CN112526788B - Liquid crystal display device having a plurality of pixel electrodes - Google Patents

Liquid crystal display device having a plurality of pixel electrodes Download PDF

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CN112526788B
CN112526788B CN201910876063.6A CN201910876063A CN112526788B CN 112526788 B CN112526788 B CN 112526788B CN 201910876063 A CN201910876063 A CN 201910876063A CN 112526788 B CN112526788 B CN 112526788B
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liquid crystal
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carbon atoms
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CN112526788A (en
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马文阳
王力娜
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Jiangsu Hecheng Display Technology Co Ltd
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    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1341—Filling or closing of cells
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    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K19/00—Liquid crystal materials
    • C09K19/02—Liquid crystal materials characterised by optical, electrical or physical properties of the components, in general
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    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
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    • C09K19/00—Liquid crystal materials
    • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
    • C09K19/38—Polymers
    • C09K19/3833—Polymers with mesogenic groups in the side chain
    • C09K19/3842—Polyvinyl derivatives
    • C09K19/3852—Poly(meth)acrylate derivatives
    • C09K19/3857—Poly(meth)acrylate derivatives containing at least one asymmetric carbon atom
    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
    • C09K19/00—Liquid crystal materials
    • C09K19/04—Liquid crystal materials characterised by the chemical structure of the liquid crystal components, e.g. by a specific unit
    • C09K19/42—Mixtures of liquid crystal compounds covered by two or more of the preceding groups C09K19/06 - C09K19/40
    • C09K19/44—Mixtures of liquid crystal compounds covered by two or more of the preceding groups C09K19/06 - C09K19/40 containing compounds with benzene rings directly linked

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Abstract

The invention discloses a liquid crystal display device, which is provided with an upper substrate, a lower substrate and a liquid crystal medium filled between the upper substrate and the lower substrate, wherein the box thickness d of the liquid crystal display device is 2.5-4.5 mu m, and the liquid crystal display device is characterized in that the liquid crystal medium filled between the upper substrate and the lower substrate simultaneously meets the following conditions: (1) Δ n a ·d＜350nm；(2)Δn b D > 290nm; and (3) (Δ n) a ‑Δn b ) D is less than or equal to 40nm, wherein, delta n a The optical anisotropy of the liquid crystal medium at 25 ℃ and under the illumination wavelength of 450 nm; and Δ n b Is the optical anisotropy of the liquid crystal medium at 25 ℃ and 650nm illumination wavelength. According to the invention, the optical anisotropy values of the liquid crystal medium in the liquid crystal display device under different illumination wavelengths and the box thickness of the liquid crystal display device are matched, so that the prepared liquid crystal display device has proper transmittance and can realize good display effect, and the incidence rate of color cast problem is greatly reduced.

Description

Liquid crystal display device having a plurality of pixel electrodes
Technical Field
The invention relates to the field of liquid crystal display, in particular to a liquid crystal display device which simultaneously gives consideration to high transmittance and good color performance.
Background
Liquid Crystal Displays (LCDs) have been rapidly developed due to their small size, light weight, low power consumption and excellent Display quality, and are widely used in portable electronic information products in particular. Types of display modes are classified into PC (phase change), TN (twisted nematic), STN (super twisted nematic), ECB (electrically controlled birefringence), OCB (optically compensated bend), IPS (in-plane switching), FFS (fringe field switching), VA (vertical alignment), and PSA (polymer stable alignment), among which VA type display technologies are widely used particularly due to their high contrast ratio characteristics.
MVA (Multi-domain Vertical Alignment), UV 2 Both A (Ultraviolet induced multi-domain Vertical Alignment) and PSVA (polymer stable Vertical Alignment) are common VA displaysThe mode, and have the following characteristics: under the non-electrified state, the long axis direction of the liquid crystal molecules is vertical to the substrate, after voltage is applied, the liquid crystal molecules deflect, so that the included angle between the liquid crystal molecules and the substrate becomes smaller, different light transmittances can be presented under different included angles, meanwhile, the liquid crystal molecules can also generate different transmittances when the light with different wavelengths irradiates, the change size of the refractive index of the liquid crystal molecules along with the influence of the irradiation wavelength is related, when the difference of the refractive index of the same liquid crystal molecule under the light with different wavelengths is larger, the difference of the transmittances under the light with different wavelengths is larger, and the color cast phenomenon is easier to occur. In addition, the thickness of the liquid crystal layer in a display device also affects the transmittance, and in a certain range, the larger the cell thickness, the larger the transmittance, but the more serious the problem of color shift.
In the prior art, in order to improve the transmittance of a liquid crystal display device, color expression is generally sacrificed, and the two aspects are often contradictory and cannot be solved at the same time. Therefore, there is a need to develop a liquid crystal display device having a suitable transmittance and good color expression.
Disclosure of Invention
The invention aims to: in view of the drawbacks of the prior art, it is an object of the present invention to provide a liquid crystal display device having a proper transmittance and good color expression.
The technical scheme of the invention is as follows:
in order to achieve the above object, the present invention provides a liquid crystal display device having an upper substrate, a lower substrate and a liquid crystal medium filled between the upper substrate and the lower substrate, wherein the cell thickness d of the liquid crystal display device is 2.5 to 4.5 μm, and the liquid crystal medium filled between the upper substrate and the lower substrate is required to satisfy the following conditions:
(1)Δn a ·d＜350nm；
(2)Δn b d > 290nm; and
(3)(Δn a -Δn b )·d≤40nm，
wherein the content of the first and second substances,
Δn a the optical anisotropy of the liquid crystal medium at 25 ℃ and under the illumination wavelength of 450 nm; and is
Δn b Is the optical anisotropy of the liquid crystal medium at 25 ℃ and 650nm illumination wavelength.
The inventors have surprisingly found that when Δ n is equal a When d is more than 350nm, the color expression of the liquid crystal display device is remarkably reduced, and when Δ n b When d is less than 290nm, the transmittance of the liquid crystal display device is significantly reduced.
In some embodiments of the invention, Δ n of the liquid-crystalline medium a And Δ n b Each independently of the other is 0.08 to 0.15.
In some embodiments of the invention, Δ n of the liquid-crystalline medium a ＞Δn b 。
In some embodiments of the invention, | Δ n of the liquid-crystalline medium a -Δn b The | is 0.005-0.015.
The invention can provide a liquid crystal display device which has the advantages of both proper transmittance and good color expression by setting the liquid crystal medium to be a specific composition to match with liquid crystal display devices with different cell thicknesses.
In some embodiments of the invention, the liquid-crystalline medium comprises one or more compounds of the formula M
Figure BDA0002204320340000021
Wherein the content of the first and second substances,
R M1 and R M2 Each independently represents a linear or branched alkyl group having 1 to 12 carbon atoms,
Figure BDA0002204320340000022
Figure BDA0002204320340000023
1 or non-adjacent 2 or more-CH in the linear or branched alkyl containing 1 to 12 carbon atoms 2 -can be respectively and independentlyIs replaced by-CH = CH-, -C ≡ C-, -O-, -CO-O-or-O-CO-;
ring(s)
Figure BDA0002204320340000024
Ring (C)
Figure BDA0002204320340000025
And a ring
Figure BDA0002204320340000026
Each independently represent
Figure BDA0002204320340000027
Or
Figure BDA0002204320340000028
Wherein, the first and the second end of the pipe are connected with each other,
Figure BDA0002204320340000029
one or more-CH of 2 -can be replaced by-O-,
Figure BDA00022043203400000210
at most one-H in (a) may be substituted by halogen;
Z M1 and Z M2 Each independently represents a single bond-CO-O-, -O-CO-, -CH 2 O-、-OCH 2 -、-CH＝CH-、-C≡C-、-CH 2 CH 2 -、-(CH 2 ) 4 -、-CF 2 O-、-OCF 2 -or-CF 2 CF 2 -; and is
n M1 Represents 0, 1, 2 or 3, and when n M1 When =2 or 3, ring
Figure BDA0002204320340000031
May be the same or different, Z M2 May be the same or different.
In some embodiments of the invention, in the compound of formula M, R M1 And R M2 Preferably a linear alkyl group having 1 to 10 carbon atoms and a linear alkoxy group having 1 to 9 carbon atoms, each independentlyA straight chain alkenyl group having 2 to 10 carbon atoms; more preferably, each independently is a linear alkyl group having 1 to 8 carbon atoms, a linear alkoxy group having 1 to 7 carbon atoms, or a linear alkenyl group having 2 to 8 carbon atoms; still more preferably, each of the alkyl groups is a linear alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or an alkenyl group having 2 to 5 carbon atoms.
In some embodiments of the invention, R M1 And R M2 Each of the alkenyl groups is preferably a linear alkenyl group having 2 to 8 carbon atoms, and more preferably a linear alkenyl group having 2 to 5 carbon atoms.
In some embodiments of the invention, preferably, R M1 And R M2 One of the alkyl groups is a linear alkenyl group having 2 to 5 carbon atoms, and the other is a linear alkyl group having 1 to 5 carbon atoms.
In some embodiments of the invention, R M1 And R M2 Preferably a linear alkyl group having 1 to 8 carbon atoms or a linear alkoxy group having 1 to 7 carbon atoms; more preferably, each of the alkyl groups is independently a linear alkyl group having 1 to 5 carbon atoms or a linear alkoxy group having 1 to 4 carbon atoms.
In some embodiments of the invention, preferably, R M1 And R M2 One of the alkyl groups is a linear alkyl group having 1 to 5 carbon atoms, and the other is a linear alkyl group having 1 to 5 carbon atoms or a linear alkoxy group having 1 to 4 carbon atoms; further preferably, R M1 And R M2 Each of which is independently a linear alkyl group having 1 to 5 carbon atoms.
The alkenyl group in the present invention is preferably selected from groups represented by any one of the formulae (V1) to (V9), and particularly preferably formula (V1), formula (V2), formula (V8) or (V9). The groups represented by the formulae (V1) to (V9) are shown below:
Figure BDA0002204320340000032
wherein denotes the carbon atom in the ring structure to which it is bonded.
The alkenyloxy group in the present invention is preferably selected from groups represented by any one of formulae (OV 1) to (OV 9), and particularly preferably formula (OV 1), formula (OV 2), formula (OV 8) or (OV 9). The groups represented by formulae (OV 1) to (OV 9) are as follows:
Figure BDA0002204320340000041
wherein denotes the carbon atom in the ring structure to which it is bonded.
In some embodiments of the invention, the compound of formula M is selected from the group consisting of:
Figure BDA0002204320340000042
Figure BDA0002204320340000051
in some embodiments of the invention, the compound of formula M is preferably selected from the group consisting of compounds of formula M1, formula M2, formula M4 and formula M9.
The lower limit of the preferred content of the compound of formula M is 1%,5%,10%,20%,25%,30%,40% or 50% relative to the total weight of the liquid-crystalline medium of the invention; the upper limit of the preferred content of compounds of the formula M is 70%,65%,60%,55%,45%,35% or 25% relative to the total weight of the liquid-crystalline medium according to the invention.
In order to adjust the performance of the liquid crystal medium in aspects of clearing point, viscosity, low-temperature storage stability and the like, so that the obtained liquid crystal display device has better application value in aspects of transmittance and color expression, the component composition of the liquid crystal medium needs to be adjusted; in particular, in relation to the present inventionTotal weight of liquid crystalline medium, middle ring of formula M
Figure BDA0002204320340000052
To represent
Figure BDA0002204320340000053
The content of the compound (A) is 10-50%; preferably, the ring in formula M
Figure BDA0002204320340000054
To represent
Figure BDA0002204320340000055
The content of the compound (b) is 20-45%.
With regard to the content of the compound of the formula M, when it is desired to keep the viscosity of the liquid-crystalline medium of the invention low and the response time short, it is preferred that the lower limit value is high and the upper limit value is high; further, when the clearing point of the liquid crystal medium of the present invention needs to be kept high and the temperature stability is good, the lower limit value and the upper limit value are preferably high; when the absolute value of the dielectric anisotropy is increased in order to keep the driving voltage low, it is preferable that the lower limit value is lowered and the upper limit value is lowered.
In the case where reliability is important, R is preferable M1 And R M2 Each independently is alkyl; in the case where importance is attached to reduction in volatility of the compound, R is preferably M1 And R M2 Each independently is an alkoxy group; when importance is attached to the reduction in viscosity, R is preferably used M1 And R M2 At least one of which is alkenyl.
In some embodiments of the invention, the liquid-crystalline medium contains one or more R M1 And/or R M2 Compounds of the formula M1 which are n-propyl
Figure BDA0002204320340000061
In some embodiments of the invention, the liquid-crystalline medium further comprises one or more compounds of the formula N
Figure BDA0002204320340000062
Wherein, the first and the second end of the pipe are connected with each other,
R N1 and R N2 Each independently represents a linear or branched alkyl group having 1 to 12 carbon atoms,
Figure BDA0002204320340000063
Figure BDA0002204320340000064
1 or non-adjacent 2 or more-CH in the linear or branched alkyl containing 1 to 12 carbon atoms 2 -may be independently replaced by-CH = CH-, -C ≡ C-, -O-, -CO-O-, or-O-CO-, respectively, and one or more-H present in these groups may be independently substituted by-F or-Cl, respectively;
ring (C)
Figure BDA0002204320340000065
And ring
Figure BDA0002204320340000066
Each independently represent
Figure BDA0002204320340000067
Wherein the content of the first and second substances,
Figure BDA0002204320340000068
one or more-CH of 2 -may be replaced by-O-, one or at most two of the ring bonds in the single bond may be replaced by a double bond,
Figure BDA0002204320340000069
may be substituted with-F or-Cl, and one or more rings-CH = may be replaced with-N =;
Z N1 and Z N2 Each independently represents a single bond-CO-O-, -O-CO-, -CH 2 O-、-OCH 2 -、-CH＝CH-、-C≡C-、-CH 2 CH 2 -、-(CH 2 ) 4 -、-CF 2 O-、-OCF 2 -or-CF 2 CF 2 -；
L N1 And L N2 Each independently represents-H or methyl; and is
n N1 Represents 0, 1, 2 or 3,n N2 Represents 0 or 1, and 0. Ltoreq. N N1 +n N2 Less than or equal to 3, when n is N1 When =2 or 3, a ring
Figure BDA00022043203400000610
May be the same or different, Z N1 May be the same or different.
In some embodiments of the invention, in the compound of formula N, R N1 And R N2 Preferably each independently an alkyl or alkoxy group having 1 to 8 carbon atoms, or an alkenyl or alkenyloxy group having 2 to 8 carbon atoms, and more preferably each independently an alkyl or alkoxy group having 1 to 5 carbon atoms, or an alkenyl or alkenyloxy group having 2 to 5 carbon atoms;
R N1 more preferably an alkyl group having 1 to 5 carbon atoms or an alkenyl group having 2 to 5 carbon atoms, and still more preferably an alkyl group having 2 to 5 carbon atoms or an alkenyl group having 2 to 3 carbon atoms;
R N2 further preferred is an alkoxy group having 1 to 4 carbon atoms;
ring(s)
Figure BDA0002204320340000071
And a ring
Figure BDA0002204320340000072
Preferably, it is
Figure BDA0002204320340000073
Figure BDA0002204320340000074
In some embodiments of the invention, the compound of formula N is selected from the group consisting of:
Figure BDA0002204320340000075
Figure BDA0002204320340000081
Figure BDA0002204320340000091
in some embodiments of the present invention, the compound of formula N is preferably selected from the group consisting of compounds of formula N2, formula N3, formula N5, formula N8 and formula N14.
With respect to the preferred content of the compound of formula N: the lower limit of the preferred content of the compound of the formula N is 0.1%,0.5%,1%,3%,5%,10%,13%,15%,18%,20%,23%,25%,28%,30%,33%,35%,38% or 40%, relative to the total weight of the liquid-crystalline medium of the invention; the upper limit of the preferred content of the compound of the formula N is 75%,72%,70%,68%,65%,63%,60%,55%,50%,40%,38%,35%,33%,30%,28%,25%,23%,20%,18%,15% or 10% relative to the total weight of the liquid-crystalline medium of the invention.
With respect to the preferable content of the compound of the formula N, when it is necessary to keep the response time of the liquid crystal display device of the present invention short, the lower limit value and the upper limit value thereof are preferably low; further, when the liquid crystal display device of the present invention needs to maintain a wider operating temperature range, it is preferable that the lower limit value and the upper limit value are lower; when the absolute value of the dielectric anisotropy is increased in order to keep the driving voltage of the liquid crystal medium low, it is preferable that the lower limit value is increased and the upper limit value is increased.
The liquid crystal medium of the present invention may contain a polymerizable compound for producing a PSVA mode liquid crystal display device. In terms of the polymerization mode, the polymerizable compound to be used may be a photopolymerizable monomer which is polymerized by energy rays such as light; in terms of structure, a polymerizable compound having a liquid crystal skeleton formed by connecting a plurality of six-membered rings, such as a biphenyl derivative or a terphenyl derivative, can be used. Further, the polymerizable compound is preferably a bifunctional monomer of the general formula RM:
Figure BDA0002204320340000092
wherein the content of the first and second substances,
X r1 and X r2 Each independently represents-H or methyl;
Sp 1 and Sp 2 Each independently represents a single bond, - (CH) 2 ) a -or- (CH) 2 ) b O-, wherein a and b each independently represent an integer of 1 to 8, and- (CH) 2 ) b The oxygen atom in O-is attached to an aromatic ring;
Z r1 represents a single bond, -CO-O-) -O-CO-, -CH 2 O-、-OCH 2 -、-CH＝CH-、-C≡C-、-CH 2 CH 2 -、-(CH 2 ) 4 -、-CF 2 O-、-OCF 2 -、-CF 2 CF 2 -、-CH＝CH-CO-O-、-CH＝CH-O-CO-、-CO-O-CH＝CH-、-O-CO-CH＝CH-、-CO-O-CH 2 CH 2 -、-O-CO-CH 2 CH 2 -、-CH 2 CH 2 -CO-O-、-CH 2 CH 2 -O-CO-、-CO-O-CH 2 -、-O-CO-CH 2 -、-CH 2 -CO-O-、-CH 2 -O-CO-, -CH = CF-, -CF = CH-or-CF = CF-;
L r1 and L r2 Each independently represents-F, a linear or branched alkyl or alkoxy group containing 1 to 8 carbon atoms;
ring (C)
Figure BDA0002204320340000101
To represent
Figure BDA0002204320340000102
Wherein
Figure BDA0002204320340000103
May be substituted by-F, straight or branched alkyl or alkoxy containing 1 to 8 carbon atoms;
r1 represents 0 or 1; and is
r2 and r3 each independently represent an integer of 0 to 4.
In some embodiments of the invention, preferably, X r1 And X r2 All represent methyl.
In some embodiments of the invention, preferably Sp 1 And Sp 2 At least one of them represents a single bond; further preferably Sp 1 And Sp 2 All represent single bonds.
In some embodiments of the invention, preferably, Z is r1 Represents a single bond, -CO-O-, -O-CO-; further preferably, Z r1 Represents a single bond.
In some embodiments of the invention, preferably, the ring
Figure BDA0002204320340000104
To represent
Figure BDA0002204320340000105
In some embodiments of the invention, preferably r1 represents 0.
In the formula RM, sp 1 And Sp 2 Preferably the ring structure in between is selected from the group consisting of formula RM-a to RM-e, more preferably from the group consisting of formula RM-a to RM-c, particularly preferably of formula RM-a:
Figure BDA0002204320340000106
Figure BDA0002204320340000111
wherein, two ends of the formulas RM-a to RM-b are respectively connected with Sp 1 Or Sp 2 And (4) connecting.
The polymerizable compound having these skeletons has an alignment regulating force after polymerization that is most suitable for a PSVA liquid crystal display device and can obtain a good alignment state, and thus display unevenness can be suppressed or not generated at all.
In some embodiments of the present invention, the content of the polymerizable compound is preferably 0.01 to 5%, more preferably 0.05 to 3%, and still more preferably 0.1 to 2% with respect to the weight of the liquid crystal medium of the present invention.
In some embodiments of the invention, one or more further additives known to the person skilled in the art and described in the literature may be added to the liquid-crystalline medium.
The stabilizers which can be added to the liquid-crystalline media according to the invention are mentioned below, for example.
Figure BDA0002204320340000112
Figure BDA0002204320340000121
Figure BDA0002204320340000131
Figure BDA0002204320340000141
Preferably, the stabilizer is selected from the stabilizers shown below.
Figure BDA0002204320340000142
In some embodiments of the present invention, preferably, the stabilizer comprises 0 to 5% by weight of the total liquid crystal medium; more preferably, the stabilizer constitutes 0-1% by weight of the total liquid-crystalline medium; particularly preferably, the stabilizer is present in an amount of from 0.01 to 0.1% by weight, based on the total weight of the liquid-crystalline medium.
Has the advantages that:
according to the invention, the optical anisotropy values of the liquid crystal medium in the liquid crystal display device under different illumination wavelengths and the box thickness of the liquid crystal display device are matched, so that the prepared liquid crystal display device has proper transmittance and can realize good display effect, and the incidence rate of color cast problem is greatly reduced.
Detailed Description
The invention will be illustrated below with reference to specific embodiments. It should be noted that the following examples are illustrative of the present invention, and are not intended to limit the present invention. Other combinations and various modifications within the spirit or scope of the present invention may be made without departing from the spirit or scope of the present invention.
In the present invention, the proportions are by weight and all temperatures are in degrees centigrade, unless otherwise specified.
For the sake of convenience of expression, in the following examples, the radical structures of the liquid-crystalline media are represented by the codes listed in Table 1:
TABLE 1 radical structural code of liquid crystal compounds
Figure BDA0002204320340000143
Figure BDA0002204320340000151
Take the example of a compound of the formula:
Figure BDA0002204320340000152
the structural formula is represented by the codes listed in table 1, and can be expressed as follows: nCCGF, wherein n in the code represents the number of C atoms of the left alkyl group, for example, n is "3", i.e., -C 3 H 7 (ii) a In the codeC represents a 1, 4-cyclohexylene group, G represents a 2-fluoro-1, 4-phenylene group, and F represents a fluorine substituent.
The abbreviated codes of the test items in the following examples are as follows:
cp clearing Point (nematic phase-isotropic phase transition temperature,. Degree.C.)
Delta epsilon dielectric anisotropy (1KHz, 25 ℃ C.)
Δn a Optical anisotropy (illumination wavelength 450nm,25 ℃ C.)
Δn b Optical anisotropy (light wavelength 650nm,25 ℃ C.)
T transmittance (%)
Wherein the content of the first and second substances,
Δε＝ε ‖ -ε ⊥ wherein, epsilon ‖ Is the dielectric constant, ε, parallel to the molecular axis ⊥ For the dielectric constant perpendicular to the molecular axis, test conditions: the test box is TN90 type at 25 ℃ and 1KHz, and the thickness of the box is 7 mu m.
Optical anisotropy Δ n a And Δ n b Is measured at 25 ℃ by using Abbe refractometer under light sources of 450nm and 650nm respectively.
Test conditions for transmittance T: the transmittance of the dimmer is tested by using a DMS 505 tester, and the box thickness of the dimmer is 5.2 mu m.
The components used in the following examples can be synthesized by a known method or obtained commercially. These synthesis techniques are conventional and the resulting liquid crystal media are tested to meet the standards for electronic compounds.
The liquid-crystalline media were prepared according to the formulation of the respective liquid-crystalline media specified in the examples below. The liquid-crystalline medium is prepared by conventional methods in the art, such as by mixing in the prescribed proportions by heating, sonication, suspension, and the like.
Bulk liquid Crystal example 1
Nematic Host liquid crystals Host 1 were formulated as in table 2 below.
TABLE 2 composition and Performance parameters of Host 1
Figure BDA0002204320340000161
Bulk liquid Crystal example 2
Nematic Host liquid crystals Host 2 were formulated as in table 3 below.
TABLE 3 composition and Performance parameters of Host 2
Figure BDA0002204320340000162
Figure BDA0002204320340000171
Host liquid Crystal example 3
Nematic Host liquid crystals Host 3 were formulated as in table 4 below.
TABLE 4 composition and Performance parameters of Host 3
Figure BDA0002204320340000172
Host liquid Crystal example 4
Nematic Host liquid crystals Host 4 were formulated as in table 5 below.
TABLE 5 composition and Performance parameters of Host 4
Figure BDA0002204320340000173
Figure BDA0002204320340000181
The VA type liquid crystal display devices of comparative example 1a, example 1 and comparative example 1b according to the present invention were prepared by injecting Host liquid crystal Host 1 into VA type liquid crystal cells having cell thicknesses of 3 μm, 3.5 μm and 4 μm, respectively, by a vacuum injection method, and the observation of color expression and the test of transmittance were performed on the 3 VA type liquid crystal display devices, and the results are shown in the following table 6:
TABLE 6
Comparative example 1a Example 1 Comparative example 1b
Box thickness d (mum) 3 3.5 4
Δn a ·d(nm) 288 336 384
Δn b ·d(nm) 264 308 352
Color representation ◎ ◎ ×
T(％) 6.20 7.00 7.20
Note: x represents a color shift phenomenon, and ∈ represents good color expression.
The VA type liquid crystal display devices of comparative examples 2a, 2 and 2b according to the present invention were manufactured by injecting Host liquid crystal Host 2 into VA type liquid crystal cells having cell thicknesses of 2.8 μm, 3 μm and 3.5 μm by vacuum injection method, respectively, and the observation of color expression and the test of transmittance were performed on the 3 VA type liquid crystal display devices, and the results are shown in the following table 7:
TABLE 7
Comparative example 2a Example 2 Comparative example 2b
Box thickness d (mum) 2.8 3 3.5
Δn a ·d(nm) 308 330 385
Δn b ·d(nm) 272 291 340
Color representation ◎ ◎ ×
T(％) 6.30 6.70 7.20
Note: x represents a color shift phenomenon, and ∈ represents good color expression.
The VA type liquid crystal display devices of comparative example 3a, example 3 and comparative example 3b according to the present invention were manufactured by injecting the Host liquid crystal Host 3 into the VA type liquid crystal cell having cell thicknesses of 2.5 μm, 2.8 μm and 3.5 μm by vacuum injection method, respectively, and the observation of color expression and the test of transmittance were performed on the 3 VA type liquid crystal display devices, and the results are shown in the following table 8:
TABLE 8
Comparative example 3a Example 3 Comparative example 3b
Box thickness d (mum) 2.5 2.8 3.5
Δn a ·d(nm) 293 328 410
Δn b ·d(nm) 265 297 371
Color representation ◎ ◎ ××
T(％) 6.20 6.80 7.20
Note: xx indicates a serious color shift phenomenon, and x indicates excellent color performance.
The VA type liquid crystal display devices of comparative example 4a, example 4 and comparative example 4b according to the present invention were manufactured by injecting the Host liquid crystal Host 4 into the VA type liquid crystal cell having cell thicknesses of 3 μm, 3.5 μm and 4 μm, respectively, by a vacuum injection method, and the observation of color expression and the test of transmittance were performed on the 3 VA type liquid crystal display devices, and the results are shown in the following table 9:
TABLE 9
Comparative example 4a Example 4 Comparative example 4b
Box thickness d (mum) 3 3.5 4
Δn a ·d(nm) 288 336 384
Δn b ·d(nm) 264 308 352
Color representation ◎ ◎ ×
T(％) 6.10 6.90 7.10
Note: x represents a color shift phenomenon, and ∈ represents good color expression.
It can be seen from the data of the above comparative examples and examples that when the relationship between each liquid crystal medium and the cell thickness of the device simultaneously satisfies the conditions (1) to (3) of the present invention, the effect of simultaneously considering both good color expression and appropriate transmittance can be achieved, wherein the performance parameters of Host 1 and Host 4 are substantially consistent, and the expression in the device having the same cell thickness is also substantially consistent, indicating that a good effect can be obtained by matching a specific liquid crystal parameter with a specific device design.
99.7% of Host liquid crystals Host 1, host 2, host 3 and Host 4 were mixed with 0.3% of a polymerizable compound
Figure BDA0002204320340000191
Liquid crystal media containing polymerizable compounds were mixed to form liquid crystal media, and the liquid crystal media were respectively injected into VA type liquid crystal cells having a cell thickness of 3.4 μm by a vacuum injection method, and then uv irradiation was performed using a high pressure mercury lamp in a state where a voltage of 10V was applied to the liquid crystal cells at a frequency of 100Hz, thereby preparing PSVA type liquid crystal display devices of example 5, comparative example 6 and example 6 of the present invention, and the 4 PSVA type liquid crystal display devices were subjected to observation of color expression and measurement of transmittance, with the results as shown in table 10 below:
watch 10
Example 5 Comparative example 5 Comparative example 6 Example 6
Host Host 1 Host 2 Host 3 Host 4
Box thickness d (mum) 3.4 3.4 3.4 3.4
Δn a ·d(nm) 326 374 398 326
Δn b ·d(nm) 299 330 360 299
Color representation ◎ × × ◎
T(％) 7.00 7.10 7.20 7.00
Note: x represents a color shift phenomenon, and ∈ represents good color expression.
As can be seen from the data of the above comparative examples and examples, for the PSVA type liquid crystal display device having the same cell thickness, there are significant differences in color expression and transmittance when liquid crystal media having different liquid crystal parameters are added; however, the results are consistent to show that when the relationship between each liquid crystal medium and the cell thickness of the device satisfies the conditions (1) to (3) of the present invention, the effect of simultaneously achieving both color expression and transmittance can be achieved.
In summary, it can be found that the optical anisotropy values of the liquid crystal medium contained in the liquid crystal display device under different illumination wavelengths are matched with the cell thickness of the liquid crystal display device, so that the prepared liquid crystal display device has proper transmittance and can realize good display effect, and the occurrence rate of the color cast problem is greatly reduced.
The above embodiments are merely illustrative of the technical concept and features of the present invention, and the present invention is not limited thereto, and equivalent changes and modifications made according to the spirit of the present invention should be covered thereby.

Claims (6)

1. A liquid crystal display device, the liquid crystal display device has an upper substrate, a lower substrate and a liquid crystal medium filled between the upper substrate and the lower substrate, the cell thickness d of the liquid crystal display device is 2.5-4.5 μm, characterized in that the liquid crystal medium filled between the upper substrate and the lower substrate simultaneously satisfies the following conditions:
(1)Δn a ·d＜350nm；
(2)Δn b d > 290nm; and
(3)(Δn a -Δn b )·d≤40nm，
wherein the content of the first and second substances,
Δn a the optical anisotropy of the liquid crystal medium at 25 ℃ and under the illumination wavelength of 450nm is shown; and is provided with
Δn b Is the optical anisotropy of the liquid crystal medium at 25 ℃ and 650nm illumination wavelengthSex;
the liquid-crystalline medium contains one or more compounds of the formula M1
Figure FDA0003824415590000011
Wherein, the first and the second end of the pipe are connected with each other,
R M1 and R M2 Each independently represents a linear or branched alkyl group having 1 to 12 carbon atoms,
Figure FDA0003824415590000012
Figure FDA0003824415590000013
1 or non-adjacent 2 or more-CH in the linear or branched alkyl containing 1 to 12 carbon atoms 2 -can be independently replaced by-CH = CH-, -C ≡ C-, -O-, -CO-O-, or-O-CO-; and is
R M1 And/or R M2 Is n-propyl;
the liquid-crystalline medium also comprises one or more compounds of the formula N
Figure FDA0003824415590000014
Wherein the content of the first and second substances,
R N1 and R N2 Each independently represents a linear or branched alkyl group having 1 to 12 carbon atoms,
Figure FDA0003824415590000015
Figure FDA0003824415590000016
1 or non-adjacent 2 or more-CH in the linear or branched alkyl containing 1 to 12 carbon atoms 2 -may be independently replaced by-CH = CH-, -C ≡ C-, -O-, -CO-O-, or-O-CO-, respectively, and are present inOne or more of the groups-H may each be independently substituted with-F or-Cl;
ring (C)
Figure FDA0003824415590000017
And ring
Figure FDA0003824415590000018
Each independently represent
Figure FDA0003824415590000019
Wherein, the first and the second end of the pipe are connected with each other,
Figure FDA00038244155900000110
of one or more-CH 2 -may be replaced by-O-, one or at most two of the ring bonds in the single bond may be replaced by a double bond,
Figure FDA00038244155900000111
may be substituted by-F or-Cl, and one or more rings-CH = may be replaced by-N =;
Z N1 and Z N2 Each independently represents a single bond-CO-O-, -O-CO-, -CH 2 O-、-OCH 2 -、-CH＝CH-、-C≡C-、-CH 2 CH 2 -、-(CH 2 ) 4 -、-CF 2 O-、-OCF 2 -or-CF 2 CF 2 -；
L N1 And L N2 Each independently represents-H or methyl; and is provided with
n N1 Represents 0, 1, 2 or 3,n N2 Represents 0 or 1, and 0. Ltoreq. N N1 +n N2 Less than or equal to 3, when n is N1 When =2 or 3, ring
Figure FDA0003824415590000021
May be the same or different, Z N1 May be the same or different.
2. The liquid crystal display device according to claim 1, wherein the liquid crystal layer is a transparent layerDelta n of the liquid-crystalline medium a And Δ n b Each independently of the other, 0.08 to 0.15.
3. Liquid crystal display device according to claim 1, characterized in that Δ n of the liquid crystal medium a ＞Δn b 。
4. Liquid crystal display device according to claim 1, characterized in that | Δ n of the liquid crystal medium a -Δn b The | is 0.005-0.015.
5. The liquid crystal display device according to claim 1, wherein the liquid crystal medium contains a polymerizable compound.
6. The liquid crystal display device according to claim 5, wherein the polymerizable compound is one or more compounds of the general formula RM
Figure FDA0003824415590000022
Wherein the content of the first and second substances,
X r1 and X r2 Each independently represents-H or methyl;
Sp 1 and Sp 2 Each independently represents a single bond, - (CH) 2 ) a -or- (CH) 2 ) b O-, wherein a and b each independently represent an integer of 1 to 8, and- (CH) 2 ) b The oxygen atom in O-is attached to the aromatic ring;
Z r1 represents a single bond, -CO-O-) -O-CO-, -CH 2 O-、-OCH 2 -、-CH＝CH-、-C≡C-、-CH 2 CH 2 -、-(CH 2 ) 4 -、-CF 2 O-、-OCF 2 -、-CF 2 CF 2 -、-CH＝CH-CO-O-、-CH＝CH-O-CO-、-CO-O-CH＝CH-、-O-CO-CH＝CH-、-CO-O-CH 2 CH 2 -、-O-CO-CH 2 CH 2 -、-CH 2 CH 2 -CO-O-、-CH 2 CH 2 -O-CO-、-CO-O-CH 2 -、-O-CO-CH 2 -、-CH 2 -CO-O-、-CH 2 -O-CO-, -CH = CF-, -CF = CH-, or-CF = CF-;
L r1 and L r2 Each independently represents-F, a linear or branched alkyl or alkoxy group containing 1 to 8 carbon atoms;
ring (C)
Figure FDA0003824415590000023
To represent
Figure FDA0003824415590000024
Wherein
Figure FDA0003824415590000025
May be substituted by-F, straight or branched alkyl or alkoxy containing 1 to 8 carbon atoms;
r1 represents 0 or 1; and is provided with
r2 and r3 each independently represent an integer of 0 to 4.
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