CN111308791B

CN111308791B - Photo-alignment method

Info

Publication number: CN111308791B
Application number: CN202010123858.2A
Authority: CN
Inventors: 陆建钢; 黄凯; 冯一凡; 何金蔓
Original assignee: Shanghai Jiaotong University
Current assignee: Shanghai Jiaotong University
Priority date: 2020-02-27
Filing date: 2020-02-27
Publication date: 2021-04-27
Anticipated expiration: 2040-02-27
Also published as: CN111308791A

Abstract

The invention provides a photo-alignment method and a photo-alignment device, which are characterized in that two photo-alignment layers are photo-aligned by using the same exposure light source, a first photo-alignment layer, a first optical rotation medium layer and a second photo-alignment layer are sequentially arranged in the light irradiation direction of the light source, a mask plate is added between the exposure light source and the first photo-alignment layer to control an exposure area, the first optical rotation medium layer is controlled to rotate the polarization direction of light by N degrees, and the photo-alignment of the second photo-alignment layer on the light irradiation path is different from the photo-alignment of the first photo-alignment layer by N degrees. The invention has the advantages of realizing the accurate alignment of the multi-domain micro-area of the polarization-independent liquid crystal device and being simple and convenient.

Description

Photo-alignment method

Technical Field

The invention relates to the field of liquid crystal device preparation, in particular to a photoalignment method.

Background

In recent years, with the development of optical communication technology, the demand for devices in optical communication has been increasing. The use of polarization independent devices can greatly reduce the complexity of optical communication systems. The light-operated micro-domain multi-domain orthogonal orientation liquid crystal device is used as a novel polarization-independent device, the polarization-dependent isolation degree is good, but the preparation is still more complicated. The traditional method is to respectively carry out micro-domain multi-domain exposure on two substrates and then accurately align and assemble the upper substrate and the lower substrate, and the method is complex, has high requirement on process precision and is complicated to prepare. And when the size of the domain is smaller, it is more difficult to realize the precise alignment of the micro-region. Therefore, the traditional micro-domain multi-domain implementation method of the polarization-independent liquid crystal device cannot be commercially produced in a large scale.

Disclosure of Invention

In view of the above-mentioned drawbacks of the prior art, the technical problems to be solved by the present invention are: the method can realize the multi-domain orthogonal orientation of the micro-area of the polarization-independent liquid crystal device and reduce the complexity of the process.

In order to solve the problems, the invention provides a photo-alignment method, which uses the same exposure light source to perform photo-alignment on two photo-alignment layers at the same time, and a first photo-alignment layer, a first optical rotation medium layer and a second photo-alignment layer are sequentially arranged in the light irradiation direction of the light source; the first optical orientation layer and the first optical medium layer are made of light-transmitting materials.

Furthermore, a mask plate is added between the exposure light source and the first photo-alignment layer to control an exposure area.

Further, the first optically active medium layer is controlled to rotate the polarization direction of light by N degrees, so that the optical orientation of the second optical orientation layer on the light irradiation path is different from the optical orientation of the first optical orientation layer by N degrees.

Furthermore, before photo-alignment, pre-exposure treatment is performed on the first photo-alignment layer and the second photo-alignment layer respectively, so that the first photo-alignment layer and the second photo-alignment layer have certain photo-alignment.

Further, after the second optical orientation layer, a second optical rotation medium layer and a third optical orientation layer are placed along the light direction, and the three layers are subjected to optical orientation; and all layers between the second optical rotation medium layer and the exposure light source are made of light-transmitting materials.

Further, when the polarization-independent liquid crystal device is manufactured, the first optical rotation medium layer is controlled to rotate the polarization direction of light by 90 degrees.

Further, when the polarization-independent liquid crystal device is manufactured, the first optical orientation layer, the first optical rotation medium layer and the second optical orientation layer are assembled into a box, after exposure is completed, the first optical rotation medium layer is soaked and washed away, and liquid crystal is filled.

A photo-alignment device comprises a first photo-alignment layer, a first optically active medium layer and a second photo-alignment layer which are sequentially arranged along the propagation direction of exposure light; the first optical orientation layer and the first optical rotation medium layer are made of light-transmitting materials.

Further, the device comprises a mask plate which is arranged between the exposure light source and the first photo-alignment layer, and the mask plate only allows partial areas of exposure light to penetrate through.

Further, the optical rotation medium layer comprises a second optical rotation medium layer and a third optical orientation layer which are sequentially arranged behind the second optical orientation layer along the light direction; the second optical orientation layer and the second optical rotation medium layer are made of light-transmitting materials.

The invention has the advantages of realizing the accurate alignment of the multi-domain micro-area of the polarization-independent liquid crystal device and being simple and convenient.

Drawings

FIG. 1 is a block diagram of an apparatus according to a preferred embodiment of the present invention;

FIG. 2 is a schematic view of the orientation of the upper orientation layer 5 according to a preferred embodiment of the present invention;

FIG. 3 is a schematic view of the orientation of the lower orientation layer 7 according to a preferred embodiment of the present invention;

the device comprises a substrate, an exposure light source, a mask 2, an upper substrate 3, an upper electrode layer 1, an upper alignment layer 5, an optical rotation medium layer 6, a lower alignment layer 7, a lower electrode layer 8 and a lower substrate 9.

Detailed Description

The preferred embodiments of the present invention will be described below with reference to the accompanying drawings for clarity and understanding of technical contents. The present invention may be embodied in many different forms of embodiments and the scope of the invention is not limited to the embodiments set forth herein.

In the drawings, structurally identical elements are represented by like reference numerals, and structurally or functionally similar elements are represented by like reference numerals throughout the several views. The size and thickness of each component shown in the drawings are arbitrarily illustrated, and the present invention is not limited to the size and thickness of each component. The thickness of the components may be exaggerated where appropriate in the figures to improve clarity.

As shown in FIG. 1, the structure of the apparatus of a preferred embodiment of the present invention realizes the multi-domain orthogonal orientation of the micro-domains of the polarization-independent liquid crystal device, which comprises the following components in sequence from top to bottom: the device comprises an exposure light source 1, a mask 2, an upper substrate 3, an upper electrode layer 4, an upper orientation layer 5, an optical rotation medium layer 6, a lower orientation layer 7, a lower electrode layer 8 and a lower substrate 9. The upper substrate 3, the upper electrode layer 4, the upper alignment layer 5 and the optical rotation medium layer 6 are made of transparent materials, so that the exposure light source 1 can reach the lower alignment layer 7. The reticle 2 functions to allow only the exposure light of the uncovered portion to pass therethrough, thereby controlling the exposure area. In the preparation of the polarization independent liquid crystal device, the upper alignment layer 5 and the lower alignment layer 7 are optionally pre-exposed to allow the upper alignment layer 5 and the lower alignment layer 7 to have a certain orientation, and then assembled into a cell in the order shown in fig. 1. When the light orientation is carried out, the light emitted by the exposure light source 1 is irradiated from top to bottom, the light passes through the uncovered part of the mask 2 and then passes through the upper substrate 3 to reach the upper orientation layer 5, the light orientation of the part of the upper orientation layer 5 covered by the mask 2 is not changed, the part uncovered by the mask is irradiated by the light to be reoriented, and the orientation direction of the part is consistent with the polarization direction of the exposure light source 1; the light continues to reach the optically active medium layer 6 downwards, and the polarization direction of the light is rotated due to the optical rotation property of the optically active medium layer 6; and then the rotated light continues to reach the lower orientation layer 7 downwards, and the orientation of the position, which is not covered by the mask, of the lower orientation layer 7 is consistent with the polarization direction of the rotated light. By controlling the voltage between the upper electrode layer 4 and the lower electrode layer 8, the rotation angle of the optically active medium layer 6 with respect to the polarization direction of light can be controlled. In this example, in order to obtain polarization headless characteristics, the rotation angle of the optically active medium layer 6 with respect to the polarization direction of light is controlled to 90 °. After exposure, the material in the optical rotation medium layer 6 is washed away, and the required liquid crystal material is filled in, so that the liquid crystal device with the polarization-independent characteristic can be obtained.

The exposure area can be controlled by the reticle 2. Different mask plates and light sources with different polarization directions can be used for carrying out different-direction light orientation operation on different areas of the orientation layer, and the pre-exposure treatment on the orientation layer is matched, so that different micro-domain multi-domain light orientations can be realized.

As shown in fig. 2, which is a schematic view of the orientation of the upper orientation layer 5 obtained by the above method, the orientation directions of the adjacent grid regions are perpendicular to each other.

As shown in fig. 3, which is a schematic view of the alignment of the lower alignment layer 7 obtained by the above method, the alignment directions of the adjacent grid regions are perpendicular to each other and the alignment directions of the grid regions corresponding to the upper and lower substrates are also perpendicular to each other.

In other embodiments, more layers of optically active media and alignment layers may be placed under the lower substrate 9 to align more layers simultaneously.

The optical orientation method provided by the invention can realize the accurate alignment of the multi-domain micro-area of the polarization-independent liquid crystal device, and is simple and convenient.

The foregoing detailed description of the preferred embodiments of the invention has been presented. It should be understood that numerous modifications and variations could be devised by those skilled in the art in light of the present teachings without departing from the inventive concepts. Therefore, the technical solutions available to those skilled in the art through logic analysis, reasoning and limited experiments based on the prior art according to the concept of the present invention should be within the scope of protection defined by the claims.

Claims

1. A photo-alignment method is characterized in that the same exposure light source is used for photo-alignment of two photo-alignment layers at the same time, and a first photo-alignment layer, a first optical rotation medium layer and a second photo-alignment layer are sequentially arranged in the light irradiation direction of the light source; the first optical orientation layer and the first optical rotation medium layer are made of light-transmitting materials; the first optically active medium layer rotates the polarization direction of light by N degrees, so that the optical orientation of the second optical orientation layer on the light irradiation path is different from the optical orientation of the first optical orientation layer by N degrees.

2. The photoalignment method according to claim 1, wherein a mask plate is interposed between the exposure light source and the first photoalignment layer to control an exposure region.

3. The photoalignment method according to claim 1, wherein the first photoalignment layer and the second photoalignment layer are pre-exposed before photoalignment to allow the first photoalignment layer and the second photoalignment layer to have a predetermined photoalignment.

4. The photoalignment method according to claim 1, wherein after the second photoalignment layer, a second optically active medium layer and a third photoalignment layer are further disposed in the direction of light, and photoalignment is performed on the three layers at the same time; each layer between the second optically active medium layer and the exposure light source is made of a light-transmitting material; the second optical rotation medium layer rotates the polarization direction of light by N degrees.

5. The photoalignment method according to claim 1, wherein the first optically active medium layer is controlled to rotate the polarization direction of light by 90 ° when fabricating the polarization-independent liquid crystal device.

6. The photoalignment method according to claim 1, wherein the first photoalignment layer, the first optically active medium layer, and the second photoalignment layer are assembled into a cell during the fabrication of the polarization-independent liquid crystal device, and after the exposure is completed, the first optically active medium layer is soaked and washed away, and then the liquid crystal is filled.

7. A photo-alignment device is characterized by comprising a first photo-alignment layer, a first optically active medium layer and a second photo-alignment layer which are sequentially arranged along the propagation direction of exposure light; the first optical orientation layer and the first optical rotation medium layer are made of light-transmitting materials; the first optical rotation medium layer is used for rotating the polarization direction of light rays by N degrees, so that the optical orientation of the second optical orientation layer is different from the optical orientation of the first optical orientation layer by N degrees.

8. The photo-alignment device of claim 7, comprising a mask plate disposed between the exposure light source and the first photo-alignment layer, the mask plate allowing only a partial area of the exposure light to pass through.

9. The photo-alignment device according to claim 7, comprising a second optically active medium layer, a third photo-alignment layer, sequentially disposed behind the second photo-alignment layer in the direction of light; the second optical orientation layer and the second optical rotation medium layer are made of light-transmitting materials; the second optical rotation medium layer is used for rotating the polarization direction of light by N degrees.