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Polarized Backlight for Liquid Crystal Display

IP.com Disclosure Number: IPCOM000100992D
Original Publication Date: 1990-Jun-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 64K

Publishing Venue

IBM

Related People

Suzuki, M: AUTHOR [+4]

Abstract

Disclosed is a backlight device for a transmissive liquid crystal display. This device emits a polarized light whose polarizing axis is parallel with that of a polarizer located on one side of a liquid crystal cell and near the backlight so that the light can pass through the polarizer more than a non-polarized light.

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This is the abbreviated version, containing approximately 74% of the total text.

Polarized Backlight for Liquid Crystal Display

       Disclosed is a backlight device for a transmissive liquid
crystal display.  This device emits a polarized light whose
polarizing axis is parallel with that of a polarizer located on one
side of a liquid crystal cell and near the backlight so that the
light can pass through the polarizer more than a non-polarized light.

      Light which has no polarization from a backlight into the
liquid crystal cell has uniform electromagnetic field for 360
degrees.  Theoretically, 50 percent of electromagnetic field is
absorbed and 50 percent is transmitted by the polarizer.  In
actuality, 58 percent of electromagnetic field is absorbed and 42
percent is transmitted.

      With reference to Fig. 1, the backlight disclosed herein
consists of fluorescent lamps 1, an acrylic transparent light guide
2, an acrylic translucent diffuser 3, and an acrylic sheet 4 which
has an indented cross-section.  Light emitted from the fluorescent
lamps 1 is conducted through the light guide 2 by the law of total
reflection and is scattered by the diffuser 3 for the purpose of
uniform luminance.  The acrylic sheet 4 not only optimizes the
emissing direction of light by varying the indentation angle but also
polarizes the light.  Fig. 2 shows a rotation angle versus luminance
measured with a polarizing prism.  In this case, the acrylic sheet
has a indentation angle of 90 degrees.  This chart shows that
luminance changes according to...