High-magnification continuous zooming projection optical system

Abstract

The invention discloses a high-magnification continuous zooming projection optical system, which relates to the technical field of light projection and can obtain clear pictures under different projection distances by moving at least two lens groups of a focusing group. By moving the at least five lens groups of the zoom group, pictures of different sizes can be obtained without changing the projection distance. The diaphragm is located in one of the lens groups of the zoom group, the angle of light passing through the diaphragm is controlled when at least five lens groups of the zoom group move, and the change of the whole system FNumber before and after movement is reduced, so that the change of the brightness of a projection picture in the zooming process is reduced. Through the mutual cooperation of the lens groups, high-magnification continuous zooming can be realized, the imaging quality is high, the image distortion is small, and the resolution is clear.

Description

Technical Field

[0001] The invention relates to the technical field of light projection, and in particular to a large-magnification continuous zoom projection optical system. Background Art

[0002] Laser display projection technology is a new type of display projection technology on the market. Laser projectors that currently use this technology can achieve the function of automatic focusing, and laser projectors that can achieve the automatic focusing function are also called automatic focusing projectors. Among them, focusing refers to adjusting the position of the projector's focal point to adjust the projector's image distance.

[0003] The focus projector includes a driving component and a projection lens, wherein the projection lens includes a focus group for focusing. When the projection lens projects onto a screen and the distance between the projection lens and the screen changes, the driving component can control each focus lens in the focus group to move along the optical axis of the focus group according to a pre-configured correspondence between the distance and the image distance.

[0004] With the development of projection technology, the application scenarios of projectors are becoming more and more diverse. When users need to project a large image at a short distance, they will choose a short-throw lens. Traditional short-throw lenses are mainly fixed-focus, and different image sizes can only be achieved by changing the projection distance, which is difficult to meet the increasing complex needs of users. In addition, the zoom ratio of traditional zoom projection lenses is mainly concentrated between 1.2x and 1.6x, and a single lens is difficult to meet the increasing needs of users. Summary of the invention

[0005] The invention provides a large-magnification continuous zoom projection optical system.

[0006] The present invention provides the following scheme:

[0007] A large-magnification continuous zoom projection optical system comprises a focus group, a zoom group and a fixed group in sequence from the object side to the image side along the optical axis direction;

[0008] The focus adjustment group at least includes a first lens group and a second lens group, both of which are movable along the optical axis, and at least one of the first lens group and the second lens group is moved so as to obtain a clear picture at different projection distances;

[0009] The zoom group at least includes a third lens group, a fourth lens group, a fifth lens group, a sixth lens group and a seventh lens group, all of which are movable along the optical axis direction; at least one of the third lens group, the fourth lens group, the fifth lens group, the sixth lens group and the seventh lens group is moved so as to obtain images of different sizes without changing the projection distance;

[0010] The fixed group includes at least one meniscus-type positive power lens;

[0011] Among them, the aperture is located in any lens group in the zoom group, so that when the lens group in the zoom group moves, the angle of the light passing through the aperture is controlled, the change of the F Number of the entire system before and after the movement is reduced, and the purpose of reducing the change of the projection picture brightness during the zoom process is achieved.

[0012] Preferably, the first lens group has positive focal power, and the second lens group has negative focal power; the focal length f1 of the first lens group and the focal length f2 of the second lens group satisfy the following relationship: -0.4 <f2 / f1<-0.1。

[0013] Preferably: the first lens group includes a first lens and a second lens; the first lens is a biconvex positive power lens, and the second lens is a meniscus negative power lens;

[0014] The second lens group includes a third lens, a fourth lens, a fifth lens and a sixth lens; the third lens is a meniscus type negative power lens, the fourth lens is a biconcave type negative power lens, the fifth lens is a biconcave type negative power lens, and the sixth lens is a meniscus type positive power lens.

[0015] Preferably, the minimum focal length fw obtained by moving at least five lens groups of the zoom group and the maximum focal length ft obtained by moving at least five lens groups of the zoom group satisfy the following relationship: 1.8 <ft / fw<2.2。

[0016] Preferably, the maximum aperture F#w obtained by moving at least five lens groups of the zoom group and the minimum aperture F#t obtained by moving at least five lens groups of the zoom group satisfy the following relationship: <F#w / F#t<1.15。

[0017] Preferably, the minimum focal length fw obtained by moving at least five lens groups of the zoom group and the total length TTL of the entire optical system satisfy the following relationship: 0.08 <fw / TTL<0.12。

[0018] Preferably, the maximum field of view FOV obtained by moving at least five lens groups of the zoom group satisfies the following relationship: 40° <FOV<60°。

[0019] Preferably, the back focus FBL of the optical system and the total length TTL of the entire optical projection system satisfy the following relationship: 0.2 <FBL / TTL<0.3。

[0020] Preferably: the third lens group includes a seventh lens; the seventh lens is a biconvex positive power lens;

[0021] The fourth lens group includes an eighth lens; the eighth lens is a meniscus-type positive power lens;

[0022] The fifth lens group includes a ninth lens; the ninth lens is a biconcave lens with negative optical power;

[0023] The sixth lens group includes a tenth lens and an eleventh lens; the tenth lens with a biconcave negative focal power and the eleventh lens with a biconvex positive focal power form a cemented lens;

[0024] The seventh lens group includes a twelfth lens, a thirteenth lens, a fourteenth lens, a fifteenth lens and a sixteenth lens; the twelfth lens of meniscus type negative focal power, the thirteenth lens of biconvex type positive focal power and the fourteenth lens of meniscus type negative focal power form a triple cemented lens, the fifteenth lens is a biconvex type positive focal power lens, and the sixteenth lens is a meniscus type positive focal power lens.

[0025] Preferably, the fixed lens group includes an eighth lens group, the eighth lens group includes a seventeenth lens, and the seventeenth lens is a meniscus-type positive power lens.

[0026] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0027] Through the present invention, a large-magnification continuous zoom projection optical system can be realized. In one implementation mode, the system can obtain a clear picture at different projection distances by moving at least two lens groups of the focus group. By moving at least five lens groups of the zoom group, pictures of different sizes can be obtained without changing the projection distance. The diaphragm is located in one of the lens groups of the zoom group. When the at least five lens groups of the zoom group move, the angle of the light passing through the diaphragm is controlled to reduce the change of the F Number of the entire system before and after the movement, thereby reducing the change of the brightness of the projection picture during the zooming process. Through the mutual cooperation of the lens groups, a large-magnification continuous zoom can be achieved while achieving high imaging quality, small picture distortion and clear resolution.

[0028] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1It is a structural schematic diagram of a large-magnification continuous zoom projection optical system provided by an embodiment of the present invention;

[0031] Figure 2 is a schematic diagram of the focal lengths of 24 mm and 48 mm provided by an embodiment of the present invention;

[0032] Figure 3 1 is a schematic diagram of MTF when the focal length is 24 mm and the maximum field angle is 53° provided by an embodiment of the present invention;

[0033] Figure 4 is a distortion curve diagram provided by an embodiment of the present invention when the focal length is 24 mm and the maximum field of view angle is 53°;

[0034] Figure 5 1 is a schematic diagram of MTF when the focal length is 48 mm and the maximum field angle is 28° provided by an embodiment of the present invention;

[0035] Figure 6 This is a distortion curve provided by an embodiment of the present invention when the focal length is 48 mm and the maximum field of view angle is 28°. DETAILED DESCRIPTION

[0036] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 belong to the scope of protection of the present invention.

[0037] Example

[0038] See also Figure 1 , is a large-magnification continuous zoom projection optical system provided by an embodiment of the present invention, such as Figure 1 As shown, the system may include a focus group, a zoom group and a fixed group in sequence from the object side to the image side along the optical axis direction;

[0039] The focusing group at least includes a first lens group G1 and a second lens group G2, both of which are movable along the optical axis, and at least one of the first lens group G1 and the second lens group G2 is moved so as to obtain a clear picture at different projection distances;

[0040] The zoom group at least includes a third lens group G3, a fourth lens group G4, a fifth lens group G5, a sixth lens group G6 and a seventh lens group G7, all of which are movable along the optical axis direction; at least one of the third lens group G3, the fourth lens group G4, the fifth lens group G5, the sixth lens group G6 and the seventh lens group G7 is moved so as to obtain pictures of different sizes without changing the projection distance;

[0041] The fixed group includes at least one meniscus-type positive power lens;

[0042] Among them, the aperture S is located in any lens group in the zoom group, so that when the lens group in the zoom group moves, the angle of the light passing through the aperture S is controlled, the change of the F Number of the entire system before and after the movement is reduced, and the purpose of reducing the change of the projection picture brightness during the zoom process is achieved.

[0043] The large-magnification continuous zoom projection optical system provided in the embodiment of the present application comprises at least two movable lens groups in the focus group. By moving the at least two lens groups, a clear picture can be obtained at different projection distances. The zoom group comprises at least five movable zoom lens groups. The function of this lens group is to obtain pictures of different sizes without changing the projection distance by moving the at least five lens groups. In addition, the diaphragm is located in one of the lens groups (the diaphragm is arranged in the sixth lens group G6 in the figure). The function of this lens group is to control the angle of the light passing through the diaphragm when the at least five lens groups are moved, thereby reducing the change in the F Number (focal length value and aperture number are used to express the relationship between the focal length (mm) and the aperture diameter (mm) of the lens) of the entire system before and after the movement, thereby reducing the change in the brightness of the projection picture during the zooming process. The adjustment process is as follows: Figure 2 shown.

[0044] In a specific implementation, in order to realize the functions of each group, the embodiment of the present application can provide that the first lens group G1 has a positive focal power, and the second lens group G2 has a negative focal power; the focal length f1 of the first lens group G1 and the focal length f2 of the second lens group G2 satisfy the following relationship: -0.4 <f2 / f1<-0.1。

[0045] Furthermore, the first lens group G1 includes a first lens L1 and a second lens L2; ​​the first lens L1 is a biconvex positive power lens, and the second lens L2 is a meniscus negative power lens;

[0046] The second lens group G2 includes a third lens L3, a fourth lens L4, a fifth lens L5 and a sixth lens L6; the third lens L3 is a meniscus type negative power lens, the fourth lens L4 is a biconcave type negative power lens, the fifth lens L5 is a biconcave type negative power lens, and the sixth lens L6 is a meniscus type positive power lens.

[0047] The minimum focal length fw obtained by moving at least five lens groups of the zoom group and the maximum focal length ft obtained by moving at least five lens groups of the zoom group satisfy the following relationship: 1.8 <ft / fw<2.2。

[0048] The maximum aperture F#w obtained by moving at least five lens groups of the zoom group and the minimum aperture F#t obtained by moving at least five lens groups of the zoom group satisfy the following relationship: <F#w / F#t<1.15。

[0049] The minimum focal length fw obtained by moving at least five lens groups of the zoom group and the total length TTL of the entire optical system satisfy the following relationship: 0.08 <fw / TTL<0.12。

[0050] The maximum field of view FOV obtained by moving at least five lens groups of the zoom group satisfies the following relationship: 40° <FOV<60°。

[0051] The back focus FBL of the optical system and the total length TTL of the entire optical projection system satisfy the following relationship: 0.2 <FBL / TTL<0.3。

[0052] The third lens group G3 includes a seventh lens L7; the seventh lens L7 is a biconvex positive power lens;

[0053] The fourth lens group G4 includes an eighth lens L8; the eighth lens L8 is a meniscus type positive power lens;

[0054] The fifth lens group G5 includes a ninth lens L9; the ninth lens L9 is a biconcave lens with negative optical power;

[0055] The sixth lens group G6 includes a tenth lens L10 and an eleventh lens L11; the tenth lens L10 with a biconcave negative focal power and the eleventh lens L11 with a biconvex positive focal power form a cemented lens;

[0056] The seventh lens group G7 includes a twelfth lens L12, a thirteenth lens L13, a fourteenth lens L14, a fifteenth lens L15 and a sixteenth lens L16; the twelfth lens L12 of meniscus type negative optical focal power, the thirteenth lens L13 of biconvex type positive optical focal power and the fourteenth lens L14 of meniscus type negative optical focal power form a triplet lens, the fifteenth lens L15 is a biconvex type positive optical focal power lens, and the sixteenth lens L16 is a meniscus type positive optical focal power lens.

[0057] The fixed lens group includes an eighth lens group G8, and the eighth lens group G8 includes a seventeenth lens L17; the seventeenth lens L17 is a meniscus-type positive power lens.

[0058] The system provided in the embodiments of the present application is described in detail below.

[0059] The system is composed of a focus group, a zoom group and a fixed group from the object side to the image side. The focus group includes the first lens group G1 to the second lens group G2, and the two lens groups are movable. The zoom group includes the third lens group G3 to the seventh lens group G7, and the five lens groups are movable. The fixed group includes the eighth lens group G8.

[0060] The first lens group G1 includes a first lens L1 and a second lens L2, wherein the first lens L1 is a biconvex positive power lens, and the second lens L2 is a meniscus negative power lens.

[0061] The second lens group G2 includes a third lens L3 to a sixth lens L6, wherein the third lens L3 is a meniscus type negative power lens, the fourth lens L4 is a biconcave type negative power lens, the fifth lens L5 is a biconcave type negative power lens, and the sixth lens L6 is a meniscus type positive power lens.

[0062] The third lens group G3 includes a seventh lens L7, wherein the seventh lens L7 is a biconvex positive power lens.

[0063] The fourth lens group G4 includes an eighth lens L8, wherein the eighth lens L8 is a meniscus type positive power lens.

[0064] The fifth lens group G5 includes a ninth lens L9, wherein the ninth lens L9 is a biconcave lens with negative refractive power.

[0065] The sixth lens group G6 includes a tenth lens L10 and an eleventh lens L11, wherein the biconcave negative-power tenth lens L10 and the biconvex positive-power eleventh lens L11 form a cemented lens. A stop S may be located in the sixth lens group G6.

[0066] The seventh lens group G7 includes twelfth lens L12 to sixteenth lens L16, wherein the twelfth lens L12 of meniscus type with negative optical power, the thirteenth lens L13 of biconvex type with positive optical power and the fourteenth lens L14 of meniscus type with negative optical power form a triplet lens, the fifteenth lens L15 is a biconvex type with positive optical power lens, and the sixteenth lens L16 is a meniscus type with positive optical power lens.

[0067] The eighth lens group G8 includes a seventeenth lens L17, wherein the seventeenth lens L17 is a meniscus type positive power lens.

[0068] Verification results are as follows Figure 3 , Figure 4 , Figure 5 , Figure 6The system provided in the embodiment of the present application can obtain a 2x continuous zoom system by moving the five lens groups of the zoom group, with the minimum focal length being 24mm (the corresponding maximum field of view angle is 53°) and the maximum focal length being 48mm (the corresponding maximum field of view angle is 28°).

[0069] The optical data are shown in Table 1.

[0070] Table 1

[0071]

[0072]

[0073] Wherein, R represents the radius of curvature of the lens, d represents the lens thickness or air space, nd represents the refractive index of the glass, and vd represents the Abbe number of the glass. The data of the air spaces D0 to D5 are shown in Table 2.

[0074] Table 2

[0075]

[0076]

[0077] Table 2 shows the change in air spacing between zoom groups at different focal lengths, achieving a 2x zoom.

[0078] In summary, the large-magnification continuous zoom projection optical system provided by the present application can obtain a clear picture at different projection distances by moving at least two lens groups of the focusing group. By moving at least five lens groups of the zoom group, pictures of different sizes can be obtained without changing the projection distance. The diaphragm is located in one of the lens groups of the zoom group. When the at least five lens groups of the zoom group move, the angle of the light passing through the diaphragm is controlled to reduce the change in the F Number of the entire system before and after the movement, thereby reducing the change in the brightness of the projection picture during the zooming process. Through the mutual cooperation of the lens groups, a large-magnification continuous zoom can be achieved while achieving high imaging quality, small picture distortion and clear resolution.

[0079] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0080] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A high-magnification continuous zoom projection optical system, characterized in that: Along the optical axis direction from the object side to the image side, it includes a focus group, a zoom group and a fixed group; The focus adjustment group at least includes a first lens group and a second lens group, both of which are movable along the optical axis, and at least one of the first lens group and the second lens group is moved so as to obtain a clear picture at different projection distances; The zoom group at least includes a third lens group, a fourth lens group, a fifth lens group, a sixth lens group and a seventh lens group, all of which are movable along the optical axis; Moving at least one of the third lens group, the fourth lens group, the fifth lens group, the sixth lens group, and the seventh lens group so as to obtain pictures of different sizes without changing the projection distance; The fixed group includes at least one meniscus-type positive power lens; Among them, the aperture is located in any lens group in the zoom group, so that when the lens group in the zoom group moves, the angle of the light passing through the aperture is controlled, the change of the F Number of the entire system before and after the movement is reduced, and the purpose of reducing the change of the projection picture brightness during the zoom process is achieved.

2. The high-magnification continuous zoom projection optical system according to claim 1, characterized in that: The first lens group has positive focal power, and the second lens group has negative focal power; the focal length f1 of the first lens group and the focal length f2 of the second lens group satisfy the following relationship: -0.4 <f2 / f1<-0.1。 3. The high-magnification continuous zoom projection optical system according to claim 2, characterized in that: The first lens group includes a first lens and a second lens; the first lens is a biconvex positive power lens, and the second lens is a meniscus negative power lens; The second lens group includes a third lens, a fourth lens, a fifth lens and a sixth lens; the third lens is a meniscus type negative power lens, the fourth lens is a biconcave type negative power lens, the fifth lens is a biconcave type negative power lens, and the sixth lens is a meniscus type positive power lens.

4. The high-magnification continuous zoom projection optical system according to claim 1, characterized in that: The minimum focal length fw obtained by moving at least five lens groups of the zoom group and the maximum focal length ft obtained by moving at least five lens groups of the zoom group satisfy the following relationship: 1.8 <ft / fw<2.2。 5. The high-magnification continuous zoom projection optical system according to claim 1, characterized in that: The maximum aperture F#w obtained by moving at least five lens groups of the zoom group and the minimum aperture F#t obtained by moving at least five lens groups of the zoom group satisfy the following relationship: <F#w / F#t<1.15。 6. The high-magnification continuous zoom projection optical system according to claim 1, characterized in that: The minimum focal length fw obtained by moving at least five lens groups of the zoom group and the total length TTL of the entire optical system satisfy the following relationship: 0.08 <fw / TTL<0.12。 7. The high-magnification continuous zoom projection optical system according to claim 1, characterized in that: The maximum field of view FOV obtained by moving at least five lens groups of the zoom group satisfies the following relationship: 40° <FOV<60°。 8. The high-magnification continuous zoom projection optical system according to claim 1, characterized in that: The back focus FBL of the optical system and the total length TTL of the entire optical projection system satisfy the following relationship: 0.2 <FBL / TTL<0.3。 9. The high-magnification continuous zoom projection optical system according to claim 1, characterized in that: The third lens group includes a seventh lens; the seventh lens is a biconvex positive power lens; The fourth lens group includes an eighth lens; the eighth lens is a meniscus-type positive power lens; The fifth lens group includes a ninth lens; the ninth lens is a biconcave lens with negative optical power; The sixth lens group includes a tenth lens and an eleventh lens; the tenth lens with a biconcave negative focal power and the eleventh lens with a biconvex positive focal power form a cemented lens; The seventh lens group includes a twelfth lens, a thirteenth lens, a fourteenth lens, a fifteenth lens and a sixteenth lens; the twelfth lens of meniscus type negative focal power, the thirteenth lens of biconvex type positive focal power and the fourteenth lens of meniscus type negative focal power form a triple cemented lens, the fifteenth lens is a biconvex type positive focal power lens, and the sixteenth lens is a meniscus type positive focal power lens.

10. The high-magnification continuous zoom projection optical system according to claim 1, characterized in that: The fixed group includes an eighth lens group, and the eighth lens group includes a seventeenth lens; the seventeenth lens is a meniscus-type positive power lens.

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