Projection lens module and micro-projection device

Abstract

Embodiments of the present application provide a projection lens module and a micro-projection device; the projection lens module sequentially includes a first lens group, a diaphragm, and a second lens group along the optical axis from the object side to the image side; the first lens group includes a first doublet lens and a third lens arranged along the optical axis, the first doublet lens has a positive optical power, the third lens has a negative optical power, and the first doublet lens can move along the optical axis to adjust the focal length of the projection lens module; the second lens group includes a second doublet lens, a third doublet lens, and an eighth lens arranged in sequence along the optical axis, the second doublet lens, the third doublet lens, and the eighth lens all have positive optical powers, and the third doublet lens can move along the optical axis to compensate for the image plane displacement caused by the movement of the third lens, so as to keep the imaging clear; the diaphragm is located between the third lens and the second doublet lens.

Description

Technical Field

[0001] Embodiments of the present application relate to the field of projection optical display technology. More specifically, embodiments of the present application relate to a projection lens module and a micro-projection device. Background Art

[0002] As a device commonly used in commercial displays and advertising, the performance improvement of commercial micro-projectors has always been the focus of the industry. In the design of projectors, focal length and field of view are two important parameters. Traditional commercial micro-projectors usually adopt a design with a long focal length and a small field of view. This design meets the projection requirements in certain scenarios to a certain extent, but also brings some limitations.

[0003] First of all, it is difficult to achieve both a large projection ratio and variable focal length in the design of the projection lenses of existing micro-projectors. A large projection ratio means that the projection lens can project a larger image at a shorter projection distance, and variable focal length provides greater flexibility, enabling the projection lens to adapt to different projection distances. However, the projection lenses in the prior art often fail to achieve ideal effects in both aspects.

[0004] Secondly, the volume of existing projection lenses is large, and the maximum effective aperture exceeds 33 mm. This is a significant drawback for commercial micro-projectors because one of the design goals of projectors is to pursue compactness. The large volume increases the weight and occupied space of the device, and also raises the production cost.

[0005] In addition, insufficient chromatic aberration and aberration correction is another problem existing in existing projection lenses. These optical defects will affect the clarity and color reproduction of the projection image, reduce the imaging quality, and thus affect the user's visual experience. Summary of the Invention

[0006] The purpose of the present application is to provide a new technical solution for a projection lens module and a micro-projection device.

[0007] In a first aspect, embodiments of the present application provide a projection lens module. The projection lens module sequentially includes a first lens group, a diaphragm, and a second lens group along the optical axis from the image side to the object side;

[0008] The first lens group includes a first doublet lens and a third lens arranged along the optical axis. The first doublet lens has a positive optical power, and the third lens has a negative optical power;

[0009] The second lens group includes a second doublet lens, a third doublet lens, and an eighth lens arranged in sequence along the optical axis. The second doublet lens, the third doublet lens, and the eighth lens all have positive optical powers;

[0010] The diaphragm is located between the third lens and the second doublet lens;

[0011] Wherein, the first doublet lens and the third doublet lens can move synchronously along the optical axis. Through their coordinated displacement:

[0012] The movement of the first doublet lens is used to adjust the focal length of the projection lens module;

[0013] The movement of the third doublet lens is used to compensate for the image plane displacement caused by the change in focal length.

[0014] Optionally, the central thickness T3 of the third lens and the optical total length TTL of the projection lens module satisfy: 8% < T3 / TTL < 11.5%.

[0015] Optionally, the sagittal height at the maximum aperture of the image side of the third lens is S1, the sagittal height at the maximum aperture of the object side is S2, and the ratio of S1 to S2 satisfies: 1.2 < S1 / S2 < 1.8.

[0016] Optionally, the angle between the tangent line at the maximum aperture of the object side of the third lens and the optical axis is A1, the angle between the tangent line at the maximum aperture of the image side and the optical axis is A2, and A1 and A2 satisfy: 42° < (A1 + A2) / 2 < 49°, and 0.85 < A1 / A2 < 1.05.

[0017] Optionally, the sum T' of the central thicknesses of the first doublet lens, the second doublet lens, and the third doublet lens and the optical total length TTL of the projection lens module satisfy: 16% < T' / TTL < 33%.

[0018] Optionally, the central thickness T1 of the first doublet lens and the optical total length TTL of the projection lens module satisfy: 7% < T1' / TTL < 14%.

[0019] Optionally, the first doublet lens is composed of a first lens and a second lens glued together. Wherein, the first lens has a positive optical power, the second lens has a negative optical power, and the refractive index N1 of the first lens is lower than the refractive index N2 of the second lens.

[0020] Optionally, the first lens group satisfies: 10 < (T3 + T1) / T2 < 14; where T1 is the central thickness of the first lens, T2 is the central thickness of the second lens, and T3 is the central thickness of the third lens.

[0021] Optionally, the second doublet lens is composed of a fourth lens and a fifth lens glued together, where the fourth lens has a positive optical power, the fifth lens has a negative optical power, and the refractive index N4 of the fourth lens is lower than the refractive index N5 of the fifth lens;

[0022] The third doublet lens is composed of a sixth lens and a seventh lens glued together, where the sixth lens has a negative optical power, the seventh lens has a positive optical power, and the refractive index N7 of the seventh lens is lower than the refractive index N6 of the sixth lens.

[0023] Optionally, the following condition is satisfied among the fourth lens, the fifth lens, the sixth lens and the seventh lens: 3 < (T4 + T7) / (T5 + T6) < 4.8; where T4 is the central thickness of the fourth lens, T5 is the central thickness of the fifth lens, T6 is the central thickness of the sixth lens, and T7 is the central thickness of the seventh lens.

[0024] Optionally, the effective focal lengths of the lenses in the projection lens module satisfy:

[0025] The effective focal length of the first doublet lens is F', and 70 mm ≤ F' ≤ 90 mm;

[0026] The effective focal length of the third lens is F3, and -20 mm ≤ F3 ≤ -13 mm;

[0027] The effective focal length of the second doublet lens is F'', and 600 mm ≤ F'' ≤ 800 mm;

[0028] The effective focal length of the third doublet lens is F''', and 25 mm ≤ F''' ≤ 37 mm;

[0029] The effective focal length of the eighth lens is F8, and 52 mm ≤ F8 ≤ 74 mm;

[0030] Each lens in the projection lens module is a glass spherical lens.

[0031] Optionally, the projection lens module further includes a galvanometer, a prism, a glass plate and a display unit that are sequentially arranged on the object side of the eighth lens;

[0032] 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 module satisfies: 1.7 < TTL / D1 < 2.7.

[0033] Optionally, the total optical length TTL of the projection lens module is 59 mm < TTL < 85 mm, and the maximum effective aperture is 33 mm.

[0034] Optionally, the optical parameters of the projection lens module include: focal length from 21 mm to 32 mm, projection ratio TR from 4 to 6, relative aperture of 1 / 1.73, Offset of 0%, pixel size of 5.4 μm, field of view angle from 5.2° to 8.1°, image plane size from 5.5 mm to 6.5 mm, and working wavelength range from 455 nm to 630 nm.

[0035] In a second aspect, an embodiment of the present application provides a micro-projection device, which includes:

[0036] a housing; and

[0037] the projection lens module as described in the second aspect.

[0038] The beneficial effects of the present application are as follows:

[0039] For the projection lens module provided by the embodiment of the present application, the focal length of the entire projection lens module can be adjusted by moving the first doublet lens, so that the size of the projection screen can be adjusted within a focal length range of, for example, 21 mm to 32 mm, thereby meeting the projection requirements in different scenarios. At the same time, the synchronous movement of the third doublet lens can be used to compensate for the image plane displacement caused by the change in the focal length of the first doublet lens, ensuring the stability of the imaging plane during the zoom process and avoiding the occurrence of image blurring.

[0040] The combination design of the optical power of the first lens group, "a positive optical power doublet lens paired with a negative optical power single lens", and the second lens group with all positive optical powers in the embodiment of the present application can effectively correct aberration problems such as field curvature and spherical aberration, laying a foundation for high-quality imaging. The collaborative work between the three positive optical power elements in the second lens group and the movable third doublet lens further corrects the chromatic aberration problems that may occur during the zoom process, enabling the projection lens module to maintain excellent optical performance throughout the zoom range and ensuring the clarity of the projection screen. In addition, the reasonable setting of the aperture position not only optimizes the optical performance of the projection lens module but also improves the structural compactness of the projection lens module.

[0041] In summary, the projection lens module provided by the embodiment of the present application not only realizes the adjustment of the focal length but also ensures excellent optical performance and structural compactness, bringing a good visual experience to users.

[0042] Other features and advantages of the present specification will become clear through the following detailed description of the exemplary embodiments of the present specification with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The drawings incorporated in and constituting a part of this specification illustrate embodiments of the present specification and, together with the description, are used to explain the principles of the present specification.

[0044] Figure 1 Schematic diagram of the optical architecture of the projection lens module provided by the embodiment of the present application;

[0045] Figure 2 Partial structural schematic diagram of the third lens of the projection lens provided by the embodiment of the present application;

[0046] Figure 3 For Figure 1 Distortion diagram of the projection lens module provided;

[0047] Figure 4 For Figure 1 MTF diagram of the projection lens module provided;

[0048] Figure 5 For Figure 1 Dot array diagram of the projection lens module provided;

[0049] Figure 6 For Figure 1 Perpendicular chromatic aberration diagram of the projection lens module provided;

[0050] Figure 7 Structure and optical path diagram of the projection lens module provided by Embodiment 1 of the present application;

[0051] Figure 8 For Figure 7 Dot array diagram of the projection lens module provided;

[0052] Figure 9 For Figure 7 MTF diagram of the projection lens module provided;

[0053] Figure 10 For Figure 7 Field curvature and distortion diagram of the projection lens module provided;

[0054] Figure 11 For Figure 7 Perpendicular chromatic aberration diagram of the projection lens module provided;

[0055] Figure 12 Structure and optical path diagram of the projection lens module provided by Embodiment 2 of the present application;

[0056] Figure 13 For Figure 12 Dot array diagram of the projection lens module provided;

[0057] Figure 14 For Figure 12 MTF diagram of the projection lens module provided;

[0058] Figure 15 For Figure 12 Field curvature and distortion diagram of the projection lens module provided;

[0059] Figure 16 For Figure 12 the lateral chromatic aberration diagram of the provided projection lens module;

[0060] Figure 17 the structure and optical path diagram of the projection lens module provided in Embodiment 3 of the present application;

[0061] Figure 18 For Figure 17 the dot array diagram of the provided projection lens module;

[0062] Figure 19 For Figure 17 the MTF diagram of the provided projection lens module;

[0063] Figure 20 For Figure 17 the field curvature and distortion diagram of the provided projection lens module;

[0064] Figure 21 For Figure 17 the lateral chromatic aberration diagram of the provided projection lens module;

[0065] Figure 22 the corresponding relationship diagram between the focal length of the projection lens module provided in the embodiments of the present application and the air spaces A, B, and C.

[0066] Description of reference numerals:

[0067] 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. Diaphragm; 10. Galvanometer; 11. Prism; 12. Display unit; 13. Glass plate. Detailed implementation manners

[0068] Now, various exemplary embodiments of the present application will be described in detail with reference to the accompanying drawings. It should be noted that: Unless otherwise specifically stated, the relative arrangements of components and steps set forth in these embodiments, numerical expressions, and numerical values do not limit the scope of the present application.

[0069] The following description of at least one exemplary embodiment is actually merely illustrative and in no way restricts the present application, its application, or its use.

[0070] Technologies and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, such technologies and devices should be regarded as part of the specification.

[0071] In all the examples shown and discussed herein, any specific values should be construed as merely exemplary and not as a limitation. Thus, other examples of the exemplary embodiments may have different values.

[0072] It should be noted that like reference numerals and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof in subsequent figures is not required.

[0073] The projection lens module and the micro - projection device provided by the embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0074] According to an embodiment of the present application, a projection lens module is provided. Refer to Figure 1 , the projection lens module sequentially includes a first lens group, a diaphragm 9, and a second lens group along the optical axis from the image side to the object side. The first lens group includes a first doublet lens and a third lens 3 arranged along the optical axis. Among them, the first doublet lens has a positive optical power, and the third lens 3 has a negative optical power. The second lens group includes a second doublet lens, a third doublet lens, and an eighth lens 8 arranged in sequence along the optical axis. Among them, the second doublet lens, the third doublet lens, and the eighth lens 8 all have positive optical powers. The diaphragm 9 is located between the third lens 3 and the second doublet lens. In the projection lens module of the embodiment of the present application, refer to Figure 7 , Figure 12 and Figure 17 , the first doublet lens and the third doublet lens can move synchronously along the optical axis. Through their coordinated displacement: the movement of the first doublet lens is used to adjust the focal length of the projection lens module; the movement of the third doublet lens is used to compensate for the image plane displacement caused by the change in focal length.

[0075] That is to say, the projection lens module provided by the embodiment of the present application is a variable - focal - length optical design and can achieve a focusing effect.

[0076] The projection lens module provided by the embodiment of the present application, refer to Figure 1 , its main components include a projection lens and a display unit 12. Among them, the projection lens includes the above - mentioned first lens group, second lens group, and a diaphragm 9 located between the two lens groups (the position of the diaphragm 9 is fixed, that is, the air gaps between the diaphragm 9 and the lenses on both sides are fixed). The projection lens is located on the light - emitting optical path of the display unit 12. The projection lens is responsible for receiving the light emitted from the display unit 12 (these lights are specifically used for projection display) and performing processing such as modulation and focusing on these lights. Through this series of optical effects, the light emitted by the display unit 12 can be guided and projected onto the imaging plane, and finally a clear projection image is presented.

[0077] See also Figure 1 The projection lens module provided by the embodiment of the present application includes a first lens group, a second lens group and an aperture 9. Figure The second lens group (located relatively to the left in the middle) is further away from the display unit 12 in the projection lens module than the second lens group. Figure 1 The aperture 9 is located between the first lens group and the second lens group, and is mainly used to optimize the transmission path of light to further improve the imaging effect.

[0078] It should be noted that, see Figure 1 In the optical design of this application, the side where the display unit 12 is located is defined as the object side, and the side away from the display unit 12 is defined as the image side. That is, the first lens group is close to the image side, and the second lens group is close to the object side.

[0079] The first lens assembly provided in the embodiments of the present application is described in detail as follows.

[0080] The first lens assembly provided in the embodiments of the present application is one component of the entire projection lens module (or projection lens). The first lens assembly is primarily composed of a first doublet lens and a single third lens 3, each of which plays an important role in the entire projection lens module.

[0081] Specifically, in the first lens assembly, the first doublet lens is designed to be composed of two lenses (e.g., first lens 1 and second lens 2) bonded together to form a single, integrated optical element. Furthermore, the first doublet lens is designed to have positive optical power (i.e., a positive lens), primarily focusing light and enhancing the light-collecting capability of the entire projection lens module. The third lens 3 has a different optical power from the first doublet lens; it is designed to have negative optical power and diverge light.

[0082] Specifically, within the first lens assembly, the first doublet lens is designed to move along the optical axis to vary the air gap A between it and the third lens 3. As the first doublet lens moves along the optical axis toward or away from the third lens 3, the focal length of the projection lens module can be adjusted. In other words, this design allows the focal length of the projection lens module to be varied by adjusting the position of the first doublet lens on the optical axis, thereby achieving a zoom function.

[0083] In one example, see Figure 7, the first doublet lens moves along the optical axis to a position away from the third lens 3. At this time, the air gap A between the first doublet lens and the third lens 3 is relatively large, and the focal length of the projection lens module is about 32.3 mm. In this example, the projection lens module is in the telephoto state.

[0084] In another example, referring to Figure 17 , the first doublet lens moves along the optical axis to a position close to the third lens 3. At this time, the air gap A between the first doublet lens and the third lens 3 significantly decreases (compared to Figure 7 ), and the focal length of the projection lens module becomes about 21.3 mm. In this example, the projection lens module is in the wide-angle state.

[0085] In yet another example, referring to Figure 12 , the first doublet lens moves along the optical axis to a position different from the above two examples. At this time, the air gap A between the first doublet lens and the third lens 3 is smaller than the air gap A shown in Figure 7 , and larger than the air gap A shown in Figure 17 . In this example, the projection lens module is in the mid-tele state.

[0086] The embodiments of the present application provide a projection lens module. By moving the first doublet lens along the optical axis, the adjustment of the focal length of the entire projection lens module is achieved. For example, the projection lens module provided by the embodiments of the present application can cover a focal length range of 21 mm to 32 mm, referring to Figure 22 .

[0087] It should be noted that during the zooming process, the movement of a single lens (even a cemented lens) is difficult to simultaneously meet the requirements of the entire module's focal length change and image plane stability. Therefore, a cooperative movement mechanism of the first doublet lens and the third doublet lens is adopted in the present application. In short, when the first doublet lens moves along the optical axis to adjust the focal length of the module, the synchronous movement of the third doublet lens can compensate for the image plane displacement caused by the focal length change. The way of multiple lenses working together in the embodiments of the present application ensures the stability of the imaging plane during the zooming process, and clear imaging can be maintained even when the focal length changes. Since the synchronously moving third doublet lens is located in the second lens group, the third doublet lens will be specifically described in the description part of the second lens group.

[0088] The second lens group provided in the embodiments of the present application is specifically described as follows.

[0089] In the embodiment of the present application, the second lens group is another component of the projection lens module (or projection lens), and it also plays an important optical role in the imaging process. The second lens group mainly consists of a second doublet lens, a third doublet lens, and a separate eighth lens 8, and each of these optical lenses undertakes a specific optical function. In the second lens group, all the lenses have positive optical power, and they jointly converge light to form a clear image on the imaging surface.

[0090] Specifically, in the second lens group: The second doublet lens is composed of two lenses (such as the fourth lens 4 and the fifth lens 5) combined through a gluing process to form an integral optical element. The second doublet lens is designed to have positive optical power, and it can effectively converge light to further enhance the focusing effect of light. The third doublet lens is also composed of two lenses (such as the sixth lens 6 and the seventh lens 7) glued together. The third doublet lens is also designed to have positive optical power. Moreover, the third doublet lens is designed to be able to move synchronously with the first doublet lens along the optical axis.

[0091] It should be noted that during the zooming process of the projection lens module, the change in focal length often leads to the displacement of the image plane, affecting the imaging quality. In the embodiment of the present application, by synchronously moving the third doublet lens, the image plane displacement caused by the change in the focal length of the first doublet lens is effectively compensated. This design ensures the stability of the imaging surface during the zooming process, avoids image blurring, and guarantees a high-quality projection effect.

[0092] In the second lens group, the eighth lens 8 is designed as a positive lens, and it works in cooperation with other lenses (especially the second doublet lens and the third doublet lens in the same lens group). Specifically, the main functions of the eighth lens 8 are reflected in the following two aspects:

[0093] First aspect: As a positive lens, the eighth lens 8 has the ability to converge light. It works in cooperation with the second doublet lens and the third doublet lens to enhance the light converging effect of the second lens group. This strengthening effect helps to ensure that light can be more accurately focused on the imaging surface, thereby improving the clarity of the projection image.

[0094] Second aspect: The positive optical power characteristic of the eighth lens 8 not only helps to converge light but also can correct aberrations to a certain extent, such as spherical aberration and chromatic aberration. By interacting with the second doublet lens and the third doublet lens in the same lens group, the eighth lens 8 can further optimize the imaging quality and ensure the color reproduction of the projection image.

[0095] Based on the optical design of the eighth lens 8, it is possible to enable the projection lens module to maintain a high-quality imaging effect during the zooming process. In short, regardless of how the focal length of the projection lens module changes, the eighth lens 8 can accurately focus the light on the imaging surface, thereby forming a high-quality projection image.

[0096] Please continue to refer to Figure 1 , in the projection lens module, the aperture stop 9 is designed to be located between the third lens 3 and the second doublet lens. It is mainly used to limit the passing range of light and control the size of the imaging light beam, which helps to improve the imaging quality.

[0097] The projection lens module provided by the embodiment of the present application, refer to Figure 7 , Figure 12 and Figure 17 , in the first lens group, the first doublet lens can move along the optical axis direction to approach or move away from the third lens 3, which realizes the adjustment of the air gap A, and thus can realize the change of the focal length of the projection lens module. At the same time, the third doublet lens in the second lens group also has the ability to move along the optical axis, and it is designed to move synchronously with the first doublet lens. By synchronously adjusting the position of the third doublet lens on the optical axis, the air gap B between the third doublet lens and the second doublet lens, and the air gap C between the third doublet lens and the eighth lens 8 can be changed. This lens movement mechanism in the present application not only ensures the stability of the optical performance during the zooming process, but also effectively compensates for the image plane displacement caused by the change of the focal length, thereby maintaining the clarity and imaging quality of the projection image throughout the zoom range.

[0098] Please refer to Figure 22 , the focal length range of the projection lens module provided by the embodiment of the present application is, for example, 21.3 mm to 32.3 mm, and its zoom ratio is 1.5X.

[0099] The projection lens module provided by the embodiment of the present application can adjust the focal length of the entire projection lens module by moving the first doublet lens, so that the size of the projection image can be adjusted within the focal length range of, for example, 21 mm to 32 mm, thereby meeting the projection requirements in different scenarios. At the same time, the synchronous movement of the third doublet lens can be used to compensate for the image plane displacement caused by the change of the focal length of the first doublet lens, ensuring the stability of the imaging plane during the zooming process and avoiding the occurrence of image blurring.

[0100] In the embodiment of the present application, the optical power combination design of the first lens group, which is a "positive optical power doublet lens paired with a negative optical power single lens", and the second lens group with all positive optical powers can effectively correct aberration problems such as field curvature and spherical aberration, laying a foundation for high-quality imaging. The collaborative work between the three positive optical power elements in the second lens group and the movable third doublet lens further corrects the chromatic aberration problems that may occur during the zooming process, enabling the projection lens module to maintain excellent optical performance throughout the zoom range and ensuring the clarity of the projection image. In addition, the reasonable setting of the diaphragm position not only optimizes the optical performance of the projection lens module but also improves the structural compactness of the projection lens module.

[0101] In summary, the projection lens module provided by the embodiment of the present application not only realizes the adjustment of the focal length but also ensures excellent optical performance and structural compactness, bringing a good visual experience to users.

[0102] In addition, for the projection lens module provided by the embodiment of the present application, the projection lens only adopts an 8-lens design, as shown in Figure 1 , and through the reasonable setting of the diaphragm 9 and the lens arrangement order (such as reasonable optical power distribution), the compactness of the optical structure is achieved. This design enables the projection lens module of the embodiment of the present application to be applicable to application scenarios with limited space, such as commercial micro-projectors.

[0103] During the zooming process of the projection lens module provided by the embodiment of the present application, its projection ratio can be adjusted within the range of 4 to 6.

[0104] In some examples of the present application, as shown in Figure 1 , the third lens 3 is a lens with a relatively large thickness in the first lens group, that is, the third lens 3 is designed as a thick lens. The central thickness T3 of the third lens 3 and the overall optical length TTL of the projection lens module satisfy: 8% < T3 / TTL < 11.5%.

[0105] In the example provided by the present application, the third lens 3 is not only designed as a lens with a relatively large thickness in the first lens group, but also its central thickness T3 and the overall optical length TTL of the projection lens module are designed to satisfy a specific proportional relationship, that is, 8% < T3 / TTL < 11.5%. This optical design has obvious advantages in reducing the field curvature of the projection lens module, and the specific analysis is as follows.

[0106] Field Curvature is an aberration that needs to be controlled, otherwise it will affect the imaging quality.

[0107] In the projection lens module provided by the embodiments of the present application, the third lens 3, as one of the thick lenses, can provide better light modulation ability with its relatively large central thickness, which helps to correct field curvature. In this example provided by the present application, by further designing the ratio between the central thickness T3 of the third lens 3 and the TTL to be between 8% and 11.5%, the range of the central thickness of the third lens 3 can be better controlled, enabling it to have sufficient light modulation ability, effectively correcting the field curvature of the projection lens module, and thus improving the imaging quality of the entire projection lens module.

[0108] In this example provided by the present application, by reasonably controlling the central thickness T3 of the third lens 3, not only the field curvature is reduced, but also positive effects can be produced on other aberrations such as spherical aberration and chromatic aberration.

[0109] The third lens 3, as one of the main lenses in the first lens group, its fixed position and specific design (such as the thick lens design) play a role in stabilizing the optical performance during the zoom process.

[0110] As mentioned above, the design of the central thickness T3 of the third lens 3 helps to correct field curvature. During the zoom process, although the focal length is changing, the correction effect of the third lens 3 on field curvature still exists. This helps to ensure that the edges of the projection screen remain clear even at different focal lengths.

[0111] In the projection lens module provided by the embodiments of the present application, the third lens 3 also works together with other lenses, especially the first doublet lens and the third doublet lens, to correct aberrations jointly. Although it does not move during the zoom process, its inherent optical characteristics still have a positive impact on the correction of aberrations. This helps to improve the overall clarity and color reproduction of the projection screen.

[0112] In addition, the proportional relationship provided in this example of the present application well controls the central thickness of the third lens 3, making its central thickness appropriate and not affecting the volume and weight of the projection lens module.

[0113] In some examples of the present application, see Figure 1 , the sagittal height at the maximum aperture of the image side of the third lens 3 is S1, the sagittal height at the maximum aperture of the object side is S2, and the ratio of S1 to S2 satisfies: 1.2 < S1 / S2 < 1.8.

[0114] In the examples provided in this application, the third lens 3 is a negative lens, and the ratio between the sagittal height S1 of the image side (i.e., the side away from the display unit 12) and the sagittal height S2 of the object side (i.e., the side close to the display unit 12) of the third lens 3 is designed. This optical design reflects further control over the surface shape of the third lens 3, aiming to further optimize the overall performance of the projection lens module.

[0115] By adjusting the ratio range of the above-mentioned S1 and S2, characteristics such as the refraction of light by the third lens 3 can be controlled, thereby more effectively correcting aberrations, especially aberrations such as field curvature. These aberrations often lead to blurring or distortion of the image edges. By regulating the ratio range of S1 and S2, the third lens 3 can provide excellent aberration correction effects at different field angles, improving the overall clarity and detail expressiveness of the projection image.

[0116] By controlling the ratio range of S1 and S2 of the third lens 3, it can be ensured that the propagation path of light remains stable during the zoom process. This helps to reduce image blurring and distortion caused by changes in focal length, improving the stability and reliability during the zoom process. In addition, by regulating the ratio range of S1 and S2 of the third lens 3, while ensuring optical performance, the volume and weight of the entire projection lens module can be reduced.

[0117] In some examples of this application, refer to Figure 2 , the angle between the tangent line at the maximum aperture of the object side of the third lens 3 and the optical axis is A1, and the angle between the tangent line at the maximum aperture of its image side and the optical axis is A2, and A1 and A2 satisfy: 42° < (A1 + A2) / 2 < 49°, and 0.85 < A1 / A2 < 1.05.

[0118] In the examples provided in this application, the surface shape of the third lens 3 is more carefully regulated. The angles between the tangent lines at the maximum apertures of the object side (the side close to the display unit 12) and the image side (the side away from the display unit 12) of the third lens 3 and the optical axis are respectively set as A1 and A2, refer to Figure 2 . These two angles A1 and A2 are further designed to simultaneously meet two optical conditions: 42° < (A1 + A2) / 2 < 49°, and 0.85 < A1 / A2 < 1.05. This optical design not only reflects the optimized design of the surface shape of the third lens 3, but also aims to optimize the optical performance of the projection lens module.

[0119] Through this design in this example of the present application, the third lens 3 can better control the propagation path and refraction angle of light, effectively reducing the generation of aberrations such as field curvature, thereby significantly improving the clarity, contrast, and color restoration of the projection image. In addition, the regulation of the geometric characteristics of this lens also helps to enhance the optical stability during the zoom process, thus ensuring excellent imaging quality of the projection image at different focal lengths.

[0120] Generally speaking, this example of the present application brings more excellent optical performance and more stable and reliable imaging performance to the projection lens module through further optimization of the surface shape of the third lens 3.

[0121] In some examples of the present application, the sum T' of the central thicknesses of the first doublet lens, the second doublet lens, and the third doublet lens satisfies: 16% < T' / TTL < 33% with respect to the overall optical length TTL of the projection lens module.

[0122] In the example provided by the present application, a specific proportional relationship between the sum T' of the central thicknesses of the first doublet lens, the second doublet lens, and the third doublet lens and the overall optical length TTL of the projection lens module is described, that is, 16% < T' / TTL < 33%. This design reflects the control of the thicknesses of the three groups of doublet lenses used inside the projection lens module, aiming to further optimize the imaging performance, zoom stability, and overall structural compactness of the projection lens module.

[0123] By controlling the ratio of the sum T' of the central thicknesses of the above three groups of doublet lenses to the overall optical length TTL of the entire projection lens module, the light propagation path and refraction angle inside the projection lens module can be effectively adjusted, thereby optimizing various aberration corrections, significantly improving the clarity, contrast, and detail expressiveness of the projection image, so as to achieve the purpose of optimizing the imaging performance of the projection lens module. And, on the premise of ensuring optical performance, by controlling the ratio of the sum T' of the central thicknesses of the three built-in doublet lenses to the overall optical length TTL, it also helps to achieve the structural compactness design of the projection lens module.

[0124] In some examples of the present application, the central thickness T1' of the first doublet lens satisfies: 7% < T1' / TTL < 14% with respect to the overall optical length TTL of the projection lens module.

[0125] In the example provided by the present application, a specific proportional relationship between the central thickness T1' of the first doublet lens and the overall optical length TTL of the projection lens module is described, that is, 7% < T1' / TTL < 14%. It should be noted that the first doublet lens can move along the optical axis, and this design endows the projection lens module with the function of focusing.

[0126] In the present application, by reasonably controlling the ratio of the central thickness T1' of the first doublet lens to the overall optical length TTL of the projection lens module, the light propagation path and refraction angle inside the projection lens module can be optimized, thereby improving the aberration correction effect. This not only helps to enhance the clarity, contrast, and color reproduction of the projection image, but also provides a good foundation for the focusing function.

[0127] The first doublet lens moves along the optical axis, enabling the entire projection lens module to perform focusing. This focusing function ensures that the projection image can maintain the best focused state in different application scenarios, which helps to improve the imaging quality. Moreover, by further controlling the ratio range of T1' / TTL, it can ensure that the optical performance of the projection lens module remains stable during the zoom process, reducing the occurrence of image blurring and distortion. This not only improves the smoothness and accuracy of zooming, but also enhances the imaging consistency of the projection lens module at different focal lengths. In addition, on the premise of ensuring the optical performance and focusing function, by controlling the ratio of the central thickness T1' of the first doublet lens to the overall optical length TTL of the projection lens module, it helps to achieve a compact structural design of the projection lens module.

[0128] In some examples of the present application, refer to Figure 1 , the first doublet lens is composed of a first lens 1 and a second lens 2 glued together. Among them, the first lens 1 has a positive optical power, the second lens 2 has a negative optical power, and the refractive index N1 of the first lens 1 is lower than the refractive index N2 of the second lens 2.

[0129] In the examples provided in the present application, the first doublet lens is glued by a positive lens with a low refractive index and a negative lens with a high refractive index, and this design can effectively correct chromatic aberration. This is because after the positive lens with a low refractive index and the negative lens with a high refractive index are glued together, it can make light rays of different wavelengths have different deflection angles when passing through the glued lens, thereby achieving chromatic aberration correction on the imaging plane.

[0130] Specifically, the refractive index N1 of the first lens 1 (being a positive lens) is lower than the refractive index N2 of the second lens 2 (being a negative lens), and this combination is beneficial to eliminating chromatic aberration in the visible light range and improving the color reproduction and clarity of imaging. Based on this positive-negative gluing design, the first doublet lens can significantly improve the imaging quality while maintaining a high light transmittance.

[0131] Since the first doublet lens can effectively correct chromatic aberration and other aberrations, the projection lens module can maintain more stable imaging quality under different working environments and usage conditions. This is particularly important for commercial micro-projectors as they need to provide high-quality projection effects under various complex environmental conditions.

[0132] In one example, in the first doublet lens: the refractive index N1 of the first lens 1 (positive lens) ranges from 1.59 to 1.8, and the refractive index N2 of the second lens 2 (negative lens) ranges from 1.74 to 1.85. The refractive index ranges of the positive lens and the negative lens in the first lens group set in this example mainly consider the manufacturing cost and processing difficulty of the lens, while taking into account optical performance and manufacturing feasibility.

[0133] In some examples of the present application, the first lens group satisfies: 10 < (T3 + T1) / T2 < 14; where 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.

[0134] See Figure 1 , in the first lens group, the central thicknesses of the first lens 1 and the third lens 3 are relatively large, and they belong to two thick lenses in the first lens group. While the central thickness T2 of the second lens 2 is relatively smaller compared to the first lens 1 and the third lens 3, and it belongs to a thin lens in the first lens group. That is to say, two thick lenses are paired with one thin lens in the first lens group.

[0135] In this example of the present application, by adjusting the ratio between the total central thickness of the two thick lenses and the central thickness of one thin lens, it helps to optimize aberration correction, especially for key aberrations such as field curvature and spherical aberration. The combination of two thick lenses and one thin lens can more precisely control the refraction angle and propagation path of light, reduce the influence of aberrations on imaging quality, and improve the clarity and contrast of the image.

[0136] In particular, during the zooming process, the three lenses in the first lens group work together to maintain a stable propagation path of light. By controlling the range of (T3 + T1) / T2, it can ensure that the optical performance of the projection lens module remains stable during the zooming process, reduce image blurring and distortion phenomena, and improve the accuracy of zooming.

[0137] In some examples of the present application, see Figure 1, the second doublet lens is composed of a fourth lens 4 and a fifth lens 5 cemented together. Among them, the fourth lens 4 has a positive optical power, the fifth lens 5 has a negative optical power, and the refractive index N4 of the fourth lens 4 is lower than the refractive index N5 of the fifth lens 5. The third doublet lens is composed of a sixth lens 6 and a seventh lens 7 cemented together. Among them, the sixth lens 6 has a negative optical power, the seventh lens 7 has a positive optical power, and the refractive index N7 of the seventh lens 7 is lower than the refractive index N6 of the sixth lens 6.

[0138] In one example, in the second doublet lens: the refractive index N4 of the fourth lens 4 (positive lens) ranges from 1.59 to 1.8, and the refractive index N5 of the fifth lens 5 (negative lens) ranges from 1.74 to 1.85.

[0139] In one example, in the third doublet lens: the refractive index N4 of the seventh lens 7 (positive lens) ranges from 1.59 to 1.8, and the refractive index N6 of the sixth lens 6 (negative lens) ranges from 1.74 to 1.85.

[0140] In the projection lens module provided by the embodiments of the present application, refer to Figure 1 , a total of three doublet lenses are used, that is, a combined design of a first doublet lens, a second doublet lens, and a third doublet lens. This combined design of optical elements greatly improves the overall performance of the projection lens module. The following specifically analyzes the technical effects of this design in the present application.

[0141] One of the core advantages of the doublet lens lies in its excellent chromatic aberration correction ability. By cementing a negative lens with a high refractive index and a positive lens with a low refractive index together, the formed doublet lens can effectively compensate for the dispersion differences generated by light of different wavelengths when passing through the lens, thereby achieving the correction of chromatic aberration within the visible light range. In the projection lens module provided by the embodiments of the present application, the combined use of three groups of doublet lenses enhances this advantage. Each group of doublet lenses can correct chromatic aberration for light of a specific wavelength, and the combination of the three can cover a wider spectral range, providing a more comprehensive and accurate chromatic aberration correction effect. This not only ensures a high color reproduction degree of the projection image but also guarantees relatively high clarity of the edge image, greatly improving the overall visual experience.

[0142] In addition to chromatic aberration correction, the use of doublet lenses can also optimize other types of aberrations, such as spherical aberration, astigmatism, etc. In the design of the projection lens module of the present application, the combination of three groups of doublet lenses enables the light to be more comprehensively modulated when passing through the projection lens module, thereby achieving a significant improvement in the overall imaging quality.

[0143] In addition, due to the characteristics of the projection lens module of the present application, which has a large projection ratio (4 - 6) and variable focal length (21 - 32 mm), the use of three groups of doublet lenses provides optical support for achieving this design goal, ensuring high-quality projection images at different focal lengths and projection ratios.

[0144] In some examples of the present application, between the fourth lens 4, the fifth lens 5, the sixth lens 6, and the seventh lens 7, the following is satisfied: 3 < (T4 + T7) / (T5 + T6) < 4.8; where T4 is the central thickness of the fourth lens 4, T5 is the central thickness of the fifth lens 5, T6 is the central thickness of the sixth lens 6, and T7 is the central thickness of the seventh lens 7.

[0145] In the second lens group provided by the embodiment of the present application, the central thicknesses of the fourth lens 4 and the seventh lens 7 are relatively large, and they belong to the two thick lenses in the second lens group. While the central thicknesses of the fifth lens 5 and the sixth lens 6 are relatively small, and they belong to the two thin lenses in the second lens group.

[0146] In this example of the present application, by adjusting the ratio between the sum of the central thicknesses of the two thick lenses and the sum of the central thicknesses of the two thin lenses in the second lens group, it helps to optimize aberration correction. The reasonable combination and use of thick lenses and thin lenses can more precisely control the refraction angle and propagation path of light, reduce the influence of aberration on the imaging quality, and improve the clarity and contrast of the image.

[0147] In particular, by controlling the condition of 3 < (T4 + T7) / (T5 + T6) < 4.8, it can ensure that the optical performance of the projection lens module remains stable during the zooming process and improve the accuracy of zooming.

[0148] In some examples of the present application, the effective focal lengths of the lenses in the projection lens module satisfy:

[0149] The effective focal length of the first doublet lens is F', 70 mm ≤ F' ≤ 90 mm;

[0150] The effective focal length of the third lens 3 is F3, -20 mm ≤ F3 ≤ -13 mm;

[0151] The effective focal length of the second doublet lens is F'', 600 mm ≤ F'' ≤ 800 mm;

[0152] The effective focal length of the third doublet lens is F''', 25 mm ≤ F''' ≤ 37 mm;

[0153] The effective focal length of the eighth lens 8 is F8, 52 mm ≤ F8 ≤ 74 mm.

[0154] In the first lens group, the first doublet serves as the front group part of the entire projection lens module (it is located on the image side, away from the display unit 12). The range of its effective focal length ensures that the projection lens module can have a certain converging ability, so as to form a clear image within a relatively short focal length. This helps to achieve a high-quality projection effect within a limited space. Especially in commercial micro-projectors, the requirements for compactness and high performance are particularly important.

[0155] The range of the effective focal length F3 of the third lens 3 is designed to be -20mm ≤ F3 ≤ -13mm. The third lens 3 is part of the first lens group (the front group part of the projection lens module). This design range enables the projection lens module to better adapt to the requirements of different projection ratios and focal lengths, while reducing field curvature and improving imaging quality.

[0156] In the second lens group, the range of the effective focal length F'' of the second doublet is designed to be 600mm ≤ F'' ≤ 800mm. The second doublet is part of the rear group part of the projection lens module (it is located on the object side, close to the display unit 12). The design of its long focal length helps to further magnify and correct the light rays passing through the front group part. This range of long focal length, combined with the combination of high-refractive-index and low-refractive-index lenses, can effectively correct chromatic aberration and improve the color reproducibility and clarity of the projection image.

[0157] The range of the effective focal length F''' of the third doublet is designed to be 25mm ≤ F''' ≤ 37mm. The third doublet is also part of the rear group part of the projection lens module. The designed range of its focal length helps to adjust the light rays passing through the first lens group and the second doublet, further optimizing the imaging quality. In addition, the design of the third doublet also takes into account thermal stability and mechanical stability to ensure a stable projection effect under different working conditions.

[0158] The range of the effective focal length F8 of the eighth lens 8 is designed to be 52mm ≤ F8 ≤ 74mm. The focal length range of the eighth lens 8 can ensure that a clear projection image is formed on the imaging surface of the projection screen.

[0159] Through the specially designed range of the effective focal length of the lens, the projection lens module of the present application has achieved remarkable technical effects in aspects such as chromatic aberration correction, imaging quality improvement, and light path optimization. 。

[0160] In some examples of the present application, each lens in the projection lens module is a spherical lens.

[0161] Specifically, each lens in the projection lens module is designed as a glass spherical lens.

[0162] The glass spherical lens can meet the high imaging quality requirements of the projection lens module, and at the same time, the manufacturing cost is relatively low, which is conducive to reducing the production cost of the projection lens module. The glass spherical lens has good optical performance, which can reduce the scattering and absorption of light, and improve the clarity and contrast of imaging. In addition, the glass material has high thermal stability and chemical stability, and can maintain stable optical performance under different environmental conditions, which helps to enhance the stability of the entire projection lens module and improve the reliability and service life of the product.

[0163] In some examples of the present application, referring to Figure 1 , the projection lens module further includes a galvanometer 10 and a prism 11 that are sequentially arranged on the object side of the eighth lens 8.

[0164] In some examples of the present application, referring to Figure 1 , the projection lens module further includes a display unit 12 and a glass plate 13, and the glass plate 13 is located between the display unit 12 and the prism 11.

[0165] In some examples of the present application, 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 module satisfies: 1.7 < TTL / D1 < 2.7.

[0166] That is to say, in the projection lens module provided by the embodiments of the present application, not only two lens groups and a diaphragm 9 are included, but also a series of optical elements such as a galvanometer 10, a prism 11, a glass plate 13, and a display unit 12 are introduced, and specifically, the ratio range (1.7 < TTL / D1 < 2.7) between the total optical length TTL of the projection lens module and the maximum aperture D1 of the lens is specified.

[0167] Referring to Figure 1 , in the projection lens module, the aperture of the first lens 1 is the largest.

[0168] In the projection lens module of the embodiments of the present application, whether the galvanometer 10 is provided depends on specific application requirements.

[0169] Among them, the prism 11 can be used to further adjust the direction of light. By reasonably designing the shape and angle of the prism, precise control of the light path can be achieved to meet specific projection requirements. The prism 11 can be designed as a total internal reflection prism (TIR prism).

[0170] Among them, the display unit 12, as one of the components of the projection lens module, is responsible for generating and providing the light for projection imaging to the projection lens. The display unit 12 is, for example, a high-resolution display device such as an LCD, DLP, or LCOS, etc., which can generate high-quality image signals.

[0171] Among them, the glass plate 13 is placed between the display unit 12 and the prism 11, and is used to ensure that the light emitted from the display unit 12 can efficiently pass through the subsequent prism and lens group, and finally form a high-quality projection image. The glass plate 13 reduces the loss and interference of light during transmission through its characteristics such as high light transmittance and low reflectivity, which is beneficial to improving the brightness and contrast of the projection screen.

[0172] In some examples provided by the present application, the design that the range of TTL / D1 is between 1.7 and 2.7 is a key balance point between the compactness and optical performance of the projection lens module. A smaller ratio means that the projection lens module can be more compact, which is beneficial to reducing the overall volume and weight of the projection device. A larger ratio may provide a larger design space, which helps to optimize the optical performance. By controlling this ratio range, the present application not only ensures the compactness of the projection lens module but also guarantees its excellent optical performance.

[0173] In some examples of the present application, see Figure 1 , the overall optical length TTL of the projection lens module is 59mm < TTL < 85mm, and its maximum effective aperture is 33mm.

[0174] By controlling the overall optical length TTL between 59mm and 85mm, while ensuring the compactness of the projection lens module, enough space can be provided for optical design to achieve high-quality imaging effects. The maximum effective aperture of 33mm ensures that the projection lens module has sufficient light passing capacity and can provide a clear projection image under different lighting conditions.

[0175] In some examples of the present application, see Figure 1 and Table 1, the main parameters of the projection lens module include: the focal length is 21mm - 32mm, the projection ratio TR is 4 - 6, the relative aperture: 1 / 1.73, Offset: 0%, the pixel size: 5.4μm, the field of view angle is 5.2° - 8.1°, the image plane size is 5.5mm - 6.5mm, the working wavelength range is 455nm - 630nm, and the image plane size: 5.5mm - 6.5mm.

[0176] See Table 1, Table 1 shows Figure 1 some main optical parameters of the provided projection lens module.

[0177] Table 1

[0178]

[0179] The focal length of the projection lens module provided by the embodiment of the present application is 21 mm to 32 mm. Refer to Figure 22 , which covers a relatively wide focal length range, enabling the projection lens module to meet the requirements of different projection distances and screen sizes. The projection ratio of the projection lens module reaches 4 to 6, which means that a larger screen can be projected at the same projection distance, meeting the needs of large venues or long-distance projection.

[0180] The relative aperture of the projection lens module provided by the embodiment of the present application is 1 / 1.73, ensuring a sufficient aperture size so that the projection lens module can also provide a bright projection image in low-light environments.

[0181] The Offset of the projection lens module provided by the embodiment of the present application is 0%, which means that the projection image is perpendicular to the projector lens, and the problem of image offset can be avoided.

[0182] The pixel size of the projection lens module provided by the embodiment of the present application is 5.4 μm, ensuring the fineness and clarity of the projection image and enabling delicate image details to be presented.

[0183] The working wavelength range is 455 nm to 630 nm, which covers most of the visible light range, enabling the projection lens module provided by the embodiment of the present application to present rich colors and natural image effects.

[0184] The field of view angle is 5.2 to 8.1°. Although it is not particularly large, it provides a certain viewing angle range on the premise of ensuring the image quality. The design of this field of view angle meets the requirements of commercial micro-projection devices.

[0185] The image plane size is 5.5 mm to 6.5 mm, which matches the sensor size of mainstream projectors, ensuring the compatibility of the projection image and the best imaging effect.

[0186] Table 1 gives the optical parameter design in a certain state (such as the initial state). It should be noted that the projection lens module provided by the embodiment of the present application includes, but is not limited to, the optical design in Table 1. For others, reference can be made to Embodiments 1 to 3 in the following text.

[0187] For the projection lens module provided by the embodiment of the present application, its optical performance is as follows:

[0188] Refer to Figure 3 , Figure 3 is Figure 1and the distortion diagram of the projection lens module shown in Table 1, the absolute value of the distortion is less than 0.8%.

[0189] See Figure 4 , Figure 4 is Figure 1 and the MTF diagram of the projection lens module shown in Table 1, the MTF is > 0.5 at 93 lp / mm.

[0190] See Figure 5 , Figure 5 is Figure 1 and the dot array diagram of the projection lens module shown in Table 1, the maximum value of the image points in the dot diagram is less than 5 μm.

[0191] See Figure 6 , Figure 6 is Figure 1 the lateral chromatic aberration diagram of the projection lens module shown in

[0192] According to another embodiment of the present application, a micro-projection device is provided. The micro-projection device includes a housing and the projection lens module as described above.

[0193] The micro-projection device provided by the embodiments of the present application can be applied to commercial micro-projection devices.

[0194] The specific implementation manners of the micro-projection device of the embodiments of the present application can refer to the respective embodiments of the above projection lens module. Therefore, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be elaborated herein one by one.

[0195] The projection lens module of the present application will be described below through Embodiment 1 to Embodiment 3 respectively. Among them, Embodiment 1 is the long focal length mode of the projection lens module, Embodiment 2 is the medium focal length mode of the projection lens module, and Embodiment 3 is the short focal length mode of the projection lens module.

[0196] Embodiment 1

[0197] See Figure 7 , the projection lens module provided by Embodiment 1 includes a projection lens, a glass plate 13 and a display unit 12 arranged in sequence along the same optical axis; wherein, the display unit 12 is used to provide light for projection imaging to the projection lens, and the projection lens is used to project and image the light emitted by the display unit 12;

[0198] The projection lens includes a first lens group, a second lens group and a diaphragm 9 arranged along the same optical axis;

[0199] The first lens group includes a first doublet lens and a third lens 3 arranged along the optical axis, wherein the first doublet lens has positive focal power and is composed of a first lens 1 and a second lens 2 glued together, the first lens 1 has positive focal power, the second lens 2 has negative focal power, and the third lens 3 has negative focal power;

[0200] The second lens group includes a second doublet, a third doublet, and an eighth lens 8 sequentially arranged along the optical axis, wherein the second doublet, the third doublet, and the eighth lens 8 all have positive focal power, wherein the second doublet includes a fourth lens 4 and a fifth lens 5 cemented together, wherein the fourth lens 4 has positive focal power, and the fifth lens 5 has negative focal power; the third doublet includes a sixth lens 6 and a seventh lens 7 cemented together, wherein the sixth lens 6 is a negative lens, and the seventh lens 7 is a positive lens;

[0201] The first lens 1 to the eighth lens 8 in the projection lens are all glass spherical lenses;

[0202] The aperture 9 is located between the third lens 3 and the fourth lens 4;

[0203] The first doublet lens and the third doublet lens can move synchronously along the optical axis, and through the coordinated displacement of the two:

[0204] The movement of the first doublet lens is used to adjust the focal length of the projection lens module;

[0205] The movement of the third doublet lens is used to compensate for the image plane displacement caused by the change of focal length;

[0206] The projection lens module further includes a galvanometer mirror 10 and a prism 11 located on the object side of the eighth lens 8 and arranged in sequence along the optical axis.

[0207] The projection lens module provided in this embodiment 1 is in telephoto mode.

[0208] See also Figure 7 , Figure 7 The optical parameters of the projection lens module shown are shown in Table 2 below.

[0209] Table 2

[0210]

[0211] The projection lens module provided in this embodiment 1 has the following optical properties: Figures 8 to 11 As shown: Figure 8 is a point diagram diagram. Figure 9 is the MTF curve graph,Figure 10 It is the field curvature and distortion diagram, Figure 11 and it is the lateral chromatic aberration diagram.

[0212] See Figure 8 , for the projection lens module provided in Embodiment 1, the maximum value of the image points in the spot diagram is less than 3μm.

[0213] See Figure 9 , for the projection lens module provided in Embodiment 1, the MTF is > 0.35 at 125 lp / mm.

[0214] See Figure 10 , for the projection lens module provided in Embodiment 1, the maximum distortion occurs at the 1st field of view, and the absolute value is less than 0.15%.

[0215] See Figure 11 , for the projection lens module provided in Embodiment 1, the maximum chromatic aberration value is less than 1μm.

[0216] Embodiment 2

[0217] See Figure 12 , the projection lens module provided in Embodiment 2 includes a projection lens, a glass plate 13, and a display unit 12 arranged in sequence along the same optical axis; wherein, the display unit 12 is used to provide light for projection imaging to the projection lens, and the projection lens is used to perform projection imaging on the light emitted by the display unit 12;

[0218] The projection lens includes a first lens group, a second lens group, and a diaphragm 9 arranged along the same optical axis;

[0219] The first lens group includes a first doublet lens and a third lens 3 arranged along the optical axis. Among them, the first doublet lens has a positive optical power, the first doublet lens is composed of a first lens 1 and a second lens 2 glued together, the first lens 1 has a positive optical power, the second lens 2 has a negative optical power, and the third lens 3 has a negative optical power;

[0220] The second lens group includes a second doublet lens, a third doublet lens, and an eighth lens 8 arranged in sequence along the optical axis. The second doublet lens, the third doublet lens, and the eighth lens 8 all have positive optical powers. Among them, the second doublet lens includes a fourth lens 4 and a fifth lens 5 glued together, the fourth lens 4 has a positive optical power, and the fifth lens 5 has a negative optical power; the third doublet lens includes a sixth lens 6 and a seventh lens 7 glued together, where the sixth lens 6 is a negative lens and the seventh lens 7 is a positive lens;

[0221] The first lens 1 to the eighth lens 8 in the projection lens are all glass spherical lenses;

[0222] The diaphragm 9 is located between the third lens 3 and the fourth lens 4;

[0223] Wherein, the first doublet lens and the third doublet lens can move synchronously along the optical axis. Through their coordinated displacement:

[0224] The movement of the first doublet lens is used to adjust the focal length of the projection lens module;

[0225] The movement of the third doublet lens is used to compensate for the image plane displacement caused by the change in focal length;

[0226] The projection lens module further includes a galvanometer 10 and a prism 11 which are arranged in sequence along the optical axis on the object side of the eighth lens 8.

[0227] The projection lens module provided in Embodiment 2 is in the medium focal length mode.

[0228] See Figure 12 , Figure 12 For the optical parameters of the projection lens module shown, please refer to Table 3 below.

[0229] Table 3

[0230]

[0231] For the projection lens module provided in Embodiment 2, its optical performance is as Figures 13 to 16 shown: Figure 13 is the spot diagram schematic diagram, Figure 14 is the MTF curve graph, Figure 15 is the field curvature and distortion graph, Figure 16 is the lateral chromatic aberration graph.

[0232] See Figure 13 For the projection lens module provided in Embodiment 2, the maximum value of the image points in the spot diagram is less than 3μm.

[0233] See Figure 14 For the projection lens module provided in Embodiment 2, the MTF is > 0.35 at 125 lp / mm.

[0234] See Figure 15 For the projection lens module provided in Embodiment 2, the maximum distortion occurs at the 1st field of view, and the absolute value is less than 0.3%.

[0235] See Figure 16 For the projection lens module provided in Embodiment 2, the maximum chromatic aberration value is less than 2μm.

[0236] Embodiment 3

[0237] See Figure 17, the projection lens module provided in Embodiment 3 includes a projection lens, a glass plate 13, and a display unit 12 arranged in sequence along the same optical axis; wherein, the display unit 12 is used to provide light for projection imaging to the projection lens, and the projection lens is used to perform projection imaging on the light emitted by the display unit 12;

[0238] The projection lens includes a first lens group, a second lens group, and a diaphragm 9 arranged along the same optical axis;

[0239] The first lens group includes a first doublet lens and a third lens 3 arranged along the optical axis. Among them, the first doublet lens has a positive optical power, the first doublet lens is composed of a first lens 1 and a second lens 2 glued together, the first lens 1 has a positive optical power, the second lens 2 has a negative optical power, and the third lens 3 has a negative optical power;

[0240] The second lens group includes a second doublet lens, a third doublet lens, and an eighth lens 8 arranged in sequence along the optical axis. The second doublet lens, the third doublet lens, and the eighth lens 8 all have positive optical powers. Among them, the second doublet lens includes a fourth lens 4 and a fifth lens 5 glued together, the fourth lens 4 has a positive optical power, and the fifth lens 5 has a negative optical power; the third doublet lens includes a sixth lens 6 and a seventh lens 7 glued together, where the sixth lens 6 is a negative lens and the seventh lens 7 is a positive lens;

[0241] The first lens 1 to the eighth lens 8 in the projection lens are all glass spherical lenses;

[0242] The diaphragm 9 is located between the third lens 3 and the fourth lens 4;

[0243] Among them, the first doublet lens and the third doublet lens can move synchronously along the optical axis. Through their coordinated displacement:

[0244] The movement of the first doublet lens is used to adjust the focal length of the projection lens module;

[0245] The movement of the third doublet lens is used to compensate for the image plane displacement caused by the change in focal length;

[0246] The projection lens module further includes a galvanometer 10 and a prism 11 arranged in sequence along the optical axis on the object side of the eighth lens 8.

[0247] The projection lens module provided in this Embodiment 3 is in the short - focal mode.

[0248] See Figure 17 , Figure 17 For the optical parameters of the shown projection lens module, please refer to Table 4 below.

[0249] Table 4

[0250]

[0251] The projection lens module provided in Embodiment 3 has optical performance as Figures 18 to 21 shown below: Figure 18 is a spot diagram schematic diagram, Figure 19 is an MTF curve graph, Figure 20 is a field curvature and distortion graph, Figure 21 is a lateral chromatic aberration graph.

[0252] Referring to Figure 18 , for the projection lens module provided in Embodiment 3, the maximum value of the image points in the spot diagram is less than 4 μm.

[0253] Referring to Figure 19 , for the projection lens module provided in Embodiment 3, the MTF is > 0.4 at 125 lp / mm.

[0254] Referring to Figure 20 , for the projection lens module provided in Embodiment 3, the maximum distortion occurs at a 1° field of view and its absolute value is less than 0.7%.

[0255] Referring to Figure 21 , for the projection lens module provided in Embodiment 3, the maximum chromatic aberration value is less than 3 μm.

[0256] In the above embodiments, the differences between the various embodiments are mainly described. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a more optimal embodiment. For the sake of brevity of the text, it will not be elaborated here.

[0257] Although some specific embodiments of the present application have been described in detail by way of examples, those skilled in the art should understand that the above examples are only for the purpose of illustration and not for the purpose of limiting the scope of the present application. Those skilled in the art should understand that the above embodiments can be modified without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. A projection lens module, characterized in that, It sequentially includes a first lens group, a diaphragm (9), and a second lens group from the image side to the object side along the optical axis; The first lens group includes a first doublet lens and a third lens (3) arranged along the optical axis. The first doublet lens has a positive optical power, and the third lens (3) has a negative optical power; The second lens group includes a second doublet lens, a third doublet lens, and an eighth lens (8) arranged sequentially along the optical axis. The second doublet lens, the third doublet lens, and the eighth lens (8) all have positive optical powers; The diaphragm (9) is located between the third lens (3) and the second doublet lens; Among them, the first doublet lens and the third doublet lens can move synchronously along the optical axis. Through their coordinated displacement: The movement of the first doublet lens is used to adjust the focal length of the projection lens module; The movement of the third doublet lens is used to compensate for the image plane displacement caused by the change in focal length.

2. The projection lens module according to claim 1, wherein The central thickness T3 of the third lens (3) and the optical total length TTL of the projection lens module satisfy: 8% < T3 / TTL < 11.5%; 3. The projection lens module according to claim 1 or 2, characterized in that, The sagittal height at the maximum aperture of the image side of the third lens (3) is S1, and the sagittal height at the maximum aperture of its object side is S2. The ratio of S1 to S2 satisfies: 1.2 < S1 / S2 < 1.8; 4. The projection lens module according to claim 3, wherein, The angle between the tangent line at the maximum aperture of the object side of the third lens (3) and the optical axis is A1, and the angle between the tangent line at the maximum aperture of its image side and the optical axis is A2. A1 and A2 satisfy: 42° < (A1 + A2) / 2 < 49°, and 0.85 < A1 / A2 < 1.05; 5. The projection lens module according to claim 1, wherein The sum T' of the central thicknesses of the first doublet lens, the second doublet lens, and the third doublet lens and the optical total length TTL of the projection lens module satisfy: 16% < T' / TTL < 33%; 6. The projection lens module according to claim 1 or 5, characterized in that, The central thickness T1 of the first doublet lens and the optical total length TTL of the projection lens module satisfy: 7% < T1' / TTL < 14%; 7. The projection lens module according to claim 6, wherein The first doublet lens is composed of a first lens (1) and a second lens (2) glued together. Among them, the first lens (1) has a positive optical power, the second lens (2) has a negative optical power, and the refractive index N1 of the first lens (1) is lower than the refractive index N2 of the second lens (2); 8. The projection lens module according to claim 7, characterized in that, The first lens group satisfies: 10 < (T3 + T1) / T2 < 14; where 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); 9. The projection lens module according to claim 1 or 5, wherein The second doublet lens is composed of a fourth lens (4) and a fifth lens (5) glued together. Among them, the fourth lens (4) has a positive optical power, the fifth lens (5) has a negative optical power, and the refractive index N4 of the fourth lens (4) is lower than the refractive index N5 of the fifth lens (5); The third doublet lens is composed of a sixth lens (6) and a seventh lens (7) cemented together. Among them, the sixth lens (6) has a negative optical power, the seventh lens (7) has a positive optical power, and the refractive index N7 of the seventh lens (7) is lower than the refractive index N6 of the sixth lens (6).

10. The projection lens module according to claim 9, wherein, The following relationship is satisfied among the fourth lens (4), the fifth lens (5), the sixth lens (6) and the seventh lens (7): 3 < (T4 + T7) / (T5 + T6) < 4.8; where, T4 is the central thickness of the fourth lens (4), T5 is the central thickness of the fifth lens (5), T6 is the central thickness of the sixth lens (6), and T7 is the central thickness of the seventh lens (7).

11. The projection lens module according to claim 1, wherein, The effective focal lengths of the lenses in the projection lens module satisfy: The effective focal length of the first doublet lens is F', and 70 mm ≤ F' ≤ 90 mm; The effective focal length of the third lens (3) is F3, and -20 mm ≤ F3 ≤ -13 mm; The effective focal length of the second doublet lens is F'', and 600 mm ≤ F'' ≤ 800 mm; The effective focal length of the third doublet lens is F''', and 25 mm ≤ F''' ≤ 37 mm; The effective focal length of the eighth lens (8) is F8, and 52 mm ≤ F8 ≤ 74 mm; All the lenses in the projection lens module are glass spherical lenses.

12. The projection lens module according to claim 1, wherein The projection lens module further includes a galvanometer (10), a prism (11), a glass plate (13) and a display unit (12) which are sequentially arranged on the object side of the eighth lens (8); The ratio of the overall optical length TTL of the projection lens module to the maximum aperture D1 of the lens in the projection lens module satisfies: 1.7 < TTL / D1 < 2.

7.

13. The projection lens module according to claim 12, wherein The overall optical length TTL of the projection lens module is 59 mm < TTL < 85 mm, and the maximum effective aperture is 33 mm.

14. The projection lens module according to claim 13, wherein The optical parameters of the projection lens module include: the focal length is 21 mm to 32 mm, the projection ratio TR is 4 to 6, the relative aperture is 1 / 1.73, the offset of the image plane center relative to the optical axis Offset: is 0%, the pixel size is 5.4 μm, the field of view angle is 5.2° to 8.1°, the image plane size is 5.5 mm to 6.5 mm, and the working wavelength band is 455 nm to 630 nm.

15. A micro projection device, characterized in that, Including: A housing; And The projection lens module according to any one of claims 1 - 14.

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