TR-Hybrid display optimises display switching modes

Article By : Julien Happich

The Semiconductor Energy Laboratory (SEL) in Japan has developed a smartphone-sized 4.38 inches hybrid display that combines two display technologies into one: OLED for its very high contrast and colour quality indoors, and reflective LCD for its high readability in bright outdoors.

The last SID conference enabled Semiconductor Energy Laboratory (SEL) to showcase their latest TR-Hybrid display, as it calls it (T for transmissive OLED and R for reflective LCD).

The Nikkei Technology reported about how the two displays are physically intertwined so as to allow the screen to switch from one mode to the other. The OLED part of the display sits at the back of a reflective LCD, with its emitted light being transmitted through holes cut in part of the reflecting electrodes. The reflective LCD and OLED displays are driven independently, their respective aperture ratios are 76% and 3.9%.

[SEL's hybrid display in OLED mode.]
__Figure 1:__ *SEL’s hybrid display in OLED mode.*

[SEL's hybrid display in R-LCD mode.]
__Figure 2:__ *SEL’s hybrid display in R-LCD mode.*

The lab was also able to reduce the display's power consumption by driving it with IGZO oxide TFTs running at low frequency. The report says SEL optimised its display driving method to improve the display contrast of the OLED from 1,111:1 to 2,850:1. The prototyped display had a resolution of 768×1,024 with a pixel density of 292ppi.

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