CN114296217A - Projection lens and projection system - Google Patents
Projection lens and projection system Download PDFInfo
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- CN114296217A CN114296217A CN202111631763.2A CN202111631763A CN114296217A CN 114296217 A CN114296217 A CN 114296217A CN 202111631763 A CN202111631763 A CN 202111631763A CN 114296217 A CN114296217 A CN 114296217A
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Abstract
The invention discloses a projection lens and a projection system, comprising: a refractive system and a reflective system, the refractive system comprising: the rear lens group comprises two double-cemented lens groups and a triple-cemented lens group; the reflecting system comprises a reflecting mirror, the reflecting mirror comprises a first surface close to the front lens group and a second surface far away from the front lens group, and the second surface is used for reflecting imaging light rays of the refracting system. Two double-cemented lens group and one triple-cemented lens group are adopted to improve chromatic aberration generated by different wavelengths, so that the spectrum of the projection lens covers the range of 450 nm-645 nm. The second surface of the reflector is adopted to reflect the imaging light, so that the first surface and the second surface both participate in secondary imaging, the degree of freedom of the two surfaces is utilized to the maximum extent, the design difficulty of the two surfaces can be reduced, and the manufacturability of the reflecting system is improved.
Description
Technical Field
The invention relates to the technical field of projection display, in particular to a projection lens and a projection system.
Background
With the continuous development of projection technology, projection display products are beginning to be used as large screen products to replace televisions to reach thousands of households. As a display product for replacing a television, in order to avoid the influence of the projection lens by an object to the display effect, or to design an all-in-one machine structure, an ultra-short-focus lens is generally configured in a current household projection device. The ultra-short focal lens has short projection distance, large requirement on a view field, high imaging requirement, and high design difficulty due to the consideration of cost and miniaturization.
With the popularization and the use of three-color laser light sources, the projection wavelength is expanded from the original 620nm to 645nm, so that a projection lens designed based on the wavelength within 620nm is not applicable any more, and the problem of color cast exists in picture imaging.
Disclosure of Invention
In some embodiments of the present invention, a projection lens includes: a refractive system and a reflective system, the refractive system comprising: the rear lens group comprises two double-cemented lens groups and a triple-cemented lens group; the reflecting system comprises a reflecting mirror, the reflecting mirror comprises a first surface close to the front lens group and a second surface far away from the front lens group, and the second surface is used for reflecting imaging light rays of the refracting system. Two double-cemented lens group and one triple-cemented lens group are adopted to improve chromatic aberration generated by different wavelengths, so that the spectrum of the projection lens covers the range of 450 nm-645 nm. The double-cemented lens group and the triple-cemented lens group which are far away from the reflection system are used for improving chromatic aberration of a vertical axis of the lens, and the triple-cemented lens group corrects spherical aberration of the lens; the double-cemented lens group close to the reflection system is mainly used for correcting residual coma and field curvature of a system diaphragm. By adopting two double-cemented lens group and one triple-cemented lens group, the machining precision can be reduced on the premise of ensuring effective chromatic aberration correction, and the manufacturability design is improved.
In some embodiments of the present invention, the projection lens adopts a secondary imaging structure, after projection passes through the refraction system, primary imaging is performed between the reflection system and the refraction system, and after the primary imaging is reflected by the reflection system, secondary imaging is performed at a set position.
In some embodiments of the present invention, the catadioptric system includes a mirror for folding the optical path for imaging, thereby reducing the length and size of the projection lens. The mirrors in the reflective system include a first surface adjacent the front set of mirrors and a second surface facing away from the front set of mirrors. The second surface of the reflector is adopted to reflect the imaging light, so that the first surface and the second surface both participate in secondary imaging, the degree of freedom of the two surfaces is utilized to the maximum extent, and the design difficulty of the two surfaces can be reduced. In addition, the second surface is adopted to reflect the imaging light, so that the energy of the projection light is mainly concentrated on the second surface, and the second surface is the outer surface of the projection lens, so that the heat dissipation device is easier to arrange compared with the position of the first surface.
In some embodiments of the present invention, the reflective system, the front lens group, the middle lens group and the rear lens group are coaxially disposed. The front lens group can be movably adjusted relative to the reflecting system, and better distortion performance under different sizes is realized. By adjusting the displacement between the middle group lens and the rear group lens relative to the front group lens and the rear group lens, focusing imaging with different projection sizes can be realized. When the size of the picture is adjusted, the distance between the projection lens and the projection screen can be changed, and clear images can be obtained under various sizes.
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, an aperture stop, a seventh lens, an eighth lens and a ninth lens, which are sequentially disposed along a direction gradually approaching the reflection system. The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens and the ninth lens are all spherical lenses. The diopter of the first lens is positive, the diopter of the second lens is positive, the diopter of the third lens is negative, the diopter of the fourth lens is positive, the diopter of the fifth lens is negative, the diopter of the sixth lens is positive, the diopter of the seventh lens is positive, the diopter of the eighth lens is positive, and the diopter of the ninth lens is negative.
In some embodiments of the present invention, the second lens and the third lens are cemented together to form a double cemented lens set. The abbe number of the second lens is larger than that of the third lens; the refractive index of the second lens is smaller than that of the third lens. The fourth lens, the fifth lens and the sixth lens are mutually cemented to form a triple cemented lens group. The Abbe number of the fourth lens is larger than that of the fifth lens, and the Abbe number of the fifth lens is smaller than that of the sixth lens; the refractive index of the fourth lens is smaller than that of the fifth lens, and the refractive index of the fifth lens is larger than that of the sixth lens. The eighth lens and the ninth lens are mutually glued to form a double-glued lens group. The Abbe number of the eighth lens is smaller than that of the ninth lens; the refractive index of the eighth lens is greater than that of the ninth lens.
In some embodiments of the present invention, an aperture stop is disposed between the sixth lens and the seventh lens, which can limit the amount of light passing through the projection lens, and is adapted to the F number of the projection lens, so as to shield light rays with large aberration at the edge position.
In some embodiments of the present invention, the middle lens group includes a tenth lens element; the tenth lens is a spherical lens. The tenth lens is positive in diopter.
In some embodiments of the present invention, the front lens group includes an eleventh lens, a twelfth lens and a thirteenth lens sequentially arranged along a direction gradually approaching the reflection system. The eleventh lens and the twelfth lens are spherical lenses, and the thirteenth lens is an aspheric lens. The diopter of the eleventh lens is positive, the diopter of the twelfth lens is negative, and the diopter of the thirteenth lens is negative. The reflection system can compress the light rays in a large proportion, and the thirteenth lens close to the reflection system is arranged to be an aspheric lens, so that astigmatism can be effectively improved, and distortion can be effectively corrected.
In some embodiments of the present invention, the thirteenth lens may be an aspheric meniscus lens, and a plastic aspheric lens, and the third lens may be made of a plastic material to improve manufacturability and reduce cost due to a larger aperture of the aspheric lens near the reflective system.
In some embodiments of the present invention, the reflecting mirror in the reflecting system is a concave reflecting mirror, which is used to compress the light angle, and may be a concave-convex double-aspheric reflecting mirror or a double-free-form surface reflecting mirror. The reflection system participates in imaging, and light compression is effectively carried out so as to realize large-size image display. Distortion is inevitably generated when light is compressed in a large proportion, and therefore astigmatism and distortion can be effectively corrected by using an aspherical mirror or a free-form surface mirror. The aspheric lens and the aspheric reflector or the free-form surface reflector are adopted to correct the large field aberration, so that the resolving power of the lens is improved, and the imaging quality with high resolution is realized. The second surface of the reflector is adopted to reflect imaging light, and the concave-convex double-aspheric reflector or the double-free-form-surface reflector also participates in the chromatic aberration correction process, so that the degree of freedom and the capacity of chromatic aberration correction of the projection lens are increased.
In some embodiments of the present invention, the equivalent focal length of the projection lens, the equivalent focal length of the rear group lens, the equivalent focal length of the middle group lens, the equivalent focal length of the front group lens, and the equivalent focal length of the reflection system satisfy the following relationships:
5<|FB/F|<12；
15<|FM/F|<25；
10<|FF/F|<20；
3<|FC/F|<12；
wherein, 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.
In some embodiments of the invention, the projection ratio of the projection lens is 0.2-0.25, so that the use requirement of the ultra-short-focus projection lens is met, the distance between the projection equipment and the projection screen is greatly shortened, and the image display of 70-100 inches can be realized while the projection distance is shortened.
In some embodiments of the invention, the lengths of the refractive system and the reflective system satisfy the following relationship:
1.5<L1/L2<2；
the rear working distance of the projection lens meets the following relation:
0.35<BFL/L2<0.7；
where L1 denotes the total length of the refractive system, L2 denotes the distance between the refractive system and the reflective system, and BFL denotes the rear working distance of the projection lens.
On the premise of ensuring that the overall size of the projection lens is within an acceptable range, the rear working distance is increased, so that elements such as a beam splitter prism, an image offset mirror group and the like can be added, and the display resolution is improved.
In some first draft examples of the invention, the chromatic aberration in the 450nm to 645nm band is less than or equal to 0.3 pixel. Based on the design of the projection lens provided by the embodiment of the invention, the chromatic aberration generated by different primary colors can be effectively improved, and the spectrum is expanded to 450 nm-645 nm.
In some embodiments of the invention, a projection system comprises: the projection lens comprises a projection light source, a beam splitter prism, a light valve modulation component, an image shift mirror group and any one projection lens. The projection light source is used for emitting light with different colors according to time sequence; the beam splitting prism is positioned between the light valve modulation component and the projection lens; the beam splitter prism is used for reflecting the emergent light of the projection light source to the light valve modulation component and transmitting the emergent light of the light valve modulation component; a light valve modulation component, which is positioned on the reflection path of the beam splitter prism; the light valve modulation component is used for modulating and reflecting incident light; and the image shifting mirror group is positioned between the beam splitter prism and the projection lens and is used for shifting emergent rays.
In some embodiments of the invention, the projection screen is arranged on the side of the refraction system departing from the reflection system, the distance between the projection lens and the projection screen is relatively small, and the condition that an object enters between the projection lens and the projection screen does not exist, so that the problem that a picture is blocked is avoided, and the use space is saved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments of the present invention will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a projection lens according to an embodiment of the present invention;
fig. 2 is a lateral chromatic aberration curve of a projection lens according to an embodiment of the present invention;
FIG. 3 is a fan-plane view of light provided by an embodiment of the present invention;
FIG. 4 is a schematic diagram of a projection system according to an embodiment of the present invention;
fig. 5 is a schematic projection diagram of a projection system according to an embodiment of the present invention.
Wherein, 100-projection lens, 200-projection light source, 300-beam splitter prism, 400-light valve modulation component, 500-image shift lens group, 600-projection screen, 10 a-refraction system, 10 b-reflection system, 101-rear lens group, 102-middle lens group, 103-front lens group, 11-first lens, 12-second lens, 13-third lens, 14-fourth lens, 15-fifth lens, 16-sixth lens, 17-seventh lens, 18-eighth lens, 19-ninth lens, 110-tenth lens, 111-eleventh lens, 112-twelfth lens, 113-thirteenth lens, a 1-first double cemented lens group, a 2-third cemented lens group, a 3-second double cemented lens group, d-aperture diaphragm.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, the present invention is further described with reference to the accompanying drawings and examples. Example embodiments may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of example embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and thus their repetitive description will be omitted. The words expressing the position and direction described in the present invention are illustrated in the accompanying drawings, but may be changed as required and still be within the scope of the present invention. The drawings of the present invention are for illustrative purposes only and do not represent true scale.
With the continuous development of projection technology, projection display devices have been developed from the fields of traditional business education and the like to display products that replace televisions. The projection display is to control the light source by the plane image information, enlarge and display the image on the projection screen by using the optical system and the projection space.
At present, a projection system may adopt a Digital Light Processing (DLP) architecture, a Digital Micromirror Device (DMD) is used as a core Device, Light emitted from a projection Light source is incident on the DMD to generate an image, the emergent Light of the image generated by the DMD is incident on a projection lens, and the image is imaged by the projection lens and finally received by a projection screen.
The light emitted from the projection lens is usually projected onto a screen or a wall, and then reflected by the projection screen or the wall to enter human eyes. At present, a certain distance is needed between a projection lens and a projection screen of a household projector to enable a projection picture to be clear. However, if an object moves between the projection screen and the projection lens, the moving object will block the light emitted from the projection lens, so that the picture on the projection screen is lost, and the display effect is affected.
Therefore, the existing household projection equipment adopts an ultra-short focal lens. The ultra-short focal lens has short projection distance, large requirement on a view field, high imaging requirement, and high design difficulty due to the consideration of cost and miniaturization. With the popularization and the use of three-color laser light sources, the wavelength is expanded from the original 620nm to 645nm, so that a projection lens designed based on the wavelength within 620nm is not applicable any more, and the problem of color cast exists in picture imaging.
In view of this, embodiments of the present invention provide a projection lens, which can balance the problems of miniaturization and color shift correction of a projection system.
The light emitted by the projection light source can be modulated and then reflected to the projection lens by the DMD as a light valve modulation device, and imaging display is carried out by the projection lens.
Fig. 1 is a schematic structural diagram of a projection lens according to an embodiment of the present invention.
As shown in fig. 1, a projection lens provided in an embodiment of the present invention includes: a refractive system 10a and a reflective system 10 b.
The refraction system 10a is located on the light-emitting side of the light valve modulating component and is used for imaging the image light emitted by the light valve modulating component.
The reflection system 10b is located on a side of the refraction system 10a facing away from the light valve modulation component, i.e. the light-emitting side of the refraction system 10a, and is used for imaging the imaging light of the refraction system again and reflecting the imaging light to a set position.
The projection lens provided by the embodiment of the invention adopts a secondary imaging framework, after a light valve reflected light beam passes through the refraction system 10a, primary imaging is carried out between the reflection system 10b and the refraction system 10a, and after the primary imaging is reflected by the reflection system 10b, secondary imaging is carried out at a set position. In general, a projection screen may be disposed at a set position for receiving the imaging light of the projection lens for image display.
When the projection screen is applied specifically, the projection screen can be arranged on one side of the refraction system, which is away from the reflection system, the distance between the projection lens and the projection screen is relatively small, and the condition that an object enters between the projection lens and the projection screen does not exist, so that the problem that a picture is shielded is avoided, and the use space is saved.
As shown in fig. 1, the refractive system 10a includes: a rear group lens 101, a middle group lens 102, and a front group lens 103. Wherein, the front lens group 103 is located at a side close to the reflection system 10 b; the middle lens group 102 is located on the side of the front lens group 103 facing away from the reflection system 10 b; the rear group lens 101 is located on a side of the middle group lens 102 facing away from the front group lens 103.
The reflecting system 10b, the front group lens 103, the middle group lens 102 and the rear group lens 101 are coaxially disposed. The front group lens 103 is movably adjusted relative to the reflection system 10b, so that better distortion performance under different sizes is realized. By adjusting the displacement between the middle group lens 102 relative to the front group lens 103 and the rear group lens 101, focusing imaging of different projection sizes can be achieved. When the size of the picture is adjusted, the distance between the projection lens and the projection screen can be changed, and clear images can be obtained under various sizes.
The catadioptric system 10b includes a mirror on the light exit side of the refractive system 10a for folding the light path for imaging, thereby reducing the length and size of the projection lens. The mirrors in the reflective system comprise a first surface s1 close to the front set 103 of mirrors and a second surface s2 facing away from the front set 103 of mirrors. In the embodiment of the invention, the second surface s2 of the reflector is adopted to reflect the imaging light, so that the first surface s1 and the second surface s2 both participate in secondary imaging, the degree of freedom of the two surfaces is utilized to the maximum extent, the capability of the two surfaces for correcting chromatic aberration is fully utilized, and the design difficulty of the two surfaces can be reduced. In addition, the second surface s2 is used to reflect the image light, so that the energy of the projection light is mainly concentrated on the second surface s2, and the second surface s2 is the outer surface of the projection lens, so that it is easier to arrange a heat sink than the position of the first surface s 1.
Specifically, as shown in fig. 1, the rear lens group 101 includes a first lens 11, a second lens 12, a third lens 13, a fourth lens 14, a fifth lens 15, a sixth lens 16, an aperture stop d, a seventh lens 17, an eighth lens 18, and a ninth lens 19, which are arranged in this order in a direction gradually approaching the reflection system 10 b.
The first lens 11, the second lens 12, the third lens 13, the fourth lens 14, the fifth lens 15, the sixth lens 16, the seventh lens 17, the eighth lens 18, and the ninth lens 19 are all spherical lenses.
Diopter of the first lens 11 is positive, diopter of the second lens 12 is positive, diopter of the third lens 13 is negative, diopter of the fourth lens 14 is positive, diopter of the fifth lens 15 is negative, diopter of the sixth lens 16 is positive, diopter of the seventh lens 17 is positive, diopter of the eighth lens 18 is positive, and diopter of the ninth lens 19 is negative.
The second lens 12 and the third lens 13 are cemented with each other to constitute a first cemented doublet group a 1. The abbe number of the second lens 12 is larger than that of the third lens 13; the refractive index of the second lens 12 is smaller than that of the third lens 13. In practical application, the value range of the abbe number Vd2 of the second lens 12 is: 60 < Vd2 < 90, and the refractive index Nd2 < 1.6 of the second lens 12. When the optical design is performed, the second lens 12 and the third lens 13 may be processed by selecting appropriate materials according to the value range.
The fourth lens 14, the fifth lens 15, and the sixth lens 16 are cemented with each other to constitute a triple cemented lens group a 2. The abbe number of the fourth lens 14 is larger than that of the fifth lens 15, and the abbe number of the fifth lens 15 is smaller than that of the sixth lens 16; the refractive index of the fourth lens 14 is smaller than that of the fifth lens 15, and the refractive index of the fifth lens 15 is larger than that of the sixth lens 16. In practical application, the value range of the abbe number Vd5 of the fifth lens 15 is as follows: 20 < Vd5 < 35, and the refractive index Nd5 > 1.85 of the fifth lens 15. The value range of the abbe number Vd6 of the sixth lens 16 is: 60 < Vd6 < 90. When the optical design is performed, the fourth lens 14, the fifth lens 15, and the sixth lens 16 may be processed by selecting appropriate materials according to the value ranges.
The eighth lens 18 and the ninth lens 19 are cemented with each other to constitute a second cemented double lens group a 3. The abbe number of the eighth lens 18 is smaller than that of the ninth lens 19; the refractive index of the eighth lens 18 is larger than that of the ninth lens 19. In practical application, the value range of the abbe number Vd8 of the eighth lens 18 is: 20 < Vd8 < 35, and the refractive index Nd8 > 1.7 of the eighth lens element 18. The value range of the abbe number Vd9 of the ninth lens 19 is: 30 < Vd9 < 60. When the optical design is performed, the eighth lens 18 and the ninth lens 19 may be processed by selecting appropriate materials according to the value range.
In the embodiment of the invention, two double-cemented lens groups and one triple-cemented lens group are adopted to improve chromatic aberration generated by different wavelengths, so that the spectrum of the projection lens provided by the embodiment of the invention covers the range of 450 nm-645 nm. Wherein the first doublet lens group a1 and the triple cemented lens group a2 are used for improving chromatic aberration of a vertical axis of the lens, and the triple cemented lens group a2 corrects spherical aberration of the lens; the second doublet lens group a3 is mainly used for correcting residual coma and curvature of field of the system diaphragm. By adopting two double-cemented lens group and one triple-cemented lens group, the machining precision can be reduced on the premise of ensuring effective chromatic aberration correction, and the manufacturability design is improved.
An aperture stop d is further arranged between the sixth lens 16 and the seventh lens 17, which can limit the light flux of the projection lens, and can shield the light rays with large aberration at the edge position according to the F number of the projection lens.
As shown in fig. 1, the middle lens group 102 includes a tenth lens element 110; the tenth lens 110 is a spherical lens. The tenth lens 110 is positive in diopter. The middle group lens 102 can move relative to the front group lens 103 and the rear group lens 101 along the direction of the optical axis, so that focusing imaging with different projection sizes can be realized.
The front group lens 103 includes an eleventh lens 111, a twelfth lens 112, and a thirteenth lens 113 arranged in this order in a direction gradually approaching the reflection system 10 b. The eleventh lens 111 and the twelfth lens 112 are spherical lenses, and the thirteenth lens 113 is an aspherical lens. The refractive power of the eleventh lens 11 is positive, the refractive power of the twelfth lens 12 is negative, and the refractive power of the thirteenth lens 13 is negative.
In the embodiment of the present invention, the aspheric lens is disposed at a position close to the reflection system 10b, the reflection system 10b compresses the light beam in a large proportion, and the thirteenth lens 113 close to the reflection system 10b is disposed as an aspheric lens, so that astigmatism can be effectively improved and distortion can be effectively corrected.
In practical applications, the thirteenth lens 113 may be an aspheric meniscus lens, and a plastic aspheric lens, and the caliber of the aspheric lens near the reflective system 10b is larger, so the thirteenth lens 113 may be made of plastic material for improving manufacturability and reducing cost.
The reflecting mirror in the reflecting system is a concave reflecting mirror and is used for compressing the angle of light rays, and particularly can be a concave-convex double-aspheric surface reflecting mirror or a double-free-form surface reflecting mirror. In the embodiment of the present invention, the reflection system 10b participates in imaging, and effectively performs light compression to realize large-size image display. Distortion is inevitably generated when light is compressed in a large proportion, and therefore astigmatism and distortion can be effectively corrected by using an aspherical mirror or a free-form surface mirror.
According to the embodiment of the invention, the aspheric lens and the aspheric reflector or the free-form surface reflector are adopted to correct the aberration of the large field of view, so that the resolving power of the lens is improved, and the imaging quality with high resolution is realized.
According to the embodiment of the invention, the second surface s2 of the reflector is adopted to reflect the imaging light, and the concave-convex double-aspheric reflector or the double-free-form surface reflector also participates in the process of chromatic aberration correction, so that the degree of freedom and the capability of chromatic aberration correction of the projection lens are increased.
In the embodiment of the present invention, the equivalent focal length of the projection lens, the equivalent focal length of the rear group lens, the equivalent focal length of the middle group lens, the equivalent focal length of the front group lens, and the equivalent focal length of the reflection system satisfy the following relations:
5<|FB/F|<12；
15<|FM/F|<25；
10<|FF/F|<20；
3<|FC/F|<12；
where F denotes an equivalent focal length of the projection lens, FB denotes an equivalent focal length of the rear group lens 101, FM denotes an equivalent focal length of the middle group lens 102, FF denotes an equivalent focal length of the front group lens 103, and FC denotes an equivalent focal length of the reflection system 10 b.
The refractive system 10a and the reflective system 10b in the projection lens generate positive diopter for converging light. The projection lens adopts a secondary imaging structure, modulated light emitted by the light valve modulation component is subjected to primary imaging between the refraction system 10a and the reflection system 10b after passing through the refraction system 10a, and secondary undistorted imaging is formed on a projection screen after the primary imaging is reflected by the reflection system 10 b.
The projection lens provided by the embodiment of the invention has a compact overall architecture, and the large-field aberration is corrected by arranging the aperture diaphragm d, the aspheric lens and the aspheric reflector or the free-form surface reflector, so that the resolving power of the projection lens is improved, and high-quality image display can be realized in the spectral range of 450 nm-645 nm.
The projection ratio of the projection lens adopting the telecentric architecture is 0.2-0.25, the use requirement of the ultra-short-focus projection lens is met, the distance between the projection equipment and the projection screen is greatly shortened, and the image display of 70-100 inches can be realized while the projection distance is shortened.
The lengths of the refractive system 10a and the reflective system 10b satisfy the following relationship:
1.5<L1/L2<2；
the rear working distance of the projection lens meets the following relation:
0.35<BFL/L2<0.7；
where L1 denotes the total length of the refractive system 10a, L2 denotes the distance between the refractive system 10a and the reflective system 10b, and BFL denotes the rear working distance of the projection lens.
By adopting the optical system with the structural design provided by the embodiment of the invention, the rear working distance can be increased on the premise of ensuring that the overall size of the projection lens is within an acceptable range, so that elements such as a beam splitter prism, an image shift mirror group and the like can be added, and the display resolution is improved.
The embodiment of the invention also performs optical simulation on the projection lens, wherein the F number of the projection lens is 2.0, the Effective Focal Length (FFL) is 2.195mm, the offset of the image plane relative to the optical axis (the ratio of the distance between the center of the emergent light of the light valve modulation component and the optical axis to the half height of the emergent light beam of the light valve modulation component) is 140% -150%, the resolving power can reach 93lp/mm, the size of a projected picture can be 70-100 inches, and the projection ratio (projection distance/picture Length) is 0.20-0.25.
Fig. 2 is a lateral chromatic aberration curve diagram of a projection lens according to an embodiment of the present invention, in which an abscissa represents a lateral chromatic aberration, which may also be referred to as a vertical axis chromatic aberration; the ordinate represents the field of view or object height.
As shown in FIG. 2, two symmetrical curves respectively located at two sides of the longitudinal axis represent the positions of the Airy spots, and the four curves respectively represent the vertical axis chromatic aberration generated by the wavelengths of 450nm, 525nm, 620nm and 645 nm. As can be seen from fig. 2, the color difference of the red, green and blue bands is less than or equal to 0.3 pixels. Based on the design of the projection lens provided by the embodiment of the invention, the chromatic aberration generated by different primary colors can be effectively improved, and the spectrum is expanded to 450 nm-645 nm.
Fig. 3 is a fan-plane view of light provided by an embodiment of the present invention. In which aberration values between the wavelengths 450nm, 525nm, 620nm, 645nm and the dominant wavelength light at the respective normalized field conditions on the horizontal axis and the vertical axis, respectively, are shown.
As shown in fig. 3, 10 fields of view each representing normalization are shown; the two graphs in each field of view are respectively a transverse axis and a longitudinal axis which are symmetrical in the meridian direction and the sagittal direction by taking the optical axis as the center; the horizontal axis direction in each graph is the pupil height position under the condition of the field of view, and the vertical axis direction is the error between the respective wavelength ray and the principal ray. Wherein the maximum ruler in FIG. 3 is. + -. 15 μm.
As can be seen from fig. 3, the coincidence degree of the curves with different wavelengths in each field of view is high, and the maximum value of the longitudinal axis is also within an acceptable range.
In another aspect of the embodiment of the present invention, a projection system is provided, and fig. 4 is a schematic structural diagram of the projection system provided in the embodiment of the present invention.
As shown in fig. 4, the projection system includes: a projection light source 200, a beam splitter 300, a light valve modulation unit 400, an image shift mirror 500, and any of the projection lenses 100.
In the embodiment of the present invention, the projection light source 200 may adopt a laser light source, and the laser light source may adopt a monochromatic laser, a laser capable of emitting laser light of multiple colors, or multiple lasers emitting laser light of different colors. When the laser light source adopts a monochromatic laser, the laser display device also needs to be provided with a color wheel, the color wheel is used for carrying out color conversion, and the monochromatic laser can be matched with the color wheel to emit primary color light with different colors according to time sequence. When the laser light source adopts a laser capable of emitting lasers with various colors, the laser light source needs to be controlled to emit lasers with different colors as primary color light according to a time sequence.
The beam splitter prism 300 is positioned between the light valve modulation part 400 and the projection lens 100; the light valve modulation part 400 is located on the reflection path of the beam splitter prism 300; the projection light source 200 is located at the light incident side of the beam splitter prism 300.
The light emitted from the projection light source 200 passes through the light uniformizing part and the illumination light path and then irradiates onto the beam splitter prism 300 in a proper size, the beam splitter prism 300 reflects the light of the light source onto the light valve modulating part 400, the light valve modulating part 400 modulates the incident light and then reflects the modulated light to the beam splitter prism 300 again, and the modulated light passes through the beam splitter prism 300 and then enters the projection lens 100. In a specific implementation, the beam splitting prism may adopt a TIR prism or an RTIR prism, which is not limited herein.
The light valve modulating unit 400 is used to modulate and reflect the incident light. In specific implementation, the light valve modulating component 400 may employ a Digital micro mirror Device (DMD), the DMD is a reflective light valve Device, the surface of the DMD includes thousands of micro mirrors, and each micro mirror is used as a pixel for reflecting red light, green light, and blue light in a time-sharing manner, so that the three primary lights are fused into a color pixel at the same position.
The image shift group 500 is located between the beam splitter 300 and the projection lens 100, and the image shift group 500 is used for shifting the emergent light. In specific implementation, the image shift mirror group 500 may be made of flat glass, and the plane where the image shift mirror group 500 is located may generate angle change, and when the image shift mirror group 500 generates vibration at a higher frequency between different placement angles, the DMD emergent light may be projected to different positions of the projection lens, so as to realize the shift of the image.
The projection lens provided by the embodiment of the invention can realize the display of a chromatic aberration correction image with high resolution of 4K by matching with the DMD and the image shift lens group, and the diffraction limit of chromatic aberration correction reaches within 0.3 pixel.
Fig. 5 is a schematic projection diagram of a projection system according to an embodiment of the present invention.
As shown in fig. 5, the projection system may further include a projection screen 600, and the projection screen 600 may be a curtain assembled with the projection system, or may be a wall surface, which is not limited herein. As can be seen from fig. 5, the final image after being imaged by the projection lens 100 is projected onto the projection screen 600, and the distance between the rear surface of the projection system and the projection screen 600 is much smaller than the size of the projection image, thereby realizing ultra-short-focus projection display. The projection system provided by the embodiment of the invention has the projection ratio of 0.20-0.25.
While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such 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 such modifications and variations.
Claims (11)
1. A projection lens, comprising:
the refraction system is used for imaging the incident image light;
the reflection system is positioned at the light emergent end of the refraction system and is used for imaging the imaging light of the refraction system again and reflecting the imaging light to a set position;
wherein the refraction system comprises:
the front lens group is positioned at one side close to the reflecting system;
the middle lens group is positioned on one side of the front lens group, which is far away from the reflecting system;
the rear lens group is positioned on one side of the middle lens group, which is far away from the front lens group; the rear lens group comprises two double-cemented lens groups and a triple-cemented lens group;
the reflecting system comprises a reflecting mirror, the reflecting mirror comprises a first surface close to the front lens group and a second surface departing from the front lens group, and the second surface is used for reflecting the imaging light of the refracting system.
2. The projection lens of claim 1 wherein the rear lens group comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, an aperture stop, a seventh lens, an eighth lens and a ninth lens arranged in this order along a direction gradually approaching the reflection system;
the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens and the ninth lens are all spherical lenses.
3. The projection lens of claim 2, wherein the diopter of the first lens is positive, the diopter of the second lens is positive, the diopter of the third lens is negative, the diopter of the fourth lens is positive, the diopter of the fifth lens is negative, the diopter of the sixth lens is positive, the diopter of the seventh lens is positive, the diopter of the eighth lens is positive, and the diopter of the ninth lens is negative;
wherein the second lens and the third lens are cemented to each other; the abbe number of the second lens is larger than that of the third lens; the refractive index of the second lens is smaller than that of the third lens;
the fourth lens, the fifth lens and the sixth lens are cemented with each other; the abbe number of the fourth lens is larger than that of the fifth lens, and the abbe number of the fifth lens is smaller than that of the sixth lens; the refractive index of the fourth lens is smaller than that of the fifth lens, and the refractive index of the fifth lens is larger than that of the sixth lens;
the eighth lens and the ninth lens are cemented with each other; the abbe number of the eighth lens is smaller than that of the ninth lens; the refractive index of the eighth lens is greater than the refractive index of the ninth lens.
4. The projection lens of claim 1 wherein the middle lens group comprises a tenth lens; the tenth lens is a spherical lens.
5. The projection lens of claim 4 wherein the tenth lens is positive in diopter.
6. The projection lens of claim 1 wherein the front lens group comprises an eleventh lens, a twelfth lens and a thirteenth lens arranged in sequence along a direction gradually approaching the reflection system;
the eleventh lens and the twelfth lens are spherical lenses, and the thirteenth lens is an aspherical lens.
7. The projection lens of claim 6, wherein the refractive power of the eleventh lens is positive, the refractive power of the twelfth lens is negative, and the refractive power of the thirteenth lens is negative.
8. The projection lens of claim 1 wherein the mirror is a bi-aspheric mirror or a bi-freeform mirror.
9. The projection lens as claimed in any one of claims 1 to 8, wherein the equivalent focal length of the projection lens, the equivalent focal length of the rear group lens, the equivalent focal length of the middle group lens, the equivalent focal length of the front group lens and the equivalent focal length of the reflection system satisfy the following relationships:
5＜|FB/F|＜12；
15＜|FM/F|＜25；
10＜|FF/F|＜20；
3＜|FC/F|＜12；
wherein F represents an equivalent focal length of the projection lens, FB represents an equivalent focal length of the rear lens group, FM represents an equivalent focal length of the middle lens group, FF represents an equivalent focal length of the front lens group, and FC represents an equivalent focal length of the reflection system.
10. The projection lens of any of claims 1-8 wherein the projection lens has a throw ratio of 0.2 to 0.25;
the lengths of the refractive system and the reflective system satisfy the following relationship:
1.5＜L1/L2＜2；
the rear working distance of the projection lens meets the following relation:
0.35＜BFL/L2＜0.7；
wherein L1 denotes an overall length of the refractive system, L2 denotes a distance between the refractive system and the reflective system, and BFL denotes a rear working distance of the projection lens.
11. A projection system, comprising a projection light source, a beam splitter prism, a light valve modulation unit, an image shift mirror group and the projection lens of any one of claims 1 to 10;
the projection light source is used for emitting light with different colors according to time sequence;
the beam splitting prism is positioned between the light valve modulation component and the projection lens; the beam splitter prism is used for reflecting the emergent light of the projection light source to the light valve modulation component and transmitting the emergent light of the light valve modulation component;
the light valve modulation component is positioned on a reflection path of the beam splitter prism; the light valve modulation component is used for modulating and reflecting incident light;
the image shift mirror group is positioned between the beam splitter prism and the projection lens and is used for shifting emergent rays.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111631763.2A CN114296217A (en) | 2021-12-29 | 2021-12-29 | Projection lens and projection system |
| PCT/CN2022/136613 WO2023124807A1 (en) | 2021-12-29 | 2022-12-05 | Projection device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111631763.2A CN114296217A (en) | 2021-12-29 | 2021-12-29 | Projection lens and projection system |
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| Publication Number | Publication Date |
|---|---|
| CN114296217A true CN114296217A (en) | 2022-04-08 |
Family
ID=80970802
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111631763.2A Withdrawn CN114296217A (en) | 2021-12-29 | 2021-12-29 | Projection lens and projection system |
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| Country | Link |
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| CN (1) | CN114296217A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114859524A (en) * | 2022-07-07 | 2022-08-05 | 沂普光电(天津)有限公司 | Ultra-short-focus optical system and projection equipment |
| CN115793361A (en) * | 2023-02-01 | 2023-03-14 | 沂普光电(天津)有限公司 | Ultra-short-focus projection lens and system |
| CN116088254A (en) * | 2023-04-10 | 2023-05-09 | 沂普光电(天津)有限公司 | Low-projection-ratio optical system |
| WO2023124807A1 (en) * | 2021-12-29 | 2023-07-06 | 青岛海信激光显示股份有限公司 | Projection device |
| WO2023124812A1 (en) * | 2021-12-31 | 2023-07-06 | 青岛海信激光显示股份有限公司 | Projection device |
-
2021
- 2021-12-29 CN CN202111631763.2A patent/CN114296217A/en not_active Withdrawn
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2023124807A1 (en) * | 2021-12-29 | 2023-07-06 | 青岛海信激光显示股份有限公司 | Projection device |
| WO2023124812A1 (en) * | 2021-12-31 | 2023-07-06 | 青岛海信激光显示股份有限公司 | Projection device |
| CN114859524A (en) * | 2022-07-07 | 2022-08-05 | 沂普光电(天津)有限公司 | Ultra-short-focus optical system and projection equipment |
| CN114859524B (en) * | 2022-07-07 | 2022-10-25 | 沂普光电(天津)有限公司 | Ultra-short-focus optical system and projection equipment |
| WO2024007740A1 (en) * | 2022-07-07 | 2024-01-11 | 沂普光电(天津)有限公司 | Ultra-short throw optical system and projection apparatus |
| CN115793361A (en) * | 2023-02-01 | 2023-03-14 | 沂普光电(天津)有限公司 | Ultra-short-focus projection lens and system |
| CN115793361B (en) * | 2023-02-01 | 2023-05-16 | 沂普光电(天津)有限公司 | Ultra-short-focus projection lens and system |
| CN116088254A (en) * | 2023-04-10 | 2023-05-09 | 沂普光电(天津)有限公司 | Low-projection-ratio optical system |
| CN116088254B (en) * | 2023-04-10 | 2023-08-08 | 沂普光电(天津)有限公司 | Low-projection-ratio optical system |
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Application publication date: 20220408 |