CN107817593B - Ultra-short focal projection lens - Google Patents
Ultra-short focal projection lens Download PDFInfo
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- CN107817593B CN107817593B CN201711248477.1A CN201711248477A CN107817593B CN 107817593 B CN107817593 B CN 107817593B CN 201711248477 A CN201711248477 A CN 201711248477A CN 107817593 B CN107817593 B CN 107817593B
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- 230000003287 optical effect Effects 0.000 claims description 35
- 238000005286 illumination Methods 0.000 claims description 33
- 239000011521 glass Substances 0.000 claims description 3
- 230000009286 beneficial effect Effects 0.000 abstract description 5
- 238000004519 manufacturing process Methods 0.000 abstract description 5
- 238000003384 imaging method Methods 0.000 description 29
- 238000010586 diagram Methods 0.000 description 11
- 210000001747 pupil Anatomy 0.000 description 3
- 206010010071 Coma Diseases 0.000 description 2
- 201000009310 astigmatism Diseases 0.000 description 2
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- 238000012634 optical imaging Methods 0.000 description 2
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- 238000005452 bending Methods 0.000 description 1
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- 239000003292 glue Substances 0.000 description 1
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/001—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras
- G02B13/0015—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design
- G02B13/005—Miniaturised objectives for electronic devices, e.g. portable telephones, webcams, PDAs, small digital cameras characterised by the lens design having spherical lenses only
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B21/00—Projectors or projection-type viewers; Accessories therefor
- G03B21/005—Projectors using an electronic spatial light modulator but not peculiar thereto
- G03B21/008—Projectors using an electronic spatial light modulator but not peculiar thereto using micromirror devices
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B21/00—Projectors or projection-type viewers; Accessories therefor
- G03B21/14—Details
- G03B21/28—Reflectors in projection beam
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Abstract
The invention discloses an ultra-short focal projection lens. The ultra-short focal projection lens includes: the display chip is used for displaying an object plane to be projected; the refraction lens group is arranged on the light emitting side of the display chip, and comprises a plurality of lenses, wherein each lens is a spherical lens and is used for balancing aberration formed by the projection object plane light passing through the refraction lens group; and the reflecting mirror is positioned at one side of the refraction lens group, which is away from the display chip, and is used for reducing field curvature and distortion caused by the refraction lens group and reflecting light rays to form an enlarged projection image surface. According to the technical scheme, the spherical lenses are matched, so that aberration formed by the projection object plane light passing through the refraction lens group is balanced; the field curvature and distortion are reduced through the reflector, and the light is reflected to form an enlarged projection image surface, so that a large image is projected in a short distance and high quality. And the refractive lens group is all spherical lenses, and the lens group does not contain aspheric lenses and double-cemented lenses, thereby being beneficial to processing and mass production.
Description
Technical Field
The embodiment of the invention relates to the technology of projection optical systems, in particular to an ultra-short focal projection lens.
Background
In recent years, ultra-short-focus projection lenses have been attracting more and more attention in the short-focus projection market. On one hand, compared with the common projection lens, the ultra-short-focus projection lens greatly shortens the projection distance, can project a picture with a large view field in a very short projection distance, improves the space utilization rate, and can also avoid shielding of shadows or other objects; on the other hand, the design of the ultra-short focal projection lens has high requirements for optimization of resolution, light intensity, various aberrations, and the like.
The lenses of ultra-short focus projectors currently on the market include three ways: reflective, refractive, hybrid. Since the main element of projection lens imaging is a refractive lens, various aberrations are generated by the refractive lens during imaging. In order to correct the aberration, the existing design generally includes at least one aspheric lens and two cemented lenses, which results in the problems of complex processing and assembly, unstable precision, and the like, and the cemented lens may cause local melting of the glue at high temperature, which affects the projection effect.
Disclosure of Invention
The invention provides an ultra-short focal projection lens, which is used for achieving the purpose of projecting a large image in a short distance and high quality.
The embodiment of the invention provides an ultra-short focal projection lens, which comprises:
the display chip is used for displaying an object plane to be projected;
The refraction lens group is arranged on the light emitting side of the display chip and comprises a plurality of lenses, and each lens is a spherical lens and is used for balancing aberration formed by the projection object plane light passing through the refraction lens group;
And the reflecting mirror is positioned at one side of the refraction lens group, which is away from the display chip, and is used for reducing field curvature and distortion caused by the refraction lens group and reflecting light rays to form an enlarged projection image surface.
Optionally, the device also comprises a refraction prism and an illumination light source; the refraction prism is positioned between the display chip and the refraction lens group and comprises a first light incident surface, a second light incident surface and a light emergent surface, and the first light incident surface is crossed with the second light incident surface and the light emergent surface; the light emitting surface of the illumination light source is opposite to the first light entering surface of the refraction prism, the light emitting side of the display chip is opposite to the second light entering surface of the refraction prism, the light entering surface of the refraction lens group is opposite to the light emitting surface of the refraction prism, and the refraction prism is used for refracting illumination light beams emitted by the illumination light source to the display chip.
Optionally, the display chip is a digital micromirror device DMD.
Optionally, the refractive lens group includes fifteen spherical lenses, and the fifteen spherical lenses are coaxially arranged, and include a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens, a tenth lens, an eleventh lens, a twelfth lens, a thirteenth lens, a fourteenth lens, and a fifteenth lens that are sequentially arranged along the optical path;
The first lens is a positive meniscus lens, the second lens is a positive meniscus lens, the third lens is a positive meniscus lens, the fourth lens is a negative meniscus lens, the fifth lens is a biconvex lens, the sixth lens is a negative meniscus lens, the seventh lens is a biconvex lens, the eighth lens is a negative meniscus lens, the ninth lens is a positive meniscus lens, the tenth lens is a positive meniscus lens, the eleventh lens is a negative meniscus lens, the twelfth lens is a positive meniscus lens, the thirteenth lens is a biconcave lens, the fourteenth lens is a positive meniscus lens, and the fifteenth lens is a negative meniscus lens.
Optionally, the lens system further comprises an aperture stop, wherein the aperture stop is arranged between the fourth lens and the fifth lens and is used for controlling the depth of field, the range of an imaging object space and the brightness of an image.
Optionally, the refractive lens group includes fifteen spherical lenses, and the fifteen spherical lenses are coaxially arranged, and include a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens, a tenth lens, an eleventh lens, a twelfth lens, a thirteenth lens, a fourteenth lens, and a fifteenth lens that are sequentially arranged along the optical path;
the first lens is a biconvex lens, the second lens is a biconvex lens, the third lens is a plano-convex lens, the fourth lens is a biconcave lens, the fifth lens is a plano-convex lens, the sixth lens is a biconvex lens, the seventh lens is a biconcave lens, the eighth lens is a biconvex lens, the ninth lens is a biconcave lens, the tenth lens is a biconvex lens, the eleventh lens is a negative meniscus lens, the twelfth lens is a positive meniscus lens, the thirteenth lens is a biconvex lens, the fourteenth lens is a positive meniscus lens, and the fifteenth lens is a biconcave lens.
Optionally, the lens system further comprises an aperture stop, wherein the aperture stop is arranged between the fifth lens and the sixth lens and is used for controlling the depth of field, the range of the imaging object space and the brightness of an image.
Optionally, the reflecting mirror is an aspherical reflecting mirror.
Optionally, the aspheric reflecting mirror is concave, and the surface shape thereof is represented by the formula:
And determining, wherein z is sagittal height, c is curvature at the vertex of the curved surface, r is the distance between the projection of the coordinates of the curved surface point on the plane perpendicular to the optical axis and the optical axis, k is a conical coefficient, and a 1、a2、a3、a4、a5、a6、a7 and a 8 represent coefficients corresponding to even terms.
Optionally, the refractive lens group and the reflecting mirror have the same main optical axis.
The embodiment of the invention provides an ultra-short focal projection lens, which comprises a display chip, a refraction lens group arranged on the light emitting side of the display chip and a reflector positioned on the side, away from the display chip, of the refraction lens group; displaying an object plane to be projected through a display chip, wherein light rays of the object plane to be projected are incident to a refraction lens group; the refraction lens group is formed by matching a plurality of spherical lenses, positive aberration and negative aberration can be caused when light passes through different spherical lenses, and the aberration formed by the light of the projection object plane passing through the refraction lens group can be balanced through the matching action of the spherical lenses; the light rays emitted by the refraction lens group also have field curvature and distortion, and the reflecting mirror is used for reducing the field curvature and distortion and reflecting the light rays to form an enlarged projection image plane so as to realize short-distance and high-quality projection of large images. According to the technical scheme, all the refraction lens groups adopt spherical lenses, and the refraction lens groups do not contain aspherical lenses and double cemented lenses, so that the refraction lens groups are beneficial to processing and mass production.
Drawings
Fig. 1 is a schematic diagram of an ultrashort-focal projection lens according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of an ultrashort focal projection lens according to a second embodiment of the present invention;
Fig. 3 is a schematic view of an imaging optical path of an ultrashort focal projection lens according to a second embodiment of the present invention;
FIG. 4 is a schematic diagram of a modulation transfer function MTF curve of each field of view of a display screen according to a second embodiment of the present invention;
Fig. 5 is a schematic structural diagram of an ultrashort focal projection lens according to a third embodiment of the present invention;
fig. 6 is a schematic diagram of an imaging optical path of an ultrashort focal projection lens according to a third embodiment of the present invention;
fig. 7 is a schematic diagram of a modulation transfer function MTF curve of each field of view of a display screen according to the third embodiment of the present invention.
Detailed Description
The invention is described in further detail below with reference to the drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting thereof. It should be further noted that, for convenience of description, only some, but not all, of the structures related to the present invention are shown in the drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The description of the embodiments is made for the sake of understanding only, and is not intended to be limiting of the specific orientations.
Example 1
Fig. 1 is a schematic structural diagram of an ultrashort-focal projection lens according to an embodiment of the present invention. The ultra-short focal projection lens includes: a display chip 100 for displaying an object plane to be projected; the refraction lens group 200 is arranged on the light emitting side of the display chip 100, and the refraction lens group 200 comprises a plurality of lenses, wherein each lens is a spherical lens and is used for balancing aberration formed by the projection object plane light passing through the refraction lens group 200; the reflecting mirror 300 is located at a side of the refractive lens assembly 200 away from the display chip 100, and is used for reducing curvature of field and distortion caused by the refractive lens assembly 200, and reflecting light to form an enlarged projection image plane.
It is understood that aberration is a phenomenon of ideal imaging of off-paraxial rays due to off-paraxial rays in an actual optical system, and mainly includes spherical aberration, coma, chromatic aberration, astigmatism, curvature of field, distortion, and the like. For example, a positive lens converges light beams, and generates negative spherical aberration, a negative lens diverges light beams, and generates positive spherical aberration, so that spherical aberration, coma, chromatic aberration, astigmatism, etc. can be effectively balanced by using a plurality of spherical lenses to cooperate with each other, but uncorrected curvature of field and distortion are left. The light rays are incident to the reflecting mirror 300 after passing through the refraction lens group 200, the optical path of the reflecting mirror 300 can be increased, the volume of the projection lens is reduced, the surface of the reflecting mirror 300 is calculated and fitted, the field curvature and distortion are reduced, and the light rays are emitted, for example, imaged on a receiving screen, so that a clear and enlarged projection image surface is achieved.
The embodiment of the invention provides an ultra-short focal projection lens, which comprises a display chip, a refraction lens group arranged on the light emitting side of the display chip and a reflector positioned on the side, away from the display chip, of the refraction lens group; displaying an object plane to be projected through a display chip, wherein light rays of the object plane to be projected are incident to a refraction lens group; the refraction lens group is formed by matching a plurality of spherical lenses, positive aberration and negative aberration can be caused when light passes through different spherical lenses, and the aberration formed by the light of the projection object plane passing through the refraction lens group can be balanced through the matching action of the spherical lenses; the light rays emitted by the refraction lens group also have field curvature and distortion, and the reflecting mirror is used for reducing the field curvature and distortion and reflecting the light rays to form an enlarged projection image plane so as to realize short-distance and high-quality projection of large images. According to the technical scheme, all the refraction lens groups adopt spherical lenses, and the refraction lens groups do not contain aspherical lenses and double cemented lenses, so that the refraction lens groups are beneficial to processing and mass production.
Optionally, the ultra-short focal projection system provided by the embodiment of the present invention further includes a refractive prism 400 and an illumination light source 500; the refractive prism 400 is located between the display chip 100 and the refractive lens group 200, and the refractive prism includes a first light incident surface, a second light incident surface and a light emergent surface, where the first light incident surface and the second light incident surface are all intersected; the light emitting surface of the illumination light source 500 is opposite to the first light incident surface of the refraction prism 400, the light emitting side of the display chip 100 is opposite to the second light incident surface of the refraction prism 400, the light incident surface of the refraction lens group 200 is opposite to the light emitting surface of the refraction prism 400, and the refraction prism 400 is used for refracting the illumination light beam emitted by the illumination light source 500 to the display chip 100.
It can be understood that, taking fig. 1 as an example, the illumination beam emitted by the illumination light source 500 enters the refractive prism 400 from the first light incident surface (the upper surface of the refractive prism 400 in the view of fig. 1), passes through the refractive surface inside the refractive prism 400, exits onto the display chip 100 through the second light incident surface (the left surface of the refractive prism 400 in the view of fig. 1), forms an object plane to be projected by modulating the illumination beam, enters the refractive prism 400 from the second light incident surface, and enters the refractive lens group 200 after passing through the light emergent surface (the right surface of the refractive prism 400 in the view of fig. 1) of the refractive prism 400.
Alternatively, the display chip 100 is a Digital Micro-mirror Device (DMD).
And the digital micro-mirror device is used for modulating the illumination beam to display the micro-image and is used as an object plane of the projection lens. For example, a 4096 x 2160 resolution digital micromirror device is possible to meet the requirements of high quality imaging.
Alternatively, the mirror 300 is an aspherical mirror. The aspherical mirror is concave, and its surface shape is represented by the formula:
And determining, wherein z is sagittal height, c is curvature at the vertex of the curved surface, r is the distance between the projection of the coordinates of the curved surface point on the plane perpendicular to the optical axis and the optical axis, k is a conical coefficient, and a 1、a2、a3、a4、a5、a6、a7 and a 8 represent coefficients corresponding to even terms.
The curved surface shape of the reflecting mirror 300 designed by the above formula can effectively reduce the field curvature and distortion remained after the light passes through the refractive lens group 200, so that the imaging keeps high brightness and no deformation, and a high-quality projection large image is generated.
Alternatively, refractive lens group 200 has the same principal optical axis as mirror 300.
By the coaxial arrangement of the refractive lens group 200 and the reflecting mirror 300, the complexity of lens design is reduced, and the projection accuracy can be improved. The display chip 100 of the whole lens and the refraction lens group 200 formed by a plurality of lenses, the reflecting mirror 300 are all on the same main optical axis, light rays are paraxial light rays, the pupil matching principle of an illumination system and an imaging system is met, the use of a prism system is reduced, and the distance and the relative position of each lens in the lens are subjected to calculation and balance aberration.
Example two
Fig. 2 is a schematic structural diagram of an ultra-short focal projection lens according to a second embodiment of the present invention, which is a specific example based on the first embodiment, referring to fig. 2, the ultra-short focal projection lens provided in the present embodiment includes a display chip 100, a refractive lens group 200 and a reflecting mirror 300, wherein the display chip 100 may be a 0.65 inch digital micromirror device with a resolution of 4096×2160 for providing a high-definition projection surface; the refractive lens group 200 includes fifteen spherical lenses coaxially arranged, including a first lens 201, a second lens 202, a third lens 203, a fourth lens 204, a fifth lens 205, a sixth lens 206, a seventh lens 207, an eighth lens 208, a ninth lens 209, a tenth lens 210, an eleventh lens 211, a twelfth lens 212, a thirteenth lens 213, a fourteenth lens 214, and a fifteenth lens 215, which are sequentially arranged along the optical path; the first lens 201 is a positive meniscus lens, the second lens 202 is a positive meniscus lens, the third lens 203 is a positive meniscus lens, the fourth lens 204 is a negative meniscus lens, the fifth lens 205 is a biconvex lens, the sixth lens 206 is a negative meniscus lens, the seventh lens 207 is a biconvex lens, the eighth lens 208 is a negative meniscus lens, the ninth lens 209 is a positive meniscus lens, the tenth lens 210 is a positive meniscus lens, the eleventh lens 211 is a negative meniscus lens, the twelfth lens 212 is a positive meniscus lens, the thirteenth lens 213 is a biconcave lens, the fourteenth lens 214 is a positive meniscus lens, and the fifteenth lens 215 is a negative meniscus lens.
Wherein, optionally, the materials of the fifteen spherical lenses of the refraction lens group 200 are all environment-friendly glass, and optionally, the specific parameters of the fifteen spherical lenses are shown in table 1, the size and the distance of each spherical lens are designed by an optical imaging principle, and the components are calculated and optimized by a computer, so that the manufacturability of the components is good and the environment can be protected. Wherein the surfaces of the lenses are numbered along the direction of light propagation, resulting in a surface number for each surface of the lenses, e.g. surface 1 and surface 2 represent the first and second surfaces of the first lens 201, respectively, and so on. It will be appreciated that the radius of the surface 1 is infinitely variable, meaning that the surface 1 is planar.
Table 1 spherical lens parameter table
Optionally, the ultra-short focal projection lens of the present embodiment further includes an aperture stop (not shown in fig. 2), which is disposed between the fourth lens 204 and the fifth lens 205, for controlling the depth of field, the range of the imaging object space, and the brightness of the image.
After passing through the fourth lens 204, the light rays can be converged to form an intermediate image, and the imaging quality of the outer point of the optical axis can be improved, the depth of field can be controlled, the imaging quality can be improved, and the definition of the image can be improved through the arrangement of the aperture diaphragm. After passing through the fifteenth lens 215, the second intermediate image is formed, and the second intermediate image is reflected by the reflecting mirror 300 to obtain an enlarged projection picture.
After the light enters the fifth lens 205, the light is refracted by the fifth lens 205 and the sixth lens 206, so that the spherical aberration and chromatic aberration are effectively reduced, and the generation of halation is reduced. The modulation of the seventh lens 207 to the fifteenth lens 215 balances the above-mentioned other aberrations, increases the optical path by reflection of the mirror 300, and forms a large and clear image without bending after changing the light-emitting angle, thereby improving the imaging quality.
Optionally, the ultra-short focal projection system provided in this embodiment further includes a refractive prism 400 and an illumination light source 500; the refractive prism 400 is located between the display chip 100 and the refractive lens group 200, and the refractive prism includes a first light incident surface, a second light incident surface and a light emergent surface, where the first light incident surface and the second light incident surface are all intersected; the light emitting surface of the illumination light source 500 is opposite to the first light incident surface of the refraction prism 400, the light emitting side of the display chip 100 is opposite to the second light incident surface of the refraction prism 400, the light incident surface of the refraction lens group 200 is opposite to the light emitting surface of the refraction prism 400, and the refraction prism 400 is used for refracting the illumination light beam emitted by the illumination light source 500 to the display chip 100.
It can be understood that, taking fig. 2 as an example, the illumination beam emitted by the illumination light source 500 enters the refractive prism 400 from the first light incident surface (the upper surface of the refractive prism 400 in the view of fig. 2), passes through the refractive surface inside the refractive prism 400, exits onto the display chip 100 through the second light incident surface (the left surface of the refractive prism 400 in the view of fig. 2), forms an object plane to be projected by modulating the illumination beam, enters the refractive prism 400 from the second light incident surface, and enters the refractive lens group 200 after passing through the light emergent surface (the right surface of the refractive prism 400 in the view of fig. 2) of the refractive prism 400.
Alternatively, the mirror 300 is an aspherical mirror. The aspherical mirror is concave, and its surface shape is represented by the formula:
And determining, wherein z is sagittal height, c is curvature at the vertex of the curved surface, r is the distance between the projection of the coordinates of the curved surface point on the plane perpendicular to the optical axis and the optical axis, k is a conical coefficient, a 1、a2、a3、a4、a5、a6、a7 and a 8 represent coefficients corresponding to even terms, and specific parameters are shown in table 2.
TABLE 2 mirror surface parameters
The curved surface shape of the reflecting mirror 300 designed in the above way has more degrees of freedom, and can effectively reduce the residual curvature and distortion of the field of the light after passing through the refractive lens group 200, so that the imaging keeps high brightness and no deformation, and a high-quality projection large image is generated.
Alternatively, refractive lens group 200 has the same principal optical axis as mirror 300.
By the coaxial arrangement of the refractive lens group 200 and the reflecting mirror 300, the complexity of lens design is reduced, and the projection accuracy can be improved. The display chip 100 of the whole lens and the refraction lens group 200 formed by fifteen lenses are arranged on the same main optical axis, the light rays are paraxial light rays, the pupil matching principle of an illumination system and an imaging system is met, the use of a prism system is reduced, and the distance and the relative position of each lens in the lens are subjected to calculation and balance aberration.
When designing a projection lens, the projection ratio refers to a parameter of a ratio of a projection distance to a picture width, and the smaller the projection ratio is, the larger a picture projected from the same distance is, and the projection lens with the projection ratio smaller than 0.38 is generally defined as an ultra-short focal projection lens in the industry.
Fig. 3 is a schematic view of an imaging optical path of the ultra-short focal projection lens provided in this embodiment, where the projection ratio of the ultra-short focal projection lens provided in this embodiment is 0.21, and a field angle of 135 ° to 140 ° can be provided, and the magnification is 138 to 169, so that a high-definition display screen of 90 to 110 inches can be realized at a projection distance of 420mm to 510 mm.
Fig. 4 is a schematic diagram of an MTF curve of each field of view of a certain display screen projected by this embodiment, in this embodiment, a digital micromirror device with a resolution of 4096×2160 and a projection distance of 465mm, and a screen size of 100 inches is adopted, and since the MTF values of the human eye visual resolution at different spatial frequencies are different, the MTF is required to be greater than 0.3 in this embodiment. The abscissa of the MTF curve in fig. 4 is 0.75lp/mm (line pair/mm) and the ordinate thereof is greater than 0.45, so that high-definition quality picture imaging can be realized.
According to the technical scheme, the projection ratio of the lens is 0.21, the field angle of 135-140 degrees can be provided, the magnification is 138-169, and a high-definition display picture of 90-110 inches can be realized at a projection distance of 420-510 mm; the fifteen lenses of the refraction lens group are all spherical lenses, and the aperture diaphragm is arranged between the fourth lens and the fifth lens, so that the imaging quality of an outer point of an optical axis can be improved, the depth of field can be controlled, the imaging quality can be improved, and the definition of an image can be improved; the design does not contain an aspheric lens, and is beneficial to processing and mass production; the double-cemented lens is not contained, and the cementing damage caused by high temperature is avoided.
Example III
Fig. 5 is a schematic structural diagram of an ultra-short focal projection lens according to a third embodiment of the present invention, which is another specific example based on the first embodiment, referring to fig. 5, the ultra-short focal projection lens provided in this embodiment includes a display chip 100, a refractive lens group 200 and a reflecting mirror 300, wherein the display chip 100 may be a 0.47 inch digital micromirror device with a resolution of 4096×2160 for providing a high-definition projection surface; the refractive lens group 200 includes fifteen spherical lenses coaxially arranged, including a first lens 201, a second lens 202, a third lens 203, a fourth lens 204, a fifth lens 205, a sixth lens 206, a seventh lens 207, an eighth lens 208, a ninth lens 209, a tenth lens 210, an eleventh lens 211, a twelfth lens 212, a thirteenth lens 213, a fourteenth lens 214, and a fifteenth lens 215, which are sequentially arranged along the optical path; the first lens 201 is a biconvex lens, the second lens 202 is a biconvex lens, the third lens 203 is a plano-convex lens, the fourth lens 204 is a biconcave lens, the fifth lens 205 is a plano-convex lens, the sixth lens 206 is a biconvex lens, the seventh lens 207 is a biconcave lens, the eighth lens 208 is a biconvex lens, the ninth lens 209 is a biconcave lens, the tenth lens 210 is a biconvex lens, the eleventh lens 211 is a negative meniscus lens, the twelfth lens 212 is a positive meniscus lens, the thirteenth lens 213 is a biconvex lens, the fourteenth lens 214 is a positive meniscus lens, and the fifteenth lens 215 is a biconcave lens.
Wherein, optionally, the materials of the fifteen spherical lenses of the refraction lens group 200 are all environment-friendly glass, and optionally, the specific parameters of the fifteen spherical lenses are shown in table 3, the size and the distance of each spherical lens are designed by an optical imaging principle, and the components are calculated and optimized by a computer, so that the manufacturability of the components is good and the environment can be protected. Wherein the surfaces of the lenses are numbered along the direction of light propagation, resulting in a surface number for each surface of the lenses, e.g. surface 1 and surface 2 represent the first and second surfaces of the first lens 201, respectively, and so on.
Table 3 table of spherical lens parameters
Optionally, the ultra-short focal projection lens of the present embodiment further includes an aperture stop (not shown in fig. 5), which is disposed between the fifth lens 205 and the sixth lens 206, for controlling the depth of field, the range of the imaging object space, and the brightness of the image.
After the light passes through the fifth lens 205, the imaging quality of the outer point of the optical axis can be improved, the depth of field can be controlled, the imaging quality can be improved, and the definition of the image can be improved through the arrangement of the aperture diaphragm. After passing through the fifteenth lens 215, an intermediate image is formed by converging, and an enlarged projection image is obtained after reflecting by the reflecting mirror 300.
Optionally, the ultra-short focal projection system provided by the embodiment of the present invention further includes a refractive prism 400 and an illumination light source 500; the refractive prism 400 is located between the display chip 100 and the refractive lens group 200, and the refractive prism includes a first light incident surface, a second light incident surface and a light emergent surface, where the first light incident surface and the second light incident surface are all intersected; the light emitting surface of the illumination light source 500 is opposite to the first light incident surface of the refraction prism 400, the light emitting side of the display chip 100 is opposite to the second light incident surface of the refraction prism 400, the light incident surface of the refraction lens group 200 is opposite to the light emitting surface of the refraction prism 400, and the refraction prism 400 is used for refracting the illumination light beam emitted by the illumination light source 500 to the display chip 100.
It can be understood that, taking fig. 5 as an example, the illumination beam emitted by the illumination light source 500 enters the refractive prism 400 from the first light incident surface (the upper surface of the refractive prism 400 in the view of fig. 5), passes through the refractive surface inside the refractive prism 400, exits onto the display chip 100 through the second light incident surface (the left surface of the refractive prism 400 in the view of fig. 5), forms an object plane to be projected by modulating the illumination beam, enters the refractive prism 400 from the second light incident surface, and enters the refractive lens group 200 after passing through the light emergent surface (the right surface of the refractive prism 400 in the view of fig. 5) of the refractive prism 400.
Alternatively, the mirror 300 is an aspherical mirror. The aspherical mirror is concave, and its surface shape is represented by the formula:
And determining, wherein z is sagittal height, c is curvature at the vertex of the curved surface, r is the distance between the projection of the coordinates of the curved surface point on the plane perpendicular to the optical axis and the optical axis, k is a conical coefficient, a 1、a2、a3、a4、a5、a6、a7 and a 8 represent coefficients corresponding to even terms, and specific parameters are shown in table 4.
TABLE 4 mirror surface parameters
The curved surface shape of the reflecting mirror 300 designed in the above way has more degrees of freedom, and can effectively reduce the residual curvature and distortion of the field of the light after passing through the refractive lens group 200, so that the imaging keeps high brightness and no deformation, and a high-quality projection large image is generated.
Alternatively, refractive lens group 200 has the same principal optical axis as mirror 300.
By the coaxial arrangement of the refractive lens group 200 and the reflecting mirror 300, the complexity of lens design is reduced, and the projection accuracy can be improved. The display chip 100 of the whole lens and the refraction lens group 200 formed by fifteen lenses are arranged on the same main optical axis, the light rays are paraxial light rays, the pupil matching principle of an illumination system and an imaging system is met, the use of a prism system is reduced, and the distance and the relative position of each lens in the lens are subjected to calculation and balance aberration.
Fig. 6 is a schematic diagram of an imaging optical path principle of the ultra-short focal projection lens provided by the embodiment, where the projection ratio of the ultra-short focal projection lens provided by the embodiment is 0.21, a field angle of 135 ° to 140 ° can be provided, the magnification is 148 to 190, and a high-definition display screen of 70 to 90 inches can be realized at a projection distance of 330mm to 410 mm.
Fig. 7 is a graph of MTF of modulation transfer function of each field of view of a certain display screen projected in this embodiment, a digital micromirror device of 0.47 inches is used, the resolution is 4096×2160, the projection distance is 370mm, the screen size is 80 inches, and since the MTF values of the visual resolution of human eyes at different spatial frequencies are different, the MTF is required to be greater than 0.3 in this embodiment. The abscissa of the MTF curve in fig. 7 is greater than 0.7lp/mm (line pair/mm) and the ordinate thereof is greater than 0.5, so that high-definition quality picture imaging can be realized.
According to the technical scheme, the projection ratio of the lens is 0.21, the field angle of 135-140 degrees can be provided, the magnification is 148-190, and a high-definition display picture of 70-90 inches can be realized at a projection distance of 330-410 mm; the fifteen lenses of the refraction lens group are all spherical lenses, and an aperture diaphragm is arranged between the fifth lens and the sixth lens, so that the imaging quality of an outer point of an optical axis can be improved, the depth of field can be controlled, the imaging quality can be improved, and the definition of an image can be improved; the design does not contain an aspheric lens, and is beneficial to processing and mass production; the double-cemented lens is not contained, and the cementing damage caused by high temperature is avoided.
Note that the above is only a preferred embodiment of the present invention and the technical principle applied. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, while the invention has been described in connection with the above embodiments, the invention is not limited to the embodiments, but may be embodied in many other equivalent forms without departing from the spirit or scope of the invention, which is set forth in the following claims.
Claims (8)
1. An ultra-short focal projection lens, comprising:
the display chip is used for displaying an object plane to be projected;
The refraction lens group is arranged on the light emitting side of the display chip and comprises a plurality of lenses, and each lens is a spherical lens and is used for balancing aberration formed by the projection object plane light passing through the refraction lens group;
the reflecting mirror is positioned at one side of the refraction lens group, which is away from the display chip, and is used for reducing field curvature and distortion caused by the refraction lens group and reflecting light rays to form an enlarged projection image surface;
The refraction lens group comprises fifteen spherical lenses, wherein the fifteen spherical lenses are coaxially arranged and comprise a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens, a tenth lens, an eleventh lens, a twelfth lens, a thirteenth lens, a fourteenth lens and a fifteenth lens which are sequentially arranged along an optical path;
the first lens is a positive meniscus lens, the second lens is a positive meniscus lens, the third lens is a positive meniscus lens, the fourth lens is a negative meniscus lens, the fifth lens is a biconvex lens, the sixth lens is a negative meniscus lens, the seventh lens is a biconvex lens, the eighth lens is a negative meniscus lens, the ninth lens is a positive meniscus lens, the tenth lens is a positive meniscus lens, the eleventh lens is a negative meniscus lens, the twelfth lens is a positive meniscus lens, the thirteenth lens is a biconcave lens, the fourteenth lens is a positive meniscus lens, and the fifteenth lens is a negative meniscus lens;
or the first lens is a biconvex lens, the second lens is a biconvex lens, the third lens is a plano-convex lens, the fourth lens is a biconcave lens, the fifth lens is a plano-convex lens, the sixth lens is a biconvex lens, the seventh lens is a biconcave lens, the eighth lens is a biconvex lens, the ninth lens is a biconcave lens, the tenth lens is a biconvex lens, the eleventh lens is a negative meniscus lens, the twelfth lens is a positive meniscus lens, the thirteenth lens is a biconvex lens, the fourteenth lens is a positive meniscus lens, and the fifteenth lens is a biconcave lens;
The fifteen spherical lenses are made of environment-friendly glass.
2. The ultra-short focal projection lens of claim 1, further comprising a refractive prism and an illumination source;
the refraction prism is positioned between the display chip and the refraction lens group and comprises a first light incident surface, a second light incident surface and a light emergent surface, and the first light incident surface is crossed with the second light incident surface and the light emergent surface;
The light emitting surface of the illumination light source is opposite to the first light entering surface of the refraction prism, the light emitting side of the display chip is opposite to the second light entering surface of the refraction prism, the light entering surface of the refraction lens group is opposite to the light emitting surface of the refraction prism, and the refraction prism is used for refracting illumination light beams emitted by the illumination light source to the display chip.
3. The ultra-short focal projection lens of claim 1 wherein the display chip is a digital micromirror device DMD.
4. The ultra-short focal projection lens of claim 1, further comprising an aperture stop disposed between the fourth lens and the fifth lens for controlling a depth of field, a range of an imaged object space, and brightness of an image.
5. The ultra-short focal projection lens of claim 1, further comprising an aperture stop disposed between the fifth lens and the sixth lens for controlling a depth of field, a range of an imaged object space, and brightness of an image.
6. The ultra-short focal projection lens of claim 1 wherein the mirror is an aspherical mirror.
7. The ultra-short focal projection lens of claim 6 wherein the aspherical mirror is concave and its surface shape is represented by the formula:
And determining, wherein z is sagittal height, c is curvature at the vertex of the curved surface, r is the distance between the projection of the coordinates of the curved surface point on the plane perpendicular to the optical axis and the optical axis, k is a conical coefficient, and a 1、a2、a3、a4、a5、a6、a7 and a 8 represent coefficients corresponding to even terms.
8. The ultra-short focal projection lens of any one of claims 1-7, wherein the refractive lens group and the mirror have the same principal optical axis.
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| CN108710194B (en) * | 2018-07-17 | 2024-02-02 | 安徽仁和光电科技有限公司 | Projection lens |
| CN109884780B (en) * | 2019-04-16 | 2024-05-24 | 中山联合光电科技股份有限公司 | Ultra-short-focus projection optical system with low cost and high resolution |
| CN113835290A (en) * | 2020-06-08 | 2021-12-24 | 华为技术有限公司 | Lens assembly of projection equipment and projection equipment |
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