Browse Prior Art Database

Interframe Multiplexed Video Projection Display

IP.com Disclosure Number: IPCOM000101156D
Original Publication Date: 1990-Jul-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 1 page(s) / 38K

Publishing Venue

IBM

Related People

Jansen, LA: AUTHOR [+2]

Abstract

Disclosed is a projection display which integrated two liquid crystal displays (LCDs). These displays are used in the transmissive mode and placed such that their images coincide at a half-way mirror where the two images are combined into one. One LCD is used to display even lines, while the other is used to display odd lines. The odd and even lines are interstitially arranged so that the resulting image is constructed from two interlaced fields.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

Interframe Multiplexed Video Projection Display

       Disclosed is a projection display which integrated two
liquid crystal displays (LCDs).  These displays are used in the
transmissive mode and placed such that their images coincide at a
half-way mirror where the two images are combined into one.  One LCD
is used to display even lines, while the other is used to display odd
lines.  The odd and even lines are interstitially arranged so that
the resulting image is constructed from two interlaced fields.

      The figure shows a top view of this arrangement. Starting at
the light source at left, the light is first collimated and split
with a half-way mirror.  Half the light is used to project the even
lines of the image, while the other half is reflected by two mirrors
to project the odd lines.  Both images are optically combined with
another half- way mirror and subsequently projected via a projection
lens onto either a direct view screen or rear projection screen.

      The main advantage of this arrangement is that conventional
multiplexed line addressing can be used. Conventional twisted nematic
and supertwisted LCDs cannot easily display high content (640 x 480)
and high contrast simultaneously.  However, by interlacing two
fields, the number of lines on each display is reduced by a factor of
2. This provides for high contrast and high resolution.