Browse Prior Art Database

Viewing of Low Intensity Display Units Chip Stack

IP.com Disclosure Number: IPCOM000106406D
Original Publication Date: 1993-Nov-01
Included in the Prior Art Database: 2005-Mar-21
Document File: 2 page(s) / 85K

Publishing Venue

IBM

Related People

Coteus, PW: AUTHOR [+2]

Abstract

Information displayed on a video display terminal is difficult to view when the intensity of the displayed image is much less than that of the ambient light. For example, it is very difficult to view a backlit liquid crystal display screen in full sunlight. It is desirable to provide a means of viewing dim display images, either to allow viewing in brightly lit areas or to allow use of lower power displays.

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Viewing of Low Intensity Display Units Chip Stack

      Information displayed on a video display terminal is difficult
to view when the intensity of the displayed image is much less than
that of the ambient light.  For example, it is very difficult to view
a backlit liquid crystal display screen in full sunlight.  It is
desirable to provide a means of viewing dim display images, either to
allow viewing in brightly lit areas or to allow use of lower power
displays.

      A solution to the problem is to generate the primary image as a
series of short bursts of light, with an intensity sufficient to
allow easy viewing.  For example, the backlight of a conventional
liquid crystal display may be replaced with a strobe light.  The
average display intensity produced by the strobe light is
considerably less than the ambient light, and the resultant image is
difficult to view.  The frequency of the strobe light exceeds the
flicker frequency of the eye, so that the light appears to be
continuous.

      When the image formed using strobed light is viewed through a
shutter synchronized to the strobe light, the display light intensity
is greatly enhanced over the ambient background light.  Since the
shutter is only open while the backlight is on, the viewer sees the
same image as before.  However, the amount of background light seen
is greatly diminished, by the fraction of time the shutter is in the
closed state.  Using liquid crystal electronic shutters, it should be
possible to achieve up to 1/10,000 reduction in the intensity of the
background light.  The shutter may be conveniently fitted into
eyeglasses worn by the viewer.

      It is only necessary to reduce the background light while
looking at the primary image.  At other times, for example while
looking at the keyboard of a computer, a greater amount of background
light may be desired.  One means to allow this is to provide means to
control the shutter, based on orientation.  For example, a light
source from the display may be reflected off the shuttered
eyeglasses, and received at the display.  The amount of reflected
light is sensitive to the angle of the eyeglasses with respect to the
display.  As the viewer's head is tilted to look away from the
display, th...