By:- SUMEET PATEL

Enroll. No. :- 110050111040

VARIOUS DISPLAY DEVICES AND PRINTERS

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Contents

What is Display Device ?

Classification of Display Devices

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Display Devices

A display device is an output device for presentation

of information in visual.

When the input information is supplied as an electrical

signal, the display is called an electronic display.

A display device visually conveys text, graphics, and

video information.

Common applications for electronic visual

displays are televisions or computer monitors.

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Classification

1. Analog display devices (cathode-ray tubes)

• Oscilloscope tubes

• TV CRTs

2. Digital display devices

• LED (including OLED) displays

• VF (vacuum fluorescent ) displays

• LCD (liquid crystal) displays

• Nixie tube displays and PDPs (plasma display panels)

• Electroluminescent displays (ELDs)

3. Others:

• Electronic paper or E paper

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A cathode ray tube (CRT) contains four basic parts:

● Electron gun

● Focusing and accelerating systems

● Deflecting systems

● Evacuated glass envelope with a

phosphorescent screen that glows visibly when

struck by the electron beam.

Analog display devices -cathode-ray tubes

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● 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.

Cathode-ray tubes

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Examples of CRT Devices

CRT TELEVISION CRT MONITOR

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Digital display devices: 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.

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Examples of LED display

LED MONITOR

LED DISPLAY

LED MATRIX

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Vacuum fluorescent displays

Vacuum fluorescent displays are variation on the

triode vacuum tube. The filament of thin, oxide-coated

tungsten is heated enough to emit electrons.

When this emitted electrons strike the phosphor on

the anode, light is produced.

Some displays can show only digits or alphanumeric

characters. They are called segment displays,

because they are composed of several segments that

switch on and off.

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VACUUM FLUORESCENT DISPLAYS

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Liquid crystal displays

LCD are digital passive displays characterised by very

low power consumption and good contrast with

characteristics such a scattering and reflective

configuration.

The heart of all liquid crystal displays (LCDs) is a liquid

crystal itself. A liquid crystal is a substance that flows

like a liquid, but its molecules orient themselves in the

manner of a crystal.

Two liquid crystal materials which are important in

display technology are NEMATIC and CHOLESTERIC

.

Basically LCD comprises of thin layer of nematic liquid

crystal (NLC) fluid, sandwiched between two glass

plates having electrodes, at least one of which is

transparent.

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Nixie tube displays and PDPs (plasma display panels)

A nixie tube is an electronic device for displaying

numerals or other information, in the form of a glass

tube containing multiple cathodes and a wire mesh

anode, filled with neon and often a little mercury and/or

argon at a small fraction of atmospheric pressure.

When electrons in tube collide with gas atoms they

transfer this energy to the atoms, thereby exciting them

into energy levels above the ground state. The atoms

may then lose energy and return to the ground state.

Then the gas emits orange-red light. The ionised gas is

called plasma and gas displays are therefore often

called plasma displays

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Electroluminescent displays (ELDs)

The electroluminescent display is similar in idea to an

ac plasma display, except that the gas-filled area is

replaced by a thin film of electroluminescent material or

Phosphor powder.

When sufficiently large ac voltage (typically 150 to

200 V) is applied between the front and rear electrodes,

the material between them emits light.

The advantages of ELDs include very slim

constructions, high resolution, wide operating

temperature range, and moderate power consumption.

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Electronic paper / e- paper

Electronic paper, also sometimes called e-paper or

electronic ink, is a display technology designed to

mimic the appearance of regular ink on paper.

Electronic paper reflects light like ordinary paper and is

capable of holding text and images indefinitely without

drawing electricity, while allowing the image to be

changed later.

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PRINTERS

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What is PRINTER ?

A printer is an output device that produces text and

graphics on paper.

Many printers are primarily used as local peripherals,

and are attached by a printer cable or a USB cable to a

computer which serves as a document source.

Printers are classified into following types...

1. Impact and non impact printer.

2. Fully formed character and dot matrix

printer.

3. Character at a time and line at a time

printer.

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1. Impact and Non impact printers.

● Impact printers form character on paper by striking

paper with a print head and squeezing inked ribbon

between print head and paper.

● Non impact printers form characters without

engaging the print mechanism with the print surface.

2. Fully formed character and dot matrix printer.

● In fully formed printers characters are embossed in

reverse on the type bars of typewriter. When printed,

all type elements appear connected or fully formed.

● Dot matrix characters are shaped by combinations of

dots that form a group representing a letter or

number viewed together.

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3. Character at a time and line at a time printer.

● Character at time printers print each character

serially and instantly.

● Line at a time printers print each line virtually

instantaneously.

Other types of printers are as follow.

● Dye sublimation printer

● All in one printer

● Photo printer

● Laser printer

● Inkjet printers etc.

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LINE PRINTER

LASER PRINTER

DOTMATRIX PRINTER

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BIBLIOGRAPHY

● Electronic Instrumentation - H S KALSI

● www.google.co.in

● en.wikipedia.org

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ANY QUESTIONS ???

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THANK YOU

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