Holographic projection device

Abstract

To provide a holographic projection device.SOLUTION: A holographic projection device includes a display assembly and a reflective assembly. The display assembly has a display surface with a horizontal viewing angle and a vertical viewing angle. The display assembly can generate collimated image light meeting a condition 1 or 2. In the condition 1, full widths at half maximum of the collimated image light at the horizontal viewing angle and the vertical viewing angle are less than or equal to 35°. In the condition 2, the luminance of the collimated image light within a range of the full widths at half maximum larger than or equal to 45° are less than or equal to 2% of the maximum luminance of the collimated image light. The reflective assembly is disposed on a transmission path of the collimated image light, and includes a light-transmitting substrate and multiple reflective elements. The light-transmitting substrate is inclined relative to the display surface. The reflective elements are disposed on the light-transmitting substrate and can reflect the collimated image light to a projection position.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to projection devices, in particular holographic projection devices. [Background technology]

[0002] Holographic projection technology can project a three-dimensional image into the air, creating the effect that the three-dimensional image is floating in the air. In addition, special effects such as rotation, movement, and zooming can be added to the three-dimensional image according to actual needs, and visual effects can also be added. Therefore, holographic projection technology is suitable for use in product displays, entertainment shows, etc. However, the three-dimensional images projected by conventional holographic projection devices are usually accompanied by noise images, which often appear on both sides of the three-dimensional image, affecting the viewing experience. Summary of the Invention

[0003] The present invention provides a holographic projection device to improve the problem of noise images.

[0004] In order to achieve some or all of the above objects or other objects, the present invention provides a holographic projection device, comprising a display assembly and a reflecting assembly. The display assembly has a display surface, and the display surface has a horizontal viewing angle and a vertical viewing angle. The display assembly can generate a collimated image beam that satisfies condition 1 or condition 2. Condition 1: The collimated image beam has a first full width at half maximum at a horizontal viewing angle ≦35°, and a second full width at half maximum at a vertical viewing angle ≦35°. Condition 2: The collimated image beam has a first luminance in a range of the first full width at half maximum ≧45°, and a second luminance in a range of the second full width at half maximum ≧45°. The first luminance and the second luminance are each ≦2% of the maximum luminance of the collimated image beam. The reflecting assembly is disposed on a transmission path of the collimated image beam. The reflecting assembly includes a light-transmitting substrate and a plurality of reflecting elements. The light-transmitting substrate is inclined with respect to the display surface. The reflective element is disposed on the light-transmitting substrate and is capable of reflecting the collimated image beam to a projection location.

[0005] In one embodiment of the present invention, the display assembly includes a light source module, a collimation module, and a display panel. The light source module is disposed facing the display panel, and the collimation module is disposed between the light source module and the display panel. The display surface is disposed on the side of the display panel facing away from the collimation module. The collimation module converts the light generated by the light source module into a collimated light, and the display panel converts the collimated light into a collimated image light.

[0006] In one embodiment of the present invention, the light source module includes a plurality of light emitting elements, and the collimation module includes a plurality of collimating lenses, each collimating lens being disposed opposite a corresponding light emitting element.

[0007] In one embodiment of the present invention, each of the light emitting elements has a top surface, and the top surface is disposed facing the collimating lens, and the top surface is disposed at a distance from the collimating lens, for example, the distance being 50 mm or less.

[0008] In one embodiment of the present invention, the display assembly includes a light source module, a light guide plate, an inverse prism sheet, and a display panel. The light guide plate has a light input surface and a light output surface that are connected together. The light source module faces the light input surface, and the inverse prism sheet faces the light output surface. The display panel is installed on a side facing away from the light output surface of the inverse prism sheet, and the display surface is installed on a side facing away from the inverse prism sheet of the display panel. The light source module can generate a light beam, and the light guide plate can guide the light beam emitted from the light output surface at an output angle of 55° to 80°.

[0009] In one embodiment of the present invention, the light guide plate further has a bottom surface. The bottom surface faces the light output surface and has a plurality of light scattering microstructures. Each light scattering microstructure has a first surface and a second surface. The first surface and the second surface are connected to the bottom surface. The first surface faces the light input surface side of the light guide plate, and the second surface is disposed away from the light input surface side of the light guide plate. A first included angle is formed between each of the first surfaces and the bottom surface, and a second included angle is formed between each of the second surfaces and the bottom surface. The angle of each of the first included angles is, for example, smaller than the angle of each of the second included angles.

[0010] In one embodiment of the present invention, the inverse prism sheet includes a plate and a number of prism pillars. The prism pillars are located on the surface of the plate facing the light guide plate, and the axis of each prism pillar extends along the surface. Each prism pillar has an apex angle on the side facing away from the plate, and the angle of each apex angle is, for example, between 60° and 75°.

[0011] In one embodiment of the present invention, the plate further has a first side and a second side. The first side and the second side are located on opposite sides of the surface and face each other. The first side is closer to the light source module than the second side. Each prism column comprises a triangular column and further has a first base angle and a second base angle connected to the surface. Each first base angle is closer to the first side than each second base angle, and the angle of each first base angle is equal to or greater than the angle of each second base angle.

[0012] In one embodiment of the present invention, the holographic projection device further comprises, for example, a light grating, which is disposed opposite to the display surface and can convert the image light emitted from the display surface into a collimated image light.

[0013] In one embodiment of the invention, the reflecting assembly comprises a dihedral corner reflector array, each of the reflecting elements comprising a plurality of micromirrors arranged on a light-transmitting substrate and capable of reflecting collimated image light beams to a projection location.

[0014] The display assembly employed in the holographic projection device of the present invention can generate a collimated image beam and can generate a collimated image beam that satisfies condition 1 or condition 2. Specifically, the display assembly can reduce the first full width at half maximum and the second full width at half maximum of the collimated image beam to 35° or less, or reduce the first brightness and the second brightness of the collimated image beam to 2% or less of the maximum brightness. Therefore, most of the collimated image beam passing through the reflection assembly can be projected to the projection position by two reflections by the reflection element, and the noise image formed by the first reflection of the reflection element can be reduced. As described above, the holographic projection device of the present invention can effectively improve the problem of the noise image.

[0015] In order to make the above and other objects, features and advantages of the present invention more clearly comprehensible, the following detailed description is given with reference to the accompanying drawings in which: [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic diagram of a holographic projection device in one embodiment of the present invention. [Diagram 2] 2 is a diagram showing the relationship between luminance and viewing angle at horizontal viewing angles of the collimated image light beam in FIG. 1. [Diagram 3] 2 is a diagram showing the relationship between luminance and viewing angle at a vertical viewing angle of the collimated image ray of FIG. 1. [Figure 4] 2 is a schematic diagram of an image formed by the reflecting assembly of FIG. 1; [Diagram 5] 5 is a schematic diagram of the reflective element of FIG. 4 reflecting a light beam to a projection position. [Figure 6] FIG. 2 is a schematic diagram of the display assembly of FIG. 1. [Figure 7] FIG. 2 is a schematic diagram of a display assembly for a holographic projection device in accordance with another embodiment of the present invention. [Figure 8] 8 is a partial enlarged view of the light guide plate of FIG. 7. [Figure 9] FIG. 8 is a partial enlarged view of the reverse prism sheet of FIG. [Figure 10] FIG. 2 is a schematic diagram of a display assembly for a holographic projection device in accordance with another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] FIG. 1 is a schematic diagram of a holographic projection device in an embodiment of the present invention. FIG. 2 is a diagram showing the relationship between the brightness and the viewing angle of the collimated image beam in FIG. 1 at the horizontal viewing angle. FIG. 3 is a diagram showing the relationship between the brightness and the viewing angle of the collimated image beam in FIG. 1 at the vertical viewing angle. First, referring to FIG. 1, a holographic projection device 100 includes a display assembly 110 and a reflection assembly 120. The display assembly 110 includes a display surface 111, and the display surface 111 has a horizontal viewing angle and a vertical viewing angle. The display assembly 110 can generate a collimated image beam IL that satisfies condition 1 or condition 2. Referring to FIG. 2 and FIG. 3 at the same time, condition 1: the collimated image beam IL has a first full width at half maximum FW1≦35° at the horizontal viewing angle and a second full width at half maximum FW2≦35° at the vertical viewing angle. Condition 2: The collimated image light IL has a first luminance B1 in the range of a first full width at half maximum FW1≧45°, and has a second luminance B2 in the range of a second full width at half maximum FW2≧45°. The first luminance B1 and the second luminance B2 are each 2% or less of the maximum luminance (i.e., 100%) of the collimated image light IL. Referring again to FIG. 1, the reflection assembly 120 is disposed on the transmission path of the collimated image light IL. The reflection assembly 120 includes a light-transmitting substrate 121 and a plurality of reflection elements 122. The light-transmitting substrate 121 is inclined with respect to the display surface 111. The reflection element 122 is disposed on the light-transmitting substrate 121, and can reflect the collimated image light IL to a projection position P.

[0018] FIG. 4 is a schematic diagram of an image formed by the reflecting assembly of FIG. 1. FIG. 5 is a schematic diagram of the reflecting element of FIG. 4 reflecting a light beam to a projection position. Referring to FIG. 4 and FIG. 5 at the same time, the reflecting assembly 120 includes a dihedral corner reflector array (DCRA). The reflecting element 122 includes micromirrors M1, M2, M3, and M4 (shown in FIG. 5). The micromirrors M1, M2, M3, and M4 are arranged to stand on a light-transmitting substrate 121, and can reflect a collimated image light beam IL (shown in FIG. 1) to a projection position P. In detail, when a light beam LB emitted from a pixel point PX passes through the reflecting element 122, the light beam LB is reflected by the micromirrors M1 and M2 in order, thereby forming an image I at the projection position P (shown in FIG. 4). That is, the light beam LB is reflected twice when passing through the reflecting element 122 and proceeds to the projection position P.

[0019] It is necessary to explain that in the prior art, some of the light beams LB incident on the reflecting element 122 may be emitted from the reflecting element 122 by primary reflection. For example, some of the light beams LB are reflected by the micromirror M1 and then emitted from the reflecting element 122, but the traveling path of the light beams (not shown) that have been primarily reflected is different from the traveling path of the light beams LB that have been reflected twice, so that the light beams that have been reflected only once are not accurately delivered to the projection position P, and a noise image is formed near the projection position P. However, as shown in FIG. 1, the holographic projection device 100 of this embodiment employs a display assembly 110 that can generate a collimated image light beam IL, so that most of the light beams LB are reflected twice when passing through the reflecting element 122 and then emitted from the reflecting element 122, thereby improving the problem of noise images in the prior art.

[0020] In one embodiment, the included angle IA between light-transmissive substrate 121 and display surface 111 may be approximately 45°, although the invention is not limited thereto. In this regard, light-transmissive substrate 121 in this embodiment has opposing surfaces 1210 and 1211, surface 1210 being positioned away from display assembly 110, and reflective element 122 being positioned to stand on surface 1210. However, in one embodiment, reflective element 122 is positioned to stand on surface 1211 or to stand on surfaces 1210 and 1211.

[0021] 6 is a schematic diagram of the display assembly of FIG. 1. Referring to FIG. 6, the display assembly 110 of this embodiment may include a liquid crystal display assembly, but other embodiments are not limited thereto. In this embodiment, the display assembly 110 includes, for example, a light source module 112, a collimation module 113, and a display panel 114. The light source module 112 is disposed to face the display panel 114, and the collimation module 113 is disposed between the light source module 112 and the display panel 114. The display surface 111 is located on the side of the display panel 114 facing away from the collimation module 113. The collimation module 113 can convert the light beam L1 generated by the light source module 112 into a collimated light beam CL, and the display panel 114 can convert the collimated light beam CL into a collimated image light beam IL. Specifically, the light ray L1 generated by the light source module 112 is, for example, a diverging ray, and the collimation module 113 can convert the light ray L1 into a collimated ray CL that meets the above-mentioned condition 1 or condition 2. Furthermore, the display panel 114 converts the collimated ray CL into a collimated image ray IL, and the collimated image ray IL is emitted from the display surface 111. In this embodiment, the display panel 114 is, for example, a liquid crystal display panel, but the present invention is not limited thereto.

[0022] In this embodiment, the light source module 112 includes a plurality of light emitting elements 1120, and the collimation module 113 includes a plurality of collimating lenses 1130. Each collimating lens 1130 is disposed to face each light emitting element 1120. For example, the light emitting elements 1120 are disposed in an array on a substrate, and the collimating lenses 1130 are also disposed in an array, and each collimating lens 1130 is disposed to face each light emitting element 1120. In this embodiment, each collimating lens 1130 includes a Fresnel lens, but the present invention is not limited thereto. In addition, the light emitting elements 1120 in this embodiment may include a light emitting diode (LED), but other embodiments are not limited thereto. In this embodiment, each light emitting element 1120 has a top surface TS, and each top surface TS faces the collimating lens 1130. There is a gap G between the top surface TS and the collimating lens 1130, and the gap G is, for example, 50 mm or less. This allows the collimating lens 1130 to further improve the collimating effect of the light beam L1.

[0023] Compared with the prior art, the display assembly 110 employed in the holographic projection device 100 of this embodiment can generate a collimated image light beam IL and can generate the collimated image light beam IL that satisfies condition 1 or condition 2. In particular, the display assembly 110 can reduce the first half-peak full width FW1 and the second half-peak full width FW2 of the collimated image light beam IL to 35° or less, or reduce the first brightness B1 and the second brightness B2 of the collimated image light beam IL to 2% or less of the maximum brightness. Therefore, most of the collimated image light beam IL passing through the reflection assembly 120 is projected to the projection position P by being reflected twice by the reflection element 122, and the noise image formed by the first reflection by the reflection assembly 122 can be reduced. As described above, the holographic projection device 100 of this embodiment can effectively improve the problem of the noise image I.

[0024] FIG. 7 is a schematic diagram of a display assembly of a holographic projection device in another embodiment of the present invention. FIG. 8 is a partial enlarged view of the light guide plate in FIG. 7. FIG. 9 is a partial enlarged view of the reverse prism sheet in FIG. 7. The structure and advantages of the holographic projection device 100a in this embodiment are similar to the embodiment in FIG. 1, and only the differences will be described below. First, referring to FIG. 7, the display assembly 110a may include a light source module 112a, a light guide plate 113a, a display panel 114, and a reverse prism sheet 115. The light guide plate 113a has a light input surface IS and a light output surface ES coupled together. The light source module 112a faces the light input surface IS, and the reverse prism sheet 115 faces the light output surface ES. The display panel 114 is disposed on the opposite side of the reverse prism sheet 115 from the light output surface ES, and the display surface 111 is located on the side of the display panel 114 facing away from the reverse prism sheet 115. The light source module 112a generates a light beam LB1, and the light guide plate 113a can guide the light beam LB1 emitted from the light output surface ES at an emission angle A of 55° to 80°. Specifically, the light beam LB1 emitted from the light output surface ES enters the inverse prism sheet 115, which can guide the light beam LB1 to approach a forward emission and convert the multiple light beams LB1 into collimated light beams CL. Similarly, the collimated light beams CL satisfy the above-mentioned condition 1 or condition 2, and the display panel 114 can convert the collimated light beams CL into collimated image light beams IL.

[0025] 7 and 8, the light guide plate 113a further has a bottom surface BS. The bottom surface BS faces the light output surface ES and has a plurality of light scattering microstructures 1130a. Each light scattering microstructure 1130a has a first surface S1 and a second surface S2. The first surface S1 and the second surface S2 are connected to the bottom surface BS. The first surface S1 faces the light input surface IS side of the light guide plate 113a, and the second surface S2 faces away from the light input surface IS side of the light guide plate 113a. A first included angle IA1 (shown in FIG. 8) is formed between each first surface S1 and the bottom surface BS, and a second included angle IA2 (shown in FIG. 8) is formed between each second surface S2 and the bottom surface BS. The angle of each first included angle IA1 is smaller than the angle of each second included angle IA2, for example, so that the first surface S1 can guide the light beam LB1 emitted from the light-emitting surface ES at an emission angle A of 55° to 80°. That is, the gradient of the first surface S1 with respect to the bottom surface BS is smaller than the gradient of the second surface S2 with respect to the bottom surface BS, and most of the light beam LB1 incident on the scattered light microstructure 1130a is reflected by the first surface S1 to the light-emitting surface ES. In one embodiment, the angle of the first included angle IA1 is, for example, in the range of about 15° to 45°, and the angle of the second included angle IA2 is in the range of about 30° to 75°, and the present invention is not limited to specific values.

[0026] 7 and 9, in this embodiment, the inverse prism sheet 115 may include a plate 1150 and a plurality of prism pillars 1151. The prism pillars 1151 are located on a surface S of the plate 1150 facing the light guide plate 113a, and the axial direction D (shown in FIG. 9) of each prism pillar 1151 extends along the surface S. Each prism pillar 1151 has an apex angle TA on the side facing away from the plate 1150, and the angle A0 of each apex angle TA is, for example, in the range of 60° to 75°. This allows the prism pillars 1151 to guide the light beam LB1 to be closer to the forward emission, and the collimation effect of the inverse prism sheet 115 on the light beam LB1 can be further improved. Meanwhile, the plate 1150 further has a first side surface SS1 and a second side surface SS2 (shown in FIG. 7). The first side surface SS1 and the second side surface SS2 are located on opposite sides of the surface S and face each other. The first side surface SS1 is closer to the light source module 112a than the second side surface SS2. Each prism column 1151 includes a triangular column, and each triangular column further has a first base angle BA1 and a second base angle BA2 (shown in FIG. 9) connected to the surface S. Each first base angle BA1 is closer to the first side surface SS1 than each second base angle BA2, and the angle A1 of each first base angle BA1 is equal to or larger than the angle A2 of each second base angle BA2, which can improve the uniformity of the output of the inverted prism sheet 115. For example, in this embodiment, the angle A1 is greater than the angle A2. In one embodiment, the angles A1 and A2 are in the range of about 50° to 70°, but the present invention is not limited to the specific values.

[0027] Continuing to refer to Fig. 7, the characteristics of the light source module 112a of this embodiment are substantially the same as those of the light source module 112 of Fig. 6, and therefore the relevant description will be omitted. In addition, the display assembly 110a further includes a reflective sheet R. The reflective sheet R is disposed opposite the bottom surface BS, and can improve the light utilization rate of the display assembly 110a. The material of the reflective sheet R includes, but is not limited to, silver.

[0028] FIG. 10 is a schematic diagram of a display assembly of a holographic projection device in another embodiment of the present invention. The structure and advantages of the holographic projection device 100b in this embodiment are similar to those in the embodiment of FIG. 1, and only the differences are described below. Referring to FIG. 10, the holographic projection device 100b further includes a light grating 130. The light grating 130 is disposed opposite to the display surface 111, and can convert the light beam L emitted from the display surface 111 into a collimated image light beam IL. In detail, although the light beam L emitted from the display surface 111 does not satisfy the above-mentioned condition 1 or condition 2, the light grating 130 can convert the light beam L into a collimated image light beam IL. In this embodiment, the display assembly 110b includes a liquid crystal display assembly, but other embodiments are not limited thereto. Incidentally, the optical grating 130 includes a light-transmitting portion 131 and a light-shielding portion 132, and the light-transmitting portion 131 has a width W1 on a side facing away from the light-emitting surface ES, and a width W2 on a side facing the light-emitting surface ES. In this embodiment, the width W1 and the width W2 are almost the same, but in one embodiment, the width W1 may be larger than the width W2. That is, in one embodiment, the shape of the light-transmitting portion 131 is a trapezoid. However, the present invention is not limited to the detailed features of the light-transmitting portion 131 and the light-shielding portion 132.

[0029] In summary, the display assembly adopted in the holographic projection device of the present invention can generate a collimated image beam and can generate a collimated image beam that satisfies condition 1 or condition 2. Specifically, the display assembly can reduce the first full width at half maximum and the second full width at half maximum of the collimated image beam to 35° or less, or reduce the first brightness and the second brightness of the collimated image beam to 2% or less of the maximum brightness. Therefore, most of the collimated image beam passing through the reflection assembly can be projected to the projection position by two reflections by the reflection element, and the noise image formed by the primary reflection can be reduced. As a result, the holographic projection device of the present invention can effectively improve the problem of the noise image.

[0030] The present invention has been disclosed above using examples, but the present invention is not limited thereto. Those skilled in the art can make some modifications without departing from the spirit of the present invention. Therefore, the scope of protection of the present invention is limited by the appended claims. [Explanation of symbols]

[0031] 100, 100a, 100b Holographic projection device 110, 110a, 110b Display assembly 111 Display surface 112, 112a Light source module 113 Collimation Module 113a Light guide plate 114 Display Panel 115 Reverse Prism Sheet 120 Reflector Assembly 121 Light-transparent substrate 122 Reflective element 130 Optical Lattice 131 Translucent part 132 Light shielding part 1120 Light emitting element 1130 Collimating Lens 1130a Scattered light fine structure 1150 Plate 1151 Prismatic Pillar 1210, 1211 surface A Output angle A0, A1, A2 angle B1 First brightness B2 Second Brightness BA1 1st base angle BA2 2nd bottom BS bottom CL Collimated beam D-axis direction ES Idemitsu surface FW1 1st FWHM FW2 2nd FWHM G interval I Video IA inclusion angle IA1 1st inclusion angle IA2 2nd inclusion angle IL Collimated image beam IS light incident surface L Ray L1 ray LB light LB1 Luminous flux M1, M2, M3, M4 Micromirrors P projection position PX pixel point R Reflective sheet S surface S1 First Surface S2 Second Surface SS1 1st side SS2 Second Side TA vertical angle TS top surface W1, W2 width

Claims

1. 1. A holographic projection device comprising: a display assembly; and a reflection assembly, The display assembly has a display surface having a horizontal viewing angle and a vertical viewing angle, and is for generating a collimated image beam that satisfies the following conditions 1 and 2: Condition 1 is that the collimated image ray has a first full width at half maximum at the horizontal viewing angle ≦35° and a second full width at half maximum at the vertical viewing angle ≦35°; Condition 2 is that the collimated image light beam has a first luminance in the range of the first full width at half maximum ≧45°, and has a second luminance in the range of the second full width at half maximum ≧45°, and the first luminance and the second luminance are each 2% or less of the maximum luminance of the collimated image light beam; A holographic projection device, characterized in that the reflection assembly comprises: a light-transmitting substrate disposed on a transmission path of the collimated image light beam and inclined with respect to the display surface; and a reflection assembly disposed on the light-transmitting substrate and having a plurality of reflection elements for reflecting the collimated image light beam to a projection position.

2. 2. The holographic projection device of claim 1, wherein the display assembly comprises a light source module, a collimation module, and a display panel, the light source module is disposed opposite the display panel, and the collimation module is disposed between the light source module and the display panel, the display surface is located on the side of the collimation module behind the display panel, the collimation module converts the light beam generated from the light source module into a collimated light beam, and the display panel converts the collimated light beam into the collimated image light beam.

3. 3. The holographic projection device of claim 2, wherein the light source module comprises a plurality of light-emitting elements, and the collimation module comprises a plurality of collimating lenses, each of the plurality of collimating lenses being arranged to face each of the plurality of light-emitting elements.

4. 4. The holographic projection device of claim 3, wherein each of the light-emitting elements has a top surface, each of the top surfaces faces toward each of the collimating lenses, and the distance between each of the top surfaces and each of the collimating lenses is 50 mm or less.

5. 2. The holographic projection device of claim 1, wherein the display assembly comprises a light source module, a light guide plate, an inverted prism sheet, and a display panel, the light guide plate having a connected light entrance surface and a light exit surface, the light source module faces the light entrance surface, the inverted prism sheet faces the light exit surface, the display panel is disposed on the back side of the inverted prism sheet on the side of the light exit surface, and the display surface is located on the back side of the display panel on the side of the inverted prism sheet, the light source module generates a light beam, and the light guide plate guides the light beam emitted from the light exit surface at an exit angle of 55° to 80°.

6. 6. The holographic projection device of claim 5, wherein the light guide plate further has a bottom surface facing the light output surface and having a plurality of scattered light microstructures, each of the plurality of scattered light microstructures having a plurality of first surfaces and a plurality of second surfaces, the plurality of first surfaces and the plurality of second surfaces being connected to the bottom surface, the plurality of first surfaces facing a front writing surface side of the light guide plate, and the plurality of second surfaces facing a rear side of the front writing surface side of the light guide plate, there are a plurality of first included angles between each of the plurality of first surfaces and the bottom surface, and there are a plurality of second included angles between each of the plurality of second surfaces and the bottom surface, and an angle of each of the plurality of first included angles is smaller than an angle of each of the plurality of second included angles.

7. 6. The holographic projection device of claim 5, wherein the inverse prism sheet has a plate and a plurality of prism pillars, the plurality of prism pillars are located on a surface of the plate facing the light guide plate, and the axial direction of each of the plurality of prism pillars extends along the surface, and each of the plurality of prism pillars has a plurality of apex angles on the back side of the plate, and the angle of each of the plurality of apex angles is between 60° and 75°.

8. The holographic projection device of claim 7, wherein the plate further has a first side and a second side, the first side and the second side being located on opposite sides of the surface and facing each other, the first side being closer to the light source module than the second side, each of the plurality of prism columns comprising a triangular column, further having a plurality of first base angles and a plurality of second base angles connected to the surface, each of the plurality of first base angles being closer to the first side than each of the plurality of second base angles, and the angle of each of the plurality of first base angles being greater than or equal to the angle of each of the plurality of second base angles.

9. 2. The holographic projection device of claim 1, further comprising a light grating disposed opposite the display surface for converting an image beam emitted from the display surface into the collimated image beam.

10. 2. The holographic projection device of claim 1, wherein the reflection assembly comprises a two-sided corner reflector array, the plurality of reflection elements being each arranged to stand on the optically transparent substrate and each comprising a plurality of micromirrors for reflecting the collimated image beam to the projection position.

Images