The main goal of any
mouse is to translate the motion of your hand into signals that the computer
can use. Almost all mice today do the translation using five components. Two rollers inside
the mouse touch the ball. One of the rollers is oriented so that it detects
motion in the X direction, and the other is oriented 90 degrees to the first
roller so it detects motion in the Y direction. When the ball rotates, one or
both of these rollers rotate as well. The following image shows the two white
rollers on this mouse. On either side of the disk there is an infrared
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. An on-board
processor chip reads the pulses from the infrared sensors and turns them into
binary data that the computer can understand. The chip sends the binary data to
the computer through the mouse's cord.
