Projection display system and projection device

Abstract

Disclosed in embodiments of the present application are a projection display system and a projection device. The projection display system comprises a light source assembly, an imaging lens, and a polarizing beam splitting prism arranged between the light source assembly and the imaging lens. The imaging lens comprises a cemented lens, a reflector, and a single lens. The polarizing beam splitting prism has an incident surface and an exit surface which are opposite to one another, and a first surface and a second surface which are opposite to one another. The light source assembly is close to the incident surface, the cemented lens is close to the first surface, the reflector is close to the second surface, and the lens is close to the exit surface. The projection display system provided in embodiments of the present application has the characteristic of small size.

Description

Projection display system and projection device

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on September 13, 2023, with application number 202311184057.7 and invention name “A projection display system and projection device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application belongs to the field of optical projection technology, and specifically relates to a projection display system and a projection device. Background Art

[0003] AR technology integrates images into reality through optical methods to achieve augmented reality. AR displays project images onto the wearer's eyes using a projector. Image algorithms adjust the distance between the binocular images, creating a sense of distance. However, current projector solutions are bulky, hindering the lightweight design of AR products.

[0004] Summary of the Invention

[0005] The purpose of this application is to provide a new technical solution for a projection display system and a projection device.

[0006] According to a first aspect of the present application, a projection display system is provided. The projection display system includes a light source assembly, an imaging lens, and a polarization beam splitter prism disposed between the light source assembly and the imaging lens;

[0007] The imaging lens comprises a cemented mirror, a reflector and a single lens;

[0008] The polarization beam splitter prism has an incident surface and an exit surface opposite to each other, and a first surface and a second surface opposite to each other;

[0009] The light source assembly is close to the incident surface, the cemented mirror is close to the first surface, the reflector is close to the second surface, and the lens is close to the exit surface.

[0010] Optionally, all optical lenses in the composite mirror, the reflector and the lens are glass spherical lenses.

[0011] Optionally, the projection display system is configured to be able to at least partially replace the glued mirror, the reflector and the lens according to the FOV value.

[0012] Optionally, the projection display system further includes a polarization element, and the polarization element is arranged between the exit surface and the lens.

[0013] Optionally, the polarization element is a linear polarizer, and is arranged on the exit surface of the polarization beam splitter prism.

[0014] Optionally, the light source assembly includes a collimating assembly, a light homogenizing element and a relay lens arranged in sequence;

[0015] Wherein, the collimating component and the light homogenizing element are arranged along the same optical axis;

[0016] The relay lens and the incident surface of the polarization beam splitter prism are adjacent to each other and spaced apart.

[0017] Optionally, a reflective element is obliquely arranged between the light homogenizing element and the relay lens, and the reflective element is used to refract the light emitted from the light homogenizing element.

[0018] Optionally, the collimating assembly and the light homogenizing element are sequentially arranged along the first optical axis;

[0019] The relay lens is arranged along a second optical axis and is located on a reflection path of the reflection element. The second optical axis forms a target angle with the first optical axis.

[0020] Optionally, the effective focal length of the lens is 40 mm to 50 mm.

[0021] Optionally, the effective focal length of the reflector is between -8.5 mm and -7.5 mm.

[0022] Optionally, the effective focal length of the composite lens is 14 mm to 17 mm.

[0023] Optionally, the projection display system further comprises an LCOS chip, and the LCOS chip is arranged on a side of the laminated mirror away from the first surface;

[0024] The diagonal size of the LCOS chip is 5.5 mm to 6.5 mm.

[0025] Optionally, the distance between the center point of the effective area of ​​the LCOS chip and the center point of the convex surface of the reflector is 8.5 mm to 9.5 mm.

[0026] Optionally, the entrance pupil diameter of the projection display system is 2.5 mm to 3.5 mm.

[0027] Optionally, the distance between the center point of the reflector and the center point of the polarization beam splitter prism is 5.5 mm to 6.5 mm.

[0028] Optionally, the projection display system further comprises an illumination light source, which is configured to emit light of multiple different wavelength bands and project the light onto the light source assembly;

[0029] The distance between the light emitting center point of the illumination light source and the center point of the reflector is 5.5 mm to 6.5 mm.

[0030] Optionally, the total effective focal length of the imaging lens is 5.5 mm to 8.6 mm.

[0031] Optionally, the polarization beam splitter prism is composed of a first prism and a second prism glued to each other, and a beam splitter film glued between the first prism and the second prism.

[0032] According to a second aspect of the present application, a projection device is also provided. The projection device includes:

[0033] a housing; and

[0034] The projection display system as described in the first aspect.

[0035] The beneficial effects of this application are:

[0036] The projection display system proposed in the embodiment of the present application is a compact new optical architecture. Only one optical lens is provided on the exit surface side of the polarization beam splitter prism to achieve imaging. This can reduce the volume of the entire projection display system while ensuring the final projection effect.

[0037] Other features and advantages of the present application will become apparent from the following detailed description of exemplary embodiments of the present application with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only part of the drawings of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without any creative work.

[0039] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the application and, together with the description, serve to explain the principles of the application.

[0040] FIG1 is a schematic structural diagram of a projection display system provided in an embodiment of the present application;

[0041] FIG2 is one of the MTF curve diagrams of the projection display system provided in an embodiment of the present application;

[0042] FIG3 is one of the distortion diagrams of the projection display system provided in an embodiment of the present application;

[0043] FIG4 is one of the vertical axis chromatic aberration diagrams of the projection display system provided in an embodiment of the present application;

[0044] FIG5 is a second MTF curve diagram of the projection display system provided in an embodiment of the present application;

[0045] FIG6 is a second distortion diagram of the projection display system provided in an embodiment of the present application;

[0046] FIG. 7 is a second vertical axis chromatic aberration diagram of the projection display system provided in an embodiment of the present application.

[0047] Description of reference numerals:

[0048] 1. Illumination light source; 2. Collimation component; 3. Homogenizing element; 4. Reflecting element; 5. Relay lens; 6. Polarization beam splitter prism; 601. Incident surface; 602. Exit surface; 603. First surface; 604. Second surface; 7. LCOS chip; 8. Glued mirror; 9. Reflecting mirror; 10. Lens; 11. Polarization element. DETAILED DESCRIPTION

[0049] 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 arrangements of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0050] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present disclosure, its application, or uses.

[0051] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0052] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0053] It should be noted that like reference numerals and letters refer to like items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0054] The projection display system and projection device provided in the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0055] According to one aspect of the present application, a projection display system is provided, which can be applied to an AR device. Of course, the projection display system can also be applied to other types of projection devices.

[0056] The projection display system provided in an embodiment of the present application, as shown in FIG1 , includes a light source assembly, an imaging lens, and a polarizing beam splitter prism 6 disposed between the light source assembly and the imaging lens. The imaging lens includes a doublet mirror 8, a reflector 9, and a single lens 10. The polarizing beam splitter prism 6 has an opposing incident surface 601 and an exit surface 602, as well as opposing first and second surfaces 603 and 604. The light source assembly is located near the incident surface 601, the doublet mirror 8 is located near the first surface 603, the reflector 9 is located near the second surface 604, and the lens 10 is located near the exit surface 602.

[0057] According to the projection display system provided by the above embodiment, the entire optical architecture is arranged in a relatively compact manner. Referring to FIG1 , the light source assembly, especially the imaging lens, is arranged around the polarization beam splitter prism 6 . This arrangement helps to reduce the volume of the entire projection display system.

[0058] The projection display system of the embodiment of the present application provides a new projection optical architecture, in which only one lens 10 is provided on one side of the exit surface 602 of the polarization beam splitter prism 6. In the solution of the present application, the number of lenses involved in projection imaging is small, which can reduce the size and weight of the system.

[0059] According to the projection display system provided in the embodiments of the present application, the imaging lens, for example, includes a composite mirror 8, a reflector 9, and a lens 10, and these three optical elements are arranged on three sides of the polarization beam splitter prism 6. The composite mirror 8 has an imaging function. An imaging chip can be disposed on the side of the composite mirror 8 facing away from the polarization beam splitter prism 6. Light passing through the composite mirror 8 can be projected onto the imaging chip. The imaging chip has densely arranged pixels, which can be selectively controlled to convert the polarization states of S light and P light. The reflector 9 and the lens 10 both have an imaging function.

[0060] The glued lens 8 comprises, for example, two lenses glued together, which can eliminate imaging chromatic aberration and is easy to assemble as a whole optical device.

[0061] The polarization beam splitter prism 6 is formed by gluing two triangular prisms together with a beam splitting film disposed therebetween, and can reflect S light and transmit P light.

[0062] The projection display system proposed in the embodiment of the present application is a compact new optical architecture. Only one optical lens is provided on the side of the exit surface 602 of the polarization beam splitter prism 6 to realize imaging. This can reduce the volume of the entire projection display system while ensuring the final projection effect.

[0063] As shown in Figures 2 and 5 , the projection display system's center field MTF is >0.5 at 167 lp / mm. As shown in Figures 3 and 6 , the system's maximum distortion occurs within one field of view, with an absolute value of less than 25%. As shown in Figures 4 and 7 , the system's maximum chromatic aberration is less than 250 μm. The overall projection display system delivers excellent final projection quality.

[0064] In some examples of the present application, all optical lenses in the cemented mirror 8, the reflector 9 and the lens 10 are glass spherical lenses.

[0065] According to the above example, all lenses in the imaging lens can be spherical lenses, which can improve optical performance and reduce costs.

[0066] Optionally, all optical lenses in the imaging lens may be made of glass, which can improve the temperature resistance of the entire projection display system.

[0067] In some examples of the present application, the projection display system is configured to be able to at least partially replace the cemented mirror 8, the reflective mirror 9, and the lens 10 according to the FOV value.

[0068] According to the projection display system provided in the embodiments of the present application, the light source assembly, polarization beam splitter prism 6, and imaging chip can be shared / common components. Based on this, the FOV value of the entire projection display system can be changed by replacing some or all of the lenses in the imaging lens.

[0069] It can be understood that, referring to FIG1 , the surface shapes and parameters of all optical lenses included in the imaging lens can be designed accordingly according to different FOV value requirements.

[0070] Since the optical lenses used in the imaging lens are all glass spherical lenses, their development costs are relatively low (usually between 5,000 and 7,000), which can reduce the production cost of the projection display system.

[0071] It should be noted that the projection display system provided in the embodiment of the present application can meet the requirements of FOV values ​​ranging from 40° to 56°. To meet different FOV requirements, it is only necessary to change the optical lens in the imaging lens.

[0072] The embodiments of the present application provide an optical architecture that is compatible with different FOVs, which can transform the FOV of the projection display system at the lowest development cost to meet the needs of different users for different FOVs.

[0073] In some examples of the present application, referring to FIG. 1 , the projection display system further includes a polarization element 11 , which is disposed between the exit surface 602 and the lens 10 .

[0074] According to the above example, by introducing a polarizing element 11 between the exit surface 602 of the polarization beam splitter 6 and the single lens 10, the P light in the exiting light can be filtered out and the S light can be allowed to pass, thereby ensuring the final projection effect.

[0075] In one example, the polarization element 11 is a linear polarizer, and is disposed on the exit surface 602 of the polarization beam splitter prism 6 .

[0076] The polarizing element 11 is a linear polarizer, which can be used to separate light into S light and P light, and transmit the S light and reflect the P light.

[0077] The polarization element 11 is directly mounted on the exit surface 602 of the polarization beam splitter 6, which can reduce the difficulty of assembling the polarization element. This design in the present application filters out the P light before the projection light is finally emitted, allowing the S light to pass through, thereby ensuring the final projection effect.

[0078] In some examples of the present application, referring to FIG1 , the light source assembly includes a collimating assembly 2, a light homogenizing element 3, and a relay lens 5 arranged in sequence; wherein the collimating assembly 2 and the light homogenizing element 3 are arranged along the same optical axis; the incident surface 601 of the relay lens 5 and the polarization beam splitter prism 6 are adjacent and spaced apart.

[0079] The collimating component 2 has a certain convergence effect, and can convert the divergent light into parallel collimated light.

[0080] Optionally, referring to FIG1 , the collimating assembly 2 includes two collimating lenses.

[0081] Of course, depending on the light source, the collimating component 2 can also be a light-receiving device such as a microlens array or a reflective bowl array, which can be used to achieve the purpose of collimating the light.

[0082] The light homogenizing element 3 is, for example, a fly-eye lens, which has certain light homogenizing and shaping effects, can improve the brightness uniformity of the light spot, and change the circular light spot into a rectangular light spot.

[0083] It should be noted that the light homogenizing element 3 includes but is not limited to the above-mentioned fly-eye lens, and can also be other light homogenizing devices, which is not limited in this application.

[0084] The relay lens 5 is used to converge the light into the polarization beam splitter prism 6 at the rear.

[0085] It should be noted that by changing the focal length of the relay lens 5 , the size of the light spot projected onto the imaging chip, such as the LCOS chip, can be controlled.

[0086] In some examples of the present application, referring to FIG. 1 , a reflective element 4 is obliquely disposed between the light homogenizing element 3 and the relay lens 5 , and the reflective element 4 is used to refract the light emitted from the light homogenizing element 3 .

[0087] According to the above example, by introducing a reflective element 4 between the light homogenizing element 3 and the relay lens 5, the light homogenizing element 3 and the relay lens 5 can be set in two directions. This design is conducive to reducing the axial size of the entire light source assembly, thereby reducing the volume of the entire projection display system.

[0088] In some examples of the present application, referring to FIG1 , the collimating assembly 2 and the light homogenizing element 3 are sequentially arranged along the first optical axis; the relay lens 5 is arranged along the second optical axis and is located on the reflection path of the reflection element 4, and the second optical axis forms a target angle with the first optical axis.

[0089] According to the above example, the collimating component 2 and the light homogenizing element 3 can be designed to be arranged in sequence along the first optical axis, and the relay lens 5 can be arranged on the second optical axis with the help of the deflection effect of the reflective element 4 on the light. The first optical axis and the second optical axis form an angle of 90°, for example, which is conducive to reducing the volume of the entire projection display system.

[0090] The reflective element 4 is, for example, a reflector.

[0091] The reflective element 4 is arranged at an angle of 45° on the light output path of the light homogenizing element 3 , and is responsible for rotating the light by 90° and then projecting it to the relay lens 5 .

[0092] In some examples of the present application, the effective focal length of the lens 10 is 40 mm to 50 mm.

[0093] 1 , only one lens 10 is provided on one side of the exit surface 602 of the polarization beam splitter prism 6. When the effective focal length of the lens 10 is 40 mm to 50 mm, it can effectively converge light and correct spherical aberration, thereby improving the quality of the projected image.

[0094] In some examples of the present application, the effective focal length of the reflector 9 is between -8.5 mm and -7.5 mm.

[0095] The reflector 9 is located on the second surface 604 of the polarization beam splitter prism 6 . Referring to FIG. 1 , the reflector 9 is located on one side of the upper surface of the polarization beam splitter prism 6 and is used to reflect light.

[0096] The reflector 9 provided in the above example can provide a larger optical focal length for the projection display system, thereby improving the clarity of the projected image.

[0097] It should be noted that, based on the effective focal length range of the reflector 9 provided in the above example, the reflector 9 itself can provide a large positive focal power, which does not introduce chromatic aberration, spherical aberration, or excessive aberration during the projection imaging process, thereby improving the optical performance of the projection display system.

[0098] In some examples of the present application, the effective focal length of the cemented mirror 8 is 14 mm to 17 mm.

[0099] According to the above example, referring to FIG1 , a bonding mirror 8 is provided on one side of the first surface 603 of the polarizing beam splitter prism 6. This bonding mirror 8 transmits light to the adjacent imaging chip, thereby eliminating chromatic aberration in the image. Furthermore, the bonding mirror 8 is relatively simple to assemble, allowing for the simultaneous placement of multiple lenses in a single assembly, thereby improving production efficiency and enhancing product yield.

[0100] In some examples of the present application, the projection display system further includes an LCOS chip 7, which is disposed on a side of the glued mirror 8 facing away from the first surface 603; a diagonal size of the LCOS chip 7 is 5.5 mm to 6.5 mm.

[0101] According to the above example, by reducing the size of the LCOS chip, the volume of the entire projection display system can be reduced. In this application, the relay lens 5 is introduced to achieve the problem of matching the light modulation component with the small-sized LCOS chip.

[0102] The LCOS chip 7 can form an image source surface, which can reflect the projected light to the projection surface (located on the side of the lens 10 away from the exit surface 602) for projection imaging.

[0103] In some examples of the present application, the distance between the center point of the active area of ​​the LCOS chip 7 and the center point of the convex surface of the reflector 9 is 8.5 mm to 9.5 mm.

[0104] According to the above example, by constraining the positions of the LCOS chip and the reflector 9 , it is beneficial to reduce the volume of the entire projection display system while ensuring the imaging quality.

[0105] In some examples of the present application, the entrance pupil diameter of the projection display system is 2.5 mm to 3.5 mm.

[0106] According to the above example, by controlling the range of the entrance pupil diameter of the projection display system, good projection imaging quality can be achieved within a certain field of view range, such as 40° to 56°. The entire projection display system has excellent optical performance.

[0107] In some examples of the present application, the distance between the center point of the reflector 9 and the center point of the polarization beam splitter prism 6 is 5.5 mm to 6.5 mm.

[0108] According to the above example, by constraining the position of the reflector 9 relative to the polarization beam splitter prism 6 , it is beneficial to reduce the volume of the projection display system while ensuring the imaging quality.

[0109] In some examples of the present application, referring to FIG1 , the projection display system further includes an illumination light source 1, which is used to emit light of multiple different wavelength bands and project them onto the light source assembly; the distance between the light emitting center point of the illumination light source 1 and the center point of the reflector 9 is 5.5 mm to 6.5 mm.

[0110] According to the projection display system provided by the embodiment of the present application, the introduced illumination light source 1 can be a multi-color LED, for example, it can emit RGB three-color light, so as to form a colorful projection image.

[0111] The projection display system provided in the embodiments of this application utilizes a single LED light source, which can emit, for example, RGB light, significantly reducing the volume of the illumination component. For a dual-channel projection system with the same light-emitting chip size and field of view (FOV), the volume is approximately 2.5 to 2.9 cc. However, the projection display system provided in the embodiments of this application has a volume of 1.1 to 1.4 cc, a reduction of approximately 52% to 56%.

[0112] In some examples of the present application, the total effective focal length of the imaging lens is 5.5 mm to 8.6 mm.

[0113] The projection display system provided in the embodiments of the present application can realize short-focus projection imaging.

[0114] In some examples of the present application, as shown in FIG1 , the polarization beam splitter prism 6 is composed of a first prism and a second prism bonded together, and a beam splitter film bonded between the first prism and the second prism. The polarization beam splitter prism 6 can transmit S light and reflect P light.

[0115] The projection display system is described below through Examples 1 to 4.

[0116] The projection display systems provided in the following embodiments 1 to 4 all adopt the same projection optical architecture, as shown in FIG1 , and include: an illumination light source 1, a light source assembly, an imaging lens, an LCOS chip 7, and a polarization beam splitter prism 6 disposed between the light source assembly and the imaging lens;

[0117] The imaging lens includes a cemented mirror 8 , a reflective mirror 9 and a single lens 10 .

[0118] The polarization beam splitter prism 6 includes a beam splitter film, and has an incident surface 601 and an exit surface 602 opposite to each other, and a first surface 603 and a second surface 604 opposite to each other;

[0119] The light source assembly is close to the incident surface 601, the imaging chip 7 and the cemented mirror 8 are close to the first surface 603, the reflector 9 is close to the second surface 604, the single lens 10 is close to the exit surface 602, and a polarizing element 11 is mounted on the exit surface 602;

[0120] The light source assembly includes a collimating assembly 2, a light homogenizing element 3, a reflecting element 4 and a relay lens 5; the collimating assembly 2 and the light homogenizing element 3 are arranged in sequence along the first optical axis; the reflecting element 4 is arranged at an angle of 45° between the light homogenizing element 3 and the relay lens 5, and is used to fold the light emitted by the light homogenizing element 3 by 90°; the relay lens 5 is close to the incident surface 601 and is arranged along the second optical axis, and the second optical axis forms a 90° angle with the first optical axis.

[0121] Table 1 below shows parameters of optical elements that can be shared by Examples 1 to 4.

[0122] Table 1

[0123] According to Table 1 above, referring to FIG1 , the front surface of the composite lens 8 is the surface close to the illumination light source 1 , and the rear surface is the surface away from the illumination light source 1 . The first composite lens and the second composite lens are two lenses that make up the composite lens 8 .

[0124] Based on the optical architecture of the projection display system shown in FIG1 and the optical parameters shown in Table 1 above, the optical performance of the projection display system is described as follows:

[0125] 2 to 4 , the optical performance of the projection display systems provided in Examples 1 and 2 are shown. FIG2 is an MTF curve diagram of the projection display system, FIG3 is a distortion diagram of the projection display system, and FIG4 is a vertical axis chromatic aberration diagram of the projection display system.

[0126] The MTF curve is a modulation transfer function graph that measures the image clarity of a near-eye optical system by comparing the contrast between black and white line pairs. As shown in Figure 2, the center field MTF is >0.5 at 167 lp / mm, indicating a clear image.

[0127] As shown in FIG3 , the maximum distortion occurs in 1 field of view, and the absolute value is less than 20%.

[0128] Vertical axial chromatic aberration, also known as chromatic aberration of magnification, primarily refers to the difference in the focal positions of blue and red light on the image plane, caused by the dispersion of a single, multi-colored principal ray on the object side due to the refraction system. As shown in Figure 4, the maximum chromatic aberration in a projection display system is less than 180μm.

[0129] 5 to 7 , the optical performance of the projection display systems provided in Examples 3 and 4 are shown. FIG5 is an MTF curve diagram of the projection display system, FIG6 is a distortion diagram of the projection display system, and FIG7 is a vertical axis chromatic aberration diagram of the projection display system.

[0130] The MTF curve, a modulation transfer function, measures the image clarity of a near-eye optical system by measuring the contrast between black and white line pairs. As shown in Figure 5, the center field MTF is >0.5 at 167 lp / mm, indicating a clear image.

[0131] As shown in FIG6 , the maximum distortion occurs in the first field of view, and the absolute value is less than 25%.

[0132] Vertical chromatic aberration, also known as chromatic aberration of magnification, primarily refers to the difference in focal position between blue and red light on the image plane, caused by the dispersion of a single, multi-colored principal ray on the object side. As shown in Figure 7, the maximum chromatic aberration in a projection display system is less than 250μm.

[0133] The projection display system provided in the embodiment of the present application can form a projection light engine, for example.

[0134] On the other hand, an embodiment of the present application further provides a projection device, which includes a housing and the projection display system described above.

[0135] The above-mentioned projection device can be, for example, a head-mounted display device, such as AR smart glasses or an AR smart helmet.

[0136] The specific implementation of the projection device of the embodiment of the present application can refer to the embodiment of the projection display system described above, and therefore at least has all the beneficial effects brought by the technical solutions of the above embodiments, which will not be described in detail here.

[0137] Although some specific embodiments of the present application have been described in detail by way of examples, it should be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present application. It should be understood by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. A projection display system, characterized in that: It comprises a light source assembly, an imaging lens, and a polarization beam splitter prism (6) arranged between the light source assembly and the imaging lens; The imaging lens comprises a cemented mirror (8), a reflecting mirror (9) and a single lens (10); The polarization beam splitting prism (6) has an incident surface (601) and an exit surface (602) opposite to each other, and a first surface (603) and a second surface (604) opposite to each other; The light source assembly is close to the incident surface (601), the cemented mirror (8) is close to the first surface (603), the reflector (9) is close to the second surface (604), and the lens (10) is close to the exit surface (602).

2. The projection display system according to claim 1, characterized in that: All optical lenses in the cemented mirror (8), the reflector (9) and the lens (10) are glass spherical lenses.

3. The projection display system according to claim 1 or 2, characterized in that: The projection display system is configured to be able to at least partially replace the glued mirror (8), the reflective mirror (9) and the lens (10) according to the FOV value.

4. The projection display system according to claim 1, characterized in that: The projection display system further comprises a polarization element (11), wherein the polarization element (11) is arranged between the exit surface (602) and the lens (10).

5. The projection display system according to claim 4, characterized in that: The polarization element (11) is a linear polarizer and is arranged on the exit surface (602) of the polarization beam splitting prism (6).

6. The projection display system according to claim 1, characterized in that the light source assembly comprises a collimating assembly (2), a light homogenizing element (3) and a relay lens (5) which are arranged in sequence; in, The collimating component (2) and the light homogenizing element (3) are arranged along the same optical axis; The relay lens (5) and the incident surface (601) of the polarization beam splitting prism (6) are adjacent to each other and are arranged at intervals.

7. The projection display system according to claim 6, characterized in that: A reflective element (4) is obliquely arranged between the light homogenizing element (3) and the relay lens (5), and the reflective element (4) is used to refract the light emitted from the light homogenizing element (3).

8. The projection display system according to claim 7, characterized in that: The collimating component (2) and the light homogenizing element (3) are arranged in sequence along the first optical axis; The relay lens (5) is arranged along a second optical axis and is located on a reflection path of the reflection element (4); the second optical axis forms a target angle with the first optical axis.

9. The projection display system according to claim 1, characterized in that: The effective focal length of the lens (10) is 40 mm to 50 mm.

10. The projection display system according to claim 1, characterized in that: The effective focal length of the reflector (9) is between -8.5 mm and -7.5 mm.

11. The projection display system according to claim 1, characterized in that: The effective focal length of the cemented mirror (8) is 14 mm to 17 mm.

12. The projection display system according to claim 1, characterized in that: The projection display system further comprises an LCOS chip (7), wherein the LCOS chip (7) is arranged on a side of the glued mirror (8) facing away from the first surface (603); The diagonal size of the LCOS chip (7) is 5.5 mm to 6.5 mm.

13. The projection display system according to claim 12, characterized in that: The distance between the center point of the effective area of ​​the LCOS chip (7) and the center point of the convex surface of the reflector (9) is 8.5 mm to 9.5 mm.

14. The projection display system according to claim 1, characterized in that: The entrance pupil diameter of the projection display system is 2.5 mm to 3.5 mm.

15. The projection display system according to claim 1, characterized in that: The distance between the center point of the reflector (9) and the center point of the polarization beam splitting prism (6) is 5.5 mm to 6.5 mm.

16. The projection display system according to claim 1, characterized in that: The projection display system further comprises an illumination light source (1), wherein the illumination light source (1) is used to emit light of multiple different wavelength bands and project the light onto the light source assembly; The distance between the light emitting center point of the illumination light source (1) and the center point of the reflector (9) is 5.5 mm to 6.5 mm.

17. The projection display system according to claim 1, characterized in that: The total effective focal length of the imaging lens is 5.5 mm to 8.6 mm.

18. The projection display system according to claim 1, characterized in that: The polarization beam splitter prism (6) is composed of a first prism and a second prism glued to each other, and a beam splitter film glued between the first prism and the second prism.

19. A projection device, characterized in that: include: case; as well as A projection display system as claimed in any one of claims 1 to 18.

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