Small-size zoom lens

Abstract

The invention provides a small-size zoom lens, and relates to the technical field of projection zoom lenses. The zoom lens comprises a main lens group and a relay lens group. The total length of the main lens group is less than or equal to 110 mm. The primary lens group sequentially comprises a light valve, a first lens group and a second lens group from the object side to the image side along the optical axis. The object side of the first lens is a convex surface, and the image side is a concave surface; the object side and the image side of the second lens are convex surfaces and are spherical surfaces; the triplet lens is provided with a biconvex surface-biconcave surface-biconvex surface structure; the object side of the sixth lens is a convex surface, and the image side of the sixth lens is a concave surface; a diaphragm; the object side and the image side of the seventh lens are convex surfaces and are spherical surfaces; the object side of the eighth lens is a concave surface, and the image side of the eighth lens is a plane; the object side of the ninth lens is a concave surface, and the image side is a convex surface; the relay lens group is located on the side, close to the seventh lens, of the diaphragm. Through the compact design of the main lens group and the modular configuration of the relay lens group, the problems of large size, high cost and insufficient image quality and service life of a traditional zoom lens are systematically solved.

Description

Technical Field

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

[0002] In recent years, with the widespread application of projection equipment in home entertainment, business meetings and education, users have increasingly higher requirements for the performance of projection systems, especially in terms of small size, high image quality, variable focus, etc. However, the existing projection lens design faces significant technical bottlenecks in achieving the above requirements, which are manifested in the following problems: the cumbersome operation of fixed-focus projection systems, the cost and volume issues of zoom projection systems, and insufficient life and durability.

[0003] Based on the above technical problems, there is an urgent need for a zoom lens solution that has small size, high image quality, long life and controllable cost. Summary of the invention

[0004] In view of the above problems existing in the prior art, the present invention provides a small-volume zoom lens, comprising a main lens group and a relay lens group, wherein the total length of the main lens group is less than or equal to 110 mm; the main lens group is sequentially as follows from the object side to the image side along the optical axis: Light valve; A first lens having a convex surface on the object side and a concave surface on the image side, 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 having positive refractive power; 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, and 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, and the optical power of the eighth lens is negative; a ninth lens having a concave object side surface and a convex image side surface, the ninth lens having positive optical power and made of glass; The relay lens group is located on the side of the aperture close to the seventh lens, and includes at least two lenses.

[0005] In some implementations, 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 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, and the object side of the fourth relay lens is convex and the image side is also convex.

[0006] 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.

[0007] In some implementations, 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 concave and the image side is convex, and the object side of the sixth relay lens is concave and the image side is convex.

[0008] 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.

[0009] 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, and the object side and the image side of the fifth lens are both convex.

[0010] In some implementations, the eighth lens is made of plastic.

[0011] In some implementations, the distance from the light valve surface 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。

[0012] In some implementations, an illumination prism and an image biasing mirror are further included, which are located between the light valve and the first lens and are arranged in sequence from the object side to the image side. The distance from the object side surface 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.

[0013] In some implementations, the throw ratio of the zoom lens is greater than or equal to 0.8 and less than or equal to 1.5.

[0014] Compared with the prior art, the beneficial effects of the present invention are: through the compact design of the main lens group and the modular configuration of the relay lens group, the problems of large size, high cost, insufficient image quality and life of the traditional zoom lens are systematically solved. The total length of the main lens group is ≤110 mm, and the aberration is balanced by the alternating positive and negative focal length distribution (such as positive, positive, positive, negative, positive, negative, positive, negative, positive), and the three-cemented lens integrates the chromatic aberration correction function to reduce the number of lenses; the aperture 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 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. Key lens design enhances performance: The first lens (convex-concave) and the ninth lens (concave-convex) are made of glass to improve high temperature resistance and wear resistance, and extend life; the sixth lens (negative focal length) corrects spherical aberration, the eighth lens (concave-flat) simplifies the process and suppresses image curvature, and the seventh lens (double convex spherical surface) optimizes light convergence. The above structures work together to achieve a high resolution of 118lp / mm while reducing the size of the lens, adapting to the change of 50-150-inch screens, taking into account low cost, high image quality and long life, breaking through the technical bottleneck of traditional solutions. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1a FIG. 1 is a schematic structural diagram of a zoom lens provided by an embodiment of the present invention.

[0017] Figure 1b for Figure 1a Ray fan diagram of the zoom lens shown.

[0018] Figure 1c for Figure 1a SPOT diagram of the zoom lens shown.

[0019] Figure 1d for Figure 1a MTF graph of the zoom lens shown.

[0020] Figure 1e for Figure 1a RI graph for the zoom lens shown.

[0021] Figure 1f for Figure 1a MTF vs Field of View plot for the zoom lens shown.

[0022] Figure 2a FIG. 4 is a schematic structural diagram of a zoom lens provided by another embodiment of the present invention.

[0023] Figure 2b for Figure 2a Ray fan diagram of the zoom lens shown.

[0024] Figure 2c for Figure 2a SPOT diagram of the zoom lens shown.

[0025] Figure 2d for Figure 2a MTF graph of the zoom lens shown.

[0026] Figure 2e for Figure 2a RI graph for the zoom lens shown.

[0027] Figure 2f for Figure 2a MTF vs Field of View plot for the zoom lens shown.

[0028] Figure 3a FIG. 4 is a schematic structural diagram of a zoom lens provided by another embodiment of the present invention.

[0029] Figure 3b for Figure 3a Ray fan diagram of the zoom lens shown.

[0030] Figure 3c for Figure 3a SPOT diagram of the zoom lens shown.

[0031] Figure 3d for Figure 3a MTF graph of the zoom lens shown.

[0032] Figure 3e for Figure 3a RI graph for the zoom lens shown.

[0033] Figure 3f for Figure 3a MTF vs Field of View plot for the zoom lens shown.

[0034] Figure numerals: light valve 10; aperture 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 biasing mirror 40. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the scope of protection of the present invention.

[0036] The specific implementation modes of the present invention are described below.

[0037] Figure 1a FIG. 1 is a schematic diagram of the structure of a zoom lens provided by an embodiment of the present invention. Figure 1a As shown, the present invention proposes a small-volume zoom lens, comprising a main lens group and a relay lens group, wherein the total length of the main lens group is less than or equal to 110 mm; the main lens group is sequentially as follows from the object side to the image side along the optical axis: Light valve 10; A first lens 1 having a convex surface on the object side and a concave surface on the image side, wherein the first lens 1 has positive optical power and is made of glass; A second lens 2 having convex and spherical surfaces on both the object side and the image side, and the optical power of the second lens 2 is positive; A triplet lens 345 having a biconvex-biconcave-biconvex structure, wherein the optical power of the triplet lens 345 is positive, negative, and positive in sequence; a sixth lens 6 having a convex surface on the object side and a concave surface on the image side, and the optical power of the sixth lens 6 is negative; Aperture 50; a seventh lens element 7 having convex spherical surfaces on both the object side and the image side, and having positive refractive power; an eighth lens 8 having a concave object side and a flat image side, and the eighth lens 8 has a negative refractive power; a ninth lens 9 having a concave surface on the object side and a convex surface on the image side, the ninth lens 9 has positive refractive power and is made of glass; The relay lens group is located on the side of the aperture 50 close to the seventh lens 7 and includes at least two lenses.

[0038] The present embodiment relates to a small-volume zoom lens, the core of which is to achieve the comprehensive goals of volume compression, zoom flexibility and high image quality through the coordinated design of the main lens group and the relay lens group. The total length of the main lens group is strictly limited to no more than 110 mm, and it includes a light valve 10, a first lens 1 to a ninth lens 9 from the object side to the image side, and the focal length of each lens is distributed as positive, positive, positive, negative, positive, negative, positive, negative, positive. The light valve 10 serves as the input end of the light source to control the light entering the main lens group; the first lens 1 is a convex-concave structure made of glass with a positive focal length. Its convex object side design can quickly converge light, and the concave image side is used for preliminary correction of spherical aberration. The second lens 2 is a double convex spherical lens with a positive focal length, which further converges light and balances field curvature. The triplet lens 345 is composed of the third to fifth lenses 5, and the optical power is positive, negative, and positive in sequence. Its biconvex-biconcave-biconvex structure is integrated through a bonding process, which effectively corrects chromatic aberration and reduces the number of lenses, avoiding the volume expansion caused by the gap between discrete lenses in the traditional design. The sixth lens 6 is a convex-concave structure with a negative optical power, which is used to offset the accumulated aberration of the positive optical power of the front section and shorten the back focal length. The aperture 50 is fixed to the rear side of the sixth lens 6 to control the beam aperture to stabilize the optical path. The seventh lens 7 is a biconvex spherical lens with a positive optical power. It is designed close to the aperture 50 to converge light and correct astigmatism. The eighth lens 8 is a concave-plane structure with a negative optical power. The plane image side simplifies the processing technology. The negative optical power balances the overshoot of the positive optical power of the front section and suppresses the curvature of the image plane. The ninth lens 9 is a concave-convex structure with a positive optical power. The glass material ensures the wear resistance of the screen end. Its convex image side optimizes the incident angle of the edge light and reduces distortion. The relay lens group is located at the rear side of the aperture 50 (close to the seventh lens 7), and includes at least two lenses. The projection ratio can be adjusted by replacing different relay lens groups without the need for a complex mechanical moving structure.

[0039] The total length limit of the main lens group is combined with the alternating distribution of optical power, which significantly compresses the longitudinal space; the triplet lens 345 integrates the chromatic aberration correction function to reduce the number of lenses; the fixed design of the aperture 50 avoids horizontal space occupation; the modular configuration of the relay lens group reduces the complexity of zooming. The lenses at both ends (the first lens 1 and the ninth lens 9) are made of glass material to improve high temperature resistance and wear resistance and extend service life. The negative optical power design of the sixth lens 6 and the eighth lens 8 synergistically suppresses spherical aberration and image curvature to ensure the consistency of resolution from center to edge.

[0040] 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 total optical 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.

[0041] refer to Figure 1aIn some implementations, the relay lens group includes a first relay lens group, which is 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 a concave surface and the image side is a flat surface, the object side of the second relay lens 202 is a concave surface and the image side is a convex surface, the object side of the third relay lens 203 is a concave surface and the image side is a convex surface, and the object side of the fourth relay lens 204 is a convex surface and the image side is also a convex surface.

[0042] This embodiment refines 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 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 is a concave-plane structure with a negative focal length. The plane image side simplifies processing and initially diverges the light; the second relay lens 202 is a concave-convex structure with a positive focal length, which is used to converge the light and correct astigmatism; the third relay lens 203 is a concave-convex structure with a positive focal length, which further optimizes the convergence of the light path; the fourth relay lens 204 is a biconvex structure with a positive focal length, which finally outputs the light and balances the field curvature. The focal lengths of the four lenses are distributed in order of negative, positive, positive, and positive. The positive focal length accumulation of the rear section of the main lens group is offset by the front placement of a negative focal length lens to avoid aberration amplification.

[0043] The first relay lens group achieves a low projection ratio (such as 0.8) through a four-lens combination. The concave-flat lens reduces the difficulty of processing, and the biconvex terminal lens ensures that the light enters the screen smoothly and reduces edge distortion. The four-lens focal distribution cooperates with the main lens group to maintain high resolution (116-120lp / mm).

[0044] The second relay lens 202 can be replaced with a biconcave structure with a negative optical power. In this case, the optical power of the subsequent lenses needs to be adjusted to a higher positive value to maintain the total optical power balance.

[0045] 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.

[0046] The focal length range of the main lens group and the first relay lens group is limited to 7.5-7.9 mm, and the resolution is 116-120lp / mm. This range is achieved through the precise design of the lens curvature radius and spacing: too small a focal length may cause excessive convergence of light and induce spherical aberration, while too large a focal length may reduce zoom sensitivity; the lower limit of the resolution ensures clear image details, and the upper limit avoids over-correction, which increases the complexity of the process.

[0047] The 7.5-7.9mm focal length balances the zoom range and aberration control requirements; the 116-120lp / mm resolution covers the mainstream projection resolution standards while being compatible with manufacturing tolerances.

[0048] by Figure 1a Taking 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 118lp / mm, the projection screen size is 20 to 190 inches, and the main projection size is 70 to 160 inches. Figure 1b to Figure 1f for Figure 1a Image quality evaluation chart of the zoom lens shown.

[0049] Specifically, Figure 1b The ray fan diagram shows the light path distribution of light through the lens at different field angles, verifying the symmetry of the optical axis and the effect of astigmatism correction. Figure 1b The concentration of the light ray trajectories in the middle indicates the system's ability to suppress astigmatism, and there is no obvious divergence of the light rays at the edge of the field of view, indicating that the field curvature is well controlled.

[0050] Figure 1c The SPOT diagram shows the shape and size of the light spot at different positions in the field of view. The light spot is close to a circle with uniform diameter, proving that the spherical aberration and coma are fully corrected, and there is no obvious deformation or tailing in the edge field of view.

[0051] Figure 1d The MTF graph (Modulation Transfer Function) reflects the lens's ability to respond to different spatial frequencies. The curve still maintains a high contrast at 118lp / mm, indicating that the resolution meets the design requirements, and the MTF value from the center to the edge decreases slightly, indicating excellent image quality uniformity.

[0052] Figure 1e The RI graph (Relative Illumination) shows the brightness decay from the center to the edge of the image. The curve drops gently, and the edge illumination loss is less than 15%, indicating that the lens effectively controls the vignetting effect and is suitable for large-format projection.

[0053] Figure 1f The MTF vs FOV diagram summarizes the MTF value change trends for different FOVs, showing high resolution consistency across the entire FOV without any local resolution drop, verifying image quality stability during zooming.

[0054] Depend on Figure 1b to Figure 1f It can be seen that at a low throw ratio (0.8), the zoom lens maintains high resolution (118lp / mm) and uniform image quality in the range of 70-160 inches, meeting the needs of large-screen projection in a small space.

[0055] Figure 2a FIG. 2 is a schematic diagram of the structure of a zoom lens provided by another embodiment of the present invention. Figure 2aAs shown, in some implementations, the relay lens group includes a second relay lens group, which 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, and the object side of the sixth relay lens 206 is concave and the image side is convex.

[0056] The second relay lens group is located on the side of the ninth lens 9 away from the aperture 50, and is composed of a fifth relay lens 205 and a sixth relay lens 206. The fifth relay lens 205 is a concave-convex structure with a negative focal length, which initially diverges the light; the sixth relay lens 206 is a concave-convex structure with a positive focal length, which converges the light and corrects the distortion. The focal lengths of the two lenses are distributed as negative and positive, which are adapted to the requirements of high throw ratios (such as 1.5).

[0057] The negative-positive power distribution expands the throw ratio range, the concave-convex structure suppresses astigmatism, and the two-lens configuration simplifies the volume of the relay lens group.

[0058] 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.

[0059] The focal length of the main lens group and the second relay lens group is limited to 12.2-12.6 mm, and the resolution is 116-120lp / mm. This range ensures the stability of the optical path under high projection ratio. A focal length that is too small will easily cause the edge light to escape, and a focal length that is too large will increase the total length of the lens.

[0060] by Figure 2a Taking 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 118lp / mm, the projection screen size is 40 to 120 inches, and the main projection size is 50 to 150 inches. Figure 2b to Figure 2f for Figure 2a Image quality evaluation chart of the zoom lens shown.

[0061] Specifically, by Figure 2b From the ray fan diagram, we can see that the ray trajectory remains compactly distributed at a high throw ratio, indicating that the optical path is stable at a long focal length and that there is no deterioration in astigmatism or field curvature due to the increase in focal length.

[0062] Depend on Figure 2c From the SPOT diagram, we can see that the diameter of the light spot at the telephoto end is slightly larger than that at the short focal end, but the shape is still close to a circle, and there is no obvious coma or distortion at the edge of the field of view, indicating that the aberration correction scheme is adapted to different focal length requirements.

[0063] Depend on Figure 2dFrom the MTF graph, we can see that the contrast at 118lp / mm is slightly lower than that at the low throw ratio state, but is still significantly higher than the industry standard (93lp / mm), proving that the image quality does not drop significantly in telephoto mode and meets the requirements of high-resolution projection.

[0064] Depend on Figure 2e From the RI graph, we can see that the edge illumination loss is about 20%, which is within an acceptable range, indicating that the lens can still maintain picture brightness uniformity at a high throw ratio.

[0065] Depend on Figure 2f From the MTF vs field of view diagram, we can see that the MTF value of the center field of view is higher, and the edge field of view decreases slightly, but the overall trend is smooth, indicating that the image quality transition in telephoto mode is natural without sudden defects.

[0066] Figure 2b to Figure 2f The applicability of zoom lenses under high throw ratio (1.5) has been verified. Especially in the range of 50-150 inches, the resolution and image quality stability are still better than traditional zoom lenses, making it suitable for long-distance projection scenes.

[0067] refer to Figure 1a , Figure 2a and Figure 3a In some implementations, 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, the object side and the image side of the third lens 3 are both convex, the object side and the image side of the fourth lens 4 are both concave, and the object side and the image side of the fifth lens 5 are both convex.

[0068] The triplet lens 345 is composed of a third lens 3 (biconvex surface, positive power), a fourth lens 4 (biconcave surface, negative power) and a fifth lens 5 (biconvex surface, positive power). The third lens 3 converges light, the fourth lens 4 diverges and corrects chromatic aberration, and the fifth lens 5 converges again. The cemented interface of the three reduces chromatic aberration and spherical aberration.

[0069] In some implementations, the eighth lens 8 is made of plastic.

[0070] The eighth lens 8 is made of plastic material, and its concave-flat structure is adapted to the injection molding process to reduce manufacturing costs. 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 high temperature deformation.

[0071] In some implementations, the distance from the surface of the light valve 10 to the object side vertex of the first lens 1 is recorded as BFL, and the distance from the object side vertex of the first lens 1 to the image side vertex of the ninth lens 9 is recorded as L1, where 0.05 <BFL / L1<0.63。

[0072] 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 limited to 0.05-0.63. This ratio ensures the matching of the light valve 10 and the main mirror group. If the ratio is too small, the light valve 10 will be blocked, and if it is too large, redundant space will be increased.

[0073] refer to Figure 1a , Figure 2a and Figure 3a In some implementations, it also includes an illumination prism 30 and an image biasing mirror 40 located between the light valve 10 and the first lens 1 and arranged in sequence from the object side to the image side. The distance from the object side surface of the illumination prism 30 to the image side vertex of the ninth lens 9 is denoted as L2, and the total focal length of the zoom lens is denoted as F, wherein 0.007<F / L2<0.8.

[0074] The illumination prism 30 and the image biasing mirror 40 are located between the light valve 10 and the first lens 1. The illumination prism 30 homogenizes the light, and the image biasing mirror 40 corrects the optical axis deviation. 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 limited to 0.007-0.8, which balances the compactness and the light path convergence efficiency.

[0075] In some implementations, the throw ratio of the zoom lens is greater than or equal to 0.8 and less than or equal to 1.5.

[0076] The zoom lens has a throw ratio range of 0.8-1.5, which is achieved by switching the relay lens group. The low throw ratio (0.8) is suitable for small spaces, and the high throw ratio (1.5) meets the needs of large screens. The range setting takes into account both practicality and the limits of optical performance.

[0077] Figure 3a FIG. 1 is a schematic diagram of the structure of a zoom lens provided by another embodiment of the present invention. Figure 3a Taking the zoom lens shown as an example (without relay lens), the projection ratio of the entire zoom lens is 1.15, the focal length is 9.8 mm, the resolution is 118lp / mm, the projection screen size is 20 to 190 inches, and the main projection size is 50 to 150 inches. Figure 3b to Figure 3f for Figure 3a Image quality evaluation chart of the zoom lens shown.

[0078] Specifically, by Figure 3b From the light fan diagram, we can see that the distribution of light in the basic primary mirror group is symmetrical and consistent, indicating that the optical path design of the primary mirror group itself is reasonable and preliminary aberration correction can be achieved without relying on the relay mirror group.

[0079] Depend on Figure 3cFrom the SPOT diagram, we can see that the light spot is close to the diffraction limit in the central field of view, and the edge field of view is slightly enlarged but the shape is regular, indicating that the main mirror group has the basic image quality guarantee capability when used independently.

[0080] Depend on Figure 3d From the MTF graph, we can see that the contrast at 118lp / mm is close to the theoretical limit, proving that the optical power distribution of the main mirror group and the lens combination design effectively improve the resolution and provide support for the core performance.

[0081] Depend on Figure 3e From the RI diagram, we can see that the edge illumination loss is about 10%, which is better than the state after matching the relay mirror group. This shows that the vignetting effect is smaller when the main mirror group is used alone, providing a high-quality optical foundation for subsequent modular expansion.

[0082] Depend on Figure 3f From the MTF vs field of view diagram, we can see that the MTF value of the entire field of view fluctuates slightly, which verifies the image quality balance of the main mirror group design in an independent state and provides a reliable platform for the adaptation of the relay mirror group.

[0083] Figure 3b to Figure 3f This shows that the main mirror group, as a core module, has high resolution and image quality stability, laying a technical foundation for the flexible expansion of the relay mirror group (to achieve a projection ratio of 0.8-1.5).

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions 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.

Images