History Of What Are Output Devices

Published Date: 02 Nov 2017

An output device is any piece of computer hardware component which is used in order to communicate with the results of data processing that has carried out by an information processing system for example a computer which converts an electronically generated information into the human-readable form.

Display devices

A display device is an output device which visually conveys the text or graphics or even video information. The Information which is shown on a display device is known as soft copy because the information resides electronically and is being displayed for a short period of time. Display devices for exampleCRT monitors, , gas plasma monitors, LCD monitors and displays and televisions.

Input/output

CPT Hardware-InputOutput

Inputs are the signals or data received by the system, and outputs are the signals or data sent from it.

There are several input and output devices for example multifunction printers and computer-based navigation systems which are used for specialised as well as unique applications. In computing, input/output, or I/O which refers to the communication in between an information processing system for example a computer and the outside the world. Inputs are basically signals or data received by the system and on the other hand outputs are the signals or data which is sent from it.

Types of output

Some types of output are audio, video, text, graphics tactile etc. Text generally consists of characters letters for examplenumbers, punctuation marks, or many other symbols, requiring one byte of computer storage space which are used in order to create words, sentences, and paragraphs. Graphics are the digital representations of the non text information for example photographs, drawings, charts and animation. Tactile output for example raised line drawings may be useful for some individuals who are blind. Audio is generally music, speech, or any other sound. Video which consists of images played back at speeds to provide the appearance of full motion.

Graphics

Tactile

Audio

Graphics

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Graphical output displayed on a screen.

A digital image is a numeric representation of a particular image stored on a computer. They don't have any physical size until they are displayed on the monitor screen or printed on the paper. Actually they are mainly a collection of numbers on the hard drive of the computer which describe the individual elements of a particular picture and how they are being arranged. Some of the computers come built with graphics capability. Others shouldneed a device, which is known as a graphics card or graphics adapter board which has to be added. If not a computer has graphics capability built into the motherboard which has translation that takes place on the graphics card. Depending on whether the image resolution is constant it may be of vector or raster type. Without qualifications, the term digital image generally refers to raster images which is also called bitmap images. Raster images which are composed of pixels and is suitable for photo-realistic images. Vector images which are composed of the lines and co-ordinates rather than dots and that is more suited to line art, graphs or fonts. To make a 3-D image, the graphics card first creates a wire frame out of straight lines. Then, it rasterizes the image. It also adds lighting, texture and color.

Tactile

Haptic technology, or haptics, is a tactile feedback technology which takes the advantages of the sense of touch by applying different resources for exampleforces, vibrations, or motions to the user. Many printers for examplewax jet printers have the capabilities of producing raised line drawings. There are also other handheld devices that may use an array of vibrating pins in order to present a tactile outline of the characters or the text under the viewing window of the device.

Audio

Speech output systems which is can be used to read screen text for the computer users. Special software programs which is known as screen readers attempt in order to identify and interpret what is being displayed on the monitor screen and the speech synthesizers generally convert data to vocalized sounds or text.

What are monitors ? Discuss various types of computer monitors.

A monitor or a display also called screen or visual display unit is an electronic visual display for computers. The monitor which comprises the display device, circuitry and an enclosure. The display device in modern monitors is generally a thin film transistor liquid crystal display (TFT-LCD) thin panel, while on the other hand older monitors are using a cathode ray tube (CRT) about as deep as the screen size.

initially, computer monitors were used for data processing on the other hand television receivers were used mainly for entertainment. At the time of 1980s onwards, computers and their monitors have been used for both data processing as well as entertainment, while televisions had implemented some computer functionalities. The common aspect ratio of televisions, and computer monitors, has also changed from 4:3 to 16:9.

Technologies used in monitors

Multiple technologies have been used in the computer monitors. By 21st century most of the monitors used cathode ray tubes but they have largely been replaced by LCD monitors.

Cathode ray tube

Liquid crystal

Organic light-emitting diode

Cathode ray tube

The first computer monitors used Cathode Ray Tubes or CRT. By 1980s, they were known as video display terminals and physically attached to the computer or keyboard. These monitors were flickered, monochrome and the image quality was poor. In 1981, IBM has introduced the Color Graphics Adapter which could display four main colors with a resolution of 320 by 200 pixels. In 1984 they introduced the Enhanced Graphics Adapter which was capable for producing 16 colors and had a resolution of 640 by 350 pixels.

CRT technology remained dominant in the PC monitor market into the new millennium partly because it was cheaper to produce and offered viewing angles close to 180 degrees.

Liquid crystal

There are multiple technologies which have been used in order to implement Liquid Crystal Displays or LCD. Up to 1990s, the main use of LCD technology as computer monitors was in laptops where the lower power consumption, lighter weight, and smaller physical size of LCDs justified the higher price versus a CRT. Commonly, the same laptop would be offered with an assortment of display options at increasing price points: (active or passive) monochrome, passive color, or active matrix color (TFT). As volume and manufacturing capability have improved, the monochrome and passive color technologies were dropped from most product lines.

TFT-LCD is a variant of LCD which is now the dominant technology used for computer monitors.[3]

The first standalone LCD displays appeared in the mid-1990s selling for high prices. As prices declined over a period of years they became more popular, and by 1997 were competing with CRT monitors. Among the first desktop LCD computer monitors was the Eizo L66 in the mid-1990s, the Apple Studio Display in 1998, and the Apple Cinema Display in 1999. In 2003, TFT-LCDs outsold CRTs for the first time, becoming the primary technology used for computer monitors. The main advantages of LCDs over CRT displays are that LCDs consume less power, take up much less space, and are considerably lighter. The now common active matrix TFT-LCD technology also has less flickering than CRTs, which reduces eye strain. On the other hand, CRT monitors have superior contrast, have superior response time, are able to use multiple screen resolutions natively, and there is no discernible flicker if the refresh rate is set to a sufficiently high value. LCD monitors have now very high temporal accuracy and can be used for vision research.

Organic light-emitting diode

Organic light-emitting diode (OLED) monitors provide higher contrast and better viewing angles than LCDs, and are predicted to replace them. In 2011, a 25-inch OLED monitor cost $7500, but the prices are expected to drop.

What are speakers?

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 3.5 mm (approximately 1/8 inch) stereo phone connector often color-coded lime green (following the PC 99 standard) for computer sound cards. A few use an RCA connector for input. There are also USB speakers which are powered from the 5 volts at 500 milliamps provided by the USB port, allowing about 2.5 watts of output power.

Computer speakers range widely in quality and in price. The computer speakers typically packaged with computer systems are small, plastic, and have mediocre sound quality. Some computer speakers have equalization features for example bass and treble controls.

The internal amplifiers require an external power source, usually an AC adapter. 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. Restricted space available in laptops means these speakers usually 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.

What are headphones? What are their applications?

Headphones are a pair of small loudspeakers which are designed in order to be held in place close to a user's ears. Headphones are either have wires for connection to a signal source for example an audio amplifier, portable media player, radio, CD player, or mobile phone, or have any wireless receiver, which is used to pick up signal without using any cable lines . They are generally known as earspeakers or cans. The in-ear versions are also known as earphones or earbuds. In the context of telecommunication, a headset is a grouping of headphone and microphone such as

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Brandes radio headphones, circa 1920.

Headphones started from the earpiece, and were only way in order to listen to electrical audio signals before amplifiers were developed. The first successful set was developed by Nathaniel Baldwin, who has made them by his hand in his kitchen and sold them to the United States Navy.

Very sensitive headphones for example those, which are manufactured by Brandes in 1919 were commonly used for early radio works. These y headphones were generally used moving iron drivers, either single ended or balanced armature. The requirement for high sensitivity meant that no damping were used, therefore the sound quality was rough. They also had very poor ease as compared to modern types which is usually having no padding and too often having unnecessary clamping force to the head. Their impedance generally varied; headphones used in telegraph as well as telephone work had an impedance of approximately 75 ohms. Those were used with early wireless radio had to be more responsive and were made up of more thinner wire; impedance of 1,000 to 2,000 ohms was common, which suited both crystal sets and triode receivers.

In earlier powered radios, the headphone was a part of the vacuum tube's plate circuit which had dangerous voltages on it. It was normally connected directly to the positive high voltage battery port and the other battery terminal was strongly grounded. The use of bare electrical connections meant that users could be shocked if they touched the bare headphone connections while adjusting an uncomfortable headset.

Applications

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Sennheiser HD555 headphones, used in audio production environments (2007)

Headphones may be used both with fixed equipment for example CD or DVD players, , personal computers, home theater and with portable devices such as digital audio player/mp3 player, mobile phone. Cordless headphones are generally not connected through a wire, receiving a radio or infrared signal encoded using infrared transmission link or a radio like FM, Bluetooth or Wi-Fi. These are called powered receiver systems of which the headphone is only a component. Cordless headphones are mainly used with events for example a Silent disco or Silent Gig.

In the professional audio sector headphones which are used in the live situations by disc jockeys with a DJ mixer and sound engineers for monitoring the signal sources. In the case of radio studios, DJs use a pair of headphones at the time of talking to the microphone on the other hand the speakers are turned off in order to eliminate acoustic feedback and monitor its own voice. In studio recordings, musicians and singers generally use headphones in order to play along to a backing track. Also in the military, audio signals of many varieties are monitored using headphones.

Wired headphones are generally attached to an audio source. The most common connectors are 3.5mm and 6.35mm (¼″) phone connectors. The larger one i.e. 6.35mm connector tends to be found on the fixed location home or may be on professional equipment. Sony has introduced the smaller, and now they are widely used, 3.5mm "minijack" stereo connector. In the year 1979, adapting the older monophonic 3.5mm connector for the use with its Walkman portable stereo tape player. The 3.5mm connector what's left the common connector for portable application today. Adapters are also available for converting between 6.35mm and 3.5mm devices.

What are different types of headphones?

The particular needs of the listener decide the choice of headphone. The need for portability refers to the smaller, lighter headphones, but it can mean a cooperation in faithfulness. Headphones generally used as part of a home hi-fi that do not have the same design constraints and can be larger and bulky. Generally, these headphone form factors can be divided into four different categories such as:

Circumaural

Supra-aural

Open or closed back

Ear-fitting headphones

Headset

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Circumaural headphones have large pads that surround the outer ear.

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A pair of supra-aural headphones.

Circumaural

Circumaural headphones also known as full size headphones have circular or ellipsoid earpads that encompass the ears. Because these headphones are completely surround the ears, 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 that weigh over 500 grams. Ergonomic headband and earpad design is required to reduce discomfort resulting from weight.

Supra-aural

Supra-aural headphones have pads which is used to press against the ears, rather than around them. They were normally tied up together with personal stereos in the year 1980s. This type of headphone usually tends to be smaller and lighter than other headphones which resulting in less attenuation of outside noise.

Open or closed back

The headphones i.e. circumaural and supra-aural headphones can be divided by the type of earcups i.e.:

Open-back are headphones that have the back of the earcups open. This leaks more sound out of the headphone and also they are more ambient sounds into the particular headphone, but it gives a more natural or alike speaker sound and more spacious that is the observation of distance from the source to the destination.

Closed-back known as sealed styles which have the back of the earcups closed. Depending on the different model they can block 8-32db of ambient noise, but they have a smaller soundscape, giving the wearer concept from which the sound is coming through their head. One reason for this is that there are sounds reflected back towards the ear.

Ear-fitting headphones

[edit] Earbuds

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Earbuds/earphones sit in the outer ear

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In-ear monitors extend into the ear canal, providing isolation from outside noise.

Earbuds and earphones which are refer to very small headphones that can be fitted directly in the outer ear but may not be inserted in the ear canal. They don’t have band or other arrangement in order to fit over the head. However, many other consumer-quality in-ear-canal systems are also called earbuds by their manufacturers. The outer-ear earphones are generally portable as well as convenient, but most of the people consider them to be not comfortable and tends to falling out. Different models are available, which are starting at very low prices. They provide hardly any sound loneliness and leave the room for ambient noise to seep in. Users may turn up the volume seriously high to compensate, at the risk of causing hearing loss. On the other hand, they let the user to be better awared of their surroundings. Since earlier of the transistor radio, earbuds have commonly been bundled with personal music devices. They have been sold at times with foam pads for comfort.

In-ear headphones

In-ear headphones, like earbuds, are small and without headband, but they are inserted in the ear canal themselves. They are also known as canalphones. Price and quality ranges from relatively inexpensive to extremely high. But the better ones that are called in-ear monitors (IEMs) and they are used by audio engineers and musicians as well as audiophiles.

Canalphones generally offer portability similar to the earbuds which can block out much environmental noise by obstructing the ear canals, and are far less tentds to be falled. When they used as casual portable use they usually block out sounds which can be important for safety reasons.

Headset

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A typical example of a headset used for voice chats.

A headset is a headphone joint with a microphone. Headsets mainly provide the equivalent functionalities of a telephone handset along with hands-free operation. Among several applications for headsets, besides telephone use, are aviation, theatre or television studio intercom systems, and console or PC gaming. Headsets can be made with either a single-earpiece (mono) or a double-earpiece for example mono to both ears or stereo. The microphone arm of headsets may be either an external microphone type where the microphone is held in front of the user's mouth, orit may be voice tube type where the microphone generally housed in the earpiece and speech reaches it through a hollow tube. Some headsets come in a choice of either behind-the-neck or no-headband design instead of the traditional over-the-head band.

Telephone headsets

Telephone headsets usually connect to a fixed-line telephone system. A telephone headset generally functions by replacing the handset of a telephone. These Headsets for standard corded telephones which are fitted with a standard 4P4C also called an RJ-9 connector. Headsets are mainly available in the market.with 2.5mm jack sockets for many DECT phones and other communication applications. Cordless bluetooth headsets are available, and they are often used with mobile telephones. Headsets are broadly used for telephone-intensive jobs, mainly for call centre workers. They are also used by anyone wishing in order to hold telephone conversations with both hands free.

For earlier telephones, the headset microphone impedance was different from that of the original handset which is 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 switching between headset and handset. Telephone amplifiers are powered by batteries or AC adaptors.