I have a few questions regarding the technical details of the Apple Pencil:
How does the iPad differentiate between the Pencil and your hand (palm rejection)? Is the Pencil creating some sort of a stronger electrostatic field at its tip compared to the intrinsic "field" of our skin, which the iPad's touch screen then measures?
- I have a 3rd party active stylus that does not require a bluetooth connection with the iPad. For this stylus the palm rejection works just as fine as with the Apple Pencil. So clearly, this feature must work independently from the BT connection with the iPad. The electric field created at the tip is the only plausible explanation that comes to my mind.
- The iPad also offers a setting called "Only draw with Apple Pencil" in which case the iPad won't allow any drawing with fingers; fingers will be used only for scrolling. This mode also works w/o any issues for the 3rd party stylus. Again, my assumption of a different electric field (compared to human skin) created by the pencil tip would explain how the iPad can tell Pencil and Finger apart.
Why doesn't the Apple Pencil work with other devices, such as smartphones (I tried with my OnePlus 6 and it didn't work)?
- Based on my assumptions from question 1, shouldn't the Apple Pencil work with any capacitive touch screen? However, this is not the case - it only works with supported iPads (also applies to my 3rd party stylus).
How does the tilt detection (eg, for drawing shading) work?
- Tilt detection also works with my 3rd party stylus, so again, this feature must work w/o the BT connection.
- My assumption: The touch screen measures the capacitance between screen and tip. Depending on the tilt angle, this capacitance changes, so the iPad can calculate the tilt of the Pencil.
I watched this video, but it didn't answer any of my questions above (kind of expected, because it was the Apple Pencil ad).