Memory display devices

Memory Display Devices
&
Computer system
DESIGNED BY:
DIGANT GORADIA
GUIDED BY:
PROF. GHANSHYAM RATHOD (E.T)

Contents
 Analog Display devices
• Cathode Ray Tubes(CRT)
 Digital Display devices
• Liquid Crystal Display(LCD)
• Light Emitting Diodes(LED)
• Segment Display
I. Seven-segment Display
II. 16-segment (starburst) Display
 Computer System
Birla Vishwakarma Mahavidyalaya
2

Content of Cathode ray tubes
 Cathode ray tubes
 Electron gun
 Principles of focusing
 Deflection of the beam
 Cathodeoluminescence
 Oscilloscope tubes
 Picture tubes
3

Cathode ray tubes
 Karl Ferdinand Braun a German physicist developed the first cold Cathode Ray
tube with magnetically beam with phosphor to produce a visible spot.
4

Theory
 The cathode ray tube (CRT) is an evacuated glass envelope containing an electron
gun(a source of electrons) and a fluorescent screen .
 An electron gun consists of a series of electrodes producing a narrow beam of
high-velocity electrons . Electrons are released from the indirectly heated cathode
.
 The intensity of the beam is controlled by variation of the negative potential of
the cylindrical control grid surrounding the cathode . This electrode is called the
modulator .
 The control grid has a hole in the front to allow passage of the electron beam .
 The electrons are accelerated and focused on the display .
5

Design of CRT
6

View of CRT
7

Working
 A cathode ray tube (CRT) is a vacuum tube in which electrons emitted from an
electrode are focused onto a phosphorescent screen. The electrons are aimed so
as to create an image on the screen .
8

Cathode Ray Tubes
 Primary output device – Video monitors
 Standard design of video monitor:
Cathode-ray tube (CRT)
9

Display technology of CRT
10

Liquid Crystal Display(LCD)
 Liquid crystals were first discovered in 1888 by Austrian botanist Friedrich
Reinitzer.
 the first experimental LCD made in 1968 .
 Manufacturers have been developing creative variations and improvements since
on LCDs.
 In 1997, manufactures began to offer full size LCD monitors as alternatives to CRT
monitors.
 Until recently, was only used on notebook computers and other portable devices.
11

LCD Technology
 Used for displays in notebooks, small computers, pagers, phones and other
instruments.
 Uses a combination of fluorescent-based backlight, color filters, transistors, and
liquid crystal to create and illuminate images.
 In 1997, manufactures began to offer full size LCD monitors as alternatives to CRT
monitors.
 Until recently, was only used on notebook computers and other portable devices.
 Requires less power as compared to LEDs.
12

View of LCD screens
13

Use of LCD
 Liquid Crystals are used to make thermometers and mood
rings because heat changes absorbance properties.
 Liquid-crystal displays (LCD) commonly used in
small systems
 Liquid crystal, compounds have a crystalline arrangement
of molecules, flow like a liquid
 Passive-matrix LCD
To control light twisting, voltage applied to intersecting conductors to align the molecules
 Active-matrix LCD
Using thin-film transistor technology, place a transistor at
each pixel location
14

Light Emitting Diode(LED)
 LED = a tiny little bulb . small, extremely bright and uses little power.
 Light-Emitting Diode (LED) light up display screen positions based on voltages at
grid intersections.
 Do not have a filament but are illuminated by the movement of electrons in a
semiconductor material.
15

Light Emitting Diode(LED)
 Light emitting diodes are used in LED displays.
 Operation of the LED displays is based on the injection luminescence.
 LED displays are available in many different sizes and shapes.
 Usually LED displays radiate red, orange, yellow or green light.
 They have a wide operating temperature range, are inexpensive, easily interfaced
to digital logic, easily multiplexed, do not require high voltages and have fast
response time.
 The viewing angle is good and display of arbitrary numbers of digits is easily
assembled.
16

World’s Largest LED Display
17

Segment Displays
 A Seven-Segment Display (SSD) is simply a figure eight grouping of
LEDs {some include a decimal point (DP)}.
 Each Segment is labeled (a) thru (g).
 SSDs are available in two configurations
 Common Cathode (all LED cathodes are connected)
 Common Anode (all LED anodes are connected)
a
b
c
d
e
g
dp
f
18

Segment Display Possibilities
Decimal Digits 0-9
Select Alpha Characters
19

View of Segment displays(1/2)
1.Seven Segment Displays
20

View of Segment displays(2/2)
2.16 Segment Displays(Starburst Display)
21

Computer Systems
22

Block Diagram of Digital computer
Encoder CPU Decoder
Memory
Clock
inputs outputs
23

 CPU does all the computations and decisions.it called as a microprocessor.
 The periodic , rectangular signal called Clock , which acts as a timing signal
which is used for sequencing and synchronizing all the operations.
 A written programs are entered into the computer using a key-board and
stored in the part of memory is called as program memory.
 The CPU communicates with outside world through Input and Output
devices.
Definitions
24

Classification of Digital Computers
Digital computer
microcomputers minicomputers maxicomputers
25

Definitions
 Microcomputer is designed to perform vry specific tasks . It is
constructed with minimum number of components.
 Minicomputers are the computers with higher capabilities than
the microcomputers , basically used in business data processing
, industrial control and scientific research.
 Maxi computer is the largest of all types . It is capable of storing
and processing massive amount of data . Basically used in
military . Defence control , banks .
26

Microprocessor
Control unit
ALU Register array
27

Instructions
 ALU carries out all the computation on the data . It performs
arithmetic operations such as addition , subtraction and logic
operations like AND , OR , EX-OR .
 Register array consist of group of registers . These registers are
basically used for a temporary storage of data to be processed .
 Control unit produces all the necessary timing and control
signals for all the operations .
28

Applications of Microprocessor
1. CPU of Computers ,
2. Advanced cars ,
3. Traffic control lights ,
4. Machine tool applications ,
5. Industrial applications .
29

Microcontroller
Memory
CPU
I/O Devices
Peripheral Devices
 A/D Converter
 Timer
 Serial I/O
30

Features of Microcontrollers
1. A microprocessor ranging from a 4 bit to 32 bit processor .
2. Discrete input and outputs lines .
3. Serial input/output ports .
4. Peripherals such as timer , PWM generators , event counters .
5. Volatile memory (RAM) for data storage .
6. Clock generator .
7. A to D converter .
8. In circuit programming and debugging support .
31

Advantage of using Microprocessor and Microcontrollers
1. High accuracy ,precision due to digital nature of data .
2. High reliability .
3. Better performance than analog system .
4. No drifts in the parameter values due to change in temperature .
5. Flexibility due to presence of software .
6. Storage of processed data is possible .
7. The processed data can be suitably displayed .
8. Reduced complexity .
9. Reduced costs .
10. Small size specially with microcontrollers .
32

Memory display devices

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