Chapter 18: Keyboards, Mice, and Pointing Devices^465
Optomechanical mouse This type of mouse uses light-emitting diodes
(LEDs) to sense mouse movements. This is the most common type of mouse
used with PCs today.
Optical mouse The optical mouse eliminates the use of mechanical devices
(balls, rollers, and wheels) and uses optical scanning to detect the movement
of the mouse over virtually any surface.While there have been any number of attempts to vary the design of the mouse, includ-
ing the new optical mice, the optomechanical mouse continues to be the most popular style
in use. The following discussion focuses on the optomechanical mouse, but the other
types of mice are discussed later in this section.Inside the Mouse
A mouse translates the motion of the user’s hand into electrical signals that the PC uses to
track a pointer across the monitor’s display. To capture the motion of the user’s hand, an
optomechanical mouse uses six primary components: Ball The ball is the largest and central part of the mouse. When the user
grasps the mouse and moves it over a mousepad or the desktop, the ball rolls
inside the mouse.
Rollers As the ball rolls inside the mouse, two rollers that touch the ball track
its rotation side to side and up and back.
Roller shafts The rollers are each connected to a shaft; as the rollers turn
in conjunction with the ball, each shaft turns an optical encoding disk that
is attached to it.Figure 18-19. A PC mouse