I had a brief memory from childhood come back to me- playing the nintendo ds for the first time and being able to touch the screen to play various games and how blown away I was by it.
Typing this 20 years later on my iPhone, I guess I’ve taken it for granted all this time, but im curious to know how “touch screen” works and how it differs from the old school button pressing interface?
In: Engineering
There are 2 types of touch screen.
One is the old type, “resistive touchscreen”, that you need to press with a sharp object like a stylus or fingernail. There are two layers made of transparent conductive rows on one layer and columns on the other. Pressing squeezes a row and column together, completing a circuit and telling where the press is.
The other is the new type, “capacitive touchscreen”. You have a grid of transparent capacitors under a glass layer. Because your finger is slightly conductive, it affects the charge of the capacitor under your finger which can then be detected to know where you’re pressing. This needs something conductive like your finger or a special touchscreen stylus.
A third way of digitizing data for some large displays, can be cameras in corners pointing at reflectors along the opposite side of the screen. Those can be placed along the edges of existing dry erase boards or projector screens to digitize finger/pen touches. 80″ Smart boards that used room projectors had those installed.
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