Projection module

Abstract

A projection module comprises a projection unit (30), an adjustment unit (10) and an optical unit (20), the optical unit (20) comprises at least one optical lens (211) and a polarization element (212), and the polarization element (212) is arranged on the rear side of the projection unit (30). Wherein the polarization element (212) is arranged between the optical lenses (211), a light signal emitted by the projection unit (30) is emitted through the optical lenses (211) under the action of multiple refraction and / or reflection of the polarization element (212), the adjustment unit (10) can correspondingly adjust the distance between the optical lenses (211), and the adjustment unit (10) and the polarization element (212) are matched with each other to adjust the distance between the optical lenses (211). By prolonging the light path passing through the optical lens (211), the display with large exit pupil diameter, short focus and high optical performance is realized.

Description

A projection module Technical Field

[0001] The present invention relates to the field of virtual reality projection modules, and in particular to an augmented reality projection module. Background Art

[0002] A virtual head-mounted display (HMD) is a visual optical system that projects images or data from a microdisplay into the human eye pupil. Based on the projection method, HMDs are categorized as eyepiece-based and projection-based. Eyepiece-based HMDs place the image within the focal length of the optical system to produce a magnified virtual image, which is then refracted or reflected by a subsequent lens system to form the system's exit pupil at the eye's pupil. This exit pupil position coincides with the optical system's aperture stop. Projection-based HMDs, on the other hand, use an optical system (primarily precision optical lenses) to magnify the image on the microdisplay, projecting it onto the retina, presenting the viewer with a large-screen image.

[0003] Currently, both eyepiece-based and projection-based head-mounted displays require users to position the device at their eyes to better receive the light signals emitted by the projection unit. While the optical lenses used in existing head-mounted displays can effectively improve the imaging quality of the displays, they are bulky and heavy. Wearing them for extended periods can cause discomfort, negatively impacting the user experience.

[0004] The miniaturization of head-mounted displays is the current mainstream development trend, and the projection module, as an important component of the head-mounted display, also needs to be miniaturized accordingly.

[0005] Summary of the Invention

[0006] As an important component of the head-mounted display, the camera module includes a projection unit, a lens unit and an adjustment unit. The light signal emitted by the projection unit is received by the human eye through the action of the lens unit. The adjustment unit can adjust the gap between each lens piece in the lens unit, thereby adjusting the image clarity according to actual conditions.

[0007] Furthermore, in order for the light signal emitted by the projection module to pass through the lens unit and form a clear image, it is necessary to provide a certain amount of adjustment gap between the lens pieces of the lens unit, and at the same time, there must be a certain amount of gap between the lens pieces themselves to meet the imaging requirements. This lens unit will increase the height of the camera module, and when the camera module equipped with the lens unit is subsequently fixed to the head-mounted display, the volume of the display will increase. To address the above issues, the present application provides a camera module that can effectively achieve miniaturization of the camera module to meet user needs.

[0008] One of the embodiments of the present application provides a projection module, which can effectively improve the imaging quality of the projection module by fixing the first optical lens and the second optical lens and adjusting the gap between the second optical lens and the third optical lens.

[0009] One of the embodiments of the present application provides a projection module, in which the polarization element is directly integrated on the optical lens by coating, which can effectively shorten the focal length of the optical system while meeting the imaging requirements of the optical system.

[0010] One of the embodiments of the present application provides a projection module, which integrates the 1 / 4 wave plate on the second optical lens. By calibrating the position between the first optical lens and the second optical lens to adjust the installation position of the 1 / 4 wave plate, the installation accuracy of the 1 / 4 wave plate can be effectively improved.

[0011] One of the embodiments of the present application provides a projection module, in which the two opposite surfaces of the first optical lens and the second optical lens are set as a planar structure, which can facilitate the coating setting between the first optical lens and the second optical lens, thereby extending the propagation path of the projection light.

[0012] One embodiment of the present application provides a projection module, in which a cover is fixed at the position where the rotating ring is connected to the lens barrel, thereby preventing the rotating ring from excessively moving relative to the lens barrel and preventing external dust from entering the gap between the lens barrel and the rotating ring.

[0013] One of the embodiments of the present application provides a projection module, in which a through hole with a certain inclination angle to the bottom surface of the lens barrel is provided on the lens barrel, and the third optical lens is connected to the rotating ring through the mediation of a fastener. When the rotating ring moves along the direction of the optical axis, it can drive the third optical lens to move, thereby realizing the adjustment of the position of the third optical lens.

[0014] One of the embodiments of the present application provides a projection module, in which a vertical groove structure is arranged inside a rotating ring. Through a preset through hole on the lens barrel, the vertical groove and the third optical lens produce a corresponding linkage effect. The position of the third optical lens can be achieved by adjusting the external rotating ring, thereby simplifying the structure of the adjustment unit.

[0015] One of the embodiments of the present application provides a projection module, which can effectively simplify the assembly process by setting a corresponding step-like structure inside the lens barrel, fixing the optical lens on the step-like structure, and reserving a gap between each lens by the height of the step.

[0016] One of the embodiments of the present application provides a projection module, in which a semi-reflective and semi-transparent film in a polarizing element is set on the surface of a third optical lens, so that the light projected from the projection unit first passes through the third optical lens, which can effectively improve the utilization rate of the projected light.

[0017] One of the embodiments of the present application provides a projection module, in which the second optical lens is made of a material with a low refractive index, so that the projection light passing through the second optical lens can be reflected again to the third optical lens, thereby extending the propagation path of the projection light.

[0018] The present application provides a projection module, which introduces a polarization element into the optical lens structure, thereby shortening the focal length of the entire optical system while realizing imaging of the optical system, thereby miniaturizing the overall structure of the projection module.

[0019] In order to achieve the above objectives, the technical solutions adopted in this application are:

[0020] A projection module includes a projection unit, an adjustment unit, and an optical unit. The projection light emitted by the projection unit can be emitted through the optical unit. The optical unit is arranged inside the adjustment unit.

[0021] The optical unit further includes at least one optical lens and at least one polarizing element, wherein the polarizing element is mainly used to change the propagation path of the projection light, and the polarizing element is arranged between the optical lenses;

[0022] There are multiple optical lenses, including a first optical lens, a second optical lens, and a third optical lens, wherein the first optical lens and the second optical lens constitute a fixed lens group and are fixedly disposed on the adjustment unit, and the third optical lens is movably disposed on the adjustment unit for focusing, the surface of the first optical lens facing the projection unit is planar, and some elements of the polarization element are disposed between the first optical lens and the second optical lens; characterized in that:

[0023] The adjustment unit is provided with an adjustment channel, which corresponds to the fixed lens group. The position of the optical lens in the at least one fixed lens group can be corrected through the adjustment channel. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above and other objects, features, and advantages of the present invention will become more apparent through a more detailed description of the embodiments of the present invention in conjunction with the accompanying drawings. The accompanying drawings are provided to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and are not intended to limit the present invention. In the drawings, the same reference numerals generally represent the same components or steps.

[0025] FIG1 is a schematic diagram of the overall structure of the projection module in this application;

[0026] FIG2 is a schematic structural diagram of a projection unit of a projection module in this application;

[0027] FIG3 is a cross-sectional schematic diagram of the projection module in this application;

[0028] FIG4 is an exploded schematic diagram of the projection module in this application;

[0029] FIG5 is a schematic structural diagram of an optical unit in a projection module in the present application;

[0030] FIG6 is a schematic structural diagram of another embodiment of an optical unit in a projection module in the present application;

[0031] FIG7 is a schematic diagram of a partial structure of a projection module provided with an adjustment channel in the present application;

[0032] FIG8 is a schematic structural diagram of an adjustment unit in a projection module in the present application;

[0033] FIG9 is a schematic diagram of the lens barrel structure provided with a through hole in the present application;

[0034] FIG10 is a side sectional view of the adjustment unit provided with an optical lens in the present application. DETAILED DESCRIPTION

[0035] The present invention will be further described below in conjunction with specific implementation methods. It should be noted that, under the premise of no conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0036] In the description of the present invention, it should be noted that, for directional words, such as the terms "center", "horizontal", "longitudinal", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like, indicating directions and positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and cannot be understood as limiting the specific scope of protection of the present invention.

[0037] It should be noted that the terms "first", "second", etc. in the description and claims of this application are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence.

[0038] The terms "comprises" and "having" and any variations thereof in the specification and claims of this application are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus that includes a series of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, product or apparatus.

[0039] In the description of the present invention, it should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct, contact, or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0040] As shown in Figures 1 to 9, the present application provides a projection module, which includes an adjustment unit 10, an optical unit 20 and a projection unit 30. The projection unit 30 is arranged at the rear side of the optical unit 20. The optical signal projected by the projection unit 30 passes through the optical unit 20 to form an image acceptable to the human eye. Among them, the optical unit 20 is arranged in the adjustment unit 10. The optical unit 20 includes at least one optical lens 211 and a polarizing element 212. The polarizing element 212 can be integrated into the optical lens 211 or can be set separately from the optical lens 211. The adjustment unit 10 can adjust the gap between the lenses of the optical lens 211 to extend the optical path of the light projected by the projection unit 30, thereby achieving a larger exit pupil diameter and obtaining clearer imaging with a smaller focal length, thereby reducing the height of the projection module. Furthermore, the polarization element 212 can be implemented as a variety of different types of polarizers, which are correspondingly coordinated with the light signal projected by the projection unit 30, so that the projected light signal passes through the projection element 212, while extending the light propagation path, shortening the focal length of the overall projection module and reducing the height of the projection module.

[0041] As shown in Figures 2 and 3, in a specific embodiment, the projection unit 30 provided in this application includes a screen bracket 311 and a display screen 312. The screen bracket 311 provides corresponding support for the display screen 312. Furthermore, the screen bracket 311 has a first light hole 231 and a screen support base 322. The first light hole 321 is provided in the middle of the screen support base 322. The shape of the projection support base 322 is consistent with that of the display screen 312. The display screen 312 can be directly placed inside the screen support base 322 to reduce the height of the projection unit 30 formed by the combination of the screen bracket 311 and the display screen 312.

[0042] In a specific embodiment, the display screen 312 provided in this application can be a combined package structure. Furthermore, the display screen 312 includes a light-emitting chip 323, a substrate 324, and an encapsulation layer 325. The light-emitting chip 323 array is arranged on the substrate 324. In this embodiment, the light-emitting chip 323 is preferably a mini LED chip or a MicroLED chip. LED as a light source can save energy. The encapsulation layer 325 is used to encapsulate the light-emitting chip 323 on the substrate 324. In some embodiments, the encapsulation layer 325 is formed by applying encapsulation glue to the surface of the Mini LED light board and drying it. The encapsulation layer 325 can include a transparent light-curing or heat-curing resin. The encapsulation layer 325 can also be implemented as a transparent protective glue.

[0043] Furthermore, the display screen 312 may also include a lens array. Specifically, the lens array may include a plurality of super lenses arranged on the surface of the encapsulation layer 325 away from the substrate 324, and each super lens may include a plurality of columnar microstructures. In this embodiment, each super lens monomer corresponds to a separate light-emitting chip 323, thereby achieving diffraction and amplification of the light emitted by the light-emitting chip 323. The super lens array is implemented as a columnar microstructure, wherein the columnar microstructure is perpendicular to the upper surface of the encapsulation layer 325, and each columnar microstructure can be cylindrical or prismatic, that is, the orthographic projection of each columnar microstructure on the first surface can have a circular, rectangular or polygonal shape. Furthermore, the lens array is implemented as a super lens, which can realize the emission of parallel light and can also reduce the angle of light emission. The use of a super lens array for light diffraction can uniformly equalize the brightness of the projected light, thereby improving the light utilization rate of the light-emitting chip 323.

[0044] As shown in Figures 3 and 5, further, the projection module in the present application includes an optical unit 20, which is arranged at the front end of the projection unit 30 and is mainly used to receive the light emitted by the projection unit 30. The light emitted by the projection unit 30 can be received by the human eye through the action of the optical unit 20, thereby obtaining the light information emitted by the projection unit 30. The optical unit 20 includes at least one optical lens 211 and a projection element 212. The optical lens 211 is mainly used to pass the light emitted by the projection unit 30. The projection unit 212 can change the propagation path of the light emitted by the projection unit 30 or extend and / or shorten the propagation path of the light to shorten the imaging distance of the optical system, thereby reducing the length of the optical system and realizing the miniaturization of the overall structure of the projection module.

[0045] As shown in Figure 5, in a specific embodiment, the optical lens includes a first optical lens 221, a second optical lens 222, and a third optical lens 223. The gap between the first optical lens 221 and the second optical lens 222 is adjustable, and the gap between the second optical lens 222 and the third optical lens 223 is also adjustable accordingly. The first optical lens 221 has a first surface 2311 and a second surface 2312, wherein the side close to the projection unit 30 is the second surface 2313, and the side away from the projection unit 30 is the first surface 2311. The first surface 2311 and the second surface 2312 are integrated into the same lens. Furthermore, the surface shape of the first surface 2311 and the second surface 2312 can be selected according to actual needs. Specifically, the first surface 2311 and the second surface 2312 of the first optical lens 221 can be spherical, aspherical, flat, or other irregular surface shapes. The specific surface shape can be selected according to the requirements of the imaging optical system.

[0046] Furthermore, in the present application, the optical lens 211 further includes a second optical lens 222 and a third optical lens 223. The second optical lens 222 has a third surface 2313 and a fourth surface 2314, wherein the side close to the projection unit 30 is the fourth surface 2314, and the side away from the projection unit 30 is the third surface 2313. The third optical lens 223 has a fifth surface 2315 and a sixth surface 2316, wherein the side close to the projection unit 30 is the fifth surface 2315, and the side away from the projection unit 30 is the sixth surface 2316. The surface shapes of the third surface 2312 and the fourth surface 2314 of the second optical lens 222, and the fifth surface 2315 and the sixth surface 2316 of the third optical lens 223 can be selected accordingly according to the imaging requirements of the actual optical system.

[0047] As shown in Figure 5, in a specific embodiment, the polarizing element 212 of the optical unit 20 is integrated on the optical lens 21, wherein the polarizing element 212 includes a semi-reflective semi-transparent film 224, a quarter wave plate 225, a polarizing beam splitter 226 and a polarizer 227. In this embodiment, the semi-reflective semi-transparent film layer is generally configured with TiO2, NBOSE and SiO2 stacking. Due to the use of TiO2, NBOSE and SiO2 materials, the semi-reflective semi-transparent film 224 has a visible light reflectivity of not less than 25% and not more than 75%. Specifically, the semi-reflective semi-transparent film 224 can be arranged on the sixth surface 2316 of the third optical lens 223. In order to ensure the fit between the third optical lens 223 and the semi-reflective semi-transparent film 224, the semi-reflective semi-transparent film 224 can be directly plated on the sixth surface 2316 of the third optical lens 223 using a coating process.

[0048] Furthermore, the quarter-wave plate 225, the polarizing beam splitter 226, and the polarizer are positioned between the first optical lens 221 and the second optical lens 222. To further reduce the overall length of the optical system, a layered coating method can be employed, with the quarter-wave plate first positioned on the second surface 2312 of the first optical lens 221, such that the quarter-wave plate 225 is positioned between the second surface 2312 and the third surface 2313. The quarter-wave plate 225 is a birefringent single-crystal wave plate of a predetermined thickness. When light passes through the wave plate at normal incidence, the phase difference between the ordinary light (o light) and the extraordinary light (e light) is equal to π / 2 or an odd multiple thereof. Such a crystal is called a quarter-wave plate or quarter-wave plate. When linearly polarized light is incident perpendicularly on the quarter-wave plate, and the polarization of the light forms an angle θ with the optical axis of the wave plate (perpendicular to the natural cleavage plane), the light emerges as elliptically polarized light. In particular, when θ = 45°, the emergent light is circularly polarized. The fast and slow axes of a wave plate depend on the type of crystal. For negative crystals, Ve > Vo, and the optical axis of the wave plate is parallel to the wave plate plane. For a quarter-wave plate made from a negative crystal, the optical axis is the fast axis. For a positive crystal, the fast axis is perpendicular to the optical axis and lies within the wave plate plane.

[0049] The polarizing beam splitter 226 splits the incident light according to the corresponding polarization state of the light, with a certain percentage of reflected and transmitted light. The main function of the polarizing beam splitter is to convert the light passing through the polarizing beam splitter into certain polarizations, and the polarizing beam splitter selectively transmits certain polarizations. The polarizing beam splitter 226 is arranged on the surface of the 1 / 4 wave plate and is fixed to the first surface 2311 of the first optical lens 221. The polarizing element 212 can form a light refraction layer, which is fixed to the first surface 2311 of the first optical lens 221. Near the first surface 2311 of the first optical lens 221 are the 1 / 4 wave plate 225, the polarizing beam splitter 226, and the polarizing beam splitter 227. In another feasible embodiment, the light refraction layer can be fixedly set on the third surface 2313 of the second optical lens 222. In order to make the coating between the second optical lens 222 and the light refraction layer more stable, the third surface 2313 of the second optical lens 222 can be set to be planar.

[0050] In the specific imaging process, the light projected by the projection unit 30 is itself left-handed polarized light. After the projected light passes through the semi-reflective semi-transparent membrane 224, 50% of the left-handed polarized light passes through the 1 / 4 wave plate 225, and the left-handed polarized light is processed into parallel polarized light at +45° to the fast axis of the 1 / 4 wave plate (parallel here means parallel to the optical axis). This polarization direction is parallel to the reflection axis of the polarization beam splitter 226. After being reflected by the polarization beam splitter 226, the reflected light is at -45° to the fast axis of the 1 / 4 wave plate 225. The parallel polarized light is converted into left-handed polarized light. After the left-handed polarized light reaches the semi-reflective semi-transparent membrane 224 again, 50% of the projected light is reflected (the energy of the projected light becomes 25% of the original). Since the direction of the optical axis is opposite, the projected light is reflected again into right-handed polarized light, and the right-handed polarized light is converted into linearly polarized light after passing through the 1 / 4 wave plate. The angle between the polarization direction of the light and the fast axis of the wave plate is -45° (the fast axis is 45° counterclockwise). At this time, the polarization direction of the light is consistent with the transmission direction of the polarization beam splitter 226 and the direction of the transmission axis of the polarizer 227. In this solution, the gap between each polarization element is increased, thereby increasing the optical path of the light. The optical unit 20 in the present application uses the polarization element 212 to extend the optical path of the light projected by the projection unit 30. While meeting the imaging requirements of the optical system, the actual size of the optical unit 20 can be shortened and the height of the projection module can be reduced.

[0051] Referring to Figures 5 and 6, Figure 6 illustrates another possible embodiment of the optical unit 10 of the present application. Specifically, the optical unit 10 includes a first optical lens 221, a second optical lens 222, and a third optical lens 223. Furthermore, the optical unit 10 further includes a polarizing element 212. The polarizing element 212 comprises a plurality of polarizers, which, in descending order of distance from the projection unit 30, include: a polarizer 227, a polarizing beam splitter 226, a quarter-wave plate 225, and a transflective membrane 224. The transflective membrane 224 may be integrated with the third optical lens 223. Specifically, the transflective membrane 224 is disposed on a side of the third optical lens 223 proximal to the projection unit 30, i.e., on a sixth surface 2316 of the third optical lens 223. Furthermore, to extend the optical path of the projection light, some components of the polarizing element 212 may be disposed between the first optical lens 221 and the second optical lens 222. Furthermore, a polarizer 227, a polarizing beam splitter 226, and a quarter-wave plate 225 are disposed between the first optical lens 221 and the second optical lens 222. To facilitate the transmission of the projected light, the polarizing element 212 needs to be disposed in a certain order. Specifically, the polarizer 227 is disposed on the second surface 2312 of the first optical lens 221, and the polarizing beam splitter 226 is disposed on the surface of the polarizer 227. The quarter-wave plate can be disposed separately between the first optical lens 221 and the second optical lens 222, or integrated on the third surface 2313 of the second optical lens 222. In order to enhance the stability of the connection between the quarter-wave plate 225 and the second optical lens 222, the quarter-wave plate can be directly fixed to the surface of the second optical lens 222 by coating. Furthermore, during the actual manufacturing process, the polarizer 227, the polarizing beam splitter 226, and the quarter-wave plate 225 are sensitive to assembly precision. For example, the polarizing beam splitter 226 and the quarter-wave plate 225 must be attached based on the phase angle relationship between the absorption axis and the transmission axis. If the polarizing beam splitter 226 and the quarter-wave plate 225 are tilted relative to a preset angle, it is likely to cause deviations in light reflection, transmission, or processing. Generally speaking, in the prior art, the polarizing beam splitter 226 and the quarter-wave plate 225 have an absorption axis angle tolerance of 2-3°. In the prior art, the three film materials, namely the polarizer 227, the polarization splitter 226 and the 1 / 4 wave plate 225, need to be attached together. Errors will accumulate between each layer of the film, which may eventually cause the polarizer 227, the polarization splitter 226 and the 1 / 4 wave plate 225 to have an overall angle error greater than 3°, thereby affecting light processing and affecting the projected image.In addition, during the attachment process in the film attaching equipment, the large film material is positioned solely by mechanical positioning. As described in the previous process, there will be a problem of error accumulation after multiple film materials are superimposed, which will affect the phase deviation of the absorption axis or transmission axis of the film material, and ultimately lead to error accumulation in the projected light.

[0052] In order to solve the above problems, in this application, the surface of the first optical lens 221 close to the projection unit 30 is set to a plane, and the surface of the first optical lens away from the projection unit 30 is set to a convex surface, thereby reducing the aberration of the projected image, improving the image quality of the projected image, and shortening the size of the optical machine module. Furthermore, in this embodiment, the polarizer 227 and the polarization beam splitter 226 are attached together as a whole. The difference is that the 1 / 4 wave plate 225 is first attached flat on a thin flat plate as a component to be assembled. In this embodiment, the semi-reflective and semi-transparent film 224 is an optical coating process, which is vapor deposited on the surface of the third optical lens 223 close to the projected light. Therefore, in this embodiment, the semi-reflective and semi-transparent film 224 does not have the problem of assembly tilt angle. The first optical lens 221 and the second optical lens 222 are set by active calibration. There is an angle of less than 3° between the first optical lens 221 and the second optical lens 222, thereby improving the assembly angle error of the 1 / 4 wave plate 225 assembled on the flat plate, which can make the assembly effect better. Alternatively, the first optical lens 221, the quarter-wave plate 225, and the flat plate are assembled together through active calibration, and an angle of less than 3° exists between the first optical lens 221 and the flat plate, thereby improving the assembly angle error of the quarter-wave plate 225 when assembled to the flat plate, which can achieve a better assembly effect. Alternatively, the second optical lens 222, the quarter-wave plate 225, and the flat plate are assembled together through active calibration, and an angle of less than 3° exists between the second optical lens 222 and the flat plate, thereby improving the assembly angle error of the quarter-wave plate when assembled to the flat plate, which can achieve a better assembly effect.

[0053] In a preferred embodiment, in order to reduce the total optical length of the optical unit 20 and realize the miniaturization of the overall projection module structure, the quarter wave plate 225 is directly integrated on the third surface 2313 of the second optical lens 222, wherein, in order to ensure the installation accuracy of the quarter wave plate 225, the third surface 2313 of the second optical lens 222 can be set to be planar or close to a planar shape. Furthermore, the second surface 2312 of the first optical lens 211 is also set to be correspondingly planar or close to a planar shape, and the polarizing beam splitter 226 and the polarizer 227 are integrated on the second surface 2312 of the first optical lens 211. The planar lenses can make the connection between the polarizing beam splitter 226, the polarizer 227 and the first optical lens 221 more stable. In this application, as long as the relative angles of the polarizer 227, the polarization beam splitter 226, and the quarter-wave plate 225 are relatively corrected, and the relative positions of the three are able to produce a good projection image under the joint action of the optical lens 211, it can be shown that the relative positions of the polarizer 227, the polarization beam splitter 226, and the quarter-wave plate 225 with the optical lens 211 do not affect the projection imaging, and the overall imaging is good. Furthermore, the polarization beam splitter 226 and the polarizer 227 are fixed to the first optical lens 221, and the quarter-wave plate 225 is fixed to the second optical lens 222. The first optical lens 221 and the second optical lens 222 are assembled using an active calibration method, which can achieve a better assembly effect of the folded optical path component, improve the assembly angle error between the folded optical path components, and achieve a higher assembly yield.

[0054] As shown in FIG7 , the optical lens 211 is disposed within the lens barrel 114. A corresponding adjustment channel 129 may be provided on the side of the lens barrel 114. The adjustment channel 129 is primarily used to adjust the position of the optical lens 211. In a specific embodiment, the adjustment channel 129 is provided at a position corresponding to the second optical lens 222. There are at least two adjustment channels 129 symmetrically disposed on the lens barrel 114. During assembly, the tilt or rotation position of the second optical lens 222 can be adjusted via the adjustment channels 129 provided on the lens barrel 114. Specifically, the first optical lens 221 is fixed, and the second optical lens 222 is adjusted through active calibration. Since the polarizing element 212 is integrated with the optical lens 211, the position of the second optical lens 222 and / or the polarizing element 212 can be adjusted by adjusting the position of the optical lens 221. This improves the assembly accuracy of the optical unit 20, resulting in a clearer projected image and a higher assembly yield rate for the projection module.

[0055] In another feasible embodiment, the polarization element 212 and the optical lens 211 are arranged separately, that is, some elements of the polarization element 212 are arranged between the first optical lens 221 and the second optical lens 222, wherein the polarization element 212 arranged between the first optical lens 221 and the second optical lens 222 further includes a 1 / 4 wave plate 225, a polarization splitter 226 and a polarizer 227, and some elements of the polarization element 212 can be directly integrated on the optical lens 221. As in at least one specific embodiment of the present application, the polarization splitter 226 and the polarizer 227 in the polarization element 212 are integrated on the second surface of the first optical lens 221. Furthermore, the quarter-wave plate 225 can be a separate optical element. In one optional embodiment, it is integrated onto a planar transparent substrate. The planar transparent substrate on which the quarter-wave plate is integrated is disposed adjacent to the third surface 2313 of the second optical lens 222, i.e., the surface of the second optical lens 222 away from the projection unit 30. In some optional embodiments, a certain gap exists between the quarter-wave plate and the third surface 2313 of the second optical lens 222. An adjustment channel 129 is provided on the sidewall of the lens barrel 114 corresponding to the side edge of the second optical lens 222. The position of the polarizing element 212 can be adjusted through the adjustment channel 129 reserved on the lens barrel 114. In some optional embodiments, the tilt or rotation position of the quarter-wave plate 225 can be adjusted so that the quarter-wave plate cooperates with other polarizing elements 212 integrated onto the optical lens 221, thereby improving the assembly error of the quarter-wave plate 225 relative to other optical unit components to obtain a clear projected image.

[0056] In another feasible embodiment, an adjustment channel 129 is provided on the side wall of the lens barrel 114 corresponding to the side of the first optical lens 221, and the position of the polarizing element 221 can be adjusted through the adjustment channel 129 reserved on the lens barrel 114. As in at least one specific embodiment of the present application, the polarization splitter 226 and the polarizer 227 in the polarization element 212 are integrated on the second surface of the first optical lens 221, and the relative positions of the first optical lens 221 and / or the polarization splitter 226 and / or the polarizer 227 can be adjusted through the adjustment channel 129 reserved on the lens barrel 114. In some specific embodiments, the tilt or rotation position of the above-mentioned devices is not adjusted, so that the 1 / 4 wave plate cooperates with other polarization elements 212 integrated on the optical lens 221, thereby improving the assembly error of the 1 / 4 wave plate 225 relative to other optical unit devices to obtain a clear projected image.

[0057] As shown in Figures 5 and 6, the present application provides a folded optical path solution for reducing stray light, wherein the end of the optical lens 211 away from the projection unit 30 is the first optical lens 2211, the second optical lens 222 and the third optical lens 223 in sequence, wherein the second optical lens 222 and the third optical lens 223 are connected by gluing to improve the integration of the optical system and shorten the size of the projection module. The first surface 2311 of the first optical lens 221 is convex, and the third surface 2313 of the second optical lens 222 is concave, and the curvature is roughly the same, thereby reducing the aberration of the projected image, improving the image quality of the projected image, and shortening the size of the lens module. The fourth surface 2314 of the second optical lens 222 is a plane, and the third surface 2313 of the second optical lens is concave, which can also reduce the aberration of the projected image accordingly. The sixth surface 2316 of the third optical lens 223 is convex, and the fifth surface 2315 of the third optical lens 223 is convex, thereby reducing aberrations in the projected image, improving image quality, and shortening the height of the projection module. The polarizer 227 and the polarization splitter 226 are sequentially superimposed on the first surface 2311, with the polarizer 227 positioned further away from the projection unit 30. This improves the package integration of the projection module and reduces its size.

[0058] The second optical lens 222 and the third optical lens 223 are bonded together by glue. In this embodiment, the quarter wave plate 225 is attached between the second optical lens 222 and the third optical lens 223. The bonding layer is provided between the quarter wave plate 225 and the fourth surface 2314. Furthermore, the bonding layer is also provided between the quarter wave plate 225 and the fifth surface 2315. The semi-reflective and semi-transparent film 224 is provided on the outside of the sixth surface 2316. In this embodiment, the reflection ratio of the semi-reflective and semi-transparent film 224 can be 40% reflection and 60% projection, or 60% reflection and 40% projection, preferably 50% reflection and 50% projection (the overall light efficiency of the system is the highest), thereby improving the utilization rate of the overall projected light.

[0059] Specifically, the other optical lens surfaces in contact with the air in the optical lens 211 can be coated with a reflective film (AR film), and the reflectivity of the anti-reflective film is less than 0.5%, thereby enhancing the utilization rate of the projected light. In this embodiment, the curvature radius of the second surface 2312 and the third surface 2313 is a spherical or aspherical surface with a negative value, and the curvature radius of the sixth surface 2316 is a spherical or aspherical surface with a negative value, thereby reducing the aberration of the projected image, improving the quality of the projected image, and shortening the size of the projection module. In this embodiment, the material of the first optical lens 221 and the third optical lens 223 is a high refractive index material with a refractive index of 1.7-1.8, wherein the second optical lens 222 is a low refractive index material with a refractive index of 1.60-1.65, thereby optimizing the optical design of the module and shortening the size of the lens projection module.

[0060] The present application also provides another feasible folded optical path solution for reducing stray light, wherein the end of the optical lens 211 away from the projection unit 30 is the first optical lens 221, the second optical lens 222 and the third optical lens 223, wherein the first optical lens 221 and the second optical lens 222 are fixedly connected by gluing. Furthermore, the gap between the first optical lens 221 and the second optical lens 222 is smaller than the gap between the second optical lens 222 and the third optical lens 223, and the distance between the second optical lens 222 and the first optical lens 221 remains fixed. The distance between the second optical lens 222 and the third optical lens 223 can be adjusted accordingly, and the specific adjustment device will be described in detail in conjunction with the projection module later.

[0061] Specifically, the second surface 2312 of the first optical lens 221 is planar, and the third surface 2213 of the adjacent second optical lens 222 is also planar. The optical unit 20 further includes a polarizing element 212 that extends the optical path, wherein a portion of the refractive component is disposed between the first optical lens 221 and the second optical lens 222. To further reduce the space occupied by the refractive component, the refractive component can be directly integrated onto the second surface 2312 and / or the third surface 2313 through coating. The quarter-wave plate 225, the polarizing beam splitter 226, and the polarizer 227 of the polarizing element 212 are disposed between the second surface 2212 and the third surface 2213. In an optional embodiment, the quarter-wave plate can be integrated on the second surface 2312, the polarization beam splitter 226 is integrated on the quarter-wave plate 225, and the polarizer 226 is integrated on the polarization beam splitter 227, that is, all of the refractive components are fixed on the second surface 2312. In another optional embodiment, the quarter-wave plate 225 is fixed to the second surface 2312 by coating, and then the polarization beam splitter 226 and the polarizer 227 are fixed to the quarter-wave plate 225 in sequence. Specifically, the quarter-wave plate 225, the polarization beam splitter 226, and the polarizer 227 can be selectively arranged on the second surface 2312 and / or the third surface 2313, as long as the effect of extending the optical path in the solution is achieved.

[0062] Furthermore, in order to facilitate the corresponding coating on the optical lens 211, the surfaces on which the coating is applied on the first optical lens 221, the second optical lens 222, and the third optical lens 223 can be set to be planar. Specifically, the quarter wave plate 225, the polarization beam splitter 226, and the polarizer 227 are fixed to the second surface 2312 and / or the third surface 2313. The corresponding second surface 2312 and the third surface 2313 can be set to be planar to facilitate the coating process. The first surface 2211 of the first optical lens 221 is set to a convex surface, and the fourth surface 2214 of the second optical lens 222 is set to a concave surface, thereby reducing the aberration of the projected image, improving the image quality of the projected image, and shortening the size of the projection module. The fifth surface 2315 and the sixth surface 2316 of the third optical lens 223 can be selectively set to a convex shape to better optimize the optical imaging system. The light projected by the projection unit 30 passes through the third optical lens 223, passes through the second optical lens 222, and is emitted from the first optical lens 221 to be received by the human eye.

[0063] Among them, the semi-reflective and semi-transparent film 224 is arranged on the sixth surface 2316. In this embodiment, the reflection ratio of the semi-reflective and semi-transparent film 224 can reflect 40% and project 60%, or it can reflect 60% and transmit 40%, preferably reflect 50% and project 50% (the overall system light efficiency is the highest), thereby improving the brightness utilization rate of the projected image. The surface of the optical lens 211 on which the refractive device is not provided can be coated with an anti-reflection film (AR film), and the reflectivity of the anti-reflection film is less than 0.5%, thereby enhancing the utilization rate of the projected light. In this embodiment, the second surface 2312 and the third surface 2313 of the optical lens 211 are planar, so that the coating can be performed on the planar lens to extend the optical path of the projected light. The sixth surface 2316 can be set to a convex surface, wherein the curvature radius of the sixth surface 2316 is a spherical surface or an aspherical surface with a negative value, thereby reducing the aberration of the projected image, improving the image quality of the projected image, and shortening the size of the projection module. In this embodiment, the materials of the first optical lens 221 and the third optical lens 223 are high refractive index materials with a refractive index of 1.60-1.65, which can optimize the optical design of the projection module and shorten the size of the projection module.

[0064] As shown in Figures 4 to 10, specifically, the gaps between the lenses of the optical lens 211 in the present application can be adjusted accordingly. In this solution, the distances between the optical lenses are mainly adjusted by the adjustment unit 10. In this embodiment, the optical lens 211 includes the first optical lens 221, the second optical lens 222, and the third optical lens 223. The distance between the first optical lens 221 and the second optical lens 222 remains fixed, and the distance between the second optical lens 222 and the third optical lens 223 can be adjusted accordingly. Furthermore, the adjustment unit 10 includes a pressure cover 111, a rotating ring 112, a gasket 113, and a lens barrel 114. The lens barrel 114 is mainly used to accommodate the optical lens 211. The rotating ring 112 is disposed on the outer side of the lens barrel 114 and can be rotated relative to the lens barrel 114 to adjust the distances between the lenses of the optical lens 211. The gasket 113 is arranged between the rotating ring 112 and the lens barrel 114 to ensure the stability of the connection between the lens barrel 114 and the rotating ring 112. The pressure cover 111 is arranged on the upper end surface where the rotating ring 112 and the lens barrel 114 are combined. While limiting the upward movement of the rotating ring 112, it can prevent external dust from entering the gap between the rotating ring 112 and the lens barrel 114, thereby ensuring the stability of the projection module imaging.

[0065] As shown in FIG10 , in a specific embodiment, the lens barrel 114 is primarily used to accommodate the optical lens 211. To facilitate the passage of projected light, the lens barrel 114 has a second light hole 127. The second light hole 127 is reserved in the center of the lens barrel 114, and the optical lens 211 is accommodated within the second light hole 127 of the lens barrel 114. The light projected by the projection unit 30 passes through the optical lens 211 and is emitted from the second light hole 127 of the lens barrel 114, thereby reaching the human eye or other receiving unit. Furthermore, the lens barrel 114 also has a lens barrel body 128, and the lens barrel body 128 can be divided into an inner side 1216 of the lens barrel and an outer side 1217 of the lens barrel, wherein the inner side 1216 of the lens barrel is mainly used to accommodate the optical lens 211, and the outer side 1217 of the lens barrel is used to set the rotating ring 112. Furthermore, the inner side 1216 of the lens barrel has a plurality of step portions, and the optical lens 211 is fixed on the step portions. The lenses are separated by using the structure of the step portions so that there is an adjustable gap between the lenses.

[0066] In the present application, the optical lens 211 includes a first optical lens 221, a second optical lens 222, and a third optical lens 223. The inner side 1216 of the lens barrel 114 is provided with three steps, which are respectively a first step 12161, a second step 12162, and a third step 12163 along the optical axis. The first step 12161 is provided with the first optical lens 221, the second step 12162 is provided with the second optical lens 222, and the third step 12163 is provided with the third optical lens 223. In order to reduce the head portion of the optical unit 20, the diameter of the first optical lens 221 can be made smaller than the diameter of the second optical lens 222. The corresponding height of the first step portion 12161 is smaller than the height of the second step portion 12162, so that the first optical lens 221 can be set at the exit position of the lens barrel 114, and the distance between the second optical lens 222 and the third optical lens 223 can be adjusted accordingly, so the distance between the second step portion 12162 and the third step portion 12163 is greater than the distance between the second step portion 12162 and the first step portion 12161.

[0067] As shown in FIG9 , specifically, in one optional embodiment, the outer side 1217 of the lens barrel is composed of a first circular ring 12171 and a second circular ring 12172. The diameter of the first circular ring 12171 is smaller than the diameter of the second circular ring 12172, and the first circular ring 12171 and the second circular ring 12172 are integrally formed. A rotating ring 112 and a pressure cover 111 are provided on the outer side 1217 of the lens barrel. In order to better fix the pressure cover 111 to the outer side 12172 of the lens barrel, a corresponding snap-fit ​​member 12173 is further provided on the first circular ring 12171 of the outer side 1217 of the lens barrel for fixing to the pressure cover 111. The first circular ring 12171 and the second circular ring 12172 have different diameters, and a horizontal circular ring 12174 is formed at the connection between the first circular ring 12171 and the second circular ring 12172. The horizontal circular ring 12174 can provide corresponding support for the rotating ring 112. The outer side 1217 of the lens barrel also has a second circular ring 12172. In order to better position the rotating ring 112 on the second circular ring 12172, the second circular ring 12172 is correspondingly provided with the first circular groove 12173 and the second circular groove 12174. The first circular groove 12173 and the second circular groove 12174 are arranged parallel to each other on the second circular ring 12172, and there is a certain distance between them.

[0068] In order to adjust the position of the third optical lens 223 in the lens barrel, the second circular ring 12172 on the outer side 1217 of the lens barrel has a plurality of through holes 12175, which extend from the inner side 1216 of the lens barrel to the outer side 1217 of the lens barrel. The number of through holes 12175 can be multiple. In a specific embodiment, the number of through holes 12175 is three, which are evenly spaced on the outer side of the second circular ring 12172. The through holes 12175 have a certain inclination angle with the bottom of the lens barrel 114, and the inclination angle is no greater than 45 degrees. Furthermore, the orthographic projection of the through holes 12175 on the bottom surface of the lens barrel 114 is consistent with the bottom edge of the lens barrel 114. The third optical lens 223 may be provided with a corresponding fastener, such as a screw, which is fixed to the side of the third optical lens 223. One side of the fastener is fixed to the third optical lens 223, and the other side is a free end. The free end can extend a certain length along the through hole 12175 on the outer side 1217 of the lens barrel. There may be multiple fasteners. In a specific embodiment, the number of fasteners is consistent with the number of through holes 12175. The fasteners are evenly arranged along the edge of the third optical lens 223, and one side of the fastener extends into the through hole 12175 to contact the rotating ring 112.

[0069] As shown in Figures 8, 9, and 10, the rotating ring 112 is further disposed on the outside of the lens barrel 114. The rotating ring 112 has a third light hole 123 and a circular ring body 124. The third light hole 123 on the rotating ring 112 is aligned with the center of the second light hole 127 on the lens barrel 114 to ensure the passage of the projected light. In a specific embodiment, the rotating ring 112 is disposed on the outer side of the lens barrel 114. To ensure a stable connection between the rotating ring 112 and the lens barrel 114, a corresponding gasket 113 is disposed between the rotating ring 112 and the lens barrel 114. The gasket 113 can be made of rubber material. Specifically, the gasket 113 includes a first sealing ring 125 and a second sealing ring 126. The first sealing ring 125 is arranged in the first circular groove 12173, and the second sealing ring 126 is arranged in the second circular groove 12174. Through the intermediary effect of the first sealing ring 125 and the second sealing ring 126, the rotating ring 112 and the lens barrel 114 can be better fixed.

[0070] As shown in FIG8 , specifically, the circular ring body 124 on the rotating ring 112 can be divided into a circular ring inner side 1214 and a circular ring outer side 1215. The circular ring inner side 1214 has a horizontal boss 12141 and a vertical groove 12142. The horizontal boss 12141 is supported on the horizontal circular ring 12174 on the lens barrel outer side 1217, so that the rotating ring 112 and the golden child 114 are supported by the horizontal circular ring 12174. Furthermore, a plurality of vertical grooves 12142 are provided on the circular ring inner side 1214. The positions of the vertical grooves 12142 correspond to the positions of the through holes 12175 provided on the lens barrel 114. The vertical grooves 12142 have a certain height, and the number of the vertical grooves 12142 is consistent with the number of the through holes 12175. One side of the fastener on the third optical lens 223 is fixedly connected to the third optical lens 223 , and the other side of the fastener passes through the through hole 12175 on the outer side 1217 of the lens barrel and extends into the vertical groove 12142 .

[0071] In the present application, the vertical groove 12142 on the inner side 1214 of the rotating ring 112 can be adjusted so that the vertical groove 12142, which is confined on the inner side 1414 of the rotating ring, drives the fastener to move along the direction of the through hole 12175 on the lens barrel 114 by adjusting the position of the rotating ring 112. Furthermore, the through hole 12175 on the lens barrel 114 has a predetermined direction, and the direction of the vertical groove 12142 on the inner side 1214 of the rotating ring 112 is consistent with the direction of the optical axis. When the rotating ring 112 moves along the direction of the optical axis, the vertical groove 12142 provided thereon can drive the third optical lens 223 to move along the direction of the optical axis, thereby adjusting the gap between the third optical lens 223 and the optical lens 222, thereby changing the optical system parameters of the projection module to meet different imaging requirements. Furthermore, to facilitate adjustment of the rotating ring 112, a corresponding thread strip 12151 is provided on the outer side 1215 of the ring body 124. The thread strip 1151 is primarily used to increase the friction of the rotating ring 112, thereby facilitating a better grip of the rotating ring 112. The thread strip 12151 on the outer side 1215 of the ring can be configured as a horizontal thread or a vertical thread, which is not limited here.

[0072] In a specific embodiment, a corresponding pressure cap 111 is provided at the top position where the rotating ring 112 contacts the lens barrel 114. The pressure cap 111 can be used to limit the movement of the rotating ring 112. The pressure cap 111 has a fourth light hole 121. The fourth light hole 141 is aligned with the center of the third light hole 123 on the rotating ring 112. The projection light can be emitted through the fourth light hole 121 on the pressure cap 111. The pressure cap 111 also has a pressure cap ring 122. The pressure cap ring 122 is mainly fixed to the top position of the lens barrel 114. The top position of the lens barrel 114 is provided with a corresponding latch 12173. The corresponding pressure cap ring 122 is provided with a latch groove 1313. The pressure cap ring 122 is fixed to the lens barrel 114 through the latch groove 1313 thereon to prevent the rotating ring 112 from being separated from the lens barrel 114.

[0073] Furthermore, the gland ring 122 further includes a first gland ring 1311 and a second gland ring 1312. The first gland ring 1311 and the second gland ring 1313 can be integrally formed. The diameter of the first gland ring 1311 is smaller than the diameter of the second gland ring 1312, wherein the first gland ring 1311 covers the surface of the first optical lens 221. By covering the surface of the first optical lens 221 with the first gland ring 1311, light can be prevented from leaking from the side of the first optical lens 221, thereby preventing stray light from being generated during the imaging process. The second gland ring 1312 is disposed on the side of the first optical lens 221, wherein the lower end surface of the second gland ring 1312 rests on the horizontal boss 12141 of the rotating ring 112. While closing the gap between the rotating ring 112 and the lens barrel 114, the volume of the gland 111 can be further reduced, thereby miniaturizing the entire projection module.

[0074] The projection module provided in the present application can be applied to a virtual device, specifically to a head-mounted virtual device. In order to improve the user's use effect, the number of the projection modules in the virtual device can be two, and the two projection modules can be set adjacent to each other, and the distance between them is consistent with the distance between human eyes. Correspondingly, in order to improve the imaging quality of the virtual device, the gap between the two projection modules in the virtual device can be adjusted accordingly according to the distance between the user's eyes to improve the user's experience effect. Referring to Figure 1, during the imaging process of the projection module, the projection light emitted by the projection module 30, after the propagation of the optical unit 20 and the action of the adjustment unit 10, can be emitted from the front end of the optical lens 211, so that the human eye can receive the light signal emitted by the projection unit 30, that is, the human eye can receive the image information transmitted by the projection unit 30, thereby improving the image quality, allowing the user to have an immersive feeling, and further enhancing the authenticity of the imaging.

[0075] The above describes the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the foregoing embodiments. The foregoing embodiments and description merely illustrate the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed by the present invention is defined by the appended claims and their equivalents.

Claims

1. A projection module comprising a projection unit, an adjustment unit, and an optical unit, wherein the projection light emitted by the projection unit can be emitted through the optical unit, and the optical unit is disposed inside the adjustment unit; The optical unit further includes at least one optical lens and at least one polarizing element, wherein the polarizing element is mainly used to change the propagation path of the projection light, and the polarizing element is arranged between the optical lenses; There are multiple optical lenses, including a first optical lens, a second optical lens, and a third optical lens, wherein the first optical lens and the second optical lens constitute a fixed lens group and are fixedly disposed on the adjustment unit, and the third optical lens is movably disposed on the adjustment unit for focusing, the surface of the first optical lens facing the projection unit is planar, and some elements of the polarization element are disposed between the first optical lens and the second optical lens; characterized in that: The adjustment unit is provided with an adjustment channel, which corresponds to the fixed lens group. The position of the optical lens in the at least one fixed lens group can be corrected through the adjustment channel.

2. The projection module according to claim 1, wherein: The polarization element includes a semi-reflective and semi-transparent film, a 1 / 4 wave plate, a polarization splitter and a polarizer. The polarization element can be integrated on the optical lens by coating, wherein the semi-reflective and semi-transparent film is integrated on the third optical lens.

3. The projection module according to claim 2, wherein: The polarization element is a semi-reflective and semi-transparent film, a 1 / 4 wave plate, a polarizer and a polarization splitter in sequence along the direction of the optical axis, wherein the 1 / 4 wave plate, the polarizer and the polarization splitter are arranged between the first optical lens and the second optical lens.

4. The projection module according to claim 3, wherein: The 1 / 4 wave plate is arranged on a planar object, and the planar object is arranged between the first optical lens and the second optical lens, wherein the 1 / 4 wave plate is fixed on the planar object by coating.

5. The projection module according to claim 2, wherein: The polarizer and the polarizing beam splitter are superimposed on the first optical lens in order, and the polarizer is located at a position farther away from the end of the projected light, wherein the polarizing beam splitter is in contact with the surface of the first optical lens, and the polarizer is arranged on the polarizing beam splitter.

6. The projection module according to any one of claims 1 to 5, characterized in that: The materials of the first optical lens and the third optical lens are high refractive index materials, and the second optical lens is low refractive index material.

7. The projection module according to claim 6, wherein: The distance between the optical lenses is adjustable, wherein the distance between the first optical lens and the second optical lens remains unchanged, and the distance between the second optical lens and the third optical lens is adjustable.

8. The projection module according to claim 6, wherein: The distance between the optical lenses is adjustable, wherein the second optical lens is glued together with the third optical lens, and the position of the first optical lens is adjustable.

9. The projection module according to claim 7, wherein: The gap between the first optical lens and the second optical lens is smaller than the gap between the second optical lens and the third optical lens.

10. The projection module according to claim 9, wherein: One end of the first optical lens close to the projection unit is a first surface, and the lens surface of the first surface is a plane.

11. The projection module according to claim 10, wherein: The second optical lens is glued to the third optical lens, and the 1 / 4 wave plate is arranged between the second optical lens and the third optical lens, wherein the first optical lens and the second optical lens can be fixed by active calibration.

Images