3D Display System

Displays used in mobile phones, handheld games, and other mobile devices have shown remarkable progress as resolution has become sharper and clearer with each passing year. Now another breakthrough is stirring interest and excitement - the emergence of three-dimensional displays. Adding considerable new value to images and video, NTT DOCOMO has developed a portable 3D display system that enables viewers to view 3D images from any direction without having to wear those cumbersome glasses.

Traditional 3D display systems are based on the principle of stereoscopy, whereby the 3D effect derives from the difference between the images registered by the left and right eye as the result of their horizontal separation, a phenomenon known as binocular disparity. This type of 3D display has been incorporated into a host of products but is far from ideal because it usually requires viewers to wear special glasses to enjoy the 3D effect or, if 3D glasses are dispensed with, limits observation of the 3D effect to a very narrow range. The 3D display developed by NTT DOCOMO overcomes these shortcomings. Although we continue to rely on the principle of stereoscopy, we have adopted a new approach - known as high-density directional images display - that endows the object with very smooth and natural appearing motion as the observer's position changes (motion parallax) without the need for 3D glasses.

High-density directional images displays employ a large number of directional images - projections of a display target - with each image projected from a slightly different angle. As the viewer moves around the static display, the transition from one image to the next is so smooth and imperceptible that the viewer has the illusion of moving around a 3D object. Our most recently developed display allows objects to shift dynamically to match the viewing angle of the observer, and 3D action can be observed over a significant range (within a 60-degree horizontal angle and 30-degree vertical angle). A built-in camera senses the position of the viewer (the angle from which the viewer is observing the display), and automatically adjusts to that viewing angle in real time to maintain the 3D effect.

The 3D display is a high-definition liquid-crystal display to which a lenticular sheet has been attached, the latter essentially being a ribbed panel consisting of dozens of optical-grade cylindrical lenses arrayed in parallel vertical lines. The cylindrical lenses exhibit the 3D effect when viewed from a horizontal perspective, and diffuse light in the manner of ordinary glass when viewed from a vertical perspective.

In the case of ordinary 2D images, each point on the surface of a displayed object is represented by a single luminance value (pixel) in a one-to-one relationship, and viewers see exactly the same pixel regardless of the angle from which they are viewing the display. 3D images are fundamentally different from 2D images in that they have several subpixels. A cluster of multiple subpixels is known as a 3D pixel, and the lenticular sheet is attached to the display in such a way that each cylindrical lens overlaps several subpixels, each of which is emitting light in a different horizontal direction.

We think NTT DOCOMO's 3D display system has enormous potential. Objects have such a convincingly three-dimensional appearance that you want to reach out and touch them. We envision all sorts of imaginative applications for this technology to mobile phones including realistic games where the characters and images are rendered in 3D or mobile Internet shopping that allows customers to view potential purchases from virtually any direction.