Input Devices

In computing, an input device is any peripheral (piece of computer hardware equipment) used to provide data and control signals to an information processing system such as a computer or other information appliance. Input and output devices make up the hardware interface between a computer and a scanner controller.

Many input devices can be classified according to:

• modality of input (e.g. mechanical motion, audio, visual, etc.)
• 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 applications)

Pointing devices, 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 cursor appears. Touchscreens and light pens involve direct input. Examples involving indirect input include the mouse and 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. For example, digitizing graphics tablets 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 where the stylus or puck can be lifted and repositioned.

Keyboards

A 'keyboard' is a 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. Traditional keyboards use spring-based buttons, though newer variations employ virtual keys, or even projected keyboards.

Examples of types of keyboards include:

• Computer keyboard
• Keyer
• Chorded keyboard
• LPFK

Pointing devices

A pointing device is any human interface device that allows a user to input spatial data to a computer. In the case of mice and touch screens, this is usually achieved by detecting movement across a physical surface. Analog devices, such as 3D mice, joysticks, or pointing sticks, function by reporting their angle of deflection. Movements of the pointing device are echoed on the screen by movements of the cursor, creating a simple, intuitive way to navigate a computer's GUI.

High-degree of freedom input devices

Some devices allow many continuous 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 CAVEs, where input that registers 6DOF is required.

Composite devices

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 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.

• Game controller
• Gamepad (or joypad)
• Paddle (game controller)
• Wii Remote

Camera - most cameras like this are used during live conversations.  The camera transmits a picture from one computer to another, or can be used to record a short video.
Compact Disc (CD) - CDs store information.  The CD can then be put into another computer, and the information can be opened and added or used on the second computer. Note:  A CD-R or CD-RW can also be used as an OUTPUT device.
Keyboard - The keyboard is a way to input letters or numbers into different applications or programs.  A keyboard also has special keys that help operate the computer.
Mouse - The mouse is used to open and close files, navigate web sites, and click on a lot of commands (to tell the computer what to do) when using different applications.
Digital Camera - A digital camera can be used to take pictures.  It can be hooked up to a computer to transfer the pictures from the camera to the computer.  Some digital cameras hold a floppy disk, and the floppy disk can be taken out of the camera and put directly into the computer.
Drawing Tablet - A drawing tablet is similar to a white board, except you use a special pen to write on it and it's connected to the computer.  Then the word or image you draw can be saved on the computer.
Microphone - A microphone is used to record sound.  The sound is then saved as a sound file on the computer.
Scanner - A scanner is used to copy pictures or other things and save them as files on the computer.
Disk Drive - A disk drive can hold a CD or a floppy disk.  It reads the information on the disk so that the computer can use it.
Joystick - A joystick is used to move the cursor from place to place, and to click on various items in programs.  A joystick is used mostly for computer games.
Touch Screen - A touch screen is a computer screen or other screen that you can touch with your finger to enter information.  Examples of touch screens include a smart board, a microwave, a dishwasher, or an ATM at a bank.
Bar Code Scanner - A bar code scanner scans a little label that has a bar code on it.  The information is then saved on the computer.  Bar code scanners are used in libraries a lot.