Projection lens module and projection device

Abstract

Embodiments of the present application provide a projection lens module and a projection device; the projection lens module comprises a first lens group, a diaphragm and a second lens group arranged along an optical axis; the first lens group comprises a first lens, a second lens, a third lens, a fourth lens and a double cemented lens arranged in sequence, the first lens, the second lens and the third lens are negative focal power, and the fourth lens and the double cemented lens are positive focal power; the second lens group comprises a triple cemented lens and a tenth lens, the triple cemented lens is negative focal power, and the tenth lens is positive focal power; the diaphragm is located between the double cemented lens and the triple cemented lens, the interval between the diaphragm and the double cemented lens is L1, and the interval between the diaphragm and the triple cemented lens is L2, L1 and L2 satisfy 3.3 < L1 / L2 < 4; the first lens is a plastic aspherical lens, and the tenth lens is a glass aspherical lens.

Description

Technical Field

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

[0002] Currently, projection devices are increasingly widely used in home entertainment, office presentations, and other scenarios. Traditional projectors typically use long-focal-length or standard-focal-length projection lenses. These lenses require a relatively large projection distance and have strict requirements for the installation location, for example: Large space requirement: conventional projectors, see Figure 1 It needs to be placed at a distance from the projection wall (usually more than 2 meters), which reduces the space utilization of the living room or meeting room, and its use is limited, especially in small apartment environments.

[0003] Obstruction issue: Due to the limitations of the projection angle, there should be no obstructions (such as furniture, decorations, etc.) between the projector and the projection wall, otherwise it will affect the integrity of the projected image and the user experience.

[0004] The optical design is complex: Existing short-throw projection lenses usually use reflective structures (such as freeform mirrors or reflector bowls) to shorten the projection distance, but this design not only increases the size and weight of the system, but also increases the manufacturing cost and assembly difficulty.

[0005] To address the aforementioned issues, some existing technologies have attempted to employ refractive short-throw projection lens designs; however, these technologies still suffer from the following shortcomings: (1) It is difficult to balance the throw ratio (TR) and offset: In the design of short-throw lenses, reducing the throw ratio (TR) usually leads to a decrease in offset, making the projected image closer to the projector body and more easily blocked by the body.

[0006] (2) Limited optical performance: When existing short focal length lenses achieve a small projection ratio (such as TR≤0.6), they often need to increase the number of lenses (such as more than 12 lenses) or adopt many complex aspherical designs, which leads to increased system costs and makes it difficult to correct aberrations (such as distortion, chromatic aberration, etc.).

[0007] (3) Difficulty in balancing size and image quality: Although some short focal length lenses are small in size, their image plane uniformity is poor, and the MTF (modulation transfer function) of the edge field of view drops significantly, affecting the display effect.

[0008] Therefore, there is an urgent need for a new type of projection lens module that can reduce the number of lenses, reduce system complexity, and have excellent optical performance while ensuring a small throw ratio and a large offset. Summary of the Invention

[0009] The purpose of this application is to provide a new technical solution for a projection lens module and a projection device.

[0010] In a first aspect, embodiments of this application provide a projection lens module, the projection lens module comprising components arranged along the same optical axis: The first lens group includes a first lens, a second lens, a third lens, a fourth lens, and a cemented doublet lens arranged sequentially along the optical axis, wherein the first lens, the second lens, and the third lens are all negative optical power, and the fourth lens and the cemented doublet lens are both positive optical power; The second lens group includes a cemented triplet lens and a tenth lens arranged along the optical axis, wherein the cemented triplet lens has negative optical power and the tenth lens has positive optical power; An aperture stop is located between the cemented doublet lens and the cemented triplet lens. The distance between the aperture stop and the cemented doublet lens is L1, and the distance between the aperture stop and the cemented triplet lens is L2. Furthermore, L1 and L2 satisfy the following condition: 3.3 <L1 / L2<4; The first lens is a plastic aspherical lens, and the tenth lens is a glass aspherical lens.

[0011] Optionally, the center thickness T' of the triplex lens satisfies 8.5%≤T' / TTL≤10%; where TTL is the total optical length of the projection lens module.

[0012] Optionally, the cemented lens is composed of a seventh lens, an eighth lens, and a ninth lens cemented together sequentially, wherein: Both the seventh lens and the ninth lens are positive optical power; The eighth lens has a negative optical power; The refractive index of either the seventh lens or the ninth lens is lower than that of the eighth lens.

[0013] Optionally, the cemented doublet lens is composed of a fifth lens and a sixth lens cemented together, wherein: The fifth lens and the sixth lens have opposite optical powers. One of the fifth lens and the sixth lens has a positive optical power and the other has a negative optical power. The refractive index of the lens with positive optical power is higher than that of the lens with negative optical power.

[0014] Optionally, the fifth lens has a positive optical power and a refractive index of N5, and the sixth lens has a negative optical power and a refractive index of N6, wherein N5 and N6 satisfy the following relationship: 1.03. <N5 / N6<1.1。

[0015] Optionally, the first lens group satisfies: 0.95<T3 / (T1+T2)<1.3, wherein: T1 is a central thickness of the first lens, T2 is a central thickness of the second lens, and T3 is a central thickness of the third lens.

[0016] Optionally, the central thickness T1 of the first lens satisfies 3.3%≤T1 / TTL≤3.7%; the central thickness T2 of the second lens satisfies 1.5%≤T2 / TTL≤1.8%; wherein TTL is a total optical length of the projection lens module.

[0017] Optionally, a sag of a surface of the second lens away from the diaphragm at the maximum aperture is S1, and a sag of a surface of the second lens close to the diaphragm at the maximum aperture is S2, which satisfies: 3.5<S2 / S1<4.5.

[0018] Optionally, an included angle between a tangent line of a surface of the second lens away from the diaphragm at the maximum aperture and an optical axis is A1, and an included angle between a tangent line of a surface of the second lens close to the diaphragm at the maximum aperture and the optical axis is A2, which satisfies: 40°<A1-A2<50°, and 1.8<A1 / A2<2.3.

[0019] Optionally, an included angle between a tangent line of a surface of the third lens away from the diaphragm at the maximum aperture and the optical axis is A3, and an included angle between a tangent line of a surface of the third lens close to the diaphragm at the maximum aperture and the optical axis is A4, which satisfies: 40°<A3-A4<60°, and 1.6<A3 / A4<2.1.

[0020] Optionally, the projection lens module further comprises a prism, a glass flat plate and a display unit which are sequentially arranged on a side of the tenth lens away from the diaphragm; a ratio of the total optical length TTL of the projection lens module to a maximum aperture D1 of the lenses in the projection lens satisfies: 1.5<TTL / D1<1.9.

[0021] Optionally, effective focal lengths of the respective lenses in the projection lens are respectively: an effective focal length of the first lens is F1, -32mm≤F1≤-24mm; an effective focal length of the second lens is F2, -19mm≤F2≤-14mm; an effective focal length of the third lens is F3, -19mm≤F3≤-14mm; an effective focal length of the fourth lens is F4, 25mm≤F4≤36mm; an effective focal length of the cemented doublet is F', 17mm≤F'≤25mm; The effective focal length of the triplet lens is F'', where -80mm ≤ F'' ≤ -55mm; The effective focal length of the tenth lens is F10, where 9mm ≤ F10 ≤ 14mm; The second lens to the ninth lens are glass spherical lenses.

[0022] Optionally, the projection lens module has a focal length of 2.83mm, a throw ratio TR of 0.5, a relative aperture of 1 / 1.699, an Offset of 140%, a pixel size of 5.4μm, a field of view of 55°~59°, an image surface size of 8.5mm~9.1mm, and an operating wavelength band of 455nm~630nm.

[0023] In a second aspect, embodiments of the present application provide a projection device, the projection device comprising: a housing; and the projection lens module according to the second aspect.

[0024] The beneficial effects of the present application are: The projection lens module provided by the embodiments of the present application adopts a specially designed lens combination: the first lens group adopts a "negative-negative-negative-positive-cemented doublet (positive)" structure, and the second lens group adopts a "triplet cemented (negative)-positive" structure. This power distribution achieves reasonable light refraction and focusing, and effectively improves imaging quality. Among them, the design of three negative lenses in the first lens group not only simplifies the optical path structure, but also effectively corrects field curvature and distortion, and improves the flatness of the image. The triplet cemented lens in the second lens group compensates for axial chromatic aberration through its complex refraction characteristics, further improving color reproduction and imaging clarity. Benefiting from the optimized power distribution above, the projection lens module of the present application can maintain excellent imaging quality within the full field of view (55°~59°). Especially for the common distortion problem of short-throw projection systems, the present application effectively controls distortion to a low level (e.g., within 1.5%), which is significantly better than similar products.

[0025] The present application adopts a compact optical architecture, and by reasonably arranging the positions of each lens and setting the stop (which is located between the cemented doublet and the triplet cemented lens and satisfies the spacing ratio relationship of 3.3 < L1 / L2 < 4), effectively shortens the total optical length. The total optical length of the entire projection lens module can be controlled within 78mm for example, and the maximum caliber does not exceed 47mm, which greatly reduces the volume and weight. This compact design not only reduces production costs, but also makes the projection lens module more suitable for application scenarios with limited space, such as home projectors and portable projection devices.

[0026] The projection lens module of this application achieves the design goals of a small throw ratio (TR=0.5) and a large offset (140%), enabling the projected image to reach a large size at a short projection distance while maintaining image clarity and brightness. It eliminates the need for a complex reflector bowl structure, reducing the manufacturing difficulty and cost of the product, and improving the overall performance and reliability of the lens.

[0027] In addition, the first lens uses a plastic aspherical lens, which has the advantages of low cost, easy processing, and light weight; the tenth lens uses a glass aspherical lens, which ensures high imaging quality and stability.

[0028] Other features and advantages of this specification will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0029] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of this specification and, together with their description, serve to explain the principles of this specification.

[0030] Figure 1 A schematic diagram of a standard projector installation and projection; Figure 2 This is a schematic diagram of the projection lens module used in a projection device according to an embodiment of this application. Figure 3 This is a schematic diagram of the optical architecture of the projection lens module provided in an embodiment of this application; Figure 4 This is a partial structural schematic diagram of the second lens provided in an embodiment of this application; Figure 5 A partial structural schematic diagram of the third lens provided in an embodiment of this application; Figure 6 The structure and optical path diagram of the projection lens module provided in Embodiment 1 of this application; Figure 7 The structure and optical path diagram of the projection lens module provided in Embodiment 2 of this application; Figure 8 The structure and optical path diagram of the projection lens module provided in Embodiment 3 of this application; Figure 9 The structure and optical path diagram of the projection lens module provided in Embodiment 4 of this application; Figure 10 The structure and optical path diagram of the projection lens module provided in Embodiment 5 of this application; Figure 11 The distortion diagram of the projection lens module provided in the embodiments of this application; Figure 12 The MTF diagram of the projection lens module provided in the embodiments of this application.

[0031] Explanation of reference numerals in the attached figures: 1. First lens; 2. Second lens; 3. Third lens; 4. Fourth lens; 5. Fifth lens; 6. Sixth lens; 7. Seventh lens; 8. Eighth lens; 9. Ninth lens; 10. Tenth lens; 11. Aperture; 12. Prism; 13. Display unit; 14. Glass plate. Detailed Implementation

[0032] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present application.

[0033] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application and its application or use.

[0034] Technologies and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such technologies and equipment should be considered part of the specification.

[0035] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0036] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0037] The projection lens module and projection device provided in the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0038] According to one embodiment of this application, a projection lens module is provided, see [link to relevant documentation]. Figure 3, the projection lens module comprises a first lens group, a diaphragm and a second lens group which are sequentially arranged along the same optical axis. The first lens group comprises a first lens 1, a second lens 2, a third lens 3, a fourth lens 4 and a cemented doublet which are sequentially arranged along the optical axis, wherein the first lens 1, the second lens 2 and the third lens 3 all have negative optical power, and the fourth lens 4 and the cemented doublet both have positive optical power. The second lens group comprises a cemented triplet and a tenth lens 10 arranged along the optical axis, wherein the cemented triplet has negative optical power and the tenth lens 10 has positive optical power. The diaphragm 11 is located between the cemented doublet and the cemented triplet, the distance between the diaphragm 11 and the cemented doublet is L1, the distance between the diaphragm 11 and the cemented triplet is L2, and L1 and L2 satisfy: 3.3<L1 / L2<4. The first lens 1 is a plastic aspheric lens, and the tenth lens 10 is a glass aspheric lens.

[0039] In the current market for home projectors, desktop projection is a common projection mode. However, see Figure 1 , this projection mode has two significant pain points that restrict its user experience and market promotion.

[0040] The first pain point is the space occupation problem.

[0041] see Figure 1 , traditional projectors for desktop projection usually require a large installation space to ensure the integrity and definition of the projected image. This demand imposes strict restrictions on the placement of projectors in living rooms, which not only occupies space resources, but also may affect the overall layout and aesthetics of the living room. This pain point is particularly prominent for users with small living spaces, who are often unable to install or use the projector due to insufficient space (i.e., Figure 1 the conventional projector shown therein).

[0042] The second pain point is that no obstructions are allowed.

[0043] Another significant pain point is that no obstructions are allowed in the projection optical path of traditional projectors. Once an object blocks the optical path, it will cause the projected image to be missing or deformed, which seriously affects the viewing effect. This restriction requires that no items be placed on the projection path when using the projector. This not only brings a lot of inconvenience to users' daily use, but also limits the flexibility and application scenarios of the projector.

[0044] In order to solve the above two pain points, the present application proposes an optical design of a short-focus projection lens module. The short-focus projection technology has the characteristics of small projection ratio and large offset, and can realize a large projected image within a short projection distance, see Figure 2This effectively reduces the space required for projector installation.

[0045] Specifically, the projection lens module design provided in this application achieves excellent performance with a throw ratio of 0.5 and an offset of 140%. This optical design not only significantly reduces the installation space requirements of the projection device (which has the projection lens module of this application built in), allowing users to use the projection device in a smaller space, but also increases the offset value so that the projected image is further away from the projection device itself, effectively preventing the projection device itself from obstructing the projected image.

[0046] The projection lens module provided in the embodiments of this application will be described in detail below.

[0047] The projection lens module provided in this application mainly includes an optical component such as a projection lens and a display unit 13. The projection lens is designed to be located in the light-emitting path of the display unit 13, see [link to relevant documentation]. Figure 3 The projection lens is responsible for receiving the light emitted from the display unit 13 (this light is dedicated to projection display) and modulating and focusing it. After this series of optical processes, the light is projected onto the imaging surface to form a clear projected image.

[0048] See Figure 3 The projection lens provided in this application embodiment includes two lens groups: a first lens group and a second lens group. The first lens group (in...) Figure 3 The middle mirror (located on the left) is further away from the display unit 13 compared to the second mirror group. The second mirror group (located on the left) Figure 3 The lens group (located on the right) is positioned close to the display unit 13. Furthermore, an aperture 11 is provided between these two lens groups to optimize light transmission and imaging effects.

[0049] The first and second lens groups are described in detail below.

[0050] The first lens group provided in this embodiment includes, for example, a total of six lenses. Specifically, see... Figure 3 The first lens group is designed to consist of a first lens 1, a second lens 2, and a third lens 3 with negative optical power, a fourth lens 4 with positive optical power, and a cemented doublet lens.

[0051] In other words, the first lens group consists of three negative power lenses arranged sequentially along the optical axis: lens 1, lens 2, and lens 3. This combination of three negative lenses not only expands the field of view but also effectively corrects field curvature. The characteristic of negative lenses lies in their ability to diverge light; through reasonable design of optical parameters such as curvature and center thickness, light passing through these three negative lenses plays a crucial role in field curvature correction. Following these three negative lenses, the first lens group also includes a positive power lens 4. The addition of this positive lens effectively balances the negative power generated by the preceding three negative lenses, resulting in a more reasonable power distribution throughout the first lens group. This combination of positive and negative lenses helps reduce aberrations and improve image quality. The cemented doublet lens, as the last element of the first lens group, not only further balances the power distribution with its positive power characteristic but also effectively corrects chromatic aberration through its unique cemented structure.

[0052] By employing three negative power lenses as the starting part of the first lens group, the optical design of this application can expand the field of view to 55°~59°. This wide field of view design allows the projection lens module to be applied to a wider range of projection scenarios, meeting diverse user needs. At the same time, due to the introduction of positive power lenses and cemented doublet lenses, this application also effectively controls distortion and chromatic aberration.

[0053] The projection lens module provided in this application embodiment has a second lens group that, as a key component of the entire projection lens, works in conjunction with the first lens group to achieve excellent optical performance. The following is a detailed description of the technical effects of the second lens group and its related design.

[0054] The second lens group mainly consists of a cemented triplicate lens and a tenth lens 10, employing a unique "cemented triplicate (negative)-positive" structural design. This structural design fully utilizes the complex refractive characteristics of the cemented triplicate lens, effectively correcting aberrations through its negative optical power portion and improving image quality.

[0055] The tenth lens 10, as a positive power lens, further enhances the projection imaging capability of the projection lens. It not only balances the negative power of the cemented triplet lens but also improves the light-gathering effect, making the projected image clearer and brighter.

[0056] By adopting the above structural design, the projection lens module provided in this application embodiment can maintain excellent imaging quality across the entire field of view (55°~59°). A clear image effect can be presented in both the center and the edges of the image. This excellent full-field imaging quality benefits from the precise aberration correction of the second lens group and the enhanced light-converging capability of the tenth lens 10.

[0057] Furthermore, the design of the second lens group not only focuses on improving optical performance but also fully considers the compactness of the module. Through careful arrangement of the position and shape of each lens, the overall size of the second lens group is effectively controlled. This compact design not only reduces production costs but also makes the projection lens module more suitable for space-constrained applications. At the same time, it ensures that the projection lens module maintains high performance while possessing wider applicability.

[0058] In the projection lens module provided in this application embodiment, the aperture stop 11 is positioned between the cemented dot lens and the cemented triplet lens. This design is based on a comprehensive consideration of the light propagation path, aberration correction, and overall structural layout.

[0059] The aperture stop 11, as an important optical element in the projection lens module, plays a crucial role in aberration correction due to its position. Positioning it between the cemented doublet and the cemented triplicate lens effectively balances the aberration correction capabilities of the first lens group (including all lenses before the cemented doublet) and the second lens group (including the cemented triplicate and all lenses after it).

[0060] This positioning facilitates the coordinated operation of the first and second lens groups, allowing them to jointly achieve excellent imaging performance across the entire field of view by each undertaking a portion of aberration correction tasks. Specifically, the cemented doublet lens, as an important component of the first lens group, primarily corrects advanced aberrations such as astigmatism; while the cemented triplicate lens, through its complex refractive properties, effectively corrects various aberrations such as spherical aberration and chromatic aberration. The aperture stop 11 is positioned precisely between these two, playing a crucial role in bridging the gap between them.

[0061] The aperture 11 is not only a light-passing aperture, but it also restricts the light beam entering the projection lens. By controlling the aperture size, it can be ensured that only light rays within a specific angle and range can participate in imaging, thereby effectively reducing stray light and ghosting. This restriction of the light beam is of great significance for improving image sharpness and contrast. It ensures that the imaging light rays propagate more concentratedly and orderly to the imaging surface, avoiding image blurring and distortion caused by stray light and ghosting.

[0062] Furthermore, the position of the aperture stop 11 also affects the overall structural layout of the projection lens. Placing it between the cemented dodecyl lens and the cemented triplex lens helps to achieve a compact design of the projection lens module.

[0063] In summary, the diaphragm 11 is arranged between the doublet lens and the triplet lens, which not only achieves balance and optimization of aberration correction, but also improves imaging quality and realizes a compact design, providing support for the development of projection lens modules in the direction of high performance and low cost.

[0064] In the projection lens module provided in the embodiment of the present application, the diaphragm 11 is placed between the doublet lens and the triplet lens, the distance L1 between the diaphragm 11 and the doublet lens and the distance L2 between the diaphragm 11 and the triplet lens satisfy a specific proportional relationship: 3.3<L1 / L2<4. This design not only effectively balances the aberration correction capabilities of the first lens group and the second lens group, but also reduces the generation of stray light and ghost images by limiting the propagation path of the light beam, thereby significantly improving the clarity and contrast of the image.

[0065] The present application adopts a compact optical architecture, and by reasonably arranging the positions of each lens and arranging the diaphragm 11 (located between the doublet lens and the triplet lens, and satisfying the spacing proportional relationship of 3.3<L1 / L2<4), the total optical length is effectively shortened. The total optical length of the entire projection lens module can be controlled within 78 mm for example, and the maximum aperture does not exceed 47 mm, which greatly reduces the volume and weight. This compact design not only reduces production costs, but also makes the projection lens module more suitable for application scenarios with limited space, such as home projectors and portable projection devices.

[0066] In the projection lens module provided in the embodiment of the present application, the first lens 1 is a plastic aspheric lens, and the tenth lens 10 is a glass aspheric lens. The selection of these two materials not only takes cost effectiveness into consideration, but also fully considers their respective optical characteristics. Plastic aspheric lenses have the advantages of low cost, light weight, and easy processing and molding. Glass aspheric lenses have excellent optical performance and thermal stability, which can ensure that the projection lens can maintain stable imaging quality after long-term use.

[0067] The projection lens module according to the embodiment of the present application achieves the design objectives of small throw ratio (TR=0.5) and large offset (140%), enabling the projected image to obtain a larger size within a shorter projection distance while maintaining the clarity and brightness of the image. It does not require a complex reflection bowl structure, which reduces the processing difficulty and cost of the product, and improves the overall performance and reliability of the lens.

[0068] The total optical length of the projection lens module according to the embodiment of the present application can be controlled within 78 mm, and the maximum aperture does not exceed 47 mm. While achieving TR=0.5 and short-focus performance, this design reduces the volume, making it more suitable for application scenarios with limited space.

[0069] The projection lens module provided in this application, with its excellent optical performance and compact design, is suitable for various home viewing projection devices, especially micro-projection and other fields, and has broad application prospects.

[0070] In some examples of this application, the center thickness T' of the cemented lens satisfies 8.5%≤T' / TTL≤10%; where TTL is the total optical length of the projection lens module.

[0071] In the example provided in this application, a thickness design is proposed for the cemented triplet lens in the projection lens module, wherein the center thickness T' of the cemented triplet lens and the total optical length TTL of the projection lens module should satisfy a proportional relationship of 8.5% ≤ T' / TTL ≤ 10%. This design plays a key role in optimizing the optical performance of the projection lens module, ensuring structural compactness, and improving chromatic aberration correction capabilities.

[0072] As a key component in the projection lens module, the thickness (center thickness T') of the cemented triplet lens directly affects the chromatic aberration correction capability of the projection lens module. By setting the T' / TTL ratio, it can be ensured that the cemented triplet lens provides sufficient chromatic aberration correction without introducing other unnecessary optical aberrations. This ratio range (8.5% to 10%) is based on a comprehensive evaluation of various optical performance indicators and aims to achieve the optimal balance between chromatic aberration correction and other optical performance characteristics.

[0073] With the continuous development of projection technology, the requirements for miniaturization and weight reduction of the entire projection lens module are increasing. By setting a reasonable T' / TTL ratio range, a compact design of the projection lens module can be achieved while ensuring optical performance. This helps to reduce the overall size and weight of the projection lens module, improving its portability and applicability.

[0074] The cemented triplet lens is composed of multiple lens elements with different refractive indices, and its center thickness has a significant impact on the chromatic aberration correction effect. While a thicker cemented triplet lens can provide stronger chromatic aberration correction capabilities, it may increase the size and weight of the entire projection lens module; conversely, a thinner cemented triplet lens may not meet the chromatic aberration correction requirements. By setting a ratio range of 8.5% to 10%, the chromatic aberration correction effect can be ensured while avoiding an excessive increase in the size of the projection lens module.

[0075] By precisely controlling the ratio of the center thickness T' to the TTL of the triplex lens, its chromatic aberration correction effect can be further optimized, improving the imaging quality of the projection lens module. This is of great significance for users who pursue high-quality projection effects.

[0076] In addition to improving chromatic aberration correction capabilities, controlling the center thickness T' of the cemented triplex lens can also positively impact other optical performance characteristics of the projection lens module (such as spherical aberration and coma). By optimizing the T' / TTL ratio, the overall imaging quality of the projection lens module can be further improved, meeting users' demands for high-definition and high-contrast projection effects.

[0077] While ensuring optical performance, a compact design of the projection lens module can be achieved by setting a reasonable T' / TTL ratio range. This helps reduce the overall size and weight of the projection lens module, improving its portability and applicability.

[0078] See some examples in this application. Figure 3 The three-layer cemented lens is composed of a seventh lens 7, an eighth lens 8, and a ninth lens 9 cemented together in sequence, wherein: the seventh lens 7 and the ninth lens 9 are both positive optical power; the eighth lens 8 is negative optical power; and the refractive index of either the seventh lens 7 or the ninth lens 9 is lower than the refractive index of the eighth lens 8.

[0079] See Figure 3 The cemented triplet lens is located in the second lens group of the projection lens, adjacent to the aperture stop 11. This arrangement helps optimize the light propagation path and aberration correction. The cemented triplet lens is composed of a seventh lens 7, an eighth lens 8, and a ninth lens 9 cemented together in sequence to form a compact optical unit.

[0080] The seventh lens 7 and the ninth lens 9: Both lenses are designed with positive optical power, and they function to converge light rays in the optical path. By rationally designing the curvature and center thickness of these two lenses, effective convergence of light rays can be achieved, providing a foundation for forming a clear projected image.

[0081] The eighth lens 8 differs from the seventh lens 7 and the ninth lens 9 in that it is designed with negative optical power, meaning it serves to diverge light rays. The combination of a negative optical power lens and a positive optical power lens allows for precise control of light, thereby correcting various aberrations such as spherical aberration and astigmatism.

[0082] Of particular note is that the refractive index of either the seventh lens 7 or the ninth lens 9 is lower than that of the eighth lens 8. Materials with different refractive indices have different abilities to deflect light. By selecting materials with lower refractive indices for positive power lenses (seventh lens 7 and ninth lens 9) and materials with higher refractive indices for negative power lenses (eighth lens 8), more precise control over light can be achieved. Specifically, this design of refractive index difference helps to: (1) Correction of astigmatism and field curvature: By reasonably combining lenses with different refractive indices, the direction of light propagation can be adjusted, thereby effectively correcting aberrations such as astigmatism and field curvature, and improving the clarity and flatness of the image.

[0083] (2) Controlling color difference: Color difference is one of the key issues to be considered in the design of projection lens modules. By selecting a suitable combination of materials, the offset of different wavelengths of light at the focal point can be reduced, that is, color difference can be controlled, thereby further improving the color reproduction and clarity of the projected image.

[0084] In summary, the triple-cemented lens design in this example achieves precise control of light and effective aberration correction by accurately controlling the differences in optical power and refractive index of the lenses. This design not only optimizes the imaging quality of the projection lens module but also improves its overall performance and reliability. Furthermore, this design facilitates the compactness and miniaturization of the lens, making it more suitable for space-constrained applications, such as micro-projection devices.

[0085] See the examples in this application. Figure 3 The three-layer cemented lens is composed of a seventh lens 7, an eighth lens 8, and a ninth lens 9 cemented together in sequence. The seventh lens 7 and the ninth lens 9 are both positive power lenses, and their refractive indices are defined as N1 and N2, respectively. The eighth lens 8 is a negative power lens, and its refractive index is defined as N3.

[0086] The seventh lens 7 and the ninth lens 9 are positive power lenses, and their refractive indices are relatively low (N1 and N2). In optical design, positive power lenses are mainly used to converge light rays, and the lower refractive index helps to reduce the deflection angle of light rays in the lens, thereby reducing aberrations such as spherical aberration and astigmatism to a certain extent.

[0087] The eighth lens 8 is a negative power lens with a relatively high refractive index N3. Negative power lenses are used to diverge light, and the higher refractive index enhances their diverging ability. By combining a high-refractive-index negative lens (N3) with low-refractive-index positive lenses (N1 and N2), more precise control of light can be achieved, thereby more effectively correcting aberrations such as astigmatism and field curvature.

[0088] Refractive index difference is not only a key factor in correcting aberrations but also an important means of controlling chromatic aberration. Chromatic aberration is one of the key issues to consider in the design of projection lens modules, as it causes light of different wavelengths to shift at the focal point, affecting image sharpness. In this application, by controlling the refractive index ratio between the eighth lens 8 (a high-refractive-index negative lens), the seventh lens 7, and the ninth lens 9 (a low-refractive-index positive lens) can be controlled more effectively to reduce the shift of light of different wavelengths at the focal point, thereby controlling chromatic aberration and improving image sharpness and color reproduction.

[0089] In summary, the triple-cemented lens design in this application achieves finer control of light and effective aberration correction by controlling the refractive indices and their ratios among the three lenses. This design not only significantly improves the optical performance of the projection lens module but also enhances the color reproduction and clarity of the projected image. Furthermore, this design contributes to the compactness and miniaturization of the projection lens module, meeting the demands of modern projection devices for lightweight design and portability.

[0090] In one example, the seventh lens 7 and the ninth lens 9 are both positive lenses with a refractive index range of 1.49 to 1.56; the eighth lens 8 is a negative lens with a refractive index range of 1.87 to 1.92.

[0091] Both the seventh lens 7 and the ninth lens 9 have positive optical power, and their refractive index is set between 1.49 and 1.56. This refractive index range corresponds to some low-refractive-index optical materials, which have good transmittance and low dispersion characteristics.

[0092] The eighth lens 8 has a negative optical power and its refractive index is set between 1.87 and 1.92. This refractive index range corresponds to some high refractive index optical materials, which can achieve thinner lenses at the same optical power, and also help to correct chromatic aberration.

[0093] The combination of a high-refractive-index negative power lens and a low-refractive-index positive power lens allows for precise adjustment of the refraction path for light of different wavelengths, thereby reducing color distortion and improving the color reproduction and clarity of the image.

[0094] High-refractive-index negative-power lenses can achieve a thinner profile while maintaining the same optical power, which helps reduce the size and weight of the entire projection lens module and enables a more compact design.

[0095] Furthermore, materials with different refractive indices have different coefficients of thermal expansion and mechanical properties. By rationally combining these materials, this application can reduce changes in optical performance caused by temperature variations or mechanical stress, thereby enhancing the stability of the entire projection lens module.

[0096] In the example provided in this application, the cemented triplet lens, as an important component of the projection head module, has one of its main functions: correcting chromatic aberration. Chromatic aberration is a key issue that needs to be overcome in lens design, as it causes light of different wavelengths to shift at the focal point, thus affecting image sharpness. By controlling the center thickness ratio of the positive and negative lenses (the seventh lens 7 and the ninth lens 9 are positive, and the eighth lens 8 is negative), the chromatic aberration correction capability of the cemented triplet lens can be further optimized. This optimization helps reduce the shift of light of different wavelengths at the focal point, thereby significantly improving the color reproduction and contrast of the projection lens module.

[0097] In addition to chromatic aberration correction, the cemented triplicate lens can also control other aberrations such as spherical aberration and coma to a certain extent. These aberrations also affect image quality, leading to image blurring or distortion.

[0098] By adjusting the center thickness ratio of the positive and negative lenses in the cemented triplet lens, the correction effect of these aberrations can be further optimized. This optimization helps to improve image sharpness and resolution, making the projected image more delicate and realistic.

[0099] Furthermore, while ensuring optical performance, a compact design for the projection lens module can be achieved by setting a reasonable range for the lens center thickness ratio. This compact design not only helps reduce the size and weight of the device but also lowers production costs.

[0100] The triple-layer lens thickness ratio design in this example achieves effective correction of chromatic aberration and aberrations by precisely controlling the center thickness ratio of the positive and negative lenses, while ensuring the compactness and lightweight nature of the projection lens module. This design not only significantly improves the optical performance of the projection lens module but also supports its application in various projection devices.

[0101] See some examples in this application. Figure 3 The cemented doublet lens is composed of a fifth lens 5 and a sixth lens 6 cemented together, wherein: the optical powers of the fifth lens 5 and the sixth lens 6 are opposite, one of the fifth lens 5 and the sixth lens 6 has a positive optical power and the other has a negative optical power, and the refractive index of the lens with positive optical power is higher than that of the lens with negative optical power.

[0102] In the example provided in this application, the cemented doublet lens in the projection lens module is another important optical element, and its design has a significant impact on improving the optical performance of the entire projection lens module. The cemented doublet lens is composed of a fifth lens 5 and a sixth lens 6 bonded together. Its unique design feature is that the optical powers of the fifth lens 5 and the sixth lens 6 are opposite; one has a positive optical power, and the other has a negative optical power. This design combination plays an important role in the projection lens module, helping to achieve precise control of light and effective correction of aberrations.

[0103] The fifth lens 5 and the sixth lens 6 have opposite optical powers; one is responsible for converging light (positive optical power), and the other is responsible for diverging light (negative optical power). This design combination can cleverly balance the convergence and divergence of light, thereby reducing aberrations such as spherical aberration and astigmatism to a certain extent.

[0104] Based on the opposite optical power, this example further specifies that the refractive index of the positive optical power lens (fifth lens 5) is N5, and the refractive index of the negative optical power lens (sixth lens 6) is N6, satisfying the condition N5 > N6. This difference in refractive index is designed based on the characteristics of optical materials and the principle of aberration correction. Materials with higher refractive indices have stronger light-converging or diverging capabilities; therefore, by selecting a suitable combination of materials with appropriate refractive indices, the optical performance of the cemented doublet lens can be further optimized.

[0105] The opposing optical powers of the cemented doublet lenses allow light to converge and diverge or diverge and converge as it passes through the lenses, a process that helps balance aberrations during light propagation. Furthermore, by controlling the refractive index difference between the two lenses, the control of light can be further refined, thereby achieving higher precision aberration correction.

[0106] The design of the cemented doublet lens effectively improves the optical performance of the entire projection lens module. It reduces aberrations, improves image sharpness, and enhances key indicators such as color reproduction and contrast. This is especially important for projection devices, as they need to present high-quality, high-definition images to meet users' viewing needs.

[0107] The design of cemented doublet lenses also helps to achieve compactness and miniaturization of the lens. By cementing the two lenses together, the overall size of the projection lens module can be reduced, thereby meeting the requirements of modern projection devices for lightweight and portability.

[0108] The cemented doublet lens design provided in this example achieves precise control of light and effective correction of aberrations by controlling the difference in optical power and refractive index between the two lenses. This design not only significantly improves the optical performance of the projection lens module, but also supports the compactness and miniaturization of the projection lens module.

[0109] In some examples of the present application, the fifth lens (5) has positive optical power and a refractive index of N5, the sixth lens (6) has negative optical power and a refractive index of N6, and the relationship between N5 and N6 satisfies: 1.03 < N5 / N6 < 1.1.

[0110] As a key component in the projection lens module, one of the design objectives of the cemented doublet lens is to correct aberrations in the projection lens module. By setting the refractive index ratio of 1.03 < N5 / N6 < 1.1, the refractive indexes of the positive lens and the negative lens are precisely controlled. This appropriate refractive index ratio can effectively enhance the aberration correction capability of the cemented doublet lens for aberrations such as spherical aberration and astigmatism. A higher refractive index ratio means that the converging effect of the positive lens on light is relatively strong, while the diverging effect of the negative lens is relatively weak. This design combination helps to balance aberrations during light propagation, thereby improving imaging quality.

[0111] In addition to enhancing the aberration correction capability, the design of this refractive index ratio also helps optimize the overall optical performance of the cemented doublet lens. By precisely controlling the refractive index ratio of the lenses, the propagation path and convergence point position of light can be better regulated, thereby reducing the spot size and improving key optical indicators such as resolution and contrast. This is particularly important for projection devices, since they need to present high-quality, high-definition images to meet users' viewing requirements.

[0112] In one example, the fifth lens (5) is a positive lens, and the refractive index N5 of the positive lens ranges from 1.88 to 1.95; the sixth lens (6) is a negative lens, and the refractive index N6 of the negative lens ranges from 1.75 to 1.82.

[0113] In the above example, the fifth lens (5) is a positive lens, which is the converging component in the cemented doublet lens, and its refractive index N5 is in a relatively high range. A positive lens with a high refractive index can converge light more effectively, thereby improving the imaging capability of the projection lens module. The sixth lens (6) is a negative lens, and in comparison, the refractive index N6 of this negative lens is slightly lower. The main function of the negative lens is to diverge light, and it cooperates with the positive lens to jointly realize the regulation of light.

[0114] According to the examples provided by the present application, by controlling the refractive index ratio of the positive lens and the negative lens, the cemented doublet lens can correct aberrations better. The converging effect of the positive lens and the diverging effect of the negative lens cancel each other out, and the appropriate refractive index ratio ensures that this canceling effect is more precise and effective, thereby reducing the refraction error of light during propagation and improving imaging quality.

[0115] The difference in refractive index is also a means for controlling chromatic aberration. By setting an appropriate refractive index ratio, a doublet lens can reduce the shift of light of different wavelengths at the focal point, that is, chromatic aberration, to a certain extent. This is crucial for improving the color reproduction and sharpness of imaging.

[0116] Combining the above advantages in aberration correction and chromatic aberration control, the doublet lens design in the example of the present application significantly improves the imaging quality of the projection lens module, including improvements in image resolution, contrast, color saturation and other aspects, bringing users a higher-quality visual experience.

[0117] In some examples of the present application, the first lens group satisfies: 0.95<T3 / (T1+T2)<1.3, wherein: T1 is the central thickness of the first lens 1, T2 is the central thickness of the second lens 2, and T3 is the central thickness of the third lens 3.

[0118] In the examples provided by the present application, a specific design of central thickness ratio of lenses is proposed for the first lens group in the projection lens module (consisting of three negative lenses: the first lens 1, the second lens 2, and the third lens 3). Specifically, a specific proportional relationship needs to be satisfied among the central thickness T1 of the first lens 1, the central thickness T2 of the second lens 2, and the central thickness T3 of the third lens 3, that is 0.95<T3 / (T1+T2)<1.3. This design plays a key role in optimizing the optical performance, structural compactness and environmental adaptability of the projection lens module.

[0119] The central thickness of a lens is one of the important factors affecting its imaging performance. In the present application, by controlling the central thickness ratio of the three negative lenses in the first lens group, their convergence and divergence effects on light can be effectively optimized, thereby achieving more effective aberration correction. An appropriate thickness ratio helps to balance the degree of light deflection of each lens, reduce deflection errors of light during propagation, and thus improve imaging quality.

[0120] On the premise of ensuring imaging quality, by controlling the central thickness ratio of the lenses, the compact design of the projection lens module can also be achieved. Smaller lens thickness helps reduce the volume and weight of the projection lens module, making it more suitable for application scenarios with limited space, such as micro projection devices.

[0121] A reasonable central thickness ratio of lenses also helps to ensure the stability of the projection lens module in different environments. Under conditions such as temperature changes or mechanical vibrations, an appropriate central thickness ratio of lenses can reduce changes in imaging quality caused by lens deformation, and improve the reliability and durability of the projection lens module. This is particularly important for projection equipment that needs to be used in different environments.

[0122] In summary, the first lens group lens center thickness ratio design proposed in this example significantly optimizes the optical performance, structural compactness, and environmental adaptability of the projection lens module by precisely controlling the center thickness ratio of the three negative lenses.

[0123] In some examples of this application, the center thickness T1 of the first lens 1 satisfies 3.3%≤T1 / TTL≤3.7%; the center thickness T2 of the second lens 2 satisfies 1.5%≤T2 / TTL≤1.8%; where TTL is the total optical length of the projection lens module.

[0124] In some examples of this application, specific proportional constraints are proposed between the center thickness of the lens and the total optical length (TTL) of the projection lens module for the first lens group (mainly composed of negative lenses such as first lens 1 and second lens 2). Specifically, the center thickness T1 of the first lens 1 must satisfy 3.3% ≤ T1 / TTL ≤ 3.7%, while the center thickness T2 of the second lens 2 must satisfy 1.5% ≤ T2 / TTL ≤ 1.8%. This design constraint plays an important role in optimizing the optical performance of the entire projection lens module, ensuring structural compactness, and improving manufacturing feasibility.

[0125] As a component of the projection lens module, the ratio of the center thickness T1 to the total thickness (TTL) of the first lens 1 directly affects the imaging quality of the projection lens. By setting a ratio range of 3.3% ≤ T1 / TTL ≤ 3.7%, it is possible to ensure that the first lens has sufficient thickness to provide good imaging performance and aberration correction capabilities, while avoiding the increase in size and weight caused by an excessively thick lens. This ratio range is selected based on a comprehensive consideration of lens imaging performance, aberration correction, and lens structural compactness.

[0126] The thickness ratio design of the second lens 2, i.e., 1.5%≤T2 / TTL≤1.8%, is equally important. It helps to balance the imaging performance of the entire projection lens module, ensures effective cooperation between the lenses, and jointly achieves fine control of light and effective correction of aberrations.

[0127] By controlling the ratio of lens center thickness to TTL (Total Thickness), a compact design of the projection lens module can be achieved while maintaining image quality. A smaller lens thickness ratio helps reduce the overall size and weight of the projection lens module, making it more suitable for space-constrained applications.

[0128] In addition, reasonable design of the lens thickness ratio also helps improve the manufacturing feasibility of the projection lens module. Thinner lenses may face higher difficulty and cost during processing, while excessively thick lenses may increase material consumption and processing time. By setting an appropriate range of the ratio between lens thickness and TTL, it is possible to ensure imaging quality and structural compactness while reducing manufacturing difficulty and cost, and improving the production efficiency and economic benefits of the product.

[0129] In some examples of the present application, the sag of the surface of the second lens 2 on a side away from the diaphragm 11 at the maximum aperture is S1, and the sag of the surface on a side close to the diaphragm 11 at the maximum aperture is S2, and 3.5<S2 / S1<4.5 is satisfied.

[0130] In the examples provided by the present application, a specific sag ratio design constraint is proposed for the second lens 2 in the projection lens module. Specifically, the sag of the surface of the second lens 2 on the side away from the diaphragm 11 at the maximum aperture is defined as S1, and the sag of the surface on the side close to the diaphragm 11 at the maximum aperture is defined as S2, and S1 and S2 need to satisfy the condition: 3.5<S2 / S1<4.5. This design constraint plays a key role in improving the optical performance of the projection lens module, optimizing light propagation paths, and enhancing aberration correction capability.

[0131] Sag is an important parameter describing the shape of a lens surface, and it directly affects the propagation path of light. By controlling the sag ratio (S2 / S1) of the two surfaces of the second lens 2, the deflection angle and path of light when passing through the second lens 2 can be optimized, thereby reducing light loss and distortion during propagation.

[0132] Reasonable setting of the sag ratio helps enhance the aberration correction capability of the second lens 2. Aberration is one of the main influencing factors on the imaging quality of a projection lens module, including spherical aberration, coma, astigmatism, etc. By adjusting the sag ratio of the second lens 2, these aberrations can be effectively corrected, thereby improving the clarity and resolution of the image.

[0133] Especially for primary aberrations such as spherical aberration and coma, control of the sag ratio is particularly important. These aberrations are often caused by inconsistent deflection angles or asymmetric light paths when light passes through the lens. By setting the range of the ratio S2 / S1, light can maintain a more consistent deflection angle and a more symmetric path when passing through the second lens 2, thereby reducing the influence of these aberrations.

[0134] In summary, by controlling the sag ratio (S2 / S1) of the second lens 2, the light propagation path can be optimized and the aberration correction capability can be enhanced, thereby improving the optical performance of the entire projection lens module. This design constraint not only improves imaging quality, but also provides support for high-quality imaging of projection equipment in various application scenarios.

[0135] In the example of the present application, the sag ratio design of the second lens proposed by precisely controlling the sag ratio (S2 / S1) of the two surfaces significantly optimizes the optical performance of the projection lens module. This design not only optimizes the light propagation path and reduces light loss and distortion, but also enhances the aberration correction capability of the lens and improves the clarity and resolution of the image.

[0136] In some examples of the present application, see Figure 4 , the angle between the tangent at the maximum aperture of the surface of the second lens 2 away from the stop 11 and the optical axis is A1, and the angle between the tangent at the maximum aperture of the surface close to the stop 11 and the optical axis is A2, which satisfies: 40°<A1-A2<50°, and 1.8<A1 / A2<2.3.

[0137] In the example provided by the present application, fine optical design is performed for the second lens 2 in the projection lens module, in particular, the angles between the tangents at the maximum aperture of the surface away from the stop 11 and the surface close to the stop 11 and the optical axis (recorded as A1 and A2 respectively) are controlled. Specifically, it is required to satisfy 40°<A1-A2<50°, and 1.8<A1 / A2<2.3. This design plays a key role in optimizing the light deflection angle, reducing distortion and improving the overall optical performance of the projection lens module.

[0138] By controlling the magnitudes and relationship of A1 and A2, the deflection angle of light when passing through the second lens 2 can be optimized. The appropriate angle difference (40°<A1-A2<50°) ensures that the deflection of light in the second lens 2 is neither too sharp nor too gentle, thereby helping to correct aberrations introduced by other lenses and improving imaging quality.

[0139] At the same time, the setting of the angle ratio (1.8<A1 / A2<2.3) further refines the control of the light deflection angle, enabling light to be distributed more uniformly inside the projection lens module and reducing loss and distortion during the light deflection process.

[0140] Distortion is an important aberration index in the projection lens module, which directly affects the fidelity of the projected image and the user's visual experience. The present application significantly reduces the distortion of the entire projection lens module by controlling the relationship between the angle between the tangent at the maximum aperture of the second lens 2 and the optical axis.

[0141] Even at a large field of view of 55° to 59°, the projection lens module of the present application can still control distortion at a low level (e.g., within 1.5%), which is about 30% lower than that of similar products. This achievement benefits from the fine design of the included angle between the tangent of the second lens 2 and the optical axis, which effectively optimizes the propagation path and deflection angle of light rays.

[0142] Through the above design, the projection lens module of the present application achieves a significant improvement in optical performance. The improved imaging quality makes the projected image clearer and more realistic with higher color reproducibility, thereby enhancing the user's visual experience. At the same time, the low distortion level also ensures the shape fidelity of the projected image, avoids the shape distortion problem caused by distortion, and further improves the user's visual experience.

[0143] In summary, in the example of the present application, the design of the included angle between the tangent of the second lens 2 and the optical axis significantly optimizes the deflection angle of light, reduces distortion and improves the overall optical performance of the projection lens module by precisely controlling the magnitudes of A1 and A2 and their relationship. While ensuring imaging quality, this design also enhances the user's visual experience, and provides strong support for the technological progress and application expansion in the field of projection lenses. In addition, in combination with other optical designs of the projection lens module (such as the "negative-negative-negative-positive-doublet (positive)" structure of the first lens group and the "triplet (negative)-positive" structure of the second lens group), the projection lens module of the present application achieves reasonable power distribution and excellent imaging quality, demonstrating its outstanding technical advantages and application prospects.

[0144] In some examples of the present application, see Figure 5 , the included angle between the tangent at the maximum caliber of the surface of the third lens 3 away from the stop 11 and the optical axis is A3, and the included angle between the tangent at the maximum caliber of the surface of the third lens 3 close to the stop 11 and the optical axis is A4, which satisfies: 40°<A3-A4<60°, and 1.6<A3 / A4<2.1.

[0145] In the examples provided by the present application, specific angle constraint conditions are proposed for the third lens 3 in the projection lens module, and these conditions are closely related to the included angles between the tangents at the maximum caliber of the two surfaces of the third lens 3 and the optical axis. Specifically, see Figure 5 , the included angle between the tangent at the maximum caliber of the surface of the third lens 3 away from the stop 11 and the optical axis is denoted as A3, and the included angle between the tangent at the maximum caliber of the surface of the third lens 3 close to the stop 11 and the optical axis is denoted as A4. These two angles need to satisfy the following constraint conditions: 40°<A3-A4<60°, and 1.6<A3 / A4<2.1. This design plays an important role in optimizing the optical performance of the projection lens module.

[0146] Control of the angle difference A3-A4 (40°<A3-A4<60°) is important for optimizing the deflection degree and direction of light passing through the third lens 3. An appropriate angle difference helps balance the converging and diverging effects of light in the lens, thereby effectively reducing aberration and improving imaging quality. This design is based on in-depth understanding of light propagation characteristics and aberration generation mechanisms, ensuring that light can maintain good parallelism and directivity after passing through the third lens 3.

[0147] Meanwhile, the constraint of the angle ratio A3 / A4 (1.6<A3 / A4<2.1) further refines the control over the shape and optical path design of the third lens 3. A reasonable angle ratio helps ensure the rationality of the lens shape and the stability of the optical path design, reducing imaging quality problems caused by lens shape changes or optical path offset.

[0148] By controlling the angle difference and angle ratio of the two surfaces of the third lens 3, the design in this example of the present application achieves fine regulation of light and effective correction of aberration. This not only reduces light loss and deflection error during propagation, but also improves light utilization and imaging quality.

[0149] Specifically, this design significantly improves the contrast, color reproduction and detail expression capability of the projection lens module. The clarity and resolution of the image are significantly improved, making the projected picture clearer, more delicate, with more real and full colors.

[0150] In addition to optimizing light deflection and aberration correction, the angle design in this example of the present application also takes into account the reliability and stability of lens design. By setting a reasonable angle ratio A3 / A4, the rationality of the shape of the third lens 3 and the stability of the optical path design are ensured. This helps reduce the influence of external factors (such as temperature changes, mechanical vibration, etc.) on the lens shape and optical path, and improves the reliability and durability of the projection lens.

[0151] In summary, the design of the included angle between the tangent and the optical axis for the third lens 3 in this example of the present application significantly optimizes light deflection, aberration correction and imaging quality by precisely controlling the angle difference and angle ratio. While ensuring the high optical performance of the projection lens module, this design also enhances the reliability and stability of the projection lens module design.

[0152] In some examples of the present application, see Figure 3 , the projection lens module further comprises a prism 12, a glass flat plate 14 and a display unit 13 which are sequentially arranged on a side of the tenth lens 10 away from the diaphragm 11.

[0153] In the example provided in this application, the projection lens module includes not only two lens groups and an aperture stop 11, but also a prism 12. Specifically, the prism 12 is located on the side of the tenth lens 10 away from the aperture stop 11. This is to deflect or reflect light to adapt to specific projection requirements or optical path layouts. Furthermore, the placement of the prism 12 can increase the functionality of the projection lens, such as changing the direction of the light path or achieving projection at a specific angle. At the same time, it is necessary to ensure the optical matching between the prism 12 and the lens groups to avoid additional aberrations or light loss.

[0154] In the specific implementation of the prism 12, a total internal reflection prism (TIR prism) design can be selected. With its efficient light reflection characteristics, the TIR prism can minimize light loss and ensure the brightness and color saturation of the projected image.

[0155] Meanwhile, the addition of the glass plate 14 provides an additional optical plane for the projection lens module, which may be used to adjust the phase and polarization state of light or as a protective window, further enhancing the stability and durability of the entire projection lens module. The display unit 13, as the source of the projected content, works closely with the prism 12, the glass plate 14, the two lens groups, and the aperture 11 to output a high-quality, high-definition projected image.

[0156] Specifically, the display unit 13, as a component of the projection lens module, is responsible for generating and providing projection light to the projection lens. The display unit 13 is, for example, a high-resolution display device, such as LCD, DLP, or LCOS, capable of generating high-quality image signals.

[0157] See some examples in this application. Figure 3 The ratio of the total optical length TTL of the projection lens module to the maximum aperture D1 of the lens in the projection lens satisfies: 1.5 < TTL / D1 < 1.9.

[0158] In the example provided in this application, the ratio between the total optical length (TTL) of the projection lens module and the maximum aperture (D1) of the lens was designed to ensure that this ratio falls within the range of 1.5 < TTL / D1 < 1.9. This design parameter directly affects several key aspects of the projection lens module, including its compactness, image quality, and manufacturing cost.

[0159] TTL, as the total optical length of a projection lens module, is an important standard for measuring lens size and compactness. By limiting the TTL to D1 ratio to between 1.5 and 1.9, the design of this application ensures sufficient light transmission capability (determined by D1) while clearly requiring a compact projection lens module. This balanced design enables the projection lens to achieve miniaturization and weight reduction while maintaining high-quality imaging, meeting the portability and space utilization needs of modern projectors.

[0160] D1, as the maximum aperture of the lens, not only affects the lens's light transmission capability but also directly relates to the rationality of the optical path design. By setting a reasonable TTL / D1 ratio range, this design helps optimize the optical path layout, reduce light loss and distortion during propagation, thereby improving image quality. See also [link to relevant documentation] in this application. Figure 3 The lens with the largest aperture is the first lens 1.

[0161] While maintaining image quality and compactness, controlling the TTL / D1 ratio also helps reduce the manufacturing cost of projection lenses. A shorter TTL means less material used and a simpler manufacturing process, thus reducing production costs. This is significant for improving the product's market competitiveness.

[0162] See some examples in this application. Figure 3 The effective focal lengths of each lens in the projection lens are as follows: The effective focal length of the first lens 1 is F1, -32mm≤F1≤-24mm; The effective focal length of the second lens 2 is F2, -19mm≤F2≤-14mm; The effective focal length of the third lens 3 is F3, -19mm≤F3≤-14mm; The effective focal length of the fourth lens 4 is F4, 25mm≤F4≤36mm; The effective focal length of the cemented doublet lens is F', 17mm≤F'≤25mm; The effective focal length of the triplex lens is F'', -80mm≤F''≤-55mm; The effective focal length of the tenth lens 10 is F10, 9mm≤F10≤14mm.

[0163] In the example provided in this application, the effective focal length range of the first lens (F1) is -32mm ≤ F1 ≤ -24mm. As the foremost lens of the projection lens module, the first lens 1 is responsible for collecting and correcting light. Its large negative focal length design helps to expand the field of view of the projection lens, enabling the projection lens module to capture a wider range of scenes. At the same time, this design also helps to reduce aberrations when light enters the projection lens module, providing a basis for the correction work of subsequent lenses.

[0164] The effective focal length range of the second lens (F2) and the third lens (F3) is -19mm ≤ F2, F3 ≤ -14mm. The second lens 2 and the third lens 3 have similar focal length ranges, and they jointly perform the function of further correcting aberrations. An appropriate negative focal length design not only helps reduce the overall length of the projection lens, achieving a compact design, but also effectively corrects aberrations generated during light propagation, improving image quality. The close cooperation between these two lenses ensures that light maintains good parallelism and directionality when passing through them.

[0165] The effective focal length range of the fourth lens (F4) is 25mm ≤ F4 ≤ 36mm. As the positive lens in the projection lens module, the main function of the fourth lens 4 is to deflect light rays, allowing them to pass smoothly through subsequent lens groups and converge onto the imaging surface. Its large positive focal length design helps to form a clear image, improving image contrast and detail. At the same time, the addition of the positive lens also helps to balance the optical power distribution in the lens module, improving the imaging performance of the entire system.

[0166] The effective focal length range of the cemented doublet lens (F') is 17mm ≤ F' ≤ 25mm. The cemented doublet lens is composed of two lenses with different refractive indices cemented together, providing excellent chromatic aberration correction capabilities. The selection of its focal length range helps to further optimize the imaging quality of the projection lens module, reducing image blurring and color distortion caused by chromatic aberration. The cemented doublet lens design allows the lens to maintain good imaging performance over a wider wavelength range.

[0167] The effective focal length range of the cemented triplicate lens (F'') is -80mm ≤ F'' ≤ -55mm. The cemented triplicate lens is composed of three lenses with different refractive indices cemented together, providing stronger aberration correction capabilities. Its larger negative focal length design helps to expand the projection range of the projection lens module, enabling short-throw projection. Simultaneously, the structure of the cemented triplicate lens also allows it to more effectively correct advanced aberrations (such as spherical aberration and coma), improving image quality.

[0168] The effective focal length range of the tenth lens (F10) is 9mm ≤ F10 ≤ 14mm. As the last lens in the projection lens module, the positive focal length design of the tenth lens 10 helps to form a high-quality image. It can not only further correct aberrations and distortions generated during light propagation, but also ensure that the light can be accurately focused on the imaging surface to form a clear and detailed image.

[0169] By precisely defining the effective focal length range of each lens in the projection lens module, this application achieves precise control and focusing of light. The combination of lenses with different focal lengths not only optimizes the optical path design and improves image quality, but also enables a compact and miniaturized lens design.

[0170] In some examples of this application, the second lens 2 to the ninth lens 9 are glass spherical lenses.

[0171] In the example provided in this application, the second lens 2 to the ninth lens 9 are all glass spherical mirrors, mainly due to a combination of optical performance and manufacturing cost considerations. Specifically, glass spherical mirrors can meet the high imaging quality requirements of projection lenses, while their manufacturing cost is relatively low, which helps to reduce the overall production cost of the lens.

[0172] Glass spherical mirrors possess excellent optical properties, reducing light scattering and absorption, and improving image clarity and contrast. The manufacturing cost of glass spherical mirrors is relatively low; therefore, choosing them as the material for lenses 2 through 9 helps reduce the production cost of projection lenses.

[0173] Furthermore, glass materials possess high thermal and chemical stability, enabling them to maintain stable optical performance under diverse environmental conditions. This contributes to enhanced stability of the entire projection system, improving product reliability and lifespan. Spherical mirrors also feature a relatively simple design, facilitating integration with other optical components.

[0174] In some examples of this application, the focal length of the projection lens module is 2.83mm, the projection ratio TR is 0.5, the relative aperture is 1 / 1.699, the offset is 140%, the pixel size is 5.4μm, the field of view is 55°~59°, the image plane size is 8.5mm~9.1mm, and the operating wavelength is 455nm~630nm.

[0175] Focal length is one of the most fundamental parameters in lens design, determining the lens's ability to converge light. The projection lens module of this application has a focal length of 2.83mm, which is a short-throw design suitable for short-distance projection scenarios. This short-throw design allows the projector to project a larger image at a closer distance, thus saving space and improving ease of use.

[0176] The throw ratio refers to the ratio of projection distance to screen width. The projection lens module of this application has a throw ratio of 0.5, meaning that at the same projection distance, the lens can project a wider screen. This feature makes the lens particularly suitable for environments with limited space, such as family living rooms and small conference rooms.

[0177] The relative aperture reflects the light-gathering capability of a lens. The projection lens module of this application has a relative aperture of 1 / 1.699, indicating that the projection lens module has a large entrance pupil diameter, which can receive more light, thereby improving the brightness and contrast of the image.

[0178] Offset refers to the percentage of the vertical distance from the bottom edge of the projected image to the bottom of the projector to the distance from the projector lens to the projected image. The projection lens module offset of this application is 140%, which means that the projected image can be further away from the projector body, reducing the shadow problem caused by the projector body and improving the viewing experience.

[0179] The projection lens module of this application is compatible with a pixel size of 5.4μm, which helps maintain image clarity and detail at high resolution. The projection lens module of this application has a field of view of 55°~59°, and this wider field of view allows the lens to capture a broader range of scenes, making it suitable for large-screen projection and wide-format displays. The projection lens module of this application is compatible with an image plane size of 8.5mm~9.1mm, which helps ensure that the image can be projected onto the screen completely and clearly.

[0180] The projection lens module of this application operates in the wavelength range of 455nm~630nm, covering most of the visible light range, and is suitable for color projection and high-definition video playback.

[0181] The projection lens module of this application achieves excellent optical performance, including short throw, large throw ratio, high brightness, and wide field of view. These performance characteristics make the lens module particularly suitable for short-distance projection needs in scenarios such as modern home theaters and small conference rooms. Furthermore, through optimized lens structure design and material selection, the projection lens module also achieves a compact and lightweight design, improving the product's portability and market competitiveness.

[0182] According to another embodiment of this application, a projection device is provided, the projection device including a housing and a projection lens module as described above.

[0183] The specific implementation of the projection device in this application can refer to the various embodiments of the projection lens module described above. Therefore, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, and will not be described in detail here.

[0184] The projection lens module of this application will be described below through Examples 1 to 5.

[0185] Example 1 See Figure 6 The projection lens module provided in Embodiment 1 includes a projection lens, a glass plate 14, and a display unit 13 arranged sequentially along the same optical axis; wherein, the display unit 13 is used to provide projection imaging light to the projection lens, and the projection lens is used to project imaging onto the light emitted by the display unit 13. The projection lens includes a first lens group, a second lens group, and an aperture 11 arranged along the same optical axis; The first lens group includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, and a cemented doublet lens arranged sequentially along the optical axis. The cemented doublet lens is composed of a fifth lens 5 and a sixth lens 6 cemented together. The first lens 1 is a plastic aspherical lens with negative optical power, the second lens 2 has negative optical power, the third lens 3 has negative optical power, the fourth lens 4 has positive optical power, and the cemented doublet lens has positive optical power. The second lens group includes a cemented triplet lens and a tenth lens 10 arranged sequentially along the optical axis. The cemented triplet lens is composed of a seventh lens 7, an eighth lens 8, and a ninth lens 9 cemented together, and the cemented triplet lens has negative optical power. The tenth lens 10 is a glass aspherical lens and has positive optical power. The second lens 2 to the ninth lens 9 are all glass spherical mirrors; The aperture 11 is located between the cemented doublet lens and the cemented triplet lens; The projection lens also includes a prism 12, which is disposed between the tenth lens 10 and the glass plate 14.

[0186] See Table 1, which shows... Figure 6 Some optical parameters of the provided projection lens module.

[0187] Table 1

[0188] Figure 6 Please refer to Table 2 for the aspherical parameters of the projection lens module shown.

[0189] Table 2

[0190] Example 2 See Figure 7The projection lens module provided in Embodiment 2 includes a projection lens, a glass plate 14, and a display unit 13 arranged sequentially along the same optical axis; wherein, the display unit 13 is used to provide projection imaging light to the projection lens, and the projection lens is used to project imaging onto the light emitted by the display unit 13. The projection lens includes a first lens group, a second lens group, and an aperture 11 arranged along the same optical axis; The first lens group includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, and a cemented doublet lens arranged sequentially along the optical axis. The cemented doublet lens is composed of a fifth lens 5 and a sixth lens 6 cemented together. The first lens 1 is a plastic aspherical lens with negative optical power, the second lens 2 has negative optical power, the third lens 3 has negative optical power, the fourth lens 4 has positive optical power, and the cemented doublet lens has positive optical power. The second lens group includes a cemented triplet lens and a tenth lens 10 arranged sequentially along the optical axis. The cemented triplet lens is composed of a seventh lens 7, an eighth lens 8, and a ninth lens 9 cemented together, and the cemented triplet lens has negative optical power. The tenth lens 10 is a glass aspherical lens and has positive optical power. The second lens 2 to the ninth lens 9 are all glass spherical mirrors; The aperture 11 is located between the cemented doublet lens and the cemented triplet lens; The projection lens also includes a prism 12, which is disposed between the tenth lens 10 and the glass plate 14.

[0191] See Figure 7 , Figure 7 Please refer to Table 3 below for some optical parameters of the projection lens module shown.

[0192] Table 3

[0193] Please refer to Table 4 for the aspherical parameters in the projection lens module provided in Example 2.

[0194] Table 4

[0195] Example 3 See Figure 8 The projection lens module provided in Embodiment 3 includes a projection lens, a glass plate 14, and a display unit 13 arranged sequentially along the same optical axis; wherein, the display unit 13 is used to provide projection imaging light to the projection lens, and the projection lens is used to project imaging onto the light emitted by the display unit 13. The projection lens includes a first lens group, a second lens group, and an aperture 11 arranged along the same optical axis; The first lens group includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, and a cemented doublet lens arranged sequentially along the optical axis. The cemented doublet lens is composed of a fifth lens 5 and a sixth lens 6 cemented together. The first lens 1 is a plastic aspherical lens with negative optical power, the second lens 2 has negative optical power, the third lens 3 has negative optical power, the fourth lens 4 has positive optical power, and the cemented doublet lens has positive optical power. The second lens group includes a cemented triplet lens and a tenth lens 10 arranged sequentially along the optical axis. The cemented triplet lens is composed of a seventh lens 7, an eighth lens 8, and a ninth lens 9 cemented together, and the cemented triplet lens has negative optical power. The tenth lens 10 is a glass aspherical lens and has positive optical power. The second lens 2 to the ninth lens 9 are all glass spherical mirrors; The aperture 11 is located between the cemented doublet lens and the cemented triplet lens; The projection lens also includes a prism 12, which is disposed between the tenth lens 10 and the glass plate 14.

[0196] See Figure 8 , Figure 8 Please refer to Table 5 below for some optical parameters of the projection lens module shown.

[0197] Table 5

[0198] Please refer to Table 6 for the aspherical parameters in the projection lens module provided in Example 3.

[0199] Table 6

[0200] Example 4 See Figure 9 The projection lens module provided in Embodiment 4 includes a projection lens, a glass plate 14, and a display unit 13 arranged sequentially along the same optical axis; wherein, the display unit 13 is used to provide projection imaging light to the projection lens, and the projection lens is used to project imaging onto the light emitted by the display unit 13. The projection lens includes a first lens group, a second lens group, and an aperture 11 arranged along the same optical axis; The first lens group includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, and a cemented doublet lens arranged sequentially along the optical axis. The cemented doublet lens is composed of a fifth lens 5 and a sixth lens 6 cemented together. The first lens 1 is a plastic aspherical lens with negative optical power, the second lens 2 has negative optical power, the third lens 3 has negative optical power, the fourth lens 4 has positive optical power, and the cemented doublet lens has positive optical power. The second lens group includes a cemented triplet lens and a tenth lens 10 arranged sequentially along the optical axis. The cemented triplet lens is composed of a seventh lens 7, an eighth lens 8, and a ninth lens 9 cemented together, and the cemented triplet lens has negative optical power. The tenth lens 10 is a glass aspherical lens and has positive optical power. The second lens 2 to the ninth lens 9 are all glass spherical mirrors; The aperture 11 is located between the cemented doublet lens and the cemented triplet lens; The projection lens also includes a prism 12, which is disposed between the tenth lens 10 and the glass plate 14.

[0201] See Figure 9 , Figure 9 Please refer to Table 7 below for some optical parameters of the projection lens module shown.

[0202] Table 7

[0203] Please refer to Table 8 for the aspherical parameters in the projection lens module provided in Example 4.

[0204] Table 8

[0205] Example 5 See Figure 10 The projection lens module provided in Embodiment 5 includes a projection lens, a glass plate 14, and a display unit 13 arranged sequentially along the same optical axis; wherein, the display unit 13 is used to provide projection imaging light to the projection lens, and the projection lens is used to project imaging onto the light emitted by the display unit 13. The projection lens includes a first lens group, a second lens group, and an aperture 11 arranged along the same optical axis; The first lens group includes a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, and a cemented doublet lens arranged sequentially along the optical axis. The cemented doublet lens is composed of a fifth lens 5 and a sixth lens 6 cemented together. The first lens 1 is a plastic aspherical lens with negative optical power, the second lens 2 has negative optical power, the third lens 3 has negative optical power, the fourth lens 4 has positive optical power, and the cemented doublet lens has positive optical power. The second lens group includes a cemented triplet lens and a tenth lens 10 arranged sequentially along the optical axis. The cemented triplet lens is composed of a seventh lens 7, an eighth lens 8, and a ninth lens 9 cemented together, and the cemented triplet lens has negative optical power. The tenth lens 10 is a glass aspherical lens and has positive optical power. The second lens 2 to the ninth lens 9 are all glass spherical mirrors; The aperture 11 is located between the cemented doublet lens and the cemented triplet lens; The projection lens also includes a prism 12, which is disposed between the tenth lens 10 and the glass plate 14.

[0206] See Figure 10 , Figure 10 Please refer to Table 9 below for some optical parameters of the projection lens module shown.

[0207] Table 9

[0208] Please refer to Table 10 for the aspherical parameters in the projection lens module provided in Example 5.

[0209] Table 10

[0210] The optical performance of the projection lens modules provided in Embodiments 1 to 5 above is as follows: See Figure 11 , Figure 11 The distortion diagram shows that the absolute value of the distortion is less than 3.5%. This means that the projection lens module can maintain good image shape and proportion during imaging, avoiding image distortion and deformation. This excellent distortion performance is particularly important for projection displays, ensuring that the image viewed by the audience is more realistic and natural.

[0211] See Figure 12 , Figure 12 The MTF diagram is for the projection lens module. The MTF is >0.55 at 93 lp / mm.

[0212] from Figure 12 As can be seen, the MTF is greater than 0.55 at a spatial frequency of 93 lp / mm (line pairs / mm), indicating that the projection lens module can still maintain good image quality at high resolution and can clearly reproduce the details of objects. This excellent MTF performance is crucial for projection displays, ensuring that the image viewed by the audience is more delicate and clear.

[0213] The above analysis of distortion and MTF performance demonstrates that the projection lens module of this application exhibits excellent optical performance. An absolute distortion value of less than 3.5% ensures the realism and naturalness of the image; an MTF greater than 0.55 at 93 lp / mm guarantees the lens's sharpness and detail resolution at high resolution. These superior optical properties make this lens module particularly suitable for applications requiring high image quality, such as home theaters and conference room projections.

[0214] The above embodiments mainly describe the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. For the sake of brevity, they will not be elaborated here.

[0215] While specific embodiments of this application have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of this application. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of this application. The scope of this application is defined by the appended claims.

Claims

1. A projection lens module, characterized in that, Comprising two lens groups and a stop (11) arranged along the same optical axis, wherein the two lens groups are a first lens group and a second lens group respectively: The first lens group consists of a first lens (1), a second lens (2), a third lens (3), a fourth lens (4) and a cemented doublet arranged sequentially along the optical axis, the cemented doublet is formed by cementing a fifth lens (5) and a sixth lens (6), wherein: the first lens (1), the second lens (2) and the third lens (3) all have negative optical power, the fourth lens (4) and the cemented doublet both have positive optical power, the fifth lens (5) has positive optical power, and the sixth lens (6) has negative optical power; The second lens group consists of a cemented triplet and a tenth lens (10) arranged along the optical axis, the cemented triplet is formed by sequentially cementing a seventh lens (7), an eighth lens (8) and a ninth lens (9), wherein: the seventh lens (7) and the ninth lens (9) both have positive optical power, the eighth lens (8) has negative optical power, the cemented triplet has negative optical power, and the tenth lens (10) has positive optical power; The stop (11) is located between the cemented doublet and the cemented triplet, the distance between the stop (11) and the cemented doublet is L1, the distance between the stop (11) and the cemented triplet is L2, and L1 and L2 satisfy: 3.3<L1 / L2<4; The first lens (1) is a plastic aspheric lens, and the tenth lens (10) is a glass aspheric lens.

2. The projection lens module according to claim 1, characterized in that, The central thickness T' of the cemented triplet satisfies 8.5%≤T' / TTL≤10%; wherein TTL is the total optical length of the projection lens module.

3. The projection lens module according to claim 1 or 2, characterized in that, The refractive index of either of the seventh lens (7) and the ninth lens (9) is lower than the refractive index of the eighth lens (8).

4. The projection lens module according to claim 3, characterized in that, In the cemented doublet, the refractive index of the fifth lens (5) is higher than the refractive index of the sixth lens (6).

5. The projection lens module according to claim 4, characterized in that, The refractive index of the fifth lens (5) is N5, the refractive index of the sixth lens (6) is N6, and N5 and N6 satisfy: 1.03<N5 / N6<1.

1.

6. The projection lens module according to claim 1, characterized in that, The first lens group satisfies: 0.95<T3 / (T1+T2)<1.3, wherein: T1 is the central thickness of the first lens (1), T2 is the central thickness of the second lens (2), and T3 is the central thickness of the third lens (3).

7. The projection lens module according to claim 1 or 6, characterized in that, The central thickness T1 of the first lens (1) satisfies 3.3%≤T1 / TTL≤3.7%; The central thickness T2 of the second lens (2) satisfies 1.5%≤T2 / TTL≤1.8%; Wherein, TTL is the total optical length of the projection lens module.

8. The projection lens module according to claim 7, characterized in that, The sagitta of the surface of the second lens (2) on the side away from the stop (11) at the maximum aperture is S1, the sagitta of the surface on the side close to the stop (11) at the maximum aperture is S2, and the following condition is satisfied: 3.5<S2 / S1<4.

5.

9. The projection lens module according to claim 8, characterized in that, For a surface of the second lens (2) on a side away from the diaphragm (11), an included angle between a tangent at the maximum aperture and the optical axis is A1; for a surface of the second lens (2) on a side close to the diaphragm (11), an included angle between a tangent at the maximum aperture and the optical axis is A2, and the following conditions are satisfied: 40°<A1-A2<50°, and 1.8<A1 / A2<2.

3.

10. The projection lens module according to claim 1 or 6, characterized in that, For a surface of the third lens (3) on a side away from the diaphragm (11), an included angle between a tangent at the maximum aperture and the optical axis is A3; for a surface of the third lens (3) on a side close to the diaphragm (11), an included angle between a tangent at the maximum aperture and the optical axis is A4, and the following conditions are satisfied: 40°<A3-A4<60°, and 1.6<A3 / A4<2.

1.

11. The projection lens module according to claim 4, characterized in that, The projection lens module further comprises a prism (12), a glass plate (14) and a display unit (13) which are arranged in sequence on a side of the tenth lens (10) away from the diaphragm (11); A ratio of a total optical length TTL of the projection lens module to a maximum aperture D1 of a lens in the projection lens satisfies: 1.5<TTL / D1<1.

9.

12. The projection lens module according to claim 11, characterized in that, The effective focal lengths of the lenses in the projection lens are respectively: An effective focal length of the first lens (1) is F1, which satisfies -32mm≤F1≤-24mm; An effective focal length of the second lens (2) is F2, which satisfies -19mm≤F2≤-14mm; An effective focal length of the third lens (3) is F3, which satisfies -19mm≤F3≤-14mm; An effective focal length of the fourth lens (4) is F4, which satisfies 25mm≤F4≤36mm; An effective focal length of the doublet lens is F', which satisfies 17mm≤F'≤25mm; An effective focal length of the triplet lens is F'', which satisfies -80mm≤F''≤-55mm; An effective focal length of the tenth lens (10) is F10, which satisfies 9mm≤F10≤14mm; The second lens (2) to the ninth lens (9) are glass spherical lenses.

13. The projection lens module according to claim 12, characterized in that, The projection lens module has a focal length of 2.83mm, a projection ratio TR of 0.5, a relative aperture of 1 / 1.699, an Offset of 140%, a pixel size of 5.4μm, a field angle of 55°~59°, an image surface size of 8.5mm~9.1mm, and a working wavelength band of 455nm~630nm.

14. A projection device, characterized in that, Comprising: an outer housing; and the projection lens module according to any one of claims 1 to 13.

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