From ECDL.web

Operating a mechanical mouse.
1: moving the mouse turns the ball.
2: X and Y rollers grip the ball and transfer movement.
3: Optical encoding disks include light holes.
4: Infrared LEDs shine through the disks.
5: Sensors gather light pulses to convert to X and Y velocities.

In computing, a mouse (plural mice or mouses) 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 computer display. The name mouse, coined at the Stanford Research Institute, derives from the resemblance of early models (which had a cord attached to the rear part of the device, suggesting the idea of a tail) to the common eponymous rodent. The first integrated mouse — shipped as a part of a computer and intended for personal computer navigation — came with Xerox Star in 1981.

[edit] Early mice

Douglas Engelbart of the Stanford Research Institute invented the mouse in 1964 after extensive usability testing. It was one of several experimental pointing-devices developed for Engelbart's oN-Line System (NLS). The other devices exploited other body movements — for example, head-mounted devices attached to the chin or nose — but ultimately the mouse won out because of its simplicity and convenience. The first mouse, a bulky device used two gear-wheels perpendicular to each other: the rotation of each wheel translated into motion along one axis. (See the first public demonstration of the mouse and NLS). Engelbart received patent US3541541 on November 17 1970 for an "X-Y Position Indicator for a Display System". At the time, Engelbart envisaged that users would hold the mouse continuously in one hand and type on a five-key chord keyset with the other.

[edit] Mechanical mice

Early mouse patents. From left to right: Opposing track wheels by Engelbart, Nov. 1970. Ball and wheel by Rider, Sept. 1974. Ball and two rollers with spring by Opocensky, Oct. 1976.

Bill English invented the so-called ball mouse in 1972 while working for Xerox PARC. The ball-mouse replaced the external wheels with a single ball that could 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 resembled an inverted trackball and became the predominant form used with personal computers 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.

Modern computer mice took form at the École Polytechnique Fédérale de Lausanne (EPFL) under the inspiration of Professor Jean-Daniel Nicoud and at the hands of engineer and watchmaker André Guignard. This new design incorporated a single hard rubber mouseball and two buttons, and remained a common design until the mainstream adoption of the scroll-wheel mouse during the 1990s.

[edit] Optical mice

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

Early optical mice, circa 1980, came in two different varieties:

1. Some used an infrared LED and a four-quadrant infrared sensor to detect grid lines printed with infrared absorbing ink on a special metallic surface. Predictive algorithms in the CPU of the mouse calculated the speed and direction over the grid.
2. Others used a 16-pixel visible-light image sensor with integrated motion detection on the same chip and tracked the motion of light dots in a dark field of a printed paper or similar mouse pad.

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".

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.

[edit] Laser mice

Miniature wireless laser mouse with a scroll wheel.

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 resolution of the image taken by the mouse. This led to around 20× more sensitivity to the surface features used for navigation compared to conventional optical mice.

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 (8 seconds after the last motion). This function also increases the laser life. Laser mice designed specifically for gamers appeared later and lack this feature, in an attempt to reduce latency and to improve responsiveness.

[edit] Optical versus mechanical mice

Optical mice have no rolling parts, and therefore (unlike mechanical mice, which can clog up with lint) they do not normally require maintenance other than removing debris that might collect under the light-emitter. However, they generally cannot track on glossy and transparent surfaces, including some mouse-pads, sometimes causing the cursor to drift at random during operation. Mice with less image-processing power also have problems tracking fast movement, though high-end mice can track at 2 m/s (80 inches per second) and faster.

Proponents note that some models of laser mice can track on glossy and transparent surfaces, and have a much higher sensitivity than either their mechanical or optical counterparts. Such models of laser mice cost more than both their LED based counterparts and mechanical mice.

As of 2006, mechanical mice have lower average power demands than their optical counterparts. This typically has no practical impact for users of cabled mice (except possibly those used with battery-powered computers, such as notebook models), but has an impact on battery-powered wireless models. A typical mechanical model requires 0.125 W or less, whereas an optical model draws about 0.5 W (a power ratio of four).

Optical models will outperform mechanical mice on uneven, slick, squishy, sticky or loose surfaces, and generally in mobile situations lacking mouse pads. Since optical mice render movement based on an image which the LED illuminates, use with multi-colored mousepads may result in unreliable performance, however, laser mice do not suffer these problems and will track on such surfaces. The advent of affordable high-speed, low-resolution cameras and the integrated logic in optical mice provides an ideal laboratory for experimentation on next-generation input-devices. Experimenters can obtain low-cost components simply by taking apart a working mouse and changing the optics or by writing new software.

[edit] Buttons

In contrast to the motion-sensing mechanism, the mouse's buttons have changed little over the years, varying mostly in shape, number, and placement. Engelbart's very first mouse had a single button; Xerox PARC soon designed a three-button model, but reduced the count to two for Xerox products. Apple reduced it back to one button with the Macintosh in 1984, while Unix workstations from Sun and others used three buttons. Commercial mice usually have between one and three buttons, although in the late 1990s some mice had five or more.

The two-button mouse has become the most commonly available design. As of 2007 (and roughly since the mid-1990s), users most commonly employ the second button to invoke a contextual menu in the computer's software user interface, which contains options specifically tailored to the interface element over which the mouse pointer currently sits. By default, the primary mouse button sits located on the left-hand side of the mouse, for the benefit of right-handed users; left-handed users can usually reverse this configuration via software. (As of 2007, the most common mice actually have three buttons, with a middle scroll-wheel (see below) that includes a switch function — but they look like and are often referred to as "two-button".)

On systems with three-button mice, pressing the center button (a middle click) often conveniently maps a commonly-used action or a macro. Many users of two-button mice emulate a three-button mouse by clicking both the right and left buttons simultaneously. Middle-clicks often serve as a spare button.

[edit] Additional buttons

Manufacturers have built mice with five or more buttons. Depending on the user's preferences and software environment, the extra buttons may allow forward and backward web-navigation, scrolling through a browser's history, or other functions. As with similar features in keyboards, however, not all software supports these functions. The additional buttons become especially useful in computer games, where quick and easy access to a wide variety of functions can give a player an advantage. Because software can map mouse-buttons to virtually any function, keystroke, application or switch, extra buttons can make working with such a mouse more efficient and easier.

In the matter of the number of buttons, Douglas Engelbart favored the view "as many as possible". The prototype that popularised the idea of three buttons as standard had that number only because "we could not find anywhere to fit any more switches".

[edit] Common button uses

• Single-click
• Select
• Right-select
• Double-click
• Cut
• Paste
• Drag and drop
• Triple-click

[edit] Wheels

The scroll wheel, a notably different form of mouse-button, consists of a small wheel that the user can rotate to provide immediate one-dimensional input. Usually, this input translates into "scrolling" up or down within the active window or GUI-element . The scroll wheel can provide convenience, especially when navigating a long document. The scroll wheel also often includes a pressure detector or switch, a de facto third (center) button. Under many Windows applications, the wheel pressure activates autoscrolling, and in conjunction with the CTRL key may zoom in and out; applications that support this feature include Adobe Reader, Microsoft Word, Internet Explorer, Opera, Mozilla Firefox and others.

Some newer mouse models have two wheels, separately assigned to horizontal and vertical scrolling. Designs exist which make use of a "rocker" button instead of a wheel — a pivoting button that a user can press at the top or bottom, simulating "up" and "down" respectively.

A more recent form of mouse wheel, the tilt-wheel, features in some of the higher-end Logitech and Microsoft mice, such as the Logitech G5. Tilt wheels are essentially conventional mouse wheels that have been modified with a pair of sensors articulated to the tilting mechanism. These sensors are mapped, by default, to horizontal scrolling.

A third variety of built-in scrolling device, the scroll ball, essentially consists of a trackball embedded in the upper surface of the mouse. The user can scroll in all possible directions in very much the same way as with the actual mouse, and in some mice, can use it as a trackball. Mice featuring a scroll ball include Apple's Mighty Mouse and the IOGEAR 4D Web Cruiser Optical Scroll Ball Mouse.

[edit] Connectivity and communication protocols

To transmit their input, typical cabled mice use a thin electrical cord terminating in a standard connector, such as the serial port (RS-232), PS/2, ADB or USB. Cordless mice instead transmit data via infrared radiation or radio (including Bluetooth).

[edit] Tactile mice

In 2000, Logitech introduced the "tactile mouse", which contained a small actuator that made the mouse vibrate. Such a mouse can augment user-interfaces with feedback such as vibrating when crossing a window boundary.

[edit] Accessories

[edit] Mousepad

The mousepad, the most common mouse accessory, appears most commonly in conjunction with mechanical mice, because in order to roll smoothly, the ball requires more friction than common desk surfaces usually provide. Special "hard mousepads" for gamers also exist.

Most optical and laser mice do not require a pad, and using pads with such models remains mostly a matter of personal taste. One exception occurs when the desk surface creates problems for the optical or laser tracking. Other cases may involve keeping desk or table surfaces free of scratches and deterioration; when the grain pattern on the surface causes inaccurate tracking of the pointer, or when the mouse-user desires a more comfortable mousing surface to work on and reduced collection of debris under the mouse.

[edit] Foot covers

Mouse foot covers (or foot pads) consists of low-friction or polished plastic. This makes the mouse glide with less resistance over a surface. Some higher quality models have teflon feet to further decrease friction.

[edit] Wrist-rests

Cushioning pillows made from silicone gel, neoprene or other spongy material have also become popular accessories. The padding provides for a more natural angle of the wrist, in order to reduce fatigue and avoid excessive strain. Others believe that the improved mousing posture is what makes this such a popular accessory.

[edit] Alternative pointing devices

• Trackball – the user rolls a ball mounted in a fixed base.
• Touchpad – detects finger movement about a sensitive surface — the norm for modern laptop computers. At least one physical button normally comes with the touchpad, but users can also (configurably) generate a click by tapping on the pad. Advanced features include detection of finger pressure, and scrolling by moving one's finger along an edge.
• Pointing stick – a pressure sensitive nub used like a joystick on laptops, usually found between the g, h, and b keys on the keyboard.
• Consumer touchscreen devices exist that resemble monitor shields. Framed around the monitor, they use software-calibration to match screen and cursor positions.
• Mini-mouse – a small egg-sized mouse (usually using USB technology) for use with laptop computers — usually small enough for use on a free area of the laptop body itself.
• Graphics Tablet – a tablet with a pen or stylus used for pointing. The user holds the device like a normal pen and moves it across a special pad. The thumb usually controls the clicking via a two-way button on the top of the pen, or by tapping.
• Eyeball-controlled – A mouse controlled by the user's eyeball/retina movements, allowing cursor-manipulation without touch.

[edit] Applications of mice in user interfaces

Usually, computer users utilize a mouse to control the motion of a cursor in two dimensions in a graphical user interface. Clicking or hovering can select files, programs or actions from a list of names, or (in graphical interfaces) through pictures called "icons" and other elements. For example, a text file might be represented by a picture of a paper notebook, and clicking while the pointer hovers this icon might cause a text editing program to open the file in a window.

Users can also employ mice movements; that is, a stylized motion of the mouse cursor itself, called mouse gesture can be used as a form of command and mapped to a specific action. For example, in Opera, right-clicking and moving the mouse to the left is equal to one step back in browsing history.

Gestural interfaces occur more rarely than plain pointing and clicking; and people often find them more difficult to use, because they require finer motor control from the user. However, a few gestural conventions have become widespread, including the drag-and-drop gesture, in which:

1. The user presses the mouse button while the mouse cursor hovers over an interface object
2. The user moves the cursor to a different location while holding the button down
3. The user releases the mouse button

For example, a user might drag and drop a picture representing a file onto a picture of a trash-can, indicating that the file should be deleted.

Other uses of the mouse's input occur commonly in special application-domains. In interactive three-dimensional graphics (like Google Earth), the mouse's motion often translates directly into changes in the virtual camera's orientation. Or, for example, in the first-person shooter genre of games, players usually employ the mouse to control the direction in which the virtual player's "head" faces: moving the mouse up will cause the player to look up, revealing the view above the player's head.

When mice have more than one button, software may assign different functions to each button. Often, the primary button (leftmost in a right-handed configuration) on the mouse will select items, and the secondary button (rightmost in a right-handed configuration) will bring up a menu of alternative actions applicable to that item. For example, on platforms with more than one button, a web browser will follow a link in response to a primary button click (left-click), will bring up a contextual menu of alternative actions for that link in response to a secondary-button click (right-click), and will often open the link in a new tab or window in response to a click with the tertiary (middle) mouse button.