People traditionally used a mechanical trackball equipped wheel mouse to move the cursor about and to point and click on their computer screens earlier. However, with the invention of the latest design of the tiny camera and LED equipped optical mouse in 1999 by Agilent Technologies, the trackball mouse design has been rendered completely obsolete.
Today almost everybody prefers to use the optical mouse because unlike a mechanical trackball mouse, it has no wearing parts. Furthermore, it is not beset by any dirt accumulation issues. It does not even need a mouse pad to work on like its predecessor did.
It uses a tiny camera that takes 1500 pictures every second and a red light-emitting diode (LED) to bounce light off any surface on which the optical mouse rests on. The bounced ray of light is received by a CMOS (complimentary metal-oxide semiconductor) sensor. The sensor passes on every image it receives to a digital signal processor (DSP) for analysis.
The DSP analyses the images at the rate of 18 million instructions per second. It scans each such image for patterns and detects them. It analyses exactly how much change has occurred in the patterns over a sequence of images. Through this device, it is able to assess how much the optical mouse has moved over the surface on which it is moved on.
The DSP then sends the current coordinates of the mouse to the computer as input. The input is then processed within the computer to a certain position on the computer screen. This whole process is repeated hundreds of times per second. The user therefore senses smooth motion of the cursor on the computer screen based on movement of the optical mouse about on the surface it is kept on.
The greatest advantage of the above latest design of the optical mouse over a mechanical trackball mouse is that the chances of its failure are much less. The tracking sensors inside an optical mouse are also bereft of dirt because there is no way the dirt can come in contact with them. Another advantage of an optical mouse is that its tracking resolution is much more enhanced than it is in a trackball mouse.
An older design of optical mouse used a focused light beam to reflect on to a sensor off a high reflection dark gridline equipped mouse pad on which it was kept. The grid caused a break in the light every time the mouse moved across a grid line. This interruption of the light beam was detected by the sensor. The latter then sent a signal to the computer, which then converted the signal to a certain movement of the pointer on the computer screen.
This older design did not become popular for it required you to hold the mouse at precisely the right angle over the mouse pad to ensure alignment of the sensor with the light beam. The mouse pad being a wearing item also required replacement from time to time.
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