Microsoft has secured three patents covering the design of its keyboard Touch Cover accessory for the Surface tablet.
The US Patents and Trademarks Office (USPTO) granted Microsoft the patents on Tuesday based on applications it filed last May, about a month ahead of the tablet's official launch where as a key design innovation.
The' cover, while its Type Cover is a more fully-fledged 6mm keyboard with mechanical keys.
The patents cover the "ornamental design for an electronic tablet with input device coupling", referring to the magnetic connector that allows users to "click" the keyboard in place.
The Surface RT was released in the fourth quarter of 2012 in some markets but in that time only managed to ship 900,000 units, according to IDC, offering it a tiny fraction of the otherwise currently dominated by Apple.
Microsoft's tablets launched at a time consumers began showing a preference for smaller screen and cheaper devices, like the iPad mini, at the same time as morebegan to arrive.
In February, Microsoft expanded distribution of the, and released the Intel-based Surface Pro, however, it .