A projection screen and projection system

Abstract

The application discloses a projection screen and a projection system. The projection screen comprises a phase disturbance layer and a reflection structure layer. The reflection structure layer comprises a Fresnel lens layer and a reflection layer covering the Fresnel lens layer. The interference of ambient light on a projection image can be inhibited by designing the angle of each lens unit of the Fresnel lens layer, and better light resistance is achieved. Traditional solutions only focus on the coherence of light in the time dimension and the space dimension, while the phase disturbance layer in the application can destroy the polarization consistency of the projection light, and non-uniformly disturb the phase, thereby effectively inhibiting speckle noise caused by polarization superposition phase interference, and improving the definition and visual comfort of a displayed image.

Description

Technical Field

[0001] This application relates to the field of projection technology, and more particularly to a projection screen and projection system. Background Technology

[0002] In recent years, with the development of laser display technology, ultra-short-throw projection systems have gained widespread attention in home theaters and commercial displays due to their compact structure, convenient installation, and high brightness. Unlike traditional mercury lamp light sources or light-emitting diode (LED) light sources, laser light sources offer high brightness and wide color gamut coverage, making the images richer, more natural, and more layered when applied to projection systems.

[0003] However, due to the high spatiotemporal coherence and narrow-band spectrum characteristics of laser light sources, speckle noise is generated on the projection screen, which will seriously affect the quality of the displayed image. Speckle noise comes from the superposition of interference in the following three dimensions: (1) Time dimension: longitudinal interference caused by the time coherence of light waves; (2) Spatial dimension: transverse phase difference interference caused by surface microstructure; (3) Polarization dimension: light intensity vector interference formed by the superposition of polarization states.

[0004] Traditional speckle suppression techniques primarily reduce the temporal coherence of the laser source by introducing dynamic structures such as rotating diffusers or vibrating waveplates within the projection equipment, thereby diffusing the interference pattern. However, these methods typically suffer from problems such as complex structures, large equipment size, high energy consumption, and mechanical wear. Utility Model Content

[0005] This application provides a projection screen and projection system that transfers the speckle suppression mechanism from the projection device end to the screen end, thereby enabling the projection screen to directly reduce speckle contrast.

[0006] A first aspect of this application provides a projection screen, comprising:

[0007] The reflective structure layer includes:

[0008] A Fresnel lens layer; the Fresnel lens layer includes multiple lens units, each lens unit including a lens surface and a non-lens surface; the lens surface is inclined relative to the plane of the projection screen; and

[0009] A reflective layer, at least located on the lens surface of the plurality of lens units; the tilt angle of the lens surface of each lens unit is configured such that the reflective layer on its surface receives the projected light emitted from the projection device and reflects it toward the viewer; and

[0010] A phase perturbation layer is located on the side of the reflective structure layer facing the viewer; the phase perturbation layer is used to disrupt the polarization uniformity of the incident light, generating a non-uniform perturbation in the phase of the incident light.

[0011] In some embodiments of this application, the phase perturbation layer includes:

[0012] A waveplate array comprising multiple waveplate units arranged in an array, wherein the optical axis direction of each waveplate unit is non-periodic.

[0013] In some embodiments of this application, the phase perturbation layer further includes:

[0014] A microstructure perturbation layer is located between the waveplate array and the reflective structure layer; the microstructure perturbation layer includes multiple microstructures for causing minute changes in the angle of the incident light.

[0015] A transparent substrate is located on the side of the waveplate array opposite to the microstructure perturbation layer.

[0016] In some embodiments of this application, the microstructure in the microstructure disturbance layer is a micropillar, microsphere, serrated structure or honeycomb structure.

[0017] In some embodiments of this application, the phase perturbation layer includes:

[0018] Substrate;

[0019] Multiple micro / nano structures are distributed on the substrate, the size of which is less than half the wavelength of the projected light; the orientation of the multiple micro / nano structures is non-periodic.

[0020] The substrate and multiple micro / nano structures located on the substrate constitute a metasurface.

[0021] In some embodiments of this application, the projection screen further includes:

[0022] A diffusion layer is located on the side of the phase perturbation layer opposite to the reflective structure layer; the diffusion layer includes:

[0023] The substrate is located on the side of the phase disturbance layer opposite to the reflective structure layer;

[0024] A diffusion structure is located on the surface of the substrate facing away from the phase disturbance layer.

[0025] In some embodiments of this application, the projection screen further includes:

[0026] An adhesive layer is used to bond the diffusion layer, the phase disturbance layer, and the reflective structure layer together.

[0027] In some embodiments of this application, the difference in refraction between two adjacent film layers in the projection screen is less than 0.1.

[0028] In some embodiments of this application, the reflective structure layer further includes:

[0029] A transflective layer, located on the side of the reflective layer facing the viewer; and

[0030] A light-transmitting medium layer is located between the transmissive and reflective layers and the reflective layer;

[0031] The transflective layer, the light-transmitting medium layer, and the reflective layer constitute a resonant structure; the product of the refractive index and the thickness of the light-transmitting medium layer satisfies the condition for the projection light emitted from the projection device to resonate.

[0032] A second aspect of this application provides a projection system, including:

[0033] Projection equipment, used to emit projection light; and

[0034] A projection screen is located on the light-emitting side of the projection device, and the projection screen is any of the projection screens described above.

[0035] The projection device is an ultra-short-throw laser projection device; the projection device includes:

[0036] A three-color laser source device for emitting three primary color lasers;

[0037] A display element, located on the light-emitting side of the three-color laser source device, is used to modulate the emitted laser light from the three-color laser source device to form a display image; and

[0038] The lens is located on the light-emitting side of the display element and projects the emitted light from the display element into an image.

[0039] The projection screen and projection system provided in this application include a phase disturbance layer and a reflective structure layer. The reflective structure layer includes a Fresnel lens layer and a reflective layer covering the Fresnel lens layer. By designing the angles of each lens unit in the Fresnel lens layer, interference from ambient light on the projected image can be suppressed, achieving better anti-light performance. The phase disturbance layer can disrupt the polarization consistency of the projected light, generating non-uniform disturbances in its phase. Compared to traditional solutions that only focus on the coherence of light in the time and spatial dimensions, the phase disturbance layer in this application can also disrupt the polarization consistency of the projected light in the polarization dimension, thereby effectively suppressing speckle noise caused by polarization superposition phase interference and improving the clarity and visual comfort of the displayed image. Attached Figure Description

[0040] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a schematic diagram of the projection system architecture;

[0042] Figure 2 This is one of the schematic diagrams of the cross-sectional structure of a projection screen;

[0043] Figure 3 This is a schematic diagram of the planar structure of the Fresnel lens layer;

[0044] Figure 4 This is a schematic diagram of the planar structure of a waveplate array;

[0045] Figure 5 A schematic diagram of the cross-sectional structure for phase perturbation;

[0046] Figure 6 This is a schematic diagram of the overall structure of the phase perturbation layer;

[0047] Figure 7 This is a schematic diagram of the micro / nano structure;

[0048] Figure 8 This is the second schematic diagram of the cross-sectional structure of the projection screen;

[0049] Figure 9 This is one of the schematic diagrams of a diffusion structure;

[0050] Figure 10 This is the second schematic diagram of a diffusion structure;

[0051] Figure 11 This is a schematic diagram of the cross-sectional structure of the resonant structure;

[0052] Figure 12 This is a schematic diagram of the projection device. Detailed Implementation

[0053] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the application will be further described below in conjunction with the accompanying drawings and embodiments. However, the exemplary embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided to make the application more comprehensive and complete, and to fully convey the concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the figures denote the same or similar structures, and therefore repeated descriptions of them will be omitted. Terms describing position and direction described in this application are illustrative based on the accompanying drawings, but changes can be made as needed, and all such changes are included within the scope of protection of this application. The accompanying drawings of this application are for illustrating relative positional relationships only and do not represent actual scale.

[0054] With the popularization of laser display products, the market for laser TVs, as a large-screen product to replace LCD TVs and OLED TVs, is rapidly expanding.

[0055] Laser TVs are essentially ultra-short-throw projection systems that use laser light sources. Ultra-short-throw projection systems have gained widespread attention in home theaters and commercial displays due to their compact structure, easy installation, and high brightness. Unlike traditional mercury lamp or light-emitting diode (LED) light sources, laser light sources offer high brightness and wide color gamut coverage. When applied to projection systems, they can make the image colors richer, more natural, and more layered, making them an ideal light source for projection systems.

[0056] However, due to the high spatiotemporal coherence and narrow-band spectrum characteristics of laser light sources, their high spatial coherence can easily generate laser speckle noise when interacting with the screen surface, resulting in grainy images, reduced detail resolution, and severely degraded viewing experience.

[0057] Speckle intensity is usually quantitatively evaluated using the physical quantity of "speckle contrast," which is defined as follows:

[0058]

[0059] Where, σ I This represents the standard deviation of light intensity in a local area of ​​an image. This represents the average light intensity. Higher speckle contrast indicates significant intensity inhomogeneity and graininess in the image, affecting display uniformity.

[0060] The speckle noise generated by the laser on the projection screen originates from the superposition of interference in three dimensions:

[0061] 1. Time dimension: Longitudinal interference caused by the temporal coherence of light waves;

[0062] 2. Spatial dimension: Lateral phase difference interference caused by the microstructure of the rough surface;

[0063] 3. Polarization dimension: Light intensity vector interference formed by the superposition of polarization states.

[0064] Current mainstream technologies primarily suppress speckle through projection techniques, such as disrupting the temporal coherence of the laser by using moving scattering elements like rotating diffusers or vibrating phase plates, thereby diffusing the interference pattern. While these methods are effective to some extent, they also introduce problems such as complex structures, increased power consumption, larger device size, and low integration.

[0065] To achieve better brightness and display effects, projection devices are generally used in conjunction with projection screens. This application provides a projection screen and projection system that, by transferring the speckle suppression mechanism from the projection device end to the screen end, allows the projection screen to directly reduce speckle contrast.

[0066] Specifically, such as Figure 1 As shown, the projection system includes: a projection device 2 and a projection screen 1.

[0067] The projection screen 1 is located on the light-emitting side of the projection device 2, and the audience faces the projection screen 1. The projection device 2 emits projection light, which enters the projection screen 1, passes through the projection screen 1, and exits towards the audience, thus allowing the audience to view the projected image.

[0068] When the projection device 2 and the audience are located on the same side of the projection screen 1, this projection system is called a front projection system. When the projection device 2 and the audience are located on opposite sides of the projection screen 1, this projection system is called a rear projection system. In a front projection system, the projection device 2 emits projection light onto the projection screen 1, and the projection screen 1 reflects the projection light back to the audience, allowing the audience to view the projected image. In a rear projection system, the projection device 2 emits projection light onto the projection screen 1, and the projection light passes through the projection screen 1 and exits towards the audience, allowing the audience to view the projected image.

[0069] This application embodiment uses a front-projection ultra-short-throw projection system as an example to specifically describe the structure of the projection screen. The projection screen 1 can be mounted on a wall or suspended high up, or it can be integrated with the projection device into a single display device. In use, the projection device 2 can be located below the projection screen 1, projecting light from below the projection screen 1 at an angle upwards; or, the projection device 2 can be located above the projection screen 1, projecting light from above the projection screen 1 at an angle downwards. This application embodiment illustrates an example where the projection device 2 is positioned near the bottom side of the projection screen 1. Because the ultra-short-throw projection system has a small throw ratio, a larger projected image can be obtained while reducing the distance between the projection device 2 and the projection screen 1, making it very suitable for applications such as laser TVs.

[0070] like Figure 1 As shown, the projection screen 1 is typically rectangular in shape and has an axially symmetrical structure. During use, its bottom and top sides are usually parallel to the horizontal direction x, and its two side sides are parallel to the vertical direction y. The horizontal direction x and the vertical direction y are perpendicular to each other. Here, the horizontal direction x refers to the direction parallel to the horizontal plane, and the vertical direction y is the direction within the plane of the projection screen that is perpendicular to the horizontal direction x. The projection device 2 is usually positioned in the center of the projection screen, and the projection light emitted from the projection device onto the projection screen is also symmetrically distributed.

[0071] Figure 2 This is one of the cross-sectional structural diagrams of the projection screen provided in an embodiment of this application. For example... Figure 2 As shown, the projection screen includes a phase disturbance layer 11 and a reflective structure layer 12, with the phase disturbance layer 11 located on the side of the reflective structure layer 12 facing the viewer.

[0072] The reflective structure layer includes a Fresnel lens layer 121 and a reflective layer 122. Figure 3 A schematic diagram of the Fresnel lens layer, as shown below. Figure 2 and Figure 3 As shown, the Fresnel lens layer 121 includes multiple lens units 121a, which form a circular Fresnel structure. These lens units 121 can be arranged in concentric circles that expand sequentially along the radial direction. When the projection screen is applied to an ultra-short throw projection system, the center O of the concentric lens units is usually not located within the projection screen. When the projection device emits projection light from below the projection screen, the center O of each lens unit is located below the bottom side of the projection screen and on the extension line of the projection screen's axis of symmetry I-I'. Along the projection screen from bottom to top, the radius of the lens units gradually increases, and the projection screen does not contain complete circular lenses, but only partially arc-shaped lenses.

[0073] Each lens unit 121a in the Fresnel lens layer 121 includes a lens surface x1 and a non-lens surface x2. The lens surface x1 is tilted relative to the plane of the projection screen, and the non-lens surface x2 is used to connect to the lens surface x1. The non-lens surface x2 can be a plane or a curved surface. The tilt angle of the lens surface x1 is designed according to the incident direction of the projection light and the desired exit direction of the light. After the reflective layer 122 is covered on the lens surface x1 of each lens unit 121a, the reflective layer 122 has the same tilt angle as the lens surface x1, so that the projection light L can be reflected towards the viewer after it is incident on the reflective layer 121 on the surface of the lens unit.

[0074] The Fresnel lens layer 121 achieves selective control of the incident angle of light through the optical design of each lens unit, improves the ambient light suppression performance, and focuses the light to a specific observation direction, so that the projected light is effectively guided to the viewer's eye position, thereby improving the front brightness of the projection screen and suppressing the contrast reduction caused by ambient light from the side, thereby improving image clarity and brightness efficiency.

[0075] In some embodiments, the Fresnel lens layer 121 can be injection molded using a UV-curable resin (such as UV resin), and its thickness is approximately 10 μm to 100 μm. The Fresnel lens layer 121 can be designed not only as a typical concentric circular Fresnel structure, but also as a linear array, and the tilt angle can be optimized according to a predetermined projection angle.

[0076] The reflective layer 121 is located on the surface of each lens unit 121a of the Fresnel lens layer and performs optical reflection function. It is used to efficiently reflect the projection light emitted from the projection device so that the projection light can finally be emitted from the projection screen.

[0077] In some embodiments, the reflective layer 122 may be a metal thin film with high reflectivity (e.g., aluminum or silver), and its thickness is controlled in the range of 30nm to 200nm, so as to balance the high reflectivity of the laser with the transmission and blocking performance of the external ambient light.

[0078] like Figure 1As shown in the embodiment of this application, the projection screen also includes a phase perturbation layer 11. The projected light is laser light, which is linearly polarized. The phase perturbation layer can generate non-uniform perturbation on the phase of the incident light, thereby converting the incident linearly polarized projection laser into a non-uniform combination of polarization states (such as elliptically polarized light or circularly polarized light). This applies polarization dimension decoherence processing to the projection laser, destroying the polarization matching condition of multi-beam interference and simultaneously destroying the spatial interference phase correlation of the laser, thus reducing the speckle contrast. The phase perturbation layer and the Fresnel lens layer work together to generate differentiated reflection paths of polarization components at the reflection angle, expanding the spatial frequency range of the interference pattern.

[0079] This phase disturbance layer is a static structure integrated inside the projection screen, requiring no moving mechanical parts. It boasts superior characteristics such as low power consumption, high reliability, and ease of integration into projection systems, while avoiding the complexity of the projection device's main structure. Therefore, while maintaining high contrast and high gain, it significantly improves the image quality and viewing comfort, making it particularly suitable for high-resolution laser projection applications such as 4K / 8K, exhibiting extremely high adaptability.

[0080] In some embodiments, such as Figure 4 As shown, the phase perturbation layer may include: a waveplate array composed of waveplate units 111 arranged in an array, wherein the optical axis direction of each waveplate unit 111 is non-periodic.

[0081] The waveplate unit 111 can be a uniaxial birefringent crystal, whose optical axis is a special direction inside the crystal. When light propagates along this direction, birefringence does not occur. This direction is also called the optical axis direction of the waveplate. In the waveplate, light is decomposed into two orthogonal polarization components, namely the ordinary ray (o ray) and the extraordinary ray (e ray). The o ray and the e ray propagate at different speeds in the crystal, thus producing a phase difference.

[0082] In the embodiments of this application, the waveplate unit can be a λ / 4 waveplate or a λ / 2 waveplate, wherein a λ / 4 waveplate can generate a phase difference of π / 2, and a λ / 2 waveplate can generate a phase difference of π. In addition, any waveplate that is not an integer multiple is applicable, including but not limited to λ / 3 waveplates, λ / 5 waveplates, etc.

[0083] Each waveplate unit 111 in the waveplate array can use the same type of waveplate or different waveplates, and the optical axis direction of the waveplates is non-periodic. This can disrupt the polarization state of the laser, transforming the laser from a linear polarization state to a spatially varying elliptic or circular polarization state, thereby breaking polarization coherence and suppressing speckle formation.

[0084] like Figure 4As shown, the optical axis direction of each waveplate unit 111 in the waveplate array can be randomly distributed in multiple directions (such as 45°, 135°, 225°, 315°) in the plane, forming a two-dimensional polarization perturbation array. This randomness helps to achieve spatially non-periodic phase perturbation in a large-area screen, thereby effectively reducing interference speckle and improving the visual uniformity and viewing comfort of the projected image.

[0085] The waveplate array can be made of birefringent materials, such as polyester extended film, single-crystal quartz, or polyimide. The waveplate units can be micro-regions with a single-sided dimension of less than 100 μm. The optical axis directions of each waveplate unit 111 are arranged at angles of 0°, 45°, 90°, 135°, etc., and can be periodic or randomly distributed, without limitation.

[0086] Furthermore, such as Figure 5 As shown, the phase perturbation layer also includes a transparent substrate 112 and a microstructure perturbation layer 113.

[0087] The microstructure perturbation layer 113 can be disposed between the waveplate array and the reflective structure layer. The microstructure perturbation layer comprises multiple microstructures used to cause minute changes in the angle of the incident light. The microstructures can be regularly arranged micropillars, microspheres, serrated structures, or honeycomb structures, with a preferred size range of 1 μm to 30 μm. This microstructure further perturbs the laser's emission direction after the projected laser is reflected, thus disrupting spatial interference stability.

[0088] The transparent substrate 112 is located on the side of the waveplate array opposite to the microstructure perturbation layer 113, and is used to support the waveplate array and the microstructure perturbation layer. The transparent substrate 112 can be made of plastic materials with high transparency and good processability, such as PMMA, PC or TAC, and its thickness is preferably 50μm to 300μm.

[0089] The aforementioned film structure of the phase perturbation layer can be integrated into an integral structure through processes such as lamination, imprinting, or optical transparent adhesive bonding, with the overall thickness controlled within 100μm.

[0090] In some embodiments, such as Figure 6 and Figure 7 As shown, the phase perturbation layer includes a substrate 114 and a plurality of micro / nano structures 115 located on the substrate. The size of the micro / nano structures 115 is less than half the wavelength of the projected light, and the substrate 114 and the plurality of micro / nano structures 115 located on the substrate constitute a metasurface.

[0091] The phase perturbation layer can employ a subwavelength optical meta-optics phase layer to perturb the conditions for the formation of interference patterns in the beam, thereby effectively reducing the visibility of interference speckle.

[0092] The substrate 114 can be a transparent substrate such as glass, PMMA or PC, and the micro-nano structure 115 can be a material with the highest possible refractive index. A two-dimensional pattern array with subwavelength scale is formed on the substrate through micro-nano processes such as nanoimprinting, electron beam etching or dry etching.

[0093] The shape of the micro / nano structure 115 can be cylindrical, cross-shaped, H-shaped or strip-shaped, and it can be arranged periodically or non-periodically in space. By locally changing the arrangement orientation and symmetry axis direction of the micro / nano structure 115, the phase delay of the equivalent λ / 4 waveplate or λ / 2 waveplate can be achieved, thereby forming a polarization-phase modulation structure with artificial optical axis distribution.

[0094] In some embodiments, based on the Pancharatnam-Berry (PB) phase principle, spatially anisotropic directional phase perturbations can be applied to the incident polarized light in different regions of the metasurface to form complex polarization and phase field distributions. This effect can be regarded as a structural mechanism for breaking the interference stability in the laser beam path. Without changing the coherence of the light source itself, it destroys the formation conditions of interference fringes, which is equivalent to physical "decoherence", thereby effectively suppressing speckle caused by interference.

[0095] This subwavelength metasurface does not rely on natural birefringent materials, offers a high degree of design freedom, and is compatible with existing nanoimprinting or flexible substrate technologies. It is suitable for planar, curved, and rollable projection screens. The overall thickness can be controlled between 1μm and 5μm, offering advantages such as high precision and mass production capability.

[0096] The phase perturbation layers provided in the embodiments of this application are all static passive structures that can continuously provide stable speckle suppression effects without the need for electric drive, thermal response or mechanical movement.

[0097] In some embodiments, such as Figure 8 As shown, the projection screen may further include a diffusion layer 13, located on the side of the phase perturbation layer 11 away from the reflective structure layer 12. The diffusion layer 13 can diffuse the incident light, thereby further dispersing the coherent light at different angles, which helps to soften the image, improve the uniformity of the light field, and widen the effective viewing angle range. The diffusion layer 13 not only has the function of diffusing the projected image, but also has a certain degree of scattering and shielding effect on the external ambient light.

[0098] like Figure 8 As shown, the diffusion layer includes a substrate 131 and a diffusion structure 132 located on the surface of the substrate. The substrate 131 provides support for the entire structure and can be made of a resin material with high optical transparency (such as PET, PMMA, PC, etc.). The diffusion structure 132 is formed on the surface of the substrate facing away from the phase disturbance layer 11.

[0099] In some embodiments, the diffusion layer 13 may also have anisotropic diffusion functionality. Anisotropic diffusion refers to the different degrees of light diffusion in different directions. In this embodiment, the anisotropic diffusion layer diffuses light more effectively along the horizontal direction x than along the vertical direction y. Since viewers do not require a large viewing angle in the vertical direction when viewing a projection screen, but need a large viewing angle in the horizontal direction to expand the visible range, an anisotropic diffusion layer in the projection screen can diffuse the horizontal diffusion angle of light, thereby expanding the visible range of the projected image.

[0100] To achieve anisotropic diffusion characteristics, the diffusion structure can employ a linear lens structure, such as... Figure 9 As shown, the linear lens structure 132a can adopt a lenticular lens structure, or, as... Figure 10 As shown, the linear mirror structure 132a can adopt a prism structure (Prism). For example... Figure 9 and Figure 10 As shown, the axis of the linear lens structure 132a is parallel to the vertical direction y and arranged sequentially along the horizontal direction x.

[0101] Continue to refer to Figure 8 The projection screen also includes an adhesive layer 14, a diffusion layer 13, a phase disturbance layer 11, and a reflective structure layer 12, which are bonded together by the adhesive layer 14.

[0102] The adhesive layer 14 can be made of optically clear adhesive (OCA) or optically clear resin (OCR) to ensure that optical performance is not disturbed and to achieve stable interlayer bonding. The bonding material used in the adhesive layer 14 must have high light transmittance (transmittance ≥ 92%), isotropy, and refractive index matching between the layers. Refractive index matching between layers means that the difference in refractive index between adjacent layers is less than or equal to 0.1.

[0103] In specific implementation, such as Figure 8 As shown, the Fresnel lens layer can also be disposed on the substrate 123, and the adhesive layer is used to bond the substrate of the diffusion layer 13 and the reflective structure layer 12 to the phase disturbance layer 11.

[0104] The materials used in the projection screen should be chosen to keep the refractive difference between two adjacent layers less than 0.1, which can reduce Fresnel reflection loss caused by refractive index mismatch.

[0105] The projection light emitted by the projection device, after entering the projection screen, passes sequentially through the diffusion layer 13, the phase disturbance layer 11, and the Fresnel lens layer 121, finally reaching the reflection layer 122 where it is reflected. It then passes sequentially through the Fresnel lens layer 121, the phase disturbance layer 11, and the diffusion layer 13 before exiting the projection screen and continuing to propagate towards the viewer. The projection light emitted by the projection device is laser light. When the laser light passes through the phase disturbance layer 11, the phase disturbance layer 11, through its spatially distributed phase delay characteristics, locally modulates the propagation phase of the laser light. This breaks the polarization uniformity and coherence of the reflected beam, reduces the probability of interference speckle formation, and improves the uniformity and visual comfort of the projected image.

[0106] An ideal projection screen not only needs to meet basic performance requirements such as high gain, high contrast, and wide viewing angle, but should also possess the following characteristics:

[0107] 1. It has excellent anti-interference capabilities under strong ambient light;

[0108] 2. Designed for low dizziness and eye comfort, suitable for extended viewing;

[0109] 3. It has the ability to spectrally modulate the wavelength-selective reflection of the projected laser.

[0110] The projection screen provided in this application embodiment, by setting a Fresnel lens layer in the screen and designing the angle of each lens unit of the Fresnel lens layer, can suppress the interference of ambient light on the projected image, achieving better anti-light performance. Setting a phase perturbation layer in the projection screen can break the polarization uniformity and coherence of the laser beam, reduce the probability of interference speckle formation, and improve the uniformity and visual comfort of the projected image.

[0111] To further enhance image contrast and achieve wavelength-selective reflection of projected light and suppression of ambient light, the reflective layer 122 on the lens surface of the lens unit 121 can be replaced with a resonant structure F that has wavelength-selective reflection characteristics. The resonant structure utilizes the principle of resonant enhancement of light of a set wavelength to selectively enhance the reflection of the projected light emitted from the projection device, while absorbing light of other wavelengths. This makes the reflectivity of the reflective structure layer 12 for the projected light emitted from the projection device greater than its reflectivity for other wavelengths, thereby significantly improving the contrast of the projected image.

[0112] Specifically, such as Figure 11 As shown, the resonant structure F, in addition to the reflective layer 122, also includes a transflective layer 124 and a light-transmitting medium layer 125. The transflective layer 124, the light-transmitting medium layer 125, and the reflective layer 122 are sequentially formed on the lens surface of each lens unit.

[0113] The transflective layer 124 has a semi-transparent and semi-reflective property. It should be noted that the semi-transparent and semi-reflective property mentioned in this embodiment does not mean that the transmittance and reflectance of light are both 50%. Rather, it indicates that the transflective layer 124 can achieve the property of partially transmitting and partially reflecting light. Its transmittance and reflectance can be adjusted according to actual requirements, and the specific transmittance and reflectance of the transflective layer 124 are not limited here. The transflective layer 124 allows the projected light to enter the resonant structure when it is incident on the projection screen, and after the projected light oscillates and intensifies within the resonant structure, it can also exit through the transflective layer 124.

[0114] In practical implementation, the transmissive and reflective layer 124 can be a laminated structure formed by at least one metal or two or more metals selected from Al, Nb, Ag, and Ti. The thickness of the transmissive and reflective layer 124 can be controlled between 2 nm and 20 nm, so that the transmissive and reflective layer 124 has a certain degree of light transmittance and also has reflectivity.

[0115] The reflective layer 122 has the function of reflecting light. The reflective layer 122 is located on the side away from the audience and does not need to transmit light. Therefore, it can be made of a material with reflective properties but no light transmission properties.

[0116] In practical implementation, the reflective layer 122 can be made of materials such as Al, aluminum alloy, Ag, or silver alloy, and the thickness of the reflective layer 122 is greater than the thickness of the transmissive layer 124. The thickness of the reflective layer 122 needs to be greater than 50 nm to ensure that the reflective layer 122 has better reflection efficiency.

[0117] The light-transmitting dielectric layer 125 is located between the light-transmitting and reflective layers 124 and 122. The product of the thickness and refractive index of the light-transmitting dielectric layer 125 determines the cavity length of the resonant structure. Therefore, when designing the resonant structure, it is necessary to select a dielectric material whose product of refractive index and thickness satisfies the conditions for the projection light emitted from the projection device to generate resonance.

[0118] In practice, the light-transmitting medium layer 125 can be made of materials such as metal oxides, nitrides or transparent resins.

[0119] In this embodiment, the projection light source can be a three-color laser light source, which can emit red laser, green laser and blue laser. By adjusting the refractive index and optical thickness of the light-transmitting medium layer, the resonant cavity can simultaneously enhance the reflection of red laser, green laser and blue laser, while attenuating the reflection of other wavelengths of light, thereby improving the contrast of the projected light.

[0120] This application also provides a projection system, such as... Figure 1As shown, the projection system includes: a projection device 2 and a projection screen 1 located on the light-emitting side of the projection device 2.

[0121] Figure 12 This is a schematic diagram of the projection device provided in an embodiment of this application.

[0122] like Figure 12 As shown, the projection device includes: a projection light source 21, an illumination light path 22, a display element 23, and a lens 24. The illumination light path 22 is located on the light-emitting side of the projection light source 21, the display element 23 is located on the light-emitting side of the illumination light path 22, and the lens 24 is located on the light-emitting side of the display element 23.

[0123] The projection light source 21 can be a laser light source device. This laser light source device can be a monochromatic laser, a laser capable of emitting multiple colors of laser light, or multiple lasers emitting different colors of laser light. When a monochromatic laser is used, the laser display device also needs to include a color conversion device and a color wheel. The color conversion device performs color conversion, and the color wheel filters the emitted light. The monochromatic laser, in conjunction with the color conversion device and color wheel, can achieve the purpose of emitting different primary colors of light in a sequential manner. When a laser capable of emitting multiple colors of laser light is used, it is necessary to control the laser light source to emit different colors of laser light as primary colors in a sequential manner.

[0124] In this embodiment, the projection light source can be a three-color laser light source device. This device can be a laser that emits three primary colors of laser light, such as an MCL laser; or it can include a red laser, a green laser, and a blue laser that emit three primary colors of laser light respectively. Using a three-color laser light source device is beneficial for improving the color gamut of the projected image, resulting in better color performance and accurate reproduction of the input image.

[0125] The illumination path 22 is located on the light-emitting side of the projection light source 21. The illumination path 22 collimates and homogenizes the emitted light from the projection light source 21, and also allows the emitted light from the projection light source 21 to enter the display element 23 at a suitable angle. The illumination path 22 may include multiple lenses or lens groups, which are not limited here.

[0126] Display element 23 is used to modulate the incident light. In a specific implementation, display element 23 can be a digital micromirror device (DMD). After passing through illumination path 22, the light beam conforms to the illumination size and incident angle required by the DMD. The DMD surface includes a number of micromirrors, each of which can be individually driven to deflect. By controlling the deflection angle of the DMD, the brightness of the light incident on lens 24 is controlled.

[0127] Lens 24 is used to image the light emitted from display element 23 and to project the image onto projection screen 1.

[0128] In this embodiment, the projection device 2 can be a short-throw or ultra-short-throw projection device, that is, the lens 24 in the projection device is a short-throw or ultra-short-throw lens. Using a short-throw or ultra-short-throw projection device can greatly shorten the distance between the projection device 2 and the projection screen 1, while also enabling large-size image display.

[0129] The projection screen 1 is located on the light-emitting side of the lens in the projection device. The projection screen includes at least a phase disturbance layer and a reflective structure layer. The reflective structure layer includes a Fresnel lens layer and a reflective layer covering the Fresnel lens layer. By designing the angles of each lens unit in the Fresnel lens layer, interference from ambient light on the projected image can be suppressed, achieving better anti-light performance. Setting a phase disturbance layer in the projection screen can disrupt the polarization uniformity and coherence of the projected beam, reducing the probability of interference speckle formation and improving the uniformity and visual comfort of the projected image.

[0130] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0131] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A projection screen, characterized in that, include: The reflective structure layer includes: A Fresnel lens layer; the Fresnel lens layer includes multiple lens units, each lens unit including a lens surface and a non-lens surface; the lens surface is inclined relative to the plane of the projection screen; and A reflective layer, at least located on the lens surface of the plurality of lens units; the tilt angle of the lens surface of each lens unit is configured such that the reflective layer on its surface receives the projected light emitted from the projection device and reflects it toward the viewer; and A phase perturbation layer is located on the side of the reflective structure layer facing the viewer; the phase perturbation layer is used to disrupt the polarization uniformity of the incident light, generating a non-uniform perturbation in the phase of the incident light.

2. The projection screen as described in claim 1, characterized in that, The phase perturbation layer includes: A waveplate array comprising a plurality of waveplate units arranged in an array, wherein the optical axis direction of each waveplate unit is non-periodic.

3. The projection screen as described in claim 2, characterized in that, The phase perturbation layer also includes: A microstructure perturbation layer is located between the waveplate array and the reflective structure layer; the microstructure perturbation layer includes multiple microstructures for causing minute changes in the angle of the incident light. A transparent substrate is located on the side of the waveplate array opposite to the microstructure perturbation layer.

4. The projection screen as described in claim 3, characterized in that, The microstructures in the microstructure disturbance layer are micropillars, microspheres, sawtooth structures, or honeycomb structures.

5. The projection screen as described in claim 1, characterized in that, The phase perturbation layer includes: Substrate; Multiple micro / nano structures are distributed on the substrate, the size of which is less than half the wavelength of the projected light; the orientation of the multiple micro / nano structures is non-periodic. The substrate and the multiple micro / nano structures located on the substrate constitute a metasurface.

6. The projection screen as described in any one of claims 1 to 5, characterized in that, Also includes: A diffusion layer is located on the side of the phase disturbance layer opposite to the reflective structure layer; The diffusion layer includes: The substrate is located on the side of the phase disturbance layer opposite to the reflective structure layer; A diffusion structure is located on the surface of the substrate facing away from the phase disturbance layer.

7. The projection screen as described in claim 6, characterized in that, Also includes: An adhesive layer is used to bond the diffusion layer, the phase disturbance layer, and the reflective structure layer together.

8. The projection screen as described in claim 7, characterized in that, The difference in refraction between two adjacent film layers in the projection screen is less than or equal to 0.

1.

9. The projection screen as described in any one of claims 1 to 5, characterized in that, The reflective structure layer further includes: A transflective layer, located on the side of the reflective layer facing the viewer; and A light-transmitting medium layer is located between the transmissive and reflective layers and the reflective layer; The transflective layer, the light-transmitting medium layer, and the reflective layer constitute a resonant structure; the product of the refractive index and the thickness of the light-transmitting medium layer satisfies the condition for the projection light emitted from the projection device to resonate.

10. A projection system, characterized in that, include: Projection equipment, used to emit projection light; and A projection screen is located on the light-emitting side of the projection device, and the projection screen is the projection screen according to any one of claims 1 to 9; The projection device is an ultra-short-throw laser projection device; the projection device includes: A three-color laser source device for emitting three primary color lasers; A display element, located on the light-emitting side of the three-color laser source device, is used to modulate the emitted laser light from the three-color laser source device to form a display image; and The lens is located on the light-emitting side of the display element and projects the emitted light from the display element into an image.

Images