Toshiba Mobile Display Co Ltd (TMD) exhibited three types of three-dimensional (3D) displays at SID Display Week 2009, an academic conference that runs from May 31 to June 5, 2009, in Texas, the US.
One of them is based on the "integral imaging system," which utilizes a lens array to allow viewers to see 3D images with the naked eye. This display has been presented by TMD at a number of exhibitions in various locations.
The remaining two types were exhibited for the first time, according to TMD. They are (1) the "Time Sequential Autostereoscopic 3D OCB Display," which provides the same level of resolution even if it is viewed with the naked eye and (2) the "Crosstalk-free 3D Display," which is viewed using glasses equipped with liquid crystal shutters.
The two 3D displays are based on the OCB (optically compensated bend) technology developed by TMD. This technology is intended for small LCD panels that feature a moving picture response time (MPRT) as short as 3ms.
In addition to the OCB technology, TMD realized stereoscopic viewing with the naked eye for the 3D display described in item (1) by applying a special film manufactured by 3M Co of the US to the inner surface of its panel. This special film functions to send images to the left and right eyes at different angles.
With this method, the "effective resolution" of 3D images normally decreases to about half the resolution of the panel. But TMD divided the backlight LEDs into right and left parts and mounted one on either side of the panel so that the LEDs light up alternately via a light guide plate. As a result, the images for the right eye and those for the left eye are displayed in turn, preventing the deterioration of the resolution.
This is not a completely new method and was applied to some products in Japan in the past. However, "there were some issues including the slow response time of liquid crystals," said Yasuhiro Takagi, a professor of Tokyo University of Agriculture and Technology.
This time, TMD operates the LCD panel at 120Hz, allotting 60Hz each for the left and right images. The company took advantage of the fast response speed realized by the OCB technology.
The 3D display described in item (2) is a combination of an LCD panel that is operated at 120Hz and glasses equipped with liquid crystal shutters. Images for the right eye and those for the left eye are displayed alternately in the same way as the display indicated in item (1), but this display does not have a special film and the images for both eyes are displayed at the same angle.
Instead of the film, it uses liquid crystal shutters on the glasses, which open and close to switch the images sent to the left eye and the right eye.