5. Input Device :keyboard

6. Types of key switch Components of Keyboard Keyboard switches
Keyboard processor or circuitry
Key matrix
Types of key Switches
Capacitive switch
Hall effect switch
Opto electronic switch
Membrane switch
Mechnical switch

7. Types of key switch
Capacitive switch: two plates of the capacitor are brought closer when the key is pressed.
Change in capacitance of switch changes and change in capacitance is detected in terms of voltage.
Based on the switch open/close voltage is received this voltage is converted into proper signals to inform CPU.
Lifespan 20 millon key strokes.

8. Capacitive key switch

9. Types of key switch Hall effect switch:
magnetic field is applied to any device the resistance of device will be increases or decreased(current starts flowing)
This allow current flow
Lifespan 100 million keystrokes

10. Types of key switch
Opto-electronic switch: have LED light generate light when electric power is applied. uses photo- transistor which allow current to flow in the circuit.
When key is pressed not pressed the light from LED falls onto photo-transistor
When key is pressed the value will be produced at the output Vout

11. Membrane switch

12. membrane switch: it is multi layered plastic or rubberuses the row and colum conductor sheets.
Mechanical switch: it uses two metal pieces or contacts .
Rubber dome:madeup of polyester domes
Refered as direct switches.
Mechanical switch

13. Keyboard Interfaces Connects to PC KEYBOARD KEYBOARD CONNECTOR
Inside keyboard a processor and circuit which carry information to or from that processor.
Keyboard controller is single chip contains memory RAM, processor ROM(control operations of keyboard)
Key matrix: row and columns made up wires and each key act like switch
Key matrix is grid of circuits when key is pressed the row wire makes contact with colmn wire and completes the circuit . KM passes current to keyboard controller .
Keyboard controller will detects the closed circuit and registers the key press and controller read the key pressed.

14. Keyboard Interfaces KEYBOARD CONNECTOR
Interface between keyboard and pc
AT keyboard connector(DIN5)
PS2 keyboard connector or(MIN-DIN6)
USB connector
Uses 5 pins: KBDCLK(provide clock pulse), KBDAT(send/recive data),KBRST (reset keyboardinternal buffer),GND(ground),VCC(+5v provides power to keyboard)
PS2 keyboard connector or(MIN-DIN6): With 6 pins

16. USB keyboard connector:
USB keyboard connector : uses 4 pins VDC(+5V),DATA- carries -ve data signal,DATA+it carries +ve data Signal,
Keyboard working:key is pressed it pushes down the rubber dome
Dome tuches a pair of conductive lines on circuit
Allow current flow

17. Mouse:
Mechanical Mouse : Mechanical Mouse uses ball for the movement of cursor on thecomputer screen. When the ball is rolled in any direction, a sensor of the mouse detects it and also moves the mouse pointer in the same direction.
Optical Mouse : Optical Mouse uses Laser rays for the movement of cursor on the computer screen. It is an advanced pointing device. Movement is detected by sensing changes in the reflected light rather than the motion of a rolling sphere.
Cord-Less Mouse : Cord-Less Mouse is battery driven and does not need any wire for the physical connection with the motherboard. It transmits data through infrared or radio signal.

18. Mechanical mouse

19. Mouse types
1.Mechanical mouse: a rubber ball rolls as the mouse is moved across table top or mouse pad.
The wheels are referred as encoders have tiny metal contact points on rims
Location of mouse is identified by how many times the contact points have touched the bars.
mouse moved across flat surface.
As balls rotate it touches and turns two rollers inside the mouse
Two rollers are used for vertical and horizontal movements of cursor 19

20. Mouse types Each roller attached to encoder.
Each time a contact bar touches a point an electrical signal.
Signals generated are sent to PC over the mouse cables
And number of mouse time mouse button is clicked.
2. Optical mouse:
When mouse moves the ball of mouse moves and two separate rollers fixed at 90 degree to each other one roller is for vertical and horizontal movement of cursor.
Each roller connected to wheel these rollers are rotated by movement of rollers.
Wheel rotate pair of LED and photo detectors
Signals sent to PC through mouse connectors 20

21. Opto mechnical mouse

22. Mouse types Optical mouse:
LED produces a red light that is emitted onto surface the light reflected back to CMOS sensor then to DSP(digital signal processor) for analysis
DSP analysis the signal and and patterns and determines mouse movements.
Along with coordinates are received by computer and will show mouse movement on screen.

23. Optical mouse

24. Installing Mouse
Locate the mouse port(USB,PS/2 COM1/COM2) on computer system back.
Plug the mouse carefully on the mouse port of computer.
Turn on system.
Installing of mouse driver software
window have built in drivers
Insert driver CD
Run the dialog box displayed on screen.
Fallow installation instruction
Restart computer.