Zoom projection optical system with variable aperture

Abstract

The invention discloses a zoom projection optical system with a variable aperture, which sequentially comprises a focusing group, a zoom group and a fixed group from an object space to an image space, the focusing group comprises at least one movable lens group, and the zoom group comprises the variable aperture and at least four movable lens groups; wherein the focusing group is used for obtaining a clear picture under the condition of different projection distances by moving at least one lens group; the zoom group is used for obtaining pictures with different sizes by moving at least four lens groups under the condition that the projection distance is not changed; and the fixed group is used for assembling the zoom projection optical system. The embodiment of the invention can realize continuous zooming and improve the imaging quality, and can be widely applied to the technical field of optical devices.

Description

Technical Field

[0001] The present invention relates to the technical field of optical devices, and in particular to a variable-aperture zoom projection optical system. Background Art

[0002] Traditional consumer projectors mainly use fixed-focus projection lenses. To obtain different screen sizes, only the projection distance can be changed, making it difficult to meet the increasing usage requirements. In addition, most traditional projection lenses have a fixed aperture and cannot optimize the imaging quality of the projection image by adjusting the aperture diameter. Summary of the Invention

[0003] In view of this, the purpose of the embodiments of the present invention is to provide a variable-aperture zoom projection optical system that can achieve continuous zooming and improve imaging quality.

[0004] The embodiments of the present invention provide a variable-aperture zoom projection optical system, which sequentially includes a focusing group, a zooming group, and a fixed group from the object side to the image side. The focusing group includes at least one movable lens group, and the zooming group includes a variable aperture and at least four movable lens groups; wherein,

[0005] The focusing group is used to obtain a clear image by moving at least one lens group under different projection distances;

[0006] The zooming group is used to obtain images of different sizes by moving at least four lens groups without changing the projection distance;

[0007] The fixed group is used for the assembly of the zoom projection optical system.

[0008] Optionally, the focal length of the zooming group can be changed by moving at least four lens groups in the zooming group, and the minimum focal length and the maximum focal length of the zooming group satisfy the following relationship:

[0009] 1.2 < f t / f w < 1.5

[0010] wherein, f t represents the maximum focal length of the zooming group, and f w represents the minimum focal length of the zooming group.

[0011] Optionally, the focusing group includes at least one aspherical lens. The focal length of the zooming group can be changed by moving at least four lens groups in the zooming group, and the focal length of the aspherical lens and the minimum focal length of the zooming group satisfy the following relationship:

[0012] -0.1 < f w / fa <-0.05

[0013] Among them, f a represents the focal length of the aspherical lens, and f w represents the minimum focal length of the zoom group.

[0014] Optionally, the focusing group includes at least one aspherical lens, the focusing group has a negative optical power, and the focal length of the aspherical lens and the focal length of the focusing group satisfy the following relationship:

[0015] -0.08 < f1 / f a <-0.04

[0016] Among them, f a represents the focal length of the aspherical lens, and f1 represents the focal length of the focusing group.

[0017] Optionally, by moving at least four lens groups in the zoom group, the focal length of the zoom group can be changed, and the minimum focal length of the zoom group and the total length of the zoom projection optical system satisfy the following relationship:

[0018] 0.06 < f w / L < 0.1

[0019] Among them, f w represents the minimum focal length of the zoom group, and L represents the total length of the zoom projection optical system.

[0020] Optionally, by moving at least four lens groups in the zoom group, the focal length of the zoom group can be changed, and the minimum focal length of the zoom group and the maximum optical aperture of the zoom projection optical system satisfy the following relationship:

[0021] 0.15 < f w / D < 0.35

[0022] Among them, f w represents the minimum focal length of the zoom group, and D represents the maximum optical aperture of the zoom projection optical system.

[0023] Optionally, by moving at least four lens groups in the zoom group, the maximum object field angle obtained is equal to or greater than 80 degrees.

[0024] Optionally, the back focal length of the zoom projection optical system and the total length of the zoom projection optical system satisfy the following relationship:

[0025] 0.15 < FBL / L < 0.25

[0026] Among them, FBL represents the back focal length of the zoom projection optical system, and L represents the total length of the zoom projection optical system.

[0027] Optionally, the focusing lens group includes a first lens group, and the first lens group includes a first lens, a second lens, and a third lens; the zoom lens group includes a second lens group to a fifth lens group, the second lens group includes a fourth lens and a fifth lens, the third lens group includes a sixth lens, the fourth lens group includes a seventh lens and an eighth lens, and the fifth lens group includes a ninth lens to a twelfth lens; the fixed lens group includes a sixth lens group, and the sixth lens group includes a thirteenth lens.

[0028] Optionally, the first lens includes a meniscus negative lens, the second lens includes a meniscus negative lens, the third lens includes a biconcave negative lens, the fourth lens includes a biconvex positive lens, the fifth lens includes a meniscus negative lens, the fourth lens and the fifth lens form a cemented lens, the sixth lens includes a biconvex positive lens, the seventh lens includes a biconvex positive lens, the eighth lens includes a biconcave negative lens, the seventh lens and the eighth lens form a cemented lens, the ninth lens includes a biconcave negative lens, the tenth lens includes a biconvex positive lens, the eleventh lens includes a meniscus negative lens, the ninth lens, the tenth lens, and the eleventh lens form a triple cemented lens, the twelfth lens includes a meniscus positive lens, and the thirteenth lens includes a biconvex positive lens.

[0029] Implementing the embodiments of the present invention has the following beneficial effects: The embodiments of the present invention include a focusing lens group, a zoom lens group, and a fixed lens group in sequence from the object side to the image side. By moving at least one lens group in the focusing lens group, a clear image can be obtained under different projection distances. By moving at least four lens groups in the zoom lens group, images of different sizes can be obtained without changing the projection distance; in addition, the variable aperture is located in one of the moving lens groups in the zoom lens group. By automatically and precisely controlling the aperture diameter, the contrast and clarity of the projected image can be improved; thus, while realizing continuous zoom, the imaging of the imaging image is also improved by the variable aperture, and 4K resolution can be supported. Description of the Drawings

[0030] Figure 1 is a structural block diagram of a zoom projection optical system with a variable aperture provided by an embodiment of the present invention;

[0031] Figure 2 is a structural block diagram of the zoom projection optical system with a variable aperture in Embodiment 1 provided by an embodiment of the present invention;

[0032] Figure 3 is an MTF schematic diagram when the focal length of the zoom lens group in Embodiment 1 provided by an embodiment of the present invention is 9.5 mm;

[0033] Figure 4 It is a schematic MTF diagram when the focal length of the zoom group in Embodiment 1 provided by the embodiment of the present invention is 12.7 mm;

[0034] Figure 5 It is a structural block diagram of a variable-aperture zoom projection optical system in Embodiment 2 provided by the embodiment of the present invention;

[0035] Figure 6 It is a schematic MTF diagram when the focal length of the zoom group in Embodiment 2 provided by the embodiment of the present invention is 9.4 mm;

[0036] Figure 7 It is a schematic MTF diagram when the focal length of the zoom group in Embodiment 2 provided by the embodiment of the present invention is 12.6 mm;

[0037] Figure 8 It is a structural block diagram of a variable-aperture zoom projection optical system in Embodiment 3 provided by the embodiment of the present invention;

[0038] Figure 9 It is a schematic MTF diagram when the focal length of the zoom group in Embodiment 3 provided by the embodiment of the present invention is 9.4 mm;

[0039] Figure 10 It is a schematic MTF diagram when the focal length of the zoom group in Embodiment 3 provided by the embodiment of the present invention is 12.6 mm;

[0040] Figure 11 It is a structural block diagram of a variable-aperture zoom projection optical system in Embodiment 4 provided by the embodiment of the present invention;

[0041] Figure 12 It is a schematic MTF diagram when the focal length of the zoom group in Embodiment 4 provided by the embodiment of the present invention is 9.4 mm;

[0042] Figure 13 It is a schematic MTF diagram when the focal length of the zoom group in Embodiment 4 provided by the embodiment of the present invention is 12.6 mm. Detailed implementation manners

[0043] The following further elaborates on the present invention in detail in conjunction with the accompanying drawings and specific embodiments. For the step numbers in the following embodiments, they are only set for the convenience of elaboration and explanation, and no limitation is imposed on the order between steps. The execution order of each step in the embodiments can be adaptively adjusted according to the understanding of those skilled in the art.

[0044] It should be noted that although the functional modules are divided in the device schematic diagram and the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different module division from that in the device or a different order from that in the flowchart. The terms "first", "second", etc. in the specification, claims and the above-mentioned drawings are used to distinguish similar objects and do not necessarily need to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0045] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs. The terms used herein are only for the purpose of describing the embodiments of this application and are not intended to limit this application.

[0046] As Figure 1 shown, an embodiment of the present invention provides a variable-aperture zoom projection optical system, which sequentially includes a focusing group, a zooming group and a fixed group from the object side to the image side. The focusing group includes at least one movable lens group, and the zooming group includes a variable aperture and at least four movable lens groups; wherein,

[0047] The focusing group is used to obtain a clear picture by moving at least one lens group under different projection distances;

[0048] The zooming group is used to obtain pictures of different sizes by moving at least four lens groups without changing the projection distance;

[0049] The fixed group is used for the assembly of the zoom projection optical system.

[0050] It should be noted that the variable aperture is located in one of the movable lens groups in the zooming group, and the aperture diameter can be automatically and precisely controlled by a motor. The number and structure of the lenses in the focusing group, the zooming group or the fixed group are determined according to actual applications, and are not specifically limited in this embodiment.

[0051] The variable-aperture zoom projection optical system may further include a prism and a projection surface, etc.

[0052] Optionally, by moving at least four lens groups in the zooming group, the focal length of the zooming group can be changed, and the minimum focal length and the maximum focal length of the zooming group satisfy the following relationship:

[0053] 1.2 < f t / f w <1.5

[0054] where f t represents the maximum focal length of the zoom group, and f w represents the minimum focal length of the zoom group.

[0055] The focal length of the zoom group is changed by moving one or more lens groups of the zoom group. The actual focal length of the zoom group is determined according to the actual application and is not specifically limited in this embodiment.

[0056] Optionally, the focusing group includes at least one aspherical lens. The focal length of the zoom group can be changed by moving at least four lens groups in the zoom group. The focal length of the aspherical lens and the minimum focal length of the zoom group satisfy the following relationship:

[0057] -0.1 < f w / f a <-0.05

[0058] where f a represents the focal length of the aspherical lens, and f w represents the minimum focal length of the zoom group.

[0059] An aspherical lens refers to a lens with at least one optical surface that is not spherical (or planar). By compensating for aberrations through aspherical design, the imaging quality can be improved and the number of lenses required for the system can be reduced.

[0060] It should be noted that the Abbe number of the focusing group is between 40 and 60. The focal length of the aspherical lens and the minimum focal length of the zoom group are determined according to the actual application and are not specifically limited in this embodiment.

[0061] Optionally, the focusing group includes at least one aspherical lens. The focusing group has a negative optical power. The focal length of the aspherical lens and the focal length of the focusing group satisfy the following relationship:

[0062] -0.08 < f1 / f a <-0.04

[0063] where f a represents the focal length of the aspherical lens, and f1 represents the focal length of the focusing group.

[0064] It should be noted that the focal length of the aspherical lens and the focal length of the focusing group are determined according to the actual application and are not specifically limited in this embodiment.

[0065] Optionally, the focal length of the variable magnification lens group can be changed by moving at least four lens groups in the variable magnification lens group, and the relationship between the minimum focal length of the variable magnification lens group and the total length of the zoom projection optical system is as follows:

[0066] 0.06 < f w / L < 0.1

[0067] where f w represents the minimum focal length of the variable magnification lens group, and L represents the total length of the zoom projection optical system.

[0068] It should be noted that the minimum focal length of the variable magnification lens group and the total length of the zoom projection optical system are determined according to actual applications, and no specific limitations are made in this embodiment. The total length of the zoom projection optical system refers to the distance from the first lens of the focusing lens group to the projection surface.

[0069] Optionally, the focal length of the variable magnification lens group can be changed by moving at least four lens groups in the variable magnification lens group, and the relationship between the minimum focal length of the variable magnification lens group and the maximum optical aperture of the zoom projection optical system is as follows:

[0070] 0.15 < f w / D < 0.35

[0071] where f w represents the minimum focal length of the variable magnification lens group, and D represents the maximum optical aperture of the zoom projection optical system.

[0072] The optical aperture refers to the effective aperture diameter that allows light to pass through in the optical system, usually referring to the physical size of the lens, mirror, or diaphragm. The maximum optical aperture refers to the maximum light passing diameter that can be achieved in a specific system or device, which directly determines the light-gathering ability, resolution, and signal-to-noise ratio of the system.

[0073] It should be noted that the minimum focal length of the variable magnification lens group and the maximum optical aperture of the zoom projection optical system are determined according to actual applications, and no specific limitations are made in this embodiment.

[0074] Optionally, by moving at least four lens groups in the variable magnification lens group, the maximum object space field angle is equal to or greater than 80 degrees.

[0075] The object space field angle refers to the maximum angular range that the lens can capture when observing from the object side. It is usually measured by the object diameter and calculated by the angle formed by two straight lines from the principal point of the lens to the edge of the field of view. The size of the object space field angle directly determines the field of view of the optical instrument; the larger the field angle, the wider the range of objects that can be captured, but some detail resolution may be sacrificed.

[0076] It should be noted that the maximum object space field angle is determined according to actual applications, and no specific limitations are made in this embodiment.

[0077] Optionally, the back focal length of the zoom projection optical system and the total length of the zoom projection optical system satisfy the following relationship:

[0078] 0.15 < FBL / L < 0.25

[0079] wherein, FBL represents the back focal length of the zoom projection optical system, and L represents the total length of the zoom projection optical system.

[0080] Taking the lens as the boundary: the space where the object is located is called the "object space"; the space where the image formed by the light emitted from the object passing through the lens is located behind the lens is called the "image space"; the focus formed in the image space is called the "image-side focus" or "back focus".

[0081] It should be noted that the back focal length of the zoom projection optical system and the total length of the zoom projection optical system are determined according to actual applications, and no specific limitations are imposed in this embodiment.

[0082] Optionally, the focusing lens group includes a first lens group, and the first lens group includes a first lens, a second lens, and a third lens; the zoom lens group includes a second lens group to a fifth lens group, the second lens group includes a fourth lens and a fifth lens, the third lens group includes a sixth lens, the fourth lens group includes a seventh lens and an eighth lens, and the fifth lens group includes a ninth lens to a twelfth lens; the fixed lens group includes a sixth lens group, and the sixth lens group includes a thirteenth lens.

[0083] It should be noted that the lens groups included in the focusing lens group, the zoom lens group, and the fixed lens group are determined according to actual applications, and no specific limitations are imposed in this embodiment. The lenses included in each lens group are determined according to applications, and no specific limitations are imposed in this embodiment.

[0084] Optionally, the first lens includes a meniscus negative power lens, the second lens includes a meniscus negative power lens, the third lens includes a biconcave negative power lens, the fourth lens includes a biconvex positive power lens, the fifth lens includes a meniscus negative power lens, the fourth lens and the fifth lens form a cemented lens, the sixth lens includes a biconvex positive power lens, the seventh lens includes a biconvex positive power lens, the eighth lens includes a biconcave negative power lens, the seventh lens and the eighth lens form a cemented lens, the ninth lens includes a biconcave negative power lens, the tenth lens includes a biconvex positive power lens, the eleventh lens includes a meniscus negative power lens, the ninth lens, the tenth lens, and the eleventh lens form a triple cemented lens, the twelfth lens includes a meniscus positive power lens, and the thirteenth lens includes a biconvex positive power lens.

[0085] It should be noted that the specific structural parameters of each lens are determined according to applications, and no specific limitations are imposed in this embodiment.

[0086] Implementing the embodiments of the present invention includes the following beneficial effects: The embodiments of the present invention include a focusing lens group, a zoom lens group, and a fixed lens group in sequence from the object side to the image side. By moving at least one lens group in the focusing lens group, a clear image can be obtained at different projection distances. By moving at least four lens groups in the zoom lens group, images of different sizes can be obtained without changing the projection distance. In addition, a variable aperture is located in one of the moving lens groups in the zoom lens group. By automatically and precisely controlling the aperture diameter, the contrast and clarity of the projected image can be improved. Thus, while achieving continuous zoom, the imaging of the image is also improved through the variable aperture, and 4K resolution can be supported.

[0087] The following uses several specific embodiments to illustrate the variable-aperture zoom projection optical system in the present invention.

[0088] Embodiment 1

[0089] Refer to Figure 2 , the variable-aperture zoom projection optical system includes a focusing lens group, a zoom lens group, and a fixed lens group in sequence from the object side to the image side. The focusing lens group includes a first lens group (G1) and the first lens group (G1) is movable. The zoom lens group includes a second lens group (G2) to a fifth lens group (G5) and all four lens groups are movable. At the same time, the variable aperture (P1) is located on the fourth lens group (G4). The fixed lens group includes a sixth lens group (G6).

[0090] The first lens group (G1) includes a first lens (L1) to a third lens (L3). Among them, the first lens (L1) is a meniscus negative-power aspherical lens, the Abbe number is between 40 and 60, and the lens diameter is less than 50 mm; the second lens (L2) is a meniscus negative-power lens, and the third lens (L3) is a biconcave negative-power lens.

[0091] The second lens group (G2) includes a fourth lens (L4) and a fifth lens (L5). Among them, the fourth lens (L4) with a biconvex positive power and the fifth lens (L5) with a meniscus negative power form a cemented lens.

[0092] The third lens group (G3) includes a sixth lens (L6). Among them, the sixth lens (L6) is a biconvex positive-power lens.

[0093] The fourth lens group (G4) includes a seventh lens (L7) and an eighth lens (L8). Among them, the seventh lens (L7) with a biconvex positive power and the eighth lens (L8) with a biconcave negative power form a cemented lens.

[0094] The fifth lens group (G5) includes the ninth lens (L9) to the twelfth lens (L12). Among them, the ninth lens (L9) with a biconcave negative optical power, the tenth lens (L10) with a biconvex positive optical power, and the eleventh lens (L11) with a meniscus negative optical power form a triple cemented lens, and the twelfth lens (L12) is a meniscus positive optical power lens.

[0095] The sixth lens group (G6) includes the thirteenth lens (L13). Among them, the thirteenth lens (L13) is a biconvex positive optical power lens.

[0096] The fourteenth lens (L14) is a prism.

[0097] The distance from the front surface vertex of the first lens (L1) to the rear surface vertex of the thirteenth lens (L13) is 91.4 mm, and the length of the entire optical system is 115 mm.

[0098] In the first embodiment, by moving the four lens groups of the zoom group, a continuous zoom system with a zoom ratio of 1.33 can be obtained. The minimum focal length is 9.5 mm, and the maximum focal length is 12.7 mm. At the same time, the full field MTF (modulation transfer function) value > 0.6, and the picture clarity is high. See Figures 3 - 4 , Figure 3 Figure Figure 4 shows the MTF diagram when the focal length of the zoom group in the first embodiment is 9.5 mm,

[0099] Table 1

[0100]

[0101]

[0102] Among them, R represents the curvature radius of the lens, d represents the lens thickness or air gap, n represents the refractive index of the glass, and v represents the Abbe number of the glass. The data of the air gaps D0 to D4 are shown in Table 2.

[0103] Table 2

[0104] Focal length 9.5 mm 12.7 mm D0 5.00 4.64 D1 12.84 4.13 D2 0.84 4.89 D3 5.01 2.19 D4 7.55 15.39

[0105] Table 2 shows the change of the air gap between the zoom groups at different focal lengths, realizing a zoom ratio of 1.33.

[0106] All the aspherical surfaces described in Table 1 are even aspherical surfaces, and their expressions are as follows:

[0107]

[0108] Wherein, z is the sag height of the vertex of the aspheric surface along the optical axis at a height of r; c represents the vertex curvature of the surface, k is the conic coefficient of the aspheric surface, and a2, a3, a4, a5, a6, a7, a8, a9 are the coefficients of the higher-order aspheric surface. The specific parameters are shown in Table III.

[0109] Table III

[0110] Surface number k Fourth - order term Sixth - order term Eighth - order term Tenth - order term Twelfth - order term Fourteenth - order term Sixteenth - order term 1 0 7.56E-05 -3.01E-07 1.07E-09 -2.82E-12 4.97E-15 -5.15E-18 -2.42E-21 2 0 9.84E-05 -4.36E-07 1.63E-09 -4.83E-12 9.72E-15 -1.12E-17 -5.56E-21

[0111] Embodiment II

[0112] Refer to Figure 5 , the variable-aperture zoom projection optical system sequentially includes a focusing lens group, a zoom lens group, and a fixed lens group from the object side to the image side. The focusing lens group includes a first lens group (G1) and the first lens group (G1) is movable. The zoom lens group includes a second lens group (G2) to a fifth lens group (G5) and the four lens groups are all movable. At the same time, a variable aperture (P1) is located on the fourth lens group (G4). The fixed lens group includes a sixth lens group (G6).

[0113] The first lens group (G1) includes a first lens (L1) to a third lens (L3). Among them, the first lens (L1) is a meniscus negative-power aspheric lens with an Abbe number between 40 and 60 and a lens aperture less than 50 mm; the second lens (L2) is a meniscus negative-power aspheric lens with an Abbe number between 40 and 60 and a lens aperture less than 40 mm; the third lens (L3) is a biconcave negative-power lens.

[0114] The second lens group (G2) includes a fourth lens (L4) and a fifth lens (L5). Among them, the biconvex positive-power fourth lens (L4) and the meniscus negative-power fifth lens (L5) form a cemented lens.

[0115] The third lens group (G3) includes a sixth lens (L6). Among them, the sixth lens (L6) is a biconvex positive-power lens.

[0116] The fourth lens group (G4) includes a seventh lens (L7) and an eighth lens (L8). Among them, the biconvex positive-power seventh lens (L7) and the biconcave negative-power eighth lens (L8) form a cemented lens.

[0117] The fifth lens group (G5) includes a ninth lens (L9) to a twelfth lens (L12). Among them, the biconcave negative-power ninth lens (L9), the biconvex positive-power tenth lens (L10), and the meniscus negative-power eleventh lens (L11) form a triple cemented lens, and the twelfth lens (L12) is a meniscus positive-power lens.

[0118] The sixth lens group (G6) includes a thirteenth lens (L13), wherein the thirteenth lens (L13) is a biconvex lens with positive optical power.

[0119] The fourteenth lens (L14) is a prism.

[0120] The distance from the vertex of the front surface of the first lens (L1) to the vertex of the rear surface of the thirteenth lens (L13) is 90.5 mm, and the length of the entire optical system is 114 mm.

[0121] In the second embodiment, by moving the four lens groups of the variable magnification group, a continuous zoom system with a zoom ratio of 1.33 can be obtained. The minimum focal length is 9.4 mm, and the maximum focal length is 12.6 mm. At the same time, the MTF value of the full field of view > 0.6, and the picture clarity is high. See Figures 6 - 7 . Figure 6 Fig. shows the MTF diagram when the focal length of the variable magnification group in the second embodiment is 9.4 mm. Figure 7 Fig. shows the MTF diagram when the focal length of the variable magnification group in the second embodiment is 12.6 mm. The optical data of the second embodiment is shown in Table IV.

[0122] Table IV

[0123]

[0124]

[0125] Among them, R represents the curvature radius of the lens, d represents the lens thickness or air gap, n represents the refractive index of the glass, and v represents the Abbe number of the glass. The data of the air gaps D0 to D4 are shown in Table V.

[0126] Table V

[0127] Focal length 9.4 mm 12.6 mm D0 5.01 4.68 D1 12.80 4.15 D2 0.80 5.77 D3 6.18 2.38 D4 5.14 12.95

[0128] Table V shows the change of the air gap between the zoom groups at different focal lengths, achieving a zoom ratio of 1.33.

[0129] All the aspherical surfaces described in Table IV are even aspherical surfaces, and their expressions are as follows:

[0130]

[0131] Among them, z is the sag height of the aspherical surface vertex when the height of the aspherical surface along the optical axis is r, c represents the vertex curvature of the surface, k is the conic coefficient of the aspherical surface, and a2, a3, a4, a5, a6, a7, a8, a9 are the high-order aspherical coefficients. For specific parameters, see Table VI.

[0132] Table VI

[0133] Surface number k Fourth - order term Sixth - order term Eighth - order term Tenth - order term Twelfth - order term Fourteenth - order term Sixteenth - order term 1 0 9.64E-05 -3.52E-07 1.11E-09 -2.63E-12 4.30E-15 -4.25E-18 0.00E+00 2 0 1.35E-04 -5.04E-07 1.54E-09 -4.75E-12 9.30E-15 -8.28E-18 0.00E+00 3 0 8.23E-05 1.57E-07 3.79E-11 -6.76E-13 7.42E-16 7.29E-18 0.00E+00 4 0 -1.38E-04 -6.28E-08 -1.15E-09 -1.86E-11 9.23E-14 -6.65E-16 0.00E+00

[0134] Embodiment 3

[0135] Referring to Figure 8 , in the variable-aperture zoom projection optical system, from the object side to the image side, there are a focusing lens group, a variable magnification lens group, and a fixed lens group in sequence. The focusing lens group includes a first lens group (G1) and the first lens group (G1) is movable. The variable magnification lens group includes a second lens group (G2) to a fifth lens group (G5) and the four lens groups are all movable, and at the same time, a variable aperture (P1) is located on the fourth lens group (G4). The fixed lens group includes a sixth lens group (G6).

[0136] The first lens group (G1) includes a first lens (L1) to a third lens (L3). Among them, the first lens (L1) is a meniscus negative-power aspherical lens, the Abbe number is between 40 and 60, and the lens aperture is less than 50 mm. The second lens (L2) is a meniscus negative-power lens, and the third lens (L3) is a biconcave negative-power lens.

[0137] The second lens group (G2) includes a fourth lens (L4) and a fifth lens (L5). Among them, the fourth lens (L4) with a biconvex positive power and the fifth lens (L5) with a meniscus negative power form a cemented lens.

[0138] The third lens group (G3) includes a sixth lens (L6). Among them, the sixth lens (L6) is a biconvex positive-power lens.

[0139] The fourth lens group (G4) includes a seventh lens (L7) and an eighth lens (L8). Among them, the seventh lens (L7) with a biconvex positive power and the eighth lens (L8) with a biconcave negative power form a cemented lens.

[0140] The fifth lens group (G5) includes a ninth lens (L9) to a twelfth lens (L12). Among them, the ninth lens (L9) with a biconcave negative power, the tenth lens (L10) with a biconvex positive power, and the eleventh lens (L11) with a meniscus negative power form a triple cemented lens, and the twelfth lens (L12) is a meniscus positive-power aspherical lens, and the Abbe number is between 50 and 90.

[0141] The sixth lens group (G6) includes a thirteenth lens (L13). Among them, the thirteenth lens (L13) is a biconvex positive-power lens.

[0142] The fourteenth lens (L14) is a prism.

[0143] The distance from the front surface vertex of the first lens (L1) to the rear surface vertex of the thirteenth lens (L13) is 91.4 mm, and the length of the entire optical system is 115 mm.

[0144] In Embodiment 3, by moving the four lens groups of the variable magnification group, a continuous zoom system with a zoom ratio of 1.33 can be obtained. The minimum focal length is 9.4 mm, and the maximum focal length is 12.6 mm. At the same time, the MTF value of the full field of view > 0.6, and the picture clarity is high. See Figures 9 - 10 , Figure 9 Figure MTF diagram when the focal length of the variable magnification group in Embodiment 3 is 9.4 mm, Figure 10 Figure MTF diagram when the focal length of the variable magnification group in Embodiment 3 is 12.6 mm. Optical data table VII of Embodiment 3.

[0145] Table VII

[0146]

[0147]

[0148] Among them, R represents the curvature radius of the lens, d represents the lens thickness or air gap, n represents the refractive index of the glass, and v represents the Abbe number of the glass. The data of the air gaps D0 to D4 are shown in Table VIII.

[0149] Table VIII

[0150] Focal length 9.4 mm 12.6 mm D0 5.06 4.95 D1 13.15 3.46 D2 0.80 5.44 D3 5.01 2.04 D4 4.51 12.64

[0151] Table VIII shows the changes in the air gaps between the zoom groups at different focal lengths, achieving a zoom ratio of 1.33.

[0152] All the aspherical surfaces described in Table VII are even aspherical surfaces, and their expressions are as follows:

[0153]

[0154] Among them, z is the sag height of the aspherical surface vertex along the optical axis direction at a height of r, c represents the vertex curvature of the surface, k is the conic coefficient of the aspherical surface, and a2, a3, a4, a5, a6, a7, a8, a9 are the high-order aspherical coefficients. See Table IX for details.

[0155] Table IX

[0156] Surface number k Fourth - order term Sixth - order term Eighth - order term Tenth - order term Twelfth - order term Fourteenth - order term Sixteenth - order term 1 0 7.66E-05 -3.01E-07 1.06E-09 -2.66E-12 4.48E-15 -4.42E-18 7.66E-05 2 0 1.03E-04 -4.56E-07 1.70E-09 -4.78E-12 8.78E-15 -8.89E-18 1.03E-04 20 0 1.06E-05 1.73E-08 2.51E-11 2.47E-14 0.00E+00 0.00E+00 1.06E-05 21 0 1.82E-06 -6.71E-10 1.73E-10 -1.03E-12 0.00E+00 0.00E+00 1.82E-06

[0157] Embodiment 4

[0158] Refer to Figure 11 , the variable-aperture zoom projection optical system from the object side to the image side is in turn a fixed group, a variable magnification group, and a focusing group. The fixed group contains the first lens group (G1). The variable magnification group contains the second lens group (G2) to the fifth lens group (G5), and the four lens groups are all movable. At the same time, the variable aperture (P1) is located on the fourth group (G4). The focusing group contains the sixth lens group (G6), and the sixth lens group (G6) is movable.

[0159] The first lens group (G1) includes a first lens (L1) to a third lens (L3). Among them, the first lens (L1) is a meniscus negative-power aspherical lens, with an Abbe number between 40 and 60, and the lens aperture is less than 50 mm. The second lens (L2) is a meniscus negative-power lens, and the third lens (L3) is a biconcave negative-power lens.

[0160] The second lens group (G2) includes a fourth lens (L4) and a fifth lens (L5). Among them, the fourth lens (L4) with a biconvex positive power and the fifth lens (L5) with a meniscus negative power form a cemented lens.

[0161] The third lens group (G3) includes a sixth lens (L6). Among them, the sixth lens (L6) is a biconvex positive-power lens.

[0162] The fourth lens group (G4) includes a seventh lens (L7) and an eighth lens (L8). Among them, the seventh lens (L7) with a biconvex positive power and the eighth lens (L8) with a biconcave negative power form a cemented lens.

[0163] The fifth lens group (G5) includes a ninth lens (L9) to a twelfth lens (L12). Among them, the ninth lens (L9) with a biconcave negative power, the tenth lens (L10) with a biconvex positive power, and the eleventh lens (L11) with a meniscus negative power form a triple cemented lens, and the twelfth lens (L12) is a meniscus positive-power lens.

[0164] The sixth lens group (G6) includes a thirteenth lens (L13). Among them, the thirteenth lens (L13) is a biconvex positive-power lens.

[0165] The fourteenth lens (L14) is a prism.

[0166] The distance from the front surface vertex of the first lens (L1) to the rear surface vertex of the thirteenth lens (L13) is 91.4 mm, and the length of the entire optical system is 115 mm.

[0167] In the fourth embodiment of this patent, by moving the four lens groups of the varifocal group, a continuous zoom system with a zoom ratio of 1.33 can be obtained. The minimum focal length is 9.4 mm, and the maximum focal length is 12.6 mm. At the same time, the MTF value of the full field of view > 0.6, and the picture clarity is high. See Figures 12 - 13 , Figure 12 which shows the MTF schematic diagram when the focal length of the varifocal group in the fourth embodiment is 9.4 mm, Figure 13 and which shows the MTF schematic diagram when the focal length of the varifocal group in the fourth embodiment is 12.6 mm. The optical data of the fourth embodiment is shown in Table X.

[0168] Table X

[0169]

[0170]

[0171] Among them, R represents the curvature radius of the lens, d represents the lens thickness or air gap, n represents the refractive index of the glass, and v represents the Abbe number of the glass. The data of the air gap D0 to D4 are shown in Table XI.

[0172] Table XI

[0173] Focal length 9.4 mm 12.6 mm D0 5.00 4.70 D1 11.71 2.81 D2 0.80 4.74 D3 4.73 2.03 D4 5.77 13.73

[0174] Table XI shows the change of the air gap between the zoom groups at different focal lengths, achieving a zoom ratio of 1.33 times.

[0175] The aspherical surfaces described in Table X are all even aspherical surfaces, and their expressions are as follows:

[0176]

[0177] Among them, z is the sag height of the vertex of the aspherical surface when the aspherical surface is along the optical axis direction at a height of r, c represents the vertex curvature of the surface, k is the conic coefficient of the aspherical surface, and a2, a3, a4, a5, a6, a7, a8, a9 are the coefficients of the high-order aspherical surface.

[0178] Table XII

[0179] Surface number k Fourth - order term Sixth - order term Eighth - order term Tenth - order term Twelfth - order term Fourteenth - order term Sixteenth - order term 1 0 7.69E-05 -2.99E-07 1.06E-09 -2.66E-12 4.43E-15 -4.33E-18 1.93E-21 2 0 1.02E-04 -4.53E-07 1.72E-09 -4.85E-12 8.75E-15 -8.70E-18 3.58E-21

[0180] The above is a specific description of the preferred embodiment of the present invention. However, the present invention is not limited to the described embodiment. Those skilled in the art can make various equivalent deformations or substitutions without departing from the spirit of the present invention, and these equivalent deformations or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A variable-aperture zoom projection optical system, characterized in that, From the object side to the image side, it sequentially includes a focusing group, a zooming group, and a fixed group. The focusing group includes at least one movable lens group, and the zooming group includes a variable aperture and at least four movable lens groups; wherein, The focusing group is used to obtain a clear image by moving at least one lens group under different projection distances; The zooming group is used to obtain images of different sizes by moving at least four lens groups without changing the projection distance; The fixed group is used for the assembly of the zoom projection optical system.

2. The zoom projection optical system according to claim 1, characterized in that, By moving at least four lens groups in the zooming group, the focal length of the zooming group can be changed, and the minimum focal length and the maximum focal length of the zooming group satisfy the following relationship: 1.2 < f t / f w <1.5 where f t represents the maximum focal length of the zoom group, and f w represents the minimum focal length of the zoom group.

3. The zoom projection optical system according to claim 1, wherein The focusing group includes at least one aspherical lens. By moving at least four lens groups in the zooming group, the focal length of the zooming group can be changed, and the focal length of the aspherical lens and the minimum focal length of the zooming group satisfy the following relationship: -0.1 < f w / f a < -0.05 where f a represents the focal length of the aspherical lens, and f w represents the minimum focal length of the zoom group.

4. The zoom projection optical system according to claim 1, characterized in that, The focusing group includes at least one aspherical lens, and the focusing group has a negative optical power. The focal length of the aspherical lens and the focal length of the focusing group satisfy the following relationship: -0.08 < f1 / f a < -0.04 Among them, f a represents the focal length of the aspherical lens, and f1 represents the focal length of the focusing lens group.

5. The zoom projection optical system according to claim 1, wherein By moving at least four lens groups in the zooming group, the focal length of the zooming group can be changed, and the minimum focal length of the zooming group and the total length of the zoom projection optical system satisfy the following relationship: 0.06 < f w / L < 0.1 Among them, f w represents the minimum focal length of the variable magnification lens group, and L represents the total length of the zoom projection optical system.

6. The zoom projection optical system according to claim 1, wherein By moving at least four lens groups in the zooming group, the focal length of the zooming group can be changed, and the minimum focal length of the zooming group and the maximum optical aperture of the zoom projection optical system satisfy the following relationship: 0.15 < f w / D < 0.35 where f w represents the minimum focal length of the variable magnification lens group, and D represents the maximum optical aperture of the zoom projection optical system.

7. The zoom projection optical system according to claim 1, characterized in that, By moving at least four lens groups in the zooming group, the maximum object field angle obtained is equal to or greater than 80 degrees.

8. The zoom projection optical system according to claim 1, wherein The back focal length of the zoom projection optical system and the total length of the zoom projection optical system satisfy the following relationship: 0.15 < FBL / L < 0.25 Wherein, FBL represents the back focal length of the zoom projection optical system, and L represents the total length of the zoom projection optical system.

9. The zoom projection optical system according to claim 1, wherein, The focusing group includes a first lens group, and the first lens group includes a first lens, a second lens, and a third lens; the zooming group includes a second lens group to a fifth lens group. The second lens group includes a fourth lens and a fifth lens, the third lens group includes a sixth lens, the fourth lens group includes a seventh lens and an eighth lens, and the fifth lens group includes a ninth lens to a twelfth lens; the fixed group includes a sixth lens group, and the sixth lens group includes a thirteenth lens.

10. The zoom projection optical system according to claim 9, wherein, The first lens includes a meniscus negative power lens, the second lens includes a meniscus negative power lens, the third lens includes a biconcave negative power lens, the fourth lens includes a biconvex positive power lens, the fifth lens includes a meniscus negative power lens, the fourth lens and the fifth lens form a cemented lens, the sixth lens includes a biconvex positive power lens, the seventh lens includes a biconvex positive power, the eighth lens includes a biconcave negative power lens, the seventh lens and the eighth lens form a cemented lens, the ninth lens includes a biconcave negative power lens, the tenth lens includes a biconvex positive power lens, the eleventh lens includes a meniscus negative power lens, the ninth lens, the tenth lens and the eleventh lens form a triple cemented lens, the twelfth lens includes a meniscus positive power lens, and the thirteenth lens includes a biconvex positive power lens.

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