Projection lens, projection system and projection device

Abstract

This application discloses a projection lens, a projection system, and a projection device. The projection lens includes a first lens group, an aperture stop, and a second lens group; the first lens group includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens, wherein the first lens has negative refractive power, the second lens has positive refractive power, the third lens has negative refractive power, the fourth lens has negative refractive power, and the fifth lens has positive refractive power; the second lens group includes a sixth lens, a seventh lens, an eighth lens, a ninth lens, and a tenth lens, wherein the sixth lens has positive refractive power, the seventh lens has negative refractive power, the eighth lens has positive refractive power, the ninth lens has positive refractive power, and the tenth lens has positive refractive power; the projection lens satisfies at least one of the following conditions: 8mm ≤ L MAX / Fno≤30mm; 2mm≤EFL / Fno≤16mm; all projection lenses are all-glass spherical lenses. The projection lens provided in this application can achieve a small size while improving the performance of the projection lens.

Description

Technical Field

[0001] This application relates to the field of projection imaging, and more particularly to a projection lens, projection system, and projection device. Background Technology

[0002] As projectors are increasingly used across various fields, the projection lens determines the image quality, and its design is constantly being improved and optimized. Currently, there are greater demands for smaller projector sizes, requiring more compact and smaller projection lens structures. This presents certain challenges to the performance of projection lenses, and the performance of existing lenses needs improvement. Summary of the Invention

[0003] This application provides a projection lens, a projection system, and a projection device, which can improve the performance of the projection lens.

[0004] An embodiment of the first aspect of this application provides a projection lens, which includes, along the optical axis from the magnification side to the reduction side, a first lens group having negative optical power, an aperture stop, and a second lens group having positive optical power. The first lens group includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens arranged sequentially along the optical axis from the magnification side to the reduction side. The first lens has negative refractive power, the second lens has positive refractive power, the third lens has negative refractive power, the fourth lens has negative refractive power, and the fifth lens has positive refractive power. The second lens group includes a sixth lens, a seventh lens, an eighth lens, a ninth lens, and a tenth lens arranged sequentially along the optical axis from the magnification side to the reduction side. The sixth lens has positive refractive power, the seventh lens has negative refractive power, the eighth lens has positive refractive power, the ninth lens has positive refractive power, and the tenth lens has positive refractive power. The focal length of the projection lens is EFL, the aperture number of the projection lens is Fno, and the outer diameter of the largest lens in the projection lens is L. MAX The projection lens must satisfy at least one of the following conditions: 8mm ≤ L MAX / Fno≤30mm; 2mm≤EFL / Fno≤16mm; The lenses of the projection lenses are all all-glass spherical lenses.

[0005] According to an embodiment of the first aspect of this application, the first lens group further includes an eleventh lens, which is disposed between the second lens and the third lens, and the eleventh lens has negative refractive power or positive refractive power; and / or, the second lens group further includes a twelfth lens, which is disposed between the eighth lens and the ninth lens, and the twelfth lens has positive refractive power.

[0006] According to any of the foregoing embodiments of the first aspect of this application, the first lens is a plastic aspherical lens; and / or, at least one of the ninth, tenth, and twelfth lenses is a glass aspherical lens.

[0007] According to any of the foregoing embodiments of the first aspect of this application, the fourth lens and the fifth lens constitute a cemented doublet lens group with positive refractive power; and / or, the sixth lens, the seventh lens and the eighth lens constitute a cemented triplet lens group with negative refractive power.

[0008] According to any of the foregoing embodiments of the first aspect of this application, the fourth lens is a biconcave negative lens, the fifth lens is a biconvex positive lens; and / or, the sixth lens is a biconvex positive lens or a meniscus positive lens, the seventh lens is a biconcave negative lens, and the eighth lens is a biconvex positive lens.

[0009] According to any of the foregoing embodiments of the first aspect of this application, the absolute value of the difference between the refractive index of the fourth lens and the refractive index of the fifth lens is greater than 0.2; and / or, in the sixth lens, the seventh lens, and the eighth lens, the absolute value of the difference between the refractive indices of any two adjacent lenses is greater than 0.2.

[0010] According to any of the foregoing embodiments of the first aspect of this application, the back focal length of the projection lens is BFL, the total optical length of the projection lens is TTL, the image plane height of the projection lens is H, and at least one of the following relationships is satisfied: 0.2≤BFL / EFL≤3; BFL / TTL≥0.1; 5≤TTL / H≤30; 1≤EFL / H≤3.

[0011] According to any of the foregoing embodiments of the first aspect of this application, the focal length of the first lens group is EFL. ZOOM1 The focal length of the second lens group is EFL. ZOOM2 And it satisfies the following relationship: -100.0 < EFL ZOOM1 / EFL < -20.0; 0.3 < EFL ZOOM2 / EFL < 2.6.

[0012] According to any of the foregoing embodiments of the first aspect of this application, the back focal length of the projection lens is BFL, the total optical length of the projection lens is TTL, and the projection lens satisfies at least one of the following relationships: 9mm≤EFL≤20mm; TTL≤180mm; BFL≥20mm; 1.5≤Fno≤3; and the diameter of each lens is not greater than 60mm.

[0013] According to any of the foregoing embodiments of the first aspect of this application, the first lens group includes at least two lenses with a refractive index greater than 1.8; and / or, the second lens group includes at least two lenses with a refractive index greater than 1.8; and / or, the second lens group includes X lenses with a negative ratio of refractive index temperature coefficient to focal length, and satisfies the following relationship: 2≤X≤4.

[0014] The second aspect of this application also provides a projection system, which includes a projection lens according to any of the embodiments of the first aspect described above.

[0015] A third aspect of this application also provides a projection device, which includes a projection lens of any embodiment of the first aspect or a projection system of the second aspect.

[0016] In a projection lens provided in this application, the projection lens includes a first lens group, an aperture stop, and a second lens group. By rationally setting the positive and negative refractive powers of each lens in the first and second lens groups, the projection lens structure is made precise, achieving the goals of low cost, compactness, and small size. By limiting the ratio of the focal length EFL to the aperture number Fno of the projection lens to within [2mm, 16mm], the projection lens has a large aperture, thereby enabling it to have a larger light passage to receive more light, increasing the brightness of the emitted light and thus improving the performance of the projection lens. By limiting the outer diameter L of the largest lens in the projection lens... MAX The ratio of L to the aperture number (Fno) is within [8mm, 30mm]. MAX Under constant conditions, a projection lens with a large aperture can improve its performance. When the aperture (Fno) is within a certain range, the maximum lens outer diameter is also limited, enabling the design of small-sized projection lenses to reduce space occupation. Using all-glass spherical lenses effectively reduces the cost and manufacturing difficulty of the projection lens, improving its applicability. This application improves the performance of the projection lens. Attached Figure Description

[0017] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings, wherein the same or similar reference numerals denote the same or similar features.

[0018] Figure 1 This is a schematic diagram of the structure of a projection lens provided in the first aspect embodiment of this application;

[0019] Figure 2 This is a schematic diagram of another projection lens provided in the first aspect embodiment of this application;

[0020] Figure 3 This is a schematic diagram of the structure of another projection lens provided in the first aspect embodiment of this application;

[0021] Figure 4 This is a schematic diagram of the structure of another projection lens provided in the first aspect of this application.

[0022] Explanation of reference numerals in the attached figures:

[0023] G1, First lens group; S, Aperture stop; G2, Second lens group; P, Prism; CG, Protective glass; DMD, Digital microlens device; SCR, Projection screen;

[0024] 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. Detailed Implementation

[0025] The features and exemplary embodiments of various aspects of this application will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a comprehensive understanding of this application. However, it will be apparent to those skilled in the art that this application can be implemented without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of this application by illustrating examples. In the accompanying drawings and the following description, at least some well-known structures and techniques are not shown to avoid unnecessarily obscuring the application; and, for clarity, the dimensions of some structures may be exaggerated. Furthermore, the features, structures, or characteristics described below can be combined in any suitable manner in one or more embodiments.

[0026] In the description of this application, it should be noted that, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," etc., indicating orientation or positional relationships are only for the convenience of describing this application 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 on this application. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, 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, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0027] The directional terms appearing in the following description refer to the directions shown in the figures and are not intended to limit the specific structure of the embodiments of this application. It should also be noted in the description of this application that, unless otherwise explicitly specified and limited, the terms "installation" and "connection" 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 direct connection or an indirect connection. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0028] As projectors are increasingly used across various fields, the projection lens determines the image quality, and its design is constantly being improved and optimized. Currently, there are greater demands for smaller projector sizes, requiring more compact and smaller projection lenses. This presents certain challenges to lens performance, necessitating both small size and consistent performance, as well as cost reduction.

[0029] This application is proposed to solve the aforementioned technical problems. To better understand this application, the following is combined with... Figures 1 to 4 The projection lens, projection system, and projection device of the present application are described in detail.

[0030] The projection lens in this application embodiment can be a projection lens of a projector. Optionally, the projection lens can be a projection lens of a laser projector. Laser projectors have the characteristics of high image contrast, clear imaging, vivid colors, and higher brightness. Optionally, the projection lens in this application embodiment can also be applied to LED (Light Emitting Diode) projectors, LCD (Liquid Crystal Display) projectors, etc. The projection lens in this application embodiment is not limited to a projection lens of a projector; if other devices use the projection lens provided in this application, they should also fall within the protection scope of this application.

[0031] The projection lens of this application embodiment can be applied to a fixed-focus projection lens of a projector. The fixed-focus projection lens also includes a prism P, a protective glass CG, and a digital micromirror device (DMD) chip. The first lens group G1, the aperture S, the second lens group G2, the prism P, the protective glass CG, and the digital micromirror device DMD are arranged along the optical axis from the magnification side to the reduction side. During projection, light enters the projection lens from the image plane side of the DMD via the prism P, and finally exits the projection lens to the projection screen SCR (Screen), thus obtaining the projection imaging effect. For example, the projection lens can be applied to an in-vehicle projection system or an in-vehicle projection device.

[0032] Please refer to the following: Figure 1 , Figure 1 This is a schematic diagram of the structure of a projection lens provided in the first aspect of this application.

[0033] like Figure 1 As shown, an embodiment of the first aspect of this application provides a projection lens, which includes, along the optical axis from the magnification side to the reduction side, a first lens group G1 with negative optical power, an aperture stop S, and a second lens group G2 with positive optical power; the first lens group G1 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5 arranged sequentially along the optical axis from the magnification side to the reduction side, wherein the first lens L1 has negative refractive power, the second lens L2 has positive refractive power, the third lens L3 has negative refractive power, and the fourth lens L4 has positive refractive power. The first lens has negative refractive power, while the fifth lens L5 has positive refractive power. The second lens group G2 includes a sixth lens L6, a seventh lens L7, an eighth lens L8, a ninth lens L9, and a tenth lens L10 arranged sequentially along the optical axis from the magnification side to the reduction side. The sixth lens L6 has positive refractive power, the seventh lens L7 has negative refractive power, the eighth lens L8 has positive refractive power, the ninth lens L9 has positive refractive power, and the tenth lens L10 has positive refractive power. The focal length of the projection lens is EFL, the aperture number of the projection lens is Fno, and the outer diameter of the largest lens in the projection lens is L. MAX The projection lens must satisfy at least one of the following conditions: 8mm ≤ L MAX / Fno≤30mm; 2mm≤EFL / Fno≤16mm; The lenses of the projection lenses are all all-glass spherical lenses.

[0034] In this embodiment, the magnifying side refers to the side of the projection lens that is closer to the SCR screen when the projection lens is applied to the projection system or projection device, and the shrinking side refers to the side of the projection lens that is closer to the DMD chip.

[0035] Optionally, the projection lens satisfies the following relationship: 8mm ≤ L MAX / Fno≤30mm; 2mm≤EFL / Fno≤16mm; The lenses of the projection lenses are all all-glass spherical lenses.

[0036] The outer diameter of a lens can be understood as the length of the outer diameter of a circular object, that is, the longest straight-line distance from one edge of the lens to the other. It can also be understood as the diameter of the lens itself.

[0037] For example, L MAX The / Fno ratio can be 30mm, 28mm, 26mm, 24mm, 20mm, 18mm, 16mm, 12mm, 8mm, etc. Of course, L... MAX The ratio / Fno can also be any combination of the above values. Optionally, the largest lens in the projection lens can be the first lens L1.

[0038] For example, the EFL / Fno ratio can be 16mm, 15mm, 14mm, 12mm, 10mm, 8mm, 6mm, 4mm, 2mm, etc. Of course, the EFL / Fno ratio can also be any combination of the above values.

[0039] Optionally, the aperture stop S is a variable aperture stop, whose opening diameter can be continuously adjusted. By adjusting the aperture size of the aperture stop S, the brightness of the projection lens can be changed to achieve different applications. For example, when high brightness is required, the aperture of the aperture stop S can be adjusted to the maximum, and when in a darker environment, the aperture of the aperture stop S can be reduced. Optionally, the air gap T1 between the aperture stop S and the sixth lens L6 is greater than 4mm, which can effectively ensure the space requirements of the variable aperture stop structure.

[0040] The Fno parameter represents the light-gathering capability of a lens. Fno = focal length (EFL) of the projection lens / aperture diameter. With the focal length remaining constant, a larger aperture diameter results in a smaller Fno value, stronger light-gathering capability, and higher brightness. In this embodiment, the projection lens can increase the relative aperture of the stop S to achieve a large aperture, increasing light transmission and improving brightness.

[0041] An all-glass spherical lens is a lens whose front and back surfaces are both spherical, or one surface is spherical and the other is flat, and the entire lens is made of glass. Since the radius of curvature of a spherical lens is the same in all directions, its refractive power is also equal.

[0042] In this embodiment, the first lens group G1, the aperture S, and the second lens group G2 are arranged sequentially from the magnifying side to the reducing side along the optical axis. During projection, light rays from the light source pass sequentially through the second lens group G2, the aperture S, and the first lens group G1 from the image plane side, and are finally projected onto the projection screen SCR. The projection lens includes at least ten lenses. By reasonably setting the positive and negative refractive powers of each lens in the first lens group G1 and the second lens group G2, the structure of the projection lens is made precise, thereby achieving the goals of low cost, compactness, and small size.

[0043] In the projection lens of this application embodiment, the projection lens includes a first lens group G1, an aperture S and a second lens group G2. The aperture S can be used to gather the light from the front and back, which is beneficial to shorten the total length of the projection lens.

[0044] The first lens group G1 collects light and corrects distortion and other off-axis aberrations. The second lens group G2 controls the image-side telecentric angle and corrects chromatic aberration and other off-axis aberrations. The first lens group G1 provides distortion correction, which helps to increase the system's field of view. It effectively corrects off-axis aberrations such as distortion, coma, field curvature, and astigmatism, ensuring a relatively smooth angle of incidence between the light and the lens surface, providing a large field of view without producing large higher-order aberrations. By rationally planning the refractive power of each lens, a smooth light transition is ensured, contributing to the stability of the image.

[0045] By limiting the ratio of the focal length EFL to the aperture number Fno of the projection lens to within [2mm, 16mm], the projection lens can have a large aperture, thereby enabling it to have a larger light passage to receive more light and improve the brightness of the light emitted by the projection lens, thus enhancing the performance of the projection lens.

[0046] By limiting the outer diameter L of the largest lens in the projection lens MAX The ratio of L to the aperture number (Fno) is within [8mm, 30mm]. MAX Under constant conditions, a projection lens with a larger aperture can improve the performance of the projection lens.

[0047] When Fno is within a certain range, the outer diameter of the maximum lens is also correspondingly limited, thereby enabling the small-size design of small projection lenses to reduce space occupation. Using all-glass spherical lenses for the projection lens effectively reduces the cost and manufacturing difficulty, improving its applicability. In summary, the embodiments of this application can improve the performance of projection lenses.

[0048] It should be noted that, in the embodiments of this application, some of the all-glass spherical lenses can be replaced with other types of lenses. Optionally, the first lens L1 can be replaced with a plastic aspherical lens. Optionally, one or more of the ninth lens L9, tenth lens L10, and twelfth lens L12 can also be replaced with glass aspherical lenses. This embodiment can also reduce the cost and manufacturing difficulty of the projection lens.

[0049] In the projection lens of this application embodiment, the MTF (Modulation Transfer Function) performance can be improved by setting the parameters of each lens, so that the lens has good imaging quality and at the same time reduces system distortion.

[0050] When the radius of curvature of the magnifying side of a lens is positive, the magnifying side is convex; otherwise, it is concave. When the radius of curvature of the reducing side of a lens is negative, the reducing side is convex; otherwise, it is concave. When the radius of curvature of the magnifying side of a lens is ±∞, the magnifying side is flat. When the radius of curvature of the reducing side of a lens is ±∞, the reducing side is flat.

[0051] In some embodiments, the first lens group G1 further includes an eleventh lens L11, which is disposed between the second lens L2 and the third lens L3. The eleventh lens L11 has negative refractive power or positive refractive power. By reasonably setting the curvature and thickness of the eleventh lens L11, off-axis aberrations and system distortions can be effectively corrected, thereby improving MTF performance.

[0052] Specifically, the eleventh lens L11 can be either a positive meniscus lens or a negative meniscus lens. The magnifying side of the eleventh lens L11 is convex, and the reducing side is concave. The radius of curvature of the surface of the eleventh lens L11 near the magnifying side can be set to 10mm to 40mm, and the radius of curvature of the surface of the eleventh lens L11 near the reducing side can be set to 8mm to 80mm.

[0053] In some embodiments, the second lens group G2 further includes a twelfth lens L12, which is disposed between the eighth lens L8 and the ninth lens L9, and has positive refractive power. By properly setting the curvature and thickness of the twelfth lens L12, off-axis aberrations and system distortions can be effectively corrected, thereby improving MTF performance.

[0054] Specifically, the twelfth lens L12 can be a meniscus lens. The magnifying side of the twelfth lens L12 is concave, the reducing side of the twelfth lens L12 is convex, the radius of curvature of the surface of the twelfth lens L12 near the magnifying side is -40mm to -180mm, and the radius of curvature of the surface of the twelfth lens L12 near the reducing side is -20mm to -40mm.

[0055] In some embodiments, the fourth lens L4 and the fifth lens L5 form a cemented doublet with positive refractive power.

[0056] In some embodiments, the sixth lens L6, the seventh lens L7, and the eighth lens L8 constitute a triplet lens group with negative refractive power.

[0057] A cemented doublet lens group is a lens group formed by cementing two lenses together, while a cemented triplet lens group is a lens group formed by cementing three lenses together, with the cemented surfaces of adjacent lenses touching each other.

[0058] In these embodiments, by cementing two lenses, the fourth lens L4 and the fifth lens L5, and cementing three lenses, the sixth lens L6, the seventh lens L7, and the eighth lens L8, together to form a cemented lens, it is beneficial to correct chromatic aberration and reduce the air gap between the lenses, thereby compressing the overall optical length of the system.

[0059] In addition, in the embodiments of this application, only one set of cemented doublet lens group and one set of cemented triplet lens group can be set, thereby reducing the cost of the projection lens.

[0060] In some embodiments, the fourth lens L4 is a biconcave negative lens, and the fifth lens L5 is a biconvex positive lens. The magnifying side and the reducing side of the fourth lens L4 are both concave. The magnifying side and the reducing side of the fifth lens L5 are both convex. The radius of curvature of the surface of the fourth lens L4 near the magnifying side is -15mm to -48mm, and the radius of curvature of the surface of the fourth lens L4 near the reducing side is 5mm to 20mm. The radius of curvature of the surface of the fifth lens L5 near the magnifying side is 5mm to 20mm, and the radius of curvature of the surface of the fifth lens L5 near the reducing side is -20mm to -80mm.

[0061] In some embodiments, the sixth lens L6 is a biconvex positive lens or a meniscus positive lens, the seventh lens L7 is a biconcave negative lens, and the eighth lens L8 is a biconvex positive lens. The magnifying side of the sixth lens L6 can be concave or convex; the reducing side of the sixth lens L6 is convex; when the magnifying side of the sixth lens L6 is concave, the sixth lens L6 is a meniscus positive lens; when the magnifying side of the sixth lens L6 is convex, the sixth lens L6 is a biconvex positive lens. The magnifying side of the seventh lens L7 is concave, and the reducing side of the seventh lens L7 is also concave. The magnifying side of the eighth lens L8 is convex, and the reducing side of the eighth lens L8 is also convex. This application embodiment uses the sixth lens L6 as a meniscus positive lens as an example. The radius of curvature of the surface of the sixth lens L6 near the magnifying side is -15mm to -40mm, and the radius of curvature of the surface of the sixth lens L6 near the reducing side is -7mm to -30mm. The radius of curvature of the surface of the seventh lens L7 near the magnifying side is -7mm to -30mm, and the radius of curvature of the surface of the seventh lens L7 near the reducing side is 25mm to 50mm. The radius of curvature of the surface of the eighth lens L8 near the magnifying side is 25mm to 50mm, and the radius of curvature of the surface of the eighth lens L8 near the reducing side is -10mm to -40mm.

[0062] In these embodiments, by reasonably setting the concave and convex shapes of each lens surface, the optical lens can have smaller aberrations, better light utilization, and higher resolution.

[0063] In some embodiments, the first lens L1 can be a meniscus negative lens, with the radius of curvature of the surface of the first lens L1 near the magnification side being 30mm to 60mm, and the radius of curvature of the surface of the first lens L1 near the reduction side being 10mm to 35mm. The second lens L2 can be a meniscus positive lens, with the radius of curvature of the surface of the second lens L2 near the magnification side being 15mm to 40mm, and the radius of curvature of the surface of the second lens L2 near the reduction side being 60mm to infinity. The third lens L3 can be a meniscus negative lens, with the radius of curvature of the surface of the third lens L3 near the magnification side being 10mm to 50mm, and the radius of curvature of the surface of the third lens L3 near the reduction side being 5mm to 20mm. The ninth lens L9 can be a biconvex positive lens, with the radius of curvature of the surface of the ninth lens L9 near the magnification side being 150mm to infinity, and the radius of curvature of the surface of the ninth lens L9 near the reduction side being -80mm to -20mm. The tenth lens L10 can be a biconvex positive lens. The radius of curvature of the surface of the tenth lens L10 near the magnification side is 15mm to 60mm, and the radius of curvature of the surface of the tenth lens L10 near the reduction side is -120mm to -40mm.

[0064] In some embodiments, the absolute value of the difference between the refractive index of the fourth lens L4 and the refractive index of the fifth lens L5 is greater than 0.2.

[0065] In some embodiments, the absolute value of the refractive index difference between any two adjacent lenses in the sixth lens L6, the seventh lens L7, and the eighth lens L8 is greater than 0.2.

[0066] In these embodiments, the combination of refractive power and refractive index of multiple lenses in the cemented lens group can effectively correct system chromatic aberration, and the cancellation of positive and negative spherical aberrations on the cemented surface can achieve the overall spherical aberration correction effect of the projection lens, thereby ensuring both image quality and simple structure of the projection lens.

[0067] In some embodiments, the back focal length of the projection lens is BFL, the total optical length of the projection lens is TTL, and the image plane height of the projection lens is H, and at least one of the following relationships is satisfied: 0.2≤BFL / EFL≤3; BFL / TTL≥0.1; 5≤TTL / H≤30; 1≤EFL / H≤3.

[0068] In this embodiment, the back focal length of the projection lens can also be called the back focal length; the focal length of the projection lens can also be called the effective focal length. Optionally, the total optical length of the projection lens is TTL, which is the axial distance along the optical axis between the magnifying side of the first lens L1 and the DMD chip. The back focal length of the projection lens refers to the distance along the optical axis between the reducing side of the lens closest to the DMD chip and the DMD chip. Optionally, the back focal length of the projection lens is equal to the distance along the optical axis between the reducing side of the tenth lens L10 and the DMD chip.

[0069] Optionally, the projection lens satisfies the following relationships: 0.2≤BFL / EFL≤3; BFL / TTL≥0.1; 5≤TTL / H≤30; 1≤EFL / H≤3. By possessing a long back focus while also having a short lens length, the projection device using this lens can be miniaturized.

[0070] For example, the BFL / EFL ratio can be 3, 2.8, 2.6, 2.2, 2, 1.8, 1.4, 1, 0.6, or 0.2, etc. Of course, the BFL / EFL ratio can also be any combination of the above values. The BFL / TTL ratio can be 0.1, 0.2, 0.3, 0.4, 0.5, etc. The TTL / H ratio can be 5, 10, 15, 20, 25, 30, etc. The EFL / H ratio can be 1, 1.2, 1.6, 1.8, 2, 2.4, 2.8, 3, etc.

[0071] In some embodiments, the focal length of the first lens group G1 is EFL. ZOOM1 The focal length of the second lens group G2 is EFL. ZOOM2 And it satisfies the following relationship: -100.0 < EFL ZOOM1 / EFL < -20.0; 0.3 < EFL ZOOM2 / EFL < 2.6.

[0072] For example, EFL ZOOM1 The / EFL ratio can be -95, -90, -80, -70, -60, -50, -40, -30, or -25, etc. Of course, EFL... ZOOM1 The / EFL ratio can also be any combination of the above values.

[0073] For example, EFL ZOOM2 The ratio of / EFL can be 2.5, 2.4, 2.3, 2.0, 1.8, 1.6, 1.5, 1.2, 1.0, 0.8, 0.5, or 0.4, etc. Of course, EFL... ZOOM2 The / EFL ratio can also be any combination of the above values.

[0074] In some embodiments, the projection lens satisfies the following relationship: 9mm≤EFL≤20mm.

[0075] For example, the focal length (EFL) of the projection lens can be 9mm, 9.5mm, 10mm, 11mm, 12mm, 13mm, 15mm, 16mm, 18mm, 19mm, or 20mm, etc. Of course, the focal length (EFL) of the projection lens can also be any combination of the above values.

[0076] In some embodiments, the projection lens satisfies the following relationship: TTL≤180mm.

[0077] For example, the total optical length (TTL) of the projection lens can be 180mm, 179mm, 178mm, 177mm, 176mm, 175mm, 174mm, 173mm, 172mm, 171mm, or 170mm, etc. Of course, the total optical length (TTL) of the projection lens can also be any combination of the above values.

[0078] In some embodiments, the projection lens satisfies the following relationship: BFL ≥ 20mm. BFL can be the distance from the tenth lens L10 to the DMD in the projection lens. The space between the tenth lens L10 and the DMD can be used to place the prism P, protective glass CG, etc.

[0079] For example, the back focal length (BFL) of the projection lens can be 20mm, 25mm, 30mm, 35mm, 40mm, 45mm, 50mm, 55mm, 60mm, 65mm, or 70mm, etc. Of course, the back focal length (BFL) of the projection lens can also be any combination of the above values.

[0080] In some embodiments, the projection lens satisfies the following relationship: 1.5 ≤ Fno ≤ 3. The smaller the Fno value, the stronger the light transmission capability of the lens and the higher the brightness. The projection lens in this embodiment can increase the relative aperture of the aperture to achieve a large aperture, increase the amount of light transmitted, and improve the brightness.

[0081] For example, the aperture number Fno of the projection lens can be 1.5, 1.6, 1.8, 2.2, 2.4, 2.6, 2.8, or 3.0, etc. Of course, the aperture number Fno of the projection lens can also be any combination of the above values.

[0082] In some embodiments, the diameter of each lens is no greater than 60mm. This facilitates the miniaturization of the projection lens.

[0083] For example, the diameter of each lens can be 60mm, 55mm, 45mm, 40mm, 38mm, 36mm, 35mm, 34.6mm, 34.4mm, 34.2mm, or 34.0mm, etc. Of course, the diameter of each lens can also be any combination of the above values.

[0084] In some embodiments, the first lens group G1 includes at least two lenses with a refractive index greater than 1.8. This can correct lens distortion and astigmatism, and also correct the sine difference of the lens to a certain extent, thereby further improving image quality. For example, the first lens group G1 may include 2, 3, 4, 5, or 6 lenses with a refractive index greater than 1.8.

[0085] In some embodiments, the second lens group G2 includes at least two lenses with a refractive index greater than 1.8. This can correct lens distortion and astigmatism, and also correct the sine difference of the lens to a certain extent, thereby further improving image quality. For example, the second lens group G2 may include 2, 3, 4, 5, or 6 lenses with a refractive index greater than 1.8.

[0086] In some embodiments, the second lens group G2 includes X lenses whose refractive index temperature coefficient Dn / Dt is negatively proportional to their focal length EFFL-n, i.e., (Dn / Dt) / EFFL-n < 0, where Dn / Dt is the refractive index temperature coefficient of the lens, and EFFL-n is the focal length of the lens. Furthermore, the following relationship must be satisfied: 2 ≤ X ≤ 4. A lens with positive refractive power and a negative refractive index temperature coefficient Dn / Dt can compensate for thermal defocusing of the entire projection lens. A lens with negative refractive power and a positive refractive index temperature coefficient Dn / Dt can also compensate for thermal defocusing of the entire projection lens.

[0087] Optionally, X can be 2, 3, or 4. For example, the ratio of the refractive index temperature coefficient to the focal length of the sixth lens L6 can be negative; the ratio of the refractive index temperature coefficient to the focal length of the eighth lens L8 can be negative; and the ratio of the refractive index temperature coefficient to the focal length of the tenth lens L10 can be negative.

[0088] In these embodiments, the projection lens that meets the above conditions can effectively compensate for thermal defocusing, so that the projection lens does not have a significant impact on image quality within a certain temperature range.

[0089] The projection lens provided in this application has a precise structure, enabling a low-cost, compact design. The lens is small in size, with significant limitations on its overall length and lens aperture to minimize space occupation. The compact structural design allows for miniaturization of the projection lens. It satisfies the requirements of high resolution while maintaining a compact structure and controllable cost. When applied to automotive applications, it provides greater design freedom to avoid interference issues caused by interior trim components. This application is based on optical imaging principles, using optical design software to repeatedly optimize the curvature radius, material, thickness, air gap, and two cemented lenses of the projection lens. This achieves the goals of low aberration, high resolution, long back focal length, small overall length, simple structure, high manufacturability, and ease of mass production.

[0090] A second aspect of this application also provides a projection system, which includes a projection lens according to any embodiment of the first aspect described above. Since the projection system of this application includes a projection lens according to any embodiment of the first aspect described above, it also possesses the aforementioned advantages of the projection lens of this application.

[0091] A third aspect of this application also provides a projection device, which includes a projection lens of any embodiment of the first aspect or a projection system of the second aspect. Since the projection device of this application includes a projection lens of any embodiment of the first aspect or a projection system of the second aspect, it also possesses the aforementioned advantages of the projection lens of this application.

[0092] The technical solution of this application will be further described below with reference to the embodiments.

[0093] Example 1

[0094] Please refer to the following: Figure 1 The projection lens in Embodiment 1, from the magnifying side to the reducing side, includes, in sequence, a first lens L1, a second lens L2, an eleventh lens L11, a third lens L3, a fourth lens L4, a fifth lens L5, an aperture S, a sixth lens L6, a seventh lens L7, an eighth lens L8, a twelfth lens L12, a ninth lens L9, a tenth lens L10, a prism P, and a protective glass CG. The refractive powers of the twelve lenses, from the magnifying side to the reducing side, are, in sequence, negative, positive, negative, negative, negative, positive, positive, negative, positive, positive, positive, positive.

[0095] The relevant parameters of each component are shown in Table 1.

[0096] Table 1

[0097]

[0098]

[0099] Among them, surfaces 1 to 26 are arranged sequentially from the enlarged side to the reduced side.

[0100] Example 1 provides a lens with a maximum aperture of 27.6mm, a back focal length (BFL) of 23mm, and an L... MAX This large-aperture projection lens features a 13.8mm f / no and an 8mm EFL f / no. Its precise structure enables a low-cost, compact imaging lens. Based on optical imaging principles, this application utilizes optical design software to repeatedly optimize the curvature radius, material, thickness, air gap, and two cemented lenses of the projection lens. This results in minimal aberrations, high resolution, a long back focal length, a small overall length, a simple structure, high manufacturability, and ease of mass production.

[0101] Example 2

[0102] Please refer to the following: Figure 2 The projection lens in Embodiment 2, from the magnifying side to the reducing side, includes, in sequence, a first lens L1, a second lens L2, an eleventh lens L11, a third lens L3, a fourth lens L4, a fifth lens L5, an aperture S, a sixth lens L6, a seventh lens L7, an eighth lens L8, a twelfth lens L12, a ninth lens L9, a tenth lens L10, a prism P, and a protective glass CG. The refractive powers of the twelve lenses, from the magnifying side to the reducing side, are, in sequence, negative, positive, negative, negative, negative, positive, positive, negative, positive, positive, positive, positive.

[0103] The relevant parameters of each component are shown in Table 2.

[0104] Table 2

[0105]

[0106] Among them, surfaces 1 to 26 are arranged sequentially from the enlarged side to the reduced side.

[0107] Example 2 provides a lens with a maximum aperture of 33.4mm, a back focal length (BFL) of 24mm, and an L... MAX This large-aperture projection lens features a 16.7mm f / no and a 7.5mm EFL f / no. Its precise structure enables a low-cost, compact imaging lens. Based on optical imaging principles, this application utilizes optical design software to repeatedly optimize the curvature radius, material, thickness, air gap, and two cemented lenses of the projection lens. This results in minimal aberrations, high resolution, a long back focal length, a small overall length, a simple structure, high manufacturability, and ease of mass production.

[0108] Example 3

[0109] Please refer to the following: Figure 3The projection lens in Embodiment 3, from the magnifying side to the reducing side, includes, in sequence, a first lens L1, a second lens L2, an eleventh lens L11, a third lens L3, a fourth lens L4, a fifth lens L5, an aperture S, a sixth lens L6, a seventh lens L7, an eighth lens L8, a twelfth lens L12, a ninth lens L9, a tenth lens L10, a prism P, and a protective glass CG. The refractive powers of the twelve lenses, from the magnifying side to the reducing side, are, in sequence, negative, positive, positive, negative, negative, positive, positive, negative, positive, positive, positive, positive.

[0110] The difference between Example 3 and Examples 1 and 2 is that the eleventh lens L11 in Examples 1 and 2 is a meniscus negative lens, while the eleventh lens L11 in Example 3 is a meniscus positive lens. The specific parameters of the projection lens also differ.

[0111] The relevant parameters of each component are shown in Table 3.

[0112] Table 3

[0113]

[0114]

[0115] Among them, surfaces 1 to 26 are arranged sequentially from the enlarged side to the reduced side.

[0116] Example 3 provides a lens with a maximum aperture of 33.4mm, a back focal length (BFL) of 22mm, and an L... MAX This large-aperture projection lens features a 16.7mm f / no and a 6.7mm EFL f / no. Its precise structure enables a low-cost, compact imaging lens. Based on optical imaging principles, this application utilizes optical design software to repeatedly optimize the curvature radius, material, thickness, air gap, and two cemented lenses of the projection lens. This results in minimal aberrations, high resolution, a long back focal length, a small overall length, a simple structure, high manufacturability, and ease of mass production.

[0117] Example 4

[0118] Please refer to the following: Figure 4 The projection lens in Embodiment 4, from the magnification side to the reduction side, includes a first lens L1, a second lens L2, an eleventh lens L11, a third lens L3, a fourth lens L4, a fifth lens L5, an aperture S, a sixth lens L6, a seventh lens L7, an eighth lens L8, a ninth lens L9, a tenth lens L10, a prism P, and a protective glass CG.

[0119] The difference between Example 4 and Examples 1-3 is that Examples 1-3 have a 12-lens structure, while Example 4 has an 11-lens structure. Furthermore, from the magnifying side to the reducing side, the refractive power of the lenses is negative, positive, negative, negative, negative, positive, positive, negative, positive, positive, positive, positive. The fourth lens L4 and the fifth lens L5 can be unbonded. The specific parameters of the projection lens also differ.

[0120] This application may be implemented in other specific forms without departing from its spirit and essential characteristics. For example, the algorithm described in a particular embodiment may be modified without departing from the basic spirit of this application. Therefore, the present embodiments are to be regarded as exemplary rather than limiting in all respects, and the scope of this application is defined by the appended claims rather than the foregoing description, and all changes falling within the meaning and scope of the claims and their equivalents are thus included within the scope of this application.

Claims

1. A projection lens, characterized in that, Along the optical axis from the magnifying side to the reducing side, it includes a first lens group with negative optical power, an aperture, and a second lens group with positive optical power in sequence. The first lens group includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens arranged sequentially along the optical axis from the magnification side to the reduction side. The first lens has negative refractive power, the second lens has positive refractive power, the third lens has negative refractive power, the fourth lens has negative refractive power, and the fifth lens has positive refractive power. The second lens group includes a sixth lens, a seventh lens, an eighth lens, a ninth lens, and a tenth lens arranged sequentially along the optical axis from the magnification side to the reduction side. The sixth lens has positive refractive power, the seventh lens has negative refractive power, the eighth lens has positive refractive power, the ninth lens has positive refractive power, and the tenth lens has positive refractive power. The focal length of the projection lens is EFL, the aperture number of the projection lens is Fno, and the outer diameter of the largest lens in the projection lens is L. MAX The projection lens satisfies at least one of the following conditions: 8mm≤L MAX / Fno≤30mm; 2mm≤EFL / Fno≤16mm; All projection lenses are all-glass spherical lenses.

2. The projection lens according to claim 1, characterized in that, The first lens group further includes an eleventh lens, which is disposed between the second lens and the third lens. The eleventh lens has negative refractive power, or, the eleventh lens has positive refractive power; and / or, The second lens group also includes a twelfth lens, which is disposed between the eighth lens and the ninth lens, and the twelfth lens has positive diopter.

3. The projection lens according to claim 2, characterized in that, The first lens is a plastic aspherical lens; and / or, At least one of the ninth lens, the tenth lens, and the twelfth lens is a glass aspherical lens.

4. The projection lens according to claim 1, characterized in that, The fourth lens and the fifth lens form a cemented doublet with positive refractive power; and / or, The sixth lens, the seventh lens, and the eighth lens constitute a triplex lens group with negative refractive power.

5. The projection lens according to claim 4, characterized in that, The fourth lens is a biconcave negative lens, and the fifth lens is a biconvex positive lens; and / or, The sixth lens is a biconvex positive lens or a meniscus positive lens, the seventh lens is a biconcave negative lens, and the eighth lens is a biconvex positive lens.

6. The projection lens according to claim 4, characterized in that, The absolute value of the difference between the refractive index of the fourth lens and the refractive index of the fifth lens is greater than 0.2; and / or, In the sixth lens, the seventh lens, and the eighth lens, the absolute value of the refractive index difference between any two adjacent lenses is greater than 0.

2.

7. The projection lens according to claim 1, characterized in that, The projection lens has a back focal length of BFL, a total optical length of TTL, and an image plane height of H, and satisfies at least one of the following relationships: 0.2≤BFL / EFL≤3; BFL / TTL≥0.1; 5≤TTL / H≤30; 1≤EFL / H≤3.

8. The projection lens according to any one of claims 1 to 7, characterized in that, The focal length of the first lens group is EFL. ZOOM1 The focal length of the second lens group is EFL. ZOOM2 And satisfy the following relation: -100.0<EFL ZOOM1 / EFL<-20.0; 0.3<EFL ZOOM2 / EFL<2.6。 9. The projection lens according to any one of claims 1 to 7, characterized in that, The projection lens has a back focal length of BFL, an optical total length of TTL, and satisfies at least one of the following relationships: 9mm≤EFL≤20mm; TTL≤180mm; BFL ≥ 20mm; 1.5≤Fno≤3; The diameter of each lens shall not exceed 60mm.

10. The projection lens according to any one of claims 1 to 7, characterized in that, The first lens group includes at least two lenses with a refractive index greater than 1.8; and / or, The second lens group includes at least two lenses with a refractive index greater than 1.8; and / or, The second lens group includes lenses with a negative ratio of refractive index temperature coefficient to focal length, and satisfies the following relationship: 2≤X≤4.

11. A projection system, characterized in that, Includes the projection lens according to any one of claims 1 to 10.

12. A projection device, characterized in that, Includes the projection lens of any one of claims 1 to 10 or the projection system of claim 11.

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