Electrically controlled optical screen

Abstract

An electrically controlled optical screen includes a switchable scattering element and an electrically controlled decorative module. The switchable scattering element is disposed on one side of the electrically controlled decorative module to switch between a scattering state and a transparent state. The electrically controlled decorative module includes a first polarizing layer, a first quarter wave plate, a cholesteric liquid crystal layer, an electrically controlled wave plate, a second quarter wave plate, and a second polarizing layer which are sequentially stacked. The electrically controlled wave plate has a liquid crystal layer. The second polarizing layer is disposed between the switchable scattering element and the second quarter wave plate. Image light projected to the electrically controlled optical screen can produce an image with high contrast.

Description

Technical Field

[0001] This invention relates to an optical device, and more particularly to an electro-optical screen. Background Technology

[0002] Known projection devices project a beam of light onto a projection screen. The beam is then scattered by the screen and enters the viewer's eye, allowing them to see the image. Projection screens are not limited to common projection screens; they can also be, for example, glass display windows or billboards. Furthermore, the optical performance of a projection screen can be achieved through electronic control, specifically by electronically controlled scattering elements. These electronically controlled scattering elements, for example, utilize polymer-dispersed liquid crystal (PDLC) technology, allowing them to switch between a scattering state and a transparent state. However, electronically controlled scattering elements cannot block light; if the non-projection side is in a bright environment, poor image contrast will occur.

[0003] The "Background Art" paragraph is only used to help understand the content of this invention. Therefore, the content disclosed in the "Background Art" paragraph may include some known technologies that are not known to those skilled in the art. The content disclosed in the "Background Art" paragraph does not mean that the content or the problems to be solved by one or more embodiments of this invention were known or understood by those skilled in the art prior to this application. Summary of the Invention

[0004] The present invention provides an electronically controlled optical screen, comprising an electronically controlled scattering element and an electronically controlled decorative module. The electronically controlled decorative module can block the light from the non-projection side of the electronically controlled scattering element, and the image light projected onto the electronically controlled optical screen can produce a high-contrast image.

[0005] Other objects and advantages of the present invention can be further understood from the technical features disclosed herein.

[0006] To achieve one or more of the above-mentioned objectives or other objectives, according to an embodiment of the present invention, an electro-optical screen is provided, including a switchable scattering element and an electro-optical decorative module. The electro-optical screen is used to switch between different optical modes. The switchable scattering element is disposed on one side of the electro-optical decorative module for switching between a scattering state and a transparent state. The electro-optical decorative module includes a first polarizing layer, a first quarter-wave plate, a cholesteric liquid crystal layer, an electro-optical wave plate, a second quarter-wave plate, and a second polarizing layer arranged in sequence. The electro-optical wave plate includes a liquid crystal layer. The second polarizing layer is disposed between the switchable scattering element and the second quarter-wave plate. The cholesteric liquid crystal layer is used to reflect either left-handed or right-handed circularly polarized light. The light absorption axis of the first polarizing layer is perpendicular to the light absorption axis of the second polarizing layer, and the optical axis of the first quarter-wave plate is parallel to the optical axis of the second quarter-wave plate; or the light absorption axis of the first polarizing layer is parallel to the light absorption axis of the second polarizing layer, and the optical axis of the first quarter-wave plate is perpendicular to the optical axis of the second quarter-wave plate.

[0007] According to an embodiment of the present invention, an electro-optical screen is provided, including a scattering element and an electro-optical decorative module. The electro-optical screen is used to switch between different optical modes. The scattering element is disposed on one side of the electro-optical decorative module. The electro-optical decorative module includes a first polarizing layer, a first quarter-wave plate, a cholesteric liquid crystal layer, an electro-optical wave plate, a second quarter-wave plate, and a second polarizing layer, which are sequentially stacked. The first polarizing layer is disposed between the scattering element and the first quarter-wave plate, and the cholesteric liquid crystal layer is used to reflect either left-handed or right-handed circularly polarized light. The light absorption axis of the first polarizing layer is perpendicular to the light absorption axis of the second polarizing layer, and the optical axis of the first quarter-wave plate is parallel to the optical axis of the second quarter-wave plate; alternatively, the light absorption axis of the first polarizing layer is parallel to the light absorption axis of the second polarizing layer, and the optical axis of the first quarter-wave plate is perpendicular to the optical axis of the second quarter-wave plate.

[0008] Based on the above, the electro-optical screen provided in this embodiment of the invention includes an electro-optical scattering element and an electro-optical decorative module for switching between different optical modes. More specifically, the switchable scattering element can switch between a scattering state and a transparent state, and is used in conjunction with an electro-optical waveplate in the electro-optical decorative module to generate multiple optical modes. These various optical modes provide users with different visual experiences.

[0009] To make the above features and advantages of the present invention more apparent and understandable, specific embodiments are described below in conjunction with the accompanying drawings. Attached Figure Description

[0010] Figure 1 This is a schematic diagram of an electro-optical screen according to an embodiment of the present invention.

[0011] Figure 2AThis is a schematic diagram of the optical mechanism of an electro-optical screen in projection mode according to an embodiment of the present invention.

[0012] Figure 2B This is a schematic diagram of an electro-optical screen according to an embodiment of the present invention.

[0013] Figure 2C This is a schematic diagram of an electro-optical screen according to an embodiment of the present invention.

[0014] Figure 2D This is a schematic diagram of a projection device according to an embodiment of the present invention.

[0015] Figure 3 This is a schematic diagram of the optical mechanism of an electro-optical screen in decorative mode according to an embodiment of the present invention.

[0016] Figure 4 This is a schematic diagram of the optical mechanism of an electro-optical screen in transparent mode according to an embodiment of the present invention.

[0017] Figure 5 This is a schematic diagram of the optical mechanism of the electro-optical screen in light-collecting mode according to an embodiment of the present invention.

[0018] Figure 6 This is a schematic diagram of the optical mechanism of an electro-optical screen in projection mode according to an embodiment of the present invention.

[0019] Figure 7 This is a schematic diagram of an electro-optical screen according to an embodiment of the present invention.

[0020] Figure 8 This is a schematic diagram of the optical mechanism of an electro-optical screen in projection mode according to an embodiment of the present invention.

[0021] Figure 9 This is a schematic diagram of the optical mechanism of an electro-optical screen in decorative mode according to an embodiment of the present invention.

[0022] Figure 10 This is a schematic diagram of an electro-optical screen according to an embodiment of the present invention.

[0023] Figure 11 This is a schematic diagram of an electro-optical screen according to an embodiment of the present invention.

[0024] Figure 12 This is a schematic diagram of a cholesterol liquid crystal layer according to an embodiment of the present invention.

[0025] Figure 13 This is a schematic diagram illustrating the preparation of a cholesterol liquid crystal layer according to an embodiment of the present invention.

[0026] Explanation of reference numerals in the attached figures:

[0027] 1: Projection System

[0028] 20: Projection device

[0029] 20I: Image Light

[0030] 30: Reflector

[0031] 10A, 10B, 10C, 10D, 10E, 10F, 10G: Electro-controlled optical screens

[0032] 100, 100D, 100F: Electrically controlled decorative modules

[0033] 101: Electronically controlled waveplate

[0034] 102: Cholesterol liquid crystal layer

[0035] 1021: Cholesterol Liquid Crystal Molecules

[0036] 200: Switchable scattering element

[0037] 300: Scattering element

[0038] 400: Fresnel lens layer

[0039] 401: Semi-transparent and semi-reflective layer

[0040] 500: Diffusion layer

[0041] 600: Hard surface layer

[0042] 700: Prism layer

[0043] 701: Reflective layer

[0044] 702: Light-absorbing layer

[0045] 800: Imprint plate

[0046] C1, C2, C11: Ambient Light

[0047] H1: O-plate optical compensation film

[0048] H2: Compensation membrane

[0049] OA: Optical Axis

[0050] CA: Helical shaft

[0051] P1: First polarizing layer

[0052] P2: Second polarizing layer

[0053] P3: Reflective polarizing layer

[0054] Q1: First 1 / 4 wave plate

[0055] Q2: Second quarter wave plate

[0056] X, Y, Z: Direction Detailed Implementation

[0057] The foregoing descriptions and other technical contents, features, and effects of this invention will be clearly presented in the following detailed description of a preferred embodiment with reference to the accompanying drawings. The directional terms used in the following embodiments, such as up, down, left, right, front, or back, are merely for reference to the accompanying drawings. Therefore, the directional terms used are for illustrative purposes and not for limiting the invention.

[0058] Reference Figure 1 The diagram illustrates an electro-optical screen according to an embodiment of the present invention. The electro-optical screen 10A includes a switchable scattering element 200 and an electro-optical decorative module 100. The switchable scattering element 200 is disposed on one side of the electro-optical decorative module 100, which is the projection side of the electro-optical screen 10A, for receiving image beams. The switchable scattering element 200 can be controlled to switch between a scattering state and a transparent state. The electro-optical decorative module 100 includes a first polarizing layer P1, a first quarter-wave plate Q1, a cholesteric liquid crystal layer 102, an electro-optical wave plate 101, a second quarter-wave plate Q2, and a second polarizing layer P2, sequentially stacked. The electro-optical wave plate 101 includes a liquid crystal layer. The second polarizing layer P2 is disposed between the switchable scattering element 200 and the second quarter-wave plate Q2. The light absorption axis of the first polarizing layer P1 is perpendicular to the light absorption axis of the second polarizing layer P2. In this embodiment, the light absorption axis of the first polarizing layer P1 is parallel to the X direction, and the light absorption axis of the second polarizing layer P2 is parallel to the Z direction. The optical axis of the first quarter-wave plate Q1 is parallel to the optical axis of the second quarter-wave plate Q2. The cholesteric liquid crystal layer 102 is used to reflect either left-handed or right-handed circularly polarized light.

[0059] The first quarter-wave plate Q1 and the second quarter-wave plate Q2 can be made of materials with normal wavelength dispersion or inverse wavelength dispersion, preferably materials with inverse wavelength dispersion. The cholesteric liquid crystal layer 102 possesses cholesteric liquid crystal and can have decorative patterns, such as wood grain. Specifically, cholesteric liquid crystal is a liquid crystal molecule with Bragg reflection and bistable properties. It can reflect incident light with a wavelength equal to its pitch and the same optical rotation. Under the drive of an applied electric field, it can switch between two stable states: a planar state and a focal-conic state. In the planar state, cholesteric liquid crystal reflects light of a specific wavelength, thus displaying its decorative pattern; in the focal-conic state, light passes through without displaying its decorative pattern. For ease of understanding, in this invention… Figures 1 to 9 In the described embodiment, the cholesterol liquid crystal layer 102 is configured to reflect left-handed circularly polarized light, while right-handed circularly polarized light will pass through the cholesterol liquid crystal layer 102.

[0060] In some embodiments, the switchable scattering element 200 includes a liquid crystal layer. The liquid crystal molecules in the liquid crystal layer are, for example, polymer-dispersed liquid crystal (PDLC), polymer network liquid crystal (PNLC), or multi-stable liquid crystal (MSLC), so that the switchable scattering element 200 can switch between a scattering state (foggy state) and a transparent state.

[0061] The electrically controlled waveplate 101 can be a liquid crystal cell employing Vertical Alignment (VA) technology, Electrically Controlled Birefringence (ECB) technology, or In-Plane Switching (IPS) technology. Taking an embodiment employing Vertical Alignment (VA) technology as an example, the electrically controlled waveplate 101 can switch between a half-waveplate state and a state without phase delay by applying or not applying voltage. Based on the structure and technology of the switchable scattering element 200 and the electrically controlled waveplate 101 described above, the electrically controlled optical screen 10A can switch between different optical modes, as described below. For example, the electrically controlled optical screen 10A can switch between projection mode, decorative mode, transparent mode, and light-receiving mode, as detailed below.

[0062] Simultaneously refer to Figure 1 , Figure 2A as well as Figure 2D . Figure 2D These are schematic diagrams of projection devices according to some embodiments of the present invention. Figure 2A yes Figure 1 A schematic diagram of the optical mechanism of the electro-optical screen 10A in projection mode is shown below. In this embodiment, the projection system 1 includes an electro-optical screen 10A, a projection device 20, and a reflector 30. The projection device 20 provides image light 20I. The image light 20I projected from the projection device 20 is reflected by the reflector 30 and then projected onto the electro-optical screen 10A. In this embodiment, the projection device 20 and the electro-optical screen 10A are disposed on the same side of the reflector 30, and the image light 20I is incident from the projection side of the electro-optical screen 10A. The reflector 30 may be, for example, a separately configured reflector or a reflector disposed in the same housing as the projection device.

[0063] In various embodiments of the present invention, the image light 20I is configured to be obliquely incident on the electrically controlled optical screen 10A (or the electrically controlled optical screens 10B to 10E as described in other embodiments), such as Figure 2D As shown. Specifically, after the image light 20I is emitted from the projection device 20, it is reflected by the reflector 30 to the electro-optical screen 10A. There is a gap between the image light 20I and the projection device 20 between the reflector 30 and the electro-optical screen 10A. This gap is limited by an offset. If the offset is too small, the image light 20I will interfere with the lens of the projection device 20. The offset is (h+h')×100% / h, where h' is the perpendicular distance between the lower edge of the projected image on the electro-optical screen 10A and the extension line of the optical axis OA of the projection device 20, and h is the length of the projected image on the electro-optical screen 10A in the direction perpendicular to the extension line of the optical axis OA. Preferably, the offset should be greater than or equal to 120%.

[0064] In this embodiment, when the electro-optical screen 10A switches to projection mode, the switchable scattering element 200 disposed on the projection side of the electro-optical screen 10A is configured in scattering state, and the electro-optical waveplate 101 is configured as a half-wave plate (half-wave plate state).

[0065] When image light 20I from projection device 20 is incident on switchable scattering element 200 from the projection side of electro-optical screen 10A, a portion of the image light 20I is reflected and scattered to form a projected image seen by the human eye located on the projection side. Another portion of the image light 20I is penetrated and scattered, then sequentially penetrates the second polarizing layer P2, the second quarter-wave plate Q2, the electro-optical wave plate 101, and the cholesteric liquid crystal layer 102. Since most of this portion of image light 20I is obliquely incident on the cholesteric liquid crystal layer 102, and for image light obliquely incident on the cholesteric liquid crystal layer 102, the reflection spectrum of the cholesteric liquid crystal layer 102 shifts towards shorter wavelengths (i.e., the blue band), its reflectivity is significantly reduced, allowing most of the light to penetrate the cholesteric liquid crystal layer 102 and be absorbed by the first polarizing layer P1.

[0066] Next, the effects of the electro-optical screen 10A on the ambient light C1 from the projection side and the ambient light C2 from the non-projection side will be described in detail. The projection side of the electro-optical screen 10A is the side on which the electro-optical screen 10A receives the image light, and the non-projection side of the electro-optical screen 10A is the other side opposite to the projection side.

[0067] The electro-optical screen 10A operates in projection mode. Ambient light C1 from the projection side travels towards the switchable scattering element 200. A portion of the ambient light C1 penetrates the switchable scattering element 200 and is scattered by it. The remaining portion is scattered and reflected by the surface of the switchable scattering element 200. The portion of ambient light C1 that penetrates the switchable scattering element 200 becomes linearly polarized in the X direction after penetrating the second polarizing layer P2. After penetrating the second quarter-wave plate Q2, the ambient light C1 becomes right-handed circularly polarized, and after penetrating the electro-optical waveplate 101 (configured as a half-wave plate), it becomes left-handed circularly polarized C1. When this left-handed circularly polarized C1 is incident on the cholesteric liquid crystal layer 102, a portion is reflected by the cholesteric liquid crystal layer 102 to form ambient light C11, while the remaining portion penetrates the cholesteric liquid crystal layer 102 because its wavelength deviates from the dominant wavelength corresponding to the cholesteric liquid crystal molecules. After passing through the first quarter-wave plate Q1, the ambient light C1 that passes through the cholesterol liquid crystal layer 102 is formed as linearly polarized light in the X direction and is absorbed by the first polarizing layer P1.

[0068] After being reflected by the cholesteric liquid crystal layer 102, the ambient light C11 is formed as right-handed circularly polarized light C11 after passing through the electrically controlled waveplate 101 (configured as a half-wave plate). After passing through the second quarter-wave plate Q2, the ambient light C11 reflected by the cholesteric liquid crystal layer 102 is formed as X-direction linearly polarized light and passes through the second polarizing layer P2. Finally, the ambient light C11 is scattered by the switchable scattering element 200. At this point, the brightness of the ambient light C11 has been significantly reduced compared to the initial brightness of the ambient light C1.

[0069] Ambient light C2 from the non-projection side is linearly polarized in the Z direction after passing through the first polarizing layer P1. After passing through the first quarter-wave plate Q1, it is formed into right-hand circularly polarized light C2 and can then penetrate the cholesteric liquid crystal layer 102. The right-hand circularly polarized light C2 is formed into left-hand circularly polarized light after passing through the electrically controlled wave plate 101 (configured as a half-wave plate). After passing through the second quarter-wave plate Q2, ambient light C2 is formed into linearly polarized light in the Z direction and is absorbed by the second polarizing layer P2. Therefore, ambient light C2 cannot transmit through the electrically controlled optical screen 10A, significantly reducing the impact of ambient light C2 from the non-projection side on the quality of the projected image.

[0070] Based on the above, when the electro-optical screen 10A is switched to projection mode, the switchable scattering element 200 is configured in scattering mode, and the electro-optical waveplate 101 is configured as a half-wave plate. The electro-optical screen 10A can greatly avoid the influence of ambient light C2 from the non-projection side and ambient light C1 from the projection side on the quality of the projected image.

[0071] To fully illustrate the various embodiments of the present invention, other embodiments will be described below. It must be noted that the following embodiments use the same element reference numerals and some content as those in the foregoing embodiments, with the same reference numerals representing the same or similar elements, and descriptions of identical technical content omitted. For explanations of the omitted parts, please refer to the foregoing embodiments; these will not be repeated in the following embodiments.

[0072] Simultaneously refer to Figure 1 , Figure 2B as well as Figure 2D . Figure 2B This is a schematic diagram of an electro-optical screen according to an embodiment of the present invention. In this embodiment, the projection system 1 includes an electro-optical screen 10B, a projection device 20, and a reflector 30, wherein the reflector 30 may be, for example, a separately configured reflector or a reflector configured in the same housing as the projection device 20. The projection device 20 is used to provide image light 20I. After being reflected by the reflector 30, the image light 20I is projected from the projection side of the electro-optical screen 10B onto the electro-optical screen 10B.

[0073] In this embodiment, the electro-optical screen 10B differs from the electro-optical screen 10A in that it further includes a Fresnel lens layer 400, and a transmissive and reflective layer 401 is coated on the Fresnel lens layer 400. The transmissive and reflective layer 401 is, for example, coated on at least a portion of the surface of the Fresnel lens layer 400 away from the switchable scattering element 200. Image light 20I is reflected by the transmissive and reflective layer 401 and then enters the human eye, improving visibility and contrast. In one embodiment, the transmissive and reflective layer 401 can be replaced by a reflective layer with higher reflectivity.

[0074] In another embodiment, the electro-optical screen 10B further includes a hard surface layer 600 and a diffusion layer 500, with the diffusion layer 500 disposed, for example, between the hard surface layer 600 and the Fresnel lens layer 400. After the image light 20I penetrates the hard surface layer 600 and the diffusion layer 500, at least a portion of the image light 20I is reflected by the semi-transparent and semi-reflective layer 401 and sequentially penetrates the diffusion layer 500 and the hard surface layer 600 before entering the human eye. A switchable scattering element 200 is used as a substrate and is used to scatter and reflect the remaining portion of the image light 20I that has penetrated the semi-transparent and semi-reflective layer 401 and the Fresnel lens layer 400 to avoid glare. The hard surface layer 600 is used to protect the electro-optical screen 10B, has scratch-resistant properties, and can be made of transparent glass or plastic.

[0075] Simultaneously refer to Figure 1 , Figure 2C as well as Figure 2D . Figure 2C This is a schematic diagram of an electro-optical screen according to an embodiment of the present invention. In this embodiment, the projection system 1 includes an electro-optical screen 10C, a projection device 20, and a reflector 30, wherein the reflector 30 may be, for example, a separately configured reflector or a reflector configured in the same housing as the projection device 20. The projection device 20 is used to provide image light 20I. After being reflected by the reflector 30, the image light 20I is projected from the projection side onto the electro-optical screen 10C.

[0076] In this embodiment, the electro-optical screen 10C differs from the electro-optical screen 10A in that the electro-optical screen 10B further includes a prism layer 700. The prism layer 700 comprises a plurality of prism structures arranged along the X-direction. A reflective layer 701 and a light-absorbing layer 702 are respectively coated on the surface of each prism structure of the prism layer away from the switchable scattering element, and the reflective layer 701 and the light-absorbing layer 702 are alternately arranged. The reflective layer 701 is disposed on the light-facing surface of each prism structure of the prism layer 700.

[0077] Image light 20I is reflected by the reflective layer 701 on the light-facing surface of the prism structure and then enters the human eye, increasing the visibility and contrast of image light 20I. Ambient light is absorbed by the light-absorbing layer 702 on the prism structure to improve image contrast. A switchable scattering element 200 is used as a substrate and scatters and reflects a small portion of the image light 20I that penetrates the prism layer 700.

[0078] Simultaneously refer to Figure 1 as well as Figure 3 . Figure 3 yes Figure 1 A schematic diagram of the optical mechanism of the electro-optical screen 10A in decorative mode.

[0079] In this embodiment, when the electro-optical screen 10A is switched to the decorative mode, the switchable scattering element 200 is configured to a transparent state, and the electro-optical waveplate 101 is configured as a half-wave plate (half-wave plate state).

[0080] Ambient light C2 from the non-projection side of the electro-optical screen 10A is linearly polarized in the Z direction after passing through the first polarizing layer P1. After passing through the first quarter-wave plate Q1, it is formed into right-hand circularly polarized light C2 and can then penetrate the cholesteric liquid crystal layer 102. The right-hand circularly polarized light C2 is formed into left-hand circularly polarized light after passing through the electro-optical waveplate 101 (configured as a half-wave plate). After passing through the second quarter-wave plate Q2, the ambient light C2 is formed into linearly polarized light in the Z direction and is absorbed by the second polarizing layer P2.

[0081] Ambient light C1 from the projection side of the electro-optical screen 10A travels towards the switchable scattering element 200, penetrates the switchable scattering element 200, and forms linearly polarized light in the X direction after passing through the second polarizing layer P2. After passing through the second quarter-wave plate Q2, ambient light C1 forms right-hand circularly polarized light, and after passing through the electro-optical waveplate 101 (configured as a half-wave plate), it forms left-hand circularly polarized light C1. When this left-hand circularly polarized light C1 is incident on the cholesteric liquid crystal layer 102, a portion of it is reflected by the cholesteric liquid crystal layer 102 to form ambient light C11, while the other portion of the left-hand circularly polarized light C1 penetrates the cholesteric liquid crystal layer 102 because its wavelength deviates from the dominant wavelength corresponding to the cholesteric liquid crystal molecules. After passing through the first quarter-wave plate Q1, the ambient light C1 that has penetrated the cholesteric liquid crystal layer 102 forms linearly polarized light in the X direction and is absorbed by the first polarizing layer P1.

[0082] After being reflected by the cholesteric liquid crystal layer 102, the ambient light C11 is formed as right-hand circularly polarized light C11 after passing through the electrically controlled waveplate 101 (configured as a half-wave plate). After passing through the second quarter-wave plate Q2, the ambient light C11 is formed as X-direction linearly polarized light and passes through the second polarizing layer P2. Finally, it passes through the transparent switchable scattering element 200, making the decorative pattern (e.g., wood grain) of the cholesteric liquid crystal layer 102 visible to the human eye.

[0083] Simultaneously refer to Figure 1 as well as Figure 4 . Figure 4 yes Figure 1 A schematic diagram of the optical mechanism of the electro-optical screen 10A in transparent mode.

[0084] In this embodiment, the electro-optical screen 10A is switched to a transparent mode, wherein the switchable scattering element 200 is configured to be transparent and the electro-optical waveplate 101 is configured to be in a state without phase delay.

[0085] Ambient light C2 from the non-projection side of the electro-optical screen 10A is linearly polarized in the Z direction after passing through the first polarizing layer P1. After passing through the first quarter-wave plate Q1, it is formed into right-hand circularly polarized light C2, which can then penetrate the cholesteric liquid crystal layer 102. The right-hand circularly polarized light C2 remains right-hand circularly polarized after passing through the electro-optical wave plate 101 (without phase delay function). After passing through the second quarter-wave plate Q2, ambient light C2 is linearly polarized in the X direction, which can then penetrate the second polarizing layer P2 and the transparent switchable scattering element 200.

[0086] Ambient light C1 from the projection side of the electro-optical screen 10A travels towards the switchable scattering element 200, penetrates the switchable scattering element 200, and forms linearly polarized light in the X direction after passing through the second polarizing layer P2. After passing through the second quarter-wave plate Q2, ambient light C1 forms right-hand circularly polarized light, and remains right-hand circularly polarized light C1 after passing through the electro-optical wave plate 101 (without phase delay function), thus penetrating the cholesteric liquid crystal layer 102. After passing through the first quarter-wave plate Q1, ambient light C1 forms linearly polarized light in the Z direction, thus penetrating the first polarizing layer P1. Therefore, when the electro-optical screen 10A is in transparent mode, ambient light incident from both opposite sides of the electro-optical screen 10A will pass through the electro-optical screen 10A.

[0087] Simultaneously refer to Figure 1 as well as Figure 5 . Figure 5 yes Figure 1 A schematic diagram of the optical mechanism of the electro-optical screen 10A in light-collecting mode.

[0088] In this embodiment, the electro-optical screen 10A is switched to a light-collecting mode, wherein the switchable scattering element 200 is configured in a scattering state, and the electro-optical waveplate 101 is configured to have no phase delay function. This embodiment is similar to... Figure 4 The difference in the transparent mode shown is that both ambient light C1 and ambient light C2 are scattered by the switchable scattering element 200 of the electro-optical screen 10A, which has an anti-peeping effect.

[0089] Reference Figure 6 as well as Figure 2D , Figure 6 A schematic diagram of an electro-optical screen according to an embodiment of the present invention is shown. Compared to the electro-optical screen 10A, the electro-optical decorative module 100D of the electro-optical screen 10D includes a reflective polarizing layer P3 and an O-plate optical compensation film H1. The reflective polarizing layer P3 is disposed between the second quarter-wave plate Q2 and the second polarizing layer P2, and the O-plate optical compensation film H1 is disposed between the second polarizing layer P2 and the reflective polarizing layer P3. In this embodiment, the reflection axis of the reflective polarizing layer P3 is parallel to the light absorption axis of the second polarizing layer P2, and both are parallel to the Z direction, but the present invention is not limited thereto.

[0090] and Figure 2A Similar to the illustrated embodiment, a portion of the image light 20I is reflected and scattered by the switchable scattering element 200 to form a projected image seen by the human eye. In addition, a portion of the image light 20I that penetrates the switchable scattering element 200 will (at least partially) penetrate the second polarizing layer P2 and the O-plate optical compensation film H1, forming linearly polarized light in the Z direction. After the linearly polarized light penetrating the O-plate optical compensation film H1 is reflected by the reflective polarizing layer P3, it penetrates the O-plate optical compensation film H1 again, forming linearly polarized light that can penetrate the second polarizing layer P2. This linearly polarized light can then penetrate the switchable scattering element 200 again, thereby effectively increasing the amount of image light 20I incident on the human eye and improving contrast.

[0091] In some embodiments, the O-plate optical compensation film H1 can be replaced by two A-plates or C-plates that are perpendicular to the optical axis.

[0092] It should be noted that, in Figures 1 to 6 In this embodiment, the optical axis of the first quarter-wave plate Q1 can also be perpendicular to the optical axis of the second quarter-wave plate Q2, and the light absorption axis of the first polarizing layer P1 and the light absorption axis of the second polarizing layer P2 are parallel to each other. Since the optical axis of the first quarter-wave plate Q1 is perpendicular to the optical axis of the second quarter-wave plate Q2, the color shift phenomenon will be reduced.

[0093] In some embodiments, the cholesteric liquid crystal layer 102 of the electro-optical screens 10A, 10B, 10C, and 10D is dextrorotatory cholesteric liquid crystal, and the optical axis of the first quarter-wave plate Q1 is rotated 90 degrees with the slow axis of the second quarter-wave plate Q2, so that the ambient light becomes left-handed circularly polarized light after passing through the first polarizing layer P1 and the first quarter-wave plate Q1 or through the second polarizing layer P2 and the second quarter-wave plate Q2, so that the ambient light can pass through the cholesteric liquid crystal layer 102 to hide the decorative pattern of the cholesteric liquid crystal layer 102, and so that the electro-optical screens present a transparent mode.

[0094] Reference Figure 7 as well as Figure 2D , Figure 7 A schematic diagram of an electro-optical screen according to an embodiment of the present invention is shown. The electro-optical screen 10E includes a scattering element 300 and an electro-optical decorative module 100. The scattering element 300 is disposed on one side of the electro-optical decorative module 100, and this side is the non-projection side of the electro-optical screen 10E. The electro-optical decorative module 100 includes a first polarizing layer P1, a first quarter-wave plate Q1, a cholesteric liquid crystal layer 102, an electro-optical wave plate 101, a second quarter-wave plate Q2, and a second polarizing layer P2, which are sequentially stacked. The first polarizing layer P1 is located between the scattering element 300 and the first quarter-wave plate Q1. The electro-optical wave plate 101 includes a liquid crystal layer. The light absorption axis of the first polarizing layer P1 is perpendicular to the light absorption axis of the second polarizing layer P2. In this embodiment, the light absorption axis of the first polarizing layer P1 is parallel to the X direction, and the light absorption axis of the second polarizing layer P2 is parallel to the Z direction. The optical axis of the first quarter-wave plate Q1 is parallel to the optical axis of the second quarter-wave plate Q2. The cholesterol liquid crystal layer 102 is used to reflect either left-handed or right-handed circularly polarized light.

[0095] The electrically controlled waveplate 101 can be a liquid crystal cell employing Vertical Alignment (VA) technology, Electrically Controlled Birefringence (ECB) technology, or In-Plane Switching (IPS) technology. Taking an embodiment employing Vertical Alignment (VA) technology as an example, the electrically controlled waveplate 101 can switch between a half-waveplate state and a state without phase delay by applying or not applying voltage. Based on the structure and technology of the electrically controlled waveplate 101 described above, the electrically controlled optical screen 10E can switch between different optical modes, as described below. For example, the electrically controlled optical screen 10E can switch between a projection mode and a decorative mode, as detailed below.

[0096] Simultaneously refer to Figure 2D , Figure 7 as well as Figure 8 . Figure 8 yes Figure 7 A schematic diagram of the optical mechanism of the electro-optical screen 10E in projection mode is shown below. In this embodiment, the projection system 1 includes an electro-optical screen 10E, a projection device 20, and a reflector 30. The projection device 20 provides image light 20I. After being reflected by the reflector 30, the image light 20I is projected onto the electro-optical screen 10E from the projection side. The reflector 30 may be, for example, a separately configured reflector or a reflector configured in the same housing as the projection device.

[0097] In this embodiment, the electro-optical screen 10E is switched to projection mode, wherein the electro-optical waveplate 101 is configured to be in a state without phase retardation. The image light 20I (linearly polarized light in the X direction) from the projection device 20 penetrates the second polarizing layer P2. After penetrating the second quarter waveplate Q2, the image light 20I is formed into right-hand circularly polarized light. Since the electro-optical waveplate 101 is configured to be in a state without phase retardation, the image light 20I remains right-hand circularly polarized light after penetrating the electro-optical waveplate 101, and thus can penetrate the cholesteric liquid crystal layer 102. The right-hand circularly polarized light 20I is formed into linearly polarized light in the Z direction after penetrating the first quarter waveplate Q1, and thus can penetrate the first polarizing layer P1, and is further reflected and scattered by the scattering element 300. The image light 20I reflected and scattered by the scattering element 300 then sequentially penetrates the first polarizing layer P1, the first quarter wave plate Q1, the cholesteric liquid crystal layer 102, the electrically controlled wave plate 101, the second quarter wave plate Q2, and the second polarizing layer P2, forming the image light 20I that enters the human eye.

[0098] Simultaneously refer to Figure 7 as well as Figure 9 . Figure 9 yes Figure 7 A schematic diagram of the optical mechanism of the electro-optical screen 10E in decorative mode.

[0099] In this embodiment, the electro-optical screen 10E is switched to a decorative mode, wherein the electro-optical waveplate 101 is configured as a half-wave plate. Ambient light C1 from the projection side is linearly polarized in the X direction after passing through the second polarizing layer P2. After passing through the second quarter-wave plate Q2, ambient light C1 is formed as right-hand circularly polarized light, and after passing through the electro-optical waveplate 101 (configured as a half-wave plate), it is formed as left-hand circularly polarized light C1. When this left-hand circularly polarized light C1 is incident on the cholesteric liquid crystal layer 102, most of it is reflected by the cholesteric liquid crystal layer 102 to form left-hand circularly polarized light C11, while another part of the left-hand circularly polarized light C1 will pass through the cholesteric liquid crystal layer 102 (not shown) because its wavelength is deviated from the dominant wavelength corresponding to the cholesteric liquid crystal molecules. The left-hand circularly polarized light that passes through the cholesteric liquid crystal layer 102 is linearly polarized in the X direction after passing through the first quarter-wave plate Q1 and is absorbed by the first polarizing layer P1 (not shown).

[0100] After being reflected by the cholesteric liquid crystal layer 102, the left-handed circularly polarized light C11 is transformed into right-handed circularly polarized light C11 after passing through the electrically controlled waveplate 101 (configured as a half-wave plate). After passing through the second quarter-wave plate Q2, the right-handed circularly polarized light C11 is transformed into X-direction linearly polarized light and passes through the second polarizing layer P2, making the decorative pattern of the cholesteric liquid crystal layer 102 visible to the human eye.

[0101] Reference Figure 10 as well as Figure 2D , Figure 10 A schematic diagram of an electro-optical screen according to an embodiment of the present invention is shown. The electro-optical screen 10F includes a switchable scattering element 200 and an electro-optical decorative module 100F. Compared to Figure 1 The electrically controlled decorative module 100F of the electrically controlled optical screen 10A and 10F also includes a compensation film H2, which is disposed between the first quarter wave plate Q1 and the second quarter wave plate Q2 to compensate for the out-of-plane retardation (Rth) of the cholesterol liquid crystal layer 102.

[0102] Specifically, because cholesteric liquid crystals have an out-of-plane phase difference, the phase retardation provided by the cholesteric liquid crystal layer 102 varies with the angle and wavelength of the incident light. Therefore, light with different incident angles and / or different wavelengths is absorbed at different proportions by the first polarizing layer P1 and the second polarizing layer P2 after passing through the cholesteric liquid crystal layer 102, resulting in a color change in the transmitted light. Therefore, this embodiment uses a compensation film H2 to compensate for the out-of-plane phase difference of the cholesteric liquid crystal layer 102, thereby eliminating the aforementioned color shift phenomenon.

[0103] According to some embodiments of the present invention, when the sum of the out-of-plane phase difference of the compensation film H2 and the out-of-plane phase difference of the cholesteric liquid crystal layer 102 is less than 100 nm, better color performance can be obtained; when it is less than 50 nm, even better color performance can be obtained.

[0104] According to some embodiments of the present invention, the compensation film H2 can be a C-plate (e.g., a positive C-plate) or an O-plate, etc., and its out-of-plane phase difference value can cancel out the out-of-plane phase difference value of the cholesteric liquid crystal layer 102. According to some embodiments of the present invention, the cholesteric liquid crystal layer 102 has a decorative pattern, and the pattern of the compensation film H2 is the same as and overlaps with the decorative pattern of the cholesteric liquid crystal layer 102. If the patterns are different or do not overlap, the out-of-plane phase difference value of the compensation film H2 and the out-of-plane phase difference value of the cholesteric liquid crystal layer 102 will not be able to cancel each other out.

[0105] When considering both the out-of-plane phase difference of the first quarter-wave plate Q1 and the out-of-plane phase difference of the second quarter-wave plate Q2, according to some embodiments of the present invention, a better color performance can be obtained when the sum of the out-of-plane phase difference of the compensation film H2, the out-of-plane phase difference of the cholesteric liquid crystal layer 102, the out-of-plane phase difference of the first quarter-wave plate Q1, and the out-of-plane phase difference of the second quarter-wave plate Q2 is less than 100 nm, and an even better color performance can be obtained when it is less than 50 nm.

[0106] According to some embodiments of the present invention, the cholesterol liquid crystal layer 102 has a decorative pattern, and the pattern of the compensation film H2, the pattern of the first quarter wave plate Q1, and the pattern of the second quarter wave plate Q2 are the same as and overlap with the decorative pattern of the cholesterol liquid crystal layer 102. If the patterns are different or do not overlap, the out-of-plane phase difference value of the compensation film H2, the out-of-plane phase difference value of the first quarter wave plate Q1, the out-of-plane phase difference value of the second quarter wave plate Q2, and the out-of-plane phase difference value of the cholesterol liquid crystal layer 102 will not be able to cancel each other out.

[0107] Please refer to the following. Figure 11 as well as Figure 2D , Figure 11 A schematic diagram of an electro-optical screen according to an embodiment of the present invention is shown. The electro-optical screen 10G includes a scattering element 300 and an electro-optical decorative module 100F. The scattering element 300 is disposed on one side of the electro-optical decorative module 100F, and this side is the non-projection side of the electro-optical screen 10G. Compared to Figure 7 The electrically controlled decorative module 100F of the electrically controlled optical screen 10E and the electrically controlled optical screen 10G shown is equipped with a compensation film H2 to compensate for the out-of-plane phase difference of the cholesterol liquid crystal layer 102, or to further compensate for the out-of-plane phase difference of the first quarter wave plate Q1 and the out-of-plane phase difference of the second quarter wave plate Q2. The compensation mechanism is as described above and will not be repeated here.

[0108] Please refer to the following. Figure 12 as well as Figure 13 , Figure 12 This is a schematic diagram of a cholesterol liquid crystal layer according to an embodiment of the present invention, and Figure 13 This is a schematic diagram illustrating the preparation of a cholesterol liquid crystal layer according to an embodiment of the present invention.

[0109] like Figure 13 As shown, during the preparation of the cholesterol liquid crystal layer, by controlling the hole depth in different areas of the imprint plate 800, the holes corresponding to the edge of the cholesterol liquid crystal layer 102 have a smaller depth, which can gradually reduce the thickness of the cholesterol liquid crystal layer 102 at the edge, thereby improving or eliminating the pattern contour problem caused by the edge step difference of the cholesterol liquid crystal layer 102 in the transparent mode.

[0110] like Figure 12 as well as Figure 13 As shown, the cholesteric liquid crystal layer 102 of this embodiment includes a plurality of cholesteric liquid crystal molecules 1021, and each cholesteric liquid crystal molecule 1021 is formed in a helical structure and has a helical axis CA, each helical axis CA being non-parallel to the normal of the cholesteric liquid crystal layer 102. In some embodiments, the angle between each helical axis CA and the normal of the cholesteric liquid crystal layer 102 is within the range of ±45 degrees. In some preferred embodiments, the angle between each helical axis CA and the normal of the cholesteric liquid crystal layer 102 is within the range of ±30 degrees. In some even preferred embodiments, the angle between each helical axis CA and the normal of the cholesteric liquid crystal layer 102 is within the range of ±10 degrees. By tilting each helical axis CA relative to the normal of the cholesteric liquid crystal layer 102, the blue shift problem of the cholesteric liquid crystal layer 102 at large viewing angles can be improved.

[0111] In summary, the electro-optical screen provided in this embodiment of the invention includes an electro-optical scattering element and an electro-optical decorative module for switching between different optical modes. More specifically, the switchable scattering element can switch between a scattering state and a transparent state, and is used in conjunction with an electro-optical waveplate in the electro-optical decorative module to generate multiple optical modes. The various optical modes of the electro-optical screen provide users with different visual experiences. When the electro-optical screen is configured in projection mode, it can effectively improve the visible brightness and contrast.

[0112] The above description is merely a preferred embodiment of the present invention and should not be construed as limiting the scope of the invention. Any simple equivalent changes and modifications made in accordance with the claims and description of the invention are still within the scope of this patent. Furthermore, no embodiment or claim of the present invention needs to achieve all the objectives, advantages, or features disclosed in the invention. In addition, the abstract and title (invention title) are only used to assist in patent document retrieval and are not intended to limit the scope of the invention. Furthermore, the terms "first," "second," etc., mentioned in this specification or claims are only used to name elements or distinguish different embodiments or scopes, and are not used to limit the upper or lower limit of the number of elements.

Claims

1. An electro-optical screen, characterized in that, The electro-optical screen includes a switchable scattering element and an electro-optical decorative module for switching between different optical modes, wherein: The switchable scattering element is disposed on one side of the electronically controlled decorative module to switch between a scattering state and a transparent state. The electronically controlled decorative module includes a first polarizing layer, a first quarter-wave plate, a cholesteric liquid crystal layer, an electronically controlled wave plate, a second quarter-wave plate, and a second polarizing layer, which are sequentially stacked. The electrically controlled waveplate includes a liquid crystal layer, and the second polarizing layer is disposed between the switchable scattering element and the second quarter-waveplate. The cholesteric liquid crystal layer is used to reflect either left-handed or right-handed circularly polarized light. The light absorption axis of the first polarizing layer is perpendicular to the light absorption axis of the second polarizing layer, and the optical axis of the first quarter-waveplate is parallel to the optical axis of the second quarter-waveplate; alternatively, the light absorption axis of the first polarizing layer is parallel to the light absorption axis of the second polarizing layer, and the optical axis of the first quarter-waveplate is perpendicular to the optical axis of the second quarter-waveplate. The electronically controlled decorative module further includes a compensation film disposed between the first quarter-wave plate and the second quarter-wave plate to compensate for the out-of-plane phase difference of the cholesterol liquid crystal layer.

2. The electro-optical screen according to claim 1, characterized in that, The switchable scattering element includes a liquid crystal layer.

3. The electro-optical screen according to claim 1, characterized in that, The electrically controlled waveplate is one of the following: a vertical alignment mode liquid crystal cell, an ECB mode liquid crystal cell, or an IPS mode liquid crystal cell.

4. The electro-optical screen according to claim 1, characterized in that, When the electro-optical screen switches to projection mode, the switchable scattering element is configured in the scattering state and the electro-optical waveplate is configured as a half-waveplate.

5. The electro-optical screen according to claim 4, characterized in that, When the electro-optical screen is in the projection mode, the electro-optical screen receives image light, and the switchable scattering element is used to scatter the image light.

6. The electro-optical screen according to claim 4, characterized in that, It also includes a Fresnel lens layer, the switchable scattering element being located between the electronically controlled decorative module and the Fresnel lens layer, the Fresnel lens layer including a semi-transparent semi-reflective layer, wherein the semi-transparent semi-reflective layer is disposed on at least a portion of the surface of the Fresnel lens layer away from the switchable scattering element.

7. The electro-optical screen according to claim 4, characterized in that, It also includes a prism layer, wherein the switchable scattering element is located between the electronically controlled decorative module and the prism layer, the prism layer including a reflective layer disposed on at least a portion of the surface of the prism layer away from the switchable scattering element.

8. The electro-optical screen according to claim 1, characterized in that, When the electro-optical screen is switched to decorative mode, the switchable scattering element is configured to the transparent state, and the electro-optical waveplate is configured as a half-waveplate.

9. The electro-optical screen according to claim 1, characterized in that, When the electro-optical screen is switched to transparent mode, the switchable scattering element is configured in the transparent state, and the electro-optical waveplate is configured to have no phase delay function.

10. The electro-optical screen according to claim 1, characterized in that, When the electro-optical screen switches to the light-collecting mode, the switchable scattering element is configured in the scattering state and the electro-optical waveplate is configured to have no phase delay function.

11. The electro-optical screen according to claim 1, characterized in that, The electronically controlled decorative module further includes a reflective polarizing layer and an O-plate optical compensation film, wherein the reflective polarizing layer is disposed between the second quarter-wave plate and the second polarizing layer, and the O-plate optical compensation film is disposed between the second polarizing layer and the reflective polarizing layer.

12. The electro-optical screen according to claim 11, characterized in that, The reflection axis of the reflective polarizing layer is parallel to the light absorption axis of the second polarizing layer.

13. The electro-optical screen according to claim 1, characterized in that, The sum of the out-of-plane phase difference of the compensation film, the out-of-plane phase difference of the cholesterol liquid crystal layer, the out-of-plane phase difference of the first quarter-wave plate, and the out-of-plane phase difference of the second quarter-wave plate is less than 100 nm.

14. The electro-optical screen according to claim 1, characterized in that, The cholesterol liquid crystal layer has a decorative pattern, and the pattern of the compensation film is the same as the decorative pattern of the cholesterol liquid crystal layer.

15. The electro-optical screen according to claim 14, characterized in that, The first quarter-wave plate and the second quarter-wave plate have the same pattern as the decorative pattern of the cholesterol liquid crystal layer.

16. The electro-optical screen according to claim 1, characterized in that, The thickness of the cholesterol liquid crystal layer gradually decreases at the edges.

17. The electro-optical screen according to claim 1, characterized in that, The cholesterol liquid crystal layer comprises a plurality of cholesterol liquid crystal molecules, and the plurality of cholesterol liquid crystal molecules form a plurality of helical structures, each of the plurality of helical structures having a helical axis, and each of the plurality of helical axes being non-parallel to the normal of the cholesterol liquid crystal layer.

18. The electro-optical screen according to claim 17, characterized in that, The angle between the helical axis of each of the plurality of helical structures and the normal of the cholesterol liquid crystal layer is within the range of ±45 degrees.

19. An electro-optical screen, characterized in that, The electro-optical screen includes a scattering element and an electro-optical decorative module for switching between different optical modes, wherein: The scattering element is disposed on one side of the electronically controlled decorative module, and The electronically controlled decorative module includes a first polarizing layer, a first quarter-wave plate, a cholesteric liquid crystal layer, an electronically controlled wave plate, a second quarter-wave plate, and a second polarizing layer, which are sequentially stacked. The first polarizing layer is disposed between the scattering element and the first quarter-wave plate. The cholesteric liquid crystal layer is used to reflect either left-handed or right-handed circularly polarized light. The light absorption axis of the first polarizing layer is perpendicular to the light absorption axis of the second polarizing layer, and the optical axis of the first quarter-wave plate is parallel to the optical axis of the second quarter-wave plate. Alternatively, the light absorption axis of the first polarizing layer is parallel to the light absorption axis of the second polarizing layer, and the optical axis of the first quarter-wave plate is perpendicular to the optical axis of the second quarter-wave plate. The electronically controlled decorative module further includes a compensation film disposed between the first quarter-wave plate and the second quarter-wave plate to compensate for the out-of-plane phase difference of the cholesterol liquid crystal layer.

20. The electro-optical screen according to claim 19, characterized in that, The electrically controlled waveplate is one of the following: a vertical alignment mode liquid crystal cell, an ECB mode liquid crystal cell, or an IPS mode liquid crystal cell.

21. The electro-optical screen according to claim 19, characterized in that, When the electro-optical screen switches to projection mode, the electro-optical waveplate is configured to have no phase delay function.

22. The electro-optical screen according to claim 21, characterized in that, When the electro-optical screen is in the projection mode, the electro-optical screen receives image light, and the image light sequentially passes through the second polarizing layer, the second quarter-wave plate, the electro-optical wave plate, the cholesteric liquid crystal layer, the first quarter-wave plate, and the first polarizing layer before being scattered by the scattering element.

23. The electro-optical screen according to claim 19, characterized in that, When the electro-optical screen is switched to decorative mode, the electro-optical waveplate is configured as a half-waveplate.

24. The electro-optical screen according to claim 19, characterized in that, The sum of the out-of-plane phase difference of the compensation film, the out-of-plane phase difference of the cholesterol liquid crystal layer, the out-of-plane phase difference of the first quarter-wave plate, and the out-of-plane phase difference of the second quarter-wave plate is less than 100 nm.

25. The electro-optical screen according to claim 19, characterized in that, The cholesterol liquid crystal layer has a decorative pattern, and the pattern of the compensation film is the same as the decorative pattern of the cholesterol liquid crystal layer.

26. The electro-optical screen according to claim 25, characterized in that, The first quarter-wave plate and the second quarter-wave plate have the same pattern as the decorative pattern of the cholesterol liquid crystal layer.

27. The electro-optical screen according to claim 19, characterized in that, The thickness of the cholesterol liquid crystal layer gradually decreases at the edges.

28. The electro-optical screen according to claim 19, characterized in that, The cholesterol liquid crystal layer comprises a plurality of cholesterol liquid crystal molecules, and the plurality of cholesterol liquid crystal molecules form a plurality of helical structures, each of the plurality of helical structures having a helical axis, and each of the plurality of helical axes being non-parallel to the normal of the cholesterol liquid crystal layer.

29. The electro-optical screen according to claim 28, characterized in that, The angle between the helical axis of each of the plurality of helical structures and the normal of the cholesterol liquid crystal layer is within the range of ±45 degrees.

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