Patent Application
20160272889
The present invention relates to liquid crystal display devices.
Liquid crystal display devices are used in various products, including clocks, calculators, household electrical appliances, measuring instruments, automotive instrument panels, word processors, electronic organizers, printers, computers, and televisions. Typical types of liquid crystal display devices include twisted nematic (TN), super-twisted nematic (STN), dynamic scattering (DS), guest-host (GH), in-plane switching (IPS), fringe-field switching (FFS), optically compensated birefringence (OCB), electrically controlled birefringence (ECB), vertically aligned (VA), color super-homeotropic (CSH), and ferroelectric liquid crystal (FLC) display devices. Although conventional liquid crystal display devices are statically driven, multiplexed liquid crystal display devices have been commonly used. Among the mainstream schemes are passive-matrix driving and, more recently, active-matrix (AM) driving with elements such as thin-film transistors (TFTs) and thin-film diodes (TFDs).
Silicon-based semiconductors are known for use in thin-film transistors for active-matrix driving. Recently, thin-film transistors fabricated from oxide semiconductors, such as zinc oxide and In—Ga—Zn—O, have also attracted attention for use in liquid crystal display devices (see PTL 1). Oxide semiconductor thin-film transistors have higher field-effect mobilities than silicon-based thin-film transistors and thus allow for improved display device performance and reduced power consumption. Accordingly, liquid crystal device manufacturers are focusing their efforts on the development of oxide semiconductor thin-film transistors, including the use of arrays thereof.
Unfortunately, oxide semiconductor thin-film transistors have low reliability due to variations in electrical characteristics. The variations in electrical characteristics are attributable to lattice defects, such as oxygen defects, which occur when oxygen desorbs from an oxide semiconductor layer. As a solution to this problem, a method has been researched that involves controlling the oxygen atmosphere conditions during the deposition of an oxide semiconductor to reduce the electron carrier concentration so that fewer oxygen defects occur (see PTL 2).
A liquid crystal composition used for a liquid crystal layer of a liquid crystal display device is subjected to strict impurity control since impurities present in the composition greatly affect the electrical characteristics of the display device. It is also known that impurities remaining in the material used for alignment layers, which directly contact the liquid crystal layer, migrate into the liquid crystal layer and affect the electrical characteristics thereof. Accordingly, research has been conducted on the influence of impurities in alignment layer materials on the characteristics of liquid crystal display devices.
Although research has been conducted on various solutions to the problem of lattice defects such as oxygen defects, as discussed in PTL 2, they have been unsuccessful in sufficiently reducing the desorption of oxygen from an oxide semiconductor layer. As oxygen desorbs from an oxide semiconductor layer, it diffuses into and alters an insulating layer covering the oxide semiconductor layer. A typical liquid crystal display device includes only a thin insulating layer, or a thin insulating layer and a thin alignment layer, between oxide semiconductor layers of thin-film transistors and a liquid crystal layer to separate the liquid crystal composition from the oxide semiconductor layer; therefore, the diffusion of oxygen desorbed from the oxide semiconductor layer and the resulting alteration of the insulating layer result in insufficient separation of the liquid crystal layer from the oxide semiconductor layer. As a result, the oxygen desorbed from the oxide semiconductor layer will affect the liquid crystal layer.
The diffusion of impurities such as oxygen desorbed from the oxide semiconductor layer into the liquid crystal layer may decrease the voltage holding ratio (VHR) and increase the ion density (ID) of the liquid crystal layer and may thus cause display defects such as white spots, uneven alignment, and image-sticking.
However, as disclosed in PTL 2, the previous inventions are intended to reduce the desorption of oxygen from oxide semiconductors; no research has been conducted on the direct relationship between oxide semiconductor thin-film transistors and liquid crystal compositions.
PTL 1: Japanese Unexamined Patent Application Publication No. 2007-96055
PTL 2: Japanese Unexamined Patent Application Publication No. 2006-165528
Accordingly, an object of the present invention is to provide a liquid crystal display device, including an oxide semiconductor, that does not exhibit a significant decrease in voltage holding ratio (VHR) or increase in ion density (ID) of the liquid crystal layer and thus does not suffer from the problem of display defects such as white spots, uneven alignment, and image-sticking.
To achieve the foregoing object, the inventors have conducted extensive research on various liquid crystal compositions suitable for liquid crystal display devices including oxide semiconductor thin-film transistors. As a result, the inventors have discovered that a liquid crystal display device including a liquid crystal layer containing a particular liquid crystal composition does not exhibit a significant decrease in voltage holding ratio (VHR) or increase in ion density (ID) of the liquid crystal layer and thus does not suffer from the problem of display defects such as white spots, uneven alignment, and image-sticking and also consumes less power. This discovery has led to the present invention.
Specifically, the present invention provides a liquid crystal display device including first and second opposing substrates, a liquid crystal layer containing a liquid crystal composition between the first and second substrates, a plurality of gate lines and data lines arranged in a matrix on the first substrate, thin-film transistors disposed at intersections of the gate lines and the data lines, and pixel electrodes that are driven by the transistors and that are made of a transparent conductive material. Each thin-film transistor includes a gate electrode, an oxide semiconductor layer disposed over the gate electrode with an insulating layer therebetween, and source and drain electrodes electrically connected to the oxide semiconductor layer. The liquid crystal composition contains at least one compound selected from the group consisting of compounds represented by general formulas (LC3) to (LC5).
In the formulas, RLC31, RLC32, RLC41, RLC42, RLC51, and RLC52 are each independently an alkyl group of 1 to 15 carbon atoms, where one or more —CH2— groups in the alkyl group are optionally replaced with —O—, —CH═CH—, —CO—, —OCO—, —COO—, or —C≡C— such that no oxygen atoms are directly adjacent to each other, and one or more hydrogen atoms in the alkyl group are optionally replaced with halogen. ALC31, ALC32, ALC41, ALC42, ALC51, and ALC52 are each independently any of the following structures.
In the structures, one or more —CH2— groups in the cyclohexylene group are optionally replaced with oxygen; one or more —CH═ groups in the 1,4-phenylene group are optionally replaced with nitrogen; and one or more hydrogen atoms in the structures are optionally replaced with fluorine, chlorine, —CF3, or —OCF3. ZLC31, ZLC32, ZLC41, ZLC42, ZLC51, and ZLC51 are each independently a single bond, —CH═CH—, —C≡C—, —CH2CH2—, —(CH2)4—, —COO—, —OCH2—, —CH2O—, —OCF2—, or —CF2O—. Z5 is —CH2— or oxygen. XLC41 is hydrogen or fluorine. mLC31, mLC32, mLC41, mLC42, mLC51, and mLC52 are each independently 0 to 3. mLC31+mLC32, mLC41+mLC42, and mLC51+mLC52 are each 1, 2, or 3. Each occurrence of ALC31 to ALC52 and ZLC31 to ZLC52, if present, may be the same or different. The liquid crystal composition further contains at least one compound selected from the group consisting of compounds represented by general formulas (II-a) to (II-f).
In the formulas, R19 to R30 are each independently an alkyl group of 1 to 10 carbon atoms, an alkoxy group of 1 to 10 carbon atoms, or an alkenyl group of 2 to 10 carbon atoms; and X21 is hydrogen or fluorine.
The liquid crystal display device according to the present invention, which includes oxide semiconductor TFTs and a particular liquid crystal composition, does not exhibit a significant decrease in voltage holding ratio (VHR) or increase in ion density (ID) of the liquid crystal layer and thus does not suffer from display defects such as white spots, uneven alignment, and image-sticking and also consumes less power.
A liquid crystal display device according to a first preferred embodiment of the present invention includes oxide semiconductor thin-film transistors and a particular liquid crystal composition and generates a substantially perpendicular electric field between first and second substrates. The liquid crystal display device according to the first preferred embodiment is a liquid crystal display device having electrodes on both first and second substrates, for example, a vertically aligned (VA) transmissive liquid crystal display device.
The liquid crystal display device according to the first preferred embodiment of the present invention preferably includes first and second opposing substrates, a liquid crystal layer containing a liquid crystal composition between the first and second substrates, a plurality of gate bus lines and data bus lines arranged in a matrix on the first substrate, thin-film transistors disposed at intersections of the gate bus lines and the data bus lines, and pixel electrodes that are driven by the transistors and that are made of a transparent conductive material. Each thin-film transistor preferably includes a gate electrode, an oxide semiconductor layer disposed over the gate electrode with an insulating layer therebetween, and source and drain electrodes electrically connected to the oxide semiconductor layer. The liquid crystal display device preferably further includes a common electrode made of a transparent conductive material on the second substrate. The liquid crystal layer is preferably homeotropically aligned when no voltage is applied.
An example liquid crystal display device according to the first embodiment is illustrated in
As shown in
As shown in
That is, the liquid crystal display device 100 according to the present invention includes, in sequence, the first polarizer 101, the first substrate 102, the electrode layer 103 including the thin-film transistors (also referred to as “thin-film transistor layer”), the alignment layer 104, the layer 105 containing the liquid crystal composition, the alignment layer 104, the common electrode 106, the color filter 107, the second substrate 108, and the first polarizer 109.
As shown in
The first substrate 102 and the second substrate 108 may be made of a glass or a flexible transparent material such as a plastic, and one of them may be made of a nontransparent material such as silicon. The two substrates 1102 and 108 are bonded together with a sealant, such as a thermosetting epoxy composition, applied to the periphery thereof. The distance between the two substrates 102 and 108 may be maintained, for example, using spacer particles such as glass, plastic, or alumina particles or resin spacer pillars formed by photolithography.
The liquid crystal display device according to the present invention preferably includes inverted-staggered thin-film transistors. As shown in
As used herein, the phrase “on a substrate” refers to both direct and indirect contact with the substrate and encompasses the situation where an element is supported by the substrate.
The semiconductor layer 113 according to the present invention is made of an oxide semiconductor. The oxide semiconductor preferably contains at least one element selected from In, Ga, Zn, and Sn. To reduce variations in the electrical characteristics of the oxide transistors, the oxide semiconductor may further contain one or more of hafnium (Hf), zirconium (Zr), aluminum (Al), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu).
Examples of oxide semiconductors include indium oxide, tin oxide, zinc oxide, and gallium oxide. Oxides containing a plurality of metal elements can also be used, including In—Zn-based, Sn—Zn-based, Al—Zn-based, Zn—Mg-based, Sn—Mg-based, In—Mg-based, In—Ga-based, In—Ga—Zn-based, In—Al—Zn-based, In—Sn—Zn-based, Sn—Ga—Zn-based, Al—Ga—Zn-based, Sn—Al—Zn-based, In—Hf—Zn-based, In—Zr—Zn-based, In—La—Zn-based, In—Ce—Zn-based, In—Pr—Zn-based, In—Nd—Zn-based, In—Sm—Zn-based, In—Eu—Zn-based, In—Gd—Zn-based, In—Tb—Zn-based, In—Dy—Zn-based, In—Ho—Zn-based, In—Er—Zn-based, In—Tm—Zn-based, In—Yb—Zn-based, In—Lu—Zn-based, In—Sn—Ga—Zn-based, In—Hf—Ga—Zn-based, In—Al—Ga—Zn-based, In—Sn—Al—Zn-based, In—Sn—Hf—Zn-based, and In—Hf—Al—Zn-based oxides. In—Ga—Zn-based oxides (IGZO), which are oxides containing In, Ga, and Zn, are preferred to reduce the power consumption of the liquid crystal display device and to improve the characteristics such as transmittance of the liquid crystal display device.
For example, the term “In—Ga—Zn-based oxide” refers to an oxide containing In, Ga, and Zn, which may be present in any ratio. Metal elements other than In, Ga, and Zn may also be present.
These are non-limiting examples, and any oxide semiconductor of suitable composition may be used depending on the required semiconductor characteristics (e.g., mobility, threshold, and variations). To achieve the required semiconductor characteristics, it is also preferred to optimize other properties such as carrier density, impurity concentration, defect density, the atomic ratios of metal elements to oxygen, interatomic distance, and density.
The oxide semiconductor layer 113 takes the form of, for example, a monocrystalline, polycrystalline, C-axis aligned crystalline (CAAC), or amorphous film. Preferably, the oxide semiconductor layer 113 is a C-axis aligned crystalline oxide semiconductor (CAAC-OS) film. Some of the oxygen atoms forming the oxide semiconductor film may be replaced with nitrogen.
Oxide semiconductor thin-film transistors allow only a small current to flow in an off state (off current), retain electrical signals such as image signals for a long period of time, and allow a long write cycle to be set in an on state. This provides the advantage of reducing the refresh rate and thus reducing the power consumption. Oxide semiconductor thin-film transistors also have high field-effect mobility, which allows them to operate at high speed. Oxide semiconductor thin-film transistors also have a smaller size than conventional thin-film transistors, which allows more light to pass through each pixel. Thus, the use of oxide semiconductor thin-film transistors in the pixels of the liquid crystal display device provides a high-quality image. It is also preferred to use a transparent oxide semiconductor film, which reduces the influence of photocarriers due to light absorption and thus increases the aperture ratio of the device.
An ohmic contact layer may be disposed between the semiconductor layer 113 and the drain electrode 116 or the source electrode 117 to reduce the width and height of the Schottky barrier. The ohmic contact layer may be made of a material heavily doped with an impurity such as phosphorus, for example, n-type amorphous silicon or n-type polycrystalline silicon.
The gate bus lines 126 and the data bus lines 125 are preferably made of a metal film, more preferably Al, Cu, Au, Ag, Cr, Ta, Ti, Mo, W, Ni, or an alloy thereof, even more preferably Al or an alloy thereof. The gate bus lines 126 and the data bus lines 125 overlap each other with the gate insulating layer therebetween. The insulating protective layer 118, which functions as an insulator, is made of, for example, a silicon nitride, silicon dioxide, or silicon oxynitride film.
A conductive metal oxide may be used as a transparent electrode material for the pixel electrodes 121 and the transparent electrode (layer) 106 (also referred to as “common electrode 106”) of the liquid crystal display device according to the present invention. Examples of metal oxides that can be used include indium oxide (In2O3), tin oxide (SnO2), zinc oxide (ZnO), indium tin oxide (InzO3—SnO2), indium zinc oxide (In2O3—ZnO), niobium-doped titanium dioxide (Ti1-xNbxO2), fluorine-doped tin oxide, graphene nanoribbons, and metal nanowires, preferably zinc oxide (ZnO), indium tin oxide (In2O3—SnO2), and indium zinc oxide (In2O3—ZnO). These transparent conductive films may be patterned by techniques such as photoetching and mask patterning.
The color filter 107 includes a black matrix and pixel regions of at least three colors including RGB. To reduce the leakage of light, the black matrix (not shown) is preferably formed in the area of the color filter 107 corresponding to the thin-film transistors and the storage capacitors 123.
The liquid crystal display device according to the present invention may include alignment layers disposed on the surfaces of the first and second substrates adjacent to the liquid crystal composition to align the liquid crystal composition. If the liquid crystal display device requires an alignment layer, it may be disposed between the color filter and the liquid crystal layer. Even a thick alignment layer has a thickness of only 100 nm or less, which is insufficient to completely reduce the diffusion of oxygen desorbed from the oxide semiconductor layer 113 into the liquid crystal layer 5.
If the liquid crystal display device includes no alignment layer, a larger interaction occurs between the oxide semiconductor layer and the liquid crystal compounds forming the liquid crystal layer.
Examples of alignment layer materials that can be used include transparent organic materials such as polyimides, polyamides, benzocyclobutene (BCB) polymers, and polyvinyl alcohol. Particularly preferred are polyimide alignment layers, which are formed by the imidation of polyamic acids synthesized from diamines such as aliphatic and alicyclic diamines, including p-phenylenediamine and 4,4′-diaminodiphenylmethane, and aliphatic and alicyclic tetracarboxylic anhydrides such as butanetetracarboxylic anhydride and 2,3,5-tricarboxycyclopentylacetic anhydride or aromatic tetracarboxylic anhydrides such as pyromellitic dianhydride. Although a typical alignment process for polyimide alignment layers is rubbing, they may be used without an alignment process, for example, if they are used as vertical alignment layers.
Other alignment layer materials include those containing a chalcone, cinnamate, cinnamoyl, or azo group in the compound. These alignment layer materials may be used in combination with other materials such as polyimides and polyamides. These alignment layers may be subjected to either rubbing or photoalignment.
Although a typical alignment layer is a resin layer formed by applying an alignment layer material to a substrate using a process such as spin coating, other techniques such as uniaxial drawing and the Langmuir-Blodgett technique may also be used.
The liquid crystal layer of the liquid crystal display device according to the present invention contains at least one compound selected from the group consisting of compounds represented by general formulas (LC3) to (LC5).
In the formulas, RLC31, RLC32, RLC41, RLC42, RLC51, and RLC52 are each independently an alkyl group of 1 to 15 carbon atoms, where one or more —CH2— groups in the alkyl group are optionally replaced with —O—, —CH═CH—, —CO—, —OCO—, —COO—, or —C≡C— such that no oxygen atoms are directly adjacent to each other, and one or more hydrogen atoms in the alkyl group are optionally replaced with halogen. ALC31, ALC32, ALC41, ALC42, ALC51, and ALC52 are each independently any of the following structures.
In the structures, one or more —CH2— groups in the cyclohexylene group are optionally replaced with oxygen; one or more —CH═ groups in the 1,4-phenylene group are optionally replaced with nitrogen; and one or more hydrogen atoms in the structures are optionally replaced with fluorine, chlorine, —CF3, or —OCF3. ZLC31, ZLC32, ZLC41, ZLC42, ZLC51, and ZLC51 are each independently a single bond, —CH═CH—, —C≡C—, —CH2CH2—, —(CH2)4—, —COO—, —OCH2—, —CH2O—, —OCF2—, or —CF2O—. Z5 is —CH2— or oxygen. XLC41 is hydrogen or fluorine. mLC31, mLC32, mLC41, mLC42, mLC51, and mLC52 are each independently 0 to 3. mLC31+mLC32, mLC41+mLC42, and mLC51+mLC52 are each 1, 2, or 3. Each occurrence of ALC31 to ALC52 and ZLC31 to ZLC52, if present, may be the same or different.
RLC31 to RLC52 are preferably each independently an alkyl group of 1 to 7 carbon atoms, an alkoxy group of 1 to 7 carbon atoms, or an alkenyl group of 2 to 7 carbon atoms. Most preferred are alkenyl groups having the following structures.
In the formulas, the right end is linked to the cyclic structure.
ALC31 to ALC52 are preferably each independently any of the following structures.
ZLC31 to ZLC51 are preferably each independently a single bond, —CH2O—, —COO—, —OCO—, —CH2CH2—, —CF2O—, —OCF2—, or —OCH2—.
The liquid crystal layer preferably contains, as the compounds represented by general formulas (LC3), (LC4), and (LC5), at least one compound selected from the group consisting of compounds represented by general formulas (LC3-1), (LC4-1), and (LC5-1).
In the formulas, R31 to R33 are each an alkyl group of 1 to 8 carbon atoms, an alkenyl group of 2 to 8 carbon atoms, an alkoxy group of 1 to 8 carbon atoms, or an alkenyloxy group of 2 to 8 carbon atoms; R41 to R43 are each an alkyl group of 1 to 8 carbon atoms, an alkenyl group of 2 to 8 carbon atoms, an alkoxy group of 1 to 8 carbon atoms, or an alkenyloxy group of 2 to 8 carbon atoms; Z3′ to Z33 are each a single bond, —CH═CH—, —C≡C—, —CH2CH2—, —(CH2)4—, —COO—, —OCO—, —OCH2—, —CH2O—, —OCF2—, or —CF2O—; X41 is hydrogen or fluorine; and Z34 is —CH2— or oxygen.
Although R31 to R33 in general formulas (LC3-1) to (LC5-1) are each an alkyl group of 1 to 8 carbon atoms, an alkenyl group of 2 to 8 carbon atoms, an alkoxy group of 1 to 8 carbon atoms, or an alkenyloxy group of 2 to 8 carbon atoms, R31 to R33 are each preferably an alkyl group of 1 to 5 carbon atoms or an alkenyl group of 2 to 5 carbon atoms, more preferably an alkyl group of 2 to 5 carbon atoms or an alkenyl group of 2 to 4 carbon atoms, even more preferably an alkyl group of 3 to 5 carbon atoms or an alkenyl group of 2 carbon atoms, still even more preferably an alkyl group of 3 carbon atoms.
Although R41 to R43 are each an alkyl group of 1 to 8 carbon atoms, an alkenyl group of 2 to 8 carbon atoms, an alkoxy group of 1 to 8 carbon atoms, or an alkenyloxy group of 2 to 8 carbon atoms, R41 to R43 are each preferably an alkyl group of 1 to 5 carbon atoms, an alkoxy group of 1 to 5 carbon atoms, an alkenyl group of 4 to 8 carbon atoms, or an alkenyloxy group of 3 to 8 carbon atoms, more preferably an alkyl group of 1 to 3 carbon atoms or an alkoxy group of 1 to 3 carbon atoms, even more preferably an alkyl group of 3 carbon atoms or an alkoxy group of 2 carbon atoms, still even more preferably an alkoxy group of 2 carbon atoms.
Although Z31 to Z33 are each a single bond, —CH═CH—, —C≡C—, —CH2CH2—, —(CH2)4—, —COO—, —OCO—, —OCH2—, —CH2O—, —OCF2—, or —CF2O—, Z31 to Z33 are each preferably a single bond, —CH2CH2—, —COO—, —OCH2—, —CH2O—, —OCF2—, or —CF2O—, more preferably a single bond or —CH2O—.
The compound selected from the group consisting of compounds represented by general formulas (LC3-1), (LC4-1), and (LC5-1) is preferably present in the liquid crystal composition in an amount of 5% to 50% by mass, more preferably 5% to 40% by mass, even more preferably 5% to 30% by mass, still even more preferably 8% to 27% by mass, further preferably 10% to 25% by mass.
Specific preferred compounds represented by general formula (LC3-1) include those represented by general formulas (LC3-11) to (LC3-14) shown below.
In the formulas, R31 is an alkyl group of 1 to 5 carbon atoms or an alkenyl group of 2 to 5 carbon atoms; and R41a is an alkyl group of 1 to 5 carbon atoms.
Specific preferred compounds represented by general formula (LC4-1) include those represented by general formulas (LC4-11) to (LC4-14) shown below.
In the formulas, R32 is an alkyl group of 1 to 5 carbon atoms or an alkenyl group of 2 to 5 carbon atoms; R42a is an alkyl group of 1 to 5 carbon atoms; and X41 is hydrogen or fluorine.
Specific preferred compounds represented by general formula (LC5-1) include those represented by general formulas (LC5-11) to (LC5-14) shown below.
In the formulas, R33 is an alkyl group of 1 to 5 carbon atoms or an alkenyl group of 2 to 5 carbon atoms; R43a is an alkyl group of 1 to 5 carbon atoms; and Z34 is —CH2— or oxygen.
In general formulas (LC3-11), (LC3-13), (LC4-11), (LC4-13), (LC5-11), and (LC5-13), R31 to R33 are each preferably as defined in general formulas (LC3-1) to (LC5-1). R41a to R41c are each preferably an alkyl group of 1 to 3 carbon atoms, more preferably an alkyl group of 1 or 2 carbon atoms, even more preferably an alkyl group of 2 carbon atoms.
In general formulas (LC3-12), (LC3-14), (LC4-12), (LC4-14), (LC5-12), and (LC5-14), R31 to R33 are each preferably as defined in general formula (II-1). R41a to R41c are each preferably an alkyl group of 1 to 3 carbon atoms, more preferably an alkyl group of 1 or 3 carbon atoms, even more preferably an alkyl group of 3 carbon atoms.
Among general formulas (LC3-11) to (LC5-14), general formulas (LC3-11), (LC4-11), (LC5-11), (LC3-13), (LC4-13) and (LC5-13) are preferred to achieve a larger absolute value of dielectric anisotropy. General formulas (LC3-11), (LC4-11), and (LC5-11) are more preferred.
The liquid crystal layer of the liquid crystal display device according to the present invention preferably contains one or more compounds, more preferably one or two compounds, selected from compounds represented by general formulas (LC3-11) to (LC5-14), and preferably contains one or two compounds represented by general formula (LC3-1).
Also preferably, the liquid crystal layer contains, as the compounds represented by general formulas (LC3), (LC4), and (LC5), at least one compound selected from the group consisting of compounds represented by general formulas (LC3-2), (LC4-2), and (LC5-2).
In the formulas, R51 to R53 are each an alkyl group of 1 to 8 carbon atoms, an alkenyl group of 2 to 8 carbon atoms, an alkoxy group of 1 to 8 carbon atoms, or an alkenyloxy group of 2 to 8 carbon atoms; R61 to R63 are each an alkyl group of 1 to 8 carbon atoms, an alkenyl group of 2 to 8 carbon atoms, an alkoxy group of 1 to 8 carbon atoms, or an alkenyloxy group of 2 to 8 carbon atoms; B1 to B3 are each 1,4-phenylene or trans-1,4-cyclohexylene optionally substituted with fluorine; Z41 to Z43 are each a single bond, —CH═CH—, —C≡C—, —CH2CH2—, —(CH2)4—, —COO—, —OCO—, —OCH2—, —CH2O—, —OCF2—, or —CF2O—; X42 is hydrogen or fluorine; and Z44 is —CH2— or oxygen.
Although R51 to R53 in general formulas (LC3-2), (LC4-2), and (LC5-2) are each an alkyl group of 1 to 8 carbon atoms, an alkenyl group of 2 to 8 carbon atoms, an alkoxy group of 1 to 8 carbon atoms, or an alkenyloxy group of 2 to 8 carbon atoms, R51 to R53 are each preferably an alkyl group of 1 to 5 carbon atoms or an alkenyl group of 2 to 5 carbon atoms, more preferably an alkyl group of 2 to 5 carbon atoms or an alkenyl group of 2 to 4 carbon atoms, even more preferably an alkyl group of 3 to 5 carbon atoms or an alkenyl group of 2 carbon atoms, still even more preferably an alkyl group of 3 carbon atoms.
Although R61 to R63 are each an alkyl group of 1 to 8 carbon atoms, an alkenyl group of 2 to 8 carbon atoms, an alkoxy group of 1 to 8 carbon atoms, or an alkenyloxy group of 2 to 8 carbon atoms, R61 to R63 are each preferably an alkyl group of 1 to 5 carbon atoms, an alkoxy group of 1 to 5 carbon atoms, an alkenyl group of 4 to 8 carbon atoms, or an alkenyloxy group of 3 to 8 carbon atoms, more preferably an alkyl group of 1 to 3 carbon atoms or an alkoxy group of 1 to 3 carbon atoms, even more preferably an alkyl group of 3 carbon atoms or an alkoxy group of 2 carbon atoms, still even more preferably an alkoxy group of 2 carbon atoms.
Although B31 to B33 are 1,4-phenylene or trans-1,4-cyclohexylene optionally substituted with fluorine, B31 to B33 are preferably unsubstituted 1,4-phenylene or trans-1,4-cyclohexylene, more preferably trans-1,4-cyclohexylene.
Although Z41 to Z43 are each a single bond, —CH═CH—, —C≡C—, —CH2CH2—, —(CH2)4—, —COO—, —OCO—, —OCH2—, —CH2O—, —OCF2—, or —CF2O—, Z41 to Z43 are each preferably a single bond, —CH2CH—, —COO—, —OCH2—, —CH2O—, —OCF2—, or —CF2O—, more preferably a single bond or —CH2O—.
The compounds represented by general formulas (LC3-2), (LC4-2), and (LC5-2) are preferably present in the liquid crystal composition in an amount of 10% to 60%, more preferably 20% to 50%, even more preferably 25% to 45% by mass, still even more preferably 28% to 42% by mass, further preferably 30% to 40% by mass.
Specific preferred compounds represented by general formula (LC3-2) include those represented by general formulas (LC3-21) to (LC3-26) shown below.
In the formulas, R51 is an alkyl group of 1 to 5 carbon atoms or an alkenyl group of 2 to 5 carbon atoms; and R61a is an alkyl group of 1 to 5 carbon atoms. Preferably, R51 and R61a are as defined for R51 and R61, respectively, in general formula (LC3-2).
Specific preferred compounds represented by general formula (LC4-2) include those represented by general formulas (LC4-21) to (LC4-26) shown below.
In the formulas, R52 is an alkyl group of 1 to 5 carbon atoms or an alkenyl group of 2 to 5 carbon atoms; R62a is an alkyl group of 1 to 5 carbon atoms; and X42 is hydrogen or fluorine. Preferably, R52 and R62a are as defined for R52 and R62, respectively, in general formula (LC4-2).
Specific preferred compounds represented by general formula (LC5-2) include those represented by general formulas (LC5-21) to (LC5-26) shown below.
In the formulas, R53 is an alkyl group of 1 to 5 carbon atoms or an alkenyl group of 2 to 5 carbon atoms; R63a is an alkyl group of 1 to 5 carbon atoms; and W2 is —CH2— or oxygen. Preferably, R53 and R63a are as defined for R53 and R63, respectively, in general formula (LC5-2).
In general formulas (LC3-21), (LC3-22), (LC3-25), (LC4-21), (LC4-22), (LC4-25), (LC5-21), (LC5-22), and (LC5-25), R51 to R53 are each preferably as defined in general formulas (LC3-2), (LC4-2), and (LC5-2). R61a to R63a are each preferably an alkyl group of 1 to 3 carbon atoms, more preferably an alkyl group of 1 or 2 carbon atoms, even more preferably an alkyl group of 2 carbon atoms.
In general formulas (LC3-23), (LC3-24), (LC3-26), (LC4-23), (LC4-24), (LC4-26), (LC5-23), (LC5-24), and (LC5-26), R51 to R53 are each preferably as defined in general formulas (LC3-2), (LC4-2), and (LC5-2). R61a to R63a are each preferably an alkyl group of 1 to 3 carbon atoms, more preferably an alkyl group of 1 or 3 carbon atoms, even more preferably an alkyl group of 3 carbon atoms.
Among general formulas (LC3-21) to (LC5-26), general formulas (LC3-21), (LC3-22), (LC3-25), (LC4-21), (LC4-22), (LC4-25), (LC5-21), (LC5-22), and (LC5-25) are preferred to achieve a larger absolute value of dielectric anisotropy.
The liquid crystal layer may contain at least one compound selected from compounds represented by general formulas (LC3-2), (LC4-2) and (LC5-2). Preferably, the liquid crystal layer contains at least one compound where B1 to B3 are 1,4-phenylene and at least one compound where B1 to B3 are trans-1,4-cyclohexylene.
Also preferably, the liquid crystal layer contains, as the compounds represented by general formula (LC3), at least one compound selected from the group consisting of compounds represented by general formulas (LC3-a) and (LC3-b) below.
In the formulas, RLC31, RLC32, ALC31, and ZLC31 are each independently as defined for RLC31, RLC32, ALC31, and ZLC31, respectively, in general formula (LC3); XLC3b1 to XLC3b6 are hydrogen or fluorine, with the proviso that either XLC3b1 and XLC3b2 or XLC3b3 and XLC3b4, or both, are fluorine; and mLC3a1 is 1, 2, or 3, and mLC3b1 is 0 or 1, where each occurrence of ALC31 and ZLC31, if present, may be the same or different.
RLC31 and RLC32 are preferably each independently an alkyl group of 1 to 7 carbon atoms, an alkoxy group of 1 to 7 carbon atoms, an alkenyl group of 2 to 7 carbon atoms, or an alkenyloxy group of 2 to 7 carbon atoms.
ALC31 is preferably 1,4-phenylene, trans-1,4-cyclohexylene, tetrahydropyran-2,5-diyl, or 1,3-dioxane-2,5-diyl, more preferably 1,4-phenylene or trans-1,4-cyclohexylene.
ZLC31 is preferably a single bond, —CH2O—, —COO—, —OCO—, or —CH2CH2—, more preferably a single bond.
General formula (LC3-a) is preferably general formula (LC3-a1) below.
In the formula, RLC31 and RLC32 are each independently as defined for RLC31 and RLC32, respectively, in general formula (LC3).
RLC31 and RLC32 are preferably each independently an alkyl group of 1 to 7 carbon atoms, an alkoxy group of 1 to 7 carbon atoms, or an alkenyl group of 2 to 7 carbon atoms. More preferably, RLC31 is an alkyl group of 1 to 7 carbon atoms, and RLC32 is an alkoxy group of 1 to 7 carbon atoms.
General formula (LC3-b) is preferably any of general formulas (LC3-b1) to (LC3-b12) below, more preferably general formula (LC3-b1), (LC3-b6), (LC3-b8), or (LC3-b11), even more preferably general formula (LC3-b1) or (LC3-b6), most preferably general formula (LC3-b1).
In the formulas, RLC31 and RLC32 are each independently as defined for RLC31 and RLC32, respectively, in general formula (LC3).
RLC31 and RLC32 are preferably each independently an alkyl group of 1 to 7 carbon atoms, an alkoxy group of 1 to 7 carbon atoms, or an alkenyl group of 2 to 7 carbon atoms. More preferably, RLC31 is an alkyl group of 2 or 3 carbon atoms, and RLC32 is an alkyl group of 2 carbon atoms.
Preferred compounds represented by general formula (LC4) include those represented by general formulas (LC4-a) to (LC4-c) below. Preferred compounds represented by general formula (LC5) include those represented by general formulas (LC5-a) to (LC5-c) below.
In the formulas, RLC41, RLC42, and XLC41 are each independently as defined for RLC41, RLC42, and XLC41, respectively, in general formula (LC4); RLC51 and RLC52 are each independently as defined for RL51 and RLC52, respectively, in general formula (LC5); and ZLC4a1, ZLC4b1, ZLC4c1, ZLC5a1, ZLC5b1, and ZLC5c1 are each independently a single bond, —CH═CH—, —C≡C—, —CH2CH2—, —(CH2)4—, —COO—, —OCH2—, —CH2O—, —OCF2—, or —CF2O—.
RLC41, RLC42, RLC51, and RLC52 are each independently an alkyl group of 1 to 7 carbon atoms, an alkoxy group 1 to 7 of carbon atoms, an alkenyl group of 2 to 7 carbon atoms, or an alkenyloxy group of 2 to 7 carbon atoms.
ZLC4a1 to ZLC5c1 are preferably each independently a single bond, —CH2O—, —COO—, —OCO—, or —CH2CH2—, more preferably a single bond.
The liquid crystal layer of the liquid crystal display device according to the present invention further contains at least one compound selected from the group consisting of compounds represented by general formulas (II-a) to (II-f).
In the formulas, R19 to R30 are each independently an alkyl group of 1 to 10 carbon atoms, an alkoxy group of 1 to 10 carbon atoms, or an alkenyl group of 2 to 10 carbon atoms; and X21 is hydrogen or fluorine.
If R19 to R30 in general formulas (IIa) to (IIf) are linked to phenyl (aromatic group), they are each preferably a linear alkyl group of 1 to 5 carbon atoms, a linear alkoxy group of 1 to 4 (or more) carbon atoms, or an alkenyl group of 4 or 5 carbon atoms. If R19 to R30 are linked to a saturated cyclic structure such as cyclohexane, pyran, or dioxane, they are each preferably a linear alkyl group of 1 to 5 carbon atoms, a linear alkoxy group of 1 to 4 (or more) carbon atoms, or a linear alkenyl group of 2 to 5 carbon atoms.
If it is desirable to achieve good chemical stability to heat and light, R19 to R30 are preferably alkyl. If it is desirable to produce a liquid crystal display device with low viscosity and fast response time, R19 to R30 are preferably alkenyl. If it is desirable to achieve a low viscosity, a high nematic-isotropic phase transition temperature (Tni), and a faster response time, it is preferred to use an alkenyl group having no unsaturated bond at the end thereof, more preferably an alkenyl group having methyl at the end thereof. If it is desirable to achieve good solubility at low temperature, R19 to R30 are preferably alkoxy. Alternatively, it is preferred to use a combination of compounds having different groups at R19 to R30. For example, it is preferred to use a combination of compounds having alkyl or alkenyl groups of 2, 3, and 4 carbon atoms at R19 to R30, a combination of compounds having alkyl or alkenyl groups of 3 and 5 carbon atoms at R19 to R30, or a combination of compounds having alkyl or alkenyl groups of 3, 4, and 5 carbon atoms at R19 to R30.
R19 and R20 are each preferably alkyl or alkoxy, and at least one of them is preferably alkoxy. More preferably, R19 is alkyl, and R20 is alkoxy. Even more preferably, R19 is an alkyl group of 3 to 5 carbon atoms, and R20 is an alkoxy group of 1 or 2 carbon atoms.
R21 and R22 are each preferably alkyl or alkenyl, and at least one of them is preferably alkenyl. Although compounds where both R21 and R22 are alkenyl are preferred to achieve a faster response time, they are not preferred to improve the chemical stability of the liquid crystal display device.
At least one of R23 and R24 is preferably an alkyl group of 1 to 5 carbon atoms, an alkoxy group of 1 to 5 carbon atoms, or an alkenyl group of 4 or 5 carbon atoms. If it is desirable to achieve a good balance of response time and Tni, at least one of R23 and R24 is preferably alkenyl. If it is desirable to achieve a good balance of response time and solubility at low temperature, at least one of R23 and R24 is preferably alkoxy.
At least one of R25 and R26 is preferably an alkyl group of 1 to 5 carbon atoms, an alkoxy group of 1 to 5 carbon atoms, or an alkenyl group of 2 to 5 carbon atoms. If it is desirable to achieve a good balance of response time and Tni, at least one of R25 and R26 is preferably alkenyl. If it is desirable to achieve a good balance of response time and solubility at low temperature, at least one of R25 and R26 is preferably alkoxy. More preferably, R25 is alkenyl, and R26 is alkyl. Also preferably, R25 is alkyl, and R26 is alkoxy.
At least one of R27 and R28 is preferably an alkyl group of 1 to 5 carbon atoms, an alkoxy group of 1 to 5 carbon atoms, or an alkenyl group of 2 to 5 carbon atoms. If it is desirable to achieve a good balance of response time and Tni, at least one of R27 and R28 is preferably alkenyl. If it is desirable to achieve a good balance of response time and solubility at low temperature, at least one of R27 and R28 is preferably alkoxy. More preferably, R27 is alkyl or alkenyl, and R28 is alkyl. Also preferably, R27 is alkyl, and R28 is alkoxy. Even more preferably, R27 is alkyl, and R28 is alkyl.
X21 is preferably fluorine.
At least one of R29 and R30 is preferably an alkyl group of 1 to 5 carbon atoms or an alkenyl group of 4 or 5 carbon atoms. If it is desirable to achieve a good balance of response time and Tni, at least one of R29 and R30 is preferably alkenyl. If it is desirable to achieve good reliability, at least one of R29 and R30 is preferably alkyl. More preferably, R29 is alkyl or alkenyl, and R30 is alkyl or alkenyl. Also preferably, R29 is alkyl, and R30 is alkenyl. Also preferably, R29 is alkyl, and R30 is alkyl.
The liquid crystal layer preferably contains one to ten, more preferably one to eight, compounds selected from the group consisting of compounds represented by general formulas (II-a) to (II-f). These compounds are preferably present in an amount of 5% to 80% by mass, more preferably 10% to 70% by mass, even more preferably 20% to 60% by mass, still even more preferably 30% to 50% by mass, further preferably 32% to 48% by mass, even further preferably 34% to 46% by mass.
The liquid crystal layer of the liquid crystal display device according to the present invention preferably further contains a compound represented by general formula (LC).
In general formula (LC),
RLC is an alkyl group of 1 to 15 carbon atoms, where one or more —CH2— groups in the alkyl group are optionally replaced with —O—, —CH═CH—, —CO—, —OCO—, —COO—, or —C≡C— such that no oxygen atoms are directly adjacent to each other, and one or more hydrogen atoms in the alkyl group are optionally replaced with halogen;
ALC1 and ALC2 are each independently a group selected from the group consisting of
(a) trans-1,4-cyclohexylene (where one or more non-adjacent —CH2— groups present in the group are optionally replaced with oxygen or sulfur),
(b) 1,4-phenylene (where one or more non-adjacent —CH═ groups present in the group are optionally replaced with nitrogen), and
(c) 1,4-bicyclo(2.2.2)octylene, naphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, and chromane-2,6-diyl, where one or more hydrogen atoms present in groups (a), (b), and (c) are each optionally replaced with fluorine, chlorine, —CF3, or —OCF3;
ZLC is a single bond, —CH═CH—, —CF═CF—, —C≡C—, —CH2CH2—, —(CH2)4—, —OCH2—, —CH2O—, —OCF2—, —CF2O—, —COO—, or —OCO—;
YLC is hydrogen, fluorine, chlorine, cyano, or an alkyl group of 1 to 15 carbon atoms, where one or more —CH2— groups in the alkyl group are optionally replaced with —O—, —CH═CH—, —CO—, —OCO—, —COO—, —C≡C—, —CF2O—, or —OCF2— such that no oxygen atoms are directly adjacent to each other, and one or more hydrogen atoms in the alkyl group are optionally replaced with halogen; and
a is an integer of 1 to 4, where if a is 2, 3, or 4, each occurrence of ALC1 may be the same or different, and each occurrence of ZLC may be the same or different,
with the proviso that compounds represented by general formulas (LC3), (LC4), (LC5), and (II-a) to (II-f) are excluded.
The liquid crystal layer preferably contains one to ten, more preferably one to eight, compounds selected from the group consisting of compounds represented by general formula (LC). These compounds are preferably present in an amount of 5% to 50% by mass, more preferably 10% to 40% by mass.
To achieve a faster response time, the liquid crystal composition preferably contains, as the compound represented by general formula (LC), at least one compound represented by general formula (LC6) below.
In the formula, RLC61 and RLC62 are each independently an alkyl group of 1 to 15 carbon atoms, where one or more —CH2— groups in the alkyl group are optionally replaced with —O—, —CH═CH—, —CO—, —OCO—, —COO—, or —C≡C— such that no oxygen atoms are directly adjacent to each other, and one or more hydrogen atoms in the alkyl group are optionally replaced with halogen. ALC61 to ALC63 are each independently any of the following structures.
In the structures, one or more —CH2— groups in the cyclohexylene group are optionally replaced with —CH═CH—, —CF2O—, or —OCF2—, and one or more CH groups in the 1,4-phenylene group are optionally replaced with nitrogen. ZLC61 and ZLC62 are each independently a single bond, —CH═CH—, —C≡C—, —CH2CH2—, —(CH2)4—, —COO—, —OCH2—, —CH2O—, —OCF2—, or —CF2O—. miii1 is 0 to 3. Compounds represented by general formula (I) are excluded.
RLC61 and RLC62 are preferably each independently an alkyl group of 1 to 7 carbon atoms, an alkoxy group of 1 to 7 carbon atoms, or an alkenyl group of 2 to 7 carbon atoms. Most preferred are alkenyl groups having the following structures.
In the formulas, the right end is linked to the cyclic structure.
ALC61 to ALC63 are preferably each independently any of the following structures.
ZLC61 and ZLC62 are preferably each independently a single bond, —CH2CH2—, —COO—, —OCH2—, —CH2O—, —OCF2—, or —CF2O—.
More preferably, the liquid crystal layer contains, as the compound represented by general formula (LC6), at least one compound selected from the group consisting of compounds represented by general formulas (LC6-a) to (LC6-g).
In the formulas, RLC61 and RLC62 are each independently an alkyl group of 1 to 7 carbon atoms, an alkoxy group of 1 to 7 carbon atoms, an alkenyl group of 2 to 7 carbon atoms, or an alkenyloxy group of 2 to 7 carbon atoms.
The compounds represented by general formulas (LC3) to (LC5), which have relatively large absolute values of negative dielectric anisotropy, are preferably present in a total amount of 30% to 65%, more preferably 40% to 55%, even more preferably 43% to 50%.
The compounds represented by general formula (LC) include both those with positive dielectric anisotropy and those with negative dielectric anisotropy. If compounds with absolute values of negative dielectric anisotropy of 0.3 or more are used, the compounds represented by general formulas (LC3) to (LC5) and (LC) are preferably present in a total amount of 35% to 70%, more preferably 45% to 65%, even more preferably 50% to 60%.
Preferably, the compounds represented by general formulas (II-a) to (II-f) are present in an amount of 30% to 50%, and the compounds represented by general formulas (LC3) to (LC5) and (LC) are present in an amount of 35% to 70%. More preferably, the compounds represented by general formulas (II-a) to (II-f) are present in an amount of 35% to 45%, and the compounds represented by general formulas (LC3) to (LC5) and (LC) are present in an amount of 45% to 65%. Even more preferably, the compounds represented by general formulas (II-a) to (II-f) are present in an amount of 38% to 42%, and the compounds represented by general formulas (LC3) to (LC5) and (LC) are present in an amount of 50% to 60%.
The compounds represented by general formulas (LC3) to (LC5), (II-a) to (II-f), and (LC) are preferably present in a total amount of 80% to 100%, more preferably 90% to 100%, even more preferably 95% to 100%, of the total composition.
Although the liquid crystal layer of the liquid crystal display device according to the present invention can have a wide range of nematic phase-isotropic liquid phase transition temperature (Tni), the nematic phase-isotropic liquid phase transition temperature (Tni) is preferably 60° C. to 120° C., more preferably 70° C. to 100° C., even more preferably 70° C. to 85° C.
The dielectric anisotropy at 25° C. is preferably −2.0 to −6.0, more preferably −2.5 to −5.0, even more preferably −2.5 to −4.0.
The refractive index anisotropy at 25° C. is preferably 0.08 to 0.13, more preferably 0.09 to 0.12. Specifically, the refractive index anisotropy at 25° C. is preferably 0.10 to 0.12 for small cell gaps and is preferably 0.08 to 0.10 for large cell gaps.
The rotational viscosity (γ1) is preferably 150 or less, more preferably 130 or less, even more preferably 120 or less.
The liquid crystal layer of the liquid crystal display device according to the present invention preferably has a particular value of Z, which is a function of rotational viscosity and refractive index anisotropy.
Z=γ1/Δn2 [Math. 11]
In the formula, γ1 is the rotational viscosity, and Δn is the refractive index anisotropy.
Z is preferably 13,000 or less, more preferably 12,000 or less, even more preferably 11,000 or less.
The liquid crystal layer of the liquid crystal display device according to the present invention, when used in an active-matrix display device, preferably has a resistivity of 1012 Ω·m or more, more preferably 1013 Ω·m, even more preferably 1014 Ω·m or more.
In addition to the compounds discussed above, the liquid crystal layer of the liquid crystal display device according to the present invention may contain other ingredients depending on the application, including common nematic, smectic, and cholesteric liquid crystals, antioxidants, ultraviolet absorbers, and polymerizable monomers.
The liquid crystal layer may contain, as a polymerizable monomer, a polymerizable compound containing one reactive group, i.e., a monofunctional polymerizable compound, or a polymerizable compound containing two or more reactive groups, i.e., a polyfunctional polymerizable compound, such as a di- or trifunctional polymerizable compound. The reactive-group-containing polymerizable compounds may or may not contain a mesogenic moiety.
The reactive-group-containing polymerizable compounds preferably contain a photopolymerizable substituent, particularly if vertical alignment layers are formed by thermal polymerization. This reduces the reaction of the reactive-group-containing polymerizable compounds during the thermal polymerization of the vertical alignment layer material.
Among reactive-group-containing polymerizable compounds, specific preferred monofunctional reactive-group-containing polymerizable compounds include polymerizable compounds represented by general formula (VI) below.
In the formula, X3 is hydrogen or methyl; Sp3 is a single bond, an alkylene group of 1 to 8 carbon atoms, or —O—(CH2)t— (where t is an integer of 2 to 7, and the oxygen atom is linked to the aromatic ring); V is a linear or branched polyvalent alkylene group of 2 to 20 carbon atoms or a polyvalent cyclic substituent of 5 to 30 carbon atoms, where the alkylene group in the polyvalent alkylene group is optionally substituted with oxygen such that no oxygen atoms are adjacent to each other and is optionally substituted with an alkyl group of 5 to 20 carbon atoms (where the alkylene group in the group is optionally substituted with oxygen such that no oxygen atoms are adjacent to each other) or a cyclic substituent; and W is hydrogen, halogen, or an alkylene group of 1 to 8 carbon atoms.
Although X3 in general formula (VI) above is hydrogen or methyl, X3 is preferably hydrogen if it is desirable to achieve a higher reaction rate and is preferably methyl if it is desirable to achieve a lower residual monomer content.
Although Sp3 in general formula (VI) above is a single bond, an alkylene group of 1 to 8 carbon atoms, or —O—(CH2)t— (where t is an integer of 2 to 7, and the oxygen atom is linked to the aromatic ring), shorter carbon chains are preferred. Specifically, Sp3 is preferably a single bond or an alkylene group of 1 to 5 carbon atoms, more preferably a single bond or an alkylene group of 1 to 3 carbon atoms. If Sp3 is —O—(CH2)t—, t is preferably 1 to 5, more preferably 1 to 3.
Although V in general formula (VI) above is a linear or branched polyvalent alkylene group of 2 to 20 carbon atoms or a polyvalent cyclic substituent of 5 to 30 carbon atoms, the alkylene group in the polyvalent alkylene group may optionally be substituted with oxygen such that no oxygen atoms are adjacent to each other and may optionally be substituted with an alkyl group of 5 to 20 carbon atoms (where the alkylene group in the group is optionally substituted with oxygen such that no oxygen atoms are adjacent to each other) or a cyclic substituent, preferably with two or more cyclic substituents.
Specific polymerizable compounds represented by general formula (VI) include compounds represented by general formula (X1a).
In the formula,
A1 is hydrogen or methyl;
A2 is a single bond or an alkylene group of 1 to 8 carbon atoms (where one or more methylene groups in the alkylene group are each independently optionally replaced with oxygen, —CO—, —COO—, or —OCO— such that no oxygen atoms are directly linked to each other, and one or more hydrogen atoms in the alkylene group are each independently optionally replaced with fluorine, methyl, or ethyl);
A3 and A6 are each independently hydrogen, halogen, or an alkyl group of 1 to 10 carbon atoms (where one or more methylene groups in the alkyl group are each independently optionally replaced with oxygen, —CO—, —COO—, or —OCO— such that no oxygen atoms are directly linked to each other, and one or more hydrogen atoms in the alkyl group are each independently optionally replaced with halogen or an alkyl group of 1 to 17 carbon atoms);
A4 and A7 are each independently hydrogen, halogen, or an alkyl group of 1 to 10 carbon atoms (where one or more methylene groups in the alkyl group are each independently optionally replaced with oxygen, —CO—, —COO—, or —OCO— such that no oxygen atoms are directly linked to each other, and one or more hydrogen atoms in the alkyl group are each independently optionally replaced with halogen or an alkyl group of 1 to 9 carbon atoms);
p is 1 to 10; and
B1, B2, and B3 are each independently hydrogen or a linear or branched alkyl group of 1 to 10 carbon atoms (where one or more methylene groups in the alkyl group are each independently optionally replaced with oxygen, —CO—, —COO—, or —OCO— such that no oxygen atoms are directly linked to each other, and one or more hydrogen atoms in the alkyl group are each independently optionally replaced with halogen or a trialkoxysilyl group of 3 to 6 carbon atoms.
Other specific polymerizable compounds represented by general formula (VI) include compounds represented by general formula (X1b).
In the formula,
A8 is hydrogen or methyl; and
the six-membered rings, T1, T2, and T3, are each independently any of the following structures.
In the structures, q is an integer of 1 to 4.
In general formula (X1b) above,
q is 0 or 1;
Y1 and Y2 are each independently a single bond, —CH2CH2—, —CH2O—, —OCH2—, —COO—, —OCO—, —C≡C—, —CH═CH—, —CF═CF—, —(CH2)4—, —CH2CH2CH2O—, —OCH2CH2CH2—, —CH2═CHCH2CH2—, or —CH2CH2CH═CH—;
Y3 is a single bond, —COO—, or —OCO—; and
B8 is a hydrocarbyl group of 1 to 18 carbon atoms.
Still other specific polymerizable compounds represented by general formula (VI) include compounds represented by general formula (X1c).
In the formula, R70 is hydrogen or methyl, and R71 is a hydrocarbyl group having a fused ring.
Among reactive-group-containing polymerizable compounds, preferred polyfunctional reactive-group-containing polymerizable compounds include polymerizable compounds represented by general formula (V) below.
In the formula, X1 and X2 are each independently hydrogen or methyl; Sp1 and Sp2 are each independently a single bond, an alkylene group of 1 to 8 carbon atoms, or —O—(CH2)s— (where s is an integer of 2 to 7, and the oxygen atom is linked to the aromatic ring); U is a linear or branched polyvalent alkylene group of 2 to 20 carbon atoms or a polyvalent cyclic substituent of 5 to 30 carbon atoms, where the alkylene group in the polyvalent alkylene group is optionally substituted with oxygen such that no oxygen atoms are adjacent to each other and is optionally substituted with an alkyl group of 5 to 20 carbon atoms (where the alkylene group in the group is optionally substituted with oxygen such that no oxygen atoms are adjacent to each other) or a cyclic substituent; and k is an integer of 1 to 5.
Although X1 and X2 in general formula (V) above are each independently hydrogen or methyl, X1 and X2 are preferably hydrogen if it is desirable to achieve a higher reaction rate and are preferably methyl if it is desirable to achieve a lower residual monomer content.
Although Sp1 and Sp2 in general formula (V) above are each independently a single bond, an alkylene group of 1 to 8 carbon atoms, or —O—(CH2)s— (where s is an integer of 2 to 7, and the oxygen atom is linked to the aromatic ring), shorter carbon chains are preferred. Specifically, Sp1 and Sp2 are preferably a single bond or an alkylene group of 1 to 5 carbon atoms, more preferably a single bond or an alkylene group of 1 to 3 carbon atoms. If Sp1 and Sp2 are —O—(CH2)s—, s is preferably 1 to 5, more preferably 1 to 3. More preferably, at least one of Sp1 and Sp2 is a single bond, and even more preferably, both of them are single bonds.
Although U in general formula (V) above is a linear or branched polyvalent alkylene group of 2 to 20 carbon atoms or a polyvalent cyclic substituent of 5 to 30 carbon atoms, the alkylene group in the polyvalent alkylene group may optionally be substituted with oxygen such that no oxygen atoms are adjacent to each other and may optionally be substituted with an alkyl group of 5 to 20 carbon atoms (where the alkylene group in the group is optionally substituted with oxygen such that no oxygen atoms are adjacent to each other) or a cyclic substituent, preferably with two or more cyclic substituents.
Specifically, U in general formula (V) above is preferably any of formulas (Va-1) to (Va-5) below, more preferably any of formulas (Va-1) to (Va-3), even more preferably formula (Va-1).
In the formulas, both ends are linked to Sp1 and Sp2.
If U has a cyclic structure, it is preferred that at least one of Sp1 and Sp2 be a single bond, and it is also preferred that both be single bonds.
Although k in general formula (V) above is an integer of 1 to 5, difunctional compounds, where k is 1, and trifunctional compounds, where k is 2, are preferred, and difunctional compounds are more preferred.
Specific preferred compounds represented by general formula (V) above include compounds represented by general formula (Vb) below.
In the formula, X1 and X2 are each independently hydrogen or methyl; Sp1 and Sp2 are each independently a single bond, an alkylene group of 1 to 8 carbon atoms, or —O—(CH2)s— (where s is an integer of 2 to 7, and the oxygen atom is linked to the aromatic ring); Z1 is —OCH2—, —CH2O—, —COO—, —OCO—, —CF2O—, —OCF2—, —CH2CH2—, —CF2CF2—, —CH═CH—COO—, —CH═CH—OCO—, —COO—CH═CH—, —OCO—CH═CH—, —COO—CH2CH2—, —OCO—CH2CH2—, —CH2CH2—COO—, —CH2CH2—OCO—, —COO—CH2—, —OCO—CH2—, —CH2—COO—, —CH2—OCO—, —CY1═CY2—, —C≡C—, or a single bond; and C is 1,4-phenylene, trans-1,4-cyclohexylene, or a single bond. Any hydrogen atom in any 1,4-phenylene group in the formula is optionally replaced with fluorine.
Although X1 and X2 in general formula (Vb) above are each independently hydrogen or methyl, diacrylate derivatives, where both X1 and X2 are hydrogen, and dimethacrylate derivatives, where both X1 and X2 are methyl, are preferred. Also preferred are compounds where one of X1 and X2 is hydrogen and the other is methyl. Among these compounds, diacrylate derivatives have the highest rates of polymerization, dimethacrylate derivatives have the lowest rates of polymerization, and asymmetrical compounds have intermediate rates of polymerization. Any suitable compound may be used depending on the application. In particular, dimethacrylate derivatives are preferred for PSA liquid crystal display devices.
Although Sp1 and Sp2 in general formula (Vb) above are each independently a single bond, an alkylene group of 1 to 8 carbon atoms, or —O—(CH2)s—, compounds where at least one of Sp1 and Sp2 is a single bond are preferred for PSA liquid crystal display devices. Specifically, compounds where both of Sp1 and Sp2 are single bonds and compounds where one of Sp1 and Sp2 is a single bond and the other is an alkylene group of 1 to 8 carbon atoms or —O—(CH2)s— are preferred. In this case, an alkylene group of 1 to 4 carbon atoms is preferred, and s is preferably 1 to 4.
Although Z1 in general formula (Vb) above is —OCH2—, —CH2O—, —COO—, —OCO—, —CF2O—, —OCF2—, —CH2CH2—, —CF2CF2—, —CH═CH—COO—, —CH═CH—OCO—, —COO—CH═CH—, —OCO—CH═CH—, —COO—CH2CH2—, —OCO—CH2CH2—, —CH2CH2—COO—, —CH2CH2—OCO—, —COO—CH2—, —OCO—CH2—, —CH2—COO—, —CH2—OCO—, —CY1═CY2—, or a single bond, Z1 is preferably —OCH2—, —CH2O—, —COO—, —OCO—, —CF2O—, —OCF2—, —CH2CH2—, —CF2CF2—, or a single bond, more preferably —COO—, —OCO—, or a single bond, even more preferably a single bond.
Although C in general formula (Vb) above is 1,4-phenylene or trans-1,4-cyclohexylene where any hydrogen atom is optionally replaced with fluorine, or a single bond, C is preferably 1,4-phenylene or a single bond. If C is a cyclic structure, rather than a single bond, Z1 is also preferably a linking group other than a single bond. If C is a single bond, Z1 is preferably a single bond.
As discussed above, C in general formula (Vb) above is preferably a single bond, and the cyclic structure is preferably composed of two rings. Specific preferred polymerizable compounds having a cyclic structure include compounds represented by general formulas (V-1) to (V-6) below, more preferably compounds represented by general formulas (V-1) to (V-4), most preferably a compound represented by general formula (V-2).
Other specific preferred compounds represented by general formula (V) above include compounds represented by general formula (Vc) below.
In the formula, X1, X2, and X3 are each independently hydrogen or methyl; Sp1, Sp2, and Sp3 are each independently a single bond, an alkylene group of 1 to 8 carbon atoms, or —O—(CH2)s— (where s is an integer of 2 to 7, and the oxygen atom is linked to the aromatic ring); Z11 and Z12 are each independently —OCH2—, —CH2O—, —COO—, —OCO—, —CF2O—, —OCF2—, —CH2CH2—, —CF2CF2—, —CH═CH—COO—, —CH═CH—OCO—, —COO—CH═CH—, —OCO—CH═CH—, —COO—CH2CH2—, —OCO—CH2CH2—, —CH2CH2—COO—, —CH2CH2—OCO—, —COO—CH2—, —OCO—CH2—, —CH2—COO—, —CH2—OCO—, —CY1═CY2—, —C≡C—, or a single bond; and J is 1,4-phenylene, trans-1,4-cyclohexylene, or a single bond. Any hydrogen atom in any 1,4-phenylene group in the formula is optionally replaced with fluorine.
If a polymerizable monomer is added, polymerization proceeds without the use of a polymerization initiator; however, a polymerization initiator may be added to promote the polymerization. Examples of polymerization initiators include benzoin ethers, benzophenones, acetophenones, benzyl ketals, and acylphosphine oxides. A stabilizer may also be added to improve storage stability. Examples of stabilizers that can be used include hydroquinones, hydroquinone monoalkyl ethers, tert-butylcatechols, pyrogallols, thiophenols, nitro compounds, β-naphthylamines, β-naphthols, and nitroso compounds.
A liquid crystal layer containing a polymerizable monomer is useful in liquid crystal display devices, particularly active-matrix-driven liquid crystal display devices, including PSA, PSVA, VA, IPS, and ECB liquid crystal display devices.
A liquid crystal layer containing a polymerizable monomer acquires the ability to align liquid crystal molecules when the polymerizable monomer present therein is polymerized by exposure to ultraviolet radiation. The liquid crystal layer is used in a liquid crystal display device that controls the intensity of transmitted light by means of the birefringence of the liquid crystal composition.
As discussed above, liquid crystal display devices including oxide semiconductor thin-film transistors have the problem of the diffusion of oxygen desorbed from the oxide semiconductor layer 113 into the insulating layer 118 covering the oxide semiconductor layer 113. As shown in
However, the use of a particular liquid crystal composition in the liquid crystal display device according to the present invention reduces the influence of the interaction between the oxide semiconductor layer and the liquid crystal composition. The liquid crystal display device according to the present invention does not exhibit a significant decrease in voltage holding ratio (VHR) or increase in ion density (ID) of the liquid crystal layer and thus does not suffer from display defects such as white spots, uneven alignment, and image-sticking and also consumes less power.
A liquid crystal display device according to a second embodiment of the present invention includes oxide semiconductor thin-film transistors and a particular liquid crystal composition and generates an electric field containing a component parallel to the substrate surface. The liquid crystal display device according to the second preferred embodiment is an in-plane switching (IPS) liquid crystal display device or a fringe-field switching (FFS) liquid crystal display device, which is a type of IPS liquid crystal display device.
An IPS liquid crystal display device according to the second preferred embodiment of the present invention preferably includes first and second opposing substrates, a liquid crystal layer containing a liquid crystal composition between the first and second substrates, a plurality of gate lines and data lines arranged in a matrix on the first substrate, thin-film transistors disposed at intersections of the gate lines and the data lines, and pixel electrodes that are driven by the transistors and that are made of a transparent conductive material. Each thin-film transistor preferably includes a gate electrode, an oxide semiconductor layer disposed over the gate electrode with an insulating layer therebetween, and source and drain electrodes electrically connected to the oxide semiconductor layer. The thin-film transistors are preferably disposed at the intersections of the gate lines and the data lines. The pixel electrodes are preferably connected to the thin-film transistors. The liquid crystal display device preferably further includes common electrodes disposed on the first or second substrate and separated from the pixel electrodes and alignment layers that are disposed between the first and second substrates and the liquid crystal layer and close to the liquid crystal layer and that induce homogeneous alignment to the liquid crystal composition. The first and second substrates are preferably transparent insulating substrates. The pixel electrodes and the common electrodes are preferably arranged such that the shortest path from the pixel electrodes to the common electrodes located close to the pixel electrodes contains a component parallel to the first or second substrate.
By “the shortest path from the pixel electrodes to the common electrodes located close to the pixel electrodes contains a component parallel to the first or second substrate”, it is meant that the direction vector indicating the shortest path from the pixel electrodes to the common electrodes located closest to the pixel electrodes contains a component parallel to the first or second substrate. For example, if the pixel electrodes and the counter electrodes overlap each other in the direction perpendicular to the first or second substrate, the shortest path from the pixel electrodes to the common electrodes located close to the pixel electrodes is perpendicular to the first or second substrate; therefore, it contains no component parallel to the first or second substrate. That is, the pixel electrodes and the counter electrodes are arranged such that they do not overlap each other in the direction perpendicular to the first or second substrate. The counter electrodes may be disposed either on the first substrate or on the second substrate.
Since the common electrodes and the pixel electrodes are separated such that they do not overlap each other in the direction perpendicular to the first or second substrate, an electric field (E) containing a planar component can be generated between the common electrodes and the pixel electrodes. For example, if alignment layers are used that induce homogeneous alignment to the liquid crystal composition, the liquid crystal molecules are aligned in the alignment direction of the alignment layers, i.e., in the planar direction, thereby blocking light, before a voltage is applied across the common electrodes and the pixel electrodes. When a voltage is applied, the liquid crystal molecules are rotated horizontally relative to the substrate by the planar electric field (E) and are aligned in the electric field direction, thereby transmitting light.
An FFS liquid crystal display device according to the second preferred embodiment of the present invention preferably includes first and second opposing substrates, a liquid crystal layer containing a liquid crystal composition between the first and second substrates, a plurality of gate lines and data lines arranged in a matrix on the first substrate, thin-film transistors disposed at intersections of the gate lines and the data lines, and pixel electrodes that are driven by the transistors and that are made of a transparent conductive material. Each thin-film transistor preferably includes a gate electrode, an oxide semiconductor layer disposed over the gate electrode with an insulating layer therebetween, and source and drain electrodes electrically connected to the oxide semiconductor layer. The liquid crystal display device preferably further includes common electrodes disposed on the first substrate and separated from the pixel electrodes and alignment layers that are disposed between the first and second substrates and the liquid crystal layer and close to the liquid crystal layer and that induce homogeneous alignment to the liquid crystal composition. The first and second substrates are preferably transparent insulating substrates. The pixel electrodes and the common electrodes are preferably arranged such that the shortest distance d between the common electrodes and the pixel electrodes located close to each other is shorter than the shortest distance G between the alignment layers.
As used herein, the term “IPS liquid crystal display device” refers to a liquid crystal display device in which the shortest distance d between the common electrodes and the pixel electrodes is longer than the shortest distance G between the alignment layers, whereas the term “FFS liquid crystal display device” refers to a liquid crystal display device in which the shortest distance d between the common electrodes and the pixel electrodes located close to each other is shorter than the shortest distance G between the alignment layers. The only requirement for FFS is that the shortest distance d between the common electrodes and the pixel electrodes located close to each other is shorter than the shortest distance G between the alignment layers; therefore, there may be any positional relationship between the surfaces of the common electrodes and the pixel electrodes in the thickness direction. Example FSS liquid crystal display devices according to the present invention include those in which the pixel electrodes are disposed closer to the liquid crystal layer than are the common electrodes, as shown in
An example FFS liquid crystal display device according to the second embodiment of the present invention will now be described with reference to
The FFS liquid crystal display device utilizes a fringe field, which is formed between the common electrodes and the pixel electrodes since the shortest distance d between the common electrodes and the pixel electrodes located close to each other is shorter than the shortest distance G between the alignment layers. This allows horizontal alignment and vertical alignment of liquid crystal molecules to be efficiently utilized. Specifically, the FFS liquid crystal display device can utilize a horizontal electric field perpendicular to the lines forming the comb-shaped pattern of pixel electrodes 21 and a parabolic electric field.
For the FFS liquid crystal display device, in which the shortest distance d between the common electrodes and the pixel electrodes located close to each other is shorter than the shortest distance G between the alignment layers, as shown in
The rubbing direction of the alignment layers 4 in the second embodiment is preferably selected such that the major axes of the liquid crystal molecules are aligned at an angle θ of about 0° to 45° with respect to the x-axis, which is the direction perpendicular to the lines forming the comb-shaped pattern of the pixel electrodes 21 (the direction in which the horizontal electric field is formed). The liquid crystal composition used in the second embodiment is of the same type the liquid crystal composition described in the first embodiment, i.e., a liquid crystal composition with negative dielectric anisotropy. When no voltage is applied, the liquid crystal molecules are aligned such that the major axes thereof are parallel to the alignment direction of the alignment layers 4. When a voltage is applied, the liquid crystal molecules, which have negative dielectric anisotropy, are rotated such that the major axes thereof are perpendicular to the direction of the resulting electric field. Although the liquid crystal molecules located near the pixel electrodes 21 are subject to the fringe field, they are not rotated such that the major axes thereof are perpendicular to the alignment layers 4 since liquid crystal molecules with negative dielectric anisotropy are polarized along the minor axes of the molecules; therefore, the major axes of all liquid crystal molecules 30 in the liquid crystal layer 5 can be maintained parallel to the alignment layers 4. Thus, the FFS liquid crystal display device including liquid crystal molecules with negative dielectric anisotropy has superior transmittance characteristics.
In
As shown in
The FFS liquid crystal display device, which utilizes a fringe field, may have any configuration in which the shortest distance d between the common electrodes and the pixel electrodes located close to each other is shorter than the shortest distance G between the alignment layers. For example, as shown in
The thin-film transistors shown in
The insulating layer 18 of the thin-film transistors shown in
The first substrate 2, second substrate 7, transparent electrode 6, color filter 6, alignment layers 4, and liquid crystal layer 5 of the FFS liquid crystal display device shown in
As shown in
However, the use of a particular liquid crystal composition in the liquid crystal display device according to the present invention reduces the influence of the interaction between the oxide semiconductor layer and the liquid crystal composition. The liquid crystal display device according to the present invention does not exhibit a significant decrease in voltage holding ratio (VHR) or increase in ion density (ID) of the liquid crystal layer and thus does not suffer from display defects such as white spots, uneven alignment, and image-sticking and also consumes less power.
A liquid crystal display device according to a third embodiment of the present invention includes oxide semiconductor thin-film transistors and a particular liquid crystal composition. The liquid crystal display device preferably includes color filters 6 formed on the same substrate as the electrode layer 3 including the thin-film transistors, i.e., on the first substrate. This structure is commonly known as color-filter-on-array (COA). Specific structures will now be described with reference to
The liquid crystal display device has a rectangular display area located in the center thereof and a rectangular non-display area extending around the periphery of the display area. Red, green, and blue color filters are formed in the display area. More specifically, the peripheries of the color filters overlap signal lines (such as data lines and gate lines).
The pixel electrodes 21, which are made of a transparent conductive film such as ITO film, are disposed on the color filters. The individual pixel electrodes 21 are connected to the corresponding thin-film transistors via through-holes (not shown) formed in the insulating layer 18 and the color layers. More specifically, the pixel electrodes 21 are connected to the thin-film transistors via the contact electrodes described above. A plurality of spacers (not shown) such as pillars may be disposed on the pixel electrodes 21. The alignment layer 4 is formed on the color filters and the pixel electrodes 21.
Other members such as the oxide semiconductor layer and the liquid crystal layer in the third embodiment are similar to those in the first and second embodiments and are therefore not described herein.
The liquid crystal display devices according to the present invention can be used in combination with backlights for various applications, including liquid crystal display televisions, personal computer monitors, cellular phone and smartphone displays, notebook personal computers, portable information terminals, and digital signage. Examples of backlights include cold cathode fluorescent lamp backlights and two-peak-wavelength and three-peak-wavelength pseudo-white backlights including inorganic light-emitting diodes and organic EL devices.
Some of the most preferred embodiments of the present invention are illustrated by the following examples, although these examples are not intended to limit the invention. The percentages for the compositions of the following Examples and Comparative Examples are by mass.
The properties measured in the examples are as follows:
Tni: nematic phase-isotropic liquid phase transition temperature (° C.)
Δn: refractive index anisotropy at 25° C.
Δ∈: dielectric anisotropy at 25° C.
η: viscosity (mPa·s) at 20° C.
γ1: rotational viscosity (mPa·s) at 25° C.
dgap: cell gap (μm) between first and second substrates
VHR: voltage holding ratio (%) at 70° C. (the percentage of the voltage measured on a cell having a cell thickness of 3.5 μm and filled with a liquid crystal composition at an applied voltage of 5 V, a frame time of 200 ms, and a pulse duration of 64 μs, to the initial applied voltage)
ID: ion density (pC/cm2) at 70° C. (the ion density measured on a cell having a cell thickness of 3.5 μm and filled with a liquid crystal composition at an applied voltage of 20 V and a frequency of 0.05 Hz using an MTR-1 measurement system (Toyo Corporation))
Each liquid crystal display device was evaluated for image-sticking as follows. After a predetermined fixed pattern was displayed within the display area for 1,000 hours, a uniform image was displayed over the entire screen and was visually inspected for image-sticking of the fixed pattern. The liquid crystal display device was rated on the following four-level scale:
A: no image-sticking
B: slight and acceptable image-sticking
C: unacceptable image-sticking
D: severe image-sticking
The transmittance of each liquid crystal display device is expressed as the percentage of the transmittance of the device after the injection of the liquid crystal composition to the transmittance of the device before the injection of the liquid crystal composition.
-n: —CnH2n+1 linear alkyl group of n carbon atoms
n-: CnH2n+1— linear alkyl group of n carbon atoms
—On: —OCnH2n+1 linear alkoxy group of n carbon atoms
nO—: CnH2n+1O— linear alkoxy group of n carbon atoms
—V: —CH═CH2
V—: CH2═CH—
—V1: —CH═CH—CH3
1V—: CH3—CH═CH—
-2V: —CH2—CH2—CH═CH3
V2-: CH3═CH—CH2—CH2—
-2V1: —CH2—CH2—CH═CH—CH3
1V2-: CH3—CH═CH—CH2—CH2
0d3-: CH2═CH—CH2—CH2—
-3d0: —CH2—CH2—CH═CH2
—VO—: —COO—
-T-: —C≡C—
—N—: —CH═N—N═CH—
Thin-film transistors including an In—Ga—Zn oxide film as shown in
Liquid Crystal Composition 1 was found to have a liquid crystal layer temperature limit of 81° C., which is practical for televisions, a large absolute value of dielectric anisotropy, a low viscosity, and an optimal Δn.
The liquid crystal display device of Example 1 had a high VHR, a low ID, and a high transmittance. The liquid crystal display device also exhibited no or only slight and acceptable image-sticking.
Liquid Crystal Compositions 2 and 3 shown in the following tables were injected as in Example 1 to obtain liquid crystal display devices of Examples 2 and 3. The resulting liquid crystal display devices were tested for VHR, ID, and transmittance and were evaluated for image-sticking. The following tables summarize the composition and physical properties of the liquid crystal compositions, the VHR, ID, and transmittance of the liquid crystal display devices, and the results of the image-sticking evaluation.
The liquid crystal display devices of Examples 2 and 3 had high VHRs, low IDs, and high transmittances. These liquid crystal display devices also exhibited no or only slight and acceptable image-sticking.
Liquid Crystal Compositions 4 to 6 shown in the following tables were injected as in Example 1 to obtain liquid crystal display devices of Examples 4 to 6. The resulting liquid crystal display devices were tested for VHR and ID and were evaluated for image-sticking. The following tables summarize the composition and physical properties of the liquid crystal compositions, the VHR and ID of the liquid crystal display devices, and the results of the image-sticking evaluation.
The liquid crystal display devices of Examples 4 to 6 had high VHRs and low IDs. These liquid crystal display devices also exhibited no or only slight and acceptable image-sticking.
Liquid Crystal Compositions 7 to 9 shown in the following tables were injected as in Example 1 to obtain liquid crystal display devices of Examples 7 to 9. The resulting liquid crystal display devices were tested for VHR and ID and were evaluated for image-sticking. The following tables summarize the composition and physical properties of the liquid crystal compositions, the VHR and ID of the liquid crystal display devices, and the results of the image-sticking evaluation.
The liquid crystal display devices of Examples 7 to 9 had high VHRs and low IDs. These liquid crystal display devices also exhibited no or only slight and acceptable image-sticking.
Liquid Crystal Compositions 10 to 12 shown in the following tables were injected as in Example 1 to obtain liquid crystal display devices of Examples 10 to 12. The resulting liquid crystal display devices were tested for VHR and ID and were evaluated for image-sticking. The following tables summarize the composition and physical properties of the liquid crystal compositions, the VHR and ID of the liquid crystal display devices, and the results of the image-sticking evaluation.
The liquid crystal display devices of Examples 10 to 12 had high VHRs and low IDs. These liquid crystal display devices also exhibited no or only slight and acceptable image-sticking.
Liquid Crystal Compositions 13 to 15 shown in the following tables were injected as in Example 1 to obtain liquid crystal display devices of Examples 13 to 15. The resulting liquid crystal display devices were tested for VHR and ID and were evaluated for image-sticking. The following tables summarize the composition and physical properties of the liquid crystal compositions, the VHR and ID of the liquid crystal display devices, and the results of the image-sticking evaluation.
The liquid crystal display devices of Examples 13 to 15 had high VHRs and low IDs. These liquid crystal display devices also exhibited no or only slight and acceptable image-sticking.
Liquid Crystal Compositions 16 to 18 shown in the following tables were injected as in Example 1 to obtain liquid crystal display devices of Examples 16 to 18. The resulting liquid crystal display devices were tested for VHR and ID and were evaluated for image-sticking. The following tables summarize the composition and physical properties of the liquid crystal compositions, the VHR and ID of the liquid crystal display devices, and the results of the image-sticking evaluation.
The liquid crystal display devices of Examples 16 to 18 had high VHRs and low IDs. These liquid crystal display devices also exhibited no or only slight and acceptable image-sticking.
Liquid Crystal Compositions 19 to 21 shown in the following tables were injected as in Example 1 to obtain liquid crystal display devices of Examples 19 to 21. The resulting liquid crystal display devices were tested for VHR and ID and were evaluated for image-sticking. The following tables summarize the composition and physical properties of the liquid crystal compositions, the VHR and ID of the liquid crystal display devices, and the results of the image-sticking evaluation.
The liquid crystal display devices of Examples 19 to 21 had high VHRs and low IDs. These liquid crystal display devices also exhibited no or only slight and acceptable image-sticking.
Liquid Crystal Compositions 22 to 24 shown in the following tables were injected as in Example 1 to obtain liquid crystal display devices of Examples 22 to 24. The resulting liquid crystal display devices were tested for VHR and ID and were evaluated for image-sticking. The following tables summarize the composition and physical properties of the liquid crystal compositions, the VHR and ID of the liquid crystal display devices, and the results of the image-sticking evaluation.
The liquid crystal display devices of Examples 22 to 24 had high VHRs and low IDs. These liquid crystal display devices also exhibited no or only slight and acceptable image-sticking.
Liquid Crystal Compositions 25 to 27 shown in the following tables were injected as in Example 1 to obtain liquid crystal display devices of Examples 25 to 27. The resulting liquid crystal display devices were tested for VHR and ID and were evaluated for image-sticking. The following tables summarize the composition and physical properties of the liquid crystal compositions, the VHR and ID of the liquid crystal display devices, and the results of the image-sticking evaluation.
The liquid crystal display devices of Examples 25 to 27 had high VHRs and low IDs. These liquid crystal display devices also exhibited no or only slight and acceptable image-sticking.
Liquid Crystal Composition 1 was mixed with 0.3% by mass of 4-{2-[4-(2-acryloyloxy-ethyl)-phenoxycarbonyl]-ethyl}-biphenyl-4′-yl 2-methyl-acrylate to obtain Liquid Crystal Composition 28. Liquid Crystal Composition 28 was injected into a VA cell as used in Example 1 and was polymerized by exposing the liquid crystal composition to ultraviolet radiation for 600 seconds (3.0 J/cm2) while applying a drive voltage across the electrodes to obtain a liquid crystal display device of Example 28. The resulting liquid crystal display device was tested for VHR and ID and was evaluated for image-sticking. The following table summarizes the composition and physical properties of the liquid crystal composition, the VHR and ID of the liquid crystal display device, and the results of the image-sticking evaluation.
The liquid crystal display device of Example 28 had a high VHR and a low ID. The liquid crystal display device also exhibited no or only slight and acceptable image-sticking.
Liquid Crystal Composition 13 was mixed with 0.3% by mass of biphenyl-4,4′-diyl bismethacrylate to obtain Liquid Crystal Composition 29. Liquid Crystal Composition 28 was injected into a VA cell as used in Example 1 and was polymerized by exposing the liquid crystal composition to ultraviolet radiation for 600 seconds (3.0 J/cm2) while applying a drive voltage across the electrodes to obtain a liquid crystal display device of Example 29. The resulting liquid crystal display device was tested for VHR and ID and was evaluated for image-sticking. The following table summarizes the composition and physical properties of the liquid crystal composition, the VHR and ID of the liquid crystal display device, and the results of the image-sticking evaluation.
The liquid crystal display device of Example 29 had a high VHR and a low ID. The liquid crystal display device also exhibited no or only slight and acceptable image-sticking.
Liquid Crystal Composition 19 was mixed with 0.3% by mass of 3-fluorobiphenyl-4,4′-diyl bismethacrylate to obtain Liquid Crystal Composition 30. Liquid Crystal Composition 28 was injected into a VA cell as used in Example 1 and was polymerized by exposing the liquid crystal composition to ultraviolet radiation for 600 seconds (3.0 J/cm2) while applying a drive voltage across the electrodes to obtain a liquid crystal display device of Example 28. The resulting liquid crystal display device was tested for VHR and ID and was evaluated for image-sticking. The following table summarizes the composition and physical properties of the liquid crystal composition, the VHR and ID of the liquid crystal display device, and the results of the image-sticking evaluation.
The liquid crystal display device of Example 30 had a high VHR and a low ID. The liquid crystal display device also exhibited no or only slight and acceptable image-sticking.
Liquid Crystal Compositions 31 to 33 shown in the following tables were injected as in Example 1 to obtain liquid crystal display devices of Examples 31 to 33. The resulting liquid crystal display devices were tested for VHR and ID and were evaluated for image-sticking. The following tables summarize the composition and physical properties of the liquid crystal compositions, the VHR and ID of the liquid crystal display devices, and the results of the image-sticking evaluation.
Although the liquid crystal display devices of Examples 31 to 33 had high IDs, they exhibited only slight and acceptable image-sticking.
Liquid Crystal Compositions 34 to 36 shown in the following tables were injected as in Example 1 to obtain liquid crystal display devices of Examples 34 to 36. The resulting liquid crystal display devices were tested for VHR and ID and were evaluated for image-sticking. The following tables summarize the composition and physical properties of the liquid crystal compositions, the VHR and ID of the liquid crystal display devices, and the results of the image-sticking evaluation.
Although the liquid crystal display devices of Examples 34 to 36 had high IDs, they exhibited only slight and acceptable image-sticking.
Liquid Crystal Compositions 37 and 38 shown in the following tables were injected as in Example 1 to obtain liquid crystal display devices of Examples 37 and 38. The resulting liquid crystal display devices were tested for VHR and ID and were evaluated for image-sticking. The following tables summarize the composition and physical properties of the liquid crystal compositions, the VHR and ID of the liquid crystal display devices, and the results of the image-sticking evaluation.
Although the liquid crystal display devices of Examples 37 and 38 had high IDs, they exhibited only slight and acceptable image-sticking.
Liquid Crystal Compositions 39 to 41 shown in the following tables were injected as in Example 1 to obtain liquid crystal display devices of Examples 39 to 41. The resulting liquid crystal display devices were tested for VHR and ID and were evaluated for image-sticking. The following tables summarize the composition and physical properties of the liquid crystal compositions, the VHR and ID of the liquid crystal display devices, and the results of the image-sticking evaluation.
Although the liquid crystal display devices of Examples 39 to 41 had high IDs, they exhibited only slight and acceptable image-sticking.
Liquid Crystal Composition 45 shown in the following table was injected as in Example 1 to obtain a liquid crystal display device of Example 45. The resulting liquid crystal display device was tested for VHR and ID and was evaluated for image-sticking. The following tables summarize the composition and physical properties of the liquid crystal composition, the VHR and ID of the liquid crystal display device, and the results of the image-sticking evaluation.
Although the liquid crystal display device of Example 42 had a high ID, it exhibited only slight and acceptable image-sticking.
Comparative Liquid Crystal Composition 1 shown in the following table was injected as in Example 1 to obtain a liquid crystal display device of Comparative Example 1. The resulting liquid crystal display device was tested for VHR and ID and was evaluated for image-sticking. The liquid crystal display device of Comparative Example 1 was also tested for transmittance.
The following tables summarize the composition and physical properties of the liquid crystal composition, the VHR, ID, and transmittance of the liquid crystal display device, and the results of the image-sticking evaluation.
Comparative Liquid Crystal Compositions 2 to 5 shown in the following tables were injected as in Example 1 to obtain liquid crystal display devices of Comparative Examples 2 to 5. The resulting liquid crystal display devices were tested for VHR and ID and were evaluated for image-sticking. The results are summarized in the following tables.
The procedures of Examples 1, 2, 8, 13, 14, 19, 20, and 26 were repeated except that the In—Ga—Zn oxide film was replaced with an amorphous silicon film to obtain liquid crystal display devices of Comparative Examples 5 to 12. The resulting liquid crystal display devices were tested for VHR and ID and were evaluated for image-sticking. The liquid crystal display devices of Comparative Examples 16 and 17 were also tested for transmittance. The results are summarized in the following tables.
The liquid crystal display devices of Comparative Examples 5 to 12 had high VHRs and low IDs and also exhibited no or only slight and acceptable image-sticking. These liquid crystal display devices, however, had lower transmittances than the liquid crystal display devices of Examples 1 and 2, which had a thin-film transistor layer including an In—Ga—Zn oxide film.
An electrode structure was formed on at least one of first and second substrates. Horizontal alignment layers were formed on the opposing surfaces of the first and second substrates and were subjected to weak rubbing. FFS cells were assembled, and Liquid Crystal Compositions 43 to 35 shown in the following tables were injected between the first and second substrates to obtain liquid crystal display devices of Comparative Examples 43 to 45 (dgap=3.0 μm, alignment layer: AL-1051) (dgap=3.0 μm).
The liquid crystal display devices of Examples 43 to 45 were tested for VHR, ID, and transmittance and were evaluated for image-sticking. The following tables summarize the composition and physical properties of the liquid crystal compositions, the VHR, ID, and transmittance of the liquid crystal display devices, and the results of the image-sticking evaluation.
The liquid crystal display devices of Examples 43 to 45 had high VHRs, low IDs, and high transmittances. These liquid crystal display devices also exhibited no or only slight and acceptable image-sticking.
Liquid Crystal Compositions 46 and 47 shown in the following tables were injected as in Example 1 to obtain liquid crystal display devices of Examples 46 and 47. The resulting liquid crystal display devices were tested for VHR and ID and were evaluated for image-sticking. The following tables summarize the composition and physical properties of the liquid crystal compositions, the VHR and ID of the liquid crystal display devices, and the results of the image-sticking evaluation.
The liquid crystal display devices of Examples 46 and 47 had high VHRs and low IDs. These liquid crystal display devices also exhibited no or only slight and acceptable image-sticking.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2013-233959 | Nov 2013 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2014/079197 | 11/4/2014 | WO | 00 |
