Wearable computing devices must be small, lightweight, and energy efficient in order to be successful. When it comes to displaying information, the Google Glass is a prime example of what a head-mounted display can be. The lynchpin in such a design is the imager: a tiny screen with sufficient resolution to deliver useful information to the wearer. At the recent SID Display Week 2014 in San Diego, Sony demonstrated some new OLED microdisplays and published the results of their research in a paper: “A 0.23-in. High-Resolution OLED Microdisplay for Wearable Displays .”
Attention focused on the smallest of the three displays: a 0.23-inch OLED panel with 640 by 400 pixels. (This is a 16:10 wide-screen format with resolution slightly lower than a standard VGA computer monitor.) It is a “color by white” design using a white OLED backplane with color filters to create the red, green, and blue sub-pixels required for a full color display. This approach has the advantage of avoiding the problems caused by the faster aging of blue OLED emissive materials compared with the red and green materials.
The most important feature of these new panels is that they are incredibly energy efficient. An LCD requires that a backlight be on all the time, but OLEDs only consume power when a pixel is turned on. Sony has increased the light emission efficiency of their panels so that they require lower voltages than traditional OLED microdisplays. According to Sony, the 0.23-inch panel draws a mere 80 mW of power, which in turn reduces the size of the battery required to support its operation.
Sony also showed a 0.39-inch OLED panel with 1028 by 768 pixels (XGA) resolution that draws only 180 mW, and a 0.5 inch Full HD (1920 by 1080 pixels) resolution that draws just 390 mW.
These new panels can give wearable tech designers more choices for creating head-mounted displays for their systems.