Sunday, 26 January 2014




We all know that the keyboard is an input device.
Keyboard has variety of typing key arrangements.
The most widely used as well as commonly used arrangement by us is called DVORAK. It is named after its creator August Dvorak.

Inside the keyboard


Keyboard is like a miniature computer.
It has its own processor and other circuitry necessary for sending information from and to the processor.
The large part of the circuitry contains key matrix.
The key matrix is a grid of circuits.

Working of Keyboard:

Each circuit in the key matrix is open circuited. When a key is pressed, it presses a switch, and the circuit is closed.
A small current flows through the closed circuit.
When the processor identifies that the circuit is closed, it compares the location of the circuit on the key matrix and stores the character in the ROM.
Also the mechanical action of the switch causes small vibration called as bounce.
The bounce is eliminated by processor filters.


Types of switches:

The switches used inside the keyboard is of two types. 1) Mechanical switch 2) Electronic switch

The switch explained in the above passage (working of keyboard) is of mechanical type.
The electronic switch uses capacitor. A small amount of current constantly flows through all the parts of the key matrix.
Each key has a spring load and has a tiny plate at the bottom of it.
When a key is pressed, it moves the plate closer to the plate below it.
As the plates moves closer together, the current flow in the matrix changes.
The processor detects the change and finds the location.

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