Projection zoom lens

Abstract

The invention relates to a projection zoom lens, which comprises a first fixed group, a zoom group, a second fixed group and a focusing group which are sequentially arranged along an optical axis direction, the first fixed group comprises a first lens, a second lens and a third lens, the zoom group comprises a fourth lens, a fifth lens and a sixth lens, and the focusing group comprises a fourth lens, a fifth lens and a sixth lens. The second fixed group comprises a seventh lens, an eighth lens, a ninth lens, a tenth lens and an eleventh lens, the focusing group comprises a twelfth lens, a thirteenth lens and a fourteenth lens, the first lens to the fourteenth lens are sequentially arranged in the optical axis direction, and the zooming group and the focusing group can move in the optical axis direction for focusing; the wide-angle end and the long-focal-length end of the wide-angle long-focal-length lens are combined, the focal length ranges of the wide-angle end and the long-focal-length end are reasonably set, pictures are kept clear in large-range zooming and focusing, and the wide-angle long-focal-length lens has the advantages of being small in number of moving groups, invariable in total length, simple in zooming, small in size, low in cost, free of defocusing under the environment condition of large temperature difference, stable in working performance, high in projection quality and wide in application range.

Description

Technical Field

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

[0002] Projection has the characteristics of large screen and wide application range, which makes projection occupy an increasingly larger proportion in the display field, such as being widely used in education, home and other fields. With the rapid development of the projection market, the usability of projection has been greatly improved. The lens, as the core component of the projector, determines the variable range of the screen size.

[0003] However, the projection distance and image size of commonly used projections are greatly limited and cannot be used in a variety of scenarios. To meet different needs, it is often necessary to develop multiple fixed-focus projection lenses, which cannot balance cost and ease of use; or use a projector with a zoom function to meet the needs of different projection venues. The lens of such a projector with a zoom function usually includes multiple lens groups. The effective focal length of the lens is changed by changing the relative position between the lens groups, thereby achieving the zoom function. However, the existing zoom projection lenses are generally large in size, which will cause the overall size of the projector to be relatively large. At the same time, the optical parameter design of each lens group of the existing lens often has the following defects: (1) It cannot effectively correct aberrations and distortions, which is not conducive to improving image quality; (2) It can only achieve a small zoom ratio (such as 1x-2x), with an F number of 1.7-2.0, which cannot meet the high-end projection needs of commercial and home scenes.

[0004] Therefore, a zoom projection solution is proposed, which can meet the automatic adjustment of different frames and projection distances and high-quality projection effects. Summary of the invention

[0005] The purpose of the present invention is to address the above problems and propose a projection zoom lens, which has a small size, a large aperture, an adjustable projection distance and a projection ratio, and the total length of the zoom process remains unchanged. It can provide sufficient projection brightness and size, and the projection picture is clear and sharp, with high contrast and accurate color reproduction. At the same time, it is not sensitive to temperature, has a simple zoom form, and is easy to mass produce.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] The present invention provides a projection zoom lens, comprising a first fixed group, a zoom group, a second fixed group and a focus group, which are arranged in sequence along an optical axis direction, wherein the first fixed group comprises a first lens with negative optical power, a second lens with positive optical power and a third lens with positive optical power, the first lens and the second lens form a first cemented lens group, the zoom group comprises a fourth lens with negative optical power, a fifth lens with negative optical power and a sixth lens with positive optical power, the fifth lens and the sixth lens form a second cemented lens group, the second fixed group comprises a fourth lens with negative optical power, a fifth lens with negative optical power and a sixth lens with positive optical power, the fifth lens and the sixth lens form a second cemented lens group, the second fixed group comprises a fourth lens with positive optical power, a fifth lens with negative optical power and a sixth lens with positive optical power, the fifth lens and the sixth lens form a second cemented lens group, the The optical system comprises a seventh lens having a focal power, an eighth lens having a negative focal power, a ninth lens having a positive focal power, a tenth lens having a negative focal power and an eleventh lens having a positive focal power, the ninth lens and the tenth lens form a third cemented lens group, the focusing group comprises a twelfth lens having a positive focal power, a thirteenth lens having a positive focal power and a fourteenth lens having a negative focal power, the thirteenth lens and the fourteenth lens form a fourth cemented lens group, the first lens to the fourteenth lens are arranged in sequence along the optical axis direction, and the zoom group and the focusing group can move along the optical axis direction for focusing;

[0008] The projection zoom lens also meets the following conditions:

[0009] 14mm≤fw≤16mm,42mm≤ft≤46mm;

[0010] Wherein, fw is the focal length of the projection zoom lens at the wide-angle end, and ft is the focal length of the projection zoom lens at the telephoto end.

[0011] Preferably, the projection zoom lens also meets the following conditions:

[0012]

[0013] Among them, EFL1 is the combined focal length of the first fixed group, EFL3 is the combined focal length of the second fixed group, EFL2 is the combined focal length of the zoom group, and EFL4 is the combined focal length of the focus group.

[0014] Preferably, the projection zoom lens also meets the following conditions:

[0015]

[0016] Wherein, thi12w is the on-axis gap between the first fixed group and the zoom group at the wide-angle end, ttl is the distance from the first lens to the image plane, and thi23t is the on-axis distance between the zoom group and the second fixed group at the telephoto end.

[0017] Preferably, the projection zoom lens also meets the following conditions:

[0018] 95mm≤ttl≤130mm

[0019] Wherein, thi34w is the axial gap between the second fixed group and the focusing group at the wide-angle end, and ttl is the distance from the first lens to the image plane.

[0020] Preferably, the projection zoom lens also meets the following conditions:

[0021]

[0022] Wherein, dwt is the moving distance of the zoom group from the wide-angle end to the telephoto end, and ttl is the distance from the first lens to the image plane.

[0023] Preferably, the projection zoom lens also meets the following conditions:

[0024]

[0025] Wherein, EPDt is the entrance pupil diameter at the telephoto end of the projection zoom lens.

[0026] Preferably, the projection zoom lens also meets the following conditions:

[0027] -1°≤CRAw≤1°, -1.5°≤CRAt≤1.5°

[0028] Wherein, CRAw is the angle between the principal ray of the maximum imaging circle at the wide-angle end of the projection zoom lens and the image plane, and CRAt is the angle between the principal ray of the maximum imaging circle at the telephoto end of the projection zoom lens and the image plane.

[0029] Preferably, the projection zoom lens also meets the following conditions:

[0030]

[0031] Wherein, ind7 is the refractive index of the seventh lens at a wavelength of 550 nm, ind12 is the refractive index of the twelfth lens at a wavelength of 550 nm, thi7 is the median thickness of the seventh lens, and thi12 is the median thickness of the twelfth lens.

[0032] Preferably, the projection zoom lens also meets the following conditions:

[0033]

[0034] Wherein, SD1 is the effective semi-aperture of the first lens, and SD12 is the effective semi-aperture of the twelfth lens.

[0035] Preferably, the projection zoom lens further includes a diaphragm, which is located between the sixth lens and the seventh lens and fixed to the second fixed group.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] The lens includes a first fixed group, a zoom group, a second fixed group and a focus group arranged in sequence along the optical axis. The zoom group and the focus group are moved to focus. The lens has a small size, low cost, a large aperture, an adjustable projection distance and projection ratio, and the total length of the zoom process remains unchanged. It can provide sufficient projection brightness and size, and the projection picture is clear and sharp, with high contrast and accurate color reproduction. It is not sensitive to temperature, has a simple zoom form, and is easy to mass produce. Zooming is simple and fast. Specifically, it adopts a 14-lens structure with a small size, which reduces costs while ensuring image quality. The lens structure is compact by reasonably distributing the optical focal length, and the total length of the lens is within 130mm. The reasonable distribution of lenses corrects various aberrations and improves edge image quality, thereby improving image quality. The maximum aperture can reach F1.6, which enables the lens to have a higher light output capacity. At the same time, the lens materials are reasonably set to complement each other so that the lens does not defocus under environmental conditions of -20℃ to +70℃, and the working performance is more stable. It can be adapted to 0.33" DMD chip, with high pixels and better image quality, so that the picture remains clear during zooming and focusing in a large range, with high projection quality and a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a schematic structural diagram of the wide-angle end of the projection zoom lens of Embodiment 1 of the present invention;

[0039] Figure 2 This is a schematic structural diagram of the telephoto end of a projection zoom lens according to Embodiment 1 of the present invention;

[0040] Figure 3 The longitudinal spherical aberration diagram, astigmatism diagram and distortion diagram of the wide-angle end of the projection zoom lens of Example 1 of the present invention are shown;

[0041] Figure 4 The longitudinal spherical aberration diagram, astigmatism diagram and distortion diagram of the projection zoom lens at the telephoto end of Example 1 of the present invention;

[0042] Figure 5 This is a schematic diagram of the structure of the wide-angle end of the projection zoom lens according to Embodiment 2 of the present invention;

[0043] Figure 6 This is a schematic structural diagram of the telephoto end of a projection zoom lens according to Embodiment 2 of the present invention;

[0044] Figure 7 The longitudinal spherical aberration diagram, astigmatism diagram and distortion diagram of the wide-angle end of the projection zoom lens according to Embodiment 2 of the present invention;

[0045] Figure 8 The longitudinal spherical aberration diagram, astigmatism diagram and distortion diagram of the projection zoom lens at the telephoto end of Example 2 of the present invention;

[0046] Fig. 9 This is a schematic diagram of the structure of the wide-angle end of the projection zoom lens according to Embodiment 3 of the present invention;

[0047] Fig.10 This is a schematic structural diagram of the telephoto end of a projection zoom lens according to Embodiment 3 of the present invention;

[0048] Fig.11 The longitudinal spherical aberration diagram, astigmatism diagram and distortion diagram of the wide-angle end of the projection zoom lens of Example 3 of the present invention are shown;

[0049] Fig.12 The longitudinal spherical aberration diagram, astigmatism diagram and distortion diagram of the projection zoom lens at the telephoto end of Example 3 of the present invention;

[0050] Fig.13 This is a schematic structural diagram of the wide-angle end of a projection zoom lens according to Embodiment 4 of the present invention;

[0051] Fig.14 This is a schematic structural diagram of the telephoto end of a projection zoom lens according to Embodiment 4 of the present invention;

[0052] Fig.15 The longitudinal spherical aberration diagram, astigmatism diagram and distortion diagram of the wide-angle end of the projection zoom lens of Example 4 of the present invention;

[0053] Fig.16 Graphs showing longitudinal spherical aberration, astigmatism and distortion at the telephoto end of the projection zoom lens according to Embodiment 4 of the present invention.

[0054] Explanation of the accompanying reference numerals: G1, first fixed group; G2, zoom group; G3, second fixed group; G4, focus group; G5, galvanometer; G6, prism; STO, aperture; CG, protection glass; IMA, image plane; L1, first lens; L2, second lens; L3, third lens; L4, fourth lens; L5, fifth lens; L6, sixth lens; L7, seventh lens; L8, eighth lens; L9, ninth lens; L10, tenth lens; L11, eleventh lens; L12, twelfth lens; L13, thirteenth lens; L14, fourteenth lens. DETAILED DESCRIPTION

[0055] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0056] It should be noted that, unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0057] A projection zoom lens, comprising a first fixed group G1, a zoom group G2, a second fixed group G3 and a focus group G4, which are sequentially arranged along an optical axis direction, wherein the first fixed group G1 comprises a first lens L1 having a negative optical power, a second lens L2 having a positive optical power and a third lens L3 having a positive optical power, the first lens L1 and the second lens L2 form a first cemented lens group, the zoom group G2 comprises a fourth lens L4 having a negative optical power, a fifth lens L5 having a negative optical power and a sixth lens L6 having a positive optical power, the fifth lens L5 and the sixth lens L6 form a second cemented lens group, and the second fixed group G3 comprises a seventh lens having a positive optical power L7, an eighth lens L8 with negative power, a ninth lens L9 with positive power, a tenth lens L10 with negative power and an eleventh lens L11 with positive power, the ninth lens L9 and the tenth lens L10 form a third cemented lens group, the focusing group G4 includes a twelfth lens L12 with positive power, a thirteenth lens L13 with positive power and a fourteenth lens L14 with negative power, the thirteenth lens L13 and the fourteenth lens L14 form a fourth cemented lens group, the first lens L1 to the fourteenth lens L14 are arranged in sequence along the optical axis, and the zoom group G2 and the focusing group G4 can move along the optical axis to adjust the focus;

[0058] The projection zoom lens also meets the following conditions:

[0059] 14mm≤fw≤16mm,42mm≤ft≤46mm;

[0060] Wherein, fw is the focal length of the projection zoom lens at the wide-angle end, and ft is the focal length of the projection zoom lens at the telephoto end.

[0061] The projection zoom lens comprises a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10, an eleventh lens L11, a twelfth lens L12, a thirteenth lens L13, and a fourteenth lens L14, which are arranged in sequence along the optical axis, and preferably adopt an all-glass structure, that is, fourteen glass lenses are used.

[0062] Among them, the first fixed group G1 is composed of a first lens L1 with negative optical power, a second lens L2 with positive optical power, and a third lens L3 with positive optical power. The first lens L1 and the second lens L2 form a first cemented lens group. The first cemented lens group can provide good chromatic aberration correction capability, so that both the telephoto end and the wide-angle end have better chromatic aberration performance. At the same time, the surface is flat, which can reduce the introduction of spherical aberration at both the wide-angle end and the telephoto end, making it easier to expand the aperture. The third lens L3 shares the optical power of the second lens L2, avoids excessive surface curvature, and helps improve processability.

[0063] The zoom group G2 is composed of a fourth lens L4 with negative power, a fifth lens L5 with negative power, and a sixth lens L6 with positive power. The fifth lens L5 and the sixth lens L6 form a second cemented lens group. The fourth lens L4 helps to quickly shrink the light, reduce the light height, and improve the distortion and field curvature correction capabilities. It is preferred that the fourth lens L4 is a glass aspherical lens, which can further improve the system integration and resolution. The second cemented lens group can provide appropriate chromatic aberration and spherical aberration correction for the full focal length during movement, and the zoom group G2 has a negative power, which helps to shorten the movement stroke and reduce the total length of the lens.

[0064] The second fixed group G3 includes a seventh lens L7 with positive power, an eighth lens L8 with negative power, a ninth lens L9 with positive power, a tenth lens L10 with negative power and an eleventh lens L11 with positive power. The ninth lens L9 and the tenth lens L10 form a third cemented lens group. The seventh lens L7 has a larger refractive index, which reduces the surface curvature and is more conducive to processing. The smaller thickness can avoid the problem of low short-wave transmittance of high-refractive index materials. The seventh lens L7 and the eighth lens L8 use a combination of positive and negative power to form a light height difference, provide field curvature compensation, and help improve the concentration of MTF. In the third cemented lens group, the ninth lens L9 has a high Abbe number, the tenth lens L10 has a low Abbe number, and the combined lens can provide sufficient chromatic aberration compensation, and negative dndt materials can be used to compensate for high and low temperatures. The eleventh lens L11 can share the larger spherical aberration at the rear end and reduce the tolerance sensitivity. It is preferred that the eleventh lens L11 is a glass aspherical lens, which can effectively reduce the surface curvature and improve the processability.

[0065] The focusing group G4 includes a twelfth lens L12 with positive power, a thirteenth lens L13 with positive power and a fourteenth lens L14 with negative power. The thirteenth lens L13 and the fourteenth lens L14 form a fourth cemented lens group. The eleventh lens L11, the twelfth lens L12 and the thirteenth lens L13 are three positive lenses, which jointly share the spherical aberration of the rear group (focusing group G4), reduce the sensitivity of spherical aberration, and help improve the production yield. The fourth cemented lens group has a flat surface, which helps to reduce spherical aberration and correct the incident angle of the main light.

[0066] And by reasonably setting the focal length fw at the wide-angle end and the focal length ft at the telephoto end of the projection zoom lens, in a specific embodiment, fw and ft can take any value within a range, such as fw can be: 14.5, 15.16, 15.3, 15.6, in mm; ft can be: 42.6, 43.3, 44.2, 44.6, in mm. If the above conditional formula is met, the lens has a certain zoom capability, and the projection ratio at the wide-angle end is around 2.0, and the projection ratio at the telephoto end is around 6.0, which meets the 3x zoom range required by customers, and the projection ratio variation range is large; if it exceeds this range, the zoom ratio of the lens is too large or too small, which does not meet the requirements of miniaturization and large zoom, and is difficult to implement and has poor mass production.

[0067] The zoom group G2 of the projection zoom lens moves smoothly from the wide-angle end to the telephoto end without an inflection point; the focus group G4 is responsible for maintaining clear imaging during the zoom process and object distance adjustment process, and has a short moving stroke, which is conducive to fast focusing. Temperature compensation is achieved through the materials and optical focal lengths of the second lens L2, the fifth lens L5, the ninth lens L9, the eleventh lens L11, and the thirteenth lens L13, which are insensitive to temperature and have good working stability.

[0068] In one embodiment, the projection zoom lens further satisfies the following conditions:

[0069]

[0070] Among them, EFL1 is the combined focal length of the first fixed group G1, EFL3 is the combined focal length of the second fixed group G3, EFL2 is the combined focal length of the zoom group G2, and EFL4 is the combined focal length of the focus group G4.

[0071] Specifically, EFL1 / EFL3 can take any value within the range, such as 0.87, 0.92, 1.21, and 1.1. If the above conditional formula is met, the first fixed group G1 and the second fixed group G3 can reasonably distribute the optical power, evenly distribute the aberration from wide angle to telephoto, ensure that no serious optical power aggregation occurs inside the fixed group, and avoid excessive concentration of tolerances; if this range is exceeded, aberrations are easily over-concentrated in the first fixed group G1 or the second fixed group G2, resulting in high tolerance sensitivity of a single group and reducing the overall mass production of the lens. EFL2 / EFL4 can take any value within the range, such as -0.52, -0.51, -0.49, and 0.47. When the above conditional formula is met, the zoom group G2 and the focus group G4 can obtain a more balanced optical power, and the optical power of the zoom group G2 is small, so that the aberration change during the movement is small, and the internal tolerance sensitivity is low. When assembled with the lens barrel and the cam, the coaxiality tolerance can also be well guaranteed to meet the actual needs. The cam is a prior art structure well known to those skilled in the art, which is used to drive the zoom group G2 to move and zoom, and will not be described in detail here; it can further improve the movement stroke of the zoom group G2 and the focus group G4, and improve the overall compactness. Beyond this range, the zoom group G2 bears too much or too little optical power, and does not have good characteristics in terms of movement stroke and tolerance.

[0072] In one embodiment, the projection zoom lens further satisfies the following conditions:

[0073]

[0074] Wherein, thi12w is the axial gap between the first fixed group G1 and the zoom group G2 at the wide-angle end, ttl is the distance from the first lens L1 to the image plane IMA, and thi23t is the axial distance between the zoom group G2 and the second fixed group G3 at the telephoto end.

[0075] Specifically, thi12w / ttl can take any value within the range, such as 0.005, 0.0053, 0.0068, 0.008. When the above conditional formula is met, there is a reasonable air gap between the first fixed group G1 and the zoom group G2, which avoids lens collision during movement, makes full use of the internal space, compresses the stroke, and ensures the small volume of the entire lens; exceeding this range, the distance between the first fixed group G1 and the zoom group G2 is too small or too large, which is not conducive to the miniaturization design of the lens, and there is a risk of collision. thi23t / ttl can take any value within the range, such as 0.015, 0.013, 0.017, 0.018. When the above conditional formula is met, there is a suitable gap between the zoom group G2 and the second fixed group G2, which is convenient for arranging the aperture and avoiding collision; exceeding this range, the gap is too large or too small, which is not conducive to the miniaturization design of the lens.

[0076] In one embodiment, the projection zoom lens further satisfies the following conditions:

[0077] 95mm≤ttl≤130mm

[0078] Wherein, thi34w is the axial gap between the second fixed group G3 and the focusing group G4 at the wide-angle end, and ttl is the distance from the first lens L1 to the image plane IMA.

[0079] Specifically, thi34w / ttl can take any value within the range, such as 0.008, 0.01, 0.02, 0.05. If the above conditional formula is met, there is a reasonable gap between the second fixed group G2 and the focus group G4, which can cover the focus margin of the full focal length and frame adjustment, and ensure that there is no interference during the focusing process. ttl can take any value within the range, such as 122, 116, 107, 101, unit mm. If the above conditional formula is met, the large zoom projection system has a good miniaturized design, and the compactness can be further improved by reasonably designing the surface shape of the lens (such as using an aspherical surface), thereby increasing the convenience of user use. Exceeding this range, there is a risk of expansion between the second fixed group G2 and the focus group G4, and the total length is too large or too small, which does not meet the miniaturization requirements.

[0080] In one embodiment, the projection zoom lens further satisfies the following conditions:

[0081]

[0082] Wherein, dwt is the moving distance of the zoom group G2 from the wide-angle end to the telephoto end, and ttl is the distance from the first lens L1 to the image plane IMA.

[0083] Specifically, dwt / ttl can take any value within the range, such as 0.13, 0.15, 0.16, and 0.18. If the above conditional formula is met, the zoom group G2 has a reasonable moving stroke, and there is no inflection point during the movement, which is convenient for the design and processing of the cam; and a reasonably small stroke helps the lens to further achieve miniaturization and improve compactness. If the upper limit is exceeded, the moving stroke of the zoom group G2 is too large, which is not conducive to the miniaturization of the lens; if the lower limit is exceeded, the stroke of the zoom group G2 is too small, which is easy to concentrate the optical focal length and bring about a stroke inflection point, which is not conducive to the realization of the cam.

[0084] In one embodiment, the projection zoom lens further satisfies the following conditions:

[0085]

[0086] Wherein, EPDt is the entrance pupil diameter at the telephoto end of the projection zoom lens.

[0087] Specifically, ft / EPDt can take any value within the range, such as 1.62, 1.64, 1.7, 1.8. It is convenient to set the aperture STO between the zoom group G2 and the second fixed group G2, and fix it to the second fixed group G2, which is beneficial for the wide-angle end and the telephoto end to enjoy the same aperture value during the entire zoom process, and can make full use of the projected light intensity. If the above conditions are met, the lens has a larger aperture and a higher light clearance, which is beneficial to the optical and mechanical lighting of the projector, and can provide sufficient brightness to directly improve the observation experience. Exceeding the specified range, the aperture number is too large, which introduces more spherical aberration and requires more lenses to compensate, which weakens the miniaturization feature and increases the cost.

[0088] In one embodiment, the projection zoom lens further satisfies the following conditions:

[0089] -1°≤CRAw≤1°, -1.5°≤CRAt≤1.5°

[0090] Wherein, CRAw is the angle between the principal ray of the maximum imaging circle at the wide-angle end of the projection zoom lens and the image plane IMA, and CRAt is the angle between the principal ray of the maximum imaging circle at the telephoto end of the projection zoom lens and the image plane IMA.

[0091] Specifically, CRAw can take any value within the range, such as -0.35°, -0.8°, 0.6°, -0.9°; CRAt can take any value within the range, such as -1.2°, -0.7°, 0.6°, -0.1°. When the above conditional formula is met, the telecentricity of the lens is controlled within a very small range, ensuring that the lens is aligned with the light output direction, improving the light output efficiency from the center to the edge of the picture, and avoiding uneven brightness; at the same time, the difference between the wide-angle end and the telephoto end is small, and the picture consistency is good during zooming; beyond this range, the telecentricity is too large, which is easy to cause low light output efficiency and affect the brightness and uniformity of the picture.

[0092] In one embodiment, the projection zoom lens further satisfies the following conditions:

[0093]

[0094] Wherein, ind7 is the refractive index of the seventh lens L7 at a wavelength of 550 nm, ind12 is the refractive index of the twelfth lens L12 at a wavelength of 550 nm, thi7 is the median thickness of the seventh lens L7, and thi12 is the median thickness of the twelfth lens L12.

[0095] Specifically, (ind7+ind12) / (thi7+thi12) can take any value within the range, such as 0.8, 0.82, 0.86, 0.88. To meet the above expression, the seventh lens L7 and the twelfth lens L12 can reasonably select high refractive index materials and ensure that the thickness is thin, so as to minimize the impact of high refractive index materials on short-wave blue light. In combination with the multi-layer coating process, the transmittance of RGB can be balanced to avoid color temperature drift. Beyond this range, the lens material selection is inappropriate, and the thickness is too large or too small, which is not conducive to processing and transmittance, affecting the user experience.

[0096] In one embodiment, the projection zoom lens further satisfies the following conditions:

[0097]

[0098] Wherein, SD1 is the effective semi-aperture of the first lens L1, and SD12 is the effective semi-aperture of the twelfth lens L12.

[0099] Specifically, SD1 / SD12 can take any value within the range, such as 1.72, 1.77, 1.92, and 1.96. The first lens L1 is the largest diameter of the lens, and the twelfth lens L12 is the largest diameter of the focus group G4 lens. The above conditional formula is met, and the aperture of the first lens L1 is not much different from the aperture of the twelfth lens L12. By superimposing the lens barrel and the cam, the diameter of the head and the tail of the structure can be basically consistent, which is conducive to the overall miniaturization design of the projection system, and also helps to reduce the exposed area of ​​the projection, improve the integration, and reduce the discomfort of exposure. If the upper limit value is exceeded, the head size is too large, which reduces the aesthetics of the application; if the lower limit value is below the lower limit value, the head size is too small, the design is difficult, and more lenses are required to compensate for the optical distortion caused by the small head, which is not conducive to cost reduction.

[0100] In one embodiment, the projection zoom lens further includes a stop STO, which is located between the sixth lens L6 and the seventh lens L7 and fixed to the second fixed group G3.

[0101] Specifically, the aperture STO is located between the sixth lens L6 and the seventh lens L7, and is fixed to the second fixed group G2, and does not move during the entire zooming process, forming an effect of a fixed aperture from wide angle to telephoto.

[0102] For ease of understanding, the following is a detailed description through specific embodiments. The reference wavelength of the effective focal length, Abbe number, and refractive index in the following optical parameters is 550 nm, and the other embodiments are the same.

[0103] Embodiment 1:

[0104] like Figure 1-Figure 4As shown, in this embodiment, the projection zoom lens comprises a first fixed group G1, a zoom group G2, a second fixed group G3, a focusing group G4, a galvanometer G5, a prism G6 and a protective glass CG which are sequentially arranged along the optical axis direction. The first fixed group G1 comprises a first lens L1 with negative optical power, a second lens L2 with positive optical power and a third lens L3 with positive optical power. The first lens L1 and the second lens L2 form a first cemented lens group. The zoom group G2 comprises a fourth lens L4 with negative optical power, a fifth lens L5 with negative optical power and a sixth lens L6 with positive optical power. The fifth lens L5 and The sixth lens L6 forms the second cemented lens group, the second fixed group G3 includes the seventh lens L7 with positive focal power, the eighth lens L8 with negative focal power, the ninth lens L9 with positive focal power, the tenth lens L10 with negative focal power and the eleventh lens L11 with positive focal power, the ninth lens L9 and the tenth lens L10 form the third cemented lens group, the focusing group G4 includes the twelfth lens L12 with positive focal power, the thirteenth lens L13 with positive focal power and the fourteenth lens L14 with negative focal power, and the thirteenth lens L13 and the fourteenth lens L14 form the fourth cemented lens group. All lenses are glass spherical lenses. The galvanometer G5 is used to perform high-frequency vibration in different directions, so that the image expands the pixel range on the original pixel for a short time, and uses the visual persistence effect to increase the pixel recognition of the human eye, thereby improving the projection resolution; the prism G6 is an equivalent flat plate, which is used to complete the light aggregation for different light source combinations, such as providing a suitable reflection angle and refraction angle for each light. It is a well-known technology for those in the field and will not be repeated here.

[0105] The effective focal length of this optical system is fw=15.168mm, ft=44.66mm, the aperture number Fno=1.64, and the distance ttl from the object side of the first lens L1 to the image plane IMA is 122.07mm. It can be seen that this optical system can achieve large zoom, large aperture, and miniaturized design. The photosensitive chip at the image plane IMA can use a digital micromirror device (DMD).

[0106] Specifically, the values ​​of the parameters of the lens in this embodiment are as shown in Table 1 below:

[0107] Table 1

[0108]

[0109]

[0110] See also Figure 1 and Figure 2, which respectively correspond to the structural schematic diagrams of the wide-angle end and the telephoto end of the projection zoom lens of Example 1, wherein the surface number S0 represents the object plane, the surface numbers S1 to S24 represent the mirror surfaces from the object side of the first lens L1 to the image side of the fourteenth lens L14 in sequence, the cemented surface of the cemented lens group is regarded as one surface, STO represents the aperture, and the surface numbers S25, S27, S29, and S31 represent the galvanometer G5, the prism G6, the protective glass CG, and the digital micromirror device ( The surface numbers S26, S28, S30, and S32 represent the image side of the galvanometer G5, prism G6, protective glass CG, and digital micromirror device (DMD) respectively. d1 represents the axial gap between the first fixed group G1 and the zoom group G2, d2 represents the axial gap between the zoom group G2 and the aperture STO, d3 represents the axial gap between the second fixed group G2 and the focus group G4, and d4 represents the axial gap between the focus group G4 and the galvanometer G5. The moving relationship of the zoom group G2 is shown in d1 and d2 in Table 2, and the moving relationship of the focus group G4 is shown in d3 and d4 in Table 2; the focus group G4 is responsible for the focusing effect of different frames to achieve the transformation of the projection distance from 1.5m to 7m, and supports the transformation of the projection size from 11inch to 158inch.

[0111] Table 2

[0112]

[0113]

[0114] Figure 3 This is the wide-angle end aberration diagram of this embodiment, Figure 4The aberration diagrams at the telephoto end of this embodiment include the longitudinal spherical aberration diagram (LONGITUD INAL SPHERICAL ABER.), field curvature diagram (ASTIGMATIC FIELD CURVES) and distortion diagram (DISTORTION) of the optical system. Among them, the longitudinal spherical aberration diagram represents the deviation of the convergent focus of light of different wavelengths after passing through the lens. The ordinate of the longitudinal spherical aberration diagram represents the normalized pupil coordinate (Normalized PupilCoordinator) from the center of the pupil to the edge of the pupil, and the abscissa represents the distance from the imaging surface to the intersection of the light and the optical axis (in mm). It can be seen from the longitudinal spherical aberration diagram that the degree of deviation of the convergent focus of light of each wavelength in this embodiment tends to be consistent, the diffuse spots or color halos in the imaging picture are effectively suppressed, and the difference between single wavelength and complex wavelength is small. In the field curvature diagram, the S curve represents the sagittal field curvature at a wavelength of 550nm, and the T curve represents the meridian field curvature at a wavelength of 550nm. It can be seen that the field curvature of the optical system is small, the field curvature and astigmatism of each field of view are well corrected, and the center and edge of the field of view have clear images. From the distortion diagram (DISTORTION), it can be seen that the image deformation caused by the main beam is small, and the imaging quality of the system is excellent. Therefore, the longitudinal spherical aberration, field curvature and distortion of the optical system are well controlled, so that the optical system has good imaging quality.

[0115] Embodiment 2:

[0116] like Figure 5As shown, in this embodiment, the projection zoom lens comprises a first fixed group G1, a zoom group G2, a second fixed group G3, a focusing group G4, a galvanometer G5, a prism G6 and a protective glass CG which are sequentially arranged along the optical axis direction. The first fixed group G1 comprises a first lens L1 with negative optical power, a second lens L2 with positive optical power and a third lens L3 with positive optical power. The first lens L1 and the second lens L2 form a first cemented lens group. The zoom group G2 comprises a fourth lens L4 with negative optical power, a fifth lens L5 with negative optical power and a sixth lens L6 with positive optical power. The fifth lens L5 and The sixth lens L6 forms the second cemented lens group, the second fixed group G3 includes the seventh lens L7 with positive focal power, the eighth lens L8 with negative focal power, the ninth lens L9 with positive focal power, the tenth lens L10 with negative focal power and the eleventh lens L11 with positive focal power, the ninth lens L9 and the tenth lens L10 form the third cemented lens group, the focusing group G4 includes the twelfth lens L12 with positive focal power, the thirteenth lens L13 with positive focal power and the fourteenth lens L14 with negative focal power, and the thirteenth lens L13 and the fourteenth lens L14 form the fourth cemented lens group. All lenses are glass spherical lenses. The galvanometer G5 is used to perform high-frequency vibration in different directions, so that the image expands the pixel range on the original pixel for a short time, and uses the visual persistence effect to increase the pixel recognition of the human eye, thereby improving the projection resolution; the prism G6 is an equivalent flat plate, which is used to complete the light aggregation for different light source combinations, such as providing a suitable reflection angle and refraction angle for each light. It is a well-known technology for those in the field and will not be repeated here.

[0117] The effective focal length of this optical system is fw=15.158mm, ft=44.53mm, the aperture number Fno=1.63, and the distance ttl from the object side of the first lens L1 to the image plane IMA is 119.34mm. It can be seen that this optical system can achieve large zoom, large aperture, and miniaturized design. The photosensitive chip at the image plane IMA can use a digital micromirror device (DMD).

[0118] Specifically, the values ​​of the parameters of the lens in this embodiment are as shown in Table 3 below:

[0119] Table 3

[0120]

[0121]

[0122] See also Figure 5 and Figure 6, which respectively correspond to the structural schematic diagrams of the wide-angle end and the telephoto end of the projection zoom lens of Example 2, wherein the surface number S0 represents the object plane, the surface numbers S1 to S24 represent the mirror surfaces from the object side of the first lens L1 to the image side of the fourteenth lens L14 in sequence, the cemented surface of the cemented lens group is regarded as one surface, STO represents the aperture, and the surface numbers S25, S27, S29, and S31 represent the galvanometer G5, the prism G6, the protective glass CG, and the digital micromirror device ( The surface numbers S26, S28, S30, and S32 represent the image side of the galvanometer G5, prism G6, protective glass CG, and digital micromirror device (DMD) respectively. d1 represents the axial gap between the first fixed group G1 and the zoom group G2, d2 represents the axial gap between the zoom group G2 and the aperture STO, d3 represents the axial gap between the second fixed group G2 and the focus group G4, and d4 represents the axial gap between the focus group G4 and the galvanometer G5. The moving relationship of the zoom group G2 is shown in d1 and d2 in Table 4, and the moving relationship of the focus group G4 is shown in d3 and d4 in Table 4; the focus group G4 is responsible for the focusing effect of different frames to achieve the transformation of the projection distance from 1.5m to 7m, and supports the transformation of the projection size from 11inch to 158inch.

[0123] Table 4

[0124] Interval(mm) d1 d2 d3 d4 Wide-angle end 0.60 20.15 1.23 1.65 Telephoto end 18.85 1.89 2.88 0.01

[0125] Figure 7 This is the wide-angle end aberration diagram of this embodiment, Figure 8 The aberration diagrams at the telephoto end of this embodiment include the longitudinal spherical aberration diagram (LONGITUD INAL SPHERICAL ABER.), field curvature diagram (ASTIGMATIC FIELD CURVES) and distortion diagram (DISTORTION) of the optical system. Among them, the longitudinal spherical aberration diagram represents the deviation of the convergent focus of light of different wavelengths after passing through the lens. The ordinate of the longitudinal spherical aberration diagram represents the normalized pupil coordinate (Normalized PupilCoordinator) from the center of the pupil to the edge of the pupil, and the abscissa represents the distance from the imaging surface to the intersection of the light and the optical axis (in mm). It can be seen from the longitudinal spherical aberration diagram that the degree of deviation of the convergent focus of light of each wavelength in this embodiment tends to be consistent, the diffuse spots or color halos in the imaging picture are effectively suppressed, and the difference between single wavelength and complex wavelength is small. In the field curvature diagram, the S curve represents the sagittal field curvature at a wavelength of 550nm, and the T curve represents the meridian field curvature at a wavelength of 550nm. It can be seen that the field curvature of the optical system is small, the field curvature and astigmatism of each field of view are well corrected, and the center and edge of the field of view have clear images. From the distortion diagram (DISTORTION), it can be seen that the image deformation caused by the main beam is small, and the imaging quality of the system is excellent. Therefore, the longitudinal spherical aberration, field curvature and distortion of the optical system are well controlled, so that the optical system has good imaging quality.

[0126] Embodiment 3:

[0127] like Fig. 9 As shown, in this embodiment, the projection zoom lens comprises a first fixed group G1, a zoom group G2, a second fixed group G3, a focusing group G4, a galvanometer G5, a prism G6 and a protective glass CG which are sequentially arranged along the optical axis direction. The first fixed group G1 comprises a first lens L1 with negative optical power, a second lens L2 with positive optical power and a third lens L3 with positive optical power. The first lens L1 and the second lens L2 form a first cemented lens group. The zoom group G2 comprises a fourth lens L4 with negative optical power, a fifth lens L5 with negative optical power and a sixth lens L6 with positive optical power. The fifth lens L5 and the sixth lens L6 are The lens L6 forms a second cemented lens group, the second fixed group G3 includes a seventh lens L7 with positive focal power, an eighth lens L8 with negative focal power, a ninth lens L9 with positive focal power, a tenth lens L10 with negative focal power and an eleventh lens L11 with positive focal power, the eighth lens L8, the ninth lens L9 and the tenth lens L10 form a third cemented lens group, the focusing group G4 includes a twelfth lens L12 with positive focal power, a thirteenth lens L13 with positive focal power and a fourteenth lens L14 with negative focal power, the thirteenth lens L13 and the fourteenth lens L14 form a fourth cemented lens group. The fourth lens L4 and the eleventh lens L11 are glass aspherical lenses, and the remaining lenses are glass spherical lenses. The galvanometer G5 is used to vibrate at high frequencies in different directions, so that the image expands the pixel range on the original pixel for a short time, and uses the visual persistence effect to increase the pixels recognized by the human eye, thereby improving the projection resolution; the prism G6 is an equivalent flat plate, which is used to complete the light aggregation for different light source combinations, such as providing appropriate reflection angles and refraction angles for each light. It is a well-known technology for those in the field and will not be repeated here.

[0128] The effective focal length of this optical system is fw=15.167mm, ft=44.7mm, the aperture number Fno=1.65, and the distance ttl from the object side of the first lens L1 to the image plane IMA is 107mm; it can be seen that this optical system can achieve large zoom, large aperture, and miniaturized design. The photosensitive chip at the image plane IMA can use a digital micromirror device (DMD).

[0129] Specifically, the values ​​of the parameters of the lens in this embodiment are as shown in Table 5 below:

[0130] Table 5

[0131]

[0132]

[0133] See also Fig. 9 and Fig.10 , which respectively correspond to the structural schematic diagrams of the wide-angle end and the telephoto end of the projection zoom lens of Example 3, wherein the surface number S0 represents the object plane, the surface numbers S1 to S23 represent the mirror surfaces from the object side of the first lens L1 to the image side of the fourteenth lens L14 in sequence, the cemented surface of the cemented lens group is regarded as one surface, STO represents the aperture, and the surface numbers S24, S26, S28, and S30 represent the galvanometer G5, the prism G6, the protective glass CG, and the digital micromirror device ( The surface numbers S25, S27, S29, and S31 represent the image side of the galvanometer G5, prism G6, protective glass CG, and digital micromirror device (DMD) respectively. d1 represents the axial gap between the first fixed group G1 and the zoom group G2, d2 represents the axial gap between the zoom group G2 and the aperture STO, d3 represents the axial gap between the second fixed group G2 and the focus group G4, and d4 represents the axial gap between the focus group G4 and the galvanometer G5. The moving relationship of the zoom group G2 is shown in d1 and d2 in Table 6, and the moving relationship of the focus group G4 is shown in d3 and d4 in Table 6; the focus group G4 is responsible for the focusing effect of different frames to achieve the transformation of the projection distance from 1.5m to 7m, and supports the transformation of the projection size from 11inch to 158inch.

[0134] Table 6

[0135] Interval(mm) d1 d2 d3 d4 Wide-angle end 0.73 17.76 2.01 1.68 Telephoto end 16.88 1.61 2.17 1.51

[0136] In this embodiment, the mirror equation of each aspherical lens satisfies the following expression:

[0137]

[0138] In the formula, Z is the sagittal height, c is the inverse of the radius of curvature, c = 1 / R, R is the radius of curvature, y is the radial coordinate, k is the coefficient of the conic quadratic curve, α 4 , α 6 , α 8 , α 10 , α 12 , α 14 is the high-order coefficient of the aspheric surface. The specific parameters are shown in Table 7.

[0139] Table 7

[0140] S6 S7 S17 S18 R 51.58554 11.68529 28.64516 -45.9447 k 9.745324 0.43172 -1.43792 1.993206 <![CDATA[α 4 ]]> 1.52E-05 -3.95E-05 -1.62E-05 1.59E-06 <![CDATA[α 6 ]]> 4.82E-07 2.76E-07 -2.63E-08 -4.59E-08 <![CDATA[α 8 ]]> -6.47E-09 -4.92E-09 7.10E-10 3.07E-10 <![CDATA[α 10 ]]> 6.01E-11 -2.60E-11 -6.18E-12 -1.79E-12 <![CDATA[α 12 ]]> -1.73E-13 6.47E-13 1.44E-14 -3.11E-15 <![CDATA[α 14 ]]> 0 0 0 0

[0141] Fig.11 This is the wide-angle end aberration diagram of this embodiment, Fig.12The aberration diagrams at the telephoto end of this embodiment include the longitudinal spherical aberration diagram (LONGITUD INAL SPHERICAL ABER.), field curvature diagram (ASTIGMATIC FIELD CURVES) and distortion diagram (DISTORTION) of the optical system. Among them, the longitudinal spherical aberration diagram represents the deviation of the convergent focus of light of different wavelengths after passing through the lens. The ordinate of the longitudinal spherical aberration diagram represents the normalized pupil coordinate (Normalized Pupil Coordinator) from the center of the pupil to the edge of the pupil, and the abscissa represents the distance from the imaging surface to the intersection of the light and the optical axis (in mm). It can be seen from the longitudinal spherical aberration diagram that the degree of deviation of the convergent focus of light of each wavelength in this embodiment tends to be consistent, the diffuse spots or color halos in the imaging picture are effectively suppressed, and the difference between single wavelength and complex wavelength is small. In the field curvature diagram, the S curve represents the sagittal field curvature at a wavelength of 550nm, and the T curve represents the meridian field curvature at a wavelength of 550nm. It can be seen that the field curvature of the optical system is small, the field curvature and astigmatism of each field of view are well corrected, and the center and edge of the field of view have clear images. From the distortion diagram (DISTORTION), it can be seen that the image deformation caused by the main beam is small, and the imaging quality of the system is excellent. Therefore, the longitudinal spherical aberration, field curvature and distortion of the optical system are well controlled, so that the optical system has good imaging quality.

[0142] Embodiment 4:

[0143] like Fig.13As shown, in this embodiment, the projection zoom lens comprises a first fixed group G1, a zoom group G2, a second fixed group G3, a focusing group G4, a galvanometer G5, a prism G6 and a protective glass CG which are sequentially arranged along the optical axis direction. The first fixed group G1 comprises a first lens L1 with negative optical power, a second lens L2 with positive optical power and a third lens L3 with positive optical power. The first lens L1 and the second lens L2 form a first cemented lens group. The zoom group G2 comprises a fourth lens L4 with negative optical power, a fifth lens L5 with negative optical power and a sixth lens L6 with positive optical power. The fifth lens L5 and the sixth lens L6 are The lens L6 forms a second cemented lens group, the second fixed group G3 includes a seventh lens L7 with positive focal power, an eighth lens L8 with negative focal power, a ninth lens L9 with positive focal power, a tenth lens L10 with negative focal power and an eleventh lens L11 with positive focal power, the eighth lens L8, the ninth lens L9 and the tenth lens L10 form a third cemented lens group, the focusing group G4 includes a twelfth lens L12 with positive focal power, a thirteenth lens L13 with positive focal power and a fourteenth lens L14 with negative focal power, the thirteenth lens L13 and the fourteenth lens L14 form a fourth cemented lens group. The fourth lens L4 and the eleventh lens L11 are glass aspherical lenses, and the remaining lenses are glass spherical lenses. The galvanometer G5 is used to vibrate at high frequencies in different directions, so that the image expands the pixel range on the original pixel for a short time, and uses the visual persistence effect to increase the pixels recognized by the human eye, thereby improving the projection resolution; the prism G6 is an equivalent flat plate, which is used to complete the light aggregation for different light source combinations, such as providing appropriate reflection angles and refraction angles for each light. It is a well-known technology for those in the field and will not be repeated here.

[0144] The effective focal length of this optical system is fw=15.17mm, ft=44.59mm, the aperture number Fno=1.62, and the distance ttl from the object side of the first lens L1 to the image plane IMA is 102.5mm. It can be seen that this optical system can achieve large zoom, large aperture, and miniaturized design. The photosensitive chip at the image plane IMA can use a digital micromirror device (DMD).

[0145] Specifically, the values ​​of the parameters of the lens in this embodiment are as shown in Table 8 below:

[0146] Table 8

[0147]

[0148]

[0149] See also Fig.13 and Fig.14, which respectively correspond to the structural schematic diagrams of the wide-angle end and the telephoto end of the projection zoom lens of Example 4, wherein the surface number S0 represents the object plane, the surface numbers S1 to S23 represent the mirror surfaces from the object side of the first lens L1 to the image side of the fourteenth lens L14 in sequence, the cemented surface of the cemented lens group is regarded as one surface, STO represents the aperture, and the surface numbers S24, S26, S28, and S30 represent the galvanometer G5, the prism G6, the protective glass CG, and the digital micromirror device ( The surface numbers S25, S27, S29, and S31 represent the image side of the galvanometer G5, prism G6, protective glass CG, and digital micromirror device (DMD) respectively. d1 represents the on-axis gap between the first fixed group G1 and the zoom group G2, d2 represents the on-axis gap between the zoom group G2 and the aperture STO, d3 represents the on-axis gap between the second fixed group G2 and the focus group G4, and d4 represents the on-axis gap between the focus group G4 and the galvanometer G5. The moving relationship of the zoom group G2 is shown in d1 and d2 in Table 9, and the moving relationship of the focus group G4 is shown in d3 and d4 in Table 9; the focus group G4 is responsible for the focusing effect of different frames to achieve the transformation of the projection distance from 1.5m to 7m, and supports the transformation of the projection size from 11inch to 158inch.

[0150] Table 9

[0151] Interval(mm) d1 d2 d3 d4 Wide-angle end 0.60 15.33 4.34 2.18 Telephoto end 14.16 1.77 5.02 1.50

[0152] In this embodiment, the mirror equation of each aspherical lens satisfies the following expression:

[0153]

[0154] In the formula, Z is the sagittal height, c is the inverse of the radius of curvature, c = 1 / R, R is the radius of curvature, y is the radial coordinate, k is the coefficient of the conic quadratic curve, α 4 , α 6 , α 8 , α 10 , α 12 , α 14 is the high-order coefficient of the aspheric surface. The specific parameters are shown in Table 7.

[0155] Table 10

[0156] S6 S7 S17 S18 R 88.96128 11.6421 30.66016 -35.1131 k 32.39566 0.945045 -2.25097 1.900538 <![CDATA[α 4 ]]> 7.88E-05 1.63E-05 -2.16E-05 1.95E-06 <![CDATA[α 6 ]]> -5.88E-07 -8.57E-07 -4.62E-09 -4.24E-08 <![CDATA[α 8 ]]> 6.43E-09 -6.25E-09 5.37E-10 2.11E-11 <![CDATA[α 10 ]]> -3.53E-11 1.40E-10 -4.93E-12 4.83E-13 <![CDATA[α 12 ]]> 1.19E-13 -2.34E-12 1.18E-14 -1.23E-14 <![CDATA[α 14 ]]> 0 0 0 0

[0157] Fig.15 This is the wide-angle end aberration diagram of this embodiment, Fig.16The aberration diagrams at the telephoto end of this embodiment include the longitudinal spherical aberration diagram (LONGITUD INAL SPHERICAL ABER.), field curvature diagram (ASTIGMATIC FIELD CURVES) and distortion diagram (DISTORTION) of the optical system. Among them, the longitudinal spherical aberration diagram represents the deviation of the convergent focus of light of different wavelengths after passing through the lens. The ordinate of the longitudinal spherical aberration diagram represents the normalized pupil coordinate (Normalized Pupil Coordinator) from the center of the pupil to the edge of the pupil, and the abscissa represents the distance from the imaging surface to the intersection of the light and the optical axis (in mm). It can be seen from the longitudinal spherical aberration diagram that the degree of deviation of the convergent focus of light of each wavelength in this embodiment tends to be consistent, the diffuse spots or color halos in the imaging picture are effectively suppressed, and the difference between single wavelength and complex wavelength is small. In the field curvature diagram, the S curve represents the sagittal field curvature at a wavelength of 550nm, and the T curve represents the meridian field curvature at a wavelength of 550nm. It can be seen that the field curvature of the optical system is small, the field curvature and astigmatism of each field of view are well corrected, and the center and edge of the field of view have clear images. From the distortion diagram (DISTORTION), it can be seen that the image deformation caused by the main beam is small, and the imaging quality of the system is excellent. Therefore, the longitudinal spherical aberration, field curvature and distortion of the optical system are well controlled, so that the optical system has good imaging quality.

[0158] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0159] The above-described embodiments only express the more specific and detailed embodiments described in this application, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of this application, which all belong to the protection scope of this application. Therefore, the protection scope of the patent in this application shall be based on the attached claims.

Claims

1. A projection zoom lens, characterized in that: The projection zoom lens comprises a first fixed group (G1), a zoom group (G2), a second fixed group (G3) and a focus group (G4) which are sequentially arranged along an optical axis direction; the first fixed group (G1) comprises a first lens (L1) with negative optical power, a second lens (L2) with positive optical power and a third lens (L3) with positive optical power; the first lens (L1) and the second lens (L2) form a first cemented lens group; the zoom group (G2) comprises a fourth lens (L4) with negative optical power, a fifth lens (L5) with negative optical power and a sixth lens (L6) with positive optical power; the fifth lens (L5) and the sixth lens (L6) form a second cemented lens group; the second fixed group (G3) comprises a seventh lens (L1) with positive optical power and a seventh lens (L3) with positive optical power; L7), an eighth lens (L8) with negative focal power, a ninth lens (L9) with positive focal power, a tenth lens (L10) with negative focal power and an eleventh lens (L11) with positive focal power, the ninth lens (L9) and the tenth lens (L10) forming a third cemented lens group, the focusing group (G4) comprising a twelfth lens (L12) with positive focal power, a thirteenth lens (L13) with positive focal power and a fourteenth lens (L14) with negative focal power, the thirteenth lens (L13) and the fourteenth lens (L14) forming a fourth cemented lens group, the first lens (L1) to the fourteenth lens (L14) are arranged in sequence along the optical axis, and the zoom group (G2) and the focusing group (G4) can move along the optical axis to adjust the focus; The projection zoom lens also meets the following conditions: 14mm≤fw≤16mm,42mm≤ft≤46mm; Wherein, fw is the focal length of the wide-angle end of the projection zoom lens, and ft is the focal length of the telephoto end of the projection zoom lens.

2. The projection zoom lens according to claim 1, wherein: The projection zoom lens also meets the following conditions: Among them, EFL1 is the combined focal length of the first fixed group (G1), EFL3 is the combined focal length of the second fixed group (G3), EFL2 is the combined focal length of the zoom group (G2), and EFL4 is the combined focal length of the focusing group (G4).

3. The projection zoom lens according to claim 1, wherein: The projection zoom lens also meets the following conditions: Wherein, thi12w is the on-axis gap between the first fixed group (G1) and the zoom group (G2) at the wide-angle end, ttl is the distance from the first lens (L1) to the image plane (IMA), and thi23t is the on-axis distance between the zoom group (G2) and the second fixed group (G3) at the telephoto end.

4. The projection zoom lens according to claim 1, wherein: The projection zoom lens also meets the following conditions: Wherein, thi34w is the axial gap between the second fixed group (G3) and the focusing group (G4) at the wide-angle end, and ttl is the distance from the first lens (L1) to the image plane (IMA).

5. The projection zoom lens according to claim 1, wherein: The projection zoom lens also meets the following conditions: Wherein, dwt is the moving distance of the zoom group (G2) from the wide-angle end to the telephoto end, and ttl is the distance from the first lens (L1) to the image plane (IMA).

6. The projection zoom lens according to claim 1, wherein: The projection zoom lens also meets the following conditions: Wherein, EPDt is the entrance pupil diameter at the telephoto end of the projection zoom lens.

7. The projection zoom lens according to claim 1, wherein: The projection zoom lens also meets the following conditions: -1°≤CRAw≤1°, -1.5°≤CRAt≤1.5° Wherein, CRAw is the angle between the principal ray of the maximum imaging circle at the wide-angle end of the projection zoom lens and the image plane (IMA), and CRAt is the angle between the principal ray of the maximum imaging circle at the telephoto end of the projection zoom lens and the image plane (IMA).

8. The projection zoom lens according to claim 1, wherein: The projection zoom lens also meets the following conditions: Wherein, ind7 is the refractive index of the seventh lens (L7) at a wavelength of 550 nm, ind12 is the refractive index of the twelfth lens (L12) at a wavelength of 550 nm, thi7 is the median thickness of the seventh lens (L7), and thi12 is the median thickness of the twelfth lens (L12).

9. The projection zoom lens according to claim 1, wherein: The projection zoom lens also meets the following conditions: Wherein, SD1 is the effective semi-aperture of the first lens (L1), and SD12 is the effective semi-aperture of the twelfth lens (L12).

10. The projection zoom lens according to claim 1, wherein: The projection zoom lens further comprises a stop (STO), wherein the stop (STO) is located between the sixth lens (L6) and the seventh lens (L7) and is fixed to the second fixed group (G3).

Images