Input Devices—Keyboard and Mouse

You can get both the mechanical and the optical mouse in both wired and wireless forms.

Mechanical

When you move a ball mouse, two rollers track the X and Y movement of a rubber ball. The rollers each connect to a shaft, and the shaft spins a disk with holes in it. When a roller rolls, its shaft and disk spin. On either side of the disk, there is an infrared light-emitting diode (LED) and an infrared sensor. The holes in the disk break the beam of light coming from the LED so that the infrared sensor sees pulses of light. The rate of the pulsing is directly related to the speed of the mouse and the distance it travels.

In this optomechanical arrangement, the disk moves mechanically, and an optical system counts ...

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