Projection lens and projection device

Abstract

The application discloses a projection lens and a projection device. The projection lens comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens unit. The first lens has a negative focal power, the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a concave surface. The second lens has a positive focal power, the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a convex surface. The third lens has a negative focal power, the object side surface of the third lens is a convex surface, and the image side surface of the third lens is a concave surface. The fourth lens has a negative focal power, the object side surface of the fourth lens is a concave surface, and the image side surface of the fourth lens is a concave surface. The fifth lens has a positive focal power, the object side surface of the fifth lens is a convex surface, and the image side surface of the fifth lens is a convex surface. The sixth lens unit has a positive focal power, and the object side surface of the sixth lens unit is a convex surface. The projection lens disclosed by the application can realize the function of image-side telecentricity, and has the characteristics of miniaturization, small distortion and high image quality.

Description

Technical Field

[0001] This application relates to the field of optical imaging technology, and more specifically, to a projection lens and a projection device. Background Technology

[0002] With the increasing popularity and development of vehicles, cars equipped with dynamic welcome lights are becoming more and more popular among consumers. Specifically, dynamic welcome lights can project preset patterns (such as brand logos, welcome messages, dynamic effects, etc.) onto the ground or other locations through projection lenses and micro-projector modules, creating a unique welcoming ceremony for car owners and passengers, thereby enhancing the user's riding experience.

[0003] Therefore, designing a compact projection lens with high image quality became the main goal of the researchers. Utility Model Content

[0004] This application provides a projection lens and a projection device.

[0005] According to a first aspect of this application, an embodiment of this application provides a projection lens, which includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens unit arranged sequentially along the optical axis from the object side to the image side. The first lens has negative optical power, its object side is convex, and its image side is concave; the second lens has positive optical power, its object side is convex, and its image side is convex; the third lens has negative optical power, its object side is convex, and its image side is concave; the fourth lens has negative optical power, its object side is concave, and its image side is concave; the fifth lens has positive optical power, its object side is convex, and its image side is convex; the sixth lens unit has positive optical power, and its object side is convex.

[0006] In some possible embodiments, the sixth lens unit includes a sixth lens having positive optical power, with the object side of the sixth lens being convex and the image side of the sixth lens being convex; wherein the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are spherical lenses; and the sixth lens is an aspherical lens.

[0007] In some possible embodiments, the sixth lens unit includes a first sub-lens and a second sub-lens, and the fifth lens, the first sub-lens, and the second sub-lens are arranged sequentially on the optical axis; the first sub-lens has positive optical power, and the object-side surface of the first sub-lens is convex, and the image-side surface of the first sub-lens is convex; the second sub-lens has positive optical power, and the object-side surface of the second sub-lens is convex, and the image-side surface of the second sub-lens is flat; wherein the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the first sub-lens, and the second sub-lens are spherical lenses.

[0008] In some possible embodiments, the projection lens also includes an aperture stop located between the third lens and the fourth lens.

[0009] In some possible embodiments, the fourth lens and the fifth lens are cemented together.

[0010] In some possible embodiments, the maximum field of view of the projection lens is FOV; wherein FOV satisfies the relationship: FOV≥64°.

[0011] In some possible embodiments, the effective focal length of the first lens is f1, and the effective focal length of the projection lens is f; wherein f1 and f satisfy the relationship: -4.2 <f1 / f<-2.6。

[0012] In some possible embodiments, the radius of curvature of the image-side surface of the second lens is R4, and the radius of curvature of the object-side surface of the third lens is R5; wherein R4 and R5 satisfy the relationship: -4.2 <R4 / R5<-3.9。

[0013] In some possible embodiments, the effective focal length of the third lens is f3, the Abbe number of the third lens is ν3, the effective focal length of the fourth lens is f4, the Abbe number of the fourth lens is ν4, and the effective focal length of the projection lens is f; wherein f3, ν3, f4, ν4 and f satisfy the relationship: -0.021≤f / (f3*ν3)+f / (f4*ν4)<0.

[0014] In some possible embodiments, the edge thickness of the second lens is ET2, and the center thickness of the second lens is CT2; wherein ET2 and CT2 satisfy the relationship: ET2 / CT2≥0.47.

[0015] In some possible embodiments, the edge thickness of the fifth lens is ET5, and the center thickness of the fifth lens is CT5; wherein ET5 and CT5 satisfy the relationship: ET5 / CT5≥0.35.

[0016] According to a second aspect of this application, embodiments of this application also provide a projection device, which includes the aforementioned projection lens and image source. The image source is used to generate a projected image, and the projection lens is used to project the projected image.

[0017] In some possible embodiments, the principal light angle of the image source is CRA; wherein CRA satisfies the relationship: CRA≤1°.

[0018] In some possible embodiments, the distance between the object side of the first lens and the image side of the fourth lens is TTL, and the distance between the image side of the sixth lens unit and the image source is BFL; wherein TTL and BFL satisfy the relationship: BFL / TTL>0.4.

[0019] In some possible embodiments, the entrance pupil diameter of the projection lens is EPD, and half the diagonal length of the light-emitting area of ​​the image source is IMH; wherein, EPD and IMH satisfy the relationship: EPD / IMH≥0.69.

[0020] This application provides a projection lens and a projection device equipped with the projection lens. The projection lens includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens unit arranged sequentially along the optical axis from the object side to the image side. Specifically, the first lens has negative optical power, the second lens has positive optical power, the third lens has negative optical power, the fourth lens has negative optical power, the fifth lens has positive optical power, and the sixth lens unit has positive optical power. Therefore, this application provides a projection lens including at least six lenses. This projection lens can achieve telecentricity of the image side and has the characteristics of miniaturization, low distortion, and high image quality. This is beneficial for achieving miniaturization and improving the image display quality of projection devices equipped with this projection lens (e.g., dynamic welcome lights in vehicles). Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the projection device provided in the embodiments of this application.

[0023] Figure 2 yes Figure 1 A schematic diagram of the structure of the projection lens and image source.

[0024] Figure 3 yes Figure 2 A schematic diagram of the structure of the image source.

[0025] Figure 4 yes Figure 2 A schematic diagram of the principal light angle of the image source.

[0026] Figure 5 yes Figure 1 Another schematic diagram of the projection lens and image source.

[0027] Figure 6 This is a graph showing the astigmatism and distortion of the projection lens provided in the first example of this application.

[0028] Figure 7 This is a magnification chromatic aberration curve of the projection lens provided in the first example of this application.

[0029] Figure 8 This is an on-axis chromatic aberration curve of the projection lens provided in the first example of this application.

[0030] Figure 9 This is a relative illumination curve of the projection lens provided in the first example of this application.

[0031] Figure 10 This is a CRA curve of the projection lens provided in the first example of this application.

[0032] Figure 11 This is a graph showing the astigmatism and distortion of the projection lens provided in the second example of this application.

[0033] Figure 12 This is a magnification chromatic aberration curve of the projection lens provided in the second example of this application.

[0034] Figure 13 This is an on-axis chromatic aberration curve of the projection lens provided in the second example of this application.

[0035] Figure 14 This is a relative illumination curve of the projection lens provided in the second example of this application.

[0036] Figure 15 This is a CRA curve of the projection lens provided in the second example of this application. Detailed Implementation

[0037] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present application without creative effort are within the scope of protection of the present application.

[0038] Please see Figure 1 This application provides a projection lens 100 and a projection device 200 configured with the projection lens 100. The projection device 200 may include an image source 70 and a projection lens 100. The image source 70 can be used to generate a projected image, and the projection lens 100 can be used to project the projected image.

[0039] As an example, the projection device 200 could be a welcome light in a vehicle. The image source 70 can generate the projected image using Digital Light Processing (DLP) technology, and the projection lens 100 can project the image onto the ground or a wall to enhance the passenger experience. Specifically, the welcome light can also be located below the vehicle door, on the side of the vehicle body, etc. In other possible examples, the welcome light can also be integrated into the vehicle's headlights to save installation space.

[0040] Please see Figure 2 The projection lens 100 provided in this embodiment may include a first lens 10, a second lens 20, a third lens 30, a fourth lens 40, a fifth lens 50, and a sixth lens unit 60 arranged sequentially along the optical axis O from the object side to the image side. The first lens 10 has negative optical power, its object-side surface S1 is convex, and its image-side surface S2 is concave. The second lens 20 has positive optical power, its object-side surface S3 is convex, and its image-side surface S4 is convex. The third lens 30 has negative optical power, its object-side surface S5 is convex, and its image-side surface S6 is concave. The fourth lens 40 has negative optical power, its object-side surface S7 is concave, and its image-side surface S8 is concave. The fifth lens 50 has positive optical power, its object-side surface S9 is convex, and its image-side surface S10 is convex. The sixth lens unit 60 has positive optical power, and the object side S11 of the sixth lens unit 60 is convex.

[0041] Specifically, the "sixth lens unit 60" here may include a single lens or multiple lenses. When the sixth lens unit 60 includes multiple lenses, the combined optical power of the multiple lenses is positive, and the "object side surface S11 of the sixth lens unit 60" refers to the object side surface of the lens that has the smallest distance from the fifth lens 50 among the multiple lenses.

[0042] It should be noted that the terms "object side" and "image side" mentioned above should be understood as the relative positional relationship between the projection lens 100 and the environment or image source 70 during application. For example, the "image side" of the projection lens 100 or each lens should be understood as the side where the image source 70 is located, and the "object side" of the projection lens 100 or each lens should be understood as the side where ambient light enters the projection lens 100. Furthermore, when the projection lens 100 is installed in a projection device 200 with an image source 70, the side where the image source 70 is located is the "image side," the sixth lens unit 60 is positioned close to the image side, and the first lens 10 is positioned away from the image side. The projected image generated by the image source 70 is transmitted sequentially to the object side through the sixth lens unit 60, the fifth lens 50, the fourth lens 40, the third lens 30, the second lens 20, and the first lens 10. The "object side" can be the side where ambient light enters the projection lens 100, or it can be the side closer to the target projection area (e.g., the ground or a wall).

[0043] This embodiment provides a projection lens 100 including at least six lenses. The projection lens 100 can achieve the function of image-side telecentricity and has the characteristics of miniaturization, low distortion and high image quality. It is beneficial to achieve miniaturization design and improve the image display quality of the projection device 200 (e.g., a welcome light in a vehicle) equipped with the projection lens 100.

[0044] In this embodiment, image source 70 is used to generate a projected image. Image source 70 can modulate incident light to generate light carrying the projected image and emit the light in a specified direction. Please refer to [link to relevant documentation]. Figure 3 The image source 70 may include a light-emitting region IMA, which emits the light carrying the projected image. This light is transmitted sequentially through a sixth lens unit 60, a fifth lens 50, a fourth lens 40, a third lens 30, a second lens 20, and a first lens 10 on the optical axis O. Of course, the incident light to be modulated also enters the image source 70 through the light-emitting region IMA. Specifically, the light-emitting region IMA can be approximately rectangular. In this embodiment, half the diagonal length of the light-emitting region IMA is denoted as IMH, and the plane containing the light-emitting region IMA is denoted as the image plane.

[0045] Please see Figure 4 In this embodiment, the principal angle of image source 70 is denoted as CRA, that is, CRA is the angle between the incident direction of the principal ray L of the image plane and the direction perpendicular to the image plane. Figure 4In this embodiment, the principal ray L of the image plane is refracted by the projection lens 100 and then incident on the image plane. Specifically, in this embodiment, CRA satisfies the relationship: CRA≤1°. Therefore, when the projection lens 100 in this embodiment is assembled into the projection device 200, it is easy to cooperate with the illumination module (not shown in the figure) in the projection device 200, so that the incident light to be modulated generated by the illumination module can be accurately incident on the light-emitting region IMA of the image source 70, reducing the assembly difficulty of the projection lens 100.

[0046] In this embodiment, the entrance pupil diameter (not shown in the figure) of the projection lens 100 is denoted as EPD, where EPD is the pupil diameter seen from the object space. Specifically, with a fixed focal length of the projection lens 100, EPD and the F-number of the projection lens 100 are inversely proportional. In this embodiment, EPD and IMH satisfy the relationship: EPD / IMH 0.69. Therefore, when the projection lens 100 in this embodiment is assembled into the projection device 200, it is more conducive to the energy matching between the projection lens 100 and the lighting module in the projection device 200, thereby improving the utilization efficiency of light energy.

[0047] In some possible embodiments, the image source 70 can be a Digital Micromirror Device (DMD). The DMD can include a digital micromirror array, where each digital micromirror constitutes a modulation unit. One modulation unit is used to modulate the image corresponding to one pixel. Each digital micromirror is flipped under the drive signal generated by the controller. The number of flips of each digital micromirror is determined by the drive signal. The flipped digital micromirrors are used to modulate the incident light and generate light carrying the projected image. In other possible embodiments, the image source 70 can also be a High-Temperature Poly Silicon (HTPS) LCD display chip, a reflective Liquid Crystal on Silicon (LCOS) LCD, a Micro Light Emitting Diode Display (Micro LED), etc. This embodiment does not limit the specific implementation of the image source 70.

[0048] Please refer to it again. Figure 2 In this embodiment, the projection device 200 may further include a transmissive element 80 and a prism 90, which are sequentially disposed between the sixth lens unit 60 and the image source 70 and located on the optical axis O. Therefore, the light carrying the projected image generated by the image source 70 will sequentially pass through the transmissive element 80 and the prism 90 and enter the sixth lens unit 60.

[0049] Specifically, the transmissive element 80 can be attached to one side of the image source 70 and cover the light-emitting area IMA to protect the light-emitting area IMA. Specifically, the transmissive element 80 can be a cover glass, and the object side S15 and the image side S16 of the cover glass can be flat.

[0050] Prism 90 can guide the incident light to be modulated generated by the illumination module to the image source 70, and guide the light carrying the projected image generated by the image source 70 to the projection lens 100. Specifically, prism 90 can be a polarizing beam splitter (PBS), and the object side S13 and image side S14 of prism 90 can be planes respectively.

[0051] In this embodiment, the lenses are arranged in the following order along the optical axis O from the object side to the image side: first lens 10, second lens 20, third lens 30, fourth lens 40, fifth lens 50, and sixth lens unit 60. The sixth lens unit 60 is closest to the image source 70, while the first lens 10 is furthest from the image source 70. Specifically, each lens may include an object-side side and an image-side side, located on opposite sides of the lens. The image-side side faces the image source 70, while the object-side side faces away from the image source 70. Therefore, the light rays carrying the projected image generated by the image source 70 enter the lens via the image-side side and exit via the object-side side.

[0052] Specifically, in two adjacent lenses, the fourth lens 40 and the fifth lens 50 are cemented together to save installation space in the projection lens 100, achieving a miniaturized and compact design. Furthermore, cementing the fourth lens 40 and the fifth lens 50 can eliminate spherical aberration and chromatic aberration, reduce light loss, and improve image quality and brightness. In addition to the fourth lens 40 and the fifth lens 50, other adjacent lenses can be separated by air gaps. For example, the first lens 10 and the second lens 20 are separated by air gaps, as are the second lens 20 and the third lens 30.

[0053] In this embodiment, the first lens 10 has negative optical power, that is, the first lens 10 can diverge light. The object-side surface S1 of the first lens 10 is convex, and the image-side surface S2 of the first lens 10 is concave.

[0054] Specifically, the effective focal length of the first lens 10 is f1, and the effective focal length of the projection lens is f. Wherein f1 and f satisfy the relational expression: -4.2<f1 / f<-2.6. Therefore, the projection lens 100 in this embodiment can realize reasonable distribution of the negative optical power of the front lens group, which is beneficial to ensuring that the projection lens 100 has a sufficient back focal length.

[0055] In this embodiment, the second lens 20 has positive optical power, that is, the second lens 20 can converge light rays. Wherein, the object side surface S3 of the second lens 20 is a convex surface, and the image side surface S4 of the second lens 20 is a convex surface.

[0056] Specifically, the edge thickness (peripheral thickness) of the second lens 20 is ET2, and the center thickness (central thickness) of the second lens 20 is CT2. Wherein ET2 and CT2 satisfy the relational expression: ET2 / CT2≥0.47. Therefore, the second lens 20 in this embodiment can achieve good correction of the aberration of the projection lens 100, and has good machinability.

[0057] In this embodiment, the third lens 30 has negative optical power, that is, the third lens 30 can diverge light rays. Wherein, the object side surface S5 of the third lens 30 is a convex surface, and the image side surface S6 of the third lens 30 is a concave surface.

[0058] Specifically, the radius of curvature of the image side surface of the second lens 20 is R4, and the radius of curvature of the object side surface of the third lens 30 is R5. Wherein R4 and R5 satisfy the relational expression: -4.2<R4 / R5<-3.9. Therefore, when the second lens 20 and the third lens 30 in this embodiment satisfy the above relational expression, the separation degree of the second lens 20 and the third lens 30 is limited, which is beneficial to reducing the coma of the projection lens 100, improving the imaging definition of the projection lens 100, and improving the image quality (for example, increasing the contrast of the image, reducing color distortion, etc.).

[0059] In this embodiment, the fourth lens 40 has negative optical power, that is, the fourth lens 40 can diverge light rays. The object side surface S7 of the fourth lens 40 is a concave surface, and the image side surface S8 of the fourth lens 40 is a concave surface.

[0060] Specifically, the effective focal length of the third lens 30 is f3, and its Abbe number is ν3; the effective focal length of the fourth lens 40 is f4, and its Abbe number is ν4; and the effective focal length of the projection lens 100 is f. Here, f3, ν3, f4, ν4, and f satisfy the relationship: -0.021 ≤ f / (f3*ν3) + f / (f4*ν4) < 0. Therefore, in this embodiment, the third lens 30 and the fourth lens 40, satisfying the above relationship, are beneficial for correcting the system chromatic aberration of the projection device 200 and improving the image display quality.

[0061] In this embodiment, the fifth lens 50 has positive optical power, that is, the fifth lens 50 can converge light rays. The object-side surface S9 of the fifth lens 50 is convex, and the image-side surface S10 of the fifth lens 50 is also convex.

[0062] Specifically, the edge thickness (side thickness) of the fifth lens 50 is ET5, and the center thickness (middle thickness) of the fifth lens 50 is CT5. ET5 and CT5 satisfy the relationship: ET5 / CT5 ≥ 0.35. Therefore, the fifth lens 50 in this embodiment can effectively correct the aberrations of the projection lens 100 and has good manufacturability.

[0063] In this embodiment, the sixth lens unit 60 has positive optical power, that is, the sixth lens unit 60 can converge light rays. The object-side surface S11 of the sixth lens unit 60 is convex.

[0064] As an example, please refer again. Figure 2 The sixth lens unit 60 may include a sixth lens 610, which has positive optical power. The object-side surface S11 of the sixth lens 610 is convex, and the image-side surface S12 of the sixth lens 610 is also convex. Specifically, the first lens 10, the second lens 20, the third lens 30, the fourth lens 40, and the fifth lens 50 are spherical lenses, and the sixth lens 610 is an aspherical lens.

[0065] Therefore, in Figure 2 In the example shown, the projection lens 100 includes six lenses, enabling a miniaturized design. Furthermore, the inclusion of only one aspherical lens among the six lenses reduces manufacturing costs and improves image display quality of the projection device 200.

[0066] As another example, please refer to Figure 5The sixth lens unit 60 may include a first sub-lens 630 and a second sub-lens 650, and the fifth lens 50, the first sub-lens 630 and the second sub-lens 650 are arranged sequentially on the optical axis O. Therefore, the light rays carrying the projected image generated by the image source 70 will sequentially pass through the second sub-lens 650 and the first sub-lens 630 and then enter the fifth lens 50.

[0067] Specifically, the first sub-lens 630 has positive optical power, meaning it can converge light rays. The object-side surface S11 and image-side surface S112 of the first sub-lens 630 are convex. The second sub-lens 650 has positive optical power, meaning it can converge light rays. The object-side surface S121 of the second sub-lens 650 is convex, and the image-side surface S12 is flat. Specifically, the first lens 10, the second lens 20, the third lens 30, the fourth lens 40, the fifth lens 50, the first sub-lens 630, and the second sub-lens 650 are spherical lenses.

[0068] Therefore, in Figure 5 In the example shown, the projection lens 100 includes seven lenses, all of which are spherical lenses. That is to say, Figure 5 The projection lens 100 in the middle adopts a global surface lens architecture, compared to Figure 2 The example shown eliminates the need for an aspherical lens, which further reduces the manufacturing cost of the projection lens 100.

[0069] Please refer to it again. Figure 2 and Figure 5 The distance between the object-side surface S1 of the first lens 10 and the image-side surface S8 of the fourth lens 40 is TTL, and the distance between the image-side surface S12 of the sixth lens unit 60 and the image source is BFL. TTL and BFL satisfy the relationship: BFL / TTL > 0.4.

[0070] It should be noted that, in Figure 2 In the example shown, when the sixth lens unit 60 includes a single lens, the object-side surface S11 of the sixth lens 610 is the same as the object-side surface S11 of the sixth lens unit 60, and the image-side surface S12 of the sixth lens 610 is the same as the image-side surface S12 of the sixth lens unit 60. Figure 5 In the example shown, when the sixth lens unit 60 includes multiple sub-lenses, the object-side surface S11 of the first sub-lens 630 is the object-side surface S11 of the sixth lens unit 60, and the image-side surface S12 of the second sub-lens 650 is the image-side surface S12 of the sixth lens unit 60.

[0071] Therefore, the projection lens 100 in this embodiment has the advantage of a longer back focal length, which is more conducive to the adaptation of the projection lens 100 and the lighting module in the projection device 200, and improves the utilization efficiency of light energy.

[0072] Please refer to it again. Figure 2 and Figure 5 The projection lens 100 may also include an aperture stop STO, which is located between the third lens 30 and the fourth lens 40. The aperture stop STO is used to block stray light in the light and improve the sharpness and contrast of the image. Specifically, the aperture stop STO may be an aperture stop or a field stop, etc.

[0073] It is not difficult to see here that in this embodiment, the aperture stop STO is positioned in the middle of the multiple lenses. Figure 2 The corresponding "three in front, three in back" architecture can balance the intensity of light and image quality while reducing the impact of aberrations.

[0074] Furthermore, in this embodiment, the maximum field of view (FOV) of the projection lens 100 is defined. On one hand, when the first lens 10, second lens 20, third lens 30, fourth lens 40, fifth lens 50, and sixth lens unit 60 all satisfy the aforementioned optical power and surface shape conditions, it facilitates a reasonable allocation of the optical power of the projection lens 100, makes optical balance of the projection lens 100 easier, and allows for the correction of various aberrations. On the other hand, in this embodiment, the FOV satisfies the relationship: FOV ≥ 64°, which helps the projection lens 100 meet the field of view requirements and ensures that the projection field of view of the projection lens 100 is sufficiently large.

[0075] Please refer to Table-1, which shows the basic parameters of the projection device 200 provided in the first example of this application. This first example corresponds to... Figure 2 The projection lens 100 shown.

[0076] Table 1 The units for radius of curvature, thickness, and half-aperture are all millimeters (mm). In each cell of the material column, the first parameter is the refractive index of the corresponding lens, and the second parameter is the dispersion coefficient. For example, 1.77 and 49.6 indicate that the refractive index of the first lens 10 is 1.77, and the dispersion coefficient is 49.6.

[0077] Please refer to Table-2, which shows the surface coefficients of the aspherical lens (i.e., the sixth lens 610) provided in the first example of this application.

[0078] Table 2 Please refer to Table-3, which shows the optical parameters of the projection device 200 provided in the first example of this application.

[0079] Table 3 Specifically, in the first example, the IMH is 2.56mm, the FOV is 64°, and the f is 4.23mm. Furthermore, the F-number (Fno) of the projection lens 100 is 2.4.

[0080] Please see Figure 6 , Figure 6 The diagram shows the astigmatism and distortion curves of the projection lens 100 provided in the first example of this application. Figure 6 The left side shows the field curvature, where the three T lines represent the meridional image plane curvature at wavelengths of 625nm, 520nm, and 450nm, respectively, and the three S lines represent the sagittal image plane curvature at wavelengths of 625nm, 520nm, and 450nm, respectively. Figure 6 The right side shows the distortion curve, which represents the magnitude of distortion at different image heights. From Figure 6 It is easy to see that the focus offset is less than 0.7mm and the optical distortion is less than 4%. Therefore, the image projected by the projection lens 100 provided in the first example has a low degree of distortion.

[0081] Please see Figure 7 , Figure 7 A magnification chromatic aberration curve of the projection lens 100 provided in the first example of this application is shown. The magnification chromatic aberration curve represents the magnitude of chromatic aberration corresponding to different image heights; the red line corresponds to a wavelength of 450nm, the green line to a wavelength of 520nm, and the blue line to a wavelength of 625nm. From... Figure 7 It is easy to see that the magnification color difference is less than 5µm. Therefore, the image projected by the projection lens 100 provided in the first example has high clarity.

[0082] Please see Figure 8 , Figure 8 An on-axis chromatic aberration curve of the projection lens 100 provided in the first example of this application is shown. The on-axis chromatic aberration curve represents the magnitude of chromatic aberration corresponding to different apertures in the central field of view; the red line corresponds to a wavelength of 450 nm, the green line to a wavelength of 520 nm, and the blue line to a wavelength of 625 nm. From... Figure 7 and Figure 8 It is easy to see that the color difference of the projection lens 100 is small. Therefore, the lines in the image projected by the projection lens 100 will not have obvious color edges, and there will be no obvious color diffusion spots in the center of the image.

[0083] Please see Figure 9 , Figure 9The diagram shows the relative illumination curve of the projection lens 100 provided in the first example of this application. The relative illumination curve represents the ratio of the imaging brightness at different viewing positions to the imaging brightness of the central viewing field. Figure 9 It is not difficult to see that the relative illumination is greater than 0.82.

[0084] Please see Figure 10 , Figure 10 The diagram shows the CRA curve of the projection lens 100 provided in the first example of this application. The CRA curve represents the magnitude of the incident angle in degree corresponding to different image heights. The blue line corresponds to the lower beam angle, the green line corresponds to the chief beam angle, and the red line corresponds to the upper beam angle.

[0085] In summary, from Figures 6 to 10 As can be easily seen from the curves shown, the projection lens 100 provided in the first example of this application has good projection performance.

[0086] Please refer to Table-4, which shows the basic parameters of the projection device 200 provided in the second example of this application. This second example corresponds to... Figure 5 The projection lens 100 shown.

[0087] Table 4 The units for radius of curvature, thickness, and half-aperture are all millimeters (mm). In each cell of the material column, the first parameter is the refractive index of the corresponding lens, and the second parameter is the dispersion coefficient. For example, 1.77 and 49.6 indicate that the refractive index of the first lens 10 is 1.77, and the dispersion coefficient is 49.6.

[0088] Please refer to Table-5, which shows the optical parameters of the projection device 200 provided in the second example of this application.

[0089] Table 5 Specifically, in the second example, the IMH is 2.56mm, the FOV is 64°, and the f is 4.25mm. Furthermore, the F-number (Fno) of the projection lens 100 is 2.4.

[0090] Please see Figure 11 , Figure 11 The diagram shows the astigmatism and distortion curves of the projection lens 100 provided in the second example of this application. Figure 11The left side shows the field curvature, where the three T lines represent the meridional image plane curvature at wavelengths of 625nm, 520nm, and 450nm, respectively, and the three S lines represent the sagittal image plane curvature at wavelengths of 625nm, 520nm, and 450nm, respectively. Figure 11 The right side shows the distortion curve, which represents the magnitude of distortion at different image heights. From Figure 11 It is easy to see that the focus offset is less than 0.9mm and the optical distortion is less than 4%. Therefore, the image projected by the projection lens 100 provided in the second example has a small degree of distortion.

[0091] Please see Figure 12 , Figure 12 A magnification chromatic aberration curve of the projection lens 100 provided in the second example of this application is shown. The magnification chromatic aberration curve represents the magnitude of chromatic aberration corresponding to different image heights; the red line corresponds to a wavelength of 450nm, the green line to a wavelength of 520nm, and the blue line to a wavelength of 625nm. From... Figure 12 It is easy to see that the magnification color difference is less than 5µm. Therefore, the image projected by the projection lens 100 provided in the second example has high clarity.

[0092] Please see Figure 13 , Figure 13 An on-axis chromatic aberration curve of the projection lens 100 provided in the second example of this application is shown. The on-axis chromatic aberration curve represents the magnitude of chromatic aberration corresponding to different apertures in the central field of view; the red line corresponds to a wavelength of 450 nm, the green line to a wavelength of 520 nm, and the blue line to a wavelength of 625 nm. From... Figure 12 and Figure 13 It is easy to see that the color difference of the projection device 200 is small. Therefore, the lines of the image projected by the projection device 200 will not have obvious color edges, and there will be no obvious color diffusion spots in the center of the image.

[0093] Please see Figure 14 , Figure 14 The diagram shows the relative illumination curve of the projection lens 100 provided in the second example of this application. The relative illumination curve represents the ratio of the imaging brightness at different viewing positions to the imaging brightness of the central viewing field. Figure 14 It is not difficult to see that the relative illumination is greater than 0.92.

[0094] Please see Figure 15 , Figure 15The diagram shows the CRA curve of the projection lens 100 provided in the second example of this application. The CRA curve represents the magnitude of the incident angle in degree corresponding to different image heights. The blue line corresponds to the lower beam angle, the green line corresponds to the chief beam angle, and the red line corresponds to the upper beam angle.

[0095] In summary, from Figures 11 to 15 As can be easily seen from the curves shown, the projection lens 100 provided in the second example of this application has good projection performance.

[0096] It should be noted that in the first and second examples, the image plane size is the same, and the first lens 10, the second lens 20, the third lens 30, the fourth lens 40, and the fifth lens 50 can be made of the same material.

[0097] This application provides a projection lens 100 and a projection device 200 equipped with the projection lens 100. The projection lens 100 may include a first lens 10, a second lens 20, a third lens 30, a fourth lens 40, a fifth lens 50, and a sixth lens unit 60 arranged sequentially along the optical axis O from the object side to the image side. The first lens 10 has negative optical power, its object-side surface S1 is convex, and its image-side surface S2 is concave. The second lens 20 has positive optical power, its object-side surface S3 is convex, and its image-side surface S4 is convex. The third lens 30 has negative optical power, its object-side surface S5 is convex, and its image-side surface S6 is concave. The fourth lens 40 has negative optical power, its object-side surface S7 is concave, and its image-side surface S8 is concave. The fifth lens 50 has positive optical power, and its object-side surface S9 and image-side surface S10 are both convex. The sixth lens unit 60 has positive optical power, and its object-side surface S11 is also convex.

[0098] This embodiment provides a projection lens 100 including at least six lenses. The projection lens 100 can achieve the function of image-side telecentricity and has the characteristics of miniaturization, low distortion and high image quality. It is beneficial to achieve miniaturization design and improve the image display quality of the projection device 200 (e.g., a welcome light in a vehicle) equipped with the projection lens 100.

[0099] In this application specification, certain terms are used to refer to specific components. Those skilled in the art will understand that hardware manufacturers may use different names to refer to the same component. The specification and claims do not distinguish components based on differences in name, but rather on differences in function. The term "comprising" throughout the specification and claims is an open-ended term and should be interpreted as "including but not limited to"; "generally" means that those skilled in the art can solve the technical problem within a certain margin of error and basically achieve the technical effect.

[0100] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "inside", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the purpose of simplifying the description of this application and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0101] In this application, unless otherwise expressly specified or limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or merely surface contact. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0102] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0103] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A projection lens, characterized in that, It includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens unit arranged sequentially along the optical axis from the object side to the image side; The first lens has negative optical power, the object side of the first lens is convex, and the image side of the first lens is concave. The second lens has positive optical power, the object side of the second lens is convex, and the image side of the second lens is convex. The third lens has negative optical power, the object side of the third lens is convex, and the image side of the third lens is concave. The fourth lens has negative optical power, the object side of the fourth lens is concave, and the image side of the fourth lens is concave. The fifth lens has positive optical power, the object side of the fifth lens is convex, and the image side of the fifth lens is convex. The sixth lens unit has positive optical power, and the object side of the sixth lens unit is convex.

2. The projection lens according to claim 1, characterized in that, The sixth lens unit includes a sixth lens, which has positive optical power, and the object side and image side of the sixth lens are both convex. The first lens, the second lens, the third lens, the fourth lens, and the fifth lens are spherical lenses; the sixth lens is an aspherical lens.

3. The projection lens according to claim 1, characterized in that, The sixth lens unit includes a first sub-lens and a second sub-lens, and the fifth lens, the first sub-lens and the second sub-lens are arranged sequentially on the optical axis; The first sub-lens has positive optical power, the object side of the first sub-lens is convex, and the image side of the first sub-lens is convex. The second sub-lens has positive optical power, the object side of the second sub-lens is convex, and the image side of the second sub-lens is flat. Among them, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the first sub-lens, and the second sub-lens are spherical lenses.

4. The projection lens according to claim 1, characterized in that, The projection lens also includes an aperture stop, which is located between the third lens and the fourth lens.

5. The projection lens according to claim 1, characterized in that, The fourth lens and the fifth lens are glued together.

6. The projection lens according to any one of claims 1 to 5, characterized in that, The maximum field of view of the projection lens is FOV; wherein, the FOV satisfies the following relationship: FOV≥64 .

7. The projection lens according to any one of claims 1 to 5, characterized in that, The effective focal length of the first lens is f1, and the effective focal length of the projection lens is f; wherein f1 and f satisfy the relationship: -4.2 <f1 / f<-2.6。 8. The projection lens according to any one of claims 1 to 5, characterized in that, The image-side surface of the second lens has a radius of curvature of R4, and the object-side surface of the third lens has a radius of curvature of R5; wherein R4 and R5 satisfy the relationship: -4.2 <R4 / R5<-3.9。 9. The projection lens according to any one of claims 1 to 5, characterized in that, The effective focal length of the third lens is f3, the Abbe number of the third lens is ν3, the effective focal length of the fourth lens is f4, the Abbe number of the fourth lens is ν4, and the effective focal length of the projection lens is f; wherein, f3, ν3, f4, ν4 and f satisfy the relationship: -0.021≤f / (f3*ν3)+f / (f4*ν4)<0.

10. The projection lens according to any one of claims 1 to 5, characterized in that, The edge thickness of the second lens is ET2, and the center thickness of the second lens is CT2; wherein, ET2 and CT2 satisfy the relationship: ET2 / CT2≥0.

47.

11. The projection lens according to any one of claims 1 to 5, characterized in that, The edge thickness of the fifth lens is ET5, and the center thickness of the fifth lens is CT5; wherein, ET5 and CT5 satisfy the relationship: ET5 / CT5≥0.

35.

12. A projection device, characterized in that, Includes the projection lens and image source as described in any one of claims 1 to 11; The image source is used to generate the projected image; The projection lens is used to project the projected image.

13. The projection device according to claim 12, characterized in that, The principal angle of the image source is CRA; wherein, CRA satisfies the following relationship: CRA≤1 .

14. The projection device according to claim 12, characterized in that, The distance between the object-side surface of the first lens and the image-side surface of the fourth lens is TTL, and the distance between the image-side surface of the sixth lens unit and the image source is BFL; wherein, TTL and BFL satisfy the relationship: BFL / TTL>0.

4.

15. The projection device according to claim 12, characterized in that, The entrance pupil diameter of the projection lens is EPD, and half the diagonal length of the light-emitting area of ​​the image source is IMH; wherein, EPD and IMH satisfy the relationship: EPD / IMH≥0.69.

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