CN113789182B

CN113789182B - PSVA display device and vehicle-mounted application thereof

Info

Publication number: CN113789182B
Application number: CN202111074073.1A
Authority: CN
Inventors: 毛林峰; 蒋建青; 钟宇铖; 孙武峰; 赵龙旦; 陈瑛; 单元龙
Original assignee: Zhejiang Automobile Instrument Co ltd
Current assignee: Zhejiang Automobile Instrument Co ltd
Priority date: 2021-09-14
Filing date: 2021-09-14
Publication date: 2023-02-21
Anticipated expiration: 2041-09-14
Also published as: CN113789182A

Abstract

Disclosed is a PSVA display device comprising upper and lower substrates having polyimide PI alignment layers on inner surfaces thereof and a liquid crystal cell sandwiched between the upper and lower substrates, the liquid crystal cell filled with a VA mode display medium composed of a polymerizable mixture and a liquid crystal mixture containing a first component and a second component. The application of the display device in an on-board display such as an all-liquid crystal instrument panel is also disclosed. The display device not only has faster response speed, but also can provide better induced pretilt angle change value.

Description

PSVA display device and vehicle-mounted application thereof

Technical Field

The invention belongs to the field of liquid crystal display, and particularly relates to a PSVA display device and vehicle-mounted application thereof.

Background

With the rapid development of economy and the improvement of the living standard of people, automobiles become main vehicles of ordinary families. As a device for reflecting the operation status of each system of an automobile, an automobile dashboard is one of the most contacted automobile parts in daily life. Traditionally, the rotation speed, water temperature, oil quantity and speed per hour are displayed by a mechanical instrument panel. The mechanical instrument panel has the characteristics of stable technology, maturity and reliability.

However, in recent years, due to the rapid development of automobile, communication and display technologies, more intuitive and more modern display devices are required to meet the demand of people for instant messaging, navigation and entertainment, and thus, full liquid crystal dashboards are called for. The novel instrument panel is applied to the automobile by the characteristics of unique lightness, low power consumption and colored flowers to replace the traditional mechanical instrument panel, realizes the digital display function and is used for displaying the average oil consumption, the instantaneous oil consumption, the outdoor temperature, the average speed, the driving time, the driving mileage, the navigation and the multimedia entertainment of the automobile. The full liquid crystal instrument panel is safer during driving; the display effect is better, and the science and technology sense is stronger.

As a liquid crystal display device for an automobile instrument panel, display modes such as TN (twisted nematic), STN (super twisted nematic), and VA (vertical alignment) are commonly used.

The response time of TN and STN display modes is short, the working temperature is wide, but the contrast and the visual angle are not ideal.

The VA display mode has a wide viewing angle and a high contrast ratio, and also has a high response speed. This requires that the negative liquid crystal medium filled in the liquid crystal cell has a large absolute value, a low dynamic viscosity, and a high nematic phase-isotropic liquid phase transition temperature, and that the refractive index anisotropy of the liquid crystal medium be adjusted to within an appropriate range according to the setting of the product of the refractive index anisotropy and the thickness of the liquid crystal cell.

Japanese laid-open patent publication JP2006-233182A discloses a compound having a large absolute value of a negative liquid crystal medium and a liquid crystal medium comprising the same, but the kinetic viscosity of the liquid crystal medium is still unsatisfactory.

Japanese laid-open patent publication JP2006-37054A discloses that the addition of a liquid crystal monomer having an alkenyl group to a negative liquid crystal medium can improve the kinetic viscosity and response speed.

Japanese laid-open patent publication JP2006-301643A discloses that the response speed of a VA display mode liquid crystal cell is improved using a liquid crystal medium of large specific parameters. The specific parameter is a measure of the response speed, and gamma 1/K ₃₃ Inversely proportional and proportional to the square of Δ n. However, the above liquid crystal media also fail to achieve the effect of reducing the rotational viscosity γ 1 as much as possible while increasing K while maintaining the refractive index anisotropy and the nematic phase-isotropic liquid phase transition temperature at a moderate temperature ₃₃ Numerical values.

In addition, as an upgrade mode of the VA display mode, a Polymer Stabilized Vertical Alignment (PSVA) display mode can further shorten the response time of the liquid crystal cell and increase the light transmittance. In the PSVA mode display device, a liquid crystal medium containing a polymerizable monomer compound and a liquid crystal monomer is injected between substrates, the liquid crystal monomer is aligned under the action of an electric field, the polymerizable monomer compound is polymerized at the same time, the polymerizable monomer compound and the polymerizable monomer compound are subjected to phase separation, a polymer obtained by polymerization forms regular protrusions on an alignment film, the liquid crystal monomer is aligned, and a certain pretilt angle is generated.

European patent publication EP1378557A1 discloses a liquid crystal medium comprising (a) a cyclohexylene-or phenylene-difluorophenylene compound of the formula (I); (b) A cyclohexylene-cyclohexylene (or phenylene) -difluorophenylene compound of the formula (II); (c) a polymerizable compound. The response time, especially the graytone response time, is significantly reduced compared to mixtures without the addition of the polymerizable compound. However, the patent discloses that the induced pretilt angle change value after UV irradiation is still unsatisfactory.

Therefore, it is desirable to provide a PSVA display device and its vehicle-mounted application with faster response speed and a certain pretilt angle.

Disclosure of Invention

The invention aims to provide a PSVA display device with higher response speed and a certain pretilt angle and vehicle-mounted application thereof. Compared with the prior art, the PSVA display device not only has faster response speed, but also can provide better induced pretilt angle change value.

In order to solve the technical problem, the invention adopts the following technical scheme: a PSVA display device comprising upper and lower substrates having polyimide PI alignment layers on their inner surfaces and a liquid crystal cell sandwiched between the upper and lower substrates, the liquid crystal cell being filled with a VA mode display medium consisting of a polymerizable mixture and a liquid crystal mixture comprising a first component and a second component, characterized in that the first component comprises a compound of formula I and a compound of formula II,

formula I;

formula II;

the second component includes a compound having negative dielectric anisotropy and an absolute value greater than 3.

The PSVA display device provided by the invention has the advantages that the content of the compound shown in the formula I is 4-12%, and preferably 6-8%; the content of the compound of the formula II is 10-30%, preferably 15-25%; based on the total weight of the liquid crystal mixture.

The PSVA display device according to the present invention, wherein the second component comprises both the compound of formula III and the compound of formula IV,

formula III;

wherein R is ₁ Represents an alkenyl group of 2 to 8 carbon atoms, preferably 2 to 6 carbon atoms; r ₂ Represents an alkyl or alkoxy group of 1 to 8 carbon atoms, preferably 1 to 6 carbon atoms;

formula IV;

wherein R is ₃ -R ₄ Each independently represents an alkyl or alkoxy group of 1 to 8 carbon atoms, preferably 1 to 6 carbon atoms.

In the present invention, alkenyl is defined as one or more non-adjacent CH ₂ Alkyl substituted with CH = CH.

The PSVA display device provided by the invention has the advantages that the content of the compound shown in the formula III is 12-20%, preferably 14-18%; the content of the compound of the formula IV is 10-20%, preferably 12-18%; based on the total weight of the liquid crystal mixture.

The PSVA display device according to the present invention, wherein the second component further comprises a compound of formula V,

formula V;

wherein R is ₅ -R ₆ Each independently represents an alkyl or alkoxy group of 1 to 8 carbon atoms, preferably 1 to 6 carbon atoms.

The PSVA display device provided by the invention has the advantages that the content of the compound shown in the formula V is 5-9%, preferably 6-8%; based on the total weight of the liquid crystal mixture.

The PSVA display device according to the present invention, wherein the second component further comprises a compound of formula VI and/or a compound of formula VII,

formula VI;

formula VII;

wherein R is ₇ Or R ₉ Represents an alkyl group of 1 to 8 carbon atoms, preferably 1 to 6 carbon atoms; r ₈ Or R ₁₀ Represents an alkyl or alkoxy group of 1 to 8 carbon atoms, preferably 1 to 6 carbon atoms; ring A represents

Or

The PSVA display device provided by the invention has the advantages that the content of the compound of the formula VI and/or the compound of the formula VII is 6-12%, and is preferably 8-10%; based on the total weight of the liquid crystal mixture.

The PSVA display device according to the present invention, wherein the first component further comprises a compound of formula VIII,

formula VIII.

The PSVA display device provided by the invention has the advantages that the content of the compound shown in the formula VIII is 4-12%, preferably 6-10%; based on the total weight of the liquid crystal mixture.

The PSVA display device according to the present invention, wherein the first component further comprises a compound of formula IX,

formula IX;

wherein R is ₁₁ -R ₁₂ Represents an alkyl group of 1 to 8 carbon atoms, preferably 1 to 6 carbon atoms.

The PSVA display device according to the invention, wherein the compound of formula IX is present in an amount of 3-7%, preferably 4-6%; based on the total weight of the liquid crystal mixture.

The PSVA display device according to the present invention, wherein the first component further comprises a compound of formula X,

formula X.

The PSVA display device provided by the invention is characterized in that the content of the compound shown in the formula X is 6-12%, preferably 8-10%; based on the total weight of the liquid crystal mixture.

The PSVA display device provided by the invention has the advantages that the content of the first component is 40-60%, preferably 48-56%; the content of the second component is 40-60%, preferably 44-50%; based on the total weight of the liquid crystal mixture.

In a preferred embodiment, the liquid-crystal mixture according to the invention does not comprise 3-CC-V.

In a further preferred embodiment, the liquid-crystal mixture according to the invention consists exclusively of the first component and the second component.

In a further preferred embodiment, the liquid-crystal mixtures according to the invention advantageously consist of compounds of the formulae I to X described above.

The PSVA display device provided by the invention, wherein the addition amount of the polymerizable mixture is 0.1-0.5wt% based on the total weight of the liquid crystal mixture.

Preferably, the polymerizable mixture is added in an amount of 0.2 to 0.4wt% based on the total weight of the liquid crystal mixture.

The PSVA display device according to the present invention, wherein the polymerizable mixture comprises a polymerizable monomer compound and a photoinitiator.

The PSVA display device according to the present invention, wherein the polymerizable monomer compound is selected from the group consisting of,

advantageously, the proportion by weight of the polymerizable monomer compounds in the polymerizable mixture is from 90 to 99.5% by weight.

Preferably, the weight proportion of the polymerizable monomer compound in the polymerizable mixture is 95 to 99wt%.

In another aspect, the invention further provides the application of the PSVA display device according to the invention in a vehicle-mounted display, wherein the vehicle-mounted display is selected from a full liquid crystal instrument panel.

The inventors have found that combining different monomeric compounds using specific proportions and specific structures, in particular specific cyclic units and side groups, results in a liquid crystal mixture which is further mixed with a polymerizable mixture and fills the liquid crystal cells of an automotive all liquid crystal instrument panel. Based on the PSVA display device, the response speed is higher, and meanwhile, a certain pretilt angle is provided. Compared with the prior art, the PSVA display device not only has faster response speed, but also can provide better induced pretilt angle change value.

Detailed Description

The present invention will be further described with reference to the following embodiments.

It should be understood that the detailed description of the invention is merely illustrative of the spirit and principles of the invention and is not intended to limit the scope of the invention. Furthermore, it should be understood that various changes, substitutions, deletions, modifications or adjustments may be made by those skilled in the art after reading the teachings of the present invention, and such equivalents are also within the scope of the invention as defined in the appended claims.

In the present invention, all parts are parts by weight unless otherwise specified; all percentages are by weight; cp denotes clearing point in deg.C.

Δ n represents the optical anisotropy value at 25 ℃ and 589 nm.

Δ ε represents the value of the dielectric anisotropy obtained with a 6 μm thick VA test cell at 25 ℃ and 1 kHz.

γ 1 represents the rotational viscosity (mPas) measured at 25 ℃.

K ₃₃ Denotes the elastic constant K measured at 25 DEG C ₃₃ (pN)。

In the present invention, each monomer compound is represented by a three-stage abbreviation of (cyclic unit + linker) + left side group + right side group. Wherein,

linker and pendant group:

n(O)-＝C _n H _2n+1 (O)-；

-(O)n＝-(O)C _n H _2n+1 ；

Vn-＝CH ₂ ＝CHC _n H _2n -；

-nV＝-C _n H _2n CH＝CH ₂ ；

nV-＝C _n H _2n CH＝CH-；

-V＝-CH＝CH ₂ ；

-T-＝-C≡C-；

-1O-＝-CH ₂ O-

n＝C _n H _2n+1 ；

n = a natural number;

o represents an oxygen atom.

Cyclic unit:

example 1

Liquid crystal mixture LC1

Δn＝0.107；Δε＝-3.8；Cp＝77.4；γ1＝97；K ₃₃ ＝16.4；γ1/K ₃₃ ＝5.9。

98wt% of polymerizable monomer compound and 2wt% of UV photoinitiator Irgacure651 were co-dissolved to obtain a polymerizable mixture. Then, the polymerizable mixture was added to the liquid crystal mixture LC1 in a proportion of 0.3% by weight of the liquid crystal mixture and sufficiently dissolved in the liquid crystal mixture to obtain a PLC-1 display medium.

The polymerizable monomer compound has the following structural formula:

example 2

Liquid crystal mixture LC2

Δn＝0.103；Δε＝-3.6；Cp＝75.9；γ1＝92；K ₃₃ ＝15.1；γ1/K ₃₃ ＝6.1。

98wt% of polymerizable monomer compound and 2wt% of UV photoinitiator Irgacure651 were co-dissolved to obtain a polymerizable mixture. Then, the polymerizable mixture was added to the liquid crystal mixture LC2 in an amount of 0.3% by weight of the liquid crystal mixture and sufficiently dissolved in the liquid crystal mixture to obtain a PLC-2 display medium.

The polymerizable monomer compound has the following structural formula:

comparative example 1

Liquid crystal mixture C-LC1

Δn＝0.104；Δε＝-3.6；Cp＝76.1；γ1＝107；K ₃₃ ＝13.2；γ1/K ₃₃ ＝8.1。

98wt% of a polymerizable monomer compound and 2wt% of a UV photoinitiator Irgacure651 were co-melted to obtain a polymerizable mixture. Then, the polymerizable mixture was added to the liquid crystal mixture C-LC1 in an amount of 0.3% by weight of the liquid crystal mixture and sufficiently dissolved in the liquid crystal mixture to obtain a C-PLC-1 display medium.

The polymerizable monomer compound has the following structural formula:

the PLC-1 display medium of example 1, the PLC-2 display medium of example 2, and the C-PLC-1 display medium of comparative example 1 were filled in a VA test cell having a thickness of 6 μm (polyimide PI alignment layer on the inner surfaces of upper and lower substrates) for an all liquid crystal instrument panel of an automobile using a square wave voltage of 6V (frequency 1 kHz) and 100MW/cm ² The UV light irradiation was stopped for 2min before 320nm, and the initial pretilt angle before UV light irradiation and the pretilt angle after polymerization after irradiation were measured, while the response time (. Tau.ms) was measured. The latter is defined as the rise time and fall time of the VA test cell at a drive voltage of 6VSum of (1) and (b); the former is defined as the time for the transmittance to rise from 10% of the maximum transmittance until 90% is reached; the latter is the time for the transmittance to drop from 90% of the maximum transmittance until 10% is reached.

See table 1 for results.

TABLE 1

As can be seen from table 1, the PSVA display devices of examples 1-2 of the present invention not only have faster response speed, but also provide better induced pretilt angle variation values than comparative example 1.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.

Claims

1. A PSVA display device comprising an upper substrate and a lower substrate and a liquid crystal cell sandwiched between the upper and lower substrates, the upper and lower substrates having polyimide PI alignment layers on inner surfaces thereof, the liquid crystal cell being filled with a VA mode display medium, the display medium consisting of a polymerizable mixture and a liquid crystal mixture, the liquid crystal mixture consisting of a first component and a second component, characterized in that the first component consists of a compound of formula I, a compound of formula II, a compound of formula VIII, a compound of formula IX, and a compound of formula X,

formula I;

formula II;

formula VIII;

formula IX;

wherein R is ₁₁ -R ₁₂ Represents an alkyl group of 1 to 8 carbon atoms;

a formula X;

the content of the compound of the formula I is 4-12%;

the content of the compound of the formula II is 10-30%;

the content of the compound of the formula VIII is 4-12%;

the content of the compound of the formula IX is 3-7%;

the content of the compound of the formula X is 6-12%;

all based on the total weight of the liquid crystal mixture;

the second component comprises a compound having a negative dielectric anisotropy and an absolute value of greater than 3 and consists of a compound of formula III, a compound of formula IV, a compound of formula V, and a compound of formula VI and/or a compound of formula VII,

formula III;

wherein R is ₁ Represents an alkenyl group of 2 to 8 carbon atoms; r ₂ Represents an alkyl or alkoxy group of 1 to 8 carbon atoms;

formula IV;

wherein R is ₃ -R ₄ Each independently represents an alkyl or alkoxy group of 1 to 8 carbon atoms;

formula V;

wherein R is ₅ -R ₆ Each independently represents an alkyl or alkoxy group of 1 to 8 carbon atoms;

formula VI;

formula VII;

wherein R is ₇ Or R ₉ Represents an alkyl group of 1 to 8 carbon atoms; r ₈ Or R ₁₀ Represents an alkyl or alkoxy group of 1 to 8 carbon atoms; ring A represents

Or

；

The content of the compound of the formula III is 12-20%;

the content of the compound of the formula IV is 10-20%;

the content of the compound of the formula V is 5-9%;

the content of the compound of formula VI and/or the compound of formula VII is 6-12%;

all based on the total weight of the liquid crystal mixture;

the polymerizable mixture comprises a polymerizable monomer compound and a photoinitiator; the polymerizable monomer compound is selected from the group consisting of,

。

2. a PSVA display device according to claim 1, wherein R ₁₁ -R ₁₂ Represents an alkyl group of 1 to 6 carbon atoms.

3. A PSVA display device according to claim 1 or 2, wherein the compound of formula I is present in an amount of 6-8%; based on the total weight of the liquid crystal mixture.

4. A PSVA display device according to claim 1 or 2, wherein the compound of formula II is present in an amount of 15-25%; based on the total weight of the liquid crystal mixture.

5. A PSVA display device according to claim 1 or 2, wherein the compound of formula VIII is present in an amount of 6-10%; based on the total weight of the liquid crystal mixture.

6. A PSVA display device according to claim 1 or 2, wherein the compound of formula IX is present in an amount of 4-6%; based on the total weight of the liquid crystal mixture.

7. A PSVA display device according to claim 1 or 2, wherein the compound of formula X is present in an amount of 8-10%; based on the total weight of the liquid crystal mixture.

8. A PSVA display device according to claim 1 or 2, wherein R ₁ Represents an alkenyl group of 2 to 6 carbon atoms; r ₂ Represents an alkyl or alkoxy group of 1 to 6 carbon atoms.

9. A PSVA display device according to claim 1 or 2, wherein R ₃ -R ₄ Each independently represents an alkyl or alkoxy group of 1 to 6 carbon atoms.

10. A PSVA display device according to claim 1 or 2, wherein R ₅ -R ₆ Each independently represents an alkyl or alkoxy group of 1 to 6 carbon atoms.

11. A PSVA display device according to claim 1 or 2, wherein R ₇ Or R ₉ Represents an alkyl group of 1 to 6 carbon atoms; r ₈ Or R ₁₀ Represents an alkyl or alkoxy group having 1 to 6 carbon atoms.

12. A PSVA display device according to claim 1 or 2, wherein the compound of formula III is present in an amount of 14-18%; based on the total weight of the liquid crystal mixture.

13. A PSVA display device according to claim 1 or 2, wherein the compound of formula IV is present in an amount of 12-18%; based on the total weight of the liquid crystal mixture.

14. A PSVA display device according to claim 1 or 2, wherein the compound of formula V is present in an amount of 6-8%; based on the total weight of the liquid crystal mixture.

15. A PSVA display device according to claim 1 or 2, wherein the compound of formula VI and/or the compound of formula VII is present in an amount of 8-10%; based on the total weight of the liquid crystal mixture.

16. A PSVA display device according to claim 1 or 2, wherein the first component content is 40-60%; the content of the second component is 40-60%; based on the total weight of the liquid crystal mixture.

17. A PSVA display device according to claim 1 or 2, wherein the first component content is 48-56%; based on the total weight of the liquid crystal mixture.

18. A PSVA display device according to claim 1 or 2, wherein the second component content is 44-50%; based on the total weight of the liquid crystal mixture.

19. A PSVA display device according to claim 1 or 2, wherein the polymerizable mixture is added in an amount of 0.1-0.5wt% based on the total weight of the liquid crystal mixture.

20. A PSVA display device according to claim 1 or 2, wherein the weight proportion of the polymerizable monomer compound in the polymerizable mixture is 90-99.5wt%.

21. Use of a PSVA display device according to any of claims 1-20 in an in-vehicle display selected from an all liquid crystal dashboard.