Miniature projection module and head-mounted display device

Abstract

A miniature projection module comprises: an illumination assembly (10) configured to provide a polarized illumination light; a display chip (30) configured to modulate the polarized illumination light into a polarized image light; the relay assembly (20) is configured to transmit the polarized illumination light to the display chip (30) and transmit the polarized image light to the projection assembly (40), and the relay assembly (20) comprises a polarized light splitting assembly (22); and the projection assembly (40) is configured to project and image the polarized image light, the projection assembly (40) comprises a first projection sub-lens (411) and a second projection sub-lens (412), the first projection sub-lens (411) is arranged in a light path between the polarized light splitting assembly (22) and the display chip (30), and the second projection sub-lens (412) is arranged in a light path between the polarized light splitting assembly (22) and the display chip (30). The second projection sub-lens (412) and the first projection sub-lens (411) are arranged on two opposite sides of the polarization beam splitting assembly (22), and the optical axis of the second projection sub-lens (412) and the optical axis of the first projection sub-lens (411) are located on the same straight line.

Description

Micro projection module and head-mounted display device Technical Field

[0001] The present invention relates to the field of optical imaging technology, and in particular to a micro projection module and a head-mounted display device including the micro projection module. Background Art

[0002] Augmented Reality (AR) technology seamlessly integrates real-world information with virtual worlds. It uses computers and other scientific technologies to simulate and overlay physical information that is difficult to experience within a certain time and space in the real world, thereby providing people with a sensory experience beyond reality. Because AR technology overlays virtual objects or images on real environments, it has enormous application potential in many fields.

[0003] The projection module, also known as the optical engine, is a key component in augmented reality technology. Its imaging quality and size directly determine the quality of the user experience. How to strike a balance between good imaging quality and compact size has always been one of the focuses of major manufacturers.

[0004] With the recent advancement of microdisplay chip technology, the mainstream micro-projection display chips now include TFT-LCD, LCoS, DMD, and MicroLED. Monochrome MicroLED light engines have become popular in the market due to their lightweight design. However, monochrome AR products have significant application limitations and fail to meet the expectations of consumers accustomed to vibrant visuals. Full-color AR products remain the industry trend. MicroLED chips are limited by bottlenecks in material technology and quantum dot conversion technology, and the luminous efficiency of red chips cannot be resolved in the short term. This has hindered the commercialization of full-color AR light engines based on MicroLED chips, and RGB full-color MicroLED chips are also unlikely to be launched in the near future. TFT-LCD chips, on the other hand, have disadvantages such as low contrast, low light efficiency, low brightness, and low resolution. Currently, the optimal technical solutions for full-color AR products are LCoS or DLP solutions based on DMD chips. In terms of resolution, brightness, contrast, and light efficiency, the two are comparable, with DMD chips slightly superior to LCoS chips. However, due to the global exclusive supply of DMD chips, LCoS chips have a wider selection of mass-produced suppliers, giving LCoS light engines a significant cost advantage.

[0005] Existing LCoS optical machines usually set the lighting system and projection system on both sides of the PBS prism. Due to the limitation of optical focal length, the lighting, relay and projection systems have a maximum length. The overall optical machine has a linear structure and is difficult to reduce in size. It cannot meet the trend of increasing miniaturization and lightweight of near-eye display devices. Therefore, a small-sized and lightweight micro-projection module and a head-mounted display device compatible with the micro-projection module are needed to meet market demand.

[0006] Summary of the Invention

[0007] The object of the present invention is to provide a micro projection module and a head-mounted display device that can meet the market trend of miniaturization and lightweighting.

[0008] In order to achieve the above-mentioned object of the invention, according to a first aspect of the present application, a micro projection module is provided, characterized in that it includes:

[0009] an illumination assembly configured to provide polarized illumination light; and

[0010] A display chip configured to modulate the polarized illumination light into polarized image light; and

[0011] a relay component configured to transmit the polarized illumination light to the display chip and transmit the polarized image light to the projection component, the relay component comprising a polarization beam splitter component; and

[0012] A projection assembly is configured to project the polarized image light into an image, the projection assembly comprising a first projection sub-lens and a second projection sub-lens, wherein the first projection sub-lens is disposed in the optical path between the polarization beam splitting assembly and the display chip, and is configured to provide a transmission path for the polarized illumination light and the polarized image light and perform optical path correction, and the second projection sub-lens and the first projection sub-lens are disposed on opposite sides of the polarization beam splitting assembly, and the optical axes of the second projection sub-lens and the first projection sub-lens are co-linear.

[0013] According to an embodiment of the first aspect of the present application, the number of lenses of the first projection sub-lens is twice or more the number of lenses of the second projection sub-lens.

[0014] According to an embodiment of the first aspect of the present application, the lighting assembly includes: an illumination light source, the illumination light source being configured to emit multiple monochromatic illumination lights; a collimating device; a color combining device; a light homogenizing device; and a polarizing device, wherein the collimating device and the color combining device are arranged in an optical path between the illumination light source and the polarizing device, and are configured to collimate the multiple monochromatic illumination lights into one combined-color illumination light, the optical path of the combined-color illumination light being perpendicular to the optical axis of the first projection sub-lens, and the polarizing device being configured to polarize the combined-color illumination light into the polarized illumination light.

[0015] According to an embodiment of the first aspect of the present application, the polarizing device is a first polarizer, which is configured to pass polarized light with a first polarization state and block polarized light with a second polarization state, and the polarization splitting component is configured to reflect polarized light with the first polarization state and transmit polarized light with the second polarization state, wherein the polarization directions of the first polarization state and the second polarization state are perpendicular to each other.

[0016] According to an embodiment of the first aspect of the present application, the first projection sub-lens and the second projection sub-lens jointly meet the projection requirements of the optical system.

[0017] According to an embodiment of the first aspect of the present application, the display chip is an LCoS chip.

[0018] According to a second aspect of the present application, a head-mounted display device is provided, characterized in that it includes:

[0019] At least one of the micro-projection modules; and

[0020] At least one lens unit, a frame, two temples, and a computing unit; the micro-projection module is disposed in an area of ​​the temples close to the frame. According to an embodiment of the second aspect of the present application, the optical axis of the first projection sub-lens is aligned with the extension direction of the temples.

[0021] According to an embodiment of the second aspect of the present application, the at least one lens unit is an optical waveguide including an incoupling region and an outcoupling region.

[0022] According to an embodiment of the second aspect of the present application, the optical axis of the second projection sub-lens is aligned with the center of the coupling-in region.

[0023] In the following description, some additional embodiments and features are set forth, and those skilled in the art will understand after reviewing the specification or learn these embodiments and features through practice of the disclosed subject matter. A further understanding of the features and advantages of the present disclosure may be achieved by reference to the remainder of the specification and drawings, which constitute a part of this application. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. In the accompanying drawings, unless otherwise specified, the same reference numerals are used to represent the same components.

[0025] FIG1 is a schematic diagram of a three-dimensional structure of an optical system of a micro-projection module according to some embodiments of the present invention;

[0026] FIG2A is a plan view of a micro-projection module optical system according to some embodiments of the present invention;

[0027] FIG2B is a left plan view of the portion within the dotted line frame in FIG2A ;

[0028] FIG3A is a schematic diagram of the three-dimensional structure of AR glasses according to some embodiments of the present invention;

[0029] FIG3B is a plan view of AR glasses according to some embodiments of the present invention;

[0030] 3C is a right plan view of AR glasses according to some embodiments of the present invention. DETAILED DESCRIPTION

[0031] The concept of the present invention is further described in detail below with reference to specific embodiments. It should be noted that the embodiments listed here are only used to clearly illustrate the inventive concept of the present invention and should not be understood as limiting the present invention. The technical features of the micro-projection module and head-mounted display device involved herein, as long as they do not violate the laws of nature or technical specifications, and under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0032] In the description of this application, it should be noted that for directional words, such as the terms "center", "horizontal", "longitudinal", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and so on, the directions and positional relationships indicated are based on the directions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and cannot be understood as limiting the specific scope of protection of this application.

[0033] It should be noted that the terms "first", "second", etc. in the description and claims of this application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0034] The terms "comprises" and "having" and any variations thereof in the specification and claims of this application are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus that includes a series of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, product or apparatus.

[0035] It should be noted that, as used in this application, the terms "substantially," "approximately," and similar terms are used as terms of approximation, not as terms of degree, and are intended to account for inherent deviations in measurements or calculations that would be recognized by a person of ordinary skill in the art.

[0036] It should also be noted that, in the description of this application, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections, contact connections, or indirect connections through an intermediate medium; and they can refer to internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0037] Various units, circuits, or other components may be described or stated as being "configured to" perform one or more tasks. In such contexts, "configured to" is used to imply a structure (e.g., a circuit) that performs the one or more tasks during operation by indicating that the unit / circuit / component includes that structure. Additionally, "configured to" may include general structures (e.g., general circuits) manipulated by software and / or firmware to operate in a manner capable of performing the one or more tasks to be addressed. "Configured to" may also include adjusting a manufacturing process (e.g., a semiconductor fabrication facility) to manufacture a device (e.g., an integrated circuit) suitable for implementing or performing the one or more tasks.

[0038] The terms used in this description are only for the purpose of describing specific embodiments and are not intended to be limiting. As used in the specification and the appended claims, the singular forms "a", "an" and "the" are intended to also encompass the plural form, unless the context clearly indicates otherwise. It will also be understood that the terms "and / or" used herein refer to and encompass any and all possible combinations of one or more items in the items listed in association. It will also be understood that the terms "comprises" and / or "comprising" when used in this specification specify the presence of stated features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or their groupings.

[0039] As used herein, the term "if" may be interpreted to mean "when" or "upon" or "in response to determining" or "in response to detecting," depending on the context. Similarly, the phrase "if it is determined that" or "if [stated condition or event] is detected" may be interpreted to mean "upon determining that" or "in response to determining that" or "upon detecting [stated condition or event]" or "in response to detecting [stated condition or event]," depending on the context.

[0040] It should be pointed out that the embodiments shown in the drawings are only used as examples to specifically and vividly explain and illustrate the concept of the present invention. Their size and structure are not necessarily drawn to scale, nor do they constitute a limitation to the concept of the present invention.

[0041] FIG1 is a schematic diagram of the three-dimensional structure of an optical system of a micro-projection module according to an embodiment of the present invention. The micro-projection module includes an illumination component 10, a relay component 20, a display chip 30, and a projection component 40. The illumination component 10 is used to provide polarized illumination light having the same polarization state. The relay component 20 is used to transmit at least a portion of the polarized illumination light from the illumination component 10 to the display chip 30. The display chip 30 is used to modulate the polarized illumination light into polarized image light with image information, and transmit the polarized image light to the projection component 40 again through the relay component 20. The projection component 40 is used to project the modulated polarized image light into an image to other optical components of the head-mounted display device, such as an optical waveguide.

[0042] As shown in Figure 1, R represents red light, G represents green light, B represents blue light, and W represents white light. To distinguish polarized illumination light from polarized image light, polarized illumination light in this application is represented by S-polarized light / P-polarized light, and polarized image light is represented by S'-polarized light / P'-polarized light. The solid line in the figure represents the illumination light path, and the dashed line represents the projection light path. Accordingly, the illumination light path and the optical elements it passes through constitute the illumination system, and the projection light path and the optical elements it passes through constitute the projection system. These details are not further explained below.

[0043] Specifically, as shown in Figures 2A-2B, Figure 2A is a plan view of the optical system of the micro-projection module, and Figure 2B is a plan view of the portion within the dashed box in Figure 2A from the left. The illumination assembly 10 includes an illumination light source 11, a collimator 12, a color combiner 13, a light homogenizer 14, and a polarizer 15. The illumination assembly 10 is configured to provide polarized illumination light having a uniform polarization state.

[0044] The illumination light source 11 may further include a first light source 111, a second light source 112, and a third light source 113. Optionally, the first light source 111 is a red light source, the second light source 112 is a green light source, and the third light source 113 is a blue light source. The light-emitting surfaces of the first light source 111 and the third light source 113 may be arranged on the same plane and adjacent to each other. It is understood that the colors, types, quantities, and combinations of the illumination light sources may also vary and are not limited in the present invention.

[0045] The collimating device 12 includes a first collimating lens group 121 and a second collimating lens group 122. The first collimating lens group 121 and the second collimating lens group 122 each include at least one optical lens, which can be an optical lens group consisting of a spherical lens and a cylindrical lens, or an optical lens group consisting of two lenses of the same type among spherical lenses, cylindrical lenses, and aspherical lenses, or any combination of two types of lenses. In other words, the surface shape of the optical lenses that make up the collimating lens group is not limited in this application.

[0046] The color combining device 13 includes a first selective reflection film 131, a second selective reflection film 132, and a wedge-shaped prism 133. The wedge-shaped prism 133 has two opposing surfaces with a non-zero angle therebetween. The first selective reflection film 131 and the second selective reflection film 132 are disposed on opposing surfaces of the wedge-shaped prism 133, respectively. The first collimating lens group 121 is configured to converge, collimate, and transmit light emitted by the second light source 112 to the first selective reflection film 131. The second collimating lens group 122 is configured to converge, collimate, and transmit light emitted by the first light source 111 and the third light source 113 to the second selective reflection film 132.

[0047] In this alternative embodiment, the first selective reflection film 131 is configured to reflect blue light and transmit green light, while the second selective reflection film 132 is configured to reflect red light and transmit green and blue light. The first selective reflection film 131 is disposed on the lower surface of the wedge-shaped prism 133, opposite the second light source 112. The second selective reflection film 132 is disposed on the upper surface of the wedge-shaped prism 133, opposite the first light source 111 and the third light source 113. The green light emitted by the second light source 112 is collimated by the first collimating lens group 121 and then passes through the first selective reflective film 131, the wedge-shaped prism 133, and the second selective reflective film 132 in sequence. The red light emitted by the first light source 111 is collimated by the second collimating lens group 122 and then reflected by the second selective reflective film 132. The blue light emitted by the third light source 113 is collimated by the second collimating lens group 122 and then passes through the second selective reflective film 132 and the wedge-shaped prism 133 in sequence, reflected by the first selective reflective film 131, and then passes through the wedge-shaped prism 133 and the second selective reflective film 132 again. It is then combined with the aforementioned red and green light to form a beam of white light, which is then passed through the light homogenizer 14 to form a uniform illumination light. The material and properties such as the transmission and reflection ratio of the aforementioned selective reflective films are selected based on the specific color and type of the illumination light source and are not limited to the selective transmission and reflection properties described above. The light homogenizer 14 can be a fly-eye lens or other commonly used light homogenizer to achieve a uniform illumination distribution.

[0048] The uniform illumination light obtained after passing through the light homogenizing device 14 passes through the polarizing device 15 and becomes polarized illumination light with a first polarization state. The polarizing device 15 can be a first polarizer, which is configured to pass only polarized light with a first polarization state and block polarized light with a second polarization state. The polarizing device 15 can also be a first polarization multiplexing element, which is used to pass only polarized light with a first polarization state and convert polarized light with a second polarization state into polarized light with a first polarization state. The polarization directions of the polarized light with the first polarization state and the polarized light with the second polarization state are perpendicular to each other. For example, the polarized light with the first polarization state can be S light in linear polarized light, and the polarized light with the second polarization state can be P light in linear polarized light.

[0049] The relay assembly 20 includes a relay lens 21 and a polarization beam splitter 22 . The relay assembly 20 is configured to transmit the polarized illumination light from the illumination assembly 10 to the display chip 30 .

[0050] Optionally, the relay lens 21 is disposed between the light homogenizer 14 and the polarizer 15 . The uniform illumination light from the light homogenizer 14 is transmitted through the relay lens 21 and then converted into polarized illumination light through the polarizer 15 and enters the polarization splitter assembly 22 .

[0051] The polarization beam splitter assembly 22 further includes a first right-angle prism 221, a second right-angle prism 222, and a polarization beam splitter element 223. Both the first right-angle prism 221 and the second right-angle prism 222 are isosceles right-angle prisms. The first right-angle prism 221 includes a first inclined surface 2211, a first side surface 2212, and a first bottom surface 2213. The second right-angle prism 222 includes a second inclined surface 2221, a second side surface 2222, and a second bottom surface 2223. The first inclined surface 2211 and the second inclined surface 2221 are disposed opposite each other, and the polarization beam splitter element 223 is disposed between the first inclined surface 2211 and the second inclined surface 2221. The polarization beam splitter element 223 can be a polarization beam splitting film, in which case the polarization beam splitter assembly 22 is a PBS prism. For example, during the assembly process, a polarizing beam splitter film can be applied to the first inclined surface 2211 before gluing the first right-angle prism 221 to the second inclined surface 2221 of the second right-angle prism 222. Alternatively, a polarizing beam splitter film can be applied to the second inclined surface 2221 before gluing the second right-angle prism 222 to the first inclined surface 2211 of the first right-angle prism 221. The second bottom surface 2223 can provide a mounting base for the polarizer 15. The polarizer 15 can be attached to the second bottom surface 2223. The polarizer 15 then provides a mounting base for the relay lens 21. The relay lens 21 can be attached to the surface of the polarizer 15.

[0052] It is understood that the polarization beam splitting component 22 includes a first side surface 2212, a first bottom surface 2213, a second side surface 2222, and a second bottom surface 2223. The first side surface 2212 and the second side surface 2222 are arranged opposite and parallel to each other, and the first bottom surface 2213 and the second bottom surface 2223 are arranged opposite and parallel to each other. The first side surface 2212 connects the first bottom surface 2213 and the second bottom surface 2223 and is perpendicular to both. The second bottom surface 2223 is used to receive polarized illumination light from the illumination component 10. After being reflected by the polarization beam splitting element 223, the polarized illumination light turns 90 degrees and passes through the second side surface 2222 to reach the display chip 30. After being modulated by the display chip 30 and having its polarization direction changed, the polarized image light again passes back through the second side surface 2222, transmits through the polarization beam splitting element 223, and then exits through the first side surface 2212.

[0053] The polarization beam splitter 223 is configured to reflect polarized light having a first polarization state and transmit polarized light having a second polarization state, wherein the polarization directions of the first polarization state and the second polarization state are perpendicular to each other.

[0054] The display chip 30 is configured to modulate the polarized illumination light into polarized image light carrying image information and change its polarization state. Exemplarily, polarized light having a first polarization state is converted into polarized light having a second polarization state, where the polarization directions of the first polarization state and the second polarization state are perpendicular to each other. The display chip 30 is preferably an LCoS chip. Due to the characteristics of the LCoS chip, S-polarized light incident on the chip surface is modulated into P'-polarized light carrying image information. It is understandable that since the LCoS chip itself is a polarization light modulator, there is no need to add an additional polarization light modulator. If other types of display chips are used, for display chips without polarization light modulation capabilities, an additional polarization light modulator must be provided on the surface of the display chip to modulate the polarization state of the polarized image light.

[0055] The projection assembly 40 includes a projection lens 41. The projection lens 41 further includes a first projection sub-lens 411 and a second projection sub-lens 412. The projection assembly 40 is configured to project the modulated polarized image light onto other optical components of the head-mounted display device, such as an optical waveguide.

[0056] In an optional embodiment, the polarization beam splitter 223 reflects S-polarized light while transmitting P-polarized light. The polarizer 15 is an S-polarizer. The uniform illumination light passing through the light homogenizer 14 becomes S-polarized light after passing through the polarizer 15, is incident perpendicularly to the second bottom surface 2223, enters the second right-angle prism 222, enters the polarization beam splitter component 22, and is reflected at the polarization beam splitter element 223. The S-polarized light after turning 90° is emitted perpendicularly to the second side surface 2222 of the second right-angle prism 222, is transmitted to the surface of the display chip 30 through the first projection sub-lens 411, is modulated into P'-polarized light by the display chip 30, passes through the first projection sub-lens 411 in the opposite direction again, enters the polarization beam splitter component 22, is transmitted at the polarization beam splitter element 223, and is emitted from the first side surface 2212 of the polarization beam splitter component 22. Finally, the P'-polarized light is modulated by the second projection sub-lens 412 and emitted to form an image.

[0057] The first projection sub-lens 411 is an optical path correction device, that is, a transmissive element with an optical path correction function. The optical path correction function in the lighting system refers to the shaping function of the light source, such as focusing, and in the projection system refers to the balancing function of the object-image relationship and aberration. Preferably, the first projection sub-lens 411 is a lens group composed of at least two optical lenses. The first projection sub-lens 411 is arranged in the optical path between the polarization beam splitting component 22 and the display chip 30. The first projection sub-lens 411 is arranged outside the second side surface 2222, and the optical axis is perpendicular to the second side surface 2222. In an optional embodiment, the first projection sub-lens 411 is used to converge the S-polarized light emitted from the polarization beam splitting component 22 and maintain it within a specific range, and transmit it to the display chip 30. That is, the light passing through the first projection sub-lens 411 is part of the illumination optical path.

[0058] After being modulated by the display chip 30, the polarized image light carrying image information, or P'-polarized light in an optional embodiment, passes through the first projection sub-lens 411 again, entering perpendicularly from the second side surface 2222 of the second right-angle prism 222, entering the second right-angle prism 222, then transmitting through the polarization beam splitter 223, entering the first right-angle prism 221, and then exiting perpendicularly from the first side surface 2212 of the first right-angle prism 221. It can be understood that the light passing through the first projection sub-lens 411 at this time constitutes part of the projection optical path. That is, for the entire optical system, the first projection sub-lens 411 simultaneously performs a correction function for both the illumination optical path and the projection optical path. Part of the optical path in the relay system is reused by both the illumination system and the projection system, making the micro-projection module more miniaturized.

[0059] The second projection sub-lens 412 is disposed outside the first side surface 2212, with its optical axis perpendicular to the first side surface 2212. Specifically, the second projection sub-lens 412 and the first projection sub-lens 411 are disposed on opposite sides of the polarization beam splitting assembly 22, with their optical axes aligned. It is understood that the second projection sub-lens 412 also functions as an optical path correction device. The second projection sub-lens 412 includes at least one optical lens. Neither the first projection sub-lens 411 nor the second projection sub-lens 412 alone can meet the optical requirements of the projection system of the micro-projection module. The combined optical path correction of the first and second projection sub-lens 411 and 412 ensures that the projection optical path meets the effective focal length requirements of the overall system. It is understood that the first projection sub-lens 411 must cooperate with the second projection sub-lens 412 to meet the optical parameter requirements of both the projection system and the illumination system, allowing the optical path within the first projection sub-lens 411 to be reused by both the illumination and projection systems.

[0060] As shown in FIG1 , the combined-color illumination light emitted from the color combining device 13 passes through the light homogenizing device 14 and the polarizing device 15 in sequence along a first direction and is converted into polarized illumination light S. The polarized illumination light S turns 90° in the polarization beam splitting component 22 and reaches the display chip 30 along a second direction. After being modulated by the display chip 30 into polarized image light P', it returns 180° and is modulated along a third direction through the first projection sub-lens 411 and reaches the polarization beam splitting component 22 again. After being transmitted, it continues along the third direction to enter the second projection sub-lens 412. Finally, it is modulated by the first projection sub-lens 411 and the second projection sub-lens 412 into projection light, which is projected from the micro-projection module, forming a complete illumination light path and projection light path. The first direction and the second direction are perpendicular to each other, and the second direction and the third direction are parallel to and opposite to each other. The micro-projection module as a whole has an L-shaped structure.

[0061] It can be understood that in an optional embodiment, the complete projection lens is composed of two projection sub-lenses, at least one projection sub-lens is arranged between the polarization splitting component 22 and the display chip 30, and at least one other projection sub-lens is arranged on the other side of the polarization splitting component 22. Compared with the solution of arranging the complete projection lens on the same side of the polarization splitting component, the overall length direction of the optical machine is greatly reduced. Among them, the first projection sub-lens 411 is used for both the illumination light path and the convergence of the light, and the projection light path. While meeting the object-image relationship and image quality balance, it reduces the PBS prism size requirement, effectively utilizes the internal space of the optical machine, and folds the light path while meeting the total optical path requirement, reducing the overall volume; the second projection sub-lens 412 is used to balance the image quality and expand the light, so that the chip target image is projected out of the optical machine without loss, that is, the first projection sub-lens 41 and the second projection sub-lens 412 jointly meet the projection requirements of the optical system and complete the projection. The micro projection module provided by this application has obvious miniaturization advantages compared to the volume of traditional micro projection modules.

[0062] It is worth mentioning that in this application, the number and setting positions of the projection sub-lenses are not limited by the present invention. It is easy for those skilled in the art to split the projection lens into different numbers of projection sub-lenses and set them at different positions according to the optical design requirements of the projection system and the illumination system.

[0063] In addition to the aforementioned micro projection module optical system, the micro projection module further includes a power supply unit, a housing, structural connectors between the optical elements, and a heat dissipation unit.

[0064] The present invention also provides a head-mounted display device, comprising at least one micro-projection module as described above, at least one lens unit, a frame for mounting the lens unit and micro-projection module, temples for wearing the device, and a computing unit for processing data and image information, wherein the micro-projection module outputs images based on instructions issued by the computing unit. The following, using AR glasses as an example, provides an exemplary and detailed description of a head-mounted display device including the micro-projection module.

[0065] As shown in Figures 3A-3C, the AR glasses include a micro projection module 1, a frame 2 for mounting a lens unit, a left lens unit 3, a right lens unit 4, a computing unit 5, and temples 6 for wearing. Here, the left lens unit 3 and the right lens unit 4 are fixedly mounted in the frame 2, and the temples 6 can be connected to the frame 2 in any manner, such as in a flexible manner, or in the form of a folding leaf, or in a fixed manner, or in a detachable manner, thereby forming the main body of the AR glasses. The electronic components of the AR glasses can be selectively mounted on the temples 6 and / or the frame 2, or embedded / buried in their materials. The electronic components include but are not limited to a computing unit 5 for processing data and image information, an eye tracker, a depth sensor, a space sensor, a position sensor, and combinations thereof.

[0066] In an optional embodiment, there are two micro-projection modules 1, each mounted on a left or right temple 6 near the frame 2. Optionally, the micro-projection module is mounted on the inner side of the temple. When the micro-projection module 1 is mounted on the temple 6, the optical axis of the first projection sub-lens 411 is arranged along the extension direction of the temple 6, so that the optical axis of the second projection sub-lens 412 is approximately perpendicular to the lens unit. The left lens unit 3 includes an in-coupling region 31 and an out-coupling region 32. The in-coupling region 31 is located in the upper left corner of the left lens unit 3, and the optical axis of the second projection sub-lens 412 of the micro-projection module 1 is aligned with the center of the in-coupling region 31. The right lens unit 4 includes an in-coupling region 41 and an out-coupling region 42. The in-coupling region 41 is located in the upper right corner of the right lens unit 4, and the optical axis of the second projection sub-lens 412 of the micro-projection module 1 is aligned with the center of the in-coupling region 41. The image light projected by the micro-projection module 1 is coupled into the optical waveguide from the coupling-in area, and after turning and pupil expansion, it is coupled out from the coupling-out area and finally received by the user's eyes. The number of lenses of the first projection sub-lens 411 can be 3 to 6, and the number of lenses of the second projection sub-lens 412 can be 1 to 3. The number of lenses of the first projection sub-lens is preferably twice or more than the number of lenses of the second projection sub-lens, so that after assembly, the second projection sub-lens 412 does not protrude too much from the micro-projection module. The micro-projection module 1 as a whole is close to an L-shaped structure, with the long side of L corresponding to the first projection sub-lens part and the short side of L corresponding to the illumination light source part. From the side, the temples 6 and the frame 2 of the AR glasses also form an L-shaped structure, with the long side of L corresponding to the temples 6 and the short side of L corresponding to the frame 2. The shape of the micro-projection module 1 is compatible with the shape of the AR glasses. When the micro-projection module is installed on the temples in the above manner, it will not occupy too much other space of the AR glasses, giving the user a more comfortable wearing experience.

[0067] Similarly, in combination with the specific shape and spatial structure of the head-mounted display device, the shapes of other lens units, the setting positions of the coupling areas, and the setting positions of the micro-projection modules may also be considered, and the present invention does not impose any restrictions on this.

[0068] The above describes the basic principles, main features, and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above-described embodiments. The above-described embodiments and the specification merely illustrate the principles of the present application. Various changes and improvements may be made to the present application without departing from the spirit and scope of the present application. These changes and improvements fall within the scope of the present application for which protection is sought. The scope of protection claimed by the present application is defined by the appended claims and their equivalents.

Claims

1. A micro projection module, characterized in that: include: an illumination assembly configured to provide polarized illumination light; as well as, A display chip is configured to modulate the polarized illumination light into polarized image light; as well as a relay component configured to transmit the polarized illumination light to the display chip and transmit the polarized image light to the projection component, the relay component comprising a polarization beam splitter component; as well as A projection assembly is configured to project the polarized image light into an image, the projection assembly comprising a first projection sub-lens and a second projection sub-lens, wherein the first projection sub-lens is disposed in the optical path between the polarization beam splitting assembly and the display chip, and is configured to provide a transmission path for the polarized illumination light and the polarized image light and perform optical path correction, and the second projection sub-lens and the first projection sub-lens are disposed on opposite sides of the polarization beam splitting assembly, and the optical axes of the second projection sub-lens and the first projection sub-lens are co-linear.

2. The micro projection module according to claim 1, wherein: The number of lenses of the first projection sub-lens is twice or more than the number of lenses of the second projection sub-lens.

3. The micro projection module according to claim 1, wherein: The lighting assembly includes: an illumination light source configured to emit multiple monochromatic illumination lights; a collimating device; a color combining device; a light homogenizing device; and a polarizing device, wherein the collimating device and the color combining device are arranged in the optical path between the illumination light source and the polarizing device, and are configured to collimate the multiple monochromatic illumination lights into one combined-color illumination light, the optical path of the combined-color illumination light being perpendicular to the optical axis of the first projection sub-lens, and the polarizing device being configured to polarize the combined-color illumination light into the polarized illumination light.

4. The micro projection module according to claim 3, wherein: The polarizing device is a first polarizer, which is configured to pass polarized light with a first polarization state and block polarized light with a second polarization state. The polarization splitter component is configured to reflect polarized light with the first polarization state and transmit polarized light with the second polarization state, wherein the polarization directions of the first polarization state and the second polarization state are perpendicular to each other.

5. The micro projection module according to claim 1, wherein: The first projection sub-lens and the second projection sub-lens together meet the projection requirements of the optical system.

6. The micro projection module according to claim 1, wherein: The display chip is an LCoS chip.

7. A head-mounted display device, characterized in that: include: At least one micro-projection module according to any one of claims 1 to 6; as well as, At least one lens unit, a frame, two temples, and a computing unit; the micro projection module is arranged at the area where the temples are close to the frame.

8. The head-mounted display device according to claim 7, wherein: The optical axis of the first projection sub-lens is consistent with the extension direction of the temple.

9. The head mounted display device according to claim 7, wherein: The at least one lens unit is a light waveguide, including an incoupling area and an outcoupling area.

10. The head mounted display device according to claim 9, wherein: The optical axis of the second projection sub-lens is aligned with the center of the coupling-in area.

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