Projection zoom lens

Abstract

The utility model 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 the direction of an optical axis, the first fixed group comprises a first lens, a second lens and a third lens, and the zoom 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 utility model belongs to the technical field of optical lenses, and in particular relates to a projection zoom lens. Background Art

[0002] Projectors, with their large screens and wide range of applications, are increasingly gaining popularity in the display industry, finding widespread use in education, home use, and other fields. With the rapid development of the projection market, projectors have become significantly more user-friendly. The lens, as a core component of a projector, determines the range of image size that can be adjusted.

[0003] However, the projection distance and image size of commonly used projections are greatly limited, and cannot be used in various 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 contains multiple lens groups, and 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 lens is 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 automatically adjust to different frames and projection distances and achieve high-quality projection effects. Utility Model Content

[0005] The purpose of the utility model is to address the above-mentioned problems and propose a projection zoom lens, which has a small size, a large aperture, an adjustable projection distance and throw ratio, and the total length of the zoom process remains unchanged. It can provide sufficient projection brightness and size, and the projected image 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] In order to achieve the above purpose, the technical solution adopted by the utility model is:

[0007] The utility model provides a projection zoom lens, comprising a first fixed group, a zoom group, a second fixed group and a focus group arranged in sequence along the optical axis direction, the first fixed group comprising 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 forming a first cemented lens group, the zoom group comprising 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 forming a second cemented lens group, the second fixed group comprising 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 forming a second cemented lens group, the second fixed group comprising 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 forming a second cemented lens group, the a seventh lens having a positive optical power, an eighth lens having a negative optical power, a ninth lens having a positive optical power, a tenth lens having a negative optical power, and an eleventh lens having a positive optical power; the ninth lens and the tenth lens form a third cemented lens group; a focusing group includes a twelfth lens having a positive optical power, a thirteenth lens having a positive optical power, and a fourteenth lens having a negative optical power; the thirteenth lens and the fourteenth lens form a fourth cemented lens group; the first to fourteenth lenses are arranged in sequence along the optical axis; and the zoom group and the focusing group are capable of moving along the optical axis 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 further 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 further meets the following conditions:

[0015]

[0016] Wherein, thi12w is the on-axis distance 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 further meets the following conditions:

[0018]

[0019] Wherein, thi34w is the on-axis 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 further meets the following conditions:

[0021]

[0022] Wherein, dwt is the distance the zoom group moves 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 further 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 further 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 further 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 further 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 beneficial effects of the present invention are:

[0037] This lens consists of a first fixed group, a zoom group, a second fixed group, and a focus group, arranged sequentially along the optical axis. Focusing is achieved by moving the zoom group and focus group. It features a compact size, low cost, a large aperture, adjustable projection distance and throw ratio, and a constant overall zoom process. It can provide sufficient projection brightness and size, resulting in a sharp, high-contrast, and accurate color reproduction. It is also temperature-insensitive, has a simple zoom mechanism, and is easy to mass-produce. Zooming is simple and fast. Specifically, the 14-lens architecture is compact, reducing costs while ensuring image quality. The rational distribution of optical power makes the lens structure compact, with a total lens length of less than 130mm. The rational distribution of lenses corrects various aberrations, improving edge image quality and, consequently, image quality. The aperture can reach up to F1.6, enabling the lens to output a higher amount of light. The rational setting of lens materials ensures that the lens does not defocus in ambient conditions of -20°C to +70°C, resulting in more stable operating performance. The 0.33" DMD chip is compatible with this design, offering high pixel count and better image quality, maintaining a clear image during wide-range zooming and focusing, resulting in high-quality projection 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 in Example 1 of the present utility model;

[0039] Figure 2 This is a schematic structural diagram of the telephoto end of the projection zoom lens in Example 1 of the present utility model;

[0040] Figure 3 This is a diagram of longitudinal spherical aberration, astigmatism, and distortion at the wide-angle end of the projection zoom lens in Example 1 of the present utility model;

[0041] Figure 4 This is a diagram of longitudinal spherical aberration, astigmatism, and distortion at the telephoto end of the projection zoom lens in Example 1 of the present utility model;

[0042] Figure 5 This is a schematic structural diagram of the wide-angle end of the projection zoom lens of Example 2 of the present utility model;

[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 utility model;

[0044] Figure 7 This is a diagram showing the longitudinal spherical aberration, astigmatism, and distortion of the projection zoom lens at the wide-angle end of Example 2 of the present utility model;

[0045] Figure 8 This is a diagram of longitudinal spherical aberration, astigmatism, and distortion at the telephoto end of the projection zoom lens in Example 2 of the present utility model;

[0046] Figure 9This is a schematic structural diagram of the wide-angle end of a projection zoom lens according to Embodiment 3 of the present utility model;

[0047] Figure 10 This is a schematic structural diagram of the telephoto end of a projection zoom lens according to Embodiment 3 of the present utility model;

[0048] Figure 11 This is a diagram showing the longitudinal spherical aberration, astigmatism, and distortion of the projection zoom lens at the wide-angle end of Example 3 of the present utility model;

[0049] Figure 12 This is a diagram of longitudinal spherical aberration, astigmatism, and distortion at the telephoto end of the projection zoom lens in Example 3 of the present utility model;

[0050] Figure 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] Figure 14 This is a schematic structural diagram of the telephoto end of a projection zoom lens according to a fourth embodiment of the present invention;

[0052] Figure 15 This is a diagram showing the longitudinal spherical aberration, astigmatism, and distortion of the projection zoom lens at the wide-angle end of Example 4 of the present utility model;

[0053] Figure 16 This is a diagram showing the longitudinal spherical aberration, astigmatism, and distortion of the projection zoom lens at the telephoto end of Example 4 of the present invention.

[0054] Explanation of the reference numerals: G1, first fixed group; G2, zoom group; G3, second fixed group; G4, focusing group; G5, galvanometer; G6, prism; STO, aperture; CG, cover 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 this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts 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 commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing specific embodiments only and are not intended to limit this application.

[0057] A projection zoom lens comprises a first fixed group G1, a zoom group G2, a second fixed group G3, and a focusing group G4, which are sequentially arranged along an optical axis. The first fixed group G1 comprises a first lens L1 having negative focal power, a second lens L2 having positive focal power, and a third lens L3 having positive focal 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 negative focal power, a fifth lens L5 having negative focal power, and a sixth lens L6 having positive focal 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 having positive focal 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 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 first lens L1 to the fourteenth lens L14 are arranged in sequence along the optical axis. The zoom group G2 and the focusing group G4 can move along the optical axis for focusing.

[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 includes fourteen lenses, namely, 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. Preferably, an all-glass structure is adopted, that is, fourteen glass lenses are used.

[0062] The first fixed lens group G1 consists 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 and second lenses L1 and L2 form a first cemented lens group. This first cemented lens group provides excellent chromatic aberration correction, resulting in superior chromatic aberration performance at both telephoto and wide-angle ends. Its flat surface reduces spherical aberration at both wide-angle and telephoto ends, facilitating a wider aperture. The third lens L3 shares the optical power of the second lens L2, preventing excessive surface curvature and improving processability.

[0063] Zoom group G2 consists of 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 and sixth lenses L5 and L6 form a second cemented lens group. The fourth lens L4 helps quickly narrow the light beam, lowering its height and improving distortion and field curvature correction. A glass aspherical lens is preferred for fourth lens L4 to further enhance system integration and resolution. The second cemented lens group provides appropriate chromatic and spherical aberration correction across the entire focal length during movement. The negative optical power of zoom group G2 helps minimize travel distance and reduce overall lens length.

[0064] The second fixed lens group G3 comprises a seventh lens element L7 with positive optical power, an eighth lens element L8 with negative optical power, a ninth lens element L9 with positive optical power, a tenth lens element L10 with negative optical power, and an eleventh lens element L11 with positive optical power. The ninth lens element L9 and the tenth lens element L10 form a third cemented lens group. The seventh lens element L7 has a higher refractive index, reducing surface curvature and facilitating processing. Its reduced thickness also avoids the low short-wavelength transmittance associated with high-refractive-index materials. The seventh lens element L7 and the eighth lens element L8 utilize a combination of positive and negative optical powers to create a height difference in light intensity, providing field curvature compensation and improving the MTF concentration. The ninth lens element L9 in the third cemented lens group has a high Abbe number, while the tenth lens element L10 has a low Abbe number. The combined lens provides sufficient chromatic aberration compensation, and negative dndt materials can be used to compensate for high and low temperatures. The eleventh lens element L11 can share the larger spherical aberration at the rear end, reducing tolerance sensitivity. A glass aspheric lens is preferably used for the eleventh lens element L11 to effectively reduce surface curvature and improve processability.

[0065] 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 eleventh lens L11, the twelfth lens L12, and the thirteenth lens L13 are three positive lenses that share the spherical aberration of the rear group (focusing group G4), reducing spherical aberration sensitivity and helping to improve production yield. The fourth cemented lens group has a flat surface profile, which helps to reduce spherical aberration and correct the incident angle of the principal ray.

[0066] By properly 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. Meeting the above conditions allows the lens to have a certain zoom capability, with a throw ratio of approximately 2.0 at the wide-angle end and approximately 6.0 at the telephoto end, meeting the 3x zoom range required by customers and a wide range of throw ratio variations. Exceeding this range results in the lens having a zoom ratio that is either too large or too small, failing to meet the requirements of miniaturization and large zoom, and is difficult to implement and difficult to mass-produce.

[0067] The zoom group G2 of this projection zoom lens moves smoothly from wide-angle to telephoto, without an inflection point. The focusing group G4 is responsible for maintaining image clarity during zooming and object distance adjustment, with a short travel distance for fast focusing. The materials and optical powers of the second, fifth, ninth, eleventh, and thirteenth lenses, L2, L5, L9, L11, and L13, are combined to achieve temperature compensation, resulting in temperature insensitivity and excellent operational 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 a range, such as 0.87, 0.92, 1.21, and 1.1. Meeting this conditional expression allows the first and second fixed groups G1 and G3 to properly distribute optical power, evenly distributing aberrations from wide-angle to telephoto, preventing significant optical power clustering within the fixed groups and avoiding excessive tolerance concentration. Exceeding this range can lead to excessive aberration concentration within either the first or second fixed group G1 or G2, resulting in high tolerance sensitivity within each group and reduced overall lens manufacturability. EFL2 / EFL4 can take any value within a range, such as -0.52, -0.51, -0.49, and 0.47. Meeting the above conditions allows the zoom group G2 and focus group G4 to achieve a relatively balanced optical power. The zoom group G2 has a low optical power, resulting in minimal aberration changes during movement. Furthermore, the zoom group's sensitivity to internal tolerances is low, effectively ensuring that coaxiality tolerances meet practical requirements when assembled with the lens barrel and cam. The cam is a well-known existing structure in the art, used to drive the zoom group G2 during movement and will not be described in detail here. This further improves the travel range of the zoom group G2 and focus group G4, enhancing overall compactness. Exceeding this range results in the zoom group G2 bearing either too much or too little optical power, resulting in poor travel range and tolerances.

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

[0073]

[0074] Wherein, thi12w is the on-axis distance 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.

[0075] Specifically, thi12w / ttl can take any value within a range, such as 0.005, 0.0053, 0.0068, and 0.008. When the above conditional formula is met, a reasonable air gap exists between the first fixed group G1 and the zoom group G2, preventing lens collisions during movement. This also fully utilizes the internal space, compresses the stroke, and ensures the small size 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 poses a collision risk. thi23t / ttl can take any value within a range, such as 0.015, 0.013, 0.017, and 0.018. When the above conditional formula is met, a suitable gap is left between the zoom group G2 and the second fixed group G2, facilitating the arrangement of the aperture and avoiding collisions. 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]

[0078] Wherein, thi34w is the axial distance 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, and 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, and 101, in units of 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 aspheric 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 a range, such as 0.13, 0.15, 0.16, or 0.18. Meeting the above conditional expression ensures that zoom group G2 has a reasonable travel stroke and no inflection points during movement, facilitating cam design and processing. Furthermore, a reasonably small travel stroke facilitates further miniaturization of the lens, improving compactness. Exceeding the upper limit will result in excessive travel stroke, hindering lens miniaturization. Exceeding the lower limit will result in excessive travel stroke, which can easily lead to concentrated optical power and an inflection point, hindering cam implementation.

[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, and 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 to fully utilize the projected light intensity. If the above conditions are met, the lens has a larger aperture and a higher light-clearance diameter, which is beneficial for 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 a range, such as -0.35°, -0.8°, 0.6°, and -0.9°; CRAt can take any value within a range, such as -1.2°, -0.7°, 0.6°, and -0.1°. When these conditions are met, the telecentricity of the lens is controlled within a very small range, ensuring alignment with the light output direction, improving light output efficiency from the center to the edge of the image, and avoiding uneven brightness. At the same time, the difference between the wide-angle and telephoto ends is small, ensuring good image consistency during zooming. Beyond this range, the telecentricity is excessive, which can easily lead to low light output efficiency, affecting image brightness and uniformity.

[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 a range, such as 0.8, 0.82, 0.86, or 0.88. To satisfy this expression, the seventh lens L7 and the twelfth lens L12 can be made of a reasonably high-refractive-index material and kept thin, minimizing the impact of the high-refractive-index material on short-wavelength blue light. Combined with a multi-layer coating process, this achieves balanced RGB transmittance and avoids color temperature drift. Exceeding this range, the lens material selection is inappropriate, and the thickness is either too large or too small, which is detrimental to processing and transmittance, affecting the user experience.

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

[0097]

[0098] 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 a range, such as 1.72, 1.77, 1.92, or 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. If the above conditional expression is met, the apertures of the first lens L1 and the twelfth lens L12 are not much different. By superimposing the lens barrel and the cam, the diameters of the head and tail of the structure can be basically consistent, which is conducive to the overall miniaturization of the projection system, and also helps to reduce the exposed projection area, improve integration, and reduce the discomfort of exposure. If the upper limit is exceeded, the head size is too large, reducing the aesthetics of the application; if the lower limit is exceeded, 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 is 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. It 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 using specific embodiments. The reference wavelength for the following optical parameters, including effective focal length, Abbe number, and refractive index, is 550 nm, and the other embodiments are the same.

[0103] Example 1:

[0104] like Figure 1-Figure 4As shown, in this embodiment, the projection zoom lens includes a first fixed group G1, a zoom group G2, a second fixed group G3, a focusing group G4, a galvanometer mirror G5, a prism G6, and a protective glass CG, which are sequentially arranged along the optical axis. The first fixed group G1 includes a first lens L1 with negative focal power, a second lens L2 with positive focal power, and a third lens L3 with positive focal power. The first lens L1 and the second lens L2 form a first cemented lens group. The zoom group G2 includes a fourth lens L4 with negative focal power, a fifth lens L5 with negative focal power, and a sixth lens L6 with positive focal power. The fifth lens L5 and The sixth lens L6 forms the second cemented lens group. The second fixed lens 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. 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 vibrate at high frequencies in different directions, briefly expanding the pixel range of the image beyond the original pixel. This utilizes the persistence of vision effect to increase the number of pixels recognized by the human eye, thereby improving projection resolution. The prism G6 is an equivalent flat plate and is used to aggregate light from different light source combinations, such as providing appropriate reflection and refraction angles for each light source. This technique is well known to those skilled in the art and will not be further described here.

[0105] This optical system has an effective focal length of fw = 15.168mm, ft = 44.66mm, an aperture number Fno = 1.64, and a distance ttl from the object side of the first lens L1 to the image plane IMA = 122.07mm. This optical system can achieve a large zoom, a large aperture, and a compact 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] Surface number Surface type Curvature radius (mm) Thickness (mm) Refractive index Abbe number S0 spherical surface unlimited 4000.00 S1 spherical surface 100.82 1.50 1.85 23.78 S2 spherical surface 41.47 7.19 1.50 81.60 S3 spherical surface -246.78 0.10 S4 spherical surface 39.56 5.30 1.84 42.72 S5 spherical surface 205.98 d1 S6 spherical surface 50.54 1.00 1.89 39.20 S7 spherical surface 16.73 9.94 S8 spherical surface -23.07 1.00 1.50 81.60 S9 spherical surface 24.08 2.10 1.85 23.78 S10 spherical surface 106.63 d2 STO spherical surface unlimited 0.62 S11 spherical surface 26.82 2.09 2.00 25.45 S12 spherical surface 338.13 8.24 S13 spherical surface -25.07 1.00 1.70 30.00 S14 spherical surface 18.03 0.85 S15 spherical surface 32.19 6.66 1.50 81.60 S16 spherical surface -11.28 3.00 1.73 28.30 S17 spherical surface -140.18 0.20 S18 spherical surface 76.14 8.00 1.59 68.30 S19 spherical surface -19.90 d3 S20 spherical surface 105.10 2.77 1.96 17.90 S21 spherical surface -75.74 0.10 S22 spherical surface 27.06 8.30 1.59 68.30 S23 spherical surface -29.74 1.60 1.85 23.78 S24 spherical surface 76.10 d4 S25 spherical surface unlimited 3.92 S26 spherical surface unlimited 2.00 1.52 58.58 S27 spherical surface unlimited 2.00 S28 spherical surface unlimited 15.00 1.71 53.83 S29 spherical surface unlimited 1.00 S30 spherical surface unlimited 1.10 1.51 63.36 S31 spherical surface unlimited 0.30 S32 spherical surface unlimited 0.00

[0109] See Figure 1 and Figure 2, which correspond to the structural schematic diagrams of the wide-angle end and the telephoto end of the projection zoom lens of Example 1, respectively. In which, 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, respectively. The cemented surfaces of the cemented lens group are 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 cover glass CG, and the digital micromirror device ( The image side of the DMD (digital micromirror device) is shown in Figure 2. 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 on-axis clearance between the first fixed group G1 and the zoom group G2, d2 represents the on-axis clearance between the zoom group G2 and the aperture STO, d3 represents the on-axis clearance between the second fixed group G2 and the focus group G4, and d4 represents the on-axis clearance between the focus group G4 and the galvanometer G5. The movement relationship of the zoom group G2 is shown in Table 2, as shown by d1 and d2, and the movement relationship of the focus group G4 is shown in Table 2, as shown by d3 and d4. Focus group G4 is responsible for the focus effect of different image formats to achieve the conversion of projection distance from 1.5m to 7m, supporting the conversion of projection size from 11inch to 158inch.

[0110] Table 2

[0111] Interval (mm) d1 d2 d3 d4 Wide-angle end 0.60 20.55 1.03 3.00 Telephoto end 19.27 1.88 2.69 1.35

[0112] Figure 3 This is the aberration diagram at the wide-angle end of this embodiment. Figure 4 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 rays 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 plane to the intersection of the light ray 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 rays of various wavelengths 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 meridional field curvature at a wavelength of 550nm. As can be seen, the optical system exhibits minimal field curvature, with both field curvature and astigmatism well-corrected across all fields of view, resulting in sharp images at both the center and edges of the field of view. The distortion diagram (DISTORTION) shows minimal image distortion caused by the main beam, demonstrating excellent imaging quality. Therefore, the optical system's longitudinal spherical aberration, field curvature, and distortion are all well-controlled, resulting in excellent imaging quality.

[0113] Example 2:

[0114] like Figure 5 As shown, in this embodiment, the projection zoom lens includes a first fixed group G1, a zoom group G2, a second fixed group G3, a focusing group G4, a galvanometer mirror G5, a prism G6, and a protective glass CG, which are sequentially arranged along the optical axis. The first fixed group G1 includes a first lens L1 with negative focal power, a second lens L2 with positive focal power, and a third lens L3 with positive focal power. The first lens L1 and the second lens L2 form a first cemented lens group. The zoom group G2 includes a fourth lens L4 with negative focal power, a fifth lens L5 with negative focal power, and a sixth lens L6 with positive focal power. The fifth lens L5 and The sixth lens L6 forms the second cemented lens group. The second fixed lens 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. 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 vibrate at high frequencies in different directions, briefly expanding the pixel range of the image beyond the original pixel. This utilizes the persistence of vision effect to increase the number of pixels recognized by the human eye, thereby improving projection resolution. The prism G6 is an equivalent flat plate and is used to aggregate light from different light source combinations, such as providing appropriate reflection and refraction angles for each light source. This technique is well known to those skilled in the art and will not be further described here.

[0115] This optical system has an effective focal length of fw = 15.158mm, ft = 44.53mm, an aperture number Fno = 1.63, and a distance ttl from the object side of the first lens L1 to the image plane IMA = 119.34mm. This optical system can achieve a large zoom, a large aperture, and a compact design. The photosensitive chip at the image plane IMA can use a digital micromirror device (DMD).

[0116] Specifically, the values of the parameters of the lens in this embodiment are as shown in Table 3 below:

[0117] Table 3

[0118] Surface number Surface type Curvature radius (mm) Thickness (mm) Refractive index Abbe number S0 spherical surface unlimited 4300.00 S1 spherical surface 100.01 1.50 1.85 23.78 S2 spherical surface 41.50 7.23 1.50 81.60 S3 spherical surface -233.27 0.10 S4 spherical surface 38.75 5.43 1.84 42.72 S5 spherical surface 189.31 d1 S6 spherical surface 49.07 1.00 1.89 39.20 S7 spherical surface 16.48 9.86 S8 spherical surface -22.47 1.00 1.50 81.60 S9 spherical surface 23.77 2.07 1.85 23.78 S10 spherical surface 99.68 d2 STO spherical surface unlimited 0.61 S11 spherical surface 26.09 2.14 2.00 25.45 S12 spherical surface 443.00 7.69 S13 spherical surface -25.94 1.15 1.70 30.00 S14 spherical surface 17.31 0.79 S15 spherical surface 28.05 5.87 1.50 81.60 S16 spherical surface -10.98 3.00 1.75 27.77 S17 spherical surface -317.39 0.20 S18 spherical surface 69.42 8.00 1.62 63.40 S19 spherical surface -19.60 d3 S20 spherical surface 87.09 2.74 1.96 17.90 S21 spherical surface -79.62 0.10 S22 spherical surface 25.35 8.30 1.59 68.30 S23 spherical surface -29.30 1.60 1.85 23.78 S24 spherical surface 57.20 d4 S25 spherical surface unlimited 3.92 S26 spherical surface unlimited 2.00 1.52 58.58 S27 spherical surface unlimited 2.00 S28 spherical surface unlimited 15.00 1.71 53.83 S29 spherical surface unlimited 1.00 S30 spherical surface unlimited 1.10 1.51 63.36 S31 spherical surface unlimited 0.30 S32 spherical surface unlimited 0.00

[0119] See Figure 5 and Figure 6, which correspond to the structural schematic diagrams of the wide-angle end and the telephoto end of the projection zoom lens of Example 2, respectively. In which, 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, respectively. The cemented surfaces of the cemented lens group are 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 image side of the DMD (digital micromirror device) is shown in Figure 4. 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 on-axis clearance between the first fixed group G1 and the zoom group G2, d2 represents the on-axis clearance between the zoom group G2 and the aperture STO, d3 represents the on-axis clearance between the second fixed group G2 and the focus group G4, and d4 represents the on-axis clearance between the focus group G4 and the galvanometer G5. The movement relationship of the zoom group G2 is shown in Table 4 (d1 and d2), and the movement relationship of the focus group G4 is shown in Table 4 (d3 and d4). Focus group G4 is responsible for the focus effect of different image formats to achieve the conversion of projection distance from 1.5m to 7m, supporting the conversion of projection size from 11inch to 158inch.

[0120] Table 4

[0121] 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

[0122] Figure 7 This is the aberration diagram at the wide-angle end 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 rays 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 plane to the intersection of the light ray 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 rays of various wavelengths 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 meridional field curvature at a wavelength of 550nm. As can be seen, the optical system exhibits minimal field curvature, with both field curvature and astigmatism well-corrected across all fields of view, resulting in sharp images at both the center and edges of the field of view. The distortion diagram (DISTORTION) shows minimal image distortion caused by the main beam, demonstrating excellent imaging quality. Therefore, the optical system's longitudinal spherical aberration, field curvature, and distortion are all well-controlled, resulting in excellent imaging quality.

[0123] Example 3:

[0124] like Figure 9 As shown, in this embodiment, the projection zoom lens includes 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. The first fixed group G1 includes a first lens L1 with negative focal power, a second lens L2 with positive focal power and a third lens L3 with positive focal power. The first lens L1 and the second lens L2 form a first cemented lens group. The zoom group G2 includes a fourth lens L4 with negative focal power, a fifth lens L5 with negative focal power and a sixth lens L6 with positive focal power. The fifth lens L5 and the sixth lens L6 are Lens L6 forms the second cemented lens group. The second fixed lens 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 the 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 the 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. Galvanometer G5 is used to vibrate at high frequencies in different directions, briefly expanding the image pixel range beyond the original pixel. This utilizes the persistence of vision effect to increase the number of pixels recognized by the human eye, thereby improving projection resolution. Prism G6, equivalent to a flat plate, is used to aggregate light from different light sources, such as providing appropriate reflection and refraction angles for each light source. This technology is well known to those skilled in the art and will not be elaborated on here.

[0125] This optical system has an effective focal length of fw = 15.167 mm, ft = 44.7 mm, an aperture number of Fno = 1.65, and a distance ttl from the object side of the first lens L1 to the image plane IMA of 107 mm. This optical system can achieve a large zoom, a large aperture, and a compact design. The photosensitive chip at the image plane IMA can use a digital micromirror device (DMD).

[0126] Specifically, the values of the parameters of the lens in this embodiment are as shown in Table 5 below:

[0127] Table 5

[0128] Surface number Surface type Curvature radius (mm) Thickness (mm) Refractive index Abbe number S0 spherical surface unlimited 4300.00 S1 spherical surface 58.53 1.50 1.85 23.78 S2 spherical surface 36.02 7.45 1.50 81.60 S3 spherical surface -569.62 0.10 S4 spherical surface 30.57 5.86 1.62 60.33 S5 spherical surface 108.89 d1 S6 Aspheric 51.59 1.04 1.52 63.90 S7 Aspheric 11.69 7.78 S8 spherical surface -12.60 1.00 1.51 60.48 S9 spherical surface 26.72 1.84 1.85 23.78 S10 spherical surface 1676.41 d2 STO spherical surface unlimited 0.89 S11 spherical surface 27.20 1.97 2.00 25.45 S12 spherical surface 194.83 7.80 S13 spherical surface -30.93 1.00 1.75 27.76 S14 spherical surface 16.09 6.53 1.60 68.34 S15 spherical surface -12.04 1.10 1.67 32.17 S16 spherical surface 48.45 0.20 S17 Aspheric 28.65 4.42 1.81 40.97 S18 Aspheric -45.94 d3 S19 spherical surface -278.82 2.62 1.96 17.94 S20 spherical surface -34.11 0.10 S21 spherical surface 28.48 5.10 1.60 68.34 S22 spherical surface -22.88 1.20 1.81 25.45 S23 spherical surface 181.62 d4 S24 spherical surface unlimited 3.92 S25 spherical surface unlimited 2.00 1.52 58.58 S26 spherical surface unlimited 2.00 S27 spherical surface unlimited 15.00 1.71 53.83 S28 spherical surface unlimited 1.00 S29 spherical surface unlimited 1.10 1.51 63.36 S30 spherical surface unlimited 0.30 S31 spherical surface unlimited 0.00

[0129] See Figure 9 and Figure 10, which correspond to the structural schematic diagrams of the wide-angle end and the telephoto end of the projection zoom lens of Example 3, respectively. In which, 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, respectively. The cemented surfaces of the cemented lens group are 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 image side of the DMD (digital micromirror device) is shown in Figure 6. 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 clearance between the first fixed group G1 and the zoom group G2, d2 represents the on-axis clearance between the zoom group G2 and the aperture STO, d3 represents the on-axis clearance between the second fixed group G2 and the focus group G4, and d4 represents the on-axis clearance between the focus group G4 and the galvanometer G5. The movement relationship of the zoom group G2 is shown in Table 6, as shown by d1 and d2, and the movement relationship of the focus group G4 is shown in Table 6, as shown by d3 and d4. Focus group G4 is responsible for the focus effect of different image formats to achieve the conversion of projection distance from 1.5m to 7m, supporting the conversion of projection size from 11inch to 158inch.

[0130] Table 6

[0131] 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

[0132] In this embodiment, the mirror equation of each aspheric lens satisfies the following expression:

[0133]

[0134] Where 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 conic quadratic curve coefficient, 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.

[0135] Table 7

[0136] S6 S7 S17 S18 R 51.58554 11.68529 28.64516 -45.9447 k 9.745324 0.43172 -1.43792 1.993206 4α 1.52E-05 -3.95E-05 -1.62E-05 1.59E-06 6α 4.82E-07 2.76E-07 -2.63E-08 -4.59E-08 8α -6.47E-09 -4.92E-09 7.10E-10 3.07E-10 1α 6.01E-11 -2.60E-11 -6.18E-12 -1.79E-12 1α -1.73E-13 6.47E-13 1.44E-14 -3.11E-15 1α 0 0 0 0

[0137] Figure 11 This is the aberration diagram at the wide-angle end of this embodiment. Figure 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 plane 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 meridional field curvature at a wavelength of 550nm. As can be seen, the optical system exhibits minimal field curvature, with both field curvature and astigmatism well-corrected across all fields of view, resulting in sharp images at both the center and edges of the field of view. The distortion diagram (DISTORTION) shows minimal image distortion caused by the main beam, demonstrating excellent imaging quality. Therefore, the optical system's longitudinal spherical aberration, field curvature, and distortion are all well-controlled, resulting in excellent imaging quality.

[0138] Example 4:

[0139] like Figure 13As shown, in this embodiment, the projection zoom lens includes 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. The first fixed group G1 includes a first lens L1 with negative focal power, a second lens L2 with positive focal power and a third lens L3 with positive focal power. The first lens L1 and the second lens L2 form a first cemented lens group. The zoom group G2 includes a fourth lens L4 with negative focal power, a fifth lens L5 with negative focal power and a sixth lens L6 with positive focal power. The fifth lens L5 and the sixth lens L6 are Lens L6 forms the second cemented lens group. The second fixed lens 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 the 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 the 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. Galvanometer G5 is used to vibrate at high frequencies in different directions, briefly expanding the image pixel range beyond the original pixel. This utilizes the persistence of vision effect to increase the number of pixels recognized by the human eye, thereby improving projection resolution. Prism G6, equivalent to a flat plate, is used to aggregate light from different light sources, such as providing appropriate reflection and refraction angles for each light source. This technology is well known to those skilled in the art and will not be elaborated on here.

[0140] This optical system has an effective focal length of fw = 15.17 mm, ft = 44.59 mm, an aperture number of Fno = 1.62, and a distance ttl from the object side of the first lens L1 to the image plane IMA of 102.5 mm. This optical system can achieve a large zoom, a large aperture, and a compact design. The photosensitive chip at the image plane IMA can use a digital micromirror device (DMD).

[0141] Specifically, the values of the parameters of the lens in this embodiment are as shown in Table 8 below:

[0142] Table 8

[0143]

[0144]

[0145] See Figure 13 and Figure 14, which correspond to the structural schematic diagrams of the wide-angle end and the telephoto end of the projection zoom lens of Example 4, respectively. In which, 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, respectively. The cemented surfaces of the cemented lens group are 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 cover glass CG, and the digital micromirror device ( The image side of the DMD (digital micromirror device) is shown in Figure 9. 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 clearance between the first fixed group G1 and the zoom group G2, d2 represents the on-axis clearance between the zoom group G2 and the aperture STO, d3 represents the on-axis clearance between the second fixed group G2 and the focus group G4, and d4 represents the on-axis clearance between the focus group G4 and the galvanometer G5. The movement relationship of the zoom group G2 is shown in Table 9 for d1 and d2, and the movement relationship of the focus group G4 is shown in Table 9 for d3 and d4. Focus group G4 is responsible for the focus effect of different image formats to achieve the conversion of projection distance from 1.5m to 7m, supporting the conversion of projection size from 11inch to 158inch.

[0146] Table 9

[0147] 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

[0148] In this embodiment, the mirror equation of each aspheric lens satisfies the following expression:

[0149]

[0150] Where 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 conic quadratic curve coefficient, 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.

[0151] Table 10

[0152]

[0153]

[0154] Figure 15 This is the aberration diagram at the wide-angle end of this embodiment. Figure 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 plane 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 meridional field curvature at a wavelength of 550nm. As can be seen, the optical system exhibits minimal field curvature, with both field curvature and astigmatism well-corrected across all fields of view, resulting in sharp images at both the center and edges of the field of view. The distortion diagram (DISTORTION) shows minimal image distortion caused by the main beam, demonstrating excellent imaging quality. Therefore, the optical system's longitudinal spherical aberration, field curvature, and distortion are all well-controlled, resulting in excellent imaging quality.

[0155] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned 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.

[0156] The above-described embodiments merely represent specific and detailed examples of the present application and should not be construed as limiting the scope of the utility model patent. It should be noted that a person skilled in the art may make various modifications and improvements without departing from the scope of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended 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 focusing group (G4) arranged in sequence along an optical axis. The first fixed group (G1) comprises a first lens (L1) with negative focal power, a second lens (L2) with positive focal power and a third lens (L3) with positive focal 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 focal power, a fifth lens (L5) with negative focal power and a sixth lens (L6) with positive focal 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 focal 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) being arranged in sequence along the optical axis, and the zoom group (G2) and the focusing group (G4) being movable along the optical axis for focusing; The projection zoom lens also meets the following conditions: 14mm≤fw≤16mm,42mm≤ft≤46mm; 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.

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 distance 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 includes a stop (STO), which is located between the sixth lens (L6) and the seventh lens (L7) and is fixed to the second fixed group (G3).

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