Miniature biprism projection system for reflecting illumination light source and near-to-eye display equipment

Abstract

The invention relates to the technical field of near-to-eye display, in particular to a miniature biprism projection system for a reflection illumination light source and near-to-eye display equipment. The miniature biprism projection system comprises an illumination light source, an image source, a first prism and a second prism, wherein the second prism is arranged between the first prism and the image source; the second prism is used for receiving the illumination light rays output by the illumination light source, reflecting the illumination light rays twice and then emitting the illumination light rays to the image source; the image source reflects the illumination light to form image light, and the image light is refracted by the second prism, then enters the first prism, is reflected twice in the first prism, and then is emitted to the exit pupil position. According to the projection system, the illumination light path and the imaging light path share the second prism, the illumination light is reflected twice by the second prism to the image source, the image light is refracted by the second prism, reflected twice by the first prism and then emitted to the exit pupil position, light path folding is achieved, and the size of the projection system is greatly reduced.

Description

Technical Field

[0001] The present invention relates to the field of near-eye display technology, and in particular to a micro dual-prism projection system and a near-eye display device for reflecting an illumination light source. Background Art

[0002] Since the concepts of virtual reality (VR) and augmented reality (AR) were proposed, the market for near-eye display devices based on VR or AR modes has made great progress. Among the many hardware implementations of AR or VR technology, near-eye display (NED) is the most effective implementation method that can bring the best experience to users. Because the near-eye display needs to be worn on the human head, its light weight and good display effect are particularly important.

[0003] The waveguide system is a representative of the thin and light solutions in the current near-eye display solutions. The thickness of the waveguide is relatively thin, generally within 3mm. The waveguide needs to be used in conjunction with a projection system. However, the existing projection systems are usually large in size, and the size of the projection system directly restricts the overall size of the display module. Summary of the invention

[0004] In view of this, embodiments of the present invention provide a micro dual-prism projection system and a near-eye display device for reflecting an illumination light source, so as to solve the technical problem of a large projection system volume in the prior art.

[0005] The technical solution provided by the embodiment of the present invention is as follows:

[0006] In a first aspect, the present invention provides a micro dual-prism projection system for reflecting an illumination light source, the system comprising: an illumination light source, an image source, a first prism and a second prism; the second prism is arranged between the first prism and the image source, the illumination light path and the imaging light path share the second prism, the second prism comprises: a first incident surface, a second incident surface, a first reflection surface and a first splitting surface, the four optical surfaces of the first incident surface, the second incident surface, the first reflection surface and the first splitting surface are respectively inclined and intersected to form an irregular quadrangular prism; the first incident surface of the second prism is used to receive the illumination light output by the illumination light source, the illumination light is reflected by the first reflection surface and the first splitting surface in sequence, and then is emitted to the image source through the second incident surface; the image source forms image light after reflecting the illumination light, the image light is transmitted through the second incident surface and the first splitting surface of the second prism, emitted to the first prism, and after being reflected twice in the first prism, emitted to the exit pupil position.

[0007] In an optional implementation, the first incident surface, the second incident surface, the first reflecting surface and the first light splitting surface are connected in sequence.

[0008] In an optional embodiment, the first prism includes: a second beam splitting surface, a second reflecting surface and an exit surface; the second beam splitting surface is arranged close to the first beam splitting surface, and the exit surface is arranged close to the exit pupil position, the image light enters the first prism through the second beam splitting surface, the second reflecting surface is used to reflect the light entering the first prism to the second beam splitting surface, and the second beam splitting surface is used to guide the light reflected by the second reflecting surface to the exit surface.

[0009] In an optional embodiment, the central rotation angles of the second incident surface and the second reflecting surface are consistent, the exit surface and the second incident surface are symmetrical about the second beam splitting plane, the first reflecting surface and the second reflecting surface are symmetrical about the second beam splitting plane, and the angle between the second beam splitting plane and the aperture set at the exit pupil position satisfies a preset angle.

[0010] In an optional implementation, a polarization splitting film and a quarter wave plate film are arranged between the first splitting surface and the second splitting surface, the polarization splitting film is arranged close to the first splitting surface, and the quarter wave plate film is arranged close to the second splitting surface.

[0011] In an optional implementation, the first incident surface, the second incident surface, and the exit surface are spherical surfaces, and the first reflection surface is a free-form surface.

[0012] In an optional embodiment, the system further includes: a front lens disposed between the second prism and the image source, wherein the front lens includes a single lens, a positive-negative cemented lens, or a lens group.

[0013] In an optional embodiment, the system further includes: a collimating element and a light homogenizing element, which are arranged between the illumination light source and the second prism.

[0014] In an optional implementation, the image source is a non-self-luminous display screen.

[0015] In a second aspect, the present invention provides a near-eye display device, comprising a waveguide system and a micro-dual-prism projection system for reflecting an illumination light source as described in the first aspect of the present invention and any embodiment of the first aspect, wherein the coupling end of the waveguide system is arranged at an exit pupil position of the micro-dual-prism projection system.

[0016] The technical solution of the present invention has the following advantages:

[0017] In the embodiment of the present invention, a micro dual-prism projection system and a near-eye display device for reflecting an illumination light source are provided. The illumination light emitted by the illumination light source is reflected twice by the second prism and then emitted to the image source. The illumination light is reflected by the image source to form an image light. The image source passes through the second prism and is reflected twice in the first prism, and then emitted from the exit pupil position. The micro dual-prism projection system, by reasonably setting the optical surfaces of the second prism and the first prism, enables the illumination light path and the imaging light path to share the second prism, and realizes the folding of the light path inside the prism, which greatly reduces the volume of the projection system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 is a three-dimensional cross-sectional view of a micro dual-prism projection system for reflecting an illumination light source in an embodiment of the present invention;

[0020] Figure 2 Schematic diagram of the three-dimensional structure of a micro dual-prism projection system for reflecting an illumination light source in an embodiment of the present invention;

[0021] Figure 3 A polarized light path diagram of a micro dual-prism projection system for reflecting an illumination light source in an embodiment of the present invention;

[0022] Figure 4 Schematic diagram of an imaging light path of a micro dual-prism projection system for reflecting an illumination light source in an embodiment of the present invention;

[0023] 5(a) and 5(b) are image quality evaluation diagrams of a micro dual-prism projection system for reflecting an illumination light source in an embodiment of the present invention;

[0024] Figure 6 A three-dimensional diagram of a near-eye display device in an embodiment of the present invention. DETAILED DESCRIPTION

[0025] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and "third" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance.

[0027] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can also be the internal connection of two components, it can be a wireless connection, or it can be a wired connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0028] In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0029] Example 1

[0030] The embodiment of the present invention provides a micro dual prism projection system for reflecting an illumination light source, such as Figures 1 to 3 As shown, the system includes: an illumination light source, an image source, a first prism 102 and a second prism 103, wherein the second prism 103 is arranged between the first prism 102 and the image source; the second prism 103 is shared by the illumination light path and the imaging light path. The second prism 103 includes: a first incident surface S1, a second incident surface S4, a first reflection surface S2 and a first beam splitting surface S31; the first incident surface S1 of the second prism 103 is used to receive the illumination light output by the illumination light source, and the illumination light is reflected by the first reflection surface S2 and the first beam splitting surface S31 in sequence, and then emitted to the image source through the second incident surface S4; the image source reflects the illumination light to form an image light, and the image light is transmitted through the second incident surface S4 and the first beam splitting surface S31 of the second prism 103, emitted to the first prism 102, and after being reflected twice in the first prism 102, emitted to the exit pupil position. A stop 101 can be arranged at the exit pupil position to accurately define the exit pupil size of the projection system.

[0031] Specifically, the illumination light source may be a device such as an LED lamp 109, and the image source is used for image display, for example, a micro display 106 may be used. When the system is working, the light emitted by the illumination light source passes through the second prism 103 and then shines on the image source, providing illumination light for the non-self-luminous image on the image source, and the illumination light is reflected by the image source to form image light, and the image light passes through the second prism 103 and the first prism 102 and then outputs from the exit pupil position. That is, the micro dual-prism projection system provided in this embodiment realizes the function of projecting the non-self-luminous image of the image source onto the projection surface.

[0032] In an optional embodiment, the first incident surface S1, the second incident surface S4, the first reflection surface S2 and the first splitting surface S31 of the second prism 103 are connected in sequence, and by reasonably setting the positions and surface shapes of the first incident surface S1, the second incident surface S4, the first reflection surface S2 and the first splitting surface S31, the transmission light path of the illumination light in the second prism 103 is cross-folded, thereby reducing the volume of the second prism 103. Specifically, the first beam splitting surface S31 is located between the first reflecting surface S2 and the first incident surface S1, the second incident surface S4 is located between the first reflecting surface S2 and the first incident surface S1, and the four optical surfaces are tilted and intersected to form an irregular quadrangular prism; and the positions of the four optical surfaces satisfy: the illumination light passing through the first incident surface S1 and emitted toward the first reflecting surface S2 is reflected by the first reflecting surface S2 and then emitted toward the first beam splitting surface S31 and reflected by the first beam splitting surface S31, and the illumination light reflected by the first beam splitting surface S31 passes between the first incident surface S1 and the first reflecting surface S2 and is emitted toward the second incident surface S4, thereby realizing the folding of the illumination light path within the second prism 103.

[0033] The present embodiment provides a micro dual-prism projection system for reflecting an illumination light source. The illumination light emitted by the illumination light source is reflected twice by the second prism and then emitted toward the image source. The illumination light is reflected by the image source to form image light. The image light passes through the second prism and is reflected twice in the first prism. Then, the image light is emitted from the exit pupil position, thereby realizing light path folding and greatly reducing the volume of the projection system.

[0034] In an optional embodiment, if Figure 3As shown, the first prism 102 includes: a second beam splitting surface S32, a second reflection surface S5 and an exit surface S6 which are arranged in sequence. The second beam splitting surface S32 is arranged close to the first beam splitting surface S31, and the second beam splitting surface S32 and the first beam splitting surface S31 have the same surface shape, preferably a plane; the exit surface S6 is arranged close to the exit pupil position. The illumination light enters the first prism 102 through the second beam splitting surface S32, and the second reflection surface S5 is used to reflect the light entering the first prism to the second beam splitting surface S32. The second beam splitting surface S32 is used to guide the light reflected by the second reflection surface S5 to the exit surface S6. Specifically, the illumination light output by the illumination light source is irradiated on the image source after passing through the second prism, and is reflected by the image source to form image light. The image light is transmitted through the second prism and the second beam splitting surface S32 of the first prism to enter the first prism. The image light entering the first prism is reflected by the second reflecting surface to the second beam splitting surface S32, and then reflected by the second beam splitting surface S32, and then emitted from the exit pupil position through the exit surface.

[0035] In an optional embodiment, in order to meet the compact design of the first prism and the second prism and the optical path folding of the illumination light and the image light, the central rotation angles of the second incident surface S4 and the second reflection surface S5 are consistent, the exit surface S6 and the second incident surface S4 are symmetrical about the second beam splitter surface S32, the first reflection surface S2 and the second reflection surface S5 are symmetrical about the second beam splitter surface S32, and the angle between the second beam splitter surface S32 and the aperture 101 set at the exit pupil position meets the preset angle. Among them, the consistency of the central rotation angle means that the rotation angles of the second incident surface and the second reflection surface relative to the projection system coordinate system are consistent, that is, the central principal planes of the second incident surface and the second reflection surface are parallel to each other. At the same time, the exit surface and the second incident surface are symmetrical about the second beam splitter surface S32, and the first reflection surface and the second reflection surface are symmetrical about the second beam splitter surface S32, which can be approximately symmetrical in actual settings. In addition, the angle between the second beam splitter surface S32 and the aperture can be between 50° and 60°, so that the first prism and the second prism can constitute a five-surface dual prism system. In practical applications, the included angle between the second light splitting surface S32 and the aperture may be 55°.

[0036] It should be noted that the second beam-splitting surface S32 of the first prism 102 and the first beam-splitting surface S31 of the second prism 103 are adjacent surfaces of the two prisms. Since the two have the same surface shape and are arranged in a close fit, it can be understood that the second beam-splitting surface S32 of the first prism 102 and the first beam-splitting surface S31 of the second prism approximately coincide with each other. Therefore, the exit surface S6 and the second incident surface S4 are also symmetrical about the first beam-splitting surface S31, the first reflecting surface S2 and the second reflecting surface S5 are also symmetrical about the first beam-splitting surface S31, and the angle between the first beam-splitting surface S31 and the aperture 101 set at the exit pupil position also satisfies the above-mentioned preset angle.

[0037] By arranging the surfaces of the first prism and the second prism in this manner, the entire system can be quickly constructed.

[0038] In an optional embodiment, a polarizing beam splitter (PBS) film and a quarter-wave plate (QWP) film are arranged between the first beam splitter surface S31 and the second beam splitter surface S32, wherein the polarizing beam splitter film is arranged close to the first beam splitter surface S31, and the quarter-wave plate film is arranged close to the second beam splitter surface S32. Among them, the QWP film can change the polarization state of light, and the PBS film can realize the reflection of the first polarized light and the transmission of the second polarized light. The first polarized light can be P polarized light or S polarized light. The following description takes the example that the PBS film can realize the reflection of S polarized light and the transmission of P polarized light.

[0039] Specifically, Figure 3As shown in FIG. 1 , when the illumination light (the light is S polarized light) of the illumination light source enters the second prism 103 and is reflected by the first reflection surface S2 to the first beam splitting surface S31, the PBS film can realize the reflection of the light, and the reflected light is irradiated on the image source through the second incident surface S4. The image source adopts the liquid crystal on silicon display technology (Liquid Crystal On Silicon (LCOS) and other non-self-luminous display screens, when light is irradiated on an image source, the image source changes the polarization direction of the linearly polarized light while reflecting the light. As a result, after reflection from the image source, the S-polarized light is converted into P-polarized light and enters the second prism 103 again. At this time, the P-polarized light can pass through the PBS film on one side of the first beam splitting surface S31, and then realizes a change in polarization state when passing through the QWP film, that is, it is converted from P-polarized light to right-handed circularly polarized light or left-handed circularly polarized light (the direction of left-handed or right-handed rotation is related to the angle of QWP fitting) and enters the first prism 102. The circularly polarized light entering the first prism is reflected by the second reflecting surface S5 and the direction of rotation is changed again. The reflected circularly polarized light is irradiated to the second beam splitting surface S32 and then passes through the QWP film, and the polarization state is changed to S-polarized light. The S-polarized light is reflected by the PBS film to the exit surface S6 and is emitted from the exit pupil position.

[0040] In an optional embodiment, the first incident surface S1, the second incident surface S4, the second reflective surface S5 and the exit surface S6 are spherical surfaces, the first splitting surface S31 and the second splitting surface S32 are planes, and the first reflective surface S2 is a free-form reflective surface. Specifically, except for the splitting surface, the first reflective surface and the second reflective surface of the film, all other surfaces can be transmissive surfaces, and their surface shape can be spherical.

[0041] In an optional embodiment, if Figures 1 to 3 As shown, the system further includes: a front lens, which is arranged between the second prism 103 and the image source, and the illumination light path and the imaging light path share the second prism 103 and the front lens. The front lens includes a single lens, a positive-negative cemented lens or a lens group. Figure 1 In the illustrated embodiment, the front lens includes a positive-negative cemented lens composed of a first lens 104 and a second lens 105. The first lens 104 and the second lens 105 are made of glass with different refractive indices and are cemented to eliminate chromatic aberration.

[0042] The system further comprises: a collimating element and a light homogenizing element, which are arranged between the illumination light source and the second prism. The collimating element may be a total internal reflection lens 108 , and the light homogenizing element may be a compound eye array 107 .

[0043] Specifically, a total internal reflection lens 108 and a fly-eye array 107 are arranged between the illumination light source and the first incident surface S1 of the second prism 103, wherein the total internal reflection lens is used to collimate the light beam output by the illumination light source, and the fly-eye array is used to achieve uniform illumination of the light beam. At the same time, in order to make the light input to the second prism 103 S-polarized light, the illumination light source can be a polarized light source, and a polarizing element can also be arranged between the illumination light source and the second prism, so that the light beam output by the illumination light source becomes S-polarized light.

[0044] Example 2

[0045] This embodiment provides a micro dual prism projection system for reflecting an illumination light source, such as Figures 1 to 3 As shown, the system includes a micro display 106, an LED lamp 109, an aperture 101, a first prism 102, a second prism 103, a first lens 104 of a double-cemented lens group, a second lens 105 of a double-cemented lens group, a compound eye array 107, and a total internal reflection lens 108. The second prism includes a first incident surface S1, a second incident surface S4, a first reflection surface S2, and a first light splitting surface S31 connected in sequence; the first prism includes a second light splitting surface S32, a second reflection surface S5, and an exit surface S6 arranged in sequence. The micro display 106 is a non-self-luminous display screen such as a liquid crystal on silicon (LCOS) display technology. The projection system includes an illumination optical path and an imaging optical path. The illumination optical path includes an LED lamp 109 , a compound eye array 107 , a total internal reflection lens 108 , a second prism 103 and a double-cemented lens group, and the imaging optical path includes a micro display 106 , a double-cemented lens group, a second prism 103 and a first prism 102 .

[0046] In practical applications, the projection system works according to the following process:

[0047] The LED lamp 109 emits an illumination light, which is collimated by the total internal reflection lens 108 and homogenized by the compound eye array 107, and enters the second prism 103 through the first incident surface S1, wherein the light entering the second prism 103 is S polarized light, and the polarizing element can be located at the first incident surface S1 or at any position before reaching the first incident surface S1. In the present embodiment, the polarizing element is located on the light exiting surface of the total internal reflection lens 108; after entering the second prism, the illumination light is reflected by the first reflection surface S2 and incident on the first splitting surface S31; wherein a PBS film and a QWP film are arranged between the first splitting surface S31 and the second splitting surface S32, the PBS film is attached to the second prism side, and the QWP film is attached to the first prism side, and the function of the PBS film is to realize S polarized light reflection and P polarized light transmission, therefore, the illumination light will be reflected at the first splitting surface S31, and then emitted through the second incident surface S4, pass through the double cemented lens group, and be emitted to the micro display 106. After the illumination light is reflected by the micro display 106, it forms an image light. The image light passes through the double-cemented lens group again and enters the second prism from the second incident surface S4. For the LCOS display screen, the pixel screen with imaging information can rotate the polarization state of the incident light by 90°. At this time, the polarization state of the light is P polarized light. When it is incident on the first splitting surface S31 again, according to the functional characteristics of PBS, the image light passes through the PBS film, and the image light passes through the QWP to become right-handed circularly polarized light or left-handed circularly polarized light. The left-handed or right-handed rotation direction is related to the angle of QWP fitting. After the circularly polarized light is reflected by the second reflecting surface S5, the rotation direction is changed to left-handed circularly polarized light or right-handed polarized light, which is opposite to the rotation direction of the polarization state before reflection. When the opposite polarization state is incident on the QWP of the splitting surface again, the polarization state will become S polarized light. At this time, according to the functional characteristics of PBS, the image light will be reflected, and after emitting from the exit surface S6 of the first prism, it will be emitted from the exit pupil position.

[0048] Specifically, when the projection system works according to the above workflow, for the illumination light path, after the light is reflected by the first reflection surface S2 and then reflected by the first splitting surface S31 again, since the PBS film is set on the surface of the first splitting surface S31, there are certain requirements for the incident angle of the light. By optimizing the surface shape of the first reflection surface S2, the incident angle of the light on the PBS film can be controlled. In this embodiment, the incident angle range of the central main light of each field of view on the PBS film is 30-35°. This angle range is small. At this time, the illumination light has a higher reflection efficiency, which can improve the light effect and brightness uniformity. Among them, each field of view in the central main light of each field of view represents a different angle of light emission. Since the system has a certain pupil size, the light emitted at each angle is not a simple line but a cylinder. The central main light refers to the center position of this cylinder.

[0049] like Figure 4The figure shows the design diagram of the imaging optical path. In this embodiment, the imaging optical path adopts a coaxial system. The design idea is a reverse design, that is, it is assumed in the design process that the light is emitted from the exit pupil position and incident on the micro display 106 in the reverse direction along the imaging optical path, which is helpful for image quality analysis within the field of view. In the imaging optical path design, the optically effective surfaces are the second beam splitting surface S32, the second reflection surface S5 and the exit surface S6 of the first prism 102, the second incident surface S4 and the first beam splitting surface S31 of the second prism 103, and the first surface S7, the second surface S8 and the third surface S9 of the two lenses in the positive-negative double glued lens group. According to the imaging optical path, the incident angle of the main light of the micro display 106 can be effectively controlled. At this time, the incident angle of the field light at the center of each field of view on the micro display 106 is less than 0.5°, and the brightness uniformity is good. The relevant parameters of the optically effective surface are shown in Table 1 below:

[0050] Table 1 Parameters of optical surfaces in the imaging optical path

[0051]

[0052] Since the illumination optical path generally does not have imaging quality design requirements, in addition to the parameter data in Table 1 above, for the first incident surface S1 and the first reflection surface S2, the first incident surface S1 is a spherical surface with a curvature radius of 25.676, and the first reflection surface S2 is a free-form surface reflection surface, where the free-form surface parameters satisfy the following equations.

[0053]

[0054] Where c is the inverse of the radius of curvature, r is the radial distance of a point on the surface, k is the quadratic constant, and C j are the polynomial coefficients.

[0055] The Y radius of the first reflection surface S2 is 19.4119, k is 0, C j The polynomial coefficients are shown in Table 2 below:

[0056] Table 2 Coefficients of the free surface expression of the first reflecting surface S2

[0057]

[0058]

[0059] Based on the projection system structure and related parameters, the overall optical parameters of the projection system are shown in Table 3 below:

[0060] Table 3 System parameters of the projection system

[0061] parameter Numeric Remark Field of view 40° Diagonal field of view focal length 9.07mm Exit pupil diameter 3.6mm Exit pupil distance 0.3mm 3D volume parameters 16mm*11mm*7mm

[0062] In addition, the image quality of the imaging optical path in the projection system can also be evaluated. Figures 5(a) and 5(b) are image quality evaluation diagrams of the imaging optical path, where Figure 5(a) is an MTF (Modulation Transfer Function) diagram, the horizontal axis is the spatial frequency, the unit is line pair / mm (lp / mm), and the vertical axis is the modulation transfer function. It can be seen from Figure 5(a) that at 120lp / mm, the full field MTF>0.4, and the imaging quality is good; Figure 5(b) is a distortion diagram, the horizontal axis is the horizontal FOV (field of view), and the vertical axis is the vertical FOV. It can be seen from Figure 5(b) that the overall optical distortion is less than 3%.

[0063] Example 3

[0064] This embodiment also provides a near-eye display device, which includes a waveguide system and the micro-dual prism projection system for reflecting the illumination light source described in the above embodiment, wherein the coupling end of the waveguide system is arranged at the exit pupil position of the micro-dual prism projection system, and a stop 101 is arranged at the coupling end. Figure 6 The figure shows a 3D image of a near-eye display device, in which 201 is a micro dual-prism projection system and 202 is a waveguide system. The waveguide system in this embodiment can be a waveguide element with a pupil expansion function, such as an array waveguide, a holographic waveguide or an embossed grating waveguide.

[0065] The present invention provides a micro-projection system and a near-eye display device, wherein the imaging light path and the illumination light path share a second prism (and a front lens), the first prism and the second prism share a surface with a light splitting function, and the overall system uses two reflecting surfaces and two light splitting surfaces to fold the light path, thereby greatly reducing the volume of the projection system.

[0066] Although the exemplary embodiments and their advantages have been described in detail, those skilled in the art may make various changes, substitutions and modifications to these embodiments without departing from the spirit of the present invention and the scope of protection defined by the appended claims, and such modifications and variations all fall within the scope defined by the appended claims. For other examples, those of ordinary skill in the art should readily understand that the order of the process steps may be changed while maintaining the scope of protection of the present invention.

[0067] In addition, the scope of application of the present invention is not limited to the processes, mechanisms, manufactures, material compositions, means, methods and steps of the specific embodiments described in the specification. From the disclosure of the present invention, it will be easily understood by those skilled in the art that the processes, mechanisms, manufactures, material compositions, means, methods or steps that currently exist or will be developed in the future, which perform substantially the same functions as the corresponding embodiments described in the present invention or obtain substantially the same results, can be applied according to the present invention. Therefore, the claims attached to the present invention are intended to include these processes, mechanisms, manufactures, material compositions, means, methods or steps within their scope of protection.

Claims

1. A micro dual prism projection system for reflecting an illumination light source, characterized in that: The system comprises: an illumination light source, an image source, a first prism and a second prism; The second prism is arranged between the first prism and the image source, and the illumination light path and the imaging light path share the second prism, and the second prism comprises: a first incident surface, a second incident surface, a first reflection surface and a first light splitting surface, and the four optical surfaces of the first incident surface, the second incident surface, the first reflection surface and the first light splitting surface are respectively inclined and intersected to form an irregular quadrangular prism; The first incident surface of the second prism is used to receive the illumination light output by the illumination light source, and the illumination light is reflected by the first reflection surface and the first light splitting surface in sequence, and then emitted to the image source through the second incident surface; The image source reflects the illumination light to form image light, and the image light is transmitted through the second incident surface and the first beam splitting surface of the second prism, directed toward the first prism, and after being reflected twice in the first prism, directed toward the exit pupil position.

2. The micro dual prism projection system for reflecting an illumination light source according to claim 1, characterized in that: The first incident surface, the second incident surface, the first reflecting surface and the first light splitting surface are connected in sequence.

3. The micro dual prism projection system for reflecting an illumination light source according to claim 2, characterized in that: The first prism includes: a second light splitting surface, a second reflecting surface and an emitting surface; The second beam splitting surface is arranged close to the first beam splitting surface, and the exit surface is arranged close to the exit pupil position. The image light enters the first prism through the second beam splitting surface, and the second reflection surface is used to reflect the light entering the first prism to the second beam splitting surface. The second beam splitting surface is used to guide the light reflected by the second reflection surface to the exit surface.

4. The micro dual-prism projection system for reflecting an illumination light source according to claim 3, characterized in that: The central rotation angles of the second incident surface and the second reflecting surface are consistent, the exit surface and the second incident surface are symmetrical about the second splitting plane, the first reflecting surface and the second reflecting surface are symmetrical about the second splitting plane, and the angle between the second splitting plane and the aperture set at the exit pupil position satisfies a preset angle.

5. The micro dual-prism projection system for reflecting an illumination light source according to claim 3, characterized in that: A polarization beam splitting film and a quarter wave plate film are arranged between the first beam splitting surface and the second beam splitting surface. The polarization beam splitting film is arranged close to the first beam splitting surface, and the quarter wave plate film is arranged close to the second beam splitting surface.

6. The micro dual-prism projection system for reflecting an illumination light source according to claim 3, characterized in that: The first incident surface, the second incident surface and the exit surface are spherical surfaces, and the first reflection surface is a free-form surface.

7. The micro dual-prism projection system for reflecting an illumination light source according to claim 1, characterized in that: The system further comprises: a front lens disposed between the second prism and the image source, wherein the front lens comprises a single lens, a positive-negative cemented lens or a lens group.

8. The micro dual-prism projection system for reflecting an illumination light source according to claim 1, characterized in that: The system further comprises: a collimating element and a light homogenizing element, which are arranged between the illumination light source and the second prism.

9. The micro dual-prism projection system for reflecting an illumination light source according to claim 1, characterized in that: The image source is a non-self-luminous display screen.

10. A near-eye display device, characterized in that: The device comprises a waveguide system and a micro dual-prism projection system for reflecting an illumination light source as claimed in any one of claims 1 to 9, wherein the coupling end of the waveguide system is arranged at an exit pupil position of the micro dual-prism projection system.

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