how can touch screen distinguish my finger from other objects touching it?

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how can touch screen distinguish my finger from other objects touching it?

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It can’t.

Imagine there’s a thin layer of very weak electricity on the screen, when you put your finger anywhere on it you will affect that electricity, since it can flow through your finger. Then by using fancy math it can calculate *where* on the screen your finger is.

Any object that can conduct electricity will work, there are both pens and gloves made specifically for touch screens for example.

It does not try, this is kind of an unwanted fluke. Touch screen manufacturers are trying to make their screens detect things like general pens and gloves but the technology used makes this hard. In fact some rugged devices use older worse touch technology to allow them to be used with gloves.

The current touch screen technology is capacitive touch sensitive. There is a grid of thin wires over the screen that with certain sensors can detect the capacitence in the area. In rough terms things which conduct electricity increases the capacienence. For example a human finger. But also things like water. However gloves and most other objects do not work. Even the glass or plastic on top of the screen does not have much of an effect on the capacitence and are therefore invisible to the touch screen.

There are special gloves you can get with materials sown onto the fingers that does increase the capacitence. These can be used on touch screens as well.

As others have said, the touchscreen can’t, but the software can attempt to differentiate between where a stylus is touching the screen and where your palm is. It can consider the size of the touches, how they are moving and potentially other metrics to do this.

Short version: It can’t
Long version: It depends.
If you look at a phone / tablet/… screen than it will only detect “flesh” or skin.
It won’t be able to detect something like you wearing a glove, a metal object,…
This is because of the type of touch screen that is used, it can “sense” the electric/ magnetic field that your finger has (Inductive/capacitive screen).
In an industrial setting (e.g. where gloves are required) we use a “Resistive screen” this will detect anything.
Because it uses the difference in electricity that is generated from crystals in the screen when they get pressed on ( by you, a metal object,…).

It doesn’t know the difference. I keep my phone in my side pants pocket and as it gets bumped around it opens and activates apps or changes the layout. Drives me nuts. I don’t use a passcode because I use my phone constantly while at work.