Fed Seminar Report

1SEMINAR REPORT

SEMINAR REPORT

ON

FIELD EMISSION DIAPLAY

Done By

MAHESH M M

DIPLOMA IN ELECTRONICS AND COMMUNICATION

DEPARTMENT OF ELECTRONICS AND COMMUNICATION

GOVERNMENT POLYTECHNIC COLLEGE

NEYYATTINKARA

2017

G P T C NTA ELECTRONICS & COMMUNICATION

2SEMINAR REPORT

SEMINAR REPORT

ON

FIELD EMISSION DIAPLAY

Done By

MAHESH M M

DIPLOMA IN ELECTRONICS AND COMMUNICATION



NEYYATTINKARA

2017


3SEMINAR REPORT



NEYYATTINKARA

2017

Certificate

This is to certify that this seminar report is a bonafide record of the work done by

MAHESH M M under our guidance towards the partial fulfillment of the requirement

for the award of Diploma in Electronics and Communication Engineering of the

Department of Technical Education, Kerala during the year 2017

Guided By, Sri. Sulficar A

Sri. Divya.C HOD

Lecturer Electronics and communication


4SEMINAR REPORT

ACKNOWLEDGEMENT

I take this opportunity to express our sincere gratitude and profound obligation to Sri. Sulficar

A, Head Of Department of Electronics and Communication Engineering, Government polytechnic

College Neyyattinkara.

I also wish to express my gratitude to Sri. Aravind Sekhar R, Sri. Pavitrakumar G, Smt. Reeya

George, Smt. Divya C for their help and encouragement done throughout this work.

Last but not the least, I am extremely grateful to all our friends without whose timely aid,

could not have completed the work successfully.

MAHESH M M

(Reg.no: 14200156)


5SEMINAR REPORT

ABSTRACT

A field emission display (FED) is a flat panel display technology that uses large-area

field electron emission sources to provide electrons that strike colored phosphor to produce a

color image. In a general sense, an FED consists of a matrix of cathode ray tubes, each tube

producing a single sub-pixel, grouped in threes to form red-green-blue (RGB) pixels. FEDs

combine the advantages of CRTs, namely their high contrast levels and very fast response

times, with the packaging advantages of LCD and other flat panel technologies. They also

offer the possibility of requiring less power, about half that of an LCD system.

Sony was the major proponent of the FED design and put considerable research and

development effort into the system during the 2000s. Sony's FED efforts started winding

down in 2009 as LCD became the dominant flat panel technology. In January 2010, AU

Optronics announced that it acquired essential FED assets from Sony and intends to continue

development of the technology. As of 2016, no large-scale commercial FED production has

been undertaken.

FEDs are closely related to another developing display technology, the surface-

conduction electron-emitter display, or SED, differing primarily in details of the electron

emission system.


https://en.wikipedia.org/wiki/Surface-conduction_electron-emitter_display

https://en.wikipedia.org/wiki/Surface-conduction_electron-emitter_display

https://en.wikipedia.org/wiki/AU_Optronics

https://en.wikipedia.org/wiki/AU_Optronics

https://en.wikipedia.org/wiki/Sony

https://en.wikipedia.org/wiki/LCD

https://en.wikipedia.org/wiki/Pixel

https://en.wikipedia.org/wiki/Cathode_ray_tube

https://en.wikipedia.org/wiki/Phosphor

https://en.wikipedia.org/wiki/Field_electron_emission

https://en.wikipedia.org/wiki/Flat_panel_display

6SEMINAR REPORT

CONTENT

INTRODUCTION………………………………………………..…......8

MODULE – 1

HISTORY& EVOLUTION OF DISPLY……………………..…….…..10

1.1 CATHODE RAY TUBE (CRT) DISPLY……………………11

1.2 LIQUID CRYSTAL DISPLAYS (LCD)………………………..13

1.3 PLASMA DISPLAY PANEL (PDP)……………………...........15

1.4 LIGHT EMITTING DIODE (LED) DISPLAY..........................16

1.5 OLED DISPLAYS……………………………………………...18

1.6 FIELD EMISSION DISPLAYS………………………………...19

MODULE – II

TECHNOLOGY AND WORKING…………………………………...20

2.1 THE FOLLOWER NORDHEIM LAW………………………..20

2.2 FED TECHNOLOGY………………………………………….21

2.3 WORKING……………………………………………………..28

MODULE - III

FED CHARATERISTICS…………………………………………….30

3.1 FED CHARACTERISTICS……………………………….……30


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MODULE – IV

ADVANTAGES & DISADVANTAGES……………………………33

4.1 ADVANTAGES………………………………………………..33

4.2 DISADVANTAGES……………………………………………34

4.3 APPLICATIONS……………………………………….………35

CONCLUSIONS………………………………………….……….36

REFERENCE………………………………………………...……37


8SEMINAR REPORT

INTRODUCTION

Various types of displays have become common in the everyday life. The displays are used in

televisions, computers, mobile phones etc. They also have wide use in laboratories, military

applications and in medical applications. The displays are those devices by which we can

view moving objects. The displays are manufactured depending upon their application. One

of the hottest markets driving physics research is the demand for a perfect visual display.

People want, for example, large, thin, lightweight screens for highdefinition TV and very

high resolution flat computer monitors that are robust and use little power. Several types of

flat display are competing for these applications. Not surprisingly, the research departments

of universities and the big electronics companies around the world are bustling with exciting

ideas and developments. New university spinout companies are developing many new

devices.

The flat panel display (FPD) market is one of the largest consumer electronic sectors. There

are many competing FPD technologies with active matrix liquid crystal displays (AMLCDs)

leading the way. For the larger flat displays, plasma display panels (PDPs) dominate;

however, recent developments by Samsung have seen the emergence of AMLCDs with 52

inch diagonal screens. Samsung have also produced a prototype 38 inch full colour video rate

carbon nanotube (CNT) display which shows all the positive attributes associated with field

emission such as high brightness, high contrast, excellent viewing angles, low power

consumption and large area. Other field emission display (FED) technologies based on metal

Spindt tips favoured by companies such as Candescent, Pixtech and Motorola have all

delivered high quality displays. The UK based company, Printable Field Emitters, has opted

for a screen printed graphitesilicon dioxide binder cathode to make their large area displays.

Canon, Toshiba, Noritake, MEW and Sony all have

Their own field emission (FE) based technologies currently being developed for di erentff

segments of the market in this fast moving sector. All these companies see the merits

associated with having a fully scalable FED technology, but need the cost of production to be

lowered in order to enter the consumer market. Other emerging display technologies vying

for honors in this sector include polymer and organic light emitting diodes (OLEDs), with no

one technology being able to show all the attributes needed for a high quality large flat

display that can be produced at a suitable cost and scale.


9SEMINAR REPORT

FEDs operate in a manner which is a hybrid of the AMLCD and the PDP. The addressing of

the picture elements is based on the matrix address system developed for AMLCDs, with the

emissive display component showing similarities to the PDP output. Hundreds of multiple

gated matrix addressed field emission cathodes emit electrons that hit a single pixel, whose

brightness to a first order is controlled by the acceleration voltage applied between the

cathode and the phosphor anode. The key physical parameters of importance in selecting a

suitable cathode material for such an application is, in addition to its longevity, robustness

and an ability to readily integrate into a production process, the requirement of being able to

source high current densities at relatively low electric fields. In addition, an ability to produce

uniform electron emission currentvoltage characteristics with little or no hysteresis is also

required. This tightness of the electron emission curves with applied field is important in

being able to design matrix driver strategies with the required precision, where suitable o setff

voltages can be used for turning on gated cathodes. In terms of phosphors, standard high and

medium voltage phosphors are at present preferred over the low voltage variety due to the

reliability and testing that has been performed in both the CRT arena and plasma displays.


10SEMINAR REPORT

MODULE - I

HISTORY & EVOLUTION OF DISPLAY

It has taken more than three decades for field emission displays (FEDs) to go from

idea to commercial product. In 1968, Charles A. ”Capp” Spindt at the Stanford Research

Institute (now called SRI International) had the idea of fabricating a flat display using

microscopic molybdenum cones singly or in arrays (FEAs). This development was the

enabling technology the concept for using FEAs in a matrix addressed display (FED)

conceived by the SRI team of which Capp was a member, and patented by Crost, Shoulders

and Zinn in 1970 (US Patent 3,500,102). Laboratoired’Electronique de Technologieet de

l’Informatique (LETI), a research arm of the French Atomic Energy Commission, in

Grenoble. LETI picked up on the technology and publicly demonstrated an operating display

in 1985. The SRI (Stanford Research Institute) team was finally funded by Boeing and

Commtech International (a venture capital patnership) to develop a full colour display and

was able to demonstrate the first color FED in 1987.


11SEMINAR REPORT

1.1 CATHODE RAY TUBE (CRT) DISPLAY

Fig: CRT Display.

A cathode-ray tube, often called a CRT, is an electronic display device in which a

beam of electrons can be focused on a phosphorescent viewing screen and rapidly varied in

position and intensity to produce an image. A CRT consists of three basic parts: the electron

gun assembly, the phosphor viewing surface, and the glass envelope. The electron gun

assembly consists of a heated metal cathode surrounded by a metal anode. Electrons from the

cathode flow through a small hole in the anode to produce a beam of electrons. The electron


12SEMINAR REPORT

gun also contains electrical coils or plates which accelerate, focus, and deflect the electron

beam to strike the phosphor viewing surface in a rapid side-to-side scanning motion starting

at the top of the surface and working down. The phosphor viewing surface is a thin layer of

material which emits visible light when struck by the electron beam. The chemical

composition of the phosphor can be altered to produce the colours white, blue, yellow, green,

or red. The glass envelope consists of a relatively flat face plate, a funnel section, and a neck

section. The phosphor viewing surface is deposited on the inside of the glass face plate, and

the electron gun assembly is sealed into the glass neck at the opposite end. The purpose of the

funnel is to space the electron gun at the proper distance from the face plate and to hold the

glass envelope together so that a vacuum can be achieved inside the finished tube.

The CRT used in a color television or color computer monitor has a few additional

parts. Instead of one electron gun there are three - one for the red color signal, one for blue,

and one for green. There are also three di erent phosphor materials used on the viewingff

surface again, one for each color. These phosphors are deposited in the form of very small

dots in a repeated pattern across the screenred, blue, green, red, blue, green, and so on. The

key to a color CRT is a piece of perforated metal, known as the shadow mask, which is

placed between the electron guns and the viewing screen. The perforations in the shadow

mask are aligned so that the red gun can fire electrons at only the phosphor dots which

produce the red color, the blue gun at the blue dots, and the green gun at the green dots. By

controlling the intensity of the beam for each color as it scans across the screen, di erentff

colors can be produced on di erent areas of the screen, thus producing a color image.ff


13SEMINAR REPORT

1.2 LIQUID CRYSTAL DISPLAYS (LCD)

A liquid crystal display (LCD) is a flat panel display, electronic visual display, or

video display that uses the light modulating properties of liquid crystals (LCs). LCs dont emit

light directly. They are used in a wide range of applications, including computer monitors,

television, instrument panels, aircraft cockpit displays, signage, etc. They are common in

consumer devices such as video players, gaming devices, clocks, watches, calculators, and

telephones. LCDs have replaced cathode ray tube (CRT) displays in most applications. They

are available in a wider range of screen sizes than CRT and plasma displays, and since they

do not use phosphors, they cannot suffer image burn-in. LCDs are more energy e cient andffi

o er safer disposal than CRTs. Its low electrical power consumption enables it to be used inff

battery-powered electronic equipment. It is an electronically modulated optical device made

up of any number of segments filled with liquid crystals and arrayed in front of a light source

(backlight) or reflector to produce images in color or monochrome. The most flexible ones


14SEMINAR REPORT

use an array of small pixels. The earliest discovery leading to the development of LCD

technology, the discovery of liquid crystals, dates from 1888. By 2008, worldwide sales of

televisions with LCD screens had surpassed the sale of CRT units.

Even the liquid crystal display (LCD), which has 85 per cent of the flatscreen market,

is still a young technology and the subject of very active research. LCDs depend on arrays of

cells (pixels) containing a thin layer of molecules which naturally line up (liquid crystals);

their orientation can be altered by applying a voltage so as to control the amount of light

passing through. Their main drawbacks have been poor viewing characteristics when seen

from the side and in bright light, and a switching speed too slow for video. Electrically

sensitive materials called ferroelectric and antiferroelectric liquid crystals show potential.

These work slightly di erently and are bistable so should use less power. They can respondff

100 to 1000 times faster than current displays, and should give brighter images from all

angles. One solution to the drawbacks of LCDs is to combine them with another technology.

Indeed, the latest, high quality LCDs on the market incorporates a tiny electronic switch (a

thin film transistor, TFT) in each pixel to drive the display.


15SEMINAR REPORT

1.3 PLASMA DISPLAY PANEL (PDP)

Fig: Plasma Display Panel

A plasma display panel (PDP) is a type of flat panel display common to large TV

displays 30 inches (76 cm) or larger. They are called ”plasma” displays because the

technology utilizes small cells containing electrically charged ionized gases, or what are in

essence chambers more commonly known as fluorescent lamps. Plasma displays are bright

(1,000 lux or higher for the module), have a wide color gamut, and can be produced in fairly

large sizes up to 150 inches (3.8 m) diagonally. They have a very low-luminance ”dark-

room” black level compared to the lighter grey of the unilluminated parts of an LCD screen

(i.e. the blacks are blacker on plasmas and greyer on LCDs). The display panel itself is about

6 cm (2.5 inches) thick, generally allowing the device’s total thickness (including electronics)

to be less than 10 cm (4 inches). Plasma displays use as much power per square meter as a

CRT or an AMLCD television. Power consumption varies greatly with picture content, with

bright scenes drawing significantly more power than darker ones this is also true for CRTs.

Typical power consumption is 400 watts for a 50-inch (127 cm) screen.


16SEMINAR REPORT

The lifetime of the latest generation of plasma displays is estimated at 100,000 hours

of actual display time, or 27 years at 10 hours per day. This is the estimated time over which

maximum picture brightness degrades to half the original value. Plasma display screens are

made from glass, which reflects more light than the material used to make an LCD screen.

This causes glare from reflected objects in the viewing area. Companies such as Panasonic

coat their newer plasma screens with an anti-glare filter material. Currently, plasma panels

cannot be economically manufactured in screen sizes smaller than 32 inches. Although a few

companies have been able to make plasma Enhanced-definition televisions (EDTV) this

small, even fewer have made 32in plasma HDTVs. With the trend toward large-screen

television technology, the 32in screen size is rapidly disappearing. Though considered bulky

and thick compared to their LCD counterparts, some sets such as Panasonic’s Z1 and

Samsung’s B860 series are as slim as one inch thick making them comparable to LCDs in

this respect.

1.4 LIGHT EMITTING DIODE (LED) DISPLAY

Fig: Light Emitting Diode Display.


17SEMINAR REPORT

An LED display is a flat panel display, which uses light-emitting diodes as a video

display. A LED panel is a small display, or a component of a larger display. An LED-

backlight LCD television is an LCD television, flat panel display that uses LED backlighting

instead of the Cold cathode (CCFL) used in traditional LCD televisions. The use of LED

backlighting has a dramatic impact, resulting in a thinner panel, less power consumption and

better heat dissipation, and a brighter display with better contrast levels. The LEDs can come

in three forms: 1. Dynamic RGB LEDs which are positioned behind the panel. 2. White

Edge-LEDs positioned around the rim of the screen using a special di usion panel to spreadff

the light evenly behind the screen (the most common). 3.A full-array of LEDS which are

arranged behind the screen but are incapable of dimming or brightening individually.

1.4.1 RGB DYNAMIC LEDS

This method of backlighting allows dimming to occur in locally specific areas of

darkness on the screen. This can show truer blacks, whites and PRs at much higher dynamic

contrast ratios, at the cost of less detail in small, bright objects on a dark background, such as

star fields.

1.4.2 EDGE-LEDS

This method of backlighting allows for LED-backlit TVs to become extremely thin.

The light is di used across the screen by a special panel which produces a uniformff

brightness distribution across the screen.


18SEMINAR REPORT

1.4.3 FULL ARRAY LEDS

Full-array backlighting, on the other hand, gives the entire screen surface a series of

LED backlights. This allows each LED to be turned on and o in the screen for betterff

control. Full-array has thicker panels than edge lighting.

1.5 OLED DISPLAYS

Fig: Organic Light-Emitting Diode Display.

An OLED (organic light-emitting diode) is a light-emitting diode (LED) in which the

emissive electroluminescent layer is a film of organic compounds which emit light in

response to an electric current. This layer of organic semiconductor material is situated

between two electrodes. Generally, at least one of these electrodes is transparent. There are

two main families of OLEDs: those based on small molecules and those employing polymers.

Adding mobile ions to an OLED creates a Light-emitting Electrochemical Cell or LEC,

which has a slightly di erent mode of operation. OLED displays can use either passive-ffmatrix (PMOLED) or active-matrix addressing schemes. Active-matrix OLEDs (AMOLED)

require a thin-film transistor backplane to switch each individual pixel on or o , but allow forff

higher resolution and larger display sizes. An OLED display works without a backlight. Thus,

it can display deep black levels and can be thinner and lighter than liquid crystal displays

(LCDs). In low ambient light conditions such as dark rooms an OLED screen can achieve a

higher contrast ratio than an LCD, whether the LCD uses either cold cathode fluorescent

lamps or the more recently developed LED backlight. Due to their low thermal conductivity,


19SEMINAR REPORT

they typically emit less light per area than inorganic LEDs. OLEDs are used in television set

screens, computer monitors, small, portable system screens such as mobile phones and PDAs,

watches, advertising, information, and indication. OLEDs are also used in large-area light-

emitting elements for general illumination.

1.6 FIELD EMISSION DISPLAYS

The other major technology competing for the flat screen, market is the field emission

display. A field emission display (FED) is a display technology that incorporates flat panel

display technology that uses large-area field electron emission sources to provide electrons

that strike colored phosphor to produce a color image as a electronic visual display. In a

general sense, a FED consists of a matrix of cathode ray tubes, each tube producing a single

sub-pixel, grouped in threes to form red-green-blue (RGB) pixels. FEDs combine the

advantages of CRTs, namely their high contrast levels and very fast response times, with the

packaging advantages of LCD and other flat panel technologies. They also o er theff

possibility of requiring less power, about half that of an LCD system.


20SEMINAR REPORT

MODULE 2

TECHNOLOGY AND WORKING

2.1 THE FOWLER NORDHEIM LAW

The Fowler-Nordheim Law explaining field emission as a quantum e ect became theff

basis for research on FEDs. A potential barrier at the surface of a metallic conductor called

the ”work function” binds electrons to the material. For an electron to leave the material, the

electron must gain an energy which exceeds the work function. This can be accomplished in a

variety of ways, including thermal excitation (thermionic emission), electron and ionic

bombardment (secondary emission), and the absorption of photons (photoelectric e ect).ff

Fowler-Nordheim emission or field emission di ers from these other forms of emission inff

that the emitted electrons do not gain an energy which exceeds the material work function.

Fig: Tunneling

Field emission occurs when an externally applied electric field at the material surface

thins the potential barrier to the point where electron tunneling occurs, and thus di ersff

greatly from thermionic emission. Since there is no heat involved, field emitters are a ”cold

cathode” electron source.


21SEMINAR REPORT

2.2.1 FED TECHNOLOGY

The FED screen mainly contains three parts: 1. Low-voltage phosphors. 2. A field

emission cathode using a thin carbon sheet as an edge emitter. 3. FED packaging, including

sealing and vacuum processing

.

Fig: Inside The Display.


22SEMINAR REPORT

Fig: Technology

LOW VOLTAGE PHOSPHORS

The low voltage phosphors are the screens in which the images are displayed. In the

display technology the phosphor screens act as anode, which receives the electrons emitted

from the cathode. The phosphor glows when the electrons bombards with it to show the

images. The phosphors are made up of layers of three primary colours -green, red and blue.

These colour phosphors are displayed by the field sequential colour in which the green

information is read first then redrawn with red information and finally with blue colour. The

FED may have pixel pitches of about 0.2mm.


23SEMINAR REPORT

FIELD EMISSION CATHODE

In the field emission display screen the cathodes are electron guns that emit electrons.

Here there are about 200-million electron guns called micro tips. The emission of electrons is

called cold cathode emission. Each of these micro tips is smaller than one micrometer and

they are deposited into a dense grid. They are made up of materials such as molybdenum. The

micro tips can be of di erent types:ff

1. Wedge type emitter using silicon.

2. Silicon tips with continuous coating of diamond particles.

3. Single-crystal diamond particle on silicon tips.

4. Planar diode emitter.

5. Metal-insulator-semiconductor type planar emitter

Wedge type emitter using silicon:


24SEMINAR REPORT

The outstanding features of wedge type emitter using silicon are its brightness and low

vacuum requirements. It has a packaging density of 106 emitters per mm2 at the rate of 103

emitters per pixel. It has an accelerating electrode potential of 40V and low power

consumption. However this display has to go miles in the case of price and mass production

status.

Silicon tips with continuous coating of diamond particles:

These cone-shaped blunt emitters have radii of curvature ranging from 0.3 to 3 pm.

The low work function can o er considerable current at low voltage field emission.ff


25SEMINAR REPORT

Single-crystal diamond particle on silicon tips:

Instead of plating the polycrystalline diamond particles on silicon tips, diamond

particles can be placed on the tips of silicon needle to form a field emitter. The only drawback

is the expenditure involved in placing diamond particles on the tips of silicon needle.

Planar diode emitter:


26SEMINAR REPORT

The planar diode emitter configuration uses a diamond like carbon emitter. They are

easy to fabricate and much suited for mass production. One disadvantage for this type of

displays is that once failed, the display will have to work without that pixel.

Metal-insulator-semiconductor type planar emitter:

A new type of field emission display (FED) based on an edge-enhance electron

emission from metal-insulator-semiconductor (MIS) thin film structure is proposed. The

electrons produced by an avalanche breakdown in the semiconductor near the edge of a top

metal electrode are initially injected to the thin film of an insulator with a negative electron

a nity (NEA), and then are injected into vacuum in proximity to the top electrode edge. Theffi

condition for the deep-depletion breakdown near the edge of the top metal electrode is

analytically found in terms of ratio of the insulator thickness to the maximum (breakdown)

width of the semiconductor depletion region: this ratio should be less than 2 3 π−2 = 0.27.

The influence of a neighboring metal electrode and an electrode thickness on this condition


27SEMINAR REPORT

are analyzed. Di erent practical schemes of the proposed display with a special reference toff

M/CaF2/Si structure are considered.

2.2.2 .FED PACKAGING

The field emission display screens are comprised of a thin sandwich. In this the back

is a sheet of glass or silicon that contains millions of tiny field emitters which is the cathode.

The front is a sheet of glass coated with phosphor dots, which is the anode. The anode and

cathode are a fraction of millimeter apart. Field emission is the extraction of electrons from a

surface under the influence of an applied electric field. The front surface potential barrier for

electron emission is reduced by the application of voltage Va to an anode located at a

distance D away. Far from the emitter surface the macroscopic field is simply Va/D. For tip

based structures this macroscopic field is enhanced in the neighborhood of an emitter by a

geometric field enhancement factor beta. This results in a local electric field which is larger

than the applied field. The most common definition of the field enhancement factor beta is the

ratio of the local field to the applied field. In the case of an isolated vertically aligned CNT in

the electrode geometry presented in figure, the local field depends on the height h, radius r

and anode substrate separation D.


28SEMINAR REPORT

2.3 WORKING

As a result care must be taken in analyzing FE measurements on electrode geometries

similar to the one described in figure to ensure that the anode is su ciently far away from theffi

emitter for this e ect to be ignored. The discussion above is based on a single isolatedff

emitter. When there are a large number of emitters nearby screening of the applied field can

occur.

A high voltage-gradient field is created between the emitters and a metal mesh

suspended above them, pulling electrons o the tips of the emitters. This is a highly non-fflinear process and small changes in voltage will quickly cause the number of emitted

electrons to saturate. The grid can be individually addressed but only the emitters located at

the crossing points of the powered cathode and gate lines will have enough power to produce

a visible spot, and any power leaks to surrounding elements will not be visible. The non-

linearity of the process allows avoidance of active matrix addressing schemes once the pixel

lights up, it will naturally glow for some time. Non-linearity also means that the brightness of

thesub-pixelpulse-width


29SEMINAR REPORT

Fig: Working

modulated to control the number of electrons being produced, like in plasma displays. The

grid voltage sends the electrons flowing into the open area between the emitters at the back

and the screen at the front of the display, where a second accelerating voltage additionally

accelerates them towards the screen, giving them enough energy to light the phosphors. Since

the electrons from any single emitter are fired toward a single sub-pixel, the scanning

electromagnets are not needed.


30SEMINAR REPORT

MODULE 3

FED CHARACTERISTICS

3.1 FED CHARATERISTICS

In the world of miniaturization, Cathode ray tube (CRT) is giant dinosaurs waiting for

extinction. A CRT uses a single-point hot electron source that is scanned across the screen to

produce an image. Comparing with the other displays the field emission displays has many

advantages. They are:

1. Brightness.

2. Speed.

3. Compact and lightweight.

4. Display size.

5. Low driving voltage.

6. Wider viewing angle.

7. High illumination.

8. Wide temperature extremes.

9. Colour Quality

3.1 .1 BRIGHTNESS

Most displays are adequate in normal room lighting. However, in dimly lit situations,

such as a patient bedside at night, dim (reflective) displays are di cult to read. Mostffi

alarming, a dim display may be deceptively easy to misread. Because an FED is an emissive

display that produces its own light, it can be dimmed continuously from full brightness to less

than 0.05 fL. In direct sunlight applications there will be a problem of low contrast. This


31SEMINAR REPORT

often requires the use of special contrast enhancement filters, such as 3M micro louver filters

to generate contrast.

3.1.2 SPEED

Display speed is the rate at which the image can be changed while maintaining image

detail. Displays with inadequate response times will create image ”smear” that can be

confused with defective blood flow, or will hide jitter that can indicate instability or electrical

interference. With a response time of 20 nanoseconds, FED technology produces smear-free

video images.

3.1.3 COMPACT AND LIGHTWEIGHT FLAT PANEL DISPLAYS

Far less bulky than the CRT or plasma emission based displays, and are also significantly

brighter than back lit LCDs.

3.1.4 DISPLAY SIZE

This technology could produce a ordable large displays in the 20 to 40-inch diagonalff

range suitable for TVs.

3.1.5 LOW DRIVING VOLTAGE

As discussed earlier the field emission displays can be made to work in extremely low

voltage conditions with some limitations.


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3.1.6 WIDER VIEWING ANGLE

A main advantage of the field emission display screens when compared with the ordinary

cathode ray tube display is its wider viewing angles. The FED s can attain a viewing angle of

1600.

3.1.7 HIGH ILLUMINATION

The FED glows by itself by the bombarding of the electrons on the phosphor screen. So

the FEDs can attain high illumination.

3.1.8 WIDE TEMPERATURE EXTREMES

Unlike CRTs, FEDs have no cathode heater, no deflection system, and no shadow mask.

Because of the cold cathode emission, instant-on is available at wide temperature extremes.

3.1.9 COLOUR QUALITY

FEDs use conventional TV phosphors. This is of particular importance in such areas as

telemedicine. The ability of a display to show true flesh tones depends in large part on the

colorimetry of the display. TV phosphors have been fine-tuned for decades to provide the

most natural skin tones possible, and, although not yet widely used, are unchanged in some

FEDs.

FED technology provides a wide color gamut with continuous dimming and 8-bit gray

scale. Its image is equally bright from any viewing angle, and power e ciency is high (fromffi

3 to 40 lm/W, depending on voltage and phosphor).


33SEMINAR REPORT

MODULE - IV

ADVANTAGES AND DISADVANTAGES

4.1 ADVANTAGES

1. Far less bulky than the CRT or plasma emission based displays less than 1 10th the

thickness and weight.

2. Lower power and more rugged.

3. No non-linearities or color errors.

4. Viewable from any angle with no change in brightness, contrast or color.

5. Wider operating temperature range Usable from -40C to 85 C with no change in

performance.

6. Brighter than back lit LCDs and potentially lower power consumption than LCDs.

7. Larger viewing angle.

8. Sunlight readability.

9. Potentially lower manufacturing costs fewer processing steps than Active Matrix LCDs.


34SEMINAR REPORT

4.2 DISADVANTAGES

1. The e ciency of the field emitters is based on the extremely small radii of the tips, but thisffi

small size renders the cathodes susceptible

to damage by ion impact. The ions are produced by the high voltages interacting with residual

gas molecules inside the device.

2. FED display requires a vacuum to operate, so the display tube has to be sealed and

mechanically robust. However, since the distance between the emitters and phosphors is quite

small, generally a few millimeters, the screen can be mechanically reinforced by placing

spacer strips or posts between the front and back face of the tube.

3. FEDs require high vacuum levels which are di cult to attain: the vacuum suitable forffi

conventional CRTs and vacuum tubes is not su cient for long term FED operation. Intenseffi

electron bombardment of the phosphor layer will also release gas during use.

4. Cathode Destruction due to Uncontrolled Emission (arcing).

Fig: E ects of arcing.ff

5. Manufacturers are at present unable to compete with LCDs and plasma displays on a cost

basis.


35SEMINAR REPORT

4.3 APPLICATIONS

Field emission displays (FEDs) are used in different devices replacing other displays.

Sonographs

X-ray imaging devices

Heart rate monitor

Laptop computers

Hang-on-the wall televisions

Big screen and PC monitors

High-definition TV.


36SEMINAR REPORT

CONCLUSION

CRT technology has already reached its technological and marketing limits and will

likely be replaced in recent years. The modern world needs substances that are small in size.

These show that the cathode ray tube do not have much to do anything in the market in

future. And it would die already, if Field Emission Display (FED) technology or any other

displays would bring anything to the market. In particular, it is widely believed that carbon

nanotubes will take electronic devices to the next level. Many people expect the hugely

popular LCD and plasma screens of today to be replaced by field emission flat screen

displays (FED-TV). FED-TVs take all the best aspects of CRTs, LCDs and plasma TVs and

roll them into a single package. While the technology exists, manufacturers are at present

unable to compete with LCDs and plasma displays on a cost basis. However, carbon

nanotubes have the ability to change all that.


37SEMINAR REPORT

REFERENCE

Serkan Toto, "FED: Sony calls it quits, basically burying the technology as a whole", CrunchGear, 31 Mar 2009

http://www.digitimes.com/news/a20100121PD207.html Richard Fink, "A closer look at SED, FED technologies", EE Tines-Asia, August

16–31, 2007, pp. 1–4 Light emitting principle of an FED system by SHARP Archived June 16, 2006, at

the Wayback Machine. "FED". Meko, Ltd. 22 November 2006. Archived from the original on 2006-08-20.

Retrieved 2006-11-27.> "SED". Meko, Ltd. 22 November 2006. Archived from the original on 2006-08-20.

Retrieved 2006-11-27. Jerry Ascierto, "Candescent Delays Plant, Replaces CEO", Electronic News, 1

March 1999 "Candescent Technologies Files Chapter 11 and Announces a Sale of Its Assets",

Business Wire, 23 June 2004 "Arrowhead Subsidiary, Unidym, to Merge with Carbon Nanotechnologies",

nanotechwire, 23 March 2007 "Sony to Debut FED In 2009, Insists on Confusing Consumers With Yet Another

Display Technology", Gizmodo, 9 April 2007 Sumner Lemon, "Sony spinoff plans high-end FED monitors for 2009", IDG News

Service, 4 October 2007 Christopher MacManus, "Sony Delays Acquisition of FED Factory", Sony Insider,

5 November 2008 "Sony's Field Emission Technologies closing its doors". Engadget. Retrieved

2009-03-27. http://www.digitimes.com/news/a20101117PD210.html
