Japanese smartphone screen makers keep packing in the pixels. The latest to do so is Sharp. Today it said it will put a 5in, 1920 x 1080 LCD into production later this month.

A quick tap or two on the calculator reveals that's 441 pixels per inch - rather more than the 326ppi the iPhone 5 delivers.

Sharp said the display is built on Continuous Grain Silicon (CG-Silicon) thin film transistor technology, a technique that creates pixels that can switch up to 600 times as quickly as those in screens based on the traditional LCD foundation, amorphous silicon, can - and, indeed, better than Sharp's own Indium, Gallium, and Zinc Oxide (IGZO) transistor technology, which offers an electron mobility 25-30 times that of amorphous silicon.

In the past, Sharp has said it will use IGZO for displays of up to 300ppi, and CG-Silicon for screens with a greater pixel density than that.

It also requires few layers to be sandwiched together, making for much thinner panels, or allowing manufacturers to integrate image processing and display control circuitry into the display itself. Being thinner, more light passes through the panel from the backlight making for a higher contrast image.

Sharp devised CG-Silicon with Japan's Semiconductor Energy Laboratory. ®