A projection zoom optical system

Abstract

This invention relates to the field of optical imaging system technology and discloses a projection zoom optical system. Along the optical axis from the image source side to the projection side, the system comprises: a light valve, a prism group, an image bias mirror, a first group of lenses consisting of a first lens with positive optical power, a second group of lenses consisting of a second lens with positive optical power, a third lens with positive optical power, a fourth lens with negative optical power, and a fifth lens with positive optical power, an aperture stop, a third group of lenses consisting of a sixth lens with positive optical power, a fourth group of lenses consisting of a seventh lens with positive optical power, a fifth group of lenses consisting of an eighth lens with positive optical power and a ninth lens with negative optical power, and a sixth group of lenses consisting of a tenth lens with negative optical power and an eleventh lens with negative optical power. This system can improve the performance of zoom lenses with lower cost and lower complexity, while also improving the quality and clarity of the projected image.

Description

Technical Field

[0001] This invention relates to the field of optical imaging system technology, and more particularly to a projection zoom optical system. Background Technology

[0002] Currently, projection display technology is widely used in education, homes, military, transportation, offices, and many other fields, with huge market demand. However, lens technology, as one of the core components of projection displays, faces many challenges, including complex design and difficult manufacturing, especially in ensuring high image quality while considering cost and miniaturization. Improving product performance, particularly maintaining image clarity during zoom imaging, is one of the major challenges in current lens design.

[0003] Current zoom projection lens technology typically employs a system of zoom and compensation group. After zooming, a second focusing is required through the compensation group. This approach is cumbersome and produces poor image quality, making it difficult to meet the demands of high-quality projection.

[0004] Therefore, there is an urgent need for a projection zoom optical system that can improve the performance of zoom lenses at a lower cost and with less complexity, while also improving the quality and clarity of projected images. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a projection zoom optical system, comprising the following components along the optical axis from the image source side to the projection side:

[0006] An optical valve, the optical valve being used to provide a high-resolution image beam;

[0007] The prism assembly includes: a TIR total internal reflection prism and an illumination prism;

[0008] The TIR total internal reflection prism is used to enhance the brightness and contrast of the image beam, and the illumination prism is used to improve the uniformity and distribution of the image beam.

[0009] An image biasing mirror, used to adjust the orientation and position of an image;

[0010] The first group of lenses consists of a first lens with positive optical power;

[0011] The second group of lenses consists of a second lens with positive optical power, a third lens with positive optical power, a fourth lens with negative optical power, and a fifth lens with positive optical power; wherein the third lens, the fourth lens, and the fifth lens are combined to form a cemented triode lens.

[0012] Aperture;

[0013] The third group of lenses consists of a sixth lens with positive optical power;

[0014] The fourth group of lenses consists of a seventh lens with positive optical power;

[0015] The fifth group of lenses consists of an eighth lens with positive optical power and a ninth lens with negative optical power; the eighth lens and the ninth lens are combined to form a cemented doublet lens.

[0016] The sixth group of lenses consists of a tenth lens (L10) with negative optical power and an eleventh lens with negative optical power.

[0017] Furthermore, the first lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the eighth lens, and the ninth lens are all spherical lenses;

[0018] The second lens, the seventh lens, the tenth lens, and the eleventh lens are all aspherical lenses.

[0019] Furthermore, the seventh lens, the tenth lens, and the eleventh lens are all plastic lenses.

[0020] Furthermore, the first lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the eighth lens, and the ninth lens are all glass lenses.

[0021] Furthermore, the fourth lens has an Abbe number of 20 to 30 and a thickness of 0.5 mm to 2 mm.

[0022] Furthermore, the refractive index of the fourth lens is greater than 1.7, while the refractive indices of the third and fifth lenses are less than 1.7.

[0023] Furthermore, the Abbe number of the eighth lens is between 0 and 65, and the Abbe number of the ninth lens is between 0 and 65.

[0024] Furthermore, the eighth lens is a biconvex lens, and the ninth lens is a biconcave lens.

[0025] Furthermore, the distance from the light valve to the first lens is denoted as BFL, and the distance from the vertex of the first lens surface to the vertex of the eleventh lens surface is denoted as L, satisfying the relationship: 0.0 <BFL / L<0.5。

[0026] Furthermore, the first group of lenses, the second group of lenses, the third group of lenses, the fourth group of lenses, the fifth group of lenses, and the sixth group of lenses constitute a zoom lens group;

[0027] The equivalent focal length of the zoom lens group is F1, the equivalent focal length of the first lens group is F2, the equivalent focal length of the second lens group is F3, the equivalent focal length of the third lens group is F4, the equivalent focal length of the fourth lens group is F5, the equivalent focal length of the fifth lens group is F6, and the equivalent focal length of the sixth lens group (G6) is F7, and the following conditions are satisfied:

[0028] 2<|F2 / F1|<5; 10<|F3 / F1|<50; 1<|F4 / F1|<4; 5<|F5 / F1|<10; 2<|F6 / F1|<5; 0<|F7 / F1|<3.

[0029] The embodiments of the present invention have the following technical effects:

[0030] This solution employs an innovative design combining internal zoom and external compensation. The zoom function is implemented internally within the lens, while an external compensation mechanism adjusts the focal length. External compensation primarily expands the projection size range to meet diverse projection size requirements. The internal zoom fully utilizes the advantages of aspherical surfaces, effectively reducing the shift of the optimal focal plane, thus resolving the blurring issue caused by focal plane shift during zooming. This integrated and optimized design effectively addresses focus shift during zooming, improving lens performance and image quality. In contrast, zooming with compensation requires more steps and adjustments, typically resulting in higher cost and complexity. This improvement effectively reduces focal plane shift, enhances image quality, and achieves good zoom performance at a lower cost and with less complexity. This design is commonly used in scenarios requiring high-quality projection, such as conference rooms and cinemas, providing flexible zoom functionality without sacrificing image sharpness. Attached Figure Description

[0031] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the structure of a zoom projection system provided in an embodiment of the present invention;

[0033] Figure 2 This is a schematic diagram of another zoom projection system provided in an embodiment of the present invention;

[0034] Figure 3 This is a schematic diagram of TV distortion of the projection system image provided in an embodiment of the present invention;

[0035] Figure 4 This is a schematic diagram of point spot imaging on a screen under a certain field of view, provided by an embodiment of the present invention, for three different wavelengths of light.

[0036] Figure 5 This is a schematic diagram showing the aberration values ​​between the three different wavelengths of light and the dominant wavelength light along the x-axis and y-axis under normalized field-of-view conditions provided in the embodiments of the present invention. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0038] Figure 1 This is a schematic diagram of a zoom projection system provided in Embodiment 1 of the present invention. See also... Figure 1 Specifically, it includes the following along the optical axis from the image source side to the projection side:

[0039] An optical valve, the optical valve being used to provide a high-resolution image beam;

[0040] Specifically, the optical valve is a DMD chip or an LCos chip, and the optical valve is an optical modulation element.

[0041] The prism assembly includes: a TIR total internal reflection prism and an illumination prism;

[0042] The TIR total internal reflection prism is used to enhance the brightness and contrast of the image beam, and the illumination prism is used to improve the uniformity and distribution of the image beam.

[0043] An image biasing mirror, used to adjust the orientation and position of an image;

[0044] The first group of lenses G1 consists of a first lens L1 with positive optical power;

[0045] The second group of lenses G2 consists of a second lens L2 with positive optical power, a third lens L3 with positive optical power, a fourth lens L4 with negative optical power, and a fifth lens L5 with positive optical power; wherein the third lens L3, the fourth lens L4, and the fifth lens L5 are combined to form a cemented triode lens.

[0046] The aperture stop moves with the second group of lenses G2, effectively improving the system's coma problem;

[0047] The third group of lenses G3 consists of a sixth lens L6 with positive optical power;

[0048] The fourth group of lenses G4 consists of a seventh lens L7 with positive optical power;

[0049] The fifth group of lenses G5 consists of an eighth lens L8 with positive optical power and a ninth lens L9 with negative optical power; the eighth lens L8 and the ninth lens L9 are combined to form a cemented doublet lens.

[0050] The sixth group of lenses G6 consists of a tenth lens L10 with negative optical power and an eleventh lens L11 with negative optical power. Optionally, the tenth lens L10 and the eleventh lens L11 are a front group, and their relative positions can be fixed or movable. Fixing them simplifies the system structure, while relative movement allows for better correction of system distortion.

[0051] In some embodiments, to effectively achieve system distortion compensation, the system can be transformed so that the tenth lens L10 forms the sixth group of lenses G6, and the eleventh lens L11 forms the seventh group of lenses G7, as shown below. Figure 2 As shown.

[0052] In this invention, the first lens L1, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the eighth lens L8, and the ninth lens L9 are all spherical lenses; the second lens L2, the seventh lens L7, the tenth lens L10, and the eleventh lens L11 are all aspherical lenses.

[0053] In this invention, the seventh lens L7, the tenth lens L10, and the eleventh lens L11 are all plastic lenses; the first lens L1, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the eighth lens L8, and the ninth lens L9 are all glass lenses.

[0054] In the present invention, the Abbe number of the fourth lens L4 is from 20 to 30, and the thickness is from 0.5 mm to 2 mm; the refractive index of the fourth lens L4 is greater than 1.7, and the refractive indices of the third lens L3 and the fifth lens L5 are less than 1.7; the Abbe number of the eighth lens L8 is from 0 to 65, and the Abbe number of the ninth lens L9 is from 0 to 65; the eighth lens L8 is a biconvex lens, and the ninth lens L9 is a biconcave lens.

[0055] In the present invention, the distance from the light valve to the first lens L1 is denoted as BFL, and the distance from the vertex of the surface of the first lens L1 to the vertex of the surface of the eleventh lens L11 is denoted as L, and they satisfy the relational expression: 0.0 < BFL / L < 0.5; the first lens group G1, the second lens group G2, the third lens group G3, the fourth lens group G4, the fifth lens group G5, and the sixth lens group G6 lenses form a zoom lens group; the equivalent focal length of the zoom lens group is F1, the equivalent focal length of the first lens group G1 is F2, the equivalent focal length of the second lens group G2 is F3, the equivalent focal length of the third lens group G3 is F4, the equivalent focal length of the fourth lens group G4 is F5, the equivalent focal length of the fifth lens group G5 is F6, and the equivalent focal length of the sixth lens group G6 is F7, and they satisfy the following conditions:

[0056] 2 < |F2 / F1| < 5; 10 < |F3 / F1| < 50; 1 < |F4 / F1| < 4; 5 < |F5 / F1| < 10; 2 < |F6 / F1| < 5; 0 < |F7 / F1| < 3.

[0057] It can be seen from this that a zoom projection imaging system proposed by the present invention includes a light valve, a prism group, an image offset mirror, and a zoom lens group. The zoom lens group totally includes 11 lenses, among which there are 4 aspherical lenses and 7 spherical lenses. The optical power of the lenses in the optical system will directly affect astigmatism, curvature of field, distortion, axial chromatic aberration, and lateral chromatic aberration. Therefore, different combinations of positive and negative optical powers will also play a certain role in aberration correction. Thus, the optical powers of the 11 lenses in the present invention are distributed as positive, positive, positive, negative, positive, positive, positive, positive, negative, negative, negative, and the total optical power of the zoom lens group is positive optical power. Through the above combination, the clarity of the picture resolution is maintained during the zoom process. By adopting the design of moving the entire zoom lens group, a larger picture size range can be achieved. This method effectively improves the high-resolution imaging quality of the projection and ensures the clarity and detail performance of the image.

[0058] Specifically, in the zoom lens system, the cemented triplet lens is the core component. While correcting aberrations, the appropriate selection of glass materials and optical power distribution effectively balances aberrations, temperature drift, and manufacturability. The cemented triplet lens is mainly used to correct chromatic aberration and balance system temperature; therefore, materials with significantly different Abbe numbers are preferred. Thus, the Abbe number Vd of the fourth lens L4 is selected between 20 and 30. Choosing materials with Abbe numbers in this range effectively reduces the impact of thermal expansion and contraction on system temperature drift and improves lens resolution. The third lens L3 and the fifth lens L5 are made of materials with low refractive indices to neutralize the high refractive index and negative optical power of the fourth lens L4, reducing spherical aberration, coma, astigmatism, and other aberrations (generally, the higher the refractive index, the greater the absorption of blue light, and the lower the light transmittance). Furthermore, the thickness of the fourth lens L4 needs to be designed and controlled between 0.5 and 2 mm to suppress the reduction in transmittance.

[0059] The eighth lens L8 and the ninth lens L9 form a cemented doublet lens. The Abbe number Vd of the eighth lens L8 and the ninth lens L9 is selected to be less than 65. The reason for this selection is that the residual chromatic aberration of the lens is small, and materials with similar Abbe numbers need to be selected for matching. Furthermore, by designing the eighth lens L8 and the ninth lens L9 as a combination of biconvex and biconcave, no additional chromatic aberration will be generated during zoom movement, which will affect the system performance.

[0060] In this embodiment of the invention, the effective focal lengths of each lens (L1~L11) in the optical system are shown in the table below:

[0061]

[0062] Figure 3 This is a schematic diagram of TV distortion in the projection system image provided in an embodiment of the present invention, as shown below. Figure 3 As shown, in the coordinate system on the left, the horizontal coordinate represents the magnitude of the field curvature, in mm; the vertical coordinate represents the normalized image height, which has no unit; from Figure 3 It can be seen that the projection system provided in this embodiment effectively controls the field curvature in the horizontal direction, that is, during imaging, the difference in image quality between the center and the periphery is small; in the coordinate system on the right, the horizontal coordinate represents the magnitude of distortion, in percentage; the vertical coordinate represents the normalized image height, which has no unit; from Figure 3 It can be seen that the projection system provided in this embodiment has controlled the imaging distortion in the horizontal direction.

[0063] Figure 4The distribution of light spots on the imaging screen for three wavelengths (0.45μm, 0.55μm, and 0.62μm) under different field-of-view conditions is shown. The normalized spot diagrams demonstrate the impact of different wavelengths on the imaging effect. 0.45μm light: short wavelength light, with a smaller spot size, exhibiting higher resolution; 0.55μm light: medium wavelength light, with a spot size between short and long wavelength light; 0.62μm light: long wavelength light, with a larger spot size, exhibiting lower resolution.

[0064] Figure 5 The rayfan plot contains 10 different charts, each corresponding to a normalized field of view condition. The horizontal axis represents the pupil height position under a specific field of view condition, which is related to the height of the light entering the optical system and reflects the angle of incidence of different rays. The vertical axis represents the error values ​​between each wavelength ray (0.45μm, 0.55μm, 0.62μm) and the principal ray, i.e., aberrations. These errors usually originate from design flaws or material properties of the optical system and reflect the possible deviations that may occur during imaging at different wavelengths. Each field of view chart contains two parts, representing the symmetry relationship centered on the optical axis. This indicates that for each wavelength ray, there are similar patterns and trends in aberrations along the x and y axes.

[0065] This invention uses lenses made only of glass and plastic, resulting in lighter weight and lower manufacturing costs. The lens consists of 11 elements, and the use of cemented lenses reduces chromatic aberration and image distortion, ensuring image quality and reducing overall system length and size. By rationally setting and adjusting the focal lengths of six groups, and employing an internal zoom and external compensation scheme, the compensation is solely for accommodating a wider projection size range. The internal zoom fully utilizes the advantages of aspherical surfaces, effectively reducing the shift of the optimal focal plane and resolving the image blurring caused by focal plane shift during zooming. The image is clear and requires no secondary focusing.

[0066] It should be noted that the terminology used in this invention is for describing specific embodiments only and is not intended to limit the scope of this application. As shown in this specification, unless the context clearly indicates otherwise, words such as "a," "an," "an," and / or "the" do not specifically refer to the singular and may include the plural. The terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, or apparatus that includes said element.

[0067] It should also be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Unless otherwise expressly specified and limited, the terms "installed," "connected," "linked," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components. For those skilled in the art, the specific meaning of the above terms in the present invention can be understood according to the specific circumstances.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the technical solutions of the embodiments of the present invention.

Claims

1. A projection zoom optical system, characterized in that, Along the optical axis from the image source side to the projection side, the sequence is as follows: An optical valve, the optical valve being used to provide a high-resolution image beam; The prism assembly includes: a TIR total internal reflection prism and an illumination prism; The TIR total internal reflection prism is used to enhance the brightness and contrast of the image beam, and the illumination prism is used to improve the uniformity and distribution of the image beam. An image biasing mirror, used to adjust the orientation and position of an image; The first group of lenses (G1) consists of a first lens (L1) with positive optical power; The second group of lenses (G2) consists of a second lens (L2) with positive optical power, a third lens (L3) with positive optical power, a fourth lens (L4) with negative optical power, and a fifth lens (L5) with positive optical power; wherein the third lens (L3), the fourth lens (L4), and the fifth lens (L5) are combined to form a cemented triode lens; An aperture stop that moves with the second group of lenses (G2) to improve system coma. The third group of lenses (G3) consists of a sixth lens (L6) with positive optical power; The fourth group of lenses (G4) consists of a seventh lens (L7) with positive optical power; The fifth group of lenses (G5) consists of an eighth lens (L8) with positive optical power and a ninth lens (L9) with negative optical power; the eighth lens (L8) and the ninth lens (L9) are combined to form a cemented doublet; the eighth lens (L8) is a biconvex lens and the ninth lens (L9) is a biconcave lens; the Abbe number of the eighth lens (L8) is 0 to 65, and the Abbe number of the ninth lens (L9) is 0 to 65. The sixth group of lenses (G6) consists of a tenth lens (L10) with negative optical power and an eleventh lens (L11) with negative optical power. The relative positions of the tenth lens (L10) and the eleventh lens (L11) can be fixed or can move relative to each other; The effective focal lengths of the first lens (L1), the second lens (L2), the third lens (L3), the fourth lens (L4), the fifth lens (L5), the sixth lens (L6), the seventh lens (L7), the eighth lens (L8), the ninth lens (L9), the tenth lens (L10), and the eleventh lens (L11) are as follows: 。 2. The projection zoom optical system according to claim 1, characterized in that: The first lens (L1), the third lens (L3), the fourth lens (L4), the fifth lens (L5), the sixth lens (L6), the eighth lens (L8), and the ninth lens (L9) are all spherical lenses; The second lens (L2), the seventh lens (L7), the tenth lens (L10), and the eleventh lens (L11) are all aspherical lenses.

3. The projection zoom optical system according to claim 1, characterized in that: The seventh lens (L7), the tenth lens (L10), and the eleventh lens (L11) are all plastic lenses.

4. The projection zoom optical system according to claim 1, characterized in that: The first lens (L1), the first lens (L2), the third lens (L3), the fourth lens (L4), the fifth lens (L5), the sixth lens (L6), the eighth lens (L8), and the ninth lens (L9) are all glass lenses.

5. A projection zoom optical system according to claim 1, characterized in that: The fourth lens (L4) has an Abbe number of 20 to 30 and a thickness of 0.5 mm to 2 mm.

6. The projection zoom optical system according to claim 1, characterized in that: The refractive index of the fourth lens (L4) is greater than 1.7, while the refractive indices of the third lens (L3) and the fifth lens (L5) are less than 1.

7.

7. The projection zoom optical system according to claim 1, characterized in that: The distance from the light valve to the first lens (L1) is denoted as BFL, and the distance from the vertex of the surface of the first lens (L1) to the vertex of the surface of the eleventh lens (L11) is denoted as L, satisfying the relationship: 0.0 <BFL / L<0.5。 8. The projection zoom optical system according to claim 1, characterized in that: The first group of lenses (G1), the second group of lenses (G2), the third group of lenses (G3), the fourth group of lenses (G4), the fifth group of lenses (G5), and the sixth group of lenses (G6) constitute a zoom lens group; The equivalent focal length of the zoom lens group is F1, the equivalent focal length of the first lens group (G1) is F2, the equivalent focal length of the second lens group (G2) is F3, the equivalent focal length of the third lens group (G3) is F4, the equivalent focal length of the fourth lens group (G4) is F5, the equivalent focal length of the fifth lens group (G5) is F6, and the equivalent focal length of the sixth lens group (G6) is F7, and the following conditions are satisfied: 2<|F2 / F1|<5; 10<|F3 / F1|<50; 1<|F4 / F1|<4; 5<|F5 / F1|<10; 2<|F6 / F1|<5; 0<|F7 / F1|<3.

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