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

Abstract

The utility model discloses a large-aperture four-piece projection lens and a vehicle lamp using the same. The large-aperture four-piece projection lens comprises a first lens, a first diaphragm, a second lens, a third lens, a second diaphragm, a fourth lens and a DMD which are sequentially arranged from an image side to an object side along an optical axis direction, wherein the first lens is an aspherical mirror; the second lens has positive focal power; the third lens has negative focal power, and the fourth lens has positive focal power; the focal length f1 of the first lens and the focal length EFL of the large-aperture four-piece projection lens meet the conditional expression: 0 < EFL / f1 < 0.1; the focal length f2 of the second lens and the focal length EFL of the large-aperture four-piece projection lens meet the conditional expression: 2 < f2 / EFL < 3; the focal length f3 of the third lens and the focal length EFL of the large-aperture four-piece projection lens meet the conditional expression: 1.5 < f3 / EFL < 2; and the focal length f4 of the fourth lens and the focal length EFL of the large-aperture four-piece projection lens meet the conditional expression: 0.5 < f4 / EFL < 1.2.

Description

Technical Field

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

[0002] With the development of topics such as intelligent sensing and safe driving in the automotive field, the role of headlights, as the "glasses" for night driving, in driving safety has become increasingly important. Their functions have gradually evolved from single lighting to adaptive high beams and now more intelligent and pixelated projection lights.

[0003] Currently, pixelated and intelligent projection headlights are primarily based on digital light processing (DLP) projection technology and high-pixel LEDs. DLP technology has been used in projectors for many years. Projection headlights can achieve high-definition projections of millions of pixels and require a lighting system, a light modulator (DMD), and a projection lens. Due to system structural limitations, the projection lens requires a very long back focus. To improve system light efficiency, the projection lens also requires a large aperture. These requirements pose greater challenges to projection lens design. Existing four-element projection lenses employ a combination of aspherical and spherical lenses. The aspherical lenses typically use low-melting-point glass to reduce overall lens weight, but the image quality is poor, with the transfer function (MTF) only reaching above 0.4.

[0004] Therefore, for the four-piece projection lens used in the DLP optical system, how to balance the requirements of large aperture and high-quality imaging effects while reducing production costs and product weight is a technical difficulty that needs to be overcome. Utility Model Content

[0005] The first object of the present invention is to provide a large-aperture four-lens projection lens to solve the technical problem of reducing weight and improving imaging effect.

[0006] The second object of the present invention is to provide a vehicle lamp to solve the technical problem of reducing the weight and improving the imaging effect of the lens used therein.

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

[0008] A large aperture four-lens projection lens, comprising: a first lens, a first aperture, a second lens, a third lens, a second aperture, a fourth lens and a DMD arranged in sequence from the image side to the object side along the optical axis; wherein

[0009] The first lens is an aspherical lens; the second lens has positive optical power; the third lens has negative optical power; and the fourth lens has positive optical power;

[0010] The focal length f1 of the first lens and the focal length EFL of the large-aperture four-piece projection lens satisfy the conditional formula: 0<|EFL / f1|<0.1; the focal length f2 of the second lens and the focal length EFL of the large-aperture four-piece projection lens satisfy the conditional formula: 2<|f2 / EFL|<3; and

[0011] The focal length f3 of the third lens and the focal length EFL of the large-aperture four-piece projection lens satisfy the condition: 1.5<|f3 / EFL|<2; the focal length f4 of the fourth lens and the focal length EFL of the large-aperture four-piece projection lens satisfy the condition: 0.5<|f4 / EFL|<1.2.

[0012] In an optional implementation of the present invention, the refractive index of the first lens is 1.53 to 1.65; and

[0013] The Abbe number of the first lens is 25-35.

[0014] In an optional implementation of the present invention, the refractive index of the second lens is 1.7 to 1.9; and

[0015] The Abbe number of the second lens is 40-60.

[0016] In an optional implementation of the present invention, the refractive index of the third lens is 1.8 to 2.0; and

[0017] The Abbe number of the third lens is 17-25.

[0018] In an optional implementation of the present invention, the refractive index of the fourth lens is 1.7 to 1.9; and

[0019] The Abbe number of the fourth lens is 40-60.

[0020] In an optional implementation of the present invention, the first lens is a plastic lens; and

[0021] The second lens, the third lens and the fourth lens are all spherical glass lenses.

[0022] In an optional implementation of the present invention, the back focal length BFL and the focal length EFL of the large-aperture four-element projection lens satisfy the condition: 0.7<BFL / EFL<1.2.

[0023] In an optional implementation of the present invention, the total optical length TTL and the focal length EF of the large-aperture four-element projection lens satisfy the condition: 1.2<TTL / EFL<2.2.

[0024] In an optional embodiment of the present invention, at least a portion of a surface of the first lens facing the image side corresponding to the optical axis is a convex surface, and at least a portion of a surface of the first lens facing the object side corresponding to the optical axis is a concave surface;

[0025] The image-side surface of the second lens is concave at least in a portion corresponding to the optical axis, and the object-side surface of the second lens is convex at least in a portion corresponding to the optical axis.

[0026] The image-side surface of the third lens is convex in at least a portion corresponding to the optical axis, and the object-side surface of the third lens is concave in at least a portion corresponding to the optical axis.

[0027] At least a portion of a surface of the fourth lens facing the image side corresponding to the optical axis is a convex surface, and at least a portion of a surface of the fourth lens facing the object side corresponding to the optical axis is a concave surface.

[0028] The headlight of the present utility model is realized as follows:

[0029] A vehicle lamp comprises the large-aperture four-piece projection lens.

[0030] By adopting the above-mentioned technical solution, the present invention achieves the following beneficial effects: The large-aperture four-element projection lens and the vehicle lamp using it have a large aperture and long back focus, meeting the spatial structure requirements of DLP optical systems while also providing high overall light efficiency. Furthermore, the four-element lens structure, comprising one aspherical plastic lens and three spherical glass lenses, achieves high-quality imaging while reducing the weight and cost of the projection lens. The outermost surface of the lens is made of PC optical resin, which meets high-temperature requirements and can be coated, improving overall light efficiency and increasing the freedom of design. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic structural diagram of a large-aperture four-lens projection lens according to Example 1;

[0032] Figure 2 Schematic diagram of the surface shape of the large-aperture four-element projection lens of Example 1;

[0033] Figure 3 This is a field curvature diagram of the large-aperture four-element projection lens of Example 1;

[0034] Figure 4 This is a distortion diagram of the large-aperture four-element projection lens of Example 1;

[0035] Figure 5 This is the MTF diagram of the large-aperture four-element projection lens of Example 1;

[0036] Figure 6axial chromatic aberration diagram of the large-aperture four-element projection lens of Example 1.

[0037] In the figure: first lens 1, first aperture 2, second lens 3, third lens 4, second aperture 5, fourth lens 6, DMD 7. DETAILED DESCRIPTION

[0038] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments in conjunction with the accompanying drawings.

[0039] Example 1:

[0040] See also Figures 1 to 6 As shown, this embodiment provides a large-aperture four-element projection lens, comprising: a first lens 1, a first aperture 2, a second lens 3, a third lens 4, a second aperture 5, a fourth lens 6, and a DMD 7, arranged in sequence along the optical axis from the image side to the object side. The second lens 3 has positive refractive power; the third lens 4 has negative refractive power; and the fourth lens 6 has positive refractive power.

[0041] The DMD7 digital micromirror device (DMD) is a microelectromechanical system (MEMS) with electronic input and optical output. It consists of numerous small aluminum reflective mirrors, each of which is called a pixel. Each mirror is capable of deflecting diagonally around the positive direction of each small mirror (or pixel). Based on semiconductor manufacturing technology, the DMD7 consists of a high-speed digital optical reflective switch array. The image pattern and its characteristics are determined by controlling the rotation of the micromirrors around a fixed (yoke) and the time domain response (which determines the reflection angle and dwell time of light). The DMD7 is a new, fully digital flat-panel display device that utilizes MEMS technology to integrate the reflective micromirror array and complementary metal oxide semiconductor static random access memory (SRAM) on the same chip. The DMD7 can perform full-surface photolithography based on the image's color range or perform block exposure based on the image's pixel size.

[0042] The first lens 1 is an aspherical lens; the second lens 3, third lens 4, and fourth lens 6 are all spherical lenses. In terms of material, the first lens 1 is made of plastic, while the second lens 3, third lens 4, and fourth lens 6 are all made of glass. The combination of plastic and glass lenses achieves high-quality imaging. The first lens 1 is an aspherical plastic lens made of PC optical resin, which can be coated and various shapes can be achieved through injection molding, and it can also meet high-temperature operating requirements.

[0043] Based on the above situation, it should be noted that the large-aperture four-element projection lens uses a total of two apertures. The second aperture 5 is placed at the rear end close to the object side, and is separated from the first lens 1 by at least two optical surfaces. The first aperture 2 is placed at the front end close to the image side, and is separated from the second aperture 5 by at least two optical surfaces. This arrangement can fully utilize the aberration correction capability of the aspheric surface, while controlling vignetting of off-axis field aberrations.

[0044] Furthermore, for the first lens 1, the optical surfaces on both sides thereof are aspherical surfaces, and the expression of the aspherical surface shape is:

[0045]

[0046] The parameters are as follows:

[0047] Surf k c A2 A4 A6 A8 A10 1 -14.517 0.028 0.000E+00 3.750E-05 -8.741E-08 5.637E-12 -1.466E-13 2 -0.695 0.027 0.000E+00 1.306E-05 8.651E-08 -6.306E-10 7.910E-13

[0048] In addition, it should be noted that:

[0049] The focal length f1 of the first lens 1 and the focal length EFL of the large-aperture four-lens projection lens satisfy the condition: 0<|EFL / f1|<0.1; the refractive index of the first lens 1 is 1.53-1.65, and the Abbe number is 25-35.

[0050] The focal length f2 of the second lens 3 and the focal length EFL of the large-aperture four-lens projection lens satisfy the condition: 2<|f2 / EFL|<3; the refractive index of the second lens 3 is 1.7-1.9, and the Abbe number is 40-60.

[0051] The focal length f3 of the third lens 4 and the focal length EFL of the large-aperture four-lens projection lens satisfy the condition: 1.5<|f3 / EFL|<2; the refractive index of the third lens 4 is 1.8-2.0, and the Abbe number is 17-25.

[0052] The focal length f4 of the fourth lens 6 and the focal length EFL of the large-aperture four-lens projection lens satisfy the condition: 0.5 < |f4 / EFL| < 1.2. The refractive index of the fourth lens 6 is 1.7-1.9, and the Abbe number is 40-60.

[0053] With reference to the accompanying drawings, a detailed optional situation is given as an example: at least the portion of the image-facing side of the first lens 1 corresponding to the optical axis is convex, and at least the portion of the object-facing side of the first lens 1 corresponding to the optical axis is concave. At least the portion of the image-facing side of the second lens 3 corresponding to the optical axis is concave, and at least the portion of the object-facing side of the second lens 3 corresponding to the optical axis is convex. At least the portion of the image-facing side of the third lens 4 corresponding to the optical axis is convex, and at least the portion of the object-facing side of the third lens 4 corresponding to the optical axis is concave. At least the portion of the image-facing side of the fourth lens 6 corresponding to the optical axis is convex, and at least the portion of the object-facing side of the fourth lens 6 corresponding to the optical axis is concave.

[0054] For this purpose, the system parameters of a large-aperture four-element projection lens are as follows:

[0055] EFL 42.500 BFL 37.500 F / # 1.300 FOV ±8.1°

[0056] Based on the system parameters, the field of view reaches ±8.1° and the BFL / EFL reaches 0.88.

[0057] The surface parameters are as follows:

[0058]

[0059] Reference Figure 3 The field curvature diagram of the large-aperture four-element projection lens corresponding to the above parameters is shown in FIG. 8 , where the horizontal axis represents the defocus amount in mm, and the vertical axis represents the image height in mm.

[0060] Reference Figure 4 This is the distortion diagram of the large-aperture four-element projection lens corresponding to the above parameters. The horizontal axis in the figure represents the distortion value in percentage, and the vertical axis represents the image height in mm. The distortion can be achieved at about 1% in the full field of view.

[0061] Reference Figure 5 The MTF diagram of the large-aperture four-element projection lens corresponding to the above parameters shows that the full field of view reaches above 0.5, and the imaging quality is good.

[0062] Reference Figure 6 This is the axial chromatic aberration diagram of the large-aperture four-element projection lens corresponding to the above parameters. The red-green and blue-green color differences are all below 2μm, and the vertical axis chromatic aberration is well controlled.

[0063] Based on this, it should be noted that the large-aperture four-element projection lens of this embodiment can simultaneously achieve the requirements of large aperture, wide field of view, high image quality, and long back focus. The system F-number is between 1.2 and 1.35, and the imaging quality can achieve >±7.8° across the entire field of view and MTF >0.5@16.5lp / mm (MTF for the entire field of view is above 0.5 at a frequency of 16.5lp / mm). The image quality is excellent. The back focus length BFL and focal length EFL of the large-aperture four-element projection lens of this embodiment meet the condition: 0.7 < BFL / EFL < 1.2. The system length is also effectively shortened, with the total optical length TTL and focal length EF meeting the condition: 1.2 < TTL / EFL < 2.2.

[0064] In summary, the large-aperture, four-element projection lens of this embodiment features a large aperture and long back focus, meeting the spatial requirements of DLP optical systems while also delivering high overall light efficiency. Furthermore, the four-element lens structure, comprising one aspherical plastic lens and three spherical glass lenses, achieves high-quality imaging while reducing the weight and cost of the projection lens.

[0065] Example 2:

[0066] Based on the large-aperture four-piece projection lens of Example 1, this embodiment provides a vehicle lamp, including: the large-aperture four-piece projection lens of Example 1.

[0067] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

[0068] In the description of the present invention, it should be understood that the terms indicating orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it cannot be understood as a limitation on the present invention.

[0069] In this utility model, unless otherwise specified or limited, the terms "installed," "connected," "connect," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection; direct connection, indirect connection through an intermediate medium, internal communication between two components, or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in this utility model based on specific circumstances.

[0070] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer" and the like, indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships in which the utility model product is typically placed when in use. These terms are intended solely to facilitate the description of this utility model and to simplify the description, and are not intended to indicate or imply that the device or component referred to must have a specific orientation, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first," "second," and "third," etc., are used solely to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0071] Furthermore, terms such as "horizontal," "vertical," and "overhanging" do not necessarily imply that a component must be absolutely horizontal or overhanging, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but rather that it can be slightly tilted.

[0072] In the present invention, unless otherwise expressly specified or limited, a first feature being above or below a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being above, above, and above the second feature includes the first feature being directly above and obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being below, below, and below the second feature includes the first feature being directly below and obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

Claims

1. A large-aperture four-element projection lens, characterized in that: include: A first lens, a first aperture, a second lens, a third lens, a second aperture, a fourth lens, and a DMD are sequentially arranged along the optical axis from the image side to the object side; in The first lens is an aspherical lens; The second lens has positive optical power; the third lens has negative optical power; and the fourth lens has positive optical power; The focal length f1 of the first lens and the focal length EFL of the large-aperture four-piece projection lens satisfy the condition: 0<|EFL / f1|<0.1; the focal length f2 of the second lens and the focal length EFL of the large-aperture four-piece projection lens satisfy the condition: 2<|f2 / EFL|<3; as well as The focal length f3 of the third lens and the focal length EFL of the large-aperture four-piece projection lens satisfy the condition: 1.5<|f3 / EFL|<2; the focal length f4 of the fourth lens and the focal length EFL of the large-aperture four-piece projection lens satisfy the condition: 0.5<|f4 / EFL|<1.

2.

2. The large-aperture four-element projection lens according to claim 1, wherein: The refractive index of the first lens is 1.53 to 1.65; and The Abbe number of the first lens is 25-35.

3. The large-aperture four-element projection lens according to claim 1, wherein: The refractive index of the second lens is 1.7 to 1.9; and The Abbe number of the second lens is 40-60.

4. The large-aperture four-element projection lens according to claim 1, wherein: The refractive index of the third lens is 1.8 to 2.0; and The Abbe number of the third lens is 17-25.

5. The large-aperture four-element projection lens according to claim 1, wherein: The refractive index of the fourth lens is 1.7 to 1.9; and The Abbe number of the fourth lens is 40-60.

6. The large-aperture four-element projection lens according to claim 1, wherein: The first lens is a plastic lens; and The second lens, the third lens and the fourth lens are all spherical glass lenses.

7. The large-aperture four-element projection lens according to claim 1, wherein: The back focal length BFL and the focal length EFL of the large-aperture four-element projection lens satisfy the condition: 0.7<BFL / EFL<1.

2.

8. The large-aperture four-element projection lens according to claim 1, wherein: The total optical length TTL and the focal length EF of the large-aperture four-piece projection lens satisfy the condition: 1.2<TTL / EFL<2.

2.

9. The large-aperture four-element projection lens according to claim 1, wherein: The first lens has a convex surface on its image side and at least a portion thereof corresponding to the optical axis, and a concave surface on its object side and at least a portion thereof corresponding to the optical axis; The image-side surface of the second lens is concave at least in a portion corresponding to the optical axis, and the object-side surface of the second lens is convex at least in a portion corresponding to the optical axis. The image-side surface of the third lens is convex in at least a portion corresponding to the optical axis, and the object-side surface of the third lens is concave in at least a portion corresponding to the optical axis. At least a portion of a surface of the fourth lens facing the image side corresponding to the optical axis is a convex surface, and at least a portion of a surface of the fourth lens facing the object side corresponding to the optical axis is a concave surface.

10. A vehicle lamp, characterized in that: include: A large-aperture four-element projection lens as claimed in any one of claims 1 to 9.

Images