Basics of Mice

By: Mpilchfamily

A mouse functions as a pointing device by detecting two dimensional motion relative to its supporting surface. Physically, a mouse consists of a small case, held under one of the user's hands, with one or more buttons. It sometimes features other elements, such as "wheels", which allow the user to perform various system-dependent operations, or extra buttons or features can add more control or dimensional input. The mouse's motion typically translates into the motion of a pointer on a display.

There are currently three types of mice used today. They are:
  • Mechanical Mice
  • Optical Mice
  • Laser Mice

Optical are the most common mice used today. Mechanical mice have been all but replaced by optical mice. The latest technology is the laser mouse. These mice tend to be more accurate, cost more and are focused at the gaming crowd.

Mechanical Mice

The mechanical mouse or ball-mouse was invented in 1972 by the Xerox PARC group. The ball-mouse uses a single ball that can rotate in any direction and came as part of the hardware package of the Xerox Alto computer. Perpendicular chopper wheels housed inside the mouse's body chopped beams of light on the way to light sensors, thus detecting in their turn the motion of the ball. This variant of the mouse was used with PCs throughout the 1980s and 1990s. The Xerox PARC group also settled on the modern technique of using both hands to type on a full-size keyboard and grabbing the mouse when required.

The ball mouse utilizes two rollers rolling against two sides of the ball. One roller detects the horizontal motion of the mouse and other the vertical motion. The motion of these two rollers causes two disc-like encoder wheels to rotate, interrupting optical beams to generate electrical signals. The mouse sends these signals to the computer system by means of connecting wires. The driver software in the system converts the signals into motion of the mouse pointer along X and Y axes on the screen.

The mechanical mouse had a bad habit of dirt collecting on the ball and internal rollers. This caused the mouse to not function and required regular cleaning. As with all mechanical items they tend to wear out and break much fasted then non-mechanical devices such as the Optical mouse.

Optical Mice

An optical mouse uses a light emitting diode and photo diodes to detect movement relative to the underlying surface, rather than moving some of its parts, as in a mechanical mouse.

As computing power grew cheaper, it became possible to embed more powerful special-purpose image-processing chips in the mouse itself. This advance enabled the mouse to detect relative motion on a wide variety of surfaces, translating the movement of the mouse into the movement of the pointer and eliminating the need for a special mouse-pad. This advance paved the way for widespread adoption of optical mice.

Modern surface-independent optical mice work by using an optoelectronic sensor to take successive pictures of the surface on which the mouse operates. Most of these mice use LEDs to illuminate the surface that is being tracked; LED optical mice are often mislabeled as "laser mice". Changes between one frame and the next are processed by the image processing part of the chip and translated into movement on the two axes using an optical flow estimation algorithm. For example, the Agilent Technologies ADNS-2610 optical mouse sensor processes 1512 frames per second: each frame is a rectangular array of 18×18 pixels, and each pixel can sense 64 different levels of gray.

Optomechanical mice detect movements of the ball optically, giving the precision of optical without the surface compatibility problems, whereas optical mice detect movement relative to the surface by examining the light reflected off it.

Laser Mice

As early as 1998, Sun Microsystems provided a laser mouse with their Sun SPARCstation servers and workstations. However, laser mice did not enter the mainstream market until 2004, when Logitech, in partnership with Agilent Technologies, introduced the laser mouse with its MX 1000 model. This mouse uses a small infrared laser instead of an LED, which increases the image resolution taken by the mouse. This leads to around 20× more sensitivity to the surface features used for navigation compared to conventional optical mice, via interferance effects.

Engineers designed the laser mouse — as a wireless mouse — to save as much power as possible. In order to do this, the mouse blinks the laser when in standby mode. This function also increases the laser life. Laser mice designed specifically for gamers, such as the Logitech G5, appeared later and lack this feature, in an attempt to reduce latency and to improve responsiveness.

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