Projection lenses and projection equipment

Abstract

The present application discloses a projection lens and a projection device, belonging to the field of projection technology. The projection lens includes a refractive lens group and a reflective lens group; the refractive lens group includes a first lens group, a second lens group, and a third lens group arranged in sequence along the light-emitting direction, the first lens group, the second lens group, and the third lens group satisfying 2<|F2 / F1|<12, 0.5<|F3 / F1|<5, and 1<|F4 / F1|<10, and the first lens group includes nine lenses arranged along the light-emitting direction. The present application provides a structure of a projection lens, wherein the focal lengths of the three lens groups in the refractive lens group satisfy corresponding proportional relationships, so that the lens can achieve higher imaging requirements with a smaller size. This solves the problem of difficulty in reducing the volume of the projection lens in the related art, and achieves the effect of reducing the volume of the projection lens.

Description

Technical Field

[0001] The present application relates to the field of projection technology, and in particular to a projection lens and a projection device. Background Art

[0002] With the advancement of science and technology, and the application of home projection equipment, such as laser ultra-short-throw projectors, users can present large-scale, high-definition images with a wide color gamut and brightness even when placed against a wall. This high-quality image is not only due to the use of laser as a light source, but also due to the high-resolution ultra-short-throw lens, which is also a key component of laser projection equipment. The higher the resolution of the projection lens, the better the user's viewing experience.

[0003] During lens design, multiple requirements must be considered. For example, projection lenses must be designed in conjunction with the lighting system. Lighting systems are categorized as either telecentric or non-telecentric, so projection lenses are designed to be telecentric or non-telecentric, respectively, and their beam reception and confinement capabilities differ.

[0004] Furthermore, the improvement in the resolution of projection lenses generally leads to an increase in the number of lenses used, making the design of the lens surface more difficult.

[0005] To achieve high resolution and a short focal length, projection lenses typically require a complex lens assembly. This results in a more complex overall structure, hindering lens size reduction. The projection lens accounts for over one-third of the optical engine of a projection device, making it difficult to reduce the overall size of the laser projection device, resulting in a bulky and heavy device. Summary of the Invention

[0006] The present application provides a projection lens and a projection device. The technical solution is as follows:

[0007] According to a first aspect of the present application, a projection lens is provided, comprising a refractive lens group and a reflective lens group arranged along a light emitting direction of a light valve;

[0008] The refractive lens group includes a first lens group, a second lens group, and a third lens group sequentially arranged along the light emitting direction, wherein the first lens group, the second lens group, and the third lens group satisfy 2<|F2 / F1|<12, 0.5<|F3 / F1|<5, and 1<|F4 / F1|<10, F1 is the equivalent focal length of the projection lens, F2 is the equivalent focal length of the first lens group, F3 is the equivalent focal length of the second lens group, and F4 is the equivalent focal length of the third lens group;

[0009] The first lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a ninth lens arranged along the light emitting direction, the third lens, the fourth lens, and the fifth lens constitute a triplet lens, the seventh lens and the eighth lens constitute a doublet lens, the second lens is an aspherical lens, and the other lenses in the first lens group except the second lens are spherical lenses.

[0010] Optionally, the refracting mirror group and the reflecting mirror group satisfy 1.07<L1 / L2<1.47, 0.05<B / (L1+L2)<0.25, L1 is the length of the refracting mirror group, L2 is the distance between the refracting mirror group and the reflecting mirror group, and B is the distance between the refracting mirror group and the light valve.

[0011] Optionally, the projection lens further includes an aperture stop, and the aperture stop is located between the fifth lens and the sixth lens of the first lens group.

[0012] Optionally, the optical powers of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens and the ninth lens are positive, positive, positive, negative, positive, positive, positive, negative, positive, in sequence.

[0013] Optionally, the second lens group includes a tenth lens, an eleventh lens, and a twelfth lens, and the optical power of the tenth lens, the eleventh lens, and the twelfth lens are positive, positive, and negative respectively;

[0014] Wherein, the lenses in the second lens group are all spherical lenses.

[0015] Optionally, the refraction mirror group and the reflection mirror group also meet the 0.25

[0016] The reflector group includes a curved reflector, and the curved reflector satisfies 32 mm ≤ (|R|*IC) / 17.65 ≤ 47 mm, -5 ≤ C ≤ 0, where R is the central curvature radius of the curved reflector, IC is the image circle size of the projection lens, and C is the conic coefficient of the curved reflector.

[0017] Optionally, the third lens group includes a thirteenth lens, the thirteenth lens has a negative optical power and is an aspherical lens.

[0018] Optionally, the second lens group includes a tenth lens, the third lens group includes an eleventh lens, a twelfth lens and a thirteenth lens arranged along the light emitting direction, the tenth lens, the eleventh lens and the twelfth lens are all spherical lenses, and the thirteenth lens is an aspherical lens.​

[0019] Optionally, the optical focal length of the second lens group is positive, the optical focal lengths of the eleventh lens, the twelfth lens, and the thirteenth lens are positive, negative, and negative, respectively, and the optical focal lengths of the refractive lens group and the reflective lens group are both positive.

[0020] According to another aspect of the present application, a projection device is provided, comprising a light valve, a galvanometer, and any one of the projection lenses described above, wherein the galvanometer is located between the light valve and the projection lens.

[0021] The beneficial effects of the technical solutions provided in the embodiments of the present application include at least:

[0022] A projection lens structure is provided, comprising a refractive lens group and a reflective lens group. The focal lengths of the three lens groups in the refractive lens group are proportional to each other. The first lens group includes one aspherical lens and eight spherical lenses. This allows the lens to achieve high imaging requirements with a relatively small size. Compared with refractive lens groups composed of multiple lenses in related art, the lens size can be smaller. This solves the problem in related art that the refractive lens group has a large number of lenses, making it difficult to reduce the lens volume. A smaller projection lens is provided, and a projection device using the projection lens can also be simplified in structure, facilitating compactness. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0024] Figure 1 1 is a schematic diagram of a projection imaging process of a projection lens provided in an embodiment of the present application;

[0025] Figure 2 1 is a schematic structural diagram of a projection lens provided in an embodiment of the present application;

[0026] Figure 3 is a schematic structural diagram of another projection lens provided in an embodiment of the present application;

[0027] Figure 4 This is a schematic structural diagram of an optical engine provided by an embodiment of the present application;

[0028] Figure 5 is a structural diagram of another optical engine provided in an embodiment of the present application;

[0029] Figure 6is a structural diagram of another optical engine provided in an embodiment of the present application;

[0030] Figure 7 It is a structural schematic diagram of a projection device provided in an embodiment of the present application.

[0031] The above drawings illustrate specific embodiments of the present application, which will be described in more detail below. These drawings and the textual description are not intended to limit the scope of the present application in any way, but rather to illustrate the concepts of the present application to those skilled in the art by reference to specific embodiments. DETAILED DESCRIPTION

[0032] In order to make the objectives, technical solutions and advantages of this application clearer, the implementation methods of this application will be further described in detail below with reference to the accompanying drawings.

[0033] Figure 1 1 is a schematic diagram of a projection imaging process of a projection lens provided in an embodiment of the present application. The implementation environment may include a projection screen 10 and a projection lens 20.

[0034] The projection lens 20 can project an image beam onto the projection screen 10, and the image beam can form an image on the screen 10. The current development trend is to reduce the projection ratio of the projection lens 20 (the projection ratio is the ratio of the projection distance s to the diagonal length h of the screen, and the projection distance s is the lateral distance between the projection lens 20 and the projection screen 10). The smaller the projection ratio, the closer the laser projection device can be set to the wall (the plane where the projection screen is located), without having to reserve a sufficient distance to form an image like a telephoto lens. The projection lens 20 can project a larger screen within a very short projection distance, and the projection device host and screen are also more likely to be an integrated device. The above-mentioned projection lens with a smaller projection ratio can be called a short-focus or ultra-short-focus projection lens.

[0035] However, projection lenses with relatively small throw sizes can exhibit various aberrations, such as distortion, astigmatism, field curvature, and coma. To overcome these aberrations, conventional projection lenses employ a large number of lenses (typically over 16, but around 20) and a wide variety of different types. These lenses also employ numerous doublets and triplets, as well as numerous aspherical lenses. This results in a complex system structure, making it difficult to reduce system length, limiting manufacturability, and making costs difficult to control.

[0036] The embodiments of the present application provide a projection lens and a projection device, which can solve the problems existing in the above-mentioned related technologies.

[0037] Figure 22 is a schematic structural diagram of a projection lens provided by an embodiment of the present application. The projection lens 20 may include a refractive lens group 21 and a reflective lens group 22 arranged along the light emitting direction f of the light valve.

[0038] The refractive lens group includes a first lens group 211, a second lens group 212 and a third lens group 213 arranged in sequence along the light output direction. The first lens group 211, the second lens group 212 and the third lens group 213 satisfy 2<|F2 / F1|<12, 20<|F3 / F1|<35 and 10<|F4 / F1|<25.

[0039] Wherein, F1 is the equivalent focal length of the projection lens 20 , F2 is the equivalent focal length of the first lens group 211 , F3 is the equivalent focal length of the second lens group 212 , F4 is the equivalent focal length of the third lens group 213 , and F5 is the equivalent focal length of the reflector group 22 .

[0040] The first lens group 211 includes a first lens j1, a second lens j2, a third lens j3, a fourth lens j4, a fifth lens j5, a sixth lens j6, a seventh lens j7, an eighth lens j8, and a ninth lens j9, arranged along the light-emitting direction f. The third lens j3, the fourth lens j4, and the fifth lens j5 form a triplet lens h1, and the seventh lens j7 and the eighth lens j8 form a doublet lens h2. The triplet lens h1, formed by the third lens j3, the fourth lens j4, and the fifth lens j5, can be used to correct spherical aberration, coma, and astigmatism of the projection lens. The doublet lens h2, formed by the seventh lens j7 and the eighth lens j8, can also be used to correct spherical aberration, coma, and astigmatism of the projection lens.

[0041] The second lens j2 is an aspheric lens (for example, a rotationally symmetric aspheric lens), and all other lenses in the first lens group, except the second lens j2, are spherical lenses. That is, the first lens j1, the third lens j3, the fourth lens j4, the fifth lens j5, the sixth lens j6, the seventh lens j7, the eighth lens j8, and the ninth lens j9 are all spherical lenses. The second lens j2 can correct coma and spherical aberration of the system.

[0042] Optionally, the refracting mirror group 21 and the reflecting mirror 22 satisfy 1.05<L1 / L2<1.5, 0.05<B / (L1+L2)<0.25, L1 is the length of the refracting mirror group, L2 is the distance between the refracting mirror group 21 and the reflecting mirror group, and B is the distance between the refracting mirror group and the light valve.

[0043] Optionally, the refraction mirror group 21 and the reflection mirror group 22 also meet the 0.25

[0044] ​The reflector assembly 22 includes a curved reflector that satisfies the following conditions: 32 mm ≤ (|R|*IC) / 17.65 ≤ 47 mm, -5 ≤ C ≤ 0, where R is the central radius of curvature of the curved reflector, IC is the image circle of the projection lens 20 (the image circle is also called the image circle, which is the range of maximum image clarity of the lens on the light valve plane, or the range of the effective image circle of the focal plane formed by connecting the perpendicular lines through the optical axis of the projection lens), and C is the conic coefficient of the curved reflector. The equivalent focal length of the reflector assembly is related to the central radius of curvature and the conic coefficient of the curved reflector. When the size of the light valve changes, the central radius of curvature increases or decreases proportionally, and the conic coefficient does not change. It should be noted that the light valve 31 may not be included in the projection lens provided in the embodiments of this application.

[0045] In the embodiment of the present application, the distance between the refractive mirror assembly and the light valve may be referred to as a back working distance, which may be relatively short, for example, 20.8 mm.

[0046] In summary, the projection lens provided in the embodiment of the present application includes a refractive lens group and a reflective lens group. The focal lengths of the three lens groups in the refractive lens group satisfy corresponding proportional relationships. The first lens group includes an aspherical lens and eight spherical lenses, thereby enabling the lens to achieve higher imaging requirements with a smaller size. Compared with the refractive lens group composed of more lenses in the related art, the size of the lens can be smaller. This solves the problem in the related art that the refractive lens group has a large number of lenses and is difficult to reduce the lens volume. A smaller projection lens is provided, and the structure of the projection device using the above-mentioned projection lens can also be simplified accordingly, which facilitates volume compression. The embodiment of the present application provides a new projection lens solution.

[0047] Figure 3 This is a schematic diagram of the structure of another projection lens provided in an embodiment of the present application. Figure 2 The projection lens shown has been modified with some adjustments.

[0048] In the projection lens, the optical axes of the first lens group 211 , the second lens group 212 and the third lens group 213 may be collinear.

[0049] Optionally, the projection lens 21 further includes an aperture diaphragm 23, which is located between the fifth lens j5 and the sixth lens j6 of the first lens group 211. The aperture diaphragm 23 can control aberration correction and the diameter of the entrance pupil.

[0050] The optical power of lenses in an optical system directly affects astigmatism, field curvature, distortion, axial chromatic aberration, and transverse chromatic aberration. Therefore, different combinations of positive and negative optical powers also play a role in aberration correction. In an exemplary embodiment, the first lens group 211 includes a first lens j1, a second lens j2, a third lens j3, a fourth lens j4, a fifth lens j5, a sixth lens j6, a seventh lens j7, an eighth lens j8, and a ninth lens j9, arranged along the light output direction f. The optical powers are positive, positive, positive, negative, positive, positive, positive, positive, negative, and positive, respectively.

[0051] Optionally, the second lens group 212 includes a tenth lens j10, an eleventh lens j11 and a twelfth lens j12, and the optical power of the tenth lens j10, the eleventh lens j11 and the twelfth lens j12 is positive, positive and negative respectively.

[0052] The lenses in the second lens group 212 are all spherical lenses.

[0053] Optionally, the third lens group 213 includes a thirteenth lens j13, which has a negative optical power and is an aspheric lens (for example, a rotationally symmetric aspheric lens). As an aspheric lens, the thirteenth lens t13 can correct the astigmatism, field curvature, and distortion of the system.

[0054] The thirteenth lens t13 is made of 330R material (an optical material) and can be manufactured by molding.

[0055] Optionally, the curved reflector included in the reflector group 22 is an aspheric concave reflector, which is used to reflect the output light of the projection lens onto the screen for imaging. The aspheric concave reflector can be an axisymmetric aspheric concave reflector.

[0056] In this embodiment, the effective focal length (EFL) of the projection lens is 1.85 mm, the resolution is 93 lp / mm, the projected image area is 25-40 inches, and the throw ratio is 0.3.

[0057] The projection lens provided in the embodiment of the present application has a relatively small number of lenses, less than 14, and also has a relatively small number of aspherical lenses, which greatly reduces the complexity and size of the projection lens. In addition, the aspherical lenses are made of 330R plastic material, which is low-cost and easy to process (manufactured by molding). Therefore, the projection lens has been greatly improved in terms of size, complexity, cost, and processing.

[0058] In the embodiment of the present application, the second lens group is a movable lens group, that is, the second lens group can be moved along the optical axis to perform operations such as focusing or adjusting the focal length. In addition, the first lens group, the third lens group, and the reflector lens group are also fine-tunable lens groups to cooperate with the second lens group for adjustment.

[0059] The projection lens provided in the embodiment of the present application can be an ultra-short-throw projection lens. The total length of the projection lens can be 156.35 mm, the maximum semi-aperture diameter of the aspheric reflector can be 38 mm, and the overall volume is relatively small.

[0060] In summary, the projection lens provided in the embodiments of the present application achieves high imaging requirements with a relatively small size by ensuring that the refractive lens group and the reflective lens group meet corresponding distance parameter ranges and that the focal lengths of the three lens groups in the refractive lens group meet corresponding proportional relationships. Compared to refractive lens groups composed of multiple lenses in the related art, the lens size can be smaller. This solves the problem in the related art that the refractive lens group has a large number of lenses, making it difficult to reduce the lens volume. A smaller projection lens is provided, and the structure of the projection device using this projection lens can also be simplified, facilitating compactness.

[0061] Figure 4 The optical engine 50 includes a light valve 51 and a polarization beam splitter prism 52, a galvanometer 53 and a light valve 51 arranged in sequence along the light output direction f of the light valve 51. Figure 3 The projection lens shown.

[0062] Optionally, the light valve 51 can be a 0.33-inch Liquid Crystal on Silicon (LCOS) light valve. LCOS is a very small matrix liquid crystal display component based on a reflective mode. This matrix is manufactured on a silicon chip using complementary metal oxide semiconductor (CMOS) technology. LCOS uses a reflective projection method, and its light utilization efficiency can reach over 40%. Its biggest advantage is that it can be produced using the widely used and low-cost CMOS manufacturing technology without the need for additional investment. It can also gradually improve its resolution as the semiconductor process becomes increasingly miniaturized. The 0.33-inch LCOS light valve can provide a 720p image.

[0063] The polarization beam splitter prism 52 is located between the light valve 51 and the galvanometer 53 and is used to separate the illumination beam and the imaging beam. The polarization beam splitter prism 52 can be a total internal reflection (TIR) prism or a reverse total internal reflection (RTIR) prism.

[0064] Optionally, the galvanometer 53 is located between the polarization beam splitter prism 52 and the projection lens 20 and is used to shift the image beam by vibrating, thereby improving the resolution of the image projected onto the screen.

[0065] The vibration of the galvanometer mirror makes the image beams corresponding to the two adjacent frames of projection images passing through the vibrating lens not completely overlap, and the image beams corresponding to the two adjacent frames of projection images are sequentially projected to the refractive mirror group. The projected image is the image presented on the projection screen after the image beams pass through the projection lens.

[0066] Exemplarily, the galvanometer includes flat glass and a driving component. The flat glass can vibrate under the drive of the driving component. The vibration of the flat glass makes the image light beams corresponding to two adjacent frames of projection images passing through the flat glass not completely overlap, so that the image light beams directed to the same pixel increase, thereby improving the resolution of the imaging. Moreover, due to the vibration of the flat glass, the image light beams corresponding to two adjacent frames of projection images are slightly staggered, thereby making the transition between pixels smoother, thereby increasing the details of the picture, visually improving the clarity of the picture, and thus improving the imaging quality. By utilizing the effect of persistence of vision of the human eye, for the user, the resolution of the picture he watches is improved, with the effect of "doubling" the resolution.

[0067] When the flat glass vibrates frequently between two positions, two sub-pictures are displayed in a staggered and superimposed manner. When the flat glass vibrates frequently between four positions, four sub-pictures are displayed in a staggered and superimposed manner, so as to achieve a double or quadruple increase in visual resolution.

[0068] For example, when the incident light beam on the galvanometer is parallel (i.e., each ray in the beam has the same angle of incidence), after the optical lens in the galvanometer swings from one position to another, the displacement distance of each pixel in the projected image corresponding to the image beam is equal, so that the offset between each field of view in the projection lens and the projection screen is consistent, thus ensuring high-resolution display of the visual image. The field of view offset refers to the actual displacement distance of the field of view.

[0069] In related technologies, a 0.33-inch light valve can provide a 720p image. Current projection devices mostly have a 720p display resolution and often use light-emitting diodes (LEDs) as light sources to achieve compactness. However, due to the performance limitations of LEDs, achieving high brightness is difficult. Consequently, micro-projectors that combine high resolution and brightness with compactness are rare on the market. Lenses, a core technology in projection display, are challenging to design and manufacture. Striking a balance between cost and miniaturization while maintaining image quality is a major challenge in lens design.

[0070] In an embodiment of the present application, a light valve based on 0.33-inch silicon-based liquid crystal is provided, which is combined with an ultra-short-focus projection lens and a galvanometer 53 to project an image with a resolution of 1080p on a screen. In addition, the number of lenses in the projection lens is relatively small, less than 14, and the number of aspherical lenses is also relatively small, which greatly reduces the complexity and volume of the projection lens. In addition, the aspherical lenses are made of 330R plastic material, which is low-cost and easy to process (manufactured by molding), so the projection lens has been greatly improved in terms of volume, complexity, cost and processing. In addition, the projection lens can be used with a laser light source, which can greatly improve the brightness of the image.

[0071] In the projection imaging system of this embodiment, the offset of the pixel surface of the light valve 51 relative to the optical axis satisfies the relationship: 147% <offset<155%。

[0072] In the projection imaging system of this embodiment, the linear relationship between the straight-line distance between the reflector group and the screen and the length of the projected image (ie, the projection ratio) satisfies the following: projection distance / screen length ≤ 3.

[0073] The projection lens provided in the present application can be a secondary imaging architecture, in which the pixel surface of the light valve is the object surface. After the light beam emitted from the light valve passes through the refractive mirror group, the first imaging is performed between the reflective mirror group and the refractive mirror group (the light beam forms a convergence point once, which is a primary imaging). After the first imaging is reflected by the reflective mirror group, a secondary distortion-free image is formed on the screen. After the secondary imaging is performed, a large-size projection image is displayed on the projection screen.

[0074] The optical engine provided in the embodiment of the present application projects an image on a screen with a size of 28 inches (619x348mm). 2 ), the maximum TV distortion is -1.4707%.

[0075] Figure 5Schematic diagram of another optical engine provided by an embodiment of the present application. The optical engine 50 includes a light source device 54, a light valve 51, a polarization beam splitter prism 52, a galvanometer 53 and Figure 3 The polarization beam splitter prism 52 can be a total internal reflection prism.

[0076] The light source device 54 may include various components such as a laser light source 541 , a light adjustment component 542 , and a light uniforming component 543 .

[0077] The laser light source 541 is used to provide laser light, and the light adjustment component 542 is used to adjust the laser light provided by the laser light source 541 into primary color light and output it. For example, if the laser light source 541 provides blue laser light, the light adjustment component 542 can adjust the blue laser light into blue laser light, red laser light, and green laser light.

[0078] Optionally, the light homogenizing device 543 includes a light pipe, which is a tubular device made of four flat reflective sheets, that is, a hollow light pipe. The light is reflected multiple times inside the light pipe to achieve a light homogenizing effect. The light pipe can also be a solid light pipe. The light inlet and light outlet of the light pipe are rectangles with the same shape and area. The laser beam enters from the light inlet of the light pipe and then shoots toward the light valve assembly from the light outlet of the light pipe. The beam is homogenized and the light spot is optimized in the process of passing through the light pipe.

[0079] In addition, the light homogenizer 543 may also include a fly-eye lens. A fly-eye lens is typically formed by combining a series of small lenses. Two fly-eye lens arrays are arranged in parallel to split the input laser beam spot. The split spots are then accumulated through a subsequent focusing lens, thereby achieving beam homogenization and spot optimization. In a lighting device, the light homogenizer 543 can be selected from at least one of a light pipe and a fly-eye lens, which is not limited in this embodiment of the present application.

[0080] Figure 6 Schematic diagram of another optical engine provided by an embodiment of the present application. The optical engine 50 includes a light source device 54, a light valve 51, a polarization beam splitter prism 52, a galvanometer 53 and Figure 3 The polarization beam splitter prism 52 can be a reverse total internal reflection prism.

[0081] The light source device 54 may include various components such as a laser light source 541 , a light adjustment component 542 , and a light uniforming component 543 .

[0082] The laser light source 541 is used to provide laser light, and the light adjustment component 542 is used to adjust the laser light provided by the laser light source 541 into primary color light and output it. For example, if the laser light source 541 provides blue laser light, the light adjustment component 542 can adjust the blue laser light into blue laser light, red laser light, and green laser light.

[0083] Optionally, the light homogenizing device 542 includes a light pipe, which is a tubular device made of four flat reflective sheets, that is, a hollow light pipe. The light is reflected multiple times inside the light pipe to achieve a light homogenizing effect. The light pipe can also be a solid light pipe. The light inlet and light outlet of the light pipe are rectangles with the same shape and area. The laser beam enters from the light inlet of the light pipe and then shoots toward the light valve assembly from the light outlet of the light pipe. The beam is homogenized and the light spot is optimized in the process of passing through the light pipe.

[0084] In addition, the light homogenizer 542 may also include a fly-eye lens. A fly-eye lens is typically formed by combining a series of small lenses. Two rows of fly-eye lens arrays are arranged in parallel to split the input laser beam spot. The split spots are then accumulated through a subsequent focusing lens, thereby achieving beam homogenization and spot optimization. In a lighting device, the light homogenizer 542 can be selected from at least one of a light pipe and a fly-eye lens, which is not limited in this embodiment of the present application.

[0085] like Figure 7 As shown, the embodiment of the present application also provides a projection device, including a screen 60 and Figure 4 The optical engine shown, Figure 5 The optical engine shown or Figure 6 The optical engine 50 may include the above Figure 3 A lens 20 is provided in the illustrated embodiment.

[0086] When the laser projection device is in operation, the light beam emitted by the light source device 54 is directed toward the light valve 51. The outgoing light beam of the light valve 51 is directed toward the polarization beam splitter prism 52, and then toward the galvanometer 53 via the polarization beam splitter prism 52. The galvanometer 53 guides the light beam toward the lens 20, and after the lens 20 adjusts the light beam, it is directed toward the screen 60, forming an image on the screen 60.

[0087] The projection device provided in the above-mentioned embodiment utilizes a telecentric system, with a light valve projecting a parallel light beam into the projection lens. The light valve and projection lens are further provided with a total reflection prism, or a vibrating lens. Thus, while retaining sufficient back-focus distance, the projection lens can optimize the number of lenses through the rational combination of lens groups. The first lens group includes a combination of an aspheric lens, a triplet, and a doublet, supplemented by a smaller number of spherical lenses, to correct primary aberrations, reduce the imaging burden on the rear-end lens, and facilitate simplification of the rear-end lens system. Furthermore, the aperture is positioned between the two cemented lens groups in the first lens group, which effectively controls the system aperture and facilitates aberration correction.

[0088] Also, in the above-mentioned multiple examples, by setting the second lens group as a movable group and assisting with the fine adjustment of the distances among the first lens group, the reflector, and the third lens group, the adjustment mechanism is relatively simple, and the adjustment of the projection size under the requirements of ultra-short focal length and high-definition projection can be achieved, meeting a wider range of projection requirements.

[0089] In an implementation manner of the embodiment of the present application, the projection lens parameters meet the following conditions: effective focal length (EFL) = 1.85 mm, the offset of the image plane relative to the optical axis is 135% < offset < 155%, the resolution is 93 lp / mm, the projected picture is 25 - 40 inches, and the projection ratio is 0.3.

[0090] Based on a 28-inch picture, when focusing on a smaller-sized picture (that is, adjusting the picture size to be smaller than 28 inches), the three lenses of the second lens group move simultaneously in the opposite direction of ray tracing, with the same amount of movement; when focusing on a larger-sized picture (that is, adjusting the picture size to be larger than 28 inches), the three lenses of the second lens group move simultaneously in the direction of ray tracing, with the same amount of movement.

[0091] In the present application, terms such as "first", "second", "third", "fourth"... "thirteenth" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. The term "multiple" means two or more, unless otherwise clearly defined. [[ID=eleven]]

[0092] The above are only optional embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A projection lens, characterized in that: The projection lens comprises a refraction mirror group and a reflection mirror group arranged along the light output direction of the light valve; The refractive lens group consists of a first lens group, a second lens group, and a third lens group arranged in sequence along the light output direction, wherein the first lens group, the second lens group, and the third lens group satisfy 2<|F2 / F1|<12, 0.5<|F3 / F1|<5, and 1<|F4 / F1|<10, F1 is the equivalent focal length of the projection lens, F2 is the equivalent focal length of the first lens group, F3 is the equivalent focal length of the second lens group, and F4 is the equivalent focal length of the third lens group; The first lens group consists of a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a ninth lens arranged along the light emitting direction, the third lens, the fourth lens, and the fifth lens forming a triplet, the seventh lens and the eighth lens forming a doublet, the second lens being an aspherical lens, and the other lenses in the first lens group except the second lens being spherical lenses; The second lens group consists of a tenth lens, an eleventh lens and a twelfth lens, the lenses in the second lens group are all spherical lenses, and the second lens group is a movable lens group; The third lens group consists of a thirteenth lens, and the thirteenth lens is an aspherical lens; The optical powers of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens and the ninth lens are positive, positive, positive, negative, positive, positive, positive, negative and positive, respectively; the optical powers of the tenth lens, the eleventh lens and the twelfth lens are positive, positive and negative, respectively; and the optical power of the thirteenth lens is negative.

2. The projection lens according to claim 1, wherein: The refracting mirror group and the reflecting mirror group satisfy 1.07<L1 / L2<1.47, 0.05<B / (L1+L2)<0.25, where L1 is the length of the refracting mirror group, L2 is the distance between the refracting mirror group and the reflecting mirror group, and B is the distance between the refracting mirror group and the light valve.

3. The projection lens according to claim 2, wherein: The projection lens further includes an aperture stop, and the aperture stop is located between the fifth lens and the sixth lens of the first lens group.

4. The projection lens according to claim 1, wherein: The refracting mirror group and the reflecting mirror group also satisfy 0.25, the reflecting mirror group includes a curved reflecting mirror, and the curved reflecting mirror satisfies 32 mm ≤ (|R|*IC) / 17.65 ≤ 47 mm, -5 ≤ C ≤ 0, where R is the central curvature radius of the curved reflecting mirror, IC is the image circle size of the projection lens, and C is the conic coefficient of the curved reflecting mirror. The device comprises a light valve, a galvanometer, and the projection lens according to any one of claims 1 to 4, wherein the galvanometer is located between the light valve and the projection lens.

5. A projection device, characterized in that: ​

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