CN113504633B

CN113504633B - Projection system

Info

Publication number: CN113504633B
Application number: CN202110725539.3A
Authority: CN
Inventors: 阴亮
Original assignee: Qingdao Hisense Laser Display Co Ltd
Current assignee: Qingdao Hisense Laser Display Co Ltd
Priority date: 2021-06-29
Filing date: 2021-06-29
Publication date: 2022-10-18
Anticipated expiration: 2041-06-29
Also published as: CN113504633A

Abstract

The invention discloses a projection system, comprising: the projection lens is positioned on the light emitting side of the light valve modulation component; the projection lens includes: the refraction system is positioned on the light emitting side of the light valve modulation component and is used for imaging the image light emitted by the light valve modulation component; and the reflecting system is positioned on one side of the refracting system, which is far away from the light valve modulating component, and is used for reflecting the imaging light of the refracting system to one side of the light valve modulating component, which is far away from the projection lens. The projection lens in the projection system provided by the embodiment of the invention is an ultra-short-focus lens, the refraction system and the reflection system participate in imaging, and the reflection system can reflect the projection light to one side of the light valve modulation component away from the refraction system, so that in specific application, the projection screen can be arranged on the back of the light valve modulation component, the distance between the projection screen and the projection system is reduced, the projection system can be arranged between a viewer and the projection screen, the problem that the picture is shielded is avoided, and the use space is saved.

Description

Projection system

Technical Field

The invention relates to the technical field of projection display, in particular to a projection system.

Background

The projection display is a method or an apparatus for controlling a light source by plane image information, enlarging and displaying an image on a projection screen using an optical system and a projection space. With the development of projection display technology, projection display is gradually applied to the fields of business activities, conference exhibition, scientific education, military command, traffic management, centralized monitoring, advertising entertainment and the like, and the advantages of large display picture size, clear display and the like are also suitable for the requirement of large-screen display.

The lens is one of core technologies in projection display, and has certain difficulty from design to processing. The distance between the current projection lens and a projection screen or a wall is far, and if an object moves between the lens and the screen, projection light can be shielded, so that picture display is influenced.

Disclosure of Invention

In some embodiments of the present invention, the projection lens includes an ultra-short focus lens formed by a refraction system and a reflection system, both of which participate in imaging, and the reflection system can reflect the projection light to a side of the light valve modulation component away from the refraction system, so that in specific applications, the projection screen can be disposed on the back of the light valve modulation component, and the distance between the projection screen and the projection system is reduced, so that the projection system can be disposed between a viewer and the projection screen, thereby avoiding the problem of image shielding and saving the use space.

In some embodiments of the present invention, the refractive system comprises a front group lens, a middle group lens and a rear group lens, the front group lens is movable relative to the reflective system, thereby achieving better distortion performance in different sizes, and the relative displacement between the middle group lens and the front group lens is adjustable, thereby achieving focused imaging in different projection 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, a seventh lens, an eighth lens, a ninth lens, and a tenth lens sequentially disposed along the light exiting direction of the light valve modulating component. The first lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens and the tenth lens are all spherical lenses; the second lens is an aspheric lens. The second lens sets up and adopts aspheric lens can rectify spherical aberration and coma, improves projection lens's resolution.

In some embodiments of the present invention, the second lens is a biconvex aspheric lens.

In some embodiments of the present invention, an aperture stop is disposed between the seventh lens and the eighth 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 third lens and the fourth lens form a first cemented doublet group, the fifth lens, the sixth lens and the seventh lens form a third cemented doublet group, and the ninth lens and the tenth lens form a second cemented doublet group. The double-gluing and the triple-gluing are used in a matching way, the spectrum application range of the lens is expanded to 450 nm-645 nm, and chromatic aberration is effectively corrected.

In some embodiments of the present invention, the middle lens group includes an eleventh lens and a twelfth lens sequentially arranged along the light exiting direction of the rear lens group; wherein, the eleventh lens and the twelfth lens are both ball lenses. The diopter of the eleventh lens is positive, and the diopter of the twelfth lens is positive.

In some embodiments of the present invention, the front lens group includes a thirteenth lens, a fourteenth lens and a fifteenth lens sequentially arranged along the light exiting direction of the middle lens group; wherein, the thirteenth lens and the fourteenth lens are both spherical lenses; the fifteenth lens is an aspheric lens. Diopter of the thirteenth lens is positive, diopter of the fourteenth lens is negative, and diopter of the fifteenth lens is negative. The fifteenth lens adopts an aspheric lens to effectively improve astigmatism and distortion.

In some embodiments of the present invention, the fifteenth lens is a biconcave aspheric lens.

In some embodiments of the present invention, the reflective system employs a concave mirror for compressing the angle of the light.

In some embodiments of the invention, the reflecting system adopts an aspheric reflector or a free-form surface reflector, so that light can be effectively compressed and astigmatism and distortion can be corrected.

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:

1.5<|FB/F|<7.5；

5<|FM/F|<15；

1<|FF/F|<12；

5<|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 present invention, the projection ratio of the projection lens is 0.2 to 0.3, and specifically may be 0.2 to 0.25.

In some embodiments of the invention, the refractive system and the reflective system satisfy the following relationship:

0.9<L1/L2<1.2；

the rear working distance of the projection lens meets the following relation:

0.25<BFL/L2<0.4；

wherein L1 denotes a total 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.

In some embodiments of the present invention, the aspheric lens is disposed in the rear lens group to increase the rear working distance, and the image shift lens group may be disposed between the light valve modulation unit and the projection lens to realize high-resolution image display.

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 system according to an embodiment of the present invention;

FIG. 2 is a second schematic view of a projection system according to an embodiment of the present invention;

FIG. 3 is a third schematic view illustrating a structure of a projection system according to an embodiment of the present invention;

FIG. 4 is a lateral chromatic aberration diagram of a projection system provided by an embodiment of the present invention;

fig. 5 is a TV distortion curve provided by an embodiment of the present invention.

The system comprises a light valve modulation component 100, a projection lens 200, a beam splitter 300, a projection light source 400, an image deflection mirror 500, a projection screen 600, a refraction system 20a, a reflection system 20b, a front mirror 201, a middle mirror 202, a rear mirror 203, a first lens 21, a second lens 22, a third lens 23, a fourth lens 24, a fifth lens 25, a sixth lens 26, a seventh lens 27, an eighth lens 28, a ninth lens 29, a tenth lens 210, an eleventh lens 211, a twelfth lens 212, a thirteenth lens 213, a fourteenth lens 214, a fifteenth lens 215, a first doublet x-lens group x1, a triplet cemented lens group x2, a doubly cemented lens group x3, a doubly cemented lens group d, and an aperture diaphragm d.

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 indicating positions and directions in the present invention are illustrated by way of example in the accompanying drawings, but may be changed as required and are within the scope of the present invention. The drawings of the present invention are for illustrative purposes only and do not represent true scale.

The projection display is a method or an apparatus for controlling a light source by plane image information, enlarging and displaying an image on a projection screen using an optical system and a projection space. With the development of projection display technology, projection display is gradually applied to the fields of business activities, conference exhibition, scientific education, military command, traffic management, centralized monitoring, advertising and entertainment and the like, and the advantages of large display screen size, clear display and the like are also suitable for the requirement of large-screen display.

A commonly used projection system is a Digital Light Processing (DLP) architecture, and a Digital micro mirror Device (DMD) is used as a core Device, and Light emitted from a projection Light source is incident on the DMD to generate an image, and then the Light emitted from the image generated by the DMD is incident on a projection lens, is imaged by the projection lens, and is 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.

In view of this, embodiments of the present invention provide a projection system, which employs an ultra-short-focus projection lens to reduce a distance between the projection system and a projection screen, so as to avoid a problem that a projection image is blocked.

Fig. 1 is a schematic structural diagram of a projection system according to an embodiment of the present invention.

As shown in fig. 1, a projection system provided in an embodiment of the present invention includes: a light valve modulating component 100 and a projection lens 200 positioned on the light exit side of the light valve modulating component.

The light valve modulation component 100 is a core Device of the whole projection system, and may adopt a Digital Micromirror Device (DMD). The monolithic DMD application will be described below as an example. The DMD is a reflective light valve device, light emitted from a projection light source illuminates the DMD in accordance with an illumination size and an incident angle required by the DMD, the surface of the DMD includes thousands of tiny mirrors, each tiny mirror can be independently driven to deflect, the reflected light is incident to the projection lens 200 by controlling the deflection angle of the DMD, and is used for projection imaging after being imaged by the projection lens.

The projection lens 200 includes: a refractive system 20a and a reflective system 20b.

And a refractive system 20a located on the light-emitting side of the light valve modulating part 100 for imaging the image light emitted from the light valve modulating part 200.

And a reflection system 20b, located on a side of the refraction system 20a facing away from the light valve modulation component 100, for reflecting the imaging light of the refraction system to a side of the light valve modulation component facing away from the projection lens.

The projection lens in the projection system provided by the embodiment of the invention is an ultra-short-focus lens, the refraction system and the reflection system participate in imaging, and the reflection system can reflect the projection light to the side, away from the refraction system, of the light valve modulation component, so that in specific application, the projection screen can be arranged on the back of the light valve modulation component, the distance between the projection screen and the projection system is reduced, the projection system can be arranged between a viewer and the projection screen, the problem that pictures are shielded is avoided, and meanwhile, the use space is saved.

As shown in fig. 1, a refraction system 20a in the projection lens includes: a front group lens 201, a middle group lens 202 and a rear group lens 203; the front lens group 201 is located at a side close to the reflection system 20 b; the middle lens group 202 is located on the side of the front lens group 201 away from the reflection system 20 b; the rear group lens 203 is located on a side of the middle group lens 202 away from the front group lens 201. The reflective system 20b employs a concave mirror.

The reflecting system 20b, the front group lens 201, the middle group lens 202 and the rear group lens 203 are coaxially arranged. The reflection system 20b, the front group lens group 201 and the middle group lens group 202 are mainly used for compressing light rays, so that the projection system has a proper projection ratio and can realize image display with larger size; the front lens group 203 is used to improve image resolution.

In the embodiment of the present invention, the front group lens assembly 201 is movable relative to the reflection system 20b, so that better distortion performance is achieved in different sizes, and the relative displacement between the middle group lens assembly 202 and the front group lens assembly 201 is adjustable, so that focusing imaging in different projection sizes can be achieved.

The existing ultra-short focus lens is designed based on a monochromatic product, the spectral range usually only covers 450-620 nm, and with the maturity of a three-color laser light source technology, the monochromatic lens is used for three-color imaging, so that the problem of large deviation of red, green and blue pixels inevitably exists, and the imaging quality is seriously influenced.

The embodiment of the invention provides an ultra-short focal lens which is suitable for full-color laser spectrum and solves the problem that the three colors of red, green and blue have large deviation under the full-spectrum condition of the existing lens.

Specifically, as shown in fig. 1, the rear group lens 203 includes a first lens 21, a second lens 22, a third lens 23, a fourth lens 24, a fifth lens 25, a sixth lens 26, a seventh lens 27, an aperture stop d, an eighth lens 28, a ninth lens 29, and a tenth lens 210, which are arranged in this order in the light exit direction of the light valve modulating section 100.

The first lens 21, the third lens 23, the fourth lens 24, the fifth lens 25, the sixth lens 26, the seventh lens 27, the eighth lens 28, the ninth lens 29 and the tenth lens 210 are all spherical lenses; the second lens 22 is an aspherical lens.

In the embodiment of the present invention, the aspherical mirror is disposed in the rear lens group near the light valve modulation component 100, so that spherical aberration and coma aberration can be corrected, and the resolution of the projection lens can be improved. In a specific implementation, the lens near the light valve modulation component may be set to be an aspheric lens, for example, the first lens 21 or the second lens 22 may be set to be an aspheric lens, and the second lens 22 may be set to be an aspheric lens, which may reduce the processing precision and improve the manufacturability design compared to the case that the first lens 21 is set to be an aspheric lens. In addition, the second lens 22 can also increase the rear working distance of the lens (the distance from the light valve modulation component to the first lens) by adopting an aspheric lens, so that an image shift mirror group can be arranged at the position to realize high-resolution image display.

In some embodiments, the diopter of the first lens 21 is positive, the diopter of the second lens 22 is positive, the diopter of the third lens 23 is positive, the diopter of the fourth lens 24 is negative, the diopter of the fifth lens 25 is positive, the diopter of the sixth lens 26 is negative, the diopter of the seventh lens 27 is positive, the diopter of the eighth lens 28 is positive, the diopter of the ninth lens 29 is positive, and the diopter of the tenth lens 210 is negative.

Among them, the second lens 22 may employ a biconvex aspherical lens.

The third lens 23 and the fourth lens 24 are cemented with each other to constitute a first cemented doublet group x1. The abbe number of the fourth lens 24 is smaller than that of the third lens 23, and the refractive index of the fourth lens 24 is larger than that of the third lens 23. The value range of the abbe number vd3 of the third lens 23 is as follows: 70-vd3-90, and the refractive index nd3>1.45 of the third lens 23. When the optical design is performed, the third lens and the fourth lens can be processed by selecting appropriate materials according to the value range.

The fifth lens 25, the sixth lens 26, and the seventh lens 27 are cemented with each other to constitute a triple cemented lens group x2. The refractive index of the fifth lens 25 and the refractive index of the seventh lens 27 are both smaller than the refractive index of the sixth lens 26, and the abbe numbers of the fifth lens 25 and the seventh lens 27 are both larger than the abbe number of the sixth lens 26. The value range of the abbe number vd6 of the sixth lens is as follows: 17-sd6-woven fabric(s) are (n) 30, and the refractive index nd6 of the sixth lens is >1.85. When optical design is performed, appropriate materials can be selected according to the value range to process the fifth lens, the sixth lens and the seventh lens.

The ninth lens 29 and the tenth lens 210 are cemented with each other to constitute a second cemented-doublet lens group x3. The abbe number of the ninth lens 29 is smaller than that of the tenth lens 210, and the refractive index of the ninth lens 29 is larger than that of the tenth lens 210. Wherein a refractive index difference Δ nd between the ninth lens 29 and the tenth lens 210 satisfies: and delta nd is more than or equal to 0 and less than or equal to 0.1. When the optical design is performed, the ninth lens and the tenth lens can 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 spectrums, so that the spectrum of the projection lens provided by the embodiment of the invention covers the range of 450nm to 645nm. The three groups of cemented lens groups x2 are used for improving the spherical aberration of different spectrums of the projection lens and correcting the axial chromatic aberration and the vertical axis chromatic aberration of the lens, and the first doubly-cemented lens group x1 and the second doubly-cemented lens group x3 are used for correcting the residual axial chromatic aberration and the coma aberration of the system. 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.

As shown in fig. 1, the middle group lens 202 includes an eleventh lens 211 and a twelfth lens 212 arranged in this order in the light exit direction of the rear group lens 201; the eleventh lens 211 and the twelfth lens 212 are both ball lenses. The refractive power of the eleventh lens 211 is positive, and the refractive power of the twelfth lens 212 is positive.

The front group lens group 201 includes a thirteenth lens 213, a fourteenth lens 214, and a fifteenth lens 215, which are arranged in this order along the light exit direction of the middle group lens group 202; wherein, the thirteenth lens 213 and the fourteenth lens 214 are both spherical lenses; the fifteenth lens 215 is an aspherical lens. A dioptre of the thirteenth lens 213 is positive, a dioptre of the fourteenth lens 214 is negative, and a dioptre of the fifteenth lens 215 is negative.

The front and middle groups of

mirrors

201 and 202 further compress the reflected light of the reflection system 20b. By adjusting the relative distances among the front group lens assembly 201, the middle group lens assembly 202 and the reflection system 20b, image display with different sizes can be realized, and simultaneously, projected images can be clearly imaged on the projection screen.

In the embodiment of the present invention, an aspherical mirror is disposed in the front lens group near the side of the reflection system 20b for correcting distortion. In one embodiment, the reflection system 20b compresses the light in a large proportion, and the fifteenth lens 215 is configured as an aspheric lens to effectively improve astigmatism and distortion. In practical applications, the fifteenth lens 215 may be a biconcave aspheric lens.

The reflection system 20b may employ a concave mirror for compressing the light angle, and specifically may employ an aspherical mirror or a free-form surface mirror. In the embodiment of the present invention, the reflection system 20b 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, so astigmatism and distortion can be effectively corrected by using the aspherical mirror and the free-form surface mirror.

Further, an aperture stop d is provided between the seventh lens 27 and the eighth lens 28, and the amount of light transmitted through the projection lens is limited, and light rays having large aberrations at the edge position can be shielded in accordance with the F number of the projection lens.

According to practical use requirements, the embodiment of the invention also limits the focal length of the projection lens of the framework. Specifically, 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:

1.5<|FB/F|<7.5；

5<|FM/F|<15；

1<|FF/F|<12；

5<|FC/F|<12；

where F denotes an equivalent focal length of the projection lens 200, FB denotes an equivalent focal length of the rear group lens 201, FM denotes an equivalent focal length of the middle group lens 202, FF denotes an equivalent focal length of the front group lens 203, and FC denotes an equivalent focal length of the reflection system 20b.

The refractive system 20a and the reflective system 20b in the projection lens integrally generate positive diopter for converging light. The projection lens 200 adopts a secondary imaging structure, the light beam emitted from the light valve modulation component 100 passes through the refraction system 20a and then is imaged between the reflection system 20b and the refraction system 20a for the first time, and the first imaging is reflected by the reflection system 20b to form a secondary undistorted image on a projection screen.

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 ultra-short-focus projection lens provided by the embodiment of the invention can be 0.2-0.3, and actually can reach 0.2-0.25, so that the use requirement of ultra-short focus is met, the distance between a projector and a projection screen is greatly shortened, and the image display of 70-100 inches can be realized while the projection distance is shortened.

The refractive system 20a and the reflective system 20b satisfy the following relationship:

0.9<L1/L2<1.2；

the rear working distance of the projection lens 200 satisfies the following relationship:

0.25<BFL/L2<0.4；

By adopting the design of appropriate surface type and diopter for each lens in the front group lens group 201, the middle group lens group 202 and the rear group lens group 203, the number of the lenses is controlled, the miniaturization is realized, and the full-color laser projection display is suitable. The single-lens chromatic aberration correction lens greatly reduces the complexity and the volume of the lens by only using 1-2 aspheric lenses, expands the spectrum application range of the lens from original 450-620 nm to 450-645 nm by matching double-gluing and triple-gluing, solves the problem of large chromatic aberration deviation of the single-color lens, and greatly improves the volume, the complexity, the cost and the processing aspect.

The increase of the rear working distance can enable an image shift mirror group to be arranged between the light valve modulation component 100 and the projection lens, thereby realizing high-resolution image display.

Fig. 2 is a second schematic structural diagram of a projection system according to an embodiment of the invention.

As shown in fig. 2, the projection system further includes: a beam splitter 300, a projection light source 400 and an image shift mirror group 500.

The beam splitter prism 300 is positioned between the light valve modulation component 100 and the projection lens 200, and the light valve modulation component 100 is positioned on the reflection path of the beam splitter prism 300; the projection light source 400 is located on the light incident side of the beam splitter prism 300. The light emitted from the projection light source 400 passes through the light uniformizing component and the illumination light path and then irradiates onto the beam splitter 300 in a suitable size, the beam splitter 300 reflects the light of the light source onto the light valve modulating component 100, for example, the light valve modulating component 100 adopts a DMD, the DMD modulates the source light and then reflects the modulated source light, and then the projection light emitted from the DMD passes through the beam splitter 300 and then enters into the projection lens 200.

Still be provided with image skew mirror group 500 between beam splitter 300 and projection lens 200, image skew mirror group 500 can adopt plate glass, and its plane can produce the angle change, when image skew mirror group 500 is placed between the angle in the difference and is shaken with the higher frequency, can project DMD emergent ray to projection lens's different positions to realize the skew of image, cooperate DMD so with its vibration frequency switching data, can realize the image display of high resolution under the prerequisite that does not change DMD physical resolution.

Fig. 3 is a third schematic structural diagram of a projection system according to an embodiment of the present invention.

Referring to fig. 3, the projection system provided in the embodiment of the present invention may further include a projection screen 600, where the projection screen 600 may be a curtain assembled with the projection system, or may be a wall surface, and is not limited herein. As can be seen from fig. 3, the final image after being imaged by the projection lens 200 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 achieving ultra-short focus projection display.

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-3.85 mm, the offset (the ratio of the distance between the center of the emergent light of the light valve modulation component 100 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. 4 is a lateral chromatic aberration diagram of a projection system according to an embodiment of the present invention, where the abscissa represents lateral chromatic aberration, which may also be referred to as vertical axis chromatic aberration; the ordinate represents the field of view or object height.

As shown in fig. 4, the width of one pixel is p, the dotted line represents a chromatic aberration curve corresponding to a wavelength band of 450nm to 550nm, and the solid line represents a chromatic aberration curve corresponding to a wavelength band of 450nm to 645nm. As can be seen from fig. 4, the color difference between the red, green, and blue bands is equal to or less than 0.3 pixel. The projection lens provided by the embodiment of the invention can effectively improve the chromatic aberration generated by different primary color lights, and the spectrum is expanded to 450 nm-645 nm.

Fig. 5 is a TV distortion plot provided by an embodiment of the present invention, with the horizontal axis representing the x-direction and the vertical axis representing the y-direction.

The TV distortion can reflect the distortion degree of the projection image of the projection system, as shown in fig. 5, the TV distortion of the projection system using the projection lens provided by the embodiment of the present invention is less than or equal to 0.2%, which can meet the actual use requirements.

According to the first invention concept, the projection lens is an ultra-short focus lens formed by the refraction system and the reflection system, both the refraction system and the reflection system participate in imaging, and the reflection system can reflect the projection light to one side of the light valve modulation component, which is far away from the refraction system, so that in specific application, the projection screen can be arranged on the back of the light valve modulation component, the distance between the projection screen and the projection system is reduced, the projection system can be arranged between a viewer and the projection screen, the problem that the picture is shielded is avoided, and meanwhile, the use space is saved.

According to the second inventive concept, the refractive system includes a front group lens, a middle group lens and a rear group lens, the front group lens is movable with respect to the reflective system, thereby achieving better distortion performance in different sizes, and the relative displacement between the middle group lens and the front group lens is adjustable, thereby achieving focused imaging in different projection sizes.

According to a third inventive concept, the rear group lens includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens, and a tenth lens, which are sequentially disposed in a light exit direction of the light valve modulating part. The first lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens and the tenth lens are all spherical lenses; the second lens is an aspheric lens. The second lens adopts aspheric lens to correct spherical aberration and coma aberration, and improves the resolution of the projection lens.

According to the fourth inventive concept, the second lens is a biconvex aspherical lens.

According to the fifth inventive concept, the aperture stop is arranged between the seventh lens and the eighth lens, so that the light flux of the projection lens can be limited, the light flux is adaptive to the F number of the projection lens, and light rays with large aberration at the edge position are shielded.

According to the sixth inventive concept, the third lens and the fourth lens constitute a first cemented doublet group, the fifth lens, the sixth lens and the seventh lens constitute a third cemented doublet group, and the ninth lens and the tenth lens constitute a second cemented doublet group. The double-gluing and the triple-gluing are used in a matching way, the spectrum application range of the lens is expanded to 450 nm-645 nm, and chromatic aberration is effectively corrected.

According to a seventh inventive concept, the middle lens group includes an eleventh lens and a twelfth lens sequentially arranged along the light exit direction of the rear lens group; wherein, the eleventh lens and the twelfth lens are both ball lenses. The diopter of the eleventh lens is positive, and the diopter of the twelfth lens is positive.

According to the eighth inventive concept, the front group lens includes a thirteenth lens, a fourteenth lens and a fifteenth lens sequentially arranged along the light exit direction of the middle group lens; wherein, the thirteenth lens and the fourteenth lens are both spherical lenses; the fifteenth lens is an aspheric lens. Diopter of the thirteenth lens is positive, diopter of the fourteenth lens is negative, and diopter of the fifteenth lens is negative. The fifteenth lens adopts an aspheric lens to effectively improve astigmatism and distortion.

According to the ninth inventive concept, the fifteenth lens is a biconcave aspheric lens.

According to the tenth inventive concept, the reflection system employs a concave mirror for compressing the light angle.

According to the eleventh invention, the reflection system uses an aspherical mirror or a free-form surface mirror, and can effectively compress light and correct astigmatism and distortion.

According to the twelfth inventive concept, 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:

1.5<|FB/F|<7.5；

5<|FM/F|<15；

1<|FF/F|<12；

5<|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.

According to the thirteenth inventive concept, the projection ratio of the projection lens is 0.2 to 0.3, and specifically, may be 0.2 to 0.25.

According to the fourteenth inventive concept, the refractive system and the reflective system satisfy the following relationship:

0.9<L1/L2<1.2；

the rear working distance of the projection lens meets the following relation:

0.25<BFL/L2<0.4；

According to the fifteenth inventive concept, an aspheric lens is disposed in the rear lens group to increase the rear working distance, and an image shift lens group may be disposed between the light valve modulating unit and the projection lens, thereby implementing high-resolution image display.

According to the sixteenth invention concept, the projection lens has a compact overall architecture, and the resolving power of the projection lens is improved by setting the aperture diaphragm, the aspheric lens and the aspheric mirror or the free-form surface mirror to correct the aberration of the large field of view, so that high-quality image display can be realized in the spectral range of 450nm to 645nm.

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

1. A projection system, comprising: the projection lens comprises a light valve modulation component and a projection lens positioned on the light emitting side of the light valve modulation component; the projection lens includes:

the refraction system is positioned on the light emitting side of the light valve modulation component and is used for imaging the image light emitted by the light valve modulation component;

the reflecting system is positioned on one side of the refraction system, which is far away from the light valve modulation component, and is used for reflecting the imaging light rays of the refraction system to one side of the light valve modulation component, which is far away from the projection lens;

the refraction system includes:

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 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:

1.5＜|FB/F|＜7.5；

5＜|FM/F|＜15；

1＜|FF/F|＜12；

5＜|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.

2. The projection system of claim 1, wherein the reflective system, the front lens group, the middle lens group, and the rear lens group are coaxially disposed; the relative distance among the front group lens, the middle group lens and the reflecting system is adjustable.

3. The projection system of claim 2, wherein the rear group lens includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an aperture stop, an eighth lens, a ninth lens, and a tenth lens, which are arranged in this order along the light exit direction of the light valve modulating section;

wherein the first lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, the eighth lens, the ninth lens, and the tenth lens are all spherical lenses; the second lens is an aspheric lens.

4. The projection system of claim 3, wherein a refractive power of the first lens is positive, a refractive power of the second lens is positive, a refractive power of the third lens is positive, a refractive power of the fourth lens is negative, a refractive power of the fifth lens is positive, a refractive power of the sixth lens is negative, a refractive power of the seventh lens is positive, a refractive power of the eighth lens is positive, a refractive power of the ninth lens is positive, and a refractive power of the tenth lens is negative;

the third lens and the fourth lens are mutually glued; the Abbe number of the fourth lens is smaller than that of the third lens, and the refractive index of the fourth lens is larger than that of the third lens;

the fifth lens, the sixth lens and the seventh lens are cemented with each other; the refractive index of the fifth lens and the refractive index of the seventh lens are both smaller than the refractive index of the sixth lens, and the Abbe numbers of the fifth lens and the seventh lens are both larger than the Abbe number of the sixth lens;

the ninth lens and the tenth lens are cemented to each other; the Abbe number of the ninth lens is smaller than that of the tenth lens, and the refractive index of the ninth lens is larger than that of the tenth lens.

5. The projection system of claim 2, wherein the middle lens group includes an eleventh lens and a twelfth lens arranged in this order along the light exit direction of the rear lens group;

wherein the eleventh lens and the twelfth lens are both ball lenses.

6. The projection system of claim 5, wherein the power of the eleventh lens is positive and the power of the twelfth lens is positive.

7. The projection system of claim 2, wherein the front group lens includes a thirteenth lens, a fourteenth lens and a fifteenth lens arranged in this order along the light exit direction of the middle group lens;

wherein the thirteenth lens and the fourteenth lens are both spherical lenses; the fifteenth lens is an aspheric lens.

8. The projection system of claim 7, wherein a refractive power of the thirteenth lens is positive, a refractive power of the fourteenth lens is negative, and a refractive power of the fifteenth lens is negative.

9. The projection system of any of claims 2-8, wherein the reflective system is a concave mirror; the concave reflector is an aspheric reflector or a free-form surface reflector.

10. The projection system of any of claims 1-8, wherein the projection lens has a throw ratio of 0.2 to 0.3;

the refractive system and the reflective system satisfy the following relationship:

0.9＜L1/L2＜1.2；

the rear working distance of the projection lens meets the following relation:

0.25＜BFL/L2＜0.4；

wherein L1 represents a total length of the refractive system, L2 represents a distance between the refractive system and the reflective system, and BFL represents a rear working distance of the projection lens.

11. The projection system of any of claims 1-8, further comprising:

the light valve modulation component is positioned on a reflection path of the light splitting prism;

the projection light source is positioned on the light incidence side of the beam splitter prism;

and the image shift mirror group is positioned between the beam splitter prism and the projection lens.