Projection lens and head-up display system

Abstract

The utility model discloses a projection lens and a head-up display system, and relates to the technical field of vehicle-mounted head-up display systems, and the projection lens sequentially comprises a display chip, a lens assembly and a projection surface along the light transmission direction. The lens assembly is composed of a first lens, a second lens, a third lens, a fourth lens and a fifth lens which are sequentially arranged along the same optical axis in the direction from the projection plane to the display chip. The first lens has negative focal power. The projection lens satisfies the following conditions: 0.7 lt; d1 / EFLlt; 1.05, EFL represents the focal length of the projection lens, and D1 represents the aperture of the first lens; a direction perpendicular to the optical axis is defined as a first direction, and the projection surface is obliquely arranged relative to the first direction; according to the technical scheme of the utility model, the adaptability of the projection lens and the diffusion sheet can be improved, and the production and manufacturing cost of the head-up display system can be reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of vehicle head-up display systems, and particularly relates to a projection lens and a head-up display system. Background Art

[0002] In the related art, a head-up display system can adopt a DLP (Digital Light Processor) scheme for imaging. In the DLP scheme, a diffuser is usually disposed on the projection surface of the projection lens. Since there is a phenomenon of sunlight backflow in the application of the head-up display system, that is, sunlight rays will enter against the projection optical path in the DLP scheme and enter the driver's eyes after being reflected by the diffuser, which will cause the problems of increased temperature of the diffuser and stray light in the head-up display system. At present, for the problems caused by the sunlight backflow phenomenon, the off-axis design of the projection lens and the way of increasing the deflection angle of the diffuser are usually adopted to solve the problems. However, this way will increase the design and manufacturing difficulty and cost of the diffuser, thereby increasing the production and manufacturing cost of the head-up display system. Summary of the Utility Model

[0003] The main object of the utility model is to propose a projection lens and a projection device, aiming to improve the adaptability between the projection lens and the diffuser and reduce the production and manufacturing cost of the head-up display system.

[0004] To achieve the above object, the projection lens proposed by the utility model sequentially includes a display chip, a lens assembly and a projection surface along the light transmission direction. The lens assembly is composed of a first lens, a second lens, a third lens, a fourth lens and a fifth lens which are sequentially arranged along the same optical axis from the projection surface to the display chip. The first lens has a negative focal power.

[0005] The projection lens satisfies: 0.7 < D1 / EFL < 1.05, where EFL represents the focal length of the projection lens, and D1 represents the aperture of the first lens.

[0006] Define the direction perpendicular to the optical axis as the first direction. The display chip is inclined relative to the first direction, and the projection surface is inclined relative to the first direction.

[0007] In an embodiment, the inclination angle range of the display chip relative to the first direction is 0 to 2.1°.

[0008] The inclination angle range of the projection surface relative to the first direction is 0 to 20°.

[0009] In an embodiment, the first lens has a first surface convex towards the projection surface and a second surface concave towards the display chip.

[0010] The second lens has a first surface convex towards the projection surface and a second surface convex towards the display chip;

[0011] The third lens has a first surface concave towards the projection surface and a second surface concave towards the display chip;

[0012] The fourth lens has a first surface convex towards the projection surface and a second surface convex towards the display chip;

[0013] The fifth lens has a first surface convex towards the projection surface and a second surface convex towards the display chip.

[0014] In one embodiment, the first lens and the fifth lens are plastic aspherical lenses, and the second lens, the third lens, and the fourth lens are glass spherical lenses.

[0015] In one embodiment, the refractive index temperature coefficient of the glass spherical lens material is dn / dt, satisfying the relationship: dn / dt > 3.5×10-6 / °C.

[0016] In one embodiment, the refractive index temperature coefficient of the second lens is dn / dt2, satisfying the relationship: dn / dt2 > 3.5×10-6 / °C;

[0017] The refractive index temperature coefficient of the third lens is dn / dt3, satisfying the relationship: dn / dt3 < 1.0×10-6 / °C

[0018] The refractive index temperature coefficient of the fourth lens is dn / dt4, satisfying the relationship: dn / dt4 > 3.0×10-6 / °C.

[0019] In one embodiment, the second lens and the third lens are adhesively connected, and a diaphragm is provided between the third lens and the fourth lens;

[0020] Or, the third lens and the fourth lens are adhesively connected, and a diaphragm is provided between the second lens and the third lens.

[0021] In one embodiment, the refractive index of the first lens is Nd1, and the Abbe number of the first lens is Vd1, satisfying the relationship: Nd1 < 1.65, Vd1 > 45;

[0022] The refractive index of the second lens is Nd2, and the Abbe number of the second lens is Vd2, satisfying the relationship: Nd2 > 1.75, Vd2 < 45;

[0023] The refractive index of the third lens is Nd3, and the Abbe number of the third lens is Vd3, satisfying the relationship: Nd3 > 1.75, Vd3 < 45;

[0024] The refractive index of the fourth lens is Nd4, and the Abbe number of the fourth lens is Vd4, satisfying the relational expression: Nd4 > 1.7, Vd4 > 45;

[0025] The refractive index of the fifth lens is Nd5, and the Abbe number of the fifth lens is Vd5, satisfying the relational expression: Nd5 < 1.65, Vd5 > 45.

[0026] In one embodiment, the projection lens satisfies the following relational expressions:

[0027] 3.5 < TTL / EFL < 5;

[0028] 0.19 < BFL / EFL < 0.55;

[0029] Wherein, TTL represents the overall optical length of the projection lens, EFL represents the focal length of the projection lens, and BFL represents the back focal length of the projection lens.

[0030] The present utility model further provides a head-up display system, including the projection lens described in any one of the foregoing items. The projection lens sequentially includes a display chip, a lens assembly, and a projection surface along the light transmission direction. The lens assembly is composed of a first lens, a second lens, a third lens, a fourth lens, and a fifth lens sequentially arranged along the same optical axis from the projection surface to the display chip direction. The first lens has a negative optical power;

[0031] The projection lens satisfies: 0.7 < D1 / EFL < 1.05, wherein, EFL represents the focal length of the projection lens, and D1 represents the aperture of the first lens;

[0032] Define the direction perpendicular to the optical axis as the first direction. The display chip is inclined with respect to the first direction, and the projection surface is inclined with respect to the first direction.

[0033] The projection optical system of the technical solution of the present utility model sequentially includes a display chip, a lens assembly, and a projection surface along the light transmission direction. Among them, several lenses of the lens assembly are sequentially arranged along the same optical axis from the projection surface to the display chip. Define the direction perpendicular to the optical axis as the first direction, and set the projection surface to be inclined with respect to the first direction, which can achieve an inclination of the projection surface with respect to the image surface by a certain angle. Therefore, it is beneficial to reduce the required deflection angle of the diffuser provided on the projection surface when solving the problem of sunlight backflow. As a result, the adaptability of the projection lens and the diffuser can be improved, which is beneficial to reducing the cost of the projection lens with the diffuser, and thus can reduce the production and manufacturing cost of the head-up display system. The present invention also defines that the first lens 21 has a negative optical power, and the ratio range of the aperture D1 of the first lens to the focal length EFL is between 0.7 and 1.05, thereby realizing the design optimization of the projection lens to ensure the imaging quality and head of the projection lens. Description of the Drawings

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following-described drawings are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0035] Figure 1 Schematic structural diagram of an embodiment of the projection lens provided by the present utility model;

[0036] Figure 2 MTF diagram of the projection lens provided in Embodiment 1 of the present utility model at an ambient temperature of 25°C;

[0037] Figure 3 MTF diagram of the projection lens provided in Embodiment 1 of the present utility model at an ambient temperature of -40°C;

[0038] Figure 4 MTF diagram of the projection lens provided in Embodiment 1 of the present utility model at an ambient temperature of 85°C;

[0039] Figure 5 Chromatic aberration diagram of the projection lens provided in Embodiment 1 of the present utility model;

[0040] Figure 6 Field curvature and distortion diagram of the projection lens provided in Embodiment 1 of the present utility model;

[0041] Figure 7 Relative illuminance diagram of the projection lens provided in Embodiment 1 of the present utility model;

[0042] Figure 8MTF diagram of the projection lens provided in Embodiment 2 of the present utility model at an ambient temperature of 25°C;

[0043] Figure 9 MTF diagram of the projection lens provided in Embodiment 2 of the present utility model at an ambient temperature of -40°C;

[0044] Figure 10 MTF diagram of the projection lens provided in Embodiment 2 of the present utility model at an ambient temperature of 85°C;

[0045] Figure 11 Chromatic aberration diagram of the projection lens provided in Embodiment 2 of the present utility model;

[0046] Figure 12 Field curvature and distortion diagram of the projection lens provided in Embodiment 2 of the present utility model;

[0047] Figure 13 Relative illumination diagram of the projection lens provided in Embodiment 2 of the present utility model;

[0048] Figure 14 MTF diagram of the projection lens provided in Embodiment 3 of the present utility model at an ambient temperature of 25°C;

[0049] Figure 15 MTF diagram of the projection lens provided in Embodiment 3 of the present utility model at an ambient temperature of -40°C;

[0050] Figure 16 MTF diagram of the projection lens provided in Embodiment 3 of the present utility model at an ambient temperature of 85°C;

[0051] Figure 17 Chromatic aberration diagram of the projection lens provided in Embodiment 3 of the present utility model;

[0052] Figure 18 Field curvature and distortion diagram of the projection lens provided in Embodiment 3 of the present utility model;

[0053] Figure 19 Relative illumination diagram of the projection lens provided in Embodiment 3 of the present utility model.

[0054] Explanation of the reference numerals in the drawings:

[0055] 100, projection lens; 10, display chip; 20, lens assembly; 21, first lens; 22, second lens; 23, third lens; 24, fourth lens; 25, fifth lens; 30, projection surface; 40, aperture stop; 50, equivalent prism; 60, protective glass.

[0056] The realization, functional features and advantages of the purpose of the present utility model will be further described with reference to the embodiments and the accompanying drawings. Detailed implementation manners

[0057] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0058] It should be noted that if there are directional indications (such as up, down, left, right, front, back...) involved in the embodiments of the present invention, the directional indications are only used to explain the relative position relationship and movement conditions between components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0059] In addition, if there are descriptions such as "first", "second", etc. involved in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, if "and / or" or "and / or" appears throughout the text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or a solution where A and B are satisfied simultaneously. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0060] In the related art, the head-up display system can adopt a DLP (Digital Light Processor) solution for imaging. In the DLP solution, the diffuser is usually disposed on the projection surface of the projection lens. Since there is a phenomenon of sunlight backflow in the application of the head-up display system, that is, sunlight rays will enter against the projection optical path in the DLP solution and enter the driver's eyes after being reflected by the diffuser, which will cause problems such as an increase in the temperature of the diffuser and the appearance of stray light in the head-up display system. Currently, for the problems caused by the sunlight backflow phenomenon, the off-axis design of the projection lens and the way of increasing the deflection angle of the diffuser are often used to solve the problem. However, this way will increase the design and manufacturing difficulty and cost of the diffuser, thereby increasing the production and manufacturing cost of the head-up display system.

[0061] The present invention provides a projection lens 100, which can be applied to vehicle-mounted projection devices such as head-up display systems and other vehicle-mounted projection fields.

[0062] Please refer to Figure 1 In an embodiment of the present utility model, the projection lens 100 sequentially includes a display chip 10, a lens assembly 20, and a projection surface along the light transmission direction. The lens assembly 20 is composed of a first lens 21, a second lens 22, a third lens 23, a fourth lens 24, and a fifth lens 25 sequentially arranged along the same optical axis from the projection surface to the display chip 10. The first lens 21 has a negative optical power;

[0063] The projection lens 100 satisfies: 0.7 < D1 / EFL < 1.05, where EFL represents the focal length of the projection lens 100, and D1 represents the aperture of the first lens 21;

[0064] Define the direction perpendicular to the optical axis as the first direction. The display chip 10 is inclined with respect to the first direction, and the projection surface is inclined with respect to the first direction.

[0065] Specifically, the display chip 10 can be set as a DMD (Digital Micro mirror Device) chip. A plurality of lenses of the lens assembly 20 are sequentially arranged along the same optical axis from the projection surface to the display chip 10, including a first lens 21, a second lens 22, a third lens 23, a fourth lens 24, and a fifth lens 25. The optical centers of each lens are located on the same straight line. An equivalent prism 50 and a protective glass 60 are sequentially arranged between the lens assembly 20 and the display chip 10. Projection light can be emitted from the display chip 10 from the image side to the object side, and sequentially pass through the protective glass 60, the equivalent prism 50, and the lens assembly 20 and then be output to the projection surface to present a projection image.

[0066] Among them, define the direction perpendicular to the optical axis as the first direction, and make the projection surface inclined with respect to the first direction, which can realize that the projection surface is inclined at a certain angle with respect to the image surface. Therefore, it is beneficial to reduce the required deflection angle of the diffuser sheet provided on the projection surface when solving the problem of sunlight backflow. Thus, the adaptability of the projection lens 100 and the diffuser sheet can be improved, which is beneficial to reducing the cost of the projection lens 100 with the diffuser sheet, and thus can reduce the manufacturing cost of the head-up display system.

[0067] Furthermore, in the embodiment of the present utility model, the first lens 21 has a negative optical power. In this way, the first lens 21 can have the effect of diverging light.

[0068] Specifically, the first lens 21 is a plastic aspherical lens with a negative optical power. The second lens 22 has a positive optical power. The optical powers of the third lens 23 and the fourth lens 24 can be positive and negative in sequence, or negative and positive in sequence. The fifth lens 25 is a plastic aspherical lens with a positive optical power. In this way, the optical power of the lens assembly 20 can be reasonably distributed, so that the projection lens 100 has better imaging quality.

[0069] Further, in the embodiment of the present invention, the projection lens 100 satisfies: 0.7 < D1 / EFL < 1.05; where D1 represents the aperture of the first lens 21.

[0070] It can be understood that by limiting the aperture D1 and the focal length EFL of the first lens 21 of the projection lens 100 to satisfy the relational expression 0.7 < D1 / EFL < 1.05, the head size of the projection lens 100 can be ensured.

[0071] In the embodiment of the present invention, the tilt angle range of the display chip 10 relative to the first direction is 0 to 2.1°; the tilt angle range of the projection surface relative to the first direction is 0 to 20°.

[0072] Specifically, the tilt angle range of the display chip 10 relative to the first direction is 0 to 2.1°, for example, 0.7°, 1.4°, 2.1° and any value between 0° and 12.1°. Correspondingly, the tilt angle range of the projection surface relative to the first direction is 0 to 20°, for example, 5°, 10°, 15°, 20° and any value between 0° and 20°. With such a setting, the adaptability of the projection lens 100 and the diffuser can be ensured, and the high-temperature influence and stray light influence on the diffuser of the head-up display system caused by sunlight backflow can be reduced.

[0073] Please refer to Figure 1 , in the embodiment of the present invention, the first lens 21 has a first surface convex towards the projection surface and a second surface concave towards the display chip 10;

[0074] The second lens 22 has a third surface convex towards the projection surface and a fourth surface convex towards the display chip 10;

[0075] The third lens 23 has a fifth surface concave towards the projection surface and a sixth surface concave towards the display chip 10;

[0076] The fourth lens 24 has a seventh surface convex towards the projection surface and an eighth surface convex towards the display chip 10;

[0077] The fifth lens 25 has a ninth surface convex towards the projection surface and a tenth surface convex towards the display chip 10.

[0078] In an embodiment of the present invention, at least the first lens 21 and the fifth lens 25 in the lens assembly 20 are plastic aspherical lenses, and the second lens 22, the third lens 23, and the fourth lens 24 are glass spherical lenses.

[0079] It can be understood that, compared with setting all the lenses of the lens assembly 20 as glass spherical lenses, by setting at least the first lens 21 and the fifth lens 25 as plastic aspherical lenses and the remaining lenses as glass spherical lenses, the present invention realizes a glass-plastic hybrid setting method, which is beneficial to reducing the overall material cost and overall volume of the projection lens 100, and can achieve athermalization, small distortion, and high resolution lens performance while meeting the requirements of vehicle-grade performance.

[0080] In an embodiment of the present invention, the refractive index temperature coefficient of the glass spherical lens material is dn / dt, which satisfies the relationship: dn / dt > 3.5×10-6 / °C.

[0081] Specifically, the second lens 22 is a glass spherical lens, and its refractive index temperature coefficient satisfies the relationship: dn / dt2 > 3.5×10-6 / °C. Further, the third lens 23 and the fourth lens 24 can also be both set as glass spherical lenses, and the refractive index temperature coefficient of the third lens 23 satisfies the relationship: dn / dt3 < 1.0×10-6 / °C. The refractive index temperature coefficient of the fourth lens 24 satisfies the relationship: dn / dt4 > 3.0×10-6 / °C.

[0082] In this way, by limiting the change of the refractive index temperature coefficient of the glass spherical lens material with temperature, the thermal expansion of each lens of the lens assembly 20 can be reasonably matched, which is beneficial to realizing the athermalization design of the projection lens 100 in the environment of -40° to 85°.

[0083] Of course, the technical solution of the present invention is not limited to this. In some embodiments, one of the second lens 22, the third lens 23, and the fourth lens 24 can also be set as a plastic aspherical lens, which is beneficial to reducing the material cost of the projection lens 100 and further improving the lens performance of the projection lens 100.

[0084] In an embodiment of the present utility model, the second lens 22 and the third lens 23 are adhesively connected, and a diaphragm 40 is provided between the third lens 23 and the fourth lens 24. Among them, by adhesively connecting the second lens 22 and the third lens 23 to form a cemented lens, the cemented surface of the two can be a curved surface. Such a setting is conducive to better correcting chromatic aberration to improve the optical performance of the projection lens 100.

[0085] Of course, the technical solution of the present utility model is not limited to the embodiment of the present utility model. The third lens 23 and the fourth lens 24 are adhesively connected, and a diaphragm 40 is provided between the second lens 22 and the third lens 23.

[0086] It can be understood that the setting of the diaphragm 40 can be used to limit the diameter of the projected light passing through, so as to be able to adjust the light flux of the projection lens 100, which is conducive to reducing the interference of stray light and ensuring the imaging quality of the projection lens 100.

[0087] In an embodiment of the present utility model, the refractive index of the first lens 21 is Nd1, and the Abbe number of the first lens 21 is Vd1, satisfying the relationship: Nd1 < 1.65, Vd1 > 45;

[0088] The refractive index of the second lens 22 is Nd2, and the Abbe number of the second lens 22 is Vd2, satisfying the relationship: Nd2 > 1.75, Vd2 < 45;

[0089] The refractive index of the third lens 23 is Nd3, and the Abbe number of the third lens 23 is Vd3, satisfying the relationship: Nd3 > 1.75, Vd3 < 45;

[0090] The refractive index of the fourth lens 24 is Nd4, and the Abbe number of the fourth lens 24 is Vd4, satisfying the relationship: Nd4 > 1.7, Vd4 > 45;

[0091] The refractive index of the fifth lens 25 is Nd5, and the Abbe number of the fifth lens 25 is Vd5, satisfying the relationship: Nd5 < 1.65, Vd5 > 45.

[0092] In an embodiment of the present utility model, the projection lens 100 satisfies the following relationship:

[0093] 3.5 < TTL / EFL < 5;

[0094] 0.19 < BFL / EFL < 0.55;

[0095] Among them, TTL represents the overall optical length of the projection lens 100, EFL represents the focal length of the projection lens 100, and BFL represents the back focal length of the projection lens 100.

[0096] By limiting that the total optical length TTL and the focal length EFL of the projection lens 100 satisfy the relational expression 3.5 < TTL / EFL < 5, the overall length dimension of the projection lens 100 can be ensured; by limiting that the back focal length BFL and the focal length EFL of the projection lens 100 satisfy the relational expression 0.19 < BFL / EFL < 0.55, the back focal length dimension of the projection lens 100 can be ensured.

[0097] The following further introduces the projection lens 100 provided by the present utility model through embodiments.

[0098] Embodiment 1

[0099] As shown in Table 1 are the basic optical design parameters of the projection lens 100 in Embodiment 1 of the present utility model, which include parameters such as surface type, radius of curvature, lens center thickness, air gap, lens refractive index, and lens Abbe number.

[0100] Table 1 Basic Optical Design Parameters

[0101]

[0102]

[0103] For the projection lens 100 provided in the above Embodiment 1, its optical performance is as Figures 2 to 7 shown.

[0104] Among them, Figures 2 to 4 are respectively the MTF graphs of the projection lens 100 provided in Embodiment 1 at the ambient temperatures of 25°C, -40°C, and 85°C. The horizontal axis represents the spatial frequency, and the vertical axis represents the MTF value, which can be used to reflect the imaging clarity. The higher the MTF value, the clearer the corresponding imaging. Figure 5 is the chromatic aberration graph of the projection lens 100 provided in Embodiment 1. Figure 6 is the field curvature and distortion graph of the projection lens 100 provided in Embodiment 1. The left graph therein is the field curvature graph, which can reflect the bending situation of the image plane where the imaging is clear, and the right graph is the distortion graph, which can reflect the deformation situation of the imaging. Figure 7 is the relative illumination graph of the projection lens 100 provided in Embodiment 1 of the present utility model. Among them, the abscissa is the field angle, and the ordinate is the relative illumination, which can feedback the brightness uniformity situation. The higher the value, the better the relative illumination.

[0105] It can be seen therefrom that the projection lens 100 provided in Embodiment 1 can stably operate without defocusing in the temperature environment of -40° to 85°, can achieve low distortion and high resolution, and has good optical performance.

[0106] Embodiment 2

[0107] As shown in Table 2, the basic optical design parameters of the projection lens 100 of Embodiment 1 of the present utility model are presented, including parameters such as surface type, radius of curvature, lens center thickness, air gap, lens refractive index, and lens Abbe number.

[0108] Table 2 Basic Optical Design Parameters

[0109]

[0110]

[0111] Regarding the projection lens 100 provided in the above Embodiment 2, its optical performance is as Figures 8 to 13 shown.

[0112] Among them, Figures 8 to 10 are respectively the MTF graphs of the projection lens 100 provided in Embodiment 2 at ambient temperatures of 25°C, -40°C, and 85°C. The horizontal axis represents the spatial frequency, and the vertical axis represents the MTF value, which can reflect the imaging clarity. The higher the MTF value, the clearer the corresponding image. Figure 11 is the chromatic aberration graph of the projection lens 100 provided in Embodiment 2. Figure 12 is the field curvature and distortion graph of the projection lens 100 provided in Embodiment 2. The left graph is the field curvature graph, which can reflect the curvature of the image plane where the image is clear, and the right graph is the distortion graph, which can reflect the deformation of the image. Figure 13 is the relative illumination graph of the projection lens 100 provided in Embodiment 2 of the present utility model. Among them, the abscissa is the field angle, and the ordinate is the relative illumination, which can feedback the brightness uniformity. The higher the value, the better the relative illumination.

[0113] It can be seen from this that the projection lens 100 provided in Embodiment 2 can work stably without defocusing in the temperature environment of -40° to 85°, can achieve low distortion and high resolution, and has good optical performance.

[0114] Embodiment 3

[0115] As shown in Table 3, the basic optical design parameters of the projection lens 100 of Embodiment 1 of the present utility model are presented, including parameters such as surface type, radius of curvature, lens center thickness, air gap, lens refractive index, and lens Abbe number.

[0116] Table 3 Basic Optical Design Parameters

[0117]

[0118]

[0119] Regarding the projection lens 100 provided in the above Embodiment 3, its optical performance is as Figures 14 to 19 shown.

[0120] Among them, Figures 14 to 16 They are respectively the MTF diagrams of the projection lens 100 provided in Embodiment 3 at ambient temperatures of 25°C, -40°C, and 85°C. The horizontal axis represents the spatial frequency, and the vertical axis represents the MTF value, which can reflect the imaging clarity. The higher the MTF value, the clearer the corresponding imaging. Figure 17 It is the chromatic aberration diagram of the projection lens 100 provided in Embodiment 3. Figure 18 It is the field curvature and distortion diagram of the projection lens 100 provided in Embodiment 3. The left figure therein is the field curvature diagram, which can reflect the bending of the image plane with clear imaging, and the right figure is the distortion diagram, which can reflect the deformation of the imaging. Figure 19 It is the relative illumination diagram of the projection lens 100 provided in Embodiment 3 of the present utility model. Among them, the abscissa is the field angle, and the ordinate is the relative illumination, which can feedback the brightness uniformity. The higher the value, the better the relative illumination.

[0121] It can be seen therefrom that the projection lens 100 provided in Embodiment 3 can stably operate without defocusing in a temperature environment of -40° to 85°, can achieve low distortion and high resolution, and has good optical performance.

[0122] It should be noted that the overall optical architectures of the projection lenses 100 provided in the foregoing Embodiment 1, Embodiment 2, and Embodiment 3 are the same, and for details, reference can be made to Figure 1 the shown optical architecture and optical path diagram of the projection lens.

[0123] The present utility model also proposes a head-up display system, which includes a projection lens 100. The specific structure of the projection lens 100 refers to the above embodiments. Since this theme adopts all the technical solutions of the above-mentioned all embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, and will not be elaborated herein one by one.

[0124] The above is only an exemplary embodiment of the present utility model, and does not limit the patent scope of the present utility model. Any equivalent structural transformation made under the technical concept of the present utility model by using the content of the specification and drawings of the present utility model, or directly / indirectly applied in other related technical fields, is included in the patent protection scope of the present utility model.

Claims

1. A projection lens, characterized in that: The projection lens sequentially includes a display chip, a lens assembly, and a projection surface along the light transmission direction. The lens assembly is composed of a first lens, a second lens, a third lens, a fourth lens, and a fifth lens sequentially arranged along the same optical axis from the projection surface to the display chip. The first lens has a negative optical power; The projection lens satisfies: 0.7 < D1 / EFL < 1.05, where EFL represents the focal length of the projection lens, and D1 represents the aperture of the first lens; Define the direction perpendicular to the optical axis as the first direction. The display chip is inclined with respect to the first direction, and the projection surface is inclined with respect to the first direction.

2. The projection lens according to claim 1, wherein: The inclination angle range of the display chip with respect to the first direction is 0 to 2.1°; The inclination angle range of the projection surface with respect to the first direction is 0 to 20°.

3. The projection lens according to any one of claims 1 to 2, characterized in that: The first lens has a first surface convex toward the projection surface and a second surface concave toward the display chip; The second lens has a third surface convex toward the projection surface and a fourth surface convex toward the display chip; The third lens has a fifth surface concave toward the projection surface and a sixth surface concave toward the display chip; The fourth lens has a seventh surface convex toward the projection surface and an eighth surface convex toward the display chip; The fifth lens has a ninth surface convex toward the projection surface and a tenth surface convex toward the display chip.

4. The projection lens according to claim 3, wherein: The first lens and the fifth lens are plastic aspherical lenses, and the second lens, the third lens, and the fourth lens are glass spherical lenses.

5. The projection lens according to claim 4, wherein: The refractive index temperature coefficient of the glass spherical lens material is dn / dt, satisfying the relationship: dn / dt > 3.5×10-6 / ℃.

6. The projection lens according to claim 5, wherein: The refractive index temperature coefficient of the second lens is dn / dt2, satisfying the relationship: dn / dt2 > 3.5×10-6 / ℃; The refractive index temperature coefficient of the third lens is dn / dt3, satisfying the relationship: dn / dt3 < 1.0×10-6 / ℃ The refractive index temperature coefficient of the fourth lens is dn / dt4, satisfying the relationship: dn / dt4 > 3.0×10-6 / ℃.

7. The projection lens according to claim 3, wherein: The second lens and the third lens are adhesively connected, and a diaphragm is provided between the third lens and the fourth lens; Or, the third lens and the fourth lens are adhesively connected, and a diaphragm is provided between the second lens and the third lens.

8. The projection lens according to claim 3, wherein: The refractive index of the first lens is Nd1, and the Abbe number of the first lens is Vd1, satisfying the relationship: Nd1 < 1.65, Vd1 > 45; The refractive index of the second lens is Nd2, and the Abbe number of the second lens is Vd2, satisfying the relationship: Nd2 > 1.75, Vd2 < 45; The refractive index of the third lens is Nd3, and the Abbe number of the third lens is Vd3, satisfying the relationship: Nd3 > 1.75, Vd3 < 45; The refractive index of the fourth lens is Nd4, and the Abbe number of the fourth lens is Vd4, satisfying the relationship: Nd4 > 1.7, Vd4 > 45; The refractive index of the fifth lens is Nd5, and the Abbe number of the fifth lens is Vd5, which satisfies the relationship: Nd5<1.65, Vd5>45.

9. The projection lens according to claim 3, wherein: The projection lens satisfies the following relationship: 3.5 <TTL / EFL<5; 0.19 <BFL / EFL<0.55; Wherein, TTL represents the total optical length of the projection lens, EFL represents the focal length of the projection lens, and BFL represents the back focus of the projection lens.

10. A head-up display system, characterized in that: The invention comprises the projection lens as claimed in any one of claims 1 to 9.

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