CN215813639U

CN215813639U - PNLC display

Info

Publication number: CN215813639U
Application number: CN202122012377.7U
Authority: CN
Inventors: 周炎宏; 余荣; 杨烨; 常碧波
Original assignee: Shantou Goworld Display Plant Ii Co ltd; Shantou Goworld Display Technology Co Ltd
Current assignee: Shantou Goworld Display Plant Ii Co ltd; Shantou Goworld Display Technology Co Ltd
Priority date: 2021-08-25
Filing date: 2021-08-25
Publication date: 2022-02-11
Anticipated expiration: 2031-08-25

Abstract

A PNLC liquid crystal display is provided, the main body of which is a liquid crystal box, the liquid crystal box comprises a first substrate, a second substrate and a liquid crystal layer, the liquid crystal layer is clamped between the first substrate and the second substrate, the inner side surfaces of the first substrate and the second substrate are respectively provided with a first electrode and a second electrode, and the first electrode and the second electrode are provided with an overlapping area forming a display pattern; the liquid crystal layer includes a first liquid crystal part and a second liquid crystal part, the first liquid crystal part is a polymer network formed by polymerization of nematic liquid crystal monomers, and the second liquid crystal part is filled with the polymer network, which is a liquid state nematic liquid crystal doped with dichroic dyes. Such PNLC displays can achieve more display colors.

Description

PNLC display

Technical Field

The utility model relates to a PNLC display, belonging to the technical field of liquid crystal display.

Background

The PNLC display is a Liquid Crystal display using Polymer Network Liquid Crystal (PNLC) as a display medium. The liquid crystal layer of the PNLC display comprises a first liquid crystal part and a second liquid crystal part, wherein the first liquid crystal part is a polymer network formed by polymerization reaction of liquid crystal monomers, and the second liquid crystal part is fluid liquid crystal filled in the polymer network. In a natural state, the first liquid crystal part and the second liquid crystal part have the same optical axis and refractive index to enable the liquid crystal layer to be in a transparent state, and when an electric field is applied, liquid crystal molecules of the second liquid crystal part rotate to enable the optical axis and the refractive index of the liquid crystal molecules to be out of consistency with the first liquid crystal part, so that the liquid crystal layer is in a scattering state with a light scattering effect. Thus, the PNLC display can control the liquid crystal layer at the display pattern to change between a transparent state and a scattering state by applying a voltage to realize display.

In general, the scattering state of PNLC displays is milky white, and the display color of such displays is very monotonous, which limits their applications.

Disclosure of Invention

It is an object of the present invention to provide a PNLC display which can realize more display colors. The design scheme adopted is as follows:

a PNLC display, whose main body is a liquid crystal cell, is characterized in that: the liquid crystal box comprises a first substrate, a second substrate and a liquid crystal layer, wherein the liquid crystal layer is clamped between the first substrate and the second substrate, the inner side surfaces of the first substrate and the second substrate are respectively provided with a first electrode and a second electrode, and the first electrode and the second electrode are provided with an overlapping area forming a display pattern;

the liquid crystal layer includes a first liquid crystal part and a second liquid crystal part, the first liquid crystal part is a polymer network formed by polymerization of nematic liquid crystal monomers, and the second liquid crystal part fills the polymer network and is a fluid nematic liquid crystal doped with dichroic dyes.

The first substrate and the second substrate are generally transparent glass substrates. The first and second substrates are generally bonded to each other by a sealing rubber, which simultaneously seals the liquid crystal layer. A spacer (e.g., spacer balls dispersed in the liquid crystal layer) may be disposed between the first and second substrates to maintain the thickness of the liquid crystal layer. Preferably, the liquid crystal layer is 6 μm-20 μm thick to ensure that it is sufficiently scattering of light in a scattering state at the appropriate drive voltage.

The first and second electrodes are typically transparent conductive films, such as ITO (indium tin oxide) and AZO (zinc aluminum oxide) films, respectively coated on the inner surfaces (surfaces close to the liquid crystal layer) of the first and second substrates and patterned (e.g., photo-etched). Generally, the first and second electrodes are overlapped to form an overlapping region corresponding to the display pattern. The first and second electrodes are generally connected to a driving circuit (e.g., a passive driving circuit) of the liquid crystal display to apply a driving voltage to form a driving electric field in the liquid crystal layer of the display pattern.

The first and second liquid crystal portions are typically birefringent nematic liquid crystals or compounds or mixtures thereof, and thus have optical axes determined by their molecular orientation (i.e. the direction of the molecular long axis or the average direction), and typically have a first refractive index n in a direction parallel to and perpendicular to the optical axes, respectively₁And a second refractive index n₂(generally there is n)₁>n₂) In order to maintain transparency in a natural state, the first and second liquid crystal sections are easily made to have n coincident with each other by selecting a liquid crystal material₁And n₂I.e. having a uniform birefringence.

In the manufacture of the liquid crystal cell, a nematic liquid crystal monomer, for example, a molecule end modified with a non-saturated group (e.g., -CH = CH)₂) The nematic liquid crystal, photosensitizer and the second liquid crystal part are fully mixed, the liquid crystal layer is formed between the first substrate and the second substrate by the common methods of liquid crystal display such as pouring, drip irrigation and the like, and then ultraviolet light is irradiated to enable the monomer of the first liquid crystal part to generate cross-linking reactionAnd is cured into a polymer network in which the second liquid crystal part is filled in a fluid state. Before curing, the liquid crystal layer generally has a certain orientation (e.g., horizontal orientation or vertical orientation) under the action of the inner surfaces of the first and second substrates, and when the first liquid crystal portion undergoes polymerization curing, its orientation is fixed (and subsequently unaffected by the electric field), while the second liquid crystal portion, under the action of the inner surfaces of the substrates and the first liquid crystal portion, also maintains a uniform orientation in a natural state.

Preferably, the volume ratio of the first liquid crystal part to the second liquid crystal part is 0.02-0.1, so that the main component of the liquid crystal layer is the second liquid crystal part, when the first liquid crystal part and the second liquid crystal part have the volume ratio, the first liquid crystal part can be ensured to be a polymer network containing a large number of communicated holes after being cured, and the second liquid crystal part has a large volume ratio, so that the liquid crystal layer has very sensitive response to an electric field, and the driving voltage required by the liquid crystal layer is also lower. The first and second liquid crystal portions are mixed well (mixing may be performed by ultrasonic emulsification or the like) to improve the scattering property of the liquid crystal layer when an electric field is applied to the liquid crystal layer, and the polymer network preferably has a pore size of 0.2 to 2 μm.

The dichroic dye may be an anthracene rolling or azo-based dye molecule doped in the second liquid crystal portion, having a rod-like molecular structure resembling a liquid crystal, and exhibiting different absorptance when light passes through the dichroic dye in a polarization direction at different angles to the axes of the dye molecules, and being absorbed when light of certain wavelengths exists in a polarization state parallel to the axes of the dye molecules. In general, when a dichroic dye is mixed in the second liquid crystal portion, the molecular axis direction thereof coincides with the liquid crystal orientation, and when the liquid crystal molecules are rotated by an electric field, the dye molecules follow the rotation thereof, thereby changing the absorption of light. In general, the dichroic dye may be one, such as blue or violet, or a mixture of two or more, such as blue, red, etc., dichroic dyes. Preferably, the dichroic dye has a mass percentage concentration of 1-5% in the second liquid crystal portion, whereby its coloring effect is ensured.

In order to determine the orientation of the liquid crystal layer, it is preferable that the inner side surfaces of the first and second substrates are provided with a horizontal alignment layer directly in contact with the liquid crystal layer, and the second liquid crystal portion is composed of positive nematic liquid crystal (liquid crystal molecules tend to be parallel to an electric field in the electric field).

In order to determine the orientation of the liquid crystal layer, it is also preferable that the inner sides of the first and second substrates are provided with a vertical alignment layer directly contacting the liquid crystal layer, and the second liquid crystal part is composed of negative nematic liquid crystal (in an electric field, liquid crystal molecules tend to be perpendicular to the electric field), whereby, in a natural state, the second liquid crystal part and its dichroic dye molecules are perpendicular to the substrate plane, which absorbs less light, resulting in higher transparency.

In a natural state, the first and second liquid crystal portions have the same orientation and refractive index and thus are transparent, and the dye molecules are also unidirectionally aligned with the second liquid crystal portion, and thus can absorb only a part of the polarized light at most, thereby exhibiting a greater transparency as a whole. In the scattering state, the light is reflected in the liquid crystal layer for multiple times, the polarization state of the light is changed in the reflection process and is absorbed by the dichroic dye molecules for multiple times, and finally the liquid crystal layer is in a turbid state with colors (determined by the absorption wavelengths of the dye molecules), and different scattering state colors can be obtained by changing the types of the dichroic dye. Therefore, compared with the prior art, the PNLC display can realize the display of display colors, and has wider application range.

The technical solution of the present invention is further explained by the accompanying drawings and examples.

Drawings

Fig. 1 is a schematic diagram of a liquid crystal cell of a PNLC display according to a first embodiment;

FIG. 2 is a schematic cross-sectional view of a liquid crystal cell of a PNLC display according to a first embodiment;

FIG. 3 is a schematic diagram of the polymer network of the liquid crystal layer of the PNLC display according to the first embodiment;

FIG. 4 is a schematic diagram of a PNLC display according to the first embodiment, in which the liquid crystal layer is in a natural state;

FIG. 5 is a schematic diagram of a PNLC display according to the first embodiment, in which the liquid crystal layer is under the condition of applying an electric field;

FIG. 6 is a schematic diagram of a PNLC display of the second embodiment in which the liquid crystal layer is in a natural state;

fig. 7 is a schematic view of a PNLC display according to the second embodiment, in which a liquid crystal layer is under an electric field applied state.

Detailed Description

Example one

As shown in fig. 1, the main body of the PNLC liquid crystal display is a liquid crystal cell 100, the liquid crystal cell 100 includes a first substrate 10, a second substrate 20 and a liquid crystal layer 30, the first and

second substrates

10 and 20 are transparent glass substrates, and are bonded to each other by a sealing rubber ring 40, and the sealing rubber ring 40 simultaneously forms a seal for the liquid crystal layer 30. Spacer balls (not shown) are provided between the first and

second substrates

10 and 20 to maintain the thickness (e.g., 6 μm) of the liquid crystal layer 30.

As shown in fig. 2, the liquid crystal layer 30 is sandwiched between the first and

second substrates

10, 20, the inner side of the first substrate 10 is provided with a first electrode 11 and a first alignment layer 12, the inner side of the second substrate 20 is provided with a second electrode 21 and a second alignment layer 22, the first and

second electrodes

11, 12 are ITO films plated on the inner surfaces of the first and

second substrates

10, 20 respectively and patterned by photolithography, and have an overlapping region constituting a display pattern, and the first and

second electrodes

11, 12 can apply a driving voltage to form a driving electric field in the liquid crystal layer 30 at the display pattern when connected with a liquid crystal display driving circuit.

As shown in fig. 2 to 5, the liquid crystal layer 30 includes a first liquid crystal portion 31 and a second liquid crystal portion 32, the first liquid crystal portion 31 is a polymer network formed by polymerizing liquid crystal monomers, and the second liquid crystal portion 32 fills the polymer network 31, which is a liquid nematic liquid crystal containing a dichroic dye 33. In the fabrication of liquid crystal cell 100, the ends of the molecules are first modified with unsaturated groups (e.g., -CH = CH)₂) The nematic liquid crystal monomer(s) and the photosensitizer(s), and the positive nematic liquid crystal (i.e., the second liquid crystal part) containing the dichroic dye(s) are sufficiently mixed (the volume ratio of the first liquid crystal part 31 to the second liquid crystal part 32 is 0.02 to 0.1, which is formulated to have uniform birefringence, and the dichroic dye 33 is typically pre-mixed in the second liquid crystal part 32 at a mass percentage concentration of 1-5%), and the liquid crystal is developed by pouring, dripping, or the likeThe display is usually disposed between the first and

second substrates

10, 20 to form a liquid crystal layer 30, and then irradiated with ultraviolet light to cause the monomer of the first liquid crystal portion 31 to undergo a cross-linking reaction and be cured into a polymer network, and the second liquid crystal portion 32 is filled in the polymer network 31 in a fluid state.

The first and

second alignment layers

12, 22 are both horizontal alignment layers (a horizontal alignment polyimide coating commonly used in liquid crystal displays) that are also typically subjected to an axially uniform orientation rubbing process. Before curing, the liquid crystal layer 30 is in contact with the first and

second alignment layers

12 and 22 to have a certain horizontal orientation, and when the first liquid crystal portion 31 is polymerized and cured, its orientation is fixed (and subsequently unaffected by the electric field), while the second liquid crystal portion 32 and its dichroic dye 33 molecules are acted on by the inner surface of the substrate and the first liquid crystal portion 31 to maintain a uniform orientation in a natural state.

The dichroic dye 33 may be one kind, such as a blue, red or violet dichroic dye 33, or may be a mixture of two or more kinds, such as a blue, red, etc. dichroic dye 33.

As shown in fig. 4, in a natural state, the first and second

liquid crystal portions

31 and 32 have the same orientation and refractive index and thus are in a transparent state, and at this time, the dye molecules are also aligned in a horizontal direction following the orientation of the second liquid crystal portion 32, which can absorb only a part of the polarized light L at most, and the liquid crystal layer 30 as a whole exhibits high transparency. As shown in fig. 5, when an electric field is applied to the liquid crystal layer 30 at the display pattern through the first and

second electrodes

11 and 12, the liquid crystal molecules inside the second liquid crystal portion 32 drive the dye molecules to rotate, the birefringence consistency between the dye molecules and the first liquid crystal portion 31 is broken, the liquid crystal layer 30 has a scattering effect on the light L, and a scattering state occurs, the light L can be reflected multiple times in the liquid crystal layer 30, the polarization state of the light L changes during reflection, and is absorbed by the dichroic dye 33 molecules multiple times, so that the liquid crystal layer 30 finally assumes a cloudy state with colors (determined by the absorption wavelengths of the dye molecules).

Example two

As shown in fig. 6 and 7, based on the first embodiment, the first and second alignment layers are changed to vertical alignment layers (such as a vertical alignment polyimide coating commonly used in liquid crystal displays), and the liquid crystal of the second liquid crystal portion 32 is changed to negative nematic liquid crystal (in an electric field, liquid crystal molecules tend to be perpendicular to the electric field), so that, in a natural state, the second liquid crystal portion 32 and the dichroic dye 33 molecules thereof are perpendicular to the substrate surface, and the absorption of light L is less, so that the transparency is higher, thereby forming the second embodiment of the present invention.

In addition, it should be noted that the names of the parts and the like of the embodiments described in the present specification may be different, and the equivalent or simple change of the structure, the characteristics and the principle described in the present patent idea is included in the protection scope of the present patent. Various modifications, additions and substitutions for the specific embodiments described may be made by those skilled in the art without departing from the scope of the utility model as defined in the accompanying claims.

Claims

1. A PNLC display, the main body of which is a liquid crystal cell, characterized in that:

the liquid crystal box comprises a first substrate, a second substrate and a liquid crystal layer, wherein the liquid crystal layer is clamped between the first substrate and the second substrate, the inner side surfaces of the first substrate and the second substrate are respectively provided with a first electrode and a second electrode, and the first electrode and the second electrode are provided with an overlapping area forming a display pattern;

2. The PNLC display of claim 1, wherein: the thickness of the liquid crystal layer is 6 μm-20 μm.

3. The PNLC display of claim 1, wherein: the first liquid crystal section and the second liquid crystal section have uniform birefringence.

4. The PNLC display of claim 1, wherein: the volume ratio of the first liquid crystal part to the second liquid crystal part is 0.02-0.1.

5. The PNLC display of claim 1, wherein: the dichromatic dye is a dye molecule of an anthracene rolling system or an azo system.

6. The PNLC display of claim 1, wherein: the dichroic dye is a blue or violet dichroic dye.

7. The PNLC display of claim 1, wherein: the dichroic dye is a mixture of two or more dichroic dyes.

8. The PNLC display of claim 1, wherein: the mass percentage concentration of the dichroic dye in the second liquid crystal portion is 1-5%.

9. The PNLC display of claim 1, wherein: the inner side surfaces of the first substrate and the second substrate are provided with horizontal alignment layers which are in contact with the liquid crystal layer, and the second liquid crystal part is formed by positive nematic liquid crystal.

10. The PNLC display of claim 1, wherein: and vertical alignment layers contacting the liquid crystal layer are arranged on the inner side surfaces of the first substrate and the second substrate, and the second liquid crystal part is composed of negative nematic liquid crystal.