High-Definition, Low-Power Consumption Display Achieved with Crystalline Oxide Semiconductor (OS)

Smartphone with IGZO:
(Distributed by NTT DOCOMO, INC. / Manufactured by Sharp Corporation)

Our crystalline oxide semiconductor technology is used widely in the display industry. For example, our technology has been used in smartphones produced by Sharp Corporation since 2012.
FETs using crystalline oxide semiconductors can not only greatly reduce power consumption owing to their extremely low off-state current, but facilitate their miniaturization (and thus making high-resolution displays possible) by their high current capability.
We are engaged in research and development of various displays fabricated using the crystalline oxide semiconductor material, aiming for the incorporation of this technology into mobile devices that demand high display resolution and low power consumption.
The application possibilities for this technology are still expanding to displays such as an 8K display (pixel count: 7680 × 4320), a foldable display®, a multi-display, a display with touch sensors, an ultra-high resolution display, etc.
The extremely low off-state current of FETs fabricated using the crystalline oxide semiconductor material also enables a driving mode in which the display is refreshed less frequently when displaying a static image (idling stop or IDS driving1). This driving method is expected not only to reduce power consumption but to achieve a display that puts less stress on the eyes.

▲Demonstration Video of Foldable Display

1) Idling-Stop (IDS) Driving Technology
IDS driving is a display method for still images, utilizing a feature that a video signal can be held by crystalline OS. In a typical display, over 60 images are displayed per second, which are perceived as a single image or a moving image with human eyes. In other words, many images are actually displayed at high speed to display one still image. With the IDS driving, the number of times an image is re-written while displaying a still image can be reduced to, for example, once every 5 seconds. It is like looking at a natural object or at information on paper. Moreover, when this technology is used in a reflective display, a backlight becomes unnecessary, which enables ultra-low power consumption. This technology provides an electronic book reader with ideal functions such as eye-friendly and long-time driving.

OLED Display

▲Super High-Definition Display (Super Hi-Vision as the next-generation TV standard)
13.3-Inch 8K Display (pixel count of 7680 × 4320)[1]

[1] S. Kawashima et al., “13.3-in. 8K x 4K 664-ppi OLED Display Using CAAC-OS FETs”, SID Symp., Dig. Tech. Pap., 45, 627 (2014).

▲The World's Highest Definition2)[2]
2.78-Inch 1058 ppi Display (pixel count of 2560 × 1440)
2) This display has the world's highest pixel density among displays using thin-film transistors on glass substrate, as of the end of December 2015, according to our own research.

3) The world's largest 8K OLED display, as of the end of December 2015 (according to our own research).

[2] K. Yokoyama et al., “A 2.78-in 1058-ppi Ultra-High-Resolution OLED Display Using CAAC-OS FETs”, SID Symp, Dig. Tech. Pap., 46, 1039 (2015).
[3] D. Nakamura et al., “An 81-in. 8k x 4k OLED Kawara-Type Multidisplay that Provides a Seamless, Continuous Image”, SID Symp, Dig. Tech. Pap., 46, 1031 (2015).

▲8.7-Inch Tri-fold Display with Touch Sensor[4]
Image provided by Getty Images

▲13.3-Inch 8K Bi-fold Display (pixel count of 7680 × 4320)[5]

[4] K. Watanabe et al., “An 8.67-in. Foldable OLED Display with an In-cell Touch Sensor”, SID Symp, Dig. Tech. Pap., 46, 246 (2015).
[5] K. Takahashi et al., “13.3-inch 8k4k 664-ppi Foldable OLED Display Using Crystalline Oxide Semiconductor FETs”, SID Symp, Dig. Tech. Pap., 46, 250 (2015).

Liquid Crystal Display

▲5.9-Inch Touch-Sensitive Reflective Display (pixel count of 1536 × 2048)
Image provided by Getty Images

[6] D. Kubota et al., “Reflective LCD with High Reflectance and Color Reproductivity for Reduced Eye Strain”, SID Symp, Dig. Tech. Pap., 46, 1084 (2015).

* foldable display is a registered trademark of Semiconductor Energy Laboratory Co., Ltd.
(Japanese trademark registration No. 5680115).