Camera lens, projection apparatus, display apparatus, and vehicle

Abstract

A camera lens (100), a projection apparatus (400), a display apparatus (500), and a vehicle, belonging to the technical field of optics. The camera lens (100) comprises a first lens group (10), a diaphragm (20), and a second lens group (30) which are arranged from an image side to an object side. The first lens group (10) comprises at least four lenses, and, along the direction from the image side to the object side, a first lens (11) closest to the image side in the first lens group (10) has a positive focal power, a second lens (12) has a negative focal power, a third lens (13) has a negative focal power, and a fourth lens (14) has a positive focal power. The second lens group (30) comprises at least four lenses, and, along the direction from the image side to the object side, a first lens (31) closest to the diaphragm (20) in the second lens group (30) has a negative focal power, a second lens (32) has a positive focal power, a third lens (33) has a positive focal power, and a fourth lens (34) has a positive focal power. The camera lens (100) has high definition and high reliability, and projection requirements for high definition and high reliability can be met.

Description

Lens, projection device, display device and vehicle

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on December 1, 2023, with application number 202311649342.1 and application name “Lens, projection device, display device and vehicle”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The embodiments of the present application relate to the field of optical technology, and in particular to a lens, a projection device, a display device, and a vehicle. Background Art

[0003] With the development of smart car technology, augmented display head-up display (AR-HUD) has gradually become the mainstream configuration of smart car cockpits. Through the augmented display head-up display, the image to be displayed can be integrated with the real-time road surface, so that the driver can see the speed, navigation, signal lights and other information of the car while looking at the road, so that there is no need to look down at the instrument panel or central control display under the steering wheel, which can greatly improve the braking reaction time in an emergency and improve driving safety. In related technologies, the vehicle-mounted head-up display includes a projection optical engine and a projection lens. The projection optical engine modulates the navigation, instrument and other information to be displayed into a light beam and shoots it to the projection lens. The projection lens projects the image beam onto the projection surface, so that the real-time road surface is integrated with the information to be displayed. However, the existing projection lens has the problem of low clarity. Summary of the Invention

[0004] The embodiments of the present application provide a lens, a projection device, a display device, and a vehicle, which can improve the clarity of the lens.

[0005] In a first aspect, the present application provides a lens comprising a first lens group, an aperture, and a second lens group, arranged from the image side to the object side. The first lens group comprises at least four lens elements, and along the direction from the image side to the object side, the first lens element closest to the image side in the first lens group has positive focal power, the second lens element has negative focal power, the third lens element has negative focal power, and the fourth lens element has positive focal power. The second lens group comprises at least four lens elements, and along the direction from the image side to the object side, the first lens element closest to the aperture has negative focal power, the second lens element has positive focal power, the third lens element has positive focal power, and the fourth lens element has positive focal power.

[0006] Because the four lens elements closest to the image side in the first lens group have a positive-negative-negative-positive power structure, and the four lens elements closest to the aperture in the second lens group have a negative-positive-positive-positive power structure, the imaging capability of the lens is improved, thereby increasing the clarity of the lens to meet the requirements of high-definition lenses. In addition, the reliability of the lens is also improved to meet the requirements of high-reliability lenses.

[0007] In a possible implementation, the lens satisfies the relationship: 13.5 mm ≤ EFL ≤ 14.5 mm, where EFL is the focal length of the lens.

[0008] When the focal length of the lens is between 13.5 mm and 14.5 mm, the imaging capability of the lens can be further improved, and the clarity of the lens can be further improved.

[0009] In a possible implementation, the lens satisfies the relationship: 115 mm ≤ L ≤ 150 mm, where L refers to the distance between the lens closest to the image side and the image in the direction from the image side to the object side.

[0010] When the distance between the lens closest to the image side and the image is between 115mm and 150mm, the clarity can be further improved to meet the requirements of high-definition lenses.

[0011] In a possible implementation, the first lens group satisfies the relationship: -58 mm ≤ EFL1 ≤ -40 mm, where EFL1 refers to the focal length of the first lens group.

[0012] When the focal length of the first lens group is between -58mm and -40mm, the imaging capability of the lens can be further improved, the clarity can be further enhanced, and the compactness of the lens can be improved.

[0013] In a possible implementation, the lens satisfies the relationship: 2≤R1 / EFL≤5, where R1 is the radius of curvature of the image side of the lens element closest to the image side, and EFL is the focal length of the lens.

[0014] When the ratio of the curvature radius of the image side of the lens element closest to the image side to the focal length is between 2 and 5, the image side of the lens element closest to the image side can be prevented from being too flat, which is beneficial for aberration correction. It can also prevent the image side of the lens element closest to the image side from being too protruding, which is beneficial for packaging, transportation, or assembly.

[0015] In a possible implementation, the lens satisfies the relationship: 26 mm ≤ R1 ≤ 70 mm, where R1 is the radius of curvature of the image side of the lens element closest to the image side.

[0016] When the radius of curvature of the image side of the lens element closest to the image side is between 26mm and 70mm, this can prevent the image side of the lens element closest to the image side from being too flat, which is beneficial for aberration correction. It can also prevent the image side of the lens element closest to the image side from being too protruding, which is beneficial for packaging, transportation, or assembly.

[0017] In a possible implementation, the second lens group satisfies the relationship: 19 mm ≤ EFL2 ≤ 25 mm, where EFL2 refers to the focal length of the second lens group.

[0018] When the focal length of the second lens group is between 19mm and 25mm, the imaging capability of the lens can be further improved, which can further enhance the clarity. In addition, the compactness of the lens can be improved. Furthermore, the matching degree between the chief ray angle of the back-end chip (such as the projection chip) and the chief ray angle of the lens can be improved to improve optical efficiency.

[0019] In a possible implementation, the lens satisfies the relationship: -10≤R2 / EFL≤-3, where R2 is the radius of curvature of the object side of the lens element closest to the object side, and EFL is the focal length of the lens.

[0020] When the ratio of the radius of curvature of the object side of the lens closest to the object side to the focal length is between -10 and -3, this aspect of the lens can be prevented from being too flat, facilitating aberration correction. It can also prevent the object side of the lens closest to the object side from being too protruding, facilitating packaging, transportation, or assembly.

[0021] In a possible implementation, the lens satisfies the relationship: -140 mm ≤ R2 ≤ -50 mm, where R2 is the radius of curvature of the object side of the lens element closest to the object side.

[0022] When the radius of curvature of the object side of the lens closest to the object side is between -140mm and -50mm, this aspect of the lens can be prevented from being too flat, facilitating aberration correction. It can also prevent the object side of the lens closest to the object side from being too protruding, facilitating packaging, transportation, or assembly.

[0023] In a possible implementation, the lens satisfies the relationship: 28 mm ≤ BFL ≤ 33 mm, where BFL is the back focal length of the lens.

[0024] When the back focal length of a lens is between 28mm and 33mm, it can prevent the lens's optical path from being too long or too short, thereby expanding the lens's application range. However, an optical path that is too long is not conducive to design, while an optical path that is too short is not conducive to setting up the back-end optical path.

[0025] In one possible embodiment, the first lens group includes a first lens with positive refractive power, a second lens with negative refractive power, a third lens with negative refractive power, and a fourth lens with positive refractive power, arranged from the image side to the object side, with the first lens closest to the image side and the fourth lens closest to the aperture stop. The second lens group includes a fifth lens with negative refractive power, a sixth lens with positive refractive power, a seventh lens with positive refractive power, and an eighth lens with positive refractive power, arranged from the image side to the object side, with the fifth lens closest to the aperture stop and the eighth lens closest to the object side.

[0026] When the first lens group is composed of a first lens element with positive power, a second lens element with negative power, a third lens element with negative power, and a fourth lens element with positive power, and the second lens group is composed of a fifth lens element with negative power, a sixth lens element with positive power, a seventh lens element with positive power, and an eighth lens element with positive power, the imaging capability of the lens can be improved to meet the requirements of high clarity and high reliability. In addition, the number of lens elements can be reduced, thereby reducing the cost of the lens.

[0027] A second aspect of the present application provides a projection device, comprising a display unit and a lens as described in any one of the first aspects, wherein the second lens group of the lens is close to the display unit, wherein the display unit is configured to emit image light toward the lens.

[0028] A third aspect of the present application provides a display device comprising an imaging module and the projection device according to the second aspect, wherein the imaging module generates a target image based on image light emitted by the projection device.

[0029] A fourth aspect of the present application provides a vehicle comprising a display device as described in the third aspect.

[0030] In one possible embodiment, the display device is installed in a dashboard of a vehicle.

[0031] In a possible implementation, the vehicle further includes a windshield, and the image light emitted by the display device is incident on the windshield, and the windshield reflects the image light to human eyes. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG1A is a schematic structural diagram of a usage scenario of a display device provided in an embodiment of the present application;

[0033] FIG1B is a schematic structural diagram of a display device provided in an embodiment of the present application installed on a vehicle;

[0034] FIG2 is a schematic structural diagram of a lens provided in an embodiment of the present application;

[0035] FIG3 is a schematic structural diagram of a first projection device provided in Example 1 of the present application;

[0036] FIG4 is a diagram of spherical chromatic aberration of the lens in FIG3 ;

[0037] FIG5 is a diagram of astigmatism field curvature of the lens in FIG3 ;

[0038] FIG6 is a distortion diagram of the lens in FIG4 ;

[0039] FIG7 is a schematic structural diagram of a second projection device provided in Example 2 of the present application;

[0040] FIG8 is a diagram of spherical chromatic aberration of the lens in FIG7 ;

[0041] FIG9 is a diagram of astigmatism field curvature of the lens in FIG7 ;

[0042] FIG10 is a distortion diagram of the lens in FIG7 ;

[0043] FIG11 is a schematic structural diagram of a third projection device provided in Example 3 of the present application;

[0044] FIG12 is a diagram of spherical chromatic aberration of the lens in FIG11 ;

[0045] FIG13 is a diagram of astigmatism field curvature of the lens in FIG11 ;

[0046] FIG14 is a distortion diagram of the lens in FIG11 ;

[0047] FIG15 is a schematic structural diagram of a fourth projection device provided in Example 4 of the present application;

[0048] FIG16 is a diagram of spherical chromatic aberration of the lens in FIG15 ;

[0049] FIG17 is a diagram of astigmatism field curvature of the lens in FIG15 ;

[0050] FIG18 is a distortion diagram of the lens in FIG15 ;

[0051] FIG19 is a schematic structural diagram of a fifth projection device provided in Example 5 of the present application;

[0052] FIG20 is a diagram of spherical chromatic aberration of the lens in FIG19 ;

[0053] FIG21 is a diagram of astigmatism field curvature of the lens in FIG19 ;

[0054] FIG22 is a distortion diagram of the lens in FIG19 .

[0055] Explanation of the accompanying reference numerals: 100, lens; 10, first lens group; 11, first lens element; 12, second lens element; 13, third lens element; 14, fourth lens element; 20, aperture; 30, second lens group; 31, fifth lens element; 32, sixth lens element; 33, seventh lens element; 34, eighth lens element; 200, modulation unit 300, cover glass; 400, projection device; 500, display device; 600, imaging module; 700, display unit; 710, light source. DETAILED DESCRIPTION

[0056] The terms used in the implementation section of this application are only used to explain the specific embodiments of this application and are not intended to limit this application.

[0057] To facilitate understanding, the relevant technical terms involved in the embodiments of this application are first explained and illustrated.

[0058] Focal length, also known as focal length, is a measure of the convergence or divergence of light in an optical system. It refers to the vertical distance from the optical center of a lens or lens group to the focal plane when an infinitely distant scene forms a clear image on the focal plane through a lens or lens group.

[0059] The image side, with the lens as the boundary, the side where the image is located is the image side, and the side of the lens facing the image side is the image side of the lens.

[0060] The object side is the side where the modulation unit is located, and the side of the lens facing the object side is the object side surface.

[0061] The back focal length (BFL) is defined as the distance from the lens element closest to the imaging surface to the modulation unit.

[0062] Optical power represents the ability of a lens to refract an incident parallel light beam.

[0063] Positive optical power means that the lens has a positive focal length and has the effect of converging light.

[0064] Negative optical power means that the lens has a negative focal length and has the effect of diverging light.

[0065] The aperture is a device used to control the amount of light that passes through the lens and enters the interior of an electronic device. It is usually located inside the lens and is expressed in F# (F-number).

[0066] The aperture number F# is a relative value obtained by dividing the focal length of the lens by the diameter of the lens (the inverse of the relative aperture). The smaller the aperture number F#, the more light enters in the same unit time.

[0067] Cover glass (CG) is used to protect the modulation unit.

[0068] The modulation unit is used to modulate the light beam emitted by the light source to generate image light directed to the lens.

[0069] The projection chip is used to modulate the light beam emitted by the light source to generate image light that is directed to the lens.

[0070] Digital micromirror devices (DMD) are used to reflect light to form images.

[0071] Liquid crystal on silicon (LCOS) is used to reflect light to form images.

[0072] Micro-electro-mechanical systems (MEMS) can reflect light to form images.

[0073] Axial chromatic aberration, also known as longitudinal chromatic aberration or positional chromatic aberration, occurs when a beam of light parallel to the optical axis converges at different positions before and after passing through a lens. This is called positional chromatic aberration or axial chromatic aberration. This is because the lens positions images of different wavelengths of light differently, resulting in images of different colors not completely overlapping on the imaging plane. This causes the complex colors of light to scatter and form dispersion.

[0074] Distortion, also known as distortion, refers to the degree to which the image formed by an optical system is distorted relative to the object itself. Distortion is caused by aperture aberration. The height at which the chief rays of light from different fields of view intersect the Gaussian image plane after passing through the optical system is not equal to the ideal image height. The difference between the two is the distortion. Therefore, distortion only changes the image position of off-axis object points on the ideal plane, distorting the image shape but not affecting image clarity.

[0075] The augmented reality (AR) head-up display (AR-HUD) proposed in recent years can integrate the AR effect of the HUD projection display with the real road information, enhance the driver's acquisition of road information, and realize AR navigation, AR warning and other functions. In related technologies, the enhanced display head-up display includes a projection optical engine and a projection lens. The projection optical engine is used to modulate the navigation, instrument and other information to be displayed into an imaging beam and direct it to the projection lens. The projection lens projects the imaging beam onto the projection surface to form an image, so that the real-time road surface is integrated with the information to be displayed. However, existing projection lenses have problems such as low clarity and low reliability, resulting in poor imaging quality and unable to meet the requirements of high-definition and high-reliability projection.

[0076] In view of this, the embodiments of the present application provide a lens 100, a projection device 400, a display device 500, and a vehicle. The lens 100 has a strong imaging capability, which can improve image clarity to meet the requirements of high-definition projection. In addition, the lens 100 has high reliability, which can meet the requirements of high-reliability projection.

[0077] The means of transportation provided in the embodiments of the present application may include but are not limited to cars, trucks, motorcycles, buses, ships, airplanes, helicopters, lawn mowers, recreational vehicles, amusement park vehicles, construction equipment, trams, golf carts, trains or carts, etc. For example, in the embodiments of the present application, a car is used as an example of the above-mentioned means of transportation, and thus the means of transportation may include components such as a windshield and an instrument panel.

[0078] The display device 500 provided in the embodiment of the present application can be a display, a television or a head-up display, etc. For example, in the embodiment of the present application, a head-up display is used as an example to illustrate the above-mentioned display device 500, as shown in Figure 1A, which is a structural schematic diagram of the use scenario of the display device provided in the embodiment of the present application. Among them, the head-up display (HUD for short) can project navigation information, instrument information, etc. into the driver's front field of view to prevent the driver from lowering his head to view this information, thereby affecting driving safety. After the image projected by the HUD is reflected by the windshield (windshield), a virtual image is formed on the outside of the vehicle. These virtual images can be superimposed on the real environment outside the vehicle, so that the driver can obtain an augmented reality (AR) visual effect, thereby realizing AR navigation, adaptive cruise control, lane departure warning and other functions. Among them, the types of HUD include but are not limited to windshield (W)-HUD, augmented reality head-up display (AR-HUD), etc.

[0079] FIG1B is a schematic structural diagram of a display device provided in an embodiment of the present application installed on a vehicle.

[0080] 1B , the display device 500 can be installed in a vehicle dashboard to achieve a concealed installation. Furthermore, the image light emitted by the display device 500 can be incident on a windshield, which can reflect the image light toward the human eye, allowing the human eye to see a virtual image located outside the windshield.

[0081] 1B , the display device 500 may include a projection device 400 and an imaging module 600 . The imaging module 600 may generate a target image based on the image light emitted by the projection device 400 .

[0082] The imaging module 600 may reflect the image light emitted by the projection device 400 to the windshield, and the windshield may reflect the image light to the human eye to form a target image.

[0083] The specific structure of imaging module 600 is not limited here. For example, as shown in Figure 2, imaging module 600 may include a curved mirror that reflects the image light emitted by projection device 400 toward a windshield, which in turn reflects the image light toward the user's eyes. Furthermore, because the concave surface of the curved mirror reflects the imaging light, the image generated by projection device 400 can be magnified by the curved mirror, allowing the user to see a magnified virtual image.

[0084] 1B , the projection device 400 may include a display unit 700 and a lens 100 . The display unit 700 is configured to emit image light toward the lens 100 , and the lens transmits the image light to the imaging module 600 .

[0085] The display unit 700 may include a light source 710 and a modulation unit 200. The light source 710 is configured to generate a light beam carrying image data of an input image. The modulation unit 200 is configured to modulate the light beam generated by the light source 710 according to the image data and generate image light directed toward the lens 100.

[0086] The specific structure of the modulation unit 200 is not limited here. For example, the modulation unit 200 may be a projection chip. The projection chip may be a reflective spatial light modulator that has the function of changing the polarization direction of incident linearly polarized light, such as an LCoS. Alternatively, the projection chip may be a reflective spatial light modulator that does not have the function of changing the polarization direction of incident linearly polarized light, such as a MEMS or DMD. Alternatively, the projection chip may be a transmissive spatial light modulator, such as an LCD.

[0087] In some possible implementations, the projection device 400 may further include a cover glass 300. The cover glass 300 is disposed between the lens 100 and the modulation unit 200 in the direction from the image side to the object side. The cover glass 300 may protect the modulation unit 200. The number of cover glasses 300 may be one or more, and is not limited herein. When there are multiple cover glasses 300, all of the cover glasses 300 are disposed between the modulation unit 200 and the lens 100.

[0088] The lens 100 provided in the embodiment of the present application is described in detail below with reference to the accompanying drawings.

[0089] Figure 2 is a schematic diagram of the structure of a lens provided in an embodiment of the present application. As shown in Figure 2 , the lens 100 in this embodiment of the present application includes a first lens group 10, an aperture 20, and a second lens group 30, arranged from the image side to the object side. The first lens group 10 is closer to the image side, and the second lens group 30 is closer to the object side. The first lens group 10 includes at least four lens elements. For example, as shown in Figure 2 , the first lens group 10 may include four lens elements. Of course, the number of lens elements in the first lens group 10 may also be more than four. From the image side to the object side, the first lens element closest to the image side in the first lens group 10 has positive power, the second lens element has negative power, the third lens element has negative power, and the fourth lens element has positive power. The second lens group 30 includes at least four lens elements. For example, as shown in Figure 2 , the second lens group 30 may include four lens elements. Of course, the number of lens elements in the second lens group 30 may also be more or less than four. Along the direction from the image side to the object side, the first lens closest to the aperture 20 in the second lens group 30 has negative refractive power, the second lens has positive refractive power, the third lens has positive refractive power, and the fourth lens has positive refractive power.

[0090] As can be seen from FIG. 2 , because the four lens elements closest to the image side in first lens group 10 have a positive-negative-negative-positive power structure, and because the four lens elements closest to aperture 20 in second lens group 30 have a negative-positive-positive-positive power structure, the imaging capability of lens 100 is improved, thereby enhancing the clarity of lens 100 to meet the requirements of a high-definition lens 100. Furthermore, the reliability of lens 100 is also improved to meet the requirements of a high-reliability lens 100.

[0091] There is no limitation on the number of lenses in the first lens group 10 and the second lens group 30. For example, as shown in FIG2 , the first lens group 10 and the second lens group 30 are each composed of four lenses. The first lens group 10 may include, arranged from the image side to the object side, a first lens group 11 with positive refractive power, a second lens group 12 with negative refractive power, a third lens group 13 with negative refractive power, and a fourth lens group 14 with positive refractive power. The first lens group 11 is closest to the image side, and the fourth lens group 14 is closest to the aperture 20. The second lens group 30 may include, arranged from the image side to the object side, a fifth lens group 31 with negative refractive power, a sixth lens group 32 with positive refractive power, a seventh lens group 33 with positive refractive power, and an eighth lens group 34 with positive refractive power. The fifth lens group 31 is closest to the aperture 20, and the eighth lens group 34 is closest to the object side.

[0092] When the first lens group 10 is composed of a first lens element 11 with positive power, a second lens element 12 with negative power, a third lens element 13 with negative power, and a fourth lens element 14 with positive power, and the second lens group 30 is composed of a fifth lens element 31 with negative power, a sixth lens element 32 with positive power, a seventh lens element 33 with positive power, and an eighth lens element 34 with positive power, the lens 100 is composed of eight lens elements. These eight lens elements and the aperture 20 form a four-in-front-four-in-rear structure, which can improve the imaging capability of the lens 100 and meet the requirements of high definition and high reliability for the lens 100. In addition, the number of lens elements can be reduced, thereby reducing the cost of the lens 100.

[0093] It should be noted that when the first lens group 10 includes at least five lenses, the lenses of the first lens group 10 except the four lenses closest to the image side are arranged between the fourth lens closest to the image side and the aperture 20, in other words, between the fourth lens 14 and the aperture 20. Similarly, when the second lens group 30 includes at least five lenses, the lenses of the second lens group 30 except the four lenses closest to the aperture 20 are arranged between the fourth lens closest to the aperture 20 and the object side (or the modulation unit 200), in other words, between the eighth lens 34 and the object side (or the modulation unit 200).

[0094] In some possible implementations, the lens 100 may further satisfy the relationship: 13.5 mm ≤ EFL ≤ 14.5 mm, where EFL is the focal length of the lens 100 .

[0095] Accordingly, when the focal length of the lens 100 is between 13.5 mm and 14.5 mm, the imaging capability of the lens 100 can be further improved, and the clarity of the lens 100 can be further improved.

[0096] There is no limitation on the specific value of the focal length of the lens 100. The focal length of the lens 100 may be 13.5 mm, 13.6 mm, 13.99 mm, 14.0 mm, 14.1 mm, 14.2 mm, 14.3 mm, 14.4 mm, or 14.5 mm.

[0097] In some possible implementations, the lens 100 may also satisfy the relationship: 115 mm ≤ L ≤ 150 mm, where L refers to the distance between the lens closest to the image side in the lens 100 and the image along the direction from the image side to the object side (as shown by L in FIG. 2 ).

[0098] Accordingly, when the distance between the lens element closest to the image side in the lens 100 and the image is between 115 mm and 150 mm, the clarity can be further improved to meet the high-definition requirements of the lens 100 .

[0099] There is no limitation on the specific value of L. L can be 115 mm, 120 mm, 121 mm, 125 mm, 128 mm, 130 mm, 131.5 mm, 135 mm, 139 mm, 140 mm, 143 mm, 145.5 mm, 148 mm, or 150 mm.

[0100] In some possible implementations, the first lens group 10 may further satisfy the relationship: −58 mm ≤ EFL1 ≤ −40 mm, where EFL1 refers to the focal length of the first lens group 10 .

[0101] Accordingly, when the focal length of the first lens group 10 is between -58 mm and -40 mm, the imaging capability of the lens 100 can be further improved, the clarity can be further enhanced, and the compactness of the lens 100 can be improved.

[0102] There is no limitation on the specific focal length of the first lens group 10. The focal length of the first lens group 10 can be -58mm, -57.985mm, -57.5mm, -55mm, -53.6998mm, -50mm, -49mm, -48mm, -47.5mm, -47mm, -46mm, -45mm, -44mm, -43.68mm, -42mm, -41.5mm, -41.35mm, or -40mm, etc.

[0103] In some possible implementations, the lens 100 may further satisfy the relationship: 2≤R1 / EFL≤5, where R1 is the curvature radius of the image side surface of the lens element closest to the image side in the lens 100 , and EFL refers to the focal length of the lens 100 .

[0104] Accordingly, when the ratio of the radius of curvature of the image side surface of the lens element closest to the image side in lens 100 to the focal length of lens 100 is between 2 and 5, the image side surface of the lens element closest to the image side in lens 100 can be prevented from being too flat, which facilitates aberration correction. Furthermore, the image side surface of the lens element closest to the image side in lens 100 can be prevented from being too protruding, which facilitates packaging, transportation, or assembly.

[0105] There is no limitation on the specific ratio of R1 / EFL, and the ratio of R1 / EFL can be 2, 2.5, 2.8, 3, 3.1, 3.5, 3.987, 4, 4.1, 4.5, 4.9 or 5.

[0106] In some possible implementations, the lens 100 may further satisfy the relationship: 26 mm ≤ R1 ≤ 70 mm, where R1 is the curvature radius of the image side surface of the lens element closest to the image side in the lens 100 .

[0107] Accordingly, when the radius of curvature of the image side surface of the lens element closest to the image side in lens 100 is between 26 mm and 70 mm, this can prevent the image side surface of the lens element closest to the image side in lens 100 from being too flat, facilitating aberration correction. Furthermore, this can prevent the image side surface of the lens element closest to the image side in lens 100 from being too protruding, facilitating packaging, transportation, or assembly.

[0108] There is no limitation on the specific value of R1, and the value of R1 can be 26mm, 30mm, 35mm, 40mm, 45mm, 50mm, 55mm, 60mm, 61.698mm, 65mm, 66mm, 69mm, or 70mm.

[0109] In some possible implementations, the second lens group 30 may further satisfy the relationship: 19 mm ≤ EFL2 ≤ 25 mm, where EFL2 refers to the focal length of the second lens group 30 .

[0110] Accordingly, when the focal length of the second lens group 30 is between 19mm and 25mm, the imaging capability of the lens 100 can be further enhanced, further improving clarity. Furthermore, the compactness of the lens 100 can be improved. Furthermore, the matching degree between the principal ray angle of the back-end chip and the principal ray angle of the lens 100 can be improved to improve optical efficiency. The back-end chip refers to the modulation unit 200 closest to the second lens group 30.

[0111] There is no limitation on the specific focal length of the first lens assembly 10. The focal length of the second lens assembly 30 can be 19 mm, 19.5 mm, 20 mm, 21.5 mm, 22 mm, 22.5 mm, 23 mm, 23.509 mm, 24 mm, 24.5 mm, 25 mm, 25.5 mm, or 26 mm, etc.

[0112] In some possible implementations, the lens 100 may further satisfy the relationship: -10≤R2 / EFL≤-3, where R2 is the curvature radius of the object side surface of the lens element closest to the object side in the lens 100 , and EFL is the focal length of the lens 100 .

[0113] Accordingly, when the ratio of the radius of curvature of the object side of the lens element closest to the object side of lens 100 to the focal length of lens 100 is between -10 and -3, the object side of the lens element closest to the object side of lens 100 can be prevented from being too flat, which facilitates aberration correction. Furthermore, the object side of the lens element closest to the object side of lens 100 can be prevented from being too protruding, which facilitates packaging, transportation, or assembly.

[0114] The specific ratio of R2 / EFL is not limited herein, and can be -10, -9.5, -9, -8, -8.5, -8, -7.5, -7, -6.5, -6, -5.5, -5, -4.5, -4, -3.5, or -3, etc.

[0115] In some possible implementations, the lens 100 may further satisfy the relationship: -140 mm ≤ R2 ≤ -50 mm, where R2 is the curvature radius of the object side surface of the lens element closest to the object side in the lens 100 .

[0116] Accordingly, when the radius of curvature of the object side of the lens element closest to the object side in lens 100 is between -140 mm and -50 mm, the object side of the lens element closest to the object side in lens 100 can be prevented from being too flat, which facilitates aberration correction. Furthermore, the object side of the lens element closest to the object side in lens 100 can be prevented from being too protruding, which facilitates packaging, transportation, or assembly.

[0117] There is no limitation on the specific value of R2, and the value of R2 may be -140mm, -135mm, -130mm, -125mm, -120mm, -115mm, -110mm, -105mm, -100mm, -95mm, -90mm, -85mm, -80mm, -75mm, -70mm, -65mm, -60mm, -55mm, or -50mm.

[0118] In some possible implementations, the lens 100 may further satisfy the relationship: 28 mm ≤ BFL ≤ 33 mm, where BFL is the back focal length of the lens 100 .

[0119] Accordingly, when the back focal length of the lens 100 is between 28 mm and 33 mm, the optical path of the lens 100 can be prevented from being too long or too short, thereby increasing the application range of the lens 100. However, an optical path of the lens 100 that is too long is not conducive to design, while an optical path of the lens 100 that is too short is not conducive to the configuration of the rear optical path.

[0120] There is no limitation on the specific value of the back focal length of the lens 100. The focal length of the lens 100 may be 28 mm, 28.6 mm, 29 mm, 29.5 mm, 29.887 mm, 30 mm, 30.5 mm, 31 mm, 31.5 mm, 32 mm, 32.5 mm, or 33 mm.

[0121] The lens 100 and the projection device 400 provided in the embodiments of the present application are described in detail below with reference to specific embodiments.

[0122] FIG3 is a schematic structural diagram of a first projection device provided in Example 1 of the present application.

[0123] As shown in FIG3 , the projection device 400 provided in the first embodiment may include a modulation unit 200, a cover glass 300, and a lens 100. The lens 100 includes a first lens group 10, an aperture 20, and a second lens group 30, arranged from the image side to the object side. In the direction from the image side to the object side, the second lens group 30 is disposed between the aperture 20 and the modulation unit 200, and the cover glass 300 is disposed between the modulation unit 200 and the lens 100. There are three cover glasses 300, which are spaced apart from each other in the direction from the image side to the object side.

[0124] As shown in Figure 3, the first lens assembly 10 includes a first lens 11, a second lens 12, a third lens 13, and a fourth lens 14, arranged in order from the image side to the object side. The first lens 11 is closest to the image side, and the fourth lens 14 is closest to the aperture 20. The first lens 11 has positive optical power, and the focal length f1 of the first lens 11 is 33.05. The second lens 12 has negative optical power, and the focal length f2 of the second lens 12 is -17.32. The third lens 13 has negative optical power, and the focal length f3 of the third lens 13 is -35.85. The fourth lens 14 has positive optical power, and the focal length f4 of the fourth lens 14 is 54.67.

[0125] As shown in Figure 3 , the second lens group 30 may include a fifth lens element 31, a sixth lens element 32, a seventh lens element 33, and an eighth lens element 34, arranged in order from the image side to the object side. The fifth lens element 31 is closest to the aperture 20 and forms a cemented lens with the fifth lens element 31 and the sixth lens element 32. The eighth lens element 34 is closest to the modulation unit 200. The fifth lens element 31 has negative optical power, the sixth lens element 32 has positive optical power, and the cemented lens formed by the fifth lens element 31 and the sixth lens element 32 has positive optical power. The focal length of the cemented lens is f56 = 438.89. The seventh lens element 33 has positive optical power, and the focal length of the seventh lens element 33 is f7 = 101.32. The eighth lens element 34 has positive optical power, and the focal length of the eighth lens element 34 is f8 = 35.1757.

[0126] The lens element closest to the image side in lens 100 is first lens element 11. The radius of curvature of the image side surface of first lens element 11 is 32.67 mm, which is greater than 26 mm and less than 70 mm, meeting the requirements. The ratio of the radius of curvature R1 of the image side surface of first lens element 11 to the focal length EFL of lens 100 is R1 / EFL = 2.099, which is greater than 2 and less than 5, meeting the requirements. The focal length EFL1 of first lens group 10 is -46.327 mm, which is greater than -58 mm and less than -40 mm, meeting the requirements.

[0127] The lens element closest to the object side in lens 100 is eighth lens element 34. The radius of curvature of the object side surface of eighth lens element 34 is -70.84 mm, which is greater than -140 mm and less than -50 mm, meeting the requirements. The ratio of the radius of curvature R2 of the object side surface of eighth lens element 34 to the focal length EFL of lens 100, R2 / EFL = -4.55, is greater than -10 and less than -3, meeting the requirements. The focal length EFL2 of second lens group 30 is 23.11 mm, which is greater than 19 mm and less than 25 mm, meeting the requirements.

[0128] From the image side to the object side, the distance between the object side of the eighth lens element 34 and the modulation unit 200 is 30.81 mm, that is, the back focal length BFL of the lens 100 is 30.81 mm, which is greater than 28 mm and less than 33 mm, meeting the requirements.

[0129] The focal length EFL of the lens 100 is 14.2 mm, which is greater than 13.5 mm and less than 14.5 mm, meeting the requirement.

[0130] Table 1 shows the optical parameters of each optical element in the first projection device 400 provided in the first embodiment of the present application.

[0131] Among them, S1 is the image side surface of the first lens 11, S2 is the object side surface of the first lens 11, S3 is the image side surface of the second lens 12, S4 is the object side surface of the second lens 12, S5 is the image side surface of the third lens 13, S6 is the object side surface of the third lens 13, S7 is the image side surface of the fourth lens 14, S8 is the object side surface of the fourth lens 14, S9 is the aperture 20, S10 is the image side surface of the fifth lens 31, S11 is the bonding surface between the fifth lens 31 and the sixth lens 32, S12 is the object side surface of the sixth lens 32, S13 is the image side surface of the seventh lens 33, S14 is the object side surface of the seventh lens 33, S15 is the eighth lens 34 , S16 is the object side surface of the eighth lens element 34, S17 is the image side surface of the first cover glass 300 close to the lens 100, S18 is the object side surface of the first cover glass 300 close to the lens 100, S19 is the image side surface of the second cover glass 300 close to the lens 100, S20 is the object side surface of the second cover glass 300 close to the lens 100, S21 is the image side surface of the third cover glass 300 close to the lens 100, S22 is the object side surface of the third cover glass 300 close to the lens 100, S23 is the modulation unit 200, OBJ is the projection plane (object plane), and ImgH is the imaging plane.

[0132] Wherein, R is the radius of curvature of the optical element (such as a lens or cover glass 300 ) at the corresponding position on the optical axis, TH is the surface thickness of the optical element along the optical axis, Nd is the refractive index of each optical element irradiated by the d-line, and Vd is the Abbe number of the optical element.

[0133] Table 2 shows the optical parameters of the lens 100 in FIG. 3 .

[0134] Among them, EFL is the focal length of the lens 100, EFL1 is the focal length of the first lens group 10, EFL2 is the focal length of the second lens group 30, Fno is the aperture of the lens 100, BFL is the back focal length of the lens 100, R1 is the radius of curvature of the image side surface of the lens element closest to the image side in the lens 100, R2 is the radius of curvature of the object side surface of the lens element closest to the object side in the lens 100, f1 is the focal length of the first lens element 11, f2 is the focal length of the second lens element 12, f3 is the focal length of the third lens element 13, f4 is the focal length of the fourth lens element 14, f56 is the focal length of the cemented lens formed by the fifth lens element 31 and the sixth lens element 3, f7 is the focal length of the seventh lens element 33, and f8 is the focal length of the eighth lens element 34.

[0135] Figure 4 is a diagram of spherical chromatic aberration for the lens shown in Figure 3. In Figure 4, the ordinate represents the normalized pupil coordinate, and the abscissa represents the axial aberration, both in millimeters. The three curves in Figure 4 correspond to the axial aberration curves for light with a wavelength of 625 nm, light with a wavelength of 550 nm, and light with a wavelength of 455 nm after passing through lens 100 of this embodiment. As can be seen from Figure 4, in this embodiment, the axial aberration is controlled within a very narrow range, resulting in good correction.

[0136] Figure 5 is a plot of astigmatism and field curvature for the lens shown in Figure 3, and Figure 6 is a plot of distortion for the lens shown in Figure 3. In Figure 5, S represents the field curvature for light with a wavelength of 550nm on the meridional image plane, and T represents the field curvature for light with a wavelength of 550nm on the sagittal image plane. In Figure 6, the solid line represents the distortion for light with a central wavelength of 550nm passing through the lens 100 of this embodiment. Combining Figures 5 and 6, it can be seen that the lens 100 provided in this embodiment controls field curvature and distortion within the corresponding ranges, meeting the requirements of use.

[0137] FIG7 is a schematic structural diagram of a second projection device provided in Example 2 of the present application.

[0138] As shown in FIG7 , the projection device 400 provided in the second embodiment may include a modulation unit 200, a cover glass 300, and a lens 100. The lens 100 includes a first lens group 10, an aperture 20, and a second lens group 30, arranged from the image side to the object side. In the direction from the image side to the object side, the second lens group 30 is disposed between the aperture 20 and the modulation unit 200, and the cover glass 300 is disposed between the modulation unit 200 and the lens 100. There are three cover glasses 300, which are spaced apart from each other in the direction from the object side to the image side.

[0139] As shown in Figure 7, the first lens group 10 includes a first lens 11, a second lens 12, a third lens 13, and a fourth lens 14, arranged in order from the image side to the object side. The first lens 11 is closest to the image side, and the fourth lens 14 is closest to the aperture 20. The first lens 11 has positive optical power, and the focal length f1 of the first lens 11 is 60.01. The second lens 12 has negative optical power, and the focal length f2 of the second lens 12 is -17.61. The third lens 13 has negative optical power, and the focal length f3 of the third lens 13 is -50.70. The fourth lens 14 has positive optical power, and the focal length f4 of the fourth lens 14 is 42.26.

[0140] As shown in Figure 7 , the second lens group 30 may include a fifth lens element 31, a sixth lens element 32, a seventh lens element 33, and an eighth lens element 34, arranged in order from the image side to the object side. The fifth lens element 31 is closest to the aperture 20 and forms a cemented lens with the fifth lens element 31 and the sixth lens element 32. The eighth lens element 34 is closest to the modulation unit 200. The fifth lens element 31 has negative optical power, the sixth lens element 32 has positive optical power, and the cemented lens formed by the fifth lens element 31 and the sixth lens element 32 has negative optical power. The focal length of the cemented lens is f56 = -2729.326. The seventh lens element 33 has positive optical power, and the focal length of the seventh lens element 33 is f7 = 80.60. The eighth lens element 34 has positive optical power, and the focal length of the eighth lens element 34 is f8 = 37.05.

[0141] The lens element closest to the image side in lens 100 is first lens element 11. The radius of curvature of the image side surface of first lens element 11 is 28.01 mm, which is greater than 26 mm and less than 70 mm, meeting the requirements. The ratio of the radius of curvature R1 of the image side surface of first lens element 11 to the focal length EFL of lens 100, R1 / EFL = 2.0122, is greater than 2 and less than 5, meeting the requirements. The focal length EFL1 of first lens group 10 is -57.386 mm, which is greater than -58 mm and less than -40 mm, meeting the requirements.

[0142] The lens element closest to the object side in lens 100 is eighth lens element 34. The radius of curvature of the object side surface of eighth lens element 34 is -115.75 mm, which is greater than -140 mm and less than -50 mm, meeting the requirements. The ratio of the radius of curvature R2 of the object side surface of eighth lens element 34 to the focal length EFL of lens 100, R2 / EFL = -8.32, is greater than -10 and less than -3, meeting the requirements. The focal length EFL2 of second lens group 30 is 24.323 mm, which is greater than 19 mm and less than 25 mm, meeting the requirements.

[0143] From the image side to the object side, the distance between the object side of the eighth lens element 34 and the modulation unit 200 is 30.83 mm, that is, the back focal length BFL of the lens 100 is 30.83 mm, which is greater than 28 mm and less than 33 mm, meeting the requirements.

[0144] The focal length EFL of the lens 100 is 13.91 mm, which is greater than 13.5 mm and less than 14.5 mm, meeting the requirements.

[0145] Table 3 shows the optical parameters of each optical element in the second projection device 400 provided in the second embodiment of the present application.

[0146] Among them, S1 is the image side surface of the first lens 11, S2 is the object side surface of the first lens 11, S3 is the image side surface of the second lens 12, S4 is the object side surface of the second lens 12, S5 is the image side surface of the third lens 13, S6 is the object side surface of the third lens 13, S7 is the image side surface of the fourth lens 14, S8 is the object side surface of the fourth lens 14, S9 is the aperture 20, S10 is the image side surface of the fifth lens 31, S11 is the bonding surface between the fifth lens 31 and the sixth lens 32, S12 is the object side surface of the sixth lens 32, S13 is the image side surface of the seventh lens 33, S14 is the object side surface of the seventh lens 33, S15 is the eighth lens 34 , S16 is the object side surface of the eighth lens element 34, S17 is the image side surface of the first cover glass 300 close to the lens 100, S18 is the object side surface of the first cover glass 300 close to the lens 100, S19 is the image side surface of the second cover glass 300 close to the lens 100, S20 is the object side surface of the second cover glass 300 close to the lens 100, S21 is the image side surface of the third cover glass 300 close to the lens 100, S22 is the object side surface of the third cover glass 300 close to the lens 100, S23 is the modulation unit 200, OBJ is the projection plane (object plane), and ImgH is the imaging plane.

[0147] Wherein, R is the radius of curvature of the optical element (such as a lens or cover glass 300 ) at the corresponding position on the optical axis, TH is the surface thickness of the optical element along the optical axis, Nd is the refractive index of each optical element irradiated by the d-line, and Vd is the Abbe number of the optical element.

[0148] Table 4 shows the optical parameters of the lens 100 in FIG. 7 .

[0149] Among them, EFL is the focal length of the lens 100, EFL1 is the focal length of the first lens group 10, EFL2 is the focal length of the second lens group 30, Fno is the aperture of the lens 100, BFL is the back focal length of the lens 100, R1 is the radius of curvature of the image side surface of the lens element closest to the image side in the lens 100, R2 is the radius of curvature of the object side surface of the lens element closest to the object side in the lens 100, f1 is the focal length of the first lens element 11, f2 is the focal length of the second lens element 12, f3 is the focal length of the third lens element 13, f4 is the focal length of the fourth lens element 14, f56 is the focal length of the cemented lens formed by the fifth lens element 31 and the sixth lens element 3, f7 is the focal length of the seventh lens element 33, and f8 is the focal length of the eighth lens element 34.

[0150] Figure 8 is a diagram of spherical chromatic aberration for the lens shown in Figure 7. In Figure 8, the ordinate represents the normalized pupil coordinate, and the abscissa represents the axial aberration, both in millimeters. The three curves in Figure 8 correspond to the axial aberration curves for light with a wavelength of 625 nm, light with a wavelength of 550 nm, and light with a wavelength of 455 nm after passing through the lens 100 of this embodiment. As can be seen from Figure 8, in this embodiment, the axial aberration is controlled within a very narrow range, resulting in good correction.

[0151] Figure 9 shows the astigmatism field curvature of the lens shown in Figure 7, and Figure 10 shows the distortion of the lens shown in Figure 7. In Figure 9, S represents the field curvature of light with a wavelength of 550nm on the meridional image plane, and T represents the field curvature of light with a wavelength of 550nm on the sagittal image plane. In Figure 10, the solid line represents the distortion of light with a central wavelength of 550nm passing through the lens 100 of this embodiment. Combining Figures 9 and 10, it can be seen that the lens 100 provided in this embodiment controls field curvature and distortion within the corresponding ranges, meeting the requirements of use.

[0152] FIG11 is a schematic structural diagram of a third projection device provided in Example 3 of the present application.

[0153] As shown in FIG11 , the projection device 400 provided in the third embodiment may include a modulation unit 200, a cover glass 300, and a lens 100. The lens 100 includes a first lens group 10, an aperture 20, and a second lens group 30, arranged from the image side to the object side. In the direction from the image side to the object side, the second lens group 30 is disposed between the aperture 20 and the modulation unit 200, and the cover glass 300 is disposed between the modulation unit 200 and the lens 100. There are three cover glasses 300, which are spaced apart from each other in the direction from the object side to the image side.

[0154] As shown in Figure 11, the first lens group 10 may include a first lens 11, a second lens 12, a third lens 13, and a fourth lens 14, arranged in order from the image side to the object side. The first lens 11 is closest to the image side, and the fourth lens 14 is closest to the aperture 20. The first lens 11 has positive optical power, and the focal length f1 of the first lens 11 is 33.76. The second lens 12 has negative optical power, and the focal length f2 of the second lens 12 is -16.56. The third lens 13 has negative optical power, and the focal length f3 of the third lens 13 is -39.08. The fourth lens 14 has positive optical power, and the focal length f4 of the fourth lens 14 is 43.78.

[0155] As shown in Figure 11 , the second lens group 30 may include a fifth lens element 31, a sixth lens element 32, a seventh lens element 33, and an eighth lens element 34, arranged in order from the image side to the object side. The fifth lens element 31 is closest to the aperture 20 and forms a cemented lens with the fifth lens element 31 and the sixth lens element 32. The eighth lens element 34 is closest to the modulation unit 200. The fifth lens element 31 has negative optical power, the sixth lens element 32 has positive optical power, and the cemented lens formed by the fifth lens element 31 and the sixth lens element 32 has positive optical power. The focal length of the cemented lens is f56 = 3992.74. The seventh lens element 33 has positive optical power, and the focal length of the seventh lens element 33 is f7 = 91.10. The eighth lens element 34 has positive optical power, and the focal length of the eighth lens element 34 is f8 = 35.08.

[0156] The lens element closest to the image side in lens 100 is first lens element 11. The radius of curvature of the image side surface of first lens element 11 is 32.35 mm, which is greater than 26 mm and less than 70 mm, meeting the requirements. The ratio of the radius of curvature R1 of the image side surface of first lens element 11 to the focal length EFL of lens 100 is R1 / EFL = 2.267, which is greater than 2 and less than 5, meeting the requirements. The focal length EFL1 of first lens group 10 is -55.992 mm, which is greater than -58 mm and less than -40 mm, meeting the requirements.

[0157] The lens element closest to the object side in lens 100 is eighth lens element 34. The radius of curvature of the object side surface of eighth lens element 34 is -70.02 mm, which is greater than -140 mm and less than -50 mm, meeting the requirements. The ratio of the radius of curvature R2 of the object side surface of eighth lens element 34 to the focal length EFL of lens 100, R2 / EFL = -4.908, is greater than -10 and less than -3, meeting the requirements. The focal length EFL2 of second lens group 30 is 22.981 mm, which is greater than 19 mm and less than 25 mm, meeting the requirements.

[0158] From the image side to the object side, the distance between the object side of the eighth lens element 34 and the modulation unit 200 is 30.83 mm, that is, the back focal length BFL of the lens 100 is 30.83 mm, which is greater than 28 mm and less than 33 mm, meeting the requirements.

[0159] The focal length EFL of the lens 100 is 14.266 mm, which is greater than 13.5 mm and less than 14.5 mm, meeting the requirement.

[0160] Table 5 shows the optical parameters of each optical element in the third projection device 400 provided in Example 3 of the present application.

[0161] Among them, S1 is the image side surface of the first lens 11, S2 is the object side surface of the first lens 11, S3 is the image side surface of the second lens 12, S4 is the object side surface of the second lens 12, S5 is the image side surface of the third lens 13, S6 is the object side surface of the third lens 13, S7 is the image side surface of the fourth lens 14, S8 is the object side surface of the fourth lens 14, S9 is the aperture 20, S10 is the image side surface of the fifth lens 31, S11 is the bonding surface between the fifth lens 31 and the sixth lens 32, S12 is the object side surface of the sixth lens 32, S13 is the image side surface of the seventh lens 33, S14 is the object side surface of the seventh lens 33, S15 is the eighth lens 34 , S16 is the object side surface of the eighth lens element 34, S17 is the image side surface of the first cover glass 300 close to the lens 100, S18 is the object side surface of the first cover glass 300 close to the lens 100, S19 is the image side surface of the second cover glass 300 close to the lens 100, S20 is the object side surface of the second cover glass 300 close to the lens 100, S21 is the image side surface of the third cover glass 300 close to the lens 100, S22 is the object side surface of the third cover glass 300 close to the lens 100, S23 is the modulation unit 200, OBJ is the projection plane (object plane), and ImgH is the imaging plane.

[0162] Wherein, R is the radius of curvature of the optical element (such as a lens or cover glass 300 ) at the corresponding position on the optical axis, TH is the surface thickness of the optical element along the optical axis, Nd is the refractive index of each optical element irradiated by the d-line, and Vd is the Abbe number of the optical element.

[0163] Table 6 shows the optical parameters of the lens 100 in FIG11 .

[0164] Among them, EFL is the focal length of the lens 100, EFL1 is the focal length of the first lens group 10, EFL2 is the focal length of the second lens group 30, Fno is the aperture of the lens 100, BFL is the back focal length of the lens 100, R1 is the radius of curvature of the image side surface of the lens element closest to the image side in the lens 100, R2 is the radius of curvature of the object side surface of the lens element closest to the object side in the lens 100, f1 is the focal length of the first lens element 11, f2 is the focal length of the second lens element 12, f3 is the focal length of the third lens element 13, f4 is the focal length of the fourth lens element 14, f56 is the focal length of the cemented lens formed by the fifth lens element 31 and the sixth lens element 3, f7 is the focal length of the seventh lens element 33, and f8 is the focal length of the eighth lens element 34.

[0165] Figure 12 is a diagram of spherical chromatic aberration of the lens shown in Figure 11. In Figure 12, the ordinate represents the normalized pupil coordinate, and the abscissa represents the axial aberration, both in millimeters. The three curves in Figure 12 correspond to the axial aberration curves for light with a wavelength of 625 nm, light with a wavelength of 550 nm, and light with a wavelength of 455 nm after passing through the lens 100 of this embodiment. As can be seen from Figure 12, in this embodiment, the axial aberration is controlled within a very narrow range, resulting in good correction.

[0166] Figure 13 is a plot of astigmatism and field curvature for the lens shown in Figure 11, and Figure 14 is a plot of distortion for the lens shown in Figure 11. In Figure 13, S represents the field curvature of light with a wavelength of 550nm on the meridional image plane, and T represents the field curvature of light with a wavelength of 550nm on the sagittal image plane. In Figure 14, the solid line represents the distortion of light with a central wavelength of 550nm passing through the lens 100 of this embodiment. Combining Figures 13 and 14, it can be seen that the lens 100 provided in this embodiment controls field curvature and distortion within the corresponding ranges, meeting the requirements of use.

[0167] FIG15 is a schematic structural diagram of a fourth projection device provided in Example 4 of the present application.

[0168] As shown in FIG15 , the projection device 400 provided in the fourth embodiment may include a modulation unit 200, a cover glass 300, and a lens 100. The lens 100 includes a first lens group 10, an aperture 20, and a second lens group 30, arranged from the image side to the object side. In the direction from the image side to the object side, the second lens group 30 is disposed between the aperture 20 and the modulation unit 200, and the cover glass 300 is disposed between the modulation unit 200 and the lens 100. There are three cover glasses 300, which are spaced apart from each other in the direction from the object side to the image side.

[0169] As shown in Figure 15 , the first lens group 10 may include a first lens 11, a second lens 12, a third lens 13, and a fourth lens 14, arranged in order from the image side to the object side. The first lens 11 is closest to the image side, and the fourth lens 14 is closest to the aperture 20. The first lens 11 has positive optical power, and a focal length f1 of 33.05. The second lens 12 has negative optical power, and a focal length f2 of -14.19. The third lens 13 has negative optical power, and a focal length f3 of -73.9. The fourth lens 14 has positive optical power, and a focal length f4 of 80.54.

[0170] As shown in Figure 15 , the second lens group 30 may include a fifth lens element 31, a sixth lens element 32, a seventh lens element 33, and an eighth lens element 34, arranged in order from the image side to the object side. The fifth lens element 31 is closest to the aperture 20 and forms a cemented lens with the fifth lens element 31 and the sixth lens element 32. The eighth lens element 34 is closest to the modulation unit 200. The fifth lens element 31 has negative optical power, the sixth lens element 32 has positive optical power, and the cemented lens formed by the fifth lens element 31 and the sixth lens element 32 has positive optical power. The focal length of the cemented lens is f56 = 263.74. The seventh lens element 33 has positive optical power, and the focal length of the seventh lens element 33 is f7 = 101.32. The eighth lens element 34 has positive optical power, and the focal length of the eighth lens element 34 is f8 = 35.18.

[0171] The lens element closest to the image side in lens 100 is first lens element 11. The radius of curvature of the image side surface of first lens element 11 is 32.67 mm, which is greater than 26 mm and less than 70 mm, meeting the requirements. The ratio of the radius of curvature R1 of the image side surface of first lens element 11 to the focal length EFL of lens 100, R1 / EFL = 2.317, is greater than 2 and less than 5, meeting the requirements. The focal length EFL1 of first lens group 10 is -45.742 mm, which is greater than -58 mm and less than -40 mm, meeting the requirements.

[0172] The lens element closest to the object side in lens 100 is eighth lens element 34. The radius of curvature of the object side surface of eighth lens element 34 is -70.84 mm, which is greater than -140 mm and less than -50 mm, meeting the requirements. The ratio of the radius of curvature R2 of the object side surface of eighth lens element 34 to the focal length EFL of lens 100, R2 / EFL = -5.023, is greater than -10 and less than -3, meeting the requirements. The focal length EFL2 of second lens group 30 is 23.880 mm, which is greater than 19 mm and less than 25 mm, meeting the requirements.

[0173] From the image side to the object side, the distance between the object side of the eighth lens element 34 and the modulation unit 200 is 30.81 mm, that is, the back focal length BFL of the lens 100 is 30.81 mm, which is greater than 28 mm and less than 33 mm, meeting the requirements.

[0174] The focal length EFL of the lens 100 is 14.102 mm, which is greater than 13.5 mm and less than 14.5 mm, meeting the requirement.

[0175] Table 7 shows the optical parameters of each optical element in the fourth projection device 400 provided in the fourth embodiment of the present application.

[0176] Among them, S1 is the image side surface of the first lens 11, S2 is the object side surface of the first lens 11, S3 is the image side surface of the second lens 12, S4 is the object side surface of the second lens 12, S5 is the image side surface of the third lens 13, S6 is the object side surface of the third lens 13, S7 is the image side surface of the fourth lens 14, S8 is the object side surface of the fourth lens 14, S9 is the aperture 20, S10 is the image side surface of the fifth lens 31, S11 is the bonding surface between the fifth lens 31 and the sixth lens 32, S12 is the object side surface of the sixth lens 32, S13 is the image side surface of the seventh lens 33, S14 is the object side surface of the seventh lens 33, S15 is the eighth lens 34 , S16 is the object side surface of the eighth lens element 34, S17 is the image side surface of the first cover glass 300 close to the lens 100, S18 is the object side surface of the first cover glass 300 close to the lens 100, S19 is the image side surface of the second cover glass 300 close to the lens 100, S20 is the object side surface of the second cover glass 300 close to the lens 100, S21 is the image side surface of the third cover glass 300 close to the lens 100, S22 is the object side surface of the third cover glass 300 close to the lens 100, S23 is the modulation unit 200, OBJ is the projection plane (object plane), and ImgH is the imaging plane.

[0177] Wherein, R is the radius of curvature of the optical element (such as a lens or cover glass 300 ) at the corresponding position on the optical axis, TH is the surface thickness of the optical element along the optical axis, Nd is the refractive index of each optical element irradiated by the d-line, and Vd is the Abbe number of the optical element.

[0178] Table 8 shows optical parameters of the lens 100 in FIG15 .

[0179] Among them, EFL is the focal length of the lens 100, EFL1 is the focal length of the first lens group 10, EFL2 is the focal length of the second lens group 30, Fno is the aperture of the lens 100, BFL is the back focal length of the lens 100, R1 is the radius of curvature of the image side surface of the lens element closest to the image side in the lens 100, R2 is the radius of curvature of the object side surface of the lens element closest to the object side in the lens 100, f1 is the focal length of the first lens element 11, f2 is the focal length of the second lens element 12, f3 is the focal length of the third lens element 13, f4 is the focal length of the fourth lens element 14, f56 is the focal length of the cemented lens formed by the fifth lens element 31 and the sixth lens element 3, f7 is the focal length of the seventh lens element 33, and f8 is the focal length of the eighth lens element 34.

[0180] Figure 16 is a diagram of spherical chromatic aberration for the lens shown in Figure 15. In Figure 16, the ordinate represents the normalized pupil coordinate, and the abscissa represents the axial aberration, both in millimeters. The three curves in Figure 16 correspond to the axial aberration curves for light with a wavelength of 625 nm, light with a wavelength of 550 nm, and light with a wavelength of 455 nm after passing through the lens 100 of this embodiment. As can be seen from Figure 16, in this embodiment, the axial aberration is controlled within a very narrow range, resulting in good correction.

[0181] Figure 17 is a plot of astigmatism and field curvature for the lens shown in Figure 15, and Figure 18 is a plot of distortion for the lens shown in Figure 15. In Figure 17, S represents the field curvature of light with a wavelength of 550nm on the meridional image plane, and T represents the field curvature of light with a wavelength of 550nm on the sagittal image plane. In Figure 18, the solid line represents the distortion of light with a central wavelength of 550nm passing through the lens 100 of this embodiment. Combining Figures 17 and 18, it can be seen that the lens 100 provided in this embodiment controls field curvature and distortion within the corresponding ranges, meeting the requirements of use.

[0182] FIG19 is a schematic structural diagram of the fifth projection device provided in Example 5 of the present application.

[0183] As shown in FIG19 , the projection device 400 provided in Example 5 may include a modulation unit 200, a cover glass 300, and a lens 100. The lens 100 includes a first lens group 10, an aperture 20, and a second lens group 30, arranged from the image side to the object side. In the direction from the image side to the object side, the second lens group 30 is disposed between the aperture 20 and the modulation unit 200, and the cover glass 300 is disposed between the modulation unit 200 and the lens 100. There are three cover glasses 300.

[0184] As shown in FIG19 , the first lens group 10 may include a first lens 11, a second lens 12, a third lens 13, and a fourth lens 14, arranged in order from the image side to the object side. The first lens 11 is closest to the image side, and the fourth lens 14 is closest to the aperture 20. The first lens 11 has positive optical power, and a focal length f1 of 33.05. The second lens 12 has negative optical power, and a focal length f2 of -15.41. The third lens 13 has negative optical power, and a focal length f3 of -33.46. The fourth lens 14 has positive optical power, and a focal length f4 of 44.42.

[0185] As shown in FIG19 , the second lens group 30 may include a fifth lens element 31, a sixth lens element 32, a seventh lens element 33, and an eighth lens element 34, arranged in order from the image side to the object side. The fifth lens element 31 is closest to the aperture 20 and forms a cemented lens with the fifth lens element 31 and the sixth lens element 32. The eighth lens element 34 is closest to the modulation unit 200. The fifth lens element 31 has negative optical power, the sixth lens element 32 has positive optical power, and the cemented lens formed by the fifth lens element 31 and the sixth lens element 32 has positive optical power. The focal length of the cemented lens is f56 = 354.70. The seventh lens element 33 has positive optical power, and the focal length of the seventh lens element 33 is f7 = 101.32. The eighth lens element 34 has positive optical power, and the focal length of the eighth lens element 34 is f8 = 35.18.

[0186] The lens element closest to the image side in lens 100 is first lens element 11. The radius of curvature of the image side surface of first lens element 11 is 32.67 mm, which is greater than 26 mm and less than 70 mm, meeting the requirements. The ratio of the radius of curvature R1 of the image side surface of first lens element 11 to the focal length EFL of lens 100 is R1 / EFL = 2.317, which is greater than 2 and less than 5, meeting the requirements. The focal length EFL1 of first lens group 10 is -48.652 mm, which is greater than -58 mm and less than -40 mm, meeting the requirements.

[0187] The lens element closest to the object side in lens 100 is eighth lens element 34. The radius of curvature of the object side surface of eighth lens element 34 is -70.84 mm, which is greater than -140 mm and less than -50 mm, meeting the requirements. The ratio of the radius of curvature R2 of the object side surface of eighth lens element 34 to the focal length EFL of lens 100, R2 / EFL = -5.023, is greater than -10 and less than -3, meeting the requirements. The focal length EFL2 of second lens group 30 is 23.122 mm, which is greater than 19 mm and less than 25 mm, meeting the requirements.

[0188] From the image side to the object side, the distance between the object side of the eighth lens element 34 and the modulation unit 200 is 30.81 mm, that is, the back focal length BFL of the lens 100 is 30.81 mm, which is greater than 28 mm and less than 33 mm, meeting the requirements.

[0189] The focal length EFL of the lens 100 is 14.103 mm, which is greater than 13.5 mm and less than 14.5 mm, meeting the requirement.

[0190] Table 9 shows the optical parameters of each optical element in the fifth projection device 400 provided in Example 5 of the present application.

[0191] Among them, S1 is the image side surface of the first lens 11, S2 is the object side surface of the first lens 11, S3 is the image side surface of the second lens 12, S4 is the object side surface of the second lens 12, S5 is the image side surface of the third lens 13, S6 is the object side surface of the third lens 13, S7 is the image side surface of the fourth lens 14, S8 is the object side surface of the fourth lens 14, S9 is the aperture 20, S10 is the image side surface of the fifth lens 31, S11 is the bonding surface between the fifth lens 31 and the sixth lens 32, S12 is the object side surface of the sixth lens 32, S13 is the image side surface of the seventh lens 33, S14 is the object side surface of the seventh lens 33, S15 is the eighth lens 34 , S16 is the object side surface of the eighth lens element 34, S17 is the image side surface of the first cover glass 300 close to the lens 100, S18 is the object side surface of the first cover glass 300 close to the lens 100, S19 is the image side surface of the second cover glass 300 close to the lens 100, S20 is the object side surface of the second cover glass 300 close to the lens 100, S21 is the image side surface of the third cover glass 300 close to the lens 100, S22 is the object side surface of the third cover glass 300 close to the lens 100, S23 is the modulation unit 200, OBJ is the projection plane (object plane), and ImgH is the imaging plane.

[0192] Wherein, R is the radius of curvature of the optical element (such as a lens or cover glass 300 ) at the corresponding position on the optical axis, TH is the surface thickness of the optical element along the optical axis, Nd is the refractive index of each optical element irradiated by the d-line, and Vd is the Abbe number of the optical element.

[0193] Table 10 shows optical parameters of the lens 100 in FIG. 19 .

[0194] Among them, EFL is the focal length of the lens 100, EFL1 is the focal length of the first lens group 10, EFL2 is the focal length of the second lens group 30, Fno is the aperture of the lens 100, BFL is the back focal length of the lens 100, R1 is the radius of curvature of the image side surface of the lens element closest to the image side in the lens 100, R2 is the radius of curvature of the object side surface of the lens element closest to the object side in the lens 100, f1 is the focal length of the first lens element 11, f2 is the focal length of the second lens element 12, f3 is the focal length of the third lens element 13, f4 is the focal length of the fourth lens element 14, f56 is the focal length of the cemented lens formed by the fifth lens element 31 and the sixth lens element 3, f7 is the focal length of the seventh lens element 33, and f8 is the focal length of the eighth lens element 34.

[0195] Figure 20 is a diagram of spherical chromatic aberration for the lens shown in Figure 19. In Figure 20, the ordinate represents the normalized pupil coordinate, and the abscissa represents the axial aberration, both in millimeters. The three curves in Figure 20 correspond to the axial aberration curves for light with a wavelength of 625 nm, light with a wavelength of 550 nm, and light with a wavelength of 455 nm after passing through the lens 100 of this embodiment. As can be seen from Figure 20, in this embodiment, the axial aberration is controlled within a very narrow range, resulting in good correction.

[0196] Figure 21 is a plot of astigmatism and field curvature for the lens shown in Figure 19, and Figure 22 is a plot of distortion for the lens shown in Figure 19. In Figure 21, S represents the field curvature of light with a wavelength of 550nm on the meridional image plane, and T represents the field curvature of light with a wavelength of 550nm on the sagittal image plane. In Figure 22, the solid line represents the distortion of light with a central wavelength of 550nm passing through the lens 100 of this embodiment. Combining Figures 21 and 22, it can be seen that the lens 100 provided in this embodiment controls field curvature and distortion within the corresponding ranges, meeting the requirements of use.

[0197] In the description of the embodiments of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to a fixed connection, an indirect connection via an intermediate medium, internal communication between two components, or an interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the embodiments of this application based on specific circumstances.

[0198] In the embodiments of the present application, any device or element referred to or implied must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be understood as limiting the embodiments of the present application. In the description of the embodiments of the present application, the meaning of "plurality" is two or more, unless otherwise specifically specified.

[0199] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the embodiments of the present application and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the embodiments of the present application described herein can, for example, be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0200] The term "plurality" in this document refers to two or more. The term "and / or" in this document simply describes a relationship between related objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A alone, A and B together, or B alone. Furthermore, the character " / " in this document generally indicates an "or" relationship between the related objects; in a formula, the character " / " indicates a "division" relationship between the related objects.

[0201] It will be understood that the various numerical numbers involved in the embodiments of the present application are merely distinctions for the convenience of description and are not intended to limit the scope of the embodiments of the present application.

[0202] It can be understood that in the embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

Claims

1. A lens, characterized in that: It includes a first lens group, an aperture, and a second lens group arranged from the image side to the object side; The first lens group includes at least four lenses, and along the direction from the image side to the object side, the first lens closest to the image side in the first lens group has positive power, the second lens has negative power, the third lens has negative power, and the fourth lens has positive power; The second lens group includes at least four lenses. Along the direction from the image side to the object side, the first lens closest to the aperture stop in the second lens group has negative optical power, the second lens has positive optical power, the third lens has positive optical power and the fourth lens has positive optical power.

2. The lens according to claim 1, characterized in that: The lens satisfies the relationship: 13.5 mm ≤ EFL ≤ 14.5 mm, and the EFL is the focal length of the lens.

3. The lens according to claim 1 or 2, characterized in that: The lens satisfies the relationship: 115mm≤L≤150mm, and along the direction from the image side to the object side, L refers to the distance between the lens closest to the image side in the lens and the image.

4. The lens according to any one of claims 1 to 3, characterized in that: The first lens group satisfies the relationship: -58mm≤EFL1≤-40mm, and EFL1 refers to the focal length of the first lens group.

5. The lens according to any one of claims 1 to 4, characterized in that: The lens satisfies the relationship: 2≤R1 / EFL≤5, wherein R1 is the radius of curvature of the image side surface of the lens closest to the image side in the lens, and EFL is the focal length of the lens.

6. The lens according to any one of claims 1 to 5, characterized in that: The lens satisfies the relationship: 26mm≤R1≤70mm, where R1 is the radius of curvature of the image side of the lens closest to the image side in the lens.

7. The lens according to any one of claims 1 to 6, characterized in that: The second lens group satisfies the relationship: 19mm≤EFL2≤25mm, and EFL2 refers to the focal length of the second lens group.

8. The lens according to any one of claims 1 to 7, characterized in that: The lens satisfies the relationship: -10≤R2 / EFL≤-3, wherein R2 is the radius of curvature of the object side surface of the lens closest to the object side in the lens, and EFL is the focal length of the lens.

9. The lens according to any one of claims 1 to 8, characterized in that: The lens satisfies the relationship: -140mm≤R2≤-50mm, where R2 is the radius of curvature of the object side of the lens closest to the object side in the lens.

10. The lens according to any one of claims 1 to 9, characterized in that: The lens satisfies the relationship: 28mm≤BFL≤33mm, and the BFL is the back focal length of the lens.

11. The lens according to any one of claims 1 to 10, characterized in that: The first lens group includes a first lens with positive power, a second lens with negative power, a third lens with negative power, and a fourth lens with positive power arranged from the image side to the object side, the first lens is closest to the image side, and the fourth lens is closest to the aperture stop; The second lens group includes a fifth lens with negative optical power, a sixth lens with positive optical power, a seventh lens with positive optical power and an eighth lens with positive optical power arranged from the image side to the object side, the fifth lens is closest to the aperture stop, and the eighth lens is closest to the object side.

12. A projection device, characterized in that: The device comprises a display unit and the lens according to any one of claims 1 to 11, wherein the second lens group of the lens is close to the display unit; The display unit is used to emit image light toward the lens.

13. A display device, characterized in that: comprising an imaging module and a projection device as claimed in claim 12; The imaging module generates a target image based on the image light emitted by the projection device.

14. A means of transport, characterized in that: Comprising the display device as claimed in claim 13.

15. The vehicle according to claim 14, characterized in that: The display device is installed in a dashboard of the vehicle. 16 . The vehicle according to claim 14 or 15 , further comprising a windshield, the image light emitted by the display device is incident on the windshield, and the windshield reflects the image light to human eyes.

Images