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Joined: Dec 2008
21-09-2008, 11:08 AM
An optical mouse is an advanced computer pointing device that uses a light-emitting diode (LED), an optical sensor, and digital signal processing (DSP) in place of the traditional mouse ball and electromechanical transducer. Movement is detected by sensing changes in reflected light, rather than by interpreting the motion of a rolling sphere.
The optical mouse takes microscopic snapshots of the working surface at a rate of more than 1,000 images per second. If the mouse is moved, the image changes. The tiniest irregularities in the surface can produce images good enough for the sensor and DSP to generate usable movement data. The best surfaces reflect but scatter light; an example is a blank sheet of white drawing paper. Some surfaces do not allow the sensor and DSP to function properly because the irregularities are too small to be detected. An example of a poor optical-mousing surface is unfrosted glass.
In practice, an optical mouse does not need cleaning, because it has no moving parts. This all-electronic feature also eliminates mechanical fatigue and failure. If the device is used with the proper surface, sensing is more precise than is possible with any pointing device using the old electromechanical design. This is an asset in graphics applications, and it makes computer operation easier in general.
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Joined: Feb 2012
21-03-2012, 10:06 AM
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Joined: Apr 2012
22-09-2012, 01:48 PM
1OPTICAL MOUSE.pdf (Size: 251.64 KB / Downloads: 52)
Every day of our computing life, we reach out for our mouse whenever we want to move our cursor or
activate something. Our mouse senses our motion and our clicks and sends them to the computer so
that it can respond appropriately. It is amazing how simple and effective a mouse is, and it
is also amazing how long it took Mice to become a part of everyday life. Given that people
naturally point at things -- usually before they speak -- it is surprising that it took so long for a
good pointing device to develop. Although originally conceived in the 1960s, it took quite
some time for mice to become mainstream. In the beginning there was no need to point because
computers used crude interfaces like teletype machines or punch cards for data entry. The early text
terminals did nothing more than emulate a teletype (using the screen to replace paper), so it was many
years (well into the 1960s and early 1970s) before arrow keys were found on most terminals. Full
screen editors were the first things to take real advantage of the cursor keys, and they offered humans
the first crude way to point.
Optical Technology uses an optical sensor to track movement, rather than the standard ball and
moving parts. Optical Technology provides increased control and precision and works on most
surfaces. This superior technology translates into precise cursor movement and unmatched
It is amazing how simple and effective a mouse is, and it is also amazing how long it took mice to
become a part of everyday life. Given that people naturally point at things -- usually before they
speak -- it is surprising that it took so long for a good pointing device to develop. Although
originally conceived in the 1960s, it took quite some time for mice to become mainstream.
In the beginning there was no need to point because computers used crude interfaces like
Teletype machines or punch cards for data entry before arrow keys were found on most terminals.
Full screen editors were the first things to take real advantage of the cursor keys, and they offered
humans the first crude way to point.
Light pens were used on a variety of machines, as a pointing device for many years, and graphics
tablets, joysticks and various other devices were also popular in the 1970s. None of these really
took off as the pointing device of choice, however, when the mouse hit the scene, it was an
immediate success. There is something about it that is completely natural. Compared to a
graphics tablet, mice are extremely inexpensive and they take up very little desk space. In the PC
world, mice took longer to gain ground, mainly because of a lack of support in the Operating
system. Once Windows 3.1 made Graphical User Interfaces (GUIs) a standard, the mouse became
the PC-human interface of choice very quickly.
HOW DO THEY WORK?
Open up a mouse and inside it we will find two wheels, each one similar to the first drawing. The
wheel is usually made of black plastic with rectangular slots punched in it. I have shown only 6
slots at 60° spacing but they are a lot closer and many more. Shining through the slots are two
LEDs (light Emitting Diodes) shown by the black dots. Each LED shines on to a light sensitive
transistor. The two emitters are spaced so that, when one transistor can 'see' its LED through the
centre of its window, the other LED is looking at an edge and is therefore switching on or off. In
my illustration the LEDs are spaced at 105° (60° x 1.75). The output voltage from the transistor is
processed to switch rapidly from high to low as the LED's light is transmitted or occluded so that
the voltage is low when the transistor is lit and high when it is in darkness. In the diagram LED A
is fully illuminated and LED B is switching. Note that LED B may be switching from light to
dark or from dark to light - this depends on the rotation direction.