Sunday, September 19, 2010

How touchpad of a laptop work?

It was a curiosity to know the internal details of one of the most used 6x6 cm2 part of a laptop. My curiosity increased with diffrent behavior of the touchpad with different objects. For example, it works well with fingers but a pen, pin, or paper are not entertained.

So how does it work?

It is based on concept of capacitive difference on two parallel plates. Each of these plates have a grid of conductors. When we put our finger on the surface, it creates a charge difference on this surface and the difference of capacitance is sensed by the hardware.

This difference is mapped to mouse motion on our screen.

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