Monitors by hcj

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									Module 3 – Ouput Methods
Michaelston Community College

                                    Monitors

A monitor is a screen used for computer output. The size of a monitor is
measured diagonally across the screen.

Older type monitors use CRT (cathode ray tube) technology.

The resolution of a monitor is a measure of the number of pixels
displayed. A pixel is the smallest amount of the screen that can be
changed by the computer - ie a 'dot' that makes up a picture.

TFT (Thin Film Transistor) screens are being developed
which allow for much thinner monitors.

In a TFT display every pixel is controlled by a number of
transistors.
Liquid Crystal Displays (LCDs) are frequently used on
laptop computers. They are now available in high
resolution and colour, but there is often a limited viewing
angle.



                        Plasma screens also allow very thin monitors.

                        Plasma consists of a surface made of millions of tiny
                        gas-filled glass 'bubbles'.
                        Still expensive but large screens are possible (up to
                        60")



Exercise : Monitors
Monitors are ……………………….. devices.

Older ones use ………………………. but …………………………………… are
used in laptops.

Thinner and larger monitors are available using TFT (thin film transistors) or
…………………………………………… but they are expensive.




Mr G. E. Parsons                                                      Page 1 of 5
Module 3 – Ouput Methods
Michaelston Community College

                                 Laser Printers

Prices of laser printers are falling rapidly, so they are becoming one of the
most popular printers. Laser printers use a process similar to a photocopying
machine, with toner (very fine powder) being transferred to the page and then
fused on to it by heat and pressure.

A laser printer produces output of high quality, and is virtually silent (a good
idea in a busy office).

Mainframe computers may have high-speed laser
printers for high-volume work, operating at about
400 pages per minute.(eg printing bank
statements, electricity bills, junk mail etc)



 Colour laser printers are expensive (..but you can
now get one for under £1,000). They work by
printing 4 times.....Once with Cyan toner, then with Magenta toner, then
Yellow then Black.


A Laser printer may be combined with a scanner, a photocopier and a fax
machine.

                                 Inkjet Printers

Inkjet printers produce an image by spraying ink onto the paper.

They are cheaper than laser printers but can be expensive to run - the ink
cartridges are not cheap.

They can produce good quality output on special paper.

Colour graphics may be produced by spraying cyan,
magenta, yellow and black inks.



Other types of printer include dot-matrix printers (which produce characters
consisting of dots by hammering pins onto a ribbon), fast but poor quality
print, useful for multiple-part stationery......
 ...and thermal printers (which applies heat to heat-sensitive paper.) - may be
used to print receipts at POS terminals.




Mr G. E. Parsons                                                      Page 2 of 5
Module 3 – Ouput Methods
Michaelston Community College

                                Graph plotter

Graph plotters are used to produce high quality precision graphics usually on
large sheets of paper.

They are slow, but can draw
continuous curves often in a variety
of colours. They are especially
useful for architectural drawings,
building plans and CAD (Computer
Aided Design) applications, where
precision drawing is required.


A mechanical arm holds a pen which can be moved across the page. The
paper is sometimes laid on a flat bed (flat bed plotter) ...
 ...or on a rotating drum (drum plotter).

                                Sound Output

Sound may be output using a speaker.
Sound cards need to be installed in microcomputers to obtain good quality
sound for music software or games.


Speech synthesis output may be used for visually handicapped people, and
may be used to send personal messages in voice form across an Email
network.

On fast networks real-time speech may be implemented using microphones
and speakers.
 Some computers in cars can produce voiced warnings. Some children's toys
and educational games use speech synthesis (eg for teaching spelling).
You can learn languages over the Internet...

Multi-media means a mixture of text, sound and pictures.

Exercise : Sound Output

Computers may output sound such as speech or music using
………………………….
…………………………….may need to be installed.




Mr G. E. Parsons                                                  Page 3 of 5
Module 3 – Ouput Methods
Michaelston Community College

                             Control Systems

The output from a computer may be in the form of a signal to a hardware
device.
In a control system, sensors are used to measure a physical quantity and
send input to the controlling computer.

The computer responds by sending an output signal to a control interface
which activates various devices eg a switch or an alarm.

The output signal may be sent a to an actuator which activates a mechanical
device such as a motor.

Commonly used sensors are - heat sensors, light sensors, sound sensors,
humidity sensors, movement sensors.
The control interface is needed because of the different operating
characteristics of the computer and the devices.

Example:
A computer may be used to control a greenhouse.
Sensors continually send information about the
temperature and humidity in the greenhouse to the
computer.

The computer will then analyse the data and send output
signals, if necessary, to activate the ventilators or
sprinkler systems.


Exercise : Control systems

In a control system output from a computer may be in the form of an
………………………….. sent to a device such as a switch or an alarm.

A ………………………………………….. is usually needed between the
computer and the device.

The signal may be sent to an ………………………………… which operates a
mechanical device.




Mr G. E. Parsons                                                 Page 4 of 5
Module 3 – Ouput Methods
Michaelston Community College

                                      COM

COM is a technique of reducing documents in size and photographically
printing them so that they can be read using a special magnifying machine.

Microfilm is a roll of film and microfiche is a rectangular sheet of film on which
many frames (pages of information) can be stored.

Microfiche readers are needed to read the very small text and pictures.
Example : Newspapers might be archived on microfiche.

Advantages :

uses much less storage space
film lasts longer than paper

                                      CAM

CAM stands for Computer Aided Manufacture.
Output from a computer is used to control CNC manufacturing machines such
as millers or lathes...or even knitting machines. (CNC stands for Computer
Numerical Control and means that instructions for the machines are given as
numbers.)

CAD/CAM is the whole process of design and manufacture using computers.
CAD is used to produce the design of a product and the code to run the CNC
machine is output. The machine then manufactures the product.

Exercise : CAM

CAD stands for ……………………………….
and CAM stands for . ………………………………..

Products may be designed on the computer and output is sent to
a CNC …………………………………. machine such as a lathe or a milling
machine which makes it.




Mr G. E. Parsons                                                      Page 5 of 5

								
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