Microdisplays and Sensors

Within SMWA-funded project BACKPLANE we have researched high-resolution OLED microdisplays at 0.18“ screen diagonale and shown a prototype at pixel size of 2.5 µm and pixel density of 10,000 dpi – world-record!

The continuous microdisplay improvements in recent years have been driven by various requirements such as pixel density, energy efficiency, color, brightness, or frame rate. We have developed a wide range of microdisplays in full-color or monochrome, from ultra-low power versions to high-resolution variants for the use in augmented- (AR) and virtual-reality (VR) applications and other wearables.

The majority of microdisplays on the market are currently developed and manufactured on 200 mm wafers in 250 nm to 90 nm CMOS process nodes. The manufacturing of microdisplays on 300 mm wafers has been rare so far. 

However, market requirements for image quality, pixel density and integrated functionality are continuously increasing. Therefore, Fraunhofer researchers have been examining the scaling effects in smaller CMOS technologies and investigating the use of 300 mm backplane processes as part of the "Backplane" project funded by the SMWA. In this context, the researchers have now succeeded in making the next major leap forward in development: For the first time, they realized an OLED microdisplay with tiny 2.5 µm pixels (corresponding to 10,000 dpi) at a display diagonal of 0.18 inch. This demonstrated the feasibility of developing displays based on 28 nm small-node technology on 300 mm wafers and realized the world's smallest pixels of an OLED microdisplay.

The newly developed OLED microdisplays have a resolution of 1440 × 1080 pixels in monochrome or 720 × 540 pixels in full color. On the one hand, the flexible display architecture allows the refresh rate to be reduced to 0 Hz in extreme cases when the display content remains unchanged, thus avoiding all unnecessary data transfer - an enormous advantage for power consumption. Conventional displays require a minimum refresh rate here, regardless of content. On the other hand, the new microdisplay also allows frame rates of up to 480 Hz in extreme cases – internally even up to several kHz. 

Depending on the design, the new displays can be used in lifestyle products such as sports glasses or as head-mounted displays in motorcycle helmets, in industrial scenarios for wearables in logistics or for remote maintenance solutions. The now even smaller dimensions pave the way for even more ergonomic systems.