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8/12/2019 CAD Hardware

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MT 21_CAD/CAM 3(1-2)

Lecture: Week 2

Than Lin, Ph.D.

Instructor, Undergraduate Program

Asian Institute of Technology

CAD/CAM 3(1-2), AIT-UG (January 2013)


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Reading Assignment

- Chapter 2 Page 18-35



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Outlines

-

- Hardware Components

- Vector Refresh (Stroke-Refresh) Graphics Devices

- Raster Graphics Devices

- ar ware on gura on

- Software Components

- Windows-Based CAD S stem



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Introduction

Graphics Devices and their peripherals for input and output operations

CAD/CAM/CAE System

Hardware Software

Computing machine Graphics device

Display processing unit

Display device

Input device


u pu ev ce


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Hardware Components

Exam les of in ut devices:

- mouse

- data tablet with a puck and stylus

- space ball

CAD/CAM/CAE System

Example of output devices:

- Plotter & color laser printer

Hardware Software

Computing machine Graphics device

Display processing unit

Display device

Output device



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nput ev ces

p ys ca ev ces

logical devices

input modes

request mode

sample mode


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Keyboards


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Dials


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g t ens


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Gra hics Tablets


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3D Tablets


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Joysticks / Mice / Trackballs


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Buttons


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Lo ical Devices

locator

stroke

strin

valuator

pick


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Locator Devices / Stroke Devices


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+

String Devices

(a)

- axis

(b)


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Valuator Devices

901

0.5

180 0 50000

-0.5

270-1


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Choice Devices

buttons

menu selection


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Pick Devices

ymax

bounding

rectangle

ymin

d1d2

(x,y)


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Graphics Displays

- Electron beam on phosphor coated screen

Laser

- Laser beam is used to trace an image in a film.

LCD (Liquid Crystal Display)

-

Plasma Dis la- It uses small neon bulbs arranged in a panel which provides a medium

resolution display


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Vector Refresh (Stroke-Refresh) Graphics Devices

- .

- Composed of Display processing unit, Display buffer

memor and a cathode ra tube- A display buffer- the display list is stored in the portion

of memory



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Components of a vector-refresh graphics device

computerDisplay buffer

n

MOVE10 display

command

interactio

data

DisplayProcessingUnit15

LI NE

100

25

CRT

CHAR

LU

CY

LI NE stylus

J MP

alphanumeric keyboard data tablet


The display list is stored in the portion of memory called a display buffer.


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Cross-sectional view of a cathode ray tube (CRT)

horizontal

deflection

plate

focusing

system

filamentelectron beam

control accelerating vertical

deflection

cathode

phosphor-

coated

plate

screen



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1/30 second ?

Redrawn within 1/30 second.

Redrawing process is called refresh.ser w no no ce e sappearance o e mage s re

drawn within 1/30 second



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Raster Graphics Devices


Components of a raster graphics device


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Components of a raster graphics device

dis la commands interaction data

keyboard

processor data input000000000000000000000000010000000000000000000000000000000100000000000000000000000000000111110000

00000000011000000001111111111111

CRT000000001111000000000001111100000000001111111100000000000100000000001111111111110000000001000000

00111111111111111100000000000000

00011111111111111000000000000000

00011111111111111000000000000000

0001111111111111100000000000000000000000000000000000000000000000

frame buffer



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Raster Graphics Devices



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A raster-scan system displays an object as a set of points across each

screen scan line


e p c ure s approx ma on o an mage as a group o o s or p xe s.


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Interlacing

accelerating technique of refreshing

even scan-line field

1

-

3

4

horizontal retrace

5

6

7

8


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Vector-refresh device, light emission of the phosphors lasts only

brief time, and thus refresh is required.

- Only difference is the pattern in which the electron beam is scanned

for the refresh.

- .

- Refresh time is time required to scan the electron beam from the topscan line to the bottom scan line .

-

high-end raster graphic devices.

F b ff f B/W di l


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Frame buffer for B/W display



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Example of 3-bit planes

Red Green Blue

Black 0 0 0

Red 1 0 0

Green 0 1 0

Blue 0 0 1

Yellow 1 1 0

Magenta 1 0 1

White 1 1 1


Consider the use of three bits for each pixel!


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Color definition, using 24-bit planes



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Color CRT (Shadow Mask)


.


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Shadow mask

electron electronphosphorson glassfaceplate

gunsblue

green

phosphorson glassfaceplate

guns bluegreen

red

red

metal

maskmetalmask

delta-delta shadow-mask CRT -

For example, the gun associated with the red phosphor may shoot at green phosphor,

only the associated phosphor.


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Wh hit b l t b h h it li ht When hit by an electron beam phosphor emits light fluorescence

hos horescence


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Persistence

ow ong a p osp or cont nues to em t g t

after the electron beam is removed

The persistence of a phosphor is defined as the time

for emitted light to decay to 1/10 of its original intensity


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Refreshing

intensity

timepersistence

Refresh rate # of times/sec a picture is redrawn

60 Hz for raster scan displays


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Plasma Panel Display

sp ay o su a e par cu ar y or por a e app ca ons ecause

of the depth that is necessary to the Cathode Ray Tube.

Plasma uses a neon gas in a glass envelope with electrodes fore and aft to

display images.

Though small and flat, they consume a large amount of power and alsothe resolution is not very good.

i i C i ( C )


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Liquid Crystal Display (LCD)

Liquid crystals exist in a state between liquid & solid.

Molecules of liquid crystals free to move around

Actually closer to a liquid state than solid state (sensitive to temperature)

The arrays of liquid crystals become opaque when field is applied for

displaying image.

Low power consumption has made them suitable for portability.

Very small destop space while reducing the power consumption.

e pr ce a ng rap y, us ecom ng more popu ar.

Large scale of LCD monitors


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Hardware on gurat on



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Hardware configuration, using a mainframe

Mainframe

Graphics device Graphics deviceGraphics device

Interactive input

device

Interactive input

deviceGraphics device

The first Configuration is composed of a main frame computer and- The first Configuration is composed of a main frame computer andmultiple graphics devices.- It requires a big initial investmentt requires a big initial investment- System response time for graphic devices


-Automobile and ship building company are still using


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Hardware configuration, using engineering workstations

-The user can choose the computing power of any work station

- Avoidance of large initial investment

-

- Prices of hardware continues to drop dramatically


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-The third configuration is the same as the second

-Engineering work stations are replaced with personal computers

-This configuration is popular in companies


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Software Components



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Example 1


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Example 1

An ei ht- lane raster dis la has a resolution of 1280 horizontal x 1024 vertical and

refresh rate of 60 Hz non-interlaced. Find?

(a)The RAM size of the bit map (refresh buffer)

(b)The time required to display a scan line and pixel(c)The active display area of the screen if the resolution is 78 pixels (dots) per inch

Solution:

(a)The RAM size of the bit map = 8x 1280x 1024= 1.3 Mbytes

e t me to sp ay a scan ne ts an a p xe tp are g ven y

ts = (1/60)/(1024) =16 microseconds

p = = nanosecon s

(c) The active display area = 1280/78 horizontal x 1024/78 vertical= 16.4x13.1 inch

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