Mobile Auto-stereoscopic Displays
Mobile 3D displays are designed to fulfil specific requirements. They should be sufficiently small and thin for a handheld device and should provide autostereoscopy – the ability to create 3D effect without requiring glasses. Furthermore, backwards compatibility is a desirable feature – the possibility to switch the display back to “2D” mode, when 3D content is not available. Presently, there are several announced products or prototypes of reconfigurable 3D displays.
A display produced by Sharp uses electronically switchable reconfigurable parallax barrier display based on a patterned retardation film. When the “3D mode” is on, the light passing through the subpixels is selectively blocked, in order different subsets of the screen image to be seen with each eye. These subsets form the “left” and “right” views, respectively. This display has been used to produce the Sharp AL3DU laptops (discontinued). The same parallax barrier has been used for a prototype of portable MVC decoder and player, developed by Nokia Research Center.
A reconfigurable 2D/3D technology from Ocuity Ltd. uses a Polarisation Activated Microlens array. The microlens array is made from a birefringent material such that at the surface of the lens there is a refractive index step for only one of the polarisations. A switchable polariser selects either the unrefracted light for 2D displays (i.e. the cylindrical microlens array has no impact) or the refracted light.
A display family announced by NEC provides 2D compatibility by using Horizontally Double-Density Pixels (HDDP) configuration and fixed lenticular lenses. The HDDP configuration is composed of the RGB color arrangement in horizontal stripes with the pixels doubling the horizontal resolution. When the display is to be used in 2D mode, the same image data is written in the two adjacent pixels. With this approach, the 2D/3D switching can be done entirely by software means, and different parts of the displays can be in different modes.
Newsight has been marketing 3D displays based on wavelength-selective optical filters and with sizes ranging from 8.4’’ to 54’’. They claim their technology allows also manufacturing portable displays of size of 2’’ or so.
A single user 3D display technology developed by SeeFront utilizes lenticular optical layer mounted in front of a LCD panel. A camera tracks the positions of the eyes so to guide a software module which adaptively fractionizes the stereoscopic views. The optical system can meet design requirements for various size displays including portable displays with small viewing distance. Only 3D viewing mode is provided.
Beside the above reviewed display solutions, auto-stereoscopic displays based either on lenticular optics or parallax barrier technology have been marketed by a number of companies.
Source: Mobile 3DTV Blog
