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WO1994011766A1 - Polariseur reflechissant - Google Patents

Polariseur reflechissant Download PDF

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Publication number
WO1994011766A1
WO1994011766A1 PCT/US1993/010801 US9310801W WO9411766A1 WO 1994011766 A1 WO1994011766 A1 WO 1994011766A1 US 9310801 W US9310801 W US 9310801W WO 9411766 A1 WO9411766 A1 WO 9411766A1
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WO
WIPO (PCT)
Prior art keywords
light
polarizer
conductors
reflective
display
Prior art date
Application number
PCT/US1993/010801
Other languages
English (en)
Inventor
Randy M. Maner
Larry A. Nelson
Original Assignee
Honeywell Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Honeywell Inc. filed Critical Honeywell Inc.
Publication of WO1994011766A1 publication Critical patent/WO1994011766A1/fr

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
    • G02B5/3058—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state comprising electrically conductive elements, e.g. wire grids, conductive particles

Definitions

  • the present invention relates to the field of back lit displays and, more particularly, to displays including, for example, LCD, ferroelectric displays, signboards, projection displays, and other similar illuminated display devices and systems.
  • Display including, for example, LCD, ferroelectric displays, signboards, projection displays, and other similar illuminated display devices and systems.
  • Prior art back lit displays suffer from poor luminance uniformity, insufficient luminance and excessive power consumption which generates unacceptably high levels of heat in and around the display.
  • Prior art displays also exhibit a non-optimal environmental range due to dissipation of energy in temperature sensitive components .
  • Prior art displays also feature excessively large back light assemblies.
  • Increasing the luminance of displays such as, for example, liquid crystal displays (LCDs) has been accomplished in the prior art by increasing the electrical power for illuminating the back light.
  • LCDs liquid crystal displays
  • TN AMLCD (TN AMLCD) is illustrated in Figure 1.
  • a typical display 10 usually includes display drive electronics
  • a fluorescent lamp 12 a diffuser 16 a first polarizer 18, a spatial light modulator 20, a color filter and black matrix 22 and a second polarizer 24 adjacent the front surface of the display 26.
  • the back light produced by the fluorescent lamp 12 is diffused to achieve uniformity and generally directed according to viewing angle requirements .
  • the back light is also polarized. Light which is incident on the back of the display surface is twisted and passed through the spatial light modulator 20 or absorbed in crossed polarizers so as to form an image for the viewable front surface 26.
  • the viewable surface of the TN AMLCD display may be perceived as not bright enough for avionic applications.
  • a bright back light on the order of 7000 fL surface luminance, may be constructed by using a fluorescent lamp 12 having maximum bulb area and driving it at maximum cathode current.
  • additional brightness may be obtained by interleaving lamps.
  • the main thrust of the aforedescribed techniques is to increase the lamp power density of the back lit area as much as possible.
  • fluorescent lamps of this type are efficient, they still consume considerable amounts of power in order to produce light.
  • the resulting high luminance of the fluorescent lamps increases the amount of electrical power and generates excessive heat .
  • the use of high powered lamps dramatically reduces battery life or increases the size of batteries required for operation.
  • Figures 2A and 2B show measurements of a TN AMLCD image surface which exhibits the absorbance of light energy for collimated light at 632.8 nm. These measurements were taken with a HeNe laser linearly polarized excitation source which was spatially under sampled by the AMLCD's apertures. The laser source's polarization was aligned to peak measured data. Radiation that is neither reflected nor transmitted is absorbed, thus for light at 10 degrees horizontal angle of incidence as shown by curves 204, 206, about 9 % of the incident light is transmitted.
  • Curves 200, 202 indicate that about 10 - 11 % of incident light at a 10 degree horizontal angle of incidence is reflected. The data shows that about 80 % of the light is absorbed by conversion to heat energy. For typical color TN AMLCD only between 2 and 4 % of white unpolarized light of a fluorescent back light passes out the front surface of the display. This is a problem for the visual performance of the display and it limits the environmental range of the display due to the inability to dissipate the excess heat energy. Excess power dissipation also increases the cost of operation for the display.
  • Another technique is to decrease the space on the display surface which is used for optically inactive elements, such as row and column address structure or transistor area. Efforts in this direction have decreased yield in the manufacturing of displays, and/or limited pixel density, causing poor image quality.
  • a reflective polarizer includes a grid of conductors arranged in parallel to each other and suitably spaced apart so as to transmit light in the visible spectrum having a first polarization and reflect light in the visible spectrum having a second polarization.
  • the conductors may be metal wires having a width of at most about .1 micrometers.
  • the wires may be spaced apart by about .3 micrometers or less.
  • the metal wires may be made from aluminum, copper, silver, gold, nickel or platinum material.
  • the invention provides a reflecting polarizer for transmitting a light having a first polarization and reflecting a light having a second polarization for use with a radiant energy conservation LCD display including a cavity having a highly reflective, diffusing interior surface.
  • a back light is mounted within the cavity.
  • a filter is located forward of the back light for transmitting filtered light of specified frequencies and for reflecting out of band light rather than absorbing it.
  • the filter includes the reflecting polarizer.
  • a reflective polarizer made according to the present invention may advantageously be placed between a back light and a rear polarizer where the rear polarizer is an absorbing polarizer. Light reflected off the address structure mask or the color filters may advantageously pass through the reflecting polarizer and return to the back light cavity.
  • Incident light polarized in the same axis as the polarization axis of the rear absorbing polarizer may advantageously be transmitted from the back light cavity to the display.
  • Incident light of the complementary polarization may advantageously be returned to the back light cavity where it may advantageously be reflected back toward the reflecting polarizer. It is important that the lighting cavity's reflecting surface scramble the polarization of the incident light so that on each circuit between the reflecting polarizer and the reflecting cavity, at least one-half of the light is polarized for possible transmission through the display surface.
  • Figure 1 schematically illustrates the construction of a typical prior art back lit twisted neumatic active matrix liquid crystal display (TN AMLCD) .
  • Figures 2A and 2B show measurements of a TN AMLCD image surface which exhibits the absorbance of light energy for collimated light at 632.8 nm.
  • Figure 3 graphically shows the opportunity for increased display luminance based upon changing the elements of the display so that they accomplish their function in a manner which conserves radiant energy.
  • Figure 4 shows the placement of color filters made from gels in an assembly which was substantially absorbing made from photographic tape having 4 % reflectivity placed on a 0.060 inch soda lime glass substrate.
  • Figure 5 shows the spectral characteristics of Kodak Wratten gel filters.
  • Figure 6 shows the spectral characteristics of dichroic filters used in one aspect of the invention to reflect out-of-band light into the back light assembly while transmitting light which falls within the pass band of the filter.
  • Figure 7 illustrates one example of a reflecting back light cavity as contemplated by the invention.
  • Figure 8 illustrates an alternative front glass for one embodiment of the invention which was constructed using color separation filters placed in a film matrix.
  • Figure 9 graphically shows a measured reduction in light as a function of exposed surface area of a particular absorber as commonly found in LCD displays .
  • FIG. 10 schematically illustrates an LCD utilizing a reflective polarizer in accordance with one aspect of the invention.
  • Figure 11 schematically illustrates increased contrast for traditional LCDs under high ambient illumination.
  • Figure 12 is a simplified illustration of loss of an LCD's traditional advantage under high ambient illumination.
  • Figure 13 graphically illustrates experimentally measured relative absorption properties of each of a fluorescent bulb, diffuser, and polarizer.
  • LCD liquid crystal display
  • conventional LCDs around 90% of the light energy created in the fluorescent lamps used for back lighting is converted to heat through absorption by materials within the display.
  • the interaction of radiant energy with materials is described by transmission, reflection, or absorption.
  • Experiments conducted at Honeywell Inc., Defense Avionics Systems Division in Albuquerque New Mexico used a commercially available integrating sphere to measure absorption of various materials found in typical back lighted displays.
  • Such materials include, for example, fluorescent bulbs, diffusers, and other components.
  • the total radiant energy which exits an integrating sphere must equal the sum of the input radiant energy minus the amount of energy lost to absorption.
  • calibration of the loss can be done using a known luminous source.
  • Such sources are well known in the art.
  • the integrating sphere need not be perfect in order to be characterized and used. In fact the only requirement is that the sphere be calibrated to account for loss by absorption.
  • the back light assembly for an LCD may be regarded as an integrating sphere with a huge exit aperture.
  • the back light assembly of an LCD contains materials with less than ideal reflective properties. The goal of the experiments was to characterize these materials to develop an understanding of their effect on the efficiency of our back light cavity.
  • the Honeywell light absorption experiments measured the decrease in light as the amount of absorptive material was increased within a luminance integrating sphere purchased from Hoffman Engineering model number LS-65-8C.
  • Light absorbing material was made in two different shapes, spheres and disks. Each shape was fabricated from metal and made in various diameters which were sandblasted to achieve a rough texture and painted flat black to achieve approximately 100% absorption of incident visible light. Each sphere or disk was individually placed inside of the integrating sphere, and the light was measured through the exit aperture of the integrating sphere using a Pritchard 1980A photometer. Figure 9 shows the measured reduction in light intensity as a function of the exposed surface area of the particular absorber.
  • the vertical axis 90 of Figure 9 is the measured luminance plotted as a percentage of the integrating sphere's light output normalized to 100% for the condition where no additional absorptive materials were added to the integrating sphere.
  • the horizontal axis 92 of Figure 9 is the surface area of the added absorber divided by the internal surface area of the integrating sphere expressed as a percentage. The horizontal axis 92 was selected to allow for extrapolation of the measured data to LCD lighting cavity applications .
  • the squares 94 on Figure 9 represent the measured data for sphere shaped absorbers, and the circles 96 represent the data for the disk shaped absorbers.
  • a first curve 98 was plotted for the measured sphere data and a second curve 100 was plotted for the measured disk data. The difference between the first and second curves indicates the effect of absorber shape within the experimental apparatus.
  • the continuous curve 98 underlying the measured disk data shown in Figure 9 is predicted data for the integrating sphere with an average internal reflectance of 96.5%.
  • the basis for calculations used in the experiment is found in two references Illumination Engineering, J. B. Murdoch, 1985, pp 45-48, and Applied Optics, Volume I, L. Levi, 1968, pp 31-32.
  • Murdoch presents an equation which calculates the exitance at the integrating sphere's exit aperture.
  • the exitance having units of lumens per unit area and the luminance, having units of candela per unit area, are directly proportional at the integrating sphere's exit aperture.
  • Murdoch's equation is
  • E (p ⁇ ) / (A t (1 - p) )
  • E the exitance
  • p the average reflectance of the sphere
  • ⁇ the luminous flux of the sphere's light source
  • a t the internal surface area of the integrating sphere.
  • the average reflectance (p) of the sphere was decreased.
  • the reflectance of the sphere is dependent upon two factors :
  • the reflectance of the sphere with no absorbers added can be estimated using the following equation p - m - ⁇ A o / A t ) where A o is the area of the sphere's exit aperture. Loss due to the exit aperture must be normalized by internal reflecting area because it determines the flux density at the exit aperture.
  • a o is the exposed surface area of the absorber.
  • a a is equal to the surface area of the sphere and for the disks it is equal to the area of one side of the disk.
  • Figure 3 graphically exhibits the extension of this energy loss model to the conditions expected for a typical avionics display.
  • the bottom curve 310 reflects the operating condition for a conventional display.
  • the other curves 302 - 308 represent the potential gains associated with the addition of the proposed perfect reflective optical components.
  • curve 308 represents the addition of a reflective aperture matrix.
  • Curve 306 represents the addition of reflective polarizers to the display of curve 308.
  • Curve 304 represents the addition of reflective color filters to the display of curve 308.
  • Curve 302 represents a display having reflective aperture masks, reflective color filters and a reflecting polarizer such as a wire grid polarizer.
  • an effective exit aperture is defined as a component wherein light which is completely absorbed can be regarded as having passed out an exit aperture. Substituted materials which reflect light which was absorbed can be modeled by reducing exit aperture area.
  • the lighting cavity's size was assumed to be 6 x 8 x 2.3 inches to calculate the internal surface area of the integrating cavity (A t )
  • the average reflectance of the cavity, p m was assumed to be 1.0, and the horizontal axis variable, (A / A t ) , is expressed as a percentage on Figure 3 ranging from 0% to 10%.
  • the bottom curve 310 was calculated with A o equal to the area of the display surface, about 48 sq. in. This assumes that all light incident on the rear polarizer of the LCD module is either absorbed or transmitted.
  • the normalized luminance of 100% is established as a reference based on the prior art exhibited by curve 310.
  • Curve 306 reflects the potential gain associated with adding a wire grid polarizer to an LCD module with a reflective row and column address structure.
  • the effective aperture is decreased to 13.2 square inches based upon the assumption that the light previously lost in the rear polarizer is now recovered by reflection within the lighting cavity. Previously the lost light amounted to about 50% of the total light produced by the back lights.
  • the absorption of each component can be quantitatively estimated. This can be accomplished by repeating the integrating sphere experiment using the components or representative pieces of the components to measure the light loss . From this measured data an equivalent black disk surface area can be determined. This equivalent surface area can then be scaled by the ratio of the proper size for the material which will be present within the lighting cavity divided by the size of the measured piece.
  • Table 1 hereinbelow shows the light loss for sections of an ATSD D size fluorescent lamp where the bulb's inner diameter is 0.476". For each lamp length, the lamp was fitted with end caps made of Spectralon (TM) prior to insertion into the integrating sphere. The length shown in table 1 is the distance between the two Spectralon end caps . TABLE 1
  • Dashed line 312 at 2.88% represents the amount of relative absorption associated with a fluorescent lamp having a 15 mm diameter, and 1226.6 mm length.
  • a section of a milky white diffuser was placed inside of the integrating sphere and the light loss was measured.
  • the diffuser piece had an exposed surface area of 1.565 square inches.
  • the measured loss was 5.96% for this piece.
  • a black disk with a surface area of 0.3219 square inches will exhibit this percentage of loss from the Hoffman Engineering integrating sphere.
  • Scaling the loss for a diffuser which is 48 square inches and placed inside of the lighting cavity gives 6.15% of absorptive material relative to the lighting cavity. Taken together the fluorescent bulb and the diffuser result in 9.03% of absorptive material within the lighting cavity.
  • Curve 304 assumes the aperture is equal to the area of the red pixels on the display surface.
  • the effective aperture is reduced by a factor of 2 because the loss associated with the rear polarizer may advantageously be approximately 50 %.
  • a reflecting back light cavity 700 was constructed using Spectralon (TM) material to coat inside wall 706.
  • Spectralon (TM) was selected because of its excellent diffuse reflectance properties across the visible spectrum.
  • a fluorescent bulb 720 was installed to provide a representative source of illumination.
  • a front glass 710 was constructed with 1 by 1 inch pixels in a 6 x 8 inch active area 702.
  • Figure 4 shows the placement of color filters 402 made from Kodak Wratten gels in a front glass assembly 400 which was substantially absorbing made from photographic tape placed on a 0.060 inch soda lime glass substrate.
  • the photographic tape had 4% reflectivity. This is intended to simulate the approximate aperture ratio (51 %) and absorbance of matrix displays with RGGB color filter structure and about 170 pixels per inch aperture density.
  • Such a front glass surface represents the conventional approach to manufacturing flat panel displays, in this case with a flat field white image displayed.
  • FIG. 5 shows the spectral characteristics of the Kodak Wratten gel filters used in the construction of the front glass assembly 400.
  • the vertical axis 500 represents transmittance and the horizontal axis 502 represents wave length in nanometers.
  • Curves 504, 506 and 508 respectively represent blue, green and red light transmittance characteristics. Note the substantial overlap area at point 510 between the blue and green filters. Such an overlap blurs color distinctions and is undesirable because of the resultant de-saturated primary colors.
  • an alternative front glass 800 was constructed using color separation filters 802 available from OCLI of California placed in a commercially available 3M brand Silverlux (TM) film matrix 806 which has greater than 95% reflectivity. All surfaces, generally designated 804, which are not within RGB squares are reflective of incident light arriving from the back lit side of the glass 800.
  • TM Silverlux
  • Figure 6 shows the spectral characteristics of the OCLI filters 802. Note that the vertical axis 600 represents transmittance and the horizontal axis 602 represents wave length in nanometers. Curves 604, 606 and 608 respectively represent blue, green and red light transmittance characteristics. The overlap area at point 610 between the blue and green filters is substantially less than for the absorbing glass assembly 400 as graphically illustrated in Figure 5 at point 510. These filters are of dichroic construction, so they reflect out-of-band light into the back light assembly while transmitting light which falls within the pass band of the color filter.
  • FIG. 7 Another front glass assembly was constructed to hold an absorbing polarizer Sanritsu model 9218.
  • Each of the front glass assemblies 400, 800 were placed in front of the back light assembly as shown in Figure 7. Measured Increases Due to Utilization of Radiant Energy Conservation
  • a macro scale model was constructed to provide a means of measuring the increased display luminance for a constant luminous input such as the lamp 720.
  • the model is considered to be a "macro scale" model because the glass plates 710 were made having approximately 170 times the aperture density of an LCD designed for a typical avionic application.
  • the macro scale model had individual color apertures which were approximately one inch square distributed on a 6 x 8 inch glass substrate in a RGGB mosaic.
  • the lighting cavity 700 itself was the same size as the lighting cavity planned for use in an avionics application.
  • the first method of measurement used a calibrated 1980A Pritchard photometer located normal to the display surface and focused on a single green aperture of the glass plate under measurement. This method is referred to as the "green pixel" method hereinbelow.
  • the second method utilized a 40 inch diameter integrating sphere to collect the radiant energy emitted by the display surface in all directions. By affixing the face of the display to the sphere's large aperture such that all of the radiant energy from the display surface was emitted into the integrating sphere's cavity which is coated with a diffuse, highly reflective material such as Spectralon (TM) .
  • TM Spectralon
  • a glass plate made of absorptive color filters, namely, Kodak Wratten gels, and black photographic tape was used to represent present art construction techniques for LCD's.
  • the black photographic tape was used to represent the opaque row and column interconnection area on an LCD.
  • the glass plate is referred to hereinbelow as the absorptive glass plate .
  • a second glass plate as was constructed from reflective color filters, namely, OCLI' s color separation filters, and reflective tape, namely, 3M Silverlux (TM) tape._
  • the second glass plate was utilized to simulate the construction of a display utilizing the concepts described in this patent application.
  • the second glass plate included reflective color filters and a reflective aperture mask.
  • Box is defined to be the lighting cavity 700, the light source 720 and the electronics required to activate the light source.
  • Ab ⁇ is defined to be the absorptive glass plate described above.
  • Ref is defined to be the reflective glass plate described above.
  • Pol is defined to be the absorptive polarizer (Sanritsu model 9218) glass plate described above.
  • the order of glass plate components listed below describes the physical location in front of the light source which was used for the particular measurement .
  • Box + Abs + Ref indicates the absorptive plate was placed between the reflective glass plate and the light source within the box (i.e., the viewer saw the reflective plate's surface) .
  • Any polarizer which has minimal absorption of the incident radiant energy can be used to increase AMLCD luminous efficacy if it is used as described herein.
  • a polarizer may be constructed from a grid of thin conductive wires which are aligned parallel to one another. The approximate width of the conductors needed to polarize the visible spectrum is 0.1 micrometers. These conductive wires must be aligned parallel to one another with a spacing of approximately 0.3 micrometers between wires .
  • the reflective polarizer described in this patent application will offer the desirable feature of having a good extinction ratio for a broad angle of incidence of radiance.
  • the most desirable feature is reflection of the incident radiation which is not aligned with the reflective polarizer's transmissive polarization axis. This presents the opportunity of returning this energy to the system by redirecting and "re-polarizing" the radiation such that it may pass through the reflective polarizer and the traditional polarizers to the display's observer.
  • no wire grid polarizer has been constructed for operation in the visible spectrum.
  • the wire grid polarizer is only one type of reflective polarizer which conserves radiant energy by returning untransmitted energy through reflection and other equivalent devices may be employed to accomplish the objectives of the instant invention.
  • Wire grids have traditionally functioned as polarizers where their application has migrated upward along the electromagnetic spectrum as the technological improvements enabled devices with progressively smaller dimensions. This progression has continued for two reasons . The first reason is driven by the need for finer and finer detailed metallic structures for use within the semiconductor industry. Secondly, the high conductivity of metals has been maintained at the wavelengths of radiation previously considered. The conductivity of commonly available metals will decrease in the visible spectrum making this more of a limiting characteristic. Wire grid polarizers manufactured in accordance with the present invention exhibit good extinction ratios over a broad spectrum as is shown, for example, in Figure 3 of "The Wire Grid as a Near-Infrared Polarizer" by G. Bird and M.
  • a wire grid polarizer made in accordance with the invention may be manufactured using well-known lithographic techniques such as employing, for example, an electron beam process for etching. Typical pitch between conductors for a reflective wire grid polarizer which will work in the visible spectrum should be approximately M the wavelength of the radiation ( ⁇ .2 ⁇ m for green light) .
  • the apparatus shown in Figure 10 includes an LCD display 100 including a conventional LCD assembly 102, an absorbing rear polarizer 104, a reflecting wire grid polarizer 106, a backlight cavity 108, and a fluorescent light source 110 of known serpentine construction.
  • the conventional LCD assembly may include liquid crystal cells, a polarizer and a display glass.
  • Ray 112 which extends from the fluorescent bulb source to surface 120 of the reflecting wire grid polarizer 106, represents emitted light from the fluorescent light source 110 having both p and s polarization.
  • Ray 114 which extends from surface 120 to back plane 122, represents reflected light of s polarization only.
  • Ray 116 which extends from the wire grid polarizer 106 to outside of the view surface 102, represents transmitted light of p polarization only.
  • the backlight cavity is advantageously light tight and coated with diffusely reflective material.
  • the reflected light of ray 114 is scrambled by the diffusely reflective material 107 which coats the backlight cavity 108, including back plate 122.
  • the polarization axes of the wire grid polarizer 106 are aligned with the polarizing axes of the absorbing polarizer 104.
  • the .reason for aligning a reflective polarizer with an absorbing rear polarizer as shown in Figure 10 may be 'better understood by examining an LCD's inherent ability to increase its contrast under high ambient illumination as illustrated by Figures 11 and 12.
  • FIG. 11 a simplified illustration of increased contrast for traditional LCDs under high ambient illumination is schematically illustrated. Shown is a reflective backlight cavity 108, a first absorbing polarizer 130, a transmissive liquid crystal cell 132, a non-transmissive liquid crystal cell 134, and a second absorbing polarizer 136.
  • the liquid crystal cells are advantageously polarization twisted in a well known manner.
  • the first absorbing polarizer 130 transmits p polarized light.
  • the second absorbing polarizer 136 transmits s polarized light.
  • Ray 140 represents ambient illumination which enters the second absorbing polarizer and is reflected out along ray 144 after being reflected off of the backlight cavity 108.
  • Ray 142 represents ambient illumination absorbed in the first polarizer 130.
  • FIG 12 a simplified illustration of loss of an LCD's traditional advantage under high ambient illumination is shown.
  • a reflective polarizer 150 is used here between the back light cavity and the liquid crystal cells. Shown in combination are a reflective backlight cavity 108, a reflective polarizer 150, a transmissive liquid crystal cell 132, a non- transmissive liquid crystal cell 134, and an absorbing polarizer 136.
  • the liquid crystal cells are polarization twisted in a well known manner.
  • the reflective polarizer 150 transmits p polarized light.
  • the absorbing polarizer 136 transmits s polarized light.
  • Ray 152 represents ambient illumination which enters the absorbing polarizer and is reflected out along ray 154 after being reflected off of the backlight cavity 108.
  • Ray 156 represents ambient illumination reflected by the reflecting polarizer 150 to an observer along ray 158, thus eliminating a traditional LCD's increased contrast under high ambient illumination.
  • the reflecting polarizer is aligned with the traditional absorbing rear polarizer to maintain an LCD's inherent increased contrast in ambient illumination.
  • Reflective metal used in the reflecting wire grid polarizer must maintain high conductivity over visible spectrum to ensure performance independent of wavelength. It is advantageous to vary the duty cycle of the reflecting polarizer by minimizing the width of the reflective portion to provide high transmission. Further improvement in the wire grid polarizer may be achieved by use of very conductive materials to achieve good extinction ratios and broad operable angle. Such a reflecting polarizer results in high effective transmission through an LCD when combined with an efficient reflective back light cavity.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Devices For Indicating Variable Information By Combining Individual Elements (AREA)

Abstract

Un polariseur réfléchissant (150) comprend une grille de conducteurs (106) agencés en parallèle les uns par rapport aux autres et correctement espacés de manière à transmetter la lumière (112) dans le spectre visible ayant une première polarisation (116), et réfléchir la lumière dans le spectre visible ayant une seconde polarisation (114). Les conducteurs (106) peuvent être des fils métalliques ayant une largeur au plus d'environ 0,1 micromètre. Les fils peuvent être espacés d'environ 0,3 micromètre au moins. Les fils métalliques peuvent être en aluminium, en cuivre, en argent, en or, en nickel ou en platine.
PCT/US1993/010801 1992-11-09 1993-11-09 Polariseur reflechissant WO1994011766A1 (fr)

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US97379992A 1992-11-09 1992-11-09
US07/973,799 1992-11-09

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WO1994011766A1 true WO1994011766A1 (fr) 1994-05-26

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Cited By (9)

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US6268961B1 (en) 1999-09-20 2001-07-31 3M Innovative Properties Company Optical films having at least one particle-containing layer
US6381068B1 (en) 1999-03-19 2002-04-30 3M Innovative Properties Company Reflective projection screen and projection system
US6511204B2 (en) 1999-12-16 2003-01-28 3M Innovative Properties Company Light tube
US6785049B1 (en) 2000-01-31 2004-08-31 3M Innovative Properties Company Illumination system for reflective displays
EP1744197A3 (fr) * 2005-07-15 2007-03-14 Sanyo Electric Co., Ltd. Dispositif d éclairage et appareil d affichage vidéo du type projection
CN100383569C (zh) * 2003-11-14 2008-04-23 宫田清藏 偏振光学元件及其制造方法和使用该元件的反射光学元件
US7414784B2 (en) 2004-09-23 2008-08-19 Rohm And Haas Denmark Finance A/S Low fill factor wire grid polarizer and method of use
DE112006002940T5 (de) 2005-11-05 2008-12-11 3M Innovative Properties Co., St. Paul Optische Filme, umfassend einen hohen Brechungsindex aufweisende und antireflektierende Beschichtungen
DE112007001526T5 (de) 2006-06-30 2009-05-14 3M Innovative Properties Co., St. Paul Optischer Artikel mit einer Perlenschicht

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US3969545A (en) * 1973-03-01 1976-07-13 Texas Instruments Incorporated Light polarizing material method and apparatus
US4009933A (en) * 1975-05-07 1977-03-01 Rca Corporation Polarization-selective laser mirror
EP0004900A2 (fr) * 1978-04-25 1979-10-31 Siemens Aktiengesellschaft Procédé de réalisation de polariseurs constitués par une série de bandes conductrices parallèles, déposées sur une plaque de verre
JPS6033534A (ja) * 1983-08-04 1985-02-20 Sharp Corp 液晶表示素子
JPH0384502A (ja) * 1989-08-29 1991-04-10 Shimadzu Corp グリッド偏光子
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US3291550A (en) * 1965-04-16 1966-12-13 Polaroid Corp Metallic grid light-polarizing device
US3969545A (en) * 1973-03-01 1976-07-13 Texas Instruments Incorporated Light polarizing material method and apparatus
US4009933A (en) * 1975-05-07 1977-03-01 Rca Corporation Polarization-selective laser mirror
EP0004900A2 (fr) * 1978-04-25 1979-10-31 Siemens Aktiengesellschaft Procédé de réalisation de polariseurs constitués par une série de bandes conductrices parallèles, déposées sur une plaque de verre
JPS6033534A (ja) * 1983-08-04 1985-02-20 Sharp Corp 液晶表示素子
JPH0384502A (ja) * 1989-08-29 1991-04-10 Shimadzu Corp グリッド偏光子
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US6381068B1 (en) 1999-03-19 2002-04-30 3M Innovative Properties Company Reflective projection screen and projection system
US6268961B1 (en) 1999-09-20 2001-07-31 3M Innovative Properties Company Optical films having at least one particle-containing layer
US6511204B2 (en) 1999-12-16 2003-01-28 3M Innovative Properties Company Light tube
US6785049B1 (en) 2000-01-31 2004-08-31 3M Innovative Properties Company Illumination system for reflective displays
US6900936B2 (en) 2000-01-31 2005-05-31 3M Innovative Properties Company Illumination system for reflective displays
US7057814B2 (en) 2000-01-31 2006-06-06 3M Innovative Properties Company Illumination system for reflective displays
CN100383569C (zh) * 2003-11-14 2008-04-23 宫田清藏 偏振光学元件及其制造方法和使用该元件的反射光学元件
US7414784B2 (en) 2004-09-23 2008-08-19 Rohm And Haas Denmark Finance A/S Low fill factor wire grid polarizer and method of use
EP1855144A1 (fr) * 2005-07-15 2007-11-14 Sanyo Electric Co., Ltd. Dispositif d'éclairage et affichage vidéo du type projection
EP1744197A3 (fr) * 2005-07-15 2007-03-14 Sanyo Electric Co., Ltd. Dispositif d éclairage et appareil d affichage vidéo du type projection
US7887193B2 (en) 2005-07-15 2011-02-15 Sanyo Electric Co., Ltd. Illuminating device and projection type video display apparatus
DE112006002940T5 (de) 2005-11-05 2008-12-11 3M Innovative Properties Co., St. Paul Optische Filme, umfassend einen hohen Brechungsindex aufweisende und antireflektierende Beschichtungen
DE112007001526T5 (de) 2006-06-30 2009-05-14 3M Innovative Properties Co., St. Paul Optischer Artikel mit einer Perlenschicht

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