Large-aperture zoom projection lens

Abstract

The invention discloses a large-aperture zoom projection lens, which relates to the technical field of projection lenses and comprises a first lens group, a second lens group, a third lens group, a fourth lens group, a fifth lens group, a sixth lens group and a seventh lens group which are sequentially arranged from an amplification side to a reduction side along an optical axis. The first lens group and the seventh lens group are fixed, and the lens groups further meet the following conditional expressions: 4.5 < = f1 / fw < = 6.0, 6.0 < = f2 / fw < = 7.3, 1.2 < = f3 / fw < = 2.5, 0.9 < = f7 / fw < = 1.8, f1 being the focal length of the first lens group, f2 being the focal length of the second lens group, f3 being the focal length of the third lens group, f7 being the focal length of the seventh lens group, and fw being the focal length of the lens at the wide-angle end. According to the large-aperture zooming projection lens, after zooming is carried out under specific specification parameters, refocusing is not needed, a projection picture is still kept clear, and zooming is more convenient.

Description

Technical Field

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

[0002] Projection lenses, used in projection devices such as projectors, magnify small images and project them onto a screen or wall. Different users may have different projection magnification requirements at the same projection distance. Zooming the projection lens can change this magnification. However, with certain projection lenses, such as the one disclosed in Publication No. CN119224988A, zooming without changing the projection distance can cause the projected image to become blurred, requiring refocusing to restore clarity. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a large aperture zoom projection lens that, within specific specifications, can maintain a clear projection image after zooming without the need for refocusing, making zooming more convenient.

[0004] A large aperture zoom projection lens according to an embodiment of the present invention includes a first lens group, a second lens group, a third lens group, a fourth lens group, a fifth lens group, a sixth lens group, and a seventh lens group, which are arranged in sequence from the magnification side to the reduction side along the optical axis; the first lens group and the seventh lens group are both fixed, and the first lens group, the second lens group, the third lens group, and the seventh lens group further satisfy the following conditional formula:

[0005] 4.5≤f1 / fw≤6.0,

[0006] 6.0≤|f2| / fw≤7.3,

[0007] 1.2≤|f3| / fw≤2.5,

[0008] 0.9≤|f7| / fw≤1.8,

[0009] Among them, f1 is the focal length of the first lens group, f2 is the focal length of the second lens group, f3 is the focal length of the third lens group, f7 is the focal length of the seventh lens group, and fw is the focal length of the lens at the wide-angle end.

[0010] The large aperture zoom projection lens according to the embodiment of the present invention has at least the following beneficial effects: the projection lens adopts the structure provided by the present invention and satisfies the conditions 4.5≤f1 / fw≤6.0, 6.0≤|f2| / fw≤7.3, 1.2≤|f3| / fw≤2.5, and 0.9≤|f7| / fw≤1.8. Therefore, the projection lens can achieve a clear projection image without refocusing after a zoom operation without changing the projection distance. Furthermore, the first lens group and the seventh lens group are both fixed, and the total length of the projection lens does not change during a zoom operation, which is conducive to simplifying the lens structure design of the projection equipment and achieving better dust and water resistance.

[0011] According to some embodiments of the present invention, the lens further satisfies the following conditional formula:

[0012] 1.5≤BF / fw≤1.8,

[0013] Among them, BF is the equivalent air length of the back focus of the lens, and fw is the focal length of the lens at the wide-angle end.

[0014] According to some embodiments of the present invention, the second lens group is a focusing group.

[0015] According to some embodiments of the present invention, during a focusing process of the magnification side of the lens from infinity to a close distance, the second lens group moves along the optical axis from the reduction side toward the magnification side.

[0016] According to some embodiments of the present invention, the third lens group, the fourth lens group, the fifth lens group, and the sixth lens group are all zoom groups, and the third lens group, the fourth lens group, the fifth lens group, and the sixth lens group are all capable of moving independently along the optical axis.

[0017] According to some embodiments of the present invention, during a zooming process in which the effective focal length of the lens is changed from short to long, the third lens group moves along the optical axis from the magnification side toward the reduction side.

[0018] According to some embodiments of the present invention, the zooming process of the effective focal length of the lens from short to long includes a first zoom section and a second zoom section. In the first zoom section, the fourth lens group moves along the optical axis from the reduction side toward the magnification side. In the second zoom section, the fourth lens group moves along the optical axis from the magnification side toward the reduction side.

[0019] According to some embodiments of the present invention, during a zooming process of the effective focal length of the lens from short to long, the fifth lens group moves along the optical axis from the reduction side toward the magnification side.

[0020] According to some embodiments of the present invention, during a zooming process of the effective focal length of the lens from short to long, the sixth lens group moves along the optical axis from the reduction side toward the magnification side.

[0021] According to some embodiments of the present invention, during the zooming process of the lens, the aperture of the lens remains constant.

[0022] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0024] Figure 1 Schematic diagram of the structure of a large aperture zoom projection lens at the Wide end according to an embodiment of the present invention;

[0025] Figure 2 This is a schematic structural diagram of a large aperture zoom projection lens at the middle end according to an embodiment of the present invention;

[0026] Figure 3 This is a schematic structural diagram of a large aperture zoom projection lens at the Tele end according to an embodiment of the present invention;

[0027] Figure 4 This is a light aberration diagram of the large aperture zoom projection lens at the Wide end according to an embodiment of the present invention;

[0028] Figure 5 Graphs showing spherical aberration, astigmatism, field curvature, and distortion of the large aperture zoom projection lens at the Wide end of an embodiment of the present invention;

[0029] Figure 6 This is a light aberration diagram of the large aperture zoom projection lens at the middle end of an embodiment of the present invention;

[0030] Figure 7 Graphs showing spherical aberration, astigmatism, field curvature, and distortion of the large aperture zoom projection lens at the middle end of an embodiment of the present invention;

[0031] Figure 8 This is a light aberration diagram of the large aperture zoom projection lens at the Tele end according to an embodiment of the present invention;

[0032] Figure 9 Graphs showing spherical aberration, astigmatism, field curvature, and distortion of the large aperture zoom projection lens at the Tele end according to an embodiment of the present invention.

[0033] Figure Number:

[0034] A first lens group 100 , a second lens group 200 , a third lens group 300 , a fourth lens group 400 , a fifth lens group 500 , a sixth lens group 600 , and a seventh lens group 700 . DETAILED DESCRIPTION

[0035] The following describes embodiments of the present invention in detail. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended only to explain the present invention and are not to be construed as limiting the present invention.

[0036] In the description of the present invention, it should be understood that descriptions involving orientation, such as the orientation or positional relationship indicated by up, down, etc., are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0037] In the description of the present invention, "a plurality" refers to more than two. The use of "first" or "second" is solely for the purpose of distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of the indicated technical features, or implicitly indicating the order of the indicated technical features.

[0038] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, and connecting should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0039] As described in the background art, a home projector is used as an example. After the home projector is fixedly installed, a screen is set 3 meters in front of the projector, that is, the projection distance is 3 meters. An 80-inch screen is projected on the screen, and after focusing, a clear image is obtained. When the projection distance remains at 3 meters, the projection lens is zoomed to adjust the size of the projected image, for example, to enlarge the projected image to 100 inches. After the zoom operation of the projection lens of the prior art, the image will become blurred and needs to be refocused to obtain a clear image again. However, the focusing operation of the projection lens is relatively complicated. Although the prior art can achieve automatic focus, the effect of automatic focus is not satisfactory. In the end, manual fine-tuning is still required to obtain the best picture clarity. If the projection lens needs to be refocused every time it is zoomed, it will affect the user experience.

[0040] Reference Figure 1As shown, a large aperture zoom projection lens according to an embodiment of the present invention includes a first lens group 100, a second lens group 200, a third lens group 300, a fourth lens group 400, a fifth lens group 500, a sixth lens group 600, and a seventh lens group 700, which are arranged in sequence from the magnification side to the reduction side along the optical axis; the first lens group 100 and the seventh lens group 700 are both fixed, and the first lens group 100, the second lens group 200, the third lens group 300, and the seventh lens group 700 further satisfy the following conditional formula:

[0041] 4.5≤f1 / fw≤6.0,

[0042] 6.0≤|f2| / fw≤7.3,

[0043] 1.2≤|f3| / fw≤2.5,

[0044] 0.9≤|f7| / fw≤1.8,

[0045] Wherein, f1 is the focal length of the first lens group 100, f2 is the focal length of the second lens group 200, f3 is the focal length of the third lens group 300, f7 is the focal length of the seventh lens group 700, and fw is the focal length of the lens at the wide-angle end.

[0046] The projection lens structure of the embodiment of the present invention allows for a clear image to be obtained even after zooming, while maintaining a constant projection distance, without the need for refocusing. This significantly reduces the complexity of user operations and improves the user experience. It should be understood that, as a projection lens, the magnification side refers to the projection image side, where the screen is located, and the reduction side refers to the projector output image side, where the prism group is located on the side of the seventh lens group 700.

[0047] It can be understood that the first lens group 100 and the seventh lens group 700 are both fixed, and the total length of the lens will not change during the zooming process, which means that there is no need to set an adjustment device at the lens installation position of the projector to adapt to the change in lens length, that is, the structure of the projector can be simplified in design, and better dust and water proofing effects can be achieved.

[0048] It should be understood that the lens group can be composed of one lens or multiple lenses, and the present invention does not limit the number of lenses in a single lens group.

[0049] Preferably, the lens also satisfies the following conditional formula:

[0050] 1.5≤BF / fw≤1.8,

[0051] Among them, BF is the equivalent air length of the back focus of the lens, and fw is the focal length of the lens at the wide-angle end.

[0052] Preferably, second lens group 200 is a focusing group. During the focusing process of the magnification side of the lens from infinity to close distance, second lens group 200 moves along the optical axis from the reduction side toward the magnification side. Close distance here is relative to infinity, emphasizing the direction from infinity to close distance. It should be understood that no matter how many values ​​are defined as close distance, the directionality of the direction from infinity to close distance will not change.

[0053] It should be understood that second lens group 200, as a focusing group, can be used for focusing when the projection distance changes. During initial projection, or when the projection distance changes, second lens group 200 is required for focusing to obtain a clear projected image. Subsequent zoom operations, while maintaining the projection distance, do not require further adjustment of the second lens group 200, i.e., no further focusing operations are required.

[0054] Preferably, the third lens group 300 , the fourth lens group 400 , the fifth lens group 500 and the sixth lens group 600 are all zoom groups, and the third lens group 300 , the fourth lens group 400 , the fifth lens group 500 and the sixth lens group 600 can move independently along the optical axis.

[0055] Preferably, the zooming process of the effective focal length of the lens from short to long includes a first zoom section and a second zoom section. In the first zoom section, the fourth lens group 400 moves along the optical axis from the reduction side toward the magnification side. In the second zoom section, the fourth lens group 400 moves along the optical axis from the magnification side toward the reduction side. In the entire zooming process of the effective focal length of the lens from short to long, the third lens group 300 moves along the optical axis from the magnification side toward the reduction side; the fifth lens group 500 moves along the optical axis from the reduction side toward the magnification side; and the sixth lens group 600 moves along the optical axis from the reduction side toward the magnification side.

[0056] Preferably, the aperture of the lens remains constant during the zooming process. In some existing projection lenses, when the zooming process is in progress, the lens is in the short focus position (wide-angle end), the aperture increases, and the lens is in the telephoto position, the aperture decreases, resulting in excessive loss of light energy passing through the lens. If the lens aperture is controlled to remain constant during the zooming process, the loss of light energy can be reduced. The lens structure of the embodiment of the present invention, through reasonable optical power lens and lens group design, maintains a constant ratio of the lens focal length to the entrance pupil diameter during the zooming process, thereby achieving a constant aperture during the zooming process.

[0057] Example 1:

[0058] The effective focal length (EFL) of the lens is 15.1mm at the wide end to 45.3mm at the tele end. The aperture (Fno) is 1.7. The full field of view (2ω) is 31.9°. The lens also satisfies the following conditional equation:

[0059] f1 / fw=5.43, |f2| / fw=6.81, |f3| / fw=1.78, f7 / fw=1.30, BF / fw=1.95.

[0060] The remaining parameters of the projection lens of Example 1 are shown in Table 1. The optical structure is shown in Figures 1 to 3 shown.

[0061] Table 1 Parameters of the optical lens of Example 1

[0062]

[0063]

[0064] When the lens of Example 1 is focused, the interval data is shown in Table 2.

[0065] Table 2 Lens spacing data of Example 1

[0066] FAR Middle Near D0 1500 3000 7000 D1 0.5 1.91 4.52 D2 13.42 12.55 15.16

[0067] When the lens of Example 1 is zooming, the zoom interval data is shown in Table 3.

[0068] Table 3 Zoom interval data of the lens of Example 1

[0069] Wide Middle Tele D2 12.55 16.65 16.87 D3 29.55 4.09 1.70 D4 4.13 10.88 0.5 D5 0.5 4.29 9.07 D6 0.5 11.32 19.08

[0070] D0 to D6 in Tables 2 and 3 are the same as D0 to D6 in Table 1.

[0071] The light aberration of the lens of Example 1 at the Wide end is as follows: Figure 4 As shown; spherical aberration, astigmatism field curvature, and distortion diagrams are shown in Figure 5 As shown. The light aberration of the lens of Example 1 at the middle end is as follows Figure 6 As shown; spherical aberration, astigmatism field curvature, and distortion diagrams are shown in Figure 7 The light aberration of the lens of Example 1 at the Tele end is as follows: Figure 8 As shown; spherical aberration, astigmatism field curvature, and distortion diagrams are shown in Figure 9 shown.

[0072] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the scope of the present invention.

Claims

1. A large aperture zoom projection lens, characterized in that: include: A first lens group (100), a second lens group (200), a third lens group (300), a fourth lens group (400), a fifth lens group (500), a sixth lens group (600) and a seventh lens group (700) are sequentially arranged along the optical axis from the magnification side to the reduction side; The first lens group (100) and the seventh lens group (700) are both fixed, and the first lens group (100), the second lens group (200), the third lens group (300) and the seventh lens group (700) further satisfy the following conditional formula: 4.5≤f1 / fw≤6.0, 6.0≤|f2| / fw≤7.3, 1.2≤|f3| / fw≤2.5, 0.9≤|f7| / fw≤1.8, Wherein, f1 is the focal length of the first lens group (100), f2 is the focal length of the second lens group (200), f3 is the focal length of the third lens group (300), f7 is the focal length of the seventh lens group (700), and fw is the focal length of the lens at the wide-angle end.

2. The large aperture zoom projection lens according to claim 1, wherein: The lens also meets the following conditions: 1.5≤BF / fw≤1.8, Among them, BF is the equivalent air length of the back focus of the lens, and fw is the focal length of the lens at the wide-angle end.

3. The large aperture zoom projection lens according to claim 1, wherein: The second lens group (200) is a focusing group.

4. The large aperture zoom projection lens according to claim 3, wherein: During the focusing process of the magnification side of the lens from infinity to a close distance, the second lens group (200) moves along the optical axis from the reduction side toward the magnification side.

5. The large aperture zoom projection lens according to claim 1, wherein: The third lens group (300), the fourth lens group (400), the fifth lens group (500) and the sixth lens group (600) are all zoom groups, and the third lens group (300), the fourth lens group (400), the fifth lens group (500) and the sixth lens group (600) are all capable of moving independently of each other along the optical axis.

6. The large aperture zoom projection lens according to claim 5, wherein: During the zooming process of the effective focal length of the lens from short to long, the third lens group (300) moves along the optical axis from the magnification side toward the reduction side.

7. The large aperture zoom projection lens according to claim 5, wherein: The zoom process of the lens from short to long effective focal length includes a first zoom section and a second zoom section. In the first zoom section, the fourth lens group (400) moves along the optical axis from the reduction side toward the magnification side. In the second zoom section, the fourth lens group (400) moves along the optical axis from the magnification side toward the reduction side.

8. The large aperture zoom projection lens according to claim 5, wherein: During the zooming process of the effective focal length of the lens from short to long, the fifth lens group (500) moves along the optical axis from the reduction side toward the magnification side.

9. The large aperture zoom projection lens according to claim 5, wherein: During the zooming process of the effective focal length of the lens from short to long, the sixth lens group (600) moves along the optical axis from the reduction side toward the magnification side.

10. The large aperture zoom projection lens according to claim 1, wherein: During the zooming process of the lens, the aperture of the lens remains constant.

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