Holographic projection device

Abstract

The embodiment of the invention relates to the technical field of projection display. More specifically, the invention relates to a holographic projection device. The holographic projection device comprises an image generation element used for emitting a projection light beam carrying image information; the diffusion element and the holographic element are both located in a light path of the projection light beam, the diffusion element is used for expanding the projection light beam, and the holographic element is used for imaging based on the expanded projection light beam; the light beam adjusting element is located in a light path between the diffusion element and the image generation element and is used for enabling the first light beam to enter and adjusting and emitting the second light beam; the angle expansion amount difference between the light spot center and the edge of the second light beam is smaller than the angle expansion amount difference between the light spot center and the edge of the first light beam. The embodiment of the invention is used for solving the problem that the diffraction efficiency of a holographic element is relatively low, so that images seen by human eyes are not uniform.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of projection display. More specifically, it relates to a holographic projection device. Background Art

[0002] In the prior art, the projection beam emitted by the image generation element reaches the diffusion element after being reflected by the reflection element, and the projection beam after being expanded by the diffusion element reaches the holographic element. The holographic element combines the image carried by the projection beam into the human eye, and the image seen by the human eye is a virtual image formed in the far field.

[0003] However, when the projection beam emitted by the image generation element reaches the diffusion element after being reflected by the reflection element, since the angular spread of the center of the projection beam is smaller than the angular spread of the beam edge, when further expanded by the diffusion element, the angular spread of the beam edge of the projection beam further increases, resulting in the angular spread of the projection beam deviating from the diffraction angle of the holographic element when the projection beam reaches the holographic element, and the deviation degree is relatively large, thereby reducing the diffraction efficiency of the holographic element and causing the image seen by the human eye to be uneven. Summary of the Invention

[0004] The present application provides a holographic projection device for solving the problem that the image seen by the human eye is uneven due to the low diffraction efficiency of the holographic element.

[0005] The technical solutions provided by the present application are as follows:

[0006] The present application provides a holographic projection device, including:

[0007] An image generation element for emitting a projection beam carrying image information;

[0008] A diffusion element and a holographic element, both located in the optical path of the projection beam, the diffusion element is used for expanding the projection beam, and the holographic element is used for imaging based on the expanded projection beam;

[0009] A beam adjustment element, located in the optical path between the diffusion element and the image generation element, for incident a first beam and adjusting an emitted second beam; the difference in the angular spread between the center and the edge of the spot of the second beam is smaller than the difference in the angular spread between the center and the edge of the spot of the first beam.

[0010] It can be seen from the above technical scheme that the holographic projection device provided by the present application, by arranging a beam adjustment element in the optical path between the image generating element and the diffusion element, uses the beam adjustment element to adjust the projection light emitted by the image generating element, so that the difference in the angular expansion amount between the center and the edge of the light spot of the adjusted projection beam, i.e., the second beam, becomes smaller. Then, the second beam is expanded by the diffusion element and enters the holographic element. Since the difference in the angular expansion amount between the center and the edge of the light spot of the second beam becomes smaller, after the second beam is expanded by the diffusion element, the difference in the angular expansion amount between the center and the edge of the light spot of the beam after expansion by the diffusion element can be reduced, which is beneficial to reducing the deviation between the diffusion angle of the projection beam incident on the holographic element and the diffraction angle of the holographic element itself, and further beneficial to improving the diffraction efficiency of the holographic element, and can improve the uniformity of the image seen by the human eye. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the implementation methods in the embodiments of the present application or the related technologies, the following is a brief introduction to the drawings required for use in the embodiments or the related technology descriptions. Obviously, the drawings described below are some embodiments of the present application, and a person skilled in the art can also obtain other drawings based on these drawings.

[0012] Figure 1 It is a structural schematic diagram of a holographic projection device provided in the related art;

[0013] Figure 2 It is a schematic diagram of a partially enlarged structure of a holographic projection device provided in the related art;

[0014] Figure 3 Shows a schematic structural diagram of a holographic projection device provided by some embodiments of the present application;

[0015] Figure 4 Shows a schematic structural diagram of another holographic projection device provided by some embodiments of the present application;

[0016] Figure 5 A schematic diagram of the structure of another holographic projection device provided by some embodiments of the present application is shown;

[0017] Figure 6 A schematic diagram of the structure of another holographic projection device provided by some embodiments of the present application is shown;

[0018] Figure 7 A schematic diagram of the structure of another holographic projection device provided by some embodiments of the present application is shown;

[0019] Figure 8 A schematic diagram of the structure of another holographic projection device provided by some embodiments of the present application is shown;

[0020] Figure 9 Shows a schematic structural diagram of another holographic projection device provided by some embodiments of the present application;

[0021] Figure 10 Shows a schematic structural diagram of another holographic projection device provided by some embodiments of the present application;

[0022] Figure 11 Shows a schematic structural diagram of another holographic projection device provided by some embodiments of the present application;

[0023] Figure 12 Shows a schematic diagram of the change in the diffusion angle of projection light on a diffusion element provided by some embodiments of the present application;

[0024] Figure 13 Shows a schematic diagram of a partially enlarged structure of a first Fresnel lens provided by some embodiments of the present application;

[0025] Figure 14 Shows a schematic diagram of the beam convergence of a first Fresnel lens provided by some embodiments of the present application;

[0026] Figure 15 Shows a schematic diagram of a partially enlarged structure of another first Fresnel lens provided by some embodiments of the present application;

[0027] Figure 16 Shows a schematic structural diagram of another holographic projection device provided by some embodiments of the present application. Detailed implementation manners

[0028] To make the objectives and implementation manners of the present application clearer, the following will clearly and completely describe the exemplary implementation manners of the present application with reference to the accompanying drawings in the exemplary embodiments of the present application. Obviously, the described exemplary embodiments are only a part of the embodiments of the present application, rather than all of the embodiments.

[0029] It should be noted that the brief description of the terms in the present application is only for the convenience of understanding the subsequent described implementation manners, rather than intending to limit the implementation manners of the present application. Unless otherwise specified, these terms should be understood in their ordinary and common meanings.

[0030] The terms "include" and "have" and any variations thereof are intended to cover but not exclusively include. For example, a product or device including a series of components does not necessarily have to be limited to all the clearly listed components, but may include other components that are not clearly listed or are inherent to these products or devices.

[0031] Figure 1 Is a schematic structural diagram of a holographic projection device provided in the related art, Figure 2FIG. 1 is a schematic diagram of a partially enlarged structure of a holographic projection device provided in the related art. Figure 1 and Figure 2 As shown, the holographic projection device includes an image generating element 101, a reflecting element 106, a diffusing element 102 and a holographic element 103. When the projection light beam emitted by the image generating element 101 is reflected by the reflecting element 106 and reaches the diffusing element 102, the projection light beam is expanded by the diffusing element 102 and reaches the holographic element 103. The holographic element 103 is used to bring the image carried by the projection light beam into the human eye, and the image seen by the human eye is a virtual image 104 formed in the far field.

[0032] However, the projection light beam emitted by the image generating element 101 reaches the diffusion element 102 after being reflected by the reflecting element 106. Since the angular expansion amount at the center of the projection light beam is smaller than the angular expansion amount at the edge of the light beam, the angular expansion amount at the edge of the projection light beam is further increased after the projection light beam is further expanded by the diffusion element 102. As a result, when the projection light beam reaches the holographic element 103, the diffusion angle of the projection light beam on the holographic element 103 deviates from the diffraction angle of the holographic element 103 itself, and the diffusion angle of the projection light beam on the holographic element 103 deviates greatly from the diffraction angle of the holographic element 103 itself, thereby reducing the diffraction efficiency of the holographic element 103 and causing the problem of uneven image seen by human eyes.

[0033] In view of the technical problems existing in the related art, the embodiment of the present application provides a holographic projection device. The holographic projection device provided by the embodiment of the present application, by arranging a beam adjustment element in the optical path between the image generating element and the diffusion element, uses the beam adjustment element to adjust the projection light emitted by the image generating element, so that the difference in the angular expansion amount between the center and the edge of the light spot of the adjusted projection beam, i.e., the second beam, becomes smaller, and then the second beam is incident on the holographic element after being expanded by the diffusion element. Since the difference in the angular expansion amount between the center and the edge of the light spot of the second beam becomes smaller, after the second beam is expanded by the diffusion element, the difference in the angular expansion amount between the center and the edge of the light spot of the beam after being expanded by the diffusion element can be reduced, which is beneficial to reducing the deviation between the diffusion angle of the projection beam incident on the holographic element and the diffraction angle of the holographic element itself, thereby facilitating improving the diffraction efficiency of the holographic element, and improving the uniformity of the image seen by the human eye.

[0034] Figure 3 This is a schematic diagram of the structure of a holographic projection device provided in an embodiment of the present application. Figure 3 As shown, the holographic projection device includes: an image generating element 101 , a diffusion element 102 , a holographic element 103 and a beam adjusting element 105 .

[0035] Among them, the image generation element 101 includes an image generation unit (Picture Generation Unit, PGU), which generates a projection beam for carrying image information through the image generation unit and emits the projection beam. Specifically, the image generation element 101 can be disposed in a projector, whereby the projector can emit a projection beam carrying image information.

[0036] Among them, the diffusion element 102 is located in the optical path of the projection beam. The diffusion element 102 is configured to receive the projection beam emitted by the image generation element 101 and expand the received projection beam. Exemplarily, the diffusion element 102 can be set as a diffusion film, and the projection beam is received through the diffusion film to achieve beam expansion of the projection beam; the diffusion element 102 can also be set as a diffusion wheel formed by a rotating diffusion sheet, and the projection beam on the beam transmission path can be expanded through rotation diffusion. In some embodiments, the diffusion element 102 can also be set as other specific elements that can achieve beam expansion of the projection beam, which is not limited in the embodiments of the present application.

[0037] Among them, the holographic element 103 is located in the optical path of the projection beam. The holographic element 103 is specifically configured to receive the projection beam expanded by the diffusion element 102, form an image according to the expanded projection beam, and merge the image into the human eye. The image seen by the human eye is a virtual image 104 formed in the far field.

[0038] Among them, the beam adjustment element 105 is located in the optical path of the projection beam, and is configured to receive the incident beam, that is, the first beam, and adjust the first beam to emit a second beam, so as to adjust the difference in the angular spread between the center and the edge of the spot of the projection beam corresponding to the beam. The specific adjustment result is that the difference in the angular spread between the center and the edge of the spot of the second beam is smaller than the difference in the angular spread between the center and the edge of the spot of the first beam.

[0039] In some embodiments, the beam adjustment element 105 can be disposed between the image generation element 101 and the diffusion element 102. Exemplarily, as Figure 3 shown, the beam adjustment element 105 is disposed between the image generation element 101 and the diffusion element 102. Specifically, the projection beam emitted by the image generation element 101 passes through the beam adjustment element 105. The beam adjustment element 105 is configured to receive the incident beam, that is, the first beam, and adjust the first beam. After adjustment, an outgoing beam, that is, the second beam, is formed. Among them, after the first beam is adjusted by the beam adjustment element 105, it can be realized that the difference in the angular spread between the center and the edge of the spot of the second beam is smaller than the difference in the angular spread between the center and the edge of the spot of the first beam.

[0040] It should be noted that when the projection beam emitted by the image generation element 101 reaches the holographic element 103 through the beam transmission path, the projection beam has a corresponding target divergence angle at the target edge position of the holographic element 103, and the holographic element 103 itself has a preset diffraction angle. Based on this, in the embodiment of the present application, after the projection beam emitted by the image generation element 101 is adjusted by the beam adjustment element 105, it is then expanded by the diffusion element 102 onto the holographic element 103, which can reduce the difference between the target divergence angle of the projection beam on the holographic element 103 and the preset diffraction angle of the holographic element 103 itself. Exemplarily, by setting a preset difference threshold, the difference between the target divergence angle and the preset diffraction angle can be made less than the preset difference threshold, which is beneficial to improving the diffraction efficiency of the holographic element 103 and can improve the uniformity of the image seen by the human eye.

[0041] Thus, by setting the beam adjustment element 105, it is possible to adjust the projection beam before the diffusion element 102 diffuses the projection beam, so that the difference in the angular spread between the center and the edge of the spot of the adjusted projection beam, i.e., the second beam, becomes smaller. Then, after the second beam is expanded by the diffusion element 102 and incident on the holographic element 103, since the difference in the angular spread between the center and the edge of the spot of the second beam becomes smaller, after the second beam is expanded by the diffusion element 102, the difference in the angular spread between the center and the edge of the beam expanded by the diffusion element 102 can be reduced, which is beneficial to reducing the deviation between the target divergence angle of the projection beam incident on the holographic element 103 and the preset diffraction angle of the holographic element 103 itself, and further beneficial to improving the diffraction efficiency of the holographic element 103 and can improve the uniformity of the image seen by the human eye.

[0042] In the prior art, as Figure 1 and Figure 2 shown, when the projection beam emitted by the image generation element 101 directly reaches the diffusion element 102 after being reflected by the reflection element 106, since the angular spread of the center of the projection beam emitted by the image generation element 101 is smaller than the angular spread of the beam edge, when further expanded by the diffusion element 102, the angular spread of the beam edge is further increased. As a result, when the projection beam is expanded by the diffusion element 102 and incident on the holographic element 103, the target divergence angle of the projection beam on the holographic element 103 deviates far from the preset diffraction angle of the holographic element 103 itself, thereby reducing the diffraction efficiency of the holographic element 103. Compared with the prior art, the embodiment of the present application is beneficial to improving the diffraction efficiency of the holographic element 103 and can improve the uniformity of the image seen by the human eye by adjusting the projection beam before the diffusion element 102 diffuses the projection beam.

[0043] It should be noted that, Figure 3Only exemplary shows that the beam adjustment element 105 is arranged between the image generation element 101 and the diffusion element 102. The beam adjustment element 105 and the diffusion element 102 can also be integrally arranged. For example, the beam adjustment element 105 is integrally arranged on the light beam incident surface of the diffusion element 102.

[0044] Exemplarily, Figure 4 is a schematic structural diagram of another holographic projection device provided by an embodiment of the present application. As Figure 4 shown, the beam adjustment element 105 is integrally arranged on the light beam incident surface of the diffusion element 102. Thus, by integrally arranging the beam adjustment element 105 on the diffusion element 102, when the projection light beam emitted by the image generation element 101 is incident on the diffusion element 102, the projection light beam can be adjusted and expanded. By integrally arranging the beam adjustment element 105 and the diffusion element 102, it is beneficial to realize the miniaturization setting of the holographic projection device.

[0045] Exemplarily, Figure 5 is a schematic structural diagram of another holographic projection device provided by an embodiment of the present application. As Figure 5 shown, the beam adjustment element 105 is integrally arranged on the light beam exit surface of the diffusion element 102. Thus, by integrally arranging the beam adjustment element 105 on the diffusion element 102, when the projection light beam emitted by the image generation element 101 is incident on the diffusion element 102, the projection light beam can be adjusted and expanded.

[0046] Exemplarily, Figure 6 is a schematic structural diagram of another holographic projection device provided by an embodiment of the present application. As Figure 6 shown, two beam adjustment elements 105 can be arranged. One beam adjustment element 105 is integrally arranged on the light beam incident surface of the diffusion element 102, and the other beam adjustment element 105 is integrally arranged on the light beam exit surface of the diffusion element 102. Thus, by integrally arranging the beam adjustment element 105 on the diffusion element 102, when the projection light beam emitted by the image generation element 101 is incident on the diffusion element 102, the projection light beam can be adjusted and expanded.

[0047] In addition, by integrally arranging two beam adjustment elements 105 on the diffusion element 102, when the projection light beam expanded by the diffusion element 102 is incident on the holographic element 103, the approximation degree between the target diffusion angle of the projection light beam on the holographic element 103 and the preset diffraction angle of the holographic element 103 is further improved, thereby further improving the diffraction efficiency of the holographic element 103.

[0048] The holographic projection device provided by the embodiment of the present application adjusts the projection light beam emitted by the image generation element 101 by arranging a beam adjustment element 105 in the optical path between the image generation element 101 and the diffusion element 102, so that the difference in the angular spread between the center and the edge of the spot of the adjusted projection beam, that is, the second beam, becomes smaller. Then, after the second beam is expanded by the diffusion element 102 and enters the holographic element 103, since the difference in the angular spread between the center and the edge of the spot of the second beam becomes smaller, after the second beam is expanded by the diffusion element 102, the difference in the angular spread between the center and the edge of the beam expanded by the diffusion element 102 can be reduced, which is beneficial to reducing the deviation between the diffusion angle of the projection beam incident on the holographic element 103 and the diffraction angle of the holographic element 103 itself, and further beneficial to improving the diffraction efficiency of the holographic element 103 and improving the uniformity of the image seen by the human eye.

[0049] In some embodiments, a reflection element may also be provided in the holographic projection device. Exemplarily, Figure 7 is a schematic structural diagram of another holographic projection device provided by the embodiment of the present application. Specifically, as Figure 7 shown, a reflection element 106 is arranged between the image generation element 101 and the beam adjustment element 105, and the projection beam emitted by the image generation element 101 is incident on the reflection element 106, and the projection beam is reflected to the beam adjustment element 105 by the reflection element 106.

[0050] Thus, by arranging the reflection element 106 between the image generation element 101 and the beam adjustment element 105, the projection beam emitted by the image generation element 101 can be reflected to the beam adjustment element 105 by the reflection element 106. Among them, the use of the reflection element 106 can realize the turning of the projection beam emitted by the image generation element 101, which is beneficial to shortening the transmission path of the projection beam, and thus beneficial to realizing the miniaturized setting of the holographic projection device.

[0051] Exemplarily, the reflection element 106 can be specifically set as a reflecting mirror, and the projection beam emitted by the image generation element 101 can be reflected to the beam adjustment element 105 through the reflecting mirror. In some embodiments, the reflection element 106 can also be set as other specific elements that can reflect the projection light, and the embodiment of the present application is not limited thereto.

[0052] In some embodiments, Figure 8 is a schematic structural diagram of another holographic projection device provided by the embodiment of the present application. As Figure 8As shown, a reflection element 106 is disposed between the light beam adjustment element 105 and the diffusion element 102. The projection light beam emitted by the image generation element 101 is incident on the light beam adjustment element 105. After the light beam adjustment element 105 adjusts the projection light beam, the adjusted projection light beam is reflected by the reflection element 106 onto the diffusion element 102.

[0053] Thus, by disposing the reflection element 106 between the light beam adjustment element 105 and the diffusion element 102, the projection light beam adjusted by the light beam adjustment element 105 is reflected onto the diffusion element 102. The reflection element 106 can be used to turn the projection light beam, which is beneficial to shortening the light beam projection transmission path, and thus beneficial to realizing the miniaturization setting of the holographic projection device.

[0054] In some embodiments, Figure 9 is a schematic structural diagram of another holographic projection device provided by an embodiment of the present application. As Figure 9 shown, when the light beam adjustment element 105 is integrally disposed on the light beam incident surface of the diffusion element 102, the reflection element 106 can be disposed between the light beam incident surface of the diffusion element 102 and the image generation element 101. Specifically, the projection light beam emitted by the image generation element 101 can be reflected by the reflection element 106 onto the light beam adjustment element 105 on the light beam incident surface, and the projection light passes through the light beam adjustment element 105 and then is incident on the diffusion element 102.

[0055] In some embodiments, Figure 10 is a schematic structural diagram of another holographic projection device provided by an embodiment of the present application. As Figure 10 shown, two light beam adjustment elements 105 can be provided. One light beam adjustment element 105 is disposed between the image generation element 101 and the reflection element 106, and the other light beam adjustment element 105 is disposed between the reflection element 106 and the diffusion element 102. Specifically, the projection light beam emitted by the image generation element 101 is adjusted by one light beam adjustment element 105, and the adjusted projection light beam is reflected by the reflection element 106 onto the other light beam adjustment element 105 for re-adjustment. The re-adjusted projection light beam is incident on the diffusion element 102 through the projection light beam transmission optical path.

[0056] Thus, by providing two light beam adjustment elements 105, it is beneficial to reduce the target diffusion angle when the adjusted projection light beam reaches the holographic element 103 after being expanded by the diffusion element 102, so that the target diffusion angle when the adjusted projection light beam reaches the holographic element 103 is close to the preset diffraction angle of the holographic element 103, which is beneficial to improving the diffraction efficiency of the holographic element 103 and can improve the uniformity of the image picture seen by the human eye.

[0057] In addition, by combining two beam adjustment elements, while improving the diffraction efficiency of the holographic element 103, the use of the reflection element 106 can achieve the steering of the projection beam, which is beneficial to shortening the transmission path of the projection beam, and thus beneficial to the miniaturization of the holographic projection device.

[0058] It should be noted that Figures 1 to 10 only an exemplary schematic diagram of the projection optical path of the holographic projection device is shown, which does not constitute a limitation on the distance of the beam transmission path between the components in the holographic projection device, nor does it constitute a limitation on the specific positions between the components.

[0059] In some embodiments, with reference to Figures 3 to 10 any of the figures shown, the beam adjustment element 105 can be set as the first Fresnel lens, and the holographic element 103 can be set as the second Fresnel lens.

[0060] Exemplarily, Figure 11 is a schematic structural diagram of another holographic projection device provided by an embodiment of the present application. As Figure 11 shown, the beam adjustment element 105 is set as the first Fresnel lens 0105, and the holographic element 103 is set as the second Fresnel lens 0103.

[0061] Among them, the focal length of the first Fresnel lens 0105 is less than the focal length of the second Fresnel lens 0103. Exemplarily, the focal length of the first Fresnel lens 0105 can be set to 80 mm to 150 mm, and the focal length of the second Fresnel lens 0103 can be set to 250 mm to 450 mm. With such a setting, it can be realized that after the projection beam emitted by the image generation element 101 is adjusted by the beam adjustment element 105, the adjusted projection beam is expanded by the diffusion element 102 and then incident on the holographic element 103, and the holographic element 103 receives the incident projection light and forms an image, which is beneficial to improving the picture display effect.

[0062] Exemplarily, Figure 12 is a schematic diagram of the change in the diffusion angle of the projection light on the diffusion element provided by an embodiment of the present application. As Figure 12 shown, the beam diffusion angle at the upper edge of the diffusion element 102 is small, and the beam diffusion angle at the center of the diffusion element 102 is large.

[0063] Among them, the first Fresnel lens 0105 can be set to have a microstructure with a circular ring distribution or a semi-circular ring distribution. Exemplarily, Figure 13 is a partial enlarged structural schematic diagram of a first Fresnel lens provided by an embodiment of the present application. As Figure 13As shown, the first Fresnel lens 0105 has a micro-structure 1051 with an annular distribution. When a projection beam is incident on the first Fresnel lens 0105, the micro-structure 1051 with an annular distribution on the first Fresnel lens 0105 is used to converge the projection beam.

[0064] Among them, the converging ability of the edge of the micro-structure 1051 with an annular distribution to the projection light is different from that of the center of the micro-structure 1051 with an annular distribution. Specifically, the converging ability of the edge of the micro-structure 1051 with an annular distribution to the projection beam is greater than that of the center of the micro-structure 1051 with an annular distribution to the projection beam.

[0065] Exemplarily, Figure 14 is a schematic diagram of the beam convergence of a first Fresnel lens provided by an embodiment of the present application. As Figure 14 shown, when the first Fresnel lens 0105 converges the incident projection beam, the converging ability of the edge of the first Fresnel lens 0105 is higher than that of the center of the first Fresnel lens 0105.

[0066] Thus, after being adjusted by the beam adjustment element 105, it can be realized that the difference in the angular spread between the center and the edge of the spot of the outgoing beam is less than the difference in the angular spread between the center and the edge of the spot of the incident beam, that is, the difference in the angular spread between the center and the edge of the spot of the second beam is less than the difference in the angular spread between the center and the edge of the spot of the first beam.

[0067] Exemplarily, Figure 15 is a schematic diagram of a partially enlarged structure of another first Fresnel lens provided by an embodiment of the present application. As Figure 15 shown, the first Fresnel lens 0105 has a semi-annularly distributed micro-structure 1052. When a projection beam is incident on the first Fresnel lens 0105, the semi-annularly distributed micro-structure 1052 is used to converge the projection beam.

[0068] Among them, the converging ability of the edge of the micro-structure 1052 with a semi-annular distribution to the projection light is different from that of the center of the micro-structure 1052 with a semi-annular distribution. Specifically, the converging ability of the edge of the micro-structure 1052 with a semi-annular distribution to the projection beam is greater than that of the center of the micro-structure 1052 with a semi-annular distribution to the projection beam.

[0069] Thus, after being adjusted by the beam adjustment element 105, it can be realized that the difference in the angular spread between the center and the edge of the spot of the outgoing beam is less than the difference in the angular spread between the center and the edge of the spot of the incident beam, that is, the difference in the angular spread between the center and the edge of the spot of the second beam is less than the difference in the angular spread between the center and the edge of the spot of the first beam.

[0070] In some embodiments, the second Fresnel lens may be set as a holographic film sheet, or may also be set as a grating, as long as the holographic element 103 can form an image after receiving the projection light beam expanded by the diffusion element 102. The embodiments of the present application are not limited thereto.

[0071] Among them, while the holographic film sheet realizes image display, the human eye can see the virtual image 104 behind through the holographic film sheet. Among them, the grating is a thin sheet composed of strip-shaped lenses, and the thin sheet converges the image carried by the projection light beam into the human eye.

[0072] In some embodiments, Figure 16 FIG. is a schematic structural diagram of another holographic projection device provided by an embodiment of the present application. The image generation element 101 has a lens structure 107. Among them, the optical axes of the lens structure 107, the light beam adjustment element 105, and the holographic element 103 are coaxial.

[0073] When the center of the image carried by the projection light beam is in the central area of the light beam adjustment element 105, and when the center of the image carried by the projection light beam is also in the central area of the holographic element 103, after the projection light beam emitted by the image generation element 101 is adjusted by the light beam adjustment element 105, the angular expansion amount of the edge of the adjusted light beam can be reduced.

[0074] When the center of the image carried by the projection light beam is located on one side of the above-mentioned coaxial optical axis, after the projection light beam emitted by the image generation element 101 is adjusted by the light beam adjustment element 105, the angular expansion amount of the center of the adjusted light beam can be reduced, and the angular expansion amount of the edge of the adjusted light beam can also be reduced.

[0075] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

[0076] For the sake of convenience of explanation, the above description has been made in combination with specific embodiments. However, the above exemplary discussion is not intended to be exhaustive or to limit the embodiments to the specific forms disclosed above. According to the above teachings, various modifications and variations can be obtained. The selection and description of the above embodiments are for the purpose of better explaining the principles and practical applications, so that those skilled in the art can better use the embodiments and various different modified embodiments suitable for specific use considerations.

Claims

1. A holographic projection device, characterized in that, Comprising: An image generation element for emitting a projection beam carrying image information; A diffusion element and a holographic element, both located in the optical path of the projection beam, the diffusion element being used to expand the projection beam, and the holographic element being used to image based on the expanded projection beam; A beam adjustment element located in the optical path between the diffusion element and the image generation element, for incident first beam and adjusting the outgoing second beam; the difference in the angular spread between the center and the edge of the spot of the second beam is less than the difference in the angular spread between the center and the edge of the spot of the first beam.

2. The holographic projection device according to claim 1, wherein The holographic element has a preset diffraction angle; The projection beam has a target diffusion angle at the target edge position of the holographic element; The difference between the target diffusion angle and the preset diffraction angle is less than a preset difference threshold.

3. The holographic projection device according to claim 1, wherein The beam adjustment element is located on the light beam incident surface of the diffusion element; And / or, the beam adjustment element is located on the light beam outgoing surface of the diffusion element.

4. The holographic projection device according to claim 1, wherein, Further comprising: A reflection element located in the optical path between the image generation element and the diffusion element, for reflecting the projection beam; The reflected projection beam is incident on the diffusion element; Wherein, the beam adjustment element is located in the optical path between the image generation element and the reflection element, and / or the beam adjustment element is located in the optical path between the reflection element and the diffusion element.

5. The holographic projection device according to claim 1, wherein The beam adjustment element includes a first Fresnel lens, and the holographic element includes a second Fresnel lens; The focal length of the second Fresnel lens is greater than the focal length of the first Fresnel lens.

6. The holographic projection device according to claim 5, wherein, The first Fresnel lens has a microstructure with a circular ring distribution or a semi-circular ring distribution, for converging the projection beam, and the converging ability at the edge is higher than that at the center.

7. The holographic projection device according to claim 5, characterized in that, The second Fresnel lens includes a holographic film or a grating.

8. The holographic projection device according to claim 5, characterized in that, The focal length of the first Fresnel lens is 80 mm to 150 mm; The focal length of the second Fresnel lens is 250 mm to 450 mm.

9. The holographic projection device according to claim 1, wherein The image generation element has a lens structure, and the optical axes of the lens structure, the beam adjustment element, and the holographic element are all coaxial; The center of the image carried by the projection beam is in the central region of the beam adjustment element and in the central region of the holographic element.

10. The holographic projection device according to claim 1, characterized in that, The image generation element has a lens structure, and the optical axes of the lens structure, the beam adjustment element, and the holographic element are all coaxial; The center of the image carried by the projection beam is located on one side of the optical axis.

Images