4 ms·
When your finger gets close to the [touch] screen it causes a disturbance in the *magnetic* field that the electrodes sense. Surely they mean electric field -
by robocat 2y ago
When your finger gets close to the [touch] screen it causes a disturbance in the *magnetic* field that the electrodes sense.
Surely they mean electric field - for a capacitive touch screen.
- constantcrying 2y agoHow do you cause a disturbance in an electric field without causing a disturbance in the magnetic field?
- robocat 2y agoTo imply capacitive touch sensing uses magnetics is just so wrong - I can't imagine how someone trying to be technical could make such an egregious error. A material can affect an electric field without affecting a magnetic field: electrically conductive (versus insulator that won't affect a field so much except via dielectric effects). A material can affect a magnetic field without much affecting an electric field e.g. ferrites are non-conducting. A finger changes the capacitance between two "plates" and that is what is detected. Also the attached drawing shows diamonds but I've only ever seen flat wires myself (when looking closely at touch screens you can sometimes see the transparent sense wires). But I'm no specialist and I don't know how correct the drawing is.
- constantcrying 2y agoChanges in the electric field of a capacitor cause changes in the magnetic field. Electric and magnetic fields aren't Independent. Again, I asked about disturbances, Maxwells equations make it pretty obvious that changes in one cause changes in the other.
- robocat 2y agoPedantically correct but rather irrelevant to the topic of capacitive touch sensors. Your point just isn't helpful.
- marcosdumay 2y agoWell, it's a disturbance on the AC properties... so both. But yeah, we usually talk about capacitance as an "electrical-only" phenomenon. It's quite weird to se it referred as magnetic.