In January 2020, Apple has obtained the patent of "touch based stylus input", and now it has obtained the latest patent of the same name. There are few amendments, both approved patents involve setting a flexible sensor on the user's fingertip to receive tactile input**
Apple said in the patent that the tactile input can be received at the user's natural holding position. In addition, the stylus can effectively distinguish the tactile input from the user and distinguish the continuous tactile input provided when holding the stylus naturally from the effective input. The patent states that when someone uses Apple pencil or any stylus, they are unlikely to touch [iPad] at the same time( https://apple.pvxt.net/c/1251234/435400/7639?u=https%3A%2F%2Fwww.apple.com%2Fcn%2Fipad%2F ) Or similar devices.
Apple believes that when users hold a stylus or other touch based input device, users may be limited to the input options provided. Therefore, the additional input capability integrated into the input device will provide users with expanded input capability without operating additional input devices at the same time.
To achieve this goal, pencil will add a "low-key" sensor, such as capacitive sensing device. Tactile input can be received in the user's natural holding position. Before the patent application, there were some patents on the base and tip of a stylus like apple pencil, many of which even used the same drawings.
In December 2019, one such patent relates to how Apple pencil's stylus uses tactile feedback to better simulate the feeling of painting on paper. A similar patent in 2015 involved the same purpose, but involved the entire stylus. Another example is an Apple patent filed in December 2019, in which the stylus uses a camera to decipher and record the physical features of the surface.