Mike Davis

In the growing field of wearable devices, one area that is seeing much interest is the category of head- mounted display (HMD), also known as near-eye display (NED). HMDs can be classified as one of two types depending on the intended use: Virtual Reality (VR) or Augmented Reality (AR). Virtual Reality replaces the wearer’s view with an immersive environment in a broad field of view, such as for gaming or personal cinema use. On the other hand, Augmented Reality types overlay a portion of the viewer’s existing field of view with a see-through image containing information supplied from an external source, such as a computer, smartphone, or a wireless connection to a cloud database. AR types can be “glanceable”, where the information is occasionally viewed in the periphery of vision, or can be displayed directly in the center of vision for critical applications like surgery or equipment repair and assembly.

In either type, a virtual 2D or 3D image is formed at a comfortable viewing distance by means of optical projection, but inevitably the image has to pass through the pupil of the human eye and focus on the retina. The eye then creates the limiting set of parameters and tradeoffs for the delivery of such an image. These tradeoffs are described in detail in our downloadable white paper DLP® Technology for Near Eye Display, and an excellent overview can be found in this EDN article entitled An insider's guide to designing near-eye displays. Those thinking about utilizing DLP technology for such applications should review our whitepaper Getting Started with TI DLP® Pico™ Technology. Also, TI evaluation modules are available and enable developers to rapidly assess DLP technology. Developers can work with one of our network of design houses that can package the technology in the kit to fit the application.

But why should you consider DLP Pico technology for HMD applications? In my examination of other technologies, I was consistently distracted by the “gray box”, especially for the see-through AR types. This undesirable artifact is caused by the background black level of the display (the area where there is no content), which in technical terms is related to the inherent contrast of the display technology used. In comparison to competing technologies, DLP technology has inherently high contrast (2000:1 full on to full off (FOFO) or more typical), which, along with advanced signal processing techniques, helps create highly transparent backgrounds for AR displays. Another critical advantage of DLP technology is high speed data processing, which produces very low image latency in applications such as video games where the image tracks the movement of the wearer (display latency as low as 8.33ms at 120hz input frame rate). Many applications are also battery operated, which benefit from the low power consumption of DLP chipsets, proprietary algorithms, and its efficient use of non-polarized LED illumination.

So, immerse yourself in our technology whitepapers and augment your thinking about head-mounted display!