Small projection lens

Abstract

The utility model relates to a small projection lens. Comprising a first lens with positive focal power, a second lens with negative focal power, a third lens with negative focal power, a fourth lens with positive focal power, a fifth lens with positive focal power, a diaphragm, a sixth lens with positive focal power and a seventh lens with negative focal power which are sequentially arranged along the direction of an optical axis, the small projection lens comprises a first lens with positive focal power, an eighth lens with positive focal power, a ninth lens with negative focal power, a tenth lens with positive focal power and an eleventh lens with positive focal power, and the effective focal length and the total length of the small projection lens are reasonably set. The camera lens is small in size, low in cost, small in projection ratio and large in aperture, can be matched with multiple DMD chips, provides enough projection brightness and size, is clear and sharp in projection picture, high in contrast ratio and accurate in color restoration, and meets strict use requirements under vehicle-mounted high and low temperature environment conditions at the same time.

Description

Technical Field

[0001] The utility model belongs to the technical field of optical lenses, and in particular relates to a small projection lens. Background Art

[0002] With the rapid development of new energy vehicles, the comfort of in-vehicle space has been greatly improved, and in-vehicle entertainment projects have gradually increased. Traditional entertainment projects mainly include in-vehicle TVs, but they are limited by the space and safety of the car. The size of in-vehicle TVs is relatively small and cannot meet the needs of more diversified and immersive entertainment interactions. Projection equipment can project a huge picture in a small space and is a better solution. However, traditional projectors are too large and cannot meet the stringent usage requirements of the car, such as high and low temperatures, which hinders the application of projection equipment in the in-vehicle space. Utility Model Content

[0003] The purpose of this utility model is to address the above-mentioned problems and propose a small projection lens with a small size, suitable projection distance, small throw ratio, large aperture, which can match a variety of DMD chips and provide sufficient projection brightness and size. The projected image is clear and sharp, with high contrast and accurate color reproduction, while meeting the stringent usage requirements of the vehicle in -40℃ ~ +85℃ environmental conditions.

[0004] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0005] The utility model provides a small projection lens, comprising a first lens with positive focal power, a second lens with negative focal power, a third lens with negative focal power, a fourth lens with positive focal power, a fifth lens with positive focal power, an aperture, a sixth lens with positive focal power, a seventh lens with negative focal power, an eighth lens with positive focal power, a ninth lens with negative focal power, a tenth lens with positive focal power, and an eleventh lens with positive focal power, which are sequentially arranged along an optical axis.

[0006] The small projection lens also meets the following conditions:

[0007] 9.5≤f≤10.5;58≤OAL≤72;

[0008] Wherein, f is the effective focal length of the small projection lens, in mm; OAL is the on-axis distance from the object side of the first lens to the image side of the eleventh lens, in mm.

[0009] Preferably, the small projection lens also meets the following conditions:

[0010]

[0011] Where D is the entrance pupil diameter, in mm.

[0012] Preferably, the small projection lens also meets the following conditions:

[0013]

[0014] Wherein, SD1 is the marginal ray height of the object-side surface of the first lens, and SD11 is the marginal ray height of the image-side surface of the eleventh lens.

[0015] Preferably, the small projection lens also meets the following conditions:

[0016] 6≤th4+th5+th11≤10

[0017] Wherein, th4 is the middle thickness of the fourth lens, th5 is the middle thickness of the fifth lens, and th11 is the middle thickness of the eleventh lens, and the unit is mm.

[0018] Preferably, the small projection lens also meets the following conditions:

[0019] 110≤abv6+abv8≤160

[0020] Wherein, abv6 is the Abbe number of the sixth lens, and abv8 is the Abbe number of the eighth lens.

[0021] Preferably, the small projection lens also meets the following conditions:

[0022]

[0023] Wherein, f1 is the effective focal length of the first lens, f2 is the effective focal length of the second lens, and f3 is the effective focal length of the third lens, all in mm.

[0024] Preferably, the small projection lens also meets the following conditions:

[0025]

[0026] -0.85% ≤ DIST ≤ -0.1%;

[0027] RI ≥ 60%;

[0028] Among them, FOV is the full field of view angle of the maximum field of view, DIST is the maximum optical distortion from the center to the edge of the field of view, and RI is the relative illumination of the small projection lens on the image plane.

[0029] Preferably, the small projection lens further comprises a galvanometer mirror and a prism sequentially arranged along the optical axis, and the galvanometer mirror and the prism are located between the eleventh lens and the image plane.

[0030] Preferably, the small projection lens also meets the following conditions:

[0031]

[0032] Wherein, f4 is the effective focal length of the fourth lens, in mm, R41 is the radius of curvature of the object side surface of the fourth lens, and R42 is the radius of curvature of the image side surface of the fourth lens, in mm.

[0033] Preferably, the small projection lens also meets the following conditions:

[0034] CRA≤2.4°,20≤FFL≤30

[0035] Wherein, CRA is the maximum incident angle of the small projection lens on the image plane, and FFL is the on-axis distance from the image side surface of the eleventh lens to the image plane, in mm.

[0036] Compared with the prior art, the beneficial effects of the present invention are:

[0037] This small projection lens utilizes an eleven-lens architecture, resulting in a compact size that reduces costs while ensuring image quality. The lens's compact structure is achieved through the rational distribution of optical power, keeping the total lens length under 72mm and the throw ratio TR range from 1.28 to 1.36. Various aberrations are corrected, improving edge quality and, consequently, image quality. The lens boasts a maximum aperture of F1.64, enabling it to deliver greater light output. The rational design of complementary materials ensures the lens maintains focus in ambient temperatures of -40°C to +85°C. The all-glass lens architecture further extends the operating range to high-temperature environments up to 105°C, resulting in more stable performance. The lens is compatible with a 0.33" DMD chip with an offset of 110%, resulting in high pixel count and improved image quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a schematic structural diagram of a small projection lens according to Example 1 of the present utility model;

[0039] Figure 2 This is a diagram showing the longitudinal spherical aberration, astigmatism, and distortion of the small projection lens in Example 1 of the present utility model;

[0040] Figure 3 This is a schematic structural diagram of a small projection lens according to Example 2 of the present utility model;

[0041] Figure 4 This is a diagram showing the longitudinal spherical aberration, astigmatism, and distortion of the small projection lens in Example 2 of the present utility model;

[0042] Figure 5 This is a schematic structural diagram of a small projection lens according to Example 3 of the present utility model;

[0043] Figure 6 This is a diagram showing the longitudinal spherical aberration, astigmatism, and distortion of the small projection lens in Example 3 of the present utility model;

[0044] Figure 7 This is a schematic structural diagram of a small projection lens according to Example 4 of the present utility model;

[0045] Figure 8 These are the longitudinal spherical aberration diagram, astigmatism diagram, and distortion diagram of the small projection lens according to Example 4 of the present utility model.

[0046] Explanation of the reference numerals: L1, first lens; L2, second lens; L3, third lens; L4, fourth lens; L5, fifth lens; L6, sixth lens; L7, seventh lens; L8, eighth lens; L9, ninth lens; L10, tenth lens; L11, eleventh lens; L12, galvanometer; L13, prism; STO, aperture; CG, protective glass. DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0048] It should be noted that, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0049] A small projection lens comprises a first lens L1 with positive focal power, a second lens L2 with negative focal power, a third lens L3 with negative focal power, a fourth lens L4 with positive focal power, a fifth lens L5 with positive focal power, an aperture STO, a sixth lens L6 with positive focal power, a seventh lens L7 with negative focal power, an eighth lens L8 with positive focal power, a ninth lens L9 with negative focal power, a tenth lens L10 with positive focal power, and an eleventh lens L11 with positive focal power, which are arranged in sequence along an optical axis.

[0050] The small projection lens also meets the following conditions:

[0051] 9.5≤f≤10.5;58≤OAL≤72;

[0052] Wherein, f is the effective focal length of the small projection lens, in mm; OAL is the on-axis distance from the object-side surface of the first lens L1 to the image-side surface of the eleventh lens L11, in mm.

[0053] The small projection lens includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10, and an eleventh lens L11, which are arranged in sequence along the optical axis. The first lens L1 has positive focal length, providing sufficient light height for the edge field of view, which is beneficial for reducing optical distortion at the edge and providing a solution for small front-end aperture; the second lens L2 has negative focal length, which can quickly compress the light height and cooperate with the first lens L1 to reduce the head size; the third lens L3 has negative focal length, which shares the focal length of the second lens L2, provides a deflection angle for the edge light, smoothes the light, and reduces the field of view aberration; the fourth lens L4 has positive focal length, its object side surface is concave, and its image side surface is convex, and is in a meniscus shape. And the height of the convex light is higher, which provides a certain field curvature compensation for the system, making the MTF concentration of the optical system very high; the fifth lens L5 with positive focal length connects the front and rear lens groups (such as divided by the aperture STO, the lens on the object side of the aperture STO is the front lens group, and the lens on the image side is the rear lens group). By arranging the aperture STO on its image side, the light trend near the aperture STO is smooth, which helps to reduce the sensitivity of the lens and improve the product yield and reliability; by setting the aperture STO between the fifth lens L5 and the sixth lens L6, that is, the aperture STO is located in the middle of the lens, which helps to balance the upper and lower light in the edge field of view, ensure the brightness of the edge while reducing the main ray angle of the lens, so that the lens can better match the projection optical system; the sixth lens L6 with positive focal length has a large Abbe number, which can reduce the introduction of chromatic aberration for the system; the seventh lens L7 with negative focal length has a small Abbe number, and the combination of positive and negative focal lengths with the sixth lens L6 can reduce the chromatic aberration of the entire system; the eighth lens L8 with positive focal length is also made of high Abbe number material, which reduces the introduction of chromatic aberration and is compatible with the negative lens L6. The lenses (such as the seventh lens L7 and the ninth lens L9) form a complementary chromatic aberration and spherical aberration relationship; the ninth lens L9 with negative optical power and the tenth lens L10 with positive optical power form a doublet, or also form a triplet with the eighth lens L8, which can greatly reduce the overall chromatic aberration of the system, ensure low levels of axial chromatic aberration and vertical chromatic aberration, and achieve simultaneous clarity of monochromatic and mixed light; the eleventh lens L11 with positive optical power has a high refractive index and a flat surface, which helps to reduce spherical aberration and correct the incident angle of the principal ray.

[0054] The f-values ​​of this small projection lens can be: 9.87, 9.86, 10.258, 10.268, 10.45, and 9.3 (units: mm). Meeting the above conditions, paired with a 0.33mm DMD chip with an offset of 110% (offset refers to the offset of the DMD chip relative to the optical axis), allows the lens to have wide-angle characteristics and a wide viewing angle, allowing it to project the desired image even at short distances. Exceeding the upper limit of the range narrows the lens angle and reduces the image size. Below the lower limit, the lens angle increases, requiring a more complex design and failing to meet the requirements for miniaturization and low cost. Furthermore, the OAL values ​​can be: 62.4, 61.4, 68.5, 67.8, 70.3, and 60.6 (units: mm). Meeting the above conditions allows the lens to be compact and meet miniaturization requirements. Exceeding the upper limit fails to meet miniaturization requirements. Below the lower limit, the lens space is compressed, which is not conducive to improved clarity, and the materials are more expensive, which can lead to excessive costs. After being assembled with the lens barrel, the small projection lens can better adapt to the vehicle vibration environment and has good stability.

[0055] In one embodiment, the small projection lens further meets the following conditions:

[0056]

[0057] Where D is the entrance pupil diameter, in mm.

[0058] Specifically, the f / D values ​​can be: 1.7, 1.8, 2.0, 2.05, 1.65, and 1.9. Meeting the above conditions allows the lens to have a large aperture, which can meet the needs of both low-cost and low-light projection equipment and high-light projection equipment. This gives the lens a wide range of uses and meets the needs of most projection scenarios on the market.

[0059] In one embodiment, the small projection lens further meets the following conditions:

[0060]

[0061] Wherein, SD1 is the marginal ray height on the object-side surface of the first lens L1, and SD11 is the marginal ray height on the image-side surface of the eleventh lens L11.

[0062] Specifically, the SD1 / SD11 value can be: 1.39, 1.43, 1.31, 1.264, 1.202, 1.41. Satisfying the above condition formula, the aperture of the first lens L1 of the lens and the aperture of the eleventh lens L11 are very small, the structure head and tail diameters are basically consistent, which is beneficial to the miniaturization design of the whole projection, also helps to reduce the exposed area of the projection, improves the integration, reduces the discomfort of exposure, and improves the beauty of the projection equipment in the vehicle space. Exceeding the upper limit value, the head size is too large, reducing the beauty of the application; below the lower limit value, the head size is too small, the design difficulty is large, and more lenses are needed to compensate for the optical distortion caused by the small head, which is not conducive to cost reduction.

[0063] In an embodiment, the small projection lens also satisfies the following conditions:

[0064] 6≤th4+th5+th11≤10

[0065] Wherein, th4 is the middle thickness of the fourth lens L4, th5 is the middle thickness of the fifth lens L5, and th11 is the middle thickness of the eleventh lens L11, unit mm.

[0066] Specifically, the th4+th5+th11 value can be: 9.59, 8.38, 7.5, 7.9, 7.2, 6.8, unit: mm. Due to the distribution of optical power, the fourth lens L4, the fifth lens L5 and the eleventh lens L11 are often high refractive index materials, and the short wave transmittance of high refractive index materials is not high due to their own characteristics. In order to enhance the short wave transmittance of the lens, the thickness of the high refractive index material needs to be strictly controlled, the total thickness of the high refractive index material can be controlled in a reasonable range to ensure that the short wave transmittance and long wave transmittance of the lens are small, and the color temperature deviation problem is avoided; exceeding the upper limit value, the thickness of the fourth lens L4, the fifth lens L5 and the eleventh lens L11 is too thick, which easily causes the short wave transmittance to be low, affecting the color temperature and brightness of the projection picture; below the lower limit value, the thickness of the lens is too thin, which is not conducive to processing.

[0067] In an embodiment, the small projection lens also satisfies the following conditions:

[0068] 110≤abv6+abv8≤160

[0069] Wherein, abv6 is the Abbe number of the sixth lens L6, and abv8 is the Abbe number of the eighth lens L8.

[0070] Specifically, the values ​​of abv6+abv8 can be: 122.35, 133.78, 149.94, 120.48, 150.62, 155.32, and 145.26. The sixth and eighth lenses, L6 and L8, are made of low-refractive-index, high-Abbe-number materials, and their material range is close to that of negative dndt materials. (dndt is the temperature coefficient of refractive index.) Satisfying the above conditional equation, suitable negative dndt materials can be selected for the sixth and eighth lenses, L6 and L8, to compensate for the expansion and contraction of excessive back focus at high and low temperatures. This achieves an athermal optical design, meeting the vehicle's -40°C to 85°C temperature range. When no plastic lens is used, the high-temperature range can be extended to 105°C. Outside the specified range, the material selection cannot meet the high and low-temperature compensation requirements.

[0071] In one embodiment, the small projection lens further meets the following conditions:

[0072]

[0073] Wherein, f1 is the effective focal length of the first lens L1, f2 is the effective focal length of the second lens L2, and f3 is the effective focal length of the third lens L3, all in mm.

[0074] Specifically, the values ​​of f1 / (f2+f3) can be: -1.05, -1.09, -1.36, -1.33, -1.25, -1.13. Meeting this conditional expression means that the first lens L1, the second lens L2, and the third lens L3 have a positive and negative power combination, and the effective focal length is limited to a reasonable range. This combination of positive and negative lenses can achieve a small aperture and low distortion, reducing the introduction of aberrations and improving overall clarity. Exceeding this range results in uneven power matching, making it difficult to achieve a small head solution.

[0075] In one embodiment, the small projection lens further meets the following conditions:

[0076]

[0077] -0.85% ≤ DIST ≤ -0.1%;

[0078] RI ≥ 60%;

[0079] Among them, FOV is the full field of view angle of the maximum field of view, DIST is the maximum optical distortion from the center to the edge of the field of view, and RI is the relative illumination of the small projection lens on the image plane.

[0080] Specifically, the FOV / DIST values ​​can be: -79.12, -80.2, -96.93, -76.64, -105.3, and -92.3, with units of ° / %. Meeting the above conditional expression allows for a wide-angle FOV, keeping the maximum optical distortion within a reasonable range. This is particularly suitable for full-glass distortion compensation, keeping the lens within reasonable FOV and DIST ranges, ensuring minimal distortion in both the projected size and image format. Alternatively, DIST can be: -0.75%, -0.76%, -0.6%, -0.65%, -0.55%, and -0.5%. Meeting the above conditional expression indicates that the lens's optical distortion is within a reasonable range, with projected TV distortion less than 0.5%. This distortion is barely noticeable to the human eye, contributing to improved viewing comfort. Exceeding this range results in excessive optical distortion, causing significant distortion in the projected image, which can cause viewing discomfort. RI values ​​can be: 65%, 68%, 70%, 72%, 75%, and 78%. Meeting the above conditions ensures good illumination uniformity within the Offset 100% range, preventing vignetting caused by low illumination at the edges. Exceeding this range results in low illumination, which can easily cause vignetting and impact viewing comfort.

[0081] In one embodiment, the small projection lens further includes a galvanometer mirror L12 and a prism L13 sequentially arranged along the optical axis. The galvanometer mirror L12 and the prism L13 are located between the eleventh lens L11 and the image plane.

[0082] The galvanometer G5 is used to vibrate at high frequencies in different directions, briefly expanding the image pixel range beyond the original pixel. This utilizes the persistence of vision effect to increase the number of pixels recognized by the human eye, thereby improving projection resolution. The prism G6 is equivalent to a flat plate and is used to aggregate light from different light sources, such as providing appropriate reflection and refraction angles for each light source. This technology is well known to those skilled in the art and will not be elaborated on here.

[0083] In one embodiment, the small projection lens further meets the following conditions:

[0084]

[0085] Wherein, f4 is the effective focal length of the fourth lens element L4, and the unit is mm; R41 is the radius of curvature of the object side surface of the fourth lens element L4; and R42 is the radius of curvature of the image side surface of the fourth lens element L4, and the unit is mm.

[0086] Specifically, the f4 / f values ​​can be: 2.4, 4.3, 5.5, 6.4, 7.6, and 8.3. If the above conditional formula is met, the fourth lens element L4 has positive focal power and is relatively small in the lens, which can quickly raise the light height and reduce the tolerance sensitivity of the fourth lens element L4 and the fifth lens element L5. Furthermore, R41 / R42 can be: 1.2, 3.4, 6.3, 8.2, 10.8, and 13.7. The object-side and image-side surfaces of the fourth lens element L4 have the same curvature direction. This can increase the light height difference between the concave and convex surfaces, provide sufficient field curvature compensation, reduce system field curvature and astigmatism, and unify the resolution level at the center and four corners of the projected image. Exceeding this range will increase the focal power of the fourth lens element L4 or change the sign of the focal power, resulting in concentrated lens sensitivity and unfavorable for mass production.

[0087] In one embodiment, the small projection lens further meets the following conditions:

[0088] CRA≤2.4°,20≤FFL≤30

[0089] Wherein, CRA is the maximum incident angle of the small projection lens on the image plane, and FFL is the on-axis distance from the image side surface of the eleventh lens L11 to the image plane, in mm.

[0090] Specifically, the CRA values ​​can be: 1.95, 2.2, 1.0, 1.5, 0.8, 0.5, in degrees. If the above conditional formula is met, the telecentricity of the lens is controlled within a very small range, ensuring that the lens is aligned with the light output direction, improving the light output efficiency from the center to the edge of the picture, and avoiding uneven brightness; if it exceeds this range, the telecentricity is too large, which can easily cause low light output efficiency and affect the brightness and uniformity of the picture. In addition, the FFL values ​​can be: 20.5, 22, 25.6, 27.7, 28.3, 29.6, in mm. If the above conditional formula is met, the lens can match a larger back focus, sufficient prism space and light output heat dissipation space, and match more projector optical machines; if it exceeds the upper limit, the back focus is too large, increasing the difficulty and cost of lens design; if it is below the lower limit, the back focus is too small, which is not conducive to the arrangement of the lighting light path and the heat dissipation of the projector optical machine, affecting the user experience.

[0091] For ease of understanding, the following is a detailed description using specific embodiments. The reference wavelength for the effective focal length, Abbe number, and refractive index in each embodiment is 520 nm.

[0092] Example 1:

[0093] like Figure 1As shown, in this embodiment, the compact projection lens includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, an aperture STO, a sixth lens L6, a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10, an eleventh lens L11, a galvanometer L12, a prism L13, and a cover glass CG, arranged in sequence along the optical axis. The ninth lens L9 and the tenth lens L10 form a cemented doublet. This optical system has an effective focal length of f = 10.268 mm, an aperture number Fno = 2.0, a field of view of 58.25°, and an on-axis distance OAL from the object side surface of the first lens L1 to the image side surface of the eleventh lens L11 = 67.8 mm. This optical system can achieve wide-angle characteristics, a large aperture, miniaturization, and a small head design.

[0094] Specifically, the parameter values ​​of the small projection lens in this embodiment are shown in Table 1 below:

[0095] Table 1

[0096]

[0097]

[0098] like Figure 1 As shown, the surface number S0 represents the object surface, the surface numbers S1, S3, S5, S7, S9, S11, S13, S15, S17, S18, S20, S22, S24 to S26 represent the object side surfaces of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, the ninth lens L9, the tenth lens L10, the eleventh lens L11, the galvanometer L12, the prism L13 and the cover glass CG, and the surface numbers S2, S4, S6 , S8, S10, S12, S14, S16, S18, S19, S21, S23, S25 to S27 respectively represent the image side surfaces of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, the ninth lens L9, the tenth lens L10, the eleventh lens L11, the galvanometer L12, the prism L13 and the cover glass CG. The cemented surfaces of the cemented lens group are regarded as one surface. STO represents the aperture stop. The surface number S28 represents the image plane IMA.

[0099] Figure 2The optical system includes a longitudinal spherical aberration diagram (LONGITUD INAL SPHERICAL ABER.), which shows the deviation of the convergent focus of light of different wavelengths passing through the lens. The ordinate of the longitudinal spherical aberration diagram represents the normalized pupil coordinate (Normalized Pupil Coordinator) from the center of the pupil to the edge of the pupil, and the abscissa represents the distance from the image plane to the intersection of the light and the optical axis (unit: mm). As can be seen from the longitudinal spherical aberration diagram, the degree of deviation of the convergent focus of light of each wavelength in this embodiment tends to be consistent and is within 0.025mm. The diffuse speckle or color halo in the imaging image is effectively suppressed, and the difference between single wavelength and complex wavelength is small. Figure 2 Also included are astigmatic field curvature diagrams for the optical system, where the S curve represents sagittal field curvature at a wavelength of 520nm, and the T curve represents meridional field curvature at a wavelength of 520nm. As can be seen from the diagram, the optical system's field curvature is within 0.025mm, and both field curvature and astigmatism are well corrected across all fields of view, resulting in sharp images at the center and edges of the field of view. Figure 2 The optical system's distortion diagram (DISTORTION) is also included. As can be seen from the diagram, optical distortion is within -1%, and image deformation caused by the main beam is minimal, demonstrating excellent imaging quality. In summary, the optical system's longitudinal spherical aberration, field curvature, and distortion are all well controlled, resulting in excellent imaging quality.

[0100] Example 2:

[0101] like Figure 3 As shown, in this embodiment, the compact projection lens includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, an aperture STO, a sixth lens L6, a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10, an eleventh lens L11, a galvanometer L12, a prism L13, and a cover glass CG, arranged in sequence along the optical axis. The eighth lens L8, the ninth lens L9, and the tenth lens L10 form a cemented triplet. This optical system has an effective focal length of f = 9.87 mm, an aperture number Fno = 1.7, a field of view of 60.13°, and an on-axis distance OAL from the object side surface of the first lens L1 to the image side surface of the eleventh lens L11 = 62.4 mm. This optical system can achieve wide-angle characteristics, a large aperture, miniaturization, and a small head design.

[0102] Specifically, the parameter values ​​of the small projection lens in this embodiment are shown in Table 2 below:

[0103] Table 2

[0104]

[0105]

[0106] like Figure 3 As shown, the surface number S0 represents the object surface, the surface numbers S1, S3, S5, S7, S9, S11, S13, S15, S16, S17, S19, S21, S23 to S25 represent the object side surfaces of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, the ninth lens L9, the tenth lens L10, the eleventh lens L11, the galvanometer L12, the prism L13 and the cover glass CG, and the surface numbers S2, S4, S6 , S8, S10, S12, S14, S16, S17, S18, S20, S22, S24 to S26 respectively represent the image side surfaces of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, the ninth lens L9, the tenth lens L10, the eleventh lens L11, the galvanometer L12, the prism L13 and the cover glass CG. The cemented surfaces of the cemented lens group are regarded as one surface. STO represents the aperture stop. The surface number S27 represents the image plane IMA.

[0107] Figure 4 The optical system includes a longitudinal spherical aberration diagram (LONGITUD INAL SPHERICAL ABER.), which shows the deviation of the convergent focus of light of different wavelengths passing through the lens. The ordinate of the longitudinal spherical aberration diagram represents the normalized pupil coordinate (Normalized Pupil Coordinator) from the center of the pupil to the edge of the pupil, and the abscissa represents the distance from the image plane to the intersection of the light and the optical axis (unit: mm). As can be seen from the longitudinal spherical aberration diagram, the degree of deviation of the convergent focus of light of each wavelength in this embodiment tends to be consistent and is within 0.025mm. The diffuse speckle or color halo in the imaging image is effectively suppressed, and the difference between single wavelength and complex wavelength is small. Figure 4 Also included are astigmatic field curvature diagrams for the optical system, where the S curve represents sagittal field curvature at a wavelength of 520nm, and the T curve represents meridional field curvature at a wavelength of 520nm. As can be seen from the diagram, the optical system's field curvature is within 0.025mm, and both field curvature and astigmatism are well corrected across all fields of view, resulting in sharp images at the center and edges of the field of view. Figure 4 The optical system's distortion diagram (DISTORTION) is also included. As can be seen from the diagram, optical distortion is within -1%, and image deformation caused by the main beam is minimal, demonstrating excellent imaging quality. In summary, the optical system's longitudinal spherical aberration, field curvature, and distortion are all well controlled, resulting in excellent imaging quality.

[0108] Example 3:

[0109] As Figure 5 shown, in this embodiment, the small projection lens includes first lens L1, second lens L2, third lens L3, fourth lens L4, fifth lens L5, diaphragm STO, sixth lens L6, seventh lens L7, eighth lens L8, ninth lens L9, tenth lens L10, eleventh lens L11, galvanometer L12, prism L13 and protective glass CG arranged in sequence along the optical axis direction, wherein the ninth lens L9 and the tenth lens L10 constitute a doublet lens. The effective focal length of this optical system is f=9.86mm, the aperture number Fno=1.8, the field of view angle is 60.14°, the on-axis distance OAL from the object side of the first lens L1 to the image side of the eleventh lens L11 is 61.4mm; it can be known that this optical system can realize wide-angle characteristics, large aperture, miniaturization and small head design.

[0110] Specifically, in this embodiment, the parameter values of the small projection lens are as follows in Table 3:

[0111] Table 3

[0112]

[0113]

[0114] As Figure 5 shown, wherein the surface number S0 represents the object plane, the surface numbers S1, S3, S5, S7, S9, S11, S13, S15, S17, S18, S20, S22, S24 to S26 represent the object side of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, the ninth lens L9, the tenth lens L10, the eleventh lens L11, the galvanometer L12, the prism L13 and the protective glass CG in sequence, the surface numbers S2, S4, S6, S8, S10, S12, S14, S16, S18, S19, S21, S23, S25 to S27 represent the image side of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, the ninth lens L9, the tenth lens L10, the eleventh lens L11, the galvanometer L12, the prism L13 and the protective glass CG in sequence, the cemented surface of the cemented lens group is regarded as one surface, STO represents the diaphragm, and the surface number S28 represents the image plane IMA.

[0115] Figure 6The optical system includes a longitudinal spherical aberration diagram (LONGITUD INAL SPHERICAL ABER.), which shows the deviation of the convergent focus of light of different wavelengths passing through the lens. The ordinate of the longitudinal spherical aberration diagram represents the normalized pupil coordinate (Normalized Pupil Coordinator) from the center of the pupil to the edge of the pupil, and the abscissa represents the distance from the image plane to the intersection of the light and the optical axis (unit: mm). As can be seen from the longitudinal spherical aberration diagram, the degree of deviation of the convergent focus of light of each wavelength in this embodiment tends to be consistent and is within 0.025mm. The diffuse speckle or color halo in the imaging image is effectively suppressed, and the difference between single wavelength and complex wavelength is small. Figure 6 Also included are astigmatic field curvature diagrams for the optical system, where the S curve represents sagittal field curvature at a wavelength of 520nm, and the T curve represents meridional field curvature at a wavelength of 520nm. As can be seen from the diagram, the optical system's field curvature is within 0.025mm, and both field curvature and astigmatism are well corrected across all fields of view, resulting in sharp images at the center and edges of the field of view. Figure 6 The optical system's distortion diagram (DISTORTION) is also included. As can be seen from the diagram, optical distortion is within -1%, and image deformation caused by the main beam is minimal, demonstrating excellent imaging quality. In summary, the optical system's longitudinal spherical aberration, field curvature, and distortion are all well controlled, resulting in excellent imaging quality.

[0116] Example 4:

[0117] like Figure 7 As shown, in this embodiment, the small projection lens includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, an aperture STO, a sixth lens L6, a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10, an eleventh lens L11, a galvanometer L12, a prism L13, and a cover glass CG, arranged in sequence along the optical axis. The ninth lens L9 and the tenth lens L10 form a cemented doublet. This optical system has an effective focal length of f = 10.258 mm, an aperture number Fno = 2.0, a field of view of 58.16°, and an on-axis distance OAL from the object side of the first lens L1 to the image side of the eleventh lens L11 = 68.5 mm. This optical system can achieve wide-angle characteristics, a large aperture, miniaturization, and a small head design.

[0118] Specifically, the parameter values ​​of the small projection lens in this embodiment are shown in Table 4 below:

[0119] Table 4

[0120]

[0121]

[0122] like Figure 7 As shown, the surface number S0 represents the object surface, the surface numbers S1, S3, S5, S7, S9, S11, S13, S15, S17, S18, S20, S22, S24 to S26 represent the object side surfaces of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, the ninth lens L9, the tenth lens L10, the eleventh lens L11, the galvanometer L12, the prism L13 and the cover glass CG, and the surface numbers S2, S4, S6 , S8, S10, S12, S14, S16, S18, S19, S21, S23, S25 to S27 respectively represent the image side surfaces of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, the ninth lens L9, the tenth lens L10, the eleventh lens L11, the galvanometer L12, the prism L13 and the cover glass CG. The cemented surfaces of the cemented lens group are regarded as one surface. STO represents the aperture stop. The surface number S28 represents the image plane IMA.

[0123] Figure 8 The optical system includes a longitudinal spherical aberration diagram (LONGITUD INAL SPHERICAL ABER.), which shows the deviation of the convergent focus of light of different wavelengths passing through the lens. The ordinate of the longitudinal spherical aberration diagram represents the normalized pupil coordinate (Normalized Pupil Coordinator) from the center of the pupil to the edge of the pupil, and the abscissa represents the distance from the image plane to the intersection of the light and the optical axis (unit: mm). As can be seen from the longitudinal spherical aberration diagram, the degree of deviation of the convergent focus of light of each wavelength in this embodiment tends to be consistent and is within 0.025mm. The diffuse speckle or color halo in the imaging image is effectively suppressed, and the difference between single wavelength and complex wavelength is small. Figure 8 Also included are astigmatic field curvature diagrams for the optical system, where the S curve represents sagittal field curvature at a wavelength of 520nm, and the T curve represents meridional field curvature at a wavelength of 520nm. As can be seen from the diagram, the optical system's field curvature is within 0.025mm, and both field curvature and astigmatism are well corrected across all fields of view, resulting in sharp images at the center and edges of the field of view. Figure 8 The optical system's distortion diagram (DISTORTION) is also included. As can be seen from the diagram, optical distortion is within -1%, and image deformation caused by the main beam is minimal, demonstrating excellent imaging quality. In summary, the optical system's longitudinal spherical aberration, field curvature, and distortion are all well controlled, resulting in excellent imaging quality.

[0124] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0125] The above-described embodiments merely represent specific and detailed examples of the present application and should not be construed as limiting the scope of the utility model patent. It should be noted that a person skilled in the art may make various modifications and improvements without departing from the scope of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A small projection lens, characterized in that: The miniature projection lens comprises a first lens (L1) with positive focal power, a second lens (L2) with negative focal power, a third lens (L3) with negative focal power, a fourth lens (L4) with positive focal power, a fifth lens (L5) with positive focal power, a stop (STO), a sixth lens (L6) with positive focal power, a seventh lens (L7) with negative focal power, an eighth lens (L8) with positive focal power, a ninth lens (L9) with negative focal power, a tenth lens (L10) with positive focal power, and an eleventh lens (L11) with positive focal power, which are sequentially arranged along an optical axis. The small projection lens also meets the following conditions: 9.5≤f≤10.5;58≤OAL≤72; Wherein, f is the effective focal length of the small projection lens, in mm; OAL is the on-axis distance from the object side of the first lens (L1) to the image side of the eleventh lens (L11), in mm.

2. The small projection lens according to claim 1, wherein: The small projection lens also meets the following conditions: Where D is the entrance pupil diameter, in mm.

3. The small projection lens according to claim 1, wherein: The small projection lens also meets the following conditions: Wherein, SD1 is the marginal ray height on the object side of the first lens (L1), and SD11 is the marginal ray height on the image side of the eleventh lens (L11).

4. The small projection lens according to claim 1, wherein: The small projection lens also meets the following conditions: 6≤th4+th5+th11≤10 Wherein, th4 is the median thickness of the fourth lens (L4), th5 is the median thickness of the fifth lens (L5), and th11 is the median thickness of the eleventh lens (L11), and the unit is mm.

5. The small projection lens according to claim 1, wherein: The small projection lens also meets the following conditions: 110≤abv6+abv8≤160 Wherein, abv6 is the Abbe number of the sixth lens (L6), and abv8 is the Abbe number of the eighth lens (L8).

6. The small projection lens according to claim 1, wherein: The small projection lens also meets the following conditions: Wherein, f1 is the effective focal length of the first lens (L1), f2 is the effective focal length of the second lens (L2), and f3 is the effective focal length of the third lens (L3), and the unit is mm.

7. The small projection lens according to claim 1, wherein: The small projection lens also meets the following conditions: -0.85% ≤ DIST ≤ -0.1%; RI ≥ 60%; Among them, FOV is the full field of view angle of the maximum field of view, DIST is the maximum optical distortion from the center to the edge of the field of view, and RI is the relative illumination of the small projection lens on the image plane.

8. The small projection lens according to claim 1, wherein: The small projection lens further comprises a galvanometer mirror (L12) and a prism (L13) arranged in sequence along the optical axis direction, wherein the galvanometer mirror (L12) and the prism (L13) are located between the eleventh lens (L11) and the image plane.

9. The small projection lens according to claim 1, wherein: The small projection lens also meets the following conditions: Wherein, f4 is the effective focal length of the fourth lens (L4), in mm, R41 is the radius of curvature of the object side surface of the fourth lens (L4), and R42 is the radius of curvature of the image side surface of the fourth lens (L4), in mm.

10. The small projection lens according to any one of claims 1 to 9, wherein: The small projection lens also meets the following conditions: CRA≤2.4°,20≤FFL≤30 Wherein, CRA is the maximum incident angle of the small projection lens on the image plane, and FFL is the on-axis distance from the image side surface of the eleventh lens (L11) to the image plane, in mm.

Images