Microsoft's "wearable personal information system" includes a small computing device that can be locked into a frame that's housed on multiple wearable bands.
The device could be removed by pressing down on the top surface and mounted to a dock that would be secured magnetically, the patent suggests.
The device can be mounted onto the dock without its frame, allowing it to charge and or swap data with another bit of hardware.
The dozen images included in the patent indicate the back surface of the device would have an optical sensor — potentially used to measure a biometric parameter, such as heart rate — electrical connector and a data connector.
Input sources to the processor include the touchscreen, optical sensor, and other sources such as the GPS unit with internal compass.
In other words, the patent describes many similar features that are appearing in devices such as Samsung's Gear range and LG's forthcoming Android Wear watch. Despite gathering rumours and hints at new product lines, Apple is still to reveal its own smartwatch, dubbed the iWatch.
As for Microsoft, the company has made no secret of its attempt to focus more on the Internet of Things, a blanket term that can cover wearable tech.
The company was thought to be working on an answer to Google's Glass last year, with those efforts driven by Alex Kipman, who had been leading Microsoft's Xbox incubation and worked on the Kinect sensor.
Microsoft's smartwatch efforts were reportedly being led initially by the Xbox team but then moved to its Surface team. Rumours about a Microsoft smartwatch — such as that it could be housed on a variety of different bands — are consistent with the designs in the patent, including that it would come with a heart-rate monitor.
A prototype of the device was also said to be running on a modified version of Windows 8 that supported integration with other Windows devices. Other rumours suggested it had 1.5-inch screen, 6GB of storage, and supported LTE networks.