Apple is using a secret facility in California to design and manufacture prototype MicroLED screens, according to a report from Bloomberg. Engineers are said to have produced fully functional Apple Watch-sized MicroLED screens at the facility, with a view to using the technology commercially for the first time in the watch. The Apple Watch currently uses OLED screens from LG Display.

MicroLED is a complex new emissive display technology where, like OLED, each pixel gives off its own light instead of relying on backlighting for the entire panel. This can give MicroLED excellent contrast, power efficiency, and viewing angles without OLED's compromises on brightness or longevity. Samsung is also working on MicroLED and showed off a 146-inch modular TV using the technology at CES in January. The TV, dubbed “The Wall,” will supposedly go on sale in August, although no price has been announced.

Apple's interest in MicroLED technology has been established for some time. It bought the startup LuxVue in 2014, and there have been many subsequent reports on how the purchase might be put to use. Last year Nikkei said that Apple planned to use MicroLED in the Apple Watch, identifying a facility in Taoyuan, Taiwan as being dedicated to the tech's development. The facility was previously owned by Qualcomm and used for Mirasol displays.

Bloomberg speculates that if Apple were to master the design of MicroLED to the point where it could be mass-produced for use in mainstream devices, it'd be the first time Apple is able to design screens “end-to-end.” But since the report also notes that Apple will likely have to outsource the actual manufacturing of its screens, the result may not be too different to what happens today, where companies like Samsung and LG Display produce LCD and OLED panels to Apple's designs and specifications.

At this point, though, MicroLED isn't a mature technology, and Apple's move into actually manufacturing screens itself — even at a small scale for testing purposes — is further evidence of the company wanting to have more of a say in what goes into its products. If Apple is able to master certain aspects of designing MicroLED screens and keep its breakthroughs to itself for as long as possible, it may still be able to hold advantages in quality even if the panels have to be made by somebody else.