Projection display system and projection device

Abstract

The embodiment of the present application provides a projection display system and a projection device; wherein the projection display system comprises a first prism, a second prism and a reflecting element, the second prism is located between the first prism and the reflecting element, and at least one of the first prism and the second prism is a free-form prism; the first prism comprises a first surface close to an image source surface S1, a second surface close to a projection surface S2, and an incident surface connected with the first surface and the second surface, the incident surface is used for allowing illumination light to enter the first prism; the second prism comprises a third surface close to the second surface, a fourth surface close to the reflecting element, and a reflecting surface connected with the third surface and the fourth surface; a light splitting element and a phase retarder are arranged between the second surface and the third surface, and the reflecting element is opposite to the image source surface S1 in position. The projection display system of the embodiment of the present application can reduce the number of lenses in the system, and meanwhile can ensure the quality of the projection picture.

Description

Technical Field

[0001] This application relates to the field of optical display technology, and more specifically, to a projection display system and a projection device. Background Technology

[0002] Among various projection products, taking AR headsets as an example, the projection optics system is the key technology. The quality of the projected image and the overall thinness and lightness of the device are primary considerations. Existing AR (Augmented Reality) headsets mainly use LCOS (Liquid Crystal on Silicon) displays. However, because LCOS projection optics systems rely on passive illumination, the overall system size is large, hindering the miniaturization and thinness of the product design. Summary of the Invention

[0003] The purpose of this application is to provide a new technical solution for a projection display system and projection equipment.

[0004] In a first aspect, embodiments of this application provide a projection display system. The projection display system is used to project light rays projected onto an image source surface S1 onto a projection surface S2, characterized in that it includes: a first prism and a second prism, and a reflecting element, wherein the second prism is located between the first prism and the reflecting element, and at least one of the first prism and the second prism is a freeform prism;

[0005] The first prism includes a first surface near the image source surface S1, a second surface near the projection surface S2, and an incident surface connected to the first surface and the second surface. The incident surface is used to allow light to enter the first prism.

[0006] The second prism includes a third surface disposed close to the second surface, a fourth surface disposed close to the reflective element, and a reflective surface connected to the third surface and the fourth surface;

[0007] A beam splitter and a phase delayer are disposed between the second surface and the third surface, and the reflective element is positioned opposite the image source surface S1.

[0008] Optionally, the projection display system further includes an LCOS display chip, the location of which forms the image source surface S1.

[0009] Optionally, the first prism and the second prism include at least one freeform surface.

[0010] Optionally, the fourth surface of the second prism is a freeform surface.

[0011] Optionally, the first surface of the first prism is a freeform surface or an aspherical surface.

[0012] Optionally, the incident surface of the first prism and the reflecting surface of the second prism are aspherical or freeform surfaces.

[0013] Optionally, the first surface is a total internal reflection surface; the light rays are reflected twice during the process of being projected from the incident surface through the first prism to the image source surface S1, one of which is a total internal reflection and occurs on the first surface.

[0014] Optionally, the fourth surface is a total internal reflection surface; the light undergoes four reflections during its projection from the image source surface S1 to the projection surface S2, one of which is a total internal reflection and occurs on the fourth surface.

[0015] Optionally, the second face of the first prism and the third face of the second prism are glued together to form a glued prism.

[0016] Optionally, when the light projected onto the incident surface is natural light, a polarizer is provided on the incident surface to convert the natural light into linearly polarized light.

[0017] Optionally, the image source surface S1 reflects the first linearly polarized light emitted from the first surface to form a second linearly polarized light with a changed polarization direction.

[0018] After the second linearly polarized light passes through the beam splitter, it is directed towards the phase retarder. The phase retarder converts the second linearly polarized light into circularly polarized light, which then travels towards the reflective element. The reflective element reflects the circularly polarized light to the third surface. When the circularly polarized light passes through the phase retarder, it becomes the second linearly polarized light again, and is then reflected by the beam splitter back to the phase retarder. The phase retarder converts the second linearly polarized light into circularly polarized light, which then travels from the third surface to the fourth surface. After being totally internally reflected by the fourth surface, the circularly polarized light travels towards the reflective surface. The circularly polarized light is reflected by the reflective surface, penetrates the fourth surface, and travels towards the projection surface S2.

[0019] Secondly, embodiments of this application provide a projection device. The projection device includes:

[0020] shell;

[0021] The projection display system as described in the first aspect.

[0022] The beneficial effects of this application are as follows:

[0023] According to the projection optical system provided in the embodiments of this application, by using a combination of two prisms, at least one of which is a freeform prism, and with a new optical architecture, the number of lenses used in the entire projection optical system can be reduced while ensuring the quality of the projected image. Based on the relatively compact optical architecture and the small number of optical lenses used, the size of the entire projection optical system can be reduced, thereby facilitating the miniaturization and thinning design of projection products.

[0024] Other features and advantages of this specification will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0025] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of this specification and, together with their description, serve to explain the principles of this specification.

[0026] Figure 1 This is one of the structural schematic diagrams of the projection optical system provided in the embodiments of this application;

[0027] Figure 2 This is a second schematic diagram of the projection optical system provided in the embodiments of this application.

[0028] Explanation of reference numerals in the attached figures:

[0029] 1. First prism; 2. Second prism; 3. Reflective element; 4. LCOS display chip; 5. Beam splitter; 6. Phase delay unit; 7. Polarizer; 8. Light source;

[0030] 11. First surface; 12. Second surface; 13. Surface of incidence;

[0031] 21. Third side; 22. Fourth side; 23. Reflecting surface

[0032] 01. First linearly polarized light; 02. Second linearly polarized light; 03. Circularly polarized light;

[0033] S1, image source plane; S2, projection plane. Detailed Implementation

[0034] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present application.

[0035] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application and its application or use.

[0036] Technologies and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such technologies and equipment should be considered part of the specification.

[0037] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0038] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0039] The projection display system and projection device provided in the embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0040] According to one embodiment of this application, a projection display system is provided, which can be applied in a projection device to project light carrying image information into an image. The projection device may be, for example, an AR head-mounted display (HMD), an in-vehicle projection device, or a home micro-projection device; this application does not limit the specific form of the projection device.

[0041] According to the projection display system provided in the embodiments of this application, see [link to relevant documentation]. Figure 1 and Figure 2 The projection display system is configured to project light rays projected onto the image source surface S1 onto the projection surface S2.

[0042] The projection display system provided according to the above embodiments may include an illumination component and an imaging component. The illumination component is mainly used to provide, for example, illumination light to the image source surface S1, where the illumination light is linearly polarized light. The imaging component is mainly used to output projection light carrying image information from the image source surface S1 to the projection surface S2 to project and form a projected image. The projection light is linearly polarized light whose polarization direction is changed after reflection from the image source surface S1.

[0043] The projection display system provided in this application embodiment is described in [reference]. Figure 1 and Figure 2 It includes: a first prism 1 and a second prism 2, and a reflecting element 3, wherein the second prism 2 is located between the first prism 1 and the reflecting element 3, and at least one of the first prism 1 and the second prism 2 is a freeform prism.

[0044] The first prism 1 includes a first surface 11 near the image source surface S1, a second surface 12 near the projection surface S2, and an incident surface 13 connected to the first surface 11 and the second surface 12. The incident surface 13 is used to allow light to enter the first prism 1. The second prism 2 includes a third surface 21 near the second surface 12, a fourth surface 22 near the reflecting element 3, and a reflecting surface 23 connected to the third surface 21 and the fourth surface 22. A beam splitter 5 and a phase retarder 6 are disposed between the second surface 12 and the third surface 21, and the reflecting element 3 is positioned opposite the image source surface S1.

[0045] Among them, the light rays incident from the incident surface 13 are illumination rays, which can be linearly polarized light.

[0046] According to the projection display system provided in the above embodiments of this application, the imaging component and the illumination component share the first prism 1 and the second prism 2, and a beam splitter 5 and a phase delayer 6 are introduced between them, thereby realizing optical path folding, making the entire optical architecture more compact and reducing the size of the projection display system.

[0047] In the above embodiments of this application, one or both of the first prism 1 and the second prism 2 can be freeform prisms. In the optical architecture of a projection display system, the use of freeform prisms, compared to aspherical prisms, can reduce the number of lenses used in the entire projection display system, thereby helping to reduce the overall size and weight of the projection display system.

[0048] As a preferred embodiment of this application, both the first prism 1 in the illumination assembly and the second prism 2 in the imaging assembly can be freeform prisms. This significantly reduces the weight of the entire projection display system, achieving lightweight design while maintaining good projection image quality.

[0049] See Figure 1 and Figure 2 The projection display system provided in the above embodiments of this application uses a freeform prism, which eliminates the need to introduce many lenses inside the system. The overall optical architecture is very compact and simple, and it can also achieve good imaging quality.

[0050] The projection display system can be equipped with optical waveguide devices to transmit the projected light to the human eye, so that the user can see the projected image.

[0051] See Figure 2 , Figure 2 S2 shown in the diagram is the projection plane, which is also the pupil plane of the entire system.

[0052] The projection display system provided in this application has a simple and compact overall optical structure with few internal optical lenses. The entire optical architecture can consist of only two prisms, a reflective element 3, and an image source surface S1. A preferred embodiment is that both prisms are freeform prisms, one of which is a first prism 1, which can be used in the illumination assembly, and the other is a second prism 2, which can be used in the imaging assembly. The use of freeform prisms can reduce the number of optical components. The projected light rays ultimately pass through the projection surface S2 (i.e., the exit pupil surface) to produce a clear projected image at infinity.

[0053] According to the above embodiments of this application, a beam splitter 5 and a phase delayer 6 are introduced between the first prism 1 and the second prism 2.

[0054] The beam splitter 5 can transmit a portion of light while simultaneously reflecting a portion of light.

[0055] For example, the beam splitter 5 can transmit linearly polarized light in one polarization direction and reflect linearly polarized light in another polarization direction.

[0056] The phase delayer 6 can be used to convert between linearly polarized light and circularly polarized light, that is, to convert linearly polarized light into circularly polarized light, or to convert circularly polarized light into linearly polarized light.

[0057] According to the projection optical system provided in this application, by employing a combination of two prisms, with at least one of the prisms being a freeform prism, and combined with a new optical architecture, the number of lenses used in the entire projection optical system and the use of optical waveguide elements can be reduced, while ensuring the quality of the projected image. Based on the relatively compact optical architecture and the reduced number of lenses, the overall size of the projection optical system can be reduced, thereby facilitating the miniaturization and thinning of projection products.

[0058] See some examples in this application. Figure 1 and Figure 2 The projection display system also includes an LCOS display chip 4, and the position of the LCOS display chip 4 forms the image source surface S1.

[0059] According to the above example, the LCOS display chip 4 is an imaging component, which is designed to be located on one side of the first surface 11 of the first prism 1, with a certain air gap between it and the first surface 11.

[0060] The LCOS display chip 4 itself does not emit light. The illumination light emitted through the first prism 1 can be projected onto the LCOS display chip 4 (i.e., the image source surface S1), and the LCOS display chip 4 can make the illumination light carry image information, and the resulting projection light is directed toward the second prism 2.

[0061] It should be noted that the position of the image source surface S1 is not limited to the LCOS display chip 4 mentioned above, but can also be other non-light-emitting display chips, which are not limited in this application.

[0062] In some examples of this application, the first prism 1 and the second prism 2 include at least one freeform surface.

[0063] Specifically, in the projection display system, both the first prism 1 and the second prism 2 can be freeform prisms; wherein the first prism 1 can have one or more freeform surfaces, and the second prism 2 can also have one or more freeform surfaces, and the resulting projection display system has at least one freeform surface.

[0064] Optionally, when both the first prism 1 and the second prism 2 are freeform prisms, each can have at least two freeform surfaces. In this case, the resulting projection display system has at least four freeform surfaces. Having more freeform surfaces in the projection display system can further reduce the overall system size and weight while maintaining image quality.

[0065] It should be noted that, for the first prism 1 and the second prism 2, when both are freeform prisms, all faces of these two prisms can be freeform surfaces. However, considering that optical elements such as beam splitters 5 and phase retarder 6 may need to be placed on the two adjacent faces of these two prisms, it would be difficult to manufacture these optical elements on freeform surfaces, leading to manufacturing difficulties, low yield, and high costs. Therefore, the two adjacent faces of these two prisms can be designed as aspherical surfaces, for example, instead of freeform surfaces.

[0066] In some examples of this application, the fourth surface 22 of the second prism 2 is a freeform surface.

[0067] According to the above example, by designing the surface shape of the fourth surface 22 of the second prism 2, the optical performance of the projection display system can be improved, which is beneficial to improving the quality of the projected image.

[0068] In some examples of this application, the first surface 11 of the first prism 1 is a freeform surface or an aspherical surface.

[0069] When the first surface 11 of the first prism 1 is a freeform surface, the quality of the projected image can be improved.

[0070] Of course, the first surface 11 of the first prism 1 can also be an aspherical surface, which can reduce the processing difficulty and production cost of the lens.

[0071] In a preferred embodiment of this application, the first surface 11 of the first prism 1 and the fourth surface 22 of the second prism 2 can both be designed as freeform surfaces. This can further improve the quality of the projected image.

[0072] In some examples of this application, the incident surface 13 of the first prism 1 and the reflecting surface 23 of the second prism 2 are aspherical or freeform surfaces.

[0073] See some examples in this application. Figure 1 and Figure 2 The first surface 11 of the first prism 1 is a total internal reflection surface. During the process of light rays being projected from the incident surface 13 through the first prism 1 to the image source surface S1, the light undergoes two reflections, one of which is a total internal reflection and occurs on the first surface 11.

[0074] Specifically, see Figure 1 and Figure 2 The light incident on the incident surface 13 is defined, for example, as first linearly polarized light 01. The first linearly polarized light 01 enters the first prism 1, is totally reflected by the first surface 11, and then is directed toward the second surface 12. After being reflected by the beam splitter 5, it is emitted from the first surface 11 and directed toward the image source surface S1.

[0075] During the two reflection processes described above, the angle of incidence of the light rays entering the first prism 1 from the incident surface 13 and then striking the first surface 11 satisfies the condition of total internal reflection. Its function is to collimate the light rays entering through the incident surface 13.

[0076] According to the above example, in the illumination assembly, light is emitted after being reflected twice and then directed into the imaging assembly.

[0077] See some examples in this application. Figure 1 and Figure 2 The fourth surface 22 is a total internal reflection surface; the light undergoes four reflections during the process of being projected from the image source surface S1 to the projection surface S2, one of which is a total internal reflection and occurs on the fourth surface 22.

[0078] The image source surface S1 is provided with an LCOS display chip 4, as described above.

[0079] Specifically, the light incident on the image source surface S1, such as the LCOS display chip 4, forms a light beam carrying image information after the first reflection. This light beam then undergoes three more reflections before reaching the projection surface S2. Among the four reflections, one is a total internal reflection. The total internal reflection occurs on the fourth surface 22 of the second prism 2, meaning that the light beam satisfies the total internal reflection condition on the fourth surface.

[0080] According to the projection optical system provided in the embodiments of this application, light undergoes two total internal reflections (TIR) ​​as it propagates therein. See [link to relevant documentation]. Figure 1 .

[0081] See some examples in this application. Figure 2 The second surface 12 of the first prism 1 and the third surface 21 of the second prism 2 are glued together to form a glued prism.

[0082] According to the above example, the first prism 1 and the second prism 2 are glued together to form a glued prism. At this time, there is no air gap between the first prism 1 and the second prism 2.

[0083] Because air gaps increase the probability of light reflection or total internal reflection on the projection surface S2, resulting in light energy loss and even stray light generation, this application designs a first prism 1 and a second prism 2 that are glued together.

[0084] If the first prism 1 and the second prism 2 are not glued together, there may be large-angle light rays that cannot enter the second prism 2 due to total internal reflection by the first surface 11, which will affect the final projection image.

[0085] Therefore, it is evident that bonding the first prism 1 and the second prism 2 together in the entire projection display system is highly beneficial for the optical performance and optical architecture design of the projection display system.

[0086] In some examples of this application, when the light projected onto the incident surface 13 is natural light, a polarizer 7 is provided on the incident surface 13 to convert the natural light into linearly polarized light.

[0087] See Figure 1 and Figure 2 The projection display system includes the first prism 1 described above. To introduce illumination light, a light source 8 can be disposed on one side of the incident surface 13 of the first prism 1. Light for imaging display is emitted from the light source 8.

[0088] The light incident on the first prism 1 should, for example, be linearly polarized light.

[0089] Therefore, a polarizer 7 can be selectively introduced into the projection display system. Here, the polarizer 7 can be used to convert the illumination light projected by the light source 8 into linearly polarized light before it is incident on the first prism 1. That is, the polarizer 7 can form the illumination light emitted by the light source 8 into first linearly polarized light O1, such as S-polarized light, with polarization characteristics. See [reference needed]. Figure 1 .

[0090] It should be noted that after the polarizer 7 is introduced, it can be placed between the light source 8 and the incident surface 13 of the first prism 1. However, in order to simplify the assembly of the polarizer 7, in the above example, the polarizer 7 is directly placed on the incident surface 13 of the first prism 1 to convert the illumination light emitted by the light source 8 into linearly polarized light before it is incident into the first prism 1.

[0091] Of course, the polarizer 7 can also be disposed inside the light source 8, so that the light source 8 directly emits linearly polarized light to the first prism 1. This application does not limit this, as long as the illumination light projected into the first prism 1 is linearly polarized light.

[0092] In other words, after the light enters the second prism 2, it will first pass through its fourth surface 22 and enter the reflective element 3. The light will be reflected by the reflective element 3 and return to the surface where the first prism 1 and the second prism are bonded together, i.e., the beam-splitting surface. After that, the light will be reflected by the beam-splitting element 5 to the fourth surface 22. At this time, the angle of incidence when it hits the fourth surface 22 satisfies the condition of total internal reflection.

[0093] See some examples in this application. Figure 1 and Figure 2 The image source surface S1 reflects the first linearly polarized light O1 emitted from the first surface 11 to form a second linearly polarized light O2 with a changed polarization direction. The second linearly polarized light O2 passes through the beam splitter 5 and is directed towards the phase retarder 6. The phase retarder 6 converts the second linearly polarized light O2 into circularly polarized light O3 and then directs it towards the reflector 3. The reflector 3 reflects the circularly polarized light O3 to the third surface 21. When the circularly polarized light O3 passes through the phase retarder 6, it becomes the second linearly polarized light O2 again. It is then reflected by the beam splitter 5 to the phase retarder 6. The phase retarder 6 converts the second linearly polarized light O2 into circularly polarized light O3 and then directs it from the third surface 21 towards the fourth surface 22. The circularly polarized light O3 is totally reflected by the fourth surface 22 and then directed towards the reflector 23. The circularly polarized light O3 is reflected by the reflector 23 and then directed towards the projection surface S2.

[0094] According to the above example, in the imaging assembly, light is reflected at least four times before exiting to form a projected image. In the imaging assembly, the order of the four reflections is: reflective element 3, third surface 21 (PBS), fourth surface 22, and reflective surface 23. Total internal reflection occurs on the fourth surface.

[0095] In a specific example, the projection display system includes a first prism 1 and a second prism 2 bonded together (forming a bonded prism). Both the first prism 1 and the second prism 2 are freeform prisms. A beam splitter 5 and a phase delayer 6 are disposed between the two bonded surfaces of the first prism 1 and the second prism 2, which can be stacked to form a composite film. The first surface 11 of the first prism 1 and the fourth surface 22 of the second prism 2 are both freeform or aspherical surfaces and are total internal reflection surfaces.

[0096] The optical splitting element 5 is, for example, a semi-reflective and semi-permeable membrane (PBS).

[0097] For example, the beam splitter 5 can reflect first linearly polarized light 01 while transmitting second linearly polarized light 02. The first linearly polarized light 01 can be S-light, and the second linearly polarized light 02 can be P-light.

[0098] The phase delayer 6 is, for example, a quarter-wave plate (QWP).

[0099] For example, the phase delayer 6 can convert linearly polarized light into circularly polarized light O3, or convert circularly polarized light O3 into linearly polarized light. That is, it realizes the conversion between linearly polarized light and circularly polarized light.

[0100] The reflective element 3 is, for example, a reflector.

[0101] The reflective element 3 and the LCOS display chip 4 are positioned opposite each other. The projected light reflected from the LCOS display chip 4 can be modulated by the beam splitter 5 and the phase delayer 6 and then enter the reflective element 3. The reflective element 3 then reflects the incident projected light back into the second prism 2.

[0102] A high-reflectivity film can be provided on the reflective surface 23 of the second prism 2 to reflect all the light and project it to form an image. See [link to relevant documentation]. Figure 2 A projected image is formed at the position of the projection surface S2.

[0103] Based on the above example, combined with Figure 1 and Figure 2The illustrated optical architecture shows the LCOS display chip 4 and the reflective element 3 surrounding the cemented lens assembly formed by the first prism 1 and the second prism 2. The overall optical architecture has a compact layout. A near-eye optical system is formed based on freeform surface waveguide elements using the two cemented prisms.

[0104] According to the projection display system provided in the embodiments of this application, the optical path transmission path is as follows:

[0105] See Figure 1 and Figure 2 Illumination light, such as natural light, emitted from the light source 8 is incident perpendicularly onto the incident surface 13 of the first prism 1. The polarizer 7 on the incident surface 13 converts the natural light into first linearly polarized light O1 (e.g., S-beam). The first linearly polarized light O1, after being incident on the second surface 12, undergoes total internal reflection and redirects to the first surface 11. The first linearly polarized light O1 is reflected by the beam splitter 5 to the LCOS display chip 4, becoming projection light carrying image information. After the LCOS display chip 4 reflects the first linearly polarized light O1, the polarization direction of the first linearly polarized light O1 is changed to become second linearly polarized light O2 (e.g., P-beam). The beam splitter 5 can transmit the second linearly polarized light O2 (e.g., P-beam). The phase retarder 6 modulates the second linearly polarized light O2 (e.g., P-beam) into circularly polarized light O3 and then it enters the reflective element 3; the reflective element 3 reflects the circularly polarized light O3 and passes it through the phase retarder 6, which converts the circularly polarized light O3 into the first linearly polarized light O1 (e.g., S-beam); the beam splitter 5 reflects the first linearly polarized light O1 (e.g., S-beam) and passes it through the phase retarder 6 again, which modulates the first linearly polarized light O1 (e.g., S-beam) into circularly polarized light O3. The circularly polarized light O3 is totally reflected by the fourth surface 22 to the reflective surface 23; the reflective surface 23 reflects the circularly polarized light O3 to the projection surface S2 for projection imaging.

[0106] According to another embodiment of this application, a projection device is provided. The projection device includes: a housing and a projection display system as described in the first aspect.

[0107] The projection device includes, but is not limited to, AR head-mounted display (HMD) devices, and can also be vehicle-mounted projection devices and home micro-projection devices.

[0108] The specific implementation of the projection device provided in this application can refer to the various embodiments of the projection display system described above. Therefore, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, and will not be described in detail here.

[0109] The above embodiments mainly describe the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. For the sake of brevity, they will not be elaborated here.

[0110] While specific embodiments of this application have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of this application. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of this application. The scope of this application is defined by the appended claims.

Claims

1. A projection display system for projecting light rays projected onto an image source surface S1 onto a projection surface S2, characterized in that, include: A first prism (1) and a second prism (2), and a reflecting element (3), wherein the second prism (2) is located between the first prism (1) and the reflecting element (3), and at least one of the first prism (1) and the second prism (2) is a freeform prism; The first prism (1) includes a first surface (11) near the image source surface S1, a second surface (12) near the projection surface S2, and an incident surface (13) connected to the first surface (11) and the second surface (12), the incident surface (13) being used to allow light to enter the first prism (1); The second prism (2) includes a third surface (21) disposed close to the second surface (12), a fourth surface (22) disposed close to the reflective element (3), and a reflective surface (23) connected to the third surface (21) and the fourth surface (22). Among them, a beam splitting element (5) and a phase delayer (6) are disposed between the second surface (12) and the third surface (21), and the reflective element (3) is opposite to the image source surface S1 in position; The image source surface S1 reflects the first linearly polarized light (01) emitted from the first surface (11) to form a second linearly polarized light (02) with a changed polarization direction. After the second linearly polarized light (02) passes through the beam splitter (5), it is directed towards the phase retarder (6). The phase retarder (6) converts the second linearly polarized light (02) into circularly polarized light (03) and then directs it towards the reflector (3). The reflector (3) reflects the circularly polarized light (03) to the third surface (21). When the circularly polarized light (03) passes through the phase retarder (6), it becomes the second linearly polarized light (02) and is then reflected by the beam splitter (5) to the phase retarder (6). The phase retarder (6) converts the second linearly polarized light (02) into circularly polarized light (03) and then directs it from the third surface (21) towards the fourth surface (22). After the circularly polarized light (03) is totally reflected by the fourth surface (22), it is directed towards the reflector (23). The circularly polarized light (03) is reflected by the reflector (23), penetrates the fourth surface (22), and is directed towards the projection surface S2.

2. The projection display system according to claim 1, characterized in that, The projection display system also includes an LCOS display chip (4), and the location of the LCOS display chip (4) forms the image source surface S1.

3. The projection display system according to claim 1, characterized in that, The first prism (1) and the second prism (2) each include at least one freeform surface.

4. The projection display system according to any one of claims 1-3, characterized in that, The fourth surface (22) of the second prism (2) is a freeform surface.

5. The projection display system according to claim 4, characterized in that, The first surface (11) of the first prism (1) is a free-form surface or an aspherical surface.

6. The projection display system according to claim 5, characterized in that, The incident surface (13) of the first prism (1) and the reflecting surface (23) of the second prism (2) are aspherical or freeform surfaces.

7. The projection display system according to claim 5, characterized in that, The first surface (11) is a total light reflection surface; The light rays are projected from the incident surface (13) through the first prism (1) to the image source surface S1 and undergo two reflections, one of which is a total internal reflection and occurs on the first surface (11).

8. The projection display system according to claim 7, characterized in that, The fourth surface (22) is a total light reflection surface; The light undergoes four reflections as it is projected from the image source surface S1 to the projection surface S2, one of which is a total internal reflection and occurs on the fourth surface (22).

9. The projection display system according to claim 1, characterized in that, The second surface (12) of the first prism (1) and the third surface (21) of the second prism (2) are glued together to form a glued prism.

10. The projection display system according to claim 1, characterized in that, When the light projected onto the incident surface (13) is natural light, a polarizer (7) is provided on the incident surface (13) to convert the natural light into linearly polarized light.

11. A projection device, characterized in that, include: shell; and The projection display system as described in any one of claims 1-10.

Images