Output Devices

1. L E C T U R E 6
D e c e m b e r , 2 0 1 8
IT in Business - I

2. Output Devices
Monitors
CRT & LCD
Printers
Impact Printers
Non-impact Printers
Plotters
Other Output Devices

3. Monitors
 A monitor is a peripheral device which displays computer
output on a screen.
 Screen output is referred to as soft copy.
 Types of monitors:
 Cathode-ray tube (CRT)
 Liquid Crystal Display (LCD or flat-panel)
 Light-emitting Diode (LED)
3
CRT
LCD

4. Monitors - CRT Monitors
• In CRT monitors, electrons are fired at phosphor
dots on the screen.
• The dots are grouped into pixels, which glow when
struck by electrons.
• In color CRTs, each pixel contains a red, green, and
blue dot.
• These glow at varying intensities to produce color
images.

6. Monitors - Flat-Panel Monitors
• Most flat-panel monitors use Liquid Crystal Display
(LCD) technology.
• Passive matrix LCD uses a transistor for each row and
column of pixels. The color displayed by a pixel is
determined by the electricity coming from the transistor.
• Active matrix LCD uses a transistor for each pixel on the
screen.
• Thin-film transistor (TFT) displays use multiple
transistors for each pixel.
• TV sets are CRTs and many desktop monitors use this
technology
• LCD is primarily used for laptops and other portable devices

7. Flat-panel monitors take up less
desk space.

8. Monitors - Light-emitting Diode (LED)
 Less space
 Lighter
 Very expensive
 Provide higher contrast and better viewing angles
than LCD monitor

9. Monitors - Comparing Monitors
When comparing monitors, consider four features:
• Size
• Resolution
• Refresh rate
• Dot pitch

10. Comparing Monitors - Size
 Screen size – The diagonal measurement of the screen surface in inches (15,
17, 19, 21)
The diagonal
size (often 15”)

11. Comparing Monitors - Resolution
• Resolution is the number of pixels on the screen, expressed as a
matrix (such as 600x800).
• It is the image sharpness of a display screen.
• It is expressed as a matrix.
• A resolution of 640x480 means there are 640 horizontal pixels and
480 vertical pixels.
• Most monitors provide the resolution 640x480, 800x600 and
1024x768

12. Resolution (image sharpness) is
important.
(Especially for graphics, page layout, and CAD)

13. Comparing Monitors - Refresh
Rate
• Refresh rate – The speed at which the screen is redrawn
(refreshed).
• Refresh rate is the number of times each second that
the electron guns scan the screen's pixels.
• Refresh rate is important because phosphor dots fade quickly
after the electron gun charges them with electrons.
• Refresh rate is measured in Hertz (Hz), or cycles per second.

14. Fast scanning = Quick refresh (less flicker)

15. Comparing Monitors - Dot Pitch
• The distance between the phosphorus dots create a single pixel is called dot pitch.
• Dot pitch is the distance between the like-colored phosphor dots of adjacent
pixels.
• In other words, if you measure the distance between the red dots of two adjacent
pixels, you are measuring the monitor’s dot pitch.
• In color monitors, three dots (red, green, and blue) comprise each pixel.
• Look for a dot pitch no greater than .28 millimeter.

16. R + BB + G
R + G
R + B + G
Phosphor Dot Color Mixing

18. Printers
 A printer is a peripheral device that produces a physical copy or hard copy
of the computer’s output.
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19. Overview of Printers
Categorizing Printers
 Printers fall into two categories:
1. Impact Printers
2. Non Impact Printers
 Impact printers creates an image by using pins or hammers to
press an inked ribbon against the paper.
 A simple example of impact printer is a type-writer, which uses small hammers to
strike the ribbon.
 Each hammer is embossed with the shape of a letter, number or symbol; that shape is
transferred through the inked ribbon onto the paper, creating a printed character.
 The most common type of impact printer is the “dot matrix printer”.
 Another example of impact printer is line printers

20. Overview of Printers - Categorizing
Printers
 Printers fall into two categories:
 Non-impact printer prints character and graphics on a piece of paper without
striking the paper.
 Non-impact printers use different methods to place ink (or another substance) on
the page.
 Ink jet printers, for example, use tiny nozzles to spray droplets of ink onto the
page.
 Laser printers work like photocopiers, using heat to bond microscopic particles
of dry toner to specific parts of the page.

21. Overview of Printers - Evaluating
Printers
 When evaluating printers, consider four criteria:
 Image quality – Measured in dots per inch (dpi). Most printers
produce 300 – 600 dpi.
 Speed – Measured in pages per minute (ppm) or
 characters per second (cps).
 Initial cost – Consumer printers cost $250 or less, but
 professional printers can cost thousands of dollars.
 Cost of operation – This refers to the cost of supplies used by the
printer.

22. Dot Matrix Printers -
How Do Dot Matrix Printers Work?
 A dot matrix printer is the example of impact printer
 A dot matrix creates an image by using a mechanism called a “print head”,
which contains a cluster (or matrix) of short pins arranged in one or more
columns.
 On receiving instructions from PC, the printer can push any of the pins out in
any combination.
 The protruding pins’ end strike a ribbon, which is held between the print head
and paper.
 When the pins strike the ribbon, they press ink from the ribbon onto the paper.

24. Dot Matrix Printers - Performance
 Lower-resolution dot matrix printers use nine pins. Higher-resolution models
have 24 pins.
 Speed is measured in characters per second (cps). Some dot matrix
printers print 500 cps.

25. Ink Jet Printers –
How Do Ink Jet Printers Work?
 Ink jet printers are an example of non-impact printers.
 The printer sprays tiny droplets of ink onto the paper.
 Ink jet printers are available for color and black-and-white printing.
 Color ink jet printers have four ink nozzles: cyan (blue), magenta (red), yellow
and black. (CMYK printers)
 Printed color is the result of light bouncing off the paper, not color transmitted
directly from a light source.
• A stepper motor moves the print head assembly (print head and ink cartridges)
back and forth across the paper.

27. Ink Jet Printers - Performance
 Ink jet printers offer speeds of (2 – 4 pages per minute ppm) and resolution (300 –
600 dots per inch dpi), comparable to low-end laser printers.
 Ink jet printers are inexpensive and have low operating costs.

28. Laser Printers –
How Do Laser Printers Work?
 Laser printers are non-impact printers with a laser at the
heart of these printers.
• Just as the electron gun in a monitor can target any pixel, the laser in a laser
printer can aim at any point on a drum,creating an electrical charge.
 A CPU and memory are built into the printer to interpret the data that it received
from the computer and to control the laser.
 They use heat and pressure to bond particles of toner to paper.
 Laser printers are available for color and black-and-white printing.

30. Laser Printers - Performance
 Laser printers provide resolutions from 300 – 1200 dpi and
higher.
 Black-and-white laser printers usually produce 4 – 16 ppm.
 Laser printers produce higher-quality print than ink jet printers, but are more
expensive.

31. Other Types of Printers
Photo Printers
• Photo printers are specialized, small-format printers
that print digital photographs.
• Photo printers are fairly slow, and can be more
expensive to operate
• Many photo printers use ink jet technology.
• One advantage of the newest photo printers is that
they don’t need a computer. These printers feature
slots for memory cards used by many digital cameras.
Photo printers are popular among
digital camera users

32. Other Types of Printers
 A multifunction peripheral (MFP) is a single device that prints, scans, copies, and in some cases,
faxes
 Sometimes called an all-in-one device

33. Other Types of Printers
 A thermal printer generates images by pushing electrically heated pins against the heat-sensitive
paper
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Thermal wax-transfer printer
Dye-sublimation printer

34. Plotters
 A plotter is specialized output device. It is designed to produce
image-quality graphic in a variety of colors and size.
 Plotters are used to create maps, architectural drawings and 3-D
illustration.
 A plotter works by drawing lines on paper using pens held in
mechanical arm

35. Drum Plotter
Flat-bed
Plotter
Ink jet Plotter
cutting Plotter

36. Other Output Devices
 Headphones are speakers
that cover your head or are
placed outside of the ear
 Earbuds (also called
earphones) rest inside the ear
canal
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37. Other Output Devices
 A data projector or PC
projector is a device that
takes the text and images
displaying on a computer
screen and projects them on a
larger screen
 Many PC projectors provide
the same resolutions and
color levels as high-quality
monitors.
 Digital light processing (DLP)
projectors use a microchip
containing tiny mirrors to
produce very sharp, bright
images.

38. Thank you…!!!!!