be used in the manufacture of both our transmissive Cyberdisplay and reflective LCOS displays.”

Samples of the Brillian display are available for select customers now and production is expected to commence in the second quarter of 2018. –Matthew Brennesholtz