Output device

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An output device is any piece of computer hardware that converts information or data into a human-perceptible form or, historically, into a physical machine-readable form for use with other non-computerized equipment. It can be text, graphics, tactile, audio, or video. Examples include monitors, printers, speakers, headphones, projectors, GPS devices, optical mark readers, and braille readers.

In an industrial setting, output devices also include "printers" for paper tape and punched cards, especially where the tape or cards are subsequently used to control industrial equipment, such as an industrial loom with electrical robotics which is not fully computerized.

Visual

A display device is the most common form of output device which presents output visually on computer screen. The output appears temporarily on the screen and can easily be altered or erased.

With all-in-one PCs, notebook computers, hand held PCs and other devices; the term display screen is used for the display device. The display devices are also used in home entertainment systems, mobile systems, cameras and video game systems.

Display devices form images by illuminating a desired configuration of . Raster display devices are organized in the form of a 2-dimensional matrix with rows and columns. This is done many times within a second, typically 60, 75, 120 or 144Hz on consumer devices.

Interface

The interface between a computer's CPU and the display is a

GPUs can be divided into

A monitor is a standalone display commonly used with a

Older monitors use

Prior to the development of modern pixel-oriented displays,

A projector is a display that projects the computer image onto a surface through the use of a high power lamp. These displays are seen in use to show slideshow presentations or in movie screenings.^[3]

Technologies

Display technologies can be classified based on working principle, lighting (or lack thereof), pixel layout, and more.

Cathode ray tube

(CRT)

CRT screens produce an image using electron tube, which fires electrons at a phosphorous coated screen to light up pixels in order to display images.

Liquid crystal display

(LCD)

An LCD is a display technology employing the use of liquid crystals to form images.

Thin-film transistor

(TFT)

A TFT refers to the thin layer of transistors used with an LCD.

LED-backlit LCD

An LCD display which uses

LEDs as a backlight. Prior to the use of LED based backlighting, Cold Cathode Fluorescent

(CCFL) tubes were used. LED displays use an array of LEDs to form an image.

Electronic paper (e-ink)

An e-ink display uses encapsulated pigment to form an image resembling printed paper, commonly used in

e-book readers

.

Color output

Monochromatic display

A monochrome display is a type of

A speaker is an output device that produces sound through an oscillating transducer called a driver. The equivalent input device is a microphone.

Speakers are plugged into a computer's

The interface between an auditory output device and a computer is the sound card. Sound cards may be included on a computer's motherboard, installed as an expansion card, or as a desktop unit.^[6][7]

The sound card may offer either an analog or

While speakers can be used for any purpose, there are computer speakers which are built for computer use. These speakers are designed to sit on a desk, and as such, cannot be as large as conventional speakers.^[8]

Computer speakers may be powered via USB, and are most often connected through a 3.5mm phone connector.

PC speaker

The PC speaker is a simple loudspeaker built into

Modern computers utilize a piezoelectric buzzer or a small speaker as the PC speaker.

PC speakers are used during Power-on self-test to identify errors during the computer's boot process, without needing a video output device to be present and functional.

Studio monitor

A Studio monitor is a speaker used in a studio environment. These speakers optimize for accuracy.^[9] A monitor produces a flat (linear) frequency response which does not emphasize or de-emphasize of particular frequencies.

Headphones

Headphones, earphones, and earpieces are a kind of speaker which is supported either on the user's head, or the user's ear.

Unlike a speaker, headphones are not meant to be audible to people nearby, which suits them for use in the public, office or other quiet environments.

Technology

Loudspeakers are composed of several components within an enclosure, such as several drivers, active amplifiers, crossovers, and other electronics. Multiple drivers are used to reproduce the full frequency range of human hearing, with tweeters producing high pitches and woofers producing low pitches. Full-range speakers use only one driver to produce as much of a frequency response as possible.^[10]

While

Braille display

Closeup of a refreshable braille display

Braille display in use

A refreshable braille display outputs braille characters through the use of pins raised out of holes on its surface. It is ordinarily used by

Haptic technology involves the use of vibration and other motion to induce a sense of touch.

In mobile devices, Apple added haptic technology in various devices, marketed as 3D Touch and Force Touch. In this form, several devices could sense the amount of force exerted on its touchscreen, while MacBooks could sense two levels of force on its touchpad, which will produce a haptic sensation.^[15]

Printing devices

Printer

A printer is a device that outputs data to be put on a physical item, usually a piece of paper. Printers operate by transferring ink onto this medium in the form of the image received from the host.

Early printers could only print text, but later developments allowed printing of graphics. Modern printers can receive data in multiple forms like vector graphics, as an image, a program written in a page description language, or a string of characters.

Multiple types of printers exist:

Inkjet printers

An inkjet printer injects tiny droplets onto the printing medium via a series of nozzles on a printing head.

Laser printers

A laser printer uses a laser to charge a drum of toner in order to mark points where the toner would stick onto the medium.

Thermal printers

A printer which heats up a thermally sensitive roll of paper to reveal ink. Most often seen in retail stores to print receipts.

Dot matrix printer

A printer which uses

impact

to transfer ink from a ribbon to the medium.

Plotter

A plotter is a type of printer used to print vector graphics. Instead of drawing pixels onto the printing medium, the plotter draws lines, which may be done with a writing implement such as a pencil or pen.^[16]

Teleprinter

A teleprinter or teletypewriter (TTY) is a type of printer that is meant for sending and receiving messages. Before displays were used to display data visually, early computers would only have a teleprinter for use to access the system console. As the operator would enter commands into its keyboard, the teleprinter would output the results onto a piece of paper. The teleprinter would ultimately be succeeded by a computer terminal, which had a display instead of a printer.

Headless operation

A computer can still function without an output device, as is commonly done with servers, where the primary interaction is typically over a data network. A number of protocols exist over serial ports or LAN cables to determine operational status, and to gain control over low-level configuration from a remote location without having a local display device. If the server is configured with a video output, it is often possible to connect a temporary display device for maintenance or administration purposes while the server continues to operate normally; sometimes several servers are multiplexed to a single display device though a KVM switch or equivalent.

Some methods to use remote systems are:

Remote access

The computer's

SSH

.

Remote desktop

Allows a

Graphical User Interface

to be accessed through remote access even without a monitor.

KVM switch

Multiple computers are connected to a single display device which can be switched between computers.

Serial port

A serial console can be connected to access the device's console.

See also

• Input device
• CPU

References

External links

• Media related to Output devices at Wikimedia Commons