Revision 39111 of "Input device" on shnwiki

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[[File:Typing example.ogv|thumb|A common computer input device, a [[Computer keyboard|keyboard]]. A user presses a key which transfers information to a computer.]]
In [[computing|computing]], an '''input device''' is a [[peripheral|peripheral]] (piece of [[computer hardware|computer hardware]] equipment) used to provide data and control signals to an [[information processing system|information processing system]] such as a [[computer|computer]] or [[information appliance|information appliance]]. Examples of input devices include [[Keyboard (computer)|keyboard]]s, [[Computer mouse|mouse]], [[Image scanner|scanners]], [[digital camera|digital camera]]s and [[joystick|joystick]]s.

Many input devices can be classified according to:
	 
* [[Modality (human–computer interaction)|modality]] of input (e.g. mechanical motion, audio, visual, etc.)
* whether the input is discrete (e.g. key presses) or continuous (e.g. a mouse's position, though digitized into a discrete quantity, is fast enough to be considered continuous)
* the number of degrees of freedom involved (e.g. two-dimensional traditional mice, or three-dimensional navigators designed for [[CAD|CAD]] applications)
	 
[[Pointing device|Pointing device]]s, which are input devices used to specify a position in space, can further be classified according to:
	 
* Whether the input is direct or indirect. With direct input, the input space coincides with the display space, i.e. pointing is done in the space where visual feedback or the [[pointer (computing WIMP)|pointer]] appears. [[Touchscreen|Touchscreen]]s and [[light pen|light pen]]s involve direct input. Examples involving indirect input include the mouse and [[trackball|trackball]].
* Whether the positional information is absolute (e.g. on a touch screen) or relative (e.g. with a mouse that can be lifted and repositioned)
	 
Direct input is almost necessarily absolute, but indirect input may be either absolute or relative.{{clarify|what do these terms mean in this context?|date=November 2012}} For example, digitizing [[graphics tablet|graphics tablet]]s that do not have an embedded screen involve indirect input and sense absolute positions and are often run in an absolute input mode, but they may also be set up to simulate a relative input mode like that of a [[touchpad|touchpad]], where the stylus or puck can be lifted and repositioned.

== Keyboards ==

{{Main|Computer keyboard}}

A 'keyboard' is a [[human interface device|human interface device]] which is represented as a layout of buttons. Each button, or key, can be used to either input a linguistic character to a computer, or to call upon a particular function of the computer. They act as the main [[text entry interface|text entry interface]] for most users. Traditional keyboards use spring-based buttons, though newer variations employ [[Virtual keyboard|virtual keys]], or even [[Projection keyboard|projected keyboards]]. It is typewriter like device composed of a [[Diode matrix|matrix]] of switches.

Examples of types of keyboards include:
* [[Keyer|Keyer]]
* [[Keyboard (computing)|Keyboard]]
* [[LPFK|Lighted Program Function Keyboard (LPFK)]]

== Mouse ==

[[File:Logitech Mouse.JPG|thumb|A [[Mouse (computing)|computer mouse]]]]

Pointing devices are the most commonly used input devices today. A '''pointing device''' is any human interface device that allows a user to input spatial data to a computer. In the case of mouse and touchpads, this is usually achieved by detecting movement across a physical surface. Analog devices, such as [[3D mouse|3D mice]], [[joystick|joystick]]s, or [[pointing stick|pointing stick]]s, function by reporting their angle of deflection. Movements of the pointing device are echoed on the screen by movements of the [[pointer (computing WIMP)|pointer]], creating a simple, intuitive way to navigate a computer's [[Graphic User Interface|graphical user interface (GUI)]].

== High-degree of freedom input devices ==

Some devices allow many continuous [[degrees of freedom|degrees of freedom]] as input. These can be used as pointing devices, but are generally used in ways that don't involve pointing to a location in space, such as the control of a camera angle while in 3D applications. These kinds of devices are typically used in [[Cave Automatic Virtual Environment|virtual reality systems (CAVEs)]], where input that registers [[six degrees of freedom|six degrees of freedom]] is required.

== Composite devices ==

[[File:Wii Remote Image.jpg|thumb|[[Wii Remote|Wii Remote]] with attached strap]]
Input devices, such as buttons and joysticks, can be combined on a single physical device that could be thought of as a composite device.  Many [[video game|gaming]] devices have controllers like this. Technically mice are composite devices, as they both track movement and provide buttons for clicking, but composite devices are generally considered to have more than two different forms of input.

* [[Joystick controller|Joystick controller]]
* [[Gamepad|Gamepad]] (or joypad)
* [[Paddle (game controller)|Paddle (game controller)]] 
* [[Jog dial|Jog dial/shuttle]] (or [[Control knob|knob]])
* [[Wii Remote|Wii Remote]]

== Imaging and input devices ==
[[File:Xbox-360-Kinect-Standalone.png|thumb|Microsoft [[Kinect|Kinect]] sensor, works by detecting human motion visually]]
Video input devices are used to digitize images or video from the outside world into the computer. The information can be stored in a multitude of formats depending on the user's requirement.

* [[Digital camera|Digital camera]]
* [[camcorder|Digital camcorder]]
* [[Portable media player|Portable media player]]
* [[Webcam|Webcam]]
* [[Kinect|Microsoft Kinect Sensor]]
* [[Image scanner|Image scanner]]
* [[Fingerprint scanner|Fingerprint scanner]]
* [[Barcode reader|Barcode reader]]
* [[3D scanner|3D scanner]]
* [[Laser rangefinder|Laser rangefinder]]
* Eye gaze tracker

Medical Imaging
* [[Computed tomography|Computed tomography]]
* [[Magnetic resonance imaging|Magnetic resonance imaging]]
* [[Positron emission tomography|Positron emission tomography]]
* [[Medical ultrasonography|Medical ultrasonography]]

== Audio input devices ==

Audio input devices are used to capture sound. In some cases, an audio output device can be used as an input device, in order to capture produced sound.Audio input devices allow a user to send audio signals to a computer for processing, recording, or carrying out commands. Devices such as microphones allow users to speak to the computer in order to record a voice message or navigate software.Aside from recording, audio input devices are also used with speech recognition software. 

* [[Microphones|Microphones]]
* [[MIDI keyboard|MIDI keyboard]] or other digital musical instrument

== Punched Card devices ==

See [[Punched card input/output]].

== Punched tape devices ==

See [[Punched tape|Punched tape]]

==Other==
* [[Electronic pen|Electronic pen]]
* [[Magnetic ink character recognition|Magnetic ink character recognition]]
*[[Sip-and-puff#Computer_input_device|Sip-and-puff#Computer_input_device]]

==See also==
*[[Peripheral|Peripheral]]
*[[Display device|Display device]]
*[[Output device|Output device]]

==Further reading==
* N. P. Milner. 1988
. [http://portal.acm.org/citation.cfm?id=54675.54695 A review of human performance and preferences with different input devices to computer systems]. In Proceedings of the Fourth Conference of the British Computer Society on People and computers IV, D. M. Jones and R. Winder (Eds.). Cambridge University Press, New York, NY, USA, 341-362. ISBN 0-521-36553-8

{{Basic computer components}}

[[Category:Computing input devices]]
[[Category:Articles containing video clips]]