A different view

2 mins read

High quality 3d displays are set to appear in portable devices.

In less than two years, 3d tv has moved from being a discussion topic to a technology beginning to appear in people's living rooms. When you add this to the phenomenal interest in 3d movies, as evidenced by Avatar, it's no surprise to discover that work is now underway to bring 3d to other consumer electronics products – including the mobile phone and other portable devices such as gaming. But you may be surprised to discover that attempts were made almost 10 years ago to create 3d displays for mobile phones. Those attempts failed for a number of reasons. Lee Spencer from the European Design Centre within Sharp Laboratories of Europe said those reasons included poor image quality, low brightness and resolution and the thickness of the display. Certainly, module size will be critical to the success of any 3d enabled phone. Spencer expanded on the theme, suggesting that key contributors will be 'cool' handsets and, importantly, wide availability of 3d compatible software and components. He said successful 3d handsets will need: * the ability to switch between 2d and 3d, with the same image quality in both modes * high 3d picture quality, regardless of orientation, and * a thin profile. Sharp is addressing these issues and believes its parallax barrier technology meets these points, with the benefit that no changes would be needed to a device's hardware system design. Sharp has further developed parallax barrier technology and has now incorporated it into a 3.4 inch full wide vga tft lcd which supports 16:9 format images. The concept behind parallax barrier is simple; it guides light from the backlight to either the left or the right eye. Two stereoscopic images are displayed in altering pixel columns, creating a sense of depth. Because the parallax barrier is created by controlling liquid crystal molecules, the orientation of the 3d images can be changed readily between portrait and landscape. The barrier can also be switched off, allowing 2d images to be displayed at the screen's full resolution. Even in 3D mode, the screen has a pixel density of up to 165pixel/in; half of the 2D operation. Nevertheless, Sharp says this is sufficient to support clear images, particularly when the screen's brightness of 500cd/m² is factored in. Module thickness is said to be similar to that of as conventional 2d displays, even though a touch screen facility is included. Sharp's other 3d technology is Dual Depth. The approach allows two different images to be displayed in distinct depth planes, but within one display module. While parallax barrier technology is seen to be better suited to hand portable applications, dual depth technology is more likely to find application in larger scale products, with automotive displays a major target. Dual depth works by creating partial reflections within a dual depth display module and by including polarisation optics. Two light paths are created. In the first path, light is not deflected and the image is perceived as coming directly from the lcd panel. However, light from the second path is reflected back into the module by the polarisation optics, then reflected out again by the partial reflectors. This second image is perceived as originating from beneath the lcd. The depth perceived by the viewer is related directly to the actual depth of the display module, as well as to the distance between the polarisation optics and the partial reflector and to the refractive index of the display medium. Conventional images can be displayed by switching off the reflecting elements. A possible automotive application is instrument clusters, where a second image plane could be used to display warning signs. However, Sharp points out that the dual depth approach does have an effect on image brightness, as well as viewing angle.