Seiko Epson Develops 500ppi 3D Display for Mobile Phones

Aug 6, 2008
Tetsuo Nozawa, Nikkei Electronics
A 3D display developed by Seiko Epson (click on the picture to make it life size). 3D images cannot be recorded by one camera in principle. So, when only one camera is used, images look two-dimensional.
A 3D display developed by Seiko Epson (click on the picture to make it life size). 3D images cannot be recorded by one camera in principle. So, when only one camera is used, images look two-dimensional.
[Click to enlarge image]
The principles of the 3D display with a "lenticular lens" (Image provided by Seiko Epson and translated by Tech-On!)
The principles of the 3D display with a "lenticular lens" (Image provided by Seiko Epson and translated by Tech-On!)
[Click to enlarge image]

Seiko Epson Corp developed a 3D display that is targeted at mobile phones and can show high-resolution 3D images visible to the naked eye with no special glasses.

Despite its small size (2.57 inch), the 3D display features a pixel count of 1024 × 768 (XGA). Seiko Epson plans to commercialize the display in two years, the company said.

"The resolution of the display is about 500ppi," said Goro Hamagishi, general manager of the Display Development Center, Corporate Research & Development Div, Seiko Epson Corp. "It is one of the world's highest resolutions of the direct-view-type displays that do not use projectors."

To display 3D images, a special lens called "lenticular lens" is placed on pixels so that different images can be seen from different angles. A lenticular lens is composed of an array of many hog-backed convex lenses, each of which is as large as a few pixels.

Several cameras are used to shoot images from slightly different angles. Then, the images are resolved into pixels and arrayed on the pixels of the display based on a certain calculation (rendering).

Because right and left eyes see the display from different angles, the images look three-dimensional. This method was established in the 19th century.

There are three main features in the 3D display. (1) 3D images are created by using up to eight cameras, and their resolution is as high as 384 × 256 pixels, equivalent to QVGA. (2) The design of the lenticular lens was reviewed to improve 3D images by adjusting the balance between the vertical and horizontal resolutions. (3) Seiko Epson considerably improved the problem that the images were distorted when a user at a certain distance watches the display while moving.

In general, the resolution of the 2D images shown by 3D displays deteriorates when the amount of information for 3D images is increased by, for example, using many cameras. It is because more pixels are used for 3D-related information. To solve this problem, Seiko Epson adopted the following measures.

As for (1), the original pixel count was drastically increased. And concerning (2), the company utilized the pixels in the direction in which human eyes are not very sensitive to resolution (vertical direction).

In regard to (3), Seiko Epson reduced by half the cycle in which images change depending on angles (viewing image width).

"So far, in our industry, it has been indisputable that 62-65mm, the distance between right and left eyes, is the best," Hamagishi said. "This time, we cut it by half to 31-32.5mm (to enhance 3D images)."