CN114545588A

CN114545588A - Projection lens and projection equipment

Info

Publication number: CN114545588A
Application number: CN202011354024.9A
Authority: CN
Inventors: 阴亮; 杜玉楠
Original assignee: Qingdao Hisense Laser Display Co Ltd
Current assignee: Qingdao Hisense Laser Display Co Ltd
Priority date: 2020-11-26
Filing date: 2020-11-26
Publication date: 2022-05-27

Abstract

The application discloses projection lens and projection equipment belongs to projection technical field. The projection lens comprises a refraction lens group and a reflection lens group which are arranged along the light-emitting direction of the light valve; the refracting lens group comprises a first lens group, a second lens group and a third lens group which are sequentially arranged along the light emitting direction, and the first lens group, the second lens group and the third lens group satisfy 2 < | F₂/F₁|＜12，2＜|F₃/F₁And | <15, the first lens group comprises eight spherical lenses arranged along the light-emitting direction, wherein the eight spherical lenses comprise two double-cemented lenses formed by four transparent lenses. The application provides a structure of a projection lens, and the focal lengths of three lens groups in a refraction lens group meet the corresponding proportional size relationship, so that the projection lens can use one lens groupSmaller sizes can achieve higher imaging requirements. The problem that the size of a lens is difficult to reduce in the related art is solved, and the projection lens with the smaller size is provided.

Description

Projection lens and projection equipment

Technical Field

The application relates to the technical field of projection, in particular to a projection lens and projection equipment.

Background

With the improvement of scientific technology, with the application of household projection equipment, such as laser ultra-short-focus projection equipment, a picture with large size, high definition, high color gamut range and brightness can be presented to a user in a wall-attached state, wherein the high-quality picture is presented not only because laser is applied as a light source, but also an ultra-short-focus lens with high resolution capability is an important component of the laser projection equipment. The higher the resolving power of the projection lens is, the higher the user viewing experience is.

In the process of designing the lens, various requirements need to be considered. For example, the projection lens needs to be designed in cooperation with an illumination system, the illumination system is divided into a telecentric illumination system and a non-telecentric illumination system, the projection lens is correspondingly designed into a telecentric projection lens and a non-telecentric projection lens, and the receiving and constraint capacities of light beams are different.

In addition, the increase of the resolving power of the projection lens generally increases the number of lenses used, and the design difficulty of the lens surface type is higher.

That is, the combination of lenses in a projection lens is generally complicated to achieve higher resolution and shorter focal length. Further, the overall structure of the projection lens is complex, which is not favorable for reducing the volume of the lens, and the volume of the projection lens occupies more than one third of the optical engine of the projection device, which also makes the volume of the whole laser projection device difficult to reduce, making the device bulky.

Disclosure of Invention

The embodiment of the application provides a projection lens and projection equipment. The technical scheme is as follows:

according to an aspect of the present application, there is provided a projection lens, comprising a refractive lens group and a reflective lens group arranged along a light exit direction of a light valve;

the refracting mirror group includes follows first mirror group, second mirror group and third mirror group that the light-emitting direction set gradually, first mirror group the second mirror group with the third mirror group satisfies 2 < | F₂/F₁|＜12，2＜|F₃/F₁<15 and 1 < | F₄/F₁< 10, the F1 is an equivalent focal length of the projection lens, the F2 is an equivalent focal length of the first lens group, the F3 is an equivalent focal length of the second lens group, and the F4 is an equivalent focal length of the third lens group;

the first mirror group comprises 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 which are arranged along the light emitting direction, the second lens and the third lens form a first double cemented lens, the fifth lens and the sixth lens form a second double cemented lens, and the lenses in the first mirror group are spherical lenses.

Optionally, the refractor set and the reflector set satisfy 1.05 < L₁/L₂＜1.5，0.05＜B/(L₁+L₂) < 0.25, said L₁Is the length of said refractive lens group, said L₂The distance between the refractor set and the reflector set is defined, and the distance between the refractor set and the light valve is defined as B.

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.

Optionally, the focal 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, negative, positive and negative in sequence.

Optionally, the refractive and reflective mirror groups further satisfy 0.1<B/L₂<0.35。

Optionally, the mirror group includes a curved mirror, and the curved mirror satisfies that | R | IC)/17.65 | -47 mm, -5 | ≦ C, where R is a central curvature radius of the curved mirror, IC is an image circle size of the projection lens, and C is a cone coefficient of the curved mirror.

Optionally, the curved surface reflector is an aspheric concave surface reflector.

Optionally, the second lens group includes a ninth lens, 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 aspheric lens.

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

According to another aspect of the application, a projection device is provided, which comprises the projection lens.

The beneficial effects brought by the technical scheme provided by the embodiment of the application at least comprise:

the utility model provides a structure of projection lens, wherein first group of lens includes eight spherical lens, and two double-cemented projections that constitute of four lens wherein to make the focus of three group of lens in the refraction mirror group satisfy corresponding proportional size relation, and then make this camera lens can realize higher formation of image requirement with a less size, compare in the refraction mirror group that many lenses constitute among the correlation technique, the size of camera lens can be less. The problem of among the correlation technique the lens of refractor group be more, and then the camera lens volume is difficult to reduce is solved, a less projection lens is provided, and then the projection equipment structure of using above-mentioned projection lens also can simplify correspondingly, and the volume does benefit to the compression.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a schematic diagram of a projection imaging process of a projection lens provided in an embodiment of the present application;

fig. 2 is a schematic structural diagram of a projection lens according to an embodiment of the present application;

fig. 3 is a schematic structural diagram of another projection lens according to an embodiment of the present disclosure;

FIG. 4 is a schematic structural diagram of an optical engine according to an embodiment of the present disclosure;

fig. 5 is a schematic structural diagram of a projection apparatus according to an embodiment of the present application.

With the above figures, there are shown specific embodiments of the present application, which will be described in more detail below. These drawings and written description are not intended to limit the scope of the inventive concepts in any manner, but rather to illustrate the inventive concepts to those skilled in the art by reference to specific embodiments.

Detailed Description

To make the objects, technical solutions and advantages of the present application more clear, embodiments of the present application will be described in further detail below with reference to the accompanying drawings.

Fig. 1 is a schematic diagram of a projection imaging process of a projection lens provided in an embodiment of the present application, and the implementation environment may include a projection screen 10 and a projection lens 20.

The projection lens 20 may project an image beam toward the projection screen 10, which is capable of forming an image on the screen 10. The current trend is to reduce the throw ratio of the projection lens 20 (the throw ratio is the ratio of the projection distance s to the diagonal length h of the picture, and the projection distance s is the transverse distance between the projection lens 20 and the projection screen 10), the smaller the throw ratio, the closer the laser projection device can be arranged to the wall (the plane where the projection screen is located), and it is not necessary to reserve enough distance to image like a telephoto lens, and the projection lens 20 can project the picture with larger size within a short projection distance, and the projection device host and the screen tend to be an integrated device. The projection lens having a relatively small projection ratio may be referred to as a short-focus or ultra-short-focus projection lens.

However, a projection lens with a relatively small projection ratio may have various aberrations such as Distortion (aberration), Astigmatism (Astigmatism), Field Curvature (Field Curvature), and Coma (Coma). In order to overcome these aberrations, the projection lens in the related art has a large number of lenses (usually more than 16, about 20 lenses), a large number of types, and a large number of bi-cemented and tri-cemented lenses and a large number of aspheric lenses, thereby making the system structure complicated, the length of the system also not easy to shrink, the manufacturability is low, and the cost is difficult to control.

The embodiment of the invention provides a projection lens and a projection device, which can solve the problems in the related art.

Fig. 2 is a schematic structural diagram of a projection lens according to 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 exit direction f of the light valve.

The refractive lens group 21 includes a first lens group 211, a second lens group 212 and a third lens group 213 sequentially arranged along the light emitting direction F, wherein 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。

Wherein F1 is the equivalent focal length of the projection lens assembly 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.

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 which are arranged along the light exit 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 s 2.

The lenses in the first lens group 211 are all spherical lenses.

A double cemented lens (also called a double-cemented lens) is a lens obtained by cementing two lenses together. The combined lens formed by two lenses is an effective structure for achieving short focal length, large magnification and better imaging quality.

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 (because the object point of the light is not on the optical axis of the optical system, the light beam emitted by the light valve has an oblique angle with respect to the optical axisThe phenomenon of inability to focus at one point and imaging ambiguity is called astigmatism. ) Correcting vertical axis chromatic aberration and coma aberration (an imaging error of an optical system, which can be an asymmetric aberration that a wide light beam emitted by an object point outside an optical axis passes through the optical system, does not converge and is in a comet-shaped pattern relative to a main light ray); the second doublet lens s2 near the aperture stop mainly corrects the spherical aberration and curvature of field of the system. Optionally, the refractive optical elements 21 and the reflective optical elements 22 satisfy 1.05 < L₁/L₂＜1.5，0.05＜B/(L1+L2)＜0.25，L₁Is the length, L, of the refractive optical element 21₂Is the distance between the refractive optical element 21 and the reflective optical element 22, and B is the distance between the refractive optical element 21 and the light valve 31.

In the embodiment of the present application, the distance between the refractive lens group and the light valve may be referred to as a rear working distance, and the distance may be relatively short, for example, 15.625 mm to 16.34 mm. The total length of the projection lens may also be short, such as 171.209 mm.

Optionally, the refractive lens group 21 and the reflective lens group 22 further satisfy 0.1<B/L₂<0.35, the reflector group comprises a curved surface reflector, the curved surface reflector satisfies the conditions that | R | + -IC)/17.65 is less than or equal to 47mm, C is less than or equal to 5 and less than or equal to 0, R is the central curvature radius of the curved surface reflector, IC is the size of an image circle (the image circle is the clear range of the maximum image of the lens on a light valve plane) of the projection lens, and C is the cone coefficient (Conic) of the curved surface reflector.

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

To sum up, in the projection lens provided in the embodiment of the present application, the first lens group includes eight spherical lenses, the second lens and the third lens in these eight lenses constitute a double cemented lens, the fifth lens and the sixth lens constitute another second double cemented lens, and the two double cemented lenses are matched with other lenses, so that the focal lengths of the three lens groups in the refractive lens group satisfy the corresponding proportional size relationship, and further the lens can realize higher imaging requirements with a smaller size. The problem of among the correlation technique the lens quantity of refractor group is more, and then the camera lens volume is difficult to reduce is solved, a less projection lens of volume is provided to and the projection equipment structure of using above-mentioned projection lens also can simplify correspondingly, and the volume does benefit to the compression.

Optionally, the mirror group comprises a curved mirror, and the curved mirror satisfies 32 mm ≦ (| R |) IC)/17.65 ≦ 47mm, -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 cone coefficient of the curved mirror.

Optionally, the curved mirror is an aspheric concave mirror.

Optionally, the second lens group includes a ninth lens, 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 aspheric lens.

Fig. 3 is a schematic structural diagram of another projection lens according to an embodiment of the present application, in which some adjustments are performed on the projection lens shown in fig. 2.

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

The focal power of the lens in the optical system (focal power, which is equal to the difference between the convergence of the image beam and the convergence of the object beam and represents the capability of the optical system to deflect the light) directly affects astigmatism, curvature of field, distortion, axial chromatic aberration and vertical axis chromatic aberration, so that different positive and negative focal power combinations also play a role in aberration correction. In an exemplary embodiment, the optical 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, negative, positive and negative in sequence.

Optionally, the second lens group 212 includes a ninth lens t9, the third lens group 213 includes a tenth lens t10, an eleventh lens t11 and a 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 aspheric lens (for example, may be a rotationally symmetric aspheric lens). The twelfth lens t12, which is an aspherical lens, may be used to correct distortion of the system, and curvature of field.

The twelfth lens t12 is made of 330R material (an optical material) and can be formed by a molding process.

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

Optionally, the mirror group 22 includes an aspheric concave mirror for reflecting the light emitted from the projection lens to the screen for imaging. The aspheric concave mirror may be an axisymmetric aspheric concave mirror. The aspheric concave reflector can meet the requirements that | R | IC)/17.65 | -47 mm is more than or equal to 32 mm, C is more than or equal to 5 and less than or equal to 0, R is the central curvature radius of the curved reflector, IC is the image circle size of the projection lens, and C is the cone coefficient of the curved reflector.

In this embodiment, the Effective Focal Length (EFL) of the projection lens is 1.963 millimeters (mm), the resolution is 117lp/mm (line pair/mm), and the projection screen is 60 inches.

The projection lens that this application embodiment provided, the quantity of lens is less, is less than 14, and the quantity of aspheric surface lens is also less, has reduced projection lens's complexity and volume greatly, and in addition, the aspheric surface lens adopts 330R plastic material, and is with low costs and easily process (make through the mode of mould pressing), therefore this projection lens all has very big promotion from volume, complexity, cost and processing aspect. The aspherical mirror may be made of a plastic material such as 480R, K26R, which is not limited in the embodiments of the present application.

In the embodiment of the present application, the first lens group and the second lens group are movable lens groups, that is, the 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 lens group are also micro-adjustable lens groups to be matched with the first lens group and the second lens group for adjustment.

The projection lens provided by the embodiment of the application can be an ultra-short-focus projection lens. The ultra-short-focus projection lens is compact in structure, high-resolution imaging quality is achieved through the diaphragm, the aspheric lens, the cemented lens, the reflector and reasonable material matching, and meanwhile the size, cost and machinability of the lens are greatly improved.

To sum up, in the projection lens provided in the embodiment of the present application, the first lens group includes eight spherical lenses, two of the four spherical lenses constitute two double-cemented projections respectively, 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 realize a higher imaging requirement with a smaller size, and compared with a refractive lens group constituted by more lenses in the related art, the size of the lens can be smaller. The problem of among the correlation technique the lens quantity of refractor group is more, and then the camera lens volume is difficult to reduce is solved, a less projection lens of volume is provided to and the projection equipment structure of using above-mentioned projection lens also can simplify correspondingly, and the volume does benefit to the compression.

Fig. 4 is a schematic structural diagram of an optical engine 50 according to an embodiment of the present disclosure, where the optical engine includes a light source device 54, a light valve 51, a polarization splitting prism 52, and the projection lens shown in fig. 3.

Alternatively, the light valve 51 may be a 0.37 inch Liquid Crystal On Silicon (LCOS) light valve. Liquid crystal on silicon is a matrix liquid crystal display element based on the reflective mode, which is very small in size. The matrix is fabricated on a silicon chip using Complementary Metal Oxide Semiconductor (CMOS) technology. The silicon-based liquid crystal adopts a reflective projection mode, the light utilization efficiency can reach more than 40 percent, and the silicon-based liquid crystal has the greatest advantages that the silicon-based liquid crystal can be produced by the widely used CMOS manufacturing technology with lower cost, does not need additional investment, and can be rapidly micronized along with the semiconductor manufacturing process to gradually improve the resolution. While a 0.37 inch LCOS light valve can provide 1080p image.

A polarizing beam splitter prism 52 is positioned between the light valve 51 and the projection lens 20 for separating the illumination beam and the imaging beam. The polarization beam splitter prism 52 may be a Total Internal Reflection (TIR) prism or a Reverse Total Internal Reflection (RTIR) prism.

The light source device 54 may include various components such as a laser light source 541, a light adjusting component 542, and a light uniformizing component 543.

The laser light source 541 is configured to provide laser light, and the light adjustment component 542 is configured to adjust the laser light provided by the laser light source 541 into primary color light and output the primary color light. For example, if the laser light source 541 provides blue laser light, the light adjustment assembly 542 may adjust the blue laser light to blue laser light, red laser light, and green laser light. Alternatively, the laser light source 541 may provide laser light of two colors to improve the quality of the image formed by the optical engine.

Compared with a light emitting diode light source, the laser light source has the advantages of high brightness, good monochromaticity and good directivity.

Optionally, the light homogenizing device 543 includes a light guide tube, the light guide tube is a tubular device formed by splicing four plane reflection sheets, that is, a hollow light guide tube, light is reflected multiple times inside the light guide tube to achieve the light homogenizing effect, the light guide tube may also be a solid light guide tube, the light inlet and the light outlet of the light guide tube are rectangles with uniform shapes and areas, the laser beam enters from the light inlet of the light guide tube and then emits to the light valve assembly from the light outlet of the light guide tube, and beam homogenization and light spot optimization are completed in the process of passing through the light guide tube.

In addition, the light homogenizing device 543 may also include a fly-eye lens, which is usually formed by combining a series of small lenses, two rows of fly-eye lens arrays are arranged in parallel to divide the light spots of the input laser beam, and the divided light spots are added by a subsequent focusing lens, so as to homogenize the light beam and optimize the light spots. In an illumination apparatus, the light uniformizing device 543 may select at least one of a light pipe and a fly eye lens, and the embodiment of the present application is not limited herein.

In the embodiment of the application, a light valve based on 0.37 inch liquid crystal on silicon is provided, and an ultra-short-focus projection lens is matched, so that an image picture with a resolution of 1080p can be projected on a screen. In addition, the projection lens can have two different structures, the number of the lenses is less than 14, the number of the aspheric lenses is also less, the complexity and the volume of the projection lens are greatly reduced, in addition, the aspheric lenses can be made of 330R plastic materials, the cost is low, and the processing is easy (the aspheric lenses are manufactured in a die pressing mode), so that the volume, the complexity, the cost and the processing of the projection lens are greatly improved. The aspherical mirror may be made of a plastic material such as 480R, K26R, which is not limited in the embodiments of the present application.

The offset of the pixel surface of the light valve 51 in the projection imaging system of the present embodiment with respect to the optical axis satisfies the following relation: 135% < offset < 150%.

The linear relation (namely the projection ratio) between the linear distance between the reflector group and the screen and the length of the projection picture of the projection imaging system of the embodiment meets the following requirements: the projection distance/screen length size is less than or equal to 0.24.

The projection lens provided by the application can be a secondary imaging framework, the pixel surface of the light valve is an object surface, light valve emergent light beams pass through the refraction mirror group, primary imaging is carried out between the reflection mirror group and the refraction mirror group (light beam forming convergence points are primary imaging), secondary undistorted images are formed on a screen after the primary imaging is reflected by the reflection mirror group, secondary imaging is carried out, and large-size projection images are displayed on the projection screen.

In the optical engine provided in the embodiment of the present application, the size of the image projected on the screen is 60 inches (1328 × 747 mm)²) Its TV distortion maximum is-0.2009%.

Optionally, the optical engine may further include a vibrating mirror, which is located between the polarization splitting prism 52 and the projection lens 20 and is configured to shift the image beam by vibration, so as to improve the resolution of the image frame projected onto the screen.

The vibrating mirror vibrates to enable image light beams corresponding to two adjacent frames of projected images passing through the vibrating lens to be not completely overlapped, the image light beams corresponding to the two adjacent frames of projected images are sequentially emitted to the refraction mirror group, and the projected images are images displayed on a projection screen after the image light beams pass through the projection lens.

Illustratively, the galvanometer comprises a flat glass and a driving component, the flat glass can vibrate under the driving of the driving component, the vibration of the flat glass enables image light beams corresponding to two adjacent frames of projection images passing through the flat glass to be not completely overlapped, the image light beams emitted to the same pixel are increased, and then the imaging resolution is improved.

When the plate glass frequently vibrates between two positions, two sub-pictures are subjected to staggered overlapping display, and when the plate glass frequently vibrates between four positions, four sub-pictures are subjected to staggered overlapping display, so that the resolution in the visual effect is improved by two times or four times.

For example, when the light beam incident on the galvanometer 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 swings from one position to another position, the shift distances of each pixel of the projection image corresponding to the image light beam are all the same, so that the offsets of the fields of view in the projection lens to the projection screen are the same, and thus, the high-resolution display of the visual picture can be ensured. Wherein the offset of the field of view refers to the actual displacement distance of the field of view.

In the optical engine provided by the embodiment of the application, the light valve of 0.37 inch is provided, the light valve can provide an image picture with a resolution of 1080p, and after the light valve of 0.37 inch is matched with the galvanometer, the image picture with a resolution of 2k or 4k can be further provided, so that the display effect is greatly improved.

To sum up, the optical engine provided in the embodiment of the present application satisfies the corresponding distance parameter ranges through the refractive lens group and the reflective lens group, and satisfies the corresponding proportional size relationship between the focal lengths of the three lens groups in the refractive lens group, so that the lens can achieve a higher imaging requirement with a smaller size, and compared with a refractive lens group formed by a plurality of lenses in the related art, the size of the lens can be smaller. The problem of among the correlation technique the lens quantity of refractor group is more, and then the camera lens volume is difficult to reduce is solved, a less projection lens of volume is provided to and the projection equipment structure of using above-mentioned projection lens also can simplify correspondingly, and the volume does benefit to the compression.

The display resolution of the existing projection equipment is mostly 720P, and a Light Emitting Diode (LED) Light source is mostly adopted to achieve a design scheme of volume miniaturization, but the performance of the LED Light source is difficult to obtain higher brightness; therefore, micro-products having high resolution, high brightness and small size are very visible in the market. The lens is one of the core technologies of projection display, and has certain difficulties in design and processing, and especially, the design of the lens is difficult because the cost and miniaturization are both considered on the premise of ensuring the image quality.

In the embodiment of the application, a light valve based on 0.37 inch liquid crystal on silicon is provided, and an ultra-short-focus projection lens is matched, so that an image picture with a resolution of 1080p can be projected on a screen. In addition, the number of the lenses of the projection lens is less than 14, the number of the aspheric lenses is also less, the complexity and the volume of the projection lens are greatly reduced, and in addition, the aspheric lenses are made of 330R plastic materials, so that the cost is low, and the processing is easy (the aspheric lenses are manufactured in a mould pressing mode), and therefore the volume, the complexity, the cost and the processing of the projection lens are greatly improved. In addition, the projection lens can be applied to a laser light source, so that the brightness of an image picture can be greatly improved.

As shown in fig. 5, an embodiment of the present application further provides a laser projection apparatus, which includes a screen 60 and the optical engine 50 shown in fig. 4. The optical engine 50 may include the lens 20 provided in the embodiment shown in fig. 3.

When the laser projection apparatus is in operation, a light beam emitted from the light source device 54 is emitted to the light valve 51, an emitted light beam from the light valve 51 is emitted to the polarization beam splitter 52, and is emitted to the lens 20 through the polarization beam splitter 52, and is emitted to the screen 60 after being adjusted by the lens 20, so as to form an image frame on the screen 60.

The laser projection equipment that provides in the above-mentioned embodiment adopts telecentric system, the light valve throws with parallel light beam and gets into projection lens, light valve and projection lens still are provided with total reflection prism, or still further be provided with the vibration lens, thereby projection lens is under the prerequisite of reserving sufficient back focal distance, can also realize the optimization of lens quantity through the reasonable collocation of mirror group, set up spherical lens in first mirror group, the combination of two double-cemented lens, the realization is to the correction of elementary aberration, the formation of image burden of rear end lens has been alleviateed, do benefit to the simplification of rear end lens. And the diaphragm is arranged in the first lens group, so that the aperture of the system can be better controlled, and the correction of aberration is facilitated.

In the above embodiments, the first lens group and the second lens group are set as movable groups, and the distance between the reflecting mirror and the third lens group is finely adjusted, so that the projection size can be adjusted under the requirement of ultra-short-focus high-definition projection, and the method is suitable for wider projection requirements.

In this application, the terms "first", "second", "third", "fourth". cndot. twelfth ", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. The term "plurality" means two or more unless expressly limited otherwise.

The above description is only exemplary of the present application and should not be taken as limiting, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A projection lens is characterized by comprising a refraction lens group and a reflection lens group which are arranged along the light emergent direction of a light valve;

the refracting mirror group includes follows first mirror group, second mirror group and third mirror group that the light-emitting direction set gradually, first mirror group the second mirror group with the third mirror group satisfies 2 < | F₂/F₁|＜12，2＜|F₃/F₁<15 and 1 < | F₄/F₁If | < 10, the F1 is an equivalent focal length of the projection lens, the F2 is an equivalent focal length of the first lens group, the F3 is an equivalent focal length of the second lens group, and the F4 is an equivalent focal length of the third lens group;

2. The projection lens of claim 1 wherein the set of refractors and reflector meet 1.05 < L₁/L₂＜1.5，0.05＜B/(L₁+L₂) < 0.25, said L₁Is the length of said refractive lens group, said L₂The distance between the refractor set and the reflector set is defined, and the distance between the refractor set and the light valve is defined as B.

3. The projection lens of claim 2 further comprising an aperture stop between the sixth lens and the seventh lens of the first lens group.

4. The projection lens of claim 2, wherein 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, negative, positive and negative in sequence.

5. A projection lens according to any one of claims 2 to 4, wherein the refractive and reflective mirror groups further satisfy 0.1<B/L₂<0.35。

6. The projection lens of claim 5 wherein the set of mirrors comprises a curved mirror satisfying a ratio of 32 mm ≦ (| R |) IC)/17.65 ≦ 47mm, -5 ≦ C ≦ 0, R being a center radius of curvature of the curved mirror, IC being an image circle size of the projection lens, and C being a conic coefficient of the curved mirror.

7. The projection lens of claim 6 wherein the curved mirror is an aspheric concave mirror.

8. The projection lens as claimed in any of claims 2 to 4, wherein the second lens group comprises a ninth lens, the third lens group comprises 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 aspheric lens.

9. The projection lens of claim 8 wherein the focal power of the second lens group is positive, the focal powers of the tenth, eleventh and twelfth lenses are sequentially positive, negative and negative, and the focal power of the refractive lens group and the focal power of the reflective lens group are both positive.

10. A projection device comprising the projection lens according to any one of claims 1 to 9.