A projection lens and a vehicle-mounted head-up display system
By optimizing the symmetrical structure and lens combination, the aberration problem caused by lens asymmetry in the vehicle HUD system was solved, achieving high-quality imaging and environmental adaptability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- BEIJING JINGWEI HIRAIN TECH CO INC
- Filing Date
- 2025-09-04
- Publication Date
- 2026-08-04
AI Technical Summary
In existing vehicle-mounted HUD imaging systems, the PGU system has an asymmetrical lens layout, resulting in significant asymmetric aberrations such as coma, field curvature, and distortion, leading to poor imaging performance.
The projection lens employs a symmetrical structure, including a coaxially arranged lens combination, using a combination of positive and negative focal length lenses, optimizing lens materials and focal length distribution, and combining cemented lenses and a symmetrical layout to reduce asymmetric aberrations.
It effectively reduces aberrations such as coma, astigmatism, field curvature, and distortion, improves imaging quality, and ensures the stability and imaging effect of the system under extreme temperature environments.
Smart Images
Figure CN224594905U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of optical imaging technology, and in particular to a projection lens and a vehicle head-up display system. Background Technology
[0002] A vehicle-mounted HUD (Head-Up Display) imaging system is a technology that projects vehicle information onto the windshield or a separate transparent screen directly in front of the driver. Drivers do not need to look down at the information displayed on visual terminals such as mobile phone navigation, car instrument panel, and car center console screen, making it easier to concentrate on driving and reducing the probability of road traffic accidents.
[0003] In existing vehicle HUD imaging systems, the PGU (Picture Generation Unit) system is very complex. The asymmetrical lens layout of the existing PGU results in large asymmetric aberrations such as coma, field curvature, and distortion, which leads to poor imaging performance as an image source for car head-up displays and in-vehicle projectors. Utility Model Content
[0004] In view of this, the present invention provides a projection lens with a symmetrical structure arrangement, which can effectively reduce asymmetric aberrations such as coma, astigmatism, field curvature, and distortion.
[0005] This utility model also provides a vehicle head-up display system including the above-mentioned projection lens.
[0006] To achieve the above objectives, this utility model provides the following technical solution:
[0007] A projection lens for use in a vehicle head-up display system includes: a front group of projection lenses, an aperture stop, and a rear group of projection lenses arranged coaxially from the projection surface to the image surface.
[0008] The front group of the projection objective lens includes: a first lens, a second lens, and a third lens arranged coaxially from the projection surface to the aperture;
[0009] The rear group of the projection lens includes: a fourth lens, a fifth lens, and a sixth lens arranged coaxially from the aperture to the image plane;
[0010] The first lens, the second lens, the fifth lens, and the sixth lens are all positive focal length lenses, while the third lens and the fourth lens are negative focal length lenses.
[0011] Preferably, the optical power of the first lens is a first optical power, the optical power of the second lens is a second optical power, and the optical power of the third lens is a third optical power, wherein the sum of the first optical power, the second optical power, and the third optical power is greater than zero.
[0012] Preferably, the optical power of the fourth lens is the fourth optical power, the optical power of the fifth lens is the fifth optical power, and the optical power of the sixth lens is the sixth optical power, wherein the sum of the fourth optical power, the fifth optical power, and the sixth optical power is greater than zero.
[0013] Preferably, the overall focal length of the rear group of the projection objective lens, which is composed of the fourth lens, the fifth lens, and the sixth lens, is in the range of 8.5 to 15 mm.
[0014] Preferably, the first lens and the second lens are meniscus lenses; and / or,
[0015] The third lens is a meniscus lens.
[0016] Preferably, the fourth lens and the fifth lens are cemented together to form a cemented lens.
[0017] Preferably, the first lens, the third lens, and the fourth lens are all made of heavy flint glass;
[0018] The second lens and the sixth lens are both made of lanthanide glass, and the fifth lens is made of crown glass.
[0019] Preferably, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens are all spherical lenses.
[0020] A vehicle-mounted head-up display system includes a projection surface and an image surface, and also includes a projection lens as described above;
[0021] The plane containing the projection surface, the perpendicular plane of the optical axis of the projection lens, and the plane containing the image plane intersect on a straight line.
[0022] Preferably, the normal of the image plane and the optical axis of the projection lens are set at an angle.
[0023] As can be seen from the above technical solution, the projection lens provided by this utility model adopts a symmetrical structure. This symmetrical structure manifests in two aspects: firstly, three lenses are respectively arranged on both sides of the aperture stop, which can effectively reduce asymmetric aberrations such as coma, astigmatism, field curvature, and distortion; secondly, the focal lengths of the lenses are symmetrically arranged, wherein the first, second, fifth, and sixth lenses are all positive focal length lenses, and the third and fourth lenses are negative focal length lenses, which is beneficial to improving the imaging effect. In summary, this projection lens ensures good system imaging effect while reducing system aberrations.
[0024] This utility model also provides a vehicle head-up display system. Since it uses the above-mentioned projection lens, it has corresponding beneficial effects, which can be referred to in the previous description and will not be repeated here. Attached Figure Description
[0025] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0026] Figure 1 This is a diagram of the optical architecture of the projection lens;
[0027] Figure 2 This is the optical architecture and optical path diagram of the projection lens;
[0028] Figure 3 This is a diagram showing the fit between the projection lens and the projection surface.
[0029] Figure 4 This is a schematic diagram showing the coordination of the various components of this vehicle head-up display system;
[0030] Figure 5 This is a dot diagram of an embodiment of the projection lens;
[0031] Figure 6 This is a ray fan diagram of the projection lens embodiment;
[0032] Figure 7 This is a distortion diagram of this projection lens embodiment;
[0033] Figure 8 This is the MTF curve of the projection lens embodiment at room temperature (20°C);
[0034] Figure 9 This is the MTF curve of the projection lens embodiment at room temperature (-40℃);
[0035] Figure 10 This is the MTF curve of this projection lens embodiment at room temperature (105°C).
[0036] The meanings of the various reference numerals in the figure are as follows:
[0037] 1 is the first lens, 2 is the second lens, 3 is the third lens, 4 is the fourth lens, 5 is the fifth lens, 6 is the sixth lens, 7 is the TIR prism, 8 is the aperture stop, 9 is the glass cover plate, 10 is the image plane, and 11 is the projection plane. Detailed Implementation
[0038] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.
[0039] The projection lens provided in this embodiment of the utility model is applied to an in-vehicle head-up display system, such as... Figure 1 and Figure 3 As shown,
[0040] Includes: a front group of projection lenses, an aperture stop 8, and a rear group of projection lenses arranged coaxially from projection plane 11 to image plane 10;
[0041] The front group of the projection lens includes: a first lens 1, a second lens 2 and a third lens 3 arranged coaxially from the projection surface 11 to the aperture stop 8;
[0042] The rear group of the projection lens includes: a fourth lens 4, a fifth lens 5, and a sixth lens 6 arranged coaxially from the aperture stop 8 to the image plane 10;
[0043] Among them, the first lens 1, the second lens 2, the fifth lens 5 and the sixth lens 6 are all positive focal length lenses, while the third lens 3 and the fourth lens 4 are negative focal length lenses.
[0044] In the above technical solution, the projection lens adopts a symmetrical structure. This symmetrical structure has two aspects: first, three lenses are respectively arranged on both sides of the aperture stop 8, which can effectively reduce asymmetric aberrations such as coma, astigmatism, field curvature, and distortion; second, the focal lengths of the lenses are symmetrically arranged, with the first lens 1, the second lens 2, the fifth lens 5, and the sixth lens 6 all being positive focal length lenses, and the third lens 3 and the fourth lens 4 being negative focal length lenses, thus improving the imaging effect. In summary, this projection lens ensures good system imaging while reducing system aberrations.
[0045] In one optional technical solution, the optical power of the first lens 1 is the first optical power, the optical power of the second lens 2 is the second optical power, and the optical power of the third lens 3 is the third optical power, wherein the sum of the first, second, and third optical powers is greater than zero. Specifically, since both the first lens 1 and the second lens 2 are positive focal length lenses, both the second and second optical powers are greater than zero; the third lens 3 is a negative focal length lens, therefore the third optical power is less than zero. In summary, the total optical power of the front group of this projection lens is greater than zero.
[0046] In one optional technical solution, the optical power of the fourth lens 4 is the fourth optical power, the optical power of the fifth lens 5 is the fifth optical power, and the optical power of the sixth lens 6 is the sixth optical power, wherein the sum of the fourth, fifth, and sixth optical powers is greater than zero. Specifically, since both the fifth lens 5 and the sixth lens 6 are positive focal length lenses, their fifth and sixth optical powers are both greater than zero; the sixth lens 6 is a negative focal length lens, therefore its sixth optical power is less than zero. In summary, the total optical power of the front group of this projection lens is greater than zero.
[0047] The above technical solution is optimized so that the overall focal length of the rear group of the projection objective lens, which consists of the fourth lens 4, the fifth lens 5 and the sixth lens 6, ranges from 8.5 to 15 mm.
[0048] In one alternative technical solution, the first lens 1 and the second lens 2 are meniscus lenses (specifically, meniscus lenses with a positive focal length), and / or, the third lens 3 is a meniscus lens (specifically, a meniscus lens with a negative focal length). Furthermore, the meniscus lens possesses flexible aberration correction capabilities and structural compactness due to its asymmetrical curved surface, which is beneficial for aberration optimization and overall compactness of the projection lens.
[0049] In one of the alternative technical solutions, such as Figure 2 and Figure 3 As shown, the fourth lens 4 and the fifth lens 5 are cemented together to form a cemented lens. In use, the cemented lens can correct aberrations (spherical aberration correction and chromatic aberration correction) and optimize optical performance (improving resolution and increasing the field of view).
[0050] In an alternative technical solution, the first lens 1, the third lens 3, and the fourth lens 4 are all made of heavy flint glass (low Abbe number glass). Since the refractive index of heavy flint glass is usually between 1.6 and 1.9, the first lens 1, the third lens 3, and the fourth lens 4 all have high refractive index.
[0051] Both the second lens 2 and the sixth lens 6 are made of lanthanide glass (the Abbe number of lanthanide glass is between that of heavy flint glass and heavy crown glass). Both the second lens 2 and the sixth lens 6 made of lanthanide glass have high refractive index, low dispersion, and high temperature stability, so as to improve the imaging quality of the projection lens.
[0052] The fifth lens 5 is made of crown glass (high Abbe number glass). The fifth lens 5, made of crown glass, has a high refractive index and low dispersion to improve the image quality of the projection lens.
[0053] In the above technical solution, the fourth lens 4, made of heavy flint glass, and the fifth lens 5, made of heavy crown glass, work together to compensate for each other's dispersion characteristics, significantly reducing the focal length difference between red light (long wavelength) and blue light (short wavelength), thus further improving the image quality of the projection lens. It should also be noted that in this technical solution, through careful selection of lens materials, consideration of the number of lenses, and the symmetrical arrangement of the lenses, the projection lens exhibits excellent thermal stability; even under extreme high and low temperature environments, the MTF remains essentially unchanged. Figures 8-10 As shown.
[0054] In one alternative technical solution, the Abbe numbers of the first lens 1, the second lens 2, and the third lens 3 are symmetrically arranged with the Abbe numbers of the fourth lens 4, the fifth lens 5, and the sixth lens 6. For example, if the first lens 1 has a high Abbe number, then the fourth lens 4 also has a high Abbe number; if the first lens 1 has a low Abbe number, then the fourth lens 4 also has a low Abbe number. This symmetrical arrangement of Abbe numbers significantly improves image quality, simplifies the system structure, and enhances environmental adaptability. Furthermore, the Abbe number of each lens can be selected according to actual needs.
[0055] In one alternative technical solution, to reduce processing difficulty while effectively controlling costs and ensuring excellent imaging performance, the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, and the sixth lens 6 are all spherical lenses. This avoids the problems associated with existing projection lenses that use plastic aspherical lenses (using plastic aspherical lenses increases the difficulty of lens processing and inspection, and correspondingly raises costs; furthermore, plastic is very sensitive to temperature changes, especially in the harsh ambient temperatures of in-vehicle systems, where image quality deteriorates sharply).
[0056] A vehicle head-up display system includes a projection surface 11 and an image surface 10, and also includes the aforementioned projection lens;
[0057] like Figure 4 As shown, the plane where the projection surface 11 is located, the perpendicular plane of the optical axis of the projection lens, and the plane where the image plane 10 is located intersect on a straight line, so that the projection lens conforms to the Schahm lens principle and can clearly image on the tilted projection surface 11. This effectively reduces the size of the projection lens while ensuring excellent optical performance.
[0058] To optimize the above technical solution and enable imaging on the tilted projection surface 11, the normal of the image plane 10 and the optical axis of the projection lens are set at an angle, such as... Figure 1 and Figure 2 As shown.
[0059] In one optional technical solution, the DMD chip reflects the light beam from the illumination end in an open state, then enters the projection lens through the TIR prism 7. After the beam is shaped, a clear image is displayed on the projection surface 11 at a fixed position. It can be used as an image source for HUD (Head-Up Display) and vehicle-mounted projectors.
[0060] The technical features mentioned above, those to be mentioned below, and those shown individually in the accompanying drawings can be combined arbitrarily, provided that the combined technical features are not contradictory. All feasible combinations of features are the technical content explicitly described herein. Any one of the multiple sub-features contained in the same statement can be applied independently, without necessarily being applied together with other sub-features.
[0061] The following is a further description of this solution with reference to specific embodiments:
[0062] In one specific embodiment, the basic optical parameters of the projection lens, image plane 10, and object plane include surface type, radius of curvature, lens center thickness, air gap, material, and aperture. Specific parameters are shown in the table below.
[0063]
[0064] In the above scheme, the plane numbers are arranged sequentially from projection plane 11 to image plane 10.
[0065] A projection lens made using the aforementioned specific optical parameters is used in a specific implementation, such as... Figure 5 As shown, this satisfies the system's aberration requirements. (As...) Figure 6 As shown, in this embodiment, aberrations such as astigmatism and spherical aberration are within an acceptable range, achieving the expected performance. Figure 7 As shown, in this embodiment, the field curvature / distortion meets the imaging requirements of the optical system.
[0066] Projection lenses made using the specific optical parameters described above, such as Figure 8 As shown, the imaging quality in the embodiment with an ambient temperature of 20°C is sufficient to meet the imaging quality requirements. Figure 9 As shown, in the embodiment with an ambient temperature of -40°C, the image quality is sufficient to meet the image quality requirements. Figure 10As shown, in the embodiment with an ambient temperature of 105°C, the image quality is sufficient to meet the image quality requirements. Therefore, the projection lens exhibits stable thermal performance, maintaining a essentially unchanged MTF even under extreme high and low temperature environments, and ensuring excellent imaging results in the harsh temperature environment of an automotive vehicle. The light source of this projection lens is compatible with both LCOS (liquid crystal on silicon) illumination units and DLP (Digital Light Processing) illumination units.
[0067] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.
[0068] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A projection lens applied to a vehicle-mounted head-up display system, characterized in that, include: The front group of projection lenses, the aperture (8), and the rear group of projection lenses are arranged in sequence and coaxially from the projection plane (11) to the image plane (10); The front group of the projection lens includes: a first lens (1), a second lens (2) and a third lens (3) arranged in sequence and coaxially from the projection surface (11) to the aperture stop (8); The rear group of the projection lens includes: a fourth lens (4), a fifth lens (5) and a sixth lens (6) arranged in sequence and coaxially from the aperture stop (8) to the image plane (10); Among them, the first lens (1), the second lens (2), the fifth lens (5) and the sixth lens (6) are all positive focal length lenses, and the third lens (3) and the fourth lens (4) are negative focal length lenses.
2. The projection lens according to claim 1, characterized in that The first lens (1) has a first optical power, the second lens (2) has a second optical power, and the third lens (3) has a third optical power, wherein the sum of the first optical power, the second optical power and the third optical power is greater than zero.
3. The projection lens of claim 1, wherein The optical power of the fourth lens (4) is the fourth optical power, the optical power of the fifth lens (5) is the fifth optical power, and the optical power of the sixth lens (6) is the sixth optical power, wherein the sum of the fourth optical power, the fifth optical power and the sixth optical power is greater than zero.
4. The projection lens according to claim 3, characterized in that The overall focal length of the rear group of the projection objective lens, which consists of the fourth lens (4), the fifth lens (5) and the sixth lens (6), ranges from 8.5 to 15 mm.
5. The projection lens of claim 1, wherein The first lens (1) and the second lens (2) are meniscus lenses; and / or, The third lens (3) is a meniscus lens.
6. The projection lens of claim 1, wherein The fourth lens (4) and the fifth lens (5) are cemented together to form a cemented lens.
7. The projection lens of claim 1, wherein The first lens (1), the third lens (3) and the fourth lens (4) are all made of heavy flint glass; The second lens (2) and the sixth lens (6) are both made of lanthanide glass, and the fifth lens (5) is made of crown glass.
8. The projection lens according to claim 1, characterized in that, The first lens (1), the second lens (2), the third lens (3), the fourth lens (4), the fifth lens (5) and the sixth lens (6) are all spherical lenses.
9. A head-up display system for a vehicle, comprising a projection surface (11) and an image surface (10), characterized in that: It also includes the projection lens as described in any one of claims 1-8; The plane containing the projection surface (11), the perpendicular plane of the optical axis of the projection lens, and the plane containing the image plane (10) intersect on a straight line.
10. The vehicle head-up display system of claim 9, wherein, The normal of the image plane (10) and the optical axis of the projection lens are set at an angle.