Backlight module and AR device

Abstract

The present invention discloses a backlight module and an AR device. The backlight module applied to the AR device includes a light source and a light guide component for forming an illumination light path. The light source is used to emit a first light beam carrying image information. The light guide component is used to homogenize the first light beam and also export the first light beam to an imaging component of the AR device. The light guide component includes a light guide block. The light guide block has a first transmission surface and a second reflection surface that are relatively arranged, and a first reflection surface and a second transmission surface that are relatively arranged. The first transmission surface is arranged with a plurality of first homogenization structures, the first reflection surface is arranged with a plurality of second homogenization structures, and the second transmission surface is arranged with a brightening module. Thus, through the arrangement of the light guide component, the architecture of the illumination light path of the AR device is changed, the use of collimating mirrors and relay lenses is reduced, the length of the illumination light path is shortened, and the volume of the AR device is reduced.

Description

Technical Field

[0001] The present invention relates to the field of AR technology, and in particular to a backlight module and an AR device. Background Art

[0002] Head-mounted displays for augmented reality use near-eye display technology, which allows people to view the virtual images being projected while viewing the surrounding environment. The virtual images are superimposed on the real world perceived by the user, which can create a more realistic experience and a stronger sense of immersion for the user. This technology superimposes virtual images on the real world perceived by the user, which can create a realistic experience and has great application prospects in military, security, industry, and medical fields.

[0003] In recent years, augmented reality (AR) technology has developed rapidly, and a series of related commercial products have been released. In order to realize the function of augmented reality, researchers have proposed a variety of solutions, such as Birdbath, prism, free-form surface, optical waveguide and other technologies. In the first three solutions, there is often a contradiction between good product form and better display effect, while optical waveguide can effectively solve the above problems. Therefore, the solution of optical machine plus optical waveguide is an important AR development direction in the future.

[0004] However, the problem is that in the optical waveguide technology solution, since an optical engine, i.e., an optical machine, is required as an image generating unit, the volume tends to be large, and miniaturization is difficult to achieve. Although generally speaking, optical waveguides can be made thinner and lighter, and their shape is close to the size and shape of myopic glasses; however, except for the microLED solution, which can achieve a volume of less than 0.2cc in small and medium fields of view, the optical machines of other solutions are all above 1cc, especially those with a FOV of more than 50 degrees. As the field of view increases, the volume is 1.5cc or even more than 2cc. Summary of the invention

[0005] The present invention provides a backlight module and an AR device, so as to realize the miniaturization of the AR device.

[0006] To achieve the above object, an embodiment of the present invention provides a backlight module, which is applied to an AR device. The backlight module includes: a light source and a light guide component for forming an illumination light path, the light source is used to emit a first light beam carrying image information, and the light guide component is used to homogenize the first light beam and guide the first light beam to an imaging component of the AR device;

[0007] The light guide assembly includes a light guide block, the light guide block has the first transmission surface and the second reflection surface arranged opposite to each other, and the first reflection surface and the second transmission surface arranged opposite to each other, the first transmission surface is arranged with a plurality of first light homogenizing structures, the first reflection surface is arranged with a plurality of second light homogenizing structures, and the second transmission surface is arranged with a brightness enhancement module;

[0008] Among them, the first light homogenizing structure is located outside the light guide block and is arranged adjacent to the light source, and is used to couple the first light beam into the light guide block and homogenize the first light beam; the second light homogenizing structure is located in the light guide block, and is used to reflect and homogenize the light beam incident on the second light homogenizing structure; the brightening module is arranged adjacent to the imaging component, and is used to export the light beam received by the second transmission surface to the imaging component.

[0009] Optionally, the light guide block is a rectangular parallelepiped, and the first light beam can pass through the first light uniforming structure, the first transmission surface, the second light uniforming structure, the second reflection surface, the second transmission surface and the brightness enhancement module in sequence, and then be emitted from the light guide component, and the optical axis of the light beam emitted from the light guide component is perpendicular to the plane where the second transmission surface is located.

[0010] Optionally, the first light homogenizing structure is a pyramid microstructure, and in the direction in which the first transmission surface points to the second reflection surface, the first light homogenizing structure has a first bottom surface and a second bottom surface in sequence, the first bottom surface is away from the first transmission surface, the second bottom surface is attached to the first transmission surface, and the area of ​​the first bottom surface is smaller than the area of ​​the second bottom surface;

[0011] The ratio of the area of ​​the second bottom surface to the area of ​​the first transmission surface is in the range of 1:5 to 1:15; and the bottom angle of the pyramid microstructure is in the range of 45° to 90°.

[0012] Optionally, the pyramid microstructure is a quadrangular pyramid microstructure.

[0013] Optionally, the second light homogenizing structure is a spherical microstructure, and in the direction in which the first reflective surface points to the second transmissive surface, the second light homogenizing structure sequentially has a third bottom surface and a spherical surface, the third bottom surface is in contact with the first reflective surface, and the spherical surface is located in the light guide block and is arranged away from the first reflective surface;

[0014] The ratio of the area of ​​the third bottom surface to the area of ​​the first reflecting surface is in the range of 1:5 to 1:15, and the ratio of the spherical radius to the vector height of the spherical microstructure is in the range of 1 to 2.

[0015] Optionally, the bottom surface of the spherical microstructure is convex in a direction from the first reflective surface to the second transmissive surface, or the spherical microstructure is a hollow structure.

[0016] Optionally, a reflective layer is further provided on the spherical surface of the spherical microstructure.

[0017] Optionally, the brightness enhancement module comprises a first brightness enhancement film and a second brightness enhancement film arranged in a direction from the first reflective surface to the second transmissive surface;

[0018] The first brightness enhancement film is attached to the second transmission surface, and there is a gap between the first brightness enhancement film and the second brightness enhancement film; the extension direction of the third microstructure on the first brightness enhancement film is perpendicular to the extension direction of the fourth microstructure on the second brightness enhancement film.

[0019] Optionally, the third microstructure and the fourth microstructure are triangular prism structures, the cross-sectional triangular base angle of the triangular prism structure ranges from 40° to 50°, and the ratio of the side length of the bottom side of the triangular prism structure to the side length of the light guide block parallel to the bottom side of the triangular prism structure ranges from 1:100 to 1:300.

[0020] To achieve the above object, another embodiment of the present invention provides an AR device, comprising the backlight module according to any embodiment of the present invention, and further comprising: an imaging component for forming an imaging light path;

[0021] The imaging assembly comprises: a polarization beam splitter prism, the polarizing element and the imaging lens respectively arranged on two opposite sides of the polarization beam splitter prism, and a polarization module and an LCOS module respectively arranged on the other two opposite sides of the polarization beam splitter prism;

[0022] Among them, the polarizing element is used to polarize the first light beam emitted by the backlight module to form a polarized light beam, the polarization beam splitting prism is used to reflect the polarized light beam to form a second light beam, and transmit it to the LCOS module; the LCOS module reflects the second light beam to form a third light beam, and transmits it to the polarization beam splitting prism; the polarization beam splitting prism is used to transmit the third light beam and transmit it to the polarization module; the polarization module is used to reflect the third light beam to form a fourth light beam and transmit it to the polarization beam splitting prism, the polarization beam splitting prism is used to reflect the fourth light beam to form a fifth light beam and transmit it to the imaging lens, and the imaging lens outputs it to the waveguide of the AR device.

[0023] Optionally, the LCOS module includes a first lens, a second lens and an LCOS chip, and the first lens and the second lens are glued together;

[0024] The optical focal power of the first lens is positive, the optical focal power of the second lens is negative, and the second lens is arranged adjacent to the LCOS chip; at least one surface of the first lens is a convex surface, and the two surfaces of the second lens are concave and convex respectively, the focal length range of the first lens is 1mm~20mm, the focal length range of the second lens is -20mm~-0.5mm, and the non-glued surface of the first lens is an aspherical surface.

[0025] Optionally, the polarization module includes a third lens and a quarter wave plate that are arranged in close contact with each other.

[0026] According to the backlight module and AR device proposed in the embodiments of the present invention, the backlight module applied to the AR device includes a light source and a light guide component for forming an illumination light path, the light source is used to emit a first light beam carrying image information, and the light guide component is used to perform homogenization on the first light beam and also export the first light beam to an imaging component of the AR device; the light guide component includes a light guide block, the light guide block has a first transmission surface and a second reflection surface that are relatively set, and a first reflection surface and a second transmission surface that are relatively set, the first transmission surface is arranged with a plurality of first homogenization structures, the first reflection surface is arranged with a plurality of second homogenization structures, and the second transmission surface is arranged with a brightening module; the first homogenization structure is located outside the light guide block and is arranged adjacent to the light source, and is used to couple the first light beam into the light guide block and homogenize the first light beam; the second homogenization structure is located in the light guide block, and is used to reflect and homogenize the light beam incident on the second homogenization structure; the brightening module is arranged adjacent to the imaging component, and is used to export the light beam received by the second transmission surface to the imaging component. Therefore, by setting up the light guide component, the architecture of the illumination light path of the AR device is changed, the use of collimating mirrors and relay lenses is reduced, the length of the illumination light path is shortened, and the volume of the AR device is reduced.

[0027] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0029] Figure 1 It is a structural schematic diagram of the illumination optical path of an AR device in the related art;

[0030] Figure 2 is a schematic structural diagram of a backlight module proposed in an embodiment of the present invention;

[0031] Figure 3 is a structural schematic diagram of a first light homogenization structure of a backlight module proposed in an embodiment of the present invention;

[0032] Figure 4 is a structural schematic diagram of a second light uniforming structure of a backlight module proposed in an embodiment of the present invention;

[0033] Figure 5 is a structural schematic diagram of a brightness enhancement module of a backlight module proposed in an embodiment of the present invention;

[0034] Figure 6 is a schematic diagram of the structure of an AR device proposed in an embodiment of the present invention;

[0035] Figure 7 is a schematic diagram of the MTF of an AR device provided in an embodiment of the present invention;

[0036] Figure 8 Schematic diagram of the distortion of the AR device proposed in the embodiment of the present invention. DETAILED DESCRIPTION

[0037] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0038] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0039] Figure 1It is a structural schematic diagram of the illumination optical path of an AR device in the related art. Among them, the illumination optical path 1 includes, in the direction of light transmission, LED light source 01, first lens 02, second lens 03, light homogenizer 04 and third lens 05 in sequence. The LED light source 01 emits Lambertian light, which is deflected by the first lens 02, the second lens 03, the light homogenizer 04 (which can be a compound eye light homogenizer) and the third lens 05, and then enters the imaging optical path 2, and the Lambertian light is incident on the optical waveguide of the AR device through the imaging optical path 2 for transmission, so that the corresponding image can be seen at the coupling end of the optical waveguide. Since a spacing is required between each lens and each lens itself has a corresponding thickness, the length of the illumination optical path along the light transmission direction is longer and the overall volume is larger. Exemplarily, when the illumination optical path is matched with a 0.25-inch LCOS chip, the length is at least 8 mm, and with the imaging optical path, the overall volume is 1.1 cc.

[0040] Therefore, based on the above problems, the embodiment of the present invention proposes a backlight module, the overall volume of which can be less than 0.55cc. Figure 1 In the direction of light source transmission, the length of the lighting light path can be shortened by more than 60%.

[0041] Figure 2 is a schematic diagram of the structure of the backlight module proposed in an embodiment of the present invention. The backlight module can be applied to AR devices, such as Figure 2 As shown, the backlight module 100 includes: a light source 101 and a light guide component 102 for forming an illumination light path, the light source 101 is used to emit a first light beam A carrying image information, the light guide component 102 is used to homogenize the first light beam A and also guide the first light beam A to an imaging component 103 of an AR device; the light guide component 102 includes a light guide block 1021, the light guide block 1021 has a first transmission surface 021 and a second reflection surface 022 arranged opposite to each other, and a first reflection surface 023 and a second transmission surface 024 arranged opposite to each other, and the first transmission surface 021 is arranged with a plurality of first homogenization structures 0 25, a plurality of second light homogenizing structures 026 are arranged on the first reflective surface 023, and a brightening module 027 is arranged on the second transmissive surface 024; wherein, the first light homogenizing structure 025 is located outside the light guide block 1021 and is arranged adjacent to the light source 101, and is used to couple the first light beam A into the light guide block 1021, and homogenize the first light beam A; the second light homogenizing structure 026 is located in the light guide block 1021, and is used to reflect and homogenize the light beam incident on the second light homogenizing structure 026; the brightening module 027 is arranged adjacent to the imaging component 103, and is used to export the light beam received by the second transmissive surface 024 to the imaging component 103.

[0042] Among them, the material of the light guide block 1021 can be a molded material, such as plastic PC. The light source 101 can be an LED light source. After the light source 101 emits the first light beam A, it irradiates the first light homogenizing structure 025. After the first light homogenizing structure 025 homogenizes the first light beam A, it is transmitted through the first transmission surface 021 and enters the light guide block 1021. It should be noted here that the incident angle between the first light beam A and the first light homogenizing structure 025 must meet the total reflection angle of the first light homogenizing structure 025, so that the partial light loss of the first light beam A in the first light homogenizing structure 025 is less. In addition, in some embodiments, the first transmission surface 021 can be coated with an anti-reflection film so that the first light beam A can enter the light guide block 1021 more.

[0043] After the first light beam A enters the light guide block 1021, it is reflected inside the light guide block 1021. In order to better homogenize the light, a second homogenizing structure 026 is set on the first reflection surface 023. In order to enable the second homogenizing structure 026 to play a homogenizing role, it is necessary to perform optical path simulation or corresponding calculation in advance so that the first light beam A can be irradiated on the second homogenizing structure 026 after entering the light guide block 1021. In this way, the second homogenizing structure 026 can reflect and homogenize the first light beam A entering the light guide block 1021, and the reflected first light beam A may hit the second reflection surface 022 or the second transmission surface 024. When hitting the second reflection surface 022, the second reflection surface 022 may reflect the first light beam A to the second transmission surface 024, or reflect it to the second homogenizing structure 026. When hitting the second transmission surface 024, it is directly emitted. In this way, the first light beam A is reflected in the light guide block 1021 all the time, and finally emitted to the imaging component 103, and transmitted to the optical waveguide through the imaging component 103.

[0044] It should be noted that the second reflective surface 022 may be coated with an anti-reflection film to prevent the first light beam A from transmitting from the second reflective surface 022. Similarly, the first reflective surface 023 may also be coated with an anti-reflection film to prevent the first light beam A from transmitting from the first reflective surface 023. This reduces the loss of the first light beam A. The second transmission surface 024 may be provided with a brightness enhancement module 027, which can further adjust the light spot shape and light intensity of the first light beam A.

[0045] In one embodiment, the light guide assembly 102 may be disposed in a housing, and a light hole (aperture) may be disposed in the portion of the housing corresponding to the light source 101, and a light hole (aperture) may be disposed in the portion corresponding to the imaging assembly 103. The inner wall of the housing may be coated with a high-reflection film.

[0046] Therefore, by setting the light source 101 and the light guide component 102 to form the backlight module 100, the lighting light path is made compact and modular, the first light beam A can be evenly distributed and the transmission direction can be changed, the use of collimating lenses and relay lenses is reduced, and the size of the AR device is greatly reduced.

[0047] Optionally, continue to refer to Figure 2 The light guide block 1021 is a rectangular parallelepiped. The first light beam A can pass through the first light homogenizing structure 025, the first transmission surface 021, the second light homogenizing structure 026, the second reflection surface 022, the second transmission surface 024 and the brightness enhancement module 027 in sequence, and then be emitted from the light guide component 102. The optical axis of the light beam emitted from the light guide component 102 is perpendicular to the plane where the second transmission surface 024 is located.

[0048] It should be noted that, after passing through the light guide component 102 , the first light beam A can be emitted in a direction perpendicular to the second transmission surface 024 , so as to meet the light incidence requirement of the rear imaging component 103 .

[0049] Optionally, Figure 3 is a schematic structural diagram of a first light homogenization structure of a backlight module proposed in an embodiment of the present invention, such as Figure 2 and Figure 3 As shown, the first light homogenizing structure 025 is a pyramid microstructure. In the direction from the first transmission surface 021 to the second reflection surface 022, the first light homogenizing structure 025 has a first bottom surface 025a and a second bottom surface 025b in sequence. The first bottom surface 025a is far away from the first transmission surface 021, and the second bottom surface 025b is attached to the first transmission surface 021. The area of ​​the first bottom surface 025a is smaller than the area of ​​the second bottom surface 025b; the ratio of the area of ​​the second bottom surface 025b to the area of ​​the first transmission surface 021 is in the range of 1:5~1:15; the bottom angle of the pyramid microstructure is in the range of 45°~90°.

[0050] Optionally, the pyramid microstructure is a quadrangular pyramid microstructure.

[0051] It should be noted that, in one embodiment, the side length of the second bottom surface 025b of the pyramid microstructure and the height of the pyramid microstructure can be 0.2 mm, and the four bottom angles α can be 60°. It can be arranged in the light passing area of ​​the first transmission surface 021. In this way, the first light beam A emitted by the light source 101 can be incident on the pyramid microstructure, and can be incident at the total reflection angle of the pyramid microstructure, so that the first light beam A can be fully coupled into the light guide block 1021, and the first light beam A is homogenized for the first time. In other embodiments, the pyramid microstructure can also be a triangular pyramid microstructure or a multi-sided pyramid microstructure.

[0052] Optionally, Figure 4 2 is a schematic diagram of the structure of the second light homogenization structure of the backlight module proposed in an embodiment of the present invention, such as 2 and Figure 4As shown, the second light homogenizing structure 026 is a spherical microstructure. In the direction in which the first reflective surface 023 points to the second transmissive surface 024, the second light homogenizing structure 026 has a third bottom surface 026a and a spherical surface 026b in sequence. The third bottom surface 026a is in contact with the first reflective surface 023, and the spherical surface 026b is located in the light guide block 1021, away from the first reflective surface 023. The ratio of the area of ​​the third bottom surface 026a to the area of ​​the first reflective surface 023 is in the range of 1:5~1:15, and the ratio of the spherical radius of the spherical microstructure to the vector height is in the range of 1~2.

[0053] It should be noted that, in one embodiment, the radius of the third bottom surface 026a of the spherical microstructure is 0.1 mm, and the arrow height is 0.2 mm. It can be arranged in the light reflection area of ​​the first reflection surface 023. In this way, the first light beam A entering the light guide block 1021 can be reflected when it is irradiated on the second uniform light structure 026. If the first light beam A enters in multiple directions, the second uniform light structure 026 can reflect the first light beam A in multiple directions, so that the first light beam A is more uniform.

[0054] Optionally, the bottom surface of the spherical microstructure is convex along the direction from the first reflective surface 023 to the second transmissive surface 024, or the spherical microstructure is a hollow structure. This arrangement can reduce the weight of the light guide component 102, save materials, and reduce costs.

[0055] Optionally, a reflective layer is further provided on the spherical surface of the spherical microstructure, so as to increase the reflective capability of the spherical microstructure to the first light beam A and reduce the loss of light during the reflection process.

[0056] Optionally, Figure 5 is a schematic structural diagram of a brightness enhancement module of a backlight module according to an embodiment of the present invention. Figure 2 and Figure 5 As shown, the brightness enhancement module 027 has a first brightness enhancement film 271 and a second brightness enhancement film 272 arranged in a direction from the first reflective surface 023 to the second transmissive surface 024; wherein the first brightness enhancement film 271 is attached to the second transmissive surface 024, and there is a gap between the first brightness enhancement film 271 and the second brightness enhancement film 272; the extension direction of the third microstructure 071 on the first brightness enhancement film 271 and the extension direction of the fourth microstructure 072 on the second brightness enhancement film 272 are perpendicular to each other.

[0057] Among them, by setting the first brightness enhancement film 271 and the second brightness enhancement film 272, the spot shape of the light beam emitted from the self-light guiding component 102 can be constrained along the horizontal axis and the vertical axis at the same time, so as to focus and converge, ensure the aperture angle of the emitted light in two vertical directions, and improve the brightness of the spot. Figure 5 The brightness enhancement module 027 shown is an example. In other examples, the position of the first brightness enhancement film 271 and the position of the second brightness enhancement film 272 can be interchanged.

[0058] Optionally, the third microstructure 071 and the fourth microstructure 072 are triangular prism structures, the cross-sectional triangular base angle of the triangular prism structure ranges from 40° to 50°, and the ratio of the side length of the bottom side of the triangular prism structure to the side length of the light guide block 1021 parallel to the bottom side of the triangular prism structure ranges from 1:100 to 1:300.

[0059] Among them, Figure 5 In the figure shown, the ratio of the side length of the third microstructure 071 to the attached first brightness enhancement film 271 can be 1:100-1:300, that is, 100-300 prism structures can be attached to the brightness enhancement film. In this way, when light enters the prism structure, the light can be deflected by the two sides of the prism structure, and the light beam can be shrunk.

[0060] In one embodiment, the base angle of the prism structure may be 45°, and the length of the side of the triangle may be 0.024 mm.

[0061] Figure 6 Schematic diagram of the structure of the AR device proposed in the embodiment of the present invention. Figure 5 As shown, the AR device includes the backlight module 100 of any embodiment of the present invention, and further includes: an imaging component 103 for forming an imaging light path;

[0062] The imaging component 103 includes: a polarization beam splitting prism 1031, a polarizing element 1032 and an imaging lens 1033 respectively disposed on two opposite sides of the polarization beam splitting prism 1031, and a polarization module 1034 and an LCOS module 1035 respectively disposed on the other two opposite sides of the polarization beam splitting prism;

[0063] Among them, the polarizing element 1032 is used to polarize the first light beam A emitted by the backlight module 100 to form a polarized light beam, the polarization beam splitting prism 1031 is used to reflect the polarized light beam to form a second light beam, and transmit it to the LCOS module 1035; the LCOS module 1035 reflects the second light beam to form a third light beam, and transmits it to the polarization beam splitting prism 1031; the polarization beam splitting prism 1031 is used to transmit the third light beam and transmit it to the polarization module 1034; the polarization module 1034 is used to reflect the third light beam to form a fourth light beam and transmit it to the polarization beam splitting prism 1031, the polarization beam splitting prism 1031 is used to reflect the fourth light beam to form a fifth light beam and transmit it to the imaging lens 1033, and the imaging lens 1033 outputs it to the waveguide of the AR device.

[0064] It should be noted that the present embodiment adopts the LCOS (Liquid Crystal on Silicon) module. Compared with DMD, the LCOS module has the advantages of smaller size, more mature technology and lower cost. Although it is not as good as the self-luminous microLED optical machine solution in terms of size, the resolution of microLED is relatively low at present and it is not yet possible to achieve mature, stable and low-cost mass production; therefore, the LCOS optical machine solution is the best choice for AR optical machines at present.

[0065] Specifically, the first light beam A emitted by the light source 101 is homogenized by the backlight module 100 and then converted into S polarized light by the polarizer 1032 (POL). The S polarized light enters the polarization beam splitter prism 1031 (PBS) and is reflected and transmitted downward to reach the LCOS module 1035. After being reflected by the LCOS module 1035, the S polarized light is converted into P polarized light and re-enters the polarization beam splitter prism 1031 (PBS). At this time, the polarization beam splitter prism 1031 (PBS) is in a transmission mode for the P polarized light and is transmitted upward to the polarization module 1034. After being reflected by the polarization module 1034 (with a QWP film (1 / 4 wave plate) in the meantime), the P polarized light is converted into S polarized light again and is transmitted downward again and is reflected by the polarization beam splitter prism 1031 (PBS) to enter the imaging lens 1033. At this point, the light transmission is completed and is ready to enter the waveguide. The backlight illumination scheme in this embodiment replaces the traditional illumination optical path architecture and adjusts some lenses of the imaging optical path, and combines the polarization multiplexing optical path to achieve the miniaturization of the optical machine of the LCOS solution.

[0066] Optionally, continue to refer to Figure 6 , the LCOS module 1035 includes a first lens G1, a second lens G2 and an LCOS chip 351, and the first lens G1 and the second lens G2 are glued together;

[0067] The optical focal length of the first lens G1 is positive, the optical focal length of the second lens G2 is negative, and the second lens G2 is arranged adjacent to the LCOS chip 351; at least one surface of the first lens G1 is a convex surface, and the two surfaces of the second lens G2 are concave and convex respectively. The focal length range of the first lens G1 is 1mm~20mm, the focal length range of the second lens G2 is -20mm~-0.5mm, and the non-cemented surface of the first lens G1 is an aspherical surface.

[0068] It should be noted that, in order to ensure small volume and imaging quality, the first lens G1 and the second lens G2 are glued together, wherein the first lens G1 is a positive lens, the second lens G2 is a negative lens, and the side of the first lens G1 away from the LCOS chip 351 is an aspheric surface, and the aspheric coefficient is -100~+100. In this way, the system distortion can be greatly reduced and the vertical size can be miniaturized.

[0069] In one embodiment, the focal length of the first lens G1 may be 6 mm, the focal length of the second lens G2 may be -12 mm, and the aspheric coefficient may be -1.2.

[0070] Alternatively, if Figure 6 As shown, the polarization module 1034 includes a third lens G3 and a quarter wave plate 341 which are arranged in close contact.

[0071] The third lens G3 may be a positive lens with a focal length of 72 mm. The quarter wave plate 341 is used to change the phase of the light beam irradiated thereto so as to change the polarization direction of the light beam.

[0072] Therefore, in a specific embodiment, based on the LCOS chip design with a light-emitting surface size of 0.25 inches (aspect ratio of 16:10), FOV 54°, the illumination LED is selected as Osram KRTTB CRLM1.33 model, and the optical machine exit pupil is 4mm, the design results are as follows:

[0073] The imaging lens 1033 is a positive lens with a focal length of 72 mm; the third lens G3 is a positive lens with a focal length of 72 mm; the first lens G1 is a positive lens with a focal length of 6 mm and an aspheric coefficient of -1.2; the second lens G2 is a negative lens with a focal length of -12 mm; the side angle of the first homogenizing structure 025 is 60 degrees and the side length is 0.2 mm;

[0074] The radius of the second light homogenizing structure 026 is 0.1 mm, and the sagittal height is 0.2 mm; the side angle of the microstructure on the brightness enhancement film is 45 degrees, and the side length is 0.024 mm.

[0075] Through the above design, the total length of the lighting is 3mm; the lighting efficiency is 15%, the uniformity is greater than 80%, and the volume is less than 0.55cc; compared with the traditional structure length (8mm), it is reduced by 60% and the optical efficiency is attenuated by 25%.

[0076] Figure 7 : is a schematic diagram of the MTF of the AR device proposed in the embodiment of the present invention. Figure 7 As shown, the imaging quality MTF>0.4@1161p / mm. Among them, Figure 7 The solid line indicates the meridian, the dashed line indicates the sagittal, and the black line indicates the diffraction limit.

[0077] Figure 8 is a schematic diagram of the distortion of the AR device proposed in an embodiment of the present invention, such as Figure 8As shown, by adjusting the cemented aspheric properties in the architecture of the imaging component 103, the system distortion also performs well under a large field of view, with TV distortion within 3%, which is 40% lower than the distortion of the traditional architecture. Among them, the SMIA-TV distortion (H / V) is: 1.0694% / 2.9768%; the Delta absolute distortion (right / left / bottom / top) is: 44.75mm / 44.75mm / 75.758mm / 76.9966mm. The RIAA-TV distortion (right / left / bottom / top) is: 0.5349% / 0.5349% / 1.4763% / 1.5005%. The projection ratio is 1.1954.

[0078] Therefore, this embodiment is based on an optical architecture solution with variable LCOS size, and achieves miniaturization through compact illumination optical path size and folded imaging optical path size.

[0079] In summary, according to the backlight module and AR device proposed in the embodiments of the present invention, the backlight module applied to the AR device includes a light source and a light guide component for forming an illumination light path, the light source is used to emit a first light beam carrying image information, and the light guide component is used to homogenize the first light beam and also export the first light beam to the imaging component of the AR device; the light guide component includes a light guide block, the light guide block has a first transmission surface and a second reflection surface that are relatively set, and a first reflection surface and a second transmission surface that are relatively set, the first transmission surface is arranged with a plurality of first homogenizing structures, the first reflection surface is arranged with a plurality of second homogenizing structures, and the second transmission surface is arranged with a brightening module; the first homogenizing structure is located outside the light guide block and is arranged adjacent to the light source, and is used to couple the first light beam into the light guide block and homogenize the first light beam; the second homogenizing structure is located in the light guide block, and is used to reflect and homogenize the light beam incident on the second homogenizing structure; the brightening module is arranged adjacent to the imaging component, and is used to export the light beam received by the second transmission surface to the imaging component. Therefore, by setting up the light guide component, the architecture of the illumination light path of the AR device is changed, the use of collimating mirrors and relay lenses is reduced, the length of the illumination light path is shortened, and the volume of the AR device is reduced.

[0080] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A backlight module, characterized in that: Applied to AR devices, the backlight module includes: a light source and a light guide component for forming an illumination light path, the light source is used to emit a first light beam carrying image information, and the light guide component is used to homogenize the first light beam and guide the first light beam to an imaging component of the AR device; The light guide assembly includes a light guide block, the light guide block has a first transmission surface and a second reflection surface that are oppositely arranged, and a first reflection surface and a second transmission surface that are oppositely arranged, the first transmission surface is arranged with a plurality of first light homogenizing structures, the first reflection surface is arranged with a plurality of second light homogenizing structures, and the second transmission surface is arranged with a brightness enhancement module; Wherein, the first light homogenizing structure is located outside the light guide block and is arranged adjacent to the light source, and is used to couple the first light beam into the light guide block and homogenize the first light beam; the second light homogenizing structure is located in the light guide block, and is used to reflect and homogenize the light beam incident on the second light homogenizing structure; the brightening module is arranged adjacent to the imaging component, and is used to export the light beam received by the second transmission surface to the imaging component; the first light homogenizing structure is a pyramid microstructure, and the second light homogenizing structure is a spherical microstructure. After entering the light guide block, the first light beam can be irradiated onto the second light homogenizing structure, and the second light homogenizing structure can reflect and homogenize the first light beam entering the light guide block, and the reflected first light beam hits the second reflection surface or the second transmission surface; when hitting the second reflection surface, the second reflection surface reflects the first light beam to the second transmission surface, or reflects it to the second light homogenizing structure; when hitting the second transmission surface, it is directly emitted; The incident angle between the first light beam and the first light homogenizing structure satisfies the total reflection angle of the first light homogenizing structure.

2. The backlight module according to claim 1, characterized in that: The light guide block is a rectangular parallelepiped, and the first light beam can pass through the first light uniforming structure, the first transmission surface, the second light uniforming structure, the second reflection surface, the second transmission surface and the brightness enhancement module in sequence, and then be emitted from the light guide component, and the optical axis of the light beam emitted from the light guide component is perpendicular to the plane where the second transmission surface is located.

3. The backlight module according to claim 1 or 2, characterized in that: The first light homogenizing structure is a pyramid microstructure, and in the direction from the first transmission surface to the second reflection surface, the first light homogenizing structure has a first bottom surface and a second bottom surface in sequence, the first bottom surface is away from the first transmission surface, the second bottom surface is in contact with the first transmission surface, and the area of ​​the first bottom surface is smaller than the area of ​​the second bottom surface; The ratio of the area of ​​the second bottom surface to the area of ​​the first transmission surface is in the range of 1:5 to 1:15; and the bottom angle of the pyramid microstructure is in the range of 45° to 90°.

4. The backlight module according to claim 3, characterized in that: The pyramid microstructure is a quadrangular pyramid microstructure.

5. The backlight module according to claim 1 or 2, characterized in that: The second light homogenizing structure is a spherical microstructure. In the direction in which the first reflective surface points to the second transmissive surface, the second light homogenizing structure sequentially comprises a third bottom surface and a spherical surface, the third bottom surface is in contact with the first reflective surface, and the spherical surface is located in the light guide block and is arranged away from the first reflective surface; The ratio of the area of ​​the third bottom surface to the area of ​​the first reflecting surface is in the range of 1:5 to 1:15, and the ratio of the spherical radius to the vector height of the spherical microstructure is in the range of 1 to 2.

6. The backlight module according to claim 5, characterized in that: The bottom surface of the spherical microstructure is convex along the direction from the first reflective surface to the second transmissive surface, or the spherical microstructure is a hollow structure.

7. The backlight module according to claim 5, characterized in that: A reflective layer is also arranged on the spherical surface of the spherical microstructure.

8. The backlight module according to claim 1 or 2, characterized in that: The brightness enhancement module comprises a first brightness enhancement film and a second brightness enhancement film arranged in a direction from the first reflective surface to the second transmissive surface; The first brightness enhancement film is attached to the second transmission surface, and there is a gap between the first brightness enhancement film and the second brightness enhancement film; the extension direction of the third microstructure on the first brightness enhancement film is perpendicular to the extension direction of the fourth microstructure on the second brightness enhancement film.

9. The backlight module according to claim 8, characterized in that: The third microstructure and the fourth microstructure are triangular prism structures, the cross-sectional triangular base angle of the triangular prism structure ranges from 40° to 50°, and the ratio of the side length of the bottom side of the triangular prism structure to the side length of the light guide block parallel to the bottom side of the triangular prism structure ranges from 1:100 to 1:

300.

10. An AR device, characterized in that: The backlight module comprises the backlight module as claimed in any one of claims 1 to 9, further comprising: an imaging component for forming an imaging light path; The imaging assembly comprises: a polarization beam splitter prism, a polarizing element and an imaging lens respectively arranged on two opposite sides of the polarization beam splitter prism, and a polarization module and an LCOS module respectively arranged on the other two opposite sides of the polarization beam splitter prism; Among them, the polarizing element is used to polarize the first light beam emitted by the backlight module to form a polarized light beam, the polarization beam splitting prism is used to reflect the polarized light beam to form a second light beam, and transmit it to the LCOS module; the LCOS module reflects the second light beam to form a third light beam, and transmits it to the polarization beam splitting prism; the polarization beam splitting prism is used to transmit the third light beam and transmit it to the polarization module; the polarization module is used to reflect the third light beam to form a fourth light beam and transmit it to the polarization beam splitting prism, the polarization beam splitting prism is used to reflect the fourth light beam to form a fifth light beam and transmit it to the imaging lens, and the imaging lens outputs it to the waveguide of the AR device.

11. The AR device according to claim 10, characterized in that: The LCOS module comprises a first lens, a second lens and an LCOS chip, wherein the first lens and the second lens are glued together; The optical focal power of the first lens is positive, the optical focal power of the second lens is negative, and the second lens is arranged adjacent to the LCOS chip; at least one surface of the first lens is a convex surface, and the two surfaces of the second lens are concave and convex respectively, the focal length range of the first lens is 1mm~20mm, the focal length range of the second lens is -20mm~-0.5mm, and the non-glued surface of the first lens is an aspherical surface.

12. The AR device according to claim 10, characterized in that: The polarization module comprises a third lens and a quarter wave plate which are arranged in close contact.

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