Fixed-focus lens and smart door lock

Abstract

The present invention discloses a fixed-focus lens and an intelligent door lock. The fixed-focus lens has an object side and an image side that are oppositely arranged along the optical axis direction. The fixed-focus lens includes a first lens with a negative optical power, a second lens with a positive or negative optical power, a diaphragm, a third lens with a positive optical power, a fourth lens with a negative optical power, and a fifth lens with a positive optical power, which are sequentially arranged from the object side to the image side. The fixed-focus lens satisfies the following conditions: 0.97 < |f1 / f| < 1.82, 7.2 < |f2 / f| < 13.4, 1.1 < |f3 / f| < 2.1, 1.1 < |f4 / f| < 2.1, 1.0 < |f5 / f| < 2.0. The aperture value F of the fixed-focus lens satisfies 1.8 ≤ F ≤ 2.2. The fixed-focus lens can also achieve clear imaging in low light, and by reasonably setting the focal length ratio, the lens does not defocus under high and low temperature environmental conditions, and the working performance is more stable. The field of view angle is greater than 170°, with a wide field of view, so as to provide a low-cost, small-size, large-aperture, high-definition fixed-focus lens that supports day and night confocal imaging.

Description

Technical Field

[0001] The present invention relates to the field of optical technologies, and particularly to a fixed-focus lens and an intelligent door lock. Background Art

[0002] In recent years, fixed-focus lenses have played an increasingly important role in the smart home industry and are widely used in household appliances such as refrigerators and door locks. With the increasing development of intelligent door locks, the requirements for the lenses of intelligent door locks are getting higher and higher, mainly reflected in the higher pursuit of resolution, volume, and aperture.

[0003] Currently, the lenses of intelligent door locks are costly, have low clarity, and do not support day-night confocal imaging. Summary of the Invention

[0004] The main object of the present invention is to provide a fixed-focus lens and an intelligent door lock, aiming to provide a high-definition fixed-focus lens with low cost, small volume, large aperture, and support for day-night confocal imaging.

[0005] To achieve the above object, a fixed-focus lens proposed by the present invention has an object side and an image side disposed oppositely along the optical axis direction. The fixed-focus lens includes a first lens with a negative optical power, a second lens with a positive or negative optical power, a diaphragm, a third lens with a positive optical power, a fourth lens with a negative optical power, and a fifth lens with a positive optical power, which are sequentially arranged from the object side to the image side. The fixed-focus lens satisfies the following conditions:

[0006] 0.97 < |f1 / f| < 1.82, and 7.2 < |f2 / f| < 13.4, and 1.1 < |f3 / f| < 2.1, and 1.1 < |f4 / f| < 2.1, and 1.0 < |f5 / f| < 2.0;

[0007] Wherein, f is the total focal length of the fixed-focus lens, f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, and f5 is the focal length of the fifth lens.

[0008] Optionally, the object side surface of the first lens is convex, and the image side surface of the first lens is concave;

[0009] The object side surface of the second lens is concave, and the image side surface of the second lens is convex;

[0010] The object side surface of the third lens is convex, and the image side surface of the third lens is convex;

[0011] The object side surface of the fourth lens is concave, and the image side surface of the fourth lens is concave;

[0012] The object side surface of the fifth lens is convex, and the image side surface of the fifth lens is convex.

[0013] Optionally, the first lens and the third lens are glass spherical lenses;

[0014] The second lens, the fourth lens and the fifth lens are plastic aspherical lenses.

[0015] Optionally, the diaphragm and the fixed-focus lens satisfy the following condition: 0.5 < SD / TTL < 0.94;

[0016] Wherein, SD is the distance between the diaphragm and the imaging plane of the fixed-focus lens on the optical axis, and TTL is the total optical length of the fixed-focus lens.

[0017] Optionally, the total optical length of the fixed-focus lens satisfies 9 < TTL < 17.

[0018] Optionally, the fixed-focus lens satisfies the following condition: 3.7 < TTL / f < 7; wherein, TTL is the total optical length of the fixed-focus lens.

[0019] Optionally, the dispersion coefficient vd4 of the fourth lens satisfies: 20 < vd4 < 40.

[0020] Optionally, the dispersion coefficient vd5 of the fifth lens satisfies: 40 < vd5 < 70.

[0021] Optionally, the fixed-focus lens further includes a protective glass and a photosensitive chip in sequence from the object side to the image side, and the protective glass and the photosensitive chip are disposed on one side of the fifth lens close to the image side.

[0022] The present invention also provides an intelligent door lock, and the intelligent door lock includes the above-mentioned fixed-focus lens.

[0023] In the technical solution provided by the present invention, a first lens with a negative optical power, a second lens with a positive optical power, a third lens with a positive optical power, a fourth lens with a negative optical power, and a fifth lens with a positive optical power are sequentially arranged from the object side to the image side. The fixed-focus lens satisfies the following conditions: 0.97 < |f1 / f| < 1.82, 7.2 < |f2 / f| < 13.4, 1.1 < |f3 / f| < 2.1, 1.1 < |f4 / f| < 2.1, and 1.0 < |f5 / f| < 2.0. By setting the first lens with a negative optical power, it plays a role in collecting light for a large-field optical system and corrects axial chromatic aberration at the same time. By setting the second lens with a positive or negative optical power, the volume of the lens can be reduced and off-axis astigmatism can be corrected. The aperture is used to adjust the light flux according to the actual situation, which can improve the imaging quality. The third lens can correct the system chromatic aberration and ensure the imaging performance of the optical system at high and low temperatures. By setting the fourth lens and the fifth lens, the system chromatic aberration, spherical aberration, and field curvature can be corrected. Through the reasonable setting of the optical powers and shapes of the five lenses, the fixed-focus lens can well control the light path, make the structure more compact while introducing more light, so that the aperture value F of the fixed-focus lens satisfies 1.8 ≤ F ≤ 2.2. The fixed-focus lens can also clearly image in low light, and by reasonably setting the focal ratio, the lens does not defocus under high and low temperature environmental conditions, and the working performance is more stable. The field of view angle is greater than 170°, with a wide field of view, so as to provide a high-definition fixed-focus lens with low cost, small volume, large aperture, and supporting day and night confocal imaging. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on the structures shown in these drawings.

[0025] Figure 1 It is a schematic structural diagram of the fixed-focus lens provided by the present invention;

[0026] Figure 2 For Figure 1 the spherical aberration curve schematic diagram of the fixed-focus lens in

[0027] Figure 3 For Figure 1 the ray fan schematic diagram of the fixed-focus lens in

[0028] Figure 4 For Figure 1 the field distortion / field curvature schematic diagram of the fixed-focus lens in

[0029] Description of the attached reference numerals:

[0030] Reference numeral Name Reference numeral Name 1 First lens 5 Fifth lens 2 Second lens 6 Diaphragm 3 Third lens 7 Protective glass 4 Fourth lens 8 Photosensitive chip

[0031] The realization, functional features and advantages of the purpose of the present invention will be further described in conjunction with the embodiments with reference to the accompanying drawings. Specific embodiments

[0032] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0033] It should be noted that if there are directional indications (such as up, down, left, right, front, back...) involved in the embodiments of the present invention, then the directional indications are only used to explain the relative positional relationship and movement conditions between components in a certain specific posture (as shown in the accompanying drawings). If this specific posture changes, then the directional indications will also change accordingly.

[0034] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, then the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, the meaning of "and / or" appearing throughout the text includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, or solution B, or a solution where A and B are satisfied simultaneously. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement it. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0035] In recent years, fixed-focus lenses have played an increasingly important role in the smart home industry and are widely used in home appliances such as refrigerators and door locks. With the increasing development of smart door locks, the requirements for smart door lock lenses are getting higher and higher, mainly reflected in the higher pursuit of resolution, volume, and aperture. Currently, the cost of smart door lock lenses is relatively high, the clarity is not high, and they do not support day and night confocal.

[0036] To solve the above problems, the present invention provides a fixed-focus lens, Figures 1 to 4 This is a specific embodiment of the fixed-focus lens provided by the present invention.

[0037] Please refer to Figure 1, the fixed-focus lens has an object side and an image side that are oppositely arranged along the optical axis direction. The fixed-focus lens includes a first lens 1 with a negative optical power, a second lens 2 with a positive or negative optical power, a diaphragm 6, a third lens 3 with a positive optical power, a fourth lens 4 with a negative optical power, and a fifth lens 5 with a positive optical power, which are arranged in sequence from the object side to the image side. The fixed-focus lens satisfies the following conditions: 0.97 < |f1 / f| < 1.82, and 7.2 < |f2 / f| < 13.4, and 1.1 < |f3 / f| < 2.1, and 1.1 < |f4 / f| < 2.1, and 1.0 < |f5 / f| < 2.0; where f is the total focal length of the fixed-focus lens, f1 is the focal length of the first lens 1, f2 is the focal length of the second lens 2, f3 is the focal length of the third lens 3, f4 is the focal length of the fourth lens 4, and f5 is the focal length of the fifth lens 5.

[0038] In the technical solution provided by the present invention, a first lens 1 with a negative optical power, a second lens 2 with a positive optical power, a third lens 3 with a positive optical power, a fourth lens 4 with a negative optical power, and a fifth lens 5 with a positive optical power are arranged in sequence from the object side to the image side. The fixed-focus lens satisfies the following conditions: 1.2 < |f1 / f| < 2.0, and 3 < |f2 / f| < 10, and 1.2 < |f3 / f| < 2.5, and 0.8 < |f4 / f| < 2.0, and 0.8 < |f5 / f| < 2.0. By setting the first lens 1 with a negative optical power, it plays a role in collecting light for a large-field-of-view optical system and corrects axial chromatic aberration at the same time. By setting the second lens 2 with a positive or negative optical power, the volume of the lens can be reduced and off-axis astigmatism can be corrected. The diaphragm 6 is used to adjust the light flux according to the actual situation, which can improve the imaging quality. The third lens 3 can correct the system chromatic aberration and ensure the imaging performance of the optical system at high and low temperatures. By setting the fourth lens 4 and the fifth lens 5, the system chromatic aberration, spherical aberration, and field curvature can be corrected. Through the reasonable setting of the optical powers and shapes of the five lenses, the fixed-focus lens can well control the light path, introduce more light while making the structure more compact, so that the aperture value F of the fixed-focus lens satisfies 1.8 ≤ F ≤ 2.2. The fixed-focus lens can also clearly image in low light, and by reasonably setting the focal length ratio, the lens does not defocus under high and low temperature environmental conditions, and the working performance is more stable. The field of view angle is greater than 170°, and the field of view is wide, so as to provide a low-cost, small-volume, large-aperture, fixed-focus lens that supports day and night confocal high definition.

[0039] Specifically, in one embodiment, the object-side surface of the first lens 1 is convex, and the image-side surface of the first lens 1 is concave; the object-side surface of the second lens 2 is concave, and the image-side surface of the second lens 2 is convex; the object-side surface of the third lens 3 is convex, and the image-side surface of the third lens 3 is convex; the object-side surface of the fourth lens 4 is concave, and the image-side surface of the fourth lens 4 is concave; the object-side surface of the fifth lens 5 is convex, and the image-side surface of the fifth lens 5 is convex.

[0040] More specifically, in a specific embodiment, the first lens 1 and the third lens 3 are glass spherical lenses; the second lens 2, the fourth lens 4 and the fifth lens 5 are plastic aspherical lenses. Since resin lenses have strong impact resistance, light weight and low cost, plastic aspherical lenses can be used to effectively control costs. If all plastic aspherical lenses are used, the plastic material is easily affected by the ambient temperature, which will make the chemical properties of the fixed-focus lens relatively unstable, and its refractive index is weaker than that of the full glass lens, resulting in a poorer picture restoration than the full glass lens. In order to ensure the stability of the fixed-focus lens under temperature changes, in this embodiment, the first lens 1 and the third lens 3 are glass spherical lenses. Glass lenses are not easily affected by thermal expansion and contraction and have a focus shift phenomenon. Therefore, glass lenses can well resist the problem of thermal deformation of the fixed-focus lens in high and low temperature environments, and maintain the high precision of the lens for a long time. It can eliminate the aberration that occurs during imaging as much as possible, thereby improving the imaging quality of the fixed-focus lens and reducing the influence of temperature on the optical performance of the lens. The fixed-focus lens is made of a glass-plastic hybrid material, which not only saves costs and has strong impact resistance, but also ensures the stability of the system and its applicability to high and low temperatures.

[0041] Specifically, in this embodiment, the aperture 6 and the fixed-focus lens satisfy the following condition: 0.5<SD / TTL<0.94; wherein SD is the distance between the aperture 6 and the imaging surface of the fixed-focus lens on the optical axis, and TTL is the total optical length of the fixed-focus lens.

[0042] Specifically, in this embodiment, the total optical length of the fixed-focus lens is 9<TTL<17. In this way, while introducing more light, the fixed-focus lens is made compact and has a small volume, which is in line with the miniaturization characteristics of the smart door lock.

[0043] More specifically, the fixed-focus lens meets the following conditions: 3.7 <TTL / f<7;其中,TTL为所述定焦镜头的光学总长。

[0044] Specifically, in this embodiment, the dispersion coefficient vd4 of the fourth lens 4 satisfies: 20<vd4<40.

[0045] Specifically, in this embodiment, the dispersion coefficient vd5 of the fifth lens 5 satisfies: 40 < vd5 < 70. The larger the dispersion coefficient (Abbe number), the less obvious the dispersion, and the better the imaging quality of the lens. In this embodiment, the dispersion coefficients of the lenses are controlled at relatively high values, making the dispersion of the fixed-focus lens less obvious and the imaging quality of the lens better.

[0046] Further, in this embodiment, the fixed-focus lens further includes a protective glass 7 and an image sensor chip 8 in sequence from the object side to the image side, and the protective glass 7 and the image sensor chip 8 are disposed on a side of the fifth lens 5 close to the image side. The protective glass 7 can provide effective protection for the image sensor IMAGE. The protective glass 7 can be set as a filter, and the filter can effectively filter out stray light in non-working wavelength bands to reduce optical noise, making it easier for the subsequent optoelectronic module processing part and thus improving the imaging quality. It can be understood that the surface of the image sensor chip 8 facing the object side is the imaging surface.

[0047] Specifically, the imaging surface can be understood as the surface of the image sensor chip 8 facing the object side, that is, it can be the surface of imaging elements such as CCD or CMOS. It can be understood that the light carrying the information of the object to be photographed can pass through the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, and the fifth lens 5 in sequence and finally form an image on the imaging surface.

[0048] Specifically, in this embodiment, the refractive index, curvature radius, and thickness interval of the lens materials are shown in Table 1 below:

[0049] Table 1

[0050]

[0051]

[0052] Specifically, in this embodiment, the second lens 2, the fourth lens 4, and the fifth lens 5 are aspherical lenses. The characteristics of aspherical lenses are that the curvature changes continuously from the center of the lens to the periphery of the lens. Different from spherical lenses with a constant curvature from the center of the lens to the periphery of the lens, aspherical lenses have better curvature radius characteristics and have the advantages of improving distortion aberration and astigmatism aberration. And the chromatic aberration of the lens can be well corrected through aspherical lenses. While ensuring the control of purple fringing of the lens, the spherical aberration and sine aberration at high magnification positions can be corrected simultaneously.

[0053] Further, in this embodiment, the aspherical surface shape of the aspherical lens satisfies the following conditions:

[0054]

[0055] Wherein, c is the curvature corresponding to the radius, y is the radial coordinate (with the same unit as the lens length unit), k is the conic quadratic curve coefficient (when the k coefficient is less than -1, the surface curve is a hyperbola; when the k coefficient is equal to -1, it is a parabola; when the k coefficient is between -1 and 0, it is an ellipse; when the k coefficient is equal to 0, it is a circle; when the k coefficient is greater than 0, it is an oblate circle), a1, a2, a3, a4, a5, a6, a7 are high-order aspherical coefficients (please refer to Table 2 below). The shape and size of the aspherical surfaces on the object side and image side of the lens can be set through the above parameters.

[0056] Table 2 Conic coefficients and aspherical coefficients corresponding to aspherical lenses:

[0057]

[0058]

[0059] Figure 2 It is a schematic diagram of the spherical aberration curve of an embodiment of a fixed-focus lens provided by the present invention. Figure 3 It is a schematic diagram of the light fan of an embodiment of a fixed-focus lens provided by the present invention. Figure 4 It is a schematic diagram of the field distortion / field curvature of an embodiment of a fixed-focus lens provided by the present invention.

[0060] As can be seen from the above figures, the spherical aberration, field curvature, and distortion of the fixed-focus lens in this embodiment can all be well corrected.

[0061] In summary, the aperture value F of the fixed-focus lens satisfies 1.8 ≤ F ≤ 2.2, and it does not defocus at high and low temperatures, and the field of view angle can reach 170°.

[0062] The present invention also provides an intelligent door lock, which includes the fixed-focus lens described in the above technical solution. The specific structure of this fixed-focus lens refers to the above embodiment. Since the fixed-focus lens of this fixed-focus lens adopts all the technical solutions of the above all embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, and will not be elaborated here one by one.

[0063] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structural transformation made under the inventive concept of the present invention, or direct / indirect application in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A fixed-focus lens for an intelligent door lock, characterized in that, The fixed-focus lens has an object side and an image side that are oppositely arranged along the optical axis direction. The fixed-focus lens includes a first lens with a negative optical power, a second lens with a positive optical power, a diaphragm, a third lens with a positive optical power, a fourth lens with a negative optical power, and a fifth lens with a positive optical power, which are arranged in sequence from the object side to the image side. The fixed-focus lens satisfies the following conditions: 0.97 < |f1 / f| < 1.82, and 7.2 < |f2 / f| < 13.4, and 1.1 < |f3 / f| < 2.1, and 1.1 < |f4 / f| < 2.1, and 1.0 < |f5 / f| < 2.0; where f is the total focal length of the fixed-focus lens, f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, and f5 is the focal length of the fifth lens; The overall optical length of the fixed-focus lens satisfies 9mm < TTL < 17mm; The radius of curvature of the object side surface of the first lens is 11.58mm, the thickness of the first lens is 0.56mm, the radius of curvature of the image side surface of the first lens is 1.81mm, the distance from the image side surface of the first lens to the object side surface of the second lens is 1.68mm, the radius of curvature of the object side surface of the second lens is -3.42mm, the thickness of the second lens is 1.48mm, the radius of curvature of the image side surface of the second lens is -3.33mm, the distance from the image side surface of the second lens to the object side surface of the third lens is 0.06mm, the radius of curvature of the object side surface of the third lens is 5.29mm, the thickness of the third lens is 2.43mm, the radius of curvature of the image side surface of the third lens is -3.16mm, the distance from the image side surface of the third lens to the object side surface of the fourth lens is 0.36mm, the radius of curvature of the object side surface of the fourth lens is 9.85mm, the thickness of the fourth lens is 0.5mm, the radius of curvature of the image side surface of the fourth lens is 1.93mm, the distance from the image side surface of the fourth lens to the object side surface of the fifth lens is 0.17mm, the radius of curvature of the object side surface of the fifth lens is 3.45mm, the thickness of the fifth lens is 1.8mm, and the radius of curvature of the image side surface of the fifth lens is -3.63mm.

2. The fixed-focus lens according to claim 1, wherein The first lens and the third lens are glass spherical lenses; The second lens, the fourth lens, and the fifth lens are plastic aspherical lenses.

3. The fixed-focus lens according to claim 1, wherein The diaphragm and the fixed-focus lens satisfy the following conditions: 0.5 < SD / TTL < 0.94; where SD is the distance between the diaphragm and the imaging surface of the fixed-focus lens on the optical axis, and TTL is the overall optical length of the fixed-focus lens.

4. The fixed-focus lens according to claim 1, characterized in that, The fixed-focus lens satisfies the following conditions: 3.7 < TTL / f < 7; where TTL is the overall optical length of the fixed-focus lens.

5. The fixed-focus lens according to claim 1, characterized in that, The Abbe number vd4 of the fourth lens satisfies: 20 < vd4 < 40.

6. The fixed-focus lens according to claim 1, wherein, The Abbe number vd5 of the fifth lens satisfies: 40 < vd5 < 70.

7. The fixed-focus lens according to claim 1, wherein The fixed-focus lens further includes a protective glass and an image sensor chip in sequence from the object side to the image side, and the protective glass and the image sensor chip are disposed on a side of the fifth lens close to the image side.

8. An intelligent door lock, characterized in that, A fixed-focus lens includes the fixed-focus lens according to any one of claims 1 to 7.

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