Browse Prior Art Database

Backlight for Transparent Liquid Crystal Display

IP.com Disclosure Number: IPCOM000101028D
Original Publication Date: 1990-Jun-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Kimura, Y: AUTHOR [+2]

Abstract

Disclosed is a low weight and compact fluorescent lamp backlight system for an LCD (liquid crystal display). The backlight system is applicable to a transmissive type LCD. This system uses mirror reflection from the surface of a cylindrical film and diffuse reflection from a reflector to obtain good luminance uniformity.

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Backlight for Transparent Liquid Crystal Display

       Disclosed is a low weight and compact fluorescent lamp
backlight system for an LCD (liquid crystal display).  The backlight
system is applicable to a transmissive type LCD. This system uses
mirror reflection from the surface of a cylindrical film and diffuse
reflection from a reflector to obtain good luminance uniformity.

      A cross sectional view of the LCD system is shown in the
figure.  The backlight system consists of a clear (low absorption)
cylindrical film 1, two straight fluorescent lamps 2, two rear lamp
reflectors 3, and a reflector or a piece of paper 4.  Luminance of
the back light should have nearly the same luminance at all display
areas.  Thus, the shape of cylindrical film should be specifically
adjusted for luminance characteristics.

      The light emitted from the fluorescent is lighting the film and
the reflector, as shown in the figure (arrow a, b). Reflected light
waves from the film make equal angles with, and lie in the same plane
as, a line perpendicular to the surface of the film (arrow c).  On
the surface of the reflector, light is reflected in all directions
(arrow d). It is a partially diffused light.  As a result, the light
from the fluorescent lamp can shine on the center of the
paper/reflector, and luminance on the LCD is constant at all display
areas.

      In this LCD, there is no diffuser between the reflector (paper)
and the liquid crystal cell.  An imag...