Projection screen and projection system

Abstract

A projection screen and a projection system. The projection screen comprises a surface layer (11) and a reflective structure layer (12). The reflective structure layer (12) comprises a substrate (122), a plurality of support structures (f), and a reflective layer (121). The reflective layer (121) located on inclined surfaces of the support structures (f) forms a plurality of micro-reflective surfaces arranged in an array. The micro-reflective surfaces are used for receiving projection light emitted by a projection device and reflecting the projection light toward the direction of a viewer, so that each position of the projection screen has relatively high gain. The micro-reflective surfaces are grouped so that pixels of an image projected onto the projection screen cover a plurality of reflective groups. In a same reflective group, the phases of the projection light reflected by the micro-reflective surfaces are identical. Thus, reflected light from different micro-reflective surfaces in the same reflective group can be approximated as a plane wave. All the micro-reflective surfaces in the same reflective group can be regarded as an overall reflective surface, thereby reducing the influence caused by diffraction and improving the control of angles by the micro-reflective surfaces.

Description

A projection screen and projection system

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese Patent Application No. 202510121143.6, filed on January 24, 2025, entitled “A Projection Screen and Projection System”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application relates to the field of projection technology, and in particular to a projection screen and projection system. Background Technology

[0004] As display products continue to trend towards larger sizes, considering factors such as power consumption, weight, and size, the market for projection displays as large-screen alternatives to LCD and OLED televisions is rapidly expanding. Current front-projection systems work in conjunction with a projection screen. The projector emits projection light, which is then incident on the projection screen, reflected, and finally seen by the viewer's eyes to produce the projected image.

[0005] Current projection screens can employ various structures to achieve different effects. One type of screen uses a reflective material coated on the substrate surface to reflect projected light. This type of screen is inexpensive, but it is difficult to achieve high gain.

[0006] Another type of screen incorporates a Fresnel lens, with a reflective layer formed on the lens surface. This type of screen can improve gain, but due to the aberrations inherent in the Fresnel lens, it is difficult to optimize its design.

[0007] Another type of screen incorporates multiple micro-reflective surfaces. The tilt direction and angle of these micro-reflective surfaces are precisely designed based on the location of the projected light incident on the screen, allowing for higher gain across the entire screen. However, due to limitations in manufacturing processes, the micro-reflective surfaces are relatively small and susceptible to light diffraction, sometimes preventing the screen from achieving the desired characteristics. Summary of the Invention

[0008] This application provides a projection screen, including:

[0009] Surface layer; and

[0010] A reflective structural layer is located on the side of the surface layer away from the viewer; the reflective structural layer includes:

[0011] Substrate;

[0012] Multiple support structures are located on the surface of the substrate; the surface of each support structure away from the substrate is inclined relative to the plane of the substrate; and

[0013] A reflective layer is applied to the inclined surface of the supporting structure, forming multiple micro-reflective surfaces; these multiple micro-reflective surfaces are arranged in an array; these multiple micro-reflective surfaces are used to receive the projected light emitted from the projection device and reflect it towards the viewer;

[0014] The plurality of micro-reflective surfaces are divided into a plurality of reflection groups. The pixels of the image projected onto the projection screen by the projected light cover a plurality of the reflection groups. The projected light reflected by adjacent micro-reflective surfaces within the same reflection group has the same phase.

[0015] Furthermore, embodiments of this application also provide a projection system, including:

[0016] Projection equipment, used to emit projection light; and

[0017] A projection screen, located on the light-emitting side of the projection device, wherein the projection screen is any of the aforementioned projection screens;

[0018] The projection device is an ultra-short-throw laser projection device; the projection device includes:

[0019] A three-color laser source device for emitting three primary color lasers;

[0020] 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

[0021] 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. Attached Figure Description

[0022] Figure 1 is a schematic diagram of the projection system provided in an embodiment of this application;

[0023] Figure 2 is a plan view of the projection screen provided in an embodiment of this application;

[0024] Figure 3 is a schematic diagram of a projection screen used in conjunction with a front projection system;

[0025] Figure 4 is a schematic diagram of another type of projection screen used in conjunction with a front projection system.

[0026] Figure 5 is a planar schematic diagram of the support structure in the projection screen shown in Figure 4;

[0027] Figure 6 is one of the structural schematic diagrams of the projection screen provided in the embodiment of this application;

[0028] Figure 7 is a planar schematic diagram of the support structure in the projection screen shown in Figure 6;

[0029] Figure 8 is a partial enlarged view of the support structure;

[0030] Figure 9 is one of the wavefront schematic diagrams provided in the embodiments of this application;

[0031] Figure 10 is a second schematic diagram of the wave surface provided in an embodiment of this application;

[0032] Figure 11 is a third schematic diagram of the wave surface provided in the embodiment of this application;

[0033] Figure 12 is a second schematic diagram of the structure of the projection screen provided in the embodiment of this application;

[0034] Figure 13 is one of the structural schematic diagrams of the surface layer provided in the embodiments of this application;

[0035] Figure 14 is a second schematic diagram of the surface layer structure provided in an embodiment of this application;

[0036] Figure 15 is a schematic diagram of the projection device provided in an embodiment of this application. Detailed Implementation

[0037] 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.

[0038] With the increasing popularity of laser display products, the market for laser TVs, as a large-screen alternative to LCD and OLED TVs, is rapidly expanding. To achieve better brightness and display effects, projection equipment is typically used in conjunction with a projection screen.

[0039] As shown in Figure 1, the projection system includes: projection device 2 and projection screen 1.

[0040] 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.

[0041] 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.

[0042] This application embodiment uses an 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 on the side near the bottom 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.

[0043] As shown in Figures 1 and 2, the projection screen 1 is typically rectangular in shape and has an axially symmetrical structure with the axis of symmetry being I-I'. In 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 on the horizontal plane, and the vertical direction y is the direction perpendicular to the horizontal direction x within the plane of the projection screen. 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.

[0044] Figure 3 shows a projection screen used in conjunction with a front-projection system. As shown in Figure 3, the projection screen includes a substrate 122 and a reflective layer 121 located on the surface of the substrate 122. This projection screen can be formed by coating the surface of the substrate 122 with a reflective material, resulting in low production costs. Projection light L enters the projection screen from one side of the reflective layer 121 and is reflected towards the viewer by the reflective layer 121. While certain characteristics can be achieved by selecting a reflective material to adjust the projection screen, achieving high gain is difficult, especially in short-throw or ultra-short-throw projections where contrast is typically low.

[0045] Figure 4 shows another projection screen used in conjunction with a front projection system. As shown in Figure 4, the projection screen includes a surface layer 11 and a reflective structure layer 12. The reflective structure layer 12 includes multiple support structures f, and the reflective layer 121 covers the surface of the support structures f. The support structure f refers to the structure that supports the reflective layer 121.

[0046] Figure 5 is a planar schematic diagram of the support structure in the projection screen shown in Figure 4. As shown in Figure 5, the support structure in this projection screen can adopt a Fresnel lens structure, which includes multiple lens units. These lens units can be seen as the support structure f acting on the supporting reflective layer 121. As shown in Figure 5, these lens units can form 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 inside 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.

[0047] Each lens unit in the Fresnel lens structure is tilted relative to the plane of the projection screen, and the tilt angle is set according to the incident direction of the projection light and the desired exit direction of the light. After the reflective layer 121 is covered on the surface of the Fresnel lens structure, the reflective layer 121 has the same tilt angle as the lens unit, so that after the projection light L is incident on the reflective layer 121 on the surface of the lens unit, it can be reflected in the direction of the viewer, thereby improving the gain of the projection screen.

[0048] However, because Fresnel lenses are axially symmetric, they are difficult to fully optimize across the entire screen due to aberrations and other factors.

[0049] Therefore, another support structure for the projection screen is proposed. Figure 6 is a schematic diagram of the projection screen provided in an embodiment of this application. As shown in Figure 6, the projection screen includes a surface layer 11 and a reflective structure layer 12. The reflective structure layer 12 is located on the side of the surface layer 11 away from the viewer.

[0050] The surface layer 11 can be located on the outermost surface of the projection screen. In some embodiments, the surface layer 11 is located on the side closest to the audience, which serves to protect the projection screen. In addition, the surface layer 11 can be processed in various ways according to different needs to achieve effects such as expanding the viewing angle, resisting ambient light reflection, and resisting ceiling reflection.

[0051] The reflective structure layer 12 includes a substrate 122 and a plurality of support structures f located on the surface of the substrate 122, the surface of the support structures f being covered by the reflective layer 121.

[0052] Figure 7 is a planar schematic diagram of the support structure in the projection screen shown in Figure 6. As shown in Figures 6 and 7, multiple support structures f are arranged in an array, with one side surface of each support structure in contact with the substrate 122. The side surface opposite to the substrate 122 is an inclined surface relative to the plane of the substrate 122. A reflective layer 121 covers the inclined surface of the support structure f to form a micro-reflective surface. The tilt angle of the micro-reflective surface is set to receive the projection light emitted from the projection device and reflect it towards the viewer. This allows for setting an optimal tilt direction and tilt angle for each position on the projection screen, enabling high gain across the entire screen.

[0053] As shown in Figure 7, the inclined surface of the support structure can be set as a rectangle, correspondingly making the micro-reflective surface rectangular. Since the projection light emitted from the projection device onto the projection screen is symmetrically distributed, the tilt direction and tilt angle of all support structures f and their surface reflective layers are symmetrically distributed with respect to the axis of symmetry I-I'. Their tilt direction needs to be set according to the direction of the incident projection light and the direction of reflection towards the viewer.

[0054] Figure 8 is a partially enlarged view of the support structure. As shown in Figure 8, the angle between the inclined surface of the support structure f and the surface of the substrate along the horizontal direction x is the first angle α, and the angle between the inclined surface of the support structure f and the surface of the substrate along the vertical direction y is the second angle β. Both the first angle α and the second angle β need to be set according to the incident direction and incident angle of the incident projection light, so that the projection light incident on the micro-reflective surface can be reflected in the direction of the audience, thereby improving the gain of the projection screen.

[0055] Referring to Figure 8, the pitch of the support structure along the horizontal direction x is Ph, and the pitch along the vertical direction y is Pv. The pitch of the inclined surface of the support structure along the horizontal direction x is Ph, and the first included angle α along the horizontal direction x determines its cross-sectional height h1 along the horizontal direction. The pitch of the inclined surface of the support structure along the vertical direction y is Pv, and the second included angle β along the vertical direction y determines its cross-sectional height h2 along the vertical direction y.

[0056] Typically, in a projection screen's cross-section along the horizontal x-axis or vertical y-axis, the supporting structure's cross-sectional shape is triangular, and these triangles are arranged continuously. The apex side of each triangle corresponds to the side of the inclined surface of the supporting structure in the cross-sectional shape.

[0057] The support structure f in the reflective structure layer 12 can be 3D printed on the surface of the substrate 122. Specifically, the support structure is first 3D modeled according to the distribution of projected light to obtain 3D data. This 3D data is then imported into slicing software for calculation, decomposing the 3D data into layered 2D planar data. The 3D printer then prints layer by layer based on the received 2D planar data to construct the three-dimensional structure.

[0058] As the 3D printing process shows, as the height of the support structure increases, the number of 3D printing layers increases proportionally, leading to higher costs and longer processing time. Therefore, the size of the support structure f should not be too large, typically on the order of micrometers. Correspondingly, the size of the micro-reflective surface is also typically on the order of micrometers.

[0059] When the size of the micro-reflective surface is reduced to a fraction of the wavelength of the incident projected light, the diffraction effect becomes non-negligible. Diffraction refers to the phenomenon where light waves propagate around obstacles, slits, or small holes. Due to the diffraction effect, the micro-reflective surface's ability to control the reflection of incident projected light has a diffraction limit.

[0060] For example, if the micro-reflective surface is a square with a side length of 10 μm, then due to the diffraction effect, the smallest resolvable angle is: Δθ≈λ / D;

[0061] Where λ represents the wavelength of the incident light, and D represents the side length of the micro-reflective surface. It is worth noting that the above formula is usually used to calculate the diffraction limit of a circle with an aperture of D. In this embodiment, D represents the side length of a square and is only used for rough estimation.

[0062] Assuming the incident light wavelength is 550 nm, the smallest resolvable angle due to diffraction is 0.055 rad, approximately 3.2 degrees. Theoretically, it's impossible to achieve an angle smaller than 3.2 degrees using a micro-reflective surface with a side length of 10 μm. Furthermore, according to the above formula, as the size of the micro-reflective surface decreases, the adjustable angle increases further. This results in less reflected light in the desired direction using the micro-reflector, while the light will be emitted in unwanted directions, leading to a larger viewing angle on the screen.

[0063] To overcome the problems caused by the diffraction limit, the embodiments of this application divide the micro-reflective surface into multiple reflection groups. The pixels of the image projected onto the projection screen will cover multiple reflection groups, and the phase of the projected light reflected by adjacent micro-reflective surfaces within the same reflection group will be the same.

[0064] According to the Huygens-Fresnel principle, diffraction can be considered as the result of the superposition of multiple secondary waves with different phases. If the micro-reflecting surfaces within the same reflection group are adjusted so that the reflected light after the incident projection light is reflected has the same phase, then the reflected light from different micro-reflecting surfaces can be approximated as a plane wave, thereby significantly reducing the influence of diffraction.

[0065] Specifically, the projection device is equipped with a display element, which includes multiple pixels. The light emitted from each pixel passes through the lens and is imaged on the projection screen to form a light spot, which is the pixel of the aforementioned image. This light spot will cover one or more reflective groups.

[0066] The light emitted from a pixel of the display element strikes the projection screen at approximately the same direction and angle, and the projection screen reflects the light from that pixel in the same direction. However, the pixel size of the image projected onto the screen is typically much larger than the size of the microreflective surface. For example, on a 100-inch 4K projection screen, the size of a single pixel is approximately 0.6 mm; while the minimum size of a microreflective surface manufactured using 3D printing technology is around 1 μm. Taking a square microreflective surface with a side length of 10 μm as an example, each pixel in the image corresponds to 60 × 60 microreflective surfaces.

[0067] These 60×60 micro-reflective surfaces can be divided into more than one reflection group. Within the same reflection group, the micro-reflective surfaces have the same tilt direction and tilt angle. However, different reflection groups control light in different directions and angles, therefore the tilt direction and / or tilt angle of the micro-reflective surfaces within different reflection groups are different. For example, two reflection groups symmetrically arranged with respect to the axis of symmetry I-I' of the projection screen have symmetrical tilt directions for the micro-reflective surfaces, but the same tilt angle.

[0068] Figure 9 illustrates the phase of incident and reflected light by showing an example of a cross-section in a defined direction where each reflective group contains three micro-reflective surfaces. The defined direction can be either the horizontal (x) or the vertical (y) direction. As shown in Figure 9, three support structures (f) are provided on the substrate 122. A reflective layer 121 is covered on the inclined surface of the support structure (f) to form micro-reflective surfaces. From left to right, the reflective group includes micro-reflective surface 1, micro-reflective surface 2, and micro-reflective surface 3, which are arranged closely together. Since the distance between the projection device and the projection screen is sufficiently large relative to the size of the micro-reflective surfaces, the incident light incident on this reflective group can be approximated as light rays incident from infinity onto the projection screen, and the incident light can be approximated as a plane wave.

[0069] Incident light simultaneously strikes micro-reflecting surfaces 1, 2, and 3. The light rays incident on the edges of the three micro-reflecting surfaces are represented as follows: incident rays 1A and 1B are incident rays incident on the two edges of micro-reflecting surface 1; incident rays 2A and 2B are incident rays incident on the two edges of micro-reflecting surface 2; and incident rays 3A and 3B are incident rays incident on the two edges of micro-reflecting surface 3. The incident rays 1A and 1B, after being reflected by micro-reflecting surface 1, are reflected rays 1A and 1B; the incident rays 2A and 2B, after being reflected by micro-reflecting surface 2, are reflected rays 2A and 2B; and the incident rays 3A and 3B, after being reflected by micro-reflecting surface 3, are reflected rays 3A and 3B.

[0070] Incident rays 1A and 1B have the same optical path length before and after reflection on micro-reflecting surface 1, therefore the optical path difference is 0. However, incident rays 1B and 2A have different optical path differences before and after reflection because they are incident on different positions on different micro-reflecting surfaces. Similarly, incident rays 2B and 3A also have optical path differences before and after reflection. The optical path difference d for both is: d = p × sin(2θ);

[0071] Where p represents the size of the micro-reflective surface, specifically the pitch of the orthographic projection of the micro-reflective surface onto the substrate surface along a set direction, and θ represents the tilt angle of the micro-reflective surface.

[0072] If the aforementioned optical path difference is an integer multiple of the wavelength λ of the incident light, the phase difference of the reflected light can be considered to be an integer multiple of 2π. Since the phase is periodic, an integer multiple of 2π in phase difference can be considered as the same phase. However, in reality, variations in the size and tilt angle of the micro-reflective surfaces usually cannot guarantee that the phase difference of the reflected light rays at the edges of two adjacent micro-reflective surfaces will be an integer multiple of 2π. Therefore, the reflected light will act as secondary waves with different phases, producing a diffraction effect that influences the angle control of the light rays.

[0073] In Figure 9, parallel dashed lines represent the wavefronts of incident or reflected light. The phase difference between two adjacent dashed lines is 2π. As shown in Figure 9, the parallel dashed lines of the reflected light wavefront 1 of micro-reflecting surface 1 and the reflected light wavefront 2 of micro-reflecting surface 2 are not aligned, and the parallel dashed lines of the reflected light wavefront 2 of micro-reflecting surface 2 and the reflected light wavefront 3 of micro-reflecting surface 3 are also not aligned. This indicates that there is a phase difference between the light reflected by adjacent micro-reflecting surfaces. The superposition of the phase interference of secondary waves with different phases makes the diffraction effect obvious.

[0074] Based on the above principle, this application embodiment adjusts the micro-reflective surfaces to make the reflected light from adjacent micro-reflective surfaces have the same phase (i.e., the phase difference is an integer multiple of 2π), thereby reducing the influence of diffraction.

[0075] In some embodiments, the phase of the reflected light can be made the same by adjusting the height of adjacent microreflective surfaces.

[0076] Specifically, as shown in Figure 10, by raising the vertical position of some micro-reflective surfaces on the substrate, the heights of adjacent micro-reflective surfaces within the same reflective group can be made different. It should be noted that the height of the micro-reflective surface in this case is a correction height. The correction height of the micro-reflective surface refers to the distance from the bottom edge s1 of the side corresponding to the inclined surface of the supporting structure along the set direction to the surface of the substrate; that is, the height by which the micro-reflective surface is raised. In the cross-sectional shape of the supporting structure along the set direction, the greater the difference between the top edge s2 and the bottom edge s1 of the side corresponding to the inclined surface, the larger the tilt angle of the micro-reflective surface; conversely, the smaller the difference between the bottom edge s1 and the top edge s2, the smaller the tilt angle of the micro-reflective surface.

[0077] When adjacent micro-reflective surfaces have different heights, by adjusting the height to an appropriate value, the phase difference of the projected light reflected by the adjacent micro-reflective surfaces can be made to be an integer multiple of 2π. This allows the reflected light from adjacent micro-reflective surfaces to be regarded as the same wavefront, which is equivalent to treating all micro-reflective surfaces in the same reflection group as a whole reflection surface, thus reducing the impact of diffraction.

[0078] As shown in Figure 10, in a cross-section along a set direction, the height difference between adjacent micro-reflective surfaces within the same reflective group satisfies: h i -h i-1 =p i-1 tanθ i-1 -nλ / (2(cosθ i-1 ) 2 );

[0079] Where n is a positive integer, i is a positive integer, and h i h represents the height of the i-th micro-reflective surface. i-1p represents the height of the (i-1)th micro-reflective surface. i-1 θ represents the pitch of the (i-1)th micro-reflective surface projected onto the substrate along a set direction. i-1 λ represents the tilt angle of the (i-1)th micro-reflective surface relative to the plane of the substrate, and λ represents the wavelength of the incident projected light.

[0080] The height difference between adjacent micro-reflective surfaces satisfies the above formula, which makes the optical path difference of the light rays incident on the edge positions of two adjacent micro-reflective surfaces before and after reflection an integer multiple of λ. Then the phase of the reflected light will be an integer multiple of 2π and become in phase.

[0081] Taking the height correction method shown in Figure 10 as an example, the dimensions of each micro-reflective surface within the same reflective group (the pitch p of the micro-reflective surface's orthographic projection onto the substrate along a set direction) can be the same. The support structure f corresponding to micro-reflective surface 1 can be directly mounted on the substrate 122, and the height h1 of micro-reflective surface 1 can be 0. Micro-reflective surfaces 2 and 3 can be raised to different degrees. The heights h2 of micro-reflective surface 2 and h3 of micro-reflective surface 3 are both higher than that of micro-reflective surface 1. The heights of micro-reflective surface 2 and 3 are also different; the height h2 of micro-reflective surface 2 can be greater than the height h3 of micro-reflective surface 3. The values ​​of h1, h2, and h3 must satisfy the above formula to ensure that the reflected light from the three micro-reflective surfaces has the same phase, as shown in Figure 10, where the parallel dashed lines of the reflected light wavefronts 1, 2, and 3 of the three micro-reflective surfaces are aligned.

[0082] Figure 10 is for illustrative purposes only. In actual implementation, the height of each micro-reflective surface only needs to satisfy the above formula as long as the height difference between adjacent micro-reflective surfaces is met. Here, the number of micro-reflective surfaces contained in a reflection group and the height variation law of the micro-reflective surfaces are not limited.

[0083] In specific implementation, a film layer of a certain thickness (the same as the height of elevation) can be formed on the substrate 122 at the positions corresponding to the micro-reflective surfaces 2 and 3. Then, a support structure f can be formed on the film layer. Finally, a reflective layer 121 can be covered on the support structure f to form the micro-reflective surfaces 2 and 3, so that the micro-reflective surfaces 2 and 3 can be raised to different degrees.

[0084] In some embodiments, the phase of the reflected light can be made the same by adjusting the size of the micro-reflective surface.

[0085] Specifically, as shown in Figure 11, assuming all micro-reflective surfaces have the same height, the dimensions of micro-reflective surfaces located within the same reflection group along a set direction can be set to satisfy: p i ×sin(2θ i )=nλ;

[0086] Where n is a positive integer, i is a positive integer, and p i θ represents the pitch of the orthographic projection of the i-th micro-reflective surface onto the substrate along a set direction. i The tilt angle of the i-th micro-reflective surface relative to the plane of the substrate is represented by λ, and the wavelength of the incident projected light is represented by λ. The direction can be set to either horizontal or vertical.

[0087] If the size of each micro-reflecting surface in the reflector group satisfies the above formula, the optical path difference of the light rays incident on the edge positions of two adjacent micro-reflecting surfaces before and after reflection will be an integer multiple of λ, and then the phase difference of the reflected light will disappear.

[0088] In some embodiments, the tilt angle θ of each micro-reflective surface located in the same reflective group along a set direction can be the same. If the size of the micro-reflection, i.e. the pitch p of the orthographic projection on the substrate along the set direction, is set to a suitable value that satisfies the above formula, the pitch can be set to a fixed value, and then the size of each micro-reflective surface in the same reflective group will be the same.

[0089] In some embodiments, the size of the micro-reflective surface can be flexibly changed so that the size of each micro-reflective surface meets the above requirements. In this case, the sizes of the micro-reflective surfaces within the same reflection group may not be exactly the same.

[0090] In practical implementation, the lower limit of the micro-reflective surface size is 1μm, which is smaller than the pixel size of the image on the projection screen. Therefore, a reasonable value can be selected within this range, taking into account factors such as cost and manufacturing difficulty.

[0091] Taking the size adjustment method shown in Figure 11 as an example, the height of each micro-reflecting surface in the same reflective group can be the same. The values ​​of p1, p2, and p3 need to satisfy the above formula, so that the phase of the reflected light from the three micro-reflecting surfaces is the same. As shown in Figure 11, the parallel dashed lines of the reflected light wavefronts 1, 2, and 3 of the three micro-reflecting surfaces are aligned.

[0092] Figure 11 is for illustrative purposes only. In actual implementation, as long as the size of each micro-reflective surface satisfies the above formula, the number of micro-reflective surfaces contained in a reflection group and the size variation law of the micro-reflective surfaces are not limited here.

[0093] It is worth noting that when adjusting the height and size of the micro-reflective surface, the relationship with the wavelength λ of the incident light must be taken into account. For a light source with only one color as coherent light, the wavelength of that color must be considered. When a three-color laser light source is used, the incident light is the wavelength of the three-color laser. Then, the wavelengths of the red, green, and blue lasers can be substituted into the above formula for calculation. By adjusting, the overall result can be optimized, and the diffraction effect of the three-color laser can be reduced at the same time.

[0094] After adjusting the height or size of the micro-reflective surface as described above, all micro-reflective surfaces within the same reflection group can be considered as a single reflective surface. Taking a micro-reflective surface as a square with a side length of 10 μm and an incident light wavelength of 550 nm as an example, before adjusting the micro-reflective surface, the minimum adjustable angle was 3.2 (deg). After adjusting the micro-reflective surface, the minimum adjustable angle can be reduced to 0.05 (deg), thereby significantly reducing the influence of diffraction.

[0095] As shown in Figures 6 and 12, the projection screen further includes an adhesive layer 13, which is located between the surface layer 11 and the reflective structure layer 12, and is used to bond and fix the surface layer 11 and the reflective structure layer 12 together. The adhesive layer 13 can be made of adhesive materials such as epoxy resin, acrylic resin, or silicone resin, and is not limited thereto.

[0096] In some embodiments, as shown in FIG6, the support structure f of the reflective structure layer 12 is located on the side opposite to the adhesive layer 13; the adhesive layer 13 bonds the surface layer 11 and the reflective structure layer 12 together. The support structure f can be fabricated using a thermoplastic material and a 3D printing process.

[0097] The support structure f of the reflective structure layer 12 faces the front of the projection screen, and the substrate 122 of the reflective structure layer 12 is in contact with the adhesive layer 13. After the projection light is incident on the projection screen, it needs to pass through the substrate 122 and the support structure f before it can enter the reflective layer 121. Therefore, the substrate 122 and the support structure f need to be made of light-transmitting materials.

[0098] The substrate 122 can be made of materials such as PET, PEN, PC, PMMA, TAC, COP, TPU, PVC, PI, PA, PE, PP, etc., and there are no restrictions here.

[0099] The reflective layer 121 located on the support structure f can be made of a reflective metallic material, or the reflective layer 121 can also be made of a resonant structure, so as to selectively reflect the incident projection light, thereby improving the contrast of the projection light.

[0100] In some embodiments, as shown in FIG12, the surface layer 11 may be a diffusion layer, which may include a substrate 111 and a diffusion material 112 located on one side surface of the substrate 111. The substrate 111 may be made of materials such as PET, PEN, PC, PMMA, TAC, COP, TPU, PVC, PI, PA, PE, PP, etc. The diffusion material 112 may be made of materials such as silica particles, aluminum oxide particles, titanium oxide particles, cerium oxide particles, zirconium oxide particles, tantalum oxide particles, zinc oxide particles, magnesium fluoride particles, etc.

[0101] In some embodiments, the diffusion layer may consist only of the substrate 111, which acquires light-diffusing properties by doping diffusion particles into the substrate 111. Alternatively, the surface of the substrate 111 may be an uneven surface. This uneven surface can be formed by sandblasting or alkaline treatment of the surface of the substrate 111, and is not limited thereto. The substrate 111 can provide a certain degree of light diffusion and atomization, thereby expanding the viewing angle and reducing ceiling glare.

[0102] In some embodiments, the diffusion layer can be an anisotropic diffusion layer. Anisotropic diffusion means that the degree of light diffusion can vary in different directions. In this embodiment, the anisotropic diffusion layer can diffuse light to a greater extent along the horizontal direction x than along the vertical direction y. Projection screens are typically fixed to a wall or suspended high up, or integrated with the projection device. The horizontal direction x refers to the direction parallel to the horizontal plane where the viewer is located, and the vertical direction y is perpendicular to the horizontal direction x. Since viewers do not need a large viewing angle in the vertical direction when viewing a projection screen, but do 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.

[0103] To achieve anisotropic diffusion, multiple strip-shaped prism structures 112a can be configured, as shown in Figure 13. The strip-shaped prism structure 112a can be a lenticular structure, or, as shown in Figure 14, a prism structure. As shown in Figures 13 and 14, the axis of the strip-shaped prism structure 112a is parallel to the vertical direction y and arranged sequentially along the horizontal direction x.

[0104] The strip-shaped rib structure 112a in the anisotropic diffusion layer can be made of materials such as acrylic resin or thermoplastic polyurethane (TPU) through an embossing process, and there is no limitation here.

[0105] Based on the same inventive concept, this application also provides a projection system, as shown in FIG1. ​​The projection system includes: a projection device 2 and a projection screen 1 located on the light-emitting side of the projection device 2.

[0106] Figure 15 is a schematic diagram of the projection device provided in an embodiment of this application.

[0107] As shown in Figure 15, the projection device includes: a light source device 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 light source device 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.

[0108] The light source device 21 can be a laser light source device. The 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 the laser light source device uses a monochromatic laser, the laser display device also needs to include a color wheel for color conversion. The monochromatic laser, in conjunction with the color wheel, can achieve the purpose of emitting different primary colors of light in a sequential manner. When the laser light source device uses a laser capable of emitting multiple colors of laser light, it is necessary to control the laser light source to emit different colors of laser light as primary colors in a sequential manner.

[0109] In this embodiment, the light source device can be a three-color laser light source device, which can be a laser that emits three primary color lasers, such as an MCL laser; or it can include a red laser, a green laser, and a blue laser that emit three primary color lasers 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.

[0110] The illumination light path 22 is located on the light-emitting side of the light source device 21. The illumination light path 22 collimates and homogenizes the emitted light from the light source device 21, and also allows the emitted light from the light source device 21 to enter the display element 23 at a suitable angle. The illumination light path 22 may include multiple lenses or lens groups, which are not limited here.

[0111] 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.

[0112] Lens 24 is used to image the light emitted from display element 23 and to project the image onto projection screen 1.

[0113] In this embodiment, the projection device 2 can be an ultra-short-throw projection device, that is, the lens 24 in the projection device is an ultra-short-throw lens. Using an ultra-short-throw projection device can greatly shorten the distance between the projection device 2 and the projection screen 1, and can achieve large-size image display while shortening the projection distance.

[0114] The projection screen 1 is located on the light-emitting side of the lens in the projection device. The projection screen 1 includes a surface layer and a reflective structure layer. The reflective structure layer includes a substrate, multiple support structures, and a reflective layer. The reflective layer, located on the inclined surface of the support structures, forms multiple micro-reflective surfaces arranged in an array. These micro-reflective surfaces receive the projected light emitted from the projection device and reflect it towards the viewer, ensuring high gain at each position on the projection screen. The micro-reflective surfaces are grouped so that the pixels of the image projected onto the projection screen cover multiple reflection groups. The projected light reflected by each micro-reflective surface within the same reflection group has the same phase. Therefore, the reflected light from different micro-reflective surfaces within the same reflection group can be approximated as a plane wave, and all micro-reflective surfaces within the same reflection group can be considered as a single reflective surface, significantly reducing the effects of diffraction and improving the controllability of the micro-reflective surface angle.

[0115] 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.

[0116] 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: Surface layer; and A reflective structural layer is located on the side of the surface layer furthest from the viewer; The reflective structure layer includes: Substrate; Multiple support structures are located on the surface of the substrate; the surface of each support structure away from the substrate is inclined relative to the plane of the substrate; and A reflective layer is applied to the inclined surface of the supporting structure, forming multiple micro-reflective surfaces; these multiple micro-reflective surfaces are arranged in an array; these multiple micro-reflective surfaces are used to receive the projected light emitted from the projection device and reflect it towards the viewer; The plurality of micro-reflective surfaces are divided into a plurality of reflection groups. The pixels of the image projected onto the projection screen by the projected light cover a plurality of the reflection groups. The projected light reflected by adjacent micro-reflective surfaces within the same reflection group has the same phase.

2. The projection screen as described in claim 1, characterized in that, The heights of adjacent micro-reflective surfaces within the same reflective group are different; the height of the micro-reflective surface is the distance from the bottom of the side corresponding to the inclined surface in the cross-sectional shape of the support structure along a set direction to the surface of the substrate. The set direction is either horizontal or vertical. The horizontal direction is parallel to the horizontal plane, and the vertical direction is located in the plane of the substrate and is perpendicular to the horizontal direction.

3. The projection screen as described in claim 2, characterized in that, The height difference between adjacent microreflective surfaces within the same reflective group satisfies: h i -h i-1 =p i-1 tanθ i-1 -nλ / (2(cosθ i-1 ) 2 ); Where n is a positive integer, i is a positive integer, and h i h represents the height of the i-th micro-reflective surface. i-1 p represents the height of the (i-1)th micro-reflective surface. i-1 θ represents the pitch of the (i-1)th microreflective surface projected onto the substrate along the predetermined direction. i-1 λ represents the tilt angle of the (i-1)th micro-reflective surface relative to the plane of the substrate, and λ represents the wavelength of the incident projected light.

4. The projection screen as described in claim 1, characterized in that, All the micro-reflective surfaces have the same height. The height of the micro-reflective surface is the distance from the bottom of the side corresponding to the inclined surface in the cross-sectional shape of the support structure along a set direction to the surface of the substrate. The set direction is either horizontal or vertical. The horizontal direction is parallel to the horizontal plane, and the vertical direction is located in the plane of the substrate and is perpendicular to the horizontal direction. The pitch of the micro-reflective surfaces within the same reflective group, projected onto the substrate along the predetermined direction, satisfies: p i sin(2θ i )=nλ; Where n is a positive integer, i is a positive integer, and p i θ represents the pitch of the orthographic projection of the i-th microreflective surface onto the substrate. i λ represents the tilt angle of the i-th micro-reflective surface relative to the plane of the substrate, and λ represents the wavelength of the incident projected light.

5. The projection screen as described in claim 4, characterized in that, The micro-reflective surfaces within the same reflective group have the same pitch in the orthographic projection of their surfaces onto the substrate along the set direction.

6. The projection screen as described in claim 5, characterized in that, The pitch of the micro-reflective surface in the orthographic projection of the substrate along the set direction is greater than or equal to 1 μm, and smaller than the pixel size of the image projected onto the projection screen by the projection light.

7. The projection screen as described in any one of claims 1 to 6, characterized in that, The plurality of support structures are arranged closely along the horizontal and vertical directions, the horizontal direction being parallel to the horizontal plane, and the vertical direction being located in the plane of the substrate and perpendicular to the horizontal direction; The angle between the inclined surface of the support structure and the plane of the substrate along the horizontal direction is the first angle, and the angle between the inclined surface of the support structure and the plane of the substrate along the horizontal direction is the second angle. The first angle and the second angle are set according to the incident direction and incident angle of the projected light.

8. The projection screen as described in claim 7, characterized in that, The tilt direction and tilt angle of each micro-reflective surface within the same reflection group are the same; the tilt direction and / or tilt angle of the micro-reflective surfaces within different reflection groups are different.

9. The projection screen as described in claim 8, characterized in that, The projection screen has an axisymmetric structure, and the axis of symmetry of the projection screen is perpendicular to the horizontal direction; The tilt direction and tilt angle of all the micro-reflective surfaces are symmetrically distributed with respect to the axis of symmetry.

10. The projection screen as described in claim 8, characterized in that, The projection screen also includes: An adhesive layer, located between the surface layer and the reflective structure layer, is used to bond the surface layer and the reflective structure layer together.

11. The projection screen as described in claim 8, characterized in that, The surface layer is a diffusion layer, and the diffusion layer diffuses light to a greater extent along the horizontal direction than it diffuses light to a greater extent along the vertical direction.

12. 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 11; 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 light source device, is used to modulate the emitted laser light from the three-color laser light source device to form a display image; and a lens, located on the light-emitting side of the display element, projects the emitted light from the display element into an image.

Images