US007.405779B2
`
`(12) United States Patent
`Sanelle et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 7405,779 B2
`Jul. 29, 2008
`
`(54) SUPER BRIGHT LOW REFLECTANCE
`LIQUID CRYSTAL DISPLAY
`(75) Inventors: Joseph J. Sanelle, Westboro, MA (US);
`Diggy R. Breiling, Beaverton, OR (US);
`Daniel R. Doyle, Medway, MA (US)
`(73) Assignee: White Electronic Designs Corp.,
`Phoenix, AZ (US)
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 0 days.
`(21) Appl. No.: 11/209,102
`(22) Filed:
`Aug. 22, 2005
`
`(*) Notice:
`
`(65)
`
`Prior Publication Data
`US 2006/OOO18OO A1
`Jan. 5, 2006
`
`Related U.S. Application Data
`(63) Continuation of application No. 09/772,197, filed on
`Jan. 29, 2001, now Pat. No. 6,933,991, which is a
`continuation-in-part of application No. 09/235.584,
`filed on Jan. 22, 1999, now Pat. No. 6,181,394.
`
`(51) Int. Cl.
`(2006.01)
`GO2F I/335
`(2006.01)
`GO2F I/33
`(52) U.S. Cl. ............................. 349/96: 349/12: 349/23;
`34.9/137
`(58) Field of Classification Search ................. 34.9/137,
`349/96, 12, 23
`See application file for complete search history.
`References Cited
`
`(56)
`
`U.S. PATENT DOCUMENTS
`
`9, 1992 Terada
`5,148.299 A
`6, 1998 Inou ........................... 345,104
`5,774,107 A
`5,818,559 A 10, 1998 Yoshida
`6,281,952 B1* 8/2001 Okamoto et al. .............. 349/12
`6,369,865 B2
`4/2002 Hinata ......................... 349/12
`FOREIGN PATENT DOCUMENTS
`O SO2 364 A1
`9, 1992
`
`EP
`
`JP
`JP
`E.
`JP
`WO
`WO
`
`2, 1991
`A-3-16128
`2, 1992
`A-4-13981
`g
`Age.
`7, 1993
`A-5-173707
`4f1993
`WO93,08489 A1
`T 2000
`WOOOf 43832 A1
`OTHER PUBLICATIONS
`Bahadur, Liquid Crystals 1990, World Scientific, vol. 1, pp. 173
`193*
`* cited by examiner
`Primary Examiner David C. Nelms
`Assistant Examiner David Y Chung
`(74) Attorney, Agent, or Firm—Kriegsman & Kriegsman
`
`ABSTRACT
`(57)
`A liquid crystal display (LCD) exhibiting enhanced optical
`viewing performance. In a preferred embodiment, the LCD
`comprises a liquid crystal display panel, the liquid crystal
`display panel comprising a pair of transparent Substrates,
`liquid crystal material sandwiched between the transparent
`Substrates and transparent electrodes positioned between the
`liquid crystal material and the transparent Substrates. The
`LCD also comprises a rear polarizer assembly comprising a
`compensation film, a polarizer mounted on the rear Surface of
`the compensation film, and a first index-matched, pressure
`sensitive adhesive (PSA) mounted on the front surface of the
`compensation film, the PSA being adhered to the rear surface
`of the LCD panel. The LCD also comprises a front polarizer
`assembly, the front polarizer assembly comprising a front
`polarizer, a compensation film mounted on the rear Surface of
`the front polarizer and an index-matched PSA mounted on the
`front surface of the front polarizer. The front polarizer is
`crossed relative to the rear polarizer. The front polarizer
`assembly may be adhered to the front of the LCD panel with
`a second index-matched, optical bonding material or may be
`spaced therefrom by an air gap. A transparent cover is
`mounted on the second index-matched PSA. The transparent
`cover is preferably a plastic plate. The plastic plate may be
`textured to reduce glare or may have an anti-reflection coating
`or an anti-reflection film applied to the front surface thereof.
`Instead of a plastic plate, the transparent cover may be a glass
`plate or a touch panel.
`
`2 Claims, 4 Drawing Sheets
`
`11
`
`Ny
`39
`35 ZZZZZZZZZZZZZZZZZZAAAAA
`31S & 33
`13
`ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
`29XX
`
`
`
`aaZZZZZZYZa 2 1
`
`
`
`19S & 25
`
`23 N
`15
`AAAAAZZZZZZZYZZZZZZZZZZZZZAA
`
`%-41
`
`Page 1 of 10
`
`Tianma Exhibit 1013
`
`

`

`U.S. Patent
`
`Jul. 29, 2008
`
`Sheet 1 of 4
`
`US 7405,779 B2
`
`11
`
`35
`
`NSNSNSNSNSNS 39
`ZZZZZZZZZZZZZZZZAAAAZZZ
`AAAAAAAAAAAYAAAAAAAAYAAAZZY/AAAAAAAAAAYAAAAAA
`37
`31S S&133
`13
`ZZZZZZZZZZZZZZZZZZAZZZZZZZZZZZZZZ
`29&
`
`
`
`
`
`ZZZZZZZAZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZA
`
`2 1
`
`19S &125
`
`23 N
`ZAZ7777777.777777/7ZZZZZZZZZZZMA
`1 5
`
`%-41
`
`FIG. I.
`
`17
`
`NYYYYYYYYYYYYYYY
`
`LZZZZZZZZZZZZZZZZZZ
`
`14-1
`16-1
`
`12
`
`
`
`
`
`
`
`€1.
`
`
`
`FIG 2
`
`Page 2 of 10
`
`

`

`U.S. Patent
`
`Jul. 29, 2008
`
`Sheet 2 of 4
`
`US 7405,779 B2
`
`151
`Ny
`39
`777,77777/777/7ZZZZ
`a S&133
`13 4.
`29XX
`
`
`
`
`
`
`
`
`
`35
`
`
`
`
`
`8-N-
`NXXXXANAX7&XAXAXNx MXXXMAN & 25
`23 N
`Z77AAAAAAAAAZZZZZZZZZZZZZZYZZZZZZZ
`
`%-41
`
`FIG 3
`
`1. 71
`ZZZZZZZZZZZZZZZZZZ-75
`N. 77
`
`A A A. Al-A-A. A. A ...A-A-A All A-A A. AAA
`
`FIG. 4
`
`
`
`FIG. 5
`
`Page 3 of 10
`
`

`

`U.S. Patent
`
`Jul. 29, 2008
`
`Sheet 3 of 4
`
`US 7405,779 B2
`
`101
`
`Ny
`131
`ZZZZZZZZZZZZZZZZZZZZZZZZZZZ
`121
`777,7777,77777AAAAZZZZZYAYAZZZZYZZZZZZZZZYZZZZZZZ SS KXXXXXXXXXXXXXXXXXXXXXXXXXX)
`119
`XXXXXXXX
`
`
`
`125
`115
`
`
`
`ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZYZ
`109 NNNNNNNNNNNNNNNNNNNNNN
`
`11
`
`%-141
`
`FIG. 6
`
`201
`
`
`
`NVVVNV Ny
`205
`NNNNNNNNNNNNNNNNNN
`2O7
`N
`ZZZZZZZZZZZZZZZZZZZZZZZZZZZ
`121
`ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
`NNNN
`XXXX XXXX XXXX XXXXXX XXX XXXXXX
`19
`KXXXXXXXXXXXXXXXXXXXXXXXXXXX
`XXXXXXXXXXXXXXXXXXXXXXXXXXX
`105
`111
`777A7777AAZZZZZZZZZZZZZZZZY
`N
`
`203
`125
`115
`
`
`
`
`
`109
`
`%-141
`
`FIG. 7
`
`Page 4 of 10
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`

`

`U.S. Patent
`
`Jul. 29, 2008
`
`Sheet 4 of 4
`
`US 7405,779 B2
`
`301
`
`NNNNNNNNN- 131
`125 N77,777,777,777,777
`115
`SNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
`1. 303
`
`AZZZZZYZZZZZYZZZZZZZZZZZZZZZZZZZZZZZZZZZZYZ
`109 NNNNNNNNNNNNNNNNNNNN
`
`1 1
`
`W-141
`
`FIG. 8
`
`401
`
`403
`
`125
`115
`
`
`
`
`
`
`
`Ny
`131
`ZZAZAZAZ777/7777AAZZZZZZA
`121
`ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZYZZZZZZZZZZZ
`NNNN
`XXXXXXXXXXXXXXXXX XXXXXXXXXX
`119
`KXXXXXXXXXXXXXXXXXXXXXXXXXXX
`XXXXXXXXXXXXXXXXXX
`
`YZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ
`109 NNNNNNNNNNNNNNNNNNNNN
`
`
`
`111
`
`%-141
`
`FIG. 9
`
`Page 5 of 10
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`

`

`1.
`SUPER BRIGHT LOW REFLECTANCE
`LIQUID CRYSTAL DISPLAY
`
`US 7,405,779 B2
`
`CROSS-REFERENCE TO RELATED
`APPLICATIONS
`
`The present application is a continuation of U.S. patent
`application Ser. No. 09/772,197, inventors Sanelle et al., filed
`Jan. 29, 2001, now U.S. Pat. No. 6,933,911 which in turn is a
`continuation-in-part of U.S. patent application Ser. No.
`09/235,584, inventors Sanelle et al., filed Jan. 22, 1999, now
`U.S. Pat. No. 6,181,394, the disclosures of which are incor
`porated herein by reference.
`
`BACKGROUND OF THE INVENTION
`
`10
`
`15
`
`30
`
`35
`
`40
`
`The present invention relates generally to liquid crystal
`displays and more particularly to an improved liquid crystal
`display exhibiting enhanced optical viewing performance.
`Liquid crystal displays, which were first introduced in the
`1970s and have since been used in watches, clocks, pocket
`calculators, portable personal computers, navigational instru
`ments and the like, are electronically Switched displays that
`make use of changes in the reflective properties of liquid
`crystals present in an electric field. A typical liquid crystal
`25
`display comprises a liquid crystal display panel (also com
`monly referred to as a liquid crystal display cell), said panel
`comprising a thin film of liquid crystals sandwiched between
`a pair of transparent Substrates, each of the transparent Sub
`strates typically having a transparent electrically conductive
`coating applied to the liquid crystal side thereof, said trans
`parent coating functioning as an electrode. The liquid crystal
`display panel is typically positioned between a pair of glass
`(or other transparent) cover plates, the cover plates being
`sealed together around their respective edges. The cover
`plates may be assembled with spacers between them to main
`tain a constant separation distance. Two crossed axis polariz
`ers are positioned between the cover plates, one polarizer
`being adhered to the front of the liquid crystal display panel
`and the other polarizer being adhered to the rear of the liquid
`crystal display panel. When a Voltage is applied selectively
`across the electrodes, the liquid crystal molecules between
`them are rearranged or Switched in polarization so that light is
`either reflected or absorbed in the region bounded by the
`electrodes to form characters or graphics. Many liquid crystal
`displays include a backlight for night or dark viewing, and
`many liquid crystal displays include a layer of indium tin
`oxide or another suitable material positioned between the
`front polarizer and the front cover plate for use as an electro
`magnetic interference shield. Some liquid crystal displays
`intended for use in cold environments also include a layer of
`indium tin oxide or another Suitable material positioned
`between the rear polarizer and the rear cover plate and elec
`trically connected to a power Source for use as a heating
`element.
`55
`Some of the advantages of liquid crystal displays, as com
`pared to other digital displays, are their comparatively low
`Voltage and power requirements. Unfortunately, however,
`one of the principal disadvantages of liquid crystal displays is
`that, due to their low contrast and a “washed-out effect
`caused by back-reflected ambient light seen by a viewer, they
`cannot easily be read under high ambient light conditions,
`Such as when placed in direct Sunlight.
`One approach which has been taken to improve the viewing
`performance of liquid crystal displays, particularly when
`viewed under high ambient light conditions, has been to apply
`an anti-reflection coating to the front of the front cover plate.
`
`45
`
`50
`
`60
`
`65
`
`2
`Although Such an approach has provided some improvement
`to the viewing characteristics of liquid crystal displays by
`reducing the amount of back-reflected light seen by the
`viewer, further improvement is greatly needed.
`A few patents in the field of liquid crystal display technol
`ogy are described below.
`In U.S. Pat. No. 5,818,559, inventorYoshida, which issued
`Oct. 6, 1998, there is disclosed a liquid crystal display having
`different linear expansion coefficients among the materials of
`the display. More specifically, the liquid crystal display com
`prises a liquid crystal cell and a polarizing sheet stuck with an
`adhesive layer, said cell comprising a liquid crystal inter
`posed between a pair of resinous Substrates, at least one of
`which has a transparent electrode, and said polarizing sheet
`comprising a polarizing film interposed between a pair of
`resinous protective films, wherein difference in a linear
`expansion coefficient between the resin of the substrate fac
`ing the polarizing sheet and the resin of the protective film
`facing the liquid crystal cell is less than 0.5x10/°C.
`In U.S. Pat. No. 5,523,873, inventors Bradford, III et al.,
`which issued Jun. 4, 1996, and which is incorporated herein
`by reference, there is disclosed a liquid crystal display com
`prising first and second polarizers Sandwiching a liquid crys
`tal layer therebetween, electrode means for applying a Volt
`age across the liquid crystal layer, and a heater disposed
`adjacent (directly or otherwise) the first polarizer, the heater
`comprising a conductive layer having a Substantially planar
`flex circuit buss bar disposed thereon, the buss bar for deliv
`ering power to the conductive layer, thereby enabling the
`conductive layer to heat the liquid crystal display.
`In U.S. Pat. No. 3,869,196, inventor Kubota, which issued
`Mar. 4, 1975, and which is incorporated herein by reference,
`there is disclosed a liquid crystal display device wherein the
`thickness and the loss of light by reflection are said to be
`decreased by using one Surface from each of a polarizer and
`an analyzer for forming a cell in which the liquid crystal
`material is confined.
`Other patents of interest include U.S. Pat. No. 5,179,457,
`inventors Hirataka et al., which issued Jan. 12, 1993; U.S. Pat.
`No. 5,430,607, inventor Smith, issued Jul. 4, 1995: U.S. Pat.
`No. 5,570,214, inventors Abileah et al., which issued Oct. 29,
`1996; U.S. Pat. No. 5,594,568, inventors Abileah et al., which
`issued Jan. 14, 1997: U.S. Pat. No. 5,706,068, inventors
`Abileah et al., which issued Jan. 6, 1998; and U.S. Pat. No.
`5,739,881, inventors Xu et al., which issued Apr. 14, 1998, all
`of which are incorporated by reference.
`
`SUMMARY OF THE INVENTION
`
`It is an object of the present invention to provide a novel
`liquid crystal display.
`It is another object of the present invention to provide a
`liquid crystal display that ameliorates at least some of the
`problems discussed above in connection with existing liquid
`crystal displays.
`It is yet another object of the present invention to provide a
`liquid crystal display as described above that includes a novel
`optical filtering arrangement.
`The present invention is based, in part, on the innovative
`discovery that the amount of back-reflected light seen by a
`viewer of a liquid crystal display can be substantially reduced
`and, therefore, that the viewing characteristics of a liquid
`crystal display can be substantially improved by moving the
`front polarizer from its conventional location where it is
`adhered to the front surface of the liquid crystal display panel
`and is positioned rearwardly relative to the front cover plate to
`a new location where it is positioned in front of said front
`
`Page 6 of 10
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`

`

`3
`cover plate and is preferably adhered to the back surface of an
`additional cover plate itself positioned in front of said front
`cover plate.
`Therefore, according to one aspect of the invention, there is
`provided a liquid crystal display comprising (a) a first trans
`parent plate; (b) a second transparent plate; (c) a liquid crystal
`display panel positioned between said first and second trans
`parent plates, said liquid crystal display panel comprising a
`first transparent Substrate, a second transparent Substrate, liq
`uid crystal material positioned between said first and second
`transparent Substrates, a first transparent electrode positioned
`between said liquid crystal material and said first transparent
`Substrate, and a second transparent electrode positioned
`between said liquid crystal material and said second transpar
`ent Substrate; (d) a rear polarizer positioned between said
`liquid crystal display panel and said second transparent plate;
`and (e) a front polarizer positioned in front of said first trans
`parent plate, said front polarizer being crossed relative to said
`rear polarizer.
`In a first preferred embodiment, the first and second trans
`parent plates are made of glass, and the liquid crystal display
`panel is an active matrix liquid crystal display panel. In addi
`tion, the rear polarizer is a non-compensated linear polarizer,
`the front surface of which is adhered to the rear surface of the
`active matrix liquid crystal display panel with an index
`matched, pressure sensitive adhesive. The display further
`comprises an indium tin oxide thin film coating adapted to be
`used as a heating element, said coating being applied to the
`front surface of the second glass plate. The front surface of
`30
`said heating element is adhered to the rear surface of the rear
`polarizer with a silicone-based, index-matched, optical bond
`ing material.
`Said liquid crystal display further comprises an indium tin
`oxide thin film coating usable as an electromagnetic interfer
`ence (EMI) shield, said coating being applied to the rear
`surface of the first glass plate. The rear surface of said EMI
`coated glass substrate is adhered to the front surface of the
`active matrix liquid crystal display panel with the above
`mentioned silicone-based, index-matched, optical bonding
`material.
`The front polarizer is also a non-compensated linear polar
`izer, the front surface of which is adhered to a third glass plate
`with an index-matched, pressure sensitive adhesive and the
`rear surface of which is adhered to the front surface of the first
`glass plate by a layer of the above-mentioned silicone-based,
`index-matched, optical bonding material. The display further
`includes an anti-reflection (AR) thin film coating applied to
`the front surface of the third glass plate.
`50
`In order to minimize the reflection of ambient light by the
`display into the view of an observer, the various elements of
`the display preferably have respective indices of refraction
`that differ as minimally as possible.
`A second preferred embodiment differs from the first pre
`ferred embodiment in that a first compensation film is inter
`posed between the front polarizer and the index-matched
`optical bonding material used to bond the front polarizer to
`the first glass plate, and a second compensation film is inter
`posed between the rear polarizer and the index-matched pres
`sure-sensitive adhesive used to adhere the rearpolarizer to the
`liquid crystal display panel.
`A third preferred embodiment differs from the first pre
`ferred embodiment in that the following items are omitted:
`the EMI shield, the first glass plate, the optical bonding mate
`rial used to bond the front polarizer to the first glass plate, the
`heating element, the second glass plate and the optical bond
`
`99 &
`
`4
`ing material used to bond the rear polarizer to the heating
`element. In addition, the third glass plate may be a plastic
`plate.
`A fourth preferred embodiment differs from the third pre
`ferred embodiment in that the optical bonding material used
`to bond the front polarizer to the liquid crystal display is
`replaced with an air gap.
`A fifth preferred embodiment differs from the third pre
`ferred embodiment in that the anti-reflection coating is
`applied to the front surface of a thin film, the rear surface of
`said thin film being adhered to the front surface of the plastic
`plate by an index-matched pressure sensitive adhesive.
`A sixth preferred embodiment differs from the third pre
`ferred embodiment in that the plastic plate is replaced with a
`touch panel.
`Additional embodiments can be derived from a combina
`tion of the embodiments disclosed above.
`The terms “front, “in front of “front surface' or the like,
`when used herein to describe an element of a liquid crystal
`display or to denote the relative positions of two or more
`elements of a liquid crystal display, refer directionally to the
`viewer side of the liquid crystal display. The terms “behind.”
`“in back of “rear surface' or the like, when used herein to
`describe an element of a liquid crystal display or to denote the
`relative positions of two or more elements of a liquid crystal
`display, refer directionally to the side of the liquid crystal
`display facing away from the viewer, typically the backlight
`side of the display.
`Additional objects, features, aspects and advantages of the
`present invention will be set forth, in part, in the description
`which follows and, in part, will be obvious from the descrip
`tion or may be learned by practice of the invention. Certain
`embodiments of the invention will be described hereafter in
`sufficient detail to enable those skilled in the art to practice the
`invention, and it is to be understood that other embodiments
`may be utilized and that structural or other changes may be
`made without departing from the scope of the invention. The
`following detailed description is, therefore, not to be taken in
`a limiting sense, and the scope of the present invention is best
`defined by the appended claims.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The accompanying drawing, which is hereby incorporated
`into and constitutes a part of this specification, illustrates a
`preferred embodiment of the invention and, together with the
`description, serves to explain the principles of the invention.
`In the drawing wherein like reference numerals represent like
`parts:
`FIG. 1 is a schematic section view of a first embodiment of
`a liquid crystal display constructed according to the teachings
`of the present invention;
`FIG. 2 is a schematic section view of the liquid crystal
`display panel of the liquid crystal display of FIG. 1;
`FIG.3 is a schematic section view of a second embodiment
`of a liquid crystal display constructed according to the teach
`ings of the present invention;
`FIG. 4 is a schematic section view of one of the polarizer
`assemblies present in the liquid crystal display of FIG.3, said
`polarizer assembly being constructed according to the teach
`ings of the present invention;
`FIG. 5 is a schematic section view of the other of the
`polarizer assemblies present in the liquid crystal display of
`FIG. 3, said polarizer assembly being a conventional polar
`izer assembly;
`
`US 7,405,779 B2
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`US 7,405,779 B2
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`5
`FIG. 6 is a schematic section view of a third embodiment of
`a liquid crystal display constructed according to the teachings
`of the present invention;
`FIG. 7 is a schematic section view of a fourth embodiment
`of a liquid crystal display constructed according to the teach- 5
`ings of the present invention;
`FIG. 8 is a schematic section view of a fifth embodiment of
`a liquid crystal display constructed according to the teachings
`of the present invention; and
`FIG.9 is a schematic section view of a sixth embodiment of 10
`a liquid crystal display constructed according to the teachings
`of the present invention.
`
`DETAILED DESCRIPTION OF PREFERRED
`EMBODIMENTS
`
`15
`
`6
`strate 15. Coating 23, whose index of refraction substantially
`matches that of glass substrate 15, is preferably made of
`indium tin oxide or another suitable material so that, when
`coupled to a power source, coating 23 serves as a heating
`element to heat display 11 when it is used in cold ambient
`temperature conditions. The front surface of coating 23 is
`preferably adhered to the rear surface of rear polarizer 19 with
`a layer 25 of an index-matched, optical bonding material.
`Layer 25, which may be made of for example, a silicone
`based or epoxy-based, index-matched, optical bonding mate
`rial, eliminates any air gap between rear polarizer 19 and
`coating 23.
`Display 11 preferably further comprises an electromag
`netic interference (EMI) shield 27. EMI shield 27, which is
`preferably in the form of an indium tin oxide thin film coating
`applied to the rear surface of first glass substrate 13, shields
`LCD panel 17 from incoming electromagnetic radiation by
`absorbing said radiation. EMI shield 27 preferably has an
`index of refraction that substantially matches that of LCD
`panel 17, and the rear surface of EMI shield 27 is preferably
`adhered to the front surface of LCD panel 17 with a layer 29
`of the above-mentioned index-matched, optical bonding
`material.
`Display 11 also comprises a front polarizer 31, front polar
`izer 31 being similar to rear polarizer 19 but crossed relative
`thereto. Front polarizer 31 preferably has an index of refrac
`tion Substantially matching that of first glass Substrate 13, and
`the rear surface of front polarizer 31 is preferably adhered to
`the front surface of first glass substrate 13 by a layer 33 of the
`above-mentioned index-matched, optical bonding material.
`Display 11 additionally comprises a third glass Substrate
`35, which may be identical in composition to glass substrates
`13 and 15. Third glass substrate 35 preferably has index of
`refraction substantially matching that of front polarizer 31,
`and the rear surface of third glass substrate 35 is preferably
`bonded to the front of front polarizer 31 by a layer 37 of the
`above-mentioned index-matched, pressure sensitive adhe
`sive. (Layer 37 may be applied to polarizer 31 by the polar
`izer's manufacturer to form a polarizer assembly.) The
`peripheries of first glass Substrate 13, second glass Substrate
`15 and third glass substrate 35 are preferably externally
`sealed to contain those elements of display 11 sandwiched
`therebetween.
`Display 11 further includes a conventional anti-reflection
`thin film coating 39 applied (preferably by vapor deposition)
`to the front surface of third glass substrate 35. Coating 39.
`which is typically about 1-2 microns thick, may be made of
`for example, magnesium fluoride and/or quartz.
`Display 11 further includes a backlight 41, which may be
`conventional in nature, positioned behind second glass Sub
`Strate 15.
`Display 11 may be used in the conventional manner.
`Because of its construction, display 11 exhibits improved
`optical viewing performance.
`It should be understood that, although substrates 35, 13 and
`15 of display 11 are made of glass, one could replace one or
`more of substrates 35, 13 and 15 with a non-glass transparent
`material. Such as a polycarbonate or a like plastic; however,
`said replacement(s) would likely render the display unsuit
`able for most military applications—but not unsuitable for
`most commercial applications.
`Referring now to FIG.3, there is shown a schematic section
`view of a second embodiment of a liquid crystal display
`constructed according to the teachings of the present inven
`tion, said liquid crystal display being represented generally
`by reference numeral 51.
`
`25
`
`30
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`35
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`As noted above, the present invention is directed to the
`problem of poor viewing performance or “washout in liquid
`crystal displays, said problem occurring most notably under
`high ambient light conditions. More specifically, the problem
`is caused by the reflection of ambient light by the liquid
`crystal display back towards the viewer, thereby obscuring
`the image generated by the liquid crystal display. Moreover,
`in those instances in which the liquid crystal display includes
`an electromagnetic interference shield, often in the form of an
`indium tin oxide coating applied to the rear Surface of the
`front cover plate of the display, the problem of ambient light
`reflection into the view of an observer is made even more
`acute.
`Referring now to FIG.1, there is shown a schematic section
`view of a first embodiment of a liquid crystal display con
`structed according to the teachings of the present invention,
`said liquid crystal display being represented generally by
`reference numeral 11.
`Liquid crystal display 11, which is particularly well-suited
`for (but is not limited to) military applications, comprises a
`first glass Substrate 13, a second glass Substrate 15 and a
`liquid crystal display (LCD) panel 17, LCD panel 17 being
`positioned between glass substrates 13 and 15. Glass sub
`strates 13 and 15, which may be conventional in nature and
`correspond to the front and rear cover plates of a conventional
`liquid crystal display, typically have a thickness of about 0.04
`inch and may be made of a borosilicate, a Sodalime or the like.
`Preferably, glass substrates 13 and 15 have indices of refrac
`tion that substantially match that of LCD panel 17. LCD panel 45
`17, which is preferably (but not necessarily) an active matrix
`liquid crystal display (AMLCD) panel, may be conventional
`in nature.
`As shown in FIG. 2, LCD panel 17 typically includes a
`layer 12 of liquid crystals sandwiched between a pair of 50
`transparent plates 14-1 and 14-2, the inner Surfaces of plates
`14-1 and 14-2 being coated with a transparent conductive
`coating used to form transparent electrodes 16-1 and 16-2,
`respectively.
`Referring back to FIG. 1, display 11 also comprises a rear 55
`polarizer 19, rear polarizer 19 preferably having an index of
`refraction that substantially matches that of LCD panel 17.
`The front surface of rear polarizer 19 is preferably adhered to
`the rear surface of LCD panel 17 with a layer 21 of a conven
`tional index-matched, pressure sensitive adhesive (layer 21
`being about 0.001 inch in thickness). Rear polarizer 19 may
`be, for example, a conventional non-compensated linear
`polarizer, and layer 21 may be applied to polarizer 19 by the
`polarizer's manufacturer so that polarizer 19 and layer 21
`form a polarizer assembly.
`In addition, display 11 preferably comprises a thin film
`coating 23 applied to the front Surface of second glass Sub
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`Display 51, which is also particularly well-suited for (but
`not limited to) use in military applications, is similar in many
`respects to display 11, the principal differences between the
`two displays being that, in display 51, the combination of
`front polarizer 31 and adhesive 37 of display 11 are replaced
`with a polarizer assembly 71 and the combination of polarizer
`19 and adhesive 21 of display 11 are replaced with a polarizer
`assembly 81.
`Referring now to FIG.4, polarizer assembly 71 is shown in
`greater detail. Polarizer assembly 71 comprises a neutral den
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`sity polarizer 73, which may be conventional in nature. An
`index-matched, pressure sensitive adhesive 75, which may be
`conventional in nature, is applied to one side of polarizer 73,
`and a wide viewing angle film 77 (also known as a compen
`sation film), which may be conventional in nature, is applied
`to the opposite side of polarizer 73.
`In display 51, adhesive 75 is contacted with substrate 35,
`with film 77 adhered to material 33.
`Referring now to FIG. 5, polarizer assembly 81 is shown in
`greater detail. Assembly 81, which is conventional, com
`prises a wide viewing angle film 83, which may be identical to
`film 77. An index-matched, pressure sensitive adhesive 85.
`which may be identical to adhesive 75, is applied to one side
`of film 83, and a neutral density polarizer 87, which may be
`identical to polarizer 73 but is crossed relative thereto, is
`applied to the opposite side of film 83.
`In display 51, adhesive 85 of assembly 81 is placed in
`contact with panel 17, with polarizer 87 adhered to optical
`bonding material 25.
`One advantage to replacing polarizers 31 and 19 (and their
`associated pressure sensitive adhesives 37 and 21, respec
`tively) with assemblies 71 and 81, respectively, is that films
`77 and 83 serve to counter the birefringent effect of the liquid
`crystal material in panel 17, thereby improving the viewing
`characteristics of the display at wide angles.
`Referring now to FIG. 6, there is shown a schematic section
`view of a third embodiment of a liquid crystal display con
`structed according to the teachings of the present invention,
`said liquid crystal display being represented generally by
`reference numeral 101.
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`Display 101, which is particularly well-suited for non
`military or commercial applications (e.g., cellphone screens,
`laptop monitors), comprises a liquid crystal display (LCD)
`panel 105, LCD panel 105 being identical to LCD panel 17 of
`display 11.
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`Display 101 also comprises a rear polarizer109. The front
`surface of rear polarizer109 is adhered to the rear surface of
`LCD panel 105 with an index-matched, pressure-sensitive
`adhesive 111. Polarizer109 and adhesive 111 may be identi
`cal to polarizer 19 and adhesive 21, respectively, of device 11
`and may be manufactured together in the form of a polarizer
`assembly.
`Display 101 additionally comprises a front polarizer 115,
`front polarizer 115 being crossed relative to rear polarizer
`109. The rear surface of front polarizer 115 is adhered to the
`front surface of LCD panel 105 by a layer 119 of an index
`matched, optical bonding material, and an index-matched
`pressure sensitive adhesive 121 is applied to the front surface
`offront polarizer 115. Polarizer 115 and adhesive 121 may be
`identical to polarizer 31 and adhesive 37, respectively, of
`device 11 and may be manufactured together in the form of a
`polarizer assembly.
`Display 101 additionally comprises a transparent cover
`125, cover 125 preferably having an index of refraction sub
`stantially matching that of front polarizer 115. The rear sur
`face of cover 125 is preferably bonded to the front of polarizer
`115 by adhesive 121. Cover 125 is preferably made of a
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`Suitable plastic. Such as a polycarbonate, but can also be made
`of a glass (it being understood that glass is less Suitable for
`many commercial applications).
`Display 101 preferably further includes a conventional
`anti-reflection thin film coating 131 applied to the front sur
`face of cover 125. Coating 131 may be identical to coating 39
`of device 11.
`It is to be understood that, where cover 125 is made of
`plastic, coating 131 may be omitted and cover 125 may,
`instead, be textured to reduce glare.
`Display 101 preferably further includes a backlight 141,
`which may be conventional in nature, positioned behind
`polarizer109.
`As can readily be appreciated, polarizer 115 and adhesive
`121 of display 101 may be replaced with assembly 71, with
`polarizer 109 and adhesive 111 of display 101 also being
`replaced w