Computer Mouse

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Computer Mouse The Computer Mouse The computer mouse first came about in the early 1980's. The idea being that the movement from the users hand could be turned into signals that the computer could read moving the cursor around and also allowing the buttons to function when pressed. Today there are a few different types of computer mice on the market. These being the mice that use the traditional tracking ball, the optical mouse and the mouse that has no physical connection to the computer. The most common mouse found near a computer today is the traditional mouse that uses the tracking ball. This is the same method as was used when the mouse was first released in the 1980's. The track ball inside the mouse touches the desk when it is moved. When the ball moves the motion is detected by two perpendicular axis, one which detects x axis directional motion and the other y-axis direction motion. Tracking Ball Perpendicular axis motion detectors Hole in which track ball would sit The diagrams above show the tracking ball and the hole in which the tracking ball sits. You can see the x and y axis motion detectors of which the y-axis detector lies 90° from the x-axis detector. These motion detectors are also known as rollers. When the mouse is in use the tracking ball moves moving one or both of the rollers. Each roller is connected to a shaft, which spins a disc. The disc has holes in it and next to the disc is an infrared LED and an infrared sensor. As the disc spins the hole in the disc breaks the beams of light generated by the LED and the sensor picks up these pulses of light. The speed of the pulses is related to how far the mouse has travelled. If the disc spins faster the further the mouse would have travelled. A diagram below shows one of these discs. LED light LED sensor Disc Shaft So from the mouse which is mechanical the movement and distance can be measured. This all starts at the track ball as explain above and ends at the transducers, which send the information to the computer. Once the distance, movement and direction data is gathered from the physical and the pulses of light are picked up from the infrared sensor the information is sent to the transducers. These transducers translate the information into electrical signals. These signals are translated into binary and sent to the computer. The computer will understand the binary data thus moving the cursor on the screen as appropriate. This shows that both physical and electrical operations

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