Liquid crystal display projection system using multilayer optical film polarizers

• Main Authors: WEBER, MICHAEL FRANCIS, WILLETT, STEPHEN JOSEPH, OUDERKIRK, ANDREW JOHN, JONZA, JAMES MICHAEL
• Format: Patent
• Language: English
• Published: 28.05.2001
• Edition: 7
• Subjects: DEVICES OR ARRANGEMENTS, THE OPTICAL OPERATION OF WHICH ISMODIFIED BY CHANGING THE OPTICAL PROPERTIES OF THE MEDIUM OF THEDEVICES OR ARRANGEMENTS FOR THE CONTROL OF THE INTENSITY,COLOUR, PHASE, POLARISATION OR DIRECTION OF LIGHT, e.g.SWITCHING, GATING, MODULATING OR DEMODULATING; FREQUENCY-CHANGING; NON-LINEAR OPTICS; OPTICAL ANALOGUE/DIGITAL CONVERTERS; OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS; OPTICAL LOGIC ELEMENTS; OPTICS; PHYSICS; TECHNIQUES OR PROCEDURES FOR THE OPERATION THEREOF

A liquid crystal display (LCD) projection system (50) including a projection panel (52), a light source (56), and a reflector (58). The projection panel includes an LCD (60) and a polarizer (64) on one side of the LCD and a reflective polarizer (62) on the other side. The reflective polarizer is a multilayer stack of pairs (44) of adjacent material layers (41, 43). Each of the layer pairs exhibits a refractive index difference between the adjacent layers in a first direction in the plane of the reflective polarizer and exhibits essentially no refractive index difference between adjacent layers in a second direction in the plane of the reflective polarizer and orthogonal to the first direction. A quarter-wave plate (66) is secured to the reflective polarizer. Light rays from the light source either pass through the reflective polarizer, and on to the LCD, or are reflected back toward the light source, depending on their polarization. Light which is reflected by the reflective polarizer is reflected by the reflector back toward the LCD again. The use of the quarter-wave plate and the reflector help to recycle what would typically be regarded as wasted light, while at the same time reducing heat build-up within the LCD.