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Anything but rectangular as Sharp offers Free-Form Display

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Displays have always been squeezed into a rectangular straitjacket. Even if a display has rounded corners or is curved, the basic form is rectangular. Now, here comes Sharp Corp. with its revolutionary Free-Form Display to set displays free. The FFD allows great freedom in the design of display shape. Sharp developed the panel by implementing gate drivers within pixel areas, not at the edges as in conventional panels. Sharp calls it in-pixel gate driver monolithic (IPGDM) technology.

Anything but rectangular as Sharp offers Free-Form Display

"Escape from a one-shape-fits-all world. The Free-Form Display promises to greatly expand display panel applications. Make it round, put a hole in the middle or maybe include some cutouts" said Akira Imai, general manager of Development & Strategy at Sharp's Display Device Development Division.

Until now, panel manufacturers have been preoccupied with large size, high resolution and picture quality in their pursuit of high-performance displays. But the day will soon dawn when these features no longer confer a competitive edge.

So what's next? Sharp demonstrated the FFD display and the MEMS display, which it is developing with Qualcomm, in Osaka last month and then last week in Tokyo. Sharp believes it can maintain its competitiveness with the freedom of display design conferred by FFD and the higher performance attainable with the MEMS display.

Sharp is trumpeting panel design as its new competitive edge. The company disclosed the concept of a frameless display, albeit without technical details, at CEATEC 2013 held at Makuhari, near Tokyo, last October.

Frameless concept at CEATEC 2013
Frameless concept at CEATEC 2013

From ultra-narrow frame to freedom in design

FFD goes well with IGZO
Sharp applied the in-pixel driver allocation technology to IGZO panels. Conventionally, gate drivers are fabricated in bulk, so how to allocate driver circuits in pixels was a technical challenge, according to Yasuhisa Itoh, unit general manager of Sharp's Display Mode Development Center.

The dispersed allocation of gate drivers in the pixel areas sacrifices the aperture ratio slightly. But an IGZO panel has smaller pixel transistors thanks to electron mobility roughly 10 times that of an a-Si LCD panel, so the slight deterioration in aperture ratio is no big deal, Ito said.

The technology itself is applicable to conventional a-Si TFT or low-temperature polysilicon LCD panels. But in the case of an a-Si TFT LCD panel, deterioration of the aperture ratio matters. For LTPS panels, though the technology is applicable, the panel size is subject to limitation.

Thus, the combination of IPGDM technology and the IGZO panel is advantageous, according to Ito.

Together with the Free-Form Display, Sharp showed the MEMS display as another candidate next-generation display. The prototype was a 7-inch display with a resolution of 1,280 and 800 pixels. The MEMS display features operation in a wider temperature range, down to as low as -30 degrees centigrade, and high color reproduction, about 15% wider than the NTSC triangle in the chromaticity diagram.

The FFD display is developed and fabricated at Sharp's Yonago fab using a 2.5-generation (405x515mm) line, which is also used for pilot production of MEMS displays. Imai said that the initial cost may be higher than that of conventional panels, but when production shifts to a larger-mother-glass line, the cost gap will eventually be eliminated.

Sharp is targeting in-vehicle displays as the first FFD application and is negotiating with automakers. Plans call for the market introduction in 2017 of cars equipped with the displays.

Press release:
Sharp Develops Free-Form Display, Enables Vastly Greater Design Freedom for Displays

Related articles:
Sharp to manufacture IGZO panels for smartphones on 8G substrates (Oct. 17, 2013)
Sharp to change to new IGZO structure within this year (June 5, 2012)
Sharp to introduce new IGZO technology for cost-competitive high-resolution small/medium LCDs (Apr. 22, 2011)

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