Projection lens and projection system

Abstract

The projection lens comprises a refraction system and a reflection system, and the refraction system comprises a rear lens group, a middle lens group and a front lens group. By reasonably optimizing parameters such as the number, the size and the surface type of the lenses in the projection lens, the projection ratio of the projection lens can be reduced to 0.19-0.22, so that the projection distance is further reduced when pictures with the same size are projected. When the size of a picture is adjusted, clear imaging under various sizes of 88 inches to 120 inches can be realized by adjusting the position of the middle lens group and the distance between the projection lens and the projection screen. The projection lens comprises two doublet lens groups, one triplet lens group and three aspheric lenses, the structure is simple, chromatic aberration of three-color laser can be specially optimized, and the chromatic aberration range is controlled to be 0.3 pixel.

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 is a technology that uses a flat image information to control the light source, and uses an optical system and projection space to magnify the image and display it on the projection screen. With the development of projection display technology, the application fields of projection display products are becoming more and more extensive. Projection display has the advantages of screen size and clear display, which is suitable for large-screen display requirements.

[0003] As the core component of projection display, the projection lens has certain difficulties from design to processing. In order to avoid the problem that the distance between the projection device and the projection screen is far, which requires a large projection space, and the movement of objects between the projection device and the projection screen affects the display effect, ultra-short-throw projection equipment came into being. However, the projection ratios of current ultra-short-throw projection equipment are mostly concentrated in 0.22-0.25, which still leads to a long distance between the projection device and the projection screen, and the display size is single, which cannot meet the demand for the display screen to become larger; when the image is displayed with a laser light source, there is also the problem of color smear at the edge of the display screen. Summary of the invention

[0004] An embodiment of the present invention provides a projection lens, comprising: a refraction system and a reflection system arranged in sequence along a propagation direction of light;

[0005] Wherein, the refraction system comprises: a rear lens group, a middle lens group and a front lens group arranged in sequence along the propagation direction of light; the rear lens group comprises two doublet lens groups and one triplet lens group;

[0006] The reflection system includes a reflector;

[0007] The projection ratio of the projection lens is 0.19-0.22.

[0008] In some embodiments of the present invention, the rear lens group includes: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens and a tenth lens arranged in sequence along the propagation direction of light;

[0009] The refractive powers of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens and the tenth lens are positive, positive, positive, negative, positive, negative, positive, positive, positive, positive, negative, respectively;

[0010] The first lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens and the tenth lens are all spherical lenses, and the second lens is an aspherical lens.

[0011] In some embodiments of the present invention, the third lens and the fourth lens are cemented together to form a first doublet lens group; the Abbe number of the third lens is greater than the Abbe number of the fourth lens, and the refractive index of the third lens is less than the refractive index of the fourth lens;

[0012] The fifth lens, the sixth lens and the seventh lens are cemented together to form a triplet lens group; the Abbe numbers of the fifth lens and the seventh lens are greater than the Abbe number of the sixth lens, and the refractive indexes of the fifth lens and the seventh lens are less than the refractive index of the sixth lens;

[0013] The ninth lens and the tenth lens are cemented together to form a second doublet lens group; the Abbe number of the ninth lens is smaller than the Abbe number of the tenth lens, and the refractive index of the ninth lens is greater than the refractive index of the tenth lens.

[0014] In some embodiments of the present invention, the Abbe number and refractive index of the third lens satisfy:

[0015] 35<Vd3<90;

[0016] Nd3>1.4;

[0017] Wherein, Vd3 represents the Abbe number of the third lens, and Nd3 represents the refractive index of the third lens;

[0018] The Abbe number and refractive index of the sixth lens satisfy:

[0019] 15<Vd6<300;

[0020] Nd6>1.85;

[0021] Wherein, Vd6 represents the Abbe number of the sixth lens, and Nd6 represents the refractive index of the sixth lens;

[0022] The Abbe number and refractive index of the ninth lens and the tenth lens both satisfy:

[0023] 35<Vd<90;

[0024] Nd>1.8;

[0025] Wherein, Vd represents the Abbe number of the ninth lens or the tenth lens, and Nd represents the refractive index of the ninth lens or the tenth lens.

[0026] In some embodiments of the present invention, the middle lens group includes: an eleventh lens, a twelfth lens, and a thirteenth lens arranged in sequence along the propagation direction of light;

[0027] The refractive powers of the eleventh lens, the twelfth lens and the thirteenth lens are positive, positive and negative respectively;

[0028] The eleventh lens and the twelfth lens are both spherical lenses, and the thirteenth lens is an aspherical lens.

[0029] In some embodiments of the present invention, the front lens group includes: a fourteenth lens and a fifteenth lens sequentially arranged along the propagation direction of light;

[0030] The refractive powers of the fourteenth lens and the fifteenth lens are negative and negative respectively;

[0031] The fourteenth lens is a spherical lens, and the fifteenth lens is an aspherical lens.

[0032] In some embodiments of the present invention, the reflector is a concave aspheric reflector or a free-form reflector.

[0033] In some embodiments of the present invention, the projection lens satisfies:

[0034] 0.9<L1 / L2<1.5;

[0035] 0.1<BFL / L2<0.4;

[0036] Wherein, L1 represents the total length of the refractive system, L2 represents the distance between the refractive system and the reflective system, and BFL represents the back working distance of the projection lens.

[0037] In some embodiments of the present invention, the projection lens satisfies:

[0038] 1<|FB / F|<15;

[0039] 5<|FM / F|<150;

[0040] 5<|FF / F|<100;

[0041] 5<|FC / F|<100;

[0042] Among them, F represents the equivalent focal length of the projection lens, FB represents the equivalent focal length of the rear lens group, FM represents the equivalent focal length of the middle lens group, FF represents the equivalent focal length of the front lens group, and FC represents the equivalent focal length of the reflection system.

[0043] An embodiment of the present invention further provides a projection system, comprising:

[0044] A laser light source device, used for emitting projection light;

[0045] An illumination system, located at the light-emitting side of the laser light source device; the illumination system comprises a light homogenizing element and a light modulation device;

[0046] A projection lens is located at the light output side of the light modulation device; the projection lens is the projection lens according to any one of claims 1 to 9.

[0047] In the projection lens and projection system provided by the embodiments of the present invention, the projection lens includes a refractive system and a reflective system, and the refractive system includes a rear lens group, a middle lens group, and a front lens group. By reasonably optimizing the number, size, surface shape and other parameters of the lenses in the projection lens, the projection ratio of the projection lens can be reduced to 0.19-0.22, thereby further reducing the projection distance when projecting the same size of the picture. When adjusting the size of the picture, by adjusting the position of the middle lens group and the distance between the projection lens and the projection screen, clear imaging in various sizes of 88 inches to 120 inches can be achieved. The projection lens includes two double-cemented lens groups, one triple-cemented lens group and three aspherical lenses, with a simple structure, and can be specially optimized for chromatic aberration of three-color lasers, and the chromatic aberration range is controlled within 0.3pixel. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] 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.

[0049] Figure 1 A schematic diagram of the structure of a projection system provided by an embodiment of the present invention;

[0050] Figure 2 A schematic diagram of a method for determining a projection ratio provided by an embodiment of the present invention;

[0051] Figure 3 A schematic diagram of the structure of a projection device provided by an embodiment of the present invention;

[0052] Figure 4 A schematic diagram of a partial structure of a projection device provided by an embodiment of the present invention;

[0053] Figure 5 One of the structural schematic diagrams of the projection lens provided by an embodiment of the present invention;

[0054] Figure 6 A second structural schematic diagram of a projection lens provided by an embodiment of the present invention;

[0055] Figure 7 A third structural schematic diagram of a projection lens provided by an embodiment of the present invention;

[0056] Figure 8 A ray tracing diagram of a projection lens provided by an embodiment of the present invention;

[0057] Fig. 9 A vertical axis chromatic aberration curve diagram provided by an embodiment of the present invention;

[0058] Fig.10 A light fan diagram provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0059] 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 using 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 proportions.

[0060] Projection display is a technology that uses a plane image information to control the light source, and uses an optical system and a projection space to magnify the image and display it on a projection screen. A projection system generally includes a projection device that can emit projection light. According to the type of projection system, a front projection system is generally also equipped with a projection screen. The embodiment of the present invention specifically describes the structure of the projection device by taking a front projection system as an example.

[0061] Figure 1 A schematic diagram of the structure of a projection system provided by an embodiment of the present invention.

[0062] like Figure 1 As shown, the projection system includes: a projection device 1 and a projection screen 2. The projection device 1 emits projection light to the projection screen 2, and the projection screen 2 is arranged facing the audience. After receiving the projection light, the projection screen 2 can reflect the incident projection light toward the audience, so that the audience facing the projection screen 2 can watch the image on the projection screen 2.

[0063] According to the projection ratio, projection equipment can be divided into long-throw, short-throw and ultra-short-throw projection equipment. Figure 2 Schematic diagram of a method for determining a projection ratio according to an embodiment of the present invention. Figure 2As shown in the figure, the projection ratio refers to the ratio s / w of the projection distance s and the projection screen width w. For ultra-short-throw projection equipment, a larger projection image can be obtained at a shorter projection distance, so it is very suitable for home projection display.

[0064] The projection ratio s / d of ultra-short-throw projection equipment is usually below 0.4. The projection ratios of current ultra-short-throw projection equipment are mostly concentrated in the range of 0.22 to 0.25 and cannot be further reduced, which still results in a long distance between the projection equipment and the projection screen, which will occupy a large space, and the display screen size is single, mostly concentrated below 90 inches.

[0065] In order to achieve high-quality image display, the projection system can be equipped with a laser light source. Laser has high color purity and a large color gamut, so it can reproduce the color of the projected image more realistically and improve the audience's viewing experience. However, when the current projection equipment is used with a laser light source for image display, there is still a problem of color smear at the edge of the display image.

[0066] In view of this, an embodiment of the present invention provides a projection lens and a projection system, which can further reduce the projection ratio and improve the image quality.

[0067] The projection system includes a projection device, Figure 3 Schematic diagram of the structure of the projection device provided by the embodiment of the present invention. Figure 3 As shown, the projection device includes: a laser light source device 11, an illumination system 12 and a projection lens 13. The illumination system 12 is located at the light-emitting side of the laser light source device 11, and is used to shape and homogenize the laser light beam emitted by the laser light source device 11 into a light beam that meets the incident requirements of the light modulator and enters the light modulator; the projection lens 13 is located at the light-emitting side of the light modulator, and is used to receive the projection light beam emitted by the light modulator and perform imaging.

[0068] The laser light source device 11 can use a monochromatic laser or a laser that emits lasers of multiple colors or multiple lasers that emit lasers of different colors. When the laser light source device 11 uses a monochromatic laser, 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 sequence. When the laser light source device 11 uses a laser 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 sequence.

[0069] Figure 4 A schematic diagram of a partial structure of a projection device provided in an embodiment of the present invention.

[0070] In some embodiments, Figure 4As shown, the laser light source device may include three lasers 111, and the three lasers 111 emit red laser, green laser and blue laser respectively. In order to combine the three primary color lasers, a light combining element 112 may be used to combine the laser beams emitted by the three lasers 111. The light combining element 112 may be arranged at the intersection of the laser beams emitted by the laser 111, so that two laser beams of different colors are first combined, and then the combined laser beam is combined with a laser beam of another color, thereby achieving light combination.

[0071] The embodiment of the present invention only uses the laser light source device using three array lasers as an example for illustration. In a specific implementation, the laser light source device may also use a laser that simultaneously emits three primary color lasers, such as an MCL laser.

[0072] In addition, a lens or lens group such as a converging lens 113 may be provided in the laser light source device to converge the combined laser beams so that the combined beams can completely enter the light homogenizing element.

[0073] like Figure 3 As shown, the lighting system 12 is located on the light-emitting side of the laser light source device 11. On the one hand, the lighting system 12 collimates the output light of the laser light source device 11, and on the other hand, it can shape and homogenize the light beam emitted by the laser light source device 11, and finally enter the light modulation device at a suitable angle.

[0074] like Figure 4 As shown, the lighting system 12 at least includes a light homogenizing element 121 and a light modulator 122. The projection device provided in the embodiment of the present invention is based on a digital light processing (DLP) architecture. The light modulator 122 can use a digital micromirror (DMD). The surface of the DMD includes a large number of tiny reflectors, each of which can be driven to deflect individually. By controlling the deflection angle of the DMD, the brightness of the outgoing light can be controlled, thereby achieving modulation of the incident light and generating a display image. The light homogenizing element 121 can use a light pipe, etc., to homogenize the incident laser beam, so that the size of the light beam incident to the light modulator 122 meets the size of the light modulator 122 and the energy distribution is more uniform.

[0075] like Figure 4 As shown, the surface of the DMD (light modulator 122) usually has a protective glass 123, and the modulated projection light emitted by the DMD needs to pass through the protective glass 123. Therefore, when optically designing the projection lens 13, the influence of the protective glass 123 on the light path also needs to be considered.

[0076] In addition, a total reflection prism 124 can be arranged before the optical path of the DMD (light modulator 122), and the total reflection prism 124 can separate the illumination light beam and the projection light beam. After the homogenized light beam is incident on the total reflection prism 124, it will be totally reflected by the total reflection prism 124 toward the light modulator 122. After the light modulator 122 modulates the incident light beam, it will be incident on the total reflection prism 124 again, and then be incident on the projection lens by the total reflection prism 124.

[0077] When the projection lens 13 is optically designed, the display surface of the light modulator 122 can be used as the image surface, and the plane where the projection screen is located can be used as the object surface for optical design. The light emitted from the display surface of the light modulator 122 needs to pass through the protective glass 123, the total reflection prism 124, and the projection lens. Therefore, when the projection lens is optically designed, the influence of the light passing through the protective glass 123 and the total reflection prism 124 needs to be considered.

[0078] As a core component in projection equipment, projection lenses are difficult to design and manufacture. Currently, projection systems such as home laser TVs all use ultra-short-throw projection lenses. Ultra-short-throw projection lenses are very difficult to design due to their short projection distance, large field of view, and high imaging requirements. The embodiment of the present invention reasonably optimizes the projection lens based on the above optical system, thereby further reducing the projection ratio of the projection equipment.

[0079] Figure 5 This is one of the structural schematic diagrams of the projection lens provided by an embodiment of the present invention.

[0080] like Figure 5 As shown, the projection lens includes: a refraction system 131 and a reflection system 132 which are sequentially arranged along the propagation direction of the projection light emitted by the light modulator 122. The refraction system 131 includes three lens groups, a rear lens group 131B, a middle lens group 131M and a front lens group 131F which are sequentially arranged in a direction gradually away from the light modulator 122. The reflection system 132 includes a reflector.

[0081] The rear mirror group 131B, the middle mirror group 131M, the front mirror group 131F and the reflection system 132 are on the same principal optical axis. The projection lens provided in the embodiment of the present invention is a secondary imaging architecture. After the reflected light beam of the light modulator 122 passes through the refractive system 131, a first imaging is performed between the reflection system 132 and the refractive system 131. After the first imaging is reflected by the reflector (reflective system 132), a second imaging is performed on the projection screen.

[0082] By optimizing the number, size, and surface shape of the lenses in the projection lens, the projection ratio of the projection lens can be reduced to 0.19 to 0.22, thereby further reducing the projection distance when projecting the same size of the screen. When adjusting the screen size, based on the 0.47-inch DMD, by adjusting the position of the middle group lens group and the distance between the projection lens and the projection screen, clear imaging can be achieved in sizes from 88 inches to 120 inches, in order to meet the demand for gradually larger display screens.

[0083] Specifically, if Figure 5 As shown, along the direction gradually away from the light modulation device 122, the rear lens group 131B includes: a first lens l1, a second lens l2, a third lens l3, a fourth lens l4, a fifth lens l5, a sixth lens l6, a seventh lens l7, an eighth lens l8, a ninth lens l9 and a tenth lens l10; the refractive powers of the first lens l1, the second lens l2, the third lens l3, the fourth lens l4, the fifth lens l5, the sixth lens l6, the seventh lens l7, the eighth lens l8, the ninth lens l9 and the tenth lens l10 are positive, positive, positive, negative, positive, negative, positive, positive, positive, positive and negative respectively.

[0084] Among them, the first lens l1, the third lens l3, the fourth lens l4, the fifth lens l5, the sixth lens l6, the seventh lens l7, the eighth lens l8, the ninth lens l9 and the tenth lens l10 are all spherical lenses, and the second lens l2 is an aspherical lens. The second lens l2 can be a biconvex aspherical lens, and an axisymmetric aspherical lens, which is used to improve field curvature and astigmatism.

[0085] like Figure 5 As shown, the third lens l3 and the fourth lens l4 are cemented to form a first double cemented lens group a1; wherein the Abbe number of the third lens l3 is greater than the Abbe number of the fourth lens l4, and the refractive index of the third lens l3 is less than the refractive index of the fourth lens l4. The first double cemented lens group a1 can improve the coma aberration of different spectra of the projection lens and correct the astigmatism of the projection lens.

[0086] The fifth lens l5, the sixth lens l6 and the seventh lens l7 are cemented to form a triplet lens group b1; wherein the Abbe numbers of the fifth lens l5 and the seventh lens l7 are greater than the Abbe number of the sixth lens l6, and the refractive indexes of the fifth lens l5 and the seventh lens l7 are less than the refractive index of the sixth lens l6. The triplet lens group b1 is mainly used to correct the residual vertical axis chromatic aberration and spherical aberration of the projection lens.

[0087] The ninth lens l9 and the tenth lens l10 are cemented to form a second doublet lens group a2, wherein the Abbe number of the ninth lens l9 is smaller than the Abbe number of the tenth lens l10, and the refractive index of the ninth lens l9 is larger than the refractive index of the tenth lens l10. The second doublet lens group a2 is mainly used to correct the astigmatism and axial chromatic aberration of the projection lens.

[0088] In a specific implementation, the Abbe number and the refractive index of the third lens L3 satisfy:

[0089] 35<Vd3<90;

[0090] Nd3>1.4;

[0091] Wherein, Vd3 represents the Abbe number of the third lens l3, and Nd3 represents the refractive index of the third lens l3;

[0092] The Abbe number and refractive index of the sixth lens l6 satisfy:

[0093] 15<Vd6<300;

[0094] Nd6>1.85;

[0095] Wherein, Vd6 represents the Abbe number of the sixth lens l6, and Nd6 represents the refractive index of the sixth lens l6;

[0096] The Abbe numbers and refractive indices of the ninth lens element l9 and the tenth lens element l10 both satisfy:

[0097] 35<Vd<90;

[0098] Nd>1.8;

[0099] Wherein, Vd represents the Abbe number of the ninth lens l9 or the tenth lens l10, and Nd represents the refractive index of the ninth lens l9 or the tenth lens l10.

[0100] When performing optical design, suitable materials can be selected according to the above value range to process doublet and triplet lens groups.

[0101] The rear lens group 131B includes two doublet lens groups, one triplet lens group, one glass aspherical lens and two single lenses. It has a simple structure and can be specially optimized for chromatic aberration of three-color lasers, controlling the chromatic aberration range to 0.3 pixel.

[0102] like Figure 5 As shown, along the direction gradually away from the rear lens group, the middle lens group 131M includes: an eleventh lens 111, a twelfth lens 112 and a thirteenth lens 113; the refractive powers of the eleventh lens 111, the twelfth lens 112 and the thirteenth lens 113 are positive, positive and negative respectively.

[0103] The eleventh lens l11 and the twelfth lens l12 are both spherical lenses, and the thirteenth lens l13 is an aspherical lens. The thirteenth lens l13 may be a concave-convex aspherical lens, and an axisymmetric aspherical lens, for improving astigmatism.

[0104] The middle lens group 131M includes 3 lenses, including 1 plastic aspherical lens and 2 glass spherical lenses. Through displacement adjustment, focusing imaging of different projection sizes can be achieved.

[0105] like Figure 5 As shown, along the direction gradually away from the middle lens group, the front lens group 131F includes: a fourteenth lens 114 and a fifteenth lens 115; the refractive powers of the fourteenth lens 114 and the fifteenth lens 115 are negative and negative respectively.

[0106] The fourteenth lens l14 is a spherical lens, and the fifteenth lens l15 is an aspherical lens. The fifteenth lens l15 can be a biconcave aspherical lens, and an axisymmetric aspherical lens, which is used to improve astigmatism and field curvature.

[0107] The front lens group 131F includes two lenses, one plastic aspherical lens and one glass spherical lens. The positions of the lenses of the front lens group 131F relative to the reflection system are fixed.

[0108] like Figure 5 As shown, the reflection system 132 includes a reflection mirror, which is a concave aspheric reflection mirror or a free-form reflection mirror. The reflection mirror is placed on the light-emitting side of the front group mirror set 131F of the refractive system 131 to reflect the imaging light beam passing through the refractive system 131.

[0109] The embodiment of the present invention corrects the aberration of a large field of view through an aspheric lens and a reflector, thereby improving the resolution capability of the projection lens, thereby achieving high-resolution imaging quality. The overall structure of the projection lens includes two doublet lens groups, one triplet lens group, one glass aspheric lens, two plastic aspheric lenses, and no cutting lens, which greatly reduces the complexity of the projection lens.

[0110] Figure 6 The second structural schematic diagram of the projection lens provided by the embodiment of the present invention.

[0111] like Figure 6 As shown, the projection lens satisfies:

[0112] 0.9<L1 / L2<1.5;

[0113] 0.1<BFL / L2<0.4;

[0114] Wherein, L1 represents the total length of the refractive system 131, L2 represents the distance between the refractive system 131 and the reflective system 132, and BFL represents the back working distance of the projection lens, that is, the distance from the light modulation device 122 to the first lens l1.

[0115] By controlling the length of the refraction system 131, the distance between the refraction system and the reflection system 132, and the distance between the refraction system 131 and the light modulation device 122 within the above range, the total length of the projection lens can be controlled not to be too large, thereby controlling the volume of the projection lens and preventing the projection optical machine from occupying too much space in the projection equipment.

[0116] The projection lens also meets the following requirements:

[0117] 1<|FB / F|<15;

[0118] 5<|FM / F|<150;

[0119] 5<|FF / F|<100;

[0120] 5<|FC / F|<100;

[0121] Among them, F represents the equivalent focal length of the projection lens, FB represents the equivalent focal length of the rear lens group 131B, FM represents the equivalent focal length of the middle lens group 131M, FF represents the equivalent focal length of the front lens group 131F, and FC represents the equivalent focal length of the reflection system 132.

[0122] In the projection lens provided by the embodiment of the present invention, the refractive system 131 and the reflective system 132 generate positive refractive power. By centrally controlling the projection lens, the rear lens group 131B, the middle lens group 131M, the front lens group 131F and the reflective system 132 within the above range, the optical power can be reasonably allocated to achieve clear imaging that meets the original optical design.

[0123] Figure 7 The third structural schematic diagram of the projection lens provided by the embodiment of the present invention.

[0124] In some embodiments, Figure 7 As shown, the projection device further includes an image shifting lens group 125, which is located between the light modulating device 122 and the projection lens 13. The image shifting lens group 125 may include a flat glass, which may vibrate at a high frequency, and the vibration direction may generally be along the diagonal direction of the projected image, thereby improving the resolution of the projected image without changing the physical resolution of the projection system.

[0125] In some embodiments, the parameters such as the surface shape, material, and spacing of each optical element in the projection lens provided by the embodiments of the present invention are shown in the following table:

[0126]

[0127]

[0128] Based on the above parameters, the projection lens is an ultra-short focal length lens. The projection ratio of the projection lens is 0.19 - 0.22, the effective focal length is 2.906 mm, the offset of the projection lens, i.e., the offset range between the projection lens and the center of the light modulation device, is 142% < offset < 148%, the resolution of the projection lens can reach 93 lp / mm, and the projection screen size is 88 inches - 120 inches.

[0129] In the embodiment of the present invention, ray tracing is also performed on the projection lens and image quality evaluation simulation of the projection lens is carried out. Figure 8 It is the ray tracing diagram of the projection lens provided by the embodiment of the present invention; Fig. 9 It is the vertical chromatic aberration curve diagram provided by the embodiment of the present invention; Fig.10 It is the ray fan diagram provided by the embodiment of the present invention.

[0130] As Figure 8 shown, the projection light emitted by the projection device 1 is emitted towards the projection screen 2. On the premise that there is a small projection distance between the projection device 1 and the projection screen 2, large-size image display can be realized. The projection ratio of the projection device in the embodiment of the present invention can be reduced to 0.19 - 0.22.

[0131] Fig. 9 shows the vertical chromatic aberration when the light rays with wavelengths of 0.643 μm, 0.525 μm, and 0.465 μm are imaged within a certain field of view. Among them, the abscissa reflects the magnitude of the vertical chromatic aberration, with the unit of μm, and the ordinate is the field angle. The dotted line in the figure is the range of the Airy disk, and from Fig. 9 it can be seen that within the range of the Airy disk, the vertical chromatic aberration of the image formed by the projection lens is within a reasonable range.

[0132] Fig.10 shows the image difference values between the light rays with wavelengths of 0.643 μm, 0.525 μm, and 0.465 μm and the principal wavelength light ray in the horizontal and vertical axes under 10 normalized field of view conditions. The two graphs in each field of view are the horizontal and vertical axes that are symmetric about the optical axis in the meridional direction and the sagittal direction of the projection lens; the horizontal axis direction in each graph is the pupil height position under this field of view condition, and the vertical axis direction is the error between the light rays of each wavelength and the principal ray. From Fig.10 it can be seen that the curves of different wavelengths have a high degree of coincidence under each field of view, and the maximum value on the vertical axis is also within an acceptable range. By adopting the above projection lens architecture provided by the embodiment of the present invention, chromatic aberration can be effectively improved and the display effect can be optimized.

[0133] Based on the same inventive concept, an embodiment of the present invention further provides a projection system, which may include a projection device 1 and a projection screen 2. Figure 3 As shown, the projection device includes a laser light source device 11, an illumination system 12 and a projection lens 13. The projection lens 13 includes a refraction system and a reflection system, and the refraction system includes a rear group lens group, a middle group lens group and a front group lens group. The projection lens 13 adopts a secondary imaging architecture. After the reflected light beam of the light modulator passes through the refraction system, a first imaging is performed between the reflection system and the refraction system. After the first imaging is reflected by the reflection system, a second imaging is performed on the projection screen. By reasonably optimizing the number, size, surface shape and other parameters of the lens in the projection lens, the projection ratio of the projection lens can be reduced to 0.19-0.22, thereby further reducing the projection distance when projecting the same size of the screen. When adjusting the screen size, based on a 0.47-inch DMD, by adjusting the position of the middle group lens group and the distance between the projection lens and the projection screen, clear imaging in various sizes of 88 inches to 120 inches can be achieved to meet the demand for gradually larger display screens. The projection lens includes two doublet lens groups, one triplet lens group and three aspherical lenses. It has a simple structure and can be specially optimized for chromatic aberration of three-color lasers, controlling the chromatic aberration range within 0.3 pixel.

[0134] According to the first inventive concept, the projection lens includes a refraction system and a reflection system arranged in sequence along the propagation direction of the projection light emitted by the light modulator. The refraction system includes three lens groups, a rear lens group, a middle lens group, and a front lens group arranged in sequence along the direction gradually away from the light modulator. The reflection system includes a reflector. The projection lens is a secondary imaging architecture. After the reflected light beam of the light modulator passes through the refraction system, a first imaging is performed between the reflection system and the refraction system. After the first imaging is reflected by the reflection system, a second imaging is performed on the projection screen.

[0135] According to the second invention concept, by reasonably optimizing the number, size, surface shape and other parameters of the lens in the projection lens, the projection ratio of the projection lens can be reduced to 0.19-0.22, thereby further reducing the projection distance when projecting the same size of the screen. When adjusting the size of the screen, by adjusting the position of the middle group lens group and the distance between the projection lens and the projection screen, clear imaging in various sizes of 88 inches to 120 inches can be achieved to meet the demand for gradually larger display screens.

[0136] According to the third invention concept, the rear lens group includes: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens and a tenth lens; the refractive powers are positive, positive, positive, negative, positive, negative, positive, positive, positive, positive, negative, respectively. Among them, the first lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens and the tenth lens are all spherical lenses, and the second lens is an aspherical lens. The second lens can be a biconvex aspherical lens, and an axisymmetric aspherical lens, which is used to improve field curvature and astigmatism.

[0137] According to the fourth inventive concept, the third lens and the fourth lens are cemented together to form a first doublet lens group, which can improve the coma aberration of different spectra of the projection lens and correct the astigmatism of the projection lens.

[0138] According to the fifth inventive concept, the fifth lens, the sixth lens and the seventh lens are cemented together to form a triplet lens group for correcting the residual vertical axis chromatic aberration and spherical aberration of the projection lens.

[0139] According to the sixth inventive concept, the ninth lens and the tenth lens are cemented together to form a second doublet lens group for correcting astigmatism and axial chromatic aberration of the projection lens.

[0140] According to the seventh invention, the middle lens group includes: an eleventh lens, a twelfth lens and a thirteenth lens; the refractive powers are positive, positive and negative respectively. Among them, the eleventh lens and the twelfth lens are spherical lenses, and the thirteenth lens is an aspherical lens. The thirteenth lens can be a concave-convex aspherical lens, and an axially symmetric aspherical lens, which is used to improve astigmatism.

[0141] According to the eighth invention, the front lens group includes: a fourteenth lens and a fifteenth lens; the refractive powers are negative and negative respectively. The fourteenth lens is a spherical lens, and the fifteenth lens is an aspherical lens. The fifteenth lens can be a biconcave aspherical lens, and an axially symmetric aspherical lens, which is used to improve astigmatism and field curvature.

[0142] According to the ninth invention concept, the reflection system includes a reflection mirror, which is a concave aspheric reflection mirror or a free-form reflection mirror. The reflection mirror is placed on the light-emitting side of the front group of the refractive system to reflect the imaging light beam passing through the refractive system.

[0143] According to the tenth invention, the projection lens satisfies:

[0144] 0.9<L1 / L2<1.5;

[0145] 0.1<BFL / L2<0.4;

[0146] Wherein, L1 represents the total length of the refractive system, L2 represents the distance between the refractive system and the reflective system, and BFL represents the back working distance of the projection lens, that is, the distance from the light modulation device to the first lens.

[0147] According to the eleventh invention, the projection lens further satisfies:

[0148] 1<|FB / F|<15;

[0149] 5<|FM / F|<150;

[0150] 5<|FF / F|<100;

[0151] 5<|FC / F|<100;

[0152] Among them, F represents the equivalent focal length of the projection lens, FB represents the equivalent focal length of the rear lens group, FM represents the equivalent focal length of the middle lens group, FF represents the equivalent focal length of the front lens group, and FC represents the equivalent focal length of the reflection system.

[0153] 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.

[0154] 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: A refraction system and a reflection system are arranged in sequence along the propagation direction of light; Wherein, the refraction system comprises: a rear lens group, a middle lens group and a front lens group arranged in sequence along the propagation direction of light; the rear lens group comprises two doublet lens groups and one triplet lens group; The reflection system includes a reflector; The projection ratio of the projection lens is 0.19-0.

22.

2. The projection lens according to claim 1, wherein: The rear lens group includes: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens and a tenth lens arranged in sequence along the propagation direction of light; The refractive powers of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens and the tenth lens are positive, positive, positive, negative, positive, negative, positive, positive, positive, positive, negative, respectively; The first lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens and the tenth lens are all spherical lenses, and the second lens is an aspherical lens.

3. The projection lens according to claim 2, wherein: The third lens and the fourth lens are glued together to form a first double glued lens group; the Abbe number of the third lens is greater than the Abbe number of the fourth lens, and the refractive index of the third lens is less than the refractive index of the fourth lens; The fifth lens, the sixth lens and the seventh lens are cemented together to form a triplet lens group; the Abbe numbers of the fifth lens and the seventh lens are greater than the Abbe number of the sixth lens, and the refractive indexes of the fifth lens and the seventh lens are less than the refractive index of the sixth lens; The ninth lens and the tenth lens are cemented together to form a second doublet lens group; the Abbe number of the ninth lens is smaller than the Abbe number of the tenth lens, and the refractive index of the ninth lens is greater than the refractive index of the tenth lens.

4. The projection lens according to claim 3, wherein: The Abbe number and refractive index of the third lens satisfy: 35<Vd3<90; Nd3>1.4; Wherein, Vd3 represents the Abbe number of the third lens, and Nd3 represents the refractive index of the third lens; The Abbe number and refractive index of the sixth lens satisfy: 15<Vd6<300; Nd6>1.85; Wherein, Vd6 represents the Abbe number of the sixth lens, and Nd6 represents the refractive index of the sixth lens; The Abbe number and refractive index of the ninth lens and the tenth lens both satisfy: 35<Vd<90; Nd>1.8; Wherein, Vd represents the Abbe number of the ninth lens or the tenth lens, and Nd represents the refractive index of the ninth lens or the tenth lens.

5. The projection lens according to claim 1, wherein: The middle lens group comprises: an eleventh lens, a twelfth lens and a thirteenth lens arranged in sequence along the propagation direction of light; The refractive powers of the eleventh lens, the twelfth lens and the thirteenth lens are positive, positive and negative respectively; The eleventh lens and the twelfth lens are both spherical lenses, and the thirteenth lens is an aspherical lens.

6. The projection lens according to claim 1, wherein: The front lens group includes: a fourteenth lens and a fifteenth lens arranged in sequence along the propagation direction of light; The refractive powers of the fourteenth lens and the fifteenth lens are negative and negative respectively; The fourteenth lens is a spherical lens, and the fifteenth lens is an aspherical lens.

7. The projection lens according to claim 1, wherein: The reflecting mirror is a concave aspherical reflecting mirror or a free-form reflecting mirror.

8. The projection lens according to claim 1, wherein: The projection lens meets the following requirements: 0.9<L1 / L2<1.5; 0.1<BFL / L2<0.4; Wherein, L1 represents the total length of the refractive system, L2 represents the distance between the refractive system and the reflective system, and BFL represents the back working distance of the projection lens.

9. The projection lens according to claim 1, wherein: The projection lens meets the following requirements: 1<|FB / F|<15; 5<|FM / F|<150; 5<|FF / F|<100; 5<|FC / F|<100; Among them, F represents the equivalent focal length of the projection lens, FB represents the equivalent focal length of the rear lens group, FM represents the equivalent focal length of the middle lens group, FF represents the equivalent focal length of the front lens group, and FC represents the equivalent focal length of the reflection system.

10. A projection system, characterized in that: include: A laser light source device, used for emitting projection light; An illumination system, located at the light-emitting side of the laser light source device; the illumination system comprises a light homogenizing element and a light modulation device; A projection lens is located at the light output side of the light modulation device; the projection lens is the projection lens according to any one of claims 1 to 9.

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