OUTPUT DEVICES

OUTPUT DEVICES

 VDU:

 The computer screen is used for outputting information in an understandable format. In short  Visual Display Unit, VDU is an older British term used to describe any device used with computers to display images. For example, a flat panel display and a projector are both examples of VDUs. However, VDU is most commonly used to describe the CRT monitor, a now archaic standard that has been replaced by flat panel displays.

 Another Defination: Video Display Unit, VDU is a computing device that allows for input by a user and output to a display, like a computer monitor. It typically consists of a computer monitor or similar display device and a keyboard, and could also include a mouse. In the United States, it is sometimes referred to as a video display terminal, or VDT.

Printers:

 There are many different types of printers.   In large organizations laser printers are most commonly used due to the fact that they can print very fast and give a very high quality output.

Another defination: A printer is any device that prints text or illustrations on paper. There are many different types of printers. A hammer presses the wheel against a ribbon, which in turn makes an ink stain in the shape of the character on the paper.

Daisy-wheelprinters produce letter-quality print but cannot print graphics.

 Plotters:

 A plotter is an output device similar to a printer, but normally allows you to print larger images.

Another Defination: 

A plotter is a printer designed for printing vector graphics. Instead of printing individual dots on the paper, plotters draw continuous lines. This makesplotters ideal for printing architectural blueprints, engineering designs, and other CAD drawings.

 There are two main types of plotters. These are as follows:

1. Drum Plotter.

2. Flatbed Plotter.

 Speakers:

 Enhances the value of educational and presentation products.

 Speakers are one of the most common output devices used with computer systems. Some speakers are designed to work specifically with computers, while others can be hooked up to any type of sound system. Regardless of their design, the purpose of speakers is to produce audio output that can be heard by the listener.

Speakers are transducers that convert electromagnetic waves into sound waves. The speakers receive audio input from a device such as a computer or an audio receiver. This input may be either in analog or digital form. Analog speakers simply amplify the analog electromagnetic waves into sound waves. Since sound waves are produced in analog form, digital speakers must first convert the digital input to an analog signal, then generate the sound waves.

The sound produced by speakers is defined by frequency and amplitude. The frequency determines how high or low the pitch of the sound is. For example, a soprano singer's voice produces high frequency sound waves, while a bass guitar or kick drum generates sounds in the low frequency range. A speaker system's ability to accurately reproduce sound frequencies is a good indicator of how clear the audio will be. Many speakers include multiple speaker cones for different frequency ranges, which helps produce more accurate sounds for each range. Two-way speakers typically have a tweeter and a mid-range speaker, while three-way speakers have a tweeter, mid-range speaker, and subwoofer.

Amplitude, or loudness, is determined by the change in air pressure created by the speakers' sound waves. Therefore, when you crank up your speakers, you are actually increasing the air pressure of the sound waves they produce. Since the signal produced by some audio sources is not very high (like a computer's sound card), it may need to be amplified by the speakers. Therefore, most external computer speakers are amplified, meaning they use electricity to amplify the signal. Speakers that can amplify the sound input are often called active speakers. You can usually tell if a speaker is active if it has a volume control or can be plugged into an electrical outlet. Speakers that don't have any internal amplification are called passive speakers. Since these speakers don't amplify the audio signal, they require a high level of audio input, which may be produced by an audio amplifier.

Speakers typically come in pairs, which allows them to produce stereo sound. This means the left and right speakers transmit audio on two completely separate channels. By using two speakers, music sounds much more natural since our ears are used to hearing sounds from the left and right at the same time. Surround systems may include four to seven speakers (plus a subwoofer), which creates an even more realistic experience.

Speech synthesisers:

 Gives you the ability to not only to display text on a monitor but also to read the text

to you.

Speech synthesis is the computer-generated simulation of human speech. It is used to translate written information into aural information where it is more convenient, especially for mobile applications such as voice-enabled e-mail and unified messaging . It is also used to assist the vision-impaired so that, for example, the contents of a display screen can be automatically read aloud to a blind user. Speech synthesis is the counterpart of speech or voice recognition . The earliest speech synthesis effort was in 1779 when Russian Professor Christian Kratzenstein created an apparatus based on the human vocal tract to demonstrate the physiological differences involved in the production of five long vowel sounds. The first fully functional voice synthesizer, Homer Dudley's VODER (Voice Operating Demonstrator), was shown at the 1939 World's Fair. The VODER was based on Bell Laboratories' vocoder (voice coder) research of the mid-thirties.