Ultra-wide cat eye door mirror
By designing an optical system for an ultra-wide-angle peephole, the problem of traditional peepholes being incompatible with different door thicknesses was solved. This enabled the peephole to be applicable to doors of different thicknesses and expand the observation range, thereby reducing production costs and improving observation clarity.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- TP-LINK
- Filing Date
- 2025-05-16
- Publication Date
- 2026-05-29
Smart Images
Figure CN224303927U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of cat's eye lens technology, and more specifically, it relates to an ultra-wide-angle cat's eye door mirror. Background Technology
[0002] A peephole (also known as a door peephole) is an optical observation device widely installed in security doors, apartment doors, and other similar scenarios. It allows users to observe the outside environment from inside the door, providing both security and privacy protection.
[0003] Traditional peepholes have relatively fixed dimensions, providing a clear view only within a short observation range. Beyond this effective viewing distance, image quality deteriorates, with reduced clarity and a decreased field of view. However, door thicknesses vary significantly, and smart doorbells are becoming increasingly mainstream. Traditional peepholes, with their short length and limited compatibility, struggle to meet current peephole demands.
[0004] Therefore, manufacturers are forced to develop multiple specifications of products for different door thicknesses, which increases production costs, complicates inventory management, and requires users to replace the door mirrors when replacing the door, resulting in a waste of resources. Utility Model Content
[0005] The purpose of this utility model embodiment is to provide an ultra-wide-angle peephole door view to solve the technical problem of incompatibility with different door thicknesses in the prior art.
[0006] To achieve the above objectives, the technical solution adopted by this utility model is: to provide an ultra-wide-angle peephole camera, comprising a first lens, a second lens, a third lens, and a fourth lens arranged sequentially from the object side to the image side.
[0007] The first lens is a meniscus lens with negative optical power and convex to the object side.
[0008] The second lens is a negative power biconcave lens.
[0009] The third lens is a negative power biconcave lens.
[0010] The fourth lens is a positive power biconvex lens.
[0011] Optionally, the first lens, the second lens, the third lens, and the fourth lens are all plastic lenses, the first lens, the second lens, and the third lens form an objective lens group, and the fourth lens forms an eyepiece group.
[0012] Optionally, the refractive index of the first lens is Nd1, 1.52≦Nd1≦1.64; the refractive index of the second lens is Nd2, 1.49≦Nd2≦1.55; the refractive index of the third lens is Nd3, 1.49≦Nd3≦1.55; and the refractive index of the fourth lens is Nd4, 1.52≦Nd4≦1.64.
[0013] Optionally, the Abbe number of the first lens is Vd1, 20.38 ≤ Vd1 ≤ 55.99; the Abbe number of the second lens is Vd2, 55.71 ≤ Vd2 ≤ 57.45; the Abbe number of the third lens is Vd3, 55.71 ≤ Vd3 ≤ 57.45; and the Abbe number of the fourth lens is Vd4, 20.38 ≤ Vd4 ≤ 55.99.
[0014] Optionally, the first lens, the second lens, the third lens, and the fourth lens are all glass lenses, the first lens and the second lens form an objective lens group, and the third lens and the fourth lens form an eyepiece group.
[0015] Optionally, the refractive index of the first lens is Nd1, 1.83≦Nd1≦1.92; the refractive index of the second lens is Nd2, 1.74≦Nd2≦1.85; the refractive index of the third lens is Nd3, 1.49≦Nd3≦1.59; and the refractive index of the fourth lens is Nd4, 1.72≦Nd4≦1.81.
[0016] Optionally, the Abbe number of the first lens is Vd1, 20.78 ≤ Vd1 ≤ 42.73; the Abbe number of the second lens is Vd2, 23.76 ≤ Vd2 ≤ 49.6; the Abbe number of the third lens is Vd3, 56.04 ≤ Vd3 ≤ 81.61; and the Abbe number of the fourth lens is Vd4, 25.44 ≤ Vd4 ≤ 54.65.
[0017] Optionally, the focal length of the objective lens group is -6mm≦f o ≦-3mm, the focal length of the eyepiece group is 60mm≦f e ≤70mm, where -18≦f e / f o ≦-13.
[0018] Optionally, the length L of the objective lens group o The total length (TTL) of the peephole mirror satisfies the relationship 0.05 ≤ L. o / TTL≦0.18.
[0019] Optionally, the distance between the surface of the first lens facing the object and the image plane is the length of the peephole. When the length of the peephole is between 90mm and 160mm, the field of view of the ultra-wide-angle peephole is greater than 170 degrees.
[0020] The beneficial effects of the ultra-wide-angle peephole door view provided by this utility model are as follows: Compared with the prior art, the ultra-wide-angle peephole door view of this utility model includes a first lens, a second lens, a third lens and a fourth lens. The first lens is a meniscus lens with negative optical power convex to the object side. The second and third lenses are both negative optical power biconcave lenses. The fourth lens is a positive optical power biconvex lens. When the length of the door view is between 90mm and 160mm, the field of view of the door view is greater than 170 degrees. That is, when the length of the door view is between 90mm and 160mm, it can meet the requirements of the visual optical system. In this way, the door view can be used for door bodies of different thicknesses and has strong compatibility. Attached Figure Description
[0021] To more clearly illustrate the technical solutions in the embodiments of this utility model, 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.
[0022] Figure 1 A schematic diagram of the structure of the first ultra-wide-angle peephole mirror provided in this embodiment of the utility model;
[0023] Figure 2 A schematic diagram of the structure of the second type of ultra-wide-angle peephole mirror provided in this embodiment of the present invention;
[0024] Figure 3 Schematic diagram of the structure of the third ultra-wide-angle peephole mirror provided in this embodiment of the utility model Figure 1 ;
[0025] Figure 4 Schematic diagram of the structure of the third ultra-wide-angle peephole mirror provided in this embodiment of the utility model Figure 2 ;
[0026] Figure 5 for Figure 1 Standard dot matrix diagram of the ultra-wide-angle peephole camera;
[0027] Figure 6 for Figure 1 MTF plot of the ultra-wide-angle peephole peephole when the peephole length is 95mm;
[0028] Figure 7 for Figure 1MTF chart of an ultra-wide-angle peephole peephole with a peephole length of 135mm;
[0029] Figure 8 for Figure 1 MTF plot of the ultra-wide-angle peephole peephole when the peephole length is 145mm;
[0030] Figure 9 for Figure 1 MTF plot of the ultra-wide-angle cat's eye door mirror at a temperature of -30℃;
[0031] Figure 10 for Figure 1 MTF plot of the ultra-wide-angle cat's eye door mirror at a temperature of 70℃;
[0032] Figure 11 for Figure 1 Distortion image of an ultra-wide-angle cat's-eye peephole;
[0033] Figure 12 for Figure 2 Standard dot matrix diagram of the ultra-wide-angle peephole camera;
[0034] Figure 13 for Figure 2 MTF plot of the ultra-wide-angle peephole peephole when the peephole length is 95mm;
[0035] Figure 14 for Figure 2 MTF plot of an ultra-wide-angle peephole peephole when the peephole length is 100mm;
[0036] Figure 15 for Figure 2 MTF chart of an ultra-wide-angle peephole peephole with a peephole length of 135mm;
[0037] Figure 16 for Figure 2 MTF plot of the ultra-wide-angle peephole peephole when the peephole length is 145mm;
[0038] Figure 17 for Figure 2 MTF chart of an ultra-wide-angle peephole peephole with a peephole length of 155mm;
[0039] Figure 18 for Figure 2 MTF plot of the ultra-wide-angle cat's eye door mirror at a temperature of -30℃;
[0040] Figure 19 for Figure 2 MTF plot of the ultra-wide-angle cat's eye door mirror at a temperature of 70℃;
[0041] Figure 20 for Figure 2Distortion image of an ultra-wide-angle cat's-eye peephole;
[0042] Figure 21 for Figure 3 Standard dot matrix diagram of the ultra-wide-angle peephole camera;
[0043] Figure 22 for Figure 3 MTF plot of an ultra-wide-angle peephole peephole when the peephole length is 100mm;
[0044] Figure 23 for Figure 3 MTF chart of an ultra-wide-angle peephole peephole with a peephole length of 135mm;
[0045] Figure 24 for Figure 3 MTF plot of the ultra-wide-angle peephole peephole when the peephole length is 145mm;
[0046] Figure 25 for Figure 3 MTF plot of the ultra-wide-angle cat's eye door mirror at a temperature of -40℃;
[0047] Figure 26 for Figure 3 MTF plot of the ultra-wide-angle cat's eye door mirror at a temperature of 80℃;
[0048] Figure 27 for Figure 3 The distortion image of the ultra-wide-angle cat's-eye peephole.
[0049] The following are the labeling elements in the figure:
[0050] 10-First lens; 20-Second lens; 30-Third lens; 40-Fourth lens; 50-Door body; 60-Image plane; 70-Doorbell. Detailed Implementation
[0051] To make the technical problems, technical solutions, and beneficial effects of this utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the present utility model.
[0052] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.
[0053] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.
[0054] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.
[0055] The ultra-wide-angle peephole mirror provided in the embodiments of this utility model will now be described.
[0056] Please refer to the following: Figures 1 to 4 The ultra-wide-angle peephole includes a first lens 10, a second lens 20, a third lens 30, and a fourth lens 40 arranged sequentially from the object side to the image side.
[0057] The first lens 10 is a meniscus lens with negative optical power convex to the object side.
[0058] The second lens 20 is a negative power biconcave lens.
[0059] The third lens 30 is a negative power biconcave lens.
[0060] The fourth lens 40 is a positive power biconvex lens.
[0061] The object side refers to the object that needs to be imaged through the ultra-wide-angle peephole, while the image side refers to the observer's side. Optical power is a measure of a lens's ability to converge or diverge light rays. Lenses with positive optical power (generally convex lenses) can converge light rays, while lenses with negative optical power (generally concave lenses) can diverge light rays.
[0062] From the object side to the image side, the two surfaces of the lens are referred to as the first surface and the second surface, respectively. The first surface of the first lens 10 is convex, and the second surface of the first lens 10 is concave. Both the first and second surfaces of the second lens 20 are concave. Both the first and second surfaces of the third lens 30 are concave. Both the first and second surfaces of the fourth lens 40 are convex. Here, "convex" and "concave" are relative to each lens itself.
[0063] The ultra-wide-angle peephole peephole in the above embodiment includes a first lens 10, a second lens 20, a third lens 30, and a fourth lens 40. The first lens 10 is a meniscus lens with negative optical power convex towards the object side. The second lens 20 and the third lens 30 are both negative optical power biconcave lenses, and the fourth lens 40 is a positive optical power biconvex lens. This ensures that when the length of the peephole is between 90mm and 160mm, the field of view of the peephole is greater than 170 degrees. In other words, the requirements of the visual optical system can be met when the length of the peephole is between 90mm and 160mm. Thus, the peephole can be used with door bodies 50 of different thicknesses and door assemblies (including door body 50 and doorbell 70) of different thicknesses, exhibiting strong compatibility. The length of the peephole is the distance between the object-facing surface of the first lens 10 and the image plane 60.
[0064] Please refer to some embodiments of this utility model. Figure 1 and Figure 2 The first lens 10, the second lens 20, the third lens 30, and the fourth lens 40 are all made of plastic. The first lens 10, the second lens 20, and the third lens 30 form the objective lens group, and the fourth lens 40 forms the eyepiece group. The objective lens group, consisting of three objective lenses, deflects large-angle light rays to the eyepiece to obtain a wide field of view. The fact that the first lens 10, the second lens 20, the third lens 30, and the fourth lens 40 are all made of plastic, which has a lower manufacturing cost, reduces the cost of the peephole.
[0065] Optionally, the first lens 10, the second lens 20, the third lens 30, and the fourth lens 40 are all plastic spherical lenses.
[0066] In other embodiments, the first lens 10, the second lens 20, the third lens 30, and the fourth lens 40 are all plastic lenses. Alternatively, the first lens 10 and the second lens 20 can form an objective lens group, and the third lens 30 and the fourth lens 40 can form an eyepiece group.
[0067] Please refer to some embodiments of this utility model. Figure 1 and Figure 2 When the first lens 10, the second lens 20, the third lens 30, and the fourth lens 40 are all plastic spherical mirrors, the refractive index of the first lens 10 is Nd1, 1.52≦Nd1≦1.64; the refractive index of the second lens 20 is Nd2, 1.49≦Nd2≦1.55; the refractive index of the third lens 30 is Nd3, 1.49≦Nd3≦1.55; and the refractive index of the fourth lens 40 is Nd4, 1.52≦Nd4≦1.64.
[0068] In gantry lens systems, the refractive indices of the objective and eyepiece directly affect optical performance and structural design. The selection of their refractive indices requires a trade-off between aberration control, structural compactness, and cost, and optimization can be achieved through compound lenses or aspherical designs.
[0069] Please refer to some embodiments of this utility model. Figure 1 and Figure 2 The Abbe number of the first lens 10 is Vd1, 20.38 ≤ Vd1 ≤ 55.99; the Abbe number of the second lens 20 is Vd2, 55.71 ≤ Vd2 ≤ 57.45; the Abbe number of the third lens 30 is Vd3, 55.71 ≤ Vd3 ≤ 57.45; and the Abbe number of the fourth lens 40 is Vd4, 20.38 ≤ Vd4 ≤ 55.99.
[0070] The Abbe number (V value) reflects the dispersion characteristics of a material and affects the chromatic aberration performance of a lens. High Abbe number materials have low dispersion, used to reduce chromatic aberration in optical systems. Low Abbe number materials have high dispersion, corrected for chromatic aberration using complementary lens groups. In some embodiments of this invention, materials with extreme dispersion are not used, reducing costs and avoiding high structural tolerance sensitivity.
[0071] Please refer to some embodiments of this utility model. Figure 1 The ultra-wide-angle cat's eye peephole includes an objective lens group (first lens 10, second lens 20 and third lens 30) and an eyepiece group (fourth lens 40). The diameter of the eyepiece is less than 9mm. When the length of the peephole is adjusted between 95mm and 145mm, the field of view of the peephole is not lost and the field of view is not less than 178 degrees.
[0072] The reason for considering a small aperture is that the peephole openings on doors vary in size. In order to accommodate the smallest peephole diameter of 10mm on common doors, the aperture of some lenses is limited to less than 9mm to allow for the thickness of structural components such as the lens barrel.
[0073] During installation, the eyepiece is placed inside the door opening, so the eyepiece aperture must be <9mm. The objective lens can be placed on the outdoor unit of the smart doorbell or on the outside of the door, so the aperture can be appropriately enlarged. However, the third lens (taking all-plastic as an example), which is close to the door opening, also needs to ensure that the effective surface aperture through which light passes is <9mm, otherwise the light will be blocked by the lens barrel.
[0074] Optionally, the parameters of the ultra-wide-angle peephole are shown in Table 1. Wherein, S1 is the first surface of the first lens 10, S2 is the second surface of the first lens 10, S3 is the first surface of the second lens 20, S4 is the second surface of the second lens 20, S5 is the first surface of the third lens 30, S6 is the second surface of the third lens 30, S7 is the first surface of the fourth lens 40, and S8 is the second surface of the fourth lens 40.
[0075] Table 1
[0076]
[0077]
[0078] In Table 1, the aperture 60 coincides with the image plane 60, which is the position of the human eye pupil.
[0079] Figure 5 This is the standard dot plot of this embodiment. The dot plot of the afocal system is used to describe the parallelism of light rays. The smaller the RMS radius of the dot plot, the closer the light rays are to parallel emission, which is beneficial to achieving near imaging effect with different total lengths of portal lenses. Figures 6 to 8 The MTF plots for door mirror lengths of 95mm, 135mm, and 145mm in this embodiment are shown. As can be seen from the plots, the values of 15lp / degree and 7.5lp / degree are high enough to meet the requirements for image clarity. Figure 9 This is the MTF plot when the peephole temperature is -30℃. Figure 10 The image shows the MTF chart of the peephole at a temperature of 70℃. The peephole is partially exposed outdoors, and the environment is relatively complex. The peephole maintains stable clarity under extreme conditions. Figure 11 The distortion diagram for this embodiment shows a smooth distortion curve. At a 50-degree field of view (half-angle, vertical axis), the distortion is within 40% (horizontal axis), so the distortion of the main subject of the image is acceptable.
[0080] Please refer to some embodiments of this utility model. Figure 2 The ultra-wide-angle peephole camera includes an objective lens group (first lens 10, second lens 20 and third lens 30) and an eyepiece group (fourth lens 40). The diameter of the eyepiece is less than 9mm. When the length of the peephole is adjusted between 95mm and 155mm, the field of view of the peephole is not lost and the field of view is not less than 180 degrees.
[0081] Optionally, the parameters of the ultra-wide-angle peephole are shown in Table 2. Wherein, S1 is the first surface of the first lens 10, S2 is the second surface of the first lens 10, S3 is the first surface of the second lens 20, S4 is the second surface of the second lens 20, S5 is the first surface of the third lens 30, S6 is the second surface of the third lens 30, S7 is the first surface of the fourth lens 40, and S8 is the second surface of the fourth lens 40.
[0082] Table 2
[0083]
[0084]
[0085] In Table 2, the aperture 60 coincides with the image plane, which is the position of the human eye pupil.
[0086] Figure 12 This is the standard dot plot of this embodiment. The dot plot of the afocal system is used to describe the parallelism of light rays. The smaller the RMS radius of the dot plot, the closer the light rays are to parallel emission, which is beneficial to achieving near imaging effect with different total lengths of portal lenses. Figures 13 to 17The MTF plots for door mirror lengths of 95mm, 100mm, 135mm, 145mm, and 155mm in this embodiment are shown. As can be seen from the plots, the values of 15lp / degree and 7.5lp / degree are high enough to meet the requirements for image clarity. Figure 18 This is the MTF plot when the peephole temperature is -30℃. Figure 19 The image shows the MTF chart of the peephole at a temperature of 70℃. The peephole is partially exposed outdoors, and the environment is relatively complex. The peephole maintains stable clarity under extreme conditions. Figure 20 The distortion diagram for this embodiment shows a smooth distortion curve. At a 50-degree field of view (half-angle, vertical axis), the distortion is within 40% (horizontal axis), so the distortion of the main subject of the image is acceptable.
[0087] The fourth lens 40 of the ultra-wide-angle peephole described in this embodiment adopts a replaceable design (corresponding to the two sets of data S6, S7, and S8 in Table 2). Limited by the maximum compatible total length, the fixed design cannot achieve the best optical effect at a small total length. After replacing the fourth lens 40 with the replaceable design, the peephole has a larger viewing area and higher resolution at a small total length, and can obtain higher clarity at different total lengths.
[0088] Please refer to some embodiments of this utility model. Figure 3 and Figure 4 The first lens 10, the second lens 20, the third lens 30 and the fourth lens 40 are all glass lenses. The first lens 10 and the second lens 20 form the objective lens group, and the third lens 30 and the fourth lens 40 form the eyepiece group.
[0089] Optionally, the first lens 10, the second lens 20, the third lens 30 and the fourth lens 40 are all glass spherical lenses.
[0090] Please refer to some embodiments of this utility model. Figure 3 and Figure 4 The refractive index of the first lens 10 is Nd1, 1.83≦Nd1≦1.92; the refractive index of the second lens 20 is Nd2, 1.74≦Nd2≦1.85; the refractive index of the third lens 30 is Nd3, 1.49≦Nd3≦1.59; and the refractive index of the fourth lens 40 is Nd4, 1.72≦Nd4≦1.81.
[0091] In gantry lens systems, the refractive indices of the objective and eyepiece directly affect optical performance and structural design. The selection of their refractive indices requires a trade-off between aberration control, structural compactness, and cost, and optimization can be achieved through compound lenses or aspherical designs.
[0092] Please refer to some embodiments of this utility model. Figure 3 and Figure 4The Abbe number of the first lens 10 is Vd1, 20.78 ≤ Vd1 ≤ 42.73; the Abbe number of the second lens 20 is Vd2, 23.76 ≤ Vd2 ≤ 49.6; the Abbe number of the third lens 30 is Vd3, 56.04 ≤ Vd3 ≤ 81.61; and the Abbe number of the fourth lens 40 is Vd4, 25.44 ≤ Vd4 ≤ 54.65.
[0093] The Abbe number (V value) reflects the dispersive properties of a material and affects the chromatic aberration performance of a lens. High Abbe number materials have low dispersion and are used to reduce chromatic aberration in optical systems. Low Abbe number materials have high dispersion and are corrected for chromatic aberration using complementary lens groups. In some embodiments of this utility model, materials with extreme dispersion are not used to reduce costs and avoid high structural tolerance sensitivity.
[0094] Please refer to some embodiments of this utility model. Figure 3 and Figure 4 The ultra-wide-angle peephole camera includes an objective lens group (first lens 10 and second lens 20) and an eyepiece group (third lens 30 and fourth lens 40). The diameter of the eyepiece is less than 9mm. When the length of the peephole is adjusted between 100mm and 145mm, the field of view of the peephole is not lost and the field of view is not less than 180 degrees.
[0095] Optionally, the parameters of the ultra-wide-angle peephole are shown in Table 3. Wherein, S1 is the first surface of the first lens 10, S2 is the second surface of the first lens 10, S3 is the first surface of the second lens 20, S4 is the second surface of the second lens 20, S5 is the first surface of the third lens 30, S6 is the second surface of the third lens 30, S7 is the first surface of the fourth lens 40, and S8 is the second surface of the fourth lens 40.
[0096] Table 3
[0097]
[0098] In Table 3, the aperture 60 coincides with the image plane, which is the position of the human eye pupil.
[0099] Figure 21 This is the standard dot plot of this embodiment. The dot plot of the afocal system is used to describe the parallelism of light rays. The smaller the RMS radius of the dot plot, the closer the light rays are to parallel emission, which is beneficial to achieving near imaging effect with different total lengths of portal lenses. Figures 22 to 24 The MTF plots for door mirror lengths of 100mm, 135mm, and 145mm in this embodiment are shown. As can be seen from the plots, the values of 15lp / degree and 7.5lp / degree are high enough to meet the image clarity requirements. Figure 25 This is the MTF plot when the gantry temperature is -40℃. Figure 26The image shows the MTF chart of the peephole at a temperature of 80℃. The peephole is partially exposed outdoors, and the environment is relatively complex. The peephole maintains stable clarity under extreme conditions. Figure 27 The distortion diagram for this embodiment shows a smooth distortion curve. At a 50-degree field of view (half-angle, vertical axis), the distortion is within 40% (horizontal axis), so the distortion of the main subject of the image is acceptable.
[0100] Please refer to some embodiments of this utility model. Figures 1 to 4 The focal length of the objective lens group is -6mm ≤ f. o ≤-3mm, focal length of eyepiece group 60mm ≤f e ≤70mm, where -18≦f e / f o ≦-13.
[0101] The focal length of the objective lens and the lens directly affects the field of view, magnification, and depth of field of a gantry camera. Limited by the overall length of the gantry camera, an excessively large absolute value of the objective lens's focal length will result in a narrow field of view (capturing only a small area of the scene). An excessively small absolute value of the objective lens's focal length will overly compress the field of view, reduce the resolution of the image seen by the human eye, decrease the size of the viewing area, exacerbate distortion, and make the subject of the image more severely distorted. Furthermore, an excessively short focal length requires a lens with higher curvature, which may introduce spherical aberration and increase manufacturing costs. Designing the objective lens's focal length between -6mm and -3mm can balance spatial constraints, image quality requirements, and field of view.
[0102] In some embodiments, the focal length of the objective lens is -6mm, -5mm, -4mm, -3mm, etc.
[0103] In some embodiments, the focal length of the eyepiece is 60mm, 63mm, 65mm, 67mm, etc.
[0104] In some embodiments of this invention, within a 50-degree field of view, the modulation transfer function (MTF) at 15 lp / degree is greater than 0.6; within a 50-90 degree field of view, the MTF at 7.5 lp / degree is greater than 0.7. The MTF at 15 lp / degree corresponding to the main subject of the image (within a 50-degree field of view) is greater than 0.6, indicating a high MTF that meets the resolution requirements. Due to inherent large distortion at the edge of the field of view, objects are severely compressed; therefore, using a 7.5 lp / degree MTF for evaluation shows a smoother distortion change.
[0105] In some embodiments of this invention, the objective lens group length L o The total length (TTL) of the gantry mirror satisfies the relationship 0.05 ≤ L. o / TTL≦0.18. The objective lens group length refers to the distance from the first surface of the first objective lens to the second surface of the last objective lens. When all lenses are plastic, the objective lens group length is the distance from the first surface of the first lens to the second surface of the third lens. When all lenses are glass, the objective lens group length is the distance from the first surface of the first lens to the second surface of the second lens.
[0106] In some embodiments of this invention, when the peephole length is between 90mm and 160mm, the field of view of the ultra-wide-angle peephole peephole is greater than 170 degrees. Adjusting the peephole length between 90mm and 160mm meets the requirements of the visual optical system and offers strong compatibility. Furthermore, the larger field of view means a wider viewing area. This allows users to cover a larger area without having to get close to the peephole, potentially reducing blind spots. For example, a traditional peephole may only show the area directly in front, while the peephole in this embodiment can see a wider angle, close to 180 degrees, allowing visibility even when someone is standing next to the door, improving security. Additionally, the large field of view makes it easier for users to observe multiple visitors or larger packages, such as delivery personnel carrying large boxes, providing a more comprehensive view of the area outside the door and preventing missed details. At the same time, for families with children or pets, the large field of view makes it easier to monitor activities outside the door, preventing accidents.
[0107] In some embodiments, the field of view (FOV) of the ultra-wide-angle peephole is 175 degrees, 178 degrees, 180 degrees, etc.
[0108] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.
Claims
1. An ultra-wide-angle peephole camera, characterized in that, It includes a first lens, a second lens, a third lens, and a fourth lens arranged sequentially from the object side to the image side. The first lens is a meniscus lens with negative optical power and convex to the object side. The second lens is a negative power biconcave lens. The third lens is a negative power biconcave lens. The fourth lens is a positive power biconvex lens.
2. The ultra-wide-angle peephole door view as described in claim 1, characterized in that, The first lens, the second lens, the third lens, and the fourth lens are all plastic lenses. The first lens, the second lens, and the third lens form an objective lens group, and the fourth lens forms an eyepiece group.
3. The ultra-wide-angle peephole door view as described in claim 2, characterized in that, The first lens has a refractive index of Nd1, 1.52 ≤ Nd1 ≤ 1.64; the second lens has a refractive index of Nd2, 1.49 ≤ Nd2 ≤ 1.55; the third lens has a refractive index of Nd3, 1.49 ≤ Nd3 ≤ 1.55; and the fourth lens has a refractive index of Nd4, 1.52 ≤ Nd4 ≤ 1.
64.
4. The ultra-wide-angle peephole door view as described in claim 2, characterized in that, The Abbe number of the first lens is Vd1, 20.38 ≤ Vd1 ≤ 55.99; the Abbe number of the second lens is Vd2, 55.71 ≤ Vd2 ≤ 57.45; the Abbe number of the third lens is Vd3, 55.71 ≤ Vd3 ≤ 57.45; and the Abbe number of the fourth lens is Vd4, 20.38 ≤ Vd4 ≤ 55.
99.
5. The ultra-wide-angle peephole door view as described in claim 1, characterized in that, The first lens, the second lens, the third lens, and the fourth lens are all glass lenses. The first lens and the second lens form an objective lens group, and the third lens and the fourth lens form an eyepiece group.
6. The ultra-wide-angle peephole door view as described in claim 5, characterized in that, The first lens has a refractive index of Nd1, 1.83 ≤ Nd1 ≤ 1.92; the second lens has a refractive index of Nd2, 1.74 ≤ Nd2 ≤ 1.85; the third lens has a refractive index of Nd3, 1.49 ≤ Nd3 ≤ 1.59; and the fourth lens has a refractive index of Nd4, 1.72 ≤ Nd4 ≤ 1.
81.
7. The ultra-wide-angle peephole door view as described in claim 5, characterized in that, The Abbe number of the first lens is Vd1, 20.78 ≤ Vd1 ≤ 42.73; the Abbe number of the second lens is Vd2, 23.76 ≤ Vd2 ≤ 49.6; the Abbe number of the third lens is Vd3, 56.04 ≤ Vd3 ≤ 81.61; and the Abbe number of the fourth lens is Vd4, 25.44 ≤ Vd4 ≤ 54.
65.
8. The ultra-wide-angle peephole door view as described in any one of claims 2-7, characterized in that, The focal length of the objective lens group is -6mm≦f o ≦-3mm, the focal length of the eyepiece group is 60mm≦f e ≤70mm, where -18≤f e / f o ≤-13.
9. The ultra-wide-angle peephole door view as described in any one of claims 2-7, characterized in that, The length L of the objective lens group o The total length (TTL) of the peephole mirror satisfies the relationship 0.05 ≤ L. o / TTL≦0.
18.
10. The ultra-wide-angle peephole door view as described in any one of claims 1-7, characterized in that, The distance between the object-facing surface of the first lens and the image plane is the length of the peephole. When the length of the peephole is between 90mm and 160mm, the field of view of the ultra-wide-angle peephole is greater than 170 degrees.