Wednesday, February 11, 2015

Mechanical mouse

As a mechnical mouse is moved across a flat surface, a ball (made of rubber or rubber covering over a steel ball) from the underside of the mouse starts to rotate in the direction of the movement.
As the ball rotates, it touches and turns two roller touches the ball inside the mouse.
These rollers are mounted at a 90 degree angle to each other.
One roller is used for the back and forth movements of the mouse, which corresponds to vertical movement of the cursor on screen while the other roller is used for horizontal movement of the cursor on the screen.
Each roller is attached to an encoder which is wheel like structure. As the roller turns, these encoders rotate with them.
Two pairs of contact bars touch the small metal contact points provided on the rims of each of these encoders.
Each time a contact bar touches a point, an electrical signal is generated.
The signal generated by the roller are sent serially to the PC over the mouse’s tail like cable.
The mouse driver software converts these signals into the distance, direction and speed necessary to move the screen cursor.
Also pressing of any of the mouse button sends a signal to the PC.