CEATEC JAPAN 2017 Sharp appealed high resolution IGZO-TFT-LCDs

October 3-6, CEATEC JAPAN 2017 was held in Makuhari Messe. In this here, topics of display relations are picked up.

First of all, as concerns display module, Sharp appealed IGZO-TFT-LCDs aggressively. Concretely, 8K 27 inch HDR (High-dynamic-range rendering) monitor was exhibited as a flagship prototype. Its pixel size is 78 × 78 μm, and resolution is 326 ppi. High contrast ratio was realized by the area control technology (total 200 areas), to be corresponded to HDR. In short, light intensity from LED backlight in each area is controlled by synchronizing with image signal. Furthermore, high brightness same as 1000 cd/m² and over was gained. Of course, individual pixel could not be recognized by bare eye because of this size and resolution. The company will release this monitor as high resolution applications such as medical monitor, art monitor, and so on.

Picture 2. FFD for instrument panel

Picture 1. 8K 27 inch IGZO-TFT-LCD monitor

And also, the company has exhibited FFD (Free Form Display) for the instrument panel of automotive by IGZO-TFT-LCD technology. This is a free form and thin film display, which is composed of dual 20 inch IGZO-TFT-LCDs (4K1K：3840×1080 pixel) by parallel assemble technology. Its resolution is 197 ppi. Narrow bezel is realized by building in gate driver circuit into pixel. Aperture ratio of pixel is merely reduced by a few ％. Of course, gate driver circuit can be formed in the IGZO-TFT manufacturing process at the same time. In short, step number of IGZO-TFT manufacturing process is not increased. Its panel is decided to adoption in mass-production for automotive, yet.

Color purity is greatly enhanced by QD

As regards material for display, Nippon Electric Glass introduced QD (quantum dot) sheet, which was developed by NS materials (related company). As you know, in QD, excited luminescence color is controlled by grain size. This QD sheet is set on the blue LED unit as a component of LCD backlight module. Part of blue light from LED is converted to Red and green colors. For this reason, high purity RGB light is gained because of RGB 3 wavelength. Of course, color can be controlled by grain size and filling ratio of QD at will. Covering ratio of BT2020 (international standard of 4K/8K ultra-high resolution TV) of the conventional white LED + YAG phosphor is mere 66.6 %；on the other hand, that of blue LED + QD sheet is 92.5 ％.

As picture 3 and 4, RGB color samples and TFT-LCD monitors with the conventional LED and this blue LED ＋ QD sheet were exhibited in the booth. By making use of QD sheet, color purity and contrast ratio can greatly enhanced.

Gen 4 OLED material was introduced by venture company

As concerns OLED technology, venture company “Kyulux” appealed a new high efficiency and high color purity emitting materials. In this technology, TADF (Thermally Activated Delayed Fluorescence) which was developed by Prof. Adachi of Kyushu University is effectively used. Concretely, TADF is used as a host, and the conventional fluorescence material is used as a dopant. In short, exciton is generated by TADF, and then, fluorescence dopant is emitted by movement of excitation energy. The company has named this emission mechanism (Hyperfluorescence) as the 4th generation (1st：the conventional fluorescence, 2nd：phosphorescence, 3rd:TADF only). Luminance efficiency of Hyperfluorescence is same as that of 2nd and 3rd, and also, color purity of Hyperfluorescence is same as that of 1st. However, manufacturing cost of Hyperfluorescence can be reduced by 1st level.

Picture 5. Green color panel

In green device, FWHM (full width at half maximum) of TADF device is 89 nm；on the other hand, that of Hyperfluorescence device is 32nm. And also, in red device, that of TADF device is 90 nm；on the other hand, that of Hyperfluorescence device is 43nm. In short, color purity can be improved greatly, and also, quantum efficiency is almost 100 ％ because of use of TADF. In the booth, green mono-color panel and area-color panel with orange and yellow color were disclosed.