An Output Device Is Any Piece of Computer Hardware Equipment
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An output device is any piece of computer hardware equipment used to communicate the results of data processing carried out by an information processing system (such as a computer) to the outside world. In computing, input/output, or I/O, refers to the communication between an information processing system (such as a computer), and the outside world. Inputs are the signals or data sent to the system, and outputs are the signals or data sent by the system to the outside. Examples of output devices: • Speaker • Headphones • Screen (Monitor) • Printer Computer speakers, or multimedia speakers, are speakers external to a computer, that disable the lower fidelity built-in speaker. They often have a low-power internal amplifier. The standard audio connection is a 3.175mm (1/8 inch) stereo jack plug often colour-coded lime green (following the PC 99 standard) for computer sound cards. A plug and socket for a two-wire (signal and ground) coaxial cable that is widely used to connect analog audio and video components. Also called a "phono connector," rows of RCA sockets are found on the backs of stereo amplifier and numerous A/V products. The prong is 1/8" thick by 5/16" long. A few use an RCA connector for input. There are also USB speakers which are powered from the 5 volts at 200 milliamps provided by the USB port, allowing about half a watt of output power. Computer speakers range widely in quality and in price. The computer speakers typically packaged with computer systems are small plastic boxes with mediocre sound quality. Some of the slightly better computer speakers have equalization features such as bass and treble controls, improving their sound quality somewhat. The internal amplifiers require an external power source, known as a 'wall-wart'. More sophisticated computer speakers can have a 'subwoofer' unit, to enhance bass output, and these units usually include the power amplifiers both for the bass speaker, and the small 'satellite' speakers. Some computer displays have rather basic speakers built-in. Laptops come with integrated speakers. Unfortunately the tight restriction on space inevitable in laptops means these speakers unavoidably produce low-quality sound. For some users, a lead connecting computer sound output to an existing stereo system is practical. This normally yields much better results than small low-cost computer speakers. Computer speakers can also serve as an economy amplifier for MP3 player use for those who wish to not use headphones although some models of computer speakers have headphone jacks of their own. Headphones are a pair of small loudspeakers, or less commonly a single speaker, with a way of holding them close to a user's ears and a means of connecting them to a signal source such as an audio amplifier, radio or CD player. They are also known as stereophones, headsets or, colloquially cans. The in-ear versions are known as earphones or earbuds. In the context of telecommunication, the term headset is used to describe a combination of headphone and microphone used for two-way communication, for example with a telephone Types of headphones The particular needs of the listener determine the choice of headphone. The need for portability indicates smaller, lighter headphones but can mean a compromise in fidelity. Headphones used as part of a home hi-fi do not have the same design constraints and can be larger and heavier. Generally, headphone form factors can be divided into four separate categories: circumaural, supra-aural, earbud, and in-ear. [edit] Circumaural Circumaural headphones have large pads that surround the outer ear. Circumaural headphones (sometimes called full size headphones) have circular or ellipsoid earpads that encompass the ears. Because these headphones completely surround the ear, circumaural headphones can be designed to fully seal against the head to attenuate any intrusive external noise. Because of their size, circumaural headphones can be heavy and there are some sets which weigh over 500 grams. Good headband and earpad design is required to reduce discomfort resulting from weight. [edit] Supra-aural A pair of supra-aural headphones. Supra-aural headphones have pads that sit on top of the ears, rather than around them. They were commonly bundled with personal stereos during the 1980s. This type of headphone generally tends to be smaller and more lightweight than circumaural headphones, resulting in less attenuation of outside noise. [edit] In-ear headphones [edit] Earbuds Earbuds / earphones Earbuds or earphones are headphones of a much smaller size that are placed directly outside of the ear canal, but without fully enveloping it. They are generally inexpensive and are favored for their portability and convenience. Due to their inability to provide any isolation they are often used at higher volumes in order to drown out noise from the user's surroundings, which increases the risk of hearing- loss.[2] During the 1990s and 2000s, earbuds became a common type bundled with personal music devices. [edit] Canalphones Main article: In-ear monitor Canalphones extend into the ear canal, providing isolation from outside noise. Canalphones (also known as in-ear monitors, or IEMs) are earphones that are inserted directly into the ear canal. Canalphones offer portability similar to earbuds, and also act as earplugs to block out environmental noise. There are two main types of IEMs: universal and custom. Universal canalphones provide one or more stock sleeve size(s) to fit various ear canals, which are commonly made out of silicone rubber, elastomer, or foam, for noise isolation. Custom canalphones are fitted to the ears of each individual. Castings of the ear canals are made and the manufacturer uses the castings to create custom-molded silicone rubber or elastomer plugs that provide added comfort and noise isolation. Because of the individualized labor involved, custom IEMs are more expensive than universal IEMs and resell value is very low as they are unlikely to fit other people. [edit] Headset Main article: Headset (telephone/computer) A typical example of a headset used for voice chats. A headset is a headphone combined with a microphone. Headsets provide the equivalent functionality of a telephone handset with hands-free operation. The most common uses for headsets are in console or PC gaming, Call centres and other telephone-intensive jobs and also for personal use at the computer to facilitate comfortable simultaneous conversation and typing. Headsets are made with either a single- earpiece (mono) or a double-earpiece (mono to both ears or stereo). The microphone arm of headsets is either an external microphone type where the microphone is held in front of the user's mouth, or a voicetube type where the microphone is housed in the earpiece and speech reaches it by means of a hollow tube. [edit] Telephone headsets Telephone headsets connect to a fixed-line telephone system. A telephone headset functions by replacing the handset of a telephone. All telephone headsets come in a standard 4P4C commonly called an RJ-9 connector. For older models of telephones, the headset microphone impedance is different from that of the original handset, requiring a telephone amplifier for the telephone headset. A telephone amplifier provides basic pin-alignment similar to a telephone headset adaptor, but it also offers sound amplification for the microphone as well as the loudspeakers. Most models of telephone amplifiers offer volume control for loudspeaker as well as microphone, mute function and headset/handset switching. Telephone amplifiers are powered by batteries or AC adaptors. A monitor or display (sometimes called a visual display unit) is an electronic visual display for computers. The monitor comprises the display device, circuitry, and an enclosure. The display device in modern monitors is typically a thin film transistor liquid crystal display (TFT-LCD), while older monitors use a cathode ray tube (CRT). Comparison [edit] CRT Pros: • High dynamic range (up to around 15,000:1 [1],) excellent color, wide gamut and low black level. • Can display natively in almost any resolution and refresh rate • No input lag • Sub-millisecond response times • Near zero color, saturation, contrast or brightness distortion. Excellent viewing angle. • Usually much cheaper than LCD or Plasma screens. Cons: • Large size and weight, especially for bigger screens (a 20-inch unit weighs about 50 lb (23 kg)) • High power consumption • Geometric distortion caused by variable beam travel distances • Older CRTs are prone to screen burn-in • Produces noticeable flicker at low refresh rates [edit] LCD Pros: • Very compact and light • Low power consumption • No geometric distortion • Rugged • Little or no flicker depending on backlight technology Cons: • Limited viewing angle, causing color, saturation, contrast and brightness to vary, even within the intended viewing angle, by variations in posture. • Bleeding and uneven backlighting in some monitors, causing brightness distortion, especially toward the edges. • Slow response times, which cause smearing and ghosting artifacts. Modern LCDs have response times of 8 ms or less. • Only one native resolution. Displaying resolutions either requires a video scaler, lowering perceptual quality, or display at 1:1 pixel mapping, in which images will be physically too large or won't fill the whole screen. • Fixed bit depth, many cheaper LCDs are incapable of truecolor. • Input lag • Dead pixels may occur either during manufacturing or through use. [edit] Plasma Main article: Plasma display Pros: • Compact and light. • High contrast ratios (10,000:1 or greater,) excellent color, wide gamut and low black level. • High speed response. • Near zero color, saturation, contrast or brightness distortion. Excellent viewing angle. • No geometric distortion. • Highly scalable, with less weight gain per increase in size (from less than 30 in (760 mm) wide to the world's largest at 150 in (3,800 mm)). Cons: • Large pixel pitch, meaning either low resolution or a large screen.