High-definition lens for vehicle-mounted electronic rearview mirror

Abstract

The utility model provides a high-definition lens for a vehicle-mounted electronic rearview mirror. A front lens group, an aperture diaphragm, a rear lens group, an optical filter and an imaging surface are sequentially arranged along an optical axis from an object space to an image space. The front lens group has negative focal power, and the rear lens group has positive focal power. The front lens group comprises a first lens with negative focal power, a second lens with negative focal power, a third lens with positive focal power and a fourth lens with positive focal power, and the rear lens group comprises a fifth lens with negative focal power, a sixth lens with positive focal power and a seventh lens with positive focal power. The fifth lens and the sixth lens form a bonding lens, chromatic aberration can be reduced or eliminated, and the imaging quality is improved. The second lens and the fifth lens are negative lenses, thereby facilitating correction of field curvature and improving imaging quality. The lens has the advantages of high resolution, small distortion and low cost, and can realize clear imaging in a temperature range of-40 DEG C to 105 DEG C.

Description

Technical Field

[0001] The utility model relates to the technical field of optical imaging equipment, in particular to a high-definition lens for a vehicle-mounted electronic rearview mirror. Background Art

[0002] In recent years, with the development of my country's national economy, people's travel range has become wider and wider, and the frequency of travel has become higher and higher. As an indispensable means of travel, cars have become people's main means of transportation. With the development of intelligent driving, as a part of collecting environmental information, electronic rearview mirrors are gradually replacing ordinary rearview mirrors. The automotive electronic rearview mirror is a system composed of a camera and a monitor. Compared with the traditional physical rearview mirror, the camera replaces the reflector, which can bring a wider field of view and a more flexible perspective to the driver, making it easier for the driver to judge the rear of the vehicle more quickly and accurately. Even in severe weather conditions such as heavy rain and snow, the electronic rearview mirror can provide better clarity. At the same time, the use of electronic rearview mirrors is conducive to reducing the wind resistance of the system and increasing the driving range. However, the traditional lens has a small field of view, obtains less environmental information, and has a high driving risk. At the same time, the aperture of the traditional lens is small, and the picture quality taken in a dark environment is very poor, which is not suitable for all-weather use. Utility Model Content

[0003] In view of the above problems, the purpose of the utility model is to provide a wide-angle high-definition lens for a vehicle-mounted electronic rearview mirror. The lens has the advantages of high resolution, large aperture and low cost. At the same time, it can achieve clear imaging in the temperature range of -40℃-105℃ and is suitable for complex vehicle driving environments.

[0004] In order to achieve the above-mentioned purpose, the technical solution adopted by the utility model is: a high-definition lens for a vehicle-mounted electronic rearview mirror, which is provided with a front lens group, an aperture stop, a rear lens group, a filter and an imaging surface in sequence along the optical axis from the object side to the image side; the front lens group has a negative optical focal length, and the rear lens group has a positive optical focal length; the front lens group includes a first lens with a negative optical focal length, a second lens with a negative optical focal length, a third lens with a positive optical focal length and a fourth lens with a positive optical focal length; the rear lens group includes a fifth lens with a negative optical focal length, a sixth lens with a positive optical focal length and a seventh lens with a positive optical focal length.

[0005] Furthermore,

[0006] The first lens is a meniscus lens;

[0007] The second lens is a biconcave lens;

[0008] The third lens is a plano-convex lens;

[0009] The fourth lens is a biconvex lens;

[0010] The fifth lens is a biconcave lens;

[0011] The sixth lens is a biconvex lens; the fifth lens and the sixth lens form a cemented lens with positive focal power;

[0012] The seventh lens is a biconvex lens.

[0013] The light refractive index of the first lens is Nd1, then Nd1>1.68;

[0014] The Abbe number of the first lens is Vd1, then Vd1>50;

[0015] The refractive index of the second lens is Nd2, then Nd2>1.57;

[0016] The Abbe number of the second lens is Vd2, then Vd2<45;

[0017] The refractive index of the third lens is Nd3, then Nd3>1.70;

[0018] The Abbe number of the third lens is Vd3, then Vd3>50;

[0019] The refractive index of the fourth lens is Nd4, then Nd4>1.90;

[0020] The Abbe number of the fourth lens is Vd4, then Vd4<35;

[0021] The refractive index of the fifth lens is Nd5, then Nd5>1.95;

[0022] The Abbe number of the fifth lens is Vd5, then Vd5<30;

[0023] The refractive index of the sixth lens is Nd6, then Nd6>1.50;

[0024] The Abbe number of the sixth lens is Vd6, then Vd6>65;

[0025] The refractive index of the seventh lens is Nd7, then Nd7>1.78;

[0026] The Abbe number of the seventh lens is Vd7, and Vd7>37.

[0027] The focal length of the high-definition lens is denoted as f, and the focal lengths of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens are denoted as f1, f2, f3, f4, f5, f6, f7 respectively, wherein f1, f2, f3, f4, f5, f6, f7 and f satisfy the following ratio:

[0028] -2≤f1 / f≤-1;

[0029] -1.8≤f2 / f≤0.8;

[0030] 1.1≤f3 / f≤2.1;

[0031] 1.1≤f4 / f≤2.1;

[0032] -1≤f5 / f≤-0.5;

[0033] 0.7≤f6 / f≤1.3;

[0034] 1.1≤f7 / f≤2.1.

[0035] The total optical length TTL and the optical back focus BFL of the high-definition lens satisfy the following relationship: 0.25<BFL / TTL≤0.34.

[0036] Compared with the prior art, the beneficial effects of the utility model are: 1) The utility model provides a high-definition and wide-angle automobile rearview mirror, which is suitable for automobile systems and the field of automatic driving, and can clearly distinguish long-distance details. Moreover, the lens has high resolution, small distortion, and low cost, and can achieve clear imaging within the temperature range of -40°C-105°C; 2) The cemented lens composed of the fifth lens and the sixth lens of the utility model can reduce or eliminate chromatic aberration, improve imaging quality, and the cemented lens improves lens transmittance and reduces assembly difficulty. The second lens and the fifth lens are negative lenses, which are beneficial to correct field curvature and improve imaging quality; 3) The second lens of the utility model is a double concave lens, and the first surface curvature is larger, which can better receive the light from the first lens and make the angle of light deflection on each surface smaller through reasonable optical focal length distribution, so the overall tolerance is better, and the main light angle CRA is small, only about 12 degrees, which can meet some chips requiring low CRA; the plane of the third lens plano-convex lens can reduce the assembly tolerance, which is beneficial to reduce the difficulty of assembly and reduce the image quality loss caused by the tolerance after assembly; 4) The utility model uses the above-mentioned seven spherical glass lenses to form a car rearview mirror, with a simple overall structure, small size, low cost, and small temperature drift, which meets the imaging requirements of high pixels and the needs of a large viewing angle, and can also correct image distortion to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a schematic diagram of the optical system structure of an embodiment of the utility model;

[0038] Figure 2 It is a schematic diagram of MTF at room temperature (20°C) of an embodiment of the utility model;

[0039] Figure 3 It is a schematic diagram of MTF at low temperature (-40°C) of an embodiment of the utility model;

[0040] Figure 4 It is a schematic diagram of MTF at high temperature (85°C) of an embodiment of the utility model;

[0041] Figure 5 A schematic diagram of distortion of an embodiment of the utility model;

[0042] Figure 6 Schematic diagram of relative illumination of an embodiment of the utility model. DETAILED DESCRIPTION

[0043] The following is a detailed description of the specific implementation of the embodiment of the present invention in conjunction with the accompanying drawings of the present invention. Figure 1 As shown, a high-definition lens for a vehicle-mounted electronic rearview mirror is provided with a front lens group, an aperture stop STOP, a rear lens group, a filter COVER and an imaging surface IMA in sequence along the optical axis from the object side to the image side; the front lens group has a negative optical power, and the rear lens group has a positive optical power; the front lens group includes a first lens L1 with a negative optical power, a second lens L2 with a negative optical power, a third lens L3 with a positive optical power and a fourth lens L4 with a positive optical power; the rear lens group includes a fifth lens L5 with a negative optical power, a sixth lens L6 with a positive optical power and a seventh lens L7 with a positive optical power. All of the above lenses are glass spherical lenses.

[0044] The first lens is a meniscus lens;

[0045] The second lens is a biconcave lens;

[0046] The third lens is a plano-convex lens;

[0047] The fourth lens is a biconvex lens;

[0048] The fifth lens is a biconcave lens;

[0049] The sixth lens is a biconvex lens; the fifth lens and the sixth lens form a cemented lens with positive focal power;

[0050] The seventh lens is a biconvex lens.

[0051] The light refractive index of the first lens is Nd1, then Nd1>1.68;

[0052] The Abbe number of the first lens is Vd1, then Vd1>50;

[0053] The refractive index of the second lens is Nd2, then Nd2>1.57;

[0054] The Abbe number of the second lens is Vd2, then Vd2<45;

[0055] The refractive index of the third lens is Nd3, then Nd3>1.70;

[0056] The Abbe number of the third lens is Vd3, then Vd3>50;

[0057] The refractive index of the fourth lens is Nd4, then Nd4>1.90;

[0058] The Abbe number of the fourth lens is Vd4, then Vd4<35;

[0059] The refractive index of the fifth lens is Nd5, then Nd5>1.95;

[0060] The Abbe number of the fifth lens is Vd5, then Vd5<30;

[0061] The refractive index of the sixth lens is Nd6, then Nd6>1.50;

[0062] The Abbe number of the sixth lens is Vd6, then Vd6>65;

[0063] The refractive index of the seventh lens is Nd7, then Nd7>1.78;

[0064] The Abbe number of the seventh lens is Vd7, and Vd7>37.

[0065] The focal length of the high-definition lens is denoted as f, and the focal lengths of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens are denoted as f1, f2, f3, f4, f5, f6, f7 respectively, wherein f1, f2, f3, f4, f5, f6, f7 and f satisfy the following ratio:

[0066] -2≤f1 / f≤-1;

[0067] -1.8≤f2 / f≤0.8;

[0068] 1.1≤f3 / f≤2.1;

[0069] 1.1≤f4 / f≤2.1;

[0070] -1≤f5 / f≤-0.5;

[0071] 0.7≤f6 / f≤1.3;

[0072] 1.1≤f7 / f≤2.1.

[0073] The total optical length TTL and the optical back focus BFL of the high-definition lens satisfy the following relationship: 0.25<BFL / TTL≤0.34.

[0074] The preferred values ​​of the relevant parameters of each lens are shown in Table 2:

[0075]

[0076] Figure 1 This is a schematic diagram of the optical system structure of an embodiment of the utility model. The overall length of the system is less than 22 mm. The entire structure is small and compact, with good anti-vibration effect, and is very suitable for use in various vehicle-mounted camera systems.

[0077] Figure 2 This is a normal temperature (20°C) MTF (Modulation Transfer Function) curve of the embodiment of the utility model. The horizontal axis in the figure represents the spatial frequency, unit: line pair / millimeter (lp / mm), and the vertical axis represents the MTF value. It can be seen from the figure that the MTF curve of this embodiment has a relatively high concentration, indicating that the imaging consistency of the entire image plane of the technical solution of this embodiment is excellent, and a high-definition image can be obtained on the entire image plane. At 166lp / mm, the overall MTF value is as high as about 40%.

[0078] Figure 3 This is a low temperature (-40°C) MTF (Modulation Transfer Function) curve of the embodiment of the utility model. The horizontal axis in the figure represents the spatial frequency, in units of line pairs / mm (lp / mm), and the vertical axis represents the MTF value. It can be seen from the figure that under the low temperature condition of -40°C, the MTF curves of all viewing fields of this embodiment can be maintained at about 30%, which is not significantly reduced compared with the normal temperature of 20°C.

[0079] Figure 4 This is a high temperature (85°C) MTF (Modulation Transfer Function) curve of an embodiment of the utility model. The horizontal axis in the figure represents the spatial frequency, in units of line pairs / mm (lp / mm), and the vertical axis represents the MTF value. It can be seen from the figure that under the high temperature condition of 85°C, all the MTF curves of the field of view of this embodiment can be maintained above 30% without obvious decline.

[0080] Figure 5 This is a distortion diagram of the present invention, where the horizontal axis represents the distortion percentage and the vertical axis represents the field of view. Figure 5 It can be seen that the distortion in the entire image plane is about 16%.

[0081] Figure 6 This is a relative illumination diagram of the present invention, in which the horizontal axis represents the field of view and the vertical axis represents the relative illumination value. Figure 6 It can be seen that the relative illumination of the edge field of view is as high as 75% compared to the central field of view.

[0082] The above-mentioned embodiments are only a part of the embodiments of the utility model, and the concept and scope of the utility model are not limited to the details of the above-mentioned exemplary embodiments. Therefore, under the premise of not departing from the design concept of the utility model, various modifications and improvements made by other technicians in the field according to the technical solution of the utility model should fall within the protection scope of the utility model, and the contents of the utility model to be protected are all recorded in the claims.

Claims

1. A high-definition lens for a vehicle-mounted electronic rearview mirror, characterized in that: A front lens group, an aperture stop, a rear lens group, a filter and an imaging surface are arranged in sequence along the optical axis from the object side to the image side; the front lens group has negative optical power, and the rear lens group has positive optical power; the front lens group includes a first lens with negative optical power, a second lens with negative optical power, a third lens with positive optical power and a fourth lens with positive optical power; the rear lens group includes a fifth lens with negative optical power, a sixth lens with positive optical power and a seventh lens with positive optical power.

2. The high-definition lens for a vehicle-mounted electronic rearview mirror according to claim 1, characterized in that: The first lens is a meniscus lens; The second lens is a biconcave lens; The third lens is a plano-convex lens; The fourth lens is a biconvex lens; The fifth lens is a biconcave lens; The sixth lens is a biconvex lens; the fifth lens and the sixth lens form a cemented lens with positive focal power; The seventh lens is a biconvex lens.

3. The high-definition lens for a vehicle-mounted electronic rearview mirror according to claim 2, characterized in that: The light refractive index of the first lens is Nd1, then Nd1>1.68; The Abbe number of the first lens is Vd1, then Vd1>50; The refractive index of the second lens is Nd2, then Nd2>1.57; The Abbe number of the second lens is Vd2, then Vd2<45; The refractive index of the third lens is Nd3, then Nd3>1.70; The Abbe number of the third lens is Vd3, then Vd3>50; The refractive index of the fourth lens is Nd4, then Nd4>1.90; The Abbe number of the fourth lens is Vd4, then Vd4<35; The refractive index of the fifth lens is Nd5, then Nd5>1.95; The Abbe number of the fifth lens is Vd5, then Vd5<30; The refractive index of the sixth lens is Nd6, then Nd6>1.50; The Abbe number of the sixth lens is Vd6, then Vd6>65; The refractive index of the seventh lens is Nd7, then Nd7>1.78; The Abbe number of the seventh lens is Vd7, and Vd7>37.

4. The high-definition lens for a vehicle-mounted electronic rearview mirror according to claim 3, characterized in that: The focal length of the high-definition lens is denoted as f, and the focal lengths of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens and the seventh lens are denoted as f1, f2, f3, f4, f5, f6, f7 respectively, wherein f1, f2, f3, f4, f5, f6, f7 and f satisfy the following ratio: -2≤f1 / f≤-1; -1.8≤f2 / f≤0.8; 1.1≤f3 / f≤2.1; 1.1≤f4 / f≤2.1; -1≤f5 / f≤-0.5; 0.7≤f6 / f≤1.3; 1.1≤f7 / f≤2.

1.

5. The high-definition lens for a vehicle-mounted electronic rearview mirror according to claim 4, characterized in that: The total optical length TTL and the optical back focus BFL of the high-definition lens satisfy the following relationship: 0.25<BFL / TTL≤0.34.

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