A zoom lens with a small volume

Abstract

The present invention provides a zoom lens with a small volume, relating to the technical field of projection zoom lenses. The zoom lens includes a main lens group and a relay lens group. The total length of the main lens group is less than or equal to 110 millimeters. Along the optical axis direction from the object side to the image side, the main lens group includes: a light valve; a first lens with a convex object side and a concave image side; a second lens with convex object and image sides and spherical surfaces; a triplet lens with a double-convex-double-concave-double-convex structure; a sixth lens with a convex object side and a concave image side; a diaphragm; a seventh lens with convex object and image sides and spherical surfaces; an eighth lens with a concave object side and a flat image side; a ninth lens with a concave object side and a convex image side. The relay lens group is located on the side of the diaphragm closer to the seventh lens. Through the compact design of the main lens group and the modular configuration of the relay lens group, the problems of large volume, high cost, insufficient image quality and lifespan of traditional zoom lenses are systematically solved.

Description

Technical Field

[0001] The present invention relates to the technical field of projection zoom lenses, and in particular to a zoom lens with a small volume. Background Art

[0002] In recent years, with the wide application of projection devices in home entertainment, business meetings, and educational scenarios, users' requirements for the performance of projection systems have been increasing day by day. There is an urgent need for features such as small volume, high image quality, and variable zoom. However, the existing projection lens designs face significant technical bottlenecks in meeting the above requirements, specifically manifested as the following problems: the cumbersome operation of fixed-focus projection systems, the cost and volume issues of zoom projection systems, and insufficient lifespan and durability.

[0003] Based on the above technical problems, there is an urgent need for a zoom lens solution that takes into account small volume, high image quality, long lifespan, and controllable cost. Summary of the Invention

[0004] In view of the above problems existing in the prior art, the present invention provides a zoom lens with a small volume, including a main lens group and a relay lens group. The total length of the main lens group is less than or equal to 110 millimeters. The main lens group, along the optical axis direction from the object side to the image side, successively includes:

[0005] A light valve;

[0006] A first lens with a convex object side and a concave image side, the optical power of the first lens being positive, and the material being glass;

[0007] A second lens with both the object side and the image side being convex and spherical, the optical power of the second lens being positive;

[0008] A triplet lens having a double-convex - double-concave - double-convex structure, the optical powers of the triplet lens being positive, negative, and positive in sequence;

[0009] A sixth lens with a convex object side and a concave image side, the optical power of the sixth lens being negative;

[0010] A diaphragm;

[0011] A seventh lens with both the object side and the image side being convex and spherical, the optical power of the seventh lens being positive;

[0012] An eighth lens with a concave object side and a flat image side, the optical power of the eighth lens being negative;

[0013] A ninth lens with a concave object side and a convex image side, the optical power of the ninth lens being positive, and the material being glass;

[0014] The relay lens group is located on the side of the diaphragm closer to the seventh lens and includes at least two lenses.

[0015] In some implementations, the relay lens group includes a first relay lens group. The first relay lens group is located between the seventh lens and the eighth lens and includes a first relay lens, a second relay lens, a third relay lens, and a fourth relay lens arranged in sequence from the object side to the image side. The object side of the first relay lens is concave and the image side is flat. The object side of the second relay lens is concave and the image side is convex. The object side of the third relay lens is concave and the image side is convex. The object side of the fourth relay lens is convex and the image side is also convex.

[0016] In some implementations, the focal length of the zoom lens is greater than or equal to 7.5 mm and less than or equal to 7.9 mm, and the resolution is greater than or equal to 116 lp / mm and less than or equal to 120 lp / mm.

[0017] In some implementations, the relay lens group includes a second relay lens group. The second relay lens group is located on the side of the ninth lens away from the diaphragm and includes a fifth relay lens and a sixth relay lens arranged in sequence from the object side to the image side. The object side of the fifth relay lens is concave and the image side is convex. The object side of the sixth relay lens is concave and the image side is convex.

[0018] In some implementations, the focal length of the zoom lens is greater than or equal to 12.2 mm and less than or equal to 12.6 mm, and the resolution is greater than or equal to 116 lp / mm and less than or equal to 120 lp / mm.

[0019] In some implementations, the triplet lens includes a third lens, a fourth lens, and a fifth lens arranged in sequence from the object side to the image side. The object side and the image side of the third lens are both convex. The object side and the image side of the fourth lens are both concave. The object side and the image side of the fifth lens are both convex.

[0020] In some implementations, the material of the eighth lens is plastic.

[0021] In some implementations, the distance from the plane where the light valve is located to the vertex of the object side of the first lens is denoted as BFL, and the distance from the vertex of the object side of the first lens to the vertex of the image side of the ninth lens is denoted as L1, where 0.05 < BFL / L1 < 0.63.

[0022] In some implementations, it further includes an illumination prism and an image offset mirror arranged in sequence from the object side to the image side between the light valve and the first lens. The distance from the plane where the object side of the illumination prism is located to the vertex of the image side of the ninth lens is denoted as L2, and the total focal length of the zoom lens is denoted as F, where 0.007 < F / L2 < 0.8.

[0023] In some implementations, the projection ratio of the zoom lens is greater than or equal to 0.8 and less than or equal to 1.5.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: Through the compact design of the main lens group and the modular configuration of the relay lens group, the problems of large volume, high cost, insufficient image quality and short lifespan of traditional zoom lenses are systematically solved. The total length of the main lens group is ≤ 110 mm. Aberrations are balanced through the positive and negative alternating optical power distribution (such as positive, positive, positive, negative, positive, negative, positive, negative, positive), and the three-glue lens integrates the chromatic aberration correction function, reducing the number of lenses; the aperture stop is fixed inside the main lens group to avoid image quality fluctuations caused by movement and compress the lateral space. The relay lens group is located behind the aperture stop and contains at least two lenses. The projection ratio is adjusted by replacing different relay lens groups (non-mechanical movement), eliminating the complex zoom structure and reducing the assembly cost. The key lens design enhances performance: The first lens (convex - concave) and the ninth lens (concave - convex) are made of glass material to improve high temperature resistance and wear resistance, extending the lifespan; the sixth lens (negative optical power) corrects spherical aberration, the eighth lens (concave - flat) simplifies the process and suppresses image plane curvature, and the seventh lens (double convex spherical) optimizes the light convergence. The above structures work together synergistically, enabling the lens to achieve a high resolution of 118 lp / mm while reducing the volume, adapting to the screen size change from 50 to 150 inches, taking into account low cost, high image quality and long lifespan, and breaking through the technical bottleneck of traditional solutions. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0026] Figure 1a The following shows a schematic structural diagram of a zoom lens provided by an embodiment of the present invention.

[0027] Figure 1b Shown is Figure 1a a ray fan diagram of the zoom lens shown.

[0028] Figure 1c Shown is Figure 1a a SPOT diagram of the zoom lens shown.

[0029] Figure 1d Shown is Figure 1a an MTF diagram of the zoom lens shown.

[0030] Figure 1e Shown is Figure 1a a RI diagram of the zoom lens shown.

[0031] Figure 1f Shown is Figure 1a an MTF vs field of view diagram of the zoom lens shown.

[0032] Figure 2a The following is a schematic structural diagram of a zoom lens provided by another embodiment of the present invention.

[0033] Figure 2b is Figure 2a the light fan diagram of the zoom lens shown.

[0034] Figure 2c is Figure 2a the SPOT diagram of the zoom lens shown.

[0035] Figure 2d is Figure 2a the MTF diagram of the zoom lens shown.

[0036] Figure 2e is Figure 2a the RI diagram of the zoom lens shown.

[0037] Figure 2f is Figure 2a the MTF vs field of view diagram of the zoom lens shown.

[0038] Figure 3a The following is a schematic structural diagram of a zoom lens provided by another embodiment of the present invention.

[0039] Figure 3b is Figure 3a the light fan diagram of the zoom lens shown.

[0040] Figure 3c is Figure 3a the SPOT diagram of the zoom lens shown.

[0041] Figure 3d is Figure 3a the MTF diagram of the zoom lens shown.

[0042] Figure 3e is Figure 3a the RI diagram of the zoom lens shown.

[0043] Figure 3f is Figure 3a the MTF vs field of view diagram of the zoom lens shown.

[0044] Reference numerals: light valve 10; diaphragm 50; first lens 1; second lens 2; third lens 3; fourth lens 4; fifth lens 5; sixth lens 6; seventh lens 7; eighth lens 8; ninth lens 9; triplet lens 345; first relay lens 201; second relay lens 202; third relay lens 203; fourth relay lens 204; fifth relay lens 205; sixth relay lens 206; illumination prism 30; image offset mirror 40. Detailed implementation manners

[0045] To make the objectives, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope protected by the present invention.

[0046] The specific embodiments of the present invention will be described below.

[0047] Figure 1a The following shows a schematic structural diagram of a zoom lens provided by an embodiment of the present invention. As Figure 1a shown, the present invention provides a zoom lens with a small volume, which includes a main lens group and a relay lens group. The total length of the main lens group is less than or equal to 110 millimeters. Along the optical axis direction from the object side to the image side, the main lens group includes:

[0048] A light valve 10;

[0049] A first lens 1 with a convex object side and a concave image side. The optical power of the first lens 1 is positive, and the material is a glass material;

[0050] A second lens 2 with convex object and image sides and spherical surfaces. The optical power of the second lens 2 is positive;

[0051] A triplet lens 345 with a double-convex-double-concave-double-convex structure. The optical powers of the triplet lens 345 are positive, negative, and positive in sequence;

[0052] A sixth lens 6 with a convex object side and a concave image side. The optical power of the sixth lens 6 is negative;

[0053] A diaphragm 50;

[0054] A seventh lens 7 with convex object and image sides and spherical surfaces. The optical power of the seventh lens 7 is positive;

[0055] An eighth lens 8 with a concave object side and a flat image side. The optical power of the eighth lens 8 is negative;

[0056] A ninth lens 9 with a concave object side and a convex image side. The optical power of the ninth lens 9 is positive, and the material is a glass material;

[0057] The relay lens group is located on the side of the diaphragm 50 close to the seventh lens 7 and includes at least two lenses.

[0058] This embodiment relates to a small-sized zoom lens. The core lies in the collaborative design of the main lens group and the relay lens group to achieve the comprehensive goals of volume compression, zoom flexibility, and high image quality. The total length of the main lens group is strictly limited to no more than 110 mm, and successively includes a light valve 10, a first lens 1 to a ninth lens 9 from the object side to the image side. The optical power distribution of each lens is positive, positive, positive, negative, positive, negative, positive, negative, positive. The light valve 10 serves as the light source input end to control the light entering the main lens group; the first lens 1 is a convex-concave structure made of glass with a positive optical power. The convex object side design can quickly converge the light, and the concave image side is used to initially correct spherical aberration. The second lens 2 is a double-convex spherical lens with a positive optical power as well, further converging the light and balancing field curvature. The triplet lens 345 consists of the third to fifth lenses 5 with optical powers of positive, negative, and positive in sequence. Its double-convex-double-concave-double-convex structure is integrated through a gluing process, effectively correcting chromatic aberration and reducing the number of lenses, avoiding volume expansion caused by the gaps between discrete lenses in traditional designs. The sixth lens 6 is a convex-concave structure with a negative optical power, used to offset the aberration accumulated by the positive optical power in the previous section and shorten the back focal length at the same time. The aperture stop 50 is fixed behind the sixth lens 6 to control the beam aperture to stabilize the optical path. The seventh lens 7 is a double-convex spherical lens with a positive optical power, designed close to the aperture stop 50 to converge the light and correct astigmatism. The eighth lens 8 is a concave-planar structure with a negative optical power. The planar image side simplifies the processing technology, and the negative optical power balances the overshoot of the positive optical power in the previous section and suppresses image plane curvature. The ninth lens 9 is a concave-convex structure with a positive optical power. The glass material ensures the wear resistance at the screen end. The convex image side optimizes the incident angle of marginal rays to reduce distortion. The relay lens group is located behind the aperture stop 50 (close to the seventh lens 7 side), includes at least two lenses, and realizes the projection ratio adjustment by replacing different relay lens groups without a complex mechanical moving structure.

[0059] The limitation of the total length of the main lens group combined with the alternating distribution of optical power significantly compresses the longitudinal space; the triplet lens 345 integrates the chromatic aberration correction function and reduces the number of lenses; the fixed design of the aperture stop 50 avoids occupying the lateral space; the modular configuration of the relay lens group reduces the zoom complexity. The two end lenses (the first lens 1, the ninth lens 9) are made of glass material to improve high temperature resistance and wear resistance and extend the service life. The negative optical power designs of the sixth lens 6 and the eighth lens 8 cooperate to suppress spherical aberration and image plane curvature, ensuring the consistency of the resolution from the center to the edge.

[0060] Among them, the materials of the first lens 1 and the ninth lens 9 can be replaced with high-refractive-index glass to further shorten the optical total length; the minimum number of lenses in the relay lens group can be extended to three, provided that the optical power distribution meets the projection ratio adjustment requirements.

[0061] Reference Figure 1a, in some embodiments, the relay lens group includes a first relay lens group located between the seventh lens 7 and the eighth lens 8, and includes a first relay lens 201, a second relay lens 202, a third relay lens 203, and a fourth relay lens 204 arranged in sequence from the object side to the image side. The object side of the first relay lens 201 is concave and the image side is flat. The object side of the second relay lens 202 is concave and the image side is convex. The object side of the third relay lens 203 is concave and the image side is convex. The object side of the fourth relay lens 204 is convex and the image side is also convex.

[0062] This embodiment details the first configuration of the relay lens group (the first relay lens group), which is located between the seventh lens 7 and the eighth lens 8, and sequentially includes the first relay lens 201 to the fourth relay lens 204 from the object side to the image side. The first relay lens 201 has a concave - flat structure with a negative focal power, and the flat image side simplifies the processing and preliminarily diverges the light rays; the second relay lens 202 has a concave - convex structure with a positive focal power, which is used to converge the light rays and correct astigmatism; the third relay lens 203 has a concave - convex structure with a positive focal power, which further optimizes the light path convergence; the fourth relay lens 204 has a double - convex structure with a positive focal power, which finally outputs the light rays and balances the field curvature. The focal powers of the four lenses are sequentially distributed as negative, positive, positive, and positive. The front - placed negative - focal - power lens cancels the positive - focal - power accumulation in the latter part of the main lens group to avoid the amplification of aberration.

[0063] The first relay lens group achieves a low projection ratio (such as 0.8) through the combination of four lenses. The concave - flat lens reduces the processing difficulty, and the double - convex terminal lens ensures the light rays enter the screen smoothly, reducing the edge distortion. The focal power distribution of the four lenses coordinates with the main lens group to maintain a high resolution (116 - 120 lp / mm).

[0064] Among them, the second relay lens 202 can be replaced with a double - concave structure with a negative focal power. At this time, it is necessary to adjust the focal powers of the subsequent lenses to higher positive values to maintain the total focal power balance.

[0065] In some embodiments, the focal length of the zoom lens is greater than or equal to 7.5 mm and less than or equal to 7.9 mm, and the resolution is greater than or equal to 116 lp / mm and less than or equal to 120 lp / mm.

[0066] The focal length ranges of the main lens group and the first relay lens group are limited to 7.5 - 7.9 mm, and the resolution is 116 - 120 lp / mm. This range is achieved through the precise design of the lens curvature radius and the spacing: too small a focal length may cause excessive convergence of light rays and lead to spherical aberration, while too large a focal length reduces the zoom sensitivity; the lower limit of the resolution ensures clear details of the picture, and the upper limit avoids excessive correction and increases the process complexity.

[0067] The focal length of 7.5 - 7.9 mm balances the zoom range and the requirements for aberration control; the resolution of 116 - 120 lp / mm covers the mainstream projection resolution standard and is also compatible with manufacturing tolerances.

[0068] Taking Figure 1a the first relay lens group shown as an example, the projection ratio of the entire zoom lens is 0.8, the focal length is 7.7 mm, the resolution is 118 lp / mm, the projected image size is 20 to 190 inches, and the main projected size is 70 to 160 inches. Figures 1b to 1f For Figure 1a the image quality evaluation diagram of the zoom lens shown.

[0069] Specifically, Figure 1b the light ray fan diagram shows the light path distribution of light rays passing through the lens at different field angles, verifying the optical axis symmetry and the astigmatism correction effect. Figure 1b The degree of concentration of the light ray trajectories in it indicates the ability of the system to suppress astigmatism. There is no obvious divergence of the light rays in the edge field of view, indicating good field curvature control.

[0070] Figure 1c The SPOT diagram of

[0071] Figure 1d shows the spot shapes and sizes at different field positions. The spots are close to circular and the diameters are uniform, proving that the spherical aberration and coma are corrected sufficiently, and there is no obvious distortion or trailing in the edge field of view.

[0072] Figure 1e The MTF diagram (modulation transfer function) of

[0073] Figure 1f reflects the response ability of the lens to different spatial frequencies. The curve still maintains a high contrast at 118 lp / mm, indicating that the resolution meets the design requirements, and the decline of the MTF value from the center to the edge is small, indicating excellent image quality uniformity.

[0074] From Figures 1b to 1f it can be seen that at a low projection ratio (0.8), the zoom lens maintains a high resolution (118 lp / mm) and uniform image quality in the range of 70 - 160 inches, meeting the requirements for large - screen projection in a narrow space.

[0075] Figure 2a The following shows the structural schematic diagram of the zoom lens provided by another embodiment of the present invention. As Figure 2aAs shown, in some implementations, the relay lens group includes a second relay lens group. The second relay lens group is located on the side of the ninth lens 9 away from the aperture 50, and includes a fifth relay lens 205 and a sixth relay lens 206 arranged in sequence from the object side to the image side. The object side of the fifth relay lens 205 is concave and the image side is convex. The object side of the sixth relay lens 206 is concave and the image side is convex.

[0076] The second relay lens group is located on the side of the ninth lens 9 away from the aperture 50 and is composed of the fifth relay lens 205 and the sixth relay lens 206. The fifth relay lens 205 has a concave-convex structure with a negative focal power, initially diverging the light rays. The sixth relay lens 206 has a concave-convex structure with a positive focal power, converging the light rays and correcting distortion. The focal powers of the two lenses are distributed as negative and positive, adapting to the requirements of a high projection ratio (such as 1.5).

[0077] The negative-positive focal power distribution expands the projection ratio range. The concave-convex structure suppresses astigmatism, and the configuration of the two lenses simplifies the volume of the relay lens group.

[0078] In some implementations, the focal length of the zoom lens is greater than or equal to 12.2 mm and less than or equal to 12.6 mm, and the resolution is greater than or equal to 116 lp / mm and less than or equal to 120 lp / mm.

[0079] The focal lengths of the main lens group and the second relay lens group are limited to 12.2 - 12.6 mm, and the resolution is 116 - 120 lp / mm. This range ensures the stability of the optical path under a high projection ratio. If the focal length is too small, it is easy for the marginal light rays to escape. If it is too large, the total length of the lens will increase.

[0080] Taking Figure 2a the second relay lens group shown as an example, the projection ratio of the entire zoom lens is 1.5, the focal length is 12.4 mm, the resolution is 118 lp / mm, the projection screen size is 40 to 120 inches, and the main projection size is 50 to 150 inches. Figures 2b to 2f For Figure 2a the image quality evaluation diagram of the zoom lens shown.

[0081] Specifically, from Figure 2b the light fan diagram of the light rays, it can be seen that the light ray trajectories still maintain a compact distribution under a high projection ratio, indicating that the optical path stability is good in the long focal length state, and astigmatism or field curvature does not deteriorate due to the increase in the focal length.

[0082] From Figure 2c the SPOT diagram of [], it can be seen that the diameter of the light spot at the long focal length end is slightly larger than that at the short focal length end, but the shape is still close to a circle, and there is no obvious coma or distortion in the marginal field of view, indicating that the aberration correction scheme adapts to the requirements of different focal lengths.

[0083] From Figure 2dFrom the MTF graph, it can be seen that the contrast at 118 lp / mm is slightly lower than that in the low projection ratio state, but is still significantly higher than the industry standard (93 lp / mm), proving that the image quality in the telephoto mode has not significantly decreased and meets the requirements of high-resolution projection.

[0084] From Figure 2e From the RI graph, it can be seen that the edge illumination loss is about 20%, which is within the acceptable range, indicating that the lens can still maintain the uniformity of the picture brightness at a high projection ratio.

[0085] From Figure 2f From the MTF vs field of view graph, it can be seen that the MTF value of the central field of view is relatively high, and the MTF value of the edge field of view decreases slightly, but the overall trend is gentle, showing that the image quality transitions naturally in the telephoto mode without sudden change defects.

[0086] Figures 2b to 2f The applicability of the zoom lens at a high projection ratio (1.5) is verified. Especially in the range of 50 - 150 inches, the resolution and image quality stability are still better than those of traditional zoom lenses, making it suitable for long-distance projection scenarios.

[0087] Refer to Figure 1a 、 Figure 2a and Figure 3a In some implementation manners, the triplet lens 345 includes a third lens 3, a fourth lens 4, and a fifth lens 5 arranged in sequence from the object side to the image side. Both the object side and the image side of the third lens 3 are convex surfaces, both the object side and the image side of the fourth lens 4 are concave surfaces, and both the object side and the image side of the fifth lens 5 are convex surfaces.

[0088] The triplet lens 345 is composed of a third lens 3 (double convex surface, positive optical power), a fourth lens 4 (double concave surface, negative optical power), and a fifth lens 5 (double convex surface, positive optical power) by gluing. The third lens 3 converges light, the fourth lens 4 diverges and corrects chromatic aberration, and the fifth lens 5 converges again. The gluing interfaces of the three lenses reduce chromatic aberration and spherical aberration.

[0089] In some implementation manners, the material of the eighth lens 8 is a plastic material.

[0090] The eighth lens 8 uses a plastic material. Its concave - plane structure is adapted to the injection molding process, reducing the manufacturing cost. The negative optical power design balances the positive optical power of the front section. The thermal expansion coefficient of the plastic material is controlled by the structural compensation design to avoid deformation at high temperatures.

[0091] In some implementation manners, the distance from the surface where the light valve 10 is located to the vertex of the object side of the first lens 1 is denoted as BFL, and the distance from the vertex of the object side of the first lens 1 to the vertex of the image side of the ninth lens 9 is denoted as L1, where 0.05 < BFL / L1 < 0.63.

[0092] The ratio of the distance (BFL) from the light valve 10 to the object-side vertex of the first lens 1 to the distance (L1) from the first lens 1 to the image-side vertex of the ninth lens 9 is defined as 0.05 - 0.63. This ratio ensures the matching between the light valve 10 and the main lens group. If the ratio is too small, the light valve 10 will be blocked; if it is too large, redundant space will be increased.

[0093] Reference Figure 1a 、 Figure 2a and Figure 3a , in some implementations, it further includes an illumination prism 30 and an image offset mirror 40 arranged in sequence from the object side to the image side between the light valve 10 and the first lens 1. Denote the distance from the plane on the object side of the illumination prism 30 to the image-side vertex of the ninth lens 9 as L2, and denote the total focal length of the zoom lens as F, where 0.007 < F / L2 < 0.8.

[0094] The illumination prism 30 and the image offset mirror 40 are located between the light valve 10 and the first lens 1. The illumination prism 30 homogenizes the light, and the image offset mirror 40 corrects the optical axis offset. The ratio of the total length (L2) from the object side of the illumination prism 30 to the image side of the ninth lens 9 to the total focal length (F) is defined as 0.007 - 0.8, which balances the compactness and the light path convergence efficiency.

[0095] In some implementations, the projection ratio of the zoom lens is greater than or equal to 0.8 and less than or equal to 1.5.

[0096] The projection ratio range of the zoom lens is 0.8 - 1.5, which is achieved by switching the relay lens group. A low projection ratio (0.8) is suitable for narrow spaces, and a high projection ratio (1.5) meets the requirements of large-screen displays. The range setting takes into account both practicality and the optical performance limit.

[0097] Figure 3a The following shows a schematic structural diagram of a zoom lens provided by another embodiment of the present invention. Taking Figure 3a the shown zoom lens as an example (without a configured relay lens group), the projection ratio of the entire zoom lens is 1.15, the focal length is 9.8 mm, the resolution is 118 lp / mm, the projected image size is 20 to 190 inches, and the main projected size is 50 to 150 inches. Figures 3b to 3f For Figure 3a the shown zoom lens, it is an image quality evaluation diagram.

[0098] Specifically, from Figure 3b the light ray fan diagram, it can be seen that the distribution of light rays in the basic main lens group shows symmetry and consistency, indicating that the optical path design of the main lens group itself is reasonable, and preliminary aberration correction can be achieved without relying on the relay lens group.

[0099] From Figure 3cIt can be seen from the SPOT diagram that the spot is close to the diffraction limit in the central field of view, and the shape is regular with a slight increase in the edge field of view, indicating that the main mirror group already has the basic image quality guarantee ability when used independently.

[0100] From Figure 3d It can be seen from the MTF diagram that the contrast at 118 lp / mm is close to the theoretical limit, proving that the power distribution and lens combination design of the main mirror group effectively improve the resolution and provide support for the core performance.

[0101] From Figure 3e It can be seen from the RI diagram that the edge illuminance loss is about 10%, which is better than the state after matching with the relay mirror group, indicating that the vignetting effect is smaller when the main mirror group is used alone, providing a high-quality optical basis for subsequent modular expansion.

[0102] From Figure 3f It can be seen from the MTF vs field of view diagram that the MTF value fluctuation in the full field of view is small, verifying the image quality balance of the main mirror group design in the independent state and providing a reliable platform for the adaptation of the relay mirror group.

[0103] Figures 3b to 3f It shows that the main mirror group, as the core module, has high resolution and image quality stability by itself, laying a technical foundation for the flexible expansion of the relay mirror group (realizing a projection ratio of 0.8 - 1.5).

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention.

Claims

1. A small-volume zoom lens, characterized in that: It includes a main mirror group and a relay mirror group, the total length of the main mirror group is less than or equal to 110 mm; the main mirror group along the optical axis from the object side to the image side is: Light valve; A first lens having a convex surface on the object side and a concave surface on the image side, wherein the first lens has positive optical power and is made of glass; A second lens having convex spherical surfaces on both the object side and the image side, and the optical power of the second lens is positive; A triplet lens having a biconvex-biconcave-biconvex structure, wherein the optical power of the triplet lens is positive, negative, and positive in sequence; a sixth lens having a convex surface on the object side and a concave surface on the image side, wherein the optical power of the sixth lens is negative; Aperture; a seventh lens having convex spherical surfaces on both the object side and the image side, and having positive refractive power; an eighth lens having a concave object side and a flat image side, wherein the eighth lens has a negative optical power; a ninth lens having a concave surface on the object side and a convex surface on the image side, wherein the ninth lens has positive optical power and is made of glass; The relay lens group is located on a side of the aperture close to the seventh lens, and includes at least two lenses.

2. The zoom lens according to claim 1, wherein: The relay lens group includes a first relay lens group, which is located between the seventh lens and the eighth lens, and includes a first relay lens, a second relay lens, a third relay lens and a fourth relay lens arranged in sequence from the object side to the image side, the object side of the first relay lens is a concave surface and the image side is a flat surface, the object side of the second relay lens is a concave surface and the image side is a convex surface, the object side of the third relay lens is a concave surface and the image side is a convex surface, and the object side of the fourth relay lens is a convex surface and the image side is also a convex surface.

3. The zoom lens according to claim 2, wherein: The focal length of the zoom lens is greater than or equal to 7.5 mm and less than or equal to 7.9 mm, and the resolution is greater than or equal to 116 lp / mm and less than or equal to 120 lp / mm.

4. The zoom lens according to claim 1, wherein: The relay lens group includes a second relay lens group, which is located on the side of the ninth lens away from the aperture, and includes a fifth relay lens and a sixth relay lens arranged in sequence from the object side to the image side, the object side of the fifth relay lens is a concave surface and the image side is a convex surface, and the object side of the sixth relay lens is a concave surface and the image side is a convex surface.

5. The zoom lens according to claim 4, wherein: The focal length of the zoom lens is greater than or equal to 12.2 mm and less than or equal to 12.6 mm, and the resolution is greater than or equal to 116 lp / mm and less than or equal to 120 lp / mm.

6. The zoom lens according to claim 1, wherein: The triplet lens includes a third lens, a fourth lens and a fifth lens arranged in sequence from the object side to the image side, the object side and the image side of the third lens are both convex, the object side and the image side of the fourth lens are both concave, and the object side and the image side of the fifth lens are both convex.

7. The zoom lens according to claim 1, wherein: The eighth lens is made of plastic.

8. The zoom lens according to claim 1, wherein: The distance from the surface where the light valve is located to the object side vertex of the first lens is recorded as BFL, and the distance from the object side vertex of the first lens to the image side vertex of the ninth lens is recorded as L1, where 0.05 <BFL / L1<0.63。 9. The zoom lens according to claim 1, wherein: It also includes an illumination prism and an image biasing mirror located between the light valve and the first lens and arranged in sequence from the object side to the image side. The distance from the object side of the illumination prism to the image side vertex of the ninth lens is denoted as L2, and the total focal length of the zoom lens is denoted as F, wherein 0.007<F / L2<0.

8.

10. The zoom lens according to claim 1, wherein: The throw ratio of the zoom lens is greater than or equal to 0.8 and less than or equal to 1.5.

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