TYPES OF OUTPUT: Text Graphics Audio Video Hard Copy / Soft copy

OUTPUT DEVICES: Printers Plotters Monitors/ VDU

PRINTERS As peripheral which produces a text or

graphics of documents stored in electronic form, usually on physical print media such as paper or transparencies. 

Impact printers Daisy wheel

2. Dot matrix Non Impact printers

Tonner based (Laser)2. Liquid ink(Inkjet)

DOT MATRIX PRINTERS  Impact printers that use a matrix of

small pins to create precise dots.  Dot-matrix printers use a set of

closely spaced pins and a ribbon to print letters or other characters on a page. 

Dot-matrix printers vary in terms of speed and the number of pins they have. They can run at a speed anywhere between 50 and 500 CPS (Characters Per Second). 

DAISY WHEEL PRINTERS Daisy-wheel printers operate in much

the same fashion as a typewriter. A hammer strikes a wheel with petals,

the "daisy wheel", each petal containing a letter form at its tip. The letter form strikes a ribbon of ink, depositing the ink on the page and thus printing a character. By rotating the daisy wheel, different characters are selected for printing. 

LINE PRINTERS / CHAIN PRINTERS Line printers, as the name implies,

print an entire line of text at a time  In chain printers, also known as train

printers, the character set is arranged multiple times around a chain that travels horizontally past the print line. In either case, to print a line, precisely timed hammers strike against the back of the paper at the exact moment that the correct character to be printed is passing in front of the paper.

INK-JET PRINTERS Ink-jets(bubble-jets) printers spray

ionized tiny drops of ink onto a page to create an image.  This is achieved by using magnetized plates which direct the ink's path onto the paper in the desired pattern.

Ink-jet printers are capable of producing high quality print which almost matches the quality of a laser printer.

LASER PRINTER: Laser printers operate by shining a laser

beam to produce an image on a drum. The drum is then rolled through toner, and the electrically charged portions of the drum pick up ink. Finally, using a combination of heat and pressure, the ink on the drum is transferred onto the page. 

Color laser printers use the same toner-based printing process as black and white ( B/W) laser printers, except that they combine four different toner colors.  Color laser printers can also be used as a regular black and white laser printer.

THERMAL PRINTER That uses heat process to transfer colored dyes

or inks to the paper Photo Printer: A photo printer is a color printer

that can produce images that mimic the color range (gamut) and resolution of prints made from photographic film. Many can be used on a standalone basis without a computer, using memory card or USB connector.

Portable Printer: Small light weight and battery powered printer. It uses ink jet, thermal, technology and connects to parallel or USB port

Label / Postage Printer: Small printer that prints on adhesive type material that can be placed on different items like envelopes, packages, CDs, toys etc

PLOTTER A plotter is a vector graphics printing

device which operates by moving a pen over the surface of paper

 large-scale printers that are very accurate at reproducing line drawings. 

They are commonly used for technical drawings such as engineering drawings or architectural blueprints

TYPES OF PLOTTER Flatbed plotter: A graphics plotter that

contains a flat surface that the paper is placed on. The size of this surface (bed) determines the maximum size of the drawing. A graphics output device that draws by moving a pen in both horizontal and vertical directions over a sheet of paper; the overall size of the drawing is limited by the height and width of this bed.

Drum plotter: In drum plotters the pen is moved in a single axis track and the paper itself moves on a cylindrical drum to add the other axis or dimension.

MONITORS: Size:

13 to 16 inches, measured diagonally Color:

Monochrome/ Colored MonitorColor depth/ Bit Depth: No of colors a monitor can

display Resolution:

No of pixels(picture elements) on screenMore resolution, better image

Refresh rate/ Vertical Scan rate/Vertical frequency:Speed with which monitor redraws image

Dot pitch Distance between each pixel on monitorSmaller dot pitch, better image quality

VIDEO DISPLAY ADAPTERS: Video Graphics Card: Circuit board that

determines:ResolutionNo of colorsSpeed with which images appear on monitor

screen

TYPES OF VIDEO GRAPHICS CARD: Video Graphics Array (VGA)

4 BIT color, 16-256 colors at 640 X 840 PIXELS Super Video Graphics Array (SVGA) 8 bit/ true color, 256colors at 1024 x 768 pixels 15 inch monitors Extended Graphics Array (XGA) 24 bit/ true color, 16.7 million colors at 1024 x 768

pixels 17-19 inch monitors Super Extended Graphics Array (SXGA) 1280 x 1024 pixels 19-21 inch monitors Ultra Extended Graphics Array (UXGA) 1600 x 1200 pixels 21 inch monitors

COMPUTER DISPLAY SYSTEMS CRT- Cathode Ray tube- the same

technology employed by your television- an electron gun scans the screen causing special chemicals called ‘phosphors’ to glow- the gun scans from top to bottom, left to right

Video Adapter- an expansion board or integrated device that renders characters for display in response to commands from the computer- it tells the display device how to draw the graphic

VIDEO TECHNOLOGIES Monochrome- two color video- text only with a

resolution of 720 x 350 Color Graphics Adapter- CGA- four colors- 320 x 200

resolution for graphics, 640 x 200 for two color Enhanced Graphics Adapter- EGA- 16 colors- 320 x

200 graphics, 640 x 350 text Video Graphics Array- VGA- introduced with the IBM

AT form factor motherboards- used an analog signal- 256KB of video memory on board- 16 colors at 640 x 480 or 256 colors at 320 x 200

Super Video Graphics Array- introduced by the Video Electronics Standards Association- 65, 536 colors at 640 x 480, 256 colors at 800 x 600 or 16 colors at 1,024 x 768

Extended Graphics Array- IBM’s answer to the SVGA, XGA could only use the MCA expansion bus- it also used interlacing, or scanning every other line on each pass- offered the same resolution options as the SVGA

DISPLAY QUALITY MEASUREMENTS Dot Pitch- the shortest distance

between two dots of the same color on the monitorMeasured in millimetersThe lower the number, the sharper the

image .28mm is considered average- anything

smaller is great Refresh Rate- vertical scan

frequency- how many times in one second does the electron beam redraw the screen? The standard is 60Hz for VGA

DISPLAYS Most desktop displays

use a cathode ray tube (CRT), while portable computing devices such as laptops incorporate liquid crystal display (LCD)

Because of their slimmer design and smaller energy consumption, monitors using LCD technologies are beginning to replace the venerable CRT on many desktops

CRT MONITOR

How a CRT monitor works

CRT MONITOR The cathode ray tube is a vacuum

tube containing an electron gun (a source of electrons) and a fluorescent screen used to view images

 A CRT works by moving an electron beam back and forth across the back of the screen. Each time the beam makes a pass across the screen, it lights up phosphor dots on the inside of the glass tube, thereby illuminating the active portions of the screen. 

/Flat panel

FLAT PANEL MONITORS: These are light weight, takes less space

and use less power as compared to CRTs Doesn’t emit harmful radiations but is

expensive then CRT Technologies of Flat panel Monitors:

Liquid Crystal DisplayGlass Plasma

LCD MONITORS LCD displays use two sheets of polarizing

material with a liquid crystal solution between them. An electric current passed through the liquid causes the crystals to align so that light cannot pass through them. Each crystal, therefore, is like a shutter, either allowing light to pass through or blocking the light. 

FEATURES OF A MONITOR

FEATURES Two measures describe the size of your

display:The aspect ratio and the screen size.

Aspect Ratio: Most computer displays, like most televisions, have an aspect ratio of 4:3

This means that the ratio of the width of the display screen to the height is 4 to 3.

Screen SizeHow to MeasureDesktop vs. Laptop

FEATURES Scan or Refresh Rate, or vertical scan rate

The time it takes for the electronic beam to fill the screen with lines from top to bottom The number of times that the image on the display is

drawn each second. If your CRT monitor has a refresh rate of 72 Hertz (Hz),

then it cycles through all the pixels from top to bottom 72 times a second.

Control flicker You want the refresh rate as high as possible

Standard rate established by the Video Electronics Standards Association (VESA) is 70Hz, or 70 refreshes per second

FEATURES Multiscan

Multiscan monitors support a variety of refresh rates and can support different video cards

Fixed frequency monitors only support a single refresh rate

Interlace features Interlaced monitors draw a screen in 2 passes,

hitting the even lines first, then the odd linesNon-interlaced monitors draw the entire

screen in 1 pass

FEATURESDot Pitch

The distance between adjacent dots on the screen. The smaller the dot pitch, the higher the quality of

the image. A high-quality monitor should have a dot pitch of

no more than .28mm A display normally can support resolutions that

match the physical dot (pixel) size as well as several lesser resolutions.For example, a display with a physical grid of

1280 rows by 1024 columns can obviously support a maximum resolution of 1280x1024 pixels but it usually also supports lower resolutions such as 1024x768, 800x600, and 640x480.

MONITORSResolution

A measure of how many dots on the screen are addressable by software

Each addressable location is called a pixel (picture element)

Most monitors offer a resolution of 1024 x 768 or higher

The video controller card as well as the monitor must be capable of supporting the chosen resolution.

Resolutions are set from the Control Panel in Windows 9X

FEATURES Color Depth

The combination of the display modes supported by your graphics adapter and the color capability of your monitor determine how many colors can be displayed.

Bit Depth : The number of bits used to describe a pixel is known as its bit depth. For example: with a 24-bit bit depth, 8 bits are

dedicated to each of the three additive primary colors -- red, green and blue. This bit depth is also called true color because it can produce the 10,000,000 discernible colors.

GLASS PLASMA DISPLAY A plasma display panel (PDP) is a type

of flat panel display common to large TV displays 30 inches (76 cm) or larger.

They are called "plasma" displays because the technology utilizes small cells containing electrically charged ionized gases, or what are in essence chambers more commonly known as fluorescent lamps.

Active matrix display: Each pixel is controlled by its own transistor.

An active matrix liquid crystal display (AMLCD) is a type of flat panel display, currently the overwhelming choice of notebook computer manufacturers, due to low weight, very good image quality, wide color gamut and response time.

Passive matrix display / Dual scan monitor: Two transistors control a whole row or column of pixels each at the same time.

TOUCH SCREEN MONITORS:

A touchscreen is an electronic visual display that can detect the presence and location of a touch within the display area. The term generally refers to touching the display of the device with a finger or hand.

WHAT IS A PROJECTOR?

Dictionary.com says a projector is a machine for projecting an image onto a screen or other surface.

THE DIFFERENT TYPES

This is the CRT projector

This is the DLP

This is an LCD projector

LCDLCD (liquid crystal display) projectors work by passing a very strong beam of light through a transparent LCD chip, that has the video playing on it.

AdvantagesSome advantages to LCD projectors is that they are very compact because the LCD chip is so small. Another thing is that they have high contrast and brightness capability and they have a very low power consumption.