Projection lens and projection system, automobile

Abstract

Embodiments of the present application provide a projection lens, a projection system and a car, and relate to the technical field of optical imaging, and are used for a projection system suitable for a small target surface. The projection lens (100) comprises, in the direction of the optical axis, a first lens (110) with optical power, a second lens (210) with negative optical power and a third lens (310) with positive optical power arranged in sequence from the object side to the image side. The image side of the second lens (210) and the object side of the third lens (310) are attached. Wherein the focal length f1 of the first lens (110), the focal length f2 of the second lens (210), the focal length f3 of the third lens (310), the combined focal length f23 of the second lens (210) and the third lens (310) and the effective focal length EFL of the projection lens (100) satisfy at least one of |f1 / EFL|≥10, 1.7≤|f2 / f3|≤3.7 or 0.8≤|f23 / EFL|≤1.5.

Description

Technical Field

[0001] This application relates to the field of optical imaging technology, and in particular to a projection lens and projection system, and an automobile. Background Technology

[0002] With the development of automotive technology in areas such as autonomous driving and human-vehicle interaction, people have increasingly higher requirements for car configurations, demanding greater functionality, comfort, and entertainment features. Intelligent headlights, as a key indicator of automotive intelligence, are playing an increasingly important role in this development, enabling people to enjoy entertainment anytime, anywhere through automotive projection technology.

[0003] Existing projection systems have large, expensive, and complex projection lenses, making them more suitable for projection systems with large target surfaces. Summary of the Invention

[0004] This application provides a projection lens and projection system, and an automobile, for use with a projection system adapted to a small target surface.

[0005] To achieve the above objectives, this application adopts the following technical solution:

[0006] A first aspect of this application provides a projection lens, comprising: a first lens having optical power, a second lens having negative optical power, and a third lens having positive optical power, arranged sequentially from the object side to the image side along the optical axis. The image side of the second lens is attached to the object side of the third lens. The focal length f1 of the first lens, the focal length f2 of the second lens, the focal length f3 of the third lens, the combined focal length f23 of the second and third lenses, and the effective focal length EFL of the projection lens satisfy at least one of: |f1 / EFL|≥10, 1.7≤|f2 / f3|≤3.7, or 0.8≤|f23 / EFL|≤1.5.

[0007] The projection lens provided in this application embodiment is arranged in a specific order along the optical axis, from the object side to the image side, with a first lens having optical power, a second lens having negative optical power, and a third lens having positive optical power. Through the cooperation of these lenses, the projection lens satisfies at least one of the following: the focal length f1 of the first lens, the focal length f2 of the second lens, the focal length f3 of the third lens, the combined focal length f23 of the second and third lenses, and the effective focal length EFL of the projection lens. This facilitates control of the light refraction angle, balances aberrations, improves the imaging quality of the projection lens, and enables a large aperture design. Therefore, the projection lens provided in this application embodiment can achieve a projection lens with characteristics such as small target surface, low cost, large aperture, small size, and high resolution, and the projected image brightness is uniform, achieving clear projection at the megapixel level.

[0008] In one possible implementation, the first lens has positive optical power. This facilitates the convergence of light rays.

[0009] In one possible implementation, the first lens is a meniscus lens; the second lens is a meniscus lens; and the third lens is a biconvex lens.

[0010] In one possible implementation, the object-side surface of the first lens is concave, and the image-side surface is convex. The object-side surface of the second lens is convex, and the image-side surface is concave. The image-side surface of the third lens is convex. This results in better imaging and improved image quality.

[0011] In one possible implementation, the first lens is a plastic lens; the second and third lenses are glass lenses. Plastic lenses reduce costs, while glass lenses improve reliability. Using a combination of glass and plastic lenses also corrects the temperature drift of the projection lens, thereby reducing temperature drift in any operating environment and achieving good optical imaging results.

[0012] In one possible implementation, the second and third lenses form a cemented lens. This allows for effective suppression of chromatic aberration in the projection lens through the interplay of the lenses, resulting in better imaging performance.

[0013] In one possible implementation, both the object-side and image-side surfaces of the first lens are aspherical. This increases the design freedom of the projection lens and improves the imaging effect.

[0014] In one possible implementation, both the object-side and image-side surfaces of the second and third lenses are spherical. This would reduce the cost of the projection lens.

[0015] In one possible implementation, the Abbe number vd1 of the first lens satisfies: vd1 ≥ 52. This reduces spherical aberration caused by a large aperture, thereby improving the resolution of the projection lens.

[0016] In one possible implementation, the Abbe number vd2 of the second lens and the Abbe number vd3 of the third lens satisfy: vd3 / vd2≥2. This reduces spherical aberration caused by a large aperture, thereby improving the resolution of the projection lens.

[0017] In one possible implementation, the total optical length (TTL) of the projection lens and the effective focal length (EFL) of the projection lens satisfy the condition: 1.5 ≤ TTL / EFL ≤ 2.5. This allows for a small-sized projection lens.

[0018] In one possible implementation, the back focal length (BFL) of the projection lens and the effective focal length (EFL) of the projection lens satisfy the condition: 0.5 ≤ BFL / EFL ≤ 1.5. This allows for a long back focal length in the projection lens.

[0019] A second aspect of this application provides a projection system, including: a light source, a light valve modulation component, and a projection lens as described in any of the first aspects; the light valve modulation component is located on the light-emitting side of the light source and is used to modulate and reflect incident light; the projection lens is located on the reflected light path of the light valve modulation component and is used to image the emitted light from the light valve modulation component.

[0020] The projection system provided in the second aspect of the embodiments of this application includes the projection lens of any one of the first aspects, and its beneficial effects are the same as those of the projection lens, which will not be repeated here.

[0021] A third aspect of this application provides an automobile, including: a projection system and a processing unit as described in the second aspect; the processing unit is used to control the projection system.

[0022] The automobile provided in the third aspect of the embodiments of this application includes the projection system of any one of the second aspects, and its beneficial effects are the same as those of the projection system, which will not be repeated here. Attached Figure Description

[0023] Figure 1 A schematic diagram of the structure of a car provided in an embodiment of this application;

[0024] Figure 2 This is a schematic diagram of the structure of a projection system provided in an embodiment of this application;

[0025] Figure 3 This is a schematic diagram of the structure of a projection lens provided in an embodiment of this application;

[0026] Figure 4A for Figure 3 The modulation transfer function curve of the projection lens at room temperature is shown below.

[0027] Figure 4B for Figure 3 The modulation transfer function curve of the projection lens at low temperature is shown below.

[0028] Figure 4C for Figure 3 The modulation transfer function curve of the projection lens at high temperature is shown below;

[0029] Figure 4D for Figure 3 The field curvature curve of the projection lens is shown.

[0030] Figure 4E for Figure 3 The distortion curve of the projection lens is shown.

[0031] Figure 4F for Figure 3 The relative illumination curve of the projection lens is shown.

[0032] Figure 4G for Figure 3 The defocus modulation transfer function curve of the projection lens is shown below;

[0033] Figure 5A for Figure 3 The modulation transfer function curve of the projection lens at room temperature is shown below.

[0034] Figure 5B for Figure 3 The modulation transfer function curve of the projection lens at low temperature is shown below.

[0035] Figure 5C for Figure 3 The modulation transfer function curve of the projection lens at high temperature is shown below;

[0036] Figure 5D for Figure 3 The field curvature curve of the projection lens is shown.

[0037] Figure 5E for Figure 3 The distortion curve of the projection lens is shown.

[0038] Figure 5F for Figure 3 The relative illumination curve of the projection lens is shown.

[0039] Figure 5G for Figure 3 The diagram shows the defocus modulation transfer function curve of the projection lens. Attached Figure Description

[0041] 1-Automobile; 2-Engine; 3-Electrical equipment; 4-Chassis; 5-Body; 10-Projection system; 100-Projection lens; 200-Light source; 300-Light valve modulation component; 110-First lens; 210-Second lens; 310-Third lens; 410-Aperture. Detailed Implementation

[0042] The technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0043] Hereinafter, the terms "second," "first," etc., are used for descriptive convenience only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "second," "first," etc., may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0044] Furthermore, in the embodiments of this application, directional terms such as "upper," "lower," "left," and "right" may be defined relative to the orientation in which the components are schematically placed in the accompanying drawings. It should be understood that these directional terms can be relative concepts, used for relative description and clarification, and can change accordingly based on the orientation of the components in the accompanying drawings.

[0045] In the embodiments of this application, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a direct connection or an indirect connection through an intermediate medium.

[0046] In this embodiment of the application, "and / or" describes the relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following associated objects have an "or" relationship.

[0047] To facilitate understanding of the technical solutions, the technical terms used in this application are explained below.

[0048] Image side and object side: These are the areas through which imaging rays pass. Imaging rays include the chief ray and the marginal ray. The image side is the surface facing the image, and the object side is the surface facing the object.

[0049] Optical power: equal to the difference between the image-side beam convergence and the object-side beam convergence, characterizing the refractive power of an optical system for an incident parallel beam of light. Optical power is generally expressed in... express, The higher the value, the more the parallel beam of light is refracted. At that time, bending is convergent; At that time, the bending is divergent. When the refraction occurs, it is called plane refraction, which means that the axially parallel beam remains axially parallel after refraction and no bending phenomenon occurs.

[0050] Lens thickness: The thickness of a lens along its optical axis is called the thickness of the lens.

[0051] Total track length (TTL): The total track length is the length along the optical axis from the object-side surface of the first optical element facing the object in the lens to the image plane. It is the total length from the lens barrel head to the image plane and is a major factor in determining the camera's height. The total track length is used to characterize the lens's dimensions.

[0052] Aperture stop: This is a device used to control the amount of light passing through the lens and entering the sensor inside the camera body. The aperture number (F#) is a relative value obtained by dividing the lens's focal length by its aperture diameter (the reciprocal of the relative aperture). A smaller F# value allows more light to enter the lens in the same unit of time, resulting in better lens performance in low-light conditions. A larger F# value results in a shallower depth of field, blurring the background in the photo.

[0053] Focal length (f), 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 imaging plane when a scene at infinity is formed into a clear image on the imaging plane.

[0054] Effective focal length (EFL): The distance between the rear principal plane of a lens or lens group and the image plane. For thin lenses, the focal length is the distance from the center of the lens to the image plane; for thick lenses or lens groups, the focal length is equal to the effective focal length.

[0055] Back focal length (BFL): also known as back focal distance, refers to the distance from the lens closest to the image side of the lens or lens group to the imaging plane of the optical lens.

[0056] Temperature coefficient of refractive index (DN / DT): refers to the relationship between refractive index and temperature.

[0057] Positive focal length: A lens or lens group has a positive focal length and the effect of converging light.

[0058] Negative focal length: A lens or lens group has a negative focal length and has the effect of diverging light.

[0059] Abbe number: also known as dispersion coefficient, refers to the ratio of the difference in refractive index of an optical material at different wavelengths, indicating the degree of dispersion of the material.

[0060] Chief ray: The ray that passes through the center of the lens's entrance pupil and exit pupil.

[0061] Chief ray angle (CRA): The angle at which the chief ray is incident on the image plane, that is, the angle at which the ray passing through the center of the lens's entrance pupil and exit pupil is incident on the image plane.

[0062] Temperature drift: The amount by which the optimal image plane of a lens shifts from its optimal image plane at a certain temperature to that at room temperature, i.e., how the shape, size, and refractive index of the lens surface change with temperature.

[0063] Modulation transfer function (MTF): A metric for evaluating the image quality of a lens.

[0064] Image height (IH): The height of the image formed by the lens.

[0065] Field of view (FOV): In optical instruments, the field of view is the angle between the two edges of the lens, representing the maximum range through which the image of the target object can pass through the lens. The size of the field of view determines the field of view of the optical instrument; the larger the field of view, the larger the field of view, and the smaller the optical magnification.

[0066] The optical axis is a line that passes perpendicularly through the center of an ideal lens. When rays parallel to the optical axis enter a convex lens, an ideal convex lens should have all rays converging at a single point behind the lens; this point of convergence is the focal point.

[0067] Distortion, also known as image distortion, refers to the degree of distortion in the image formed by an optical system relative to the object itself. Distortion occurs due to the spherical aberration of the aperture. The height of the intersection point between the principal ray from different fields of view and the Gaussian image plane is not equal to the ideal image height; this difference is the distortion. Therefore, distortion only changes the imaging position of an off-axis object point on the ideal plane, causing a distortion in the image shape, but it does not affect the image's sharpness.

[0068] The technical solutions in the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0069] This application provides an automobile, which may be a sedan, SUV, bus, or truck, etc., and this application does not limit the type of vehicle.

[0070] Example of a car structure, such as Figure 1 As shown, automobile 1 mainly includes engine 2, electrical equipment 3, chassis 4, and body 5.

[0071] Engine 2 is the power unit of automobile 1. Engine 2 includes engine block, crankshaft and connecting rod mechanism, valve train, cooling system, lubrication system, fuel system, and ignition system (diesel engines do not have an ignition system).

[0072] Electrical equipment 3 includes a battery, generator, regulator, starter, instruments, lights, audio equipment, and windshield wipers.

[0073] The chassis 4 supports and mounts components such as the engine 2 and electrical equipment 3 to form the overall structure of the vehicle 1, and receives power from the engine 2 to enable the vehicle 1 to move and ensure normal driving. The chassis 4 includes the transmission system, running system, steering system, and braking system.

[0074] The body 5 is mounted on the chassis 4 frame and is used for driver and passenger seating or for loading cargo. The car body is generally a unibody structure. The primary function of the car body is to protect the driver and provide a good aerodynamic environment.

[0075] Nowadays, with the development of automotive technology in areas such as autonomous driving and human-vehicle interaction, people have increasingly higher requirements for car configurations, demanding greater functionality, comfort, and entertainment. Intelligent headlights, as an important indicator of automotive intelligence, are playing an increasingly important role in the development of automotive intelligence, enabling people to enjoy entertainment anytime, anywhere through automotive projection technology.

[0076] Traditional car lights use halogen lamps as the light source. Halogen lamps have a simple structure, but their brightness and illumination range cannot be precisely controlled.

[0077] Matrix light-emitting diode (LED) light sources have a certain level of illumination brightness and a certain degree of control over the illumination range.

[0078] However, as an entry-level smart light, matrix LED light sources can only reach a hundred-level LED count (pixel count), which cannot achieve more precise control over lighting brightness and range, has poor anti-glare effect, and cannot realize smart projection.

[0079] The pixel-level headlights used in automotive projection technology control the switching on and off of each pixel unit through a digital micromirror device (DMD) chip, achieving precise lighting brightness and range.

[0080] This application provides a projection system that can be applied to various projection scenarios, including indoors, outdoors, and on roads; it can also be applied to the field of projection imaging; and it can be applied to devices such as projectors, projection lamps, and head-up displays (HUDs). This application does not limit the scope of the application.

[0081] Currently, existing projection systems are based on digital light processing (DLP) architecture, with the DMD chip as the core component. The light emitted from the projection light source is incident on the DMD chip to generate an image, and then the light emitted from the image generated by the DMD chip is incident on the projection lens, which then forms an image, which is finally received by the projection screen.

[0082] A projection system mainly consists of an illumination optical path and a projection lens. The illumination optical path affects the system's energy efficiency and output, while the projection lens affects the projection image quality, such as contrast and sharpness. A DLP (Digital Micromirror Display) connects the illumination optical path and the projection lens.

[0083] Example of a projection system, such as Figure 2 As shown, the projection system 10 mainly includes a projection lens 100, a light source 200, and a light valve modulation component 300.

[0084] Light source 200 is the aforementioned projection light source. Light source 200 can be a laser light source, or it can also be a headlight from vehicle 1. It is understood that when light source 200 is a headlight from vehicle 1, vehicle 1 also includes a processing unit (…). Figure 1 (Not shown in the image), the processing unit is used to control the projection system 10.

[0085] The light valve modulation component 300, located on the light-emitting side of the light source 200, is used to modulate and reflect the incident light. The aforementioned DMD chip is integrated within the light valve modulation component 300.

[0086] The projection lens 100 is located on the reflected light path of the light valve modulation component 300 and is used to image the emitted light of the light valve modulation component 300.

[0087] To improve the energy efficiency and output power of the projection system 10, that is, to increase the luminous flux of the projection system 10, this can be achieved by using a large aperture projection lens 100 or by using a high-power light source 200.

[0088] A projection lens 100 with a large aperture, achieved through reasonable optical design, can improve transmission efficiency and resolution, thereby increasing light throughput. However, designing a large-aperture projection lens 100 is challenging and difficult to implement.

[0089] In addition, high-power light sources can be used to improve energy utilization and output power, thereby increasing luminous flux. However, the power density of LED-based vehicle lights is relatively low. To ensure sufficient output power, a larger light-emitting area is required, which necessitates a projection system 10 with a larger target surface and a more complex and larger projection lens 100 architecture.

[0090] Based on this, the projection system 10 provided in this application embodiment uses a laser as the light source 200. The laser light source enables the projection system 10 to have the characteristics of high energy efficiency, small size, good directionality and long illumination distance. At the same time, since the target surface required for the same light flux produced by the laser light source and the ordinary light source is relatively small, it can be adapted to the simple structure and small size of the projection lens 100, thereby reducing the cost of the projection lens 100.

[0091] Based on this, in order to reduce the cost of the projection lens 100, this application provides a projection lens, which is a three-element projection lens with three lenses.

[0092] like Figure 3 As shown, the projection lens 100 includes a first lens 110, a second lens 210, and a third lens 310 arranged sequentially from the object side to the image side along the optical axis.

[0093] In this embodiment, the lenses are coaxially arranged.

[0094] It should be clarified here that, in actual situations, the optical axes of the lenses may be slightly misaligned due to assembly reasons or lens manufacturing process. In this case, the lenses can still be considered as coaxially arranged.

[0095] Each lens includes an object-side surface facing the object side and an image-side surface facing the image side.

[0096] It is understood that the lenses in the embodiments of this application are all lenses with positive or negative optical power. When a plane mirror is inserted between multiple lenses, the plane mirror is not considered as a lens of the projection lens of this application. For example, when a plane mirror is placed between the first lens 110 and the second lens 210, the plane mirror cannot be considered as the second lens in the embodiments of this application.

[0097] The first lens 110 has optical power.

[0098] For example, the first lens 110 has positive optical power. That is, the first lens 110 has the function of converging light rays.

[0099] In some embodiments, such as Figure 3 As shown, the object-side surface S1 of the first lens 110 can be concave, and the image-side surface S2 of the first lens 110 can be convex.

[0100] In other words, the first lens 110 is a meniscus lens with optical power.

[0101] It is understood that the object-side surface S1 of the first lens 110 can be any of a convex surface, a concave surface, or a plane, and the image-side surface S2 of the first lens 110 can also be any of a convex surface, a concave surface, or a plane. This application embodiment does not limit this, as long as the first lens 110 has optical power.

[0102] It should be clarified here that the convex or concave surfaces mentioned in the embodiments of this application refer to those that are convex or concave near the optical axis. It should be noted that "convex or concave near the optical axis" refers to whether the surface is convex or concave at a position infinitely close to the optical axis of the lens. That is, "paraxial" refers to a position infinitely close to the optical axis. It should also be noted that the shape of the lens and the degree of convexity / concavity of the object-side and image-side surfaces are merely illustrative and do not impose any limitations on the embodiments of this application. The embodiments of this application do not impose any limitations on the convexity / concavity of the portions of the object-side and image-side surfaces away from the optical axis.

[0103] In this case, both the object-side surface S1 and the image-side surface S2 of the first lens 110 are aspherical.

[0104] Furthermore, since the first lens 110 is far from the light source 200, it is less affected by temperature. Therefore, the first lens 110 is made of plastic to reduce costs. In other words, the first lens 110 is a plastic aspherical lens.

[0105] In this way, the plastic aspherical lens can reduce the cost of the projection lens 100 and also has good formability. In addition, the aspherical lens can increase the design freedom of the projection lens 100 and improve the imaging effect.

[0106] In the projection lens 100 provided in this embodiment, the first lens 110 is made of a low-dispersion material. This reduces spherical aberration caused by a large aperture and improves the resolution of the projection lens 100. In other words, the dispersion coefficient (also known as the Abbe number vd) of the material of the first lens 110 is low.

[0107] For example, the Abbe number vd1 of the first lens 110 satisfies: vd1≥52.

[0108] In this embodiment, the second lens 210 has negative optical power, and the third lens 310 has positive optical power. That is, the second lens 210 disperses light, and the third lens 310 converges light.

[0109] In this configuration, the image-side surface of the second lens 210 is bonded to the object-side surface of the third lens 310. For example, the second lens 210 and the third lens 310 form a cemented lens. This effectively suppresses optical chromatic aberration in the projection lens 100, thereby enabling the projection lens 100 to achieve better imaging results.

[0110] like Figure 3 As shown, the object-side surface S3 of the second lens 210 is convex, and the image-side surface S4 of the second lens 210 is concave. This improves the imaging effect and image quality of the projection lens 100.

[0111] In other words, the second lens 210 is a meniscus lens with negative optical power.

[0112] It is understood that the object-side surface S3 of the second lens 210 can be any of a convex surface, a concave surface, or a plane, and the image-side surface S4 of the second lens 210 can also be any of a convex surface, a concave surface, or a plane. This application embodiment does not limit this, as long as the image-side surface S4 of the second lens 210 and the object-side surface S4 of the third lens 310 are in contact, and the second lens 210 has negative optical power.

[0113] Since the image-side surface of the second lens 210 is in contact with the object-side surface of the third lens 310, the object-side surface S4 of the third lens 310 is convex, and the image-side surface S5 of the third lens 310 is also convex. This improves the imaging effect and image quality of the projection lens 100.

[0114] In other words, the third lens 310 is a biconvex lens with positive optical power.

[0115] It is understood that the object-side surface S4 of the third lens 310 can be any of a convex surface, a concave surface, or a plane, and the image-side surface S5 of the third lens 310 can also be any of a convex surface, a concave surface, or a plane. This application embodiment does not limit this, as long as the object-side surface S4 of the third lens 310 and the image-side surface S4 of the second lens 210 are in contact, and the third lens 310 has positive optical power.

[0116] Among them, such as Figure 3 As shown, the projection lens 100 also includes an aperture stop 410. In this case, the object-side surface S3 of the second lens 210 serves as the aperture stop 410. The aperture stop 410 can be used to limit the aperture of the projection lens, thereby limiting the amount of light entering the lens to change the image brightness.

[0117] In the projection lens 100 provided in this embodiment, lenses with positive optical power (e.g., the first lens 110 and the third lens 310) are made of materials with low dispersion coefficients, while lenses with negative optical power (e.g., the second lens 210) are made of materials with high dispersion coefficients. In other words, lenses with low refractive index use materials with high Abbe numbers, and lenses with high refractive index use materials with low Abbe numbers. This allows the various lenses of the projection lens 100 to complement each other in terms of dispersion capability, achieving a balance and thus eliminating chromatic aberration, further improving image quality.

[0118] Among them, the Abbe number vd2 of the second lens 210 and the Abbe number vd3 of the third lens 310 satisfy: vd3 / vd2≥2.

[0119] The total focal length of the projection lens 100 is the effective focal length EFL of the projection lens 100 formed by the first lens 110, the second lens 210 and the third lens 310. The effective focal length EFL of the projection lens 100 is related to the focal length of each lens.

[0120] In this embodiment of the application, the focal length f1 of the first lens 110 and the effective focal length EFL of the projection lens 100 satisfy: |f1 / EFL|≥10.

[0121] The focal length f2 of the second lens 210 and the focal length f3 of the third lens 310 satisfy: 1.7≤|f2 / f3|≤3.7.

[0122] The combined focal length f23 of the cemented lens formed by the second lens 210 and the third lens 310 satisfies the following condition with respect to the effective focal length EFL of the projection lens 100: 0.8 ≤ |f23 / EFL| ≤ 1.5.

[0123] This will help improve the imaging quality of the projection lens 100.

[0124] In some embodiments, the object-side surface S1 and the image-side surface S2 of the first lens 110 are both aspherical.

[0125] In some embodiments, the object-side surface and image-side surface of the second lens 210 and the third lens 310 are both spherical. Spherical lenses are less expensive, which can reduce the cost of the projection lens 100.

[0126] In this embodiment, the first lens 110 is a plastic lens, and the second lens 210 and the third lens 310 are both glass lenses.

[0127] The second lens 210 and the third lens 310 are located on the side of the first lens 110 closer to the laser source 200, and are easily affected by temperature. Therefore, setting the second lens 210 and the third lens 310 as glass lenses can improve the reliability of the projection lens 100.

[0128] The projection lens 100 provided in this application uses a combination of glass and plastic lenses, which can effectively reduce costs while ensuring reliability.

[0129] Furthermore, using a combination of glass and plastic lenses can correct the temperature drift of the projection lens 100, thereby reducing its temperature drift under any operating temperature and achieving good optical imaging results. This is because the temperature coefficient of refractive index of the plastic lens satisfies: DN / DT < 0, while the temperature coefficient of refractive index of the glass lens satisfies: DN / DT > 0, where DN is the change in refractive index per unit time, and DT is the change in temperature per unit time. When the temperature increases, the refractive index of the glass lens increases accordingly, while the refractive index of the plastic lens decreases accordingly.

[0130] In this way, by using the matching compensation of the refractive index temperature coefficients DN / DT of the lenses, a heat difference mitigation design with mutual compensation is achieved, improving the reliability of the projection lens 100 and meeting the high and low temperature reliability requirements of the projection system 10. After the projection lens 100 is focused at room temperature, it can achieve clear imaging without refocusing in an ambient temperature range of -40℃ to 105℃, thus balancing the high reliability and low cost of the projection lens 100.

[0131] In this embodiment, the total optical length (TTL) of the projection lens 100 and the effective focal length (EFL) of the projection lens 100 satisfy: 1.5 ≤ TTL / EFL ≤ 2.5, thereby achieving a small volume of the projection lens 100.

[0132] In this embodiment, the back focal length BFL of the projection lens 100 and the effective focal length EFL of the projection lens 100 satisfy: 0.5≤BFL / EFL≤1.5, thereby achieving a long back focal length for the projection lens 100.

[0133] The projection lens 100 provided in this application embodiment includes: a first lens 110 with optical power, a second lens 210 with negative optical power, and a third lens 310 with positive optical power, arranged sequentially from the object side to the image side along the optical axis. The image side of the second lens 210 and the object side of the third lens 310 are attached. The projection lens 100 provided in this application embodiment arranges the first lens 110 with optical power, the second lens 210 with negative optical power, and the third lens 310 with positive optical power in a specific order from the object side to the image side along the optical axis. Through the mutual cooperation between the lenses, the projection lens 100 satisfies the following: the focal length f1 of the first lens 110, the focal length f2 of the second lens 210, the focal length f3 of the third lens 310, the combined focal length f23 of the second lens 210 and the third lens 310, and the effective focal length EFL of the projection lens 100 satisfy:

[0134] At least one of the following conditions—|f1 / EFL|≥10, 1.7≤|f2 / f3|≤3.7, or 0.8≤|f23 / EFL|≤1.5—is beneficial for controlling the light deflection angle, balancing aberrations, improving the imaging quality of the projection lens 100, and achieving a large aperture design. Therefore, the projection lens provided in this embodiment can achieve a projection lens with characteristics such as large aperture, low cost, small size, and high resolution. Furthermore, the projection image of the projection lens 100 has uniform brightness, achieving clear projection at the megapixel level and improving the energy transmission efficiency of the projection system 10.

[0135] Meanwhile, the projection lens 100 provided in this application embodiment meets the design requirements for reducing thermal difference in the temperature range of -40℃ to 105℃, and meets the reliability requirements at high and low temperatures.

[0136] In addition, the projection lens 100 provided in this application embodiment can effectively correct field curvature and distortion, achieving low distortion and no image loss. Moreover, when the projection lens is moved, it can focus clearly with no significant change in field curvature.

[0137] The projection lens 100 provided in this embodiment consists of only three lenses, and the ratio of the total optical length (TTL) to the effective focal length (EFL) of the projection lens 100 is less than 2.5, thus meeting the requirements for small size and simple structure of the projection lens 100. The ratio of the back focal length (BFL) to the effective focal length (EFL) of the projection lens 100 provided in this embodiment is greater than 0.5, satisfying the usage scenarios of a long back focal length projection lens 100.

[0138] The following will describe in more detail, with reference to the accompanying drawings, some specific but not limiting examples of the embodiments provided in this application.

[0139] Example 1

[0140] like Figure 3 As shown, the projection lens 100 provided in Embodiment 1 of this application includes a first lens 110, a second lens 210 and a third lens 310 arranged sequentially from the object side to the image side along the optical axis.

[0141] In this configuration, the image-side surface of the second lens 210 and the object-side surface of the third lens 310 are bonded together. For example, the second lens 210 and the third lens 310 form a cemented lens. This suppresses optical chromatic aberration in the projection lens 100, thereby enabling the projection lens 100 to achieve better imaging results.

[0142] The first lens 110 has a concave object-side surface S1 and a convex image-side surface S2, making it a meniscus lens with positive optical power. The second lens 210 has a convex object-side surface S3 and a concave image-side surface S4, making it a meniscus lens with negative optical power. The third lens 310 has a convex object-side surface S4 and a convex image-side surface S5, making it a biconvex lens with positive optical power.

[0143] like Figure 3 As shown, the projection lens 100 provided in Embodiment 1 also includes an aperture stop 510. The aperture stop 510 is disposed on the object side surface S3 of the second lens 210.

[0144] The focal length f1 of the first lens 110 and the effective focal length EFL of the projection lens 100 satisfy: |f1 / EFL|≥10.

[0145] The focal length f2 of the second lens 210 and the focal length f3 of the third lens 310 satisfy: 1.7≤|f2 / f3|≤3.7.

[0146] The combined focal length f23 of the cemented lens formed by the second lens 210 and the third lens 310 satisfies the following condition with respect to the effective focal length EFL of the projection lens 100: 0.8 ≤ |f23 / EFL| ≤ 1.5.

[0147] The first lens 110 is a plastic lens, while the second lens 210 and the third lens 310 are glass lenses. By combining glass and plastic lenses and utilizing the matching of their refractive index temperature coefficients DN / DT, a mutually compensating thermal difference design is achieved. This corrects the temperature drift of the projection lens 100, thereby reducing its temperature drift under any operating temperature, achieving good optical imaging results, improving the reliability of the projection lens 100, and meeting the high and low temperature reliability requirements of the projection system 10. This approach balances high reliability and low cost for the projection lens 100.

[0148] The Abbe number vd1 of the first lens 110 satisfies: vd1≥52. The Abbe number vd2 of the second lens 210 and the Abbe number vd3 of the third lens 310 satisfy: vd3 / vd2≥2.

[0149] The projection lens 100 uses a combination of positive power lenses with low dispersion and negative power lenses with high dispersion to achieve the purpose of eliminating chromatic aberration.

[0150] Table 1-1 below shows the optical parameters of the projection lens 100 provided in Embodiment 1 of this application.

[0151] Where F# is the aperture value of the projection lens 100; EFL is the effective focal length of the projection lens 100; FOV is the field of view of the projection lens 100; TTL is the total optical length of the projection lens 100; TTL / EFL is the ratio of the total optical length TTL of the projection lens 100 to the effective focal length EFL of the projection lens 100; BFL / EFL is the ratio of the back focal length BFL of the projection lens 100 to the effective focal length EFL of the projection lens 100.

[0152] Table 1-1

[0153] EFL 44.82mm FOV 8.9° TTL 89.80mm TTL / EFL 2.00 BFL / EFL 1.07

[0154] Tables 1-2 below show the optical parameters of each lens in the projection lens 100 provided in Embodiment 1 of this application.

[0155] Where R is the radius of curvature; Th is the center thickness of the lens; Nd is the refractive index of the lens; and vd is the Abbe number of the lens.

[0156] Table 1-2

[0157]

[0158] Tables 1-3 below show the aspherical coefficients of the first lens 110 in the projection lens 100 provided in Embodiment 1 of this application.

[0159] Where K is the quadratic surface constant, and A2, A4, A6 and A8 are the second-order, fourth-order, sixth-order and eighth-order aspherical coefficients, respectively.

[0160] Table 1-3

[0161] S1 -1.00E+00 0 -1.68E-05 -3.42E-08 3.40E-11 S2 -1.09E+00 0 -7.77E-06 -8.18E-09 5.90E-12

[0162] To facilitate understanding of the projection lens 100 provided in Embodiment 1 of this application, a simulation was performed, and the simulation effect is described below.

[0163] Figure 4A The example shown is the use of Figure 3 The projection lens 100 structure shown above, and using the data shown in Tables 1-1, 1-2 and 1-3 above, is the modulation transfer function (MTF) curve of the projection lens 100 at room temperature (20°C).

[0164] Figure 4B The example shown is the use of Figure 3 The projection lens 100 structure shown above, and using the data shown in Tables 1-1, 1-2 and 1-3 above, is a modulation transfer function curve of the projection lens 100 at low temperature (-40°C).

[0165] Figure 4C The example shown is the use of Figure 3 The projection lens 100 structure shown above, and using the data shown in Tables 1-1, 1-2 and 1-3 above, is a modulation transfer function curve of the projection lens 100 at high temperature (105°C).

[0166] Figure 4A , Figure 4B as well as Figure 4C The horizontal axis represents spatial frequency, with units of line pairs per millimeter (LP / mm), and the vertical axis represents the modulation transfer function.

[0167] The lines in the figure represent the relationship between the modulation transfer function and spatial frequency at different field of view angles. Here, T represents the meridional direction, and S represents the arc direction.

[0168] from Figure 4A The MTF curve of the projection lens 100 shown at room temperature shows that at a spatial frequency of 16.5 LP / mm, the MTF corresponding to the center field of view (0.0000mm) is above 0.7, and the MTF corresponding to the 0.7 times image height IH field of view (4.8680mm) is above 0.4, which meets the requirements of the human eye's limit angular resolution.

[0169] from Figure 4B and Figure 4C The MTF curves of the projection lens 100 shown at low and high temperatures indicate that at a spatial frequency of 16.5 LP / mm, the MTF corresponding to the center field of view is above 0.7, and the MTF corresponding to the 0.7 times image height IH field of view is above 0.3. It meets the human eye's limit angular resolution requirements within a temperature range from -40℃ to 105℃. The projection lens 100 of Embodiment 1 of this application achieves the thermal difference reduction effect.

[0170] from Figure 4A , Figure 4B as well as Figure 4C As can be seen, the projection lens 100 of Embodiment 1 of this application exhibits minimal differences in imaging distortion at both low and high temperatures. At different temperatures, the modulation transfer function of the projection lens 100 remains essentially the same, resulting in good temperature drift correction and meeting the requirement for clear imaging over a wide temperature range. In other words, the projection lens 100 of Embodiment 1 of this application can produce clear images under wide temperature conditions; that is, the temperature drift of the projection lens 100 is small over a large temperature variation range. Therefore, the projection lens 100 of Embodiment 1 of this application can achieve good imaging results at different temperatures.

[0171] Figure 4D The example shown is the use of Figure 3 The field curvature curve of the projection lens 100 is shown in Tables 1-1, 1-2 and 1-3 above, when the projection lens 100 structure is shown.

[0172] Figure 4D The x-axis represents the field curvature in mm, and the y-axis represents the normalized image height. Here, T represents the meridional direction, and S represents the arc-induced direction.

[0173] Depend on Figure 4D As can be seen, the projection lens 100 provided in Embodiment 1 of this application has a relatively small field curvature from light with a wavelength of 460nm to light with a wavelength of 617nm.

[0174] Figure 4E The example shown is the use of Figure 3 The distortion curve of the projection lens 100 is shown in Tables 1-1, 1-2 and 1-3 above, when the projection lens 100 structure is shown.

[0175] Figure 4E The horizontal axis represents the magnitude of distortion, expressed as a percentage, while the vertical axis represents the normalized image height, which has no unit.

[0176] Depend on Figure 4E As can be seen, the distortion is less than 1%. The distortion of the projection lens 100 provided in Embodiment 1 of this application is well corrected, and the imaging distortion is small, meeting the requirements for low distortion.

[0177] Figure 4F The example shown is the use of Figure 3 The relative illumination curves of the projection lens 100 are shown in Tables 1-1, 1-2 and 1-3 above, when using the structure of the projection lens 100.

[0178] Relative illumination (RI) is the ratio of the edge illumination to the center illumination of an imaging surface. Figure 4F The origin (0, 0) is the center of the imaging plane. The x-axis represents the distance from the edge to the center, and the y-axis represents the relative illumination.

[0179] Figure 4F The relative illumination curve of the projection lens 100 shown can be seen as follows: Figure 4F The origin (0, 0) is the center of the imaging surface, with a brightness of 100%. As the image moves towards the edge of the imaging surface, the brightness at the edge gradually decreases until it reaches approximately 90% at a distance of 6.954 mm from the center. Therefore, the projection image of the projection lens 100 provided in Embodiment 1 of this application has uniform brightness.

[0180] Figure 4G The example shown is the use of Figure 3 The diagram shows the defocus modulation transfer function curve of the projection lens 100 structure and the data shown in Tables 1-1, 1-2 and 1-3 above.

[0181] Figure 4G The horizontal axis represents the focus offset in millimeters (mm), and the vertical axis represents the modulation transfer function.

[0182] Depend on Figure 4G It can be seen that the peak values ​​of the MTF curves of the projection lens 100 provided in Embodiment 1 of this application are relatively concentrated and the peak widths are relatively wide from the center field of view to the field of view of 1 times the image height (IH). When the focus offset is between -0.2 and 0.2, the modulation transfer function is still at a relatively high value.

[0183] The projection lens 100 provided in Embodiment 1 of this application uses three lenses working together to achieve an aperture of F1.32. Field curvature and distortion can be effectively corrected, resulting in better optical performance while satisfying the requirements of large aperture, high reliability, and low cost.

[0184] Example 2

[0185] like Figure 3 As shown, the projection lens 100 provided in Embodiment 2 of this application includes a first lens 110, a second lens 210 and a third lens 310 arranged sequentially from the object side to the image side along the optical axis.

[0186] In this configuration, the image-side surface of the second lens 210 and the object-side surface of the third lens 310 are bonded together. For example, the second lens 210 and the third lens 310 form a cemented lens. This suppresses optical chromatic aberration in the projection lens 100, thereby enabling the projection lens 100 to achieve better imaging results.

[0187] The first lens 110 has a concave object-side surface S1 and a convex image-side surface S2, making it a meniscus lens with positive optical power. The second lens 210 has a convex object-side surface S3 and a concave image-side surface S4, making it a meniscus lens with negative optical power. The third lens 310 has a convex object-side surface S4 and a convex image-side surface S5, making it a biconvex lens with positive optical power.

[0188] like Figure 3 As shown, the projection lens 100 provided in Embodiment 2 also includes an aperture stop 510. The aperture stop 510 is disposed on the object side surface S3 of the second lens 210.

[0189] The focal length f1 of the first lens 110 and the effective focal length EFL of the projection lens 100 satisfy: |f1 / EFL|≥10.

[0190] The focal length f2 of the second lens 210 and the focal length f3 of the third lens 310 satisfy: 1.7≤|f2 / f3|≤3.7.

[0191] The combined focal length f23 of the cemented lens formed by the second lens 210 and the third lens 310 satisfies the following condition with respect to the effective focal length EFL of the projection lens 100: 0.8 ≤ |f23 / EFL| ≤ 1.5.

[0192] The first lens 110 is a plastic lens, while the second lens 210 and the third lens 310 are glass lenses. By combining glass and plastic lenses and utilizing the matching of their refractive index temperature coefficients DN / DT, a mutually compensating thermal difference design is achieved. This corrects the temperature drift of the projection lens 100, thereby reducing its temperature drift under any operating temperature, achieving good optical imaging results, improving the reliability of the projection lens 100, and meeting the high and low temperature reliability requirements of the projection system 10. This approach balances high reliability and low cost for the projection lens 100.

[0193] The Abbe number vd1 of the first lens 110 satisfies: vd1≥52. The Abbe number vd2 of the second lens 210 and the Abbe number vd3 of the third lens 310 satisfy: vd3 / vd2≥2.

[0194] The projection lens 100 uses a combination of positive power lenses with low dispersion and negative power lenses with high dispersion to achieve the purpose of eliminating chromatic aberration.

[0195] Table 2-1 below shows the optical parameters of the projection lens 100 provided in Embodiment 2 of this application.

[0196] The physical meaning of each optical parameter is the same as that in Table 1-1 above, and will not be repeated here.

[0197] Table 2-1

[0198]

[0199]

[0200] Table 2-2 below shows the optical parameters of each lens in the projection lens 100 provided in Embodiment 2 of this application.

[0201] The physical meaning of each optical parameter is the same as that in Table 1-2 above, and will not be repeated here.

[0202] Table 2-2

[0203]

[0204] Tables 2-3 below show the aspherical coefficients of the first lens 110 in the projection lens 100 provided in Embodiment 2 of this application.

[0205] The physical meaning of each optical parameter is the same as that in Table 1-3 above, and will not be repeated here.

[0206] Table 2-3

[0207] S1 -9.80E-01 0 -8.65E-05 -5.80E-07 1.89E-09 S2 -1.13E+00 0 -4.44E-06 -1.51E-07 3.68E-10

[0208] To facilitate understanding of the projection lens 100 provided in Embodiment 2 of this application, a simulation was performed, and the simulation effect is described below.

[0209] Figure 5A The example shown is the use of Figure 3 The projection lens 100 structure shown above, and using the data shown in Tables 2-1, 2-2 and 2-3 above, is the modulation transfer function curve of the projection lens 100 at room temperature (20℃).

[0210] Figure 5B The example shown is the use of Figure 3 The projection lens 100 structure shown above, and using the data shown in Tables 2-1, 2-2 and 2-3 above, is a modulation transfer function curve of the projection lens 100 at low temperature (-40℃).

[0211] Figure 5C The example shown is the use of Figure 3 The projection lens 100 structure shown above, and using the data shown in Tables 2-1, 2-2 and 2-3 above, is a modulation transfer function curve of the projection lens 100 at high temperature (105°C).

[0212] Figure 5A , Figure 5B as well as Figure 5C The horizontal axis represents spatial frequency, with units of line pairs per millimeter (LP / mm), and the vertical axis represents the modulation transfer function.

[0213] The lines in the figure represent the relationship between the modulation transfer function and spatial frequency at different field of view angles. Here, T represents the meridional direction, and S represents the arc direction.

[0214] from Figure 5A The MTF curve of the projection lens 100 shown at room temperature shows that at a spatial frequency of 16.5 LP / mm, the MTF corresponding to the center field of view (0.0000mm) is above 0.8, and the MTF corresponding to the 1x image height IH field of view (3.7700mm) is above 0.6, which meets the requirements of the human eye's limit angular resolution.

[0215] from Figure 5B and Figure 5CThe MTF curves of the projection lens 100 shown at low and high temperatures indicate that at a spatial frequency of 16.5 LP / mm, the MTF corresponding to the center field of view is above 0.8, and the MTF corresponding to the IH field of view at 1x image height is above 0.5. It meets the human eye's limit angular resolution requirements within a temperature range from -40℃ to 105℃. The projection lens 100 of Embodiment 2 of this application achieves the thermal difference reduction effect.

[0216] from Figure 5A , Figure 5B as well as Figure 5C As can be seen, the projection lens 100 of Embodiment 2 of this application exhibits minimal differences in imaging distortion at both low and high temperatures. At different temperatures, the modulation transfer function of the projection lens 100 remains essentially the same, resulting in good temperature drift correction and meeting the requirement for clear imaging over a wide temperature range. In other words, the projection lens 100 of Embodiment 2 of this application can produce clear images under wide temperature conditions; that is, the temperature drift of the projection lens 100 is small over a large temperature variation range. Therefore, the projection lens 100 of Embodiment 2 of this application can achieve good imaging results at different temperatures.

[0217] Figure 5D The example shown is the use of Figure 3 The field curvature curve of the projection lens 100 is shown in Tables 2-1, 2-2 and 2-3 above, when the projection lens 100 structure is shown.

[0218] Figure 5D The x-axis represents the field curvature in mm, and the y-axis represents the normalized image height. Here, T represents the meridional direction, and S represents the arc-induced direction.

[0219] Depend on Figure 5D As can be seen, the projection lens 100 provided in Embodiment 2 of this application has a relatively small field curvature from light with a wavelength of 460nm to light with a wavelength of 617nm.

[0220] Figure 5E The example shown is the use of Figure 3 The distortion curve of the projection lens 100 is shown in Tables 2-1, 2-2 and 2-3 above, when the projection lens 100 structure is shown.

[0221] Figure 5E The horizontal axis represents the magnitude of distortion, expressed as a percentage, while the vertical axis represents the normalized image height, which has no unit.

[0222] Depend on Figure 5E As can be seen, the distortion is less than 1%. The distortion of the projection lens 100 provided in Embodiment 2 of this application is well corrected, and the imaging distortion is small, meeting the requirement of low distortion.

[0223] Figure 5FThe example shown is the use of Figure 3 The relative illumination curve of the projection lens 100 is shown in Tables 2-1, 2-2 and 2-3 above, when the projection lens 100 structure is shown.

[0224] Relative illuminance refers to the ratio of the illuminance at the edge of the imaging surface to the illuminance at the center. Figure 5F The origin (0, 0) is the center of the imaging plane. The x-axis represents the distance from the edge to the center, and the y-axis represents the relative illumination.

[0225] Figure 5F The relative illumination curve of the projection lens 100 shown can be seen as follows: Figure 5F The origin (0, 0) is the center of the imaging surface, with a brightness of 100%. As the image moves towards the edge of the imaging surface, the brightness at the edge gradually decreases until it reaches approximately 90% at a distance of 3.77 mm from the center. Therefore, the projection image of the projection lens 100 provided in Embodiment 2 of this application has uniform brightness.

[0226] Figure 5G The example shown is the use of Figure 3 The diagram shows the defocus modulation transfer function curve of the projection lens 100 structure and the data shown in Tables 2-1, 2-2 and 2-3 above.

[0227] Figure 5G The horizontal axis represents the focus offset in millimeters (mm), and the vertical axis represents the modulation transfer function.

[0228] Depend on Figure 5G It can be seen that the peak values ​​of the MTF curves of the projection lens 100 provided in Embodiment 2 of this application are relatively concentrated and the peak widths are relatively wide from the center field of view to the field of view of 1 times the image height (IH). When the focus offset is between -0.2 and 0.2, the modulation transfer function is still at a relatively high value.

[0229] The projection lens 100 provided in Embodiment 2 of this application employs three lenses working together, making it suitable for smaller target surfaces. While improving resolution, it further reduces the size of the projection lens 100. The aperture can reach F1.31, and field curvature and distortion can be effectively corrected, resulting in superior optical performance while simultaneously satisfying the requirements of a large aperture, high reliability, and low cost.

[0230] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A projection lens, characterized in that, include: Along the optical axis, a first lens, a second lens, and a third lens are arranged sequentially from the object side to the image side; the projection lens contains three lenses with optical power. The first lens has positive optical power; The second lens has negative optical power; The third lens has positive optical power; the image side of the second lens and the object side of the third lens are attached together; Wherein, the focal length f1 of the first lens, the focal length f2 of the second lens, the focal length f3 of the third lens, the combined focal length f23 of the second lens and the third lens, and the effective focal length EFL of the projection lens satisfy at least one of the following: |f1 / EFL|≥10, 1.7≤|f2 / f3|≤3.7, or 0.8≤|f23 / EFL|≤1.5; the total optical length TTL of the projection lens and the effective focal length EFL of the projection lens satisfy: 1.5≤TTL / EFL≤2.

5.

2. The projection lens according to claim 1, characterized in that, The object-side surface of the first lens is concave; the image-side surface of the first lens is convex.

3. The projection lens according to claim 1 or 2, characterized in that, The object-side surface of the second lens is convex; the image-side surface of the second lens is concave.

4. The projection lens according to claim 1 or 2, characterized in that, The image-side surface of the third lens is convex.

5. The projection lens according to claim 1 or 2, characterized in that, The first lens is a plastic lens; the second lens and the third lens are glass lenses.

6. The projection lens according to claim 1 or 2, characterized in that, The second lens and the third lens together form a cemented lens.

7. The projection lens according to claim 1 or 2, characterized in that, Both the object-side and image-side surfaces of the first lens are aspherical.

8. The projection lens according to claim 1 or 2, characterized in that, The object-side surface and the image-side surface of the second lens and the third lens are both spherical.

9. The projection lens according to claim 1 or 2, characterized in that, The Abbe number vd1 of the first lens satisfies: vd1≥52.

10. The projection lens according to claim 1 or 2, characterized in that, The Abbe number vd2 of the second lens and the Abbe number vd3 of the third lens satisfy: vd3 / vd2≥2.

11. The projection lens according to claim 1 or 2, characterized in that, The back focal length BFL of the projection lens and the effective focal length EFL of the projection lens satisfy the following condition: 0.5≤BFL / EFL≤1.

5.

12. A projection system, characterized in that, include: A light source, a light valve modulation component, and a projection lens as described in any one of claims 1-11; The light valve modulation component is located on the light-emitting side of the light source and is used to modulate and reflect the incident light. The projection lens is located on the reflected light path of the light valve modulation component and is used to image the emitted light of the light valve modulation component.

13. A car, characterized in that, include: The projection system and processing unit as described in claim 12; the processing unit is used to control the projection system.

Images