We can send sound to the computer through a special manual input device called microphone or mic. A mic converts the received sound into computer’s format, which is called Digitized Sound or Digital Audio. To convert a voice into digital form, an additional hardware is always needed which is known as Sound Card.
Sound is used most often in multimedia, where user can make his/her presentation more attractive using recorded narration, music or sound effects.
A microphone can be attached to a computer to record sound. Now-a-days, microphones are also being used with speech recognition software.
This means that you do not have to type the document, rather just have to speak and the spoken words appear in your document.
Web Camera (Webcam)
Webcam is a digital camera attached to computers and can be used for video conferencing or online chatting, etc. It is a video capturing device. Webcams are able to capture full motion videos as well. A webcam connected to a computer allows the user to view either a still picture or motion video of a user or other object.
Now-a-days, webcams are either embedded into the display with laptops or connected via USB or fIrewire port or Wi-Fi to the computer system. After connecting webcam to a computer, you need to install required software or drivers.
Digital Camera (Digicam)
It is a device that stores the pictures or videos in an electronic format instead of film. There are several features that makes digital camera a popular choice, when compared to film cameras. Most enjoyable feature is the LCD display on the digital camera. This display allows users to view and save photos or video after the picture or video has been taken, that means, if you take a picture and don’t like the results, you can delete it, or if you like the picture, you can save it and easily show it to other people.
It is a device which recognizes physical or behavioral traits of the individual. Biometric sensors are mainly used marking Biometric attendance of employees! Sensor studentsin organizations / institutions. Biometric sensors are working with accuracy, so these can be widely used in security purpose.
An output device is a part of computer hardware equipment, used to communicate the results of data processing which are carried out by an information processing system (such as a computer), to the outside world. Output devices carry the results of various operations performed by the user. Some of the devices, which are used to display the processed result or output are as follows:
A monitor (called a visual display unit) is an electronic visual device used to display the output. The rectangular area of the monitor, its refresh rate and dot pitch, all directly affect the resolution of the display.
Resolution refers to the clarity of screen and measured by the number of individual tiny coloured dots (knows as pixels), scattered on the screen. Resolution indicates the number of dots per inch. The smaller the dot pitch is, the better the resolution will be.
Types of Monitors
The popular type of monitors are as follows:
(i) CRT (Cathode Ray Tube) The CRT works in the same way as a television. It contains an electron gun at the back of the glass tube. This gun fires electrons in a group of phosphor dots, which is coated inside the screen. When the electrons strike the phosphor dots they glow to give the colors
(ii) LCD (Liquid Crystal Display) These screens are used in laptops and notebook sized PCs. A special type of liquid is sandwiched between two plates. It is a thin, flat and light weight screen made up of any number of colors or
mono-chrome pixels arranged in front of a light source. Some of the major features of LCD monitors are:
- Long life
- Light weight
- Better screen privacy
- Less eyestrain
- Reduced radiation
(iii) LED (Liquid/Light Emitting Diode)
LED is an electronic device that emits light when electrical current is passed through it. LEDs usually produces red light, but today’s LEDs can produce RGB (Red, Green and Blue) light and white light as well.
(iv) 3-D Monitor
Impact printer’s varieties includes: 3-D Monitor is a television that conveys depth perception to the viewer 3-D describes an image that provides the perception of length. When 3-D images are made interactive, user feels involved with the scene and this experience is called virtual reality.
TFT (Thin Film Transistor) —i
TFT and Active-Matrix LCD (AMLCD) is a Liquid Crystal Display (LCD). With active-matrix displays, each pixel is controlled by one to four transistors that can make the screen faster, brighter, more colourful than passive-matrix and capable of being viewed at different angles. Because of this improved technology, active-matrix screens are often more expensive but have better quality than a passive-matrix display.
A printer is an output device, which produces a hard copy of documents that are stored in an electronic form on physical print media such as paper or transparencies. So printers are the primary output devices used to prepare permanent documents. The speed of a printer is normally rated either by Pages Per Minute (PPM) or by Characters Per Second (CPS).
Printers can be classified into two broad categories
(i) Impact Printers
(ii) Non-Impact Printers.
(i) Impact Printers
Impact printers rely on a forcible impact to transfer ink to the print media, similar to the action of a typewriter. There is a mechanical contact between the paper and the print head.
(a) Line Printer These are impact shaped character printers which capable of printing an entire line at one instead of one or more character at a time. Print quality of line printer is not high.
(b) Drum printer It is an old line printer technology that is used to formed character images around a Drum printer
cyhndncal drum as its printing mechanism. When the desired character for the selected position rotated around the hammer line, the hammer hit the paper from behind and pushed it into the ribbon and onto the character.
(c) Daisy wheel printer It can print one character at a time. In daisy wheel printer, round disk extends a portion of the wheel making contact with ink ribbon that makes contact with paper for creating the character. This procedure is repeated for each key when it is pressed. These printers are fitted with unchangeable print heads called daisy wheels. To print each character, the wheel is rotated and the appropriate stoke struck against an inked ribbon. Daisy wheel printers cannot produce high quality print graphics. The speed of daisy wheel printer is about 100 cps.
(d) Dot matrix printer The term dot matrix refers to the process of placing dots to form an image. It uses print heads to shoot ink or strike an ink ribbon to place hundreds to thousands of little dots to form text or images. It prints one character at a time. The speed of dot matrix printer lies between 200 to 600 cps.
The quality of the image is determined by the dots per inch. These printers are slow, noisy and are not commonly used for personal computers. They can print multi-layer forms, which neither inkjet nor laser printers can print. It can print special characters and graphics. Dot matrix printer do not have fixed character fonts.
(ii) Non-impact Printers
Non-impact printers are much quieter than impact printers as their printing heads do not strike the paper. Most non-impact printers produce dot-matrix patterns. There is no mechanical contact between the paper and the print head. These printers are comparatively faster and produce high quality output. They can be used for printing text and graphics both in black and white and colored.
The main types of non-impact printers are as follows:
(a) Electromagnetic printer Electrographic or electro- photographic printers are very fast printers and they fall under the category of page printers. They can produce documents at a speed of over 20000 lines per minute i.e. more than 250 pages per minute. The electrographic technology has developed from the paper copier technology.
(b) Thermal printer Thermal printer paper tends to darken over time due to exposure of sunlight or heat. The standard of print produced is poor. Thermal printers are widely used in battery powered equipment such as portable calculators.
(c) Electrostatic printer Electrostatic printers are generally used for large format printing. They are favored by large printing shops because of their ability to print fast, making
(d) Laser Printer In laser printer, the method of printing is based on principle of electro photography
and use a beam of laser light as a photocopy machine. The powered ink (i.e. toner) is transferred to paper to form a text/image pattern and then fixed by heat or pressure. When used to print bulk of papers, the laser printer produces the cheapest cost per printout.
(e) Inkjet Printer An inkjet printer fires extremely small droplets of ink onto the paper to create —t impression of text or image. The print head of inkjet printer inkjet printers, known as print cartridge, contains tiny nozzles (50 or more) through which different colored inks can be sprayed onto the paper to form the characters or graphic images. Color inkjet printers provide an inexpensive way to print fully colored documents.