Projection lens and projection system

Abstract

The invention discloses a projection lens and a projection system, and the projection lens comprises a first lens group, a second lens group, a third lens group, a fourth lens group, a fifth lens group, a sixth lens group and a seventh lens group which are coaxially arranged. Continuous zooming can be realized by adjusting the relative distances of the first lens group, the second lens group, the third lens group, the fourth lens group, the fifth lens group, the sixth lens group and the seventh lens group, so that the size of a projection image on a projection surface is changed.

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 magnifies and displays image information using an optical system and a projection space. The projection system uses an optical imaging system to complete the display of images, and the projection lens greatly affects the application scenarios and imaging quality of the projection system.

[0003] With the rapid development of projection technology, the application demand patterns are becoming more and more diverse. In order to meet the requirements of different application scenarios, in some cases, it is necessary for the projection lens to be able to display images of different sizes. At the same time, how to maintain a better display effect of the image while the image size changes is a problem worthy of attention. Summary of the Invention

[0004] In a first aspect of an embodiment of the present invention, a projection lens is provided, including: a first lens group, a second lens group, a third lens group, a fourth lens group, a fifth lens group, a sixth lens group, and a seventh lens group that are coaxially arranged;

[0005] Projection light enters from one side of the seventh lens group and sequentially passes through the seventh lens group, the sixth lens group, the fifth lens group, the fourth lens group, the third lens group, the second lens group, and the first lens group for imaging;

[0006] The distance from the projection lens to the projection surface remains unchanged, and the size of the projection image on the projection surface is changed by adjusting the relative distances of the first lens group, the second lens group, the third lens group, the fourth lens group, the fifth lens group, the sixth lens group, and the seventh lens group.

[0007] In some embodiments of the present invention, the optical power of the first lens group is negative, the optical power of the second lens group is negative, the optical power of the third lens group is negative, the optical power of the fourth lens group is positive, the optical power of the fifth lens group is positive, the optical power of the sixth lens group is negative, and the optical power of the seventh lens group is positive.

[0008] In some embodiments of the present invention, the first lens group includes: a first lens;

[0009] The second lens group includes: a second lens;

[0010] The third lens group includes: a third lens and a fourth lens that are sequentially arranged along the direction gradually away from the second lens group;

[0011] The fourth lens group includes: a fifth lens;

[0012] The fifth lens group includes: a sixth lens;

[0013] The sixth lens group includes: a seventh lens, an eighth lens, a ninth lens, and a tenth lens that are sequentially arranged along a direction gradually away from the fifth lens group;

[0014] The seventh lens group includes: an eleventh lens and a twelfth lens that are sequentially arranged along a direction gradually away from the sixth lens group.

[0015] In some embodiments of the present invention, the first lens and the eleventh lens are aspherical lenses, and the remaining lenses are spherical lenses.

[0016] In some embodiments of the present invention, the seventh lens, the eighth lens, and the ninth lens are cemented to each other.

[0017] In some embodiments of the present invention, the projection ratio of the projection lens varies in a range of 0.68 to 1.2;

[0018] The size of the image projected by the projection lens on the projection surface is 80 inches to 140 inches;

[0019] The focal length of the projection lens varies in a range of 7.08 mm to 11.88 mm, and the zoom ratio is 1.7 times.

[0020] In some embodiments of the present invention, the focal length of the projection lens satisfies:

[0021] -4.0 < f1 / fwide < -2.0;

[0022] -5.0 < f2 / fwide < -2.0;

[0023] -11.0 < f3 / fwide < -6.0;

[0024] 5.0 < f4 / fwide < 10.0;

[0025] 1.0 < f5 / fwide < 7.0;

[0026] -5.0 < f6 / fwide < -1.0;

[0027] 1.0 < f7 / fwide < 3.0;

[0028] Among them, fwide represents the focal length of the projection lens when projecting an 80-inch image, f1 represents the focal length of the first lens group, f2 represents the focal length of the second lens group, f3 represents the focal length of the third lens group, f4 represents the focal length of the fourth lens group, f5 represents the focal length of the fifth lens group, f6 represents the focal length of the sixth lens group, and f7 represents the focal length of the seventh lens group.

[0029] In some embodiments of the present invention, when the size of the projected image on the projection surface changes from large to small, the distance between the first lens group and the second lens group gradually increases, the distance between the second lens group and the third lens group gradually increases, the distance between the third lens group and the fourth lens group first decreases and then increases, the distance between the fourth lens group and the fifth lens group gradually increases, the distance between the fifth lens group and the sixth lens group gradually decreases, the distance between the sixth lens group and the seventh lens group gradually decreases, and the distance between the seventh lens group and the display surface of the light modulator gradually decreases.

[0030] In some embodiments of the present invention, the range of change in the length of the projection lens along the optical axis during zooming is 123.8 mm to 170 mm.

[0031] In a second aspect of the embodiments of the present invention, there is provided a projection system, including:

[0032] A projection light source;

[0033] An illumination system located on the light output side of the projection light source; the illumination system includes a light modulator;

[0034] A projection lens, which is any of the above projection lenses; the projection lens is located on the light output side of the light modulator.

[0035] The projection lens and the projection system provided by the embodiments of the present invention include a first lens group, a second lens group, a third lens group, a fourth lens group, a fifth lens group, a sixth lens group, and a seventh lens group arranged coaxially. Without changing the projection distance, continuous zooming can be achieved by adjusting the relative distances of the first lens group, the second lens group, the third lens group, the fourth lens group, the fifth lens group, the sixth lens group, and the seventh lens group, so that the size of the projected image on the projection surface changes. Description of the Drawings

[0036] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments of the present invention. Obviously, the following introduced drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0037] Figure 1 Schematic diagram of the structure of the projection system provided by the embodiment of the present invention;

[0038] Figure 2 Schematic diagram of the imaging principle of the projection device provided by the embodiment of the present invention;

[0039] Figure 3 One of the schematic diagrams of the structure of the projection lens provided by the embodiment of the present invention;

[0040] Figure 4 Another schematic diagram of the structure of the projection lens provided by the embodiment of the present invention;

[0041] Figure 5 Optical path diagram of the projection lens at the tele end provided by the embodiment of the present invention;

[0042] Figure 6 Optical path diagram of the projection lens at the wide end provided by the embodiment of the present invention;

[0043] Figure 7 Defocus curve diagram of the projection lens when projecting an 80-inch projection image provided by the embodiment of the present invention;

[0044] Figure 8 Defocus curve diagram of the projection lens when projecting a 100-inch projection image provided by the embodiment of the present invention;

[0045] Figure 9 Defocus curve diagram of the projection lens when projecting a 120-inch projection image provided by the embodiment of the present invention;

[0046] Figure 10 Defocus curve diagram of the projection lens when projecting a 140-inch projection image provided by the embodiment of the present invention;

[0047] Figure 11 Lateral chromatic aberration diagram of the projection lens when projecting an 80-inch projection image provided by the embodiment of the present invention;

[0048] Figure 12 Lateral chromatic aberration diagram of the projection lens when projecting a 100-inch projection image provided by the embodiment of the present invention;

[0049] Figure 13 Lateral chromatic aberration diagram of the projection lens when projecting a 120-inch projection image provided by the embodiment of the present invention;

[0050] Figure 14 Lateral chromatic aberration diagram of the projection lens when projecting a 140-inch projection image provided by the embodiment of the present invention;

[0051] Figure 15 Longitudinal chromatic aberration diagram of the projection lens when projecting an 80-inch projection image provided by the embodiment of the present invention;

[0052] Figure 16 Axial chromatic aberration diagram of the projection lens provided by the embodiment of the present invention when projecting a 100-inch projection image;

[0053] Figure 17 Axial chromatic aberration diagram of the projection lens provided by the embodiment of the present invention when projecting a 120-inch projection image;

[0054] Figure 18 Axial chromatic aberration diagram of the projection lens provided by the embodiment of the present invention when projecting a 140-inch projection image;

[0055] Figure 19 Schematic diagram of the field curvature curve of the projection lens provided by the embodiment of the present invention when projecting an 80-inch projection image;

[0056] Figure 20 Schematic diagram of the field curvature curve of the projection lens provided by the embodiment of the present invention when projecting a 100-inch projection image;

[0057] Figure 21 Schematic diagram of the field curvature curve of the projection lens provided by the embodiment of the present invention when projecting a 120-inch projection image;

[0058] Figure 22 Schematic diagram of the field curvature curve of the projection lens provided by the embodiment of the present invention when projecting a 140-inch projection image;

[0059] Figure 23 Schematic diagram of the distortion curve of the projection lens provided by the embodiment of the present invention when projecting an 80-inch projection image;

[0060] Figure 24 Schematic diagram of the distortion curve of the projection lens provided by the embodiment of the present invention when projecting a 100-inch projection image;

[0061] Figure 25 Schematic diagram of the distortion curve of the projection lens provided by the embodiment of the present invention when projecting a 120-inch projection image;

[0062] Figure 26 Schematic diagram of the distortion curve of the projection lens provided by the embodiment of the present invention when projecting a 140-inch projection image;

[0063] Figure 27 One of the aberration curves of the projection lens provided by the embodiment of the present invention when projecting an 80-inch projection image;

[0064] Figure 28 Another aberration curve of the projection lens provided by the embodiment of the present invention when projecting an 80-inch projection image;

[0065] Figure 29The third aberration curve diagram of the projection lens provided by the embodiment of the present invention when projecting an 80-inch projection image;

[0066] Figure 30 The first aberration curve diagram of the projection lens provided by the embodiment of the present invention when projecting a 140-inch projection image;

[0067] Figure 31 The second aberration curve diagram of the projection lens provided by the embodiment of the present invention when projecting a 140-inch projection image;

[0068] Figure 32 The third aberration curve diagram of the projection lens provided by the embodiment of the present invention when projecting a 140-inch projection image;

[0069] Figure 33 The schematic diagram of the telecentricity curve provided by the embodiment of the present invention. Detailed implementation manners

[0070] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described below in conjunction with the drawings and embodiments. However, the exemplary embodiments can be implemented in various forms and should not be construed as 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 concept of the exemplary embodiments to those skilled in the art. The same reference numerals in the drawings represent the same or similar structures, and thus the repeated description thereof will be omitted. The words expressing positions and directions described in the present invention are all illustrated by taking the drawings as examples, but can be changed according to needs, and all the changes made are included in the protection scope of the present invention. The drawings of the present invention are only used to illustrate the relative positional relationship and do not represent the true proportion.

[0071] Projection display technology is a technology that magnifies and displays image information by using an optical system and a projection space. The projection system finally completes the display of the image by the optical imaging system. With the continuous development of projection technology, laser projection systems have been widely used in the fields of large-screen display, laser TV, digital cinema, portable projection display, etc. with unique advantages. Laser projection display can display more vivid and gorgeous dynamic images on an ultra-large screen, achieving a visual shock effect that cannot be achieved by other display technologies.

[0072] In practical applications, the projection system can be divided into a front-projection type projection system and a rear-projection type projection system. Figure 1 The structural schematic diagram of the projection system provided by the embodiment of the present invention.

[0073] As Figure 1 shown, the front-projection type projection system can include: a projection device 100 and a projection screen 200.

[0074] 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 rays, which are incident on the projection screen 200 and are reflected from the projection screen 200 towards the position where the audience is located, so that the audience can view the projection image.

[0075] Figure 2 It is a schematic diagram of the imaging principle of the projection device provided by the embodiment of the present invention.

[0076] As Figure 2 shown, the projection device includes: a projection light source 1, an illumination system 2, and a projection lens 3. Among them, the illumination system 2 is located on the light-emitting side of the projection light source 1. A light modulator 21 is provided in the illumination system 2, and the light modulator 21 is used to modulate the incident light and then emit it. The projection lens 3 is located on the light-emitting side of the light modulator 21.

[0077] The projection light source 1 can adopt a light-emitting diode (LED) light source or a laser light source. The LED light source has the advantages of low power consumption, small volume, long service life, etc., and is suitable for application scenarios such as small-size projection. The laser light source has higher brightness and better color saturation, and can optimize the display effect of the projection image.

[0078] In the embodiment of the present invention, the projection light source can adopt a laser light source. The laser light source can adopt a single-color laser or a laser that can emit multiple colors of laser or multiple lasers that emit different colors of laser. When the laser light source adopts a single-color laser, the laser display device also needs to be provided with a color wheel, and the color wheel is used for color conversion. The single-color laser and the color wheel can be used to achieve the purpose of emitting primary color lights of different colors in sequence. When the laser light source adopts a laser that can emit multiple colors of laser, it is necessary to control the laser light source to emit lasers of different colors in sequence as primary color lights. Using a three-color laser light source is beneficial to improving the color gamut of the projection image, has better color expressiveness, and can accurately reproduce the input image.

[0079] The illumination system 2 is located on the light-emitting side of the projection light source 1. On the one hand, the illumination system 2 collimates and homogenizes the light emitted by the projection light source 1, and on the other hand, it can make the light emitted by the projection light source 1 enter the light modulator 21 at an appropriate angle. The illumination system 2 can include multiple lenses or lens groups, light guide tubes, diffusion sheets, diffusion wheels and other components, which are not limited here.

[0080] The light modulator 21 is used to modulate the incident light rays to form an image. In specific implementation, the light modulator 21 can adopt a transmissive light modulator or a reflective light modulator. Figure 2The optical modulator 21 shown is a reflective optical modulator. The optical modulator 21 receives the light rays reflected by the beam splitting prism P, modulates the incident light rays, and reflects the modulated light rays. Since the optical path is folded back by the reflective optical modulator, the volume of the projection device can be reduced.

[0081] In an embodiment of the present invention, the optical modulator 21 may adopt Liquid Crystal on Silicon (LCoS) or Digital Micromirror Device (DMD).

[0082] LCoS is formed by laminating a Complementary Metal Oxide Semiconductor (CMOS) substrate and a glass substrate with a transparent electrode, and then injecting liquid crystal for encapsulation based on semiconductor technology. LCoS has characteristics such as a high aperture ratio and high resolution for each pixel, and can form high-resolution images.

[0083] The DMD includes a large number of tiny mirrors, and each tiny mirror can be individually driven to deflect. By controlling the deflection angle of the DMD, the brightness of the light rays incident on the projection lens 3 is controlled.

[0084] The beam splitting prism P is used to separate the illumination beam and the imaging beam. Since the beam emitted by the projection light source undergoes processes such as shaping and homogenization and is finally reflected by the beam splitting prism P towards the optical modulator 21, and the light rays emitted after being modulated by the optical modulator 21 will pass through the beam splitting prism P and be incident on the projection lens 3 and then emitted.

[0085] In specific implementation, an image shift component Z may also be provided on the light-emitting side of the optical modulator 21. The image polarization component Z usually adopts a flat glass, and high-frequency vibration can be used to achieve image shift, thereby realizing high-resolution image display.

[0086] After the optical modulator 21 modulates the incident light rays to form an image, the light rays are reflected towards the projection lens 3, and the projection lens 3 performs imaging, so as to project the image onto a suitable size for viewing. The specifications of the projection lens will affect the size of the projection screen and the projection distance. In practical applications, ultra-short focus, short focus, or long focus projection lenses are used according to different application scenarios.

[0087] An embodiment of the present invention provides a projection lens, which can achieve zoom imaging of images of different sizes while keeping the projection distance unchanged.

[0088] Figure 3 is one of the structural schematic diagrams of the projection lens provided by the embodiment of the present invention. Figure 4 is another structural schematic diagram of the projection lens provided by the embodiment of the present invention.

[0089] As shown in Figure 3 and Figure 4 shown, the projection lens includes: a first lens group 31, a second lens group 32, a third lens group 33, a fourth lens group 34, a fifth lens group 35, a sixth lens group 36, and a seventh lens group 37 that are coaxially arranged; an aperture s is located between the fifth lens group 35 and the sixth lens group 36. The projection light is incident from one side of the seventh lens group 37 and sequentially passes through the seventh lens group 37, the sixth lens group 36, the fifth lens group 35, the fourth lens group 34, the third lens group 33, the second lens group 32, and the first lens group 31 for imaging.

[0090] The projection distance refers to the distance from the projection lens to the projection surface. In practical applications, a front projection system can project a projection image onto a projection screen or directly onto a wall surface. Then, the distance from the projection screen or the wall surface to the projection lens is the projection distance. The projection ratio refers to the ratio of the projection distance to the width of the projection screen. Then, when the projection distance remains unchanged, a change in the size of the projection screen will cause a change in the projection ratio. The projection lens provided in the embodiment of the present invention can achieve continuous zoom by adjusting the relative distances of the first lens group, the second lens group, the third lens group, the fourth lens group, the fifth lens group, the sixth lens group, and the seventh lens group while keeping the projection distance unchanged, so that the size of the projection image on the projection surface changes.

[0091] In the embodiment of the present invention, the optical power of the first lens group 31 is negative, the optical power of the second lens group 32 is negative, the optical power of the third lens group 33 is negative, the optical power of the fourth lens group 34 is positive, the optical power of the fifth lens group 35 is positive, the optical power of the sixth lens group 36 is negative, and the optical power of the seventh lens group 37 is positive. Among them, the first transmission group 31, the second transmission group 32, and the third lens group 33 bear negative optical power, the fourth transmission group 34 and the fifth lens group 35 bear positive optical power, the second lens group 32 plays a compensating role, and the third lens group 33 and the fourth lens group 34 play a variable magnification role.

[0092] As shown in Figure 3 and Figure 4As shown in the figure, the first lens group 31 includes: the first lens l1; the second lens group 32 includes: the second lens l2; the third lens group 33 includes: the third lens l3 and the fourth lens l4 arranged in sequence along the direction gradually away from the second lens group 32; the fourth lens group 34 includes: the fifth lens l5; the fifth lens group 35 includes: the sixth lens l6; the sixth lens group 36 includes: the seventh lens l7, the eighth lens l8, the ninth lens l9 and the tenth lens l10 arranged in sequence along the direction gradually away from the fifth lens group 35; the seventh lens group 37 includes: the eleventh lens l11 and the twelfth lens l12 arranged in sequence along the direction gradually away from the sixth lens group 36. The projection lens only includes 12 lenses, which are divided into seven lens groups, and the total length of the projection lens is less than or equal to 170 mm.

[0093] Among them, the first lens l1 and the eleventh lens l11 are aspherical lenses, and the rest of the lenses are spherical lenses. In a specific implementation, the first lens l1 can adopt a plastic aspherical lens to reduce costs; the eleventh lens l11 is relatively close to the light modulator and needs to have better heat resistance, and a glass aspherical lens can be adopted.

[0094] The seventh lens l7, the eighth lens l8 and the ninth lens l9 are mutually cemented to form a triple cemented lens. Among them, the refractive index of the seventh lens l7 is greater than that of the eighth lens l8, the refractive index of the ninth lens l9 is greater than that of the eighth lens l8, the Abbe number of the seventh lens l7 is less than that of the eighth lens l8, and the Abbe number of the ninth lens l9 is less than that of the eighth lens l8. This triple cemented lens is a typical combination of old cemented lenses, which can effectively reduce the chromatic aberration of the optical system, so that the chromatic aberration of the projection lens is less than 1.7 μm when projecting projection images of different sizes. When applied to a three-color laser projection system, the chromatic aberration between the red laser and the blue laser, the chromatic aberration between the red laser and the green laser, and the chromatic aberration between the blue laser and the green laser can all be reduced to within 0.3 pixel. At the same time, the overall optical power of this triple cemented lens is positive, and the overall participation in the optical power of the optical system is small, which can effectively correct the high-order aberrations of the optical system.

[0095] In some embodiments, the light modulator 21 can adopt a 0.474-inch DMD. Then, in cooperation with the projection lens provided by the embodiments of the present invention, a projection ratio that continuously changes within the range of 0.68 to 1.2 can be realized, and projection image sizes from 80 inches to 140 inches can be realized at the same projection distance. The maximum image height is 16 mm, the total length of the projection lens is only 170 mm, and the F.NO is 2.0, which is applicable to the full-color laser spectrum, and the chromatic aberration is less than 0.3 pixel.

[0096] The projection lens can be divided into a telephoto (tele) end and a wide-angle (wide) end during the zooming process. When the projection lens is at the tele end, the projection size can reach 140 inches, and when the projection lens is at the wide end, the projection size can reach 80 inches. When the projection lens is at the tele end, its structure is shown in Figure 3 , and when the projection lens is at the wide end, its structure is shown in Figure 4 .

[0097] In some embodiments, the focal lengths of the projection lens satisfy:

[0098] -4.0 < f1 / fwide < -2.0;

[0099] -5.0 < f2 / fwide < -2.0;

[0100] -11.0 < f3 / fwide < -6.0;

[0101] 5.0 < f4 / fwide < 10.0;

[0102] 1.0 < f5 / fwide < 7.0;

[0103] -5.0 < f6 / fwide < -1.0;

[0104] 1.0 < f7 / fwide < 3.0;

[0105] Among them, fwide represents the focal length of the projection lens when projecting an 80-inch image (i.e., when the projection lens is at the wide end), f1 represents the focal length of the first lens group, f2 represents the focal length of the second lens group, f3 represents the focal length of the third lens group, f4 represents the focal length of the fourth lens group, f5 represents the focal length of the fifth lens group, f6 represents the focal length of the sixth lens group, and f7 represents the focal length of the seventh lens group.

[0106] Figure 5 is the optical path diagram of the projection lens at the tele end provided by the embodiments of the present invention, Figure 6 is the optical path diagram of the projection lens at the wide end provided by the embodiments of the present invention.

[0107] Referring to Figure 5 and Figure 6 , when the projection lens changes from the tele end to the wide end, the distance between the first lens group and the second lens group gradually increases, the distance between the second lens group and the third lens group gradually increases, the distance between the third lens group and the fourth lens group first decreases and then increases, the distance between the fourth lens group and the fifth lens group gradually increases, the distance between the fifth lens group and the sixth lens group gradually decreases, the distance between the sixth lens group and the seventh lens group gradually decreases, and the distance between the seventh lens group and the display surface of the light modulator gradually decreases.

[0108] During the zooming process of the projection lens, the variation range of the length along the optical axis (the distance between the first lens and the twelfth lens on the optical axis) is 123.8 mm to 170 mm, the focal length variation range is 7.08 mm to 11.88 mm, and the zoom ratio is 1.7 times. During the zooming process of the projection lens, the optical distortion is always less than or equal to 1%, and continuous zoom projection with a relative illumination always greater than 70% can be achieved.

[0109] In some embodiments, the surface type parameters of each optical component in the projection lens and the spacing between each optical component are as shown in the following table. It should be noted that when performing the optical design of the projection lens, the imaging position (projection surface) is used as the object surface, and the display surface of the light modulator is used as the image surface for optical design. Then, using the principle of reversibility of the optical path, projection display that meets the design size and image quality can be achieved on the object surface during design:

[0110]

[0111]

[0112] The aspheric coefficients of the first lens are as shown in the following table:

[0113]

[0114] The aspheric coefficients of the eleventh lens are as shown in the following table:

[0115]

[0116] Based on the above parameters, the projection lens satisfies: 0.68 ≤ projection ratio ≤ 1.2, 7.08 ≤ effective focal length ≤ 11.88, offset = 100% - 102%, the resolution can reach 93 lp / mm, the projectable size is 80 inches to 140 inches, and chromatic aberration ≤ 0.3 pixel.

[0117] In the embodiments of the present invention, the image quality evaluation of the projection lens for imaging with different sizes is also performed based on the above parameter optimization results.

[0118] Figure 7 、 Figure 8 、 Figure 9 and Figure 10 respectively show the defocus curves of light with wavelengths of 643 nm, 525 nm, and 465 nm at a spatial frequency of 93.0 cycles / mm in different fields of view when the projection lens projects projection screens of 80 inches, 100 inches, 120 inches, and 140 inches. The abscissa represents the defocusing position, with the unit of mm, and the ordinate represents the MTF value (Modulation), by Figures 7 - 10It can be seen that the MTF values of the light rays in different fields of view at the optical axis are all above 0.7, and the degree of image plane offset is within a reasonable range.

[0119] Figure 11 、 Figure 12 、 Figure 13 and Figure 14 respectively show the lateral chromatic aberration of the light rays with wavelengths of 643nm, 525nm, and 465nm within a certain field of view when the projection lens projects projection screens of 80 inches, 100 inches, 120 inches, and 140 inches. The abscissa represents the lateral chromatic aberration (Lateral colour) in μm, and the ordinate represents the actual imaging size (Image realsize) in mm. It can be seen from Figures 11 - 14 that the lateral chromatic aberration of the projection lens is below 1.7μm.

[0120] Figure 15 、 Figure 16 、 Figure 17 and Figure 18 respectively show the axial chromatic aberration of the light rays with wavelengths of 643nm, 525nm, and 465nm when the projection lens projects projection screens of 80 inches, 100 inches, 120 inches, and 140 inches. It can be seen from Figures 15 - 18 that the intervals between the curves corresponding to the three wavelengths are small, indicating that the axial chromatic aberration of the projection lens is small and meets the requirements.

[0121] Figure 19 、 Figure 20 、 Figure 21 and Figure 22 respectively show the field curvature curves in the meridional direction (T) and the sagittal direction (S) when the projection lens projects projection screens of 80 inches, 100 inches, 120 inches, and 140 inches. The abscissa represents the field curvature size in mm, and the ordinate represents the image height (field of view). It can be seen from Figures 19 - 22 that the field curvature of the projection lens is controlled within 0.02mm.

[0122] Figure 23 、 Figure 24 、 Figure 25 and Figure 26 respectively show the distortion curves of the projection lens at different fields of view when the projection lens projects projection screens of 80 inches, 100 inches, 120 inches, and 140 inches. The abscissa represents the distortion percentage of the imaging, and the ordinate represents the image height (field of view). It can be seen from Figures 23 - 26 that the distortion of the projection lens is controlled within 1%.

[0123] Figure 27 、 Figure 28 and Figure 29It shows the aberration curves of light with wavelengths of 643nm, 525nm, and 465nm along the tangential direction and the sagittal direction at 12 normalized fields of view when the projection lens projects an 80-inch projection screen. Figure 30 , Figure 31 and Figure 32 It shows the aberration curves of light with wavelengths of 643nm, 525nm, and 465nm along the tangential direction and the sagittal direction at 12 normalized fields of view when the projection lens projects a 140-inch projection screen. The smaller the curve fluctuation and the closer it is to the horizontal line, the smaller the aberration. It can be seen from Figures 27 - 32 that the aberration of the projection lens is small when projecting images of different sizes, and the imaging quality is good.

[0124] Figure 33 It is a schematic diagram of the telecentricity curve provided by the embodiment of the present invention.

[0125] Figure 33 It shows the bar chart of the telecentricity of the outgoing light at different fields of view, where the abscissa represents the field of view size, and the ordinate represents the angle of the outgoing light corresponding to different fields of view, that is, the telecentricity. It can be seen from Figure 33 that the telecentricity of the projection lens is less than 0.95 degrees and increases uniformly without inflection, and the system performance is good.

[0126] Based on the same inventive concept, the embodiment of the present invention also provides a projection system. As Figure 1 shown, the projection system may include a projection device 100 and a projection screen 200. The projection device includes: a projection light source 1, an illumination system 2, and a projection lens 3, where the projection lens may adopt any of the above projection lenses. The projection lens can be applied to a three-color laser projection system. On the premise that the total length of the lens does not exceed 170mm, zoom imaging from 80 inches to 140 inches can be achieved, the chromatic aberration of the three-color laser is reduced to less than 0.3 pixels, and the projection screen still has small distortion at large sizes.

[0127] According to the first inventive concept, the projection lens includes a first lens group, a second lens group, a third lens group, a fourth lens group, a fifth lens group, a sixth lens group, and a seventh lens group arranged coaxially. Without changing the projection distance, continuous zoom can be achieved by adjusting the relative distances of the first lens group, the second lens group, the third lens group, the fourth lens group, the fifth lens group, the sixth lens group, and the seventh lens group, so that the size of the projection image on the projection surface changes.

[0128] According to the second inventive concept, the optical power of the first lens group is negative, the optical power of the second lens group is negative, the optical power of the third lens group is negative, the optical power of the fourth lens group is positive, the optical power of the fifth lens group is positive, the optical power of the sixth lens group is negative, and the optical power of the seventh lens group is positive. Among them, the first transmission group, the second transmission group, and the third lens group bear negative optical power, the fourth transmission group and the fifth lens group bear positive optical power, the second lens group plays a compensating role, and the third lens group and the fourth lens group play a zooming role.

[0129] According to the third inventive concept, the first lens group includes: a first lens; the second lens group includes: a second lens; the third lens group includes: a third lens and a fourth lens arranged in sequence along the direction gradually away from the second lens group; the fourth lens group includes: a fifth lens; the fifth lens group includes: a sixth lens; the sixth lens group includes: a seventh lens, an eighth lens, a ninth lens, and a tenth lens; the seventh lens group includes: an eleventh lens and a twelfth lens. The projection lens only includes 12 lenses, which are divided into seven lens groups, and the total length of the projection lens is less than or equal to 170 mm.

[0130] According to the fourth inventive concept, the first lens and the eleventh lens are aspherical lenses, and the remaining lenses are all spherical lenses.

[0131] According to the fifth inventive concept, the seventh lens, the eighth lens, and the ninth lens are mutually cemented to form a triple cemented lens, which can effectively reduce the chromatic aberration of the optical system, so that the projection lens can meet the requirement that the chromatic aberration is less than 1.7 μm when projecting different-sized projection images. The overall optical power of this triple cemented lens is positive, and the overall participation in the optical power of the optical system is small, which can effectively correct the high-order aberration of the optical system.

[0132] According to the sixth inventive concept, when the projection lens is combined with a 0.474-inch DMD, the projection ratio can be continuously changed within the range of 0.68 to 1.2, and the projection image size can be achieved within the range of 80 inches to 140 inches at the same projection distance.

[0133] According to the seventh inventive concept, when the projection lens changes from the telephoto end to the wide-angle end, the distance between the first lens group and the second lens group gradually increases, the distance between the second lens group and the third lens group gradually increases, the distance between the third lens group and the fourth lens group first decreases and then increases, the distance between the fourth lens group and the fifth lens group gradually increases, the distance between the fifth lens group and the sixth lens group gradually decreases, the distance between the sixth lens group and the seventh lens group gradually decreases, and the distance between the seventh lens group and the display surface of the light modulator gradually decreases.

[0134] According to the eighth inventive concept, during the zooming process of the projection lens, the change range of the length along the optical axis is 123.8 mm to 170 mm, the focal length change range is 7.08 mm to 11.88 mm, and the zoom ratio is 1.7 times.

[0135] According to the ninth inventive concept, the optical distortion of the projection lens is always less than or equal to 1% during the zooming process, and continuous zoom projection with a relative illumination always greater than 70% can be achieved.

[0136] Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be construed as including the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.

[0137] 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 equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A projection lens, characterized in that, Including: A first lens group, a second lens group, a third lens group, a fourth lens group, a fifth lens group, a sixth lens group, and a seventh lens group which are coaxially arranged; Projection light enters from one side of the seventh lens group and sequentially passes through the seventh lens group, the sixth lens group, the fifth lens group, the fourth lens group, the third lens group, the second lens group, and the first lens group for imaging; The distance from the projection lens to the projection surface remains unchanged, and the size of the projection image on the projection surface is changed by adjusting the relative distances of the first lens group, the second lens group, the third lens group, the fourth lens group, the fifth lens group, the sixth lens group, and the seventh lens group.

2. The projection lens according to claim 1, characterized in that, The optical power of the first lens group is negative, the optical power of the second lens group is negative, the optical power of the third lens group is negative, the optical power of the fourth lens group is positive, the optical power of the fifth lens group is positive, the optical power of the sixth lens group is negative, and the optical power of the seventh lens group is positive.

3. The projection lens according to claim 2, characterized in that, The first lens group includes: a first lens; The second lens group includes: a second lens; The third lens group includes: a third lens and a fourth lens which are sequentially arranged along the direction gradually away from the second lens group; The fourth lens group includes: a fifth lens; The fifth lens group includes: a sixth lens; The sixth lens group includes: a seventh lens, an eighth lens, a ninth lens, and a tenth lens which are sequentially arranged along the direction gradually away from the fifth lens group; The seventh lens group includes: an eleventh lens and a twelfth lens which are sequentially arranged along the direction gradually away from the sixth lens group.

4. The projection lens according to claim 3, wherein, The first lens and the eleventh lens are aspherical lenses, and the remaining lenses are all spherical lenses.

5. The projection lens according to claim 3, characterized in that, The seventh lens, the eighth lens, and the ninth lens are mutually cemented.

6. The projection lens according to any one of claims 2 to 5, characterized in that, The variation range of the projection ratio of the projection lens is 0.68 to 1.2; The size of the image projected by the projection lens on the projection surface is 80 inches to 140 inches; The variation range of the focal length of the projection lens is 7.08 mm to 11.88 mm, and the zoom ratio is 1.7 times.

7. The projection lens according to claim 6, wherein, The focal length of the projection lens satisfies: -4.0 < f1 / fwide < -2.0; -5.0 < f2 / fwide < -2.0; -11.0 < f3 / fwide < -6.0; 5.0 < f4 / fwide < 10.0; 1.0 < f5 / fwide < 7.0; -5.0 < f6 / fwide < -1.0; 1.0 < f7 / fwide < 3.0; Wherein, fwide represents the focal length of the projection lens when projecting an 80-inch image, f1 represents the focal length of the first lens group, f2 represents the focal length of the second lens group, f3 represents the focal length of the third lens group, f4 represents the focal length of the fourth lens group, f5 represents the focal length of the fifth lens group, f6 represents the focal length of the sixth lens group, and f7 represents the focal length of the seventh lens group.

8. The projection lens according to claim 6, wherein When the size of the projected image on the projection surface changes from large to small, the distance between the first lens group and the second lens group gradually increases, the distance between the second lens group and the third lens group gradually increases, the distance between the third lens group and the fourth lens group first decreases and then increases, the distance between the fourth lens group and the fifth lens group gradually increases, the distance between the fifth lens group and the sixth lens group gradually decreases, the distance between the sixth lens group and the seventh lens group gradually decreases, and the distance between the seventh lens group and the display surface of the light modulator gradually decreases.

9. The projection lens according to claim 6, wherein, During the zooming process of the projection lens, the variation range of the length along the optical axis is 123.8 mm to 170 mm.

10. A projection system, characterized in that, Comprising: A projection light source; An illumination system located on the light-emitting side of the projection light source; the illumination system includes a light modulator; A projection lens, which is the projection lens according to any one of claims 1 to 9; the projection lens is located on the light-emitting side of the light modulator.

Images