Interactive Seminar Presentation onDisplay Devices

8/7/2019 Interactive Seminar Presentation onDisplay Devices

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INTERACTIVE STUDY SEMINAR

ON

VIPUL GARG

07-ECE-228


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DISPLAY DEVICE A display device is an output device for presentation ofinformation

invisual ortactile form.

When the input information is supplied as an electrical signal, the

display is called an electronic display.

ELECTRONICDISPLAY

VISUAL

TELEVISION

SETS

COMPUTER

MONITOR

TACTILE

REFRESHABLE

BRAILLE

DISPLAY


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REFRESHABLE BRAILLE DISPLAY

They are usually intended for the blind.

They use electro-mechanical parts to dynamically update a tactileimage (usually of text) by means of raising dots through holes in a flatsurface so that the image (or Braille characters) may be felt by thefingers.

The mechanism which raises the dots

uses the piezo-effect& the software that

controls the display is called a screen reader.


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E-PAPER Unlike conventional backlit flat panel displays, Electronic paper

displays reflect light like ordinary paper.

First developed in the 1970s by Nick Sheridon atXerox's Palo Alto

Research centre.

Gyricon: consisted of polyethylene spheres each being a dipole,

embedded in a transparent silicone sheet & suspended in oil Electrophoretic Display: forms visible images by rearranging charged

pigment particles using an applied electric field.


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Electro wetting: Based on controlling the shape of a confined

water/oil interface by an applied voltage. Switching between white andcolored reflection is fast enough to display video content.

Interferometric modulator display: Technology that can create

various colors through the interference of reflected light.

Electronic ink can be applied to flexible or rigid materials.

E-Paper is being used in digital schoolbooks, Wristwatches,

Displays embedded in smart cards, Low cost Mobile

phones.


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TOUCH SCREEN DISPLAY An electronic visual displaythat can detect the presence and location

of a touch within the display area.

There are a variety of touch screen technologies:

Resistive touch screen: composed of several layers, the mostimportant of which are two thin, electrically conductive layersseparated by a narrow gap.

Surface acoustic wave: uses ultrasonicwaves that pass over the

touch screen panel.


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Capacitive sensing: As the human body is also an electrical

conductor, touching the surface of the screen is measurable as a

change in capacitance.

Infrared: uses an array of X-Y infrared LED & Photo-detectorpairs

around the edges of the screen to detect a disruption in the patternof LED beams.

Optical Imaging: two or more image sensors are placed around the

edges of the screen. Infrared back lights are placed in the camera's

field of view on the other side of the screen.


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Dispersive SignalTechnology : Introduced in 2002 by 3M, this

system uses piezoelectric sensors located at various positions around

the screen to detect the mechanical energy in the glass that occurs due

to a touch. A downside is that after the initial touch the system cannot

detect a motionless finger.

Acoustic Pulse Recognition: Introduced byTyco Internationals Elo

division in 2006, uses the same principle as Dispersive Signal

Technology.


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LIQUID CRYSTAL DISPLAY A thin, flat display that uses the light modulating properties ofliquid

crystals (LCs).

Each pixel of an LCD typically consists of a layer of molecules aligned

between two transparent electrodes, and two polarizing filters, the axes

of transmission of which are perpendicular to each other.


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When a large number of pixels are needed, instead of driving each

directly, the display is multiplexed.

LCD panels produce no light of their own, they require an external

lighting mechanism (cold cathode fluorescent lamp) to be easily visible.

Passive-matrix LCD:They are usually not backlit. The pixel retains its

state between refreshes without the benefit of a steady electrical

charge.

Active-matrix LCD: They are always backlit. Used in High-resolution

color displays. A matrix ofTFTs is added to the polarizing and color

filters. Each pixel has its own dedicated transistor.


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Twisted nematic field effect: Contains liquid crystal elements whichtwist and untwist in proportion to the voltage applied at varying degreesto allow light to pass through.

In-plane switching: The technology which aligns the liquid crystal cells

in a horizontal direction.


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Advanced Fringe Field Switching: It improves upon the IPShorizontally aligned field by creating an electric fringe maximizing

transmittance efficiency and wide viewing angle.

Fringe Field structure enables a greater amount of light to passthrough the liquid crystal layer to ensure improved visual performance

and reduced power consumption.


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PLASMA DISPLAY

Called "plasma" displays because the technology utilizes small cells

containingelectrically charged ionized gases. These are bright (1,000 luxor higher), have a wide colorgamut, and can

be produced in fairly large sizes(up to 150 inches).


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A panel is an array of millions of tinycells between two panels of glass.

These "cells", hold a mixture of noble gases and a minuscule amount

ofmercury. When the mercury is vaporized and a voltage is applied

across the cell, the gas in the cells form a plasma.

In color panels, the back of each cell is coated with a phosphor& cells

are luminous when they are electrified through "electrodes.

Everypixel is made up of three separate sub-pixel cells, each with

different colored phosphors.

Plasma display screens are made

from glass, which reflects more

light than the material used tomake an LCD screen.


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LASER VIDEODISPLAY It utilizes two or more individually modulated optical (laser) rays of

different colors to produce a combined spot that is scanned and

projected across the image plane by a polygon-mirror system or less

effectively by optoelectronic means to produce a color-television

display.

Maintains full power output for the lifespan of the laser; the picture

quality wont degrade.

Have a very wide color gamut, which can produce up to 90% of the

colors a human eye can perceive.

Capable of displaying 3D stereoscopic video.


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3-DDISPLAY ItConveys a stereoscopic perception of 3-D depth to the viewer.

There are various types/technologies of 3-D display that are shown as

follows:


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Stereoscopic: Technique of creating the illusion of depth in an image by

presenting two offset images separately to the left and right eye of the

viewer. Both of these 2-D offset images are then combined in the brain

to give the perception of 3-D depth.

Auto stereoscopic:A method of displaying stereoscopic images w/o

the use of special headgear. The optics splits the images directionally

into the viewer's eyes, so the display viewing geometry requires limited

head positions that will achieve the stereoscopic effect.

Parallax-barrier: consists of a layer of material

with a series of precision slits, allowing each eye

to see a different set of pixels, creating a sense

of depth through parallax. Lenticular display: an array of magnifying lenses,

designed so that when viewed from slightly different

angles, different images are magnified to give an

illusion of depth.


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AMOLEDDISPLAY Consists of a matrix of OLED pixels that generate light upon electrical

activation that have been deposited or integrated onto a TFTarray,

which functions as a series of switches to control the current flowing to

each individual pixel.

OLED is a LED in which the emissive layer is a film oforganic

compoundswhich emit light in response to an electric current. This

layer of organic semiconductor material is situated between two

electrodes.

OLED display functions without a backlight. In low ambient light

conditions, it can achieve a higher contrast ratio than an LCD using

eithercold cathode fluorescent lamps orLED backlight.


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A typical OLED is composed of a layer of organic materials situatedbetween two electrodes, the anode and cathode. The organic moleculesare electrically conductive. These materials have conductivity levels

ranging from insulators to conductors, and therefore are consideredorganic semiconductors.

Organic semiconductor is an organic materialwith semiconductorproperties. Polycyclic aromatic compounds include pentacene,anthracene, and rubrene. Polymeric organic semiconductors include

poly(3-hexylthiophene), poly(p-phenylene vinylene).

LEDDISPLAY TV There are two types of LED panels: conventional (using discrete LEDs)

and surface-mounted device (SMD) panels.

A cluster of red, green, and blue diodes is driven together to form a full-colorpixel, usually square in shape. These pixels are spaced evenlyapart and are measured from center to center for absolute pixelresolution.

The largest LED display in the world is over 1,500 ft (457.2 m).


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Interactive Seminar Presentation onDisplay Devices

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