Large-aperture five-piece projection lens and vehicle lamp using same

Abstract

The utility model discloses a large-aperture five-piece projection lens and a vehicle lamp using the same. The large-aperture five-piece projection lens comprises a first lens, a first diaphragm, a second lens, a third lens, a fourth lens, a second diaphragm, a fifth lens and a DMD which are sequentially arranged from an image side to an object side along an optical axis direction, wherein the focal length f1 of the first lens and the focal length EFL of the large-aperture five-piece projection lens meet the conditional expression: 1 < f1 / EFL < 2; the focal length f2 of the second lens and the focal length EFL of the large-aperture five-piece projection lens meet the conditional expression: 0.5 < f2 / EFL < 1.5; the focal length f3 of the third lens and the focal length EFL of the large-aperture five-piece projection lens meet the conditional expression: 1.7 < f3 / EFL < 2; the focal length f4 of the fourth lens and the focal length EFL of the large-aperture five-piece projection lens meet the conditional expression that f4 / EFL is greater than 1.3 and less than 1.8; and the focal length f5 of the fifth lens and the focal length EFL of the large-aperture five-piece projection lens meet the conditional expression: 0.5 < f5 / EFL < 1.2.

Description

Technical Field

[0001] The utility model relates to the technical field of vehicle lamps, in particular to a large-aperture five-piece projection lens and a vehicle lamp using the same. Background Technique

[0002] With the development of themes such as intelligent sensing and safe driving in the automotive field, as the "glasses" for night driving - the headlamp plays an increasingly important role in driving safety, and its functions have gradually evolved from single lighting to adaptive high beam, and now to more intelligent and pixelated projection vehicle lamps.

[0003] At present, pixelated and intelligent projection vehicle lamps mainly rely on digital light processing (DLP) projection technology and high-pixel LEDs. Among them, DLP technology has been applied in the projector field for many years. As a projection vehicle lamp, it can achieve high-definition projection in the millions, and mainly consists of a lighting system, a light modulator (DMD), and a projection lens. Due to system structure limitations, the projection lens needs to have a long back focal length. To improve the system light efficiency, the projection lens needs to have a large aperture. These requirements pose greater challenges to the design of the projection lens. The five-piece projection lens adopted in the prior art can achieve a modulation transfer function (MTF) of more than 0.5, which can achieve higher image quality. However, to control the chromatic aberration and thermal stability of the system, some glass materials with special temperature characteristics are usually required, resulting in a relatively high overall cost. If a five-piece glass-plastic hybrid structure is adopted, the imaging quality will be insufficient and more sensitive to tolerances.

[0004] Therefore, for the five-piece projection lens applied in the DLP optical system, how to balance high-quality imaging effects, reduce production costs, and reduce the weight of the product is a technical difficulty that needs to be overcome. Summary of the Utility Model

[0005] The first object of the utility model is to provide a large-aperture five-piece projection lens to solve the technical problem of balancing cost reduction and imaging effect improvement.

[0006] The second object of the utility model is to provide a vehicle lamp to solve the technical problem that the lens used can balance weight reduction and imaging effect improvement.

[0007] The large-aperture five-piece projection lens of the utility model is realized as follows:

[0008] A large-aperture five-piece projection lens includes: a first lens, a first diaphragm, a second lens, a third lens, a fourth lens, a second diaphragm, a fifth lens, and a DMD arranged in sequence from the image side to the object side along the optical axis direction; where

[0009] The first lens has a positive optical power; the second lens has a negative optical power; the third lens has a positive optical power, the fourth lens has a negative optical power, and the fifth lens has a positive optical power;

[0010] The focal length f1 of the first lens and the focal length EFL of the large-aperture five-lens projection lens satisfy the conditional formula: 1 < |f1 / EFL| < 2; the focal length f2 of the second lens and the focal length EFL of the large-aperture five-lens projection lens satisfy the conditional formula: 0.5 < |f2 / EFL| < 1.5; and

[0011] The focal length f3 of the third lens and the focal length EFL of the large-aperture five-lens projection lens satisfy the conditional formula: 1.7 < |f3 / EFL| < 2; the focal length f4 of the fourth lens and the focal length EFL of the large-aperture five-lens projection lens satisfy the conditional formula: 1.3 < |f4 / EFL| < 1.8; the focal length f5 of the fifth lens and the focal length EFL of the large-aperture five-lens projection lens satisfy the conditional formula: 0.5 < |f5 / EFL| < 1.2.

[0012] In an alternative embodiment of the present utility model, the refractive index of the first lens is 1.7 to 1.9; and

[0013] The Abbe number of the first lens is 40 to 60.

[0014] In an alternative embodiment of the present utility model, the refractive index of the second lens is 1.5 to 1.7; and

[0015] The Abbe number of the second lens is 20 to 45.

[0016] In an alternative embodiment of the present utility model, the refractive index of the third lens is 1.7 to 1.9; and

[0017] The Abbe number of the third lens is 20 to 45.

[0018] In an alternative embodiment of the present utility model, the refractive index of the fourth lens is 1.8 to 2.0; and

[0019] The Abbe number of the fourth lens is 10 to 25.

[0020] In an alternative embodiment of the present utility model, the refractive index of the fifth lens is 1.7 to 1.9; and

[0021] The Abbe number of the fourth lens is 40 to 60.

[0022] In an alternative embodiment of the present utility model, the first lens, the second lens, the third lens, the fourth lens, and the fifth lens are all spherical glass lenses.

[0023] In an alternative embodiment of the present utility model, the back focal length BFL and the focal length EFL of the large-aperture five-element projection lens satisfy the conditional formula: 0.7 < BFL / EFL < 1.2.

[0024] In an alternative embodiment of the present utility model, the total optical length TTL and the focal length EF of the large-aperture five-element projection lens satisfy the conditional formula: 1.2 < TTL / EFL < 2.2.

[0025] The vehicle lamp of the present utility model is realized as follows:

[0026] A vehicle lamp, comprising: the large-aperture five-element projection lens described above.

[0027] By adopting the above technical solution, the present utility model has the following beneficial effects: The large-aperture five-element projection lens of the present utility model and the vehicle lamp using the same have a large aperture and a long back focus, meeting the spatial structure requirements of the DLP optical system, and at the same time having a very high overall light efficiency. In addition, for the five-element lens adopted, the global spherical glass structure realizes a high-quality imaging effect, does not affect its thermal stability, and at the same time has no special requirements for the temperature characteristics of the glass material, reducing the requirements for the temperature characteristics of the glass and reducing the material cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic structural diagram of the large-aperture five-element projection lens of Embodiment 1;

[0029] Figure 2 It is a schematic surface shape diagram of the large-aperture five-element projection lens of Embodiment 1;

[0030] Figure 3 It is a field curvature diagram of the large-aperture five-element projection lens of Embodiment 1;

[0031] Figure 4 It is a distortion diagram of the large-aperture five-element projection lens of Embodiment 1;

[0032] Figure 5 It is an axial chromatic aberration diagram of the large-aperture five-element projection lens of Embodiment 1;

[0033] Figure 6 It is an MTF diagram of the large-aperture five-element projection lens of Embodiment 1 at a corresponding temperature of 25°C;

[0034] Figure 7 It is an MTF diagram of the large-aperture five-element projection lens of Embodiment 1 at a corresponding temperature of 85°C;

[0035] Figure 8 It is an MTF diagram of the large-aperture five-element projection lens of Embodiment 1 at a corresponding temperature of 125°C.

[0036] In the figure: the first lens 1, the first diaphragm 2, the second lens 3, the third lens 4, the fourth lens 5, the second diaphragm 6, the fifth lens 7, and the DMD 8. Specific embodiments

[0037] In order to make the content of the present utility model easier to be clearly understood, the following further details the present utility model according to specific embodiments in conjunction with the accompanying drawings.

[0038] Embodiment 1:

[0039] Please refer to Figures 1 to 8 As shown, this embodiment provides a large-aperture five-piece projection lens, including: the first lens 1, the first diaphragm 2, the second lens 3, the third lens 4, the fourth lens 5, the second diaphragm 6, the fifth lens 7, and the DMD 8 arranged in sequence from the image side to the object side along the optical axis direction. Among them, the first lens 1 has a positive optical power; the second lens 3 has a negative optical power; the third lens 4 has a positive optical power, the fourth lens 5 has a negative optical power, and the fifth lens 7 has a positive optical power. The first lens 1, the second lens 3, the third lens 4, the fourth lens 5, and the fifth lens 7 are all spherical glass lenses.

[0040] The DMD 8 (Digital Micromirror Devices) is a microelectromechanical system (MEMS) with electronic input and optical output. It consists of many small aluminum reflective mirrors, and each mirror is called a pixel. Each mirror can deflect around the diagonal of each positive-direction small mirror (or called a pixel). The DMD 8 is based on semiconductor manufacturing technology and consists of a high-speed digital optical reflection switch array. By controlling the rotation of the micro-mirrors around the fixed (yoke) and the time-domain response (determining the reflection angle and residence time of the light), the imaging pattern and its characteristics are determined. The DMD 8 is a new type of fully digital flat display device that integrates a reflective micro-mirror array and a complementary metal oxide semiconductor static random access memory (SRAM) on the same chip using MEMS technology. The DMD 8 can perform full-surface photolithography according to the color range of the image, or perform block exposure according to the pixel size of the image.

[0041] Based on the above situation, it should be noted that the large-aperture five-piece projection lens uses a total of two diaphragms. The second diaphragm 6 is placed at the rear end near the object side, with an interval of at least 2 optical surfaces reserved from the first lens 1. The first diaphragm 2 is placed at the front end near the image side, with an interval of at least 2 optical surfaces reserved from the second diaphragm 6. This arrangement can make full use of the aberration correction ability of the aspherical surface and at the same time perform vignetting control on the off-axis field aberration.

[0042] In addition, it should be noted that:

[0043] The focal length f1 of the first lens 1 and the focal length EFL of the large-aperture five-element projection lens satisfy the conditional expression: 1 < |f1 / EFL| < 2; the refractive index of the first lens 1 is 1.7 to 1.9, and the Abbe number is 40 to 60.

[0044] The focal length f2 of the second lens 3 and the focal length EFL of the large-aperture five-element projection lens satisfy the conditional expression: 0.5 < |f2 / EFL| < 1.5; the refractive index of the second lens 3 is 1.5 to 1.7, and the Abbe number is 20 to 45.

[0045] The focal length f3 of the third lens 4 and the focal length EFL of the large-aperture five-element projection lens satisfy the conditional expression: 1.7 < |f3 / EFL| < 2; the refractive index of the third lens 4 is 1.7 to 1.9, and the Abbe number is 20 to 45.

[0046] The focal length f4 of the fourth lens 5 and the focal length EFL of the large-aperture five-element projection lens satisfy the conditional expression: 1.3 < |f4 / EFL| < 1.8. The refractive index of the fourth lens 5 is 1.8 to 2.0, and the Abbe number is 10 to 25.

[0047] The focal length f5 of the fifth lens 7 and the focal length EFL of the large-aperture five-element projection lens satisfy the conditional expression: 0.5 < |f5 / EFL| < 1.2. The refractive index of the fifth lens 7 is 1.7 to 1.9, and the Abbe number is 40 to 60.

[0048] Taking an example of a detailed optional case with reference to the attached drawings: At least the part corresponding to the optical axis of the surface of the first lens 1 facing the image side is a convex surface or a flat surface, and at least the part corresponding to the optical axis of the surface of the first lens 1 facing the object side is a convex surface. At least the part corresponding to the optical axis of the surface of the second lens 3 facing the image side is a concave surface, and at least the part corresponding to the optical axis of the surface of the second lens 3 facing the object side is a flat surface or a convex surface or a concave surface. At least the part corresponding to the optical axis of the surface of the third lens 4 facing the image side is a concave surface, and at least the part corresponding to the optical axis of the surface of the third lens 4 facing the object side is a convex surface. At least the part corresponding to the optical axis of the surface of the fourth lens 5 facing the image side is a convex surface, and at least the part corresponding to the optical axis of the surface of the fourth lens 5 facing the object side is a concave surface. The overall fourth lens 5 is a meniscus concave lens. At least the part corresponding to the optical axis of the surface of the fifth lens 7 facing the image side is a convex surface, and at least the part corresponding to the optical axis of the surface of the fourth lens 5 facing the object side is a flat surface or a convex surface.

[0049] For this, an example of the system parameters of a large-aperture five-element projection lens is as follows:

[0050] EFL 42.500 BFL 37.500 F / # 1.300 FOV ±8.1° EFL 42.500 BFL 37.500 F / # 1.300 FOV ±8.1°

[0051] Based on these system parameters, the field of view reaches ±8.1°, and BFL / EFL reaches 0.88.

[0052] The surface parameters are as follows:

[0053]

[0054] Refer to Figure 3 Figure 9 is the field curvature diagram of the large-aperture five-element projection lens corresponding to the above parameters. The abscissa in the figure represents the defocus amount, with the unit of mm, and the ordinate represents the image height, with the unit of mm.

[0055] Refer to Figure 4 Figure 14 is the distortion diagram of the large-aperture five-element projection lens corresponding to the above parameters. The abscissa in the figure represents the distortion value, with the unit of percentage, and the ordinate represents the image height, with the unit of mm; the full-field distortion can be achieved below 1%.

[0056] Refer to Figure 5 Figure 19 is the axial chromatic aberration diagram of the large-aperture five-element projection lens corresponding to the above parameters. The red-green and blue-green chromatic aberrations are both within 10um, and the lateral chromatic aberration is well controlled.

[0057] Refer to Figures 6 to 8 Figure 24 is the MTF diagram of the large-aperture five-element projection lens corresponding to the above parameters at temperatures of 25°C, 85°C, and 125°C. The full field of view reaches above 0.6, and the imaging quality is good.

[0058] Based on this, it should be noted that the large-aperture five-element projection lens of this embodiment can simultaneously meet the requirements of large aperture, large field of view, high image quality, and long back focal length, etc. The system F-number is between 1.2 and 1.35, and the imaging quality can reach the full field of view > ±7.8°, MTF > 0.6 @ 16.5 lp / mm (at a frequency of 16.5 lp / mm, the full-field MTF reaches above 0.5), and the imaging quality is good. The back focal length BFL and the focal length EFL of the large-aperture five-element projection lens of this embodiment satisfy the conditional formula: 0.7 < BFL / EFL < 1.2. The system length is also effectively shortened, and the overall optical length TTL and the focal length EF satisfy the conditional formula: 1.2 < TTL / EFL < 2.2.

[0059] In summary, the large-aperture five-element projection lens of this embodiment has a large aperture and a long back focal length, meets the spatial structure requirements of the DLP optical system, and has a very high overall light efficiency. In addition, for the five lenses used, the global spherical glass structure realizes high-quality imaging effects, does not affect its thermal stability, and has no special requirements for the temperature characteristics of the glass material, reducing the requirements for the temperature characteristics of the glass and reducing the material cost.

[0060] Embodiment 2:

[0061] Based on the large-aperture five-element projection lens of Embodiment 1, this embodiment provides a vehicle headlight, including: the large-aperture five-element projection lens of Embodiment 1.

[0062] In the above specific embodiments, the object, technical solution and beneficial effects of the present utility model have been further described in detail. It should be understood that the above are only specific embodiments of the present utility model and are not used to limit the present utility model. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.

[0063] In the description of the present utility model, it should be understood that the terms indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present utility model.

[0064] In the present utility model, unless otherwise clearly defined and limited, the terms "installed", "connected", "connected", "fixed", etc. should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0065] In the description of the present utility model, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present utility model is usually placed during use. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present utility model. In addition, the terms "first", "second", "third", etc. are only used for differential description and cannot be understood as indicating or implying relative importance.

[0066] In addition, the terms "horizontal", "vertical", "hanging", etc. do not mean that the components are required to be absolutely horizontal or hanging, but can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0067] In the present utility model, unless otherwise clearly stipulated and defined, the first feature being above or below the second feature may include the direct contact between the first and second features, or may include the contact between the first and second features not being direct but through additional features therebetween. Moreover, the first feature being above, on top of, and over the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the horizontal height of the first feature is higher than that of the second feature. The first feature being below, under, and beneath the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the horizontal height of the first feature is less than that of the second feature.

Claims

1. A large-aperture five-piece projection lens, characterized in that, Comprising: A first lens, a first aperture stop, a second lens, a third lens, a fourth lens, a second aperture stop, a fifth lens, and a DMD, which are sequentially arranged from the image side to the object side along the optical axis direction; Wherein The first lens has a positive optical power; the second lens has a negative optical power; the third lens has a positive optical power, the fourth lens has a negative optical power, and the fifth lens has a positive optical power; The focal length f1 of the first lens and the focal length EFL of the large-aperture five-piece projection lens satisfy the conditional formula: 1 < |f1 / EFL| < 2; the focal length f2 of the second lens and the focal length EFL of the large-aperture five-piece projection lens satisfy the conditional formula: 0.5 < |f2 / EFL| < 1.5; and The focal length f3 of the third lens and the focal length EFL of the large-aperture five-piece projection lens satisfy the conditional formula: 1.7 < |f3 / EFL| < 2; the focal length f4 of the fourth lens and the focal length EFL of the large-aperture five-piece projection lens satisfy the conditional formula: 1.3 < |f4 / EFL| < 1.8; the focal length f5 of the fifth lens and the focal length EFL of the large-aperture five-piece projection lens satisfy the conditional formula: 0.5 < |f5 / EFL| < 1.

2.

2. The large-aperture five-piece projection lens according to claim 1, wherein The refractive index of the first lens is 1.7 to 1.9; and The Abbe number of the first lens is 40 to 60.

3. The large-aperture five-piece projection lens according to claim 1, wherein The refractive index of the second lens is 1.5 to 1.7; and The Abbe number of the second lens is 20 to 45.

4. The large-aperture five-piece projection lens according to claim 1, wherein The refractive index of the third lens is 1.7 to 1.9; and The Abbe number of the third lens is 20 to 45.

5. The large-aperture five-piece projection lens according to claim 1, characterized in that The refractive index of the fourth lens is 1.8 to 2.0; and The Abbe number of the fourth lens is 10 to 25.

6. The large-aperture five-piece projection lens according to claim 1, wherein The refractive index of the fifth lens is 1.7 to 1.9; and The Abbe number of the fourth lens is 40 to 60.

7. The large-aperture five-piece projection lens according to claim 1, wherein, The first lens, the second lens, the third lens, the fourth lens, and the fifth lens are all spherical glass lenses.

8. The large-aperture five-piece projection lens according to claim 1, wherein The back focal length BFL of the large-aperture five-piece projection lens and the focal length EFL satisfy the conditional formula: 0.7 < BFL / EFL < 1.

2.

9. The large-aperture five-piece projection lens according to claim 1, wherein The overall optical length TTL of the large-aperture five-piece projection lens and the focal length EF satisfy the conditional formula: 1.2 < TTL / EFL < 2.

2.

10. A vehicle lamp, characterized in that, Comprising: The large-aperture five-piece projection lens according to any one of claims 1 to 9.

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