LG has announced plans to sell televisions that incorporate both 4K ultra-high definition resolutions and OLED panels.

The firm said a curved 65in (165cm) set would go on sale in Europe, South Korea and North America in September.

It calls the move a "first" since other firms sell models that offer either one or the other technology, but not both.

But while LG described it as a "game changer", one expert said the move "did not make economic sense".

Sony and Panasonic showed off their own prototype 4K OLED (organic light-emitting diode) sets at the Consumer Electronics Show in Las Vegas in 2013, but have opted not to put them into production.

The two companies offer 4K sets based on synthetic LED tech instead.

The difference is that OLED makes use of a carbon-based compound that emits light when struck by an electric current.

This allows TVs to do away with a backlight, meaning that pixels can offer deeper blacks when they are not in use, allowing manufacturers to boast improved contrast ratios - similar to what used to be available via plasma screens before they were discontinued.

Samsung - the world's bestselling TV maker - did release two of its own OLED sets in 2013, but they both had 1080p resolution, offering about four times less definition than 4K. Its website says both are "no longer available".

BBC News