Mouse
The mouse was introduced with the Apple Macintosh and was
an immediate success. The mouse was the natural, intuitive, inexpensive
pointing device users wanted. But, it wasn’t until the early 1980s, when
Windows and its graphical user interface (GUI) was released, that the PC had an
operating system that could work with the mouse. Since that time, the mouse has
become a standard equipment on virtually all PCs.
Types of Mouse
There are three types of mouse units used with PCs:
· Mechanical Mouse
This is the older style of mouse used with early
Macintosh and PC GUI systems. In a mechanical mouse, the movement of a rubber
ball causes a pair of wheels to spin that sensors detect to send data signals
to the PC.
· Optomechanical Mouse(Wheel 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. A newer version of the standard optomechanical mouse is the wheel mouse.
The wheel mouse has a finger wheel located on it stop, typically between the
two buttons. The wheel allows the user to scroll forward and backward through a
document in place of clicking on a window’s scroll bar or using the PAGE UP and
PAGE DOWN keys or the cursor control arrow keys.
· 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. The optical mouse eliminates
the mouse ball, replacing it with a optical sensors that track the movement of
the mouse against the background of the mouse pad or whichever flat surface
it’s on. Optical mice have been around for a few years. The older design for
the optical mouse required a highly reflective mouse pad that had a printed
grid on it. The real draw back to this mouse, besides the fact it was slow, was
that if you lost the mouse pad, the mouse would not work on a normal flat
service that had a bit of texture or detail to it. Some surfaces, such as
glass, mirrors, or smooth, shiny, solid-color surfaces without detail, do not
work well with even the new optical mice.
The latest optical mouse designs include an optical
process that captures images of the surface underneath the mouse (called the
mousing surface) at a rate of up to 2,000 images per second. The mouse includes
a digital signal processor (DSP) that analyzes these images and is able to
detect even the slightest movement. The optical system of the mouse eliminates
the need for a mouse pad and works on virtually any flat surface except those
that are very shiny or reflective.
One real advantage to the optical mouse over the
optomechanical mouse is that it does not require internal cleaning. Because it
has eliminated all moving parts, the optical mouse does not pick up dust and
other debris that could clog up the optomechanical mouse and require it to be
regularly cleaned. Another advantage is that, according to manufacturer claims,
an optical mouse is at least 33 percent faster and many times more accurate
than an opt mechanical mouse.
· Wireless Mouse
A cordless mouse, also called a wireless mouse, is a
mouse that connects to a computer without the use of wires. Instead, the mouse
uses some manner of wireless technology, like Bluetooth, RF, or infrared radio
waves. Usually, a USB receiver is plugged into the computer and receives
signals from the cordless mouse.
Component of 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 mouse pad 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.
· Optical encoding disk
As the ball rolls, the rollers turn the shafts that spin
the optical encoding disks. The optical encoding disk has 36 holes along its
outside edge.
· Infrared LED and sensor
On one side of each optical encoding disk is a
light-emitting diode (LED) that shines an infrared light beam on the disk. On
the other side of the disk is a light-sensitive transistor that serves as an
infrared sensor. As the disk turns, the solid areas between the holes on the
disk break the LED’s infrared beam and the infrared sensor sees pulses of
light. The rate and duration of the light pulses indicate the speed and
distance of the mouse’s travel.
· Processor
The mouse has a processor that reads the pulses sent from
the infrared sensors and converts them into binary data, which is sent to the
PC’s interface over the mouse’s connecting cord.
Mouse Buttons
The mouse also has one, two, three, or more buttons (two
is the most common number of buttons on PC mice) that are connected to small
switches that also connect to the mouse’s processor. As the user clicks the
buttons to select an object on the screen or start a program or applet, the
process or converts the clicks into binary data that is sent to the PC.
Mouse Connectors
Nearly all mice sold
today have a six-pin mini-DIN (PS/2) connector. This connector, which was first
introduced with the IBM PS/2 system, has essentially replaced the DB-9 serial
connector that was used before that. Serial mice are still available, but since
newer PC systems rarely offer more than a single serial port and include PS/2
connectors for both the keyboard and mouse, the serial mouse has all but
disappeared. The PS/2 connector on the mouse uses four pins to connect and
communicate to the PC.
The mouse sends data and clocking signals to the PC using
very much the same techniques as the keyboard. A mouse uses pins in the
connector and wires in the cable for +5V power (pin 2), the clocking signal
(pin 4), a ground (pin 5), and a data signal (pin 6). The power connection supplies
+5V of electricity to the process or and LEDs.
Mice
are now available with USB, infrared (IrDA), and radio frequency (RF)
connections as well. The USB connector, is becoming a popular choice among
notebook PC users who wish to connect an external keyboard into a notebook’s
single PS/2 connection and still use an external mouse.
Cordless mice communicate with a PC through either an
infrared or an RF receiver. Many PCs now come with an IrDA receiver included,
but RF connections require an external receiver. External RF and infrared
receivers can also be added to a PC through a PS/2 or USB port. An
optomechanical mouse gets its power (+5V) from the PC over its interface cable,
but cordless mice do not have a power connection and, regardless of the type of
connection in use, run on a pair of AAA batteries.
Infrared connections are line of sight and have a limited
effective operating distance. The infrared connection must have a clear,
unobstructed line of sight to the receiver, which must be in a clear, open
location; a radio frequency connection doesn’t require a line of sight.
Operation of Mouse
A mouse typically controls the motion of a pointer in two
dimensions in a graphical user interface (GUI). The mouse turns movements of
the hand backward and forward, left and right into equivalent electronic
signals that in turn are used to move the pointer.
Different ways of operating the mouse cause specific
things to happen in the GUI:
· Left Click: pressing and releasing a button.
· Single-click: clicking the main button.
· Double-click: clicking the button two times in quick succession counts as a different
gesture than two separate single clicks.
· Triple-click: clicking the button three times in quick succession counts as a different
gesture than three separate single clicks. Triple clicks are far less common in
traditional navigation.
· Right-click: clicking the secondary button, or clicking with two fingers. (This brings
a menu with different options depending on the software)
· Middle-click: clicking the tertiary button.
Drag and drop: pressing and holding a button, then moving the mouse without releasing.
(Using the command "drag with the right mouse button" instead of just
"drag" when one instructs a user to drag an object while holding the
right mouse button down instead of the more commonly used left mouse button.)