Virtual Retinal
Display (VRD) or Scan Beam Display is a new display device, in which a coherent
light source is used to scan an image directly on the retina of the viewer’s
eye. Using the VRD technology it is possible to build a high resolution, wide
field-of-view, full color personal display device that is light weight and will
operate in a high brightness environment. Current work is aimed at developing
the technologies that will make the VRD a commercially viable product from both
a performance and cost standpoint. Prototypes produced to date include a full
color, VGA resolution device based on a unique mechanical resonant scanner as
the horizontal scanning element. This paper will briefly explain the VRD
concept and discuss potential applications of the technology. It will also
describe the current research and development efforts which are aimed at
creating a high performance yet low cost display system.
Information displays
are the primary medium through which text and images generated by computer and
other electronic systems are delivered to end-users. While early computer
systems were designed and used for tasks that involved little interactions
between the user and the computer, today's graphical and multimedia information
and computing environments require information displays that have higher
performance, smaller size and lower cost.
The market for display technologies also
has been stimulated by the increasing popularity of hand-held computers,
personal digital assistants and cellular phones; interest in simulated
environments and augmented reality systems; and the recognition that an
improved means of connecting people and machines can increase productivity and
enhance the enjoyment of electronic entertainment and learning experiences.
For decades, the cathode ray tube has
been the dominant display device. The cathode ray tube creates an image by
scanning a beam of electrons across a phosphor-coated screen, causing the
phosphors to emit visible light. The beam is generated by an electron gun and
is passed through a deflection system that scans the beam rapidly left to right
and top to bottom, a process called Rastering. A magnetic lens focuses the beam
to create a small moving dot on the phosphor screen. It is these rapidly moving
spots of light ("pixels") that raster or "paint" the image
on the surface of the viewing screen. Flat panel displays are enjoying
widespread use in portable computers, calculators and other personal
electronics devices. Flat panel displays can consist of hundreds of thousands
of pixels, each of which is formed by one or more transistors acting on a
crystalline material.
In recent years, as the computer and
electronics industries have made substantial advances in miniaturization,
manufacturers have sought lighter weight, lower power and more cost-effective
displays to enable the development of smaller portable computers and other
electronic devices. Flat panel technologies have made meaningful advances in
these areas. Both cathode ray tubes and flat panel display technologies,
however, pose difficult engineering and fabrication problems for more highly
miniaturized, high-resolution displays because of inherent constraints in size,
weight, cost and power consumption. In addition, both cathode ray tubes and
flat panel display are difficult to see outdoors or in other setting where the
ambient light is brighter than the light emitted from the screen. Display
mobility is also limited by size, brightness and power consumption.
As display technologies attempt to keep
pace with miniaturization and other advances in information delivery systems,
conventional cathode ray tube and flat panel technologies will no longer be
able to provide an acceptable range of performance characteristics,
particularly the combination of high resolution, high level of brightness and
low power consumption, required for state-of-the-art mobile computing or
personal electronic devices.
The VRD offers
solutions to many of the problems that have plagued personal display devices.
It will allow a display that is small, low cost, low power, high resolution,
bright enough to operate in an outdoor environment, and functional in either an
inclusive or see-through mode. The VRD
appears to be an ideal display for a large number of commercial, industrial,
consumer, and military applications. VRD
will pop up in cell phones and cameras, giving users an HDTV experience on the
go, and at a fraction of the power, weight, and cost required by today’s
devices.
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