Head up Display
ABSTRACT
A head-up display system projects an image directly onto the
human retina with low-energy lasers or LCDs. Head-up displays can
give the user ' the illusion of viewing a typical screen-sized display
hovering in the air several feet away. In principle the technology can
provide full-color, highresolution dynamic displays, but in practice the
components necessary to achieve the full potential of the technology
are either highly expensive. ; Although the technology was invented by
the University of Washington in the Human Interface Technology Lab
(HIT) in 1991, development did not begin until 1993; the technology
still needs much refinement and has only been commercialized in
specialized sectors of the display market such as automobile repair and
some parts of the military.
The head-up display is highly efficient with respect to
power consumption, requiring far less power than the
postage-stamp LCD screens used commonly in today's
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Head up Display
mobile devices. A head-up display uses about a microwatt
of power. Since head-up display displays project images
directly onto the retina, they provide a sharp, clear image
regardless of external lighting conditions. Head-up displays
require a fraction of the hardware of conventional display
devices, allowing for lighter and more elegant mobile
devices, in high demand for today's electronics market.
Head-up display shows strong potential to replace LCD
screens in cell phones, handheld computers, handheld
gaming systems, and eventually even larger computers such
as laptops.
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Head up Display
CONTENTS
• INTRODUCTION 4
• PRINCIPLE 7
• WORKING 13
• ADVANTAGES 19
• APPLICATIONS 20
• CONCLUSION 30
• REFERENCE 32
INTRODUCTION
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Head up Display
Our window into the digital universe has long been a glowing
screen perched on a desk. It's called a computer monitor, and as we
stare at it, light is focused into a dime-sized image on the retina in the
back of our eyeball. The retina converts the light into signals that
percolate into your brain via the optic nerve.
Here's a better way: paint the images themselves directly onto
your retina, and eliminate that bulky, power-hungry monitor
altogether. To paint the images, use tiny semiconductor lasers or
special light-emitting diodes, one each for the three primary colors
(red, yellow, and blue), and scan their light onto the retina, mixing the
colors to produce the entire palette of human vision. Short of tapping
into the optic nerve, there is no more efficient way to get an image into
your brain.
The advantages, at least for some viewing situations, are
overwhelming. If the light was scanned onto only one of your retinas,
images could be overlaid on your view of real objects, giving you an
animated, X-ray-like glimpse of the simulated innards of something,
such as a car's engine or a human body. Alternatively, if slightly
different images were scanned into each eye, grippingly vivid three-
dimensional scenes could be rendered, with pure, jewel-like spectral
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Head up Display
colors. Gainers would experience a heightened sense of reality that
LCD goggles could never provide, because the laser or LED-based
system could dynamically refocus to simulate near and distant objects
with utter realism.
Best of all, the system would waste essentially no photons so it
would be fantastically very well suited to the low-power requirements
of mobile devices. In round numbers, lasers or LED's would use
hundreds of times less power than a small LCD screen typically sub
notebook or I handheld personal digital assistant. Imagine a cell phone
or a PDA with a small, camera-like viewfinder that, by stimulating
your retina when peered into, would show you an image rich in colour
and detail. the image would appear to your brain as large as brightly lit
display screen 65cm away , which could be reconfigured quickly
from , say , a traditional boxy 4:3 format to the widescreen 16:9 format
.
The forerunners of such systems, known as scanned-beam
displays, are just now hitting the market. They're moving into the
automotive-service industry to help service technicians keep track of
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Head up Display
the huge and ever changing reams of engine data precisely where and
when they need them-in the service bay, as they are working on a car.
This first-generation system, from Microvision of Bothell, Wash., was
introduced to auto dealers earlier this year at the National Automobile
Dealer Association conference in Las Vegas. Test of the Nomad at the
American Honda Motor Co. training center. An in Torrance, Calif.,
showed that skilled service technicians performed complex repair
procedures in 39 percent less time, on average. Surgeons and U.S.
soldiers are also testing the system. Offshoots of that technology will
pop up in bar-code readers, endoscopes, and digital cameras, where
scanned-beam displays provide better image quality at lower power
and cost than liquid crystal on silicon and organic LEDs.
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Head up Display
PRINCIPLE
Head-up display have now become so compact and lightweight
that an emerging use is for displaying information to workers on site
locations such as power stations, airports and events. A new breed
monocular headup displays (HUD) cater for this application.
These displays are discreet and easy to use and are being used in
the field by engineers, security and police forces.
Head-up display utilizes a low powered laser device to literally
project a laser image onto the viewer's retina.
We are aware of the harmful effects of the laser and may be
wondering about the safety of aiming laser light directly into the eye.
To ensure that its device is safe, Microvision applied rigorous safety
standards from the American National Standards Institute,
Washington, D.C., and the International Electrotechnical Commission,
Geneva, derived from years of studying the effects of light on the eye.
Laser light can be harmful because its beam is intense, capable of
concentrating its power in a tiny area of incidence. This could be a
problem if a fixed beam-as opposed to a scanned beam-were allowed
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to dwell on just one spot. We ensure that the retina is never overw
overwhelmed by limiting the power of the laser light entering the eye
to about a thousandth of a watt and using a high-reliability interlock
circuit that turns on the laser only when the beam is scanning.
Furthermore, because this very low-power light is continuously
scanned onto the retina, its energy is dispersed over an area hundreds
of thousands , of times larger than a single spot of an incident beam.
Head-Up Display, also known as a Heads-Up Display or simply
HUD, is any type of display that presents data without blocking the user's
view. In civil aviation the HUD is known as a Head-Up Guidance
System (HGS).
There are two types of HUD:
• Fixed- In which the user looks through a display element attached
to the airframe or vehicle chassis. Commercial aircraft and motor
vehicle HUDs are of this type. The system determines the image to
be presented depending on the orientation of the vehicle. The size
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Head up Display
and weight of the display system can be much greater than in the
other type which is:
• Helmet-mounted, or head-mounted-In which the display element
moves with the user's head. This requires a system to precisely
monitor the user's direction of gaze and determine the appropriate
image to be presented. The user must wear a helmet or other
headgear which is securely fixed to the user's head so that the
display element does not move with respect to the user's eye. Such
systems are often monocular. One use of this type of HUD is in the
AH-64 Apache and in the Norwegian F-16 Fighting Falcons.
HUDs have in common the following characteristics:
• The display element is largely transparent, meaning the
information is displayed in contrasting superposition over the
user's normal environment
• The information is projected with its focus at infinity. Doing this
means that a user does not need to refocus his eyes (which takes
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Head up Display
several tenths of a second) when changing his attention between
the instrument and the outside world.
The company uses microelectromechanical system (MEMS)
devices to scan the beams back and forth and, where appropriate, to
mix different colors to produce white light. Because the beam sweeps
over the retina instead of dotting it, lines need not be serrated and
images need not be grainy. Bright as the picture will seem to the
naked eye, it will consume barely a microwatt, potentially saving
hugely on battery power. And, by sending light only where it's
needed, the system can keep nosy neighbors in adjacent airline seats
from snooping on your work (or play). With a sufficiently
inconspicuous eyepiece, one might even feign attention to a speech or
lecture while, in fact, watching television.
Resolution and Colour Depth, and Brightness:
The overriding design factor for these type of Head-up display
is their compactness which means that the resolution of these models
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Head up Display
is not yet as high as some of the virtual reality Head-up display. Older
HUD's offers resolutions starting from 320x240 (qVGA) up to 640 x
480 (VGA) and includes true colour models. They are also available
in binocular configurations to give twice the display area.
Microvision's Nomad has a resolution of 800 x 600 and is red-
monochrome. Colour is not important for many applications where
content is mainly technical data and text. Microvision's displays use
red laser light. One of their strong points is that they are very bright
and can easily be viewed in strong sunlightField of view
(FOV)Average human vision covers an area of about 200 degrees
horizontally by 150 degrees vertically. FWD FOV figures are typically
given as diagonal FOV. That is the perceived angle from one corner of
the screen to the opposite corner.
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Head up Display
(a) (b)
(a) Approx. human horizontal field-of-view (b) Approx.
human vertical field-of-view
One of the most important factors for head-up information
display is that any text or technical diagrams are clearly legible. These
Head-up display are currently not designed to immerse the user with
wrap-around images but instead to provide the equivalent of a 'floating
monitor' taking up part of the user's field of view
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Head up Display
WORKING
There are just four primary components of a scanned-beam
display: electronics, light sources, scanners, and optics. Yet with a
modular approach, these simple elements can be combined to yield
many different products.
Electronics acquire and process signals from an image or data
source, such as a Web page or video camera. The processed signals
contain information for the intensity and mix of color that best
renders the intended image at each location that will be scanned, in
sequence. These values are the individual picture elements-pixels-that
make up the image. This information is stored in memory until
needed, when the data pass through a digital-to-analog converter that
controls the light source. Once the image has been rendered into
memory, there is no need to recalculate it unless something has
changed. The data can simply be replayed from memory, a feature
that can be exploited to cut costs or save power.
In the scanned beam display headset the viewer sees an image when
modulated signals from laser diodes sweep across the retina. A
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microcontroller in the visor selects the image from the view memory
and passes it to digital to analog converters. These produce signals
that Control lasers - red, green and blue-for a full color display. The
modulated light passes to a tiny scanning mirror and then to a pupil
expander that allows for eye movement by enlarging the image Next,
the images reflected in to the eye and onto the retina.
Projection methods
The most common means by which current HUDs are implemented is to
project the image onto a clear glass optical element ('combiner').
Traditionally, the source for the projected image has been a Cathode Ray
Tube (CRT), however newer image sources based on micro-display
technologies are now being introduced. Micro-display technologies that
have been demonstrated include Liquid Crystal Display (LCD), Liquid
Crystal On Silicon (LCOS), Digital Micro Mirrors (DMDs), Organic
Light-Emitting Diode (OLED) and Laser.
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Head up Display
Depending on the application and cost and size requirements,
we can use single color or multiple low-power solid-state lasers, laser
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diodes, or LEDs as the light source. In the case of a full-color
electronic viewfinder display on a camera where low cost and power
consumption are critical, I modulated red, green, and blue LEDs
produce color pixels of varied'intensities to generate a complete
palette of colors and shades.
If the light source is the paint, Microvision's proprietary
mieroeiectromechanical systems (MEMS) biaxial scanner is the brush
that applies the image to the retina. The scanner's main component is
a minor 1.5 millimeters in diameter that rapidly sweeps the light
beam horizontally to position the pixels in a row, also moving the
beam downward, to draw successive rows of pixels. This process
continues until an entire field of rows has been placed and a full
image appears to the user-quite similar to the process in a regular
cathode-ray television, in which the magnetic deflection coils direct
the electron beam to scan the phosphor-coated screen. But while a
conventional display can create jagged edges on images because the
pixels are fixed onto screen hardware, a scanned-beam display has no
hard pixels: the continuously scanning beam creates a much smoother
image.
For applications in which the scanned-beam display is to be worn on
the head or held closely to the eye, we need to deliver the light beam
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Head up Display
into what is basically a moving target: the human eye. Constantly
darting around in its socket, the eye has a range of motion that covers
some 10 to 15min. One way to hit this target is to focus the scanned
beam onto an optical element called an exit pupil expander. When
light from the expander is collected by a lens, and guided by a mirror
and a see-through
monocle to the eye, it covers the entire area over which the pupil
may roam. For applications that require better image quality using
less power, we can dispense with the exit pupil expander altogether
either by using a larger scan mirror to make a larger exit pupil or
by actively tracking the pupil to steer light into it.
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Head up Display
Display using CRT
ADVANTAGES
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Head up Display
The head-up display is highly efficient with respect to power
consumption, requiring far less power than the postage-stamp LCD
screens used commonly in today's mobile devices. A head-up display
uses about a microwatt of power. Since head-up display displays
project images directly onto the retina, they provide a sharp, clear
image regardless of external lighting conditions. Head-up displays
require a fraction of the hardware of conventional display devices,
allowing for lighter and more elegant mobile devices, in high demand
for today's electronics market. Head-up display shows strong
potential to replace LCD screens in cell phones, handheld computers,
handheld gaming systems, and eventually even larger computers such
as laptops
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Head up Display
APPLICATIONS
The following applications are where the majority of these
displays are used:
Law Enforcement, Medical, Military, Service Technicians,
Automotive Technicians, Non-destructive Testing, Security, Test and
Measurement, Video production, Mobile Computing, Consumer video.
Head-Up displays were pioneered for fighter jets and later for low-flying
military helicopter pilots, for whom information overload was a
significant issue, and for whom changing their view to look at the
aircraft's instruments could prove to be a fatal distraction.
HGSs have been in use in commercial aviation since the 1970s, and are
now in regular use, notably with Alaska Airlines.
Heads up displays have also been incorporated into automobiles, usually
as a secondary display for the most important information from the
gauges. General Motors was the first to put the Heads up Display into
cars in 1988. These early HUD units were made by Hughes Aircraft
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Head up Display
Corporation, a GM subsidary. One of the first vehicles to receive a HUD
was the May 1988 Indianapolis 500's 1988 Cutlass Supreme Pacecar,
as well as 50 custom convertible pacecar replicas commissioned by GM.
Since 1988 General Motors offered the Heads Up
Displays as an option on the 1989-1994 Oldsmobile Cutlass Supreme,
1989 to present Pontiac Grand Prix, and 1993 to present Pontiac
Bonneville, and more recently the Buick LeSabre, Park Avenue and
Rendezvous.
During the 90's, Heads Up Displays were an option offered in Nissan
models including the Silvia family of cars.
In 1999, Automotive HUD technology made a big quality leap with the
Chevrolet Corvette. The new Corvette, which uses a HUD to display
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vehicle speed, engine RPM, Navigation and more, has proven the HUD
to be one of its most popular options.
In 2000 Cadillac Premiered an optional night vision driving system as a
secondary aid for drivers. It utilizes a monitor set in the dash that
displays a generated night vision image of the road, using an infrared
camera
As of 2006 BMW now features the head-up display as an option on their
5 and 7 series vehicles, with more HUDs being anticipated from other
European and Japanese OEMs.
As the doctors operate the patient, the surgeons are viewing vital
patient data, including blood pressure and heart rate. And in such
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procedures as the placement of a catheter stent, overlaid images
prepared from previously obtained magnetic resonance imaging or
computed tomography scans assist in surgical navigation.
Several military units, including the U.S. Army's Stryker
Brigade, are using adaptations of the system. The commander of a
Stryker, an eightwheel light-armored vehicle, can view its onboard
battlefield computer with a helmet-mounted daylight-readable display.
This enhances the commander's ability to observe the surroundings,
choose the
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Optimum path, command the vehicle, and use tactical
information advantageously. Other military applications include a
series of prototype helmet-mounted displays developed with the U.S.
Army and Boeing Co. of Chicago. Currently in the initial stages of
flight-testing, the system could be a relatively inexpensive way to
provide utility- and attack-helicopter pilots with a digital display of the
battle space.
Displays from both MicroOptical and 1Vlicrovision are suitable
for outdoor usage and both are capable of connecting to handheld PCs
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Head up Display
and PDAs. Microvision's Expert Technician System includes a
wearable running Windows CE.NET and is tough enough to be used in
industrial environments. MicroOptical's displays are often used with
wearable computing system. They are also available with video inputs
allowing use with DVD players or Camcorders.
HUDs have been proposed or experimentally developed for a number of
other applications, including:
• overlaying tactical information onto the vision of an infantryman
(such as the output of a laser rangefinder or the relative location of
the soldier's squadmates)
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Head up Display
Providing basic information for car drivers, by projecting an image
(again, at infinity) onto the inner surface of the car's windscreen. This
has been released as a product by a few manufacturers[1] (usually
showing a speedometer) but is presently illegal in several jurisdictions
(where laws prohibiting driver-viewable TV sets currently include
HUDs). HUDs are likely to become more common in future vehicles.
• In the James Bond story Licence Renewed, Bond's car, a Saab 900
turbo, was fitted with a HUD.
• providing surgeons with an enhanced view, showing the results of
x-rays or scans overlayed over their normal view of the patient,
and thus allowing them to "see" structures normally invisible.
might be displayed at once, with the rest being rotated into view using the
[ and ] keys. There is also a lot of variance with regards to the display of
other information. Some games permanently display all the weapons a
character is currently carrying, others rely on a pull up weapon selector.
Inventory or storage space may also be permanently overlaid over the
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Head up Display
screen, or accessed via a menu. Alternatively, only a limited number of
items stored in the inventory
The HUD in Metroid Prime is explained as being displayed by the character's helmet.In order to maintain the suspension of disbelief,
SAN JOSE, Calif. — A new head-mounted display (HMD) venture,
MicroOptical Corp., will demonstrate an unobtrusive display next
month that can be clipped onto or integrated into conventional
eyeglasses. A step beyond the latest lightweight, ergonomic
headgear, MicroOptical calls its Eyeglass Display the first truly
practical HMD.
The HMD arena is due for a dose of practicality, sources said,
having failed to move much beyond the heavy, expensive
headgear for technicians and maintenance workers who absolutely
require a hands-free screen. The crop of miniature-LCD
technologies brought to market within the past year is a breath of
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Head up Display
fresh air for HMDs, however. MicroOptical's design is based on
such an LCD, but the company applies the display to the
wearable-monitor problem in a novel way.
"The conceptual demand for HMDs is very high but nobody's
gotten the ergonomics right," said Tom Holzel, vice president of
sales and marketing for MicroOptical (Westwood, Mass.) , which
will demonstrate the Eyeglass Display at the at the Society for
Information Display conference in San Jose, Calif.
Holzel called the integrated version "a featherweight personal
display with an appearance nearly indistinguishable from
conventional glasses. We can build this monitor into prescription
eyeglasses, safety glasses, military goggles, whatever. We just
need a couple of millimeters of glass to shoot light into from the
side."
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CONCLUSION
As with most hi-tech electronics, head-up displays are set to
become smaller and lighter. MicroOptical is working towards a model
that will look no different to a normal pair of glasses. In the near
future, head-up displays will be available with wi-fi and Bluetooth
connectivity, allowing user's to surf the web and check their email on
the move.
There will also be devices that will create full colour images
that look bigger than a cinema screen, from a tiny head-mounted or
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handheld device. This will open up applications such as augmented
vision and augmented reality.
Car dashboard information could be displayed by such a
display, allowing real-time information on the car, traffic and
directions, to be superimposed anywhere in the driver's field of view.
Mapping will take on a new leash of life with augmented reality
and GPS technology. Users will be able to see a map of their current
location displayed right on top of the real thing. This will aid
navigation in cities and the countryside, allowing street names to
appear on every road and virtual sign-posts to lead you to your
destination. Local information such as the nearest police or tube
station could be overlayed onto your view along with directions to the
nearest cash point or taxi rank.
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REFERENCE
www.wikipedia.org
www.microoptical.com
www.iec.org
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HEAD UP DISPLAY
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BHAVIK TP S7 EC NO.9
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ACKNOWLEDGMENT
I would like to place on record my deep sense of gratitude to
Mr.PURUSHOTHAMAN Head of Department of Electronics &
communication, V ima l Jyo th i Eng ine e r ing Co l l e ge for his valuable
help and guidance in carrying out the seminar.
I also thank all the staff of The Department Electronics &
Communication for their assistance and encouragement through out the
course of the seminar.
Last, but not the least I would like to thank my parents and
friends who encouraged me and gave me the motivation to complete the
seminar.
Above all I would like to thank God for His abundant grace upon my seminar.
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