Browse Prior Art Database

Light Pipe for LCD's Backlight with Prism Structure on its Narrow Edge

IP.com Disclosure Number: IPCOM000123187D
Original Publication Date: 1998-Jun-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 1 page(s) / 36K

Publishing Venue

IBM

Related People

Suzuki, M: AUTHOR

Abstract

Disclosed is a light pipe for a backlighting unit for Liquid Crystal Display Modules. Conventional design of a light pipe is as followings. The cross-section of the light pipe is wedged shape. The thicker side of the light pipe is an inlet side of a light. It has a smooth surface and rectangular to the upper side. The thinner side of the light pipe also has a smooth surface and rectangular to the upper side. To avoid the light loss, a reflection film was placed on the thinner side of the light pipe. In spite of placing a reflection film on the thinner side of the light pipe, approximately 5% of the total light were lost in this portion. Disclosed light pipe also has a wedge-shaped cross-section. On the thinner side of the light pipe, there are lots of grooves. These roves have an isosceles triangular cross-section.

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Light Pipe for LCD's Backlight with Prism Structure on its Narrow Edge

   Disclosed is a light pipe for a backlighting unit for
Liquid Crystal Display Modules.  Conventional design of a light pipe
is as followings.  The cross-section of the light pipe is wedged
shape.  The thicker side of the light pipe is an inlet side of a
light.  It has a smooth surface and rectangular to the upper side.
The thinner side of the light pipe also has a smooth surface and
rectangular to the upper side.  To avoid the light loss, a reflection
film was placed on the thinner side of the light pipe.  In spite of
placing a reflection film on the thinner side of the light pipe,
approximately 5% of the total light were lost in this portion.
Disclosed light pipe also has a wedge-shaped cross-section.  On the
thinner side of the light pipe, there are lots of grooves.  These
roves have an isosceles triangular cross-section.  Angle of the
triangle is approximately 90 degrees.  Direction of the groove is
either vertical or horizontal or whatever.  The light from the light
source is totally internally reflected at the thinner edge of the
light pipe.  There is no need of a reflection film anymore.  More
importantly, total internal reflection causes no light loss.
Approximately 5% light yield will be gained by this technology.