Sharp Unveils Details of its New 3D LCD Display

Sharp Corp announced April 2, 2010, that it has developed a touch-sensitive LCD display with which 3D images can be seen with the naked eye. The display is aimed at mobile devices, such as mobile phones, smart phones and portable game consoles, that are equipped with a 3- to 5-inch display. The company plans to start shipping the touch-insensitive version of the 3D display in volume within the first half of 2010.

In Sharp's small- and medium-size LCD display business, the ratio of 3D displays will be 10 to 20% in fiscal 2010 and 50% in and after fiscal 2011, the company said.

"In the future, we would like to replace all of our existing small- and medium-size 2D LCD displays with 3D displays," said Yoshisuke Hasegawa, general manager of Sharp's LCD business.

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Reentering Market with Parallax Barrier Method
In the front part of the newly-developed 3D display, there is a panel that has a parallax barrier (a slit that partially blocks light) so that the display can show different images to the right and left eyes. The panel with the parallax barrier creates slits by controlling liquid crystal molecules. Therefore, when light is not being blocked, it can show 2D images.

The number of viewpoints is one. And the most appropriate distance to watch the display is about 30cm (right in front of the display). But it is possible to view 3D images without any problem from a distance of 25 to 35cm because the appropriate distance can be adjusted by fine-tuning the distance between the LCD panel and the parallax barrier, Hasegawa said.

When 3D images are shown by using a parallax barrier, the pixels of a panel are alternately allotted to the right and left eyes, lowering the resolution in the horizontal direction by half.

In 2002, Sharp announced a technology that enables to view 3D images with the naked eye by using a parallax barrier. And, during the period from 2002 to 2005, it had applied the technology to several devices including mobile phones and notebook PCs. But, partly due to the shortage of contents, those efforts did not yield satisfactory results, Hasegawa said.

Three Problems Solved
In the past, Sharp's 3D LCD display had the following three technical problems. First, its brightness and resolution lowered when 3D images are displayed. Second, a parallax barrier made the display thick, making it difficult to freely design mobile devices. Third, 3D images could be viewed either in the longitudinal or horizontal direction, and it is difficult to employ the display for devices that can be used both in the longitudinal and horizontal directions.

Sharp said that the new 3D display does not have those problems. As for the first problem, it doubled the resolution and the brightness by scaling down the TFT (thin film transistor) of the LCD panel. The new display has a screen size of 3.4 inches and a pixel count of 480 x 854.

The resolution of the panel is 240 to 330ppi for 2D images and 120 to 165ppi for 3D images. The brightness is 500cd/m2 for 2D images and about 250cd/m2 for 3D images. But it is possible to increase the brightness of the LED backlight only when 3D images are displayed, Sharp said. The resolution and the brightness of the 3D LCD display that the company was mass-producing in 2002 were 128 to 166ppi and 250cd/m2, respectively, for 2D images.

Furthermore, Sharp reduced cross-talk, a phenomenon where the images for the right and left eyes interfere with each other, by attaching the panel equipped with a parallax barrier to an LCD panel more accurately.

In regard to the second problem, the new 3D display has a touch panel integrated with the panel having a parallax barrier to reduce the thickness. Specifically, electrodes for a capacitive touch panel are formed on the front side of the panel, realizing a thickness equivalent to that of a touch-sensitive 2D LCD display.

As for the third problem, the 3D images shown by the new display can be viewed both in the longitudinal and horizontal directions by changing the control of the liquid crystal inside the parallax barrier in accordance with the tilt of the display. Also, passive drive elements are used to control the liquid crystal molecules inside the parallax barrier so that the transmittance does not lower as much as that of a display using active drive elements such as TFTs.

Silence on Nintendo 3DS
The new 3D display is expected to be used for the Nintendo 3DS, a portable game console that Nintendo Co Ltd is planning to release within fiscal 2010. The Nintendo 3DS allows users to view 3D images with the naked eye. Sharp has been providing its LCD panel for the Nintendo DS/DSi.

When asked about this at the press conference, Hasegawa said, "We would like to avoid commenting on our users' individual projects. We are now in talks with a mobile phone maker. But we cannot comment on businesses with game makers because, if we did, you could easily guess the name of a company."

By Shinya Saeki, Nikkei Electronics