Projection lens and projection device

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 arranged along the light-emitting direction of the light valve; 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, and the first lens group, the second lens group, and the third lens group satisfy 2 < |F2 / F1| < 12 and 2 < |F3 / F1| < 15. The first lens group includes eight spherical lenses arranged along the light-emitting direction, including two doublet lenses composed of four transparent lenses. The present application provides a structure of a projection lens, and enables the focal lengths of the three lens groups in the refractive lens group to satisfy the corresponding proportional size relationship, so that the projection lens can achieve higher imaging requirements with a smaller size. It solves the problem that it is difficult to reduce the volume of the lens in the related art, and provides a projection lens with a smaller volume.

Description

Technical Field

[0001] This application relates to the field of projection technology, and particularly to a projection lens and a projection device. Background Art

[0002] With the improvement of science and technology, with the application of home projection devices, such as laser ultra-short throw projection devices, it is possible to present large-sized, high-definition, high-color gamut range and brightness images for users in a wall-mounted state. Among them, presenting the above high-quality images is not only because lasers are used as light sources, but also because ultra-short throw lenses with high resolution capabilities are an important part of laser projection devices. The higher the resolution ability of the projection lens, the higher the user's viewing experience.

[0003] In the process of lens design, it is necessary to take into account various requirements. For example, the projection lens needs to be designed in cooperation with the illumination system. The illumination system is divided into a telecentric illumination system and a non-telecentric illumination system, and the projection lens is correspondingly designed into a telecentric projection lens and a non-telecentric projection lens, and there are also differences in the beam reception and constraint capabilities.

[0004] In addition, usually, the improvement of the resolution ability of the projection lens increases the number of lenses used, and the design difficulty of the lens surface shape is relatively large.

[0005] That is, in order to achieve a higher resolution and a shorter focal length, the combination of lenses in the projection lens is usually relatively complex. As a result, the overall structure of the projection lens is relatively complex, which is not conducive to reducing the volume of the lens. The volume of the projection lens accounts for more than one-third of the optical engine of the projection device, which also makes it difficult to reduce the volume of the entire laser projection device, making the device appear bulky. Summary of the Invention

[0006] Embodiments of this application provide a projection lens and a projection device. The technical solutions are as follows:

[0007] According to one aspect of this application, a projection lens is provided. The projection lens includes a refractive lens group and a reflective lens group arranged along the light output direction of the light valve.

[0008] The refractive lens group includes a first lens group, a second lens group, and a third lens group arranged in sequence along the light output direction. The first lens group, the second lens group, and the third lens group satisfy 2 < |F2 / F1| < 12, 2 < |F3 / F1| < 15, and 1 < |F4 / F1| < 10, where 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, and an eighth lens arranged along the light exit direction. The second lens and the third lens form a first doublet lens, the fifth lens and the sixth lens form a second doublet lens, and the lenses in the first lens group are all spherical lenses.

[0010] Optionally, the refractive lens group and the reflective lens group satisfy 1.05 < L1 / L2 < 1.5, 0.05 < B / (L1 + L2) < 0.25, where L1 is the length of the refractive lens group, L2 is the distance between the refractive lens group and the reflective lens group, and B is the distance between the refractive lens group and the light valve.

[0011] Optionally, the projection lens further includes an aperture stop, and the aperture stop is located between the sixth lens and the seventh 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, and the eighth lens are positive, positive, negative, positive, negative, positive, positive, and negative in sequence.

[0013] Optionally, the refractive lens group and the reflective lens group further satisfy 0.1 < B / L2 < 0.35.

[0014] Optionally, the reflective lens group includes a curved mirror, and the curved mirror satisfies 32 mm ≤ (|R| * IC) / 17.65 ≤ 47 mm, -5 ≤ C ≤ 0, where R is the central curvature radius of the curved mirror, IC is the image circle size of the projection lens, and C is the conic coefficient of the curved mirror.

[0015] Optionally, the curved mirror is an aspherical concave mirror.

[0016] Optionally, the second lens group includes a ninth lens, and the third lens group includes a tenth lens, an eleventh lens, and a twelfth lens arranged along the light exit direction. The ninth lens, the tenth lens, and the eleventh lens are all spherical lenses, and the twelfth lens is an aspherical lens.

[0017] Optionally, the optical power of the second lens group is positive, the optical powers of the tenth lens, the eleventh lens, and the twelfth lens are positive, negative, and negative in sequence, and the optical powers of the refractive lens group and the reflective lens group are both positive.

[0018] According to another aspect of the present application, a projection device is provided, including the above projection lens.

[0019] The beneficial effects brought by the technical solution provided by the embodiments of the present application at least include:

[0020] A structure of a projection lens is provided. The first lens group therein includes eight spherical lenses. Four of the lenses respectively form two doublets in pairs, and the focal lengths of three lens groups in the refractive lens group satisfy corresponding proportional size relationships. Thus, the lens can achieve relatively high imaging requirements with a relatively small 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 that the number of lenses in the refractive lens group in the related art is relatively large, and thus it is difficult to reduce the volume of the lens. A projection lens with a relatively small volume is provided. Furthermore, the structure of the projection device applying the above projection lens can be correspondingly simplified, and the volume is conducive to compression. Description of the Drawings

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for description in the embodiments. Obviously, the following described drawings are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0022] Figure 1 It is a schematic diagram of the projection imaging process of a projection lens provided by the embodiments of the present application;

[0023] Figure 2 It is a schematic diagram of the structure of a projection lens shown in the embodiments of the present application;

[0024] Figure 3 It is a schematic diagram of the structure of another projection lens shown in the embodiments of the present application;

[0025] Figure 4 It is a schematic diagram of the structure of an optical engine provided by the embodiments of the present application;

[0026] Figure 5 It is a schematic diagram of the structure of a projection device provided by the embodiments of the present application.

[0027] Through the above drawings, the clear embodiments of the present application have been shown, and there will be more detailed descriptions hereinafter. These drawings and the text description are not intended to limit the scope of the concept of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. Detailed Embodiments

[0028] To make the objectives, technical solutions, and advantages of the present application clearer, the following will further describe the embodiments of the present application in detail in conjunction with the drawings.

[0029] Figure 1FIG. 0 is a schematic diagram of the projection imaging process of a projection lens provided by an embodiment of the present application. The implementation environment may include a projection screen 10 and a projection lens 20.

[0030] The projection lens 20 can project an image light beam onto the projection screen 10, and the image light 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. The projection distance s is the horizontal 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), and there is no need to reserve enough distance for imaging like a long focal length lens. The projection lens 20 can project a larger-sized image at a very short projection distance, and the projection device host and the screen also tend to be an integrated device. The projection lens with a relatively small projection ratio described above can be called a short focal length or ultra-short focal length projection lens.

[0031] However, various aberrations such as distortion (English: Distortion), astigmatism (English: Astigmatism), field curvature (English: Field Curvature), and coma (English: Coma) will occur in the projection lens with a relatively small projection ratio. To overcome these aberrations, the number of lenses in the projection lens in the related art is large (usually more than 16, about 20), the types are diverse, and a large number of doublets and triplets as well as a large number of aspherical lenses are used, which makes the system structure complex, the length of the system is not easy to reduce, the manufacturability is low, and the cost is difficult to control.

[0032] The embodiments of the present invention provide a projection lens and a projection device, which can solve the problems existing in the above related art.

[0033] Figure 2 FIG. 13 is a schematic structural diagram of a projection lens shown in 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 output direction f of the light valve.

[0034] The refractive lens group 21 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 f. The first lens group 211, the second lens group 212, and the third lens group 213 satisfy 2 < |F2 / F1| < 12, 2 < |F3 / F1| < 15, and 1 < |F4 / F1| < 10.

[0035] 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 reflective lens group 22.

[0036] The first lens group 211 includes a first lens t1, a second lens t2, a third lens t3, a fourth lens t4, a fifth lens t5, a sixth lens t6, a seventh lens t7, and an eighth lens t8 arranged along the light-emitting direction f. The second lens t2 and the third lens t3 form a first cemented doublet s1, and the fifth lens t5 and the sixth lens t6 form a second cemented doublet s2.

[0037] Among them, the lenses in the first lens group 211 are all spherical lenses.

[0038] A cemented doublet, also known as a doublet lens, is a lens obtained by gluing two lenses together. This combined lens formed by two lenses is an effective structure for achieving a short focal length, a large magnification, and good imaging quality.

[0039] In the first lens group 211, the first cemented doublet s1 near the light valve can be used to correct the astigmatism of the system (since the luminous object point is not on the optical axis of the optical system, the light beam it emits has an inclination angle with the optical axis. After the light beam is refracted by the lens, the convergence points of the meridional thin beam and the sagittal thin beam are not at the same point. That is, the light beam cannot be focused at a point, and the phenomenon of unclear imaging is called astigmatism.), the lateral chromatic aberration, and the coma (an imaging error of the optical system, which can refer to the fact that when a wide beam of light emitted from an off-axis object point passes through the optical system, it does not converge at a point, but forms a comet-shaped pattern relative to the principal ray, which is an asymmetric aberration). The second cemented doublet s2 near the aperture stop mainly corrects the spherical aberration and the field curvature of the system. Optionally, the refractive lens group 21 and the reflective lens group 22 satisfy 1.05 < L1 / L2 < 1.5, 0.05 < B / (L1 + L2) < 0.25, where L1 is the length of the refractive lens group 21, L2 is the distance between the refractive lens group 21 and the reflective lens group 22, and B is the distance between the refractive lens group 21 and the light valve 31.

[0040] In the embodiments of the present application, the distance between the refractive lens group and the light valve can be called the back working distance, and this distance can be relatively short. For example, it can be 15.625 mm to 16.34 mm. The overall length of the projection lens can also be relatively short, such as 171.209 mm.

[0041] Optionally, the refractive lens group 21 and the reflective lens group 22 also satisfy 0.1 < B / L2 < 0.35. The reflective lens group includes a curved mirror, and the curved mirror satisfies 32 mm ≤ (|R| * IC) / 17.65 ≤ 47 mm, -5 ≤ C ≤ 0, where R is the radius of curvature of the center of the curved mirror, IC is the size of the image circle of the projection lens (the image circle is the clear range of the maximum image on the light valve plane), and C is the conic coefficient of the curved mirror.

[0042] It should be noted that the light valve 31 may not be included in the projection lens provided in the embodiments of the present application.

[0043] In summary, in the projection lens provided in the embodiments of the present application, the first lens group includes eight spherical lenses. The second lens and the third lens among these eight lenses form a doublet lens, and the fifth lens and the sixth lens form another doublet lens. By cooperating these two doublet lenses with other lenses and making the focal lengths of the three lens groups in the refractive lens group satisfy the corresponding proportional size relationship, the lens can achieve high imaging requirements with a relatively small 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 that the number of lenses in the refractive lens group in the related art is large, and thus it is difficult to reduce the volume of the lens, provides a projection lens with a relatively small size, and the structure of the projection device applying the above projection lens can also be simplified accordingly, and the volume is conducive to compression.

[0044] Optionally, the projection lens further includes an aperture stop, and the aperture stop is located between the sixth lens and the seventh lens of the first lens group.

[0045] 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, and the eighth lens are positive, positive, negative, positive, negative, positive, positive, and negative in sequence.

[0046] Optionally, the refractive lens group and the reflective lens group further satisfy 0.1 < B / L2 < 0.35.

[0047] Optionally, the reflective lens group includes a curved mirror, and the curved mirror satisfies 32 mm ≤ (|R| * IC) / 17.65 ≤ 47 mm, -5 ≤ C ≤ 0, where R is the center curvature radius of the curved mirror, IC is the image circle size of the projection lens, and C is the conic coefficient of the curved mirror.

[0048] Optionally, the curved mirror is an aspherical concave mirror.

[0049] Optionally, the second lens group includes a ninth lens, and the third lens group includes a tenth lens, an eleventh lens, and a twelfth lens arranged along the light output direction. The ninth lens, the tenth lens, and the eleventh lens are all spherical lenses, and the twelfth lens is an aspherical lens.

[0050] Optionally, the optical power of the second lens group is positive, the optical powers of the tenth lens, the eleventh lens, and the twelfth lens are positive, negative, and negative in sequence, and the optical powers of the refractive lens group and the reflective lens group are both positive.

[0051] Figure 3 is a schematic structural diagram of another projection lens shown in the embodiments of the present application. This projection lens is at Figure 2Some adjustments have been made based on the projection lens shown.

[0052] Optionally, the projection lens 20 further includes an aperture diaphragm 23, which is located between the sixth lens t6 and the seventh lens t7 of the first lens group 211. The aperture diaphragm 23 can control aberration correction and the entrance pupil diameter.

[0053] The focal power of the lenses in the optical system (the focal power is equal to the difference between the convergence of the image-side light beam and the convergence of the object-side light beam, and it characterizes the ability of the optical system to deflect light rays) will directly affect astigmatism, field curvature, distortion, axial chromatic aberration, and lateral chromatic aberration. Therefore, different combinations of positive and negative focal powers will also play a certain role in aberration correction. In an exemplary embodiment, the focal powers of the first lens t1, the second lens t2, the third lens t3, the fourth lens t4, the fifth lens t5, the sixth lens t6, the seventh lens t7, and the eighth lens t8 are positive, positive, negative, positive, negative, positive, positive, and negative in sequence.

[0054] Optionally, the second lens group 212 includes a ninth lens t9, and the third lens group 213 includes the tenth lens t10, the eleventh lens t11, and the twelfth lens t12 arranged along the light exit direction f. The ninth lens t9, the tenth lens t10, and the eleventh lens t11 are all spherical lenses, and the twelfth lens t12 is an aspherical lens (for example, it can be a rotationally symmetric aspherical lens). The twelfth lens t12 as an aspherical lens can be used to correct the distortion and field curvature of the system.

[0055] The twelfth lens t12 is made of 330R material (an optical material) and can be processed by a molding method.

[0056] Optionally, the focal power of the second lens group 212 is positive, the focal powers of the tenth lens t10, the eleventh lens t11, and the twelfth lens t12 are positive, negative, and negative in sequence, and the focal powers of the refractive lens group 21 and the reflective lens group 22 are both positive.

[0057] Optionally, the reflective lens group 22 includes an aspherical concave mirror for reflecting the outgoing light of the projection lens onto the screen for imaging. The aspherical concave mirror can be an axially symmetric aspherical concave mirror. The aspherical concave mirror can satisfy 32 mm ≤ (|R| * IC) / 17.65 ≤ 47 mm, -5 ≤ C ≤ 0, where R is the central curvature radius of the curved mirror, IC is the image circle size of the projection lens, and C is the conic coefficient of the curved mirror.

[0058] In this embodiment, the effective focal length (EFL) of the projection lens is 1.963 millimeters (mm), the resolution is 117 lp / mm (lines per millimeter), and the projected image is 60 inches.

[0059] For the projection lens provided in the embodiment of the present application, the number of lenses is small, less than 14, and the number of aspherical lenses is also small, greatly reducing the complexity and volume of the projection lens. In addition, the aspherical lens uses 330R plastic material, which has low cost and is easy to process (manufactured by molding). Therefore, the projection lens has been greatly improved in terms of volume, complexity, cost, and processability. It should be noted that the aspherical lens can also use plastic materials such as 480R and K26R, and the embodiments of the present application do not limit this.

[0060] In the embodiment of the present application, the first lens group and the second lens group are movable lens groups, that is, these two lens groups can move along the optical axis direction to perform operations such as focusing or adjusting the focal length. In addition, the third lens group and the reflector group are also lens groups that can be finely adjusted to cooperate with the first lens group and the second lens group for adjustment.

[0061] The projection lens provided in the embodiment of the present application can be an ultra-short focal length projection lens. The structure of this ultra-short focal length projection lens is compact. While achieving high-resolution imaging quality through the diaphragm, aspherical lens, cemented lens, reflector, and reasonable material combination, it has also been greatly improved in terms of the volume, cost, and processability of the lens.

[0062] In summary, in the projection lens provided in the embodiment of the present application, the first lens group includes eight spherical lenses, and four of them form two doublet projections respectively in pairs, and the focal lengths of the three lens groups in the refractive lens group satisfy the corresponding proportional size relationship, so that the lens can 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 that the number of lenses in the refractive lens group in the related art is large, and it is difficult to reduce the volume of the lens, provides a projection lens with a smaller volume, and the structure of the projection device using the above projection lens can also be simplified accordingly, and the volume is conducive to compression.

[0063] Figure 4 It is a schematic structural diagram of an optical engine provided in the 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, and Figure 3 the projection lens shown.

[0064] Optionally, the light valve 51 can be a 0.37-inch Liquid Crystal on Silicon (LCOS) light valve. Liquid Crystal on Silicon is a matrix liquid crystal display component based on the reflection mode with a very small size. This matrix is fabricated on a silicon chip using Complementary Metal Oxide Semiconductor (CMOS) technology. Liquid Crystal on Silicon adopts the reflection projection method, and the light utilization efficiency can reach more than 40%. Moreover, its greatest advantage is that it can be produced by the widely used and low-cost CMOS manufacturing technology without additional investment, and can be gradually miniaturized with the semiconductor manufacturing process to improve the resolution. The 0.37-inch Liquid Crystal on Silicon light valve can provide a 1080p image screen.

[0065] The polarization beam splitter prism 52 is located between the light valve 51 and the projection lens 20 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.

[0066] Among them, the light source device 54 can include various components such as a laser light source 541, a light adjustment component 542, and a light homogenizing component 543.

[0067] 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. Alternatively, the laser light source 541 can also provide two-color laser light to improve the imaging quality of the optical engine.

[0068] Compared with the light-emitting diode light source, the laser light source has the advantages of high brightness, good monochromaticity, and good directivity.

[0069] Optionally, the light homogenizing device 543 includes a light guide tube. The light guide tube is a tubular device formed by splicing four planar reflector sheets, that is, a hollow light guide tube. The light is reflected multiple times inside the light guide tube to achieve the effect of light homogenization. The light guide tube can also adopt a solid light guide tube. The light input port and the light output port of the light guide tube are rectangles with the same shape and area. The laser beam enters from the light input port of the light guide tube and then shoots from the light output port of the light guide tube towards the light valve assembly, and the beam homogenization and spot optimization are completed during the process of passing through the light guide tube.

[0070] In addition, the light homogenizing device 543 may also include a compound eye lens, which is usually formed by combining a series of small lenses. Two arrays of compound eye lenses are arranged in parallel to split the spot of the input laser beam, and then the split spots are accumulated through subsequent focusing lenses, so as to achieve beam homogenization and spot optimization. In an illumination device, the light homogenizing device 543 may select at least one of a light guide tube or a compound eye lens, and the embodiments of the present application do not limit this here.

[0071] In the embodiments of the present application, a liquid crystal on silicon (LCoS) light valve based on 0.37 inches is provided, which is combined with an ultra-short-focus projection lens to be able to project an image screen with a resolution of 1080p on a screen. In addition, the projection lens may have two different structures, and the number of lenses is small, both less than 14, and the number of aspherical lenses is also small, greatly reducing the complexity and volume of the projection lens. In addition, the aspherical lens may be made of 330R plastic material, which has low cost and is easy to process (manufactured by molding), so the projection lens has been greatly improved in terms of volume, complexity, cost and processing. It should be noted that the aspherical lens may also be made of plastic materials such as 480R and K26R, and the embodiments of the present application do not limit this.

[0072] In the projection imaging system of this embodiment, the offset of the pixel plane of the light valve 51 relative to the optical axis satisfies the relationship: 135% < offset < 150%.

[0073] In the projection imaging system of this embodiment, the linear relationship (i.e., the projection ratio) between the straight-line distance from the mirror group to the screen and the length of the projection screen satisfies: projection distance / screen length dimension ≤ 0.24.

[0074] The projection lens provided by the present application may be a secondary imaging architecture, with the pixel plane of the light valve as the object plane. After the light beam emitted from the light valve passes through the refractive lens group, the first imaging is performed between the mirror group and the refractive lens group (when the light beam forms a convergence point once, it is the first imaging). After the first imaging is reflected by the mirror group, a secondary distortion-free image is formed on the screen, and the secondary imaging is performed, and a large-size projection image is displayed on the projection screen.

[0075] When the size of the image screen projected by the optical engine provided by the embodiments of the present application on the screen is 60 inches (1328x747mm 2 ), the maximum value of the TV distortion is -0.2009%.

[0076] Optionally, the optical engine may further include a galvanometer, which is located between the polarization beam splitter prism 52 and the projection lens 20 and is used to offset the image beam by vibrating, thereby improving the resolution of the image screen projected onto the screen.

[0077] The galvanometer mirror vibrates, causing the imaging light beams corresponding to two adjacent frames of projection images passing through the vibrating lens not to completely overlap. The imaging light beams corresponding to two adjacent frames of projection images are sequentially projected onto the refractive lens group. The projection image is the image presented on the projection screen after the imaging light beam passes through the projection lens.

[0078] Exemplarily, the galvanometer mirror includes a flat glass and a driving component. The flat glass can vibrate under the drive of the driving component. The vibration of the flat glass causes the imaging light beams corresponding to two adjacent frames of projection images passing through the flat glass not to completely overlap, increasing the imaging light beams incident on the same pixel, thereby improving the imaging resolution. Moreover, due to the vibration of the flat glass, the imaging light beams corresponding to two adjacent frames of projection images are slightly staggered, making the transition between pixels smoother, thus increasing the details of the picture and visually improving the clarity of the picture, and further improving the imaging quality. Utilizing the effect of the human eye's visual persistence, for the user, the viewed picture achieves an increase in resolution, having an effect of "doubling" the resolution.

[0079] When the flat glass vibrates frequently between two positions, two sub-images are superimposed with dislocation. When the flat glass vibrates frequently between four positions, four sub-images are superimposed with dislocation to achieve a two-fold or four-fold increase in resolution in terms of visual effect.

[0080] Exemplarily, when the light beam incident on the galvanometer mirror is a parallel light beam (i.e., the incident angle of each light ray in the light beam is the same), after the optical lens in the galvanometer mirror swings from one position to another position, the displacement distance of each pixel of the projection image corresponding to the imaging light beam is equal, making the offset amount from each field of view in the projection lens to the projection screen consistent, which can ensure high-resolution display of the visual picture. Herein, the offset amount of the field of view refers to the actual displacement distance of the field of view.

[0081] In the optical engine provided by the embodiment of the present application, there is a 0.37-inch light valve. The light valve itself can provide an imaging picture with a resolution of 1080p. After the 0.37-inch light valve is combined with the galvanometer mirror, it can further provide an imaging picture with a resolution of 2k or 4k, greatly improving the display effect.

[0082] In summary, for the optical engine provided in the embodiments of the present application, by making the refractive lens group and the reflective lens group satisfy the corresponding distance parameter range, and making the focal lengths of the three lens groups in the refractive lens group satisfy the corresponding proportional size relationship, the lens can meet high imaging requirements with a relatively small size. Compared with the refractive lens group composed of a large number of lenses in the related art, the size of the lens can be smaller. This solves the problem in the related art that the number of lenses in the refractive lens group is large, making it difficult to reduce the volume of the lens, provides a projection lens with a relatively small volume, and the structure of the projection device using the above projection lens can be correspondingly simplified, facilitating volume compression.

[0083] Currently, most projection devices have a display resolution of 720P and mostly adopt a light-emitting diode (LED) light source to achieve a small-size design. However, due to the difficulty in obtaining high brightness with the performance of the LED light source, there are few micro-projection products with high resolution, high brightness, and small size in the market. As one of the core technologies of projection display, the design and processing of lenses are both difficult to some extent. Especially, it is a major challenge in lens design to balance cost and miniaturization while ensuring image quality.

[0084] In the embodiments of the present application, a light valve based on 0.37-inch liquid crystal on silicon is provided, which, in cooperation with an ultra-short-focus projection lens, can project an image with a resolution of 1080p onto a screen. In addition, the number of lenses in this projection lens is small, all less than 14, and the number of aspherical lenses is also small, greatly reducing the complexity and volume of the projection lens. In addition, the aspherical lens uses 330R plastic material, which has low cost and is easy to process (manufactured by molding). Therefore, this projection lens has been greatly improved in terms of volume, complexity, cost, and processing. In addition, this projection lens can use a laser light source, which can greatly improve the brightness of the image.

[0085] As Figure 5 shown, the embodiments of the present application also provide a laser projection device, including a screen 60 and Figure 4 the optical engine 50 as shown. The optical engine 50 may include the lens 20 provided in the above Figure 3 shown embodiments.

[0086] When the laser projection device is operating, the light beam emitted by the light source device 54 is directed towards the light valve 51. The outgoing light beam of the light valve 51 is directed towards the polarization beam splitter prism 52 and then, via the polarization beam splitter prism 52, towards the lens 20. After the lens 20 adjusts the light beam, it is directed towards the screen 60, and an image is formed on the screen 60.

[0087] The laser projection device provided in the above embodiments adopts a telecentric system. The light valve projects into the projection lens with parallel light beams. A total reflection prism is also provided between the light valve and the projection lens, or a vibrating lens is further provided. Thus, on the premise of reserving sufficient back focal distance, the projection lens can also optimize the number of lenses through reasonable combination of lens groups. The first lens group is set as a combination of a spherical lens and two doublets to correct the primary aberration, reduce the imaging burden of the rear-end lenses, and facilitate the simplification of the rear-end lenses. In addition, by setting the aperture stop in the first lens group, the system aperture can be better controlled, which is also beneficial to the correction of aberration.

[0088] In addition, in the above-mentioned multiple examples, by setting the first lens group and the second lens group as movable groups, and by means of fine-tuning the distance between the reflecting mirror and the third lens group, the adjustment of the projection size under the requirements of ultra-short focal length and high definition projection can be realized, meeting a wider range of projection requirements.

[0089] In this application, the terms "first", "second", "third", "fourth", ······ "twelfth", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. The term "plurality" means two or more, unless otherwise clearly defined.

[0090] The above are only optional embodiments of this application and are not intended to limit this application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application shall be included within the protection scope of this application.

Claims

1. A projection lens, characterized in that, The projection lens includes a refractive lens group and a reflective lens group arranged along the light-emitting direction of the light valve; The refractive lens group is composed of 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 satisfy 2 < |F2 / F1| < 12, 2 < |F3 / F1| < 15, and 1 < |F4 / F1| < 10, where 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 is composed of a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens arranged along the light-emitting direction. The second lens and the third lens form a first doublet lens, the fifth lens and the sixth lens form a second doublet lens, and the lenses in the first lens group are all spherical lenses; 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, and the eighth lens are positive, positive, negative, positive, negative, positive, positive, and negative in sequence; The second lens group is composed of a ninth lens, and the optical power of the ninth lens is positive; The third lens group is composed of a tenth lens, an eleventh lens, and a twelfth lens arranged along the light-emitting direction. The ninth lens, the tenth lens, and the eleventh lens are all spherical lenses, and the twelfth lens is an aspherical lens. The optical powers of the tenth lens, the eleventh lens, and the twelfth lens are positive, negative, and negative in sequence; Among them, the refractive lens group and the reflective lens group satisfy 1.05 < L1 / L2 < 1.5, 0.05 < B / (L1 + L2) < 0.25, where L1 is the length of the refractive lens group, L2 is the distance between the refractive lens group and the reflective lens group, B is the distance between the refractive lens group and the light valve, and the optical powers of both the refractive lens group and the reflective lens group are positive.

2. The projection lens according to claim 1, characterized in that, The projection lens further includes an aperture stop, and the aperture stop is located between the sixth lens and the seventh lens of the first lens group.

3. The projection lens according to any one of claims 1-2, characterized in that, The refractive lens group and the reflective lens group further satisfy 0.1 < B / L2 < 0.

35.

4. The projection lens according to claim 3, characterized in that, The reflective lens group includes a curved mirror, and the curved mirror satisfies 32 mm ≤ (|R| * IC) / 17.65 ≤ 47 mm, -5 ≤ C ≤ 0, where R is the central curvature radius of the curved mirror, IC is the image circle size of the projection lens, and C is the conic coefficient of the curved mirror.

5. The projection lens according to claim 4, characterized in that, The curved mirror is an aspherical concave mirror.

6. A projection device, characterized in that, Including the projection lens according to any one of claims 1-5.

Images