A reflective blue phase liquid crystal display panel and a preparation method thereof

Abstract

The present application relates to the technical field of liquid crystal display, and particularly relates to a reflective blue phase liquid crystal display panel and a preparation method thereof. The reflective blue phase liquid crystal display panel comprises a glass packaging layer, an orientation layer, a blue phase liquid crystal layer, an electrode layer, a substrate layer, an optical absorption layer, and spacers uniformly distributed between the glass packaging layer and the substrate layer, and the orientation layer is provided with a step structure layer; the blue phase liquid crystal layer is filled with a single blue phase liquid crystal material to form, and the crystal face orientation of the blue phase liquid crystal layer is jointly determined by the surface anchoring free energy of the orientation layer and the thickness difference of the step structure layer. The present application is based on the growth of the blue phase liquid crystal induced by the patterned orientation surface, can effectively reduce the surface free energy and reduce the lattice structure defects, and improve the optical properties of the blue phase liquid crystal; meanwhile, by utilizing the difference of the Bragg reflection of different lattices of the same blue phase liquid crystal material, red, green and blue three primary colors can be obtained, and the process steps of preparing three primary colors by using three materials in general blue phase liquid crystal display devices can be simplified.

Description

Technical Field

[0001] This invention relates to the field of liquid crystal display technology, and in particular to a reflective blue phase liquid crystal display panel and its preparation method. Background Technology

[0002] Reflective displays offer advantages such as reflecting ambient light, providing a comfortable reading experience, and saving energy. Compared to traditional electronic paper technology, blue phase liquid crystal is a three-dimensional photonic crystal with a self-assembled double helix structure. Its lattice coefficient is exactly on the order of hundreds of nanometers, and it contains Bragg reflections of the red, green, and blue (RGB) colors in the visible light band. It also features fast electric field response (sub-millisecond level), no need for filters and backlights, and optical isotropy, making it extremely promising for applications in the display field, especially in reflective displays.

[0003] However, blue phase liquid crystal samples typically exhibit a polycrystalline structure, which has inconsistent crystal plane indices and numerous defect structures (i.e., grain boundaries). This affects the optical properties of blue phase liquid crystals, such as Bragg reflectance and reflectance spectral bandwidth. Furthermore, the grain size of fragmented single crystals in blue phase liquid crystals will influence their electro-optic properties, such as hysteresis and driving voltage. The distribution of grain boundaries also reduces the crystal quality of blue phase liquid crystals and increases scattering loss. Therefore, replacing polycrystalline structures with single-crystal blue phase liquid crystals will significantly improve the optical properties (including reflectance and spectral bandwidth) and electro-optic properties (including hysteresis and driving voltage) of blue phase liquid crystals.

[0004] Numerous studies have shown that orientation structure can alter the surface anchoring free energy of blue phase liquid crystals. By combining this with the effect of liquid crystal thickness on the bulk free energy, blue phase liquid crystals with different crystal plane orientations can be obtained, effectively changing the reflective structural color.

[0005] However, in the existing blue phase liquid crystal display panels, the red, green and blue primary colors are provided by three different blue phase liquid crystal materials with different lattice coefficients. Due to the defects in the lattice structure, the pixel boundaries of such display panels are blurred, affecting the clarity and other performance of the display panels.

[0006] In addition, the fabrication of this display panel requires repeating the process of "filling liquid crystal material - heating to form blue phase - polymerization stabilization - cleaning unpolymerized parts" three times. During the fabrication process, the scattering of ultraviolet light in the liquid crystal and the diffusion of the polymer caused by the concentration gradient will lead to lattice structure defects, affecting the performance stability of the display panel. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a reflective blue phase liquid crystal display panel and its preparation method. The aim is to construct a reflective display panel by designing a patterned orientation structure substrate to induce the growth of red, green, and blue primary color pixels from a single blue phase liquid crystal material.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A reflective blue phase liquid crystal display panel includes, from top to bottom: a glass encapsulation layer, an alignment layer, a blue phase liquid crystal layer, an electrode layer, a substrate layer, and an optical absorption layer; and spacers uniformly distributed between the glass encapsulation layer and the substrate layer for controlling the thickness of the blue phase liquid crystal layer, located between the alignment layer and the blue phase liquid crystal layer; a stepped structure layer is provided on the alignment layer; the blue phase liquid crystal layer is formed by filling a single blue phase liquid crystal material, and the crystal orientation of the blue phase liquid crystal layer is determined by the surface anchoring free energy of the alignment layer and the thickness difference of the stepped structure layer.

[0010] Furthermore, the glass encapsulation layer includes: a glass layer, on the surface of which a multilayer antireflective film is deposited by vapor deposition, and an anti-scratch layer is deposited on the antireflective film;

[0011] Furthermore, the glass layer is made of a polymer material or a resin material;

[0012] Furthermore, the orientation layer is divided into three anchoring areas based on the red, green, and blue primary color pixels: the first orientation layer anchoring area is parallel anchoring, the second orientation layer anchoring area is parallel anchoring, and the third orientation layer anchoring area is periodic patterned anchoring composed of parallel anchoring and deparallel anchoring or vertical anchoring and deparallel anchoring; a stepped structure layer is provided on the second orientation layer anchoring area;

[0013] Furthermore, the material of the stepped structure layer is PET film;

[0014] Furthermore, the orientation layer is made of polyimide polymer or photosensitive orientation material;

[0015] Furthermore, the electrode layer consists of a TFT electrode driving structure formed by etching an ITO thin film;

[0016] Furthermore, the substrate layer is made of one of the following materials: glass, silicon wafer, polymer material, or resin material;

[0017] Furthermore, the stacking order of the display panel can also be from top to bottom as follows: glass encapsulation layer, electrode layer, blue phase liquid crystal layer, stepped structure layer, alignment layer, substrate layer, and optical absorption layer.

[0018] The present invention also provides a method for preparing the above-mentioned reflective blue phase liquid crystal display panel, comprising the following steps:

[0019] S1. Prepare an alignment layer on the glass encapsulation layer:

[0020] An anti-reflection film and a scratch-resistant layer are deposited on one side of the glass encapsulation layer, and a parallel anchoring material is coated and oriented on the other side to form an orientation layer. Then, a patterned periodic orientation structure is formed in the anchoring area of ​​the third orientation layer by photolithography to complete the preparation of the orientation layer.

[0021] S2. Preparation of stepped structural layers:

[0022] PET film is selected, and polyimide anchoring areas are coated on the surface. After heating and curing and friction orientation, it is cut into a preset size and then attached to the orientation layer through a bonding process. Laser cutting technology is used to remove the PET film corresponding to the red and blue pixels, leaving only the PET film corresponding to the green pixels, forming a stepped structure layer.

[0023] S3. Fabrication of electrode layer, substrate layer and optical absorption layer:

[0024] A silicon wafer is selected as the substrate layer. The silicon wafer is cut into a size that matches the glass encapsulation layer. An ITO thin film is deposited on the surface of the silicon wafer. The TFT electrode driving structure is formed by etching on the ITO thin film through photolithography to obtain the electrode layer.

[0025] A black organic pigment is uniformly coated on the other side of the silicon wafer, and after baking and curing, an optical absorption layer is formed.

[0026] S4. Assembly and Liquid Crystal Filling:

[0027] The glass encapsulation layer with an alignment layer and a stepped structure layer is bonded to the substrate layer with an electrode layer and an optical absorption layer. Spacers are evenly placed between the two and thermosetting adhesive is used to bond and fix them at the edge of the panel to form a sealed gap. The preset blue phase liquid crystal material is poured into the sealed gap and ensured that the blue phase liquid crystal material fills the entire gap to form a blue phase liquid crystal layer.

[0028] S5. Solidification of blue phase LCD RGB pixels:

[0029] The entire device is heated to the blue phase liquid crystal clearing point, and then cooled at a rate of 0.1℃ / min until a uniform blue phase layer is formed as observed under a microscope. The display panel is then placed under uniform ultraviolet light for curing.

[0030] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0031] By inducing the growth of blue phase liquid crystals based on patterned oriented surfaces, the surface free energy can be effectively reduced. By utilizing the difference in Bragg reflection of different lattice orientations of the same blue phase liquid crystal material, the three primary colors of red, green, and blue can be obtained, reducing lattice structure defects and improving the optical properties of blue phase liquid crystals, such as increasing reflectivity and reducing reflection bandwidth (i.e., increasing brightness and saturation).

[0032] Meanwhile, by utilizing the differences in Bragg reflection of different lattice orientations of the same blue phase liquid crystal material, the three primary colors of red, green, and blue can be obtained, which can simplify the process steps for preparing the three primary colors of general blue phase liquid crystal display devices using three materials. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the overall stacked structure of the reflective blue phase liquid crystal display panel of the present invention;

[0034] Figure 2 This is an exploded view of the overall stacked structure of the reflective blue phase liquid crystal display panel of the present invention;

[0035] Figure 3 This is a schematic diagram of the layered structure of the glass encapsulation layer of the present invention;

[0036] Figure 4 This is a schematic diagram of the partitioned structure of the orientation layer of the present invention;

[0037] Figure 5 This is a schematic diagram of the periodic patterned anchoring structure of the third orientation layer anchoring region of the present invention;

[0038] In the diagram: 1. Glass encapsulation layer; 11. Scratch-resistant layer; 12. Anti-reflective coating; 13. Glass layer; 2. Alignment layer; 21. First alignment layer anchoring area (corresponding to red pixels); 22. Second alignment layer anchoring area (corresponding to green pixels); 23. Third alignment layer anchoring area (corresponding to blue pixels); 3. Step structure layer; 31. Anchoring area; 4. Blue phase liquid crystal layer; 5. Electrode layer; 6. Substrate layer; 7. Optical absorption layer; 8. Spacer. Detailed Implementation

[0039] The technical solutions adopted in this invention will be clearly and completely explained and described below with reference to the accompanying drawings and specific embodiments;

[0040] In the display panel of the present invention, the three primary colors of red, green and blue are all filled with the same material. Different colors are caused by the reflection of different crystal planes. The key to determining the crystal plane orientation is the surface anchoring free energy of the orientation layer 2 and the thickness difference generated by the step structure layer 3.

[0041] First, such as Figure 1-2 As shown, the display panel of the present invention comprises, from top to bottom, a glass encapsulation layer 1, an alignment layer 2, a stepped structure layer 3, a blue phase liquid crystal layer 4, an electrode layer 5, a substrate layer 6, and an optical absorption layer 7, wherein:

[0042] The glass encapsulation layer 1 serves to protect the internal structure and acts as the substrate for the alignment layer 2.

[0043] In this embodiment, as Figure 3As shown, the glass encapsulation layer 1 uses glass layer 13 as a substrate, and glass layer 13 can be used to prepare a flexible display panel using either a polymer material or a resin material.

[0044] A multilayer antireflective film 12 is vapor-deposited on the surface of the glass layer 13 to reduce the reflection of ambient light on the glass surface and improve the visual effect; and an anti-scratch layer 11 is deposited on the top layer of the antireflective film 12 to increase the mechanical strength of the entire display panel.

[0045] Orientation layer 2, which can be prepared using polyimide polymer materials, such as... Figure 4 As shown, the orientation layer 2 is divided into three regions: the first orientation layer anchoring region 21, the second orientation layer anchoring region 22, and the third orientation layer anchoring region 23.

[0046] Furthermore, in this embodiment, the first orientation layer anchoring region 21 is parallel anchored;

[0047] The second orientation layer anchoring zone 22 is parallel anchored;

[0048] The third orientation layer anchoring area 23 is periodically patterned anchored, such as... Figure 5 As shown, periodic patterned anchoring consists of alternating parallel anchoring and retraction parallel anchoring, or vertical anchoring and retraction parallel anchoring.

[0049] The first orientation layer anchoring region 21, the second orientation layer anchoring region 22, and the third orientation layer anchoring region 23 are not limited to the structure given in this embodiment. In other embodiments, they may also be any one or two of parallel anchoring, vertical anchoring, and deparallel anchoring.

[0050] The stepped structure layer 3 can be made of PET film and has a certain thickness. The stepped structure layer 3 is disposed on the second orientation layer anchoring region 22. In this embodiment, the thickness of the stepped structure layer 3 is 15 μm.

[0051] An anchoring area 31 is also provided on the surface of the stepped structure layer 3 away from the second orientation layer anchoring area 22, and the anchoring area 31 is parallel anchoring.

[0052] Blue phase liquid crystal layer 4 is formed by filling a single blue phase liquid crystal material;

[0053] In this embodiment, since the blue phase liquid crystal has Bragg reflection in the red to blue light band, it can selectively reflect natural light, eliminating the need for filters and backlights. The blue phase liquid crystal has a three-dimensional cubic lattice structure, which is macroscopically isotropic, thus eliminating the need for polarizers and effectively reducing the thickness of the display panel.

[0054] Furthermore, located in the blue phase liquid crystal layer 4:

[0055] The red pixel area is only anchored to the first alignment layer region 21, that is, the blue phase liquid crystal is induced to form the blue phase I (110) crystal plane by parallel anchoring, which reflects red light.

[0056] The green pixel area corresponds to the second orientation layer anchoring region 22 and the stepped structure layer 3. That is, the thickness difference between the parallel anchoring and the stepped structure layer 3 is used to induce the blue phase liquid crystal to form the blue phase II (100) crystal plane, which reflects green light.

[0057] The blue pixel area corresponds only to the third orientation layer anchoring region 23, that is, the periodic patterned anchoring induces the blue phase liquid crystal to form the blue phase I (200) crystal plane, which reflects blue light.

[0058] Furthermore, the width of each orientation layer anchoring area can be selected from 20-100μm to meet the display panel's requirements from 4K resolution to standard definition.

[0059] Electrode layer 5 serves as the electrical signal control unit for each pixel. It consists of a TFT electrode driving structure formed by etching an ITO thin film and is used to regulate the voltage of each pixel to regulate the reflectivity.

[0060] Furthermore, the orientation layer 2, the stepped structure layer 3, and the electrode layer 5 correspond one-to-one in spatial dimensions to ensure the structural matching of each pixel.

[0061] Substrate layer 6 serves as the base of the entire display panel and is used to support the various structural layers. Substrate layer 6 can be made of one of glass, silicon wafer, polymer material or resin material. In this embodiment, the thickness of substrate layer 6 is 0.3 mm.

[0062] Furthermore, an ITO thin film can be placed above the substrate layer 6, using the ITO thin film as a conductive material, and then a thin film transistor (TFT) electrode driving structure can be formed on the ITO by photolithography to form the electrode layer 5, and to provide driving support for the electrode layer 5.

[0063] An optical absorption layer 7 is coated below the substrate layer 6. In this embodiment, an optical absorption layer 7 with a thickness of 100 nm is coated below the substrate layer 6.

[0064] The optical absorption layer 7 is used to absorb transmitted light and interference light generated by secondary reflection, effectively enhancing the display contrast of the display panel.

[0065] It also includes: spacers 8 uniformly distributed between the glass encapsulation layer 1 and the substrate layer 6, which are used to control the thickness of the blue phase liquid crystal layer 4. In this embodiment, the spacers 8 are 20 μm in size.

[0066] Secondly, the present invention also provides a method for manufacturing the above-mentioned liquid crystal display, comprising the following:

[0067] S1. An alignment layer 2 is prepared on the glass encapsulation layer 1:

[0068] Specifically, firstly, a multilayer visible light band antireflection film 12 is deposited on the glass encapsulation layer 1, and the process is not limited to vacuum evaporation, electron beam evaporation, magnetron sputtering, etc.; then, an anti-scratch layer 11 is deposited on it, and the process is not limited to chemical vapor deposition, magnetron sputtering, PET lamination, etc.

[0069] Then, a parallel anchoring material is coated on the other side of the glass encapsulation layer 1. The parallel anchoring material can be either a polyimide polymer material or a photosensitive material. The parallel anchoring direction is determined by rubbing orientation or polarized light orientation to form an orientation layer 2. A photolithography material is coated on the orientation layer 2, and a hexagonal symmetrical structure mask is covered on the photoresist surface. Through ultraviolet light exposure, development, and etching, a periodic structure consisting of parallel anchoring and deparallel anchoring is formed in the third orientation layer anchoring region 23, thus completing the preparation of the orientation layer 2.

[0070] The period of the mask pattern for tetragonal and hexagonal symmetric structures is not limited to 230 nm and can be varied according to the lattice coefficient.

[0071] S2. Prepare stepped structural layer 3;

[0072] Specifically, a PET film is selected, a polyimide anchoring area 31 is coated on the surface, and after heating and curing for friction orientation, it is cut into a preset size and attached to the orientation layer 2 through a bonding process. Laser cutting technology is used to remove the PET film corresponding to the red and blue pixels, leaving only the PET film corresponding to the green pixels, forming a stepped structure layer 3 with a thickness of 15μm.

[0073] S3. Fabrication of electrode layer 5, substrate layer 6, and optical absorption layer 7:

[0074] A silicon wafer is selected as the substrate layer 6, and it is cut into a size that matches the glass encapsulation layer 1. An ITO thin film is deposited on the surface of the silicon wafer, and a TFT electrode driving structure is formed on the ITO thin film by photolithography to obtain the electrode layer 5.

[0075] On the other side of the silicon wafer (the side away from the electrode layer 5), black organic pigment is uniformly coated and baked to cure, forming an optical absorption layer 7 with a thickness of 100 nm, thus completing the preparation of the substrate layer 6, the electrode layer 5 and the optical absorption layer 7.

[0076] S4. Assembly and Liquid Crystal Filling:

[0077] The glass encapsulation layer 1 with the alignment layer 2 and the stepped structure layer 3 is bonded to the substrate layer 6 with the electrode layer 5 and the optical absorption layer 7. Spacers 8 with a size of 20μm are evenly placed between the two and are fixed to the edge of the panel with thermosetting adhesive to form a sealed gap. The preset blue phase liquid crystal material is poured into the sealed gap and ensured that the blue phase liquid crystal material fills the entire gap to form a blue phase liquid crystal layer 4.

[0078] S5, curing of blue phase LCD RGB pixels;

[0079] The entire device is heated to the blue phase liquid crystal clearing point, and then cooled at a rate of 0.1℃ / min until a uniform blue phase layer is formed (approximately 1℃) as observed under a microscope. The display panel is then placed under uniform ultraviolet light for curing.

[0080] The structure of the display panel in this application is not limited to the top-to-bottom order, but can also be glass encapsulation layer 1, electrode layer 5, blue phase liquid crystal layer 4, stepped structure layer 3, alignment layer 2, substrate layer 6, and optical absorption layer 7 from top to bottom.

[0081] Finally, the above description is merely an embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, extensions, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A reflective blue phase liquid crystal display panel, comprising: The following layers are arranged sequentially from top to bottom: a glass encapsulation layer (1), an alignment layer (2), a blue phase liquid crystal layer (4), an electrode layer (5), a substrate layer (6), and an optical absorption layer (7), and spacers (8) uniformly distributed between the glass encapsulation layer (1) and the substrate layer (6) for controlling the thickness of the blue phase liquid crystal layer (4), located between the alignment layer (2) and the blue phase liquid crystal layer (4), and a stepped structure layer (3) is provided on the alignment layer (2). The feature is that the blue phase liquid crystal layer (4) is formed by filling a single blue phase liquid crystal material, and the crystal orientation of the blue phase liquid crystal layer (4) is determined by the surface anchoring free energy of the orientation layer (2) and the thickness difference of the stepped structure layer (3).

2. The reflective blue phase liquid crystal display panel according to claim 1, characterized in that, The glass encapsulation layer (1) includes: a glass layer (13), on which a multilayer antireflective film (12) is deposited by vapor deposition, and an anti-scratch layer (11) is deposited on the antireflective film (12).

3. A reflective blue phase liquid crystal display panel according to claim 2, characterized in that, The glass layer (13) is made of polymer or resin.

4. A reflective blue phase liquid crystal display panel according to claim 1, characterized in that, The orientation layer (2) is divided into three anchoring areas based on the red, green and blue primary color pixels: the first orientation layer anchoring area (21) is parallel anchoring, the second orientation layer anchoring area (22) is parallel anchoring, and the third orientation layer anchoring area (23) is periodic patterned anchoring, which consists of parallel anchoring and deparallel anchoring or vertical anchoring and deparallel anchoring. A stepped structure layer (3) is provided on the second orientation layer anchoring area (22).

5. A reflective blue phase liquid crystal display panel according to claim 4, characterized in that, The material of the stepped structure layer (3) is PET film.

6. A reflective blue phase liquid crystal display panel according to claim 4, characterized in that, The orientation layer (2) is made of polyimide polymer or photosensitive orientation material.

7. A reflective blue phase liquid crystal display panel according to claim 1, characterized in that, The electrode layer (5) consists of a TFT electrode driving structure formed by etching an ITO thin film.

8. The reflective blue phase liquid crystal display panel according to claim 1, characterized in that, The substrate layer (6) is made of one of the following materials: glass, silicon wafer, polymer material or resin material.

9. A reflective blue phase liquid crystal display panel according to claim 1, characterized in that, The stacking order of the display panel can also be from top to bottom as follows: glass encapsulation layer (1), electrode layer (5), blue phase liquid crystal layer (4), stepped structure layer (3), alignment layer (2), substrate layer (6), and optical absorption layer (7).

10. A method for manufacturing a reflective blue phase liquid crystal display panel as described in any one of claims 1-9, characterized in that, Includes the following steps: S1. An alignment layer (2) is prepared on the glass encapsulation layer (1): An antireflective film (12) and a scratch-resistant layer (11) are vapor-deposited on one side of the glass encapsulation layer (1), and a parallel anchoring material is coated on the other side and oriented to form an orientation layer (2). Then, a patterned periodic orientation structure is formed in the anchoring area (23) of the third orientation layer by photolithography to complete the preparation of the orientation layer (2). S2. Preparation of stepped structural layer (3): PET film is selected, polyimide anchoring area is coated on the surface, and after heating and curing friction orientation, it is cut into a preset size and attached to the orientation layer (2) through a bonding process. Laser cutting technology is used to remove the PET film corresponding to the red and blue pixels, leaving only the PET film corresponding to the green pixels to form a stepped structure layer (3). S3. Fabrication of electrode layer (5), substrate layer (6) and optical absorption layer (7): A silicon wafer is selected as the substrate layer (6). The silicon wafer is cut into a size that matches the glass encapsulation layer (1). An ITO thin film is deposited on the surface of the silicon wafer. A TFT electrode driving structure is formed on the ITO thin film by photolithography to obtain the electrode layer (5). A black organic pigment is uniformly coated on the other side of the silicon wafer, and after baking and curing, an optical absorption layer is formed (7). S4. Assembly and Liquid Crystal Filling: The glass encapsulation layer (1) with an alignment layer (2) and a stepped structure layer (3) is bonded to the substrate layer (6) with an electrode layer (5) and an optical absorption layer (7). Spacers (8) are evenly placed between the two. Thermosetting adhesive is used to bond and fix the panel edge to form a sealed gap. The preset blue phase liquid crystal material is poured into the sealed gap and the blue phase liquid crystal material is ensured to fill the entire gap to form a blue phase liquid crystal layer (4). S5. Solidification of blue phase LCD RGB pixels: The entire device is heated to the blue phase liquid crystal clearing point, and then cooled at a rate of 0.1℃ / min until a uniform blue phase layer is formed as observed under a microscope. The display panel is then placed under uniform ultraviolet light for curing.

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