Fresnel lens and infrared detection device suitable for long-distance detection

Abstract

The utility model provides a Fresnel lens suitable for long-distance detection and an infrared detection device, and the Fresnel lens comprises a central lens which is provided with at least one lens unit and has a central axis, and two lens unit groups which are composed of a plurality of lens units and are disposed around the central lens. Wherein the focal length of the lens unit of the central lens is f, the distance between the optical center of the lens unit farthest from the central axis in the lens units of the lens unit group and the central axis is L, and the Fresnel lens is designed in a state that L is less than or equal to 18 mm, f is greater than or equal to 15 mm, and H is less than or equal to 10 mm to meet the condition that L / (f-H) is less than or equal to 0.7, wherein H is the height difference between the optical center of the lens unit of the central lens and the optical center of the lens unit farthest from the central axis in the lens units of the lens unit group in the direction of the central axis; therefore, the Fresnel lens can give consideration to the miniaturization design of the infrared detection device and the effective detection area in a long-distance detection application scene at the same time.

Description

TECHNICAL FIELD

[0001] The utility model relates to infrared detection field more detailedly relates to a kind of Fresnel lens and infrared detection device suitable for long-distance detection. BACKGROUND

[0002] With the development of Internet of Things technology and the popularization of low-carbon environmental protection concept, artificial intelligence, smart home and intelligent security technology have increasing demand for environmental detection, especially for human movement detection. The intelligent control of the working state of electrical equipment is realized by controlling the corresponding electrical equipment based on the detection result of human presence or absence, for example, the intelligent low-carbon lighting is realized by controlling the lighting state of the luminaire based on the detection result of human presence or absence.

[0003] The existing technology for detecting human presence mainly includes: 1. Image acquisition based on corresponding algorithm to identify human body and human behavior state, but due to the risk of invasion and leakage of privacy, it is difficult to be accepted, and at the same time, it has the defects of complex algorithm and high requirement for hardware performance, so it has high cost. 2. Microwave detection technology based on Doppler effect principle, specifically by emitting microwave beam and receiving the reflected echo formed by the reflection of the corresponding object, and generating a Doppler intermediate frequency signal corresponding to the frequency difference between the microwave beam and the reflected echo by means of mixing detection, the Doppler intermediate frequency signal is the feedback of the movement of the corresponding object. The microwave detection technology based on Doppler effect principle has unique advantages in behavior detection and presence detection technology, which can detect moving objects without invading human privacy, so it has wide application prospect. But on the one hand, limited by the working principle of microwave detection technology, the current microwave detection device cannot maintain its advantage of detecting micro-motion in the application scene of long-distance detection due to the influence of environment, on the other hand, limited by the product volume, cost and microwave emission power of civil level microwave detection device, the beam angle and corresponding detection distance of the microwave beam emitted by the existing microwave detection device are difficult to be accurately designed and controlled like military phased array radar. 3. Based on the zoning of the corresponding detection area by Fresnel lens, the cross-zone action of human body in the detection area is detected by pyroelectric infrared sensor (PIR), which is also the most commonly used and mature human presence detection technology at present.

[0004] Although the third human existence detection technology among the foregoing three human existence detection technologies is the most popular and mature human existence detection technology at present, the current corresponding infrared detection device suitable for long-distance detection of more than 12 meters generally has the defect of large volume, so that when it is applied to intelligent lighting, the infrared detection device can only be set in an external hanging manner, and the volume of the externally hung infrared detection device can be larger than that of the lamp itself. The reason why the volume of the current infrared detection device suitable for long-distance detection is large is mainly that in the current product design idea of the infrared detection device, the increase of the detection distance is realized by the technical route of increasing the total light amount. Based on this technical route, the corresponding Fresnel lens is generally designed to have a large light incidence angle and a large light incidence surface area, so as to increase the total light amount based on the design of a large light incidence angle and a large light incidence surface area, increase the capture amount of infrared light radiated by a human body at a long distance by the pyroelectric infrared sensor, and further improve the detection distance of the infrared detection device. The Fresnel lens with a large light incidence angle and a large light incidence surface area is also designed to have a convex light incidence surface shape, and the center of the light incidence surface of the Fresnel lens has a height difference of more than 15 mm relative to the periphery based on the convex structure design. In this way, the Fresnel lens has a large light incidence surface area, and the periphery diameter of the Fresnel lens is reduced (actually still more than 80 mm) based on the convex light incidence surface shape design to reduce the lateral size of the infrared detection device; and the Fresnel lens has a large light incidence angle, and each lens unit can be designed with a larger focal length based on the convex light incidence surface shape design to reduce the overall thickness of the Fresnel lens, which corresponds to reducing the loss of infrared light when the infrared light passes through the Fresnel lens, thereby facilitating further increase of the capture amount of infrared light radiated by a human body at a long distance by the pyroelectric infrared sensor and ensuring the detection distance of the infrared detection device. Utility model content

[0005] The purpose of the present utility model is to provide a Fresnel lens and an infrared detection device suitable for long-distance detection, wherein the Fresnel lens is suitable for long-distance detection of more than 15 meters, and has a significantly reduced volume compared with the existing Fresnel lens suitable for long-distance detection, thereby having great commercial value.

[0006] The purpose of the present utility model is to provide a Fresnel lens and an infrared detection device suitable for long-distance detection, wherein the Fresnel lens is suitable for long-distance detection of more than 15 meters, and has a significantly reduced volume compared with the existing Fresnel lens suitable for long-distance detection, thereby having great commercial value.

[0007] The utility model discloses another purpose lies in providing a kind of Fresnel lens and infrared detection device suitable for long-distance detection, wherein the Fresnel lens is increased by the technical route of the proportion of effective light energy in the light quantity to realize the increase of detection distance, corresponding to the feature that effective light energy decreases with the target to be detected away from the infrared detection device, by the way of reducing the light angle of the Fresnel lens, the distance variation range between the target to be detected in target detection space and the infrared detection device is reduced, and then the proportion of effective light energy in the light quantity is increased, so it is completely different from the technical route of traditional total light quantity to avoid the design of large light angle and light area.

[0008] The utility model discloses another purpose lies in providing a kind of Fresnel lens and infrared detection device suitable for long-distance detection, wherein the vertical detection application scene of the infrared detection device is taken as an example, although the light angle of the Fresnel lens is increased, but the distance variation between the target to be detected in target detection surface (ground) and the infrared detection device is formed by the movement of the target to be detected, and the target to be detected is away from the infrared detection device when the projection point on the target detection surface is away from the infrared detection device, so, based on the feature that effective light energy decreases with the target to be detected away from the infrared detection device, by the way of reducing the light angle of the Fresnel lens, the distance variation range between the target to be detected in target detection space and the infrared detection device is reduced, so the proportion of effective light energy in the light quantity can be increased, and it is completely separated from the technical route of traditional total light quantity.

[0009] The utility model discloses another purpose lies in providing a kind of Fresnel lens and infrared detection device suitable for long-distance detection, wherein the structure design of the Fresnel lens is based on the technical route of the proportion of effective light energy in the light quantity to have smaller light angle design, and smaller light area design is suitable for being used in the state of smaller light angle design, so it is suitable for more long-distance detection, and also has smaller volume, so it can reduce cost and adapt to the miniaturization trend of product compared with the existing Fresnel lens suitable for long-distance detection.

[0010] The utility model discloses another purpose lies in providing a kind of Fresnel lens and infrared detection device suitable for long-distance detection, wherein the structure design of the Fresnel lens is based on the technical route of the proportion of effective light energy in the light quantity to have smaller light angle and light area design, so it has smaller peripheral diameter without the light surface form design based on convex, and each lens unit is designed with larger focal length to reduce the overall thickness of the Fresnel lens, which is conducive to increasing the capture amount of infrared light radiated by the target to be detected at a long distance by the corresponding pyroelectric infrared sensor, and ensuring the detection distance of the infrared detection device.

[0011] The other purpose of the present application is to provide a Fresnel lens and infrared detection device suitable for long-distance detection, wherein the structure design of the Fresnel lens has a smaller light inlet angle and light inlet surface area design based on the technical route of improving the proportion of effective light energy in the light inlet amount, thus without the light inlet surface form design based on the convex, the Fresnel lens has good structural stability, which is beneficial to ensure the working stability of the infrared detection device.

[0012] The other purpose of the present application is to provide a Fresnel lens and infrared detection device suitable for long-distance detection, wherein the Fresnel lens has a smaller peripheral diameter and each lens unit is designed with a larger focal length to reduce the overall thickness of the Fresnel lens, and the height difference of the light inlet surface center of the Fresnel lens relative to its periphery is allowed to be set in a range less than 10mm and can be designed as a plane or a micro-arc surface, thus having a more natural and concealed installation effect.

[0013] The other purpose of the present application is to provide a Fresnel lens and infrared detection device suitable for long-distance detection, wherein the Fresnel lens has a center lens, and at least one lens unit group is arranged around the center lens, and the light inlet surface of the Fresnel lens is formed by the smooth surface of the center lens and the lens unit group, wherein the center lens is provided with at least one lens unit and has a central axis, and the distance between the optical center of the lens unit farthest from the central axis in the lens unit group and the central axis is L, and based on the technical route of improving the proportion of effective light energy in the light inlet amount, the Fresnel lens of the present application has a smaller light inlet angle and the distance L is set in a range less than or equal to 18mm, thus having a significantly reduced volume compared with the existing Fresnel lens suitable for long-distance detection.

[0014] The other purpose of the present application is to provide a Fresnel lens and infrared detection device suitable for long-distance detection, wherein the focal length of the lens unit of the center lens is f, the Fresnel lens is designed in a state of L≤18mm, f≥15mm, and H≤10mm, and L / (f-H)≤0.7, wherein H is the height difference between the optical center of the lens unit of the center lens and the optical center of the lens unit farthest from the central axis in the lens unit group in the direction of the central axis, so that the light inlet angle of the Fresnel lens when applied to the infrared detection device is less than or equal to 70°, and the Fresnel lens has a smaller light inlet surface area while having a smaller light inlet angle.

[0015] To achieve the above at least one object, the utility model provides an infrared detection device suitable for long distance detection, the infrared detection device includes:

[0016] A Fresnel lens, wherein the Fresnel lens has a center lens and two groups of lens unit groups, wherein the center lens is provided with at least one lens unit and has a central axis, each of the lens unit groups is composed of a plurality of lens units and is arranged around the center lens, one of the lens unit groups is arranged around the center lens with the outer edge of the center lens as the inner edge, and the other lens unit group is arranged around the center lens with the outer edge of the previous lens unit group as the inner edge, wherein the total number of the lens units of the two lens unit groups is designed to be less than or equal to 16, the Fresnel lens forms a light entrance surface with the smooth surface of each lens unit, and each lens unit of the Fresnel lens is designed with a plurality of concentric circular lines on the side opposite to the light entrance surface, so as to have the light condensing characteristics of a convex lens, wherein the focal length of the lens unit of the center lens is f, the distance between the optical center of the lens unit farthest from the central axis in the lens unit group and the central axis is L, the Fresnel lens is designed in the state of L <= 18mm, f >= 15mm and H <= 10mm, and L / (f-H) <= 0.7 is satisfied, wherein H is the height difference between the optical center of the lens unit of the center lens and the optical center of the lens unit farthest from the central axis in the lens unit group in the direction along the central axis; and

[0017] At least one pyroelectric infrared sensor, wherein the pyroelectric infrared sensor has at least one sensing surface and is arranged with the sensing surface facing the side of the Fresnel lens opposite to the light entrance surface.

[0018] In an embodiment, wherein the number of the lens units of the center lens is one, and the center lens has the principal optical axis of the lens unit thereof as the central axis.

[0019] In an embodiment, wherein the number of the lens units of the lens unit group with the outer edge of the center lens as the inner edge is four, and the number of the lens units of the other lens unit group is eight.

[0020] In an embodiment, wherein the center lens provided with one lens unit has a square outer edge, the lens unit group with the outer edge of the center lens as the inner edge has an octagonal outer edge, and the four lens units are divided by the extension line of the diagonal of the square inner edge, and the other lens unit group has a circular outer edge with the outer edge of the previous lens unit group as the inner edge, and the eight lens units are divided by the diagonal extension line of the octagonal inner edge.

[0021] In an embodiment, wherein a square outer edge of the center lens has a side length of 6±0.5mm, an octagonal outer edge of the lens unit group with the outer edge of the center lens as an inner edge has a side length of 7±0.5mm, and a circular outer edge of another lens unit group has a radius of 17.5±0.5mm.

[0022] In an embodiment, wherein the optical center of the lens unit of each lens unit group is designed to deviate from the geometric center of the lens unit in a direction deviated from the center lens.

[0023] In an embodiment, wherein the lens unit of the lens unit group in the outer periphery has a larger smooth surface area as it is further away from the center lens.

[0024] In an embodiment, wherein the Fresnel lens is further designed to satisfy L / (f-H)≤0.7 in a state of 11mm≤L≤13mm, 21mm≤f≤25mm, and H≤5mm.

[0025] In an embodiment, wherein the pyroelectric infrared sensor is arranged in a quadrupole form.

[0026] According to another aspect of the present application, the present application further provides a Fresnel lens suitable for long-distance detection, the Fresnel lens comprising:

[0027] a center lens, wherein the center lens is arranged with at least one lens unit and has a central axis; and

[0028] Two lens unit groups, wherein each of the lens unit groups is arranged around the center lens in a plurality of lens units, and one of the lens unit groups is arranged around the center lens with the outer edge of the center lens as the inner edge, and the other of the lens unit groups is arranged around the center lens with the outer edge of the one of the lens unit groups as the inner edge, wherein the total number of the lens units of the two lens unit groups is designed to be less than or equal to 16, and the optical center of the lens unit of each of the lens unit groups is designed to deviate from the geometric center of the lens unit in the direction of the center lens, wherein the Fresnel lens is formed with a smooth surface of each lens unit as a light entrance surface, and each of the lens units of the Fresnel lens is designed with a plurality of concentric circular patterns on the side opposite to the light entrance surface to have a light converging property of a convex lens, wherein the focal length of the lens unit of the center lens is f, the distance between the optical center of the lens unit farthest from the central axis among the lens units of the two lens unit groups and the central axis is L, the Fresnel lens is designed in a state of L≤18mm, f≥15mm, and H≤10mm, and L / (f-H)≤0.7 is satisfied, wherein H is the height difference between the optical center of the lens unit of the center lens and the optical center of the lens unit farthest from the central axis among the lens units of the lens unit group in the direction along the central axis.

[0029] Further purposes and advantages of the present application will be fully understood from the following description and drawings. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 It is a schematic diagram of the vertical detection application scene of the existing infrared detection device.

[0031] Figure 2A It is a schematic diagram of the structure principle of an infrared detection device according to an embodiment of the present application.

[0032] Figure 2B It is a schematic diagram of the refraction principle of the lens unit of the Fresnel lens of the infrared detection device according to the above embodiment of the present application.

[0033] Figure 3A It is a schematic diagram of the shape of the Fresnel lens of the infrared detection device according to the above embodiment of the present application on the light entrance surface.

[0034] Figure 3B It is a schematic diagram of the shape of the Fresnel lens of the infrared detection device according to the above embodiment of the present application on the side opposite to the light entrance surface.

[0035] Figure 4 It is a schematic diagram of the shape of a lens unit in which the optical center is not located in the lens unit body.

[0036] Figure 5A The application scenario schematic diagram of the infrared detection device in the above embodiment of the present application is implemented in a warehouse environment to realize intelligent lighting in a state of being installed in a lamp.

[0037] Figure 5B The effect display diagram of the infrared detection device in the above embodiment of the present application is installed in a lamp. DETAILED DESCRIPTION

[0038] The following description is provided to enable any person skilled in the art to make and use the present application. The preferred embodiments in the following description are only examples and other obvious modifications are possible to those skilled in the art. The basic principles defined in the following description can be applied to other embodiments, variations, improvements, equivalents and other technical solutions without departing from the spirit and scope of the present application.

[0039] Those skilled in the art should understand that in the disclosure of the present application, the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like are based on the orientation or positional relationship shown in the drawings, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, therefore the above terms cannot be understood as a limitation of the present application.

[0040] It can be understood that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of one element can be one, and in another embodiment, the number of the element can be multiple, and the term "one" cannot be understood as a limitation of the number.

[0041] The present application provides a Fresnel lens and infrared detection device suitable for long-distance detection, wherein the Fresnel lens is suitable for long-distance detection of 15 meters and above, and has a significantly reduced volume compared to the existing Fresnel lens suitable for long-distance detection, thus having great commercial value.

[0042] Specifically, the application increases the detection distance by improving the proportion of effective light energy in the light quantity of the Fresnel lens when the Fresnel lens is applied to the infrared detection device, and reduces the distance change range between the detected target and the infrared detection device in the target detection space by reducing the light incidence angle of the Fresnel lens, thereby increasing the proportion of effective light energy in the light quantity, and avoiding the design of large light incidence angle and light incidence area.

[0043] For example, referring to the drawings of the specification of the application Figure 1 As shown in the drawings, taking the vertical detection application scene of the existing infrared detection device as an example, the movement of the detected target on the target detection surface (ground) will form a distance change between the infrared detection device, and the detected target will move away from the infrared detection device when the projection point on the target detection surface is away from the infrared detection device. Therefore, based on the characteristic that the effective light energy decreases as the detected target moves away from the infrared detection device, although a larger light quantity can be obtained by increasing the light incidence angle of the Fresnel lens, the distance between the detected target and the infrared detection device in the target detection space formed by the increased light incidence angle is also far away, that is, the proportion of effective light energy in the light quantity increased by increasing the light incidence angle is relatively low, and thus the proportion of effective light energy in the total light quantity is reduced. Therefore, the application reduces the distance change range between the detected target and the infrared detection device in the target detection space by reducing the light incidence angle of the Fresnel lens, thereby increasing the proportion of effective light energy in the light quantity, and completely departing from the traditional technical route of increasing the total light quantity.

[0044] Further referring to the drawings of the specification of the application Figures 2A to 3BAs shown, the structure principle of the infrared detecting device and the corresponding structure of the Fresnel lens according to an embodiment of the present application are shown respectively, wherein the infrared detecting device comprises a Fresnel lens 10 and at least one pyroelectric infrared sensor 20, wherein the Fresnel lens 10 has a center lens 11 with at least one lens unit 100 arranged and having a central axis, and at least one lens unit group 12 composed of a plurality of lens units 100 and arranged around the center lens 11, the Fresnel lens 10 corresponding to each smooth surface of the lens unit 100 forms a light entrance surface 101, and each lens unit 100 of the Fresnel lens 10 is designed with a plurality of concentric circular lines on the side opposite to the light entrance surface 101, so as to have the light condensing characteristics of a convex lens, wherein the focal length of the lens unit 100 of the center lens 11 is f, and the distance between the optical center of the lens unit 100 farthest from the central axis in the lens unit group 12 and the central axis is L, wherein the pyroelectric infrared sensor 20 has at least one sensing surface 21 and is arranged such that the sensing surface 21 faces the side of the Fresnel lens 10 opposite to the light entrance surface 101.

[0045] Corresponding to Figure 2B As shown, the refractive principle of the lens unit 100, the lens unit 100 has the same optical characteristics as a convex lens and has an optical center 1001 and a principal axis 1002 passing through the optical center 1001, and the light rays parallel to the principal axis 1002 of the lens unit 100 are converged at the focal point 1003 of the lens unit 100 by refraction of the lens unit 100, wherein the focal plane 1004 of the lens unit 100 is the plane perpendicular to the principal axis 1002 of the lens unit 100 in the plane where the focal point 1003 of the lens unit 100 is located, and the axis passing through the optical center 1001 of the lens unit 100 and inclined to the principal axis 1002 is the secondary principal axis 1005 of the lens unit 100, wherein the light rays parallel to the secondary principal axis 1005 of the lens unit 100 are converged at the secondary focal point 1006 on the focal plane 1004 of the lens unit 100 by refraction of the lens unit 100.

[0046] According to the above refraction principle of the lens unit 100, the sensing surface 21 of the pyroelectric infrared sensor 20 is generally arranged near the focal plane 1004 of the lens unit 100 of the center lens 11, corresponding to the state that the number of the lens unit 100 of the center lens 11 is one, the central axis of the center lens 11 is the main optical axis 1002 of the lens unit 100, and the distance between the optical center 1001 of the lens unit 100 and the sensing surface 21 of the pyroelectric infrared sensor 20 along the central axis of the center lens 11 is close to the focal length f of the lens unit 100; and in the state that the number of the lens unit 100 of the center lens 11 is multiple, the distance between the optical center 1001 of any lens unit 100 of the center lens 11 and the sensing surface 21 of the pyroelectric infrared sensor 20 along the central axis of the center lens 11 is also close to the focal length f of the lens unit 100. Therefore, in the understanding of the present application, the light incidence angle θ of the Fresnel lens 10 when applied to the infrared detection device corresponds to Figure 2A For the right-angled triangle composed of two straight-angled sides with lengths of (f-H) and L, twice the angle of the angle opposite to the straight-angled side with length L, wherein H is the height difference between the optical center 1001 of the lens unit 100 of the center lens 11 and the optical center 1001 of the lens unit 100 farthest from the central axis in the lens unit group 12 along the central axis, and the light incidence angle θ of the Fresnel lens 10 satisfies tan(θ / 2)=L / (f-H).

[0047] It is worth mentioning that, affected by the area and number of the sensing surface 21 of the pyroelectric infrared sensor 20 and the actual installation position and angle error of the pyroelectric infrared sensor 20, in the understanding of the present application, the light incidence angle θ defined based on L / (f-H) is only used to define the structural characteristics of the Fresnel lens 10, which neither constitutes a limitation on the specific installation position and angle of the pyroelectric infrared sensor 20, nor constitutes a limitation on the actual effective detection angle of the infrared detection device.

[0048] Particularly, the utility model discloses a technical route of improving the proportion of effective light energy in the light quantity of the Fresnel lens 10 when being applied to the infrared detection device to realize the increase of the detection distance, in which, on the one hand, the light entrance area of the Fresnel lens 10 is not a decisive factor affecting the proportion of effective light energy in the light quantity. On the other hand, when the structure design of the Fresnel lens 10 is based on the aforementioned technical route of the utility model and has a small light entrance angle design, and still corresponds to the traditional technical route of increasing the total light quantity and has a large light entrance area, in order to reduce the overall thickness of the Fresnel lens 10 to reduce the loss of infrared light when passing through the Fresnel lens 10 and to ensure the detection distance of the infrared detection device, each lens unit 100 of the Fresnel lens 10 is necessarily designed to have a large focal length, so that the size of the infrared detection device in the central axis direction of the central lens 11 is also very large.

[0049] That is, when the structure design of the Fresnel lens 10 is based on the aforementioned technical route of the utility model and has a small light entrance angle design, and still corresponds to the traditional technical route of increasing the total light quantity and has a large light entrance area, in order to ensure the detection distance of the infrared detection device, the size of the infrared detection device in the central axis direction of the central lens 11 and the overall thickness of the Fresnel lens 10 cannot be reduced at the same time.

[0050] Therefore, in the structure design of the Fresnel lens 10 of the utility model, when the structure design of the Fresnel lens 10 is based on the aforementioned technical route of the utility model and has a small light entrance angle design, the Fresnel lens 10 also has a small light entrance area design, so that the structure design of the Fresnel lens 10 can simultaneously consider the miniaturization design and long-distance detection of the infrared detection device.

[0051] Specifically, in the structure design of the Fresnel lens 10 of the utility model, the Fresnel lens 10 is designed to be in a state of L≤18mm, f≥15mm, and H≤10mm, and satisfies L / (f-H)≤0.7, so that the light entrance angle θ of the Fresnel lens 10 when being applied to the infrared detection device is less than or equal to 70°, and the Fresnel lens 10 has a small light entrance area in the state of having a small light entrance angle, thereby enabling the structure design of the Fresnel lens 10 to simultaneously consider the miniaturization design and long-distance detection of the infrared detection device.

[0052] In other words, in the state that the structure design of the Fresnel lens 10 is based on the aforementioned technical route of the utility model and has a small light incidence angle design, the Fresnel lens 10 of the utility model can simultaneously consider the small area design of the light incidence surface 101 and the thinning design of the overall thickness in the structure design, so that the structure design of the Fresnel lens 10 can simultaneously consider the miniaturization design and the long-distance detection of the infrared detection device.

[0053] It is worth mentioning that, although in the state that the structure design of the Fresnel lens 10 is based on the aforementioned technical route of the utility model and has a small light incidence angle design, the Fresnel lens 10 of the utility model can simultaneously consider the small area design of the light incidence surface 101 and the thinning design of the overall thickness in the structure design. However, the small area design of the light incidence surface 101 of the Fresnel lens 10 will indeed lead to a decrease in the total light incidence amount and a decrease in the intensity of the total effective light energy. Therefore, in order to guarantee the detection distance of the infrared detection device, in the structure design of the Fresnel lens 10 of the utility model, the number of the lens unit groups 12 of the Fresnel lens 10 is two, one of which is arranged around the center lens 11 with the outer edge of the center lens 11 as the inner edge, and the other is arranged around the center lens 11 with the outer edge of the previous lens unit group 12 as the inner edge, and the total number of the lens units 100 of the two lens unit groups 12 is designed to be less than or equal to 16. In this way, in the state that the light incidence surface 101 of the Fresnel lens 10 has a small area based on the conditions of L≤18mm and H≤10mm, the light incidence area of the lens units 100 of each lens unit group 12 is guaranteed, so that the intensity of the effective light energy passing through the lens units 100 of each lens unit group 12 is not reduced due to the small area design of the light incidence surface 101 of the Fresnel lens 10, thereby guaranteeing the detection distance of the infrared detection device.

[0054] Specifically, in the structure example of the Fresnel lens 10 of this embodiment of the utility model, the total number of the lens units 100 of the two lens unit groups 12 is 12, so as to guarantee the light incidence area of the lens units 100 of each lens unit group 12 and the intensity of the effective light energy passing through the lens units 100 of each lens unit group 12, and simultaneously consider the number of the lens units 100 of the lens unit group 12, so that in the state that the Fresnel lens 10 has a small light incidence angle, based on the characteristics that the target detection surface is far away from the infrared detection device in the long-distance detection application scenario, the Fresnel lens 10 still has a large partition coverage area and a reasonable partition arrangement density, thereby guaranteeing the effective detection area of the infrared detection device.

[0055] Briefly, the infrared detection device is based on the division of the corresponding detection area by the lens unit 100 of the Fresnel lens 10 for the pyroelectric infrared sensor 20 to detect the cross-zone action of the human body in the detection area. Therefore, in the state that the Fresnel lens 10 has a small light incidence angle design, and the light incidence surface 101 has a small area based on the condition of L≤18mm and H≤10mm, the number of the lens unit groups 12 of the Fresnel lens 10 is designed to be two groups, and the total number of the lens units 100 of the two lens unit groups 12 is designed to be less than or equal to 16, on the one hand, the light incidence area of the lens unit 100 of each lens unit group 12 can be guaranteed, so that the effective light energy intensity of the light passing through the lens unit 100 of each lens unit group 12 is not reduced due to the small area design of the light incidence surface 101 of the Fresnel lens 10, thereby guaranteeing the detection distance of the infrared detection device; on the other hand, the characteristics that the target detection surface is far away from the infrared detection device in the long-distance detection application scene can be utilized, so that the Fresnel lens 10 still has a large partition coverage area and a reasonable partition arrangement density, thereby guaranteeing the effective detection area of the infrared detection device.

[0056] In summary, the Fresnel lens 10 of the utility model needs to meet L≤18mm, f≥15mm, H≤10mm and L / (f-H)≤0.7 in the structural design, and at the same time, the number of the lens unit groups 12 is designed to be two groups, and the total number of the lens units 100 of the two lens unit groups 12 is designed to be less than or equal to 16, so that the light incidence angle θ of the Fresnel lens 10 is less than or equal to 70° when it is applied to the infrared detection device, and the Fresnel lens 10 has a small light incidence surface area while having a small light incidence angle, and is suitable for long-distance detection of 15 meters and above. Correspondingly, the structural design of the Fresnel lens 10 can simultaneously consider the miniaturization design of the infrared detection device and the effective detection area in the long-distance detection application scene.

[0057] It is worth mentioning that, in the description of the utility model, the description of the detection distance range suitable for the Fresnel lens 10 is only to emphasize the farthest detection distance range in which the Fresnel lens 10 can be normally used in performance. That is to say, the farthest detection distance in which the Fresnel lens 10 of the utility model can be normally used in performance can reach 15 meters and above, which does not constitute a limitation on the actual use state of the Fresnel lens 10, for example, the Fresnel lens 10 of the utility model is recommended to be used for long-distance detection of 15 meters and above, and is not recommended to be used for short-distance detection of less than 8 meters, but according to the actual use demand, the user can still use it for detection in the distance range of 8 to 15 meters, and the utility model does not limit this.

[0058] Further, in the state that the Fresnel lens 10 is designed to satisfy L≤18mm, f≥15mm, H≤10mm and L / (f-H)≤0.7, and the number of the lens unit groups 12 is designed to be two groups, and the total number of the lens units 100 of the two groups of the lens unit groups 12 is designed to be less than or equal to 16, the Fresnel lens 10 is preferably designed to satisfy that, taking the center lens 11 as the center, the lens units 100 of the lens unit groups 12 in the outer periphery have larger light inlet areas (i.e. the area of the aforementioned smooth surface), so as to guarantee the intensity and uniformity of the effective light energy of the lens units 100 of each group of the lens unit groups 12, thereby guaranteeing the stability of the detection sensitivity of the infrared detection device in the effective detection area.

[0059] Specifically, in the structure example of the Fresnel lens 10 of this embodiment of the utility model, the number of the lens units 100 of the center lens 11 is one, as shown in the structure form of Figure 3A and Figure 3B The main optical axis 1002 of the lens unit 100 of the center lens 11 is taken as the central axis, wherein the Fresnel lens 10 is designed to satisfy L / (f-H)≤0.7 in the state of 11mm≤L≤13mm, 21mm≤f≤25mm and H≤5mm, based on which, the overall thickness of the Fresnel lens 11 is allowed to be designed in the thickness range of less than or equal to 0.6mm, so as to take into account the miniaturization design and long-distance detection of the infrared detection device.

[0060] Further, in the structure example of the Fresnel lens 10 of this embodiment of the utility model, the number of the lens units 100 of the lens unit group 12 with the outer edge of the center lens 11 as the inner edge is four, and the number of the lens units 100 of the other lens unit group 12 is eight.

[0061] Specifically, in the structural example of the Fresnel lens 10 of this embodiment of the present application, the center lens 11 with one lens unit 100 arranged has a square outer edge, the lens unit group 12 with the outer edge of the center lens 11 as the inner edge has a regular octagonal outer edge, and the four lens units 100 are divided by the diagonal extension line of the square inner edge, and the other lens unit group 12 has a circular outer edge with the outer edge of the previous lens unit group 12 as the inner edge, and the eight lens units 100 are divided by the diagonal extension line of the regular octagonal inner edge.

[0062] Further, in the structural example of the Fresnel lens 10 of this embodiment of the present application, the square outer edge of the center lens 11 has a side length of 6±0.5mm, the regular octagonal outer edge of the lens unit group 12 with the outer edge of the center lens 11 as the inner edge has a side length of 7±0.5mm, and the circular outer edge of the other lens unit group 12 has a radius of 17.5±0.5mm, so as to ensure the uniformity of the effective light energy intensity of the lens units 100 of each lens unit group 12, thereby ensuring the stability of the detection sensitivity of the infrared detection device within the effective detection area, and when the Fresnel lens 10 has the outer edge of the light entrance face 101 as the circumference, the circumference diameter is only about 35mm, which is much smaller than the circumference diameter of the conventional Fresnel lens applied to long-distance detection.

[0063] Particularly, in the structural example of the Fresnel lens 10 of this embodiment of the present application, each lens unit 100 of the Fresnel lens 10 is designed with a plurality of concentric circular lines on the side opposite to the light entrance face 101, which has the light-gathering property of a convex lens, and the optical center 1001 of the lens unit 100 can be considered as the center of the concentric circular lines within a certain error range. Since the sensing face 21 of the pyroelectric infrared sensor 20 is usually arranged near the focal plane 1004 of the lens unit 100 of the center lens 11, in order to make the light passing through the lens unit 100 of the lens unit group 12 be able to deviate to the sensing face 21 of the pyroelectric infrared sensor 20, the optical center 1001 of the lens unit 100 of the lens unit group 12 is usually designed to deviate from the geometric center of the lens unit 100 in the direction deviating from the center lens 11.

[0064] That is, the convex lens optically equivalent to the lens unit 100 of the lens unit group 12 based on the design of concentric circle lines is not limited to a convex lens with the geometric center as the optical center 1001, and can be equivalent to a defective form of a convex lens with the geometric center as the optical center 1001. Therefore, in some embodiments of the present application, the concentric circle lines designed in the lens unit 100 correspond to Figure 4 It is not limited to having at least one complete circular line, and the optical center 1001 of the lens unit 100 can not be located on the lens unit 100 body, but the position of the optical center 1001 can still be determined according to the circular arc lines formed by the defective concentric circle lines, and the present application does not limit this.

[0065] Further, in the infrared detection device of this embodiment of the present application, the pyroelectric infrared sensor 20 is arranged in a quadrilateral form and has four sensing surfaces 21, so that based on the arrangement of the plurality of sensing surfaces 21, the sub-regions corresponding to each lens unit 100 of the Fresnel lens 10 are further sub-divided to improve the resolution of the infrared detection device related to the movement amplitude of the detected target.

[0066] It is worth mentioning that the infrared detection device is usually installed in a lamp to control the lighting state of the lamp based on the detection of the corresponding target to realize intelligent lighting, for example, in Figure 5A The warehouse environment shown in the schematic, using the structural design of the Fresnel lens 10 can guarantee the advantage of effective detection area of the infrared detection device in the long distance detection application scene, and the lamp is installed in a high installation mode to realize intelligent lighting in the warehouse environment. Among them, in the state that the Fresnel lens 10 is designed to satisfy L≤18mm, the corresponding Fresnel lens 10 has a significantly smaller peripheral diameter than the traditional Fresnel lens applied to long distance detection, and in the state that the Fresnel lens 10 is designed to satisfy H≤10mm, the light entrance surface 101 of the corresponding Fresnel lens 10 can be designed as a plane or a micro-arc surface. In this way, when the infrared detection device is installed in the lamp, it can correspond to Figure 5B Obtain a more natural and concealed installation effect.

[0067] Those skilled in the art can understand that the above embodiments are only examples, and the features of different embodiments can be combined with each other to obtain embodiments that can be easily thought of according to the disclosure of the present application but are not explicitly indicated in the drawings.

[0068] Those skilled in the art will understand that the embodiments of the present application described above and shown in the drawings are merely by way of example and do not limit the present application. The purpose of the present application has been completely and effectively achieved. The function and structural principle of the present application have been demonstrated and explained in the embodiments, and the embodiments of the present application can have any deformation or modification without departing from the principle.

Claims

1. An infrared detection device suitable for long-range detection, characterized in that comprises: a Fresnel lens, wherein the Fresnel lens has a center lens and two groups of lens units, wherein the center lens is provided with at least one lens unit and has a central axis, each of the groups of lens units is provided with a plurality of lens units and is arranged around the center lens, one of the groups of lens units is arranged around the center lens with the outer edge of the center lens as the inner edge, and the other group of lens units is arranged around the center lens with the outer edge of the previous group of lens units as the inner edge, wherein the total number of the lens units of the two groups of lens units is designed to be less than or equal to 16, the Fresnel lens forms a light entrance surface with the smooth surface of each lens unit, and each of the lens units of the Fresnel lens is designed with a plurality of concentric circular lines on the side opposite to the light entrance surface to have a converging property of a convex lens, wherein the focal length of the lens unit of the center lens is f, the distance between the optical center of the lens unit farthest from the central axis among the lens units of the two groups of lens units and the central axis is L, the Fresnel lens is designed in a state of L≤18mm, f≥15mm, and H≤10mm, and L / (f-H)≤0.7 is satisfied, wherein H is the height difference between the optical center of the lens unit of the center lens and the optical center of the lens unit farthest from the central axis among the lens units of the group of lens units in the direction along the central axis; and at least one pyroelectric infrared sensor, wherein the pyroelectric infrared sensor has at least one sensing surface and is arranged with the sensing surface facing the side of the Fresnel lens opposite to the light entrance surface.

2. The infrared detection device suitable for long-distance detection according to claim 1, wherein the number of the lens units of the center lens is one, and the central axis of the center lens is the principal optical axis of the lens unit thereof.

3. The infrared detection device suitable for long-distance detection according to claim 2, wherein the number of the lens units of the group of lens units with the outer edge of the center lens as the inner edge is four, and the number of the lens units of the other group of lens units is eight.

4. The infrared detection device suitable for long-distance detection according to claim 3, wherein the center lens provided with one lens unit has a square outer edge, the group of lens units with the outer edge of the center lens as the inner edge has a regular octagonal outer edge, and the four lens units are divided by the diagonal extension line of the square inner edge, and the other group of lens units has a circular outer edge with the outer edge of the previous group of lens units as the inner edge, and the eight lens units are divided by the diagonal extension line of the regular octagonal inner edge.

5. The infrared detection device suitable for long-distance detection according to claim 4, wherein the square outer edge of the center lens has a side length of 6±0.5mm, the regular octagonal outer edge of the group of lens units with the outer edge of the center lens as the inner edge has a side length of 7±0.5mm, and the circular outer edge of the other group of lens units has a radius of 17.5±0.5mm.

6. The infrared detection device of any one of claims 1 to 5, wherein the optical center of each lens unit of each lens unit group is designed to deviate from the geometric center of the lens unit in a direction biased toward the center lens.

7. The infrared detection device of claim 6, wherein the lens unit of each lens unit group farther from the center lens has a larger smooth surface area.

8. The infrared detection device of claim 7, wherein the Fresnel lens is further designed to satisfy L / (f-H)≤0.7 in a state of 11mm≤L≤13mm, 21mm≤f≤25mm, and H≤5mm.

9. The infrared detection device of claim 7, wherein the pyroelectric infrared sensor is arranged in a quadrate form, comprising: a center lens, wherein the center lens is arranged with at least one lens unit and has a central axis; and two lens unit groups, wherein each lens unit group is composed of a plurality of lens units and is arranged around the center lens, and one of the lens unit groups is arranged around the center lens with the outer edge of the center lens as the inner edge, and the other lens unit group is arranged around the center lens with the outer edge of the previous lens unit group as the inner edge, wherein the total number of the lens units of the two lens unit groups is designed to be less than or equal to 16, and the optical center of each lens unit of each lens unit group is designed to deviate from the geometric center of the lens unit in a direction biased toward the center lens, wherein the Fresnel lens forms an entrance surface with the smooth surface of each lens unit, and each lens unit of the Fresnel lens is designed with a plurality of concentric circular lines on the side opposite to the entrance surface to have a light converging property like a convex lens, wherein the focal length of the lens unit of the center lens is f, the distance between the optical center of the lens unit farthest from the central axis among the lens units of the two lens unit groups and the central axis is L, and the Fresnel lens is designed to satisfy L / (f-H)≤0.7 in a state of L≤18mm, f≥15mm, and H≤10mm, wherein H is the height difference between the optical center of the lens unit of the center lens and the optical center of the lens unit farthest from the central axis among the lens units of the lens unit group in the direction along the central axis.

10. Fresnel lens suitable for remote detection, characterized in that, ​ ​ ​ ​

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