HK40031107A

HK40031107A - Display devices including photochromic-dichroic compounds and dichroic compounds

Info

Publication number: HK40031107A
Application number: HK62020020981.0A
Authority: HK
Inventors: A·库玛; K·W·塞伯特
Original assignee: Ppg工业俄亥俄公司
Priority date: 2017-10-19
Filing date: 2018-10-19
Publication date: 2021-03-05

Description

Display device comprising photochromic-dichroic compound and dichroic compound

Technical Field

The present invention relates to display elements and devices comprising photochromic-dichroic compounds and dichroic compounds.

Background

Displays on mobile devices, ATMs and other machines that may be used outdoors often have problems with respect to solar readability, UV degradation, durability, operating temperature range and lifetime. Sunlight readability can be improved in a number of ways. One solution is to actively increase the backlight intensity by adding more Cold Cathode Fluorescent Lamp (CCFL) backlight tubes. Unfortunately, this approach has drawbacks in most mobile device applications due to battery drain, larger device size, heat and weight considerations. The second approach is to passively increase backlight intensity by adding a brightness enhancement film to the optical stack of the display screen. While avoiding most of the disadvantages of the active approach, this solution only increases brightness by about a factor of two, which is not sufficient to solve the solar readability problem. A third solution is to minimize reflected light, such as by using antireflection coatings and films and circular polarizers. Each of these solutions can be combined with each other to optimize the desired effect.

Most mobile devices today use circular polarizers. A circular polarizer is a component of a conventional linear polarizing element and a quarter-wave retarder. The retarder axis is oriented at 45 degrees with respect to the linear polarizer axis. When incident light passes through the module, it is converted into circularly polarized light. Circular polarizers have traditionally been used because of their anti-reflective properties. In such applications, when light is reflected back from the mirror through the retarder, the plane of polarization is rotated 90 degrees relative to the original direction, so the linear polarizer blocks the reflected light back. However, in order to achieve solar readability, a circular polarizer must absorb a large amount of transmitted radiation, typically about 60% of the transmitted radiation being absorbed. While such high levels of absorbance are necessary for solar readability, a large amount of absorbance is not required indoors. However, the amount of absorbance of the circular polarizer is fixed, and therefore a high level of brightness must be emitted from the light emitting source to make the display of the cell phone visible and overcome the absorbance of the circular polarizer. This results in a considerable waste of battery energy.

It would be desirable to provide a display that provides good readability in both bright and dark conditions and improves the battery life of the display device.

Disclosure of Invention

Disclosed herein are display elements comprising a photochromic-dichroic compound and a dichroic compound, the display elements having a first absorption state and a second absorption state and being operable to switch from the first absorption state to the second absorption state in response to actinic radiation and to switch back to the first absorption state in response to actinic radiation and/or thermal energy, wherein the first absorption state has a percent transmission of from 50% to 80% and the second absorption state has a percent transmission of from 10% to 50%.

Also disclosed herein are display devices comprising a display element comprising a photochromic-dichroic compound and a dichroic compound, the display element having a first absorption state and a second absorption state and being operable to transition from the first absorption state to the second absorption state in response to actinic radiation and/or thermal energy and to transition back to the first absorption state in response to actinic radiation and/or thermal energy, wherein the first absorption state has a percent transmission of from 50% to 80% and the second absorption state has a percent transmission of from 10% to 50%.

Drawings

Fig. 1 is a layer stack configuration of a display element according to embodiment 1. The glass plates were coated with a photoalignment layer and a liquid crystal coating formulation (LCCF-1).

Fig. 2 is a layer stack configuration of a display element according to embodiment 2. The glass plate was coated with a photo-alignment layer, a liquid crystal coating formulation (LCCF-2), a second photo-alignment layer and a second liquid crystal coating formulation (LCCF-1).

Fig. 3 is a layer stack configuration of a display element according to embodiment 3. The glass plates were coated with a photoalignment layer and a liquid crystal coating formulation (LCCF-3).

Detailed Description

As described above, the present invention relates to a display element comprising a photochromic-dichroic compound and a dichroic compound, the display element having a first absorption state and a second absorption state and being operable to switch from the first absorption state to the second absorption state in response to actinic radiation and to switch back to the first absorption state in response to actinic radiation and/or thermal energy, wherein the first absorption state has a percent transmission of from 50% to 80% and the second absorption state has a percent transmission of from 10% to 50%.

According to the invention, the display element comprises a photochromic-dichroic compound. The photochromic-dichroic compound has a first absorption state and a second absorption state, wherein the photochromic-dichroic material switches from the first state to the second state in response to actinic radiation, switches back to the first state in response to actinic and/or thermal energy, and can exhibit linear polarization of both the first state and the second state. As used herein, the term "photochromic-dichroic" means exhibiting both photochromic and dichroic (i.e., linearly polarizing) properties under certain conditions, which properties are at least detectable by an instrument. Thus, a "photochromic-dichroic compound" is a compound that exhibits both photochromic and dichroic (i.e., linear polarization) properties under certain conditions, which properties are at least detectable by an instrument. As used herein, the term "linearly polarize" means to confine the vibration of the electric vector of a light wave to one direction. Thus, the photochromic-dichroic compound has an absorption spectrum for at least visible radiation that changes in response to at least actinic radiation, and is capable of absorbing at least one of the two orthogonal plane-polarized components of the transmitted radiation more strongly than the other. Thus, the display element may have an absorption spectrum of at least visible radiation that varies in response to at least actinic radiation, and may be capable of absorbing at least one of the two orthogonal plane-polarized components of transmitted radiation more strongly than the other.

The photochromic-dichroic compound of the display element can be unpolarized in the first state (i.e., the photochromic-dichroic compound does not limit the vibration of the electric vector of the light wave to one direction) and linearly polarize the transmitted radiation in the second state. As used herein, the term "transmitted radiation" refers to radiation that passes through at least a portion of an object. Although not limited herein, the transmitted radiation may be ultraviolet radiation, visible radiation, or a combination thereof. Thus, the photochromic-dichroic material can be unpolarized in the first state and linearly polarize transmitted ultraviolet radiation, transmitted visible radiation, or a combination thereof in the second state.

In addition, the photochromic-dichroic compounds disclosed herein can be thermally reversible. That is, the photochromic-dichroic compound can transition from a first state to a second state in response to actinic radiation and back to the first state in response to thermal energy.

Non-limiting examples of photochromic-dichroic compounds suitable for use in the display elements disclosed herein include the compounds listed below and the compounds described in U.S. Pat. No. 7,256,921 at column 19, line 26 to column 22, line 47, including:

(1) 3-phenyl-3- (4- (4- (3-piperidin-4-yl-propyl) piperidino (piperidino)) phenyl) -13, 13-dimethyl-indeno [2 ', 3': 3,4] -naphtho [1,2-b ] pyran;

(2) 3-phenyl-3- (4- (4- (3- (1- (2-hydroxyethyl) piperidin-4-yl) propyl) piperidino) phenyl) -13, 13-dimethyl-indeno [2 ', 3': 3,4] naphtho [1,2-b ] pyran;

(3) 3-phenyl-3- (4- (4- (4-butyl-phenylcarbamoyl) -piperidin-1-yl) phenyl) -13, 13-dimethyl-6-methoxy-7- (4-phenyl-piperazin-1-yl) indeno [2 ', 3': 3,4] naphtho [1,2-b ] pyran;

(4) 3-phenyl-3- (4- ([1,4 '] bipiperidinyl-1' -yl) phenyl) -13, 13-dimethyl-6-methoxy-7- ([1,4 '] bipiperidinyl-1' -yl) indeno [2 ', 3': 3,4] naphtho [1,2-b ] pyran;

(5) 3-phenyl-3- (4- (4-phenyl-piperazin-1-yl) phenyl) -13, 13-dimethyl-6-methoxy-7- (4- (4-hexylbenzoyloxy) -piperidin-1-yl) indeno [2 ', 3': 3,4] naphtho [1,2-b ] pyran; and

(6) 3-phenyl-3- (4- (4-phenyl-piperazin-1-yl) phenyl) -13, 13-dimethyl-6-methoxy-7- (4- (4 ' -octyloxy-biphenyl-4-carbonyloxy) -piperidin-1-yl) indeno [2 ', 3 ': 3,4] naphtho [1,2-b ] pyran.

More generally, the photochromic-dichroic compound may comprise (a) at least one photochromic group (PC) selected from pyrans, oxazines and fulgides; and (b) at least one extender attached to the photochromic group, wherein extender (L) is represented by formula I below (which is described in detail below):

—[S₁]_c-[Q₁-[S₂]_d]_d′-[Q₂-[S₃]_e]_e′-[Q₃-[S₄]_f]_f′—S₅-P formula I

As used herein, the term "linked" means directly bonded to or indirectly bonded through another group. Thus, for example, L may be directly bonded to PC as a substituent on PC, or L may be another group (as discussed below by R) directly bonded to PC¹The group represented) is not present (i.e., L is indirectly bonded to PC). Although not limited herein, L may be linked to PC to expand or lengthen the PC in an activated state such that the absorbance of the expanded PC (i.e., the photochromic compound) is enhanced as compared to PC alone. Although not limited herein, the location of the connection of L to PC may be selected such that L elongates PC in at least one of a direction parallel and perpendicular to the theoretical transient dipole moment of the activated form of PC. As used herein, the term "theoretical transient dipole moment" refers to the transient dipole polarization resulting from the interaction of electromagnetic radiation with molecules. See, for example, IUPAC Complex of Chemical Technology,2^ndEd.,International Union of Pure and Applied Chemistry(1997)。

With respect to the above formulae I, Q₁、Q₂And Q₃Each of (a) may be independently selected at each occurrence from:a divalent group selected from the group consisting of unsubstituted or substituted aromatic groups, unsubstituted or substituted alicyclic groups, unsubstituted or substituted heterocyclic groups, and mixtures thereof, wherein the substituents are selected from the group consisting of: a group represented by P (as explained below), liquid crystal mesogen, halogen, poly (C)₁-C₁₈Alkoxy) C₁-C₁₈Alkoxycarbonyl radical, C₁-C₁₈Alkylcarbonyl group, C₁-C₁₈Alkoxycarbonyloxy, aryloxycarbonyloxy, perfluoro (C)₁-C₁₈) Alkoxy, perfluoro (C)₁-C₁₈) Alkoxycarbonyl, perfluoro (C)₁-C₁₈) Alkylcarbonyl, perfluoro (C)₁-C₁₈) Alkylamino, di- (perfluoro (C)₁-C₁₈) Alkyl) amino, perfluoro (C)₁-C₁₈) Alkylthio radical, C₁-C₁₈Alkylthio radical, C₁-C₁₈Acetyl group, C₃-C₁₀Cycloalkyl radical, C₃-C₁₀Cycloalkoxy, by cyano, halo or C₁-C₁₈Alkoxy-monosubstituted or halogenopolysubstituted straight-chain or branched C₁-C₁₈An alkyl group, and a group represented by one of the following formulae: -M (T)_(t-1)and-M (OT)_(t-1)Wherein M is selected from the group consisting of aluminum, antimony, tantalum, titanium, zirconium, and silicon, T is selected from the group consisting of organofunctional groups, organofunctional hydrocarbon groups, aliphatic hydrocarbon groups, and aromatic hydrocarbon groups, and T is the compound state of M. As used herein, the prefix "poly" means at least two.

As discussed above, Q₁、Q₂And Q₃May be independently selected at each occurrence from divalent groups such as unsubstituted or substituted aromatic groups, unsubstituted or substituted heterocyclic groups, and unsubstituted or substituted alicyclic groups. Examples of useful aromatic groups include: benzo, naphtho, phenanthro, biphenyl, tetrahydronaphtho, terphenyl, and anthraceno.

As used herein, the term "heterocyclic group" means a compound having a ring of atoms in which at least one of the atoms forming the ring is different from the other atoms forming the ring. In addition, as used herein, the term heterocyclic group is especially intended to includeCondensed heterocyclic groups are excluded. Q₁、Q₂And Q₃Examples of suitable heterocyclic groups which may be selected from among these include: isosorbide, dibenzofuro, dibenzothieno, benzofuro, benzothieno, thieno, furo, dioxino, carbazolo, anthranoyl (anthracenyl), azaRadicals, benzoxazolyl, diazepineExamples of the substituent include a group selected from the group consisting of a phenyl group, a naphthyl group, an imidazolidinyl group, an imidazolyl group, an imidazolinyl group, an indazolyl group, a pseudoindolyl group, an indolinyl group, an indolizinyl group, an isoindolyl group, an isoindolinyl group, an isoindolyl group, an isoxazolyl group, an isooxazyl group, an isopyrrolyl group, an isoquinolyl group, an isothiazolyl group, a morpholino group, a morpholinyl group, an oxadiazolyl group, an oxathiazolyl group, an oxathizyl group, an oxathiadienyl group, an oxatriazolyl group, an oxazolyl group, a piperazinyl group, a piperazyl group, a piperidinyl group, a purinyl group, a pyranopyrrolyl group, a pyrazinyl group, a pyrazolidinyl group, a pyrazolinyl group, a pyrazolyl group, a pyrazyl group, a pyridazinyl group, a pyridazyl group, a pyrimidinyl group, a pyrimidyl group, a pyridinyl group, a pyrrolidinyl group, a pyrrolinyl group, a quinuclidinyl group, a quinolinyl group, a thiazolyl group, a triazolyl group, a triazyl, Tetrahydroquinolino, tetrahydroisoquinolino, pyrrolyl, unsubstituted, monosubstituted or disubstituted C₄-C₁₈Spirobicyclic amines and unsubstituted, monosubstituted or disubstituted C₄-C₁₈A spirotricyclic amine.

As discussed above, Q₁、Q₂And Q₃May be selected from mono-or di-substituted C₄-C₁₈Spirobicyclic amines and C₄-C₁₈A spirotricyclic amine. Examples of suitable substituents include aryl, C₁-C₆Alkyl radical, C₁-C₆Alkoxy or phenyl (C)₁-C₆) An alkyl group. MonosubstitutedOr disubstituted spirobicyclic amines, include: 2-azabicyclo [2.2.1]Hept-2-yl; 3-azabicyclo [3.2.1]Oct-3-yl; 2-azabicyclo [2.2.2]Oct-2-yl; and 6-azabicyclo [3.2.2]Non-6-yl. Specific examples of mono-or di-substituted tricyclic amines include: 2-azatricyclo [3.3.1.1(3,7)]Decan-2-yl; 4-benzyl-2-azatricyclo [3.3.1.1(3,7)]Decan-2-yl; 4-methoxy-6-methyl-2-azatricyclo [3.3.1.1(3,7)]Decan-2-yl; 4-azatricyclo [4.3.1.1(3,8)]Undecan-4-yl; and 7-methyl-4-azatricyclo [4.3.1.1(3,8)]Undecan-4-yl. Q₁、Q₂And Q₃Examples of cycloaliphatic groups from which they may be selected include, but are not limited to, cyclohexyl, cyclopropyl, norbornenyl, decahydronaphthyl, adamantyl, bicyclooctane, perhydrofluorene, and cubic alkyl.

With continued reference to formula I, each S₁、S₂、S₃、S₄And S₅Can be independently selected at each occurrence from a spacer unit from the group consisting of:

(1)—(CH₂)_g—、—(CF₂)_h—、—Si(CH₂)_g—、—(Si[(CH₃)₂]O)_hwherein g is independently at each occurrence selected from 1 to 20; h is selected from 1 to 16;

(2) -N (Z) -, — C (Z) ═ N, — C (Z ') -or a single bond, wherein Z is independently selected at each occurrence from hydrogen, C (Z') -, or a single bond₁-C₁₈Alkyl radical, C₃-C₁₀Cycloalkyl and aryl, and Z' is independently at each occurrence selected from C₁-C₁₈Alkyl radical, C₃-C₁₀Cycloalkyl and aryl groups; and

(3) -O- (O) -, -C (O) -, -C.ident.C) -, -N ═ N- (S) -, -S (O) -, -O) S (O) -, -O (O) S (O) -, or linear or branched C (O) -, -O (O) (-) S (O) -) O-or linear or branched C (O) -, -S (O) (-) -, -S (O₁-C₂₄Alkylene residue of said C₁-C₂₄An alkylene residue is unsubstituted, mono-substituted by cyano or halo, or poly-substituted by halo; provided that when two heteroatom-containing spacer units are linked together, the spacer units are linked such that the heteroatomsAtoms are not directly attached to each other, and when S₁And S₅When attached to PC and P, respectively, they are attached such that the two heteroatoms are not directly attached to each other. As used herein, the term "heteroatom" means an atom other than carbon or hydrogen.

Additionally, in formula I, c, d, e, and f may each be independently selected from integers in the range of 1 to 20, inclusive; and d ', e' and f 'may each be independently selected from 0, 1,2, 3 and 4, provided that the sum of d' + e '+ f' is at least 1. According to the invention, c, d, e and f may each be independently selected from integers in the range of 1 to 20 inclusive; and d ', e' and f 'may each be independently selected from 0, 1,2, 3 and 4, provided that the sum of d' + e '+ f' is at least 2. According to the invention, c, d, e and f may each be independently selected from integers in the range of 1 to 20 inclusive; and d ', e' and f 'may each be independently selected from 0, 1,2, 3 and 4, provided that the sum of d' + e '+ f' is at least 3. According to the invention, c, d, e and f may each be independently selected from integers in the range of 1 to 20 inclusive; and d ', e' and f 'may each be independently selected from 0, 1,2, 3 and 4, provided that the sum of d' + e '+ f' is at least 1.

Additionally, in formula I, P may be selected from: hydroxy, amino, C₂-C₁₈Alkenyl radical, C₂-C₁₈Alkynyl, azido, silyl, siloxane, silyl hydride, (tetrahydro-2H-pyran-2-yl) oxy, thio, isocyanato, thioisocyanato, acryloxy, methacryloxy, 2- (acryloxy) ethylcarbamoyl, 2- (methacryloxy) ethylcarbamoyl, aziridinyl, allyloxycarbonyloxy, epoxy, carboxylic acid ester, acryloylamino, methacryloylamino, aminocarbonyl, C₁-C₁₈Alkylaminocarbonyl, aminocarbonyl (C)₁-C₁₈) Alkyl radical, C₁-C₁₈Alkoxycarbonyloxy, halocarbonyl, hydrogen, aryl, hydroxy (C)₁-C₁₈) Alkyl radical, C₁-C₁₈Alkyl radical, C₁-C₁₈Alkoxy, amino (C)₁-C₁₈) Alkane (I) and its preparation methodBase, C₁-C₁₈Alkylamino, di- (C)₁-C₁₈) Alkylamino radical, C₁-C₁₈Alkyl radical (C)₁-C₁₈) Alkoxy radical, C₁-C₁₈Alkoxy (C)₁-C₁₈) Alkoxy, nitro, poly (C)₁-C₁₈) Alkyl ether, (C)₁-C₁₈) Alkyl radical (C)₁-C₁₈) Alkoxy (C)₁-C₁₈) Alkyl, polyethenoxy, polypropoxy, vinyl, acryloyl, acryloyloxy (C)₁-C₁₈) Alkyl, methacryloyl, methacryloyloxy (C)₁-C₁₈) Alkyl, 2-chloropropenoyl, 2-phenylpropenoyl, acryloxyphenyl, 2-chloropropenoylamino, 2-phenylpropenoylaminocarbonyl, oxetanyl, glycidyl, cyano, isocyanato (C)₁-C₁₈) Alkyl, itaconate, vinyl ether, vinyl ester, styrene derivatives, main and side chain liquid crystalline polymers, siloxane derivatives, ethyleneimine derivatives, maleic acid derivatives, fumaric acid derivatives, unsubstituted cinnamic acid derivatives, cinnamic acid derivatives substituted with at least one of methyl, methoxy, cyano and halogen, or substituted or unsubstituted chiral or achiral mono or divalent groups selected from the group consisting of steroid groups, terpene groups, alkaloid groups and mixtures thereof, wherein the substituents are independently selected from the group consisting of C₁-C₁₈Alkyl radical, C₁-C₁₈Alkoxy, amino, C₃-C₁₀Cycloalkyl radical, C₁-C₁₈Alkyl radical (C)₁-C₁₈) Alkoxy, fluoro (C)₁-C₁₈) Alkyl, cyano (C)₁-C₁₈) Alkyl, cyano (C)₁-C₁₈) Alkoxy groups or mixtures thereof, or P is a structure having 2 to 4 reactive groups or P is an unsubstituted or substituted ring-opening ectopic polymerization precursor.

In addition, although not limited herein, when P is a polymerizable group, the polymerizable group can be any functional group suitable for participating in a polymerization reaction. Examples of polymerization reactions include those described in the definition of "polymerization" in Hawley's condensed chemical reaction, Edition,1997, John Wiley & Sons, page 901-902, which disclosure is incorporated herein by reference. For example, although not limited herein, polymerization reactions include: "addition polymerization", wherein a free radical is an initiator which reacts with the double bond of the monomer by adding it on one side of the double bond of the monomer while generating a new free electron on the other side; "condensation polymerization" in which two reactive molecules combine to form a larger molecule with the elimination of a small molecule such as a water molecule; and "oxidative coupling polymerization". In addition, examples of the polymerizable group include a hydroxyl group, an acryloyloxy group, a methacryloyloxy group, a 2- (acryloyloxy) ethylcarbamoyl group, a 2- (methacryloyloxy) ethylcarbamoyl group, an isocyanate, an aziridine, an allyl carbonate, and an epoxy group such as an ethylene oxide methyl group.

Furthermore, P may be selected from main or side chain liquid crystalline polymers and liquid crystalline mesogens. As used herein, the term liquid crystal "mesogen" means a rigid rod-like or discotic liquid crystal molecule. In addition, as used herein, the term "backbone liquid crystalline polymer" refers to a polymer having liquid crystalline mesogens within the backbone (i.e., main chain) structure of the polymer. As used herein, the term "side chain liquid crystalline polymer" refers to a polymer having a liquid crystalline mesogen attached to the polymer at a side chain. Although not limited herein, typically the mesogen is composed of two or more aromatic rings that restrict the motion of the liquid crystal polymer. Examples of suitable rod-like liquid crystalline mesogens include, without limitation: substituted or unsubstituted aromatic esters, substituted or unsubstituted linear aromatic compounds, and substituted or unsubstituted terphenyls. According to the invention, P may be selected from steroids, such as, and without limitation, cholesterol compounds.

Examples of thermally reversible photochromic pyrans from which the photochromic group PC may be selected include benzopyrans, naphthopyrans such as naphtho [1,2-b ] pyran, naphtho [2,1-b ] pyran, indeno-fused naphthopyrans, such as those disclosed in U.S. Pat. No. 5,645,767, and heterocycle-fused naphthopyrans, such as those disclosed in U.S. Pat. nos. 5,723,072, 5,698,141, 6,153,126, and 6,022,497, which are incorporated herein by reference; spiro-9-fluoreno [1,2-b ] pyran; phenanthropyran; a quinolopyran; fluoranthene-benzopyran; spiropyrans such as spiro (benzindoline) naphthopyrans, spiro (indoline) benzopyrans, spiro (indoline) naphthopyrans, spiro (indoline) quinopyrans and spiro (indoline) pyrans. More specific examples of naphthopyrans and complementary organic photochromic substances are described in U.S. patent No. 5,658,501, which is specifically incorporated herein by reference. Spiro (indoline) pyrans are also described in the text Techniques in Chemistry, volume III, "photochromym", chapter 3, edited by Glenn h.brown, John Wiley and Sons, inc.

Examples of photochromic oxazines from which the PC may be selected include benzoxazines, naphthoxazines and spiro oxazines, such as spiro (indoline) naphthoxazines, spiro (indoline) pyridobenzoxazines, spiro (indoline) naphthoxazines, spiro (indoline) benzoxazines, spiro (indoline) fluoranthenoxazines and spiro (indoline) quinolinoxazines. Examples of photochromic fulgides from which PC may be selected include: fulgimides, 3-furyl and 3-thienyl fulgimides and fulgimides, which are disclosed in U.S. Pat. No. 4,931,220, which is incorporated herein by reference, and mixtures of any of the above photochromic materials/compounds.

In addition, where the photochromic-dichroic compound comprises at least two PCs, the PCs can be linked to each other via a linking group substituent on a single PC. For example, the PC may be a polymerizable photochromic group or a photochromic group suitable for compatibility with the host material ("compatible photochromic group"). Examples of polymerizable photochromic groups from which PC may be selected include those disclosed in U.S. patent No. 6,113,814, which is specifically incorporated herein by reference. Examples of compatible photochromic groups from which PC can be selected include those disclosed in U.S. patent No. 6,555,028, which is specifically incorporated herein by reference.

Other suitable photochromic groups and complementary photochromic groups are described in U.S. patent No. 6,080,338, column 2, line 21 to column 14, line 43; 6,136,968, column 2, line 43 to column 20, line 67; 6,296,785 column 2, line 47 to column 31, line 5; 6,348,604, column 3, line 26 to column 17, line 15; 6,353,102, column 1, line 62 to column 11, line 64; and 6,630,597, column 2, line 16 to column 16, line 23; the disclosures of the foregoing patents are incorporated herein by reference.

The photochromic compound may additionally comprise, in addition to the at least one extender (L), at least one other monomer R directly bonded to the PC¹The group shown. Although not required, the at least one extender (L) may be extended by at least one of R¹The group represented is indirectly bonded to PC. That is, L may be at least one group R bonded to PC¹A substituent as defined above. According to the invention, R¹Substituents disclosed in U.S. Pat. No. 7,256,921, column 26, line 60 to column 30, line 64, may be independently selected at each occurrence. Photochromic-dichroic compounds of the present invention include the compounds and methods of preparation disclosed in U.S. Pat. No. 7,256,921, column 30, line 65 to column 66, line 60, the portions of which are incorporated herein by reference.

In addition, as discussed in more detail below, the photochromic-dichroic compounds can be at least partially aligned.

According to the present invention, the photochromic-dichroic compound of the present invention may comprise a plurality of photochromic-dichroic compounds. Although not limited herein, when two or more photochromic-dichroic compounds are used in combination, the photochromic-dichroic compounds may be selected to be complementary to each other to produce a desired color or hue. For example, mixtures of photochromic-dichroic compounds can be used to obtain certain active colors, such as near neutral gray or near neutral brown. See, for example, U.S. patent No. 5,645,767, column 12, line 66 to column 13, line 19, the disclosures of which are specifically incorporated herein by reference, which describes parameters defining neutral gray and brown. Additionally or alternatively, the photochromic-dichroic compound can comprise a mixture of photochromic-dichroic compounds having complementary linear polarization states. For example, photochromic-dichroic compounds can be selected to have complementary linear polarization states in a desired wavelength range to produce a display element capable of polarizing light in the desired wavelength range. Still further, a mixture of complementary photochromic-dichroic compounds having substantially the same polarization state at the same wavelength may be selected to enhance or emphasize the resulting bus polarization. For example, the photochromic-dichroic compound can comprise at least two at least partially aligned photochromic-dichroic compounds, wherein the photochromic-dichroic compounds have complementary colors and/or complementary linear polarization states.

According to the invention, the display element comprises a dichroic compound. As used herein, the term "dichroic" means capable of absorbing one of the two orthogonal plane polarization components of transmitted radiation stronger than the other. Unlike photochromic-dichroic compounds, dichroic compounds have a fixed state of absorption and a fixed degree of linear polarization that does not change in response to exposure to actinic radiation. According to the present invention, the dichroic compound may comprise a plurality of dichroic compounds. Furthermore, as discussed in detail below, the dichroic compounds may be at least partially aligned.

Dichroic compounds may include azomethines, indigoids, thioindigoids, cyanines, indanes, quinophthalone dyes, perylenes, phthaleins, triphendioxazines, indoloquinoxalines, imidazotriazines, tetrazines, azo and (poly) azo dyes, benzoquinones, naphthoquinones, anthraquinones and (poly) anthraquinones, anthrapyrimidinones, iodine and iodates. The dichroic compound can be a polymerizable dichroic compound. That is, the dichroic compound may comprise at least one group capable of being polymerized (i.e., a "polymerizable group"). For example, although not limited herein, the dichroic compound can comprise at least one alkoxy, polyalkoxy, alkyl, or polyalkyl substituent that is capped with at least one polymerizable group. The dichroic compound may also comprise a plurality of these compounds.

Suitable commercially available anthraquinone dyes include the Blue dyes Blue AB2, Blue AB3 and Blue AB4, the Yellow dye Yellow AG1, the Orange dye Orange AO1, the Red dye Red AR1, and the Cyan dye Cyan AC1, each of which is available from Nematel GmbH & co. Suitable commercially available AZO dyes include the Orange dye Orange AZO1, available from Nematel GmbH & co.

As discussed above, the display elements of the present invention have a first absorption state and a second absorption state and are operable to transition from the first absorption state to the second absorption state in response to actinic radiation and/or thermal energy and transition back to the first absorption state in response to actinic radiation and/or thermal energy. According to the present invention, as used herein to modify the term "state," the terms "first" and "second" are not intended to refer to any particular order or chronology (chronology), but rather to two different conditions or properties. For example, although not limited herein, the first and second states of the display element may differ in at least one optical property, such as, but not limited to, linear polarization or absorbance/transmittance of visible and/or UV radiation. Thus, the display element may be adapted to have a different absorption spectrum in each of the first and second states. For example, although not limited herein, the display element may be adapted to have a first color in a first state and a second color in a second state. In addition, the display element may be adapted to have a first level of transmissivity in the first state and a reduced level of transmissivity in the second state.

The nature of the first absorption state of the display element is typically determined by dichroic compounds. Although the photochromic-dichroic compound present in the display element can linearly polarize transmitted radiation in the first absorption state, any amount of linear polarization provided by the photochromic-dichroic compound will be complementary to the more powerful absorption/linear polarization provided by the dichroic compound in the first absorption state. Conversely, the nature of the second absorption state of the display element is typically determined by and supplemented by the photochromic-dichroic compound. Upon activation of the photochromic-dichroic compound to reach the second absorption state of the display element, the absorption/linear polarization provided by the photochromic-dichroic compound is more powerful than the dichroic compound.

The first absorption state may have a percent transmittance (% T) of at least 50%, such as at least 55%, such as at least 60%, and may have a percent transmittance of no greater than 80%, such as no greater than 75%, such as no greater than 70%. The first absorption state may have a percent transmittance of 50% to 80%, such as 55% to 75%, such as 60% to 70%.

The second absorption state may have a percent transmittance of at least 10%, such as at least 12%, such as at least 15%, and may have a percent transmittance of no greater than 50%, such as no greater than 45%, such as no greater than 40%. The second absorption state may have a percent transmission of 10% to 50%, such as 12% to 45%, such as 15% to 40%.

As used herein, the terms "percent transmittance" and "% T" refer to photopic visual transmittance (photopic transmission), and in particular to the fraction of incident electromagnetic power in the visible spectrum (wavelengths 390nm to 700 nm) that is transmitted through a body, such as a display element, multiplied by 100%. Percent transmittance can be measured by: light is passed through the body, the intensity is recorded using a spectrophotometer, the value is divided by the intensity of light passed through the blank (i.e., without the body) as measured by the spectrophotometer, and the value is multiplied by 100%. Percent transmittance,% T may be represented by the following equation 1:

％T＝P/P₀100% (equation 1)

Wherein P is the sum of the intensity of light after passing through the body and P₀Is the intensity of light as it passes through the blank. Embodiments provide methods for measuring percent transmittance.

The first absorption state may have a linear polarization efficiency of at least 5%, such as at least 10%, such as at least 15%, and may have a linear polarization efficiency of no more than 70%, such as no more than 60%, such as no more than 50%. The first absorption state may have a linear polarization efficiency of 5% to 70%, such as 10% to 60%, such as 15% to 50%.

The second absorption state may have a linear polarization efficiency of at least 55%, such as at least 65%, such as at least 70%, and may have a linear polarization efficiency of no more than 99.9%, such as no more than 90%, such as no more than 80%. The second absorption state may have a linear polarization efficiency of 55% to 99.9%, such as 65% to 90%, such as 70% to 80%.

As used herein, the term "linear polarization efficiency" refers to the percentage of incident electromagnetic radiation that a body, such as a display element, transmits in an intended polarization state. For example, a body with a linear polarization efficiency of 99% transmits 99% of incident electromagnetic radiation in a desired polarization state (e.g., p-polarized or s-polarized) and 1% of incident electromagnetic radiation in the opposite polarization state.

The weight ratio of dichroic compound to photochromic-dichroic compound can be at least 0.005:1, such as at least 0.010:1, such as at least 0.015:1, and can be no greater than 0.150:1, such as no greater than 0.120:1, such as no greater than 0.090: 1. The weight ratio of dichroic compound to photochromic-dichroic compound can be from 0.005:1 to 0.150:1, such as from 0.010:1 to 0.120:1, such as from 0.015:1 to 0.090: 1.

According to the present invention, the display element may comprise a substrate, a sheet, a coating, or any combination thereof. The display element may include a single substrate or sheet comprising the photochromic-dichroic compound and the dichroic compound. The display element can further comprise at least one substrate and/or at least one sheet, wherein the substrate or at least one sheet optionally comprises at least one coating, and if present, at least one of the one or more substrates, the one or more sheets, and/or the one or more coatings comprises a photochromic-dichroic compound, and if present, at least one of the one or more substrates, the one or more sheets, and/or the one or more coatings comprises a dichroic compound. Any of the one or more substrates, the one or more sheets, and/or the one or more coatings of the display element can comprise a photochromic-dichroic compound, a dichroic compound, or both a photochromic-dichroic compound and a dichroic compound. Additionally, the plurality of substrates, sheets, and/or coatings of the display element can comprise photochromic-dichroic compounds, or combinations thereof. In addition, the display element may include other layers that do not contain photochromic-dichroic compounds or dichroic compounds. In general, the substrate, sheet, and coating may each independently be referred to as a "layer".

Thus, the display element may comprise a substrate comprising a photochromic-dichroic compound and a dichroic compound. The display element can further include at least one sheet coupled to the substrate, wherein the substrate and/or at least one of the one or more sheets comprises at least one of a photochromic-dichroic compound and/or a dichroic compound. The display element may comprise at least one coating on the substrate, wherein the substrate and/or at least one of the one or more coatings comprises at least one photochromic-dichroic compound and/or dichroic compound. The display element can comprise a substrate attached to at least one sheet that additionally comprises at least one coating on at least one of the substrate and/or one or more sheets, wherein at least one of the substrate, the one or more sheets, and/or the one or more coatings comprises at least one of a photochromic-dichroic compound and/or a dichroic compound. In addition, any of the display elements described in this paragraph can include more than one substrate.

The display element may include a sheet including a photochromic-dichroic compound and a dichroic compound. The display element may include a plurality of sheets, wherein at least one of the sheets comprises a photochromic-dichroic compound and a dichroic compound. The display element can include at least one sheet that additionally includes at least one coating on the at least one sheet, wherein at least one of the one or more sheets and/or the one or more coatings comprises a photochromic-dichroic compound and a dichroic compound.

As used herein, the term "sheet" refers to a preformed film having a generally uniform thickness and being capable of being self-supporting. Examples of polymer sheets that may be used in the display element include, but are not limited to, stretched polymer sheets, ordered liquid crystal polymer sheets, and photo-oriented polymer sheets. Examples of polymeric materials other than liquid crystal materials and photo-alignment materials that can be used to form the polymeric sheet include, but are not limited to, polyvinyl alcohol, polyvinyl chloride, polyurethane, polyacrylate, and polycaprolactam.

As used herein, the term "coating" means a support film derived from a flowable composition, which may or may not have a uniform thickness, and specifically excludes polymeric sheets. The coating may comprise an anisotropic material that is at least partially ordered. As used herein, the term "anisotropic" means having at least one property that differs in value when measured in at least one different direction. Thus, an "anisotropic material" is a material that has at least one property that differs in value when measured in at least one different direction. Examples of anisotropic materials suitable for use in the present invention include, but are not limited to, liquid crystal materials.

Additionally, the term "connected to" or "(at … …) as used herein means directly contacting the object or contacting the object through one or more other structures or materials, at least one of which directly contacts the object. Thus, the coating or sheet may directly contact at least a portion of the substrate or it may indirectly contact at least a portion of the substrate through one or more other structures or materials. For example, although not limited herein, the coating or sheet can contact one or more other at least partial coatings, polymeric sheets, or combinations thereof, at least one of which directly contacts at least a portion of the substrate.

Suitable substrates for use in the display element include, but are not limited to, substrates formed from organic materials, inorganic materials, or combinations thereof (e.g., composites). Non-limiting examples of substrates are described in more detail below.

Specific examples of organic materials that can be used to form the substrates disclosed herein include polymeric materials such as homopolymers and copolymers prepared from monomers and mixtures of monomers disclosed in U.S. Pat. No. 5,962,617 and in U.S. Pat. No. 5,658,501, column 15, line 28 to column 16, line 17, the disclosures of which are specifically incorporated herein by reference. For example, such polymeric materials may be thermoplastic or thermoset polymeric materials, may be transparent or optically clear, and may have any refractive index desired. Examples of such disclosed monomers and polymers include: polyol (allyl carbonate) monomers, such as allyl diglycol carbonate, e.g., diethylene glycol bis (allyl carbonate), sold under the trademark CR-39 by PPG Industries, inc; polyurea-polyurethane (polyurea-urethane) polymers, for example prepared by reacting a polyurethane prepolymer and a diamine curing agent, a composition of one such polymer is sold under the trademark TRIVEX by PPG Industries, inc; a polyol (meth) acryloyl terminated carbonate monomer; diethylene glycol dimethacrylate monomer; ethoxylated phenol methacrylate monomers; diisopropenyl benzene monomer; ethoxylated trimethylolpropane triacrylate monomers; ethylene glycol dimethacrylate monomer; a poly (ethylene glycol) dimethacrylate monomer; a urethane acrylate monomer; poly (ethoxylated bisphenol a dimethacrylate); poly (vinyl acetate); poly (vinyl alcohol); poly (vinyl chloride); poly (vinylidene chloride); polyethylene; polypropylene; a polyurethane; polythiourethane; thermoplastic polycarbonates, such as the carbonate-linked resins derived from bisphenol a and phosgene, one such material being sold under the trademark LEXAN; polyester, such as the material sold under the trademark MYLAR; poly (ethylene terephthalate); polyvinyl butyral; poly (methyl methacrylate), such as the material sold under the trademark PLEXIGLAS; and polymers prepared by reacting a polyfunctional isocyanate with a polythiol or polysulfide monomer, which can be homopolymeric or copolymeric and/or trimeric with the polythiol, polyisocyanate, polyisothiocyanate, and optionally ethylenically unsaturated monomer or halogenated aromatic-containing vinyl monomer. Copolymers of such monomers and blends of the described polymers and copolymers with other polymers are also contemplated, for example to form block copolymers or interpenetrating network products.

Other examples of organic materials suitable for forming the substrate include both synthetic and natural organic materials, including but not limited to: opaque or translucent polymeric materials, natural and synthetic fabrics, and cellulosic materials, such as paper and wood.

Examples of inorganic materials suitable for forming the substrate include glass, minerals, ceramics, and metals. For example, the substrate may comprise glass. The substrate may have a reflective surface, such as a polished ceramic, metal or mineral substrate. The substrate may include a reflective coating or layer deposited or otherwise applied to the surface of the inorganic or organic substrate to make it reflective or to enhance its reflectivity.

In addition, the substrates may have a protective coating on their outer surface, such as, but not limited to, an abrasion resistant coating, such as a "hard coating.

Still further, the substrate may optionally be an uncolored, colored, linearly polarized, circularly polarized, elliptically polarized, photochromic, or colored photochromic substrate. For example, as discussed above, the substrate may comprise a photochromic-dichroic compound and/or dichroic compound and thus will be linearly polarized in the first state and/or the second state. As used herein with respect to a substrate, the term "uncolored" means a substrate that is substantially free of colorant additions (such as, but not limited to, conventional dyes) and has an absorption spectrum for visible radiation that does not change significantly in response to actinic radiation. Additionally, with respect to the substrate, the term "colored" means a substrate having an absorption spectrum for visible radiation that is additive to a colorant (such as, but not limited to, conventional dyes) and does not change significantly in response to actinic radiation.

As used herein, the term "linearly polarizing" with respect to a substrate refers to a substrate suitable for linearly polarizing radiation. As used herein, the term "circularly polarized" with respect to a substrate refers to a substrate suitable for circularly polarized radiation. As used herein, the term "elliptically polarized" with respect to a substrate refers to a substrate suitable for elliptically polarized radiation. As used herein, the term "photochromic" with respect to a substrate refers to a substrate having an absorption spectrum of visible radiation that changes in response to at least actinic radiation. Additionally, as used herein, the term "tinted photochromism" with respect to a substrate means a substrate that contains colorant additions as well as photochromic materials and has an absorption spectrum for visible radiation that changes in response to at least actinic radiation. Thus, for example and without limitation, a tinted photochromic substrate may have a first color characteristic of a colorant and a second color characteristic of a combination of the colorant and the photochromic material upon exposure to actinic radiation.

As discussed previously, while the photochromic-dichroic compounds and dichroic compounds can be linearly polarizing in the first and/or second states, it is generally desirable to properly position or arrange the molecules of the photochromic-dichroic compounds or dichroic compounds so as to achieve the net linear polarizing effect produced by the photochromic-dichroic compounds or dichroic compounds. Thus, as discussed above, the photochromic-dichroic compounds may be at least partially aligned, and the dichroic compounds may be at least partially aligned. The dichroic compound may optionally be at least partially aligned with the photochromic-dichroic compound, or the compounds may be independently aligned.

According to the invention, the display element may comprise at least one at least partially ordered alignment layer. The alignment layer may at least partially align or order the photochromic-dichroic compounds and/or dichroic compounds. As used herein, the term "aligned" or "aligned" means that a suitable alignment or position is achieved by interaction with another material, compound, or structure. For example, a portion of the partially aligned photochromic-dichroic compound and/or dichroic compound that is at least partially aligned by interaction with the alignment layer may be at least partially aligned such that the longitudinal axis of the photochromic-dichroic compound and/or dichroic compound in the activated state is substantially parallel to the first general direction of the alignment layer. In addition, a partially aligned photochromic-dichroic compound and/or a portion of a dichroic compound that is at least partially aligned by interaction with the alignment layer may be bonded to or react with a portion of the alignment layer. As used herein with respect to ordering or alignment of materials or structures, the term "general direction" refers to the predominant arrangement or orientation of a material, compound, or structure. In addition, one skilled in the art will recognize that a material, compound, or structure may have a general orientation, although some variation may exist in the arrangement of materials, compounds, or structures provided that the material, compound, or structure has at least one predominant arrangement.

Examples of alignment layers include at least partial coatings comprising at least partially ordered alignment media, at least partially ordered polymeric sheets, at least partially treated surfaces, Langmuir-Blodgett films, and combinations thereof.

The alignment layer may comprise a coating layer comprising an at least partially ordered alignment medium. Examples of suitable alignment media that may be used include photo-alignment materials, rubbing-alignment materials and liquid crystal materials. A method of ordering at least a portion of the alignment medium is described in detail herein below.

As discussed above, the alignment medium may be a liquid crystal material. Liquid crystal materials are generally capable of being ordered or aligned, due to their structure, to adopt a general direction. More specifically, because the liquid crystal molecules have a rod-like or disk-like structure, a rigid longitudinal axis, and a strong dipole, the liquid crystal molecules may be ordered or aligned by interaction with an external force or another structure such that the longitudinal axes of the molecules adopt an orientation generally parallel to the common axis. For example, the molecules of the liquid crystal material may be aligned by using a magnetic field, an electric field, linearly polarized infrared radiation, linearly polarized ultraviolet radiation, linearly polarized visible radiation, or shear forces. The liquid crystal molecules may also be aligned with the oriented surface. That is, the liquid crystal molecules may be applied to an already oriented surface, for example by rubbing, slotting or photo-alignment methods, and subsequently aligned such that the longitudinal axis of each liquid crystal molecule adopts an orientation that is substantially parallel to the general direction of orientation of the surface. Examples of liquid crystal materials suitable for use as alignment media include liquid crystal polymers, liquid crystal prepolymers, liquid crystal monomers, and liquid crystal mesogens. As used herein, the term "prepolymer" means a partially polymerized material.

Liquid crystal monomers suitable for use in the present invention include monofunctional as well as multifunctional liquid crystal monomers. In addition, the liquid crystal monomer may be a crosslinkable liquid crystal monomer and may additionally be a photo-crosslinkable liquid crystal monomer. As used herein, the term "photocrosslinkable" means a material, such as a monomer, prepolymer, or polymer, that can be crosslinked upon exposure to actinic radiation. For example, photo-crosslinkable liquid crystal monomers include those that are crosslinkable upon exposure to ultraviolet radiation and/or visible radiation with or without the use of a polymerization initiator.

Examples of crosslinkable liquid crystalline monomers suitable for use in the present invention include liquid crystalline monomers having functional groups selected from: acrylates, methacrylates, allyl ether, alkynes, amino, anhydrides, epoxides, hydroxides, isocyanates, blocked isocyanates, siloxanes, thiocyanates, thiols, ureas, vinyl ether, and blends thereof. Examples of photo-crosslinkable liquid crystal monomers suitable for use in the coating layer of the alignment layer include liquid crystal monomers having a functional group selected from the group consisting of: acrylates, methacrylates, alkynes, epoxides, thiols, and blends thereof.

Liquid crystal polymers and prepolymers suitable for use in the present invention include main chain liquid crystal polymers and prepolymers in which rod-like or discotic liquid crystal mesogens reside primarily within the polymer backbone, and side chain liquid crystal polymers and prepolymers. In side chain polymers and prepolymers, the rod-like or discotic liquid crystalline mesogens are mainly located in the side chains of the polymer. In addition, the liquid crystalline polymer or prepolymer may be crosslinkable and may additionally be photocrosslinkable.

Examples of liquid crystalline polymers and prepolymers suitable for use in the present invention include, but are not limited to, backbone and side chain polymers and prepolymers having functional groups selected from the group consisting of: acrylates, methacrylates, allyl ether, alkynes, amino, anhydrides, epoxides, hydroxides, isocyanates, blocked isocyanates, siloxanes, thiocyanates, thiols, ureas, vinyl ether, and blends thereof. Examples of photo-crosslinkable liquid crystalline polymers and prepolymers suitable for use in the coating of the alignment layer include those having functional groups selected from the group consisting of: acrylates, methacrylates, alkynes, epoxides, thiols, and blends thereof.

Liquid crystal mesogens suitable for use in the present invention include thermotropic liquid crystal mesogens and lyotropic liquid crystal mesogens. In addition, examples of liquid crystal mesogens suitable for use in the present invention include columnar (or rod-like) liquid crystal mesogens and discotic (or discotic) liquid crystal mesogens.

Examples of photo-alignment materials suitable for use as alignment media include photo-alignable polymer networks. Specific examples of suitable photo-orientable polymer networks include azobenzene derivatives, cinnamic acid derivatives, coumarin derivatives, ferulic acid derivatives and polyimides. For example, the alignment layer may comprise at least one at least partial coating comprising an at least partially ordered photo-orientable polymer network selected from azobenzene derivatives, cinnamic acid derivatives, coumarin derivatives, ferulic acid derivatives and polyimides. Specific examples of cinnamic acid derivatives that can be used as alignment media include polyvinyl alcohol cinnamate and polyvinyl esters of p-methoxycinnamic acid.

As used herein, the term "frictionally oriented material" means a material that can be at least partially ordered by rubbing at least a portion of the material's surface with another suitably textured material. For example, although not limited herein, the rubbed alignment material may be rubbed with a suitably textured cloth or velour (velvet) brush. Examples of rubbing alignment materials suitable for use as alignment media include (poly) imides, (poly) siloxanes, (poly) acrylates, and (poly) coumarins. Thus, for example, although not limited herein, a coating comprising an alignment medium can be a coating comprising a polyimide that has been rubbed with a velvet or cloth to at least partially order at least a portion of the surface of the polyimide.

As discussed above, the at least partially ordered alignment layer may comprise at least partially ordered polymer sheets. For example, although not limited herein, the sheet of polyvinyl alcohol may be a sheet of polyvinyl alcohol that is at least partially ordered by stretching the sheet, after which the sheet may be bonded to at least a portion of a surface of a substrate to form an alignment layer. Alternatively, the ordered polymer sheet may be made by a method of at least partially ordering polymer chains during manufacture, such as, but not limited to, by extrusion. In addition, an at least partially ordered polymeric sheet can be formed by casting or otherwise forming a sheet of liquid crystal material and then at least partially ordering the sheet, for example, but exposing the sheet to at least one of a magnetic field, an electric field, or a shear force. Still further, photo-orientation processes can be used to produce at least partially ordered polymer sheets. For example and without limitation, a sheet of photo-oriented material may be formed, such as by casting, and then at least partially ordered by exposure to linearly polarized ultraviolet radiation. Still other methods of forming at least partially ordered polymer sheets are described herein below.

Still further, the alignment layer may comprise an at least partially treated surface. As used herein, the term "treated surface" refers to at least a portion of a surface that has been physically altered to produce at least one ordered region on at least a portion of the surface. Examples of at least partially treated surfaces include at least partially rubbed surfaces, at least partially etched surfaces, and at least partially embossed surfaces. In addition, the at least partially treated surface may be patterned, for example, using photolithography or interference imaging (interferometric). Examples of at least partially treated surfaces include chemically etched surfaces, plasma etched surfaces, nano-etched surfaces (e.g., surfaces etched using a scanning tunneling microscope or atomic force microscope), laser etched surfaces, and electron beam etched surfaces.

The alignment layer may also include an at least partially treated surface formed by depositing a metal salt (such as a metal oxide or metal fluoride) onto at least a portion of the surface, followed by etching the deposit to form the at least partially treated surface. Examples of suitable techniques for depositing the metal salt include plasma vapor deposition, chemical vapor deposition, and sputtering. Examples of etching methods are described above.

As used herein, the term "Langmuir-Blodgett film" means one or more at least partially ordered molecular films on a surface. For example, although not limited herein, the Langmuir-Blodgett film may be formed by: the substrate is immersed one or more times in the liquid to at least partially cover it with the molecular film, and then the substrate is removed from the liquid so that the molecules of the molecular film are at least partially ordered in the general direction due to the opposing surface tension of the liquid and the substrate. As used herein, the term "molecular film" refers to monomolecular films (i.e., monolayers) as well as films comprising more than one monolayer.

Additionally, the sheet and/or coating may additionally comprise at least one additive that may facilitate one or more of the processing, properties, or properties of the film or coating. Examples of such additives include dyes, alignment promoters, kinetic enhancing additives, photoinitiators, thermal initiators, polymerization inhibitors, solvents, light stabilizers (such as, but not limited to, ultraviolet light absorbers and light stabilizers, such as Hindered Amine Light Stabilizers (HALS)), thermal stabilizers, mold release agents, rheology control agents, leveling agents (such as, but not limited to, surfactants), free radical scavengers, self-assembling materials, gelling agents, and adhesion promoters (such as hexanediol diacrylate and coupling agents). These materials are known to those skilled in the art.

Still further, the sheet or coating may comprise at least one conventional photochromic compound. As used herein, the term "conventional photochromic compound" includes thermally reversible and non-thermally reversible (or photo-reversible) photochromic compounds and excludes photochromic-dichroic compounds.

The display element according to the present invention may optionally further comprise at least one further coating selected from conventional photochromic coatings, antireflective coatings, linearly polarizing coatings, circularly polarizing coatings, elliptically polarizing coatings, transitional coatings, primer layers and protective coatings, such as antifogging coatings, oxygen barrier coatings and ultraviolet absorbing coatings, attached to at least a portion of the substrate. As used herein, the term "transitional coating" means a coating that assists in establishing a gradient in properties between two coatings. For example, although not limited herein, a transitional coating may assist in establishing a gradient in hardness between a relatively hard coating and a relatively soft coating. Examples of transitional coatings include radiation-cured acrylate-based films.

In addition to the alignment layers described above, the display element according to the present invention may additionally comprise at least one coating layer comprising an at least partially ordered alignment transfer material interposed between the alignment layer and the photochromic-dichroic compound and/or dichroic compound (or a film or coating comprising same). Still further, the display element may comprise a plurality of coatings comprising an alignment transfer agent interposed between the alignment layer and the photochromic-dichroic compound. For example, although not limited herein, a display element can include at least one alignment layer comprising a coating comprising an at least partially ordered alignment medium attached to a substrate and a coating comprising an at least partially ordered alignment transfer material attached to the alignment layer. In addition, the photochromic-dichroic compound and/or dichroic compound can be at least partially aligned by interaction with the alignment-transfer material. Examples of alignment transfer materials suitable for use in display elements include, without limitation, those liquid crystal materials described above with respect to the alignment media disclosed herein.

Although not limited herein, the alignment layer can have a thickness that varies widely depending on the end application and/or processing equipment used, for example, at least 0.5 nm to 10,000 nm, such as 0.5 to 1,000 nm, such as 2 to 500 nm, such as 100 to 500 nm.

The sheet or coating comprising the alignment transfer material may have a thickness that varies widely depending on the end application and/or the processing equipment used, for example from 0.5 microns to 1000 microns, such as from 1 to 25 microns, such as from 5 to 20 microns.

The sheet or coating comprising the photochromic-dichroic compound and/or dichroic compound can have a thickness that varies widely depending on the end application and/or processing equipment used, for example, from 0.5 microns to 1,000 microns, such as from 1 to 25 microns, such as from 5 to 20 microns.

The display element of the invention may additionally comprise a birefringent layer. The birefringent layer is operable to transmit radiation with circular or elliptical polarization. When a circular polarizing element is desired, the birefringent layer comprises quarter-glass. The birefringent layer (also referred to as a compensation plate or layer or a retardation plate or layer) may consist of one sheet or may be a multilayer structure of two or more.

The birefringent layer may comprise a layer having a first ordered region having a first general direction and at least one second ordered region adjacent the first ordered region having a second general direction that is the same or different from the first general direction to form a desired pattern in the layer.

The material used to prepare the birefringent layer is not particularly limited and may be any birefringent material known in the art. For example, a polymer film, a liquid crystal film, a self-assembled material, or a film in which a liquid crystal material is aligned may be used. Examples of particular birefringent layers include those described in U.S. patent No. 6,864,932, column 3, line 60 to column 4, line 64; U.S. patent No. 5,550,661, column 4, line 30 to column 7, line 2; U.S. Pat. No. 5,948,487 is those in column 7, line 1 to column 10, line 10, each of which is incorporated herein by reference.

Examples of specific birefringent films include the film model NRF-140, a positively birefringent uniaxial film available from Nitto corporation, japan or Nitto Denko America, inc. Also suitable is an OPTIGRAFIX circular polarizer film available from GRAFIX Plastics, a subsidiary of GRAFIX, inc.

Specific polymer sheets for preparing the birefringent layer may include polyacrylate, polymethacrylate, polymethacrylic acid (C)₁-C₁₂) Alkyl esters, poly (alkylene methacrylates), poly (alkoxylated phenol methacrylates), cellulose acetate, cellulose triacetate, cellulose acetate propionate, cellulose acetate butyrate, poly (vinyl acetate), poly (vinyl alcohol), poly (vinyl chloride), poly (vinylidene chloride),Poly (vinyl pyrrolidone), poly ((meth) acrylamide), poly (dimethylacrylamide), poly (hydroxyethyl methacrylate), poly ((meth) acrylic acid), thermoplastic polycarbonate, polyester, polyurethane, polythiourethane, poly (ethylene terephthalate), polystyrene, poly (α -methylstyrene), copoly (styrene-methyl methacrylate), copoly (styrene-acrylonitrile), polyvinyl butyral, and polymers of the group consisting of polyol (allyl carbonate) monomers, monofunctional acrylate monomers, monofunctional methacrylate monomers, polyfunctional acrylate monomers, polyfunctional methacrylate monomers, diethylene glycol dimethacrylate monomers, diisopropenyl benzene monomers, alkoxylated polyol monomers, and dialkylenepentaerythritol monomers, and in particular self-assembling materials, polycarbonates, polyamides, polyimides, poly (meth) acrylates, polycycloolefins, polyurethanes, poly (urea) urethanes, polythiourethanes, polythiourethane, polythiourea) urethanes, polyallyl (allyl carbonate), cellulose acetate, cellulose diacetate, cellulose triacetate, cellulose propionate, cellulose acetate butyrate, cellulose acetate, polyalkylene-vinyl acetate, polyalkylene-co-acrylates, polyvinyl chloride, and the like.

The birefringent layer may be incorporated into the display element in such a way that the slow axis direction (the direction in which the in-plane refractive index is the largest) of the birefringent layer is oriented with respect to the alignment direction of the polarizer to produce the desired resultant polarization, i.e., circular or elliptical polarization. For example, the quarter-slide will be oriented at an angle of 45 ° +/-5 °, such as 45 ° +/-3 °, with respect to the alignment direction of the polarization produced by the photochromic-dichroic compounds and/or dichroic compounds.

Alternatively, the resulting polarization of the display element may be determined by setting the thickness of the birefringent layer. For example, to produce a circular polarizing element, the thickness of the birefringent layer is such that the exiting refracted rays are out of phase by a quarter wavelength.

According to the present invention, a method of manufacturing a display element is also disclosed. A method of making a display element can include forming a coating comprising at least partially aligned photochromic-dichroic compounds and/or dichroic compounds on a substrate or film. A method of making a display element can include forming a first coating layer comprising at least partially aligned photochromic-dichroic compounds and forming a second coating layer comprising at least partially aligned dichroic compounds on a substrate or film. A method of making a display element can include forming a first coating layer comprising an at least partially aligned dichroic compound and forming a second coating layer comprising an at least partially aligned photochromic-dichroic compound on a substrate or film.

In accordance with the present invention, forming a coating comprising a photochromic-dichroic compound and/or dichroic compound can comprise applying the photochromic-dichroic compound and/or dichroic compound and an anisotropic material to a substrate or film, at least partially ordering the anisotropic material, and at least partially aligning the photochromic-dichroic compound and/or dichroic compound with the anisotropic material. Methods of applying photochromic-dichroic compounds and/or dichroic compounds and anisotropic materials to a substrate or film that can be used in conjunction with the methods of the present invention include, but are not limited to, spin coating, spray coating and spin coating, curtain coating, flow coating, dip coating, injection molding, casting, roll coating, wire coating, and overmolding (overmolding).

According to the present invention, applying the photochromic-dichroic compound and the anisotropic material to the substrate may comprise forming a coating of the anisotropic material on the mold, which may be treated with a release material. The anisotropic material may then be at least partially ordered (as discussed in more detail below) and at least partially solidified. Thereafter, the substrate may be formed over the coating (i.e., overmolded), such as by casting the material forming the substrate in a mold. The material forming the substrate may then be at least partially solidified to form the substrate. Subsequently, the substrate and the coating of anisotropic material may be released from the mold. In addition, the photochromic-dichroic compound may be applied to the mold with the anisotropic material, or may be imbibed into the anisotropic material after the anisotropic material has been applied to the mold, after the anisotropic material has been at least partially ordered, or after the substrate having a coating of the ordered anisotropic material has been released from the mold.

In accordance with the present invention, forming a coating comprising a photochromic-dichroic compound and/or dichroic compound can include applying an anisotropic material to a substrate or film, imbibing the photochromic-dichroic compound and/or dichroic compound into the anisotropic material, at least partially ordering the anisotropic material, and at least partially aligning the photochromic-dichroic compound and/or dichroic compound with the anisotropic material. The method of imbibing the photochromic-dichroic compound into the various coatings is described in more detail herein below.

A method of ordering an anisotropic material includes exposing the anisotropic material to at least one of a magnetic field, an electric field, linearly polarized ultraviolet radiation, linearly polarized infrared radiation, linearly polarized visible radiation, and shear force. In addition, the anisotropic material may be at least partially ordered by aligning the anisotropic material with another material or structure. For example, although not limited herein, the anisotropic material may be at least partially ordered by aligning the anisotropic material with alignment layers, such as but not limited to those previously discussed.

As discussed above, the photochromic-dichroic compounds and/or dichroic compounds contained within or otherwise attached to the anisotropic material can be at least partially aligned by ordering at least a portion of the anisotropic material. In addition, the application of the photochromic-dichroic compound and/or dichroic compound and anisotropic material to the substrate can occur substantially simultaneously, prior to, or after ordering the anisotropic material and/or aligning the photochromic-dichroic compound and/or dichroic compound.

Applying the coating material may include spin coating a solution or mixture of the photochromic-dichroic compound and/or dichroic compound and the anisotropic material (optionally in a solvent or carrier) onto the substrate. The anisotropic material may then be at least partially ordered, for example, by exposing the anisotropic material to a magnetic field, an electric field, linearly polarized ultraviolet radiation, linearly polarized infrared radiation, linearly polarized visible radiation, or shear forces. In addition, the anisotropic material may be at least partially ordered by aligning it with another material or structure, such as an alignment layer.

In accordance with the present invention, a solution or mixture of photochromic-dichroic compounds and/or dichroic compounds and anisotropic materials (optionally in a solvent or carrier) can be applied to the ordered polymer sheet to form a coating. Thereafter, the anisotropic material may be aligned with the polymer sheet. The polymer sheet may then be applied to a substrate by, for example, but not limited to, lamination or bonding. Alternatively, the coating may be transferred from the polymer sheet to the substrate by methods known in the art, such as, but not limited to, hot stamping.

According to the present invention, applying the photochromic-dichroic compound and/or dichroic compound and the anisotropic material to the substrate may comprise applying a phase-separated polymer system comprising a matrix phase forming material comprising a liquid crystal material and a guest phase forming material comprising an anisotropic material and the photochromic-dichroic compound and/or dichroic compound. After application of the phase separated polymer system, the liquid crystal material of the matrix phase and the anisotropic material of the guest phase may be at least partially ordered such that the photochromic-dichroic compounds and/or dichroic compounds are aligned with the anisotropic material of the guest phase. A method of at least partially ordering a matrix phase forming material and a guest phase forming material of a phase separating polymer system includes exposing a coating comprising a phase separating polymer system to at least one of: magnetic fields, electric fields, linearly polarized infrared radiation, linearly polarized ultraviolet radiation, linearly polarized visible radiation, and shear forces. Additionally, at least partially ordering the matrix phase-forming material and the guest phase-forming material may include at least partially aligning the portions with an alignment layer.

After at least partially ordering the matrix phase-forming material and the guest phase-forming material, the guest phase-forming material may be separated from the matrix phase-forming material by polymerization-induced phase separation and/or solvent-induced phase separation. Although for clarity, reference to separation of a material forming the guest phase from a material forming the matrix phase is described herein to separation of a material forming the matrix phase from a material forming the guest phase, it should be appreciated that this language is intended to encompass any separation between materials forming the two phases. That is, the language is intended to encompass both separation of the guest phase-forming material from the matrix phase-forming material and separation of the matrix phase-forming material from the guest phase-forming material, as well as simultaneous separation of the phase-forming materials, and any combination thereof.

The material forming the matrix phase may comprise a liquid crystal material selected from liquid crystal monomers, liquid crystal prepolymers and liquid crystal polymers. In addition, the material forming the guest phase may include a liquid crystal material selected from liquid crystal mesogens, liquid crystal monomers and liquid crystal polymers and prepolymers.

In accordance with the present invention, forming a coating comprising a photochromic-dichroic compound and/or dichroic compound can include applying an anisotropic material to a substrate or film, imbibing the photochromic-dichroic compound and/or dichroic compound into the anisotropic material, at least partially ordering the anisotropic material, and at least partially aligning the photochromic-dichroic compound and/or dichroic compound with the anisotropic material. Additionally, at least partially ordering the anisotropic material can occur prior to imbibing the photochromic-dichroic compound and/or dichroic compound therein.

For example, the photochromic-dichroic compound and/or dichroic compound can be imbibed into the anisotropic material, for example, by applying a solution or mixture of the photochromic-dichroic compound and/or dichroic compound in a carrier to a portion of the anisotropic material and allowing the photochromic-dichroic compound and/or dichroic compound to diffuse into the anisotropic material (with or without heat). In addition, the anisotropic material may be part of a phase separated polymer coating as described above.

The method of making a display element can further include imparting at least one alignment layer to the substrate, subsequently forming a coating comprising an at least partially aligned photochromic-dichroic compound on the alignment layer, imparting at least one alignment layer on the formed coating, and subsequently forming a coating comprising an at least partially aligned dichroic compound on the alignment layer. Imparting an alignment layer to the substrate may include at least one of: forming a coating comprising an at least partially ordered alignment medium on a substrate, applying an at least partially ordered polymer sheet to the substrate, treating the substrate, and forming a Langmuir-Blodgett film on the substrate.

Although not required, imparting an alignment layer may include forming a coating of an at least partially ordered alignment medium, which may be at least partially solidified. In addition, solidifying the alignment medium may occur substantially simultaneously with aligning the alignment medium or it may occur after aligning the alignment medium. Still further, solidifying the alignment medium may comprise at least partially curing the medium by exposing it to infrared, ultraviolet, gamma ray, microwave, or electron radiation to initiate polymerization or crosslinking of the polymerizable components in the presence or absence of a catalyst or initiator. This may be followed by a heating step if desired or required.

As discussed above, after the alignment layer is imparted on the substrate, a coating comprising at least partially aligned photochromic-dichroic compounds and/or dichroic compounds can be formed on the alignment layer.

In addition, as discussed above with respect to coatings comprising interpenetrating polymer networks, the polymerizable composition can be an isotropic material or an anisotropic material, provided that the coating comprising the photochromic-dichroic compound and/or dichroic compound is anisotropic as a whole.

According to the present invention, forming the sheet may comprise applying a phase separated polymer system comprising a matrix phase forming material comprising a liquid crystal material and a guest phase forming material comprising a liquid crystal material and at least one photochromic-dichroic compound and/or dichroic compound onto the substrate. Thereafter, the matrix phase-forming material and the guest phase-forming material may be at least partially ordered and the photochromic-dichroic compounds and/or dichroic compounds may be at least partially aligned with the guest phase-forming material. After alignment, the guest phase forming material may be separated from the matrix phase forming material by polymerization-induced phase separation and/or solvent-induced phase separation, and the phase separated polymer coating may be removed from the substrate to form a sheet.

Alternatively, as discussed above, the phase separating polymer system may be applied on a substrate, ordered and aligned, and then removed from the substrate to form a phase separated polymer sheet. Subsequently, the photochromic-dichroic compound and/or dichroic compound can be imbibed into the sheet. Alternatively or additionally, the photochromic-dichroic compound and/or dichroic compound can be imbibed into the coating, which is then removed from the substrate to form the sheet.

In accordance with the present invention, forming the sheet can include forming an at least partially ordered liquid crystal polymer sheet and imbibing a liquid crystal mesogen and a photochromic-dichroic compound and/or dichroic compound into the liquid crystal polymer sheet. For example, a sheet comprising a liquid crystalline polymer may be formed and at least partially ordered by a method of forming a polymer sheet that at least partially orders the liquid crystalline polymer during forming, for example by extrusion. Alternatively, the liquid crystal polymer may be cast onto a substrate and at least partially ordered by one of the methods of ordering liquid crystal materials set forth above. For example, although not limited herein, the liquid crystal material may be exposed to a magnetic or electric field. After at least partial ordering, the liquid crystal polymer can be at least partially solidified and removed from the substrate to form a sheet comprising an at least partially ordered liquid crystal polymer matrix. Still further, the liquid crystal polymer sheet can be cast, at least partially solidified, and subsequently stretched to form a sheet comprising an at least partially ordered liquid crystal polymer.

After forming the sheet comprising the at least partially ordered liquid crystal polymer, the liquid crystal mesogen and the photochromic-dichroic compound and/or dichroic compound may be imbibed into the liquid crystal polymer matrix. For example, although not limited herein, the liquid crystal mesogen and photochromic-dichroic compounds and/or dichroic compounds may be imbibed into the liquid crystal polymer by: a solution or mixture of liquid crystal mesogen and photochromic-dichroic compounds and/or dichroic compounds in a carrier is applied to a liquid crystal polymer, and then the liquid crystal mesogen and photochromic-dichroic compounds and/or dichroic compounds are diffused into the liquid crystal polymer sheet (with or without heating). Alternatively, the sheet comprising the liquid crystalline polymer may be immersed in a solution or mixture of liquid crystalline mesogen and photochromic-dichroic compounds and/or dichroic compounds in a carrier, and the liquid crystalline mesogen and photochromic-dichroic compounds and/or dichroic compounds may be imbibed into the liquid crystalline polymer sheet by diffusion (with or without heating).

In accordance with the present invention, forming the sheet can include forming a liquid crystal polymer sheet, imbibing a liquid crystal mesogen and a photochromic-dichroic compound and/or dichroic compound (e.g., as discussed above) into the liquid crystal polymer sheet, and thereafter at least partially ordering the liquid crystal polymer, the liquid crystal mesogen, and the photochromic-dichroic compound and/or dichroic compound distributed therein. Although not limited herein, the liquid crystal polymer sheet, the liquid crystal mesogen, and the photochromic-dichroic compound and/or dichroic compound distributed therein may be at least partially ordered, for example, by stretching the liquid crystal polymer sheet. In addition, the liquid crystalline polymer sheet can be formed using conventional polymer processing techniques, such as, but not limited to, extrusion and casting.

According to the present invention, a photo-oriented polymer sheet comprising an anisotropic material and a coating of a photochromic-dichroic compound and/or dichroic compound may be applied to a substrate. For example, a photo-oriented polymer sheet can be formed by: applying a layer of photo-orientable polymer network on a release layer and subsequently ordering and at least partially curing the photo-orientable polymer network; forming a coating of an anisotropic material and a photochromic-dichroic compound and/or dichroic compound on the layer comprising the photo-orientable polymer network, at least partially aligning the anisotropic material and the photochromic-dichroic compound and/or dichroic compound with the photo-orientable polymer network, and curing the anisotropic material. The release layer can then be removed and the layer of photo-orientable polymer network including the coating of anisotropic material and photochromic-dichroic compound removed from the release layer to form an ordered polymer sheet.

Additionally attaching the polymeric sheet comprising the photochromic-dichroic compound and/or dichroic compound to the substrate can include, for example, at least one of: lamination, fusing, in-mold casting, and bonding of the polymer sheet to the substrate. As used herein, in-die casting includes various casting techniques, such as, but not limited to: overmolding, where the sheet is placed in a mold and a substrate is formed over at least a portion of the sheet (e.g., by casting); and injection molding, wherein the substrate is formed around the sheet.

As discussed above, the display element may optionally comprise a birefringent layer. The birefringent layer may be applied by, for example, lamination or adhesive bonding. Alternatively, the birefringent layer may be applied by methods known in the art, such as hot stamping. Suitable adhesives for joining the birefringent layers include those disclosed in U.S. patent No. 6,864,932, column 4, line 65 to column 60, incorporated herein by reference.

As discussed previously, the present invention relates to display elements and devices. Additionally, as discussed above, the term "display" as used herein means a visual representation of information in the form of words, numbers, symbols, designs, or drawings. Examples of display devices include screens and monitors.

The display device of the present invention includes the above-described display element. The display device may include an Organic Light Emitting Diode (OLED), a Light Emitting Diode (LED), a Liquid Crystal Display (LCD), a Plasma Display Panel (PDP), an electroluminescent display (ELD), or a Cathode Ray Tube (CRT).

The display device may comprise a light emitting source, such as a light emitting layer, and the display element of the present invention. The display device may optionally additionally include a reflective backing layer that helps direct radiation generated by the light-emitting source out of the display device through the display element. The display element includes at least one layer comprising a photochromic-dichroic compound, or combination thereof. The display device may additionally comprise a birefringent layer. The birefringent layer may comprise a quarter-wave slide (also known as a quarter-wave retarder).

The light generated by the light emitting source may be referred to as display light. The dichroic compound and/or photochromic-dichroic compound of the display element will linearly polarize and absorb a portion of the display light as it passes through the display element. As discussed above, the display element will transmit radiation at different percentages (% T) in the first state and the second state of the display element.

In addition to display light, ambient or environmental light may be transmitted through the display element into the display device. When ambient or ambient light passes through the display element, at least a portion of the light is linearly polarized and/or absorbed by the dichroic compound and/or the photochromic/dichroic compound. After passing through one or more layers containing photochromic-dichroic compounds and/or dichroic compounds, ambient or ambient light can pass through a birefringent layer (e.g., a quarter-glass) that converts linearly polarized light to circularly polarized light. The axis of the quarter-slide can be oriented at 45 degrees with respect to the axis of the one or more linear polarizing layers comprising the photochromic-dichroic compound and/or dichroic compound. Thus, when ambient or ambient linearly polarized light passes through the quarter-glass, it is converted to circularly polarized light. At least a portion of the circularly polarized light can pass through the light emitting source and can be reflected by the reflective backing layer, wherein the circularly polarized light travels in opposite directions (e.g., from right-handed circularly polarized to left-handed circularly polarized light). The reflected circularly polarized light can then pass through the light emitting source back into the quarter-slide. When the circularly polarized light passes through the quarter-glass for a second time, it is converted to linearly polarized light, the plane of polarization of which is rotated 90 degrees relative to the original direction of the linearly polarized ambient or environmental light, and the linear polarizing layer or layers containing the photochromic-dichroic compounds and/or dichroic compounds effectively absorb or block the return reflected light from being transmitted back through the display element. Thus, the intensity of the resulting reflected light is reduced compared to the initial intensity of ambient or ambient light passing through the display element of the present invention. Ambient or ambient light is directed towards the display device from many different angles of incidence and not every angle of ambient or ambient light will pass through the display element in this way. However, the transmittance of the reflected light through the display element is reduced compared to the transmittance of light generated from the light emission source that passes through the display element only once. This results in improved readability of the display device in bright or sunny conditions.

Further, as discussed above, the percent transmittance of the display element varies. For example, in the first state, most, if not all, of the photochromic-dichroic compound is unactivated and does not linearly polarize or absorb radiation. Thus, any linearly polarized or absorbed radiation is provided by the dichroic compound, and a larger percentage of the radiation is transmitted by the display element. Upon activation of the photochromic-dichroic compound, the photochromic-dichroic compound linearly polarizes and absorbs radiation. Thus enhancing the linear polarization and absorption of radiation and the display element transmits a reduced percentage of radiation compared to the first state. Suitable transmission percentages for the first and second states of the display element are discussed above.

For purposes of this detailed description, unless explicitly stated to the contrary herein, it is to be understood that the invention may assume various alternative variations and step sequences. Moreover, except in any operating examples or otherwise indicated, all numbers (such as those expressing values, amounts, percentages, ranges, subranges, and fractions) may be read as if prefaced by the word "about", even if the term does not expressly appear. Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Where a closed or open numerical range is described herein, all numbers, values, amounts, percentages, sub-ranges and fractions within or encompassed by that numerical range are to be considered specifically encompassed within and within the original disclosure of the application as if those numbers, values, amounts, percentages, sub-ranges and fractions were expressly written herein in their entirety.

Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

As used herein, unless otherwise indicated, plural terms may encompass their singular counterparts and vice versa unless otherwise indicated. For example, although reference is made herein to "a" photochromic-dichroic compound, "a" substrate, "a" sheet, and "a" coating/paint, combinations of these components (i.e., a plurality/plurality of these components) may be used. In addition, in this application, the use of "or" means "and/or" unless specifically stated otherwise, although "and/or" may be explicitly used in certain circumstances.

As used herein, "comprising," "including," and similar terms, are understood in the context of this application to be synonymous with "comprising," and are thus open-ended and do not preclude the presence of additional unrecited or unrecited elements, materials, ingredients, or method steps. As used herein, "consisting of …" is understood in the context of this application to exclude the presence of any unspecified element, ingredient or method step. As used herein, "consisting essentially of …" is understood in the context of this application to include the named elements, materials, ingredients, or method steps "as well as those that do not materially affect the basic and novel characteristics described.

As used herein, the terms "on …", "onto …", "applied on …", "applied on …", "formed on …", "deposited on …", "deposited on …" mean formed, overlaid, deposited, or provided on a surface but not necessarily in contact with the surface. For example, a coating "deposited onto a substrate" does not preclude the presence of one or more other intermediate coating layers of the same or different composition located between the coating and the substrate.

While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the claims appended and any and all equivalents thereof.

Aspect(s)

The invention thus relates in particular to the following non-limiting aspects 1 to 17:

1. a display element comprising a photochromic-dichroic compound and a dichroic compound, the display element having a first absorption state and a second absorption state and being operable to switch from the first absorption state to the second absorption state in response to actinic radiation and to switch back to the first absorption state in response to actinic radiation and/or thermal energy, wherein the first absorption state has a percent transmission of from 50% to 80% and the second absorption state has a percent transmission of from 10% to 50%.

2. The display element according to aspect 1, wherein the first absorption state has a percent transmission of 60% to 70%, and the second absorption state has a percent transmission of 15% to 40%.

3. The display element according to aspect 1 or aspect 2, wherein the first absorption state has a linear polarization efficiency of 5% to 70%, and the second absorption state has a linear polarization efficiency of 50% to 99.9%.

4. The display element according to any one of the preceding aspects, wherein the photochromic-dichroic compound comprises a pyran photochromic group, wherein the pyran photochromic group preferably comprises a naphthopyran.

5. The display element according to any one of the preceding aspects, wherein the dichroic compound comprises an anthraquinone dye, an azo dye, or a combination thereof.

6. The display element according to any one of the preceding aspects, wherein the display element comprises a sheet comprising the photochromic-dichroic compound and the dichroic compound or comprises a first sheet comprising the photochromic-dichroic compound and a second sheet comprising the dichroic compound.

7. The display element according to any one of the preceding aspects, further comprising a substrate.

8. The display element according to aspect 7, further comprising a coating layer coupled to the substrate, the coating layer comprising a photochromic-dichroic compound and a dichroic compound, wherein the coating layer preferably comprises at least one self-assembling material, such as self-assembling materials including liquid crystal materials, block copolymers, and combinations thereof.

9. The display element according to aspect 7, further comprising an alignment layer, e.g. an alignment layer comprising a photoalignment layer, and a coating comprising a photochromic-dichroic compound and a dichroic compound, wherein the coating is attached to the alignment layer.

10. The display element of aspect 7, further comprising a first coating layer coupled to the substrate, the first coating layer comprising a photochromic-dichroic compound, and a second coating layer coupled to the substrate, the second coating layer comprising a dichroic compound.

11. A display element according to any one of the preceding aspects, additionally comprising a birefringent layer, wherein the birefringent layer preferably comprises a quarter-glass sheet.

12. The display element according to any one of the preceding aspects, wherein the weight ratio of dichroic compound to photochromic-dichroic compound is from 0.005:1 to 0.150: 1.

13. A display device comprising the display element according to any one of the preceding aspects 1 to 12.

14. The display device according to aspect 13, wherein the display device further comprises an organic light emitting diode, a liquid crystal display, a plasma display panel, an electroluminescent display, or a cathode ray tube.

15. The display device according to aspect 13, further comprising:

a light emitting layer;

a reflective backing layer;

a quarter-wave retarder; and

at least one layer comprising a photochromic-dichroic compound, or combination thereof.

16. The display device according to aspect 15, wherein the light emitting layer comprises a light emitting diode or an organic light emitting diode.

17. The display device according to any of aspects 15 or 16, wherein the display device comprises a first layer and a second layer, wherein the first layer comprises a photochromic-dichroic compound and the second layer comprises a dichroic compound, wherein preferably a quarter-wave retarder is attached to the first layer, and the first layer is attached to the second layer.

The following examples illustrate the invention, but are not to be construed as limiting the invention to the details thereof. Unless otherwise indicated, all parts and percentages in the following examples, as well as throughout the specification, are by weight.

Examples

Example A liquid Crystal coating compositions and formulations

Liquid crystal monomer composition

The following liquid crystal monomer ("LCM") compositions were prepared:

LCM-1 is 1- (6- (8- (4- (4- (8-acryloyloxyhexyl) oxy) benzoyloxy) phenoxycarbonyl) phenoxy) octyloxy) -6-oxohexyloxy) -6-oxohex-1-ol, prepared according to the procedure described in example 17 of U.S. Pat. No. 7,910,019, the disclosure of which is incorporated herein by reference.

LCM-2 is commercially available RM257, reported as 4- (3-Acryloyloxypropoxy) -benzoic acid 2-methyl-1, 4-phenylene ester, available from EMD Chemicals, Inc., of formula C₃₃H₃₂O₁₀。

LCM-3 is 1- (6- (4- (4- (trans-4-pentylcyclohexyl) phenoxycarbonyl) phenoxy) hexyloxy) -2-methylpropan-2-en-1-one, prepared according to the procedure of example 1 in U.S. patent No. 7,910,019, except that n is 0, the disclosure of which is incorporated herein by reference.

LCM-4 is 1- (6- (6- (6- (6- (6- (6- (8- (4- (4- (4-hexyloxybenzoyloxy) phenoxycarbonyl) -phenoxy) octyloxy) -6-oxohexyloxy) -2-methylpropan-2-en-1-one prepared according to the procedure in U.S. Pat. No. 7,910,019, the disclosure of which is incorporated herein by reference.

LCM-5 is commercially available RM105, available from EMD Chemicals, Inc and reported as formula C₂₃H₂₆O₆。

Photochromic-dichroic Grey formulation (Grey-1)

The photochromic-dichroic gray formulation, referred to herein as Grey-1, was prepared by combining the photochromic-dichroic ("PC") dyes listed in table a below.

Table a-Grey-1 photochromic dyes in tinting formulations

Liquid crystal coating formulation ("LCCF")

LCCF-1 was prepared as follows: to a suitable flask containing a mixture of anisole (3.99g) and BYK-322 additive 0.004g (reported as an aralkyl modified polymethylalkylsiloxane, available from BYK Chemie, USA) were added LCM-1(1.08g), LCM-2(2.4g), LCM-3(1.08g), LCM-4(1.44g), Grey-1(0.72g), 4-methoxyphenol (0.006g) and819(0.09g, photoinitiator available from Ciba-Geigy Corporation). Further adding at a molar ratio of 1:4(UV-24: Grey-1)UV-24 (light absorber available from Cytec Industries). The resulting mixture was stirred at 80 ℃ for 2 hours and cooled to about 26 ℃.

LCCF-2 was prepared as follows: to a suitable flask containing a mixture of anisole (3.99g) and BYK-322 additive 0.004g (reported as an aralkyl modified polymethylalkylsiloxane, available from BYK Chemie, USA) was added LCM-2(3.0g), LCM-5(3.0g), the dichroic dye Blue AB2 batch 3 (from Nematol GmbH)&Kg, (0.06g)), dichroic dye Orange AZ01 batch 1 (from Nematel GmbH)&KG, (0.06g)), 4-methoxyphenol (0.06g) and819(0.09g, photoinitiator available from Ciba-Geigy Corporation). The resulting mixture was stirred at 80 ℃ for 2 hours and cooled to about 26 ℃.

LCCF-3 was prepared as follows: to a suitable flask containing a mixture of anisole (3.99g) and BYK-322 additive 0.004g (reported as an aralkyl modified polymethylalkylsiloxane, available from BYK Chemie, USA) was added LCM-1(1.08g), LCM-2(2.4g), LCM-3(1.08g), LCM-4(1.44g), Grey-1(0.72g), the dichroic dye BlueAB2 batch 3 (from Nematol GmbH)&Kg, 0.012g) of the dichroic dye Orange AZ01 batch 1 (from Nematel GmbH)&KG, 0.06g), 4-methoxyphenol (0.006g) and819(0.09g, photoinitiator available from Ciba-Geigy Corporation). Further adding at a molar ratio of 1:4(UV-24: Grey-1)UV-24 (light absorber available from Cytec Industries). Stirring the resulting mixture at 80 deg.CStirred for 2 hours and cooled to about 26 ℃.

Example B preparation of a Photoaligned coating solution

A solution of the photoalignment material poly [ (E) -2-methoxy-4- (3-methoxy-3-oxoprop-1-enyl) phenyl 4- (6- (methacryloyloxy) hexyloxy) benzoate ] was prepared by adding 6 weight percent of the photoalignment material to cyclopentanone, based on the total weight of the solution.

Example C-procedure for preparing and coating a substrate

Substrate

A Corning 2947-75x50mm glass slide on a plate was used as the substrate. The plate has dimensions of 75x50mm and a thickness of 0.96 to 1.06 mm. By using impregnation withEach substrate was cleaned by wiping with a paper towel and dried with an air stream.

Each substrate was corona treated by passing over a conveyor belt in a Tantec EST Systems serial No. 020270Power GeneratorHV 2000 series corona treatment apparatus with a high voltage transformer. The substrate was exposed to a corona generated by 53.99KV,500 volts while traveling on a conveyor at a belt speed of 3 ft/min.

Coating process of optical alignment material

The photoalignment coating solution prepared in example B was applied to a test substrate by spin coating on a portion of the surface of the test substrate by dispensing approximately 1.0mL of the solution and spinning the substrate at 800 revolutions per minute (rpm) for 3 seconds, then 1,000rpm for 7 seconds, then 2500rpm for 4 seconds. A rotary processing machine (WS-400B-6NPP/LITE) from Laurell Technologies Corp. was used for spin coating. Thereafter, the coated substrate was placed in an oven maintained at 120 ℃ for 30 minutes. The coated substrate was cooled to about 26 ℃.

Using a power supply having 400 wattsOf CorpA UVC-6 UV/conveyor system at least partially orders the dried photoalignment layer on each substrate by exposure to linearly polarized ultraviolet radiation. The light source is oriented such that the radiation is linearly polarized in a plane perpendicular to the substrate surface. UV Power Puck from EIT Inc was used^TMA high energy radiometer (serial No. 2066) measures the amount of uv radiation to which each photo-alignment layer is exposed and is as follows: UVA0.126W/cm²And 5.962J/cm²；UVB 0.017W/cm²And 0.078J/cm²；UVC 0W/cm²And 0J/cm²(ii) a And UVV0.046W/cm²And 2.150J/cm². After ordering at least a portion of the photo-orientable polymer network, the substrate is cooled to about 26 ℃ and remains covered.

Coating process of liquid crystal coating preparation

The liquid crystal coating formulations ("LCCF") prepared in example a were each spin coated at 400 revolutions per minute (rpm) for 6 seconds, then 800rpm for 4 seconds, onto an at least partially ordered photoalignment material prepared as described above on a test substrate. Each coated substrate was placed in an oven at 65 ℃ for 30 minutes. The substrates were then cured in a nitrogen atmosphere under two ultraviolet lamps in a UV Curing Oven Machine designed and built by Belcan engineering with a peak intensity of 0.445Watts/cm when run at a rate of 2ft/min on a conveyor belt²UVA and 0.179Watts/cm²UW and UV dose of 2.753 joules/cm²UVA and 1.191 Joule/cm²UW of (2). Using the corona treatment apparatus described above, the cured layer was exposed to a corona generated by 53.00KV,500 watts while traveling on a conveyor at a belt speed of 3 ft/min.

Example 1

Control sample example 1 was coated with the photoalignment layer of example B and the LCCF-1 coating of example a according to the procedure of example C. The display element of example 1 contained a photochromic-dichroic dye, but no fixed-hue dichroic dye. The layer stack configuration is shown in fig. 1.

Practice ofExample 2

Example 2 was coated according to the procedure of example C with the multilayer stack of photoalignment layer/LCCF-2 coating/photoalignment layer/LCCF-1 coating of examples A and B. The display element of example 2 contained both a photochromic-dichroic dye and a dichroic dye. The layer stack configuration is shown in fig. 2.

Example 3

Example 3 was coated according to the procedure of example C with the photoalignment layer of example B and the LCCF-3 coating of example a. The display element of example 3 contained both a photochromic-dichroic dye and a dichroic dye. The layer stack configuration is shown in fig. 3.

Evaluation of display element

And (3) sample testing: when testing the transparent to polarization and transparent to circularly polarized properties, an optical bench was used to measure the optical properties of the display elements and derive the absorbance of each display element. Prior to testing, each sample was exposed to activating radiation (UVA) for 10 minutes at a distance of 15 centimeters (cm) from a bank of four UV tubes BLE-7900B supplied by spectra corp, and then placed at 40 ℃ for 1 hour. Subsequently, the samples were exposed for 1 hour at a distance of 15cm from a stack (a bankof) of four UVIess tubes F4OGO supplied by General Electric and finally kept in the dark for 1 hour. The display element was then placed in a temperature controlled air cell (cell) on the optical bench at (23 ℃. + -. 0.1 ℃). An activating light source (Newport/Oriel model 67005300 watt xenon arc lamp housing, 69911 power supply and 68945 digital exposure controller, equipped with a Uniblitz VS25 (with VMM-D4 shutter driver) high speed computer controlled shutter that is temporarily closed during the data collection process so that stray light does not interfere with the data collection process, a Schott 3mm KG-2 bandpass filter that removes short wavelength radiation, one or more neutral density filters for intensity attenuation and a condenser lens for beam collimation) is directed at the surface on the sample side with an angle of incidence of 30 ° to 35 °.

The broadband light source for monitoring the response measurements is positioned perpendicular to the display element surface. Enhanced signals at shorter visible wavelengths were obtained by collecting and combining separately filtered light from a 100 watt tungsten halogen lamp (controlled by a Lambda UP60-14 constant voltage power supply) with a split-end drop cable. Light from one side of the tungsten halogen lamp was filtered with a Schott KG1 filter to absorb heat and with a Hoya B-440 filter to allow shorter wavelengths to pass. The other side of the light was filtered or unfiltered with a Schott KG1 filter. Light is collected by focusing light from each side of the lamp onto the other end of the bifurcated drop cable and then combined into one light source exiting the single end of the cable. A 4 inch light pipe was attached to a single end of the cable to ensure proper mixing.

The polarization of the light source was achieved by passing the light from a single end of the cable through a Moxtek, Proflux polarizer, which was held in a computer driven motorized rotating platform (model M-061-PD or M-660.55, from Polytech, PI). The monitoring beam is arranged such that one plane of polarization (0) is perpendicular to the plane of the optical bench stage and a second plane of polarization (90) is parallel to the plane of the optical bench stage.

Prior to UV activation, the display elements were aligned as follows. The electrical dark spectrum, the reference spectrum, and the dark spectrum were collected at both 0 and 90 degree polarization directions. Alignment of the polarized samples was done by activating the samples for 15 minutes and then rotating the samples relative to the Moxtek analyzer polarizer until maximum absorbance at 590nm was reached. At this position, the sample is aligned at a 90 degree angle +/-0.25 degrees with the analyzer polarizer. Once aligned, 0/90 degree absorption spectra were collected at 5 second intervals for 120 seconds, then the xenon arc lamp shutter (shutter) was turned off and the sample was bleached, while the Moxtek polarizer continued to rotate and the absorption spectra were collected at 0 and 90 degrees as a function of time.

For transparency to linearity measurements, the display element was exposed to UVA from an activating light source at 6.7W/m2 for 15 minutes to activate the photochromic dichroic dye. An international light research spectral radiometer (ILT950 type) with a detector system (SED033 type detector, B filter and diffuser) was used to verify the exposure at the beginning of the day. Light polarized to the 0 ° polarization plane from the monitoring source was then passed through the coated sample and focused on a 1 inch integrating sphere connected to an Ocean Optics 2000 spectrophotometer using a single function fiber optic cable. After passing through the sample, spectral information was collected using ocean optics spectra suite and PPG proprietary software. While the photochromic-dichroic dye was activated, the position of the Moxtek polarizer was rotated back and forth to polarize the light from the monitoring light source to the 90 ° polarization plane and back. Data was collected at 5 second intervals during activation and every 3 seconds during decay for approximately 15 minutes. For each test, the rotation of the polarizer was adjusted to collect data in the following sequence of planes of polarization: 0 °, 90 °,0 °, etc.

The absorption spectra of each display element were obtained and analyzed using Igor Pro software (available from WaveMetrics). The change in absorbance of each display element in each polarization direction was calculated by subtracting the 0-point (0-time) (i.e., unactivated) absorption measurement of the display element at each test wavelength. Photopic response measurements were collected due to the use of various photochromic-dichroic compounds in the display element. In the photopic region of the activation curve that saturates or approaches the photochromic response of each display element (i.e., the region where the measured absorbance does not increase or does not significantly increase over time), the average absorbance value is obtained by averaging the absorbance at each time interval in that region. For 0 ° and 90 ° polarizations, average absorbance values within a predetermined wavelength range corresponding to λ max-vis +/-5nm are extracted, and the absorbance for each wavelength within that range is calculated by dividing the larger average absorbance by the smaller average absorbance. For each extracted wavelength, 5 to 100 data points were averaged. The average absorbance of the photochromic-dichroic dye is then calculated by averaging the individual absorbances. The average absorbance of the sample is then calculated by averaging these individual absorbances.

The results are reported below, where the first decay half-life ("T1/2") value is the time interval in seconds for the delta OD of the activated form of the photochromic-dichroic dye in the sample to reach half the maximum delta OD at 73.4 ° F (23 ℃) after removal of the activating light source.

The% T value for the gray/brown lens was calculated based on CIE Y transmittance. Initial and final average percent transmittance (% T) values and polarization efficiencies were obtained according to the following equations.

Initial% T ═ (% T parallel +% T crossover)/2 (initial means unactivated)

Final% T ═ (% T parallel +% T crossover)/2 (final meaning complete activation)

% PE 100 ((% T parallel +% T crossover))

The above procedure was run at least twice for each sample. The results of the clear to linear polarization test are presented in table I below.

TABLE I

The transparent to circular polarization study was performed in the same manner as the transparent to linear study except for the modifications described below. The Moxtek polarizer was moved on the PI spin stage to the side opposite the membrane module. For circular polarization measurements to be taken, the circular polarizers need to face each other so that the quarter-wave plates face each other. To align the system, a known melles griot (mg) polarizer was placed in front of the box assembly, oriented at 0 degrees, to transmit the laser light to the maximum (coherent ultra low noise laser diode module-635 nm). The Moxtek polarizer was then rotated on the stage to reach the null. A quarter wave plate (from Melles Griot) was added to the optical path just before the Moxtek polarizer. A quarter wave plate (mounted on a goniometer from Opto-Sigma with its center point of rotation 76mm from the top plate: the assembly is mounted on a 1.5 inch damper rod from melles griot) is rotated to achieve a null signal for the laser. This ensures that the fast or slow axis of the quarter wave plate is aligned with the transmission direction of the Moxtek polarizer.

Next, the Moxtek polarizer was rotated 45 degrees and the MG polarizer was removed. The Moxtek polarizer now bisects the fast and slow axes of the MG quarter wave plate and produces either left-handed or right-handed circularly polarized light. The electrical dark, reference and dark reference spectra of both left-handed or right-handed circularly polarized light were collected by rotating the Moxtek polarizer +/-90 degrees (or from fast to full and then halving the fast and slow axes of the MG quarter wave plate from slow to fast).

With the reference spectra collected, the sample was inserted into a temperature controlled gas cell. The Moxtek polarizer was rotated 45 degrees to horizontal and the MG polarizer (at 0 degrees) was placed in the beam path to create a crossed polarizer configuration. The display element is placed in the beam path and the laser light is directed through crossed polarizers and the sample. Alignment of the polarized samples was done by activating the samples for 15 minutes, then rotating the samples relative to the Moxtek analyzer polarizer until a maximum absorbance of 590nm was reached. In this position, the sample is aligned 90 degrees to +/-0.25 degrees with the analyzer polarizer. Once aligned, 0/90 degree absorption spectra were collected at 5 second intervals for 120 seconds, then the xenon arc lamp mask was turned off, the sample was allowed to decay, while the Moxtek polarizer continued to rotate and the absorption spectra were collected at 0 and 90 degrees as a function of time.

It is noted that for example 2, the poor quality quarter wave plate of the sample (due to refractive index dispersion) requires manual analysis of the data in order to use the correct "cross-polarization" spectra. From the raw data table generated by the optical bench, the bleached CIE Y transmittance (% T) and fully activated transmittance were back-calculated (back calculated) for the bleached optical density at the angle (to +/-2.5 degrees) where the maximum darkness of the cross-polarization was found. This is done because there is some level of angular dependence between crossed circular polarizers due to the poor quality of the quarter-wave plates in the 380 to 780nm range (they are designed for 560 nm).

The data acquisition was performed as before (120 second delay, data collection activation at 5 second intervals for 15 minutes, decay to a second half-life at 3 second intervals for 30 minutes throughout the data collection process, rotation of the Moxtek polarizer +/-90 degrees, since the transmission axis of the Moxtek polarizer bisects the quarter wave plate (MG), then the rotation of the Moxtek polarizer goes from bisecting the fast-slow axis to bisecting the slow-fast axis, which produces right-handed circularly polarized light in one orientation and left-handed circularly polarized light in the other orientation.

The measurement of the coated samples using a quarter wave plate is essentially the same procedure except that the laser intensity is reduced by using 1.0 and 0.5ND filters. The results of the transparent to circular polarization studies are listed below in table 2.

TABLE 2

Those skilled in the art will appreciate that numerous modifications and variations may be made in light of the above disclosure without departing from the broad inventive concept described and illustrated herein. Accordingly, it is understood that the foregoing disclosure is only illustrative of various exemplary aspects of the present application and that numerous modifications and variations within the spirit and scope of the present application and appended claims may be readily made by those skilled in the art.

Claims

2. The display element of claim 1, wherein the first absorption state has a percent transmission of 60% to 70% and the second absorption state has a percent transmission of 15% to 40%.

3. The display element of claim 1, wherein the first absorption state has a linear polarization efficiency of 5% to 70% and the second absorption state has a linear polarization efficiency of 50% to 99.9%.

4. The display element of claim 1, wherein the photochromic-dichroic compound comprises a pyran photochromic group.

5. The display element of claim 4, wherein the pyran photochromic group comprises a naphthopyran.

6. The display element of claim 1, wherein the dichroic compound comprises an anthraquinone dye, an azo dye, or a combination thereof.

7. The display element of claim 1, wherein the display element comprises a sheet comprising the photochromic-dichroic compound and the dichroic compound.

8. The display element of claim 1, wherein the display element comprises a first sheet comprising the photochromic-dichroic compound and a second sheet comprising the dichroic compound.

9. The display element according to claim 1, further comprising a substrate.

10. The display element of claim 9, further comprising a coating coupled to the substrate, the coating comprising the photochromic-dichroic compound and the dichroic compound.

11. The display element of claim 10, wherein the coating comprises at least one self-assembling material.

12. The display element of claim 11, wherein the self-assembling material comprises a liquid crystal material, a block copolymer, and combinations thereof.

13. The display element of claim 9, further comprising an alignment layer and a coating comprising the photochromic-dichroic compound and the dichroic compound, wherein the coating is attached to the alignment layer.

14. The display element of claim 13, wherein the alignment layer comprises a photoalignment layer.

15. The display element of claim 9, further comprising a first coating layer coupled to the substrate, the first coating layer comprising the photochromic-dichroic compound, and a second coating layer coupled to the substrate, the second coating layer comprising the dichroic compound.

16. The display element of claim 1, wherein the weight ratio of the dichroic compound to the photochromic-dichroic compound is from 0.005:1 to 0.150: 1.

17. The display element of claim 1, further comprising a birefringent layer.

18. The display element of claim 17, wherein the birefringent layer comprises quarter-glass.

19. A display device comprising the display element according to claim 1.

20. The display device of claim 19, wherein the display device further comprises an organic light emitting diode, a liquid crystal display, a plasma display panel, an electroluminescent display, or a cathode ray tube.

21. The display device of claim 19, further comprising:

a light emitting layer;

a reflective backing layer;

a quarter-wave retarder; and

at least one layer comprising the photochromic-dichroic compound, the dichroic compound, or a combination thereof.

22. The display device according to claim 21, wherein the light-emitting layer comprises a light-emitting diode or an organic light-emitting diode.

23. The display device of claim 22, wherein the display device comprises a first layer and a second layer, wherein the first layer comprises the photochromic-dichroic compound and the second layer comprises the dichroic compound.

24. The display device of claim 23, wherein the display device further comprises a quarter-wave plate coupled to the first layer, and the first layer is coupled to the second layer.