CN114545713A

CN114545713A - Projection optical system and electronic equipment

Info

Publication number: CN114545713A
Application number: CN202111671867.6A
Authority: CN
Inventors: 郑泓祐
Original assignee: Goertek Optical Technology Co Ltd
Current assignee: Goertek Optical Technology Co Ltd
Priority date: 2021-12-31
Filing date: 2021-12-31
Publication date: 2022-05-27
Anticipated expiration: 2041-12-31
Also published as: CN114545713B

Abstract

The application discloses a projection optical system and an electronic device. The projection optical system includes, in order from the enlargement side to the reduction side: the lens comprises a curved reflector, a first lens group and a second lens group; the focal power of the first lens group is negative, and the focal power of the second lens group is positive; the first lens group comprises a movable lens group which can move along an optical axis; the moving lens group comprises a second lens and a third lens, and the focal powers of the second lens and the third lens are opposite.

Description

Projection optical system and electronic equipment

Technical Field

The present application relates to the field of optical device technology, and more particularly, to a projection optical system and an electronic apparatus.

Background

With the development of projection technology in recent years, projectors have been widely used in various scenes, and among them, ultra-short-focus projection apparatuses have been widely used in the fields of home and office, etc. due to their short distance and large projection screen.

The conventional ultra-short-focus lens generally divides the lens into 3-4 lens group components, and in order to realize focusing at different projection distances, the lens group components 2-3 need to be moved simultaneously to achieve the purpose. The larger the number of movable lens group parts, the more mechanical structures are required for adjustment, or the more complicated the focusing procedure of the lens. In addition, the conventional ultra-short focus lens has distortion when the size of a projected picture is increased, so that the picture quality is influenced.

Disclosure of Invention

An object of the present application is to provide a projection optical system and a new technical solution for an electronic device.

According to a first aspect of embodiments of the present application, there is provided a projection optical system. The device comprises the following components in sequence from an amplification side to a reduction side: the lens comprises a curved reflector, a first lens group and a second lens group;

the focal power of the first lens group is negative, and the focal power of the second lens group is positive;

the first lens group comprises a movable lens group which can move along an optical axis;

the moving lens group comprises a second lens and a third lens, and the focal powers of the second lens and the third lens are opposite.

Optionally, the first lens group further includes a fixed lens group located between the curved reflector and the moving lens group;

the fixed lens group comprises at least one fourth lens with negative focal power.

Optionally, the second lens group comprises: a diaphragm, fifth and sixth lenses located on a first side of the diaphragm, seventh and eighth lenses located on a second side of the diaphragm, and at least two sets of cemented lenses located between the seventh and eighth lenses; the first side is opposite to the second side, and the first side is closer to the first lens group;

the fifth lens and the sixth lens are both aspheric lenses;

the eighth lens is farther from the diaphragm than the seventh lens, and the eighth lens is an aspheric lens.

Optionally, the optical powers of the fifth lens and the sixth lens are opposite.

Optionally, the refractive index Nd of the fifth lens is less than 1.7; the refractive index Nd of the sixth lens is less than 1.7.

Optionally, the seventh lens is an aspheric lens.

Optionally, a twelfth lens, a thirteenth lens, a fourteenth lens and a fifteenth lens are sequentially disposed between the seventh lens and the eighth lens; the two groups of cemented lenses include a first cemented lens and a second cemented lens;

the twelfth lens and the thirteenth lens are connected in a gluing mode to form a first gluing lens;

the fourteenth lens and the fifteenth lens are in glued joint to form a second cemented lens.

Optionally, the optical powers of the twelfth lens and the thirteenth lens are opposite; the optical power of the fourteenth lens is opposite to that of the fifteenth lens.

Alternatively, the second lens group includes, in order from the magnification side to the reduction side: a ninth lens, a tenth lens, a fifth lens, a sixth lens, an eleventh lens, a seventh lens, a twelfth lens, a thirteenth lens, a fourteenth lens, a fifteenth lens, and an eighth lens, wherein a stop is disposed between the eleventh lens and the seventh lens;

the focal power of the second lens group is sequenced as follows: positive negative plus/negative positive plus.

Optionally, the fifth lens, the sixth lens and the eighth lens are all aspheric lenses.

Optionally, the twelfth lens is cemented with the thirteenth lens to form a first cemented lens;

Optionally, the curved mirror is a concave mirror.

Optionally, the second lens and the third lens are cemented together to form a third cemented lens.

According to a second aspect of the embodiments of the present application, an electronic device is provided. The electronic device includes the projection optical system according to the first aspect.

One technical effect of the present application is to provide a projection optical system, which can reduce a projection ratio and improve image quality by combining and matching a curved reflector, a first lens group and a second negative power lens group; in addition, the focusing of the projection optical system is realized through a group of movable lens groups, and the complexity and the operation difficulty of the projectable optical system are reduced.

Other features and advantages of the present application will become apparent from the following detailed description of exemplary embodiments thereof, which proceeds with reference to the accompanying drawings.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the application and together with the description, serve to explain the principles of the application.

Fig. 1 is a block diagram showing a projection optical system according to an embodiment of the present application.

Fig. 2 a-2 f show beam fans of projection optical systems according to embodiments of the present application.

Fig. 3 is a diagram illustrating a modulation transfer function of a projection optical system according to an embodiment of the present application.

Fig. 4 is a field curvature diagram of a projection optical system according to an embodiment of the present application.

Fig. 5 is a distortion diagram of a projection optical system according to an embodiment of the present application.

Fig. 6 is a schematic diagram of the lateral color of the projection optical system of the present embodiment at the image side.

Description of reference numerals:

1. a curved reflector;

2. a first lens group; 21. a second lens; 22. a third lens; 20. a fourth lens;

3. a second lens group; 30. a fifth lens; 31. a sixth lens; 32. a seventh lens; 33. an eighth lens; 38. a ninth lens; 39. a tenth lens; 40. an eleventh lens; 34. a twelfth lens; 35. a thirteenth lens; 36. a fourteenth lens; 37. a fifteenth lens element;

4. a diaphragm; 5. a galvanometer; 6. a prism; 7. a plate glass; 8. an image source.

Detailed Description

Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that: the relative arrangement of the components and steps, the numerical expressions, and numerical values set forth in these embodiments do not limit the scope of the present application unless specifically stated otherwise.

The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the application, its application, or uses.

Techniques and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail, but are intended to be considered a part of the specification where appropriate.

In all examples shown and discussed herein, any particular value should be construed as merely illustrative, and not limiting. Thus, other examples of the exemplary embodiments may have different values.

It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be discussed further in subsequent figures.

In a first aspect of embodiments of the present application, a projection optical system is provided. In this embodiment, the projection optical system is an ultra-short-focus projection lens. The projection optical system is applied to a projector or an illumination light machine.

Referring to fig. 1, the projection optical system includes, in order from the enlargement side to the reduction side: a curved reflector 1, a first lens group 2 and a second lens group 3.

The focal power of the first lens group 2 is negative, and the focal power of the second lens group 3 is positive.

The first lens group 2 includes a moving lens group movable along an optical axis. The moving lens group comprises a second lens 21 and a third lens 22, and the focal powers of the second lens 21 and the third lens 22 are opposite.

In other words, the projection optical system includes, in order from the enlargement side to the reduction side: a curved reflector 1, a first lens group 2 and a second lens group 3. The first lens group 2 is positioned at the light-emitting side of the second lens group 3, and the curved reflector 1 is positioned at the light-emitting side of the first lens group 2. The curved reflector 1 is used for receiving the light emitted by the first lens group 2 and projecting the light onto the screen through the curved reflector 1.

The curved mirror 1 serves as a first lens of the projection optical system. The curved reflector 1 is used for reducing the projection ratio and compensating the aberration, thereby improving the picture quality. In particular, the ultra-short focal length projection lens is designed to achieve the minimum throw ratio projection distance/screen width), the present embodiment utilizes reflection to reduce the projection distance. For example, the curved mirror may be a reflective convex mirror and a reflective concave mirror.

In this embodiment, the zoom projection lens further includes a prism 6, a plate glass 7, and an image source 8. In use, the second lens group 3 is located on the light-emitting side of the image source 8, and in the present embodiment, the flat glass 7 is configured to receive the light emitted from the image source 8, and the prism 6 is configured to receive the light emitted from the flat glass 7. The second lens group 3 is used for receiving the light emitted by the prism 6.

In the present embodiment, the image source 8 provides an image beam. The image source 8 is a reflective light modulator such as a Liquid Crystal On Silicon panel (LCoS panel) or a Digital Micromirror Device (DMD). In other embodiments, the image source 8 may be a transmissive light Modulator such as a transmissive Liquid Crystal Panel (transmissive Liquid Crystal Panel), an Electro-Optic Modulator (Electro-Optic Modulator), a Magneto-Optic Modulator (Magneto-Optic Modulator), or an Acousto-Optic Modulator (AOM). For example, the associated image source 8 uses the DMD of texas instruments. The embodiment of the present application does not limit the type and kind of the image source 8.

Specifically, the first lens group 2 is located on the light exit side of the second lens group 3. The first lens group 2 receives the light emitted from the second lens group 3. The first lens group 2 compensates for the picture quality.

The first lens group 2 includes a movable lens group movable along an optical axis. The movable lens group compensates the adjusted picture, and the movable lens group plays a focusing role. In use, after the distance between the projection optical system and the screen is changed, focusing can be carried out by moving the lens group, and then focusing imaging is realized, so that the picture quality is further adjusted.

In the present embodiment, the moving lens group includes the second lens 21 and the third lens 22. The second lens 21 and the third lens 22 have opposite optical powers. For example, the power of the second lens 21 is positive, and the power of the third lens 22 is negative; alternatively, the power of the second lens 21 is negative and the power of the third lens 22 is positive. In the present embodiment, referring to fig. 1, the power of the second lens 21 is positive, the surface of the second lens 21 closer to the magnification side is a convex surface, and the surface of the second lens 21 farther from the magnification side is a convex surface. The refractive power of the third lens 22 is negative, the surface of the third lens 22 adjacent to the second lens 21 is a concave surface, and the surface of the third lens 22 away from the second lens 21 is a concave surface.

In this embodiment, the compensation is performed on the picture by a group of moving lens groups. Compared with the prior art that focusing can be performed by moving 2-3 groups of components at the same time, in the embodiment, a group of moving lens groups is applied to the projection optical system, so that the complexity of the projection optical system can be reduced while focusing is realized, and the operation and use of a user are facilitated. On the other hand, the volume of the projection optical system is reduced, and the carrying is convenient for users.

In one embodiment, the projection optical system further includes a galvanometer 5, the galvanometer 5 is disposed on a light emitting side of the prism 6, and the galvanometer 5 projects the light to the second lens group 3.

In this embodiment, the galvanometer 5, in combination with an XPR technique of texas instrument research, causes the image source 8 to rapidly dither at a speed several times faster than the human vision to realize pixel replication, and finally to present the image 4 times as much as the native pixel to improve the pixel quality and the image resolution, for example, the image can be raised from the original 1080P to 4K.

In one embodiment, referring to fig. 1, the first lens group 2 further includes a fixed lens group located between the curved mirror 1 and the moving lens group; the fixed lens group comprises at least one fourth lens 20 with negative optical power.

In this embodiment, the fixed lens group is used to adjust the quality of the picture. After the projection optical system is assembled, the fixed lens group is fixed in the projection optical system.

Referring to fig. 1, the fixed lens group in this embodiment includes a fourth lens 20, and the fourth lens 20 has negative power. The surface of the fourth lens 20 adjacent to the curved reflector 1 is a concave surface, and the surface of the fourth lens 20 adjacent to the second lens 21 is a concave surface.

In the present embodiment, the moving lens group is located between the fixed lens group and the second lens group 3, the distance between the fixed lens group and the second lens group 3 is not changed, and the moving lens group moves back and forth between the fixed lens group and the second lens group 3. The moving lens cluster can be used at different focus sizes (80 "-120") to compensate for the picture.

In this embodiment, the lens arrangement is very sensitive in the ultra-short-focus projection lens application field. The fixed lens group is positioned between the curved reflector 1 and the movable lens group, and the image quality is maintained through the matching of the fixed lens group and the movable lens group. In the first lens group, if the positions of the fixed lens group and the movable lens group are changed, the image quality is adversely affected.

In one embodiment, the diopter range of the curved mirror 1 is: 25-35; the diopter range of the first lens group 2 is as follows: -200 to-400; the range of the dioptric power of the second lens group 3 is: 10.5 to 12.5.

In this embodiment, the diopter of the curved surface mirror 1, the diopter of the first lens group 2, and the diopter of the second lens group 3 are defined, and the optical quality of the projection optical system can be improved.

For example, the refractive power of the first lens 1 is defined as 27.93, the refractive power of the first lens group is defined as-306.74, and the refractive power of the second lens group is defined as 11.77, so that the effective focal length of the projection optical system is 2.033, the field angle of the projection optical system is 155.9 ° (ultra-wide angle is realized), the projection ratio of the projection optical system is 0.21, and the image-side telecentric CRA angle is less than 1 °. The image generated by the projection optical system has the characteristics of high quality, high stability and low distortion.

In one embodiment, referring to fig. 1, the second lens group includes: a diaphragm 4, fifth and

sixth lenses

30, 31 located on a first side of the diaphragm 4, seventh and

eighth lenses

32, 33 located on a second side of the diaphragm 4, and at least two sets of cemented lenses located between the seventh and

eighth lenses

32, 33; the first side is opposite to the second side, and the first side is closer to the first lens group 2;

the fifth lens 30 and the sixth lens 31 are both aspheric lenses.

The eighth lens 33 is located farther from the stop 4 than the seventh lens 32, and the eighth lens 33 is an aspherical lens.

In the present embodiment, the second lens group 3 is used to adjust the quality of a picture. When the projection optical system is assembled, the second lens group 3 is fixed inside the projection optical system.

In this embodiment, the second lens group 3 can ensure uniformity of an image screen. For example, with the diaphragm 4 of f1.7, the amount of light entering the diaphragm 4 is larger, and the luminance of the imaged picture is higher.

In this embodiment, the fifth lens 30 and the sixth lens 31 are located on the front side of the diaphragm 4, and the seventh lens 32 and the eighth lens 33 are located on the rear side of the diaphragm 4. That is, the fifth lens 30 and the sixth lens 31 are located on the diaphragm 4 side and are disposed near the enlargement side; the seventh lens 32 and the eighth lens 33 are located on the other side of the diaphragm 4 and are disposed away from the magnification side.

In this embodiment, the fifth lens 30, the sixth lens 31, and the eighth lens 33 are all aspherical lenses. Specifically, the more aspheric lenses can obtain better picture quality in terms of design, but the more aspheric lenses are assembled, the more sensitive to assembly tolerances, and therefore, the fifth lens 30, the sixth lens 31 and the eighth lens 33 are all aspheric lenses in terms of balancing picture quality and mass productivity in design.

In this embodiment, when the fifth lens element 30, the sixth lens element 31 and the eighth lens element 33 are used in combination, the edge high-angle spherical aberration and aberration can be reduced, thereby improving the picture quality.

In the present embodiment, at least two groups of cemented lenses are disposed between the seventh lens 32 and the eighth lens 33, so that the image quality is improved by reducing the chromatic aberration and the image sensitivity of the image through the two groups of cemented lenses, compared with the prior art in which one group of cemented lenses is disposed in the projection optical system.

In this embodiment, the second lens group 3 includes two aspherical lenses located at the stop 4, one aspherical lens located at the rear side of the stop 4, and the aspherical lens located at the rear side of the stop 4 is disposed closer to the image source 8. Meanwhile, at least two sets of cemented lenses are disposed between the seventh lens 32 and the eighth lens 33 located on the rear side of the diaphragm 4. By arranging and combining the fifth lens 30, the sixth lens 31, the seventh lens 32, and the eighth lens 33, and the two groups of cemented lenses located between the seventh lens 32 and the eighth lens 33, the projection optical system can reduce the projection ratio on one hand, achieve ultra-short-focus projection, and further improve the picture quality on the other hand.

In one embodiment, as shown with reference to FIG. 1, the optical powers of the fifth lens 30 and the sixth lens 31 are opposite.

In this embodiment, the fifth lens 30 and the sixth lens 31 are located on the front side of the diaphragm 4. In use, the fifth lens element 30 and the sixth lens element 31 are disposed away from the image source 8. The present embodiment defines that the optical powers of the fifth lens 30 and the sixth lens 31 are opposite. That is, the focal power of the fifth lens 30 is positive, and the focal power of the sixth lens 31 is negative; or the focal power of the fifth lens 30 is negative and the focal power of the sixth lens 31 is positive.

Referring to fig. 1, the power of the fifth lens 30 is negative, the surface of the fifth lens 30 closer to the magnification side is convex, and the surface of the fifth lens 30 farther from the magnification side is concave. The refractive power of the sixth lens 31 is positive, the surface of the sixth lens 31 closer to the magnification side is a convex surface, and the surface of the sixth lens 31 farther from the magnification side is a flat surface.

If a lens is arranged in front of the diaphragm 4, the image formed at high temperature is easier to be blurred (defocused), and the image quality is reduced. When the sixth lens 31 and the fifth lens 30 with opposite optical powers are used in cooperation, the positive diopter and the negative diopter are balanced to reduce the influence of temperature on the fifth lens 30 and the sixth lens 31.

In one embodiment, the refractive index Nd < 1.7 of the fifth lens 30; the refractive index Nd of the sixth lens 31 is less than 1.7.

Specifically, the refractive index range of the fifth lens 30 is: 1.48-1.7; the refractive index range of the sixth lens 31 is: 1.48-1.7. In this embodiment, the refractive indexes of the fifth lens 30 and the sixth lens 31 are limited, and the fifth lens 30 and the sixth lens 31 may be plastic lenses or glass lenses.

Referring to fig. 1, the image source 8 generates heat during operation. The fifth lens 30 and the sixth lens 31 are disposed away from the image source 8 and the seventh lens 32 and the eighth lens 33 are disposed proximate to the image source 8. Namely, the fifth lens 30 and the sixth lens 31 are disposed at positions far away from the heating area, and the aspheric lens disposed far away from the heating area is made of plastic, so that the deformation influence of heat on the lens (the plastic material is sensitive to temperature) can be reduced, and the production cost of the product can be reduced. The lens arranged close to the heating area is made of glass materials, so that the influence of heat on the deformation of the lens can be reduced.

In one embodiment, referring to fig. 1, the seventh lens 32 is an aspheric lens.

In this embodiment, the fifth lens 30 and the sixth lens 31 located in front of the stop 4 are both aspheric lenses, and the seventh lens 32 and the eighth lens 33 defined in back of the stop 4 are both aspheric lenses, which can further reduce edge high-angle spherical aberration and aberration, thereby further improving picture quality.

In one embodiment, referring to fig. 1, a twelfth lens 34, a thirteenth lens 35, a fourteenth lens 36 and a fifteenth lens 37 are sequentially disposed between the seventh lens 32 and the eighth lens 33; the two groups of cemented lenses include a first cemented lens and a second cemented lens;

the twelfth lens 34 and the thirteenth lens 35 are connected by gluing to form a first cemented lens; the fourteenth lens 36 and the fifteenth lens 37 are cemented together to form a second cemented lens.

Specifically, the twelfth lens 34 and the thirteenth lens 35 are cemented to form a first cemented lens. The fourteenth lens 36 and the fifteenth lens 37 are cemented to form a second cemented lens. The chromatic aberration is further reduced and the sensitivity is reduced through the first cemented lens and the second cemented lens, and the picture quality is improved.

In a specific embodiment, the twelfth lens 34 and the thirteenth lens 35 may be spherical lenses, and the twelfth lens 34 and the thirteenth lens 35 are cemented, so that on one hand, the picture quality can be improved; on the other hand, the manufacturing is convenient, and the manufacturing cost is reduced.

In a specific embodiment, the fourteenth lens 36 and the fifteenth lens 37 can be spherical lenses, and the fourteenth lens 36 and the fifteenth lens 37 are cemented, so that on one hand, the picture quality can be improved; on the other hand, the manufacturing is convenient, and the manufacturing cost is reduced.

In one embodiment, referring to FIG. 1, the optical powers of the twelfth lens 34 and the thirteenth lens 35 are opposite. The fourteenth lens 36 has an optical power opposite to that of the fifteenth lens 37.

Specifically, the power of the twelfth lens 34 is positive, and the power of the thirteenth lens 35 is negative. Or the power of the twelfth lens 34 is negative and the power of the thirteenth lens 35 is positive. The power of the fourteenth lens 36 is positive, and the power of the fifteenth lens 37 is negative. The power of the fourteenth lens 36 is negative, and the power of the fifteenth lens 37 is positive.

Referring to fig. 1, the twelfth lens 34 has positive refractive power, a surface of the twelfth lens 34 adjacent to the seventh lens is a concave surface, and a surface of the twelfth lens 34 away from the seventh lens is a convex surface. The thirteenth lens 35 has a negative refractive power, a surface of the thirteenth lens 35 adjacent to the twelfth lens 34 is a concave surface, and a surface of the thirteenth lens 35 distant from the twelfth lens 34 is a convex surface.

The fourteenth lens 36 has positive refractive power, a surface of the fourteenth lens 36 close to the thirteenth lens is a convex surface, and a surface of the fourteenth lens 36 far from the thirteenth lens 35 is a convex surface. The fifteenth lens 37 has negative refractive power, a surface of the fifteenth lens 37 close to the fourteenth lens 36 is a concave surface, and a surface of the fifteenth lens 37 far from the fourteenth lens 36 is a convex surface.

In this embodiment, by the cooperative use of the twelfth lens 34, the thirteenth lens 35, the fourteenth lens 36, and the fifteenth lens 37, the picture quality is maintained.

In this embodiment, the second lens group 3 includes, in order from the magnification side to the reduction side: a ninth lens 38, a tenth lens 39, a fifth lens 30, a sixth lens 31, an eleventh lens 40, a seventh lens 32, a twelfth lens 34, a thirteenth lens 35, a fourteenth lens 36, a fifteenth lens 37, and an eighth lens 33, wherein a stop 4 is disposed between the eleventh lens 40 and the seventh lens 32;

the focal power of the second lens group 3 is ordered as follows: positive negative plus/negative positive plus.

In this embodiment, the power of the lenses in the second lens group is defined so that the power distribution of the lenses in the second lens group 3 is uniform, and the distortion characteristics of the imaged picture can be restored.

Further, the first lens group 2 includes, in order from the magnification side to the reduction side, a fourth lens 20, a second lens 21, and a third lens 22. The power of the first lens group 2 is ordered negative positive and negative.

The second lens 21 and the third lens 22 are movable lens groups, the second lens 21 and the third lens 22 can move back and forth along the optical axis, the focal length of the whole lens group can be adjusted by moving the position of the movable lens group, and then a user can conveniently adjust the definition of the image with different projection sizes so as to ensure the projection effect of the image.

In one embodiment, referring to fig. 1, the fifth lens 30, the sixth lens 31, and the eighth lens 33 are all aspheric lenses. The embodiment can reduce the edge large-angle spherical aberration and aberration, thereby improving the picture quality.

In one embodiment, referring to fig. 1, the twelfth lens 34 is cemented with the thirteenth lens 35 to form a first cemented lens; the twelfth lens 34 is cemented with the thirteenth lens 35 to form a second cemented lens. In the present embodiment, the two groups of cemented lenses reduce the chromatic aberration and the sensitivity of the image, so as to improve the image quality.

In one embodiment, and as shown with reference to FIG. 1, the curved mirror is a concave mirror.

Specifically, the curved mirror may be a convex mirror or a concave mirror. In this embodiment, it is considered that the convex mirror is large in size and has an exposed outer surface that is prone to dust accumulation. In this embodiment, the curved reflecting mirror is a concave mirror.

In this embodiment, the convex reflector diffuses light and the concave reflector converges light. The smaller the focal length of the concave reflector is, the stronger the convergence capability of the concave reflector to light rays is, and the higher the image imaging quality is.

In one embodiment, referring to fig. 1, the second lens 21 and the third lens 22 are cemented to form a third cemented lens.

In this embodiment, the second lens 21 is a spherical lens, the third lens 22 is a spherical lens, and the second lens 21 and the third lens 22 are cemented together to form a third cemented lens, so as to reduce the focal length of the projection optical system, improve the magnification of the projection optical system, correct paraxial spherical aberration, correct chromatic aberration, and improve the picture quality.

According to a second aspect of the embodiments of the present application, an electronic device is provided. The projection optical system according to the first aspect of the electronic device. In this embodiment, the electronic device is a projection device. For example, the projection device may be a projector, or an illumination light engine, etc.

In a specific embodiment, referring to fig. 1, the projection optical system includes a curved mirror 1, a fourth lens 20, a second lens 21, a third lens 22, a ninth lens 38, a tenth lens 39, a fifth lens 30, a sixth lens 31, an eleventh lens 40, a seventh lens 32, a twelfth lens 34, a thirteenth lens 35, a fourteenth lens 36, a fifteenth lens 37, and an eighth lens 33, and a stop 4 is disposed between the eleventh lens 40 and the seventh lens 32; the power arrangement order of the projection optical system is: the aspheric concave mirror (+), the object side surface of the negative positive/negative positive curved mirror, for example, is S1, the image side surface (the surface close to the magnification side) of the fourth lens 20 is S2, the object side surface (the surface far from the magnification side) is S3, the image side surface of the second lens 21 is S4, the object side surface is S5.

Other specific parameters of each lens and the diaphragm 4 are shown in the following table 1:

table 1:

in the present embodiment, the curved mirror 1 (surface S1) is an aspherical lens, the fifth lens 30 (surfaces S11 and S12) is an aspherical lens, the sixth lens 31 (surfaces S13 and S14) is an aspherical lens, the seventh lens 32 (surfaces S18 and S19) is an aspherical lens, the eighth lens 33 (surfaces S27 and S28) is an aspherical lens, and the remaining lenses are spherical lenses. The spherical parameters corresponding to the aspherical lens are shown in table 2:

table 2:

in the present embodiment, the first lens group 2 includes a fixed lens group, which is the fourth lens 20 (the object side surface is S3), and a moving lens group, which includes the second lens 21 and the third lens 22 (the object side surface is S6). In the embodiment, the projection optical system realizes focusing by moving the lens group, wherein the focusing size is 80-120 ".

Referring to fig. 1, the moving lens group moves back and forth between the fixed lens group and the second lens group 3, corresponding to different size focusing parameters. Wherein the distance between the fixed lens group and the second lens group 3 is fixed. Wherein the different size focusing parameters are shown in table 3:

table 3:

where 6.24 indicates that the distance between the surface S3 and the image-side surface S4 of the fourth lens 20 is 6.24mm at a focusing size of 100 ". 9.46 indicates that the distance between the surface S6 and the image-side surface S7 of the ninth lens 9 is 9.46mm at a focusing size of 100 ".

From the above parameters, the effective focal length of the projection optical system was 2.033, the projection ratio was 0.21, and the field angle was 155.6 °. The obtained parameters of the fields of view of the optical imaging module are shown in fig. 2a to 6.

Fig. 2a to 2e are beam fan diagrams of the projection optical system. Please refer to fig. 2a to fig. 2 e. FIGS. 2a to 2e are diagrams of beam fans (Transverse ray fan plots) of the projection optical system at different image heights, in which the maximum scale and the minimum scale of the EX, EY, PX, and PY axes are +50 micrometers (μm) and-50 micrometers (along the horizontal axis, one grid represents 10 micrometers), respectively. The graphs shown in fig. 2a to 2e are all within the standard range, so that it can be verified that the projection optical system of the present embodiment can achieve good optical imaging quality.

Fig. 3 shows a Modulation Transfer Function (MTF) diagram according to the present embodiment. Fig. 3 is a diagram of the modulation transfer function of the projection optical system at different image heights. Wherein the transverse axis is the Spatial Frequency in cycles per mm and the longitudinal axis is the OTF Modulus (modules of the OTF). The numerical value marked by "TS" represents image height. As can be seen from the figure, the OTF mode value of the image can be always maintained at 0.7 or more in the interval of 0mm to 93mm in spatial frequency, and generally, the quality of the image is higher as the OTF mode value approaches 1, but due to the influence of various factors, the OTF mode value is not 1, and generally, when the OTF mode value can be maintained at 0.7 or more, it means that the image has high imaging quality, and the sharpness of the screen is excellent, so it can be seen that the ultra-short-focus projection optical system of the present embodiment has higher imaging quality.

FIG. 4 is a Field Curvature (Field Curvature) diagram of the present embodiment. As can be seen from the figure, the curvature of field value of the projection optical system is less than 0.05, and it can be seen that the projection optical system of this embodiment can correct the curvature of field.

As shown in fig. 5, it is a diagram of Distortion (Distortion) values of the projection optical system, and it can be seen from the diagram that the Distortion values of the projection optical system are all less than 0.5% (usually less than < 1%), and it can be seen that the Distortion after imaging by the system under each field of view is also smaller, which can fully satisfy the requirement of human eyes on Distortion.

Fig. 6 is a Lateral Color (lareral Color) diagram on the image side of the projection optical system of the present embodiment, and the numerical values thereof are shown in table 6. The difference in lateral color is smaller than one pixel, thereby avoiding the problem of color error when projecting color light, which means that the projection optical system of the present embodiment also effectively corrects chromatic aberration.

According to the example, the distortion which can be achieved by the optical imaging module is less than 1%; the MTF of the full field of view is more than 50% @93 lp/mm; the image-side telecentric CRA angle is less than 1 deg., and the total system length is only 8.5 mm. Therefore, the optical imaging module provided by the application can further improve the imaging quality on the premise of ensuring the optical performance of the optical imaging module.

In the above embodiments, the differences between the embodiments are mainly described, and different optimization features between the embodiments can be combined to form a better embodiment as long as they are not contradictory, and further description is omitted here in view of brevity of the text.

Although some specific embodiments of the present application have been described in detail by way of illustration, it should be understood by those skilled in the art that the above illustration is only for purposes of illustration and is not intended to limit the scope of the present application. It will be appreciated by those skilled in the art that modifications may be made to the above embodiments without departing from the scope and spirit of the present application. The scope of the application is defined by the appended claims.

Claims

1. A projection optical system characterized by comprising, in order from an enlargement side to a reduction side: the lens comprises a curved surface reflector (1), a first lens group (2) and a second lens group (3);

the focal power of the first lens group (2) is negative, and the focal power of the second lens group (3) is positive;

the first lens group (2) comprises a movable lens group which can move along an optical axis;

the moving lens group comprises a second lens (21) and a third lens (22), and the optical powers of the second lens (21) and the third lens (22) are opposite.

2. The projection optical system according to claim 1, characterized in that the first lens group further comprises a fixed lens group located between the curved mirror (1) and the moving lens group;

the fixed lens group comprises at least one fourth lens (20) with negative focal power.

3. The projection optical system according to claim 1, wherein the second lens group comprises: -a diaphragm (4), -fifth (30) and sixth (31) lenses located on a first side of the diaphragm (4), -seventh (32) and eighth (33) lenses located on a second side of the diaphragm (4), and-at least two groups of cemented lenses located between the seventh (32) and eighth (33) lenses; the first side is opposite to the second side, and the first side is closer to the first lens group (2);

the fifth lens (30) and the sixth lens (31) are both aspheric lenses;

the eighth lens (33) is located farther from the diaphragm (4) than the seventh lens (32), and the eighth lens (33) is an aspherical lens.

4. The projection optical system according to claim 3, characterized in that the optical powers of the fifth lens (30) and the sixth lens (31) are opposite.

5. The projection optical system according to claim 3, characterized in that the refractive index Nd < 1.7 of the fifth lens (30);

the refractive index Nd of the sixth lens (31) is less than 1.7.

6. The projection optical system according to claim 3, characterized in that the seventh lens (32) is an aspherical lens.

7. The projection optical system according to claim 3, characterized in that a twelfth lens (34), a thirteenth lens (35), a fourteenth lens (36), and a fifteenth lens (37) are disposed in this order between the seventh lens (32) and the eighth lens (33); the two groups of cemented lenses include a first cemented lens and a second cemented lens;

the twelfth lens (34) and the thirteenth lens (35) are in cemented connection to form a first cemented lens;

the fourteenth lens (36) and the fifteenth lens (37) are cemented together to form a second cemented lens.

8. The projection optical system according to claim 7,

the optical powers of the twelfth lens (34) and the thirteenth lens (35) are opposite;

the fourteenth lens (36) has an optical power opposite to that of the fifteenth lens (37).

9. The projection optical system according to claim 1, wherein the second lens group (3) comprises, in order from an enlargement side to a reduction side: a ninth lens (38), a tenth lens (39), a fifth lens (30), a sixth lens (31), an eleventh lens (40), a seventh lens (32), a twelfth lens (34), a thirteenth lens (35), a fourteenth lens (36), a fifteenth lens (37), and an eighth lens (33), wherein a diaphragm (4) is provided between the eleventh lens (40) and the seventh lens (32);

the focal power of the second lens group (3) is ordered as follows: positive negative plus/negative positive plus.

10. The projection optical system according to claim 9, characterized in that the fifth lens (30), the sixth lens (31), and the eighth lens (33) are all aspherical lenses.

11. The projection optical system according to claim 9, characterized in that the twelfth lens (34) is cemented with the thirteenth lens (35) to form a first cemented lens;

12. The projection optical system according to claim 1, characterized in that the curved mirror (1) is a concave mirror.

13. The projection optical system according to claim 1, characterized in that the second lens (21) and the third lens (22) are cemented together to form a third cemented lens.

14. An electronic device characterized in that it comprises the projection optical system according to any one of claims 1 to 13.