The company says the prototype screen still supports full HD resolution, 5000:1 contrast ratio and 120Hz refresh rate, despite its slim dimensions.
The 3.9mm panel is around 7mm slimmer than the company's current production LED-lit displays, and 46mm thinner than conventionally-lit LCDs.
It also undercuts the most recent slim displays shown by LG Display, which are 5.9mm thick.
It could take a couple of years before this Needle Slim technology is commercialised, but it's thought the panel will make it possible to build large-screen TVs not much more than 2cm thick.
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