CN107490846B - Projection lens - Google Patents
Projection lens Download PDFInfo
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- CN107490846B CN107490846B CN201710840184.6A CN201710840184A CN107490846B CN 107490846 B CN107490846 B CN 107490846B CN 201710840184 A CN201710840184 A CN 201710840184A CN 107490846 B CN107490846 B CN 107490846B
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- lens
- projection
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- aspheric
- lens group
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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
- G02B13/18—Optical objectives specially designed for the purposes specified below with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration
-
- 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
- G03B21/142—Adjusting of projection optics
Abstract
The embodiment of the invention relates to an optical imaging technology and discloses a projection lens. The projection lens includes: a display chip for modulating the light beam from the illumination system to display the micro-image; the prism is used for totally reflecting the light rays coming out of the illuminating system to the display chip; the refraction lens group is used for balancing the aberration of the image formed by the micro image through the refraction lens group; and the reflector group is used for turning the light path and correcting the residual aberration of the image formed by the refraction lens group. According to the technical scheme of the embodiment of the invention, on the premise of reducing the projection ratio, the machining precision is ensured, and the machining cost is controlled.
Description
Technical Field
The embodiment of the invention relates to an optical imaging technology, in particular to a projection lens.
Background
With the rapid development of projection technology, the ultra-short-focus projection technology has the advantage that a large picture can be projected in a short distance, so that a small conference room has the realization possibility, and the ultra-short-focus projection technology is greatly concerned by all parties.
The initial design approach to achieve ultra-short-focus projection lenses was refractive, with the lenses consisting of spherical or aspherical lenses. With the increase of the incident angle of light, the lens with the refraction structure is difficult to avoid the distortion, chromatic aberration and coma aberration of an image plane, so that the projection ratio is difficult to be continuously reduced under the condition of ensuring the image quality.
At present, a plurality of structures based on the design principle of a refraction and transmission structure are proposed, but the structures can not well control optical parameters such as chromatic aberration, spherical aberration, coma aberration, distortion and the like of imaging while reducing the projection ratio, and can not ensure the brightness and the depth of field of an image surface. In addition, since the cemented lens or the aspherical lens used in the prior art has two or more lenses, it is difficult to ensure the processing precision and the processing cost is increased.
Disclosure of Invention
The embodiment of the invention provides a projection lens, which is used for ensuring the processing precision and controlling the processing cost on the premise of reducing the projection ratio.
An embodiment of the present invention provides a projection lens, including:
a display chip for modulating the light beam from the illumination system to display the micro-image;
the prism is used for totally reflecting the light rays coming out of the illuminating system to the display chip;
the refraction lens group is used for balancing the aberration of the image formed by the micro image through the refraction lens group;
and the reflector group is used for turning the light path and correcting the residual aberration of the image formed by the refraction lens group.
Further, the reflector group comprises an aspheric reflector and a spherical reflector;
wherein the refraction lens group and the aspheric reflector have the same main optical axis;
the main optical axis of the spherical reflector and the main optical axis of the aspheric reflector are positioned on different horizontal planes;
the aspheric reflector is used for turning the light path and correcting the residual aberration of the image formed by the refraction lens group;
the spherical reflector is used for turning the light beam reflected by the aspheric reflector so as to project the light beam on a screen.
Further, the aberration of the micro-image balanced by the refractive lens group formed by the image formed by the refractive lens group comprises: spherical aberration, coma, astigmatism, field curvature and chromatic aberration.
Further, the refraction lens group comprises a first lens group, an aperture stop and a second lens group which are sequentially arranged along the optical path;
wherein the first lens group, the aperture stop, and the second lens group have the same principal optical axis.
Further, the first lens group comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens which are sequentially arranged along the light path;
the first lens is a concave-convex lens, the second lens is a biconvex lens, the third lens is a biconvex lens, the fourth lens is a biconcave lens, and the fifth lens is a biconvex lens;
wherein the fourth lens and the fifth lens are glued into a whole.
Further, the second lens group comprises 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 arranged in sequence along the optical path;
the sixth lens element is a biconvex lens, the seventh lens element is a meniscus lens, the eighth lens element is a meniscus lens, the ninth lens element is a biconcave lens, the tenth lens element is a biconvex lens, the eleventh lens element is a meniscus lens, the twelfth lens element is a meniscus lens, the thirteenth lens element is a biconvex lens, the fourteenth lens element is a biconvex lens, and the fifteenth lens element is a meniscus lens;
the twelfth lens is used for adjusting the zooming function so as to enable the picture projected on the screen to be clear by matching with the movement of the projection lens within the preset range.
Further, the display chip is a Digital Micromirror Device (DMD) display chip; the resolution of the DMD display chip is 4k, and the pixel size is 5.4 microns.
Further, the DMD display chip offset is 5.59 millimeters.
Further, the aspheric surface shape of the aspheric reflector is represented by the formula:
the characterization is carried out, wherein z is rise, c is curvature at the vertex of the curved surface, and r is distance between projection of coordinates of the curved surface point on a plane vertical to the optical axis and the optical axisK is the conic coefficient, a1、a2、a3、a4、a5、a6、a7And a8Representing the coefficients corresponding to the even term.
Further, the fifteenth lens is an aspheric lens, and the aspheric surface shape of the fifteenth lens is represented by the formula:
characterizing, wherein z is rise, c is curvature at the vertex of the curved surface, r is the distance between the projection of the coordinate of the curved surface point on the plane vertical to the optical axis and the optical axis, k is a cone coefficient, a1、a2、a3、a4、a5、a6、a7And a8Representing the coefficients corresponding to the even term.
The invention corrects aberration by arranging the aspheric mirror, solves the problems of high installation precision requirement and high processing cost caused by using a plurality of aspheric mirrors, and realizes the effects of ensuring the processing precision and controlling the processing cost.
Drawings
Fig. 1 is a schematic structural diagram of a projection lens according to a first embodiment of the invention;
fig. 2 is a schematic structural diagram of a projection lens according to a second embodiment of the present invention;
fig. 3 is a schematic diagram of an operating principle of a projection lens according to a second embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
Example one
Fig. 1 is a schematic structural diagram of a projection lens according to an embodiment of the present invention, which is applicable to an indoor scene such as a meeting room, and projects a large image in a short distance, and the projection lens includes:
a display chip 0000 for modulating a light beam from the illumination system to display a micro image; wherein, the display chip 0000 is a DMD display chip; illustratively, a DMD display chip having a resolution of 4k and a pixel size of 5.4 microns may be selected. Optionally, the DMD display chip offset is 5.59 millimeters.
A prism 1000 for totally reflecting the light from the illumination system to the display chip 0000;
a refraction lens group 2000 for balancing aberration of the micro image formed by the refraction lens group 2000; the refractive lens group 2000 is a main component of the projection lens, and balances aberration existing in an image in the process of imaging the micro image displayed by the display chip 0000 onto a screen. Illustratively, the aberration of the micro-image balanced by the refractive lens group 2000 through the refractive lens group 2000 includes: spherical aberration, coma, astigmatism, field curvature and chromatic aberration.
The mirror group 3000 is used to turn the optical path and correct the residual aberration of the image formed by the refractive lens group 2000. In which aberrations such as spherical aberration, coma, astigmatism, field curvature, and chromatic aberration are balanced in the refractive lens group 2000, and after these aberrations, aberrations remain, which are mainly distortions. The mirror group 3000 may include an aspherical mirror, thereby functioning to enlarge an image and to turn an optical path, and further correcting a residual distortion aberration.
The invention corrects aberration by arranging the aspheric mirror, solves the problems of high installation precision requirement and high processing cost caused by using a plurality of aspheric mirrors, and realizes the effects of ensuring the processing precision and controlling the processing cost.
Example two
The technical solution of this embodiment is further refined on the basis of the technical solutions of the above embodiments, and optionally, as shown in fig. 2, the refractive lens group 2000 includes a first lens group 2100, an aperture stop 2200, and a second lens group 2300, which are sequentially arranged along the optical path.
Wherein the first lens group 2100, the aperture stop 2200, and the second lens group 2300 have the same main optical axis.
As shown in fig. 2, the first lens group 2100 includes a first lens 2001, a second lens 2002, a third lens 2003, a fourth lens 2004, and a fifth lens 2005 arranged in this order along the optical path;
the first lens 2001 is a meniscus lens, the second lens 2002 is a biconvex lens, the third lens 2003 is a biconvex lens, the fourth lens 2004 is a biconcave lens, and the fifth lens 2005 is a biconvex lens;
the fourth lens 2004 and the fifth lens 2005 are bonded to form a whole.
Alternatively, as shown in fig. 2, the second lens group 2300 includes a sixth lens 2006, a seventh lens 2007, an eighth lens 2008, a ninth lens 2009, a tenth lens 2010, an eleventh lens 2011, a twelfth lens 2012, a thirteenth lens 2013, a fourteenth lens 2014, and a fifteenth lens 2015, which are sequentially arranged along the optical path.
The sixth lens element 2006 is a biconvex lens, the seventh lens element 2007 is a meniscus lens, the eighth lens element 2008 is a meniscus lens, the ninth lens element 2009 is a biconcave lens, the tenth lens element 2010 is a biconvex lens, the eleventh lens element 2011 is a meniscus lens element, the twelfth lens element 2012 is a meniscus lens element, the thirteenth lens element 2013 is a biconvex lens element, the fourteenth lens element 2014 is a biconvex lens element, and the fifteenth lens element 2015 is a meniscus lens element;
the twelfth lens 2012 is used for adjusting the zooming function so as to make the picture projected on the screen clear in coordination with the movement of the projection lens within the preset range.
Alternatively, as shown in fig. 2, the mirror group includes an aspherical mirror 3001 and a spherical mirror 3002.
The refractive lens group 2000 and the aspherical mirror 3001 have the same main optical axis.
The main optical axis of the spherical mirror 3002 and the main optical axis of the aspherical mirror 3001 are on different horizontal planes.
An aspherical mirror 3001 for turning the optical path and correcting the residual aberration of the image formed by the refractive lens group 2000;
the spherical mirror 3002 is used for turning the light beam reflected by the aspheric mirror 3001 to project on the screen.
Alternatively, the aspherical surface type of the aspherical mirror 3001 is represented by the formula:
characterizing, wherein z is rise, c is curvature at the vertex of the curved surface, r is the distance between the projection of the coordinate of the curved surface point on the plane vertical to the optical axis and the optical axis, k is a cone coefficient, a1、a2、a3、a4、a5、a6、a7And a8Representing the coefficients corresponding to the even term.
To achieve a lower throw ratio and further improve the remaining curvature of field and distortion aberrations, several initial profiles of the aspherical mirror are obtained by mathematical algorithms, wherein a further optimization for processing is chosen, resulting in the even aspherical mirror 3001. Although the aspheric order of the concave even-order aspheric reflector 3001 reaches twenty orders, the surface type is good, the manufactured material is aluminum, and the requirements on processing production and assembly are not high.
Alternatively, the fifteenth lens 2015 is an aspheric lens, and the aspheric surface type of the fifteenth lens 2015 is represented by the formula:
characterizing, wherein z is rise, c is curvature at the vertex of the curved surface, r is the distance between the projection of the coordinate of the curved surface point on the plane vertical to the optical axis and the optical axis, k is a cone coefficient, a1、a2、a3、a4、a5、a6、a7And a8Representing the coefficients corresponding to the even term. Optionally, the material of the fifteenth lens 2015 is organic glass PMMAO.
The lens surface type, pitch and material of the refractive lens group 2000 are determined by calculation and subsequent optimization, as well as cost consideration and assembly analysis, according to the optical imaging principle. In order to control the chromatic aberration and spherical aberration of the image, reduce the manufacturing and assembling cost of the whole system, and ensure the final image quality, the refractive lens group 2000 uses a cemented lens. The prism 1000 and the materials from the first lens 2001 to the fourteenth lens 2014 are made of commonly used eco-friendly glass.
The working principle of the ultra-short-focus projection lens system provided by the embodiment of the invention is shown in fig. 3, incident light passes through the prism group 1000 and enters the refraction lens group 2000, and the aberration of the whole imaging system is greatly reduced, such as spherical aberration, coma aberration, astigmatism, field curvature, chromatic aberration and other aberrations, but the distortion is not well improved. Then, the light passes through the aspheric surface mirror 3001, is reflected by the spherical surface mirror 3002, and is reflected to the screen 4000 again for imaging, so as to obtain a projected picture. The aspherical mirror 3001 mainly corrects distortion remaining in the refractive lens group 2000. Thus, a clear projection picture can be obtained.
The ultra-short-focus projection lens system of the embodiment of the invention can achieve the following performance parameters: the projection ratio is 0.155, the magnification is 167 times, the F number is 2.0, the back focus is 27.55mm, high-quality imaging under the resolution of 4k is met, and the vertical TV distortion (TVdistortion) is less than 0.1%, and the horizontal TV distortion is less than 0.2%. The projection ratio is the ratio of the projection distance to the screen width, and within the same working distance, the smaller the projection ratio is, the larger the screen is projected. The 0.155 throw ratio has been greatly superior to the same type of product. The F number determines the image plane illumination and the difficulty of design, and the smaller the F number, the higher the energy utilization rate is, and the aberration is difficult to control. The ultra-short-focus projection lens system can ensure extremely small vertical distortion and horizontal distortion, and lower spherical aberration, astigmatism, coma aberration, chromatic aberration and field curvature under different projection ratios, and is the superior point of the system.
The ultra-short-focus projection lens system provided by the embodiment has lower projection ratio and can ensure 4k resolution. Except for the use of a pair of spherical cemented lens and an aspherical reflector, the whole system has reasonable tolerance distribution after adjustment, reduces the error caused by the assembly of the mechanical structure to the maximum extent, greatly reduces the processing difficulty and is suitable for large-scale production.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. 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, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims (8)
1. A projection lens, comprising:
a display chip for modulating the light beam from the illumination system to display the micro-image;
the prism is used for totally reflecting the light rays coming out of the illuminating system to the display chip;
the refraction lens group is used for balancing the aberration of the image formed by the micro image through the refraction lens group;
the refraction lens group comprises a first lens group, an aperture diaphragm and a second lens group which are sequentially arranged along an optical path;
wherein the first lens group, the aperture stop and the second lens group have the same main optical axis; the first lens group comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens which are sequentially arranged along a light path;
the first lens is a concave-convex lens, the second lens is a biconvex lens, the third lens is a biconvex lens, the fourth lens is a biconcave lens, and the fifth lens is a biconvex lens;
wherein the fourth lens and the fifth lens are glued into a whole;
and the reflector group is used for turning the light path and correcting the residual aberration of the image formed by the refraction lens group.
2. The projection lens of claim 1 wherein the set of mirrors comprises an aspheric mirror and a spherical mirror;
wherein the refraction lens group and the aspheric reflector have the same main optical axis;
the main optical axis of the spherical reflector and the main optical axis of the aspheric reflector are positioned on different horizontal planes;
the aspheric reflector is used for turning the light path and correcting the residual aberration of the image formed by the refraction lens group;
the spherical reflector is used for turning the light beam reflected by the aspheric reflector so as to project the light beam on a screen.
3. The projection lens of claim 1 wherein the aberration of the micro image balanced by the refractive lens group from the image formed by the refractive lens group comprises: spherical aberration, coma, astigmatism, field curvature and chromatic aberration.
4. The projection lens of claim 1 wherein:
the second lens group comprises 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 sixth lens element is a biconvex lens, the seventh lens element is a meniscus lens, the eighth lens element is a meniscus lens, the ninth lens element is a biconcave lens, the tenth lens element is a biconvex lens, the eleventh lens element is a meniscus lens, the twelfth lens element is a meniscus lens, the thirteenth lens element is a biconvex lens, the fourteenth lens element is a biconvex lens, and the fifteenth lens element is a meniscus lens;
the twelfth lens is used for adjusting the zooming function so as to enable the picture projected on the screen to be clear by matching with the movement of the projection lens within the preset range.
5. The projection lens of claim 1 wherein the display chip is a Data Micromirror Device (DMD) display chip; the resolution of the DMD display chip is 4k, and the pixel size is 5.4 microns.
6. The projection lens of claim 5 wherein the DMD display chip offset is 5.59 millimeters.
7. The projection lens of claim 2 wherein the aspheric surface profile of the aspheric mirror is defined by the formula:
characterizing, wherein z is rise, c is curvature at the vertex of the curved surface, r is the distance between the projection of the coordinate of the curved surface point on the plane vertical to the optical axis and the optical axis, k is a cone coefficient, a1、a2、a3、a4、a5、a6、a7And a8Representing the coefficients corresponding to the even term.
8. The projection lens as claimed in claim 4, wherein the fifteenth lens is an aspheric lens, and the aspheric surface of the fifteenth lens is defined by the formula:
characterizing, wherein z is rise, c is curvature at the vertex of the curved surface, r is the distance between the projection of the coordinate of the curved surface point on the plane vertical to the optical axis and the optical axis, k is a cone coefficient, a1、a2、a3、a4、a5、a6、a7And a8Representing the coefficients corresponding to the even term.
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| CN108305231B (en) * | 2018-02-09 | 2021-08-27 | 西安电子科技大学 | Lens distortion correction method in maskless photoetching technology |
| CN112180660A (en) * | 2019-07-04 | 2021-01-05 | 无锡视美乐激光显示科技有限公司 | DLP (digital light processing) illuminating system and projecting device using aspheric reflector |
| CN112269298A (en) * | 2020-11-24 | 2021-01-26 | 四川长虹电器股份有限公司 | Curved surface projection optical system |
| CN113504633B (en) * | 2021-06-29 | 2022-10-18 | 青岛海信激光显示股份有限公司 | Projection system |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104181695A (en) * | 2013-05-20 | 2014-12-03 | 株式会社理光 | Projection optical system and image display apparatus |
| CN104914651A (en) * | 2014-03-14 | 2015-09-16 | 林伊柔 | Projector, and projection lens and projection method thereof |
| CN106842590A (en) * | 2017-03-28 | 2017-06-13 | 中山联合光电科技股份有限公司 | A kind of ultrashort out-of-focus projection's optical system |
| CN107015425A (en) * | 2017-03-26 | 2017-08-04 | 南京悦微米智能科技有限公司 | A kind of ultrashort out-of-focus projection's instrument lens systems of LED |
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| JP4223936B2 (en) * | 2003-02-06 | 2009-02-12 | 株式会社リコー | Projection optical system, enlargement projection optical system, enlargement projection apparatus, and image projection apparatus |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104181695A (en) * | 2013-05-20 | 2014-12-03 | 株式会社理光 | Projection optical system and image display apparatus |
| CN104914651A (en) * | 2014-03-14 | 2015-09-16 | 林伊柔 | Projector, and projection lens and projection method thereof |
| CN107015425A (en) * | 2017-03-26 | 2017-08-04 | 南京悦微米智能科技有限公司 | A kind of ultrashort out-of-focus projection's instrument lens systems of LED |
| CN106842590A (en) * | 2017-03-28 | 2017-06-13 | 中山联合光电科技股份有限公司 | A kind of ultrashort out-of-focus projection's optical system |
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