LCOS projection module

Abstract

The invention relates to the technical field of projection modules, and particularly discloses an LCOS (Liquid Crystal On Silicon) projection module, which comprises a light source module, a fly-eye lens, a polarization conversion sheet, a reflector, a relay lens assembly, a polarization beam splitter, an LCOS chip, a projection lens and a first linear polarizer which are sequentially arranged along a light transmission path, the projection lens is provided with a projection optical axis, and the light source optical axis is parallel to the projection optical axis, so that the projection lens is parallel to the light source module, and the LCOS projection module is ensured to meet the miniaturization design. The polarization conversion sheet is an integrated optical assembly which converts non-polarized light generated by the light source module into linearly polarized light in a single direction, and the polarization conversion sheet separates the non-polarized light emitted by the light source module and converts the non-polarized light into P polarized light in a single polarization state, so that the light utilization rate of the whole LCOS projection module is improved. The first linear polarizer is used for transmitting S polarized light and absorbing P polarized light, reducing stray light in a projected image and ensuring high contrast of the projected image.

Description

Technical Field

[0001] This invention relates to the field of projection module technology, and specifically to an LCOS projection module. Background Technology

[0002] With the improvement of people's consumption level, the application fields of projection modules are becoming increasingly widespread. In existing projection modules, LCOS (Liquid Crystal on Silicon) is usually used as the core display device. LCOS uses a silicon wafer as a substrate, on which liquid crystal molecules are integrated. By controlling the rotation angle of the liquid crystal molecules, the phase or polarization state of the incident polarized light is modulated, thereby realizing the grayscale and color display of the projected image.

[0003] However, existing LCOS projection modules are bulky due to their unreasonable structural layout. Furthermore, as users' demands for projection quality increase, traditional LCOS projection modules suffer from low light utilization and low contrast, severely impacting the quality of the projected image. Summary of the Invention

[0004] This invention discloses an LCOS projection module, the purpose of which is to at least solve one of the technical problems existing in the prior art.

[0005] This invention provides an LCOS projection module, comprising: a light source module having a light source optical axis, the light source module being used to emit light; a compound eye lens disposed along the light source optical axis on the light-emitting side of the light source module; a polarization converter disposed along the light source optical axis on the light-emitting side of the compound eye lens, the polarization converter being used to receive light from the compound eye lens and convert S-polarized light in the light into P-polarized light; a reflector disposed on the light-emitting side of the polarization converter and the reflector forming a 45° angle with the light source optical axis, the reflector being used to deflect the P-polarized light from the polarization converter; a relay lens assembly disposed on the light-emitting side of the reflector; and a polarization beam splitter disposed on the relay lens assembly. On the light-emitting side of the lens assembly, the polarizing beam splitter transmits P-polarized light and reflects S-polarized light; an LCOS chip is disposed on the light-emitting side of the polarizing beam splitter at a 45° angle to it, and is used to receive P-polarized light and convert it into S-polarized light, which is then directed toward the polarizing beam splitter; a projection lens is disposed on the light-emitting side of the polarizing beam splitter, and has a projection optical axis, and is used to receive S-polarized light reflected by the polarizing beam splitter; a first linear polarizer is disposed along the projection optical axis on the light-emitting side of the projection lens, and is used to transmit S-polarized light and absorb P-polarized light; wherein, the light source optical axis is parallel to the projection optical axis.

[0006] Further preferably, the LCOS projection module further includes a second linear polarizer, which is disposed between the relay lens assembly and the polarizing beam splitter. The second linear polarizer is used to transmit P-polarized light and absorb S-polarized light.

[0007] Further preferably, the LCOS projection module further includes a phase delay unit, which is disposed between the polarizing beam splitter and the LCOS chip, and is used to convert residual P-polarized light from the LCOS chip into S-polarized light.

[0008] Further preferably, the relay lens assembly includes two relay lenses with identical specifications: a first relay lens and a second relay lens. Both the first relay lens and the second relay lens have a structure with one side being flat and the other side being convex. The flat side of the first relay lens faces the reflector, and the flat side of the second relay lens faces the second linear polarizer. The convex sides of the first relay lens and the second relay lens are positioned close to each other. The focal length of both the first relay lens and the second relay lens is in the range of 70mm to 80mm.

[0009] Further preferably, the relay lens assembly has a relay optical axis, on which the center distance between the first relay lens and the second relay lens is 0.1mm to 1mm, and the distance between the center point of the plane of the first relay lens and the center point of the reflector is greater than 12.5mm.

[0010] Further preferably, the relay optical axis is perpendicular to the light source optical axis, the distance between the planes of the second linear polarizer and the second relay lens on the relay optical axis is greater than 0.5 mm, and the polarizing beam splitter is disposed on the relay optical axis and forms a 45° angle with the relay optical axis.

[0011] Further preferably, the light source module includes a blue light source, a green light source, a red light source, a green dichroic mirror, a red dichroic mirror, and three sets of collimating lens assemblies with identical specifications. The three sets of collimating lens assemblies are correspondingly positioned on the light-emitting sides of the blue light source, the green light source, and the red light source. The green dichroic mirror and the red dichroic mirror are both at a 45° angle to the optical axis of the light source and are spaced apart along the optical axis. The red dichroic mirror is closer to the compound eye lens. The blue light source is positioned on the optical axis of the light source and on the side of the green dichroic mirror away from the red dichroic mirror. The green light source is located below the green dichroic mirror along a direction perpendicular to the optical axis of the light source, and the red light source is located below the red dichroic mirror along a direction perpendicular to the optical axis of the light source.

[0012] Further preferably, the compound eye lens includes a first surface facing the red dichroic mirror and a second surface facing away from the first surface. Both the first surface and the second surface are provided with a plurality of microlens units. The sagittal height of the microlens units is 0.1 mm to 0.2 mm, and the distance between the first surface and the red dichroic mirror on the optical axis of the light source is 13 mm to 16 mm.

[0013] Further preferably, the collimating lens assembly includes a first collimating lens and a second collimating lens disposed along the light propagation path. The first collimating lens is close to the light source, and the combined focal length of the first collimating lens and the second collimating lens is 10.2 mm to 10.6 mm. The first collimating lens is a glass spherical lens with a refractive index Nd of 1.72 to 1.76, a dispersion coefficient Vd greater than 40, and a focal length of 9.5 mm to 9.8 mm. The second collimating lens is a glass aspherical lens with a refractive index Nd of 1.5 to 1.7, a dispersion coefficient Vd greater than 50, and a focal length of 14.2 mm to 16.4 mm.

[0014] More preferably, the total length of the projection lens is 100mm to 120mm, its effective focal length is 25mm to 29mm, its aperture value is F1.8 to 2.2, and the ratio of the long side to the short side of the projected image is 1.78:1.

[0015] Further preferably, the projection lens includes eight spherical glass lenses with optical power, arranged sequentially along the projection optical axis as a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens, wherein the first lens is close to the LCOS chip, and the diameter of the first lens is less than 43 mm, and the diameter of the fifth lens is less than 27 mm; the aperture stop of the projection lens is located between the third lens and the fourth lens, and the distance between the aperture stop and the second lens is 3 mm to 4 mm. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the LCOS projection module provided by the present invention; Figure 2 for Figure 1 Top view of the LCOS projection module in the image; Figure 3 for Figure 1 A front view of the LCOS projection module. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0018] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "top / bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0019] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "sleeved / connected," "connected," etc., should be interpreted broadly. For example, "connection" 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 an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0020] The LCOS projection module provided in the embodiments of this application will be further described in detail below with reference to the accompanying drawings.

[0021] like Figures 1 to 3 As shown, the LCOS projection module includes a light source module 1, a compound eye lens 2, a polarization converter 3, a reflector 4, a relay lens assembly 5, a polarization beam splitter 6, an LCOS chip 7, a projection lens 8, and a first linear polarizer 9 arranged sequentially along the light transmission path. The light source module 1 has a light source optical axis A and is used to emit light. The light is modulated along the light transmission path and then projected out by the projection lens 8 to form a projected image.

[0022] Specifically, the light source module 1 is used to emit light rays that travel along the light source optical axis A. The compound eye lens 2 is set on the light-emitting side of the light source module 1 along the light source optical axis A. The compound eye lens 2 receives the light rays from the light source module 1 and homogenizes the light rays to ensure that subsequent optical components can receive homogenized light rays.

[0023] like Figure 1 and Figure 2As shown, the polarization converter 3 is positioned along the optical axis A of the light source on the light-emitting side of the compound eye lens 2. The polarization converter 3 receives the light from the compound eye lens 2 and converts the S-polarized light in the light into P-polarized light. It should be noted that the light generated by the light source module 1 is a mixed light containing both S-polarized and P-polarized light. By placing the polarization converter 3 on the light-emitting side of the compound eye lens 2, it ensures that the P-polarized light in the homogenized light passes directly through, and that the S-polarized light in the homogenized light can be converted into P-polarized light before passing through, thereby improving the light utilization efficiency. It can be understood that the polarization converter 3 is an integrated optical component that converts the unpolarized light generated by the light source module 1 into linearly polarized light in a single direction. It separates the unpolarized light emitted by the light source module 1 (50% P-polarized light and 50% S-polarized light) and converts it into P-polarized light with a single polarization state, improving the light utilization rate of the subsequent LCOS chip 7, and thus improving the overall light utilization rate of the LCOS projection module.

[0024] Preferably, the polarization converter 3 is composed of a prism array with an angle of 45°, and a half-wave plate is attached above the prism array, which is used to convert the light into P-polarized light.

[0025] Furthermore, the reflector 4 is positioned on the light-emitting side of the polarization converter 3, and forms a 45° angle with the optical axis A of the light source. The reflector 4 is used to redirect the P-polarized light from the polarization converter 3, preventing the LCOS projection module from being a long strip structure arranged along the optical axis A of the light source. This shortens the length of the LCOS projection module and meets the requirements of miniaturization design. The reflector 4 is a flat plate structure, formed by depositing a reflective film on a glass substrate, thereby achieving the redirection of P-polarized light.

[0026] The relay lens assembly 5 is located on the light-emitting side of the reflector 4. The relay lens assembly 5 consists of multiple lenses with positive optical power, serving as an optical element responsible for relaying and transmitting light, image plane conversion, and beam adaptation. The core function of the relay lens assembly 5 is to optimize the propagation path and shape of light without altering the core image information, adapting to the overall optical path layout of the LCOS projection module and the requirements of the imaging device. This ensures high clarity, appropriate size, and minimal distortion of the projected image, ultimately ensuring that the light uniformly focused by the compound eye lens 2 can be refocused onto the LCOS chip 7.

[0027] A polarizing beam splitter 6 is positioned on the light-emitting side of the relay lens assembly 5. The polarizing beam splitter 6 transmits P-polarized light and reflects S-polarized light. It should be noted that P-polarized light incident from the relay lens assembly 5 to the polarizing beam splitter 6 can pass directly through the polarizing beam splitter 6, while S-polarized light incident from the LCOS chip 7 to the polarizing beam splitter 6 is reflected by the polarizing beam splitter 6. The polarizing beam splitter 6 is used for polarization separation and beam combining of light. P-polarized light in the incident light is transmitted, and S-polarized light is reflected. It also separates the S-polarized light modulated by the LCOS chip 7 (carrying image information) from the unmodulated light and guides it to the projection lens 8. Through the precise polarization selection of the polarizing beam splitter 6, background stray light is suppressed, achieving high contrast in the projected image. The polarizing beam splitter 6 has a flat plate structure. By coating different polarizing films on both sides of the glass substrate, it ensures that the polarizing beam splitter 6 can transmit P-polarized light and reflect S-polarized light from incident light on different sides.

[0028] The LCOS chip 7 is positioned on the light-emitting side of the polarizing beam splitter 6 at a 45° angle. The LCOS chip 7 receives P-polarized light and converts it into S-polarized light, which is then directed towards the polarizing beam splitter 6. The S-polarized light carries image information, ensuring that the final emitted light is capable of forming an image. It should be noted that LCOS chip 7 is short for Liquid Crystal on Silicon, a core device in reflective microdisplays. Essentially, it integrates a liquid crystal layer onto a silicon-based CMOS driver chip, modulating the incident P-polarized light to convert it into S-polarized light.

[0029] The projection lens 8 is positioned on the light-emitting side of the polarizing beam splitter 6, and is spaced apart from the LCOS chip 7, both facing the polarizing beam splitter 6. The projection lens 8 has a projection optical axis B, and is used to receive S-polarized light reflected by the polarizing beam splitter 6. The S-polarized light magnifies the projected image and exits through the projection lens 8. The light source optical axis A is parallel to the projection optical axis B, ensuring that the projection lens 8 is parallel to the light source module 1, thus guaranteeing the miniaturization of the LCOS projection module.

[0030] The first linear polarizer 9 is disposed along the projection optical axis B on the light-emitting side of the projection lens 8. The first linear polarizer 9 is used to transmit S-polarized light and absorb P-polarized light, thereby reducing stray light in the projected image and ensuring high contrast of the projected image.

[0031] By placing the polarization converter 3 along the light source optical axis A on the light-emitting side of the compound eye lens 2 and the light-receiving side of the reflector 4, this position is a critical node after light homogenization and before the optical path turning and subsequent polarization adjustment. After the compound eye lens 2 completes light homogenization, the light still contains a mixed state of S-polarized and P-polarized light. At this time, the polarization state is unified by the polarization converter 3, which can avoid the mixing of S-polarized light in the subsequent optical path and ensure the purity of the P-polarized light entering the reflector 4. At the same time, the first linear polarizer 9 is placed along the projection optical axis B on the light-emitting side of the projection lens 8 as the final polarization filtering node of the optical path. The projection lens 8 receives S-polarized light (effective imaging light) reflected by the polarization beam splitter 6, but due to the reflection / refraction deviation of the optical path components and the residual polarization conversion of the LCOS chip 7, a small amount of P-polarized light is inevitably mixed in. This position can complete the final stray light filtering before the imaging light is projected onto the screen, and finally ensure the polarization purity of the output light. Through the positional design and synergistic effect of polarization converter 3 and first linear polarizer 9, the two components achieve the dual effects of uniform incident polarization and zero outgoing stray light. Polarization converter 3 improves the purity of P-polarized light incident on polarization beam splitter 6 and LCOS chip 7, ensuring that LCOS chip 7 modulates only light of a single polarization state, reducing signal interference caused by invalid polarized light. Meanwhile, the first linear polarizer 9 filters out residual stray light at the end, completely cutting off the imaging path of P-polarized light, so that only high-purity S-polarized imaging light is displayed on the screen, which ultimately improves the high contrast of the LCOS projection module, achieving a contrast ratio of 800:1.

[0032] In some embodiments, the LCOS projection module further includes a second linear polarizer 10, which is disposed between the relay lens assembly 5 and the polarizing beam splitter 6. The second linear polarizer 10 transmits P-polarized light and absorbs S-polarized light, preventing stray S-polarized light from mixing with the light reaching the polarizing beam splitter 6. By distributing the second linear polarizer 10 between the light-emitting side of the relay lens assembly 5 and the light-incident side of the polarizing beam splitter 6, the target P-polarized light is allowed to pass through while blocking unmodulated S-polarized light, eliminating stray S-polarized light in the optical path, improving the contrast of the LCOS projection module, and ensuring that the projected image meets high contrast requirements.

[0033] In some embodiments, the LCOS projection module further includes a phase delay unit 20, which is disposed between the polarizing beam splitter 6 and the LCOS chip 7. The phase delay unit 20 is used to convert residual P-polarized light from the LCOS chip 7 into S-polarized light. It should be noted that due to the inherent characteristics of the polarization modulation working principle of the LCOS chip 7, it cannot achieve 100% polarization state conversion, that is, residual P-polarized light will exist in the light emitted from the LCOS chip 7. By adding the phase delay unit 20, it can be ensured that the residual P-polarized light in the light emitted from the LCOS chip 7 to the polarizing beam splitter 6 is converted into S-polarized light, so that the originally invalid stray polarized light is converted into effective imaging light, thereby improving the high contrast of the projected image. The phase delay unit 20, the polarization conversion plate 3, and the first linear polarizer 9 form a triple control. The polarization conversion plate 3 realizes the uniform polarization of the incident light, laying the foundation for the precise modulation of the LCOS chip 7; the phase delay unit 20 eliminates the inherent polarization residue of the LCOS chip 7 and reduces stray light sources; the first linear polarizer 9 filters the light leakage at the end, achieving final purification. The three components work together to solve the full-path polarization problem of front-end unification, mid-end correction, and end-end filtering, further improving polarization purity and light energy utilization, resulting in more significant contrast optimization of the projected image. This design is also fully compatible with the working principle of the LCOS chip 7. It can be understood that the phase delayer 20 is a half-wave plate, whose core function is to utilize its unique polarization modulation and phase delay characteristics to adapt to the core working principle of the LCOS chip 7's reflective polarization modulation, ultimately achieving precise polarization direction control, phase compensation, and improved light modulation efficiency.

[0034] In some embodiments, the relay lens assembly 5 includes two relay lenses, a first relay lens 51 and a second relay lens 52, with identical specifications. Both the first relay lens 51 and the second relay lens 52 have a structure with one side being flat and the other side being convex. It should be noted that the flat and convex surfaces of the first relay lens 51 and the second relay lens 52 refer to the surfaces along their optical path, i.e., the two surfaces through which the light passes. The flat surface of the first relay lens 51 faces the reflector 4, and the flat surface of the second relay lens 52 faces the second linear polarizer 10. The convex surfaces of the first relay lens 51 and the second relay lens 52 are positioned close to each other. The focal length of both the first relay lens 51 and the second relay lens 52 ranges from 70mm to 80mm. The flat surface of the first relay lens 51 facing the reflector 4 and the flat surface of the second relay lens 52 facing the second linear polarizer 10 serve as the incident / exit end face of the light, reducing the deviation of the refraction angle of the light at the end face. Furthermore, the planar ends of the first relay lens 51 and the second relay lens 52 allow the parallel P-polarized light, after being deflected by the reflector 4, to be perpendicularly incident on and exiting the relay lens assembly 5. This prevents the P-polarized light from diverging or converging due to the curvature of the end face, and also reduces the disturbance of the P-polarized light due to excessive light refraction angle. Simultaneously, the convex surfaces of the first relay lens 51 and the second relay lens 52 are positioned close to each other, forming a symmetrical converging transmission structure. This allows for precise convergence of the light incident through the first relay lens 51, followed by smooth output through the planar end of the second relay lens 52 to the second linear polarizer 10, avoiding light energy loss caused by the diffusion of P-polarized light during transmission. This surface layout also reduces the overall size of the assembly, adapting to a compact design where the light source optical axis A and the projection optical axis B are parallel, avoiding optical path layout conflicts caused by excessive lens space. The focal length range of the first relay lens 51 and the second relay lens 52 can ensure that the light is appropriately converged within the relay lens assembly 5, avoiding excessive light convergence and light spot distortion caused by too short a focal length, and preventing the light transmission distance from increasing, light energy attenuation and polarization state drift caused by too long a focal length.

[0035] In some embodiments, the relay lens assembly 5 has a relay optical axis C. The center distance between the first relay lens 51 and the second relay lens 52 on the relay optical axis C is 0.1mm to 1mm, and the distance between the center point of the plane of the first relay lens 51 and the center point of the reflector 4 is greater than 12.5mm. This allows light to be accurately projected onto the central region of the second linear polarizer 10 after being transmitted through the first relay lens 51 and the second relay lens 52, ensuring the subsequent polarization filtering and separation effect of the polarization beam splitter 6, and avoiding the increase of stray light caused by light deflection.

[0036] In some embodiments, the relay optical axis C is perpendicular to the light source optical axis A. The distance between the planes of the second linear polarizer 10 and the second relay lens 52 on the relay optical axis C is greater than 0.5 mm. This distance parameter provides adaptation space for light transmission and polarization filtering, avoiding interference between components and the generation of stray light. If the distance between the planes of the second linear polarizer 10 and the second relay lens 52 is too close, the stray light reflected from the surface of the second relay lens 52 will superimpose with the effectively transmitted light, interfering with the polarization filtering effect. The reserved distance allows the parallel P-polarized light emitted from the second relay lens 52 to be fully diffused and smoothly incident on the second linear polarizer 10, ensuring that the light covers the effective area of ​​the polarizer, avoiding the edge light from being mistakenly filtered due to the incident angle deviation, ensuring the uniformity of polarization filtering, and reserving reasonable tolerances for LCOS projection module assembly, improving mass production feasibility. The polarizing beam splitter 6 is set on the relay optical axis C and forms a 45° angle with the relay optical axis C, adapting to the 45° turning optical path design of the reflector, realizing precise switching of the light transmission direction. Preferably, when the relay optical axis C is perpendicular to the light source optical axis A, the light source module 1, the relay lens assembly 5, and the projection lens 8 form a "U" structure arrangement, further ensuring that the LCOS projection module meets the miniaturization design requirements.

[0037] When the relay optical axis C is perpendicular to the light source optical axis A, the first relay lens 51, the second relay lens 52, the second linear polarizer 10, and the LCOS chip 7 are arranged parallel to the relay optical axis C, making the LCOS projection module compact, the light path smooth, and avoiding the waste of some polarized light. Furthermore, the polarizing beam splitter 6 and the reflector 4 are both located on the relay optical axis C and form a 45° angle with it, ensuring that the light reflected by the reflector 4 can completely reach the polarizing beam splitter 6. Furthermore, the phase delayer 20 is located on the relay optical axis C and forms an acute angle with the surface of the LCOS chip 7, ensuring that the phase delayer adapts to the coaxial layout of the polarizing beam splitter 6 and the relay lens assembly 5, and ensuring the coaxiality and stability of the light path transmission. Meanwhile, the acute angle design allows the phase retarder 20 to adapt to the reflection characteristics of the LCOS chip 7, optimizing polarization correction efficiency and optical path compatibility. If the angle is 0° (parallel to the surface of the LCOS chip 7) or 90° (perpendicular to the surface of the LCOS chip 7), the reflected light reaching the phase retarder 20 is prone to superimposing with the incident light to form interference fringes, interfering with polarization state judgment and correction. That is, the acute angle allows the light reflected by the LCOS chip 7 to enter the phase retarder 20 along an offset but controllable path, ensuring that the corrected S-polarized light accurately returns to the polarization beam splitter 6 without interference stray light generation.

[0038] In some embodiments, the light source module 1 includes a blue light source 11, a green light source 12, a red light source 13, a green dichroic mirror 14, a red dichroic mirror 15, and three sets of collimating lens assemblies 16 with identical specifications. The three sets of collimating lens assemblies 16 are correspondingly arranged on the light-emitting side of the blue light source 11, the green light source 12, and the red light source 13. The green dichroic mirror 14 and the red dichroic mirror 15 are both at a 45° angle to the optical axis A of the light source and are spaced apart along the optical axis A. The red dichroic mirror 15 is closer to the compound eye lens 2. The blue light source 11 is located on the optical axis A of the light source and on the side of the green dichroic mirror 14 away from the red dichroic mirror 15. The green light source 12 is located below the green dichroic mirror 14 along the direction perpendicular to the optical axis A of the light source, and the red light source 13 is located below the red dichroic mirror 15 along the direction perpendicular to the optical axis A of the light source. The green dichroic mirror 14 achieves high reflectivity (typically greater than 99%) for green light (500nm-570nm) emitted by the green light source 12, while achieving high transmission (typically greater than 98.5%) for other wavelengths of light (such as red and blue light). The red dichroic mirror 15 achieves high reflectivity (typically greater than 98%) for red light (620nm-750nm), while achieving high transmission (typically greater than 98%) for other wavelengths of light (such as green and blue light). By setting the green dichroic mirror 14 and the red dichroic mirror 15, light of different wavelengths emitted by different light sources can be combined. The combined light exits from the red dichroic mirror 15 and enters the compound eye lens 2. Preferably, the blue light source 11, the green light source 12, and the red light source 13 are all LED light sources, each used to generate light of different wavelengths.

[0039] In some embodiments, the compound eye lens 2 includes a first surface 21 facing the red dichroic mirror 15 and a second surface 22 facing away from the first surface 21. Both the first surface 21 and the second surface 22 are provided with multiple microlens units, and the microlens units are spherical. The microlenses on the first surface 21 first decompose the combined light into multiple sub-rays, and the microlenses on the second surface 22 then re-superimpose and integrate the sub-rays, making the intensity and angular distribution of the emitted light more uniform, achieving secondary homogenization of the light and ensuring consistent polarization conversion. The sag of the microlens unit is 0.1mm to 0.2mm, which allows the microlens unit to achieve efficient light homogenization while controlling the light deflection angle within a reasonable range, avoiding polarization state disorder, and adapting to the polarization unification function of the subsequent polarization conversion sheet 3, reducing front-end polarization interference. Furthermore, the distance between the first surface 21 and the red dichroic mirror 15 on the optical axis A of the light source is 13mm to 16mm. That is, the distance between the center point of the first surface 21 and the center point of the red dichroic mirror 15 on the optical axis A of the source is 13mm to 16mm. This provides sufficient buffer space for the light rays coming out of the red dichroic mirror 15, allowing the light rays to diffuse fully and enter the first surface 21 of the compound eye lens 2 smoothly. This avoids the edge light rays being reflected or refracted and lost by the microlens unit due to the excessive incident angle. At the same time, it ensures that the light rays cover the effective area of ​​the microlens and maximizes the use of the uniform light area of ​​the compound eye lens 2.

[0040] In some embodiments, the collimating lens assembly 16 includes a first collimating lens 161 and a second collimating lens 162 disposed along the light propagation path. The first collimating lens 161 is close to the light source, that is, the first collimating lens 161 refers to the lens close to the blue light source 11, the green light source 12, or the red light source 13. The combined focal length of the first collimating lens 161 and the second collimating lens 162 is 10.2mm to 10.6mm, which precisely matches the light output requirements of the light source module 1. This avoids both excessive collimation and hot spots caused by an excessively short combined focal length, and insufficient parallelism and reduced light combining efficiency caused by an excessively long focal length.

[0041] Preferably, the first collimating lens 161 is a glass spherical lens with a refractive index Nd of 1.72–1.76, a dispersion coefficient Vd greater than 40, and a focal length of 9.5 mm–9.8 mm. The second collimating lens 162 is a glass aspherical lens with a refractive index Nd of 1.5–1.7, a dispersion coefficient Vd greater than 50, and a focal length of 14.2 mm–16.4 mm. The first collimating lens 161 uses a high refractive index and a low dispersion coefficient, while the second collimating lens 162 uses a low refractive index and a high dispersion coefficient. The two lenses complement each other in terms of dispersion, effectively correcting the chromatic aberration of the light source and ensuring accurate superposition of the three colors during subsequent light combining, avoiding color shifts and ultimately improving the purity of the combined light. Simultaneously, the difference in focal length between the first and second collimating lenses 161 allows for step-by-step convergence and collimation of the light, further improving beam parallelism. It should be noted that the light emitted by the blue light source 11, green light source 12 and red light source 13 has a divergence angle of about 120°. The collimating lens assembly 16, which consists of two glass lenses, is used to compress the light angle, which can improve the light energy utilization efficiency and meet the requirements of the subsequent homogenization process of the compound eye lens 2.

[0042] In some embodiments, the total length of the projection lens 8 is 100mm to 120mm, balancing imaging performance and module compactness. The effective focal length of the projection lens 8 is 25mm to 29mm. The effective focal length directly determines the size of the projected image and the projection distance, avoiding image distortion due to too short a focal length and insufficient projection distance due to too long a focal length (small spaces cannot display large images). The aperture value F of the projection lens 8 is 1.8 to 2.2, which can fully receive S-polarized light reflected by the polarizing beam splitter 6, avoiding a dark image and loss of details due to insufficient light intake. The ratio of the long side to the short side of the projected image of the projection lens 8 is 1.78:1, which can avoid pixel waste caused by image stretching or cropping, ensure the complete presentation of the image signal modulated by the chip, and adapt to the light distribution characteristics after front-end three-color light synthesis and light homogenization by the compound eye lens 2, so that the homogenized light can fully cover the lens imaging area and maximize the utilization of effective light energy.

[0043] In some embodiments, the projection lens 8 includes eight spherical glass lenses with optical power. Spherical lenses have advantages such as mature processing technology, controllable cost, and high yield, and can accurately correct multiple aberrations. Glass material has excellent optical stability and heat resistance, which can prevent lens deformation or decreased light transmittance caused by prolonged light exposure, ensuring the long-term reliability of the LCOS projection module. Along the projection optical axis B, the lenses are arranged in sequence: a first lens 101, a second lens, a third lens, a fourth lens, a fifth lens 105, a sixth lens, a seventh lens, and an eighth lens 108. The first lens 101 is close to the LCOS chip 7, and its diameter is less than 43mm, which avoids spatial interference with the LCOS chip 7 and the polarizing beam splitter 6, meeting the requirements of miniaturization design. The fifth lens 105 has a diameter of less than 27mm, which can both adapt to the light-gathering effect of the front lens and further reduce the overall size of the component, meeting the requirements of miniaturized LCOS projection modules, while also reducing the generation of stray light at the edge of the light output end. The aperture of the projection lens 8 is located between the third and fourth lenses, and the distance between the aperture and the second lens is 3mm to 4mm, which precisely controls the light intake range and improves the contrast and clarity of the image.

[0044] In some embodiments, the first lens 101 has positive optical power, and both of its surfaces on the projection optical axis B are convex. The second lens has positive optical power, and both of its surfaces on the projection optical axis B are convex. The third lens has positive optical power, and its two surfaces on the projection optical axis B are a convex surface and a flat surface, respectively. The fourth lens has positive optical power, and its two surfaces on the projection optical axis B are a convex surface and a flat surface, respectively. The eighth lens 108 has positive optical power, and its two surfaces on the projection optical axis B are a convex surface and a flat surface, respectively.

[0045] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and its improved concept, should be covered within the scope of protection of the present invention.

Claims

1. An LCOS projection module, characterized in that, include: A light source module, having a light source optical axis, is used to emit light; A compound eye lens is disposed on the light-emitting side of the light source module along the optical axis of the light source; A polarization converter is disposed along the optical axis of the light source on the light-emitting side of the compound eye lens. The polarization converter is used to receive light from the compound eye lens and convert S-polarized light in the light into P-polarized light. A reflector is disposed on the light-emitting side of the polarization converter, and the reflector forms a 45° angle with the optical axis of the light source. The reflector is used to redirect the P-polarized light from the polarization converter. A relay lens assembly is disposed on the light-emitting side of the reflector; A polarizing beam splitter is disposed on the light-emitting side of the relay lens assembly. The polarizing beam splitter is used to transmit P-polarized light and reflect S-polarized light. An LCOS chip is disposed on the light-emitting side of the polarizing beam splitter and at a 45° angle to the polarizing beam splitter. The LCOS chip is used to receive P-polarized light and convert it into S-polarized light, which is then directed toward the polarizing beam splitter. A projection lens is disposed on the light-emitting side of the polarizing beam splitter. The projection lens has a projection optical axis and is used to receive S-polarized light reflected by the polarizing beam splitter. A first linear polarizer is disposed along the projection optical axis on the light-emitting side of the projection lens. The first linear polarizer is used to transmit S-polarized light and absorb P-polarized light. The light source optical axis is parallel to the projection optical axis.

2. The LCOS projection module according to claim 1, characterized in that, The LCOS projection module also includes a second linear polarizer, which is disposed between the relay lens assembly and the polarizing beam splitter. The second linear polarizer is used to transmit P-polarized light and absorb S-polarized light.

3. The LCOS projection module according to claim 1, characterized in that, The LCOS projection module also includes a phase delayer, which is disposed between the polarizing beam splitter and the LCOS chip. The phase delayer is used to convert residual P-polarized light from the LCOS chip into S-polarized light.

4. The LCOS projection module according to claim 2, characterized in that, The relay lens assembly includes two relay lenses with identical specifications: a first relay lens and a second relay lens. Both the first and second relay lenses have a structure with one side being flat and the other side being convex. The flat side of the first relay lens faces the reflector, and the flat side of the second relay lens faces the second linear polarizer. The convex sides of the first and second relay lenses are positioned close to each other. The focal length of both the first and second relay lenses is in the range of 70mm to 80mm.

5. The LCOS projection module according to claim 4, characterized in that, The relay lens assembly has a relay optical axis, on which the center distance between the first relay lens and the second relay lens is 0.1mm to 1mm, and the distance between the center point of the plane of the first relay lens and the center point of the reflector is greater than 12.5mm.

6. The LCOS projection module according to claim 5, characterized in that, The relay optical axis is perpendicular to the light source optical axis, the distance between the planes of the second linear polarizer and the second relay lens on the relay optical axis is greater than 0.5 mm, and the polarizing beam splitter is disposed on the relay optical axis and forms a 45° angle with the relay optical axis.

7. The LCOS projection module according to claim 1, characterized in that, The light source module includes a blue light source, a green light source, a red light source, a green dichroic mirror, a red dichroic mirror, and three sets of collimating lens assemblies with identical specifications. The three sets of collimating lens assemblies are respectively arranged on the light-emitting side of the blue light source, the green light source, and the red light source. Both the green dichroic mirror and the red dichroic mirror are arranged at a 45° angle to the optical axis of the light source and are spaced apart along the optical axis of the light source. The red dichroic mirror is close to the compound eye lens. The blue light source is positioned on the optical axis of the light source and on the side of the green dichroic mirror away from the red dichroic mirror. The green light source is located below the green dichroic mirror along a direction perpendicular to the optical axis of the light source, and the red light source is located below the red dichroic mirror along a direction perpendicular to the optical axis of the light source.

8. The LCOS projection module according to claim 7, characterized in that, The compound eye lens includes a first surface facing the red dichroic mirror and a second surface facing away from the first surface. Both the first surface and the second surface are provided with a plurality of microlens units. The sagittal height of the microlens units is 0.1mm to 0.2mm, and the distance between the first surface and the red dichroic mirror on the optical axis of the light source is 13mm to 16mm.

9. The LCOS projection module according to claim 7, characterized in that, The collimating lens assembly includes a first collimating lens and a second collimating lens disposed along the light propagation path. The first collimating lens is close to the light source, and the combined focal length of the first collimating lens and the second collimating lens is 10.2 mm to 10.6 mm. The first collimating lens is a glass spherical lens with a refractive index Nd of 1.72 to 1.76, a dispersion coefficient Vd greater than 40, and a focal length of 9.5 mm to 9.8 mm. The second collimating lens is a glass aspherical lens with a refractive index Nd of 1.5 to 1.7, a dispersion coefficient Vd greater than 50, and a focal length of 14.2 mm to 16.4 mm.

10. The LCOS projection module according to claim 1, characterized in that, The projection lens has a total length of 100mm to 120mm, an effective focal length of 25mm to 29mm, an aperture value of F of 1.8 to 2.2, and a ratio of the long side to the short side of the projected image of 1.78:

1.

11. The LCOS projection module according to claim 10, characterized in that, The projection lens includes eight spherical glass lenses with optical power, and along the projection optical axis are the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens, wherein the first lens is close to the LCOS chip, and the diameter of the first lens is less than 43mm, and the diameter of the fifth lens is less than 27mm. The aperture stop of the projection lens is located between the third lens and the fourth lens, and the distance between the aperture stop and the second lens is 3mm to 4mm.

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