CAD Hardware

MT 21_CAD/CAM 3(1-2) Components of CAD/CAM/CAE Systems Lecture: Week 2

Than Lin, Ph.D. Instructor, Undergraduate Program Asian Institute of Technology

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

Reading Assignment

- Chapter 2 Page 18-35

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

Outlines - Introduction - Hardware Components - Vector Refresh (Stroke-Refresh) Graphics Devices - Raster Graphics Devices - Hardware H d Configuration C fi ti - Software Components - Windows Windows-Based Based CAD System

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

Introduction Graphics Devices and their peripherals for input and output operations CAD/CAM/CAE System

Hardware

Computing machine

Software

Graphics device

Display processing unit Display device Input device Output device CAD/CAM 3(1-2), AIT-UG (January’ 2013)

Hardware Components •

Examples p of input p devices: - mouse - data tablet with a puck and stylus - space ball

CAD/CAM/CAE System

Hardware

•

Example of output devices: - Plotter & color laser printer

Computing machine

Software

Graphics device

Display processing unit Display device Input device Output device

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

I Input D Devices i ƒ ƒ ƒ

physical h i l devices d i logical devices input modes − request mode − sample mode − event mode

Keyboards

Dials

Touch Panels

Li h Pens Light P

Graphics p Tablets

3D Tablets

Joysticks / Mice / Trackballs

Buttons

Voice Systems

Logical g Devices ƒ ƒ ƒ ƒ ƒ ƒ

locator stroke stringg valuator choice pick

Locator Devices / Stroke Devices

String Devices y+

(a)

y - axis

(b)

Valuator Devices 1

90

0.5 0

0

180

-0.5 -1

270

0

5000

Choice Devices ‰buttons ‰menu selection

Pick Devices bounding rectangle

ymax

ymin xmin

xmax

d

d1 (x,y)

2

Graphics Displays ƒ CRT (Cathode ray tube) - Electron beam on phosphor coated screen ƒ Laser - Laser beam is used to trace an image in a film. ƒ LCD (Liquid Crystal Display) - LCD and light emitting diodes (LEDs) are used to generate images ƒ Plasma Display p y - It uses small neon bulbs arranged in a panel which provides a medium resolution display

Vector Refresh (Stroke-Refresh) Graphics Devices

- Introduced in the mid 1960s. 1960s - Composed of Display processing unit, Display buffer memoryy and a cathode rayy tube - A display buffer- the display list is stored in the portion of memory

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

Components of a vector-refresh graphics device computer display commandss

… … MOVE 10 0 15 LINE 100 25 CHAR LU CY LINE … … JMP

interaction n data

Display buffer

Display Processing Unit

CRT stylus

alphanumeric keyboard

data tablet

The display list is stored in the portion of memory called a display buffer. CAD/CAM 3(1-2), AIT-UG (January’ 2013)

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

ffocusing i system

horizontal d fl i deflection plate

heating filament

electron beam

cathode control grid

accelerating system

vertical deflection plate

phosphorcoated screen

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

1/30 second ? Redrawn within 1/30 second. Redrawing process is called refresh. User will U ill nott notice ti th the di disappearance off th the iimage if it iis re drawn within 1/30 second

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

Raster Graphics Devices

Components of a raster graphics device CAD/CAM 3(1-2), AIT-UG (January’ 2013)

Components of a raster graphics device

interface to host computer ((display p y commands))

00000000000000000000000001000000 00000000000000000000000001000000 00000000000000000000000111110000 00000000011000000001111111111111 00000000111100000000000111110000 00000011111111000000000001000000 00001111111111110000000001000000 00111111111111111100000000000000 00011111111111111000000000000000 00011111111111111000000000000000 00011111111111111000000000000000 00000000000000000000000000000000

((interaction data))

display processor

keyboard y data input

CRT

frame buffer

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

Raster Graphics Devices

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

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

Th picture The i t iis approximation i ti off an iimage as a group off d dots t or pixels. i l CAD/CAM 3(1-2), AIT-UG (January’ 2013)

Interlacing accelerating technique of refreshing

even scan-line field odd scan-line field 1 2 3 4 5 6 7 8

vertical retrace horizontal retrace

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 will be constant regardless of the complexity of the image image. - Refresh time is time required to scan the electron beam from the top scan line to the bottom scan line . - Usually 1/30 second for normal TV set and 1/60 second for high-end raster graphic devices.

Frame buffer for B/W display

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

Example of 3-bit planes Red Black Red Green Blue Yellow Cyan Magenta White

0 1 0 0 1 0 1 1

Green 0 0 1 0 1 1 0 1

Blue 0 0 0 1 0 1 1 1

Consider the use of three bits for each pixel! CAD/CAM 3(1-2), AIT-UG (January’ 2013)

Color definition, using 24-bit planes

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

Color CRT (Shadow Mask)

Each of these pattern corresponds to one dot in the frame buffer buffer. CAD/CAM 3(1-2), AIT-UG (January’ 2013)

Shadow mask

phosphors on glass faceplate

electron guns

phosphors on glass faceplate

blue green

electron guns

blue green red

red

metal mask

delta-delta delta delta shadow-mask shadow mask CRT

metal mask

precision in-line in line delta CRT

For example, the gun associated with the red phosphor may shoot at green phosphor, To prevent shadow mask is positioned and ensures that each electron beam will hit only the associated phosphor.

ƒ When Wh hit b by an electron l t b beam, phosphor h h emits it lilight ht −

fluorescence

−

phosphorescence p p

Í

Persistence How llong a phosphor H h h continues ti tto emit it lilight ht 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

Refreshing

intensity

10 % persistence

Refresh rate

‰ # of times/sec a picture is redrawn ‰ 60 Hz for raster scan displays

time

Plasma Panel Display ƒ CRT Di Display l – Not N t suitable it bl particularly ti l l ffor portable t bl applications li ti because b of the depth that is necessary to the Cathode Ray Tube. ƒ

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

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

Liquid Crystal Display (LCD) ƒ Liquid crystals exist in a state between liquid & solid. ƒ Molecules of liquid crystals free to move around ƒ Actually closer to a liquid state than solid state (sensitive to temperature) ƒ The arrays of liquid crystals become opaque when field is applied for displaying image. ƒ Low power consumption has made them suitable for portability. ƒ Very small destop space while reducing the power consumption. ƒ The price falling rapidly, rapidly thus becoming more popular. popular ƒ Large scale of LCD monitors

Hardware Configuration C fi i

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

Hardware configuration, using a mainframe

Mainframe

Graphics device

Interactive input device

Graphics device

Interactive input device

Graphics device Plotter Graphics device

- The first Configuration is composed of a main frame computer and multiple graphics devices. - It requires a big initial investment - System response time for graphic devices -Automobile and ship building company are still using CAD/CAM 3(1-2), AIT-UG (January’ 2013)

Hardware configuration, using engineering workstations

-The user can choose the computing power of any work station - Avoidance of large initial investment - Installation can be increased related to CAD/CAM/CAE - Prices of hardware continues to drop dramatically

-The third configuration is the same as the second -Engineering E i i work k stations t ti are replaced l d with ith personall computers t -This configuration is popular in companies

Software Components

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

Some Typical CAD/CAM/CAE Software

Application Area

Software

Integrated System

CAD-2D drafting

CADAM, AutoCAD

CAD-Solid CAD Solid modeling

Solid Edge, Edge SolidWorks Mechanical Desktop

CAM

VERICUT, MasterCAM PowerMILL

Pro/Engineer Unigraphics CATIA I-DEAS I/EMS EUCLID - IS

CAE

MSC/NASTRAN, ANSYS PATRAN,ADAMS,C MOLD PATRAN,ADAMS,C-MOLD MOLDFLOW

Figure: Fig re Prod Product ct Cycle C cle Ref: Principles of CAD/CAM/CAE Systems

Example 1 An eight-plane g p raster display p y 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 (b) Th The time i to display di l a scan line li ts andd a pixel i l tp are given i by b ts = (1/60)/(1024) =16 microseconds tp = 16/1280 = 12 nanoseconds (c) The active display area = 1280/78 horizontal x 1024/78 vertical= 16.4x13.1 inch