Small projection lens

Abstract

The invention 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 invention 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 are mainly in-vehicle TVs, but they are limited by the space and safety in the car, and the size of in-vehicle TVs is relatively small, which cannot meet the more diversified and immersive entertainment interaction needs; projection equipment can project a huge picture in a small space, which is a better solution; but traditional projectors are too large and cannot meet the stringent use requirements such as high and low temperatures in the car, which hinders the application of projection equipment in the in-vehicle space. Summary of the invention

[0003] The purpose of the present invention is to propose a small projection lens in view of the above problems. The lens has a small size, a suitable projection distance, a small projection ratio, a large aperture, can match a variety of DMD chips, and provide sufficient projection brightness and size. The projection picture is clear and sharp, the contrast is high, and the color reproduction is accurate. At the same time, it meets the stringent usage requirements under vehicle-mounted environmental conditions of -40℃ ~ +85℃.

[0004] To achieve the above object, the technical solution adopted by the present invention is:

[0005] A small projection lens provided by the present invention comprises 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 direction;

[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 axial 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, and the unit is 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 which are sequentially arranged along the optical axis direction, 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 axial distance from the image side surface of the eleventh lens to the image plane, in mm.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] This small projection lens adopts eleven lenses and is small in size, which reduces costs while ensuring image quality. The lens structure is compact by reasonably distributing the optical focal length. The total length of the lens is within 72mm, and the projection ratio TR range is 1.28-1.36. Various aberrations are corrected to improve edge image quality, thereby improving image quality. The maximum aperture can reach F1.64, which enables the lens to have a higher light output capacity. At the same time, the complementary materials are reasonably set so that the lens does not defocus in environmental conditions of -40℃~+85℃. The all-glass lens architecture can further expand the high temperature environment to 105℃, and the working performance is more stable. It can adapt to the 0.33" DMD chip with an offset of 110%, with high pixels and better image quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a schematic diagram of the structure of a small projection lens according to Embodiment 1 of the present invention;

[0039] Figure 2 The longitudinal spherical aberration diagram, astigmatism diagram and distortion diagram of the small projection lens in Example 1 of the present invention are shown;

[0040] Figure 3 This is a schematic diagram of the structure of a small projection lens according to Embodiment 2 of the present invention;

[0041] Figure 4 The longitudinal spherical aberration diagram, astigmatism diagram and distortion diagram of the small projection lens according to Example 2 of the present invention;

[0042] Figure 5 This is a schematic diagram of the structure of a small projection lens according to Embodiment 3 of the present invention;

[0043] Figure 6 The longitudinal spherical aberration diagram, astigmatism diagram and distortion diagram of the small projection lens in Example 3 of the present invention are shown;

[0044] Figure 7This is a schematic diagram of the structure of a small projection lens according to Embodiment 4 of the present invention;

[0045] Figure 8 Graphs showing longitudinal spherical aberration, astigmatism and distortion of the small projection lens according to Example 4 of the present invention.

[0046] Explanation of the accompanying drawings: 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 the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work 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 those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0049] A small projection lens, comprising 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 sequentially arranged along an optical axis direction;

[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 axial 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 sequentially arranged along the optical axis. The first lens L1 has a positive optical focal length, which provides sufficient light height for the edge field of view, is conducive to reducing the optical distortion of the edge, and provides a solution for a small front aperture; the second lens L2 with a negative optical focal length can quickly compress the light height, and cooperate with the first lens L1 to reduce the head size; the third lens L3 with a negative optical focal length shares the optical 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 with a positive optical focal length has a concave object side surface and a convex image side surface, which is in a meniscus shape. The convex surface has a higher light height, which provides a certain field curvature compensation for the system, making the optical system MTF highly concentrated; the fifth lens L5 with positive focal length connects the front and rear lens groups (for example, 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 of the edge field of view, ensure the brightness of the edge while reducing the main light angle of the lens, so that the lens can better match the projected optical system; the sixth lens L6 with positive focal length has a large Abbe number, which can reduce the chromatic aberration introduced into 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, the ninth lens L9, etc.) form a chromatic aberration complementary relationship and a spherical aberration complementary relationship; the ninth lens L9 with negative optical power and the tenth lens L10 with positive optical power form a doublet lens, or also form a triplet lens with the eighth lens L8, which can greatly reduce the overall chromatic aberration of the system, ensure the low level of axial chromatic aberration and vertical chromatic aberration, and achieve simultaneous clarity of monochromatic light and mixed color light; the eleventh lens L11 with positive optical power has a higher refractive index and a flat surface, which is helpful to reduce spherical aberration and correct the incident angle of the principal light.

[0054] And the f value of the small projection lens can be: 9.87, 9.86, 10.258, 10.268, 10.45, 9.3, in mm. If the above conditional formula is met, the 0.33DMD chip with Offset 110% is matched. Offset is the offset of the DMD chip relative to the optical axis, which can make the lens have wide-angle characteristics and a wide viewing angle, and can project the required frame at a short distance; if the upper limit of the range is exceeded, the lens angle is reduced and the frame is reduced; if the lower limit of the range is lowered, the lens angle increases, and the lens needs to be designed more complexly, and the demand for miniaturization and low cost is not met. In addition, the OAL value can be: 62.4, 61.4, 68.5, 67.8, 70.3, 60.6, in mm. If the above conditional formula is met, the lens has a small volume and compact space, which meets the demand for miniaturization; if the upper limit is exceeded, the demand for miniaturization is not met; if the lower limit is lowered, the lens space is compressed, which is not conducive to improving clarity, and the material is more expensive, which easily leads to excessive cost. After being assembled with the lens barrel, the small projection lens can better adapt to the vehicle-mounted vibration environment and has good stability.

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

[0056]

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

[0058] Specifically, the f / D value can be: 1.7, 1.8, 2.0, 2.05, 1.65, 1.9. If the above conditions are met, the lens has a larger aperture, which can meet the needs of low-cost and low-light projection equipment, as well as high-light projection equipment, so that the lens has a wide range of use and meets the needs of most projection scenes on the market.

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

[0060]

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

[0062] Specifically, the values ​​of SD1 / SD11 can be: 1.39, 1.43, 1.31, 1.264, 1.202, 1.41. When the above conditional formula is met, the aperture of the first lens L1 and the aperture of the eleventh lens L11 are very close, so that the diameter of the head and tail of the structure can be basically the same, which is conducive to the overall miniaturization design of the projection, and also helps to reduce the exposed area of ​​the projection, improve the integration, reduce the discomfort of exposure, and improve the aesthetics of the projection equipment in the car space. If it exceeds the upper limit, the head size is too large, which reduces the aesthetics of the application; if it is lower than the lower limit, the head size is too small, the design is difficult, 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 one embodiment, the small projection lens further 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, and the unit is mm.

[0066] Specifically, the values ​​of th4+th5+th11 can be: 9.59, 8.38, 7.5, 7.9, 7.2, 6.8, in mm. Due to the distribution of optical power, the fourth lens L4, the fifth lens L5 and the eleventh lens L11 are often made of materials with a relatively high refractive index. Due to their own characteristics, the materials with a high refractive index have a low short-wave transmittance. In order to enhance the short-wave transmittance of the lens, the thickness of the high refractive index material must be strictly controlled. When the above conditional formula is met, the overall thickness of the high refractive index material can be controlled within a reasonable range to ensure that the difference between the short-wave transmittance and the long-wave transmittance of the lens is small, and the color temperature deviation problem is avoided; if the upper limit value is exceeded, the thickness of the fourth lens L4, the fifth lens L5 and the eleventh lens L11 is too thick, which may easily cause the short-wave transmittance to be low, affecting the color temperature and brightness of the projected image; if the lower limit value is exceeded, the thickness of the lens is too thin, which is not conducive to processing.

[0067] In one embodiment, the small projection lens further 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, 145.26. The sixth lens L6 and the eighth lens L8 are low refractive index and high Abbe number materials, and the material range is close to the negative dndt material. Dndt is the refractive index temperature coefficient. If the above conditional formula is met, the sixth lens L6 and the eighth lens L8 can select a suitable negative dndt material to compensate for the expansion and contraction of the excessive back focus at high and low temperatures, so that the lens completes the optical athermal design, which can meet the vehicle-mounted temperature range of -40℃ to 85℃, and when the plastic lens is not set, the high temperature can cover up to 105℃. Beyond the limited range, the material selection cannot meet the high and low temperature compensation requirements.

[0071] In one embodiment, the small projection lens further satisfies 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, and the unit is mm.

[0074] Specifically, the values ​​of f1 / (f2+f3) can be: -1.05, -1.09, -1.36, -1.33, -1.25, -1.13. If the above conditional formula is met, the first lens L1, the second lens L2 and the third lens L3 are a combination of positive and negative focal lengths, and the effective focal length is limited to a reasonable range. The positive and negative combination lens group can be used to achieve a small aperture and low distortion effect, reduce the introduction of aberrations, and improve overall clarity. If the range is exceeded, the focal length is uneven, and it is not easy to achieve a small head solution.

[0075] In one embodiment, the small projection lens further satisfies 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, -92.3, in degrees / %. When the above conditional formula is met, in the case of a wide-angle FOV, the maximum optical distortion can be controlled within a reasonable range, and it is more appropriate for full-glass compensation distortion, so that the lens is within a reasonable range of FOV and DIST, ensuring low deformation of the projection size and frame. In addition, DIST can be: -0.75%, -0.76%, -0.6%, -0.65%, -0.55%, -0.5%. When the above conditional formula is met, the optical distortion of the lens is within a reasonable range, and the distortion of the projection TV is less than 0.5%. The human eye can hardly perceive the deformation of the picture, which helps to improve comfort; exceeding this range, the optical distortion is too large, the deformation of the projection picture becomes larger, and it may cause discomfort in observation. RI values ​​can be: 65%, 68%, 70%, 72%, 75%, 78%. If the above conditions are met, good illumination uniformity can be guaranteed within the range of Offset100%, and dark corners can be avoided due to low illumination at the edges. If the range is exceeded, the relative illumination is too low, dark corners are more likely to occur, affecting the viewing comfort.

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

[0082] Among them, the galvanometer G5 is used to perform high-frequency vibration in different directions, so that the image expands the pixel range on the original pixel for a short time, and uses the visual persistence effect to increase the pixels recognized by the human eye, thereby improving the projection resolution; the prism G6 is an equivalent flat plate, which is used to complete the light aggregation for different light source combinations, such as providing a suitable reflection angle and refraction angle for each light. It is a well-known technology for those in the field and will not be repeated here.

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

[0084]

[0085] Wherein, f4 is the effective focal length of the fourth lens L4, and the unit is 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, and the unit is mm.

[0086] Specifically, the value of f4 / f can be: 2.4, 4.3, 5.5, 6.4, 7.6, 8.3, which satisfies the above conditional formula. The fourth lens L4 has a positive optical power and a relatively small optical power in the lens, which can quickly raise the light height and reduce the tolerance sensitivity of the fourth lens L4 and the fifth lens L5. Further, R41 / R42 can be: 1.2, 3.4, 6.3, 8.2, 10.8, 13.7. The surface curvature direction of the object side and the image side of the fourth lens L4 is the same, which can increase the light height difference between the concave surface and the convex surface, provide sufficient field curvature compensation, reduce the field curvature and astigmatism of the system, and unify the resolution level of the center and the four corners of the projection screen; exceeding this range will increase the optical power of the fourth lens L4, or change the optical power sign, resulting in concentrated lens sensitivity, which is not conducive to mass production.

[0087] In one embodiment, the small projection lens further satisfies 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 axial 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 to ensure that the lens is aligned with the light output direction, improve the light output efficiency from the center to the edge of the picture, and avoid 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 projection optical machines; if it exceeds the upper limit, the back focus is too large, which increases 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 optical path and the heat dissipation of the projection optical machine, affecting the user experience.

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

[0092] Embodiment 1:

[0093] like Figure 1As 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 protective glass CG arranged in sequence along the optical axis, wherein the ninth lens L9 and the tenth lens L10 form a double cemented lens. The effective focal length of this optical system is f=10.268mm, the aperture number Fno=2.0, the field of view angle is 58.25°, and the axial distance OAL from the object side of the first lens L1 to the image side of the eleventh lens L11 is 67.8mm; it can be seen that this optical system can achieve wide-angle characteristics, large aperture, miniaturization and 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 in the figure, 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 protective 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 surface of the cemented lens group is regarded as one surface, STO represents an aperture stop, and the surface number S28 represents the image surface IMA.

[0099] Figure 2The longitudinal spherical aberration diagram (LONGITUD INAL SPHERICAL ABER.) of the optical system indicates the deviation of the convergent focus of light of different wavelengths after passing through the lens. The ordinate of the longitudinal spherical aberration diagram indicates the normalized pupil coordinate (Normalized Pupil Coordinator) from the center of the pupil to the edge of the pupil, and the abscissa indicates the distance from the image plane to the intersection of the light and the optical axis (in mm). It can be seen from the longitudinal spherical aberration diagram that 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 spots or color halos in the imaging picture are effectively suppressed, and the difference between single wavelength and complex wavelength is small. Figure 2 It also includes the field curvature diagram of the optical system (ASTIGMATIC FIELD CURVES), where the S curve represents the sagittal field curvature at a wavelength of 520nm, and the T curve represents the meridian field curvature at a wavelength of 520nm. As can be seen from the figure, the field curvature of the optical system is within 0.025mm, the field curvature and astigmatism of each field of view are well corrected, and the center and edge of the field of view have clear imaging. Figure 2 It also includes the distortion diagram of the optical system (DISTORTION). It can be seen from the figure that the optical distortion is within -1%, the image deformation caused by the main beam is small, and the imaging quality of the system is excellent. In summary, the longitudinal spherical aberration, field curvature and distortion of the optical system are well controlled, and have good imaging quality.

[0100] Embodiment 2:

[0101] like Figure 3 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 protective glass CG arranged in sequence along the optical axis, wherein the eighth lens L8, the ninth lens L9 and the tenth lens L10 form a triplet lens. The effective focal length of this optical system is f=9.87mm, the aperture number Fno=1.7, the field of view is 60.13°, and the axial distance OAL from the object side of the first lens L1 to the image side of the eleventh lens L11 is 62.4mm; it can be seen that this optical system can achieve wide-angle characteristics, large aperture, miniaturization and 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 in the figure, 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 protective 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 surface of the cemented lens group is regarded as one surface, STO represents an aperture stop, and the surface number S27 represents the image surface IMA.

[0107] Figure 4 The longitudinal spherical aberration diagram (LONGITUD INAL SPHERICAL ABER.) of the optical system indicates the deviation of the convergent focus of light of different wavelengths after passing through the lens. The ordinate of the longitudinal spherical aberration diagram indicates the normalized pupil coordinate (Normalized Pupil Coordinator) from the center of the pupil to the edge of the pupil, and the abscissa indicates the distance from the image plane to the intersection of the light and the optical axis (in mm). It can be seen from the longitudinal spherical aberration diagram that 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 spots or color halos in the imaging picture are effectively suppressed, and the difference between single wavelength and complex wavelength is small. Figure 4 It also includes the field curvature diagram of the optical system (ASTIGMATIC FIELD CURVES), where the S curve represents the sagittal field curvature at a wavelength of 520nm, and the T curve represents the meridian field curvature at a wavelength of 520nm. As can be seen from the figure, the field curvature of the optical system is within 0.025mm, the field curvature and astigmatism of each field of view are well corrected, and the center and edge of the field of view have clear imaging. Figure 4 It also includes the distortion diagram of the optical system (DISTORTION). It can be seen from the figure that the optical distortion is within -1%, the image deformation caused by the main beam is small, and the imaging quality of the system is excellent. In summary, the longitudinal spherical aberration, field curvature and distortion of the optical system are well controlled, and have good imaging quality.

[0108] Embodiment 3:

[0109] like Figure 5 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 protective glass CG arranged in sequence along the optical axis, wherein the ninth lens L9 and the tenth lens L10 form a double cemented lens. The effective focal length of this optical system is f=9.86mm, the aperture number Fno=1.8, the field of view is 60.14°, and the axial 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 seen that this optical system can achieve wide-angle characteristics, large aperture, miniaturization and small head design.

[0110] Specifically, the parameter values ​​of the small projection lens in this embodiment are shown in Table 3 below:

[0111] Table 3

[0112]

[0113]

[0114] like Figure 5 As shown in the figure, 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 protective 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 surface of the cemented lens group is regarded as one surface, STO represents an aperture stop, and the surface number S28 represents the image surface IMA.

[0115] Figure 6The longitudinal spherical aberration diagram (LONGITUD INAL SPHERICAL ABER.) of the optical system indicates the deviation of the convergent focus of light of different wavelengths after passing through the lens. The ordinate of the longitudinal spherical aberration diagram indicates the normalized pupil coordinate (Normalized Pupil Coordinator) from the center of the pupil to the edge of the pupil, and the abscissa indicates the distance from the image plane to the intersection of the light and the optical axis (in mm). It can be seen from the longitudinal spherical aberration diagram that 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 spots or color halos in the imaging picture are effectively suppressed, and the difference between single wavelength and complex wavelength is small. Figure 6 It also includes the field curvature diagram of the optical system (ASTIGMATIC FIELD CURVES), where the S curve represents the sagittal field curvature at a wavelength of 520nm, and the T curve represents the meridian field curvature at a wavelength of 520nm. As can be seen from the figure, the field curvature of the optical system is within 0.025mm, the field curvature and astigmatism of each field of view are well corrected, and the center and edge of the field of view have clear imaging. Figure 6 It also includes the distortion diagram of the optical system (DISTORTION). It can be seen from the figure that the optical distortion is within -1%, the image deformation caused by the main beam is small, and the imaging quality of the system is excellent. In summary, the longitudinal spherical aberration, field curvature and distortion of the optical system are well controlled, and have good imaging quality.

[0116] Embodiment 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 protective glass CG arranged in sequence along the optical axis, wherein the ninth lens L9 and the tenth lens L10 form a double cemented lens. The effective focal length of this optical system is f=10.258mm, the aperture number Fno=2.0, the field of view is 58.16°, and the axial distance OAL from the object side of the first lens L1 to the image side of the eleventh lens L11 is 68.5mm; it can be seen that this optical system can achieve wide-angle characteristics, large aperture, miniaturization and 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 in the figure, 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 protective 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 surface of the cemented lens group is regarded as one surface, STO represents an aperture stop, and the surface number S28 represents the image surface IMA.

[0123] Figure 8 The longitudinal spherical aberration diagram (LONGITUD INAL SPHERICAL ABER.) of the optical system indicates the deviation of the convergent focus of light of different wavelengths after passing through the lens. The ordinate of the longitudinal spherical aberration diagram indicates the normalized pupil coordinate (Normalized Pupil Coordinator) from the center of the pupil to the edge of the pupil, and the abscissa indicates the distance from the image plane to the intersection of the light and the optical axis (in mm). It can be seen from the longitudinal spherical aberration diagram that 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 spots or color halos in the imaging picture are effectively suppressed, and the difference between single wavelength and complex wavelength is small. Figure 8 It also includes the field curvature diagram of the optical system (ASTIGMATIC FIELD CURVES), where the S curve represents the sagittal field curvature at a wavelength of 520nm, and the T curve represents the meridian field curvature at a wavelength of 520nm. As can be seen from the figure, the field curvature of the optical system is within 0.025mm, the field curvature and astigmatism of each field of view are well corrected, and the center and edge of the field of view have clear imaging. Figure 8 It also includes the distortion diagram of the optical system (DISTORTION). It can be seen from the figure that the optical distortion is within -1%, the image deformation caused by the main beam is small, and the imaging quality of the system is excellent. In summary, the longitudinal spherical aberration, field curvature and distortion of the optical system are well controlled, and have good imaging quality.

[0124] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described 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 only express the more specific and detailed embodiments described in this application, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of this application, which all belong to the protection scope of this application. Therefore, the protection scope of the patent in this application shall be based on the attached claims.

Claims

1. A small projection lens, characterized in that: The 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, 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 direction; 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 axial distance from the object side surface of the first lens (L1) to the image side surface of the eleventh lens (L11), in mm.

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

3. The small projection lens as claimed in claim 1, characterized in that: 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 as claimed in claim 1, characterized in that: The small projection lens also meets the following conditions: 6≤th4+th5+th11≤10 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), and the unit is mm.

5. The small projection lens as claimed in claim 1, characterized in that: 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 as claimed in claim 1, characterized in that: 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 as claimed in claim 1, characterized in that: 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 as claimed in claim 1, characterized in that: The small projection lens further comprises a galvanometer mirror (L12) and a prism (L13) which are sequentially arranged along the optical axis direction, and the galvanometer mirror (L12) and the prism (L13) are located between the eleventh lens (L11) and the image plane.

9. The small projection lens as claimed in claim 1, characterized in that: 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, characterized in that: 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 axial distance from the image side surface of the eleventh lens (L11) to the image plane, in mm.

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