DLP projection lens applied to automobile external illumination

Abstract

The invention provides a DLP projection lens applied to automobile external illumination, and relates to the technical field of optical imaging. Comprising a first group, a diaphragm, a second group, an equivalent prism, a chip protection lens and a display chip which are sequentially arranged from an object space side to an image space side along an optical axis, the display chip is used for emitting light, the equivalent prism is used for receiving the emitted light and transmitting the emitted light to the second group, the second group is used for performing spherical aberration correction, chromatic aberration correction and field curvature correction on the emitted light to obtain first optimized light, and the first optimized light penetrates through the diaphragm to reach the first lens group; the first group is used for correcting coma, astigmatism and curvature of field of the first optimized light again to obtain second optimized light for imaging in a target area; according to the invention, the technical problem that the existing projection lens cannot meet the requirements of vehicle gauge grade weather resistance, large target surface, high luminous efficiency, dynamic thermal stability and compact design at the same time is solved.

Description

Technical Field

[0001] This invention relates to the field of optical imaging technology, and in particular to a DLP projection lens for use in automotive exterior lighting. Background Technology

[0002] DLP automotive dynamic projection lighting is a technology that evolved from stage lighting and digital cinema projection. Its core technology, DLP (Digital Light Processing), was initially mainly used in professional projectors and digital cinemas. In the 21st century, with the increasing demands for intelligent and interactive vehicles, DLP technology began to be applied to the external lighting systems of high-end cars. It can project complex graphics, warning messages, and even custom animations onto the road surface around the vehicle, realizing the functional evolution of lighting from "seeing" to "communication and interaction."

[0003] The DMD (Digital Micromirror Device) is the core of DLP projection. As a digital light modulator, it features high reliability, high brightness, and fast response. Compared to traditional matrix LED lighting, DLP solutions can achieve true pixel-level, programmable dynamic light patterns and image generation.

[0004] Dynamic ground projection is a core application scenario of DLP technology and represents the future development direction of automotive lighting systems, moving from passive lighting to active interaction. It also signifies the evolution of adaptive high-beam technology towards a more advanced and user-friendly approach. By precisely controlling millions of micromirrors, DLP systems can transform the vehicle's external environment into a programmable "canvas." Its applications have transcended traditional lighting, expanding the functional boundaries of both interior and exterior automotive lights. Through precise control of millions of micromirrors, DLP lights can achieve glare-free high beams, lane departure warnings, and pedestrian warning projections, deeply integrating lighting with intelligent driving environmental perception. This is a crucial component of next-generation intelligent vehicle interaction and safety.

[0005] Current automotive dynamic projection lighting mostly employs matrix LEDs or multi-mirror scanning solutions. While these can achieve basic adaptive high beams and simple pattern projection, their low pixel accuracy and limited pattern flexibility make it difficult to achieve high-resolution, programmable, complex dynamic lighting and interactive functions. Furthermore, the optical system lacks the ability to control complex light patterns, making it difficult to simultaneously meet the requirements of high brightness, high uniformity, and small size, thus failing to meet the demands of future intelligent interactive lighting for refined optical performance.

[0006] The core of DLP projection technology lies in digital micromirror technology, a technology already highly mature in other fields, possessing excellent optoelectronic performance and reliability. This technology enables true pixel-level dynamic lighting, featuring high resolution, high brightness, fast response, and fully digital programmable capabilities, allowing lighting systems to be upgraded into interactive visual interfaces. However, applying DLP technology to the harsh automotive environment still faces challenges: existing projection lenses struggle to simultaneously meet the requirements of automotive-grade weather resistance, large target surface with high luminous efficiency, dynamic thermal stability, and compact design, limiting the performance release and large-scale application of DLP in automotive lighting. Summary of the Invention

[0007] In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a DLP projection lens for automotive exterior lighting. This invention solves the technical problem that existing projection lenses cannot simultaneously meet the requirements of automotive-grade weather resistance, large target surface and high light efficiency, dynamic thermal stability and compact design.

[0008] To achieve the above objectives, the present invention provides the following solution: A DLP projection lens for automotive exterior lighting includes: The first group, aperture, second group, equivalent prism, chip protection mirror and display chip are arranged sequentially along the optical axis from the object side to the image side; The display chip is used to emit light, the equivalent prism is used to receive the emitted light and transmit the emitted light to the second group, the second group is used to correct spherical aberration, chromatic aberration and field curvature of the emitted light to obtain a first optimized light and pass through the aperture to reach the first lens group, the first group is used to correct coma, astigmatism and field curvature of the first optimized light again to obtain a second optimized light to image the target area; The first lens group includes: a first lens and a second lens; The second lens group includes: a third lens, a fourth lens, a fifth lens, and a sixth lens.

[0009] Preferably, the first lens, the fifth lens, and the sixth lens are lenses with positive optical power.

[0010] Preferably, the second lens is a lens with negative optical power.

[0011] Preferably, the third and fourth lenses are combined to form a negative optical power cemented doublet lens.

[0012] Preferably, the ratio of the focal length of the lens in the first lens group to the focal length of the DLP projection lens is 2.789.

[0013] Preferably, the focal length ratio of the first lens to the first lens group is 0.647, and the focal length ratio of the second lens to the first lens group is 0.911.

[0014] Preferably, the ratio of the focal length of the lens in the second lens group to the focal length of the DLP projection lens is 0.614.

[0015] Preferably, the focal length ratio of the cemented doublet lens to the second lens group is -2.982; the focal length ratio of the fifth lens to the second lens group is 2.253; and the focal length ratio of the sixth lens to the second lens group is 2.499.

[0016] The present invention discloses the following technical effects: This invention provides a DLP projection lens for automotive exterior lighting, comprising a first group, an aperture stop, a second group, an equivalent prism, a chip protection lens, and a display chip arranged sequentially along the optical axis from the object side to the image side; the display chip is used to emit light, the equivalent prism is used to receive the emitted light and transmit the emitted light to the second group, the second group is used to correct spherical aberration, chromatic aberration, and field curvature of the emitted light to obtain a first optimized light that passes through the aperture stop to reach the first lens group, the first group is used to further correct coma, astigmatism, and field curvature of the first optimized light to obtain a second optimized light for imaging in a target area; the first lens group includes a first lens and a second lens; the second lens group includes a third lens, a fourth lens, a fifth lens, and a sixth lens. The lens of this invention has a total length of less than 35mm, enabling a compact and mechanically robust optical architecture within the limited space of automotive headlights, rearview mirrors, and other similar applications. With an F-number less than 2.2, the lens's receiving angle is slightly larger than the DMD's emission angle, ensuring that most of the modulated light is effectively captured, thus avoiding "pupil shearing" loss caused by aperture mismatch from an optical principle perspective. The relative illumination across the entire field of view is above 90%, and the MTF across the entire field of view is above 0.7, resulting in excellent image quality. Distortion is within 1.5%, and TV distortion is within 1%, demonstrating excellent distortion correction. The lens uses all-glass elements, effectively reducing lens temperature drift and maintaining excellent image quality even at temperatures ranging from -40℃ to 105℃. The structure is simple, with low tolerance sensitivity, using only 6 lenses, effectively reducing lens cost and assembly difficulty. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a projection diagram of a DLP projection lens for automotive exterior lighting provided in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of a DLP projection lens structure for automotive exterior lighting provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the light path provided in an embodiment of the present invention; Figure 4 Spatial frequency MTF diagram provided for embodiments of the present invention; Figure 5 A lateral color difference diagram provided in an embodiment of the present invention; Figure 6 Field distortion diagram provided for embodiments of the present invention; Figure 7 The relative illumination map is provided for an embodiment of the present invention.

[0019] Figure label: 100 - First lens group, 110 - First lens, 120 - Second lens, 200 - Second lens group, 210 - Aperture stop, 220 - Cemented doublet lens, 221 - Third lens, 222 - Fourth lens, 230 - Fifth lens, 240 - Sixth lens, 300 - Equivalent prism, 400 - Chip protection lens, 500 - Display chip. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0022] like Figure 1-3As shown, the present invention provides a DLP projection lens for automotive exterior lighting, comprising: a first group, an aperture stop 210, a second group, an equivalent prism 300, a chip protection lens 400, and a display chip 500 arranged sequentially along the optical axis from the object side to the image side; the display chip 500 is used to emit light, the equivalent prism 300 is used to receive the emitted light and transmit the emitted light to the second group, the second group is used to correct spherical aberration, chromatic aberration, and field curvature of the emitted light to obtain a first optimized light that passes through the aperture stop 210 to reach the first lens group 100, the first group is used to correct coma, astigmatism, and field curvature of the first optimized light again to obtain a second optimized light for imaging in a target area; the first lens group 100 includes: a first lens 110 and a second lens 120; the second lens group 200 includes: a third lens 221, a fourth lens 222, a fifth lens 230, and a sixth lens 240.

[0023] Furthermore, the first lens 110, the fifth lens 230, and the sixth lens 240 are lenses with positive optical power; the second lens 120 is a lens with negative optical power; the third lens 221 and the fourth lens 222 are combined to form a negative optical power cemented doublet lens 220; the ratio of the focal length of the first lens group 100 to the focal length of the DLP projection lens is 2.789; the ratio of the focal length of the first lens 110 to the focal length of the first lens group 100 is 0.647; the ratio of the focal length of the second lens 120 to the focal length of the first lens group 100 is 0.911; the ratio of the focal length of the second lens group 200 to the focal length of the DLP projection lens is 0.614; the ratio of the focal length of the cemented doublet lens 220 to the focal length of the second lens group 200 is -2.982; the ratio of the focal length of the fifth lens 230 to the focal length of the second lens group 200 is 2.253; and the ratio of the focal length of the sixth lens 240 to the focal length of the second lens group 200 is 2.499.

[0024] The specific parameters of the DLP projection lens objective system are shown in Table 1: Table 1

[0025] The coefficients of aspherical lenses are shown in Table 2:

[0026] Furthermore, such as Figure 4As shown, MTF (Modulation Transfer Function) is currently the most accurate and scientific evaluation standard for lenses. The vertical axis represents contrast ratio; the closer it is to 1, the better the lens image quality. The horizontal axis represents resolution, measured in line pairs per millimeter. The image source pixel size used in this embodiment is 7.6μm, corresponding to a design resolution of 66 line pairs per millimeter. Projection lenses generally require an MTF value of at least 0.3 for each field of view at the design resolution, while in this embodiment, the MTF values ​​for each field of view at each zoom position are all above 0.7.

[0027] Figure 5 This is a chromatic aberration diagram of the lens, with the vertical axis representing the image height field of view value and the horizontal axis representing the numerical value, in micrometers. The diagram plots the chromatic aberration values ​​for each field of view between blue, red, and green light (dominant wavelengths) based on the dominant wavelength. Projection lenses generally require the chromatic aberration value to be within one pixel size. In this embodiment, the chromatic aberration is controlled within 2μm, which is less than 0.3 pixels (pixel size 7.6µm).

[0028] Figure 6 In the diagram, the left image is the field curvature evaluation diagram, and the right image is the distortion evaluation diagram. The vertical axis represents the field of view angle of the lens. The horizontal axis of the field curvature diagram represents the magnitude of the field curvature value, and the horizontal axis of the distortion diagram represents the distortion value. Distortion is a very important indicator for projection lenses, generally requiring control within 3%, while TV distortion is required to be controlled within 1%. The distortion shape of the embodiments in this application enables the system TV distortion to meet the requirements, with system distortion within 1.5% and TV distortion within 1%.

[0029] Figure 7 This is a relative illumination diagram of the lens. High relative illumination ensures consistent brightness from the center to the edge of the projection. Insufficient brightness in the edge areas directly affects the clarity and security of information recognition. In conventional commercial / consumer DLP projection systems, the relative illumination at the edge of the projection lens is typically between 60% and 80%; the relative illumination of the embodiment in this application is greater than 92%.

[0030] Furthermore, the lens has an F.N. of 2.0 to 2.4; it employs a double Gaussian structure, with the second lens element being an aspherical lens; it uses a 0.3-inch DMD chip, DLP3021; ​​the third lens 221 and the fourth lens 222 are combined to form a cemented doublet lens 220, which effectively eliminates system chromatic aberration; all lenses are glass lenses, exhibiting good thermal stability and excellent image quality even at temperatures ranging from -40℃ to 105℃.

[0031] Furthermore, in the implementation, the optical lens satisfies the following condition: 1.58 <ENPD / IH<1.81 (1) Wherein, EPND represents the aperture of the optical lens, and IH represents the actual half-image height of the optical lens.

[0032] When condition (1) is met, a reasonable balance between the large light transmission capacity and the large imaging surface of the lens can be achieved.

[0033] In the implementation method, the optical lens satisfies the following condition: 0.45mm -1 <T L / f / IH<0.62 mm -1 (2) Among them, T L The optical total length of the optical lens is represented by f, the effective focal length of the optical lens is represented by f, and the actual half-image height of the optical lens is represented by IH.

[0034] When condition (2) is satisfied, the relationship between the total length of the lens and the resolving power can be reasonably balanced. L When the / f / IH value exceeds the upper limit, the overall length of the lens is too large, or in other words, if the overall length is shortened, the image height will be insufficient; T L When the value of / f / IH exceeds the lower limit, the lens aberration correction becomes difficult due to the excessive optical focal length of each lens, and the resolving power decreases significantly.

[0035] In the implementation method, the optical lens satisfies the following condition: 14.2mm< IH / tanθ<18.7mm (3) Where f represents the effective focal length of the optical lens, and θ represents the half field of view of the optical lens.

[0036] When condition (3) is met, the distortion of the optical lens can be reasonably limited, reducing the difficulty of distortion correction. When the value of IH / tanθ exceeds the lower limit, the distortion of the lens will increase in the negative direction; when the value of IH / tanθ exceeds the upper limit, the distortion of the lens will increase in the positive direction.

[0037] In the implementation method, the optical lens satisfies the following condition: CRA<2° (4) Wherein, CRA represents the angle of incidence of the principal ray on the imaging plane of the optical lens.

[0038] When condition (4) is met, it can be well matched with the DMD chip and achieve good projection effect.

[0039] 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.

[0040] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A DLP projection lens for automotive exterior lighting, characterized in that, include: The first group, aperture, second group, equivalent prism, chip protection mirror and display chip are arranged sequentially along the optical axis from the object side to the image side; The display chip is used to emit light, the equivalent prism is used to receive the emitted light and transmit the emitted light to the second group, the second group is used to correct spherical aberration, chromatic aberration and field curvature of the emitted light to obtain a first optimized light and pass through the aperture to reach the first lens group, the first group is used to correct coma, astigmatism and field curvature of the first optimized light again to obtain a second optimized light to image the target area; The first lens group includes: a first lens and a second lens; The second lens group includes: a third lens, a fourth lens, a fifth lens, and a sixth lens.

2. The DLP projection lens for automotive exterior lighting according to claim 1, characterized in that, The first lens, the fifth lens, and the sixth lens are lenses with positive optical power.

3. A DLP projection lens for automotive exterior lighting according to claim 1, characterized in that, The second lens is a negative optical power lens.

4. A DLP projection lens for automotive exterior lighting according to claim 1, characterized in that, The third and fourth lenses combine to form a negative optical power cemented doublet.

5. A DLP projection lens for automotive exterior lighting according to claim 1, characterized in that, The ratio of the focal length of the lens in the first lens group to the focal length of the DLP projection lens is 2.

789.

6. A DLP projection lens for automotive exterior lighting according to claim 1, characterized in that, The focal length ratio of the first lens to the first lens group is 0.647, and the focal length ratio of the second lens to the first lens group is 0.

911.

7. A DLP projection lens for automotive exterior lighting according to claim 1, characterized in that, The ratio of the focal length of the second lens group to the focal length of the DLP projection lens is 0.

614.

8. A DLP projection lens for automotive exterior lighting according to claim 1, characterized in that, The focal length ratio of the cemented doublet lens to the second lens group is -2.982; the focal length ratio of the fifth lens to the second lens group is 2.253; and the focal length ratio of the sixth lens to the second lens group is 2.499.

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