Here in this presentation working of Keyboard and working of roller mouse,optical mouse and touch pad is also explained in detail.

1. Working of Keyboard
and Mouse
Team - 7
Submitted by-
Abdul Kalam Ashad.A (13MX01)
Anish Kumar.B (13MX04)
Mohan Raj.T (13MX30)
Sapthagirinathan.D (13MX39)
Sudharsan.S (13MX47)

2. What is a keyboard?
 A Keyboard is an input device that uses an arrangement of
keys or buttons that have letters, numbers or symbols that
when pressed the letter on the keyboard then shows up on the
screen.
 To display some symbols you need to press combination of
keys then the symbol you desire to display on the screen.

3. Components of keyboard
 Most keyboards have 80 to 110 keys.
 The inside of the keyboard is consists of a processor and the printed circuit board.
 The numbers and letters on the keyboard are displayed keycaps--these are the
buttons.
 The keys are nested on rubber dome switches that contain carbon in the centre.
This causes each key to be pressed down and come right back up when you do not
press it anymore.

4. Communication
 The keyboard connects to the computer via a six pin male plug or a PS/2 plug.
 Keyboards and computers work together in a bi-directional format.
 These bi-directional lines are the clock line coming from the keyboard and the
data line coming from the computer.
 The computer will send a signal to the keyboard through the clock line letting
it know that the line is clear to send. If the line is not clear, the keyboard will
hold the information until the line opens.

5. Working of keyboard
 When the key is pressed a small rubber dome is pressed down it connects
a pair of conducting lines together on the circuit.
 It sends an electrical signal to the processor built into the keyboard.
 When this signal reaches the processor, It is aware of the pressed key's
location on the keyboard grid.
 The location on the grid is compared to a character map stored in the
keyboard's memory.
 A match between the location and a defined character is quickly
established, at which point the keyboard transmits the data to the
computer.

7. Virtual Keyboard
Rollup keyboard
Multimedia or Gaming keyboard

8. MOUSE
 A device that controls the movement of the cursor or pointer on a display
screen. A mouse is a small object you can roll along a hard, flat surface.
 Its name is derived from its shape, which looks a bit like a mouse, its
connecting wire that one can imagine to be the mouse's tail, and the fact that
one must make it scurry along a surface.

9. Types Of Mouse
ROLLER MOUSE
OPTICAL MOUSE
TOUCHPAD

10. Components of Roller Mouse
1.
2.
3.
4.
5.
Switch detects clicks of left mouse button.
Switch for middle button.
Switch for right button.
Old-style connection to PS/2 socket on computer.
Chip turns back-and-forth (analog) mouse
movements into numeric (digital) signals computer
can understand.
6. X-axis wheel turns when you move mouse left and
right.
7. Y-axis wheel turns when you move mouse up and
down.
8. Heavy rubber wheel.
9. Spring presses rubber ball firmly against X- and Yaxis wheels so they register movements properly.
10.Electrolytic capacitor
11.Resistors

11. Working of Roller Mouse
 A mouse contains a rotating ball with two rollers held at right angles to each
other which touch the ball. The rollers register the x and y axis movements of
the ball.
 Each roller is attached to an optical encoder, a disc which has gaps in its surface.
The rotation of the encoder interrupts two beams of light between the LEDs and
their detectors.
 These pulses of light are fed to the computer and are used to determine the speed
and direction of the mouse's movement.
 When the mouse move, or press or release mouse buttons, the mouse circuitry
sends data to the host (PC), indicating what state changes have occurred since
the previous state indication.

12. Components of Optical Mouse
1. An LED at the back generates red light
and shines it horizontally, from the back of
the mouse toward the front (from the left
to the right of this photo).
2. A plastic prism bends (refracts) the light
from the LED at an angle, down onto the
desk.
3. A light-detector chip measures light
reflected back up from the desk,
converting the analog movements of your
hand into digital signals that can be sent to
your computer.

13. Continue…
4. The scroll wheel at the front of the mouse is mounted on a switch mechanism
that detects both how much it's rotated and whether you've pressed it (it
functions like the central button of a conventional mouse). Rotations of the
scroll wheel can be detected in a variety of different ways. Some mice use
potentiometers (broadly, variable resistors), similar to the volume control on a
radio but able to turn around multiple times. Others use various kinds of rotary
switches or optical (rotary) encoders to convert analog wheel movements to
digital signals.
5. A microswitch detects when you press the right mouse button. There's an
identical switch on the other side to detect the left mouse button.
6. The USB or PS/2 cable connection carries digital information from the mouse to
the computer.

14. Working of Optical Mouse
 The LED produces a red light that is emitted horizontally.
 A plastic prism refracts the light onto a surface.
 Light reflected back up from the desk is detected by a light-detector
chip which converts analog movement into digital signal.
 When you press the right mouse button or left mouse button the micro
chip detects and transmit the digital signal to computer.

15. Touchpad
A touchpad is a simple, easy and reasonable pointing device.
It allows the users to drag their fingers along in the direction they want the
mouse pointer to go.

16. Working of Touchpad
 Its surface tracks the motions and pressure of a finger and correlates it to the
position on-screen.
 There are two common technologies that enable touchpads to work , capacitance
and conductance.
 Capacitance is the most common method and enables the touchpad to hold an
electrical charge.
 It creates two arrays, one vertical and one horizontal, and when your finger
touches a spot on the touchpad, it locates the coordinates of that location.
 The pad sensors then convert the location from the touchpad to the location on
the screen.
 Most newer touchpads also have a function for scrolling, just as a middle mouse
button does.
 There is a location on the touchpad called a hot spot that enables this function.

17. References
Websites
http://www.ehow.com
http://www.howstuffworks.com
http://www.Wikipedia.com
http://www.computer-hardware-explained.com
http://www.pcsupport.com
http://www.techrepublic.com