Projection lens and projection display equipment
By designing a projection lens with a combination of positive and negative power and a projection lens with a turning prism, the problem of difficulty in miniaturizing the DLP projection lens design in AR technology is solved, and high-quality AR projection effect is achieved.
Patent Information
- Application Number
- CN202421142721.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-05-23
- Publication Date
- 2024-12-24
- Estimated Expiration
- 2034-05-23
AI Technical Summary
At this stage, the projection lens design of DLP technology in AR technology is difficult to meet the needs of AR miniaturization and lightweightness, especially when the size of the luminous chip is reduced, the lens design faces challenges.
A projection lens is designed, including a diaphragm, a first lens, a second lens, a third lens and a fourth lens. The first lens and the fourth lens are aspherical lenses with positive power, and the second lens and the third lens are A spherical lens with negative power forms an adhesive lens, combined with a turning prism, optimizes the focal length and air gap of the lens, and reduces the difficulty of lens production and assembly.
Effectively reduce the chromatic aberration and aberration of the lens, improve projection quality, and is suitable for the smallest chip in DLP technology, achieving miniaturization and high-quality projection effects.
Smart Images
Figure CN222232763U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of optical imaging, in particular to a projection lens and a projection display device. Background Art
[0002] The AR technology is developing faster and faster. For end users, the miniaturization and light weight of color imaging AR are essential attributes. At present, the DLP AR technology is an important one among various AR technical paths. With the improvement of chip technology, the size of the light-emitting chip can be made smaller and smaller, and the design challenges of the corresponding projection lens are also getting higher and higher. Summary of the Utility Model
[0003] One technical problem to be solved by the utility model is to provide a projection lens to adapt to the development of AR miniaturization.
[0004] To solve the above technical problem, the technical solution of the utility model is: a projection lens is successively provided with a diaphragm, a first lens, a second lens, a third lens and a fourth lens. Both the first lens and the fourth lens have positive optical power, and both the second lens and the third lens have negative optical power; the second lens and the third lens form a cemented lens.
[0005] As a preferred technical solution, the first lens and the fourth lens are aspherical lenses, and the second lens and the third lens are spherical lenses.
[0006] As a preferred technical solution, the first lens is a meniscus aspherical lens, the second lens and the third lens are meniscus spherical lenses, and the fourth lens is a biconvex aspherical lens.
[0007] As a preferred technical solution, the first lens, the second lens, the third lens and the fourth lens are all glass lenses.
[0008] As a preferred technical solution, a turning prism is arranged on one side of the fourth lens away from the third lens.
[0009] As a preferred technical solution, the turning prism is a right-angle prism.
[0010] As a preferred technical solution, the total focal length of the projection lens is 5mm < f < 10mm.
[0011] As a preferred technical solution, the focal length of the first lens is 5 < f1 < 15; the focal length of the second lens is -10 < f2 < -1; the focal length of the third lens is 2 < f3 < 10; the focal length of the fourth lens is 5 < f4 < 15.
[0012] As a preferred technical solution, the ratio of the middle thickness of the first lens to the total optical length of the projection lens is 0.1<T1 / total length<0.3;
[0013] The ratio of the middle thickness of the second lens to the total optical length of the projection lens is 0.04<T2 / total length<0.2;
[0014] The ratio of the middle thickness of the third lens to the total optical length of the projection lens is 0.1<T3 / total length<0.3;
[0015] The ratio of the middle thickness of the fourth lens to the total optical length of the projection lens is 0.1<T4 / total length<0.3.
[0016] As a preferred technical solution, the ratio of the air gap between the first lens and the second lens to the total optical length of the projection lens is 0.1≤Air1 / total length<0.3; the ratio of the air gap between the third lens and the fourth lens to the total optical length of the projection lens is 0.001≤Air3 / total length<0.1.
[0017] As a preferred technical solution, the ratio of the air gap between the aperture and the first lens to the total optical length of the projection lens is 0≤Air aperture / total length<0.1.
[0018] As a preferred technical solution, the ratio of the air gap between the fourth lens and the turning prism to the total optical length of the projection lens is 0.01≤Air4 / total length<0.15.
[0019] As a preferred technical solution, in the direction opposite to the optical path, the two curvature radii of the first lens are 2<R 11 <10 and 5<R 12 <30; the two curvature radii of the second lens are respectively -10<R 21 <10 and -200<R 22 <50; the two curvature radii of the third lens are respectively -200<R 31 <50 and -15<R 32 <-2; the two curvature radii of the fourth lens are 5<R 41 <36 and -20<R 42 <-4.
[0020] Due to the adoption of the above technical solution, a projection lens is provided with an aperture, a first lens, a second lens, a third lens and a fourth lens in sequence, the first lens and the fourth lens both have positive optical focal length, the second lens and the third lens both have negative optical focal length; the second lens and the third lens form a cemented lens; the second lens and the third lens are combined into a cemented lens, which can effectively reduce the chromatic aberration of the lens and improve the projection quality.
[0021] The first lens and the fourth lens adopt aspherical lenses, which can effectively reduce lens aberrations such as spherical aberration and coma; the second lens and the third lens adopt spherical lenses, which can effectively reduce the difficulty of the bonding process of the bonding surface of the second lens and the third lens, and facilitate mass production.
[0022] Another technical problem to be solved by the utility model is to provide a projection lens based on the above.
[0023] In order to solve the above technical problems, the technical solution of the utility model is: a projection display device, including the projection lens mentioned above, and also including a spatial light modulator and a projection light source.
[0024] This projection display device adopts the projection lens described above, which can be matched with the smallest chip in DLP technology - 0.16-inch DMD, with small lens chromatic aberration and high projection quality. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] The following drawings are only intended to illustrate and explain the present invention, and do not limit the scope of the present invention.
[0026] Figure 1 It is a schematic diagram of the structure of the first embodiment of the present utility model;
[0027] Figure 2 This is a light path diagram of the first embodiment of the utility model;
[0028] Figure 3 This is an optical distortion diagram of the first embodiment of the utility model;
[0029] Figure 4 It is the MTF diagram of the first embodiment of the utility model;
[0030] Figure 5 This is the through-focus MTF diagram of the first embodiment of the utility model;
[0031] Figure 6 It is a relative illumination diagram of the first embodiment of the utility model;
[0032] Figure 7 This is the optical path diagram of the second embodiment of the utility model;
[0033] Figure 8This is an optical distortion diagram of the second embodiment of the utility model;
[0034] Fig. 9 It is the MTF diagram of the second embodiment of the utility model;
[0035] Fig.10 This is the through-focus MTF diagram of the second embodiment of the present utility model;
[0036] Fig.11 It is a relative illumination diagram of the second embodiment of the utility model;
[0037] Fig.12 This is the optical path diagram of the third embodiment of the utility model;
[0038] Fig.13 This is an optical distortion diagram of the third embodiment of the present utility model;
[0039] Fig.14 This is the MTF diagram of the third embodiment of the present utility model;
[0040] Fig.15 This is the through-focus MTF diagram of the third embodiment of the present utility model;
[0041] Fig.16 It is a relative illumination diagram of the third embodiment of the present utility model;
[0042] In the figure: 1-first lens; 2-second lens; 3-third lens; 4-fourth lens; 5-aperture; 6-turn prism; 7-spatial light modulator. DETAILED DESCRIPTION
[0043] The present invention is further described below in conjunction with the accompanying drawings and examples. In the following detailed description, only certain exemplary embodiments of the present invention are described by way of illustration. Needless to say, those skilled in the art will recognize that the described embodiments may be modified in various ways without departing from the spirit and scope of the present invention. Therefore, the drawings and descriptions are illustrative in nature and are not intended to limit the scope of protection of the claims.
[0044] like Figure 1 and Figure 2 As shown, a projection lens is provided with an aperture 5, a first lens 1, a second lens 2, a third lens 3 and a fourth lens 4 in sequence against the light path, the first lens 1 and the fourth lens 4 are aspherical lenses with positive optical power, the second lens 2 and the third lens 3 are spherical lenses with negative optical power; the second lens 2 and the third lens 3 form a cemented lens, that is, the air gap between the second lens 2 and the third lens 3 is 0.
[0045] The first lens 1 and the fourth lens 4 are aspherical lenses, which can effectively reduce aberrations such as spherical aberration and coma of the lens; the second lens 2 and the third lens 3 are combined into a cemented lens, which can effectively reduce the chromatic aberration of the lens; and both the second lens 2 and the third lens 3 are spherical lenses, effectively reducing the cementing process difficulty of the cemented surface of the second lens 2 and the third lens 3, which is helpful for mass production.
[0046] The first lens 1 is a meniscus aspherical lens, the second lens 2 and the third lens 3 are meniscus spherical lenses, and the fourth lens 4 is a biconvex aspherical lens. The first lens 1, the second lens 2, the third lens 3 and the fourth lens 4 are all glass lenses. All four lenses use glass lenses, which have high reliability and low risk of thermal defocus;
[0047] Against the optical path, a turning prism 6 is provided on the rear side of the fourth lens 4 (i.e., the side away from the third lens 3). The turning prism 6 is preferably a right-angle prism, one right-angle surface of the right-angle prism faces the fourth lens 4, and the other right-angle surface of the right-angle prism faces the spatial light modulator 7. This projection lens adopts an inverse optical path design, and the optical path diagram is as Figure 2 shown.
[0048] The total focal length of the projection lens is 5mm < f < 10mm; the focal length of the first lens 1 is 5 < f1 < 15; the focal length of the second lens 2 is -10 < f2 < -1; the focal length of the third lens 3 is 2 < f3 < 10; the focal length of the fourth lens 4 is 5 < f4 < 15, and the unit of the above focal lengths is mm. Based on the above characteristics, the optical power distribution of the projection lens is uniform, making the tolerance sensitivity of each lens lower, improving the lens yield, and facilitating mass production.
[0049] The ratio of the center thickness of the first lens 1 to the optical total length of the projection lens is 0.1 < T1 / total length < 0.3; the ratio of the center thickness of the second lens 2 to the optical total length of the projection lens is 0.04 < T2 / total length < 0.2; the ratio of the center thickness of the third lens 3 to the optical total length of the projection lens is 0.1 < T3 / total length < 0.3; the ratio of the center thickness of the fourth lens 4 to the optical total length of the projection lens is 0.1 < T4 / total length < 0.3. The projection lens includes the aperture stop 5, the first lens 1, the second lens 2, the third lens 3, the fourth lens 4 and the turning prism 6 described above, and the optical total length is determined based on the projection lens with the above structure. Based on the above technical characteristics, it has the following advantages: ① It is beneficial to reduce the manufacturing process difficulty of the lens; ② It is beneficial to save raw materials and reduce costs; ③ It has a small size and a compact structure, which is beneficial to the miniaturization of the optical engine;
[0050] The ratio of the air gap between the first lens 1 and the second lens 2 to the total optical length of the projection lens is 0.1≤Air1 / total length<0.3; the air gap between the second lens 2 and the third lens 3 is 0; the ratio of the air gap between the third lens 3 and the fourth lens 4 to the total optical length of the projection lens is 0.001≤Air3 / total length<0.1. The ratio of the air gap between the aperture 5 and the first lens 1 to the total optical length of the projection lens is 0≤Air aperture 5 / total length<0.1. The ratio of the air gap between the fourth lens 4 and the turning prism 6 to the total optical length of the projection lens is 0.01≤Air4 / total length<0.15. Based on the above features, the following beneficial effects are achieved: ① When the air gap between the aperture 5 and the first lens 1 is 0, the purpose of the invention can also be achieved; however, the air gap between the aperture 5 and the first lens 1 is preferably greater than 0. When the air gap behind the aperture 5 (i.e., Air aperture 5) is greater than 0, a gap is reserved for the optical machine and waveguide assembly, which is convenient for the implementation of the AA process; ② The air gap before and after the fourth lens 4 is constrained according to the above parameters to ensure that a certain air gap is reserved between the fourth lens 4 and the turning prism 6, so as to facilitate the assembly and debugging of the lens; ③ It is beneficial to the lens structure design, convenient for lens assembly, and realizes mass production.
[0051] In the direction opposite to the optical path, the two curvature radii of the first lens 1 are 2<R 11 <10 and 5<R 12 <30; the two curvature radii of the second lens 2 are respectively -10<R 21 <10 and -200<R 22 <50; the two curvature radii of the third lens 3 are respectively -200<R 31 <50 and -15<R 32 <-2; the two curvature radii of the fourth lens 4 are 5<R 41 <36 and -20<R 42 <-4; the unit of the above radius of curvature is mm. Based on the above features, the following beneficial effects are achieved: ① It is helpful to reduce the difficulty of lens manufacturing process; ② It is helpful to reduce the tolerance sensitivity of the lens and improve the yield rate of lens assembly.
[0052] Based on the projection lens structure described above, the following index parameters of the projection lens can be achieved:
[0053] ①20°≤FOV≤40°;
[0054] ②2mm≤image height≤4mm;
[0055] ③Matching resolution ≤93lp / mm;
[0056] Suitable for visible light sources in the range of 420nm to 680nm.
[0057] This projection lens is used in the field of AR projection and is matched with the smallest chip in DLP technology - 0.16-inch DMD. It has small lens chromatic aberration and high projection quality.
[0058] Embodiment 1:
[0059] The total optical length of the projection lens is 12.5 mm; F number = 1.8; EFFL = 7.8 mm; FOV 28°.
[0060] The specific parameters of the projection lens of this embodiment are shown in Table 1 below, which includes parameters such as the curvature radius, thickness, glass material, and semi-diameter of the lens. The aperture size is pupil=4.35mm, and the pupil distance is pupil distance=0.2mm. The selection of the pupil distance facilitates the friendly matching of the optical machine and the waveguide.
[0061] Table 1:
[0062]
[0063]
[0064] The optical architecture and optical path diagram of this embodiment are shown in Figure 1 and Figure 2 As shown, the optical distortion diagram of this embodiment is as shown in Figure 3 As shown, the optical distortion is less than 0.2%, which is conducive to high-quality restoration of 3D printing; the MTF diagram of this embodiment is as follows Figure 4 As shown, the average MTF of each field of view is greater than 0.53, and the imaging is good; the defocus MTF diagram of this embodiment is as follows Figure 5 As shown, the defocus range of MTF>0.3 is greater than 0.027mm, which has a larger defocus range and better stability; the relative illumination diagram of this embodiment is as shown Figure 6 As shown, the relative illumination at the edge is greater than 80% of the center, indicating that the image brightness of the lens of the invention is uniform, the light energy loss at the edge is small, and the utilization rate of the illumination light is high.
[0065] Embodiment 2:
[0066] The total optical length of the projection lens is 12.2 mm and the FOV is 28°.
[0067] Specific parameters of the projection lens of this embodiment are shown in Table 2 below, where the aperture size is pupil=4.35 mm, and the exit pupil distance is pupil distance=0.2 mm.
[0068] Table 2:
[0069]
[0070]
[0071] The optical path diagram of this embodiment is as follows Figure 7 As shown, the MTF diagram, optical distortion diagram, defocus MTF diagram, and relative illumination diagram of this embodiment are shown in FIG. Figures 8 to 11 As shown, the MTF, distortion, through-focus MTF, and relative illumination of this embodiment all meet the imaging requirements of the projection lens.
[0072] Embodiment three:
[0073] The total optical length of the projection lens is 13.5 mm and the FOV is 28°.
[0074] The specific parameters of the projection lens of this embodiment are shown in Table 3 below, where the aperture size is pupil=4.35 mm, and the exit pupil distance is pupil distance=0.2 mm.
[0075] Table 3:
[0076]
[0077]
[0078] The optical path diagram of this embodiment is as follows Fig.12 As shown, the MTF diagram, optical distortion diagram, defocus MTF diagram, and relative illumination diagram of this embodiment are shown in FIG. Figures 13 to 16 As shown, the MTF, distortion, through-focus MTF, and relative illumination of this embodiment all meet the imaging requirements of the projection lens.
[0079] A projection display device includes the projection lens described above, and also includes a spatial light modulator and a projection light source. The projection light source is used to generate illumination light, the illumination light is modulated into image light by the spatial light modulator, the image light is projected to the projection lens, and a projection picture is formed by the projection lens.
[0080] The spatial light modulator and the projection light source adopt the existing technology in the field, and their structure and working principle are not described in detail here.
[0081] This projection display device adopts the projection lens described above, which can be matched with the smallest chip in DLP technology - 0.16-inch DMD, with small lens chromatic aberration and high projection quality.
[0082] The above shows and describes the basic principle, main features and advantages of the utility model. Those skilled in the art should understand that the utility model is not limited by the above embodiments. The above embodiments and descriptions are only for explaining the principle of the utility model. Without departing from the spirit and scope of the utility model, the utility model may have various changes and improvements, which fall within the scope of the utility model to be protected. The scope of protection claimed by the utility model is defined by the attached claims and their equivalents.
Claims
1. A projection lens, characterized in that: A diaphragm, a first lens, a second lens, a third lens, and a fourth lens are sequentially arranged. The first lens and the fourth lens both have positive optical powers, and the second lens and the third lens both have negative optical powers; the second lens and the third lens form a cemented lens.
2. The projection lens according to claim 1, wherein: The first lens and the fourth lens are aspherical lenses, and the second lens and the third lens are spherical lenses.
3. The projection lens according to claim 1, wherein: The first lens is a meniscus aspherical lens, the second lens and the third lens are meniscus spherical lenses, and the fourth lens is a biconvex aspherical lens.
4. The projection lens according to claim 1, wherein: The first lens, the second lens, the third lens, and the fourth lens are all glass lenses.
5. The projection lens according to claim 1, wherein: A turning prism is arranged on one side of the fourth lens away from the third lens.
6. The projection lens according to claim 5, wherein: The turning prism is a right-angle prism.
7. The projection lens according to claim 1, wherein: The total focal length of the projection lens is 5mm < f < 10mm.
8. The projection lens according to claim 1, wherein: The focal length of the first lens is 5 < f1 < 15; the focal length of the second lens is -10 < f2 < -1; the focal length of the third lens is 2 < f3 < 10; the focal length of the fourth lens is 5 < f4 < 15.
9. The projection lens according to claim 5, wherein: The ratio of the center thickness of the first lens to the optical total length of the projection lens is 0.1 < T1 / total length < 0.3; The ratio of the center thickness of the second lens to the optical total length of the projection lens is 0.04 < T2 / total length < 0.2; The ratio of the center thickness of the third lens to the optical total length of the projection lens is 0.1 < T3 / total length < 0.3; The ratio of the center thickness of the fourth lens to the optical total length of the projection lens is 0.1 < T4 / total length < 0.
3.
10. The projection lens according to claim 5, wherein: The ratio of the air gap between the first lens and the second lens to the optical total length of the projection lens is 0.1 ≤ Air1 / total length < 0.3; the ratio of the air gap between the third lens and the fourth lens to the optical total length of the projection lens is 0.001 ≤ Air3 / total length < 0.
1.
11. The projection lens according to claim 5, wherein: The ratio of the air gap between the diaphragm and the first lens to the optical total length of the projection lens is 0 ≤ Air diaphragm / total length < 0.
1.
12. The projection lens according to claim 5, wherein: The ratio of the air gap between the fourth lens and the turning prism to the optical total length of the projection lens is 0.01 ≤ Air4 / total length < 0.
15.
13. The projection lens according to any one of claims 1 to 10, characterized in that: In the direction opposite to the optical path, the two curvature radii of the first lens are 2<R 11 <10 and 5<R 12 <30; the two curvature radii of the second lens are respectively -10<R 21 <10 and -200<R 22 <50; the two curvature radii of the third lens are respectively -200<R 31 <50 and -15<R 32 <-2; the two curvature radii of the fourth lens are 5<R 41 <36 and -20<R 42 <-4.
14. A projection display device, characterized in that: Including the projection lens according to any one of claims 1 to 13, further comprising a spatial light modulator and a projection light source.