Projection lens and projection system

Abstract

The invention discloses a projection lens and a projection system. The projection lens comprises a first lens group, a diaphragm and a second lens group which are coaxially arranged, wherein the first lens group and the second lens group are respectively located at two sides of the diaphragm. The first lens group comprises at least one lens, and the second lens group comprises at least one lens; the projection lens satisfies the following conditions: 0.2 < = f / TTL * F.NO < = 1.2; the projection lens provided by the embodiment of the invention only comprises the two lens groups, and the focal length, the length and the F number of the projection lens are limited in the range, so that the size of the projection lens can be effectively reduced while the large-aperture characteristic of an optical system is ensured, and the ultrathin characteristic and the miniaturization of the projection lens are realized.

Description

Technical Field

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

[0002] Projection display technology is a technology that uses optical systems and projection space to magnify and display image information. The projection system is an optical imaging system that ultimately displays images. The projection lens greatly affects the application scenarios and imaging quality of the projection system. The size of the projection lens also affects the volume of the optical engine.

[0003] With the rapid development of projection technology, its application demand patterns are becoming more and more diversified. In order to meet the needs of different application scenarios, in some cases it is necessary to reduce the size of the projection lens, thereby reducing the overall volume of the optical engine. Summary of the invention

[0004] According to a first aspect of an embodiment of the present invention, there is provided a projection lens, comprising: an aperture, and a first lens group and a second lens group respectively located on both sides of the aperture; the first lens group, the aperture and the second lens group are coaxially arranged; the first lens group includes at least one lens, and the second lens group includes at least one lens;

[0005] The projection lens meets the following requirements:

[0006] 0.2≤f / TTL×F.NO≤1.2;

[0007] Wherein, f represents the focal length of the projection lens, TTL represents the length of the projection lens along the optical axis, and F.NO represents the aperture value of the projection lens.

[0008] In some embodiments of the present invention, the first lens group includes: a first lens and a second lens; the second lens is located between the first lens and the aperture;

[0009] The first lens is a negative lens, and the second lens is a positive lens.

[0010] In some embodiments of the present invention, the first lens is an aspherical lens, and the second lens is a spherical lens.

[0011] In some embodiments of the present invention, the first lens satisfies:

[0012] 0≤ct12 / et12≤2;

[0013] Wherein, ct12 represents the center thickness of the first lens along the optical axis, and et12 represents the edge thickness of the first lens along the optical axis;

[0014] The second lens satisfies:

[0015] 1≤ct34 / et34≤3;

[0016] f34≥4;

[0017] Wherein, ct34 represents the center thickness of the second lens along the optical axis, et34 represents the edge thickness of the second lens along the optical axis, and f34 represents the focal length of the second lens.

[0018] In some embodiments of the present invention, the second lens group includes: a third lens, a fourth lens, a fifth lens and a sixth lens; the third lens is located on a side of the aperture away from the first lens group, the fourth lens is located between the third lens and the fifth lens, and the sixth lens is located on a side of the fifth lens away from the fourth lens;

[0019] The third lens is a negative lens, the fourth lens is a positive lens, the fifth lens is a positive lens, and the sixth lens is a positive lens.

[0020] In some embodiments of the present invention, the fifth lens is an aspherical lens, and the third lens, the fourth lens and the sixth lens are all spherical lenses.

[0021] In some embodiments of the present invention, the sixth lens is a field lens, and the distance between the fifth lens and the sixth lens exceeds 4 mm.

[0022] In some embodiments of the present invention, the third lens satisfies:

[0023] 0≤ct67 / et67≤2;

[0024] f67≥-6;

[0025] Wherein, ct67 represents the center thickness of the third lens along the optical axis, et67 represents the edge thickness of the third lens along the optical axis, and f67 represents the focal length of the third lens;

[0026] The fourth lens satisfies:

[0027] 1≤ct89 / et89≤4;

[0028] f89≥6;

[0029] Wherein, ct89 represents the center thickness of the fourth lens along the optical axis, et89 represents the edge thickness of the fourth lens along the optical axis, and f89 represents the focal length of the fourth lens;

[0030] The fifth lens satisfies:

[0031] 0.5≤ct1011 / et1011≤3;

[0032] f1011≥9;

[0033] Wherein, ct1011 represents the center thickness of the fifth lens along the optical axis, et1011 represents the edge thickness of the fifth lens along the optical axis, and f1011 represents the focal length of the fifth lens;

[0034] The sixth lens satisfies:

[0035] 0.5≤ct2122 / et2122≤3;

[0036] f2122≥16;

[0037] Among them, ct2122 represents the center thickness of the sixth lens along the optical axis, et2122 represents the edge thickness of the sixth lens along the optical axis, and f2122 represents the focal length of the sixth lens.

[0038] In some embodiments of the present invention, the thickness of the projection lens satisfies:

[0039] 0.3≤(CT1+CT6) / ∑CT≤0.6;

[0040] Wherein, CT1 represents the center thickness of the first lens along the optical axis, CT6 represents the center thickness of the sixth lens along the optical axis, and ΣCT represents the sum of the center thicknesses of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens along the optical axis.

[0041] According to a second aspect of an embodiment of the present invention, a projection system is provided, comprising:

[0042] Projection light source;

[0043] An illumination system, located at the light-emitting side of the projection light source; the illumination system comprises a light modulator;

[0044] A projection lens, wherein the projection lens is any of the above-mentioned projection lenses; the projection lens is located at the light-emitting side of the light modulator.

[0045] A projection lens and a projection system, comprising a first lens group, an aperture, and a second lens group arranged coaxially; wherein the first lens group and the second lens group are respectively located on both sides of the aperture. The first lens group includes at least one lens, and the second lens group includes at least one lens; and the projection lens satisfies: 0.2≤f / TTL×F.NO≤1.2; the projection lens provided by the embodiment of the present invention only includes two lens groups, and by limiting the focal length, length, and F number of the projection lens within the above range, it is possible to ensure that the optical system has a large aperture characteristic while effectively reducing the size of the projection lens, thereby achieving ultra-thin characteristics and miniaturization of the projection lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings introduced below are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative work.

[0047] Figure 1 A schematic diagram of the structure of a projection system provided by an embodiment of the present invention;

[0048] Figure 2 A schematic diagram of the imaging principle of a projection device provided by an embodiment of the present invention;

[0049] Figure 3 A schematic diagram of the structure of a projection lens provided in an embodiment of the present invention;

[0050] Figure 4 An optical path diagram of a projection lens provided by an embodiment of the present invention;

[0051] Figure 5 One of the zoom schematic diagrams of the projection lens provided by the embodiment of the present invention;

[0052] Figure 6 A second zoom schematic diagram of a projection lens provided by an embodiment of the present invention;

[0053] Figure 7 A modulation transfer function curve diagram provided by an embodiment of the present invention;

[0054] Figure 8 A defocus curve diagram provided by an embodiment of the present invention;

[0055] Fig. 9 A spot diagram provided for an embodiment of the present invention;

[0056] Fig.10 A schematic diagram of a field curvature curve provided by an embodiment of the present invention;

[0057] Fig.11A schematic diagram of a distortion curve provided by an embodiment of the present invention;

[0058] Fig.12 A telecentricity curve diagram provided by an embodiment of the present invention;

[0059] Fig.13 A vertical axis chromatic aberration curve diagram provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0060] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and understandable, the present invention will be further described below with reference to the accompanying drawings and examples. However, the exemplary embodiments can be implemented in various forms and should not be understood as being limited to the embodiments described herein; on the contrary, these embodiments are provided to make the present invention more comprehensive and complete, and to fully convey the concepts of the exemplary embodiments to those skilled in the art. The same figure marks in the figures represent the same or similar structures, and thus their repeated descriptions will be omitted. The words expressing position and direction described in the present invention are all explained with reference to the accompanying drawings as examples, but changes can be made as needed, and the changes made are all included in the scope of protection of the present invention. The drawings of the present invention are only used to illustrate the relative position relationship and do not represent the true proportion.

[0061] Projection display technology is a technology that uses optical systems and projection space to magnify and display image information. The projection system is an optical imaging system that ultimately displays the image. With the continuous development of projection technology, laser projection systems have been widely used in large-screen displays, laser TVs, digital cinemas, portable projection displays, and other fields due to their unique advantages. Laser projection display can display more realistic and gorgeous dynamic images on ultra-large screens, achieving visual shock effects that other display technologies cannot achieve.

[0062] Figure 1 A schematic diagram of the structure of a projection system provided by an embodiment of the present invention.

[0063] like Figure 1 As shown, in actual application, the front projection system may include: a projection device 100 and a projection screen 200 .

[0064] The projection screen 200 is located on the light emitting side of the projection device 100. The audience faces the projection screen 200. The projection device 100 emits projection light, which is incident on the projection screen 200 and reflected toward the audience's position through the projection screen 200, so that the audience can view the projected image.

[0065] The projection device is provided with a projection lens, and the specifications of the projection lens will affect the size of the projection image and the projection distance. In actual applications, ultra-short-throw, short-throw or long-throw projection lenses are used according to different application scenarios.

[0066] Figure 2 A schematic diagram of the imaging principle of a projection device provided in an embodiment of the present invention.

[0067] like Figure 2 As shown, the projection device includes: a projection light source 1, an illumination system 2 and a projection lens 3. The illumination system 2 is located at the light-emitting side of the projection light source 1, and a light modulator 21 is provided in the illumination system 2. The light modulator 21 is used to modulate the incident light before emitting it, and the projection lens 3 is located at the light-emitting side of the light modulator 21.

[0068] The projection light source 1 can be a light emitting diode (LED) light source or a laser light source. LED light sources have the advantages of low power consumption, small size, and long life, and are suitable for application scenarios such as small-size projection. Laser light sources have higher brightness and better color saturation, and can optimize the display effect of the projected image.

[0069] In an embodiment of the present invention, a laser light source may be used as a projection light source. The laser light source may be a monochromatic laser or a laser that can emit lasers of multiple colors or multiple lasers that emit lasers of different colors. When a monochromatic laser is used as the laser light source, the laser display device also needs to be provided with a color wheel, which is used for color conversion. The monochromatic laser cooperates with the color wheel to achieve the purpose of emitting primary color lights of different colors in a time sequence. When a laser light source is used that can emit lasers of multiple colors, it is necessary to control the laser light source to emit lasers of different colors as primary color lights in a time sequence. The use of a three-color laser light source is conducive to improving the color gamut of the projected image, has better color expression, and can accurately reproduce the input image.

[0070] The illumination system 2 is located at the light-emitting side of the projection light source 1. On the one hand, the illumination system 2 collimates and homogenizes the emitted light of the projection light source 1, and on the other hand, it enables the emitted light of the projection light source 1 to be incident on the light modulator 21 at a suitable angle. The illumination system 2 may include a plurality of lenses or lens groups, light guides, diffusers, diffuser wheels and other components, which are not limited here.

[0071] The light modulator 21 is used to modulate the incident light to form an image. In a specific implementation, the light modulator 21 can be a transmission light modulator or a reflection light modulator. Figure 2 The light modulator 21 shown is a reflective light modulator. The light modulator 21 receives the light reflected by the beam splitter prism P, modulates the incident light, and reflects the modulated light. Since the light path is folded back through the reflective light modulator, the volume of the projection device can be reduced.

[0072] In the embodiment of the present invention, the light modulator 21 may be Liquid Crystal on Silicon (LCoS) or a Digital Micromirror Device (DMD).

[0073] LCoS is based on semiconductor technology, which combines a complementary metal oxide semiconductor (CMOS) substrate with a glass substrate containing transparent electrodes, and then injects liquid crystal packaging. LCoS has the characteristics of high aperture ratio and high resolution of each pixel, and can form high-resolution images.

[0074] The DMD includes a large number of tiny reflectors, each of which can be driven individually to deflect. By controlling the deflection angle of the DMD, the brightness of the light incident on the projection lens 3 is controlled.

[0075] The beam splitter P is used to separate the illumination beam and the imaging beam. The beam emitted by the projection light source is shaped and homogenized and finally reflected toward the light modulator 21 by the beam splitter P. The light emitted after being modulated by the light modulator 21 passes through the beam splitter P and enters the projection lens 3 and is emitted.

[0076] In a specific implementation, an image shift component (not shown) may be further provided on the light output side of the light modulator 21. The image polarization component may generally be made of flat glass. Image shift may be achieved through high-frequency vibration, thereby realizing high-resolution image display.

[0077] After the light modulator 21 modulates the incident light to form an image, the light is reflected toward the projection lens 3, which forms an image, thereby projecting the image to a suitable size for viewing.

[0078] The size of the projection lens will affect the overall volume of the projection device. Therefore, with the trend of miniaturization of projection equipment, it is necessary to design a small projection lens with a smaller size while ensuring the imaging quality.

[0079] Figure 3 A schematic diagram of the structure of a projection lens provided in an embodiment of the present invention; Figure 4 This is a light path diagram of a projection lens provided in an embodiment of the present invention.

[0080] like Figure 3 As shown, the projection lens includes a first lens group 31, an aperture s, and a second lens group 32 arranged coaxially; wherein the first lens group 31 and the second lens group 32 are respectively located on both sides of the aperture s. The first lens group 31 includes at least one lens, and the second lens group 32 includes at least one lens; and the projection lens satisfies:

[0081] 0.2≤f / TTL×F.NO≤1.2;

[0082] Wherein, f represents the focal length of the projection lens, TTL represents the length of the projection lens along the optical axis, and F.NO represents the aperture value of the projection lens.

[0083] The projection lens provided in the embodiment of the present invention includes only two lens groups. By limiting the focal length, length and F number of the projection lens within the above ranges, it is possible to ensure that the optical system has a large aperture characteristic while effectively reducing the size of the projection lens, thereby achieving ultra-thin characteristics and miniaturization of the projection lens.

[0084] Specifically, Figure 3 As shown, the first lens group 31 includes: a first lens l1 and a second lens l2; the second lens l2 is located between the first lens l1 and the aperture s. The first lens l1 is a negative lens, and the second lens l2 is a positive lens.

[0085] The second lens group 32 includes: a third lens 13, a fourth lens 14, a fifth lens 15 and a sixth lens 16; the third lens 13 is located on the side of the aperture s away from the first lens group 31, the fourth lens 14 is located between the third lens 13 and the fifth lens 15, and the sixth lens 16 is located on the side 14 of the fifth lens 15 away from the fourth lens. Among them, the third lens 13 is a negative lens, the fourth lens 14 is a positive lens, the fifth lens 15 is a positive lens, and the sixth lens 16 is a positive lens.

[0086] When designing a projection lens, the display surface of the light modulator 21 is used as the image surface, and the image of a specific position with a set size is used as the object surface. The parameters of the projection lens are optimized by utilizing the reversible nature of the optical path. Figure 4 As shown, the light emitted from the light modulator 21 first passes through the dichroic prism P to reach the projection lens, is incident from one side of the second lens group 32 of the projection lens, passes through the aperture s and the first lens group 31, and is imaged at the above-mentioned specific position to obtain an image of a set size.

[0087] In the embodiment of the present invention, Figure 2 and Figure 3 As shown, the sixth lens 16 is a field lens. The last lens before the light emitted by the illumination system 2 is incident on the light modulator 21 shares the first lens before the light modulated by the light modulator 21 is incident on the projection lens 3. The shared lens is the sixth lens 16. The sixth lens 16 uses a field lens to replace the role of the beam splitter prism, reducing the number of components used in the optical engine, and thus can reduce the size of the optical engine.

[0088] Since the sixth lens 16 in the projection lens is a field lens, light emitted from the projection light source 1 needs to be incident from the field lens first, and then modulated by the light modulator 21 before being emitted from the field lens. In order to avoid interference between the lens in the projection lens 3 and the projection light source 1 and the components in the illumination system 2, the distance between the fifth lens 15 and the sixth lens 16 is relatively large when designing the projection lens. In the embodiment of the present invention, the distance between the fifth lens 15 and the sixth lens 16 exceeds 4 mm.

[0089] The projection screen provided by the embodiment of the present invention can also realize zoom imaging at different object distances. Figure 5 and Figure 6 , Figure 5 This is one of the zoom diagrams of the projection lens provided by an embodiment of the present invention, Figure 6 The second zoom schematic diagram of the projection lens provided by the embodiment of the present invention.

[0090] like Figure 5 and Figure 6 As shown, when zoom imaging is performed, the distance between the fifth lens and the sixth lens in the projection lens can be changed, so that clear images of different focal lengths are displayed on the projection screen. Specifically, when the lens spacing is changed, the sixth lens l6 (field lens) and the light modulator 21 remain in the same position, that is, the sixth lens l6 is fixed, and the first lens l1 to the fifth lens l5 are moved at the same time to change the distance between the fifth lens l5 and the sixth lens l6.

[0091] In the embodiment of the present invention, the first lens 11 and the fifth lens 15 are aspherical lenses, and the second lens 12, the third lens 13, the fourth lens 14 and the sixth lens 16 are all spherical lenses. The projection lens includes only six lenses, and only two aspherical lenses are needed to have a better imaging quality. The optical system structure is simple and compact. The total length from the first lens 11 to the fifth lens 15 can be reduced to less than 19.62 mm, and the total length from the first lens 11 to the sixth lens 16 can be reduced to less than 21.72 mm.

[0092] Among them, the first lens l1 satisfies:

[0093] 0≤ct12 / et12≤2;

[0094] Wherein, ct12 represents the center thickness of the first lens l1 along the optical axis, and et12 represents the edge thickness of the first lens l1 along the optical axis.

[0095] By controlling the parameters of the first lens l1 to satisfy the above range, the aberration and field curvature of the projection lens can be balanced.

[0096] The second lens l2 satisfies:

[0097] 1≤ct34 / et34≤3;

[0098] f34≥4;

[0099] Wherein, ct34 represents the center thickness of the second lens L2 along the optical axis, et34 represents the edge thickness of the second lens L2 along the optical axis, and f34 represents the focal length of the second lens L2.

[0100] The third lens l3 satisfies:

[0101] 0≤ct67 / et67≤2;

[0102] f67≥-6;

[0103] Among them, ct67 represents the center thickness of the third lens L3 along the optical axis, et67 represents the edge thickness of the third lens L3 along the optical axis, and f67 represents the focal length of the third lens L3.

[0104] The fourth lens l4 satisfies:

[0105] 1≤ct89 / et89≤4;

[0106] f89≥6;

[0107] Wherein, ct89 represents the center thickness of the fourth lens L4 along the optical axis, et89 represents the edge thickness of the fourth lens L4 along the optical axis, and f89 represents the focal length of the fourth lens L4;

[0108] The fifth lens l5 satisfies:

[0109] 0.5≤ct1011 / et1011≤3;

[0110] f1011≥9.

[0111] Wherein, ct1011 represents the center thickness of the fifth lens l5 along the optical axis, et1011 represents the edge thickness of the fifth lens l5 along the optical axis, and f1011 represents the focal length of the fifth lens l5;

[0112] The sixth lens l6 satisfies:

[0113] 0.5≤ct2122 / et2122≤3;

[0114] f2122≥16;

[0115] Wherein, ct2122 represents the center thickness of the sixth lens l6 along the optical axis, et2122 represents the edge thickness of the sixth lens l6 along the optical axis, and f2122 represents the focal length of the sixth lens l6.

[0116] By controlling the parameters of the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5 and the sixth lens L6 to meet the above ranges, the processability of the lens can be guaranteed, the aberration of the projection lens can be effectively balanced, and the aberration control of the lens can be facilitated.

[0117] The thickness of the projection lens meets the following requirements:

[0118] 0.3≤(CT1+CT6) / ∑CT≤0.6;

[0119] Wherein, CT1 represents the center thickness of the first lens l1 along the optical axis, CT6 represents the center thickness of the sixth lens l6 along the optical axis, and ∑CT represents the sum of the center thicknesses of the first lens l1, the second lens l2, the third lens l3, the fourth lens l4, the fifth lens l5 and the sixth lens l6 along the optical axis.

[0120] By properly controlling the proportion of the center thickness of the first lens l1 and the sixth lens l6 in the center thickness of the entire lens, it is beneficial to properly distribute the system optical power, improve the system spherical aberration and aberration, and enhance the stability of the system structure.

[0121] The embodiment of the present invention designs the surface shape and combination of the six lenses in the projection lens, so that the projection ratio of the projection lens can be 1.2. The projection ratio is the ratio of the width of the projection screen of the projection lens to the distance of the projection screen from the projection lens. The projection ratio value satisfied by the projection lens provided by the embodiment of the present invention is a projection ratio value that is more comfortable for users to use. The total length of the projection lens represents the distance from the first lens to the sixth lens on the optical axis. The distance is less than 21.72mm, which makes the projection lens have a shorter length, which is beneficial to reducing the volume of the projection equipment. The F.NO of the projection lens characterizes the light collecting ability of the lens. The larger the value, the smaller the light collecting angle; the smaller the value, the larger the light collecting angle. The F.NO of the projection lens provided by the embodiment of the present invention is 2.4, which has a strong light collecting ability and a large luminous flux.

[0122] The surface parameters of each optical component in the projection lens provided by the embodiment of the present invention and the spacing between the optical components are shown in the following table:

[0123] Face number Face type Radius of curvature thickness Material Semi-aperture OBJ Spherical unlimited 500 250.982 S1 Aspheric 3.991 1.415 1.74；49.3 refraction 2.72 S2 Aspheric 1.852 2.175 refraction 1.936 S3 Spherical 14.411 1 1.81；22.7 refraction 1.75 S4 Spherical -7.029 0.321 refraction 1.656 Aperture Spherical unlimited 1.414 refraction 1.375 S6 Spherical -5.497 1 1.96；17.5 refraction 1.713 S7 Spherical -7.474E+05 0.438 refraction 2.111 S8 Spherical -25.189 1.416 1.5；81.6 refraction 2.344 S9 Spherical -3.724 0.201 refraction 2.573 S10 Aspheric 10.471 3.104 1.62；63.9 refraction 3.053 S11 Aspheric -18.029 4.132 refraction 2.985 S21 Spherical 14.2 3 1.81；40.9 refraction 3.175 S22 Spherical unlimited 0.5 refraction 2.963 S23 Spherical unlimited 1.1 1.51；62.9 refraction 2.889 S24 Spherical unlimited 0.5 refraction 2.783 S25 Spherical unlimited 0 2.711

[0124] Aspheric coefficients are shown in the following table:

[0125] surface S1 S2 S10 S11 Conic surface constant -5.348 -0.575 -0.621 -1.554 4th order coefficient 7.062E-03 -4.164E-03 1.116E-03 1.935E-03 6th order coefficient -1.189E-03 -2.075E-03 2.116E-05 1.072E-05 8th order coefficient -1.104E-04 3.925E-04 9.554E-07 6.754E-06 10th order coefficient -5.153E-06 -6.905E-05 -5.37E-08 -1.779E-07

[0126] Based on the above parameters, the projection lens is a telephoto lens with a projection ratio of 1.2, an effective focal length of 5.4mm, a resolution of up to 66lp / mm, and an image distance of 500mm to 1200mm.

[0127] The embodiment of the present invention also evaluates the image quality of the projection lens based on the above parameter optimization results.

[0128] Figure 7 This is a modulation transfer function curve diagram provided by an embodiment of the present invention.

[0129] Figure 7 The Modulation Transfer Function (MTF) curves of light with wavelengths of 0.4650 μm to 0.6430 μm in different fields of view are shown, where the horizontal axis represents the spatial frequency in cycles / mm, and the vertical axis represents the OTF modulus. The MTF value can characterize the resolution of the projection lens. Figure 7 It can be seen that the MTF values ​​of the light are all above 0.6 and the curve is relatively flat, indicating that the imaging difference between the edge and center of the projection lens is small and the imaging quality meets the design standard.

[0130] Figure 8 This is a defocus curve diagram provided by an embodiment of the present invention.

[0131] Figure 8 The figure shows the defocus curves of light with a wavelength of 0.4650 μm to 0.6430 μm in different fields of view when the spatial frequency is 66.0000 cycles / mm, where the horizontal axis represents the focal shift (defocus position) in mm and the vertical axis represents the OTF modulus. Figure 8 It can be seen that the MTF values ​​of the light at the optical axis are all above 0.6, and the image plane shift degree is within a reasonable range.

[0132] Fig. 9 A point diagram provided for an embodiment of the present invention.

[0133] The spot diagram can reflect the clarity of the projection lens image. The more concentrated the points in the diagram, the less smear and the better the sharpness of the projection lens image. Fig. 9 The image spot diagram (Spot Size diagram) of light with wavelengths of 0.465μm, 0.525μm and 0.643μm in six fields of view is shown. Fig. 9 It can be seen that the images formed by the projection lens in different fields of view can be within a reasonable range. The root mean square (RNS) radius and geometric (GEO) radius data corresponding to the images formed in the six fields of view simulated by the embodiment of the present invention are shown in the following table:

[0134] Field of view 1 2 3 4 5 6 RNS radius (μm) 1.567 1.930 1.940 2.131 2.597 3.734 GEO radius (μm) 2.762 4.480 4.929 4.642 2.963 10.872

[0135] Fig.10 A schematic diagram of a field curvature curve provided by an embodiment of the present invention.

[0136] Fig.10The field curvature curves of the image formed by the light with wavelengths of 0.643μm, 0.525μm and 0.465μm in the meridian direction and sagittal direction under different fields of view are shown, where the abscissa represents the field curvature size in mm, and the ordinate represents the image height (field of view). Fig.10 It can be seen that the field curvature of the projection lens is within the range of ±0.1 mm, and the field curvature of the projection lens is within a reasonable range.

[0137] Fig.11 A schematic diagram of a distortion curve provided by an embodiment of the present invention.

[0138] Fig.11 The distortion curves of the images formed by light with wavelengths of 0.643μm, 0.525μm and 0.465μm within a certain field of view are shown, where the horizontal axis represents the distortion percentage and the vertical axis represents the image height (field of view). Distortion represents the degree of distortion of the image formed by the optical system on the object relative to the object itself. The thickness of the lens and its position relative to the aperture stop determine its contribution to the system distortion. Fig.11 It can be seen that the maximum distortion of the projection lens is about 0.12%, and the distortion of the projection lens is within a reasonable range.

[0139] Fig.12 A telecentricity curve diagram provided by an embodiment of the present invention.

[0140] Fig.12 The bar graph shows the telecentricity of the outgoing light of the projection lens under different fields of view, where the horizontal axis represents the field of view size, and the vertical axis represents the angular telecentricity of the main light relative to the optical axis. The specific data are shown in the following table:

[0141]

[0142] Depend on Fig.12 It can be seen that the telecentricity of the projection lens is less than 0.03°, and the performance of the projection lens is good.

[0143] Fig.13 The vertical chromatic aberration of light with wavelengths of 0.643 μm, 0.525 μm and 0.465 μm when imaged within a certain field of view is shown in the figure, where the horizontal axis reflects the magnitude of the vertical chromatic aberration in μm, and the vertical axis is the field of view angle. The two vertical lines in the figure are the range of the Airy disk. Fig.13 It can be seen that within the Airy disk range, the vertical axis chromatic aberration of the green light g and the red light r relative to the blue light b is within a reasonable range.

[0144] comprehensive Figure 7 to Figure 13 It can be seen from the image quality evaluation results that the projection lens provided by the embodiment of the present invention has small aberration and chromatic aberration during imaging and has good imaging quality.

[0145] Based on the same inventive concept, an embodiment of the present invention further provides a projection system, such as Figure 1 As shown, the projection system may include a projection device 100 and a projection screen 200, and the projection device may include any of the above-mentioned projection lenses. Since the total length of the projection lens provided by the embodiment of the present invention is only less than 21.72 mm, the volume of the projection device can be effectively reduced, and a miniaturized design of the projection device can be achieved.

[0146] According to the first inventive concept, the projection lens includes a second lens group, an aperture, and a first lens group coaxially arranged in sequence along the propagation direction of light. The projection lens satisfies: 0.2≤f / TTL×F.NO≤1.2. Only two lens groups are required. By limiting the focal length, length, and F number of the projection lens within the above range, it is possible to ensure that the optical system has a large aperture characteristic while effectively reducing the size of the projection lens, thereby achieving ultra-thin characteristics and miniaturization of the projection lens.

[0147] According to the second invention concept, the first lens group includes: a first lens and a second lens, the first lens is a negative lens, and the second lens is a positive lens. The second lens group includes a third lens, a fourth lens, a fifth lens, and a sixth lens arranged in sequence along a direction gradually away from the first lens group; wherein the third lens is a negative lens, the fourth lens is a positive lens, the fifth lens is a positive lens, and the sixth lens is a positive lens. The aperture is located between the second lens and the third lens. By moving the first lens to the fifth lens as a whole along the optical axis direction, the distance between the fifth lens and the sixth lens changes, thereby realizing zoom imaging at different object distances.

[0148] According to the third invention concept, the first lens and the fifth lens are aspherical lenses, and the second lens, the third fourth lens and the sixth lens are spherical lenses. The projection lens includes only six lenses, and only two aspherical lenses are needed to have better imaging quality. The optical system structure is simple and compact, and the total length of the lens can be reduced to less than 21.72 mm.

[0149] According to the fourth invention, the thickness of the first lens satisfies: 0≤ct12 / et12≤2; by controlling the parameters of the first lens to satisfy the above range, the aberration and field curvature of the projection lens can be balanced.

[0150] According to the fifth inventive concept, the second lens satisfies: 1≤ct34 / et34≤3; f34≥4; and the processability of the lens can be ensured by controlling the parameters of the second lens to satisfy the above ranges.

[0151] According to the sixth invention concept, the third lens satisfies: 0≤ct67 / et67≤2; f67≥-6; and the processability of the lens can be ensured by controlling the parameters of the third lens to satisfy the above ranges.

[0152] According to the seventh invention, the fourth lens satisfies: 1≤ct89 / et89≤4; f89≥6; and the processability of the lens can be ensured by controlling the parameters of the fourth lens to meet the above ranges.

[0153] According to the eighth invention, the fifth lens satisfies: 0.5≤ct1011 / et1011≤3; f1011≥9; and the processability of the lens can be ensured by controlling the parameters of the fifth lens to meet the above ranges.

[0154] According to the ninth invention, the sixth lens satisfies: 0.5≤ct2122 / et2122≤3; f2122≥16; and the processability of the lens can be ensured by controlling the parameters of the sixth lens to meet the above ranges.

[0155] According to the tenth inventive concept, by controlling the parameters of the first lens to the sixth lens to satisfy the above ranges, the processability of the lens can be ensured, the aberration of the projection lens can be effectively balanced, and the aberration control of the lens can be facilitated.

[0156] According to the eleventh invention concept, the thickness of the projection lens satisfies: 0.3≤(CT1+CT6) / ∑CT≤0.6; by reasonably controlling the proportion of the center thickness of the first lens and the sixth lens in the overall center thickness of the lens, it is beneficial to reasonably distribute the system optical power, improve the system spherical aberration and aberration, and enhance the stability of the system structure.

[0157] According to the twelfth invention, the projection ratio of the projection lens is 1.2, the total length is less than 21.72 mm, the F.NO is 2.4, and the resolution can reach 66 lp / mm.

[0158] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0159] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A projection lens, characterized in that: include: An aperture, and a first lens group and a second lens group respectively located on both sides of the aperture; The first lens group, the aperture and the second lens group are coaxially arranged; the first lens group includes at least one lens, and the second lens group includes at least one lens; The projection lens meets the following requirements: 0.2≤f / TTL×F.NO≤1.2; Wherein, f represents the focal length of the projection lens, TTL represents the length of the projection lens along the optical axis, and F.NO represents the aperture value of the projection lens.

2. The projection lens according to claim 1, wherein: The first lens group includes: a first lens and a second lens; the second lens is located between the first lens and the aperture; The first lens is a negative lens, and the second lens is a positive lens.

3. The projection lens according to claim 2, wherein: The first lens is an aspherical lens, and the second lens is a spherical lens.

4. The projection lens according to claim 2, wherein: The first lens satisfies: 0≤ct12 / et12≤2; Wherein, ct12 represents the center thickness of the first lens along the optical axis, and et12 represents the edge thickness of the first lens along the optical axis; The second lens satisfies: 1≤ct34 / et34≤3; f34≥4； Wherein, ct34 represents the center thickness of the second lens along the optical axis, et34 represents the edge thickness of the second lens along the optical axis, and f34 represents the focal length of the second lens.

5. The projection lens according to claim 2, wherein: The second lens group includes: a third lens, a fourth lens, a fifth lens and a sixth lens; the third lens is located on a side of the aperture away from the first lens group, the fourth lens is located between the third lens and the fifth lens, and the sixth lens is located on a side of the fifth lens away from the fourth lens; The third lens is a negative lens, the fourth lens is a positive lens, the fifth lens is a positive lens, and the sixth lens is a positive lens.

6. The projection lens according to claim 5, wherein: The fifth lens is an aspherical lens, and the third lens, the fourth lens and the sixth lens are all spherical lenses.

7. The projection lens according to claim 5, wherein: The sixth lens is a field lens, and the distance between the fifth lens and the sixth lens exceeds 4 mm.

8. The projection lens according to claim 5, wherein: The third lens satisfies: 0≤ct67 / et67≤2; f67≥-6； Wherein, ct67 represents the center thickness of the third lens along the optical axis, et67 represents the edge thickness of the third lens along the optical axis, and f67 represents the focal length of the third lens; The fourth lens satisfies: 1≤ct89 / et89≤4; f89≥6； Wherein, ct89 represents the center thickness of the fourth lens along the optical axis, et89 represents the edge thickness of the fourth lens along the optical axis, and f89 represents the focal length of the fourth lens; The fifth lens satisfies: 0.5≤ct1011 / et1011≤3; f1011≥9； Wherein, ct1011 represents the center thickness of the fifth lens along the optical axis, et1011 represents the edge thickness of the fifth lens along the optical axis, and f1011 represents the focal length of the fifth lens; The sixth lens satisfies: 0.5≤ct2122 / et2122≤3; f2122≥16； Among them, ct2122 represents the center thickness of the sixth lens along the optical axis, et2122 represents the edge thickness of the sixth lens along the optical axis, and f2122 represents the focal length of the sixth lens.

9. The projection lens according to claim 5, wherein: The thickness of the projection lens satisfies: 0.3≤(CT1+CT6) / ∑CT≤0.6; Wherein, CT1 represents the center thickness of the first lens along the optical axis, CT6 represents the center thickness of the sixth lens along the optical axis, and ΣCT represents the sum of the center thicknesses of the first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens along the optical axis.

10. A projection system, characterized in that: include: Projection light source; An illumination system, located at the light-emitting side of the projection light source; the illumination system comprises a light modulator; A projection lens, wherein the projection lens is the projection lens according to any one of claims 1 to 9; the projection lens is located on the light output side of the light modulator.

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