Optical: systems and elements – Polarization without modulation – Depolarization
Reexamination Certificate
2000-07-27
2004-10-12
Shafer, Ricky D. (Department: 2872)
Optical: systems and elements
Polarization without modulation
Depolarization
C359S490020, C359S506000, C359S599000, C313S112000, C313S116000, C362S019000
Reexamination Certificate
active
06804058
ABSTRACT:
TECHNICAL FIELD
The invention is an improved optical display and light source assembly useable therewith.
BACKGROUND
Optical displays are widely used for lap-top computers, hand-held calculators, digital watches and the like. The familiar liquid crystal (LC) display is a common example of such an optical display. The conventional LC display locates a liquid crystal and an electrode matrix between a pair of absorptive polarizers. In the LC display, portions of the liquid crystal have their optical state altered by the application of an electric field. This process generates the contrast necessary to display “pixels” of information in polarized light.
For this reason the traditional LC display includes a front polarizer and a rear polarizer. Typically, these polarizers use dichroic dyes which absorb light of one polarization orientation more strongly than the orthogonal polarization orientation. In general, the transmission axis of the front polarizer is “crossed” with the transmission axis of the rear polarizer. The crossing angle can vary from zero degrees to ninety degrees. The liquid crystal, the front polarizer and rear polarizer together make up an LCD assembly.
LC displays can be classified based upon the source of illumination. “Reflective” displays are illuminated by ambient light that enters the display from the “front.” Typically a brushed aluminum reflector is placed “behind” the LCD assembly. This reflective surface returns light to the LCD assembly while preserving the polarization orientation of the light incident on the reflective surface.
It is common to substitute a “backlight” assembly for the reflective brushed aluminum surface in applications where the intensity of the ambient light is insufficient for viewing. The typical backlight assembly includes an optical cavity and a lamp or other structure that generates light. Displays intended to be viewed under both ambient light and backlit conditions are called “transflective.” One problem with transflective displays is that the typical backlight is not as efficient a reflector as the traditional brushed aluminum surface. Also the backlight randomizes the polarization of the light and further reduces the amount of light available to illuminate the LC display. Consequently, the addition of the backlight to the LC display makes the display less bright when viewed under ambient light.
Therefore, there is a need for a display which can develop adequate brightness and contrast under both ambient and backlight illumination.
SUMMARY
One aspect of the present invention relates to a light source for use in displays, wherein the light source comprises an electroluminescent panel having a light generating layer. The light source also comprises a reflective polarizer, where the reflective polarizer is preferably polymeric and birefringent. The reflective polarizer transmits light of a first polarization and reflects light of a second polarization back to the light generating layer. The light generating layer diffusely reflects and randomizes the polarization state of the reflected light and recirculates the reflected light back to the reflective polarizer.
REFERENCES:
patent: 540768 (1895-06-01), Western
patent: 1610423 (1926-12-01), Cawley
patent: 2123901 (1938-07-01), Land
patent: 2123902 (1938-07-01), Land
patent: 2158130 (1939-05-01), Land
patent: 2492809 (1949-12-01), Marks
patent: 2604817 (1952-07-01), Schupp
patent: 2776598 (1957-01-01), Dreyer
patent: 2887566 (1959-05-01), Marks
patent: 3124639 (1964-03-01), Kahn
patent: 3213753 (1965-10-01), Rogers
patent: 3423498 (1969-01-01), Lefevre
patent: 3480502 (1969-11-01), Schrenk
patent: 3498873 (1970-03-01), Schrenk
patent: 3528723 (1970-09-01), Rogers
patent: 3556635 (1971-01-01), Schrenk et al.
patent: 3565985 (1971-02-01), Schrenk et al.
patent: 3600587 (1971-08-01), Smith
patent: 3610729 (1971-10-01), Rogers
patent: 3631288 (1971-12-01), Rogers
patent: 3647612 (1972-03-01), Schrenk et al.
patent: 3711176 (1973-01-01), Alfrey, Jr. et al.
patent: 3712706 (1973-01-01), Stamm
patent: 3746485 (1973-07-01), Schrenk
patent: 3759647 (1973-09-01), Schrenk et al.
patent: 3773882 (1973-11-01), Schrenk
patent: 3801429 (1974-04-01), Schrenk et al.
patent: 3829680 (1974-08-01), Jones
patent: 3847585 (1974-11-01), Chisholm
patent: 3860036 (1975-01-01), Newman, Jr.
patent: 3876285 (1975-04-01), Schwarzmüller
patent: 3912921 (1975-10-01), Howe et al.
patent: 4025688 (1977-05-01), Nagy et al.
patent: 4094947 (1978-06-01), Alfrey, Jr. et al.
patent: 4162343 (1979-07-01), Wilcox et al.
patent: 4190832 (1980-02-01), Mohler
patent: 4212048 (1980-07-01), Castleberry
patent: 4254002 (1981-03-01), Sperling et al.
patent: 4268127 (1981-05-01), Oshima et al.
patent: 4310584 (1982-01-01), Cooper et al.
patent: 4315258 (1982-02-01), McKnight et al.
patent: 4427741 (1984-01-01), Aizawa et al.
patent: 4446305 (1984-05-01), Rogers et al.
patent: 4520189 (1985-05-01), Rogers et al.
patent: 4521588 (1985-06-01), Rogers et al.
patent: 4525413 (1985-06-01), Rogers et al.
patent: 4540623 (1985-09-01), Im et al.
patent: 4542449 (1985-09-01), Whitehead
patent: 4586790 (1986-05-01), Umeda et al.
patent: 4590119 (1986-05-01), Kawakami et al.
patent: 4643529 (1987-02-01), Hosonuma et al.
patent: 4659523 (1987-04-01), Rogers et al.
patent: 4660936 (1987-04-01), Nosker
patent: 4678285 (1987-07-01), Ohta et al.
patent: 4720426 (1988-01-01), Englert et al.
patent: 4756953 (1988-07-01), Utsumi
patent: 4791540 (1988-12-01), Dreyer, Jr. et al.
patent: 4796160 (1989-01-01), Kahn
patent: 4796978 (1989-01-01), Tanaka et al.
patent: 4797308 (1989-01-01), Mattin
patent: 4798448 (1989-01-01), van Raalte
patent: 4799772 (1989-01-01), Utsumi
patent: 4805984 (1989-02-01), Cobb, Jr.
patent: 4824882 (1989-04-01), Nakamura et al.
patent: 4840463 (1989-06-01), Clark et al.
patent: 4883341 (1989-11-01), Whitehead
patent: 4896942 (1990-01-01), Onstott et al.
patent: 4896946 (1990-01-01), Suzuki et al.
patent: 4906068 (1990-03-01), Olson
patent: 4917465 (1990-04-01), Conner et al.
patent: 4937134 (1990-06-01), Schrenk et al.
patent: 4952023 (1990-08-01), Bradshaw et al.
patent: 4974946 (1990-12-01), Solomon
patent: 4989076 (1991-01-01), Owada et al.
patent: 5009472 (1991-04-01), Morimoto
patent: 5042921 (1991-08-01), Sato et al.
patent: 5056888 (1991-10-01), Messerly et al.
patent: 5056892 (1991-10-01), Cobb, Jr.
patent: 5059356 (1991-10-01), Nakamura et al.
patent: 5061050 (1991-10-01), Ogura
patent: 5089318 (1992-02-01), Shetty et al.
patent: 5093739 (1992-03-01), Aida et al.
patent: 5094788 (1992-03-01), Schrenk et al.
patent: 5094793 (1992-03-01), Schrenk et al.
patent: 5095210 (1992-03-01), Wheatley et al.
patent: 5103337 (1992-04-01), Schrenk et al.
patent: 5122905 (1992-06-01), Wheatley et al.
patent: 5122906 (1992-06-01), Wheatley
patent: 5124841 (1992-06-01), Oishi
patent: 5126880 (1992-06-01), Wheatley et al.
patent: 5134516 (1992-07-01), Lehureau et al.
patent: 5138474 (1992-08-01), Arakawa
patent: 5139340 (1992-08-01), Okumura
patent: 5149578 (1992-09-01), Wheatley et al.
patent: 5157526 (1992-10-01), Kondo et al.
patent: 5159478 (1992-10-01), Akiyama et al.
patent: 5166817 (1992-11-01), Ota et al.
patent: 5175030 (1992-12-01), Lu et al.
patent: 5188760 (1993-02-01), Hikmet et al.
patent: 5189538 (1993-02-01), Arakawa
patent: 5194975 (1993-03-01), Akatsuka et al.
patent: 5200843 (1993-04-01), Karasawa et al.
patent: 5202074 (1993-04-01), Schrenk et al.
patent: 5202950 (1993-04-01), Arego et al.
patent: 5210548 (1993-05-01), Grabowski
patent: 5211878 (1993-05-01), Reiffenrath et al.
patent: 5217794 (1993-06-01), Schrenk
patent: 5221982 (1993-06-01), Faris
patent: 5233465 (1993-08-01), Wheatley et al.
patent: 5234729 (1993-08-01), Wheatley et al.
patent: 5235443 (1993-08-01), Barnik et al.
patent: 5237446 (1993-08-01), Takahashi
patent: 5238738 (1993-08-01), Miller
patent: 5245456 (1993-09-01), Yoshimi et al.
patent: 5255029 (1993-10-01), Vogeley et al.
patent: 5262894 (1993-11-01), Wheatley et al.
patent: 5269995 (1993-12-01), Ramanathan et al.
patent: 5278680 (1994-01-01), Karasawa et al.
patent: 5278694 (1994-
Jensen Stephen C.
Shafer Ricky D.
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