Transparent projection device

Abstract

The invention provides a transparent projection device which comprises a transparent projection device body and an antireflection film arranged on at least one side of the transparent projection device body, and image light enters the antireflection film and the transparent projection device body at an inclined angle. The anti-reflection film is used for reducing the intensity of reflected light which is reflected by the image light at an inclined angle through a mirror surface on the surface of the transparent projection device body and enters the optimal viewing area, so that light spots are prevented, and the transparent projection device body reflects the image light to the optimal viewing area through diffuse reflection.

Description

Technical Field

[0001] This application relates to the field of optoelectronic technology, and in particular to a transparent projection device. Background Technology

[0002] Transparent projection film is an optical film that can display projected images while remaining transparent. It has a simple structure, low cost, and stable performance, and possesses broad market prospects. Currently, it is used in various applications such as subways, automobiles, and advertising.

[0003] For front projection films, because the front and back surfaces of a transparent projection film are smooth, projector light will experience specular reflection at the interface between the film and the air, resulting in glare that enters the user's field of vision and creates a dazzling glare effect, also known as a "glare spot" effect. This severely affects the projection quality, causing discomfort and even peripheral vision when viewing the projected image. Existing technologies have attempted to mitigate this effect using polarized projection, but the results have been unsatisfactory. Simultaneously, the specular reflection caused by the smooth surface of the projection film also reflects ambient light, interfering with the projected image.

[0004] Therefore, there is an urgent need to provide a transparent projection device to solve the problem of projector light spots. Summary of the Invention

[0005] To address the aforementioned issues, this application provides a transparent projection device that can resolve the problem of projector light spots.

[0006] To achieve the above objectives, this application provides a transparent projection device, including a transparent projection device body and an antireflective film disposed on at least one side of the transparent projection device body. Image light is incident on the antireflective film and the transparent projection device body at an oblique angle. The antireflective film is used to reduce the intensity of the reflected light incident on the optimal viewing area by the image light passing through the specular reflection of the surface of the transparent projection device body at an oblique angle, thereby preventing light spots. The transparent projection device body reflects the image light to the optimal viewing area through diffuse reflection.

[0007] In a preferred embodiment, the antireflective film is disposed on the side of the transparent projection device body facing the projector.

[0008] In a preferred embodiment, the antireflective film is disposed on both the side of the transparent projection device body facing the projector and the side facing away from the projector.

[0009] In a preferred embodiment, the transparent projection device body includes two outer layers with substantially the same refractive index and an intermediate layer inserted between the two outer layers, the intermediate layer having a different refractive index than the two outer layers.

[0010] In a preferred embodiment, the transparent projection device body includes: the contact surfaces between two adjacent layers of the two outer layers and the middle layer are textured and parallel to each other.

[0011] In a preferred embodiment, texturing the contact surfaces between two adjacent layers in the two outer and middle layers is used to achieve diffuse reflection.

[0012] In a preferred embodiment, the contact surfaces between two adjacent layers in the two outer layers and the middle layer have a Fresnel textured structure.

[0013] In a preferred embodiment, the Fresnel textured structure has a diffuse microstructure on the side facing the projector.

[0014] In a preferred embodiment, at least one of the two outer layers is made of a polymer material or a glass material.

[0015] In a preferred embodiment, the intermediate layer is formed by a single layer or by a stack of multiple layers.

[0016] In a preferred embodiment, the reflection angle of the reflected light of the image light incident on the optimal viewing area through specular reflection from the surface of the transparent projection device body is 10-30 degrees.

[0017] In a preferred embodiment, when the antireflective film is a single-layer material, the thickness of the antireflective film is 90-100 nm.

[0018] In a preferred embodiment, when the antireflective coating is a four-layer material, the thickness of the antireflective coating is 250nm-300nm.

[0019] In a preferred embodiment, when the antireflective coating is a six-layer material, the thickness of the antireflective coating is 240nm-350nm.

[0020] It should be understood that the above general description of this application and the following detailed description are exemplary and illustrative and are intended to provide further explanation of the claimed application. Attached Figure Description

[0021] The accompanying drawings are included to provide a further understanding of the present application and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the present application and, together with the description, serve to explain the principles of the present application. In the drawings: Figure 1 This is a schematic diagram of a transparent projection device and its application scenario provided in Embodiment 1 of this application; Figure 2 This is a schematic diagram of the structure of a transparent projection device shown separately; Figure 3This is a schematic diagram of a transparent projection device provided in Embodiment 2 of this application; Figure 4 This is a schematic diagram of a transparent projection device and its application scenario provided in Embodiment 3 of this application; Figure 5 This is a schematic diagram analyzing the causes of light spots in existing technologies; Figure 6 This is a diagram illustrating how the light spot problem is alleviated simply by reducing the distance between the projector and the transparent projection screen; Figure 7 This is a diagram illustrating how the light spot problem is alleviated simply by increasing the placement height of the projector; Figure 8 It is a schematic diagram of a system optical path transmission path with actual parameter configuration; Figure 9 Is Figure 8 A schematic diagram of the optical path transmission path of the system after only increasing the placement height of the projector. Detailed Implementation

[0022] Now, reference will be made in detail to exemplary embodiments of this application, examples of which are illustrated in the accompanying drawings. Wherever possible, throughout the drawings, the same reference numerals will be used to denote the same or similar components.

[0023] The shapes, dimensions, ratios, angles, and quantities disclosed in the accompanying drawings used to describe embodiments of this application are merely examples, and therefore, this application is not limited to the details illustrated. Similar reference numerals always denote similar elements. In the following description, detailed descriptions will be omitted where it is determined that such detailed descriptions unnecessarily obscure the essence of this application.

[0024] Where the terms “comprising,” “having,” and “including” are used as described in this specification, additional parts may be added unless “only” is used. Singular terms may include plural forms unless otherwise stated.

[0025] When interpreting a component, it is interpreted as including a range of errors, although this is not explicitly described.

[0026] In the description of embodiments of this application, when a structure (e.g., an electrode, wire, wiring, layer, or contact) is described as being formed on top of / below the upper / lower portion of another structure or other structures, this description should be understood to include cases where these structures are in contact with each other, and further includes cases where a third structure is disposed therebetween.

[0027] In describing temporal relationships, for example, when time sequence is described as “after,” “following,” “next,” and “before,” discontinuous cases may be included unless “exactly” or “immediately following” is used.

[0028] It should be understood that although the terms "first," "second," etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are merely used to distinguish one element from another. For example, without departing from the scope of this application, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element.

[0029] The “X-axis direction,” “Y-axis direction,” and “Z-axis direction” should not be interpreted solely by their geometric relationship of being perpendicular to each other, but rather can have a broader directionality within the scope of the functionality of the components in this application.

[0030] The term "at least one" should be understood to include any and all combinations of one or more of the related listed items. For example, "at least one of the first, second, and third items" means a combination of all items proposed from the first, second, and third items, as well as two or more of the first, second, or third items.

[0031] Features of the various embodiments of this application may be connected or combined with each other in part or in whole, and may operate in various ways and be technology-driven, as will be fully understood by those skilled in the art. Embodiments of this application may be performed independently of each other, or may be performed together in an interdependent relationship.

[0032] Firstly, the inventors of this application have conducted an in-depth analysis of the causes of light spots in the prior art, referring to... Figure 5 As shown, Figure 5 The thickness of the transparent projection screen and the phase position of the projector are exaggerated to more clearly show the changes in the light path transmission. Projector 2 only shows the aperture 21 of the projection lens, and only representatively shows the transmitted light beams from three typical fields of view (center field of view, upper boundary field of view, and lower boundary field of view), where the beams from each field of view only represent the main ray, upper edge ray, and lower edge ray. Furthermore... Figure 5 The diagram only shows the reflection and transmission of light rays on the front surface 41 of the transparent projection screen 4, and the incident point on the diffuse reflection surface 42. This is sufficient to explain the principle described later. Therefore, the light rays transmitted through the diffuse reflection surface 42 and the light rays diffusely reflected by the diffuse reflection surface 42 are not shown. Furthermore, to simplify the complexity of the drawing, Figure 5 The refraction of light rays from the front surface 41 due to refraction is ignored; similarly, this refraction does not affect the subsequent explanation of the principle. Meanwhile... Figure 5 The microstructural features of the diffuse reflective surface 42 are not shown in the figure. Depend on Figure 5 As can be seen, after the central field-of-view beam vci is incident on the front surface 41 of the transparent projection screen 4, part of it undergoes specular reflection to form the central field-of-view specularly reflected beam vcr, and part of it undergoes transmission to form the central field-of-view transmitted beam vct. A convergence point cf1 is formed at the diffuse reflection surface 42, where the diffuse reflection light of the central field of view is formed and can be received by the human eye 31. The diffuse reflection light... Figure 5 It is not shown in the middle.

[0033] After the upper boundary field of view vui is incident on the front surface 41 of the transparent projection screen 4, part of it undergoes specular reflection to form the specularly reflected upper boundary field of view beam vur, and part of it undergoes transmission to form the transmitted upper boundary field of view beam vut. These rays converge at a point uf1 on the diffuse reflection surface 42, where diffuse reflection of the upper boundary field of view is formed and can be received by the human eye 31. Figure 5 It is not shown in the middle.

[0034] When the lower boundary field of view (vdi) is incident on the front surface 41 of the transparent projection screen 4, part of it undergoes specular reflection to form the specularly reflected beam (vdr) of the lower boundary field of view, and part of it undergoes transmission to form the transmitted beam (vdt) of the lower boundary field of view. These beams converge at a point (df1) on the diffuse reflection surface 42, where the diffuse reflection light of the upper boundary field of view is formed and can be received by the human eye 31. Figure 5 It is not shown in the middle.

[0035] For the specularly reflected light rays formed on the front surface 41 for each field of view, the central field-of-view specularly reflected beam vcr, the upper boundary field-of-view specularly reflected beam vur, and the lower boundary field-of-view specularly reflected beam vdr each form a convergence point (achieving imaging) at a certain distance outside the front surface 41 before continuing to propagate. For example, the convergence point formed by the central field-of-view specularly reflected beam vcr is cf2, the convergence point formed by the upper boundary field-of-view specularly reflected beam vur is uf2, and the convergence point formed by the lower boundary field-of-view specularly reflected beam vdr is df2. The projector spot seen by the user is caused by at least a portion of the light rays from at least a portion of these reflected beams entering the human eye 31 and being seen by the human eye. For example... Figure 5 The image specifically shows the transmission path of the human eye 31 in the mirror reflection beam vur of the upper boundary field of view. Thus, the human eye can see the pixel of the upper boundary field of view, and the human eye 31 can receive a very strong light intensity from the pixel, that is, a very high brightness, thus forming a dazzling light spot. Figure 8An exemplary diagram illustrates the optical path transmission of a system employing a transparent projection screen with a practical thickness configuration and a projector with a practical placement position and a practical aperture size. It can be seen that the human eye can receive partially reflected light from a portion of the field of view. Therefore, the formation of a light spot requires the simultaneous fulfillment of the following two conditions: Condition 1: At least part of the field of view reflected by the light source on the front surface 41 can eventually be received by the human eye; Condition 2: The brightness of the received field of view is high.

[0036] The spot problem can be solved by breaking at least one of conditions 1 and 2.

[0037] The inventors tested and analyzed the schemes that violated the two conditions separately.

[0038] To disrupt condition 1, one approach is to ensure that the light reflected from the front surface 41 across the entire field of view reaches the ground or only incident at a height below the viewer's eye level before reaching the location of the person 3. This can be achieved by reducing the distance between the projector 2 and the transparent projection screen 4, or by increasing the placement height of the projector 2. Figure 6 and Figure 7 The analysis results for two schemes are shown: one is to reduce the distance between the projector 2 and the transparent projection screen 4, and the other is to increase the placement height of the projector 2. The reference numerals in the figures are... Figure 5 The meanings of the corresponding labels in the attached figures are the same, and will not be repeated here. (Comparison) Figure 6 and Figure 5 and comparison Figure 7 and Figure 5 It is evident that both schemes can prevent the human eye 31 from receiving the entire field of vision reflected from the front surface 41. (The accompanying reference numerals are not included in this translation.) Figure 1 The physical meanings of the same components and light rays are the same, so I will not repeat them here. Figure 9 The diagram illustrates the optical path transmission of a system employing a transparent projection screen with an actual thickness configuration and a projector with an actual placement position and an actual aperture size, in comparison. Figure 9 and Figure 8 , Figure 9 The proposed solution increases the placement height of the projector 2, thereby preventing the human eye 31 from receiving the light reflected from the surface in front of the transparent projection screen across the entire field of view.

[0039] It should be noted that although the human eye 31 can no longer receive all the light reflected from the front surface 41, due to the diffuse reflection effect of the diffuse reflection surface 42, at least a portion of the field of view, after being transmitted from the front surface 41 and diffusely reflected by the diffuse reflection surface 42, can still ultimately reach the human eye 31. This diffusely reflected light is precisely what is needed to achieve transparent projection. Therefore, this solution solves the problem of light spots without affecting the projection display. However, in practical applications, the placement height of the projector 2 is often limited. Even for short-throw projectors, there is a minimum limit to the distance between them and the projection screen 4. This minimum limit is determined by the projection ratio, i.e., the ratio of the projection distance to the width of the projected image. In short, under the constraints of many practical scenarios, the projector 2's height cannot reach the minimum height required to eliminate light spots, and the minimum distance between the projector 2 and the projection screen 4 cannot reach the maximum distance required to eliminate light spots. This makes condition 1 difficult to violate.

[0040] The direct reason for condition 2 is that the divergence angle of the light rays reflected from the front surface 41 by each field of view incident on the human eye 31 is small (resulting in energy concentration) and the reflectivity is high. The reasons for the small divergence angle include the small original divergence angle of the light beams from each field of view before incident on the front surface 41, and the fact that the front surface 41 does not amplify this divergence angle. The small original divergence angle is a factor that is difficult to control and can be disregarded. The reason the front surface 41 does not amplify this divergence angle is that the reflection from the surface of the front surface 41 is specular reflection, which is due to the fact that the front surface 41 is a smooth plane. However, a smooth surface on the front surface 41 is a necessary condition for clearly seeing the scene behind the projection screen in transparent projection. Therefore, reducing the reflectivity of the front surface 41 is a feasible solution. To achieve this reduction, an anti-reflection coating can be considered for the front surface 41.

[0041] However, it should be noted that the principle of increasing transmission and reducing reflection of antireflection coatings determines that their thickness and material selection are related to the incident angle of the incident light. In other words, the same antireflection coating has good antireflection performance for light incident at one angle, but its antireflection performance will be poor for light incident at other angles.

[0042] Currently, the application of antireflective coatings in existing technologies typically addresses the glare problem caused by ambient light reflection on product surfaces. This specific issue dictates that the design and optimization requirements for antireflective coatings are often geared towards achieving antireflection and anti-reflection for perpendicularly incident light. However, in the field of transparent projection described in this patent application, the light requiring antireflection and anti-reflection is the portion of the reflected image light that is incident on a transparent projection screen at an oblique angle and can be received by the human eye through specular reflection. This differs significantly from the application scenarios and specific functions of antireflective coatings in existing technologies.

[0043] The specific implementation of the embodiments of this application is described in detail below.

[0044] Example 1 Figure 1 A schematic diagram of a transparent projection device and its application scenarios provided in this application is shown. Figure 2 A schematic diagram of the transparent projection device is shown separately. (See attached diagram.) Figure 1 As shown, the transparent projection device 1 in this embodiment includes a transparent projection device body 10 and an anti-reflection film 11 disposed on one side of the transparent projection device body. The projected image light projected by the projector 2 is obliquely incident on the transparent projection device 1. In this embodiment, specifically, the projector 2 is disposed at an obliquely above the transparent projection device 1. In other alternative embodiments, the projector 2 can also be disposed at an obliquely below the transparent projection device 1. The oblique incident of the image light projected by the projector 2 on the transparent projection device 1 means that the central field-of-view beam rc1 of the image light projected by the projector 2 is obliquely incident on the transparent projection device 1. Preferably, the upper boundary field-of-view beam of the image light is also obliquely incident on the transparent projection device 1.

[0045] The focal plane of the image light projected by the projector 2 is located inside the transparent projection device body 10. Therefore, the reflected light generated at the surface of the transparent projection device body 10 is harmful light, which is the main cause of projector light spots.

[0046] In this embodiment, the antireflection film 11 is used to reduce the intensity of reflected light that is incident at an angle onto the surface of the transparent projection device body 10 on which the antireflection film 11 is applied, and that is incident into the optimal viewing area through specular reflection, thereby preventing light spots caused by specular reflection at this surface by the projector 2. The antireflection film 11 can utilize the principle of destructive interference to maximize the elimination of reflected light energy, thereby increasing the proportion of transmitted light energy. Furthermore, the transparent projection device body reflects the image light to the optimal viewing area through diffuse reflection.

[0047] It should be noted that, as discussed earlier, although the technique of using antireflective coatings to reduce reflectivity and increase light transmittance is considered existing technology in isolation, this application uses antireflective coatings for a specific application scenario. Specifically, it aims to eliminate the intensity of reflected light from a projected image, incident at an overall angle, through specular reflection from the surface of the transparent projection device, thus preventing light spots. This approach differs significantly from existing technologies for two reasons.

[0048] Firstly, the ultimate purpose of antireflective coatings in existing technologies differs from that in this patent. For example, in the prior art disclosed in Chinese Patent CN104298063B, antireflective coatings are applied to transparent projection films to reduce diffuse reflection of ambient light on the front surface of the projection film, alleviating the visual phenomenon of "dirty glass." In this prior art, since the problem is related to the influence of ambient light, the antireflective coating is mainly optimized for vertically incident light. Another example is the prior art disclosed in Chinese Patent CN1087113163B, which uses antireflective coatings to prevent ghosting caused by secondary reflections within the transparent projection film. These two types of prior art represent the mainstream purpose and design concept of applying antireflective coatings to transparent projection films in the current industry, which differs significantly from the role and design concept of the antireflective coating in the transparent projection device of this invention. In this embodiment, the antireflective coating 11 is disposed on the side of the transparent projection device body 10 facing the projector 2. Furthermore, since the antireflection film 11 is used to reduce the intensity of reflected light from the overall obliquely incident projected image light, the thickness and material selection of the antireflection film 11 need to be designed for obliquely incident light in order to specifically solve the light spot problem of the projector 2.

[0049] Secondly, in this embodiment, an antireflective coating that prevents specular reflection is organically combined with a transparent projection device body that reflects image light to the optimal viewing area through diffuse reflection. This is because the antireflective coating in this embodiment reduces the intensity of reflected light incident on the optimal viewing area by specular reflection of image light passing through the surface of the transparent projection device body at an oblique angle. Image light incident at this oblique angle will be incident on the optimal viewing area through specular reflection, causing a light spot phenomenon. Simultaneously, if the transparent projection device body still uses specular reflection to project image light, for example, presenting an image behind the transparent projection device body in the form of a virtual image, the presentation of this virtual image will also be significantly affected by the antireflective coating and become very dark. This is because the light entering the optimal viewing area corresponding to the virtual image almost matches the working angle range of the antireflective coating, making the virtual image almost invisible. In this embodiment, the transparent projection device body reflects image light to the optimal viewing area through diffuse reflection, so that the imaging surface of the image light can be located on the transparent projection device body, that is, a real image is formed. Due to the effect of diffuse reflection, the field of view of the reflected image light can be increased. In this way, some angles of light in the formed real image will still be affected by the anti-reflection film, but other light with expanded field of view will still be incident on the optimal viewing area, so that the real image formed by diffuse reflection is still clearly visible.

[0050] like Figure 2As shown, the transparent projection device body 10 in this embodiment includes two outer layers with essentially the same refractive index, hereinafter referred to as the first outer layer 101 and the second outer layer 102, and also includes an intermediate layer 103 inserted between the first outer layer 101 and the second outer layer 102. The contact surface between the first outer layer 101 and the intermediate layer 103 is textured, and the contact surface between the second outer layer 102 and the intermediate layer 103 is also textured. Moreover, the textures of these two contact surfaces are parallel to each other, that is, conformal, which can improve the transparency of viewing the environment on the other side through the transparent projection device body 10.

[0051] The intermediate layer 103 has a different refractive index from the first outer layer 101 and the second outer layer 102. For example, the difference in refractive index between the intermediate layer 103 and at least one of the first outer layer 101 and the second outer layer 102 for a specific wavelength of light (such as 550 nm) can be greater than or equal to 0.3, preferably greater than or equal to 0.5.

[0052] The intermediate layer 103 may include at least one electrolyte layer or metal layer. The intermediate layer 103 may be formed by a stack of layers, which may be formed as a single layer or multiple layers.

[0053] To fabricate the transparent projection device body, a first outer layer 101 with a textured surface can be formed first. Then, an intermediate layer 103 is formed conformally on the textured surface of the first outer layer 101. A second outer layer 102 is then covered on the textured surface of the intermediate layer 103 facing away from the first outer layer 101, such that the side of the second outer layer 102 facing the intermediate layer 103 has a textured surface, while the side facing away from the intermediate layer 103 can be flat. In this way, the contact surfaces between the first outer layer 101 and the intermediate layer 103, as well as the contact surfaces between the second outer layer 102 and the intermediate layer 103, are all textured and parallel to each other. Therefore, for a light beam incident perpendicular to the surface of the first outer layer 101, the optical path length traversed in the intermediate layer 103 is the same. Of course, in an alternative embodiment, a second outer layer 102 with a textured surface can be formed first, and then an intermediate layer 103 can be formed conformally on the textured surface of the second outer layer 102. A first outer layer 101 can then be overlaid on the textured surface of the intermediate layer 103 facing away from the second outer layer 1021, such that the side of the first outer layer 101 facing the intermediate layer 103 has a textured surface, while the surface facing away from the intermediate layer 103 can be planar. The texturing of the contact surfaces between adjacent layers in the two outer layers and the intermediate layer is used to achieve diffuse reflection.

[0054] Both the first outer layer 101 and the first outer layer 102 can be made of polymer materials. Alternatively, one outer layer can be made of glass or ceramic, while the other outer layer can be made of polymer materials.

[0055] At least one of the first outer layers 101 and 102 may consist of a substrate and a structural layer, wherein the substrate provides support for the structural layer and the surface of the structural layer facing away from the substrate forms the textured surface required for the outer layer.

[0056] In this embodiment, to meet the actual needs of projection, the reflection angle of the image light incident on the optimal viewing area through specular reflection from the surface of the transparent projection device is defined. Since the light spot visible to the user in this patent application originates from this reflected light, the antireflection film also needs to be designed and optimized for these reflection angles.

[0057] When the above reflection angle is 10-30 degrees, and when the antireflection film is a single-layer material, the thickness of the antireflection film can be 90-100 nm. Experiments have shown that antireflection films with this thickness range can reduce the overall reflectivity of incident light in the visible light range with this incident angle to a low level.

[0058] When the aforementioned reflection angle is 10-30 degrees, and when the antireflection film is a four-layer material, the thickness of the antireflection film can be 250nm-300nm. Experiments have shown that an antireflection film with this thickness range can reduce the overall reflectivity of incident light in the visible light range with this incident angle to a low level.

[0059] When the aforementioned reflection angle is 10-30 degrees, and when the antireflection film is a six-layer material, the thickness of the antireflection film can be 240nm-350nm. Experiments have shown that an antireflection film with this thickness range can reduce the overall reflectivity of incident light in the visible light range with this incident angle to a low level.

[0060] The table below lists, as an example only, the parameters and reflectivity test results of transparent projection devices using antireflective coatings with various different structures: Table 1

[0061] The scenarios with a reflection angle of 15° are more suited to using long-throw projectors, the scenarios with a reflection angle of 25° are more suited to using short-throw projectors, and the scenarios with a reflection angle of 20° are more suited to a centered solution.

[0062] Simulation results show that applying the single-layer antireflection film scheme shown in Table 1 to transparent projection devices can reduce the reflectivity of reflected light with a reflection angle of 15°-25° to below 1.6%; applying the four-layer antireflection film scheme shown in Table 1 to transparent projection devices can reduce the reflectivity of reflected light with a reflection angle of 15°-25° to below 0.9%; and applying the six-layer antireflection film scheme shown in Table 1 to transparent projection devices can reduce the reflectivity of reflected light with a reflection angle of 15°-25° to below 0.5%. This can significantly alleviate the projector's light spot problem.

[0063] Example 2 Embodiment 2 of this application provides a transparent projection device. The main difference from Embodiment 1 is that the textured structure of the contact surface between two adjacent layers in the two outer layers and the middle layer of the transparent projection device body in this embodiment is a Fresnel textured structure, which can improve the uniformity of the transparent projection device display and reduce the interference of external ambient light on the transparent projection device, thus giving it a better viewing experience.

[0064] like Figure 3 As shown, in this embodiment, the transparent projection device includes a transparent projection device body 100 and an antireflective film 111 disposed on one side of the transparent projection device body. The transparent projection device body 100 includes two outer layers with substantially the same refractive index, hereinafter referred to as the first outer layer 1011 and the second outer layer 1021, and also includes an intermediate layer 1031 inserted between the first outer layer 1011 and the second outer layer 1021. The contact surface between the first outer layer 1011 and the intermediate layer 1031 is textured, and the contact surface between the second outer layer 1021 and the intermediate layer 1031 is also textured. Furthermore, the textures of these two contact surfaces are parallel to each other, i.e., conformal, which improves the transparency of viewing the opposite environment through the transparent projection device body 100. The contact surface between the first outer layer 1011 and the intermediate layer 1031 has Fresnel texture, and the contact surface between the second outer layer 1021 and the intermediate layer 1031 also has Fresnel texture.

[0065] For specific features of Fresnel texturing, please refer to Chinese patent application CN202110629866.9 for the Fresnel texturing features of the contact surface between the Fresnel structure layer and the display layer, and the Fresnel texturing features of the contact surface between the display layer and the refractive index matching layer. These will not be repeated here.

[0066] By selecting the specific texture features described above, the transparent projection device in this embodiment can not only overcome the influence of projector light spots, but also eliminate the influence of ambient light, thereby eliminating the two main defects that affect the viewing experience of transparent projection.

[0067] In another preferred embodiment, the contact surface with Fresnel texture also has a convex-concave microstructure to achieve diffuse reflection, so that the projected imaging surface is located at the intermediate layer position and the viewing angle range is improved.

[0068] Example 3 This application provides a transparent projection device in embodiment three. The main difference from embodiment one is that the transparent projection device in this embodiment has anti-reflection films on both sides of the transparent projection device body facing the projector and facing away from the projector.

[0069] See details as follows Figure 4 As shown, with Figure 1 Components with the same reference numerals are identical components and will not be described further here. In this embodiment, an anti-reflection film 12 is provided on the side of the projection device body 10 facing away from the projector 2.

[0070] By setting the antireflection film 12, the ghosting problem caused by the secondary reflection of incident light from the projector 2 on the surface of the projection device body 10 away from the projector 2 and its re-entry into the human eye can be further reduced. At the same time, the problem of reflected light spots caused by reflection at this side surface can also be further reduced.

[0071] The preferred embodiments of this application have been described in detail above with reference to the accompanying drawings. However, this application is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this application, various simple modifications can be made to the technical solution of this application, and these simple modifications all fall within the protection scope of this application.

[0072] Furthermore, various different implementations of this application can be combined in any way, as long as they do not violate the spirit of this application, they should also be regarded as the content disclosed in this application.

Claims

1. A transparent projection device, comprising a transparent projection device body and an antireflective film disposed on at least one side of the transparent projection device body, wherein image light is incident on the antireflective film and the transparent projection device body at an oblique angle, the antireflective film being used to reduce the intensity of reflected light incident on the optimal viewing area by specular reflection of the image light through the surface of the transparent projection device body at an oblique angle, thereby preventing light spots, and the transparent projection device body reflecting the image light to the optimal viewing area through diffuse reflection.

2. The transparent projection device as described in claim 1, characterized in that, The antireflective film is disposed on the side of the transparent projection device body facing the projector.

3. The transparent projection device as described in claim 1, characterized in that, The antireflective film is disposed on the side of the transparent projection device body facing the projector and the side facing away from the projector.

4. The transparent projection device as described in claim 1, characterized in that, The transparent projection device body includes two outer layers with essentially the same refractive index and an intermediate layer inserted between the two outer layers, wherein the refractive index of the intermediate layer is different from that of the two outer layers.

5. The transparent projection device as described in claim 1, characterized in that, The transparent projection device body includes: the contact surfaces between two adjacent layers in the two outer layers and the middle layer are textured and parallel to each other.

6. The transparent projection device as described in claim 5, characterized in that, Textured surfaces between adjacent layers in the two outer and middle layers are used to achieve diffuse reflection.

7. The transparent projection device as described in claim 5, characterized in that, The contact surfaces between two adjacent layers in the two outer layers and the middle layer have a Fresnel textured structure.

8. The transparent projection device as described in claim 7, characterized in that, The Fresnel textured structure has a diffuse reflection microstructure on the side facing the projector.

9. The transparent projection device as described in claim 4, characterized in that, At least one of the two outer layers is made of a polymer material or a glass material.

10. The transparent projection device as described in claim 5, characterized in that, The intermediate layer is formed by a single layer or by a stack of multiple layers.

11. The transparent projection device as described in claim 2, characterized in that, The reflection angle of the reflected light of the image light incident on the optimal viewing area through mirror reflection of the surface of the transparent projection device is 10-30 degrees.

12. The transparent projection device as claimed in claim 11, characterized in that, When the antireflective coating is a single-layer material, the thickness of the antireflective coating is 90-100 nm.

13. The transparent projection device as claimed in claim 11, characterized in that, When the antireflective coating is a four-layer material, the thickness of the antireflective coating is 250nm-300nm.

14. The transparent projection device as claimed in claim 11, characterized in that, When the antireflective coating is a six-layer material, the thickness of the antireflective coating is 240nm-350nm.

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