Roll No: 40
M.C.A I sem
Newer display technologies continue to evolve, in
synchronism with modern-day convergence devices and systems.
However, the general awareness and knowledge about display systems
are on a lower level, compared to the hype of related developments in the
convergence arena. A concerted port is needed by the diverse fields to
develop effective, efficient, and economical display systems.
What are display systems?
Display systems are the focal point of any human-machine
interface. Applications range from digital watches, finger tops, palmtops,
laptops, mobile phones, digital cameras, PC monitors, and TV’s to public
scale hoardings and air-base displays. Related innovations have enabled
display systems to synchronize the corresponding advances in micro
electronics, IT, and telecommunication fields. The role of electronic
displays is becoming increasingly crucial consumer electronics, office
automation, information processing, entertainment, intelligent
offices/homes, interactive services, teleshopping/conferences, trade-
Display techniques form an essential component of any
industry, be it any manufacturing, process control, education,
advertising/marketing, automobile, chemical electronic, nuclear,
publicity, public information, or any other area can conceptualize. Trade
shows, executions, seminars, etc effectively use electronic displays to
highlight their product innovations. Thousands of visitors stroll through
the exhibit halls, of which most flock around those booths that offer
Display form a crucial link in the functioning of convergence
systems. Product manufacturers can easily capitalize on these systems.
All it takes is a little more bragging on their part.
Technique behind Display Systems:
Electronic devices convert electronic signal information to
specific locations on display screens. Each location must adjust to the
requisite brightness and colour for that portion of the image. Display
systems use a wide range of modalities categorized mainly into direct
view and projection systems. Direct view systems enable the users to
view the display screen directly. Projection systems first create the image
on an internal screen, subsequently using optical devices to magnify and
project images onto a larger external screen.
These displays can also be classified as light-emitting and
non-light-emitting devices. Light-emitting devices include cathode-ray
tubes (CRT’s), electroluminescent (EL), plasma display panels (PDP’s),
vacuum fluorescent displays (VFD’s), field-emission displays (FED’s),
and light-emitting diodes (LED’s). Non-light-emitting displays include
liquid crystal displays (LCD’s) and electro chromic displays (ECD’s).
A sampled interaction with the display industry reveals
interesting aspects about this seemingly innocuous and taken-for-granted
S.K.Garg, president, Super-Vu International, a leading
domestic player and exporter, emphasizes that the display technology is
changing very fast. Obsolescence is very fast. For instance multimedia
data projectors marketed by Indian companies get outdated in only 3 to 6
months. An SVGA model is outdated in six months, since it can be
upgraded using technology available, Plasma displays, developed by
America and Japan, are expensive. These support only VGA video inputs,
and cost Rs. 5,50,000 per unit. Super Vu has developed a 114cm Plasma
Vision display system that costs only Rs 75,000. This simple system
integrates flexibility of up gradation and transportation.
India is a vast untapped market for display systems. Mr.Garg
is of the opinion that, both in terms of quality and cost, we can complete
with imported versions. We have the capability to design and
manufacture large video walls at half the cost of imported models. The
company has a development facility to design and fabricate sophisticated
optical systems for any application. Based on the feedback and
techoeconomic requirement, display systems have been developed for
‘Plasma Vision’ (compact, portable rear-projection monitor),
‘Display Vision’ (standalone large-screen, rear-projection monitor),
‘Movision’ (portable, powerful, high-resolution display), ‘Media Vision’
(large-screen interactive multimedia presentation tool), and ‘Video wall /
Video cube’ (large screen display) are some display products that have
good demand in the domestic and global markets. Applications include
showrooms, corporate presentations, simulators, command and control
centers, large drawing-rooms, halls, exhibitions, heavy-traffic public
places, and training sessions.
There are few Indian companies with the requisite
infrastructure to design and develop, or even assemble, a complete range
of projection systems. R.D. Vaghela, CEO, Infra Control Systems,
reveals that the trend worldwide is to use smart display systems that can
be activated by pager networks at specified time for advertisement
booking time-slots. In European countries displays depict news flash of
important events, weather information, etc.
These are used in factories for production data analysis and
display of MIS (Managerial Information Systems) information pertaining
to number of parts to be produced per day, actual production, and rejected
parts. In the assembly line, time taken by technicians in each zone is
displayed. If it is longer than the stipulated time, reason for the efficiency
or any mechanical problem of the assembly is found and rectified.
Common usage areas include stock and commodity exchange update,
manufacturing / warehouse data management and employee and safety
communications in large facilities.
Corporates use displays with RS48 interface, enabling 255
displays to be attached to one computer. Centralized computers transfer
data to various locations, according to ID number given to each display.
Same message can transmitted to all displays in emergent situations.
Displays can accept pager situation data. Display messages can be
entered by wireless remote control keyboard, computers using dedicated
software, and paging date receivers.
Personal priority display (PPD) is popular abroad.
Specifically designed for high-priority desktop messages, it
communicates critical, time sensitive information to workstations. It is
statically placed inside helpdesks in customer service workstations / cells,
office and lobbies, so that critical data is immediately and easily
In India, displays are mainly use passing general and online
information. Power utility companies display online production data and
related crucial parameters. Mr.Vaghela explains that Indian industry is
installing silent message displays and studying their impact on viewers.
Displays are ideal communication tools.
Jayant Shah, partner, Automobile Industries, leading
manufacturer electronic displays, feels that there is need to increase
public awareness usage of this technology. Since 1999 electronic
displays have been a vital display communication media over the world.
Automotive Industries has developed innovative LED displays, signs and
Indian electronic display industry is growing. Industries use
displays for production and safety signs. Displays on roadways
communicate civic messages and advertisements. Sunil Shah, partner,
Jaydeep Industrial Corp., reveals that companies prefer to install LED
displays that are more economical than LCD and plasma, Mr.Shah
laments that the sales of display products are affected by high sales tax.
As more corporates and government organizations are using display
systems, there is a scope for growth. The display industry should take
care to develop quality products, to sustain this growth.
Touch systems as GUI(graphical-user interface) devices for
computers continue to grow in popularity. For many applications such as
ATMs POS (Point-of-sales) systems, industrial controls, and handheld
computers, touch screens are an essential user interface, not just a
The touch system comprises touch sensor (to receive the
touch input), electronic controller (to read and translate the sensor input
into a conventional bus protocol; for example, serial USB), software
driver (to convert the bus information to cursor action), and system
utilities, Vacuum-deposited transparent conductors serve as the primary
sensing element in both capacitive and resistive touch sensors- the two
most common touch sensors.
Touch systems using resistive sensors account for 56 per
cent of the touch market, with 43 per cent going to high volume
consumer applications. These applications predominantly utilize ‘pen
input’; for example, PDAs. Premium applications, such as retail POS, or
those where glove input is most frequent, such as medical and clean-room
displays, make up the balance of the resistive market.
Capacitive touch systems account for 25 per cent of the
global touch market sales. Known for their durability, reliability, and fast
response, those sensors service public-access touch-screen applications,
such as information kiosks, ATMs, and casino gaming. These systems
activate with either human finger touch or an electrically active tethered
Touch systems represent a rapidly growing subset of the
display market. Palas Software and Micro touch, USA, have pioneered
usage of state-of-the-art ‘Micro touch’ screens in India. Micro touch,
Boston, is a world leader in touch technology. Its patented ‘ClearTek’
touch-screen is sensitive. It registers the lightest touch, with high
resolution, and requires the shortest touch contact. It is the only
technology unaffected by dust in the world, which makes it ideal for
Other touch-screen innovations include intelligent pen-and-
touch input with ‘TouchPen’, ‘Tek resistive’, and ‘Thru Glass’ systems.
Use of touch-screen installations is increasing in India. Applications
include games / entertainment, industrial / medical instrumentation,
financial trading, ATMs, POS terminals, retailing kiosks, multimedia
Micro Touch has a major share of the global touch-screen
market. Rajiv Srivastava, director, Palas Software and Micro touch India,
predicts touch screens will be the future input interface for computerized
systems. The worlds over these systems are being utilized as user friendly
interfaces, obviating the need for computer and keyboard skills. In the
Indian context, people with low literacy levels can benefit from the
Public information systems, such as railways, use these
systems for booking offices. Travelers can confirm reservation by
touching the ‘PNR number’ location on the screen. Even illiterates can
use and benefit from the system. Touch screen can be sued for accessing
information in any language. Bill Gates, chairman, Microsoft, predicts
that it will emerge as a vital computer interface.
‘ClearTek’ touch-screen uses analogue capacitive technology- the
only touch technology based on sensing electrical signals. It has a
resolution of 1024 x 1024 touch points. The controller averages the entire
area of finger contact to a single point, giving users pixel by pixel control.
ClearTek also provides the fastest response of any touch-
screen, with a minimum touch contact requirement of 3 cms. This
performance offers virtually instant response and makes it ideal for
various applications, including gaming and kiosks, where environmental
robustness is a necessity. Most public access kiosks in India use
Thru Glass is a revolutionary concept in computer input
devices, based on a patented projected capacitive touch technology. It can
detect a touch through 2.5cm thickness of glass, plastic, or non-
conductive protective materials. This versatile technology can be used
with multimedia system installed in environmentally controlled kiosks to
create vandal-proof, unattended, outdoor application.
For the rigid demands of a factory floor, Thru Glass is the
perfect solutions capable of being activated with any conductive input
device including glove hands and metal tools. Impervious to rain, snow,
chemical and sunlight, brings the power of touch into new environments.
‘TouchPen’ is a proprietary capacitive digitizer using Micro
Touch’s analogue capacitive touch technology. It is only technology that
can distinguish between touch and pen input. It works by generating a
uniform low-voltage field over the sensor and determines the touch
location in the same way as the analogue capacitive screen does. A pen
location is determined when the pen injects current onto the conductive
surface. The touch contact requirement 3 cms. The response speed is 8 to
15 cms and 200 points per second in pen model.
With a resolution of 2048 x 2048 touch points, the digitizer
is fast and precise enough for signature capture, image manipulation, and
annotation. It is offered as a standard option with an analogue capacitive
kits and monitors.
Shonkh Technologies has developed information kiosks with
LCD/CRT touch screens, adding power to interactivity. Basically, a kiosk
is an information centre. It can be a standalone system connected to a
server, or to the Internet, enabling users to access the information bank.
Kiosks have bridged the gap between the computer-literate and the non
A German company has developed laser imaging
technology, endowed with best colour properties. Laser display
projections obviate the need to focus the protector to adjust for the
distance between the projector and the screen. These provide clear, non-
reversed images on the screens of any size. Laser beams travel over the
screen incredibly impact, creating on it a succession of images made up
of pixels and lines. The pixel and frame rates are the same as of the
common video standards.
The laser imaging method can use signals from all standard
norms, included analogue, digital, and HDTV, readies of whether these
are received an aerial or video recorder.
The multisync and multimedia capabilities of laser
projections make them for events, shows, exhibitions, and conference
rooms. A small projection head attached to the ceiling in a domestic
living room can beam life-like video images measuring 1.5 m (diagonal)
at an angle from one of the walls of the room.
ORGANIC EL DISPLAYS:
Most flat panels in the market are LCDs. But LCDs are essentially
non light-emitting devices. This imposes technical limitations on the
quality of ability they offer. So, the display industry is forced to continue
R&D efforts for displays that emit their own light. Such displays include
PDPs, FEDs, and EL displays.
Organic electroluminescence (EL) displays, in addition to
emitting their own light, provide wide viewing angles, feature a strong
contrast, and deliver a quick response speed. These possess strong
characteristics in areas where LCDs are weak. These use fluorescent
organic compounds as luminescent materials.
Researchers at Tohou Pioneer Corp., Japan, experimenting
with compounds having low molecular weights, developed element
technologies necessary to create organic EL displays. They brought out
an organic EL display for car radios. To form devices made of low
molecular weight compounds, vacuum evaporation techniques are used to
deposit organic compounds with different carrier transport factors
between electrodes possessing different work functions. Glass or plastic
film substrates use indium-tin oxide (ITO) as the positive electrode, with
a high work function of 5.0 eV, performing as a hole injection electrode.
The EL devices basically consist of cathode (Li-Al or Mg-Ag), electron
transport layer (Alg3), emission layer with dopant (Alg3, quinacridone, or
coumarine), hole transport layer (amine-based compound), anode, and
The advanced organic EL dot-matrix device developed by
the company has green monochrome display section with 265 x 64 dots
and single-matrix drive structure. The displays have panel and drive
circuit sections. The resulting display, with superior brightness, contrast,
and visibility, can be viewed at any angle. To take full advantage of the
self-emitting characteristics of EL devices, the external light is blocked,
preventing it from entering the panel and reducing contrast.
Researchers continue to seek ways of making organic LEDs
more efficient and longer lasting. They have succeeded on both counts by
using new materials and by combining materials is new ways, creating
displays lasting 10,000 hours and delivering a luminous efficiency of 12
lumens per watt.
Organic EL displays find usage in the display section of
Pioneer’s vehicle use FM teletex receivers. Demands are on the increase
from manufacturers of car stereo systems. These displays will also be
supplied for various other devices, including PDAs.
LEPs are flat, wall-hanging displays that are produced using
plastic layers. These were invented by Richard Friend, University of
Cambridge, in 1989. Cambridge Display Technology (CDT)
demonstrated the first LEP-based monochrome flat TV screen in 1998.
LEPs operate on supply voltages of 3V and less, with wide viewing
angles. This light-emitting device is a layer structure deposited on a
transparent substrate. The substrate is coated with a transparent
conducting layer, ITO, which is used as a hole injector. ITO has a rough
surface relative to LEP. It is coated with a conducting polymer. The
second electrode (a film of calcium over laid with another film of
aluminium) is deposited on the LEP layer, completing the sandwich
structure of the device. Electrons and holes, injected into the LEP from
cathode and anode, recombine to form excitons that radiate photons
during decay. The band-gap and colour emission can be varied through
the visible light spectrum (from blue through the red).
CDT has linked up with Seiko-Epson, Philips, Hoest, Seiko,
and DuPont, to undertake development work on various aspects of LEP-
based display. Philips is introducing multi colour displays for mobile
phones, while Seiko is working on a large-area flat screen with full-
colour video display.
VIDEO DIGITAL INTERFACE
An industry working group, led by Intel and backed by
Compaq, Dell, Fujitsu, Hewlett-Packard, IBM, NEC, Microsoft and
Silicon Image is developing a digital interface technique. This technique
will eventually link consumer electronics, PCs, or any host system to
Unlike CRTS, flat-panel displays are inherently digital. Every pixel
is individually addressed. The display requires matrix-addressing
circuitry. Unfortunately, most flat-panel monitors in the market today are
connected to the PC via the VGA video monitor port. The VGA analogue
outlet socket at the back of every PC delivers analogue colour RGB
signals, which in turn, drive a CRT. For flat-panel displays, the signals
are, however, reconverted into digital format through A/D conversion
process. This double conversion process degrades image quality and ads
cost. A better solution is to keep the video signal in digital format
The superior image quality of active matrix LCDs in the
latest notebook computers is due to the use of a digital link between the
PC motherboard and the display. But notebooks are closed integrated
systems where compatibility between manufacturer’s motherboard and
display is not an issue. Before the same image quality is achieved in the
desktop PC, the industry needs a digital video interface technique that
permits operation in an open system environment. By combining the
digital video interface standard with the latest generation of digital
displays, system designers can enjoy the benefits of super image quality,
lower system cost, increased ease of use, and the ability to transmit
images over long distances.
LCD is a passive device that manipulates existing light to
produce an image, whereas active displays (CRT, plasma, and LED) emit
light. Consequently, it consumes low power and, therefore, is the
preferred choice in portable and other battery-powered applications.
Touch-screen LCD (TSLCD) modules incorporate drive
electronics and touch panel logic to display data, scan touch panel, sense
operator inputs, and output digital data to a control program. The touch-
panel portion of LCD can be programmed to display a variety of data,
such as alphanumeric, ‘QWERTY’ keyboard, icons, and other graphics.
Touch panels use capacitive or resistive sensor technology. Increased
display luminance, increased viewing angle by using better aperture ratio,
new substrates, better backlights, etc are the current trends.
PCs equipped with thin-film transistor (TFT) LCDs were the
first to be noticed. Subsequently, TFT colour LCDs helped stimulate the
widespread use of notebook computers incorporating such displays.
Advances in TFT LCD manufacturing techniques further contributed to
the spectacular spread of notebook computers. These modules continue to
develop for use as monitors for desktop computers and workstations.
These are appearing as terminal displays in banking institutions, stores,
desktop publication, and computer-aided applications.
The demand for LCD panels for use in cell phones is
expected to raise sharply after the launch of 3G mobile services,
providing data and full-video transmissions. Japanese electronic giants
are beginning to produce LCD panels for use in cellular phones, to cash
in on their rapid demand fueled by 3G cellular phone services. Toshiba,
Sharp, Seiko Epson, NEC, Casio Computer, etc are some of these.
Hitachi started producing colour power-saving STN (super
twisted nematic) LCD panels for cells phones and is now developing TFT
LCD panels that can display full-motion video. The global market for
TFT LCDs will continue to expand, boosted by Philips Electronics NV
and LG Electronics. The two companies formed a successful joint venture
last year, to pool their CRT activities. The venture will combine all CRT
activities and key components, as well as the glass activities and plasma
technologies of both the firms.
Invented in 1966, VFDs have been in the market for 34
years. These versatile displays have gone through continuous
improvements in their technology, and are used in many devices and
systems. Application area includes automation, telecom, medical, home
appliances, vending machines, point of sale, public information systems,
VFDs are amenable for small-size production and reused
widely as chip on-glass displays, especially for automotive applications.
Super VFD tubes consume low power and obviate the need for
backlighting. Tube structures are being improved to offer better viewing
angles. Multicolour displays use modular techniques and apply strips of
The three flat-panel displays active matrix LCDs
(AMLCDs), plasma-addressed liquid crystal (PALC) display and PDPs-
can be classified into light modulators or light emitters. AMLCD and
PALC displays are examples of the former, in which the functions of
light generation and light modulation are separated. Light modulation is
accomplished via a voltage-controlled change in the polarization of light
passing through a liquid crystal. A separate backlight provides the
illumination. PDPs, light generation and modulation functions are
combined by mechanisms whereby variable amounts of UV light are
produced, which stimulate the phosphor to emit visible light.
The AMLCD is a mature technology, with a large
manufacturing base and established production infrastructure.
Polyster is the likely choice for future flat-panel displays.
Researchers have developed thin-film transistor displays out of
polyethylene terephthalate thin, flexible and rugged plastic can be rolled
up, folded, or bent it practically any shape desired.
The concept holds promise for a future generation of ultra-
light, flexible, cost-effective displays. Applications include notebooks,
desktops, video-games, machines, and non-conventional displays. Roll-up
displays, displays set into clothing, paper-thin electronic books, and
newspapers are some of novel innovations.
Unfortunately, 3D displays have not measured up to
expectations. In some cases, viewers must wear special glasses to have
their viewing system restricted. However, improvements are in the office,
with medical and business devices consisting glassless technologies.
Splitter system is used in amusement applications, and will
find more applications as LCD price falls and picture quality improves.
Double-image splitter system is used in business applications, binoculars,
and stereoscopic emission tests. Medical field is considering the use of 38
cm display as monitors for brain surgeries and endoscopic operations.
This display uses head-tracking technology that detects the viewer’s head
and displays optical image accordingly.
‘Stereoscopic Vision’ technology for presenting 3D images
incorporates an inversion technique called modified difference. Another
system computed-image depth, effectively converts still 2D images to
3D. This system separates each subject using colour components of the
screen, and then estimates the depth of each section of images, depending
on the contrast, sharpness of each subject, and structure of the scene.
The imaging technology department at Sharp Laboratories of
Europe has developed ‘twin-LCD’ display concept. It is based on two
TFT LCDs. The images of these LCDs are superimposed by a half-
mirrored beam computer. The optical arrangement creates laterally
displaced images at the nominal observer position. Each LCD panel
displays one of the stereo pair images, enabling the observer to view the
images without wearing special glasses. Twin-LCD concept, using TFT
LCDs with a controllable illumination system, has been used to show
high reality auto-stereoscopic 3D images with observer tracking over a
wide angle and image look-around.
Optical fibre, widely known as a telecommunications
transmission medium, can be used for large displays in public places.
Such display systems consume relatively little power and deliver high
contrast, non-glare visuals in lighted settings.
As multimedia techniques progress, the market requirement
of information displayed at public locations tends to shift from
communication of data using characters to that using images. To
communicate information, the image should be large with full colours.
The multi screen method is widely used to produce a large display. A
number of display units (LCDs, CRTs, or projectors) having a certain size
are assembled to form a large-display screen. However, the drawback of
these display systems is that seams are present between the display units.
Advantages of optical fibre display systems include large
seamless screen, high design flexibility, and easy installation and
movement. These are best suited for public facilities, conference halls,
ongoing games at stadia/gymnasiums, advertisements, airports, and
Invented in 1987 by Texas Instruments, USA, digital micro
mirror display (DMD) is a reflective optical conversion device that
features bright projected image, with high contrast, narrow beam between
pixels, high resolution, and excellent colour reproduction. It uses digital
light processing (DLP) technology.
DMD is fabricated on CMOS SRAM, using micro machine
technology based on conventional 0.8 um wafer processing. This display
integrates electrical, mechanical, and optical functions on a single chip.
Thousands of 16 um2 Al mirrors are formed on a chip, at a chip, at a pitch
of 17 um. The mirrors reflect light in one of two directions, +10 0 or -100
relative to the substrate surface, depending on memory outputs. DMD is
combined with a light source and projection system. When it is applied in
a DLP optical system, light enters the DMD at 200. In ‘on’ state, the
mirror projects the light to projection lens and the pixel projected onto the
screen appears bright. In ‘off’ state, the mirror reflects lights at 400,
missing the projection lens. The pixel then displayed is black. The system
employs binary pulse-width modulation (PWM) technology. The DMD
switches the micro-mirrors ‘on’ and ‘off’ at switching speeds of 10 us to
generate bursts of optical digital pulses that appear to the viewer as a
level of brightness between fully bright and totally dark.
DMP technology can be used in business,
consumer, or commercial applications. Business applications include
front projectors for conference room and workgroup presentations.
Consumer applications include rear-and front-projection TVs.
The display field is vast. Newer display technologies
continue to evolve, in synchronism with modern-day convergence
devices and systems however, the general awareness and knowledge
about display systems are on a lower level, compared to the hype of
related developments in the convergence arena. In order to
capitalise on displays that match modern devices, a concerted effort is
needed by the diverse fields to develop effective, efficient, and
economical display systems.
ELECTRONICS FOR YOU
Living Digital March -2004