CN114063373A

CN114063373A - Micro projection light engine and wearable display device and method thereof

Info

Publication number: CN114063373A
Application number: CN202010770740.9A
Authority: CN
Inventors: 张倩; 陈杭; 胡增新
Original assignee: Sunny Optical Zhejiang Research Institute Co Ltd
Current assignee: Sunny Optical Zhejiang Research Institute Co Ltd
Priority date: 2020-08-04
Filing date: 2020-08-04
Publication date: 2022-02-18

Abstract

A micro projection light engine and a wearable display device and method thereof. The micro projection light engine comprises an illumination component, a display chip, an imaging component and a special-shaped polarization light splitting component. The display chip is used for modulating the polarized illumination light into polarized image light carrying image information. The imaging assembly has an imaging optical path for projecting the polarized image light along the imaging optical path. The special-shaped polarization light splitting component is provided with an incident surface corresponding to the illuminating component, a display surface corresponding to the display chip and an emergent surface corresponding to the imaging component, and an included angle between the emergent surface of the special-shaped polarization light splitting component and the display surface is an acute angle or an obtuse angle, so that the polarized illumination light from the illuminating component is transmitted to the display chip, the polarized image light from the display chip is transmitted to the imaging component, and the imaging light path of the imaging component is deviated or deviated from the display chip.

Description

Micro projection light engine and wearable display device and method thereof

Technical Field

The invention relates to the technical field of micro projection, in particular to a micro projection light engine, wearable display equipment and a method thereof.

Background

In recent years, as the micro-projection technology becomes mature, the micro-projection has already gone out of the concept stage and gradually goes into the stage of commercialization of the product, and more small portable projection media players, projection mobile phones, and wearable display devices (such as AR glasses) are coming into the market, so that the application mode of the micro-projection technology is more diversified and the development prospect is expected.

The micro-projection technology is usually developed based on micro-projection display chips, and the current mainstream micro-projection display chips include TFT-LCD, LCoS and DMD chips. But in these three display chips: firstly, the TFT-LCD chip-based light engine has low contrast, low light energy utilization rate, low brightness and low resolution; secondly, although the optical engine based on the DMD chip has higher contrast and light energy utilization rate, the physical resolution ratio in the current small-size field is lower than that of the LCoS, and meanwhile, the price is very high due to the fact that the optical engine is an exclusive technology; finally, the optical engine based on the LCoS chip has good physical resolution and light energy utilization rate, and meanwhile, in view of mature technology and good quality of the LCoS, the price of the LCoS chip is also an obvious advantage even compared with a DMD chip. Therefore, in summary, the LCoS chip is more cost effective among the three chips. In addition, for the projection optical machine in the AR application field, since most waveguides need polarized light to be coupled in, and the LCoS chip itself is a polarized light modulation device, the LCoS chip also has a congenital advantage in this respect.

However, the challenge of the current micro-projection light engine is mainly the volume and weight of the light engine, and particularly, the conventional PBS beam splitter prism is generally adopted by most LCoS projection light engines matching with the waveguide, so that the imaging optical path of the imaging lens of the existing projection light engine is generally parallel to the LCoS chip, which results in that the conventional PBS beam splitter prism in the existing projection light engine needs to have a large enough size to match with the LCoS chip and the imaging lens, and further causes the volume and weight of the existing projection light engine to be large.

Meanwhile, in order to avoid the structural interference when the imaging lens of the projection light engine is matched with the waveguide, a coupling-out prism with a larger size is usually correspondingly arranged between the imaging lens of the projection light engine and the waveguide. The increased size of the coupling-out prism not only increases the design pressure of the imaging lens, but also causes the overall weight and volume of the light engine to be further increased, so that the existing projection light engine cannot meet the requirements of wearable display equipment such as AR glasses and VR glasses on the small volume and light weight of the light engine, and cannot meet the miniaturization fighting trend of electronic equipment, and the existing projection light engine is not beneficial to being widely applied and popularized in the wearable fields such as augmented reality, virtual reality and near-eye display.

Disclosure of Invention

An advantage of the present invention is to provide a micro projection light engine and a wearable display device and method thereof, which can meet the market demand for a small-sized, light-weight micro projection light engine.

Another advantage of the present invention is to provide a micro projection light engine and a wearable display device and a method thereof, wherein in an embodiment of the present invention, the micro projection light engine uses a special-shaped polarization beam splitter to replace a conventional PBS beam splitter prism, which helps to make the structure of the micro projection light engine ultra-compact, thereby greatly reducing the volume of the micro projection light engine.

Another advantage of the present invention is to provide a micro projection light engine and a wearable display device and a method thereof, wherein, in an embodiment of the present invention, the profiled polarization beam splitter assembly of the micro projection light engine can make an included angle between an imaging light path and a display chip be an acute angle or an obtuse angle, which not only can reduce the volume and weight of a beam splitter prism, but also can directly utilize a coupling-out prism with smaller volume and weight to avoid structural interference.

Another advantage of the present invention is to provide a micro projection light engine and a wearable display device and method thereof, wherein in an embodiment of the present invention, the overall size of the micro projection light engine is small enough and portable, and the micro projection light engine is suitable for application and popularization in wearable fields such as augmented reality, virtual reality, and near-to-eye display.

Another advantage of the present invention is to provide a micro projection light engine and a wearable display device and a method thereof, wherein in an embodiment of the present invention, the micro projection light engine is adapted to project polarized light carrying image information into a waveguide of the wearable display device to project the polarized light carrying image information into a human eye for imaging through the waveguide.

Another advantage of the present invention is to provide a micro projection light engine, a wearable display device and a method thereof, wherein in an embodiment of the present invention, the micro projection light engine can flexibly adjust an included angle between an imaging light path and a display chip through the special-shaped polarization beam splitter, so that an outcoupling surface of an outcoupling prism moves outward, and structural interference is avoided. Meanwhile, the overall height of the miniature projection light engine can be compressed to a certain extent, so that the structure of the whole light engine is more compact, and the reduction of the volume and the weight of the light engine is facilitated.

Another advantage of the present invention is to provide a micro projection light engine and a wearable display device and method thereof, wherein in an embodiment of the present invention, the micro projection light engine can still ensure that the display chip and the coupling-out surface of the coupling-out prism are kept parallel, which helps to avoid increasing the design difficulty of the optical structure.

Another advantage of the present invention is to provide a micro projection light engine, a wearable display device and a method thereof, wherein in an embodiment of the present invention, the special-shaped polarization beam splitter of the micro projection light engine can separate an illumination light path from an imaging light path by a certain angle, so as to ensure that an inclination angle of the imaging light path can be adjusted as needed, and simultaneously, an arrangement angle of the illumination light path can be flexibly adjusted, so that the whole light path and the structural layout are more reasonable.

Another advantage of the present invention is to provide a micro projection light engine and a wearable display apparatus and method thereof, wherein expensive materials or complicated structures are not required in the present invention in order to achieve the above objects. Accordingly, the present invention successfully and efficiently provides a solution that not only provides a simple micro projection light engine and wearable display device and method thereof, but also increases the practicality and reliability of the micro projection light engine and wearable display device and method thereof.

To achieve at least one of the above advantages or other advantages and objects, the present invention provides a micro projection light engine, comprising:

an illumination assembly, wherein the illumination assembly has an illumination light path for emitting polarized illumination light having the same polarization state along the illumination light path;

the display chip is used for modulating the polarized illumination light into polarized image light carrying image information;

an imaging assembly, wherein said imaging assembly has an imaging optical path for projecting the polarized image light along said imaging optical path; and

the special-shaped polarization light splitting assembly is provided with an incident surface corresponding to the illuminating assembly, a display surface corresponding to the display chip and an exit surface corresponding to the imaging assembly, and an included angle between the exit surface of the special-shaped polarization light splitting assembly and the display surface is an acute angle or an obtuse angle, so that the polarized illumination light from the illuminating assembly is transmitted to the display chip, the polarized image light from the display chip is transmitted to the imaging assembly, and the imaging light path of the imaging assembly is deflected or deviated from the display chip.

According to an embodiment of the present invention, the special-shaped polarization beam splitter assembly includes a first prism, a second prism, and at least one polarization beam splitter element, wherein a first inclined surface of the first prism and a second inclined surface of the second prism are oppositely disposed, and the at least one polarization beam splitter element is disposed between the first inclined surface of the first prism and the second inclined surface of the second prism, wherein a first side surface of the first prism serves as the incident surface of the special-shaped polarization beam splitter assembly, and two second side surfaces of the second prism respectively serve as the exit surface and the display surface of the special-shaped polarization beam splitter assembly.

According to an embodiment of the present invention, the second prism is a prism with an acute or obtuse vertex angle

According to an embodiment of the present invention, the first prism is a prism whose vertex angle is an acute angle or an obtuse angle, and the exit surface of the special-shaped polarization beam splitter assembly is parallel to the incident surface of the special-shaped polarization beam splitter assembly.

According to an embodiment of the present invention, the special-shaped polarization beam splitter further includes a polarization folding back component, and the special-shaped polarization beam splitter further has a folding back surface corresponding to the polarization folding back component, wherein the polarization folding back component is configured to reflect the polarized light with the first polarization state input from the folding back surface, and convert the polarized light with the first polarization state into the polarized light with the second polarization state incident from the folding back surface.

According to an embodiment of the present invention, the other first side surface of the first prism serves as the folding surface of the special-shaped polarization beam splitter, and the folding surface of the special-shaped polarization beam splitter is parallel to the display surface of the special-shaped polarization beam splitter.

According to an embodiment of the present invention, the special-shaped polarization beam splitter assembly includes a first prism, a second prism, and at least one polarization beam splitter element, wherein a first inclined surface of the first prism and a second inclined surface of the second prism are oppositely disposed, and the at least one polarization beam splitter element is disposed between the first inclined surface of the first prism and the second inclined surface of the second prism, wherein two first side surfaces of the first prism serve as the incident surface and the display surface of the special-shaped polarization beam splitter assembly, and a second side surface of the second prism respectively serves as the exit surface of the special-shaped polarization beam splitter assembly.

According to an embodiment of the present invention, the special-shaped polarization splitting assembly further includes a wedge prism, and the wedge prism is disposed between the first inclined plane of the first prism and the second inclined plane of the second prism, respectively, wherein the at least one polarization splitting element includes a first polarization splitting element and a second polarization splitting element, wherein the first polarization splitting element is disposed between the first inclined plane of the first prism and the wedge prism, and the second polarization splitting element is disposed between the second inclined plane of the second prism and the wedge prism.

According to an embodiment of the invention, the polarization splitting element is a dielectric film stack, a PBS film or an WGF wire grid film.

According to an embodiment of the present invention, the illumination assembly includes an illumination light source, a collimated color combination assembly and a polarization device, wherein the illumination light source is configured to emit multiple monochromatic illumination lights, the collimated color combination assembly is disposed between the illumination light source and the polarization device, and is configured to collimates the multiple monochromatic illumination lights from the illumination light source into a combined color illumination light propagating along the illumination light path, and the polarization device is configured to convert the combined color illumination light into the polarized illumination light having the same polarization state.

According to an embodiment of the invention, the illumination light source is an RGB three-in-one light source, a light source composed of an RB two-in-one light source and a G light source, or an L-shaped LED light source.

According to an embodiment of the present invention, the illumination assembly further includes a light uniformizing device, wherein the light uniformizing device is disposed between the collimating and color combining assembly and the polarizing device, and is configured to perform a light uniformizing process on the combined color illumination light from the collimating and color combining assembly.

According to an embodiment of the present invention, the display chip is an LCoS chip.

According to another aspect of the present invention, there is further provided a micro projection light engine, comprising:

the special-shaped polarization light splitting assembly is provided with an incident surface corresponding to the illuminating assembly, a display surface corresponding to the display chip and an emergent surface corresponding to the imaging assembly, and is used for transmitting the polarized illumination light from the illuminating assembly to the display chip and transmitting the polarized image light from the display chip to the imaging assembly; wherein the profiled polarization splitting assembly includes a first prism for providing the incident surface, a second prism for providing the exit surface, a wedge prism, and a first and second polarization splitting elements, and the wedge prisms are disposed between a first inclined surface of the first prism and a second inclined surface of the second prism, respectively, wherein the first polarization splitting element is disposed between the first inclined surface of the first prism and the wedge prism, and the second polarization splitting element is disposed between the second inclined surface of the second prism and the wedge prism.

According to an embodiment of the present invention, the second prism is a prism whose vertex angle is a right angle.

According to another aspect of the present invention, there is further provided a wearable display apparatus comprising:

a micro projection light engine, wherein the micro projection light engine comprises:

the special-shaped polarization light splitting assembly is provided with an incident surface corresponding to the illuminating assembly, a display surface corresponding to the display chip and an exit surface corresponding to the imaging assembly, and an included angle between the exit surface of the special-shaped polarization light splitting assembly and the display surface is an acute angle or an obtuse angle, so that the polarized illumination light from the illuminating assembly is transmitted to the display chip, the polarized image light from the display chip is transmitted to the imaging assembly, and the imaging light path of the imaging assembly is deflected or deviated from the display chip;

a waveguide; and

an outcoupling prism, wherein the outcoupling prism is disposed between the micro projection light engine and the waveguide, for coupling the polarized image light from the micro projection light engine into the waveguide to display the polarized image light as an image through the waveguide.

According to an embodiment of the present invention, the coupling-out surface of the coupling-out prism is parallel to the display surface of the special-shaped polarization splitting component.

the special-shaped polarization light splitting assembly is provided with an incident surface corresponding to the illuminating assembly, a display surface corresponding to the display chip and an emergent surface corresponding to the imaging assembly, and is used for transmitting the polarized illumination light from the illuminating assembly to the display chip and transmitting the polarized image light from the display chip to the imaging assembly; wherein the profiled polarization splitting assembly comprises a first prism for providing the incident surface, a second prism for providing the exit surface, a wedge prism, and a first and second polarization splitting elements, and the wedge prisms are disposed between a first inclined surface of the first prism and a second inclined surface of the second prism, respectively, wherein the first polarization splitting element is disposed between the first inclined surface of the first prism and the wedge prism, and the second polarization splitting element is disposed between the second inclined surface of the second prism and the wedge prism;

a waveguide; and

According to another aspect of the present invention, the present invention further provides a projection method of a micro projection light engine, comprising the steps of:

emitting polarized illumination light with a first polarization state to an incident surface of a special-shaped polarization light splitting component along an illumination light path;

transmitting the polarized illumination light with the first polarization state incident from the incidence surface to a display surface of the special-shaped polarization light splitting assembly, and converting the polarized illumination light with the first polarization state into polarized illumination light with a second polarization state;

modulating the polarized illumination light having the second polarization state emitted from the display surface into polarized image light having a first polarization state;

the polarized image light with the first polarization state, which is incident from the display surface, is reflected to an emergent surface of the special-shaped polarization light splitting component in a bending mode, wherein an included angle between the emergent surface and the display surface is an acute angle or an obtuse angle; and

projecting the polarized image light with the first polarization state emitted from the emergent surface along an imaging optical path to form an image.

According to an embodiment of the present invention, the step of transmitting the polarized illumination light with the first polarization state incident from the incident surface to a display surface of the special-shaped polarization beam splitter, and converting the polarized illumination light with the first polarization state into polarized illumination light with the second polarization state includes the steps of:

the polarized illumination light with the first polarization state incident from the incident surface is reflected to a refraction surface of the special-shaped polarization light splitting component in a bending mode;

reflecting the polarized illumination light with the first polarization state emitted from the folding surface in a folding manner, so that the polarized illumination light with the first polarization state is converted into polarized illumination light with a second polarization state after passing through a light conversion element twice; and

and transmitting the polarized illumination light with the second polarization state incident from the turn-back surface to the display surface of the special-shaped polarization light splitting component.

Further objects and advantages of the invention will be fully apparent from the ensuing description and drawings.

These and other objects, features and advantages of the present invention will become more fully apparent from the following detailed description, the accompanying drawings and the claims.

Drawings

Fig. 1 is a system schematic diagram of a wearable display device according to an embodiment of the invention.

Fig. 2 is a schematic structural diagram of a micro projection light engine of the wearable display device according to the above embodiment of the invention.

FIG. 3 is a schematic diagram of the optical path of the micro projection light engine according to the above-described embodiment of the present invention.

FIG. 4 illustrates a first variant implementation of the micro-projection light engine according to the above-described embodiment of the invention.

FIG. 5 illustrates a second variant implementation of the micro-projection light engine according to the above-described embodiment of the invention.

FIG. 6 illustrates a third variant implementation of the micro-projection light engine according to the above-described embodiment of the invention.

FIG. 7 illustrates a schematic optical path diagram of a micro projection light engine, according to another embodiment of the present invention.

Fig. 8A and 8B are schematic flow diagrams of a projection method of a micro projection light engine according to an embodiment of the invention.

Detailed Description

The following description is presented to disclose the invention so as to enable any person skilled in the art to practice the invention. The preferred embodiments in the following description are given by way of example only, and other obvious variations will occur to those skilled in the art. The basic principles of the invention, as defined in the following description, may be applied to other embodiments, variations, modifications, equivalents, and other technical solutions without departing from the spirit and scope of the invention.

It will be understood by those skilled in the art that in the present disclosure, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in an orientation or positional relationship indicated in the drawings for ease of description and simplicity of description, and do not indicate or imply that the referenced devices or components must be constructed and operated in a particular orientation and thus are not to be considered limiting.

In the present invention, the terms "a" and "an" in the claims and the description should be understood as meaning "one or more", that is, one element may be one in number in one embodiment, and the element may be more than one in number in another embodiment. The terms "a" and "an" should not be construed as limiting the number unless the number of such elements is explicitly recited as one in the present disclosure, but rather the terms "a" and "an" should not be construed as being limited to only one of the number.

In the description of the present invention, it is to be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. In the description of the present invention, it should be noted that, unless explicitly stated or limited otherwise, the terms "connected" and "connected" are to be interpreted broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

In recent years, with the advent of micro display chip technology, miniaturization and high-resolution projection display have become possible. However, the conventional micro projection light engine cannot meet the strict requirements of wearable products such as augmented reality, virtual reality, near-eye display and the like on volume and weight due to the fact that the conventional PBS beam splitter prism (i.e., the conventional polarization beam splitter prism composed of two right-angle prisms and one polarization beam splitter) is large in volume and heavy in weight. In particular, when the existing micro projection light engine is matched with the waveguide to assemble the wearable display device, in order to avoid the structural interference between the light engine and the waveguide, a coupling-out prism with a sufficient size is usually required to be arranged between the existing micro projection light engine and the waveguide, which further increases the volume and weight of the wearable display device, and makes it more difficult to meet the strict volume and weight requirements of the wearable product. Therefore, a miniature projection light engine with small enough volume and light weight is needed to meet the market demand.

Referring to fig. 1-3 of the drawings, a miniature projection light engine according to one embodiment of the present invention is illustrated. Specifically, the micro projection light engine 1 includes an illumination assembly 10, a display chip 20, an imaging assembly 30, and a polarization beam splitter assembly 40. The illumination assembly 10 has an illumination light path 100 for emitting polarized illumination light having the same polarization state along the illumination light path 100. The display chip 20 is configured to modulate the polarized illumination light into polarized image light carrying image information. The imaging assembly 30 has an imaging optical path 300 for projecting the polarized image light along the imaging optical path 300. The special-shaped polarization beam splitter 40 has an incident surface 401 corresponding to the illumination assembly 10, a display surface 402 corresponding to the display chip 20, and an exit surface 403 corresponding to the imaging assembly 30, and an included angle γ between the exit surface 403 of the special-shaped polarization beam splitter 40 and the display surface 402 is an acute angle or an obtuse angle, so as to transmit the polarized illumination light from the illumination assembly 10 to the display chip 20 and transmit the polarized image light from the display chip 20 to the imaging assembly 30, so that the imaging optical path 300 of the imaging assembly 30 is deflected or deviated from the display chip 20.

In other words, the shaped polarization beam splitter 40 is disposed between the illumination module 10, the display chip 20, and the imaging module 30, and the incident surface 401, the display surface 402, and the exit surface 403 of the shaped polarization beam splitter 40 correspond to the illumination module 10, the display chip 20, and the imaging module 30, respectively.

It should be noted that, since the included angle γ between the display surface 402 and the exit surface 403 of the special-shaped polarization beam splitter 40 of the micro projection light engine 1 of the present invention is an acute angle or an obtuse angle (i.e. a non-right angle), a non-zero included angle exists between the imaging light path 300 of the imaging component 30 corresponding to the exit surface 403 and the display chip 20 corresponding to the display surface 402, that is, the imaging light path 300 and the display chip 20 are not parallel to each other, so that the imaging light path 300 will be deviated or deviated from the display chip 20. In other words, the projection end of the imaging component 30 of the micro projection light engine 1 is biased or deviated from the display chip 20, so that, as shown in fig. 1, when the micro projection light engine 1 is required to provide image light for the waveguide 50 of the wearable display device, the coupling-out surface 601 of the coupling-out prism 60 disposed between the imaging component 30 and the waveguide 50 is moved outwards, and therefore, even if the size of the coupling-out prism 60 is reduced, the structural interference between the micro projection light engine 1 and the waveguide 50 can be avoided, which helps to make the structure of the wearable display device more compact so as to reduce the volume and weight of the wearable display device.

More specifically, as shown in fig. 2 and 3, the special-shaped polarization beam splitter assembly 40 of the micro projection light engine 1 may include but is not limited to a first prism 41, a second prism 42 and at least one polarization beam splitter element 43, wherein the first slope 411 of the first prism 41 and the second slope 421 of the second prism 42 are oppositely disposed, and the polarization splitting element 43 is disposed between the first slope 411 of the first prism 41 and the second slope 421 of the second prism 42, wherein a first side surface 412 of the first prism 41 is used as the incident surface 401, and two second side surfaces 422 of the second prism 42 are respectively used as the emergent surface 403 and the display surface 402, wherein the polarization splitting element 43 is configured to reflect the polarized light having the first polarization state and transmit the polarized light having the second polarization state.

Preferably, the polarization beam splitter 43 can be implemented as, but not limited to, a PBS film for reflecting polarized light having S polarization (S light for short) and transmitting polarized light having P polarization (P light for short). For example, the polarization beam splitting element 43 may be implemented as, but not limited to, a PBS dielectric film stack plated on the optical surface or a 3M-PBS film glued on the optical surface. Of course, in other examples of the present invention, the polarization beam splitting element 43 can also be implemented as an WGF wire grid (english: wire-drawing film; chinese: metal wire grid film), and still achieve the polarization beam splitting effect. It is to be understood that, in order to distinguish between polarized illumination light and polarized image light, in the drawings of the present invention, S and S denote polarized illumination light and polarized image light having an S polarization state, respectively; p and P denote polarized illumination light and polarized image light, respectively, having a P polarization state; and unpolarized light (which may be primary or combined color light, etc.) is denoted by S + P.

More preferably, the polarization beam splitter 43 may be plated on the first inclined surface 411 of the first prism 41 or the second inclined surface 421 of the second prism 42, and correspondingly, the first inclined surface 411 of the first prism 41 and the second inclined surface 421 of the second prism 42 are glued to each other, so that the polarization beam splitter 43 is located between the first inclined surface 411 of the first prism 41 and the second inclined surface 421 of the second prism 42. Of course, in other examples of the present invention, the polarization splitting element 43 may also be directly glued between the first inclined surface 411 of the first prism 41 and the second inclined surface 421 of the second prism 42.

It is worth mentioning that, limited by the size limitations of the display chip 20 and the imaging assembly 30, the second prism 42 of the shaped polarization beam splitter assembly 40 needs to provide the display surface 402 and the exit surface 403 with a large enough area to match the display chip 20 and the imaging assembly 30, that is, the second side surface 422 of the second prism 42 of the shaped polarization beam splitter assembly 40 needs to have a large enough area to meet the size requirements of the display chip 20 and the imaging assembly 30. Since the included angle γ between the exit surface 403 of the special-shaped polarization beam splitter 40 and the display surface 402 of the micro projection light engine 1 of the present invention is an acute angle or an obtuse angle (i.e. a non-right angle), when the size requirement of the display chip 20 and the imaging assembly 30 is fixed, the more the included angle γ between the exit surface 403 and the display surface 402 is away from the right angle, the smaller the volume and weight of the second prism 42 are. It can be understood that when the size requirement of the display chip 20 and the imaging assembly 30 is fixed, that is, the area of the exit surface 403 and the display surface 402 is fixed, and the included angle between the exit surface 403 and the display surface 402 is a right angle (such as a conventional PBS splitting prism), the volume of the second prism 42 is maximized, and thus the weight of the second prism 42 is maximized.

In other words, since the included angle γ between the exit surface 403 of the special-shaped polarization beam splitter 40 of the micro projection light engine 1 and the display surface 402 is an acute angle or an obtuse angle, the volume and the weight of the second prism 42 of the special-shaped polarization beam splitter 40 of the invention are reduced, and further the volume and the weight of the micro projection light engine 1 of the invention are smaller than those of the existing micro projection light engine, so that the micro projection light engine 1 of the invention can meet the requirements of miniaturization and light weight of a portable display device.

Exemplarily, in the above embodiment of the present invention, as shown in fig. 1, the second prism 42 of the special-shaped polarization beam splitter assembly 40 may be implemented as a prism with an obtuse vertex angle (i.e., an obtuse-angle prism), that is, the included angle γ between the exit surface 403 of the special-shaped polarization beam splitter assembly 40 and the display surface 402 is an obtuse angle, so that the imaging optical path 300 of the imaging assembly 30 is deviated toward the display chip 20, which helps to move the coupling-out surface 601 of the coupling-out prism 60 outward toward the direction close to the display chip 20, and helps to avoid the occurrence of structural interference when the volume and weight of the coupling-out prism 60 are reduced.

Correspondingly, the first prism 41 of the shaped polarization beam splitter assembly 40 may also be implemented as an obtuse prism, and the size and shape of the first prism 41 and the second prism 42 preferably remain the same, so that the shaped polarization beam splitter assembly 40 having a parallelogram structure is assembled by the first prism 41 and the second prism 42. In other words, in the above-mentioned embodiment of the present invention, the incident surface 401 of the special-shaped polarization splitting assembly 40 is parallel to the exit surface 403 of the special-shaped polarization splitting assembly 40.

It should be noted that, since polarized illumination light generally needs to enter the special-shaped polarization beam splitter assembly 40 in a direction perpendicular to the incident surface 401, and polarized image light needs to exit the special-shaped polarization beam splitter assembly 40 in a direction perpendicular to the exit surface 403, in the above embodiment of the present invention, the directions of the illumination optical path 100 of the illumination assembly 10 of the micro projection light engine 1 and the imaging optical path 300 of the imaging assembly 30 are kept consistent, which helps to reduce the assembly difficulty of the micro projection light engine 1.

Preferably, the first prism 41 and the second prism 42 are both implemented as isosceles prisms, that is, the two base angles α and β of the second prism 42 are equal (i.e., α ═ β). Meanwhile, when the center distance between the display chip 20 and the coupling-out prism 60 is denoted by L, and the actually required offset distance of the coupling-out prism 60 is denoted by h, the included angle θ between the imaging optical path 300 of the imaging component 30 and the display chip 20 satisfies the following relationship: tan theta is h/L; and the two base angles α and β of the second prism 42 satisfy the following relationships, respectively: α ═ β ═ 90 ° - θ)/2.

According to the above embodiment of the present invention, as shown in fig. 2 and fig. 3, the special-shaped polarization beam splitter 40 of the micro projection light engine 1 may further include a polarization folding assembly 44, and the special-shaped polarization beam splitter 40 has a folding surface 404 corresponding to the polarization folding assembly 44, wherein the polarization folding assembly 40 is configured to reflect the polarized light with the first polarization state (e.g., S light) emitted through the folding surface 404 and convert the polarized light with the first polarization state (e.g., S light) into the polarized light with the second polarization state (e.g., P light) emitted through the folding surface 404.

It should be noted that the two first side surfaces 412 of the first prism 41 of the special-shaped polarization beam splitter assembly 40 are respectively used as the incident surface 401 and the turning surface 404. Correspondingly, the folding surface 404 of the special-shaped polarization beam splitter assembly 40 is substantially parallel to the display surface 402 of the special-shaped polarization beam splitter assembly 40.

For example, as shown in fig. 2 and 3, the polarization folding-back assembly 44 of the special-shaped polarization splitting assembly 40 may include a light conversion element 441 and a light reflection element 442, wherein the light conversion element 441 is disposed between the light reflection element 442 and the folding-back surface 44. The light reflection element 442 is configured to reflect the polarized light with the first polarization state emitted from the light conversion element 441 back to the light conversion element 441, so that the polarized light with the first polarization state passes through the light conversion element 441 twice. The light conversion element 441 is used to convert the polarized light having the first polarization state passing through twice into the polarized light having the second polarization state.

It is noted that, in the embodiment of the present invention, the light conversion element 441 can be implemented as, but not limited to, an 1/4 wave plate; the light reflecting element 442 may be, but is not limited to being, implemented as a concave mirror. Of course, in other examples of the present invention, the light conversion element 441 may be implemented as another type of wave plate or light conversion element as long as the polarized light passing twice can be converted into a polarization state; the light reflection element 442 may be implemented as another type of mirror or light reflection member, as long as the polarized light emitted from the folding surface 404 can be reflected back to the folding surface 404, so that the polarized light passes through the light conversion element 441 twice, and the invention is not limited thereto.

According to the above-described embodiment of the present invention, the display chip 20 of the micro-projection light engine 1 is preferably implemented as an LCoS chip 21, wherein the LCoS chip 21 is configured to modulate polarized illumination light (e.g., P-light) having a second polarization state into polarized image light (e.g., S-light) having the second polarization state.

Thus, as shown in fig. 2 and 3, when the illumination assembly 10 provides S light along the illumination light path 100, the S light enters the first prism 41 from the incident surface 401, and is reflected by the polarization beam splitter 43 to exit the first prism 41 from the reflection surface 404; next, after passing through the light conversion element 441 of the polarization folding assembly 44 for the first time, the S light is reflected by the light reflection element 442 of the polarization folding assembly 44 to pass through the light conversion element 441 again to form P light, and finally the P light is incident on the first prism 41 from the folding surface 404; then, the P light passes through the polarization beam splitter 43 to exit the second prism 42 from the display surface 402, and is modulated into S light by the LCoS chip 21 to enter the second prism 42 from the display surface 402; finally, the S light is reflected by the polarization beam splitter 43 to exit from the exit surface 403, and is projected along the imaging optical path 300 of the imaging component 30 for imaging. In addition, the S light propagating along the imaging optical path 300 can be totally reflected by the outcoupling prism 60 to be outcoupled from the outcoupling surface 601 of the outcoupling prism 60, and then the S light enters the waveguide 50 to display an image at the human eye through the propagation of the waveguide 50.

It is noted that, in the present invention, as shown in fig. 3, the polarized illumination light with the same polarization state emitted by the illumination assembly 10 is implemented as S light, and the polarized image light carrying the image information is correspondingly implemented as S light. Of course, in other examples of the present invention, the polarized illumination light with the same polarization state emitted by the illumination assembly 10 may also be implemented as P light, and the polarized image light carrying the image information is correspondingly implemented as P × light.

Since the conventional LED illumination light source is usually a monochromatic light source for emitting monochromatic illumination light, in order to ensure that the micro projection light engine 1 can project a color image, the polarized light emitted by the illumination assembly 10 of the micro projection light engine 1 must be a combined color illumination light (referred to as a combined color polarized light) having the same polarization state. Specifically, as shown in fig. 3 and 4, the illumination assembly 10 includes an illumination light source 11, a collimated color combination assembly 12, and a polarization device 13, wherein the illumination light source 11 is configured to emit multiple single-color illumination lights (e.g., S + P lights), the collimated color combination assembly 12 is disposed between the illumination light source 11 and the polarization device 13, and is configured to collimate the multiple single-color illumination lights from the illumination light source 11 into a combined-color illumination light propagating along the illumination light path 100, and the polarization device 13 is configured to convert the combined-color illumination light into the polarized illumination light (e.g., S light) having the same polarization state.

Preferably, the polarizing device 13 of the illumination assembly 10 may be, but is not limited to be, implemented as an S-polarizer, and the S-polarizer is adapted to be disposed adjacent to the incident plane 401 of the profiled polarizing beam splitting assembly 40, wherein the S-polarizer is configured to allow only S-light to pass through and block P-light or/and other parasitic light from passing through. For example, the S-polarizer is attached to the incident surface 401 of the special-shaped polarization splitting assembly 40, so that the combined-color polarized light obtained by polarization of the S-polarizer can be directly incident on the special-shaped polarization splitting assembly 40 from the incident surface 401.

Exemplarily, the illumination light source 11 of the illumination assembly 10 may be implemented as a RGB three-in-one light source for emitting red illumination light, green illumination light, and blue illumination light. Correspondingly, as shown in fig. 2, the collimating and color-combining component 12 may include a collimating lens group 121 and a color-combining component 122, and the collimating lens group 121 is disposed between the illumination light source 11 and the color-combining component 122, where the collimating lens group 121 is configured to collimate three paths of monochromatic illumination lights (e.g., R light, G light, and B light) emitted by the illumination light source 11, and the color-combining component 122 is configured to combine the collimated three paths of monochromatic illumination lights into one path of combined color illumination light. It is understood that, in other examples of the present invention, the illumination light source 11 may also be implemented as a light source composed of an RB two-in-one light source and a G light source, or the illumination light source 11 may also be implemented as an LED light source arranged in an L shape. Of course, the structure and type of the color combining assembly 122 can be selected according to the selected form of the illumination light source, for example, when RGB three-in-one light source is selected, the color combining assembly 122 can be implemented as, but not limited to, a color combining device composed of a wedge-shaped substrate and a selective reflection film system.

More specifically, as shown in fig. 2, the lighting assembly 10 may further include a light uniformizing device 14, wherein the light uniformizing device 14 is disposed between the collimated color combining assembly 12 and the polarizing device 13, and is configured to perform a light uniformizing process on the color combined illumination light from the collimated color combining assembly 12, so that the color combined illumination light from the collimated color combining assembly 12 is first subjected to a light uniformizing process by the light uniformizing device 14, and then subjected to a polarizing process by the polarizing device 13.

Preferably, the dodging device 14 can be implemented as, but not limited to, a fly-eye lens, so as to perform dodging processing on the combined color illumination light synthesized by the collimating and color-combining assembly 12 through the fly-eye lens, which helps to improve the uniformity of the combined color illumination light.

Further, as shown in fig. 2, the illumination assembly 10 may further include a relay lens 15, wherein the relay lens 15 is disposed between the light unifying device 14 and the polarizing device 13, and is used for adjusting the degree of convergence of the color combination illumination light homogenized by the light unifying device 14, so that the subsequent color combination polarized light satisfies the illumination area required by the display chip 20.

It should be noted that, as shown in fig. 2, the imaging component 30 of the micro projection light engine 1 of the present invention includes an imaging lens group for magnifying and imaging the polarized image light from the special-shaped polarization beam splitter component 40 to project an image with high imaging quality.

Preferably, as shown in fig. 2, the imaging lens group of the imaging assembly 30 includes at least one aspheric lens 31, which helps to shorten the size of the imaging assembly 30 and further reduce the volume of the micro projection light engine 1 while ensuring the imaging quality. Of course, in other examples of the present invention, the imaging assembly 30 of the micro-projection light engine 1 may also be implemented as any other type of imaging system as long as it is ensured that the imaging assembly 30 can project the polarized image light, and the present invention is not limited thereto.

Fig. 4 shows a first variant of the miniature projection light engine 1 according to the above-described embodiment of the invention. Compared to the above-described embodiment according to the invention, the first variant embodiment according to the invention differs in that: the second prism 42 of the special-shaped polarization beam splitter assembly 40 of the micro projection light engine 1 may be implemented as a prism with an acute vertex angle (i.e. an acute-angled prism), that is, the included angle γ between the exit surface 403 of the special-shaped polarization beam splitter assembly 40 and the display surface 402 is an acute angle, so that the imaging optical path 300 of the imaging assembly 30 deviates from the display chip 20, which helps to move the coupling-out surface 601 of the coupling-out prism 60 outwards away from the display chip 20, and can still help to avoid structural interference when reducing the volume and weight of the coupling-out prism 60.

It is noted that in this variant embodiment of the present invention, where L represents the center distance between the display chip 20 and the coupling-out prism 60, and h represents the actually required offset distance of the coupling-out prism 60, the included angle θ between the imaging optical path 300 of the imaging assembly 30 and the display chip 20 satisfies the following relationship: tan theta is h/L; and the two base angles α and β of the second prism 42 satisfy the following relationships, respectively: α ═ β ═ 90 ° + θ)/2.

Fig. 5 shows a second variant of the miniature projection light engine 1 according to the above-described embodiment of the present invention. Compared to the above-described example according to the invention, the second variant according to the invention differs in that: the two second side surfaces 422 of the second prism 42 of the special-shaped polarization beam splitter assembly 40 of the micro projection light engine 1 are respectively used as the emergent surface 403 and the return surface 404; correspondingly, the two first side surfaces 412 of the first prism 41 of the special-shaped polarization beam splitting assembly 40 are respectively used as the incident surface 401 and the display surface 402. It is understood that in this variant embodiment of the present invention, the included angle between the exit surface 403 of the special-shaped polarization splitting assembly 40 and the display surface 402 is still kept at an obtuse angle or an acute angle, which still enables the imaging optical path 300 of the imaging assembly 30 to deviate from the display chip 20, facilitates the outward movement of the coupling-out surface 601 of the coupling-out prism 60 away from the display chip 20, and still facilitates the avoidance of structural interference when reducing the volume and weight of the coupling-out prism 60.

It should be noted that, as shown in fig. 5, when the illumination assembly 10 provides S light, the S light entering the first prism 41 from the incident surface 401 will be reflected by the polarization beam splitting element 43 to exit from the display surface 402, and after being modulated into P light by the LCoS chip 21, the P light will enter the first prism 41 from the display surface 402; then, after passing through the polarization beam splitter 43 to exit the second prism 42 from the folding surface 404, the P-ray first passes through the light conversion element 441, and is reflected by the light reflection element 442 to pass through the light conversion element 441 again to form S-ray; finally, the S light enters the first prism 41 from the folding surface 404, and exits from the exit surface 403 after being reflected by the polarization beam splitter 43, so as to project an image along the imaging optical path 300 of the imaging component 30.

Fig. 6 shows a third variant of the miniature projection light engine 1 according to the above-described embodiment of the present invention. Compared to the above-described example according to the invention, the third variant according to the invention differs in that: the special-shaped polarization beam splitting assembly 40 of the micro projection light engine 1 may further include a wedge prism 45, wherein the wedge prism 45 is correspondingly disposed between the first inclined plane 411 of the first prism 41 and the second inclined plane 421 of the second prism 42, wherein the at least one polarization beam splitting element 43 includes two polarization beam splitting elements 43, and the two polarization beam splitting elements 43 are respectively and correspondingly disposed between the wedge prism 45 and the first prism 41 and between the wedge prism 45 and the second prism 42.

In other words, in this modified embodiment of the present invention, as shown in fig. 6, the at least one polarization beam splitting element 43 includes a first polarization beam splitting element 431 and a second polarization beam splitting element 432, and the wedge prism 45 is disposed between the first polarization splitting element 431 and the second polarization splitting element 432, such that there is an angular separation between the illumination optical path 100 of the illumination assembly 10 and the imaging optical path 300 of the imaging assembly 30, so that while ensuring that the projection end of the imaging assembly 30 (i.e. the position of the coupling-out face 601 of the coupling-out prism 60) is adjusted as desired, the arrangement angle of the illumination light path 100 of the illumination assembly 10 can be adjusted more flexibly, the structural layout of the whole miniature projection light engine 1 is more reasonable, and the whole miniature projection light engine 1 is more compact and small.

It should be noted that, due to the wedge prism 45 being introduced between the two polarization splitting elements 43, the first inclined plane 411 of the first prism 41 participating in the illumination optical path 100 and the second inclined plane 421 of the second prism 42 participating in the imaging optical path 300 are effectively separated, which facilitates to more flexibly adjust the specific arrangement position of the illumination optical path 100 and the orientation of the imaging optical path 300, and reduces the assembly difficulty of the micro projection light engine 1.

Exemplarily, as shown in fig. 6, the first polarization splitting element 431 is disposed between the first inclined surface 411 of the first prism 41 and the wedge prism 45, and the second polarization splitting element 432 is disposed between the second inclined surface 421 of the second prism 42 and the wedge prism 45. Thus, when the illumination assembly 10 provides S light along the illumination light path 100, the S light is firstly incident into the first prism 41 from the incident surface 401, and is then reflected by the first polarization beam splitter 431 to be emitted out of the first prism 41 from the turning surface 404; next, the S light passes through the light conversion element 441 for the first time, is reflected by the light reflection element 442 to pass through the light conversion element 441 again, and then is formed into P light, and finally the P light enters the first prism 41 from the folding surface 404; then, the P light sequentially passes through the first polarization beam splitter 431 and the second polarization beam splitter 432 to exit the second prism 42 from the display surface 402, and is modulated into S light by the LCoS chip 21 to enter the second prism 42 from the display surface 402; finally, the S light is reflected by the second polarization beam splitter 432 to exit from the exit surface 403, and is projected along the imaging optical path 300 of the imaging assembly 30 for imaging.

It is noted that in this variant embodiment of the present invention, where L represents the center distance between the display chip 20 and the coupling-out prism 60, and h represents the actually required offset distance of the coupling-out prism 60, the included angle θ between the imaging optical path 300 of the imaging assembly 30 and the display chip 20 satisfies the following relationship: tan theta is h/L; and the two base angles α and β of the second prism 42 satisfy the following relationships, respectively: α ═ β ═ 90 ° - θ)/2; the apex angle epsilon of the wedge prism 45 satisfies the following relationship: ε ═ η - α, where η is the base angle on the first prism 41 adjacent to the fold return face 404.

It should be noted that, in an example of the present invention, the first prism 41, the wedge-shaped prism 45, and the second prism 42 may be assembled by glue by way of full-surface gluing; the first polarization beam splitting element 431 may be, but is not limited to be, implemented as a conventional dielectric film stack to be plated on the first inclined surface 411 of the first prism 41 or one side surface of the wedge prism 45; similarly, the second polarization beam splitter 432 can also be, but is not limited to be, implemented as a conventional dielectric film stack to be plated on the second inclined plane 421 of the second prism 42 or the other side of the wedge prism 45. Of course, in other examples of the present invention, the first polarization beam splitting element 431 may also be implemented as a 3M-PBS film or WGF film to be directly glued between the first slope 411 of the first prism 41 and one side of the wedge prism 45; likewise, the second polarization splitting element 432 may also be implemented as a 3M-PBS film or WGF film to be directly glued between the second inclined surface 421 of the second prism 42 and the other side surface of the wedge prism 45.

In the above modified embodiment of the present invention, the refractive indexes of the first prism 41, the wedge prism 45, and the second prism 42 may be the same or different, and the description thereof is omitted.

It is worth mentioning that in some application scenarios, there may not be a problem of structural interference between the micro-projection light engine and the waveguide, but there is a problem of large size and volume of the micro-projection light engine due to the high position of the illumination assembly in the micro-projection light engine. Therefore, to address this issue, a micro projection light engine 1 according to another embodiment of the present invention is illustrated as shown in FIG. 7. In particular, this embodiment according to the invention differs from the above-described embodiment according to the invention in that: the special-shaped polarization beam splitting assembly 40 of the micro projection light engine 1 includes a first prism 41 for providing the incident surface 401, a second prism 42 for providing the exit surface 403, a wedge prism 45, and a first and a second polarization

beam splitting elements

431 and 432, and the wedge prism 45 is disposed between a first inclined surface 411 of the first prism 41 and a second inclined surface 421 of the second prism 42, respectively, wherein the first polarization beam splitting element 431 is disposed between the first inclined surface 411 of the first prism 41 and the wedge prism 45, and the second polarization beam splitting element 432 is disposed between the second inclined surface 421 of the second prism 42 and the wedge prism 45. In this way, a certain angular separation is generated between the illumination optical path 100 of the illumination assembly 10 and the imaging optical path 300 of the imaging assembly 30, so as to flexibly adjust the arrangement angle of the illumination optical path 100 of the illumination assembly 10, which helps to reduce the position height of the illumination assembly 10, so that the structural layout of the whole micro projection light engine 1 is more reasonable, and the whole micro projection light engine 1 is further more compact and small.

Preferably, in this embodiment of the present invention, the second prism 42 can be, but is not limited to, implemented as a prism with a right vertex angle (i.e. a right-angle prism), that is, the included angle γ between the exit surface 403 of the special-shaped polarization beam splitter component 40 and the display surface 402 is a right angle, so that the imaging optical path 300 of the imaging component 30 is parallel to the display chip 20, which helps to reduce the difficulty of assembling the micro projection light engine 1.

According to another aspect of the present invention, there is further provided a wearable display apparatus. As shown in fig. 1, the wearable display device includes a waveguide 50, an out-coupling prism 60 and any one of the above-mentioned micro projection light engines 1, wherein the out-coupling prism 60 is disposed between the waveguide 50 and the micro projection light engine 1, wherein the micro projection light engine 1 is configured to project polarized image light carrying image information, and wherein the out-coupling prism 60 is configured to couple the polarized image light from the micro projection light engine 1 into the waveguide 50, so as to project the polarized image light into human eyes through the waveguide 50 for displaying and imaging.

Preferably, the coupling-out surface 601 of the coupling-out prism 60 is parallel to the display surface 402 of the special-shaped polarization splitting assembly 40, so that when the display chip 20 is horizontally arranged, the coupling-out surface 601 of the coupling-out prism 60 is also kept in a horizontal direction, which helps to configure the waveguide 50 on the coupling-out surface 601 of the coupling-out prism 60, so as to avoid increasing the difficulty of designing optical paths and structures.

It should be noted that the micro-projection light engine 1 and the human eye may be located on the same side of the waveguide 50, or may be located on opposite sides of the waveguide 50 (i.e. different sides of the waveguide 50), which is not limited by the present invention, and only needs to ensure that the polarized image light from the micro-projection light engine 1 is projected into the human eye through the waveguide 50. Further, it will be understood by those skilled in the art that the type of the wearable display device is not limited, for example, the wearable display device may be a near-eye display device such as AR glasses, VR glasses, or the like.

According to another aspect of the present invention, as shown in fig. 8A, the present invention further provides a projection method of a micro projection light engine, which may include the following steps:

s100: emitting polarized illumination light with a first polarization state to an incident surface 401 of a special-shaped polarization beam splitter 40 along an illumination light path 100;

s200: transmitting the polarized illumination light with the first polarization state incident from the incident surface 401 to a display surface 402 of the special-shaped polarization beam splitter 40, and converting the polarized illumination light with the first polarization state into polarized illumination light with the second polarization state;

s300: modulating the polarized illumination light having the second polarization state emitted from the display surface 402 into polarized image light having the first polarization state;

s400: the polarized image light with the first polarization state incident from the display surface 402 is reflected to an exit surface 403 of the special-shaped polarization beam splitter assembly 40 in a bending manner, wherein an included angle between the exit surface 403 and the display surface 402 is an acute angle or an obtuse angle; and

s500: the polarized image light with the first polarization state emitted from the exit surface 403 is projected along an imaging optical path 300 to form an image.

It is noted that, as shown in fig. 8B, in the projection method of the micro-projection light engine of the present invention, the step S200 may include the steps of:

s210: the polarized illumination light with the first polarization state incident from the incident surface 401 is reflected to a folding surface 404 of the special-shaped polarization beam splitter assembly 40 in a folding manner;

s220: reflecting the polarized illumination light with the first polarization state emitted from the folding surface 404 in a folding manner, so that the polarized illumination light with the first polarization state is converted into polarized illumination light with a second polarization state after passing through a light conversion element 442 twice; and

s230: the polarized illumination light with the second polarization state incident from the folding surface 404 is transmitted to the display surface 402 of the special-shaped polarization beam splitter module 40.

It will be appreciated by persons skilled in the art that the embodiments of the invention described above and shown in the drawings are given by way of example only and are not limiting of the invention. The objects of the invention have been fully and effectively accomplished. The functional and structural principles of the present invention have been shown and described in the examples, and any variations or modifications of the embodiments of the present invention may be made without departing from the principles.

Claims

1. A miniature projection light engine, comprising:

2. The micro projection light engine of claim 1, wherein the shaped polarization beam splitter assembly comprises a first prism, a second prism, and at least one polarization beam splitter element, wherein a first inclined plane of the first prism and a second inclined plane of the second prism are oppositely disposed, and the at least one polarization beam splitter element is disposed between the first inclined plane of the first prism and the second inclined plane of the second prism, wherein a first side surface of the first prism serves as the incident surface of the shaped polarization beam splitter assembly, and two second side surfaces of the second prism serve as the exit surface and the display surface of the shaped polarization beam splitter assembly, respectively.

3. The micro projection light engine of claim 2, wherein the second prism is a prism having a vertex angle that is acute or obtuse.

4. The micro projection light engine of claim 3, wherein the first prism is a prism with an acute or obtuse vertex angle, and the exit surface of the shaped polarization beam splitting assembly is parallel to the entrance surface of the shaped polarization beam splitting assembly.

5. The micro-projection light engine of claim 2, wherein the special-shaped polarization beam splitter further comprises a polarization folding back component, and the special-shaped polarization beam splitter further has a folding back surface corresponding to the polarization folding back component, wherein the polarization folding back component is configured to reflect the polarized light with the first polarization state input from the folding back surface and convert the polarized light with the first polarization state into the polarized light with the second polarization state incident from the folding back surface.

6. The micro projection light engine of claim 5, wherein the other first side surface of the first prism serves as the folded surface of the shaped polarization beam splitter assembly, and the folded surface of the shaped polarization beam splitter assembly is parallel to the display surface of the shaped polarization beam splitter assembly.

7. The micro projection light engine of claim 1, wherein the shaped polarization beam splitter assembly comprises a first prism, a second prism, and at least one polarization beam splitter element, wherein a first inclined plane of the first prism and a second inclined plane of the second prism are oppositely disposed, and the at least one polarization beam splitter element is disposed between the first inclined plane of the first prism and the second inclined plane of the second prism, wherein two first side surfaces of the first prism serve as the incident surface and the display surface of the shaped polarization beam splitter assembly, and a second side surface of the second prism respectively serves as the exit surface of the shaped polarization beam splitter assembly.

8. The micro projection light engine of any one of claims 2 to 7, wherein the profiled polarizing beam splitting assembly further comprises a wedge prism and the wedge prism is disposed between the first inclined surface of the first prism and the second inclined surface of the second prism, respectively, wherein the at least one polarizing beam splitting element comprises a first polarizing beam splitting element and a second polarizing beam splitting element, wherein the first polarizing beam splitting element is disposed between the first inclined surface of the first prism and the wedge prism and the second polarizing beam splitting element is disposed between the second inclined surface of the second prism and the wedge prism.

9. The micro projection light engine of any of claims 2 to 7 wherein the polarizing beam splitting element is a dielectric film stack, a PBS film, or an WGF wire grid film.

10. The micro projection light engine of any one of claims 1 to 7, wherein the illumination assembly comprises an illumination source, a collimated color combination assembly and a polarization device, wherein the illumination source is configured to emit multiple monochromatic illumination lights, wherein the collimated color combination assembly is disposed between the illumination source and the polarization device, and is configured to collimates the multiple monochromatic illumination lights from the illumination source into a combined color illumination light propagating along the illumination light path, and wherein the polarization device is configured to convert the combined color illumination light into the polarized illumination light having the same polarization state.

11. The micro projection light engine of claim 10, wherein the illumination source is a RGB three-in-one light source, a light source consisting of an RB two-in-one light source and a G light source, or an L-shaped LED light source.

12. The micro projection light engine of claim 10, wherein the illumination assembly further comprises a light unifying device, wherein the light unifying device is disposed between the collimated color combining assembly and the polarizing device for unifying the color combined illumination light from the collimated color combining assembly.

13. The micro projection light engine of any of claims 1 to 7, wherein the display chip is an LCoS chip.

14. A miniature projection light engine, comprising:

15. The micro projection light engine of claim 14, wherein the second prism is a prism having a vertex angle of a right angle.

16. A wearable display device, comprising:

a waveguide; and

17. The wearable display device of claim 16, wherein an outcoupling surface of the outcoupling prism is parallel to the display surface of the profiled polarizing beam splitting assembly.

18. A wearable display device, comprising:

a waveguide; and

19. A method of projecting a miniature projection light engine, comprising the steps of:

20. The projection method of a micro projection light engine of claim 19, wherein the step of transmitting the polarized illumination light with the first polarization state incident from the incident surface to a display surface of the special-shaped polarization beam splitter assembly and converting the polarized illumination light with the first polarization state into polarized illumination light with the second polarization state comprises the steps of: