projection lens

Abstract

The application discloses a projection lens, which comprises a four-piece imaging lens group and a plurality of isolation pieces. The four-piece imaging lens group comprises a first lens, a second lens, a third lens and a fourth lens arranged in sequence along an optical axis from an imaging side to an image source side. The plurality of isolation pieces comprises a first isolation piece arranged on an image source side surface of the first lens, a second isolation piece arranged on an image source side surface of the second lens, and a third isolation piece arranged on an image source side surface of the third lens. The radius of curvature R4 of the image source side surface of the second lens, the radius of curvature R5 of the imaging side surface of the third lens, and the interval EP23 of the second isolation piece and the third isolation piece along the optical axis satisfy 9.0<|(R4-R5) / EP23|<28.0. The radius of curvature R6 of the image source side surface of the third lens, the radius of curvature R7 of the imaging side surface of the fourth lens, the inner diameter d3s of the imaging side surface of the third isolation piece, and the inner diameter d3m of the image source side surface of the third isolation piece satisfy 2.0<R6 / d3s+R7 / d3m<6.0.

Description

Technical Field

[0001] This application relates to the field of optical devices, specifically to a four-element projection lens. Background Technology

[0002] With the rapid development of technology, the applications of projection lenses are becoming more diversified. The diverse application environments of projection lenses force them to maintain stable performance and image quality in various application environments.

[0003] In the conventional design process of four-element projection lenses, in order to achieve good imaging quality and high-quality images, it is necessary not only to avoid stray light but also to improve the assembly stability of the lenses. Therefore, how to set the arrangement relationship between each lens and the isolator, as well as the inner and outer diameters of the isolator, to improve stray light and enhance the assembly stability of the lenses has become an urgent problem to be solved in this field. Summary of the Invention

[0004] This application provides a projection lens that can at least solve or partially solve at least one problem or other problems existing in the prior art.

[0005] One aspect of this application provides a projection lens comprising a lens barrel, a four-element imaging lens group disposed within the lens barrel, and a plurality of isolation members. The four-element imaging lens group includes a first lens, a second lens, a third lens, and a fourth lens arranged sequentially along the optical axis from the imaging side to the image source side. The plurality of isolation members includes a first isolation member, a second isolation member, and a third isolation member. The first isolation member is disposed on and in contact with the image source side surface of the first lens, the second isolation member is disposed on and in contact with the image source side surface of the second lens, and the third isolation member is disposed on... The second lens is located on the image source side surface of the third lens and is in contact with the image source side surface of the third lens; wherein, the radius of curvature R4 of the image source side surface of the second lens, the radius of curvature R5 of the imaging side surface of the third lens, and the spacing EP23 of the second and third isolators along the optical axis satisfy: 9.0 < |(R4-R5) / EP23| < 28.0, and the radius of curvature R6 of the image source side surface of the third lens, the radius of curvature R7 of the imaging side surface of the fourth lens, the inner diameter d3s of the imaging side surface of the third isolator, and the inner diameter d3m of the image source side surface of the third isolator satisfy: 2.0 <R6 / d3s+R7 / d3m<6.0。

[0006] According to an exemplary embodiment of this application, the first lens and the second lens have optical powers that are opposite in sign.

[0007] According to an exemplary embodiment of this application, the entrance pupil diameter EPD of the projection lens, the inner diameter d0s of the imaging side surface of the lens barrel, and the inner diameter d0m of the image source side surface of the lens barrel satisfy: 2.0 <EPD / (d0m-d0s)<5.5。

[0008] According to an exemplary embodiment of this application, the first lens is a glass lens, and the refractive index of the first lens is less than 1.53.

[0009] According to an exemplary embodiment of this application, the inner diameter d1s of the imaging side surface of the first isolator, the inner diameter d2s of the imaging side surface of the second isolator, the refractive index N1 of the first lens and the refractive index N2 of the second lens satisfy: -8.0mm < (d2s-d1s) / (N2-N1) < 5.5mm.

[0010] According to an exemplary embodiment of this application, the effective focal length f1 of the first lens, the effective focal length f2 of the second lens, the effective focal length f3 of the third lens, and the spacing EP23 of the second and third isolators along the optical axis satisfy: -12.0 < (f1 + f2 + f3) / EP23 < -3.5.

[0011] According to an exemplary embodiment of this application, the maximum thickness CP1 of the first isolator, the air gap T12 between the first and second lenses on the optical axis, the maximum thickness CP2 of the second isolator, and the air gap T23 between the second and third lenses on the optical axis satisfy: 0 <CP1 / T12+CP2 / T23<8.0。

[0012] According to an exemplary embodiment of this application, the total effective focal length f of the projection lens, the outer diameter D1m of the image source side surface of the first isolator and the outer diameter D3m of the image source side surface of the third isolator satisfy: 3.5 < |f / (D3m-D1m)| < 20.0.

[0013] According to an exemplary embodiment of this application, the length L of the lens barrel in the direction of the optical axis and the total effective focal length f of the projection lens satisfy: L / f<1.0.

[0014] According to an exemplary embodiment of this application, the radius of curvature R1 of the imaging side surface of the first lens, the radius of curvature R2 of the image source side surface of the first lens, the spacing EP01 of the imaging side surface of the lens barrel and the first isolator along the optical axis and the refractive index N1 of the first lens satisfy: 8.5 < (R1-R2) / (EP01×N1) < 44.5.

[0015] According to an exemplary embodiment of this application, the inner diameter d0s of the imaging side surface of the lens barrel, the spacing EP01 between the imaging side surface of the lens barrel and the first isolator along the optical axis and the center thickness CT1 of the first lens on the optical axis satisfy: 2.0mm < (d0s × CT1) / EP01 < 5.0mm.

[0016] According to an exemplary embodiment of this application, the radius of curvature R5 of the imaging side surface of the third lens, the radius of curvature R7 of the imaging side surface of the fourth lens, and the inner diameter d3s of the imaging side surface of the third isolator satisfy: -16.0 < (R5 + R7) / d3s < 11.5.

[0017] According to an exemplary embodiment of this application, the effective focal length f2 of the second lens, the effective focal length f3 of the third lens, the distance EP12 between the first and second isolators along the optical axis and the distance EP23 between the second and third isolators along the optical axis satisfy: -20.0 < |f3| / EP23 + f2 / EP12 < -6.5.

[0018] According to an exemplary embodiment of this application, the inner diameter d1s of the imaging side surface of the first isolator, the inner diameter d1m of the image source side surface of the first isolator, the radius of curvature R2 of the image source side surface of the first lens, and the radius of curvature R3 of the imaging side surface of the second lens satisfy: -39.5<(d1s×R2) / (d1m×R3)<-8.5.

[0019] This application relates to a four-element projection lens. During image formation, light passes through the image source side of the fourth lens to the imaging side of the first lens and finally forms an image on the projection surface. By controlling the curvature radii of the object or image sides of the second, third, and fourth lenses, the shapes of the three lenses are effectively limited. At the same time, the spacing between the second and third isolators along the optical axis, as well as the inner diameter of the imaging and image source side surfaces of the third isolator, are controlled. This avoids problems such as poor lens forming and affecting surface parameters caused by the optical axis region shapes of the second, third, and fourth lenses approaching the limits of the manufacturing process. It also constrains the edge thickness of the lens near the image source side (such as the third lens) and reasonably sets the inner diameter of the third isolator, so that the lenses on both sides of the third isolator can be well supported. This is beneficial to improving the stability of the projection lens and the yield of the assembly process, enabling the projection lens to obtain good image quality. Attached Figure Description

[0020] 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:

[0021] Figure 1 A schematic diagram of the structure of a projection lens according to this application is shown;

[0022] Figure 2 A schematic diagram of the projection lens of Embodiment 1 according to the first embodiment of this application is shown;

[0023] Figure 3 A schematic diagram of the projection lens of Embodiment 2 according to the first embodiment of this application is shown;

[0024] Figure 4 A schematic diagram of the projection lens of Embodiment 3 according to the first embodiment of this application is shown;

[0025] Figures 5A to 5D The on-axis chromatic aberration curve, astigmatism curve, distortion curve, and magnification chromatic aberration curve of the projection lens according to the first embodiment of this application are shown respectively.

[0026] Figure 6 A schematic diagram of the projection lens of Embodiment 1 according to the second embodiment of this application is shown;

[0027] Figure 7 A schematic diagram of the projection lens of Embodiment 2 according to the second embodiment of this application is shown;

[0028] Figure 8 A schematic diagram of the projection lens of Embodiment 3 according to the second embodiment of this application is shown;

[0029] Figures 9A to 9D The on-axis chromatic aberration curve, astigmatism curve, distortion curve, and magnification chromatic aberration curve of the projection lens according to the second embodiment of this application are shown respectively.

[0030] Figure 10 A schematic diagram of the projection lens of Embodiment 1 according to the third embodiment of this application is shown;

[0031] Figure 11 A schematic diagram of the projection lens of Embodiment 2 according to the third embodiment of this application is shown;

[0032] Figure 12 A schematic diagram of the projection lens of Embodiment 3 according to the third embodiment of this application is shown; and

[0033] Figures 13A to 13D The on-axis chromatic aberration curve, astigmatism curve, distortion curve, and magnification chromatic aberration curve of the projection lens according to the third embodiment of this application are shown respectively. Detailed Implementation

[0034] To better understand this application, various aspects of this application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely illustrative of exemplary embodiments of this application and are not intended to limit the scope of this application in any way. Throughout the specification, the same reference numerals refer to the same elements.

[0035] It should be noted that in this specification, the terms "first," "second," "third," etc., are used only to distinguish one feature from another and do not imply any limitation on the features. Therefore, without departing from the teachings of this application, the first lens discussed below may also be referred to as the second lens or the third lens.

[0036] In the accompanying drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are illustrated by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustrative purposes only and are not drawn strictly to scale.

[0037] In this paper, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the location of the convexity is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the location of the concaveness is not defined, it means that the lens surface is concave at least in the paraxial region. When projection lenses are used in devices such as AR and VR, the surface of each lens closest to the human eye is called the imaging side surface of the lens, and the surface of each lens closest to the image source side is called the image source side surface of the lens.

[0038] It should also be understood that the terms "comprising," "including," "having," "containing," and / or "comprising" as used in this specification indicate the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. Furthermore, when describing embodiments of this application, the word "may" is used to mean "one or more embodiments of this application." And the term "exemplary" is intended to refer to an example or illustration.

[0039] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms (e.g., those defined in common dictionaries) shall be interpreted as having the meaning consistent with their meaning in the context of the relevant art and shall not be interpreted in an idealized or overly formalized sense, unless expressly so specified herein.

[0040] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0041] Figure 1 This document illustrates a structural layout diagram and schematic diagrams of some parameters of a projection lens according to an exemplary embodiment of this application. Those skilled in the art should understand that some parameters frequently used in the field, such as the maximum thickness CP2 of the second separator, are not included. Figure 1 As shown in the image. Figure 1 Only a few parameters of the lens barrel and the insulating member of the projection lens of this application are shown as examples to facilitate a better understanding of this application. Figure 1 As shown, d1s represents the inner diameter of the imaging side surface of the first isolator, d1m represents the inner diameter of the image source side surface of the first isolator, D1m represents the outer diameter of the image source side surface of the first isolator, d2s represents the inner diameter of the imaging side surface of the second isolator, d3s represents the inner diameter of the imaging side surface of the third isolator, d3m represents the inner diameter of the image source side surface of the third isolator, D3m represents the outer diameter of the image source side surface of the third isolator, d0s represents the inner diameter of the imaging side surface of the lens barrel, d0m represents the inner diameter of the image source side surface of the lens barrel, EP01 represents the distance between the imaging side surface of the lens barrel and the first isolator along the optical axis, CP1 represents the maximum thickness of the first isolator, EP12 represents the distance between the first and second isolators along the optical axis, CP2 represents the maximum thickness of the second isolator, EP23 represents the distance between the second and third isolators along the optical axis, and L represents the length of the lens barrel in the direction of the optical axis.

[0042] The features, principles and other aspects of this application are described in detail below.

[0043] like Figures 2 to 4 , Figures 6 to 8 as well as Figures 10 to 12 As shown, a projection lens according to an exemplary embodiment of this application may include a lens barrel and a four-element imaging lens group disposed within the lens barrel. The four-element imaging lens group may include a first lens, a second lens, a third lens, and a fourth lens arranged sequentially along the optical axis from the imaging side to the image source side. An air gap may exist between any two adjacent lenses in the first to fourth lenses.

[0044] The projection lens may also include multiple isolators placed within the lens barrel. These isolators include a first isolator, a second isolator, and a third isolator. The first isolator is disposed on and partially contacts the image source-side surface of the first lens. The second isolator is disposed on and partially contacts the image source-side surface of the second lens. The third isolator is disposed on and partially contacts the image source-side surface of the third lens. Proper use of isolators can effectively mitigate stray light risks, reduce interference with image quality, and thus improve the imaging quality of the projection lens.

[0045] In the example, the radius of curvature R4 of the image source side surface of the second lens, the radius of curvature R5 of the imaging side surface of the third lens, and the interval EP23 between the second spacer and the third spacer along the optical axis may satisfy: 9.0 < |(R4 - R5) / EP23| < 28.0; and the radius of curvature R6 of the image source side surface of the third lens, the radius of curvature R7 of the imaging side surface of the fourth lens, the inner diameter d3s of the imaging side surface of the third spacer, and the inner diameter d3m of the image source side surface of the third spacer may satisfy: 2.0 < R6 / d3s + R7 / d3m < 6.0. The projection lens of the present application is a four-piece projection lens. When the projection lens forms an image, light passes through the image source side of the fourth lens and reaches the imaging side of the first lens and finally forms an image on the projection surface. By controlling the mutual relationship among the radius of curvature of the image source side surface of the second lens, the radius of curvature of the imaging side surface and the image source side surface of the third lens, the radius of curvature of the imaging side surface of the fourth lens, the interval between the second spacer and the third spacer along the optical axis, and the inner diameters of the imaging side surface and the image source side surface of the third spacer, it is possible to effectively limit the shapes of the second lens, the third lens, and the fourth lens while controlling the interval between the second spacer and the third spacer along the optical axis and the inner diameters of the imaging side surface and the image source side surface of the third spacer, avoiding problems such as poor lens molding and affecting surface shape and other parameters caused by the shapes of the optical axis regions of the second lens, the third lens, and the fourth lens approaching the limit process, and constraining the edge thickness of the lens (such as the third lens) close to the image source side in the projection lens and reasonably setting the inner diameter of the third spacer, so that the lenses on both sides of the third spacer can be well abutted against it, which is beneficial to improving the stability of the projection lens and the yield rate of the assembly process, and enabling the projection lens to obtain good imaging quality.

[0046] In an exemplary embodiment, the first lens and the second lens may have different positive and negative optical powers. For example, the first lens may have a positive optical power, and the second lens may have a negative optical power. By controlling the first lens and the second lens to have different positive and negative optical powers, it is possible to effectively constrain the combined optical power of the first lens and the second lens, which is beneficial to reducing the spherical aberration and distortion of the projection lens.

[0047] In an exemplary embodiment, the entrance pupil diameter EPD of the projection lens, the inner diameter d0s of the imaging-side surface of the lens barrel, and the inner diameter d0m of the image-source-side surface of the lens barrel may satisfy: 2.0 < EPD / (d0m - d0s) < 5.5. By controlling the relationship among the entrance pupil diameter of the projection lens, the inner diameter of the imaging-side surface of the lens barrel, and the inner diameter of the image-source-side surface of the lens barrel, it is possible to control the inner diameters of the imaging-side surface and the image-source-side surface of the lens barrel while keeping the entrance pupil diameter of the projection lens within a reasonable range. During the projection process of the projection lens, the phenomenon passing through the entrance pupil diameter becomes proportionally smaller after passing through the image-source-side surface of the lens barrel, then passes through the internal optical structure of the projection lens, and finally passes through the imaging-side surface of the lens barrel and produces a corresponding proportionally reduced phenomenon on the projection surface, effectively ensuring the integrity of the entrance pupil phenomenon and reducing the loss of the projection image.

[0048] In an exemplary embodiment, the first lens may be a glass lens, and the refractive index of the first lens may be less than 1.53. By controlling the first lens to be a glass lens and the refractive index of the first lens to be less than 1.53, it is beneficial to correct the temperature drift of the projection lens and reduce the chromatic aberration of the projection lens.

[0049] In an exemplary embodiment, the inner diameter d1s of the imaging-side surface of the first spacer, the inner diameter d2s of the imaging-side surface of the second spacer, the refractive index N1 of the first lens, and the refractive index N2 of the second lens may satisfy: -8.0 mm < (d2s - d1s) / (N2 - N1) < 5.5 mm. By controlling the relationship among the inner diameter of the imaging-side surface of the first spacer, the inner diameter of the imaging-side surface of the second spacer, the refractive index of the first lens, and the refractive index of the second lens, it is possible to control the refractive indices of the first lens and the second lens while keeping the inner diameters of the imaging-side surfaces of the first spacer and the second spacer within a reasonable range, avoiding problems such as the lens structure being too thin due to too large refractive index and large chromatic aberration of the lens, reducing the molding difficulty of the lens, and improving the assembly yield and imaging quality of the projection lens.

[0050] In an exemplary embodiment, the effective focal length f1 of the first lens, the effective focal length f2 of the second lens, the effective focal length f3 of the third lens, and the interval EP23 between the second spacer and the third spacer along the optical axis may satisfy: -12.0 < (f1 + f2 + f3) / EP23 < -3.5. By controlling the relationship among the effective focal length of the first lens, the effective focal length of the second lens, the effective focal length of the third lens, and the interval between the second spacer and the third spacer along the optical axis, it is possible to control the interval between the second spacer and the third spacer along the optical axis while keeping the effective focal lengths of the first lens, the second lens, and the third lens within a reasonable range, avoiding the problem that the total effective focal length of the projection lens exceeds the overall focusing range due to the excessive effective focal length of the lens, and thus unable to project a clear image on the projection surface. Additionally, the second spacer and the third spacer can block excess light, improving the stray light phenomenon of the projection lens.

[0051] In an exemplary embodiment, the maximum thickness CP1 of the first spacer, the air interval T12 between the first lens and the second lens on the optical axis, the maximum thickness CP2 of the second spacer, and the air interval T23 between the second lens and the third lens on the optical axis may satisfy: 0 < CP1 / T12 + CP2 / T23 < 8.0. By controlling the relationship among the maximum thickness of the first spacer, the air interval between the first lens and the second lens on the optical axis, the maximum thickness of the second spacer, and the air interval between the second lens and the third lens on the optical axis, it is possible to keep the maximum thicknesses of the first spacer and the second spacer within a reasonable range, avoiding the problem of interference during the assembly of the first lens and the second lens due to the过小 thickness of the first spacer, improving the imaging quality and performance of the projection lens. Additionally, it can also avoid the problem of large deformation of the second spacer during the assembly process due to the过小 thickness of the second spacer, improving the yield and imaging quality of the projection lens.

[0052] In an exemplary embodiment, the total effective focal length f of the projection lens, the outer diameter D1m of the image source side surface of the first spacer, and the outer diameter D3m of the image source side surface of the third spacer may satisfy: 3.5 < |f / (D3m - D1m)| < 20.0. By controlling the relationship among the total effective focal length of the projection lens, the outer diameter of the image source side surface of the first spacer, and the outer diameter of the image source side surface of the third spacer, it is possible to control the total effective focal length of the projection lens while keeping the outer diameters of the image source side surfaces of the first spacer and the third spacer within a reasonable range, avoiding the problem of enlarged imaging due to the excessive total effective focal length of the projection lens, thereby reducing the imaged object and lowering the image clarity. Or, avoiding the problem of reduced imaging due to the过小 total effective focal length of the projection lens, thereby causing severe vignetting and reducing the illuminance at the edge of the aberration, affecting the imaging quality of the projection lens.

[0053] In an exemplary embodiment, the length L of the lens barrel along the optical axis and the total effective focal length f of the projection lens can satisfy: L / f < 1.0. By controlling the relationship between the length of the lens barrel along the optical axis and the total effective focal length of the projection lens, the total effective focal length of the projection lens can be constrained while keeping the length of the lens barrel along the optical axis within a reasonable range. This reduces the size of the projection lens and the projection device containing the projection lens, and also avoids the problem of the projection device needing to be far away from the projection surface due to an excessively large total effective focal length of the projection lens.

[0054] In an exemplary embodiment, the radius of curvature R1 of the imaging side surface of the first lens, the radius of curvature R2 of the image source side surface of the first lens, the spacing EP01 of the imaging side surface of the lens barrel and the first isolator along the optical axis, and the refractive index N1 of the first lens can satisfy: 8.5 < (R1-R2) / (EP01×N1) < 44.5. By controlling the relationship between the radius of curvature of the imaging side surface of the first lens, the radius of curvature of the image source side surface of the first lens, the spacing of the imaging side surface of the lens barrel and the first isolator along the optical axis, and the refractive index of the first lens, it is possible to constrain the spacing of the imaging side surface of the lens barrel and the first isolator along the optical axis and the refractive index of the first lens while keeping the radii of curvature of the imaging side surface and the image source side surface of the first lens within a reasonable range. Based on the first lens being a glass lens, this effectively controls the overall structure of the first lens and ensures the edge thickness of the first lens, thereby reducing the processing difficulty of the first lens and improving the production yield of the first lens.

[0055] In an exemplary embodiment, the inner diameter d0s of the imaging side surface of the lens barrel, the distance EP01 between the imaging side surface of the lens barrel and the first isolator along the optical axis, and the center thickness CT1 of the first lens on the optical axis can satisfy: 2.0mm < (d0s × CT1) / EP01 < 5.0mm. By controlling the relationship between the inner diameter of the imaging side surface of the lens barrel, the distance between the imaging side surface of the lens barrel and the first isolator along the optical axis, and the center thickness of the first lens on the optical axis, it is possible to constrain the inner diameter of the imaging side surface of the lens barrel while ensuring that the edge thickness and center thickness of the first lens are within a reasonable range, and to limit the thickness of the first lens supporting the lens barrel within a certain range. At the same time, it can also ensure that the projection surface has a large light-gathering area, avoiding the problem that the light-gathering area is too small due to the inner diameter of the imaging side surface of the lens barrel being too small, which would lead to missing projected images and affect the imaging quality of the projection lens.

[0056] In an exemplary embodiment, the radius of curvature R5 of the imaging side surface of the third lens, the radius of curvature R7 of the imaging side surface of the fourth lens, and the inner diameter d3s of the imaging side surface of the third isolator can satisfy: -16.0 < (R5 + R7) / d3s < 11.5. By controlling the relationship between the radius of curvature of the imaging side surface of the third lens, the radius of curvature of the imaging side surface of the fourth lens, and the inner diameter of the imaging side surface of the third isolator, the inner diameter of the imaging side surface of the third isolator can be limited within a certain range while controlling the curvature of the third and fourth lenses. This avoids problems such as excessive lens center thickness, increased thickness-to-thickness ratio, and molding difficulties caused by excessively convex lenses, and also avoids problems such as excessively concave lenses, insufficient lens center thickness, molding difficulties, and large deformation during assembly, thereby improving the production yield of the projection lens.

[0057] In an exemplary embodiment, the effective focal length f2 of the second lens, the effective focal length f3 of the third lens, the spacing EP12 between the first and second isolators along the optical axis, and the spacing EP23 between the second and third isolators along the optical axis can satisfy: -20.0 < |f3| / EP23 + f2 / EP12 < -6.5. By controlling the relationship between the effective focal lengths of the second and third lenses, the spacing between the first and second isolators along the optical axis, and the spacing between the second and third isolators along the optical axis, it is possible to constrain the edge thickness of the second and third lenses while keeping their effective focal lengths within a reasonable range. This controls the deflection angle of the edge field of view of the second and third lenses, reduces the sensitivity of the projection lens, and improves the assembly stability of the projection lens.

[0058] In an exemplary embodiment, the inner diameter d1s of the imaging side surface of the first isolator, the inner diameter d1m of the image source side surface of the first isolator, the radius of curvature R2 of the image source side surface of the first lens, and the radius of curvature R3 of the imaging side surface of the second lens can satisfy: -39.5 < (d1s × R2) / (d1m × R3) < -8.5. By controlling the relationship between the inner diameter of the imaging side surface of the first isolator, the inner diameter of the image source side surface of the first isolator, the radius of curvature of the image source side surface of the first lens, and the radius of curvature of the imaging side surface of the second lens, the bearing difference between the first lens and the second lens can be guaranteed, thereby ensuring the stability of the assembly of the first lens and the second lens. At the same time, it is also beneficial to control the surface shape of the first lens and the second lens, improve the manufacturability of the first lens and the second lens, and improve the yield of the projection lens.

[0059] In an exemplary embodiment, the projection lens further includes an aperture stop, which can be disposed between the imaging side and the first lens as needed.

[0060] The projection lens according to the above embodiments of this application can employ four lenses and multiple isolators. By rationally allocating the parameters of each lens and each isolator, the difficulty of lens molding can be reduced, the chromatic aberration of the projection lens can be decreased, the stray light phenomenon of the projection lens can be improved, and the assembly yield, assembly stability, imaging quality and performance of the projection lens can be enhanced.

[0061] In embodiments of this application, at least one of the mirror surfaces of the first to fourth lenses is an aspherical mirror surface. An aspherical lens is characterized by a continuously changing curvature from its center to its periphery. Unlike a spherical lens, which has a constant curvature from its center to its periphery, an aspherical lens has superior curvature radius characteristics, offering advantages in improving distortion and astigmatism. By using an aspherical lens, aberrations occurring during imaging can be eliminated as much as possible, thereby improving image quality. Optionally, both the imaging-side surface and the image-source-side surface of each of the first to fourth lenses are aspherical mirror surfaces.

[0062] The projection lens according to an exemplary embodiment of this application is a small-volume optical system with high-definition imaging quality, which can be applied to AR / VR and head-mounted devices.

[0063] However, those skilled in the art should understand that, without departing from the technical solutions claimed in this application, the number of lenses and isolation elements constituting the projection lens can be changed to obtain the various results and advantages described in this specification.

[0064] The following describes in further detail, with reference to the accompanying drawings, specific embodiments of the projection lens applicable to the above-described embodiments.

[0065] First Implementation Method

[0066] The following is for reference Figures 2 to 5D A projection lens according to a first embodiment of this application is described. Figure 2 A schematic diagram of the projection lens 110 according to Embodiment 1 of the first embodiment of this application is shown; Figure 3 A schematic diagram of the projection lens 120 according to Embodiment 2 of the first embodiment of this application is shown; Figure 4 A schematic diagram of the projection lens 130 according to Embodiment 3 of the first embodiment of this application is shown.

[0067] like Figures 2 to 4As shown, projection lenses 110, 120, and 130 each include a lens barrel P0, a four-element imaging lens group housed within the lens barrel P0, and multiple isolators. The four-element imaging lens group, from the imaging side to the image source side, includes, in sequence: a first lens E1, a second lens E2, a third lens E3, and a fourth lens E4. An aperture stop STO can be positioned between the imaging side and the first lens E1 as needed. The multiple isolators include: a first isolator P1, a second isolator P2, and a third isolator P3. The isolators prevent excess light from entering the next lens during the imaging process, while also ensuring better contact between the lens and the lens barrel P0, thus enhancing the structural stability of the projection lens.

[0068] The first lens E1 has positive optical power, with its imaging-side surface S1 being convex and its image-source-side surface S2 being convex. The second lens E2 has negative optical power, with its imaging-side surface S3 being convex and its image-source-side surface S4 being concave. The third lens E3 has negative optical power, with its imaging-side surface S5 being concave and its image-source-side surface S6 being concave. The fourth lens E4 has positive optical power, with its imaging-side surface S7 being convex and its image-source-side surface S8 being concave. The filter has an imaging-side surface S9 (not shown) and an image-source-side surface S10 (not shown). Light from the image-source surface S11 (not shown) passes sequentially through each surface S10 to S1 and is finally projected onto a projection surface (not shown) disposed on the imaging side. When the projection lens is applied to, for example, VR or AR devices, light from the image-source surface passes sequentially through each surface S10 to S1 and can finally be projected onto the human eye for imaging.

[0069] Table 1 shows the basic parameters of the projection lens of the first embodiment, wherein the units of radius of curvature, thickness / distance and focal length are all millimeters (mm).

[0070]

[0071] Table 1

[0072] In this embodiment, the total effective focal length of the projection lens is 5.80 mm, half of the maximum field of view of the projection lens is 15.36°, and the entrance pupil diameter (EPD) of the projection lens is 3.01 mm.

[0073] In the first embodiment, the imaging side surface and the image source side surface of any one of the first lens E1 to the fourth lens E4 are both aspherical, and the surface shape x of each aspherical lens can be defined using, but is not limited to, the following aspherical formula:

[0074]

[0075] Where x is the distance vector from the vertex of the aspherical surface at a height h along the optical axis; c is the paraxial curvature of the aspherical surface, c = 1 / R (i.e., the paraxial curvature c is the reciprocal of the radius of curvature R in Table 1 above); k is the conic coefficient; Ai is the i-th order correction coefficient of the aspherical surface. Table 2 gives the higher-order coefficients A4, A6, A8, A1, and A2 that can be used for each aspherical mirror S1-S8 in the first embodiment. 10 A 12 A 14 and A 16 .

[0076] Face number A4 A6 A8 A10 A12 A14 A16 S1 -2.68E-03 -2.99E-03 1.51E-03 -1.41E-03 4.76E-04 -6.72E-05 -1.83E-05 S2 2.29E-02 -1.23E-02 8.38E-03 -3.60E-03 -2.97E-04 6.57E-04 -1.27E-04 S3 -9.82E-02 4.86E-02 -4.49E-02 6.39E-02 -6.16E-02 2.94E-02 -5.19E-03 S4 -1.46E-01 7.23E-02 -8.71E-02 1.20E-01 -1.08E-01 4.14E-02 -2.31E-03 S5 -2.75E-01 2.55E-01 -6.39E-01 9.76E-01 -9.70E-01 5.32E-01 -1.25E-01 S6 -2.72E-01 4.49E-01 -7.81E-01 8.44E-01 -5.76E-01 2.14E-01 -3.23E-02 S7 -2.08E-01 1.47E-01 2.70E-02 -3.29E-01 3.94E-01 -2.15E-01 4.45E-02 S8 -1.59E-01 7.72E-02 -1.40E-02 -4.76E-02 4.80E-02 -2.00E-02 3.07E-03

[0077] Table 2

[0078] The projection lenses 110, 120, and 130 in Embodiments 1, 2, and 3 of the first embodiment differ in the structural dimensions of their included lens barrels and spacers. Tables 3-1 and 3-2 provide some basic parameters of the lens barrels and spacers of the projection lenses 110, 120, and 130 of the first embodiment, such as d1s, d1m, D1m, d2s, d3s, d3m, D3m, d0s, d0m, EP01, CP1, EP12, CP2, EP23, and L, etc. The basic parameters listed in Tables 3-1 and 3-2 are based on... Figure 1 The measurements were obtained using the annotation method shown, and the units of the basic parameters listed in Tables 3-1 and 3-2 are all millimeters (mm).

[0079] Example / Parameters d1s d1m D1m d2s d3s d3m D3m d0s 1-1 3.173 2.927 4.068 2.116 2.423 2.423 4.588 4.174 1-2 3.211 2.986 4.108 2.116 2.348 2.348 3.450 4.174 1-3 2.597 2.597 4.288 2.116 2.427 2.427 4.588 4.174

[0080] Table 3-1

[0081] Example / Parameters d0m EP01 CP1 EP12 CP2 EP23 L 1-1 4.803 1.222 0.317 0.409 0.018 1.581 4.428 1-2 4.803 1.368 0.337 0.530 0.018 1.516 4.428 1-3 4.803 1.222 0.018 0.545 0.018 1.531 4.428

[0082] Table 3-2

[0083] Figure 5A The on-axis chromatic aberration curves of the projection lenses 110, 120 and 130 of the first embodiment are shown, which represent the deflection of the focal point of light of different wavelengths after passing through the projection lenses 110, 120 and 130. Figure 5B The astigmatism curves of projection lenses 110, 120, and 130 of the first embodiment are shown, which represent the meridional image plane curvature and sagittal image plane curvature corresponding to different field of view angles. Figure 5C The distortion curves of the projection lenses 110, 120 and 130 of the first embodiment are shown, which represent the distortion magnitude values ​​corresponding to different field of view angles. Figure 5D The magnification chromatic aberration curves of the projection lenses 110, 120, and 130 of the first embodiment are shown, representing the deviations in image height on the projection surface after light passes through the lenses. According to... Figures 5A to 5DIt can be seen that the projection lenses 110, 120 and 130 provided in the first embodiment can achieve good imaging quality.

[0084] Second Implementation Method

[0085] The following is for reference Figures 6 to 9D A projection lens according to a second embodiment of this application is described. Figure 6 A schematic diagram of the projection lens 210 according to Embodiment 1 of the second embodiment of this application is shown; Figure 7 A schematic diagram of the projection lens 220 according to Embodiment 2 of the second embodiment of this application is shown; Figure 8 A schematic diagram of the projection lens 230 according to Embodiment 3 of the second embodiment of this application is shown.

[0086] like Figures 6 to 8 As shown, projection lenses 210, 220, and 230 each include a lens barrel P0, a four-element imaging lens group housed within the lens barrel P0, and multiple isolators. The four-element imaging lens group, from the imaging side to the image source side, includes: a first lens E1, a second lens E2, a third lens E3, and a fourth lens E4. An aperture stop STO can be positioned between the imaging side and the first lens E1 as needed. The multiple isolators include: a first isolator P1, a second isolator P2, and a third isolator P3. The isolators prevent excess light from entering the next lens during the imaging process, while also ensuring better contact between the lens and the lens barrel P0, thus enhancing the structural stability of the projection lens.

[0087] The first lens E1 has positive optical power, with its imaging-side surface S1 being convex and its image-source-side surface S2 being convex. The second lens E2 has negative optical power, with its imaging-side surface S3 being convex and its image-source-side surface S4 being concave. The third lens E3 has negative optical power, with its imaging-side surface S5 being concave and its image-source-side surface S6 being concave. The fourth lens E4 has positive optical power, with its imaging-side surface S7 being convex and its image-source-side surface S8 being convex. The filter has an imaging-side surface S9 (not shown) and an image-source-side surface S10 (not shown). Light from the image-source surface S11 (not shown) passes sequentially through each surface S10 to S1 and is finally projected onto the projection surface (not shown) disposed on the imaging side. When the projection lens is applied to, for example, VR or AR devices, light from the image-source surface passes sequentially through each surface S10 to S1 and can finally be projected onto the human eye for imaging.

[0088] Table 4 shows the basic parameters of the projection lens in the second embodiment, where the units for radius of curvature, thickness / distance, and focal length are all millimeters (mm).

[0089]

[0090] Table 4

[0091] In this embodiment, the total effective focal length of the projection lens is 5.50 mm, half of the maximum field of view of the projection lens is 16.10°, and the entrance pupil diameter (EPD) of the projection lens is 3.01 mm.

[0092] In the second embodiment, the imaging-side surface and the image source-side surface of any one of the first lens E1 to the fourth lens E4 are aspherical. Table 5 shows the higher-order coefficients A4, A6, A8, and A6 that can be used for each aspherical mirror S1-S8 in the second embodiment. 10 A 12 A 14 and A 16 .

[0093] Face number A4 A6 A8 A10 A12 A14 A16 S1 -2.23E-03 -1.42E-03 -1.58E-03 1.99E-03 -1.57E-03 5.89E-04 -1.03E-04 S2 1.67E-02 7.72E-03 -1.95E-02 1.86E-02 -1.03E-02 2.99E-03 -3.52E-04 S3 -1.20E-01 5.67E-02 -1.58E-02 -4.32E-03 7.03E-03 -3.69E-03 9.15E-04 S4 -1.73E-01 5.10E-02 3.32E-02 -1.27E-01 1.55E-01 -1.00E-01 2.67E-02 S5 -1.72E-01 -1.25E-01 2.28E-01 -2.68E-01 -1.55E-03 1.94E-01 -9.58E-02 S6 -7.33E-02 -3.25E-01 5.71E-01 -5.50E-01 3.28E-01 -1.16E-01 1.79E-02 S7 -5.79E-02 -2.38E-01 2.45E-01 8.42E-02 -2.58E-01 1.48E-01 -3.04E-02 S8 -9.98E-02 -7.16E-02 1.25E-01 -4.70E-02 1.29E-03 4.62E-04 3.80E-05

[0094] Table 5

[0095] The difference between the projection lenses 210, 220, and 230 in embodiments 1, 2, and 3 of the second embodiment lies in the different structural dimensions of the included lens barrel and isolator. Tables 6-1 and 6-2 provide some basic parameters of the lens barrel and isolator of the projection lenses 210, 220, and 230 of the second embodiment, such as d1s, d1m, D1m, d2s, d3s, d3m, D3m, d0s, d0m, EP01, CP1, EP12, CP2, EP23, and L, etc. The basic parameters listed in Tables 6-1 and 6-2 are based on... Figure 1 The measurements were obtained using the annotation method shown, and the units of the basic parameters listed in Tables 6-1 and 6-2 are all millimeters (mm).

[0096] Example / Parameter d1s d1m D1m d2s d3s d3m D3m d0s 2-1 3.374 3.151 4.620 2.113 2.535 2.535 5.100 4.499 2-2 2.655 2.655 4.700 2.158 2.519 2.519 5.000 4.499 2-3 3.303 3.259 4.640 2.113 2.575 2.575 3.741 4.499

[0097] Table 6-1

[0098] Example / Parameter d0m EP01 CP1 EP12 CP2 EP23 L 2-1 5.269 1.222 0.310 0.594 0.018 1.683 4.425 2-2 5.169 1.368 0.018 0.741 0.018 1.683 4.425 2-3 5.313 1.222 0.310 0.594 0.018 1.683 4.425

[0099] Table 6-2

[0100] Figure 9A The on-axis chromatic aberration curves of the projection lenses 210, 220 and 230 of the second embodiment are shown, which indicate the deflection of the focal point of light of different wavelengths after passing through the projection lenses 210, 220 and 230. Figure 9B The astigmatism curves of projection lenses 210, 220 and 230 of the second embodiment are shown, which represent the meridional image plane curvature and sagittal image plane curvature corresponding to different field of view angles. Figure 9C The distortion curves of the projection lenses 210, 220 and 230 of the second embodiment are shown, which represent the distortion magnitude values ​​corresponding to different field of view angles. Figure 9DThe magnification chromatic aberration curves of projection lenses 210, 220, and 230 of the second embodiment are shown, representing the deviations in image height on the projection surface after light passes through the lenses. According to Figures 9A to 9D It can be seen that the projection lenses 210, 220 and 230 of the second embodiment can achieve good imaging quality.

[0101] Third Implementation Method

[0102] The following is for reference Figures 10 to 13D Describes a projection lens according to a third embodiment of this application. Figure 10 A schematic diagram of the projection lens 310 according to Embodiment 1 of the third embodiment of this application is shown; Figure 11 A schematic diagram of the projection lens 320 according to Embodiment 2 of the third embodiment of this application is shown; Figure 12 A schematic diagram of the projection lens 330 according to Embodiment 3 of the third embodiment of this application is shown.

[0103] like Figures 10 to 12 As shown, projection lenses 310, 320, and 330 each include a lens barrel P0, a four-element imaging lens group housed within the lens barrel P0, and multiple isolators. The four-element imaging lens group, from the imaging side to the image source side, includes: a first lens E1, a second lens E2, a third lens E3, and a fourth lens E4. An aperture stop STO can be positioned between the imaging side and the first lens E1 as needed. The multiple isolators include: a first isolator P1, a second isolator P2, and a third isolator P3. The isolators prevent excess light from entering the next lens during the imaging process, allowing the lens to better contact the lens barrel P0 and enhancing the structural stability of the projection lens.

[0104] The first lens E1 has positive optical power, with its imaging-side surface S1 being convex and its image-source-side surface S2 being convex. The second lens E2 has negative optical power, with its imaging-side surface S3 being convex and its image-source-side surface S4 being concave. The third lens E3 has negative optical power, with its imaging-side surface S5 being convex and its image-source-side surface S6 being concave. The fourth lens E4 has negative optical power, with its imaging-side surface S7 being convex and its image-source-side surface S8 being concave. The filter has an imaging-side surface S9 (not shown) and an image-source-side surface S10 (not shown). Light from the image-source surface S11 (not shown) passes sequentially through each surface S10 to S1 and is finally projected onto a projection surface (not shown) disposed on the imaging side. When the projection lens is applied to, for example, VR or AR devices, light from the image-source surface passes sequentially through each surface S10 to S1 and can finally be projected onto the human eye for imaging.

[0105] Table 7 shows the basic parameters of the projection lens in the third embodiment, where the units for radius of curvature, thickness / distance, and focal length are all millimeters (mm).

[0106]

[0107] Table 7

[0108] In this embodiment, the total effective focal length of the projection lens is 5.85 mm, half of the maximum field of view of the projection lens is 15.72°, and the entrance pupil diameter (EPD) of the projection lens is 3.01 mm.

[0109] In the third embodiment, the imaging-side surface and the image source-side surface of any one of the first lens E1 to the fourth lens E4 are aspherical. Table 8 shows the higher-order coefficients A4, A6, A8, and A6 that can be used for each aspherical mirror S1-S8 in the third embodiment. 10 A 12 A 14 and A 16 .

[0110] Face number A4 A6 A8 A10 A12 A14 A16 S1 1.47E-03 -5.94E-03 7.38E-03 -6.52E-03 3.58E-03 -1.14E-03 1.55E-04 S2 -5.01E-02 1.11E-01 -1.07E-01 5.70E-02 -1.72E-02 2.63E-03 -1.29E-04 S3 -1.38E-01 6.94E-02 4.29E-02 -1.22E-01 9.50E-02 -3.33E-02 4.53E-03 S4 -1.25E-01 -1.83E-02 1.67E-01 -2.51E-01 1.84E-01 -6.82E-02 1.02E-02 S5 -6.87E-02 -2.09E-02 2.28E-02 -7.25E-02 8.82E-02 -5.35E-02 1.22E-02 S6 -8.34E-02 -1.31E-02 4.27E-02 -8.70E-02 5.90E-02 -1.25E-02 -1.01E-03 S7 -9.28E-02 -7.65E-03 7.63E-03 2.69E-02 -9.02E-02 7.41E-02 -1.99E-02 S8 -7.19E-02 -2.00E-02 4.72E-02 -4.83E-02 2.53E-02 -6.52E-03 6.46E-04

[0111] Table 8

[0112] The difference between the projection lenses 310, 320, and 330 in embodiments 1, 2, and 3 of the third embodiment lies in the different structural dimensions of the included lens barrel and isolator. Tables 9-1 and 9-2 provide some basic parameters of the lens barrel and isolator of the projection lenses 310, 320, and 330 of the third embodiment, such as d1s, d1m, D1m, d2s, d3s, d3m, D3m, d0s, d0m, EP01, CP1, EP12, CP2, EP23, and L, etc. The basic parameters listed in Tables 9-1 and 9-2 are based on... Figure 1 The measurements were obtained using the annotation method shown, and the units of the basic parameters listed in Tables 9-1 and 9-2 are all millimeters (mm).

[0113] Example / Parameters d1s d1m D1m d2s d3s d3m D3m d0s 3-1 2.646 2.646 4.931 3.349 2.424 2.424 5.491 4.631 3-2 2.680 2.680 4.061 3.435 2.451 2.451 5.431 4.631 3-3 2.646 2.646 4.931 3.384 2.458 2.458 3.936 4.631

[0114] Table 9-1

[0115] Example / Parameters d0m EP01 CP1 EP12 CP2 EP23 L 3-1 5.681 1.448 0.018 0.596 0.747 1.521 5.379 3-2 5.621 1.448 0.018 0.596 0.747 1.521 5.379 3-3 5.681 1.448 0.018 0.596 0.727 1.553 5.379

[0116] Table 9-2

[0117] Figure 13A The on-axis chromatic aberration curves of the projection lenses 310, 320 and 330 of the third embodiment are shown, which indicate the deflection of the focal point after light of different wavelengths passes through the projection lenses 310, 320 and 330. Figure 13B The astigmatism curves of projection lenses 310, 320, and 330 of the third embodiment are shown, which represent the meridional image plane curvature and sagittal image plane curvature corresponding to different field of view angles. Figure 13CThe distortion curves of the projection lenses 310, 320 and 330 of the third embodiment are shown, which represent the distortion magnitude values ​​corresponding to different field of view angles. Figure 13D The magnification chromatic aberration curves of projection lenses 310, 320, and 330 of the third embodiment are shown, representing the deviations in image height on the projection surface after light passes through the lens. According to Figures 13A to 13D It can be seen that the projection lenses 310, 320 and 330 of the third embodiment can achieve good imaging quality.

[0118] In summary, the conditional expressions of each embodiment in the first to third embodiments satisfy the relationships shown in Table 10.

[0119] Conditional / Example 1-1 1-2 1-3 2-1 2-2 2-3 3-1 3-2 3-3 |(R4-R5) / EP23| 26.18 27.30 27.03 15.62 15.62 15.62 10.09 10.09 9.88 R6 / d3s+R7 / d3m 2.72 2.81 2.72 3.86 3.89 3.80 5.15 5.09 5.08 EPD / (d0m-d0s) 4.78 4.78 4.78 3.91 4.49 3.70 2.86 3.04 2.86 (d2s-d1s) / (N2-N1) -6.45 -6.68 -2.93 -7.69 -3.03 -7.25 4.29 4.60 4.50 (f1+f2+f3) / EP23 -5.00 -5.22 -5.16 -4.57 -4.57 -4.57 -11.09 -11.09 -10.86 CP1 / T12+CP2 / T23 6.33 6.73 0.37 7.31 0.43 7.31 1.03 1.03 1.02 |f / (D3m-D1m)| 11.15 8.81 19.33 11.46 18.33 6.12 10.45 4.27 5.88 L / f 0.76 0.76 0.76 0.80 0.80 0.80 0.92 0.92 0.92 (R1-R2) / (EP01×N1) 15.88 14.20 15.88 10.84 9.69 10.84 43.78 43.78 43.78 (d0s×CT1) / EP01 4.01 3.58 4.01 4.40 3.94 4.40 3.11 3.11 3.11 (R5+R7) / d3s -14.78 -15.25 -14.76 -6.96 -7.01 -6.85 10.99 10.86 10.84 |f3| / EP23+f2 / EP12 -15.25 -11.10 -10.74 -9.34 -7.02 -9.34 -18.96 -18.96 -19.05 (d1s×R2) / (d1m×R3) -15.49 -15.36 -14.29 -10.25 -9.57 -9.70 -38.84 -38.84 -38.84

[0120] Table 10

[0121] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A projection lens, characterized in that, include: A four-element imaging lens group includes a first lens, a second lens, a third lens, and a fourth lens arranged sequentially along the optical axis from the imaging side to the image source side; The first lens has positive optical power, and its imaging side surface is convex, as is its image source side surface. The second lens has negative optical power, and its imaging side surface is convex while its image source side surface is concave. The third lens has negative optical power and its image source side surface is concave. The fourth lens has positive or negative optical power, and its imaging side surface is convex. The projection lens has four lenses with optical power. A plurality of isolating members, including a first isolating member, a second isolating member, and a third isolating member, wherein the first isolating member is disposed on and in contact with the image source side surface of the first lens, the second isolating member is disposed on and in contact with the image source side surface of the second lens, and the third isolating member is disposed on and in contact with the image source side surface of the third lens; and The lens barrel, in which the four-element imaging lens group and the plurality of spacers are placed, contains the lens barrel. Wherein, the radius of curvature R4 of the image source side surface of the second lens, the radius of curvature R5 of the imaging side surface of the third lens, and the spacing EP23 of the second and third isolators along the optical axis satisfy: 9.88≤|(R4-R5) / EP23|≤27.30, and The radius of curvature R6 of the image source side surface of the third lens, the radius of curvature R7 of the imaging side surface of the fourth lens, the inner diameter d3s of the imaging side surface of the third isolator, and the inner diameter d3m of the image source side surface of the third isolator satisfy: 2.72≤R6 / d3s+R7 / d3m≤5.

15. The inner diameter d1s of the imaging side surface of the first isolator, the inner diameter d1m of the image source side surface of the first isolator, the radius of curvature R2 of the image source side surface of the first lens, and the radius of curvature R3 of the imaging side surface of the second lens satisfy: -38.84≤(d1s×R2) / (d1m×R3)≤-9.

57.

2. The projection lens according to claim 1, characterized in that, The entrance pupil diameter EPD of the projection lens, the inner diameter d0s of the imaging side surface of the lens barrel, and the inner diameter d0m of the image source side surface of the lens barrel satisfy the following condition: 2.86≤EPD / (d0m-d0s)≤4.

78.

3. The projection lens according to claim 1, characterized in that, The first lens is a glass lens, and the refractive index of the first lens is less than 1.

53.

4. The projection lens according to claim 3, characterized in that, The inner diameter d1s of the imaging side surface of the first isolator, the inner diameter d2s of the imaging side surface of the second isolator, the refractive index N1 of the first lens and the refractive index N2 of the second lens satisfy: -7.69mm≤(d2s-d1s) / (N2-N1)≤4.60mm.

5. The projection lens according to claim 1, characterized in that, The effective focal length f1 of the first lens, the effective focal length f2 of the second lens, the effective focal length f3 of the third lens, and the spacing EP23 of the second and third isolators along the optical axis satisfy: -11.09≤(f1+f2+f3) / EP23≤-4.

57.

6. The projection lens according to claim 1, characterized in that, The maximum thickness CP1 of the first isolator, the air gap T12 between the first lens and the second lens on the optical axis, the maximum thickness CP2 of the second isolator, and the air gap T23 between the second lens and the third lens on the optical axis satisfy: 0.37≤CP1 / T12+CP2 / T23≤7.

31.

7. The projection lens according to claim 1, characterized in that, The total effective focal length f of the projection lens, the outer diameter D1m of the image source side surface of the first isolation member, and the outer diameter D3m of the image source side surface of the third isolation member satisfy: 4.27≤|f / (D3m-D1m)|≤19.

33.

8. The projection lens according to claim 1, characterized in that, The length L of the lens barrel in the direction of the optical axis and the total effective focal length f of the projection lens satisfy the following condition: 0.76≤L / f≤0.

92.

9. The projection lens according to claim 1, characterized in that, The radius of curvature R1 of the imaging side surface of the first lens, the radius of curvature R2 of the image source side surface of the first lens, the distance EP01 between the imaging side surface of the lens barrel and the first isolator along the optical axis and the refractive index N1 of the first lens satisfy: 9.69≤(R1-R2) / (EP01×N1)≤43.

78.

10. The projection lens according to claim 1, characterized in that, The inner diameter d0s of the imaging side surface of the lens barrel, the distance EP01 between the imaging side surface of the lens barrel and the first isolator along the optical axis, and the center thickness CT1 of the first lens on the optical axis satisfy the following: 3.11mm≤(d0s×CT1) / EP01≤4.40mm.

11. The projection lens according to claim 1, characterized in that, The radius of curvature R5 of the imaging side surface of the third lens, the radius of curvature R7 of the imaging side surface of the fourth lens, and the inner diameter d3s of the imaging side surface of the third isolator satisfy: -15.25≤(R5+R7) / d3s≤10.

99.

12. The projection lens according to claim 1, characterized in that, The effective focal length f2 of the second lens, the effective focal length f3 of the third lens, the distance EP12 between the first and second isolators along the optical axis, and the distance EP23 between the second and third isolators along the optical axis satisfy: -19.05≤|f3| / EP23+f2 / EP12≤-7.02.

Images