[go: up one dir, main page]

WO1994029765A1 - Affichage a cristaux liquides a luminosite amelioree - Google Patents

Affichage a cristaux liquides a luminosite amelioree Download PDF

Info

Publication number
WO1994029765A1
WO1994029765A1 PCT/US1994/005936 US9405936W WO9429765A1 WO 1994029765 A1 WO1994029765 A1 WO 1994029765A1 US 9405936 W US9405936 W US 9405936W WO 9429765 A1 WO9429765 A1 WO 9429765A1
Authority
WO
WIPO (PCT)
Prior art keywords
light
prismatic
polarizing layer
layer
assembly
Prior art date
Application number
PCT/US1994/005936
Other languages
English (en)
Inventor
Kevin J. Hathaway
Sanford Cobb, Jr.
Original Assignee
Minnesota Mining And Manufacturing Company
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 Minnesota Mining And Manufacturing Company filed Critical Minnesota Mining And Manufacturing Company
Publication of WO1994029765A1 publication Critical patent/WO1994029765A1/fr

Links

Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/005—Means for improving the coupling-out of light from the light guide provided by one optical element, or plurality thereof, placed on the light output side of the light guide
    • G02B6/0053—Prismatic sheet or layer; Brightness enhancement element, sheet or layer
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
    • F21V9/00—Elements for modifying spectral properties, polarisation or intensity of the light emitted, e.g. filters
    • F21V9/14—Elements for modifying spectral properties, polarisation or intensity of the light emitted, e.g. filters for producing polarised light
    • 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
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/0001—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems
    • G02B6/0011—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings specially adapted for lighting devices or systems the light guides being planar or of plate-like form
    • G02B6/0033—Means for improving the coupling-out of light from the light guide
    • G02B6/0056—Means for improving the coupling-out of light from the light guide for producing polarisation effects, e.g. by a surface with polarizing properties or by an additional polarizing elements
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices
    • G02F1/13362—Illuminating devices providing polarized light, e.g. by converting a polarisation component into another one
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/133528—Polarisers
    • G02F1/133536—Reflective polarizers
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/133528—Polarisers
    • G02F1/13355—Polarising beam splitters [PBS]

Definitions

  • the present invention relates generally to liquid crystal displays (LCD's) used in such applications as computer displays, calculators, electronic watches and the like, and particularly to apparatus for increasing the brightness of the images displayed by backlit LCD's without increasing the amount of power used by the backlight.
  • LCD's liquid crystal displays
  • Backlit LCD's may be used in applications which require moderately low power consumption, but in which the available ambient light may not be sufficient to enable viewing of the LCD.
  • LCD computer monitors are typically backlit.
  • a backlit LCD often includes a light pipe or thin transparent sheet of material extending across the back surface of the LCD.
  • a light source such as a fluorescent lamp, is positioned adjacent an edge of the light pipe. Light is piped through the transparent sheet and evenly distributed across the pipe surface to illuminate the LCD.
  • a linear dichroic polarizer disposed between the LCD and the light pipe filters the randomly polarized light, transmitting only light polarized parallel to the transmission axis of the polarizer.
  • the light emerging from the light pipe has a random polarization; that is, there is light with all possible polarization axes.
  • the linear dichroic polarizer transmits the portion of the light having a polarization parallel to the transmission axis of the polarizer.
  • a second linear dichroic polarizer extends across the front of the LCD.
  • the two polarizers which may have different orientations, cooperate to maximize the transmission difference between selected and unselected areas of the LCD's.
  • a well known problem with backlit LCD's is that the LCD may not be clearly legible under all environmental conditions.
  • the ambient light in some environments may be particularly bright, reducing the distinctiveness of the selected areas of the LCD.
  • a computer monitor may be difficult to read when facing a window.
  • a portable laptop computer particularly those with color displays
  • a major portion of the energy supplied by the battery is used to backlight the back side of the display.
  • sufficiently illuminating the display substantially reduces the usable life of the battery between recharges .
  • An LCD which is not bright enough interferes with an operator' s ability to utilize the application incorporating the LCD since the displayed images are not clearly legible.
  • a prismatic film is positioned between the light pipe and the back surface of the LCD to increase the brightness of the light emitted by the light pipe.
  • the prismatic film reflects light, by Total Internal Reflection (TIR), incident at angles which are within a specific range normal to the film plane and refracts light incident at angles outside of that range.
  • TIR Total Internal Reflection
  • a small percentage of light emitted by the light pipe is also reflected at the air/film surface interfaces.
  • the light reflected back towards the light pipe is scattered off its rear white reflector and is redirected towards the prismatic film.
  • the light is then either refracted through the film or reflected back towards the light pipe, depending upon the angle of incidence to the prismatic film of the particular ray.
  • Using the prismatic film to recycle the light emitted by the light pipe may increase the usable light intensity by 50% or more.
  • the images displayed on a backlit LCD having a prismatic layer between the LCD and the light pipe are somewhat brighter than those on a standard backlit LCD.
  • a problem with these backlit LCD's is that even with increased brightness, in some applications the displayed images may not be sufficiently clear and distinct.
  • the backlighting assembly is not efficient, since approximately 50% of the light is absorbed by the linear dichroic polarizer. Much of the light intensity provided by the combined light pipe and prismatic layer is still lost.
  • a primary object of the present invention is to provide a backlit LCD assembly which more efficiently uses the available light to increase the brightness of the displayed images.
  • Another object of the present invention is to provide a backlighting assembly for an LCD which substantially increases the brightness of images displayed on the LCD.
  • a further object of the present invention is to provide a backlit LCD assembly in which the displayed images are clear and legible in most environmental conditions.
  • a more general object of the present invention is to provide a backlit LCD assembly which may be economically manufactured.
  • the present invention is an LCD assembly with a backlighting apparatus which substantially increases the brightness of the displayed images.
  • the LCD assembly includes an LCD and a light source spaced from the rear surface of the LCD.
  • a linear polarizing layer extends across the rear surface of the LCD. Light polarized parallel to the polarization axis is transmitted by the linear polarizing layer.
  • a brightness increasing layer disposed between the polarizing layer and the light source has a preferred polarization axis in that the transmitted output has more light polarized in one direction (the preferred polarization) than another.
  • the brightness enhancing layer and the linear polarizing layer are oriented with the preferred polarization axis of the brightness increasing layer and the transmission axis of the polarizing layer aligned, providing for maximum light transmission and increasing the display brightness of the LCD.
  • the present invention also provides a method for enhancing the brightness of an LCD which includes the steps of providing an LCD, positioning a linear polarizing layer proximate the rear surface of the LCD and illuminating the LCD with a light source spaced from the linear polarizing layer.
  • a prismatic film is positioned between the light source and the polarizing layer. The prismatic film produces an output that is partially polarized, with more light polarized in one direction than another, such that the film has a preferred polarization axis.
  • the film is oriented with the preferred polarization axis substantially aligned with the transmission axis of the polarizing layer.
  • Figure 1 is an end view of an LCD assembly in accordance with the present invention.
  • Figure 1A is an enlarged fragmentary view of the area within the dashed line 1A in Figure 1.
  • Figure IB is an enlarged fragmentary view of the area within the dashed line IB in Figure 1.
  • Figure 2 is an enlarged top view of the prismatic film and linear dichroic polarizer of the LCD assembly of Figure 1.
  • Figure 3 is a table showing the light transmission and gain for various prismatic materials.
  • FIG. 4 is a cross sectional view of another embodiment of an LCD assembly in accordance with the present invention.
  • the assembly 10 generally includes a backlit LCD 12 which is illuminated by means of a light pipe 14.
  • the light pipe 14 is provided by a thin sheet of transparent material of substantially the same size as the LCD.
  • a light source such as a small diameter cold cathode fluorescent lamp 16 extends along an edge of the transparent sheet and provides the light for illuminating the display 12. Light travels from the light source into the light pipe 14, which transmits the light from the source 16 by Total Internal Reflection (TIR), with the light being internally reflected along the length of the pipe.
  • TIR Total Internal Reflection
  • a plurality of diffuse dots 18 of low loss white pigment are imprinted on a surface of the light pipe to produce a substantially Lambertian distribution of light.
  • the pigment is applied to the lower surface of the light pipe; however, the dots may also be provided on the upper surface.
  • Some of the light striking one of the diffuse dots 18 will exit the light pipe and illuminate the LCD .
  • the light leaving the light pipe 14 has an essentially random polarization; that is, the polarization axes of the rays of light leaving the light pipe are oriented in all directions. As light exits the light pipe, the intensity of the remaining light is reduced.
  • the density of the diffuse dots increases in relation to the distance separating the dot 18 from the light source 16 to compensate for the reduction in light intensity.
  • a reflector 20 is provided below the light pipe 14 to reflect light emitted from the bottom surface of the light pipe towards the LCD 12 so that substantially all of the light released from the light pipe is directed towards the LCD.
  • An air space 22 separates the reflector 20 from the lower surface of the light pipe since the reflector is not laminated or optically coupled to the light pipe 14. If laminated to the light pipe, the reflector would extract the internally reflected light from the light pipe.
  • the reflector 20 is preferably a non-specular or diffuse reflector to provide the reflected light with a substantially random polarization and direction.
  • a specular-type reflector 24 may be substituted for the non-specular reflector 20 as is shown in Figure 4. Polarized light reflected by the specular-type reflector 24 is generally not substantially depolarized.
  • a diffusing layer 25 is positioned above the light pipe 14 to ensure that the provided light has both random polarization and direction. A diffusing layer may also be used with a non-specular reflector to conceal the diffuse dots 18.
  • a prismatic film 28 is disposed between the LCD 12 and the light pipe 14 for enhancing the brightness of the images displayed on the LCD. Since the prismatic film is not laminated or optically coupled to either the LCD or the light pipe 14, air spaces 27 and 29 separate the prismatic film 28 from the light pipe and the LCD. The air spaces preserve the optical characteristics of light entering and leaving the film, preventing light from escaping in unwanted directions.
  • the film 28 includes a faceted surface 30 facing the back of the LCD and a substantially smooth or glossy surface 32 opposite the light pipe 14. Light emitted by the light pipe assembly is refracted by the smooth surface 32 and intersects faceted surface 30.
  • the faceted surface is formed with a plurality of grooves 33 defined by facets 34 of adjacent prisms 36.
  • the facets 34 of each prism 36 are separated by a prism angle .
  • a smooth surface 32 is preferred over a rough or scattering back surface which would increase the angles of light within the film and spread the output further, thereby reducing the display brightness.
  • the prismatic film is constructed of a material having an index of refraction substantially greater than 1.0 and preferably greater than 1.41, providing for total internal reflection of light intersecting the faceted surface at an angle ( ⁇ ) greater than the critical angle (0 C ) for the selected material.
  • a portion of light generally designated by rays 40 is reflected back towards the light pipe 14.
  • the light ray 40 intersects one of the facets 34 at an angle ⁇ > ⁇ . and is internally reflected.
  • the reflected ray 40 intersects an adjacent facet 34 at an angle ⁇ > ⁇ ., where it is totally reflected towards the light pipe 14.
  • the reflected light passes through the light pipe and is scattered by the non-specular reflector 20, rerandomizing both the polarization and direction.
  • the scattered light indicated generally at 41, travels through the light pipe 14 and re-enters the prismatic film 28. If any rays of the scattered light 41 intersect the facets 34 at an angle ⁇ > ⁇ c , the rays will again be totally internally reflected and redirected towards the reflector 20. Although not shown, some of the light will also be reflected by the air/film interface at the smooth surface 32 of the prismatic film.
  • a portion of the light entering the prismatic film intersects one of the facets 34 of the faceted surface at an angle ⁇ ⁇ ⁇ . as is shown in Figures 1 and IB.
  • a portion of the light designated by ray 42 is refracted towards the LCD 12, while the remainder of the light is directed through the prism 36 towards another facet 34.
  • Light intersecting the facet 34 is split, with a portion being reflected towards the light pipe and the remainder passing into the prismatic film.
  • the light reentering the film will either be reflected or refracted, depending upon the angle at which the light intersects the interior of the faceted surface 30.
  • a ray striking the smooth surface 32 at an angle is also refracted, as is shown by ray 42 in Figure 1, with a portion being directed towards the faceted surface and the remainder being reflected towards the light pipe.
  • the faceted surface 30 tends to normalize the direction of the refracted light relative to the prismatic film 28.
  • Light having a substantially normal orientation preferably within the range of ⁇ 30° horizontally and ⁇ 15° vertically from a normal axis, is an optimum range for viewing the LCD.
  • the refracted light is concentrated into a zone which extends outward from an axis normal to the film to ensure that a major portion of the transmitted light falls within an optimum range.
  • the area over which the concentrated zone extends depends upon the index of refraction of the film and the prism angle .
  • the film is a polycarbonate material having a nominal index of refraction of 1.586 and the prism angle is 90° .
  • the zone into which the light is concentrated is within the range of approximately ⁇ 55° in a direction parallel to the grooves 33 and approximately ⁇ 35° in a direction perpendicular to the grooves.
  • Increasing the prism angle a increases the area of the zone of concentration, while a smaller prism angle concentrates the light into a narrower zone.
  • a prism angle of 90° is preferred as the total reflectance of light from a Lambertian source is maximized at this angle, providing more light to be recycled, thereby enhancing brightness. With angles smaller than 90°, the potential gain is reduced and more light escapes at uncontrolled angles.
  • the electric vector of polarized light may be resolved into components of polarization parallel to and perpendicular to the plane of incidence (i.e. the plane defined by the incident ray, such as the light designated by rays 40 and 42, striking the facet 34 and an axis normal to the facet 34).
  • a higher percentage of light reflected by the prismatic film 28 has a polarization perpendicular to the plane of incidence, resulting in more of the transmitted light having a polarization axis parallel to the plane of incidence.
  • the output transmitted by the film is partially polarized, with the polarization axis of peak intensity being parallel to the plane of incidence.
  • the transmission of a partially polarized output provides the prismatic film with a preferred polarization axis 46 which is parallel to the polarization axis of peak intensity, or in other words parallel to plane of incidence.
  • the polarization axis of peak intensity, and therefore the preferred polarization axis 46 of the film is perpendicular to the grooves 33.
  • Light entering the prismatic film at an angle may be slightly polarized due to the exit angle from the previous layer.
  • a very diffuse translucent (low absorbance) sheet is used for the diffusing layer, light exiting the diffuse sheet at 30.25° from a normal axis has been found to have a ratio of light polarized parallel to the plane of incidence to light polarized perpendicular to the plane of incidence of 1.03.
  • thermoplastic polymeric film materials include, but are not limited to, acrylics, polystyrenes and thermoplastic polyesters.
  • the prismatic film may also be a composite construction of a base film with the microstructured prisms formed in a UV-cured second layer.
  • the facets 34 formed on the prismatic film 28 in the preferred embodiment are of equal size, providing 90° isosceles prisms.
  • the grooves 33 have a width of .002 inch extending between the peaks of the adjacent prisms 36.
  • the 90° prisms and the high index of refraction maximize the polarization effect of the film 28.
  • Figure 3 shows theoretical light transmission and gain calculated for prismatic films having selected prism angles a (called the "included angle" in Figure 3) and indices of refraction, assuming a "perfect" backlight having no losses and ignoring the polarization effect.
  • the LCD assembly 10 further includes a polarizing layer, such as linear dichroic polarizer 50, extending across the back surface of the LCD.
  • the linear dichroic polarizer 50 has a transmission axis 52 such that light of one polarization, that polarized parallel to the axis 52, is transmitted and used to illuminate the LCD. Light polarized perpendicular to the transmission axis 52 is blocked or substantially absorbed by the polarizer.
  • a second polarizing layer or linear dichroic polarizer 54 extends across the front surface of the LCD 12. The polarizers 50 and 54 cooperate to provide a maximum difference in transmission between the selected and unselected areas of the LCD 12.
  • the polarizer 50 and the film 28 are oriented relative to one another with the preferred polarization axis 46 of the film substantially aligned with the transmission axis 52 of the polarizer.
  • the film 28 is positioned with the grooves 33 extending in a direction substantially orthogonal to the transmission axis of the polarizer.
  • This configuration maximizes the amount of light transmitted by the film 28 which is available for illuminating the display.
  • the axes 46 and 52 are not completely aligned, the amount of polarized light transmitted will be reduced by a factor proportional to cos 2 0, where ⁇ represents the angle between the polarization axis 52 and the maximum intensity axis 46. For example, with a 30° misalignment, the amount of polarized light transmitted will be reduced by 25 % of the polarized light transmitted with the axes completely aligned.
  • the light entering the prismatic film may have a slight polarization when a diffuser is positioned between the light pipe 14 and the film 28, for example a ratio of 1.03 at an angle of 30.25 ° to a normal axis.
  • the brightness was found to be about 17% and 24% greater, respectively, with the axes aligned than when the axes are orthogonal.
  • the preferred polarization axis 46 with the transmission axis 52 of the polarizer, the brightness of the LCD is substantially increased.
  • Aligning the maximum intensity axis and the polarization axis of the polarizer produces a theoretical gain of approximately 100% over the brightness of an LCD assembly without the prismatic film, and a gain of 11 % over an assembly having a prismatic film and diffuser where the maximum intensity axis is skewed 90° relative to the polarization axis of the polarizer.
  • the output produced by the film is concentrated into a limited zone surrounding the optimum viewing range.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Nonlinear Science (AREA)
  • Mathematical Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Optical Elements Other Than Lenses (AREA)

Abstract

L'invention concerne un ensemble et un procédé d'affichage à cristaux liquides à luminosité améliorée. L'ensemble comprend un affichage à cristaux liquides, une couche polarisante linéaire s'étendant sur la surface arrière de l'affichage et une source d'éclairage espacée de la couche polarisante. Une couche améliorant la luminosité placée entre la couche polarisante et la source d'éclairage possède un axe de polarisation préféré, transmettant ainsi plus de lumière polarisée dans un sens que dans l'autre. La couche augmentant la luminosité est orientée avec l'axe de polarisation préféré, sensiblement aligné sur l'axe de transmission de la couche polarisante. Le procédé consiste à produire un affichage à cristaux liquides, à positionner une couche polarisante linéaire à côté de la surface arrière de l'affichage et à éclairer l'affichage au moyen d'une source d'éclairage espacée de la couche polarisante. Un film prismatique possèdant un axe de polarisation préféré et transmettant une sortie partiellement polarisée, est positionné entre la couche polarisante et la source d'éclairage. Le procédé consiste également à orienter le film prismatique avec l'axe de polarisation préféré, sensiblement aligné sur l'axe de transmission de la couche polarisante.
PCT/US1994/005936 1993-06-08 1994-05-26 Affichage a cristaux liquides a luminosite amelioree WO1994029765A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US7369993A 1993-06-08 1993-06-08
US08/073,699 1993-06-08

Publications (1)

Publication Number Publication Date
WO1994029765A1 true WO1994029765A1 (fr) 1994-12-22

Family

ID=22115249

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1994/005936 WO1994029765A1 (fr) 1993-06-08 1994-05-26 Affichage a cristaux liquides a luminosite amelioree

Country Status (1)

Country Link
WO (1) WO1994029765A1 (fr)

Cited By (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1995017699A1 (fr) * 1993-12-21 1995-06-29 Minnesota Mining And Manufacturing Company Affichage a polariseur reflectif
EP0762183A4 (fr) * 1995-03-08 1997-07-23 Nitto Jushi Kogyo Kabushiki Ka Source plate de lumiere et affichage a cristaux liquides
WO1997032226A1 (fr) * 1996-02-29 1997-09-04 Minnesota Mining And Manufacturing Company Film a brillance augmentee
US5686979A (en) * 1995-06-26 1997-11-11 Minnesota Mining And Manufacturing Company Optical panel capable of switching between reflective and transmissive states
US5783120A (en) * 1996-02-29 1998-07-21 Minnesota Mining And Manufacturing Company Method for making an optical film
US5825543A (en) * 1996-02-29 1998-10-20 Minnesota Mining And Manufacturing Company Diffusely reflecting polarizing element including a first birefringent phase and a second phase
US5825542A (en) * 1995-06-26 1998-10-20 Minnesota Mining And Manufacturing Company Diffusely reflecting multilayer polarizers and mirrors
US5831375A (en) * 1995-08-11 1998-11-03 Minnesota Mining And Manufacturing Company Electroluminescent lamp using multilayer optical film
US5867316A (en) * 1996-02-29 1999-02-02 Minnesota Mining And Manufacturing Company Multilayer film having a continuous and disperse phase
US6005713A (en) * 1998-08-21 1999-12-21 3M Innovative Properties Company Multilayer polarizer having a continuous and disperse phase
EP1055944A1 (fr) * 1999-05-24 2000-11-29 Nitto Denko Corporation Element de polarisation et element optique
US6160663A (en) * 1998-10-01 2000-12-12 3M Innovative Properties Company Film confined to a frame having relative anisotropic expansion characteristics
USRE37377E1 (en) 1992-10-09 2001-09-18 Asahi Glass Company, Ltd. LCD device including an illumination device having a polarized light separating sheet between a light guide and the display
WO2001071248A1 (fr) * 2000-03-16 2001-09-27 3M Innovative Properties Company Guides optiques adaptes aux affichages lumineux
US6888675B2 (en) 1995-03-10 2005-05-03 3M Innovative Properties Company Transflective displays with reflective polarizing transflector
US6893135B2 (en) 2000-03-16 2005-05-17 3M Innovative Properties Company Light guides suitable for illuminated displays
US6903788B2 (en) 2001-07-05 2005-06-07 Nitto Denko Corporation Optical film and a liquid crystal display using the same
EP1586813A1 (fr) 2004-04-16 2005-10-19 3M Innovative Properties Company Boíte à lumière
WO2005119353A1 (fr) * 2004-05-28 2005-12-15 Eastman Kodak Company Film reflechissant a diffusion pour eclairage de fond d’affichage a cristaux liquides
US6987612B2 (en) 1996-02-29 2006-01-17 3M Innovative Properties Company Optical film with co-continuous phases
US7038745B2 (en) 1993-12-21 2006-05-02 3M Innovative Properties Company Brightness enhancing reflective polarizer
US7083847B2 (en) 1993-12-21 2006-08-01 3M Innovative Properties Company Optical film
US7321464B2 (en) 1993-12-21 2008-01-22 3M Innovative Properties Company Electroluminescent light source and display incorporating same
JP2019040195A (ja) * 2004-11-12 2019-03-14 東レ株式会社 バックライトの反射板用白色フィルムおよびそれを用いたバックライト

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3349238A (en) * 1964-12-31 1967-10-24 Smithcraft Corp Glare-free office lighting device and the like
JPH04318534A (ja) * 1991-04-17 1992-11-10 Seiko Epson Corp 偏光分離手段、光源装置及びそれを用いた投写型表示装置
EP0531939A1 (fr) * 1991-09-09 1993-03-17 Enplas Corporation Surface lumineuse
JPH0618873A (ja) * 1992-07-01 1994-01-28 Fujitsu Ltd 液晶表示装置
EP0597261A1 (fr) * 1992-10-09 1994-05-18 Asahi Glass Company Ltd. Dispositif d'éclairage et dispositif d'affichage à cristal liquide

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3349238A (en) * 1964-12-31 1967-10-24 Smithcraft Corp Glare-free office lighting device and the like
JPH04318534A (ja) * 1991-04-17 1992-11-10 Seiko Epson Corp 偏光分離手段、光源装置及びそれを用いた投写型表示装置
EP0531939A1 (fr) * 1991-09-09 1993-03-17 Enplas Corporation Surface lumineuse
JPH0618873A (ja) * 1992-07-01 1994-01-28 Fujitsu Ltd 液晶表示装置
EP0597261A1 (fr) * 1992-10-09 1994-05-18 Asahi Glass Company Ltd. Dispositif d'éclairage et dispositif d'affichage à cristal liquide

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
"polarized backlight for liquid crystal", IBM TECHNICAL DISCLOSURE BULLETIN, vol. 33, no. 1B, June 1990 (1990-06-01), NEW YORK US, pages 143 - 144 *
M.F.WEBER: "RETROREFLECTING SHEET POLARIZER", SID INTERNATIONAL SYMPOSIUM .DIGEST OF TECHNICAL PAPER, vol. 23, 1992, USA, pages 427 - 429 *
PATENT ABSTRACTS OF JAPAN vol. 17, no. 147 (P - 1508) *
PATENT ABSTRACTS OF JAPAN vol. 18, no. 223 (P - 1729) *

Cited By (36)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
USRE38305E1 (en) 1992-10-09 2003-11-11 Asahi Glass Company Ltd. LCD device including an illumination device having a polarized light separating sheet between a light guide and the display
USRE37377E1 (en) 1992-10-09 2001-09-18 Asahi Glass Company, Ltd. LCD device including an illumination device having a polarized light separating sheet between a light guide and the display
WO1995017699A1 (fr) * 1993-12-21 1995-06-29 Minnesota Mining And Manufacturing Company Affichage a polariseur reflectif
US7423708B2 (en) 1993-12-21 2008-09-09 3M Innovative Properties Company Display having a reflective polarizer
US7321464B2 (en) 1993-12-21 2008-01-22 3M Innovative Properties Company Electroluminescent light source and display incorporating same
US7297393B2 (en) 1993-12-21 2007-11-20 3M Innovative Properties Company Optical film
US7083847B2 (en) 1993-12-21 2006-08-01 3M Innovative Properties Company Optical film
US7038745B2 (en) 1993-12-21 2006-05-02 3M Innovative Properties Company Brightness enhancing reflective polarizer
US5966192A (en) * 1995-03-08 1999-10-12 Nitto Jushi Kogyo Kabushiki Kaisha Surface light source device and a liquid crystal display
EP0762183A4 (fr) * 1995-03-08 1997-07-23 Nitto Jushi Kogyo Kabushiki Ka Source plate de lumiere et affichage a cristaux liquides
US6888675B2 (en) 1995-03-10 2005-05-03 3M Innovative Properties Company Transflective displays with reflective polarizing transflector
US5686979A (en) * 1995-06-26 1997-11-11 Minnesota Mining And Manufacturing Company Optical panel capable of switching between reflective and transmissive states
US5825542A (en) * 1995-06-26 1998-10-20 Minnesota Mining And Manufacturing Company Diffusely reflecting multilayer polarizers and mirrors
US5831375A (en) * 1995-08-11 1998-11-03 Minnesota Mining And Manufacturing Company Electroluminescent lamp using multilayer optical film
US6141149A (en) * 1996-02-29 2000-10-31 3M Innovative Properties Company Multilayer film having a continuous and disperse phase
US5867316A (en) * 1996-02-29 1999-02-02 Minnesota Mining And Manufacturing Company Multilayer film having a continuous and disperse phase
US6987612B2 (en) 1996-02-29 2006-01-17 3M Innovative Properties Company Optical film with co-continuous phases
WO1997032226A1 (fr) * 1996-02-29 1997-09-04 Minnesota Mining And Manufacturing Company Film a brillance augmentee
US6031665A (en) * 1996-02-29 2000-02-29 3M Innovative Properties Company Method of forming a multilayer film having a continuous and disperse phase
US6760157B1 (en) 1996-02-29 2004-07-06 3M Innovative Properties Company Brightness enhancement film
US5991077A (en) * 1996-02-29 1999-11-23 3M Innovative Properties Company Multilayer polarizer having a continuous and disperse phase
US5783120A (en) * 1996-02-29 1998-07-21 Minnesota Mining And Manufacturing Company Method for making an optical film
US7057816B1 (en) 1996-02-29 2006-06-06 3M Innovative Properties Company Optical film with co-continuous phases
US5825543A (en) * 1996-02-29 1998-10-20 Minnesota Mining And Manufacturing Company Diffusely reflecting polarizing element including a first birefringent phase and a second phase
US6999233B2 (en) 1996-02-29 2006-02-14 3M Innovative Properties Company Optical film with co-continuous phases
US6005713A (en) * 1998-08-21 1999-12-21 3M Innovative Properties Company Multilayer polarizer having a continuous and disperse phase
US6160663A (en) * 1998-10-01 2000-12-12 3M Innovative Properties Company Film confined to a frame having relative anisotropic expansion characteristics
EP1055944A1 (fr) * 1999-05-24 2000-11-29 Nitto Denko Corporation Element de polarisation et element optique
KR100773796B1 (ko) * 2000-03-16 2007-11-07 쓰리엠 이노베이티브 프로퍼티즈 캄파니 조명 디스플레이에 적합한 광 가이드
US6893135B2 (en) 2000-03-16 2005-05-17 3M Innovative Properties Company Light guides suitable for illuminated displays
WO2001071248A1 (fr) * 2000-03-16 2001-09-27 3M Innovative Properties Company Guides optiques adaptes aux affichages lumineux
US6903788B2 (en) 2001-07-05 2005-06-07 Nitto Denko Corporation Optical film and a liquid crystal display using the same
WO2005106321A1 (fr) 2004-04-16 2005-11-10 3M Innovative Properties Company Caisson lumineux
EP1586813A1 (fr) 2004-04-16 2005-10-19 3M Innovative Properties Company Boíte à lumière
WO2005119353A1 (fr) * 2004-05-28 2005-12-15 Eastman Kodak Company Film reflechissant a diffusion pour eclairage de fond d’affichage a cristaux liquides
JP2019040195A (ja) * 2004-11-12 2019-03-14 東レ株式会社 バックライトの反射板用白色フィルムおよびそれを用いたバックライト

Similar Documents

Publication Publication Date Title
WO1994029765A1 (fr) Affichage a cristaux liquides a luminosite amelioree
EP1173783B1 (fr) Dispositifs optiques utilisant des materiaux polarisants et reflechissants
KR101277872B1 (ko) 다기능 향상 필름
US7072544B2 (en) Polarized light-emitting waveguide plate
KR101336397B1 (ko) 색상 혼합 조명 유닛 및 이를 이용한 광학 시스템
US6590625B1 (en) Liquid-crystal display device
US7385659B2 (en) Structured transflectors for enhanced ambient and backlight operation of transmissive liquid crystal displays
JP4487629B2 (ja) 面照明装置及びそれを用いた液晶表示装置
US7384173B2 (en) Brightness enhancement article
US6975455B1 (en) Transflective layer for displays
US20080266904A1 (en) Optical film having a surface with rounded structures
US20070153543A1 (en) Flat panel displays with primary viewing envelopes away from displyay panel normal
KR101528910B1 (ko) 광학시트 및 이를 갖는 액정 표시장치
US20040155995A1 (en) Light guide plate with embossments and backlight system using the same
US20050276073A1 (en) Diffusive reflector films for enhanced liquid crystal display efficiency
JP2001133773A (ja) 液晶表示装置及び導光板
JP3604413B2 (ja) 直視型液晶表示装置
JP2002323607A (ja) 光制御シート、面光源装置及び画像表示装置
JPH06250169A (ja) 照明装置および液晶表示装置
JPH10319393A (ja) 液晶表示装置
JP2008210560A (ja) ディスプレイ用光学シート及びこれを用いたバックライト・ユニット並びに表示装置
JPH05241147A (ja) 平面光源装置
US20050271348A1 (en) Prism sheet for a backlight module
JP2003177401A (ja) 表示装置及びそれを用いた電子機器
JP2008134563A (ja) 光学シートとそれを用いたバックライト・ユニットおよびディスプレイ

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): CA CN JP KR

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): AT BE CH DE DK ES FR GB GR IE IT LU MC NL PT SE

121 Ep: the epo has been informed by wipo that ep was designated in this application
DFPE Request for preliminary examination filed prior to expiration of 19th month from priority date (pct application filed before 20040101)
122 Ep: pct application non-entry in european phase
NENP Non-entry into the national phase

Ref country code: CA