Patent application filed by Apple for the Digital Crown shows it being used on the iPad
The Digital Crown on the Apple Watch, can be used for zooming, scrolling and can return you to the home screen. On the iPhone or iPad, it can be used to raise or lower volume, resize text, lock the touchscreen or to take a photograph. The patent application adds, "In some examples, the device may not have a border region and may instead have a surface composed only of touch screen." This appears to be quite timely since there is speculation that the 2017 Apple iPhone will feature an edge-to-edge screen with no bezels for a home button.
Early speculation has a Touch ID button embedded in the screen on the 2017 iPhone, but a Digital Crown might be a less complicated solution for Apple. We do need to point out that the patent application was filed in the first quarter of 2014, which does make it unlikely that it was filed with the 2017 iPhone in mind. Still, we could be on the verge of a major design change for next year's handset and the Digital Crown could be a useful tool.